DYEING OF POLYESTER BLENDS. Limited manufacture in India Most popular blend :55/45 PET/Wool Other blend ratios : 70/30 , 20/80 - PowerPoint PPT Presentation
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DYEING OF POLYESTER BLENDS
• Limited manufacture in India• Most popular blend :55/45 PET/Wool• Other blend ratios : 70/30 , 20/80
• 55:45 blend –warp and weft blended yarn• Polyester Rich Blend: 70/30 (textured 100% PET
• High temperature –not suitable• Low energy DDs-low sublimation fastness• Medium energy dyes –pale shades or dyeing at
1060C• High energy dyes- not suitable –but can be used
for max. colour yield and fastness is required –applied to 1300C prior to PET/wool blending
• pH : 4.5 – 5.5.
Wool Dyes:
• Acid and premetallised dyes – most suitable• No staining on PET• Build up ~40 - 500C• Complete exhaustion at boil in 30 min.• Dye selection is not critical• Wet fastness is important : 1:2 metal complex
preferred• Dyeing pH: 4.5 –5.5
Mixture dyes:• Disperse/wool dye mixture- available since 1985,
suitable for 55:45 PET/wool• Advantages:
*simplified selection, reduced weighing/handling of dyes* good reproducibility (from batch to batch or lab.to bulk scale)* tone and tone dyeings as a result of good compatibility of acid and disperse dyes within each mixture*suitable for computer colour matching
Single dye class: e.g. reactive disperse dyes• Developed dyes show poor light fastness, • not commercially suitable
Minimisation of damage to wool
• The advantages of high temperature dyeing above 1100C are– Fast deep shades– Shorter leveling time– Better levelling– Less staining of wool
• Disadvantages – Wool degradation –reduction in strength, elongation,
abrasion resistance, yellowing
• Therefore, to protect the wool component
during high temperature dyeing,– Most common agent HCHO (5% owf) allows
dyeing at• 1050C for 4 hrs
• 1100C for 3 hrs
• 1150C for2 hrs
• 1200C for 1 hr
– pH: 3.5-4.5
Recommended dyeing times
• 1000C for 120-150 min with carrier, no formaldehyde
• 1060C ,90 –120 min with carrier and without formaldehyde
• High temperature dyeing is recommended for deep shades –yellowing is not so critical
Precautions for formaldehyde use
– Shades of some dyes are affected -careful dye selection
– HCHO vapors are potentially hazardous -restricted use by health and safety considerations
• Therefore, agents which will release HCHO during dyeing (in-situ release) are preferred. E.g DMEU -HCHO release above 00C
Dyeing methods:
• One bath dyeing method with disperse and acid or metal complex dyes
• Dye selection:– Disperse dye –low energy ->minimum
staining of wool –easily removed by after wash
– Acid or metal complex –not so critical
General dyeing recipe
• X% disperse dye
• Y% acid/metal complex dye
• Z% carrier
• 1 –2% dispersing agent
• 5 -10% glauber’s salt
• pH :4.5 –5.5 with acetic acid
Dyeing procedure
• Set bath with auxiliaries• Preheat 10 –20 min at 50 -700C• Add disperse and dissolved acid dye• Treat for 10 min• Raise temperature to boil or 103-1060C 30-45 min• Dye for 1½-2hrs depending on depth of shade• Cool, cold and hot rinse –shading 80 -1000C
• Staining of wool with disperse dyes cannot be avoided even if the process is carried out with most suitable dyes under the most favourable conditions
• Disperse staining on wool –poor fastness –must be removed completely
• One-bath method –reduction clear is not possible• After wash: 1-2 gpl non-ionic detergent, pH 5-6
with HAC’, 20-30 min at 600C, good rinse• With deep shades, repeat the above process
Two bath process• Used for deep shades -particularly navy
and black• Dye polyester component with
– X % disperse dye– Y% carrier– 1 –2% dispersing agent– pH 5-6 with HAC’– Maximum temperature :103 -1060C or boil– Cold rinse
Reduction clearing:
– 3 gpl hydrose– 0.5- 1 ml/l ammonia(25%)– 0.5-1 gpl non-ionic emulsifying agent– For 30 min at 45 -500C
• Good rinse, acidify with HAC’
• Dyeing of wool component
Thermosol dyeing
• Not common• Can be used for coloration of PET component
only• Wool component is dyed seperately (detail sin page
256-257)
• Dry heat treatment:– 190 -2000C for 45 –60 secs
– Not harmful to wool except slight yellowing
– Less wool staining
Correction of faulty dyeings• Faulty shades can be levelled or partially
stripped with • X gpl carrier• 2-4% levelling agent for wool• 1 –2% emulsifying agent• pH 5-6% with HAC’
– Treatment at boil for 1 –2 hrs or 103 -1060C for 1 –1 ½ hrs
If only shade on wool is to be corrected, carrier is not necessary