TW201601813A - Novel method for purifying organic solid materials - Google Patents

Abstract

A novel method for purifying organic solid materials, including the procedures of distilling raw material, collecting impurities and purified products, which are carried out under vacuum or low pressure state, wherein the distillation procedure is stepwise heating, putting the raw material into a distillation vessel, the distillation vessel and a purified product collection container were heated to T1, and maintaining the temperature at T1, then collected by an impurity collecting container; and afterwards the distillation vessel was heated to T2, all purified material was distilled off and collected by the purified product collection container. Advantages of the present invention comprise a lower equipment cost, rapid purification rate, the higher the efficiency of production, less energy consumption as well as smaller dust hazards.

Description

New purification method for organic solid materials

The invention relates to a method and a device for purifying a chemical substance, in particular to a novel purification method of an organic solid (photoelectric) material, in particular to a method for purifying an organic solid (photoelectric) material in which a liquid phase exists in a vacuum heating state.

In recent years, with the development of organic photoelectric materials, higher requirements have been put forward for large-scale purification equipment and methods for solid organic materials. Commonly used solid organic material purification methods include recrystallization, chromatography, solvent washing, etc., but these methods are not suitable for the purification requirements of organic photoelectric materials, because the materials obtained by these chemical purification methods are difficult to achieve more than 99.5%. High purity, and the solvent remaining in the material adversely affects the vacuum process of organic optoelectronic devices. Therefore, material manufacturers at home and abroad generally use sublimation methods to purify materials to meet the high purity requirements of materials in the organic electronics industry.

However, due to the difference in physical properties of solid materials, there are also differences in the physical processes experienced by solid organic materials in the purification process using sublimation instruments, which can be roughly divided into two categories: the first category is the transformation process of “solid-gas-solid”; The second category is the transformation process of “solid-liquid-gas-solid (liquid)”. The first type of material is not sublimed directly through the liquid state, such as the commonly used electron transport material AlQ ₃ . The second type of material is also widely existed. For example, the purification process of the material of the triarylamine in the sublimation instrument belongs to the second type of transformation process, and the gasification temperature Te of the material is higher than the melting point Tm. There are some problems with the purification of such substances by sublimation: on the one hand, the vaporized material will condense in the region between the temperature between Te and Tm, and will exist in liquid form, which will easily cause the liquid to flow to other areas and be contaminated. On the other hand, the glass transition temperature of such materials is usually greater than room temperature, so the liquid will agglomerate after condensation, which causes difficulties in product collection, grinding and dispensing.

Since such Tm<Te type solids are converted to a liquid state after heating, it is considered to use distillation to purify such substances. However, the conventional distillation purification method is directed to substances that are liquid at normal temperature and pressure, such as alcohol, oil, seawater, and the like. Such materials only need to heat the liquid at a lower temperature and under reduced pressure, and the pure components of different components are distilled in order from the lowest to the highest boiling point, and are separately collected by condensation to achieve a purification effect. Industrial distillation equipment for these liquid materials has matured, but such liquid-oriented distillation apparatus and processes are not suitable for the purification of solid organic materials. There are also distillation equipment for solid materials in the industry, such as lithium, zinc distillation equipment, and molecular distillation equipment, but because these equipments are complex in structure, bulky, and costly, they do not have good purification of organic solid (photovoltaic) materials. Economic.

In view of the above-mentioned problem of purifying an organic photoelectric material having a gasification temperature (Te) close to or greater than a melting point (Tm) thereof in a vacuum heating state, the present invention provides a novel method for purifying an organic solid, which can separately collect impurities and products. Using this method, the purity of the product can reach 99.5% or higher, and the method has lower equipment cost, faster purification speed, higher yield, less energy consumption and more dust damage than the sublimation method generally adopted in the industry. Small and can increase the amount of material added in the vapor deposition crucible.

A novel purification method of an organic solid material, comprising a distillation and impurity and product collection step of a substance to be purified under vacuum or a low pressure state, characterized in that the distillation step is heated in a stepwise manner, the step heating method is: firstly, the substance to be purified Adding to the distillation vessel, heating the distillation vessel and the product collection vessel to T1, keeping T1, removing the impurities with low boiling point or low sublimation temperature, collecting by the impurity collecting container; then continuing to heat the distillation vessel to T2 to boil the material to be purified, and keeping warm T2, distilling out all products, collected by the product collection container; the T1 is greater than or equal to the liquid-vapor transition temperature of the low boiling point or low sublimation temperature impurities, and T1 is higher than the melting point temperature Tm of the product, and the T2 is greater than or equal to the product liquid a gas transition temperature, and T2 is smaller than a decomposition temperature Td of the product, wherein the distillation vessel, the product collection vessel, and the impurity collection vessel are in communication with each other, and the organic solid material is any organic solid which must be first converted into a liquid state when sublimated under vacuum. material.

Before the distillation step, a melting step of the substance to be purified is carried out, wherein the substance to be purified is heated and melted in a solid liquefier, and the solid liquefier is connected to the distillation vessel through a switchable high temperature valve.

A protective gas is also introduced into the solid liquefier.

The shielding gas is nitrogen or argon.

The T1 is higher than the volatilization temperature of the low boiling or low sublimation temperature impurities and is lower than the boiling point Tb of the product.

The T2 is greater than the boiling point Tb of the product.

The temperature within the solid liquefier is greater than the melting point of the product.

The low pressure is <10 Pa.

After the whole product was distilled off, the heating of the distillation vessel and the product collection vessel was stopped, and after cooling to below 50 ° C, the vacuum was taken out to remove the product.

The purification method of the present invention is a purification method for an organic photoelectric material having a vaporization temperature (Te) close to or greater than its melting point (Tm) and a boiling point (Tb) smaller than a decomposition temperature (Td) in a vacuum heating state. The raw material is heated to liquefy in a distillation vessel, and then the low boiling point (or low sublimation temperature) impurities and the higher boiling point product are successively distilled in a stepwise manner; the product collection container is heated and maintained at a certain temperature, which is high At the boiling point (or sublimation temperature) of the impurity but below the boiling point of the product, the product condenses and the impurities are driven away to the impurity collection container; the impurity collection container is at a sufficiently low temperature where the impurities condense; the vacuum system is connected to the impurity collection The end of the vessel provides a high vacuum to the distillation vessel, product collection vessel and impurity collection vessel, reducing the boiling point (sublimation temperature) of the product and impurities.

The purification process has batch continuity to facilitate large-scale production; the solid is melted and maintained in a liquid state in the solid liquefier, the high temperature valve is opened, and the liquid material is sucked into the distiller due to the pressure difference between the solid liquefier and the distiller In the distillation, the product is heated and distilled, and the distilled product is condensed and collected in the product collector, and the impurities obtained by distillation (sublimation) are condensed and accumulated in the impurity collector; after the raw materials in the distiller are purified, they can be immediately removed from the solid liquefier. A new batch of raw materials is added to the distiller to continue distillation, ensuring the demand for large-scale continuous production.

The shielding gas may be nitrogen, argon, or other gas inert to the purification material to protect the product from oxidation during heating.

After most of the material in the distillation vessel is distilled off, the heating is stopped, and after the system is cooled to below 50 ° C, the vacuum is taken out and the sample is taken out.

Working principle: At present, most organic photoelectric materials are small molecular compounds with a certain degree of conjugation. Industrial synthesis of such conjugated small molecules generally uses metal catalyzed reactions, and impurities in the products are mainly introduced or retained in the synthesis process. According to the analysis of the instrument, impurities are mainly divided into two categories: one is a metal catalyst, which is difficult to sublimate or distill, and is the main residue of the high-temperature purification process; the other is that the catalytic reaction is incomplete and the residual molecular weight is small. The product, which is smaller in molecular weight than the product, is more easily distilled or sublimed. For the above two types of impurities, the second type of impurities are first distilled (sublimed) at a temperature higher than the boiling point of the product, and allowed to condense in the impurity collecting container. After the second type of impurities have been removed, the temperature of the distillation vessel is raised to the boiling point of the product, and the product is distilled off and condensed in the product collection vessel. The first type of impurities cannot be distilled and remain in the distillation vessel.

Example 1 100 g of an organic light-emitting diode (OLED) hole transport material (NPB) crude product was purified by the method of the present invention. NPB is a solid at room temperature, its melting point is about 280 ° C, and the purity of the crude product is 97.5%. It needs to be purified to a purity of 99.5% or more.

The specific operation method is as follows. (1) 100 g of crude NPB was added to a distillation vessel, and then the distillation vessel was sealed. (2) The vacuum pump is turned on, and the distillation container, the product collection container, and the impurity collection container are evacuated to a vacuum of less than 10 Pa. (3) Turn on the heating temperature control system, set the temperature of the distillation vessel to 350 ° C, and set the temperature of the product collection container at 320 ° C (the actual temperature of the liquid will be somewhat less than the set temperature of the container). (4) The crude liquid NPB in the distillation vessel was kept at 350 ° C for 10 minutes to remove most of the low boiling point (or low sublimation temperature) impurities. (5) The temperature of the distillation vessel is gradually raised to 450 ° C to boil the NPB liquid in the distillation vessel, and the distillation head is sufficiently heated and kept to allow the NPB vapor to enter the product collection vessel. (6) Continuous heating, the distillation vessel was kept at 450 ° C until most of the NPB was distilled, and then the heating was cooled to 50 ° C or less, and the vacuum was taken out to remove the pale yellow NPB solid in the product collection container.

The entire distillation process lasted about 3 hours. The cost of the whole distillation system was about 35,000 RMB, and the power consumption was about 5 degrees. 82 g of NPB block pure product was obtained, and the purity was 99.7% by HPLC.

Comparative Example: In order to verify the advantages of the distillation apparatus and the purification method of the present invention, the same batch of 100 g NPB was subjected to sublimation purification using a model sublimation instrument (cost of about 500,000 RMB). The sublimation of 100g NPB takes 18 hours and consumes about 30 degrees of electricity. Finally, 75g of pure powder with a purity of 99.7% is obtained.

Example 2 A crude product of 300 g of OLED hole transport material NPB was purified by continuous distillation using the method of the present invention. NPB is a solid at room temperature, its melting point is about 280 ° C, and the purity of the crude product is 97.5%. It needs to be purified to a purity of 99.5% or more.

The specific operation method is as follows. (1) 250 g, 50 g of crude NPB were added to the solid liquefier and the distiller, respectively, and the high temperature valve was closed at this time. (2) The solid liquefier is evacuated and flushed with nitrogen, and the operation is repeated three times to ensure that the NPB in the solid liquefier is sufficiently protected against oxidation upon heating. (3) Turn on the vacuum pump and evacuate the distiller, product collector, and impurity collector to less than 50 mtorr. (4) Turn on the heating temperature control system, set the solid liquefier temperature to 320 ° C, the distiller temperature to 350 ° C, and the product collector temperature to 320 ° C (note that the actual temperature of the heated liquid is Will be somewhat less than the set temperature). (5) The crude liquid NPB in the distiller was kept at 350 ° C for 10 minutes to remove low boiling point (or low sublimation temperature) impurities. (6) The retort temperature is gradually increased to 450 ° C to boil the NPB liquid in the distiller, and the distillation head is sufficiently heated and kept to allow the NPB vapor to enter the product collector. (7) Continuous heating, the distiller was kept at 450 ° C until most of the NPB was distilled. (8) Open the high temperature valve, the crude liquid NPB in the solid liquefier is sucked into the distiller under the pressure difference at one end of the shielding gas and the other end is vacuum. When the NPB in the solid liquefier is reduced by about 1/5, Close the high temperature valve. (9) The above operations of the fifth to eighth steps were repeated to carry out continuous distillation of NPB.

The entire distillation process lasted about 4 hours. The cost of the whole distillation system was about 50,000 RMB, and the power consumption was about 6 degrees. 250 g of NPB pure product was obtained, and the purity was 99.7% by HPLC.

Comparative Example: In order to verify the advantages of the distillation apparatus and the purification method of the present invention, the same batch of 300 g NPB was subjected to sublimation purification using a submersible instrument of a certain type (cost of about 500,000 RMB). The sublimation of 300g NPB took 24 hours and consumed about 40 degrees. Finally, 240g of pure 99.7% purity was obtained.

Compared with the pure NPB obtained by different purification methods, the pure product obtained by distillation method is blocky, which is very convenient to obtain and transfer; and the pure NPB obtained by sublimation is powder, and the product is scraped and transferred. A large amount of dust floats or adheres, which is not conducive to product handling and personnel health.

Through comprehensive comparison, the distillation apparatus and the purification method of the present invention have lower equipment cost, faster purification speed, higher yield, less energy consumption, and dust than the sublimation equipment and method commonly used for purifying solids in the electronics industry. A less harmful advantage.

[Fig. 1] is a process flow diagram of the present invention.

Claims (9)

A novel purification method of an organic solid material, comprising a distillation and impurity and product collection step of a substance to be purified under vacuum or a low pressure state, characterized in that the distillation step is heated in a stepwise manner: the step heating method is: first to be purified The substance is added to the distillation vessel, and the distillation vessel and the product collection vessel are heated and heated to T1, and the T1 is kept, and the low boiling point or low sublimation temperature impurities are removed, and collected by the impurity collecting container; then the distillation vessel is further heated to T2 to boil the substance to be purified. Insulating T2, distilling out all products, collected by the product collection container; the T1 is greater than or equal to the liquid-vapor transition temperature of the low boiling point or low sublimation temperature impurities, and T1 is higher than the melting point temperature Tm of the product, and T2 is greater than or equal to the product. a liquid-gas transition temperature, and T2 is smaller than a decomposition temperature Td of the product, wherein the distillation vessel, the product collection container, and the impurity collection container are in communication with each other, and the organic solid material is organically converted into a liquid state when sublimated under vacuum. Solid material. The method of claim 1, wherein the step of distilling is preceded by a melting step of the substance to be purified, wherein the substance to be purified is heated and melted in a solid liquefier, and the solid liquefier is passed The high temperature valve of the switch is in communication with the distillation vessel. The method of claim 2, wherein the solid liquefier is further provided with a shielding gas. The method of claim 3, wherein the shielding gas is nitrogen or argon. The method of claim 1, wherein the T1 is higher than a volatilization temperature of a low boiling or low sublimation temperature impurity and is lower than a boiling point Tb of the product. The method of claim 1, wherein the T2 is greater than the boiling point Tb of the product. The method of claim 2, wherein the temperature in the solid liquefier is greater than the melting point of the product. The method of claim 1, wherein the low pressure is <10 Pa. The method of claim 1, wherein after the whole product is distilled off, the heating of the distillation vessel and the product collection vessel is stopped, and after cooling to below 50 ° C, the vacuum is taken out to remove the product.