Preparation method of fluoride-free super-hydrophobic nano silicon dioxide cotton fabric

Abstract

The invention discloses a preparation method of a fluorine-free super-hydrophobic nano silicon dioxide cotton fabric, and belongs to the technical field of super-hydrophobic textiles. According to the fluorine-free super-hydrophobic coating disclosed by the invention, silicon dioxide is modified and treated by utilizing trichloro octadecyl silane (OTS), gamma-glycidyl ether oxypropyl trimethoxy silane (KH-560) and hexadecyl trimethoxy silane (HDTMS), so that the fluorine-free super-hydrophobic coating is obtained. The coating is coated and finished on the surface of the cotton fabric, so that the finished cotton fabric has low surface energy and a rough surface structure and has an excellent super-hydrophobic effect, and meanwhile, the hydrophobic coating has certain durability and self-cleaning and antifouling capabilities.

Description

Technical Field

[0001] The invention belongs to the technical field of super-hydrophobic textiles, and particularly relates to a method for preparing fluorine-free super-hydrophobic nano-silica cotton fabric. Background Art

[0002] Cotton fabrics have the advantages of warmth, breathability, and easy dyeing and finishing. They are widely used in clothing, indoor supplies, medical treatment, and military. However, cotton fabrics are limited in application due to their shortcomings such as easy staining and easy wetting. Superhydrophobic surfaces can be widely used in the multifunctional finishing of cotton fabrics due to their special wettability. Silicon dioxide has the characteristics of low cost and simple and easy preparation, and has become an important raw material for establishing micro-nano structures and reducing surface tension. However, due to its poor adhesion to fabrics and poor durability, the application and service life of superhydrophobic fabrics are affected. Therefore, it is of great value to develop highly durable and highly hydrophobic coated cotton fabrics. Summary of the invention

[0003] In view of this, the purpose of the present invention is to provide a simple and environmentally friendly method for preparing fluorine-free super-hydrophobic nano-silica cotton fabric to solve the problem that the super-hydrophobic cotton fabric has a complicated preparation process or contains fluorine.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] The present invention provides a fluorine-free super-hydrophobic coating, wherein the fluorine-free super-hydrophobic coating is attached to a cotton fabric and comprises a hydrophobically modified silicon dioxide layer.

[0006] The hydrophobic silica in the hydrophobic silica layer is modifier-modified silica; the modifier includes trichlorooctadecylsilane (OTS), γ-glycidyloxypropyltrimethoxysilane (KH-560) and hexadecyltrimethoxysilane (HDTMS).

[0007] In one embodiment of the present invention, the particle size of the hydrophobically modified silica is 15 to 70 nm, more preferably 15 to 20 nm.

[0008] The present invention also provides a method for preparing the fluorine-free super-hydrophobic coating described in the above technical solution, comprising the following steps:

[0009] S1, mixing silica, a first modifier and an alcohol solvent to modify the silica to obtain hydrophobic silica;

[0010] S2, dispersing the second modifier in water to obtain a mixed solution;

[0011] S3, mixing the obtained hydrophobic silica, the mixed solution and the third modifier to obtain a fluorine-free super hydrophobic coating;

[0012] The first modifier, the second modifier and the third modifier are independently selected from trichlorooctadecylsilane, KH-560 and hexadecyltrimethoxysilane, respectively, and the second modifier and the third modifier are different.

[0013] In one embodiment of the present invention, it is further preferred that the first modifier, the second modifier, and the third modifier are different.

[0014] In one embodiment of the present invention, specifically, the first modifier is trichlorooctadecylsilane, the second modifier is KH-560, and the third modifier is hexadecyltrimethoxysilane.

[0015] In one embodiment of the present invention, specifically, the first modifier is hexadecyltrimethoxysilane, the second modifier is KH-560, and the third modifier is trichlorooctadecylsilane.

[0016] In one embodiment of the present invention, specifically, the first modifier is KH-560, the second modifier is trichlorooctadecylsilane, and the third modifier is hexadecyltrimethoxysilane.

[0017] In one embodiment of the present invention, the mass ratio of the first modifier, the second modifier, and the third modifier is (4-8):(3-5):1.

[0018] In one embodiment of the present invention, the particle size of the silicon dioxide in S1 is preferably 15 to 70 nm, and more preferably 15 nm to 20 nm.

[0019] In one embodiment of the present invention, the alcohol solvent in S1 is preferably ethanol.

[0020] In one embodiment of the present invention, the mass ratio of the silicon dioxide to the first modifier in S1 is 1:(10-20).

[0021] In one embodiment of the present invention, the usage ratio of the silicon dioxide and the alcohol solvent in S1 is preferably 1 g: (100-150 mL).

[0022] In one embodiment of the present invention, the mixing of silica, the first modifier and the alcohol solvent in S1 is preferably performed at room temperature, and the time is preferably 2 hours.

[0023] In one embodiment of the present invention, the concentration of the second modifier dispersed in water in S2 is 0.1-0.5 g / mL.

[0024] In one embodiment of the present invention, the dispersion temperature in S2 is preferably room temperature, and the dispersion time is preferably 0.5 h.

[0025] In one embodiment of the present invention, the temperature of the mixing and modification in S3 is 70-90° C. and the time is 3 hours.

[0026] The invention also provides a method for preparing fluorine-free super-hydrophobic nano-silica cotton fabric, which comprises coating the modified silica sol coating on the cotton fabric, and then drying and curing the coating to obtain the fluorine-free super-hydrophobic cotton fabric.

[0027] In one embodiment of the present invention, the curing temperature is preferably 90 to 150° C., more preferably 100 to 120° C.; the curing time is preferably 1 to 6 minutes, more preferably 2 to 3 minutes.

[0028] The present invention also provides the fluorine-free super-hydrophobic fabric described in the above technical solution.

[0029] The present invention also provides the application of the fluorine-free super-hydrophobic coating described in the above technical solution in the field of self-cleaning.

[0030] The present invention specifically provides a fluorine-free super-hydrophobic coating, the fluorine-free super-hydrophobic coating is arranged on a cotton fabric, and the fluorine-free super-hydrophobic coating includes a hydrophobic modified silica layer attached to the cotton fabric; the surface of the fluorine-free super-hydrophobic coating of the present invention is loaded with a layer of modified nano-silica particles arranged on the surface of the cotton fabric, so that the coating has both low surface energy and surface roughness structure; at the same time, the baking temperature in the preparation method is controlled to be 90-150°C, so that the hydrophobic coating has a certain durability. The use of modified silica makes the coating have super-hydrophobicity, and then has self-cleaning and anti-fouling capabilities.

[0031] The present invention also specifically provides a method for preparing the fluorine-free super-hydrophobic cotton fabric described in the above technical solution, comprising the following steps: silica, a modifier and an alcohol solvent are mixed, modified, and hydrophobic silica is obtained; KH-560 is hydrolyzed to obtain KH-560 sol; hydrophobic silica, KH-560 sol and hexadecyltrimethoxysilane are mixed and modified; the modified silica sol is applied on a substrate, pre-baked and baked, and the fluorine-free super-hydrophobic coating is obtained. The preparation method provided by the present invention is simple to operate and is easy to industrialize.

[0032] Furthermore, the curing temperature is controlled to be 90-150° C., so as to further improve the fastness of the fluorine-free super-hydrophobic coating and the cotton fabric.

[0033] Beneficial effects:

[0034] The contact angles of the fluorine-free super-hydrophobic coatings obtained by the present invention are all above 154.2°, and they exhibit excellent anti-fouling properties for a variety of common types of liquids, as well as excellent self-cleaning properties. In addition, the fluorine-free super-hydrophobic coatings obtained by the present invention have a certain durability effect, and still have a certain hydrophobic property after 100 times of linear friction and 120 minutes of washing, with contact angles of above 131.9° and above 132.7°, respectively.

[0035] Furthermore, the preferred scheme of the present invention can achieve better effects: the initial contact angles are all above 154.2°, and the water contact angles after 100 linear frictions and 120 minutes of washing are respectively above 150.2° and 149.4°, showing excellent hydrophobicity and durability. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 The test diagram of the fluorine-free super-hydrophobic coating obtained in Example 1; wherein, (a) is a diagram of the contact angle test process of the fluorine-free super-hydrophobic cotton fabric, (a) shows that the contact angle of the obtained fluorine-free super-hydrophobic coating is 154.2°; (b) is the process of the water column being bounced off the finished cotton fabric; (c) is the silver mirror phenomenon of the finished cotton fabric immersed in water;

[0037] Figure 2 Surface morphology of the fluorine-free super-hydrophobic coating obtained in Example 1.

[0038] Figure 3 The infrared spectra of the original cotton fabric and the OTS / HD-KH@SiO2 coated hydrophobic fabric obtained by Fourier transform infrared spectrometer;

[0039] Figure 4 The photos are of various common liquids (deionized water, water-soluble dye, cola, milk, coffee, and cooking oil) dropped onto the surface of the original cotton fabric and the fluorine-free super-hydrophobic coating;

[0040] Figure 5 The self-cleaning performance effect diagram of the fluorine-free super-hydrophobic coating obtained in Example 1; (a) is the self-cleaning process of active dye stains, and (b) is the self-cleaning process of dust stains.

[0041] Figure 6 The test results of the fabric friction resistance of the fluorine-free super hydrophobic coating obtained in Example 1 are shown in Figure (a) and the test results of the soap washing fastness. DETAILED DESCRIPTION

[0042] The present invention provides a fluorine-free super hydrophobic coating, wherein the fluorine-free super hydrophobic coating is finished on a cotton fabric, and the fluorine-free super hydrophobic coating comprises a hydrophobically modified silica layer attached to the cotton fabric;

[0043] The particle size of the hydrophobically modified silica is 15 to 70 nm, more preferably 15 to 20 nm.

[0044] The fluorine-free super hydrophobic coating provided by the present invention comprises a hydrophobic silica layer attached to a cotton fabric. In the present invention, the hydrophobic silica in the hydrophobic silica coating is preferably modifier-modified silica; the modifier is preferably trichlorooctadecylsilane, KH-560 and hexadecyltrimethoxysilane.

[0045] The present invention also provides a method for preparing the fluorine-free super-hydrophobic coating described in the above technical solution, comprising the following steps:

[0046] The silicon dioxide, a modifier, trichlorooctadecylsilane and an alcohol solvent are mixed and modified to obtain modified silicon dioxide;

[0047] Hydrolyzing KH-560 to obtain KH-560 sol;

[0048] KH-560 sol, modified silica and hexadecyltrimethoxysilane were mixed at a modification temperature of 70 to 90° C. for 3 h to obtain hydrophobic silica;

[0049] The modified silica sol is impregnated on cotton fabric, and pre-baked and baked to obtain the fluorine-free super-hydrophobic cotton fabric.

[0050] In the present invention, the particle size of the silicon dioxide is preferably 15 to 70 nm, more preferably 15 to 20 nm. The modifier is preferably trichlorooctadecylsilane, KH-560 and hexadecyltrimethoxysilane. In the present invention, the alcohol solvent is preferably ethanol.

[0051] In the present invention, the usage ratio of the silica to the modifier is preferably 1 g: (2-5) mL. In the present invention, the usage ratio of the silica to the alcohol solvent is preferably 1 g: (100-150 mL).

[0052] In the present invention, the mixing of the silica, the modifier OTS and the alcohol solvent preferably comprises the following steps: mixing the silica and the alcohol solvent for a first dispersion to obtain a silica dispersion; mixing the silica dispersion with the modifier OTS. In the present invention, the temperature of the first dispersion is preferably room temperature, the time is preferably 2 hours, and the amount of OTS added is 2-5 mL.

[0053] In the present invention, the KH-560 is hydrolyzed to obtain the KH-560 sol; the reagent for the hydrolysis of KH-560 is deionized water; the dosage ratio of the KH-560 and the reagent for the hydrolysis of KH-560 is 1g:(10-15mL); in the present invention, the hydrolysis temperature is preferably room temperature, and the time is preferably 0.5h.

[0054] After the modification, the KH-560 sol, modified silica and hexadecyltrimethoxysilane are mixed, the modification temperature is 70-90° C., and the time is 3 hours; the heating equipment is preferably an oil bath pot.

[0055] After obtaining the hydrophobically modified silica, the present invention coats the modified silica sol on cotton fabric, and performs drying and solidification to obtain fluorine-free super-hydrophobic cotton fabric.

[0056] In the present invention, the coating method preferably includes dipping and spraying. In the present invention, the dipping temperature of the hydrophobic sol is preferably room temperature, and the time is 2 to 10 minutes.

[0057] In the present invention, the curing temperature is preferably 90 to 150° C., more preferably 100 to 120° C.; the curing time is preferably 1 to 6 minutes, more preferably 2 to 3 minutes. The fluorine-free super-hydrophobic cotton fabric is obtained.

[0058] The present invention also provides the fluorine-free super-hydrophobic cotton fabric described in the above technical solution, the preparation method described in the above technical solution, and the application of the fluorine-free super-hydrophobic coating in the field of self-cleaning.

[0059] The preparation method of the fluorine-free super-hydrophobic cotton fabric provided by the present invention is described in detail below in conjunction with the embodiments, but they should not be construed as limiting the scope of protection of the present invention.

[0060] Example 1

[0061] Accurately weigh 0.3 g of nano-SiO2 particles and place them in a beaker containing 30 mL of anhydrous ethanol. Use an ultrasonic stirrer to disperse the mixture for 30 minutes. Add 5 mL (4.92 g) of OTS and react for 2 hours to obtain solution A.

[0062] 3 g of silane coupling agent KH-560 was added to another beaker containing 30 mL of deionized water, and the mixture was ultrasonically stirred using an ultrasonic stirrer for 30 minutes to promote the full hydrolysis of the silane coupling agent KH-560 in water, thereby preparing solution B.

[0063] The prepared solution A, solution B and 1 mL (0.89 g) of HDTMS were added to a 150 mL three-necked flask in sequence. During the addition process, 1 mol / L HCl solution was slowly added dropwise to the mixture to adjust the pH value of the solution between 4 and 5. The three-necked flask was placed in a magnetic stirring constant temperature oil bath, the temperature was set to 70 ° C, and the speed of the stirrer was adjusted to 1000 rpm. The mixture was mixed and reacted for 4 hours to finally obtain a hydrophobic OTS / HD-KH@SiO2 sol.

[0064] The cotton fabric was immersed in the prepared OTS / HD-KH@SiO2 sol, pre-baked for 10 min and then baked (120°C, 2 min) to obtain fluorine-free superhydrophobic cotton fabric.

[0065] The contact angle of the obtained transparent superhydrophobic coating is 154.2°, and it has good self-cleaning performance.

[0066] Figure 1 The water contact angle test diagram of the fluorine-free super-hydrophobic coating obtained in Example 1, wherein (a) is a diagram of the contact angle test process of the fluorine-free super-hydrophobic cotton fabric, (a) shows that the contact angle of the obtained fluorine-free super-hydrophobic coating is 154.2°; (b) is the process of the water column being bounced off by the treated cotton fabric; (c) is the silver mirror phenomenon exhibited by the treated cotton fabric immersed in water.

[0067] The infrared spectra of the original cotton fabric and the OTS / HD-KH@SiO2 coated hydrophobic fabric obtained by Fourier transform infrared spectrometer are shown in Figure 2 As shown. Hydrophobic cotton fabric and original cotton fabric at 3332cm -1 There is a stretching vibration peak of -OH at 2918cm, and the peak width and height of the original cotton fabric are wider than those of the treated cotton, which indirectly proves that some hydroxyl groups on the surface of the cotton fabric are replaced by hydrophobic materials, dehydration condensation occurs to form covalent bonds, and thus cross-linked on the fabric. -1 and 2851cm -1 There are stretching vibration peaks of methyl and methylene groups of long-chain alkyl groups in OTS at 1456 cm -1 The stretching vibration peak of methylene is at 814 cm -1 The Si-O stretching vibration peak appears at the bottom of the fabric, proving that the modified silica nanoparticles are successfully arranged on the fabric surface. This proves that the OTS / HD-KH@SiO2 coated hydrophobic fabric has been successfully prepared.

[0068] Figure 3 These are photos of various common liquids (deionized water, water-soluble dye, cola, milk, coffee, and cooking oil) being dropped onto the surface of the original cotton fabric and the fluorine-free super-hydrophobic coating. Figure 3 It can be seen that the obtained fluorine-free superhydrophobic cotton fabric exhibits excellent anti-fouling properties against many common types of liquids.

[0069] Reactive dyes and dust were used to simulate solid pollutants. Solid pollutant powder was sprinkled on the fluorine-free super-hydrophobic coating obtained in Example 1, and water was dripped on one end of the transparent super-hydrophobic coating. Figure 4 As shown in the figure, (a) is the self-cleaning process of active dye stains, and (b) is the self-cleaning process of dust stains. Figure 4 It can be seen that the prepared fluorine-free superhydrophobic cotton fabric has excellent self-cleaning performance.

[0070] Fabric friction resistance test According to the improved method of AA TCC 8-2001, the finished fabric is rubbed with a friction fastness tester, and the finished fabric is placed on a stainless steel ring, with the original cotton fabric as the lining cloth, and one cycle is considered one friction. Figure 6 (a) It can be seen that the contact angle of the treated cotton fabric decreases with the increase of the number of frictions. The main reason is that with the increase of the number of frictions, the micro / nano rough structure on the surface of the cotton fabric is destroyed, and some low surface energy substances are rubbed off, resulting in a continuous decrease in the water contact angle of the cotton fabric. After the treated cotton fabric is rubbed 100 times, the contact angle is 131.9°, which still maintains a certain hydrophobic property.

[0071] The soap fastness test is based on the first method of AATCC 61-2003. 0.37wt% soap flakes and 10 steel balls are added to the soap fastness instrument. Soap washing is carried out at 40℃. 45 minutes is regarded as one soap washing (equivalent to 5 ordinary washings). After soap washing, the fabric is rinsed with a large amount of water to remove the soap solution, and then dried at 80℃. The results are as follows Figure 6 As shown in (b), after 120 minutes of washing, the contact angle of OTS / HD-KH@SiO2 cotton fabric decreased from 154.4° to 132.7°, and it still had hydrophobic properties. This is mainly because the surface material of cotton fabric under the composite system is relatively stable. After 120 minutes of washing, the dense film tightly wrapped the nanoparticles to prevent them from falling off the fabric, and the degree of cross-linking was good.

[0072] Example 2

[0073] 0.3 g of nano-SiO2 particles were accurately weighed and placed in a beaker containing 30 mL of anhydrous ethanol. The mixture was dispersed using an ultrasonic stirrer for 30 minutes, and 4.92 g of HDTMS was added and reacted for 2 hours to obtain solution A.

[0074] 3 g of silane coupling agent KH-560 was added to another beaker containing 30 mL of deionized water, and the mixture was ultrasonically stirred using an ultrasonic stirrer for 30 minutes to promote the full hydrolysis of the silane coupling agent KH-560 in water, thereby preparing solution B.

[0075] The prepared solution A, solution B and 0.89 g of OTS were added to a 150 mL three-necked flask in sequence. During the addition process, 1 mol / L HCl solution was slowly added dropwise to the mixture to adjust the pH value of the solution between 4 and 5. The three-necked flask was placed in a magnetic stirring constant temperature oil bath, the temperature was set to 70 ° C, and the speed of the stirrer was adjusted to 1000 rpm. The mixture was mixed and reacted for 4 hours to finally obtain a hydrophobic OTS / HD-KH@SiO2 sol.

[0076] The prepared OTS / HD-KH@SiO2 sol was sprayed on the surface of cotton fabric, pre-baked for 10 min and then baked (120°C, 2 min) to obtain fluorine-free superhydrophobic cotton fabric.

[0077] The contact angle of the obtained transparent super-hydrophobic coating is 157.2°

[0078] According to the same test process as in Example 1, the fluorine-free super-hydrophobic cotton fabric obtained in this example exhibits excellent antifouling properties to a variety of common types of liquids (deionized water, water-soluble dye, cola, milk, coffee, cooking oil). In addition, the prepared fluorine-free super-hydrophobic cotton fabric has excellent self-cleaning properties.

[0079] According to the same fabric friction resistance and soap washing fastness tests in Example 1, the fluorine-free super hydrophobic coating obtained in this example has a certain durability effect. After 100 linear frictions and 120 minutes of washing, the water contact angles are 143.5° and 142.6°, respectively, and it still has good hydrophobic properties.

[0080] Example 3

[0081] Accurately weigh 0.3 g of nano-SiO2 particles and put them into a beaker containing 30 mL of anhydrous ethanol. Use an ultrasonic stirrer to disperse the mixture for 30 minutes, add 4.92 g of silane coupling agent KH-560, and react for 2 hours to obtain solution A.

[0082] 3 g of OTS was added into another beaker containing 30 mL of deionized water, and the mixture was ultrasonically stirred using an ultrasonic stirrer for 30 minutes to promote the full hydrolysis of OTS in water, thereby preparing a solution B.

[0083] The prepared solution A, solution B and 0.89 g of HDTMS were added to a 150 mL three-necked flask in sequence. During the addition process, 1 mol / L HCl solution was slowly added dropwise to the mixture to adjust the pH value of the solution between 4 and 5. The three-necked flask was placed in a magnetic stirring constant temperature oil bath, the temperature was set to 70 ° C, and the speed of the stirrer was adjusted to 1000 rpm. The mixture was mixed and reacted for 4 hours to finally obtain a hydrophobic OTS / HD-KH@SiO2 sol.

[0084] The prepared OTS / HD-KH@SiO2 sol was sprayed on the surface of cotton fabric, pre-baked for 10 min and then baked (120°C, 2 min) to obtain fluorine-free superhydrophobic cotton fabric.

[0085] The contact angle of the obtained transparent super-hydrophobic coating is 154.8°

[0086] According to the same test process as in Example 1, the fluorine-free super-hydrophobic cotton fabric obtained in this example exhibits excellent antifouling properties to a variety of common types of liquids (deionized water, water-soluble dye, cola, milk, coffee, cooking oil). In addition, the prepared fluorine-free super-hydrophobic cotton fabric has excellent self-cleaning properties.

[0087] According to the same fabric friction resistance and soap washing fastness tests in Example 1, the fluorine-free super hydrophobic coating obtained in this example has a certain durability effect. After 100 linear frictions and 120 minutes of washing, the water contact angles are 150.2° and 149.4°, respectively, and it still has excellent hydrophobic properties.

[0088] Comparative Example 1

[0089] 0.3 g of nano-SiO2 particles were accurately weighed and placed in a beaker containing 30 mL of anhydrous ethanol. The mixture was dispersed using an ultrasonic stirrer for 30 minutes, and 2 mL (1.97 g) of OTS was added and reacted for 2 hours to obtain solution A.

[0090] 3 g of silane coupling agent KH-560 was added to another beaker containing 30 mL of deionized water, and the mixture was ultrasonically stirred using an ultrasonic stirrer for 30 minutes to promote the full hydrolysis of the silane coupling agent KH-560 in water, thereby preparing solution B.

[0091] The prepared solution A, solution B and 1 mL (0.89 g) of HDTMS were added to a 150 mL three-necked flask in sequence. During the addition process, 1 mol / L HCl solution was slowly added dropwise to the mixture to adjust the pH value of the solution between 4 and 5. The three-necked flask was placed in a magnetic stirring constant temperature oil bath, the temperature was set to 70 ° C, and the speed of the stirrer was adjusted to 1000 rpm. The mixture was mixed and reacted for 4 hours to finally obtain a hydrophobic OTS / HD-KH@SiO2 sol.

[0092] The prepared OTS / HD-KH@SiO2 sol was sprayed on the surface of cotton fabric, pre-baked for 10 min and then baked (120°C, 2 min) to obtain fluorine-free superhydrophobic cotton fabric.

[0093] The contact angle of the obtained transparent superhydrophobic coating is 148.1°.

[0094] The above are all preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed by the present invention should be included in the technical protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope defined by the claims.

[0095] The matters not described in detail in the present invention are all known technologies to those skilled in the art.

Claims

1. A fluorine-free super-hydrophobic coating, characterized in that: The fluorine-free super-hydrophobic coating is attached to the cotton fabric, and the fluorine-free super-hydrophobic coating comprises a hydrophobically modified silica layer; the hydrophobic silica layer is prepared by modifying silica with a modifier; the modifier comprises trichlorooctadecylsilane, KH-560 and hexadecyltrimethoxysilane.

2. A method for preparing a fluorine-free super-hydrophobic coating according to claim 1, characterized in that: The following steps are involved: S1, mixing silica, a first modifier and an alcohol solvent to modify the silica to obtain hydrophobic silica; S2, dispersing the second modifier in water to obtain a mixed solution; S3, mixing the obtained hydrophobic silica, the mixed solution and the third modifier to obtain a fluorine-free super hydrophobic coating; The first modifier, the second modifier and the third modifier are independently selected from trichlorooctadecylsilane, KH-560 and hexadecyltrimethoxysilane, respectively, and the second modifier and the third modifier are different.

3. The preparation method according to claim 2, characterized in that: The first modifier, the second modifier, and the third modifier are different.

4. The preparation method according to claim 2, characterized in that: The first modifier is trichlorooctadecylsilane, the second modifier is KH-560, and the third modifier is hexadecyltrimethoxysilane; Alternatively, the first modifier is hexadecyltrimethoxysilane, the second modifier is KH-560, and the third modifier is trichlorooctadecylsilane; Alternatively, the first modifier is KH-560, the second modifier is trichlorooctadecylsilane, and the third modifier is hexadecyltrimethoxysilane.

5. The preparation method according to claim 2, characterized in that: The mass ratio of the first modifier, the second modifier and the third modifier is (4-8):(3-5):

1.

6. The preparation method according to claim 2, characterized in that: The mass ratio of the silicon dioxide to the first modifier in S1 is 1:(10-20); the amount ratio of the silicon dioxide to the alcohol solvent is 1g:(100-150mL).

7. The preparation method according to claim 2, characterized in that: The concentration of the second modifier dispersed in water in S2 is 0.1-0.5 g / mL.

8. A method for preparing a fluorine-free super-hydrophobic nano-silica cotton fabric, comprising coating the fluorine-free super-hydrophobic coating according to claim 1 on the cotton fabric, followed by drying and curing to obtain the fluorine-free super-hydrophobic cotton fabric.

9. The fluorine-free super hydrophobic fabric prepared by the method of claim 8.

10. Use of the fluorine-free super-hydrophobic coating according to claim 1 or the fluorine-free super-hydrophobic fabric according to claim 9 in the field of self-cleaning.

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