Characteristics and construction of powder coating

Powder coating is a new type of solvent-free 100% solid powder coating It has two major categories: thermoplastic powder coating and thermosetting powder coating The coating is made of special resin, pigments and fillers, curing agent and other additives, mixed in a certain proportion, and then prepared by hot extrusion, crushing and sieving Under normal temperature, they are stored stably After electrostatic spraying or fluidized bed dip coating, they are heated, baked, melted and solidified to form a smooth and bright permanent film, so as to achieve the purpose of decoration and anti-corrosion Features 1 The product does not contain toxicity, solvents and volatile toxic substances, so there is no problem of pollution such as poisoning, fire and discharge of "three wastes", fully in line with the requirements of 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 more than 99% 3 After the pretreatment of the coated object, the one-time construction can obtain enough thickness of the coating without the need of primer, which is easy to realize automatic operation, high production efficiency and low cost 4 The coating is compact, with good adhesion, impact strength and toughness, high corner coverage, excellent chemical resistance and electrical insulation 5 The storage and transportation of powder coating are safe and convenient The so-called powder electrostatic spraying is to use the principle of high voltage electrostatic corona field A high voltage negative electrode is connected to the metal guide sign at the head of the spray gun, and the sprayed workpiece is grounded to form a positive electrode, so as to form a strong electrostatic field between the spray gun and the workpiece When the powder coating is sent from the powder supply barrel to the guide rod of the spray gun by the compressed air as the carrier gas, Due to the corona discharge generated by connecting the guide rod with the high-voltage negative electrode, a dense negative charge is generated near the guide rod, which causes the powder to take a negative charge and enter the electrostatic field with high electric field strength Under the dual action of electrostatic power and carrier gas, the powder flies evenly to the surface of the grounded workpiece to form a thick and uniform powder layer, which is then heated and solidified to transform into a durable coating Coating construction process flow: pretreatment - drying and moisture removal - spraying - Inspection - baking - Inspection - finished product construction requirements 1 General powder coating construction requirements (1) in order to make the characteristics of powder coating fully play and extend the service life of the coating film, the surface of the damaged coating shall be strictly pre treated first (2) When spraying, the coated object must be completely grounded to increase the spray efficiency of powder coating (3) for the coated objects with large surface defects, conductive putty shall be applied to ensure the flatness and smoothness of the film (4) after spraying, the objects shall be heated and solidified, and the curing conditions shall be subject to the technical indicators of powder products, but the curing temperature and time shall be fully guaranteed to avoid quality accidents caused by insufficient curing (5) check immediately after powder spraying If any defect is found, handle it in time If any defect is found after solidification, the scope is small but not affected The surface of the coating can be decorated It can be repaired by diluting the same color powder with acetone If the scope is large and affects the surface quality, polish it with sandpaper, spray it again or remove the coating with paint remover, and then re Suo powder (6) the recycled powder shall be screened to remove sundries and mixed with new powder in a certain proportion (7) the powder supply barrel, powder spraying room and recovery system should avoid the pollution of powder of different colors, so they should be cleaned every time they change colors Construction requirements for fine arts powder spraying: Fine Arts powder, with the characteristics of beauty, strong three-dimensional sense, decorative effect, etc., but its construction process is strictly required (1) when spraying powder, the input air pressure should not be too large Generally, it is better to control it at 0.5-1.5kg/cm2 Too much air pressure will cause poor pattern definition or some pockmarks Static voltage should not be too high, generally controlled at 60-70kv If the voltage is too high, the powder attached to the surface of the workpiece will rebound and appear pockmarks Defects such as poor leveling (2) pay attention to ensure the thickness of the coating Generally, 70-100 μ M can help to form obvious pattern and larger pattern If the coating is thin, the pattern is not obvious, and the pattern is also small At the same time, there will be defects such as pitting and bottom exposure (3) baking must be carried out according to the specified temperature and time when curing If the temperature is too low and the time is too short, the powder will not form a pattern, and the mechanical properties will be greatly reduced due to incomplete curing In addition, due to the particularity of the production process of art pattern powder, the pattern will be smaller or not obvious change after re spraying with recycled powder, so it is generally recommended not to use recycled powder of art pattern powder It has to be tested if it is to be used From the above point of view, although the construction requirements are strict, it is believed that as long as the above factors are well grasped in the coating process, the ideal satisfactory effect will be achieved The storage and use of powder coating 1 Keep away from fire source and avoid direct sunlight Place it in a well ventilated place with temperature below 35 ℃ 2 Avoid storage in places susceptible to water, organic solvents, oil and other materials pollution 3 The powder coating shall not be exposed in the air at will after use, and the bag mouth shall be capped or screwed tightly at any time to avoid sundries mixing 4 Avoid long-term contact with the skin The powder attached to the skin shall be washed with soapy water and no solvent shall be used The safety of the coating construction site and the equipment used in the coating operation shall be well grounded to eliminate static electricity 2 Avoid the phenomenon of no end discharge of the coating machine 3 In the powder spraying room, the concentration of floating dust shall be controlled below the safe concentration as far as possible to avoid the risk of dust ignition and explosion.