JP2018193276A - Smectite Slurry - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a smectite slurry in which synthetic smectite having a small cation exchange capacity (CEC) and low water dispersibility is uniformly dispersed. SOLUTION: A smectite slurry in which a synthetic smectite having a CEC of 5 to 50 meq / 100 g, water, ammonia, an alcohol compound, a ketone compound, and / or a nitrile compound is mixed, and the content of ammonia in the slurry is determined. A smectite slurry having a synthetic smectite content of 0.1 mmol or more per 1 g of the slurry. The synthetic smectite is one or more smectites selected from K-type, Na-type, Li-type, NH4-type, Ca-type, Mg-type, Al-type, Fe-type, Cu-type or Zn-type, preferably Li-type smectite and /. Alternatively, a smectite slurry preferably of NH4 type smectite. A smectite slurry in which synthetic smectite is one or more selected from montmorillonite, hyderite, hetatrite, saponite or stibuntite. [Selection diagram] None

Description

  The present invention relates to a slurry obtained by stably dispersing a synthetic smectite powder having a small cation exchange capacity and low water dispersibility.

Industrial clay is used in various fields such as thickeners, binders, rheology modifiers, inorganic binders, civil engineering muds, water-stopping materials, and cosmetic raw materials.
A smectite represented by montmorillonite is known as an industrial clay. A general crystal structure of smectite is composed of a unit crystal layer having a 2: 1 layer structure in which a silicate tetrahedral sheet in which a network of silicate is spread is sandwiched between alumina octahedral sheets. In many cases, a part of the central atoms of each sheet is isomorphously substituted with other atoms having a low valence in the crystal layer. Since the entire crystal layer is negatively charged by this isomorphous substitution, cations are taken in between the crystal layers so as to neutralize this negative charge. For example, when Al ³⁺ of the alumina octahedral sheet is isomorphously substituted with Mg ²⁺ or Si ⁴⁺ of the silicate tetrahedral sheet is isomorphously substituted with Al ³⁺ , a negative charge is generated, and this negative charge is neutralized. In the form, cations are taken in between the crystal layers. In addition, this cation can exchange ions, and smectite generally exhibits cation exchange. The amount of cations that can be ion-exchanged is called cation exchange capacity (CEC), and is one of the indices indicating the properties of smectite.

  When smectite and water are mixed, the smectite layer peels off and swells. This swelling is considered to be caused by water penetrating between the crystal layers when the hydration energy generated by hydration of the exchangeable cation is higher than the binding energy such as van der Waals force between the crystal layers. In fact, a smectite with a small amount of cation between crystal layers and a small CEC is unlikely to cause water to enter between crystal layers and hardly cause delamination or swelling. For example, Li-fixed montmorillonite obtained by using the Hofmann-Klemen effect and subjecting Li-type montmorillonite to heat treatment has a small CEC, and its water dispersibility is greatly reduced compared to Li-type montmorillonite before heating.

If a clay film is formed using smectite having a small CEC, it is possible to obtain a functional film that is not easily hydrated and has excellent water resistance. From this point of view, the use value of smectite with small CEC is high. The clay film is generally formed by applying a slurry in which clay is dispersed and drying the applied film. However, since smectites with small CEC have low water dispersibility, it is difficult to form a slurry that is uniformly dispersed at a desired concentration, and it is difficult to form a functional film by a coating method.
Under such circumstances, it has been studied to increase the water dispersibility of smectite having a small CEC and to form a clay film having excellent water resistance by a coating method.
For example, in Patent Document 1, Li-type montmorillonite prepared from naturally-derived montmorillonite is heat-treated, and as Li-fixed montmorillonite, this Li-fixed montmorillonite, ammonia, water, and a polar organic solvent having a formamide group are included. It is described that, by mixing, a montmorillonite slurry in which Li-fixed montmorillonite is stably dispersed in an aqueous medium can be obtained.

JP2015-147300A

  As described in Patent Document 1, in naturally derived smectite, CEC is generally controlled by heat treatment. On the other hand, smectite can also be synthesized artificially. In this synthetic smectite, the CEC of the obtained smectite can be adjusted as appropriate simply by controlling the synthesis conditions (such as the atomic composition of the synthesis raw material). Naturally-derived smectites are generally colored (usually yellowish), whereas synthetic smectites are highly transparent. Therefore, synthetic smectite has a high utility value in the formation of a water-resistant film.

  Then, this invention makes it a subject to provide the smectite slurry formed by uniformly disperse | distributing the synthetic smectite with small CEC and low water dispersibility, the clay film | membrane using this slurry, and the manufacturing method of the said slurry.

  As a result of intensive investigations in view of the above problems, the present inventors have determined that a synthetic smectite powder having low CES in a specific low range and having low water dispersibility is mixed with water, a specific amount of ammonia, and a specific organic compound (polar organic). It has been found that the dispersibility of the synthetic smectite can be effectively increased and a uniform slurry with high transparency can be obtained. The present invention has been further studied based on these findings and has been completed.

That is, the said subject of this invention was solved by the following means.
[1]
A smectite slurry comprising a synthetic smectite having a cation exchange capacity of 5 to 50 meq / 100 g, water, ammonia, an alcohol compound, a ketone compound, and / or a nitrile compound,
The smectite slurry, wherein the ammonia content in the slurry is 0.1 mmol or more per 1 g of the synthetic smectite content in the slurry.
[2]
The synthetic smectite is one or more smectites selected from K-type, Na-type, Li-type, NH ₄ -type, Ca-type, Mg-type, Al-type, Fe-type, Cu-type, and Zn-type smectites. The smectite slurry according to [1].
[3]
The smectite slurry according to [1] or [2], wherein the synthetic smectite is Li type smectite and / or NH ₄ type smectite.
[4]
The smectite slurry according to any one of [1] to [3], wherein the synthetic smectite is one or more selected from montmorillonite, beidellite, hectorite, saponite, and stevensite.
[5]
The smectite slurry according to any one of [1] to [4], wherein the content of smectite in the slurry is 1 to 30% by mass.
[6]
The smectite slurry according to any one of [1] to [5], wherein the slurry contains the nitrile compound.
[7]
In the slurry, the ratio of the content of the alcohol compound, the ketone compound and / or the nitrile compound in the total of the content of water and the content of the alcohol compound, the ketone compound and / or the nitrile compound is 10 to 80. The smectite slurry according to any one of [1] to [6], which is mass%.
[8]
A method for forming a clay film, comprising: applying the smectite slurry according to any one of [1] to [7] to form a coating film, and drying the coating film.
[9]
A method for producing a smectite slurry, comprising mixing at least a synthetic smectite having a cation exchange capacity of 5 to 50 meq / 100 g, water, ammonia, an alcohol compound, a ketone compound and / or a nitrile compound,
A method for producing a smectite slurry, wherein the ammonia is mixed in an amount of 0.1 mmol or more per 1 g of the synthetic smectite.
[10]
The method for producing a smectite slurry according to [9], wherein the ammonia is mixed by mixing ammonia water.

The smectite slurry of the present invention (hereinafter also simply referred to as “slurry of the present invention”) is obtained by uniformly dispersing a synthetic smectite having a low water dispersibility in which CEC is in a specific low range, and has high transparency.
The clay film of the present invention has excellent water resistance, high transparency, and excellent production efficiency.
According to the method for producing a smectite slurry of the present invention, it is possible to obtain a highly transparent slurry obtained by uniformly dispersing a synthetic smectite having a low water dispersibility and having a CEC in a specific low range.

<Smectite slurry>
The smectite slurry of the present invention (hereinafter also simply referred to as “the slurry of the present invention”) contains a synthetic smectite having a cation exchange capacity of 5 to 50 meq (milli equivalents) / 100 g, water, and ammonia. It contains a polar organic solvent selected from alcohol compounds, ketone compounds and / or nitrile compounds.
The slurry of the present invention is excellent in smectite dispersibility by promoting the peeling of smectite crystals between crystal layers, and has high transparency.
Each component which comprises the slurry of this invention is demonstrated in order.

(Smectite)
The smectite used in the present invention is a synthetic smectite and is different from a naturally derived smectite. That is, since synthetic smectite is composed of only elements derived from raw materials as compared with naturally-occurring smectite, the amount of impurities, organic substances, etc. is usually remarkably small and the crystal size is also small. Therefore, synthetic smectite has little color and can improve the transparency of industrial products using synthetic smectite.

  Synthetic smectite can control CEC by the raw material composition at the time of synthesis. Therefore, there is an advantage that smectite having a desired CEC can be synthesized without undergoing high-temperature heat treatment of the smectite.

The synthetic smectite used in the present invention is preferably one or more selected from montmorillonite, beidellite, hectorite, saponite, and stevensite. From the viewpoint of easy industrial production and commercial availability, stevensite, hectorite and / or saponite are preferred. Among them, it is preferable to use hectorite and / or stevensite in which the charge generation position exists in the octahedral sheet.
In the synthetic smectite used in the present invention, the cation existing between the crystal layers is not particularly limited. For example, Na (sodium) type, Li (lithium) type, K (potassium) type, NH ₄ (ammonium) type, Synthesis of one or more selected from each smectite of Ca (calcium) type, Mg (magnesium) type, Al (aluminum) type, Fe (iron) type, Cu (copper) type, and Zn (zinc) type Smectite can be used. The synthetic smectite used in the present invention is preferably a monovalent or divalent cation type, and more preferably a monovalent cation type. The larger the valence of the cation existing between the crystal layers, the more strongly the crystal layer is attracted. Therefore, in order to realize higher dispersibility, it is advantageous that the cation has a smaller valence. The synthetic smectite used in the present invention is more preferably NH ₄ type and / or Li type.

In the present invention, when “X-type smectite” (X is a cation), the amount of X ion (unit: meq) in the amount of leached cation of smectite (that is, the total amount of leached cation, unit: meq / 100 g, the same applies hereinafter). / 100 g) means a smectite with 70% or more. For example, in the case of Na-type smectite, it means smectite in which the amount of Na ⁺ (unit: meq / 100 g) in the amount of leached cation of smectite is 70% or more.
In this specification, the leaching cation amount of smectite is determined by leaching the smectite interlayer cation with 100 mL of 1 M ammonium acetate aqueous solution (1 M sulfuric acid for Al type smectite) over 4 hours with respect to 0.5 g of smectite. The concentration of various cations in the obtained solution is measured and calculated by ICP emission analysis or atomic absorption analysis.

The synthetic smectite used in the present invention has a small CEC of 5 to 50 meq / 100 g. The CEC is preferably 10 to 50 meq / 100 g, more preferably 15 to 50 meq / 100 g, and still more preferably 20 to 46 meq / 100 g.
The cation exchange capacity of smectite can be measured by a method according to the Schollenberger method (clay handbook 3rd edition, edited by the Japan Clay Society, May 2009, pages 453-454). More specifically, it can be measured by the method described in Japan Bentonite Industry Association Standard Test Method JBAS-106-77.

The synthetic smectite used in the present invention can be synthesized by a conventional method. For example, a starting gel can be prepared by mixing raw materials so as to have a desired composition ratio, and this gel can be subjected to hydrothermal treatment to synthesize smectite. The hydrothermal synthesis method can be performed using a mole-type reaction vessel or an autoclave. Moreover, the CEC of the obtained synthetic smectite can be adjusted to a desired low level by appropriately adjusting the raw material composition during synthesis by a conventional method.
The synthetic smectite used in the present invention can also be obtained commercially (for example, smecton-ST (trade name, manufactured by Kunimine Kogyo Co., Ltd.)).

  There is no restriction | limiting in particular in content of the synthetic smectite in the slurry of this invention, According to the objective, it can adjust suitably. From the viewpoint of ensuring fluidity as a slurry and making the kneading and stirring steps practically possible, the content of smectite in the slurry of the present invention is preferably 1 to 30% by mass. -25% by mass is more preferable, 1-20% by mass is more preferable, 1-15% by mass is further preferable, 1-10% by mass is further preferable, and 1-5% by mass is particularly preferable.

(ammonia)
The slurry of the present invention contains ammonia. As the ammonia source, any of ammonia water, gaseous ammonia, and liquid ammonia may be used. When slurry is produced at room temperature and atmospheric pressure, it is preferable to use ammonia water.
The content of ammonia in the slurry of the present invention is 0.1 mmol or more, preferably 0.2 mmol or more, more preferably 0.5 mmol or more, particularly preferably 1.0 mmol or more, per 1 g of synthetic smectite in the slurry. is there. By setting the ammonia content to 0.1 mmol or more, a sufficient number of molecules of ammonia can be infiltrated between the layers of the smectite crystals. It is estimated that dispersibility in That is, ammonia molecules bind to cations between crystal layers to form a large molecular weight complex. As a result, the charge density between the crystal layers decreases, the adhesion between the crystal layers loosens, and the medium penetrates between the crystal layers. It is estimated that it becomes easy to do.
In consideration of generation of ammonia odor and production cost, the content of ammonia in the slurry is preferably 10 mmol or less, more preferably 5 mmol or less, and further preferably 2 mmol or less, per 1 g of synthetic smectite in the slurry.

  In this specification, “per 1 g of smectite” specifically means per 1 g of smectite in the slurry derived from the smectite blended (dispersed) in the slurry. More specifically, it means per 1 g of mass of a processed product obtained by removing smectite mixed in the slurry from the slurry and treating the taken smectite at a temperature of 200 ° C. for 24 hours. The heat treatment is preferably performed in an open electric furnace. In this case, the relative humidity during heating is 5% or less, and the pressure is normal pressure.

The amount of ammonia per gram of smectite is the amount of ammonia in the slurry (mmol), the amount of smectite in the slurry (that is, the smectite derived from the blended smectite present in the slurry is taken out, and the extracted smectite is taken out. Is divided by (mass of processed product obtained by heat treatment at 200 ° C. for 24 hours) (unit: g).
The ammonia content in the smectite slurry can be measured by the indophenol method, the Kjeldahl method, gas chromatography, or ion chromatography.

(solvent)
The solvent (medium) contained in the smectite slurry of the present invention is a mixed solvent of water and a specific polar organic solvent. The polar organic solvent is an alcohol compound, a ketone compound and / or a nitrile compound.
Examples of the alcohol compound include methanol, ethanol, 2-propanol, ethylene glycol, and glycerin. Examples of the ketone compound include acetone, methyl ethyl ketone, diethyl ketone, methyl propyl ketone, and methyl isobutyl ketone. Examples of the nitrile compound include acrylonitrile and acetonitrile.
Among the above polar organic solvents, when the slurry is dried to remove the solvent, it is preferable to use one having a low boiling point from the viewpoint of reducing the residual solvent in the clay layer, and the polar boiling point is 120 ° C. or less. It is more preferable to use an organic solvent.
It is considered that the polar organic solvent enters between the smectite layers together with ammonia and contributes to dispersion in a chain manner. The reason for this is not clear, but alcohol compounds, ketone compounds, and nitrile compounds intercalate between crystal layers via polar groups, and this action is combined with water and ammonia, resulting in delamination of synthetic smectite. It is presumed that the dispersibility is effectively enhanced.

For example, a polyvalent cation smectite with a high CEC is strongly attracted to each other by the charge of the polyvalent cation, so that the layer spacing is difficult to spread and the crystalline swelling is limited (infinite swelling). Not). In order to improve the water dispersibility of the polyvalent cation smectite having such a low water dispersibility, it is known to use acetonitrile as a solvent (Japanese Patent Laid-Open No. 2006-141603). In this technique, the improvement in the water dispersibility of smectite is considered to be based on the interaction property between polyvalent cations present in large amounts between crystal layers and acetonitrile.
On the other hand, the smectite used in the present invention is a synthetic smectite having a small CEC and a remarkably small amount of cations existing between crystal layers. In this synthetic smectite, physical interaction such as van der Waals force acting between the layers is dominant in the adhesion between the crystal layers. In such a synthetic smectite having a small CEC, it has been completely unknown what kind of effect the polar organic solvent such as acetonitrile used for the interaction with the polyvalent cation in the above-mentioned technique produces. It was. Under such circumstances, the present inventors can prepare a slurry in which the synthetic smectite is uniformly dispersed by mixing a specific polar organic solvent with water and ammonia in the synthetic smectite having a small CEC. And the present invention has been completed.

In the slurry of the present invention, the proportion of the polar organic solvent in the total content of the polar organic solvent (alcohol compound, ketone compound and / or nitrile compound) and water is preferably 10% by mass or more, more preferably 15%. It is at least 20% by mass, more preferably at least 20% by mass. The proportion is preferably 80% by mass or less, more preferably 70% by mass or less, further preferably 60% by mass or less, further preferably 50% by mass or less, and particularly preferably 45% by mass or less.
In the present invention, in the case of “content of alcohol compound, ketone compound and / or nitrile compound”, among the alcohol compound, ketone compound and nitrile compound, when there is a compound not contained in the slurry, the compound is It means the total content of the excluded compounds. For example, when the slurry contains only an alcohol compound as the polar organic solvent, the “content of alcohol compound, ketone compound and / or nitrile compound” is the content of alcohol compound. Moreover, when a slurry contains only an alcohol compound and a nitrile compound as said polar organic solvent, "content of an alcohol compound, a ketone compound, and / or a nitrile compound" is the total content of an alcohol compound and a nitrile compound.

  In the slurry of the present invention, part or all of the polar organic solvent is preferably a nitrile compound (preferably acetonitrile). The proportion of the nitrile compound in the polar organic solvent contained in the slurry of the present invention is preferably 30% by mass or more, more preferably 50% by mass or more, still more preferably 70% by mass or more, further preferably 80% by mass or more, Especially preferably, it is 90 mass% or more. It is also preferred that all of the polar organic solvents contained in the slurry of the present invention are nitrile compounds.

  There is no restriction | limiting in particular in the water contained in the slurry of this invention, For example, when ammonia water is used as an ammonia source, the water in ammonia water comprises the water in a slurry. Moreover, the water in the slurry may contain water mixed separately from the ammonia water.

  When the content of smectite is high, the slurry of the present invention can be diluted to the desired content and used. Examples of the liquid used for this dilution include water and the above polar organic solvents.

(Other ingredients)
The slurry of the present invention is a silane coupling agent, a crosslinking agent, an organic polymer, a low molecular weight monomer, a non-swellable silicate compound, silica, a surfactant, as long as the effects of the present invention are not substantially impaired. It may contain inorganic nanoparticles and the like.

(Production of smectite slurry of the present invention)
Subsequently, the production of the slurry of the present invention will be described.
The smectite slurry of the present invention includes at least mixing the above-described synthetic smectite having a CEC of 5 to 50 meq / 100 g, water, ammonia, and one or more of the polar organic solvents. The synthetic smectite is preferably a powder.
In this mixing, the mixing amount of ammonia is 0.1 mmol or more, preferably 0.2 mmol or more, more preferably 0.5 mmol or more, and particularly preferably 1.0 mmol or more, per 1 g of the synthetic smectite. In addition, the mixing amount of the ammonia is preferably 10 mmol or less, more preferably 5 mmol or less, and further preferably 2 mmol or less per 1 g of the synthetic smectite.

  In the production of the slurry of the present invention, the proportion of the amount of the polar organic solvent in the total amount of water and the polar organic solvent is 80% by mass or less, preferably 70% by mass or less, more preferably 60% by mass or less, and still more preferably Is 50% by mass or less, particularly preferably 45% by mass or less. Moreover, the said ratio is preferable 10 mass% or more, 15 mass% or more is more preferable, and 20 mass% or more is further more preferable.

The mixing method of each raw material is not particularly limited, and the respective raw materials can be mixed simultaneously or in an arbitrary order. In mixing, a general impeller with a blade, a homomixer, a universal mixer, a rotation / revolution mixer, an Eirich mixer, or the like can be used. Especially, the universal mixer which can be mixed efficiently even if it is a high concentration slurry whose clay concentration exceeds 20 mass%, a rotation revolution mixer, etc. can be used suitably.
When mixing each raw material and preparing a slurry, there is no restriction | limiting in particular in the temperature at the time of mixing, Usually, it carries out at the temperature of 4-80 degreeC.

[Use of slurry of the present invention]
By mixing the resin component, the slurry of the present invention can be present as fine plate-like particles in the resin, and a composite material having high transparency can be obtained.
Further, by applying the slurry of the present invention on a substrate and drying the formed coating film to a desired level, a clay film having high transparency and excellent water resistance can be formed. This clay film can be used as, for example, a packaging film, an electronic substrate, a flame retardant film, a water vapor barrier film, an insulating film, a coat film, and the like.

  The present invention will be described in more detail based on examples, but the present invention is not limited thereto.

[Preparation Example 1] Preparation of synthetic smectite 10 g of smecton-ST (manufactured by Kunimine Kogyo Co., Ltd.), which is a Na-type synthetic smectite, was taken and washed and filtered with 100 g of 60 mass% isopropanol aqueous solution. Next, it was dried in a dryer at 105 ° C. and pulverized to obtain a Na type synthetic smectite powder.

[Preparation Example 2]
The Na-type synthetic smectite powder obtained in Preparation Example 1 is mixed with water so that the content of the synthetic smectite is 2% by mass, and this mixed solution is filled with a cation exchange resin ion-exchanged with ammonium ions. The solution was passed through the column. The mixed solution passed through the column was dried and pulverized to obtain NH ₄ type synthetic smectite powder.

[Preparation Example 3]
Na-type smectite was synthesized. The obtained synthetic smectite was washed and filtered in the same manner as in Preparation Example 1, dried and pulverized to obtain a synthetic smectite powder. This synthetic smectite powder was mixed with water so that the content of the synthetic smectite was 2% by mass, and this mixed solution was passed through a column packed with a cation exchange resin exchanged with lithium ions. Li-type synthetic smectite powder was obtained by drying and pulverizing the liquid mixture passed through the column.

[Measurement of CEC]
CEC was measured about each synthetic smectite powder obtained in Preparation Examples 1-3.
The CEC was measured by the method described in Japan Bentonite Industry Association Standard Test Method JBAS-106-77. The results are shown in the table below.

[Preparation of solvent]
<Solvent 1>
Distilled water was used as solvent 1.

<Solvent 2>
Solvent 2 was prepared by mixing 0.15 parts by mass of 28% by mass ammonia water (manufactured by Kanto Chemical Co., Inc.) with 99.85 parts by mass of distilled water.

<Solvent 3>
Solvent 3 was prepared by mixing 20 parts by mass of acetonitrile (manufactured by Kanto Chemical Co., Ltd., reagent grade) and 0.15 parts by mass of 28% by mass ammonia water (manufactured by Kanto Chemical Co., Ltd.) with 79.85 parts by mass of distilled water.

<Solvent 4>
Solvent 4 was prepared by mixing 40 parts by mass of 2-propanol (IPA, manufactured by Yamaichi Chemical Co., Ltd.) and 0.15 parts by mass of 28% by mass ammonia water (manufactured by Kanto Chemical Co., Ltd.) with respect to 59.85 parts by mass of distilled water. .

<Solvent 5>
To 89.85 parts by mass of distilled water, 10 parts by mass of methyl ethyl ketone (MEK, manufactured by Yamaichi Chemical Co., Ltd.) and 0.15 parts by mass of 28% by mass of ammonia water (manufactured by Kanto Chemical Co., Ltd.) were mixed.

  The compositions of the above solvents 1 to 5 are shown in the following table.

[Comparative Example 1-1]
19.7 g of solvent 1 was put in a screw tube bottle, and 0.3 g of Na-type synthetic smectite powder obtained in Preparation Example 1 was added. A rotor was put and stirred for 30 minutes using a magnetic stirrer to obtain a slurry.

[Comparative Example 1-2]
In Comparative Example 1-1, a slurry was obtained in the same manner as in Comparative Example 1-1 except that the NH ₄ type synthetic smectite powder obtained in Preparation Example 2 was used instead of the Na type synthetic smectite powder.

[Comparative Example 1-3]
In Comparative Example 1-1, a slurry was obtained in the same manner as in Comparative Example 1-1 except that the Li-type synthetic smectite powder obtained in Preparation Example 3 was used instead of the Na-type synthetic smectite powder.

[Comparative Example 2-1]
In Comparative Example 1-1, a slurry was obtained in the same manner as Comparative Example 1-1 except that solvent 2 was used instead of solvent 1.

[Comparative Example 2-2]
In Comparative Example 1-2, a slurry was obtained in the same manner as Comparative Example 1-2, except that Solvent 2 was used instead of Solvent 1.

[Comparative Example 2-3]
In Comparative Example 1-3, a slurry was obtained in the same manner as Comparative Example 1-3 except that Solvent 2 was used instead of Solvent 1.

[Example 1-1]
In Comparative Example 1-1, a slurry was obtained in the same manner as Comparative Example 1-1 except that solvent 3 was used instead of solvent 1.

[Example 1-2]
In Comparative Example 1-2, a slurry was obtained in the same manner as Comparative Example 1-2 except that Solvent 3 was used instead of Solvent 1.

[Example 1-3]
In Comparative Example 1-3, a slurry was obtained in the same manner as Comparative Example 1-3 except that Solvent 3 was used instead of Solvent 1.

[Example 2]
In Comparative Example 1-3, a slurry was obtained in the same manner as Comparative Example 1-3 except that Solvent 4 was used instead of Solvent 1.

[Example 3]
In Comparative Example 1-3, a slurry was obtained in the same manner as Comparative Example 1-3 except that Solvent 5 was used instead of Solvent 1.

  In Comparative Examples 2-1 to 2-3, Examples 1-1 to 1-3, and Examples 2 and 3, the ammonia content in the slurry is approximately 1.65 mmol per gram of synthetic smectite. .

[Test Example 1]
For each of the slurries prepared in Comparative Examples 1-1 to 1-3, Comparative Examples 2-1 to 2-3, Examples 1-1 to 1-3, and Examples 2 and 3, a spectrophotometer (UV-1700) was used. , Manufactured by Shimadzu Corporation), the transmittance (% T) at a wavelength of 500 nm was measured. The transmittance (% T) is calculated by the following formula using the transmittance ₁₀ of the solvent only and the transmittance I of the slurry.

Transmittance (% T) = (I / I ₀ ) × 100

Higher transmittance means higher transparency and means that the synthetic smectite is dispersed with a fine particle size. That is, it means that the peelability or dispersion between the smectite particles is good.
The results are shown in the table below. In the table below, “◯” in the column of solvent type indicates that the solvent was applied, and “O” in the column of synthetic smectite type indicates that the synthetic smectite was applied.

As shown in the above table, it can be seen that by using the solvent specified in the present invention, a synthetic smectite having a small CEC can be finely dispersed in a medium, and a highly transparent slurry can be obtained.

Claims (10)

A smectite slurry comprising a synthetic smectite having a cation exchange capacity of 5 to 50 meq / 100 g, water, ammonia, an alcohol compound, a ketone compound and / or a nitrile compound,
The smectite slurry, wherein the ammonia content in the slurry is 0.1 mmol or more per 1 g of the synthetic smectite content in the slurry. The synthetic smectite is one or more smectites selected from K-type, Na-type, Li-type, NH ₄ -type, Ca-type, Mg-type, Al-type, Fe-type, Cu-type, and Zn-type smectites. The smectite slurry according to claim 1, wherein The smectite slurry according to claim 1 or 2, wherein the synthetic smectite is Li type smectite and / or NH ₄ type smectite.   The smectite slurry according to any one of claims 1 to 3, wherein the synthetic smectite is one or more selected from montmorillonite, beidellite, hectorite, saponite, and stevensite.   The smectite slurry according to any one of claims 1 to 4, wherein a content of smectite in the slurry is 1 to 30% by mass.   The smectite slurry according to any one of claims 1 to 5, wherein the slurry contains the nitrile compound.   In the slurry, the ratio of the content of the alcohol compound, the ketone compound and / or the nitrile compound in the total of the content of water and the content of the alcohol compound, the ketone compound and / or the nitrile compound is 10 to 80. The smectite slurry according to claim 1, wherein the smectite slurry is mass%.   A method for forming a clay film, comprising: applying a smectite slurry according to any one of claims 1 to 7 to form a coating film; and drying the coating film. A method for producing a smectite slurry, comprising mixing at least a synthetic smectite having a cation exchange capacity of 5 to 50 meq / 100 g, water, ammonia, an alcohol compound, a ketone compound and / or a nitrile compound,
A method for producing a smectite slurry, wherein the ammonia is mixed in an amount of 0.1 mmol or more per 1 g of the synthetic smectite. The method for producing a smectite slurry according to claim 9, wherein the ammonia is mixed by mixing ammonia water.