Pigments as Raw Materials for Printing Ink Formulations

Date : 10-01-2019

The raw materials for ink production are pigments, binders, solvents and additives.

Pigments- colour the ink and make it opaque

Resins- bind the ink together into a film and bind it to the surface

Solvents- make the ink flow so that it can be transferred to the printing surface

Additives- alter the physical properties of the ink to suit different situations

Pigments as Raw Material of Printing Inks:

Pigments are considered to be the chief constituent of ink and contribute about 50 per cent of its cost. A pigment is essentially any particulate solid - coloured, black, white or fluorescent - that alters the appearance of an object by the selective absorption and/or scattering of light. It occurs as a colloidal suspension in ink and retains a crystal or particulate structure throughout the colouring or printing process. Colour Index System number is generally used to identify the organic pigments in modern inks. It reflects the colour shade or hue, and structural and chronological details (order of synthesis) of the pigment. For example, the well-known blue pigment Copper Phthalocyanine Blue is known by Colour Index No. 74160. As the particle size reduces, the colour intensity (strength) of a pigment increases and the opacity peaks around a particle size of 0.3Âµm. The molecular structures of three important pigments used in ink are shown in image.

Pigments colour the ink and provide gloss, abrasiveness and resistance to light, heat, solvents, etc. Special pigments such as extenders and opacifiers are also used. Extenders are transparent pigments that make the colours of other pigments appear less intense, and opacifiers are white pigments, which make the paint opaque so that the surface below the paint cannot be seen.