Powder coating develops rapidly in the international market as a new type of coating featuring low pollution, pollution reduction and energy conservation and becomes one of the main varieties that can replace partial solvent based coatings. With the development of industries such as light industry, household appliance, electronic instrument, automobile and corrosion prevention as well as the increasing needs for environmental protection, energy conservation and resource conservation, the requirements on the output, quality and variety of thermosetting powder coatings become higher. Therefore, powder coating develops rapidly as an emerging coating industry. It cannot meet the increasing needs in the industries such as refrigerator, washing machine, electric fan, gas steel cylinder, electrical appliance and meter case in the aspect of quantity, quality, variety and construction and application technology.
Features of Kaluofu Thermosetting Powder Coating
1. Solvent-free, pollution-free, easy transportation, storage and application.
2. Easy construction, applicable to electrostatic spraying and fluidized bed painting.
3. Less consumption per unit area, high economic benefits.
4. Three series of thermosetting powder coating—epoxy powder coating, polyester powder coating, epoxy/polyester powder coating are available.
Epoxy Powder Coating
The epoxy powder coating features high adhesion, strong chemical resistance and good electrical insulation. It is applicable to decorative coating for refrigerators, washing machines, household appliances, instruments and meters as well as anti-corrosion coating for various equipments, pipelines, instruments and meters.
Polyester Powder Coating
Polyester powder coating is applicable to decorative coating of transport vehicles, agricultural machinery, horticultural equipment, bicycles, building windows and doors and other outdoor products owing to its excellent weatherability, ultraviolet resistance, high decoration, hard coating, flexibility and good edge coverage. Curing conditions: 180°C for 15 minutes.
Epoxy/Polyester Powder Coating
The epoxy/polyester powder coating combines the performance of epoxy and polyester powder coating and features strong adhesion, gloss retention, flexibility and good edge coverage. It is applicable to decorative coating of transport vehicles, agricultural machinery, horticultural equipment, bicycles, building windows and doors and other outdoor products. Curing conditions: 180°C for 15 minutes.
Advantages of Kaluofu Powder Coating
It can save working procedures and shorten processing cycle. Generally one-time coating is needed, and thickness can reach 30um-50um. The second coating can be performed according to special requirements.
The powder can be recycled after sieving.
It features high deposition effects on metal surface, and the amount of powder entering the recovery system reduces greatly due to good performance in electric charging.
It can be used immediately after unsealing. The preparation work including viscosity check and dilution is not needed.
Powder coated workpieces can greatly reduce the possibility of damage during transportation and assembly due to high mechanical strength. Film coating can be performed by machines.
A manual spray gun can be used. It is easy to master even for new learners. The automatic control of coating molding can be realized by using the automatic spraying equipment.
Compared with oil paint, this product belongs to noncombustible and nonvolatile material. Therefore, no ventilation equipment is needed.
The space between the spraying and curing areas should be kept away from flames, thereby saving space.
Construction Field: Especially the automatic coating workshop occupies less area than the common painting workshop.
Compared with most of painting equipment, powder coating equipment features reasonable design and can save a large amount of energy.
Powder coating features high rate of edge coverage and no sagging.
Only vacuum cleaners are needed for cleaning the recovery system owing to easy maintenance.
It boasts easy storage, transportation and management for it belongs to solid powder.
Compared with the domestic like products, Kaluofu powder features low curing temperature and energy conservation, the curing time is shortened by half, and the processing capability is nearly doubled.
Pretreatment of Workpieces
he surface pretreatment before powder coating is an important link. To realize high-quality powder coating, the surface of workpieces should be clean, dry and greaseless metal pieces.
Generally the pretreatment is divided into two categories: 1. Mechanical treatment: Sand blasting, sanding, derusting with a metal brush; 2. Chemical treatment: Acid cleaning for oil removal, phosphate or chemical oxidation, solvent degreasing.
Generally the pretreatment includes derusting, degreasing, phosphorization or oxidization. The adhesion and corrosion resistance of coatings can increase due to excellent pretreatment process.
Construction
Powder coating is made according to the requirements of electrostatic spraying. The manual spray gun or automatic production lines consisting of several spray guns can be used for spraying.
Powder coating is fed by a powder supply device and is delivered to the spray gun by airflow. The powder carries electrostatic charges by using a spray gun. The charged powder is absorbed on the earth pieces by virtue of airflow. High voltage: 50-70um. The powder with electrostatic charges absorbed on the workpieces boasts high adhesion and cannot fall off due to general airflow or slight shake. It enters the drying oven or drying tunnel for curing after a careful check. General curing conditions: the workpieces can obtain high performance coating through baking below 180°C for 15 minutes.
Notice:
To guarantee high performance coating, please meet the following requirements during construction:
1. Powder coating should be tightly sealed and stored in a cool and dry place;
2. Please clear all surface contaminants before spraying, and correct pretreatment is required;
3. The compressed air contains no water or oil, and the operating condition of oil-water separators is inspected regularly;
4. The workpiece holder and earthing position should keep good connection;
5. Oven temperature should be uniform and stable and reach the curing conditions;
6. The powder supply device, spray cabinet and recovery system should be clean and pollution-free; 7. Avoid dust and solvent gas.
Coating Fault Treatment
1. Powder cannot be absorbed on workpieces
Powder cannot be absorbed on workpieces due to no high voltage or imperfect earth. Please check and clean the spray gun, regulate voltage and clean all earth points and workpiece holders.
2. Insufficient quantity of powder：
The primary cause is insufficient quantity of powder emitted by the spray gun. Please adjust air pressure, clean or regulate the powder supply system and clear the pipeline.
3. Low gloss or color fading of coating film
The primary cause is a too long baking time, excess temperature or other solvent gas. It is required to shorten time, adjust temperature and remove external gas.
4. Shrinkage cavity and pinhole of coating
The primary cause is improper surface treatment, incomplete removal of oil, polluted air source and residual oil in compressed air. Please check and correct surface treatment of workpieces so as to keep workpieces dry and clean. It is required to regularly open the water drain valve of the oil-water separator or install a multi-stage oil-water separator. Meanwhile, please ensure that no solvent gas exists in working area.
5. Insufficient adhesion and mechanical strength
The primary cause is insufficient curing temperature or ultra-short time, improper surface treatment, over-thick coatings or overbaking. It is required to strictly control the curing temperature and time according to technical indexes, i.e. reaching the curing temperature and time. Meanwhile, please pay attention to coating thickness.
6. Foreign matters
The primary cause is the spray guns, spraying chamber or recovery system and coating workshop under insanitary conditions or improper pretreatment. Please keep the environment clean and strictly inspect the working quality of pretreatment.