Super-hydrophilic antifogging coating as well as preparation method and application thereof
The super hydrophilic anti-fog coating is prepared by mixing polyacrylate and epoxy silicone resin, which solves the problem of easy damage of the anti-fog coating and achieves high stability and improved anti-fog performance.
Patent Information
- Application Number
- CN202510917710.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-07-03
- Publication Date
- 2025-09-19
AI Technical Summary
Existing anti-fog coatings are easily damaged and have poor stability, and cannot effectively solve the turbidity problem caused by droplet condensation on the surface of transparent substrates.
A super-hydrophilic anti-fog coating is prepared by mixing polyacrylate and epoxy silicone resin through solution free radical copolymerization and hydrosilylation. Epoxy groups and polyethylene glycol side chains are introduced during the preparation process to enhance the molecular chain bonding and improve the coating stability.
The prepared anti-fog coating has good anti-fog performance and anti-protein adsorption function, which significantly improves the stability and mechanical properties of the coating.
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Figure CN120665490A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of coatings, and in particular to a super-hydrophilic anti-fog coating, a preparation method thereof and applications thereof. Background Art
[0002] Transparent substrates (such as glass) play an important role in daily life. Due to the high surface energy, when the surface temperature of the substrate is lower than the ambient water vapor dew point, droplet condensation will occur. These droplets will cause refraction and scattering of light, causing the transparent material to become turbid, which will lead to many problems and even cause serious harm. At present, there are two main methods to solve this problem: electric heating and anti-fog coating. Although the former method is effective, the inconvenience and energy consumption limit its widespread application. The other is to apply an anti-fog coating on the surface of the substrate. The superhydrophilic material can form a strong polarity or hydrogen bond with the water molecules, thereby effectively diffusing the droplets into a water film that does not scatter light. The surface can still remain optically transparent, but the water molecules will enter between the molecular chains of the superhydrophilic material, resulting in an increase in the spacing between the molecular chains of the superhydrophilic material and a weakening of the binding force between the molecular chains, which makes this type of anti-fog coating easily destroyed and has poor stability. Summary of the Invention
[0003] Based on this, it is necessary to provide a super hydrophilic anti-fog coating, a preparation method and application thereof to address the problems that existing anti-fog coatings are easily damaged and have poor stability.
[0004] A super hydrophilic anti-fog coating is prepared by mixing 40 to 68 parts of polyacrylate and 32 to 60 parts of epoxy silicone resin.
[0005] As a preferred solution, the polyacrylate is synthesized by solution free radical copolymerization using methyl methacrylate, butyl methacrylate and methacrylic acid as comonomers.
[0006] As a preferred solution, the epoxy silicone resin is synthesized by using hydrogenated silicone resin, allyl glycidyl ether and allyl polyethylene glycol as raw materials through a hydrosilylation method, and the epoxy silicone resin has epoxy groups and polyethylene glycol side chains on its surface.
[0007] A method for preparing the super-hydrophilic anti-fog coating as described above comprises the following steps:
[0008] S1, reacting a comonomer, a solvent, and an initiator under nitrogen protection and heat preservation to obtain a polymer solution, and adding diethyl ether dropwise to the polymer solution to obtain a polyacrylate;
[0009] S2, dissolving allyl glycidyl ether, allyl polyethylene glycol and a catalyst in a low-polarity solvent to obtain a solution A, dissolving a hydrogenated silicone resin in a low-polarity solvent to obtain a solution B, and adding the solution B dropwise to the solution A while maintaining the temperature. After the reaction is completed, an epoxy silicone resin is obtained;
[0010] S3. Evenly mix the polyacrylate obtained in S1 and the epoxy silicone resin obtained in S2 to obtain a super hydrophilic anti-fog coating.
[0011] As a preferred solution, the comonomer in S1 includes the following components in parts by weight: 60 parts of methyl methacrylate, 5 to 15 parts of methacrylic acid, and 20 to 35 parts of butyl methacrylate.
[0012] As a preferred embodiment, the solvent in S1 is an ethanol aqueous solution.
[0013] As a preferred solution, the mass ratio of the ethanol to the water is 25:8.
[0014] As a preferred solution, the mass of the ethanol aqueous solution is 1.65 to 3.3 times the total mass of the comonomers.
[0015] As a preferred embodiment, the initiator in S1 is azoisobutyronitrile.
[0016] As a preferred solution, the mass of the initiator is 0.5% to 4% of the total mass of the comonomers.
[0017] As a preferred solution, the mass of the initiator is 2.5% of the total mass of the comonomers.
[0018] As a preferred solution, the comonomer, solvent and initiator in S1 are reacted at a temperature of 70° C. to 75° C. for 4 to 5 hours to obtain a polymer solution.
[0019] As a preferred solution, in S1, diethyl ether is added dropwise to the polymer solution at a temperature below 30° C., and the solution is filtered and dried to obtain polyacrylate.
[0020] As a preferred embodiment, the mass ratio of the allyl glycidyl ether to the allyl polyethylene glycol in S2 is 2-10:1-3.
[0021] As a preferred embodiment, the catalyst is chloroplatinic acid.
[0022] As a preferred solution, the mass of the catalyst is 0.7% of the total mass of the allyl glycidyl ether and the allyl polyethylene glycol.
[0023] As a preferred method, the low-polarity solvent in S2 is toluene.
[0024] As a preferred solution, the hydrogen content of the hydrogen-containing silicone resin in S2 is 0.04 to 0.07 mol / g.
[0025] As a preferred solution, in S2, solution B is added dropwise to solution A at a temperature of 85°C.
[0026] As a preferred solution, after the reaction in S2 is completed, extraction is performed using toluene and aqueous solution to obtain epoxy silicone resin.
[0027] The super hydrophilic anti-fog coating prepared by the preparation method is coated on the surface of an optical or precision instrument and cured at high temperature to obtain an anti-fog coating.
[0028] As a preferred embodiment, the preparation method of the anti-fog coating comprises the following steps: applying the super-hydrophilic anti-fog coating prepared by the preparation method described above to the surface of an optical or precision instrument, and curing it at a temperature of 120° C. for 10 to 45 minutes to obtain an anti-fog coating.
[0029] As a preferred solution, the thickness of the anti-fog coating is ≤10 μm.
[0030] The present invention provides a super-hydrophilic anti-fog coating comprising a mixture of 40-68 parts polyacrylate and 32-60 parts epoxy silicone resin. The polyacrylate is synthesized via a solution free radical copolymerization method using high-hardness methyl methacrylate, highly flexible butyl methacrylate, and carboxyl-containing methacrylic acid as comonomers. The epoxy silicone resin, on the other hand, has epoxy groups and polyethylene glycol side chains on its surface. The hydrophobic butyl groups in the butyl methacrylate impart protein-resistance to the resulting anti-fog coating, while the polyethylene glycol side chains impart anti-fog properties. During the preparation of the anti-fog coating, the epoxy groups in the epoxy silicone resin react with the carboxyl groups in the polyacrylic acid, effectively enhancing the bonding between the molecular chains and improving the stability of the resulting anti-fog coating. Furthermore, the high strength and toughness of the epoxy silicone resin are utilized to improve the mechanical properties of the anti-fog coating. BRIEF DESCRIPTION OF THE DRAWINGS
[0031] Figure 1 This is a reaction synthesis diagram of the polyacrylate of the present invention;
[0032] Figure 2 This is a reaction synthesis diagram of the epoxy silicone resin of the present invention;
[0033] Figure 3 The effect of a water droplet being dropped on the anti-fog coating of the present invention at 0s and 5s;
[0034] Figure 4 Comparison of the protein adsorption resistance of blank glass beads (a, b) and glass beads with anti-fog coating (c, d) of the present invention;
[0035] Figure 5 2 is a comparison chart of the anti-fog effects of a blank glass slide (a) and a glass slide with an anti-fog coating (b) according to the present invention. DETAILED DESCRIPTION
[0036] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.
[0037] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.
[0038] A super hydrophilic anti-fog coating is prepared by mixing 40 to 68 parts of polyacrylate and 32 to 60 parts of epoxy silicone resin.
[0039] As a preferred solution, the polyacrylate is synthesized by solution free radical copolymerization using methyl methacrylate, butyl methacrylate and methacrylic acid as comonomers.
[0040] As a preferred solution, the epoxy silicone resin is synthesized by using hydrogenated silicone resin, allyl glycidyl ether and allyl polyethylene glycol as raw materials through a hydrosilylation method, and the epoxy silicone resin has epoxy groups and polyethylene glycol side chains on its surface.
[0041] A method for preparing the super-hydrophilic anti-fog coating as described above comprises the following steps:
[0042] S1, such as Figure 1 As shown, a comonomer, a solvent, and an initiator are reacted under nitrogen protection and heat preservation to obtain a polymer solution, and ether is added dropwise to the polymer solution to obtain a polyacrylate; wherein the comonomer comprises the following components in parts by weight: 60 parts of methyl methacrylate (MMA), 5 to 15 parts of methacrylic acid (MAA), and 20 to 35 parts of butyl methacrylate (BMA);
[0043] S2, such as Figure 2As shown, allyl glycidyl ether (AGE), allyl polyethylene glycol (APEG) and a catalyst are dissolved in a low-polarity solvent to obtain solution A, and hydrogenated silicone resin (HMQ) is dissolved in a low-polarity solvent to obtain solution B. Under heat preservation, solution B is added dropwise to solution A. After the reaction is completed, epoxy silicone resin is obtained; wherein m in allyl polyethylene glycol (APEG) is an integer of 4 to 30.
[0044] S3. Evenly mix the polyacrylate obtained in S1 and the epoxy silicone resin obtained in S2 to obtain a super hydrophilic anti-fog coating.
[0045] As a preferred embodiment, in S1, the solvent is an ethanol aqueous solution.
[0046] As a preferred solution, the mass ratio of the ethanol to the water is 25:8.
[0047] As a preferred solution, the mass of the ethanol aqueous solution is 1.65 to 3.3 times the total mass of the comonomers.
[0048] As a preferred embodiment, the initiator in S1 is azoisobutyronitrile (AIBN).
[0049] As a preferred solution, the mass of the initiator is 0.5% to 4% of the total mass of the comonomers.
[0050] As a preferred solution, the mass of the initiator is 2.5% of the total mass of the comonomers.
[0051] As a preferred solution, the comonomer, solvent and initiator in S1 are reacted at a temperature of 70° C. to 75° C. for 4 to 5 hours to obtain a polymer solution.
[0052] As a preferred solution, in S1, diethyl ether is added dropwise to the polymer solution at a temperature below 30° C., and the solution is filtered and dried to obtain polyacrylate.
[0053] As a preferred embodiment, the mass ratio of the allyl glycidyl ether to the allyl polyethylene glycol in S2 is 2-10:1-3.
[0054] As a preferred embodiment, the catalyst is chloroplatinic acid.
[0055] As a preferred solution, the mass of the catalyst is 0.7% of the total mass of the allyl glycidyl ether and the allyl polyethylene glycol.
[0056] As a preferred method, the low-polarity solvent in S2 is toluene.
[0057] As a preferred solution, the hydrogen content of the hydrogen-containing silicone resin in S2 is 0.04 to 0.07 mol / g.
[0058] As a preferred solution, in S2, solution B is added dropwise to solution A at a temperature of 85°C.
[0059] As a preferred solution, after the reaction in S2 is completed, extraction is performed using toluene and aqueous solution to obtain epoxy silicone resin.
[0060] The super hydrophilic anti-fog coating prepared by the preparation method is coated on the surface of an optical or precision instrument and cured at high temperature to obtain an anti-fog coating.
[0061] As a preferred embodiment, the preparation method of the anti-fog coating comprises the following steps: applying the super-hydrophilic anti-fog coating prepared by the preparation method described above to the surface of an optical or precision instrument, and curing it at a temperature of 120° C. for 10 to 45 minutes to obtain an anti-fog coating.
[0062] As a preferred solution, the thickness of the anti-fog coating is ≤10 μm.
[0063] The present invention provides a super-hydrophilic anti-fog coating comprising a mixture of 40-68 parts polyacrylate and 32-60 parts epoxy silicone resin. The polyacrylate is synthesized via a solution free radical copolymerization method using high-hardness methyl methacrylate, highly flexible butyl methacrylate, and carboxyl-containing methacrylic acid as comonomers. The epoxy silicone resin, on the other hand, has epoxy groups and polyethylene glycol side chains on its surface. The hydrophobic butyl groups in the butyl methacrylate impart protein-resistance to the resulting anti-fog coating, while the polyethylene glycol side chains render the resulting anti-fog coating hydrophilic and anti-fog. During the preparation of the anti-fog coating, the epoxy groups in the epoxy silicone resin react with the carboxyl groups in the polyacrylic acid, effectively enhancing the bonding between the molecular chains and improving the stability of the resulting anti-fog coating. Furthermore, the high strength and toughness of the epoxy silicone resin are utilized to improve the mechanical properties of the anti-fog coating.
[0064] Example 1
[0065] Preparation of super hydrophilic anti-fog coating
[0066] 1) 1g of methacrylic acid, 6g of methyl methacrylate, 3g of butyl methacrylate, 8g of water, 25g of ethanol, and 0.25g of azoisobutyronitrile were added to a 250mL three-necked flask. Mechanical stirring was started to thoroughly mix the components. Nitrogen was introduced for 15 minutes to remove oxygen from the flask. Under stirring and nitrogen protection, the temperature was raised to 70°C and the reaction was carried out for 4 hours to obtain a polymer solution. The reaction was stopped. When the temperature in the three-necked flask dropped below 30°C, the polymer solution was added dropwise to diethyl ether, filtered, and dried to obtain a polyacrylic acid resin.
[0067] 2) 4 g of allyl glycidyl ether, 6 g of allyl polyethylene glycol, and 0.07 g of chloroplatinic acid were dissolved in 40 g of toluene and added to a three-necked flask to obtain solution A. 10 g of a silicone resin having a hydrogen content of 0.07 mol was dissolved in 40 g of toluene to obtain solution B. Solution B was placed in a constant pressure funnel. After the temperature was raised to 85°C, solution B in the constant pressure funnel was slowly dripped into solution A in the three-necked flask. After a 6-hour addition reaction, the mixture was extracted with toluene and the aqueous solution to obtain an epoxy silicone resin.
[0068] 3) 1 g of polyacrylate was taken out and dissolved in anhydrous ethanol, 1.5 g of epoxy silicone resin was added, and mixed evenly to obtain a super hydrophilic anti-fog coating.
[0069] Preparation of anti-fog coating: The super hydrophilic anti-fog coating is evenly coated on a substrate (optical or precision instrument) and cured at a temperature of 120°C for 10 to 45 minutes to obtain an anti-fog coating with a thickness of ≤10 μm.
[0070] Example 2
[0071] Preparation of super hydrophilic anti-fog coating
[0072] 1) 1.5 g of methacrylic acid, 6 g of methyl methacrylate, 2.5 g of butyl methacrylate, 4 g of water, 12.5 g of ethanol, and 0.05 g of azoisobutyronitrile were added to a 250 mL three-necked flask. Mechanical stirring was initiated and the components were thoroughly mixed. Nitrogen was introduced for 15 minutes to remove oxygen from the flask. Under stirring and nitrogen protection, the temperature was raised to 75°C and the reaction was carried out for 4.5 hours to obtain a polymer solution. The reaction was stopped and the temperature in the three-necked flask dropped below 30°C. The polymer solution was then added dropwise to diethyl ether, filtered, and dried to obtain a polyacrylic acid resin.
[0073] 2) 10 g of allyl glycidyl ether, 3 g of allyl polyethylene glycol, and 0.091 g of chloroplatinic acid were dissolved in 40 g of toluene and added to a three-necked flask to obtain solution A. 10 g of a silicone resin having a hydrogen content of 0.05 mol was dissolved in 40 g of toluene to obtain solution B. Solution B was placed in a constant pressure funnel. After the temperature was raised to 85°C, solution B in the constant pressure funnel was slowly dripped into solution A in the three-necked flask. After a 6-hour addition reaction, the mixture was extracted with toluene and the aqueous solution to obtain an epoxy silicone resin.
[0074] 3) Take out 1 g of polyacrylate and dissolve it in anhydrous ethanol, add 1 g of epoxy silicone resin, and mix well to obtain a super hydrophilic anti-fog coating.
[0075] Preparation of anti-fog coating: The super hydrophilic anti-fog coating is evenly coated on a substrate (optical or precision instrument) and cured at a temperature of 120°C for 10 to 45 minutes to obtain an anti-fog coating with a thickness of ≤10 μm.
[0076] Example 3
[0077] Preparation of super hydrophilic anti-fog coating
[0078] 1) 0.5 g of methacrylic acid, 6 g of methyl methacrylate, 3.5 g of butyl methacrylate, 6.4 g of water, 20 g of ethanol, and 0.4 g of azoisobutyronitrile were added to a 250 mL three-necked flask. Mechanical stirring was initiated and the components were thoroughly mixed. Nitrogen was introduced for 15 minutes to remove oxygen from the flask. Under stirring and nitrogen protection, the temperature was raised to 73°C and the reaction was carried out for 5 hours to obtain a polymer solution. The reaction was then stopped. After the temperature in the three-necked flask dropped below 30°C, the polymer solution was added dropwise to diethyl ether, filtered, and dried to obtain a polyacrylic acid resin.
[0079] 2) 6 g of allyl glycidyl ether, 2 g of allyl polyethylene glycol, and 0.0056 g of chloroplatinic acid were dissolved in 40 g of toluene and added to a three-necked flask to obtain solution A. 10 g of a silicone resin having a hydrogen content of 0.04 mol was dissolved in 40 g of toluene to obtain solution B. Solution B was placed in a constant pressure funnel. After the temperature was raised to 85°C, solution B in the constant pressure funnel was slowly dripped into solution A in the three-necked flask. After a 6-hour addition reaction, the mixture was extracted with toluene and the aqueous solution to obtain an epoxy silicone resin.
[0080] 3) 1 g of polyacrylate was taken out and dissolved in anhydrous ethanol, 0.5 g of epoxy silicone resin was added, and mixed evenly to obtain a super hydrophilic anti-fog coating.
[0081] Preparation of anti-fog coating: The super hydrophilic anti-fog coating is evenly coated on a substrate (optical or precision instrument) and cured at a temperature of 120°C for 10 to 45 minutes to obtain an anti-fog coating with a thickness of ≤10 μm.
[0082] Test Example 1
[0083] Wetting performance test of anti-fog coating
[0084] Test method: drop a drop of water onto the anti-fog coating prepared in Example 1, and use a camera to take pictures at 0s and 5s after the water drop is dropped on the anti-fog coating. The results are as follows: Figure 3 shown.
[0085] Depend on Figure 3 It can be seen that the contact angle of the anti-fog coating prepared in Example 1 is 35±2°, which shows that the anti-fog coating has good hydrophilicity. The reason is that the polyethylene glycol side chain in the anti-fog coating can effectively improve the hydrophilicity of the anti-fog coating.
[0086] Test Example 2
[0087] Anti-protein adsorption function test of anti-fog coating
[0088] Test method: Bovine serum albumin labeled with fluorescein isothiocyanate (BSA-FITC) was used as the anti-adsorption property of the protein. First, the glass beads were evenly distributed on a glass slide, and the super hydrophilic anti-fog coating prepared by Example 1 was coated on its surface. Subsequently, the glass slide was placed in an oven at 120°C for curing to obtain glass beads with an anti-fog coating. Under light-proof conditions, the glass beads with anti-fog coating and blank glass beads were infiltrated with 0.1 mg / mL BSA-FITC and incubated at 25°C for 30 minutes respectively. Subsequently, the glass beads were extracted and washed three times with phosphate buffer solution (PBS solution, pH 7.4) to remove excess non-adherent proteins. Subsequently, the glass slide was irradiated with a laser of λ=385nm, and the residual fluorescence intensity on the coating surface was observed using a fluorescence inverted microscope (Ts2R-F-AFL, Japan). The results are shown as follows. Figure 4 shown.
[0089] Depend on Figure 4 It can be seen that the remaining fluorescence intensity of the glass beads with the anti-fog coating is 99% lower than that of the blank glass beads, which shows that the anti-fog coating has anti-protein adsorption performance.
[0090] Test Example 3
[0091] Anti-fog performance test of anti-fog coating
[0092] Test method: Place the glass slide coated with the super hydrophilic anti-fog coating prepared in Example 1 in an oven at 120°C for curing to obtain a glass slide with an anti-fog coating; place the glass slide with the anti-fog coating and a blank glass slide 50 mm above hot water for 15 seconds, and take a photo of the substrate immediately after exposure. The results are as follows: Figure 5 shown.
[0093] Depend on Figure 5 It can be seen that the glass slide with the anti-fog coating has no fog deposition, while the blank glass slide has fog deposition, which shows that the anti-fog coating has good anti-fog performance.
[0094] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.
[0095] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.
Claims
1. A super hydrophilic anti-fog coating, characterized in that: It is prepared by mixing 40 to 68 parts of polyacrylate and 32 to 60 parts of epoxy silicone resin.
2. The super hydrophilic anti-fog coating according to claim 1, characterized in that The polyacrylate is synthesized by solution free radical copolymerization using methyl methacrylate, butyl methacrylate and methacrylic acid as comonomers.
3. The super hydrophilic anti-fog coating according to claim 1, characterized in that: The epoxy silicone resin is synthesized by using hydrogenated silicone resin, allyl glycidyl ether and allyl polyethylene glycol as raw materials through a hydrosilylation method. The epoxy silicone resin has epoxy groups and polyethylene glycol side chains on its surface.
4. A method for preparing a super hydrophilic anti-fog coating according to claim 1-3, characterized in that: The following steps are involved: S1, reacting a comonomer, a solvent, and an initiator under nitrogen protection and heat preservation to obtain a polymer solution, and adding diethyl ether dropwise to the polymer solution to obtain a polyacrylate; S2, dissolving allyl glycidyl ether, allyl polyethylene glycol and a catalyst in a low-polarity solvent to obtain a solution A, dissolving a hydrogenated silicone resin in a low-polarity solvent to obtain a solution B, and adding the solution B dropwise to the solution A while maintaining the temperature. After the reaction is completed, an epoxy silicone resin is obtained; S3. Evenly mix the polyacrylate obtained in S1 and the epoxy silicone resin obtained in S2 to obtain a super hydrophilic anti-fog coating.
5. The method for preparing a super hydrophilic anti-fog coating according to claim 4, wherein: The comonomers in S1 include the following components in parts by weight: 60 parts of methyl methacrylate, 5 to 15 parts of methacrylic acid, and 20 to 35 parts of butyl methacrylate.
6. The method for preparing a super hydrophilic anti-fog coating according to claim 4, wherein: The solvent in S1 is an ethanol aqueous solution, and the mass ratio of the ethanol to the water is 25:8; the mass of the ethanol aqueous solution is 1.65 to 3.3 times the total mass of the comonomer.
7. The method for preparing a super hydrophilic anti-fog coating according to claim 4, wherein: The initiator in S1 is azoisobutyronitrile, and the mass of the initiator is 0.5-4% of the total mass of the comonomers.
8. The method for preparing a super hydrophilic anti-fog coating according to claim 4, wherein: The mass ratio of the allyl glycidyl ether to the allyl polyethylene glycol in S2 is 2-10:1-3.
9. The method for preparing a super hydrophilic anti-fog coating according to claim 4, wherein: The catalyst is chloroplatinic acid, and the mass of the catalyst is 0.7% of the total mass of the allyl glycidyl ether and the allyl polyethylene glycol.
10. A super hydrophilic anti-fog coating prepared by the preparation method according to any one of claims 4 to 9 is applied to the surface of an optical or precision instrument and cured at high temperature to obtain an anti-fog coating.