JP2008222514A - Strontium carbonate and method for producing the same - Google Patents

Abstract

Disclosed is a fine spherical strontium carbonate for producing fine needle-like, rod-like, or columnar strontium carbonate, and production of strontium carbonate capable of producing the spherical strontium carbonate efficiently and simply Providing a method.
Carbon dioxide gas derived from a carbon dioxide source is released into a gas phase in a closed system, and the carbon dioxide gas released into the gas phase is dissolved in a liquid containing an Sr ²⁺ ion source to produce carbon dioxide. The method for producing strontium is a method for producing strontium carbonate, wherein the liquid containing the Sr ²⁺ ion source contains alcohol, and the alcohol content is 90% by volume or more.
[Selection] Figure 1

Description

  The present invention relates to a fine spherical strontium carbonate and a method for producing strontium carbonate which can produce the strontium carbonate efficiently and simply.

  Conventionally, carbonates have been widely used in fields such as rubber, plastics, and papermaking, but in recent years, carbonates with high functionality have been developed one after another, depending on the particle shape and particle diameter. It is used for various purposes. Among these various uses, there is an application in which carbonate is dispersed in a polymer optical material and oriented, and the birefringence of the polymer optical material is controlled, and the carbonate used therein is a fine (˜100 nm) needle shape. It is preferable to take any one of a rod shape and a column shape.

  In order to produce such fine needle-like, rod-like or columnar strontium carbonate, it is effective to use fine (˜100 nm) spherical strontium carbonate as a seed crystal. Examples of the method for producing the fine spherical strontium carbonate include (1) a method of introducing carbon dioxide gas into a strontium hydroxide aqueous solution or suspension (see Patent Document 1), and (2) a strontium hydroxide solution. A method of adding carbon dioxide to form a reaction mixture, sending the reaction mixture to a continuously stirred reactor, and making carbonate fine (see Patent Document 2), (3) suspension of strontium hydroxide A method of adding an aqueous sodium carbonate solution (see Patent Document 3) and the like are mentioned, but it is currently desired to provide a method for producing a fine spherical strontium carbonate more simply and efficiently.

JP 2006-124198 A Japanese National Patent Publication No. 11-514961 JP 2006-169038 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention relates to a fine spherical strontium carbonate for producing strontium carbonate in any of a needle shape, a rod shape, and a column shape that can be used for birefringence control of a polymer optical material, and the carbonic acid carbonate. An object of the present invention is to provide a method for producing strontium carbonate capable of producing strontium efficiently and simply.

Means for solving the problems are as follows. That is,
<1> In a closed system, carbon dioxide gas derived from a carbon dioxide source is released into the gas phase, and the carbon dioxide gas released into the gas phase is dissolved in a liquid containing an Sr ²⁺ ion source to strontium carbonate. In the method of manufacturing
In the method for producing strontium carbonate, the liquid containing the Sr ²⁺ ion source contains alcohol, and the alcohol content is 90% by volume or more.
<2> The method for producing strontium carbonate according to <1>, wherein the carbonic acid source is either solid or gas.
<3> The method for producing strontium carbonate according to <2>, wherein the carbonate source is a solid, and the carbonate source is ammonium carbonate.
<4> The method for producing strontium carbonate according to any one of <1> to <3>, wherein the alcohol includes at least one selected from methanol, ethanol, and isopropyl alcohol.
<5> The method for producing strontium carbonate according to any one of <1> to <4>, wherein Sr ²⁺ ions and carbonate ions are reacted at 20 ° C. to 30 ° C. in a sealed container.
<6> A strontium carbonate produced by the method for producing strontium carbonate according to any one of <1> to <5>.
<7> The strontium carbonate according to <6>, which is spherical.
<8> The strontium carbonate according to any one of <6> to <7>, wherein an average equivalent circle diameter is 10 nm to 100 nm.
<9> The strontium carbonate according to any one of <6> to <8>, which is used as a seed crystal for producing strontium carbonate having any one of a needle shape, a rod shape, and a column shape.

  According to the present invention, a conventional problem can be solved, and a fine needle-like, rod-like, or columnar strontium carbonate that can be used for birefringence control of a polymer optical material is produced. And a method for producing strontium carbonate capable of producing the strontium carbonate efficiently and simply.

(Method for producing strontium carbonate and strontium carbonate)
In the method for producing strontium carbonate of the present invention, in a closed system, carbon dioxide gas derived from a carbon dioxide source is released into a gas phase, and the carbon dioxide gas released into the gas phase is liquid containing an Sr ²⁺ ion source. Dissolve in to produce strontium carbonate.
The strontium carbonate of the present invention is produced by the method for producing strontium carbonate of the present invention.
Hereinafter, the details of the strontium carbonate of the present invention will be clarified through the description of the method for producing strontium carbonate of the present invention.

-Liquid containing Sr2 ⁺ ion source-
The Sr ²⁺ ion source is not particularly limited as long as it contains Sr ²⁺ ions, and can be appropriately selected depending on the purpose. Examples thereof include Sr nitrate, chloride, and hydroxide. Among these, strontium hydroxide (Sr (OH) ₂ .8H ₂ O) is particularly preferable.
The liquid containing the Sr ²⁺ ion source is preferably a suspension containing alcohol and further containing water.
The alcohol content in the liquid containing the Sr ²⁺ ion source is 90% by volume or more, and may be 100% by volume. When the content of the alcohol is less than 90% by volume, there are cases where needle-like strontium carbonate particles are produced instead of being spherical.
There is no restriction | limiting in particular as said alcohol, Although it can select suitably according to the objective, For example, methanol, ethanol, isopropyl alcohol, etc. are mentioned. These may be used individually by 1 type and may use 2 or more types together.

-Carbonate source-
The carbonic acid source is not particularly limited as long as it generates carbon dioxide gas, and can be appropriately selected according to the purpose. However, the state is preferably either solid or gas, A carbonic acid source is particularly preferred.
The carbonic acid source of the solid is not particularly limited and may be appropriately selected depending on the purpose, for example, ammonium carbonate _{[(NH 4) 2 CO 3} ] is preferable.
Examples of the gaseous carbon dioxide source include carbon dioxide gas.

The method for releasing the carbon dioxide gas into the gas phase is performed in a closed system, specifically, in a sealed container.
The method for dissolving the carbon dioxide gas in the liquid containing the Sr ²⁺ ion source is not particularly limited and may be appropriately selected depending on the intended purpose. For example, the carbon dioxide gas is slowly diffused and dissolved. Is preferred.
Moreover, it is preferable that the liquid containing the Sr ²⁺ ion source and the carbonic acid source are accommodated in one sealed container.
There is no restriction | limiting in particular as an accommodation aspect in the said airtight container of the liquid containing the said Sr2 ⁺ ion source and the said carbonic acid source, Although it can select suitably according to the objective, For example, the said carbonic acid source is solid. In some cases, the solid carbonic acid source may be disposed on the bottom surface in the sealed container, attached to the side surface, or suspended from the top surface.

It is preferable that the closed container is provided so that the discharge pressure of the carbon dioxide gas can be controlled.
The control mode of the discharge pressure of the carbon dioxide gas is not particularly limited and may be appropriately selected depending on the purpose.For example, based on Henry's law, the liquid containing the Sr ²⁺ ion source may It is preferable that the discharge pressure of the carbon dioxide gas is set so that the carbon dioxide gas dissolves in a desired mass.

Next, as an example of the method for producing strontium carbonate of the present invention, a case where the carbonic acid source is a solid will be described. For example, as shown in FIG. 1, the liquid 2 containing the Sr ²⁺ ion source is placed in a (sealed) container 1 and placed together with the carbonic acid source 3 on the bottom surface in one sealed container 1 and accommodated. Then, carbon dioxide gas 4 is generated from the carbon dioxide source 3, and the carbon dioxide source 3 releases the carbon dioxide gas 4 into the gas phase in the sealed container 1. The carbon dioxide gas 4 released into the gas phase diffuses slowly and dissolves in the liquid 2 containing the Sr ²⁺ ion source. As a result, with the Sr ²⁺ ion in the liquid 2 containing the Sr ²⁺ ion source, the Sr ²⁺ ion source and the carbonate ion is reacted caused by carbon dioxide gas 4 that dissolved in the liquid 2 containing, the strontium carbonate spherical Manufactured.

Here, the synthesis reaction of strontium carbonate when the Sr ²⁺ ion source is Sr (OH) ₂ is shown below.
Carbonic acid ions (CO ₃ ²⁻ ) generated when the carbon dioxide gas dissolves in the liquid (aqueous solution) containing the Sr ²⁺ ion source and ionized strontium ions (Sr ²⁺ ) react as shown in the following formula (1). Then, strontium carbonate (SrCO ₃ ) as the carbonate is synthesized.
Sr ²⁺ + CO ₃ ²⁻ → SrCO ₃ Formula (1)

There is no restriction | limiting in particular as reaction temperature in the said synthesis reaction, According to the objective, it can select suitably, For example, although carbonate can be synthesize | combined from about room temperature to less than 50 degreeC, it is 20 to 30 degreeC. preferable.
There is no restriction | limiting in particular as reaction time, Although it can select suitably according to the objective, 15 minutes-360 minutes are preferable, and 30 minutes-240 minutes are more preferable.
In addition, it is preferable to perform the said synthesis reaction, stirring the liquid containing the said Sr2 ⁺ ion source, and it is preferable as stirring speed that it is 500 rpm-1,500 rpm.

-Physical properties of strontium carbonate-
The strontium carbonate produced by the method for producing strontium carbonate of the present invention is spherical, and the average equivalent circle diameter is preferably 10 nm to 100 nm, more preferably 20 nm to 30 nm. In some cases, the major axis of the needle-like particles obtained by growing spherical particles having an average equivalent circle diameter exceeding 100 nm as seed crystals becomes too large (major axis of 200 nm or more).
Here, the average equivalent circle diameter can be obtained by, for example, image analysis type particle size distribution measurement software “Mac-View” manufactured by Mountec Co., Ltd.

-Use-
Strontium carbonate produced by the method for producing strontium carbonate of the present invention is a fine spherical particle having an average equivalent circle diameter of 10 nm to 100 nm, and produces strontium carbonate having any one of a needle shape, a rod shape, and a column shape. It is suitable as a seed crystal, cathode ray tube glass, ferrite magnet, dielectric ceramic material for multilayer ceramic capacitor, etc., and in particular, a seed for producing strontium carbonate having any one of needle shape, rod shape, and column shape It is suitable as a crystal.

  The method for producing strontium carbonate in any of a needle shape, a rod shape, and a columnar shape by using the spherical strontium carbonate of the present invention as a seed crystal and growing the seed crystal is not particularly limited, The method for producing strontium carbonate can be appropriately selected according to the purpose. For example, the spherical strontium carbonate of the present invention is used as a seed crystal, and an aqueous solution containing urea, strontium hydroxide hydrate, and sodium hydroxide. And strontium carbonate is allowed to react at 90 ° C. for 120 minutes to grow strontium carbonate to produce strontium carbonate particles having any one of a needle shape, a rod shape, and a column shape.

The strontium carbonate having any one of a needle shape, a rod shape, and a columnar shape using the spherical strontium carbonate of the present invention as a seed crystal preferably has an aspect ratio of more than 1, more preferably 1.5 to 20, 1.5-8 are still more preferable.
The obtained strontium carbonate having any one of a needle shape, a rod shape, and a columnar shape has little orientation inside the molded product and exhibits isotropic properties, such as a plastic reinforcing material, friction material, heat insulating material, filter, etc. Useful. In particular, in a composite material subjected to deformation such as a stretched material, the strength and optical characteristics can be improved by orienting the particles.

Further, the obtained strontium carbonate having a needle shape, a rod shape, or a columnar shape is dispersed in a birefringent optical polymer, and subjected to a stretching treatment to combine the optical polymer bond chain and the carbonate. When oriented substantially parallel, the birefringence caused by the orientation of the bond chain of the optical polymer can be canceled by the birefringence of the carbonate.
There is no restriction | limiting in particular as said extending | stretching process, According to the objective, it can select suitably, For example, uniaxial stretching is mentioned. Examples of the uniaxial stretching method include stretching with a stretching machine to a desired stretching ratio while heating as necessary.

  As an example of the intrinsic birefringence of an optical polymer having birefringence, “Transparent Resin So far: The World of High-Performance Optical Materials that Challenge IT” (Fumio Ide, Industrial Research Committee, First Edition) p. 29, specifically, as shown in Table 2 below. From Table 2, it is recognized that many of the optical polymers have positive birefringence. Further, when strontium carbonate is used as the carbonate and added to, for example, polycarbonate as the optical polymer, the positive birefringence of the mixture can be canceled and not only zeroed, but also negative. For this reason, it can be suitably used for an optical component, in particular, an optical element in which deflection characteristics are important and high accuracy is required.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Example 1)
-Preparation of strontium carbonate crystals-
As shown in FIG. 1, 10 ml of a 0.01 M strontium hydroxide suspension prepared from Sr (OH) ₂ .8H ₂ O as a liquid containing an Sr ²⁺ ion source (1 ml of water: 9 ml of methanol as a solvent) was contained. A container 2 and a container 3 containing solid ammonium carbonate [(NH ₄ ) ₂ CO ₃ ] as a carbonic acid source were placed in the sealed container 1. Then, carbon dioxide gas was generated from solid ammonium carbonate [(NH ₄ ) ₂ CO ₃ ], diffused, and dissolved in the strontium hydroxide suspension. At this time, the strontium hydroxide suspension was stirred and reacted at a reaction temperature of 23 ° C. to 26 ° C. for 360 minutes to produce strontium carbonate crystals.
The obtained strontium carbonate crystal was taken out by centrifugation and observed with a transmission electron microscope (TEM). A TEM photograph at this time is shown in FIG. The obtained strontium carbonate crystal was spherical, and the average equivalent circle diameter measured as follows was 53.5 nm.

<Measuring method of average equivalent circle diameter>
The average equivalent circle diameter was measured using image analysis type particle size distribution measurement software “Mac-View” manufactured by Mountec Co., Ltd.

(Example 2)
-Preparation of strontium carbonate crystals-
In Example 1, a strontium carbonate crystal was produced in the same manner as in Example 1 except that 10 ml of the 0.01 M strontium hydroxide suspension was replaced with 0.5 ml of water and 9.5 ml of methanol.
The obtained strontium carbonate crystal was observed with a transmission electron microscope (TEM). A TEM photograph at this time is shown in FIG. The obtained strontium carbonate crystal was spherical, and the average equivalent circle diameter measured in the same manner as in Example 1 was 41.5 nm.

(Example 3)
-Preparation of strontium carbonate crystals-
In Example 1, strontium carbonate crystals were produced in the same manner as in Example 1 except that 10 ml of the 0.01 M strontium hydroxide suspension was replaced with 10 ml of methanol.
The obtained strontium carbonate crystal was observed with a transmission electron microscope (TEM). A TEM photograph at this time is shown in FIG. The obtained strontium carbonate crystal was spherical, and the average equivalent circle diameter measured in the same manner as in Example 1 was 47.4 nm.

(Comparative Example 1)
In Example 1, a strontium carbonate crystal was produced in the same manner as in Example 1 except that 10 ml of the 0.01 M strontium hydroxide suspension was replaced with 2.5 ml of water and 7.5 ml of methanol.
The obtained strontium carbonate crystal was observed with a transmission electron microscope (TEM). A TEM photograph at this time is shown in FIG. The obtained strontium carbonate crystals were acicular. The aspect ratio was 7.1.

(Comparative Example 2)
In Example 1, strontium carbonate crystals were produced in the same manner as in Example 1 except that 10 ml of the 0.01 M strontium hydroxide suspension was replaced with 2 ml of water and 8 ml of methanol.
The obtained strontium carbonate crystal was observed with a transmission electron microscope (TEM). A TEM photograph at this time is shown in FIG. The obtained strontium carbonate crystal was acicular and the aspect ratio was 5.8.

(Comparative Example 3)
In Example 1, a strontium carbonate crystal was produced in the same manner as in Example 1 except that 10 ml of the 0.01 M strontium hydroxide suspension was replaced with 1.5 ml of water and 8.5 ml of methanol.
The obtained strontium carbonate crystal was observed with a transmission electron microscope (TEM). A TEM photograph at this time is shown in FIG. The obtained strontium carbonate crystal was acicular and the aspect ratio was 4.6.

(Reference Example 1)
-Preparation of strontium carbonate crystals-
A spherical strontium carbonate crystal produced on a scale 10 times that of Example 1 (using 100 ml of 0.01 M strontium hydroxide suspension as a solution containing Sr ²⁺ ion source (10 ml of water: 90 ml of methanol as a solvent)) Removed by centrifugation.
The obtained spherical strontium carbonate crystal was used as a seed crystal and dispersed in 100 ml of an aqueous solution containing 12.12 g of urea, 0.664 g of strontium hydroxide octahydrate, and 3.2 g of sodium hydroxide. For 120 minutes to grow spherical strontium carbonate crystals.
The obtained strontium carbonate crystal was observed with a transmission electron microscope (TEM). A TEM photograph at this time is shown in FIG. The obtained strontium carbonate crystal was acicular and the aspect ratio was 3.6.

  The strontium carbonate produced by the method for producing strontium carbonate crystals of the present invention is spherical, and is suitable as a seed crystal for growing into strontium carbonate particles having any one of a needle shape, a rod shape, and a column shape. Needle-like, rod-like, or columnar strontium carbonate with the seed crystal grown is extremely transparent in the visible range and specific wavelength range, so it is used for optical filters, paints, fibers, cosmetics, lenses, etc. It can be widely used as a very useful material.

FIG. 1 is a conceptual diagram illustrating an example of the method for producing strontium carbonate of the present invention. FIG. 2 is an SEM photograph of the strontium carbonate crystal produced in Example 1. FIG. 3 is a SEM photograph of the strontium carbonate crystal produced in Example 2. 4 is a SEM photograph of the strontium carbonate crystal produced in Example 3. FIG. FIG. 5 is an SEM photograph of the strontium carbonate crystal produced in Comparative Example 1. FIG. 6 is an SEM photograph of the strontium carbonate crystal produced in Comparative Example 2. FIG. 7 is an SEM photograph of the strontium carbonate crystal produced in Comparative Example 3. FIG. 8 is an SEM photograph of the strontium carbonate crystal produced in Reference Example 1.

Explanation of symbols

DESCRIPTION OF ^SYMBOLS 1 Airtight container 2 Liquid containing Sr2 ⁺ ion source 3 Carbon dioxide source 4 Carbon dioxide gas

Claims (9)

Carbon dioxide gas derived from a carbon dioxide source is released into a gas phase in a closed system, and the carbon dioxide gas released into the gas phase is dissolved in a liquid containing an Sr ²⁺ ion source to produce strontium carbonate. In the method
A method for producing strontium carbonate, wherein the liquid containing the Sr ²⁺ ion source contains alcohol, and the alcohol content is 90% by volume or more.   The method for producing strontium carbonate according to claim 1, wherein the carbonic acid source is either solid or gas.   The method for producing strontium carbonate according to claim 2, wherein the carbonate source is a solid, and the carbonate source is ammonium carbonate.   The method for producing strontium carbonate according to any one of claims 1 to 3, wherein the alcohol contains at least one selected from methanol, ethanol and isopropyl alcohol. 5. The method for producing strontium carbonate according to claim 1, wherein Sr ²⁺ ions and carbonate ions are reacted at 20 ° C. to 30 ° C. in a sealed container.   A strontium carbonate produced by the method for producing strontium carbonate according to any one of claims 1 to 5.   The strontium carbonate according to claim 6, which is spherical.   The strontium carbonate according to any one of claims 6 to 7, wherein an average equivalent circle diameter is 10 nm to 100 nm.   The strontium carbonate according to any one of claims 6 to 8, which is used as a seed crystal for producing strontium carbonate having any one of a needle shape, a rod shape, and a column shape.