Preparation method of integrated amphoteric wet finishing material with color-changing pH response

Abstract

The present invention discloses a method for preparing an integrated amphoteric wet-finishing material that changes color in response to pH. Specifically, the method comprises: synthesizing an amphoteric polymer (ADL) by free radical polymerization using acrylic acid, dimethyldiallylammonium chloride, and lauryl methacrylate as monomers; grafting rhodamine B-ethylenediamine, aminofluorescein, and aminopyrene onto the amphoteric polymer ADL, and mixing the three polymers to prepare the integrated amphoteric wet-finishing material. Red, green, and blue fluorescent groups are grafted onto the side chains of ADL, and the ratio of the three colors is adjusted using the principle of the addition of three primary colors to obtain an integrated wet-finishing material with different colors. This integrated wet-finishing material can be used to dye leather in a variety of colors. Furthermore, the integrated wet-finishing material effectively reduces the traditional three-step wet-finishing process to a single step, which has far-reaching significance for achieving cleaner production in the leather industry.

Description

Technical Field

[0001] The invention belongs to the technical field of leather chemical preparation, and particularly relates to a method for preparing an integrated amphoteric wet finishing material that can change color in response to pH. Background Art

[0002] The wet finishing stage is a crucial process in the leather manufacturing process. Retanning, fatliquoring, and dyeing have a significant impact on the leather's external feel, physical and mechanical properties, and intrinsic quality. Currently, the wet finishing process is complex, requiring the addition of numerous chemical additives in large quantities, resulting in significant resource consumption (such as electricity, water, and labor costs) and severe environmental pollution. Furthermore, to accommodate chrome-tanned tanning systems, the majority of existing wet finishing materials are anionic, making them incompatible with organic chrome-free tanning systems. Amphoteric polymers offer advantages such as designable molecular structures and on-demand synthesis. Their structures contain both anionic and cationic groups and exhibit pH-responsive properties. By manipulating the anionic-cationic ratio within their molecular structure, the isoelectric point of the amphoteric polymer can be altered, thereby regulating the ratio of positive and negative charges. This allows the synthesis of highly positively charged multifunctional amphoteric wet finishing materials. These materials, upon interaction with a collagen matrix, enhance the positive charge of crust leather, thereby increasing the adsorption and binding capacity for anionic fatliquors and dyes. Furthermore, their added functionality simplifies the wet finishing process.

[0003] Genuine leather products are high-end luxury goods, so developing a green and simple anti-counterfeiting technology is crucial to the healthy development of the leather market. Furthermore, pH is a key parameter in leather pretreatment, primarily affecting the penetration and bonding of chemical additives into leather fibers. Therefore, the application of multifunctional pH-responsive color-changing materials in leather wet finishing processes would not only enable multi-color dyeing of leather but also allow for monitoring pH changes during processing. Summary of the Invention

[0004] The object of the present invention is to provide a method for preparing an integrated amphoteric wet finishing material that can change color in response to pH. The material has a pH-responsive color-changing function and excellent multicolor dyeing function for leather.

[0005] The technical solution adopted by the present invention is a method for preparing an integrated amphoteric wet finishing material that can change color in response to pH, which is specifically implemented according to the following steps:

[0006] Step 1: Using acrylic acid, dimethyldiallylammonium chloride, and lauryl methacrylate as monomers, an amphoteric polymer ADL was synthesized by free radical polymerization;

[0007] Step 2: Rhodamine B-ethylenediamine, aminofluorescein, and aminopyrene are grafted onto the amphoteric polymer ADL respectively, and the three polymers are mixed to prepare an integrated amphoteric wet finishing material.

[0008] The present invention is also characterized in that:

[0009] In step 1, specifically:

[0010] Acrylic acid, dimethyldiallylammonium chloride, and lauryl methacrylate are mixed with anhydrous ethanol to dissolve them, and an initiator azobisisobutyronitrile ethanol solution is added dropwise to carry out a polymerization reaction at a reaction temperature of 60-75°C and a reaction time of 6-9 hours. After the reaction is completed, the reaction solution is placed in anhydrous ethanol and dialyzed using a dialysis bag with a molecular weight of 500 for 24-36 hours to remove unreacted monomers to obtain a pure amphoteric polymer ADL.

[0011] The molar ratio of acrylic acid, dimethyl diallyl ammonium chloride and lauryl methacrylate is 1:2-5:0.5; the amount of initiator azobisisobutyronitrile is 0.5-1.0% of the total weight of acrylic acid, dimethyl diallyl ammonium chloride and lauryl methacrylate.

[0012] In step 2, specifically:

[0013] Step 2.1: The amphoteric polymer ADL was dissolved in anhydrous ethanol, and then N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)-carbodiimide were added to activate the reaction system. After stirring for 30-60 minutes, rhodamine B-ethylenediamine was added and refluxed. After the reaction, the mixed solution was transferred to a dialysis bag and dialyzed against anhydrous ethanol. The solvent was removed by distillation under reduced pressure to obtain a light pink powder ADL-RhB.

[0014] Step 2.2: Dissolve the amphoteric polymer ADL in anhydrous ethanol, then add N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)-carbodiimide to activate the reaction system. After stirring for 30-60 minutes, dissolve aminofluorescein in hot anhydrous ethanol and add it to the ethanol solution of the amphoteric polymer ADL. Reflux the solution. After the reaction is complete, transfer the mixed solution to a dialysis bag, dialyze against anhydrous ethanol, and remove the solvent by distillation under reduced pressure to obtain a pale yellow powder, ADL-FITC.

[0015] Step 2.3: The amphoteric polymer ADL is added to anhydrous ethanol, followed by the addition of N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)-carbodiimide. The reaction is activated for 30 to 60 minutes. Aminopyrene is dissolved in hot anhydrous ethanol and slowly added dropwise to the ethanol solution of the amphoteric polymer ADL. The reaction is refluxed. After completion of the reaction, the mixed solution is dialyzed against anhydrous ethanol and the solvent is removed by distillation under reduced pressure to obtain a dark brown powder, ADL-Py.

[0016] Step 2.4: Dissolve ADL-RhB, ADL-FITC and ADL-Py in pure water respectively, mix the three solutions to obtain a mixed solution, and then adjust the pH of the mixed solution to 3-8. When the pH is 3.0, the mixed solution is light pink; when the pH is 4.0, the mixed solution is pink-purple; when the pH is 5.0, the mixed solution is light green; when the pH is 6.0, the mixed solution is green; when the pH is 7.0, the mixed solution is yellow-green; when the pH is 8.0, the mixed solution is yellow, and an integrated amphoteric wet finishing material with color change controlled by pH can be obtained.

[0017] In step 2.1, the molar ratio of the amphoteric polymer ADL, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)-carbodiimide and rhodamine B-ethylenediamine is 10-15:1.5-2.0:3.0-4.0:1.0-1.5.

[0018] In step 2.2, the molar ratio of the amphoteric polymer ADL, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)-carbodiimide, and aminofluorescein is 10-15:1.5-2.0:3.0-4.0:1.0-1.5.

[0019] In step 2.3, the molar ratio of the amphoteric polymer ADL, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)-carbodiimide, and aminopyrene is 10-15:1.5-2.0:3.0-4.0:1.0-1.5.

[0020] In step 2.1, step 2.2, and step 2.3, the reflux reaction temperature is 60-75° C., the reflux reaction time is 12-36 h, and the dialysis time is 24-36 h.

[0021] In step 2.4, the mass ratio of ADL-RhB, ADL-FITC, and ADL-Py is 5-1:1-2:1-2; the concentrations of the ADL-RhB solution, ADL-FITC solution, and ADL-Py solution are all 0.10-0.15 g / mL.

[0022] The beneficial effects of the present invention are as follows: the amphoteric polymer ADL prepared by the present invention contains anionic groups and cationic groups in its structure, and its charge properties can be adjusted by pH. During the wet finishing process of leather, its electrical properties can be adjusted to promote sufficient penetration and binding in collagen fibers. At the same time, the long alkyl chains in the ADL structure can stretch out the tightly wound collagen fiber bundles, causing relative slip between the fiber bundles, thereby improving the softness of the leather. ADL with a larger molecular weight can be filled in the collagen fibers, binding to the active sites on the collagen fibers, and playing a role in retanning. In addition, red, green, and blue fluorescent groups are grafted onto the side chains of ADL respectively, and the ratio of the three colors is adjusted by the principle of the addition of the three primary colors to obtain a wet finishing integrated material with different colors. The wet finishing integrated material can be used to dye leather to give the leather a variety of colors. In addition, the wet finishing integrated material can effectively simplify the traditional three-step wet finishing process into one step, which is of far-reaching significance for the leather industry to achieve clean production. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a diagram of the synthesis process of the three primary color amphoteric polymers (ADL-RhB, ADL-FITC, ADL-Py) of the present invention;

[0024] Figure 2 The particle size distribution diagram of the three primary color amphoteric polymers (ADL-RhB, ADL-FITC, ADL-Py) of the present invention;

[0025] Figure 3 The molecular weight distribution diagram of the three primary color amphoteric polymers (ADL-RhB, ADL-FITC, ADL-Py) of the present invention;

[0026] Figure 4 Softness graph of leather samples prepared using the integrated amphoteric wet finishing material of Example 1;

[0027] Figure 5 Graph showing the thickening rate of leather samples prepared using the integrated amphoteric wet finishing material of Example 1;

[0028] Figure 6 This is a graph showing the surface color change of a leather sample dyed with the integrated amphoteric wet finishing material of Example 1 under visible light and ultraviolet light as the pH changes;

[0029] Figure 7 Dyeing uniformity test chart for leather dyed with integrated amphoteric wet finishing materials of different pH values;

[0030] Figure 8 This is a test chart showing the wet and dry rubbing resistance of leather dyed with integrated amphoteric wet finishing materials at different pH levels;

[0031] Figure 9Leather anti-counterfeiting patterns prepared for leather dyed with integrated amphoteric wet finishing materials at different pH levels. DETAILED DESCRIPTION

[0032] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] The preparation method of the pH-responsive color-changing integrated amphoteric wet finishing material of the present invention is specifically implemented according to the following steps:

[0034] Step 1: Synthesis of amphoteric polymer: Using acrylic acid (AA), dimethyldiallylammonium chloride (DMDAAC), and lauryl methacrylate (LMA) as basic monomers, the amphoteric polymer poly(AA-co-DMDAAC-co-LMA), abbreviated as ADL, was synthesized by free radical polymerization.

[0035] Specifically, acrylic acid, dimethyldiallylammonium chloride, and lauryl methacrylate are mixed with anhydrous ethanol to dissolve them, and an initiator azobisisobutyronitrile (AIBN) ethanol solution is added dropwise to carry out a polymerization reaction. After the reaction is completed, the reaction solution is placed in anhydrous ethanol and dialyzed using a dialysis bag with a molecular weight of 500 for 24 to 36 hours to remove unreacted monomers to obtain a pure amphoteric polymer ADL.

[0036] Reaction temperature 60-75°C, reaction time 6-9h;

[0037] The molar ratio of acrylic acid, dimethyldiallylammonium chloride and lauryl methacrylate is 1:2 to 5:0.5; the amount of initiator AIBN is 0.5 to 1.0% of the total weight of the monomers;

[0038] Step 2: Synthesis of an integrated amphoteric wet finishing material; specifically:

[0039] Step 2.1: The amphoteric polymer ADL is dissolved in anhydrous ethanol, and then N-hydroxysuccinimide (NHS) and 1-ethyl-(3-dimethylaminopropyl)-carbodiimide (EDC) are added to activate the reaction system. After stirring for 30 to 60 minutes, rhodamine B-ethylenediamine (RhB-EDA) is added, and the reaction temperature is raised to 60 to 75°C. The reaction is refluxed for 12 to 36 hours. After the reaction is completed, the mixed solution is transferred to a dialysis bag and dialyzed against anhydrous ethanol for 24 to 36 hours. The solvent is then removed by distillation under reduced pressure to obtain ADL-RhB, a light pink powder, i.e., a reddish amphoteric polymer.

[0040] The molar ratio of the amphoteric polymer ADL, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)-carbodiimide and rhodamine B-ethylenediamine is 10-15:1.5-2.0:3.0-4.0:1.0-1.5;

[0041] Step 2.2: Dissolve the amphoteric polymer ADL in anhydrous ethanol, then add NHS and EDC to activate the reaction system. After stirring for 30 to 60 minutes, dissolve aminofluorescein (FITC) in hot anhydrous ethanol and add it to the ethanol solution of the amphoteric polymer ADL. Raise the temperature of the reaction system to 60 to 75°C and reflux for 12 to 36 hours. After the reaction is complete, transfer the mixed solution to a dialysis bag and dialyze it in anhydrous ethanol for 24 to 36 hours. Remove the solvent by distillation under reduced pressure to obtain a light yellow powder, which is ADL-FITC, a green amphoteric polymer.

[0042] The molar ratio of the amphoteric polymer ADL, NHS, EDC, and aminofluorescein is 10-15:1.5-2.0:3.0-4.0:1.0-1.5;

[0043] Step 2.3: The amphoteric polymer ADL is added to anhydrous ethanol, followed by the addition of NHS and EDC, and the reaction is activated for 30 to 60 minutes. Aminopyrene (Py) is dissolved in hot anhydrous ethanol and slowly added dropwise to the ethanol solution of the amphoteric polymer ADL. The reaction system is heated to 60 to 75°C and refluxed for 12 to 36 hours. After the reaction is complete, the mixed solution is dialyzed against anhydrous ethanol for 24 to 36 hours, and the solvent is removed by distillation under reduced pressure to obtain a dark brown powder ADL-Py, i.e., a bluish amphoteric polymer.

[0044] The molar ratio of the amphoteric polymer ADL, NHS, EDC, and aminopyrene is 10-15:1.5-2.0:3.0-4.0:1.0-1.5;

[0045] Step 2.4: ADL-RhB, ADL-FITC, and ADL-Py with red, green, and blue colors, respectively, are dissolved in pure water, and the three solutions are mixed together to obtain a mixed solution. The pH of the mixed solution is then adjusted to 3.0-8.0. When the pH is 3.0, the mixed solution is light pink; when the pH is 4.0, the mixed solution is pink-purple; when the pH is 5.0, the mixed solution is light green; when the pH is 6.0, the mixed solution is green; when the pH is 7.0, the mixed solution is yellow-green; and when the pH is 8.0, the mixed solution is yellow, thereby obtaining an integrated amphoteric wet finishing material with different colors.

[0046] The mass ratio of ADL-RhB, ADL-FITC, and ADL-Py was 5–1:1–2:1–2;

[0047] The concentrations of ADL-RhB solution, ADL-FITC solution, and ADL-Py solution were all 0.10–0.15 g / mL;

[0048] When adjusting the pH, use 0.1 mol / L HCl solution or NaOH solution.

[0049] The integrated amphoteric wet-finishing material prepared by the present invention can improve the softness, thickening rate, and physical and mechanical properties of leather, and has significant retanning and fatliquoring effects. The color of the integrated amphoteric wet-finishing material changes with pH changes under visible and ultraviolet light, allowing leather to be dyed to different colors by adjusting the pH of the integrated amphoteric wet-finishing material. Furthermore, the pH-responsive color change and fluorescence properties of the integrated amphoteric wet-finishing material can be used to create specific anti-counterfeiting patterns.

[0050] Example 1

[0051] The preparation method of the pH-responsive color-changing integrated amphoteric wet finishing material of the present invention is as follows: Figure 1 As shown, please follow the steps below:

[0052] Step 1: Synthesis of amphoteric polymer ADL

[0053] 3.6g of acrylic acid, 16.2g of dimethyldiallylammonium chloride, and 6.3g of lauryl methacrylate monomer were dissolved in anhydrous ethanol solution. The mixture was then transferred to a three-necked flask and stirred at 300 rpm. After the solution was uniformly stirred, 0.26g of AIBN ethanol solution was added dropwise. The temperature was raised to 70°C and the reaction was maintained for 6 hours to obtain a bright yellow copolymer with a certain viscosity. After cooling to room temperature, the copolymer was dialyzed against anhydrous ethanol for 36 hours. The solvent was then removed by distillation under reduced pressure to obtain the amphoteric polymer ADL.

[0054] Step 2: Synthesis of integrated amphoteric wet finish material

[0055] Step 2.1: Dissolve 15g of ADL in 80mL of anhydrous ethanol, then add 1.09g of NHS and 3.64g of EDC to activate the reaction system. After 30 minutes, add 4.3g of RhB-EDA. The reaction temperature was raised to 65°C and refluxed for 24 hours. After the reaction, the mixed solution was transferred to a dialysis bag and dialyzed against anhydrous ethanol for 36 hours. The solvent was removed by distillation under reduced pressure to obtain ADL-RhB, a light pink powder.

[0056] Step 2.2: Dissolve 15g of ADL in 80mL of anhydrous ethanol. Then, add 1.09g of NHS and 3.64g of EDC to activate the reaction system. After 30 minutes, dissolve 3.1g of FITC in 20mL of hot anhydrous ethanol. Add the dissolved FITC to the ADL solution, raise the temperature of the reaction system to 65°C, and reflux for 24 hours. After the reaction is complete, transfer the mixed solution to a dialysis bag and dialyze against anhydrous ethanol for 36 hours. Remove the solvent by distillation under reduced pressure to obtain ADL-FITC as a pale yellow powder.

[0057] Step 2.3: Add 15 g of ADL to 80 mL of anhydrous ethanol, followed by 1.09 g of NHS and 3.64 g of EDC. Activate the mixture for 30 min. Dissolve 1.9 g of Py in 10 mL of hot anhydrous ethanol and slowly add it dropwise to the ADL solution. Heat the reaction system to 65°C and reflux for 24 h. After completion of the reaction, dialyze the mixture against anhydrous ethanol for 36 h. Finally, remove the anhydrous ethanol to obtain ADL-Py as a dark brown powder.

[0058] Step 2.4: Weigh 5.0 g of ADL-RhB (6 groups) and dissolve them in 45 mL of purified water, 1.0 g of ADL-FITC (1 group) in 9 mL of purified water, and 1.0 g of ADL-Py (1 group) in 9 mL of purified water. Mix the three solutions in each group to obtain mixed solutions. Adjust the pH of each of the six mixed solutions to a range of 3.0 to 8.0 using 0.1 mol / L HCl or 0.1 mol / L NaOH solution. At pH 3.0, the mixed solution is light pink; at pH 4.0, the mixed solution is pink-purple; at pH 5.0, the mixed solution is light green; at pH 6.0, the mixed solution is green; at pH 7.0, the mixed solution is yellow-green; and at pH 8.0, the mixed solution is yellow. Six groups of integrated amphoteric wet finishing materials with different colors are obtained. The wet finishing materials with different pH values ​​are used in the wet finishing process of leather.

[0059] Figure 2 This is the particle size distribution diagram of the amphoteric polymer and integrated amphoteric wet finishing material prepared in Example 1. As can be seen from the figure, the particle size is concentrated between 100-1000 nm, the average particle size is about 300 nm, and the PDI is less than 0.5, indicating that the polymer can penetrate between the fibrils and fibers, playing a role in lubricating and filling the collagen matrix.

[0060] Figure 3 This is the molecular weight distribution of the amphoteric polymer and integrated amphoteric wet finishing material prepared in Example 1. The figure shows that the molecular weight distribution ranges from 2000 to 4000, meeting the molecular weight requirement for penetration into leather. Furthermore, low-molecular-weight polymers can penetrate collagen fibers, dispersing them, while high-molecular-weight polymers can fill the spaces between fiber bundles, enhancing the fullness of the leather.

[0061] Figure 4 The softness of the leather sample prepared with the integrated amphoteric wet finishing material of Example 1. As can be seen from the figure, the softness of the leather is improved after being treated with the integrated wet finishing material, indicating that the long alkyl chains in the material have an obvious lubricating effect on the collagen fibers.

[0062] Figure 5This is the thickening rate of the leather sample prepared with the integrated amphoteric wet finishing material of Example 1. As can be seen from the figure, the integrated amphoteric wet finishing material has obvious filling performance for leather, which also shows that the material has excellent retanning and fatliquoring performance.

[0063] Figure 6 The dyeing effect of the integrated wet finishing materials with different pH values ​​on leather shows that under visible light, the leather color has an obvious trend of changing from pink to light yellow to orange and then to yellow. Under ultraviolet light, it shows a trend of changing from pink-purple to pink to green and yellow-green, indicating that the material can give the leather rich and colorful colors and has practical application value.

[0064] Figure 7 This is a test of the color uniformity of the leather surface after dyeing with integrated wet finishing materials of different pH values. The data shows that the material has excellent level dyeing properties. Figure 8 This test tests the wet and dry abrasion resistance of leather surface color after dyeing with integrated wet finishing materials of different pH values. This material exhibits excellent wet and dry abrasion resistance due to its bonding to collagen fibers through hydrogen bonds and electrostatic adsorption. Figure 9 The anti-counterfeiting pattern prepared for leather dyed with different pH integrated wet finishing materials can safeguard the authenticity of genuine leather products by changing color in response to pH and presenting different colors under ultraviolet light.

[0065] Example 2

[0066] The preparation method of the pH-responsive color-changing integrated amphoteric wet finishing material of the present invention is specifically implemented according to the following steps:

[0067] Step 1: Synthesis of amphoteric polymer ADL

[0068] 3.6g of acrylic acid, 24.2g of dimethyldiallylammonium chloride, and 6.3g of lauryl methacrylate monomer were dissolved in anhydrous ethanol solution. The mixture was then transferred to a three-necked flask and stirred at 300 rpm. After the solution was uniformly stirred, 0.34g of AIBN ethanol solution was added dropwise. The temperature was raised to 70°C and the reaction was maintained for 6 hours to obtain a bright yellow copolymer with a certain viscosity. After cooling to room temperature, the copolymer was dialyzed against anhydrous ethanol for 36 hours. The solvent was then removed by distillation under reduced pressure to obtain the amphoteric polymer ADL.

[0069] Step 2: Synthesis of integrated amphoteric wet finish material

[0070] Step 2.1: Dissolve 20 g of ADL in 100 mL of anhydrous ethanol. Then, add 1.4 g of NHS and 4.7 g of EDC to activate the reaction system. After 30 minutes, add 5.7 g of RhB-EDA. The reaction temperature is raised to 65°C and refluxed for 24 hours. After the reaction is complete, transfer the mixed solution to a dialysis bag and dialyze against anhydrous ethanol for 36 hours. Remove the solvent by distillation under reduced pressure to obtain ADL-RhB, a light pink powder.

[0071] Step 2.2: Dissolve 20g of ADL in 100mL of anhydrous ethanol. Then, add 1.4g of NHS and 4.7g of EDC to activate the reaction system. After 30 minutes, dissolve 4.03g of FITC in 20mL of hot anhydrous ethanol. Add the dissolved FITC to the ADL solution, raise the temperature of the reaction system to 65°C, and reflux for 24 hours. After the reaction is complete, transfer the mixed solution to a dialysis bag and dialyze against anhydrous ethanol for 36 hours. Remove the solvent by distillation under reduced pressure to obtain ADL-FITC as a pale yellow powder.

[0072] Step 2.3: Add 20 g of ADL to 100 mL of anhydrous ethanol, followed by 1.4 g of NHS and 4.7 g of EDC. Activate the mixture for 30 min. Dissolve 2.47 g of Py in 10 mL of hot anhydrous ethanol and slowly add it dropwise to the ADL solution. Heat the reaction system to 65°C and reflux for 24 h. After the reaction is complete, dialyze the mixture against anhydrous ethanol for 36 h. Finally, remove the anhydrous ethanol to obtain ADL-Py as a dark brown powder.

[0073] Step 2.4: Weigh six groups of 4.0 g ADL-RhB and dissolve them in 46 mL of pure water, 2.0 g ADL-FITC and 1.0 g ADL-Py in 9 mL of pure water, respectively. Mix the three solutions in each group to obtain mixed solutions. Use 0.1 mol / L HCl or 0.1 mol / L NaOH solution to adjust the pH of the six mixed solutions to 3.0-8.0. When the pH is 3.0, the mixed solution is light pink; when the pH is 4.0, the mixed solution is pink-purple; when the pH is 5.0, the mixed solution is light green; when the pH is 6.0, the mixed solution is green; when the pH is 7.0, the mixed solution is yellow-green; and when the pH is 8.0, the mixed solution is yellow. Six groups of integrated amphoteric wet finishing materials with different colors are obtained. The wet finishing materials with different pH values ​​are applied to the wet finishing process of leather.

[0074] Example 3

[0075] The preparation method of the pH-responsive color-changing integrated amphoteric wet finishing material of the present invention is specifically implemented according to the following steps:

[0076] Step 1: Synthesis of amphoteric polymer ADL

[0077] 3.6g of acrylic acid, 32.3g of dimethyldiallylammonium chloride, and 6.3g of lauryl methacrylate monomer were dissolved in anhydrous ethanol solution. The mixture was then transferred to a three-necked flask and stirred at 300 rpm. After the solution was uniformly stirred, 0.42g of AIBN ethanol solution was added dropwise. The temperature was raised to 70°C and the reaction was maintained for 6 hours to obtain a bright yellow copolymer with a certain viscosity. After cooling to room temperature, the copolymer was dialyzed against anhydrous ethanol for 36 hours. The solvent was then removed by distillation under reduced pressure to obtain the amphoteric polymer ADL.

[0078] Step 2: Synthesis of the “all-in-one” amphoteric wet finish material

[0079] Step 2.1: Dissolve 30 g of ADL in 160 mL of anhydrous ethanol. Then, add 2.18 g of NHS and 7.28 g of EDC to activate the reaction system. After 30 minutes, add 8.6 g of RhB-EDA. The reaction temperature is raised to 65°C and refluxed for 24 hours. After the reaction is complete, transfer the mixed solution to a dialysis bag and dialyze against anhydrous ethanol for 36 hours. Remove the solvent by distillation under reduced pressure to obtain ADL-RhB, a light pink powder.

[0080] Step 2.2: Dissolve 30g of ADL in 160mL of anhydrous ethanol. Then, add 2.18g of NHS and 7.28g of EDC to activate the reaction system. After 30 minutes, dissolve 6.2g of FITC in 40mL of hot anhydrous ethanol. Add the dissolved FITC to the ADL solution, raise the temperature of the reaction system to 65°C, and reflux for 24 hours. After the reaction is complete, transfer the mixed solution to a dialysis bag and dialyze against anhydrous ethanol for 36 hours. Remove the solvent by distillation under reduced pressure to obtain ADL-FITC as a pale yellow powder.

[0081] Step 2.3: Add 30 g of ADL to 160 mL of anhydrous ethanol, followed by 2.18 g of NHS and 7.28 g of EDC. Activate the mixture for 30 min. Dissolve 3.8 g of Py in 20 mL of hot anhydrous ethanol and slowly add it dropwise to the ADL solution. Heat the reaction system to 65°C and reflux for 24 h. After the reaction is complete, dialyze the mixture against anhydrous ethanol for 36 h. Finally, remove the anhydrous ethanol to obtain ADL-Py as a dark brown powder.

[0082] Step 2.4: Weigh six groups of 4.0 g ADL-RhB, dissolve them in 46 mL of pure water, 1.0 g ADL-FITC, and 2.0 g ADL-Py, dissolve them in 9 mL of pure water, mix the three solutions in each group together to obtain mixed solutions, and adjust the pH of the six mixed solutions to 3.0-8.0 with 0.1 mol / L HCl or 0.1 mol / L NaOH solution. When the pH is 3.0, the mixed solution is light pink; when the pH is 4.0, the mixed solution is pink-purple; when the pH is 5.0, the mixed solution is light green; when the pH is 6.0, the mixed solution is green; when the pH is 7.0, the mixed solution is yellow-green; and when the pH is 8.0, the mixed solution is yellow. Six groups of integrated amphoteric wet finishing materials with different colors are obtained. The wet finishing materials with different pH values ​​are applied to the wet finishing process of leather.

Claims

1. A method for preparing an integrated amphoteric wet finishing material that can change color in response to pH, characterized in that: Please follow the steps below to implement it: Step 1: Using acrylic acid, dimethyldiallylammonium chloride, and lauryl methacrylate as monomers, an amphoteric polymer ADL is synthesized by free radical polymerization; specifically: Acrylic acid, dimethyldiallylammonium chloride, and lauryl methacrylate were mixed with anhydrous ethanol to dissolve them, and an initiator azobisisobutyronitrile ethanol solution was added dropwise to carry out a polymerization reaction at a temperature of 60-75°C for 6-9 hours. After the reaction was completed, the reaction solution was dialyzed in anhydrous ethanol using a dialysis bag with a molecular weight of 500 for 24-36 hours to remove unreacted monomers to obtain a pure amphoteric polymer ADL. The molar ratio of acrylic acid, dimethyldiallylammonium chloride and lauryl methacrylate is 1:2~5:0.5; the amount of initiator azobisisobutyronitrile is 0.5~1.0% of the total weight of acrylic acid, dimethyldiallylammonium chloride and lauryl methacrylate; Step 2: Rhodamine B-ethylenediamine, aminofluorescein, and aminopyrene are grafted onto the amphoteric polymer ADL respectively, and the three polymers are mixed to prepare an integrated amphoteric wet finishing material; specifically: Step 2.1: Dissolve the amphoteric polymer ADL in anhydrous ethanol, then add N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)-carbodiimide to activate the reaction system. After stirring for 30-60 minutes, add rhodamine B-ethylenediamine and reflux. After the reaction is complete, transfer the mixed solution to a dialysis bag and dialyze against anhydrous ethanol. Remove the solvent by vacuum distillation to obtain a light pink powder, ADL-RhB. The molar ratio of the amphoteric polymer ADL, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)-carbodiimide and rhodamine B-ethylenediamine is 10-15:1.5-2.0:3.0-4.0:1.0-1.5; Step 2.2: Dissolve the amphoteric polymer ADL in anhydrous ethanol, then add N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)-carbodiimide to activate the reaction system. After stirring for 30-60 minutes, dissolve aminofluorescein in hot anhydrous ethanol and add it to the ethanol solution of the amphoteric polymer ADL. Reflux the solution. After the reaction is complete, transfer the mixed solution to a dialysis bag and dialyze against anhydrous ethanol. Remove the solvent by distillation under reduced pressure to obtain a pale yellow powder, ADL-FITC. The molar ratio of the amphoteric polymer ADL, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)-carbodiimide, and aminofluorescein is 10-15:1.5-2.0:3.0-4.0:1.0-1.5; Step 2.3: Add the amphoteric polymer ADL to anhydrous ethanol, followed by the addition of N-hydroxysuccinimide and 1-ethyl-(3-dimethylaminopropyl)-carbodiimide. Activate the reaction for 30–60 minutes. Dissolve aminopyrene in hot anhydrous ethanol and slowly add it dropwise to the ethanol solution of the amphoteric polymer ADL. Reflux the reaction. After completion of the reaction, dialyze the mixture against anhydrous ethanol and remove the solvent by vacuum distillation to obtain a dark brown powder, ADL-Py. The molar ratio of the amphoteric polymer ADL, N-hydroxysuccinimide, 1-ethyl-(3-dimethylaminopropyl)-carbodiimide, and aminopyrene is 10-15:1.5-2.0:3.0-4.0:1.0-1.5; Step 2.4: Dissolve ADL-RhB, ADL-FITC, and ADL-Py in purified water, respectively, mix the three solutions to obtain a mixed solution, and then adjust the pH of the mixed solution to 3-8 to obtain an integrated amphoteric wet finishing material; The mass ratio of ADL-RhB, ADL-FITC and ADL-Py is 5~1:1~2:1~2; the concentrations of ADL-RhB solution, ADL-FITC solution and ADL-Py solution are all 0.10~0.15 g / mL.

2. The method for preparing the integrated amphoteric wet finishing material capable of changing color in response to pH according to claim 1, characterized in that: In the steps 2.1, 2.2 and 2.3, the reflux reaction temperature is 60-75° C., the reflux reaction time is 12-36 h, and the dialysis time is 24-36 h.

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