A method for preparing a violet perylene series pigment

Abstract

The application discloses a preparation method of a purple perylene pigment, which comprises the following steps: under the protection of nitrogen, dissolving inorganic alkali and organic alkali in a polar halogenated aromatic hydrocarbon, heating to 80-120 DEG C under stirring, adding compound 4 and compound 5 after the solid is completely dissolved, heating to 170-190 DEG C after the addition is completed, reacting for 8-14 hours, stopping heating, naturally cooling to room temperature, and obtaining dark red solid through post-treatment; the prepared dark red solid is subjected to ball milling to add ball milling materials to carry out pigmentization processing, and the purple perylene pigment is obtained; the product prepared by the preparation method of the purple perylene pigment is a chemical mixed product, and the color light of the product is consistent with the color light of C.I. Pigment Violet 29 commodity after ball milling processing. Meanwhile, the color light brightness of the product is also consistent with the color light brightness of C.I. Pigment Violet 29 commodity.

Description

TECHNICAL FIELD

[0001] The present invention belongs to the field of preparation of violet organic pigments, and in particular, to a method for preparing C.I. Pigment Violet 29. BACKGROUND

[0002] Perylene pigments are a class of high performance pigments, which have chemical and thermal stability and application performance that are incomparable to ordinary pigments. Most perylene pigments have a color spectrum of bright red, maroon and purple, and C.I. Pigment Violet 29 has a dark purple color spectrum, like other color spectrum varieties of this system, and also has very high light and weather fastness. It has very high migration fastness in plastics and very good re-coating performance in coatings.

[0003] C.I. Pigment Violet 29 (chemical composition 3,4,9,10-perylenetetracarboxylic diimide, compound 1) is a purple variety of perylene pigments, mainly used for the modulation of automobile coatings and the processing of purple plastic products. The traditional method for preparing C.I. Pigment Violet 29 is to react 3,4,9,10-perylenetetracarboxylic dianhydride (compound 2) with ammonia water to obtain 3,4,9,10-perylenetetracarboxylic diimide, and then to perform pigmentization processing to obtain commercial organic pigments (Shen Yongjia, Variety and Application of Organic Pigments, Chemical Industry Press, 2002; H. Zollinger, Color Chemistry, VCH Verlagsgesellschaft, 1991). The problem of the above process is that the manufacturing process of perylene anhydride is very complex, and is roughly as follows: 1,8-naphthalimide (compound 3) is subjected to an alkali fusion reaction at 250°C in molten KOH to become perylene imide, which is then subjected to an oxidation reaction in concentrated sulfuric acid to become perylene anhydride, as shown in Reaction Formula 1 (Willy Herbst, Klaus Hunger, Industrial Organic Pigments: Production, Properties, Applications, 4th, Revised Edition, Wiley-VCH, Weinheim, 2011).

[0004]

[0005] Reaction Formula 1

[0006] The defects of the production of C.I. Pigment Violet 29 described in Reaction Formula 1 are: ① The alkali fusion reaction of 1,8-naphthalimide to generate perylene imide needs to be carried out at 220-250℃. In order to make the reactants have a certain fluidity, the amount of KOH is more than 3 times the weight of 1,8-naphthalimide. Despite this, the viscosity of the reactants is still large, so that the mass transfer between the reactants is not sufficient, and the composition of the alkali fusion reaction product is relatively complex. After the reaction is completed, in order to obtain the desired product, it is necessary to dilute with water, so that perylene imide is precipitated from the dilute alkali solution, thus consuming a large amount of KOH. In order to treat this alkali liquor, a large amount of acid must also be used for neutralization. ② Since the alkali fusion reaction is carried out at 220-250℃, side reactions inevitably occur during the reaction process, so the yield of perylene imide produced by the alkali fusion reaction is less than 50%. ③ After perylene imide is converted into perylene anhydride by oxidation reaction, its purity cannot meet the requirements of subsequent production of pigments, so it needs to be refined by "alkali dissolution-acid precipitation", and a large amount of acid and alkali is consumed in this stage. It can be seen that the traditional method of preparing perylene anhydride has the defects of long reaction steps, high consumption of chemicals and environmental unfriendliness, and is a typical process with high energy consumption, high material consumption and high pollution.

[0007] In order to overcome the defects of Reaction Formula 1, Sakamoto et al. provided a method for preparing perylene imide, which makes 1,8-naphthalimide undergo alkali fusion reaction in potassium tert-butoxide / 1,5-diazabicyclo[4.3.0]-5-nonene (DBN) / diethylene glycol dimethyl ether, which can obtain high-purity perylene imide in high yield, see Reaction Formula 2 (Sakamoto T, Pac C. A "Green" Route to Perylene Dyes: Direct Coupling Reactions of 1,8-Naphthalimide and Related Compounds under Mild Conditions Using a "New" Base Complex Reagent, t-BuOK / DBN [J]. The Journal of organic chemistry, 2001, 66(1): 94-98.).

[0008]

[0009] The research found that the color light of the perylene imide (compound 1) prepared according to the method provided by Sakamoto et al. is inconsistent with the color light of the C.I. Pigment Violet 29 product, so the technology of Sakamoto et al. cannot replace the traditional process to manufacture C.I. Pigment Violet 29. In addition, after the perylene imide obtained from the reaction formula 2 is subjected to the pigmentation processing according to the existing pigmentation technology of C.I. Pigment Violet 29, the color light of the obtained pigment still has a large difference from the color light of the C.I. Pigment Violet 29 product. In retrospect, the synthesis method of the perylene imide provided by Sakamoto et al. has been disclosed since 2001, and more than 20 years have passed so far, but no enterprise manufacturing C.I. Pigment Violet 29 has adopted their technology to manufacture C.I. Pigment Violet 29. In view of this, it is a technical problem to be solved by the present application to provide a method for preparing perylene imide with simple steps and environmental friendliness, and to make the color light consistent with the color light of the C.I. Pigment Violet 29 product after pigmentation processing. SUMMARY

[0010] The purpose of the present application is to provide a preparation method of a purple perylene pigment.

[0011] In order to achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0012] The first aspect of the present application provides a preparation method of a purple perylene pigment, comprising the following steps:

[0013]

[0014] Under nitrogen protection, an inorganic base and an organic base are dissolved in a polar halogenated aromatic hydrocarbon, heated to 80-120°C (preferably 100°C) under stirring, and then compound 4 and compound 5 are added after the solid is completely dissolved. After the addition is completed, the temperature is increased to 170-190°C (preferably 180°C, 190°C), the reaction is carried out for 8-14h (preferably 10h, 12h), the heating is stopped, and the natural cooling to room temperature is carried out. After the post-treatment, a dark red solid is obtained;

[0015] The dark red solid obtained is subjected to pigmentation processing by adding a ball milling agent by a ball milling method to obtain the purple perylene pigment;

[0016] The mass ratio of the dark red solid and the ball milling agent is as follows: the mass ratio of stainless steel beads, dark red solid, anhydrous calcium chloride, butyl acetate and calcium stearate is 50-150:5-10:15-25:2-6:1 (preferably 100:7.5:20:4:1).

[0017] The pigmentation processing of the dark red solid obtained by adding a ball milling agent by a ball milling method comprises the following steps:

[0018] The prepared dark red solid is added into a planetary ball mill, ball milling material (stainless steel beads, anhydrous calcium chloride, butyl acetate, calcium stearate) is added, ball milling is carried out for 3-8 hours (preferably 5 hours), the ball milling material is sieved, the steel beads are sieved out, and then the ball milling material is poured into hot water, stirring is carried out for 0.5-2 hours (preferably 1 hour), and then filtration is carried out, the filter cake is washed with hot water and deionized water until the conductivity of the filtrate is less than 300 microsiemens, and then drying is carried out, so that the purple perylene pigment is obtained.

[0019] The molar ratio of the compound 4 to the compound 5 is 1:0.1-0.5 (preferably 1:0.3).

[0020] The ratio of the total moles of the compound 4 and the compound 5 to the moles of the base is 1:2-10 (preferably 1:6.1, 1:7.3), the base includes an organic base and an inorganic base, and the molar ratio of the organic base to the inorganic base is 1.1-2:1 (preferably 1.37:1, 1.67:1).

[0021] The inorganic base is selected from cesium carbonate, cesium formate, cesium sulfate, cesium hydroxide or a monohydrate thereof, preferably cesium carbonate, cesium formate and a monohydrate thereof.

[0022] The organic base is selected from 1,8-diazabicycloundec-7-ene (DBU), 1,5-diazabicyclo[4.3.0]non-5-ene (DBN) and 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD).

[0023] The polar halogenated aromatic hydrocarbon is selected from o-dichlorobenzene or 1,2,4-trichlorobenzene.

[0024] The mass ratio of the total mass of the compound 4 and the compound 5 to the mass of the polar halogenated aromatic hydrocarbon is 1:2-10 (preferably 1:6.1, 1:6.8).

[0025] The dark red solid obtained through post-treatment includes the following steps: dilution with a C1-C3 monohydric aliphatic alcohol, filtration, washing of the filter cake with the C1-C3 monohydric aliphatic alcohol until no polar halogenated aromatic hydrocarbon is present, and drying to obtain the dark red solid.

[0026] The C1-C3 monohydric aliphatic alcohol is selected from methanol, ethanol and propanol.

[0027] The diameter of the stainless steel beads is 0.2-0.5 cm.

[0028] Thanks to the above technical scheme, the present application has the following advantages and beneficial effects:

[0029] The product prepared by the preparation method of the purple perylene series pigment provided by the application is a chemical mixed product, and after ball milling processing, the color light thereof is consistent with that of the C.I. Pigment Violet 29 product. Meanwhile, the color light brightness thereof is also consistent with that of the C.I. Pigment Violet 29 product.

[0030] The preparation method of the purple perylene series pigment provided by the application is simple and environment-friendly, and the obtained product is subjected to pigmentization processing (ball milling processing) to overcome the defects in the prior art.

[0031] It is found through research that: although the physical color adjusting method can change the color light of the pigment, the color light brightness of the obtained pigment is greatly different from that of the existing C.I. Pigment Violet 29 product, and thus the customer's requirements cannot be met. The application adopts two measures to solve the above technical problems. One is to adopt the “chemical mixing” measure to solve the color light difference problem, and the other is to adopt the ball milling pigmentization technology to solve the color light brightness problem of the pigment. DETAILED DESCRIPTION

[0032] In order to more clearly illustrate the application, the application will be further described below in combination with preferred embodiments. It should be understood by those skilled in the art that the specific description below is illustrative rather than limiting, and should not limit the protection scope of the application.

[0033] The 1,8-naphthalene dicarboximide used in the embodiments of the application is an industrial product produced by Liaoning Lianhang Dyestuff Chemical Co., Ltd. The C.I. Pigment Violet 29 reference product is produced by Liaoning Lianhang Dyestuff Chemical Co., Ltd., and the product brand is Perylene Brilliant Purple Red S-0855. The 1,8-naphthalene anhydride is an industrial product produced by Liaoning Lianhang Dyestuff Chemical Co., Ltd. The p-methoxybenzylamine and cesium carbonate are analytical pure, and are produced by Aladdin Chemical Technology Co., Ltd. The cesium formate is analytical pure, and is produced by Shanghai Shitang Industry Co., Ltd. The potassium tert-butoxide, 1,5-diazabicyclo[4.3.0]non-5-ene (DBN), and 1,8-diazabicycloundec-7-ene (DBU) are all analytical pure, and are produced by Saen Chemical Technology Co., Ltd. The 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) is chemical pure, and is produced by Shanghai Jingfu Biological Technology Co., Ltd. The o-dichlorobenzene and 1,2,4-trichlorobenzene are chemical pure, and are produced by Shanghai Aladdin Reagent Co., Ltd.

[0034] Example 1

[0035]

[0036] The preparation method of the compound 5 comprises the following steps:

[0037] In a 500 mL three-necked flask, under nitrogen protection, add anhydrous ethanol (250 mL), 1,8-naphthalic anhydride (39.6 g, 0.20 mol) and p-methoxybenzylamine (27.4 g, 0.20 mol) under stirring, heat to reflux, react for 3 h, track by silica gel thin plate chromatography (TLC) until the spot of the reaction substrate disappears, stop heating, cool to room temperature naturally, filter, wash the filter cake with ethanol and water successively, dry to obtain pink solid, which is compound 5 (60.2 g), with a yield of 95%.

[0038]

[0039] In a 500 mL round-bottom flask, under nitrogen protection, add cesium carbonate (100.8 g, 0.30 mol), 1,8-diazabicycloundec-7-ene DBU (76.0 g, 0.50 mol) and o-dichlorobenzene (180 g), heat to 100°C under stirring, when the solid is completely dissolved, add 1,8-naphthalimide (compound 4, 19.8 g, 0.10 mol) and N-p-methoxy-1,8-naphthalimide benzylamine (compound 5, 9.51 g, 0.03 mol), after the addition, heat to 180°C to react, track by silica gel thin plate chromatography (TLC) until the spot of the raw material disappears completely (about 12 h are needed), stop heating, cool to room temperature naturally, dilute with methanol to filter to obtain filtrate and filter cake, wash the filter cake with methanol until there is no o-dichlorobenzene smell, and obtain washing liquid. Dry the filter cake to obtain dark red solid (22.5 g). Distill methanol, 1,8-diazabicycloundec-7-ene DBU and o-dichlorobenzene from the filtrate and washing liquid respectively under reduced pressure.

[0040] The dark red solid obtained is a mixture, the main body of the product is perylene imide (compound 1, which is generated by the self-condensation and ring closure of 1,8-naphthalimide). In addition, it also contains the product (compound 3) generated by the self-condensation and ring closure of N-p-methoxy-1,8-naphthalimide benzylamine and the structurally asymmetric product (compound 2) generated by the mixed condensation and ring closure of 1,8-naphthalimide and N-p-methoxy-1,8-naphthalimide benzylamine. After ball milling processing, the color of the dark red solid is the same as that of the commercial C.I. Pigment Violet 29, and the color brilliance of the two is also the same.

[0041] Example 2

[0042] In a 500 mL round bottom flask, cesium carbonate (130.3 g, 0.40 mol), 1,8- diazabicycloundec-7-ene (83.6 g, 0.55 mol) and 1,2,4-trichlorobenzene (200 g) were added under nitrogen protection, heated to 100 °C with stirring, after the solid was completely dissolved, 1,8-naphthalimide (19.8 g, 0.10 mol) and N-p-methoxy-1,8-naphthalimide benzylidene (9.51 g, 0.03 mol) were added, after the addition was completed, the temperature was raised to 190 °C for reaction, TLC tracking until the raw material point disappeared (about 10 h), stop heating, naturally cool to room temperature, dilute with ethanol after filtration to obtain filtrate and filter cake, the filter cake was washed with ethanol until there was no 1,2,4-trichlorobenzene smell, and the washing liquid was obtained. The filter cake was dried to obtain dark red solid (23.2 g). The filtrate and washing liquid were distilled under reduced pressure, respectively, to recover ethanol, 1,8-diazabicycloundec-7-ene DBU, 1,2,4-trichlorobenzene, respectively.

[0043] Example 3

[0044] In a 500 mL round bottom flask, cesium carbonate (130.3 g, 0.40 mol), 1,8- diazabicycloundec-7-ene (83.6 g, 0.55 mol) and 1,2,4-trichlorobenzene (200 g) were added under nitrogen protection, heated to 100 °C with stirring, after the solid was completely dissolved, 1,8-naphthalimide (19.8 g, 0.10 mol) and N-p-methoxy-1,8-naphthalimide benzylidene (9.51 g, 0.03 mol) were added, after the addition was completed, the temperature was raised to 190 °C for reaction, TLC tracking until the raw material point disappeared (about 10 h), stop heating, naturally cool to room temperature, dilute with ethanol after filtration to obtain filtrate and filter cake, the filter cake was washed with ethanol until there was no 1,2,4-trichlorobenzene smell, and the washing liquid was obtained. The filter cake was dried to obtain dark red solid (23.2 g). The filtrate and washing liquid were distilled under reduced pressure, respectively, to recover ethanol, 1,8-diazabicycloundec-7-ene DBU, 1,2,4-trichlorobenzene, respectively.

[0045] Example 4

[0046] In a 500 mL round bottom flask, cesium formate (54.8 g, 0.40 mol), 1,8-diazabicycloundec-7-ene (83.6 g, 0.55 mol) and 1,2,4-trichlorobenzene (200 g) were added under nitrogen protection, and heated to 100 °C with stirring. When the solid was completely dissolved, 1,8-naphthalimide (19.8 g, 0.10 mol) and N-p-methoxy-1,8-naphthalimide benzylidene (9.51 g, 0.03 mol) were added, and the reaction was carried out at 190 °C after the temperature was raised. TLC tracking was performed until the starting material point disappeared (about 10 h). The heating was stopped, and the natural cooling to room temperature was carried out. After dilution with ethanol, the filtrate and filter cake were obtained by filtration. The filter cake was washed with ethanol until there was no 1,2,4-trichlorobenzene odor, and the washing liquid was obtained. After drying, dark red solid (21.2 g) was obtained. The filtrate and washing liquid were distilled under reduced pressure, respectively, and ethanol, 1,8-diazabicycloundec-7-ene DBU, 1,2,4-trichlorobenzene were recovered, respectively.

[0047] Comparative Example 1

[0048] Perylene imide was prepared according to the method described in the literature The Journal of organic chemistry, 2001, 66(1): 94-98.

[0049] In a 100 mL round bottom flask, potassium tert-butoxide (30.3 g, 0.27 mol), 1,5-diazabicyclo[4.3.0]non-5-ene (44.7 g, 0.36 mol) and diethyleneglycol dimethyl ether (90 mL) were added, and heated to 130 °C under nitrogen protection. When the solid was completely dissolved, 1,8-naphthalimide (17.75 g, 0.09 mol) was added, and the reaction was carried out for 3 h after the addition was completed. The heating was stopped, and the cooling to room temperature was carried out. After dilution with diethyleneglycol dimethyl ether, the filter cake was obtained by filtration, and the filter cake was washed with diethyleneglycol dimethyl ether. After drying, dark red solid (13.9 g) was obtained, and the yield was 80%.

[0050] Example 5

[0051] The dark red solid prepared in Examples 1-4 and Comparative Example 1 was respectively subjected to pigmentization processing by ball milling. The formula of the ball milling material is shown in Table 1, and the ball milling was carried out in a planetary ball mill (Nanjing Nantian Instrument Co., Ltd., model QM-3SP2).

[0052] The dark red solid prepared in Examples 1-4 and Comparative Example 1 was added to a planetary ball mill, respectively, and anhydrous calcium chloride, ethyl acetate, calcium stearate, stainless steel beads were added to the ball mill at a rotation speed of 495 rpm for 5 h. After the ball milling, the ball mill was sieved to remove the steel beads, and the ball mill was poured into hot water at 20 times the weight of the ball mill, stirred for 1 h, and filtered. The filter cake was washed with hot water and deionized water until the conductivity of the filtrate was less than 300 μS, and dried at 60°C to constant weight. Pigments 1-5 were obtained, respectively. The products obtained from Examples 1-4 were pigmented to obtain pigments 1-4, and the product obtained from Comparative Example 1 was pigmented to obtain pigment 5.

[0053] Table 1 Ball Milling Table

[0054]

[0055]

[0056] The crude pigments refer to the products obtained from Examples 1-4 and Comparative Example 1.

[0057] The color properties (color shade, tinting strength and brightness) of pigments 1-5 were determined based on a C.I. Pigment Violet 29 commercial product (trade name Perylene Brilliant Violet Red S-0855).

[0058] (1) Preparation of pigment paste:

[0059] A glass bottle with a lid was added with glass beads (diameter 2.5 mm, 60 g), 7.5 g of the sample to be tested (pigment 1-pigment 5), 7.5 g of a dispersant (a mixture of dispersant 24000 (purchased from Lubrizol Specialties Chemicals (Shanghai) Co., Ltd., USA) and butyl acetate at a mass ratio of 1:1), 20 g of a diluent (a mixture of butyl acetate and ethanol at a mass ratio of 1:1), the lid was closed and sealed with tape, and the glass bottle was loaded on a pigment shaker (purchased from Dongguan Wanjiang Weihong Instrument Trading Department) and shaken until the pigment fineness was below 15 μ (detected by a Hegman particle size analyzer), and then 35 g of a diluent (a mixture of butyl acetate and ethanol at a mass ratio of 1:1) was added to obtain a pigment paste.

[0060] (2) Determination of pigment color shade and tinting strength:

[0061] Preparation of color card for determination of pigment color shade: 5 ml of the pigment paste prepared in step (1) was taken with a pipette, dropped on a color card paper, and scraped with a 3K sample scraper to obtain a color card for determination of pigment color shade.

[0062] Preparation of color card for determination of color strength: 5 g of the pigment paste prepared in step (1) was added to 10 g of water-based white paint (white latex paint B1, Shanghai Luban Paint Co., Ltd.) and stirred uniformly with a high-speed stirrer to obtain a pigment-white mixture. 5 ml of the pigment-white mixture was taken with a pipette and dropped on a color card paper, and then scraped with a 3K scraper to obtain a color card for determination of color strength.

[0063] After the color paste on the color card was dried, the color light, color strength and brightness of the pigment were measured with a color difference meter (purchased from Datacolor Company, USA), and the specific results are shown in Tables 2 and 3.

[0064] Table 2. Test data of color light of pigment

[0065]

[0066]

[0067] Table 3. Test data of color strength of pigment

[0068] Test sample L a b K / S value ΔE* Standard sample 52.7 17.1 -12.9 100--- --- Pigment 1 53.07 17.33 -13.16 98.6 <1.5％ Pigment 2 52.77 16.79 -13.09 102.8 <1.5％ Pigment 3 53.78 16.95 -13.20 103 <1.5％ Pigment 4 53.61 16.29 -13.02 103.4 <1.5％ Pigment 5 55.5 13.4 -12.0 64.4 8.3％

[0069] In Tables 2-3, L is brightness, and if the difference between the L value of the measured sample and the standard sample is positive, it means that the measured sample is brighter than the standard sample; otherwise, if the difference is negative, it means that the measured sample is darker than the standard sample. The greater the absolute value of the difference, the greater the degree of deviation.

[0070] a is red-green degree, and if the difference between the a value of the measured sample and the standard sample is positive, it means that the measured sample is reddish; otherwise, if the difference is negative, it means that the measured sample is greenish. The greater the absolute value of the difference, the greater the degree of deviation.

[0071] b is yellow-blue degree, and if the difference between the b value of the measured sample and the standard sample is positive, it means that the measured sample is yellowish; otherwise, if the difference is negative, it means that the measured sample is bluish. The greater the absolute value of the difference, the greater the degree of deviation.

[0072] ΔE* is a comprehensive index of total color difference, and the greater the value, the greater the degree of total color difference. Generally, the qualified value of ΔE* of a sample is between 1% and 2%.

[0073] K / S value is the depth of color, and the greater the value, the higher the color strength.

[0074] The above merely describes the preferred embodiments of the present application, and is not intended to limit the present application in any form. Although the present application has been disclosed with the preferred embodiments as above, it is not intended to limit the present application, and any skilled person in the art can make some changes or modifications to the above-mentioned technical content with the above-mentioned prompt as equivalent embodiments with equivalent changes, but as long as it does not deviate from the technical solution of the present application, any simple modification, equivalent change and modification made to the above embodiments according to the technical essence of the present application are still within the scope of the present application.

Claims

1. A method for preparing a purple perylene pigment, characterized in that, Includes the following steps: ； Under nitrogen protection, inorganic bases and organic bases are dissolved in polar haloaromatic hydrocarbons and heated to 80-120 °C with stirring. When the solid is completely dissolved, compounds 4 and 5 are added. After the addition is complete, the temperature is raised to 170-190 °C and the reaction is carried out for 8-14 h. Heating is stopped and the mixture is allowed to cool naturally to room temperature. After post-treatment, a dark red solid is obtained. The prepared dark red solid was subjected to pigmentation processing by adding ball milling material through ball milling to obtain the purple perylene pigment; The mass ratio of the dark red solid and the abrasive is as follows: the mass ratio of stainless steel beads, dark red solid, anhydrous calcium chloride, butyl acetate, and calcium stearate is 50~150:5~10:15~25:2~6:

1.

2. The method for preparing purple perylene pigment according to claim 1, characterized in that, The pigmentation process of the prepared dark red solid by adding ball milling material includes the following steps: The prepared dark red solid was added to a planetary ball mill, and grinding media was added. The milling process was carried out for 3-8 hours. The grinding media was then sieved to remove steel balls. The mixture was poured into hot water and stirred for 0.5-2 hours. The mixture was then filtered. The filter cake was washed with hot water and deionized water until the conductivity of the filtrate was less than 300 microsiemens. The filtrate was then dried to obtain the purple perylene pigment.

3. The method for preparing purple perylene pigment according to claim 1, characterized in that, The molar ratio of compound 4 to compound 5 is 1:0.1~0.

5.

4. The method for preparing purple perylene pigment according to claim 1, characterized in that, The ratio of the total moles of compounds 4 and 5 to the moles of the base is 1:2 to 10, and the base includes organic bases and inorganic bases, with a molar ratio of organic base to inorganic base of 1.1 to 2:

1.

5. The method for preparing purple perylene pigment according to claim 1, characterized in that, The inorganic base is selected from cesium carbonate.

6. The method for preparing purple perylene pigment according to claim 1, characterized in that, The organic base is selected from 1,8-diazabicycloundec-7-ene, 1,5-diazabicyclo[4.3.0]non-5-ene, and 1,5,7-triazabicyclo[4.4.0]dec-5-ene.

7. The method for preparing purple perylene pigment according to claim 1, characterized in that, The polar halogenated aromatic hydrocarbons are selected from o-dichlorobenzene or 1,2,4-trichlorobenzene.

8. The method for preparing purple perylene pigment according to claim 1, characterized in that, The total mass ratio of compounds 4 and 5 to the mass ratio of polar haloaromatic hydrocarbons is 1:2 to 10.

9. The method for preparing purple perylene pigment according to claim 1, characterized in that, The process of obtaining a dark red solid after post-treatment includes the following steps: diluting with C1-C3 monohydric fatty alcohols and filtering; washing the filter cake with C1-C3 monohydric fatty alcohols until no polar halogenated aromatic hydrocarbons are found; and drying to obtain a dark red solid.

10. The method for preparing purple perylene pigment according to claim 9, characterized in that, The C1~C3 monohydric fatty alcohols are selected from methanol, ethanol, and propanol.

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