Environment-friendly dye for papermaking and preparation method thereof

Abstract

The present application belongs to the technical field of papermaking dyes, and particularly relates to an environmentally-friendly dye for papermaking and a preparation method thereof. The sulfonate surfactant is prepared by a two-step method, and has excellent dispersibility, stability and emulsifiability, and good compatibility with basic light yellow O. The sulfonate surfactant is used in combination with the basic light yellow O, so that the solubility, dispersion stability and high-temperature stability of the basic light yellow O dye are significantly improved in the manners of reducing interfacial tension, increasing wettability and improving permeation. When the environmentally-friendly dye prepared by the present application is used for paper dyeing, the dyeing rate and light fastness of the dye can be obviously improved, the uniformity and effect of dyeing can be improved, and the waste of the dye can be effectively reduced, so that the requirement of green development is met.

Description

Technical Field

[0001] This invention belongs to the field of paper dye technology, specifically relating to an environmentally friendly dye for papermaking and its preparation method. Background Technology

[0002] Paper dyes are a class of chemical substances used to color paper. They can increase the color and appearance of paper, improve its transparency and gloss, enhance its water and light resistance, and improve its printability and vibrancy. Paper dyes can be classified into several categories, including natural and synthetic dyes, cationic and anionic dyes, and water-soluble and oil-soluble dyes. Commonly used paper dyes in the paper industry include direct dyes, basic dyes, acid dyes, and sulfur dyes. Direct dyes are widely used due to their ease of use, complete color spectrum, and low price. They are usually dissolved in water and used directly for dyeing, but their solubility is low, and they can only bind to fibers in small amounts. Basic dyes carry a positive charge and have electrostatic attraction to fibers, making them suitable for dyeing unbleached chemical pulp and mechanical pulp. However, because bleached pulp has fewer negatively charged groups, its attraction to dyes is weak, so other methods are needed to increase its retention. Acid dye molecules contain a large number of soluble groups, which affects the further binding of dye molecules to the fiber surface. The paper dye industry plays a vital role in providing a wide range of colored paper products, but it also faces challenges such as environmental pollution and cost. To address these issues, researchers are exploring more environmentally friendly dye preparation methods.

[0003] Patent application number CN201610808217.4 discloses a sodium lignin sulfonate dye dispersant. Using alkaline lignin from papermaking waste liquor as raw material, a series of reactions yields a low-fouling sodium lignin sulfonate dye dispersant product. Compared with existing processes, this invention not only significantly reduces the amount of blocking agents such as epichlorohydrin and oxidants such as hydrogen peroxide, but also lowers the reaction temperature and pressure, while greatly reducing production costs and reaction time. It achieves the effect of simultaneously blocking phenolic hydroxyl groups and reducing fouling. Furthermore, the lignin prepared by this invention... Sodium sulfonate dispersant has good heat resistance and staining properties; Patent application number CN201810888653.6 provides a pearlescent dye for papermaking. The raw material formulation of this dye is scientific. After kaolin is modified by a coupling agent, double bonds are introduced on the surface, which can improve the dispersibility of kaolin with other raw materials. It solves the problems of severe aggregation between pigment particles, difficulty in dispersion, and easy agglomeration, and enhances the smoothness, decorative effect and gloss of the paper, making the paper surface smooth and delicate, with good hand feel, good stability and not easy to fade. All of the above inventions use sodium lignosulfonate as a surfactant. Sodium lignosulfonate is an anionic surfactant with strong dispersing ability. Its molecular structure contains various active groups, such as sulfonic acid groups, hydroxyl groups, and carboxyl groups. These groups enable sodium lignosulfonate to adsorb onto the surface of various solid particles. In paper dyes, it is mainly used as a dye dispersant to improve the solubility and uniformity of dyes and enhance the dyeing effect. However, sodium lignosulfonate also has its limitations, such as its darker color may affect the whiteness of paper, and its dispersion persistence is relatively poor. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this invention is to provide an environmentally friendly dye for papermaking, which has excellent comprehensive performance and meets the requirements of green development; this invention also provides a method for preparing the environmentally friendly dye for papermaking.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0006] An environmentally friendly dye for papermaking includes an alkaline dye and a dispersing agent, wherein the dispersing agent is a sulfonate surfactant; the preparation method of the sulfonate surfactant is as follows:

[0007] Step S1: Under stirring conditions at a temperature of 55-65℃, sodium hydroxyethyl sulfonate is dispersed in dimethyl sulfoxide. After mixing evenly, 4-bromocrotonic acid and p-toluenesulfonic acid are added sequentially. The reaction is carried out for 5-8 hours, the pH is adjusted to 7, and the mixture is cooled to room temperature. After purification, the intermediate is obtained.

[0008] Step S2: Under stirring conditions at a temperature of 60-70℃, 4-amino-N,N-dimethylaniline is dispersed in 2-methyltetrahydrofuran. After mixing evenly, the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride are added in sequence. The reaction is carried out for 6-10 hours, cooled to room temperature, and purified to obtain a sulfonate surfactant.

[0009] The synthetic route for sulfonate surfactants is as follows:

[0010]

[0011] This invention uses sodium hydroxyethyl sulfonate and 4-bromocrotonic acid as starting materials, and esterifies them under the catalysis of p-toluenesulfonic acid to obtain an intermediate; then, using the intermediate and 4-amino-N,N-dimethylaniline as raw materials, an N-alkylation reaction is carried out under the catalysis of sodium hydroxide and benzyltriethylammonium chloride to obtain a sulfonate surfactant; this sulfonate surfactant has excellent dispersibility, stability and emulsifying properties.

[0012] To obtain the sulfonate surfactant and ensure product consistency, the molar ratio of sodium hydroxyethyl sulfonate, 4-bromocrotonic acid, and p-toluenesulfonic acid in step S1 is 1:1.0-1.2:0.04-0.07, and the mass-to-volume ratio of sodium hydroxyethyl sulfonate to dimethyl sulfoxide is 0.19-0.25 g / mL; the molar ratio of 4-amino-N,N-dimethylaniline, the intermediate, sodium hydroxide, and benzyltriethylammonium chloride in step S2 is 1:2.1-2.4:1.0-1.2:0.08-0.11, and the mass-to-volume ratio of 4-amino-N,N-dimethylaniline to 2-methyltetrahydrofuran is 0.22-0.26 g / mL.

[0013] Furthermore, the basic dye is Basic Yellow O.

[0014] Basic Yellow O is a professional paper dye widely used in the papermaking industry. It is a yellow powder dye with good suspension properties and vibrant color, making it suitable for applications requiring yellow pigments in paper. During the papermaking process, when Basic Yellow O is added to the pulp fibers for dispersion, it helps stabilize dye molecules, improving the dispersion and uniformity of the dye in the paper products, thereby enhancing the paper's smoothness and strength. Furthermore, Basic Yellow O's good suspension properties can further improve the smoothness and strength of paper products. Therefore, Basic Yellow O is widely used in the papermaking industry and is an important paper dye. However, Basic Yellow O has poor solubility in cold water, meaning that its molecular structure is not easily unfolded or dispersed in cold water, resulting in low stability. Basic Yellow O has good solubility in hot water, producing a bright yellow color, but it decomposes upon boiling, indicating its instability at high temperatures. Therefore, the storage and transportation requirements for Basic Yellow O are quite stringent. Furthermore, Basic Yellow O has poor lightfastness, easily fading under light, affecting the durability of dyed items. Additionally, the wastewater from Basic Yellow O dye has high color intensity, is difficult to degrade, and easily pollutes the environment.

[0015] The present invention also provides a method for preparing an environmentally friendly dye for papermaking, comprising the following steps: mixing an alkaline dye, a dispersing agent, and deionized water evenly and then grinding them for 5-7 hours at a grinding speed of 1800-2000 r / min, thereby obtaining the dye.

[0016] Furthermore, the mass ratio of the alkaline dye, dispersing agent, and deionized water is 1:0.9-1.1:15-20; the grinding media is made of zirconia beads with a size of 0.2-0.5 mm.

[0017] The present invention has the following beneficial effects:

[0018] This invention prepares a sulfonate surfactant through a sequential esterification and N-alkylation reaction. The sulfonate surfactant molecule contains N,N-dimethylamine, acrylate, and sodium sulfonate structures, exhibiting excellent dispersibility, stability, and emulsifying properties. The sulfonate surfactant provided by this invention has good compatibility with Basic Yellow O. When used in combination with Basic Yellow O, it not only significantly improves the solubility and dispersion stability of Basic Yellow O in cold water but also enhances its high-temperature stability, thereby significantly improving the stability and safety of the dye during storage and transportation. Furthermore, the sulfonate surfactant can further improve the dispersion of Basic Yellow O dye by reducing interfacial tension, increasing wettability, and enhancing penetration, thereby improving the dye's rheological properties and compatibility with fibers. This increases the dye uptake and lightfastness, making it easier for the dye to adhere evenly to the fiber, improving dyeing uniformity and effect, effectively reducing dye waste, lowering production costs, and minimizing environmental impact. Detailed Implementation

[0019] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application. The raw materials used in the following embodiments are all common commercially available products.

[0020] Example 1

[0021] A method for preparing a sulfonate surfactant includes the following steps:

[0022] Step S1: Under stirring conditions at 60℃, sodium hydroxyethyl sulfonate was dispersed in dimethyl sulfoxide. After mixing evenly, 4-bromocrotonic acid and p-toluenesulfonic acid were added sequentially. The reaction was carried out for 7 hours, the pH was adjusted to 7, and the mixture was cooled to room temperature. The mixture was filtered, and the filtrate was collected. Dimethyl sulfoxide was removed by vacuum distillation. Deionized water and ethyl acetate were added for extraction. The aqueous phase was concentrated and dried under vacuum at 60℃ for 24 hours to obtain the intermediate. The molar ratio of sodium hydroxyethyl sulfonate, 4-bromocrotonic acid, and p-toluenesulfonic acid was 1:1.1:0.06, the mass-to-volume ratio of sodium hydroxyethyl sulfonate to dimethyl sulfoxide was 0.23 g / mL, and the volume ratio of deionized water to ethyl acetate was 6:1.

[0023] Step S2: Under stirring conditions at 65℃, 4-amino-N,N-dimethylaniline was dispersed in 2-methyltetrahydrofuran. After mixing evenly, the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride were added sequentially. The reaction was carried out for 8 hours, cooled to room temperature, filtered, and the filtrate was collected. 2-methyltetrahydrofuran was removed by vacuum distillation. Deionized water and ethyl acetate were then added for extraction. The aqueous phase was concentrated and dried under vacuum at 60℃ for 24 hours to obtain a sulfonate surfactant. The molar ratio of 4-amino-N,N-dimethylaniline, intermediate, sodium hydroxide, and benzyltriethylammonium chloride was 1:2.3:1.1:0.09, the mass-to-volume ratio of 4-amino-N,N-dimethylaniline to 2-methyltetrahydrofuran was 0.24 g / mL, and the volume ratio of deionized water to ethyl acetate was 6:1.

[0024] The NMR results for the modified silane coupling agent are as follows: 1 H NMR (300MHz, DMSO-d6) δ7.01 (t, 2H), 6.62 (s, 4H), 5.97 (d, 2H), 4.59 (t, 4H), 4.02 (d, 4H), 3.02 (s, 6H), 2.75 (t, 4H).

[0025] A method for preparing an environmentally friendly dye for papermaking includes the following steps: mixing an alkaline dye, a dispersing agent, and deionized water evenly and then grinding them for 6 hours at a speed of 1900 r / min to obtain a bright yellow clear solution. The mass ratio of the alkaline dye, dispersing agent, and deionized water is 1:1:18. The dispersing agent is a sulfonate surfactant, the alkaline dye is alkaline yellow O, and the grinding medium is zirconia beads with sizes of 0.2 mm and 0.5 mm (equal masses of the two sizes of zirconia beads are mixed). The mass ratio of the alkaline dye to the zirconia beads is 1:20.

[0026] Example 2

[0027] A method for preparing a sulfonate surfactant includes the following steps:

[0028] Step S1: Under stirring conditions at 55℃, sodium hydroxyethyl sulfonate was dispersed in dimethyl sulfoxide. After mixing evenly, 4-bromocrotonic acid and p-toluenesulfonic acid were added sequentially. The reaction was carried out for 8 hours, the pH was adjusted to 7, and the mixture was cooled to room temperature. The mixture was filtered, and the filtrate was collected. Dimethyl sulfoxide was removed by vacuum distillation. Deionized water and ethyl acetate were added for extraction. The aqueous phase was concentrated and dried under vacuum at 60℃ for 24 hours to obtain the intermediate. The molar ratio of sodium hydroxyethyl sulfonate, 4-bromocrotonic acid, and p-toluenesulfonic acid was 1:1.2:0.07, the mass-to-volume ratio of sodium hydroxyethyl sulfonate to dimethyl sulfoxide was 0.19 g / mL, and the volume ratio of deionized water to ethyl acetate was 6:1.

[0029] Step S2: Under stirring conditions at 60℃, 4-amino-N,N-dimethylaniline was dispersed in 2-methyltetrahydrofuran. After mixing evenly, the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride were added sequentially. The reaction was carried out for 10 hours, cooled to room temperature, filtered, and the filtrate was collected. 2-methyltetrahydrofuran was removed by vacuum distillation. Deionized water and ethyl acetate were then added for extraction. The aqueous phase was concentrated and dried under vacuum at 60℃ for 24 hours to obtain a sulfonate surfactant. The molar ratio of 4-amino-N,N-dimethylaniline, intermediate, sodium hydroxide, and benzyltriethylammonium chloride was 1:2.4:1.2:0.11, the mass-to-volume ratio of 4-amino-N,N-dimethylaniline to 2-methyltetrahydrofuran was 0.22 g / mL, and the volume ratio of deionized water to ethyl acetate was 6:1.

[0030] A method for preparing an environmentally friendly dye for papermaking includes the following steps: mixing an alkaline dye, a dispersing agent, and deionized water evenly and then grinding them for 7 hours at a speed of 1800 r / min to obtain a bright yellow clear solution. The mass ratio of the alkaline dye, dispersing agent, and deionized water is 1:1.1:20. The dispersing agent is a sulfonate surfactant, the alkaline dye is Alkaline Yellow O, and the grinding medium is zirconia beads with sizes of 0.2 mm and 0.5 mm (equal masses of the two sizes of zirconia beads are mixed). The mass ratio of the alkaline dye to the zirconia beads is 1:20.

[0031] Example 3

[0032] A method for preparing a sulfonate surfactant includes the following steps:

[0033] Step S1: Under stirring conditions at 65℃, sodium hydroxyethyl sulfonate was dispersed in dimethyl sulfoxide. After mixing evenly, 4-bromocrotonic acid and p-toluenesulfonic acid were added sequentially. The reaction was carried out for 5 hours, the pH was adjusted to 7, and the mixture was cooled to room temperature. The mixture was filtered, and the filtrate was collected. Dimethyl sulfoxide was removed by vacuum distillation. Deionized water and ethyl acetate were added for extraction. The aqueous phase was collected and concentrated. The mixture was then vacuum dried at 60℃ for 24 hours to obtain the intermediate. The molar ratio of sodium hydroxyethyl sulfonate, 4-bromocrotonic acid, and p-toluenesulfonic acid was 1:1:0.04, the mass-to-volume ratio of sodium hydroxyethyl sulfonate to dimethyl sulfoxide was 0.25 g / mL, and the volume ratio of deionized water to ethyl acetate was 6:1.

[0034] Step S2: Under stirring conditions at 70℃, 4-amino-N,N-dimethylaniline was dispersed in 2-methyltetrahydrofuran. After mixing evenly, the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride were added sequentially. The reaction was carried out for 6 hours, cooled to room temperature, filtered, and the filtrate was collected. 2-methyltetrahydrofuran was removed by vacuum distillation. Deionized water and ethyl acetate were then added for extraction. The aqueous phase was concentrated and dried under vacuum at 60℃ for 24 hours to obtain a sulfonate surfactant. The molar ratio of 4-amino-N,N-dimethylaniline, intermediate, sodium hydroxide, and benzyltriethylammonium chloride was 1:2.1:1:0.08, the mass-to-volume ratio of 4-amino-N,N-dimethylaniline to 2-methyltetrahydrofuran was 0.26 g / mL, and the volume ratio of deionized water to ethyl acetate was 6:1.

[0035] A method for preparing an environmentally friendly dye for papermaking includes the following steps: mixing an alkaline dye, a dispersing agent, and deionized water evenly and then grinding them for 5 hours at a speed of 2000 r / min to obtain a bright yellow clear solution. The mass ratio of the alkaline dye, dispersing agent, and deionized water is 1:0.9:15. The dispersing agent is a sulfonate surfactant, the alkaline dye is Alkaline Yellow O, and the grinding medium is zirconia beads with sizes of 0.2 mm and 0.5 mm (equal masses of the two sizes of zirconia beads are mixed). The mass ratio of the alkaline dye to the zirconia beads is 1:20.

[0036] Example 4

[0037] A method for preparing a sulfonate surfactant includes the following steps:

[0038] Step S1: Under stirring conditions at 58℃, sodium hydroxyethyl sulfonate was dispersed in dimethyl sulfoxide. After mixing evenly, 4-bromocrotonic acid and p-toluenesulfonic acid were added sequentially. The reaction was carried out for 8 hours, the pH was adjusted to 7, and the mixture was cooled to room temperature. The mixture was filtered, and the filtrate was collected. Dimethyl sulfoxide was removed by vacuum distillation. Deionized water and ethyl acetate were added for extraction. The aqueous phase was concentrated and dried under vacuum at 60℃ for 24 hours to obtain the intermediate. The molar ratio of sodium hydroxyethyl sulfonate, 4-bromocrotonic acid, and p-toluenesulfonic acid was 1:1:0.05, the mass-to-volume ratio of sodium hydroxyethyl sulfonate to dimethyl sulfoxide was 0.22 g / mL, and the volume ratio of deionized water to ethyl acetate was 6:1.

[0039] Step S2: Under stirring conditions at 67℃, 4-amino-N,N-dimethylaniline was dispersed in 2-methyltetrahydrofuran. After mixing evenly, the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride were added sequentially. The reaction was carried out for 7 hours, cooled to room temperature, filtered, and the filtrate was collected. 2-methyltetrahydrofuran was removed by vacuum distillation. Deionized water and ethyl acetate were then added for extraction. The aqueous phase was concentrated and dried under vacuum at 60℃ for 24 hours to obtain a sulfonate surfactant. The molar ratio of 4-amino-N,N-dimethylaniline, the intermediate, sodium hydroxide, and benzyltriethylammonium chloride was 1:2.2:1.1:0.1, the mass-to-volume ratio of 4-amino-N,N-dimethylaniline to 2-methyltetrahydrofuran was 0.25 g / mL, and the volume ratio of deionized water to ethyl acetate was 6:1.

[0040] A method for preparing an environmentally friendly dye for papermaking includes the following steps: mixing an alkaline dye, a dispersing agent, and deionized water evenly and then grinding them for 6 hours at a speed of 2000 r / min to obtain a bright yellow clear solution. The mass ratio of the alkaline dye, dispersing agent, and deionized water is 1:0.95:16. The dispersing agent is a sulfonate surfactant, the alkaline dye is Basic Yellow O, and the grinding medium is zirconia beads with sizes of 0.2 mm and 0.5 mm (equal masses of the two sizes of zirconia beads are mixed). The mass ratio of the alkaline dye to the zirconia beads is 1:20.

[0041] Comparative Example 1

[0042] A method for preparing an environmentally friendly dye for papermaking includes the following steps: mixing an alkaline dye, a dispersing agent, and deionized water evenly and then grinding them for 6 hours at a speed of 1900 r / min to obtain a yellow semi-transparent solution. The mass ratio of the alkaline dye, dispersing agent, and deionized water is 1:1.1:18. The dispersing agent is sodium lignosulfonate, the alkaline dye is alkaline yellow O, and the grinding medium is zirconia beads with sizes of 0.2 mm and 0.5 mm (equal masses of the two sizes of zirconia beads are mixed). The mass ratio of the alkaline dye to the zirconia beads is 1:20.

[0043] Comparative Example 2

[0044] A method for preparing an environmentally friendly dye for papermaking includes the following steps: mixing an alkaline dye and deionized water evenly and then grinding them for 6 hours at a speed of 1900 r / min to obtain a yellow turbid liquid. The mass ratio of the alkaline dye to the deionized water is 1:18, the alkaline dye is alkaline light yellow O, the grinding medium is zirconia beads with sizes of 0.2 mm and 0.5 mm (equal masses of the two sizes of zirconia beads are mixed), and the mass ratio of the alkaline dye to the zirconia beads is 1:20.

[0045] The environmentally friendly dyes for papermaking prepared in Examples 1-4 and Comparative Examples 1-2 were subjected to relevant performance tests. For the dispersion stability test, the samples were centrifuged at 2500 r / min. At a selected time point, the dye sample at 1.5 cm below the liquid surface was dissolved in DMF, and the absorbance value A at the maximum absorption wavelength was measured using a UV-Vis spectrophotometer. The uncentrifuged dye sample was also dissolved in DMF, and the absorbance value A0 at the maximum absorption wavelength was measured. The dye-to-DMF volume ratio was 1:30. Using the absorbance of the dye before centrifugation as the standard, the specific absorbance after centrifugation was calculated using the following formula: R = A / A0, where R is the specific absorbance of the dye, A0 is the absorbance of the dye before centrifugation, and A is the absorbance of the dye at the selected time. The closer the specific absorbance is to 1, the better the dispersion stability of the dye. The lightfastness test was conducted according to ISO... The color fastness test was conducted according to the standard 105-B02-2013 Textiles Color Fastness Tests, Part B02: Color Fastness to Artificial Light (Xenon Arc Lamp Test). The dyeing rate test used wet dyeing. Dye liquors before and after dyeing were taken and dissolved in acetone at a volume ratio of 1:50. The absorbance at the maximum absorption wavelength was measured. The absorbance of the dye liquor before dyeing is represented by A0, and the absorbance of the dye liquor after dyeing is represented by A. The dyeing rate was calculated using the formula: Dyeing Rate (%) = (1 - A / A0) × 100%. The color depth test used a computer colorimeter to measure the reflectance curve of the sample and record the K / S value at the maximum absorption wavelength. According to the Kubelka-Munk theory, the calculation formula is as follows: K / S = (1 - R). 2 / 2R, where K is the absorption coefficient, S is the scattering coefficient, and R is the spectral reflectance of the sample; High-temperature stability test: The sample was placed at a temperature of (60±2)℃ and a humidity of (65±5)% for 7 days, and the sample condition was observed; All tests were repeated three times and the average value was taken. The test results are shown in Tables 1 and 2. Table 1 shows that, compared with Comparative Examples 1-2, the environmentally friendly dyes for papermaking prepared in Examples 1-4 have excellent dispersion stability. Table 2 shows that the lightfastness, dyeing rate, color depth, and high-temperature stability of the environmentally friendly dyes for papermaking prepared in Examples 1-4 are significantly better than those in Comparative Examples 1-2; From the data of Examples 1 and Comparative Examples 1-2, it can be seen that using sodium lignosulfonate as a surfactant to surface-treat the basic yellow O dye can improve the dye performance to a certain extent, and using the sulfonate surfactant provided by this invention to surface-treat the basic yellow O dye can greatly improve the overall performance of the dye.

[0046] Table 1. Results of Dispersion Stability Tests for Environmentally Friendly Dyes Used in Papermaking

[0047]

[0048] Table 2. Test results of relevant performance of environmentally friendly dyes for papermaking.

[0049] Test item Fastness to light (grade) Dye uptake (%) K / S value High temperature stability Example 1 7 95.6 20.5 No delamination, no precipitation Example 2 6-7 95.4 19.6 No delamination, no precipitation Example 3 6-7 94.7 18.7 No delamination, no precipitation Example 4 6-7 95.0 19.4 No delamination, no precipitation Comparative Example 1 5 86.4 15.9 Delamination, precipitation Comparative Example 2 4 70.8 10.1 Delamination, precipitation

[0050] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. An environmentally friendly dye for papermaking, characterized in that, It includes a basic dye and a dispersing agent, wherein the dispersing agent is a sulfonate surfactant; the preparation method of the sulfonate surfactant is as follows: Step S1: Under stirring conditions at a temperature of 55-65℃, sodium hydroxyethyl sulfonate is dispersed in dimethyl sulfoxide. After mixing evenly, 4-bromocrotonic acid and p-toluenesulfonic acid are added sequentially. The reaction is carried out for 5-8 hours, the pH is adjusted to 7, and the mixture is cooled to room temperature. After purification, the intermediate is obtained. Step S2: Under stirring conditions at 60-70℃, 4-amino-N,N-dimethylaniline is dispersed in 2-methyltetrahydrofuran. After thorough mixing, the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride are added sequentially. The reaction is carried out for 6-10 hours, cooled to room temperature, and purified to obtain a sulfonate surfactant. The structural formula of the sulfonate surfactant is: ； The basic dye is Basic Yellow O.

2. The environmentally friendly dye for papermaking according to claim 1, characterized in that, The molar ratio of sodium hydroxyethyl sulfonate, 4-bromocrotonic acid, and p-toluenesulfonic acid in step S1 is 1:1.0-1.2:0.04-0.

07.

3. The environmentally friendly dye for papermaking according to claim 1, characterized in that, The mass-to-volume ratio of sodium hydroxyethyl sulfonate to dimethyl sulfoxide in step S1 is 0.19-0.25 g / mL.

4. The environmentally friendly dye for papermaking according to claim 1, characterized in that, The molar ratio of 4-amino-N,N-dimethylaniline, intermediate, sodium hydroxide, and benzyltriethylammonium chloride in step S2 is 1:2.1-2.4:1.0-1.2:0.08-0.

11.

5. The environmentally friendly dye for papermaking according to claim 1, characterized in that, The mass-to-volume ratio of 4-amino-N,N-dimethylaniline to 2-methyltetrahydrofuran in step S2 is 0.22-0.26 g / mL.

6. The method for preparing the environmentally friendly dye for papermaking according to any one of claims 1-5, characterized in that, Includes the following steps: After mixing the alkaline dye, dispersing agent, and deionized water evenly, grind them for 5-7 hours at a speed of 1800-2000 r / min to obtain the final product.

7. The method for preparing the environmentally friendly dye for papermaking according to claim 6, characterized in that, The mass ratio of the alkaline dye, dispersing agent, and deionized water is 1:0.9-1.1:15-20.

8. The method for preparing the environmentally friendly dye for papermaking according to claim 6, characterized in that, The grinding media are zirconia beads with a size of 0.2-0.5 mm.

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