The continuous research for innovative technical solutions and the cooperation with various companies leaders in the coating plants production have allowed Tecnocolor to formulate UV products that satisfy the most exigent requests in the industrial coating market.
Characteristics of the base components used to obtain UV Rays Curing products
The components that allow the coating film to be applied and cure through UV Rays are basically the following:
- functionalized olygomers;
- multifunctional Mono-monomers;
The choice of each and everyone of these components has a relevant role in order to obtain the wished aesthetic, mechanical, chemical-physical characteristics of the coating film.
UV Rays Curing Coatings produced by Tecnocolor
Tecnocolor produces UV Rays curing coatings called “UVcolor” of series 32000, formulated with the following polymers:
- unsaturated polyesters;
- epoxy acrylics;
- urethane acrylics;
- polyester acrylics;
- vinyl acrylics;
- hydro-soluble emulsions.
Our UV curing paints guarantees also a good
resistance to the humidity, usually a problem with this kind of paints. Our
UV curing paints guarantees also the marcability of the surface after the UV
curing. This is a good advantage for who works with our technology on the
cosmetic market or packaging market in general.
Application of UV Rays Curing Coatings
Tecnocolor has set-up a wide range of bright and opaque topcoats that can be:
- roll applied;
- spray applied;
- film applied;
- flow coating applied (for auto proiectors on BMC, cataphoretic pretreatment
UV Rays Curing Coatings with 100% of dry residual
It is possible, for certain types of applications (for example the
coatings of edges of the tables on ABS, PVC or PS or the painting of the
fishing rods), to formulate and produce UV rays curing coatings with 100 % of dry residual solving the problems of the dangerous emissions in the environment, maintaining optimal adhesion, elasticity, mechanical and physical resistance characteristics.
Water based UV Rays Curing Coatings
The curing technology utilizing UV Rays irradiation of water based products has become a realistic alternative to UV 100 % dry residual presenting toxicity problems due to the presence of acrylic monomers and to UV solvent based systems. The products are based on urethane acrylic olygomers or water based acrylic polyesters. In these coatings the monomer reactive diluent or solvent is substituted by water. Obviously before hardening of the film under UV irradiation, the removal of the aqueous phase present in the product (at least 3’ at 60 °C) becomes necessary.
A UV water based system presents the following advantages:
- product viscosity control with running water;
- non need for solvents;
- washing of coating dedicated lines with water;
- use of traditional coating instrumentation to apply coating;
- products are non-flammable;
- no presence of acrylic monomers.
Tecnocolor produces for all the world the UV
curing water based paints here following listed:
base and top coats for high vacuum metallization process of plastic
- coatings for plastic materials (ABS, PC, PP flamed, etc.)
- coatings for metallic materials (Fe, zama, etc.)
- coatings for glass
UV Rays and Coating polymerization
UV rays are particularly actinic and can start chemical reactions. The UV radiation has a band of its physical spectrum in the region of resonance of the double bond C=C (186-240 nm) and this is clearly very important for the polymerization of the resins present in the coatings.
UV Rays Generating Lamps
The UV generating sources are various. As per what regards artificial UV generating sources the market offers two principal types of lamps:
- Mercury Vapour (Hg)
- Gallium Vapour (Ga)
The most innovative systems do allow the power control of the lamps (usually modulable from 80 to 160 W/cm2). It would be opportune checking the effectively delivered energy with a radiometer (J/cm2) in order to allow a correct and complete polymerization of the applied coating film.
“Dual Cure” System
“Dual Cure” means double polymerization. The applied coating film is polymerized by UV rays or by a heating source that can spring, depending on the cases, from both the heat generated by the UV lamps themselves or by IR medium waves.
This allows to definitely solve the problem regarding the tridimensionality of the pieces to be coated that could create certain issues concerning the setting of the coating. In fact light propagates on straight lines and the absorbed energy by the film varies depending on the incidence angle of the irradiated light ( the UV rays energy is inversely proportional to the square of the distance of the piece from the light source).
With this system all zones of the same piece are perfectly polymerized even in those areas that to not belong to surfaces parallel to the UV rays direction.
Pre and Post Metallization UV Rays Curing Coatings
Tecnocolor produces a range of base coatings and UV curings for high vacuum metallization.
During the set-up of these products Tecnocolor has foreseen the possibility to utilize mixed cycles of traditional pre metallization and UV curing post metallization coatings so to supply the widest productivity elasticity.
Influence of the colour of the basecoats or materials to be coated on the curing of a transparent UV coating.
It is important to consider the colour of the base when a transparent coating is to be applied. The main problem to be faced is the absorbing index of the UV rays by the different colours. For example a white base would absorb less energy than a black one. This strongly influences the curing of the coating: for example in the case of a black ABS to be coated with a transparent coating the colour of the base will favour the polymerization.
Particularly critical is the situation concerning the post UV curing post metallization coatings, in fact the ultra violet gets reflected by the specular aluminium film deposited in the vacuum cap needing an increased energy level to grant the curing of the
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demonstrations, researches and samplings.