A method for preparing an organic pigment for coatings based on golden red

Abstract

The invention discloses a method for preparing an organic pigment for coatings based on jinguanghong, belonging to the technical field of pigment synthesis. The method comprises the following steps: firstly, 2-amino-5-chloro-4-methylbenzenesulfonic acid is diazotized, and then coupled with a terminal olefin-modified silica-naphthol derivative, and then a barium chloride aqueous solution is added for lake formation to obtain a terminal olefin-modified jinguanghong pigment, and finally the pigment is reacted with polyvinyl acetate to obtain the jinguanghong pigment. The preparation method of the invention significantly improves the dispersion stability, moisture resistance, migration resistance and solvent resistance of the pigment, and enhances its application performance in coatings.

Description

Technical Field

[0001] The invention belongs to the technical field of pigment synthesis, and in particular relates to a method for preparing an organic pigment for coatings based on golden red. Background Art

[0002] Golden Red (CI PR 53:1) is a barium salt lake pigment with good thermal stability, light resistance, acid and alkali resistance and dyeing power. It is widely used in inks, plastics and rubber products.

[0003] However, due to its structural characteristics, Jinguang Red pigment easily absorbs moisture, causing pigment particles to agglomerate, making the pigment unstable during long-term storage. Furthermore, due to its needle-shaped particle morphology, the pigment is prone to flocculation, precipitation, or aggregation, resulting in poor dispersion stability, which ultimately affects the pigment's uniformity and gloss. Jinguang Red pigment has poor tolerance to solvents and is prone to migration, making it prone to dissolution or discoloration in solvent environments, which also affects the product's service life and performance. Therefore, modifying Jinguang Red pigment to overcome these shortcomings is of great significance for improving the pigment's performance and expanding its application range in different fields. Summary of the Invention

[0004] In order to solve the above problems, the purpose of the present invention is to provide a method for preparing an organic pigment for coatings based on Jinguanghong.

[0005] To achieve the above-mentioned purpose, the present invention is implemented through the following technical solutions:

[0006] A method for preparing an organic pigment for coatings based on golden red comprises: first, 2-amino-5-chloro-4-methylbenzenesulfonic acid is diazotized, then coupled with a terminal olefin-modified silica-naphthol derivative, then laked with a barium chloride aqueous solution to obtain a terminal olefin-modified golden red pigment, and finally reacting with polyvinyl acetate to prepare the pigment;

[0007] The terminal olefin-modified silica-naphthol derivative is prepared according to the following steps:

[0008] 1) Add nano-silica to a mixture of concentrated sulfuric acid and hydrogen peroxide at a volume ratio of 1:2, soak for 24-48 hours, filter, wash the resulting filter cake with deionized water 2-3 times, and then dry under nitrogen to obtain surface hydroxylated nano-silica;

[0009] 2) Add 2-hydroxy-6-naphthoic acid and tert-butyldimethylsilyl chloride to an organic solvent, then add imidazole, stir to dissolve, and react at 25-30°C for 10-20 hours. After the reaction is complete, remove the solvent by distillation under reduced pressure, add water, and extract with dichloromethane 2-3 times. The obtained organic phase is distilled under reduced pressure to remove the solvent to obtain a hydroxy-protected naphthoic acid derivative;

[0010] 3) adding the surface hydroxylated nano-silica obtained in step 1) to an organic solvent, and then adding the hydroxy-protected naphthoic acid derivative prepared in step 2), acrylic acid, 4-dimethylaminopyridine, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide thereto, reacting at 30-50° C. for 10-24 hours. After the reaction is completed, filtering is performed, and the filter cake is washed 2-3 times with acetone, added to tetrahydrofuran, stirred and mixed, and then tetra-n-butylammonium fluoride is added. The mixture is stirred and reacted at 25-30° C. for 5-10 hours. After the reaction is completed, the solvent is removed by distillation under reduced pressure, and the residue is extracted with dichloromethane and water. Finally, the solvent is removed by distillation under reduced pressure from the obtained organic phase to obtain a terminal olefin-modified silica-naphthol derivative.

[0011] The mass ratio of the nano-silica to the concentrated sulfuric acid-hydrogen peroxide mixture in step 1) is 1:5-10.

[0012] The organic solvent in step 2) is dichloromethane or tetrahydrofuran.

[0013] The mass ratio of 2-hydroxy-6-naphthoic acid, tert-butyldimethylsilyl chloride, organic solvent, imidazole, water and dichloromethane in step 2) is 1:0.8-1.2:5-10:0.4-0.6:8-15:8-15.

[0014] The mass ratio of the surface hydroxylated nano-silica, organic solvent, hydroxyl-protected naphthoic acid derivative, acrylic acid, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, tetrahydrofuran, tetra-n-butylammonium fluoride, dichloromethane and water in step 3) is 1:30-60:8-15:1-3:5-12:8-19:20-40:6.5-13:20-40:20-40.

[0015] The method for preparing the organic pigment for coating based on golden red comprises the following steps:

[0016] ① Add 2-amino-5-chloro-4-methylbenzenesulfonic acid, water and 30% hydrochloric acid to a diazotization reactor, stir and dissolve, cool to 0-10°C, then add 30% sodium nitrite aqueous solution, and diazotize for 2-4 hours to obtain a diazo solution;

[0017] ② Add the terminal olefin-modified silica-naphthol derivative to ethanol, stir and mix evenly, add it to the coupling reactor, and then dropwise add the diazo solution prepared in step ① thereto, and couple it at 25-30°C for 1-2h. After the coupling reaction is completed, adjust the pH of the system to 7.5-8 with a 15-20% mass concentration of sodium hydroxide aqueous solution, stir and react for 20-30min, then adjust the pH of the system to 1-1.5 with hydrochloric acid, stir and react for 20-30min, add a 30% mass concentration of barium chloride aqueous solution, stir for 20-30min, heat to 80-90°C for 1.5-2h, cool to 25-30°C, filter, wash the filter cake with water 3-5 times, and dry to obtain a terminal olefin-modified golden red pigment;

[0018] ③ Add the terminal olefin-modified golden red pigment prepared in step ② and polyvinyl acetate to ethyl acetate, stir and disperse evenly, then add azobisisobutyronitrile, heat to 60-80°C and react for 5-10 hours. After the reaction is completed, remove the solvent by reduced pressure distillation to obtain an organic pigment for coatings based on golden red.

[0019] The mass ratio of 2-amino-5-chloro-4-methylbenzenesulfonic acid, water, hydrochloric acid and sodium nitrite aqueous solution in step ① is 1:4.5~6:1~1.5:1.5~2.

[0020] The mass ratio of the terminal olefin-modified silica-naphthol derivative, ethanol and barium chloride aqueous solution in step ② to the 2-amino-5-chloro-4-methylbenzenesulfonic acid in step ① is 0.5-0.7:5-8:2.4-3:1.

[0021] The mass ratio of the terminal olefin-modified golden red pigment, polyvinyl acetate, ethyl acetate and azobisisobutyronitrile in step ③ is 1:0.4~0.8:10~15:0.002~0.02.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] The organic pigment for coating based on golden red of the present invention is prepared by preparing a terminal olefin-modified silica-naphthol derivative, fixing the pigment on a silica skeleton, and then reacting with polyvinyl acetate to coat a polymer shell layer on the outer layer of the composite pigment through chemical bonds, thereby preparing an organic-inorganic hybrid core-shell structure pigment. The steric hindrance effect of the polymer shell layer prevents close contact and aggregation between pigment particles, thereby improving the dispersion stability of the pigment. The organic-inorganic hybrid core-shell structure prevents water molecules in the environment from penetrating into the interior of the pigment, thereby improving the moisture resistance of the pigment and increasing the long-term storage stability of the pigment.

[0024] The organic pigment for coatings based on golden red of the present invention fixes the pigment on a silica skeleton, and then coats the outer layer of the composite pigment with a polymer shell via chemical bonds, thereby improving the migration resistance of the pigment. On the other hand, polyvinyl acetate reacts with vinyl groups on the surface of silica to form a cross-linked network, and the pigment is connected to the cross-linked polymer and silica via chemical bonds, thereby reducing the solubility of the pigment in solvents and improving its solvent resistance.

[0025] The organic pigment for coatings based on golden red of the present invention uses silicon dioxide as a rigid core, chemically bonds the pigment to its surface, and finally grafts a polymer shell layer through chemical bonds to prepare an organic-inorganic hybrid core-shell structure pigment, which significantly improves the dispersion stability, moisture resistance, migration resistance and solvent resistance of the pigment and enhances its application performance in coatings. DETAILED DESCRIPTION

[0026] In order to better understand the technical solutions of the present invention, the following is a further detailed description of the above content of the present invention through specific implementation methods in the form of examples. However, this should not be construed as limiting the scope of the above subject matter of the present invention to the following examples. All technologies implemented based on the above content of the present invention fall within the scope of the present invention.

[0027] Example 1 Preparation of terminal olefin modified silica-naphthol derivatives:

[0028] 1) Add 1 kg of nano-silica to 5 kg of a 1:2 volume ratio of concentrated sulfuric acid-hydrogen peroxide mixture, soak for 24 hours, and filter. The resulting filter cake is washed twice with deionized water and then dried under nitrogen to obtain surface hydroxylated nano-silica.

[0029] 2) 1 kg of 2-hydroxy-6-naphthoic acid and 0.8 kg of tert-butyldimethylsilyl chloride were added to 5 kg of dichloromethane, followed by 0.4 kg of imidazole. After stirring and dissolving, the mixture was reacted at 25°C for 10 hours. After the reaction, the solvent was removed by distillation under reduced pressure, 8 kg of water was added, and then 8 kg of dichloromethane was added for extraction twice. The organic phase was distilled under reduced pressure to remove the solvent, thereby obtaining a hydroxy-protected naphthoic acid derivative.

[0030] 3) 1 kg of surface hydroxylated nano-silica was added to 30 kg of dichloromethane, and then 8 kg of hydroxy-protected naphthoic acid derivatives, 1 kg of acrylic acid, 5 kg of 4-dimethylaminopyridine and 8 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide were added thereto. The mixture was reacted at 30°C for 24 hours. After the reaction was completed, the mixture was filtered off with suction. The filter cake was washed twice with acetone and added to 20 kg of tetrahydrofuran. After stirring and mixing, 6.5 kg of tetra-n-butylammonium fluoride was added. The mixture was stirred and reacted at 25°C for 10 hours. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The residue was extracted with 20 kg of dichloromethane and 20 kg of water. Finally, the solvent was removed from the organic phase by distillation under reduced pressure to obtain a terminal olefin-modified silica-naphthol derivative.

[0031] Preparation of organic pigments for coatings based on golden red:

[0032] ① Add 1 kg of 2-amino-5-chloro-4-methylbenzenesulfonic acid, 4.5 kg of water, and 1 kg of 30% hydrochloric acid into a diazotization reactor, stir and dissolve, cool to 0°C, and then add 1.5 kg of 30% sodium nitrite aqueous solution. Diazotization reaction is carried out for 2 hours to obtain a diazo solution.

[0033] ② Add 0.5 kg of terminal olefin-modified silica-naphthol derivative to 5 kg of ethanol, stir and mix evenly, add it to the coupling reactor, and then add the diazo solution prepared in step ① dropwise thereto, and couple at 25 ° C for 1 hour. After the coupling reaction is completed, adjust the pH of the system to 7.5 with a 15% mass concentration of sodium hydroxide aqueous solution, stir and react for 20 minutes, then adjust the pH of the system to 1 with hydrochloric acid, stir and react for 20 minutes, add 2.4 kg of a 30% mass concentration of barium chloride aqueous solution, stir for 20 minutes, heat to 80 ° C for 1.5 hours, cool to 25 ° C, filter, wash the filter cake with water 3 times, and dry to obtain a terminal olefin-modified golden red pigment;

[0034] ③ Add 1 kg of the terminal olefin-modified golden red pigment prepared in step ② and 0.4 kg of polyvinyl acetate to 10 kg of ethyl acetate, stir and disperse evenly, then add 0.002 kg of azobisisobutyronitrile, heat to 60 ° C and react for 5 hours. After the reaction is completed, remove the solvent by reduced pressure distillation to obtain an organic pigment for coating based on golden red.

[0035] Example 2 Preparation of terminal olefin modified silica-naphthol derivatives:

[0036] 1) 1 kg of nano-silica was added to 6 kg of a 1:2 volume ratio of concentrated sulfuric acid-hydrogen peroxide mixture, soaked for 30 hours, and then filtered. The resulting filter cake was washed three times with deionized water and then dried under nitrogen to obtain surface hydroxylated nano-silica.

[0037] 2) 1 kg of 2-hydroxy-6-naphthoic acid and 0.9 kg of tert-butyldimethylsilyl chloride were added to 6 kg of dichloromethane, followed by 0.45 kg of imidazole. After stirring and dissolving, the mixture was reacted at 26°C for 12 hours. After the reaction, the solvent was removed by distillation under reduced pressure, 10 kg of water was added, and then 11 kg of dichloromethane was added for extraction three times. The resulting organic phase was distilled under reduced pressure to remove the solvent, thereby obtaining a hydroxy-protected naphthoic acid derivative.

[0038] 3) 1 kg of surface hydroxylated nano-silica was added to 35 kg of tetrahydrofuran, and then 9 kg of hydroxy-protected naphthoic acid derivatives, 1.5 kg of acrylic acid, 6.5 kg of 4-dimethylaminopyridine and 10 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide were added thereto. The mixture was reacted at 35°C for 20 hours. After the reaction was completed, the mixture was filtered off with suction. The filter cake was washed three times with acetone and added to 25 kg of tetrahydrofuran. After stirring and mixing, 7.5 kg of tetra-n-butylammonium fluoride was added. The mixture was stirred and reacted at 26°C for 8 hours. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The residue was extracted with 25 kg of dichloromethane and 25 kg of water. Finally, the solvent was removed from the organic phase by distillation under reduced pressure to obtain terminal olefin-modified silica-naphthol derivatives.

[0039] Preparation of organic pigments for coatings based on golden red:

[0040] ① Add 1 kg of 2-amino-5-chloro-4-methylbenzenesulfonic acid, 5 kg of water, and 1.1 kg of 30% hydrochloric acid to a diazotization reactor, stir and dissolve, cool to 5°C, and then add 1.6 kg of 30% sodium nitrite aqueous solution. Diazotization reaction is carried out for 2.5 hours to obtain a diazo solution.

[0041] ② Add 0.55 kg of terminal olefin-modified silica-naphthol derivative to 5.5 kg of ethanol, stir and mix evenly, add it to the coupling reactor, and then add the diazo solution prepared in step ① dropwise thereto, and couple it at 27 ° C for 1.5 hours. After the coupling reaction is completed, adjust the pH of the system to 8 with a 15% mass concentration of sodium hydroxide aqueous solution, stir and react for 25 minutes, then adjust the pH of the system to 1.5 with hydrochloric acid, stir and react for 25 minutes, add 2.6 kg of a 30% mass concentration of barium chloride aqueous solution, stir for 25 minutes, heat to 85 ° C for 1.6 hours, cool to 26 ° C, filter, wash the filter cake with water 5 times, and dry to obtain a terminal olefin-modified golden red pigment;

[0042] ③ Add 1 kg of the terminal olefin-modified golden red pigment prepared in step ② and 0.5 kg of polyvinyl acetate to 11 kg of ethyl acetate, stir and disperse evenly, then add 0.005 kg of azobisisobutyronitrile, heat to 65 ° C and react for 9 hours. After the reaction is completed, remove the solvent by reduced pressure distillation to obtain an organic pigment for coating based on golden red.

[0043] Example 3 Preparation of terminal olefin modified silica-naphthol derivatives:

[0044] 1) Add 1 kg of nano-silica to 8 kg of a 1:2 volume ratio of concentrated sulfuric acid-hydrogen peroxide mixture, soak for 35 hours, and filter. The resulting filter cake is washed three times with deionized water and then dried under nitrogen to obtain surface hydroxylated nano-silica.

[0045] 2) 1 kg of 2-hydroxy-6-naphthoic acid and 1 kg of tert-butyldimethylsilyl chloride were added to 7.5 kg of tetrahydrofuran, followed by 0.5 kg of imidazole. After stirring and dissolving, the mixture was reacted at 28°C for 15 hours. After the reaction, the solvent was removed by distillation under reduced pressure, 11 kg of water was added, and then 13 kg of dichloromethane was added and extracted three times. The organic phase was distilled under reduced pressure to remove the solvent, thereby obtaining a hydroxy-protected naphthoic acid derivative.

[0046] 3) 1 kg of surface hydroxylated nano-silica was added to 45 kg of dichloromethane, and then 12 kg of hydroxy-protected naphthoic acid derivatives, 2.2 kg of acrylic acid, 8 kg of 4-dimethylaminopyridine and 14 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide were added thereto. The mixture was reacted at 40°C for 18 hours. After the reaction was completed, the mixture was filtered off with suction. The filter cake was washed three times with acetone and added to 30 kg of tetrahydrofuran. After stirring and mixing, 9.5 kg of tetra-n-butylammonium fluoride was added. The mixture was stirred and reacted at 28°C for 7 hours. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The residue was extracted with 30 kg of dichloromethane and 30 kg of water. Finally, the solvent was removed from the organic phase by distillation under reduced pressure to obtain terminal olefin-modified silica-naphthol derivatives.

[0047] Preparation of organic pigments for coatings based on golden red:

[0048] ① Add 1 kg of 2-amino-5-chloro-4-methylbenzenesulfonic acid, 5.5 kg of water, and 1.3 kg of 30% hydrochloric acid into a diazotization reactor, stir and dissolve, cool to 8°C, and then add 1.8 kg of 30% sodium nitrite aqueous solution. Diazotization reaction is carried out for 2.5 hours to obtain a diazo solution.

[0049] ② Add 0.62 kg of terminal olefin-modified silica-naphthol derivative to 6.5 kg of ethanol, stir and mix evenly, add it to the coupling reactor, and then add the diazo solution prepared in step ① dropwise thereto, and couple it at 28 ° C for 1.8 hours. After the coupling reaction is completed, adjust the pH of the system to 7.5 with a 15% mass concentration of sodium hydroxide aqueous solution, stir and react for 25 minutes, then adjust the pH of the system to 1.5 with hydrochloric acid, stir and react for 25 minutes, add 2.8 kg of a 30% mass concentration of barium chloride aqueous solution, stir for 25 minutes, heat to 85 ° C for 1.8 hours, cool to 28 ° C, filter, wash the filter cake with water 5 times, and dry to obtain a terminal olefin-modified golden red pigment;

[0050] ③ Add 1 kg of the terminal olefin-modified golden red pigment prepared in step ② and 0.6 kg of polyvinyl acetate to 13 kg of ethyl acetate, stir and disperse evenly, then add 0.01 kg of azobisisobutyronitrile, heat to 70 ° C and react for 8 hours. After the reaction is completed, remove the solvent by reduced pressure distillation to obtain an organic pigment for coating based on golden red.

[0051] Example 4 Preparation of terminal olefin modified silica-naphthol derivatives:

[0052] 1) 1 kg of nano-silica was added to 9 kg of a 1:2 volume ratio of concentrated sulfuric acid-hydrogen peroxide mixture, soaked for 40 hours, and then filtered. The resulting filter cake was washed three times with deionized water and then dried under nitrogen to obtain surface hydroxylated nano-silica.

[0053] 2) 1 kg of 2-hydroxy-6-naphthoic acid and 1.1 kg of tert-butyldimethylsilyl chloride were added to 8.5 kg of tetrahydrofuran, followed by 0.52 kg of imidazole. After stirring and dissolving, the mixture was reacted at 29°C for 17 hours. After the reaction, the solvent was removed by distillation under reduced pressure, 12 kg of water was added, and then 13 kg of dichloromethane was added and extracted three times. The resulting organic phase was distilled under reduced pressure to remove the solvent, thereby obtaining a hydroxy-protected naphthoic acid derivative.

[0054] 3) 1 kg of surface hydroxylated nano-silica was added to 50 kg of tetrahydrofuran, and then 13 kg of hydroxy-protected naphthoic acid derivatives, 2.5 kg of acrylic acid, 10 kg of 4-dimethylaminopyridine and 16 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide were added thereto. The mixture was reacted at 40°C for 15 hours. After the reaction was completed, the mixture was filtered off with suction. The filter cake was washed three times with acetone and added to 33 kg of tetrahydrofuran. After stirring and mixing, 10 kg of tetra-n-butylammonium fluoride was added. The mixture was stirred and reacted at 26°C for 8 hours. After the reaction was completed, the solvent was removed by distillation under reduced pressure. The residue was extracted with 32 kg of dichloromethane and 35 kg of water. Finally, the solvent was removed from the organic phase by distillation under reduced pressure to obtain a terminal olefin-modified silica-naphthol derivative.

[0055] Preparation of organic pigments for coatings based on golden red:

[0056] ① Add 1 kg of 2-amino-5-chloro-4-methylbenzenesulfonic acid, 5.6 kg of water, and 1.4 kg of 30% hydrochloric acid into a diazotization reactor, stir and dissolve, cool to 5°C, and then add 1.7 kg of 30% sodium nitrite aqueous solution. Diazotization reaction is carried out for 2.5 hours to obtain a diazo solution.

[0057] ② Add 0.65 kg of terminal olefin-modified silica-naphthol derivative to 7 kg of ethanol, stir and mix evenly, add it to the coupling reactor, and then add the diazo solution prepared in step ① dropwise thereto, and couple it at 29 ° C for 1.8 hours. After the coupling reaction is completed, adjust the pH of the system to 8 with a 15% mass concentration of sodium hydroxide aqueous solution, stir and react for 28 minutes, then adjust the pH of the system to 1 with hydrochloric acid, stir and react for 25 minutes, add 2.8 kg of a 30% mass concentration of barium chloride aqueous solution, stir for 30 minutes, heat to 85 ° C for 1.5 hours, cool to 28 ° C, filter, wash the filter cake with water 4 times, and dry to obtain a terminal olefin-modified golden red pigment;

[0058] ③ Add 1 kg of the terminal olefin-modified golden red pigment prepared in step ② and 0.7 kg of polyvinyl acetate to 14 kg of ethyl acetate, stir and disperse evenly, then add 0.012 kg of azobisisobutyronitrile, heat to 75 ° C and react for 6 hours. After the reaction is completed, remove the solvent by reduced pressure distillation to obtain an organic pigment for coating based on golden red.

[0059] Example 5 Preparation of terminal olefin modified silica-naphthol derivatives:

[0060] 1) 1 kg of nano-silica was added to 10 kg of a mixture of concentrated sulfuric acid and hydrogen peroxide at a volume ratio of 1:2, and the mixture was soaked for 45 hours. The mixture was then filtered, and the resulting filter cake was washed three times with deionized water and dried under nitrogen to obtain surface hydroxylated nano-silica.

[0061] 2) 1 kg of 2-hydroxy-6-naphthoic acid and 1.2 kg of tert-butyldimethylsilyl chloride were added to 9 kg of dichloromethane, followed by 0.55 kg of imidazole. After stirring and dissolving, the mixture was reacted at 30°C for 20 hours. After the reaction, the solvent was removed by distillation under reduced pressure, 13 kg of water was added, and then 15 kg of dichloromethane was added for extraction three times. The obtained organic phase was distilled under reduced pressure to remove the solvent, thereby obtaining a hydroxy-protected naphthoic acid derivative.

[0062] 3) 1 kg of surface hydroxylated nano-silica was added to 55 kg of tetrahydrofuran, and then 14 kg of hydroxy-protected naphthoic acid derivatives, 2.8 kg of acrylic acid, 11 kg of 4-dimethylaminopyridine and 18 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide were added thereto, and the mixture was reacted at 45°C for 13 hours. After the reaction was completed, the mixture was filtered, and the filter cake was washed three times with acetone, added to 36 kg of tetrahydrofuran, stirred and mixed, and then 12 kg of tetra-n-butylammonium fluoride was added. The mixture was stirred and reacted at 28°C for 6 hours. After the reaction was completed, the solvent was removed by distillation under reduced pressure, and the residue was extracted with 35 kg of dichloromethane and 38 kg of water. Finally, the solvent was removed from the obtained organic phase by distillation under reduced pressure to obtain a terminal olefin-modified silica-naphthol derivative.

[0063] Preparation of organic pigments for coatings based on golden red:

[0064] ① Add 1 kg of 2-amino-5-chloro-4-methylbenzenesulfonic acid, 5.8 kg of water, and 1.4 kg of 30% hydrochloric acid into a diazotization reactor, stir and dissolve, cool to 10°C, and then add 1.8 kg of 30% sodium nitrite aqueous solution. Diazotization reaction is carried out for 3.5 hours to obtain a diazo solution.

[0065] ② Add 0.68 kg of terminal olefin-modified silica-naphthol derivative to 7.5 kg of ethanol, stir and mix evenly, add it to the coupling reactor, and then add the diazo solution prepared in step ① dropwise thereto, and couple at 30 ° C for 2 hours. After the coupling reaction is completed, adjust the pH of the system to 7.8 with a 15% mass concentration of sodium hydroxide aqueous solution, stir and react for 30 minutes, then adjust the pH of the system to 1.2 with hydrochloric acid, stir and react for 30 minutes, add 2.9 kg of a 30% mass concentration of barium chloride aqueous solution, stir for 30 minutes, heat to 88 ° C for 1.5 hours, cool to 30 ° C, filter, wash the filter cake with water 5 times, and dry to obtain a terminal olefin-modified golden red pigment;

[0066] ③ Add 1 kg of the terminal olefin-modified golden red pigment prepared in step ② and 0.75 kg of polyvinyl acetate to 14 kg of ethyl acetate, stir and disperse evenly, then add 0.015 kg of azobisisobutyronitrile, heat to 78 ° C and react for 6 hours. After the reaction is completed, remove the solvent by reduced pressure distillation to obtain an organic pigment for coating based on golden red.

[0067] Example 6 Preparation of terminal olefin modified silica-naphthol derivatives:

[0068] 1) 1 kg of nano-silica was added to 10 kg of a mixture of concentrated sulfuric acid and hydrogen peroxide at a volume ratio of 1:2, and the mixture was soaked for 48 hours. The mixture was then filtered, and the resulting filter cake was washed three times with deionized water and dried under nitrogen to obtain surface hydroxylated nano-silica.

[0069] 2) Add 1 kg of 2-hydroxy-6-naphthoic acid and 1 kg of tert-butyldimethylsilyl chloride to 10 kg of dichloromethane, then add 0.6 kg of imidazole, stir to dissolve, and react at 30°C for 10 hours. After the reaction is complete, remove the solvent by distillation under reduced pressure, add 15 kg of water, and then extract three times with 15 kg of dichloromethane. The obtained organic phase is distilled under reduced pressure to remove the solvent to obtain a hydroxy-protected naphthoic acid derivative;

[0070] 3) 1 kg of surface hydroxylated nano-silica was added to 60 kg of tetrahydrofuran, and then 15 kg of hydroxy-protected naphthoic acid derivatives, 3 kg of acrylic acid, 12 kg of 4-dimethylaminopyridine and 19 kg of 1-ethyl-(3-dimethylaminopropyl)carbodiimide were added thereto, and the mixture was reacted at 50°C for 10 hours. After the reaction was completed, the mixture was filtered, and the filter cake was washed three times with acetone, added to 40 kg of tetrahydrofuran, stirred and mixed, and then 13 kg of tetra-n-butylammonium fluoride was added. The mixture was stirred and reacted at 30°C for 5 hours. After the reaction was completed, the solvent was removed by distillation under reduced pressure, and the residue was extracted with 40 kg of dichloromethane and 40 kg of water. Finally, the solvent was removed from the obtained organic phase by distillation under reduced pressure to obtain terminal olefin-modified silica-naphthol derivatives.

[0071] Preparation of organic pigments for coatings based on golden red:

[0072] ① Add 1 kg of 2-amino-5-chloro-4-methylbenzenesulfonic acid, 6 kg of water, and 1.5 kg of 30% hydrochloric acid into a diazotization reactor, stir and dissolve, cool to 10°C, and then add 2 kg of 30% sodium nitrite aqueous solution. Diazotization reaction is carried out for 4 hours to obtain a diazo solution.

[0073] ② Add 0.7 kg of terminal olefin-modified silica-naphthol derivative to 8 kg of ethanol, stir and mix evenly, add it to the coupling reactor, and then add the diazo solution prepared in step ① dropwise thereto, and couple at 30 ° C for 1 hour. After the coupling reaction is completed, adjust the pH of the system to 8 with a 15% mass concentration of sodium hydroxide aqueous solution, stir and react for 25 minutes, then adjust the pH of the system to 1 with hydrochloric acid, stir and react for 30 minutes, add 3 kg of a 30% mass concentration of barium chloride aqueous solution, stir for 30 minutes, heat to 90 ° C for 2 hours, cool to 30 ° C, filter, wash the filter cake with water 5 times, and dry to obtain a terminal olefin-modified golden red pigment;

[0074] ③ Add 1 kg of the terminal olefin-modified golden red pigment prepared in step ② and 0.8 kg of polyvinyl acetate to 15 kg of ethyl acetate, stir and disperse evenly, then add 0.02 kg of azobisisobutyronitrile, heat to 80 ° C and react for 10 hours. After the reaction is completed, remove the solvent by reduced pressure distillation to obtain an organic pigment for coating based on golden red.

[0075] The Jinguanghong-based organic pigments for coatings prepared in Examples 1 to 6 were subjected to performance tests. Lightfastness was tested according to the method specified in GB1710-79; water resistance, acid and alkali resistance were tested according to the method specified in GB 5211.5-2008-T; oil absorption was tested according to the method specified in GB / T 5211.15-2014; heat resistance was tested according to the method specified in HG / T 3853-2006; and solvent resistance was tested according to the method specified in GB / T 23989-2009 (Method A, ethanol wiping). A comparative example, Jinguanghong C (PR53:1) for coatings produced by our company, was used. The test results are shown in Table 1. As can be seen from the results in Table 1, the Jinguanghong-based organic pigments for coatings prepared by the present invention exhibit strong lightfastness, water resistance, acid and alkali resistance, heat resistance, and solvent resistance.

[0076] Table 1 Performance test results of pigments prepared in Examples 1 to 6

[0077]

[0078] In parts by weight, the organic pigments for coatings based on golden red prepared in Examples 1 to 6 and 1 part of the comparative pigment, 4 parts of alkyd resin and 5 parts of xylene were mixed evenly, stirred at 2000 r / min for 30 minutes, and the obtained color paste was coated on a glass plate. After drying, a pigment test plate was obtained, which was covered on a white substrate (pigment side facing down) and heated at 1 kg / cm 2 After being placed in close contact at 80°C for 24 hours, the degree of contamination of the white substrate was observed and evaluated using a standard gray scale, with grade 5 indicating no migration and grade 1 indicating severe migration. The test results are shown in Table 2. As can be seen from the results in Table 2, the organic pigment for coatings based on Jinguang Red prepared in the present invention has higher migration resistance than that of the comparative example.

[0079] Table 2 Migration resistance results of the pigments obtained in Examples 1 to 6

[0080]

[0081] Although the above describes the specific implementation methods of the present invention, it does not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A method for preparing an organic pigment for coatings based on golden red, characterized in that: 2-amino-5-chloro-4-methylbenzenesulfonic acid is first diazotized and then coupled with a terminal olefin-modified silica-naphthol derivative. A barium chloride aqueous solution is then added for lake formation to obtain a terminal olefin-modified golden red pigment. The prepared terminal olefin-modified golden red pigment and polyvinyl acetate are added to ethyl acetate and stirred for uniform dispersion. Azobisisobutyronitrile is then added and the mixture is heated to 60-80°C for reaction for 5-10 hours. After the reaction is complete, the solvent is removed by reduced pressure distillation to obtain an organic pigment for coatings based on golden red. The terminal olefin-modified silica-naphthol derivative is prepared according to the following steps: 1) Add nano-silica to a mixture of concentrated sulfuric acid and hydrogen peroxide at a volume ratio of 1:2, soak for 24-48 hours, filter, wash the resulting filter cake with deionized water 2-3 times, and then dry under nitrogen to obtain surface hydroxylated nano-silica; 2) Add 2-hydroxy-6-naphthoic acid and tert-butyldimethylsilyl chloride to an organic solvent, then add imidazole, stir to dissolve, and react at 25-30°C for 10-20 hours. After the reaction is complete, remove the solvent by distillation under reduced pressure, add water, and extract with dichloromethane 2-3 times. The obtained organic phase is distilled under reduced pressure to remove the solvent to obtain a hydroxy-protected naphthoic acid derivative; 3) adding the surface hydroxylated nano-silica obtained in step 1) to an organic solvent, and then adding the hydroxy-protected naphthoic acid derivative prepared in step 2), acrylic acid, 4-dimethylaminopyridine, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide thereto, reacting at 30-50° C. for 10-24 hours. After the reaction is completed, filtering is performed, and the filter cake is washed 2-3 times with acetone, added to tetrahydrofuran, stirred and mixed, and then tetra-n-butylammonium fluoride is added. The mixture is stirred and reacted at 25-30° C. for 5-10 hours. After the reaction is completed, the solvent is removed by distillation under reduced pressure, and the residue is extracted with dichloromethane and water. Finally, the solvent is removed by distillation under reduced pressure from the obtained organic phase to obtain a terminal olefin-modified silica-naphthol derivative.

2. The method for preparing an organic pigment for coatings based on Jinguanghong according to claim 1, wherein: The mass ratio of the nano-silica to the concentrated sulfuric acid-hydrogen peroxide mixture in step 1) is 1:5-10.

3. The method for preparing an organic pigment for coatings based on Jinguanghong according to claim 1, wherein: The organic solvent in step 2) is dichloromethane or tetrahydrofuran.

4. The method for preparing an organic pigment for coatings based on Jinguanghong according to claim 1, wherein: The mass ratio of 2-hydroxy-6-naphthoic acid, tert-butyldimethylsilyl chloride, organic solvent, imidazole, water and dichloromethane in step 2) is 1:0.8-1.2:5-10:0.4-0.6:8-15:8-15.

5. The method for preparing an organic pigment for coatings based on Jinguanghong according to claim 1, wherein: The mass ratio of the surface hydroxylated nano-silica, organic solvent, hydroxyl-protected naphthoic acid derivative, acrylic acid, 4-dimethylaminopyridine, 1-ethyl-(3-dimethylaminopropyl)carbodiimide, tetrahydrofuran, tetra-n-butylammonium fluoride, dichloromethane and water in step 3) is 1:30-60:8-15:1-3:5-12:8-19:20-40:6.5-13:20-40:20-40.

6. The method for preparing an organic pigment for coatings based on Jinguanghong according to claim 1, wherein: The following steps are involved: ① Add 2-amino-5-chloro-4-methylbenzenesulfonic acid, water and 30% hydrochloric acid to a diazotization reactor, stir and dissolve, cool to 0-10°C, then add 30% sodium nitrite aqueous solution and diazotize for 2-4 hours to obtain a diazo solution; ② Add the terminal olefin-modified silica-naphthol derivative to ethanol, stir and mix evenly, add it to the coupling reactor, and then dropwise add the diazo solution prepared in step ① thereto, and couple it at 25-30°C for 1-2h. After the coupling reaction is completed, adjust the pH of the system to 7.5-8 with a 15-20% mass concentration of sodium hydroxide aqueous solution, stir and react for 20-30min, then adjust the pH of the system to 1-1.5 with hydrochloric acid, stir and react for 20-30min, add a 30% mass concentration of barium chloride aqueous solution, stir for 20-30min, heat to 80-90°C for 1.5-2h, cool to 25-30°C, filter, wash the filter cake with water 3-5 times, and dry to obtain a terminal olefin-modified golden red pigment; ③ Add the terminal olefin-modified golden red pigment prepared in step ② and polyvinyl acetate to ethyl acetate, stir and disperse evenly, then add azobisisobutyronitrile, heat to 60-80°C and react for 5-10 hours. After the reaction is completed, remove the solvent by reduced pressure distillation to obtain an organic pigment for coatings based on golden red.

7. The method for preparing an organic pigment for coatings based on Jinguanghong according to claim 6, characterized in that: The mass ratio of 2-amino-5-chloro-4-methylbenzenesulfonic acid, water, hydrochloric acid and sodium nitrite aqueous solution in step ① is 1:4.5~6:1~1.5:1.5~2.

8. The method for preparing an organic pigment for coatings based on Jinguanghong according to claim 6, wherein: The mass ratio of the terminal olefin-modified silica-naphthol derivative, ethanol and barium chloride aqueous solution in step ② to the 2-amino-5-chloro-4-methylbenzenesulfonic acid in step ① is 0.5-0.7:5-8:2.4-3:

1.

9. The method for preparing an organic pigment for coatings based on Jinguanghong according to claim 6, wherein: The mass ratio of the terminal olefin-modified golden red pigment, polyvinyl acetate, ethyl acetate and azobisisobutyronitrile in step ③ is 1:0.4~0.8:10~15:0.002~0.02.

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