Preparation method of organic silicon modified waterborne polyurethane wear-resistant anticorrosive paint

Abstract

The invention relates to an organic silicon modified waterborne polyurethane wear-resistant anticorrosive coating which is prepared from organic silicon modified waterborne polyurethane, graphene grafted silicon dioxide nanotubes, polytetrafluoroethylene powder, sodium dodecyl benzene sulfonate, a polysiloxane defoaming agent, a polyvinyl alcohol flatting agent, a cosolvent and water. The organic silicon modified waterborne polyurethane wear-resistant, corrosion-resistant and wear-resistant coating prepared by the invention has excellent adhesive force, corrosion resistance, wear resistance, salt fog resistance and water resistance; the wear-resistant and anticorrosive paint is widely applied to metal structures of buildings, chemical engineering, petroleum and the like.

Description

Technical Field

[0001] The invention relates to a method for preparing an organosilicon-modified waterborne polyurethane wear-resistant and anticorrosive coating, and belongs to the field of functional materials and composite materials. Background Art

[0002] Corrosion can cause the surface of metal materials to be gradually destroyed, weakening their strength and structural integrity, and eventually leading to equipment or structural failure. Anti-corrosion measures can significantly extend the service life of metal materials and reduce the frequency of replacement or repair. Applying organic coatings on metal surfaces is an effective method for metal corrosion and wear resistance. Among many polymers, waterborne polyurethane (WPU) has attracted much attention due to its low volatile organic compounds (VOC), environmental friendliness, excellent mechanical properties and good chemical stability. However, due to the introduction of hydrophilic groups, the hardness, water resistance and corrosion resistance of waterborne polyurethane coatings have decreased, which greatly limits its development and application.

[0003] As a two-dimensional nanomaterial, graphene has attracted widespread attention due to its unique properties such as large specific surface area, excellent mechanical strength, low chemical activity, high thermal conductivity and electrical conductivity. Recently, many researchers have begun to improve the comprehensive properties of waterborne polyurethane by adding graphene and its derivatives (such as graphene oxide and functionalized graphene). Many studies have found that the comprehensive properties of waterborne polyurethane (WPU) can be improved by adding graphene and its derivatives. For example, Wang et al. prepared functionalized graphene-reinforced polyurethane nanocomposite coatings by the sol–gel method. The experimental results showed that the tensile strength and Young's modulus of the coating were improved (Wang X. et al., Fabrication and characterization ofgraphene-reinforced waterborne polyurethane nanocomposite coatings by thesol–gel method. Surf. Coat. Technol. 2012, 206, 4778). Zhang et al. prepared waterborne polyurethane / FGO composites by self-made polymer modified graphene oxide. The experimental results showed that the water resistance and tensile strength of WPU / FGO membrane were significantly improved (Zhang F et al., A novel and feasible approach for polymeramine modified graphene oxide to improve water resistance, thermal, and mechanical ability of waterborne polyurethane. Appl. Surf. Sci.2019, 491,301). How to prepare modified graphene and add it to the waterborne polyurethane system to further improve the wear resistance and corrosion resistance of the material has become a hot topic in scientific research. Summary of the invention The purpose of the present invention is to provide a method for preparing a silicone-modified waterborne polyurethane wear-resistant and anti-corrosion coating and its use, so as to solve the above-mentioned problems existing in the prior art.

[0005] The present invention is achieved through the following technical solutions: A method for preparing a silicone-modified waterborne polyurethane wear-resistant and anti-corrosion coating comprises the following steps: S1, preparing graphene-grafted silica nanotubes and water-based silicone-modified polyurethane respectively; S2. Disperse polytetrafluoroethylene powder, sodium dodecylbenzene sulfonate and the graphene-grafted silica nanotubes in an ethanol solution, mix well, add water-based silicone-modified polyurethane, ball mill and disperse, add a defoamer and a leveling agent, stir and disperse at high speed to obtain a water-based silicone-modified water-based polyurethane wear-resistant and anti-corrosion coating.

[0006] As a preferred embodiment, the preparation method of the graphene-grafted silica nanotubes is: The graphene is immersed in a mixed solution of sulfuric acid and nitric acid, and after activation, it is immersed in a thionyl chloride solution to obtain acyl chloride-modified graphene; After mixing anhydrous ethanol, acetone and γ-aminopropyltriethoxysilane, adjusting the pH value to 4-6, adding silica nanotubes, and reacting at 70-80°C to obtain surface amino-modified silica nanotubes; The surface aminated silica nanotubes, acyl chloride modified graphene, N,N -Dimethylformamide and triethylamine are mixed and reacted at 110-130°C under the protection of nitrogen to obtain graphene-grafted silica nanotubes.

[0007] As a preferred embodiment, the mass ratio of γ-aminopropyltriethoxysilane to silica nanotubes is (10-20):(1-3); in the mixed solution of sulfuric acid and nitric acid, the mass ratio of sulfuric acid to nitric acid is 3:1.

[0008] As a preferred embodiment, the preparation method of the water-based silicone-modified polyurethane is: After isophorone diisocyanate, hydroxy-terminated dimethylsilane and acetone are mixed, castor oil and butanone are added, reacted at 50-60°C, cooled to room temperature, triethylamine is added, stirred at a low speed, deionized water is added, and stirred at a high speed to obtain a water-based silicone-modified polyurethane.

[0009] As a preferred embodiment, the mass ratio of isophorone diisocyanate to hydroxy-terminated dimethylsilane is (7-10): (1-2).

[0010] As a preferred embodiment, the rotation speed of the low-speed stirring is 300-500 rpm, and the rotation speed of the high-speed stirring is 800-1000 rpm.

[0011] As a preferred embodiment, the mass ratio of the polytetrafluoroethylene powder to the graphene-grafted silica nanotubes is (1-2): (5-8).

[0012] As a preferred solution, the defoaming agent is selected from polysiloxane defoaming agents; and the leveling agent is selected from polyvinyl alcohol leveling agents.

[0013] As a preferred embodiment, the rotation speed of the high-speed stirring in step S2 is 800-1200 rpm.

[0014] A use of the organic silicon modified waterborne polyurethane wear-resistant and anti-corrosion coating obtained by the above-mentioned preparation method in metal wear-resistant and anti-corrosion.

[0015] The basic implementation principle of the present invention is: 1. First, the graphene is acidified to introduce carboxyl groups on its surface. The acidified graphene reacts with thionyl chloride to introduce acyl chloride groups to obtain acyl chloride-modified graphene.

[0016] 2. The silica nanotubes are reacted with γ-aminopropyltriethoxysilane under acidic conditions to obtain surface-aminated silica nanotubes, which are then reacted with acyl chloride-modified graphene using the surface amino activity to obtain graphene-grafted silica nanotubes.

[0017] 3. The isophorone diisocyanate, hydroxy-terminated dimethylsilane and castor oil are reacted to generate carbamate groups through addition reaction, and finally the polyurethane is reacted with dihydroxymethylpropionic acid and triethylamine in sequence to improve the water solubility of the polyurethane.

[0018] Compared with the prior art, the present invention has the following beneficial effects: 1. Grafting silica nanotubes onto graphene promotes the dispersibility of graphene in waterborne polyurethane and improves the performance of polyurethane materials to produce a significant synergistic effect.

[0019] 2. Add hydroxy-terminated dimethylsilane to the polyurethane reaction system to obtain silicone-modified polyurethane. Taking advantage of the low surface energy of silicone, the modified polyurethane material has better hydrophobicity and anti-pollution properties, greatly improving its anti-corrosion effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings: Figure 1 This is a flow chart for the preparation of the silicone-modified waterborne polyurethane wear-resistant and anti-corrosion coating of Example 1. DETAILED DESCRIPTION

[0021] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0022] Example 1 (1) Preparation of graphene oxide grafted silica nanotubes 0.3 g of graphene was soaked in a mixed solution of sulfuric acid and nitric acid (the mass ratio of sulfuric acid to nitric acid was 3:1) for 5 h, washed and dried to obtain activated graphene. The activated graphene was soaked in a dichlorothionyl solution for 100 min to obtain acyl chloride-modified graphene. 100 mL of anhydrous ethanol, 10 mL of acetone, and 20 g of γ-aminopropyltriethoxysilane were added to a three-necked flask, the pH was adjusted to 4.5 with acetic acid, 3 g of silica nanotubes were added, and the reaction was carried out at 75 ° C for 5 h. Then centrifuged, washed with anhydrous ethanol, and dried to obtain surface amino-modified silica nanotubes.

[0023] Take 1 g of amino-modified silica nanotubes, 0.1 g of acyl chloride-modified graphene, and 200 mL of N,N -dimethylformamide and 10 mL triethylamine were placed in a three-necked flask, nitrogen was introduced, and the mixture was reacted at 120°C for 24 h. After cooling to room temperature, the mixture was centrifuged and dried to obtain graphene-grafted silica nanotubes.

[0024] (2) Preparation of waterborne silicone-modified polyurethane 5 g of isophorone diisocyanate, 0.5 g of hydroxy-terminated dimethylsilane, and 10 mL of acetone were added to a three-necked flask, dissolved under magnetic stirring, 6 g of castor oil and 50 mL of butanone were added, and the mixture was reacted at 55°C for 80 min. After cooling to room temperature, 1.5 g of dihydroxymethylpropionic acid was added, and the mixture was reacted at 60°C for 2 h. After cooling to room temperature, triethylamine was added, and the mixture was stirred at 300 rpm for 5 min. Deionized water was added, and the mixture was stirred at 1000 rpm for 30 min to obtain a waterborne silicone-modified polyurethane.

[0025] (3) Preparation of water-based silicone-modified polyurethane wear-resistant and anti-corrosion coating 0.1 g polytetrafluoroethylene powder, 0.5 g graphene grafted silica nanotubes, and 0.2 g sodium dodecylbenzene sulfonate were dispersed in 100 mL of 5% ethanol solution, and ultrasonically dispersed for 1 hour, and 100 g water-based silicone modified polyurethane was added, and ground and dispersed for 6 hours using a ball mill. Finally, 2.5 g polysiloxane defoamer and 2.5 g polyvinyl alcohol leveling agent were added, and the high-speed stirrer was stirred and dispersed for 10 minutes at 1000 rpm to obtain a water-based silicone modified polyurethane wear-resistant and anti-corrosion coating. The preparation process is as follows: Figure 1 shown.

[0026] The coating prepared in Example 1 has an adhesion of 0 and a hardness of 3H. The salt spray resistance test shows that after the coating is immersed for 500 h, no corrosion products or rust are generated. The electrochemical test results show that the corrosion potential of the coating is -0.554 mV and the corrosion current is 1.87×10 -7 nA / cm 2 , the corrosion efficiency is 0.003 mm / a.

[0027] Example 2 (1) Preparation of graphene oxide grafted silica nanotubes 0.3 g of graphene was soaked in a mixed solution of sulfuric acid and nitric acid (the mass ratio of sulfuric acid to nitric acid was 3:1) for 5 h, washed and dried to obtain activated graphene. The activated graphene was soaked in a dichlorothionyl solution for 100 min to obtain acyl chloride-modified graphene. 100 mL of anhydrous ethanol, 10 mL of acetone, and 15 g of γ-aminopropyltriethoxysilane were added to a three-necked flask, the pH was adjusted to 5 with acetic acid, 2 g of silica nanotubes were added, and the reaction was carried out at 80 ° C for 5 h. Then centrifuged, washed with anhydrous ethanol, and dried to obtain surface amino-modified silica nanotubes.

[0028] Take 1.2 g of amino-modified silica nanotubes, 0.15 g of acyl chloride-modified graphene, and 200 mL of N,N -Dimethylformamide and 10 mL of triethylamine were placed in a three-necked flask, nitrogen was introduced, and the mixture was reacted at 110°C for 24 h. After cooling to room temperature, the mixture was centrifuged and dried to obtain graphene-grafted silica nanotubes.

[0029] (2) Preparation of waterborne silicone-modified polyurethane 4 g of isophorone diisocyanate, 0.55 g of hydroxy-terminated dimethylsilane, and 10 mL of acetone were added to a three-necked flask, dissolved under magnetic stirring, 6 g of castor oil and 50 mL of butanone were added, reacted at 60°C for 100 min, and after cooling to room temperature, 1.5 g of dihydroxymethylpropionic acid was added, reacted at 55°C for 3 h, cooled to room temperature, triethylamine was added, stirred at a low speed of 300 rpm for 5 min, deionized water was added, and stirred at a speed of 1000 rpm for 30 min to obtain water-based silicone-modified polyurethane.

[0030] (3) Preparation of water-based silicone-modified polyurethane wear-resistant and anti-corrosion coating 0.15 g of polytetrafluoroethylene powder, 0.6 g of graphene-grafted silica nanotubes, and 0.2 g of sodium dodecylbenzene sulfonate were dispersed in 100 mL of 5% ethanol solution and ultrasonically dispersed for 1 hour. 100 g of water-based silicone-modified polyurethane was added and ground and dispersed with a ball mill for 6 hours. Finally, 2.5 g of polysiloxane defoamer and 2.5 g of polyvinyl alcohol leveling agent were added respectively, and the mixture was stirred and dispersed at 1000 rpm in a high-speed stirrer for 10 min to obtain a water-based silicone-modified polyurethane wear-resistant and anti-corrosion coating.

[0031] The coating prepared in Example 2 has an adhesion of 0 and a hardness of 3H. The salt spray resistance test shows that after the coating is immersed for 500 h, no corrosion products or rust are generated. The electrochemical test results show that the corrosion potential of the coating is -0.533 mV and the corrosion current is 1.81×10 -7 nA / cm 2 , the corrosion efficiency is 0.0035 mm / a.

[0032] Example 3 (1) Preparation of graphene oxide grafted silica nanotubes 0.3 g of graphene was soaked in a mixed solution of sulfuric acid and nitric acid (the mass ratio of sulfuric acid to nitric acid was 3:1) for 5 h, washed and dried to obtain activated graphene. The activated graphene was soaked in a dichlorothionyl solution for 100 min to obtain acyl chloride-modified graphene. 100 mL of anhydrous ethanol, 10 mL of acetone, and 18 g of γ-aminopropyltriethoxysilane were added to a three-necked flask, the pH was adjusted to 5 with acetic acid, 3 g of silica nanotubes were added, and the reaction was carried out at 75 ° C for 5 h. Then centrifuged, washed with anhydrous ethanol, and dried to obtain surface amino-modified silica nanotubes.

[0033] Take 1 g of amino-modified silica nanotubes, 0.15 g of acyl chloride-modified graphene, and 200 mL of N,N-dimethylformamide and 10 mL triethylamine were placed in a three-necked flask, nitrogen was introduced, and the mixture was reacted at 125°C for 24 h. After cooling to room temperature, the mixture was centrifuged and dried to obtain graphene-grafted silica nanotubes.

[0034] (2) Preparation of waterborne silicone-modified polyurethane 5 g of isophorone diisocyanate, 0.60 g of hydroxy-terminated dimethylsilane, and 10 mL of acetone were added to a three-necked flask, dissolved under magnetic stirring, 6 g of castor oil and 50 mL of butanone were added, and the mixture was reacted at 58°C for 80 min. After cooling to room temperature, 1.5 g of dihydroxymethylpropionic acid was added, and the mixture was reacted at 57°C for 3 h. After cooling to room temperature, triethylamine was added, and the mixture was stirred at a low speed of 300 rpm for 5 min. Deionized water was added, and the mixture was stirred at a speed of 1000 rpm for 30 min to obtain a water-based silicone-modified polyurethane.

[0035] (3) Preparation of water-based silicone-modified polyurethane wear-resistant and anti-corrosion coating 0.15 g of polytetrafluoroethylene powder, 0.7 g of graphene-grafted silica nanotubes, and 0.2 g of sodium dodecylbenzene sulfonate were dispersed in 100 mL of 5% ethanol solution and ultrasonically dispersed for 1 hour. 100 g of water-based silicone-modified polyurethane was added and ground and dispersed with a ball mill for 6 hours. Finally, 3 g of polysiloxane defoamer and 3 g of polyvinyl alcohol leveling agent were added respectively, and the mixture was stirred and dispersed at 1000 rpm in a high-speed stirrer for 10 min to obtain a water-based silicone-modified polyurethane wear-resistant and anti-corrosion coating.

[0036] The coating prepared in Example 3 has an adhesion of level 0 and a hardness of 3H. The salt spray resistance test shows that after the coating is immersed for 500 h, no corrosion products or rust are generated. The electrochemical test results show that the corrosion potential of the coating is -0.536 mV and the corrosion current is 1.80×10 -7 nA / cm 2 , the corrosion efficiency is 0.0035 mm / a.

[0037] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that in step (3), "graphene-grafted silica nanotubes" is replaced by "graphene". The adhesion of the coating prepared in Comparative Example 1 is level 0 and the hardness is 3H. The salt spray resistance test shows that after the coating is immersed for 500 h, the coating does not produce corrosion products and rust. The electrochemical test results show that the corrosion potential of the coating is -0.812 mV and the corrosion current is 5.22×10 -7 nA / cm 2 , the corrosion efficiency is 0.0067 mm / a.

[0038] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that the amount of "graphene grafted silica nanotubes" added in step (3) is 0. The coating prepared in Comparative Example 2 has an adhesion of level 0 and a hardness of 2H. The salt spray resistance test shows that after the coating is immersed for 500 h, corrosion products and rust are generated in the coating. The electrochemical test results show that the corrosion potential of the coating is -0.912 mV and the corrosion current is 2.88×10 -6 nA / cm 2 , the corrosion efficiency is 0.025 mm / a.

[0039] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that the amount of polytetrafluoroethylene added in step (3) is 0. The adhesion of the coating prepared in Comparative Example 3 is level 0 and the hardness is 2H. The salt spray resistance test shows that after the coating is immersed for 500 h, the coating produces no corrosion products and rust. The electrochemical test results show that the corrosion potential of the coating is -0.549 mV and the corrosion current is 1.98×10 -7 nA / cm 2 , the corrosion efficiency is 0.004 mm / a.

[0040] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various modifications or variations within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A method for preparing a silicone-modified waterborne polyurethane wear-resistant and anti-corrosion coating, characterized in that: The steps include: S1, preparing graphene-grafted silica nanotubes and water-based silicone-modified polyurethane respectively; S2. Disperse polytetrafluoroethylene powder, sodium dodecylbenzene sulfonate and the graphene-grafted silica nanotubes in an ethanol solution, mix well, add water-based silicone-modified polyurethane, ball mill and disperse, add a defoamer and a leveling agent, stir and disperse at high speed to obtain a water-based silicone-modified water-based polyurethane wear-resistant and anti-corrosion coating.

2. The method for preparing the silicone-modified waterborne polyurethane wear-resistant and anticorrosive coating according to claim 1, characterized in that: The preparation method of the graphene-grafted silica nanotubes is as follows: The graphene is immersed in a mixed solution of sulfuric acid and nitric acid, and after activation, it is immersed in a thionyl chloride solution to obtain acyl chloride-modified graphene; After mixing anhydrous ethanol, acetone and γ-aminopropyltriethoxysilane, adjusting the pH value to 4-6, adding silica nanotubes, and reacting at 70-80°C to obtain surface amino-modified silica nanotubes; The surface aminated silica nanotubes, acyl chloride modified graphene, N,N -Dimethylformamide and triethylamine are mixed and reacted at 110-130°C under the protection of nitrogen to obtain graphene-grafted silica nanotubes.

3. The method for preparing the silicone-modified waterborne polyurethane wear-resistant and anticorrosive coating according to claim 2, characterized in that: The mass ratio of the γ-aminopropyltriethoxysilane to the silicon dioxide nanotubes is (10-20):(1-3); in the mixed solution of sulfuric acid and nitric acid, the mass ratio of sulfuric acid to nitric acid is 3:

1.

4. The method for preparing the silicone-modified waterborne polyurethane wear-resistant and anticorrosive coating according to claim 1, characterized in that: The preparation method of the water-based silicone-modified polyurethane is: After isophorone diisocyanate, hydroxy-terminated dimethylsilane and acetone are mixed, castor oil and butanone are added, reacted at 50-60°C, cooled to room temperature, triethylamine is added, stirred at a low speed, deionized water is added, and stirred at a high speed to obtain a water-based silicone-modified polyurethane.

5. The method for preparing the organic silicon modified waterborne polyurethane wear-resistant and anticorrosive coating according to claim 4, characterized in that: The mass ratio of isophorone diisocyanate to hydroxyl-terminated dimethylsilane is (7-10): (1-2).

6. The method for preparing the silicone-modified waterborne polyurethane wear-resistant and anticorrosive coating according to claim 4, characterized in that: The rotation speed of the low-speed stirring is 300-500 rpm, and the rotation speed of the high-speed stirring is 800-1000 rpm.

7. The method for preparing the waterborne organosilicon-modified waterborne polyurethane wear-resistant and anticorrosive coating according to claim 1, characterized in that: The mass ratio of the polytetrafluoroethylene powder to the graphene-grafted silica nanotubes is (1-2): (5-8).

8. The method for preparing the silicone-modified waterborne polyurethane wear-resistant and anticorrosive coating according to claim 1, characterized in that: The defoaming agent is selected from polysiloxane defoaming agents; and the leveling agent is selected from polyvinyl alcohol leveling agents.

9. The method for preparing the silicone-modified waterborne polyurethane wear-resistant and anticorrosive coating according to claim 1, characterized in that: The rotation speed of the high-speed stirring described in step S2 is 800~1200rpm.

10. Use of the organic silicon modified waterborne polyurethane wear-resistant and anti-corrosion coating obtained by the preparation method according to claim 1 in metal wear resistance and corrosion protection.

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