Inkjet Systems

Written February 8, 2019

Categories: Digital

Aqueous or Water-based Inks

Characteristics:
  • Primarily derived from water, 70 to 90 percent, with a small amount of a milder solvent so that the ink will adhere to the medium. Can be dye based or pigment based. Dye are more vibrant than pigments, but the color will generally fade faster than pigments.
  • Mostly used for retail POP for short-term outdoor prints, long-lasting indoor prints and indoor backlit materials.
  • Have a relatively clean handling process.
Considerations:
  • Typically must go through a laminate finishing process in order to protect them for extended indoor and outdoor use.
  • Using aqueous inks requires a coated print media for acceptable imaging.

Mild Solvent Inks

Characteristics:
  • Often dubbed “mild,” “low-odor” and “eco-solvents” because they do not have the ingredients or aggressiveness that true solvent inks have.
  • Tend to have a low odor during production.
Considerations:
  • May emit hazardous compounds in the air, even if they are not classified as having VOC content. The variety in state regulations means these inks could be classified as having VOC content in one state but not in another. It’s important to check with state regulations to see if any appropriate measures need to be incorporated.
  • The “eco” in eco-solvent originally referred to its economical price rather than the ink being ecological or environmentally friendly, which the ink may or may not be. These inks generally contain glycol esters or glycol ether esters, which are both derived from mineral oil.
  • Printers should keep in mind that less odor does not necessarily mean fewer chemicals are released during production. Read the manufacturers MSDS sheets.

Solvent Inks

Characteristics:
  • Commonly regarded as the most economical inks for digital printing today, in terms of equipment costs and maintenance expenses.
  • Produce highly durable outdoor prints.
  • Media is less costly than coated media for aqueous inks.
  • Well suited to printing on soft and compatible flexible materials. They can be used on low-cost, uncoated materials, such as self-adhesive vinyl, fabrics and scrim banner materials.
Considerations:
  • Dry quickly but emit volatile organic compounds. VOCs are a hot-button issue in environmental regulations and worker safety debates. For printers that are producing a larger volume of prints with conventional solvent inks (or using wide-formant digital printers), an appropriate ventilation system may be needed to safely and effectively manage VOCs and properly mitigate them.
  • Solvent prints need to "outgas" 12-24 hours before laminating. Outgas is the release of organic solvent vapors that continues for some time after printing has concluded.
  • Increased VOC emission legislation in North America and Europe could impact the use of these inks in the international marketplace.

UV-Curable Inks

Characteristics:
  • More versatile in terms of what they can be printed on, rigid substrates, such as board product, plastic, glass, wood, ceramics and metal.
  • Can help achieve fast production because there is no wait time for prints to dry.
  • Save on production costs and media versatility despite having up front equipment costs that are higher than other digital printers.
  • Avoid continual cleaning and purging of the print head to remove insoluble products.
Considerations:
  • Tend to be more expensive than other inks. Part of the expense comes from the higher cost for the ink’s raw materials.
  • UV ink handling and cleaning requires gloves, people can become sensitized to UV ink.
  • Requires UV lamps on the print heads for the purpose of ink curing. The UV lamps must be changed out periodically.
  • UV-cured prints may require finishing for highest durability.
  • High energy consumption for mercury vapor UV lamps used in some UV printers.
  • The use of hard lamination is not possible due to the height of the hardened UV ink.

Latex Ink

Characteristics:
  • Hp specific ink used in the HPLatex printer models.
  • Latex is a term used to describe a water-based dispersion of very small latex polymer particles.
  • The in-printer curing process (heaters) evaporates the water-based ink components and causes the latex particles to coalesce into a durable film that encapsulates the pigments and bonds to the print media.
  • Prints have high stretch performance and conformability.
Considerations:
  • Only currently available for the HP line of latex printers.
  • Substrates are heated for printing and high heat is used for curing/drying.
  • Energy costs of drying system.
  • Media stretching may occur.