Preparation method of dispersing agent for resin-free color paste

Abstract

The invention relates to the technical field of dispersing agents, and discloses a preparation method of a dispersing agent for resin-free color paste.The preparation method comprises the steps that malonyl chloride and 5-hydroxyisophthalaldehyde are subjected to a reaction, and a tetraaldehyde compound is obtained; the preparation method comprises the following steps: carrying out a reaction with N, N-dimethylglycine, then reacting with single amino-terminated polyethylene glycol, and finally reacting with N, N-dimethylglycine to obtain the dispersant for the resin-free color paste. The dispersant contains a plurality of organic amine anchoring groups of tertiary amines and imino groups, has relatively strong intermolecular force with pigments such as phthalocyanine blue, can be well adsorbed on the surfaces of the pigments, and contains a hydrophilic multi-arm polyethylene glycol molecular chain, so that the dispersion is more uniform and more uniform. A strong hydrophilic effect and a steric hindrance effect are formed on the surface of the pigment, dispersion and aggregation of the pigment are remarkably inhibited, so that the particle size of the pigment is reduced, sedimentation occurs due to overlarge surface particle size, and the pigment shows good dispersity in water and has good centrifugal stability.

Description

Technical Field

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

[0002] Pigments and color pastes are common fillers, widely used in coatings, inks and other fields. Traditional pigments such as phthalocyanine blue have poor dispersibility in water-based coatings and other systems, and are easy to aggregate, affecting the apparent properties of coatings and inks. Therefore, it is necessary to add dispersants to improve the dispersibility of pigments and color pastes. Resin-free color pastes have the advantages of high versatility and wide application range. Its dispersants mainly include hyperbranched dispersants, block polymer dispersants, polyethylene glycol dispersants, etc.

[0003] Polyethylene glycol is cheap and easy to obtain, has good water solubility, and is widely used in dispersants such as pigments and nanomaterials. The invention patent with publication number CN116536060A discloses that ethyl polyethylene glycol, tert-butyl polyethylene glycol, and naphthyl polyethylene glycol are used as raw materials for aqueous dispersants, which can be adsorbed on the surface of pigment particles through different anchoring groups, and then through steric hindrance groups, the pigment particles can maintain a stable dispersion state. However, this patent requires the compounding of multiple different polyethylene glycol dispersants to show good dispersibility, and the dispersion system is relatively complex. Summary of the invention

[0004] The technical problem solved by the invention is: to provide a method for preparing a dispersant for resin-free color paste, thereby solving the problem that the traditional polyethylene glycol dispersant has poor dispersibility for pigments such as phthalocyanine blue.

[0005] Technical solution: A method for preparing a dispersant for resin-free color paste, comprising the following steps:

[0006] Step (1), adding ethanol, a tetraaldehyde compound in a ratio of 1 mol: (6.4-8) mol: (15-22) mL, single-terminated amino polyethylene glycol, and glacial acetic acid into a reaction container, performing a Schiff base reaction, adding an aqueous sodium hydroxide solution to adjust the pH to neutral, then adding sodium borohydride to perform a reduction reaction, adding a saturated sodium chloride solution and dichloromethane, extracting and separating, drying the organic phase to remove water, distilling under reduced pressure, adding the product into petroleum ether to precipitate, filtering, and drying to obtain an intermediate A.

[0007] The tetraaldehyde compound has the following structural formula (I):

[0008] a is any integer value between 2 and 8.

[0009] Step (2), adding N,N-dimethylformamide, intermediate A in a ratio of 1 mol:(4.8-6.4) mol:(0.5-0.6) mol:(4.8-6.4) mol, N,N-dimethylglycine, 4-dimethylaminopyridine (DMAP), 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride (EDC 1) into a reaction container, adding water and dichloromethane after the reaction, extracting and separating, drying the organic phase to remove water, distilling under reduced pressure, adding the product into petroleum ether to precipitate, filtering, and drying to obtain a dispersant for resin-free color paste.

[0010] Preferably, in step (1), the Schiff base reaction is carried out at 35-50° C. for 12-18 h.

[0011] Preferably, in step (1), the reduction reaction is carried out at 20-30° C. for 3-5 h.

[0012] Preferably, in step (2), the reaction is carried out at 20-30° C. for 8-12 h.

[0013] Preferably, the preparation method of the tetraaldehyde compound is as follows: under an ice bath, dichloromethane, a diacyl chloride compound in a ratio of 1 mol:(2-2.4) mol:(2-2.2) mol, 5-hydroxyisophthalaldehyde, and triethylamine are added to a reaction container, followed by reacting at 15-30° C. for 12-18 hours, distilling under reduced pressure, washing with water, and recrystallizing the product with ethanol to obtain a tetraaldehyde compound.

[0014] Preferably, the structural formula of the diacyl chloride compound is a is any integer value between 2 and 8.

[0015] The technical effect of the present invention is as follows: the present invention reacts malonyl chloride with 5-hydroxyisophthalaldehyde to obtain a tetraaldehyde compound; then the tetraaldehyde compound is subjected to Schiff base reaction and reduction reaction with single-terminated amino polyethylene glycol to obtain an intermediate A; finally, the terminal hydroxyl group thereof is subjected to an esterification reaction with N,N-dimethylglycine to obtain a dispersant for resin-free color paste.

[0016] The dispersant prepared by the invention contains organic amine anchoring groups of multiple tertiary amines and imino groups, has strong intermolecular forces with pigments such as phthalocyanine blue, and can make the dispersant adsorbed well on the surface of the pigment. In addition, the dispersant contains hydrophilic multi-arm polyethylene glycol molecular chains, which form strong hydrophilic effects and steric hindrance effects on the surface of the pigment, significantly inhibit the dispersion and aggregation of the pigment, thereby reducing the particle size of the pigment. The surface particle size is too large and sedimentation occurs, and the dispersant exhibits good dispersibility in water and has good centrifugal stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1It is the reaction formula for preparing tetraaldehyde compounds.

[0018] Figure 2 This is the reaction formula for the dispersant used in resin-free color paste. DETAILED DESCRIPTION

[0019] In order to better understand the technical solution of the present invention, the above content of the present invention is further described in detail below through specific implementation methods in the form of embodiments, but this should not be understood as the scope of the above subject matter of the present invention being limited to the following examples. All technologies realized based on the above content of the present invention belong to the scope of the present invention.

[0020] According to the journal "Guangdong Chemical Industry", Issue 10, 2022; Volume 49, Issue 468, the method of the document "Synthesis of Single-Ended Amino Polyethylene Glycol and Study on Its Bionic Modification to Enhance the Anti-pollution of Ultrafiltration Membrane" was used to prepare single-ended amino polyethylene glycol: Under an ice bath, add 100 mL of tetrahydrofuran, polyethylene glycol 600 (control the molar concentration of 5 mmol / L), phthalimide (control the molar concentration of 10 mmol / L), and triphenylphosphine (control the molar concentration of 10 mmol / L) to the reaction vessel, stir for 1 hour, then add diethyl azodicarboxylate (control the molar concentration of 10 mmol / L), stir for 1 hour, and react at 25°C for 12 hours. Add the solution to 100 mL of ethanol, slowly add 2 mL of hydrazine hydrate, let stand at room temperature for 2 hours, add chloroform to extract, and distill under reduced pressure to obtain single-ended amino polyethylene glycol. The structural formula is

[0021] Example 1

[0022] (1) In an ice bath, add 50 mL of dichloromethane, 15 mmol of malonyl chloride, 36 mmol of 5-hydroxyisophthalaldehyde, and 33 mmol of triethylamine to a reaction vessel, and then react at 20°C for 18 h. Distill under reduced pressure, wash with water, and recrystallize the product with ethanol to obtain a tetraaldehyde compound.

[0023] (2) Add 400 mL of ethanol, 10 mmol of a tetraaldehyde compound, 64 mmol of single-terminated amino polyethylene glycol, and 0.15 mL of glacial acetic acid to a reaction vessel, perform a Schiff base reaction at 40° C. for 18 h, add an aqueous sodium hydroxide solution to adjust the pH to neutral, then add 60 mmol of sodium borohydride, perform a reduction reaction at 25° C. for 5 h, add a saturated sodium chloride solution and dichloromethane, extract and separate, dry the organic phase to remove water, and distill under reduced pressure. Add the product to petroleum ether to precipitate, filter, and dry to obtain intermediate A.

[0024] (3) Add 600 mL of N,N-dimethylformamide, 10 mmol of intermediate A, 52 mmol of N,N-dimethylglycine, 5 mmol of 4-dimethylaminopyridine, and 52 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride into a reaction container, and react at 20° C. for 12 h. Add water and dichloromethane. After extraction and separation, dry the organic phase to remove water, distill under reduced pressure, add the product into petroleum ether to precipitate, filter, and dry to obtain a dispersant for resin-free color paste.

[0025] Example 2

[0026] (1) In an ice bath, add 50 mL of dichloromethane, 15 mmol of glutaryl chloride, 30 mmol of 5-hydroxyisophthalaldehyde, and 33 mmol of triethylamine to a reaction vessel, and then react at 15°C for 18 hours. Distill under reduced pressure, wash with water, and recrystallize the product with ethanol to obtain a tetraaldehyde compound.

[0027] (2) Add 500 mL of ethanol, 10 mmol of a tetraaldehyde compound, 80 mmol of single-terminated amino polyethylene glycol, and 0.22 mL of glacial acetic acid to a reaction vessel, perform a Schiff base reaction at 35° C. for 18 h, add an aqueous sodium hydroxide solution to adjust the pH to neutral, then add 64 mmol of sodium borohydride, perform a reduction reaction at 20° C. for 5 h, add a saturated sodium chloride solution and dichloromethane, extract and separate, dry the organic phase to remove water, and distill under reduced pressure. Add the product to petroleum ether to precipitate, filter, and dry to obtain intermediate A.

[0028] (3) Add 600 mL of N,N-dimethylformamide, 10 mmol of intermediate A, 64 mmol of N,N-dimethylglycine, 6 mmol of 4-dimethylaminopyridine, and 64 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride into a reaction container, and react at 25° C. for 12 hours. Add water and dichloromethane, extract and separate, dry the organic phase to remove water, and distill under reduced pressure. Add the product into petroleum ether to precipitate, filter, and dry to obtain a dispersant for resin-free color paste.

[0029] Example 3

[0030] (1) In an ice bath, add 50 mL of dichloromethane, 15 mmol of suberyl chloride, 30 mmol of 5-hydroxyisophthalaldehyde, and 30 mmol of triethylamine into a reaction vessel, and then react at 30°C for 12 h. Distill under reduced pressure, wash with water, and recrystallize the product with ethanol to obtain a tetraaldehyde compound.

[0031] (2) Add 400 mL of ethanol, 10 mmol of a tetraaldehyde compound, 72 mmol of single-terminated amino polyethylene glycol, and 0.15 mL of glacial acetic acid to a reaction vessel, perform a Schiff base reaction at 50° C. for 12 h, add an aqueous sodium hydroxide solution to adjust the pH to neutral, then add 64 mmol of sodium borohydride, perform a reduction reaction at 30° C. for 3 h, add a saturated sodium chloride solution and dichloromethane, extract and separate, dry the organic phase to remove water, and distill under reduced pressure. Add the product to petroleum ether to precipitate, filter, and dry to obtain intermediate A.

[0032] (3) Add 500 mL of N,N-dimethylformamide, 10 mmol of intermediate A, 48 mmol of N,N-dimethylglycine, 5 mmol of 4-dimethylaminopyridine, and 48 mmol of 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride into a reaction container, and react at 30° C. for 8 h. Add water and dichloromethane. After extraction and separation, dry the organic phase to remove water, distill under reduced pressure, add the product into petroleum ether to precipitate, filter, and dry to obtain a dispersant for resin-free color paste.

[0033] In Comparative Example 1, polyethylene glycol 600 was used as the dispersant.

[0034] In Comparative Example 2, single-terminated amino polyethylene glycol was used as a dispersant.

[0035] In Comparative Example 3, Intermediate A (prepared according to the method of Example 1) was used as the dispersant.

[0036] 30 mL of water, 20 g of phthalocyanine blue, and 1.5-4 g of a dispersant (the dispersant described in the above examples and comparative examples) were added to a container, and after stirring, the color paste was placed in a grinder and ground for 2 h, and the material was discharged to obtain a color paste.

[0037] Add 30 mL of water and 20 g of phthalocyanine blue into a container, stir, and grind the color paste in a grinder for 1 hour to obtain the color paste as a blank control.

[0038] The color paste was diluted 1000 times, and the average particle size of the pigment was measured using a nanoparticle size Zeta potential instrument.

[0039] Dilute the color paste 4000 times, take the supernatant and place it in a quartz colorimetric tube, and use a UV-visible spectrometer to measure the absorbance A0 at an absorption wavelength of 600nm. Centrifuge the supernatant in a centrifuge for 15min at a speed of 3000r / min; then place it in a quartz colorimetric tube, and use a UV-visible spectrometer to measure the absorbance A0 at an absorption wavelength of 600nm. t . Calculate the centrifugal stability Q; Q = A t / A0×100%. The test results are shown in Table 1.

[0040] Table 1 Average particle size and centrifugal stability of phthalocyanine blue slurry

[0041]

[0042] It can be seen from the above table that, compared with the blank control, the phthalocyanine blue slurry of Examples 1-3 is added with a polyethylene glycol-based dispersant having a star-shaped multi-arm molecular chain, which contains an organic amine anchoring group of multiple tertiary amines and imino groups, and has a strong intermolecular force with pigments such as phthalocyanine blue, so that the dispersant can be well adsorbed on the surface of the pigment, and the dispersant contains a hydrophilic multi-arm polyethylene glycol molecular chain, which forms a strong hydrophilic effect and steric hindrance effect on the surface of the pigment, significantly inhibiting the dispersion and aggregation of the pigment, thereby reducing the particle size of the pigment, and the surface particle size is too large to settle, showing good dispersibility in water, and having good centrifugal stability.

[0043] Comparative Example 1 uses polyethylene glycol 600 as a dispersant. Comparative Example 2 uses single-terminated amino polyethylene glycol as a dispersant. The intermolecular force between the phthalocyanine blue and the phthalocyanine blue is low, and the phthalocyanine blue does not contain a star-shaped multi-arm molecular chain structure, resulting in poor dispersibility, resulting in a large particle size of the phthalocyanine blue, poor dispersibility, and poor centrifugal stability.

[0044] In Comparative Example 3, intermediate A is used as a dispersant. The end group of the multi-arm polyethylene glycol does not contain a tertiary amine anchoring group. The intermolecular force between the intermediate A and phthalocyanine blue causes the dispersants of each embodiment to have a larger particle size of phthalocyanine blue, and poor dispersibility and centrifugal stability.

[0045] Although the above describes the specific implementation methods of the present invention, it does not limit the scope of protection of the present invention. Based on the technical solution of the present invention, various modifications or variations that can be made by those skilled in the art without creative work are still within the scope of protection of the present invention.

Claims

1. A method for preparing a dispersant for resin-free color paste, characterized in that: The preparation method comprises: Step (1), adding ethanol, a tetraaldehyde compound, a single-terminated amino polyethylene glycol, and glacial acetic acid into a reaction container, performing a Schiff base reaction, adding an aqueous sodium hydroxide solution to adjust the pH to neutral, then adding sodium borohydride to perform a reduction reaction, extracting and separating, adding the product into petroleum ether to precipitate, filtering, and drying to obtain an intermediate A; The tetraaldehyde compound has the structural formula (I) as follows: a is any integer value between 2 and 8; Step (2), adding N,N-dimethylformamide, intermediate A, N,N-dimethylglycine, 4-dimethylaminopyridine, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride into a reaction container, extracting and separating after the reaction, adding the product into petroleum ether to precipitate, filtering, and drying to obtain a dispersant for resin-free color paste.

2. The method for preparing a dispersant for resin-free color paste according to claim 1, characterized in that: In the step (1), the ratio of the tetraaldehyde compound, the single-terminated amino polyethylene glycol, and the glacial acetic acid is 1 mol: (6.4-8) mol: (15-22) mL.

3. The method for preparing a dispersant for resin-free color paste according to claim 1, characterized in that: In the step (1), the Schiff base reaction is carried out at 35-50° C. for 12-18 hours.

4. The method for preparing a dispersant for resin-free color paste according to claim 1, characterized in that: In the step (1), the reduction reaction is carried out at 20-30° C. for 3-5 hours.

5. The method for preparing a dispersant for resin-free color paste according to claim 1, characterized in that: In the step (2), the ratio of intermediate A, N,N-dimethylglycine, 4-dimethylaminopyridine, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide hydrochloride is 1 mol:(4.8-6.4) mol:(0.5-0.6) mol:(4.8-6.4) mol.

6. The method for preparing a dispersant for resin-free color paste according to claim 1, characterized in that: In the step (2), the reaction is carried out at 20-30° C. for 8-12 hours.

7. The method for preparing a dispersant for resin-free color paste according to claim 1, characterized in that: The preparation method of the tetraaldehyde compound comprises: adding dichloromethane, a diacyl chloride compound, 5-hydroxyisophthalaldehyde and triethylamine into a reaction container under an ice bath, then reacting, distilling under reduced pressure, washing and recrystallizing to obtain the tetraaldehyde compound.

8. The method for preparing a dispersant for resin-free color paste according to claim 7, characterized in that: The ratio of the diacyl chloride compound, 5-hydroxyisophthalaldehyde and triethylamine is 1 mol:(2-2.4) mol:(2-2.2) mol.

9. The method for preparing a dispersant for resin-free color paste according to claim 7, characterized in that: The structural formula of the diacyl chloride compound is a is any integer value between 2 and 8.

10. The method for preparing a dispersant for resin-free color paste according to claim 7, characterized in that: The reaction is carried out at 15-30°C for 12-18 h.

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