PREPARATION OF SCREEN

* Nickel screen are used * Screen has 150 pixies per inch. * The Length of screen used is 69 inches and the circumference is 64cm. * The screen is put on coating machine horizontally and Coating of screen with (photo emulsion chemical) agent in dark condition. * After coting Drying at 500c temperature in drying chamber, to fix the chemical. * The polymers most used in the preparation of textile printing screens are mixtures of poly(vinyl alcohol) and poly(vinyl acetate * Then the coated nickel is fixed on machine and program of the design is entered. * Automatically design is drawn on the screen or engraved on screen as well as the exposing of the screen takes place by U.V light. * Hardening of the exposed area are done in light * Washing of unexposed area (design) with cold water and dry it.

http://www.c-s-t.de/content/uploads/CST_DB_DLE-Rotary-Engraver. Figure: 1 CST rotary screen engraver machine

There are two engraving machine. One is inkjet CST (Color scanner technology) and other is wax jet more fine design is printed from wax jet machine.
Expense on one screen is Rs.3000 to 4000.
Screen can be reused.
Figure: 3 Rotary screens
Figure: 3 Rotary screens

SAMPLING DEPARTMENT For sampling, the buyer directly contacts to sampling department. Sampling department then contacts designing department and that's how the sampling department comes into picture. The department prepare the samples, as per the designs specified by the buyers. Designing department design, the proposed design which the buyer demanded by providing the CAD to the company. Screen is used in sampling over baby rotary machine. This particular machine is used for preparing samples. It takes around one hour to prepare one sample along with preparing the paste, which is put inside the screen within the rod that is inserted into it
Firstly sampling is done in 4mt. fabric. Then after fabric is goes under several processes then send to quality checking and different testing. If the sample made is correct or color code given by customer is matched then it passes to printing department and then printing is done in bulk quantity.

PRINTING
Printing can be defined as the localized application of dye or pigment in a thickened form to a substance, to generate a pattern or design.
PRINTING INGREDIENTS:
Dye / Pigments, Thickeners, Binders (for pigment printing), Surface Active agents or Emulsifiers,Reducing agent, Discharging agent / Resist salt, Softener, Antifoaming agents, Hydroscopic agents.

PREPARATION OF PRINTING PASTE:
1) At first we take required amount of dyestuffs in a bath.
2) Then little amount of water is added into the bath for mixing these dyes.
3) Then required amount of urea is added into the dye bath.
4) After then required amount of thickener is added.
5) Then continuous stirring is done for few minutes for mixing all the ingredients.
6) After mixing finally required amount of alkali is added to the dye bath.

MACHINE AVAILABLE FOR PRINTING DEPARTMENT ARE: NAME OF MACHINE | MAKE | COUNTRY OF ORIGIN | USED FOR PROCESS | Rotary Printing 12 color | Zimmer | Austria | printing | Two rotary printing 12 color | Laxmi | India | Printing | Steamer | Arioli | Italy | Print developing | Rotary Screen Engraver | Luescher | Germany | Printing screen developing |

First of all, company get order from buyers in the form of CAD (Computer aided design), where the design that they (buyer) want to be printed on the fabric is mentioned. A sample is prepared and is despatched to the buyer for approval. If it gets approved then the order in bulk is placed. And at this time the printing department, comes into play.
Department, get the greyed fabric from bleaching department, if in case printing is required to be done on the white base. But if the buyer demands printing on dyed base then the fabric is first dyed in dyeing department and then sent to printing department for further processing. There are four types of printing processes in use by the department. The choice of printing process used depends upon either the buyer or else the company themselves decide on seeing the design and taking other parameters into consideration such as penetration and coverage.
Three types of printing processes used are:
a) Pigment
b) Procaine (reactive)
c) Pigment discharge

PIGMENT PRINTING:

Pigment printing is less costly as compared to the other printing processes. Pigments are insoluble, They do not form any kind of bonds with the fiber, Therefore, a binder is require which can bind the pigment to the fiber, There will be no penetration of the pigment into the fiber and the fastness of the final print depends upon the extent to which the resin binds the fibers and the pigments, Therefore could be used for any fibers. A medium is required where the pigments and synthetic resins are incorporated for the printing paste preparation.
In pigment printing pretreatment is necessary such as bleaching for better penetration of color. To remove starch Bleaching is necessary because starch is applied at the time of weaving.
RECIPES
The steps followed in pigment printing are:
PRINTING
PRINTING

CURING AT 150 DEGREE

CURING AT 150 DEGREE

FIXTATION OF COLOR
FIXTATION OF COLOR

WASHING
WASHING

FOLDING

FOLDING

FINISHING
FINISHING

PROCAINE (REACTIVE)

The process of procaine is applied to give the cloth more shine. In this RFD process includes desizing / singeing / mercerization. Fabric is printed on rotary machine by using reactive colours. These colour particles have a tendency to penetrate well in to fibre structure.
Mainly “procaine dyestuffs” are used for printing of cellulosic fibers like cotton and rayon.
The process involved in the printing of procaine is:

PRINTRING
PRINTRING

STEAMING SEMI FIXTATION OF COLOR

STEAMING SEMI FIXTATION OF COLOR

WASHING IS DONE TO REMOVE EXTRA COLOR
WASHING IS DONE TO REMOVE EXTRA COLOR

FINISHING
FINISHING

FOLDING

FOLDING

PIGMENT DISCHARGE:

It is done on dyed based fabric. RFD Fabric is dyed in the darkest base colour then Fabric is printed on rotary machine by using discharging agent (Rangolite). This chemical is mixed with colour dyes. Discharging agent discharges the dyed base colour & then colour dyes fill up the discharged areas.

STEAMING: This process is used to fix-up the printed colour. Controlled steaming procedure will results in better fastness of colour then Washing is done. The process involved in the printing of Pigment discharge colour is:
PRINTING
PRINTING

STEAMING
STEAMING

CURING
CURING

F
WASHING
WASHING

FOLDING

FOLDING

FINISHING
FINISHING

ROTARY SCREEN PRINTING:
Rotary screen printing involves a series of revolving metal cylinder, each with revolving screens, each with a stationary squeegee inside which forces the print paste onto the fabric.
Max twelve colors can be printed at the same time. The process is much quicker and more efficient. In Shahi export pvt ltd. There are 2 rotary machines

WORKING OF ROTARY SCREEN PRINTING M/C
The process of Rotary screen is feeding fabric onto the rubber blanket. As the fabric travels under the rotary screens, the screens turn with the fabric. Print paste is continuously fed to the interior of the screen through a color bar or pipe. As the screen rotates, the squeegee device pushes print paste through the design areas of the screen onto the fabric.

file:///G:/intrnship%20report/Rotary%20Screen%20Printing file:///G:/intrnship%20report/Rotary%20Screen%20Printing Feeding of color to rollers

Feeding of color to rollers

TE Figure: 2 Rotary screen printing m/c

* Rotary m/c is available to print 12 colours at ones. * Darkest colour is printed first and lightest colour at last. * Printing roll pressure is controlled by hydraulic pressure head. * The speed of the roller is 100 rpm. * Printing colours are pumped in to the rotary roll through pipes. * The colour is then spread over on the fabric through blade placed inside the rolls.

CURING
The fabric is then forwarded to heated segment @ 85-90 degree where the colours are dried up. * To retain a good printed mark * Prevent printed goods from marking off * Rate of drying is very important * Bleeding occurs if the drying rate is too slow

WASHING OFF
SOAPER
These textile machine give a wash to textile. Fabric are washed at several stage. Open width soaper machine are used to give wash to them, after the process of dyeing and printing. It cleans the cloth to give it a fine look.
For removal of excess colour Printing glue from the printed fabric
Last stage of printing operation. * Printed goods are rinsed with cold water. * Removes thickening chemicals and surplus unfixed dyestuff * A soaping treatment usually follows