Light curing automotive coatings - the highest level of paint (3)
(four) light curing powder coatings. UV curing powder coatings combined advantages of powder coating and UV curing coating, it can be used not only in the metal, also can be used for plastic and wood products and other heat sensitive components, greatly expanded the scope of use of powder coating so it has great potential in car service, attention. The frame and the wheel rim of the automobiles can be used as a powder coating to replace the original paint. The metal frame on the car to bear stone, contamination, blisters and other violations, general first by electrophoresis, but the electrophoretic paint color choices are restricted and usually a stripe paint disease, in order to improve the decorative color, can make up for UV curing powder coatings. The combination of the two can achieve satisfactory results, powder coatings can give excellent decorative. Wheel rim coatings manufactured by Aluminum Alloy have high requirements for coating, coating the rim of traditional by thermosetting powder coating as a primer, and then the middle layer flash effect, finally is transparent finish. Now these three layers of paint can be replaced by light curing coating.
Two, three-dimensional light curing equipment and technology
The three-dimensional () parts of different shapes and sizes, angles, bending, edges, and concave and convex conditions need to be projected onto all surfaces, and there should be enough energy and sufficient energy for the light curing of the three-dimensional (3D) component. General lighting lamps and reflectors composed by the reflector, beam projected to gather the utensils, the reflector is generally elliptic or parabolic shape, using an oval shade, the first focus of the ellipse in the lamp, lights in the second focus focus on forming a narrow beam of high irradiance. But due to the light divergence, from this point, the irradiance decreased rapidly. The use of parabolic lampshade, UV light can be equal in a wide range, but low irradiance and increase the shadow on three-dimensional objects.
In order to fully cure the entire surface, need to take some measures: one is to improve the formation of elliptical shape of lampshade, changing focus light, making it from the lamp surface further, make the focal plane of a wider, although this will reduce the peak value of high radiation, but can make the light intensity is relatively uniform, in the light from distant places to get enough radiation, while maintaining the advantages of aggregation and astigmatism, reduce the shadow; two is to optimize the formula, coating absorption to light emission spectra and phase matching; three is to optimize the process conditions, UV light projected onto the object body energy to match the processing speed; photosensitive coating and the thickness of the coating should be optimized, so that the surface coating is completely cured in light intensity range can be changed.
Of course, there are special requirements for the 3D curing device, according to the size and shape of the object, the object is vertical or horizontal, whether by rotation. The shadow of potential sites get actual irradiation production line design. In order to achieve the requirement of light curing energy and the adjustment of cure rate, it is an important method to put the lamp on the robot. The use of robots has many advantages, many of the fixed light source can not be irradiated to the part can be effectively irradiated. As mentioned before, in the glass fiber reinforced plastic coating and light curing need to have a large space of three-dimensional coating and curing device, which is also a challenge.
Three, dual hybrid curing application
For some parts, in any case design curing device and a light source, there are some parts of the light intensity can not reach or cannot meet the requirements of coating, therefore UV curing coating is not purely to meet the requirements of coating. In order to solve the problem of the development of UV curing and heat curing method seems to be offset by the advantages of light curing, but this is the impassable problem. In spite of this, there are some advantages of hybrid curing than pure heat curing, the curing temperature is low and the curing time is short. Because most objects in the light have been hard work, only a few parts of the wet, thus reducing the possibility of contamination by objects.
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