JP2015221729A - Tubular aluminum silicate and production method of tubular aluminum silicate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a tubular aluminum silicate in which aggregation of particles with one another is suppressed and which can easily be applied to respective fields.SOLUTION: A tubular aluminum silicate has an average particle diameter (D50) of 5-300 nm, which is measured by dynamic light scattering and the variation coefficient of the particle diameter of 35% or less. A production method of the tubular aluminum silicate has: a step to mix an inorganic silicic acid compound and an inorganic aluminum compound with each other and conduct hydrothermal treatment of the mixture; and a step to ultrafiltrate the mixed liquid obtained by the hydrothermal treatment. The hydrothermal treatment of the production method of the tubular aluminum silicate, conducts: a step to treat an inorganic silicon compound solution having an Si concentration of 4-10 mM with an ion exchanger and prepare an orthosilicic acid solution having electric conductivity of 5-15 μS/cm and pH of 3.5-7.5; and a step to mix the orthosilicic acid solution, an inorganic aluminum compound solution and urea or ammonia with one another, make pH be adjusted to 2.8-5.0 and subsequently conduct hydrothermal treatment for 3-120 hours.

Description

  The present invention relates to a tubular aluminum silicate and a method for producing a tubular aluminum silicate.

  Conventionally, imogolite is known as an aluminum silicate. Imogolite is a kind of natural clay component that appears in soils based on descending volcanic ejecta such as volcanic ash and pumice, and is a nano-sized tubular aluminum silicate. This tubular aluminum silicate has silicon (Si), aluminum (Al), oxygen (O) and hydrogen (H) as main constituent elements, and is composed of many ≡Si—O—Al≡ bonds. The shape is a nanotube-like structure having an outer diameter of 2.0 to 3.0 nm, an inner diameter of 0.5 to 1.5 nm, and a length of several tens of nm to several μm.

  Tubular aluminum silicate has a unique nano tube shape and its high specific surface area, water affinity, ion exchange capacity and material adsorption capacity. Various industrial uses such as a heat pump system heat exchange agent that produces a refrigerant using a carrier, a humidity control material, and a low-temperature heat source are expected.

  In such a tubular aluminum silicate, a technique for improving the affinity with water, the ion exchange ability, the substance adsorption property, etc. by defining the pore diameter and length within a predetermined numerical range has been proposed ( For example, see Patent Document 1).

JP 2004-59330 A

In the above prior art, the functionality is improved by defining the pore diameter and length, but the dispersibility of the tubular aluminum silicate is not considered. Without high dispersibility, the tubular aluminum silicate may aggregate when added to other members. When the particles are aggregated, the specific surface area of the tubular aluminum silicate is reduced, or the tubular aluminum silicate is unevenly filled in the other members, so that the catalyst, the adsorbent, When used in various fields such as ion exchange agents, optical materials, and film formation, the characteristics that can be expected as a tubular aluminum silicate may not be exhibited.
Generally, when improving the dispersibility of nanoparticles and fine particles, a method of adjusting the pH and charging the particle surface to electrostatically repel, a method of applying a surface treatment to increase steric hindrance and making the particles less accessible Further, a method using a dispersant such as a surfactant may be employed. If the dispersibility of the tubular aluminum silicate is improved by such a method, the treatment may be complicated or the functionality of the tubular aluminum silicate may be lowered, which is not preferable.

  Accordingly, an object of the present invention is to provide a tubular aluminum silicate that is easy to be used in various fields, in which aggregation of particles is suppressed, and a method for producing the same.

As a result of investigating the cause of the above-mentioned problems in order to solve the above-mentioned problems relating to the present invention, the present inventors have found that the average particle diameter (D50) measured by the dynamic light scattering method in tubular aluminum silicates Is 5 nm or more, the coefficient of variation of the particle diameter is 35% or less, and the uniformity of the particle diameter of the tubular aluminum silicate can be improved, so that the dispersibility of the particles can be improved. It was found that aggregation can be suppressed.
That is, the subject concerning this invention is solved by the following means.

In order to solve the above problems, according to one aspect of the present invention,
Provided is a tubular aluminum silicate having an average particle diameter (D50) measured by a dynamic light scattering method of 5 nm or more and a coefficient of variation of the particle diameter of 35% or less.

According to another aspect of the invention,
A method for producing tubular aluminum silicate from an inorganic raw material solution,
Mixing the inorganic silicate compound solution and the inorganic aluminum compound solution and subjecting them to hydrothermal treatment;
And a step of ultrafiltration of the mixed liquid obtained by the hydrothermal treatment. A method for producing a tubular aluminum silicate is provided.

ADVANTAGE OF THE INVENTION According to this invention, aggregation of particle | grains is suppressed and the tubular aluminum silicate which is easy to be used for each field | area, and its manufacturing method can be provided.
This can reduce the amount of partially agglomerated particles (aggregates) that cause aggregation of the tubular aluminum silicate and extremely small particles, This is thought to be because they are less likely to aggregate with each other.
Moreover, when it adds to another member by making an average particle diameter and a coefficient of variation into the said numerical range, it can be filled uniformly. This is because the aggregation is suppressed and the dispersibility is improved, and within the above numerical range, the particle shape is specified to some extent, for example, the aspect ratio of the particles is more than a certain value, and the particles are oriented. This is thought to be easier.
In addition, according to the production method of the present invention, it is possible to easily produce a tubular aluminum silicate having an average particle diameter and a coefficient of variation in the above numerical range.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" showing a numerical range is used by the meaning containing the numerical value described before and behind that as a lower limit and an upper limit.

《Tubular aluminum silicate》
The tubular aluminum silicate of the present invention is characterized in that the average particle diameter (D50) measured by the dynamic light scattering method is 5 nm or more and the coefficient of variation of the particle diameter is 35% or less.

  Further, when the short axis of the tubular aluminum silicate is a and the long axis is b, b / a is preferably 25 or more and 500 or less, and more preferably 25 or more and 100 or less. By setting b / a to 25 or more, the characteristics of the tubular aluminum silicate as a tubular structure can be more suitably exhibited. By setting b / a to 500 or less, tubular aluminum silicate A stable structure can be obtained without excessively increasing the length of the salt.

(1) Measurement of average particle diameter (D50) by dynamic light scattering method The average particle diameter of the tubular aluminum silicate of the present invention is measured by a dynamic light scattering method. In the present invention, the measurement by the dynamic light scattering method means that performed using a particle size distribution measuring apparatus based on the dynamic light scattering method.
The dynamic light scattering method is performed by irradiating laser light to particles dispersed in a solvent and observing the scattered light with a photon detector. Normally, particles dispersed in a solvent have a Brownian motion, but the movement of particles becomes slower as the particle size becomes larger, and becomes faster as the particle size becomes smaller. At this time, when the laser beam is irradiated to the particles having Brownian motion, fluctuations corresponding to the Brownian motion are observed from the scattered light from the particles. By observing this fluctuation, the autocorrelation function is obtained by the photon correlation method, the diffusion coefficient indicating the Brownian motion velocity can be obtained by using the cumulant method and the histogram method analysis, and further using the Stokes-Einstein equation. The average particle size and particle size distribution can be determined.

  Examples of the particle size distribution measuring apparatus based on the dynamic light scattering method include a zeta potential / particle size measurement system ELSZ-2, DLS-8 (manufactured by Otsuka Electronics Co., Ltd.), and dynamic light scattering particle size distribution measurement. Examples thereof include a device LB-550 (manufactured by Horiba, Ltd.), a zeta potential / particle diameter / molecular weight measuring device zeta sizer nano ZSP (manufactured by Spectris Co., Ltd.), and the like.

The average particle diameter of the tubular aluminum silicate of the present invention measured by a dynamic light scattering method is 5 nm or more. When the average particle size is 5 nm or more, particles having a small particle size can be prevented from being contained, and aggregation of particles can be suppressed.
Moreover, it is preferable that the average particle diameter measured by the dynamic light scattering method is 300 nm or less. As a result, it is possible to prevent the aggregation of particles and increase the particle diameter so as to prevent the aggregation of particles between the particles. Occurrence can be further effectively suppressed.

(2) Coefficient of variation of particle diameter The coefficient of variation (CV value) of the particle diameter of the tubular aluminum silicate of the present invention is obtained from the following formula.
CV value = standard deviation of particle size distribution / average particle size The standard deviation and average particle size of the particle size distribution can be obtained by measurement by the dynamic light scattering method.

  The variation coefficient of the particle diameter of the tubular aluminum silicate of the present invention is 35% or less. When the variation coefficient is 35% or less, it is possible to obtain a tubular aluminum silicate with little variation in particles and high uniformity. As a result, particles having a small particle diameter and aggregates having a large particle diameter can be prevented from being contained, and the occurrence of aggregation between particles can be suppressed.

  Thus, when the average particle diameter (D50) of the tubular aluminum silicate is 5 nm or more and the variation coefficient of the particle diameter is 35% or less, aggregation of particles is effectively suppressed, and the tubular aluminum silicate is effectively suppressed. When the acid salt is added to another member, it can be uniformly dispersed, and the characteristics inherent to the tubular aluminum silicate can be suitably exhibited.

  Hereinafter, a preferable production method for producing a tubular aluminum silicate having an average particle diameter (D50) measured by a dynamic light scattering method of 5 nm or more and a coefficient of variation of the particle diameter of 35% or less will be described. The method for producing the tubular aluminum silicate is not limited to this.

<< Method for producing tubular aluminum silicate >>
The method for producing a tubular aluminum silicate according to the present invention comprises a step of hydrothermal treatment by mixing an inorganic silicate compound solution and an inorganic aluminum compound solution (hydrothermal treatment step), and a mixture obtained by hydrothermal treatment. And an ultrafiltration step (recovery step). By ultrafiltration of the liquid mixture obtained by hydrothermal treatment, unreacted substances, water and the like can be removed, and a tubular aluminum silicate with a high uniformity of particle diameter can be produced. For this reason, it is possible not to include particles having a small particle diameter or aggregates having a large particle diameter in which the particles are aggregated, and the aggregation of the particles is suppressed, so that the tubular aluminum silica that can be easily applied to each field is used. Acid salts can be provided.

(1) Hydrothermal treatment step In the hydrothermal treatment step, by treating an inorganic silicon compound solution having a Si concentration of 4 to 10 mM with an ion exchanger, the electrical conductivity is 5 to 15 µS / cm and the pH is 3.5 to 7.5. A first step of preparing an orthosilicate solution and a second step of hydrothermal treatment for 3 to 120 hours after mixing the prepared orthosilicate solution, inorganic aluminum compound solution and urea or ammonia to adjust the pH to 2.8 to 5.0 Are preferably performed.

In this case, since the orthosilicic acid solution is prepared by treating the inorganic silicon compound solution with the ion exchanger in the first step, the orthosilicic acid solution can be prepared in a high yield and in a short time. For this reason, a tubular aluminum silicate can be produced in a high yield and in a short time by performing the second step using the orthosilicate solution.
Further, in the first step, by setting the Si concentration of the inorganic silicon compound solution to 4 to 10 mM, it is possible to suppress the generation of polysilicic acid from silicic acid during ion exchange, and to obtain a tubular aluminum silicate with higher yield. Can be manufactured.
Further, in the second step, an orthosilicate solution, an inorganic aluminum compound solution and urea or ammonia are mixed and adjusted to pH 2.8 to 5.0, followed by heating for 3 to 120 hours, thereby generating by-products. Therefore, tubular aluminum silicate can be produced with higher yield. When urea is used, the thermal decomposition of urea can be promoted to improve the synthesis rate of the tubular aluminum silicate, and the tubular aluminum silicate can be efficiently obtained in a short time. Therefore, productivity can be improved. Furthermore, when urea is used, the length of the formed tubular aluminum silicate can be adjusted accurately by adjusting other various conditions as appropriate, so that the uniformity of each particle can be improved. it can.

(1.1) First Step In the first step, an electric conductivity of 5 to 15 μS / cm, pH 3.5 to an ion exchange treatment of an inorganic silicon compound solution having a Si concentration of 4 to 10 mM with an ion exchanger. It is preferred to prepare a 7.5 orthosilicate solution.
In order to synthesize tubular aluminum silicate, orthosilicic acid is required as a raw material, but orthosilicic acid is generally not distributed and is difficult to obtain. By performing the first step, orthosilicic acid can be easily prepared.

(Inorganic silicon compound solution)
The silicon source constituting the inorganic silicon compound solution is not particularly limited as long as silicate ions are generated when solvated. Examples of such a silicon source include sodium orthosilicate, sodium metasilicate, potassium metasilicate, and water glass.

  As the solvent, a solvent that can easily be solvated with the raw material silicic acid source can be appropriately selected and used. Specifically, water, alcohols, etc. can be used, for example. From the viewpoint of salt solubility and ease of handling during heating, water is preferably used.

  Moreover, it can suppress that polysilicic acid produces | generates from silicic acid at the time of ion exchange by using the inorganic silicon compound solution whose Si concentration is 4-10 mM.

(Ion exchanger)
As the ion exchanger used for the ion exchange treatment of the inorganic silicon compound solution, an anion exchanger or a cation exchanger is used. Examples of the anion exchanger include an anion exchange membrane and the like, and examples of the cation exchanger include a cation exchange resin and a cation exchange membrane. It is preferable to use a cation exchange resin because it is high and silicon concentration control is easy. Specifically, any conventionally known ion exchanger can be used as long as the orthosilicic acid solution obtained after the treatment can have an electric conductivity of 5 to 15 μS / cm and a pH of 3.5 to 7.5. May be used.

  As the cation exchange resin, either a strong acid cation exchange resin or a weak acid cation exchange resin may be used, or a plurality of cation exchange resins may be used in combination.

  Examples of the strongly acidic cation exchange resin include Amberlite IR120B (manufactured by Organo), Amberlite IR124 (manufactured by Organo), Amberlite 200CT (manufactured by Organo), Amberlite 252 (manufactured by Organo), Diaion SK104. (Mitsubishi Chemical Corporation), Diaion SK110 (Mitsubishi Chemical Corporation), Diaion SK112 (Mitsubishi Chemical Corporation), Diaion PK212 (Mitsubishi Chemical Corporation), Diaion PK216 (Mitsubishi Chemical Corporation), Diaion PK228 (Mitsubishi Chemical), Diaion UBK08 (Mitsubishi Chemical), Diaion UBK10 (Mitsubishi Chemical), Diaion UBK12 (Mitsubishi Chemical), Diaion UBK510L (Mitsubishi Chemical), Diaion UBK530 (Mitsubishi Chemical Corporation), Diaion U K550 (manufactured by Mitsubishi Chemical Corporation) and the like, but not limited thereto.

  Examples of the weak acid cation exchange resin include Amberlite FPC3500 (manufactured by Organo), Amberlite IRC76 (manufactured by Organo), Diaion WK10 (manufactured by Mitsubishi Chemical), Diaion WK11 (manufactured by Mitsubishi Chemical), Dia Examples include, but are not limited to, ion WK100 (manufactured by Mitsubishi Chemical Corporation) and diamond ion WK40L (manufactured by Mitsubishi Chemical Corporation).

  When ion exchange resin is used, as a method of ion exchange treatment of the inorganic silicon compound solution, for example, a batch method or a column method is used.

  In the case of the batch method, a conditioned ion exchange resin is put into a container, an inorganic silicon compound solution whose concentration is adjusted is added thereto, and the reaction is performed for about 2 hours while stirring or shaking at a strength that allows the ion exchange resin to float. Thereafter, the ion exchange resin is filtered off, and the filtrate is recovered to obtain an orthosilicate solution. If a magnetic stirrer is used, depending on the type of ion exchange resin, the ion exchange resin may be destroyed. Therefore, it is desirable to perform shaking during mixing. Here, conditioning means returning the ion exchange resin to a state where the ion exchange ability can be exhibited.

  In the case of the column method, an ion-exchange resin that has been conditioned is packed into a column, an inorganic silicon compound solution whose concentration is adjusted is flowed into the column at a constant flow rate, and the solution that flows out of the column is recovered to obtain an orthosilicate solution. obtain.

In the case of the batch method, the electric conductivity of the resulting orthosilicate solution can be adjusted by the degree of stirring or shaking, the reaction time, etc. In the case of the column method, the flow rate of the sample flowing in the column, the volume of the column ( Radius, length, etc.), the amount of ion-exchange resin filling, and the like. That is, the electrical conductivity of the orthosilicate solution can be adjusted by appropriately changing the contact time and the contact area between the inorganic silicon compound solution and the ion exchanger.
The pH of the resulting orthosilicate solution can be adjusted by the type of ion exchange resin used, the contact time between the ion exchange resin and the inorganic silicon compound solution, and the like. Specifically, when a cation exchange resin is used, the pH of the orthosilicate solution obtained becomes lower as the ion exchange proceeds. Therefore, when a strongly acidic cation exchange resin having a high ion exchange rate is used, the pH of the orthosilicate solution is increased. The pH of the orthosilicic acid solution remains high when a weakly acidic cation exchange resin with a lower ion exchange rate is used.

In the present invention, as described above, an ion exchange membrane may be used as the ion exchanger. The ion exchange membrane is an ion filtration membrane formed by molding an ion exchange resin into a film shape, and has a property of blocking the passage of ions having different signs and allowing only ions having the same sign to pass.
When an ion exchange membrane is used, it is preferable to use an anion exchange membrane and a cation exchange membrane together, but each may be used alone by combining with other methods.
The anion exchange membrane is positively charged because the cation group is fixed to the membrane, and only the anion is allowed to pass through without repelling the cation. Such anion exchange membranes are used, for example, for seawater concentration salt production, concentration / removal of metal ions, removal of radioactive ions / substances, and the like. By using such an anion exchange membrane, only the anion in the inorganic silicon compound solution can be permeated to prepare a target orthosilicate solution.
The cation exchange membrane is negatively charged because the anion group is fixed to the membrane, and only the cation is allowed to pass without repelling the anion.

(PH of orthosilicate solution)
The treatment conditions with the ion exchanger are preferably set so that the pH of the orthosilicic acid solution prepared by the treatment with the ion exchanger is 3.5 to 7.5. When the pH is 7.5 or less, it is possible to suppress the formation of polysilicic acid by polymerization of orthosilicic acid in the solution, and when the pH is 3.5 or more, the pH adjustment in the second step The amount of alkali added in can be reduced.

  The pH can be measured by a pH meter using a general glass electrode. Specifically, for example, MODEL (F-71S) (Horiba, Ltd.) can be used. The pH of the orthosilicate solution is as follows: phthalate pH standard solution (pH: 4.01), neutral phosphate pH standard solution (pH: 6.86), and borate pH standard solution (pH: 9.01). 18) is used as a pH standard solution, the pH meter is calibrated at three points, the electrode of the pH meter is placed in an orthosilicic acid solution, and the value after 5 minutes has elapsed and is read is read. At this time, the liquid temperature of the pH standard solution and the orthosilicate solution can be set to 25 ° C., for example.

(Electric conductivity σ of orthosilicate solution)
The treatment conditions with the ion exchanger are preferably set such that the electrical conductivity of the orthosilicic acid solution prepared by the treatment with the ion exchanger is 5 to 500 μS / cm. In particular, when ion exchange treatment is performed by a column method using a cation exchange resin, it is possible to adjust the electrical conductivity by adjusting the flow rate of the column. The electric conductivity of the orthosilicate solution is preferably 5 to 100 μS / cm, more preferably 5 to 15 μS / cm.
When the electrical conductivity of the orthosilicate solution is 500 μS / cm or less, the mixing of the salt into the mixed solution prepared in the second step is suppressed, and a tubular aluminum silicate can be produced with a high yield. . Moreover, the treatment time by an ion exchanger can be shortened and productivity can be improved as the electrical conductivity of an orthosilicic acid solution is 10 microsiemens / cm or more.

  Since the electrical conductivity of theoretical pure water is an insulator of about 0.055 μS / cm, it can be said that the electrical conductivity is an index indicating the total amount of ions in the solution, particularly when the solvent of the orthosilicate solution is water.

  The electrical conductivity of the orthosilicic acid solution can be measured with a general electrical conductivity meter, and specifically, for example, it is measured at room temperature (25 ° C.) using ES-51 (Horiba, Ltd.).

(1.2) Second Step In the second step, it is preferable to mix an orthosilicic acid solution, an inorganic aluminum compound solution and urea or ammonia and adjust the pH to 2.8 to 5.0, followed by hydrothermal treatment for 3 to 120 hours. .
In the second step, the element molar ratio Si / Al of the mixed solution obtained by mixing the orthosilicate solution and the inorganic aluminum compound solution is preferably 0.3 to 1.0. Thus, in the second step, the composition ratio of the tubular aluminum silicate to be produced can be changed by adjusting the element molar ratio Si / Al of the mixed solution. By setting the element molar ratio Si / Al within this range, the target tubular aluminum silicate can be obtained with high purity, and the production of by-products such as boehmite, gibbsite, amorphous silica and allophane is suppressed. be able to.

(Inorganic aluminum compound solution)
The aluminum source constituting the inorganic aluminum compound solution is not particularly limited as long as aluminum ions are generated when solvated. Examples of such an aluminum source include aluminum chloride, aluminum perchlorate, aluminum nitrate, and aluminum sec-butoxide.

  As the solvent, a solvent that can easily be solvated with the aluminum source as a raw material can be appropriately selected and used. Specifically, water, alcohols, etc. can be used, for example. From the viewpoint of salt solubility and ease of handling during heating, water is preferably used.

(Urea or ammonia)
Either urea or ammonia may be used, and it is preferable from the viewpoint of handleability to add as a solution adjusted to a predetermined concentration. In particular, when urea is used, the length of the formed tubular aluminum silicate can be accurately adjusted by appropriately adjusting other various conditions, so that the uniformity of each particle can be improved. it can.

(Adjusting the pH of the mixture)
In the second step, it is preferable to adjust the mixed solution obtained by mixing the orthosilicic acid solution, the inorganic aluminum compound solution, and urea or ammonia to pH 2.8 to 5.0. In order to adjust the pH to the range, for example, a method of adding a basic solution such as an aqueous sodium hydroxide solution or an aqueous potassium hydroxide solution, or a method of adding an acidic solution such as hydrochloric acid, acetic acid or nitric acid, etc. Can be mentioned.

(Hydrothermal treatment)
In the second step, hydrothermal treatment is performed on the mixed solution after pH adjustment. Although the heating temperature at this time is not specifically limited, It is preferable that it is 80-120 degreeC from a viewpoint of obtaining higher purity tubular aluminum silicate.
There exists a tendency which can suppress precipitation of the boehmite (monohydric aluminum oxide) which is a by-product as heating temperature is 120 degrees C or less. When urea is used, if the heating temperature is too high, rapid thermal decomposition may occur at the beginning of heating, and the ammonia concentration in the mixed solution may rise rapidly, causing the pH to approximate the alkaline side. It is thought that it is unsuitable for manufacture of the tubular aluminum silicate formed in the property-weak acidity.
Further, when the heating temperature is 80 ° C. or higher, the thermal decomposition of urea and the subsequent synthesis rate of the tubular aluminum silicate are improved, and the productivity can be improved.

  The heating time is preferably 3 to 120 hours. By setting the heating time to 3 hours or more, a tubular aluminum silicate having an average particle diameter (D50) of 5 nm or more can be formed with higher accuracy. In addition, by setting the heating time to 120 hours or less, a tubular aluminum silicate having an average particle diameter (D50) of 300 nm or less can be formed with higher accuracy. Can be done efficiently.

(2) Recovery process In the manufacturing method of the tubular aluminum silicate of the present invention, unreacted substances, water, and the like are removed from the mixed liquid obtained in the hydrothermal treatment process described above to obtain the tubular aluminum silicate. A recovery process is performed to separate and recover. In the production method of the present invention, the recovery step is performed by ultrafiltration.

(Ultrafiltration)
Ultrafiltration is a type of filtration, also called UF (Ultrafiltration) from the English initials, and is mainly used for concentration or diafiltration of soluble polymers such as proteins, DNA, starch, and natural or synthetic polymers Is done. The pore size of the ultrafiltration membrane is larger than the reverse osmosis membrane (RO membrane, NF membrane) and smaller than the microfiltration membrane (MF membrane). When the pore size is difficult to measure, the separation ability of the membrane is not based on the pore size, but is based on the blocking rate of proteins and dextran whose molecular weight is obvious. Nominal Molecular. Weight Limit ”or“ Molecular Weight Cut Off ”(MWCO).

The ultrafiltration is performed by a tangential flow filtration method (cross flow method) or a total amount filtration method. For most applications, ultrafiltration is carried out in a tangential flow filtration fashion, where molecules smaller than the pore size of the membrane are permeated (filtrate) and the rest (filtrate) as the feed liquid passes through the membrane surface. Retentate) remains without passing through the membrane. The advantage of using the tangential flow filtration method is that the fluid always flows over the entire surface of the membrane, so the formation of gel layer and cake layer on the surface of the membrane and its vicinity is suppressed, which ensures stable permeate volume and removal performance. It is easy to obtain and the lifetime of a film | membrane is extended.
As a tangential flow filtration method, Vivaflow 50 ultrafiltration concentrator VF05P9 (MWCO: 3000), VF05P1 (MWCO: 5000), VF05P0 (MWCO: 10,000), VF05C0 (MWCO: 10,000), VF05P2 (MWCO: 30000), VF05P3 (MWCO: 50000), VF05P4 (MWCO: 100000), VF05C4 (MWCO: 100000), VF05P6 (MWCO: 1000000), VF05P7 (pore diameter: 0.2 μm), Vivaflow 200 ultrafiltration concentrator VF20H9 (MWCO: 2000), VF20P9 (MWCO: 3000), VF20P1 (MWCO: 5000), VF20H1 (MWCO: 5000), VF20P1 (MWCO: 5000), VF20H1 (MWCO: 5000), VF20P0 (MWCO: 10000), VF20H0 (MWCO: 10000), VF20P2 (MWCO: 30000), VF20H2 (MWCO: 30000), VF20P3 (MWCO: 50000), VF20P4 (MWCO: 100000), VF20C40000 (MW) ), VF20P7 (pore diameter: 0.2 μm) (above, manufactured by Sartorius AG), tubular module MH25-NV-DUYM010 (MWCO: 20000), MH25-NV-DUYL010 (MWCO: 40000), MH25-NV-DUS0410 (MWCO: 40000), MH25-NV-DUS1010 (MWCO: 100000), 20100P18A (MWCO: 100000), 20100P18B (MWCO: 100,000), 20100P18LP (MWCO: 100,000) (above, manufactured by Daisen Membrane Systems Co., Ltd.) and the like, but are not limited thereto.

  Further, in the case of the total amount filtration method, the entire fluid flow is filtered through the filter, and any material that does not pass through the filter remains on the upper surface of the filter. For this reason, the film may be blocked in a short time due to the blocked fine particles and impurities.

  In the present invention, the ultrafiltration can be carried out by both the tangential flow filtration method and the total amount filtration method, but the tangential flow filtration method is desirable from the point of economical advantage because the filter is difficult to clog and the life of the membrane is extended.

As conditions for performing ultrafiltration, the solid content concentration of the liquid mixture obtained by hydrothermal treatment is 1 to 20%, the pH is 3 to 8, and the electrical conductivity (salt concentration) is 10 to 5000 μS / cm. Furthermore, it is more preferable that the solid content concentration of the mixed solution is 1 to 5%, the pH is 3 to 5, and the electric conductivity (salt concentration) is 10 to 200 μS / cm. Thereby, the dispersibility of the tubular aluminum silicate is improved in the mixture obtained by hydrothermal treatment, the average particle size (D50) is 5 nm or more, and the variation coefficient of the particle size is 35% or less. Tubular aluminum silicate can be obtained more reliably.
Moreover, in the manufacturing method of this invention, it is good also as what performs ultrafiltration in multiple times using the ultrafiltration membrane from which a hole diameter differs. For example, after removing particles having a large particle size using an ultrafiltration membrane having a large pore size, particles having a small particle size may be removed using an ultrafiltration membrane having a small pore size. Thereby, a tubular aluminum silicate having an average particle diameter (D50) of 5 nm or more and a coefficient of variation of the particle diameter of 35% or less can be obtained more reliably.

(3) Others The method for producing the tubular aluminum silicate of the present invention may have further steps such as solvent replacement and powder drying, if necessary.

  In the production method of the present invention, the tubular aluminum silicate is recovered by ultrafiltration. The average particle size (D50) is 5 nm or more, and the variation coefficient of the particle size is 35%. The method for obtaining the following tubular aluminum silicate is not limited to this method, and the tubular aluminum silicate may be recovered by salting out. However, from the viewpoint of obtaining a more uniform tubular aluminum silicate, it is preferable to perform the recovery step by ultrafiltration.

  When tubular aluminum silicate is recovered by salting out from a mixture obtained by hydrothermal treatment, an aqueous NaCl solution is added as a flocculant to gel the mixture, and this is centrifuged. Tubular aluminum silicate can be recovered. In order to obtain the tubular aluminum silicate of the present invention described above, it is necessary to adjust the concentration and addition amount of the NaCl aqueous solution added as a flocculant as appropriate. If the concentration and addition amount of the NaCl aqueous solution are too large, the tubular aluminum silicate is agglomerated too much, and a tubular aluminum silicate having a coefficient of variation of particle diameter of more than 35% is obtained. If the concentration and the amount added are too small, the tubular aluminum silicate is hardly agglomerated, and the tubular aluminum silicate cannot be obtained even by centrifugation.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto. Further, in the examples, “part” or “%” is used, but “part by mass” or “% by mass” is expressed unless otherwise specified.

<< Preparation of Sample 1 >>
First, sodium orthosilicate was dissolved in ion-exchanged water to prepare 10 L of a sodium orthosilicate aqueous solution having a Si concentration of 3.0 mM. The prepared sodium orthosilicate aqueous solution was introduced into a cation exchange resin packed in a column and subjected to ion exchange treatment to obtain a 3.0 mM orthosilicate aqueous solution. The flow rate of the column was set so that the electrical conductivity of the resulting orthosilicate aqueous solution was 500 μS / cm or less. In addition, the electrical conductivity of the orthosilicate aqueous solution was measured at 25 ° C. using an electrical conductivity meter ES-51 (manufactured by Horiba, Ltd.). Further, as the cation exchange resin, Amberlite IR120B (manufactured by Organo Co., Ltd.), which is a strongly acidic cation exchange resin, was used so that the pH of the orthosilicate aqueous solution was 5.0. The pH of the orthosilicate aqueous solution was measured by the above method using MODEL (F-71S) (Horiba, Ltd.).

  Next, 5 L of the obtained 3.0 mM orthosilicate aqueous solution, 1 L of 30 mM aluminum nitrate aqueous solution, 1 L of 28 mM urea aqueous solution, 1 L of 3.8 mM NaOH aqueous solution, and 2 L of ion-exchanged water were mixed, and Si A liquid mixture having a molar ratio of Al and Al of 1: 2 was prepared. Further, 4M NaOH aqueous solution was added dropwise so that the pH of the mixed solution was 3.5. The pH of the prepared mixed solution was measured by the same method as described above. After fully stirring the prepared liquid mixture, this liquid mixture was hydrothermally treated by heating at 100 ° C. for 3 hours in an autoclave (hydrothermal treatment step).

  After the mixture returned to room temperature, it was ultrafiltered using a Vivaflow 200 ultrafiltration concentrator VF20H9 (MWCO: 2000, manufactured by Sartorius AG), concentrated 100 times, and adjusted to pH 3.5 with nitric acid. Washing was performed using ion-exchanged water until the electric conductivity of the filtered effluent became 200 μS / cm or less to obtain an aqueous dispersion of tubular aluminum silicate (recovery step).

<< Preparation of Sample 2 >>
In the preparation of Sample 1, an aqueous dispersion of tubular aluminum silicate was obtained in the same manner except that ultrafiltration was performed using a Vivaflow 200 ultrafiltration concentrator VF20P4 (MWCO: 100,000, manufactured by Sartorius AG). It was.

<< Preparation of Sample 3 >>
In the preparation of Sample 1, the heating time in the autoclave was changed to 24 hours, and the same was performed except that ultrafiltration was performed using a Vivaflow 200 ultrafiltration concentrator VF20P0 (MWCO: 10,000, manufactured by Sartorius AG). An aqueous dispersion of tubular aluminum silicate was obtained.

<< Preparation of Sample 4 >>
In the preparation of Sample 1, the heating time in the autoclave was changed to 24 hours, and the same was performed except that ultrafiltration was performed using a Vivaflow 200 ultrafiltration concentrator VF20P9 (MWCO: 3000, manufactured by Sartorius AG). An aqueous dispersion of tubular aluminum silicate was obtained.

<< Preparation of Sample 5 >>
In the preparation of Sample 1, tubular aluminum silicate was used in the same manner except that the heating time in the autoclave was changed to 60 hours and ultrafiltration was performed using a Vivaflow 200 ultrafiltration concentrator VF20P0 (MWCO: 10000). An aqueous dispersion of salt was obtained.

<< Preparation of Sample 6 >>
In the preparation of Sample 1, the heating time in the autoclave was changed to 60 hours, and the same was performed except that ultrafiltration was performed using a Vivaflow 200 ultrafiltration concentrator VF20P2 (MWCO: 30000, manufactured by Sartorius AG). An aqueous dispersion of tubular aluminum silicate was obtained.

<< Preparation of Sample 7 >>
In the preparation of Sample 1, the heating time in the autoclave was changed to 120 hours, and the same was performed except that ultrafiltration was performed using a Vivaflow 200 ultrafiltration concentrator VF20P3 (MWCO: 50000, manufactured by Sartorius AG). An aqueous dispersion of tubular aluminum silicate was obtained.

<< Preparation of Sample 8 >>
In the preparation of Sample 1, the heating time in the autoclave was changed to 120 hours, and the same was performed except that ultrafiltration was performed using a Vivaflow 200 ultrafiltration concentrator VF20P4 (MWCO: 100,000, manufactured by Sartorius AG). An aqueous dispersion of tubular aluminum silicate was obtained.

<< Preparation of Sample 9 >>
First, a 1.5 mM orthosilicate aqueous solution was prepared in the same manner as in the preparation of Sample 1.
Next, 5 L of the obtained 1.5 mM orthosilicic acid aqueous solution and 5 L of 3.0 mM aluminum nitrate aqueous solution were mixed to prepare a mixture so that the molar concentration of Si and Al was 1: 2. . While thoroughly stirring the prepared mixed solution, 100 mM sodium hydroxide aqueous solution was added at a rate of 0.5 mL / min until pH 5.0, and the mixture was hydrothermally treated by heating at 100 ° C. for 3 hours in an autoclave.

  After the mixture returns to room temperature, it is ultrafiltered using a Vivaflow 200 ultrafiltration concentrator VF20P3 (MWCO: 50000), concentrated 100 times, and ion-exchanged water adjusted to pH 3.5 with nitric acid is used. Then, washing was carried out until the electric conductivity of the filtered waste liquid became 200 μS / cm or less to obtain an aqueous dispersion of tubular aluminum silicate.

<< Preparation of Sample 10 >>
In the preparation of Sample 9, a tube-shaped aluminum silicate dispersion was prepared in the same manner except that the heating time in the autoclave was changed to 6 hours and the collection step by ultrafiltration was performed as follows. .

  After the liquid mixture obtained in the hydrothermal treatment step returns to room temperature, the filtrate is recovered by ultrafiltration using a Vivaflow 200 ultrafiltration concentrator VF20P0 (MWCO: 10000) as a first separation operation, Further, as a second separation operation, ultrafiltration using a Vivaflow 200 ultrafiltration concentrator VF20H9 (MWCO: 2000) was concentrated 100 times, and ion exchange water adjusted to pH 3.5 with nitric acid was used. Washing was carried out until the electrical conductivity of the filtered effluent became 200 μS / cm or less to obtain an aqueous dispersion of tubular aluminum silicate.

<< Preparation of Sample 11 >>
In the preparation of sample 9, except that the heating time in the autoclave was changed to 48 hours, and ultrafiltration was performed using a Vivaflow 200 ultrafiltration concentrator VF20H9 (MWCO: 2000), tubular aluminum silicate An aqueous dispersion of salt was obtained.

<< Preparation of Sample 12 >>
In the preparation of sample 10, the heating time in the autoclave was changed to 120 hours, and the Vivaflow 200 ultrafiltration concentrator VF20P4 (MWCO: 100000) was used for the first separation operation, and Vivaflow was used for the second separation operation. An aqueous dispersion of tubular aluminum silicate was obtained in the same manner except that 200 ultrafiltration concentrator VF20P3 (MWCO: 50000) was used.

<< Preparation of Sample 13 >>
In the preparation of sample 10, the heating time in the autoclave was changed to 120 hours, and further, a Vivaflow 200 ultrafiltration concentrator VF20P7 (pore size: 0.2 μm, manufactured by Sartorius AG) was used for the first separation operation. An aqueous dispersion of tubular aluminum silicate was obtained in the same manner except that the Vivaflow 200 ultrafiltration concentrator VF20P3 (MWCO: 50000) was used for the second separation operation.

<< Preparation of Sample 14 >>
In the preparation of Sample 1, an aqueous dispersion of tubular aluminum silicate was obtained in the same manner except that the recovery step was changed to the following method.
That is, after the liquid mixture obtained in the hydrothermal treatment step returns to room temperature, a transparent tube is obtained by adding 1/10 volume of 5M NaCl aqueous solution as a flocculant to the liquid mixture, gelling, and centrifuging. A gel of aluminum silicate was obtained. NaCl, which is a salt contained in the obtained gel, was removed using a dialysis membrane to obtain an aqueous dispersion of tubular aluminum silicate.

<< Preparation of Sample 15 >>
An aqueous dispersion of tubular aluminum silicate was obtained in the same manner as in the preparation of Sample 14, except that 1M NaCl aqueous solution as a flocculant was added to the mixture to make it gel.

<< Preparation of Sample 16 >>
In the preparation of Sample 14, an aqueous dispersion of tubular aluminum silicate was obtained in the same manner except that the heating time in the autoclave was changed to 36 hours.

<< Preparation of Sample 17 >>
In the preparation of Sample 14, an aqueous dispersion of tubular aluminum silicate was obtained in the same manner except that the heating time in the autoclave was changed to 60 hours.

<< Preparation of Sample 18 >>
In the preparation of Sample 14, an aqueous dispersion of tubular aluminum silicate was obtained in the same manner except that the heating time in the autoclave was changed to 80 hours.

<< Preparation of Sample 19 >>
In the preparation of sample 14, the heating time in the autoclave was changed to 120 hours, and the tube was formed in the same manner except that 1M NaCl aqueous solution as a flocculant was added to the mixture to cause gelation. An aqueous dispersion of aluminum silicate was obtained.

<< Preparation of Sample 20 >>
Sample 14 was prepared in the same manner except that the heating time in the autoclave was changed to 120 hours and a 1M volume of 3M NaCl aqueous solution was added as a flocculant to the mixture to cause gelation. An aqueous dispersion of aluminum silicate was obtained.

<< Physical properties of tubular aluminum silicate samples 1 to 20 >>
Ion exchange water is added to the aqueous dispersion of tubular aluminum silicate obtained in the preparation of samples 1 to 20 to a solid content of 0.03%, and after 30 minutes of dispersion with an ultrasonic disperser, the particle size The average particle size (D50) was measured by a dynamic light scattering method using a zeta potential / particle size measurement system ELSZ-2 (manufactured by Otsuka Electronics Co., Ltd.) as a distribution measuring device. The measurement was performed 5 times for each sample, and the average value is shown in Table 1. In addition, Table 1 shows the coefficient of variation (CV value) of the particle diameter of each sample obtained from the obtained measurement results.

<< Evaluation of Tubular Aluminum Silicate for Samples 1-20 >>
The tubular aluminum silicate obtained in the preparation of samples 1 to 20 was evaluated as follows. The obtained evaluation results are shown in Table 1.

In addition, about evaluation of the following optical characteristics and film strength evaluation, the film containing the tubular aluminum silicate obtained by the preparation of Samples 1 to 20 was produced as follows, and the film was evaluated. went.
60.3 g of methyltrimethoxysilane, 40.0 g of methanol and 40.0 g of acetone were mixed and stirred. To the mixture was added 4.7 μL of a 60% nitric acid aqueous solution, and the mixture was stirred for 3 hours and further aged at 26 ° C. for 2 days. The obtained composition was diluted with methanol so that the polysiloxane solid content value was 10% by mass to obtain a polysiloxane solution. To 75 g of the polysiloxane solution, 25 g of the prepared 1% aqueous dispersion of tubular aluminum silicate was added and stirred to prepare a coating solution. The coating solution was spray-coated on a glass substrate to produce a film having a thickness of 50 μm on the glass substrate.

(1) Optical characteristic evaluation (transmittance measurement)
Based on Japanese Industrial Standard JISR3106 “Testing method of transmittance, reflectance, emissivity, and solar heat gain of flat glass”, visible light transmittance of each sample with spectrophotometer (U4100 manufactured by Hitachi High-Technologies Corporation) (Wavelength region 380-780 nm) was measured. About each, the transmittance | permeability of visible region was evaluated on the following reference | standard.
○: The transmittance when the glass plate is 100% is 98% or more Δ: The transmittance when the glass plate is 100% is 95% or more and less than 98% ×: The transmission when the glass plate is 100% Rate is less than 95%

(2) Film strength evaluation (crack resistance evaluation)
After the produced film was treated at 200 ° C. for 100 hours, the appearance was observed with a scanning electron microscope SEM (VE7800; manufactured by Keyence Corporation) at a magnification of 1000 times. About each, the presence or absence of the crack was evaluated on the following reference | standard.
A: The film does not have a crack with a length of 1 μm or more. ○: The film has one crack with a length of 1 μm or more and less than 10 μm. Δ: The film has one or more cracks with a length of 10 μm or more. : The film has 5 or more cracks with a length of 10 μm or more.

(3) Ion trap evaluation (migration evaluation)
An aqueous dispersion of tubular aluminum silicate composed of 1 part by mass of tubular aluminum silicate and 100 parts by mass of water was prepared, and 1000 parts by mass of ethanol was mixed to prepare a tubular aluminum silicate dispersion. A silicone resin layer in which the tubular aluminum silicate is dispersed is formed by mixing 100 parts by mass of the silicone resin with 100 parts by mass of the tubular aluminum silicate dispersion, dropping the mixture on a printed circuit board, and baking the mixture. Twenty printed boards were prepared.
The produced printed circuit board was continuously energized for 3000 hours in a constant temperature and humidity test tank at 85 ° C. and 85%. After this test, it was observed whether migration of the electrode portion occurred with a microscope, and the number of substrates on which migration occurred was evaluated according to the following criteria.
A: The number of substrates on which migration has occurred is 1 or 0. O: The number of substrates on which migration has occurred 2: Δ: The number of substrates on which migration has occurred 3: The number of substrates on which migration has occurred 4 More than

  From Table 1, the average particle size (D50) measured by the dynamic light scattering method is 5 nm or more, and the tubular aluminum silicate of the present invention having a particle size variation coefficient of 35% or less is the average particle size. Superior optical properties, film strength, and ion trap performance compared to the tubular aluminum silicate of the comparative example in which the diameter (D50) is not in the range of 5 nm or more and the variation coefficient of the particle diameter is not in the range of 35% or less. It can be seen that This is because the tube-shaped aluminum silicate has high uniformity, and particles containing small particles or aggregates that have been aggregated to increase the particle size are suppressed, so that aggregation of particles can be suppressed. it is conceivable that.

  Moreover, the tubular aluminum silicate of the samples 1-13 obtained by the manufacturing method of this invention is superior to the tubular aluminum silicate of the samples 14-20 obtained using salting out as a collection | recovery method. Performance. This is considered to be because when the tubular aluminum silicate is recovered by salting out, the tubular aluminum silicate needs to be aggregated to some extent by adding a flocculant.

  Further, in the hydrothermal treatment step, an orthosilicic acid solution having an electric conductivity of 5 to 15 μS / cm and a pH of 3.5 to 7.5 is prepared by treating an inorganic silicon compound solution having a Si concentration of 4 to 10 mM with an ion exchanger. Tube-like samples 1 to 8 that were subjected to a step of hydrothermal treatment for 3 to 120 hours after mixing the prepared orthosilicic acid solution, inorganic aluminum compound solution and urea and adjusting the pH to 2.8 to 5.0 The aluminum silicate shows performance superior to the tubular aluminum silicates of Samples 9 to 13 in which the hydrothermal treatment process was performed without adding urea. It is considered that the addition of urea makes it easier to obtain a tubular aluminum silicate having a uniform particle size.

Claims (4)

  A tubular aluminum silicate having an average particle diameter (D50) measured by a dynamic light scattering method of 5 nm or more and a coefficient of variation of the particle diameter of 35% or less.   The tubular aluminum silicate according to claim 1, wherein an average particle diameter (D50) measured by a dynamic light scattering method is 300 nm or less. A method for producing tubular aluminum silicate from an inorganic raw material solution,
Mixing the inorganic silicate compound solution and the inorganic aluminum compound solution and subjecting them to hydrothermal treatment;
And a step of ultrafiltering the liquid mixture obtained by the hydrothermal treatment. A method for producing a tubular aluminum silicate, comprising: In the hydrothermal treatment step,
A step of preparing an orthosilicate solution having an electrical conductivity of 5 to 15 μS / cm and a pH of 3.5 to 7.5 by treating an inorganic silicon compound solution having a Si concentration of 4 to 10 mM with an ion exchanger;
The step of hydrothermally treating for 3 to 120 hours after mixing the orthosilicic acid solution, the inorganic aluminum compound solution and urea or ammonia and adjusting the pH to 2.8 to 5.0 is performed. Method for producing tubular aluminum silicate.