Activating and coloring method of polypropylene non-woven fabric

Abstract

The invention relates to an activating and coloring method of a polypropylene non-woven fabric, and belongs to the technical field of fabric coloring. Polypropylene non-woven fabric is modified through polydopamine, then sodium borohydride is used for reduction decoloration, and finally a dye solution is used for coloring. After reduction and decolorization, a benzophenone quaternary ammonium salt compound can be further utilized for modification, so that the color fastness of dyeing is improved. By means of spontaneous polymerization of dopamine on the surface of the polypropylene non-woven fabric, the polypropylene non-woven fabric which is originally hydrophobic and inert is converted into a material with functional activity, the surface performance of the non-woven fabric is improved, the binding capacity of the non-woven fabric and dye is enhanced, and the dyeing uniformity is improved. Sodium borohydride is used for reducing and decolorizing the polydopamine modified polypropylene non-woven fabric, so that brown chromaticity can be effectively removed, follow-up dyeing interference is avoided, active functional groups on the surface of the non-woven fabric are reserved, and good surface performance and structure of the non-woven fabric are maintained.

Description

Technical Field

[0001] This invention relates to an activation coloring method for polypropylene nonwoven fabric, belonging to the field of fabric coloring technology. Background Technology

[0002] Polypropylene fiber nonwoven fabrics are widely used in many applications due to their good air permeability, non-flammability, non-toxicity, and low cost. However, polypropylene fibers are highly hydrophobic and crystallinity, which makes it difficult for dye molecules to penetrate during the dyeing process, resulting in low dye uptake and poor color fastness. Dispersants, surface modification, or special pigments are usually required to achieve coloring of the nonwoven fabric. For example, CN120906001A discloses a blue-gray spunlace nonwoven fabric base paper and its production process. This process utilizes a mesoporous silica-bentonite nanocarrier physical confinement and ion adsorption composite material, combined with cationic starch pre-anchoring, to ensure uniform nanoscale dispersion of the blue-gray tone within the fiber web, significantly reducing decolorization rate and color difference. First, acrylamide is initiated by UV to form a physical network resin, and then in the second stage, polyvinyl alcohol / chitosan is used...

[0003] Sugar cross-linking constructs a chemical color-locking layer, achieving dual physical and chemical color fixation. CN120443486A discloses a dyeing process for nonwoven fabrics, which involves pretreatment with specific surfactants and penetrants, dyeing with reactive dyes and appropriate dyeing auxiliaries, and using cationic color-locking agents to react chemically with the dyes to form stable chemical bonds, ensuring uniform dyeing and vibrant colors in the nonwoven fabrics.

[0004] Modifying the hydrophobic properties of polypropylene fibers to make them hydrophilic plays a crucial role in improving dyeability. Numerous studies have reported on the hydrophilic modification of nonwoven fabrics. For example, CN112626856A discloses a hydrophilic polypropylene nonwoven fabric and its preparation method, CN111621985A discloses a method for preparing a hydrophilic modified polyester nonwoven fabric, and CN112647301A discloses an antibacterial nonwoven fabric and its preparation method. Most of these existing technologies utilize polydopamine to hydrophilically modify the nonwoven fabric, forming a hydrophilic polydopamine layer on the surface of the nonwoven fibers using the self-polymerization function of dopamine, thereby altering the hydrophobic properties of the nonwoven fabric. However, there are few reports in the field of nonwoven fabric dyeing that utilize polydopamine for hydrophilic modification before dyeing.

[0005] While hydrophilic modification with polydopamine can solve the traditional dyeing problems of nonwoven fabrics due to their low number of functional groups and low hydrophilicity, the overall brown color of the modified nonwoven fabric severely interferes with the subsequent dyeing process. Therefore, developing a simple nonwoven fabric dyeing technology that achieves effective dyeing without damaging the fiber structure, improves dyeing uniformity, and avoids color interference is of great application value. Summary of the Invention

[0006] In view of the aforementioned state of the prior art, this invention discovers that hydrophilic modification of polypropylene nonwoven fabric with polydopamine improves its surface properties, thereby enhancing dyeing uniformity and binding ability with dyes during subsequent dyeing processes. Reduction decolorization of the polydopamine-modified polypropylene nonwoven fabric using sodium borohydride not only solves the decolorization problem of polydopamine-modified polypropylene nonwoven fabric but also effectively removes brown hues while retaining the active functional groups on the surface of the polypropylene nonwoven fabric, maintaining its good surface properties and structure, and improving the dyeing effect. Furthermore, this invention further modifies the polypropylene nonwoven fabric with benzophenone quaternary ammonium salt compounds to improve its color fastness.

[0007] Therefore, the object of the present invention is to provide an activation coloring method for polypropylene nonwoven fabric.

[0008] The technical solution for achieving the above-mentioned objectives can be summarized as follows:

[0009] An activation coloring method for polypropylene nonwoven fabric includes the following steps:

[0010] Polypropylene nonwoven fabric is modified with polydopamine, then decolorized using sodium borohydride, and finally colored with a dye solution.

[0011] According to the present invention, preferably, the modification process of polypropylene nonwoven fabric with polydopamine is as follows:

[0012] Polypropylene nonwoven fabric was soaked in Tris-HCl buffer solution of dopamine and reacted at 20-30℃.

[0013] Preferably, the pH of the Tris-HCl buffer is 8.5, and the concentration of dopamine in the Tris-HCl buffer is 1-3 mg / mL;

[0014] Preferably, the reaction time is 10-30 hours. After the reaction is completed, the product is washed with deionized water and dried to obtain polydopamine-modified polypropylene nonwoven fabric.

[0015] According to the present invention, preferably, the concentration of sodium borohydride solution during the reduction and decolorization process is 0.05-0.2 mol / L;

[0016] Preferably, the reduction and decolorization time is 10-30 hours.

[0017] According to the present invention, preferably, the dye is a diazonium salt dye, and more preferably, fixed red RC salt, fast black K salt, or fast deep blue R salt;

[0018] Preferably, the dye solution is an acetone aqueous solution of the dye, and the volume ratio of acetone to water is 1:1.

[0019] Preferably, the concentration of the dye solution is 0.01-0.02 mol / L.

[0020] According to the present invention, preferably, after reduction and decolorization, the product is further modified using a benzophenone quaternary ammonium salt compound, and then colored using a dye solution.

[0021] Preferably, the benzophenone quaternary ammonium salt compound is N,N-dimethyl-N,N-di(dodecyl)methylene benzophenone quaternary ammonium salt.

[0022] According to the present invention, the preferred modification process is as follows:

[0023] The decolorized polypropylene nonwoven fabric was soaked in an ethanol solution of benzophenone quaternary ammonium salt compound and then subjected to photochemical modification reaction by ultraviolet light irradiation.

[0024] Preferably, the concentration of the benzophenone quaternary ammonium salt compound ethanol solution is 0.02-0.03 g / mL.

[0025] The beneficial effects of this invention are as follows:

[0026] 1. This invention utilizes the spontaneous polymerization of dopamine on the surface of polypropylene nonwoven fabric to transform the originally hydrophobic and inert polypropylene nonwoven fabric into a functionalized material, thereby improving the surface properties of the nonwoven fabric, enhancing its binding ability with dyes, and improving dyeing uniformity.

[0027] 2. This invention utilizes sodium borohydride to reduce and decolorize polydopamine-modified polypropylene nonwoven fabric. This not only effectively removes the brown hue and avoids interference with subsequent dyeing, but also retains the active functional groups on the surface of the nonwoven fabric, maintaining its good surface properties and structure.

[0028] 3. This invention further modifies polypropylene nonwoven fabric with benzophenone quaternary ammonium salt compounds to improve the color fastness of the nonwoven fabric. Utilizing the unique molecular structure and chemical properties of benzophenone quaternary ammonium salt compounds, they can undergo efficient and stable coupling reactions with diazonium salt dyes, enabling dye molecules to firmly bind to the surface of the nonwoven fabric in the form of chemical bonds. This overcomes the limitations of traditional dyeing techniques and provides a completely new technical path for nonwoven fabric dyeing. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the mechanism of the coloring based on the coupling reaction between polydopamine structure and diazonium salt in this invention.

[0030] Figure 2 This is a schematic diagram of the mechanism of the coloring reaction based on the coupling reaction between the N,N-dimethyl-N,N-di(dodecyl)methylene benzophenone quaternary ammonium salt structure and the diazonium salt in this invention.

[0031] Figure 3 This is a photograph of the untreated disposable medical mask filter element PP from Example 1.

[0032] Figure 4 This is a photograph of the nonwoven PP-PDA fabric modified and activated by polydopamine in Example 1.

[0033] Figure 5 This is a photograph of the PP-BPDA nonwoven fabric after decolorization in Example 1.

[0034] Figure 6 The images show the nonwoven fabric materials e1 / e2 / e3 after PP-BPDA in Example 1 were colored with red RC salt, lightfast black K salt, and lightfast dark blue R salt, respectively, where: (e1) PP-BPDA-red, (e2) PP-BPDA-black, and (e3) PP-BPDA-blue.

[0035] Figure 7 This is a photograph of the nonwoven fabric PP-BPDA-Q-DPM12 after photochemical modification in Example 2.

[0036] Figure 8 The images show photographs e4 / e5 / e6 of the nonwoven fabric materials after PP-BPDA-Q-DPM12 was colored with red RC salt, lightfast black K salt, and lightfast dark blue R salt, respectively, in Example 2. Wherein: (e4) PP-BPDA-Q-DPM12 - Red, (e5) PP-BPDA-Q-DPM12 - Black, (e6) PP-BPDA-Q-DPM12 - Blue.

[0037] Figure 9 Photograph of the nonwoven fabric PP-Q-DPM12 modified with only N,N-dimethyl-N,N-di(dodecyl)methylene benzophenone quaternary ammonium salt in Comparative Example 1.

[0038] Figure 10 The images show f1 / f2 / f3 of the nonwoven fabric materials of PP-Q-DPM12 after being colored with Red RC salt, Lightfast Black K salt, and Lightfast Dark Blue R salt in Comparative Example 1. Wherein: (f1) PP-Q-DPM12-Red, (f2) PP-Q-DPM12-Black, (f3) PP-Q-DPM12-Blue.

[0039] Figure 11 The images show f4 / f5 / f6 of the nonwoven fabric materials after PP-PDA in Comparative Example 2 was colored with Red RC salt, Lightfast Black K salt, and Lightfast Dark Blue R salt. Wherein: (f4) PP-PDA - Red, (f5) PP-PDA - Black, (f6) PP-PDA - Blue.

[0040] Figure 12 XPS spectra of different samples in Experimental Example 1.

[0041] Figure 13 The images shown are photographs e7 / e8 / e9 of the nonwoven fabric material PP-BPDA-Q-DPM12 from Example 2 of Test Example 2, which was repeatedly washed after being colored with Red RC salt, Lightfast Black K salt, and Lightfast Dark Blue R salt. Specifically: (e7) PP-BPDA-Q-DPM12 - Red, (e8) PP-BPDA-Q-DPM12 - Black, (e9) PP-BPDA-Q-DPM12 - Blue. Detailed Implementation

[0042] Polypropylene fiber nonwoven fabric is mainly composed of polypropylene fibers, with the following chemical structure:

[0043] .

[0044] Polypropylene fibers are highly hydrophobic and have high crystallinity. During the dyeing process of nonwoven fabrics, the dye molecules have difficulty penetrating, resulting in low dye uptake and poor color fastness of polypropylene fibers.

[0045] This invention uses polydopamine to hydrophilically modify polypropylene nonwoven fabric, improving its surface properties and enhancing dyeing uniformity and binding ability with dyes during subsequent dyeing processes. However, the polydopamine-modified nonwoven fabric exhibits an overall brown color, which severely interferes with the subsequent dyeing process. This invention employs sodium borohydride to reduce and decolorize the polydopamine-modified polypropylene nonwoven fabric. This not only solves the decolorization problem of polydopamine-modified polypropylene nonwoven fabric but also effectively removes the brown hue while preserving the active functional groups on the polypropylene nonwoven fabric surface, maintaining its good surface properties and structure, and improving the dyeing effect.

[0046] The activated coloring method for polypropylene nonwoven fabric of the present invention includes the following steps:

[0047] Polypropylene nonwoven fabric is modified with polydopamine, then decolorized using sodium borohydride, and finally colored with a dye solution.

[0048] Dopamine is an endogenous nitrogen-containing organic compound, abbreviated as DA, with the following chemical structure:

[0049] .

[0050] Dopamine molecules can spontaneously polymerize to form polydopamine (PDA) through an oxidation reaction under weakly alkaline conditions (such as Tris-HCl buffer at pH 8.5).

[0051] Therefore, in one or more preferred embodiments, the polypropylene nonwoven fabric is modified with polydopamine as follows:

[0052] Polypropylene nonwoven fabric is soaked in Tris-HCl buffer solution of dopamine and reacted at 20-30℃. Reaction temperatures include 22℃, 25℃, and 27℃.

[0053] Preferably, the pH of the Tris-HCl buffer is 8.5, and the concentration of the dopamine Tris-HCl buffer is 1-3 mg / mL, such as 1.5 mg / mL, 2 mg / mL, 2.5 mg / mL, etc.

[0054] Preferably, the reaction time is 10-30 hours. After the reaction is completed, the product is washed with deionized water and dried to obtain polydopamine-modified polypropylene nonwoven fabric.

[0055] According to the present invention, after the polypropylene nonwoven fabric is modified with polydopamine, the nonwoven fabric is brown in color and needs to be reduced and decolored using sodium borohydride.

[0056] In one or more preferred embodiments, the concentration of the sodium borohydride solution during the reduction and decolorization process is 0.05-0.2 mol / L, for example: 0.06 mol / L, 0.08 mol / L, 0.1 mol / L, 0.15 mol / L;

[0057] Preferably, the reduction and decolorization time is 10-30 hours.

[0058] According to the present invention, the dye is a commonly used dye in the fabric industry, preferably a diazonium salt dye.

[0059] In one or more preferred embodiments, the dye is a solid red RC salt, a fast black K salt, or a fast dark blue R salt. The chemical structures of the solid red RC salt, fast black K salt, or fast dark blue R salt are as follows:

[0060] .

[0061] According to the present invention, the dye is dissolved in a solvent for coloring.

[0062] In one or more preferred embodiments, the dye solution is an acetone-water solution of the dye, with a volume ratio of acetone to water of 1:1; preferably, the concentration of the dye solution is 0.01-0.02 mol / L.

[0063] According to the present invention, after modification with polydopamine and decolorization with sodium borohydride, the polypropylene nonwoven fabric can be further modified with benzophenone quaternary ammonium salt compound and then dyed, which can improve the color fastness of polypropylene nonwoven fabric.

[0064] Therefore, in one or more preferred embodiments, after reduction and decolorization, the product is further modified using a benzophenone quaternary ammonium salt compound, and then colored using a dye solution.

[0065] Benzophenone (BP), a commonly used photoinitiator, absorbs ultraviolet light with wavelengths of 290–360 nm. Under ultraviolet irradiation, benzophenone molecules are photoexcited and enter the excited singlet state, subsequently transforming into the excited triplet state via intersystem crossing. The excited state of benzophenone possesses hydrogen abstraction capabilities, allowing it to abstract active hydrogen from the surface of nonwoven fabrics or polydopamine molecules, generating free radicals that modify the material surface.

[0066] The structural formula of benzophenone is as follows:

[0067] .

[0068] This invention is based on " "This refers to polypropylene fiber or polydopamine-modified polypropylene fiber. The chemical structure of the polypropylene fiber or polydopamine-modified polypropylene fiber after modification with benzophenone groups is as follows:"

[0069] .

[0070] According to the present invention, for diazonium salt dyes, the chemical structure contains a diazonium salt structure, which can be combined with quaternary ammonium salts through chemical bonds. Therefore, the present invention utilizes the above mechanism to further introduce a quaternary ammonium salt structure into the benzophenone structure, which can further improve color fastness during the coloring process of diazonium salt dyes through the chemical bond between the diazonium salt and the quaternary ammonium salt.

[0071] In one or more preferred embodiments, the benzophenone quaternary ammonium salt compound is N,N-dimethyl-N,N-di(dodecyl)methylene benzophenone quaternary ammonium salt.

[0072] N,N-Dimethyl-N,N-Di(dodecyl)methylene benzophenone quaternary ammonium salt can be obtained by brominating 4,4'-dimethylbenzophenone and then reacting it with N,N-dimethyldodecylamine.

[0073] The reaction mechanism is as follows:

[0074] .

[0075] In one or more preferred embodiments, the modification process using benzophenone quaternary ammonium salt compounds is as follows:

[0076] The decolorized polypropylene nonwoven fabric was soaked in an ethanol solution of benzophenone quaternary ammonium salt compound and then subjected to photochemical modification reaction by ultraviolet light irradiation.

[0077] Preferably, the concentration of the benzophenone quaternary ammonium salt compound ethanol solution is 0.02-0.03 g / mL.

[0078] According to the present invention, the mechanism by which diazonium salt dyes color nonwoven fabrics is as follows:

[0079] The benzene ring of polydopamine is an electron-donating group, which can undergo a coupling reaction with diazonium salts. The reaction mechanism is shown in the schematic diagram below. Figure 1 As shown.

[0080] The benzene ring in N,N-dimethyl-N,N-di(dodecyl)methylenebenzophenone quaternary ammonium salt is also an electron-donating group and can undergo coupling reactions with diazonium salt dyes. A schematic diagram of the reaction mechanism is shown below. Figure 2 As shown.

[0081] The present invention will be further described below with reference to specific embodiments and accompanying drawings, but is not limited thereto.

[0082] The N,N-dimethyl-N,N-di(dodecyl)methylene benzophenone quaternary ammonium salt used in the examples was prepared according to the following steps:

[0083] Using 4,4'-dimethylbenzophenone (1.576 g, 8 mmol), N-bromosuccinimide (1.896 g, 4 mmol), and azobisisobutyronitrile (0.636 g, 6 mmol) as starting materials, carbon tetrachloride was added and mixed thoroughly. The mixture was then heated to 85 °C and refluxed for 24 h. After the reaction was completed, the solvent was removed by rotary evaporation. The crude product was purified by silica gel column chromatography, eluted with a mixed solvent of n-hexane and ethyl acetate (20:1), to give a white solid product 1 (bis(4-bromomethylphenyl) ketone), yield (53.77%).

[0084] Product 1: δH 1H NMR (400 MHz, CDCl3): 5.08-5.14 (s, 4H), 7.80-7.90 (s, 2H), 8.06-8.12 (d, 2H), 8.24-8.28 (d, 1H), 8.32-8.41 (q, 3H).

[0085] Product 1 (0.2 g, 0.543 mmol) was placed in a round-bottom flask and dissolved in ethyl acetate. Then, N,N-dimethyldodecylamine (0.147 g, 0.688 mmol) / (0.231, 086 mmol) was added, and the mixture was protected with N2 for 10 min and gently refluxed at 85 °C for 12 h. After the reaction was complete, ethyl acetate was removed by rotary evaporation under vacuum. The reactants were ultrasonically washed with an organic solvent (n-hexane:ethyl acetate = 10:1), and the solution was centrifuged. The resulting product was dried at 60 °C to give a white waxy solid product 2 (N,N-dimethyl-N,N-di(dodecyl)methylenebenzophenone quaternary ammonium salt), yield (79.70%) (denoted as Q-DPM12).

[0086] Product 2: δH 1H NMR (400 MHz, CD3OD): 0.82-0.90 (d, 6H), 1.20-1.45 (m, 36H), 1.80-1.96 (m, 4H), 3.04-3.11 ( s, 12), 3.33-3.43 (m, 4H), 4.63-4.68 (s, 4H), 7.73-7.78 (d, 4H), 7.89-7.94 (d, 4H).

[0087] Example 1

[0088] The activation and coloring method for polypropylene nonwoven fabric includes the following steps:

[0089] (1) Polydopamine modification and activation of nonwoven fabrics

[0090] Disposable medical mask filter elements (PP) were cut into squares, ultrasonically cleaned with anhydrous ethanol and deionized water respectively, and then dried. A Tris-HCl buffer solution (pH=8.5) was prepared using potassium dihydrogen phosphate and disodium hydrogen phosphate, with a small amount of ethanol added. A 2 mg / mL dopamine solution was then prepared using this solution. The cleaned PP nonwoven fabric was immersed in the newly prepared dopamine buffer solution and reacted in a 25°C water bath shaker for 24 hours. After 24 hours, the fabric was removed, ultrasonically cleaned with deionized water, dried in a 60°C oven, and labeled as PP-PDA.

[0091] (2) Reduction decolorization of activated nonwoven fabric

[0092] PP-PDA was immersed in a 0.1 mol / L sodium borohydride solution and shaken at room temperature for 24 h. The reduced PP-PDA was then washed with deionized water to obtain the decolorized material, which was labeled as PP-BPDA.

[0093] (3) Coloring of PP-BPDA

[0094] PP-BPDA was immersed in 0.01M solid red RC salt / fast black K salt / fast dark blue R salt in acetone / water (1:1) for 24 hours at room temperature. Then, the dyed nonwoven fabric was ultrasonically cleaned with acetone to obtain materials e1 / e2 / e3.

[0095] Photos of untreated disposable medical mask filter cartridges (PP), such as... Figure 3 As shown; a photograph of nonwoven PP-PDA modified and activated with polydopamine, as shown. Figure 4 As shown; a restored photo of the decolorized nonwoven fabric PP-BPDA, as shown. Figure 5 As shown; photos of PP-BPDA nonwoven fabric materials e1 / e2 / e3 after being colored with Red RC salt / Lightfast Black K salt / Lightfast Dark Blue R salt respectively, as shown. Figure 6 As shown.

[0096] Depend on Figure 3-5 It is known that the nonwoven fabric modified and activated by polydopamine exhibits an overall brown color, and this brown coating severely interferes with the subsequent dyeing process. After reduction and decolorization, the brown color disappears, effectively removing the brown hue.

[0097] Depend on Figure 6 The dyeing characteristics of different nonwoven fabric samples show that the coloring of nonwoven fabrics by different diazonium salt dyes can be clearly and accurately distinguished, including the coloring depth, uniformity, and hue, and the coloring is uniform.

[0098] Example 2

[0099] The activation and coloring method for polypropylene nonwoven fabric includes the following steps:

[0100] (1) Polydopamine (PDA) modification and activation of nonwoven fabrics

[0101] Disposable medical mask filter elements (PP) were cut into squares, ultrasonically cleaned with anhydrous ethanol and deionized water respectively, and then dried. A Tris-HCl buffer solution (pH=8.5) was prepared using potassium dihydrogen phosphate and disodium hydrogen phosphate, with a small amount of ethanol added. A 2 mg / mL dopamine solution was then prepared using this solution. The cleaned PP nonwoven fabric was immersed in the newly prepared dopamine buffer solution and reacted in a 25 ℃ constant temperature water bath shaker for 24 h. After 24 h, the fabric was removed, ultrasonically cleaned with deionized water, dried in a 60 ℃ oven, and labeled as PP-PDA.

[0102] (2) Reduction decolorization of activated nonwoven fabric

[0103] PP-PDA was immersed in a 0.1 mol / L sodium borohydride solution and shaken at room temperature for 24 h. The reduced PP-PDA was then washed with deionized water to obtain the decolorized material, which was labeled as PP-BPDA.

[0104] (3) Photochemical modification of decolorized nonwoven fabric

[0105] PP-BPDA was immersed in an ethanol solution (0.025 g / mL) of N,N-dimethyl-N,N-di(dodecyl)methylenebenzophenone quaternary ammonium salt for 5 min, and then dried at 40 °C. The sample was irradiated with ultraviolet light for 20 min, with the sample being turned over at 10 min. Finally, the nonwoven fabric was ultrasonically cleaned with ethanol and labeled as PP-BPDA-Q-DPM12.

[0106] (4) Coloring of PP-BPDA-Q-DPM12

[0107] The nonwoven fabric modified with N,N-dimethyl-N,N-di(dodecyl)methylene benzophenone quaternary ammonium salt was immersed in 0.01M solid red RC salt / fast black K salt / fast dark blue R salt in acetone / water (1:1) at room temperature for 24 hours. Then, the dyed nonwoven fabric was ultrasonically cleaned with acetone to obtain materials e4 / e5 / e6.

[0108] The nonwoven fabric is first modified with polydopamine, followed by a reduction and decolorization step to remove any color that may have been introduced during the polydopamine modification process, restoring the nonwoven fabric to a relatively pure base state. Then, a benzophenone-type quaternary ammonium salt is used to further modify the treated nonwoven fabric. After this series of treatments, the nonwoven fabric ultimately achieves a relatively ideal dyeing effect.

[0109] Photographs of the photochemically modified nonwoven fabric PP-BPDA-Q-DPM12 are shown below. Figure 7 As shown. Photos of PP-BPDA-Q-DPM12 nonwoven fabric materials after being colored with Red RC salt, Lightfast Black K salt, and Lightfast Dark Blue R salt, respectively, at levels e4 / e5 / e6. Figure 8 As shown. By Figure 8 By carefully observing the dyeing characteristics of different nonwoven fabric samples, it is possible to clearly and accurately distinguish the coloring of nonwoven fabrics by different diazonium salt dyes, including differences in coloring depth, uniformity, and hue, and the coloring is uniform.

[0110] Comparative Example 1

[0111] (1) Quaternization modification of nonwoven fabrics

[0112] Nonwoven fabric (PP) was immersed in an ethanol solution (0.025 g / mL) of N,N-dimethyl-N,N-di(dodecyl)methylene benzophenone quaternary ammonium salt for 5 min, then dried at 40 °C. The sample was irradiated with ultraviolet light for 20 min, with the sample being turned over at 10 min intervals. Finally, the nonwoven fabric was ultrasonically cleaned with ethanol and labeled as PP-Q-DPM12.

[0113] (2) Coloring of PP-Q-DPM12

[0114] The nonwoven fabric modified with only N,N-dimethyl-N,N-di(dodecyl)methylene benzophenone quaternary ammonium salt was immersed in 0.01M solid red RC salt / fast black K salt / fast dark blue R salt in acetone / water (1:1) for 24 hours at room temperature. Then, the dyed nonwoven fabric was ultrasonically cleaned with acetone to obtain materials f1 / f2 / f3.

[0115] Photos of PP-Q-DPM12 nonwoven fabric modified with N,N-dimethyl-N,N-di(dodecyl)methylene benzophenone quaternary ammonium salt are shown below. Figure 9 As shown.

[0116] Photos of PP-Q-DPM12 nonwoven fabric material after being colored with Red RC salt / Lightfast Black K salt / Lightfast Dark Blue R salt (f1 / f2 / f3). Figure 10 As shown.

[0117] Depend on Figure 10 It is evident that two significant phenomena emerged after direct modification of nonwoven fabrics with benzophenone-based quaternary ammonium salts. Firstly, the modified nonwoven fabrics exhibited uneven dyeing during the dyeing process, due to the uneven distribution of the chemical substances on the fabric surface. Secondly, when different diazonium salts were used for dyeing, similar dyeing results were observed; that is, the colors of nonwoven fabrics dyed with different diazonium salts were difficult to distinguish. This indicates that treating nonwoven fabrics solely with diazonium salts cannot achieve the desired dyeing effect.

[0118] Comparative Example 2

[0119] (1) Polydopamine modification and activation of nonwoven fabrics

[0120] The nonwoven fabric was activated and labeled as PP-PDA according to step (1) of Example 1.

[0121] (2) Coloring of PP-PDA

[0122] The polydopamine-activated nonwoven fabric PP-PDA was immersed in 0.01M solid red / fast black K salt / fast dark blue R salt in acetone / water (1:1) for 24 hours at room temperature. Then, the dyed nonwoven fabric was ultrasonically cleaned with acetone to obtain materials f4 / f5 / f6.

[0123] Photos of PP-PDA nonwoven fabric materials after being colored with Red RC salt / Lightfast Black K salt / Lightfast Dark Blue R salt (f4 / f5 / f6). Figure 11 As shown.

[0124] Depend on Figure 11 The dyeing effect is clearly observable, demonstrating that the polydopamine-modified coating plays a significant role in the nonwoven fabric coloring process, effectively preventing uneven coloring. However, when using lightfast black K salt and lightfast dark blue R salt to color the polydopamine-modified nonwoven fabric, the resulting colors are extremely similar, making them difficult to distinguish with the naked eye.

[0125] Experimental Example 1

[0126] To further investigate the chemical structural changes during the activation, decolorization, and surface modification processes of nonwoven fabrics, a detailed analysis of the XPS involved in the relevant processes of Example 2 was conducted, such as... Figure 12 As shown.

[0127] The XPS spectrum of the original nonwoven fabric clearly shows a distinct C1s peak, indicating that carbon dominates the surface of the fabric. Further analysis of the elemental composition reveals that C, N, and O account for 96.89%, 2.7%, and 0.43% respectively, indicating that the main component of the original nonwoven fabric surface is carbon-containing material, with relatively low levels of nitrogen and oxygen.

[0128] After polydopamine modification, the surface chemical structure of the nonwoven fabric underwent significant changes. A distinct O1s peak was clearly observed in the XPS spectra, indicating a substantial increase in oxygen content on the modified fabric surface. The proportions of C, N, and O became 83.2%, 4.28%, and 12.52%, respectively. Compared to the original nonwoven fabric, the oxygen and nitrogen content increased significantly, demonstrating that polydopamine successfully adhered to the nonwoven fabric surface, altering its surface chemical composition.

[0129] Subsequently, the polydopamine-modified nonwoven fabric was subjected to sodium borohydride reduction treatment to remove the brown color exhibited by the polydopamine-modified nonwoven fabric. Further analysis of XPS data revealed that the O1s and N1s peaks remained, and the proportions of C, N, and O were 84.86%, 3.13%, and 12.01%, respectively. This result is similar to the elemental proportions of the polydopamine-modified nonwoven fabric, demonstrating that while the sodium borohydride reduction decolorization step removed the brown color from the nonwoven fabric surface, it did not completely destroy the chemical structure imparted to the nonwoven fabric surface by polydopamine. Aromatic rings still remain on the nonwoven fabric surface, providing a basis for subsequent dyeing.

[0130] Based on this, the surface of the nonwoven fabric was photochemically modified with benzophenone quaternary ammonium salt. After modification with benzophenone quaternary ammonium salt, PP-BPDA-Q-DPM12 showed a clear bromine peak in the XPS spectrum, indicating that the benzophenone quaternary ammonium salt was successfully grafted onto the nonwoven fabric surface. At this point, the proportions of C, N, O, and Br were 77.23%, 2.44%, 18.22%, and 2.11%, respectively, further confirming the success of the modification. This modification provides active groups for subsequent re-dyeing of the nonwoven fabric, allowing dye molecules to better bind to the nonwoven fabric surface and achieve effective coloring.

[0131] Overall, polydopamine successfully activated the surface of the nonwoven fabric. Sodium borohydride removed the brown color while retaining some of the active functional groups imparted to the nonwoven fabric surface by polydopamine. Subsequently, the nonwoven fabric surface was photochemically modified with benzophenone quaternary ammonium salt, providing key active groups for the subsequent re-dyeing of the nonwoven fabric. This series of modification steps provides new ideas and methods for the dyeing technology of nonwoven fabrics.

[0132] Experimental Example 2

[0133] To verify the color fastness of dyed nonwoven fabric, the washing process was simulated by repeatedly washing with ethanol (5 times, 5 minutes each time) to verify the color fastness of the dyed nonwoven fabric.

[0134] In this experimental example, the nonwoven fabric material of PP-BPDA-Q-DPM12 from Example 2, after being colored with red RC salt / lightfast black K salt / lightfast dark blue R salt, was repeatedly washed. Photos of the washed material (e7 / e8 / e9) are shown below. Figure 13 As shown. By Figure 8 , Figure 13As can be seen, the nonwoven fabric material of PP-BPDA-Q-DPM12 in Example 2, after being colored with RC salt for solid red, K salt for fast black, and R salt for fast dark blue, showed no significant changes before and after washing. This indicates that the nonwoven fabric modified with benzophenone-type quaternary ammonium salts has surface-active sites or forms chemical bonds on the material surface, significantly improving the adsorption and fixation ability of the nonwoven fabric for diazonium salt dyes, thereby giving it excellent wash fastness performance.

Claims

1. A method for activating and coloring polypropylene nonwoven fabric, comprising the following steps: Polypropylene nonwoven fabric is modified with polydopamine, then decolorized using sodium borohydride, and finally colored with a dye solution.

2. The activation and coloring method for polypropylene nonwoven fabric according to claim 1, characterized in that, The modification process of polypropylene nonwoven fabric using polydopamine is as follows: Polypropylene nonwoven fabric was soaked in Tris-HCl buffer solution of dopamine and reacted at 20-30℃.

3. The activation and coloring method for polypropylene nonwoven fabric according to claim 2, characterized in that, The pH of the Tris-HCl buffer is 8.5, and the concentration of dopamine in the Tris-HCl buffer is 1-3 mg / mL. Preferably, the reaction time is 10-30 hours. After the reaction is completed, the product is washed with deionized water and dried to obtain polydopamine-modified polypropylene nonwoven fabric.

4. The activation and coloring method for polypropylene nonwoven fabric according to claim 1, characterized in that, The concentration of sodium borohydride solution during the reduction decolorization process is 0.05-0.2 mol / L; Preferably, the reduction and decolorization time is 10-30 hours.

5. The activation and coloring method for polypropylene nonwoven fabric according to claim 1, characterized in that, The dye is a diazonium salt dye, preferably a fixed red RC salt, a fast black K salt, or a fast dark blue R salt.

6. The activation and coloring method for polypropylene nonwoven fabric according to claim 1, characterized in that, The dye solution is an acetone-water solution of the dye, with a volume ratio of acetone to water of 1:

1.

7. The activation and coloring method for polypropylene nonwoven fabric according to claim 1, characterized in that, The concentration of the dye solution is 0.01-0.02 mol / L.

8. The method for activating and coloring polypropylene nonwoven fabric according to any one of claims 1-7, characterized in that, After reduction and decolorization, the compound is further modified using benzophenone quaternary ammonium salt, and then colored using a dye solution.

9. The activation and coloring method for polypropylene nonwoven fabric according to claim 8, characterized in that, The benzophenone quaternary ammonium salt compound is N,N-dimethyl-N,N-di(dodecyl)methylene benzophenone quaternary ammonium salt.

10. The method for activating and coloring polypropylene nonwoven fabric according to claim 8, characterized in that, The modification process is as follows: The decolorized polypropylene nonwoven fabric was soaked in an ethanol solution of benzophenone quaternary ammonium salt compound and then subjected to photochemical modification reaction by ultraviolet light irradiation. Preferably, the concentration of the benzophenone quaternary ammonium salt compound ethanol solution is 0.02-0.03 g / mL.

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