Purification method of organic pigment for color filter, nanoscale organic pigment and preparation method of nanoscale organic pigment

Abstract

The invention belongs to the field of electronic chemicals, and particularly relates to a purification method of an organic pigment for a color filter, a nanoscale organic pigment and a preparation method of the nanoscale organic pigment. The purification method comprises the step of extracting a pigment crude product by adopting supercritical CO2 fluid, wherein the carrying agent is selected from at least one of methanol, ethanol, dichlorobenzene, dimethylacetamide and dimethylformamide. And carrying out simple micronization treatment on the purified organic pigment to obtain high-purity nanoscale crystal particles. According to the invention, the preparation of the high-purity organic pigment can be realized, the difficulty of preparing the nanoscale organic pigment is greatly reduced, the obtained pigment is bright in colored light, controllable in particle size and narrow in particle size range, and can be used in a dispersion liquid of a color filter, the color purity, the brightness and the contrast ratio are greatly improved, and good viscosity stability can be maintained.

Description

Technical Field

[0001] The invention belongs to the field of electronic chemicals, and in particular relates to a purification method of an organic pigment used for a color filter, a nano-scale organic pigment and a preparation method thereof. Background Art

[0002] In the liquid crystal display (LCD) industry, the performance of color filters, as core components, is mainly determined by the raw material photoresist properties of its color layer and the coating process, which directly affects the contrast, brightness, viewing angle and even picture quality of the display. Photoresist is an important material for color filters, and the core of photoresist is pigment dispersion. Therefore, the particle size and dispersion state of the pigment directly determine the color quality of the end product.

[0003] As one of the most important factors affecting colorants, organic pigments are required to have outstanding spectral properties such as a wide emission band, low transmittance at a specific absorption wavelength, and high transmittance at a transmission wavelength, as well as good dispersibility and storage stability. Therefore, the pigment product must be as pure and small as possible, and can be evenly and stably dispersed in the medium. At present, high-performance organic pigments are mainly used, and most of them are micronized in different ways for the pigment matrix to obtain a manufacturing technology with a particle size in the nano-controllable level range. Chinese invention patent application CN201110113100.1 is to treat the crude pigment and acid, then add a crystal stabilizer and an organic solvent to the solvent phase to obtain the pigment, and then add an appropriate amount of derivatives to mix to obtain a yellow composition product. Chinese invention patent application CN201810908826.6 synthesized a derivative auxiliary agent, which adheres to the surface of the pigment and effectively improves the dispersibility of the pigment. Chinese invention patent application CNCN201010255584.9 is to wash the crude pigment with DMF and ethanol, then grind, knead or solvent treat the obtained pigment, and add derivatives in time to finally obtain a yellow pigment product. None of the above methods effectively purifies the crude pigment. Chinese invention patent application CN202211487969.7 is to contact the subcritical solution fluid of the pigment with supercritical CO2 to precipitate organic pigment nanocrystals. Invention patent US6358308B2 treats organic pigments through the interaction between crude organic pigments and liquid or supercritical CO2, with the aim of avoiding the safety risks brought about by the use of a large amount of flammable solvents in the pigmentation process, while reducing the large amount of energy consumed by high temperature and high pressure reactions and solvent recovery. The latter two patents use supercritical CO2, and their purpose is also to control the size of the pigment particles, and do not improve the purity of the pigment.

[0004] In all the above methods, no matter what method is adopted, the purpose is to intervene in the size of pigment particles, but the purity of the pigment has not been improved. Because some colored byproducts produced by high-performance organic pigments and their reaction processes are basically insoluble in most organic solvents under normal pressure, impurities will be wrapped in the pigment. The crude product is used as a matrix for particle nano-crystallization. Due to its complex components and physical structure, it will greatly increase the difficulty of crystallization; at the same time, due to the influence of impurities, the resulting pigment particles will also have various shapes, poor uniformity and stability, thereby affecting the use effect, and cannot truly fully meet the use requirements in the field of photoresists. Chinese invention patent application CN202211487969.7 aims to prepare nanoscale pigment crystal particles. However, due to the extremely low solubility of pigments in organic solvents, this method will use an extremely large amount of solvent, the production capacity is too low, and it also fails to avoid the influence of impurities entrained in the crude pigment on the performance. Invention patent US6358308B2 is also interfered by impurities in the crude pigment, and the quality of the resulting pigment is poor.

[0005] In summary, in the prior art, impurities in the crude pigment cannot be effectively separated, thus affecting the preparation and use of nano-scale pigments. In view of this, it is particularly important to develop a new purification and nano-scale method. Summary of the invention

[0006] In view of the deficiencies in the prior art, the present invention provides a method for purifying an organic pigment for a color filter, a nano-scale organic pigment and a preparation method thereof.

[0007] In order to achieve the purpose of the present invention, the technical solution adopted is as follows:

[0008] A method for purifying an organic pigment for a color filter, the extraction method comprising: extracting a crude pigment using a supercritical CO2 fluid, and retaining the purified pigment; wherein the carrying agent is selected from at least one of methanol, ethanol, dichlorobenzene, dimethylacetamide, and dimethylformamide.

[0009] Preferably, the carrying agent is selected from methanol.

[0010] Preferably, the extraction pressure is 10-33 MPa, and / or the extraction temperature is 25-55° C., and / or the extraction time is 60 min-300 min, and the CO2 flow rate is 14-23 L / h.

[0011] Preferably, the volume ratio of the crude pigment to the carrying agent is 0.5-5:1.

[0012] Preferably, the extraction pressure is 27-30 MPa, and / or the extraction temperature is 45-50° C., and / or the extraction time is 120-150 min, and the CO2 flow rate is 21 L / h.

[0013] The above purification method is suitable for a variety of high-performance organic pigment crude products, including pyrrolopyrrole dione (PR254, PR291), quinacridone (PR122, PR202, PV19), phthalocyanine pigments (PB15:6, PB15:4, PG36, PG58, PG7), isoindolinone (PY109, PY110), isoindolinone (PY139, PY185), dioxazine (PV23), anthraquinone (PR177), pyrimidine heterocycle (PY150) and other high-performance pigments. For different pigments, the carrier is extended to isopropanol, n-butanol, chlorobenzene, glacial acetic acid, dimethyl sulfoxide, dichloroethane, dichloromethane, and the optimal value range of other parameters will also be different.

[0014] The second purpose of the present invention is to provide a method for preparing high-purity nano-scale organic pigments for color filters. The crude organic pigment is placed in an extraction tank, a carrier is mixed with supercritical CO2, and then contacted with the organic pigment in the extraction tank at a certain pressure, flow rate, and temperature. The supercritical CO2 and the carrier take away impurities in the pigment. The purified organic pigment is then subjected to a simple micronization process to obtain high-purity nano-scale crystal particles.

[0015] Preferably, the preparation method comprises the following steps:

[0016] (1) adding an organic solvent and a strong alkaline reagent to the organic pigment purified by the above purification method to carry out a salt-forming reaction;

[0017] (2) then adding an acid solvent for acid precipitation;

[0018] (3) Heating, keeping warm, and filtering.

[0019] Preferably, the organic solvent in step (1) is at least one selected from methanol, ethanol, isopropanol, n-butanol, DMF, DMAC, dichlorobenzene, chlorobenzene, toluene, and N-methylpyrrolidone;

[0020] Preferably, the strong base reagent is selected from at least one of sodium methoxide, lithium methoxide, sodium ethoxide, lithium ethoxide, butyl lithium, lithium diisopropylamide, benzyl lithium, potassium amide and sodium amide.

[0021] Preferably, the organic solvent in step (1) is selected from methanol or dichlorobenzene;

[0022] Preferably, the strong base reagent in step (1) is selected from sodium methoxide, lithium methoxide or butyl lithium.

[0023] Preferably, the salt-forming temperature in step (1) is 20 to 60° C., and the salt-forming time is 20 to 120 minutes;

[0024] Preferably, the acid in step (2) is selected from formic acid or acetic acid;

[0025] Preferably, the insulation temperature in step (3) is 64 to 130° C., and the insulation time is 2 to 5 hours.

[0026] Another object of the present invention is to provide a high-purity nano-scale organic pigment for color filter prepared by the above preparation method.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention provides a new method for purifying high-performance pigments. After the pigments are purified, they are simply nanosized to obtain pigment crystal particles with good performance, which solves the problem of the influence of impurities in the pigments that are difficult to remove on the overall performance of the pigments. Compared with the existing methods, the viscosity and stability of the color paste are well maintained, the film thickness of the color filter is thinned, and the brightness and contrast are greatly improved, which can fully meet the use in the field of photoresists.

[0029] (2) After the pigment is purified, the present invention can make the pigment nano-process simple and easy to obtain; compared with the existing method, due to the previous purification process, the micronization technology is relatively simple and easy to obtain, and only alkali dissolution, acid precipitation, heat preservation and shaping are required. No mechanical treatment such as grinding and kneading is required, nor is a crystal inducing agent or high temperature and high pressure treatment in an organic solvent required.

[0030] (3) The present invention adopts the pigment purified and nanosized by the present invention, and the quality (film thickness, brightness, contrast, viscosity stability) is significantly improved; it truly meets the use requirements in the field of photoresists (pigments prepared by other methods basically cannot meet the use requirements in the field of photoresists). DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with specific implementation modes.

[0032] Example 1

[0033] Purification of crude organic pigments:

[0034] 300 g of crude powder of quinophthalone yellow PY138 pigment is placed in an extraction tank, ethanol is used as a carrier, extraction pressure is 27 MPa, extraction temperature is 40°C, volume ratio of pigment to ethanol is 1:2, CO2 flow rate is 15 L / h, extraction time is 90 min, and purified pigment is obtained.

[0035] Preparation method of high-purity nano-scale organic pigments for color filters:

[0036] 30g of the purified pigment was placed in 600ml of ethanol and dispersed evenly. Then butyl lithium was added dropwise at 35℃ for salt formation reaction, the salt formation time was 30min, and stirred for 20min. Acetic acid was added for acid precipitation. After all the pigment was precipitated, the temperature was adjusted to 70℃ and kept warm for 2h. Then it was filtered, washed and dried to obtain sample A.

[0037] Example 2

[0038] Preparation method of high-purity nano-scale organic pigments for color filters:

[0039] 30g of the pigment purified in Example 1 was placed in 600ml of methanol and dispersed evenly. Then sodium methoxide was added dropwise at 50-55°C for 60min of salt formation reaction and stirred for 20min. Formic acid was then added for acid precipitation. After all the pigment was precipitated, the temperature was adjusted to 64°C and kept warm for 3h. Then it was filtered, washed and dried to obtain sample B.

[0040] Example 3

[0041] Purification of crude organic pigments:

[0042] 300g of crude powder of quinophthalone yellow PY138 pigment was placed in an extraction tank, methanol was used as the carrier, extraction pressure was 30MPa, extraction temperature was 50℃, volume ratio of pigment to methanol was 5:2, CO2 flow rate was 21L / h, extraction time was 132min. Purified product C was obtained. * .

[0043] Preparation method of high-purity nano-scale organic pigments for color filters:

[0044] 30g of the purified pigment obtained above was placed in 600ml of dichlorobenzene and dispersed evenly. Then sodium methoxide was added dropwise at 55℃ for salt formation reaction, the salt formation time was 70min, and stirred for 20min. Acetic acid was added for acid precipitation. After all the pigment was precipitated, the temperature was adjusted to 110℃ and kept warm for 2h. Then it was filtered, washed and dried to obtain sample C.

[0045] Example 4

[0046] Preparation method of high-purity nano-scale organic pigments for color filters:

[0047] The purified pigment C obtained in Example 3 * 30g, dispersed evenly in 600ml DMAC, then added sodium ethoxide dropwise at 50℃ for salt formation reaction, the salt formation time was 60min, and stirred for 20min. Then acetic acid was added for acid precipitation, and after all the pigment was precipitated, the temperature was adjusted to 100℃ and kept warm for 2h. Then filtered, washed and dried to obtain sample D.

[0048] Example 5

[0049] 1) 300 g of crude powder of quinophthalone yellow PY138 pigment was placed in an extraction tank, PhCl2 was selected as the carrier, the extraction pressure was 28 MPa, the extraction temperature was 48°C, the volume ratio of pigment to PhCl2 was 3:1, the CO2 flow rate was 20 L / h, and the extraction time was 145 min.

[0050] 2) The purified pigment obtained above was treated according to the preparation method of high-purity nano-scale organic pigment for color filter in Example 3 to obtain sample E.

[0051] Comparative Example 1

[0052] The only difference from Example 3 is that the pigment is directly nanosized without purification.

[0053] 30g of crude quinophthalone yellow PY138 pigment was placed in 600ml of dichlorobenzene and dispersed evenly according to the preparation method of high-purity nano-scale organic pigment for color filter in Example 3. Then sodium methoxide was added dropwise at 55°C for salt formation reaction, the salt formation time was 70min, and stirred for 20min. Acetic acid was added for acid precipitation, and after all the pigment was precipitated, the temperature was adjusted to 110°C and kept warm for 2h. Then it was filtered, washed and dried to obtain sample F.

[0054] Comparative Example 2

[0055] The same as Example 3, the only difference is the purification method. Specifically, 300 g of crude powder of quinophthalone yellow PY138 pigment is placed in an extraction cylinder, n-butanol is selected as a carrier, the extraction pressure is 33 MPa, the extraction temperature is 53° C., the volume ratio of pigment to n-butanol is 5:2, the CO2 flow rate is 21 L / h, and the extraction time is 180 min. The purified product G* is obtained. The extraction conditions are the optimal parameters under the n-butanol carrier.

[0056] Then, 30g of the purified pigment obtained above was placed in 600ml of dichlorobenzene and dispersed evenly. Then, sodium methoxide was added dropwise at 55°C for salt formation reaction, the salt formation time was 70min, and stirred for 20min. Then, acetic acid was added for acid precipitation. After all the pigment was precipitated, the temperature was adjusted to 110°C and kept warm for 2h. Then, it was filtered, washed, and dried to obtain sample G.

[0057] Comparative Example 3

[0058] The same as Example 3, the only difference is that the preparation method of the high-purity nano-scale organic pigment used for the color filter is different.

[0059] 30g of the purified pigment C* obtained in Example 3 was placed in 600ml of N-methylpyrrolidone and dispersed evenly. Then sodium amide was added dropwise at 28°C for salt formation reaction, the salt formation time was 70min, and stirred for 20min. Acetic acid was then added for acid precipitation. After all the pigment was precipitated, the temperature was adjusted to 130°C and kept warm for 4h. Then it was filtered, washed, and dried to obtain sample H.

[0060] Comparative Example 4

[0061] According to the method of patent 201110113100.1, the amount of raw materials used was reduced by 1000 times to obtain pigment sample I.

[0062] Comparative Example 5

[0063] Pigment sample J was prepared according to the method of Example 1 of Patent 201010255584.9.

[0064] Comparative Example 6

[0065] According to the method of Example 16 of patent US6358308B2, pigment sample K was prepared.

[0066] Comparative Example 7

[0067] According to the method of patent 202211487969.7, since the solubility of quinophthalone yellow PY138 in most organic solvents is extremely low (≤ppm level), it is impossible to select a suitable solvent as a good solvent to dissolve the pigment, and the product cannot be obtained by this method.

[0068] The quinophthalone yellow PY138 samples obtained in the above examples and comparative examples were respectively prepared and tested according to the mixing method of the color paste. The performance comparison data thereof are shown in Tables 1 and 2 below.

[0069] Among them, the mixing method of color paste is as follows:

[0070] 1.65 g of the above pigment, 3.85 g of dispersant DISPERBYK-161 (solid content 30% by mass), 11.0 g of propylene glycol monomethyl ether acetate, and 38 g of 0.3 mm zirconium beads were mixed and dispersed in a paint shaker for 2 hours to obtain a dispersion. 4 g of the dispersion was added with 0.98 g of UNDIC ZL-295 (solid content 40% by mass) and 0.22 g of propylene glycol monomethyl ether acetate, and mixed in a paint shaker to obtain a color paste for evaluation.

[0071] The sample preparation and testing method is as follows:

[0072] Take 1 ml of the evaluation color paste and spin-coat it on a standard glass slide at a speed of 1500 rpm. Heat the coated glass slide at 150°C for 15 minutes and measure the color with a Datecolor colorimeter. Dry it at 230°C for 60 minutes, measure the color and chromaticity (x, y), contrast (CR), film thickness, and calculate the brightness (Y). The particle size is tested by a nanoparticle sizer, and the viscosity is tested by a Brookfield high-precision Brookfield rotational viscometer DVNEXT.

[0073] Table 1

[0074]

[0075] The above table shows the color difference change of the color filter after coating at different temperatures. The smaller the △E difference, the less the pigment is affected by temperature and the higher the purity. The smaller the D50, D90 data and their difference, the smaller the pigment particle size and the narrower the particle size distribution. The pigment crystallinity is better and it is easier to form a uniform and stable color paste.

[0076] Table 2

[0077]

[0078]

[0079] In the above table, the higher the Y (brightness) and CR (contrast), the thinner the film thickness, and the lower the viscosity, the more suitable the corresponding pigment is for use in the photoresist field.

[0080] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A method for purifying an organic pigment for a color filter, characterized in that: The purification method comprises: extracting the crude pigment by supercritical CO2 fluid, and retaining the purified pigment; wherein the carrying agent is selected from at least one of methanol, ethanol, dichlorobenzene, dimethylacetamide, and dimethylformamide.

2. The extraction method according to claim 1, characterized in that The carrying agent is selected from methanol.

3. The extraction method according to claim 1, characterized in that The extraction pressure is 10-33 MPa, and / or the extraction temperature is 25-55° C., and / or the extraction time is 60 min-300 min, and the CO2 flow rate is 14-23 L / h.

4. The extraction method according to claim 1, characterized in that The volume ratio of the crude pigment to the carrier is 0.5-5:1; the crude pigment is selected from quinophthalone yellow, dione pyrrolopyrrole, quinacridone, phthalocyanine pigment, isoindolinone, isoindolinone, dioxazine, anthraquinone or pyrimidine heterocycle.

5. The extraction method according to claim 1, characterized in that The extraction pressure is 27-30 MPa, the extraction temperature is 45-50° C., the extraction time is 120-150 min, and the CO2 flow rate is 20-22 L / h.

6. A method for preparing high-purity nanoscale organic pigments for color filters, characterized in that: The steps include: (1) adding an organic solvent and a strong alkaline reagent to the organic pigment purified by the purification method according to any one of claims 1 to 5 to carry out a reaction; (2) then adding an acid solvent for acid precipitation; (3) Heating, keeping warm, and filtering.

7. The preparation method according to claim 6, characterized in that: The organic solvent in step (1) is selected from at least one of methanol, ethanol, isopropanol, n-butanol, dichlorobenzene, dimethylacetamide, dimethylformamide, chlorobenzene and toluene; and / or the strong base reagent is selected from at least one of sodium methoxide, lithium methoxide, sodium ethoxide, lithium ethoxide, butyl lithium, lithium diisopropylamide, benzyl lithium, potassium amide and sodium amide.

8. The preparation method according to claim 6, characterized in that: The organic solvent in step (1) is selected from methanol or dichlorobenzene, and / or the strong base reagent in step (1) is selected from sodium methoxide, lithium methoxide or butyl lithium.

9. The preparation method according to claim 6, characterized in that: The reaction temperature in step (1) is 20 to 60° C., the reaction time is 20 to 120 min, the acid in step (2) is selected from formic acid or acetic acid; and / or the temperature in step (3) is raised to 64 to 130° C. and then kept warm for 2 to 5 h.

10. A nanoscale organic pigment prepared by the preparation method according to any one of claims 6 to 9.

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