Sign & Digital Graphics

June '17

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S I G N & D I G I T A L G R A P H I C S • June 2017 • 61 Latex or UV LED? "Latex" ink is the name coined by Hewlett Packard for their water-based ink that incorporates a polymer binder to bond the pigments to the substrate. For vinyl applications, no coating is required. This system can effectively print directly onto a range of uncoated vinyl using heat to dry the ink so that it does not run and a binder to provide a film when dried. The objective is to provide a durable image on uncoated vinyl without the sol- vents in eco-solvent ink. Like aqueous inks Latex inks provide a very "green" solution without the production of unde- sirable VOCs and solvent vapors. Still, for many other substrates a treatment or coating is suggested to provide an optimum solution. There are a range of substrates available that have been opti- mized for Latex printers. Although available at a higher cost, UV-curable inkjet is also a contender to be considered. The ink includes little or no solvent or water and is cured when exposed to ultra violet light. The entire droplet is cured and becomes solid pro- viding a polymer matrix that incorpo- rates the pigments providing the color. This technology is ideal for certain appli- cations, most popularly for printing onto rigid substrates such as composite alumi- num, corrugated plastics, Dibond, PVC sheeting, foam board, etc. Many of today's UV-curing printers are using an LED-based light source. LED refers to the use of light emitting diodes as the UV light source. LED UV-cure systems evolved as an alternative to the use of much hotter conventional UV cure lamps employing arc lamp technology. LED cure lights are more energy efficient and run much cooler than conventional lights and this allows printing onto more heat-sensitive UV-cure ink technologies are starting to move away from conventional cure-lamps to cooler- running LED-based UV cure systems. (Image courtesy of EFI) Latex inks, such as those used in the HP Latex 370 printer, are growing in popularity. (Image courtesy of HP)

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