Coating technology: Determination of contrast ratio of light colored paint

Key tips: 1 Coating testing instruments and materials: (1) Base material: the base material adopts untreated colorless transparent polyester film with thickness of 30-50 μ m and size of no less than 100mm × 150 mm (2) Paint film applicator: it is required to use a set of paint film applicator that can give a uniform paint film with a wet film thickness of nearly 40-60 μ M The film size is not less than 60mm × 60mm Automatic applicators can also be used to achieve a more uniform coating (3) Reflectometer ( Paint knowledge how about Akzo Nobel Powder Coating Recommended introduction: powder coating is a kind of coating with different form from general coating, which is in powder form It is a new type of coating, because of its own advantages and more and more known by people Let's introduce Akzo Nobel Powder coating Akzo Nobel Powder coating is a cost-effective coating solution, which can be applied to different kinds of products After the treatment of static electricity and fire baking, a tough and durable coating surface will be formed, with the least impact on the environment Since the introduction of this technology, powder coating has been able to continue to maintain the Coating home news: 1 Coating testing instruments and materials: (1) base material: the base material adopts untreated colorless transparent polyester film, with a thickness of 30-50 μ m and a size of not less than 100mm × 150 mm (2) Paint film applicator: it is required to use a set of paint film applicator that can give a uniform paint film with a wet film thickness of nearly 40-60 μ M The film size is not less than 60mm × 60mm Automatic applicators can also be used to achieve a more uniform coating (3) Reflectometer (4) standard plate and template 2 Coating test steps: (1) prepare the substrate on a 6mm thick flat glass plate, drop a few drops of 200 paint solvent oil, and lay the polyester film on it Its wetting degree can make the polyester film stick on the surface of the glass plate with the aid of the surface tension of No 200 paint solvent oil, and there should be no bubble between the polyester film and the glass plate If necessary, a clean white silk cloth can be used to eliminate air bubbles (2) The preparation of polyester film for painting mix the color paint evenly to destroy any thixotropic structure, but no bubbles, and use it immediately According to the required thickness, at one end of the polyester film, pour 2-4ml of color paint along the short line, and immediately use a suitable coater to scrape the paint at a uniform speed to spread the color paint into a uniform coating Three kinds of coaters with different specifications, which can give the wet film thickness in the range of 40-60 μ m, were selected to prepare two films each The coated polyester film is fixed on a flat substrate and dried in horizontal conditions Drying time or baking conditions, depending on the type of sample to be tested, shall be as specified in the product standard (3) The state conditions shall be maintained for at least 24h at 23 ± 2 ℃ and (50 ± 5)% relative humidity before reflectivity measurement, but shall not exceed 168h (4) The reflectance is measured on black and white glass plates (or ceramic plates) by dropping a few drops of 200 paint solvent oil With the help of its surface tension, the coated polyester film is successively adhered to ensure optical contact Then, the reflectivity of each coated polyester film is measured in at least four positions, and the average reflectivity R B (on the blackboard) and R W (on the white board) are calculated respectively, and then the contrast ratio R B / R W of each coated polyester film is calculated (5) The measurement of dry paint film surface density is in the center of dry paint polyester film Depending on the template, use a vertical knife to cut the test piece with the same area as the template, weigh it (accurate to 1mg), and then use the solvent that has no influence on the drying amount of polyester film to remove the paint film After the paint film is completely dried, weigh the quality of polyester film again Calculate the surface density of dry paint film ρ a (g / m m 2): ρ a = (M 2-m 1) / a where: M 1 - mass of unpainted polyester film, G; m 2 - mass of painted polyester film, G; a - area of cut polyester film, mm 2 (6) Calculate the wet film thickness to determine the density of the paint; measure and calculate the nonvolatile content of the paint, and calculate the film thickness (mm) according to the following formula: T = ρ A / ρ a · NV × 105 formula: ρ - the density of the paint, g / ml; ρ a - the surface density of the dry paint film, g / mm; NV - the nonvolatile content,% (7) calculation of the coating rate The coating rate Sr (m2 / L) is the reciprocal of the wet film thickness From the following formula: SR = 1 / T = ρ · NV / ρ a × 10-5, substituting the formula of dry film surface density ρ a, we can get: SR = 1 / T = a · ρ · NV / (m2-m 1) × 10-5 (8) the ratio measurement when the coating rate is 20 m2 / L In the limited film thickness range, the contrast rate and the coating rate are approximately linear functions, so the contrast rate values of six films and the corresponding coating rate values can be combined into a curve, and then the contrast rate when the coating rate is 20 m2 / l can be obtained by linear interpolation It can also be calculated by linear regression Home of coatings is specialized in coatings, diatom mud, paint coating, coating technology, fire retardant coating news and coating, diatom mud, paint coating, coating technology, fire retardant coating decoration knowledge and decoration renderings,