A method for preparing a high-hardness, transparent, fluorine-free liquid-repellent coating

Abstract

The application discloses a preparation method of high-hardness, transparent and fluorine-free liquid-repellent coating and belongs to the technical field of high polymer functional materials and polymer coating. Hydroxyl silicone oil, epoxy resin, isocyanate derivative, melamine formaldehyde resin and polyether modified silicone oil are fully dissolved in an organic solvent, coated on a substrate and heated and solidified in one step to obtain the high-hardness, transparent and fluorine-free liquid-repellent coating. The coating prepared by the application is transparent, liquid-repellent and has excellent hardness and can be constructed on the substrate by means of drop coating, dip coating and spin coating. The raw materials are cheap and easy to obtain, the preparation process is fluorine-free and controllable, and the application has wide application value.

Description

Technical Field

[0001] This invention belongs to the field of polymer functional materials and polymer coating technology, specifically relating to a method for preparing a high-hardness, transparent, fluorine-free liquid-repellent coating. Background Technology

[0002] High-hardness, transparent liquid-repellent surfaces have broad application prospects in antifouling, self-cleaning, anti-icing, and anti-corrosion. Based on differences in surface roughness, they can be divided into two main categories: superhydrophobic surfaces and smooth surfaces. Superhydrophobic surfaces typically require intricate surface structure design and the introduction of a large amount of long-chain fluorinated substances with extremely low surface energy to achieve their dual hydrophobicity, which is not only costly but also environmentally unfriendly. Furthermore, the micro / nano structures are easily damaged by external mechanical wear, reducing their durability. Smooth surfaces are mainly divided into two types: one is a porous surface injected with lubricant. This type of surface usually requires the construction of a porous, fine structure, and the lubricant is easily lost in practical applications, making it uneconomical and not durable. The other type is a smooth polymer surface, usually constructed from macromolecular polymers through a series of cross-linking reactions. The surface layer has a lubricating layer formed by polymer chains with high mobility and low surface energy, thereby weakening the interaction with external substances and playing an anti-adhesion role.

[0003] However, smooth polymer surfaces typically exhibit low mechanical strength, and constructing the polymer matrix often requires multiple synthetic steps to build suitable intermediates, resulting in cumbersome processes, high raw material costs, low product yields, and the unavoidable use of highly toxic solvents. Furthermore, overly complex organic polymers are difficult to control for compatibility with other polymers, making it challenging to co-construct transparent coatings and limiting their application in transparent protective materials. Therefore, constructing high-mechanical-strength, transparent, and environmentally friendly liquid-repellent coatings has become a major challenge. Summary of the Invention

[0004] The purpose of this invention is to provide a method for preparing a smooth polymer coating that is transparent, has high hardness, and achieves excellent liquid-repellent properties without the addition of fluorine-containing substances. At the same time, the preparation process is simple and easy to control, the raw material cost is low, and it has extremely high value for large-scale application.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A method for preparing a high-hardness, transparent, fluorine-free liquid-repellent coating, the specific steps of which are as follows:

[0007] (1) Preparation of mixed solutions

[0008] Hydroxy-hydroxy silicone oil, polyether-modified silicone oil, epoxy resin, isocyanate derivatives, and melamine-formaldehyde resin are fully dissolved in an organic solvent.

[0009] (2) Preparation of high-hardness, transparent fluorine-free liquid-repellent coating

[0010] The mixed solution is applied to a clean substrate and then heated to cure.

[0011] Furthermore, the organic solvent mentioned in step (1) is an ester compound or a ketone compound.

[0012] Further, the mass ratio of hydroxyl silicone oil, polyether modified silicone oil, epoxy resin, isocyanate derivative and melamine formaldehyde resin in step (1) is 0.009~0.18:0.009~0.45:0.5:0.1~2:0.1~1.

[0013] Furthermore, the coating method in step (2) is any one of drip coating, spin coating, or dip coating.

[0014] Furthermore, the heating temperature in step (2) is 130~210 ℃ and the time is 0.5~3 h.

[0015] Hydroxyl silicone oil not only possesses low surface energy, contributing to its antifouling and self-cleaning properties, but also contains hydroxyl functional groups, which can be used to reactively construct polymer cross-linked networks. Epoxy resins are inexpensive, and their epoxy and hydroxyl groups can react with isocyanate groups in isocyanate derivatives to construct spatial cross-linked networks with high mechanical strength. Melamine-formaldehyde resin has high transparency and hardness, and can be used as a curing agent for epoxy resins. These substances contribute to achieving coatings with liquid repellency, high hardness, and high transparency.

[0016] The beneficial effects of this invention are as follows:

[0017] (1) The raw materials are inexpensive and readily available, and the one-step preparation process is simple and easy to control.

[0018] (2) The coating has excellent liquid repellency and is capable of anti-fouling and self-cleaning.

[0019] (3) The coating has high transparency.

[0020] (4) The coating has excellent hardness.

[0021] (5) The coating can be applied to substrates such as glass and steel sheets by means of drop coating, spin coating, dip coating, etc. Attached Figure Description

[0022] Figure 1 This paper presents different comparative examples and embodiments of a high-hardness, transparent, fluorine-free liquid-repellent coating of the present invention, comparing water contact angle and pencil hardness.

[0023] Figure 2This is a comparison of the light transmittance of different comparative examples and embodiments of a high-hardness, transparent, fluorine-free liquid-repellent coating of the present invention.

[0024] Figure 3 This invention relates to an anti-graffiti test of a high-hardness, transparent, fluorine-free liquid-repellent coating. Detailed Implementation

[0025] To make the content of this invention easier to understand, the technical solution of this invention will be further described below with reference to specific embodiments, but this invention is not limited thereto.

[0026] The manufacturers and models of some of the raw materials used in the preparation are as follows:

[0027] The hydroxyl-terminated silicone oil is a hydroxyl-terminated polydimethylsiloxane: purchased from Shanghai Maclean Biochemical Co., Ltd., with a viscosity of 40 cst;

[0028] Polyether-modified silicone oil: purchased from Shanghai Maclean Biochemical Co., Ltd., viscosity 1000 cst;

[0029] Epoxy resin: purchased from Danbao Resin Co., Ltd., model E-44 (6101);

[0030] The isocyanate derivative is hexamethylene diisocyanate trimer: purchased from Shanghai Maclean Biochemical Co., Ltd.

[0031] The melamine-formaldehyde resin is a methyl etherified high-imino melamine-formaldehyde resin: purchased from Zhanxin Resin Co., Ltd., model number CYMEL 325.

[0032] Example 1

[0033] Step 1: Preparation of the mixed solution

[0034] Hydroxyhydrosilicone oil, polyether-modified silicone oil, epoxy resin, isocyanate derivative, and melamine-formaldehyde resin were fully dissolved in ethyl acetate at a mass ratio of 0.045:0.018:0.5:0.8:0.5.

[0035] Step 2: Preparation of a high-hardness, transparent, fluorine-free liquid-repellent coating

[0036] The mixed solution is spin-coated onto a clean glass substrate. After being placed in a 210 °C heating and drying oven for 2 hours, a high-hardness, transparent fluorine-free liquid-repellent coating (PEHMC coating) is obtained.

[0037] Example 2

[0038] Step 1: Preparation of the mixed solution

[0039] Hydroxyhydrosilicone oil, polyether-modified silicone oil, epoxy resin, isocyanate derivative, and melamine-formaldehyde resin were fully dissolved in ethyl acetate at a mass ratio of 0.045:0.018:0.5:0.8:0.5.

[0040] Step 2: Preparation of a high-hardness, transparent, fluorine-free liquid-repellent coating

[0041] The mixed solution is spin-coated onto a clean glass substrate. After being placed in a 210 °C heating and drying oven for 2.5 h, a high-hardness, transparent fluorine-free liquid-repellent coating (PEHMC coating) is obtained.

[0042] Comparative Example 1

[0043] Step 1: Preparation of the mixed solution

[0044] Hydroxyhydrosilicone oil, polyether-modified silicone oil, epoxy resin, isocyanate derivative, and melamine-formaldehyde resin were fully dissolved in ethyl acetate at a mass ratio of 0:0.018:0.5:0.8:0.

[0045] Step 2: Preparation of a high-hardness, transparent, fluorine-free liquid-repellent coating

[0046] Spin-coating the mixed solution onto a clean glass substrate. After placing it in a 150 °C drying oven for 2 hours, a control coating is obtained.

[0047] Comparative Example 2

[0048] Step 1: Preparation of the mixed solution

[0049] Hydroxyhydrosilicone oil, polyether-modified silicone oil, epoxy resin, isocyanate derivative, and melamine-formaldehyde resin were fully dissolved in ethyl acetate at a mass ratio of 0:0.018:0.5:0:0.5.

[0050] Step 2: Preparation of a high-hardness, transparent, fluorine-free liquid-repellent coating

[0051] Spin-coating the mixed solution onto a clean glass substrate. After placing it in a 150 °C drying oven for 2 hours, a control coating is obtained.

[0052] Comparative Example 3

[0053] Step 1: Preparation of the mixed solution

[0054] Hydroxyhydrosilicone oil, polyether-modified silicone oil, epoxy resin, isocyanate derivative, and melamine-formaldehyde resin were fully dissolved in ethyl acetate at a mass ratio of 0:0.018:0.5:0.8:0.5.

[0055] Step 2: Preparation of a high-hardness, transparent, fluorine-free liquid-repellent coating

[0056] Spin-coating the mixed solution onto a clean glass substrate. After placing it in a 150 °C drying oven for 2 hours, a control coating is obtained.

[0057] Comparative Example 4

[0058] Step 1: Preparation of the mixed solution

[0059] Hydroxyhydrosilicone oil, polyether-modified silicone oil, epoxy resin, isocyanate derivative, and melamine-formaldehyde resin were fully dissolved in ethyl acetate at a mass ratio of 0.045:0.018:0.5:0.8:0.5.

[0060] Step 2: Preparation of a high-hardness, transparent, fluorine-free liquid-repellent coating

[0061] Spin-coating the mixed solution onto a clean glass substrate. After placing it in a 150 °C drying oven for 2 hours, a control coating is obtained.

[0062] The performance testing methods for the coatings obtained in Examples 1-2 and Comparative Examples 1-4 are as follows:

[0063] Water contact angle: The contact angle of the coating with a 4 μL water droplet was determined using a contact angle measuring instrument and its supporting software.

[0064] Pencil hardness test: The pencil hardness of the coating is tested according to ASTM D3363.

[0065] Transmittance: Transmittance was measured using a UV-Vis spectrophotometer, and the ratio of the transmittance of the coated sample to that of the glass substrate at a wavelength of 550 nm was taken as the relative transmittance.

[0066] Anti-graffiti test: Write "FZU" on the glass substrate and the coating surface with an oil-based pen, then wipe with a tissue and observe the phenomenon.

[0067] The performance test results of the examples and comparative examples are shown in [link to example]. Figure 1 , Figure 2 .

[0068]

[0069] In the above embodiments, a high-hardness, transparent, fluorine-free liquid-repellent coating was successfully prepared through reasonable design.

[0070] Figure 1 This document presents different comparative examples and embodiments of a high-hardness, transparent, fluorine-free liquid-repellent coating of the present invention, comparing water contact angles and pencil hardness. For example... Figure 1 As shown, the coating in this embodiment has a high water contact angle and high hardness.

[0071] Figure 2This is a comparison of the light transmittance of different comparative examples and embodiments of a high-hardness, transparent, fluorine-free liquid-repellent coating of the present invention. For example... Figure 2 As shown, the coating in this embodiment not only has high light transmittance, but also the ability to absorb blue-violet light.

[0072] Figure 3 This invention relates to an anti-graffiti test of a high-hardness, transparent, fluorine-free liquid-repellent coating. For example... Figure 3 As shown, the coating in this embodiment exhibits excellent oil-resistant pen-drawing properties.

[0073] This method uses highly transparent, high mechanical strength, and low-cost organic polymers. By rationally designing the reaction of their functional groups, a cross-linking network was successfully constructed. After further regulation, a high-hardness (9H), transparent, liquid-repellent, fluorine-free, and environmentally friendly coating was successfully constructed. The preparation process is simple and easy to control, and has broad application prospects and excellent large-scale application value.

[0074] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made within the scope of the claims of the present invention should be included in the scope of the present invention.

Claims

1. A method for preparing a high-hardness, transparent, fluorine-free liquid-repellent coating, characterized in that: Includes the following steps: (1) Dissolve hydroxyl silicone oil, polyether modified silicone oil, epoxy resin, isocyanate derivative and melamine formaldehyde resin in an organic solvent to prepare a mixed solution; (2) The mixed solution is applied to a clean substrate and heated to cure, thereby obtaining the high-hardness, transparent, fluorine-free liquid-repellent coating. The mass ratio of hydroxyl silicone oil, polyether modified silicone oil, epoxy resin, isocyanate derivative and melamine-formaldehyde resin in step (1) is 0.045:0.018:0.5:0.8:0.5; The heating temperature in step (2) is 210 °C and the time is 0.5~3 h.

2. The method according to claim 1, characterized in that: The organic solvent mentioned in step (1) is an ester compound or a ketone compound.

3. The method according to claim 1, characterized in that: The hydroxyl silicone oil mentioned in step (1) is hydroxyl-terminated polydimethylsiloxane, the isocyanate derivative is hexamethylene diisocyanate trimer, and the melamine-formaldehyde resin is methyl etherified high imino melamine-formaldehyde resin.

4. The method according to claim 1, characterized in that: The coating method in step (2) is any one of drip coating, spin coating, or dip coating.

5. A high-hardness, transparent, fluorine-free liquid-repellent coating prepared by the method according to any one of claims 1-4.

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