Textile printingTextile printing is the process of applying colour to fabric in definite patterns or designs (or) Applying coloured patterns and designs to decorate a finished fabric is called 'Printing'. In properly printed fabrics the colour is bonded with the fiber, so as to resist washing and friction.

Textile printing is related to dyeing but, whereas in dyeing proper the whole fabric is uniformly covered with one colour. In printing one or more colours are applied to it in certain parts only, and in sharply defined pattern

Printing can be called as a localized dyeing colourants used in printing contain dyes thickened to prevent the colour from spreading by capillary attraction beyond the limits of the pattern or design.

BASIC TECHNOLOGICAL PRICIPALS OF TEXTILE PRINTINGThis involves different techniques and different machinery with respect to dyeingSteps:

Colour paste preparation Printing Drying Fixation After – treatment

Preparation of printing pastes

Dyeing Printing

Mono colour application Mono or multi colour application

Dyes are applied liquid form Dyes are applied paste form

Salt is added for better exhaustion Not needed

Temperature is needed- penetration Not used during printing but applied after printing ( dry and fix the dye)

Water plays important role Thickening agents plays here

Time is required Not need

Half and full bleached fabric is used full bleached fabric only used

Cost is low Higher

Wet or dry condition for fabric Only dry condition

Consumes more time Short time

Consume more water Less water

Open width or rope form Only open width

Uniform colour applied on both side Face is darker and another face paler

Type of specific formulation used depends on the fiber, the colorant system used and, to some extent, the

type of printing machine.

Typical ingredients used

• Dyes or pigments

• Wetting agents

• Thickeners

• Binders, cross-linking agents

• Sequestrants

• Dispersing agents - surfactants

• Water-retaining agents (humectants)

• Adhesion promoters and miscellaneous agents

• Defoamers

• Catalysts and mild oxygen carriers

• Oxidizing and reducing agents, carriers and swelling agents

Dyes or pigments:

The dyes or pigments are selected depending on type of fibre, style, and the effect required.

Wetting agents:

To facilitate the wetting of dyestuff and subsequently to dissolve it.

Ex: Turkey Red Oil (TRO), Sodium salts of sulphated vegetable and animal oils ,etc..

Solvents, solution acids, dispersing agents :

To prevent aggregation. -- Ex: Acetin, Diethylene gycol, Polyethylene glycol and glycerin A

Humectants or hygroscopic agents:

They absorb sufficient amount of water during steaming and enable the dye molecules to diffuse into the fibre.

Ex: Urea and Glycerin

Thickeners:

These are used in printing in the form a paste or emulsion in order to prevent spreading of the dye and hold the dye

particles in the printed portion until they are fixed into the fibre

Ex: Natural- Starch, Gum tragacanth, Locust beam gum, Sodium alginate

Modified: CMC, British gum, Gum indalca

Synthetic: Acrylic polymers, Emulsion thickeners

Defoaming agents:

To curtail the foam generation while preparing print paste

Ex: Silicon, Pine oil derivatives, Perminal KB

Oxidising agents and Reducing agents :

OA - For developing the final colour during steaming

Ex: sodium nitrite and resist salts

RA - Rongolite C and stannous chlorite

Carriers and swelling agents:

These can be helpful in fixing the prints