Powder coating
It is a new solvent-free 100% solid powder coating. It has two categories: thermoplastic powder coatings and thermosetting powder coatings. The coating is made of special resin, pigments and fillers, curing agent and other additives in a certain proportion, and then it is hot extruded, crushed and screened. They are stable in storage at room temperature, coated by electrostatic spraying or fluidized bed impregnation, and then heated, baked, melted and solidified to form a smooth and bright permanent coating, thus achieving the purpose of decoration and anticorrosion. Features:
1, this product is non-toxic, solvent-free, and has no volatile toxic substances, so there are no public hazards such as poisoning, fire, and "three wastes" discharge, which fully meets the requirements of the national environmental protection law.
2. The utilization rate of raw materials is high, and the overspray powder can be recycled, and the utilization rate is over 99%.
3. After pretreatment of the coated object, a coating film with sufficient thickness can be obtained by one-time construction without primer, which is easy to realize automatic operation, has high production efficiency and can reduce the cost.
4. The coating is compact, with good adhesion, impact strength and toughness, high corner coverage and excellent chemical corrosion resistance and electrical insulation.
5. The storage and transportation of powder coatings are safe and convenient.
Construction technology and requirements of powder spraying: the so-called powder electrostatic spraying is the principle of using high-voltage electrostatic corona electric field. The high-voltage negative electrode is connected to the metal guide mark on the head of the spray gun, and the sprayed workpiece is grounded to form a positive electrode, so that a strong electrostatic field is formed between the spray gun and the workpiece. When compressed air is used as carrier gas to send powder coating from powder supply barrel to the guide rod of spray gun through powder tube, dense negative charge is generated near the guide rod due to corona discharge caused by connecting high voltage negative electrode, which makes the powder negatively charged and enter the electrostatic field with high electric field strength. Under the dual action of electrostatic force and carrier gas, the powder uniformly flies to the surface of the grounded workpiece, forming a powder layer with uniform thickness, and then heating and curing to form a durable coating film. Construction requirements for pretreatment, drying and dewatering, spraying, inspection, baking and finished product inspection General requirements for powder spraying.
(1) In order to give full play to the characteristics of powder coating and prolong the service life of the coating, the damaged coating surface should be strictly pretreated first.
(2) When spraying, the coated object must be completely grounded to increase the spraying efficiency of powder coatings.
(3) For coated objects with large surface defects, conductive putty should be painted to ensure smooth and flat coating.
(4) The sprayed object needs to be cured by heating. The curing conditions are based on the technical indexes of powder products, but the curing temperature and time must be fully guaranteed to avoid quality accidents caused by insufficient curing.
(5) Check immediately after powder spraying. If defects are found, they should be dealt with in time. If defects are found after curing, the scope is small and only partial, and the surface decoration of the coated object can be repaired after dilution with acetone. If the scope is large, affecting the surface quality, it should be sanded, sprayed again or removed with paint remover, and then removed.
(6) The recovered powder must be screened to remove impurities, and then mixed with new powder in a certain proportion.
(7) The powder supply barrel, powder spraying room and recovery system should avoid the pollution of other powders with different colors, so they must be purged every time they change color.
2. Construction requirements of fine powder spraying: Fine powder has the characteristics of beautiful appearance, three-dimensional effect and strong decorative effect, but its construction technology requirements are strict.
(1) When spraying powder, the input air pressure should not be too large, and it is generally better to control it at 0.5- 1.5 kg/cm2. Too high air pressure will lead to poor pattern definition or pockmarks. Electrostatic voltage should not be too high, generally controlled at about 60-70Kv. If the voltage is too high, the powder attached to the surface of the workpiece will rebound and produce pits. Poor leveling property and the like.
(2) Pay attention to ensure the thickness of the coating when spraying powder. The coating should generally be controlled between 70- 100μm, which is beneficial to the formation of obvious patterns and large patterns. If the coating is thin, the pattern is not obvious and the pattern is small. At the same time, defects such as pockmarked surface and exposed bottom will appear.
(3) When curing, it must be baked at the specified temperature and time. If the temperature is too low and the time is too short, the powder will not be patterned, and the mechanical properties will be greatly reduced because of incomplete curing. In addition, due to the particularity of the production process of artistic pattern powder, the pattern will become smaller or inconspicuous after spraying recycled powder, so it is generally recommended not to use recycled powder of artistic pattern powder. If you want to use it, you must test it. To sum up, although the construction requirements are strict, I believe that as long as the above factors are well grasped in the painting process, the ideal satisfactory effect will be achieved. Storage and use of powder coatings
1, away from fire sources and direct sunlight, and should be placed in a well-ventilated place with a temperature below 35℃.
2. Avoid storing in places that are easily polluted by water, organic solvents, oil and other substances.
3. Don't expose the powder coating to the air after use. Cover or fasten the bag mouth at any time to avoid sundries.
4. Avoid long-term contact with the skin. The powder attached to the skin should be washed with soapy water, and no solvent can be used. Safety of painting construction site
L, equipment used in painting operation should be well grounded to eliminate static electricity.
2. Avoid the phenomenon of endless discharging of the coating machine.
3. In the powder spraying room, the concentration of floating dust should be controlled below the safe concentration as far as possible to avoid the danger of dust fire and explosion.