Inks are used generally for a variety of industries especially pharmaceuticals and food. They have their application in bar coding, batch numbering, expiry date marking and other identification purposes. The Formulation varies extensively according to the method of application and end use. Ink manufacturing process requires various processes, formulation, equipments and manufacturing steps known as “Recipes” for its production. A wide range of materials are required for the formulation of good quality ink, namely- resins, polymers plasticizers, dyes, conductive salts and premicronized pigments. These ingredients are required to be added in various forms like powdered, liquid or chip forms. The powdered and liquid forms are to be predispersed in aqueous or organic solvent. Manufacturing of different types of Inks (Conventional offset Ink, UV Ink, FLexo/ Gravure Inks) generally follows the same Principle. The most important steps in ink formulation is dispersing of the pigment in the vehicle, so that the colorant can be transported by it to the substrate. There are two main technologies in used in the manufacturing of Inks: continuous (CIJ) and drop-on-demand (DOD).
The manufacturing process includes the following steps:
A vigorous in-tank movement is to be provided by the mixer to properly mix the light powders thereby preventing the dense solids from sinking to the bottom of the vessel.
Premicronized pigments are used to prevent further particle size reduction so as to meet the requirements of de-agglomeration. The particle size greatly affects the strength of colour, since the smaller particle size has the higher surface area and thus the stronger the color
Conventional agitators cannot solve the problem of proper mixing of the ingredients. Insufficient level of dispersion may lead to an unsatisfied product quality which may result in printing failures. Agglomeration of the ingredients when added to base liquid may also be unsolvable by conventional agitators. Improper mixing of the ingredients can result in longer mixing time.
These drawbacks and difficulties can be easily rescued from by the usage of Wahal Engineer’s High Shear mixer. The ink produced by this process has an acceptable range of dispersion.
The manufacturing process is as follows:
Step 1: in the first stage all the ingredients are properly charged. A severe suction force is applied to create a centrifugal force which draws the ingredients upwards into the workhead.
Step 2: this centrifugal force in turns moves the particles to the fringe of the workhead. The solid particles are disintegrated leading to a agglomeration free solution. This is obtained by the milling action of the stator and the rotor. The materials are then further projected at a great velocity back to the mix.
Step 3: the process continues with fresh materials being incessantly drawn, passing through the work heads and continuing the process of size reduction thereby accelerating the mixing process.
The advantages of the process is that there is a
- Remarkable Reduction in the processing time.
- Rapid mixing of the ingredients.
- Agglomerate free solution, which is the result of the high shear force
- VOC emission is also reduced as a result of shorter processing time.