Preparation method of pigment violet 23 for engineering plastics

Abstract

This invention belongs to the field of pigment violet preparation technology, and discloses a method for preparing pigment violet 23 for engineering plastics, comprising the following steps: S1: adding tetrachlorobenzoquinone to an organic solvent containing 3-amino-N-ethylcarbazole, then gradually adding a catalyst to react and obtain a condensate, and then using an oxidizing agent to oxidize the obtained condensate; S2: filtering, washing and drying the reaction product obtained in step S1 to obtain the finished pigment violet 23, the product having an extremely rare reddish violet hue, which is more vivid and has stronger tinting strength than ordinary bluish violet, and has excellent temperature resistance, light resistance and migration resistance.

Description

Technical Field

[0001] This invention belongs to the field of pigment violet preparation technology, and specifically relates to a method for preparing pigment violet 23 for engineering plastics. Background Technology

[0002] Pigment Violet 23 is a high-intensity blue-violet dioxazine organic pigment, also known as carbazole violet or dioxazine violet. It possesses excellent overall colorfastness properties, including high-temperature resistance, light and weather resistance, penetration resistance, and good acid and alkali resistance. It is widely used in coatings, printing inks, plastics, and textile dyeing. In coatings, it exhibits good fastness to clear coats and can be used in air-drying paints, automotive OEM coatings, and baking paints. It can also be used as a phthalocyanine blue toner to achieve strong-toned latex paint products. In plastics coloring, it is heat-resistant up to 280℃ in polyolefins and has high tinting strength.

[0003] Patent CN104031400A discloses a method using Cr 6+ Cr 3+ Cu 2+ Using acetates, sulfates, chlorides, and nitrates of iron, cobalt, and nickel as catalysts, and aldehydes such as benzoaldehyde and anthracene as co-catalysts, oxygen is introduced and a pressure of approximately 0.2 MB is maintained. A closed-ring oxidation reaction is carried out at 150-170℃ to obtain crude pigment violet 23. However, the Cr... 6+ Cr 3+ Cu 2+ All of these are heavy metal ions, especially hexavalent chromium, which is a highly toxic heavy metal strictly prohibited by the regulations of various countries. Most of the acetates and sulfates of these metals are insoluble in water and organic solvents, making them difficult to remove by filtration and washing, and ultimately all remain in the pigment. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing pigment violet 23 for engineering plastics. The preparation method of this invention greatly improves the overall yield of the reaction and the purity of the product. Moreover, the product obtained by this method has an extremely rare reddish violet hue, which has higher brightness and stronger tinting strength than ordinary bluish violet, and has excellent temperature resistance, light resistance and migration resistance.

[0005] The above-mentioned technical objective of the present invention is achieved through the following technical solution: a method for preparing pigment violet 23 for engineering plastics, comprising the following steps: S1: adding tetrachlorobenzoquinone to an organic solvent containing 3-amino-N-ethylcarbazole, then gradually adding a catalyst to react and obtain a condensate, and then using an oxidizing agent to oxidize the obtained condensate; S2: filtering, washing and drying the reaction product obtained in step S1 to obtain pigment violet 23 finished product.

[0006] A further provision of the present invention is that the 3-amino-N-ethylcarbazole in step S1 is prepared by reacting 3-nitro-N-ethylcarbazole with sodium sulfide in an ethanol solution.

[0007] A further setting of the present invention is that the molar mass ratio of the 3-nitro-N-ethylcarbazole to sodium sulfide is 2:3-4.

[0008] A further provision of the present invention is that the 3-amino-N-ethylcarbazole comprises the following preparation steps: 3-nitro-N-ethylcarbazole and sodium sulfide solution are gradually added to an ethanol solution with stirring, the temperature is gradually raised to 78-82°C, and the reaction is carried out for 4-5 hours; after the reaction is completed, the mixture is allowed to stand for 30 minutes, and the waste alkali in the lower layer is separated; the upper layer of liquid is placed in a distillation kettle for atmospheric pressure distillation of ethanol, and after distillation, hot water at 68-75°C is gradually added to cause the material to crystallize and precipitate, and then the mixture is cooled to 25°C and discharged into a centrifuge for centrifugation. After thorough drying, 3-amino-N-ethylcarbazole is obtained.

[0009] A further provision of the present invention is that the organic solvent in step S1 is o-dichlorobenzene.

[0010] A further setting of the present invention is that the molar mass ratio of 3-amino-N-ethylcarbazole to tetrachlorobenzoquinone in step S1 is 2:1.

[0011] A further provision of the present invention is that the catalyst in step S1 is triethylamine.

[0012] A further provision of the present invention is that the condensation reaction in step S2 includes the following steps: dissolving an appropriate amount of 3-amino-N-ethylcarbazole in o-dichlorobenzene, heating to 100°C, dehydrating under normal pressure, then cooling the material to about 45°C, starting the stirrer, gradually adding tetrachlorobenzoquinone, keeping the reaction at the temperature for 30 minutes, then cooling to about 30-35°C, adding triethylamine dropwise, and keeping the reaction at the temperature for 4 hours.

[0013] A further setting of the present invention is that the mass ratio of the triethylamine to the 3-amino-N-ethylcarbazole is 1.2-1.5:1.

[0014] A further provision of the present invention is that the oxidant in step S1 is hydrogen peroxide.

[0015] A further provision of the present invention is that the oxidation reaction in step S2 includes the following steps: heating the condensate obtained in step S1 to 115°C, gradually adding hydrogen peroxide, then heating to 125°C, and then holding the reaction at 125°C for 2.5 hours.

[0016] After the reaction is complete, the material in the pot is cooled to 80°C, discharged, and filtered. The mother liquor is then subjected to steam distillation. The distillate condensate is separated into layers, and the aqueous layer is sent to the wastewater treatment system. The filter cake is centrifuged and washed with a 2% bleaching powder solution. The centrifuged washing liquid is then settled in a clear water tank, and the clear water is used for the next batch of water. The wet product is dried to obtain pigment purple 23.

[0017] Step 1: The reaction equation for the preparation of 3-amino-N-ethylcarbazole in step S1:

[0018]

[0019] Step 2: Condensation reaction equation in step S1:

[0020]

[0021] Step 3: Oxidation reaction equation in step S1:

[0022]

[0023] The beneficial effects of this invention are:

[0024] The first step employs a highly efficient, safe, and environmentally friendly atmospheric pressure water system reduction process, avoiding the dangerous high-temperature and high-pressure hydrogenation reduction process. Simultaneously, after ethanol distillation, the distilled ethanol is directly sent to the storage tank for reuse in the next batch, saving energy and raw materials. The second step uses triethylamine as a catalyst, avoiding the use of toxic and harmful metal catalysts, making it more environmentally friendly, efficient, and with extremely high yield. The third step uses hydrogen peroxide for catalytic oxidation, significantly reducing reaction temperature and time while improving reaction efficiency and yield. Furthermore, the reaction only produces products and water, simplifying post-processing, saving energy, and greatly reducing environmental impact. This process significantly improves the overall reaction yield and product purity. The product obtained by this method has an extremely rare reddish-violet hue, which is more vibrant and has stronger tinting strength than typical bluish-violet, and exhibits excellent temperature resistance, lightfastness, and migration resistance. Detailed Implementation

[0025] The technical solutions in the embodiments will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0026] Comparative Example 1:

[0027] A method for preparing pigment Violet 23 for engineering plastics

[0028] Step 1: Add the specified amount of ethanol from the metering tank into the reduction vessel, turn on the reflux cooling water system, add 596.2 kg of 3-nitro-N-ethylcarbazole while stirring, and then add 506.9 kg of 52% sodium sulfide solution. Then turn on the steam and slowly raise the temperature to 80±2℃, and react for 4-5 hours.

[0029] After the reaction is complete, let it stand for 30 minutes, then separate the waste alkali from the lower layer. Place the upper layer into a distillation vessel to distill ethanol at atmospheric pressure, controlling the distillation temperature at approximately 80°C. The distilled ethanol is directly transferred to a storage tank for the next batch. After distillation, turn off the steam, start stirring, and slowly add hot water at approximately 70°C to the vessel to cause crystallization. Then cool to 25°C and discharge into a centrifuge. After thorough drying, the reduced product 3-amino-N-ethylcarbazole is obtained.

[0030] Step 2: Add 117.2 kg of o-dichlorobenzene from the metering tank to the dehydration vessel, then add 550.3 kg of the reduction product 3-amino-N-ethylcarbazole. Seal the vessel, turn on the condenser cooling water, and start the stirrer simultaneously. Turn on the steam in the jacket of the dehydration vessel to raise the temperature to 100°C and dehydrate at atmospheric pressure. After dehydration is complete, turn off the steam, cool the material to about 45°C, pump it into the condensation vessel, start the stirrer, add 200.9 kg of tetrachlorobenzoquinone, and maintain the temperature for 30 minutes. Then cool it to about 34°C, add 149.2 kg of phosphomolybdic acid dropwise over about 1 hour, and after the addition is complete, maintain the temperature for 4 hours.

[0031] Step 3: Start the closed-loop reactor and stir. Put the above condensate directly into the closed-loop reactor and heat it to 125°C with jacketed heat transfer oil. Add 425.3 kg of hydrogen peroxide from the metering tank to the closed-loop reactor. After adding, heat it to 125°C and then keep it at 125°C for 2.5 hours.

[0032] After the reaction, the material in the pot was cooled to 80°C, discharged, and filtered. The mother liquor was then subjected to steam distillation. The distillate condensate was separated into layers, and the aqueous layer was sent to the wastewater treatment system. The filter cake was washed by centrifugation with a 2% pyrrolidone solution. The centrifugal washing liquid was allowed to settle in a clear water tank, and the resulting water was reused for the next batch. The wet product was dried to obtain Pigment Violet 23. The total mass of Pigment Violet 23 obtained was 554.28 kg, with a purity of 85.47% and a yield of 75%.

[0033] Comparative Example 2:

[0034] Step 1: Add the specified amount of ethanol from the metering tank into the reduction vessel, turn on the reflux cooling water system, add 596.2 kg of 3-nitro-N-ethylcarbazole while stirring, and then add 506.9 kg of 52% sodium sulfide solution. Then turn on the steam and slowly raise the temperature to 80±2℃, and react for 4-5 hours.

[0035] After the reaction is complete, let it stand for 30 minutes, then separate the waste alkali from the lower layer. Place the upper layer into a distillation vessel to distill ethanol at atmospheric pressure, controlling the distillation temperature at approximately 80°C. The distilled ethanol is directly transferred to a storage tank for the next batch. After distillation, turn off the steam, start stirring, and slowly add hot water at approximately 70°C to the vessel to cause crystallization. Then cool to 25°C and discharge into a centrifuge. After thorough drying, the reduced product 3-amino-N-ethylcarbazole is obtained.

[0036] Step 2: Add 117.2 kg of o-dichlorobenzene from the metering tank to the dehydration vessel, then add 550.3 kg of the reduction product 3-amino-N-ethylcarbazole. Seal the vessel, turn on the condenser cooling water, and start the stirrer simultaneously. Turn on the steam in the jacket of the dehydration vessel to raise the temperature to 100°C and dehydrate at atmospheric pressure. After dehydration is complete, turn off the steam, cool the material to about 45°C, pump it into the condensation vessel, start the stirrer, add 200.9 kg of tetrachlorobenzoquinone, and maintain the temperature for 30 minutes. Then cool to about 34°C, add 149.2 kg of triethylamine dropwise over about 1 hour. After the dropwise addition is complete, maintain the temperature for 4 hours.

[0037] Step 3: Start the closed-loop reactor and stir. Put the above condensate directly into the closed-loop reactor and heat it to 125°C with jacketed heat transfer oil. Continuously introduce oxygen into the closed-loop reactor and then keep it at 125°C for 2.5 hours.

[0038] After the reaction, the material in the pot was cooled to 80°C, discharged, and filtered. The mother liquor was subjected to steam distillation. The distillate condensate was separated into layers, and the aqueous layer was sent to the wastewater treatment system. The filter cake was washed by centrifugation with a 2% pyrrolidone solution. The centrifugal washing liquid was allowed to settle in a clear water tank, and the clear water was reused for the next batch. The wet product was dried to obtain Pigment Violet 23. The mass of Pigment Violet 23 obtained was 674.45 kg, the purity was 89.48%, and the yield was 92%.

[0039] Example 1:

[0040] Step 1: Add the specified amount of ethanol from the metering tank into the reduction vessel, turn on the reflux cooling water system, add 596.2 kg of 3-nitro-N-ethylcarbazole while stirring, and then add 506.9 kg of 52% sodium sulfide solution. Then turn on the steam and slowly raise the temperature to 80°C, reacting for 4-5 hours.

[0041] After the reaction is complete, let it stand for 30 minutes, then separate the waste alkali from the lower layer. Place the upper layer into a distillation vessel to distill ethanol at atmospheric pressure, controlling the distillation temperature at approximately 80°C. The distilled ethanol is directly transferred to a storage tank for the next batch. After distillation, turn off the steam, start stirring, and slowly add hot water at approximately 70°C to the vessel to cause crystallization. Then cool to 25°C and discharge into a centrifuge. After thorough drying, the reduced product 3-amino-N-ethylcarbazole is obtained.

[0042] Step 2: Add 117.2 kg of o-dichlorobenzene from the metering tank to the dehydration vessel, then add 550.3 kg of the reduction product 3-amino-N-ethylcarbazole. Seal the vessel, turn on the condenser cooling water, and start the stirrer simultaneously. Turn on the steam in the jacket of the dehydration vessel to raise the temperature to 100°C and dehydrate at atmospheric pressure. After dehydration is complete, turn off the steam, cool the material to about 45°C, pump it into the condensation vessel, start the stirrer, add 200.9 kg of tetrachlorobenzoquinone, and maintain the temperature for 30 minutes. Then cool to about 34°C, add 149.2 kg of triethylamine dropwise over about 1 hour. After the dropwise addition is complete, maintain the temperature for 4 hours.

[0043] Step 3: Start the closed-loop reactor and stir. Put the above condensate directly into the closed-loop reactor and heat it to 115°C with jacketed heat transfer oil. Add 425.3 kg of hydrogen peroxide from the metering tank to the closed-loop reactor. After adding, heat it to 125°C and then keep it at 125°C for 2.5 hours.

[0044] After the reaction, the material in the pot was cooled to 80°C, discharged, and filtered. The mother liquor was subjected to steam distillation. The distillate condensate was separated into layers, and the aqueous layer was sent to the wastewater treatment system. The filter cake was washed by centrifugation with a 2% pyrrolidone solution. The centrifugal washing liquid was allowed to settle in a clear water tank, and the clear water was reused for the next batch. The wet product was dried to obtain Pigment Violet 23. The total mass of Pigment Violet 23 obtained was 721.47 kg, with a purity of 99% and a yield of 98.7%.

[0045] Example 2:

[0046] Step 1: Add the specified amount of ethanol from the metering tank into the reduction vessel, turn on the reflux cooling water system, add 596.2 kg of 3-nitro-N-ethylcarbazole while stirring, and then add 522.5 kg of 52% sodium sulfide solution. Then turn on the steam and slowly raise the temperature to 80°C, reacting for 4-5 hours.

[0047] After the reaction is complete, let it stand for 30 minutes, then separate the waste alkali from the lower layer. Place the upper layer into a distillation vessel to distill ethanol at atmospheric pressure, controlling the distillation temperature at approximately 80°C. The distilled ethanol is directly transferred to a storage tank for the next batch. After distillation, turn off the steam, start stirring, and slowly add hot water at approximately 70°C to the vessel to cause crystallization. Then cool to 25°C and discharge into a centrifuge. After thorough drying, the reduced product 3-amino-N-ethylcarbazole is obtained.

[0048] Step 2: Add 117.2 kg of o-dichlorobenzene from the metering tank to the dehydration vessel, then add 550.3 kg of the reduction product 3-amino-N-ethylcarbazole. Seal the vessel, turn on the condenser cooling water, and start the stirrer simultaneously. Turn on the steam in the jacket of the dehydration vessel to raise the temperature to 100°C and dehydrate at atmospheric pressure. After dehydration is complete, turn off the steam, cool the material to about 45°C, pump it into the condensation vessel, start the stirrer, add 200.9 kg of tetrachlorobenzoquinone, and maintain the temperature for 30 min. Then cool to about 34°C, and add 149.2 kg of triethylamine (catalyst) dropwise over about 1 hour. After the addition is complete, maintain the temperature for 4 hours.

[0049] Step 3: Start the closed-loop reactor and stir. Put the above condensate directly into the closed-loop reactor and heat it to 115°C with jacketed heat transfer oil. Add 425.3 kg of hydrogen peroxide from the metering tank to the closed-loop reactor. After adding, heat it to 125°C and then keep it at 125°C for 2.5 hours.

[0050] After the reaction, the material in the pot was cooled to 80°C, discharged, and filtered. The mother liquor was then subjected to steam distillation. The distillate condensate was separated into layers, and the aqueous layer was sent to the wastewater treatment system. The filter cake was washed by centrifugation with a 2% pyrrolidone solution. The centrifugal washing liquid was allowed to settle in a clear water tank, and the purified water was reused for the next batch. The wet product was dried to obtain Pigment Violet 23. The total mass of Pigment Violet 23 obtained was 723.67 kg, with a purity of 99% and a yield of 99%.

[0051] Example 3:

[0052] Step 1: Add the specified amount of ethanol from the metering tank into the reduction vessel, turn on the reflux cooling water system, add 596.2 kg of 3-nitro-N-ethylcarbazole while stirring, and then add 500.7 kg of 52% sodium sulfide solution. Then turn on the steam and slowly raise the temperature to 82°C, reacting for 4-5 hours.

[0053] After the reaction is complete, let it stand for 30 minutes, then separate the waste alkali from the lower layer. Place the upper layer into a distillation vessel to distill ethanol at atmospheric pressure, controlling the distillation temperature at approximately 80°C. The distilled ethanol is directly transferred to a storage tank for the next batch. After distillation, turn off the steam, start stirring, and slowly add hot water at approximately 70°C to the vessel to cause crystallization. Then cool to 25°C and discharge into a centrifuge. After thorough drying, the reduced product 3-amino-N-ethylcarbazole is obtained.

[0054] Step 2: Add 117.2 kg of o-dichlorobenzene from the metering tank to the dehydration vessel, then add 550.3 kg of the reduction product 3-amino-N-ethylcarbazole. Seal the vessel, turn on the condenser cooling water, and start the stirrer simultaneously. Turn on the steam in the dehydration vessel jacket to raise the temperature to 100°C and dehydrate at atmospheric pressure. After dehydration, turn off the steam and cool the material to about 45°C. Pump it into the condensation vessel, start the stirrer, and add 200.9 kg of tetrachlorobenzoquinone. Maintain the temperature for 30 minutes. Then cool it to about 34°C and add 150.2 kg of triethylamine dropwise over about 1 hour. After the addition is complete, maintain the temperature for 4 hours.

[0055] Step 3: Start the closed-loop reactor stirring, put the above condensate directly into the closed-loop reactor, heat it to 115°C with jacketed heat transfer oil, add 422.3 kg of hydrogen peroxide from the metering tank into the closed-loop reactor, and after adding it, heat it to 125°C, and then keep it at 125°C for 2.5 h.

[0056] After the reaction, the material in the pot was cooled to 80°C, discharged, and filtered. The mother liquor was then subjected to steam distillation. The distillate condensate was separated into layers, and the aqueous layer was sent to the wastewater treatment system. The filter cake was washed by centrifugation with a 2% pyrrolidone solution. The centrifugal washing liquid was allowed to settle in a clear water tank, and the purified water was used for the next batch. The wet product was dried to obtain Pigment Violet 23. The total mass of Pigment Violet 23 obtained was 716.36 kg, with a purity of 99% and a yield of 98%.

Claims

1. A method for preparing pigment Violet 23 for engineering plastics, characterized in that: Includes the following steps: S1: Tetrachlorobenzoquinone is added to an organic solvent containing 3-amino-N-ethylcarbazole, and then a catalyst is gradually added dropwise to react and obtain a condensate. The condensate is then oxidized using an oxidizing agent. The oxidant in step S1 is hydrogen peroxide; The catalyst in step S1 is triethylamine; S2: The reaction product obtained in step S1 is filtered, washed, and dried to obtain pigment violet 23.

2. The method for preparing pigment violet 23 for engineering plastics according to claim 1, characterized in that: The 3-amino-N-ethylcarbazole in step S1 is prepared by reacting 3-nitro-N-ethylcarbazole with sodium sulfide in an ethanol solution.

3. The method for preparing pigment violet 23 for engineering plastics according to claim 2, characterized in that: The molar mass ratio of 3-nitro-N-ethylcarbazole to sodium sulfide is 2:3-4.

4. The method for preparing pigment violet 23 for engineering plastics according to claim 1, characterized in that: The 3-amino-N-ethylcarbazole comprises the following preparation steps: 3-nitro-N-ethylcarbazole and sodium sulfide solution are gradually added to an ethanol solution with stirring, and the temperature is gradually raised to 78-82℃, and the reaction is carried out for 4-5 hours; after the reaction is completed, the mixture is allowed to stand for 30 minutes, and the waste alkali in the lower layer is separated; the upper layer of liquid is placed in a distillation kettle to distill ethanol at atmospheric pressure. After distillation, hot water at 68-75℃ is gradually added to cause the material to crystallize and precipitate, and then the mixture is cooled to 25℃ and discharged into a centrifuge for centrifugation. After thorough drying, 3-amino-N-ethylcarbazole is obtained.

5. The method for preparing pigment violet 23 for engineering plastics according to claim 1, characterized in that: The organic solvent in step S1 is o-dichlorobenzene.

6. The method for preparing pigment violet 23 for engineering plastics according to claim 1, characterized in that: In step S1, the molar mass ratio of 3-amino-N-ethylcarbazole to tetrachlorobenzoquinone is 2:

1.

7. The method for preparing pigment violet 23 for engineering plastics according to claim 1, characterized in that: The specific preparation steps for adding tetrachlorobenzoquinone to an organic solvent containing 3-amino-N-ethylcarbazole in step S1, and then gradually adding a catalyst to react and obtain the condensate are as follows: Dissolve an appropriate amount of 3-amino-N-ethylcarbazole in o-dichlorobenzene, heat to 100°C, dehydrate under normal pressure, then cool the material to 45°C, start stirring, gradually add tetrachlorobenzoquinone, keep the reaction at this temperature for 30 min, then cool to 30-35°C, add triethylamine dropwise, and keep the reaction at this temperature for 4 h.

8. The method for preparing pigment violet 23 for engineering plastics according to claim 1, characterized in that: The oxidation reaction in step S1 includes the following steps: heating the condensate obtained in step S1 to 115°C, gradually adding hydrogen peroxide, then heating to 125°C, and then holding the reaction at 125°C for 2.5 hours.

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