JP2015145352A - Methacrylate crystal, and method of producing methacrylate crystal - Google Patents
Methacrylate crystal, and method of producing methacrylate crystal Download PDFInfo
- Publication number
- JP2015145352A JP2015145352A JP2014019314A JP2014019314A JP2015145352A JP 2015145352 A JP2015145352 A JP 2015145352A JP 2014019314 A JP2014019314 A JP 2014019314A JP 2014019314 A JP2014019314 A JP 2014019314A JP 2015145352 A JP2015145352 A JP 2015145352A
- Authority
- JP
- Japan
- Prior art keywords
- crystal
- methacrylic acid
- axis side
- growth rate
- ratio
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
Abstract
Description
本発明はメタクリル酸結晶、およびメタクリル酸結晶の製造方法に関する。 The present invention relates to methacrylic acid crystals and a method for producing methacrylic acid crystals.
例えば、イソブチレン、第３級ブチルアルコール、メタクロレインまたはイソブチルアルデヒドを分子状酸素により１段又は２段の反応で接触気相酸化して得られる生成物中には、目的物のメタクリル酸（沸点１６１℃／７６０ｍｍＨｇ、融点１５℃）の他に、例えば、ギ酸、酢酸、プロピオン酸、マレイン酸、シトラコン酸、安息香酸、トルイル酸、テレフタル酸、アクリル酸等のカルボン酸類や、ホルムアルデヒド、アセトアルデヒド、プロピオンアルデヒド、メタクロレイン、ベンズアルデヒド、トルアルデヒド、フルフラール等のアルデヒド類が副生成物として含まれている。これらの不純物の大部分は、抽出や蒸留等の通常の精製手段で分離精製が可能である。しかし、微量に含まれる不純物、例えば、アルデヒド類等を除去することは困難である。アルデヒド類は紫外部領域に吸収がみられるため、アルデヒド類が多く残存するメタクリル酸製品には着色が生じる場合がある。このような着色を回避するためには、アルデヒド類の残存量をできる限り低減することが求められる。 For example, in a product obtained by catalytic gas phase oxidation of isobutylene, tertiary butyl alcohol, methacrolein or isobutyraldehyde with molecular oxygen in a one-stage or two-stage reaction, the target methacrylic acid (boiling point 161) is obtained. In addition to carboxylic acids such as formic acid, acetic acid, propionic acid, maleic acid, citraconic acid, benzoic acid, toluic acid, terephthalic acid, acrylic acid, formaldehyde, acetaldehyde, propionaldehyde Aldehydes such as methacrolein, benzaldehyde, tolualdehyde and furfural are contained as by-products. Most of these impurities can be separated and purified by ordinary purification means such as extraction or distillation. However, it is difficult to remove impurities contained in a trace amount, such as aldehydes. Since aldehydes have absorption in the ultraviolet region, coloring may occur in methacrylic acid products in which a large amount of aldehydes remain. In order to avoid such coloring, it is required to reduce the residual amount of aldehydes as much as possible.
このような状況下において、蒸留法と比較してより高純度のメタクリル酸が得られる晶析法が検討されている。 Under such circumstances, a crystallization method capable of obtaining methacrylic acid of higher purity than the distillation method has been studied.
特許文献１には、粗製メタクリル酸に、第二成分としてメタノール、エタノール、プロパノールまたはブタノールを添加した溶液からメタクリル酸を晶析させ、析出した結晶と母液とを分離することによって、精製されたメタクリル酸を製造する方法が記載されている。 In Patent Document 1, methacrylic acid is crystallized from a solution in which methanol, ethanol, propanol or butanol is added as a second component to crude methacrylic acid, and the precipitated crystals and the mother liquor are separated to obtain purified methacrylic acid. A method for producing an acid is described.
一方、特許文献２には、４−ジメチルアミノ−Ｎ−メチル−４−スチルバゾリウムトシレートの単結晶形成において、溶液中の有機光学材料物質の濃度を変化させることによって単結晶の厚さやアスペクト比を制御する方法が記載されている。 On the other hand, in Patent Document 2, in the formation of a single crystal of 4-dimethylamino-N-methyl-4-stilbazolium tosylate, the thickness of the single crystal is changed by changing the concentration of the organic optical material substance in the solution. A method for controlling the aspect ratio is described.
また、特許文献３には、メタクリル酸の冷却晶析において、晶析原料の温度を固液平衡温度未満に下げた後、析出した結晶を含むスラリーの温度を固液平衡温度以上に上げ、保持した後、再度固液平衡温度未満に下げることで、懸濁結晶群の平均アスペクト比を低下させる方法が記載されている。 Further, in Patent Document 3, in cooling crystallization of methacrylic acid, the temperature of the crystallization raw material is lowered below the solid-liquid equilibrium temperature, and then the temperature of the slurry containing the precipitated crystals is raised to the solid-liquid equilibrium temperature or higher. After that, a method is described in which the average aspect ratio of the suspension crystal group is lowered by lowering again below the solid-liquid equilibrium temperature.
更に、特許文献４には、回分式冷却晶析において、冷却による結晶析出と加熱による結晶の一部溶解を繰り返すことによってより粗大な結晶を得る方法が記載されている。 Furthermore, Patent Document 4 describes a method of obtaining coarser crystals by repeating crystal precipitation by cooling and partial dissolution of crystals by heating in batch cooling crystallization.
しかしながら、特許文献１に記載の方法では、得られた結晶の形状が針状または柱状であり、アスペクト比が高い結晶が得られることが多い。ここでアスペクト比とは、結晶精製操作における、結晶の表面に付着した母液の洗浄性の指標で、長軸側結晶長を短軸側結晶長で除算した値であり、数値が高いほど結晶体積に対する表面積が大きく、洗浄性が低いと判断される。 However, in the method described in Patent Document 1, a crystal having a high aspect ratio is often obtained in which the obtained crystal has a needle shape or a column shape. Here, the aspect ratio is an index of the detergency of the mother liquor adhering to the crystal surface in the crystal refining operation, and is a value obtained by dividing the major axis side crystal length by the minor axis side crystal length. It is judged that the surface area is large and the detergency is low.
一方、特許文献２に記載の方法では、特定の原料溶液濃度、および結晶化条件を用いて結晶の形態を制御するが、対象物が４−ジメチルアミノ−Ｎ−メチル−４−スチルバゾリウムトシレートに限定されている。 On the other hand, in the method described in Patent Document 2, the crystal form is controlled by using a specific raw material solution concentration and crystallization conditions, but the object is 4-dimethylamino-N-methyl-4-stilbazolium. Limited to tosylate.
また、特許文献３に記載の方法は、懸濁結晶群のアスペクト比低下には一定の効果があるが、用いた種晶の結晶長やアスペクト比に関する記載はない。 Moreover, although the method described in Patent Document 3 has a certain effect in reducing the aspect ratio of the suspension crystal group, there is no description regarding the crystal length and aspect ratio of the seed crystal used.
特許文献４に記載の方法は、結晶スラリーの濾過性で評価される結晶の粗大化には効果があるが、結晶形状や結晶長、結晶アスペクト比に関する具体的な記載はない。 Although the method described in Patent Document 4 is effective in increasing the size of crystals evaluated by the filterability of the crystal slurry, there is no specific description regarding the crystal shape, crystal length, and crystal aspect ratio.
本発明は前記事情に鑑みてなされたものであり、良好な結晶表面洗浄性を有する、アスペクト比の低いメタクリル酸結晶、およびメタクリル酸結晶の製造方法を提供することを目的とする。 The present invention has been made in view of the above circumstances, and an object thereof is to provide a methacrylic acid crystal having a good crystal surface cleanability and a low aspect ratio, and a method for producing the methacrylic acid crystal.
本発明におけるメタクリル酸結晶、およびメタクリル酸結晶の製造方法は、
（１）長軸側結晶長が７０００μｍ以下の種晶を用い、長軸側結晶成長速度と短軸側結晶成長速度との比で定義される結晶成長速度比が、種晶のアスペクト比よりも小さくなる結晶成長操作により得られたメタクリル酸結晶である。
In the present invention, the methacrylic acid crystal, and the method for producing the methacrylic acid crystal,
(1) Using a seed crystal having a major axis side crystal length of 7000 μm or less, the crystal growth rate ratio defined by the ratio between the major axis side crystal growth rate and the minor axis side crystal growth rate is higher than the aspect ratio of the seed crystal. It is a methacrylic acid crystal obtained by a crystal growth operation that becomes smaller.
（２）長軸側結晶長が７０００μｍ以下の種晶を用い、長軸側結晶成長速度と短軸側結晶成長速度との比で定義される結晶成長速度比が、種晶のアスペクト比よりも小さくなる結晶成長操作によりメタクリル酸結晶を製造する方法である。 (2) Using a seed crystal having a major axis side crystal length of 7000 μm or less, the crystal growth rate ratio defined by the ratio between the major axis side crystal growth rate and the minor axis side crystal growth rate is higher than the aspect ratio of the seed crystal. This is a method for producing a methacrylic acid crystal by a crystal growth operation which becomes smaller.
（３）結晶を成長させる過程で、種晶のアスペクト比よりも小さい結晶成長速度比となるように固液平衡温度と溶液温度との差であるΔＴを制御する（２）のメタクリル酸結晶の製造方法である。 (3) In the process of growing the crystal, ΔT, which is the difference between the solid-liquid equilibrium temperature and the solution temperature, is controlled so that the crystal growth rate ratio is smaller than the aspect ratio of the seed crystal. It is a manufacturing method.
（４）前記ΔＴを０．０１〜５．０℃に制御する（３）に記載のメタクリル酸結晶の製造方法である。 (4) The method for producing a methacrylic acid crystal according to (3), wherein the ΔT is controlled to 0.01 to 5.0 ° C.
（５）（２）から（４）のいずれかに記載のメタクリル酸結晶を製造する方法において、結晶成長操作と結晶溶解操作を交互に繰り返して行うメタクリル酸結晶の製造方法である。 (5) In the method for producing a methacrylic acid crystal according to any one of (2) to (4), a method for producing a methacrylic acid crystal in which a crystal growth operation and a crystal dissolution operation are alternately repeated.
本発明によれば、良好な結晶表面洗浄性を有する、アスペクト比の低いメタクリル酸結晶、およびメタクリル酸結晶の製造方法を提供できる。
According to the present invention, it is possible to provide a methacrylic acid crystal having a good crystal surface cleanability and a low aspect ratio, and a method for producing a methacrylic acid crystal.
本発明におけるメタクリル酸結晶、およびメタクリル酸結晶の製造方法は、
（１）長軸側結晶長が７０００μｍ以下の種晶を用い、長軸側結晶成長速度と短軸側結晶成長速度との比で定義される結晶成長速度比が、種晶のアスペクト比よりも小さくなる結晶成長操作により得られたメタクリル酸結晶である。
In the present invention, the methacrylic acid crystal, and the method for producing the methacrylic acid crystal,
(1) Using a seed crystal having a major axis side crystal length of 7000 μm or less, the crystal growth rate ratio defined by the ratio between the major axis side crystal growth rate and the minor axis side crystal growth rate is higher than the aspect ratio of the seed crystal. It is a methacrylic acid crystal obtained by a crystal growth operation that becomes smaller.
（２）長軸側結晶長が７０００μｍ以下の種晶を用い、長軸側結晶成長速度と短軸側結晶成長速度との比で定義される結晶成長速度比が、種晶のアスペクト比よりも小さくなる結晶成長操作によりメタクリル酸結晶を製造する方法である。 (2) Using a seed crystal having a major axis side crystal length of 7000 μm or less, the crystal growth rate ratio defined by the ratio between the major axis side crystal growth rate and the minor axis side crystal growth rate is higher than the aspect ratio of the seed crystal. This is a method for producing a methacrylic acid crystal by a crystal growth operation which becomes smaller.
（３）結晶を成長させる過程で、種晶のアスペクト比よりも小さい結晶成長速度比となるように固液平衡温度と溶液温度との差であるΔＴを制御する（２）のメタクリル酸結晶の製造方法である。 (3) In the process of growing the crystal, ΔT, which is the difference between the solid-liquid equilibrium temperature and the solution temperature, is controlled so that the crystal growth rate ratio is smaller than the aspect ratio of the seed crystal. It is a manufacturing method.
（４）前記ΔＴを０．０１〜５．０℃に制御する（３）に記載のメタクリル酸結晶の製造方法である。 (4) The method for producing a methacrylic acid crystal according to (3), wherein the ΔT is controlled to 0.01 to 5.0 ° C.
（５）（２）から（４）のいずれかに記載のメタクリル酸結晶を製造する方法において、結晶成長操作と結晶溶解操作を交互に繰り返して行うメタクリル酸結晶の製造方法である。 (5) In the method for producing a methacrylic acid crystal according to any one of (2) to (4), a method for producing a methacrylic acid crystal in which a crystal growth operation and a crystal dissolution operation are alternately repeated.
本発明者らは鋭意検討を行った結果、結晶長軸、および結晶短軸を形成する結晶面の成長速度は、それぞれの結晶面の結晶長に依存しないこと、また、それぞれの結晶面の成長速度比、溶解速度比は固液平衡温度と溶液温度の差（ΔＴ）に依存することを見いだし、本発明を完成させるに至った。 As a result of intensive studies, the present inventors have found that the growth rate of the crystal plane forming the crystal major axis and the crystal minor axis does not depend on the crystal length of each crystal plane, and the growth of each crystal plane. It was found that the rate ratio and the dissolution rate ratio depend on the difference (ΔT) between the solid-liquid equilibrium temperature and the solution temperature, and the present invention has been completed.
以下に、本発明に係わる方法の実施形態について詳細を示すが、本発明はこれらに限定されるものではない。 Details of the embodiments of the method according to the present invention will be described below, but the present invention is not limited thereto.
本発明では、結晶の製造原料として、粗製メタクリル酸を用いる。 In the present invention, crude methacrylic acid is used as a raw material for producing crystals.
粗製メタクリル酸は、例えば直接酸化法やＡＣＨ法等の種々の方法により製造することができる。このような粗製メタクリル酸の製造方法としては、例えば以下に示す方法が挙げられる。イソブチレン、第３級ブチルアルコール、メタクロレインおよびイソブチルアルデヒドからなる群から選ばれる少なくとも１種の化合物を分子状酸素により１段又は２段の反応で接触気相酸化する直接酸化法で得られる反応ガスを凝縮して得た凝縮液、又は該反応ガスの凝縮液に水を加えるか、該反応ガスを水に吸収させて得たメタクリル酸水溶液から有機溶剤を用いてメタクリル酸を抽出し、蒸留により有機溶剤および不揮発分を除去して粗製メタクリル酸を得る方法が挙げられる。また、ＡＣＨ法で副生するメタクリル酸を抽出や蒸留により分離して粗製メタクリル酸を得る方法等が挙げられる。また、これらの方法によって得られた粗製メタクリル酸を、精密蒸留や晶析等の手法によって更に精製し、結晶の製造原料として用いても構わない。 Crude methacrylic acid can be produced by various methods such as a direct oxidation method and an ACH method. Examples of a method for producing such crude methacrylic acid include the following methods. A reaction gas obtained by a direct oxidation method in which at least one compound selected from the group consisting of isobutylene, tertiary butyl alcohol, methacrolein and isobutyraldehyde is subjected to catalytic gas phase oxidation with molecular oxygen in a one-stage or two-stage reaction. Methacrylic acid is extracted from the aqueous solution of methacrylic acid obtained by adding water to the condensate obtained by condensing the reaction gas or by condensing the reaction gas into water, and then extracted by distillation. A method for obtaining crude methacrylic acid by removing the organic solvent and non-volatile components is mentioned. Moreover, the method of isolate | separating the methacrylic acid byproduced by ACH method by extraction or distillation, and obtaining crude methacrylic acid etc. are mentioned. Further, the crude methacrylic acid obtained by these methods may be further purified by a technique such as precision distillation or crystallization and used as a raw material for producing crystals.
本発明に係る方法では、粗製メタクリル酸に１種又は２種以上の第二成分を添加した混合物を晶析原料として用いることが好ましい。 In the method according to the present invention, it is preferable to use a mixture obtained by adding one or more second components to crude methacrylic acid as a crystallization raw material.
第二成分としては、晶析の際にメタクリル酸と固溶体を形成しない物質であれば特に制限なく用いることができる。このような第二成分としては、例えば、メタノール、エタノール、プロパノール、ブタノール、ジエチルエーテル、ジオキサン、テトラヒドロフラン、アセトン、メチルエチルケトン、メチルイソブチルケトン、ギ酸メチル、ギ酸エチル、酢酸メチル、酢酸エチル、メタクリル酸メチル、メタクリル酸エチル、アクリル酸メチル、アクリル酸エチル、ヘキサン、流動パラフィン等が挙げられる。好ましくは、第二成分は、メタノール、エタノール、アセトン、ヘキサン、メタクリル酸メチルおよびアクリル酸メチルからなる群から選ばれる少なくとも一種である。第二成分としては、これらの物質を単独で用いることができ、２種以上を混合して用いることもできる。また、第二成分が原料である粗製メタクリル酸に含まれている場合は、新たに添加せず、そのまま使用することも可能である。 As the second component, any substance that does not form a solid solution with methacrylic acid during crystallization can be used without particular limitation. Examples of such second component include methanol, ethanol, propanol, butanol, diethyl ether, dioxane, tetrahydrofuran, acetone, methyl ethyl ketone, methyl isobutyl ketone, methyl formate, ethyl formate, methyl acetate, ethyl acetate, methyl methacrylate, Examples include ethyl methacrylate, methyl acrylate, ethyl acrylate, hexane, and liquid paraffin. Preferably, the second component is at least one selected from the group consisting of methanol, ethanol, acetone, hexane, methyl methacrylate and methyl acrylate. As the second component, these substances can be used alone, or two or more kinds can be mixed and used. In addition, when the second component is contained in the raw methacrylic acid, it can be used as it is without being newly added.
晶析原料に含まれる第二成分の濃度は０．１〜５０質量％であることが好ましく、０．１〜２０質量％であることがより好ましく、１〜１５質量％であることがさらに好ましい。第二成分の濃度が０．１質量％以上の場合、メタクリル酸の結晶が析出し始める温度、すなわち固液平衡温度と、メタクリル酸の凝固点との温度差を大きくでき、晶析操作を容易に行える。また、粗製メタクリル酸の固化も回避でき、晶析操作をスムースに行うことができる。一方、第二成分の濃度が５０質量％未満の場合、固液平衡温度が大幅に低下することなく晶析操作を行えるため、冷却するためのエネルギーコストを必要以上に上げることなく実施できる。 The concentration of the second component contained in the crystallization raw material is preferably 0.1 to 50% by mass, more preferably 0.1 to 20% by mass, and further preferably 1 to 15% by mass. . When the concentration of the second component is 0.1% by mass or more, the temperature difference between the temperature at which methacrylic acid crystals begin to precipitate, that is, the solid-liquid equilibrium temperature, and the freezing point of methacrylic acid can be increased, facilitating the crystallization operation. Yes. Moreover, solidification of the crude methacrylic acid can be avoided, and the crystallization operation can be performed smoothly. On the other hand, when the concentration of the second component is less than 50% by mass, the crystallization operation can be performed without drastically lowering the solid-liquid equilibrium temperature, so that the energy cost for cooling can be increased without being increased more than necessary.
第二成分の種類および濃度は、晶析操作時の操作性の観点から、第二成分添加後の粗製メタクリル酸の固液平衡温度が−１０〜１０℃の範囲になるように選択することが好ましく、−２〜１０℃の範囲になるように選択することがより好ましく、３〜１０℃の範囲になるように選択することがさらに好ましい。固液平衡温度は、既存の固液平衡データや実測により決定できる。 From the viewpoint of operability during the crystallization operation, the type and concentration of the second component may be selected so that the solid-liquid equilibrium temperature of the crude methacrylic acid after the addition of the second component is in the range of −10 to 10 ° C. Preferably, it is more preferably selected to be in the range of −2 to 10 ° C., and further preferably selected to be in the range of 3 to 10 ° C. The solid-liquid equilibrium temperature can be determined by existing solid-liquid equilibrium data or actual measurement.
次に、冷却式晶析槽を用いて晶析原料の晶析操作を行う。冷却式晶析槽としては、槽内に冷却用熱媒体を循環させる冷却コイルを有する冷却器、もしくは槽の周面に外側から冷却用熱媒体を接触させるための冷却ジャケットを有する冷却器とを備え、槽の周面を伝熱面として熱交換により槽内を冷却することができるものが好ましい。また、冷却コイルと冷却ジャケットを共に有する構成としてもよい。 Next, the crystallization raw material is crystallized using a cooling crystallization tank. As the cooling crystallization tank, a cooler having a cooling coil for circulating the cooling heat medium in the tank, or a cooler having a cooling jacket for bringing the cooling heat medium into contact with the peripheral surface of the tank from the outside. It is preferable that the inside of the tank can be cooled by heat exchange with the peripheral surface of the tank as the heat transfer surface. Moreover, it is good also as a structure which has both a cooling coil and a cooling jacket.
本発明では晶析槽内に仕込まれた晶析原料中へ種晶となるメタクリル酸結晶を投入する。 In the present invention, a methacrylic acid crystal serving as a seed crystal is charged into a crystallization raw material charged in a crystallization tank.
種晶を晶析槽内へ投入した後、冷却することでメタクリル酸結晶を成長させる。ここで、冷却器の温度は溶液のΔＴが種晶のアスペクト比よりも小さい結晶成長速度比となるΔＴになるよう設定する。結晶成長速度比とは結晶長軸側の成長速度を結晶短軸側の成長速度で除した値である。メタクリル酸結晶の場合、結晶成長速度、および結晶成長速度比は結晶長に依存しないことが参考例２の結果から明らかとなった。これは、晶析原料を一定のΔＴで保持した場合、結晶のアスペクト比は結晶成長速度比に漸近することを意味する。従って、ΔＴを種晶のアスペクト比よりも小さい結晶成長速度比となるΔＴになるよう設定することで、結晶の成長と共にアスペクト比が減少する。ΔＴの範囲は、０．０１〜５．０℃が好ましく、０．０５〜３．０℃がより好ましく、０．１〜０．５℃がさらに好ましい。０．０１℃以上では結晶成長速度が大きくなり、結晶の生産性に有利である。また、０．０１℃より低いと、精度の良い温度制御が実質的に困難である。一方、５．０℃以下では結晶の異常成長が起こりにくく、針状や柱状の結晶の一部分が突出し崩れた形状となり難い。結晶の異常成長が起こると、結晶表面に付着した母液の洗浄性に悪影響を与える可能性が高くなるため、結晶の異常成長は回避すべきである。 After putting the seed crystal into the crystallization tank, the methacrylic acid crystal is grown by cooling. Here, the temperature of the cooler is set so that the ΔT of the solution becomes ΔT at which the crystal growth rate ratio is smaller than the aspect ratio of the seed crystal. The crystal growth rate ratio is a value obtained by dividing the growth rate on the crystal major axis side by the growth rate on the crystal minor axis side. In the case of methacrylic acid crystals, the results of Reference Example 2 revealed that the crystal growth rate and the crystal growth rate ratio do not depend on the crystal length. This means that when the crystallization raw material is held at a constant ΔT, the crystal aspect ratio gradually approaches the crystal growth rate ratio. Therefore, by setting ΔT to be ΔT that is a crystal growth rate ratio smaller than the aspect ratio of the seed crystal, the aspect ratio decreases as the crystal grows. The range of ΔT is preferably 0.01 to 5.0 ° C, more preferably 0.05 to 3.0 ° C, and still more preferably 0.1 to 0.5 ° C. Above 0.01 ° C., the crystal growth rate increases, which is advantageous for crystal productivity. If it is lower than 0.01 ° C., accurate temperature control is substantially difficult. On the other hand, when the temperature is 5.0 ° C. or lower, abnormal crystal growth hardly occurs, and a part of a needle-like or columnar crystal does not easily protrude and collapse. If abnormal crystal growth occurs, there is a high possibility of adversely affecting the cleaning properties of the mother liquor adhering to the crystal surface, so abnormal crystal growth should be avoided.
用いる種晶としては長軸側結晶長が小さいものほど有利であり、長軸側結晶長が７０００μｍ以下の結晶を用いる。上述のとおり、結晶成長速度比は結晶長に依存しないため、この領域の結晶を用いることで効率的なアスペクト比の改善が図れる。このような種晶の取得方法としては、特許文献３や特許文献４記載の温度変調法が挙げられる。種晶の添加方法としては、事前に調整した種晶を晶析原料へ別途添加してもよいし、前述の温度変調法によって得られた結晶含有溶液をそのまま種晶が添加された晶析原料として用いてもよい。 As the seed crystal to be used, a crystal having a longer major axis side crystal length is more advantageous, and a crystal having a major axis side crystal length of 7000 μm or less is used. As described above, since the crystal growth rate ratio does not depend on the crystal length, the aspect ratio can be improved efficiently by using crystals in this region. Examples of such seed crystal acquisition methods include temperature modulation methods described in Patent Document 3 and Patent Document 4. As a seed crystal addition method, a seed crystal prepared in advance may be separately added to the crystallization raw material, or the crystal-containing solution obtained by the above-described temperature modulation method is directly added to the crystallization raw material. It may be used as
なお、結晶の各軸方向の長さは、カメラ等での撮影によって得られた結晶画像から長さを測定する、一般的な画像法により計測することができる。 Note that the length of each crystal in the axial direction can be measured by a general image method in which the length is measured from a crystal image obtained by photographing with a camera or the like.
晶析装置として冷却ジャケットや冷却コイルを備えた冷却式晶析槽を用いた場合、晶析槽内の溶液温度と冷却ジャケットおよび／または冷却コイル内熱媒体温度との差は１５℃以下であることが好ましく、１０℃以下であることがより好ましく、７℃以下であることがさらに好ましい。結晶析出温度と冷却ジャケットおよび／または冷却コイル内熱媒体温度との差を１５℃以下とすることにより、伝熱面での過飽和度が過剰とならず、伝熱面でのスケーリングの発生をより防止することができる。また、晶析槽内の溶液温度と冷却ジャケットおよび／または冷却コイル内熱媒体温度との差が小さすぎると伝熱面積を大きくしなければならなくなるため、０．５℃以上が好ましい。 When a cooling crystallization tank equipped with a cooling jacket or cooling coil is used as the crystallization apparatus, the difference between the solution temperature in the crystallization tank and the temperature of the cooling jacket and / or the heating medium in the cooling coil is 15 ° C. or less. It is preferably 10 ° C. or lower, more preferably 7 ° C. or lower. By setting the difference between the crystal precipitation temperature and the temperature of the heat medium in the cooling jacket and / or the cooling coil to 15 ° C. or less, the degree of supersaturation on the heat transfer surface does not become excessive, and the occurrence of scaling on the heat transfer surface is further increased. Can be prevented. Further, if the difference between the solution temperature in the crystallization tank and the temperature of the heat medium in the cooling jacket and / or the cooling coil is too small, the heat transfer area must be increased.
一方、特許文献３や特許文献４に記載のとおり、懸濁スラリー中結晶群の平均アスペクト比改善や平均結晶粒子径増加のため、スラリーを加熱し、微小結晶を消失させる操作を行うことがある。このような操作を鑑み、本発明では、溶液を加熱することでメタクリル酸結晶を溶解させる場合、通常の条件も同様に、長軸側結晶長が７０００μｍ以下の種晶を用いる。メタクリル酸結晶の場合、結晶融解速度、および結晶融解速度比は結晶長に依存しないことが参考例３の結果から明らかとなった。従って、種晶のアスペクト比が溶解速度比よりも小さい場合、この領域の結晶を用いることで、アスペクト比の改善が図れる。また、種晶のアスペクト比が溶解速度比よりも大きい場合でも、この領域の結晶を用いることで、アスペクト比の悪化を最小限に抑えることが可能となる。 On the other hand, as described in Patent Document 3 and Patent Document 4, in order to improve the average aspect ratio of the crystals in the suspended slurry and increase the average crystal particle size, the slurry may be heated to cause the microcrystals to disappear. . In view of such operations, in the present invention, when a methacrylic acid crystal is dissolved by heating the solution, a seed crystal having a major axis side crystal length of 7000 μm or less is similarly used under normal conditions. In the case of methacrylic acid crystals, the results of Reference Example 3 revealed that the crystal melting rate and the crystal melting rate ratio do not depend on the crystal length. Therefore, when the aspect ratio of the seed crystal is smaller than the dissolution rate ratio, the aspect ratio can be improved by using a crystal in this region. Even when the aspect ratio of the seed crystal is larger than the dissolution rate ratio, the deterioration of the aspect ratio can be minimized by using the crystal in this region.
以下、本発明について実施例を挙げて具体的に説明するが、本発明はこれら実施例に限定されるものではない。 EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated concretely, this invention is not limited to these Examples.
下記実施例および比較例において、晶析装置としては冷却ジャケットを備えたガラス製冷却式晶析槽（１０ｍＬ）を用い、回分式にて晶析操作を行った。冷却用熱媒体としては、エタブラインＥＣ−Ｚ（商品名、東京ファインケミカル（株）製）を用いた。冷却用熱媒体の温度制御には、ＮＴＢ−２２１（商品名、東京理化（株）製）を用いた。なお、冷却用熱媒体の流通量と比較して晶析槽の容量は少量であるため、晶析槽内の溶液温度として、冷却ジャケット内の冷却用熱媒体温度を採用した。
（実施例）
表１に示される不純物を含有する粗製メタクリル酸Ａと第二成分としてのメタノールとを混合し、メタノールを５．０質量％含む晶析原料を調製した。
In the following examples and comparative examples, a crystallization operation was performed batchwise using a glass cooling crystallization tank (10 mL) equipped with a cooling jacket as a crystallization apparatus. Etabline EC-Z (trade name, manufactured by Tokyo Fine Chemical Co., Ltd.) was used as the cooling heat medium. NTB-221 (trade name, manufactured by Tokyo Rika Co., Ltd.) was used for temperature control of the cooling heat medium. In addition, since the capacity | capacitance of a crystallization tank is small compared with the distribution | circulation amount of the cooling heat medium, the heat medium temperature for cooling in a cooling jacket was employ | adopted as the solution temperature in a crystallization tank.
(Example)
Crude methacrylic acid A containing impurities shown in Table 1 and methanol as the second component were mixed to prepare a crystallization raw material containing 5.0% by mass of methanol.
［参考例１］
ガラス製冷却式晶析槽に前記晶析原料を入れ、冷却用熱媒体を冷却ジャケットへ流通し、メタクリル酸結晶粒子群を析出させた。その後、ジャケットの温度を上昇させることによるメタクリル酸結晶粒子群の一部溶解、消失、ジャケットの温度を低下させることによる残存結晶の成長を行う温度変調法による結晶の消失、成長を繰り返したところ、晶析槽内のメタクリル酸結晶個数が数個になった。ここで、晶析槽内メタクリル酸結晶の結晶長が実質的に変化しなくなるよう、冷却用熱媒体温度を調整した。その際の晶析槽内容液温度は８．０７℃であった。この温度を固液平衡温度と定義した。
［参考例２］
続いて、参考例１で得られた長軸側結晶長３０３５μｍ、短軸側結晶長４６８μｍのメタクリル酸結晶を用い、各ΔＴ条件下における、測定開始時の結晶長を基準とした長軸側結晶成長量と短軸側結晶成長量の測定を行った。結晶長の測定は、カメラにより結晶の写真を撮り、測定した。それぞれの結果を図１、および図２に示す。それぞれのΔＴにおいて、グラフの傾きが一定であることから、長軸側、および短軸側のメタクリル酸結晶成長速度は結晶長に依存しないこと、また、ΔＴが大きいほど結晶成長速度は高くなることが明らかとなった。
［参考例３］
参考例２に引き続き、晶析槽内の溶液温度を固液平衡温度よりも高くし、各ΔＴ条件下における、測定開始時の結晶長を基準とした長軸側結晶溶解量と短軸側結晶溶解量の測定を行った。それぞれの結果を図３、および図４に示す。それぞれのΔＴにおいて、グラフの傾きが一定であることから、長軸側、および短軸側のメタクリル酸結晶溶解速度は結晶長に依存しないこと、また、ΔＴの絶対値が大きいほど結晶溶解速度は高くなることが明らかとなった。
[Reference Example 1]
The crystallization raw material was placed in a glass cooling crystallization tank, and a cooling heat medium was passed through the cooling jacket to precipitate a methacrylic acid crystal particle group. Then, the dissolution of the methacrylic acid crystal particle group by raising the temperature of the jacket, disappearance, the disappearance of the crystal by the temperature modulation method of growing the residual crystal by lowering the temperature of the jacket, repeated growth, The number of methacrylic acid crystals in the crystallization tank became several. Here, the temperature of the cooling heat medium was adjusted so that the crystal length of the methacrylic acid crystals in the crystallization tank was not substantially changed. The liquid temperature in the crystallization tank at that time was 8.07 ° C. This temperature was defined as the solid-liquid equilibrium temperature.
[Reference Example 2]
Subsequently, using the methacrylic acid crystal having a major axis side crystal length of 3035 μm and a minor axis side crystal length of 468 μm obtained in Reference Example 1, the major axis side crystal based on the crystal length at the start of measurement under each ΔT condition The growth amount and minor axis side crystal growth amount were measured. The crystal length was measured by taking a picture of the crystal with a camera. Each result is shown in FIG. 1 and FIG. Since the slope of the graph is constant at each ΔT, the methacrylic acid crystal growth rate on the long axis side and the short axis side does not depend on the crystal length, and the crystal growth rate increases as ΔT increases. Became clear.
[Reference Example 3]
Subsequent to Reference Example 2, the solution temperature in the crystallization tank is made higher than the solid-liquid equilibrium temperature, and the major-axis-side crystal dissolution amount and minor-axis-side crystal based on the crystal length at the start of measurement under each ΔT condition. The amount of dissolution was measured. Each result is shown in FIG. 3 and FIG. Since the slope of the graph is constant at each ΔT, the methacrylic acid crystal dissolution rate on the long axis side and the short axis side does not depend on the crystal length, and the crystal dissolution rate increases as the absolute value of ΔT increases. It became clear that it would be higher.
以上のデータを用い、各ΔＴ条件でのメタクリル酸結晶の結晶成長速度比、およびメタクリル酸結晶溶解速度比の算出を行った。結果を図５、図６に示す。図５より、メタクリル酸結晶成長速度比はΔＴが大きいほど高くなることがわかった。一方、図６より、ΔＴに対するメタクリル酸結晶溶解速度比の依存性は比較的小さいことが明らかとなった。 Using the above data, the crystal growth rate ratio of methacrylic acid crystals and the methacrylic acid crystal dissolution rate ratio under each ΔT condition were calculated. The results are shown in FIGS. FIG. 5 shows that the methacrylic acid crystal growth rate ratio increases as ΔT increases. On the other hand, FIG. 6 reveals that the dependence of the methacrylic acid crystal dissolution rate ratio on ΔT is relatively small.
［実施例１］
ガラス製冷却式晶析槽に前記メタクリル酸晶析原料を入れ、冷却用熱媒体を冷却ジャケットへ流通し、メタクリル酸結晶を析出させた。その後、温度変調法によるメタクリル酸結晶の消失、成長を繰り返したところ、晶析槽内のメタクリル酸結晶個数が１個になった。ここで、晶析槽内結晶のメタクリル酸結晶長が実質的に変化しなくなるよう、冷却用熱媒体温度を調整した。その際の晶析槽内容液温度は８．０８℃であった。この温度を固液平衡温度と定義した。
[Example 1]
The methacrylic acid crystallization raw material was placed in a glass cooling crystallization tank, and a cooling heat medium was passed through the cooling jacket to precipitate methacrylic acid crystals. Thereafter, when the disappearance and growth of the methacrylic acid crystals by the temperature modulation method were repeated, the number of methacrylic acid crystals in the crystallization tank became one. Here, the temperature of the cooling heat medium was adjusted so that the methacrylic acid crystal length of the crystals in the crystallization tank was not substantially changed. The liquid temperature in the crystallization tank at that time was 8.08 ° C. This temperature was defined as the solid-liquid equilibrium temperature.
このメタクリル酸結晶を種晶として利用し、溶液温度７．８８℃（ΔＴ＝０．２０℃）として約１００００秒結晶成長操作を行った。図５より、このΔＴ条件下における長軸と短軸のメタクリル酸結晶成長速度比は３〜４程度と予測された。種晶、および最終的に得られたメタクリル酸結晶の長軸側結晶長、メタクリル酸結晶アスペクト比、実際の長軸と短軸のメタクリル酸結晶成長速度比を表２に示す。
［実施例２］
次に実施例１で得られた溶液を加熱し、溶液温度８．４８℃（ΔＴ＝−０．４０℃）として約１８００秒結晶溶解操作を行った。図６より、このΔＴ条件下における長軸と短軸のメタクリル酸結晶溶解速度比は７〜８程度と予測された。種晶、および最終的に得られたメタクリル酸結晶の長軸側結晶長、メタクリル酸結晶アスペクト比、実際の長軸と短軸のメタクリル酸結晶溶解速度比を表３に示す。
［比較例１］
ガラス製冷却式晶析槽に前記晶析原料を入れ、冷却用熱媒体を冷却ジャケットへ流通し、メタクリル酸結晶粒子群を析出させた。その後、ジャケットの温度を上昇させることによるメタクリル酸結晶粒子群の一部溶解、消失、ジャケットの温度を低下させることによる残存結晶の成長を行う温度変調法による結晶の消失、成長を繰り返した。このとき、冷却速度と溶解速度を変化させ、長軸側結晶長が７７００μｍの結晶を得た。この結晶を種晶として用いたこと以外、実施例１と同様にしてメタクリル酸結晶成長操作を行った。図５より、このΔＴ条件下における長軸と短軸のメタクリル酸結晶成長速度比は３〜４程度と予測された。種晶、および最終的に得られたメタクリル酸結晶の長軸側結晶長、メタクリル酸結晶アスペクト比、実際の長軸と短軸のメタクリル酸結晶成長速度比を表２に示す。
［比較例２］
比較例１で得られた長軸側結晶長が１３０００μｍの結晶を種晶として使用したこと以外、実施例２と同様にしてメタクリル酸結晶溶解操作を行った。図６より、このΔＴ条件下における長軸と短軸のメタクリル酸結晶溶解速度比は７〜８程度と予測された。種晶、および最終的に得られたメタクリル酸結晶の長軸側結晶長、メタクリル酸結晶アスペクト比、実際の長軸と短軸のメタクリル酸結晶溶解速度比を表３に示す。
This methacrylic acid crystal was used as a seed crystal, and a crystal growth operation was performed for about 10,000 seconds at a solution temperature of 7.88 ° C. (ΔT = 0.20 ° C.). From FIG. 5, the ratio of the growth rate of methacrylic acid crystals between the long axis and the short axis under this ΔT condition was predicted to be about 3-4. Table 2 shows the seed crystal and the crystal length of the methacrylic acid crystal finally obtained, the crystal length of the methacrylic acid crystal, the aspect ratio of the methacrylic acid crystal, and the actual methacrylic acid crystal growth rate ratio between the major axis and the minor axis.
[Example 2]
Next, the solution obtained in Example 1 was heated, and a crystal dissolution operation was performed at a solution temperature of 8.48 ° C. (ΔT = −0.40 ° C.) for about 1800 seconds. From FIG. 6, it was estimated that the ratio of dissolution rate of methacrylic acid crystals between the major axis and the minor axis under this ΔT condition was about 7-8. Table 3 shows the seed crystal, the crystal length of the methacrylic acid crystal finally obtained, the crystal length of the methacrylic acid crystal, the aspect ratio of the methacrylic acid crystal, and the ratio of methacrylic acid crystals dissolved in the actual major and minor axes.
[Comparative Example 1]
The crystallization raw material was placed in a glass cooling crystallization tank, and a cooling heat medium was passed through the cooling jacket to precipitate a methacrylic acid crystal particle group. Thereafter, the dissolution and disappearance of the crystals by the temperature modulation method in which the methacrylic acid crystal particles were partially dissolved and disappeared by raising the jacket temperature and the remaining crystals were grown by lowering the jacket temperature were repeated. At this time, the cooling rate and the dissolution rate were changed to obtain a crystal having a major axis side crystal length of 7700 μm. A methacrylic acid crystal growth operation was performed in the same manner as in Example 1 except that this crystal was used as a seed crystal. From FIG. 5, the ratio of the growth rate of methacrylic acid crystals between the long axis and the short axis under this ΔT condition was predicted to be about 3-4. Table 2 shows the seed crystal and the crystal length of the methacrylic acid crystal finally obtained, the crystal length of the methacrylic acid crystal, the aspect ratio of the methacrylic acid crystal, and the actual methacrylic acid crystal growth rate ratio between the major axis and the minor axis.
[Comparative Example 2]
A methacrylic acid crystal dissolving operation was performed in the same manner as in Example 2 except that the crystal having a long-axis side crystal length of 13000 μm obtained in Comparative Example 1 was used as a seed crystal. From FIG. 6, it was estimated that the ratio of dissolution rate of methacrylic acid crystals between the major axis and the minor axis under this ΔT condition was about 7-8. Table 3 shows the seed crystal, the crystal length of the methacrylic acid crystal finally obtained, the crystal length of the methacrylic acid crystal, the aspect ratio of the methacrylic acid crystal, and the ratio of methacrylic acid crystals dissolved in the actual major and minor axes.
実施例１と比較例１とを比較すると、長軸側結晶長が７０００μｍ以下の種晶を用い、種晶のアスペクト比よりも小さい長軸と短軸のメタクリル酸結晶成長速度比となるΔＴにて結晶成長操作を行った実施例１では、効率的にメタクリル酸結晶アスペクト比が改善されたことがわかる。 When Example 1 and Comparative Example 1 are compared, a seed crystal having a major axis side crystal length of 7000 μm or less is used, and ΔT that is a methacrylic acid crystal growth rate ratio between a major axis and a minor axis smaller than the aspect ratio of the seed crystal is obtained. In Example 1 where the crystal growth operation was performed, it was found that the methacrylic acid crystal aspect ratio was efficiently improved.
また、実施例２と比較例２とを比較すると、長軸側結晶長が７０００μｍ以下の種晶を用いメタクリル酸結晶溶解操作を行った実施例２では、メタクリル酸結晶溶解操作後のメタクリル酸結晶アスペクト比の悪化が抑制されていることがわかる。 Further, when Example 2 is compared with Comparative Example 2, in Example 2 in which methacrylic acid crystal dissolution operation was performed using a seed crystal having a major axis side crystal length of 7000 μm or less, the methacrylic acid crystal after the methacrylic acid crystal dissolution operation It can be seen that the deterioration of the aspect ratio is suppressed.
Claims (5)
A crystal whose major axis side crystal length is 7000 μm or less and whose crystal growth rate ratio defined by the ratio of the major axis side crystal growth rate and the minor axis side crystal growth rate is smaller than the aspect ratio of the seed crystal Methacrylic acid crystals obtained by the growth operation.
A crystal whose major axis side crystal length is 7000 μm or less and whose crystal growth rate ratio defined by the ratio of the major axis side crystal growth rate and the minor axis side crystal growth rate is smaller than the aspect ratio of the seed crystal A method for producing methacrylic acid crystals by a growth operation.
The production of methacrylic acid crystal according to claim 2, wherein ΔT, which is a difference between the solid-liquid equilibrium temperature and the solution temperature, is controlled so that the crystal growth rate ratio is smaller than the aspect ratio of the seed crystal in the process of growing the crystal. Method.
The method for producing a methacrylic acid crystal according to claim 3, wherein the ΔT is controlled to 0.01 to 5.0 ° C.
The method for producing a methacrylic acid crystal according to any one of claims 2 to 4, wherein the crystal growth operation and the crystal dissolution operation are alternately repeated.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2014019314A JP2015145352A (en) | 2014-02-04 | 2014-02-04 | Methacrylate crystal, and method of producing methacrylate crystal |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2014019314A JP2015145352A (en) | 2014-02-04 | 2014-02-04 | Methacrylate crystal, and method of producing methacrylate crystal |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JP2015145352A true JP2015145352A (en) | 2015-08-13 |
Family
ID=53889829
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2014019314A Pending JP2015145352A (en) | 2014-02-04 | 2014-02-04 | Methacrylate crystal, and method of producing methacrylate crystal |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2015145352A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012140471A (en) * | 2012-02-01 | 2012-07-26 | Mitsubishi Rayon Co Ltd | Method of purifying methacrylic acid |
-
2014
- 2014-02-04 JP JP2014019314A patent/JP2015145352A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2012140471A (en) * | 2012-02-01 | 2012-07-26 | Mitsubishi Rayon Co Ltd | Method of purifying methacrylic acid |
Non-Patent Citations (1)
| Title |
|---|
| HINO, TOMOMICHI ET AL.,: "Crystal growth phenomena of methacrylic acid under the presence of maleic acid in melt crystallizati", JOURNAL OF CHEMICAL ENGINEERING OF JAPAN, vol. (2012), 45(10), 868-872, JPN6017043225, 2012 * |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5962817B2 (en) | Crystallization method and crystallizer | |
| JP5929480B2 (en) | Method for purifying methacrylic acid | |
| JP5722771B2 (en) | Crystallization method of (meth) acrylic acid | |
| US10919834B2 (en) | Method for producing (meth)acrylic acid | |
| JP5112898B2 (en) | Crystallization method and system for (meth) acrylic acid | |
| WO2013103112A1 (en) | Method for purifying methacrylic acid | |
| CN102227399A (en) | Method for purifying lactic acid by crystallization | |
| WO2011001887A1 (en) | Device for crystallizing acrylic acid and method for crystallizing acrylic acid using same | |
| JP2015145352A (en) | Methacrylate crystal, and method of producing methacrylate crystal | |
| JP5336794B2 (en) | Purification method of raw material crude crystals | |
| JP6097181B2 (en) | Method for producing (meth) acrylic acid | |
| JP6635176B2 (en) | Method for purifying and producing methacrylic acid | |
| TWI772542B (en) | Method for producing 2,6-naphthalene dicarboxylic acid | |
| JP5569108B2 (en) | (Meth) acrylic acid purification method | |
| TW202104154A (en) | Method for manufacturing binaphthylcarboxylic acid | |
| JP6214156B2 (en) | Method for purifying methacrylic acid | |
| US20240010599A1 (en) | Method for purifying compound | |
| JP2018135275A (en) | Method of purifying methacrylic acid and methacrylic acid crystal | |
| JP2018135276A (en) | Method of purifying methacrylic acid and methacrylic acid crystal | |
| JP5581316B2 (en) | Method for producing (meth) acrylic acid | |
| KR100342148B1 (en) | Method of Purifying Carbazole Ester Precursors of 6-Chloro-α-Methyl-Carbazole-2-Acetic Acid | |
| JP2020132612A (en) | Solid-liquid separation method, and method for purifying (meth) acrylic acid using the same and method for producing purified (meth) acrylic acid | |
| JP5774928B2 (en) | Acrylic acid production method | |
| CN116332754A (en) | Method for purifying trans-2-butenoic acid by melt crystallization | |
| CN117412946A (en) | Process for producing easily polymerizable compound |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20170105 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20171030 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20171114 |
|
| A02 | Decision of refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A02 Effective date: 20180515 |