Preparation process of high-stability lignin sulfonate sodium dispersant for dyes

Abstract

This invention discloses a preparation process for a high-stability sodium lignosulfonate dispersant for dyes, belonging to the field of dispersant technology. It solves the problem that when the sulfonation level of sodium lignosulfonate dispersant is too high, it easily desorbs from the surface of hydrophobic disperse dyes at high temperatures, leading to dye aggregation, crystal growth, and irreversible problems such as uneven dyeing and decreased color fastness. Furthermore, the multivariate influence makes it difficult to trace the root cause of the problem. The process includes the following steps: S1 Raw material inspection step, where incoming raw material components are inspected to confirm that key indicators meet control standards. This invention achieves the technical indicators of batch-to-batch performance deviation CV < 3% and dispersion stability ≥ 95% after 90 minutes of flattening at 130℃ by adding protective sensitive components in stages, controlling the order of addition to ensure that each component functions in the correct position, and reducing batch-to-batch fluctuations through full-process monitoring.

Description

Technical Field

[0001] This invention relates to the field of dispersant technology, and in particular to a preparation process of a highly stable sodium lignosulfonate dispersant for dyes. Background Technology

[0002] Sodium lignosulfonate for dyes is a natural anionic polymeric dispersant, commonly used in dye processing. Primarily derived from pulping waste liquor, it disperses water-insoluble dye particles uniformly in water through electrostatic repulsion and steric hindrance caused by molecular adsorption. It also prevents dye aggregation and precipitation during high-temperature dyeing, making it suitable for the commercial processing of disperse and vat dyes. Its preparation primarily uses pulping waste liquor as raw material. Traditional processes rely on sulfite waste liquor undergoing calcification, acid dissolution, and sodium conversion. Alkaline pulping black liquor undergoes sulfonation modification to improve water solubility. Modern processes also incorporate catalytic oxidation and microwave-assisted methods to optimize sulfonation. It can also be purified from biomass raw materials such as straw. The overall process is developing towards cleaner, more efficient, higher-purity, and higher-sulfonation-degree production. In the field of dye applications, sodium lignosulfonate dispersants, when used in high-temperature, high-pressure dyeing of polyester fabrics at around 130°C to treat certain relatively weakly hydrophobic disperse dyes, can weaken the anchoring effect between the dispersant and the dye particle surface due to excessively strong affinity for water at high temperatures. This exacerbates the desorption of the dispersant from the dye surface, thereby damaging the electrostatic repulsion and steric hindrance protective layer of the dye particles, leading to dye particle aggregation and even crystal growth. This is due to factors such as the molecular weight distribution of the dispersant, sulfonation sites, residual impurity content, the specific chemical structure of the dye, and the complex composition of the dye. Multiple variables, such as the compatibility of additives and the concentration of metal ions in the water, jointly affect the final high-temperature dispersion stability. A single indicator, such as the degree of sulfonation, cannot fully predict the actual performance. In industrial practice, dispersants are usually used in the form of compound systems, such as sodium lignosulfonate and naphthalenesulfonic acid formaldehyde condensate, and nonionic surfactants. This further increases the complexity of tracing the root cause of the problem. Once this problem occurs, it will cause irreversible aggregation of dyes during high-temperature dyeing. The direct consequences are color spots, color patches, uneven dyeing on the fabric surface, and even staining of the dyeing vat and a decrease in color fastness. In severe cases, rework or scrapping is required, resulting in significant economic losses.

[0003] Therefore, a preparation process for a highly stable sodium lignosulfonate dispersant for dyes is proposed to solve or alleviate the above problems. Summary of the Invention

[0004] The purpose of this invention is to address the shortcomings of existing technologies by proposing a preparation process for a highly stable sodium lignosulfonate dispersant for dyes.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A process for preparing a highly stable sodium lignosulfonate dispersant for dyes includes the following steps: S1 Raw Material Inspection Steps: Incoming quality inspection of each raw material component is carried out to confirm that key indicators meet control standards. The S2 dispersion preparation step involves dissolving the main components of the dispersant, the chelating agent system, the pH buffer system, and the filler in a portion of deionized water to obtain solution A. In step S3, the A liquid is mixed with the crude dye and then wet-milled until the dye particle size reaches the target value. In step S4, the steric hindrance enhancement and temperature compensation components and the biodegradable chelate-dispersion bifunctional polymer are dissolved in a portion of deionized water to obtain solution B, which is then mixed into the grinding slurry obtained in step S3 by low-speed stirring. In step S5, the supersaturation control and crystal growth inhibition components are dissolved in the remaining deionized water to obtain solution C, which is then mixed into the mixed slurry obtained in step S4 in a specific order using a low-speed stirring method. S6 Finished Product Quality Inspection and Post-Processing Steps: The obtained finished products are inspected for quality, and after confirming that all indicators are qualified, they are packaged or dried.

[0006] Preferably, the S1 raw material inspection step involves inspecting the incoming quality of each raw material component to confirm that key indicators meet control standards, specifically including the following steps: S1-1 tested graded sulfonated sodium lignin sulfonate, including the following tests: degree of sulfonation, determined by potentiometric titration, controlled within the range of 1.1-1.7 mmol / g; and the percentage of α-position sulfonation sites, determined by... 13 CNMR or two-dimensional HSQCNMR detection, controlled at ≥60%; molecular weight distribution, detected by gel permeation chromatography, confirming the presence of low molecular weight fractions with a weight average molecular weight of 3000-6000 Da and high molecular weight fractions with a weight average molecular weight of 15000-25000 Da, with a mass ratio of 35:65-45:55. S1-2 tests the hyperbranched polyglycerol modified sodium lignosulfonate. The test items include: grafting rate, which is detected by TGA thermogravimetric analysis and controlled within 15-25 wt%; water solubility, a 5% aqueous solution should be clear and transparent. S1-3 tested the blend of acetyl sulfonate formaldehyde condensate and sulfonated ketone aldehyde resin and confirmed that the blend mass ratio was 6:4-8:2 and the degree of condensation n of acetyl sulfonate formaldehyde condensate was 5-8. S1-4 tested the polyoxyethylene-polyoxypropylene block copolymer and confirmed its lower critical solution temperature ≥100℃ by cloud point determination. S1-5 was used to test for sodium sulfonyl β-cyclodextrin, using... 1 HNMR was used to determine the degree of sulfobutyl substitution, which was controlled to be 6-7. S1-6 was tested for nano-silica hydrosols. The particle size was determined to be 8-20 nm using dynamic light scattering method, and the solid content was determined to be 25-35 wt% using drying method. S1-7 tested sodium polyaspartate and polyvinylpyrrolidone separately, and confirmed by gel permeation chromatography that the weight average molecular weight of sodium polyaspartate was 3000-5000 Da and the weight average molecular weight of polyvinylpyrrolidone was 8000-15000 Da. S1-8 tests the deionized water using a conductivity meter, controlling the conductivity to be ≤30μS / cm.

[0007] Preferably, the S2 dispersant preparation step involves dissolving the dispersant main component, chelating agent system, pH buffer system, and filler in a portion of deionized water to obtain solution A, specifically including the following steps: S2-1 Add 40-50 parts by weight of deionized water to a stainless steel mixing tank with a heating jacket, turn on the jacket heating to raise the temperature to 40-50℃, turn on the stirring and set the stirring speed to 60-80 rpm. S2-2 Under the temperature conditions of step S2-1, add 25-32 parts by weight of gradient sulfonated sodium lignin sulfonate in batches, with each addition not exceeding 1 / 4 of the total amount. Add the next batch after the previous batch has basically dissolved. Increase the stirring speed to 100-120 rpm. After all the ingredients have been added, continue stirring for 25-35 minutes until completely dissolved. S2-3 After step S2-2 is completed, add 10-15 parts by weight of the blend of acetylene sulfonic acid formaldehyde condensate and sulfonated ketone aldehyde resin. The addition rate is controlled at 2-6 kg / min, and the stirring speed is maintained at 100-120 rpm. After the addition is completed, continue stirring for 15-25 minutes until completely dissolved. S2-4 After step S2-3 is completed, add 1-2 parts by weight of disodium ethylenediaminetetraacetate and 0.5-1.5 parts by weight of sodium citrate in sequence. Stir for 8-12 minutes after each addition until completely dissolved, with a stirring speed of 80-100 rpm. Disodium ethylenediaminetetraacetate must be added before sodium citrate. After step S2-4 is completed, add 0.5-1.0 parts by weight of disodium hydrogen phosphate, stir for 3-8 minutes, then slowly add 0.5-1.0 parts by weight of maleic acid, stir for 8-12 minutes, and check the pH value of solution A to control it at 5.5-6.5; S2-6 After step S2-5 is completed, add 1-4 parts by weight of sodium sulfate, stir for 8-12 minutes, and check the conductivity of solution A to be ≤40μS / cm to obtain solution A.

[0008] Preferably, the S3 wet milling step involves mixing the A solution with the crude dye and then performing wet milling until the dye particle size reaches the target value, specifically including the following steps: S3-1 Pre-dispersion: Mix the A liquid and the crude dye in a slurry tank according to the formula ratio, and pre-dispersion for 8-12 minutes using a high-speed disperser at a linear velocity ≥18m / s to obtain a uniform slurry; S3-2 Grinding: The slurry is fed into a horizontal sand mill for wet grinding. The horizontal sand mill uses 0.3-0.5mm diameter beads as grinding media, with a bead filling rate of 70-80%. The volume ratio of slurry to beads is 1:1.5-1:2. The grinding speed is controlled in stages. The initial stage linear velocity is 7-9m / s, and after running for 10-20 minutes, it is gradually increased to 11-13m / s. During the grinding process, the slurry temperature is controlled to ≤45℃ by circulating cooling water in the jacket. An external circulation continuous grinding mode is adopted. S3-3 Process Monitoring: During the grinding process, samples are taken every 25-35 minutes. The D90 particle size is detected using a laser particle size analyzer. At the same time, the slurry viscosity is monitored and controlled at 200-500 mPa·s. When the viscosity exceeds 500 mPa·s, deionized water is added to adjust it. S3-4 Endpoint Judgment: When two consecutive sampling tests show D90≤1.0μm, the grinding is deemed qualified; S3-5 Filtration: After grinding, the slurry is filtered through a 150-250 mesh stainless steel screen to remove nodule fragments and coarse particles. The filtrate is then transferred to an intermediate storage tank.

[0009] Preferably, the S4 functional additive solution preparation and mixing step involves dissolving the steric hindrance enhancement and temperature compensation components and the biodegradable chelate-dispersion bifunctional polymer in a portion of deionized water to obtain solution B, which is then mixed into the grinding slurry obtained in step S3 using a low-speed stirring method. Specifically, this includes the following steps: S4-1 Add 15-25 parts by weight of deionized water to the second stainless steel mixing tank, turn on the jacket to heat to 35-45℃, and stir at 50-70 rpm. S4-2 Slowly add 8-14 parts by weight of hyperbranched polyglycerol modified sodium lignosulfonate, increase the stirring speed to 80-100 rpm, and stir for 25-35 minutes until completely dissolved, during which the dissolution temperature shall not exceed 55℃; S4-3 After step S4-2 is completed, add the polyoxyethylene-polyoxypropylene block copolymer, maintain the stirring speed at 70-90 rpm, and stir for 12-25 minutes until completely dissolved; After step S4-3 is completed, add 1-3 parts by weight of sodium polyaspartate and stir for 8-12 minutes until completely dissolved to obtain solution B. S4-5 Slowly inject liquid B into the slurry obtained in step S3. The injection speed is controlled at 8-15 kg / min and the mixing speed is 60-80 rpm. After the full amount is injected, continue mixing for 15-25 minutes. It is strictly forbidden to use a high-speed disperser when mixing liquid B; only low-speed mixing is used. After the S4-6B solution was mixed in, the dynamic light scattering particle size of the clear liquid portion of the formula was measured to be <50nm and the Zeta potential was ≤-35mV.

[0010] Preferably, the S5 step of preparing and mixing the control component solution involves dissolving the supersaturation control and crystal growth inhibition components in the remaining deionized water to obtain solution C, and then mixing it into the mixed slurry obtained in step S4 in a specific order using a low-speed stirring method. Specifically, this includes the following steps: S5-1 Add 7-12 parts by weight of the remaining deionized water to the third stainless steel mixing tank, stir at room temperature, and stir at a speed of 50-70 rpm. First, add 1-3 parts by weight of nano-silica hydrosol to S5-2 and stir for 8-12 minutes to disperse it evenly. S5-3 Then add 1-2 parts by weight of polyvinylpyrrolidone and stir for 12-18 minutes until completely dissolved; Finally, add 2-4 parts by weight of sodium sulfobutyl β-cyclodextrin salt to S5-4, stir for 15-25 minutes until completely dissolved, and obtain solution C; S5-5 Slowly inject liquid C into the mixed slurry obtained in step S4, controlling the injection speed at 6-10 kg / min and the stirring speed at 60-80 rpm. After the full amount is injected, continue stirring for 25-35 minutes.

[0011] Preferably, the S6 finished product quality inspection and post-processing step involves inspecting the quality of the obtained finished product, confirming that all indicators are qualified, and then packaging or drying it. Specifically, this includes the following steps: S6-1 conducts quality inspection on the obtained finished product. The inspection items include: pH value controlled between 5.5 and 6.5, measured directly with a pH meter; particle size distribution D90 ≤ 1.0 μm, detected using a laser particle size analyzer; Zeta potential ≤ -35 ​​mV, detected using a Zeta potential analyzer; dynamic light scattering particle size of the clear liquid portion < 50 nm; conductivity ≤ 30 μS / cm; high-temperature dispersion stability not less than 95% after being flattened at 130℃ for 90 minutes, detected using a combination of tube sealing and centrifugal sedimentation. The test method for the high temperature dispersion stability of S6-2 is as follows: after diluting the finished product according to the actual dyeing concentration, put it into a sealed tube, place it in a constant temperature bath at 130℃ for 90 minutes, take it out and let it cool naturally to room temperature, centrifuge at 2500-3500rpm for 25-35 minutes, measure the absorbance of the supernatant and compare it with the unheated control sample, and calculate the stability percentage. For products supplied in liquid form, S6-3 should be directly filled and sealed, and stored at 5-30℃ in the dark. For products supplied in powder form, spray drying should be used, with the inlet temperature controlled at 180-200℃ and the outlet temperature controlled at 70-80℃. The moisture content of the powder product should be ≤5%. After drying, the high-temperature dispersion stability should be retested to confirm that there is no performance degradation.

[0012] The present invention has the following beneficial effects: This invention achieves the technical indicators of batch-to-batch performance deviation CV < 3% and dispersion stability ≥ 95% after 90 minutes of flattening at 130℃ by adding protective sensitive components in stages, controlling the order of addition to ensure that each component plays its role in the correct position, and reducing batch-to-batch fluctuations through full-process monitoring. Attached Figure Description

[0013] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0014] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0015] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0016] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0017] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0018] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product of this invention is in use, or the orientation or positional relationship commonly understood by those skilled in the art. They are only used to facilitate the description of this invention and to simplify the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0019] Furthermore, the terms "first," "second," and "third" are used only to distinguish descriptions and should not be interpreted as indicating or implying relative importance.

[0020] In the description of this invention, it should also be noted that, unless otherwise explicitly specified and limited, the terms "set," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0021] A preparation process for a highly stable sodium lignosulfonate dispersant for dyes, such as... Figure 1 As shown, it includes the following steps: S1 Raw Material Inspection Steps: Incoming quality inspection of each raw material component is carried out to confirm that key indicators meet control standards. More specifically, S1-1 tested graded sulfonated sodium lignin sulfonate, including the following tests: degree of sulfonation, determined by potentiometric titration, controlled within the range of 1.1-1.7 mmol / g; and the percentage of α-position sulfonation sites, determined by... 13 CNMR or two-dimensional HSQCNMR detection, controlled at ≥60%; molecular weight distribution, detected by gel permeation chromatography, confirming the presence of low molecular weight fractions with a weight average molecular weight of 3000-6000 Da and high molecular weight fractions with a weight average molecular weight of 15000-25000 Da, with a mass ratio of 35:65-45:55. S1-2 tests the hyperbranched polyglycerol modified sodium lignosulfonate. The test items include: grafting rate, which is detected by TGA thermogravimetric analysis and controlled within 15-25 wt%; water solubility, a 5% aqueous solution should be clear and transparent. S1-3 tested the blend of acetyl sulfonate formaldehyde condensate and sulfonated ketone aldehyde resin and confirmed that the blend mass ratio was 6:4-8:2 and the degree of condensation n of acetyl sulfonate formaldehyde condensate was 5-8. S1-4 tested the polyoxyethylene-polyoxypropylene block copolymer and confirmed its lower critical solution temperature ≥100℃ by cloud point determination. S1-5 was used to test for sodium sulfonyl β-cyclodextrin, using... 1 HNMR was used to determine the degree of sulfobutyl substitution, which was controlled to be 6-7. S1-6 was tested for nano-silica hydrosols. The particle size was determined to be 8-20 nm using dynamic light scattering method, and the solid content was determined to be 25-35 wt% using drying method. S1-7 tested sodium polyaspartate and polyvinylpyrrolidone separately, and confirmed by gel permeation chromatography that the weight average molecular weight of sodium polyaspartate was 3000-5000 Da and the weight average molecular weight of polyvinylpyrrolidone was 8000-15000 Da. S1-8 tests deionized water using a conductivity meter, controlling the conductivity to be ≤30μS / cm; The S2 dispersion preparation step involves dissolving the main components of the dispersant, the chelating agent system, the pH buffer system, and the filler in a portion of deionized water to obtain solution A. More specifically, S2-1 Add 40-50 parts by weight of deionized water to a stainless steel mixing tank with a heating jacket, turn on the jacket heating to raise the temperature to 40-50℃, turn on the stirring and set the stirring speed to 60-80 rpm. S2-2 Under the temperature conditions of step S2-1, add 25-32 parts by weight of gradient sulfonated sodium lignin sulfonate in batches, with each addition not exceeding 1 / 4 of the total amount. Add the next batch after the previous batch has basically dissolved. Increase the stirring speed to 100-120 rpm. After all the ingredients have been added, continue stirring for 25-35 minutes until completely dissolved. S2-3 After step S2-2 is completed, add 10-15 parts by weight of the blend of acetylene sulfonic acid formaldehyde condensate and sulfonated ketone aldehyde resin. The addition rate is controlled at 2-6 kg / min, and the stirring speed is maintained at 100-120 rpm. After the addition is completed, continue stirring for 15-25 minutes until completely dissolved. S2-4 After step S2-3 is completed, add 1-2 parts by weight of disodium ethylenediaminetetraacetate and 0.5-1.5 parts by weight of sodium citrate in sequence. Stir for 8-12 minutes after each addition until completely dissolved, with a stirring speed of 80-100 rpm. Disodium ethylenediaminetetraacetate must be added before sodium citrate. After step S2-4 is completed, add 0.5-1.0 parts by weight of disodium hydrogen phosphate, stir for 3-8 minutes, then slowly add 0.5-1.0 parts by weight of maleic acid, stir for 8-12 minutes, and check the pH value of solution A to control it at 5.5-6.5; S2-6 After step S2-5 is completed, add 1-4 parts by weight of sodium sulfate, stir for 8-12 minutes, and check that the conductivity of solution A is controlled to be ≤40μS / cm to obtain solution A; S3 wet milling step: Mix solution A with crude dye and then perform wet milling until the dye particle size reaches the target value. More specifically, S3-1 Pre-dispersion: Mix solution A and crude dye in a slurry tank according to the formula ratio, and pre-disperde using a high-speed disperser at a linear velocity ≥18m / s for 8-12 minutes to obtain a uniform slurry; S3-2 Grinding: The slurry is fed into a horizontal sand mill for wet grinding. The horizontal sand mill uses 0.3-0.5mm diameter beads as grinding media, with a bead filling rate of 70-80%. The volume ratio of slurry to beads is 1:1.5-1:2. The grinding speed is controlled in stages. The initial stage linear velocity is 7-9m / s, and after running for 10-20 minutes, it is gradually increased to 11-13m / s. During the grinding process, the slurry temperature is controlled to ≤45℃ by circulating cooling water in the jacket. An external circulation continuous grinding mode is adopted. S3-3 Process Monitoring: During the grinding process, samples are taken every 25-35 minutes. The D90 particle size is detected using a laser particle size analyzer. At the same time, the slurry viscosity is monitored and controlled at 200-500 mPa·s. When the viscosity exceeds 500 mPa·s, deionized water is added to adjust it. S3-4 Endpoint Judgment: When two consecutive sampling tests show D90≤1.0μm, the grinding is deemed qualified; S3-5 Filtration: After grinding, the slurry is filtered through a 150-250 mesh stainless steel screen to remove noreite fragments and coarse particles. The filtrate is then transferred to an intermediate storage tank. In step S4, the steric hindrance enhancement and temperature compensation components and the biodegradable chelate-dispersion bifunctional polymer are dissolved in a portion of deionized water to obtain solution B, which is then mixed into the grinding slurry obtained in step S3 by low-speed stirring. More specifically, S4-1 Add 15-25 parts by weight of deionized water to the second stainless steel mixing tank, turn on the jacket to heat to 35-45℃, and stir at 50-70 rpm. S4-2 Slowly add 8-14 parts by weight of hyperbranched polyglycerol modified sodium lignosulfonate, increase the stirring speed to 80-100 rpm, and stir for 25-35 minutes until completely dissolved, during which the dissolution temperature shall not exceed 55℃; S4-3 After step S4-2 is completed, add the polyoxyethylene-polyoxypropylene block copolymer, maintain the stirring speed at 70-90 rpm, and stir for 12-25 minutes until completely dissolved; After step S4-3 is completed, add 1-3 parts by weight of sodium polyaspartate and stir for 8-12 minutes until completely dissolved to obtain solution B. S4-5 Slowly inject liquid B into the slurry obtained in step S3. The injection speed is controlled at 8-15 kg / min and the mixing speed is 60-80 rpm. After the full amount is injected, continue mixing for 15-25 minutes. It is strictly forbidden to use a high-speed disperser when mixing liquid B; only low-speed mixing is used. After the S4-6B solution was mixed in, the dynamic light scattering particle size of the clear liquid portion of the formula was measured to be <50nm and the Zeta potential was ≤-35mV. In step S5, the supersaturation control and crystal growth inhibition components are dissolved in the remaining deionized water to obtain solution C, which is then mixed into the mixed slurry obtained in step S4 in a specific order using a low-speed stirring method. More specifically, S5-1 Add 7-12 parts by weight of the remaining deionized water to the third stainless steel mixing tank, stir at room temperature, and stir at a speed of 50-70 rpm. First, add 1-3 parts by weight of nano-silica hydrosol to S5-2 and stir for 8-12 minutes to disperse it evenly. S5-3 Then add 1-2 parts by weight of polyvinylpyrrolidone and stir for 12-18 minutes until completely dissolved; Finally, add 2-4 parts by weight of sodium sulfobutyl β-cyclodextrin salt to S5-4, stir for 15-25 minutes until completely dissolved, and obtain solution C; S5-5 Slowly inject liquid C into the mixed slurry obtained in step S4, with the injection speed controlled at 6-10 kg / min and the stirring speed at 60-80 rpm. After the full amount is injected, continue stirring for 25-35 minutes. S6 Finished Product Quality Inspection and Post-processing Steps: The obtained finished products are inspected for quality, and after confirming that all indicators are qualified, they are packaged or dried. More specifically, S6-1 conducts quality inspection on the obtained finished product. The inspection items include: pH value controlled between 5.5 and 6.5, measured directly with a pH meter; particle size distribution D90 ≤ 1.0 μm, detected using a laser particle size analyzer; Zeta potential ≤ -35 ​​mV, detected using a Zeta potential analyzer; dynamic light scattering particle size of the clear liquid portion < 50 nm; conductivity ≤ 30 μS / cm; high-temperature dispersion stability not less than 95% after being flattened at 130℃ for 90 minutes, detected using a combination of tube sealing and centrifugal sedimentation. The test method for the high temperature dispersion stability of S6-2 is as follows: after diluting the finished product according to the actual dyeing concentration, put it into a sealed tube, place it in a constant temperature bath at 130℃ for 90 minutes, take it out and let it cool naturally to room temperature, centrifuge at 2500-3500rpm for 25-35 minutes, measure the absorbance of the supernatant and compare it with the unheated control sample, and calculate the stability percentage. For products supplied in liquid form, S6-3 should be directly filled and sealed, and stored at 5-30℃ in the dark. For products supplied in powder form, spray drying should be used, with the inlet temperature controlled at 180-200℃ and the outlet temperature controlled at 70-80℃. The moisture content of the powder product should be ≤5%. After drying, the high-temperature dispersion stability should be retested to confirm that there is no performance degradation. In the above steps, at the formulation level, this dispersant abandons the traditional approach of solely pursuing high sulfonation degree. Instead, it selects graded sulfonated sodium lignin sulfonate with a sulfonation degree controlled within the range of 1.1 to 1.7 mmol / g as the main dispersant. The sulfonation degree level is adjusted accordingly within this range based on the hydrophobicity of the dye being treated. For azo dyes with weaker hydrophobicity, a lower value of 1.1 to 1.3 mmol / g is used, while for heterocyclic dyes with stronger hydrophobicity, a higher value of 1.5 to 1.7 mmol / g is used. This provides sufficient electrostatic repulsion while avoiding the problem of dispersant molecules desorbing from the dye particle surface back into the aqueous phase at a high temperature of 130°C due to excessive hydrophilicity.

[0022] Furthermore, this dispersant imposes two unconventional molecular-level requirements on this gradient sulfonated sodium lignin sulfonate: The first requirement is a bimodal molecular weight distribution, meaning that the product simultaneously contains a low molecular weight fraction with a weight average molecular weight of 3,000 to 6,000 Da and a high molecular weight fraction with a weight average molecular weight of 15,000 to 25,000 Da, with the mass ratio of the two controlled between 35:65 and 45:55. The low molecular weight fraction has a fast diffusion rate and can quickly wet the newly formed surface of the dye particles during the grinding stage, while the high molecular weight fraction provides multi-point adsorption and a thick steric hindrance protective layer. The two form a relay-style coverage on a time scale. The second requirement is that the proportion of α-sulfonated sites to total sulfonated sites is not less than 60%. This is because the carbon-sulfur bond energy at the benzyl position is between 295 and 310 kJ / mol, which is significantly higher than that at the β-position of the side chain (250 to 270 kJ / mol). Under the condition of 130℃, the thermal desorption probability of the α-sulfonic acid group is much lower than that of the β-position, thus ensuring the stability of charge density at high temperatures from the perspective of chemical bonds.

[0023] In addition to the main dispersant, this dispersant incorporates 8 to 14 parts by weight of hyperbranched polyglycerol-modified sodium lignosulfonate. This component is a product obtained by grafting sodium lignosulfonate with glycidyl ether as the backbone, with the grafting rate controlled at 15 to 25 wt%. The multiple hydroxyl groups on its dendritic structure can form multi-point hydrogen bonds on the surface of the dye particles for anchoring. Even if some anchoring points break due to thermal motion, the overall adsorption remains firm. This effect is similar to the principle that when an octopus grasps an object, the loosening of a single tentacle does not affect the overall fixation. At the same time, the huge dendritic volume provides a spatial barrier effect that surpasses that of linear polymers.

[0024] To address the unavoidable thermal collapse of organic polymer adsorption layers at high temperatures, this composition incorporates 1 to 3 parts by weight of colloidal silica hydrosol with a particle size of 10 to 15 nm. These nanoparticles form a Pickering-type rigid adsorption layer on the surface of the dye particles. The adsorption energy is much higher than the thermal kinetic energy, making it almost irreversible. Furthermore, the physical barrier it provides does not soften or collapse with increasing temperature. This means that even if the adsorption layer of sodium lignosulfonate and block copolymer weakens at 130°C, the nano-silica shell can still maintain a stable interparticle spacing, preventing particle collision and agglomeration.

[0025] In the selection of nonionic surfactants, this dispersant uses Pluronic F68, which has a triblock structure of polyoxyethylene-polyoxypropylene-polyoxyethylene, instead of traditional fatty alcohol polyoxyethylene ether. The hydrophobicity of the polyoxypropylene segment increases during the heating process, which in turn increases its anchoring force with the hydrophobic surface of the dye as the temperature rises. This is exactly the opposite of the trend of desorption caused by the increased hydrophilicity of sodium lignosulfonate at high temperatures. The two form a temperature compensation effect. Moreover, the low critical dissolution temperature of F68 is above 100℃, and it will not have the problem of precipitation due to reaching the cloud point of conventional nonionic surfactants at 130℃.

[0026] To address the phenomenon of Ostwald curing, which causes dye particles to grow larger while smaller particles shrink at high temperatures, this composition addresses the issue from two angles: reducing the driving force and blocking the growth path. On the one hand, 2 to 4 parts by mass of sodium sulfobutyl ether-β-cyclodextrin with a degree of sulfobutyl substitution of 6 to 7 are added, and the free dye molecules in the supersaturated part of the aqueous phase are contained by its cavity inner diameter of about 6.0 to 6.5 Å, which directly weakens the curing motive force driven by concentration difference. At the same time, the sulfobutyl group on its outer wall also contributes additional negative charge. On the other hand, adding 1 to 2 parts by mass of polyvinylpyrrolidone with a weight-average molecular weight of approximately 8,000 to 15,000 Da allows its lactam groups to selectively adsorb onto the rapid growth surface of the dye crystals and inhibit molecular stacking in that direction. The combination of these two factors achieves a dual inhibition of Ostwald curing by "cutting off the source and blocking the path".

[0027] Regarding the control of environmental factors such as water quality and pH, this dispersant is formulated with 1.5 to 3.5 parts by weight of a graded chelating agent composed of disodium ethylenediaminetetraacetate and sodium citrate. The former preferentially complexes the strongly bound ferric and divalent copper ions in water, while the latter treats the weakly bound calcium and magnesium ions. At the same time, 1 to 3 parts by weight of sodium polyaspartate are added as a biodegradable auxiliary chelating and dispersing dual-function component, which not only supplements the chelating capacity but also partially replaces disodium ethylenediaminetetraacetate to reduce its environmental persistence risk.

[0028] For pH buffering, a combination of disodium hydrogen phosphate and maleic acid is used instead of traditional citric acid buffer because the thermal decomposition temperature of maleic acid is about 135°C, which is significantly better than the slow decomposition of citric acid above 100°C. Under 130°C conditions, maleic acid can more reliably maintain the pH of the dye bath at the range of 5.5 to 6.5, which is most favorable for dispersion stability.

[0029] At the preparation process level, this invention employs a three-liquid stepwise addition method to ensure that each functional component in this dispersant functions at the correct location and timing: First, a mixture of graded sulfonated sodium lignin sulfonate, naphthalene sulfonic acid formaldehyde condensate, sulfonated ketone aldehyde resin, chelating agent, and buffer salt is dissolved in a portion of deionized water at 40 to 50°C to prepare solution A. Solution A and crude dye are fed into a horizontal sand mill for wet grinding, using zirconium beads with a diameter of 0.3 to 0.5 mm as the grinding medium. The grinding speed is gradually increased from an initial linear velocity of 7 to 9 m / s to 11 to 13 m / s. Throughout the process, the slurry temperature is controlled below 45°C by cooling water in the jacket. The particle size is sampled every 25 to 35 minutes until the D90 reaches below 1.0 micrometer twice consecutively before the machine is stopped. After grinding, the material is filtered through a 150 to 250 mesh stainless steel screen to remove any possible zirconium bead fragments.

[0030] Subsequently, hyperbranched polyglycerol-modified sodium lignin sulfonate, Pluronic F68, and sodium polyaspartate were dissolved in another portion of deionized water and prepared into solution B at 35 to 45°C. This solution was then slowly injected into the grinding slurry at 60 to 80 rpm with low-speed stirring. High-speed dispersers are strictly prohibited here to avoid high shear damage to the dendritic structure of hyperbranched lignin and the block configuration of F68.

[0031] Finally, the nano-silica hydrosol, polyvinylpyrrolidone, and sodium sulfobutyl ether-β-cyclodextrin were dissolved in the remaining deionized water to prepare solution C. The nano-silica was added in a strict order: first the nano-silica, then the polyvinylpyrrolidone, and finally the cyclodextrin derivative. This order cannot be changed because the nano-silica needs to contact the dye particles with the existing organic adsorption layer first to form a rigid shell on them rather than competing with other components. The polyvinylpyrrolidone needs to be added after the silica to fill the rapidly growing crystal surface where both the dispersant and silica adsorption are weak. The cyclodextrin derivative mainly functions to encapsulate free dye molecules in the aqueous phase, so adding it last can prevent its cavity from being occupied by molecules of other components added earlier.

[0032] In terms of quality control, the finished product must pass all inspection items, including pH value, particle size distribution D90, Zeta potential, dynamic light scattering particle size, conductivity, and high temperature dispersion stability of not less than 95% after being kept at 130℃ for 90 minutes. The performance deviation coefficient of five consecutive batches is required to be less than 3%.

[0033] Through the combination of the above preparation processes, this dispersant establishes five levels of protection on the surface of dye particles: The first layer is a chemical anchoring layer achieved through multi-point anchoring via α-position sulfonation and hyperbranching; The second layer is an electrostatic repulsion layer provided by four anionic components as redundant negative charge sources; The third layer is a space barrier layer composed of high molecular weight lignin fractions, F68 polyoxyethylene segments, and a nano-silica rigid shell. The fourth layer is a supersaturation regulation and crystal growth inhibition layer achieved by cyclodextrin inclusion and polyvinylpyrrolidone crystal surface adsorption. The fifth layer is an environmental factor control layer composed of tiered chelating agents and high-temperature stable buffer salts.

[0034] These five levels are independent of each other yet complementary. If any single level fails partially due to fluctuations in raw material batches or abnormal operating conditions, the remaining levels can still maintain basic dispersion stability, thus solving the vulnerability problem of "one point failure leading to global collapse" in traditional single-component or simple compounding schemes.

[0035] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A preparation process for a highly stable sodium lignosulfonate dispersant for dyes, comprising the following steps: S1 Raw Material Inspection Steps: Incoming quality inspection of each raw material component is carried out to confirm that key indicators meet control standards. The S2 dispersion preparation step involves dissolving the main components of the dispersant, the chelating agent system, the pH buffer system, and the filler in a portion of deionized water to obtain solution A. In step S3, the A liquid is mixed with the crude dye and then wet-milled until the dye particle size reaches the target value. In step S4, the steric hindrance enhancement and temperature compensation components and the biodegradable chelate-dispersion bifunctional polymer are dissolved in a portion of deionized water to obtain solution B, which is then mixed into the grinding slurry obtained in step S3 by low-speed stirring. In step S5, the supersaturation control and crystal growth inhibition components are dissolved in the remaining deionized water to obtain solution C, which is then mixed into the mixed slurry obtained in step S4 in a specific order using a low-speed stirring method. S6 Finished Product Quality Inspection and Post-Processing Steps: The obtained finished products are inspected for quality, and after confirming that all indicators are qualified, they are packaged or dried.

2. The preparation process of a high-stability sodium lignosulfonate dispersant for dyes according to claim 1, characterized in that, The S1 raw material inspection step involves inspecting the incoming quality of each raw material component to confirm that key indicators meet control standards. This step specifically includes the following steps: S1-1 tested graded sulfonated sodium lignin sulfonate, including the following tests: degree of sulfonation, determined by potentiometric titration, controlled within the range of 1.1-1.7 mmol / g; and the percentage of α-position sulfonation sites, determined by... 13 CNMR or two-dimensional HSQCNMR detection, controlled at ≥60%; molecular weight distribution, detected by gel permeation chromatography, confirming the presence of low molecular weight fractions with a weight average molecular weight of 3000-6000 Da and high molecular weight fractions with a weight average molecular weight of 15000-25000 Da, with a mass ratio of 35:65-45:

55. S1-2 tests the hyperbranched polyglycerol modified sodium lignosulfonate. The test items include: grafting rate, which is detected by TGA thermogravimetric analysis and controlled within 15-25 wt%; water solubility, a 5% aqueous solution should be clear and transparent. S1-3 tested the blend of acetyl sulfonate formaldehyde condensate and sulfonated ketone aldehyde resin and confirmed that the blend mass ratio was 6:4-8:2 and the degree of condensation n of acetyl sulfonate formaldehyde condensate was 5-8. S1-4 tested the polyoxyethylene-polyoxypropylene block copolymer and confirmed its lower critical solution temperature ≥100℃ by cloud point determination. S1-5 was used to test for sodium sulfonyl β-cyclodextrin, using... 1 HNMR was used to determine the degree of sulfobutyl substitution, which was controlled to be 6-7. S1-6 was tested for nano-silica hydrosols. The particle size was determined to be 8-20 nm using dynamic light scattering method, and the solid content was determined to be 25-35 wt% using drying method. S1-7 tested sodium polyaspartate and polyvinylpyrrolidone separately, and confirmed by gel permeation chromatography that the weight average molecular weight of sodium polyaspartate was 3000-5000 Da and the weight average molecular weight of polyvinylpyrrolidone was 8000-15000 Da. S1-8 tests the deionized water using a conductivity meter, controlling the conductivity to be ≤30μS / cm.

3. The preparation process of a high-stability sodium lignosulfonate dispersant for dyes according to claim 1, characterized in that, The preparation step of the S2 dispersion bulk solution involves dissolving the main components of the dispersant, the chelating agent system, the pH buffer system, and the filler in a portion of deionized water to obtain solution A. Specifically, this includes the following steps: S2-1 Add 40-50 parts by weight of deionized water to a stainless steel mixing tank with a heating jacket, turn on the jacket heating to raise the temperature to 40-50℃, turn on the stirring and set the stirring speed to 60-80 rpm. S2-2 Under the temperature conditions of step S2-1, add 25-32 parts by weight of gradient sulfonated sodium lignin sulfonate in batches, with each addition not exceeding 1 / 4 of the total amount. Add the next batch after the previous batch has basically dissolved. Increase the stirring speed to 100-120 rpm. After all the ingredients have been added, continue stirring for 25-35 minutes until completely dissolved. S2-3 After step S2-2 is completed, add 10-15 parts by weight of the blend of acetylene sulfonic acid formaldehyde condensate and sulfonated ketone aldehyde resin. The addition rate is controlled at 2-6 kg / min, and the stirring speed is maintained at 100-120 rpm. After the addition is completed, continue stirring for 15-25 minutes until completely dissolved. S2-4 After step S2-3 is completed, add 1-2 parts by weight of disodium ethylenediaminetetraacetate and 0.5-1.5 parts by weight of sodium citrate in sequence. Stir for 8-12 minutes after each addition until completely dissolved, with a stirring speed of 80-100 rpm. Disodium ethylenediaminetetraacetate must be added before sodium citrate. After step S2-4 is completed, add 0.5-1.0 parts by weight of disodium hydrogen phosphate, stir for 3-8 minutes, then slowly add 0.5-1.0 parts by weight of maleic acid, stir for 8-12 minutes, and check the pH value of solution A to control it at 5.5-6.5; S2-6 After step S2-5 is completed, add 1-4 parts by weight of sodium sulfate, stir for 8-12 minutes, and check the conductivity of solution A to be ≤40μS / cm to obtain solution A.

4. The preparation process of a high-stability sodium lignosulfonate dispersant for dyes according to claim 1, characterized in that, The S3 wet milling step involves mixing the A solution with the crude dye and then performing wet milling until the dye particle size reaches the target value. Specifically, this includes the following steps: S3-1 Pre-dispersion: Mix the A liquid and the crude dye in a slurry tank according to the formula ratio, and pre-dispersion for 8-12 minutes using a high-speed disperser at a linear velocity ≥18m / s to obtain a uniform slurry; S3-2 Grinding: The slurry is fed into a horizontal sand mill for wet grinding. The horizontal sand mill uses 0.3-0.5mm diameter beads as grinding media, with a bead filling rate of 70-80%. The volume ratio of slurry to beads is 1:1.5-1:

2. The grinding speed is controlled in stages. The initial stage linear velocity is 7-9m / s, and after running for 10-20 minutes, it is gradually increased to 11-13m / s. During the grinding process, the slurry temperature is controlled to ≤45℃ by circulating cooling water in the jacket. An external circulation continuous grinding mode is adopted. S3-3 Process Monitoring: During the grinding process, samples are taken every 25-35 minutes. The D90 particle size is detected using a laser particle size analyzer. At the same time, the slurry viscosity is monitored and controlled at 200-500 mPa·s. When the viscosity exceeds 500 mPa·s, deionized water is added to adjust it. S3-4 Endpoint Judgment: When two consecutive sampling tests show D90≤1.0μm, the grinding is deemed qualified; S3-5 Filtration: After grinding, the slurry is filtered through a 150-250 mesh stainless steel screen to remove noreite fragments and coarse particles. The filtrate is then transferred to an intermediate storage tank.

5. The preparation process of a high-stability sodium lignosulfonate dispersant for dyes according to claim 1, characterized in that, The S4 functional additive solution preparation and mixing step involves dissolving the steric hindrance enhancement and temperature compensation components and the biodegradable chelate-dispersion bifunctional polymer in a portion of deionized water to obtain solution B, which is then mixed into the grinding slurry obtained in step S3 using a low-speed stirring method. Specifically, this includes the following steps: S4-1 Add 15-25 parts by weight of deionized water to the second stainless steel mixing tank, turn on the jacket to heat to 35-45℃, and stir at 50-70 rpm. S4-2 Slowly add 8-14 parts by weight of hyperbranched polyglycerol modified sodium lignosulfonate, increase the stirring speed to 80-100 rpm, and stir for 25-35 minutes until completely dissolved, during which the dissolution temperature shall not exceed 55℃; S4-3 After step S4-2 is completed, add the polyoxyethylene-polyoxypropylene block copolymer, maintain the stirring speed at 70-90 rpm, and stir for 12-25 minutes until completely dissolved; After step S4-3 is completed, add 1-3 parts by weight of sodium polyaspartate and stir for 8-12 minutes until completely dissolved to obtain solution B. S4-5 Slowly inject liquid B into the slurry obtained in step S3. The injection speed is controlled at 8-15 kg / min and the mixing speed is 60-80 rpm. After the full amount is injected, continue mixing for 15-25 minutes. It is strictly forbidden to use a high-speed disperser when mixing liquid B; only low-speed mixing is used. After the S4-6B solution was mixed in, the dynamic light scattering particle size of the clear liquid portion of the formula was measured to be <50nm and the Zeta potential was ≤-35mV.

6. The preparation process of a high-stability sodium lignosulfonate dispersant for dyes according to claim 1, characterized in that, The S5 step of preparing and mixing the control component solution involves dissolving the supersaturation control and crystal growth inhibition components in the remaining deionized water to obtain solution C, which is then mixed into the mixed slurry obtained in step S4 in a specific order using a low-speed stirring method. Specifically, this includes the following steps: S5-1 Add 7-12 parts by weight of the remaining deionized water to the third stainless steel mixing tank, stir at room temperature, and stir at a speed of 50-70 rpm. First, add 1-3 parts by weight of nano-silica hydrosol to S5-2 and stir for 8-12 minutes to disperse it evenly. S5-3 Then add 1-2 parts by weight of polyvinylpyrrolidone and stir for 12-18 minutes until completely dissolved; Finally, add 2-4 parts by weight of sodium sulfobutyl β-cyclodextrin salt to S5-4, stir for 15-25 minutes until completely dissolved, and obtain solution C; S5-5 Slowly inject liquid C into the mixed slurry obtained in step S4, controlling the injection speed at 6-10 kg / min and the stirring speed at 60-80 rpm. After the full amount is injected, continue stirring for 25-35 minutes.

7. The preparation process of a high-stability sodium lignosulfonate dispersant for dyes according to claim 1, characterized in that, The S6 finished product quality inspection and post-processing step involves inspecting the obtained finished product to ensure that all indicators are qualified before packaging or drying. Specifically, this includes the following steps: S6-1 conducts quality inspection on the obtained finished product. The inspection items include: pH value controlled between 5.5 and 6.5, measured directly with a pH meter; particle size distribution D90 ≤ 1.0 μm, detected using a laser particle size analyzer; Zeta potential ≤ -35 ​​mV, detected using a Zeta potential analyzer; dynamic light scattering particle size of the clear liquid portion < 50 nm; conductivity ≤ 30 μS / cm; high-temperature dispersion stability not less than 95% after being flattened at 130℃ for 90 minutes, detected using a combination of tube sealing and centrifugal sedimentation. The test method for the high temperature dispersion stability of S6-2 is as follows: after diluting the finished product according to the actual dyeing concentration, put it into a sealed tube, place it in a constant temperature bath at 130℃ for 90 minutes, take it out and let it cool naturally to room temperature, centrifuge at 2500-3500rpm for 25-35 minutes, measure the absorbance of the supernatant and compare it with the unheated control sample, and calculate the stability percentage. For products supplied in liquid form, S6-3 should be directly filled and sealed, and stored at 5-30℃ in the dark. For products supplied in powder form, spray drying should be used, with the inlet temperature controlled at 180-200℃ and the outlet temperature controlled at 70-80℃. The moisture content of the powder product should be ≤5%. After drying, the high-temperature dispersion stability should be retested to confirm that there is no performance degradation.

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