I didn't write this - i found it online from SDMag:
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.
