Characteristics of fluorescent pigments
The difference between fluorescent pigments and traditional pigments is not only in color, but also in chemistry. Traditional pigments can be organic or inorganic and have very low solubility. Their dispersion generally requires strong shearing. Their particles are generally opaque.
Sunlight fluorescent pigment is strictly a solid solution composed of fluorescent dyes in brittle polymer resin. The latter is grinded and processed into fine powder to become pigment or colorant. The characteristics of its solid solution make it often transparent in application.
Application of fluorescent pigments in powder
1、 Dry mixing method
The dry mixing method is to use the semi-transparent powder resin solidified at low temperature as the base material, add about 6% fluorescent pigment, and then conduct high dispersion, evenly disperse, and screen to form the product powder coating. The powder coating film obtained by this method has bright color, simple production process, and less pigment addition compared with the wet method. However, the appearance of the coating film is not too fine because the pigment is not sufficiently dispersed.
2、 Wet process
In the wet process, resin, curing agent, filler, leveling agent, fluorescent pigment, auxiliary agent and other materials are premixed with a mixer, and then fused and extruded by an extruder, coarse damage, ACM fine damage, and graded packaging. The surface of the coating film obtained by this method is smooth and smooth, but the amount of pigment added is relatively large, and the production cost is high.
Manufacturing skills and coating methods of fluorescent powder coatings
1. Adding about 0.5% (based on the amount of resin) of antioxidant in the formula can significantly improve the bright color of the coating film.
2. Because of the temperature resistance of the fluorescent pigment itself, it is not suitable to withstand high temperature for a long time, so the low temperature curing system should be selected: the extruder barrel and screw temperature should be set as low as possible: the screw speed should be fast to prevent the material from staying in the screw barrel for too long.
3. Avoid excessive baking or secondary baking, otherwise the color of the coating will be deepened.
4. Prevent fluorescent pigments from mixing with additives containing free zinc, magnesium, calcium and iron ions to prevent pigment migration.
2、 Hiding power
1. Add a certain amount of white pigments, such as zinc oxide, titanium dioxide, etc. to the ingredients, which can significantly increase the covering power of the coating film and prevent the color difference caused by uneven film thickness. This method is relatively simple and reasonable,
2. Increase the amount of fluorescent pigment.
3、 Painting method
For the priming of the pre-processed workpiece, white powder coating or non-fluorescent powder coating with the color close to the selected fluorescent powder is generally selected as the primer. The thickness of primer film shall be controlled at 30 μ M, so that the color difference of the substrate can be eliminated and reflected on the surface of the film, and the brightness of the film color can be added together. The new method has one more process, which adds cost and labor, but its brightness cannot be achieved by other methods. When spraying fluorescent powder coating, choose automatic coating machine, so as to obtain better leveling performance.