Self-cleaning waterborne fluorocarbon topcoat and its preparation method

Abstract

This invention discloses a self-cleaning waterborne fluorocarbon topcoat and its preparation method, belonging to the field of coating processing. The self-cleaning waterborne fluorocarbon topcoat includes component A and component B. Component A includes component A1 and component A2, with a mass ratio of component A1 to component A2 of 2.5-2.8:1. Component A1 includes the following components in parts by weight: 60-65 parts of hydroxyl ether type fluorocarbon resin emulsion, 20-22 parts of pigment, 5-8 parts of hydroxylated nanofiller, and additives. Component A2 is an aliphatic isocyanate curing agent. Component B includes the following components in parts by weight: 30-35 parts of epoxy modified acrylate emulsion, 15-17 parts of hydroxyl acrylic emulsion, 20-23 parts of thermosensitive photocurable polymer modified nanofibers, 1-1.5 parts of dispersant, 1-2 parts of photocuring agent, and 0.5 parts of photoacid-generating agent. The monomer for preparing the thermosensitive photocurable polymer is composed of N-isopropylacrylamide, glycidyl methacrylate, and vinyltrimethoxysilane. The lifespan of the entire coating after the repainting is close to that of the initial coating.

Description

Technical Field

[0001] This invention belongs to the field of coating processing and relates to a self-cleaning waterborne fluorocarbon topcoat and its preparation method. Background Technology

[0002] Fluorocarbon topcoat combines weather resistance, salt resistance, washability, non-adhesion, impact resistance, and abrasion resistance. Its FC bond structure gives the coating ultra-long weather resistance (lifespan up to 20 years) and 80% high gloss at a 60° angle. It has advantages such as self-cleaning surface and strong adhesion to multiple materials, and is suitable for a variety of substrates such as metal, concrete, and plastic.

[0003] However, fluorocarbon topcoats have extremely high requirements for the cleanliness of the substrate surface. Inadequate substrate treatment will lead to poor adhesion of the fluorocarbon topcoat. Therefore, when replacing an old paint layer with a new one, if the primer is still firm and only the topcoat needs to be replaced, the old primer needs to be rigorously sanded and polished in order to ensure that the new topcoat adheres firmly to the old primer. This will cause the old primer to become thinner and its mechanical strength to decrease. After spraying the new topcoat, the service life of the overall coating is much shorter than that of the initial coating. Summary of the Invention

[0004] The purpose of this invention is to provide a self-cleaning waterborne fluorocarbon topcoat and its preparation method, which solves the problem that when the primer is intact and a new topcoat is applied, the primer surface is subjected to strict treatment such as grinding and polishing to meet the requirements of the fluorocarbon topcoat on the substrate surface, resulting in a thinner primer layer, reduced strength and adhesion, and thus the lifespan of the entire coating after the new paint is much shorter than that of the initial coating.

[0005] The technical solution adopted in this invention is as follows:

[0006] Self-cleaning waterborne fluorocarbon topcoat, comprising component A and component B;

[0007] Component A includes component A1 and component A2, with a mass ratio of component A1 to component A2 of 2.5-2.8:1; component A1 includes the following components in parts by weight: 60-65 parts of hydroxyl ether type fluorocarbon resin emulsion, 20-22 parts of pigment, 5-8 parts of hydroxylated nanofiller, and additives; component A2 is an aliphatic isocyanate curing agent;

[0008] Component B, when considered separately, comprises the following components in parts by weight: 30-35 parts epoxy-modified acrylate emulsion, 15-17 parts hydroxyl acrylic emulsion, 20-23 parts thermosensitive photocurable polymer-modified nanofibers, 1-1.5 parts dispersant, 1-2 parts photocuring agent, and 0.5 parts photoacid-generating agent; wherein the monomers for preparing the thermosensitive photocurable polymer are composed of N-isopropylacrylamide, glycidyl methacrylate, and vinyltrimethoxysilane.

[0009] When the primer is intact and only the topcoat needs to be replaced, the primer surface needs to be strictly treated, such as sanding and polishing, after removing the topcoat before it can be used with fluorocarbon topcoat. However, this will affect the performance of the primer, making the primer layer thinner, and the strength and adhesion will be significantly reduced. The lifespan of the entire coating after the new paint is much shorter than that of the initial coating.

[0010] Therefore, this invention designs component B. Components A1 and A2 in component A are the main components of the fluorocarbon topcoat, while component B is an old layer treatment agent that acts between the new topcoat and the old primer. Component B contains thermosensitive photocurable polymer-modified nanofibers, with N-isopropylacrylamide as the thermosensitive core monomer. In this application, the thermosensitive photocurable polymer shrinks above its phase transition temperature, compressing the nanofibers radially inward during this process, resulting in a radially contracted state of the modified nanofibers. After spraying component B at this temperature, the compressed volume of the modified nanofibers facilitates their entry into the gaps in the old primer layer. After component B is sprayed, the coating temperature is lowered. Once the coating temperature drops below the phase transition temperature, the thermosensitive photocurable polymer expands, completely filling the gaps. At this time, ultraviolet light is applied, and under ultraviolet light, the photoacid-producing agent produces acid, which acts on the thermosensitive photocurable polymer, causing the epoxy groups in the thermosensitive photocurable polymer to open the ring, and then repolymerize under the action of the photocuring agent, realizing the photocuring of the thermosensitive photocurable polymer. The photocured thermosensitive photocurable polymer is basically unaffected by temperature, maintaining a fully filling state with the gap, and realizing the filling and reinforcement of the primer layer; the component B of this application forms a local inlay when embedded with the old primer, with high bonding strength; in addition, the basic film-forming layer provided by the epoxy modified acrylate emulsion and hydroxyl acrylic emulsion of this application can not only cure quickly under light (surface dry), but also react chemically with component A2 in component A, which is beneficial to maintaining the integrity of the coating and providing a spray base for component A.

[0011] In summary, this application utilizes component B as a pre-coat primer treatment agent in conjunction with component A. Primarily based on the phase change filling and photocuring anchoring of thermosensitive photocurable polymer-modified nanofibers, it enhances the strength and adhesion of the primer while being compatible with fluorocarbon paint. The service life of the refurbished new coating is essentially equivalent to that of the initial coating. This solves the current problem where, when the primer is intact, strict treatment such as grinding and polishing is required to meet the surface requirements of the fluorocarbon topcoat, resulting in a thinner primer layer, reduced strength and adhesion, and a significantly shorter overall coating life after repainting compared to the initial coating.

[0012] Furthermore, the mass ratio of N-isopropylacrylamide, glycidyl methacrylate, and vinyltrimethoxysilane is 20:7:3;

[0013] The thermosensitive photocurable polymer-modified nanofibers were prepared by the following method:

[0014] S2.1 PAN nanofibers were prepared by electrospinning. Five parts by weight of PAN nanofibers were pre-oxidized and dispersed in 100 parts by weight of deionized water to obtain a PAN nanofiber dispersion.

[0015] S2.2 Add 100 parts by weight of deionized water and 2 parts by weight of sodium dodecyl sulfate to the reaction vessel, stir evenly, and heat to 60°C. While stirring at 60°C, add 10 parts by weight of N-isopropylacrylamide, 3.5 parts by weight of glycidyl methacrylate, and 1.5 parts by weight of vinyltrimethoxysilane in sequence. After the monomers are added, heat to 70°C and add 0.2 parts by weight of ammonium persulfate initiator. After stirring evenly, react at 70°C for 4 hours to obtain a thermosensitive photocurable polymer.

[0016] S2.3 At 40℃, the PAN nanofiber dispersion is slowly added to the thermosensitive photocurable polymer while stirring. After the addition is complete, the mixture is stirred continuously at 200 rpm for 5 hours, then filtered and washed with deionized water to obtain thermosensitive photocurable polymer modified nanofibers. The amount of thermosensitive photocurable polymer modified nanofibers used is dispersed in deionized water to obtain a thermosensitive photocurable polymer modified nanofiber dispersion for later use.

[0017] Furthermore, the photoacid-generating agent is a triarylthionium salt photoacid-generating agent or a diaryliodonium salt photoacid-generating agent.

[0018] Furthermore, the photocuring agent is the photoinitiator UV-184.

[0019] Furthermore, the hydroxyl ether type fluorocarbon resin emulsion is obtained by emulsion polymerization using trifluorochloroethylene, isobutyl vinyl ether, vinyl ethyl ether, and ethylene glycol monoallyl ether as monomers; wherein the mass ratio of trifluorochloroethylene, isobutyl vinyl ether, vinyl ethyl ether, and ethylene glycol monoallyl ether is 10:5:2:3; and the aliphatic isocyanate curing agent is isocyanate curing agent HT-600.

[0020] Further, the hydroxylated nanofiller includes hydroxylated silica; the pigment includes rutile titanium dioxide, carbon black, or chrome yellow; the additives in component A1 include the following components in weight fractions: 0.8 parts 5040 dispersant, 0.3 parts defoamer DF7010, 0.2 parts polyether-modified polysiloxane leveling agent, 2 parts alcohol ester twelve film-forming aid, and 0.8 parts associative polyurethane thickener.

[0021] Furthermore, the epoxy-modified acrylate emulsion was prepared using functional monomer MAA and epoxy resin E-44 in a mass ratio of 2:5 as the main raw materials.

[0022] Furthermore, the hydroxy acrylic emulsion is one of HD-865 waterborne hydroxy acrylic emulsion, KL-6650 hydroxy pure acrylic emulsion, and hydroxy acrylic emulsion SEACRYL11W01.

[0023] Furthermore, the dispersant in component B is LBD-1 dispersant or CNF dispersant.

[0024] The preparation method of self-cleaning waterborne fluorocarbon topcoat includes the following steps:

[0025] S1. Preparation of Component A: Add hydroxyl ether type fluorocarbon resin emulsion to a dispersion vessel, and add dispersant, defoamer, leveling agent, and film-forming aid from the additives while stirring. After stirring evenly, add pigment and hydroxylated nanofiller in sequence while stirring. After the addition is completed, disperse at high speed at 1200 rpm for 20 min. Finally, add thickener, stir evenly, and add deionized water to adjust the viscosity to 80-90 seconds (25℃) of Forecast cup 4, to obtain component A1, which is individually packaged; directly obtain isocyanate curing agent HT-600 as component A2, which is also individually packaged.

[0026] S2. Preparation of Component B: Add epoxy-modified acrylate emulsion and hydroxyl acrylic emulsion to a mixing vessel and mix evenly to obtain a mixed emulsion; under stirring, add dispersant, photocuring agent and photoacid-generating agent to the mixed emulsion in sequence. After the addition is completed, continue stirring at 200 rpm for 20 min. Then slowly add thermosensitive photocurable polymer-modified nanofiber dispersion. After the addition is completed, continue stirring at 400 rpm for 30 min to obtain component B, which is then individually packaged.

[0027] The amount of component B used is 100-120 g / m³. 2 Component A1 and component A2 are prepared and used immediately. After mixing, component A1 and component A2 are allowed to mature for 10-15 minutes to obtain component A. The amount of component A used is 140-160 g / m³. 2 ;

[0028] The method of using the self-cleaning water-based fluorocarbon topcoat is as follows: Prepare the substrate, retain the primer, heat component B to 40℃ and hold for 10 minutes; after holding, spray evenly onto the substrate primer surface at 40℃; after spraying, cool the coating to 25℃ and maintain the temperature for 20-25 minutes using a 365nm wavelength ultraviolet lamp with a light intensity of 80-100mW / cm². 2 Irradiate for 8-10 minutes to form an intermediate treatment layer. Then spray component A onto the intermediate treatment layer. After spraying, bake at 35°C for 10 minutes, then at 45°C for 5 minutes, and finally at 60°C for 15 minutes. Finally, let it cool naturally to form a self-cleaning waterborne fluorocarbon topcoat layer.

[0029] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0030] 1. The self-cleaning waterborne fluorocarbon topcoat of this invention uses component B as a pre-coat treatment agent for component A. It is mainly based on the phase change filling and photocuring anchoring of thermosensitive photocurable polymer modified nanofibers. While being compatible with fluorocarbon paint, it enhances the strength, adhesion and other properties of the primer. The service life of the new coating after renovation is basically the same as that of the initial coating. This solves the problem that when the primer is intact, when replacing it with a new topcoat, in order to meet the requirements of the fluorocarbon topcoat for the substrate surface, strict treatment such as grinding and polishing is required on the primer surface, which leads to the thinning of the primer layer, the reduction of strength and adhesion and other properties, and the overall life of the new coating after repainting is much shorter than that of the initial coating.

[0031] 2. In this invention, epoxy-modified acrylate emulsion and hydroxyl acrylic emulsion serve as the main film-forming substances in component B, providing a good adhesion substrate for the fluorocarbon paint layer;

[0032] 3. Component B of this invention uses light curing as the main curing method, which has a shorter curing time compared with existing primers. Attached Figure Description

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly described below. It should be understood that the following drawings only show some embodiments of the present invention and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort, wherein:

[0034] Figure 1 These are renderings of a self-cleaning water-based fluorocarbon topcoat.

[0035] Figure 2 This is a cross-sectional SEM image of the primer after treatment with component B of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only for explaining the invention and are not intended to limit the invention; that is, the described embodiments are merely some embodiments of the invention, and not all embodiments. The components of the embodiments of the invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0037] Therefore, the following detailed description of the embodiments of the invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the invention without inventive effort are within the scope of protection of the invention.

[0038] It should be noted that relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0039] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0040] Example 1

[0041] The self-cleaning waterborne fluorocarbon topcoat provided in this embodiment of the invention includes component A and component B;

[0042] Component A comprises component A1 and component A2, with a mass ratio of component A1 to component A2 of 2.6:1. Component A1 comprises the following components in parts by weight: 63 parts hydroxyl ether type fluorocarbon resin emulsion, 21 parts pigment, 7 parts hydroxylated nanofiller, 0.8 parts 5040 dispersant, 0.3 parts defoamer DF7010, 0.2 parts polyether modified polysiloxane leveling agent, 2 parts alcohol ester twelve film-forming aid, and 0.8 parts associative polyurethane thickener. Component A2 is an aliphatic isocyanate curing agent.

[0043] The hydroxyl ether type fluorocarbon resin emulsion in component A is obtained by emulsion polymerization using trifluorochloroethylene, isobutyl vinyl ether, vinyl ethyl ether, and ethylene glycol monoallyl ether as monomers; wherein the mass ratio of trifluorochloroethylene, isobutyl vinyl ether, vinyl ethyl ether, and ethylene glycol monoallyl ether is 10:5:2:3; the aliphatic isocyanate curing agent (component A2) is isocyanate curing agent HT-600; the hydroxylated nanofiller includes hydroxylated silica; the pigment is rutile titanium dioxide; wherein 0.8 parts of 5040 dispersant, 0.3 parts of defoamer DF7010, 0.2 parts of polyether-modified polysiloxane leveling agent, 2 parts of alcohol ester twelve film-forming aid, and 0.8 parts of associative polyurethane thickener are used as additives.

[0044] Component B, taken separately, comprises the following components in parts by weight: 33 parts epoxy-modified acrylate emulsion, 16 parts hydroxyl acrylic emulsion, 22 parts thermosensitive photocurable polymer-modified nanofibers, 1.3 parts dispersant, 1.5 parts photocuring agent, and 0.5 parts photoacid-generating agent; the photoacid-generating agent is a triarylthionium salt photoacid-generating agent; the photocuring agent is photoinitiator UV-184; the epoxy-modified acrylate emulsion is prepared from functional monomer MAA and epoxy resin E-44 in a mass ratio of 2:5 as the main raw materials; the hydroxyl acrylic emulsion is HD-865 waterborne hydroxyl acrylic emulsion; the dispersant in component B is dispersant CNF; wherein, the monomers for preparing the thermosensitive photocurable polymer are composed of N-isopropylacrylamide, glycidyl methacrylate, and vinyltrimethoxysilane, and the mass ratio of N-isopropylacrylamide, glycidyl methacrylate, and vinyltrimethoxysilane is 20:7:3.

[0045] The thermosensitive photocurable polymer-modified nanofibers described in component B were prepared by the following method (the formulation of the thermosensitive photocurable polymer-modified nanofibers was calculated independently):

[0046] S2.1 PAN nanofibers were prepared by electrospinning. Five parts by weight of PAN nanofibers were pre-oxidized and dispersed in 100 parts by weight of deionized water to obtain a PAN nanofiber dispersion.

[0047] S2.2 Add 100 parts by weight of deionized water and 2 parts by weight of sodium dodecyl sulfate to the reaction vessel, stir evenly, and heat to 60°C. While stirring at 60°C, add 10 parts by weight of N-isopropylacrylamide, 3.5 parts by weight of glycidyl methacrylate, and 1.5 parts by weight of vinyltrimethoxysilane in sequence. After the monomers are added, heat to 70°C and add 0.2 parts by weight of ammonium persulfate initiator. After stirring evenly, react at 70°C for 4 hours to obtain a thermosensitive photocurable polymer.

[0048] S2.3 At 40℃, the PAN nanofiber dispersion is slowly added to the thermosensitive photocurable polymer while stirring. After the addition is complete, the mixture is stirred continuously at 200 rpm for 5 hours, then filtered and washed with deionized water to obtain thermosensitive photocurable polymer modified nanofibers. The amount of thermosensitive photocurable polymer modified nanofibers used (the amount used in component B) is dispersed in deionized water to obtain a thermosensitive photocurable polymer modified nanofiber dispersion for later use.

[0049] The preparation method of self-cleaning waterborne fluorocarbon topcoat includes the following steps:

[0050] S1. Preparation of Component A: Add hydroxyl ether type fluorocarbon resin emulsion to a dispersion vessel, and add 5040 dispersant, defoamer, leveling agent, and film-forming aid while stirring. After stirring evenly, add pigment and hydroxylated nanofiller in sequence while stirring. After the addition is completed, disperse at high speed at 1200 rpm for 20 min. Finally, add thickener, stir evenly, and add deionized water to adjust the viscosity to 80-90 seconds (25℃) of Forecast cup 4, to obtain component A1, which is individually packaged; directly obtain isocyanate curing agent HT-600 as component A2, which is also individually packaged.

[0051] S2. Preparation of Component B: Epoxy-modified acrylate emulsion and hydroxyl acrylic emulsion are added to a mixing vessel and mixed evenly to obtain a mixed emulsion. Under stirring, dispersant CNF, photocuring agent, and photoacid-generating agent are added to the mixed emulsion in sequence. After the addition is completed, stirring is continued at 200 rpm for 20 min. Then, thermosensitive photocurable polymer-modified nanofiber dispersion is slowly added. After the addition is completed, stirring is continued at 400 rpm for 30 min to obtain component B, which is then individually packaged.

[0052] Construction method: The dosage of component B is 100-120 g / m³. 2 Component A1 and component A2 are prepared and used immediately. After mixing, component A1 and component A2 are allowed to mature for 10-15 minutes to obtain component A. The amount of component A used is 140-160 g / m³. 2 ;

[0053] The method of using the self-cleaning water-based fluorocarbon topcoat is as follows: Prepare the substrate, retain the primer, heat component B to 40℃ and hold for 10 minutes; after holding, spray evenly onto the substrate primer surface at 40℃; after spraying, cool the coating to 25℃ and maintain the temperature for 20-25 minutes using a 365nm wavelength ultraviolet lamp with a light intensity of 80-100mW / cm². 2Irradiate for 8-10 minutes to form an intermediate treatment layer. Then spray component A onto the intermediate treatment layer. After spraying, bake at 35°C for 10 minutes, then at 45°C for 5 minutes, and finally at 60°C for 15 minutes. Finally, let it cool naturally to form a self-cleaning waterborne fluorocarbon topcoat layer.

[0054] This embodiment describes the effect of replacing old paint (with the primer retained) on a steel plate (with epoxy zinc-rich primer) as follows: Figure 1 As shown, the topcoat formed by this application has a smooth and flat surface and good hiding power, which can complete the replacement of the topcoat.

[0055] In this embodiment, after component B treats the primer, the local cross-sectional SEM image of the primer (surface image exposed after sanding) is as follows: Figure 2 As shown, embedded short strip structures (modified nanofibers) can be seen, indicating that the modified nanofibers of component B in this application can be embedded in the primer.

[0056] Example 2-3

[0057] Based on Example 1, Examples 2-3 differ from Example 1 in that the mass ratio of component A1 to component A2 is different, as shown in Table 1. All other aspects are the same.

[0058] Table 1. Mass ratio of component A1 to component A2 in Examples 2-3

[0059]

[0060] Examples 4-5

[0061] Based on Example 1, Examples 4-5 differ from Example 1 in that the proportion of component A1 is different, as shown in Table 2. All other aspects are the same.

[0062] Table 2 shows the formulation of component A1 in Examples 4-5.

[0063]

[0064] Examples 6-7

[0065] Based on Example 1, Examples 6-7 differ from Example 1 in that the proportion of component B is different, as shown in Table 3. All other aspects are the same.

[0066] Table 3 shows the formulation of component B in Examples 6-7.

[0067]

[0068] Comparative Example 1

[0069] Based on Example 1, unlike Example 2, the self-cleaning waterborne fluorocarbon topcoat provided in this comparative example only includes component A and does not include component B; the preparation method is modified accordingly to refer to Example 1.

[0070] The self-cleaning waterborne fluorocarbon topcoat provided in this comparative example comprises component A1 and component A2, with a mass ratio of component A1 to component A2 of 2.6:1. Component A1 comprises the following components in parts by weight: 63 parts hydroxyl ether type fluorocarbon resin emulsion, 21 parts pigment, 7 parts hydroxylated nanofiller, 0.8 parts 5040 dispersant, 0.3 parts defoamer DF7010, 0.2 parts polyether modified polysiloxane leveling agent, 2 parts alcohol ester twelve film-forming aid, and 0.8 parts associative polyurethane thickener. Component A2 is an aliphatic isocyanate curing agent.

[0071] The hydroxyl ether type fluorocarbon resin emulsion in component A is obtained by emulsion polymerization using trifluorochloroethylene, isobutyl vinyl ether, vinyl ethyl ether, and ethylene glycol monoallyl ether as monomers; wherein the mass ratio of trifluorochloroethylene, isobutyl vinyl ether, vinyl ethyl ether, and ethylene glycol monoallyl ether is 10:5:2:3; the aliphatic isocyanate curing agent (component A2) is isocyanate curing agent HT-600; the hydroxylated nanofiller includes; and the pigment is rutile titanium dioxide.

[0072] Comparative Example 2

[0073] Based on Example 1, the difference from Example 1 is that this comparative example component A only includes component A1 and does not include component A2, while the rest are the same.

[0074] Comparative Example 3

[0075] Based on Example 1, the difference from Example 1 is that the filler in component A of this comparative example includes silica and has not undergone hydroxylation modification, while the rest are the same.

[0076] Comparative Example 4

[0077] Based on Example 1, the difference from Example 1 is that component B in this comparative example does not include epoxy-modified acrylate emulsion, but all other components are the same.

[0078] Comparative Example 5

[0079] Based on Example 1, the difference from Example 1 is that component B in this comparative example does not include hydroxy acrylic emulsion, but all other components are the same.

[0080] Comparative Example 6

[0081] Based on Example 1, the difference from Example 1 is that component B in this comparative example does not include thermosensitive photocurable polymer modified nanofibers, but all other components are the same.

[0082] Comparative Example 7

[0083] Based on Example 1, the difference from Example 1 is that the nanofibers in component B of this comparative example are not modified by thermo-sensitive photocurable polymer, but directly use PAN nanofibers, while the rest are the same.

[0084] Comparative Example 8

[0085] Based on Example 1, the difference from Example 1 is that the monomer used in component B of this comparative example to prepare the thermosensitive photocurable polymer does not include N-isopropylacrylamide, while the rest are the same, and the preparation method is adapted according to Example 1.

[0086] Comparative Example 9

[0087] Based on Example 1, the difference from Example 1 is that the monomer used in component B of this comparative example to prepare the thermosensitive photocurable polymer does not include glycidyl methacrylate, but all other components are the same, and the preparation method is adapted according to Example 1.

[0088] Comparative Example 10

[0089] Based on Example 1, the difference from Example 1 is that the monomer used in component B of this comparative example to prepare the thermosensitive photocurable polymer does not include vinyltrimethoxysilane, but all other components are the same, and the preparation method is adapted according to Example 1.

[0090] Comparative Example 11

[0091] Based on Example 1, the difference from Example 1 is that component B in this comparative example does not include a photocuring agent, but all other components are the same.

[0092] Comparative Example 12

[0093] Based on Example 1, the difference from Example 1 is that component B in this comparative example does not include a photoacid-generating agent, but all other aspects are the same.

[0094] Experimental Example 1

[0095] Test substrate 1: Steel plate (Q235, 150mm×70mm×2mm) + shop primer (epoxy zinc-rich shop primer, 25±2μm film thickness) + fluorocarbon topcoat provided in Example 1 (usage amount: 160g / m²) 2 The spraying and curing methods refer to existing technologies and serve as a blank group (initial paint layer).

[0096] Test substrate 2: Part of test substrate 1 was sanded to remove the topcoat, leaving the primer (film thickness 20±2μm, wiped with acetone, oil-free and dust-free).

[0097] Test method: According to the application method of the topcoat shown in Example 1, the topcoats prepared in Examples 1-7 and Comparative Examples 1-12 were used to spray the test substrate 2. The adhesion level of the topcoat to the primer (F1), the adhesion level of the entire paint layer (the overall paint of primer + topcoat) to the substrate (F2), and the service life of the entire paint layer (the overall paint of primer + topcoat) (through accelerated aging test) were tested on the blank group and the test substrate 2. The test results are shown in Table 4.

[0098] The testing methods for adhesion grades (F1) and (F2) are as follows: refer to standard GB / T 9286-2021 "Cross-cut test for paint and varnish films";

[0099] Service life: Equipment: Q-SUN Xenon Lamp Aging Test Chamber, Parameters: Irradiance: 0.51W / m 2 @340nm, blackboard temperature: 65±3℃, chamber temperature: 38±3℃, relative humidity: 50±5%, cycle: 102min light exposure + 18min spraying, test cycle: 2000 hours; reference standard: GB / T 1865 Xenon lamp aging test standard; failure judgment criteria: gloss retention rate <50%, obvious chalking (≥3 level), cracks or peeling, color difference ΔE>5, any one (or several of these) are judged as failure; the longer the aging time that causes paint layer failure, the longer the service life of the paint layer in natural environment.

[0100] Table 4 Test Results of Topcoat Renovation Effect

[0101]

[0102] The coating refurbished using component B in this invention is close to the initial coating and has a long service life (refer to aging test).

[0103] Experimental Example 2

[0104] Using test substrate 2 as the substrate, the mechanical strength of the primer after component B in Example 1 and Comparative Examples 4-12 was fully cured after being sprayed onto the primer was tested; blank group 1 was referenced to test substrate 1, without topcoat (the primer was the original paint), and blank group 2 was referenced to test substrate 2, without component B and topcoat (the primer was directly applied after sanding). The results are shown in Table 5.

[0105] The testing methods are existing technologies, and the corresponding standards referenced include: GB / T 1732-1993 "Determination of Impact Resistance of Paint Films", GB / T 1733-1993 "Determination of Water Resistance of Paint Films" (GB / T 1733-1993), GB / T 6739-2006 "Determination of Hardness of Paint Films by Pencil Method", GB / T 1768-2006 "Determination of Abrasion Resistance of Paints and Varnishes by Rotating Rubber Grinding Wheel Method", and GB / T 9274-1988 "Determination of Resistance to Liquid Media of Paints and Varnishes".

[0106] Acid and alkali resistance: Immerse in 5% H2SO4 solution and 5% NaOH solution for 72 hours respectively, and observe the changes in appearance; (room temperature 25℃)

[0107] Water resistance: Immerse in distilled water for 72 hours (at room temperature 25℃) and observe the changes in appearance;

[0108] Abrasion resistance: Refer to the standard and test the abrasion loss (mg / 500r).

[0109] Table 5 Results of the reinforcing effect of component B on the primer

[0110]

[0111] Experimental Example 3

[0112] According to the method of using the topcoat shown in Example 1, the topcoat prepared in Examples 1-7 was used to spray the test substrate 2 (Experiment 1) with the topcoat, and the basic properties of the topcoat in Examples 1-7 were tested. The results are shown in Table 6.

[0113] Water resistance: Test method for water resistance of paint film (GB / T 1733-1993), immersion in water for 240 hours;

[0114] Gasoline resistance: GB / T 1734-1993 "Test Method for Gasoline Resistance of Coatings", gasoline immersion (Method A) for 24 hours;

[0115] Surface drying time: GB / T 1728-1979(1989) Determination of drying time of paint film and putty film;

[0116] Gloss: GB / T 9754-2007 "Determination of specular gloss of paint films without metallic pigments";

[0117] Chemical resistance: GB / T 9274-1988 "Determination of resistance to liquid media for paints and varnishes", immerse in 5% H2SO4 solution and 5% NaOH solution for 72 hours respectively, and observe the changes in appearance; (room temperature 25℃)

[0118] Table 6. Basic properties of topcoat in Examples 1-7

[0119]

[0120] Based on the above data, it can be seen that component B in this application can significantly improve the performance of the old primer after sanding. After the topcoat is sprayed, the weather resistance (aging test, service life) of the overall refurbished paint layer is significantly improved compared with the refurbished paint layer without component B.

[0121] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A self-cleaning water-based fluorocarbon topcoat characterized by: The component A and the component B are included; The component A includes component A1, component A2, and the mass ratio of component A1 to component A2 is 2.5-2.8:1; the component A1 includes the following components in parts by weight: 60-65 parts of hydroxyl ether type fluorocarbon resin emulsion, 20-22 parts of pigment, 5-8 parts of hydroxylated nano filler, and auxiliary agent; the component A2 is aliphatic isocyanate curing agent; The component B alone includes the following components in parts by weight: 30-35 parts of epoxy modified acrylate emulsion, 15-17 parts of hydroxyl acrylic emulsion, 20-23 parts of temperature-sensitive light-cured polymer modified nanofiber, 1-1.5 parts of dispersing agent, 1-2 parts of light-curing agent, and 0.5 parts of photoacid generator; wherein the monomers for preparing the temperature-sensitive light-cured polymer are composed of N-isopropyl acrylamide, glycidyl methacrylate, and vinyl trimethoxysilane.

2. The self-cleaning water-based fluorocarbon finish according to claim 1, characterized in that: The mass ratio of N-isopropyl acrylamide, glycidyl methacrylate, and vinyl trimethoxysilane is 20:7:3; The temperature-sensitive light-cured polymer modified nanofiber is prepared by the following method: S2.1, PAN nanofiber is prepared by electrospinning method, 5 parts by weight of PAN nanofiber is pre-oxidized and dispersed in 100 parts by weight of deionized water to obtain PAN nanofiber dispersion liquid; S2.2, 100 parts by weight of deionized water and 2 parts by weight of sodium dodecyl sulfate are added into a reaction container, stirred uniformly, heated to 60℃, 10 parts by weight of N-isopropyl acrylamide, 3.5 parts by weight of glycidyl methacrylate, and 1.5 parts by weight of vinyl trimethoxysilane are added in turn under stirring at 60℃, after the monomer feeding is completed, 0.2 parts by weight of ammonium persulfate initiator is added after heating to 70℃, stirred uniformly, and reacted at 70℃ for 4 hours to obtain temperature-sensitive light-cured polymer; S2.3, the PAN nanofiber dispersion liquid is slowly added into the temperature-sensitive light-cured polymer under stirring at 40℃, after the feeding is completed, the stirring is continued at a stirring speed of 200 rpm for 5 hours, then filtered and washed with deionized water to obtain temperature-sensitive light-cured polymer modified nanofiber; the required amount of temperature-sensitive light-cured polymer modified nanofiber is dispersed in deionized water to obtain temperature-sensitive light-cured polymer modified nanofiber dispersion liquid, which is ready for use.

3. The self-cleaning water-based fluorocarbon finish according to claim 1, characterized in that: The photoacid generator is triaryl sulfonium salt photoacid generator or diaryl iodonium salt photoacid generator.

4. The self-cleaning water-based fluorocarbon finish according to claim 1, characterized in that: The light-curing agent is photoinitiator UV-184.

5. The self-cleaning water-based fluorocarbon finish as claimed in claim 1, wherein: The hydroxyl ether type fluorocarbon resin emulsion is obtained by emulsion polymerization with trifluorochloroethylene, isobutyl vinyl ether, vinyl ethyl ether, and ethylene glycol monoallyl ether as monomers; wherein the mass ratio of trifluorochloroethylene, isobutyl vinyl ether, vinyl ethyl ether, and ethylene glycol monoallyl ether is 10:5:2:3; the aliphatic isocyanate curing agent is isocyanate curing agent HT-600.

6. The self-cleaning water-based fluorocarbon finish as claimed in claim 1, wherein: The hydroxylated nano-filler includes hydroxylated silicon dioxide; the pigment includes rutile titanium dioxide or carbon black or chrome yellow; the auxiliary in the component A1 includes the following components in parts by weight: 0.8 parts of 5040 dispersant, 0.3 parts of defoaming agent DF7010, 0.2 parts of polyether modified polysiloxane leveling agent, 2 parts of alcohol ester twelve film forming auxiliary, and 0.8 parts of associated polyurethane thickening agent.

7. The self-cleaning water-based fluorocarbon finish as claimed in claim 1, wherein: The epoxy-modified acrylate emulsion is prepared from functional monomer MAA and epoxy resin E-44 as main raw materials in a mass ratio of 2:

5.

8. The self-cleaning water-based fluorocarbon finish as claimed in claim 1, wherein: The hydroxyl acrylate emulsion is one of HD-865 water-based hydroxyl acrylate emulsion, KL-6650 hydroxyl pure acrylate emulsion and hydroxyl acrylate emulsion SEACRYL11W01.

9. The self-cleaning water-based fluorocarbon finish as claimed in claim 1, wherein: The dispersant in the component B is LBD-1 dispersant or dispersant CNF.

10. The method for preparing the self-cleaning waterborne fluorocarbon topcoat according to claim 1, characterized in that: The method comprises the following steps: S1, preparing component A: adding hydroxyl ether type fluorocarbon resin emulsion in a dispersion kettle, adding dispersant, defoaming agent, leveling agent and film forming auxiliary in the auxiliary under stirring, uniformly stirring, then adding pigment and hydroxylated nano-filler under stirring, high-speed dispersing for 20 minutes at 1200 rpm after adding, finally adding thickening agent, uniformly stirring, then adding deionized water to adjust the viscosity to 80-90 seconds (25 DEG C) in a coating-4 cup, obtaining component A1, independently packaging; directly obtaining isocyanate curing agent HT-600 as component A2, independently packaging; S2, preparing component B: adding epoxy-modified acrylate emulsion and hydroxyl acrylate emulsion in a mixing kettle, mixing uniformly to obtain a mixed emulsion; under stirring, adding dispersant, photocuring agent and photoacid generator into the mixed emulsion in sequence, continuing to stir for 20 minutes at 200 rpm after adding, then slowly adding temperature-sensitive photocuring polymer modified nano-fiber dispersion, continuously stirring for 30 minutes at 400 rpm after adding, obtaining component B, independently packaging; wherein the component B is used in an amount of 100-120 g / m 2 ; the component Al and the component A2 are mixed and aged for 10-15 minutes to obtain component A after mixing, and the component A is used in an amount of 140-160 g / m 2 ; The method for using the self-cleaning water-based fluorocarbon topcoat is: substrate treatment, primer retention, heating component B to 40 DEG C, and keeping warm for 10 min; after the keeping warm is finished, uniformly spraying on the substrate primer surface at 40 DEG C, after the spraying is finished, cooling the coating, maintaining 20-25 min after the temperature drops to 25 DEG C, using a UV lamp with a wavelength of 365 nm, light intensity 80-100 mW / cm 2 , irradiating for 8-10 min, forming an intermediate treatment layer, spraying component A on the intermediate treatment layer, after the spraying is finished, baking at 35 DEG C for 10 min, baking at 45 DEG C for 5 min, finally baking at 60 DEG C for 15 min, and finally naturally cooling, forming a self-cleaning water-based fluorocarbon topcoat layer.

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