A method for preparing and using a copolymer dispersant

Abstract

This invention relates to a method for preparing a copolymer dispersant and its application. The method for preparing the copolymer dispersant includes the following steps: (1) imidizing an alkyl anhydride containing a carbon-carbon double bond with an amino alcohol to obtain an alcohol containing an imide group and a carbon-carbon double bond; (2) modifying the alcohol containing an imide group and a carbon-carbon double bond obtained in step (1) with an alkyl sulfonate lactone to prepare a polymer unit B; (3) subjecting polymer unit A and polymer unit B obtained in step (2) to free radical polymerization to obtain the copolymer dispersant; wherein polymer unit A is a compound containing an alkenyl group and a phenyl group. The copolymer dispersant provided by this invention exhibits excellent dispersion stability for organic pigments when used in the preparation of aqueous color pastes.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of color paste auxiliary agents, in particular to a preparation method and application of a copolymer dispersant. BACKGROUND

[0002] Organic pigments have bright colors and strong tinting strength, and are widely used in color paste. However, most organic pigments are not water-soluble, and the use of organic pigments in water-based color paste can cause agglomeration, stratification and poor dispersion of organic pigment particles, thereby affecting the use effect of water-based color paste.

[0003] CN113634191A discloses a water-based dispersant of a comb-type alkyl phenol polyoxyethylene ether, which is non-ionic and contains anchoring groups and hydrophilic groups in its molecular structure. The anchoring groups are alkyl phenol pentamer segments, and the hydrophilic groups are polyoxyethylene ether segments. The molar ratio of the anchoring groups to the hydrophilic groups is 1:60-75. The water-based dispersant of the comb-type alkyl phenol polyoxyethylene ether has excellent tinting strength and water resistance, stable color phase, reduces floating color and blooming, and can be used to prepare stable high-solid low-viscosity water-based pigment concentrate paste. It can be used for dispersing organic pigments in resin-free systems, especially difficult-to-disperse carbon black and phthalocyanine pigments. However, the water-based dispersant of the comb-type alkyl phenol polyoxyethylene ether requires a large amount when used for dispersing paste, and the particle size of the color paste is still large, and the dispersion effect still needs to be improved.

[0004] Therefore, there is a need to develop a dispersant that can effectively improve the dispersion effect of insoluble organic pigments in water-based color paste. SUMMARY

[0005] To solve the above technical problems, the present application provides a preparation method and application of a copolymer dispersant, which has excellent dispersion stability for organic pigments, especially for difficult-to-disperse organic pigments such as phthalocyanine blue.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a preparation method of a copolymer dispersant, which comprises the following steps: (1) imidization of a cyclic anhydride containing a carbon-carbon double bond with an amino alcohol to obtain an alcohol containing an imide group and a carbon-carbon double bond; (2) modification of the alcohol containing an imide group and a carbon-carbon double bond obtained in step (1) with an alkyl sulfonic acid lactone to prepare a polymer unit B; and (3) free radical polymerization of the polymer unit A and the polymer unit B obtained in step (2) to obtain the copolymer dispersant. The polymer unit A is a compound containing an alkenyl group and a phenyl group.

[0008] In this invention, the large π bond provided by the planar structure of the benzene ring in polymer unit A and the nitrogen-containing heterocycle containing imide groups in polymer unit B can improve the anchoring ability of the copolymer dispersant to organic pigments. The sulfonic acid groups in polymer unit B can enable the copolymer dispersant to have excellent wettability and electrostatic repulsion ability on the surface of organic pigment particles, so that the copolymer dispersant can achieve excellent dispersion stability of organic pigments even without polyether compounds or polyether segments.

[0009] Preferably, the cyclic anhydride containing carbon-carbon double bonds has the structure shown in Formula 1 and / or Formula 2.

[0010] , .

[0011] In Formulas 1 and 2, R1, R2, R3, R4 and R5 are each independently selected from hydrogen or alkyl groups having 1 to 10 carbon atoms (e.g., 2, 3, 4, 5, 6, 7, 8 or 9).

[0012] Preferably, the amino alcohol includes any one or a combination of at least two of isopropanolamine, monoethanolamine, n-propanolamine, isobutanolamine, or 2-aminobutanol.

[0013] Preferably, the alkyl sulfonate lactone includes propanesulfonate lactone and / or butanesulfonate lactone, and more preferably propanesulfonate lactone.

[0014] Preferably, the compound containing alkenyl and phenyl groups includes any one or a combination of at least two of styrene, β-methylstyrene, allylbenzene, 3-methylstyrene, or 2-methylstyrene.

[0015] Preferably, the cyclic anhydride containing carbon-carbon double bonds includes any one or a combination of at least two of maleic anhydride, itaconic anhydride, or citraconic anhydride.

[0016] Preferably, the propanesulfonate lactone includes any one or a combination of at least two of 1,3-propanesulfonate lactone, 1-methyl-1,3-propanesulfonate lactone, 2-methyl-1,3-propanesulfonate lactone, or 3-methyl-1,3-propanesulfonate lactone.

[0017] Preferably, the butyryl lactone comprises any one or a combination of at least two of 1,4-butyryl lactone, 1-methyl-1,4-butyryl lactone, 2-methyl-1,4-butyryl lactone, 3-methyl-1,4-butyryl lactone or 4-methyl-1,4-butyryl lactone.

[0018] Preferably, the molar ratio of the cyclic anhydride containing carbon-carbon double bonds to the amino alcohol in step (1) is 1:(1~3), for example, 1:1.2, 1:1.4, 1:1.6, 1:1.8, 1:2.0, 1:2.2, 1:2.4, 1:2.6 or 1:2.8, etc.

[0019] Preferably, the molar ratio of the alcohol containing imide and carbon-carbon double bond to the alkyl sulfonate lactone in step (2) is 1:(1~1.5), for example 1:1.05, 1:1.1, 1:1.15, 1:1.2, 1:25, 1:1.3, 1:1.35, 1:1.4 or 1:1.45, etc.

[0020] Preferably, the molar ratio of polymerization unit A and polymerization unit B in step (3) is 1:(1~5), such as 1:1.5, 1:2, 1:2.5, 1:3, 1:3.5, 1:4 or 1:4.5, etc.

[0021] In this invention, the molar ratio of polymeric unit A to polymeric unit B is preferably 1:(1~5). If the proportion of polymeric unit B is too high, the hydrophilicity of the copolymer dispersant will be too strong, resulting in poor adsorption of pigment powder and thus poor dispersion of organic pigment. If the proportion of polymeric unit B is too low, the lipophilicity of the copolymer dispersant will be too strong, resulting in a decrease in the wetting ability and electrostatic steric hindrance repulsion of the copolymer dispersant on organic pigment, which will also lead to poor dispersion of organic pigment.

[0022] Preferably, step (1) includes mixing a cyclic anhydride containing a carbon-carbon double bond, an amino alcohol, and solvent A to carry out a first reaction and a second reaction to obtain the alcohol containing an imide group and a carbon-carbon double bond.

[0023] Preferably, in step (1), the first reaction and the second reaction are carried out under reflux and nitrogen protection conditions.

[0024] Preferably, in step (1), the temperature of the first reaction is 50~80℃ (e.g., 53℃, 56℃, 59℃, 62℃, 65℃, 68℃, 71℃, 74℃ or 77℃, etc.), and the time of the first reaction is 1~2 h (e.g., 1.1 h, 1.2 h, 1.3 h, 1.4 h, 1.5 h, 1.6 h, 1.7 h, 1.8 h or 1.9 h, etc.).

[0025] Preferably, the temperature of the second reaction in step (1) is 120~160℃ (e.g., 125℃, 130℃, 135℃, 140℃, 145℃, 150℃ or 155℃, etc.), and the time of the second reaction is 2~10 h (e.g., 3 h, 4 h, 5 h, 6 h, 7 h, 8 h or 9 h, etc.).

[0026] Preferably, step (1) further includes removing solvent A by vacuum distillation after the second reaction.

[0027] Preferably, the mass ratio of solvent A in step (1) to the total mass of cyclic anhydride and amino alcohol containing carbon-carbon double bonds is (1~5):1, for example 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1 or 4.5:1, etc.

[0028] Preferably, solvent A in step (1) includes any one or a combination of at least two of dimethylformamide, dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide or N-methylpyrrolidone.

[0029] Preferably, step (2) includes mixing the alcohol containing imide groups and carbon-carbon double bonds obtained in step (1), alkyl sulfonate lactone, solvent B and acid catalyst, and reacting them to obtain the polymer unit B.

[0030] In this invention, the hydroxyl groups and alkyl sulfonates in the alcohol containing imide groups and carbon-carbon double bonds undergo ring-opening esterification under the action of an acid catalyst, and the resulting polymer unit B contains imide groups and carbon-carbon double bonds, which can undergo free radical polymerization with polymer unit A.

[0031] Preferably, the reaction in step (2) is carried out under reflux and nitrogen protection conditions.

[0032] Preferably, the reaction temperature in step (2) is 60~90℃ (e.g., 63℃, 66℃, 69℃, 72℃, 75℃, 78℃, 81℃, 84℃ or 87℃, etc.), and the reaction time is 5~20 h (e.g., 7 h, 9 h, 11 h, 13 h, 15 h, 17 h or 19 h, etc.).

[0033] Preferably, the reaction in step (2) is carried out until the residual amount of alkyl sulfonate lactone is <0.5%, for example 0.1%, 0.2%, 0.3% or 0.4%.

[0034] In this invention, the residual amount of alkyl sulfonate lactone refers to the percentage by mass of the remaining alkyl sulfonate lactone in the reaction system relative to the alkyl sulfonate lactone added to the system.

[0035] Preferably, step (2) further includes removing solvent B by vacuum distillation after the reaction.

[0036] Preferably, the mass ratio of solvent B in step (2) to the total mass of alcohols and alkyl sulfonates containing imide groups and carbon-carbon double bonds is (1~5):1, for example 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1 or 4.5:1, etc.

[0037] Preferably, the mass of the acid catalyst in step (2) is 0.2% to 1% of the total mass of alcohols and alkyl sulfonates containing imide groups and carbon-carbon double bonds, such as 0.3%, 0.4%, 0.5%, 0.6%, 0.7%, 0.8% or 0.9%.

[0038] Preferably, solvent B comprises any one or a combination of at least two of dimethylformamide, dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, or N-methylpyrrolidone.

[0039] Preferably, the acid catalyst comprises any one or a combination of at least two of toluenesulfonic acid, sulfuric acid, propionic acid, or hydrochloric acid.

[0040] Preferably, step (3) includes mixing polymerization unit A, polymerization unit B obtained in step (2), initiator and solvent C to form a mixture, adding it dropwise to solvent D, reacting, and obtaining the copolymer dispersant.

[0041] Preferably, the addition and reaction in step (3) are carried out under nitrogen protection.

[0042] Preferably, the temperature of the dripping in step (3) is 60~100℃ (e.g., 65℃, 70℃, 75℃, 80℃, 85℃, 90℃ or 95℃, etc.), and the dripping time is 2~10 h, e.g., 3 h, 4 h, 5 h, 6 h, 7 h, 8 h or 9 h, etc.

[0043] Preferably, the reaction temperature in step (3) is 60~100℃ (e.g., 65℃, 70℃, 75℃, 80℃, 85℃, 90℃ or 95℃, etc.), and the reaction time is 1~5 h, e.g., 1.5 h, 2 h, 2.5 h, 3 h, 3.5 h, 4 h or 4.5 h, etc.

[0044] In this invention, the dropwise addition process in step (3) is a semi-continuous reaction, and after the dropwise addition is completed, a constant temperature reaction is carried out.

[0045] Preferably, the ratio of the total mass of solvent C and solvent D in step (3) to the total mass of polymerization unit A and polymerization unit B is (1~5):1, for example 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1 or 4.5:1, etc.

[0046] Preferably, the mass ratio of solvent C to solvent D is (0.8~1.2):1, for example, 0.85:1, 0.9:1, 0.95:1, 1:1, 1.05:1, 1.1:1 or 1.15:1, etc.

[0047] Preferably, solvent C and solvent D each independently comprise any one or a combination of at least two of 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, o-xylene, m-xylene, p-xylene, ethylbenzene, or toluene.

[0048] Preferably, the initiator comprises any one or a combination of at least two of dimethyl azobisisobutyrate, azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovalerate, azoisobutylcyanoformamide, or azobiscyclohexylformitrile.

[0049] Preferably, the mass of the initiator is 0.5% to 2% of the total mass of polymerization unit A and polymerization unit B, for example, 0.7%, 0.9%, 1.1%, 1.3%, 1.5%, 1.7% or 1.9%.

[0050] In a second aspect, the present invention provides a copolymer dispersant, which is prepared by the preparation method described in the first aspect.

[0051] Thirdly, the present invention provides the application of the copolymer dispersant as described in the first aspect in the dispersion of organic pigments.

[0052] Preferably, the organic pigment includes phthalocyanine blue.

[0053] Compared with the prior art, the present invention has at least the following beneficial effects:

[0054] This invention involves reacting a cyclic acid anhydride containing a carbon-carbon double bond with an amino alcohol imidizing agent to obtain an alcohol containing an imide group and a carbon-carbon double bond, which is then modified with an alkyl sulfonate lactone to form a polymer unit B. Polymer unit B and polymer unit A are then subjected to free radical polymerization to obtain a copolymer dispersant. This copolymer dispersant exhibits excellent dispersion stability for organic pigments, especially phthalocyanine blue. Adding the copolymer dispersant to aqueous color pastes can improve the dispersion effect of organic pigments. Detailed Implementation

[0055] To facilitate understanding of the present invention, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of the invention.

[0056] Example 1

[0057] This embodiment provides a copolymer dispersant and its preparation method. The preparation method of the copolymer dispersant includes the following steps:

[0058] (1) In a reflux reflux flask under nitrogen protection, add a cyclic anhydride containing carbon-carbon double bonds (maleic anhydride) and solvent A (dimethylformamide), heat to 60°C and stir to dissolve, then add an amino alcohol (isopropanolamine) and keep the reaction at the temperature for 1.5 h. The molar ratio of the cyclic anhydride containing carbon-carbon double bonds to the amino alcohol is 1:2, and the mass ratio of solvent A to the total mass of the cyclic anhydride containing carbon-carbon double bonds and the amino alcohol is 3:1.

[0059] The temperature was then raised to 140°C and reacted for 6 h. Solvent A was removed by vacuum distillation to obtain the alcohol containing imide groups and carbon-carbon double bonds.

[0060] (2) In a reflux reflux flask under nitrogen protection, add the alcohol containing imide groups and carbon-carbon double bonds, alkyl sulfonate lactone (1,3-propanesulfonate lactone), and solvent B (dimethylformamide) obtained in step (1) and stir evenly at 80°C. Add acid catalyst (toluenesulfonic acid) and mix. The molar ratio of the alcohol containing imide groups and carbon-carbon double bonds to the alkyl sulfonate lactone is 1:1. The mass ratio of solvent B to the total mass of the alcohol containing imide groups and carbon-carbon double bonds and the alkyl sulfonate lactone is 3:1. The mass of the acid catalyst is 0.5% of the total mass of the alcohol containing imide groups and carbon-carbon double bonds and the alkyl sulfonate lactone. Stir the reaction at a constant temperature for 5 hours. Remove solvent B by vacuum distillation to obtain the polymer unit B.

[0061] (3) In a nitrogen-protected reaction flask, solvent D (1,2,4-trimethylbenzene) is stirred and heated to 80°C. Then, a mixture of polymer unit A (styrene), polymer unit B obtained in step (2), initiator (dimethyl azobisisobutyrate), and solvent C (1,2,4-trimethylbenzene) is uniformly added dropwise. The molar ratio of polymer unit A to polymer unit B is 1:3. The ratio of the total mass of solvent C and solvent D to the total mass of polymer unit A and polymer unit B is 3:1. The mass ratio of solvent C to solvent D is 1:1. The mass of the initiator is 1% of the total mass of polymer unit A and polymer unit B. The addition is completed within 5 h. The reaction is kept at the temperature for 4 h. Solvent C is removed by vacuum distillation to obtain the copolymer dispersant.

[0062] Example 2

[0063] This embodiment provides a copolymer dispersant and its preparation method. The preparation method of the copolymer dispersant includes the following steps:

[0064] (1) In a reflux condenser under nitrogen protection, add a cyclic anhydride containing carbon-carbon double bonds (citric acid) and solvent A (dimethylacetamide), heat to 50°C and stir to dissolve. Then add an amino alcohol (n-propanolamine) and keep the reaction at the temperature for 2 h. The molar ratio of the cyclic anhydride containing carbon-carbon double bonds to the amino alcohol is 1:1, and the mass ratio of solvent A to the total mass of the cyclic anhydride containing carbon-carbon double bonds and the amino alcohol is 1:1.

[0065] The temperature was then raised to 160°C and reacted for 4 h. Solvent A was removed by vacuum distillation to obtain the alcohol containing imide groups and carbon-carbon double bonds.

[0066] (2) In a reflux reflux flask under nitrogen protection, add the alcohol containing imide groups and carbon-carbon double bonds, alkyl sulfonate lactone (1,3-propanesulfonate lactone), and solvent B (dimethylformamide) obtained in step (1) and stir evenly at 60°C. Add acid catalyst (sulfuric acid) and mix. The molar ratio of the alcohol containing imide groups and carbon-carbon double bonds to the alkyl sulfonate lactone is 1:1.2. The mass ratio of solvent B to the total mass of the alcohol containing imide groups and carbon-carbon double bonds and the alkyl sulfonate lactone is 2:1. The mass of acid catalyst is 0.8% of the total mass of the alcohol containing imide groups and carbon-carbon double bonds and the alkyl sulfonate lactone. Stir the reaction at a constant temperature for 20 h, remove solvent B by vacuum distillation, and obtain the polymer unit B.

[0067] (3) In a nitrogen-protected reaction flask, solvent C (o-xylene) is stirred and heated to 70°C. Then, a mixture of polymer unit A (β-methylstyrene), polymer unit B obtained in step (2), initiator (azobisisobutyronitrile), and solvent D (o-xylene) is uniformly added dropwise. The molar ratio of polymer unit A to polymer unit B is 1:4. The ratio of the total mass of solvent C and solvent D to the total mass of polymer unit A and polymer unit B is 2:1. The mass ratio of solvent C to solvent D is 1:1. The mass of the initiator is 1.5% of the total mass of polymer unit A and polymer unit B. The addition is completed within 6 h. The reaction is kept at the temperature for 5 h. Solvent C is removed by vacuum distillation to obtain the copolymer dispersant.

[0068] Example 3

[0069] This embodiment provides a copolymer dispersant and its preparation method. The preparation method of the copolymer dispersant includes the following steps:

[0070] (1) In a reflux reflux flask under nitrogen protection, add a cyclic anhydride containing carbon-carbon double bonds (citric acid) and solvent A (dimethylacetamide), heat to 90°C and stir to dissolve, then add an amino alcohol (n-propanolamine) and keep the reaction at the temperature for 1 h. The molar ratio of the cyclic anhydride containing carbon-carbon double bonds to the amino alcohol is 1:3, and the mass ratio of solvent A to the total mass of the cyclic anhydride containing carbon-carbon double bonds and the amino alcohol is 4:1.

[0071] The temperature was then raised to 120°C and reacted for 8 hours. Solvent A was removed by vacuum distillation to obtain the alcohol containing imide groups and carbon-carbon double bonds.

[0072] (2) In a reflux reflux flask under nitrogen protection, add the alcohol containing imide groups and carbon-carbon double bonds, alkyl sulfonate lactone (2-methyl-1,3-propanesulfonate lactone) and solvent B (dimethylacetamide) obtained in step (1) and stir evenly at 90°C. Add acid catalyst (propionic acid) and mix. The molar ratio of the alcohol containing imide groups and carbon-carbon double bonds to the alkyl sulfonate lactone is 1:1.1. The mass ratio of solvent B to the total mass of the alcohol containing imide groups and carbon-carbon double bonds and the alkyl sulfonate lactone is 3:1. The mass of acid catalyst is 1% of the total mass of the alcohol containing imide groups and carbon-carbon double bonds and the alkyl sulfonate lactone. Stir the reaction at a constant temperature for 10 h. Remove solvent B by vacuum distillation to obtain the polymer unit B.

[0073] (3) In a nitrogen-protected reaction flask, solvent C (toluene) is stirred and heated to 90°C. Then, a mixture of polymer unit A (allylbenzene), polymer unit B obtained in step (2), initiator (azobisisoheptanenitrile), and solvent D (toluene) is uniformly added dropwise. The molar ratio of polymer unit A to polymer unit B is 1:2. The ratio of the total mass of solvent C and solvent D to the total mass of polymer unit A and polymer unit B is 4:1. The mass ratio of solvent C to solvent D is 1:1. The mass of the initiator is 0.8% of the total mass of polymer unit A and polymer unit B. The addition is completed within 7 h. The reaction is kept at the temperature for 3 h. Solvent C is removed by vacuum distillation to obtain the copolymer dispersant.

[0074] Example 4

[0075] This embodiment provides a copolymer dispersant and its preparation method. The difference between this embodiment and Example 1 is that the molar ratio of polymer unit A and polymer unit B in step (3) is adjusted to 1:1, and the conditions are the same as in Example 1.

[0076] Example 5

[0077] This embodiment provides a copolymer dispersant and its preparation method. The difference between this embodiment and Example 1 is that the molar ratio of polymer unit A and polymer unit B in step (3) is adjusted to 1:0.5, and the conditions are the same as in Example 1.

[0078] Example 6

[0079] This embodiment provides a copolymer dispersant and its preparation method. The difference between this embodiment and Example 1 is that the molar ratio of polymer unit A and polymer unit B in step (3) is adjusted to 1:6, and the conditions are the same as in Example 1.

[0080] Example 7

[0081] This embodiment provides a copolymer dispersant and its preparation method. The difference between this embodiment and Example 1 is that the amino alcohol (isopropanolamine) in step (1) is replaced with the same molar amount of amino alcohol (monoethanolamine), and the conditions are the same as in Example 1.

[0082] Example 8

[0083] This embodiment provides a copolymer dispersant and its preparation method. The difference between this embodiment and Example 1 is that the amino alcohol (isopropanolamine) in step (1) is replaced with the same molar amount of amino alcohol (isobutanolamine), and the conditions are the same as in Example 1.

[0084] Example 9

[0085] This embodiment provides a copolymer dispersant and its preparation method. The difference between this embodiment and Example 1 is that the alkyl sulfonate lactone (1,3-propanesulfonate lactone) in step (2) is replaced with the same molar amount of alkyl sulfonate lactone (1,4-butanesulfonate lactone), and the conditions are the same as in Example 1.

[0086] Example 10

[0087] This embodiment provides a copolymer dispersant and its preparation method. The difference between this embodiment and Example 1 is that the cyclic anhydride containing carbon-carbon double bonds (maleic anhydride) is replaced with the same molar amount of cyclic anhydride containing carbon-carbon double bonds (itaconic anhydride), and the conditions are the same as in Example 1.

[0088] Comparative Example 1

[0089] This comparative example provides a copolymer and its preparation method, which differs from Example 1 in that step (2) is not included, and the polymerization unit B in step (3) is replaced with the same molar amount of an alcohol containing an imide group and a carbon-carbon double bond, under the same conditions as in Example 1.

[0090] Comparative Example 2

[0091] This comparative example provides a copolymer and its preparation method, which differs from Example 1 in that step (1) is omitted, and the alcohol containing imide groups and carbon-carbon double bonds in step (2) is replaced with the same molar amount of N-hydroxymethylacrylamide, under the same conditions as in Example 1.

[0092] Comparative Example 3

[0093] This comparative example provides a copolymer and its preparation method, which differs from Example 1 in that step (1) is not included, and the alcohol containing imide groups and carbon-carbon double bonds in step (2) is replaced with the same molar amount of hydroxyethyl acrylate, under the same conditions as in Example 1.

[0094] Test Example 1

[0095] This test example provides an aqueous color paste, which is prepared by laboratory sand milling. Specifically, 5g of the copolymer dispersant provided in Example 1, 54.7g of water, 0.3g of ammonia (mass percentage concentration of 27%), and 40g of organic pigment (phthalocyanine blue 15:3) are stirred evenly. Then, 200g of zirconium beads with a particle size of 1.2-1.4 mm are added, sealed in a glass jar, shaken for 8 hours, and filtered to obtain the aqueous color paste.

[0096] Test Case 2 to Test Case 10

[0097] Test Examples 2 through 10 each provide an aqueous color paste, which differs from Test Example 1 in that the copolymer dispersant provided in Example 1 is replaced with the same mass of copolymer dispersant provided in Examples 2 through 10, while other conditions are the same as in Test Example 1.

[0098] Comparative Test Cases 1 to 3

[0099] Comparative Test Examples 1 to 3 each provide an aqueous color paste. The difference between them and Test Example 1 is that the copolymer dispersant provided in Example 1 is replaced with the same mass of the copolymers provided in Comparative Examples 1 to 3, while the other conditions are the same as those in Test Example 1.

[0100] The following performance tests were conducted on the water-based pigments provided in Test Examples 1 to 10 and Comparative Test Examples 1 to 3.

[0101] (1) Viscosity: Measured using an NDJ-1B rotational viscometer, Shanghai Changji Geological Instrument Co., Ltd.

[0102] (2) Particle size: Tested using a BT-90 laser particle size analyzer, Dandong Better Instruments Co., Ltd.

[0103] (3) Storage stability: Store at 55℃ for 7 days (55℃ / 7d), observe the state of the water-based pigment, and retest the particle size and viscosity.

[0104] (4) Centrifugal sedimentation rate: After centrifuging the water-based pigment at 4000 rpm for 20 minutes, wash it with anhydrous ethanol, dry it at 90℃ to constant weight, and accurately weigh the sediment; sedimentation rate = sedimentation weight ÷ (mass percentage of organic pigment in water-based pigment × water-based pigment sample amount) × 100%.

[0105] The test results are shown in Table 1 below.

[0106] Table 1

[0107]

[0108] In Table 1, "-" indicates that the test was not performed.

[0109] As can be seen from Table 1, the aqueous color pastes prepared by dispersing phthalocyanine blue 15:3 with the copolymer dispersants provided in Examples 1-10 have low viscosity, small particle size, initial viscosity of 121-354 mPa·s, initial particle size D50 of 208-372 nm, low centrifugal sedimentation rate, and the aqueous color pastes prepared are stored at 55℃ for 7 days with small changes in viscosity and particle size, and good stability. The copolymer dispersants provided in this invention have a good dispersion effect on aqueous color pastes of organic pigments.

[0110] A comparison between Test Example 5 and Test Example 1 shows that if the molar ratio of polymeric unit A to polymeric unit B is too high, the initial viscosity and 55℃ / 7d storage viscosity of the aqueous pigment will increase accordingly, the centrifugal sedimentation rate will increase, and the dispersion effect will decrease. A comparison between Test Example 6 and Test Example 1 shows that if the molar ratio of polymeric unit A to polymeric unit B is too low, the initial particle size of the aqueous pigment will increase, the 55℃ / 7d storage viscosity will increase, the centrifugal sedimentation rate will increase, and the dispersion effect will decrease. Therefore, it can be concluded that by controlling the molar ratio of polymeric unit A to polymeric unit B within a specific range, the copolymer dispersant prepared will have better performance.

[0111] The comparison between Comparative Test Example 1 and Test Example 2 shows that if the alkyl sulfonate lactone modification step is not included, the initial particle size D50 of the prepared water-based pigment is large, the viscosity is too high, other test items cannot be measured, and it has almost no dispersion effect on organic pigment (phthalocyanine blue 15:3).

[0112] As can be seen from the comparison between Test Example 2 and Test Example 1, if the cyclic anhydride containing carbon-carbon double bonds is reacted with amino alcohol imidized to obtain an alcohol containing imide groups and carbon-carbon double bonds, and replaced with N-hydroxymethylacrylamide, the resulting copolymer has poor dispersion ability for organic pigments (phthalocyanine blue 15:3).

[0113] The comparison between Test Example 3 and Test Example 1 shows that if the cyclic anhydride containing carbon-carbon double bonds is reacted with amino alcohol imidized to obtain an alcohol containing imide groups and carbon-carbon double bonds, and then replaced with hydroxyethyl acrylate, the initial particle size D50 of the prepared water-based pigment is larger, the viscosity is too high to be measured in other test items, and it has almost no dispersion effect on organic pigments (phthalocyanine blue 15:3).

[0114] The applicant declares that the above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A method for preparing a copolymer dispersant, characterized in that, The preparation method includes the following steps: (1) Cyclic acid anhydrides containing carbon-carbon double bonds undergo imidization with amino alcohols to obtain alcohols containing imide groups and carbon-carbon double bonds; (2) The alcohol containing imide groups and carbon-carbon double bonds obtained in step (1) is modified with alkyl sulfonate lactone to prepare polymer unit B; (3) Free radical polymerization is carried out on polymer unit A and polymer unit B obtained in step (2) to obtain the copolymer dispersant; The polymerization unit A is a compound containing an alkenyl group and a phenyl group; The molar ratio of the cyclic anhydride containing carbon-carbon double bonds to the amino alcohol in step (1) is 1:(1~3); The molar ratio of the alcohol containing imide groups and carbon-carbon double bonds to the alkyl sulfonate lactone in step (2) is 1:(1~1.5); The molar ratio of polymerization unit A and polymerization unit B in step (3) is 1:(1~5).

2. The preparation method according to claim 1, characterized in that, The cyclic anhydride containing carbon-carbon double bonds has the structure shown in Formula 1 and / or Formula 2: 、 ； R1, R2, R3, R4 and R5 are each independently selected from hydrogen or alkyl groups having 1 to 10 carbon atoms; The amino alcohol includes any one or a combination of at least two of isopropanolamine, monoethanolamine, n-propanolamine, isobutanolamine, or 2-aminobutanol; The alkyl sulfonate lactones include propanesulfonate lactone and / or butanesulfonate lactone. The compounds containing alkenyl and phenyl groups include any one or a combination of at least two of styrene, β-methylstyrene, allylbenzene, 3-methylstyrene, or 2-methylstyrene.

3. The preparation method according to claim 2, characterized in that, The cyclic anhydrides containing carbon-carbon double bonds include any one or a combination of at least two of maleic anhydride, itaconic anhydride, or citraconic anhydride. The propanesulfonate lactone includes any one or a combination of at least two of 1,3-propanesulfonate lactone, 1-methyl-1,3-propanesulfonate lactone, 2-methyl-1,3-propanesulfonate lactone or 3-methyl-1,3-propanesulfonate lactone. The butyryl lactone includes any one or a combination of at least two of 1,4-butyryl lactone, 1-methyl-1,4-butyryl lactone, 2-methyl-1,4-butyryl lactone, 3-methyl-1,4-butyryl lactone, or 4-methyl-1,4-butyryl lactone.

4. The preparation method according to claim 1, characterized in that, Step (1) includes mixing a cyclic acid anhydride containing a carbon-carbon double bond, an amino alcohol, and solvent A to carry out a first reaction and a second reaction to obtain the alcohol containing an imide group and a carbon-carbon double bond; Step (1) The first and second reactions are carried out under reflux and nitrogen protection conditions; In step (1), the temperature of the first reaction is 50~80℃, and the reaction time is 1~2 h; In step (1), the temperature of the second reaction is 120~160℃, and the time of the second reaction is 2~10 h; Step (1) after the second reaction further includes vacuum distillation to remove solvent A; In step (1), the mass ratio of solvent A to the total mass of cyclic anhydrides and amino alcohols containing carbon-carbon double bonds is (1~5):1; The solvent A in step (1) includes any one or a combination of at least two of dimethylformamide, dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide or N-methylpyrrolidone.

5. The preparation method according to claim 1, characterized in that, Step (2) involves mixing the alcohol containing imide groups and carbon-carbon double bonds obtained in step (1), alkyl sulfonate lactone, solvent B and acid catalyst, and reacting them to obtain the polymer unit B; The reaction described in step (2) is carried out under reflux and nitrogen protection conditions; The reaction temperature in step (2) is 60~90℃, and the reaction time is 5~20 h; Step (2) further includes removing solvent B by vacuum distillation after the reaction; In step (2), the mass ratio of solvent B to the total mass of alcohols and alkyl sulfonates containing imide groups and carbon-carbon double bonds is (1~5):

1. The mass of the acid catalyst in step (2) is 0.2% to 1% of the total mass of alcohols and alkyl sulfonates containing imide groups and carbon-carbon double bonds; Solvent B includes any one or a combination of at least two of dimethylformamide, dimethylacetamide, tetrahydrofuran, dimethyl sulfoxide, or N-methylpyrrolidone; The acid catalyst includes any one or a combination of at least two of toluenesulfonic acid, sulfuric acid, propionic acid, or hydrochloric acid.

6. The preparation method according to claim 1, characterized in that, Step (3) includes mixing polymerization unit A, polymerization unit B obtained in step (2), initiator and solvent C to form a mixture, adding it dropwise to solvent D, reacting, and obtaining the copolymer dispersant; The addition and reaction described in step (3) are carried out under nitrogen protection; The temperature for the dripping in step (3) is 60~100℃, and the dripping time is 2~10 h; The reaction temperature in step (3) is 60~100℃, and the reaction time is 1~5 h; In step (3), the ratio of the total mass of solvent C and solvent D to the total mass of polymerization unit A and polymerization unit B is (1~5):1; The mass ratio of solvent C to solvent D is (0.8~1.2):1; Solvent C and solvent D each independently include any one or a combination of at least two of 1,2,4-trimethylbenzene, 1,3,5-trimethylbenzene, o-xylene, m-xylene, p-xylene, ethylbenzene, or toluene; The initiator includes any one or a combination of at least two of the following: dimethyl azobisisobutyrate, azobisisobutyronitrile, azobisisoheptanenitrile, azobisisovalerate, azoisobutylcyanoformamide, or azobiscyclohexylformitrile. The mass of the initiator is 0.5% to 2% of the total mass of polymerization unit A and polymerization unit B.

7. A copolymer dispersant, characterized in that, The copolymer dispersant is prepared by the preparation method according to any one of claims 1 to 6.

8. The use of the copolymer dispersant as described in claim 7 in the dispersion of organic pigments.

9. The application according to claim 8, characterized in that, The organic pigments include phthalocyanine blue.

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