Preparation method of fluorine-free hydrophobic wear-resistant coating based on organosilane crosslinking

Abstract

The invention discloses a preparation method of a fluorine-free hydrophobic wear-resistant coating based on organosilane crosslinking, and belongs to the technical field of hydrophobic wear-resistant coating preparation, and the preparation method is based on a crosslinking structure generated by a hydrosilylation reaction between two organosilanes. Comprising the following steps: 1, carrying out efficient decontamination and surface activation on a glass substrate by using an organic solvent and an ultraviolet ozone cleaning machine; step 2, dissolving polydimethylsiloxane (PDMS) and poly (dimethylsiloxane-co-methylhydrosiloxane) (PMHS) into ethyl acetate, so as to prepare a spraying solution; and 3, a glass substrate is coated with the prepared spraying liquid through a spraying gun, after curing, a PDMS-PMHS hydrophobic coating is obtained, the hydrophobic wear-resistant coating is obtained, the coating is not limited to preparation of the glass surface, can also be prepared on the surfaces of copper sheets, aluminum sheets, stainless steel, ceramics, plastics and the like, and all can show good hydrophobic wear-resistant performance. The coating has good mechanical property, hydrophobicity, adhesive force, chemical stability and corrosion resistance. The preparation method of the hydrophobic wear-resistant coating is simple, can be used for large-scale preparation and has wide application.

Description

Technical Field

[0001] The present invention belongs to the field of coating material preparation, and specifically is a method for preparing a fluorine-free hydrophobic wear-resistant coating based on organic silane cross-linking Background Art In the field of modern materials science and engineering, coating materials with excellent wear resistance, hydrophobicity and anti-pollution properties are widely used on glass surfaces. As a common engineering material, the improvement of the surface properties of glass is of great significance to enhancing its application effect in many fields, especially in display technology, optical devices, building windows, solar cells, automotive glass and other fields. Traditional glass surface coatings mainly rely on inorganic coatings, polymer coatings and fluoride coatings, among which fluoride coatings have received widespread attention due to their excellent hydrophobicity. However, fluoride coatings have certain limitations in terms of environmental friendliness, wear resistance and processing costs, especially because their fluorine-containing components may have adverse effects on the environment and human health.

[0002] In order to overcome these problems, many researchers have begun to explore fluorine-free coating materials in recent years, especially coatings based on polydimethylsiloxane (PDMS). PDMS, as a commonly used silicone material, has become a popular choice in coating research due to its excellent hydrophobicity, good temperature resistance and chemical resistance.

[0003] Patent document CN202410318777.6 discloses a method for preparing a fluorine-free hydrophobic transparent coating, which can be sprayed, brushed, rolled, etc. to evenly coat a transparent film on the smooth surface of glass, plastic film, or metal, so that it has the beneficial effects of aesthetics and functionality. The coating is mainly prepared by cross-linking ethylene glycol butyl ether (EGBE) and hydroxyl-terminated polydimethylsiloxane (H-PDMS), but the hydrophobic transparent coating is easily damaged in harsh environments, has poor wear resistance, and has a complex preparation process and high cost; Patent document CN202310332347.5 discloses a method for preparing a wear-resistant super-hydrophobic coating, wherein a coating liquid and a primer liquid are prepared separately; the preparation of the coating liquid is specifically as follows: PDMS and hydrophobic SiO2 nanoparticles are blended in ethyl acetate to obtain a PDMS / SiO2 suspension, and an α-cyanoacrylate adhesive is added to the PDMS / SiO2 suspension and ultrasonicated in an ice bath to obtain a coating liquid, but the preparation method is complicated and has unstable super-hydrophobic properties.

[0004] However, existing PDMS coatings still face certain challenges in the application process, especially in terms of wear resistance, long-term stability and durability in harsh environments. The coatings often fall off easily or the hydrophobicity is weakened. In addition, the preparation method and process of PDMS coatings still have room for improvement to improve their performance and reduce production costs. Summary of the invention

[0005] In order to solve the above problems, the present invention aims to address the environmental pollution caused by fluorine-containing material coatings in the prior art, and the problems of easy detachment or weakened hydrophobicity of the coating in harsh environments. A preparation method that can significantly improve the hydrophobicity and wear resistance of fluorine-free PDMS coatings on glass surfaces is proposed. Through specific surface modification technology and appropriate process parameter regulation, the coating of the present invention can maintain excellent performance during long-term use, solving the deficiencies in the prior art and having good application prospects.

[0006] In order to achieve the above effects, the present invention provides a method for preparing a fluorine-free hydrophobic wear-resistant coating based on organosilane cross-linking, comprising the following steps: Step 1: Use an organic solvent to clean and decontaminate the glass substrate, and then use an ultraviolet ozone cleaning machine to activate its surface; Step 2: Dissolve the main agent PDMS and the cross-linking agent PMHS in a certain ratio in a solvent, mix them by ultrasound to prepare a uniform spraying liquid, and then age them at room temperature for use; Step 3: Apply the prepared spraying liquid to the glass substrate through a spray gun, and obtain a PDMS-PMHS hydrophobic coating with a three-dimensional cross-linked structure after curing. Furthermore, in the step 1, the substrate selected is a soda-lime glass of 100×100×1mm or 30×10×1mm, which is first ultrasonically cleaned with acetone for 10 to 30 minutes and then cleaned with ethanol for 10 to 30 minutes; the surface activation step is specifically to use an ultraviolet ozone cleaner to clean for 5 to 10 minutes, so that the glass surface has a large number of hydroxyl groups to achieve surface activation.

[0007] Furthermore, in step 2, the main agent PDMS is vinyl-terminated polydimethylsiloxane, and the cross-linking agent PMHS is poly(dimethylsiloxane-co-methylhydrogensiloxane).

[0008] Furthermore, in step 2, the solvent is one of ethanol, isopropanol, ethyl acetate, butyl acetate, and tetrahydrofuran.

[0009] Furthermore, in step 2, the mass ratio of main agent:crosslinking agent is (2-10):1, The preferred mass ratio of main agent: cross-linking agent is (2~5):1. Within this ratio range, the wear resistance of the coating is significantly improved. Specifically, after more than 1,100 friction tests, the water contact angle of the coating remains above 100°, and there are no obvious signs of wear on the surface. This ratio range can effectively balance the reaction rate of the main agent and the cross-linking agent, ensuring that the coating forms a denser and more stable three-dimensional cross-linked structure during the curing process, thereby significantly improving the mechanical strength and wear resistance of the coating. In addition, the coating within this ratio range not only has excellent hydrophobic properties, but also exhibits good adhesion, chemical stability and corrosion resistance, and is suitable for applications on a variety of substrates and in complex environments. Furthermore, the mass fraction of the main agent and the cross-linking agent in the spraying liquid is 0.1%~2%.

[0010] Furthermore, in the step 2, the specific configuration process of the spray liquid is as follows: select a suitable beaker, add a certain amount of solvent, and in order to avoid adding the main agent and the cross-linking agent at the same time, which makes the concentration of the two too high and directly reacts to produce solid colloidal substances, first dissolve the main agent in the solvent, mix it evenly by ultrasonication for 3-5 minutes, then add a certain proportion of the cross-linking agent, and then ultrasonically mix it for 0.5~1h. After mixing evenly, seal the mouth of the beaker with a sealing film and put it in a cool place. Age it at room temperature for 12~24h before use.

[0011] Furthermore, in the step three, the specific preparation process of the hydrophobic coating is as follows: the cleaned glass substrate is placed in a fume hood and fixed, and a spray gun is used to spray for 5-20 seconds at a distance of 10-20 cm from the glass substrate. The inner diameter of the nozzle of the spray gun is 0.3-0.5 mm, and the spraying pressure is set to 0.16-0.36 MPa.

[0012] Furthermore, in step three, the coating curing temperature is 100-180° C., and the curing time is 6-12 hours.

[0013] Beneficial effects of the present invention: 1) The present invention makes full use of fluorine-free PDMS as a coating material, provides excellent hydrophobicity, good temperature resistance and chemical resistance, and solves the disadvantage that fluorine-containing coating materials are not environmentally friendly.

[0014] 2) The present invention is based on the hydrosilylation reaction, using poly(dimethylsiloxane-co-methylhydrogensiloxane) as a crosslinking agent, and crosslinking with Dow Corning PDMS whose main component is vinyl-terminated polydimethylsiloxane (Vi-PDMS) to produce a three-dimensional network space structure, which fully exerts the characteristics of the three-dimensional network space structure, greatly improves the hardness and rigidity of the material, and thereby makes its surface more able to withstand friction and external forces, reduces surface wear, and solves the problem of the fluorine-containing coating being short-lasting and having poor mechanical properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings and other implementation methods can be obtained based on these drawings without creative work. In the drawings: Figure 1 This is the basic process for preparing the hydrophobic and wear-resistant coating in the embodiments of the present invention.

[0016] Figure 2 Optical pictures of water contact angles of the coatings of Examples 1-5 of the present invention.

[0017] Figure 3 This is a SEM surface morphology image of the hydrophobic and wear-resistant coating prepared in an embodiment of the present invention.

[0018] Figure 4 Graph 1 is the relationship between the number of wear times and the contact angle of the coatings with different crosslinking agent ratios in the embodiments of the present invention. DETAILED DESCRIPTION

[0019] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0020] It should be understood that when used in this specification and the appended claims, the term "comprising" indicates the presence of described features, integers, steps, operations, elements and / or components, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or collections.

[0021] In order to simplify the drawings, only the parts related to the present invention are schematically shown in each figure, and they do not represent the actual structure of the product. In addition, in order to simplify the drawings and facilitate understanding, in some figures, only one of the parts with the same structure or function is schematically drawn or marked. In this article, "one" not only means "only one", but also means "more than one".

[0022] It should be further understood that the term “and / or” used in the specification and appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0023] In the embodiments shown in the drawings, the indications of directions (such as up, down, left, right, front and back) used to explain the structure and movement of the various components of the present invention are not absolute but relative. These descriptions are appropriate when these components are in the positions shown in the drawings. If the descriptions of the positions of these components change, the indications of these directions also change accordingly.

[0024] In addition, in the description of the present application, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance.

[0025] The present invention provides a method for preparing a fluorine-free hydrophobic and wear-resistant coating having excellent hydrophobicity and mechanical properties, such as Figure 1 , which is the basic process for preparing hydrophobic coatings, is developed by spraying, based on chemical bond reactions, to form a three-dimensional network structure at a certain temperature, forming a dense coating. The mechanism diagram is shown below: Figure 1 shown.

[0026] Example 1 Step 1: Use organic solvent and ultraviolet ozone cleaning machine to efficiently decontaminate and activate the surface of the glass substrate; in step 1 (1) The substrates used are 100x100x1mm and 30x10x1mm soda-lime glass (2) Use an ultrasonic machine with an ultrasonic power of 200 W and an ultrasonic frequency of 40 kHz to perform ultrasonic cleaning with acetone and ethanol for 10 minutes respectively.

[0027] (3) UV ozone cleaning, time is 5 minutes (1 minute is ozone production time, 4 minutes is cleaning time) Step 2, dissolving the main agent PDMS and the cross-linking agent PMHS in ethyl acetate in a certain ratio, mixing by ultrasound to prepare a uniform spraying liquid, and then aging at room temperature for standby use; in step 2 (1) The preparation of the spraying liquid follows the following formula:

[0028] (2) Ethyl acetate was used as the solvent, Dow Corning polydimethylsiloxane was used as the main agent, poly(dimethylsiloxane-co-methylhydrogensiloxane) was used as the cross-linking agent, and the PDMS:PMHS ratio was 5:1, with a total concentration of 1%.

[0029] (3) The specific preparation process of the spray liquid is as follows: select a 100 ml beaker and add 50 g of ethyl acetate. To avoid adding the main agent and the cross-linking agent at the same time, which would result in too high a concentration of the two and a direct reaction to produce a solid colloidal substance, we first dissolved 0.5 g of the main agent PDMS in the solvent and mixed it evenly by ultrasonic for 3-5 minutes. Then, 0.1 g of the cross-linking agent PMHS was added and ultrasonically mixed for 0.5 hours. After mixing evenly, to prevent pollutants from entering, the beaker was sealed with a sealing film and placed in a cool place. It was aged at room temperature for 24 hours before use.

[0030] Step 3, applying the prepared spraying liquid to a glass substrate with a spray gun, and curing to obtain a PDMS-PMHS hydrophobic coating; in step 3, (1) The specific preparation process of the hydrophobic coating is as follows: the cleaned glass substrate is placed in a fume hood and fixed, and a spray gun is used to spray for 10 seconds at a distance of 15 cm from the glass substrate. The parameters of the spray gun are set as follows: the inner diameter of the nozzle is 0.3 mm, and the spraying pressure is set to 0.36 MPa.

[0031] (2) Place the coating in an oven at 150°C for high-temperature curing for 12 hours. During the curing process, a cross-linking reaction occurs to generate a three-dimensional cross-linked structure with a stable structure. After the curing is completed, a fluorine-free, hydrophobic, and wear-resistant coating is obtained.

[0032] Example 2 This embodiment is consistent with steps 1 and 3 of embodiment 1, except that in step 2 (2), the ratio of the main agent to the cross-linking agent is PDMS:PMHS=10:1. The other steps are the same as embodiment 1.

[0033] Example 3 This embodiment is consistent with steps 1 and 3 of embodiment 1, except that in step 2 (2), the ratio of the main agent to the cross-linking agent is PDMS:PMHS=2:1. The other steps are the same as embodiment 1.

[0034] Example 4 This embodiment is consistent with steps 1 and 3 of embodiment 1, except that in step 2 (2), the ratio of the main agent to the cross-linking agent is PDMS:PMHS=1:1. The other steps are the same as embodiment 1.

[0035] Example 5 This embodiment is consistent with steps 1 and 3 of embodiment 1, except that in step 2 (2), the ratio of the main agent to the cross-linking agent is PDMS:PMHS=1:2. The other steps are the same as embodiment 1.

[0036] In Examples 1-5, polydimethylsiloxane (PDMS) prepolymer (Sylgard 184A) was produced by Dow Corning; poly(dimethylsiloxane-co-methylhydrogensiloxane) (PMHS) (reagent grade, viscosity: 5-10 centipoise) was produced by Tianjin Xiensi Biochemical Technology Co., Ltd.; ethanol (EtOH, 99.7%) and ethyl acetate (EA, 99.5%) were provided by Wuhan Geao Chemical Technology Co., Ltd.; deionized water (homemade) and acetone (≥99.5%) were provided by Sinopharm Chemical Co., Ltd., and soda-lime glass (30*10*1mm) was provided by Luoyang Guluo Glass Co., Ltd.

[0037] The PDMS hydrophobic and wear-resistant coating prepared above was tested and analyzed, and the results are as follows: 1) The surface morphology SEM image of the PDMS hydrophobic wear-resistant coating prepared above shows that the wetting characteristics or water contact angle of the glass substrate surface are significantly affected by surface chemistry and surface morphology. The results of scanning electron microscopy (SEM) showed that at a 1% PDMS concentration, the morphological structure and surface energy of PDMS play a crucial role in determining the hydrophobicity of the material. Figure 3 (a) The acquired image depicts the PDMS microspheres filled with particles observed at 50 μm resolution. Figure 3 (b)(c), SEM images captured at 25 and 5 μm provide clear visualization of different PDMS particles at the microscopic scale.

[0038] 2) The wear resistance of the coatings of different embodiments was tested by a paint film abrasion tester (BGD 523, China). A CS-10F grinding wheel was used with a load of 500g. After each 100 wears, the surface was rinsed with ethanol, then rinsed with purified water, dried with nitrogen, and the contact angle was measured and the data was recorded. The standard for this patent is TSR7102G: Using a CS-10F grinding wheel, under a load of 4.9N, if the water contact angle after 1000r wear is still greater than 90°, it is defined as excellent wear resistance.

[0039] Table 1: Test results of various properties of samples of Examples 1-5

[0040] It can be seen from Examples 1-5 that when the mass ratio of the main agent: cross-linking agent is (2~5):1, within this ratio range, the wear resistance of the coating is significantly improved, specifically: after more than 1100 friction tests, the water contact angle of the coating remains above 100°, and there are no obvious signs of wear on the surface. This ratio range can effectively balance the reaction rate of the main agent and the cross-linking agent, ensuring that the coating forms a denser and more stable three-dimensional cross-linked structure during the curing process, thereby significantly improving the mechanical strength and wear resistance of the coating. In addition, the coating within this ratio range not only has excellent hydrophobic properties, but also exhibits good adhesion, chemical stability and corrosion resistance, and is suitable for applications on a variety of substrates and in complex environments.

[0041] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A method for preparing a fluorine-free hydrophobic wear-resistant coating based on organosilane cross-linking, characterized in that: The steps include: Step 1: Use an organic solvent to clean and decontaminate the glass substrate, and then use an ultraviolet ozone cleaning machine to activate its surface; Step 2: Dissolve the main agent PDMS and the cross-linking agent PMHS in a certain ratio in a solvent, mix them by ultrasound to prepare a uniform spraying liquid, and then age them at room temperature for use; Step 3: Apply the prepared spraying liquid to the glass substrate through a spray gun, and obtain a PDMS-PMHS hydrophobic coating with a three-dimensional cross-linked structure after curing.

2. The preparation method according to claim 1, characterized in that: In the step one, the decontamination step is specifically to first use acetone ultrasonic cleaning for 10 to 30 minutes, and then use ethanol cleaning for 10 to 30 minutes; the surface activation step is specifically to use an ultraviolet ozone cleaning machine to clean for 5 to 10 minutes, so that the glass surface has a large number of hydroxyl groups to achieve surface activation.

3. The preparation method according to claim 1, characterized in that: In step 2, the main agent PDMS is vinyl-terminated polydimethylsiloxane, and the cross-linking agent PMHS is poly(dimethylsiloxane-co-methylhydrogensiloxane).

4. The preparation method according to claim 1, characterized in that: In step 2, the solvent is one of ethanol, isopropanol, ethyl acetate, butyl acetate and tetrahydrofuran.

5. The preparation method according to claim 1 or 3, characterized in that: In step 2, the mass ratio of the main agent: the cross-linking agent is (2-10): 1; preferably, the mass ratio of the main agent: the cross-linking agent is (2-5): 1; the mass fraction of the main agent and the cross-linking agent in the spraying liquid is 0.1%-2%.

6. The preparation method according to claim 1, characterized in that: In the step 2, the specific configuration process of the spray liquid is as follows: select a suitable beaker, add a certain amount of solvent, first dissolve the main agent in the solvent, mix evenly by ultrasonic for 3-5 minutes, then add a certain proportion of cross-linking agent, and then ultrasonically mix for 0.5-1h. After mixing evenly, seal the beaker mouth with a sealing film and put it in a cool place, and age it at room temperature for 12-24h before use.

7. The preparation method according to claim 1, characterized in that: In the step three, the specific preparation process of the hydrophobic coating is as follows: the cleaned glass substrate is placed in a fume hood and fixed, and a spray gun is used to spray for 5-20 seconds at a distance of 10-20 cm from the glass substrate. The inner diameter of the nozzle of the spray gun is 0.3-0.5 mm, and the spraying pressure is set to 0.16-0.36 MPa.

8. The preparation method according to claim 1, characterized in that: In the step 3, the coating is cured at a temperature of 100-180° C. and a curing time of 6-12 hours.

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