UV-reactive inks and coatings require a high-intensity UV light source to initiate a chemical reaction that cures the ink or coating almost instantaneously. The UV wavelengths best suited for curing inks are between 200 and 400 nanometers.
CRCBOND UV ink
There are several lamps suitable for producing these wavelengths, mainly high pressure mercury arc lamps, electrodeless lamps and medium pressure mercury arc lamps.
High pressure mercury arc lamps are typically constructed as capillary-type tubes and require a water jacket to maintain the correct operating temperature. These lamps are limited to short lengths and the lamp life is usually less than 1000 hours.
Electrodeless mercury arc lamps have no electrodes. The arc is created by generating microwaves. slip additives for coatings These types of lamps are usually produced in two standard lengths, 6 inches and 10 inches.
The most widely used are medium pressure mercury arc lamps. This can be air or water cooled and can be manufactured in various lengths.
The lamp body is made of transparent vitreous silicone tubes of different diameters and wall thicknesses. This material, known as quartz, has important properties that are critical to the efficient operation of UV systems. It is 90% transparent to UV light, while ordinary glass filters out all but the longer, weaker wavelengths. The surface temperature of the UV lamp under normal operating conditions is between 600°C and 800°C. Quartz can withstand these temperatures because of its very low thermal expansion properties and high melting temperature.
The electrodes that hold the high-voltage arc are made of tungsten rods made of tungsten wire. Tungsten must be able to withstand internal arc temperatures in excess of 3000°C. Electrodes must be carefully designed to ensure efficient, reliable operation and long lamp life. The parameters affecting this design are very complex.
Due to the extremely high operating temperature and the low expansion properties of quartz, it is very important to select the proper material to connect the electrodes inside the case to the power source outside the case. Use high temperature wire for additional electrical connections. Electrical insulation of the lamp ends can be achieved through the use of ceramic end caps.
Like ordinary household light bulbs, medium pressure mercury arc lamps generally do not fail suddenly. Efficiency declines relatively slowly until insufficient UV light is emitted for the lamp to cure effectively. This drop is mainly due to the decreased UV transparency of the quartz sheath and depends on many factors: bulb cooling efficiency, power rating, electrode current rating, electrode cooling efficiency, contamination on the outer surface of the bulb (dust, etc.) and switching frequency.
When used correctly, CRCBOND UV curing lamps ensure a high level of curing efficiency for at least 1000 hours, and with proper handling, they are still capable of delivering at least 80% of the original output.
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