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QUESTIONS |
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ANSWER |
| DYE |
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Q: It is rather hard to level dyeing with blue 19. Is there any proper method, dye and chemicals to dye with no head-ache ? A: Blue 19 is a vinyl sulphon based dye with brilliant shade and widely used. Due it’s reactivity - substantivity, it creates problems. When Blue 19 is dissolved in water, it is in sulfato ethyl sulfon form, whose water solubility is very high but very low affinity to the fibre. By the addition of alkali, it converts to vinyl sulfon form, whose solubility is very low but high affinity to fibre. That means it attacks to cotton very rapidly. Kimsoline Blue Rsp has high solubility in vinyl sulfon form so it does not create any specks on the fabric. Besides dyestuff, we advise, an anionic dispersing/levelling agent to ensure level dyeing. PES-CLEAN is a powerfull dispersing-levelling- for this purpose. We also recommend to add 5 % of soda ash (never alkali) at 30 C and raise the temperature as 1 C/ min (cotton), 0,5 C/ min ( viscose) to 60 C . |
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Q: My reproducibility rate with Turquoise (Blue 21) shades is very low and washing time is rather long. What measures should I take to improve my dyeings. A: Turquoise blues are phtalo cyanine based dyes with copper or nickle in the chromophore. Turquoise blue dye molecules are double size of ordinary bifunctional dyes. So for the level dyeing, these big molecules need high energy-that means 80 C dyeing temp. - and long time - that means 60 - 90 min. - for proper and uniform migration and fixation. If the conditions are not followed fully, for example 60 C or 30 min., dye will not be fixed and will be washed out during rinsing time, hence low repeatibility and long washing period. |
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As mentioned in previous paragraph, size of Turquoise dyes are rather huge and solubility in water is low. Solubility is more reduced whenever electrolyte is added into solution and make deposition of dye on fabric surface as spots. Naphthalene sulphonate based surfactants does not solve spotling problem. PES-CLEAN is very active dye dispersing and solubilizer fort his purpose. Advised amount is 0,7 g/L . Half into dye dissolving tank and rest into dyeing machine. |
DECOLORIZATION AND PARTIAL STRIPPING Q: It happens sometimes to strip the dyeing partially or fully. Please advise me an effective recipe. A: In case of incorrect matching of desired shade, or unlevel dyeing, partial or full decolorization is necessary. Partial Stripping 10 - 30 % Reduction Depending upon the degree of decolorization, Soda ash 10 - 20 g/L Exolube NC 1,0 g/L Exoline 3025 2,0 - 3,0 g/L Liquor Ratio 1:10 Temp., C 95 Time., min 30 - 60 Full Stripping Megaclear 12 2 - 4 g/L NaOH, solid 4 - 5 g/L Exolube NC 1 - 2 g/L Temp., 95 C Time., 60´ In case Turquoise HF-G, Megaclear 12 and NaOH amount is increased by 30 percent. |
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Q: a) During the dyeing of dark shades, color fixing changes the shade, which creates head-ache. b) We occasionally come across the need for de-fixing in order to make shading. What should I do, for trouble-free stripping of fixing agent. A: a) In case of Kimsoline dyes, dye- fixing is not required, if advised dyeing processes are applied and thouroughly washed by FLASH SOAP 1011. If fixing is necessary, Colorfix NF 250 can be safely used with no shade change. It is formalin free. Colorfix NF 250 % 0,5 - 0,7 pH = 7 Temp., 50 C Time., 20` Cationic or nonionic softeners can be also given in the same bath. b) In case of need defix of Colorfix NF, acidic treatment is applied Acetic Acid, 85% 2 - 5 ml/L Exolube NC 2 - 3 ml/L Temp., 80 C Time, min 20 - 30 In order to remove thouroughly cationic fixing agent before shading fabric is washed with Exolube NC 1 ml/L Temp., 95 C Time, 30 min |
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Q: We are producing PES/VIS melangefabric and jet dyed fabric. We check the washing fastness before sending the fabric, but two monts later we receive reclamation. What is the reason? A: In Physics, sublimation is the phase, from solid to gas without passing the liquid state. In case of dyed polyester fibers, dispers dyes migrate from the core of fibre and passes into atmosphere and stain the neighbor fibre, when the fabric is treated at above 150 C , like heat setting, ironing or post curing. S Type : Excellent sublimation fastness SE Type: Relatively good sublimation fastness and good levelling property E Type : Poor sublimation fastness but excellent levelling property. Sublimation fastness of polyester dying also depends on - Dyeing strength, - Reduction clearing efticiency, - Heat set temp. - Finishing chemical. If dyeing depth is very low, i.e. in pale shades, even E type dyes have good fastness as shown below. A strong reduction clearing also helps to reduce sublimation staining. Megaclear 12 is a very strong and odor-free chemical Megaclear 12 0,5 g/L NaOH, fl. 2,0 g/L Exolube NC 0,5 g/L Temp, 95 C Time, min 20 Even with S type dyes and efective reduction clearing, fastness properties may not be satisfactory, especially during storage period of fibre/fabric, after 2 - 3 months. This problem is named as Thermomigration. Thermomigration is the transfer of disperse dye from fibre/fabric into the spin-finish or finishing chemical during storage period or heat treatment. Thermo migration is triggered with nonionic ethylene oxide surfactants available in spin - fnish chemicals applied on dyed fibers during yarn manufacturing or in silicone softeners in stenter padders. During melange yarn production of dyed PES/VIS fibres, dye migrates into spin-finish chemical. After weaving, fabric is heat set in stenter and shade becomes solid. If fabric is washed at 80 C prior to setting, and remove the chemical, the result is encouraging. This explains that staining comes from the dye available in spin finish oil. |
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Reactive dyes tend to have a low substantivity and are thus readily influenced by liquor ratio. Setting the liqour ratio as low as possible will raise the fixing rate. If the circulation rate is higher and/or liquor ratio is lower, dyestuff yield will increase and recipe will result as darker. This is the main cause of Lab/Plant variation due to low speed in lab machines. In order to overcome this problem and to ensure stable shade on all machines, salt amount should be decreased around 30%, in case 1/6 liquor ratio or in between. Otherwise, recipes will be darker, off-shade and poor rubbing fastness. |
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When the water of the dye bath contains alkali metal salts, like calcium or magnesium, there is the danger that uneven dyeing, such as specking or dystuff deposition. Aside from water, ions may come from Glauber or common salt. So addition of Antisil conz (0,5 g/L) into the bleaching and dyeing baths enables the dyer to have trouble-free dyed fabrics. Antisil conz is not a simple softening agent, rather, it prevents the agglomeration of calcium and magnesium salts. Antisil keeps these ions in scattered form and prevents them to settle on the fabric which causes speck formation. In some extreme cases, Antisil conz is advised to add into the soaping solution together with FLASH SOAP. |
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Due to high circulation power pumps in cheese dyeing machines, bobbin weights vary between 1,100 - 1,500 gram. Because of high density, Calcium,Magnesium, Iron, Copper ions are not removed from cotton fully, in stead, they precipitate on yarn, during bleaching process. This sedimentation reflects itself as, -Hardness -Non uniform dyeing -Tensilstrength loss. -White, undyed spots. -Wetting-scouring agent should be foam free, has deaerating and degreasing property. If air entangled between yarn layers cannot be evacuated rapidly, foam is formed with scouring surfactant. This foam cushion is a barrier to proper flow of dye liquor and hence non uniform dyeing. Natural oils and waxes of greige cotton should be emulsified or saponified. Otherwise, undyed white spots exist. We advise 2 scouring detergent fort his purpose. Ewet RPN : Paste form, foam - free, wetting-scouring and degreasing agent Ewet LFG : Strong wetting , deaerating and degreasing detergent, in liquid form. BLEACHING Peroxide, 50 % 1,5 – 2,5 % NaOH,s, 1,5 – 2,0 % Antisil Conz, 1 % Ewet RPN or LFG 0,5 – 1,0 % Exolube NC (If necessary) 0,5 % Temp, C/Time 95 C – 40 min -Hot wash -Cold wash, Neutralize and antiper with, Biokill or Perkill |
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The main cause of shade variation and poor rubbing fastness is the unsufficient washing off process in bulk dyeing. Since, laboratory washing is more effective respectively, lab. fastness (rubbing and light) are better. At the end of dyeing, three parameters are available on the fabric. Electrolyte, alkali and hydrolyzed dye. Electrolyte should be subtracted from fabric, by cold water rinsing, until concentration drops 2 Beume. If hot water used for rinsing, hue of the dye changes. If salt is not eliminated effectively, substantivity of hydrolysed dye to the fabric remains high and wash-off is rather hard. So before soaping, salt rinsing and neutralizing should be realized effectively. For neutralization, acetic or formic type, volatile acids are preferred. Substantivity of hydrolyzed dye to cotton is higher at cold temp, in hard or electrolyte containing water. So we recommend, thourough rinsing and neutralizing at cold temperature and -Soap, with high dispersing, sequestering property like FLASH SOAP 1011 -Use soft salt. If salt is hard or rinsing is not sufficient, then add, Antisil Conz, 0,5%, to soaping and boiling wash liquors. Antisil Conz is a strong sequestering and dispersing agent. -Soap and Hot Wash liquors at boiling temp. Because, substantivity of hydrolyzed dye to cotton decreases at high temperature. After dyeing commence.
Drain dye with no over-flow,
Soap as ; without neutralization step - Flash Soap 1011 1 ml/L, 15 min. Flash Soap 1011 is a strong soaping agent which does not demand, neutrilization and multiple hot washes. |