printing-reactive & discharge print presentation by sukhvir sabharwal
DESCRIPTION
Hi All, Pls find PPT on reactive and discharge print which shows the difference to understand both print styles. Hope this would help you ! Best, SukhvirTRANSCRIPT
DISCHARGE PRINT TECHNIQUE FLOW CHART
DYEING OF
FABRIC
•RFD Fabric is dyed in the darkest base color
•PRINTING BY USING DISCHARGING AGENT
PRINTING BY
USING DISCHAR
GING AGENT
•Fabric is printed on rotary machine by using discharging agent(Rangolite). This chemical is mixed with color dyes
•Discharging agent discharges the dyed base color & then color dyes fill up the discharged areas
STEAMING
•This process is used to fix-up the printed color. Controlled steaming procedure will results in better fastness of color.
WASHING
•This process is used to drain out residual color from the surface of printed fabric. On an average approx 30% of printed color depth is being washed out at this stage.
STENTER &
SANFORIZING
•After washing fabric is being passed through stenter maching to apply softner & control the final width
•Sanforising is used to control the final shrinkage of fabric by passing the fabric through heated rubber rollers/blanket.
REACTIVE PRINT TECHNIQUE FLOW CHART
RFD PROCESS
•Fabric is processed till RFD stage . RFD process includes desizing / singeing / mercerization.
PRINTING BY
USING REACTIV
E COLORS
•Fabric is printed on rotary machine by using REACTIVE COLORS. These color particles have a tendency to penetrate well in to fibre structure
STEAMING
•This process is used to fix-up the printed color. Controlled steaming procedure will results in better fastness of color.
WASHING
•This process is used to drain out residual color from the surface of printed fabric. On an average approx 35-40% of printed color depth is being washed out at this stage.
STENTER &
SANFORIZING
•After washing fabric is being passed through stenter machine to apply softener & control the final width
•Sanforising is used to control the final shrinkage of fabric by passing the fabric through heated rubber rollers/blanket.
SINGEING & DESIZING• Singeing is done to burn the protruding fibres from the surface of fabric.• Singeing improves appearance as well as pilling resistance. • Desizing is used to remove the starch from fabric surface.• Desizing process improved the absorption of fabric.
Calendar Rolls( Steam Heated)
Flame is present at this place. It is passed tangentialy to the fabric surface
CONTINIOUS BLEACHING RANGE( SCOURING / MERCERISING/BLEACHING)
• Scouring is done to remove impurities like dust / kitty / husk from the fabric. This process is done by running the fabric through boiled water.
• Mercerizing is done to improve absorption of fabric. This is done by passing the fabric through NaOH( Sodium Hydroxide) at different concentration depending on the end shade required.
• Bleaching is done to improve whiteness in the fabric. There are mainly 2methods of bleaching –– Half Bleaching – done by HOCL (Hypo Chloride) solution– Full Bleaching – done by H2O2 ( Per Oxide) Solution
ROTARY PRINTING M/C• One rotary print roll is used to print one color. • Rotary m/c are available to print 10colors at once.• Darkest color is printed first & lightest color at last.• Printing roll pressure is controlled by hydraulic pressure head. • Printing color are pumped in to the rotary rolls through pipes.• The color is then spread over on the fabric through blade placed inside the
roll.• The fabric is then forwarded to the heated segment maintained @ 85-
90degree where the color are dried up.• The fabric is then collected at trolley placed at the end of rotary m/c
STEAMING M/C• This m/c is used for fixation of printing colors by passing the fabric through
high temp.• The temp. maintained is approx 100-150degrees for cotton fabrics & 150-
200degree for polyester.• Speed of m/c & heat exposure time is decided on the basis of print color
coverage. For Ex. -- For blotch prints with maximum coverage, m/c is kept as slow speed so that the fabric can get more time for heat exposure.
CLOSED STENTER• This m/c is the heart of any dyeing/printing mill.• Final width of fabric is adjusted by this m/c.• Softener is being applied by his m/c.• This m/c consists of 2parts
– Dyeing tub with mangle– Heated chambers ( 8-12)
CONTINIOUS WASHER• This m/c is used for Discharge & Procian prints.• The fabric is washed to extract the residual color from the surface of
fabric.• This m/c consists of several bath tubs containing cold & hot water.• Water is changed after every 1000mtrs to minimize the tinting of dark
colors on to the light colors.
SANFORIZING M/C• This m/c adjust the shrinkage in warp as well as weft direction. That’s why
it is also called zero zero m/c means zero shrinkage in both the directions.• The wet fabric passed b/w steam heated rubbers. • This m/c has the same effect as that of steam iron.
VARIABLE FACTORS IN DISCHARGE & REACTIVE PRINT TECHNIQUE
1.) Mercerization --- This process is used to improve the absorbency & dischargability of fabric. Any slight variation in caustic application will result in bulk lot variation.
2.) Steaming – This process is used for fixation of color. Steam is being applied in a closed chamber. To have even results the effect of steam should be even at all points but it is really impossible to maintain the same level of steam at all areas hence we get more bulk variation.
3.) AIRING – The fabric after printing is left for airing to have better development of colors. The surrounding environment does have an impact of final color fixation & hence the final color shade changes. Hence it is recommended not to perform a discharge/reactive print in high humidity or rainy season .
4.) Washing -- This process is used to drain out extra color from the fabric surface. As a rule, 1000ltrs of fabric is being used for 2000mtrs fabric & then fresh water is being used. Since the superficial color gets mixed in the water, hence migration of darker colors on lighter colors happens at this stage. In case of black & white print, this process becomes more crucial since black color migrates on to white color. Moreover, since a 2000mtrs bulk lots is washed at once, the maximum size of bulk lot is 2000mtrs only.
WHY DISCHARGE PRINT IS TERMED AS BLIND PRINTING
• The appearance of fabric during subsequent process of printing / steaming & washing changes drastically. This is being shown in subsequent slides
• We can see the final appearance after washing/finishing only • Hence we can’t determine exactly the final product outcome
due to several variable factors as advised in earlier slide.
