Preparation method of dustproof hydrophobic coating of automobile rearview mirror

Abstract

The invention provides a preparation method of a dustproof hydrophobic coating for an automobile rearview mirror, which comprises the following steps: sequentially adding a hydrophobic silane coupling agent, a condensable silane coupling agent, tetramethyl orthosilicate, H, 1H, 2H, 2H-perfluorodecyl trichlorosilane, 15-25 parts of silicon tetrachloride and a lubricant into a dehydrated solvent to obtain the dustproof hydrophobic coating. According to the preparation method, tetramethyl silicate with relatively low reaction activity is used as a raw material to react with silicon tetrachloride to form an intermediate species with moderate activity, and then a linear chain polymer modification layer capable of freely performing chain extension and recombination is pre-formed on the surface by utilizing the difference of reaction rates; the problems of coating damage and adhesive force reduction caused by severe shrinkage are avoided; the fluorosilane substance can also form an organic silicon linear polymer with a fluorosilane side chain with tetramethyl silicate and silicon tetrachloride, and the organic silicon linear polymer and a linear chain polymer modification layer form a microphase separation behavior in molecular chain movement, so that a perfluoro side chain with lower surface energy is promoted to migrate to the surface of the coating, and better comprehensive performance is obtained.

Description

Technical Field

[0001] The present invention relates to the technical field of coatings, and in particular to a method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile. Background Art

[0002] With the rapid development of the automotive industry, improving driving safety has become a key focus of technological research and development. As a core component that allows drivers to observe the environment behind the vehicle, the surface cleanliness and clarity of the rearview mirror directly impact driving safety. In rainy, foggy, or high-humidity environments, water droplets or mist easily adhere to the rearview mirror surface, causing light scattering and blurred images. Furthermore, moisture accelerates the accumulation of dust on the rearview mirror surface, severely interfering with the driver's vision and increasing the risk of traffic accidents.

[0003] Traditional solutions address water stains on rearview mirror surfaces through physical structures (such as heating devices) or chemical coatings (such as hydrophobic materials). Hydrophobic coatings have attracted widespread attention due to their low cost and lack of energy consumption. However, existing hydrophobic coating technology still has the following limitations:

[0004] 1. Insufficient durability: Most hydrophobic coatings (such as fluorocarbons or silicone-based materials) are prone to degradation after long-term exposure to ultraviolet rays, extreme temperatures or mechanical friction (such as wiper scratches), resulting in a significant decrease in hydrophobic performance and requiring frequent maintenance or replacement.

[0005] 2. Poor environmental adaptability: The hydrophobic effect of existing coatings is weakened or even fails in highly polluted environments (such as oil and dust adhesion) or low-temperature icing conditions, which limits their practical application scenarios.

[0006] 3. Complex preparation process: Some high-performance coatings (such as nanostructured hydrophobic layers) rely on vacuum deposition or photolithography technology, which has high production costs and complex processes, making it difficult to achieve large-scale mass production.

[0007] Therefore, there is a need for a hydrophobic coating that is dust-proof, durable, and adaptable to highly polluted environments. Summary of the Invention

[0008] The present invention aims to solve the problems of dispersibility, durability and density of hydrophobic coatings and provides a method for preparing a dust-proof hydrophobic coating for automobile rearview mirrors. The method uses tetramethyl silicate with low reactivity as a raw material to react with silicon tetrachloride to form an intermediate species with moderate activity. The difference in reaction rate is then used to pre-form a linear chain polymer modification layer on the surface that can freely undergo chain extension and recombination. This avoids the problems of coating damage and decreased adhesion caused by drastic shrinkage, thereby improving dispersibility.

[0009] The present invention provides a method for preparing a dustproof hydrophobic coating for an automobile rearview mirror, comprising the following steps:

[0010] S1. Pretreatment: adding a dehydrating agent to 30 to 80 parts by weight of an organic solvent, stirring and then allowing to stand, filtering out the residual dehydrating agent to obtain a dehydrated solvent, wherein the organic solvent is n-hexane, cyclohexane or cyclopentane;

[0011] S2, adding 1 to 20 parts by mass of a hydrophobic silane coupling agent to the dehydrated solvent;

[0012] S3, adding 5 to 20 parts by mass of a condensable silane coupling agent;

[0013] S4, sequentially adding 1 to 5 parts by mass of methyl orthosilicate, 3 to 10 parts by mass of H,1H,2H,2H-perfluorodecyltrichlorosilane, and 15 to 25 parts by mass of silicon tetrachloride;

[0014] Methyl orthosilicate reacts with silicon tetrachloride to form an intermediate species, and then the reaction rate difference of the intermediate species is used to pre-form a linear chain polymer modification layer on the surface. The linear chain polymer modification layer is a polysiloxane that is liquid at room temperature and can freely undergo chain extension and recombination.

[0015] H,1H,2H,2H-perfluorodecyltrichlorosilane forms an organosilicon linear polymer with fluorosilane side chains with methyl orthosilicate and silicon tetrachloride;

[0016] The condensable silane coupling agent can undergo condensation reaction with methyl orthosilicate and silicon tetrachloride;

[0017] S5, adding 2 to 8 parts by weight of a lubricant to obtain a dust-proof hydrophobic coating;

[0018] S6. The automobile rearview mirror is repeatedly immersed in a dustproof hydrophobic coating and taken out 1 to 20 times to obtain a dustproof hydrophobic coating, or the dustproof hydrophobic coating is obtained on the surface of the automobile rearview mirror by spraying or evaporating. A method for preparing a dustproof hydrophobic coating for an automobile rearview mirror is completed.

[0019] The method for preparing a dust-proof hydrophobic coating for a rearview mirror of an automobile described in the present invention is preferably such that in step S1, the dewatering agent is 10 parts by mass of anhydrous calcium chloride, and the mixture is stirred and allowed to stand for 2 hours before filtering out residual calcium chloride.

[0020] In the method for preparing a dust-proof hydrophobic coating for a rearview mirror of an automobile described in the present invention, as a preferred embodiment, in step S1, the dehydrating agent is magnesium sulfate, molecular sieve, or silica gel.

[0021] The present invention provides a method for preparing a dust-proof hydrophobic coating for a rearview mirror of an automobile. As a preferred embodiment, in step S2, the hydrophobic silane coupling agent is nonafluorohexyltrichlorosilane, and the hydrophobic silane coupling agent is used to reduce the surface energy of the coating; in step S3, the condensable silane coupling agent is octadecyltrichlorosilane; and in step S5, the lubricant is dimethyldichlorosilane, and the lubricant is used to promote the sliding of water droplets from the surface of the dust-proof hydrophobic coating.

[0022] The method for preparing a dust-proof hydrophobic coating for a rearview mirror of an automobile according to the present invention is preferably such that, in step S6, a condensable silane coupling agent is subjected to a condensation reaction with methyl orthosilicate and silicon tetrachloride to form a surface dense structure on the rearview mirror of the automobile. The surface dense structure is:

[0023]

[0024] The method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile according to the present invention is preferably such that in step S4, the intermediate species rapidly reacts with water, polymerizes, and then slowly reacts with water. The intermediate species is:

[0025]

[0026] The linear chain polymer modified layer is a continuous Si—O—Si skeleton structure formed by condensation reaction. The structural formula of the linear chain polymer modified layer is:

[0027]

[0028] In the method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile according to the present invention, as a preferred embodiment, the slow reaction in step S4 is extended to step S6;

[0029] In step S6, the hydroxyl groups on the surface of the automobile rearview mirror glass participate in a slow reaction.

[0030] The method for preparing a dust-proof hydrophobic coating for a rearview mirror of an automobile described in the present invention is, as a preferred embodiment, that in step S4, the linear chain polymer modification layer and the organic silicon linear polymer with fluorosilane side chains form microphase separation behavior during molecular chain movement due to the surface energy difference, so that the organic silicon linear polymer with fluorosilane side chains with low surface energy migrates to the surface of the dust-proof hydrophobic coating.

[0031] In the method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile according to the present invention, as a preferred embodiment, the organosilicon linear polymer with fluorosilane side chains is:

[0032]

[0033] In the method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile described in the present invention, as a preferred embodiment, the ambient humidity in steps S2 to S5 is 10 to 30%.

[0034] Although there are studies on the direct formation of silicon dioxide nanostructures using silicon tetrachloride, the molecular weight of silicon tetrachloride decreases sharply (169.9 to 60.08) during the reaction of silicon tetrachloride to silicon dioxide, while the density increases (1.48 g / cm 3 , silicon dioxide 2.65g / cm 3 ), causing the formed silica coating to shrink violently and break into nanoparticles, making it impossible to obtain a continuous and firmly attached coating.

[0035] The present invention uses tetramethyl silicate, a relatively low-reactivity raw material, as a reaction with silicon tetrachloride to form a moderately active intermediate species. This difference in reaction rate is then exploited to pre-form a linear chain polymer modification layer on the surface. This type of polysiloxane is liquid at room temperature and can freely undergo chain extension and recombination, thus avoiding coating damage and decreased adhesion caused by drastic shrinkage.

[0036]

[0037] Fluorosilanes added to the coating can also participate in this type of reaction, forming linear silicone polymers with fluorosilane side chains. During the polysiloxane recombination process, the surface energy difference between the perfluorinated side chains and the polysiloxane (8-15 mN / m) is large, resulting in microphase separation during molecular chain movement, prompting the perfluorinated side chains with lower surface energy to migrate to the coating surface. This enables this technology to achieve better overall performance under the same perfluorinated compound addition conditions.

[0038]

[0039] At the same time, octadecyltrichlorosilane can also participate in this type of reaction, forming a dense surface structure on substrates such as glass, reducing the surface energy of the material and further improving the hydrophobic properties of the material.

[0040]

[0041] During the reaction, hydroxyl groups (—OH) on the glass surface may participate in the condensation reaction, allowing the polymer to firmly bond to the glass substrate through Si—O—Si bonds, forming a stable interfacial layer. This chemical bonding method has stronger resistance to peeling than physical adsorption. The linear chain polymer forms a continuous Si—O—Si skeleton structure through the condensation reaction. This continuous covalent bond network reduces terminal defects in the structure and reduces the possibility of molecular chain breakage. The local network structure characteristics similar to silica also enhance the overall stability. The Si—O bonds formed in the polymer have a higher bond energy (approximately 452 kJ / mol) and are more difficult to break than other chemical bonds. Organic groups such as methyl (—CH3) introduced by tetramethyl silicate can shield the Si—O main chain through steric hindrance, reducing the probability of attack on the polymer chain by water molecules or other corrosive substances in the environment.

[0042] 1H,1H,2H,2H-perfluorodecyltrichlorosilane and nonafluorohexyltrichlorosilane are both hydrophobic silane coupling agent molecules that can reduce the surface energy of the coating, that is, reduce the adhesion of dust to the coating; at the same time, they increase the rigidity of the coating. Too high a content will easily cause the coating to turn white.

[0043] Dimethyldichlorosilane can increase the lubricity of the coating surface, that is, promote the sliding of water droplets from the coating surface; at the same time, it increases the flexibility of the coating, reduces cracking and reduces whitening.

[0044] Regulating the ratio of these molecules can improve the overall dustproof, waterproof and light transmittance performance of the coating.

[0045] Fast\slow refers to the speed of a chemical reaction.

[0046] The present invention has the following advantages:

[0047] (1) The present invention uses tetramethyl silicate with low reactivity as a raw material to react with silicon tetrachloride to form an intermediate species with moderate activity, and then uses the difference in reaction rate to pre-form a linear chain polymer modification layer on the surface that can freely extend and reorganize the chain, thereby avoiding the problems of coating damage and decreased adhesion caused by severe shrinkage, thereby improving dispersibility.

[0048] (2) The fluorosilane substances in the present invention can also form organic silicon linear polymers with fluorosilane side chains with tetramethyl silicate and silicon tetrachloride, forming microphase separation behavior with the linear chain polymer modified layer during molecular chain movement, prompting the perfluorinated side chains with lower surface energy to migrate to the coating surface, thereby obtaining better comprehensive performance.

[0049] (3) Octadecyltrichlorosilane in the present invention can also participate in this type of reaction to form a dense surface structure on the glass substrate, thereby reducing the surface energy of the material and further improving the hydrophobicity of the material.

[0050] (4) The coating of the present invention can condense with the hydroxyl groups on the glass surface, so that the polymer is firmly bonded to the glass substrate through Si—O—Si bonds, forming a stable interface layer. In addition, the organic groups such as methyl introduced by tetramethyl silicate can shield the Si—O main chain through the steric effect, thereby reducing the probability of water molecules or other corrosive substances in the environment attacking the polymer chain.

[0051] (5) This coating is easy to prepare and can effectively prevent dust, keep the surface of the car rearview mirror clean, and reduce interference with the driver's vision. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 The present invention is a flow chart of a method for preparing a dust-proof hydrophobic coating for a rearview mirror of an automobile;

[0053] Figure 2 This is a comparison chart of the reflectivity of a rearview mirror before and after coating treatment, in Example 1 of a method for preparing a dustproof hydrophobic coating for a rearview mirror;

[0054] Figure 3 This is a comparison diagram of the dustproof effect of the automobile rearview mirror before (left) and after (right) coating treatment, according to Example 1 of a method for preparing a dustproof hydrophobic coating for an automobile rearview mirror;

[0055] Figure 4 This is a comparison chart of the reflectivity of a rearview mirror before and after coating treatment, which is a method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile in Example 2;

[0056] Figure 5 This is a comparison diagram of the dustproof effect of the automobile rearview mirror before (left) and after (right) coating treatment of Example 2 of a method for preparing a dustproof hydrophobic coating for an automobile rearview mirror;

[0057] Figure 6 This is a diagram of a car rearview mirror before coating treatment, in Example 3 of a method for preparing a dustproof hydrophobic coating for a car rearview mirror;

[0058] Figure 7 This is a comparison diagram of the dustproof effect of the automobile rearview mirror before (left) and after (right) coating treatment of Example 3 of a method for preparing a dustproof hydrophobic coating for an automobile rearview mirror. DETAILED DESCRIPTION

[0059] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments.

[0060] Example 1

[0061] like Figure 1As shown, a method for preparing a dust-proof hydrophobic coating for a rearview mirror of an automobile is provided, wherein the hydrophobic coating is composed of the following raw materials: nonafluorohexyltrichlorosilane, octadecyltrichlorosilane, methyl orthosilicate, silicon tetrachloride, n-hexane, and dimethyldichlorosilane, wherein the raw materials include 10 parts of nonafluorohexyltrichlorosilane, 5 parts of octadecyltrichlorosilane, 1 part of methyl orthosilicate, 3 parts of 1H,1H,2H,2H-perfluorodecyltrichlorosilane, 40 parts of n-hexane, 15 parts of silicon tetrachloride, 3 parts of dimethyldichlorosilane, and 10 parts of anhydrous calcium chloride;

[0062] like Figure 1 As shown, the specific preparation steps are:

[0063] S1. Pretreatment: Add 10 parts of anhydrous calcium chloride to 40 parts of n-hexane by mass, stir, and let stand for 2 hours to remove water from the solvent;

[0064] Filtering the solvent containing anhydrous calcium chloride to remove calcium chloride residue;

[0065] S2. Add 10 parts by mass of nonafluorohexyltrichlorosilane to the solvent after water removal;

[0066] S3. Add 5 parts of octadecyltrichlorosilane to the above system according to the mass fraction;

[0067] S4. Add 1 part of methyl orthosilicate, 3 parts of H,1H,2H,2H-perfluorodecyltrichlorosilane, and 15 parts of silicon tetrachloride to the above system according to their mass ratios;

[0068] S5. Add 3 parts of dimethyldichlorosilane to the above system according to the mass fraction and stir evenly to obtain a hydrophobic coating with a dust-proof effect;

[0069] S6. Repeatedly immerse the rearview mirror in the hydrophobic coating and take it out five times, or obtain a hydrophobic coating on the surface by spraying, evaporation, etc.

[0070] Example 2

[0071] A method for preparing a dust-proof hydrophobic coating for a rearview mirror of an automobile. The hydrophobic coating is composed of the following raw materials: nonafluorohexyltrichlorosilane, octadecyltrichlorosilane, methyl orthosilicate, silicon tetrachloride, cyclohexane, and dimethyldichlorosilane. The raw materials include 11 parts of nonafluorohexyltrichlorosilane, 7 parts of octadecyltrichlorosilane, 2.5 parts of methyl orthosilicate, 5 parts of 1H,1H,2H,2H-perfluorodecyltrichlorosilane, 70 parts of cyclohexane, 16 parts of silicon tetrachloride, 4.2 parts of dimethyldichlorosilane, and 10 parts of anhydrous calcium chloride.

[0072] The preparation method of the dustproof hydrophobic coating of this embodiment is the same as that of Example 1.

[0073] Example 3

[0074] A method for preparing a dust-proof hydrophobic coating for a rearview mirror of an automobile. The hydrophobic coating is composed of the following raw materials: nonafluorohexyltrichlorosilane, octadecyltrichlorosilane, methyl orthosilicate, silicon tetrachloride, cyclopentane, and dimethyldichlorosilane. The raw materials include 15 parts of nonafluorohexyltrichlorosilane, 6.3 parts of octadecyltrichlorosilane, 5.1 parts of methyl orthosilicate, 7.2 parts of 1H,1H,2H,2H-perfluorodecyltrichlorosilane, 55 parts of cyclopentane, 20 parts of silicon tetrachloride, 7 parts of dimethyldichlorosilane, and 10 parts of anhydrous calcium chloride.

[0075] The preparation method of the dustproof hydrophobic coating of this embodiment is the same as that of Example 1.

[0076] like Figure 2 、 4 As shown in Figure 6, after the dust-proof and hydrophobic coating is applied, the reflectivity of light on the surface of the rearview mirror glass is almost zero in the visible light range, so that more light can pass through the glass and reach the reflective layer at the bottom of the mirror, thus making the field of vision clearer.

[0077] like Figure 3 、 5 As shown in Figures 7 and 8, the dustproof effect of Examples 1 to 3 is relatively obvious. In addition, after being irradiated with a xenon lamp for 1000 hours, Examples 1 to 3 still have the dustproof and hydrophobic effect, showing extremely high stability.

[0078] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile, characterized in that: The following steps are involved: S1, pretreatment: adding a dehydrating agent to 30 to 80 parts by weight of an organic solvent, stirring and then allowing to stand, filtering out the residual dehydrating agent to obtain a dehydrated solvent, wherein the organic solvent is n-hexane, cyclohexane or cyclopentane; S2, adding 1 to 20 parts by mass of a hydrophobic silane coupling agent to the dehydrated solvent; S3, adding 5 to 20 parts by mass of a condensable silane coupling agent; S4, sequentially adding 1 to 5 parts by mass of methyl orthosilicate, 3 to 10 parts by mass of H,1H,2H,2H-perfluorodecyltrichlorosilane, and 15 to 25 parts by mass of silicon tetrachloride; Methyl orthosilicate reacts with silicon tetrachloride to form an intermediate species, and then utilizes the reaction rate difference of the intermediate species to pre-form a linear chain polymer modification layer on the surface. The linear chain polymer modification layer is a polysiloxane that is liquid at room temperature and can freely undergo chain extension and recombination; H,1H,2H,2H-perfluorodecyltrichlorosilane forms an organosilicon linear polymer with fluorosilane side chains with methyl orthosilicate and silicon tetrachloride; The condensable silane coupling agent undergoes a condensation reaction with methyl orthosilicate and silicon tetrachloride; S5, adding 2 to 8 parts by weight of a lubricant to obtain a dust-proof hydrophobic coating; S6. The dust-proof hydrophobic coating is repeatedly immersed in and taken out of the automobile rearview mirror for 1 to 20 times to obtain a dust-proof hydrophobic coating, or the dust-proof hydrophobic coating is obtained by spraying or evaporating on the surface of the automobile rearview mirror. A method for preparing a dust-proof hydrophobic coating for an automobile rearview mirror is completed.

2. The method for preparing a dustproof hydrophobic coating for a rearview mirror according to claim 1, wherein: In step S1, the dehydrating agent is 10 parts by mass of anhydrous calcium chloride, and after stirring, the mixture is allowed to stand for 2 hours and the residual calcium chloride is filtered out.

3. The method for preparing a dustproof hydrophobic coating for a rearview mirror according to claim 1, wherein: In step S1, the dehydrating agent is magnesium sulfate, molecular sieve or silica gel.

4. The method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile according to claim 1, wherein: In step S2, the hydrophobic silane coupling agent is nonafluorohexyltrichlorosilane, and the hydrophobic silane coupling agent is used to reduce the surface energy of the coating; in step S3, the condensable silane coupling agent is octadecyltrichlorosilane, and in step S5, the lubricant is dimethyldichlorosilane, and the lubricant is used to promote water droplets to slide off the surface of the dust-proof and hydrophobic coating.

5. The method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile according to claim 4, characterized in that: In step S6, the condensable silane coupling agent undergoes a condensation reaction with methyl orthosilicate and silicon tetrachloride to form a surface dense structure on the automobile rearview mirror. The surface dense structure is:

6. The method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile according to claim 1, characterized in that: In step S4, the intermediate species reacts rapidly with water, polymerizes, and then reacts slowly with water. The intermediate species is: The linear chain polymer modified layer is a continuous Si—O—Si skeleton structure formed by condensation reaction. The structural formula of the linear chain polymer modified layer is:

7. The method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile according to claim 6, characterized in that: The slow reaction in step S4 is extended to step S6; In step S6, the hydroxyl groups on the surface of the automobile rearview mirror glass participate in a slow reaction.

8. The method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile according to claim 1, characterized in that: In step S4, the linear chain polymer modified layer and the organic silicon linear polymer with fluorosilane side chains form microphase separation behavior during molecular chain movement due to the surface energy difference, so that the organic silicon linear polymer with fluorosilane side chains with low surface energy migrates to the surface of the dust-proof and hydrophobic coating.

9. The method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile according to claim 8, characterized in that: The organosilicon linear polymer with fluorosilane side chains is:

10. The method for preparing a dustproof hydrophobic coating for a rearview mirror of an automobile according to claim 1, characterized in that: The ambient humidity in steps S2 to S5 is 10% to 30%.

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