The Inkjet Ink Market

Ink evolution: Inkjet inks for signage applications commonly use a water, solvent, or monomer base, and when mixed with various proprietary ingredients offer optimum performance for use in specific types of inkjet printers.

• Both dyes and pigments are used in inkjet inks for colorants.

• Dye-based colorants are more common in water-based inks used in desktop and wide-format photographic inkjet printers; pigments are more common in solvent inks used in large format printers.

• Inkjet Ink Types:

• Solvent (true solvent)

• Mild solvent (eco-solvent)

• UV-curable

• Latex / Resin

• Traditional Water-based

• Inks must be compatible with the substrate.

• Vinyl substrates dominate solvent inkjet printing for outdoor signage applications.

• Inkjet printers are designed to run with specific ink types and are not interchangeable.

• Solvent ink is the backbone of the digital inkjet printing industry for outdoor signage applications.

• Active solvents allow binders in the ink to bond to the polymeric vinyl structure when the solvent is evaporated.

• Solvent ink is the standard for vehicle wraps, banners and signs, and many outdoor applications.

• Solvent printers can successfully print onto a wider variety of uncoated (less expensive) substrates than mild solvent printers.

• Solvent inks emit volatile organic compounds (VOCs) that must be ventilated or otherwise removed from the workplace environment.

• "Bio solvent" inks contain solvents and binders made from renewable crops, such as corn (not petroleum-based).

• EFI BioVu (Vutek)

• MUBIO (Mutoh)

• Ethyl lactate is the main solvent

• Biodegradable

• Low flash point

• May be shipped and stored without the precautions required of strong solvent inks.

• Not very toxic to humans

• Reduced need for ventilation systems 

• May be some compromises in performance

• Pigments may or may not be “green”

• Mild solvent inks emit a less intense odor than true solvents, and also tend to emit fewer toxic VOCs than true solvent inks.

• Mild solvent inks combine the durability advantages of true solvent ink with the environmental advantages of water-based ink.

• Color quality and durability have improved.

• Cost has dropped significantly.

• Mild solvent printers are typically found in relatively small sign shops.

• Typically provide 2-4 year outdoor durability with lamination

• UV-curable inks (monomer-based) are a viable solution in many signage applications.

• Liquid monomers in the ink become solid polymers when the inks are exposed to high levels ultra violet (UV) energy emitted by the UV-curing lamps built into UV-curing printers.

• Presents an alternative to VOC hazards

• But current ingredients (in their liquid form) still pose contact and respiratory hazards

• Today’s inks offer better adhesion and are safer, more versatile and dry faster

• Provide a high gloss finish

• More efficient photo initiators accelerate and ensure complete curing

• Free-Radical UV inks

• Most widely used in wide-format digital inkjet printers.

• Technology works well on most common substrates.

• Free Radical Ink — Cons

• Sensitive to oxygen, which suppresses the curing reaction; must cure quickly, which requires greater UV intensity, more photo initiator (to allow for oxygen quenching) or slower printing speed.

• More intense UV light causes more heat on the substrate, and some substrates can’t tolerate the heat.

• More photo initiator adds to cost and can cause an objectionable odor.

• Cationic Inks (used in Gerber Scientific’s Solara ion series).

• Can be fully cured after the initial UV exposure (dark cure)

• Not sensitive to oxygen and requires less UV energy to initiate curing.

• Purported to provide better adhesion, higher gloss, better opacity, better flexibility, better hardness, better chemical resistance and lower odor than free radical inks.

• Cationic Ink — Cons

• Cures more slowly than free radical ink

• Sensitive to moisture, acids and bases

• May require substrate pre-heating

• Ingredients are more costly

• Many solvent and UV-curable types of ink contain ingredients that pose health and environmental hazards and therefore, require special handling protocols.

• VOCs in solvent-based inks

• Reactive ingredients in uncured UV inks

• Exposure to intense UV energy from cure lamps can  also be harmful. 

• New latex and resin water-based inks offer an alternative to solvent and UV-curable inks.

• HP's water-based latex inks

• Sepiax water-based resin inks

• Attempt to replace solvents and reactive ingredients with less hazardous materials and water.

• Offers comparable durability on numerous substrates, including uncoated vinyl.

• Challenges of latex/resin type water-based inks

• Evaporation rate is much slower compared with organic solvents in solvent inks, thus more heat is required to dispel water

• Coalescence / puddling is a potential problem

• Requires slower printing speeds and precise system calibration and temperature control.

• Traditional water-based inks are widely used for photographic printing and short-term indoor signage applications.

• Water-based inks can use either dye or pigments for colorants

• Inexpensive compared to other types of inks

• Pose little or no health risks

• Offer wider color gamuts than other inks

• Traditional water-based inks — Cons

• Traditional water-based inks, unless fully encapsulated, are not appropriate for outdoor signage applications.

• Dye-based colorants in water-based inks tend to fade relatively rapidly

• Traditional water-based inks do not adhere to many substrates unless they have been coated with an emulsion designed to accept water-based inks.

• Bulk-ink systems are available for some, but not all inkjet printers.