A method for modifying a dpp-based pigment with a tertiary butanol alkali metal salt

Abstract

The application provides a method for modifying DPP pigment with a tertiary butyl alcohol alkali salt, which uses DPP pigment as raw material, and also uses a tertiary butyl alcohol alkali salt, carbon dioxide and sulfonyl chloride as raw material; and uses an aprotic solvent as solvent; the method first synthesizes a salt containing a tert-butyloxycarbonyl group, and then uses the tert-butyloxycarbonyl group in the salt to modify an imino group in a DPP pigment molecule to obtain a modified DPP pigment. The application uses DPP pigment, a tertiary butyl alcohol alkali salt, carbon dioxide and sulfonyl chloride as raw material, uses an aprotic solvent as solvent, uses a unique molecular structure design, synthesizes a tert-butyloxycarbonyl group to directly modify an imino group on a DPP pigment molecule to achieve the purpose of chemical modification; the side reaction is low, and the generated by-product can be removed by water washing, and will not affect the performance of the parent pigment.

Description

Technical Field

[0001] This invention belongs to the field of organic pigment technology, and relates to DPP-based pigments, specifically to a method for modifying DPP-based pigments with tert-butanol alkali metal salt. Background Technology

[0002] DPP-based pigments are a class of high-performance organic pigments. They are non-toxic and harmless, and represent a high-end heterocyclic organic pigment with enormous development potential, poised to replace azo pigments which pose a significant carcinogenic risk and cause substantial pollution during production. The advent of this class of pigments is hailed as a new milestone in the history of organic pigment development. There are many types of DPP-based organic pigments, with DPP 254 and DPP 255 being the most commonly used. These pigments possess excellent coloring properties, vibrant colors, and high tinting strength, and are widely used in the formulation of industrial paints and inks, exhibiting high commercial value and development potential.

[0003] However, DPP-type organic pigments are insoluble in water and most organic solvents. Furthermore, due to their high surface energy, pigment particles tend to flocculate and aggregate into larger particles under the influence of intermolecular forces and gravity, affecting the dispersion effect. Therefore, surface treatment of the pigments is necessary. Traditional dispersion methods include grinding or surface treatment of the pigments, and the addition of additives such as organic amines, rosin, surfactants, or molecular dispersants to the pigment dispersion system.

[0004] Ciba et al. proposed a "hidden pigment method," which provides a new approach to the chemical modification of DPP-type pigments. The essence of hidden pigment technology is the preparation of a soluble pigment matrix that is readily soluble or dispersed in the application medium. Through heating, chemical, or photochemical reactions, it is reconstituted back into the pigment matrix. This method primarily involves introducing a large protecting group at a specific position within the molecule, temporarily disrupting intermolecular and intramolecular hydrogen bonds. This makes the pigment soluble while simultaneously making the derivative unstable to thermal, chemical, or photochemical reactions, and the protecting group is easily eliminated.

[0005] Existing technologies disclose the conversion of DPP pigments into soluble derivatives by treating them with di-tert-butyl dicarbonate under N,N-dimethylaminopyridine catalysis. While this method achieves higher solubility in organic solvents compared to the original parent pigment, the conversion rate of DPP pigments is low. Furthermore, di-tert-butyl dicarbonate readily loses a carbon dioxide ion during modification, transforming into tert-butyl dicarbonate, leading to side reactions and contamination of the DPP pigments. Therefore, a more stable chemical method is needed to modify DPP-based pigments. Summary of the Invention

[0006] In view of the shortcomings of the existing technology, the purpose of this invention is to provide a method for modifying DPP pigments with tert-butanol alkali metal salt, thereby solving the technical problem that in the existing modification methods, while ensuring the dispersibility of DPP pigments, the negative impact of by-reaction products on DPP pigments needs to be further reduced.

[0007] To solve the above-mentioned technical problems, the present invention adopts the following technical solution:

[0008] A method for modifying DPP pigments with tert-butanol alkali metal salts, wherein the method uses DPP pigments as raw materials, and also uses tert-butanol alkali metal salts, carbon dioxide, and sulfonyl chloride as raw materials; and uses an aprotic solvent as a solvent; the method first synthesizes a salt containing tert-butoxycarbonyl, and then uses the tert-butoxycarbonyl in the salt to modify the imino group in the DPP pigment molecule to obtain the modified DPP pigment.

[0009] The present invention also has the following technical features:

[0010] The DPP-based pigment is either DPP-based 254 pigment or DPP-based 255 pigment.

[0011] The alkali metal salt of tert-butanol is sodium tert-butanol or potassium tert-butanol.

[0012] The aprotic solvent is dichloromethane, dichloroethane, carbon tetrachloride, n-hexane, or petroleum ether.

[0013] The method includes the following steps:

[0014] Step 1: Add the aprotic solvent to the reaction vessel, replace it with anhydrous nitrogen three times, add the tert-butanol alkali metal salt, stir evenly, and cool to -10 to 5℃.

[0015] Step 2: Introduce anhydrous carbon dioxide and carry out the reaction at a reaction temperature of -10 to 5°C. Observe the tail gas. Initially, no gas is released. Under these conditions, salts containing tert-butyloxycarbonyl groups will be formed successively. When gas is released, continue to introduce carbon dioxide for another 0.5 hours and then stop introducing gas.

[0016] Step 3: Slowly add DPP-based pigments and stir until a suspension is formed. Then heat the mixture to 0-10°C.

[0017] Step four: Add a sulfonyl chloride solution diluted with an aprotic solvent dropwise, controlling the dropping rate, and complete the addition in 1-2 hours. Then, raise the temperature again to 25℃-35℃ and continue the reaction for 3 hours. During the reaction, under the action of sulfonyl chloride, the salt on the tert-butoxycarbonyl group is removed, and the tert-butoxycarbonyl group directly replaces the hydrogen atom on the imino group on the DPP pigment to achieve the modification of the imino group.

[0018] Step 5: After the reaction is complete, the reaction system is washed with water, dried, and vacuum distilled to obtain the modified DPP pigment.

[0019] In step one, the mass ratio of tert-butanol alkali metal salt to aprotic solvent is 1:(10-20).

[0020] In step three, the molar ratio of DPP pigment to carbon dioxide is 1:(3.0~5.0); the molar ratio of DPP pigment to tert-butanol alkali metal salt is 1:(2.0~3.5); and the reaction temperature is 0~10℃.

[0021] In step three, the purity of the tert-butanol alkali metal salt is >99 wt.%, and the free alkali is <1 wt.%.

[0022] In step four, the molar ratio of DPP pigment to sulfonyl chloride is 1:(1.0~1.75).

[0023] In step four, the amount of aprotic solvent added is 3 to 5 times the mass of sulfonyl chloride.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] (I) This invention uses DPP pigments, tert-butanol alkali metal salts, carbon dioxide, and sulfonyl chloride as raw materials, and aprotic solvents as solvents. It adopts a unique molecular structure design to synthesize tert-butoxycarbonyl groups to directly modify the imino groups on the DPP pigment molecules to achieve the purpose of chemical modification. The side reactions are low, and the generated byproducts can be removed by washing with water without affecting the performance of the parent pigment.

[0026] (II) This invention involves direct modification of a DPP-based parent pigment, resulting in a change in the system's color. The modified DPP pigment is readily soluble or dispersed in a suitable medium. Upon heating to 120–150°C, the system releases carbon dioxide and isobutylene, causing the pigment color to change from yellow-green to the parent pigment's red color, thus reverting to a fine-grained, uniform DPP pigment—essentially restoring it to its initial DPP parent pigment state. This color change, combined with increased solubility and ease of conversion back to the parent pigment, significantly enhances the application range and performance.

[0027] (III) The modification method of the present invention uses batch addition of raw materials and staged heating, which makes the chemical modification process stable and gentle, with high yield and significantly improved solubility of the modified pigment. Attached Figure Description

[0028] Figure 1 The image shows the X-ray diffraction pattern of DPP-based 254 pigment.

[0029] Figure 2 The image shows the X-ray diffraction pattern of DPP-based 255 pigment.

[0030] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0031] It should be noted that, unless otherwise specified, all raw materials used in this invention are those known in the prior art. For example, both DPP-based 254 pigment and DPP-based 255 pigment are commercially available DPP-based 254 pigment or DPP-based 255 pigment.

[0032] This invention provides a method for modifying DPP-based pigments with tert-butanol alkali metal salts. The method uses DPP-based pigments as raw materials, and also uses tert-butanol alkali metal salts, carbon dioxide, and sulfonyl chloride as raw materials; an aprotic solvent is used as the solvent. The method first synthesizes a salt containing a tert-butoxycarbonyl group, and then uses the tert-butoxycarbonyl group in the salt to modify the imino groups in the DPP-based pigment molecules, thus obtaining the modified DPP-based pigment. The overall reaction equation of this invention is as follows:

[0033]

[0034] In the formula: R is -H or -Cl.

[0035] Testing instruments:

[0036] Infrared spectroscopy: The infrared absorption spectrum of the sample was determined using a Spectrum GX Fourier transform infrared spectrometer and the total reflectance method.

[0037] Elemental analysis: Qualitative and quantitative analysis of the modified DPP pigments was performed using an Elementar Vario EL III elemental analyzer.

[0038] Nuclear magnetic resonance analysis: Qualitative analysis of the modified DPP pigments was performed using an AVANCE AV500 nuclear magnetic resonance spectrometer from Bruker GmbH, Germany.

[0039] Solubility comparison: Using commonly used xylene and cyclopentanone as experimental solvents, the solubility before and after modification was compared.

[0040] X-ray diffraction analysis: Qualitative analysis of the modified DPP-based parent pigment was performed using an X-ray diffractometer. The method was as follows: a small amount of the pigment powder was ground finely in a mortar, pressed into a thin sheet in a standard aluminum frame, and measured using a Rigaku (Japan) D / max-2500PC X-ray diffractometer. The measurement conditions were: operating voltage 40 kV, operating current 150 mA, scanning speed 8° / min, and paper feed speed 0.3 m / min.

[0041] The following are specific embodiments of the present invention. It should be noted that the present invention is not limited to the following specific embodiments. All equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0042] Example 1:

[0043] This embodiment provides a method for modifying DPP-based pigments with tert-butanol alkali metal salt, the method comprising the following steps:

[0044] Step 1: Add 200g of dichloromethane to the reactor, purge with anhydrous nitrogen three times, add 20g of sodium tert-butoxide, stir well, and cool to -5℃.

[0045] Step two: Introduce anhydrous carbon dioxide at a rate of 0.1 L / min to initiate the reaction. Observe the tail gas; initially, no gas is released. After 1 hour of aeration, gas release begins. Continue introducing carbon dioxide for another 0.5 hours, then stop aeration.

[0046] Step 3: Slowly add 35g of DPP 254 pigment, stir until it is in a suspension state, heat to 10℃, and at the same time prepare sulfonyl chloride solution (14g sulfonyl chloride plus 50g dichloromethane).

[0047] Step 4: At 10℃, add sulfonyl chloride solution dropwise at a controlled rate. The addition is completed in 1 hour. Then, raise the temperature to 25℃ and continue the reaction for 3 hours.

[0048] Step 5: After washing, drying and vacuum distilling the reaction mixture, 52.43 g of modified DPP-based 254 pigment was obtained, which was brownish-yellow in color, with a yield of 96.01%.

[0049] Structural assessment:

[0050] (1) Elemental analysis of modified DPP-based 254 pigment:

[0051] Molecular formula: C 28 H 26 O6N2Cl2, molecular weight 557.42.

[0052] Theoretical calculations: C 60.33%; H 4.70%; O 17.22%; N 5.02%.

[0053] Actual measured values: C 60.28%; H 4.63%; O 17.18%; N 5.00%.

[0054] The actual measured values ​​are basically consistent with the theoretical calculated values.

[0055] (2) Infrared spectral determination of modified DPP-based 254 pigment:

[0056] IR (iquid film):υ c＝c :1607,1508;υ c＝o :1860,1800,1733,1695;υ as c-o-c :1200,1158;

[0057] υ c-o :1150,1058;υ c-N :1170,1020;δ c-cl 748,700.

[0058] (3) 1H NMR spectrum of modified DPP-based 254 pigment:

[0059] 1 H-NMR(CDCl3): 7.69(d, 4H); 7.46(d, 4H); 1.44(s, 18H)

[0060] As can be seen from the above structural identification results, the brownish-yellow product obtained in this embodiment is the target product modified DPP-based 254 pigment.

[0061] Example 2:

[0062] This embodiment provides a method for modifying DPP-based pigments with tert-butanol alkali metal salt, the method comprising the following steps:

[0063] Step 1: Add 100g of n-hexane to the reactor, purge with anhydrous nitrogen three times, add 20g of potassium tert-butoxide, stir well, and cool to 0℃.

[0064] Step two: Introduce anhydrous carbon dioxide at a rate of 0.1 L / min to initiate the reaction. Observe the tail gas; initially, no gas is released. After 50 minutes of aeration, gas release begins. Continue introducing carbon dioxide for another 0.5 hours, then stop aeration.

[0065] Step 3: Slowly add 30g of DPP 254 pigment, stir until it is in a suspension state, and heat to 5℃.

[0066] Step 4: Prepare sulfonyl chloride solution: Add 12g sulfonyl chloride to 30g n-hexane. Add the sulfonyl chloride solution dropwise at 5℃, controlling the dropping rate, and complete the addition in 1 hour. Then raise the temperature to 30℃ and continue the reaction for 3 hours.

[0067] Step 5: After washing, drying and vacuum distilling the reaction mixture, 45.65 g of modified DPP-based 254 pigment was obtained, which was brownish-yellow and had a yield of 97.50%.

[0068] Structural assessment:

[0069] (1) Elemental analysis of modified DPP-based 254 pigment:

[0070] Molecular formula: C 28 H 26 O6N2Cl2, molecular weight 557.42.

[0071] Theoretical calculations: C 60.33%; H 4.70%; O 17.22%; N 5.02%.

[0072] Actual measured values: C 60.29%; H 4.58%; O 17.20%; N 5.01%.

[0073] The actual measured values ​​are basically consistent with the theoretical calculated values.

[0074] (2) Infrared spectral determination of modified DPP-based 254 pigment:

[0075] IR (iquid film):υ c＝c :1605,1506;υ c＝o :1865,1805,1732,1696;υ as c-o-c :1203,1156;

[0076] υ c-o :1154,1060;υ c-N :1171,1023;δ c-cl :750,703.

[0077] (3) 1H NMR spectrum of modified DPP-based 254 pigment:

[0078] 1 H-NMR(CDCl3): 7.68(d, 4H); 7.47(d, 4H); 1.45(s, 18H)

[0079] As can be seen from the above structural identification results, the brownish-yellow product obtained in this embodiment is the target product modified DPP-based 254 pigment.

[0080] Example 3:

[0081] This embodiment provides a method for modifying DPP-based pigments with tert-butanol alkali metal salt, the method comprising the following steps:

[0082] Step 1: Add 200g of dichloroethane to the reaction vessel, purge with anhydrous nitrogen three times, add 20g of sodium tert-butoxide, stir well, and cool to 0℃.

[0083] Step two: Introduce anhydrous carbon dioxide at a rate of 0.1 L / min to initiate the reaction. Observe the tail gas; initially, no gas is released. After 1 hour of aeration, gas release begins. Continue introducing carbon dioxide for another 0.5 hours, then stop aeration.

[0084] Step 3: Slowly add 28g of DPP 255 pigment, stir until it is in a suspension state, and heat to 10℃.

[0085] Step 4: Prepare sulfonyl chloride solution: Add 13g sulfonyl chloride to 50g dichloroethane. At 10℃, add the sulfonyl chloride solution dropwise, controlling the dropping rate, and complete the addition in 1 hour. Then, raise the temperature to 30℃ and continue the reaction for 3 hours.

[0086] Step 5: After washing, drying and vacuum distilling the reaction mixture, 45.1 g of modified DPP-based 255 pigment was obtained, which was dark green and had a yield of 95.05%.

[0087] Structural assessment:

[0088] (1) Elemental analysis of modified DPP-based 255 pigment:

[0089] Molecular formula: C 28 H 28 O6N2, molecular weight 488.53.

[0090] Theoretical calculations: C 68.84%; H 5.78%; O 19.65%; N 19.65%.

[0091] Actual measured values: C 68.66%; H 5.51%; O 19.59%; N 19.58%.

[0092] The actual measured values ​​are basically consistent with the theoretical calculated values.

[0093] (2) Infrared spectral determination of modified DPP-based 255 pigment:

[0094] IR (iquid film):υ c＝c :1606,1508;υ c＝o :1860,1802,1731,1696;υ as c-o-c :1201,1160;

[0095] υ c-o :1149,1063;υ c-N :1171,1020.

[0096] (3) 1H NMR spectrum of modified DPP-based 255 pigment:

[0097] 1H-NMR (CDCl3): 7.75 (d, 4H); 7.48-7.50 (m, 6H); 1.44 (s, 18H)

[0098] As can be seen from the above structural identification results, the dark green product obtained in this embodiment is the target product modified DPP-based 255 pigment.

[0099] Example 4:

[0100] This embodiment provides a method for modifying DPP-based pigments with tert-butanol alkali metal salt, the method comprising the following steps:

[0101] Step 1: Add 150g of petroleum ether to the reactor, purge with anhydrous nitrogen three times, add 20g of potassium tert-butoxide, stir well, and cool to 0℃.

[0102] Step two: Introduce anhydrous carbon dioxide at a rate of 0.1 L / min to initiate the reaction. Observe the tail gas; initially, no gas is released. After 45 minutes of aeration, gas release begins. Continue introducing carbon dioxide for another 0.5 hours, then stop aeration.

[0103] Step 3: Slowly add 25g of DPP 255 pigment, stir until it is in a suspension state, and heat to 5℃.

[0104] Step 4: Prepare sulfonyl chloride solution: Add 12g sulfonyl chloride to 35g petroleum ether. Add the sulfonyl chloride solution dropwise at 5℃, controlling the dropping rate, and complete the addition in 1 hour. Then raise the temperature to 35℃ and continue the reaction for 3 hours.

[0105] Step 5: After washing, drying and vacuum distilling the reaction mixture, 41.52 g of modified DPP-based 255 pigment was obtained, which was dark green and had a yield of 98.02%.

[0106] Structural assessment:

[0107] (1) Elemental analysis of modified DPP-based 255 pigment:

[0108] Molecular formula: C 28 H 28 O6N2, molecular weight 488.53.

[0109] Theoretical calculations: C 68.84%; H 5.78%; O 19.65%; N 19.65%.

[0110] Actual measured values: C 68.66%; H 5.51%; O 19.59%; N 19.58%.

[0111] The actual measured values ​​are basically consistent with the theoretical calculated values.

[0112] (2) Infrared spectral determination of modified DPP-based 255 pigment:

[0113] IR (iquid film):υ c＝c :1605,1507;υ c＝o :1861,1803,1730,1698;υ as c-o-c :1200,1161;

[0114] υ c-o :1147,1061;υ c-N :1172,1019.

[0115] (3) 1H NMR spectrum of modified DPP-based 255 pigment:

[0116] 1 H-NMR (CDCl3): 7.74 (d, 4H); 7.49-7.51 (m, 6H); 1.43 (s, 18H)

[0117] As can be seen from the above structural identification results, the dark green product obtained in this embodiment is the target product modified DPP-based 255 pigment.

[0118] Performance testing:

[0119] (1) Solubility test:

[0120] The solubility properties of the DPP-based 254 pigment and the modified DPP-based 254 pigment in Example 1 are shown in Table 1.

[0121] Table 1 Solubility of Pigments in Example 1

[0122] solvent Solubility of DPP-based 254 pigment at 25℃ Modified DPP-based 254 pigment, 25℃ water 0.004g / L 35g / L xylene 0.006g / L 46g / L Cyclopentanone 0.007g / L 138g / L

[0123] As can be seen from Table 1, the solubility of DPP-based 254 pigment is significantly improved after modification compared to before modification.

[0124] The solubility properties of the DPP-based 254 pigment and the modified DPP-based 254 pigment in Example 2 are shown in Table 2.

[0125] Table 2 Solubility of Pigments in Example 2

[0126] solvent Solubility of DPP-based 254 pigment at 25℃ Modified DPP-based 254 pigment, 25℃ water 0.005g / L 38g / L xylene 0.007g / L 49g / L Cyclopentanone 0.008g / L 146g / L

[0127] As can be seen from Table 2, the solubility of DPP-based 254 pigment is significantly improved after modification compared to before modification.

[0128] The dispersion and dissolution properties of the DPP-based 255 pigment and the modified DPP-based 254 pigment in Example 3 are shown in Table 3.

[0129] Table 3 Solubility of Pigments in Example 3

[0130] solvent DPP-based 255 pigment solubility at 25℃ Modified DPP-based 255 pigment, 25℃ water 0.006g / L 45g / L xylene 0.008g / L 56g / L Cyclopentanone 0.009g / L 146g / L

[0131] As can be seen from Table 3, the solubility of DPP-based 255 pigment is significantly improved after modification compared to before modification.

[0132] The solubility properties of the DPP-based 255 pigment and the modified DPP-based 254 pigment in Example 4 are shown in Table 4.

[0133] Table 4 Solubility of Pigments in Example 4

[0134] solvent DPP-based 255 pigment solubility at 25℃ Modified DPP-based 255 pigment, 25℃ water 0.006g / L 48g / L xylene 0.007g / L 59g / L Cyclopentanone 0.009g / L 143g / L

[0135] As can be seen from Table 4, the solubility of DPP-based 255 pigment is significantly improved after modification compared to before modification.

[0136] (2) Performance test of restoring to the parent pigment:

[0137] Take 20 grams of the modified DPP-based 254 pigment obtained in Example 1 and place it in a single-necked flask. Heat it in an open-mouthed oil bath at 120°C. The system gradually turns red. After 1 hour, the color no longer deepens and remains bright red. The resulting bright red product is as shown in the figure. Figure 1 The X-ray diffraction pattern shown is from Figure 1 As can be seen, the bright red product obtained is consistent with the color of the standard DPP-based 254 pigment, which is the DPP-based 254 pigment. After cooling, 12.64g of DPP-based 254 pigment was weighed, with a yield of 98.60%.

[0138] Take 20 grams of the modified DPP-based 254 pigment obtained in Example 2 and place it in a single-necked flask. Heat it in an open-mouthed oil bath at 130°C. The system gradually turns red. After 1 hour, the color no longer deepens and remains bright red. The resulting bright red product is as shown in the figure. Figure 1 The X-ray diffraction pattern shown is from Figure 1 As can be seen, the bright red product obtained is consistent with the color of the standard DPP-based 254 pigment, which is the DPP-based 254 pigment. After cooling, 12.54 g of DPP-based 254 pigment was weighed, with a yield of 98.0%.

[0139] Take 20 grams of the modified DPP-based 255 pigment obtained in Example 3 and place it in a single-necked flask. Heat it in an open-mouthed oil bath at 120°C. The system gradually turns red. After 1 hour, the color no longer deepens and becomes a bright yellow-red. The resulting bright yellow-red product is as follows. Figure 2 The X-ray diffraction pattern shown is from Figure 2As can be seen from the results, the bright yellow-red product obtained is consistent with the color of the standard DPP-based 255 pigment, which is the DPP-based 254 pigment. After cooling, 11.39g of DPP-based 255 pigment was obtained by weighing, with a yield of 96.51%.

[0140] Take 20 grams of the modified DPP-based 255 pigment obtained in Example 4 and place it in a single-necked flask. Heat it in an open-mouthed oil bath at 120°C. The system gradually turns red. After 1 hour, the color no longer deepens and becomes a bright yellow-red. The resulting bright yellow-red product is as follows. Figure 2 The X-ray diffraction pattern shown is from Figure 2 As can be seen from the results, the bright yellow-red product obtained is consistent with the color of the standard DPP-based 255 pigment, which is the DPP-based 254 pigment. After cooling, 11.60g of DPP-based 255 pigment was obtained by weighing, with a yield of 98.50%.

[0141] (3) Dispersion performance test:

[0142] The dispersion performance was measured using a photometer according to GB / T 13451.2-1992, "Determination of Relative Tinting Strength of Coloring Pigments and Relative Scattering Strength of White Pigments". The modified pigments from Examples 1 to 4 were used as test samples, and the unmodified DPP-based 254 and DPP-based 255 pigments were used as standard samples. The relative tinting strength and relative scattering strength were used to measure the dispersion performance. The experiments are as follows:

[0143] (3.1) Determination of relative tinting strength K t :

[0144] Take 40g of R-type peptide dioxide, 56g of alkyd resin and 4g of calcium stearate and mix them. Use a mixing knife to mix the above components evenly, and then grind them on a three-roll mill until the fineness tested on the fineness plate is less than 15um, and then stop to obtain white paste.

[0145] Weigh 3 grams of white paste and 0.12 g of test sample. Place the white paste in the center of the lower plate of the automatic grinder, sprinkle the test sample on the white paste, and gently mix with a spatula. Close the grinder plate and grind four times with a force of 1 kN, 25 revolutions per pass. Set aside the collected dispersion. Transfer the sample dispersion and standard dispersion to the film container, ensuring that the exposed surfaces are uniform and level. Measure the R0 of each film using a spectrophotometer. ∞ or ρ ∞ (That is, at the wavelength where absorption is maximum, take the minimum value R) ∞ or ρ ∞ ), and calculate the relative tinting strength.

[0146] (3.2) Relative scattering force S t Measurement:

[0147] Using a mixing knife, 18.7 g of lampblack-type high-pigment carbon black was mixed with 81.3 g of alkyd resin, and the mixture was rolled six times on a three-roll mill to obtain a uniform fine dispersion. 3.25 g of this dispersion was then mixed with 91.64 g of alkyd resin and 5.11 g of synthetic silica. The mixture was then passed through a three-roll mill to obtain a black pigment paste.

[0148] Weigh 2.5 grams of black pulp and 2 grams of test sample. Place the black pulp in the center of the lower plate of the automatic grinder, mix the sample and pulp evenly, close the grinding plate, apply 1 kN of force and grind 4 times, 25 revolutions per pass, collect the dispersion and set aside for later use.

[0149] The sample dispersion and standard dispersion were transferred to separate film containers, ensuring the exposed surfaces were uniform and level. The R0 of each film was measured using a spectrophotometer at a wavelength of 550 nm. ∞ or ρ ∞ (That is, at the wavelength where absorption is maximum, take the minimum value R) ∞ or ρ ∞ The relative tinting strength was calculated. The results are shown in Table 5.

[0150] Table 5 shows the relative tinting strength of each pigment.

[0151]

[0152] Table 5 shows that the modified pigments have increased relative tinting strength and relative scattering strength by tens of times compared with the unmodified pigments, indicating that the dispersion performance has been significantly improved.

Claims

1. A method for modifying DPP-based pigments with tert-butanol alkali metal salt, wherein the method uses DPP-based pigments as raw materials, characterized in that... This method also uses tert-butanol alkali metal salt, carbon dioxide, and sulfonyl chloride as raw materials; and an aprotic solvent as the solvent. The method first synthesizes a salt containing tert-butoxycarbonyl, and then uses the tert-butoxycarbonyl in the salt to modify the imino group in the DPP pigment molecule to obtain a modified DPP pigment.

2. The method for modifying DPP pigments with tert-butanol alkali metal salt as described in claim 1, characterized in that, The DPP-based pigment is either DPP-based 254 pigment or DPP-based 255 pigment.

3. The method for modifying DPP pigments with tert-butanol alkali metal salt as described in claim 1, characterized in that, The alkali metal salt of tert-butanol is sodium tert-butanol or potassium tert-butanol.

4. The method for modifying DPP pigments with tert-butanol alkali metal salt as described in claim 1, characterized in that, The aprotic solvent is dichloromethane, dichloroethane, carbon tetrachloride, n-hexane, or petroleum ether.

5. The method for modifying DPP pigments with tert-butanol alkali metal salt as described in claim 1, characterized in that, The method includes the following steps: Step 1: Add the aprotic solvent into the reaction vessel, replace it with anhydrous nitrogen three times, add the tert-butanol alkali metal salt, stir evenly, and cool to -10 to 5℃. Step 2: Introduce anhydrous carbon dioxide and carry out the reaction at a reaction temperature of -10 to 5°C. Observe the tail gas. Initially, no gas is released. Once gas is released, continue to introduce carbon dioxide and react for another 0.5 hours, then stop introducing the gas. Step 3: Add DPP-based pigments and stir until a suspension is formed; then heat to 0-10°C. Step 4: Add sulfonyl chloride solution diluted with an aprotic solvent dropwise over 1-2 hours. Then, raise the temperature to 25-35°C and continue the reaction for 3 hours. Step 5: After the reaction is complete, the reaction system is washed with water, dried, and vacuum distilled to obtain the modified DPP pigment.

6. The method for modifying DPP pigments with tert-butanol alkali metal salt as described in claim 5, characterized in that, In step one, the mass ratio of tert-butanol alkali metal salt to aprotic solvent is 1:(10-20).

7. The method for modifying DPP pigments with tert-butanol alkali metal salt as described in claim 5, characterized in that, In step three, the molar ratio of DPP pigment to carbon dioxide is 1:(3.0~5.0); the molar ratio of DPP pigment to tert-butanol alkali metal salt is 1:(2.0~3.5); and the reaction temperature is 0~10℃.

8. The method for modifying DPP pigments with tert-butanol alkali metal salt as described in claim 5, characterized in that, In step three, the purity of the tert-butanol alkali metal salt is >99 wt.%, and the free alkali is <1 wt.%.

9. The method for modifying DPP pigments with tert-butanol alkali metal salt as described in claim 5, characterized in that, In step four, the molar ratio of DPP pigment to sulfonyl chloride is 1:(1.0~1.75).

10. The method for modifying DPP pigments with tert-butanol alkali metal salt as described in claim 5, characterized in that, In step four, the amount of aprotic solvent added is 3 to 5 times the mass of sulfonyl chloride.

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