PRINTING INK

Ink is essentially a mixture of powders (pigments, calcium carbonates, etc.), varnishes, oils, dryers, anti skinning compounds and other chemical ingredients. The printing are classified in different groups, namely :

a) Letter press ink - Letter press ink is being used on slow machines, where the paper is generally fed manually. These are usually based upon Mellic Resin, prepared from stand oil, spindle oil, B. Oil, alkali Refined linseed oil etc. The ratio of these oils differ from ink to ink and is dependent upon many other factors like paper in use, climatic conditions and speed of impressions. Apart from the pigment, resin, varnish, fillers, wetting agents, dryers and antiskinning compounds are used.

b) Web offset inks- The web offset inks are water repellent, quick drying type and of high tag. and are suitable for very high speed automatic machines. The quality of inks are of such type that it not only dry very fast, but could be transferred to paper by the plate easily, under normal pressure. Web offset inks are mainly based on Phenolic resins, prepared with Mobil Oil, Spindle oil, stand oil and ARLO. Bitumen of Grade 15/15. The ratio of these oils are based upon the quality of ink and depends upon the type and grade of machine, paper and climatic conditions. Anti-skinning compounds and dryers etc. are added in different proportions depending upon the service.

c) Tinplate printing ink - The inks produced for tinplate should have high adhesion properties so that, after baking, these inks are not scratchable even under severe conditions of deep drawing and formings. Tinplate Printing Inks are based upon Mellic Resins and alkyed synthetic resins of Dehydrated Caster oil base. These are generally prepared with ARLO (Alkali Refined Linseed Oil) Dehydrated Caster Oil and toners. Other additives wetting agents Anti-skinning compounds and dryers are used as per requirements.
PROCESS.


In manufacturing ink, varnish plays the most important role in composition of inks. The manufacturing process are divided in to following steps :

1. Weighing of ingredients.
2. Manufacture of varnish - Varnishes are prepared by mixing and heating resin (Mellic or Phenolic) and oil at appropriate temperature for specific period of time in an enclosed vessel till they dissolve completely and then cooled.
3. Mixing of powders, varnishes and other chemicals in the planetary mixer.
4. Dispersion and homogenising in Triple Roll Mill
5. Testing of Product to check the viscosity of the product and the tag required.
6. Filling and Packing
7. Keeping records by Kardex system.