Environment-friendly dye for papermaking and preparation method thereof

Abstract

The invention belongs to the technical field of papermaking dyes, and particularly relates to an environment-friendly dye for papermaking and a preparation method thereof. According to the invention, the sulfonate surfactant is prepared by a two-step method, and the sulfonate surfactant has excellent dispersibility, stability and emulsibility, and has good compatibility with alkaline auramine O; the sulfonate surfactant is compounded with the alkaline bright yellow O for use, so that the solubility, dispersion stability and high-temperature stability of the alkaline bright yellow O dye can be remarkably improved in manners of reducing interfacial tension, increasing wettability, improving permeation and the like. When the prepared environment-friendly dye is used for dyeing paper, the dye-uptake and the color fastness to light of the dye can be obviously improved, the dyeing uniformity and effect are improved, the dye waste is effectively reduced, and the requirement of green development is met.

Description

Technical Field

[0001] The invention belongs to the technical field of papermaking dyes, and particularly relates to an environmentally friendly dye for papermaking and a preparation method thereof. Background Art

[0002] Papermaking dyes are a class of chemicals used to color paper. They can increase the color and beauty of paper, improve the transparency and gloss of paper, enhance the water resistance and light resistance of paper, and improve printing performance and brightness. Papermaking dyes can be divided into several categories, such as natural dyes and synthetic dyes, cationic dyes and anionic dyes, water-soluble dyes and oil-soluble dyes. In the papermaking industry, commonly used papermaking dyes include direct dyes, basic dyes, acid dyes and sulfur dyes. Direct dyes are widely used because of their convenient dyeing, complete color spectrum and low price. They are usually dissolved in water and used directly for dyeing, but they have low solubility and can only have a small amount of combination with fibers. Basic dyes carry positive charges and have electrostatic adsorption attraction with fibers. They are suitable for dyeing in unbleached chemical pulp and mechanical pulp. However, since bleached pulp has fewer negatively charged groups and less attraction to dyes, other methods are needed to increase their retention. Acid dye molecules contain a large number of soluble groups, which affect the further combination of dye molecules and fiber surfaces. The papermaking dye industry plays an important role in providing colorful paper products, but it also faces some challenges, such as environmental pollution and cost issues. To address these problems, researchers are exploring more environmentally friendly dye preparation methods.

[0003] The patent application number CN201610808217.4 provides a sodium lignin sulfonate dye dispersant, which uses papermaking waste liquid alkaline lignin as raw material and obtains a low-fouling sodium lignin sulfonate dye dispersant product through a series of reactions. Compared with the current process, the invention not only greatly reduces the amount of blocking reagents such as epichlorohydrin and oxidants such as hydrogen peroxide, but also reduces the reaction temperature and pressure, while greatly reducing the production cost and reaction time, achieving the effect of simultaneously blocking phenolic hydroxyl groups and reducing contamination, and the lignin prepared by the invention Sodium sulfonate dispersant has good heat stability and staining resistance; the patent with application number CN201810888653.6 provides a pearlescent dye for papermaking. The raw material formula of the 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 and other raw materials, solve the problems of serious agglomeration, difficulty in dispersion, and easy agglomeration between pigment particles, enhance the smoothness of paper, decorative effect and gloss of paper, and make the paper surface smooth and delicate, good feel, good stability, and not easy to fade. The above inventions all use sodium lignin sulfonate as a surfactant. Sodium lignin sulfonate is an anionic surfactant with strong dispersing ability. Various active groups exist in its molecular structure, such as sulfonic acid group, hydroxyl group and carboxyl group, etc. These groups enable sodium lignin sulfonate to be adsorbed on the surface of various solid particles. In papermaking dyes, it is mainly used as a dye dispersant to improve the solubility and uniformity of the dye and enhance the dyeing effect. However, sodium lignin sulfonate also has its limitations. For example, darker colors may affect the whiteness of paper, and its dispersion durability is relatively poor. Summary of the invention

[0004] In view of the deficiencies in the prior art, the purpose of the present invention is to provide an environmentally friendly dye for papermaking, which has excellent comprehensive performance and meets the requirements of green development; the present 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-mentioned purpose is:

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

[0007] Step S1, dispersing sodium isethionate in dimethyl sulfoxide at a temperature of 55-65° C. with stirring, adding 4-bromocrotonic acid and p-toluenesulfonic acid in sequence after mixing evenly, reacting for 5-8 hours, adjusting the pH to 7, cooling to room temperature, and obtaining an intermediate after purification;

[0008] Step S2, dispersing 4-amino-N,N-dimethylaniline in 2-methyltetrahydrofuran at a temperature of 60-70° C. with stirring, adding the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride in sequence after mixing evenly, reacting for 6-10 hours, cooling to room temperature, and obtaining a sulfonate surfactant after purification;

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

[0010]

[0011] The invention uses sodium isethionate and 4-bromocrotonic acid as starting materials, and an esterification reaction is carried out under the catalysis of p-toluenesulfonic acid to obtain an intermediate; then, the intermediate and 4-amino-N,N-dimethylaniline are used as raw materials, and an N-alkylation reaction is carried out under the catalysis of sodium hydroxide and benzyltriethylammonium chloride to obtain a sulfonate surfactant; the sulfonate surfactant has excellent dispersibility, stability and emulsification.

[0012] In order to obtain a sulfonate surfactant and ensure the consistency of the product, 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 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, 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 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 bright yellow O.

[0014] Alkaline Yellow O is a professional paper dye widely used in the papermaking industry. It is a yellow powder dye with good suspension and bright colors, suitable for the demand for yellow dyes for paper. In the papermaking process, when Alkaline Yellow O is added to the fiber dispersion of pulp, it is beneficial to the stability of the dye molecules, improves the dispersion and uniformity of the dye in paper products, and thus improves the smoothness and strength of the paper. In addition, Alkaline Yellow O also has good suspension, which can improve the smoothness of paper products to a certain extent, and also improves the strength of paper products. Therefore, Alkaline Yellow O is widely used in the papermaking industry and is an important papermaking dye. However, alkaline yellow O has poor solubility in cold water, which means that in a cold water environment, the molecular structure of alkaline yellow O is not easy to unfold or disperse, thus showing lower stability; alkaline yellow O has good solubility in hot water and is bright yellow, but it will decompose when boiled, indicating that alkaline yellow O dye is unstable in high temperature environments. Therefore, the storage and transportation requirements of alkaline yellow O are relatively stringent; in addition, alkaline yellow O has poor light fastness and is easy to fade under light, affecting the durability of dyed items. In addition, the wastewater of alkaline yellow O dye has high chromaticity and is difficult to degrade, which can easily pollute the environment.

[0015] The present invention also provides a method for preparing an environmentally friendly dye for papermaking, comprising the following steps: uniformly mixing a basic dye, a dispersing aid and deionized water and then grinding the mixture, wherein the grinding time is 5-7 hours and the grinding speed is 1800-2000 r / min to obtain the environmentally friendly dye.

[0016] Furthermore, the mass ratio of the basic dye, the dispersing aid and the deionized water is 1:0.9-1.1:15-20; the grinding medium is zirconia beads, and the size of the zirconia beads is 0.2-0.5 mm.

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

[0018] The present invention sequentially prepares a sulfonate surfactant through esterification reaction and N-alkylation reaction. The sulfonate surfactant molecule contains N,N-dimethylaniline, acrylate and sodium sulfonate structures and has excellent dispersibility, stability and emulsification. The sulfonate surfactant provided by the present invention has good compatibility with alkaline tender yellow O. When used in combination with alkaline tender yellow O, it can not only significantly improve the solubility and dispersion stability of alkaline tender yellow O in cold water, but also improve its high temperature stability, thereby significantly improving the stability and safety of the dye during storage and transportation. In addition, the sulfonate surfactant can further improve the dispersibility of the alkaline tender yellow O dye by reducing interfacial tension, increasing wettability, improving penetration, etc., improve the rheological properties of the dye and the compatibility of the dye with the fiber, thereby improving the dye uptake and light fastness, making the dye more easily and evenly attached to the fiber, improving the uniformity and effect of dyeing, effectively reducing dye waste, reducing production costs, and reducing the impact on the environment. DETAILED DESCRIPTION

[0019] The following will be combined with the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work 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 comprises the following steps:

[0022] Step S1, dispersing sodium isethionate in dimethyl sulfoxide at a temperature of 60° C. under stirring conditions, adding 4-bromocrotonic acid and p-toluenesulfonic acid in sequence after mixing evenly, reacting for 7 hours, adjusting the pH to 7, cooling to room temperature, filtering, taking the filtrate, removing dimethyl sulfoxide by vacuum distillation, adding deionized water and ethyl acetate for extraction, concentrating the aqueous phase, and vacuum drying at 60° C. for 24 hours to obtain an intermediate, wherein the molar ratio of sodium isethionate, 4-bromocrotonic acid, and p-toluenesulfonic acid is 1:1.1:0.06, the mass volume ratio of sodium isethionate to dimethyl sulfoxide is 0.23 g / mL, and the volume ratio of deionized water to ethyl acetate is 6:1;

[0023] Step S2, at a temperature of 65° C. and under stirring conditions, dispersing 4-amino-N,N-dimethylaniline in 2-methyltetrahydrofuran, mixing well, sequentially adding the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride, reacting for 8 hours, cooling to room temperature, filtering, taking the filtrate, removing 2-methyltetrahydrofuran by vacuum distillation, adding deionized water and ethyl acetate for extraction, concentrating the aqueous phase, and vacuum drying at 60° C. for 24 hours to obtain a sulfonate surfactant, wherein the molar ratio of 4-amino-N,N-dimethylaniline, the intermediate, sodium hydroxide, and benzyltriethylammonium chloride is 1:2.3:1.1:0.09, the mass volume ratio of 4-amino-N,N-dimethylaniline to 2-methyltetrahydrofuran is 0.24 g / mL, and the volume ratio of deionized water to ethyl acetate is 6:1;

[0024] The NMR results of the modified silane coupling agent are: 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 comprises the following steps: uniformly mixing a basic dye, a dispersing aid and deionized water and then grinding the mixture, wherein the grinding time is 6 hours and the grinding speed is 1900 r / min to obtain a bright yellow clear solution, wherein the mass ratio of the basic dye, the dispersing aid and the deionized water is 1:1:18, the dispersing aid is a sulfonate surfactant, the basic dye is basic tender yellow O, zirconium oxide beads are used as grinding media, the sizes of the zirconium oxide beads are 0.2 mm and 0.5 mm (two sizes of zirconium oxide beads are mixed and used with equal mass), and the mass ratio of the basic dye to the zirconium oxide beads is 1:20.

[0026] Example 2

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

[0028] Step S1, dispersing sodium isethionate in dimethyl sulfoxide at a temperature of 55° C. under stirring, adding 4-bromocrotonic acid and p-toluenesulfonic acid in sequence after mixing evenly, reacting for 8 hours, adjusting the pH to 7, cooling to room temperature, filtering, taking the filtrate, removing dimethyl sulfoxide by vacuum distillation, adding deionized water and ethyl acetate for extraction, concentrating the aqueous phase, and vacuum drying at 60° C. for 24 hours to obtain an intermediate, wherein the molar ratio of sodium isethionate, 4-bromocrotonic acid, and p-toluenesulfonic acid is 1:1.2:0.07, the mass volume ratio of sodium isethionate to dimethyl sulfoxide is 0.19 g / mL, and the volume ratio of deionized water to ethyl acetate is 6:1;

[0029] Step S2, at a temperature of 60 ° C and stirring conditions, 4-amino-N, N-dimethylaniline is dispersed in 2-methyltetrahydrofuran, mixed evenly, and then the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride are added in sequence, reacted for 10 hours, cooled to room temperature, filtered, and the filtrate is taken. 2-methyltetrahydrofuran is removed by vacuum distillation, and deionized water and ethyl acetate are added for extraction. The aqueous phase is concentrated and vacuum dried at 60 ° C for 24 hours to obtain a sulfonate surfactant, wherein the molar ratio of 4-amino-N, N-dimethylaniline, the intermediate, sodium hydroxide, and benzyltriethylammonium chloride is 1:2.4:1.2:0.11, the mass volume ratio of 4-amino-N, N-dimethylaniline to 2-methyltetrahydrofuran is 0.22 g / mL, and the volume ratio of deionized water to ethyl acetate is 6:1.

[0030] A method for preparing an environmentally friendly dye for papermaking comprises the following steps: uniformly mixing a basic dye, a dispersing aid and deionized water and then grinding the mixture, wherein the grinding time is 7 hours and the grinding speed is 1800 r / min to obtain a bright yellow clear solution, wherein the mass ratio of the basic dye, the dispersing aid and the deionized water is 1:1.1:20, the dispersing aid is a sulfonate surfactant, the basic dye is basic tender yellow O, zirconium oxide beads are used as grinding media, the sizes of the zirconium oxide beads are 0.2 mm and 0.5 mm (two sizes of zirconium oxide beads are mixed and used with equal mass), and the mass ratio of the basic dye to the zirconium oxide beads is 1:20.

[0031] Example 3

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

[0033] Step S1, dispersing sodium isethionate in dimethyl sulfoxide at a temperature of 65° C. under stirring conditions, adding 4-bromocrotonic acid and p-toluenesulfonic acid in sequence after mixing evenly, reacting for 5 hours, adjusting the pH to 7, cooling to room temperature, filtering, taking the filtrate, removing dimethyl sulfoxide by vacuum distillation, adding deionized water and ethyl acetate for extraction, concentrating the aqueous phase, and vacuum drying at 60° C. for 24 hours to obtain an intermediate, wherein the molar ratio of sodium isethionate, 4-bromocrotonic acid, and p-toluenesulfonic acid is 1:1:0.04, the mass volume ratio of sodium isethionate to dimethyl sulfoxide is 0.25 g / mL, and the volume ratio of deionized water to ethyl acetate is 6:1;

[0034] Step S2, at a temperature of 70 ° C, under stirring conditions, 4-amino-N, N-dimethylaniline is dispersed in 2-methyltetrahydrofuran, mixed evenly, and then the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride are added in sequence, reacted for 6 hours, cooled to room temperature, filtered, and the filtrate is taken. 2-methyltetrahydrofuran is removed by vacuum distillation, and deionized water and ethyl acetate are added for extraction. The aqueous phase is concentrated and vacuum dried at 60 ° C for 24 hours to obtain a sulfonate surfactant, wherein the molar ratio of 4-amino-N, N-dimethylaniline, the intermediate, sodium hydroxide, and benzyltriethylammonium chloride is 1:2.1:1:0.08, the mass volume ratio of 4-amino-N, N-dimethylaniline to 2-methyltetrahydrofuran is 0.26 g / mL, and the volume ratio of deionized water to ethyl acetate is 6:1.

[0035] A method for preparing an environmentally friendly dye for papermaking comprises the following steps: uniformly mixing a basic dye, a dispersing aid and deionized water and then grinding the mixture, wherein the grinding time is 5 hours and the grinding speed is 2000 r / min to obtain a bright yellow clear solution, wherein the mass ratio of the basic dye, the dispersing aid and the deionized water is 1:0.9:15, the dispersing aid is a sulfonate surfactant, the basic dye is basic tender yellow O, the grinding medium is zirconia beads, the sizes of the zirconia beads are 0.2 mm and 0.5 mm (two sizes of zirconia beads are mixed and used with equal mass), and the mass ratio of the basic dye to the zirconia beads is 1:20.

[0036] Example 4

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

[0038] Step S1, dispersing sodium isethionate in dimethyl sulfoxide at a temperature of 58° C. under stirring, adding 4-bromocrotonic acid and p-toluenesulfonic acid in sequence after mixing evenly, reacting for 8 hours, adjusting the pH to 7, cooling to room temperature, filtering, taking the filtrate, removing dimethyl sulfoxide by vacuum distillation, adding deionized water and ethyl acetate for extraction, concentrating the aqueous phase, and vacuum drying at 60° C. for 24 hours to obtain an intermediate, wherein the molar ratio of sodium isethionate, 4-bromocrotonic acid, and p-toluenesulfonic acid is 1:1:0.05, the mass volume ratio of sodium isethionate to dimethyl sulfoxide is 0.22 g / mL, and the volume ratio of deionized water to ethyl acetate is 6:1;

[0039] Step S2, at a temperature of 67° C. and under stirring conditions, 4-amino-N,N-dimethylaniline is dispersed in 2-methyltetrahydrofuran, mixed evenly, and then the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride are added in sequence, reacted for 7 hours, cooled to room temperature, filtered, and the filtrate is taken. 2-methyltetrahydrofuran is removed by vacuum distillation, deionized water and ethyl acetate are added for extraction, the aqueous phase is concentrated, and vacuum dried at 60° C. for 24 hours to obtain a sulfonate surfactant, wherein the molar ratio of 4-amino-N,N-dimethylaniline, the intermediate, sodium hydroxide, and benzyltriethylammonium chloride is 1:2.2:1.1:0.1, the mass volume ratio of 4-amino-N,N-dimethylaniline to 2-methyltetrahydrofuran is 0.25 g / mL, and the volume ratio of deionized water to ethyl acetate is 6:1.

[0040] A method for preparing an environmentally friendly dye for papermaking comprises the following steps: uniformly mixing a basic dye, a dispersing aid and deionized water and then grinding the mixture, wherein the grinding time is 6 hours and the grinding speed is 2000 r / min to obtain a bright yellow clear solution, wherein the mass ratio of the basic dye, the dispersing aid and the deionized water is 1:0.95:16, the dispersing aid is a sulfonate surfactant, the basic dye is basic tender yellow O, zirconium oxide beads are used as grinding media, the sizes of the zirconium oxide beads are 0.2 mm and 0.5 mm (two sizes of zirconium oxide beads are mixed and used with equal mass), and the mass ratio of the basic dye to the zirconium oxide beads is 1:20.

[0041] Comparative Example 1

[0042] A method for preparing an environmentally friendly dye for papermaking comprises the following steps: uniformly mixing a basic dye, a dispersing aid and deionized water and then grinding the mixture, wherein the grinding time is 6 hours and the grinding speed is 1900 r / min to obtain a yellow translucent solution, wherein the mass ratio of the basic dye, the dispersing aid and the deionized water is 1:1.1:18, the dispersing aid is sodium lignin sulfonate, the basic dye is basic tender yellow O, zirconium oxide beads are used as grinding media, the sizes of the zirconium oxide beads are 0.2 mm and 0.5 mm (two sizes of zirconium oxide beads are mixed and used with equal mass), and the mass ratio of the basic dye to the zirconium oxide beads is 1:20.

[0043] Comparative Example 2

[0044] A method for preparing an environmentally friendly dye for papermaking comprises the following steps: mixing a basic dye and deionized water uniformly and then grinding them, wherein the grinding time is 6 hours and the grinding speed is 1900 r / min to obtain a yellow turbid liquid, wherein the mass ratio of the basic dye to the deionized water is 1:18, the basic dye is basic tender yellow O, zirconium oxide beads are used as grinding media, the sizes of the zirconium oxide beads are 0.2 mm and 0.5 mm (two sizes of zirconium oxide beads are mixed and used with equal mass), and the mass ratio of the basic dye to the zirconium oxide 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. Dispersion stability test: The sample was centrifuged at 2500 r / min, and the dye at 1.5 cm below the liquid surface was dissolved in DMF at a selected time point, and the absorbance value A at the maximum absorption wavelength was measured by a UV-visible spectrophotometer; the uncentrifuged dye was dissolved in DMF, and the absorbance value A0 at the maximum absorption wavelength was measured, and the volume ratio of the dye to DMF was 1:30; the absorbance of the dye before centrifugation was used as the standard, and the specific absorbance after centrifugation was calculated as follows: 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 is; the light fastness test is carried out according to ISO 105-B02-2013 Textile Color Fastness Test Part B02 Xenon Arc Lamp Test Standard for Color Fastness to Artificial Light; The dye uptake test adopts wet dyeing, and the dye solution before and after dyeing is dissolved in acetone. The volume ratio of dye solution to acetone is 1:50. The absorbance at the maximum absorption wavelength is measured. The absorbance of the dye solution before dyeing is represented by A0, and the absorbance of the dye solution after dyeing is represented by A. The dye uptake is calculated. The dye uptake calculation formula is: dye uptake (%) = (1-A / A0) × 100%; The color depth test adopts a computer colorimeter to measure the reflectance curve of the sample, and records 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; the high temperature stability test is to place the sample at a temperature of (60±2)℃ and a humidity of (65±5)% for 7d, and observe the state of the sample; the above tests are repeated three times to take the average value, and the test results are shown in Table 1 and Table 2. It can be seen from the data in Table 1 that compared with Comparative Examples 1-2, the environmentally friendly dyes for papermaking prepared in Examples 1-4 have excellent dispersion stability. It can be seen from the data in Table 2 that the light fastness, dyeing rate, color depth value, 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; it can be seen from the data in Example 1 and Comparative Examples 1-2 that using sodium lignin sulfonate as a surfactant to surface treat the alkaline tender yellow O dye can improve the performance of the dye to a certain extent, and using the sulfonate surfactant provided by the present invention to surface treat the alkaline tender yellow O dye can greatly improve the comprehensive performance of the dye.

[0046] Table 1 Test results of dispersion stability of environmentally friendly dyes for papermaking

[0047]

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

[0049] Test items Color fastness to sunlight (grade) Dyeing rate (%) K / S value High temperature stability Example 1 7 95.6 20.5 No stratification or precipitation Example 2 6-7 95.4 19.6 No stratification or precipitation Example 3 6-7 94.7 18.7 No stratification or precipitation Example 4 6-7 95.0 19.4 No stratification or precipitation Comparative Example 1 5 86.4 15.9 Stratification and precipitation Comparative Example 2 4 70.8 10.1 Stratification and precipitation

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

Claims

1. An environmentally friendly dye for papermaking, characterized in that: The invention comprises a basic dye and a dispersing aid, wherein the dispersing aid is a sulfonate surfactant; and the preparation method of the sulfonate surfactant is as follows: Step S1, dispersing sodium isethionate in dimethyl sulfoxide at a temperature of 55-65° C. with stirring, adding 4-bromocrotonic acid and p-toluenesulfonic acid in sequence after mixing evenly, reacting for 5-8 hours, adjusting the pH to 7, cooling to room temperature, and obtaining an intermediate after purification; Step S2, at a temperature of 60-70° C. and under stirring conditions, 4-amino-N,N-dimethylaniline is dispersed in 2-methyltetrahydrofuran, mixed evenly, and then the intermediate obtained in step S1, sodium hydroxide, and benzyltriethylammonium chloride are added in sequence, reacted for 6-10 hours, cooled to room temperature, and purified to obtain a sulfonate surfactant, the structural formula of which is:

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 volume ratio of sodium isethionate 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 volume ratio of 4-amino-N,N-dimethylaniline to 2-methyltetrahydrofuran in step S2 is 0.22-0.26 g / mL.

6. The environmentally friendly dye for papermaking according to claim 1, characterized in that: The basic dye is basic bright yellow O.

7. The method for preparing an environmentally friendly dye for papermaking according to any one of claims 1 to 6, characterized in that: The following steps are involved: The basic dye, dispersing aid and deionized water are uniformly mixed and then ground. The grinding time is 5-7 hours and the grinding speed is 1800-2000r / min.

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

9. The method for preparing the environmentally friendly dye for papermaking according to claim 7, characterized in that: The grinding medium is zirconia beads, and the size of the zirconia beads is 0.2-0.5 mm.

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