Powder coatings have been introduced into China since the 1960's. At that time, there were very few application areas, and they were only applied to certain electrically insulated parts.
Since the creation of powder coating, does not contain any added solvents, film conversion rate is high, is conducive to the protection of metal profiles, more and more attention in the world, showing a booming trend.
Powder coating technology is developing rapidly in the domestic and international manufacturing industry due to its inability to utilize solvents, high powder content, ease of construction, and high recycling rate.
1. The type and performance of powder coating on aluminum doors and windows.
There are three types of surface treatment for profiles: powder coating, anodic oxidation and electrophoretic coating, each of which has its own characteristics and occupies a large proportion of the market.
Aluminum-type coatings are represents by acrylic and epoxy types, and are used for corridors and balconies, as well as aluminum frames, doors and windows. At present, the surface treatment of aluminum profile has anodic oxidation, electrophoretic coating and powder coating three kinds of treatment, each kind of surface treatment has its own outstanding characteristics, and is very popular in the market.
There are many kinds of powder coatings for aluminum profiles, and weather-resistant polyester powder coatings are the main materials used for aluminum-type powder coatings.
Termocarboxylic groups have intrinsic molecular weights and acid values, with the range of 2000-8000 being the molecular weight of the termocarboxylic group, and 20 a IOOmgKOH/g being the acid value. These different end-carboxyl groups are used in different coatings, and in epoxy coatings, medium to high acid end-carboxyl groups with acid values of 45-85 are mostly used.
Isocyanuric acid and hydrocarbon-based amides for polyester with and acid value of 20-45 are mostly used in pure polyester powder coatings.
According to different properties, polyester powder coatings have three different classification criteria: one is the exposure test in more than 5 years belongs to the super weathering powder coatings, the other two exposure value of 1-2 years and 2-3 years of the two coatings, respectively, are categorized into the standard weathering powder and improved weathering powder category. The criteria for this classification are known as the Florida exposure test results.
Powder coating operations are good for energy conservation. In conventional anodizing and electrophoresis coating operations, a large amount of electricity is consumed.
2. Powde coating on aluminum profiles notes
There are two different types of fixtures which are used differently, the fixtures are either placed at the ends of the profile or in the middle of the profile.
The fixtures placed at the ends should have a huge load capacity. By loading the profiles in tandem, the profiles have a small mass and a small area, and the fixtures have to increase their load capacity, only in this way can they guarantee a large load capacity.
In the process of using, avoid the contact point between the intermediate fixture and the profile, the contact point will form a defect, reasonable control of the area of the contact point, the size of the defect area and the size of the contact point is related. Intermediate fixture in the vertical placement process, the hanging rod will be attached to a portion of the powder, need to control this part of the powder adsorption.
In the spraying operation, the key operation process is the powder spraying production, reasonable control of the spraying operation process, will be able to improve the quality of the sprayed profiles. In the process workflow, it contains two kinds of operation indexes, one is atomized air, and the other is the amount of powder.
Before the start of powder spraying, you can spray a few times, using the observation method to observe whether the sprayed powder is uniform. Spray gun to maintain a straight line operation of the state, spray powder from the front of the gun to maintain a distance, generally controlled in 10cm to 15cm, the spray powder presents a mist, the profile surface of the spray powder is the performance of this atomization.
The incliation of the spray gun should be maintained in a certain posture, generally for the bias-type movement of the posture, vertical parallel for the arrangement of the spray gun, to ensure that the end is in a horizontal state, to maintain a straight line, the overlap phenomenon should not appear between the spray gun, the upper and lower spray gun to cover all the powder coating, which is the spray gun operation need to pay attention to.
In the whole baking process, need to reasonably control the pressure, so that the pressure is in the atmospheric pressure range, Ikg/cm³ about the pressure is normal.
