The application discloses a divisional application of application number 202111529514.2, application day 2021, 12 months and 14 days, and the application name of an outer transparent self-repairing coating for a photovoltaic transparent backboard and a preparation method thereof.
Detailed Description
For the purpose of making the objects, technical solutions and advantages of the embodiments of the present invention more apparent, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings, and it is apparent that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Because the double-glass assembly is formed by taking glass as the outermost layer of the assembly, when the glass is damaged, the repairing cannot be performed, so that the cost is high, and the recycling property is poor. The invention provides an outer transparent coating for a transparent backboard, which can realize the self-repairing function of the outer transparent coating of the transparent backboard so as to improve the service life and the light utilization rate of a double-sided battery assembly.
The invention provides a self-repairing coating for a photovoltaic backboard, which comprises, by mass, 45-150 parts of an elastomer polymer, 10-50 parts of a fluororesin, 0.3-0.5 part of a leveling agent, 2-8 parts of powder, 0.02-0.10 part of a dispersing agent, 0.18-0.70 part of an antioxidant, 4-10 parts of a UV auxiliary agent, 25-50 parts of a polyisocyanate curing agent and 20-60 parts of a solvent, wherein the elastomer polymer uses hydroxyl-terminated polybutadiene or hydrogenated hydroxyl-terminated polybutadiene as a main chain, hexamethylene diisocyanate as a middle section, and two ends of a molecular chain are blocked by sorbitol polyglycidyl ether.
Specifically, the elastomer polymer is a main film forming material of the coating, the compatibility of hydroxyl-terminated polybutadiene or hydrogenated hydroxyl-terminated polybutadiene in a system can be improved through synthesis modification, the adhesive force of the coating and a PET substrate can be improved, and the self-repairing property and the wear resistance of the coating can be greatly improved.
The elastomer polymer comprises, by mass, 80-106 parts of hydroxyl-terminated polybutadiene or hydrogenated hydroxyl-terminated polybutadiene, 23-45 parts of hexamethylene diisocyanate, 18-39 parts of sorbitol polyglycidyl ether, 0.1-0.4 part of an organobismuth catalyst and 88-120 parts of propylene glycol methyl ether acetate.
The elastomer polymer provided by the invention is a polymer formed by polyurethane reaction of hydroxyl-terminated polybutadiene or hydrogenated hydroxyl-terminated polybutadiene, hexamethylene diisocyanate, sorbitol polyglycidyl ether, an organic bismuth catalyst and propylene glycol methyl ether acetate under certain conditions.
Optionally, the molecular weight Mn of the hydroxyl-terminated polybutadiene or the hydrogenated hydroxyl-terminated polybutadiene is 1000-4500.
Optionally, the fluororesin is one or more of tetrafluoroethylene-vinyl ether resin, tetrafluoroethylene-vinyl ester resin, trifluorochloroethylene-vinyl ether and trifluorochloroethylene-vinyl ester resin, the hydroxyl value of the fluororesin is 50-80 mgKOH/g, such as the east fluorine chemical ZHM-2 or HLR-6 fluororesin, changxing 41011 fluororesin, dajinGK-570 fluororesin and the like, and the addition of the fluororesin can be cross-linked with the elastomer polymer under the action of a curing agent to form a compact network structure, so that the weather resistance of the coating is further improved, and the self-repairing property of the coating can be kept for a long time.
Optionally, the powder is one or more of PTFE micropowder, PVDF micropowder and silicon micropowder. The powder is added into the coating, so that the problem of anti-sticking after the finished product is wound can be avoided.
Optionally, the solvent is one or more of butyl acetate, xylene, ethyl acetate and propylene glycol methyl ether acetate. The solvent is capable of dissolving the organic reactants to form a homogeneous system, so that the components in the coating are fully and uniformly reacted and crosslinked. Solvents of different boiling points are chosen according to the baking temperature to ensure that the coating is not tacky and has sufficient cross-linking cure time.
Optionally, the leveling agent is one or more of an acrylic leveling agent, an organosilicon leveling agent, a fluorine silicon leveling agent and a high boiling point solvent, such as BYK-300, and the leveling agent migrates to the surface of a wet film through limited compatibility to influence the surface tension of the film, so that a smooth and uniform coating is formed in the drying process of the coating, the permeability of the coating to a substrate is improved, and appearance flaws such as spots, marks and the like generated during brushing are reduced.
Optionally, the dispersing agent is one or more of anionic wetting dispersing agent, cationic wetting dispersing agent, nonionic wetting dispersing agent, amphoteric wetting dispersing agent, polymer hyperdispersing agent and controlled free radical hyperdispersing agent, such as Efka PU 4010, and the dispersing agent can improve the surface property of powder particles, adjust the mobility of the powder particles, thereby improving the stability of the powder and avoiding flocculation sedimentation.
Optionally, the antioxidant is one or more of hindered amine, hindered phenol, phosphite ester, thiodipropionate and thiols, in particular 1010 or 168 antioxidants, and the addition of the antioxidant can delay or inhibit the thermal oxidative decomposition of the elastomer polymer, delay the aging of the polymer and prolong the service life of the polymer because the photovoltaic backboard is used under outdoor high-temperature conditions for a long time.
Optionally, the UV auxiliary agent is divided into two types, namely organic and inorganic, wherein the organic is one or more of salicylate, benzophenone, benzotriazole, substituted acrylonitrile and triazine, the organic UV auxiliary agent can absorb ultraviolet rays and stably generate free radicals to prevent organic components in the coating from being damaged and degraded by the ultraviolet rays, the inorganic UV auxiliary agent is one or more of nano zinc oxide and nano titanium dioxide, the inorganic UV auxiliary agent can shield ultraviolet rays, the size between nano particles is equal to or smaller than that of light waves, and the light absorption is obviously enhanced due to the increase of the interval between a conduction band and a valence band caused by the size effect. The addition of the UV auxiliary agent can effectively protect the molecular chains of the elastomer polymer and other components in the coating, so that the molecular chains are not easy to break, the problems of yellowing, cracking, stickiness and the like of the coating are avoided, and the self-repairing property of the coating is further improved.
The polyisocyanate curing agent is one or more of HDI trimer, H6XDI addition product and XDI addition product, each molecule of the polyisocyanate curing agent has more than two-NCO active groups, and can react with-OH functional groups of elastomer polymers, fluororesin and the like in the coating component to form a reticular cross-linking structure, and meanwhile, part of-NCO can also form chemical bonds with polar functional groups on a substrate to improve the adhesive force of the coating, and the self-repairing property of the coating can be stably maintained for a long time due to the reactive cross-linking characteristic of the curing agent.
In another aspect, as shown in FIG. 1, the invention provides a preparation method of a self-repairing coating for a photovoltaic backboard, which comprises the following steps of mixing a solvent and a dispersing agent, sequentially adding powder and an inorganic UV auxiliary agent, stirring and dispersing to enable the powder to be stably suspended and not to precipitate, preparing a dispersion slurry, mixing an elastomer polymer, a fluororesin, a leveling agent, an antioxidant and an organic UV auxiliary agent, adding the dispersion slurry, stirring and dispersing to prepare a semi-finished coating, adding a polyisocyanate curing agent into the semi-finished coating, stirring and dispersing to prepare a finished coating, coating the finished coating on the surface of a PET sheet Tu Pin subjected to corona treatment, baking and curing to form a film, and curing to obtain the self-repairing transparent backboard outer coating.
The preparation method of the elastomer polymer comprises the steps of adding propylene glycol methyl ether acetate into a reaction container, heating to 90-100 ℃, sequentially adding hydroxyl-terminated polybutadiene or hydrogenated hydroxyl-terminated polybutadiene and an organic bismuth catalyst, stirring and dispersing to obtain a pre-dispersion liquid, adding hexamethylene diisocyanate into the pre-dispersion liquid, carrying out heat preservation reaction to obtain a pre-reaction liquid, heating the pre-reaction liquid to 105-110 ℃, adding sorbitol polyglycidyl ether, and stirring for reaction to obtain the elastomer polymer.
Specifically, the reaction mechanism for preparing the elastomeric polymer is as follows:
Example 1
Continuously introducing nitrogen into a reaction kettle, removing air and water vapor, adding 93 parts of propylene glycol methyl ether acetate into the reaction kettle, heating to 95 ℃, sequentially adding 89 parts of hydroxyl-terminated polybutadiene and 0.3 part of organic bismuth catalyst, stirring for 0.5h at 300r/min to uniformly disperse the hydroxyl-terminated polybutadiene and the organic bismuth catalyst, after the temperature of the reaction kettle is stable, adding 31 parts of hexamethylene diisocyanate into the reaction kettle at one time, keeping the stirring speed and the reaction temperature for reacting for 1.5h to fully react, continuously heating to 110 ℃, adding 21 parts of sorbitol polyglycidyl ether into the reaction kettle at one time, keeping the stirring speed and the reaction temperature for 2.5h, sampling, testing NCO content by a titration method (di-n-butylamine), taking the NCO content as a reaction end point when the NCO content is less than or equal to 0.1%, naturally cooling, and discharging and packaging for later use.
Example 2
Continuously introducing nitrogen into a reaction kettle, removing air and water vapor, adding 88 parts of propylene glycol methyl ether acetate into the reaction kettle, heating to 90 ℃, sequentially adding 89 parts of hydrogenated hydroxyl-terminated polybutadiene and 0.2 part of organic bismuth catalyst, stirring for 0.5h at 400r/min to uniformly disperse the hydrogenated hydroxyl-terminated polybutadiene, after the temperature of the reaction kettle is stable, adding 35 parts of hexamethylene diisocyanate into the reaction kettle at one time, keeping the stirring speed and the reaction temperature for reacting for 1h to fully react, continuously heating to 103 ℃, adding 18 parts of sorbitol polyglycidyl ether into the reaction kettle at one time, keeping the stirring speed and the reaction temperature for 2h, sampling, testing the NCO content by adopting a titration method (di-n-butylamine), taking the NCO content as a reaction end point, naturally cooling, discharging and packaging for later use.
Example 3
Continuously introducing nitrogen into a reaction kettle, removing air and water vapor, adding 120 parts of propylene glycol methyl ether acetate into the reaction kettle, heating to 100 ℃, sequentially adding 89 parts of hydrogenated hydroxyl-terminated polybutadiene and 0.4 part of organic bismuth catalyst, stirring for 0.5h at 200r/min to uniformly disperse the hydrogenated hydroxyl-terminated polybutadiene, after the temperature of the reaction kettle is stable, adding 45 parts of hexamethylene diisocyanate into the reaction kettle at one time, keeping the stirring speed and the reaction temperature for reacting for 2h to fully react, continuously heating to 108 ℃, adding 39 parts of sorbitol polyglycidyl ether into the reaction kettle at one time, keeping the stirring speed and the reaction temperature for 3h, sampling, testing the NCO content by adopting a titration method (di-n-butylamine), taking the NCO content as a reaction end point, naturally cooling, discharging and packaging for later use.
Example 4
Continuously introducing nitrogen into a reaction kettle, removing air and water vapor, adding 115 parts of propylene glycol methyl ether acetate into the reaction kettle, heating to 93 ℃, sequentially adding 89 parts of hydroxyl-terminated polybutadiene and 0.1 part of organic bismuth catalyst, stirring for 0.5h at 500r/min to uniformly disperse the hydroxyl-terminated polybutadiene and the organic bismuth catalyst, after the temperature of the reaction kettle is stable, adding 23 parts of hexamethylene diisocyanate into the reaction kettle at one time, keeping the stirring speed and the reaction temperature for reacting for 1.8h to fully react, continuously heating to 105 ℃, adding 27 parts of sorbitol polyglycidyl ether into the reaction kettle at one time, keeping the stirring speed and the reaction temperature for 2.7h, sampling, testing NCO content by a titration method (di-n-butylamine), taking the NCO content as a reaction end point when the NCO content is less than or equal to 0.1%, naturally cooling, and discharging and packaging for later use.
Example 5
45 Parts of butyl acetate solvent and 0.05 part of polymer type hyperdispersant are mixed and stirred uniformly, 2.25 parts of PVDF micro powder and 2.25 parts of silicon micro powder and 0.15 part of nano zinc oxide are sequentially added, and in the feeding process, the rotating speed of a stirrer is gradually increased to 2000 revolutions per minute and kept for 20 minutes, so that powder is dispersed uniformly, and the powder is suspended stably without precipitation, thus the preparation of dispersion slurry is completed.
140 Parts of the elastomer polymer prepared in the example 1, 36 parts of fluororesin, 0.45 part of acrylic leveling agent, 0.3 part of hindered phenol antioxidant, 3.375 parts of triazine and 1.125 parts of benzotriazole organic UV auxiliary agent are mixed and dispersed at a high speed of 1000 rpm for 10min, and then the dispersion slurry is added, and the high speed of 2000 rpm is carried out for 45min, thus obtaining the paint semi-finished product.
And (3) adding 38 parts of polyisocyanate curing agent into the semi-finished paint, stirring for 10min at 1000 r/min, regulating viscosity to obtain the finished paint, coating the finished paint on the surface of the corona-treated PET sheet Tu Pin, baking for 2min in a 150 ℃ oven, performing corona treatment at 4.5kW corona intensity, and curing for 48h at 60 ℃.
Example 6
And (3) adding 24 parts of butyl acetate and 24 parts of PMA serving as solvents into 0.1 part of polymer type hyperdispersant, mixing and stirring uniformly, sequentially adding 1.875 parts of PVDF micro powder, 1.875 parts of PTFE micro powder and 3.75 parts of silicon micro powder and 0.12 part of nano zinc oxide, and gradually increasing the rotating speed of a stirrer to 2000rpm and keeping for 10min in the feeding process to uniformly disperse powder, and stably suspending without precipitating, thereby completing the preparation of the dispersion slurry.
122 Parts of the elastomer polymer prepared in the example 2, 29 parts of fluororesin, 0.5 part of acrylic leveling agent, 0.45 part of hindered phenol antioxidant and 6 parts of triazine organic UV auxiliary agent are mixed and dispersed at a high speed of 1000 revolutions per minute for 30 minutes, and then the dispersion slurry is added, and the mixture is dispersed at a high speed of 2000 revolutions per minute for 60 minutes, so that a coating semi-finished product is obtained.
Adding 42 parts of polyisocyanate curing agent into the semi-finished paint, stirring for 10min at 1000 r/min, regulating viscosity to obtain the finished paint, coating the finished paint on the surface of a PET sheet Tu Pin subjected to corona treatment, baking for 2min at 160 ℃ in an oven, curing for 48h at 60 ℃ after corona treatment at 4.5kW of corona intensity.
Example 7
Mixing 32 parts of PMA solvent and 0.07 part of polymer hyperdispersant, stirring uniformly, sequentially adding 2.17 parts of PTFE micro powder and 4.33 parts of silicon micro powder and 0.1 part of nano titanium dioxide, and gradually increasing the rotating speed of a stirrer to 2000 rpm and keeping for 30min in the feeding process to ensure that the powder is uniformly dispersed, and stably suspending without precipitation, thus completing the preparation of the dispersion slurry.
132 Parts of the elastomer polymer prepared in the example 3, 25 parts of fluororesin, 0.4 part of organosilicon leveling agent, 0.36 part of hindered phenol antioxidant, 4.58 parts of triazine and 0.92 part of salicylate organic UV auxiliary agent are mixed and dispersed at a high speed of 1000 rpm for 30min, and then the dispersion slurry is added, and the mixture is dispersed at a high speed of 2000 rpm for 30min, so that the coating semi-finished product is obtained.
And (3) adding 38 parts of polyisocyanate curing agent into the semi-finished paint, stirring for 10min at 1000 r/min, regulating viscosity to obtain the finished paint, coating the finished paint on the surface of the PET sheet Tu Pin subjected to corona treatment, baking for 2min at 160 ℃ in an oven, curing for 48h at 60 ℃ after corona treatment at 4.5kW of corona intensity.
Example 8
And in the feeding process, the rotating speed of a stirrer is gradually increased to 2000 rpm and maintained for 20min, so that powder is uniformly dispersed, stably suspended and not precipitated, and the preparation of the dispersion slurry is completed.
45 Parts of the elastomer polymer prepared in the example 4, 10 parts of fluororesin, 0.3 part of acrylic leveling agent, 0.2 part of hindered phenol antioxidant, 2.1 parts of triazine and 1.3 parts of benzotriazole organic UV auxiliary agent are mixed and dispersed at a high speed of 1000 rpm for 10min, and then the dispersion slurry is added, and the mixture is dispersed at a high speed of 2000 rpm for 45min, so that the coating semi-finished product is obtained.
Adding 25 parts of polyisocyanate curing agent into the semi-finished paint, stirring for 10min at 1000 r/min, regulating viscosity to obtain the finished paint, coating the finished paint on the surface of a PET sheet Tu Pin subjected to corona treatment, baking for 2min at 150 ℃ in an oven, curing for 48h at 60 ℃ after corona treatment at 4.5kW of corona intensity.
The coatings prepared in the examples above were subjected to relevant performance tests and the data are summarized in table 1.
Table 1 summary of the performance data for the coatings prepared in the examples
As can be seen from the data in Table 1, the transmittance of the transparent back sheet prepared in each example was substantially the same as that of glass and slightly higher than that of the coated and composite back sheet, and the transparent back sheet prepared in each example had thermal repair properties in terms of self-repairing, whereas the conventional back sheet did not have self-repair properties, and the present invention was thermally repaired against scratches caused by outdoor use and worker-installation operations.
In summary, according to the self-repairing coating for the photovoltaic backboard, the coating has the self-repairing characteristic through the synthetic application and the formula design of the self-repairing material, so that the abrasion resistance of the outer coating of the transparent backboard is improved.
With the above-described preferred embodiments according to the present invention as an illustration, the above-described descriptions can be used by persons skilled in the relevant art to make various changes and modifications without departing from the scope of the technical idea of the present invention. The technical scope of the present invention is not limited to the description, but must be determined according to the scope of claims.