Preparation method of lignin-based biomass pigment

Abstract

The invention discloses a lignin-based biomass pigment and a preparation method thereof, and belongs to the technical field of pigment production. The method comprises the following steps: carrying out purification treatment and modification treatment on lignin, mixing and stirring a modified lignin derivative dissolving solution and a dye dissolving solution at a certain temperature, and carrying out centrifugal separation or filtration to obtain the lignin-based biomass pigment. From the perspective of pigment composition, the purified lignin derivative is added into the dye to form ionic bond combination with the soluble dye to generate the pigment, so that active groups such as phenolic hydroxyl groups, alcoholic hydroxyl groups, carbon-based conjugated double bonds and carboxyl groups are introduced into the components, the prepared pigment has high biocompatibility, and the stability of the pigment can be maintained for 500 hours. Meanwhile, the preparation method is simple and high in economic benefit, and has wide application prospects in the aspects of printing ink, ink-jet printing, pigment printing paste coloring and the like.

Description

Technical Field

[0001] The invention relates to the field of pigment production, and in particular to a method for preparing a lignin-based biomass pigment. Background Art

[0002] Pigments are widely used in textile printing due to their complete color spectrum, bright colors, high fastness and non-decomposability. However, traditional pigments are mostly organic and inorganic pigments, which contain harmful substances during the preparation process, causing environmental and health problems. At the same time, the preparation of traditional pigments has high requirements for experimental equipment and preparation methods, and the preparation cost is high. Therefore, the development of biomass pigments has great development prospects.

[0003] Biomass pigments are mainly derived from plants and marine animals in nature, such as madder, gamboge, and purple extracted from shellfish. Since biomass pigments are generally non-toxic and degradable, their development meets the current requirements for environmental protection and sustainable development. At the same time, the production process of biomass pigments can make full use of agricultural and forestry waste to achieve efficient resource utilization and circular economy. Compared with traditional organic pigments, the production cost of biomass pigments is lower, which conforms to the principle of economic benefit. For example, CN202410221475.7 uses poplar as a raw material to prepare printing ink pigments, which effectively improves the fluidity, dispersibility and stability of the ink. At the same time, the durability, stability and printing effect of printing ink pigments are improved. CN 202110237568.5 prepares polyurethane color paste by adding a bio-based dispersant to a carbon dioxide-based polycarbonate polyether polyol and a bio-based soybean oil polyol, stirring evenly and adding pigment powder, which has the advantages of good fluidity and improved production efficiency. Biomass pigments are generally non-toxic and degradable, and their development meets the current requirements for environmental protection and sustainable development. Compared with traditional pigments, biomass pigments and color pastes have the advantages of low cost and high environmental protection.

[0004] Lignin is a complex organic polymer that is widely present in the supporting tissues of vascular plants and certain algae. It is a three-dimensional network biopolymer formed by phenylpropane units connected by ether bonds and carbon-carbon bonds, and contains abundant active groups such as aromatic ring structures, aliphatic and aromatic hydroxyl groups, and quinone groups. This unique chemical structure gives lignin good dispersibility and environmental protection. At present, there have been studies that add lignin derivatives as dispersants to pigment paste components to improve their dispersibility. For example, CN 114685810A obtains carboxyl lignin derivatives as phthalocyanine pigment dispersants through the esterification reaction of acid anhydride and lignin, thereby obtaining a dispersed pigment with a small particle size and a stable dispersion system. However, this method is a pigment post-treatment method, which has poor compatibility with the pigment, resulting in the pigment's dispersion stability performance not lasting. At the same time, there are also studies on the formation of biomass pigments by chemically bonding modified lignin derivatives with dye molecules. For example, IN202421021012A forms a new type of pigment by forming a covalent bond between lignin sulfonate and vinyl sulfone-based reactive dyes through an addition reaction. The pigment has good dispersibility in epoxy polyamine systems. However, since the two are bonded by covalent bonds, the structural stability of the pigment itself is not strong and the pigment does not have good solubility, which limits its application. Summary of the invention

[0005] [Technical issues]

[0006] The problem to be solved by the present invention is that conventional organic pigments or inorganic pigments are usually extremely poor in environmental protection, have high production costs, are not economical, and have poor dispersion stability.

[0007] [Technical solution]

[0008] In order to solve the above problems, the present invention starts with the composition of the pigment, takes advantage of the advantages of lignin such as high biological environmental friendliness and low economic cost, and obtains lignin derivatives such as lignin sulfonate, alkaline lignin and sulfate lignin by modifying the purified lignin, and combines it with a soluble dye by ion bonds, so that phenolic hydroxyl, alcohol hydroxyl, carbonyl conjugated double bond, carboxyl and other active groups are added to its structure to generate insoluble lignin-based biomass pigments. The pigment prepared by this method can have high stability in the water system and its stability can be maintained for a long time, and it has good compatibility with the substrate and high economic benefits.

[0009] The present invention first provides a method for preparing a lignin-based biomass pigment, comprising the following steps:

[0010] (1) purifying lignin, modifying the purified lignin to form a lignin derivative, dissolving the purified lignin in deionized water to form a lignin derivative solution, and dissolving a soluble cationic dye in deionized water to obtain a dye solution;

[0011] (2) mixing and stirring the lignin derivative solution obtained in step (1) and the dye solution;

[0012] (3) Centrifuging or filtering the mixture obtained in step (2) to obtain a lignin-based biomass pigment.

[0013] In one embodiment of the present invention, the purification treatment is to add lignin to deionized water, and at the same time, add 5NNaOH solution to adjust the solution pH to 9-10, stir at 80°C for 2h to obtain a lignin alkaline solution, and then add 2N HCl solution to the solution until the system pH is 2, stand and separate, and obtain purified lignin powder by filtration.

[0014] In one embodiment of the present invention, the monomer structure of the lignin in step (1) is one or more of guaiacyl, syringyl and p-hydroxyphenyl structures.

[0015] In one embodiment of the present invention, the lignin derivative in step (1) is one or more of lignin sulfonate, alkaline lignin and kraft lignin.

[0016] In one embodiment of the present invention, the modification method in step (1) is to add a modifier to the purified lignin at 80°C for stirring reaction, and then centrifuge to obtain a lignin derivative by precipitating. The modifier includes one of sulfite and sulfate.

[0017] In one embodiment of the present invention, the mass concentration of the lignin derivative solution in step (1) is 0.001-2.0 wt.%.

[0018] In one embodiment of the present invention, the soluble cationic dye structure in step (1) is one or more of xanthene, methine, monoazo, triarylmethane, and oxazine basic dyes.

[0019] In one embodiment of the present invention, the mass concentration of the soluble cationic dye solution in step (1) is 0.01 to 1.0 wt.%.

[0020] In one embodiment of the present invention, the molar ratio of the lignin derivative to the dye in step (2) is 1:(0.1-1).

[0021] In one embodiment of the present invention, the mixing method in step (2) is one or both of magnetic stirring or ultrasonic stirring, the stirring time is 10 min to 120 min, and the stirring temperature is 50° C. to 100° C.

[0022] In one embodiment of the present invention, the rotation speed during centrifugation in step (3) is 3000 r / min to 10000 r / min, and the centrifugation time is 15-20 min.

[0023] The present invention also discloses a method for preparing pigment powder, which comprises drying the lignin-based biomass pigment to obtain the lignin-based biomass pigment powder.

[0024] In one embodiment of the present invention, the drying method is spray drying or freeze drying.

[0025] In one embodiment of the present invention, the inlet temperature of the spray drying is 30°C to 100°C, and the outlet temperature is 30°C to 140°C; the temperature of the freeze drying is -10°C to -50°C, the vacuum degree is 1.3-13Pa, and the freezing time is 12-24h.

[0026] The invention also discloses a method for preparing a pigment dispersion liquid. The pigment dispersion liquid is obtained by dispersing the lignin-based biomass pigment in water. The concentration of the pigment dispersion liquid is 1.0 wt.% to 10 wt.%.

[0027] The invention also discloses an application of the lignin-based biomass pigment powder or pigment dispersion in the textile field.

[0028] Beneficial effects:

[0029] (1) A lignin-based biomass pigment is prepared by adding a certain amount of modified lignin derivatives to the pigment composition. The pigment is formed by ionic bonds between a soluble cationic dye and a lignin derivative to form an insoluble pigment, thereby introducing active groups such as phenolic hydroxyl, alcoholic hydroxyl, carbonyl conjugated double bond and carboxyl into the dye component, so that the prepared pigment has the advantages of high biocompatibility and high stability.

[0030] (2) The preparation method of the present invention is simple and economically efficient, and the pigment stability can be maintained for a long time, thereby solving the shortcomings of traditional organic and inorganic pigments, such as causing great pollution to the environment during the production process and poor pigment stability.

[0031] (3) The particle size of the biomass pigment prepared by the method of the present invention is 150 to 330 nm, and has good dispersibility. The dispersion stability time of the pigment is 320 to 500 hours, and the dispersion stability is good. DETAILED DESCRIPTION

[0032] The exemplary embodiments of the present disclosure will be described in more detail below. Although exemplary embodiments of the present disclosure are shown, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to enable the scope of the present disclosure to be fully communicated to those skilled in the art.

[0033] The test method is analyzed as follows:

[0034] (1) Size and particle size distribution:

[0035] The laser particle size analyzer was used to analyze and characterize the pigment particle size and particle size distribution (PDI) of the dispersion.

[0036] (2) Dispersion stability:

[0037] The pigment dispersion is placed in a constant temperature and pressure dark box, and the time when precipitation appears in the dispersion is observed and recorded.

[0038] Example 1

[0039] A method for preparing a lignin-based biomass pigment, the specific steps are as follows:

[0040] Take 5g of lignin and add it to 100mL of deionized water, and add 5N NaOH solution to adjust the system pH to 9-10, heat it to 80℃ and stir for 2h to obtain a lignin alkaline solution, then add 2N HCl solution to it until the system pH is 2, let it stand and separate, and filter to obtain pure lignin powder. Add 1g of sodium sulfite to the purified lignin at 80℃ and continue stirring for 2h. After the reaction is completed, centrifuge at 1500r / min for 15min to obtain sodium lignin sulfonate. Dissolve 1g of sodium lignin sulfonate in 99mL of deionized water to prepare a sodium lignin sulfonate solution with a concentration of 1wt.%. 1 g of basic red was dissolved in 99 g of deionized water to prepare a dye solution with a mass concentration of 1 wt.%, and the dye solution and sodium lignin sulfonate solution were added to a beaker at a volume ratio of 1:1, and magnetically stirred for 60 min at room temperature, wherein the stirring speed was 500 rpm / min; after the reaction was completed, the mixed solution was centrifuged at 8000 r / min, and washed with anhydrous ethanol and water to obtain a lignin-based biomass pigment, which was then freeze-dried at a temperature of -10°C and a vacuum degree of 10 Pa for 48 hours to obtain a lignin-based biomass pigment.

[0041] A method for preparing a pigment dispersion comprises: taking 0.01 g of a lignin-based biomass pigment and ultrasonically dispersing it in 20 mL of deionized water to obtain a pigment dispersion.

[0042] Example 2

[0043] A method for preparing a lignin-based biomass pigment, the specific steps are as follows:

[0044] Take 5g of lignin and add it to 100mL of deionized water with a pH of 9-10, add 5N NaOH solution to adjust the system pH to 9-10, heat to 80℃ and stir for 2h to obtain a lignin alkaline solution, then add 2N HCl solution to the system pH to 2, let stand and stratify, and filter to obtain pure lignin powder. Add 1g of sodium sulfite to the purified lignin at 80℃ and continue stirring for 2h. After the reaction is completed, centrifuge at 1500r / min for 15min to obtain sodium lignin sulfonate. Dissolve 1g of sodium lignin sulfonate in 99mL of deionized water to prepare a sodium lignin sulfonate solution with a concentration of 1wt.%. 1 g of basic yellow dye was dissolved in 99 g of deionized water to prepare a dye solution with a mass concentration of 1 wt.%, and the dye solution and sodium lignin sulfonate solution were added to a beaker at a volume ratio of 1:1, and magnetically stirred for 60 min at room temperature, wherein the stirring speed was 500 rpm / min; after the reaction was completed, the mixed solution was centrifuged at 8000 r / min, and washed with anhydrous ethanol and water to obtain a lignin-based biomass pigment, which was then freeze-dried at a temperature of -10°C and a vacuum degree of 10 Pa for 48 hours to obtain a lignin-based biomass pigment.

[0045] A method for preparing a pigment dispersion comprises: taking 0.01 g of a lignin-based biomass pigment and ultrasonically dispersing it in 20 mL of deionized water to obtain a pigment dispersion.

[0046] Example 3

[0047] A method for preparing a lignin-based biomass pigment, the specific steps are as follows:

[0048] Take 5g of lignin and add it to 100mL of deionized water with a pH of 9-10, add 5N NaOH solution to adjust the system pH to 9-10, heat to 80℃ and stir for 2h to obtain a lignin alkaline solution, then add 2N HCl solution to the system pH to 2, let stand and stratify, and filter to obtain pure lignin powder. Add 1g of sodium sulfite to the purified lignin at 80℃ and continue stirring for 2h. After the reaction is completed, centrifuge at 1500r / min for 15min to obtain sodium lignin sulfonate. Dissolve 1g of sodium lignin sulfonate in 99mL of deionized water to prepare a sodium lignin sulfonate solution with a concentration of 1wt.%. 1 g of basic orange 33 dye was dissolved in 99 g of deionized water to prepare a dye solution with a mass concentration of 1 wt.%, and the dye solution and sodium lignin sulfonate solution were added to a beaker at a volume ratio of 1:1, and magnetically stirred for 60 min at room temperature, wherein the stirring speed was 500 rpm / min; after the reaction was completed, the mixed solution was centrifuged at 8000 r / min, washed with anhydrous ethanol and water to obtain a lignin-based biomass pigment, and then freeze-dried at a temperature of -10°C and a vacuum degree of 10 Pa for 48 hours to obtain a lignin-based biomass pigment.

[0049] A method for preparing a pigment dispersion comprises: taking 0.01 g of a lignin-based biomass pigment and ultrasonically dispersing it in 20 mL of deionized water to obtain a pigment dispersion.

[0050] Example 4

[0051] A method for preparing a lignin-based biomass pigment, the specific steps are as follows:

[0052] Take 5g of lignin and add it to 100mL of deionized water with a pH of 9-10, add 5N NaOH solution to adjust the system pH to 9-10, heat to 80℃ and stir for 2h to obtain a lignin alkaline solution, then add 2N HCl solution to the system pH to 2, let stand and stratify, and filter to obtain pure lignin powder. Add 1g of sodium sulfite to the purified lignin at 80℃ and continue stirring for 2h. After the reaction is completed, centrifuge at 1500r / min for 15min to obtain sodium lignin sulfonate. Dissolve 1g of sodium lignin sulfonate in 99mL of deionized water to prepare a sodium lignin sulfonate solution with a concentration of 1wt.%. 1 g of basic red 5 dye was dissolved in 99 g of deionized water to prepare a dye solution with a mass concentration of 1 wt.%, and the dye solution and sodium lignin sulfonate solution were added to a beaker at a volume ratio of 1:1, and magnetically stirred for 60 minutes at room temperature, wherein the stirring speed was 500 rpm / min; after the reaction was completed, the mixed solution was centrifuged at 8000 r / min, washed with anhydrous ethanol and water to obtain a lignin-based biomass pigment, and then freeze-dried at a temperature of -10°C and a vacuum degree of 10 Pa for 48 hours to obtain a lignin-based biomass pigment.

[0053] A method for preparing a pigment dispersion comprises: taking 0.01 g of a lignin-based biomass pigment and ultrasonically dispersing it in 20 mL of deionized water to obtain a pigment dispersion.

[0054] Example 5

[0055] A method for preparing a lignin-based biomass pigment, the specific steps are as follows:

[0056] Take 5g of lignin and add it to 100mL of deionized water with a pH of 9-10, add 5N NaOH solution to adjust the system pH to 9-10, heat to 80℃ and stir for 2h to obtain a lignin alkaline solution, then add 2N HCl solution to the system pH to 2, let stand and stratify, and filter to obtain pure lignin powder. Add 1g of sodium sulfite to the purified lignin at 80℃ and continue stirring for 2h. After the reaction is completed, centrifuge at 1500r / min for 15min to obtain sodium lignin sulfonate. Dissolve 1g of sodium lignin sulfonate in 99mL of deionized water to prepare a sodium lignin sulfonate solution with a concentration of 1wt.%. 1g of basic blue 45 dye was dissolved in 99g of deionized water to prepare a dye solution with a mass concentration of 1wt.%, and the dye solution and sodium lignin sulfonate solution were added to a beaker at a volume ratio of 1:1, and magnetically stirred for 60min at room temperature, wherein the stirring speed was 500rpm / min; after the reaction, the mixed solution was centrifuged at 8000r / min, washed with anhydrous ethanol and water to obtain a lignin-based biomass pigment, and then freeze-dried at a temperature of -10°C and a vacuum degree of 10Pa for 48h to obtain a lignin-based biomass pigment.

[0057] A method for preparing a pigment dispersion comprises: taking 0.01 g of a lignin-based biomass pigment and ultrasonically dispersing it in 20 mL of deionized water to obtain a pigment dispersion.

[0058] Example 6

[0059] A method for preparing a lignin-based biomass pigment, the specific steps are as follows:

[0060] Take 5g of lignin and add it to 100mL of deionized water with a pH of 9-10, add 5N NaOH solution to adjust the system pH to 9-10, heat to 80℃ and stir for 2h to obtain a lignin alkaline solution, then add 2N HCl solution to the system pH to 2, let stand and stratify, and filter to obtain pure lignin powder. Add 1g of sodium sulfite to the purified lignin at 80℃ and continue stirring for 2h. After the reaction is completed, centrifuge at 1500r / min for 15min to obtain sodium lignin sulfonate. Dissolve 1g of sodium lignin sulfonate in 99mL of deionized water to prepare a sodium lignin sulfonate solution with a concentration of 1wt.%. 1 g of basic black 1 dye was dissolved in 99 g of deionized water to prepare a dye solution with a mass concentration of 1 wt.%, and the dye solution and sodium lignin sulfonate solution were added to a beaker at a volume ratio of 1:1, and magnetically stirred for 60 minutes at room temperature, wherein the stirring speed was 500 rpm / min; after the reaction was completed, the mixed solution was centrifuged at 8000 r / min, washed with anhydrous ethanol and water to obtain a lignin-based biomass pigment, and then freeze-dried at a temperature of -10°C and a vacuum degree of 10 Pa for 48 hours to obtain a lignin-based biomass pigment.

[0061] A method for preparing a pigment dispersion comprises: taking 0.01 g of a lignin-based biomass pigment and ultrasonically dispersing it in 20 mL of deionized water to obtain a pigment dispersion.

[0062] Example 7

[0063] A method for preparing a lignin-based biomass pigment, the specific steps are as follows:

[0064] Take 5g of lignin and add it to 100mL of deionized water with a pH of 9-10, add 5N NaOH solution to adjust the system pH to 9-10, heat to 80℃ and stir for 2h to obtain a lignin alkaline solution, then add 2N HCl solution to the system pH to 2, let stand and stratify, and filter to obtain pure lignin powder. Add 1g of sodium sulfite to the purified lignin at 80℃ and continue stirring for 2h. After the reaction is completed, centrifuge at 1500r / min for 15min to obtain sodium lignin sulfonate. Dissolve 1g of sodium lignin sulfonate in 99mL of deionized water to prepare a sodium lignin sulfonate solution with a concentration of 1wt.%. 1 g of basic red 5 dye was dissolved in 99 g of deionized water to prepare a dye solution with a mass concentration of 1 wt.%, and the dye solution and sodium lignin sulfonate solution were added into a beaker, and magnetic stirring was performed for 60 min at room temperature, wherein the stirring speed was 500 rpm / min; after the reaction was completed, the mixed solution was centrifuged at 8000 r / min, and washed with anhydrous ethanol and water to obtain a lignin-based biomass pigment, which was then freeze-dried at a temperature of -10°C and a vacuum degree of 10 Pa for 48 hours to obtain a lignin-based biomass pigment.

[0065] A method for preparing a pigment dispersion comprises: taking 0.01 g of a lignin-based biomass pigment and ultrasonically dispersing it in 20 mL of deionized water to obtain a pigment dispersion.

[0066] Example 8

[0067] Take 5g of lignin and add it to 100mL of deionized water with a pH of 9-10, add 5N NaOH solution to adjust the system pH to 9-10, heat to 80℃ and stir for 2h to obtain a lignin alkaline solution, then add 2N HCl solution to the system pH to 2, let stand and stratify, and filter to obtain pure lignin powder. Add 1g of sodium sulfate to the purified lignin at 80℃ and continue stirring for 2h. After the reaction is completed, centrifuge at 1500r / min for 15min to obtain sodium sulfate lignin. Dissolve 1g of sodium sulfate lignin in 99mL of deionized water to prepare a sodium sulfate lignin solution with a concentration of 1wt.%. 1 g of alkaline yellow dye was dissolved in 99 g of deionized water to prepare a dye solution with a mass concentration of 1 wt.%, and the dye solution and sodium sulfate lignin solution were added into a beaker, and magnetic stirring was performed for 60 min at room temperature, wherein the stirring speed was 500 rpm / min; after the reaction was completed, the mixed solution was centrifuged at 8000 r / min, and washed with anhydrous ethanol and water to obtain a lignin-based biomass pigment, which was then freeze-dried at a temperature of -10°C and a vacuum degree of 10 Pa for 48 hours to obtain a lignin-based biomass pigment.

[0068] A method for preparing a pigment dispersion comprises: taking 0.01 g of a lignin-based biomass pigment and ultrasonically dispersing it in 20 mL of deionized water to obtain a pigment dispersion.

[0069] Comparative Example 1

[0070] A method for preparing a commercial pigment, the specific steps are as follows:

[0071] 1g of rhodamine B was dissolved in 49g of deionized water to prepare a dye solution with a mass concentration of 2wt.%; 0.4g of sodium tungstate, 0.4g of sodium molybdate and 0.2g of disodium hydrogen phosphate were taken to prepare a precipitant solution with a mass concentration of 1wt.%; the two solutions were mixed in a beaker at a volume ratio of 1:1, and magnetically stirred for 60min at room temperature, wherein the stirring speed was 500rpm / min; after the reaction was completed, the mixed solution was centrifuged at 8000r / min, washed with anhydrous ethanol, and washed with water to obtain a lake pigment, which was then freeze-dried for 48h; 0.01g of the lake pigment was ultrasonically dispersed in 20ml of deionized water to obtain a pigment dispersion.

[0072] Comparative Example 2

[0073] 1g of lignin was dissolved in 50mL of 1% NaOH and stirred for 10 minutes. Then, a bifunctional active dye (0.833mmol) containing vinyl sulfone and triazine groups was added to the lignin solution. The reaction mixture was then stirred at 80-90°C for 8 hours. After 8 hours of reaction, the liquid was cooled to room temperature. HCl was added to make the pH value 4-5. The precipitate was filtered through a suction pump and dried in an oven. Sodium lignin sulfonate was reacted with disperse yellow F3R active dye to obtain a biomass pigment.

[0074] Table 1 shows the particle size, PDI and dispersion stability data of the pigments in Examples 1 to 8 and Comparative Examples 1 to 2. It can be seen from Table 1 that the particle size of the biomass pigment prepared by the method of the present invention is 150 to 330 nm, which has good dispersibility, and the dispersion stability time of the pigment is 320 to 500 hours, which has good dispersion stability. However, the current commercial pigment (Comparative Example 1) not only has a large particle size and poor dispersibility, but also has poor dispersion stability. After the dispersion is placed for 120 hours, precipitation begins to appear. Comparative Example 2 prepares a pigment in which lignin and dye are covalently bonded. This pigment also has the disadvantages of poor dispersibility, large particle size and poor dispersion stability.

[0075] Table 1 Particle size, PDI and dispersion stability data of pigments in Examples 1 to 8 and Comparative Examples 1 to 2

[0076] sample Particle size / nm PDI Dispersion stability / h Example 1 255.4 0.201 389 Example 2 187.6 0.145 422 Example 3 152.1 0.127 498 Example 4 222 0.233 490 Example 5 271.8 0.211 398 Example 6 298.9 0.345 500 Example 7 301.4 0.453 320 Example 8 320.6 0.324 430 Comparative Example 1 1032.5 0.856 120 Comparative Example 2 890.5 0.543 300

[0077] The embodiments provided above are not intended to limit the scope of the present invention, and the steps described are not intended to limit the execution order thereof. Those skilled in the art may make obvious improvements to the present invention in combination with existing common knowledge, which also fall within the scope of protection defined by the claims of the present invention.

Claims

1. A method for preparing a lignin-based biomass pigment, characterized in that: The steps include: (1) purifying lignin, modifying the purified lignin to form a lignin derivative, dissolving the purified lignin in deionized water to form a lignin derivative solution, and dissolving a soluble cationic dye in deionized water to obtain a dye solution; (2) mixing and stirring the lignin derivative solution obtained in step (1) and the dye solution; (3) The mixture obtained in step (2) is centrifuged at a speed of 3000 to 10000 r / min for 15 to 20 min to obtain a lignin-based biomass pigment.

2. The preparation method according to claim 1, characterized in that: The purification treatment is to add lignin to deionized water, and at the same time, add 5N NaOH solution to adjust the solution pH to 9-10, stir at 80°C for 2h to obtain a lignin alkaline solution, then add 2N HCl solution to the solution until the system pH is 2, stand and separate, and obtain purified lignin powder by filtering.

3. The preparation method according to claim 1, characterized in that: The lignin derivative in step (1) is one or more of lignin sulfonate, alkaline lignin and sulfate lignin. The modification method is to add a modifier to the purified lignin at 80°C for stirring reaction, and then centrifuge to obtain a lignin derivative by precipitating. The modifier includes one of sulfite and sulfate.

4. The preparation method according to claim 1, characterized in that: The mass concentration of the lignin derivative solution in step (1) is 0.001-2.0 wt.%.

5. The preparation method according to claim 1, characterized in that: In step (1), the structure of the soluble cationic dye is one or more of xanthene, methine, monoazo, triarylmethane, and oxazine basic dyes, and the mass concentration of the soluble cationic dye solution is 0.01-1.0wt.%.

6. The preparation method according to claim 1, characterized in that: In step (2), the molar ratio of the lignin derivative to the dye is 1:(0.1-1), the mixing method is one or both of magnetic stirring or ultrasonic stirring, the stirring time is 10 to 120 minutes, and the stirring temperature is 50 to 100°C.

7. The lignin-based biomass pigment prepared by the preparation method according to any one of claims 1 to 6.

8. A method for preparing pigment powder, characterized in that: The method comprises drying the lignin-based biomass pigment according to claim 7 to obtain lignin-based biomass pigment powder, wherein the drying method is one of spray drying and freeze drying; the inlet temperature of the spray drying is 30°C to 100°C, and the outlet temperature is 30°C to 140°C; the temperature of the freeze drying is -10°C to -50°C, the vacuum degree is 1.3-13Pa, and the freezing time is 12-24h.

9. A method for preparing a pigment dispersion, comprising dispersing the lignin-based biomass pigment according to claim 7 in water to obtain a pigment dispersion, wherein the mass concentration of the pigment dispersion is 1.0 to 10 wt.%.

10. Use of the lignin-based biomass pigment powder prepared by the method for preparing the lignin-based biomass pigment powder according to claim 8 or the pigment dispersion prepared by the method for preparing the pigment dispersion according to claim 9 in the textile field.