WHAT DO I NEED TO KNOW ABOUT INK?

WHAT DO I NEED
TO KNOW ABOUT INK?

Most new large format flatbed and hybrid printers use UV curable ink. The print process is cleaner and faster than the solvent-based print process which was previously used for large format printing.

Because existing users may be considering a move from solvent to either latex or UV curable technology, we will explore all three ink technologies.

Solvent inks

Solvent inks comprise coloured pigments suspended in a petroleum-based solvent. Print is delivered wet and the solvents are dried or ‘gassed off’ using heaters. The evaporation process releases volatile organic compounds (VOCs) that can be harmful to the environment and which require venting.

Solvent inks produce vibrant colour images that are waterproof, fade resistant and flexible (elastic). Because the ink is flexible and adheres well to vinyl and film, solvent inks are (or were) commonly used to produce large format graphics for outdoor display.

Solvent inks can appear to cost less to buy than UV curable inks. Solvent inks typically have a lower cost per volume as purchased but, because the solvents evaporate during the gassing off process, a greater volume of ink is required to provide the same coverage.

Advantages

Low perceived ink cost (by volume)

Disadvantages

Wet ink is easily smudged
Curing process increases lead time
Noxious and potentially harmful fumes
Industrial ventilation is required
High energy costs (dryers and ventilation system)
Additional space is required (for dryers and work in progress)
Special range of substrates required

Latex Inks

Latex inks are used in roll to roll devices just like solvent printers but work in a different way.

Latex ink contains specific type of polymers which surround and suspend the ink pigments in water. This liquid is jetted onto the media through print heads to form the image. Heat is used in two ways. It first evaporates the water away leaving the polymer pigment behind. The heat then is used to activate the polymers to bind the pigments to the media. The prints come out dry and can be used straight away improving productivity.

Unlike solvent inks, the latex ink has low-VOC emissions. No special ventilation is required for operating the printer. Low odour Latex inks make it ideal for high quality indoor signage, wallpaper etc., and very durable outdoor uses such as vehicle wraps.

Advantages

Low smell and VOC emissions
No drying time, straight to secondary processing
No ventilation required
Wide range of media
Faster print speeds
Can be used in sensitive environments where odour has to be low

Disadvantages

Requires a lot of heat to fix and dry prints
Energy consumption
Prints can be subject to scratching if mishandled

“The variety and volume of work the printer can get through and the speed in which it prints allows us to take on many projects at one time without having to compromise on the quality of the end product. The Ricoh printer has allowed us to take on van wrapping projects as the latex ink, combined with the media and laminate, creates a high-quality solution that is quicker and easier to apply than graphics created on solvent ink and UV printers,”

Declan McNeil, Director, Cora Graphics

UV curable inks

UV curable inks comprise coloured pigments and a photo initiator suspended in an acrylic polymer (plastic) emulsion. Instead of heat, the ink is cured by exposing it to ultra violet (UV) light. Exposure to UV light causes the photo initiator to react with the acrylic polymer, instantly hardening it and fixing it to the print media.

Like solvent inks, UV curable inks produce vibrant colour images that are waterproof, fade resistant and flexible (elastic).

Since no secondary finishing processes, such as such as mounting or laminating are necessary, printing directly onto rigid substrates using UV ink, reduces cost and increases productivity. And, because the print media is not subjected to heat, more delicate media can be used, including plastic carrier bags and even laptops.

The UV curing process offers numerous advantages. The ink cures instantly, increasing throughput speed, reducing job turnaround times and increasing production capacity. No dryers are required, saving space and reducing energy consumption. And, because the ink does not evaporate, less ink is used and venting isn’t usually required.

Advantages

Wider range of substrates
Shorter lead times (ink dry on delivery)
More productive (faster throughput)
Energy and space savings (no ventilation or dyers)
Easier to maintain (UV inks do not evaporate and are less prone to clogging)

Disadvantages

Higher initial cost of acquisition