With ELASTOSIL® Color Paste FL UV Fluorescent, the Munich-based chemical company is expanding its portfolio of pigment pastes. The new product is a pourable, translucent pigment dispersion that appears a pale yellow color in daylight. It contains an organic pigment that is highly fluorescent under ultraviolet light. This pigment is excited to emit light at a wavelength of 365 nanometers, emitting blue-violet light with a wavelength of 430 nanometers. The high effectiveness of the pigment means that generally only 0.5 to 2 percent of the pigment paste is required to provide the silicone rubber with a fluorescent marking.
The liquid component of the dispersion is a silicone fluid, as is also used in liquid and other addition-curing silicone rubber compounds. It contains vinyl groups and is therefore reactive. This silicone fluid is fully integrated in the resulting polymer network during curing.
As the silicone fluid becomes part of the network, it cannot migrate out of the cured products of the pigmented silicone rubber. The pigment paste does not influence either the mechanical and thermal properties of the cured rubber products nor the adhesive properties of self-adhesive formulated silicones. Cured rubber products pigmented with ELASTOSIL® Color Paste FL UV Fluorescent only differ from non-pigmented cured products in their UV fluorescence. This makes the pigment paste a suitable UV marker for liquid silicone rubbers and other addition-curing silicone rubber compounds.
Processing is simple. When a liquid silicone rubber is injection molded, the pigment paste is added to the mixer via an additional color line in the injection-molding machine. For pourable, addition-curing silicone rubbers, it is stirred into the rubber mixture. The UV-fluorescent pigment paste can be mixed with any other pigment paste in the ELASTOSIL® Color Paste FL product range.
WACKER’s new pigment paste addresses a key trend in the silicone industry. In view of the increasing requirements for flawlessness of the supplied products, more and more silicone processors are striving to develop automated quality control including complete testing of the entire range of produced silicone molded parts or silicone coatings. This kind of 100-percent testing, particularly for large-scale production, previously entailed considerable personnel costs.
The new pigment paste ELASTOSIL® Color Paste FL UV Fluorescent now provides a cost-effective alternative. It makes it possible to provide the cured rubber products with a fluorescent mark, paving the way for computer-controlled visual testing. The UV pigment paste can help, for example, computer-aided camera systems to determine, fully automatically, whether the injection-molded silicone component is exactly in the intended locations. The same applies to silicone-coated textiles: optical test systems can be fully automated to test whether the coating is bubble-free and entirely covers the textile web. It renders manual visual inspections unnecessary.