Asymmetric comb-shaped waterborne polyurethane-based protective coating as well as preparation method and application thereof

Abstract

The invention relates to a protective coating based on asymmetric comb-shaped waterborne polyurethane as well as a preparation method and application thereof, and the method comprises the following steps: mixing polyethylene glycol, isophorone diisocyanate and N, N-dimethylformamide, and reacting in a nitrogen atmosphere to obtain a prepolymer; adding a fluorine-containing monomer chain extender, 2-hydroxyethyl disulfide, 2-methyl-2-acrylic acid-2, 3-dihydroxy propyl ester and 2, 2-dimethylolpropionic acid into the prepolymer, and carrying out a reaction; then adding amino beta-cyclodextrin, after the reaction is finished, neutralizing with triethylamine to form salt, adding water, emulsifying to obtain waterborne polyurethane emulsion, coating the surface of a base material with the waterborne polyurethane emulsion, and curing to obtain the protective coating. The coating not only can provide physical barrier protection in an extreme humid environment and an acid-base corrosive medium, but also can relieve the pressure of toxic and harmful volatile gas compounds VOCs on the environment, and also can ensure the long-term stability of a coating material through a self-repairing effect, so that the protection effect and the service life of the coating are further improved.

Description

Technical Field

[0001] This invention belongs to the field of chemical protection of textile surfaces, specifically relating to an asymmetric comb-shaped waterborne polyurethane protective coating, its preparation method, and its application. Background Technology

[0002] In fields such as military, chemical engineering, and environmental remediation, VOCs, extremely humid environments, and acidic and alkaline corrosive media pose significant threats to personnel safety and equipment durability, urgently requiring the development of highly protective and multifunctional coating materials capable of withstanding complex and variable environments. Protective systems such as chemical protective suits and industrial equipment coatings not only need to provide physical barriers for workers but also require certain dynamic environmental adaptability characteristics under long-term exposure to harsh environments.

[0003] While traditional solvent-based polyurethane coatings are widely used in protective applications, they typically offer limited functionality, focusing primarily on single functions such as hydrophobicity or corrosion resistance. Furthermore, the manufacturing processes of these coatings often involve the emission of volatile organic solvents, failing to meet environmental sustainability requirements and highlighting a key limitation in meeting the long-term demand for environmentally friendly and multifunctional protective materials. Therefore, it is essential to develop waterborne polyurethane coatings that can achieve protective effects under extreme conditions while also being environmentally friendly. These coatings should protect substrates in humid, acidic, alkaline, or volatile gas environments and ensure the long-term stability and service life of the coating material through self-healing properties. Summary of the Invention

[0004] Technical problem solved: Addressing the issue that existing solvent-based polyurethane coatings cannot achieve both protective effects and environmental friendliness under extreme conditions, this invention proposes an asymmetric comb-like waterborne polyurethane protective coating, its preparation method, and its application. Due to its unique asymmetric molecular chain segment structure design, the prepared protective coating not only provides corrosion protection to the substrate but also effectively adsorbs harmful gases in the environment, providing safety protection for workers. It can protect the substrate in humid, acidic, alkaline, or volatile gas environments and also ensures the long-term stability and service life of the coating material through self-healing.

[0005] Technical solution: The first objective of this invention is to propose a method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating, which, by weight, includes the following steps:

[0006] Step 1: Mix 6-18 parts of polyethylene glycol, 7-21 parts of isophorone diisocyanate and 10-30 parts of N,N-dimethylformamide, and react at 75°C for 2-6 hours under a nitrogen atmosphere to obtain a prepolymer;

[0007] Step 2: Add 5-15 parts of fluorinated monomer chain extender, 0.5-3 parts of 2-hydroxyethyl disulfide, 0.5-3 parts of 2-methyl-2-acrylate-2,3-dihydroxypropyl ester and 0.5-3 parts of 2,2-dimethylolpropionic acid to the above prepolymer, and continue the reaction at 80°C for 6-18 hours to obtain reaction solution A;

[0008] Step 3: Add 0.5-6 parts of aminoβ-cyclodextrin to reaction solution A and continue the reaction at 70°C for 3-9 hours. After the reaction is completed, triethylamine is neutralized to form a salt, deionized water is added, and emulsification is performed to obtain a waterborne polyurethane emulsion. After coating on the substrate surface and curing, an asymmetric comb-shaped waterborne polyurethane protective coating is obtained.

[0009] Preferably, the molecular weight of the polyethylene glycol in step one is 600.

[0010] Preferably, the fluorinated monomer chain extender in step two is dihydroxy-modified tridecylfluorooctyl methacrylate, which is prepared as follows: by weight, 4-12 parts of tridecylfluorooctyl methacrylate and 3-9 parts of thioglycerol are dissolved in 10-30 parts of dichloromethane and 0.01-0.05 parts of photoinitiator. After thorough mixing, the mixture is reacted under ultraviolet light at 365 nm at room temperature for 4-8 hours. After rotary evaporation, it is dissolved in water, extracted with dichloromethane, and dried to obtain an oily liquid fluorinated long-chain chain extender.

[0011] Preferably, the photoinitiator is benzoin dimethyl ether.

[0012] Preferably, the amino-β-cyclodextrin in step three is a monoamino-modified β-cyclodextrin, which is prepared as follows: by weight, 50-150 parts of β-CD and 15-45 parts of 4-toluenesulfonyl chloride are reacted at room temperature under alkaline conditions for 24 hours with water as the solvent. The filtrate is collected by static filtration, the pH is adjusted to 8 with ammonium chloride, and the mixture is cooled and crystallized at 4°C. The mixture is then filtered and dried to obtain mono-6-oxo-(p-toluenesulfonyl)-β-cyclodextrin powder. 5-15 parts of the above product are taken and treated with 50-150 parts of 28% ammonia water at 75°C. After cooling, acetone is precipitated and the mixture is filtered to obtain white powder 6-amino-6-deoxy-β-cyclodextrin.

[0013] Preferably, the curing conditions in step three are: curing temperature of 40-80℃ and curing time of 12-48 hours.

[0014] Preferably, the thickness of the asymmetric comb-shaped waterborne polyurethane protective coating in step three is 1-200 μm.

[0015] The second objective of this invention is to propose an asymmetric comb-shaped waterborne polyurethane protective coating prepared based on the above method.

[0016] The third objective of this invention is to propose the application of an asymmetric comb-shaped waterborne polyurethane protective coating, as described above, in the preparation of anti-corrosion fabrics.

[0017] The fourth objective of this invention is to propose the application of an asymmetric comb-shaped waterborne polyurethane protective coating as a protective coating against toxic and harmful gases.

[0018] Beneficial effects:

[0019] (1) The polyurethane protective coating prepared by the present invention has excellent anti-fouling and corrosion resistance. When it is polluted or corroded by the outside world, the long fluorine chains that migrate and accumulate on the surface of the coating can reduce the surface energy and isolate the corrosive medium on the surface of the coating, thereby providing effective protection for the inside of the coating and the substrate fabric.

[0020] (2) This invention uses β-cyclodextrin as a side linker to polyurethane, and utilizes the unique cavity structure of β-cyclodextrin to give the protective coating good adsorption performance and capture VOCs in the air.

[0021] (3) Based on the asymmetric comb structure, the present invention utilizes the host-guest interaction between the β-cyclodextrin of the polyurethane side chain and the fluorine long chain (the interaction between the hydrophobic cavity of β-cyclodextrin and the fluorine long chain) to synergize with the disulfide monomer in the main chain, so that the coating can have excellent self-healing properties and achieve precise and rapid self-healing effect when damaged by external factors. Attached Figure Description

[0022] Figure 1 Fourier transform infrared spectra (A) of the asymmetric comb-shaped waterborne polyurethane protective coatings in Examples 1-4 and nuclear magnetic resonance hydrogen spectrum (B) of Example 2;

[0023] Figure 2 The image shows an SEM image of the asymmetric comb-shaped waterborne polyurethane protective coating fabric in Example 2. In the image, (A) shows the surface morphology of the coated fabric under a scanning electron microscope, and (B) shows the surface element distribution of the coated fabric under X-rays.

[0024] Figure 3 The images show the water and diiodomethane contact angle test diagram (A) and surface energy test diagram (B) of the asymmetric comb-shaped waterborne polyurethane protective coating fabric in the embodiments.

[0025] Figure 4 The image shows the anti-fouling effect of the asymmetric comb-shaped waterborne polyurethane protective coating fabric against three pollutants: soy sauce, red wine, and cola in Example 2. In the image, (A) is a morphological diagram of water, soy sauce, red wine, and cola, and (B) is a diagram showing the anti-fouling effect of soy sauce, red wine, and cola on the original fabric and after the coating is applied.

[0026] Figure 5The images show the acid and alkali corrosion resistance of the asymmetric comb-shaped waterborne polyurethane protective coating fabric in Example 2 (each column, from left to right, shows the fabric surface morphology after 0 min, 30 min, 60 min, 90 min, and after complete drying).

[0027] Figure 6 The figure shows the adsorption test curves of the asymmetric comb-shaped waterborne polyurethane protective coating fabric for volatile organic gases of different properties in Example 2. Figure A is the adsorption capacity of the coated fabric for four volatile organic compounds: ammonia, acetic acid, limonene and formaldehyde. Figures B and C are the adsorption amount and removal rate curves of the coated fabric for formaldehyde.

[0028] Figure 7 The images show optical microscope images of the asymmetric comb-shaped waterborne polyurethane protective coating before and after repair under different degrees of damage in Examples 2, Comparative Examples 1 and 2. In the images, (A) corresponds to Example 2, (B) corresponds to Comparative Example 1, and (C) corresponds to Comparative Example 2. Detailed Implementation

[0029] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0030] Unless otherwise specified, the technical means used in the following embodiments are all conventional means well known to those skilled in the art, and the experimental methods without specific conditions are all conventional methods in the art.

[0031] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0032] One embodiment of the present invention provides a method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating, the specific steps of which are as follows:

[0033] (1) Preparation of fluorinated monomer chain extenders, the reaction formula is shown in Formula I below:

[0034] (I)

[0035] Dissolve 4-12 parts of tridecafluorooctyl methacrylate and 3-9 parts of thioglycerol in 10-30 parts of dichloromethane, add 0.01-0.05 parts of benzoin dimethyl ether as a photoinitiator, mix thoroughly, and react under 365 nm ultraviolet light at room temperature for 4-8 hours. After rotary evaporation, dissolve in water, extract with dichloromethane and dry to obtain an oily liquid fluorinated long-chain chain extender (fluorinated monomer chain extender).

[0036] (2) Preparation of amino-β-cyclodextrin (mono-amino modified β-cyclodextrin), the reaction formula is shown in Formula II below:

[0037] (II)

[0038] 50-150 parts of β-CD and 15-45 parts of 4-toluenesulfonyl chloride were reacted under alkaline conditions at room temperature for 24 hours using water as the solvent. The mixture was allowed to stand, filtered, and the filtrate was collected. The pH was adjusted to 8 with ammonium chloride, and the mixture was cooled at 4°C to crystallize. The crystals were then filtered and dried to obtain mono-6-oxo-(p-toluenesulfonyl)-β-cyclodextrin powder. 5-15 parts of the above product were taken and treated with 50-150 parts of 28 wt% ammonia water at 75°C. After cooling, the product was precipitated with acetone and filtered to obtain a white powder of 6-amino-6-deoxy-β-cyclodextrin.

[0039] (3) Preparation of protective waterborne polyurethane:

[0040] 6-18 parts of polyethylene glycol with a molecular weight of 600, 7-21 parts of isophorone diisocyanate, and 10-30 parts of N,N-dimethylformamide are mixed and reacted at 75°C for 2-6 hours under a nitrogen atmosphere to obtain a prepolymer. 5-15 parts of a fluorinated monomer chain extender, 0.5-3 parts of 2-hydroxyethyl disulfide, 0.5-3 parts of 2-methyl-2-acrylate-2,3-dihydroxypropyl ester, and 0.5-3 parts of 2,2-dimethylolpropionic acid are added to the prepolymer, and the reaction is continued at 80°C for 6-18 hours to obtain reaction solution A. Then, 0.5-6 parts of aminoβ-cyclodextrin are added to reaction solution A, and the reaction is continued at 70°C for 3-9 hours. After the reaction is complete, 0.5-3 parts of triethylamine are used to neutralize and form a salt, and 40-120 parts of deionized water are added to emulsify and obtain an aqueous polyurethane emulsion. This emulsion is coated onto the substrate surface and cured to obtain an asymmetric comb-like aqueous polyurethane protective coating.

[0041] The specific implementation method is as follows:

[0042] Example 1

[0043] This embodiment provides a method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating, the specific steps of which are as follows:

[0044] (1) 4.3 g of tridecyl methacrylate and 3.2 g of thioglycerol were dissolved in 30 g of dichloromethane, and 0.01 g of benzoin dimethyl ether was used as a photoinitiator. After thorough mixing, the mixture was reacted for 6 hours under ultraviolet light at 365 nm at room temperature. After rotary evaporation, it was dissolved in water, extracted with dichloromethane and dried to obtain an oily liquid fluorine long-chain chain extender (fluorine monomer chain extender).

[0045] (2) 50 g of β-CD and 15 g of 4-toluenesulfonyl chloride were reacted under alkaline conditions at room temperature for 24 hours in 500 ml of water. The mixture was allowed to stand, filtered, and the filtrate was collected. The pH was adjusted to 8 with ammonium chloride and the mixture was cooled and crystallized at 4 °C. The crystals were then filtered and dried to obtain mono-6-oxo-(p-toluenesulfonyl)-β-cyclodextrin powder. 5 g of the above product was taken and treated with 100 ml of 28% ammonia water at 75 °C. After cooling, the product was precipitated with acetone and filtered to obtain a white powder of 6-amino-6-deoxy-β-cyclodextrin (aminoβ-cyclodextrin).

[0046] (3) Mix 6 g of polyethylene glycol with a molecular weight of 600, 7 g of isophorone diisocyanate and 10 g of N,N-dimethylformamide and react at 75°C for 2 hours under a nitrogen atmosphere to obtain a prepolymer; add 5.4 g of fluorinated monomer chain extender, 0.78 g of 2-hydroxyethyl disulfide, 0.8 g of 2-methyl-2-acrylate-2,3-dihydroxypropyl ester and 0.67 g of 2,2-dimethylolpropionic acid to the above prepolymer and continue to react at 80°C for 6 hours to obtain reaction solution A; then add 0.57 g of aminoβ-cyclodextrin to reaction solution A and continue to react at 70°C for 6 hours. After the reaction was completed, 0.5 g of triethylamine was used to neutralize and form a salt, and 40 g of deionized water was added to emulsify and obtain an aqueous polyurethane emulsion. This emulsion was coated on the surface of the substrate fabric and cured at 80°C for 24 hours to obtain an asymmetric comb-shaped aqueous polyurethane protective coating (denoted as ACWPU-1). The coating thickness was 200 μm ± 1 μm.

[0047] Example 2

[0048] This embodiment provides a method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating, the specific steps of which are as follows:

[0049] (1) 4.3 g of tridecyl methacrylate and 3.2 g of thioglycerol were dissolved in 30 g of dichloromethane, and 0.01 g of benzoin dimethyl ether was used as a photoinitiator. After thorough mixing, the mixture was reacted for 6 hours under ultraviolet light at 365 nm at room temperature. After rotary evaporation, it was dissolved in water, extracted with dichloromethane and dried to obtain an oily liquid fluorine long-chain chain extender (fluorine monomer chain extender).

[0050] (2) 50 g of β-CD and 15 g of 4-toluenesulfonyl chloride were reacted under alkaline conditions at room temperature for 24 hours in 500 ml of water. The mixture was allowed to stand, filtered, and the filtrate was collected. The pH was adjusted to 8 with ammonium chloride and the mixture was cooled and crystallized at 4 °C. The crystals were then filtered and dried to obtain mono-6-oxo-(p-toluenesulfonyl)-β-cyclodextrin powder. 5 g of the above product was taken and treated with 100 ml of 28% ammonia water at 75 °C. After cooling, the product was precipitated with acetone and filtered to obtain a white powder of 6-amino-6-deoxy-β-cyclodextrin (aminoβ-cyclodextrin).

[0051] (3) Mix 6 g of polyethylene glycol with a molecular weight of 600, 7 g of isophorone diisocyanate and 10 g of N,N-dimethylformamide and react at 75°C for 2 hours under a nitrogen atmosphere to obtain a prepolymer; add 5.4 g of fluorinated monomer chain extender, 0.78 g of 2-hydroxyethyl disulfide, 0.8 g of 2-methyl-2-acrylate-2,3-dihydroxypropyl ester and 0.67 g of 2,2-dimethylolpropionic acid to the above prepolymer and continue to react at 80°C for 6 hours to obtain reaction solution A; then add 1.14 g of aminoβ-cyclodextrin to reaction solution A and continue to react at 70°C for 6 hours. After the reaction was completed, 0.5 g of triethylamine was used to neutralize and form a salt, and 40 g of deionized water was added to emulsify and obtain an aqueous polyurethane emulsion. This emulsion was coated on the surface of the substrate fabric and cured at 80°C for 24 hours to obtain an asymmetric comb-shaped aqueous polyurethane protective coating (denoted as ACWPU-2). The coating thickness was 200 μm ± 1 μm.

[0052] Example 3

[0053] This embodiment provides a method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating, the specific steps of which are as follows:

[0054] (1) 4.3 g of tridecyl methacrylate and 3.2 g of thioglycerol were dissolved in 30 g of dichloromethane, and 0.01 g of benzoin dimethyl ether was used as a photoinitiator. After thorough mixing, the mixture was reacted for 6 hours under ultraviolet light at 365 nm at room temperature. After rotary evaporation, it was dissolved in water, extracted with dichloromethane and dried to obtain an oily liquid fluorine long-chain chain extender (fluorine monomer chain extender).

[0055] (2) 50 g of β-CD and 15 g of 4-toluenesulfonyl chloride were reacted under alkaline conditions at room temperature for 24 hours in 500 ml of water. The mixture was allowed to stand, filtered, and the filtrate was collected. The pH was adjusted to 8 with ammonium chloride and the mixture was cooled and crystallized at 4 °C. The crystals were then filtered and dried to obtain mono-6-oxo-(p-toluenesulfonyl)-β-cyclodextrin powder. 5 g of the above product was taken and treated with 100 ml of 28% ammonia water at 75 °C. After cooling, the product was precipitated with acetone and filtered to obtain a white powder of 6-amino-6-deoxy-β-cyclodextrin (aminoβ-cyclodextrin).

[0056] (3) Mix 6 g of polyethylene glycol with a molecular weight of 600, 7 g of isophorone diisocyanate and 10 g of N,N-dimethylformamide and react at 75°C for 2 hours under a nitrogen atmosphere to obtain a prepolymer; add 5.4 g of fluorinated monomer chain extender, 0.78 g of 2-hydroxyethyl disulfide, 0.8 g of 2-methyl-2-acrylate-2,3-dihydroxypropyl ester and 0.67 g of 2,2-dimethylolpropionic acid to the above prepolymer and continue to react at 80°C for 6 hours to obtain reaction solution A; then add 1.71 g of aminoβ-cyclodextrin to reaction solution A and continue to react at 70°C for 6 hours. After the reaction was completed, 0.5 g of triethylamine was used to neutralize and form a salt, and 40 g of deionized water was added to emulsify and obtain an aqueous polyurethane emulsion. This emulsion was coated on the surface of the substrate fabric and cured at 80°C for 24 hours to obtain an asymmetric comb-shaped aqueous polyurethane protective coating (denoted as ACWPU-3). The coating thickness was 200 μm ± 1 μm.

[0057] Example 4

[0058] A method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating, comprising the following steps:

[0059] (1) 4.3 g of tridecyl methacrylate and 3.2 g of thioglycerol were dissolved in 30 g of dichloromethane, and 0.01 g of benzoin dimethyl ether was used as a photoinitiator. After thorough mixing, the mixture was reacted for 6 hours under ultraviolet light at 365 nm at room temperature. After rotary evaporation, it was dissolved in water, extracted with dichloromethane and dried to obtain an oily liquid fluorine long-chain chain extender (fluorine monomer chain extender).

[0060] (2) 50 g of β-CD and 15 g of 4-toluenesulfonyl chloride were reacted under alkaline conditions at room temperature for 24 hours in 500 ml of water. The mixture was allowed to stand, filtered, and the filtrate was collected. The pH was adjusted to 8 with ammonium chloride and the mixture was cooled and crystallized at 4 °C. The crystals were then filtered and dried to obtain mono-6-oxo-(p-toluenesulfonyl)-β-cyclodextrin powder. 5 g of the above product was taken and treated with 100 ml of 28% ammonia water at 75 °C. After cooling, the product was precipitated with acetone and filtered to obtain a white powder of 6-amino-6-deoxy-β-cyclodextrin (aminoβ-cyclodextrin).

[0061] (3) Mix 6 g of polyethylene glycol with a molecular weight of 600, 7 g of isophorone diisocyanate and 10 g of N,N-dimethylformamide and react at 75°C for 2 hours under a nitrogen atmosphere to obtain a prepolymer; add 5.4 g of fluorinated monomer chain extender, 0.78 g of 2-hydroxyethyl disulfide, 0.8 g of 2-methyl-2-acrylate-2,3-dihydroxypropyl ester and 0.67 g of 2,2-dimethylolpropionic acid to the above prepolymer and continue to react at 80°C for 6 hours to obtain reaction solution A; then add 2.28 g of aminoβ-cyclodextrin to reaction solution A and continue to react at 70°C for 6 hours. After the reaction was completed, 0.5 g of triethylamine was used to neutralize and form a salt, and 40 g of deionized water was added to emulsify and obtain an aqueous polyurethane emulsion. This emulsion was coated on the surface of the substrate fabric and cured at 80°C for 24 hours to obtain an asymmetric comb-shaped aqueous polyurethane protective coating (denoted as ACWPU-4). The coating thickness was 200 μm ± 1 μm.

[0062] Comparative Example 1

[0063] This comparative example provides a method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating, the specific steps of which are as follows:

[0064] (1) 4.3 g of tridecyl methacrylate and 3.2 g of thioglycerol were dissolved in 30 g of dichloromethane, and 0.01 g of benzoin dimethyl ether was used as a photoinitiator. After thorough mixing, the mixture was reacted for 6 hours under ultraviolet light at 365 nm at room temperature. After rotary evaporation, it was dissolved in water, extracted with dichloromethane and dried to obtain an oily liquid fluorine long-chain chain extender (fluorine monomer chain extender).

[0065] (2) 6 g of polyethylene glycol with a molecular weight of 600, 7 g of isophorone diisocyanate and 10 g of N,N-dimethylformamide were mixed and reacted at 75°C for 2 hours under a nitrogen atmosphere to obtain a prepolymer. 5.4 g of fluorinated monomer chain extender, 0.9 g of 1,4-butanediol and 0.67 g of 2,2-dimethylolpropionic acid were added to the prepolymer, and the reaction was continued at 80°C for 6 hours to obtain reaction solution A. After the reaction was completed, 0.5 g of triethylamine was used to neutralize and form a salt, and 40 g of deionized water was added to emulsify and obtain an aqueous polyurethane emulsion. This emulsion was coated onto the surface of the substrate fabric and cured at 80°C for 24 hours to obtain an asymmetric comb-like aqueous polyurethane protective coating (denoted as FWPU). The coating thickness was 200 μm ± 1 μm.

[0066] Comparative Example 2

[0067] This embodiment provides a method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating, the specific steps of which are as follows:

[0068] (1) 4.3 g of tridecyl methacrylate and 3.2 g of thioglycerol were dissolved in 30 g of dichloromethane, and 0.01 g of benzoin dimethyl ether was used as a photoinitiator. After thorough mixing, the mixture was reacted for 6 hours under ultraviolet light at 365 nm at room temperature. After rotary evaporation, it was dissolved in water, extracted with dichloromethane and dried to obtain an oily liquid fluorine long-chain chain extender (fluorine monomer chain extender).

[0069] (2) 6 g of polyethylene glycol with a molecular weight of 600, 7 g of isophorone diisocyanate and 10 g of N,N-dimethylformamide were mixed and reacted at 75°C for 2 hours under a nitrogen atmosphere to obtain a prepolymer. 5.4 g of fluorinated monomer chain extender, 0.78 g of 2-hydroxyethyl disulfide, 0.8 g of 2-methyl-2-acrylate-2,3-dihydroxypropyl ester and 0.67 g of 2,2-dimethylolpropionic acid were added to the prepolymer, and the reaction was continued at 80°C for 6 hours. After the reaction was completed, 0.5 g of triethylamine was used to neutralize and form a salt, and 40 g of deionized water was added to emulsify and obtain an aqueous polyurethane emulsion. This emulsion was coated onto the surface of the substrate fabric and cured at 80°C for 24 hours to obtain an asymmetric comb-like aqueous polyurethane protective coating with a thickness of 200 μm ± 1 μm.

[0070] Experimental Example 1

[0071] The performance of the asymmetric comb-shaped waterborne polyurethane protective coating and the coated fabric prepared in Examples 1-4 was tested, as follows:

[0072] (1) Fourier transform infrared spectroscopy and nuclear magnetic resonance hydrogen spectroscopy analysis

[0073] The asymmetric comb-shaped waterborne polyurethane protective coating prepared in Example 2 was used for testing. Figure 1 The infrared spectrum (A) and proton nuclear magnetic resonance spectrum (B) of the polyurethane protective coating show that the characteristic peaks and characteristic signals in the figure correspond one-to-one with the theoretical values, confirming the successful synthesis of polyurethane.

[0074] (2) Scanning electron microscopy and elemental energy dispersive spectroscopy

[0075] Figure 2 The surface morphology and elemental distribution of the coated fabric prepared in Example 2 are shown in the scanning electron microscope (A) and X-ray energy dispersive spectroscopy (XEDS). As can be seen from the figure, the coating is well bonded to the fabric substrate, and the main elements in the coating are uniformly distributed on the fabric surface.

[0076] (3) Contact angle test and interfacial surface energy calculation

[0077] like Figure 3As shown, the contact angles of water and diiodomethane prepared in Example 2 were recorded as 123.2° and 93.6°, respectively. The coating has a low surface energy of 12.44 mJ / m² and good hydrophobic properties.

[0078] (4) Stain resistance test of coated fabric

[0079] like Figure 4 As shown, stain resistance tests were conducted on the coated fabric prepared in Example 2 using three contaminants: sauce, red wine, and cola. Compared to the original fabric, stains applied to the coated fabric remained spherical and could be easily wiped away. Liquid contaminants could not diffuse into the surface coating, and any traces left could be easily removed without leaving a mark.

[0080] (5) Test of acid and alkali resistance of coated fabrics

[0081] like Figure 5 As shown, the coated fabrics prepared in Example 2 were subjected to acid and alkali corrosion resistance tests using acidic and alkaline solutions (pH=2 and 13) prepared with sulfuric acid and hydrochloric acid. To simulate an acid-alkali corrosion environment, aqueous solutions of 0.5% sodium hydroxide and 0.1% sulfuric acid were applied to the coated wool and coated polyester fabrics, respectively. The changes in surface morphology of the fabrics after acid and alkali application at 0, 30, 60, and 90 minutes and after complete drying were observed using an optical microscope to evaluate the chemical corrosion resistance of the coating. Compared with the original fabric, the coating not only effectively protected the fabric but also exhibited significant chemical stability, leaving very small etching marks.

[0082] (6) Adsorption performance test of coated fabric

[0083] like Figure 6 As shown, the adsorption performance of the asymmetric comb-shaped aqueous polyurethane protective coating fabrics prepared in Examples 1-4 was tested using four gaseous organic pollutants: ammonia, acetic acid, formaldehyde, and limonene. The adsorption performance of the polyethylene-coated fabrics for these four volatile organic compounds was tested in a closed environment at 25 °C. The adsorption capacity was calculated using the following formula: Where Q represents the adsorption capacity of the coated fabric, M0 is the original mass of the coated fabric (g), and M1 is the mass of the coated fabric (g) after 12 hours of adsorption.

[0084] The coated fabrics prepared in Examples 1-4 all exhibited good adsorption effects on four types of gaseous organic pollutants. Specifically, at 2 mg / m³... 3 In a formaldehyde-rich environment, the coated fabric achieves a formaldehyde removal rate of over 90%.

[0085] (7) Coating self-healing performance test

[0086] like Figure 7 As shown, the self-healing performance of the asymmetric comb-shaped waterborne polyurethane protective coatings prepared in Comparative Examples 1, 2, and 2 after scratch and cut damage was tested. (A), (B), and (C) represent Examples 2, 1, and 2, respectively. Cutting and fracture damage to the polyurethane coating film (50 mm × 20 mm × 5 mm) was simulated using a blade, and the repair conditions were examined under an optical microscope at a repair temperature of 30 °C. The protective coating prepared in Example 2 repaired the scratch within only 10 minutes at 30 °C. When the damage escalated to a cut, the polyurethane coating successfully healed within 60 minutes, leaving only a surface healing mark.

[0087] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating, characterized in that, By weight, the following steps are included: Step 1: Mix 6-18 parts of polyethylene glycol, 7-21 parts of isophorone diisocyanate and 10-30 parts of N,N-dimethylformamide, and react at 75°C for 2-6 hours under a nitrogen atmosphere to obtain a prepolymer; Step 2: Add 5-15 parts of fluorinated monomer chain extender, 0.5-3 parts of 2-hydroxyethyl disulfide, 0.5-3 parts of 2-methyl-2-acrylate-2,3-dihydroxypropyl ester and 0.5-3 parts of 2,2-dimethylolpropionic acid to the above prepolymer, and continue the reaction at 80°C for 6-18 hours to obtain reaction solution A; Step 3: Add 0.5-6 parts of aminoβ-cyclodextrin to reaction solution A and continue the reaction at 70°C for 3-9 hours. After the reaction is completed, triethylamine is neutralized to form a salt, deionized water is added, and emulsification is performed to obtain a waterborne polyurethane emulsion. After coating on the substrate surface and curing, an asymmetric comb-shaped waterborne polyurethane protective coating is obtained.

2. The method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating according to claim 1, characterized in that, In step one, the molecular weight of polyethylene glycol is 600.

3. The method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating according to claim 1, characterized in that, The fluorinated monomer chain extender in step two is dihydroxy-modified tridecylfluorooctyl methacrylate, which is prepared as follows: by weight, 4-12 parts of tridecylfluorooctyl methacrylate and 3-9 parts of thioglycerol are dissolved in 10-30 parts of dichloromethane and 0.01-0.05 parts of photoinitiator. After thorough mixing, the mixture is reacted under ultraviolet light at 365 nm at room temperature for 4-8 hours. After rotary evaporation, it is dissolved in water, extracted with dichloromethane, and dried to obtain an oily liquid fluorinated long-chain chain extender.

4. The method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating according to claim 3, characterized in that, The photoinitiator is benzoin dimethyl ether.

5. The method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating according to claim 1, characterized in that, In step three, the amino-β-cyclodextrin is a monoamino-modified β-cyclodextrin, and its preparation method is as follows: By weight, 50-150 parts of β-CD and 15-45 parts of 4-toluenesulfonyl chloride are reacted at room temperature under alkaline conditions for 24 hours with water as the solvent. The filtrate is collected by static filtration, the pH is adjusted to 8 with ammonium chloride, and the mixture is cooled and crystallized at 4°C. After filtration and drying, mono-6-oxo-(p-toluenesulfonyl)-β-cyclodextrin powder is obtained. 5-15 parts of the above product are taken and treated with 50-150 parts of 28% ammonia water at 75°C. After cooling, acetone is precipitated and the mixture is filtered to obtain white powder 6-amino-6-deoxy-β-cyclodextrin.

6. The method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating according to claim 1, characterized in that, The curing conditions in step three are: curing temperature of 40-80℃ and curing time of 12-48 hours.

7. The method for preparing an asymmetric comb-shaped waterborne polyurethane protective coating according to claim 1, characterized in that, In step three, the thickness of the asymmetric comb-shaped waterborne polyurethane protective coating is 1-200 μm.

8. An asymmetric comb-shaped waterborne polyurethane protective coating prepared according to the method of claim 1.

9. The application of the asymmetric comb-shaped waterborne polyurethane protective coating according to claim 8 in the preparation of anti-corrosion fabrics.

10. The application of an asymmetric comb-shaped waterborne polyurethane protective coating as described in claim 8 as a protective coating against toxic and harmful gases.

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