About Ultraviolet Curing

Ultraviolet light has dramatically improved the way we print

What is UV Curing?

Ultraviolet curing has been employed in the printing and converting industries for many decades to help improve product performance and printed longevity. It is an ideal replacement for water or solvent based printing and coating because it is cured rather than dried. It offers outstanding color strength, rub resistance, scratch resistance and chemical resistance.

UV curing involves the use of high-powered medium-pressure mercury vapor UV lamps that emit intense ultraviolet energy in the UVA, UVB, UVC and UVV spectral ranges. Ultraviolet inks, coatings and varnishes are 100% solid with a specific chemical makeup which typically include; monomers, oligomers and photo initiators. The photo initiators act as a catalyst when exposed to intense ultraviolet energy which in turn forms a permanent chemical bond known as “cross-linking” between the monomers and oligomers. Different photo initiator packages are employed depending on the desired effect of the ink, coating, adhesive or varnish. In all cases, the outstanding characteristics of UV cured products offer converters a finished product that is superior to the water or solvent based alternatives.

Why Use UV Curing?

Prior to the advent of UV cured inks and varnishes, many printers and converters struggled to obtain ink density and performance. Water & solvent based systems require hot air or IR drying equipment to flash off solvents or water to yield a 60% solid ink or coating. Ultraviolet inks & coatings are made up of 100% solid materials which yield a 100% solid ink or coating when properly cured.

It is proven that the use of UV cured inks adhesives and coatings offers superior results including:

  • 100% Solid inks provide higher print quality – vibrant solids and cleaner, sharper dot structures
  • Better end product performance due to outstanding abrasion & chemical resistance
  • Super high gloss, chemically resistant varnishes protect the printed surface better, make the printing “pop” and are much less expensive than film laminates
  • Less down time as UV inks and coatings can remain in the machine overnight or between shift changes (simply cover the pan)
  • Higher profitability in flexo printing as they produce less waste
    ... 100% solid UV inks do not change colors
    ... Excellent print impression is much easier and faster to obtain
  • Improved throughput – higher line speeds from instantaneous curing
  • Environmentally friendly – ultraviolet curing does not produce Volatile Organic Compounds (VOC’s) which are the leading cause of destroying the ozone layer that protects the earth from harmful elements of the sun

How Does A Mercury Arc Lamp Work?

A medium pressure mercury vapor UV lamp consists of a sealed quartz tube that contains a small amount of mercury, a specific gas and an electrode with wire leads at both ends of the lamp. When high electrical current is applied to each electrode, the gas inside the quartz tube heats up and vaporizes the mercury in to a plasma state to form an electrical arc. The electrical arc emits very intense UV, visible and infrared energy.

The UV lamp is enclosed in an irradiator which includes a 19-point stepped ellipse high-gloss reflector to capture and redirect UV energy back to the substrate from the back and sides of the UV bulb. The quartz tube will run as hot as 2,500ᵒ F and must remain at a specific temperature so as not to overheat or overcool for optimum UV bulb operation and longevity. Employing a closed-loop, variable-speed exhaust blower with a precisely placed thermocouple wire creates an exact amount of airflow through the irradiator to maintain the target temperature of the UV Lamp.

What Produces UV?

Ultraviolet light is produced naturally by the sun with a fair amount of UVA reaching the earth’s surface. UV light can be produced by a number of sources such as photocopiers & arc-welders. Manufactured light sources can include LED’s, arc lamps and microwave lamps.

What Types of UV Does Lightouch Manufacture?

Lightouch™ UV curing systems are made in the USA in Arlington Heights, Illinois. We manufacture primarily medium pressure mercury vapor lamps at 400 and 600 watts per inch as well as the latest in highly efficient and long lasting Lightouch™ UV LED curing solutions at 16 watts/CM².