An organic-inorganic hybrid formaldehyde-free fixing agent, a preparation method and application thereof

Abstract

The application discloses an organic-inorganic hybrid formaldehyde-free fixing agent and a preparation method and application thereof, and belongs to the technical field of textile auxiliaries. The fixing agent is prepared by using dimethyl diallyl ammonium chloride and methacryloyloxyethyl trimethyl ammonium chloride as reaction monomers, N-vinyl pyrrolidone as an organic modifier, and trisodium phosphate and bismuth nitrate as inorganic modifiers, and the organic-inorganic hybrid crosslinking structure is formed through a polymerization reaction. The preparation method comprises the following steps: pre-complexing bismuth nitrate and citric acid, pre-activating a silane coupling agent, mixing the components, and then performing stage pH regulation, ultrasonic-assisted dispersion, high-temperature curing and other steps. The fixing agent is prepared by means of coordination crosslinking of an organic polymer chain and bismuth ions and covalent connection of a silane coupling agent, so that a double network structure is formed, the wet rubbing fastness and the soaping fastness are significantly improved, the fabric is endowed with antibacterial and ultraviolet resistance functions, the hydrophilicity and the hand feeling are improved, and the fixing agent does not contain formaldehyde, and can be widely applied to post-treatment of textile dyeing.

Description

Technical Field

[0001] This invention belongs to the field of textile auxiliaries technology, specifically relating to an organic-inorganic hybrid formaldehyde-free color-fixing agent, its preparation method, and its application. Background Technology

[0002] Fixing agents are indispensable auxiliaries in textile dyeing and finishing processes. Their main function is to enhance the adhesion of dyes to fibers and improve the color fastness of dyed fabrics to various conditions such as washing, rubbing, and perspiration. For a long time, the dyeing and printing industry has widely used resin-based fixing agents, represented by dicyandiamide and formaldehyde condensates. While these fixing agents offer significant color-fixing effects, they release free formaldehyde during application, posing a potential threat to the production environment and human health. With increasingly stringent domestic and international ecological standards for textiles and growing consumer awareness of environmental protection, the development of formaldehyde-free fixing agents has become an important research direction in the dyeing and finishing field.

[0003] Existing formaldehyde-free fixing agents can be mainly divided into several categories, including reactive, resin-based, and polymer-based. Reactive fixing agents typically use epichlorohydrin and amine compounds as raw materials, improving color fastness by forming a cross-linked network on the fiber. However, these products often have drawbacks such as noticeable color changes and a stiff feel. Resin-based formaldehyde-free fixing agents mostly use condensates of polyamines and dicyandiamide, which have strong dye fixation capabilities, but their wet rubbing resistance still needs improvement. Polymer-based fixing agents, especially quaternary ammonium salt cationic polymers with dimethyl diallyl ammonium chloride (DMDAAC) as the monomer, contain a large number of quaternary ammonium cationic groups in their molecular chains. These groups can form ionic bonds with anionic dyes through electrostatic interactions and simultaneously form a polymer film on the fiber surface, thus achieving good color fastening effects. Combined with their formaldehyde-free and environmentally friendly characteristics, they have received widespread attention in recent years.

[0004] However, despite the good performance of polydimethyldiallyl ammonium chloride-based fixing agents in terms of washing fastness, they still have significant shortcomings in practical applications. Studies have shown that the ionic bonds between these fixing agents and dyes, as well as the van der Waals forces between them and fibers, are easily disrupted under external forces, making it difficult to achieve ideal levels of rubbing fastness, especially wet rubbing fastness. Even with numerous attempts at structural modification, the problem of low wet rubbing fastness has not been fundamentally solved, becoming a major bottleneck restricting their application. In addition, existing polymer fixing agents have relatively limited functions, mainly relying on electrostatic adsorption to achieve color fixation, making it difficult to impart additional functions such as antibacterial and UV protection to fabrics. Furthermore, they are prone to color changes or a stiffer hand feel when treating dark-colored fabrics or sensitive colors.

[0005] Therefore, how to further improve the overall performance of color-fixing agents while maintaining their formaldehyde-free and environmentally friendly characteristics, especially to solve the common defect of insufficient wet rubbing fastness, and at the same time to endow the products with multifunctionality, has become a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0006] The purpose of this invention is to provide an organic-inorganic hybrid formaldehyde-free color-fixing agent, its preparation method, and its application. This color-fixing agent significantly improves the wet rubbing fastness and soaping fastness by constructing a coordination crosslinking structure between organic polymer chains and bismuth ions. At the same time, it endows fabrics with multifunctional properties such as antibacterial and UV resistance, and improves hydrophilicity and hand feel, thereby overcoming the defects of existing formaldehyde-free color-fixing agents that have single functions and insufficient wet rubbing fastness.

[0007] To achieve the above objectives, the present invention provides the following technical solution: The first aspect of this invention provides a method for preparing an organic-inorganic hybrid formaldehyde-free fixing agent, comprising the following steps: (1) Dissolve bismuth nitrate (Bi(NO3)3) in deionized water, add citric acid, stir, and obtain a bismuth-citric acid complex solution; (2) Dimethyl diallyl ammonium chloride (DMDAAC), methacryloyloxyethyl trimethyl ammonium chloride (DMC), N-vinylpyrrolidone (NVP), trisodium phosphate, silane coupling agent and bismuth-citric acid complex from step (1) are added to a reaction vessel, the pH is adjusted to 2.5-3.0, some initiator is added, and polymerization reaction is carried out. (3) Adjust the pH of the reaction system obtained in step (2) to 4.5-5.0, turn on the ultrasonic processor, and add the remaining initiator dropwise into the reaction system; (4) After the addition is complete, raise the temperature and maintain the temperature for the reaction; (5) After the reaction is complete, the mixture is cooled to obtain the organic-inorganic hybrid formaldehyde-free fixing agent.

[0008] Further, the mass ratio of bismuth nitrate to citric acid in step (1) is 1:(0.3-0.6).

[0009] Bismuth nitrate readily hydrolyzes in water to form insoluble precipitates. If directly added to the polymerization system, bismuth ions will precipitate out in large quantities in the early stages of the reaction, failing to disperse evenly in the polymer matrix and hindering their subsequent coordination and crosslinking. Citric acid, as a multidentate ligand, forms a stable chelate structure with bismuth ions through its carboxyl group, retaining the bismuth ions in a dissolved state in the solution, allowing them to successfully pass through the acidic stage of the polymerization reaction. As the pH of the reaction system increases, the complexation equilibrium shifts, and bismuth ions gradually dissociate and are released from the citric acid ligand, coordinating with nitrogen atoms and phosphate groups on the polymer chains to form a crosslinked network. The citric acid complex effectively controls the timing of bismuth ion release, matching it with polymer chain formation and phosphate introduction in time, ultimately achieving uniform distribution and effective crosslinking of bismuth ions in the organic polymer matrix.

[0010] Further, the silane coupling agent in step (2) is γ-glycidoxypropyltrimethoxysilane (KH560).

[0011] Furthermore, the silane coupling agent is pre-activated before use. The pre-activation method includes: dissolving the silane coupling agent in deionized water, adjusting the pH to 4.0-5.0 with glacial acetic acid, and hydrolyzing and activating it at 30-40°C for 30-60 minutes to obtain an activated silane coupling agent solution.

[0012] Unactivated silane coupling agents, particularly methoxy groups, hydrolyze slowly and are unable to function effectively in the polymerization system. Pre-activation treatment hydrolyzes the methoxy groups into highly reactive silanol groups, enabling them to form Si-O-Bi covalent bonds with bismuth ions in the early stages of polymerization, anchoring the inorganic bismuth component to the silane molecule. Simultaneously, the retained epoxy groups react with amine or hydroxyl groups on the polymer chain, integrating into the organic network. This process connects organic polymerization and inorganic coordination via covalent bonds, forming a dual network structure that significantly enhances the stability and integrity of the crosslinked network. Bismuth ions are more evenly distributed and less prone to migration and loss. Furthermore, the silane itself helps improve the film-forming quality of the fixing agent.

[0013] Further, in step (2), based on 100 parts by mass of dimethyl diallyl ammonium chloride, the amounts of each component are as follows: 15-25 parts by mass of methacryloyloxyethyltrimethylammonium chloride, 8-12 parts by mass of N-vinylpyrrolidone, 15-25 parts by mass of trisodium phosphate, 2-5 parts by mass of silane coupling agent, and 3-8 parts by mass of bismuth-citric acid complex (calculated as bismuth nitrate).

[0014] Further, the initiator is ammonium persulfate, and its total addition amount is 0.8-1.5% of the total mass of dimethyl diallyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride and N-vinylpyrrolidone; the initiator added in step (2) is 20-40% of the total initiator.

[0015] Furthermore, the polymerization reaction in step (2) is carried out at a temperature of 65-70°C for 1.5-2.5 hours.

[0016] Furthermore, the remaining initiator in step (3) is added over a period of 1.5-2.5 hours.

[0017] Furthermore, the temperature of the heat preservation reaction in step (4) is 80-85℃, and the heat preservation reaction time is 1.5-2.5 hours.

[0018] The fixing agent of this invention constructs a dual crosslinking network through an organic-inorganic hybrid, fundamentally changing the traditional fixing agent's reliance solely on electrostatic adsorption. Dimethyl diallyl ammonium chloride and methacryloyloxyethyl trimethyl ammonium chloride copolymerize to form a cationic polymer backbone, providing fundamental positive charge sites for binding with anionic dyes. The introduction of DMC increases the cationic density and molecular weight of the molecular chain. N-vinylpyrrolidone, as a comonomer, is embedded in the polymer chain; its lactam structure binds to water molecules through hydrogen bonds, forming a hydration layer on the fiber surface. This prevents excessive interaction between the cationic segments and the dye, thus preventing color change, and also improves the film's flexibility and hydrophilicity.

[0019] Bismuth ions are pre-complexed with citric acid to achieve controlled release, allowing them to participate uniformly in network formation during the later stages of polymerization. The phosphate groups introduced by trisodium phosphate form bismuth phosphate structural units with the released bismuth ions. These nanoscale inorganic clusters are anchored to the polymer chain through coordination, while the phosphate groups themselves can also undergo ion exchange with the quaternary ammonium salt, forming a polymer-phosphate-bismuth bridging structure. After pre-activation, the silane coupling agent forms Si-O-Bi covalent bonds with bismuth ions, and the epoxy groups are integrated into the organic polymer network, achieving chemical bonding between the organic and inorganic phases.

[0020] The entire system ultimately forms a dual network structure with the organic polymer as the continuous phase and bismuth-phosphate clusters as the dispersed phase. Compared with traditional fixing agents, the advantage of this structure lies in the multiple anchoring of dyes: in addition to electrostatic adsorption, the inorganic clusters physically embed and coordinate dye molecules, significantly improving the dye's resistance to migration in the wet state, which is key to improving wet rubbing fastness. At the same time, bismuth ions themselves endow antibacterial and anti-UV functions, and the residual groups of citric acid and silane further increase the hydrophilicity and film integrity of the network.

[0021] The second aspect of this invention provides an organic-inorganic hybrid formaldehyde-free fixing agent, which is obtained by the above-mentioned preparation method of an organic-inorganic hybrid formaldehyde-free fixing agent.

[0022] The third aspect of this invention provides the application of the above-mentioned organic-inorganic hybrid formaldehyde-free fixing agent in the post-dyeing treatment of textiles.

[0023] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows: (1) By pre-complexing bismuth nitrate with citric acid, the present invention solves the problem of easy hydrolysis and precipitation of bismuth ions during polymerization, realizes the controllable release and uniform dispersion of bismuth ions, and enables them to effectively coordinate with polymer chains and phosphate groups in the later stage of the reaction to form a stable organic-inorganic hybrid cross-linking network, which significantly improves the anchoring ability of the fixing agent to the dye.

[0024] (2) The present invention uses a pre-activated silane coupling agent to construct a covalent-coordinated dual connection between organic polymer and inorganic bismuth ions. The silanol group forms a Si-O-Bi bond with the bismuth ion, and the epoxy group is incorporated into the organic polymer network, making the hybrid structure more complete and stable. The wet rubbing fastness can reach grade 3-3.5, which is significantly improved compared with traditional color fixing agents.

[0025] (3) In this invention, N-vinylpyrrolidone is introduced as a comonomer. Its lactam structure combines with water molecules through hydrogen bonds to form a hydration layer on the fiber surface, which effectively prevents color change caused by excessive interaction between cationic segments and dyes. At the same time, it improves the flexibility and hydrophilicity of the film, making the hydrophilicity of the treated fabric better than that of commercially available products, and the water droplet diffusion time is within 1.5 seconds.

[0026] (4) In this invention, phosphate ions are introduced by trisodium phosphate as a bridging ligand to connect bismuth ions with quaternary ammonium salts on polymer chains, forming a multi-point cross-linked structure of "polymer-phosphate-bismuth", which further enhances the cross-linking density and structural integrity of the network, so that the washing fastness reaches grade 3.5-4 and the dry rubbing fastness reaches grade 4.

[0027] (5) The color-fixing agent prepared by the present invention is formaldehyde-free, environmentally friendly and safe, and the introduction of bismuth ions endows the fabric with antibacterial and anti-ultraviolet functions, overcoming the defect of the single function of traditional color-fixing agents and realizing the synergistic effect of color fixing and functional finishing. Attached Figure Description

[0028] Figure 1 Infrared test image of the formaldehyde-free fixing agent prepared in Example 1.

[0029] Figure 2 The results of dry friction fastness tests are shown in the examples and comparative examples.

[0030] Figure 3 The results of wet friction fastness tests are shown in the examples and comparative examples.

[0031] Figure 4 The results of the wash fastness tests are shown in the examples and comparative examples. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below. 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.

[0033] Example 1 This embodiment provides an organic-inorganic hybrid formaldehyde-free fixing agent, the preparation method of which includes the following steps: (1) Dissolve 5.0 g of bismuth nitrate in 20 mL of deionized water, add 2.5 g of citric acid, and stir at 40 °C for 30 minutes to obtain a bismuth-citric acid complex solution; (2) Pre-activate silane coupling agent KH560: Dissolve 3.0 g KH560 in 15 mL of deionized water, adjust the pH to 4.5 with glacial acetic acid, and hydrolyze and activate at 35°C for 45 minutes to obtain an activated silane coupling agent solution; add 100.0 g dimethyl diallyl ammonium chloride (DMDAAC), 20.0 g methacryloyloxyethyl trimethyl ammonium chloride (DMC), 10.0 g N-vinylpyrrolidone (NVP), 20.0 g trisodium phosphate, the aforementioned activated silane coupling agent solution and the bismuth-citric acid complex solution obtained in step (1) to the reaction vessel, add deionized water to a total mass of 500 g, stir evenly, adjust the pH to 2.8 with glacial acetic acid, raise the temperature to 68°C, add 0.47 g ammonium persulfate (dissolved in 5 mL of water), and polymerize at 68°C for 2 hours; (3) Adjust the pH of the reaction system obtained in step (2) to 4.8 with 5% sodium hydroxide solution, turn on the ultrasonic processor (power 250 W, frequency 40 kHz), and add 1.09 g of ammonium persulfate (dissolved in 10 mL of water) dropwise into the reaction system at a uniform rate for about 2 hours; (4) After the addition is complete, heat the system to 82°C and keep it at that temperature for 2 hours. (5) After the reaction is complete, cool naturally to 45°C and discharge the material to obtain an organic-inorganic hybrid formaldehyde-free color-fixing agent.

[0034] The infrared spectrum of the formaldehyde-free fixing agent prepared in this embodiment is shown below. Figure 1 As shown, in the infrared spectrum at approximately 890 cm⁻¹ -1 An absorption peak appears at [value missing], which can be attributed to the stretching vibrations of the Si-O-Si or Si-OC bonds introduced by the silane coupling agent, as well as the vibrations of the PO bonds in the phosphate group. This indicates that the silane coupling agent and trisodium phosphate have successfully participated in the reaction and integrated into the organic-inorganic hybrid system. 2322.746 cm⁻¹ -1 and 1953.893 cm -1 These frequencies can be attributed to the stretching vibrations or combination frequencies of the CH bonds in the quaternary ammonium groups of the polymer backbone, consistent with the structural characteristics of DMDAAC, DMC, and NVP copolymers. Furthermore, in the low-frequency region (approximately 500-600 cm⁻¹), -1 The absence of obvious impurity peaks indicates that bismuth ions exist stably in the polymer network in a coordinated form.

[0035] Example 2 This embodiment provides an organic-inorganic hybrid formaldehyde-free fixing agent, the preparation method of which includes the following steps: (1) Dissolve 7.0 g of bismuth nitrate in 25 mL of deionized water, add 3.5 g of citric acid, and stir at 38 °C for 45 minutes to obtain a bismuth-citric acid complex solution; (2) Pre-activate silane coupling agent KH560: Dissolve 4.5 g KH560 in 20 mL of deionized water, adjust the pH to 4.3 with glacial acetic acid, and hydrolyze and activate at 33°C for 55 minutes to obtain an activated silane coupling agent solution; add 100.0 g dimethyl diallyl ammonium chloride, 24.0 g methacryloyloxyethyl trimethyl ammonium chloride, 9.5 g N-vinylpyrrolidone, 17.0 g trisodium phosphate, the aforementioned activated silane coupling agent solution and the bismuth-citric acid complex solution obtained in step (1) to the reaction vessel, add deionized water to a total mass of 500 g, stir evenly, adjust the pH to 2.7 with glacial acetic acid, raise the temperature to 69°C, add 0.39 g ammonium persulfate (dissolved in 4 mL of water), and polymerize at 69°C for 1.6 hours; (3) Adjust the pH of the reaction system obtained in step (2) to 4.9 with 5% sodium hydroxide solution, turn on the ultrasonic processor (power 220 W, frequency 40 kHz), and add 1.13 g of ammonium persulfate (dissolved in 12 mL of water) dropwise to the reaction system at a uniform rate for about 2 hours; (4) After the addition is complete, heat the system to 81°C and keep it at that temperature for 2 hours. (5) After the reaction is complete, cool to 46°C and discharge to obtain a light yellow transparent liquid, which is an organic-inorganic hybrid formaldehyde-free color-fixing agent.

[0036] Comparative Example 1 This comparative example provides a formaldehyde-free fixing agent, the preparation method of which includes the following steps: (1) Pre-activate silane coupling agent KH560: Dissolve 3.0 g KH560 in 15 mL of deionized water, adjust the pH to 4.5 with glacial acetic acid, and hydrolyze and activate at 35℃ for 45 minutes to obtain activated silane coupling agent solution. (2) Add 100.0 g of dimethyl diallyl ammonium chloride, 30.0 g of tert-butylacrylamide and the silane coupling agent solution activated in step (1) to the reaction vessel, add deionized water to make the total mass 500 g, stir evenly, adjust the pH to 2.8 with glacial acetic acid, raise the temperature to 68°C, add 0.47 g of ammonium persulfate (dissolved in 5 mL of water), and polymerize at 68°C for 2 hours; (3) Adjust the pH of the reaction system obtained in step (2) to 4.8 with 5% sodium hydroxide solution, turn on the ultrasonic processor (power 250 W, frequency 40 kHz), and add 1.09 g of ammonium persulfate (dissolved in 10 mL of water) to the reaction system at a uniform rate over 2 hours, while continuing ultrasonic treatment for 45 minutes during the addition. (4) After the addition is complete, heat the system to 82°C and keep it at that temperature for 2 hours. (5) After the reaction is complete, cool to 45°C and discharge to obtain the color-fixing agent product.

[0037] Comparative Example 2 The difference between this comparative example and Example 1 is that step (2) of the pre-activation treatment of the silane coupling agent is omitted; in step (3) the preparation process only dimethyl diallyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, N-vinylpyrrolidone, trisodium phosphate and bismuth-citric acid complex solution are added to the reaction vessel, and the remaining steps and process parameters are the same as in Example 1.

[0038] Comparative Example 3 The difference between this comparative example and Example 1 is that the bismuth-citric acid complex preparation step (1) is omitted, and in step (3), only dimethyl diallyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, N-vinylpyrrolidone, trisodium phosphate and activated silane coupling agent solution are added to the reaction vessel. The remaining steps and process parameters are the same as in Example 1.

[0039] Comparative Example 4 The difference between this comparative example and Example 1 is that N-vinylpyrrolidone was not added in step (3), and only dimethyl diallyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, trisodium phosphate, activated silane coupling agent solution and bismuth-citric acid complex solution were added to the reaction vessel. The remaining steps and process parameters were the same as in Example 1.

[0040] Comparative Example 5 The difference between this comparative example and Example 1 is that the methacryloyloxyethyltrimethylammonium chloride in step (3) is replaced with diallylamine, and the amount is 5 g.

[0041] Performance testing The fixing agents prepared in Examples 1-2 and Comparative Examples 1-5 were diluted with water to prepare working solutions of 30 g / L, and the pH was adjusted to 5-6. The dyed rose-red polyester-cotton fabric was immersed in the working solution at a liquor ratio of 1:20 and treated at 60°C for 30 minutes. After removal, excess working solution was rolled off (roll-off rate 80%), and the fabric was dried at 100°C to obtain the fabric sample to be tested.

[0042] The following performance tests were performed on the fabric samples treated by the above method: 1. Wash fastness: Tested according to GB / T 3921-2008 "Textiles - Tests for color fastness to washing". Use 5g / L soap solution, sample size 100mm×40mm, with multifiber lining fabric attached, treat at 40℃ for 30 minutes, and evaluate the staining grade using a gray scale.

[0043] 2. Dry and wet rubbing fastness: Tested according to GB / T 3920-2008 "Textiles - Tests for color fastness to rubbing". Fix the sample on the rubbing fastness tester and perform dry and wet rubbing with standard rubbing cloth respectively. Use gray scale to evaluate the staining grade of the rubbing cloth.

[0044] The results of the dry friction fastness test are as follows Figure 2 As shown in the figure, ag represents samples from Examples 1-2 and Comparative Examples 1-5, respectively.

[0045] The wet friction fastness test results are as follows Figure 3 As shown in the figure, ag represents samples from Examples 1-2 and Comparative Examples 1-5, respectively.

[0046] 3. Wash fastness: Determined according to method A (1) in GB / T 3921-2008. After the sample is sewn with a multi-fiber lining fabric, it is treated in soap solution at 40℃ for 30 minutes, and the staining grade is evaluated after washing and drying.

[0047] The results of the wash fastness test are as follows: Figure 4 As shown in the figure, ag represents samples from Examples 1-2 and Comparative Examples 1-5, respectively.

[0048] 4. Hydrophilicity: The water droplet diffusion method was used. Water droplets were dropped from a certain height onto the fabric surface, and the time required for the water droplets to completely diffuse was recorded. Each sample was measured 5 times and the average value was taken.

[0049] The test results are shown in Table 1.

[0050] Table 1 Performance Test Results

[0051] The performance test results above show that the color-fixing agents prepared by the method of this invention in Examples 1 and 2 exhibit excellent comprehensive performance on rose-red polyester-cotton fabric. The washing fastness reaches grade 3.5 or higher, the dry rubbing fastness reaches grade 4, and the wet rubbing fastness reaches grade 3.5, significantly better than similar commercially available products. Simultaneously, it exhibits good hydrophilicity, with water droplet diffusion time within 1.5 seconds, indicating that the treated fabric has good hydrophilic properties, which is beneficial for subsequent processing and wearing comfort.

[0052] Comparative Example 1, lacking an inorganic hybrid crosslinking network, relies solely on electrostatic adsorption and hydrophobic association, resulting in weak dye anchoring ability. Wet rubbing fastness drops to grade 2.5, and soaping fastness also significantly decreases, with deteriorating hydrophilicity. Comparative Example 2 lacks the covalent bonds constructed by the silane coupling agent, leading to insufficient organic-inorganic network integrity and a significant decrease in wet rubbing fastness, with other fastness indicators also slightly declining. Comparative Example 3, lacking bismuth ions, cannot form coordination crosslinking centers; trisodium phosphate can only bind to the polymer through electrostatic interactions, resulting in low crosslinking density and a significant decrease in wet rubbing fastness. Comparative Example 4, while retaining the organic-inorganic hybrid structure, lacks the hydrophilic lactam groups of NVP, leading to decreased polymer chain hydrophilicity, significantly deteriorating fabric hydrophilicity, and a tendency for color changes when treating sensitive colors, with a slight decrease in fastness indicators. Comparative Example 5, due to the lack of ester groups and long chains in the diallylamine molecule, has a lower molecular weight and cationic density, resulting in a weakened anchoring effect on the dye, significantly reduced wet rubbing fastness, and poor washing fastness. Its overall performance is inferior to the examples containing DMC.

[0053] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing an organic-inorganic hybrid formaldehyde-free fixing agent, characterized in that, Includes the following steps: (1) Dissolve bismuth nitrate in deionized water, add citric acid, and stir to obtain a bismuth-citric acid complex solution; (2) Dimethyl diallyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride, N-vinylpyrrolidone, trisodium phosphate, silane coupling agent and bismuth-citric acid complex from step (1) are added to a reaction vessel, the pH is adjusted to 2.5-3.0, some initiator is added, and polymerization reaction is carried out. (3) Adjust the pH of the reaction system obtained in step (2) to 4.5-5.0, turn on the ultrasonic processor, and add the remaining initiator dropwise into the reaction system; (4) After the addition is complete, raise the temperature and maintain the temperature for the reaction; (5) After the reaction is complete, the mixture is cooled to obtain the organic-inorganic hybrid formaldehyde-free fixing agent.

2. The preparation method according to claim 1, characterized in that, The mass ratio of bismuth nitrate to citric acid in step (1) is 1:(0.3-0.6).

3. The preparation method according to claim 1, characterized in that, The silane coupling agent in step (2) is γ-glycidoxypropyltrimethoxysilane; the silane coupling agent is pre-activated before use. The pre-activation method includes: dissolving the silane coupling agent in deionized water, adjusting the pH to 4.0-5.0 with glacial acetic acid, and hydrolyzing and activating it at 30-40℃ for 30-60 minutes to obtain an activated silane coupling agent solution.

4. The preparation method according to claim 1, characterized in that, In step (2), based on 100 parts by mass of dimethyl diallyl ammonium chloride, the amounts of each component are as follows: 15-25 parts by mass of methacryloyloxyethyltrimethylammonium chloride, 8-12 parts by mass of N-vinylpyrrolidone, 15-25 parts by mass of trisodium phosphate, 2-5 parts by mass of silane coupling agent, and 3-8 parts by mass of bismuth-citric acid complex (calculated as bismuth nitrate).

5. The preparation method according to claim 1, characterized in that, The initiator is ammonium persulfate, and its total addition amount is 0.8-1.5% of the total mass of dimethyl diallyl ammonium chloride, methacryloyloxyethyl trimethyl ammonium chloride and N-vinylpyrrolidone; the initiator added in step (2) is 20-40% of the total initiator.

6. The preparation method according to claim 1, characterized in that, The polymerization reaction in step (2) is carried out at a temperature of 65-70°C for 1.5-2.5 hours.

7. The preparation method according to claim 1, characterized in that, The remaining initiator in step (3) is added over a period of 1.5-2.5 hours.

8. The preparation method according to claim 1, characterized in that, The temperature of the heat preservation reaction in step (4) is 80-85℃, and the heat preservation reaction time is 1.5-2.5 hours.

9. An organic-inorganic hybrid formaldehyde-free fixing agent, characterized in that, It is obtained by the preparation method of an organic-inorganic hybrid formaldehyde-free fixing agent as described in any one of claims 1-8.

10. The application of the organic-inorganic hybrid formaldehyde-free fixing agent according to claim 9 in the post-dyeing treatment of textiles.

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