Preparation method and application of nanoscale pigment

Abstract

The invention relates to the technical field of color paste pigments, and discloses a preparation method and application of a nanoscale pigment. Diisocyanate, 2-methylallyl alcohol, diethylenetriamine and the like are subjected to a reaction, and a hyperbranched dispersing agent is obtained; and dispersing and modifying pigments such as carbon black and the like to obtain the nano-scale pigment. The dispersant contains a large amount of tertiary amine, imino and other anchoring groups, forms a strong interaction force with the surface of pigments such as carbon black, contains hyperbranched molecular chains as solvated chains, can extend in a water medium, reduces the agglomeration among carbon black particles and the particle size, and has good dispersion performance. The nanoscale carbon black pigment with better dispersity is obtained. The hyperbranched dispersion contains a carbamate structural unit which is the same as that of polyurethane, the dispersed and modified carbon black has better interfacial compatibility with the polyurethane, and the influence on the mechanical property of the polyurethane is smaller.

Description

Technical Field

[0001] The present invention relates to the technical field of color paste pigments, and specifically to a preparation method and application of nano-level pigments. Background Art

[0002] Pigments mainly include organic pigments, inorganic pigments, etc., such as pigment red, phthalocyanine blue, carbon black, titanium dioxide, etc. Among them, carbon black has good weather resistance and chemical resistance, is cheap and easy to obtain, and is widely used in fields such as coatings and inks. However, the dispersibility of carbon black is poor, and it will agglomerate in solvents such as water. During storage and actual use, phenomena such as flocculation will occur, seriously affecting the performance of materials such as coatings and inks. Therefore, a dispersant needs to be added to prepare a color paste pigment with excellent dispersibility.

[0003] Traditional dispersants mainly include small molecule dispersants, polymer dispersants, hyperdispersants, etc. Introducing anchoring groups such as organic amines and carboxylic acids into the dispersant can improve the interaction force and dispersibility of the dispersant with pigments such as carbon black. Hyperbranched polymers are a new type of functional material and have a wide range of applications in pigment dispersants, lubricants, polymer material additives, etc. Chinese Patent CN115197401B discloses an oil-phase carbon black dispersion liquid including a hyperbranched polymer containing a long-chain alkyl group and a preparation method thereof. Using the hyperbranched polymer containing a long-chain alkyl group as a carbon black dispersant, medium and high pigment carbon black that is difficult to disperse in non-polar solvents can be dispersed with high efficiency, and an oil-phase carbon black dispersion liquid with a high content and low viscosity can be obtained. However, the carbon black dispersion liquid of this patent is an organic solvent and oil-phase system, which is not conducive to the actual application of carbon black in water-based coatings, inks, etc. Summary of the Invention

[0004] (1) Technical problems to be solved:

[0005] In view of the deficiencies of the prior art, the present invention provides a nano-level pigment with good dispersibility and excellent compatibility with water-based polyurethane.

[0006] (2) Technical solution: A preparation method of a nano-level pigment:

[0007] (1) Add a solvent, diisocyanate, 2-methylallyl alcohol, and triethylamine to a flask, heat to 40 - 70 °C, stir and react for 4 - 6 h, remove low-boiling substances by vacuum distillation, and dry to obtain an allyl intermediate.

[0008] (2) Add water, ethanol, the allyl intermediate, and diethylenetriamine to a flask, heat to 50 - 75 °C, stir and react for 8 - 10 h, add diethylenetriamine again, continue to react for 3 - 5 h, heat to volatilize, wash with acetone, and dry to obtain a hyperbranched dispersant.

[0009] (3) Add pigments and hyperbranched dispersants to water, stir and disperse, then perform ball milling in a sand mill, and discharge to obtain nanoscale colorants.

[0010] Preferably, the solvent in (1) is tetrahydrofuran or toluene.

[0011] Preferably, the molar ratio of diisocyanate, 2-methylallyl alcohol, and triethylamine in (1) is 1:(2 - 2.4):(0.016 - 0.024). The diisocyanate is hexamethylene diisocyanate or isophorone diisocyanate.

[0012] Preferably, the molar ratio of allyl intermediate and diethylenetriamine in (2) is 1:(0.9 - 1.2).

[0013] Preferably, the mass ratio of pigment to hyperbranched dispersant in (3) is 100:(1 - 4).

[0014] Preferably, the pigment is ultrafine carbon black.

[0015] Preferably, the rotation speed during ball milling in (3) is 2000 - 3000 r / min, and the time is 1.5 - 3 h.

[0016] Preferably, the nanoscale colorant is applied to waterborne polyurethane.

[0017] (III) Technical effects: In the present invention, an allyl intermediate containing two alkenyl groups and a urethane structure is used as monomer A 2 monomer, and it undergoes a Michael addition reaction with monomer B 3 diethylenetriamine to obtain a hyperbranched dispersant. It contains a large number of anchoring groups such as tertiary amines and imino groups, forming strong interaction forces with the surfaces of pigments such as carbon black, so it can be firmly and tightly adsorbed on the surface of carbon black. At the same time, it contains hyperbranched molecular chains as solvation chains, which can extend in the water medium, thereby reducing the agglomeration between carbon black particles, exhibiting good dispersion performance, significantly reducing the particle size of carbon black pigments, and thus obtaining nanoscale carbon black colorants with better dispersion.

[0018] The hyperbranched dispersant of the present invention contains the same urethane structure unit as polyurethane, enabling the carbon black after dispersion modification to have better interfacial compatibility with polyurethane. At the same time, the carbon black particles in the colorant are evenly dispersed in waterborne polyurethane, having less impact on its mechanical properties, and showing higher tensile strength and elongation at break. Specific embodiments

[0019] The following further elaborates on the present invention with specific embodiments. The present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, these embodiments are provided to make the understanding of the disclosed content of the present invention more thorough and comprehensive.

[0020] Ultra-fine carbon black, model XC 72R, Shanghai Kayin Chemical Co., Ltd.

[0021] Waterborne polyurethane, model 50G80, solid content 33%, Guangdong Xidun New Materials Technology Co., Ltd.

[0022] Example 1:

[0023] (1) Add 8 mL of tetrahydrofuran, 5 mmol of hexamethylene diisocyanate, 10 mmol of 2-methylallyl alcohol, and 0.12 mmol of triethylamine to a flask. Heat to 40 °C and stir for 6 h. Remove low-boiling substances by vacuum distillation, and dry to obtain an allyl intermediate; the reaction formula is:

[0024]

[0025] (2) Add 40 mL of water, 50 mL of ethanol, 10 mmol of allyl intermediate, and 6.6 mmol of diethylenetriamine to a flask equipped with a condenser reflux tube. Heat to 60 °C and stir for 10 h. Then add an additional 4.6 mmol of diethylenetriamine and continue to react for 3 h. Heat to evaporate, wash with acetone, and dry to obtain a hyperbranched dispersant. The reaction principle is:

[0026]

[0027] (3) Add 100 g of ultra-fine carbon black and 1 g of hyperbranched dispersant to 500 mL of water. Stir and disperse for 20 min, then perform ball milling in a sand mill for 2 h at a rotation speed of 2000 r / min and discharge to obtain nano-scale pigment.

[0028] Example 2:

[0029] (1) Add 10 mL of toluene, 5 mmol of isophorone diisocyanate, 12 mmol of 2-methylallyl alcohol, and 0.08 mmol of triethylamine to a flask. Heat to 70 °C and stir for 4 h. Remove low-boiling substances by vacuum distillation, and dry to obtain an allyl intermediate; the reaction formula is:

[0030]

[0031] (2) Add 30 mL of water, 30 mL of ethanol, 10 mmol of allyl intermediate, and 6.6 mmol of diethylenetriamine to a flask equipped with a condenser reflux tube. Heat to 50 °C and stir for 10 h. Then add an additional 2.4 mmol of diethylenetriamine and continue to react for 5 h. Heat to evaporate, wash with acetone, and dry to obtain a hyperbranched dispersant.

[0032] (3) Add 100 g of ultrafine carbon black and 2.5 g of hyperbranched dispersant to 500 mL of water, stir and disperse for 20 min, carry out ball milling in a sand mill for 1.5 h at a rotation speed of 3000 r / min, and discharge to obtain nanoscale colorant.

[0033] Example 3:

[0034] (1) Add 30 mL of water, 40 mL of ethanol, 10 mmol of allyl intermediate (prepared in the same way as in Example 1), and 6.6 mmol of diethylenetriamine to a flask equipped with a condensing reflux tube, heat to 75 °C, stir and react for 8 h, then add an additional 3.6 mmol of diethylenetriamine, continue to react for 3 h, heat to volatilize, wash with acetone, and dry to obtain the hyperbranched dispersant.

[0035] (2) Add 100 g of ultrafine carbon black and 4 g of hyperbranched dispersant to 500 mL of water, stir and disperse for 20 min, carry out ball milling in a sand mill for 3 h at a rotation speed of 1000 r / min, and discharge to obtain nanoscale colorant.

[0036] Comparative Example 1:

[0037] (1) Add 100 g of ultrafine carbon black to 500 mL of water, stir and disperse for 20 min, carry out ball milling in a sand mill for 2 h at a rotation speed of 2000 r / min, and discharge to obtain colorant.

[0038] Comparative Example 2:

[0039] (1) Add 40 mL of water, 50 mL of ethanol, 10 mmol of ethylene glycol dimethacrylate (CAS No. 97-90-5), and 6.6 mmol of diethylenetriamine to a flask equipped with a condensing reflux tube, heat to 60 °C, stir and react for 10 h, then add an additional 4.6 mmol of diethylenetriamine, continue to react for 3 h, heat to volatilize, wash with acetone, and dry to obtain the hyperbranched dispersant.

[0040] (2) Add 100 g of ultrafine carbon black and 1 g of hyperbranched dispersant to 500 mL of water, stir and disperse for 20 min, carry out ball milling in a sand mill for 2 h at a rotation speed of 2000 r / min, and discharge to obtain nanoscale colorant.

[0041] Comparative Example 3:

[0042] (1) Add 40 mL of water, 50 mL of ethanol, 10 mmol of allyl intermediate, and 6.6 mmol of N,N'-dimethylethylenediamine (CAS No. 110-70-3) to a flask equipped with a condensing reflux tube, heat to 60 °C, stir and react for 10 h, then add an additional 4.6 mmol of N,N'-dimethylethylenediamine, continue to react for 3 h, heat to volatilize, wash with acetone, and dry to obtain the dispersant.

[0043] (2) Add 100 g of ultrafine carbon black and 1 g of hyperbranched dispersant to 500 mL of water, stir and disperse for 20 min, perform ball milling in a sand mill for 2 h at a rotation speed of 2000 r / min, and discharge to obtain a colorant.

[0044] Take 1 mL of the colorant, add 1000 mL of water for dilution, stir for 30 min, and test the average particle size through a laser light scattering particle size analyzer.

[0045] Table 1 Average particle size test

[0046]

[0047] Compared with Comparative Example 1, the hyperbranched dispersants in Examples 1-3 contain a large number of anchoring groups such as tertiary amines and imino groups, form strong interaction forces with the surfaces of pigments such as carbon black, and thus are firmly and tightly adsorbed on the surface of carbon black. At the same time, they contain hyperbranched molecular chains as solvation chains, which can stretch in the aqueous medium, thereby reducing the agglomeration between carbon black particles, exhibiting good dispersion performance, and significantly reducing the particle size of carbon black pigments.

[0048] In Comparative Example 2, ethylene glycol dimethacrylate was reacted with diethylenetriamine to obtain a hyperbranched dispersant, which also has good dispersion effect on carbon black.

[0049] In Comparative Example 3, an allyl intermediate and N,N'-dimethylethylenediamine were reacted to obtain a dispersant that does not have a hyperbranched molecular chain and has poor dispersion effect on carbon black with a large particle size.

[0050] Weigh 20 mL of the colorant and add it to 100 mL of aqueous polyurethane emulsion, shear and disperse, and place at room temperature for 30 days to observe the dispersion of the emulsion.

[0051] Shear and disperse the emulsion, pour it into a mold, perform vacuum degassing, bake and cure at 80 °C for 8 h, and cool at room temperature to make a test specimen, and test the tensile properties according to the method of GB / T 19250-2013.

[0052] Table 2

[0053]

[0054]

[0055] After testing, in Comparative Example 1, when carbon black was added to polyurethane, due to the very poor dispersion of carbon black and easy agglomeration, the dispersion of the polyurethane emulsion was very poor, resulting in a large amount of sediment. Moreover, the compatibility between carbon black and polyurethane was poor, and the dispersion in polyurethane was not good and easy to agglomerate, seriously affecting the mechanical properties of polyurethane and reducing the tensile strength and elongation at break.

[0056] The hyperbranched dispersibility of Examples 1-3 contains the same urethane structural unit (-NH-CO-O-) as that of polyurethane, enabling better interfacial compatibility between the carbon black after dispersion modification and polyurethane. Meanwhile, the carbon black is uniformly dispersed in the aqueous polyurethane, with less impact on its mechanical properties, showing relatively high tensile strength and elongation at break.

[0057] The hyperbranched dispersant of Comparative Example 2 does not contain urethane structural units, resulting in poor compatibility between the carbon black after dispersion modification and polyurethane, which has a certain impact on its mechanical properties, leading to lower tensile strength and elongation at break than those of the examples.

[0058] The carbon black pigment of Comparative Example 3 has poor dispersibility and a large particle size, with poor dispersion in polyurethane and easy agglomeration, which has a certain impact on the mechanical properties of polyurethane, leading to lower tensile strength and elongation at break than those of the examples.

Claims

1. A method for preparing a nanoscale pigment, characterized in that: The preparation method is: (1) Add a solvent, diisocyanate, 2-methylallyl alcohol and triethylamine to a flask, stir to react, and then remove low-boiling substances by distillation under reduced pressure, and dry to obtain an allyl intermediate; (2) Add water, ethanol, allyl intermediate and diethylenetriamine to a flask, stir to react, then add diethylenetriamine, continue to react, heat to volatilize, wash with acetone, and dry to obtain a hyperbranched dispersant; (3) Add pigment and hyperbranched dispersant into water, stir and disperse, then ball-mill in a sand mill to obtain nano-scale pigment.

2. The method for preparing the nanoscale pigment according to claim 1, characterized in that: The reaction temperature in (1) is 40-70°C and the reaction time is 4-6h.

3. The method for preparing the nanoscale pigment according to claim 1, characterized in that: The solvent in (1) is tetrahydrofuran or toluene.

4. The method for preparing the nanoscale pigment according to claim 1, characterized in that: The molar ratio of diisocyanate, 2-methylallyl alcohol and triethylamine in (1) is 1:(2-2.4):(0.016-0.024).

5. The method for preparing the nanoscale pigment according to claim 1, characterized in that: The diisocyanate is hexamethylene diisocyanate or isophorone diisocyanate.

6. The method for preparing the nanoscale pigment according to claim 1, characterized in that: The molar ratio of the allyl intermediate to diethylenetriamine in (2) is 1:(0.9-1.2).

7. The method for preparing the nanoscale pigment according to claim 1, characterized in that: The stirring reaction temperature in (2) is 50-75°C for 8-10 hours; the reaction time is 3-5 hours.

8. The method for preparing the nanoscale pigment according to claim 1, characterized in that: The mass ratio of the pigment to the hyperbranched dispersant in (3) is 100:(1-4), and the pigment includes ultrafine carbon black.

9. The method for preparing the nanoscale pigment according to claim 1, characterized in that: The rotation speed during ball milling in (3) is 2000-3000 r / min, and the time is 1.5-3 h.

10. Use of the nanoscale colorant obtained by the preparation method according to any one of claims 1 to 9 in waterborne polyurethane.

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