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아이콘IlSHIN Dyestuffs

Eco-friendly dyes for a beautiful future

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DYEING PROBLEMS

날염법
1. Unlevelness(due to dyeing conditions)

1. Ending Problems

Causes Countermeasures
unstable dye dispersion select dyes with better dispersion stability,use efficient dispersants
unsuitable dye combination pay attention to uniform dye behaviour
wrong dyeing program Optimum dyeing process Optimizing a dyeing process means adjusting the process parameters in such a way that the entire operation takes place in the shortest possible time without exceeding the tolerance limits with regard to reproducibility and levelness. This means rapid heating in the temperature ranges in which the dye exhausts slowly or is already exhausted; controlled heating when the dye exhibits a particularly high rate of exhaustion. The individual steps for an optimum dyeing process are;

- heat at the maximum rate to the threshold of the critical temperature range T1(PhaseA)
- control the rate of heating in the critical temperature range T1-T2(Phase B)
- on reaching T2(upper limit of the critical temperature range)heat again at the maximum rate to the fixation temperature (Phase C).

2. Cloudy dyeings

Causes Countermeasures
inadequate pretreatment select optimum conditions and chemicals
channeling due to irregular winding pay particular attention to winding of the material
wrong loading of the machine or bobbins(too much material, too tight winding, etc.) see above
poor circulation of the goods due to interruptions, knots, etc. adjust the machine more carefully
too much foam in the dyebath use antifoamers, e.g. Antimussol brands
wrong dyeing programme (heating, pressure, speed) Optimum dyeing process
Optimizing a dyeing process means adjusting the process parameters in such a way that the entire operation takes place in the shortest possible time without exceeding the tolerance limits with regard to reproducibility and levelness. This means rapid heating in the temperature ranges in which the dye exhausts slowly or is already exhausted; controlled heating when the dye exhibits a particularly high rate of exhaustion. The individual steps for an optimum dyeing process are;

- heat at the maximum rate to the threshold of the critical temperature range T1(PhaseA)
- control the rate of heating in the critical temperature range T1-T2(Phase B)
- on reaching T2(upper limit of the critical temperature range)heat again at the maximum rate to the fixation temperature (Phase C).

3. Pale areas

Causes Countermeasures
inadequate pretreatment select optimum conditions and chemicals
air pockets in the material (e.g. cheeses) use special chemicals, e.g. wetting agent / defoamer combinations, or greater pressure
2. Unlevelness(due to material)

1. Barriness

Causes Countermeasures
variations in temperature during fibre manufacture(texturizing), draft differences adapt dye selection
select higher dyeing temperature
select suitable carriers and chemicals
possibly set fibres at a higher temperature (Caution!)
variations in the density of the material (weaving, knitting) relax material thoroughly
3. Unlevelness(due to other reasons)

1. Skitterness

Causes Countermeasures
inadequate pretreatment (e.g. desizing) pay attention to perfect pretreatment
pay particular attention to the appropriate dyeing process and programme
fibres of different origins in the material
inadequate penetration (paler points of intersection)
poorer solidity on both components of fibre blends
irregular thread tension during weaving or warp knitting

2. Listing

Causes Countermeasures
inconsistent setting temperature select special dyes (small-moleculed)
irregular tension in the material due to weaving or warp knitting relax material thoroughly
poorly wound material pay particular attention to winding
rolled in selvedges due to irregular tension in the material (weaving, warp knitting) set the goods
size the selvedges
check the weaving or knitting machine

3. Pale areas after dyeing

Causes Countermeasures
effect of aggressive vapours (e.g. acid, chlorite, formaldehyde) efficient ventilation of vapours and gases
avoid contact with dangerous substances
4. Reproducibility

1. Deviation of shade

Causes Countermeasures
dye sensitivity to hydrolysis, reduction, electrolyte select dyes carefully, control pH exactly(buffer system)
pay attention to stability of dye to electrolytes
dye sensitivity to metal ions in the dyebath use suitable sequestering agent
dyes of different chemical constitution affect each ocher (rare) pay particular attention to selection of dyes and chemicals
dye buildup affected by chemicals (retarding effect) carry out lab tests
different dyeing programmes pay attention to consistent dyeing conditions
dye shows differences in standard conformity check supplies
unsuitable dye combination pay attention to behaviour of individual elements
sedimentation of liquid dyes stir before removal from container
bath exhaustion affected by reserve of adjacent fibre adapt dye selection and process

2. Dyeing too pale

Causes Countermeasures
different buildup of dye on different materials carry out preliminary tests with material

3. Precipitates in the dyebath

Causes Countermeasures
chemicals affect each other's action pay attention to chemical selection
dyeing produced at too low temperature check and adjust dyeing conditions
dyeing time too short
unstable chemicals pay attention to chemical selection

4. Change of shade

Causes Countermeasures
unfinished diffusion due to insufficient dyeing time at too low temperature check and adjust dyeing conditions
inadequate sublimation fastness of dye pay attention to dye selection
5. Fastness properties

1. Unexpectedly poor light fastness

Causes Countermeasures
carrier residues on fabric (inadequate thermofixation) repeat thermofixation (at higher temperature)
stained adjacent fibre adapt dyeing process, select appropriate dyes
catalytic fading due to unsuitable dye combination adjust dye selection

2. Unexpectedly poor wet and rub fastness

Causes Countermeasures
thermomigration due to finishing and softening chemicals adjust dye and chemical selection
inadequate dye fixation due to too short dyeing time or too low fixation temperature optimize dyeing process, reduction clear
stained adjacent fibre improve dyeing process
6. Spots, marks

1. Precipitates in the dyebath

Causes Countermeasures
dye precipitates due to poordispersion or dyes with poor dispersion stability pay special attention to dispersing instructions
pay attention to dye selection (dispersion stability)
use dispersants
dye crystallization due to variations in temperature in the dyebath pay attention to perfect liquor circulation
coloured spots due to dye deposits on the machine pay attention to cleanness in the machine
use of volatile carriers select suitable carriers, use overhead heating in the machine
silicones in the dyebath use silicone-free defoamers
unstable chemicals select suitable chemicals
oil and spinning preparations thorough pretreatment
oligomers in the dyebath drop dyebath hot, shorter dyeing time, use special chemicals

2. Singeing droplets

Causes Countermeasures
as a result of singeing before dyeing, fibre tips exhibit higher affinity for dyes singe after dyeing

3. Change of shade (e.g. blue spots in brilliant red shades)

Causes Countermeasures
dye is sensitive to metal ions use a sequestering agent
alkali residues neutralize the goods
finishing chemicals scour and select finishing chemicals carefully

4. Dark spots

Causes Countermeasures
solvent residues from pretreatment complete removal of solvents

5. Specks

Causes Countermeasures
contamination of the material by dyestuff dust do not store material near dyes; use lowdusting dyes

6. Dirt spots

Causes Countermeasures
contamination of the material by rust, oil, graphite, etc. pay attention to clean machines and clean working methods
7. Appearance of the goods

1. Dimensional stability (shrinkage)

Causes Countermeasures
insufficient relaxation during pretreatment adapt relaxation and setting to material in question
inadequate setting of material
lengthwise disortion caused by dyeing machine adjust dyeing machine to material

2. Creasing

Causes Countermeasures
inadequate pretreatment (scouring, relaxation, setting) select optimum pretreatment conditions
due to quality of goods (structure, e.g. tightly woven fabric, weight) adjust dyeing machine to material, select correct setting temperature, adjust stenter correctly
poor suitability of dyeing machine select more suitable dyeing machine
too heavy batch of fabric add a lubricant, e.g. lmacol brand
incorrect loading of machine
dyeing process (heating, cooling) adjust temperature programme, add a lubricant, e.g. lmacol brand

3. Chafe marks

Causes Countermeasures
mechanical friction due to overloading add a lubricant e.g. lmacol brand
rough patches in the machine
stationary material in the running machine (knots)
too high machine speed

4. Stitch distortion (knits)

Causes Countermeasures
inadequate pretreatment (relaxation, setting) selection optimum pretreatment conditions
mechanical effects, e.g. passage of goods in machine, squint seams straight seams along weft and stitches

5. Moire effects (on beam)

Causes Countermeasures
inadequate pretreatment (setting, rolling up) select suitable setting conditions
roll up carefully

6. Lustre

Causes Countermeasures
physical change in fibre due to local pressure and high temperature on material avoid prolonged contact of stationary material with the hot machine
excessive setting select suitable setting temperature

7. Handle

Causes Countermeasures
unfavourable conditions between machine and material select optimum conditions
inadequate pretreatment (relaxation, setting) can be corrected during finishing
wrong dyeing programme (temperature / time)

8. Pilling (staple fibres)

Causes Countermeasures
susceptible fibre origin (also in fibre blends) select fibres carefully, use selected softeners
inconsistent dimensional stability due to shrinkage (fibres protrude from fibre bundle) setting
8. Other problems

1. Difficulty with heavy shades on fine denier yarn

Causes Countermeasures
fibre surface select suitable dyes

2. Soiling of machine

3. Frosting on goods

4. Poor running of material in subsequent processing

Causes Countermeasures
oligomers -
9. Thermosol dyeing problems

1. Listing

Causes Countermeasures
one-sided liquor feed into the trough check injection pipe or mount a distribution plate
different nip roller pressure check rollers (pickup) regularly
unlevel migration in intermediate drying check temperature and air current over the entire width in the drier
avoid migration by using lowest possible pickup and a suitable migration inhibitor.
Select dyes with little tendency to migrate.
uneven thermosolling or fixation of dyes due to temperature differences check fixation units regularly with thermopaper or temperature sensors
use more reliable dyes with as little sensitivity as possible to temperature deviations

2. Two-sidedness

Causes Countermeasures
deflecting roller touched on one side only check entry of goods, if necessary replace roller
deflecting roller stationary set roller in motion
pad rollers not the same check Shore hardness, if necessary re-cover rollers
uneven drying from side to side check temperature and air current in drying machine

3. Dark or pale selvedges

Causes Countermeasures
one-sided liquor feed into the trough check liquor feed
narrow goods impregnated on a wide padder move to a suitable machine
worn rollers, rollers bend due to over compensation check the nip pressure, reduce pressure if necessary, change rollers if necessary, chick hydraulics
varying drying conditions over the width of the goods check the air jets and circulation
alkali residues in the goods add acetic acid to the padliquor for pH 5-6

4. Barry dyeings

Causes Countermeasures
uneven jet pressure in the drier check the air jets
inadequate evenness of tension in drier, crease formation check guidance of goods in drier
alkali residues in the goods add acetic acid to padliquor for pH5-6

5. Spots, specks

Causes Countermeasures
pale marks due to condensation drops check driers and pad-steam units regularly
overhead heating
foam spots due to excessive foaming of the pad liquor avoid high turbulence in the padding trough, use low-foaming chemicals, if necessary add antifoamers
coloured specks due to incorrect preparation of the padliquor follow instructions for preparing the padliquor exactly, filter padliquor before feeding into trough
avoid drying out of liquid dyes due to incorrect storage
alkali residues in the goods add acetic acid to padliquor for pH5-6

6. Ending

Causes Countermeasures
dye substantivity with lndigosol dyes add Lyogen WL
use a smaller volume of liquor
dye at higher fabric speed
dye sedimentation keep the liquor in motion
keep the temperature below 35°C

7. Pale points of intersection

Causes Countermeasures
poor penetration add a wetting agent to the padliquor
change the pressure of the rollers
increase impregnation time
severe migration dry more slowly
use special migration inhibitors

8. Foam formation

Causes Countermeasures
dispersants in the dye use antifoamers
residues of boiling off agent scour goods better before dyeing

9. Frosting

Causes Countermeasures
migration during thermosolling use special chemicals
fibre tips not dyed (e.g. viscose) add Lyogen V
change process, e.g. wet steaming