Preparation method of multi-component composite triazinyl stilbene fluorescent whitening agent

Abstract

The invention relates to the field of chemical organic synthesis, in particular to a preparation method of a multi-component composite triazinyl stilbene type fluorescent whitening agent, which specifically comprises the following steps: adding cyanuric chloride into water for pulping, adding a complexing agent for complexing metal ions, dropwise adding DSD acid for reacting with cyanuric chloride, adding an acid-binding agent for maintaining the reaction pH, adding aniline for substitution, and then adding triazinyl stilbene type fluorescent whitening agent to obtain the multi-component composite triazinyl stilbene type fluorescent whitening agent. Then diethanol amine and 6-aminocaproic acid are added in sequence to replace chlorine atoms respectively, generation of by-products is reduced, through compounding of the diethanol amine and the 6-aminocaproic acid, hydrophilic groups are introduced, the whiteness and the retention rate of the product are greatly improved, use of a stabilizer in the product is reduced, the affinity of the product to fibers is improved, and the product quality is improved. And the applicability of the product is widened. Finally, sodium citrate is added for competitive complexing of Ca < 2 + >, Mg < 2 + > and fatty acid polyoxyethylene ether-9 to form a protective layer, Ca < 2 + > and Mg < 2 + > are prevented from making contact with carboxylate radicals, and the problem of hard water sensitivity caused by introduction of 6-aminocaproic acid into the product is solved.

Description

Technical Field

[0001] This invention belongs to the field of chemical organic synthesis, specifically a method for preparing a multi-component composite triazine stilbene fluorescent whitening agent. Background Technology

[0002] Disulfonic acid fluorescent whitening agents are widely used in the papermaking industry due to their unique molecular structure and good binding ability to fibers. However, among traditional single-structure whitening agents, ordinary disulfonic acid has a good whitening effect but requires a large amount of stabilizer to ensure its stability. Low-urea disulfonic acid has a relatively low stabilizer content, but its surface retention rate is lower than that of ordinary disulfonic acid, resulting in a slightly inferior whitening effect. CN103421346A reports a disulfonic acid liquid fluorescent whitening agent and its preparation method. It is synthesized from cyanuric chloride, DSD acid, aniline, and the addition product of acrylic acid and glycine through a three-step condensation reaction, and then desalted by nanofiltration. However, the addition reaction of acrylic acid and glycine produces a large number of byproducts, which has a certain impact on the quality of the product, and acrylic acid has certain hazards.

[0003] Currently, composite fluorescent whitening agents still face many challenges. First, most products require the addition of stabilizers, which leads to an increase in ammonia nitrogen content in papermaking wastewater, causing significant difficulties in subsequent wastewater treatment and resulting in high production costs. Second, the products have limited applicability to different fibers, and fluorescence quenching easily occurs at higher concentrations, leading to high consumption per unit. Finally, the products are sensitive to water hardness, especially after the introduction of hydrophilic groups such as carboxyl groups into the molecule, which easily form precipitates with calcium and magnesium ions, affecting application performance and causing stains. Therefore, these factors greatly limit the development and widespread application of composite fluorescent whitening agents. Summary of the Invention

[0004] (1) Technical problems to be solved The purpose of this invention is to provide a method for preparing a multi-component composite triazine stilbene fluorescent whitening agent, in order to solve the problem of composite fluorescent whitening agents. By improving the raw material ratio, a novel whitening agent structure is designed to achieve the purpose of improving whiteness and reducing the use of product stabilizers.

[0005] (2) Technical solution To achieve the above objectives, on the one hand, the present invention provides a method for preparing a multi-component composite triazine-stilbene fluorescent whitening agent, the method comprising the following steps: S1. Add cyanuric chloride solid to water and slurry it. Add a complexing agent to complex the metal ions, add DSD acid dropwise, and add an acid-binding agent to maintain the reaction pH. Keep the temperature to obtain the first compound. S2. Add aniline to the first compound, adjust the pH with an acid-binding agent, and keep warm to obtain the second compound; S3. Add diethanolamine to the second compound, heat to 80-90℃ and react for 1-2 hours, add 6-aminohexanoic acid and heat to 110-130℃, add an acid-binding agent to maintain pH between 9 and 10, keep warm, and obtain the third compound. S4. Dissolve sodium citrate and fatty acid polyoxyethylene ether-9 in warm water to obtain a mixture. Cool the third compound to 60-70℃, slowly add it to the mixture, keep warm and stir, nanofilter, concentrate, and obtain triazine stilbene type composite fluorescent whitening agent.

[0006] Furthermore, the reaction temperature during the addition of DSD acid in S1 is 0-10°C, preferably 5-6°C; The heat preservation temperature in S1 is 5-20℃, preferably 6-15℃; The temperature at which aniline is added in S2 is 10-25°C, preferably 15-20°C; The insulation temperature in S2 is 25-45℃, preferably 30-35℃.

[0007] Furthermore, the acid-binding agent in S1 is selected from one or more of pyridine, triethylamine, soda ash, and liquid alkali.

[0008] Furthermore, the complexing agent in S1 is selected from one or more of ethylenediaminetetraacetic acid, citrate, pyrophosphate, thiosulfate, polyethylene glycol or methylpyrrolidone, and the amount used is 1-1.5% of the mass of cyanuric chloride.

[0009] Furthermore, the mass ratio of cyanuric chloride to DSD acid in S1 is 0.75-1.05:1.

[0010] Furthermore, the acid-binding agent in S2 is selected from one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, or potassium hydroxide.

[0011] Furthermore, the mass ratio of aniline to the first compound in S2 is 0.23-0.27:1.

[0012] Furthermore, the mass ratio of diethanolamine, 6-aminohexanoic acid, and the second compound in S3 is 0.10-0.15:0.12-0.17:1.

[0013] Furthermore, the amount of sodium citrate S4 added is 1-1.2% of the third compound, and the amount of fatty acid polyoxyethylene ether-9 added is 1-1.5% of the third compound.

[0014] Furthermore, in step S4, a nanofiltration membrane is used for desalination. The nanofiltration membrane has a molecular weight cutoff of 400-600 Da, an operating pressure of 0.8-1.5 MPa, and a temperature of 25-40°C. The solution is concentrated to a solid content of 25-40%, preferably 30-35%.

[0015] Traditional whitening agents typically employ cyanuric chloride, DSD acid, and single amine substituents, resulting in limited performance and an inability to achieve both whitening effect and stability. In contrast, this invention utilizes cyanuric chloride, DSD acid, diethanolamine substituents, and 6-aminocaproic acid substituents to achieve complementary functions and synergistic performance.

[0016] First, the -NH(CH2CH2OH)2 group in the diethanolamine molecule provides two hydroxyl groups to form intramolecular and intermolecular hydrogen bonds with the carboxyl group and the triazine ring, respectively, thereby stabilizing the molecular structure and reducing aggregation. Furthermore, the hydroxyethyl group is a strong hydrophilic group; when it replaces the chlorine atom on the triazine ring, it significantly improves the solubility and dispersibility of the entire whitening agent molecule in water. Simultaneously, the steric hindrance of the hydroxyl group prevents excessive molecular stacking, reducing dependence on stabilizers. This allows the hydroxyl group to partially replace the stabilizing effect of urea, significantly reducing the use of stabilizers. Second, the carboxyl group of 6-aminohexanoic acid forms a hydrogen bond network with the hydroxyl group of cellulose, achieving multi-point adsorption. Moreover, the long-chain alkane structure of 6-aminohexanoic acid forms a flexible "spacer arm" between the carboxyl group and the triazine ring. This flexible chain can embed into the hydrophobic region of the fiber, enhancing van der Waals forces and improving retention. Diethanolamine and 6-aminohexanoic acid work synergistically. On one hand, the -OH group of diethanolamine donates electrons, while the -COOH group of 6-aminohexanoic acid withdraws electrons, forming a push-pull electron system that enhances the conjugation effect, increases the fluorescence quantum yield, and prevents aggregation by the amphiphilic groups, reducing fluorescence self-quenching and improving single-molecule luminescence efficiency, thus enhancing the product's color and whiteness. On the other hand, the product forms a dual anchoring with the fiber. The hydroxyl groups of diethanolamine quickly cover the fiber surface, and the long chains of 6-aminohexanoic acid enter the fiber pores, resulting in a whitening agent distribution in both the inner and outer layers, leading to more uniform whiteness. Finally, the aromatic ring of aniline provides moderate hydrophobicity to balance the strong hydrophilicity of diethanolamine and 6-aminohexanoic acid, preventing excessive hydrophilicity that could cause slippage on the fiber surface and improving retention.

[0017] However, the introduction of carboxyl groups makes the product extremely sensitive to water hardness, particularly in hard water rich in Ca. 2+ Mg 2+ Plasma and carboxylate ions readily form insoluble salts with these metal ions, leading to turbidity or even precipitation in the whitening agent working solution, significantly reducing whitening efficiency. When applied to fabrics or paper, they can also cause stains. Therefore, sodium citrate and fatty acid polyoxyethylene ether-9 must be added after the reaction. Citrate ions react with Ca... 2+ Mg 2+These ions possess extremely high complexation stability constants, far exceeding those of carboxylate ions. When encountering hard water, they preferentially combine with hardness ions in the water to form stable, water-soluble complexes, thereby preventing Ca2+ from being absorbed. 2+ Mg 2+ Carboxylate group contact on the whitening agent. Fatty acid polyoxyethylene ether-9 has long-chain alkyl groups and polyoxyethylene chains. Its long-chain alkyl groups are hydrophobic and adsorb onto the hydrophobic backbone of the whitening agent (such as triazine rings and stilbene) through van der Waals forces, while the polyoxyethylene chains are hydrophilic and extend into the water, forming a hydrated, dense polymer protective layer. This protective layer generates a steric hindrance effect, which not only shields metal ions and prevents them from contacting the carboxylate groups, but also inhibits molecular aggregation, thereby improving the storage stability and dispersibility of the product.

[0018] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are: 1. By combining diethanolamine with 6-aminohexanoic acid, hydrophilic hydroxyl and carboxyl groups are introduced, which not only greatly improves the whiteness and retention of the product, but also reduces the use of stabilizers in the product, improves the product's affinity for fibers, and broadens the product's applicability.

[0019] 2. Sodium citrate competitively complexes with Ca. 2+ Mg 2+ Fatty acid polyoxyethylene ether-9 forms a protective layer, preventing Ca from forming. 2+ Mg 2+ By contacting the carboxylate group, a dual physical and chemical protection mechanism is constructed to solve the problem of hard water sensitivity caused by the introduction of 6-aminohexanoic acid into the product.

[0020] 3. This invention reduces the generation of byproducts and improves product yield and purity by adding diethanolamine and 6-aminohexanoic acid in steps. In addition, the amount of stabilizer added to the final product is reduced, which reduces the difficulty of subsequent wastewater treatment and thus reduces production costs. Attached Figure Description

[0021] Figure 1 This is a flowchart illustrating the preparation process of the triazine-stilbene composite fluorescent whitening agent of the present invention. Detailed Implementation

[0022] 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. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0023] Example 1: This example discloses a method for preparing a multi-component composite triazine-stilbene fluorescent whitening agent, characterized in that the method includes the following steps: S1. Add 18.44g of cyanuric chloride solid to water and slurry for 60min. Add 0.25g of ethylenediaminetetraacetic acid to complex metal ions. Cool the reaction system to 5-6℃ with stirring. Slowly add 17.78g of DSD acid and add sodium carbonate to maintain the reaction pH at 5.5-6.5. Keep the temperature at 6-15℃ for 2-4h to obtain the first compound. S2. Add 9.3g of aniline to 38g of the first compound, control the feeding temperature at 15-20℃, adjust the pH to 8-9 with sodium carbonate, and keep warm at 30-35℃ for 1h to obtain the second compound; S3. Add 2.63g of diethanolamine to 22g of the second compound, heat to 80-90℃ and react for 1-2h, add 3.3g of 6-aminohexanoic acid and heat to 110-130℃ at 0.2-0.4MPa, add sodium hydroxide solution to maintain pH between 9.5-10.5, keep warm for 4-6h to obtain the third compound; S4. Dissolve sodium citrate (1.1% of the mass of the third compound) and fatty acid polyoxyethylene ether-9 (1.2% of the mass of the third compound) in warm water at 50-60℃ to obtain a mixture. Cool the third compound to 60-70℃ and slowly add it to the mixture. Keep it at 60-70℃ and stir for 30 minutes. Desalinate using a nanofiltration membrane with a molecular weight cutoff of 400-600 Da at an operating pressure of 0.8-1.5 MPa and a temperature of 25-40℃. Vacuum concentrate to a solid content of 30-35% to obtain a triazine-stilbene type composite fluorescent whitening agent.

[0024] It should be noted that, as Figure 1 The diagram shows the preparation process of triazine-stilbene composite fluorescent whitening agent. Due to the simultaneous introduction of diethanolamine and 6-aminohexanoic acid, it is possible that the two chlorine atoms of the second compound may be replaced by either diethanolamine or 6-aminohexanoic acid. However, the target product requires one chlorine atom to be replaced by diethanolamine and one chlorine atom to be replaced by 6-aminohexanoic acid. Therefore, it is necessary to control the reaction order to maximize the yield of the target product. That is, first add diethanolamine and react at 80-90℃ for 2 hours to preferentially replace one chlorine atom, and then add 6-aminohexanoic acid at a higher temperature to replace the remaining chlorine atom.

[0025] Example 2: This example discloses a method for preparing a multi-component composite triazine-stilbene fluorescent whitening agent, characterized in that the method includes the following steps: S1. Add 18.44g of cyanuric chloride solid to water and slurry for 60min. Add 0.20g of ethylenediaminetetraacetic acid to complex metal ions. Cool the reaction system to 5-6℃ with stirring. Slowly add 21.69g of DSD acid and add sodium carbonate to maintain the reaction pH at 5.5-6.5. Keep the temperature at 6-15℃ for 2-4h to obtain the first compound. S2. Add 9.3g of aniline to 38g of the first compound, control the feeding temperature at 15-20℃, adjust the pH to 8-9 with sodium carbonate, and keep warm at 30-35℃ for 1h to obtain the second compound; S3. Add 2.63g of diethanolamine to 22g of the second compound, heat to 80-90℃ and react for 1-2h, add 3.3g of 6-aminohexanoic acid and heat to 110-130℃ at 0.2-0.4MPa, add sodium hydroxide solution to maintain pH between 9.5-10.5, keep warm for 4-6h to obtain the third compound; S4. Dissolve sodium citrate (1.1% of the mass of the third compound) and fatty acid polyoxyethylene ether-9 (1.2% of the mass of the third compound) in warm water at 50-60℃ to obtain a mixture. Cool the third compound to 60-70℃ and slowly add it to the mixture. Keep it at 60-70℃ and stir for 30 minutes. Desalinate using a nanofiltration membrane with a molecular weight cutoff of 400-600 Da at an operating pressure of 0.8-1.5 MPa and a temperature of 25-40℃. Vacuum concentrate to a solid content of 30-35% to obtain a triazine-stilbene type composite fluorescent whitening agent.

[0026] Example 3: This example discloses a method for preparing a multi-component composite triazine-stilbene fluorescent whitening agent, characterized in that the method includes the following steps: S1. Add 18.44g of cyanuric chloride solid to water and slurry for 60min. Add 0.25g of ethylenediaminetetraacetic acid to complex metal ions. Cool the reaction system to 5-6℃ with stirring. Slowly add 17.78g of DSD acid and add sodium carbonate to maintain the reaction pH at 5.5-6.5. Keep the temperature at 6-15℃ for 2-4h to obtain the first compound. S2. Add 9.3g of aniline to 34.5g of the first compound, control the feeding temperature at 15-20℃, adjust the pH to 8-9 with sodium carbonate, and keep warm at 30-35℃ for 1h to obtain the second compound; S3. Add 2.63g of diethanolamine to 22g of the second compound, heat to 80-90℃ and react for 1-2h, add 3.3g of 6-aminohexanoic acid and heat to 110-130℃ at 0.2-0.4MPa, add sodium hydroxide solution to maintain pH between 9.5-10.5, keep warm for 4-6h to obtain the third compound; S4. Dissolve sodium citrate (1.1% of the mass of the third compound) and fatty acid polyoxyethylene ether-9 (1.2% of the mass of the third compound) in warm water at 50-60℃ to obtain a mixture. Cool the third compound to 60-70℃ and slowly add it to the mixture. Keep it at 60-70℃ and stir for 30 minutes. Desalinate using a nanofiltration membrane with a molecular weight cutoff of 400-600 Da at an operating pressure of 0.8-1.5 MPa and a temperature of 25-40℃. Vacuum concentrate to a solid content of 30-35% to obtain a triazine-stilbene type composite fluorescent whitening agent.

[0027] Example 4: This example discloses a method for preparing a multi-component composite triazine-stilbene fluorescent whitening agent, characterized in that the method includes the following steps: S1. Add 18.44g of cyanuric chloride solid to water and slurry for 60min. Add 0.25g of ethylenediaminetetraacetic acid to complex metal ions. Cool the reaction system to 5-6℃ with stirring. Slowly add 17.78g of DSD acid and add sodium carbonate to maintain the reaction pH at 5.5-6.5. Keep the temperature at 6-15℃ for 2-4h to obtain the first compound. S2. Add 9.3g of aniline to 38g of the first compound, control the feeding temperature at 15-20℃, adjust the pH to 8-9 with sodium carbonate, and keep warm at 30-35℃ for 1h to obtain the second compound; S3. Add 2.63g of diethanolamine to 26.3g of the second compound, heat to 80-90℃ and react for 1-2h, add 3.16g of 6-aminohexanoic acid and heat to 110-130℃ at 0.2-0.4MPa, add sodium hydroxide solution to maintain pH between 9.5-10.5, keep warm for 4-6h to obtain the third compound; S4. Dissolve sodium citrate (1.1% of the mass of the third compound) and fatty acid polyoxyethylene ether-9 (1.2% of the mass of the third compound) in warm water at 50-60℃ to obtain a mixture. Cool the third compound to 60-70℃ and slowly add it to the mixture. Keep it at 60-70℃ and stir for 30 minutes. Desalinate using a nanofiltration membrane with a molecular weight cutoff of 400-600 Da at an operating pressure of 0.8-1.5 MPa and a temperature of 25-40℃. Vacuum concentrate to a solid content of 30-35% to obtain a triazine-stilbene type composite fluorescent whitening agent.

[0028] Example 5: This example discloses a method for preparing a multi-component composite triazine-stilbene fluorescent whitening agent, characterized in that the method includes the following steps: S1. Add 18.44g of cyanuric chloride solid to water and slurry for 60min. Add 0.25g of ethylenediaminetetraacetic acid to complex metal ions. Cool the reaction system to 5-6℃ with stirring. Slowly add 17.78g of DSD acid and add sodium carbonate to maintain the reaction pH at 5.5-6.5. Keep the temperature at 6-15℃ for 2-4h to obtain the first compound. S2. Add 9.3g of aniline to 38g of the first compound, control the feeding temperature at 15-20℃, adjust the pH to 8-9 with sodium carbonate, and keep warm at 30-35℃ for 1h to obtain the second compound; S3. Add 2.63g of diethanolamine to 17.5g of the second compound, heat to 80-90℃ and react for 1-2h, add 3.0g of 6-aminohexanoic acid and heat to 110-130℃ at 0.2-0.4MPa, add sodium hydroxide solution to maintain pH between 9.5-10.5, and keep warm for 4-6h to obtain the third compound; S4. Dissolve sodium citrate (1.1% of the mass of the third compound) and fatty acid polyoxyethylene ether-9 (1.2% of the mass of the third compound) in warm water at 50-60℃ to obtain a mixture. Cool the third compound to 60-70℃ and slowly add it to the mixture. Keep it at 60-70℃ and stir for 30 minutes. Desalinate using a nanofiltration membrane with a molecular weight cutoff of 400-600 Da at an operating pressure of 0.8-1.5 MPa and a temperature of 25-40℃. Vacuum concentrate to a solid content of 30-35% to obtain a triazine-stilbene type composite fluorescent whitening agent.

[0029] Example 6: This example discloses a method for preparing a multi-component composite triazine-stilbene fluorescent whitening agent, characterized in that the method includes the following steps: S1. Add 18.44g of cyanuric chloride solid to water and slurry for 60min. Add 0.25g of ethylenediaminetetraacetic acid to complex metal ions. Cool the reaction system to 5-6℃ with stirring. Slowly add 17.78g of DSD acid and add sodium carbonate to maintain the reaction pH at 5.5-6.5. Keep the temperature at 6-15℃ for 2-4h to obtain the first compound. S2. Add 9.3g of aniline to 38g of the first compound, control the feeding temperature at 15-20℃, adjust the pH to 8-9 with sodium carbonate, and keep warm at 30-35℃ for 1h to obtain the second compound; S3. Add 2.63g of diethanolamine to 22g of the second compound, heat to 80-90℃ and react for 1-2h, add 3.3g of 6-aminohexanoic acid and heat to 110-130℃ at 0.2-0.4MPa, add sodium hydroxide solution to maintain pH between 9.5-10.5, keep warm for 4-6h to obtain the third compound; S4. Dissolve sodium citrate (1.5% of the mass of the third compound) and fatty acid polyoxyethylene ether-9 (1.5% of the mass of the third compound) in warm water at 50-60℃ to obtain a mixture. Cool the third compound to 60-70℃ and slowly add it to the mixture. Keep it at 60-70℃ and stir for 30 minutes. Desalinate using a nanofiltration membrane with a molecular weight cutoff of 400-600 Da at an operating pressure of 0.8-1.5 MPa and a temperature of 25-40℃. Vacuum concentrate to a solid content of 30-35% to obtain a triazine-stilbene type composite fluorescent whitening agent.

[0030] Comparative Example 1: This comparative example is based on Example 1, but differs from Example 1 in that 6-aminohexanoic acid is added first, followed by diethanolamine, during the preparation process described in this comparative example.

[0031] A method for preparing a multi-component composite triazine-stilbene fluorescent whitening agent, characterized in that the method includes the following steps: S1. Add cyanuric chloride solid to water and slurry for 60 min. Add a complexing agent to complex metal ions, add DSD acid dropwise, and add an acid-binding agent to maintain the reaction pH at 3-4. Keep warm for 1.5 h to obtain the first compound. S2. Add aniline to the first compound, adjust the pH to 8-9 using an acid-binding agent, and keep warm for 1 hour to obtain the second compound; S3. Add 6-aminohexanoic acid to the second compound, heat to 80-90℃ and react for 2 hours, add diethanolamine and heat to 110-130℃, add an acid-binding agent to maintain pH between 9 and 10, keep warm for 3 hours, and obtain the third compound. S4. Dissolve sodium citrate and fatty acid polyoxyethylene ether-9 in warm water to obtain a mixture. Cool the third compound to 60-70℃, slowly add it to the mixture, keep warm and stir for 30 minutes, nanofilter, concentrate, and obtain triazine stilbene type composite fluorescent whitening agent.

[0032] Comparative Example 2: This comparative example is based on Example 1, but differs from Example 1 in that 6-aminohexanoic acid and diethanolamine are added simultaneously during the preparation process of this comparative example.

[0033] S1. Add cyanuric chloride solid to water and slurry for 60 min. Add a complexing agent to complex metal ions, add DSD acid dropwise, and add an acid-binding agent to maintain the reaction pH at 3-4. Keep warm for 1.5 h to obtain the first compound. S2. Add aniline to the first compound, adjust the pH to 8-9 using an acid-binding agent, and keep warm for 1 hour to obtain the second compound; S3. Diethanolamine and 6-aminohexanoic acid were added to the second compound, the temperature was raised to 80-90℃, an acid-binding agent was added to maintain the pH between 9 and 10, and the temperature was maintained for 3 hours to obtain the third compound. S4. Dissolve sodium citrate and fatty acid polyoxyethylene ether-9 in warm water to obtain a mixture. Cool the third compound to 60-70℃, slowly add it to the mixture, keep warm and stir for 30 minutes, nanofilter, concentrate, and obtain triazine stilbene type composite fluorescent whitening agent.

[0034] The other components and preparation methods are the same as in Example 1.

[0035] Comparative Example 3: This comparative example is based on Example 1, but unlike Example 1, 6-aminohexanoic acid is not added.

[0036] The other components and preparation methods are the same as in Example 1.

[0037] Comparative Example 4: This comparative example is based on Example 1, but unlike Example 1, diethanolamine is not added to this comparative example.

[0038] The other components and preparation methods are the same as in Example 1.

[0039] Comparative Example 5: This comparative example is based on Example 1, but unlike Example 1, sodium citrate is not added.

[0040] The other components and preparation methods are the same as in Example 1.

[0041] Comparative Example 6: This comparative example is based on Example 1, but unlike Example 1, this comparative example does not contain fatty acid polyoxyethylene ether-9.

[0042] The other components and preparation methods are the same as in Example 1.

[0043] Experimental verification: Experiment 1: Whitening effect (1) Fluorescence intensity: The products prepared in the examples and comparative examples were prepared into an aqueous solution of 0.01%wt, and the maximum fluorescence emission intensity was measured using a fluorescence spectrophotometer at an excitation wavelength of 350nm.

[0044] (2) Standard whiteness: Apply 0.1% (owf, by weight of paper) of whitening agent to standard paper and measure the whiteness value ISO using a whiteness meter.

[0045] (3) Retention rate: Prepare a 1% concentration pulp suspension, stir evenly, add whitening agent, stir at 500 rpm for 15 minutes to ensure full mixing and adsorption, add an appropriate amount of CPAM solution, stir slowly for 1 minute, use Buchner funnel for vacuum filtration, collect wet paper sheets, dry, and measure its whiteness value with a whiteness meter.

[0046]

[0047] Table 1 shows the whitening effect of the triazine-stilbene type fluorescent whitening agent. Compared with Comparative Examples 1 and 3, Example 1 has better maximum fluorescence intensity and standard whiteness value, indicating that it has higher fluorescence efficiency and whitening potential. Example 1 also has a higher whiteness value; at the same addition amount, higher whiteness indirectly indicates that more whitening agent remains on the fiber. Therefore, it can be seen that Example 1 in this invention has a relatively better whitening effect.

[0048] Experiment 2: Stability Test (1) Thermal storage stability: The samples prepared in the examples and comparative examples were placed in a constant temperature oven at 50°C and aged for 7 days. The separation and precipitation were observed, and the whiteness performance retention rate before and after aging was tested.

[0049] (2) Hard water stability: The products prepared in the examples and comparative examples were prepared into a 0.1% whitening agent solution using high-hardness water (300 ppm, calculated as CaCO3). After standing for 24 hours, the appearance of the solution was observed and the transmittance of the solution at 550 nm was measured. Paper was treated with a 0.1% (owf) working solution prepared with the above-mentioned hard water, and after drying, the presence of color spots was observed and the whiteness was measured.

[0050]

[0051] Table 2 shows the stability of triazine stilbene fluorescent whitening agents. Comparing Example 1 and Comparative Example 4, it can be seen that the addition of diethanolamine and 6-aminohexanoic acid can significantly improve the stability of the whitening agent. However, 6-aminohexanoic acid makes the product more sensitive to hard water, while the addition of sodium citrate and fatty acid polyoxyethylene ether-9 significantly enhances the product's resistance to hard water.

[0052] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A process for producing a multi-component complex triazine-based bisphenylstilbene-based fluorescent whitening agent, characterized by, The method comprises the following steps: S1. Cyanuric chloride solid is added to water for beating, a complexing agent is added to complex metal ions, DSD acid is added dropwise, an acid-binding agent is added to maintain the pH of the reaction, and the mixture is incubated to obtain a first compound; S2. Aniline is added to the first compound, the pH is adjusted by an acid-binding agent, and the mixture is incubated to obtain a second compound; S3. Diethanolamine is added to the second compound, the temperature is raised to 80-90℃, and the mixture is reacted for 1-2h, 6-aminohexanoic acid is added, the temperature is raised to 110-130℃, an acid-binding agent is added to maintain the pH at 9.5-10.5, and the mixture is incubated to obtain a third compound; S4. Sodium citrate and fatty acid polyoxyethylene ether-9 are dissolved in warm water to obtain a mixed solution, the third compound is cooled to 60-70℃, the mixed solution is slowly added to the third compound, and the mixture is incubated and stirred to obtain a triazine-based distyryl compound fluorescent whitening agent.

2. The preparation method of a multi-component composite triazine-stilbene fluorescent whitening agent according to claim 1, characterized in that, The reaction temperature during the dropwise addition of DSD acid in S1 is 0-10℃, preferably 5-6℃; The incubation temperature in S1 is 5-20℃, preferably 6-15℃; The temperature for the dropwise addition of aniline in S2 is 10-25℃, preferably 15-20℃; The incubation temperature in S2 is 25-45℃, preferably 30-35℃.

3. The preparation method of a multi-component composite triazine-stilbene fluorescent whitening agent according to claim 1, characterized in that, The acid-binding agent in S1 is selected from one or more of pyridine, triethylamine, soda ash, and liquid alkali.

4. The preparation method of a multi-component composite triazine-stilbene fluorescent whitening agent according to claim 1, characterized in that, The complexing agent in S1 is selected from one or more of ethylenediaminetetraacetic acid, citrate, pyrophosphate, thiosulfate, polyethylene glycol, or methylpyrrolidone, and the amount is 1-1.5% of the mass of cyanuric chloride.

5. The preparation method of a multi-component composite triazine-stilbene fluorescent whitening agent according to claim 1, characterized in that, The mass ratio of cyanuric chloride to DSD acid in S1 is 0.75-1.05:

1.

6. The preparation method of a multi-component composite triazine-stilbene fluorescent whitening agent according to claim 1, characterized in that, The acid-binding agent in S2 is selected from one or more of sodium carbonate, sodium bicarbonate, sodium hydroxide, or potassium hydroxide.

7. The preparation method of a multi-component composite triazine-stilbene fluorescent whitening agent according to claim 1, characterized in that, The mass ratio of aniline to the first compound in S2 is 0.23-0.27:

1.

8. The preparation method of a multi-component composite triazine-stilbene fluorescent whitening agent according to claim 1, characterized in that, The mass ratio of diethanolamine, 6-aminohexanoic acid, and the second compound in S3 is 0.10-0.15:0.12-0.17:

1.

9. The preparation method of a multi-component composite triazine-stilbene fluorescent whitening agent according to claim 1, characterized in that, The addition amount of sodium citrate in S4 is 1-1.2% of the third compound, and the addition amount of fatty acid polyoxyethylene ether-9 is 1-1.5% of the third compound.

10. The preparation method of a multi-component composite triazine-stilbene fluorescent whitening agent according to claim 1, characterized in that, Desalination treatment is performed on the product of S4 using a nanofiltration membrane, the nanofiltration membrane has a molecular weight cut-off of 400-600Da, the operating pressure is 0.8-1.5MPa, and the temperature is 25-40℃; the product is concentrated to a solid content of 25-40%, preferably 30-35%.

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