Superhydrophobic coatings with excellent mechanical properties and their applications

Abstract

This invention provides a superhydrophobic coating with excellent mechanical properties, and further offers applications for the superhydrophobic coating in the field of cured coatings. [Solution] The superhydrophobic coating is composed of three components, A, B, and C. Component A contains urea-modified aminosilicone oil, hydrophobic silica slurry, composite wheat straw fiber powder, organic solvent, and defoaming agent. Component B is ethyl orthosilicate, and component C is an organotin drying agent. In application, the three components A, B, and C are mixed in specific ratios, applied, and cured at room temperature or by heating to form a superhydrophobic cured coating. The resulting coating has excellent overall performance, superior superhydrophobic properties, excellent mechanical properties, and enables high-value utilization of agricultural waste wheat straw, making it highly promising for future applications.

Description

Technical Field

[0001] The present invention relates to superhydrophobic paints, particularly to superhydrophobic paints having excellent mechanical properties, and further to uses in the field of cured coatings of the above superhydrophobic paints.

Background Art

[0002] Superhydrophobic coatings exhibit remarkable application values in the fields of self-cleaning, anti-icing and anti-corrosion. The core of their performance lies in achieving excellent effects with a water contact angle > 150° and a roll angle close to 0° through the synergistic effect of a micro-nano concave-convex structure and low surface energy substances. The current mainstream manufacturing method is to form a microporous structure by depositing hydrophobic nanoparticles (such as hydrophobic silica). However, such coatings have insufficient mechanical strength and poor wear resistance, so when subjected to external forces, their performance easily fails and the superhydrophobicity is lost. In addition, it is difficult for the reinforcing materials added to improve the mechanical properties to meet the process requirements for constructing an ideal micro-nano structure. As a result, it is difficult to achieve both superhydrophobicity and mechanical properties, which has been a long-standing technical problem in the industry.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Object of the Invention: The object of the present invention is to provide a superhydrophobic paint having excellent mechanical properties, and further to provide uses in the field of cured coatings of the above superhydrophobic paint.

Means for Solving the Problems

[0004] Technical Solution: The present invention is a superhydrophobic paint having excellent mechanical properties, which is produced by synergistically compounding component A, component B and component C, and is as follows in terms of weight percentage. Component A is 35% - 50% of urea group-modified amino silicone oil, 25% - 40% of hydrophobic silica slurry, 1% - 5% of composite wheat straw fiber powder, 10% - 25% of organic solvent, and 0.1% - 1% of defoamer. The urea-modified aminosilicone oil is produced by reacting 3-isocyanatopropyltrimethoxysilane with an aminosilicone oil having an amino acid value of 0.5 to 1.8 mmol / g under anhydrous and oxygen-free conditions at 50°C to 70°C for 8 to 24 hours, and is used to provide a low surface energy matrix. The composite wheat straw fiber powder is produced by modifying wheat straw fiber powder (200 to 500 mesh) with vinyl silicone oil, hydrogen-containing silicone oil, and a platinum catalyst, and is used as a macro-reinforcement phase to improve mechanical properties. The hydrophobic silica slurry is produced by dispersing hydrophobic silica produced by a gas-phase method in an organic solvent with a wetting dispersant, and constructs a superhydrophobic structure as a micro-roughness unit. Component B is ethyl orthosilicate, a curing agent (with a silica content of 28% to 40%), which is used to cross-link and harden, forming a dense coating. Component C is an organotin drying agent (di-n-butyltin dilaurate, dibutyltin diacetate, or dioctyltin dilaurate) and is used to adjust the curing rate.

[0005] In the aforementioned component A, the urea group-modified aminosilicone oil is obtained by reacting and modifying a mixture of 3-isocyanatopropyltrimethoxysilane and aminosilicone oil. The manufacturing method involves mixing 3-isocyanatopropyltrimethoxysilane and aminosilicone oil in an anhydrous, oxygen-free environment and reacting them for 8 to 24 hours at a temperature range of 50°C to 70°C. The amino acid value range of the aminosilicone oil is 0.5 to 1.8 mmol / g. Depending on the amino acid value of the aminosilicone oil, the mass blending ratio range of 3-isocyanatopropyltrimethoxysilane to aminosilicone oil is 9.5 to 34.1:100.

[0006] In component A, the hydrophobic silica slurry contains 0.5-3% by weight of a wetting dispersant, 40-60% of hydrophobic silica, and 40-60% of an organic solvent. The method for producing the hydrophobic silica slurry is to add the wetting dispersant to half the amount of the organic solvent and mix uniformly, add the hydrophobic silica, stir at a stirring speed of 500-2000 r / min for 30-60 minutes to disperse it uniformly, and then inject the remaining organic solvent into the system and disperse it uniformly. The hydrophobic silica is produced by a gas-phase method, and the organic solvent is one of xylene, acetone, isopropanol, or butyl acetate.

[0007] In component A, the composite wheat straw fiber powder contains, by weight percentage, 25-40% wheat straw fiber powder, 20-40% vinyl silicone oil, 2-4% hydrogen-containing silicone oil, 0.01-0.05% platinum catalyst, and 30-50% xylene. The method for producing the composite wheat straw fiber powder involves mixing xylene and wheat straw fiber powder, ultrasonically dispersing them for 10-30 minutes, adding vinyl silicone oil and hydrogen-containing silicone oil and mixing them uniformly, adding a platinum catalyst, raising the temperature to 120°C-150°C and reacting for 1-5 hours, cooling and filtering the reaction product, drying it at 60-80°C for 24 hours, and then grinding and sieving it. Wheat straw fiber powder is sieved through a 200-500 mesh, and the vinyl group content in the vinyl silicone oil is 0.05-0.8 wt%, the hydrogen content in the hydrogen-containing silicone oil is 1.5-1.8 wt%, and the platinum content range of the platinum catalyst is 1000 ppm-10000 ppm.

[0008] In component A, the organic solvent is one of xylene, acetone, isopropanol, or butyl acetate, and the defoaming agent is a polyether-modified silicone type defoaming agent.

[0009] The aforementioned component A is obtained by the following steps: dispersing urea group-modified aminosilicone oil in an organic solvent, dispersing it at a rotation speed of 300 r / min to 800 r / min for 5 to 20 minutes, and mixing it to achieve uniform dispersion; adding composite wheat straw fiber powder and hydrophobic silica slurry, dispersing it at high speed at a rotation speed of 1500 r / min to 3000 r / min for 60 to 180 minutes, and mixing it to achieve uniform dispersion; and adjusting the stirring speed to 300 r / min to 500 r / min, adding an antifoaming agent, and stirring for 5 to 10 minutes.

[0010] In component B, the silica content in the ethyl orthosilicate is in the range of 28% to 40%.

[0011] In component C, the organotin drying agent includes di-n-butyltin dilaurate, dibutyltin diacetate, or dioctyltin dilaurate.

[0012] The above-mentioned superhydrophobic coating, which has excellent mechanical properties, is used in the field of cured coatings, by uniformly mixing components A and B in a mass ratio of 100:5 to 20, then adding component C in an amount of 0.1% to 0.5% of the mass of component A, stirring uniformly, applying it to the surface of a substrate, drying at room temperature for 24 to 72 hours to form a superhydrophobic cured coating.

[0013] Principle of Invention: The core innovation of this invention lies in the creation of a synergistic system that integrates four elements of superhydrophobic coating: macro-reinforcement, micro-texture, interfacial compatibility, and cross-linking hardening. By precisely controlling the structural design, modification process, and blending ratio of each component, a strong bonding effect is formed between the composite wheat straw fiber powder, the hydrophobic silica slurry, and the urea group-modified aminosilicone oil matrix. This solves the technical challenges of conventional superhydrophobic coatings, such as "easily damaged micro-texture structures" and "incompatibility between reinforcing materials and hydrophobic systems," and also enables the high-value utilization of agricultural waste. The principle is as follows:

[0014] (1) Composite wheat straw fiber powder: Dual-function design of "rod-shaped reinforcing phase + hydrophobic interface": In this invention, the powder is designed as a dual-function unit of "mechanically strengthened + hydrophobic compatibility" through a suitable modification process and parameters, and the principle is as follows: The need for suitable particle size and morphology: The wheat straw fiber powder is limited to a particle size of 200-500 mesh (rod-shaped spectral ratio 5-10:1).

[0015] (2) Hydrophobic silica slurry: Micro-textured units with "high specific surface area + uniform dispersion": The core of superhydrophobic performance lies in "low surface energy + micro-nanometer uneven structure," and in this invention, the formation of a uniform micro-uneven base is ensured by preferably selecting a hydrophobic silica manufacturing method and slurry dispersion process. The principle is as follows: Essential advantages of gas-phase manufacturing: Hydrophobic silica is manufactured by gas-phase method (e.g., Evonik AEROSIL R972), and its specific surface area is 100-200 m². 2 The particle size is 10-20 nm / g, which is far superior to silica produced by precipitation (specific surface area < 80 m²). 2 (The particle size distribution is non-uniform, measured per gram.)

[0016] (3) Urea group-modified aminosilicone oil: A matrix that achieves both "low surface energy + high crosslinking activity": The polymer matrix is ​​the core component that connects the reinforcing phase (wheat straw fiber powder) and the uneven units (silica). In this invention, a balance of "hydrophobic properties, mechanical properties, and interfacial compatibility" is achieved through urea group modification.

[0017] The above structure enables a binding mechanism involving the synergistic action of multiple components, which is specifically as follows:

[0018] Synergistic effect of macro-reinforcement and micro-irregularity: Micron-sized protrusions formed from composite wheat straw fiber powder (25-75 μm) and nanoscale mammary protrusions formed from hydrophobic silica (50-200 nm) create a "micron-nano" double-irregularity structure, thereby satisfying the morphological requirements of superhydrophobicity (water forms a Cassie-Baxter state on the surface, with a contact angle > 150°) and resisting abrasion caused by external forces through the interlocking support of the wheat straw fibers (for example, the fibers bear stress during friction, preventing the detachment of the silica mammary protrusions). If the particle size or modification conditions of the present invention are deviated from (for example, if the particle size of the wheat straw is > 500 mesh or unmodified), an effective hierarchical structure cannot be formed, the irregularity structure is damaged (hydrophobicity is lost), or the reinforcement effect is insufficient (abrasion resistance is lost).

[0019] Synergistic effect of interfacial compatibility and crosslinking hardening: The polysiloxane chains grafted onto the surface of the composite wheat straw fiber powder and the compatible chains of the wetting dispersant in the hydrophobic silica slurry all exhibit good compatibility with the urea group-modified aminosilicone oil matrix, avoiding the conventional coating problem of "interfacial separation of reinforcing material and hydrophobic matrix." Furthermore, a "physicochemical double crosslink" is formed by ureid group hydrogen bonds and Si-O-Si chemical crosslinking bonds in the matrix, resulting in the tight bonding and integration of the three components. The coating possesses excellent flexibility (no cracks when bent 1 mm, GB / T 1731-1993) and high adhesion (Grade 0, GB / T 9286-1998).

[0020] The synergistic relationship between curing conditions and performance: Limiting the mass ratio of components A / B to 100:5-20 and the amount of component C added to 0.1%-0.5% is key to achieving both curing speed and coating performance. If component B (ethyl orthosilicate) is too little (<5%), the crosslinking density will be insufficient, reducing mechanical properties and corrosion resistance. If it is too much (>20%), the curing shrinkage rate will increase, making the coating more prone to cracking. If the amount of component C (organotin desiccant) used is too little, the curing time will be too long (>72h), and if it is too much, the curing will be too fast, causing stress defects inside the coating. By drying at room temperature for 24-72 hours or curing while heating at 60°C for 6 hours, sufficient progress of the crosslinking reaction is ensured, while avoiding the decomposition of the wheat straw fiber modified layer and the aggregation of silica due to high temperatures. [Effects of the Invention]

[0021] Beneficial Effects: Compared to conventional technology, the present invention has the following remarkable advantages: (1) High balance of superhydrophobic performance and mechanical properties: The water contact angle of the obtained coating reaches 150° or more, and abrasion resistance is greatly improved (abrasion resistance is improved by more than 30%), and adhesion reaches grade 0 (GB / T 9286-1998), thereby solving the technical problems of conventional superhydrophobic coatings, such as reduced mechanical properties and easy deterioration. (2) Multifunctional synergistic effect: The synergistic effect of composite wheat straw fiber powder and hydrophobic silica not only improves the mechanical properties of the coating but also strengthens the corrosion resistance and self-cleaning properties of the coating. In a salt spray test (ASTM B117), the coating did not exhibit foaming or deterioration even after 500 hours, showing significant superiority over conventional superhydrophobic coatings. (3) High value-added utilization of agricultural waste: By manufacturing composite wheat straw fiber powder using wheat straw as a raw material, high value-added utilization of agricultural waste is realized, reducing the production cost of paint and conforming to the concept of green and sustainable development. (4) Simplicity and feasibility of the manufacturing process: The manufacturing process flow is clear, raw materials are readily available, and no special equipment is required, making it suitable for industrial production. In addition, the paint has good storage stability and can be stored at room temperature for more than 3 months. [Brief explanation of the drawing]

[0022] [Figure 1] This is an image obtained by observing the composite wheat straw fiber powder produced in Example 1 with a field emission scanning electron microscope. [Figure 2] This is an image obtained by observing the surface morphology of the coating of the superhydrophobic paint having excellent mechanical properties produced in Example 1 with a field emission scanning electron microscope. [Figure 3] This is an image obtained by observing the surface morphology of the coating produced in Comparative Example 1 with a field emission scanning electron microscope. [Figure 4] This is a diagram showing the contact angle of the cured coating produced in Example 1. [Figure 5] This is a diagram showing the contact angle of the cured coating produced in Comparative Example 1.

Modes for Carrying Out the Invention

[0023] Hereinafter, the technical solution of the present invention will be further described together with examples. All the test materials used in the examples can be purchased through normal routes.

[0024] Example 1 The superhydrophobic paint having excellent mechanical properties of the present invention included the following components.

[0025] Component A: 35 g of urea group-modified amino silicone oil, 25 of hydrophobic silica slurry, 1 g of composite wheat straw fiber powder, 10 g of organic solvent (xylene), 0.1 g of defoaming agent (polyether-modified silicone type, specifically, BYK024 manufactured by BYK Chemical Co., Ltd.) Component B: Ethyl orthosilicate (silica (SiO2) content 28%) Component C: Organotin desiccant (di-n-butyltin dilaurate).

[0026] The method for producing urea-modified aminosilicone oil was as follows: 100 g of aminosilicone oil (amino acid value 0.8 mmol / g) and 17.2 g of 3-isocyanatopropyltrimethoxysilane were weighed. The mixture was carried out in an anhydrous, oxygen-free environment and reacted at 50°C for 8 hours to obtain the product.

[0027] The materials used to produce the hydrophobic silica slurry were 0.5 g of a wetting and dispersing agent (the active ingredient being a polyether-modified polysiloxane, specifically BYK333 from BYK Chemical), 40 g of hydrophobic silica (produced by a gas-phase method, specifically AEROSIL R972 from Evonik), and 40 g of an organic solvent (xylene). The production method was as follows: The wetting and dispersing agent was added to 20 g of the organic solvent and mixed uniformly, the hydrophobic silica was added and stirred at 500 r / min for 60 min, and finally the remaining 20 g of the organic solvent was added and dispersed uniformly to obtain the slurry.

[0028] The materials used to produce the composite wheat straw fiber powder were 25g of wheat straw fiber powder (passing through a 200-mesh sieve), 20g of vinyl silicone oil (vinyl group content 0.05 wt%), 2g of hydrogen-containing silicone oil (hydrogen content 1.5 wt%), 0.01g of platinum catalyst (platinum content 1000 ppm), and 30g of xylene. The production method was as follows: xylene was added to the reaction system, wheat straw fiber powder was added and ultrasonically dispersed for 10 minutes, vinyl silicone oil and hydrogen-containing silicone oil were added and mixed uniformly, platinum catalyst was added, the temperature was raised to 120°C and the reaction was carried out for 5 hours, cooled, filtered, dried at 60°C for 24 hours, pulverized, and sieved through a 200-mesh sieve to obtain the product.

[0029] The method for producing component A was as follows: Urea group-modified aminosilicone oil was dispersed in the organic solvent xylene and dispersed at 300 r / min for 20 minutes. Compound wheat straw fiber powder and hydrophobic silica slurry were added and dispersed at 1500 r / min for 180 minutes. The stirring speed was then adjusted to 300 r / min, an antifoaming agent was added, and the mixture was stirred for 5 minutes to obtain component A.

[0030] A cured coating was manufactured using the above-mentioned superhydrophobic paint, which has excellent mechanical properties: Components A and B were uniformly mixed in a mass ratio of 100:5, component C (0.1% of the mass of component A) was added, and after uniform stirring, the mixture was applied to the surface of a metal substrate and dried at room temperature for 24 hours to form a superhydrophobic cured coating.

[0031] As shown in Figure 1, the composite wheat straw fiber powder produced in Example 1 was observed using a field emission scanning electron microscope. The vinyl silicone oil and hydrogen-containing silicone oil were effectively deposited and modified on the surface of the powder, imparting hydrophobicity and promoting the effective dispersion of hydrophobic SiO2 in the coating. They interact with each other to exhibit functions similar to reinforced concrete.

[0032] As shown in Figure 2, this is an image of the surface morphology of the superhydrophobic coating with excellent mechanical properties manufactured in Example 1, observed with a field emission scanning electron microscope. The composite wheat straw fiber powder and hydrophobic SiO2 powder formed an effective micro-masthia-like protrusion morphology on the coating surface. The inherent hydrophobic properties of the filler (selection of hydrophobic SiO2 and modification of the wheat straw powder by coating with low surface tension silicone oil) and the biomimetic design imparted a lotus leaf effect to the coating, thereby achieving the superhydrophobic performance of the coating.

[0033] Example 2 The superhydrophobic coating having excellent mechanical properties according to the present invention comprises the following compositional components.

[0034] Component A: 40g urea group-modified aminosilicone oil, 30g hydrophobic silica slurry, 3g composite wheat straw fiber powder, 15g organic solvent (isopropanol), 0.5g defoaming agent (polyether-modified silicone type, specifically BYK1790 manufactured by BYK Chemical), Component B: Ethyl orthosilicate (32% silica (SiO2) content), Component C: Organotin desiccant (dibutyltin diacetate).

[0035] The method for producing urea-modified aminosilicone oil was as follows: 100 g of aminosilicone oil (amino acid value 1.2 mmol / g) and 25.8 g of 3-isocyanatopropyltrimethoxysilane were weighed. The mixture was carried out in an anhydrous, oxygen-free environment and reacted at 60°C for 12 hours to obtain the product.

[0036] The materials used to produce the hydrophobic silica slurry were 1.5 g of wetting dispersant (the active ingredient being a polyether-modified polysiloxane, specifically TEGO Wet270 from Evonik), 50 g of hydrophobic silica (produced by a gas-phase method, specifically AEROSIL R974 from Evonik), and 40 g of organic solvent (acetone). The production method was as follows: The wetting dispersant was added to 25 g of organic solvent and mixed uniformly, the hydrophobic silica was added, the stirring speed was adjusted to 800 r / min, and the mixture was stirred for 50 min to ensure thorough and uniform dispersion, and finally the remaining 25 g of organic solvent was added to the system and dispersed uniformly to obtain the slurry.

[0037] The materials used to produce the composite wheat straw fiber powder were 30g of wheat straw fiber powder (passing through a 300-mesh sieve), 30g of vinyl silicone oil (vinyl group content 0.4 wt%), 3g of hydrogen-containing silicone oil (hydrogen content 1.6 wt%), 0.02g of platinum catalyst (platinum content 3000 ppm), and 35g of xylene. The production method was as follows: Xylene was added to the reaction system, wheat straw fiber powder was added, and ultrasonic dispersion was performed for 15 minutes to promote effective dispersion of the wheat straw fiber powder in the xylene. The vinyl silicone oil and hydrogen-containing silicone oil were added to the system mixed and dispersed in step 1, and mixed uniformly. The platinum catalyst was added, the temperature was raised to 130°C, and the reaction was carried out for 4 hours. After the reaction, the mixture was cooled, filtered, dried at 65°C for 24 hours, and pulverized. Finally, it was sieved through a 200-mesh sieve to obtain the product.

[0038] The method for producing component A was as follows: Urea group-modified aminosilicone oil was dispersed in the organic solvent isopropanol and dispersed at a rotation speed of 500 r / min for 15 minutes. Compound wheat straw fiber powder and hydrophobic silica slurry were added and dispersed at a high speed of 1800 r / min for 150 minutes, then mixed uniformly. The stirring speed was then adjusted to 400 r / min, an antifoaming agent was added, and the mixture was stirred for 6 minutes to obtain component A.

[0039] A cured coating was manufactured using the above-mentioned superhydrophobic paint, which has excellent mechanical properties: Components A and B were uniformly mixed in a mass ratio of 100:10, component C (0.3% of the mass of component A) was added, and after uniform stirring, the mixture was applied to the surface of a metal substrate and dried at room temperature for 48 hours to form a superhydrophobic cured coating.

[0040] Example 3 The superhydrophobic coating having excellent mechanical properties according to the present invention comprises the following compositional components.

[0041] Component A: 45g urea group-modified aminosilicone oil, 35g hydrophobic silica slurry, 4g composite wheat straw fiber powder, 20g organic solvent (butyl acetate), 0.8g defoaming agent (polyether-modified silicone type, specifically BYK1790 manufactured by BYK Chemical), Component B: Ethyl orthosilicate (32% silica (SiO2) content), Component C: Organotin desiccant (dioctyltin dilaurate).

[0042] The method for producing urea-modified aminosilicone oil was as follows: 100 g of aminosilicone oil (amino acid value 1.8 mmol / g) and 34.1 g of 3-isocyanatopropyltrimethoxysilane were weighed. The mixture was carried out in an anhydrous, oxygen-free environment and reacted at 65°C for 16 hours to obtain the product.

[0043] The materials used to produce the hydrophobic silica slurry were 2.5 g of a wetting and dispersing agent (the active ingredient being a polyether-modified polysiloxane, specifically TEGO Dispers 655 from Evonik), 55 g of hydrophobic silica (produced by a gas-phase method, specifically AEROSIL R972 from Evonik), and 45 g of an organic solvent (butyl acetate). The production method was as follows: 22.5 g of the wetting and dispersing agent was added to the organic solvent and mixed uniformly. Hydrophobic silica was added to the mixture, the stirring speed was adjusted to 1000 r / min, and the mixture was stirred for 45 minutes to ensure thorough and uniform dispersion. Finally, the remaining 25 g of the organic solvent was added and dispersed uniformly to obtain the slurry.

[0044] The materials used to produce the composite wheat straw fiber powder were 35g of wheat straw fiber powder (passing through a 400-mesh sieve), 35g of vinyl silicone oil (vinyl group content 0.6 wt%), 3.5g of hydrogen-containing silicone oil (hydrogen content 1.7 wt%), 0.03g of platinum catalyst (platinum content 5000 ppm), and 40g of xylene. The production method was as follows: Xylene was added to the reaction system, and the wheat straw fiber powder was added and ultrasonically dispersed for 20 minutes to promote effective dispersion of the wheat straw fiber powder in the xylene. This was then added to a system containing a mixture of vinyl silicone oil and hydrogen-containing silicone oil and mixed uniformly. After adding the platinum catalyst, the temperature was raised to 130°C and the reaction was carried out for 3 hours. The reaction product was cooled, filtered, dried at 75°C for 24 hours, and then pulverized. Finally, it was sieved through a 200-mesh sieve to obtain the product.

[0045] The method for producing component A was as follows: Urea group-modified aminosilicone oil was dispersed in butyl acetate organic solvent, dispersed at a rotation speed of 600 r / min for 10 minutes, composite wheat straw fiber powder and hydrophobic silica slurry were added, and the mixture was dispersed at a high speed of 1500 r / min for 120 minutes, then uniformly mixed, and the stirring speed was adjusted to 450 r / min, an antifoaming agent was added, and the mixture was stirred for 7 minutes to obtain component A.

[0046] A cured coating was manufactured using the above-mentioned superhydrophobic paint, which has excellent mechanical properties: Components A and B (ethyl orthosilicate, silica (SiO2) content 32%) were uniformly mixed in a mass ratio of 100:15, component C (dioctyl tin dilaurate, 0.4% of the mass of component A) was added, and after uniform stirring, the mixture was applied to the surface of a metal substrate and dried at room temperature for 72 hours to form a superhydrophobic cured coating.

[0047] Example 4 The superhydrophobic coating having excellent mechanical properties according to the present invention comprises the following compositional components.

[0048] Component A: 35g urea-modified aminosilicone oil, 25g hydrophobic silica slurry, 1g composite wheat straw fiber powder, 10g organic solvent (acetone), 0.1g defoaming agent (polyether-modified silicone type, specifically TEGO Foamex 812 manufactured by TEGO), Component B: Ethyl orthosilicate (silica (SiO2) content 40%) Component C: Organotin desiccant (di-n-butyltin dilaurate).

[0049] The method for producing urea-modified aminosilicone oil was as follows: 100 g of aminosilicone oil (amino acid value 0.5 mmol / g) and 9.5 g of 3-isocyanatopropyltrimethoxysilane were weighed, mixed in an anhydrous, oxygen-free environment, and reacted at 70°C for 24 hours to obtain the product.

[0050] The materials used to produce the hydrophobic silica slurry were 0.5 g of a wetting and dispersing agent (the active ingredient being a polyether-modified polysiloxane, specifically TEGO Dispers 655 from Evonik), 40 g of hydrophobic silica (produced by a gas-phase method, specifically HDK H18 from Wacker), and 60 g of an organic solvent (acetone). The production method was as follows: 30 g of the wetting and dispersing agent was added to the organic solvent and mixed uniformly, the hydrophobic silica was added, the mixture was stirred at 2000 r / min for 30 min, and finally the remaining 30 g of organic solvent was added and dispersed uniformly to obtain the slurry.

[0051] The materials used to produce the composite wheat straw fiber powder were 25g of wheat straw fiber powder (passing through a 200-mesh sieve), 20g of vinyl silicone oil (vinyl group content 0.05 wt%), 2g of hydrogen-containing silicone oil (hydrogen content 1.5 wt%), 0.01g of platinum catalyst (platinum content 1000 ppm), and 30g of xylene. The production method was as follows: Xylene was added to the reaction system, the wheat straw fiber powder was added, and ultrasonic dispersion was performed for 30 minutes to promote effective dispersion of the wheat straw fiber powder in the xylene. This was then added to a system in which vinyl silicone oil and hydrogen-containing silicone oil were mixed and dispersed, and mixed uniformly. The platinum catalyst was added, the temperature was raised to 150°C, and the reaction was carried out for 1 hour. The reaction product was cooled, filtered, dried at 80°C for 24 hours, pulverized, and sieved through a 200-mesh sieve to obtain the product.

[0052] The method for producing component A was as follows: Urea group-modified aminosilicone oil was dispersed in an organic solvent, dispersed at a rotation speed of 600 r / min for 7 minutes, mixed and uniformly dispersed, and then composite wheat straw fiber powder and hydrophobic silica slurry were added and dispersed at a high speed of 2500 r / min for 80 minutes and uniformly mixed. Finally, the stirring speed was adjusted to 400 r / min, an antifoaming agent was added, and the mixture was stirred for 6 minutes to obtain the component A.

[0053] A cured coating was manufactured using the above-mentioned superhydrophobic paint, which has excellent mechanical properties: Components A and B (ethyl orthosilicate, silica (SiO2) content 40%) were uniformly mixed in a mass ratio of 100:20, component C (0.5% of the mass of component A) was added, and after uniform stirring, the mixture was applied to the surface of a metal substrate and dried at room temperature for 60 hours to form a superhydrophobic cured coating.

[0054] Example 5 The superhydrophobic coating having excellent mechanical properties according to the present invention comprises the following compositional components.

[0055] Component A: 50g urea group-modified aminosilicone oil, 40g hydrophobic silica slurry, 5g composite wheat straw fiber powder, 25g organic solvent (xylene), 1.0g defoaming agent (polyether-modified silicone type, specifically Defom 5300 manufactured by Elementis), Component B: Ethyl orthosilicate (silica (SiO2) content 40%) Component C: Organotin desiccant (dibutyltin diacetate).

[0056] The method for producing urea-modified aminosilicone oil was as follows: 100 g of aminosilicone oil (amino acid value 1.8 mmol / g) and 37 g of 3-isocyanatopropyltrimethoxysilane were weighed, mixed in an anhydrous, oxygen-free environment, and reacted at 70°C for 20 hours to obtain the product.

[0057] The materials used to produce the hydrophobic silica slurry were 3.0 g of a wetting dispersant (the active ingredient being a polyether-modified polysiloxane, specifically TEGO Dispers 655 from Evonik), 60 g of hydrophobic silica (produced by a gas-phase method, specifically AEROSIL R974 from Evonik), and 40 g of an organic solvent (xylene). The production method was as follows: 20 g of the wetting dispersant was added to the organic solvent and mixed uniformly, the hydrophobic silica was added, the stirring speed was adjusted to 1500 r / min, and the mixture was stirred for 40 min to ensure thorough and uniform dispersion, and finally the remaining 20 g of organic solvent was added to the system and dispersed uniformly to obtain the slurry.

[0058] The materials used to produce the composite wheat straw fiber powder were 40g of wheat straw fiber powder (passing through a 500-mesh sieve), 40g of vinyl silicone oil (vinyl group content 0.8 wt%), 4g of hydrogen-containing silicone oil (hydrogen content 1.8 wt%), 0.05g of platinum catalyst (platinum content 10,000 ppm), and 50g of xylene. The production method was as follows: Xylene was added to the reaction system, the wheat straw fiber powder was added, and ultrasonic dispersion was carried out for 25 minutes to promote effective dispersion of the wheat straw fiber powder in the xylene. This was then added to a system in which vinyl silicone oil and hydrogen-containing silicone oil were mixed and dispersed, and mixed uniformly. After adding the platinum catalyst, the temperature was raised to 140°C and the reaction was carried out for 4 hours. The reaction product was cooled and filtered, then dried at 75°C for 24 hours and pulverized, and finally sieved through a 200-mesh sieve to obtain the product.

[0059] The method for producing component A was as follows: Urea group-modified aminosilicone oil was dispersed in an organic solvent, dispersed at a rotation speed of 800 r / min for 5 minutes, mixed and uniformly dispersed, and then composite wheat straw fiber powder and hydrophobic silica slurry were added and dispersed at a high speed of 3000 r / min for 60 minutes and uniformly mixed. Finally, the stirring speed was adjusted to 300 r / min, an antifoaming agent was added, and the mixture was stirred for 10 minutes to obtain the component A.

[0060] A cured coating was manufactured using the above-mentioned superhydrophobic paint, which has excellent mechanical properties: Components A and B were uniformly mixed in a mass ratio of 100:5, component C (0.1% of the mass of component A) was added, and after uniform stirring, the mixture was applied to the surface of a metal substrate and dried at room temperature for 48 hours to form a superhydrophobic cured coating.

[0061] Comparative Example 1 Compared to Example 1, the composite coating contained only urea-modified aminosilicone oil as component A, ethyl orthosilicate (silica (SiO2) content 28%) as component B, and an organotin drying agent (di-n-butyltin dilaurate) as component C.

[0062] A coating was manufactured using the above-mentioned paint: Components A and B were uniformly mixed in a mass ratio of 100:5, component C (0.1% of the mass of component A) was added, and after uniform stirring, the mixture was applied to the surface of a metal substrate and dried at room temperature for 24 hours to form a coating. Figure 3 shows an image of the surface morphology of the coating manufactured in Comparative Example 1, observed with a field emission scanning electron microscope. It is uniform and flat, and the superhydrophobic properties of the coating have not been achieved. Figure 4 shows the contact angle of the cured coating manufactured in Example 1, indicating the superhydrophobic properties of the coating. Figure 5 shows the contact angle of the cured coating manufactured in Comparative Example 1. The value of its hydrophobic angle is much lower than that of the coating manufactured in the present invention, and the superhydrophobic effect cannot be achieved.

[0063] [Table 1] TIFF2026102896000003.tif76170

[0064] As shown in Table 1, Examples 1-5 demonstrate that the coatings possess excellent mechanical properties (including hardness, flexibility, coating cross-cut adhesion, and impact resistance) and are applicable to practical use. Furthermore, the coatings exhibit excellent superhydrophobic properties, further ensuring the coating's salt spray resistance and heat and humidity resistance.

[0065] Dual-function design of composite wheat straw fiber powder with "rod-shaped reinforcing phase + hydrophobic interface": If the particle size is smaller than 200 mesh (too coarse), the flatness of the coating surface is destroyed, and water accumulates on the coating surface (increased roll angle). If it is larger than 500 mesh (too fine), an effective "macro-support skeleton" cannot be formed, and the mechanical reinforcing effect is reduced (pencil hardness is lower than H, and the improvement rate of wear resistance is less than 20%). The rod-shaped structure of 200-500 mesh forms an interlocking support network similar to "rebar" in the coating, which can directly improve the impact resistance (passes GB / T 1732-1993 forward / reverse impact) and wear resistance (improvement of more than 30%) of the coating. The necessity of the suitable modification system: An addition reaction system of "vinyl silicone oil (vinyl group content 0.05-0.8 wt%) + hydrogen-containing silicone oil (hydrogen content 1.5-1.8 wt%) + platinum catalyst (1000-10000 ppm)" is adopted and the reaction is carried out at 120-150°C for 1-5 hours. The core of this modification is to graft "polysiloxane chains by Si-C bonds" onto the surface of the wheat straw fibers. Due to the low surface energy of polysiloxane (surface tension 20-25 mN / m), the wheat straw fiber powder changes from hydrophilic (water contact angle <60°) to hydrophobic (water contact angle >120°), preventing the destruction of the coating's hydrophilic system due to water absorption and aggregation. Furthermore, the addition reaction between vinyl groups and hydrogen-containing silicone oil is irreversible, resulting in a strong bond between the modified layer and the fiber surface, which is far superior to physical coating (e.g., direct immersion in silicone oil), and allows for sustained hydrophobicity during the coating wear process. Precise control of catalyst and reaction temperature: The platinum catalyst content is limited to 1000-10000 ppm. Below 1000 ppm, the addition reaction conversion rate is lower than 60%, resulting in insufficient hydrophobic groups on the fiber surface and making interfacial separation with the hydrophilic matrix or curing agent more likely. Above 10000 ppm, the reaction rate is too fast, causing polysiloxane chains to aggregate on the fiber surface, forming localized highly hydrophobic regions and destroying the microroughness uniformity of the coating.A reaction temperature of 120-150°C balances reaction rate and fiber stability: below 120°C, the reaction is incomplete, and above 150°C, the wheat straw fibers undergo thermal decomposition (cellulose decomposition temperature is approximately 160°C), resulting in a loss of mechanical strengthening ability.

[0066] The hydrophobic silica slurry exhibits "high specific surface area + uniform dispersion": The high specific surface area forms densely packed "nano-mammary protrusions" on the coating surface, which, together with the "micron-grade rod-shaped protrusions" of the composite wheat straw fiber powder, form a "micron-nano" hierarchical uneven structure (shown in Figure 2). This is key to achieving a water contact angle >150° and a roll angle <9° (compared to Comparative Example 1, without silica addition, only a flat surface is formed, and the contact angle is only 105°). Precise limitation of the slurry dispersion process: The production of the hydrophobic silica slurry requires "adding a wetting dispersant to half the amount of organic solvent, adding hydrophobic silica, stirring at a stirring speed of 500-2000 r / min for 30-60 min, and finally injecting the remaining organic solvent into the system." The core of this multi-step dispersion process is to avoid aggregation of nanosilica. If silica is added directly to the entire amount of organic solvent, hard aggregation (particle size >1 μm) is formed due to hydrogen bonding of surface hydroxyl groups, preventing the formation of effective micro-irregularities. A stirring speed of 500-2000 r / min is suitable for a time of 30-60 min, adjusting the dispersed silica particle size to 50-200 nm, which forms a hierarchical structure with the wheat straw fiber powder (200-500 mesh, i.e., 25-75 μm). Furthermore, a polyether-modified polysiloxane (e.g., BYK333) is selected as the wetting dispersant. Its molecular chains are bonded to the silica surface hydroxyl groups at one end and compatible with organic solvents and the polymer matrix at the other end, further suppressing aggregation and ensuring the long-term stability of the microstructure.

[0067] Dual action of urea group modification: Urea group-modified aminosilicone oil is obtained by reacting 3-isocyanatopropyltrimethoxysilane (IPTS) with aminosilicone oil having an amino acid value of 0.5-1.8 mmol / g. The isocyanate group (-NCO) of IPTS reacts with the amino group (-NH2) of the aminosilicone oil to generate a ureid group (-NH-CO-NH-), and hydrogen bonding in the ureid group forms physical crosslinking points, improving the cohesive force of the matrix, resulting in a pencil hardness of 2H-3H for the coating (the hardness of the unmodified aminosilicone oil matrix is ​​only B grade). Furthermore, the methoxysilyl groups (-OCH3) provided by IPTS undergo a condensation reaction with silicon hydroxyl groups (-SiOH) generated by the hydrolysis of the curing agent ethyl orthosilicate, forming Si-O-Si chemical crosslinks. This creates a dense three-dimensional network structure that firmly fixes the composite wheat straw fiber powder and hydrophobic silica within the matrix, preventing detachment due to external forces (this is key to improving coating abrasion resistance by more than 30% and achieving salt spray resistance >500h). Strict limitation of amino acid value range: The amino acid value of the amino silicone oil is limited to 0.5-1.8 mmol / g. If the amino acid value is too low (<0.5 mmol / g), there will be insufficient reaction sites with IPTS, resulting in a low ureid group content, insufficient matrix crosslinking density, and inferior mechanical properties. If the amino acid content is too high (>1.8 mmol / g), the excess amino groups form hydrogen bonds with the hydroxyl groups on the silica surface, causing silica aggregation and disrupting the micro-rough structure. Furthermore, residual amino groups increase the matrix surface energy, reducing the water contact angle to below 130° and resulting in a loss of superhydrophobicity. To avoid hydrolysis and loss of IPTS due to moisture and to ensure modification efficiency, the modification reaction must be carried out in an anhydrous, oxygen-free environment at 50-70°C for 8-24 hours.

[0068] The core contradiction of conventional technology lies in the fact that "superhydrophobic performance depends on the micro-rough structure, while mechanical reinforcement requires the addition of rigid materials, and the two mutually destructively destroy each other." Adding only nanoparticles (e.g., hydrophobic silica) results in poor abrasion resistance of the coating. Alternatively, adding unmodified reinforcing materials (e.g., ordinary fibers) destroys the micro-rough structure, rendering the hydrophobic performance ineffective. This invention fundamentally resolves this contradiction through the synergistic combination of the following preferred conditions: When the composite wheat straw fiber powder satisfies the conditions of "200-500 mesh particle size + modification with vinyl silicone oil / hydrogen-containing silicone oil + reaction at 120-150°C", it simultaneously achieves "macro-reinforcement" and "hydrophobic compatibility" while avoiding destruction of the microstructure. When the hydrophobic silica employs a "vapor phase manufacturing method + multi-step dispersion process", it forms uniform nano-rough units that synergize with the micron structure of the wheat straw fibers. Only when the polymer matrix is ​​"modified with amino silicone oil with an amino acid value of 0.5-1.8 mmol / g + IPTS" can it achieve both "low surface energy" and "high crosslinking activity," realizing interfacial fusion and strong fixation of each component. If any one of the above preferred conditions is deviated, the technical effect will be significantly reduced. For example, if wheat straw fiber powder is left unmodified (comparative example extension), silica aggregates around it due to its surface hydrophilicity, reducing the coating contact angle to 120° or less, and improving abrasion resistance by less than 10%. If hydrophobic silica is processed using a precipitation method (comparative example extension), the specific surface area is insufficient, preventing the formation of effective micro-irregularities, and the contact angle is <140°. If the amino silicone oil has an amino acid value of >1.8 mmol / g (comparative example extension), the residual amino groups increase the surface energy, resulting in a roll angle >30° and loss of superhydrophobicity.

[0069] In summary, the present invention constructs an integrated system of "macro-micro synergistic strengthening, interfacial compatibility, and crosslinking hardening" by precisely defining the structure, modification process, blending ratio, and curing conditions of each component. This achieves excellent performance with a water contact angle > 150°, improved abrasion resistance by more than 30%, and adhesion of grade 0, while also enabling high value-added utilization of wheat straw, an agricultural waste product, and demonstrating high potential for future applications.

Claims

1. A superhydrophobic coating having excellent mechanical properties, manufactured by synergistically combining components A, B, and C, with the following weight percentages: Component A consists of 35% to 50% urea-modified aminosilicone oil, 25% to 40% hydrophobic silica slurry, 1% to 5% composite wheat straw fiber powder, 10% to 25% organic solvent, and 0.1% to 1% defoaming agent. The urea-modified aminosilicone oil is produced by reacting 3-isocyanatopropyltrimethoxysilane with an aminosilicone oil having an amino acid value of 0.5 to 1.8 mmol / g under anhydrous and oxygen-free conditions at 50°C to 70°C for 8 to 24 hours; the composite wheat straw fiber powder is produced by modifying wheat straw fiber powder with vinyl silicone oil, hydrogen-containing silicone oil, and a platinum catalyst; and the hydrophobic silica slurry is produced by dispersing hydrophobic silica produced by a gas-phase method in an organic solvent with a wetting dispersant. Component B is ethyl orthosilicate, a hardening agent with a silica content of 28% to 40%. A superhydrophobic paint with excellent mechanical properties, characterized in that component C is an organotin drying agent.

2. The superhydrophobic coating having excellent mechanical properties according to claim 1, characterized in that, in the production of urea group-modified aminosilicone oil, the range of the mass blending ratio of 3-isocyanatopropyltrimethoxysilane to aminosilicone oil is 9.5 to 34.1:100, depending on the amino value of the aminosilicone oil.

3. In component A, the hydrophobic silica slurry contains, by weight percentage, 0.5 to 3% wetting dispersant, 40 to 60% hydrophobic silica, and 40 to 60% organic solvent. The method for producing a hydrophobic silica slurry is to add a wetting dispersant to half the amount of organic solvent and mix uniformly, add hydrophobic silica, stir at a stirring speed of 500 to 2000 r / min for 30 to 60 min to thoroughly and uniformly disperse, and then inject the remaining organic solvent into the system and disperse uniformly, thereby obtaining the superhydrophobic paint having excellent mechanical properties as described in claim 1.

4. The superhydrophobic paint having excellent mechanical properties according to claim 3, characterized in that the hydrophobic silica is produced by a gas-phase method and the organic solvent is one of xylene, acetone, isopropanol, or butyl acetate.

5. In component A, the composite wheat straw fiber powder contains, by weight percentage, 25-40% wheat straw fiber powder, 20-40% vinyl silicone oil, 2-4% hydrogen-containing silicone oil, 0.01-0.05% platinum catalyst, and 30-50% xylene. The method for producing the composite wheat straw fiber powder is to mix xylene and wheat straw fiber powder, ultrasonically disperse them for 10 to 30 minutes, add vinyl silicone oil and hydrogen-containing silicone oil and mix them uniformly, add a platinum catalyst, raise the temperature to 120°C to 150°C and react for 1 to 5 hours, cool and filter the reaction product, dry it at 60 to 80°C for 24 hours, and then grind and sieve it to obtain the superhydrophobic coating having excellent mechanical properties as described in claim 1.

6. The superhydrophobic coating having excellent mechanical properties according to claim 5, characterized in that wheat straw fiber powder is sieved through a 200-500 mesh, the vinyl group content in the vinyl silicone oil is 0.05-0.8 wt%, the hydrogen content of the hydrogen-containing silicone oil is 1.5-1.8 wt%, and the platinum content range of the platinum catalyst is 1000 ppm to 10000 ppm.

7. The superhydrophobic paint having excellent mechanical properties as described in claim 1, characterized in that, in component A, the organic solvent is one of xylene, acetone, isopropanol, or butyl acetate, and the defoaming agent is a polyether-modified silicone type defoaming agent.

8. Component A is, The process involves dispersing urea group-modified aminosilicone oil in an organic solvent, dispersing it at a rotational speed of 300 r / min to 800 r / min for 5 to 20 minutes, and then mixing and dispersing it uniformly. The process involves adding a composite wheat straw fiber powder and a hydrophobic silica slurry, then dispersing them at high speed for 60 to 180 minutes at a rotational speed of 1500 r / min to 3000 r / min, and mixing them uniformly. The superhydrophobic paint having excellent mechanical properties according to claim 1, characterized by being obtained by the steps of adjusting the stirring speed to 300 r / min to 500 r / min, adding an antifoaming agent, and stirring for 5 to 10 min.

9. In component B, the silica content in the ethyl orthosilicate is in the range of 28% to 40%. The superhydrophobic coating having excellent mechanical properties according to claim 1, characterized in that, in component C, the organotin drying agent includes di-n-butyltin dilaurate, dibutyltin diacetate, or dioctyltin dilaurate.

10. An application of the superhydrophobic coating having excellent mechanical properties as described in claim 1 in the field of cured coatings, The application is characterized by uniformly mixing component A and component B in a mass ratio of 100:5 to 20, then adding component C in an amount of 0.1% to 0.5% of the mass of component A, stirring uniformly, applying it to the surface of a substrate, drying at room temperature for 24 to 72 hours, and forming a superhydrophobic cured coating.

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