JP2011057486A - Synthetic smectite, method for manufacturing the same, and composite film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a synthetic smectite capable of forming a film sufficiently reduced in ionic impurities, particularly sodium ions, and sufficiently excellent in flexibility; and to provide a method for manufacturing the same. <P>SOLUTION: The synthetic smectite 100 includes a main component represented by formula (1): X<SP>b+</SP><SB>a/b</SB>Al<SB>4+a</SB>Si<SB>8-a</SB>O<SB>20</SB>(OH<SB>1-c</SB>F<SB>c</SB>)<SB>4</SB>(1) (wherein X<SP>b+</SP>denotes an alkaline metal ion or an alkaline earth metal ion; and a, b and c denote numbers satisfying formulae (2) to (4): 0&lt;a&lt;2 (2), 1&le;b&le;2 (3), and 0&le;c&le;1 (4)), and has a content of sodium ions of &le;10 ppm. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a synthetic smectite, a method for producing the same, and a composite film containing the synthetic smectite and a polymer component.

  Smectite has a layer structure in which one octahedral sheet mainly composed of aluminum, magnesium, iron, or the like is sandwiched between two tetrahedral sheets composed mainly of silica. It is a generic term for layered minerals containing exchangeable cations such as alkali metal ions or alkaline earth metal ions between two layer structures in order to compensate for the negative layer charge generated in the octahedral sheet.

  Among them, smectites whose octahedral sheet contains trivalent cations such as aluminum and iron as main components are called dioctahedral smectites, and clay minerals such as montmorillonite, beidellite and nontronite are 2 It is classified into octahedral smectites (see, for example, Non-Patent Document 1).

  Montmorillonite, a type of 2-octahedral smectite, has a layer structure in which two silica tetrahedral sheets are sandwiched between one aluminum octahedral sheet, and a part of trivalent aluminum in the octahedral sheet is 2 By substituting with valent magnesium, a negative layer charge is developed in the octahedral sheet. In order to compensate for this negative layer charge, montmorillonite contains an exchangeable cation such as an alkali metal ion or an alkaline earth metal ion between the two layer structures.

  In addition, Baydelite, a kind of dioctahedral smectite, has a layer structure in which two silica tetrahedral sheets are sandwiched between one aluminum octahedral sheet, and tetrahedral silicon of the tetrahedral sheet. By substituting a part of trivalent aluminum, a negative layer charge is developed in the tetrahedral sheet. In order to compensate for this negative layer charge, bidelite contains exchangeable cations such as alkali metal ions or alkaline earth metal ions between the two layer structures.

  Montmorillonite and beidellite have unique properties such as ion exchange ability due to exchangeable cations, intercalation function, water absorption / adsorption function, swelling property, and sol-gel property in water. Therefore, unlike other clay materials such as kaolinite used as a ceramic raw material, it is used for special industrial applications such as thickening agents such as boring mud, foundry sand, paint and cosmetics, water absorption / adsorbent, organic smectite, etc. (For example, see Patent Document 1 and Non-Patent Document 2).

  Montmorillonite and beidellite used for these industrial applications are mainly produced as natural smectite in various parts of the world such as the United States and Japan. Natural smectite contains montmorillonite as a main component. On the other hand, the content of beidellite in natural smectite varies depending on the production region, and is usually 0 to 50% by mass. In addition, natural smectite contains trivalent iron ions derived from soil as impurities, and 0.3 to 22.8% by mass of aluminum in the octahedral sheet of montmorillonite or beidellite in natural smectite is iron. It is substituted by ions (for example, see Non-Patent Document 3 or 4). Natural smectites contain sodium ions, calcium ions, magnesium ions, and the like as exchangeable cations.

  On the other hand, a method for producing dioctahedral smectite containing beidellite has been proposed (see, for example, Patent Document 2). The dioctahedral smectite obtained by this production method does not usually contain the trivalent iron ions that natural smectite contains as impurities.

  By the way, in recent years, a clay film formed by laminating clay materials has been found, and has been proposed as a substrate excellent in gas barrier properties, heat resistance, flexibility, and the like (see, for example, Patent Documents 3 and 4). ). It has been proposed that these are applied to, for example, packaging materials for materials that do not want to be altered such as foods and pharmaceuticals, and electronic devices such as liquid crystal displays and display devices that require high flexibility such as organic EL. Yes.

  For example, in Patent Documents 3 and 4, a clay film formed by using the above-mentioned natural smectite and the dioctahedral smectite obtained by the production method of Patent Document 2 as a material is applied to packaging material use and electronic device use. Has been proposed.

JP 2007-236354 A JP-A-9-77510 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

  Clay films used in electronic device applications have excellent gas barrier properties, heat resistance, flexibility, and ionic impurities such as sodium ions, chloride ions, and nitrate ions, which cause deterioration of device characteristics. Need to be reduced.

  However, since a clay film produced from natural smectite contains a large amount of ionic impurities such as sodium ions and calcium ions, it is difficult to apply them to electronic devices. Moreover, since iron ions are contained as impurities, the clay film formed from natural smectite tends to be colored brown. For this reason, it is not sufficient as a film substrate for a display device that is required to reduce visible light absorption.

On the other hand, since the dioctahedral smectite obtained by the production method described in Patent Document 1 does not contain iron ion impurities, the resulting clay film is not colored, but a large amount of sodium ions are mixed in the synthesis stage. Since it contains, it is difficult to apply to an electronic device. Further, since the synthetic unreacted material such as amorphous SiO ₂ remains in the dioctahedral smectite obtained by the production method described in Patent Document 1, the flexibility of the obtained clay film is low. It tends to decrease. In order to improve flexibility, it is conceivable to mix a binder such as an organic polymer with the above two-octahedral smectite. However, when an organic component is mixed, heat resistance becomes insufficient. As a result, the use of clay films is limited, such as difficulty in application to fields requiring high heat resistance such as plant gaskets.

  One method for reducing the content of sodium ions is an ion exchange method. There are several ion exchange methods for clay, but the most commonly used method is to disperse sodium-type or calcium-type clay in a solution containing lithium ions, and to disperse the interlayer ions of the clay and the ions in the solution. How to exchange. In this ion exchange method, clay ions are dispersed in a lithium ion-containing solution (for example, a lithium chloride solution, a lithium nitrate solution, or a lithium sulfate solution), and the work of stirring and filtering is repeated several times to exchange interlayer ions. After that, the salt adhered as impurities is removed by repeatedly washing with water or alcohol. Although this ion exchange method is very time-consuming, complete ion exchange cannot be performed. In addition, the effects of impurities such as nitrate ions and chloride ions that cannot be completely washed out remain, and clay is also washed away during washing, so that the degree of ion exchange increases and the purity increases. .

  Moreover, in the ion exchange method using an ion exchange resin, about 15 atomic% of the total amount of interlayer sodium ions cannot be exchanged and remains in the clay.

  In view of the above circumstances, the present invention provides a synthetic smectite capable of forming a film having sufficiently excellent flexibility and a method for producing the same, while the content of ionic impurities, particularly sodium ions, is sufficiently reduced. The purpose is to do.

  Another object of the present invention is to provide a composite film excellent in light transmittance by containing the synthetic smectite and a polymer component.

In the present invention, the main component is the following formula (1);
^{_{X b + a / b Al 4}} + a Si 8-a O 20 (OH 1-c F c) 4 ··· (1)
[Wherein, X ^{b +} represents an alkali metal ion or an alkaline earth metal ion, and a, b and c each represent a numerical value satisfying the following formulas (2) to (4).
0 <a <2 (2)
1 ≦ b ≦ 2 (3)
0 ≦ c ≦ 1 (4)]
And a synthetic smectite having a sodium ion content of 10 ppm or less.

  According to the synthetic smectite of the present invention, it is possible to obtain a clay film that has a sufficiently reduced content of ionic impurities, particularly sodium ions, and is sufficiently excellent in flexibility. This reason is considered as follows, for example, but is not limited to the following reason. That is, when sodium ions are present in the layer structure, the surrounding water molecules are easily adsorbed, so that the barrier property against water vapor of the synthetic smectite is reduced and the elution amount of exchangeable cations is increased and formed. This causes a decrease in the flexibility of the clay film. However, in the present invention, the main component of the synthetic smectite is represented by the above formula (1) and the sodium ion content is 10 ppm or less, so that it is sufficient that sodium ions exist between the layer structures. Can be suppressed. This makes it possible to form a clay film having excellent flexibility.

When the sodium ion content exceeds 10 ppm, a part of ^{Xb +} in the formula (1) contained as the exchangeable cation in the formula (1) is substituted. As a result, for example, when used as a clay film for an electronic device, sodium ions contained between the layer structures or on the particle surface are eluted, causing a reduction in device characteristics.

  In addition, the synthetic smectite of this invention can be used suitably as a raw material for formation of a clay film or a film for electronic devices, for example. However, the synthetic smectite of the present invention is not limited to a film forming application, and can be applied to, for example, a thickener for cosmetics. In the present specification, the “clay film” and the “composite film” are sometimes collectively referred to as “film-shaped molded product”.

  The synthetic smectite of the present invention has a mass reduction rate of 2 to 5% by mass based on the mass before temperature increase when the temperature is increased from 150 ° C. to 300 ° C. at 10 ° C./min in dry air. Is preferred.

When the mass reduction rate is less than 2%, it means that the mixing ratio of amorphous components such as amorphous SiO ₂ into the synthetic smectite is high, and the formation of a film-like molded product obtained from the synthetic smectite is high. The film property and flexibility tend to be lowered.

  When the mass reduction rate exceeds 5%, it means that the mixing ratio of impurities such as nitrate and acetate remaining at the time of synthesis is high, and a film-like molded body obtained from the synthetic smectite by the influence of these impurities There is a tendency that the film-forming property and flexibility of the film are lowered.

  Moreover, it is preferable that the viscosity of the dispersion liquid disperse | distributed in water so that the content rate of the said synthetic smectite may be 2 mass% is 2000 mPa * s or more.

  When the viscosity of the dispersion is less than 2000 mPa · s, it means that the mixing ratio of non-dispersed components such as amorphous components in the dispersion is high, and the film-like molded product obtained from this synthetic smectite The film formability and flexibility tend to decrease.

  The synthetic smectite preferably has film-forming properties. Thereby, even when not using binders, such as an organic polymer, the film-form molded object on which the synthetic smectite particle was laminated | stacked can be obtained easily.

  Synthetic smectite having film-forming properties is synthesized by, for example, dispersing synthetic smectite in a solvent containing water as a main component to form a dispersion, and removing the solvent from the dispersion by drying or centrifugation. It means what can obtain the film-like molded object which the smectite particle | grain laminated | stacked.

  In addition, it is preferable that the mandrel bending radius of the film-like molded body made of only the synthetic smectite having a thickness of 50 μm is 5 mm or less. When the mandrel bending radius exceeds 5 mm, the flexibility of the film-shaped molded product tends to be lowered.

  The present invention also provides a composite film containing the synthetic smectite and a polymer component.

  The polymer component used for the composite film is preferably water-soluble. This makes it possible to uniformly mix the polymer component and the synthetic smectite when preparing a dispersion in which the synthetic smectite and the polymer component are dispersed in a water-based solvent. A composite film distributed more uniformly can be obtained.

  The composite film of the present invention preferably has a light transmittance of 80% or more at a wavelength of 550 nm at a film thickness of 30 μm.

  When the light transmittance at a wavelength of 550 nm of the composite film is less than 80%, the transparency of the composite film tends to decrease. As a result, the application is limited, for example, application to a display or the like that requires transparency becomes difficult.

  The present invention also includes a first step of obtaining a composite hydroxide slurry by mixing a solution containing silicon and aluminum and an alkali solution at a ratio satisfying the above formulas (1) to (4), and the above formula (1). ) To (4), a second step of preparing a precursor slurry by mixing the composite hydroxide slurry, a solution containing alkali metal ions or alkaline earth metal ions, and water, and the precursor. The slurry is hydrothermally reacted to obtain a product slurry, and after stirring the product slurry, solid-liquid separation is performed, the main component is represented by the above formula (1), and the sodium ion content is And a fourth step of obtaining a synthetic smectite of 10 ppm or less.

  According to the production method of the present invention, it is possible to produce a synthetic smectite that can be made into a dispersion liquid that is sufficiently excellent in viscosity and whiteness, and that can form a clay film that is sufficiently excellent in flexibility.

  In the above production method, the silicon source may be one or more selected from the group consisting of tetramethylorthosilicate, tetraethylorthosilicate, colloidal silica, fumed silica, and amorphous silica. The aluminum source can be one or more selected from the group consisting of aluminum nitrate, aluminum chloride, aluminum acetate, aluminum sulfate, aluminum oxide, and aluminum hydroxide. Furthermore, the alkali metal ion or alkaline earth metal ion source is at least one selected from the group consisting of nitrates, acetates, carbonates, oxalates, chlorides, hydroxides and fluorides containing them. Can do.

Moreover, in the said manufacturing method, it is preferable that the pH of the said composite hydroxide slurry in said 1st process is 4.0-11.0, and the pH of the said precursor slurry in said 2nd process is 8. 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 200 to 370 ° C. In the fourth step, After stirring the product slurry at 3000 rpm or more for 5 minutes or more, the product slurry is solidified by a centrifugal separation method in which the centrifugal acceleration is rotated at a centrifugal acceleration of 1.96 × 10 ⁴ m / s ² (2000 G) or more for 5 minutes or more. Liquid separation is preferable.

  In the first step, when the pH of the composite hydroxide slurry is less than 4.0, aluminum is easily eluted into water. As a result, it becomes difficult to control the composition of aluminum in the synthetic smectite, and it becomes difficult to obtain a synthetic smectite that satisfies the above formulas (1) to (4). On the other hand, when the pH of the composite hydroxide slurry exceeds 11.0, the solubility of silicon becomes high and it is easy to elute into water. As a result, it becomes difficult to control the composition of silicon in the synthetic smectite, and it becomes difficult to obtain a synthetic smectite satisfying the above formulas (1) to (4).

  In the second step, if the pH of the precursor slurry is less than 8.0, the proportion of hydroxide ions in the synthetic smectite tends to be unnecessarily low, and the pH of the precursor slurry is 12 If it exceeds .6, the proportion of hydroxide ions in the synthetic smectite tends to be higher than necessary. As a result, in any case, it becomes difficult to control the composition of the synthetic smectite, and it becomes difficult to obtain the synthetic smectite satisfying the above formulas (1) to (4).

  In the third step, when the temperature of the hydrothermal reaction is lower than 200 ° C., it is difficult to obtain a sufficient self-generated pressure, and the hydrothermal reaction tends not to proceed sufficiently. On the other hand, when the temperature exceeds 370 ° C., the water contained in the precursor slurry is in a supercritical state, so that the solubility of the solid component in water significantly changes. As a result, it becomes difficult to control the composition of the synthetic smectite, and it becomes difficult to obtain a synthetic smectite that satisfies the above formulas (1) to (4).

  Moreover, in the said 3rd process, when the hydrothermal reaction time of the said precursor slurry is less than 24 hours, there exists a tendency for reaction not to fully advance. In addition, if the hydrothermal reaction time is 24 hours, the said synthetic smectite can be obtained suitably. There is no particular limitation on the upper limit of the hydrothermal reaction time because the characteristics of the synthetic smectite obtained even if the hydrothermal reaction time is extended beyond 24 hours do not deteriorate.

  In the fourth step, when the stirring speed of the product slurry is less than 3000 rpm, it is difficult to sufficiently separate the dispersed components, and it is difficult to obtain a synthetic smectite satisfying the above formulas (1) to (4). is there. On the other hand, when the stirring time is less than 5 minutes, the separation of the dispersed components does not proceed sufficiently, and it is difficult to obtain synthetic smectite satisfying the above formulas (1) to (4). If the stirring time is 5 minutes, the synthetic smectite can be suitably obtained, and even if the stirring time is longer than 5 minutes, the characteristics of the obtained synthetic smectite will not deteriorate. There are no particular restrictions.

Furthermore, in the fourth step, when the centrifugal acceleration during the solid-liquid separation is less than 1.96 × 10 ⁴ m / s ² (2000 G), the separation of the dispersed components does not proceed sufficiently, and the above formula ( It tends to be difficult to obtain synthetic smectite satisfying 1) to (4). Moreover, when the centrifugal separation time is less than 5 minutes, the separation of the dispersed components is difficult to proceed sufficiently, and it is difficult to obtain synthetic smectite satisfying the above formulas (1) to (4). The synthetic smectite can be suitably obtained by setting the centrifugation time to 5 minutes or longer. In addition, since the characteristic of the synthetic smectite obtained even if it extends over 5 minutes and the centrifugation time is not deteriorated, there is no particular limitation on the upper limit of the centrifugation time.

  According to the present invention, it is possible to provide a synthetic smectite capable of forming a film having a sufficiently excellent flexibility and a method for producing the same while sufficiently reducing the content of ionic impurities, particularly sodium ions. it can.

  In addition, according to the present invention, by containing the synthetic smectite and the polymer component, a composite film excellent in flexibility and light transmittance is provided while the content of sodium ions is sufficiently reduced. be able to.

It is a schematic diagram which shows a part of layer structure of the synthetic smectite which concerns on one Embodiment of this invention. It is a schematic diagram which shows the layer structure in the aqueous solution of the synthetic smectite which concerns on one Embodiment of this invention.

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

[Synthetic smectite]
The synthetic smectite according to the present embodiment contains a component represented by the following formula (1) as a main component, and the sodium ion content is 10 ppm or less.
^{_{X b + a / b Al 4}} + a Si 8-a O 20 (OH 1-c F c) 4 ··· (1)
In addition, in said formula (1), ^{Xb +} shows an alkali metal ion or alkaline-earth metal ion, and a, b, and c show the numerical value which satisfy | fills following formula (2)-(4), respectively.
0 <a <2 (2)
1 ≦ b ≦ 2 (3)
0 ≦ c ≦ 1 (4)

FIG. 1 schematically shows the layer structure of the synthetic smectite according to the present embodiment. The synthetic smectite 100 is composed of a layer structure 10 having an octahedral sheet 1 composed of an octahedral crystal structure and a pair of tetrahedral sheets 3 composed of a tetrahedral crystal structure, and an exchange existing between a plurality of layer structures 10, that is, between the layer structures. And a positive cation ^{Xb +} . In the layer structure 10, the pair of tetrahedral sheets 3 sandwich the octahedral sheet 1. The octahedral crystal structure has aluminum ions (Al ³⁺ ) and oxygen ions (O ²⁻ ), and hydroxide ions (OH ⁻ ) or fluorine ions (F ⁻ ). On the other hand, the tetrahedral crystal structure has silicon ions (Si ⁴⁺ ), aluminum ions, and oxygen ions.

In addition, the content of sodium ions in the synthetic smectite 100 according to this embodiment is 10 ppm or less. When the content of sodium ions exceeds 10 ppm, sodium ions are substituted for a part of the exchangeable cation X ^{b +} and are present between the layer structures. As a result, for example, when used as a clay film for electronic device applications, sodium ions contained between the layer structures or on the particle surface are eluted, causing deterioration in device characteristics.

  In the synthetic smectite 100 according to this embodiment, the content of sodium ions is preferably 10 ppm or less, more preferably 5 ppm or less, and even more preferably 1 ppm or less. In addition, the sodium ion content of the synthetic smectite 100 can be measured by using, for example, an ICP-AES analysis method.

Synthetic smectite 100 according to the present embodiment includes a component represented by the above formula (1) as a main component, and as an auxiliary component, an amorphous component such as amorphous SiO ₂ , an ionic impurity, and a nitrate remaining during synthesis. Further, impurities such as acetate may be contained. The content of the component represented by the above formula (1) contained as the main component is preferably 70% by mass or more, more preferably 80% by mass or more, based on the total mass of the synthetic smectite 100. More preferably, it is 90% by mass or more.

  Further, the synthetic smectite 100 according to the present embodiment has a mass reduction rate when the temperature is increased from 150 ° C. to 300 ° C. at 10 ° C./min in dry air with an air flow of 50 ml / min, and the mass before the temperature increase. Is preferably 2 to 5% by mass based on the above.

When the above-mentioned mass reduction rate is less than 2%, since the mixing ratio of amorphous components such as amorphous SiO ₂ is high, the film formability and flexibility of the film-like molded body obtained from the synthetic smectite 100 are lowered. Tend to. On the other hand, when the mass reduction rate exceeds 5%, since the mixing ratio of impurities such as nitrate and acetate remaining at the time of synthesis is high, the film-formability and flexibility of the film-like molded body obtained from the synthetic smectite 100 are high. Tend to decrease.

The tetrahedral crystal structure of the synthetic smectite 100 according to this embodiment is composed of silicon ions, aluminum ions, and oxygen ions, and the tetrahedral sheet 3 has a negative charge. For this reason, when it is set as the dispersion liquid which used water as the solvent, the card house structure 200 as shown in FIG. 2 is formed with the repulsive force of several layer structure 10, and a dispersion liquid expresses high viscosity. On the other hand, when the mixing of amorphous components such as amorphous SiO ₂ having no water dispersibility becomes significant, the dispersibility of the synthetic smectite 100 in water becomes insufficient due to the influence. As a result, the film formability and flexibility of the film-like molded product tend to be lowered. Further, when the mixing ratio of impurities such as nitrate and acetate remaining at the time of synthesis is high, the film formability and flexibility of the film-like molded product tend to be lowered due to the influence of the impurities. In addition, as a mass reduction rate evaluation method, for example, a TG-DTA method can be suitably used.

  In addition, the synthetic smectite 100 according to the present embodiment may be a dispersion liquid in which a water-based solvent is dispersed. This dispersion can be suitably used for forming a clay film, and can also be suitably used for forming a composite film by mixing with a polymer component. In addition, it is preferable that the viscosity of the dispersion liquid when it is made to disperse | distribute in water so that the content rate of the synthetic smectite 100 which concerns on this embodiment may be 2 mass% is 2000 mPa * s or more.

  In the dispersion liquid in which the synthetic smectite 100 according to this embodiment is dispersed in a solvent containing water as a main component, the layer structure 10 forms the card house structure 200. At that time, since the layer structure 10 is arranged so as to form a polymer chain, the dispersion liquid becomes viscous. Here, when the viscosity of the dispersion liquid dispersed in water so that the content of the synthetic smectite 100 is 2% by mass is less than 2000 mPa · s, for example, an amorphous component such as an impurity component that is not dispersed in water. Since the mixing ratio is high, the film formability and flexibility of the film-like molded body obtained from the synthetic smectite 100 tend to decrease.

  Moreover, it is preferable that the viscosity of the dispersion liquid disperse | distributed in water so that the content rate of the synthetic smectite 100 which concerns on this embodiment may be 2 mass% is 5000 mPa * s or less. When the viscosity of the dispersion exceeds 5000 mPa · s, when the clay film is formed by removing the solvent from the dispersion by a method such as drying, the removal of the solvent becomes insufficient, and the flatness of the resulting clay film is lowered. Tend to. In addition, as a viscosity evaluation method, for example, a B-type viscometer can be preferably used.

  The synthetic smectite 100 according to the present embodiment preferably has film formability.

Examples of a method for forming the synthetic smectite 100 according to the present embodiment include the following methods. When the synthetic smectite 100 is mixed with a solvent containing water as a main component, the exchangeable cation ^{Xb +} between the layer structures adsorbs water molecules by hydrogen bonding force, and has a thickness of 0.5 to 1.5 nm and a width of 1. A particulate synthetic smectite 100 having a distribution of 0 to 500 nm is obtained, and a dispersion in which the particulate synthetic smectite 100 is dispersed can be obtained. After pouring this dispersion into a base material for molding, the solvent is separated and removed from the dispersion, and synthetic smectite particles are regularly laminated to obtain a film-like molded product. Examples of the method for separating and removing the solvent include drying or centrifugation. In order to obtain a film-like molded article in which synthetic smectites are regularly laminated, it is preferable to gradually separate and remove the solvent. That is, for example, when a film-like molded product is obtained by drying and removing the solvent, the solvent is preferably removed by drying in a temperature range of 20 ° C to 60 ° C, and the solvent is removed in a temperature range of 20 ° C to 50 ° C. It is more preferable to remove by drying, and it is further preferable to remove the solvent by drying in a temperature range of 25 ° C to 40 ° C.

  Moreover, the said base material for shaping | molding is not limited at all, Metal base materials, such as polymer base materials, such as a polypropylene and a Teflon (trademark), and a brass plate, can be used suitably.

  The film-like molded body obtained by forming the synthetic smectite 100 according to this embodiment has a sufficiently reduced sodium ion content and is sufficiently excellent in flexibility.

  It is preferable that the mandrel bending radius when the film-shaped molded body has a film thickness of 50 μm is 5 mm or less. In addition, the thickness of the film-like molded body can be adjusted by changing the amount of the dispersion used for film formation and the content of the synthetic smectite contained in the dispersion. Moreover, the mandrel bending radius of a film-form molded object can be measured using a commercially available mandrel measuring device, for example. Moreover, the film thickness of a film-form molded object can be measured using a micrometer, for example.

[Composite film]
By using the synthetic smectite 100 according to this embodiment, a composite film containing the synthetic smectite 100 and a polymer component can be obtained. That is, for example, a synthetic liquid smectite 100 according to the present embodiment is dispersed in a solvent containing water as a main component, and a mixed liquid in which a predetermined amount of a polymer component is mixed with the dispersion liquid. And a solvent is removed from the mixed solution by a method such as drying or centrifugation, whereby a composite film molded body in which a mixture of a particulate synthetic smectite and a polymer component is laminated can be obtained.

  When removing the solvent from the mixed solution by a method such as drying or centrifugation, it is preferable to gradually separate and remove the solvent. That is, for example, when obtaining a composite film molded body by drying, it is preferable to remove the solvent in a temperature range of 20 ° C to 60 ° C, more preferably to remove the solvent in a temperature range of 20 ° C to 50 ° C, 25 More preferably, the solvent is removed in a temperature range of from 40 ° C to 40 ° C.

  Moreover, the said base material for shaping | molding is not limited at all, Metal base materials, such as polymer base materials, such as a polypropylene and a Teflon (trademark), and a brass plate, can be used suitably.

  By using a composite film in which the polymer component is mixed with the synthetic smectite 100 according to the present embodiment, a film molded body further having characteristics derived from the polymer component can be obtained. Further, in order to make full use of the properties such as the flexibility of the clay film formed using the synthetic smectite 100 according to this embodiment and the polymer component, the content of the synthetic smectite 100 is determined as follows. It is preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more with respect to the mass.

  The polymer component used in the composite film according to this embodiment is preferably water-soluble. Since the composite film according to the present embodiment is obtained through a dispersion liquid in which a water-based solvent is dispersed, a water-soluble polymer component that can be uniformly mixed with water is preferably used. it can. Examples of such water-soluble polymer components include water-soluble nylon, ammonium polyacrylate, carboxymethyl cellulose ammonium, methyl vinyl ether and maleic anhydride copolymer, and the like.

  The composite film according to this embodiment preferably has a light transmittance of 80% or more at a wavelength of 550 nm when the film thickness is 30 μm. The film thickness of the composite film can be adjusted by changing the amount of the mixed solution poured into the molding substrate and the content of the synthetic smectite 100 and the polymer component contained in the mixed solution. The light transmittance at a wavelength of 550 nm can be measured using a turbidimeter, for example. Further, as a method for measuring the film thickness, for example, a micrometer can be used.

[Method for producing synthetic smectite]
In the method for producing the synthetic smectite 100 of this embodiment, first, a composite hydroxide slurry is obtained by mixing a solution containing silicon and aluminum and an alkali solution at a ratio satisfying the above formulas (1) to (4) ( First step). Subsequently, a composite hydroxide slurry, a solution containing an alkali metal or alkaline earth metal or a mixture thereof, and water are mixed at a ratio satisfying the above formulas (1) to (4) to prepare a precursor slurry. (Second step). Furthermore, the obtained precursor slurry is hydrothermally reacted to obtain a product slurry containing the synthetic smectite 100 (third step). Finally, after stirring the obtained product slurry, solid-liquid separation is performed to obtain the synthetic smectite 100 of the present embodiment (fourth step). Details of each step will be described below.

<First step>
First, an aqueous solution containing aluminum and an aqueous solution or alcohol solution containing silicon are mixed at a ratio satisfying the above formulas (1) to (4). Mixing can be performed, for example, by stirring.

  In addition, as aqueous solution containing aluminum, the aqueous solution containing 1 or more types chosen from the group which consists of aluminum nitrate, aluminum chloride, aluminum acetate, aluminum sulfate, aluminum oxide, and aluminum hydroxide can be used suitably. As the aqueous solution or alcohol solution containing silicon, an aqueous solution or alcohol solution containing at least one selected from the group consisting of tetramethylorthosilicate, tetraethylorthosilicate, colloidal silica, fumed silica, and amorphous silica can be suitably used. . Moreover, in order to make the content of sodium ions contained in the synthetic smectite 100 10 ppm or less, the purity of silicon and aluminum in all the metal elements in these aqueous solutions or alcohol solutions is 99.9 atomic% or more. It is preferable.

  Next, the obtained mixed solution and an alkaline aqueous solution are mixed to prepare a composite hydroxide slurry. At this time, an alkaline aqueous solution may be added to the mixed solution, or the mixed solution may be added to the alkaline solution. Examples of the alkaline aqueous solution include an aqueous potassium hydroxide solution and an aqueous ammonia solution, and an aqueous ammonia solution containing no metal ions is preferred. At this time, the amount of the alkaline aqueous solution is preferably adjusted so that the pH of the composite hydroxide slurry is 4.0 to 11.0, and is adjusted so that the pH is 4.5 to 10.5. It is more preferable. Moreover, it is preferable to wash the composite hydroxide slurry obtained by the above-mentioned operation with a method such as a filtration method or a centrifugal separation method.

<Second step>
The composite hydroxide slurry obtained in the first step described above, a solution containing alkali metal ions or alkaline earth metal ions or a mixture thereof, and water are mixed at a ratio satisfying the above formulas (1) to (4). Thus, a precursor slurry is produced.

  In addition, as a solution containing alkali metal ions or alkaline earth metal ions or a mixture thereof, from the group consisting of hydroxide, nitrate, acetate, carbonate, oxalate, chloride and fluoride of these metal ions An aqueous solution containing one or more selected ones can be suitably used. At this time, the pH of the precursor slurry is adjusted to 8.0 to 12.6 by adjusting the concentration of the aqueous solution containing alkali metal ions or alkaline earth metal ions or a mixture thereof and the amount of water mixed. It is preferable to set it to 8.5 to 12.4.

<Third step>
Subsequently, the precursor slurry obtained in the second step is subjected to a hydrothermal reaction using, for example, an autoclave, whereby a product slurry containing the synthetic smectite 100 can be obtained. At this time, the temperature range of the hydrothermal reaction is preferably 200 to 370 ° C, and more preferably 220 to 370 ° C.

<Fourth process>
Finally, the product slurry obtained in the third step is stirred and then subjected to solid-liquid separation to obtain a synthetic smectite 100 represented by the above formula (1) and having a sodium ion content of 10 ppm or less. Obtainable. At this time, the stirring speed is preferably 3000 rpm or more, and more preferably 4000 rpm or more. That is, when the stirring speed is less than 3000 rpm, the separation of impurities such as the amorphous smectite 100 having dispersibility in water and the amorphous component not dispersed in water tends to be insufficient. Further, the stirring time is preferably 5 minutes or more, and more preferably 10 minutes or more. When the stirring time is less than 5 minutes, separation of impurities such as amorphous smectite 100 having dispersibility in water and an amorphous component that is not dispersed in water tends not to sufficiently proceed.

Centrifugation can be suitably used for solid-liquid separation. At this time, the centrifugal acceleration during centrifugation is preferably 1.96 × 10 ⁴ m / s ² (2000 G) or more, more preferably 2.94 × 10 ⁴ m / s ² (3000 G) or more. preferable. When the centrifugal acceleration is less than 1.96 × 10 ⁴ m / s ² (2000 G), separation of impurities such as amorphous smectite 100 having dispersibility in water and amorphous components that are not dispersed in water becomes insufficient. There is a tendency. Further, the centrifugation time is preferably 5 minutes or more, and more preferably 10 minutes or more. If the centrifugation time is less than 5 minutes, the separation of impurities such as the synthetic smectite 100 having dispersibility in water and an amorphous component that does not disperse in water tends to not sufficiently proceed.

  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 an Example demonstrates this invention further in detail, this invention is not limited to these Examples.

[Example 1]
<Manufacture of synthetic smectite>
In Example 1, first, a synthetic smectite containing a component represented by Li ⁺ _0.7 Al _4.7 Si _7.3 O ₂₀ (OH) ₄ as a main component was produced by the following procedure. First, 12 ml of colloidal silica (manufactured by Sigma-Aldrich, SiO ₂ content: 50% by mass) was mixed with 2 ml of a 1N nitric acid aqueous solution and 24 g of distilled water to obtain a colloidal silica dispersion. In addition, 24.15 g of aluminum nitrate nonahydrate (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) is dissolved in 100 ml of distilled water, and then mixed with the colloidal silica dispersion to contain silicon and aluminum. A mixed solution was obtained. Next, 24.19 g of a 28% by mass aqueous ammonia solution was mixed with this mixed solution at a dropping rate of 6.0 ml / min to obtain a composite hydroxide slurry having a pH = 10.8.

  Subsequently, 0.37 g of lithium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., purity: 99.9% by mass) is mixed with the obtained composite hydroxide slurry, and distilled water is further mixed so that the total amount becomes 250 ml. Thus, a precursor slurry was obtained. In addition, pH of the obtained precursor slurry was 11.6.

  Next, the 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. The product slurry thus obtained was a white translucent gel.

The obtained product slurry was stirred at 3000 rpm for 5 minutes using a shaft generator (manufactured by ASONE), then solid-liquid separation was performed using a centrifugal separation method, and solid components were recovered to obtain a synthetic smectite. The centrifugal acceleration of the centrifugal separation method was 7.85 × 10 ⁴ m / s ² (8000 G), and the centrifugation time was 10 minutes.

<Preparation of synthetic smectite dispersed aqueous solution>
0.4 g of the obtained synthetic smectite is placed in a beaker, and distilled water (20 ° C.) is added thereto to make a total amount of 20 g, followed by stirring with a Teflon (registered trademark) rotor so that the content of the synthetic smectite is reduced. The dispersion was 2% by mass and the synthetic smectite was dispersed in water.

[Example 2]
Synthetic smectite and a 2% by mass synthetic smectite dispersion were obtained in the same manner as in Example 1 except that the hydrothermal reaction conditions of the precursor slurry were 350 ° C., 48 hours, and autogenous pressure.

[Example 3]
A synthetic smectite and a 2% by mass synthetic smectite dispersion were obtained in the same manner as in Example 1 except that the hydrothermal reaction conditions of the precursor slurry were set to 300 ° C. for 24 hours and an autogenous pressure.

[Example 4]
Lithium fluoride (made by Wako Pure Chemical Industries, Ltd., special grade) 0.23 g is mixed with the composite hydroxide slurry instead of lithium hydroxide, and Li ⁺ _0.7 Al _4.7 Si _7.3 O ₂₀ is mixed. A synthetic smectite and a 2% by mass synthetic smectite dispersion were obtained in the same manner as in Example 1 except that a synthetic smectite containing the component represented by (OH _0.3 F _0.7 ) ₄ as a main component was produced. It was.

[Example 5]
A synthetic smectite and a 2% by mass synthetic smectite dispersion were obtained in the same manner as in Example 4 except that the hydrothermal reaction conditions of the precursor slurry were set at 220 ° C. for 336 hours and an autogenous pressure.

[Comparative Example 1]

First, a synthetic smectite containing a component represented by Na ⁺ _0.7 Al _4.7 Si _7.3 O ₂₀ (OH) ₄ as a main component was produced. First, 130 ml of water is put into a 300 ml beaker, 21.46 g of No. 3 water glass (SiO ₂ content: 28% by mass) is dissolved, and 6 ml of 16 N nitric acid is added all at once with stirring to obtain a silicic acid solution. It was. Next, 15.87 g of aluminum chloride (manufactured by Wako Pure Chemical Industries, Ltd., purity: 98% by mass) was added to the silicic acid solution to prepare a mixed solution containing silicon and aluminum. This mixed solution was added dropwise to 100 ml of 2N sodium hydroxide solution over 5 minutes with stirring. The pH of the composite hydroxide slurry obtained at this time was 4.4.

  Subsequently, 0.35 g of sodium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., purity: 99.9% by mass) is mixed with the obtained composite hydroxide slurry, and distilled water is further mixed so that the total amount becomes 250 ml. Thus, a precursor slurry was obtained. In addition, pH of the obtained precursor slurry was 8.8.

  Next, the precursor slurry was charged into a stainless steel autoclave and subjected to hydrothermal reaction at 350 ° C. for 24 hours under the conditions of self-generated pressure. The product slurry thus obtained was a white slurry-like substance. The synthetic smectite contained in this product slurry was the synthetic smectite of Comparative Example 1.

  Without performing solid-liquid separation of the obtained product slurry, this product slurry was diluted with water to obtain a 2% by mass synthetic smectite dispersion.

[Comparative Example 2]
In place of sodium hydroxide, 0.37 g of lithium hydroxide (manufactured by Wako Pure Chemical Industries, Ltd., purity 99.9% by mass) is mixed with the composite hydroxide slurry, and Li ⁺ _0.7 Al _4.7 Si ₇ is mixed. _.3 Synthetic smectite of Comparative Example 2 and a 2% by weight synthetic smectite dispersion were prepared in the same manner as Comparative Example 1 except that synthetic smectite containing the component represented by O ₂₀ (OH) ₄ as a main component was produced. did. The resulting product slurry was a white slurry.

[Comparative Example 3]
The synthetic smectite obtained in Comparative Example 1 was ion exchanged according to the following procedure to prepare the synthetic smectite of Comparative Example 3 and a 2% by mass synthetic smectite dispersion.

  First, 2 g of the synthetic smectite obtained in Comparative Example 1 was placed in a beaker, 50 g of pure water (20 ° C.) was added thereto, and the mixture was stirred with a Teflon (registered trademark) rotor, whereby the synthetic smectite was dispersed in water. A dispersion was obtained. To this dispersion, 0.8 g of lithium hydroxide monohydrate was added and left at 25 ° C. in the air for 1 hour.

Thereafter, using a commercially available centrifuge, centrifugation was performed at a centrifugal acceleration of 1.96 × 10 ⁴ m / s ² (2000 G) for 10 minutes to remove the supernatant from the dispersion, and 50 g of pure water was added ( Centrifugation operation 1). This centrifugation operation 1 was repeated a total of three times to obtain a dispersion in which at least a part of sodium ions between the synthetic smectite layer structures was replaced with lithium ions.

Next, the supernatant was removed from the dispersion by centrifuging at a centrifugal acceleration of 1.96 × 10 ⁴ m / s ² (2000 G) for 10 minutes using the above-mentioned centrifuge, and 50 g of pure water was added again. (Centrifuge operation 2). This centrifugation operation 2 was repeated a total of 3 times to wash away excess lithium ions. Thereafter, the supernatant was removed from the dispersion under the above centrifugal separation conditions to obtain a synthetic smectite of Comparative Example 3. Further, 0.4 g of the obtained synthetic smectite was put in a beaker, and distilled water (20 ° C.) was added thereto to make a total amount of 20 g, followed by stirring with a Teflon (registered trademark) rotor to contain the synthetic smectite. The ratio was 2% by mass, and a dispersion liquid in which synthetic smectite was dispersed in water was obtained.

[Evaluation of synthetic smectite]
The sodium ion content of the synthetic smectite obtained in each example and each comparative example, the mass reduction rate when heated at 150 ° C. to 300 ° C., and the viscosity and film-forming property of the 2% by mass synthetic smectite dispersion are as follows. evaluated. Furthermore, the mandrel bending radius, which is an index of the flexibility of the synthetic smectite film-like molded product, was also evaluated by the following procedure. Moreover, the composite film containing the said synthetic smectite and a high molecular component was produced, and the film formability and light transmittance were evaluated in the following procedures.

<Sodium ion content>
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 the sodium ions were extracted by shaking for 24 hours at a shaking speed of 100 rpm. The extract was analyzed by ICP-AES method (manufactured by Seiko Instruments Inc., apparatus name: SPS-1500R), and the sodium ion content was quantified from the obtained peak count. The results are shown in Table 1. In this measurement method, the lower limit of detection of sodium ions is 1 ppm. Therefore, what is shown as 0 ppm in Table 1 means that the content of sodium ions is less than 1 ppm.

<Mass reduction rate during heating at 150 ° C. to 300 ° C.>
Measures the mass reduction rate at 150 ° C to 300 ° C when heated at a heating rate of 10 ° C / min in an air stream of 50 ml / min with TG-DTA (manufactured by Shimadzu Corporation, device name: DTG-60H) did. In addition, the result was shown in the mass% on the basis of the mass before temperature rising (Table 1).

<Viscosity of 2% by weight synthetic smectite dispersion>
The viscosity of 50 g of a 2% by mass synthetic smectite dispersion was measured with a B-type viscometer (manufactured by Toki Sangyo, apparatus name: TV-22). The results are shown in Table 1.

<Film forming properties>
After pouring 20 g of a 2% by weight dispersion liquid in which synthetic smectite is dispersed onto a 5.0 cm × 3.2 cm square polypropylene tray (manufactured by ASONE) and spreading it uniformly, a box dryer (manufactured by Koyo Thermo System Co., Ltd.) Using a device name: KLO-45M), the film was dried at 30 ° C. for 24 hours to remove moisture and obtain a film-like molded product. When the obtained film-like molded product has no cracks and a sheet-like solid is formed, the film formability is “Yes”, and when the film-shaped molded product is not formed, it is separated into powder or the like. The film forming property was judged as “None”. The results are shown in Table 1.

<Mandrel bending radius>
A film-like molded product having a film thickness of 50 μm obtained by forming a synthetic smectite film is wound around a mandrel test rod (Cortech Co., Ltd., device name: BD-2000), and the film-like molded product is cracked or cut. The smallest test bar radius (mandrel bend radius) that did not occur was determined. In addition, the film thickness of the film-shaped molded object was measured using the micrometer (the Mitutoyo company make, apparatus name: 2-10N). The results are shown in Table 1.

[Preparation of composite film of synthetic smectite and polymer component]
7.0 g of the obtained synthetic smectite was placed in a beaker, and distilled water (20 ° C.) was added thereto to make a total amount of 70 g, followed by stirring with a Teflon (registered trademark) rotor to disperse the synthetic smectite in water. A 10 mass% synthetic smectite dispersion was obtained.

  Next, 175 g of ethanol (manufactured by Wako Pure Chemical Industries, Ltd., reagent special grade), 8.75 g of water-soluble nylon (manufactured by Nagase ChemteX Corporation, Toresin, FS-350E5AS, nylon content 20% by mass) as a polymer component, The above 10% by mass synthetic smectite dispersion (70 g) was mixed and stirred for 10 minutes using a shaft generator to obtain a product (mixing operation).

  100 g of the product obtained by the above mixing operation is put into a stirring deaerator (made by Shinky Co., Ltd., apparatus name: Awatori Nertaro, AR100), stirred at a stirring speed of 2000 rpm for 10 minutes, and then defoamed at 2200 rpm for 10 minutes. (Defoaming operation).

  The product obtained by the above defoaming operation was poured onto a Teflon (registered trademark) base material having a square size of A4 and a depth of 1 mm, spread uniformly, and then dried in a dryer at 25 ° C. for 3 hours to obtain synthetic smectite and A composite film containing a polymer component was obtained.

<Film formability of composite film>
When the composite film has no cracks and a sheet-like solid is formed, the film formability is “Yes”, and when the sheet-like solid is not formed and is separated into a powder form, the film formability is “ "None". The results are shown in Table 1.

<Light transmittance of composite film>
The total light transmittance of the composite film having a thickness of 30 μm at a wavelength of 550 nm was measured using a turbidimeter (manufactured by Nippon Denshoku Industries Co., Ltd., product name: NDH5000). In addition, the film thickness of the composite film was measured using the micrometer (Mitutoyo company make, apparatus name: 2-10N). The results are shown in Table 1.

  Since the synthetic smectites of Comparative Examples 1 to 3 could not form a film-like molded product, the mandrel bending radius could not be measured. Moreover, since the synthetic smectites of Comparative Examples 1 to 3 could not form a composite film, the light transmittance could not be measured.

DESCRIPTION OF SYMBOLS 1 ... Octahedral sheet, 3 ... Tetrahedral sheet, 10 ... Layer structure, 100 ... Synthetic smectite, 200 ... Card house structure, ^{Xb +} ... Exchangeable cation.

Claims (11)

The main component is the following formula (1);
^{_{X b + a / b Al 4}} + a Si 8-a O 20 (OH 1-c F c) 4 ··· (1)
[Wherein, X ^{b +} represents an alkali metal ion or an alkaline earth metal ion, and a, b and c each represent a numerical value satisfying the following formulas (2) to (4).
0 <a <2 (2)
1 ≦ b ≦ 2 (3)
0 ≦ c ≦ 1 (4)]
A synthetic smectite having a sodium ion content of 10 ppm or less.   The synthesis | combination of Claim 1 whose mass decreasing rate when it heats up at 10 degrees C / min from 150 degreeC to 300 degreeC in dry air is 2-5 mass% on the basis of the mass before temperature rising. Smectite.   The synthetic smectite according to claim 1 or 2, wherein the dispersion has a viscosity of 2000 mPa · s or more when dispersed in water such that the content is 2% by mass.   The synthetic smectite according to any one of claims 1 to 3, which has film-forming properties.   The synthetic smectite according to any one of claims 1 to 4, wherein a mandrel bending radius of a film-like molded product having a film thickness of 50 µm made of only synthetic smectite is 5 mm or less.   A composite film containing the synthetic smectite according to any one of claims 1 to 5 and a polymer component.   The composite film according to claim 6, wherein the polymer component is water-soluble.   The composite film of Claim 6 or 7 whose light transmittance of wavelength 550nm is 80% or more in film thickness of 30 micrometers. A first step of mixing a solution containing silicon and aluminum and an alkaline solution to obtain a composite hydroxide slurry;
A second step of preparing a precursor slurry by mixing the composite hydroxide slurry, a solution containing alkali metal ions or alkaline earth metal ions, and water;
A third step of hydrothermally reacting the precursor slurry to obtain a product slurry;
After stirring the product slurry, the product slurry is subjected to solid-liquid separation, and the main component is represented by the following formula (1);
^{_{X b + a / b Al 4}} + a Si 8-a O 20 (OH 1-c F c) 4 ··· (1)
[Wherein, X ^{b +} represents an alkali metal ion or an alkaline earth metal ion, and a, b and c each represent a numerical value satisfying the following formulas (2) to (4).
0 <a <2 (2)
1 ≦ b ≦ 2 (3)
0 ≦ c ≦ 1 (4)]
And a fourth step of obtaining a synthetic smectite having a sodium ion content of 10 ppm or less. The silicon source is at least one selected from the group consisting of tetramethylorthosilicate, tetraethylorthosilicate, colloidal silica, fumed silica, and amorphous silica;
The aluminum source is at least one selected from the group consisting of aluminum nitrate, aluminum chloride, aluminum acetate, aluminum sulfate, aluminum oxide and aluminum hydroxide;
The alkali metal ion or alkaline earth metal ion source is selected from the group consisting of nitrates, acetates, carbonates, oxalates, chlorides, hydroxides and fluorides containing alkali metal ions or alkaline earth metal ions. The method for producing a synthetic smectite according to claim 9, wherein the synthetic smectite is one or more of the above. In the first step, the pH of the composite hydroxide slurry is 4.0 to 11.0,
The pH of the precursor slurry in the second step is 8.0 to 12.6,
In the third step, the precursor slurry is subjected to a hydrothermal reaction for 24 hours or more under an autogenous pressure condition of 200 to 370 ° C.
In the fourth step, the product slurry is solid-liquid separated by centrifugation.
The method for producing a synthetic smectite according to claim 9 or 10.

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