Light curing automotive coatings - the highest level of paint (2)
(two) automotive topcoat. The most important is the role of automobile paint decoration, in addition to the beautiful appearance, anti oxidation, hydrolysis resistance, scratch resistance, acid rain and gasoline, anti impact, anti thunderstorm and insolation performance also. Now in general is composed of two layers of paint coating, the lower (first) coatings with various pigments such as color pigments, flash pigment (Er Daojiang), the upper coating varnish, which can give the coating high gloss finish and meet various requirements, so it is crucial. It is difficult to use in the first light curing coating paint finish but can be used for transparent varnish. UV curable transparent varnish has the advantages of no solvent, fast curing, high inherent characterization, abrasion resistance, high gloss, high hardness, but it is weather resistant is not very good, this is why it is difficult to be accepted for a long time. Light cured varnish is not only mechanical properties should be reached or more than two cans of polyurethane varnish, but also to achieve a certain weather resistance requirements. Although can add light stabilizer and anti aging agent to improve the coating corrosion resistance performance, but light stabilizers will affect the curing rate, this is a difficult problem to solve, is one of the key problems that hinder the light curing varnish for use in automobiles. In recent years, through the selection of appropriate initiator and UV absorbers and anti ageing agent opened for automotive finish road. The car is generally transparent varnish by light cured acrylic acid polyurethane resin, the photo initiator is BAPO (bisacylphosphinoxide) or Irgacure118 (alpha -hydroxylketone), while adding UV absorbers such as HPT in the formula (hydroxyphenyl-s-rriazine) and the use of hindered amine HALS as the free radical removing agent. The experimental results show that the curing speed and the excellent weather resistance can be achieved by adjusting the suitable components.
(three) auto plastic parts coating. Automotive components have been used in many engineering plastics or polymer matrix composites, they not only need to improve the surface properties of coatings, light curing coatings in this area has a very prominent advantage. The application of light curing in this aspect has been more than ten years of history.
- lampshades: polycarbonate lamp has long been replaced by glass, polycarbonate has easy processing, light weight and flexibility not easily broken and other advantages, but its surface strength is not enough, no resistance and scratch and poor weather resistance, easy to turn yellow, with the light curing coatings can improve the surface properties, so it has been used not only. Save time and coating coating has good resistance to abrasion property of optical, and can meet the requirements of long-term weather resistance.
- mirror: the car mirror is also prepared with plastic, but its surface must have a high reflective performance. In order to achieve this goal, the plastic surface must be treated with UV irradiation for three times. The first plastic to ultraviolet radiation to the surface photochemical reaction increases the surface tension, in order to facilitate the flow of UV curing coating and adhesion, after light curing varnish coating after curing, the plastic surface became flat and easy to metal, metal deposition and vacuum deposition in the box. A layer of light curing coating is needed to be coated on the surface of the plastic surface.
Glass fiber reinforced composite parts: composite materials have been widely used in various parts of the car, in order to protect the surface and beautiful, the use of paint to paint. For example, the aforementioned demonstration car body part of the use of electron beam curing composite materials, while the use of light curing coatings to be modified. One of the key issues in the use of light - curing coatings on a large volume of components is the design of a coating curing chamber to facilitate the overall coating of the body.
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