Colour Build-up Research Articles

Synthesis of monoazo disperse dyes derived from N-(1-phthalimidyl)-naphthalimides and their dyeing properties on polyester fabrics

PurposeThis paper aims to synthesize a novel series of monoazo disperse dyes based on N-(1-phthalimidyl)-naphthalimides by coupling with substitute anilines, naphthylamines and naphthol derivatives.Design/methodology/approachThe purification of the intermediates and the dyes was carried out by recrystallization. The structures of the synthesized intermediates and the dyes were elucidated by spectroscopic techniques. The absorption maxima, molar extinction coefficient and halochromic properties of the dyes were determined spectrophotometrically using solvents of different polarity.FindingsThe dyes were applied on polyester using a high-temperature high-pressure dyeing machine, and the dyeing performance parameters such as colour build-up on fabrics, wash fastness, perspiration fastness and light fastness were evaluated. The colour build-up was found to be very good and the wash fastness (4–5) and perspiration fastness (4–5) were excellent, whereas the light fastness was found to vary from moderate to very good (3–6).Research limitations/implicationsIt is not possible to investigate the structure of the synthesized dyes by nuclear magnetic resonance spectroscopic analysis due to the low solubility of dyes in deuterated solvents.Originality/valueA novel method for the synthesis of a new category of monoazo disperse dyes based on N-(1-phthalimidyl)-naphthalimides was developed. These dyestuffs could be used in textile printing of polyester fabrics.

Relationship between reactive group chemistry and printing properties of heterofunctional reactive dyes via screen printing

Screen printing of cotton fabric using newly synthesized azo reactive dyes was carried out in the present study. Functional group chemistry and its effect on the printing properties of cotton fabric by varying the nature, number and position of reactive groups of synthesized azo reactive dyes (D1–D6) was studied. Different printing parameters (Temperature, alkali and urea) and their effect was explored on the physicochemical printing properties e.g., fixation, color yield, and penetration of the dyed cotton fabric. Data revealed that dyes with more reactive groups and having linear and planar structures (D-6) showed enhanced printing properties. Spectraflash spectrophotometer was used to evaluate the colorimetric properties of screen-printed cotton fabric and results showed superb color buildup. Printed cotton samples displayed excellent to very good ultraviolet protection factor (UPF). Presence of sulphonate groups and excellent fastness properties may entitle these reactive dyes as commercially viable for urea free printing of cotton fabric.

Introducing Deep Eutectic Solvents as a Water-Free Dyeing Medium for Poly (1,4-cYclohexane Dimethylene Isosorbide Terephthalate) PICT Nanofibers.

Water, one of the most priceless sources of life, is becoming dangerously threatened and contaminated due to population growth, industrial development, and climatic variations. The drainage of industrial, farming, and municipal sewage into drinking water sources pollutes the water. The textile processing industry is one of the major consumers of water. Herein, the idea of water-free dyeing of electrospun poly (1, 4-cyclohexane dimethylene isosorbide terephthalate) PICT nanofibers is proposed. For this, two different deep eutectic solvents (DE solvents) were introduced as an alternative to water for the dyeing of PICT nanofibers in order to develop a water-free dyeing medium. For this, C.I. disperse red 167 was used as a model dye to improve the aesthetic properties of PICT nanofibers. PICT nanofibers were dyed by conventional batch dyeing and ultrasonic dyeing methods to investigate the effect of the dyeing technique on color buildup characteristics. Dyeing conditions such as dyeing time, temperature and, dye-concentration were optimized. Morphological and chemical characterization observations revealed a smooth morphology of dyed and undyed PICT nanofibers. The ultrasonically dyed nanofibers showed higher color strength and increased tensile strength compared to conventionally dyed nanofibers. Further, the consumption of electrical and thermal energy was also calculated for both processes. The results confirmed that the ultrasonic dyeing method can save 58% on electrical energy and 25% on thermal energy as compared to conventional dyeing.

Hetero-functional azo reactive dyes applied on cellulosic fabric and dyeing conditions optimization to enhance the dyeing properties

New dyestuff moieties are introduced in the textile industry to upgrade the quality and aesthetic properties of dyed fabric. To contribute to this research endeavor, the current project was conducted for the dyeing of cellulosic fabric via new hetero-functional reactive dyes R1 and R2 synthesized in our previous study. Optimization of different process variables (temperature, salt, and alkali concentration) and their interactive study for exhaust dyeing was explored and delineated based on a statistical tool response surface methodology. Results divulged that both dyes displayed maximum exhaustion and fixation at a temperature of 61.50°C on the cellulosic fabric. Reactive dye R1 exhibited 87.62 (±3) exhaustion and 82.85 (±3) fixation percentage at their optimum salt (29.07 g/L) and alkali (32.55 g/L) dosage while R2 displayed 81.50 (±3) exhaustion and 77.21 (±3) fixation at its optimized salt (32.55 g/L) and alkali concentrations (22.84 g/L). All process variables showed a positive and synergistic effect on the dyeing properties. Enhanced exhaustion and fixation percentage of R1 as compared to R2 may be accredited to greater planarity and less steric hindrance of R1. Both dyes presented superb color buildup showing good to excellent color fastness on cotton fabric. Future perspectives of the current study comprised the application and assessment of dyeing parameters of these new reactive dyes on polyester cotton (PC) fabric.

Comparison of the photochromic behaviour of dyes in solution and on polyester fabric applied by supercritical carbon dioxide

Photochromic textiles are of considerable interest for smart and functional textile applications due to their remarkable dynamic colour changing effect when irradiated with light of a certain wavelength. The use of resource efficient processes, such as digital inkjet printing and supercritical carbon dioxide (scCO2) dyeing techniques enables an economic production of those high-end functional products with high material costs. In this study, photochromic polyester fabric has been prepared by applying two commercially important photochromic dyes from spirooxazine (SO) and naphthopyran (NP) dye classes using scCO2-dyeing technique. The properties of scCO2 dyed photochromic fabrics were compared with the properties of the same dyes in a non-polar solvent, hexane. UV-Vis spectroscopy and a specially designed online colour measurement system capable of simultaneous UV irradiation and colour measurement were used to evaluate the photochromic colour behaviour. Both photochromic dye types embedded in textile as well as in solution showed significant reversible colour changing properties when exposed to UV light and revert to their original non-coloured form when the UV light is removed. The scCO2 dyed polyester fabrics exhibited similar trends of colour build-up as in solution, while contrasting behaviour was observed in terms of colour changing rates compared to their behaviour in solution.

A waterborne bio-based polymer pigment: colored regenerated cellulose suspension from waste cotton fabrics

Waterborne bio-based polymer pigments are promising environmentally friendly coloring materials. In this work, novel colored cellulose suspensions applicable for coloring, labelling and anti-counterfeiting were prepared from waste cotton fabrics. It was demonstrated that cellulose regenerated from a phosphoric acid solution of waste cotton fabrics could be conveniently colored by reacting with reactive dyes. The high specific surface area of the regenerated cellulose (RC) allowed for high color build-up of up to 210 mg/g dye fixation and K/S value of up to 31. The resulting colored regenerated cellulose (CRC) suspension had typical characteristics of regenerated cellulose and was used to color polyurethane (PU). The resulting colored PU films exhibited excellent color fastness/resistance to leaching when soaked in water. This study demonstrated a way of alleviating the environmental burden of waste cotton fabrics by converting them to high value-added colored waterborne cellulose suspension. Preparation and application of CRC suspensions from waste cotton fabrics

Ultrasonic energy-assisted coloration of polyurethane nanofibers

Herein, we first time present our research on ultrasonic dyeing of polyurethane (PU) nanofibers. The PU nanofibers were fabricated by electrospinning process and were subsequently dyed following exhaust method using sonication. The two disperse dyes selected were a low-energy disperse dye (CI Disperse Blue 56) and a high-energy disperse dye (CI Disperse Red 167:1). The ultrasonic energy was used to achieve higher color build-up on PU nanofibers. The temperature/time (T/T) diagram of proposed dyeing process has been suggested; dyeing time and dyeing temperature were optimized. Color build-up properties (measured in terms of K/S values), dye fixation (%), and color fastness properties were studied in detail. The samples were characterized by scanning electron microscope (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and mechanical strength measurements. The results show 70 °C and 40 min as optimum dyeing temperature and time, respectively. The SEM, FTIR, and XRD results did not show any significant effect of ultrasonic dyeing on morphology, chemical, and crystallographic structure of PU nanofibers. Color fastness results revealed excellent light fastness, very good washing, and hot pressing fastness of both dyes.

Dyeing and characterization of regenerated cellulose nanofibers with vat dyes

Recent advancement in dyeing of nanofibers has been accelerated to improve their aesthetic properties, however, achieving good color fastness remains a challenge. Therefore, we attempt to improve the color fastness properties nanofibers. Vat dyes are known for better color fastness and their application on nanofibers has not been investigated to date. Herein, we report dyeing of regenerated cellulose nanofibers (RCNF) that were produced from precursor of cellulose acetate (CA) followed by deacetylation process. The resultant RCNF was dyed with two different vat dyes and the color attributes were examined under spectrophotometer which showed outstanding color build-up. Morphological of CA before and after deacetylation and before and after vat dyeing was investigated under TEM, FE-SEM and SEM respectively. The vat dyed RCNF were further characterized by FTIR and WAXD. Excellent color fastness results demonstrate that vat dyed RCNF can potentially be considered for advanced apparel applications.

Synthesis of temporarily solubilised azo disperse dyes containing a β‐sulphatoethylsulphonyl group and dispersant‐free dyeing of polyethylene terephthalate fabric

Disperse dyes containing a β-sulphatoethylsulphonyl group have temporary solubility and can be applied for dispersant-free dyeing of hydrophobic fibre. Six novel temporarily solubilised azo disperse dyes having a β-sulphatoethylsulphonyl group in their structures were synthesised, and their dyeing properties on polyester were investigated. As a dye intermediate, a diazo component having dibromo groups was prepared, and 4-diethylamino-4′-(2-sulphatoethylsulphonyl-4,6-dibromo)azobenzene dyes were prepared by a diazo-coupling reaction. Then, the dyes containing dicyano groups were prepared by cyanation of corresponding dyes with dibromo groups. The absorption maxima of the dyes were affected by the substituents in the diazo and coupling component rings and varied from 434 to 616 nm in dimethylformamide. Polyethylene terephthalate woven fabric could be dyed with the synthesised temporarily solubilised dyes without using any dispersants. Dyebath pH affected the K/S value at maximum absorption as well as percentage exhaustion on polyethylene terephthalate fabric, and the optimum pH was 5. The dyes gave brownish orange, red, purple, and greenish blue hues on polyethylene terephthalate fabrics, and colour build-up was good. Wash fastness was good to excellent, rubbing fastness was moderate to excellent, and light fastness was poor to moderate.

Color Build-Up and UV-Protection Performance of Encapsulated Photochromic Dye-Treated Cotton Fabrics

A spirooxazine-based photochromic dye was encapsulated by an oil-in-water emulsion, solvent evaporation method. The encapsulated dye was applied to cotton fabric by a pad-cure process with different binder types. Ultraviolet (UV) protection was increased with application of the encapsulated photochromic dye. The type of binder used affected the photochromic color build-up during UV irradiation and could modify the UV protection imparted by the encapsulated photochromic dyes on textiles.

Downhole Measurement of Methane Content and GOR in Formation Fluid Samples

Summary Formation fluid sampling early in the life of a well ensures that vital information is available for timely input to field planning decisions. For example, in subsea wells, flow assurance is a major concern, and formation fluid samples from openhole logging help operators optimize investment in both upstream and downstream facilities. When a formation fluid sample is taken from a well drilled with oil-based mud (OBM), sample contamination by the OBM filtrate is a critical factor for the accurate measurement of the sample pressure/volume/temperature (PVT) properties. A technique of monitoring sample contamination from OBM filtrate uses optical means to monitor the buildup of both color- and methaneabsorption signals during sampling. The technique provides realtime analysis of sample contamination. Methane detection is essential for condensates and lightly colored crude oils; for such fluids, the color buildup becomes difficult to detect, but the high methane content of these fluids makes possible a reliable methane-based OBM-contamination monitoring algorithm. Gas/oil ratio (GOR) is an important property of crude oil, and it is a vital input to the design of production facilities. Conventionally, GOR is measured at a PVT laboratory, and it may take many weeks before the laboratory can provide this critical information. In this paper, we describe the development of an in-situ GOR measurement technique, which uses the optical properties of methane and oil components in crude oil. With this technique, GOR can be measured downhole in real time, when the sample is taken, and without requiring phase separation. Downhole GOR has many advantages over the conventional GOR measurement techniques. It does not require tampering with the sample, which helps the operator maintain the fluid in a single phase during and after sampling. It also can aid in fingerprinting oils from different layers and provides early indications of GOR that can be compared to PVT lab results. Both the OBM contamination monitoring and the GOR algorithms work well for most crude oils. However, for heavy (dark) oils, the contamination prediction from the methane component and the GOR prediction become unreliable because of the color effect. In this paper, we describe the methodology for downhole GOR measurement, and we provide details of a decolorization technique to remove the color effect of dark oils from the methane, oil, and base channels in a downhole optical fluid analyzer tool. This technique significantly improves real-time contamination monitoring and GOR prediction results for dark oils.

Photochromic Protein Substrates

ABSTRACT A water-soluble spirooxazine may be successfully applied directly as dye to produce photochromic silk fabric. Molecular modelling, using the CAChe system, provides a good prediction of its photochromic properties. The dyed fabric shows good colour build-up under UV irradiation and reverts slowly to the original colour when the UV source is removed. It is observed that wet fabric shows better photochromic performance than after drying.

Reuse of textile reactive azo dyebaths following biological decolorization.

The objective of this work was to evaluate the feasibility of biological decolorization and reuse of textile reactive azo dyebaths with the goal of developing an in-plant, closed-loop decolorization system leading to water conservation and wastewater minimization. Decolorization of three spent dyebaths was investigated using a suspended-growth, halophilic mixed culture under anoxic conditions. A high rate and extent of color removal ranging from 77 to 90% was achieved. The three azo dyebaths and their decolorization products did not inhibit the halophilic culture. Although single dyeings using the biologically renovated dyebaths as process water resulted in highly reproducible and consistent fabric color shades, pH adjustment of the renovated dyebaths during the dyeing cycle was necessary. The extent of color removal using a biofilm reactor ranged from 86 to 95% during five repetitive dyebath decolorization and reuse cycles without any inhibition and residual color buildup. Repetitive dyeing with the same biologically decolorized dyebath for up to five cycles using a biofilm reactor and dyebath pH adjustment during the redyeing process resulted in almost identical fabric color shades as standard dyeing using fresh water. Excellent reproducibility in fabric color shades was also obtained by using biologically decolorized dyebaths in cross dyeings with different dyeing recipes. To our knowledge, this is the first report on the feasibility of biological decolorization of spent reactive dyebaths using a halophilic mixed culture and the direct reuse of the renovated dyebath as process water in the dyeing process. The results of this study demonstrate that in-plant application of closed-loop dyeing and decolorization is feasible and has the potential to not only decrease wastewater volume and treatment cost, but also minimize water use as well as the discharge of textile pollutants such as salt and dyes.

REUSE OF TEXTILE REACTIVE AZO DYEBATHS FOLLOWING BIOLOGICAL DECOLORIZATION

The objective of this work was to evaluate the feasibility of biological decolorization and reuse of textile reactive azo dyebaths with the goal of developing an in-plant, closed-loop decolorization system leading to water conservation and wastewater minimization. Decolorization of three spent dyebaths was investigated using a suspended-growth, halophilic mixed culture under anoxic conditions. A high rate and extent of color removal ranging from 77 to 90% was achieved. The three azo dyebaths and their decolorization products did not inhibit the halophilic culture. Although single dyeings using the biologically renovated dyebaths as process water resulted in highly reproducible and consistent fabric color shades, pH adjustment of the renovated dyebaths during the dyeing cycle was necessary. The extent of color removal using a biofilm reactor ranged from 86 to 95% during five repetitive dyebath decolorization and reuse cycles without any inhibition and residual color buildup. Repetitive dyeing with the same biologically decolorized dyebath for up to five cycles using a biofilm reactor and dyebath pH adjustment during the redyeing process resulted in almost identical fabric color shades as standard dyeing using fresh water. Excellent reproducibility in fabric color shades was also obtained by using biologically decolorized dyebaths in cross dyeings with different dyeing recipes. To our knowledge, this is the first report on the feasibility of biological decolorization of spent reactive dyebaths using a halophilic mixed culture and the direct reuse of the renovated dyebath as process water in the dyeing process. The results of this study demonstrate that in-plant application of closed-loop dyeing and decolorization is feasible and has the potential to not only decrease wastewater volume and treatment cost, but also minimize water use as well as the discharge of textile pollutants such as salt and dyes.