Fluorine-containing polyurethane resin, and preparation method and application thereof

Abstract

The application belongs to the technical field of high polymer materials, and particularly relates to a fluorine-containing polyurethane resin and a preparation method and application thereof. The fluorine-containing polyurethane resin prepared by the application is composed of the following components in parts by weight: hydrogenated fluorine-containing polyol 40-45 parts, polythiol 20-70 parts, isocyanate 50-70 parts, and catalyst 0.6-1.2 parts. The hydrogenated fluorine-containing polyol is selected from one or more of hydrogenated hexafluorobisphenol A and hydrogenated hexafluorobisphenol A polyether polyol. The molecular weight of the polythiol is 250-500. The molar ratio of -OH in the hydrogenated fluorine-containing polyol, -SH in the polythiol and -NCO in the isocyanate is 1:(0-3):(0.5-4). Specifically, fluorine-containing polyols and isocyanate substances are used as initial raw materials, and a specific reactive additive is used for polymerization to prepare a solvent-free self-cleaning antifouling fluorine-containing polyurethane coating. The method realizes super strong antifouling self-cleaning of the surface of various materials in extremely harsh environments, reduces waste emissions, and is environmentally friendly.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high polymer materials, and particularly relates to a fluorine-containing polyurethane resin and a preparation method and application thereof. BACKGROUND

[0002] The information disclosed in the background of the present application is only intended to increase the understanding of the overall background of the present application, and should not necessarily be regarded as acknowledging or implicitly suggesting that this information constitutes prior art known to those skilled in the art.

[0003] Traditional polyurethane coatings are difficult to meet the high-end protection requirements due to environmental protection, performance and process defects, and existing improvement schemes have significant shortcomings. For example, traditional polyurethane coating materials have the following technical defects:

[0004] (1) Solvent-based systems contain a large amount of volatile organic compounds (VOCs), which do not meet environmental protection requirements; (2) existing solvent-free systems have high viscosity and poor construction performance; (3) insufficient chemical corrosion resistance, especially in harsh environments such as acid, alkali and salt spray; (4) narrow temperature resistance range (-30℃~120℃); (5) poor weather resistance, prone to yellowing and powdering; (6) mechanical properties significantly decrease at extreme temperatures; (7) high surface energy, insufficient stain resistance.

[0005] Existing improvement technologies have made many contributions, but still have obvious deficiencies: (1) adding solvents to improve processability but leading to environmental pollution; (2) conventional fluorinated modification sacrifices the flexibility and mechanical properties of the material; (3) multi-layer coating system has weak interfacial adhesion, easy to delaminate, and the process is complex and costly.

[0006] Therefore, the technical personnel in the field urgently need to explore a new type of polyurethane resin with environmental protection (solvent-free, low VOCs), high performance (wide temperature range adaptability, chemical corrosion resistance, high weather resistance), strong interfacial adhesion (avoiding delamination failure), and convenient construction (low viscosity, easy to coat) to overcome the above problems. SUMMARY

[0007] In view of the needs of the prior art, the purpose of the present application is to provide a fluorine-containing polyurethane resin and its preparation method and application. The material provided by the present application takes hydrogenated fluorine-containing polyols and isocyanate substances as initial raw materials, is prepared by specific reactive additives, and realizes the preparation of a solvent-free self-cleaning antifouling fluorine-containing polyurethane coating. The coating preparation method solves the environmental protection problem through solvent-free design; realizes low viscosity by optimizing the formula, improves the workability; combines fluorine element modification and hydrogenation treatment, synergistically enhances the adhesion, chemical resistance, weather resistance and mechanical strength; uses polythiol crosslinking and aliphatic isocyanate to avoid aromatic oxidation problems, expand the temperature range adaptability, and strengthen the bonding force of the resin and the substrate through chemical anchoring (-NCO group) and physical adsorption (aliphatic polarity), which has significant advantages and wide application prospect in the fields of protective coating and adhesive.

[0008] Specifically, the present application provides the following technical solutions:

[0009] In a first aspect of the present application, a fluorine-containing polyurethane resin is provided, which is composed of the following components in parts by weight: hydrogenated fluorine-containing polyol 40-45 parts, polythiol 20-70 parts, isocyanate 50-70 parts, and catalyst 0.6-1.2 parts; wherein the hydrogenated fluorine-containing polyol is selected from one or more of hydrogenated fluorine-containing bisphenol A and hydrogenated fluorine-containing bisphenol A polyether polyol; the molecular weight of the polythiol is 250-500; and the molar ratio of -OH in the hydrogenated fluorine-containing polyol, -SH in the polythiol, and -NCO in the isocyanate is 1:(0-3):(0.5-4).

[0010] Preferably, the fluorine-containing polyurethane resin is composed of the following components in parts by weight: hydrogenated fluorine-containing polyol 42-44 parts, polythiol 40-50 parts, isocyanate 60-68 parts, and catalyst 0.8-1.1 parts; and the molar ratio of -OH in the hydrogenated fluorine-containing polyol, -SH in the polythiol, and -NCO in the isocyanate is 1:0.8-2.5:2-3.5.

[0011] Preferably, the fluorine-containing polyurethane resin is composed of the following components in parts by weight: hydrogenated fluorine-containing polyol 43.5 parts, polythiol 43.4 parts, isocyanate 66.2 parts, and catalyst 1 part; and the molar ratio of -OH in the hydrogenated fluorine-containing polyol, -SH in the polythiol, and -NCO in the isocyanate is 1:2:3.15.

[0012] Preferably, the hydrogenated fluorine-containing bisphenol A includes hydrogenated hexafluorobisphenol A, and the hydrogenated fluorine-containing bisphenol A polyether polyol includes hydrogenated hexafluorobisphenol A polyether polyol, with a molecular weight of 600-800.

[0013] Preferably, the isocyanate is selected from one or more of isophorone diisocyanate (IPDI), hexamethylene diisocyanate (HDI), dicyclohexylmethane diisocyanate (HMDI).

[0014] Preferably, the polythiol is selected from one or more of polythiol 504, polythiol 405, trimethylolpropane tris(3-mercaptopropionate) (TMPMP), pentaerythritol tetra(3-mercaptopropionate) (PETMP).

[0015] Preferably, the catalyst is selected from one or more of triethylenediamine, triethylamine, N-N-dimethylethanolamine, trimethylbenzylamine, N-N-dimethylcyclohexylamine, dibutyltin dilaurate (DBTDL), succinic acid.

[0016] Preferably, the fluorine-containing polyurethane resin further comprises a chain extender selected from one or more of 1,4-butanediol, ethylenediamine.

[0017] In a second aspect of the present application, a preparation method of the fluorine-containing polyurethane resin is provided, comprising the following steps:

[0018] S1, mixing and dissolving the fluorine-containing polyol and the catalyst for heating reaction, then passing hydrogen into the obtained suspension, and the product is obtained after treatment, which is the hydrogenated fluorine-containing polyol;

[0019] S2, mixing the hydrogenated fluorine-containing polyol, the polythiol, the isocyanate and the catalyst for continuous heating reaction, and the product is obtained.

[0020] Preferably, in step S1, the mass ratio of the fluorine-containing polyol to the catalyst is 5-30:0.1, the concentration of the catalyst is 0.3%-0.6%, and the catalyst is selected from one or more of platinum / carbon catalyst, dibutyltin dilaurate, triethylamine and triethylenediamine.

[0021] Preferably, in step S1, the heating reaction is carried out at a temperature of 100-150℃, a pressure of 5-15 MPa, and a time of 10-15 h.

[0022] Preferably, the post-treatment comprises filtration, vacuum distillation, recrystallization and drying, wherein the mixed solvent used in the recrystallization is obtained by mixing ethanol and water in a mass ratio of 3-6:1.

[0023] In step S2, the continuous heating reaction is first heated at 75-140℃ for 1-4 h, and then heated at 75-140℃ for 1-4 h after the hydrogenated fluorine-containing polyol is dissolved, and then cooled to 30-40℃, and the product is obtained.

[0024] In a third aspect, the present application provides a fluorine-containing polyurethane adhesive comprising the fluorine-containing polyurethane resin of the first aspect.

[0025] In a fourth aspect, the present application provides a fluorine-containing polyurethane coating comprising the fluorine-containing polyurethane resin of the first aspect.

[0026] In a fifth aspect, the present application provides a method for preparing the fluorine-containing polyurethane coating of the fourth aspect, which comprises coating the fluorine-containing polyurethane resin of the first aspect on a substrate and curing to obtain the fluorine-containing polyurethane coating.

[0027] Preferably, the coating has a thickness of 50-200 μm, the coating is performed by one of the following methods: blade coating, spray coating and brush coating; the substrate is selected from the group consisting of hard substrates and / or soft substrates, the hard substrates include metal materials such as stainless steel, inorganic non-metallic materials such as glass and ceramic, and high molecular materials such as hard plastic, and the soft substrates include leather, synthetic leather sheet, textile fabric, non-woven fabric and soft plastic; and the curing is performed at 80-150 ℃ for 2-7 h.

[0028] In a sixth aspect, the present application provides the fluorine-containing polyurethane resin of the first aspect for use in the field of protective coating and / or adhesive material.

[0029] The above one or more technical solutions of the present application have the following advantages:

[0030] (1) The present application provides a polyurethane resin containing fluorine, oxygen and nitrogen atoms. The polymer has excellent adhesion, water resistance, organic solvent resistance, anti-graffiti property, self-cleaning property and corrosion resistance. The excellent reactivity and reactivity of the fluorine-containing polymer can firmly adhere to various materials, including metals, glass, ceramics and the like, by chemical bonding or physical adsorption with the surface of the substrate. The polymer can be coated on the surface of different substrates by spray coating or blade coating, has excellent performance in harsh environments, and can realize self-cleaning function and is difficult to be attached by dirt. The synergistic effect of fluorine and polar groups in the polymer network further increases the hydrophobicity and excellent chemical resistance of the polyurethane resin, thereby improving the adaptability of the resin in harsh environments.

[0031] (2) The present application adopts solvent-free design, avoids environmental pollution caused by solvent volatilization, reduces the internal porosity and defects of the resin, enhances the compactness and chemical resistance of the coating, and reduces the viscosity of the resin in the solvent-free system, improves the construction performance such as scraping, spraying and brushing; the use of hydrogenated fluorine-containing polyols (such as hydrogenated hexafluorobisphenol A) improves the weather resistance and stability of the coating, and the hydrogenation treatment eliminates the aromatic ring, reduces the surface energy of the coating, enhances the hydrophobicity (the contact angle can be as high as 94.1°), thereby improving the self-cleaning performance and anti-fouling performance; the reaction of polythiol and isocyanate generates thiourethane bond, the bond energy is higher than that of traditional urethane bond, which significantly improves the hydrolysis resistance, solvent resistance and thermal stability of the coating, and the molecular weight of polythiol is controlled between 250-500, which optimizes the crosslinking density and forms a dense network structure, further enhancing the chemical corrosion resistance and mechanical strength of the coating; the preferred HDI, IPDI and other aliphatic isocyanates avoid the yellowing and embrittlement problems of aromatic isocyanates at high temperature, and enhance the weather resistance and stability of the coating.

[0032] (3) Anti-fouling performance: fluorine atoms (C-F bonds) are arranged on the surface of the coating to form a low surface energy (10-15 mN / m) barrier, the contact angle can reach 94.1°, which significantly improves the self-cleaning performance, and the pollutants are difficult to adhere and are easily removed (such as the marker is easily removed in the anti-graffiti test);

[0033] Chemical corrosion resistance: the strong electronegativity and chemical inertness of fluorine atoms form a "shielding layer" to effectively resist acid, alkali and salt spray corrosion; at the same time, the thiourethane bond (-NHCOS-) generated by polythiol has higher bond energy, and its hydrolysis resistance and solvent resistance are better than those of traditional urethane bond;

[0034] Weather resistance: fluorine atoms absorb and scatter ultraviolet rays, reducing photodegradation; hydrogenation treatment eliminates aromatic rings to prevent ultraviolet-sensitive groups from causing oxidation. At the same time, aliphatic isocyanates (such as HDI, IPDI) avoid the yellowing problem of aromatic isocyanates, and the coating maintains color stability for a long time;

[0035] Wide temperature range adaptability: fluorine elements (C-F bond energy 485 kJ / mol) and thiourethane bonds provide high thermal stability. At the same time, hydrogenation treatment prevents high-temperature oxidation, and the solvent-free system reduces porosity, and the mechanical strength retention rate of the coating is >90% in the temperature range of -30℃ to 150℃;

[0036] Mechanical strength: polythiol (molecular weight 250-500) ensures moderate crosslinking density, forms a dense network, and improves the toughness of the coating; at the same time, hydrogenation treatment converts rigid aromatic rings into alicyclic structures, realizes "rigidity and flexibility", and avoids brittle fracture (such as maintaining high elongation at break at -30℃);

[0037] Interface bonding force: the unreacted -NCO groups of excess isocyanate form urea bond / urethane bond with the -NH2 in the substrate (such as leather), enhancing the bonding force; at the same time, the alicyclic structure of hydrogenated fluorine-containing polyol forms hydrogen bond with the polar groups of the substrate, improving the adhesion (high peeling strength).

[0038] (4) The molar ratio of -OH in the hydrogenated fluorine-containing polyol, -SH in the polysulfane and -NCO in the isocyanate in the present application is 1:(0~3):(0.5~4), which ensures that the reaction proceeds fully, a uniform cross-linked network is formed, and the existence of unreacted groups is avoided, thereby improving the overall performance of the coating.

[0039] (5) The present application realizes the comprehensive improvement of the environmental protection, weather resistance, chemical resistance, mechanical strength and construction performance of the coating through hydrogenation of fluorine-containing polyol, cross-linking of polysulfane, solvent-free design and optimization of aliphatic isocyanate, solves the defects of traditional polyurethane resin, and has significant advantages and wide application prospect in the field of protective coating. BRIEF DESCRIPTION OF DRAWINGS

[0040] The drawings accompanying the specification of the present application form a part thereof, serve to provide further understanding of the present application, and together with the description of the exemplary embodiments of the present application and the explanation thereof serve to explain the present application, and do not constitute an improper limitation of the present application.

[0041] Figure 1 It is the Fourier transform infrared spectrogram of hydrogenated hexafluorobisphenol A in the embodiment of the present application, and the wave number is 500~4000cm -1 ;

[0042] Figure 2 It is the Fourier transform infrared spectrogram of hydrogenated hexafluorobisphenol A in the embodiment of the present application, and the wave number is 500~1600cm -1 ;

[0043] Figure 3 It is the anti-graffiti test of different embodiments and comparative examples of the present application, wherein (a) is the picture before wiping of example 1 and examples 6~7, (b) is the picture after wiping of example 1 and examples 6~7, (c) is the picture before wiping of comparative examples 2~7, and (d) is the picture after wiping of comparative examples 2~7;

[0044] Figure 4 It is the corrosion resistance test of 0.1 mol / L hydrochloric acid of different embodiments and comparative examples of the present application, wherein (a) is the corrosion picture of the coating of example 1 and examples 6~7, (b) is the corrosion picture of the coating of comparative examples 2~5, and (c) is the corrosion picture of the coating of comparative examples 6~7;

[0045] Figure 5Figure 1 is a chart of the resistance to 0.1 M NaOH solution for different embodiments and comparative examples of the present application, where (a) is the corrosion picture of the coating of Example 1 and Examples 6-7, (b) is the corrosion picture of the coating of Comparative Examples 2-5, and (c) is the corrosion picture of the coating of Comparative Examples 6-7;

[0046] Figure 6 Figure 2 is a chart of the resistance to 0.1 M NaCl solution for different embodiments and comparative examples of the present application, where (a) is the corrosion picture of the coating of Example 1 and Examples 6-7, (b) is the corrosion picture of the coating of Comparative Examples 2-5, and (c) is the corrosion picture of the coating of Comparative Examples 6-7;

[0047] Figure 7 Figure 3 is a chart of the resistance to 2% wt KMn04solution for different embodiments and comparative examples of the present application, where (a) is the corrosion picture of the coating of Example 1 and Examples 6-7, (b) is the corrosion picture of the coating of Comparative Examples 2-5, and (c) is the corrosion picture of the coating of Comparative Examples 6-7;

[0048] Figure 8 Figure 4 is a chart of the adhesion strength test of lap shear after 24 h at -20 °C for different embodiments and comparative examples of the present application;

[0049] Figure 9 Figure 5 is a chart of the adhesion strength test of lap shear after 2.5 h at 90 °C for different embodiments and comparative examples of the present application;

[0050] Figure 10 Figure 6 is a chart of the macroscopic sample picture of lap shear and the macroscopic fracture surface picture of the sample after pull-off for different embodiments and comparative examples of the present application, where (a) is the macroscopic sample picture of lap shear of Example 1 and Examples 6-7, and (b) is the macroscopic fracture surface picture of the sample after pull-off of Example 1 and Examples 6-7. DETAILED DESCRIPTION

[0051] It should be noted that the following detailed description is merely exemplary and is intended to provide further description of the application. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs.

[0052] In order to enable persons skilled in the art to more clearly understand the technical solutions of the present application, the technical solutions of the present application will be described in detail below in combination with specific embodiments.

[0053] Example 1: This embodiment provides a fluorine-containing polyurethane resin and a preparation method

[0054] In this embodiment, the fluorine-containing polyurethane coating specifically includes the following raw materials by weight: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polythiol 504 43.4 parts by weight, HDI 66.2 parts by weight, dibutyltin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A: mercapto in polythiol 504: isocyanate group in HDI is 1:2:3.15.

[0055] The specific steps are as follows:

[0056] (1) 15 parts by weight of hexafluorobisphenol A was dissolved in 200 mL of anhydrous ethanol, heated to 60°C to completely dissolve, then 0.01 parts by weight of platinum / carbon catalyst (mass fraction of catalyst is 5%) was added into the reaction kettle to react, the reaction temperature was 120°C, the pressure was 10 MPa, the time was 12 h, and the stirring was until the suspension was formed; then the reaction kettle was flushed with hydrogen gas 3 times to ensure no oxygen residue. After the reaction was completed, the catalyst was recovered by hot filtering with a sintered glass funnel, the solvent was removed by distillation under reduced pressure, the crude product was obtained, then recrystallized with a mixed solvent (ethanol: water = 8:2, mass ratio), then the obtained product was vacuum dried at 50°C to obtain a white solid, which was hydrogenated hexafluorobisphenol A (4,4-(perfluoropropane-2,2-diyl)bis(cyclohexan-1-ol)), the yield was 88%, the structure of the product was successfully formed which could be confirmed from the Fourier transform infrared spectrum (as shown in Figures 1-2 650~900 cm -1 interval without sharp medium strong peak represents no aromatic ring, 1500~1600 cm -1 no aromatic ring C=C peak represents hydrogenation.

[0057] (2) Under nitrogen protection, mix 43.5 parts by weight of hydrogenated hexafluorobisphenol A, 43.4 parts by weight of polythiol 504, 66.2 parts by weight of HDI, and 1 part of dibutyltin dilaurate catalyst, heat and stir at 100°C for 2 h, at this time the hydrogenated hexafluorobisphenol A is dissolved in the system, the system changes from opaque to transparent liquid, continue to heat at 100°C for 3 h, then cool to 40°C, discharge to obtain a transparent viscous gel liquid, which is a fluorine-containing polyurethane resin.

[0058] Example 2: This embodiment provides a fluorine-containing polyurethane resin and a preparation method

[0059] In this embodiment, only the amount of raw materials in the fluorine-containing polyurethane coating is changed, and the remaining steps are completely consistent with those of Example 1. Specifically includes the following raw materials by weight: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polythiol 504 43.4 parts by weight, HDI 50.5 parts by weight, dibutyltin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A: mercapto in polythiol 504: isocyanate group in HDI is 1:2:2.4.

[0060] Example 3: The present example provides a fluorine-containing polyurethane resin and a preparation method

[0061] In the present example, only the amount of raw materials in the fluorine-containing polyurethane coating is changed, and the remaining steps are completely consistent with those of Example 1. Specifically, the following weight parts of raw materials are included: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 43.4 parts by weight, HDI 84.1 parts by weight, dibutyltin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A: mercapto in polysulfide 504: isocyanate group in HDI is 1:2:4.

[0062] Example 4: The present example provides a fluorine-containing polyurethane resin and a preparation method

[0063] In the present example, only the amount of raw materials in the fluorine-containing polyurethane coating is changed, and the remaining steps are completely consistent with those of Example 1. Specifically, the following weight parts of raw materials are included: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 21.7 parts by weight, HDI 66.2 parts by weight, dibutyltin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A: mercapto in polysulfide 504: isocyanate group in HDI is 1:1:3.15.

[0064] Example 5: The present example provides a fluorine-containing polyurethane resin and a preparation method

[0065] In the present example, only the amount of raw materials in the fluorine-containing polyurethane coating is changed, and the remaining steps are completely consistent with those of Example 1. Specifically, the following weight parts of raw materials are included: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 65.0 parts by weight, HDI 66.2 parts by weight, dibutyltin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A: mercapto in polysulfide 504: isocyanate group in HDI is 1:3:3.15.

[0066] Example 6: The present example provides a fluorine-containing polyurethane resin and a preparation method

[0067] In the present example, only the type of isocyanate in the fluorine-containing polyurethane coating is changed (HDI is replaced by IPDI), and the remaining steps are completely consistent with those of Example 1. Specifically, the following weight parts of raw materials are included: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 43.4 parts by weight, IPDI 87.4 parts by weight, dibutyltin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A: mercapto in polysulfide 504: isocyanate group in IPDI is 1:2:3.15.

[0068] Example 7: The present example provides a fluorine-containing polyurethane resin and a preparation method

[0069] In this embodiment, only the type of isocyanate in the fluorine-containing polyurethane coating is changed (HDI is replaced by HMDI), and the remaining steps are completely consistent with those of Example 1. Specifically, the following raw materials are included by weight: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 43.4 parts by weight, HMDI 103.2 parts by weight, dibutyltin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A: mercapto in polysulfide 504: isocyanate group in HMDI is 1:2:3.15.

[0070] Examples 8-9: This embodiment provides a fluorine-containing polyurethane resin and a preparation method

[0071] In this embodiment, only the type of catalyst in the fluorine-containing polyurethane coating is changed, and the remaining steps are completely consistent with those of Example 1. Specifically, dibutyltin dilaurate (DBTDL) is replaced by triethylenediamine and triethylamine, respectively.

[0072] Example 10:

[0073] This embodiment is different from Example 1 in that no polysulfide 504 component is added in this embodiment, and the remaining components, contents, and preparation methods are completely consistent with those of Example 1. Specifically, the following raw materials are included by weight: hydrogenated hexafluorobisphenol A 43.5 parts by weight, HMDI 66.2 parts by weight, dibutyltin dilaurate 1 part by weight.

[0074] Comparative Example 1:

[0075] This comparative example is different from Example 1 in that no hydrogenated hexafluorobisphenol A component is added in this comparative example, and the remaining components, contents, and preparation methods are completely consistent with those of Example 1. Specifically, the following raw materials are included by weight: polysulfide 504 43.4 parts by weight, HMDI 66.2 parts by weight, dibutyltin dilaurate 1 part by weight.

[0076] Comparative Example 2:

[0077] This comparative example is different from Example 1 in that the amount of raw material added in the fluorine-containing polyurethane coating is changed, and the remaining steps are completely consistent with those of Example 1. Specifically, the following raw materials are included by weight: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 43.4 parts by weight, HMDI 6.3 parts by weight, dibutyltin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A: mercapto in polysulfide 504: isocyanate group in HMDI is 1:2:0.3.

[0078] Comparative Example 3:

[0079] The comparative example is compared with example 1, the difference is that the amount of raw materials in the fluorine-containing polyurethane coating is changed, and the rest of the steps are completely consistent with example 1. Specifically including the following weight parts of raw materials: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 43.4 parts by weight, HDI 125.7 parts by weight, dibutyl tin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A:mercapto in polysulfide 504:isocyanate group in HDI is 1:2:5.98.

[0080] Comparative example 4:

[0081] The comparative example is compared with example 1, the difference is that the amount of raw materials in the fluorine-containing polyurethane coating is changed, and the rest of the steps are completely consistent with example 1. Specifically including the following weight parts of raw materials: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 10.8 parts by weight, HDI 66.2 parts by weight, dibutyl tin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A:mercapto in polysulfide 504:isocyanate group in HDI is 1:0.5:3.15.

[0082] Comparative example 5:

[0083] The comparative example is compared with example 1, the difference is that the amount of raw materials in the fluorine-containing polyurethane coating is changed, and the rest of the steps are completely consistent with example 1. Specifically including the following weight parts of raw materials: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 86.7 parts by weight, HDI 66.2 parts by weight, dibutyl tin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A:mercapto in polysulfide 504:isocyanate group in HDI is 1:4:3.15.

[0084] Comparative example 6:

[0085] The comparative example is compared with example 1, the difference is that the hydrogenated hexafluorobisphenol A in the comparative example is replaced by hydrogenated bisphenol A, and the rest of the ingredients, content and preparation method are completely consistent with example 1. Specifically including the following weight parts of raw materials: hydrogenated bisphenol A 30.1 parts by weight, polysulfide 504 43.4 parts by weight, HDI 66.2 parts by weight, dibutyl tin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated bisphenol A:mercapto in polysulfide 504:isocyanate group in HDI is 1:2:3.15.

[0086] Comparative example 7:

[0087] The difference between the present comparative example and Example 1 is that the hydrogenated hexafluorobisphenol A is replaced by hexafluorobisphenol A, and the rest of the ingredients, contents and preparation methods are completely consistent with Example 1. Specifically, the following weight parts of raw materials are included: hexafluorobisphenol A 42 parts by weight, polysulfide 504 43.4 parts by weight, HDI 66.2 parts by weight, dibutyl tin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hexafluorobisphenol A: mercapto in polysulfide 504: isocyanate group in HDI is 1:2:3.15.

[0088] Comparative Example 8:

[0089] The difference between the present comparative example and Example 1 is that only the type of isocyanate in the fluorine-containing polyurethane coating is changed (HDI is replaced by TDI), and the rest of the steps are completely consistent with Example 1. Specifically, the following weight parts of raw materials are included: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 43.4 parts by weight, TDI 68.6 parts by weight, dibutyl tin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A: mercapto in polysulfide 504: isocyanate group in TDI is 1:2:3.15.

[0090] Comparative Example 8:

[0091] The difference between the present comparative example and Example 1 is that only the type of isocyanate in the fluorine-containing polyurethane coating is changed (HDI is replaced by MDI), and the rest of the steps are completely consistent with Example 1. Specifically, the following weight parts of raw materials are included: hydrogenated hexafluorobisphenol A 43.5 parts by weight, polysulfide 504 43.4 parts by weight, MDI 98.5 parts by weight, dibutyl tin dilaurate 1 part by weight, wherein the molar ratio of hydroxyl in hydrogenated hexafluorobisphenol A: mercapto in polysulfide 504: isocyanate group in TDI is 1:2:3.15.

[0092] Test Example 1:

[0093] The present test example tests the performance of the coating prepared from the resins prepared in Examples 1-9 and Comparative Examples 1-10.

[0094] Experimental process: Take out the resins prepared in Examples 1-9 and Comparative Examples 1-10, coat each sample on a substrate for curing, the curing temperature is 120°C, the curing time is 5h, then perform contact angle test (the instrument used is contact angle measuring instrument (HARKE-SPCA)), the results are shown in Tables 1-2:

[0095] Table 1

[0096]

[0097] Table 2

[0098]

[0099] From the data analysis of Tables 1-2, it can be seen that the fluorine atoms (C-F bonds) in the hydrogenated fluorine-containing polyol (such as hydrogenated hexafluorobisphenol A) used in the embodiments of the present application have high electronegativity and small atomic radius, and are arranged in a directional manner on the surface of the coating to form a low surface energy (10-15 mN / m) barrier, thereby significantly improving the hydrophobicity (the contact angle can reach 94.1°);

[0100] In the above table, the contact angle of Example 1 is 94.1°, which shows high hydrophobicity; the contact angle of Example 2 is 89.6°, which is lower than that of Example 1, which is due to the fact that -NCO itself has hydrophobicity (lower polarity), and the urethane bond generated after the reaction also has hydrophobicity, and the decrease in the content of isocyanate will also cause the decrease in the hydrophobicity of the material; the content of isocyanate in Example 3 is higher than that in Example 1, which is due to the fact that the CO2 generated by the hydrolysis of excess -NCO may form micro-bubbles inside the material, which reduces the surface roughness after curing, and the micro-phase separation is destroyed, and the enrichment of polar groups on the surface leads to the decrease in hydrophobicity; the contact angle of Example 6 is lower than that of Example 1, which is due to the fact that the cyclic structure of IPDI may hinder the complete reaction of -SH and -NCO of fluorine-containing mercaptan, resulting in the residual unreacted -NCO or -SH groups, and the crosslinking density is uneven, and the hydrophilic region is more easily exposed. The catalysts in Examples 8-9 are replaced with those in Example 1, and the catalysts have little effect, and the selection of appropriate catalysts can make the reaction time shorter and more uniform. Example 10 does not add polythiol component, which cannot effectively enrich the surface compared with Example 1, so the contact angle decreases; the other comparative examples and examples are similar in principle.

[0101] (2) Anti-pollution performance test (anti-graffiti, self-cleaning):

[0102] The specific process is as follows: use a marker pen to write marks, and place at room temperature for 6 hours, and then wipe with dry toilet paper;

[0103] The results show that the marks on the coating prepared in Example 1 can be easily wiped off, the marks on the coating prepared in Example 7 have slight traces after wiping, and the marks on the coating prepared in Example 6 are wiped off one layer, and the anti-graffiti effect of the coating prepared in the embodiments of the present application is the best compared with Examples 6-7 (as shown in Figs. Figure 3 (a) and (b)).

[0104] The fluorine atoms (C-F bonds) in the hydrogenated fluorine-containing polyol (such as hydrogenated hexafluorobisphenol A) are arranged in a directional manner on the surface of the coating to form a super-low surface energy barrier, which significantly reduces the affinity for oily pollutants (such as marker ink); and the high contact angle makes it difficult for liquid pollutants to wet the surface, realizing the "lotus effect" (pollutants easily roll off);

[0105] As Figure 3 In (c) and (d), the hydrogenated bisphenol A in Comparative Example 6 (no fluorine) does not contain fluorine, the surface energy is increased, and the anti-graffiti property is significantly decreased (ink is easy to adhere), and the anti-fouling property is deteriorated; the hexafluorobisphenol A in Comparative Example 7 (not hydrogenated) contains a lipophilic aromatic ring, which weakens the oleophobicity (increases the risk of ink penetration), the surface energy is relatively high, and the pollutants are easy to adsorb; the ratio of -SH in Comparative Examples 4-5 is imbalanced, which leads to abnormal crosslinking density, ink residue or coating damage, and pollutants are easy to penetrate; changing the amount of raw materials in the fluorine-containing polyurethane coating in Comparative Examples 2-3, the performance is decreased due to insufficient crosslinking or residual unreacted groups, which leads to easy adsorption of pollutants; Comparative Examples 8-9 are damaged and peeled off during wiping, and the surface is damaged due to oxidative degradation of the aromatic structure.

[0106] (3) Chemical corrosion resistance test:

[0107] The specific test process is as follows: the prepared sample is coated on the steel strip, heated on the heating table at a temperature of 120°C, cooled to 100°C for about 4 h, and the sample coating is completely cured for 2.5 h, and then placed at room temperature for 2 h.

[0108] 2.5 mL of 0.1 mol / L hydrochloric acid, 0.1 mol / L NaOH solution, 0.1 mol / L NaCl solution, and 2% wt potassium permanganate solution were dropped on the sample coating of the steel strip, and the before and after observation was carried out for 8 h.

[0109] Specific phenomena:

[0110] 0.1 mol / L hydrochloric acid: as shown in (a) of Figure 4 , the coating of Example 1 (HDI) has no corrosion marks, and the coatings of Examples 6 (IPDI) and 7 (HMDI) have slight corrosion marks; as shown in (b) of Figure 4 , the coatings of Comparative Examples 2-5 are all severely corroded; as shown in (c) of Figure 4 , the coating of Comparative Example 6 (hydrogenated bisphenol A) has corrosion marks, and the coating of Comparative Example 7 (hexafluorobisphenol A) has slight corrosion marks;

[0111] 0.1 mol / L NaOH solution: as shown in (a) of Figure 5 , the coating of Example 1 (HDI) has no corrosion marks, the coating of Example 7 (HMDI) has slight corrosion marks, and the corrosion of the coating of Example 6 (IPDI) is deeper than that of Example 7; as shown in (b) of Figure 5 , the coatings of Comparative Examples 2-5 are all severely corroded; as shown in (c) of Figure 5As shown in (c), the coating of Comparative Example 7 (hexafluorobisphenol A) had corrosion traces, and the coating of Comparative Example 6 (hydrogenated bisphenol A) had slight corrosion traces.

[0112] 0.1 mol / L NaCI solution: As shown in (a), the coating of Example 1 (HDI) had no corrosion traces, the coating of Example 7 (HMDI) had slight corrosion traces, and the coating of Example 6 (IPDI) was more severely corroded than Example 7; as shown in (b), the coatings of Comparative Examples 2-5 were all severely corroded; as shown in (c), the coating of Comparative Example 7 (hexafluorobisphenol A) had corrosion traces, and the coating of Comparative Example 6 (hydrogenated bisphenol A) had slight corrosion traces. Figure 6 As shown in (a), the coating of Example 1 (HDI) had no corrosion traces, the coating of Example 7 (HMDI) had slight corrosion traces, and the coating of Example 6 (IPDI) was more severely corroded than Example 7; as shown in (b), the coatings of Comparative Examples 2-5 were all severely corroded; as shown in (c), the coating of Comparative Example 7 (hexafluorobisphenol A) had corrosion traces, and the coating of Comparative Example 6 (hydrogenated bisphenol A) had slight corrosion traces. Figure 6 As shown in (b), the coatings of Comparative Examples 2-5 were all severely corroded; as shown in (c), the coating of Comparative Example 7 (hexafluorobisphenol A) had corrosion traces, and the coating of Comparative Example 6 (hydrogenated bisphenol A) had slight corrosion traces. Figure 6 As shown in (b), the coatings of Comparative Examples 2-5 were all severely corroded; as shown in (c), the coating of Comparative Example 7 (hexafluorobisphenol A) had corrosion traces, and the coating of Comparative Example 6 (hydrogenated bisphenol A) had slight corrosion traces.

[0113] 2% wt potassium permanganate solution: As shown in (a), the coating of Example 1 (HDI) had no corrosion traces, the coating of Example 7 (HMDI) had slight corrosion traces, and the coating of Example 6 (IPDI) was more severely corroded than Example 7; as shown in (b), the coatings of Comparative Examples 2-5 were all severely corroded; as shown in (c), the coating of Comparative Example 7 (hexafluorobisphenol A) had corrosion traces, and the coating of Comparative Example 6 (hydrogenated bisphenol A) had slight corrosion traces. Figure 7 As shown in (a), the coating of Example 1 (HDI) had no corrosion traces, the coating of Example 7 (HMDI) had slight corrosion traces, and the coating of Example 6 (IPDI) was more severely corroded than Example 7; as shown in (b), the coatings of Comparative Examples 2-5 were all severely corroded; as shown in (c), the coating of Comparative Example 7 (hexafluorobisphenol A) had corrosion traces, and the coating of Comparative Example 6 (hydrogenated bisphenol A) had slight corrosion traces. Figure 7 As shown in (b), the coatings of Comparative Examples 2-5 were all severely corroded; as shown in (c), the coating of Comparative Example 7 (hexafluorobisphenol A) had corrosion traces, and the coating of Comparative Example 6 (hydrogenated bisphenol A) had slight corrosion traces. Figure 7 As shown in (c), the coating of Comparative Example 7 (hexafluorobisphenol A) had corrosion traces, and the coating of Comparative Example 6 (hydrogenated bisphenol A) had slight corrosion traces.

[0114] Analysis: Hydrogenated fluorine-containing polyols provide high content of fluorine atoms (C-F bonds), which significantly enhance the hydrophobicity of the coating due to their strong electronegativity and low surface energy (about 10-15 mN / m), reducing the penetration of moisture and chemicals, thereby enhancing chemical corrosion resistance; at the same time, due to the high bond energy of C-F bonds (about 485 kJ / mol), the chemical inertness is strong, so it can resist acid, alkali, oxidizing agent, etc. and reduce the penetration of chemicals. In addition, fluorine atoms form a "shielding layer" in the polymer network, reducing the surface energy of the coating and inhibiting the adsorption of pollutants and corrosive media (fluorine forms hydrogen bonds with polar groups such as polyols and isocyanate, enhancing the density of the coating). As shown in (a), the coating of Example 1 (HDI) had no corrosion traces, the coating of Example 7 (HMDI) had slight corrosion traces, and the coating of Example 6 (IPDI) was more severely corroded than Example 7; as shown in (b), the coatings of Comparative Examples 2-5 were all severely corroded; as shown in (c), the coating of Comparative Example 7 (hexafluorobisphenol A) had corrosion traces, and the coating of Comparative Example 6 (hydrogenated bisphenol A) had slight corrosion traces.

[0115] The performance of unhydrogenated hexafluorobisphenol A is reduced due to the easy oxidation and degradation of the aromatic ring; and hydrogenation treatment (see infrared spectrum of Example 1) eliminates the aromatic ring, reduces the chemical attack points, and thus improves the stability.

[0116] The polythiol component contains thiol groups (-SH) which react with isocyanate to form thio urethane bonds (-NHCOS-), which are more resistant to hydrolysis and solvent attack (higher bond energy, stronger chemical stability) than traditional urethane bonds (-NHCOO-). At the same time, polythiol components with molecular weights of 250-500 can optimize crosslinking density, form a dense network, and reduce the diffusion path of chemicals. For example, the performance of Comparative Examples 4-5 (-SH ratio imbalance) deteriorates, indicating that the content control of polythiol is indispensable for chemical resistance, and the anti-graffiti test (Example 1) shows that the coating surface is smooth and contaminants are easy to remove, indirectly proving that the crosslinked network is dense.

[0117] Isocyanate provides -NCO groups which react with -OH and -SH to form a polyurethane network. At the same time, aliphatic isocyanates (such as HDI, IPDI, HMDI) have better chemical resistance and yellowing resistance than aromatic isocyanates (such as TDI) because they do not have easily oxidizable aromatic rings. For example, the performance of Comparative Examples 2-3 (excessively low or high -NCO ratio) deteriorates due to insufficient crosslinking or residual unreacted groups; Examples 6-7 test different isocyanates, and aliphatic long-chain types (such as HDI, HMDI) perform better.

[0118] Solvent-free design avoids VOCs residue, reduces coating porosity and defects (such as pinholes), and prevents chemical medium penetration (background art indicates that solvent-based systems are prone to contamination and failure); at the same time, the hydrogenation step eliminates aromatic rings, improving stability; post-processing (recrystallization, drying) ensures high purity, reduces impurity-induced chemical degradation, and continuous heating promotes uniform crosslinking, forming a defect-free coating.

[0119] Therefore, the high inertness of fluorine elements + stable bonding of polythiol + resistance to oxidation of aliphatic isocyanate + solvent-free dense structure synergistically achieve: 1) Hydrophobicity improvement (high contact angle): reducing water / chemical medium adsorption; 2) Enhanced chemical barrier: resisting H⁺, OH⁻, Cl⁻ ion erosion; 3) Suitable for acid, alkali, salt spray environment, excellent chemical corrosion resistance.

[0120] (4) Weather resistance test:

[0121] 1) Anti-UV aging: The strong electronegativity of fluorine atoms forms a high bond energy (485 kJ / mol) barrier, effectively absorbing and scattering UV light, reducing the photodegradation of polymer chains; fluorine atoms are oriented on the surface of the coating, forming a dense hydrophobic layer, reducing water and oxygen permeation, thereby inhibiting photooxidation. For example, Comparative Example 7 (unhydrogenated hexafluorobisphenol A) has significantly weaker weather resistance than Example 1 (hydrogenated fluorinated compound) due to the presence of aromatic rings (which are prone to UV absorption and degradation). In addition, the hydrogenation reaction (catalytic hydrogenation at 100-150°C) saturates the aromatic ring in hexafluorobisphenol A to an alicyclic structure, eliminating UV-sensitive groups and fundamentally improving the anti-aging ability. For example, Comparative Example 6 (hydrogenated bisphenol A without fluorine) and Comparative Example 7 (unhydrogenated hexafluorobisphenol A) have poor weather resistance, verifying the necessity of the synergy of fluorine + hydrogenation.

[0122] 2) Anti-yellowing: The benzene ring structure of aromatic isocyanate (such as TDI / MDI) is prone to generate quinone structure under UV irradiation, leading to yellowing, so the aliphatic type in Examples 1, 5-6 performs better.

[0123] 3) Anti-powdering: The polythiol (-SH) with a molecular weight of 250-500 forms a thio urethane bond (-NHCOS-) with isocyanate, which is more resistant to hydrolysis and thermal decomposition than traditional urethane bonds (higher bond energy), and the strict molar ratio (-OH:-SH:-NCO=1:2:3.15) in Example 1 ensures complete reaction, forming a dense network, reducing the diffusion path of water / oxygen, and delaying wet heat aging. For example, Comparative Examples 4-5 (-SH ratio is out of balance) and Comparative Examples 2-3 (-NCO ratio is abnormal) have insufficient crosslinking, and the coating is prone to powdering.

[0124] (5) Temperature change resistance performance test:

[0125] The specific test process is as follows: the prepared sample is coated on a steel strip with a contact area of 125 mm 2 , heated on a heating table at a temperature of 120°C, cooled to 100°C in about 4 h, and the sample coating is cured in about 2.5 h, and then placed at room temperature for 2 h.

[0126] The bonded sample steel strip is taken out, three parallel samples are placed in a muffle furnace at 90°C for high temperature testing for 2.5 h, and another three parallel samples are placed at low temperature -20°C for low temperature testing for 24 h, then placed at room temperature for 6 h, and then tested for tensile strength using a KZ-SSBC-500 electronic universal material testing machine. The adhesion strength is obtained by dividing the force generated during the test by the contact area.

[0127] First, the introduction of fluorine improves thermal stability. The high bond energy of C-F bonds resists thermal degradation, and the low surface energy can reduce stress from temperature changes. Hydrogenation eliminates aromatic rings, preventing high-temperature oxidation, which is important for temperature resistance because aromatic rings are prone to oxidation embrittlement at high temperatures.

[0128] Thio urethane bonds formed by polythiols are more resistant to heat than traditional urethane bonds because the bond energy of sulfur bonds is higher. Polythiol with molecular weight 250-500 optimizes crosslinking density, and a high crosslinking network can inhibit molecular chain movement when the temperature changes, reducing deformation and stress accumulation (inhibiting molecular chain slip and volume expansion when the temperature changes). The molar ratio of 1:2:3.15 in the coating prepared in Example 1 ensures sufficient crosslinking and avoids unreacted groups that can initiate degradation during thermal cycling.

[0129] Aliphatic types of isocyanate such as HDI or HMDI do not have aromatic rings, which can avoid high-temperature yellowing and embrittlement, while the use of aromatic isocyanate (such as TDI) can perform poorly when the temperature fluctuates.

[0130] In addition, a solvent-free system avoids the pores left by solvent evaporation, which can become the starting point of cracks when the temperature changes.

[0131] The data of the comparative examples support these points. For example, Comparative Example 6 (without fluorine) and Comparative Example 7 (not hydrogenated) have decreased temperature resistance because of the lack of fluorine protection and the presence of easily oxidized aromatic rings. The imbalance of the ratio in Comparative Examples 2-3 leads to insufficient or excessive crosslinking, affecting thermal stability. For example, too few -NCO (Comparative Example 2) can result in insufficient crosslinking, while too many (Comparative Example 3) can leave unreacted groups that are prone to hydrolysis or oxidation during thermal cycling.

[0132] Table 3-4 and Figure 8 The adhesion strength of the examples and comparative examples at -20°C;

[0133] Table 3

[0134]

[0135] Table 4

[0136]

[0137] Table 5-6 and Figure 9 The adhesion strength of the examples and comparative examples at 90°C;

[0138] Table 5

[0139]

[0140] Table 6

[0141]

[0142] Adhesion strength directly reflects the ability of material to combine with substrate (or other materials) under temperature change, which may cause thermal expansion coefficient difference, internal stress accumulation or chemical bond rupture, all of which are exposed through adhesion strength change. Adhesion strength is an intuitive indicator for evaluating temperature change resistance, and its data change can quantify the temperature change resistance of material.

[0143] From the data in the table, it can be seen that hydrogenated hexafluorobisphenol A provides hydrophobicity and low surface energy, enhancing interface compatibility; its absence leads to a decrease in adhesion between the coating and the substrate. A low ratio of -NCO leads to incomplete reaction with -OH / -SH, a sparse crosslinking network, a decrease in cohesive strength, and a decrease in adhesion strength. Excessive -NCO, although with high crosslinking density, may react with environmental water to form urea bonds (increasing brittleness) or cause excessive rigidity of molecular chains, resulting in a decrease in adhesion strength. If the amount of -SH is insufficient, a decrease in the ratio leads to a decrease in crosslinking rate, incomplete curing, a decrease in flexible chain segments, and an increase in brittleness of the material. Excessive -SH may cause side reactions or lead to excessive local crosslinking, resulting in a decrease in adhesion strength. IPDI and HMDI are more rigid and have greater steric hindrance, and the cyclic structure of such compounds reduces reactivity and crosslinking efficiency, resulting in weak adhesion strength. TDI / MDI contains an aromatic ring structure, which is highly rigid and has poor flexibility of molecular chains, and stress cannot be released during thermal cycling. The aromatic ring is easily aged by ultraviolet light, and the long-term adhesion strength decays quickly. Hydrogenated bisphenol A has reduced hydrophobicity and chemical stability due to the absence of fluorine atoms, and the interface is easily eroded by heat and humidity. The aromatic ring of hexafluorobisphenol A is highly rigid, and the compatibility with polythiol / HDI is poor. The aromatic ring is easily oxidized and degraded, and the temperature change resistance is poor, so the adhesion strength is lower than that of Example 1.

[0144] (6) Mechanical strength test:

[0145] The introduction of fluorine elements is generally considered to reduce the toughness of the material, but the present application balances this through hydrogenation treatment (elimination of aromatic rings) and polythiol crosslinking. Specifically, polythiol (molecular weight 250-500) forms a thiourethane bond (-NHCOS-) through -SH and isocyanate, and the bond energy (≈310 kJ / mol) is higher than that of traditional urethane bonds (-NHCOO-, ≈280 kJ / mol), greatly improving the stability of the network. For example, Comparative Examples 4-5 (improper ratio of -SH): -SH is too low (0.5), resulting in insufficient crosslinking and weak strength; -SH is too high (4), resulting in excessive crosslinking and increased brittleness.

[0146] Hydrogenation treatment (catalytic hydrogenation at 100-150°C) converts the rigid aromatic ring in hexafluorobisphenol A into an alicyclic structure (FTIR verification 1500-1600 cm -1C=C peak), and the high bond energy of C-F bond (485 kJ / mol) provides rigid skeleton, which cooperates with the alicyclic structure to achieve rigid and flexible combination (high temperature anti-creep, low temperature anti-brittle). For example, Comparative Example 6 (hydrogenated bisphenol A without fluorine): insufficient rigidity, high temperature strength decreases; Comparative Example 7 (unhydrogenated containing aromatic ring): aromatic ring high temperature oxidation embrittlement, elongation at break decreases.

[0147] HDI, HMDI and other aliphatic isocyanates have no aromatic structure, which can avoid the embrittlement caused by high temperature oxidation of aromatic (such as TDI). For example, in the examples, the long chain of hexamethylene of HDI gives the molecular chain the freedom of movement, which improves the low temperature toughness, and the strength retention rate is >90% in the temperature range of -30°C~150°C; while the coating containing TDI in the comparative example has a sudden drop of tensile strength by 20% at high temperature (>120°C), and is brittle at low temperature.

[0148] (7) Peeling strength test:

[0149] Specific test process: the prepared sample was coated on the surface of two PVC strips with a length of 12 cm and a width of 2.5 cm to bond, and was hot-pressed on a heating table at a temperature of 120°C. After 4 h, it was reduced to 100°C for 2.5 h, and then was placed at room temperature for 2 h. All the sample strips were tested for peeling tensile test on a KZ-8SBC-500 electronic universal material testing machine, and the test data are shown in Tables 7~8.

[0150] Hydrogenated hexafluorobisphenol A contains hydroxyl (-OH) and alicyclic structure, which can form hydrogen bond or van der Waals force with the polar groups (such as carboxyl, amino) on the surface of the substrate (such as synthetic leather, metal) to improve physical adsorption; at the same time, the fluorine atom reduces the surface energy of the coating, but the alicyclic structure after hydrogenation retains moderate polarity, balancing the hydrophobicity and the wettability of the substrate, avoiding the "difficult adhesion" problem of pure fluorine material; in Comparative Example 6 (hydrogenated bisphenol A without fluorine), the peeling strength decreases (the lack of fluorine leads to the weakening of the hydrophobic layer to the wettability of the substrate); in Comparative Example 7 (unhydrogenated hexafluorobisphenol A), the aromatic ring is too rigid, the interface stress is concentrated, and the bonding force is weak.

[0151] The unreacted -NCO in excess isocyanate can form chemical bond (urea bond / amino acid ester bond) with active groups (-NH2, -OH) of the substrate (such as leather) during curing to achieve chemical anchoring; at the same time, long chain aliphatic isocyanate such as HDI and HMDI has flexible chain to relieve thermal stress, which can inhibit interface peeling. In Comparative Example 2 (-NCO ratio is insufficient, molar ratio 1:2:0.3), the lack of -NCO leads to insufficient chemical bonding, and the interface bonding is weak; TDI aromatic isocyanate is prone to interface peeling due to the mismatch of the thermal expansion coefficient of the rigid aromatic ring and the substrate.

[0152] Polythiol forms a highly cross-linked network, enhancing the bulk strength of the coating and preventing cohesive failure under interfacial stress (peel strength depends on the minimum of the coating's cohesive force and interfacial force); simultaneously, the thiocarbamate bonds (-NHCOS-) are resistant to hydrolysis, maintaining interfacial integrity under humid and hot conditions. Comparative Example 4 (-SH ratio too low, molar ratio 1:0.5:3.15): the cross-linked network is loose, and the peel strength decreases.

[0153] Table 7

[0154]

[0155] Table 8

[0156]

[0157] (8) Bond strength test (including lap shear strength):

[0158] Specific testing procedure: The prepared sample was coated onto a steel strip and bonded together, with a contact area of ​​125 mm². 2 The overlapped steel strips were hot-pressed on a heating table at 120℃ for 4 hours, then cooled to 100℃ for 2.5 hours, and finally left to stand at room temperature for 2 hours. Tensile strength was tested using an XWN-20 microcomputer-controlled electronic universal testing machine. The room temperature adhesion strength was obtained by dividing the force generated during the test by the contact area. Test data are shown in Tables 9-10 and... Figure 10 As shown.

[0159] like Figure 10 As shown, a macroscopic view of the broken sample ( Figure 10 As shown in (a), the sample of Example 6 was in a pulverized state and its viscosity was weaker than that of Example 1; the sample of Example 7 had pores in the reaction, while the sample of Example 1 of the present invention had a more complete reaction contact surface.

[0160] The hydroxyl groups (-OH) and alicyclic structures in hydrogenated hexafluorobisphenol A can form hydrogen bonds or van der Waals forces with polar groups (such as amino and carboxyl groups) on the surface of substrates (such as synthetic leather and leather), enhancing physical adsorption. For example, in Comparative Example 6 (hydrogenated bisphenol A without fluorine): the adhesion is significantly reduced (the lack of fluorine atoms optimizes the surface energy); in Comparative Example 7 (non-hydrogenated hexafluorobisphenol A): the rigidity of the residual aromatic ring leads to interfacial stress concentration and weakened bonding force.

[0161] Unreacted -NCO groups in excess isocyanate form covalent bonds (urea / carbamate bonds) with active groups in the substrate (such as -NH2 in leather) during curing, achieving chemical anchoring. For example, when the -NCO ratio in Comparative Example 2 is insufficient (molar ratio 1:2:0.3), the chemical bonding is inadequate, and the adhesion strength decreases.

[0162] The polythiol forms a dense three-dimensional network, which enhances the cohesive strength of the coating. The thio carbamate bond (-NHCOS-) resists hydrolysis in a humid and hot environment, maintaining the stability of the interface. For example, Comparative Example 4 (too low -SH ratio): insufficient crosslinking results in a loose coating, with decreased adhesion.

[0163] Table 9

[0164]

[0165] Table 10

[0166]

[0167] The preferred embodiments of the present application have been described above with the purpose of enabling not only the best modes contemplated by the inventors of carrying out the application, but also as examples of embodiments of the present application. It is to be understood that various modifications and changes can be made to the present application without departing from the spirit and scope of the present application. Any modifications, equivalent substitutions, improvements, and the like not described above are intended to be included within the scope of the present application.

Claims

1. A fluorine-containing polyurethane resin, characterized by, The fluorine-containing polyurethane resin is prepared from the following components by weight parts: hydrogenated fluorine-containing polyol 40-45 parts, polythiol 20-70 parts, isocyanate 50-70 parts, and catalyst I 0.6-1.2 parts; wherein the hydrogenated fluorine-containing polyol is selected from one or more of hydrogenated hexafluorobisphenol A and hydrogenated hexafluorobisphenol A polyether polyol; the polythiol has a molecular weight of 250-500; the molar ratio of -OH in the hydrogenated fluorine-containing polyol, -SH in the polythiol, and -NCO in the isocyanate is 1:0.8-2.5:2-3.5; The isocyanate is selected from one or more of isophorone diisocyanate, hexamethylene diisocyanate, and dicyclohexylmethane diisocyanate; The polythiol is selected from one or more of polythiol 504, polythiol 405, trimethylolpropane tris(3-mercaptopropionate), and pentaerythritol tetra(3-mercaptopropionate).

2. The fluorine-containing urethane resin according to claim 1, wherein, The fluorine-containing polyurethane resin is prepared from the following components by weight parts: hydrogenated fluorine-containing polyol 42-44 parts, polythiol 40-50 parts, isocyanate 60-68 parts, and catalyst I 0.8-1.1 parts.

3. The fluorine-containing urethane resin according to claim 1, wherein The fluorine-containing polyurethane resin is prepared from the following components by weight parts: hydrogenated fluorine-containing polyol 43.5 parts, polythiol 43.4 parts, isocyanate 66.2 parts, and catalyst I 1 part; and the molar ratio of -OH in the hydrogenated fluorine-containing polyol, -SH in the polythiol, and -NCO in the isocyanate is 1:2:3.

15.

4. The fluorine-containing urethane resin according to claim 1, wherein The catalyst I is selected from one or more of triethylenediamine, triethylamine, N-N-dimethylethanolamine, trimethylbenzylamine, N-N-dimethylcyclohexylamine, and dibutyltin dilaurate.

5. A process for the production of the fluorine-containing polyurethane resin as claimed in any one of claims 1 to 4, characterized by, The method comprises the following steps: S1, mixing and dissolving the fluorine-containing polyol and the catalyst II for heating reaction, then introducing hydrogen into the obtained suspension, and the product is obtained after treatment, i.e. hydrogenated fluorine-containing polyol; S2, mixing the hydrogenated fluorine-containing polyol, polythiol, isocyanate, and catalyst I for continuous heating reaction, and the product is obtained.

6. The production method according to claim 5, wherein In step S1, the mass ratio of the fluorine-containing polyol to the catalyst II is 5-30:0.1, the concentration of the catalyst II is 0.3-0.6%, and the catalyst II is platinum / carbon catalyst; The heating reaction is carried out at a temperature of 100-150°C, a pressure of 5-15 MPa, and for a time of 10-15 h; The post-treatment comprises filtration, reduced pressure distillation, recrystallization, and drying, wherein the mixed solvent used in the recrystallization is obtained by mixing ethanol and water in a mass ratio of 3-6:1; In step S2, the continuous heating reaction is first carried out at 75-140°C for 1-4 h, then the hydrogenated fluorine-containing polyol is dissolved, and the reaction is carried out at 75-140°C for 1-4 h, and then the temperature is lowered to 30-40°C, and the product is obtained.

7. A fluoro-polyurethane adhesive, characterized by, The fluorine-containing polyurethane resin as claimed in any one of claims 1-4.

8. A fluorine-containing polyurethane coating, characterized by, The fluorine-containing polyurethane resin as claimed in any one of claims 1-4.

9. A process for the production of a fluorine-containing polyurethane coating according to claim 8, characterized in that, The fluorine-containing polyurethane resin is coated on a substrate, and is cured to obtain a product. The coating has a thickness of 50 to 200 μm and is applied by one of the methods selected from the group consisting of doctor blade coating, spray coating, and brush coating. The substrate is selected from the group consisting of hard and / or soft substrates. The curing is carried out by vacuum curing at 80 to 150 °C for 2 to 7 h.

10. Use of the fluorine-containing polyurethane resin according to any one of claims 1 to 4 in the field of protective coatings and / or adhesives.

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