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Ink Technology in the Large Format Print Arena

By: Matthew Theobald Click author's name for more of his/her articles

Types of Ink.

There are three main types of ink used in inkjet printers: Solvent, water, and oil based.

Water-based inks: Water-based or Aqueous/thermal inks are divided into two categories, Pigmented Inks and Dye inks.

Dye inks are formulated with the tiny molecules carrying the colour property suspended in a water-based carrier solution. They have a high colour brilliance and a wide gamut of colour. Their light-fastness is not particularly good and they can be prone to fading in adverse conditions. Because the colour is dissolved, it exists at a molecular level and as such it is much more accepting of variations in the quality of the substrate and more importantly the coating on that substrate.

Pigmented Inks.

Particles of pigment are held in suspension in a water-based carrier liquid. These particles of pigment have a vastly greater size that the smaller than microscopic molecules dissolved in solution utilized in dye based inks. They are very resistant to fading and the effects ofwater damage and can even be used outside for a limited time. Because of their heavier structure, they need a more porous or specially coated media in order to dry.

Solvent-based Inks.

Inks in this category can be broken down into 2 groups that are referred to in a number of different ways including: soft, mild, safe, eco, and green as well as hard, real, true, and strong. The term ‘eco’ is often used to suggest that the product is ecologically safe, however they contain chemicals derived from mineral oil which are neither renewable or easily disposed of in a non-damaging way. The agressive solvents are able to produce acceptable results on a wide range of medias - generally at a cheaper cost as the media does not need coating as with the milder solvent inks.

The pigment is held in solution in a carrier together with an adhesive. Once the droplet of ink is sprayed onto the substrate the solvent evaporates leaving the pigment to stick to the surface with resin.

The Solvent inks are delivered onto the substrate using Piezo printhead technology that ensures an accurate and fast print.

Unlike water based inks where the substrate needs to be coated with an ink-receptive layer the solvent process can produce prints suitable for exterior use on non-absorbent, uncoated materials such as self-adhesive vinyl and scrim banner fabrics, pvc and polyester.

Prints produced in this way are far more resilient to fading and scratching.

The Mild Solvent Inks use slow drying carrier fluids and so printers that utilise this type of ink usually have heaters to dry the ink as it is printed.

Agressive solvents dry faster and have the added benefit of softening the substrate surface creating a stronger bond.

Article Source: ABC Article Directory

About The Author: Matt Theobald has worked in the exhibition industry for 21 years, designing, building and producing the graphics for exhibition stands, popup displays and bannerstands. He is co-director of Exhibition Display Solutions Ltd in the Thames Valley. www.exdisplay.co.uk