TW200930796A - Method of producing liquid crystal composition - Google Patents

Abstract

The object of the present invention is to provide an efficient method for producing a liquid crystal composition having high reliability during the production of a liquid crystal composition by mixing more than two kinds of liquid crystal compounds. The method of attaining the said object is characterized in that at least one of the more than two kinds of liquid compounds having a melting point higher than 30 DEG C is irradiated by a microwave. The said method of this invention is capable of producing a liquid crystal composition having high reliability of high quality without using large scale apparatus such as a reducing pressure device, a heating device and the like, and thus is a highly practical method for producing a liquid crystal composition having high reliability.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for producing a liquid crystal composition which can be used as a constituent of a liquid crystal display element. [Prior Art] * Liquid crystal display elements have evolved into various measuring instruments, automotive panels, word processors, electronic PDAs, printers, computers, and televisions, including timers and electronic desktop computers. Wait. The representative of the liquid crystal display system includes: TN (twisted nematic) type, STN (super twisted nematic) type, DS (dynamic light scattering) type, GH (guest master) type or FLC capable of high speed response. Electrical liquid crystal) and the like. In addition, the driving method has evolved from the previous static driving to the multiplex driving, and the simple matrix method has been adopted. Recently, the active matrix method has been put into practical application. The liquid crystal composition used herein is usually produced by mixing two or more kinds of compounds, and the mixing ratio thereof is based on the physical properties of the liquid crystal composition (nematic phase temperature range, refractive index anisotropy (Δη), and dielectric constant). Directionality (Δε ® ), viscosity, elastic constant, etc.) or photoelectric properties (response time, threshold voltage)

The display mode or driving method of the liquid crystal element for the purpose of the purpose of the VT (voltage-temperature curve steepness, etc.) is determined by various numbers, but it is almost necessary for the composition to have heat, light, moisture, etc. High reliability. Further, especially in the case of the active matrix driving method, it is important that the voltage holding ratio (VHR) must be sufficiently high. In order to improve the reliability, resistivity, and voltage holding ratio (VHR) of the liquid crystal composition, it is necessary to achieve high reliability and voltage holding ratio with respect to each liquid crystal compound constituting the composition (VHR 200930796). However, even when a liquid crystal compound having high reliability, resistivity, and voltage holding ratio (VHR) is used, when the liquid crystal composition of these mixtures is produced, there is a possibility that the quality is deteriorated. In the method of producing a liquid crystal composition, there has been proposed a method of removing an organic solvent by mixing after dissolving and mixing by heating or dissolving a liquid crystal compound in an organic solvent (see Patent Document 1). However, the methods disclosed in these proposals are likely to cause quality degradation. For example, in the case of dissolving and mixing by heating, the liquid crystal compound is oxidatively decomposed due to oxygen upon heating, and the resistivity or voltage holding ratio (VHR) of the liquid crystal composition is remarkably lowered. Further, there is a possibility that the liquid crystal upper limit transfer temperature is lowered to cause a change in physical properties or photoelectric characteristics of the liquid crystal composition. Further, in the method of dissolving in an organic solvent, there is a possibility that the resistivity or voltage holding ratio (VHR) of the liquid crystal composition is remarkably lowered due to impurities or dopants of the organic solvent. Further, the organic solvent is not completely removed and remains, and as a result, the resistivity of the liquid crystal composition is lowered or the voltage holding ratio is remarkably lowered. On the other hand, there has also been proposed a method of heating by a lower temperature at a reduced pressure, which is directed to the manufacture of a liquid crystal composition having a low resistance ( (refer to Patent Document 2). . However, the method disclosed in the cited document, although it can be manufactured at a lower temperature, still requires heating, so that the adverse effects caused by heating cannot be completely eliminated, and equipment accompanying heating is also required. Moreover, the method disclosed in the cited document has a problem of a large-scale device that requires decompression. That is, in order to dissolve the liquid crystal compound while decompressing one side, a container capable of withstanding decompression is required, so that the manufacturing apparatus must use a large-scale decompression. Further, although the decompression is 200930796', the vacuum pump is generally used. However, as an accessory device, a well for preventing backflow of the oil mist and a cooling device for cooling the trap are also required. As described above, the method of producing a liquid crystal composition under reduced pressure inevitably leads to an increase in size of the apparatus, which necessitates the investment of excessive capital to correspond to the demand for the liquid crystal composition being increased. In view of the above, it is currently desired to develop a method for efficiently producing a higher quality liquid crystal composition with a simple apparatus. (Patent Document 1) Japanese Laid-Open Patent Publication No. Hei No. 5-105876 (the right column of the fifth page) (Invention Patent Document 2) Japanese Patent Laid-Open Publication No. 2002-1 94356 (page 4) EMBODIMENT OF THE INVENTION [Technical Problem to be Solved] The technical problem to be solved by the present invention is to provide a highly reliable manufacturing process for producing a liquid crystal composition composed of two or more liquid crystal compounds. A liquid crystal composition and a method that can be efficiently produced. [Technical method for solving the problem] The inventors of the present invention have finally achieved the present invention in order to solve the technical problem as described above and to concentrate on the results. The present invention provides a process for producing a liquid crystal composition, which is characterized in that microwaves are irradiated to at least one of liquid crystal compounds having a melting point higher than 30 ° C. [Effect of the Invention] The production method of the present invention can produce a high-quality liquid crystal composition having high reliability without requiring a large-scale apparatus such as a decompression device or a heating device. In the case of 200930796, it is very practical to manufacture a liquid crystal composition which is required to suppress a decrease in resistivity, a small amount of impurities, and a small change in physical properties, and which has high reliability. [Embodiment] [Best Embodiment of the Invention] Hereinafter, an example of the invention will be described. The method of the present invention is to efficiently produce a liquid crystal composition by irradiating microwaves with at least one liquid crystal compound containing at least one liquid crystal compound having a melting point of higher than 30 ° C without using an organic solvent or the like. Object. In particular, it is effective to use two liquid crystal compositions in which two or more kinds of liquid crystal compounds having a melting point of higher than 30 ° C are used, and two or more kinds of melting points of more than 30 ° C are used. The liquid crystal composition of the liquid crystal compound is more effective in the production. The content of the compound having a melting point of 30 ° C or more is preferably 60% or more, more preferably 70% or more, and particularly preferably 80% or more. The liquid crystal composition may contain additives other than the liquid crystal compound. Additives © Antioxidants, UV absorbers, antistatic agents, surfactants, etc. can be used. Further, an optically active compound having liquid crystallinity or non-liquid crystallinity may also be contained. If the amount of the compound having no liquid crystal skeleton is too large, the effect on the characteristics of the liquid crystal will be adversely affected. Therefore, when a compound having no liquid crystal skeleton is to be added, the total content is preferably 5% or less. More preferably, it is 3% or less, and particularly preferably 1% or less. The irradiation time of the microwave is preferably 1 hour or less, more preferably 30 minutes or less. If the temperature when the microwave is irradiated is too high, the quality of the composition to be manufactured 200930796 will be lowered, and if it is too low, it will take time to manufacture, so of course, it has an optimum temperature. Therefore, it is preferably in the range of from 50 ° C to the liquid crystal phase upper limit temperature of the liquid crystal composition obtained by +50 ° C, more preferably in the range of +30 ° C. The frequency of the microwave used is preferably 300 MHz or more, 3 THz or less, and more preferably 500 MHz or more. The irradiation intensity is preferably 100 W or more, more preferably 1 kw or more. According to the process of the present invention, since a liquid crystal composition can be produced at a low temperature, a high-quality liquid crystal composition can be produced in a general atmosphere atmosphere. However, in order to produce a higher quality liquid crystal composition, it is preferred to carry out the irradiation of the microwave under a closed condition, and more preferably in an inert gas atmosphere. The inert gas system is suitable for use with helium, neon, xenon, and the like. Rare gases and nitrogen. Although the production method of the present invention does not require the use of a pressure reducing measure, the production of the composition can be carried out under reduced pressure. The liquid crystal composition obtained by the production method of the present invention is not particularly limited. However, when it is produced under reduced pressure, it is particularly preferable to produce a liquid crystal composition containing a large amount of a liquid crystal compound having a small molecular weight which is volatilized. The molecular weight of the liquid crystal compound is preferably a compound having 300 or less, more preferably a compound having 250 or less. In order to produce the liquid crystal composition more efficiently, it is preferred that the liquid crystal molecules formed are polarized and shifted. Specifically, it can be produced more efficiently than when the liquid crystal compound to be formed has a specific structure or functional group. A preferred structure has at least one aromatic ring in the molecule of the liquid crystal compound. Further, a preferred functional group is an electron-attracting functional group 200930796 of a halogen, a cyano group or the like, and preferably a compound having such a functional group in a molecule, and more preferably has an electron attracting function in the aromatic ring. Base compound. Specifically, the compound to be constituted is preferably a compound represented by the formula (I). R1—A—Z1—B—(z2—C^R2 (I) (wherein R1 and R2 each independently represent an alkyl group having 1 to 16 carbon atoms and having a carbon number substituted by fluorine, An alkoxy group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, an alkenyloxy group having 3 to 16 carbon atoms, a fluorine atom, a chlorine atom or a cyano group; A, B and C systems Each independently represents 1,4-phenylene, 2 or 3-fluoro-1,4-phenylene, 2,3-difluoro-1,4-phenylene, 3,5-difluoro-1, 4-phenylene, 2 or 3-chloro-1,4-phenylene, 2,3-dichloro-1,4-phenylene, 3,5-dichloro-1,4-phenylene, 2-methyl-1,4-phenylene, 3-methyl-1,4-phenylene, naphthalene-2,6-diyl'phenanthrene-2,7-diyl, ef-2,7- Dibasic, trans-1,4-cyclohexylene, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, decahydronaphthalene-2,6-diyl, trans-1,3 -dioxane®-2,5-diyl, pyridine-2,5-diyl, pyrimidine-2,5-diyl, pyridene-2,5-diyl, or 嗒哄-2,5-di And the bases of these may be further substituted with 丨 to 3 fluorine atoms; m represents 0, 1 or 2; Z1 and Z2 each independently represent a single bond, -CH2CH2-, -(CH2 ) 4-, ·0(:Η2...-CH20- -COO-, -CH = CH_, -CF = CF-, _CH = NN = CH_ or -C=C-. However, if m; ^ 2 when 'the two Z2 and C are independently The same or different.) In the formula (I), at least one of A, B and C is preferably an aromatic ring, more preferably 1,4-phenylene, 2 or 3-fluoro-1,4-stretch Phenyl, 2,3-difluoro-l,4-benzobenzene-10-200930796, 3,5-difluoro-1,4-phenylene, 2 or 3·chlorophenyl, 2,3_ Dichloro-hydrazine, 4_phenylene, 3,5-dichloro-1,4-phenylene, 2-methyl-oxime, 4-phenylene, 3-methyl-oxime, 4·phenylene , naphthalene-2,6-diyl, phenanthrene-2,7-diyl, 莽_2,7-diyl, 1,2,3,4-tetrahydronaphthalene-2,6-diyl, pyridine_2, 5-diyl, pyrimidine_2,5-diyl'-pyridyl-2,5-diyl, or oxime-2,5-diyl; especially good, 4_phenyl, 2 or fluoro -^-Extended phenyl, 2,3-difluoro-1,4-phenylene, 3,5-difluoro-barium phenyl. R1 and R2 are preferably one representing a fluorine atom or a chlorine atom. Or a cyano group, and the other one represents an alkyl group having 1 to 16 carbon atoms, an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, and 3 carbon atoms. Combination of alkenyloxy groups up to 16 When the liquid crystal composition for TFT is produced by the method of the present invention, 'R1 and R2 in the compound represented by the formula 较佳 are preferably each independently represent a fluorine atom and an alkyl group having 1 to 16 carbon atoms. a compound having a base or an alkenyl group having 2 to 16 carbon atoms. In this case, the obtained liquid crystal composition has a high voltage holding ratio. <<Examples>> In the following, the present invention will be described in more detail by way of examples, but the present invention is not limited by the examples. In addition, "%" in the compositions of the examples and comparative examples below "It means "% by weight". The microwave irradiation was carried out using a microwave irradiation device (special order product) manufactured by Fuji Electronic Industrial Co., Ltd. (high-frequency output power: 6 kW, oscillation frequency: 2,450 MHz ± 50 MHz). The analysis of the obtained liquid crystal composition used the following apparatus: Gas chromatography: HP6890 -11 - 200930796 manufactured by HEWLETT PACKARD Co., Ltd. The reliability was confirmed by performing the measurement of the resistivity of the liquid crystal composition, using the vapor phase layer. The analysis method confirms the formation of impurities and the decomposition of the mixed compound, and measures the voltage holding ratio, current 値, and physical properties. [Example 1] Production of liquid crystal composition A liquid crystal composition (STN 1 and liquid crystal upper limit temperature: 95.1 ° C) composed of the following compounds was produced.

-12- 200930796 C2H5

F Fl〇^^-c F F c Park·

Coc C^Hg-

Coc

0C2H5

〇4Η9

, 0^0^〇~ 8g 79〇C 5g 71 °C 16g 8°C 2g 31 °C 16g 64°C 2g 80°C 3g 38°C 20g 109°C 9g 177°C 6g 207°C 5g 203° C 4g 210oC or more 4g 210oC or more In a 150 ml-volume separation flask, the respective compounds as described above and the amounts thereof are recited. The separable flask was mounted on a microwave generating device and irradiated with microwave heating at an output of 1 kW. After the irradiation for 10 minutes, the microwave irradiation was stopped, and the separation flask was cooled, and then taken out from the microwave irradiation device -13 - 200930796', whereby 100 g of the nematic liquid crystal state of STN1 was obtained. The resistivity of the obtained liquid crystal composition was measured and found to be 1 · 1×10 11 Ω cm. Further, the obtained liquid crystal composition was analyzed by gas chromatography, and the results were not mixed with the formation of a substance other than the mixed compound, and decomposition of the mixed compound was not observed. The physical properties of the obtained liquid crystal composition were measured, and as a result, the desired properties were obtained. The liquid crystal was injected into the STN panel and the photoelectric characteristics were measured, and as a result, the desired characteristics were obtained. From the results as described above, it is understood that the liquid crystal composition of Example 1 has a very high reliability. The process of the present invention enables the production of high quality liquid crystal compositions in 40 minutes without the need for large scale equipment. [Comparative Example 1] Production of a liquid crystal composition under reduced pressure A liquid crystal composition (STN1) similar to that of Example 1 was produced by the method disclosed in Japanese Laid-Open Patent Publication No. 2002-194356. Weigh the desired amount of liquid crystal compound in an eggplant type flask. Then, the eggplant type flask was mounted on a rotary evaporator. The eggplant flask was immersed in a 50 Φ °C oil bath and rotated. The rotary evaporator was slowly depressurized to 20 kPa using a vacuum pump for 5 minutes. Set the temperature of the oil bath to UOt and raise the temperature at a rate of 5 t /min. After the liquid crystal was changed to a liquid state and was transparent for 30 minutes, the oil bath was changed to a water bath to be cooled. After lowering to room temperature, stop the rotation and stop the decompression. After replacing the inside of the flask with nitrogen to return it to atmospheric pressure, the eggplant type flask was removed by a rotary evaporator, whereby 100 g of nematic liquid crystal STN1 was obtained. The resistivity of the obtained liquid crystal composition was measured and found to be 1.2 x 1 011 -14 to 200930796 ' Ω cm. The obtained liquid crystal composition was analyzed by gas chromatography, and as a result, substances other than the mixed compound were not mixed, and decomposition of the mixed compound was not observed. The physical properties of the obtained liquid crystal composition were measured, and as a result, the desired properties were obtained. However, it was confirmed that some of the lower molecular weight compounds have volatilized to cause a composition change. In addition, the manufacture must use a pressure reducing device or a heating device that requires a large-scale equipment, and requires a long manufacturing time. [Comparative Example 2] Production of a liquid crystal composition under the atmosphere 制造 The same liquid crystal composition (STN 1 ) as in Example 1 was produced according to the method disclosed in Japanese Laid-Open Patent Publication No. Hei. 5-105876. . Weigh the desired amount of liquid crystal compound in an eggplant type flask. After placing the magnet rotor in the eggplant type flask, it was placed on a hot plate at 50 ° C, and the temperature of the hot plate was raised to 110 ° C at a rate of 5 ° C / min. Rotate the rotor to stir. After the liquid crystal was changed to a liquid state and was transparent for 30 minutes, the heating of the hot plate was stopped and the temperature was slowly returned to room temperature. Thereby, a STN1 of a nematic liquid crystal state of 100 g can be obtained.电阻 The resistivity of the liquid crystal composition obtained was measured and found to be 1.1×1 〇9 Ω cm. The liquid crystal composition obtained by gas chromatography was analyzed, and as a result, a substance other than the mixed compound appeared, and it was found that the liquid crystal compound used for constituting the liquid crystal composition had been oxidatively decomposed. When the liquid crystal upper limit point transfer temperature was measured, the result was reduced to 94.0 ° C, so the deterioration of quality was large. Regarding the preparation method of Comparative Example 2, it was remarkably inferior to the examples in terms of the reliability of the obtained liquid crystal composition. [Example 2] Production of liquid crystal composition -15- 200930796 A liquid crystal composition (TFT 1 and liquid crystal upper limit temperature of 6 8.0 ° C) composed of the lower layer compound was produced.

C3H7~0~^0^0^C2Hs

15g 1〇(TC above 15g 15g 49°C 15g 1〇〇°C above 15g 173°C 15g 166°C 15g 17°C 15g 63°C 15g 56°C 15g 1〇〇°C above 150ml The separated flask was weighed and the amount of each compound as described above and the amount disclosed. The separation flask was placed in a microwave generating device and heated by irradiating microwaves at an output of 1 kW. After irradiation for 10 minutes, The microwave irradiation was stopped. After the separation flask was cooled, it was taken out from the microwave irradiation device, whereby 100 g of the nematic liquid crystal state of the TFT 1 was obtained. The resistivity of the liquid crystal composition obtained was measured and found to be 1.5 X. 1 014 Ω cm. In addition, the liquid crystal composition obtained by gas chromatography was analyzed, and the mixture was not mixed with the substance formed by the mixed compound, and no substance was observed. Decomposition of the mixed compound. The physical properties of the obtained liquid crystal composition were measured, and as a result, the desired characteristics were obtained. The liquid crystal was injected into the TFT panel and the photoelectric characteristics were measured, and as a result, the desired characteristics were obtained. In addition, used in TFT The voltage holding ratio at the time of the board is also sufficiently high. The method of the present invention can produce a high-quality liquid crystal composition in 40 minutes without requiring a large-scale apparatus. According to the results as described above, it can be understood The liquid crystal composition of Example 2 has a very high reliability. © [Comparative Example 3] The liquid crystal composition under reduced pressure is produced according to the method disclosed in Japanese Laid-Open Patent Publication No. 2002-194356. The same liquid crystal composition (TFT1) as in Example 2 was produced. The liquid crystal compound of the desired amount was weighed in an eggplant type flask. Then, the eggplant type flask was mounted on a rotary evaporator. The eggplant type flask was immersed in 50 °. C oil bath and rotate it. Slowly depressurize the rotary evaporator to 20 kPa using a vacuum pump for 5 minutes. Then, set the temperature of the oil bath to 85 ° C and heat up at 5 ° C / min. After the liquid crystal changes to a liquid state and is transparent for 30 minutes, the oil bath is changed to a water bath to be cooled. After lowering to room temperature, the rotation is stopped and the pressure is stopped. The flask is replaced with nitrogen to restore it to After the atmospheric pressure, the eggplant type flask was removed by a rotary evaporator, whereby 100 g of the nematic liquid crystal state of the TFT 1 was obtained. The resistivity of the liquid crystal composition obtained by the measurement was found to be 1.2 x 1 0 14 Ω cm. The obtained liquid crystal composition was analyzed by gas chromatography, and as a result, no substance other than the mixed compound was formed, and decomposition of the mixed compound was not observed. The physical properties of the liquid crystal composition, -17- 200930796 'The result is that we can obtain the characteristics we want. However, it has been confirmed that some of the lower molecular weight compounds have volatilized to cause a composition change. In addition, manufacturing must use a pressure reducing device or a heating device that requires large-scale equipment and requires a long manufacturing time. [Comparative Example 4] Production of a liquid crystal composition in the atmosphere The same liquid crystal composition (TFT 1) as in Example 2 was produced by the method disclosed in Japanese Laid-Open Patent Publication No. Hei. 5-105876. The eggplant type flask was weighed for the desired amount of liquid crystal compound. After placing a magnet rotor in the eggplant type flask, it was placed on a hot plate at 50 ° C, and the temperature of the hot plate was raised to 85 ° C by a surface at a rate of 5 ° C / min. The rotor is rotated to stir. After the liquid crystal was changed to a liquid state and was transparent for 30 minutes, the heating of the hot plate was stopped, and the temperature was slowly returned to room temperature. Thereby, the TFT 1 of the nematic liquid crystal state of 1 gram can be obtained. The resistivity of the obtained liquid crystal composition was measured and found to be 1.3 x 1 013 Ω cm. The liquid crystal composition obtained by gas chromatography was analyzed, and as a result, a substance other than the mixed compound appeared, and it was found that the liquid crystal compound used for constituting the liquid crystal composition had been oxidatively decomposed. When the liquid crystal upper limit point transfer temperature was measured, the result was reduced to 66.8 °c, so the deterioration of quality was large. Regarding the preparation method of Comparative Example 4, it was remarkably inferior to the examples in terms of the reliability of the obtained liquid crystal composition. [Simple description of the diagram] None. [Main component symbol description] &gt;fnr None. -18 -

Claims (1)

200930796 # X. Patent application scope: 1. A method for preparing a liquid crystal composition, characterized in that at least one liquid crystal compound having a melting point higher than 3 Ot is irradiated with microwaves. 2. The method of claim 1 of the patent application, wherein at least two of the liquid crystal compounds have a melting point higher than 30 ° C ° 3 , as in the method of claim 1 of the patent application, wherein the irradiation time of the microwave is 1 Less than an hour. 4. For the production method of the first paragraph of the patent application, it is subjected to microwave irradiation under reduced pressure. 5. For the production method of the first paragraph of the patent application, it is irradiated by microwave under an inert gas atmosphere. 6. The method of claim 1, wherein the temperature at which the microwave is irradiated is in a range from 40 ° C to a liquid crystal phase upper limit temperature of the obtained liquid crystal composition + 50 ° C. 7. In the case of the method of claim 4, an inert gas is used in returning the reduced pressure to atmospheric pressure. ❹ -19- 200930796 VII. Designated representative map: (1) The representative representative of the case is: None. (2) A brief description of the symbol of the representative figure: te 〇 八 8. If there is a chemical formula in this case, please reveal the chemical formula that best shows the characteristics of the invention: ^Ff~ 〇