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Dyeing Process (dyeing + process)
Selected AbstractsDyeability improvement of polyester pretreated with some alkoxidesJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2008A. Bendak Abstract The influence of some alkoxides in alcoholic media, having various dielectric constants, on the physical and mechanical properties was thoroughly studied in a previous work to attain silk-like polyester fibers. In this investigation, the dyeability behavior of this silk-like polyester is tried. Both immersion and padding techniques are applied in the treatment. The dyeability of the pretreated polyester fabric with disperse dyes shows some progressive improvements with lowering the dyeing temperature and/or decreasing the time of dyeing attained. Ethoxide is found to be more effective in enhancing the dyeability of polyester fabric than either methoxide or propoxide. Dyeing of the pretreated polyester fabric at the boil without using carriers or conducting high temperature/high pressure dyeing is also possible. Washing and crocking fastness are relatively enhanced. Physicochemical investigations of the dyeing process and a mathematical analysis for evenness are given. A decrease in the half dyeing time and an increase in the rate of dyeing of the pretreated polyester as compared with the untreated one are noticed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Dye,fiber interactions in PET fibers: Hydrogen bonding studied by IR-spectroscopyJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007Karen De Clerck Abstract Dye,fiber interactions are studied in poly (ethylene terephthalate) fibers by FT-IR spectroscopy. It is shown for the first time that DRIFTS (diffuse reflectance infrared Fourier transform spectroscopy) serves as an easy applicable and accurate technique for the study of fibrous structures. This article focuses on the possible hydrogen bond interactions in the dye,fiber system, where the PET fibers are dyed with anthraquinone-based disperse dyes. The dyes and related anthraquinone structures are studied in both the dilute solution state, the solid state, and as present in the PET fibers. It is proven that 1-amino anthraquinones show strong "chelate-type" intramolecular hydrogen bonding in all three states. In the fibers an important supplementary intermolecular hydrogen bonding with the CO groups in the PET fiber is observed. The extend of hydrogen bonding seems to be prone to dye concentration variations. Further analysis by modulated differential scanning calorimetry links the hydrogen bonding to an intrinsic plasticizing effect of the dyes affecting the dye diffusion process. This thus offers a tool for the fundamental understanding of the dyeing process and possible observed differences in dyeing behavior in dye,fiber systems. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 [source] Direct filtration of Procion dye bath wastewaters by nanofiltration membranes: flux and removal characteristicsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 12 2003Ismail Koyuncu Abstract The treatment and reuse of industrial wastewaters by membrane processes has become more attractive in the last few years due to constraints on water usage. The aim of this study was to investigate the direct filtration of reactive dye house wastewaters by nanofiltration membranes based on permeate flux, and sodium chloride and colour removal. Experiments were performed using both synthetic and industrial dye bath wastewaters with the fluxes of the industrial dye bath wastewaters lower than those of the synthetic solutions. The effects of operating conditions such as pressure and pH were assessed. Studies with DS5 DK type (polysulfone,polyamide) membranes showed that nanofiltration membranes are suitable for direct treatment of wastewaters and the permeate quality was appropriate for reuse in the dyeing process. Pre-treatment and neutralisation were important for recovery of large amounts of salt and water from the permeate stream. Neutralisation of the solution with HCl rather than H2SO4 gave a better permeate from the point of view of the reuse. The highest permeate flux and colour removal and the lowest salt removal were achieved with the HCl neutralisation. Copyright © 2003 Society of Chemical Industry [source] Dyeing and fastness properties of phthalimide-based alkali-clearable azo disperse dyes on poly(ethylene terephthalate)COLORATION TECHNOLOGY, Issue 6 2009Joonseok Koh The properties of a series of phthalimide-containing azo disperse dyes and azo dyes with N -methyl phthalimide moieties in their diazo component were investigated and compared when used to colour polyethylene terephthalate. The N -substitution of the phthalimide gave a hypsochromic effect on the colour change and better colour yields on poly(ethylene terephthalate) fabrics, probably because of the electron-donating property of the methyl group and the higher hydrophobicity of phthalimide-containing azo dyes compared with those containing phthalimide moieties. The results show that phthalimide-based azo disperse dyes have excellent dyeing fastness properties and that high wash fastness can be achieved using alkali clearance. This alternative clearance method is important for reducing the environmental impact of the dyeing process by replacing reductive clearing and, in particular, by removing the need for sodium hydrosulphite, which creates a high biological oxygen demand when released in conventional disperse dyeing effluent and which generates aromatic amines. [source] Effect of enzyme treatment and dyeing on the mechanical properties of linenCOLORATION TECHNOLOGY, Issue 5 2009C W Kan In this paper, different concentrations of cellulase enzyme were used for treating linen fabrics. The pretreated linen fabrics were dyed using a bifunctional reactive dye at various concentrations. The effect of enzyme treatment, together with the dyeing process on the low-stress mechanical properties of the linen fabric, was then investigated. The low-stress mechanical properties were assessed quantitatively, including the tensile, shearing, bending, compression and surface properties of the enzyme-treated and dyed linen fabrics. The results revealed that the enzyme treatment with subsequent dyeing could alter these properties to a greater extent, depending predominantly on the concentration of enzyme used. [source] A study on the spectral changes of reactive textile dyes and their implications for online control of dyeing processesCOLORATION TECHNOLOGY, Issue 1 2009Jorge G Santos Evidence is presented that confirms the colour changes of a widely used trichromatic mixture of bifunctional reactive dyes (Levafix CA) under alkaline conditions, showing that they occur slowly and throughout the dyeing time, and not instantly after alkali addition to the dyebath. Thus, it is impossible to determine the specific absorptivity of the dyes at each moment of the dyeing process. An investigation into the relationship of the type of reactive group to the dye and the visible spectral changes over time was undertaken. Model reactive dyes were studied. The samples collected from the simulated dyebaths were monitored online using an automated system and their absorption on the whole of the visible spectrum was measured. The studies of dyes that included halo- s -triazinyl groups revealed the existence of hypochromic shifts in the spectra of the dyes in the presence of an electrolyte (sodium chloride or sodium sulphate) and bathochromic and hyperchromic shifts, when evaluated in the presence of alkaline agents. However, the vinylsulphonyl derivatives present a more stable spectral profile. The use of buffer solution at pH 5 was an efficient method to stabilise the absorption profile of Levafix CA trichromatic samples. [source] Review of the process development aspects of electrochemical dyeing: its impact and commercial applicationsCOLORATION TECHNOLOGY, Issue 3 2007M Anbu Kulandainathan This review discusses the recent progress made in both direct and indirect electrochemical dyeing processes and the parameters that control the dyeing process. [source] Analysis of sulphur-containing indigoid dyes as leuco forms by NMR spectroscopyCOLORATION TECHNOLOGY, Issue 6 2006Gundula Voss The NMR spectra of different types of sulphur-containing indigoid dyes as leuco forms (i.e. reduced forms or ,vats') in deuterium oxide are recorded and discussed. NMR spectroscopy provides an expeditious technique for identification, structure elucidation and purity control of these dyes. The regio-selective exchange of halogen for deuterium or hydrogen in indigo derivatives was successfully adapted to thioindigos and [indole-(2,)]-[thionaphthene-(2)]-indigos. The reaction is useful as supplementary method for structure analysis and renders access to new selectively deuterated dyes. Care must be observed with the concentration of reducing agents and pH values in vat dyeing process in order to avoid further reduction of the leuco forms. The ,overreduction' of leuco forms of [acenaphthene-(1,)]-[thionaphthene-(2)]-indigos was followed by NMR spectroscopy and interpreted. [source] High affinity, high efficiency fibre-reactive dyesCOLORATION TECHNOLOGY, Issue 4 2006Brent Smith A straightforward two-step method for modifying commercial dichlorotriazine-based fibre-reactive dyes prior to their use in the dyeing process can greatly improve affinity and fixation efficiency on cotton, and reduce the salt requirements. The modification used in this study involved prereacting the commercial dyes with either cysteine or cysteamine followed by reaction of the resulting intermediate with cyanuric chloride. Cotton fabric dyed with the modified dyes had technical properties that were essentially equal to those obtained from the unmodified commercial dyes. [source] Dye diffusion and the phenomenon of barriness on polyamide fabricsCOLORATION TECHNOLOGY, Issue 2 2004L Razafimahefa Dyed polyamide fabrics tend to exhibit barriness, particularly when acid dyes of good wet fastness are used. The causes of this phenomenon have been investigated by studying the diffusion kinetics of the dyeing process. The conditions used in the pretreatment of the yarn have been considered, in particular the effect of mechanical and thermal conditions during thermal pretreatment. It has been demonstrated that barriness is dependent only on the kinetics of diffusion. If drawing is increased, the rate of dye diffusion is reduced, whereas an increase in the texturising temperature tends to increase it. The influence of dye diffusion decreases as the dyeing temperature rises. The traditional practice of dyers to attempt to reduce barriness by raising the dyebath temperature very slowly therefore makes matters worse. To reduce barring it would be preferable to introduce the dyestuff to the dyebath only once the dyeing temperature has been reached. [source] A study on the spectral changes of reactive textile dyes and their implications for online control of dyeing processesCOLORATION TECHNOLOGY, Issue 1 2009Jorge G Santos Evidence is presented that confirms the colour changes of a widely used trichromatic mixture of bifunctional reactive dyes (Levafix CA) under alkaline conditions, showing that they occur slowly and throughout the dyeing time, and not instantly after alkali addition to the dyebath. Thus, it is impossible to determine the specific absorptivity of the dyes at each moment of the dyeing process. An investigation into the relationship of the type of reactive group to the dye and the visible spectral changes over time was undertaken. Model reactive dyes were studied. The samples collected from the simulated dyebaths were monitored online using an automated system and their absorption on the whole of the visible spectrum was measured. The studies of dyes that included halo- s -triazinyl groups revealed the existence of hypochromic shifts in the spectra of the dyes in the presence of an electrolyte (sodium chloride or sodium sulphate) and bathochromic and hyperchromic shifts, when evaluated in the presence of alkaline agents. However, the vinylsulphonyl derivatives present a more stable spectral profile. The use of buffer solution at pH 5 was an efficient method to stabilise the absorption profile of Levafix CA trichromatic samples. [source] Review of the process development aspects of electrochemical dyeing: its impact and commercial applicationsCOLORATION TECHNOLOGY, Issue 3 2007M Anbu Kulandainathan This review discusses the recent progress made in both direct and indirect electrochemical dyeing processes and the parameters that control the dyeing process. [source] | ||||||||||