Fluorine-containing coating for super-weather-resistant wrapping tape and preparation method thereof

Abstract

The present application relates to the technical field of fluorine-containing coating, in particular to a kind of fluorine-containing coating for super weathering winding adhesive tape and preparation method thereof, it is composed of the following mass parts of component: hyperbranched perfluoropolyether diol 45-55 parts, ethyl silicate 12-13 parts, hexamethylene diisocyanate trimer 30-40 parts and other raw materials;The present application is synergized by designing gradient distribution fluorocarbon skeleton and organic-inorganic hybrid network, combined with surface modified nano reinforced particles, the coating constructs directional protective barrier at molecular level, significantly improves interface stability through multistage bonding mechanism, and utilizes the synergistic effect of nano phase and matrix to enhance the durability of the body, so that the product is doubled in extreme environment Weathering is extended, while flexibility and surface self-cleaning function are considered, and has wide application prospect in the field of winding protection in harsh working conditions such as marine engineering and energy pipeline.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of fluorine-containing coating, in particular to a fluorine-containing coating for super-weather-resistant wrapping tape and a preparation method thereof. BACKGROUND

[0002] As a corrosion-proof sealing material for major infrastructures such as oil pipelines and offshore wind power facilities, wrapping tape is subjected to ultraviolet radiation, salt spray corrosion and mechanical stress cycles for a long time. The long-term stability of the surface coating in extreme environments becomes a core indicator of the protection life. Fluorine-containing coatings are considered an ideal choice for achieving super-weather resistance due to the excellent ultraviolet aging resistance and chemical inertness conferred by the high bond energy of the C-F bond.

[0003] In the prior art, although the coating based on linear polyvinylidene fluoride or fluorine-olefin copolymer has basic weather resistance, the uniform distribution of fluorine elements leads to insufficient surface energy regulation, which cannot effectively block acid rain penetration. Meanwhile, the modulus mismatch between the rigid fluorocarbon chain and the flexible tape substrate easily causes interface peeling under dynamic winding stress. In addition, unmodified nanoparticles are introduced to enhance hardness, but they have poor compatibility with fluororesin, which leads to stress concentration points caused by the aggregation of the dispersed phase and accelerates the expansion of micro-cracks under ultraviolet aging.

[0004] Therefore, according to the related technology in the above, it is urgent to develop a fluorine-containing coating for super-weather-resistant wrapping tape and a preparation method thereof. SUMMARY

[0005] Therefore, the present application aims to provide a fluorine-containing coating for super-weather-resistant wrapping tape and a preparation method thereof to solve the problems of insufficient hydrophobicity of fluorine-containing coatings, peeling caused by rigid-flexible interface mismatch, and defects in nano-dispersion stability in the prior art.

[0006] To achieve the above purpose, the present application provides a fluorine-containing coating for super-weather-resistant wrapping tape and a preparation method thereof.

[0007] A fluorine-containing coating for super-weather-resistant wrapping tape is composed of the following components by mass: hyperbranched perfluoropolyether diol 45-55 parts, tetraethyl orthosilicate 12-13 parts, hexamethylene diisocyanate trimer 30-40 parts, modified nano-silicon dioxide 4-6 parts, catalyst dibutyltin dilaurate 0.5-1 part, and leveling agent BYK-381 0.4-0.6 part.

[0008] The modified nano-silicon dioxide is perfluorooctyltriethoxysilane modified nano-silicon dioxide.

[0009] Preferably, the preparation steps of the hyperbranched perfluoropolyether diol are as follows:

[0010] Step A1: under nitrogen atmosphere, the perfluoropolyether diol was added into tetrahydrofuran solution, stirred to dissolve, heated to 50-70℃, glycidyl methacrylate and triethylamine were added, reacted for 5-7h, the reaction was completed, cooled to 20-30℃, distilled under reduced pressure, to obtain the epoxy-terminated perfluoropolyether diol;

[0011] Step A2: under nitrogen atmosphere, the epoxy-terminated perfluoropolyether diol was added into tetrahydrofuran solution, stirred to dissolve, hydroxyethyl acrylate and initiator azobisisobutyronitrile were added, heated to 60-80℃, reacted for 7-9h, the reaction was completed, to obtain the reaction liquid;

[0012] Step A3: the reaction liquid was added into deionized water, stirred to mix, catalyst triethylamine was added, heated to 90-110℃, refluxed for 3-5h, the reaction was completed, cooled to 20-30℃, washed and dried, distilled under reduced pressure, to obtain the hyperbranched perfluoropolyether diol;

[0013] The hyperbranched perfluoropolyether diol was constructed by epoxy-acrylate cascade reaction to form a three-dimensional network, and the terminal perfluoroalkyl chain migrated to the surface of the coating during curing, and simultaneously condensed with the silicon hydroxyl generated by hydrolysis of tetraethyl orthosilicate to form a covalent bond, so that the fluorine chain was stably anchored at the inorganic-organic interface.

[0014] Preferably, the mass ratio of the perfluoropolyether diol, glycidyl methacrylate and triethylamine in step A1 was 1:0.2-0.24:0.014-0.016.

[0015] Preferably, the mass ratio of the epoxy-terminated perfluoropolyether diol, hydroxyethyl acrylate and initiator in step A2 was 1:0.48-0.52:0.008-0.012.

[0016] Preferably, the mass ratio of the reaction liquid and catalyst in step A3 was 1:0.004-0.006.

[0017] Preferably, the preparation steps of the modified nanosilica were as follows:

[0018] Step B1: under nitrogen atmosphere, the perfluorooctyltriethoxysilane was added into anhydrous ethanol, deionized water was added, heated to 20-30℃, and hydrolyzed for 20-40min to obtain the hydrolysis liquid;

[0019] Step B2: the nanosilica was added into anhydrous ethanol, ultrasonically treated for 20-40min at a power of 400-600W, the hydrolysis liquid was added, heated to 50-70℃, stirred to react for 7-9h at a speed of 500-700rpm, acetic acid was added to adjust the pH to 5-6, the reaction was completed, washed and dried in vacuum to obtain the modified silica;

[0020] The nano-silica is modified by perfluorooctyl silane, the surface of which is grafted with perfluoroalkyl long chain, the nano-particle of which is embedded in hybrid network, the hardness of which is improved, the compatibility of which with hyperbranched perfluoropolyether diol segment is optimized, the agglomeration of which is avoided, and the surface fluorine chain of which forms a super-low surface energy layer with hyperbranched perfluoropolyether diol, increasing the hydrophobicity;

[0021] Preferably, the mass ratio of perfluorooctyl triethoxysilane to deionized water in step B1 is 1:0.15-0.17.

[0022] Preferably, the mass ratio of nano-silica, anhydrous ethanol and hydrolyzate in step B2 is 1:15.6-16:8-8.4.

[0023] A preparation method of a fluorine-containing coating for super-weather-resistant wrapping tape, the preparation steps are as follows:

[0024] Step S1: tetraethyl orthosilicate and 0.1 mol / L hydrochloric acid aqueous solution are added to propylene glycol methyl ether acetate solvent, heated to 50-70℃, reacted for 1.5-2.5h, rotation speed 400-600rpm, to obtain transparent sol;

[0025] Step S2: hyperbranched perfluoropolyether diol and transparent sol are added to propylene glycol methyl ether acetate solvent, heated to 70-90℃, stirred and reacted for 2-4h, rotation speed 300-500rpm, reaction is completed, to obtain prepolymer;

[0026] Step S3: modified nano-silica is added to the prepolymer, heated to 30-40℃, ultrasonic treated for 20-40min, power 400-600W, placed in a high-speed homogenizer, reacted for 50-70min, rotation speed 1800-2200rpm, added leveling agent, stirred for 10-20min, rotation speed reduced to 150-250rpm, added hexamethylene diisocyanate trimer and catalyst dibutyltin dilaurate, stirred for 10-20min, rotation speed increased to 700-900rpm, to obtain fluorine-containing coating;

[0027] Tetraethyl orthosilicate is hydrolyzed to silica sol under acid catalysis, and the hydroxyl group of hyperbranched perfluoropolyether diol is condensed to form Si-O-C / F interpenetrating network, and the inorganic Si-O bond resists ultraviolet degradation and the organic fluorine chain blocks chemical corrosion medium.

[0028] Preferably, the mass ratio of tetraethyl orthosilicate to hydrochloric acid aqueous solution in step S1 is 1:0.07-0.09;

[0029] The mass ratio of hyperbranched perfluoropolyether diol to transparent sol in step S2 is 1.7-1.8:1;

[0030] The mass ratio of the modified nanosilica, the prepolymer, the leveling agent, the hexamethylene diisocyanate trimer and the catalyst in step S3 is 0.028-0.032:1:0.0028-0.0032:0.21-0.23:0.004-0.006.

[0031] Advantages of the present application:

[0032] The present application provides a kind of fluorine-containing paint for super weathering winding adhesive tape, the present application is through the gradient distribution of fluorocarbon skeleton and organic-inorganic hybrid network synergistic effect design, combined with surface modified nano reinforcing particle, realized the innovation breakthrough of material structure.Compared with prior art, the coating constructs directional protective barrier at molecular level, significantly improves interface stability through multi-level bonding mechanism, and uses the synergistic effect of nanophase and matrix to enhance the durability of the body, so that the product is doubled in extreme environment, while considering flexibility and surface self-cleaning function, it has wide application prospect in the field of winding protection in harsh working conditions such as marine engineering and energy pipeline. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical scheme and advantages of the present application more clear and obvious, the present application is further described in detail below with specific examples.

[0034] Example 1: The preparation steps of hyperbranched perfluoropolyether diol are as follows:

[0035] S1: Under nitrogen atmosphere, 100g of perfluoropolyether diol was added to 200mL of tetrahydrofuran solution, stirred and dissolved, heated to 50℃, 20g of glycidyl methacrylate and 1.4g of triethylamine were added, reacted for 7h, cooled to 20℃, and distilled under reduced pressure to obtain epoxy-terminated perfluoropolyether diol;

[0036] S2: Under nitrogen atmosphere, 100g of epoxy-terminated perfluoropolyether diol was added to 200mL of tetrahydrofuran solvent, stirred and dissolved, 48g of hydroxyethyl acrylate and 0.8g of initiator azobisisobutyronitrile were added, heated to 60℃, reacted for 9h, and the reaction was completed to obtain a reaction liquid;

[0037] S3: 100g of the reaction liquid was added to 100mL of deionized water, stirred and mixed, 0.4g of catalyst triethylamine was added, heated to 90℃, refluxed for 5h, the reaction was completed, cooled to 20℃, separated and washed, dried, and distilled under reduced pressure to obtain hyperbranched perfluoropolyether diol.

[0038] Example 2: The preparation steps of hyperbranched perfluoropolyether diol are as follows:

[0039] S1: 100 g of perfluoropolyether diol was added to 200 mL of tetrahydrofuran solution under a nitrogen atmosphere, stirred and dissolved, warmed to 60℃, 22 g of glycidyl methacrylate and 1.5 g of triethylamine were added, reacted for 6 h, the reaction was completed, cooled to 25℃, and distilled under reduced pressure to obtain an epoxy-terminated perfluoropolyether diol;

[0040] S2: 100 g of epoxy-terminated perfluoropolyether diol was added to 200 mL of tetrahydrofuran solvent under a nitrogen atmosphere, stirred and dissolved, 50 g of hydroxyethyl acrylate and 1 g of initiator azobisisobutyronitrile were added, warmed to 70℃, reacted for 8 h, the reaction was completed, and a reaction liquid was obtained;

[0041] S3: 100 g of the reaction liquid was added to 100 mL of deionized water, stirred and mixed, 0.5 g of catalyst triethylamine was added, warmed to 100℃, refluxed for 4 h, the reaction was completed, cooled to 25℃, separated and washed, dried, and distilled under reduced pressure to obtain hyperbranched perfluoropolyether diol.

[0042] Example 3: The preparation steps of hyperbranched perfluoropolyether diol are as follows:

[0043] S1: 100 g of perfluoropolyether diol was added to 200 mL of tetrahydrofuran solution under a nitrogen atmosphere, stirred and dissolved, warmed to 70℃, 24 g of glycidyl methacrylate and 1.6 g of triethylamine were added, reacted for 5 h, the reaction was completed, cooled to 30℃, and distilled under reduced pressure to obtain an epoxy-terminated perfluoropolyether diol;

[0044] S2: 100 g of epoxy-terminated perfluoropolyether diol was added to 200 mL of tetrahydrofuran solvent under a nitrogen atmosphere, stirred and dissolved, 52 g of hydroxyethyl acrylate and 1.2 g of initiator azobisisobutyronitrile were added, warmed to 80℃, reacted for 7 h, the reaction was completed, and a reaction liquid was obtained;

[0045] S3: 100 g of the reaction liquid was added to 100 mL of deionized water, stirred and mixed, 0.6 g of catalyst triethylamine was added, warmed to 110℃, refluxed for 3 h, the reaction was completed, cooled to 30℃, separated and washed, dried, and distilled under reduced pressure to obtain hyperbranched perfluoropolyether diol.

[0046] Example 4: The preparation steps of modified nano-silica are as follows:

[0047] S1: 100 g of perfluorooctyltriethoxysilane was added to 200 mL of anhydrous ethanol under a nitrogen atmosphere, 15 g of deionized water was added, warmed to 20℃, and stirred and hydrolyzed for 40 min to obtain a hydrolysis liquid;

[0048] S2: Add 10g of nano-silica to 156g of anhydrous ethanol, sonicate for 20min at 600W, add 80g of hydrolysate, heat to 50℃, stir for 9h at 500rpm, add acetic acid, adjust pH to 5-6, after the reaction is complete, centrifuge, wash, and vacuum dry to obtain modified silica.

[0049] Example 5: The preparation steps of modified nano-silica are as follows:

[0050] S1: Under a nitrogen atmosphere, 100g of perfluorooctyltriethoxysilane was added to 200mL of anhydrous ethanol, 16g of deionized water was added, the temperature was raised to 25℃, and the mixture was stirred and hydrolyzed for 30min to obtain the hydrolysate.

[0051] S2: Add 10g of nano-silica to 158g of anhydrous ethanol, sonicate for 30min at 500W, add 82g of hydrolysate, heat to 60℃, stir for 8h at 600rpm, add acetic acid, adjust pH to 5-6, after the reaction is complete, centrifuge, wash, and vacuum dry to obtain modified silica.

[0052] Example 6: The preparation steps of modified nano-silica are as follows:

[0053] S1: Under a nitrogen atmosphere, 100g of perfluorooctyltriethoxysilane was added to 200mL of anhydrous ethanol, 17g of deionized water was added, the temperature was raised to 30℃, and the mixture was stirred and hydrolyzed for 20min to obtain the hydrolysate.

[0054] S2: Add 10g of nano-silica to 160g of anhydrous ethanol, sonicate for 40min at 400W, add 84g of hydrolysate, heat to 70℃, stir for 7h at 700rpm, add acetic acid, adjust pH to 5-6, after the reaction is complete, centrifuge, wash, and vacuum dry to obtain modified silica.

[0055] Example 7: A method for preparing a fluorinated coating for ultra-weather-resistant wrapping tape:

[0056] S1: Add 100g of tetraethyl orthosilicate and 7g of 0.1mol / L hydrochloric acid aqueous solution to 200mL of propylene glycol methyl ether acetate solvent, heat to 50℃, react for 2.5h, and rotate at 400rpm to obtain a transparent sol.

[0057] S2: Add 170g of hyperbranched perfluoropolyether glycol (Example 1) and 100g of transparent sol to 300mL of propylene glycol methyl ether acetate solvent, heat to 70℃, stir for 4h at 300rpm, and the reaction is complete to obtain the prepolymer.

[0058] S3: 2.8 g of modified nanosilica (Example 4) was added to 100 g of prepolymer, warmed to 30°C, ultrasonic treatment for 40 min, power 400 W, placed in a high-speed homogenizer, reacted for 70 min, speed 1800 rpm, 0.28 g of leveling agent was added, stirring for 20 min, speed reduced to 150 rpm, 21 g of hexamethylene diisocyanate trimer and 0.4 g of catalyst dibutyltin dilaurate were added, stirring for 20 min, speed increased to 700 rpm, to obtain a fluorine-containing coating.

[0059] Example 8: A preparation method of a fluorine-containing coating for an ultra-weather-resistant wrapping tape:

[0060] S1: 100 g of tetraethyl orthosilicate, 8 g of 0.1 mol / L hydrochloric acid aqueous solution were added to 200 mL of propylene glycol methyl ether acetate solvent, warmed to 60°C, reacted for 2 h, speed 500 rpm, to obtain a transparent sol;

[0061] S2: 175 g of hyperbranched perfluoropolyether diol (Example 2) and 100 g of transparent sol were added to 300 mL of propylene glycol methyl ether acetate solvent, warmed to 80°C, stirred for 3 h, speed 400 rpm, the reaction was completed, to obtain a prepolymer;

[0062] S3: 3 g of modified nanosilica (Example 5) was added to 100 g of prepolymer, warmed to 35°C, ultrasonic treatment for 30 min, power 500 W, placed in a high-speed homogenizer, reacted for 60 min, speed 2000 rpm, 0.3 g of leveling agent was added, stirring for 15 min, speed reduced to 200 rpm, 22 g of hexamethylene diisocyanate trimer and 0.5 g of catalyst dibutyltin dilaurate were added, stirring for 15 min, speed increased to 800 rpm, to obtain a fluorine-containing coating.

[0063] Example 9: A preparation method of a fluorine-containing coating for an ultra-weather-resistant wrapping tape:

[0064] S1: 100 g of tetraethyl orthosilicate, 9 g of 0.1 mol / L hydrochloric acid aqueous solution were added to 200 mL of propylene glycol methyl ether acetate solvent, warmed to 70°C, reacted for 1.5 h, speed 600 rpm, to obtain a transparent sol;

[0065] S2: 180 g of hyperbranched perfluoropolyether diol (Example 3) and 100 g of transparent sol were added to 300 mL of propylene glycol methyl ether acetate solvent, warmed to 90°C, stirred for 2 h, speed 500 rpm, the reaction was completed, to obtain a prepolymer;

[0066] S3: 3.2 g of modified nano-silica (Example 6) was added into 100 g of prepolymer, heated to 40 °C, ultrasonic treatment for 20 min, power 600 W, placed in a high-speed homogenizer, reaction for 50 min, speed 2200 rpm, 0.32 g of leveling agent was added, stirring for 10 min, the speed was reduced to 250 rpm, 23 g of hexamethylene diisocyanate trimer and 0.6 g of catalyst dibutyltin dilaurate were added, stirring for 20 min, the speed was increased to 700 rpm, and a fluorine-containing coating was obtained.

[0067] Example 10: A method for preparing a fluorine-containing coating for super-weather-resistant wrapping tape

[0068] The fluorine-containing coating (Example 7) was scraped onto the tape substrate with a coater, with a film thickness of 30 μm, and placed in an oven, heated to 70 °C, baked for 12 min, then heated to 130 °C, baked for 15 min, to obtain a fluorine-containing coating.

[0069] Example 11: A method for preparing a fluorine-containing coating for super-weather-resistant wrapping tape

[0070] The fluorine-containing coating (Example 8) was scraped onto the tape substrate with a coater, with a film thickness of 30 μm, and placed in an oven, heated to 80 °C, baked for 10 min, then heated to 120 °C, baked for 20 min, to obtain a fluorine-containing coating.

[0071] Example 12: A method for preparing a fluorine-containing coating for super-weather-resistant wrapping tape

[0072] The fluorine-containing coating (Example 9) was scraped onto the tape substrate with a coater, with a film thickness of 30 μm, and placed in an oven, heated to 90 °C, baked for 8 min, then heated to 110 °C, baked for 25 min, to obtain a fluorine-containing coating.

[0073] Comparative Example 1:

[0074] This comparative example differs from Example 10 in that the process for preparing a fluorine-containing coating for super-weather-resistant wrapping tape is changed from "heated to 70 °C, baked for 12 min, then heated to 130 °C, baked for 15 min" to "heated to 120 °C and baked for 30 min", and the remaining steps and parameters are the same. This comparative example will not be repeated, and a fluorine-containing coating is ultimately obtained.

[0075] Comparative Example 2:

[0076] This comparative example differs from Example 10 in that the "hyperbranched perfluoropolyether diol" is replaced with "linear polyvinylidene fluoride", and the remaining steps and parameters are the same. This comparative example will not be repeated, and a fluorine-containing coating is ultimately obtained.

[0077] Comparative Example 3:

[0078] The comparative example is compared with example 10 only by replacing "modified nano-silica" with "hydrophilic nano-silica", and the rest of the steps and parameters are the same. The comparative example will not be repeated here. Finally, a fluorine-containing coating is obtained.

[0079] Comparative Example 4:

[0080] The comparative example is compared with example 10 only by replacing "modified nano-silica" with "hydrophilic nano-silica", and the rest of the steps and parameters are the same. The comparative example will not be repeated here. Finally, a fluorine-containing coating is obtained.

[0081] Performance test:

[0082] UV aging resistance test:

[0083] According to the test standard of ISO 4892-3, use UV aging box, 60° gloss meter and spectrophotometer;

[0084] 1. Take 5.0g of each of examples 10-12 and comparative examples 1-4, and place them in a constant temperature box with a temperature of 23±2℃ and RH of 50±5%, and maintain for 168h;

[0085] 2. Take out the sample and place it in a UV aging box with a wavelength of 340nm and an irradiance of 0.76±0.02W / m 2 , light stage, temperature 60±3℃, lasting 4h, condensation stage, temperature 50±3℃, lasting 4h, cycle 240h, take out the sample and detect its gloss loss rate and color difference with 60° gloss meter and spectrophotometer respectively;

[0086] 3. Gloss loss calculation formula: , G0: 60° gloss value of the sample before testing, G1: 60° gloss value of the sample after testing;

[0087] 4. Color difference calculation formula:

[0088] , L1, a1, b1: measured sample after aging, L0, a0, b0: measured sample before aging.

[0089] Table 1 UV aging resistance test results

[0090]

[0091] Mechanical property test

[0092] Abrasion resistance test

[0093] According to the test standard of GB / T23988-2009, use sand falling abrasion tester;

[0094] 1. Take 25mm diameter standard sand from Examples 10-12 and Comparative Examples 1-4 respectively, fix it at an angle of 45° below the sand flow impact point, drop distance 1m, sand flow rate 16.5±0.5g, and total mass 2000g standard sand into the funnel, freely impact the coating surface, and weigh the coating mass M1 after impact.

[0095] 2. Formula for calculating mass loss per unit area: A: Area of ​​the worn region (cm²) 2 ).

[0096] Flexibility test

[0097] The test was conducted using a tapered shaft bending tester in accordance with the GB / T 6742-2007 standard.

[0098] 1. Take samples from Examples 10-12 and Comparative Examples 1-4 respectively, cut them into 150mm×50mm pieces, bend the samples 180° along the minimum axial diameter 2T, test 1T if there is no cracking, test 3T if there is cracking, and find only the minimum T value without cracking.

[0099] 2. Result judgment: 0T: No cracking when folded directly (0° bend), 1T: No cracking when bent around an axis with 1 times the thickness, 2T: No cracking when bent around an axis with 2 times the thickness. Note: 1T is the best grade, proving excellent flexibility.

[0100] Adhesion test

[0101] Referring to the ISO 2409 cross-cut test standard, samples from Examples 10-12 and Comparative Examples 1-4, each 100mm × 100mm in size, were used. A knife was used to make 6 × 6 1mm cuts perpendicular to the sample surface. 2 Clean up any debris from the grid area, apply tape tightly to the grid area, and after 60 seconds, peel it off at a uniform speed at a 60° angle. Observe the degree of detachment. The rating standard is 0-5, with 0-1 being acceptable.

[0102] Table 2 Mechanical property test results of the examples and comparative examples

[0103]

[0104] Hydrophobicity test

[0105] Contact angle test

[0106] A JC2000D1 contact angle meter was used, and the test solution was ultrapure deionized water;

[0107] 1. Take the fluorinated coatings of Examples 7-9 and Comparative Examples 1-4 respectively, and apply them evenly to a 50mm×50mm butyl rubber substrate. After gradient curing, cure for 168 hours. Before testing, clean the surface with anhydrous ethanol and nitrogen to avoid fingerprint contamination.

[0108] 2、 Microsyringe drop 5 μL water droplet vertically on sample surface, the droplet free-fall 5 mm from the surface, take the average value of left and right contact angle, θ > 150° is superhydrophobic.

[0109] Roll-off angle test

[0110] Using a tilt platform instrument;

[0111] 1、 Take the fluorine-containing coatings of Examples 7-9 and Comparative Examples 1-4, evenly blade-coat on 50 mm x 50 mm butyl rubber substrates, gradiently cure and maintain for 168 h, clean the surface with anhydrous ethanol and nitrogen blowing before testing to avoid fingerprint pollution;

[0112] 2、 Fix the sample horizontally on the platform, drop 10 μL water droplet on the surface, tilt the platform at a uniform speed of 1° / s, and record the tilt angle α when the water droplet first rolls off.

[0113] Table 3 Hydrophobicity test results of examples and comparative examples

[0114]

[0115] “*” Note: Roll-off angle > 90° indicates that the water droplet does not roll off but spreads directly, recorded as > 90*.

[0116] Chemical resistance:

[0117] According to the test standard of ISO 9227-2017, use a cyclic salt spray chamber, 5.0 ± 0.5% NaCl solution;

[0118] 1、 Take the samples of Examples 10-12 and Comparative Examples 1-4 respectively, size 150 mm x 100 mm, use a 30° blade angle tool to draw two intersecting lines on the coating surface, 50 mm long, deep to the substrate, angle 60°, place the sample at an angle of 20 ± 5° to the vertical direction in the cyclic salt spray chamber, sedimentation 1.5 mL, 80 cm 2 / h, after taking out the sample, rinse with deionized water, dry at room temperature for 24 h;

[0119] 2、 Calculation formula: , W0: initial scratch width, W1: maximum corrosion expansion width after corrosion.

[0120] Acid resistance test

[0121] According to the test standard of ISO 9227-2017, 10.0 ± 0.5% H2SO4 solution;

[0122] 1. Take 5.0 g of the samples of Examples 10-12 and Comparative Examples 1-4, respectively, dry the samples in an oven at 50℃ for 2 h, weigh m0 after cooling, immerse the samples in acid liquid, update the acid liquid every 24 h, take out the samples, rinse with deionized water, absorb surface moisture with filter paper, dry at 50℃ for 2 h, weigh m1 after cooling;

[0123] 2. Calculation formula:

[0124] Table 4 Test results of chemical resistance of examples and comparative examples

[0125]

[0126] Data analysis:

[0127] As can be seen from Tables 1-4, the fluorine-containing coating for super-weather-resistant wrapping tape prepared by the application has more excellent ultraviolet aging resistance, mechanical properties, super-hydrophobicity and chemical resistance;

[0128] Comparative Example 1, because the “temperature is raised to 70℃, baked for 12 min, then raised to 130℃, baked for 15 min” in the preparation process of the fluorine-containing coating for super-weather-resistant wrapping tape is deleted and replaced with “temperature is raised to 120℃ and baked for 30 min”, the gloss loss and etching width increase significantly, the flexibility and adhesion decrease, and the hydrophobicity is poor. The reason is that the silicon hydroxyl groups generated by the hydrolysis of tetraethyl orthosilicate need to be gradually condensed with the hydroxyl groups of the hyperbranched perfluoropolyether diol at low temperature to form Si-O-C covalent bonds and construct an inorganic-organic interpenetrating network skeleton. The high temperature triggers the directional migration of perfluoroalkyl chains to the surface of the coating to form a dense fluorocarbon barrier. However, the constant temperature of 120℃ makes the condensation of the silica sol too fast, and the migration of the fluorine chain lags behind, resulting in incomplete bonding of the inorganic phase (Si-O) and the organic phase (C-F) at the interface, and enrichment of fluorine elements inside the coating, which reduces the surface concentration and the hydrophobicity. In addition, the single temperature of 120℃ makes the high-polarity silica sol network form preferentially, physically blocking the migration path of the fluorine chain, and the fluorine chain is “locked” inside the coating, unable to form a low-surface-energy layer. At the same time, the simultaneous rapid curing of the substrate and the coating at 120℃ causes shear stress concentration at the interface, and the difference in shrinkage after cooling causes microcracks;

[0129] Comparative Example 2, because the linear polyvinylidene fluoride is replaced by a hyperbranched fluorine ether, the wear resistance and ultraviolet resistance are poor, the hydrophobicity is insufficient, and the flexibility is reduced. The reason is that the linear polymer lacks a three-dimensional network of hyperbranched structure, resulting in uneven distribution of fluorine elements, failure of surface energy regulation, mismatch of rigid chain segments and tape substrate modulus, easy peeling under dynamic stress, and stress concentration caused by poor dispersion of nanoparticles;

[0130] Comparative Example 3, due to the replacement of modified nano-silica with hydrophilic nano-silica, results in weaker acid resistance and hydrophobicity than the examples, and the etching width increases, the reason is that the unmodified nano-particle surface hydrophilic group has poor compatibility with fluororesin, leading to agglomeration, and the synergistic effect of the absence of perfluoroalkyl chain cannot form an ultra-low surface energy layer, and the acid liquid easily penetrates and erodes the interface;

[0131] Comparative Example 4, due to the replacement of tetraethyl orthosilicate with silane coupling agent KH-560, results in increased gloss loss and increased etching width, the reason is that tetraethyl orthosilicate is hydrolyzed to silica sol under acidic conditions, and condensation reaction occurs with the hydroxyl groups of hyperbranched fluorine ether to form a three-dimensional Si-O-C / F covalent network, while KH-560 as an epoxy silane coupling agent, the epoxy group preferentially ring-opening reaction with fluorine ether hydroxyl group, consumes bonding sites, and the residual methoxy group hydrolyzes to form isolated =Si-OH, which cannot be extended to a continuous inorganic network, the organic phase and the inorganic phase are only connected by flexible alkyl chains, lacking the support of rigid Si-O skeleton, in addition, the nano-enhancement fails, and the overall density of the coating collapses.

[0132] Those skilled in the art will understand that the above discussion of any of the embodiments is merely exemplary and is not intended to suggest that the scope of the present application is limited to these examples; under the concept of the present application, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other changes of different aspects of the present application as described above, which are not provided in detail for the sake of brevity.

[0133] The present application is intended to cover all such alternatives, modifications, and variations as fall within the broad scope of the appended claims. Accordingly, any and all such modifications, variations, and equivalents that fall within the spirit and scope of the present application are intended to be included within the scope of the claims.

Claims

1. A method for preparing a fluorinated coating for ultra-weather-resistant wrapping tape, characterized in that, The preparation steps are as follows: Step S1: Add tetraethyl orthosilicate and 0.1 mol / L hydrochloric acid aqueous solution to propylene glycol methyl ether acetate solvent, heat to 50-70℃, react for 1.5-2.5 h, and rotate at 400-600 rpm to obtain a transparent sol; Step S2: Add the hyperbranched perfluorinated polyether glycol and transparent sol to propylene glycol methyl ether acetate solvent, heat to 70-90℃, stir for 2-4 hours at 300-500 rpm, and the reaction is complete to obtain the prepolymer. Step S3: Add modified nano-silica to the prepolymer, heat to 30-40℃, sonicate for 20-40 min at 400-600W, place in a high-speed homogenizer, react for 50-70 min at 1800-2200 rpm, add leveling agent, stir for 10-20 min, reduce the speed to 150-250 rpm, add hexamethylene diisocyanate trimer and catalyst dibutyltin dilaurate, stir for 10-20 min, increase the speed to 700-900 rpm, and obtain fluorinated coating; In step S1, the mass ratio of tetraethyl orthosilicate to hydrochloric acid aqueous solution is 1:0.07-0.09; The mass ratio of hyperbranched perfluoropolyether diol to transparent sol in step S2 is 1.7-1.8:1; In step S3, the mass ratio of modified nano-silica, prepolymer, leveling agent, hexamethylene diisocyanate trimer, and catalyst is 0.028-0.032:1:0.0028-0.0032:0.21-0.23:0.004-0.

006. The modified nano-silica is perfluorooctyltriethoxysilane modified nano-silica; The preparation steps of the hyperbranched perfluoropolyether diol are as follows: Step A1: Under a nitrogen atmosphere, add perfluoropolyether diol to a tetrahydrofuran solution, stir to dissolve, heat to 50-70℃, add glycidyl methacrylate and triethylamine, react for 5-7 hours until the reaction is complete, cool to 20-30℃, and distill under reduced pressure to obtain epoxy-terminated perfluoropolyether diol. Step A2: Under a nitrogen atmosphere, epoxy-terminated perfluoropolyether glycol is added to tetrahydrofuran solvent and stirred to dissolve. Hydroxyethyl acrylate and initiator azobisisobutyronitrile are added, the temperature is raised to 60-80℃, and the reaction is carried out for 7-9 hours. The reaction is completed, and the reaction solution is obtained. Step A3: Add the reaction solution to deionized water, stir and mix, add the catalyst triethylamine, heat to 90-110℃, reflux for 3-5 hours, after the reaction is complete, cool to 20-30℃, wash the layers, dry, and distill under reduced pressure to obtain hyperbranched perfluoropolyether diol.

2. The method for preparing a fluorinated coating for ultra-weather-resistant wrapping tape according to claim 1, characterized in that, The mass ratio of perfluoropolyether glycol, glycidyl methacrylate and triethylamine in step A1 is 1:0.2-0.24:0.014-0.

016.

3. The method for preparing a fluorinated coating for ultra-weather-resistant wrapping tape according to claim 1, characterized in that, In step A2, the mass ratio of epoxy-terminated perfluoropolyether glycol, hydroxyethyl acrylate, and initiator is 1:0.48-0.52:0.008-0.

012.

4. The method for preparing a fluorinated coating for ultra-weather-resistant wrapping tape according to claim 1, characterized in that, The mass ratio of the reaction solution to the catalyst in step A3 is 1:0.004-0.

006.

5. The method for preparing a fluorinated coating for ultra-weather-resistant wrapping tape according to claim 1, characterized in that, The modified nano-silica is prepared in the following steps: Step B1: Under a nitrogen atmosphere, add perfluorooctyltriethoxysilane to anhydrous ethanol, add deionized water, heat to 20-30℃, stir and hydrolyze for 20-40 min to obtain hydrolysate; Step B2: Add nano-silica to anhydrous ethanol, sonicate for 20-40 min at 400-600 W, add hydrolysate, heat to 50-70℃, stir for 7-9 h at 500-700 rpm, add acetic acid, adjust pH to 5-6, after the reaction is complete, centrifuge, wash, and vacuum dry to obtain modified nano-silica.

6. The method for preparing a fluorinated coating for ultra-weather-resistant wrapping tape according to claim 5, characterized in that, The mass ratio of perfluorooctyltriethoxysilane to deionized water in step B1 is 1:0.15-0.

17.

7. The method for preparing a fluorinated coating for ultra-weather-resistant wrapping tape according to claim 5, characterized in that, The mass ratio of nano-silica, anhydrous ethanol and hydrolysate mentioned in step B2 is 1:15.6-16:8-8.4.

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