JP5278869B2 - Synthetic smectite, dispersion containing the same, clay film, water-resistant film, and method for producing synthetic smectite and water-resistant film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide synthetic smectite which can form a waterproof film excellent well in water vapor-barrier properties and optical characteristics, and well reduced in elution of metal ions under high temperature and high humidity conditions. <P>SOLUTION: This synthetic smectite 100 includes a plurality of layers 10 including a pair of tetrahedral sheets 3 mainly having silicon ions and oxygen ions, and an octahedral sheet 1 sandwiched between the pair of tetrahedral sheets 3 and composed of an octahedral crystal structure mainly having aluminum ions and/or magnesium ions and oxygen ions and/or hydroxide ions. The synthetic smectite 100 is expressed by general formula (1): X<SP>+</SP><SB>a</SB>Al<SB>4-a</SB>Mg<SB>a</SB>Si<SB>8</SB>O<SB>20</SB>(OH)<SB>4</SB>, wherein a is a number satisfying formula (2): 0.01&le;a&lt;0.75; X<SP>+</SP>denotes a monovalent exchangeable cation, and contents of sodium ion and iron ion are 10 ppm or less, respectively. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a synthetic smectite, a dispersion containing the same, a clay film, a water resistant film, and a method for producing the synthetic smectite and the water resistant film.

  Smectite is a generic term for layered minerals having a plurality of layers composed of a pair of tetrahedral sheets mainly composed of silica and one octahedral sheet mainly composed of aluminum, magnesium, or iron sandwiched therebetween. is there. In addition to the elements that make up tetrahedron or octahedron sheets, smectite is usually an exchange of sodium ions, calcium ions, etc. between the two layers to compensate for the negative layer charge that occurs in these sheets. Contains cations.

  Smectites whose octahedral sheet is composed mainly of divalent cations such as magnesium and zinc are classified as trioctahedral smectites. Examples of the three-octahedral smectite include clay minerals called stevensite, hectorite, saponite, and soconite.

  On the other hand, smectites whose octahedral sheet is composed mainly of trivalent cations such as aluminum and iron are classified as dioctahedral smectites. Examples of the octahedral smectite include clay minerals called montmorillonite, beidellite, and nontronite (see Non-Patent Document 1, for example).

  Among these, montmorillonite, which is a kind of dioctahedral smectite, includes a layer composed of a pair of silica tetrahedral sheets and one aluminum octahedral sheet sandwiched therebetween. And since a part of trivalent aluminum of an octahedral sheet | seat is substituted by the bivalent magnesium, the octahedral sheet | seat has a negative layer electric charge. In order to compensate for this negative layer charge, an exchangeable cation such as sodium ion or calcium ion is contained between the two layers.

  Montmorillonite has unique properties such as ion exchange ability, intercalation function, swelling, and sol-gel properties in water due to the presence of such exchangeable cations. For this reason, unlike other clay materials such as kaolinite used as a ceramic raw material, they are used for special industrial applications such as boring mud, foundry sand, and organic smectite (see Non-Patent Document 2, for example).

  Montmorillonite used for these industrial uses is produced in various parts of the world such as the United States and Japan as natural montmorillonite. Naturally produced montmorillonite usually contains trivalent iron ions as impurities, and 0.3 to 22.8 atomic% of aluminum ion sites in the octahedron sheet is substituted with iron ions (for example, non-ionic). (See Patent Document 3 or 4). Naturally produced montmorillonite usually contains sodium ions, calcium ions, magnesium ions and the like as exchangeable cations in addition to iron ions.

  Further, as a synthetic smectite having a crystal structure similar to montmorillonite, an Fe-Mg-Si based synthetic smectite containing iron is known (see Patent Document 1). In this synthetic smectite, the octahedron sheet is composed of trivalent iron, and a part of the octahedron sheet is replaced with divalent magnesium, thereby expressing a negative layer charge. In addition, this synthetic smectite contains sodium ions, calcium ions, magnesium ions and the like as exchangeable cations as in the case of natural montmorillonite.

  Recently, it has been found that a film can be formed by laminating clay materials, and clay films having properties such as gas barrier properties, heat resistance, and flexibility have been proposed (for example, Patent Documents 2 and 3). reference). Such clay films are proposed for use in electronic device applications such as packaging materials for materials that dislike alteration such as foods and pharmaceuticals, liquid crystal displays and organic EL, and display devices that require excellent flexibility. ing.

Thus, as one of the clay film forming materials expected to be used in various applications, natural montmorillonite and Fe-Mg-Si based synthetic smectite having a crystal structure similar to montmorillonite can be mentioned. (For example, see Patent Documents 1 to 3).
Japanese Patent No. 2979141 Japanese Patent No. 3855003 Japanese Patent No. 3855004 Edited by Japan Clay Society, “Clay Handbook”, Gihodo Publishing, 58 pages Edited by Japan Clay Society, “Clay Handbook”, Gihodo Publishing, 9 pages Edited by the Japan Clay Society, “Clay Handbook”, Gihodo Publishing, p. 1304 Chemistry of Clays and Clay Minerals, Edited by A. C. D. Newman, John Wiley & Sons, 49, 1987

  The conventional Fe-Mg-Si synthetic smectite having a crystal structure similar to that of natural montmorillonite and montmorillonite described in Patent Document 1 adsorbs water molecules by exchangeable cations contained between the two layers. And easily disperse in water. When the water is removed from the dispersion in which these particles are dispersed and dried to form a film, the montmorillonite particles and the synthetic smectite particles can be oriented in the form of a film. The clay film having such a structure has excellent barrier properties against dry gases such as oxygen and nitrogen, and is excellent in heat resistance and flexibility. However, since the exchangeable cation contained between the two layers adsorbs water molecules, the water vapor barrier property is not sufficient.

  In addition, exchangeable cations contained in natural montmorillonite and conventional Fe-Mg-Si based synthetic smectite having a crystal structure similar to montmorillonite are desorbed and eluted from the layers under high temperature and high humidity conditions. For this reason, the clay film formed from these materials cannot be applied as a film substrate for electronic devices such as display devices that require high-purity materials.

  In order to improve the above points, the present inventors have made exchangeable positive effects on natural montmorillonite and the conventional Fe—Mg—Si based synthetic smectite described in Patent Document 1 having a crystal structure similar to montmorillonite. The heat treatment was performed by replacing the ions with lithium ions, and lithium ions were diffused into the octahedron sheet constituting the layer and fixed in the layer. That is, it was examined that lithium ions having an ion radius smaller than that of sodium ions, calcium ions, and the like are diffused into the layer (in the octahedral sheet) by a method such as heat treatment and held in the layer.

  However, in the method of replacing an exchangeable cation with a lithium ion by a technique such as an ion exchange method, substitution of the exchangeable cation contained in natural montmorillonite and a conventional Fe-Mg-Si based synthetic smectite with a lithium ion is performed. It was difficult to improve the rate. For this reason, by improving the said substitution rate, the elution of an exchangeable cation is fully reduced and the clay material and clay film which have sufficient water vapor | steam barrier property are calculated | required.

  On the other hand, conventional Fe-Mg-Si synthetic smectite having a crystal structure similar to natural montmorillonite and montmorillonite contains iron ions, so these materials and clays formed from such materials The film is colored brownish brown. For this reason, uncolored clay materials and clay films are required.

  The present invention was made in view of the above circumstances, the elution of metal ions under high-temperature and high-humidity conditions is sufficiently reduced, and a water-resistant film made of clay that is sufficiently excellent in water vapor barrier properties and optical characteristics, and a method for producing the same, It is another object of the present invention to provide a synthetic smectite capable of forming such a water resistant film and a method for producing the same. Moreover, it aims at providing the dispersion liquid containing the said synthetic smectite which can form the clay film which can form the said water-resistant film, and the said clay film.

In order to achieve the above object, in the present invention, a pair of tetrahedral sheets mainly having silicon ions and oxygen ions, and mainly aluminum ions and / or magnesium ions and oxygen so as to be sandwiched between the pair of tetrahedral sheets. A synthetic smectite including a plurality of layers including an octahedral sheet having an octahedral crystal structure having ions and / or hydroxide ions, and is represented by the following general formula (1), and contains sodium ions and iron ions Synthetic smectites each having a content of 10 ppm or less are provided.
X ⁺ _a Al _4-a Mg _a Si ₈ O ₂₀ (OH) ₄ (1)
[Wherein, a represents a number satisfying the following formula (2), and X ⁺ represents a monovalent exchangeable cation. ]
0.01 ≦ a <0.75 (2)]

  According to the present invention, it is possible to obtain a synthetic smectite or water-resistant film that does not elute metal ions under high-temperature and high-humidity conditions and is sufficiently excellent in water vapor barrier properties and optical properties. The present inventors infer the reason why a synthetic smectite having such characteristics can be obtained as follows.

  That is, by setting the sodium ion content of the synthetic smectite to 10 ppm or less, it is possible to prevent sodium ions from being present between the layers. When sodium ions are present between the layers, the surrounding water molecules are easily adsorbed, so that the barrier property against the water vapor of the synthetic smectite is reduced, and the elution amount of the exchangeable cation is increased. Further, by setting the iron ion content of the synthetic smectite to 10 ppm or less, coloring of the synthetic smectite can be suppressed and the visible light absorption rate can be lowered. Thereby, the optical characteristic of the water-resistant film formed can be improved. In addition, although the synthetic smectite of this invention can be used suitably as a raw material for clay film or water-resistant film formation, it is not limited only to a film formation use. Hereinafter, in some cases, “clay film” and “water resistant film” are collectively referred to as “film”.

Synthetic smectite of the invention, it contains at least one of lithium ion and hydrogen ions as exchangeable cations. Since lithium ions and hydrogen ions have a sufficiently small ion radius, they are stably held inside the layer. As a result, elution of exchangeable cations under high-temperature humidification conditions can be sufficiently reduced, and a synthetic smectite and water-resistant film that are sufficiently excellent in barrier properties against water vapor can be obtained. For example, sodium ions and calcium ions have an ionic radius larger than that of lithium ions and hydrogen ions, and thus are difficult to be present inside the synthetic smectite layer.

  The synthetic smectite of the present invention preferably has a montmorillonite type crystal structure. A synthetic smectite having such a crystal structure can easily contain exchangeable cations between layers. Thereby, excellent ion exchange ability and dispersibility can be provided. In addition, the exchangeable cation between layers can be easily moved into the layer by heat treatment or the like and stably held. Therefore, elution of exchangeable cations can be suppressed.

  In addition, the synthetic smectite of the present invention preferably has a film forming property. Thus, a clay film in which synthetic smectite particles are accumulated can be easily obtained. By subjecting such a clay film to a heat treatment, for example, a water-resistant film that is sufficiently excellent in water vapor barrier properties and optical properties and has water resistance can be easily obtained. Note that the synthetic smectite having film-forming properties is a dispersion containing the synthetic smectite in the container, for example, when a solid is dried at a temperature of room temperature or higher to form a clay film on the bottom of the container, Synthetic smectite that can be handled as a clay film at room temperature. On the other hand, the synthetic smectite having no film-forming property refers to a material that does not form a clay film and is, for example, in the form of powder when dried and solidified as described above.

  Moreover, the synthetic smectite of the present invention may have at least a part of lithium ions and hydrogen ions inside the octahedral sheet. Such a synthetic smectite can sufficiently prevent elution of lithium ions and hydrogen ions even under high temperature and high humidity conditions. Moreover, the water-resistant film which has the outstanding water vapor | steam barrier property and an optical characteristic can be comprised.

  In addition, the synthetic smectite of the present invention preferably has a [001] orientation plane spacing of 1.00 nm or less, which can be obtained by heating to 230 to 400 ° C. Such a synthetic smectite has a sufficiently reduced ratio of exchangeable cations remaining between the layers. Therefore, elution of exchangeable cations under high temperature humidification conditions can be sufficiently reduced. Moreover, a water-resistant film having such a synthetic smectite is sufficiently excellent in water vapor barrier properties.

  Moreover, it is preferable that the synthetic smectite of the present invention has a water absorption of 1% by mass or less at 25 ° C. and a relative humidity of 60%, which can be obtained by heating to 230 to 400 ° C. Such synthetic smectite can further sufficiently reduce elution of exchangeable cations under high temperature humidification conditions. Moreover, the water resistant film having such a synthetic smectite is more sufficiently excellent in water vapor barrier properties.

  Further, the synthetic smectite of the present invention is preferably one having an ion exchange capacity of 5 meq / 100 g or less, which can be obtained by heating to 230 to 400 ° C. Such synthetic smectite can further suppress the elution of exchangeable cations. Moreover, the water resistant film having such a synthetic smectite is more sufficiently excellent in water vapor barrier properties.

  The present invention also provides a dispersion containing the above-mentioned synthetic smectite and water as main components.

  Such a dispersion is excellent in dispersibility and can be suitably used as a raw material for forming a water-resistant film. In addition, the water-resistant film formed using such a dispersion does not easily elute metal ions under high temperature and high humidity conditions, and is sufficiently excellent in water vapor barrier properties and optical properties.

  In the present invention, a pair of tetrahedral sheets mainly having silicon ions and oxygen ions, and mainly aluminum ions and / or magnesium ions and oxygen ions and / or hydroxides so as to be sandwiched between the pair of tetrahedral sheets. A clay film in which a synthetic smectite having a plurality of layers including an octahedral sheet having an octahedral crystal structure having ions is laminated, and the synthetic smectite is represented by the general formula (1) and is exchangeable positive. Provided is a clay film having ions between layers, wherein the synthetic smectite has a sodium ion content and an iron ion content of 10 ppm or less, respectively.

  Since such a clay film has a synthetic smectite having a sodium ion content of 10 ppm or less, by performing a heat treatment or the like, exchangeable cations such as lithium ions and hydrogen ions can be exchanged from the synthetic smectite layer to the inside of the layer. Can be moved easily. Therefore, elution of metal ions under high temperature and high humidity conditions can be sufficiently reduced, and a water resistant film that is sufficiently excellent in water vapor barrier properties and optical characteristics can be easily formed. Moreover, since it has a synthetic smectite with an iron ion content of 10 ppm or less, it has excellent optical properties.

  The clay film of the present invention preferably has a thickness of 5 to 200 μm. By subjecting such a clay film to heat treatment or the like, it is possible to obtain a film capable of achieving both excellent mechanical strength and flexibility at a high level.

  In the present invention, a pair of tetrahedral sheets mainly having silicon ions and oxygen ions, and mainly aluminum ions and / or magnesium ions and oxygen ions and / or hydroxides so as to be sandwiched between the pair of tetrahedral sheets. A water-resistant film in which a synthetic smectite having a plurality of layers including an octahedral sheet having an octahedral crystal structure having ions is laminated. The synthetic smectite is represented by the general formula (1), and is exchangeable positive. Provided is a water-resistant film having at least part of ions inside an octahedron sheet, wherein the synthetic smectite has a sodium ion content and an iron ion content of 10 ppm or less, respectively.

  The synthetic smectite constituting such a water-resistant film can hold the exchangeable cation inside the layer, that is, in the octahedral sheet. Moreover, since the content of sodium ions is low, the amount of exchangeable cations remaining between the synthetic smectite layers is sufficiently reduced. Therefore, this water resistant film can sufficiently reduce the elution of metal ions under high temperature and high humidity conditions, and is sufficiently excellent in water vapor barrier properties. Furthermore, since the content of iron ions is low, it is hardly colored and has sufficiently excellent optical characteristics.

  The water-resistant film of the present invention preferably has a thickness of 5 to 200 μm. Such a water-resistant film can achieve both excellent mechanical strength and flexibility at a high level.

  Moreover, it is preferable that the water-resistant film of this invention is 20% or less of the light absorptance of light with a wavelength of 550 nm in thickness 50 micrometers. Such a water-resistant film has a sufficiently low light absorptivity, so that coloring is sufficiently reduced and has excellent optical properties.

  Further, the water resistant film of the present invention preferably has a water absorption rate of 0.5% by mass or less at 25 ° C. and a relative humidity of 60%. Such a water-resistant film has a sufficiently reduced elution of exchangeable cations under high-temperature humidification conditions, and is further sufficiently excellent in water vapor barrier properties.

  The present invention also includes a first step of obtaining a dispersion in which a mixed liquid containing a silicon compound, an aluminum compound, and a magnesium compound is mixed with an aqueous alkaline solution to disperse a hydrated composite hydroxide, a dispersion, and a lithium Provided is a method for producing a synthetic smectite comprising a second step of obtaining a precursor slurry by mixing ionic compounds that generate ions and / or hydrogen ions, and a third step of hydrothermal reaction of the precursor slurry. The synthetic smectite is mainly composed of a pair of tetrahedral sheets having silicon ions and oxygen ions, and mainly aluminum ions and / or magnesium ions and oxygen ions and / or hydroxides so as to be sandwiched between the pair of tetrahedral sheets. A plurality of layers including an octahedron sheet having an octahedral crystal structure having ions are provided and represented by the general formula (1). And it has a lithium ion and / or a hydrogen ion as an exchangeable cation between a some layer and the said some layer, and content of a sodium ion and an iron ion is 10 ppm or less, respectively.

  According to the production method described above, a synthetic smectite that is excellent in water dispersibility and can be easily formed into a film can be obtained. In addition, the synthetic smectite can easily move exchangeable cations from one layer to another inside the layer by heat treatment or the like. As a result, elution of metal ions under high temperature and high humidity conditions is sufficiently reduced, and a synthetic smectite that is sufficiently excellent in water vapor barrier properties and optical properties is obtained.

  In the method for producing a synthetic smectite of the present invention, the silicon compound is at least one compound selected from the group consisting of tetramethylorthosilicate, tetraethylorthosilicate, colloidal silica, fumed silica, and water glass, and the aluminum compound is nitric acid. It is at least one compound selected from the group consisting of aluminum, aluminum chloride and aluminum sulfate, the magnesium compound is at least one compound selected from the group consisting of magnesium nitrate, magnesium chloride, magnesium sulfate and magnesium carbonate, and the ionic compound is It is preferably at least one compound selected from the group consisting of lithium nitrate, lithium hydroxide, lithium chloride, hydrochloric acid, nitric acid, sulfuric acid and ammonia. As a result, a synthetic smectite having the above characteristics can be easily produced.

  Moreover, in the manufacturing method of the synthetic smectite of this invention, pH of the dispersion liquid obtained at a 1st process is 9.4-11.0, and pH of the precursor slurry obtained at a 2nd process is 10.0-12. In the third step, the precursor slurry is preferably subjected to a hydrothermal reaction for 24 hours or more under an autogenous pressure condition of 250 to 375 ° C. Thereby, the synthetic smectite represented by the general formula (1) having high purity can be produced in a high yield.

  In the present invention, the step of heat-treating the clay film having exchangeable cations between the layers to move at least a part of the exchangeable cations between the layers of the clay film into the octahedral sheet A method for producing a water resistant film is provided. The exchangeable cation of the water-resistant film obtained by such a production method is held inside the layer, that is, inside the octahedral sheet, and the amount of exchangeable cation remaining between the layers can be sufficiently reduced. As a result, the elution of metal ions under high temperature and high humidity conditions is sufficiently reduced, and a water resistant film that is sufficiently excellent in water vapor barrier properties and optical properties can be easily obtained.

  The heat treatment in the method for producing a water-resistant film of the present invention is preferably performed at 230 to 500 ° C. for 10 minutes to 48 hours. As a result, the cations between the layers of the synthetic smectite can be sufficiently moved into the layers, and the amount of exchangeable cations remaining between the layers can be further sufficiently reduced. Therefore, the elution of metal ions under high-temperature and high-humidity conditions can be further sufficiently reduced, and a water-resistant film that is further excellent in water vapor barrier properties and optical properties can be produced.

  According to the present invention, the elution of metal ions under high-temperature and high-humidity conditions is sufficiently reduced, and a water-resistant film made of clay that is sufficiently excellent in water vapor barrier properties and optical properties, a method for producing the same, and such a water-resistant film can be formed. Synthetic smectite and a method for producing the same can be provided. Moreover, the dispersion liquid containing the said synthetic smectite which can form the clay film which can form the said water-resistant film, and the said clay film can be provided.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the accompanying drawings. In the description of the drawings, the same reference numerals are used for the same or equivalent elements, and duplicate descriptions are omitted.

The synthetic smectite according to the present embodiment is mainly composed of a pair of tetrahedral sheets having silicon ions and oxygen ions, and mainly aluminum ions and / or magnesium ions and oxygen ions and / or sandwiched between the pair of tetrahedral sheets. Or it is synthetic smectite provided with two or more layers containing the octahedral sheet | seat which consists of an octahedral crystal structure which has a hydroxide ion, Comprising: It represents with the following general formula (1).
X ⁺ _a Al _4-a Mg _a Si ₈ O ₂₀ (OH) ₄ (1)
[Wherein, a represents a number satisfying the following formula (2), and X ⁺ represents a monovalent exchangeable cation. ]
0.01 ≦ a <0.75 (2)]
Moreover, content of a sodium ion and an iron ion is 10 ppm or less, respectively. In addition, the synthetic smectite which does not contain sodium ion and iron ion is also included in the synthetic smectite of the present invention.

FIG. 1 is a cross-sectional view schematically showing the structure of a synthetic smectite according to a preferred embodiment of the present invention. The synthetic smectite 100 includes a plurality of layers 10 each having an octahedral sheet 1 having an octahedral crystal structure and a pair of tetrahedral sheets 3 having a tetrahedral crystal structure sandwiching the octahedral sheet 1. And the exchangeable cation X ^<+> is provided between the some layers 10, ie, between layers.

The octahedral crystal structure constituting the octahedral sheet 1 includes aluminum ions (Al ³⁺ ), magnesium ions (Mg ²⁺ ), oxygen ions (O ²⁻ ), and hydroxide ions (OH ⁻ ). On the other hand, the tetrahedral crystal structure constituting the tetrahedral sheet 3 includes silicon ions (Si ⁴⁺ ) and oxygen ions (O ²⁻ ). The tetrahedral crystal structure is preferably composed of silicon ions and oxygen ions, but may have a trace amount of aluminum ions.

That is, the synthetic smectite 100 according to the present embodiment has a montmorillonite structure. The montmorillonite structure has a negative charge in the layer 10 because some of the aluminum ions of the octahedral sheet 1 have isomorphous substitution with magnesium ions and defects. In order to compensate for this negative charge and maintain electrical neutrality, exchangeable cations X ⁺ are provided between the layers 10.

The layer 10 has a vacant site in the octahedral sheet 1 and can stably hold the exchangeable cation X ⁺ that moves from the layer 10 with heat treatment at 230 to 400 ° C., for example. . As a method for identifying the crystal structure of the synthetic smectite 100, for example, an X-ray diffraction method can be suitably used.

Therefore, the synthetic smectite of the present invention preferably has a montmorillonite type and a similar crystal structure. The “montmorillonite type crystal structure” in this specification includes a structure similar to the montmorillonite type. For example, it has a basic structure of a layer in which an octahedral sheet composed of an octahedral crystal structure is sandwiched between a pair of tetrahedral sheets composed of a tetrahedral crystal structure, and exchangeable cations X ⁺ are held in the octahedral sheet 1. Including the crystal structure.

  In addition, in a structure similar to analsim which is a kind of zeolite, a crystal structure containing an exchangeable cation between the two layers 10 as shown in FIG. 1 cannot be obtained. Therefore, the effect of the present invention cannot be obtained with a structure similar to analsim.

  Synthetic smectite 100 has a sodium ion content of 10 ppm or less. Since the exchangeable cation existing between the layers 10 is held between the layers 10 by the van der Waals force with the layer 10, it easily elutes under high-temperature and high-humidity conditions. That is, since sodium ions cannot move into the layer, they are easily eluted. For this reason, by setting the sodium ion content to 10 ppm or less, the exchangeable cations remaining between the layers 10 after the heat treatment can be further reduced. Therefore, the elution of exchangeable cations can be further reduced, and a water-resistant film having further excellent water vapor barrier properties can be obtained.

The synthetic smectite 100 has an iron ion content of 10 ppm or less, and more preferably 5 ppm or less. Iron ions (Fe ³⁺ ) are colored ions, and synthetic smectite containing iron ions exceeding 10 ppm is colored and has a high visible light absorption rate. For this reason, the optical characteristic of the formed water-resistant film falls and it becomes difficult to use it as a film base material by which high optical characteristics, such as a display device use, are requested | required. The iron ions contained in the synthetic smectite 100 are present in the synthetic smectite 100 by replacing a part of the aluminum ions in the octahedral sheet 1. Since the octahedral crystal structure is usually composed of ionic bonds and has a strong bonding force, it is difficult to remove the iron ions by, for example, an ion exchange method.

  Sodium ions and iron ions can be quantified with a fluorescent X-ray apparatus. As the X-ray fluorescence analyzer, a scanning X-ray fluorescence analyzer, a wavelength dispersive X-ray fluorescence analyzer, and the like can be suitably used. In addition, other quantitative analysis methods such as high frequency induction plasma emission spectroscopy (ICP-AES), ion chromatography, and other analysis methods can be suitably used.

Moreover, it is preferable that the synthetic smectite 100 which concerns on this embodiment contains lithium ion (Li ^<+> ) or hydrogen ion (H ^{<+ >} ) as the exchangeable cation X ^<+> .

Lithium ions have an ionic radius of 0.068 nm, and hydrogen ions have an ionic radius of 0.038 nm. Since these ions have a small ion radius, they can be easily moved from between the layers 10 into the layers 10, that is, into empty sites in the octahedral sheet 1 by heat treatment or the like. It should be noted that exchangeable cations having an ion radius larger than that of lithium ions and hydrogen ions, such as sodium ions having an ion radius of 0.097 nm and calcium ions having an ion radius of 0.100 nm, can be applied to the octahedral sheet 1 even if heat treatment is performed. Cannot move to a free site inside. The exchangeable cation X ⁺ can be identified and quantified by extracting the exchangeable cation contained in the synthetic smectite 100 into an aqueous solution using a method such as the Schlenberger method or the high-temperature humidification method, and using ion chromatography. .

  In addition, when a in the above general formula (1) is less than 0.01, the amount of exchangeable cation is too small, and such synthetic smectite cannot be dispersed in water. On the other hand, when a in the general formula (1) is 0.75 or more, a crystal structure that can hold the exchangeable cation between layers or layers cannot be obtained.

When the synthetic smectite 100 is mixed with water, the exchangeable cation X ⁺ between the layers 10 adsorbs water molecules by hydrogen bonding force and hydrates, thereby obtaining a dispersion in which the particulate synthetic smectite 100 is dispersed. . The dispersion can suitably contain components other than water, for example, an alcohol solution such as methanol, ethanol and propanol, a dispersant such as sodium polyacrylate, and the like. A film-like molded body (clay film) can be obtained by separating and removing the liquid from the dispersion by a method such as drying or centrifugation and regularly laminating synthetic smectite particles. By subjecting such a clay film to a heat treatment or the like, it is possible to form a water-resistant film having high orientation and good water resistance.

  The synthetic smectite 100 preferably has a [001] orientation plane interval L1 of 1.2 to 1.25 nm before heat treatment (normal state). When the inter-surface distance L1 is less than 1.2 nm, since there are few exchangeable cations that adsorb water, it becomes difficult to form a stable dispersion because it swells in water, and a water-resistant film having excellent orientation can be formed. Tend to be difficult. On the other hand, when the inter-surface distance L1 exceeds 1.25 nm, the bonding force between the layers 10 becomes strong, so that it is difficult to form a stable dispersion by swelling in water, and a water-resistant film having excellent orientation Tends to be difficult to form. Here, the surface interval L1 in the [001] orientation can be measured by a method such as an X-ray diffraction method. The inter-surface distance L1 is the amount of exchangeable cations contained between the layers 10 of the synthetic smectite 100 or the amount of water molecules adsorbed by the exchangeable cations contained between the layers 10 of the synthetic smectite 100. Can be adjusted by changing

  In addition, the synthetic smectite 100 of the present embodiment preferably has a water absorption rate of 10% by mass or more, more preferably 15% by mass or more at 25 ° C. and a relative humidity of 60% before heat treatment (normal state). Since the synthetic smectite having a water absorption of 15% by mass or more has particularly high orientation, a water-resistant film having excellent orientation can be formed.

  The water absorption is based on the mass of the synthetic smectite that has been sufficiently absorbed by leaving it in an atmosphere at a temperature of 25 ° C. and a relative humidity of 60%, and the decrease in mass when the synthetic montmorillonite after moisture absorption is heated to 25-300 ° C. It can be measured by a method such as differential thermal balance. The water absorption before the heat treatment of the synthetic smectite can be adjusted by changing the amount of exchangeable cations contained between the layers 10 of the synthetic smectite 100.

  Synthetic smectite 100 preferably contains 50 to 150 meq / 100 g of exchangeable cation in an ion exchange capacity before heat treatment (normal state), and 50 to 120 meq / 100 g of exchangeable cation. It is more preferable to contain.

When the ion exchange capacity is less than 50 meq / 100 g, since there are few exchangeable cations that adsorb water, it tends to be difficult to form a stable dispersion. As a result, it tends to be difficult to form a film with excellent orientation. On the other hand, when the ion exchange capacity exceeds 150 meq / 100 g, the bonding force between the layers 10 becomes strong, so that the layer 10 swells excessively, and it tends to be difficult to form a stable dispersion. As a result, film formation with excellent orientation tends to be difficult. Here, the ion exchange capacity indicates the amount of the exchangeable cation X ⁺ existing between the layers 10 including the octahedral sheet, and can be measured by a method such as the Schlenberger method. The ion exchange capacity of the synthetic smectite before the heat treatment can be adjusted by changing the amount of exchangeable cations contained between the layers 10 of the synthetic smectite 100.

  Using the synthetic smectite 100 of this embodiment, a clay film, that is, a film-like molded body can be formed. In addition to the synthetic smectite 100 of this embodiment, the clay film can also contain, for example, smectites such as beidellite, stevensite, hectorite, and dispersants such as sodium polyacrylate. The clay film can be formed, for example, by regularly laminating a synthetic synthetic smectite obtained by subjecting the above dispersion to a treatment such as drying or centrifugation to separate and remove the liquid. .

  The thickness of the clay film is preferably 5 to 200 μm, more preferably 20 to 150 μm, and still more preferably 40 to 100 μm. When the thickness is less than 5 μm, the mechanical strength of the clay film tends to be insufficient. On the other hand, when the thickness exceeds 200 μm, the flexibility of the clay film tends to decrease.

  The thickness of the clay film can be measured by measuring a plurality of lengths in the thickness direction at each film cross section using an optical microscope or a scanning electron microscope, and calculating an average value thereof. At this time, in order to obtain a statistically reliable numerical value, it is preferable to measure five or more points of the length and calculate the average value.

  Moreover, the iron ion content of the clay film according to the present embodiment is 10 ppm or less. Therefore, this clay film is sufficiently reduced in coloring and has excellent optical properties. The light absorptance of the clay film at a wavelength of 550 nm is preferably 20% or less, more preferably 15% or less, and more preferably 10% or less in terms of a film thickness of 50 μm. Further preferred.

  When the said absorption rate exceeds 20%, the visible light absorption rate of a clay film will increase and there exists a tendency for the optical characteristic of a film to fall. In addition, the absorptance of light having a wavelength of 550 nm can be measured by, for example, ultraviolet-visible-near infrared region spectrophotometry. Moreover, the conversion value of the film thickness of 50 μm can be obtained by dividing the absorption rate (actual measurement value) by a numerical value obtained by dividing the film thickness by 50 μm.

  By subjecting the above-mentioned clay film to heat treatment, a water-resistant film (heat-treated film) that is sufficiently excellent in water vapor barrier properties and has sufficiently reduced elution of metal ions under high-temperature and high-humidity conditions can be obtained.

The reason why a water resistant film having such characteristics is obtained is as follows. The exchangeable cation X ⁺ between the layers 10 of the synthetic smectite 100 contained in the clay film moves to the inside of the layer 10, that is, the inside of the octahedral sheet 1 by heat treatment. This reduces the amount of exchangeable cation X ⁺ between layers 10. As a result, synthetic smectite loses hydration power and re-dispersibility in water is suppressed. Accordingly, it is possible to improve the water vapor barrier property of the heat treatment film finally obtained. The means for moving the exchangeable cation X ⁺ from between the layers 10 into the layer 10 is not limited to heat treatment.

FIG. 2 is a cross-sectional view schematically showing the structure of the synthetic smectite constituting the water-resistant film according to the preferred embodiment of the present invention. The synthetic smectite 200 is a pair of octahedral sheets 2 having an octahedral crystal structure having aluminum ions and magnesium ions and oxygen ions and / or hydroxide ions, and having a tetrahedral crystal structure having silicon ions and oxygen ions. A plurality of layers 20 sandwiched between the tetrahedral sheets 3 are contained. In addition, at least some of the octahedral sheets 2 have exchangeable cations X ⁺ . And the sodium content of the water-resistant film which concerns on this embodiment is 10 ppm or less. Therefore, there are almost no exchangeable cations X ⁺ between the layers 20. The synthetic smectite of the present invention includes those having exchangeable cations between the layers 10 as shown in FIG. 1 and those having exchangeable cations in the layer 20 as shown in FIG.

  The synthetic smectite 200 preferably has a [001] orientation plane spacing L2 of 0.90 to 1.00 nm. When the interplanar spacing L2 is less than 0.9 nm, the crystal structure of the synthetic smectite 200 tends to be impaired. On the other hand, when the surface spacing L2 exceeds 1.00 nm, the amount of exchangeable cations remaining between the heat-treated layers 20 is large, so that the barrier property against water vapor of the finally obtained waterproof film tends to be reduced There is. The plane distance L2 in the [001] direction can be measured by a method such as an X-ray diffraction method. The inter-surface distance L2 can be adjusted by changing the amount of exchangeable cations remaining between the layers 20 or the amount of water molecules adsorbed by the exchangeable cations remaining between the layers 20.

The water absorption rate of the synthetic smectite 200 is preferably 1% by mass or less, and more preferably 0.9% by mass or less. Synthetic smectite of 0.9% by mass or less has a sufficiently reduced residual amount of exchangeable cation X ⁺ between layers 20. Therefore, the water vapor barrier property is sufficiently excellent. On the other hand, when the water absorption rate exceeds 1% by mass, sufficient water vapor barrier property tends to be impaired. The water absorption of the synthetic smectite 200 can be adjusted by changing the ratio of exchangeable cations remaining between the layers 20 to the total exchangeable cations contained in the synthetic smectite 200.

  The ion exchange capacity of the synthetic smectite 200 is preferably 5 meq / 100 g or less. When the ion exchange capacity exceeds 5 meq / 100 g, the amount of water absorption tends to increase and the water vapor barrier property tends to decrease. Moreover, the metal ion elution amount under high temperature humidification conditions tends not to be sufficiently reduced. The ion exchange capacity of the synthetic smectite 200 can be adjusted by changing the ratio of exchangeable cations remaining between the layers 20 to the total exchangeable cations contained in the synthetic smectite 200.

  The thickness of the water-resistant film on which the synthetic smectite 200 is laminated is preferably 5 to 200 μm, more preferably 20 to 150 μm, and still more preferably 40 to 100 μm. When the thickness is less than 5 μm, the mechanical strength of the film tends to be insufficient. As a result, application to actual uses such as display device use and electronic device use tends to be difficult. On the other hand, when the thickness exceeds 200 μm, the flexibility of the film tends to decrease. In addition, the thickness of a water-resistant film can be measured like the above-mentioned clay film.

  Moreover, the iron ion content of the synthetic smectite 200 according to the present embodiment, that is, the water-resistant film is 10 ppm or less. Therefore, since the coloring is sufficiently reduced, it has excellent optical characteristics. The light absorptance of the water-resistant film at a wavelength of 550 nm is preferably 20% or less, more preferably 15% or less, and more preferably 10% or less in terms of a film thickness of 50 μm. Further preferred. The light absorption rate can be adjusted by changing the iron ion content of the water-resistant film.

  When the absorption rate exceeds 20%, the visible light absorption rate of the water-resistant film and the clay film increases, and the optical properties of the film tend to deteriorate. In addition, the conversion value of thickness 50 micrometers of the light absorption factor in wavelength 550nm of a water-resistant film can be measured and converted similarly to the above-mentioned clay film.

  The manufacturing method of the clay film and water-resistant film according to the present embodiment will be described in detail below with reference to the drawings as the case may be.

  In the film manufacturing method of the present embodiment, a first step of obtaining a dispersion in which a water-containing composite hydroxide is dispersed by mixing a mixed solution containing a silicon compound, an aluminum compound, and a magnesium compound and an alkaline aqueous solution; The second step of obtaining a precursor slurry by mixing the dispersion and an ionic compound that generates lithium ions and / or hydrogen ions by mixing with water, and hydrothermal reaction of the precursor slurry, the above general A third step of obtaining a synthetic smectite represented by formula (1) and having a plurality of layers and exchangeable cations between the plurality of layers, and a clay film in which a plurality of synthetic smectites are laminated, And a fourth step of moving at least a part of the exchangeable cations into the layer. Details of each step will be described below.

(First step)
First, a mixed solution containing a silicon compound, an aluminum compound, and a magnesium compound can be obtained by mixing an aqueous solution, an alcohol solution, or a dispersion containing each compound. The mixing ratio of each compound is preferably the same as the composition ratio of the chemical formula of the synthetic smectite of the general formula (1). In addition, it is preferable that content of a sodium ion and an iron ion is fully reduced as a liquid mixture.

  As the aqueous solution containing an aluminum compound, an aqueous solution containing at least one compound selected from the group consisting of aluminum nitrate, aluminum chloride, and aluminum sulfate can be suitably used.

  As an aqueous solution containing a magnesium compound, an aqueous solution containing at least one compound selected from the group consisting of magnesium nitrate, magnesium chloride, magnesium sulfate, and magnesium carbonate can be suitably used.

  As the aqueous solution or alcohol solution containing a silicon compound, an aqueous solution or alcohol solution containing at least one compound selected from the group consisting of tetramethylorthosilicate, tetraethylorthosilicate, colloidal silica, fumed silica, and water glass is preferably used. be able to. Of these, tetraethylorthosilicate, tetramethylorthosilicate, colloidal silica, and fumed silica that do not contain sodium ions are preferably used.

  As each compound, in order to obtain a water-resistant film having further excellent water vapor barrier properties and optical properties, it is preferable to use those having high purity. For example, it is preferable to use a solution or dispersion having a purity of 99.9 atomic% or more of silicon, aluminum, and magnesium with respect to all metal elements.

  Next, an aqueous alkaline solution was dropped into a mixed solution containing a silicon compound, an aluminum compound, and a magnesium compound, whereby the water-containing composite hydroxide of the synthetic smectite represented by the general formula (1) was dispersed in the solution. A dispersion can be prepared. Examples of the alkaline aqueous solution include a sodium hydroxide aqueous solution, a potassium hydroxide aqueous solution, and an ammonia aqueous solution. Among these, it is preferable to use an aqueous ammonia solution containing no metal element.

  From the viewpoint of obtaining the synthetic smectite represented by the general formula (1) with a small amount of impurities, the pH of the hydrated composite hydroxide is preferably 9.4 to 11.0, and preferably 9.8 to 10.5. preferable. In addition, adjustment of pH can be adjusted with the dripping amount of alkaline aqueous solution. When the pH of the hydrated composite hydroxide is less than 9.4, aluminum and magnesium tend to elute into water in an ionic state. For this reason, there exists a tendency which cannot fully obtain the synthetic smectite which satisfy | fills the composition ratio of the said General formula (1). On the other hand, when the pH of the hydrated composite hydroxide exceeds 11.0, the solubility of silicon increases and tends to elute in water. For this reason, there exists a tendency which cannot fully obtain the synthetic smectite which satisfy | fills the composition ratio of the said General formula (1). In addition, from the viewpoint of obtaining the synthetic smectite of the above general formula (1) with few impurities, the water-containing composite hydroxide obtained by the above operation is washed with water by a method such as a filtration method or a centrifugal separation method and then mixed with water. Thus, a dispersion used in the next step is preferable.

(Second step)
The second step is a step of obtaining a precursor slurry by mixing the dispersion and an ionic compound that generates lithium ions and / or hydrogen ions by mixing with water.

  Examples of the ionic compound used as the lithium ion source include lithium hydroxide, lithium nitrate, and lithium chloride. Examples of the ionic compound used as the hydrogen ion source include hydrochloric acid, nitric acid, sulfuric acid, and ammonia. A precursor slurry can be obtained by mixing an aqueous solution containing at least one of these ionic compounds with the dispersion.

  In order to improve the yield of the synthetic smectite, the mixing ratio of the ionic compound and the dispersion is preferably the same as the composition ratio of the chemical formula of the synthetic smectite of the general formula (1).

  In order to obtain a synthetic smectite represented by the general formula (1) having a high purity, the pH of the precursor slurry is preferably adjusted to 10.0 to 12.0, and is adjusted to 10.2 to 11.6. It is preferable. When the pH of the precursor slurry is less than 10.0, the existence ratio of hydroxide ions is unnecessarily low, and there is a tendency that a synthetic smectite satisfying the composition ratio of the general formula (1) cannot be sufficiently obtained. . On the other hand, when the pH of the precursor slurry exceeds 12.0, the presence ratio of hydroxide ions becomes higher than necessary, and there is a tendency that a synthetic smectite satisfying the composition ratio of the general formula (1) cannot be sufficiently obtained. is there.

(Third process)
The third step is a step of obtaining a synthetic smectite represented by the general formula (1) and having a plurality of layers and exchangeable cations between the plurality of layers by hydrothermal reaction of the precursor slurry. It is.

In this step, the precursor slurry is charged into a commercially available autoclave and subjected to a hydrothermal reaction.
The temperature range of the hydrothermal reaction is preferably 250 to 375 ° C, and more preferably 250 to 350 ° C. When the temperature of the hydrothermal reaction is less than 250 ° C., a self-generated pressure sufficient to obtain the synthetic smectite of the general formula (1) cannot be obtained, and the reaction tends not to proceed sufficiently. On the other hand, when the hydrothermal reaction temperature exceeds 375 ° C., the moisture contained in the precursor slurry becomes a supercritical state, the solubility of the solid component in water changes significantly, and the component of the synthetic smectite is easily eluted in water. Tend.

  As a self-generated pressure at the time of hydrothermal reaction, it can be 40-70 MPa, for example. The reaction time of the hydrothermal reaction is preferably 24 hours or longer. If it is less than 24 hours, the hydrothermal reaction tends not to proceed sufficiently. The upper limit of the reaction time is not particularly limited.

  By this hydrothermal reaction, a gel-like synthetic smectite 100 (FIG. 1) dispersed in water can be obtained. The synthetic smectite 100 is separated from water by a centrifugal separation method or a filtration method, and the resultant synthetic smectite is subjected to a heat treatment to form a particulate synthetic smectite 200 (FIG. 2), that is, a composition having an exchangeable cation in the layer. Smectite can be obtained. It is also possible to obtain a water-resistant film by laminating this synthetic smectite. In the film manufacturing method of the present embodiment, the water-resistant film can be efficiently manufactured by using the dispersion liquid in which the synthetic smectite 100 is dispersed in the next fourth step.

(Fourth process)
The fourth step is a step in which at least a part of the exchangeable cation is moved into the layer by heat-treating the clay film in which a plurality of synthetic smectites are laminated.

  In the fourth step, first, a clay film can be obtained by laminating and removing particulate synthetic smectite from the dispersion liquid in which synthetic smectite 100 is dispersed. As the dispersion, the dispersion obtained in the third step may be used as it is, or a dispersion obtained by re-dispersing the synthetic smectite 100 once separated from the dispersion may be used.

  The content of the synthetic smectite 100 with respect to the entire dispersion is preferably 0.5 to 10% by mass. When the content of synthetic smectite 100 in the dispersion is less than 0.5% by mass, drying tends to require a long time. Moreover, when content of the synthetic smectite 100 in a dispersion liquid exceeds 10 mass%, there exists a tendency for the dispersibility of the synthetic smectite 100 to fall and to form the clay film which has a uniform film thickness.

From the viewpoint of obtaining a dense clay film having a more uniform film thickness, the drying temperature of the dispersion is preferably less than the boiling point of water. The drying rate is preferably such that the evaporation rate of water from the surface of the dispersion is 0.01 to 1.0 g · cm ² · h by controlling the temperature and relative humidity in the drying apparatus. When the evaporation rate of water is less than 0.01 g · cm ² · h, it tends to require a long time to dry and remove moisture. On the other hand, when the water evaporation rate exceeds 1.0 g · cm ² · h, the density of the clay film tends to be impaired.

  The thickness of the clay film can be adjusted by changing the amount of the dispersion used and the content of the synthetic smectite contained in the dispersion.

Next, the clay film is subjected to heat treatment to produce a water-resistant film on which the synthetic smectite 200 (FIG. 2) is laminated. By this heat treatment, the exchangeable cation X ⁺ between the layers can be moved into the layer, that is, into the octahedral sheet 1. The heating temperature in the heat treatment is preferably 230 to 500 ° C, and more preferably 300 to 450 ° C. When the heating temperature is less than 230 ° C., the exchangeable cation X ⁺ tends to hardly move from between the layers 10 into the octahedral sheet 1. Therefore, there is a tendency that the water vapor barrier property of the water-resistant film is lowered and the elution of exchangeable cations under high temperature humidification conditions cannot be sufficiently suppressed. On the other hand, when the heating temperature exceeds 500 ° C., the hydroxide ions in the synthetic smectite 100 may be dehydrated and the crystal structure may be different, and the flexibility tends to be impaired.

The heating time in the heat treatment is preferably 10 minutes to 48 hours, more preferably 20 minutes to 24 hours. There is no problem even if the heating time exceeds 48 hours, but it is preferable to set the upper limit to 24 hours for practical use. On the other hand, when the heating time is less than 10 minutes, the exchangeable cation X ⁺ does not sufficiently move from the interlayer into the layer, that is, into the octahedral sheet 1, and the exchangeable cation remaining between the layers 20. There is a tendency for the amount of X ⁺ to increase. Therefore, there is a tendency that the water vapor barrier property of the water-resistant film is lowered and the elution of exchangeable cations under high temperature humidification conditions cannot be sufficiently suppressed.

  The heat treatment can be performed in a nitrogen atmosphere in addition to normal air. Moreover, the thickness of the water-resistant film obtained by the manufacturing method described above can be adjusted by changing the thickness of the clay film to be used.

  Moreover, it is preferable that the water absorption rate in 25 degreeC and 60% of relative humidity of the water-resistant film obtained by this embodiment is 0.5 mass% or less. When the water absorption rate of the water-resistant film exceeds 0.5% by mass, the water vapor barrier property of the water-resistant film tends to decrease, and the elution of exchangeable cations under high-temperature humidification conditions cannot be sufficiently suppressed.

The water-resistant film obtained by the above-described production method has an effect that the water vapor barrier property is sufficiently excellent while maintaining the excellent flexibility and gas barrier property originally possessed by the film obtained from the synthetic smectite of the present embodiment. Moreover, it is excellent also in water resistance and can fully suppress elution of metal ions under high temperature humidification conditions. Furthermore, since this water-resistant film is obtained by incorporating the exchangeable cation X ⁺ into the octahedral sheet 2 while maintaining the crystal structure inherent to montmorillonite, it also has excellent heat resistance and high purity characteristics. Furthermore, this water-resistant film has excellent optical properties since the iron content is sufficiently reduced.

  The preferred embodiment of the present invention has been described above, but the present invention is not limited to the above embodiment.

  EXAMPLES Hereinafter, although this invention is demonstrated more concretely based on an Example and a comparative example, this invention is not limited to a following example at all.

Example 1
<Production of synthetic smectite (Li ⁺ _0.7 Al _3.3 Mg _0.7 Si ₈ O ₂₀ (OH) ₄ )>
First, 20 ml of tetraethylorthosilicate (manufactured by Tama Chemical Industry Co., Ltd., purity 99.95 mass%) was mixed with 5 ml of a 1N aqueous nitric acid solution and 2.5 ml of distilled water. Ethanol (manufactured by Wako Pure Chemical Industries, Ltd., purity: 99.9% by mass) was mixed with this so that the total amount became 100 ml, to obtain a tetraethyl orthosilicate-containing ethanol solution.

  Separately, 15.47 g of aluminum nitrate (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) and 2.24 g of magnesium nitrate (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) Was dissolved in 100 ml of distilled water to obtain a solution. This solution was mixed with the above tetraethyl orthosilicate-containing ethanol solution 100 ml to obtain a mixed solution. To this mixed solution, 32.57 g of a 28% by mass aqueous ammonia solution was added dropwise at a dropping rate of 6.0 ml / min and mixed to obtain a hydrated composite hydroxide having a pH of 9.8.

  Lithium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) 0.37 g was mixed with the obtained hydrous composite oxide, and distilled water was further mixed so that the total amount was 250 ml, A body slurry was obtained. In addition, pH of the obtained precursor slurry was 10.8.

Next, this precursor slurry was charged into a stainless steel autoclave and subjected to a hydrothermal reaction at 300 ° C. for 48 hours under a self-generated pressure, thereby producing Li ⁺ _0.7 Al _3.3 Mg _0.7 Si ₈ O _20. A synthetic smectite represented by the chemical formula (OH) ₄ was obtained. The synthetic smectite thus obtained was a colorless translucent gel substance.

<Evaluation of synthetic smectite>
Content of sodium ion and iron ion of the obtained synthetic smectite, crystal structure, interplanar spacing of [001] orientation before and after 400 ° C. heat treatment, water absorption (temperature 25 ° C., relative humidity 60%), exchangeable cation The type and ion exchange capacity were evaluated by the following procedure.

[Content of sodium ion and iron ion]
The fluorescent X-ray spectrum of the synthetic smectite was measured using a wavelength dispersive X-ray fluorescence analyzer (manufactured by Shimadzu Corporation, XRF-1800). In the measured spectrum, the sodium ion and iron ion contents contained in the synthetic smectite were calculated from the peak area intensity caused by sodium ions and iron ions. The results are shown in Table 1.

[Crystal structure of synthetic smectite]
The crystal structure was evaluated by the Green-Kelly method using an X-ray diffraction method. Specifically, first, 1 g of synthetic smectite and 100 ml of 1N lithium nitrate are mixed and placed in a Teflon (registered trademark) sealed container and shaken at a shaking speed of 100 rpm for 24 hours. The cation was saturated with lithium ions.

  Next, solid components are collected by centrifugal separation at 5000 rpm for 10 minutes, and the solid components are collected. The solid components are stored in a hot air circulating dryer (product name: EPFH) and 300 ° C. For 24 hours. The solid sample after the heat treatment was set in an X-ray diffractometer (manufactured by Rigaku, ATX-G) cell, and X-ray diffraction was measured. For measurement, CuKα rays were used, and 2θ was scanned from 2 to 70 ° at 1 ° / min. In the obtained X-ray diffraction pattern, the [001] orientation plane spacing was calculated from the 2θ position of the diffraction peak due to the [001] orientation spacing using the Bragg conditional expression and was designated as “plane spacing A”. When the obtained synthetic smectite has a montmorillonite structure, lithium ions move into the layer by the above-described heat treatment at 300 ° C. for 24 hours, so that the “interplanar spacing A” is 1.00 nm or less.

  Next, 1 g of the solid sample after measurement of “surface distance A” and 100 ml of glycerin were mixed and placed in a Teflon (registered trademark) sealed container, and shaken at a shaking speed of 100 rpm for 24 hours. Thereafter, the solid component was collected by centrifugal separation at 5000 rpm for 10 minutes, and the solid components were collected. The solid components were collected in a hot air circulating dryer (product name: EPFH) and stored at 60 ° C. Dried for 4 hours. About the sample after drying, the X-ray diffraction was measured on the same measurement conditions as "surface interval A", the surface interval of [001] direction was calculated, and it was set as "surface interval B". Here, when the synthetic smectite has a montmorillonite structure, lithium ions in the layer are completely immobilized in the layer and thus are not adsorbed by glycerin. Therefore, the surface spacing of the synthetic smectite does not change before and after glycerin mixing. On the other hand, for example, when the synthetic smectite has a “biderite structure” similar to the montmorillonite structure, the interplanar spacing changes by mixing with glycerin. Based on this premise, the crystal structure of the synthetic smectite was determined to be a montmorillonite structure when the difference between “face spacing A” and “face spacing B” was within 0.1 nm. The results are shown in Table 1.

[Spacing of [001] orientation]
The synthetic smectite was dried at 60 ° C. for 4 hours in the above-described hot-air circulating dryer, and then set in the X-ray diffractometer cell to measure the X-ray diffraction of the synthetic smectite. For measurement, CuKα rays were used, and 2θ was scanned from 2 to 70 ° at 1 ° / min. In the obtained X-ray diffraction pattern, the [001] orientation plane spacing (before heat treatment) was calculated from the 2θ position of the diffraction peak due to the [001] orientation plane spacing by Bragg's diffraction conditional expression. The results are shown in Table 1.

  The synthetic smectite was heat-treated at 400 ° C. for 30 minutes in the above-described hot-air circulating dryer. For the synthetic smectite after heat treatment, the [001] orientation plane spacing (after heat treatment) was derived in the same manner as described above. The results are shown in Table 1.

[Water absorption measurement]
The synthetic smectite was allowed to stand for 5 hours in an atmosphere having a relative humidity of 60% and a temperature of 25 ° C. for sufficient moisture absorption, and the mass of the synthetic smectite after moisture absorption was measured. Subsequently, the synthetic smectite after moisture absorption was set in a cell of a thermogravimetric analyzer, and thermogravimetric analysis was performed. The measurement conditions were a heating rate of 10 ° C./min, an air flow rate in the system of 50 ml / min, and a measurement temperature range of 25 to 300 ° C. The water absorption rate (before heat treatment) was calculated from the mass reduction rate by thermogravimetric analysis. The results are shown in Table 1.

  The synthetic smectite was heat-treated at 400 ° C. for 30 minutes in the above-described hot-air circulating dryer. About the synthetic smectite after heat processing, the water absorption rate (after heat processing) was derived | led-out similarly to the above. The results are shown in Table 1.

[Identification of exchangeable cation species and measurement of ion exchange capacity]
The exchangeable cation in the synthetic smectite was exchanged for ammonium ion by the Schlenberger method. The exchangeable cation species were identified by quantifying and qualifying the cations eluted at that time.

  Specifically, first, 0.1 g of synthetic smectite and 10 ml of 1N ammonium acetate were mixed and placed in a Teflon (registered trademark) sealed container and shaken at a shaking speed of 100 rpm for 24 hours for replacement. Sex cations were extracted. And the extract containing the extracted exchangeable cation was analyzed by an ion chromatograph (manufactured by Toa DKK Corporation, trade name: ICA-2000, column used: Toa DKK Corporation, PCI-321). The kind of exchangeable cation was identified from the obtained peak position. Moreover, the exchangeable cation was quantified from the obtained peak intensity, and the ion exchange capacity (before heat treatment) was calculated. The results are shown in Table 1.

  The synthetic smectite was heat-treated at 400 ° C. for 30 minutes in the above-described hot-air circulating dryer. For the synthetic smectite after the heat treatment, the ion exchange capacity (after the heat treatment) was derived in the same manner as described above. The results are shown in Table 1.

<Production of water-resistant film>
0.5 g of synthetic smectite was placed in a beaker, 25 g of distilled water (20 ° C.) was added thereto, and the mixture was stirred with a Teflon (registered trademark) rotor to obtain a dispersion in which synthetic smectite was dispersed in water. This dispersion was poured into a rectangular parallelepiped polypropylene container having a 5 cm square bottom to a height of 5 mm. Next, the container was accommodated in a hot air circulating dryer (product name: EPFH, manufactured by Isuzu Co., Ltd.) and heated at 60 ° C. for 4 hours to dry and remove moisture in the dispersion. Thus, a synthetic smectite clay film having lithium ions between layers was obtained. Next, a photograph of the cross section of the clay film was taken at a magnification of 1000 times using a scanning electron microscope (manufactured by Hitachi, S-4300), and the length of the cross section of the clay film in the thickness direction of the film was measured. . Measurement was carried out at 10 measurement positions selected at random, and the average value of 10 measurement values was taken as the thickness of the clay film. As a result, the thickness of the clay film was 84 μm.

  Next, in the same hot air circulation dryer, the film material is heated at 400 ° C. for 30 minutes, and the lithium ions between the layers are moved into the layer to obtain a heat-treated film (water resistant film). It was.

<Evaluation of water-resistant film>
The thickness of the water-resistant film, the light absorptance at a wavelength of 550 nm, the elution cation analysis, and the water vapor transmission rate were measured according to the following procedures.

[Measurement of water-resistant film thickness]
A photograph of a cross section of the water-resistant film was taken at a magnification of 1000 using a scanning electron microscope, and the length of the cross section of the water-resistant film in the thickness direction of the water-resistant film was measured. Measurement was carried out at 10 measurement positions selected at random, and the average value of 10 measurement values was taken as the thickness of the water-resistant film. The results are shown in Table 2.

[Absorptance measurement of light having a wavelength of 550 nm]
The light absorption rate of the water-resistant film at a wavelength of 550 nm was measured using an ultraviolet-visible-near infrared region spectrophotometer (manufactured by JASCO Corporation, trade name: V-570). The obtained measured value was converted to a thickness of 50 μm and used as the light absorption rate of the water-resistant film. In addition, in order to measure an accurate light absorption rate, baseline correction was performed using magnesium carbonate having a light absorption rate of 3% or less before the measurement. The results are shown in Table 2.

[Elution cation analysis]
A stainless steel pressure vessel was charged with 1.0 g of a water-resistant film and 35.16 g of ultrapure water, and allowed to stand for 24 hours under high-temperature humidification conditions at 120 ° C. to extract a cationic component. And the ion chromatograph measurement of the extract containing the extracted elution cation was performed, and the elution cation was identified from the obtained peak position. Further, the amount of cation elution was quantified from the obtained peak intensity. The results are shown in Table 2.

[Water absorption measurement]
The water-resistant film was allowed to stand for 5 hours in an atmosphere having a relative humidity of 60% and a temperature of 25 ° C. for sufficient moisture absorption, and the mass of the water-resistant film after moisture absorption was measured. Subsequently, the moisture-resistant film after moisture absorption was set in a cell of a thermogravimetric analyzer and thermogravimetric analysis was performed. The measurement conditions were a heating rate of 10 ° C./min, an air flow rate in the system of 50 ml / min, and a measurement temperature range of 25 to 300 ° C. The water absorption rate of the water-resistant film was calculated from the mass reduction rate by thermogravimetric analysis. The results are shown in Table 2.

[Water vapor permeability measurement]
Using a moisture sensor (Lyssy, trade name: L80-5000 type), water vapor transmission rate was measured as follows. The lower atmosphere was adjusted to a relative humidity of 100%, and the upper atmosphere was adjusted to a relative humidity of 9.9% or less, respectively, with a 50 cm ² water-resistant film. Then, the water vapor transmission rate (g / (m ² · day) is measured by measuring the time until the relative humidity of the atmosphere on the upper side of the water resistant film is changed from 9.9% to 10.1% by the water vapor passing through the water resistant film. ) Was calculated. The results are shown in Table 2.

(Example 2)
A synthetic smectite and a water resistant film were produced in the same manner as in Example 1 except that the hydrothermal reaction conditions of the precursor slurry were 300 ° C. and 72 hours. And it carried out similarly to Example 1, and evaluated the synthetic smectite and the water-resistant film. The results are shown in Tables 1 and 2.

(Example 3)
A synthetic smectite and a water resistant film were produced in the same manner as in Example 1 except that the hydrothermal reaction conditions of the precursor slurry were 350 ° C. and 48 hours. And it carried out similarly to Example 1, and evaluated the synthetic smectite and the water-resistant film. The results are shown in Tables 1 and 2.

Example 4
First, 5 ml of a 1N aqueous nitric acid solution was mixed with 12 g of colloidal silica (manufactured by Sigma Aldrich Co., LUDOX TM-50, 50% by weight of SiO ₂ content) with stirring. Distilled water was mixed with this so that the total amount became 100 ml to obtain a Si-containing colloidal aqueous solution. A synthetic smectite and a water resistant film were produced in the same manner as in Example 1 except that this Si-containing colloidal aqueous solution was used instead of the tetraethylorthosilicate-containing ethanol solution. And it carried out similarly to Example 1, and evaluated the synthetic smectite and the water-resistant film. The results are shown in Tables 1 and 2.

(Example 5)
<Production of synthetic smectite ^{_{(Li + 0.3 Al 3.7 Mg 0.3}} Si 8 O 20 (OH) 4)>
First, 5 ml of 1N aqueous hydrochloric acid and 2.5 ml of distilled water were mixed with 20.83 g of tetraethyl orthosilicate (manufactured by Tama Chemical Co., Ltd., purity 99.95% by mass). Ethanol (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) was mixed with this so that the total amount was 100 ml, to obtain 100 ml of a tetraethyl orthosilicate-containing ethanol solution.

  Separately, aluminum nitrate (Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) 13.13 g and magnesium nitrate (Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) 3.85 g Was dissolved in 100 ml of distilled water to obtain a solution. This solution was mixed with 100 ml of the above tetraethyl orthosilicate-containing ethanol solution to obtain a mixed solution. To this mixed solution, 34.62 g of 28 mass% ammonia aqueous solution was dropped and mixed at a dropping rate of 6.0 ml / min to obtain a hydrous composite hydroxide having pH = 10.2.

  To the obtained hydrous composite oxide, 0.63 g of lithium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) is mixed, and distilled water is further mixed so that the total amount becomes 250 ml, A precursor slurry was obtained. The pH of the obtained precursor slurry was 11.4.

Next, this precursor slurry was charged into a stainless steel autoclave and subjected to a hydrothermal reaction at 300 ° C. for 48 hours under an autogenous pressure condition, whereby Li ⁺ _0.3 Al _3.7 Mg _0.3 Si ₈ O _20. A synthetic smectite represented by (OH) ₄ was obtained. The synthetic smectite thus obtained was a colorless translucent gel substance. The obtained synthetic smectite was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Production and evaluation of water-resistant film>
A water-resistant film was produced in the same manner as in Example 1 using the obtained synthetic smectite.
The water resistant film was evaluated in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 1)
<Production of synthetic smectite (Na ⁺ _0.7 Al _3.3 Mg _0.7 Si ₈ O ₂₀ (OH) ₄ )>
First, 5 ml of 1N aqueous hydrochloric acid and 2.5 ml of distilled water were mixed with 20.83 g of tetraethyl orthosilicate (manufactured by Tama Chemical Co., Ltd., purity 99.95% by mass). Ethanol (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) was mixed with this so that the total amount was 100 ml, to obtain 100 ml of a tetraethyl orthosilicate-containing ethanol solution.

  Separately, 15.47 g of aluminum nitrate (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) and 2.24 g of magnesium nitrate (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) Was dissolved in 100 ml of distilled water to obtain a solution. This solution was mixed with 100 ml of the above tetraethyl orthosilicate-containing ethanol solution to obtain a mixed solution. To this mixed solution, 34.62 g of a 28% by mass aqueous ammonia solution was added dropwise at a dropping rate of 6.0 ml / min and mixed to obtain a hydrous composite hydroxide having a pH of 9.8.

  To the obtained hydrous composite oxide, 0.35 g of sodium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) is mixed, and further distilled water is mixed so that the total amount becomes 250 ml, A precursor slurry was obtained. The pH of the obtained precursor slurry was 10.6.

Next, this precursor slurry was charged into a stainless steel autoclave and subjected to a hydrothermal reaction at 300 ° C. for 48 hours under a self-generated pressure condition, whereby Na ⁺ _0.7 Al _3.3 Mg _0.7 Si ₈ O _20. A synthetic smectite represented by the chemical formula (OH) ₄ was obtained. The synthetic smectite thus obtained was a white slurry substance. Then, the synthetic smectite was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Production of water-resistant film>
Using this synthetic smectite, a water resistant film was produced in the same manner as in Example 1. The water resistant film was evaluated in the same manner as in Example 1. The results are shown in Table 2.

(Comparative Example 2)
<Production of synthetic smectite (Li ⁺ _0.7 Fe _3.3 Mg _0.7 Si ₈ O ₂₀ (OH) ₄ )>
First, 5 ml of 1N aqueous hydrochloric acid and 2.5 ml of distilled water were mixed with 20.83 g of tetraethyl orthosilicate (manufactured by Tama Chemical Co., Ltd., purity 99.95% by mass). Ethanol (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) was mixed with this so that the total amount was 100 ml, to obtain 100 ml of a tetraethyl orthosilicate-containing ethanol solution.

  Separately from this, iron nitrate (Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) 16.67 g and magnesium nitrate (Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) 2.24 g Was dissolved in 100 ml of distilled water to obtain a solution. This solution was mixed with 100 ml of the above tetraethyl orthosilicate-containing ethanol solution to obtain a mixed solution. To this mixed solution, 35.76 g of a 28 mass% aqueous ammonia solution was added dropwise at a dropping rate of 6.0 ml / min and mixed to obtain a hydrous composite hydroxide having a pH of 9.9.

  To the obtained hydrous composite oxide, 0.37 g of lithium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) is mixed, and distilled water is further mixed so that the total amount becomes 250 ml, A precursor slurry was obtained. The pH of the obtained precursor slurry was 10.9.

Next, this precursor slurry was charged into a stainless steel autoclave and subjected to a hydrothermal reaction at 300 ° C. for 48 hours under an autogenous pressure condition, whereby Li ⁺ _0.7 Fe _3.3 Mg _0.7 Si ₈ O _20. A synthetic smectite represented by the chemical formula (OH) ₄ was obtained. The product thus obtained was a brown gel material. Then, the synthetic smectite was evaluated in the same manner as in Example 1. The results are shown in Table 1.

<Production and evaluation of water-resistant film>
Using this synthetic smectite, a water resistant film was produced in the same manner as in Example 1. The water resistant film was evaluated in the same manner as in Example 1. The results are shown in Table 2.

  From the measurement results of the inter-surface spacing before and after the heat treatment in Table 1, it was confirmed that the synthetic smectites of Examples 1 to 5 had lithium ions moved from layer to layer by the heat treatment.

  From the results in Table 2, it was confirmed that the water-resistant films (heat-treated films) of Examples 1 to 5 were sufficiently reduced in the elution amount of exchangeable cations and had excellent water vapor barrier properties.

It is sectional drawing which shows typically the structure of the synthetic smectite which concerns on suitable embodiment of this invention. It is sectional drawing which shows typically the structure of the synthetic smectite which comprises the water-resistant film which concerns on suitable embodiment of this invention.

Explanation of symbols

  1, 2 ... octahedron sheet, 3 ... tetrahedron sheet, 10, 20 ... layer, L1, L2 ... spacing, 100, 200 ... synthetic smectite.

Claims (19)

A pair of tetrahedron sheets mainly having silicon ions and oxygen ions, and eight ions mainly having aluminum ions and / or magnesium ions and oxygen ions and / or hydroxide ions so as to be sandwiched between the pair of tetrahedron sheets. A synthetic smectite comprising a plurality of layers including an octahedral sheet having a plane crystal structure,
It is represented by the following general formula (1),
X ⁺ _a Al _4-a Mg _a Si ₈ O ₂₀ (OH) ₄ (1)
[Wherein, a represents a number satisfying the following formula (2), and X ⁺ represents a monovalent exchangeable cation. ]
0.01 ≦ a <0.75 (2)
The exchangeable cation contains at least one of lithium ion and hydrogen ion,
Synthetic smectite whose content of sodium ion and iron ion is 10 ppm or less respectively. Synthetic smectite of claim 1 having a crystal structure of montmorillonite. The synthetic smectite according to claim 1 or 2 , having film-forming properties. The synthetic smectite according to any one of claims 1 to 3 , comprising at least a part of the lithium ions and the hydrogen ions inside the octahedral sheet. The synthetic smectite according to any one of claims 1 to 4 , wherein the [001] orientation plane spacing obtained by heating to 230 to 400 ° C is 1.00 nm or less. The synthetic smectite according to any one of claims 1 to 5 , having a water absorption of 1% by mass or less at 25 ° C and 60% relative humidity, which can be obtained by heating to 230 to 400 ° C. The synthetic smectite according to any one of claims 1 to 6 , having an ion exchange capacity of 5 meq / 100 g or less, which can be obtained by heating to 230 to 400 ° C. A dispersion containing the synthetic smectite according to any one of claims 1 to 7 and water as main components. A pair of tetrahedron sheets mainly having silicon ions and oxygen ions, and eight ions mainly having aluminum ions and / or magnesium ions and oxygen ions and / or hydroxide ions so as to be sandwiched between the pair of tetrahedron sheets. A clay film in which a synthetic smectite having a plurality of layers including an octahedral sheet composed of a plane crystal structure is laminated,
The synthetic smectite is represented by the following general formula (1):
X ⁺ _a Al _4-a Mg _a Si ₈ O ₂₀ (OH) ₄ (1)
[Wherein, a represents a number satisfying the following formula (2), and X ⁺ represents a monovalent exchangeable cation. ]
0.01 ≦ a <0.75 (2)
The exchangeable cation contains at least one of lithium ion and hydrogen ion,
Having the exchangeable cation between the layers;
A clay film in which the content of sodium ions and iron ions in the synthetic smectite is 10 ppm or less, respectively. The clay film according to claim 9 , having a thickness of 5 to 200 μm. A pair of tetrahedron sheets mainly having silicon ions and oxygen ions, and eight ions mainly having aluminum ions and / or magnesium ions and oxygen ions and / or hydroxide ions so as to be sandwiched between the pair of tetrahedron sheets. A water-resistant film in which a synthetic smectite having a plurality of layers including an octahedral sheet composed of a plane crystal structure is laminated,
The synthetic smectite is represented by the following general formula (1):
X ⁺ _a Al _4-a Mg _a Si ₈ O ₂₀ (OH) ₄ (1)
[Wherein, a represents a number satisfying the following formula (2), and X ⁺ represents a monovalent exchangeable cation. ]
0.01 ≦ a <0.75 (2)
The exchangeable cation contains at least one of lithium ion and hydrogen ion,
Having at least a portion of the exchangeable cations within the octahedral sheet;
The water resistant film in which the content of sodium ions and iron ions in the synthetic smectite is 10 ppm or less, respectively. The water-resistant film according to claim 11 , having a thickness of 5 to 200 μm. The water-resistant film according to claim 11 or 12 , which has an absorptance of light having a wavelength of 550 nm at a thickness of 50 µm of 20% or less. The water-resistant film according to any one of claims 11 to 13 , which has a water absorption rate of 0.5% by mass or less at 25 ° C and a relative humidity of 60%. A first step of obtaining a dispersion in which a water-containing composite hydroxide is dispersed by mixing a mixed solution containing a silicon compound, an aluminum compound, and a magnesium compound, and an alkaline aqueous solution;
A second step of obtaining a precursor slurry by mixing the dispersion and an ionic compound that generates lithium ions and / or hydrogen ions;
It said precursor slurry comprises a third step of reacting hydrothermal, a method for producing a synthetic smectite of claim 1, wherein. The silicon compound is tetramethyl orthosilicate, tetraethyl orthosilicate, a colloidal silica, and at least one compound selected from Hyumudoshiri mosquitoes or Ranaru group, said aluminum compound is aluminum nitrate, selected from the group consisting of aluminum chloride and aluminum sulfate At least one compound selected from the group consisting of magnesium nitrate, magnesium chloride, magnesium sulfate and magnesium carbonate, and the ionic compound is lithium nitrate, lithium hydroxide, lithium chloride, The method for producing a synthetic smectite according to claim 15 , which is at least one compound selected from the group consisting of hydrochloric acid, nitric acid, sulfuric acid and ammonia. The pH of the dispersion obtained in the first step is 9.4 to 11.0,
The pH of the precursor slurry obtained in the second step is 10.0 to 12.0,
The method for producing a synthetic smectite according to claim 15 or 16, wherein in the third step, the precursor slurry is subjected to a hydrothermal reaction for 24 hours or more under an autogenous pressure condition of 250 to 375 ° C. The heat treatment is applied to the clay film according to claim 9 to move at least a part of the exchangeable cations between the layers of the clay film into the octahedron sheet. 11. A method for producing a water-resistant film according to 11 . In the said heat processing, the manufacturing method of the water-resistant film of Claim 18 heated at 230-500 degreeC for 10 minutes-48 hours.

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