Inks & Toner

Inks and toner contain wax additives to impart specific properties such as coefficient of friction (impacting slip resistance), dispersion and resistance to water, solvents or grease. IGI produces natural and synthetic waxes for the ink and toner industry.

Printing is defined as the reproduction of images to a substrate. To create an image there must be differentiation between the image area (ink on) and non image area (ink off). Main printing processes accomplish this either by raising the image (flexo and letterpress), differentiating chemically (lithography),recessing the image (gravure), stencil, (Screen print) electronically, (toners).

Printing inks are broadly classified into two main categories; paste and liquid. It can be formulated using chemistries based on oil solvent, water or energy curable.

Raw materials used in inks can be classified into three classifications

1. Vehicles
Vehicles carry pigment to substrateduring the printing process. Vehicles are sometimes refferred to as varnishes. Usually fluid in nature, they consist of resins binders plasticizerand solvents. Can be free flow gelled or viscous

2. Colorants
Pigments or dyes that provide the colour – Pigments are insoluble and need to be dispersed whereas dyes are dissolved in the vehicle. Pigments are more common.

3. Additives
Materials or compounds that contol or modify specific properties. Often added in small amounts additives can impact a wide range of chemical properties including rubrestance, drying, film formation, viscosity etc.

While it is theoretically possible to make ink without additives most modern inks contain multiple additives. Some additives are specific to certain ink types while others such as waxes are used in a wide variety of inks. Additives may be added in the vehicle during processing while others are added during the ink mixing stage.

The Role of Waxes

Almost all inks except inks that will be coated or laminated contain waxes of some type. Waxes provide physical attributes such as rub/scuff resistance, water/solvent or grease resistance and more. Wax can also influence the coefficient of friction to control slip resistance.

In the ink industry both natural and synthetic waxes are used. Waxes are supplied as micronized stir-in powders, votated oil/varnish compounds, oil dispersion for sheet fed and heat set inks, water dispersion, water based flexo/gravure. Typically waxes are used at less than 5% w/w however certain emuslions /dispersion additives can contain a much higher percentage of wax.

For stir-in powders, particle size is an important property (4-6 microns is typical for sheet fed and high speed heat set). Flexo/gravure can tolerate much higher particle size (6-20 microns).