Consumables
HP Technology At-A-Glance
Thursday 06. August 2009 - HP Latex Ink Technology
HP Latex Inks are pigmented, water-based inks designed for commercial and industrial printing applications, including event banners, transit signage, and other outdoor applications as well as high-quality indoor signage. These inks use HP’s innovative aqueous-dispersed polymer (“Latex”) technology to provide high print durability and display permanence and their water-based formulation reduces the impact of printing on the environment and enables an improved printing environment for print shop employees.
HP Latex Inks were developed with HP Thermal Inkjet printheads in six-color writing systems that provide high quality at high productivity without requiring daily manual maintenance or service calls for printhead replacement with three user-replaceable HP 786 Designjet Printheads in HP Wide Scan Printing Technology for an 8.5-inch (216-mm) print swath.
Ink Composition
HP Latex Inks consist of a liquid ink vehicle that carries latex polymer and pigment particles to the surface of the print media. Physical and chemical properties of the ink vehicle are critical both for drop ejection performance and control of ink-media interactions. These properties are obtained by formulating the ink vehicle with a combination of water (up to 66%), co-solvents for aqueous inks (less than 30%), and additives. Co-solvents are water-soluble organic liquids.
High water content gives HP Latex Inks the high surface tension and low viscosity that are ideal for use in HP Thermal Inkjet printheads, but water alone is not a practical ink vehicle for printing on the wide variety of media used in commercial and industrial applications. Co-solvents and additives play an important role in consistent drop ejection and ink-media interactions. They lower surface tension to wet the internal surfaces of the drop generators, keep the surface of the thermal inkjet heater resistor and orifice plate clean, minimize viscous plugs in the nozzles, and affect how the ink droplet wets the surface of the print media. Co-solvents soften uncoated vinyl for better adhesion and evaporate in the printer to produce a completely dry print.
A key innovation in HP Latex Inks is the incorporation of latex polymer particles. “Latex” is a term that describes a stable, aqueous dispersion of microscopic polymer particles. It is important not to confuse the polymers used in HP Latex Inks with those found in natural materials, such as latex rubber.
Inside the HP Designjet L65500 Printer, a liquid film of HP Latex Ink on the print media is exposed to radiant heaters and airflow in the Print Zone and Curing Zone. This process evaporates the ink vehicle and causes the latex polymer particles to coalesce, forming a continuous polymer layer that adheres to print media and encapsulates the pigment to form a durable colorant film.