General Information

Ultraviolet curing is a photochemical process in which an abundant amount of UV energy is produced by a mercury discharge lamp and focused at monomers through cross linking or polymerization.  The sensitizer present in the monomer absorbs UV radiation at a rapid rate and initials the reaction in the monomer, producing a hard and dry surface.  The rate or speed of the curing process depends on the following:

(A) Chemical Compound - Each monomer will cure at a different rate, depending upon the composition and the amounts of sensitizer, pigment and the chemical additives.

(B) Thickness of Coating - The thickness of a specific coating is not directly proportional to exposure time.   The amount of UV energy inside a layer of coating decreases exponentially with depth.  If 70% if the UV energy is absorbed in the top .001" if coating, then 70% of the remainder or 7% of the initial amount will be absorbed into the second .001" if coating.  Thus, a two fold increase in thickness requires a ten fold increase in UV intensity.

(C) Amount of UV per Unit Surface - Normally, the curing speed will increase with the amount of UV energy per unit surface at a non-linear rate.  If a 200 watt per inch mercury lamp was increased to 400 watt, the curing speed could increase ten fold.  In addition, special Superior metal halide lamps can trigger the receptor at an even faster rate with a standard 200 watt per inch lamp.  The charts in Figure 1 dictate the flexible control that Superior technology has developed over the years.  We can pinpoint the UV energy produced by our curing lamps to your exact specifications.

The sensitizer should absorb UV in the range which is not absorbed by the monomer or pigment. The wavelength produced by a Superior medium pressure mercury lamp or Superior metal halide lamp should coincide with the wavelength absorbed by the sensitizer. The continuous light spectrum produced by these lamps in the 200 to 440 nanometer range propels technology to a plateau of efficiency.

Radiation emitted from our mercury lamp depends on many factors.  In a gas discharge lamp, the output is a function of the atomic structure of the gas molecules, their temperature, pressure of the gas vapor, and quality of materials used in the basic construction.  Superior lamps utilize only the finest raw materials available.  Second best will not do.

If your application requires the absence of ozone gases, which is a by-product of an ultraviolet producing lamp, our engineering department can effectively respond with a special grade of quartz that prevents the 254 nanometer line from reaching oxygen in the atmosphere.  Please bear in mind that all effective lines below 254 nanometers are blocked which might be required to start your reaction.  Figure 2 shows the basic area of interest for industrial curing.

(D) The UV Spectrum - Once the basic concept of radiation has been understood, how ultraviolet radiation fits into the scheme of things, and what UV Curing contains, then, one can easily understand the advantages and disadvantages of various light sources.  Standard Superior curing lamps display the following characteristic in Figure 3.

The far ultraviolet lies between 200mn and 300mn and is classified as Germicidal or UV-C.  The middle ultraviolet lies between 280nm and 320nm is called Erythema (suntan) or UV-B.  The near ultraviolet lies between 320nm and 400nm and is commonly called Black Light (long ultraviolet) or UV-A.

The Superior medium pressure lamp builds vapor pressure as the power and temperature start to increase.  As shown below in Figure 4, as the power input increases, so does the efficiency (ratio of total radiation to power input.  From 100 watt per inch to 300 watt per inch the efficiency is increased by 12%)

This efficiency further evolves from the highly skilled technicians that receive years of critical training and their adaptability to construct flawless linear lamps. Our Superior 400 watt per inch lamp will more than double the cure rate when compared to two lamps running at 200 watt per inch each.

The spectral output does not shift as the lamp power is increased from 100 to 200 to 300 watts per inch. There are a multitude of medium pressure mercury lamps varying in shape, size, diameter, length and power output. Please note that a Superior lamp operating on a properly designed stabilized ballast has a power conversion from line input to lamp output of 92%. The biggest advantages of the Superior line of curing lamps are low cost, an inventory stocked with various standard lengths of 1.5 inches to 180 inches, and the reputation that goes with the name.

(E) Advantages - The Superior line of UV curing is paramount to conventional heat curing in many areas.

(1.) A drastic reduction in "air pollution" becomes possible with the monomer system of excitation. No solvent need be evaporated and expelled into the atmosphere

(2.) The fast and rapid curing rate of Superior standard lamps is known worldwide. Add the correct mix of exotic materials at the same power level and the future starts to unfold. Remember. the efficiency exceeds 90%, and that means saved dollars every second of a work day.

(3.) Huge savings in plant space, labor costs, and the highest quality in improved appearance cannot be overlooked.