Preparation method of polyurethane polymeric dispersant for color paste

Abstract

The invention relates to the technical field of dispersants, and discloses a preparation method of a polyurethane polymeric dispersant for color paste.The preparation method comprises the steps that N-Boc-serinol is used as a chain extender to be subjected to a polymerization reaction with polyethylene glycol, isophorone diisocyanate and the like, then boc protection is removed, then the mixture is subjected to a polymerization reaction with mercaptoacetic acid and N, N-dimethylformamide, and the polyurethane polymeric dispersant for color paste is obtained. The preparation method comprises the following steps: reacting N, N-dimethyl ethylamino maleamic acid to obtain the polyurethane polymeric dispersant of which the side chain contains a tertiary amine group, a carboxyl group and an amido bond hydrophilic group. The dispersing agent contains tertiary amine anchoring groups which can interact with phthalocyanine blue and other pigments, the adsorption effect of the dispersing agent and the surface of the phthalocyanine blue pigment is enhanced, desorption is not prone to occurring, the dispersing agent contains carboxyl and amido bond hydrophilic groups, the dispersing agent has good hydrophilicity and water solubility, the dispersity and flocculation resistance of the phthalocyanine blue and other pigments are improved, and the service life of the dispersing agent is prolonged. Meanwhile, good centrifugal stability is shown.

Description

Technical Field

[0001] The invention relates to the technical field of dispersants, in particular to a method for preparing a polyurethane polymer dispersant for color paste. Background Art

[0002] Color paste is mainly composed of pigments, dispersants, etc., and is widely used in coatings, inks and other fields. Dispersants can inhibit the aggregation of pigments and reduce particle size, thereby obtaining color pastes with good dispersion. The dispersibility and stability of pigment particles have a great influence on the performance of coatings and inks. Therefore, high-performance dispersants have important applications.

[0003] The current dispersants mainly include polyacrylate type, polyurethane type, polyether type, etc. Among them, polyurethane type dispersants have good hydrophilicity, strong surface interaction force on pigments such as phthalocyanine blue, and are widely used. The development of new polyurethane dispersants is a research hotspot. Introducing anchoring groups into polyurethane dispersants can enhance the interaction between dispersants and pigment molecules, and can improve the dispersibility and stability of dispersants. The invention patent with announcement number CN111875777B discloses a water-based polymer polyurethane dispersant and a preparation method thereof, wherein aromatic hydrocarbon isocyanate is reacted with alkyl-terminated monohydroxy polyoxyethylene ether and monohydroxy tertiary amine, and pigment anchoring groups such as polyoxyethylene ether and tertiary amine are introduced into the polyurethane structure, so that the dispersant has excellent wetting and dispersing effect on inorganic carbon black. However, the polyurethane dispersant does not show good dispersibility for organic pigments such as phthalocyanine blue. Summary of the invention

[0004] The technical problem solved by the invention is to provide a polyurethane polymer dispersant for color paste with high dispersibility.

[0005] The technical solution of the present invention is: a method for preparing a polyurethane polymer dispersant for color paste, comprising the following steps:

[0006] Step (1), add dry polyethylene glycol and diisocyanate into a flask, heat to 70-80°C, stir and react for 2-3h, then add N-Boc-serinol and dibutyltin dilaurate, react for 1-1.5h, add dichloromethane and trifluoroacetic acid after cooling, stir and react for 4-6h, distill under reduced pressure, wash with sodium bicarbonate solution, and dry to obtain amino polyurethane.

[0007] Step (2), adding N,N-dimethylformamide, amino polyurethane, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and thioglycolic acid into a flask, stirring for reaction, distilling under reduced pressure, washing with methanol, and drying to obtain thioglycolamide polyurethane.

[0008] Step (3), adding tetrahydrofuran, mercaptoacetamide polyurethane, N,N-dimethylethylaminomaleamic acid, and benzoin dimethyl ether into a flask, placing the flask under a high-pressure mercury lamp for irradiation for 2-3 hours, distilling under reduced pressure, washing with methanol, and drying to obtain a polyurethane polymer dispersant for color paste.

[0009] Preferably, in step (1), the molar ratio of polyethylene glycol, diisocyanate and N-Boc-serinol is 1:(2.2-2.4):(1-1.2).

[0010] Preferably, the diisocyanate is isophorone diisocyanate or hexamethylene diisocyanate.

[0011] Preferably, in step (2), the mass ratio of amino polyurethane, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and thioglycolic acid is 100:(7.5-11.6):(13-19):(6-9).

[0012] Preferably, in step (2), the reaction is carried out at 20-35° C. for 3-5 h.

[0013] Preferably, in step (3), the mass ratio of mercaptoacetamide polyurethane, N,N-dimethylethylaminomaleamic acid, and benzoin dimethyl ether is 100:(8-14):(0.06-0.1).

[0014] Preferably, in step (3), the power of the high-pressure mercury lamp is 400-600 W, and the lamp distance is 10-15 cm.

[0015] Preferably, the preparation method of N,N-dimethylethylaminomaleamic acid is as follows: glacial acetic acid and N,N-dimethylethylenediamine and maleic anhydride in a mass ratio of 100:(125-140) are added to a flask, reacted at 30-40°C for 3-5h, filtered, vacuum dried, and the product is recrystallized in a mixed solution of methanol and ether to obtain N,N-dimethylethylaminomaleamic acid.

[0016] The technical effect produced by the present invention is as follows: the present invention uses N-Boc-serinol as a chain extender to carry out polymerization reaction with polyethylene glycol, isophorone diisocyanate and the like, then removes the Boc protection to obtain a polyurethane containing an amino group on the side chain, then carries out an amidation reaction with thioglycolic acid to obtain a polyurethane containing a thiol group, and finally, under the action of a photoinitiator of benzoin dimethyl ether, the thiol group and the olefinic group of N,N-dimethylethylaminomaleamic acid undergo a thiol-olefin click reaction to obtain a polyurethane polymer dispersant containing a tertiary amine group, a carboxyl group, and an amide bond hydrophilic group on the side chain.

[0017] The polyurethane polymer dispersant of the invention contains a tertiary amine anchoring group, which can interact with pigments such as phthalocyanine blue, enhance the adsorption effect between the dispersant and the surface of the phthalocyanine blue pigment, and is not easy to desorb. The dispersant contains carboxyl and amide bond hydrophilic groups, which make the dispersant have good hydrophilicity and water solubility. When the dispersant is adsorbed on the surface of the pigment molecules, a complete adsorption layer is formed, which has a strong hydrophilic effect and steric hindrance effect, prevents the aggregation of the pigment molecules, reduces the particle size of the pigment molecules, thereby improving the dispersibility and anti-flocculation of the pigments such as phthalocyanine blue, and exhibits good centrifugal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 This is the reaction formula for preparing N,N-dimethylethylaminomaleamic acid.

[0019] Figure 2 It is the reaction formula for preparing polyurethane polymer dispersant for color paste. DETAILED DESCRIPTION

[0020] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] Example 1

[0022] (1) Add 8 mL of glacial acetic acid, 0.6 g of N,N-dimethylethylenediamine, and 0.75 g of maleic anhydride to a flask, react at 35° C. for 5 h, filter, and vacuum dry. The product is recrystallized from a mixed solution of methanol and ether to obtain N,N-dimethylethylaminomaleamic acid.

[0023] (2) Add 20 mmol of dry polyethylene glycol 2000 and 46 mmol of isophorone diisocyanate into a flask, heat to 70°C, stir and react for 3 h, then add 22 mmol of N-Boc-serinol and 15 mg of dibutyltin dilaurate, react for 1 h, cool, add 300 mL of dichloromethane and 120 mL of trifluoroacetic acid, stir and react for 6 h, distill under reduced pressure, wash with sodium bicarbonate solution, and dry to obtain amino polyurethane.

[0024] (3) Add 100 mL of N,N-dimethylformamide, 10 g of amino polyurethane, 0.75 g of N-hydroxysuccinimide, 1.3 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 0.6 g of thioglycolic acid into a flask, stir and react at 20° C. for 5 h, distill under reduced pressure, wash with methanol, and dry to obtain thioglycolamide polyurethane.

[0025] (4) Add 200 mL of tetrahydrofuran, 10 g of mercaptoacetamide polyurethane, 0.8 g of N,N-dimethylethylaminomaleamic acid, and 6 mg of benzoin dimethyl ether into a flask, place the flask under a 600 W high-pressure mercury lamp for irradiation for 2 h, and control the lamp distance to be 10 cm; distill under reduced pressure, wash with methanol, and dry to obtain a polyurethane polymer dispersant for color paste.

[0026] Example 2

[0027] (1) Add 10 mL of glacial acetic acid, 0.6 g of N,N-dimethylethylenediamine, and 0.75 g of maleic anhydride to a flask, react at 30° C. for 5 h, filter, and vacuum dry. The product is recrystallized from a mixed solution of methanol and ether to obtain N,N-dimethylethylaminomaleamic acid.

[0028] (2) Add 20 mmol of dry polyethylene glycol 2000 and 48 mmol of isophorone diisocyanate into a flask, heat to 70°C, stir and react for 3 h, then add 24 mmol of N-Boc-serinol and 18 mg of dibutyltin dilaurate, react for 1.5 h, cool, add 300 mL of dichloromethane and 120 mL of trifluoroacetic acid, stir and react for 4 h, distill under reduced pressure, wash with sodium bicarbonate solution, and dry to obtain amino polyurethane.

[0029] (3) Add 150 mL of N,N-dimethylformamide, 10 g of amino polyurethane, 1.02 g of N-hydroxysuccinimide, 1.7 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 0.8 g of thioglycolic acid into a flask, stir and react at 35° C. for 3 h, distill under reduced pressure, wash with methanol, and dry to obtain thioglycolamide polyurethane.

[0030] (4) Add 250 mL of tetrahydrofuran, 10 g of mercaptoacetamide polyurethane, 1.1 g of N,N-dimethylethylaminomaleamic acid, and 10 mg of benzoin dimethyl ether into a flask, place the flask under a 400 W high-pressure mercury lamp for irradiation for 3 h, and control the lamp distance to be 15 cm; distill under reduced pressure, wash with methanol, and dry to obtain a polyurethane polymer dispersant for color paste.

[0031] Example 3

[0032] (1) Add 10 mL of glacial acetic acid, 0.6 g of N,N-dimethylethylenediamine, and 0.84 g of maleic anhydride to a flask, react at 40° C. for 3 h, filter, and vacuum dry. The product is recrystallized from a mixed solution of methanol and ether to obtain N,N-dimethylethylaminomaleamic acid.

[0033] (2) Add 20 mmol of dry polyethylene glycol 2000 and 44 mmol of hexamethylene diisocyanate into a flask, heat to 80°C, stir and react for 2 h, then add 20 mmol of N-Boc-serinol and 15 mg of dibutyltin dilaurate, react for 1.5 h, cool, add 300 mL of dichloromethane and 120 mL of trifluoroacetic acid, stir and react for 4 h, distill under reduced pressure, wash with sodium bicarbonate solution, and dry to obtain amino polyurethane.

[0034] (3) Add 150 mL of N,N-dimethylformamide, 10 g of amino polyurethane, 1.16 g of N-hydroxysuccinimide, 1.9 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 0.9 g of thioglycolic acid into a flask, stir and react at 25° C. for 5 h, distill under reduced pressure, wash with methanol, and dry to obtain thioglycolamide polyurethane.

[0035] (4) Add 250 mL of tetrahydrofuran, 10 g of mercaptoacetamide polyurethane, 1.4 g of N,N-dimethylethylaminomaleamic acid, and 10 mg of benzoin dimethyl ether into a flask, place the flask under a 600 W high-pressure mercury lamp for irradiation for 2 h, and control the lamp distance to be 10 cm; perform vacuum distillation, wash with methanol, and dry to obtain a polyurethane polymer dispersant for color paste.

[0036] Comparative Example 1

[0037] (1) Add 20 mmol of dry polyethylene glycol 2000 and 46 mmol of isophorone diisocyanate to a flask, heat to 70°C, stir and react for 3 h, then add 22 mmol of 2,2-dihydroxymethylpropionic acid and 15 mg of dibutyltin dilaurate and react for 1 h to obtain a carboxyl polyurethane as a dispersant.

[0038] Comparative Example 2

[0039] (1) Add 20 mmol of dry polyethylene glycol 2000 and 46 mmol of isophorone diisocyanate into a flask, heat to 70°C, stir and react for 3 h, then add 22 mmol of N-Boc-serinol and 15 mg of dibutyltin dilaurate, react for 1 h, cool, add 300 mL of dichloromethane and 120 mL of trifluoroacetic acid, stir and react for 6 h, distill under reduced pressure, wash with sodium bicarbonate solution, and dry to obtain amino polyurethane as a dispersant.

[0040] Comparative Example 3

[0041] (1) Add 8 mL of glacial acetic acid, 0.6 g of N,N-dimethylethylenediamine, and 0.75 g of maleic anhydride to a flask, react at 35° C. for 5 h, filter, and vacuum dry. The product is recrystallized from a mixed solution of methanol and ether to obtain N,N-dimethylethylaminomaleamic acid.

[0042] (2) Add 20 mmol of dry polyethylene glycol 2000 and 46 mmol of isophorone diisocyanate into a flask, heat to 70°C, stir and react for 3 h, then add 22 mmol of N-Boc-serinol and 15 mg of dibutyltin dilaurate, react for 1 h, cool, add 300 mL of dichloromethane and 120 mL of trifluoroacetic acid, stir and react for 6 h, distill under reduced pressure, wash with sodium bicarbonate solution, and dry to obtain amino polyurethane.

[0043] (3) Add 100 mL of N,N-dimethylformamide, 10 g of amino polyurethane, 0.75 g of N-hydroxysuccinimide, 1.3 g of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and 0.6 g of thioglycolic acid into a flask, stir and react at 20° C. for 5 h, distill under reduced pressure, wash with methanol, and dry to obtain thioglycolamide polyurethane as a dispersant.

[0044] Add 30 g of phthalocyanine blue and 3 g of dispersant to 100 mL of water, place in a disperser and disperse for 30 minutes to obtain a color paste.

[0045] Blank control: Add 30 g of phthalocyanine blue to 100 mL of water and disperse in a disperser for 30 min to obtain a blank control color paste.

[0046] The color paste was diluted 1000 times, and the average particle size of the pigment was measured using a nanoparticle size Zeta potential instrument.

[0047] The color paste was diluted 4000 times, the supernatant was placed in a quartz colorimetric tube, and the absorbance A at 600 nm was measured using a UV-visible spectrometer. 0 The supernatant was centrifuged in a centrifuge for 15 min at a speed of 3000 r / min; then placed in a quartz colorimetric tube and the absorbance A at 600 nm was measured using a UV-visible spectrometer. t . Calculate the centrifugal stability Q; Q = A t / A 0 ×100%.

[0048] Table 1 Average particle size and centrifugal stability of color paste

[0049] Average particle size (nm) Centrifugal stability Q(%) Example 1 386.7 49.8 Example 2 429.6 48.7 Example 3 393.5 52.0 Comparative Example 1 484.5 44.9 Comparative Example 2 613.1 33.7 Comparative Example 3 675.3 31.2 Blank control 829.6 23.4

[0050] As can be seen from the above table, the blank control is the phthalocyanine blue slurry without adding a dispersant, with an average particle size of 829.6 nm and a centrifugal stability of only 23.4%, indicating poor dispersibility.

[0051] The polyurethane polymer dispersants of Examples 1-3 contain tertiary amine anchoring groups, which can interact with pigments such as phthalocyanine blue, enhance the adsorption of the dispersant on the surface of the phthalocyanine blue pigment, and the dispersant contains carboxyl and amide bond hydrophilic groups, which make the dispersant have good hydrophilicity and water solubility. When the dispersant is adsorbed on the surface of the pigment molecules, a complete adsorption layer is formed, forming a strong hydrophilic effect and steric hindrance effect, preventing the aggregation of the pigment molecules, reducing the particle size of the pigment molecules, thereby improving the dispersibility of the pigments such as phthalocyanine blue. At the same time, it shows good centrifugal stability.

[0052] In Comparative Example 1, 2,2-dihydroxymethylpropionic acid is used as a chain extender. The obtained polyurethane dispersant does not contain a tertiary amine anchoring group, and has a low adsorption effect on the surface of phthalocyanine blue, which causes phthalocyanine blue to easily aggregate, the average particle size of the pigment molecules is large, and the dispersibility and centrifugal stability are poor.

[0053] Comparative Example 2 uses amino polyurethane as a dispersant. Comparative Example 3 uses mercaptoacetamide polyurethane as a dispersant. Both do not contain tertiary amine anchoring groups and carboxyl hydrophilic groups, resulting in low adsorption of the dispersant on the surface of phthalocyanine blue, poor hydrophilicity and water solubility, large average particle size of pigment molecules, and poor dispersibility and centrifugal stability.

[0054] 30 g of phthalocyanine blue and 4-7 g of a dispersant (prepared in Example 1) were added to 100 mL of water, and the mixture was dispersed in a disperser for 30 min to obtain a color paste.

[0055] The average particle size and centrifugal stability of the color paste pigment were tested according to the above method.

[0056] Table 2 Color paste average particle size and centrifugal stability test

[0057] Dispersant dosage (g) Average particle size (nm) Centrifugal stability Q(%) 4 219.0 57.7 5 171.5 71.4 6 122.6 80.3 7 160.7 85.8

[0058] It can be seen from the above table that when the dosage of the dispersant is 6g, the average particle size of the phthalocyanine blue pigment in the color paste is as low as 122.6nm, and when the dosage is 7g, the centrifugal stability is the best, reaching 85.8%.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a polyurethane polymer dispersant for color paste, characterized in that: The preparation method comprises the following steps: Step (1), adding dry polyethylene glycol and diisocyanate to a flask, heating to 70-80° C., stirring and reacting for 2-3 hours, then adding N-Boc-serinol and dibutyltin dilaurate, reacting for 1-1.5 hours, cooling, adding dichloromethane and trifluoroacetic acid, stirring and reacting for 4-6 hours, distilling under reduced pressure, washing, and drying to obtain amino polyurethane; Step (2), adding N,N-dimethylformamide, amino polyurethane, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and thioglycolic acid into a flask, stirring to react, distilling under reduced pressure, washing, and drying to obtain thioglycolamide polyurethane; Step (3), adding tetrahydrofuran, mercaptoacetamide polyurethane, N,N-dimethylethylaminomaleamic acid, and benzoin dimethyl ether into a flask, placing the flask under a high-pressure mercury lamp for irradiation for 2-3 hours, distilling under reduced pressure, washing, and drying to obtain a polyurethane polymer dispersant for color paste.

2. The method for preparing a polyurethane polymer dispersant for color paste according to claim 1, characterized in that: In the step (1), the molar ratio of polyethylene glycol, diisocyanate and N-Boc-serinol is 1:(2.2-2.4):(1-1.2).

3. The method for preparing a polyurethane polymer dispersant for color paste according to claim 2, characterized in that: The diisocyanate is isophorone diisocyanate or hexamethylene diisocyanate.

4. The method for preparing a polyurethane polymer dispersant for color paste according to claim 1, characterized in that: In the step (2), the mass ratio of amino polyurethane, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride, and thioglycolic acid is 100:(7.5-11.6):(13-19):(6-9).

5. The method for preparing a polyurethane polymer dispersant for color paste according to claim 1, characterized in that: In the step (2), the reaction is carried out at 20-35°C for 3-5 hours.

6. The method for preparing a polyurethane polymer dispersant for color paste according to claim 1, characterized in that: In the step (3), the mass ratio of mercaptoacetamide polyurethane, N,N-dimethylethylaminomaleamic acid, and benzoin dimethyl ether is 100:(8-14):(0.06-0.1).

7. The method for preparing a polyurethane polymer dispersant for color paste according to claim 1, characterized in that: In the step (3), the power of the high pressure mercury lamp is 400-600W, and the lamp distance is 10-15cm.

8. The method for preparing a polyurethane polymer dispersant for color paste according to claim 1, characterized in that: The preparation method of N,N-dimethylethylaminomaleamic acid is as follows: glacial acetic acid, N,N-dimethylethylenediamine and maleic anhydride are added into a flask, reacted at 30-40° C. for 3-5 hours, filtered, vacuum dried and recrystallized to obtain N,N-dimethylethylaminomaleamic acid.

9. The method for preparing a polyurethane polymer dispersant for color paste according to claim 8, characterized in that: The mass ratio of the N,N-dimethylethylenediamine to maleic anhydride is 100:(125-140).

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