Preparation of fluorocarbon-nano self-cleaning powder coatings.

Li Station Iron, Guo Yetian, Lu Oriental
Xuzhou Zhengling Coating Engineering and Technology Research Center
Guide using homemade perfluoro polyether polyester resin and active nanoAl2O3 particles, prepared F-C nano self-cleaning powder composite coating.
by scanning electroscope, contact angle tester, etc. , the coating surface is F elements of the nanomicroscopic structure, contact angle is greater than 150 degrees. Experiments show that this F-C nano-cleaning coating has excellent weather resistance, strong alkaline and obvious ultra-hydrophobic

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Exinception
Polyester powder coating does not use organic solvents, with energy conservation and environmental protection, storage stability, easy coating process, easy to obtain thick coating and other advantages, after decades of development and application, people's research on polyester powder coating is on the rise.
design of new weather-resistant, viscous and self-cleaning powder coatings is of great significance in theory and practical application.
According to the principle of super-hydrophobic and self-cleaning effect of lotus leaf surface, combined with the characteristics of milk protrusion of the micron structure of the lotus leaf surface and the microscopic structure of the surface wax crystal, it is recognized that the rough surface composed of low surface free energy material should have high hydrophobic properties.
In this way, we modeled on the microstructure of the lotus leaf surface, researched and developed new materials in the field of powder coating, and developed new coating methods and processes to prepare fluorocarbon-nano-self-cleaning powder coatings for self-cleaning coatings as the goal.
generally defines normal water contact angles of <10 degrees, <5 degrees for ultra-hydrophobic water, >90 degrees for hydrophobic water, and >150 degrees for super-hydrophobic water.
Self-cleaning coating not only has a very low surface energy, but also the coating surface must form nano-size geometry (such as between convex and concave) interface structure, so that the surface of the material presents an extraordinary dual dredging, can prevent oil or water from direct contact with the surface of the material, in order to achieve ultra-hydrophobic effect.
fluorocarbon-nano self-cleaning powder coating developed using the company's homemade perfluoroform ether modified polyester and active nanoAl2O3 particles.
The introduction of macromolecule perfluoropolyther and active nanoAl2O3 particles in the coating structure, the F-C bond of perfluoropoether has a very low surface energy and the small size effect of active nanoparticles, showing abnormal dual dredging on the coating surface.
Inorganic dust in the air generally has a certain polarity, in the super-hydrophobic surface can not form a strong adsorption, easy to be washed away by rain;
even if the coating is absorbed by organic matter, can also use nanoparticles super-strong photocatalytic activity, and eventually the organic matter into CO2, H2O, H2SO4, HNO3 and other easily washed matter. The coating surface structure and self-cleaning principle is similar to that of lotus leaves, ensuring that the coating surface is as clean as new.experimental method
1.1 Preparation of active nano-Al2O3 particles
dispersed nano-Al2O3 in a weakly acidic ethanol solution, adding 4% weight perfluorooctyl-triethylsilane, reflow reaction 2 h.
2% weight epoxy silane coupled agent after cooling and continue stirring reaction 2 h. Decompression distillation, stripping of solvents from the system, drying in a vacuum drying tank, and obtaining reactive nanoAl2O3 particles.
1.2 Hydroxyl PFPE Preparation
reacts perfluoroEde to methanol with a molecular weight greater than 3000, produces perfluoroEthyl acetate and restores it in a specific catalytic system, synthesizing perfluoroEther with an end-of-ch2OH.
FTIR: 3380 cm-1 -OH, 2955 cm-1 -CH2
1.3 PFPE-polyester modified
adds all reactants such as perfluoro polyetherol, benzoic acid, methylphenidate, hexic acid, catalyst, etc. to the reactor, gradually heating up to 210 degrees C dehydrated ester under nitrogen protection, Then heat up to 240 degrees C to continue dehydration esterification.
when the acid value of the reactant drops below 10, the reaction continues under reduced pressure and the low boiling point is removed. Then, when the reaction temperature drops to 200 degrees C, add benzodiacycline and phthalates, and at 190 degrees C, react l to 1.5 h, to obtain a pluoro-based perfluorolyther modified polyester resin.
1.4 Fluorocarbon-nano-self-cleaning powder coatings
will be active nano-A12O3 particles and PFPE-modified polyester resins, curing agents, leveling agents, pigments, additives Such as a certain proportion of weighing, added to the high-speed mixer mixed 5 to 10 min, the use of double screw extruder melt extrusion, by pressing, crushing, screening, the production of F-C-nano self-cleaning powder coating.
1.5 F-C nano-cleaning powder coating preparation and symptoms
the above-mentioned active nano-A12O3 particles of PFPE-polyester powder coating using electrostitectrectrulation spray equipment applied to the pre-blast treatment and zinc-based coating of the metal substrate.
heating 15 min curing in a 200-degree-C airflow drying tank. Naturally cooled to room temperature, placed 24 h, to determine the performance of the coating.
the thickness of the coating is measured by a 6008B (German BYK) double probe thickness meter, scanned by a JSM-5600 scanning electron microscope, which is called AB300 (Japan), and a contact angle meter is used to determine the contact angle of water on the coating surface.
the chemical composition of the coating surface is indicated by the PHI5702 X-ray electron energy spectrum (XPS) instrument, and the properties of gloss and impact resistance are determined according to the current national standard requirements. results compared to the performance of the
2.1 F-C nano self-cleaning powder coating with the polyester powder coating
as a comparative test, the same ratio of polyester resin powder coating and F-C nano self-cleaning powder coating in the same process conditions prepared into a coating, the performance shown in Table 1.
can be seen that both coating coatings have high performance. Compared to polyester powder coating, F-C nano-self-cleaning powder coatings are slightly less adhesive than polyester powder coatings. Bending experiments show that F-C nano-self-cleaning powder coatings have higher flexibility.
2.2 Effect of the amount of active nano-A12O3 particles on the surface contact angle of the coating
adding different amounts of active nano-Al2O3 particles to the powder coating, and the contact angle of the coating surface to water is shown in Table 2.
can be seen from Table 2, with the increase in the amount of active nanoparticles, the contact angle of the coating surface to water increased sharply, and the hydrophobicity of the coating increased.
4%, the contact angle of the coating to water can be increased from 78 to 136 degrees. When the amount of active nanoparticles is 10%, the contact angle of the coating to water can reach 165 degrees, similar to the contact angle of the lotus leaf surface (Figure 1), with ultra-hydrophobic properties.
increase the amount of active nanoparticles, the contact angle of the coating is reduced, and the quality of the coating is poor. Therefore, in order to obtain a self-cleaning polyester coating with ultra-hydrophobic, the amount of active nanoparticles should be controlled at 8% to 15%.
2.3 Effect of perfluoroEDE dosing on the contact angle of the coating surface
The content of PFPE in perfluoroform ether modified polyester resin has a greater impact on the surface performance of the powder coating, Figure 2 shows the shape of the droplets formed by water on the coating surface of the PFPE modified polyester powder coating at different contents.
can be seen from Figure 2, the powder coating surface prepared from pure polyester resin has a certain hydrophobility, water droplets spread quickly on its surface, contact angle 78 degrees.
water in the PFPE content of 8% and 10% of the coating surface is difficult to spread, can form a bright liquid beads, indicating that the addition of perfluoropolyther has a high hydrophobic, water on its surface contact angle of 120 degrees and 135 degrees, respectively. Table 3 shows the surface contact angles of different contents of perfluoroform ether modified polyester resin powder coatings.
also can be seen from Table 3, with the increase in the amount of perfluoropolyther, the surface of the coating to the water contact angle increased sharply, the hydrophobicity of the coating increased. An 8% addition increases the contact angle of the coating to water from 78 to 120 degrees.
when the amount of perfluoroETHER is 10%, the contact angle of the coating to water can reach 135 degrees, and then increase the amount of perfluoroform ether, the surface contact angle of the coating changes little.
it is more appropriate to control the dosing of perfluoroform ether at 8% to 10%. The chemical elements on the surface of the PFPE modified polyester resin powder coating were tested on the X-ray photoelectronic spectrometer, and the results are shown in Figure 3.
, the Fe signal of the substrate is not detected on its surface, indicating that the substrate is covered with a good coating. There is a strong F signal in the map, indicating that the coating surface is rich in perfluoropolyther F elements, with strong hydrophobic and oil-pumping functions, as shown in Figure 4.
conclusions and prospects
in the process of preparing fluorocarbon-nano self-cleaning powder coating, the use of large molecule perfluoroform ether, control PFPE dosing in 8% to 10%.
to introduce it into the molecular structure of polyester resin, synthetic PFPE modified polyester resin, with the dosage should be controlled at 8% to 15% active nano-A12O3 particles, crosslinkers, pigments, fillers, additives processed together to form a new F-C nano-cleaning powder coating material, coating to water contact angle of more than 150 degrees, coating with ultra-hydrophobic.
its base PFPE modified polyester contains CF bonds, easy to form chemical bonds with active nano-A12O3 particles, so that the nano-coated membrane structure is more solid.
PFPE modified polyester has far superior acid resistance, alkali resistance, corrosion resistance, weather resistance and friction coefficient is small, oil repugnant, water repugnant, anti-stick, anti-pollution and other excellent performance, combined with active nano-A12O3 particles formed by F-C nano-self-cleaning powder composite coating.
has a wide range of applications in anti-corrosion, weather-resistant transportation facilities, transmission facilities, water pipeline facilities, outdoor communication facilities and other coatings.
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