KR20140128676A - Organic material purification method and its refinery system using Ionic liquids - Google Patents

Abstract

An apparatus for refining a solution based organic material according to the present invention comprises: a double boiling means having a volume to store a fluid for double boiling and a heating function; a storing means which is installed inside the double boiling means, is heated by the fluid for double boiling, and stores an ionic solution, where an organic material for an organic light emitting diode (OLED) is dissolved; a refining means which is installed such that a portion of the refining means is located inside the storing means and recrystallizes and recollects the organic material for an OLED inside the ionic solution on a surface of a rotating member while cooling down the ionic solution, which is heated by the fluid for double boiling, according to a temperature gradient principle; and a control means which controls the double boiling means and the refining means to control a heating temperature of the fluid for double boiling and a cooling temperature of the ionic solution. According to the present invention, the organic material for an OLED, which is dissolved in the ionic solution, is recrystallized by using the temperature gradient principle, thereby the organic material can be simply refined and recollected at low cost. That is, sublimation and vacuum processes of a prior art can be omitted when refining the organic material, thereby simplifying and lowering cost of the refining process.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an organic material purification method,

The present invention relates to a solution-based organic material purification technique, and more particularly, to a solution-based organic material purification technology for purifying an organic material for OLED (Organic Light Emitting Diodes) dissolved in ionic liquids by recrystallization using a temperature gradient principle Based organic material purification apparatus and a method thereof.

In recent years, OLED display devices have attracted attention as next generation display devices. This is because not only the high driving voltage required by the inorganic LED is required, but also the advantage of self-luminescence, thin film, fast response speed, wide viewing angle, and flexibility of various colors due to various organic compounds. Such an OLED refers to a device that generates excitons in which holes and electrons are recombined in the light emitting layer to emit light, and emits light having a specific wavelength by energy from the generated excitons.

1 is a conceptual view showing a structure of an OLED. 1, the OLED includes an anode 120, a hole injection layer (HIL) 130, a hole transport layer (Hole transport) 130, and a hole transport layer (HTL) 140, an emission layer (EML) 150, an electron transport layer (ETL) 160, an electron injection layer (EIL) 170, and a cathode ) 180 are sequentially formed.

Organic materials for light emission and charge transport are required in fabricating an OLED having such a stacked structure. However, since the organic materials directly participate in the recombination of injected holes and electrons as well as the injection of electrons and holes, the purity of the organic materials plays an important role in determining the color, luminous efficiency and lifetime of the OLED. That is, a small amount of impurities in the organic material increases the probability of disappearance of the injected charges, lowering the probability of recombination of holes and electrons, resulting in a decrease in luminous efficiency, as well as a new energy level due to the addition of impurities, .

Therefore, in order to achieve an electroluminescent device with high luminance, high efficiency, and long life, it is necessary to optimize the electroluminescent device structure, develop new materials excellent in hole (or electron) injection and transport properties, It is required to improve the purity of the organic material.

On the other hand, when purifying an organic material for OLED, a recrystallization method using a solvent or a recrystallization method by sublimation is generally used. The recrystallization method by sublimation has a characteristic that the organic material is sublimated and recrystallized under vacuum, so that no impurities are introduced. Therefore, a conventional sublimation purification method is generally used as a method for purifying an organic material for an organic electroluminescence device.

Here, sublimate refers to a gas-solid transition occurring at a temperature and pressure below the triple point in the phase equilibrium. Even if the material is pyrolyzed by heating at normal pressure, it can not be decomposed even at a relatively high temperature under a pressure lower than the triple point. In the sublimation apparatus capable of controlling the temperature gradient by using such a property, the operation of separating the sublimation point from the other sublimation state without heating the mixed substance by heating the mixed substance is called a vacuum sublimation method. Such a vacuum sublimation method is a pure physical method and is useful for the purification of an organic material for an OLED because it does not depend on the use of an auxiliary reagent or other chemical methods and thus has no contamination of a sample and has a large separation rate.

A conventional method for purifying an organic material for OLED, which is currently in use, is a train sublimation purification method. In this method, the material to be refined is placed at the end of a long hollow tube, and the tube is heated with a heater while the inside of the tube is evacuated by using a vacuum pump to make a temperature gradient across the tube. By doing so, the material can be separated using the difference in recrystallization position due to the difference in sublimation point between the material to be separated and the impurity. In some cases, nitrogen or inert gas, which does not react with the material constituting the purification apparatus, is flowed within a range in which the degree of vacuum does not significantly decrease from a high temperature side to a low temperature side, and is used as a carrier gas for transporting an organic material gas. Such transport gas serves to smoothly flow the organic material gas.

2 is a schematic view showing the constitution of the sublimation purification apparatus according to the prior art for performing the continuous sublimation purification method. 2, the refining material is contained in the crucible 240, and the crucible 240 is disposed on one side of the second quartz glass tube 210. On the other hand, the outer side of the second quartz glass tube 210 has a structure in which the first quartz glass tube 220 is wrapped. Here, the crucible 240 is configured to have a pair of lids that are made of stainless steel material and have holes, though not shown, but are fitted to both ends of a hollow cylindrical quartz tube having open ends at both ends.

The heater 250 is installed so as to surround one side of the first quartz glass tube 220. At this time, the heater 250 is installed at a corresponding position where the crucible 240 is located. The vacuum pump 230 is disposed on the other side of the second quartz glass tube 210 to maintain the inside of the second quartz glass tube 210 in a vacuum state.

In the sublimation refining apparatus 200 having the above structure, the interior of the second quartz glass tube 210 is first evacuated by using the vacuum pump 230, and a small amount of the transportation gas is introduced into the second quartz glass tube 210 2 quartz glass tube 210 to form a fine pressure gradient. When the temperature is gradually increased by using the heater 250, a temperature gradient is formed over the entire second quartz glass tube 210, and the temperature distribution formed at this time shows the shape of a normal distribution curve.

On the other hand, when the temperature of the crucible 240 is higher than the sublimation point of the material to be refined contained therein, the material starts to sublimate. After the gas molecules are formed outside the crucible 240, ) Starts to move in the installed direction. At this time, impurities having a lower sublimation point than the material to be refined remain in the crucible 240.

The gas molecules moving in the direction in which the vacuum pump 230 is installed are again transferred to the solid phase in the section of the second quartz glass tube 210 having the temperature lower than the sublimation point, State. Reference numeral 260 denotes a refining material formed in a crystalline state on the inner surface of the second quartz glass tube 210. On the other hand, when the heating time is elapsed, the heating is stopped and the glass is slowly cooled. When the temperature is equal to the room temperature, the second quartz glass tube 210 is disassembled and the refined material 260 in the crystalline state is scraped off and recovered.

However, organic materials used in OLEDs must be in a high-purity state with an extremely low impurity content, and it is difficult to obtain a material having the required purity with a single purification. Therefore, the purification method using the apparatus shown in FIG. 2 requires a repetition of the sublimation purification process several times to obtain a material having high purity, and therefore, it takes a long time for the purification due to the repetition of the purification process, which is unsuitable for mass production.

In addition, since a sublimation purification step of several stages is carried out, it is necessary to obtain a purified amount of less than 70% of the initially introduced organic material, which is expensive and consumes a large amount of electric power.

In other words, the sublimation purification method has an advantage in that the raw material can be refined into an organic material having high purity, but a considerable amount of the organic material is lost together with the inert gas during the process of sublimation- , The yield of the final purified material compared to the starting material is very low. Therefore, the energy consumed in the purification process is large, This ultimately causes a problem that the cost of the organic material increases.

DISCLOSURE OF THE INVENTION Accordingly, the present invention has been made in order to solve the problems of the prior art as described above, and it is an object of the present invention to provide a method and apparatus for recrystallizing an organic material for OLED dissolved in an ionic liquid using a temperature gradient principle, And an object of the present invention is to provide a solution-based organic material refining apparatus and method thereof.

According to an aspect of the present invention, there is provided a solution-based organic material refining apparatus comprising: a tank for storing a fluid for a bath and a heating means having a heating function; And an ionic liquid in which a part of the ionic liquid is dissolved is dissolved in an ionic liquid on the surface of a rotating member that is rotated while cooling the ionic liquid heated by the fluid for hot water, A purifying means for purifying and recovering the organic material for OLED by recrystallization through a temperature gradient principle, and a control means for controlling the heating temperature of the fluid for the bath and the cooling temperature of the ionic liquid by controlling the soaking means and the purifying means .

According to the present invention, the refining means includes: rotation means having the rotation member installed so that a part thereof is positioned in the storage means; and cooling means provided along the inside of the rotation member to cool the rotation member, A cooling means for cooling the ionic liquid in contact therewith, and a temperature sensing means for sensing the temperature of the ionic liquid provided on the rotary member.

According to another aspect of the present invention, there is provided a solution-based organic material purification method using the solution-based organic material purification apparatus configured as described above, The method comprising the steps of: supersaturated organic material for OLED; rotating the rotating member to collect the organic material for OLED dissolved in supersaturated state in the ionic liquid on the rotating member; and cooling the temperature of the rotating member Cooling the surface of the rotating member rotating using the temperature gradient between the ionic liquid in contact with the fluid for bathing and the ionic liquid in contact with the rotating member cooled by the cooling means, And gradually growing and recovering the material.

Further, according to the present invention, the supersaturation step is characterized by proceeding to the point of time when visual recrystallization occurs.

This invention can recrystallize an organic material for OLED dissolved in an ionic liquid by using a temperature gradient principle, and purify and recover it simply and inexpensively. That is, the present invention can simplify the purification process and reduce the cost because the conventional sublimation and vacuum steps can be omitted in purifying the organic material.

1 is a conceptual view showing a structure of an OLED,
FIG. 2 is a schematic view showing a constitutional relationship of a conventional sublimation purification apparatus,
FIG. 3 is a conceptual diagram showing a constitutional relationship of a solution-based organic material refining apparatus according to an embodiment of the present invention,
FIG. 4 is a flowchart illustrating a purification method using the solution-based organic material purification apparatus shown in FIG.

Best Mode for Carrying Out the Invention Hereinafter, preferred embodiments of a solution-based organic material refining apparatus and method according to the present invention will be described in detail with reference to the accompanying drawings.

3 is a conceptual diagram showing a constitutional relationship of a solution-based organic material refining apparatus according to an embodiment of the present invention. 3, the solution-based organic material refining apparatus 300 according to this embodiment includes a bathtub unit having a volume for storing a bathtub fluid and a heating function, A storage means for storing the ionic liquid in which the organic material for OLED is heated and a portion for storing the organic material for OLED in the ionic liquid by cooling the ionic liquid heated by the fluid for the bath, And a control means for controlling the heating temperature of the fluid for hot water and the cooling temperature of the ionic liquid by controlling the refining means for recrystallizing and purifying through the temperature gradient principle and the hot water tank means and the refining means.

The hot water tank includes a first storage tank 310 having a predetermined volume for storing water or oil as a fluid for hot water and a heating member for heating the water or oil stored in the first storage tank 310 to a predetermined temperature Not shown). Here, it is preferable that the first reservoir 310 is made of a material that does not allow the heat of the hot water to be discharged to the outside. The heating member is installed along the inner side and / or the outer side of the first reservoir 310 to heat the fluid for the hot water or to heat the fluid for hot water by being installed on the same side as the bottom surface of the first reservoir 310 . On the other hand, the heating member may be configured to control the temperature depending on the type of the organic material for OLED dissolved in the ionic liquid or to automatically operate when the temperature is lower than the set temperature value. At this time, the heating member is controlled by the control means.

As the ionic liquid according to this embodiment, 1-butyl-3-methylimidazorium bis (trifluoromethylsulfonyl) imide (BMIM (trifluoromethylsulfonyl) imide) TFSI) or 1-octyl-3-methylimidazorium bis (trifluoromethyl sulfonyl) imide (OMIM TFSI) of formula (2) have.

Such an ionic liquid (BMIM TFSI, OMIM TFSI) is a nonvolatile organic solvent which is used to dissolve organic materials and impurities in an ionic liquid, Due to the mechanism that the material first recrystallizes, it can be used to purify and recrystallize various organic materials.

On the other hand, BMIM TFSI and OMIM TFSI are low melting point, low vapor pressure, nonflammable, consist of organic molecular ions, control of combination ratio between negative and positive ions And properties (controllable properties by combinations of anions and cations).

The ionic liquid according to this embodiment is used for purifying and recrystallizing an organic material and is stable as a liquid phase even at 170 ° C and 10 ^-7 Torr and can be used as a solvent in a vacuum process.

As organic materials for OLEDs according to this embodiment, Alq3 (Tris (8-hydroxyquinolinato) aluminum) material as an electron transport layer (ETL) material and NPB (N, N'-bis naphthalen-1-yl) -N, N'-bis (phenyl) -benzidine. Here, Alq3 has a melting point of 419.9 占 폚 and NPB has a melting point of 283.6 占 폚. However, since the present invention dissolves a solvent by using it as an ionic liquid, it can dissolve the organic material raw material within about 200 ° C.

On the other hand, there are a variety of deposition materials (organic materials) used for fabricating OLED devices other than the above two materials. Therefore, the present invention may use these various kinds of organic materials.

The storage means includes a second storage tank 320 installed in the first storage tank 310 to store the ionic liquid in which the organic material for OLED is dissolved. On the other hand, since the second reservoir 320 needs to heat the ionic liquid by using the heat of the hot water, it is preferable that the second reservoir 320 is made of a material having excellent thermal conductivity. In addition, the second reservoir 320 is configured to have a smaller size than the first reservoir 310, and is configured to have a sufficient space between the first reservoir 310 and the bathtub. The bottom surface of the second reservoir 320 may be mounted on the bottom surface of the first reservoir 310 or may be connected to the bottom surface of the first reservoir 310 using a supporting member, It can be installed at a fixed distance.

The purifying means is a purifying means for purifying an organic material for an OLED in an ionic liquid through a temperature gradient principle, the purifying means comprising a rotating means installed in a part of the inside of the second storing means 320, Cooling means for cooling the means for cooling the ionic liquid in contact with the rotating means, and temperature sensing means for sensing the temperature of the ionic liquid provided on the rotating means.

The rotating means has a rotating member 330, which is installed so as to be partially positioned in the second storage tank 320, and a driving motor (not shown), which provides rotational driving force to the rotating member 330. Here, the rotary member 330 is installed along the inner center of the second storage tank 320, but spaced apart from the bottom surface of the second storage tank 320.

The cooling means cools the ionic liquid in contact with the rotary member 330 while cooling the rotary member 330 and includes a cooling member 340 installed along the inside of the rotary member 330, (Not shown) for providing a power for cooling the heaters 340 and 340, and the like. Here, the cooling member 340 is installed along the inside of the rotating member 330 in the form of a cooling pipe or a cooling coil.

The temperature sensing means senses the temperature of the ionic liquid and is constituted by a temperature sensing member 350 installed at an end of the rotating member 330. At this time, the temperature information sensed by the temperature sensing member 350 is supplied to the control means and utilized.

The rotating means and the cooling means constituted as described above are controlled by the control means. That is, the rotational speed of the driving motor for driving the rotating member 330, the cooling temperature of the driving member for cooling the cooling member 340, and the like are controlled by the control means.

Hereinafter, a method of purifying an organic material using the solution-based organic material refining apparatus of this embodiment will be described.

FIG. 4 is a flowchart illustrating a purification method using the solution-based organic material purification apparatus shown in FIG. As shown in FIGS. 3 and 4, the solution-based organic material refining method according to this embodiment refines the organic material for an OLED in an ionic liquid by recrystallizing it. The surrounding temperature surrounding the ionic liquid is increased from room temperature to 200 ° C to supersatethe organic material for OLED in the ionic liquid (S410). Such a process time is firstly progressed to the point where visual recrystallization occurs, but the process time may be about 30 to 120 minutes.

Then, the rotating member 330 is rotated to collect the organic material for OLED dissolved in supersaturated state in the ionic liquid in the rotating member 330, and the temperature of the ionic liquid is cooled through the cooling member 340 (Rapid cooling) (S420). At this time, the quenching temperature range may be set to a process temperature of -20 ° C. This quenching process causes a temperature gradient in the ionic liquid. That is, a temperature gradient phenomenon occurs between the ionic liquid in contact with the bathing fluid in the first reservoir 310 and the ionic liquid in contact with the rotating member 330 cooled by the cooling member 340. The temperature gradient causes the recrystallized organic material to adhere to the surface of the rotatable member 330, which gradually rotates. Through this process, the purified organic OLED material can be recovered (S430).

In the purification by the above-described method, the components may be controlled through the control means in accordance with the process conditions as described above. That is, the control conditions of the control means are designed under optimum conditions in consideration of the viscosity of the OLED organic material as the process variable, the temperature of the fluid for hot water, the quenching temperature of the cooling member 340, , Organic materials for various OLEDs can be purified by recrystallization.

In the foregoing, the solution-based organic material purification apparatus of the present invention and the description of the method have been described with reference to the accompanying drawings, which illustrate the best preferred embodiment of the present invention. It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention as defined by the appended claims. Examples or modifications will also fall within the scope of the claims of this invention.

300: organic material refining apparatus 310: first storage tank
320: second reservoir 330: rotating member
340: cooling member 350: temperature sensing member

Claims (6)

A hot water tank having a volume for storing a hot water bath and a heating function,
Storage means for storing an ionic liquid which is installed in the water tank and is heated by the fluid for hot water and in which the organic material for OLED is dissolved,
An organic material for OLED in the ionic liquid is recrystallized and purified through the temperature gradient principle on the surface of the rotating member which is installed to be partially positioned in the storage means and rotates while cooling the ionic liquid heated by the liquid for hot water, ≪ / RTI >
And a control means for controlling the heating means and the refining means to control the heating temperature of the fluid for hot water and the cooling temperature of the ionic liquid. The method according to claim 1,
Wherein the ionic liquid is one of BMIM TFSI (1-Butyl-3-methylimidazorium bis (trifluoromethyl sulfonyl) imide) or OMIM TFSI (1-Octyl-3-methylimidazorium bis Refining device. The method according to claim 1,
The organic material for OLED is characterized by being a material of Alq3 (Tris (8-hydroxyquinolinato) aluminum) or NPB (N, N'-bis (naphthalen-1-yl) -N, N'-bis Based organic material refining apparatus. The method according to claim 1,
Wherein the purifying means comprises: rotation means having the rotation member installed in a part of the storage means; cooling means for cooling the rotation member installed along the inside of the rotation member to cool the ionic liquid in contact with the rotation member; And a temperature sensing means provided on the rotating member for sensing the temperature of the ionic liquid. A purification method using the solution-based organic material purification apparatus according to claim 1,
Supersaturated organic material for an OLED in an ionic liquid using a bathing method using a fluid for bathing,
Rotating the rotating member to collect the organic material for OLED dissolved in supersaturated state in the ionic liquid on the rotating member, and cooling the temperature of the rotating member through the cooling means; and
The recrystallized organic material is gradually grown on the surface of the rotating member rotating using the temperature gradient between the ionic liquid in contact with the fluid for hot water and the ionic liquid in contact with the rotating member cooled by the cooling means And recovering the organic-based organic material. The method of claim 5,
Wherein the supersaturation step proceeds to the point of time when visual recrystallization occurs.

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