Ultraviolet curing (UV) inks are not brand-new to the marketplace, however they have continued to build momentum as the ink of choice for increasingly more screen printing applications. UV inks are not the answer to whatever. From environmental benefits to faster production speeds, more and more evidence is being collected that recommends that UV is the best choice for many, if not most, situations in today’s screen printing environment.
Before UV inks and UV treating systems (dryers) ended up being a viable option for multi-colored screen printing, heated conveyor dryers were the only option to dry each color prior to the next one was used. In order to run an automated screen printing line with several colors, multiples of machine/dryer mixes (often as big as thirty feet long for each color) had actually to be linked. Systems running conventional inks have a hard time running faster than 60 prints per minute due to the limits on how quickly the ink can be cured. The faster the device runs, the larger the drying system requires to be. As one can picture, this ended up being an incredibly troublesome and expensive venture for multi-color screen printing units.
Multi-color screen printing kit today utilize ultraviolet lamp systems that offer output in the 300 to 400 watts per inch (WPI) range and spectral output in the defined range needed for optimum curing. Many UV lamps use mercury and ingredients to modify and focus the output. A normal 10 inch light system running at 300 WPI will produce 3000 watts. Special cooling and exhaust systems are required in addition to correct shielding to limit UV direct exposure around the machine.
With this kind of UV curing system, multi-color device lines can be assembled with automated print/cure color modules that are as little as 5 feet long for each color! Automatic lines to use as much as 6 colors are possible, saving the screen printer both floor space and electrical energy. In addition, speeds of over 100 prints per minute are possible due to the fact that of the instantaneous treating time from one color to the next.
UV curing devices usually falls under 2 primary classifications: conveyor systems for use with semi-automatic screen printing devices, and curing systems designed and integrated in conjunction with automatic screen printing devices. Semi-automatic machines can be converted with the usage of brand-new screens and the addition of a UV treating system. Systems are readily available in numerous configurations from flat sheet systems to 3D container printing units that rotate the bottle or container in front of the light. Older, automatic screen printing systems can be retrofitted as well. It is recommended to work with a business that has experience with these types of conversions if one is considering the addition of a UV treating system.
Probably the main concern with UV inks, which should be monitored carefully, is the quantity of ink that is applied to the plastic substrate. UV inks are rather translucent by nature due to the fact that the light energy needs to reach the bottom of the finishing at the substrate surface for correct curing. Without developing a blur problem, moving the squeegee off center can help control the ink deposit or opacity in a UV ink application.
Ink Benefits and Drawbacks
UV inks can supply financial advantages for the screen printer. UV inks are normally more pricey, the operator can lay down a smaller quantity of ink since of the finer mesh used versus standard solvent inks. With UV inks, 100 percent of the ink transferred stays on the plastic part– nothing is flashed off.
As discussed earlier, the best economic advantage that UV inks supply is the increased production speeds that can be recognized. In a lot of cases, UV inks can perform at much higher speeds than traditional inks due to the fact that of the curing time included. Once again, the flooring area cost savings and potential energy savings realized through using UV inks are significant.
UV inks likewise are operator-friendly. On the other hand, UV inks usually do not need any type of additive to boost adhesion or change the characteristics of the ink. Because UV inks should be exposed to UV light to cure, the ink does not dry on the screen.
In addition, ecological benefits exist with UV inks. And due to the fact that solvents can be combustible or flammable, there are lots of guidelines on shipping, storage, and disposal that do not accompany UV ink products.
Lastly, UV inks offer a glossier cosmetic surface on the plastic substrate. And since a finer mesh is utilized, more comprehensive, finer copy can be screen printed.
Making use of UV inks presents many benefits, it is not the answer for all applications. In addition, there are some plastic substrates that do not accept UV inks at all. There have actually been difficulties with using UV inks with unique processes such as elongation for in-mold designing and vacuum forming applications.