IlSHIN Dyestuffs
Eco-friendly dyes for a beautiful future
Eco-friendly dyes for a beautiful future
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 |
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 |
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 |
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 |
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 |
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 |
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 |
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 | - |
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 |