Super-hydrophobic coating for stainless steel and preparation method of super-hydrophobic coating

Abstract

The invention relates to the technical field of coatings, and discloses a super-hydrophobic coating for stainless steel and a preparation method thereof.The super-hydrophobic coating is obtained by performing esterification polymerization reaction on fluorine-containing diacid monomers and 1, 3-bis (4-hydroxybutyl) tetramethyldisiloxane; a polymer molecular chain of the coating contains a large amount of hydrophobic siloxane, fluorine-containing groups, benzene rings and ester groups, the hydrophobicity of a coating is remarkably improved, unique super-hydrophobicity is presented, meanwhile, siloxane and the benzene rings with high structural stability are contained, the wear resistance of the coating is improved, the retention rate of a water contact angle after friction is high, and the wear resistance is good. A polymer molecular chain of the coating contains a large number of carbamate groups, and forms strong interaction with the surfaces of metals such as stainless steel, so that the adhesion performance between the coating and the stainless steel is improved, and the adhesive force grade reaches grade 1.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of coating technology, in particular to a super-hydrophobic coating for stainless steel and a preparation method thereof. BACKGROUND

[0002] Super-hydrophobic materials have unique self-cleaning, anti-fouling, and corrosion-resistant characteristics, and are widely used in coatings, film materials, oil-water separation, and other aspects. Super-hydrophobic materials are usually composed of inorganic nano-filler, hydrophobic polysiloxane polymer, fluorine-containing low-surface-energy substance, etc. Patent CN118240428A discloses a corrosion-resistant super-hydrophobic wave-absorbing coating and a preparation method thereof. Through the synergistic effect of fluorosilane-modified micro-nano hierarchical titanium dioxide powder, fluorocarbon super-hydrophobic surface layer, and epoxy wave-absorbing bottom layer and fluorocarbon super-hydrophobic surface layer, excellent super-hydrophobic performance is exhibited, which can be applied to aluminum alloy, stainless steel, and other substrates. However, the super-hydrophobic coating of this patent needs to add micro-nano titanium dioxide powder and introduce fluorine-containing groups on the surface of the coating, which will reduce the surface energy of the coating, and reduce the adhesion and adhesion between the coating and the coating bottom layer, metal substrate, etc. SUMMARY

[0003] (I) The technical problem solved by the present application is to solve the problem that the surface of stainless steel and other metal substrates does not have super-hydrophobic effect, and the coating and the stainless steel and other substrates maintain good adhesion and adhesion.

[0004] (II) The technical solution of the present application is a preparation method of a super-hydrophobic coating: (1) Nitrogen is introduced into a flask, solvent, 3-hydroxy-5-(trifluoromethyl) benzoic acid, hexamethylene diisocyanate, and dibutyltin dilaurate are added, and after reaction, rotary evaporation is performed, column chromatography is used for separation, and a fluorine-containing diacid monomer is obtained, and the reaction formula is as follows: .

[0005] (2) Toluene, fluorine-containing diacid monomer, 1,3-bis(4-hydroxybutyl) tetramethyldisiloxane, and p-toluenesulfonic acid are added to a flask equipped with a condenser reflux tube and a water separator, and after reaction, rotary evaporation is performed, ethanol is used for washing, the product is added to butyl acetate, a defoaming agent is added after stirring, and a super-hydrophobic coating is obtained; the reaction formula is as follows: .

[0006] (3) The super-hydrophobic coating is poured on the surface of the substrate, and is baked and cured to obtain a super-hydrophobic coating.

[0007] Preferably, the solvent in (1) includes tetrahydrofuran, acetone, or toluene.

[0008] Preferably, the ratio of 3-hydroxy-5-(trifluoromethyl)benzoic acid, hexamethylene diisocyanate, dibutyl tin dilaurate in (1) is (2-2.2) mol:1 mol:(0.002-0.003) mol.

[0009] Preferably, the reaction temperature in (1) is 50-80 DEG C, and the reaction time is 4-6 h.

[0010] Preferably, the ratio of fluorine-containing diacid monomer, 1,3-bis(4-hydroxybutyl) tetramethyl disiloxane, p-toluenesulfonic acid in (2) is 1 mol:(0.9-1.1) mol:(0.08-0.11) mol.

[0011] Preferably, the reaction temperature in (2) is 100-110 DEG C, and the reaction time is 18-24 h.

[0012] Preferably, the temperature of baking and curing in (3) is 80-100 DEG C, and the time is 2-4 h.

[0013] Preferably, the super-hydrophobic coating is applied to the surface of metal substrates such as stainless steel.

[0014] (Three) beneficial technical effects: the present application utilizes fluorine-containing diacid monomer and 1,3-bis(4-hydroxybutyl) tetramethyl disiloxane to carry out esterification polymerization reaction, obtains super-hydrophobic coating, the polymer molecular chain of the coating contains a large number of hydrophobic siloxane, fluorine-containing groups, benzene rings and ester groups, significantly improves the hydrophobicity of the coating, does not need to add inorganic particles such as nano-titanium dioxide to form micro-nano rough structure, the water contact angle can reach 152.7-153.9 DEG C, presents unique super-hydrophobic performance, at the same time contains siloxane and high-structural-stability benzene ring, is beneficial to improve the wear resistance of the coating, the water contact angle retention rate is high after rubbing, and the wear resistance is good.

[0015] The polymer molecular chain of the coating of the present application contains a large number of urethane groups, forms strong interaction with the surface of metals such as stainless steel, improves the adhesion between the coating and the stainless steel, and the adhesion grade reaches grade 1. DETAILED DESCRIPTION

[0016] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application are described in detail below. In the following description, a large number of specific details are set forth in order to fully understand the present application, but the present application can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without departing from the connotation of the present application, therefore the present application is not limited by the specific embodiments disclosed below.

[0017] Example 1: (1) A flask with a condenser reflux tube was purged with nitrogen, and toluene, 80 mmol of 3-hydroxy-5-(trifluoromethyl)benzoic acid (CAS No. 328-69-8), 40 mmol of hexamethylene diisocyanate, and 0.12 mmol of dibutyltin dilaurate were added. The mixture was heated to 80°C and stirred for 4 h. The mixture was rotary evaporated and column chromatography was performed using ethyl acetate and petroleum ether as eluent to obtain the fluorine-containing diacid monomer.

[0018] (2) A flask with a condenser reflux tube and a water separator was charged with 50 mL of toluene, 50 mmol of the fluorine-containing diacid monomer, 50 mmol of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane, and 4.6 mmol of p-toluenesulfonic acid. The mixture was heated to 100°C and stirred for 24 h. The mixture was rotary evaporated and washed with ethanol. The product was added to butyl acetate, and 0.23 g of an antifoaming agent (AGITAN DF 6420, Mingling Chemicals) was added after stirring to obtain the super-hydrophobic coating.

[0019] (3) The super-hydrophobic coating was poured onto the surface of a substrate, and the mixture was baked at 80°C for 4 h to obtain the super-hydrophobic coating layer.

[0020] Example 2: (1) A flask with a condenser reflux tube was purged with nitrogen, and toluene, 80 mmol of 3-hydroxy-5-(trifluoromethyl)benzoic acid (CAS No. 328-69-8), 40 mmol of hexamethylene diisocyanate, and 0.12 mmol of dibutyltin dilaurate were added. The mixture was heated to 80°C and stirred for 4 h. The mixture was rotary evaporated and column chromatography was performed using ethyl acetate and petroleum ether as eluent to obtain the fluorine-containing diacid monomer.

[0021] (2) A flask with a condenser reflux tube and a water separator was charged with 50 mL of toluene, 50 mmol of the fluorine-containing diacid monomer, 50 mmol of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane, and 4.6 mmol of p-toluenesulfonic acid. The mixture was heated to 100°C and stirred for 24 h. The mixture was rotary evaporated and washed with ethanol. The product was added to butyl acetate, and 0.23 g of an antifoaming agent (AGITAN DF 6420, Mingling Chemicals) was added after stirring to obtain the super-hydrophobic coating.

[0022] (3) The super-hydrophobic coating was poured onto the surface of a substrate, and the mixture was baked at 80°C for 4 h to obtain the super-hydrophobic coating layer.

[0023] Example 3: (1) A flask with a condenser reflux tube was purged with nitrogen, and toluene, 80 mmol of 3-hydroxy-5-(trifluoromethyl)benzoic acid (CAS No. 328-69-8), 40 mmol of hexamethylene diisocyanate, and 0.12 mmol of dibutyltin dilaurate were added. The mixture was heated to 80°C and stirred for 4 h. The mixture was rotary evaporated and column chromatography was performed using ethyl acetate and petroleum ether as eluent to obtain the fluorine-containing diacid monomer.

[0024] (2) Into a flask equipped with a condenser, a reflux tube, and a water separator, 40 mL of toluene, 50 mmol of fluorine-containing diacid monomer, 45 mmol of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane, and 5.2 mmol of p-toluenesulfonic acid were added, heated to 110°C, stirred for 18 h, rotary evaporated, washed with ethanol, and the product was added to butyl acetate, 0.21 g of antifoaming agent was added after stirring to obtain a super-hydrophobic coating.

[0025] (3) The super-hydrophobic coating was poured onto the surface of the substrate, baked and cured at 90°C for 4 h to obtain a super-hydrophobic coating layer.

[0026] Comparative Example 1: (1) Into a flask equipped with a condenser, a reflux tube, and a water separator, 50 mL of toluene, 50 mmol of 1,6-hexanedioic acid, 50 mmol of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane, and 4.6 mmol of p-toluenesulfonic acid were added, heated to 100°C, stirred for 24 h, rotary evaporated, washed with ethanol, and the product was added to butyl acetate, 0.23 g of antifoaming agent was added after stirring to obtain a coating.

[0027] (2) The coating was poured onto the surface of the substrate, baked and cured at 80°C for 4 h to obtain a coating layer.

[0028] Comparative Example 2: (1) Into a flask equipped with a condenser, a reflux tube, and a water separator, 50 mL of toluene, 50 mmol of 1,6-hexanedioic acid, 50 mmol of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane, and 4.6 mmol of p-toluenesulfonic acid were added, heated to 100°C, stirred for 24 h, rotary evaporated, washed with ethanol, and the product was added to butyl acetate, 0.23 g of antifoaming agent was added after stirring to obtain a coating.

[0029] (2) The coating was poured onto the surface of the substrate, baked and cured at 80°C for 4 h to obtain a coating layer.

[0030] Comparative Example 3: (1) Into a flask equipped with a condenser, a reflux tube, and a water separator, 50 mL of toluene, 50 mmol of 1,6-hexanedioic acid, 50 mmol of 1,3-bis(4-hydroxybutyl)tetramethyldisiloxane, and 4.6 mmol of p-toluenesulfonic acid were added, heated to 100°C, stirred for 24 h, rotary evaporated, washed with ethanol, and the product was added to butyl acetate, 0.23 g of antifoaming agent was added after stirring to obtain a coating. .

[0031] (2) Add 50 mL of toluene, 50 mmol of fluorine-containing diacid monomer, 50 mmol of 1,3-bis(4-hydroxybutyl) tetramethyldisiloxane, 4.6 mmol of p-toluenesulfonic acid into a flask equipped with a condenser reflux tube and a water separator, heat to 100°C, stir for 24 h, rotary evaporation, ethanol washing, the product is added to butyl acetate, after stirring, 0.23 g of antifoaming agent is added, and a coating is obtained.

[0032] (3) Pour the coating on the surface of the substrate, bake and cure at 80°C for 4 h to obtain a coating layer.

[0033] Comparative Example 4: (1) Add 50 mL of toluene, 50 mmol of 2,5-bis(trifluoromethyl) terephthalic acid (CAS No. 366008-67-5), 50 mmol of 1,3-bis(4-hydroxybutyl) tetramethyldisiloxane, 4.6 mmol of p-toluenesulfonic acid into a flask equipped with a condenser reflux tube and a water separator, heat to 100°C, stir for 24 h, rotary evaporation, ethanol washing, the product is added to butyl acetate, after stirring, 0.23 g of antifoaming agent is added, and a coating is obtained.

[0034] (2) Pour the coating on the surface of the substrate, bake and cure at 80°C for 4 h to obtain a coating layer.

[0035] Test the water contact angle of the coating according to the GB / T 30693-2014 standard. Paste 325 mesh sandpaper on the bottom of a 1 kg weight, tie the weight with a thin rope, and place the weight on one end of the stainless steel coating surface, pull the weight from one end of the stainless steel coating to the other end at a rate of 10 cm / s, a total of 30 times of back and forth friction, and then test the water contact angle.

[0036] Test the adhesion grade of the coating according to the GB / T 9286-2021 standard.

[0037] Table 1 Performance of the coating

[0038] The coating of Example 1-Example 3 contains a large amount of hydrophobic siloxane, fluorine-containing group, benzene ring and ester group in the molecular chain, which significantly improves the hydrophobicity of the coating, and the water contact angle reaches 152.7-153.9°C, showing unique superhydrophobic performance. At the same time, the coating contains siloxane and benzene ring with high structural stability, which is beneficial to improve the wear resistance of the coating, and the water contact angle retention rate is high after friction, and the wear resistance is good. At the same time, the polymer molecular chain of the coating contains a large amount of urethane groups, which forms a strong interaction with the stainless steel surface, improves the adhesion between the coating and the stainless steel, and the adhesion grade reaches level 1.

[0039] The 1,6-hexanedioic acid and the prepared coating of Comparative Example 1 do not contain fluorine element, benzene ring and carbamate group, the water contact angle of the coating is low, the coating does not have super-hydrophobic property, and the adhesion is only 3 grade.

[0040] The diphenyldicarboxylic acid and the prepared coating of Comparative Example 2 do not contain fluorine element and carbamate group, the water contact angle of the coating is low, the coating does not have super-hydrophobic property, and the adhesion is only 3 grade.

[0041] The prepared coating of the diacid monomer of Comparative Example 3 does not contain fluorine element, the water contact angle of the coating is low, and the coating does not have super-hydrophobic property.

[0042] The 2,5-bis(trifluoromethyl)terephthalic acid and the prepared coating of Comparative Example 4 do not contain carbamate group, and the adhesion of the coating is only 3 grade.

[0043] The above is only an example and description of the present application, and those skilled in the art can make various modifications or supplements to the described specific examples or replace them with similar ways, as long as they do not deviate from the invention or exceed the scope defined by the present claims, which shall belong to the protection scope of the present application.

Claims

1. A method for producing a superhydrophobic coating, characterized by, The preparation method is as follows: (1) adding toluene, fluorine-containing diacid monomer, 1,3-bis(4-hydroxybutyl) tetramethyl disiloxane, p-toluenesulfonic acid into a flask equipped with a condenser reflux tube and a water separator, rotary evaporation after reaction, ethanol washing, adding the product into butyl acetate, adding an antifoaming agent after stirring, and obtaining a super-hydrophobic coating; (2) pouring the super-hydrophobic coating on the surface of a substrate, baking and curing to obtain a super-hydrophobic coating layer.

2. The method for preparing a superhydrophobic coating according to claim 1, characterized in that, The ratio of the fluorine-containing diacid monomer, 1,3-bis(4-hydroxybutyl) tetramethyl disiloxane and p-toluenesulfonic acid in (1) is 1 mol:(0.9-1.1) mol:(0.08-0.11) mol.

3. The method of claim 1, wherein the method further comprises: The reaction temperature in (1) is 100-110℃, and the reaction time is 18-24h.

4. The method of claim 1, wherein the superhydrophobic coating is prepared by a method comprising: The baking and curing temperature in (2) is 80-100℃, and the time is 2-4h.

5. The method of claim 1, wherein the superhydrophobic coating is prepared by a method comprising: The preparation method of the fluorine-containing diacid monomer is as follows: introducing nitrogen into a flask, adding a solvent, 3-hydroxy-5-(trifluoromethyl) benzoic acid, hexamethylene diisocyanate, dibutyl tin dilaurate, rotary evaporation after reaction, column chromatography separation, and obtaining the fluorine-containing diacid monomer.

6. The method of claim 1, wherein the superhydrophobic coating is prepared by a method comprising: The solvent includes tetrahydrofuran, acetone or toluene.

7. The method of claim 1, wherein the superhydrophobic coating is prepared by a method comprising: The ratio of 3-hydroxy-5-(trifluoromethyl) benzoic acid, hexamethylene diisocyanate and dibutyl tin dilaurate is (2-2.2) mol:1 mol:(0.002-0.003) mol.

8. The method of claim 1, wherein the superhydrophobic coating is prepared by, The reaction temperature is 50-80℃, and the reaction time is 4-6h.

9. A super-hydrophobic coating layer obtained by the preparation method of any one of claims 1-8.

10. Application of the super-hydrophobic coating layer of claim 9 in stainless steel.

Images