Tuesday, April 7, 2015

Basic Ingredients of Printing

The Basic Ingredients of Printing

The Basic Ingredients of Printing are as follows:
  • Dyestuffs and Pigments
  • Thickener
  • Acid or alkali or acid liberating agents
  • Carrier or swelling agents
  • Solvents or solution acids or dispersing agents or humectants
  • Antifoaming agents or de-foaming agents
  • Wetting agents
  • Catalyst or oxygen carrier
  • Oxidizing and reducing agents
Printing Ingredients
Dyestuff and Pigments
Dyes or dyestuff may be defined as colorants in which the coloring substance is dissolved in liquid, are absorbed into the material to which they are put in an application for.
Pigments consist of extremely fine particles of ground coloring matter suspended in liquid which forms a paint film that actually bonds to the surface it is applied to.

Thickener is a thick mass which imparts stickiness and plasticity to the print paste so that it may be applied on the fabric surface without bleeding or spreading and be capable of maintaining the design out lines.
Thickener gives the required viscosity to the printing paste; prevent premature reactions between the chemicals contained in the print paste.

Acid and alkalis
Acid: Organic acid
Alkali: Sodium and potassium hydroxide, sodium carbonate, potassium carbonate etc.
These control PH and fix dye on the fabric.

Carriers and swelling agents
These accelerate the rate of dye penetration by fibre polymer, swell the fibre and reduce crystallinity.
Swelling agents: Resorcinol, phenol, polyethylene glycol etc.
Carrier: Diphenyl

Solvents or solution acids or dispersing agents
This prevent aggregation of the dye stuff molecules in the highly concentrated paste of the dye, solution aids increase the solubility of insoluble dyestuff, solvents increase the color value of the prints, assist dye penetration and helps to get bright design. Ex: Diethylene glycol, acetin, urea, gycerine etc.

De-foaming agents
De-foaming agents prevent the formation of foam during printing. E.g. silicone defoamers, sulphated oil etc.

Wetting agents
Substances which reduce the surface tension of water, thereby allowing it to wet a surface easily, which are otherwise non wettable are known as wetting agents or surface active agents, e.g. TRO, olive oil, castor oil etc.

Catalyst or oxygen carrier
These prevent fibre damage, during steaming; accelerate the final color development by oxidation. E.g. Potassium ferrocyanide, copper, sulphide etc.

Oxidizing and reducing agents
Oxidizing agents develop final color in steaming or in the subsequent after treatment, assist in color fixation etc. e.g. sodium chlorate, potassium chlorate, sodium nitrite etc.
Reducing agents destroy color of the fabric. E.g. sodium hydro-sulfite, stanus chloride etc.
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