High-durability super-hydrophobic coating as well as preparation method, stripping method and application thereof

Abstract

The invention belongs to the technical field of recycling of waste textiles, and provides a high-durability super-hydrophobic coating as well as a preparation method, a stripping method and application thereof. The preparation method of the high-durability super-hydrophobic coating comprises the following steps: alternately depositing a cationic substance and an anionic substance on the surface of a fabric, and controlling the number of assembly layers to obtain an assembled fabric; the assembled fabric is soaked in a tanning agent solution to be tanned, and tanned fabric is obtained; the tanned fabric is soaked in an octadecylamine solution for a thermocuring reaction, and the fabric with the high-durability super-hydrophobic coating is obtained. According to the prepared high-durability super-hydrophobic coating, 100% of biological derived components are used, use of organic solvents is avoided, and micro-plastic risks and toxic emission are eliminated.

Description

Technical Field

[0001] The present invention relates to the technical field of recycling waste textiles, and in particular to a highly durable super-hydrophobic coating, a preparation method thereof, a stripping method thereof, and an application thereof. Background Art

[0002] The widespread use of functional coatings has exacerbated the problem of low fabric recycling efficiency, especially water-repellents, which form a permanent three-dimensional cross-linked network on the fabric surface after being cured by a cross-linking agent, thereby ensuring mechanical properties and washability. These coatings have basic properties such as water repellency, self-cleaning, antibacterial adhesion and anti-icing ability. Due to the non-melting and insoluble characteristics of the coating, it is difficult to peel the coating from the fabric surface. If forcibly peeled off, it will cause damage to the fabric fibers, making the fabric unable to be recycled. Therefore, the choice of recycling method is relatively strict. Among them, mechanical stripping has the risk of damaging the fibers, while chemical stripping relies on strong polar solvents, acids or alkalis, which will cause the risk of secondary pollution. Nevertheless, the easy stripping of the coating does not mean weak interfacial bonding or poor durability. Therefore, it is of great significance to develop a coating that balances high durability during use and environmentally friendly stripping on demand at the end of the life cycle to ensure sustainable textile circularity.

[0003] In this regard, covalent adaptive networks (CANs) have become a revolutionary approach to overcome this challenge. Their dynamic bonds (such as imines, disulfides, and β-hydroxy esters) can maintain the integrity of the network during use, but will dissociate under mild conditions due to stimulation. This achieves two key functions: self-repair and reprocessing performance through dynamic bond reorganization, and on-demand degradation through dynamic bond dissociation (such as acid-catalyzed hydrolysis of imine bonds; cleavage of disulfide bonds by reducing agents; base-catalyzed hydrolysis of β-hydroxy esters). This dual ability can ensure ecological compatibility while maintaining the durability of the coating, making CANs the key to the recycling of coated textiles.

[0004] Furthermore, the contradiction between superhydrophobic coatings and the environment further exacerbates the complexity of recycling. Its layered structure consists of air-filled void structures, which reduce the surface contact area of ​​the droplets while enhancing their hydrophobic properties. However, the preparation process usually involves the use of fluorinated chemicals and organic solvents, which leads to the accumulation of biological toxicity and the risk of non-degradability. In addition, the surface protrusions are easily worn, resulting in a decrease in superhydrophobicity. The mechanical properties of the coating can be improved by doping with inorganic or organic nanoparticles (NPs), such as SiO2, TiO2 and PTFE. However, even water-based coatings may release microplastics or micro / nanoparticles into water and soil, and are difficult to separate from the water phase.

[0005] Therefore, it is of great significance to study a highly durable superhydrophobic coating with excellent water washing and friction durability, easy stripping, environmental friendliness and little damage to fibers, as well as its preparation method, stripping method and application. Summary of the Invention

[0006] The purpose of the present invention is to provide a highly durable super-hydrophobic coating and its preparation method, stripping method and application, so as to solve the problems of easy wear, difficult stripping and strong fiber damage caused by stripping in the prior art.

[0007] In order to achieve the above-mentioned object of the invention, the present invention provides the following technical solutions:

[0008] The present invention provides a method for preparing a highly durable super-hydrophobic coating, comprising the following steps:

[0009] 1) alternately depositing cationic substances and anionic substances on the surface of the fabric, controlling the number of assembled layers, and obtaining an assembled fabric;

[0010] 2) soaking the assembled fabric in a tanning agent solution for tanning to obtain a tanned fabric;

[0011] 3) soaking the tanned fabric in an octadecylamine solution to perform a thermal curing reaction to obtain a fabric with a highly durable superhydrophobic coating.

[0012] Preferably, in step 1), when depositing the cationic substance, the cationic deposition reagent comprises the cationic substance, acid and water;

[0013] In the cationic deposition reagent, the cationic substance is chitosan and / or polyethyleneimine, the concentration of the cationic substance is 10 to 20 g / L, and the amount of acid added is such that the pH value of the cationic deposition reagent is 2 to 4;

[0014] When depositing anionic species, the anionic deposition reagent includes anionic species, base and water;

[0015] In the anionic deposition reagent, the anionic substance is one or more of collagen, sodium polyphosphate and sodium alginate, the concentration of the anionic substance is 10-50 g / L, and the amount of alkali added is such that the pH value of the anionic deposition reagent is 10-12.

[0016] Preferably, in step 1), the deposition time of the cationic substance and the anionic substance is independently 2 to 10 minutes each time;

[0017] The acid is one or more of acetic acid, hydrochloric acid and sulfuric acid, and the concentration of the acid is 0.8 to 1.2 mol / L;

[0018] The alkali is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 0.8 to 1.2 mol / L;

[0019] A layer of cationic material and a layer of anionic material constitute one layer, and the number of assembled layers is 5 to 20 layers.

[0020] Preferably, in step 2), the tanning agent solution comprises a tanning agent, hydrochloric acid and water;

[0021] The tanning agent is one or more of tannic acid, genipin, glutaraldehyde, vanillin and aldehyded cellulose nanocrystals;

[0022] In the tanning agent solution, the concentration of the tanning agent is 1-10 g / L, the concentration of the hydrochloric acid is 0.8-1.2 mol / L, and the amount of hydrochloric acid added is such that the pH value of the tanning agent solution is 4-5.

[0023] Preferably, in step 2), the tanning temperature is 40 to 80° C., and the tanning time is 24 to 48 hours.

[0024] Preferably, in step 3), the solvent of the octadecylamine solution is anhydrous ethanol, and the concentration of octadecylamine in the octadecylamine solution is 1 to 5 wt%;

[0025] The temperature of the thermal curing reaction is 25 to 60° C., and the time of the thermal curing reaction is 1 to 4 hours.

[0026] The present invention also provides a highly durable super-hydrophobic coating prepared by the method for preparing the highly durable super-hydrophobic coating.

[0027] The present invention also provides a method for stripping a highly durable super-hydrophobic coating, comprising the following steps: wetting the fabric having the highly durable super-hydrophobic coating with ethanol, placing the fabric in an acidic solution for dissociation, and after the dissociation is completed, removing the fabric and scrubbing the fabric to complete the stripping of the highly durable super-hydrophobic coating.

[0028] Preferably, in the acidic solution, the solute includes one or more of acetic acid, hydrochloric acid and nitric acid, the solvent is water, and the concentration of the acidic solution is 2.5 to 10 wt%;

[0029] The dissociation temperature is 60-80°C, and the dissociation time is 0.5-8h.

[0030] The present invention also provides application of the highly durable super-hydrophobic coating in the field of fabric waterproofing.

[0031] It can be seen from the above technical solutions that compared with the prior art, the present invention has the following beneficial effects:

[0032] The highly durable super-hydrophobic coating of the present invention can be peeled off by pre-wetting the fabric with ethanol, soaking it in an acidic solution for dissociation, and then scrubbing it with a continuous water flow, due to the acid-triggered dissociation performance of the dynamic imine bond, with minimal damage to the fiber.

[0033] The high durable super-hydrophobic coating prepared by the present invention uses 100% biologically derived components (cationic substances, anionic substances, tannic acid, octadecylamine), avoids the use of organic solvents, eliminates microplastic risk and toxic discharge. By regulating the number of plies of cationic substances and anionic substances assembly, the hardness and the pliability of the super-hydrophobic coating can be regulated and controlled, and the covalent adaptability network formed by the cross-linking of tanning agents mediation enhances the wash resistance of the super-hydrophobic coating. In addition, the dissociation of the imine bond of acid triggering promotes the degraded covalent adaptability network and the coating is peeled off from the fabric surface, and the stripping condition is gentle and pollution-free, and the damage to fiber is less. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are merely embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the provided drawings without paying any creative work.

[0035] Figure 1 Schematic diagram of the preparation route of the cotton fabric with a highly durable superhydrophobic coating in Example 1;

[0036] Figure 2 This is a photograph of the contact angle of diiodomethane on the surface of the cotton fabric with a highly durable superhydrophobic coating obtained in Example 1;

[0037] Figure 3 The weight gain rate and pencil hardness test results of cotton fabrics with high-durable superhydrophobic coatings with different numbers of assembled layers are shown in Figure 1; wherein, a is the weight gain rate test result graph, and b is the pencil hardness test result graph;

[0038] Figure 4 These are SEM images of the cotton fabric, assembled cotton fabric, tanned cotton fabric, and cotton fabric with a highly durable superhydrophobic coating in Example 1; wherein a is cotton fabric, b is assembled cotton fabric, c is tanned cotton fabric, and d is cotton fabric with a highly durable superhydrophobic coating;

[0039] Figure 5 Graphs showing the waterproof performance of cotton fabrics with a highly durable superhydrophobic coating obtained in Example 1, where a (top) shows an optical image of spherical liquids (water, coffee, and milk) placed on cotton fabric, a (bottom) shows an optical image of spherical liquids (water, coffee, and milk) placed on cotton fabrics with a highly durable superhydrophobic coating, and b shows the silver mirror effect of superhydrophobic fabrics.

[0040] Figure 6Surface self-cleaning performance diagram of the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1; wherein a is cotton fabric, b is assembled cotton fabric, c is tanned cotton fabric, and d is cotton fabric with a highly durable super-hydrophobic coating;

[0041] Figure 7 Schematic diagram of the cross-linking system during the tanning process in Example 1;

[0042] Figure 8 Schematic diagram of the cross-linking system after the thermal curing reaction in Example 1;

[0043] Figure 9 The figure is a diagram showing the washing durability test results of the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1; wherein, a is a diagram showing the washing durability test results, and b is a SEM image of the cotton fabric after 20 cycles of the washing durability test.

[0044] Figure 10 Figure 1 is a graph showing the friction durability test results of the cotton fabric with a highly durable superhydrophobic coating obtained in Example 1; wherein, Figure c is a graph showing the friction durability test results, and Figure d is a SEM image of the cotton fabric after 1000 cycles of the friction durability test;

[0045] Figure 11 This is a graph showing the chemical stability of the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1;

[0046] Figure 12 Schematic diagram of the coating stripping mechanism of the cotton fabric with a highly durable superhydrophobic coating obtained in Example 1;

[0047] Figure 13 This is an SEM image of the cotton fabric with a highly durable superhydrophobic coating obtained in Example 1 after the coating is peeled off. DETAILED DESCRIPTION

[0048] The present invention provides a method for preparing a highly durable super-hydrophobic coating, comprising the following steps:

[0049] 1) alternately depositing cationic substances and anionic substances on the surface of the fabric, controlling the number of assembled layers, and obtaining an assembled fabric;

[0050] 2) soaking the assembled fabric in a tanning agent solution for tanning to obtain a tanned fabric;

[0051] 3) soaking the tanned fabric in an octadecylamine solution to perform a thermal curing reaction to obtain a fabric with a highly durable superhydrophobic coating.

[0052] The method for preparing the highly durable super-hydrophobic coating of the present invention adopts layer-by-layer self-assembly, so that the cationic material layer and the anionic material layer are bonded by electrostatic adsorption;

[0053] During the tanning stage, when the tanning agent is tannic acid (TA), since the pKa value of TA is 5, when the pH value of the solution is higher than 4, the phenolic hydroxyl groups of TA are ionized, making the tanning agent solution negatively charged. Under this condition, cationic and anionic substances are protonated, and the fixation of tannic acid is increased through ionic bonds.

[0054] After grafting octadecylamine, the phenolic hydroxyl group of TA is oxidized to a quinone intermediate structure through thermal curing reaction, which undergoes Schiff base reaction and 1,4-Michael addition reaction with the amino groups on cationic and anionic substances. The electrostatic adsorption between the cationic and anionic substance layers is transformed into imine bonds and CN bonds, forming a covalent adaptive network.

[0055] In the present invention, in step 1), when depositing the cationic substance, the cationic deposition reagent preferably includes the cationic substance, acid and water;

[0056] In the cationic deposition agent, the cationic substance is preferably chitosan and / or polyethyleneimine, the concentration of the cationic substance is preferably 10 to 20 g / L, more preferably 12 to 18 g / L, more preferably 14 to 16 g / L, and the amount of acid added is preferably such that the pH value of the cationic deposition agent is 2 to 4, more preferably 2.5 to 3.5, more preferably 3 to 3.2;

[0057] When depositing anionic species, the anionic deposition reagent preferably comprises anionic species, a base, and water;

[0058] In the anionic deposition reagent, the anionic substance is one or more of collagen, sodium polyphosphate and sodium alginate. The concentration of the anionic substance is preferably 10 to 50 g / L, more preferably 20 to 40 g / L, and more preferably 25 to 30 g / L. The amount of base added is preferably such that the pH value of the anionic deposition reagent is 10 to 12, more preferably 10.5 to 11.5, and more preferably 10.8 to 11.

[0059] In the present invention, in step 1), the deposition time of the cationic substance and the anionic substance is preferably 2 to 10 minutes, more preferably 4 to 8 minutes, and more preferably 5 to 6 minutes.

[0060] The acid is preferably one or more of acetic acid, hydrochloric acid and sulfuric acid, and the concentration of the acid is preferably 0.8 to 1.2 mol / L, more preferably 0.9 to 1.1 mol / L, and more preferably 1 mol / L;

[0061] The alkali is preferably a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is preferably 0.8 to 1.2 mol / L, more preferably 0.9 to 1.1 mol / L, and more preferably 1 mol / L;

[0062] With one layer of cationic substance and one layer of anionic substance forming one layer, the number of assembled layers is preferably 5 to 20 layers, more preferably 8 to 16 layers, and even more preferably 10 to 12 layers.

[0063] In the present invention, in the step 1), the cationic substance and the anionic substance are sequentially rolled and baked after deposition;

[0064] The purpose of the rolling is to remove excess solution;

[0065] The baking temperature is independently preferably 160-200° C., more preferably 170-190° C., more preferably 180-185° C., and the baking time is independently preferably 50-70 seconds, more preferably 55-65 seconds, more preferably 60-62 seconds.

[0066] In the present invention, in step 2), the tanning agent solution preferably comprises a tanning agent, hydrochloric acid and water;

[0067] The tanning agent is preferably one or more of tannic acid, genipin, glutaraldehyde, vanillin and aldehyded cellulose nanocrystals;

[0068] In the tanning agent solution, the concentration of the tanning agent is preferably 1 to 10 g / L, more preferably 3 to 8 g / L, more preferably 4 to 6 g / L, the concentration of the hydrochloric acid is preferably 0.8 to 1.2 mol / L, more preferably 0.9 to 1.1 mol / L, more preferably 1 mol / L, and the amount of hydrochloric acid added is preferably such that the pH value of the tanning agent solution is 4 to 5, more preferably 4.2 to 4.8, more preferably 4.4 to 4.6.

[0069] In the present invention, in step 2), the tanning temperature is preferably 40-80°C, more preferably 50-70°C, more preferably 60-65°C, and the tanning time is preferably 24-48h, more preferably 28-40h, more preferably 32-38h.

[0070] In the present invention, in the step 2), drying is performed after tanning; the drying temperature is preferably 80-100°C, more preferably 85-95°C, more preferably 88-90°C, and the drying time is preferably 50-70 min, more preferably 55-65 min, more preferably 60 min.

[0071] In the present invention, in step 3), the solvent of the octadecylamine solution is preferably anhydrous ethanol, and the concentration of octadecylamine in the octadecylamine solution is preferably 1 to 5 wt%, more preferably 2 to 4 wt%, and more preferably 3 wt%;

[0072] The temperature of the thermal curing reaction is preferably 25 to 60° C., more preferably 30 to 50° C., and more preferably 40 to 45° C. The time of the thermal curing reaction is preferably 1 to 4 hours, more preferably 2 to 3.5 hours, and more preferably 2.5 to 3 hours.

[0073] In the present invention, in step 3), drying is performed after the thermal curing reaction; the drying temperature is preferably 80-100°C, more preferably 85-95°C, more preferably 88-90°C, and the drying time is preferably 50-70 min, more preferably 55-65 min, more preferably 60 min.

[0074] The present invention also provides a highly durable super-hydrophobic coating prepared by the method for preparing the highly durable super-hydrophobic coating.

[0075] The present invention also provides a method for stripping a highly durable super-hydrophobic coating, comprising the following steps: wetting the fabric having the highly durable super-hydrophobic coating with ethanol, placing the fabric in an acidic solution for dissociation, and after the dissociation is completed, removing the fabric and scrubbing the fabric to complete the stripping of the highly durable super-hydrophobic coating.

[0076] In the present invention, the solute in the acidic solution preferably includes one or more of acetic acid, hydrochloric acid and nitric acid, the solvent is preferably water, and the concentration of the acidic solution is preferably 2.5 to 10 wt%, more preferably 4 to 8 wt%, and more preferably 5 to 6 wt%;

[0077] The dissociation temperature is preferably 60-80°C, more preferably 65-75°C, more preferably 70-72°C, and the dissociation time is preferably 0.5-8h, more preferably 2-7h, more preferably 4-5h; the ethanol is preferably anhydrous ethanol; the scrubbing is preferably scrubbing under water flow, and the scrubbing time is preferably 8-12min, more preferably 9-11min, more preferably 10min.

[0078] The present invention also provides application of the highly durable super-hydrophobic coating in the field of fabric waterproofing.

[0079] The technical solutions provided by the present invention are described in detail below with reference to the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0080] Example 1

[0081] Chitosan, 1 mol / L acetic acid and water were mixed to obtain a chitosan deposition reagent having a chitosan concentration of 20 g / L and a pH of 3;

[0082] Collagen (molecular weight of approximately 300 kD), 1 mol / L sodium hydroxide aqueous solution, and water were mixed to obtain a collagen deposition reagent having a collagen concentration of 30 g / L and a pH of 10;

[0083] Mixing tannic acid, 1 mol / L hydrochloric acid and water to obtain a tanning agent solution having a tannic acid concentration of 1 g / L and a pH of 4;

[0084] Mixing octadecylamine and anhydrous ethanol to obtain an octadecylamine solution having an octadecylamine concentration of 1 wt %;

[0085] The cotton fabric was placed in a chitosan deposition reagent for 5 minutes, then taken out, rolled with a roller to remove excess solution, and then baked at 180°C for 1 minute to complete the deposition of a layer of chitosan; the cotton fabric with chitosan deposited was placed in a collagen deposition reagent for 5 minutes, then taken out, rolled with a roller to remove excess solution, and then baked at 180°C for 1 minute to complete the deposition of a layer of collagen; one layer of chitosan and one layer of collagen were counted as one layer, and after assembling 12 layers, an assembled cotton fabric was obtained;

[0086] The assembled cotton fabric was placed in a tanning agent solution and tanned at 80°C for 24 hours, and then dried at 90°C for 1 hour to obtain a tanned cotton fabric;

[0087] The tanned cotton fabric was placed in an octadecylamine solution for a thermal curing reaction at 60°C for 2 hours, and then dried at 90°C for 1 hour to obtain a cotton fabric with a highly durable superhydrophobic coating.

[0088] Example 2

[0089] Mixing polyethyleneimine, 1 mol / L acetic acid, and water to obtain a polyethyleneimine deposition reagent having a polyethyleneimine concentration of 30 g / L and a pH of 2;

[0090] Mixing collagen, a 1 mol / L sodium hydroxide aqueous solution, and water to obtain a collagen deposition reagent having a collagen concentration of 50 g / L and a pH of 12;

[0091] Genipin, 1 mol / L hydrochloric acid and water were mixed to obtain a tanning agent solution having a genipin concentration of 1 g / L and a pH of 4;

[0092] Mixing octadecylamine and anhydrous ethanol to obtain an octadecylamine solution having an octadecylamine concentration of 1 wt %;

[0093] The cotton fabric was placed in a polyethyleneimine deposition reagent for deposition for 5 minutes, then taken out, rolled with a roller to remove excess solution, and then baked at 180°C for 1 minute to complete the deposition of a layer of polyethyleneimine; the cotton fabric with polyethyleneimine deposited was placed in a collagen deposition reagent for deposition for 5 minutes, then taken out, rolled with a roller to remove excess solution, and then baked at 180°C for 1 minute to complete the deposition of a layer of collagen; a layer of polyethyleneimine and a layer of collagen were counted as one layer, and after assembling 12 layers, an assembled cotton fabric was obtained;

[0094] The assembled cotton fabric was placed in a tanning agent solution and tanned at 80°C for 24 hours, and then dried at 90°C for 1 hour to obtain a tanned cotton fabric;

[0095] The tanned cotton fabric was placed in an octadecylamine solution for a thermal curing reaction at 60°C for 2 hours, and then dried at 90°C for 1 hour to obtain a cotton fabric with a highly durable superhydrophobic coating.

[0096] Example 3

[0097] Chitosan, 1 mol / L acetic acid and water were mixed to obtain a chitosan deposition reagent having a chitosan concentration of 20 g / L and a pH of 3;

[0098] Mixing sodium polyphosphate, a 1 mol / L sodium hydroxide aqueous solution, and water to obtain a sodium polyphosphate precipitation reagent having a sodium polyphosphate concentration of 30 g / L and a pH value of 10;

[0099] Glutaraldehyde, 1 mol / L hydrochloric acid and water were mixed to obtain a tanning agent solution having a glutaraldehyde concentration of 1 g / L and a pH of 4;

[0100] Mixing octadecylamine and anhydrous ethanol to obtain an octadecylamine solution having an octadecylamine concentration of 1 wt %;

[0101] The cotton fabric was placed in a chitosan deposition reagent for 5 minutes, then taken out, rolled with a roller to remove excess solution, and then baked at 180°C for 1 minute to complete the deposition of a layer of chitosan; the cotton fabric with chitosan deposited was placed in a sodium polyphosphate deposition reagent for 5 minutes, then taken out, rolled with a roller to remove excess solution, and then baked at 180°C for 1 minute to complete the deposition of a layer of sodium polyphosphate; a layer of chitosan and a layer of sodium polyphosphate were counted as one layer, and after assembling 12 layers, an assembled cotton fabric was obtained;

[0102] The assembled cotton fabric was placed in a tanning agent solution and tanned at 80°C for 24 hours, and then dried at 90°C for 1 hour to obtain a tanned cotton fabric;

[0103] The tanned cotton fabric was placed in an octadecylamine solution for a thermal curing reaction at 60°C for 2 hours, and then dried at 90°C for 1 hour to obtain a cotton fabric with a highly durable superhydrophobic coating.

[0104] Example 4

[0105] Chitosan, 1 mol / L acetic acid and water were mixed to obtain a chitosan deposition reagent having a chitosan concentration of 20 g / L and a pH of 3;

[0106] Mixing sodium alginate, a 1 mol / L sodium hydroxide aqueous solution, and water to obtain a sodium alginate deposition reagent having a sodium alginate concentration of 30 g / L and a pH of 10;

[0107] mixing aldehyde-modified cellulose nanocrystals, 1 mol / L hydrochloric acid, and water to obtain a tanning agent solution having a aldehyde-modified cellulose nanocrystal concentration of 1 g / L and a pH of 4;

[0108] Mixing octadecylamine and anhydrous ethanol to obtain an octadecylamine solution having an octadecylamine concentration of 1 wt %;

[0109] The cotton fabric was placed in a chitosan deposition reagent for 5 minutes, then taken out, rolled with a roller to remove excess solution, and then baked at 180°C for 1 minute to complete the deposition of a layer of chitosan; the cotton fabric with chitosan deposited was placed in a sodium alginate deposition reagent for 5 minutes, then taken out, rolled with a roller to remove excess solution, and then baked at 180°C for 1 minute to complete the deposition of a layer of sodium alginate; a layer of chitosan and a layer of sodium alginate were counted as one layer, and after assembling 12 layers, an assembled cotton fabric was obtained;

[0110] The assembled cotton fabric was placed in a tanning agent solution and tanned at 80°C for 24 hours, and then dried at 90°C for 1 hour to obtain a tanned cotton fabric;

[0111] The tanned cotton fabric was placed in an octadecylamine solution for a thermal curing reaction at 60°C for 2 hours, and then dried at 90°C for 1 hour to obtain a cotton fabric with a highly durable superhydrophobic coating.

[0112] The following performance tests were performed on the cotton fabrics with highly durable super-hydrophobic coatings obtained in Examples 1 to 4:

[0113] (1) Surface energy test

[0114] The contact angle of the super-hydrophobic fabric was measured by a contact angle meter using diiodomethane as the test liquid. Figure 2 shown.

[0115] The contact angle of diiodomethane on the cotton fabric surface with a highly durable super-hydrophobic coating obtained in Example 1 is shown in the following figure: Figure 2 As shown. Figure 2 It can be seen that the water contact angle of the known super-hydrophobic cotton fabric is as high as 158.6°, and the diiodomethane contact angle is 91°. After calculation, the surface energy of the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1 is as low as 23.8 mN / m. Figure 6 The surface self-cleaning performance of the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1 is shown in the figure. It can be seen that the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1 conforms to the Cassie-type super-hydrophobic model.

[0116] (2) Weight gain and pencil hardness test

[0117] According to the preparation method of the cotton fabric with a highly durable super-hydrophobic coating as described in Example 1, the cotton fabric with a highly durable super-hydrophobic coating was weighed and tested for hardness by a pencil when the number of assembled layers was 2, 4, 6, 8, and 10, and the weighing and test results were as follows: Figure 3 shown.

[0118] The weight gain and pencil hardness test results of cotton fabrics with high-durability superhydrophobic coatings with different assembly layers are shown in the figure. Figure 3 As shown, a is the weight gain test result diagram, b is the pencil hardness test result diagram, Figure 3 It can be seen that as the number of assembled layers increases, the coating weight gain rate and hardness continue to increase, and only a 10% weight increase can make the coating hardness as high as 8H.

[0119] (3) Electron microscopy test

[0120] The surface morphologies of the cotton fabric, assembled cotton fabric, tanned cotton fabric and cotton fabric with a highly durable superhydrophobic coating in Example 1 were observed using a TM4000II scanning electron microscope. Figure 4 shown.

[0121] The SEM images of the cotton fabric, assembled cotton fabric, tanned cotton fabric and cotton fabric with highly durable superhydrophobic coating in Example 1 are as follows: Figure 4 As shown; wherein, a is a SEM image of cotton fabric, b is a SEM image of assembled cotton fabric, c is a SEM image of tanned cotton fabric, and d is a SEM image of cotton fabric with a highly durable superhydrophobic coating. Figure 4 It can be seen that the cotton fabric has a smooth surface, an irregular waist-shaped circular cross-section and spiral twists along the length of the fiber; the assembled cotton fabric is densified by roller extrusion, the porosity of the fabric is reduced, and the coating can be seen wrapping the fiber; in the tanned cotton fabric, fine particles are embedded in the fiber due to the complex formed by ionic bonding between tannic acid and chitosan / collagen; after grafting octadecylamine, a large amount of colloidal substances appear on the fiber.

[0122] (4) Water washing durability and friction durability test

[0123] Washing durability: tested according to AATCC 61-2006 No.2A test method, the test results are as follows Figure 9 As shown in (a) and (b);

[0124] Friction durability: A load of 100 g was placed on the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1, and then the fabric was pulled along a 1500 grit sandpaper for 20 cm. The WCA test was then performed. The test results are shown in the figure. Figure 10 As shown in (c) and (d).

[0125] The washing durability test results of the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1 are shown in FIG. Figure 9 As shown; wherein, a is a water washing durability test result diagram, b is a SEM image of the cotton fabric after the water washing durability test; the friction durability test result diagram of the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1 is as shown Figure 10 As shown; wherein, c is the friction durability test result diagram, d is the SEM diagram of the cotton fabric after the friction durability test. Figure 9 and Figure 10 It can be seen that the cotton fabric with a highly durable superhydrophobic coating prepared in Example 1 exhibits excellent washing durability and friction durability, and the superhydrophobic properties of the surface are maintained even after undergoing 20 cycles of AATCC accelerated water washing (equivalent to 100 cycles of household conventional washing) and 1000 cycles of sandpaper friction.

[0126] (5) Chemical stability test

[0127] Take two pieces of cotton fabrics with high durable super hydrophobic coating obtained in Example 1 of the same specification, soak them in hydrochloric acid with a pH value of 3 and sodium hydroxide solution with a pH value of 11, respectively, and take them out when the soaking time is 0h, 4h, 8h, 12h, 16h, 20h and 24h, and perform WCA test. The test results are as follows: Figure 11 shown.

[0128] Chemical stability test of cotton fabric with highly durable super hydrophobic coating obtained in Example 1 Figure 11 As shown. Figure 11 It can be seen that when the cotton fabric with a highly durable superhydrophobic coating obtained in Example 1 is immersed in hydrochloric acid, the imine bond is more easily attacked by hydrogen ions and dissociated, resulting in a greater decrease in WCA than in an alkaline environment.

[0129] (6) Coating peeling performance

[0130] The cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1 was moistened with anhydrous ethanol, placed in an aqueous acetic acid solution with a concentration of 5 wt%, and stripped at 80°C for 2 h. After that, it was fished out and scrubbed under running water for 10 min to obtain the cotton fabric after the coating was stripped. The strength of the cotton fabric in Example 1, the cotton fabric with a highly durable super-hydrophobic coating, and the cotton fabric after the coating was stripped were tested, and the test results are shown in Table 1.

[0131] Table 1 Strength test results of cotton fabric with highly durable super-hydrophobic coating obtained in Example 1 before and after coating peeling

[0132]

[0133] As shown in Table 1, after the coating is stripped, the strength of the cotton fabric is only damaged by 12% compared with that of the cotton fabric. This damage is mainly attributed to the acid-catalyzed cleavage of the glycosidic bonds in the cellulose macromolecular chain.

[0134] The schematic diagram of the coating stripping mechanism of the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1 is as follows Figure 12 As shown. Figure 12 It can be seen that under the action of acid, the imine bond dissociates, and the interaction force between the chitosan and collagen layers returns to being mainly ionic bond. Under the action of scrubbing, the coating can be peeled off from the fabric surface.

[0135] The SEM image of the cotton fabric with a highly durable super-hydrophobic coating obtained in Example 1 after the coating is peeled off is as follows: Figure 13 As shown. Figure 13 It can be seen that the surface of the fabric is clean and tidy after the coating is stripped, indicating that the coating stripping efficiency is high.

[0136] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A method for preparing a highly durable super-hydrophobic coating, characterized in that: The steps include: 1) alternately depositing cationic substances and anionic substances on the surface of the fabric, controlling the number of assembled layers, and obtaining an assembled fabric; 2) soaking the assembled fabric in a tanning agent solution for tanning to obtain a tanned fabric; 3) soaking the tanned fabric in an octadecylamine solution to perform a thermal curing reaction to obtain a fabric with a highly durable superhydrophobic coating.

2. The method for preparing a highly durable super-hydrophobic coating according to claim 1, wherein In the step 1), when depositing the cationic substance, the cationic deposition reagent includes the cationic substance, acid and water; In the cationic deposition reagent, the cationic substance is chitosan and / or polyethyleneimine, the concentration of the cationic substance is 10 to 20 g / L, and the amount of acid added is such that the pH value of the cationic deposition reagent is 2 to 4; When depositing anionic species, the anionic deposition reagent includes anionic species, base and water; In the anionic deposition reagent, the anionic substance is one or more of collagen, sodium polyphosphate and sodium alginate, the concentration of the anionic substance is 10-50 g / L, and the amount of alkali added is such that the pH value of the anionic deposition reagent is 10-12.

3. A method for preparing a highly durable super-hydrophobic coating according to claim 2, wherein In the step 1), the deposition time of the cationic substance and the anionic substance is independently 2 to 10 minutes each time; The acid is one or more of acetic acid, hydrochloric acid and sulfuric acid, and the concentration of the acid is 0.8 to 1.2 mol / L; The alkali is a sodium hydroxide solution, and the concentration of the sodium hydroxide solution is 0.8 to 1.2 mol / L; A layer of cationic material and a layer of anionic material constitute one layer, and the number of assembled layers is 5 to 20 layers.

4. according to the preparation method of a kind of high durable super hydrophobic coating of claim 2 or 3, it is characterized in that, In the step 2), the tanning agent solution comprises a tanning agent, hydrochloric acid and water; The tanning agent is one or more of tannic acid, genipin, glutaraldehyde, vanillin and aldehyded cellulose nanocrystals; In the tanning agent solution, the concentration of the tanning agent is 1-10 g / L, the concentration of the hydrochloric acid is 0.8-1.2 mol / L, and the amount of hydrochloric acid added is such that the pH value of the tanning agent solution is 4-5.

5. A method for preparing a highly durable super-hydrophobic coating according to claim 4, characterized in that, In the step 2), the tanning temperature is 40 to 80° C., and the tanning time is 24 to 48 hours.

6. A method for preparing a highly durable super-hydrophobic coating according to claim 5, characterized in that, In the step 3), the solvent of the octadecylamine solution is anhydrous ethanol, and the concentration of octadecylamine in the octadecylamine solution is 1 to 5 wt%; The temperature of the thermal curing reaction is 25 to 60° C., and the time of the thermal curing reaction is 1 to 4 hours.

7. A highly durable super hydrophobic coating prepared by the method for preparing a highly durable super hydrophobic coating according to any one of claims 1 to 6.

8. A method for stripping a highly durable super-hydrophobic coating according to claim 7, characterized in that: The method comprises the following steps: wetting the fabric with the highly durable super-hydrophobic coating with ethanol, placing the fabric in an acidic solution for dissociation, and taking the fabric out and scrubbing the fabric after the dissociation is completed, thereby completing the stripping of the highly durable super-hydrophobic coating.

9. A method for stripping a highly durable super-hydrophobic coating according to claim 8, characterized in that: In the acidic solution, the solute includes one or more of acetic acid, hydrochloric acid and nitric acid, the solvent is water, and the concentration of the acidic solution is 2.5 to 10 wt%; The dissociation temperature is 60-80°C, and the dissociation time is 0.5-8h.

10. Use of the highly durable super-hydrophobic coating according to claim 7 in the field of fabric waterproofing.

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