CN116284611A

CN116284611A - N-heterocyclic compound grafted lignosulfonate and preparation method and application thereof

Info

Publication number: CN116284611A
Application number: CN202310194185.3A
Authority: CN
Inventors: 周明松; 孙宇; 杨蓉; 杨东杰; 邱学青
Original assignee: South China University of Technology SCUT
Current assignee: South China University of Technology SCUT
Priority date: 2023-03-01
Filing date: 2023-03-01
Publication date: 2023-06-23

Abstract

The invention discloses an N-heterocyclic compound grafted lignosulfonate and a preparation method and application thereof. The formula comprises the following components in parts by weight: 10 to 50 parts of lignin, 2 to 8 parts of alkali, 10 to 20 parts of epoxy vinyl monomer, 10 to 30 parts of N-heterocyclic compound monomer containing vinyl, 0.5 to 1.5 parts of initiator and 70 to 250 parts of deionized water. The method comprises the steps of preparing a precursor containing an N-heterocyclic compound, then utilizing epoxy groups of the precursor to carry out nucleophilic substitution reaction with hydroxyl groups in lignin molecules in an alkaline medium, and grafting the precursor into the lignin molecules to prepare the N-heterocyclic compound grafted lignin sulfonate. The N-heterocyclic compound grafted lignosulfonate prepared by the invention contains 0.5-2.0 mmol/g N-heterocyclic compound, and can be used as an efficient dispersing agent to be applied to the field of inorganic nano pigment color paste.

Description

N-heterocyclic compound grafted lignosulfonate and preparation method and application thereof

Technical Field

The invention belongs to the field of natural polymer materials, and particularly relates to an N-heterocyclic compound grafted lignin sulfonate, and a preparation method and application thereof.

Background

The inorganic pigment is colored inorganic compound particles, has poor compatibility with resin, and is dispersed in various media in a particle state when in use. Pigment particles are adsorbed on the surface of a substance or dispersed in the middle of the substance by virtue of a base material to realize the functions of coloring, decoration and the like. The pigment has the properties of covering power, tinting strength, heat resistance, light stability and the like, is a main component for manufacturing paint, ink and other products needing coloring, and plays an important role in the performance of the products.

The particle diameter of the inorganic pigment is very small and is generally below 100 mu m, but with the development of scientific technology and the market demand, pigment powder is developed towards the ultra-fine direction and even can reach below 1 mu m, so that the surface energy of pigment particles is very high, agglomeration is easy to occur among the particles, the dispersibility, the tinting strength and the hiding power are influenced, the service performance of the pigment is directly influenced, a pigment dispersing agent is added to adsorb on the surface of the pigment particles, the pigment particles are dispersed and stabilized through electrostatic repulsion and steric hindrance provided by the dispersing agent, and the problems of pigment particle size enlargement, tinting strength and stability reduction and the like caused by pigment particle agglomeration are prevented.

Traditional pigment dispersants are classified into inorganic dispersants and organic small-molecule dispersants, and mainly play an effective role in dispersion and stabilization through an electrostatic repulsion stabilization mechanism. However, they are not as strong in adsorption on the pigment particle surface and are easily detached from the pigment surface, resulting in re-flocculation or agglomeration of the pigment particles. In recent years, the polymer dispersant is also called hyperdispersant, and by providing high steric hindrance effect, an effective dispersion stable state is formed among pigment particles, and the sensitivity of the system to temperature, pH value and the like is low, so that the polymer dispersant is an ideal dispersant. Currently, commercial polymer dispersants mainly include Solsperse series from ICI, U.S. Daniel, disperse-AYD series from Daniel, germany, disperse BYK series from Pick, hyersol series from Danish KVK, and NBZ-3 in China. Although they exhibit good dispersion, their raw materials are derived from non-renewable fossil-based raw materials, which do not conform to the green sustainable development strategy today. Therefore, the preparation of efficient and green hyper-dispersants by taking renewable biomass resources as raw materials becomes a research hotspot in the pigment industry.

Lignin is the most abundant renewable aromatic polymer on earth with reserves next to cellulose. Compared with other biomass molecules, lignin molecules have a plurality of carboxyl groups, hydroxyl groups, benzene rings and the like, can be used as anchoring groups, and can form tight adsorption on the surface of the pigment through Van der Waals force, hydrogen bonds, pi-pi bonds and the like; secondly, the special three-dimensional network structure of lignin molecules can provide stronger steric hindrance effect, and can effectively prevent pigment from secondary aggregation; in addition, the polyphenol structure and aromatic skeleton in lignin molecule can endow pigment with good ultraviolet oxidation resistance. Therefore, the preparation of the efficient green biomass-based hyper-dispersant by taking the industrial lignin as the raw material has wide market prospect.

The invention develops a novel functional lignin dispersing agent and a synthesis process thereof, wherein epoxy vinyl monomers and vinyl-containing N-heterocyclic compound monomers are used for copolymerization to obtain a precursor, and then the precursor reacts with lignin solution under the condition of high temperature and alkalinity to obtain the N-heterocyclic compound grafted lignin sulfonate. The dispersant is used for preparing the water-based inorganic pigment nano color paste, and D of the color paste ₉₀ The particle size is reduced to below 350nm, and the color paste has no obvious layering and precipitation phenomenon after heat storage for 7 days at 60 ℃, D ₉₀ The grain size is increased to less than 15%, and the heat storage stability is good.

Disclosure of Invention

The invention aims to overcome the defects and shortcomings of the prior art, and provides N-heterocyclic compound grafted lignin sulfonate which has good grinding assisting effect and dispersion stability on inorganic pigment particles, and the prepared water-based ceramic ink can be applied to the ink-jet printing and ceramic surface decoration industries.

The invention improves the hydrophilicity of lignin and the adsorption performance of inorganic pigment particles through modifying lignin, so that the lignin is used as a high-efficiency dispersing agent for preparing inorganic nano pigment color paste. Specifically, an epoxy vinyl monomer and a vinyl-containing N-heterocyclic compound monomer are copolymerized to obtain a precursor, and then the precursor and hydroxyl in lignin molecules undergo nucleophilic substitution reaction under alkaline conditions to obtain the N-heterocyclic compound grafted lignin sulfonate.

The invention also aims to provide a preparation method of the N-heterocyclic compound grafted lignin sulfonate.

It is still another object of the present invention to provide the use of the above-mentioned N-heterocyclic compound grafted lignin sulfonate.

The aim of the invention is achieved by the following technical scheme:

the preparation method of the N-heterocyclic compound grafted lignosulfonate comprises the following steps:

(1) According to the parts by weight, 10 to 20 parts of epoxy vinyl monomer, 10 to 30 parts of N-heterocyclic compound monomer containing vinyl and 40 to 100 parts of water are stirred and dissolved uniformly to obtain a solution, and 0.5 to 1.5 parts of initiator is added into the solution in a dropwise manner to react to obtain the precursor.

(2) Mixing 10-50 parts of lignin and 30-150 parts of water uniformly in parts by mass, heating, adding 2-8 parts of alkali, stirring and dissolving uniformly to obtain lignin aqueous solution, adding the precursor solution prepared in the step (1), stirring and mixing uniformly, and reacting to obtain the N-heterocyclic compound grafted lignin sulfonate.

The epoxy vinyl monomer in the step (1) is at least one of glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether and 1, 2-epoxy-5-ethylene.

The N-heterocyclic compound monomer in the step (1) is at least one of N-vinylimidazole, N-vinylcaprolactam, N-vinylcarbazole, N-vinyldiphenylimine, 2-vinylpyridine, 2-vinylpyrazine, 4-vinylpyridine, 2-vinylquinoline and 5-vinylthiazole.

The initiator in the step (1) is at least one of ammonium persulfate, potassium persulfate, azodiisobutyronitrile, azodiisoheptonitrile and dimethyl azodiisobutyrate.

The dripping is completed within 20-40 min in the step (1); preferably 40min.

The dripping in the step (1) is carried out in a protective atmosphere; preferably dropwise under the protection of nitrogen atmosphere.

The reaction condition in the step (1) is that the reaction is carried out for 1 to 3 hours at the temperature of between 60 and 80 ℃.

The lignin in the step (2) is at least one of sodium lignin sulfonate, potassium lignin sulfonate, ammonium lignin sulfonate, calcium lignin sulfonate and sulfomethylated lignin.

The temperature rising condition in the step (2) is heating to 70-90 ℃.

The reaction condition in the step (2) is 70-95 ℃ for 1-4 hours.

The alkali in the step (2) is at least one of sodium hydroxide and potassium hydroxide.

The N-heterocyclic compound grafted lignin sulfonate is prepared by the preparation method.

The content of the N-heterocyclic compound grafted lignin sulfonate is 0.5-2.0 mmol/g.

The application of the N-heterocyclic compound grafted lignin sulfonate in preparing a dispersing agent.

The N-heterocyclic compound grafted lignosulfonate is applied to preparing inorganic nano pigment color paste as a dispersing agent.

Compared with the prior art, the invention has the following advantages and effects:

1. the invention synthesizes a functional lignin dispersing agent, and introduces N-heterocyclic compound with complexation adsorption function into lignin molecules, thereby greatly improving the adsorption strength to the surface of inorganic pigment. The method is characterized in that inorganic pigment is used as a raw material, and the aqueous inorganic nano pigment color paste is produced in an aqueous medium through a grinding process.

2. The N-heterocyclic compound grafted lignin sulfonate can be used as an adsorption group to carry out high-strength complexation adsorption with the surfaces of inorganic pigment particles. So that the molecules of the dispersing agent are anchored on the surfaces of pigment particles and are not desorbed in the collision of high-frequency Brownian motion; the anionic sulfonic acid group of the dispersant brings negative charge to the surface of pigment particles, so that the particles do not agglomerate and settle in collision. In addition, the three-dimensional structure of lignin has larger steric hindrance, so that pigment particles are prevented from agglomerating.

3. The N-heterocyclic compound grafted lignin sulfonate can be used as a dispersing agent to prepare inorganic nano pigment color paste in an aqueous medium through a grinding process. The prepared inorganic nano pigment color paste has good grinding efficiency and heat storage stability, D ₉₀ Particle size of less than 350nm and D after heat storage at 60deg.C for 7 days ₉₀ The grain diameter is increased to be lower than 15%, water is not separated out, precipitation is not caused, and the comprehensive performance meets the performance requirement of the inorganic nano pigment color paste.

4. The invention uses lignin as main raw material, and the prepared dispersing agent is environment-friendly.

Drawings

FIG. 1 is an infrared spectrum of vinylimidazole grafted lignin sulfonate D1 obtained in example 1.

FIG. 2 is a graph showing the potential of an aqueous solution at various pH values without adding a dispersant and after adding the dispersant obtained in example 1.

FIG. 3 is a Scanning Electron Microscope (SEM) image of a pigment after grinding without adding a dispersant and adding the dispersants obtained in examples 1 to 3 for cadmium red pigment; wherein (a) is a control group to which no dispersant was added, (b) is an experimental group to which D1 was added, (c) is an experimental group to which D2 was added, and (D) is an experimental group to which D3 was added.

Detailed Description

The present invention will be described in further detail with reference to examples and drawings, but embodiments of the present invention are not limited thereto.

Unless specific test conditions are noted in the following embodiments, conventional test conditions or test conditions recommended by the reagent company are generally followed. The materials, reagents and the like used are those obtained commercially unless otherwise specified.

Example 1

(1) 16.0g of allyl glycidyl ether, 30.0. 30.0g N-vinyl imidazole and 100.0g of deionized water are added into a four-necked flask, the mixture is stirred uniformly, and 0.7g of initiator azodiisobutyronitrile is added dropwise into the solution under the protection of nitrogen for 40min to complete the dropwise addition. And after the initiator is added dropwise, reacting at a constant temperature of 80 ℃ for 1 hour to obtain a precursor.

(2) 30.0g of sodium lignin sulfonate and 100.0g of deionized water are added into a four-necked flask, then the temperature is raised to 90 ℃, 4.0g of sodium hydroxide is added, and stirring and dissolving are carried out uniformly, thus obtaining lignin aqueous solution. And (3) adding the precursor obtained in the step (1), stirring and mixing uniformly, and reacting for 4 hours at the temperature of 95 ℃ to obtain the vinylimidazole grafted lignosulfonate.

The vinylimidazole grafted lignin sulfonate obtained in this example 1 was designated as D1, and the content of vinylimidazole groups in D1 was 1.92mmol/g.

Example 2

(1) 12.0g of allyl glycidyl ether, 11.0. 11.0g N-vinyl caprolactam and 40.0g of deionized water are added into a four-necked flask, the mixture is stirred uniformly, 0.5g of initiator ammonium persulfate is added dropwise into the solution under the protection of nitrogen, and the dropwise addition is completed for 20 min. And after the initiator is added dropwise, reacting at a constant temperature of 60 ℃ for 1 hour to obtain a precursor.

(2) 25.0g of potassium lignin sulfonate and 30.0g of deionized water are added into a four-necked flask, then the temperature is raised to 70 ℃, 3.5g of sodium hydroxide is added, and stirring and dissolving are carried out uniformly, thus obtaining lignin aqueous solution. And (3) adding the precursor obtained in the step (1), stirring and mixing uniformly, and reacting at 70 ℃ for 1.5 hours to obtain the vinyl caprolactam grafted lignin sulfonate.

The vinylcaprolactam grafted lignosulfonate obtained in this example 2 was designated as D2, and the content of vinylcaprolactam groups in D2 was 0.57mmol/g.

Example 3

(1) 15.0g of glycidyl methacrylate, 20.0g of 2-vinylpyridine and 70.0g of deionized water are added into a four-necked flask, the mixture is stirred uniformly, 1.0g of initiator potassium persulfate is added dropwise into the solution under the protection of nitrogen, and the dropwise addition is completed for 30 min. And after the initiator is added dropwise, carrying out constant temperature reaction at 70 ℃ for 1.2 hours to obtain a precursor.

(2) 35.0g of sodium lignin sulfonate and 95.0g of deionized water are added into a four-necked flask, then the temperature is raised to 70 ℃, 4.5g of sodium hydroxide is added, and stirring and dissolving are carried out uniformly, thus obtaining lignin aqueous solution. And (3) adding the precursor obtained in the step (1), stirring and mixing uniformly, and reacting for 3 hours at 80 ℃ to obtain the vinyl pyridine grafted lignosulfonate.

The vinylpyridine-grafted lignosulfonate obtained in this example 3 was designated as D3, and the content of vinylpyridine groups in D3 was 1.57mmol/g.

Example 4

(1) 15.0g of 1, 2-epoxy-5-ethylene, 20.0. 20.0g N-vinyl diphenyl imine and 70.0g of deionized water are added into a four-necked flask, the mixture is stirred uniformly to obtain a mixed solution, and 1.0g of initiator azo-diisoheptonitrile is added dropwise into the solution under the protection of nitrogen for 30min to complete the dropwise addition. And after the initiator is added dropwise, reacting at a constant temperature of 70 ℃ for 2 hours to obtain a precursor.

(2) 37.0g of ammonium lignin sulfonate and 75.0g of deionized water are added into a four-necked flask, then the temperature is raised to 70 ℃, 6.5g of sodium hydroxide is added, and stirring and dissolving are carried out uniformly, thus obtaining lignin aqueous solution. And (2) adding 25.0g of the precursor obtained in the step (1), stirring and mixing uniformly, and reacting for 3 hours at 80 ℃ to obtain the vinyl diphenyl methylene grafted lignosulfonate.

The content of vinyldiphenylimine group in the vinyldiphenylene grafted lignin sulfonate in this example 4 was 0.84mmol/g.

Example 5

(1) According to the mass portion, 10.0g of glycidyl methacrylate, 10.0. 10.0g N-vinylcarbazole and 40.0g of deionized water are added into a four-necked flask, uniformly stirred and dissolved, 1.5g of initiator dimethyl azodiisobutyrate is dropwise added into the solution under the protection of nitrogen, after the dropwise addition is completed for 40min, the temperature is raised to 80 ℃ for reaction for 1 hour, and a precursor is prepared.

(2) Adding 40.0g of calcium lignosulfonate and 100.0g of deionized water into a four-necked flask, heating to 70 ℃, adding 7.0g of potassium hydroxide, stirring and dissolving uniformly to obtain lignin aqueous solution. And (3) adding the precursor solution prepared in the step (1), stirring and mixing uniformly, and reacting for 4 hours at 95 ℃. And cooling the product to room temperature, and purifying to obtain the vinylcarbazole grafted lignosulfonate.

The content of vinylcarbazole groups in vinylcarbazole-grafted lignosulfonate in this example 5 was 0.50mmol/g.

Example 6

(1) 16.0g of glycidyl acrylate, 20.0g of 2-vinyl pyrazine and 100.0g of deionized water are added into a four-necked flask according to parts by weight, uniformly stirred and dissolved, 1.5g of initiator ammonium persulfate is dropwise added into the solution under the protection of nitrogen, after the dropwise addition is completed for 40min, the temperature is raised to 80 ℃ for 2 hours, and then the precursor is prepared.

(2) According to the parts by weight, 30.0g of sulfomethylated lignin and 90.0g of deionized water are added into a four-neck flask, the temperature is raised to 70 ℃, 4.4g of sodium hydroxide is added, and stirring and dissolving are carried out uniformly, so that lignin aqueous solution is obtained. And (3) adding the precursor solution prepared in the step (1), stirring and mixing uniformly, and reacting for 2 hours at 80 ℃. And cooling the product to room temperature, and purifying to obtain the vinyl pyrazine grafted lignosulfonate.

The content of the vinyl pyrazine group in the vinyl pyrazine grafted lignin sulfonate in this example 6 was 1.25mmol/g.

Example 7

(1) 15.0g of 1, 2-epoxy-5-ethylene, 30.0g of 4-vinyl pyrimidine and 80.0g of deionized water are added into a four-neck flask according to parts by weight, uniformly stirred and dissolved, 1.0g of initiator azodiisobutyronitrile is dropwise added into the solution under the protection of nitrogen, after the dropwise addition is completed for 30min, the temperature is raised to 70 ℃ for 2 hours, and then the precursor is prepared.

(2) Adding 50.0g of sodium lignin sulfonate and 30.0g of deionized water into a four-necked flask according to parts by weight, heating to 70 ℃, adding 8.0g of sodium hydroxide, stirring and dissolving uniformly to obtain lignin aqueous solution. And (3) adding the precursor solution prepared in the step (1), stirring and mixing uniformly, and reacting for 3 hours at 95 ℃. And cooling the product to room temperature, and purifying to obtain the vinyl pyrimidine grafted lignosulfonate.

The content of vinyl pyrimidine groups in the vinyl pyrimidine grafted lignin sulfonate in this example 7 was 1.06mmol/g.

Example 8

(1) According to the parts by weight, 20.0g of allyl glycidyl ether, 25.0g of 2-vinyl quinoline and 100.0g of deionized water are added into a four-necked flask, the mixture is stirred and dissolved uniformly, 1.5g of initiator potassium persulfate is added dropwise into the solution under the protection of nitrogen, after the dropwise addition is completed for 40min, the temperature is raised to 70 ℃ for reaction for 3 hours, and the precursor is prepared.

(2) 36.0g of potassium lignin sulfonate and 30.0g of deionized water are added into a four-necked flask according to parts by weight, the temperature is raised to 80 ℃, 4.8g of potassium hydroxide is added, and stirring and dissolving are carried out uniformly, thus obtaining lignin aqueous solution. And (3) adding the precursor solution prepared in the step (1), stirring and mixing uniformly, and reacting for 4 hours at the temperature of 85 ℃. And cooling the product to room temperature, and purifying to obtain the vinyl quinoline grafted lignosulfonate.

The content of vinyl quinoline groups in the vinyl quinoline grafted lignin sulfonate in this example 8 was 1.88mmol/g.

Example 9

(1) 15.0g of allyl glycidyl ether, 20.0g of 5-vinyl thiazole and 80.0g of deionized water are added into a four-neck flask according to parts by weight, the mixture is stirred and dissolved uniformly, 1.0g of azo-diisoheptonitrile serving as an initiator is dropwise added into the solution under the protection of nitrogen, after the dropwise addition is completed for 30min, the temperature is raised to 70 ℃ for 2 hours, and then the precursor is prepared.

(2) 10.0g of potassium lignin sulfonate and 90.0g of deionized water are added into a four-necked flask according to the parts by weight, the temperature is raised to 70 ℃, 2.0g of potassium hydroxide is added, and stirring and dissolving are carried out uniformly, so that lignin aqueous solution is obtained. And (3) adding the precursor solution prepared in the step (1), stirring and mixing uniformly, and reacting for 2 hours at 95 ℃. And cooling the product to room temperature, and purifying to obtain the vinyl thiazole grafted lignosulfonate.

The content of vinyl thiazole groups in the vinyl thiazole grafted lignosulfonate of this example 9 was 1.37mmol/g.

Example 10

(1) According to the parts by weight, 20.0g of epoxy vinyl monomer, 30.0. 30.0g N-vinyl caprolactam and 100.0g of deionized water are added into a four-neck flask, uniformly stirred and dissolved, 1.3g of initiator dimethyl azodiisobutyrate is dropwise added into the solution under the protection of nitrogen, after the dropwise addition is completed for 40min, the temperature is raised to 80 ℃ for reaction for 1 hour, and a precursor is prepared.

(2) 26.0g of ammonium lignin sulfonate and 50.0g of deionized water are added into a four-necked flask according to parts by weight, the temperature is raised to 90 ℃, 5.2g of potassium hydroxide is added, and stirring and dissolving are carried out uniformly, so that lignin aqueous solution is obtained. And (3) adding the precursor solution prepared in the step (1), stirring and mixing uniformly, and reacting for 2 hours at 90 ℃. And cooling the product to room temperature, and purifying to obtain the vinyl caprolactam grafted lignosulfonate.

The vinyl caprolactam group content in the vinyl caprolactam grafted lignosulfonate of this example 10 was 1.42mmol/g.

Example 11

(1) 14.0g of glycidyl acrylate, 28.0. 28.0g N-vinyl imidazole and 70.0g of deionized water are added into a four-neck flask according to parts by weight, stirred and dissolved uniformly, 0.8g of initiator potassium persulfate is added into the solution dropwise under the protection of nitrogen, after the dropwise addition is completed for 20min, the temperature is raised to 60 ℃ for reaction for 1.4 hours, and then the precursor is prepared.

(2) Adding 22.0g of sodium lignin sulfonate and 60.0g of deionized water into a four-necked flask according to parts by weight, heating to 70 ℃, adding 3.5g of sodium hydroxide, stirring and dissolving uniformly to obtain lignin aqueous solution. And (3) adding the precursor solution prepared in the step (1), stirring and mixing uniformly, and reacting for 3 hours at 85 ℃. And cooling the product to room temperature, and purifying to obtain the vinylimidazole grafted lignosulfonate.

The content of vinylimidazole groups in the vinylimidazole grafted lignin sulfonate in this example 11 was 2.00mmol/g.

Example 12

(1) According to the mass portion, 20.0g of 1, 2-epoxy-5-ethylene, 20.0g of 4-vinyl pyrimidine and 80.0g of deionized water are added into a four-neck flask, uniformly stirred and dissolved, 1.0g of initiator azodiisobutyronitrile is dropwise added into the solution under the protection of nitrogen, after the dropwise addition is completed for 30min, the temperature is raised to 70 ℃ for 2 hours, and then the precursor is prepared.

(2) 50.0g of potassium lignin sulfonate and 150.0g of deionized water are added into a four-necked flask according to parts by weight, the temperature is raised to 90 ℃, 6.0g of potassium hydroxide is added, and stirring and dissolving are carried out uniformly, so that lignin aqueous solution is obtained. And (3) adding the precursor solution prepared in the step (1), stirring and mixing uniformly, and reacting for 1 hour at 95 ℃. And cooling the product to room temperature, and purifying to obtain the vinyl pyrimidine grafted lignosulfonate.

The content of vinyl pyrimidine groups in the vinyl pyrimidine grafted lignin sulfonate in this example 12 was 0.95mmol/g.

The purified product D1 obtained in the reaction of example 1 was subjected to infrared spectroscopic analysis while sodium lignin Sulfonate (SL) was used as a control, and the results are shown in FIG. 1. As can be seen from FIG. 1, 2940cm ^-1 Is the stretching vibration peak of C-H on imidazole ring; 1640cm ^-1 The absorption peak of imidazole ring skeleton is positioned; 1350cm ^-1 The position is a telescopic vibration absorption peak of C=N on an imidazole ring; 1120cm ^-1 Is a characteristic absorption peak of a nitrogen-containing five-membered ring; 752. 690cm ^-1 The grafting method belongs to the external deformation vibration of the imidazole ring surface, and proves that the vinyl imidazole group is successfully grafted into lignin molecules. In addition, 1040cm ^-1 The characteristic absorption peak of the sulfonic acid group shows that the product contains more sulfonic acid groups.

Elemental analysis was performed on SL, D1, D2 and D3, and the content of N-heterocyclic groups in D1, D2 and D3 was calculated from the difference in the content of nitrogen (N) element, and the results are shown in table 1.

TABLE 1

As is clear from the data in Table 1, the content of N element in SL was 0.10%, and the contents of N-heterocyclic compound groups in D1, D2 and D3 were 1.92, 0.57 and 1.57mmol/g, respectively, as calculated.

Four common inorganic pigments of cobalt blue (with the original particle size of 4.0 mu m), cadmium red (with the original particle size of 1.8 mu m), cobalt green (with the original particle size of 0.8 mu m) and titanium pigment (with the original particle size of 5.5 mu m) are selected as research objects, D1, D2 and D3 are used as dispersing agents, an inorganic nano pigment color paste with the solid content of 20wt.% is prepared by adopting a water-based grinding method, and the adding amount of the dispersing agents is 10wt.% of the color paste. Zirconia beads with the diameter of 0.3mm are used as grinding media, and the mass ratio of the zirconia beads to the color paste is 3:1. Grinding the nanometer color paste by adopting a planetary ball mill (YXQM-2L, changsha Miqi Instrument Co., ltd.) at 400rpm for 10h; zirconia pick beads with the diameter of 0.3mm are used as grinding materials, and the mass ratio of the pick beads to the color paste is 3:1. The particle size and heat storage stability of the prepared aqueous nano color paste are shown in table 2.

Table 2 shows D of 4 aqueous nanopigment color pastes prepared by grinding with D1, D2, D3 and SL as dispersants, respectively ₉₀ Particle size and D after 7 days of heat storage at 60 DEG C ₉₀ Particle size.

TABLE 2

(D ₉₀ Particle size corresponding to a cumulative particle size distribution of 90% for one sample

As can be seen from Table 2, the grinding of cobalt blue, cadmium red, cobalt green and titanium pigment nano color paste using D1, D2, D3 and SL as the dispersing agent, wherein the grinding of D1, D2 and D3 as the dispersing agent for 10 hours can lead to the D of cobalt blue, cadmium red ₉₀ The particle diameter is reduced to be within 200nm, and the D of cobalt green and titanium dioxide ₉₀ Particle size is reduced to below 350nm, the grinding efficiency of D1 is highest, and then D3 and D2 are used, which has positive correlation with the content of N-heterocyclic groups in the molecule. The grinding efficiency of SL is worst, the particle size of color paste is larger, and the thermal stability is poor.

Heat-storing the ground water-based nano color paste at 60 ℃ for 7 days, and then obtaining D color paste ₉₀ The particle size is increased, but D of the nano color paste prepared by D1 ₉₀ The grain diameter is increased to be within 10%, and D of the nanometer color paste prepared by D2 and D3 is adopted ₉₀ Particle size increaseD of nano color paste prepared by SL is basically within 15 percent ₉₀ The particle size reaches the micron order. This demonstrates that the introduction of the N-heterocyclic group improves the adsorption performance of the dispersant on the pigment surface, and improves the grinding efficiency and the heat-resistant stability.

The cadmium red color paste without dispersant and the cadmium red color paste prepared by grinding with D1, D2 and D3 as dispersants were diluted in an aqueous medium with the aqueous cadmium red nanometer color paste as a study object, and zeta potentials at different pH values were tested, and the results are shown in FIG. 2. As can be seen from fig. 2, compared with the cadmium red paste without the dispersant, the absolute value of zeta potential on the surface of the pigment particles increases under different pH conditions after the dispersants D1, D2 and D3 are added, wherein the absolute value (40-65 mv) at ph=5-10 is maximum, which is greater than the theoretical zeta potential (zeta absolute value is not less than 30 mv) required for the particles to remain stable in aqueous solution, which indicates that the nano pigment particles in the cadmium red nano paste prepared by using D1, D2 and D3 as dispersants can exist stably in aqueous medium.

The aqueous cadmium red nano color paste is used as a research object, and the morphology graph and the particle distribution condition of the nano particles in the cadmium red color paste prepared by grinding cadmium red particles without a dispersing agent and using D1, D2 and D3 as dispersing agents are compared through a scanning electron microscope, and are shown in figure 3. As is clear from the SEM image in FIG. 3, in the cadmium red paste milled without the dispersant, the particle size is relatively large, and is in the order of micrometers, and agglomeration among particles is relatively serious. In the cadmium red color paste prepared by adding the dispersing agent, the particle size of the particles is obviously smaller, the particles are in a nano-scale state basically, and aggregation is less generated, so that the addition of the dispersing agent is beneficial to maintaining the dispersion stability of the color paste.

The above examples are preferred embodiments of the present invention, but the embodiments of the present invention are not limited to the above examples, and any other changes, modifications, substitutions, combinations, and simplifications that do not depart from the spirit and principle of the present invention should be made in the equivalent manner, and the embodiments are included in the protection scope of the present invention.

Claims

1. The preparation method of the N-heterocyclic compound grafted lignosulfonate is characterized by comprising the following steps of:

(1) According to the parts by weight, uniformly stirring and dissolving 10-20 parts of epoxy vinyl monomer, 10-30 parts of N-heterocyclic compound monomer containing vinyl and 40-100 parts of water to obtain a solution, dropwise adding 0.5-1.5 parts of initiator into the solution, and reacting to obtain a precursor;

2. The method of manufacturing according to claim 1, characterized in that:

3. The method of manufacturing according to claim 1, characterized in that:

4. The method of manufacturing according to claim 1, characterized in that:

5. The method of manufacturing according to claim 1, characterized in that:

the dripping is completed within 20-40 min in the step (1);

the dripping in the step (1) is carried out in a protective atmosphere;

6. The method of manufacturing according to claim 1, characterized in that:

7. The method of manufacturing according to claim 1, characterized in that:

the temperature rising condition in the step (2) is that the temperature is raised to 70-90 ℃;

the reaction condition of the step (2) is 70-95 ℃ for 1-4 hours;

8. The N-heterocyclic compound grafted lignin sulfonate prepared by the preparation method according to any one of claims 1 to 7.

9. Use of the N-heterocyclic compound grafted lignosulfonate according to claim 8 in the preparation of a dispersant.

10. The use of the N-heterocyclic compound grafted lignin sulfonate according to claim 8 as a dispersant for preparing inorganic nanopigment color paste.