High Color Depth Research Articles

Low temperature non-aqueous dyeing of wool fiber with reactive dyes: A sustainable and eco-friendly method

Conventional wool dyeing usually performed at a boiling point, often destroys the wool structure, consumes plenty energy and water. Aiming at realizing the sustainable cleaning coloration of wool dyeing and keeping the excellent natural quality of wool fiber, a green dyeing technology, non-aqueous dyeing, has been successfully applied. The effect of acid-pretreatment on the reactive dye adsorption behaviors was explored and optimized the dyeing parameters by the design of experiments as well as a single factor screening way. The results demonstrate that acid-pretreatment improved the dye exhaustion rate to 99.79 % effectively by lowering the pH value of wool fiber and increased the dye fixation rate from 75.33 % to 86.93 % by enlarging the dyeing channel. Additionally, the factors that affected wool dyeing were analyzed, approving additional acetic acid had the most significant effect on the wool dyeing. The optimal wool dyeing condition included 1 % on the weight of fiber (o.w.f) acetic acid indicating low-temperature wool dyeing was achieved by this non-aqueous dyeing system at 85 °C for 60min. Furthermore, a higher color depth, constant mechanical properties, good rubbing fastness, and soaping fastness were obtained by this dyeing method. Compared with conventional dyeing, 24.28% energy consumption, 32.50% water usage, and 31.36% wastewater were reduced by this dyeing method. Therefore, sustainable non-aqueous dyeing technology is eco-friendly and has the potential to protect the wool structure from being damaged in the dyeing process.

Supercritical CO2 as a potential tool for the eco-friendly printing of meta-aramid

Large degree of orientation, crystallinity, and high glass transition temperature of aramid make the fibers exhibit ultra-high strength, high modulus, high temperature resistance, acid and alkali resistance, light weight and other excellent properties. However, the resulting poor dyeability and water pollution problems of aramid greatly limits its application in protective areas. An eco-friendly supercritical CO2 assisted printing strategy for meta-aramid was developed firstly in this study. The effects of treatment temperature, time, pressure and dye concentration on the printing properties were investigated. The obtained results showed that the K/S values of the printed meta-aramid increased with the enhancing of CO2 temperature, treatment time and CO2 pressure. Compared to tradition printing, higher color depth can be obtained by supercritical CO2 assisted printing with 40% sodium carboxymethyl cellulose and 20% guar gum as original paste. The K/S values of the meta-aramid with Cationic Pink X-FG in supercritical CO2 was 12.18 while that of the samples with Cationic Yellow 5GL was 5.42. Washing and rubbing colorfastness rated above 4 were reached at 180 °C for Cationic Pink X-FG and at 160 °C for Cationic Yellow 5GL in supercritical CO2. In addition, up to 99% outline sharpness and acceptable stiffness, air permeability and mechanical properties was obtained, which demonstrated that the meta-aramid fabrics with supercritical assisted printing could better meet the wearability requirements.

Preview the Products on Display at Display Week 2023

Preview the Products on Display at Display Week 2023

A 10-Bit 20 Channel LCD Column Driver Using Compact DAC

A 20-channel liquid crystal display (LCD) driver architecture is implemented with [Formula: see text]m CMOS technology. This work presents a novel design of 10-bit compact and high-resolution two-stage DAC to improve the linearity and uniformity of each channel performance. A complete column driver, including a compact DAC, low power buffer, global R-string and multiplexing circuit design, is implemented, and the layout of this 20-channel, 10-bit LCD driver is generated using [Formula: see text]m CMOS technology. All the circuit blocks of the proposed LCD column driver were simulated using the EDA tool HSPICE and layout generation by Laker. This work also realizes a high-performance class AB operational amplifier with a gain of 140[Formula: see text]dB for the proposed LCD driver. The 10-bit compact LCD driver has a 1.4 mV LSB and an output voltage of 1.7 V is achieved for the input range of 0.25–1.7[Formula: see text]V. The compact DAC voltage selector with decoder in this design uses fewer switches in comparison to conventional tree-type RDAC, occupying a smaller chip area with fast response. The proposed design is sufficiently robust for high-color depth and resolution LCD driver applications. The experimental results exhibit maximum differential nonlinearity (DNL) and integral nonlinearity (INL) of 0.065 LSB and −0.12 LSB, respectively. The one channel area is [Formula: see text]m and the settling time is [Formula: see text]s for the [Formula: see text] and 20[Formula: see text]pF driving load.

Facile Synthesis of Novel Disperse Dyes for Dyeing Polyester Fabrics: Demonstrating Their Potential Biological Activities.

Original work showed the composition of the dyes and the antimicrobial/UV protective properties of a series of dyes obtained in our laboratories over the past twelve years in an easy way using microwave technology and their comparisons with conventional methods. The results we obtained clearly indicated that by using the microwave strategy, we were able to synthesize the new disperse dyes in minutes and with a much higher productivity when compared to the traditional methods, which took a much longer time, sometimes up to hours. We also introduced ultrasonic technology in dyeing polyester fabrics at 80 °C for an environmentally friendly approach, which was an alternative to traditional dyeing methods at 100 °C; we obtained a much higher color depth than traditional dyeing methods reaching 102.9%. We presented both the biological activity of the prepared new dyes and the fastness properties and clearly indicated that these dyes possess biological activity and high fastness properties.We presented through the results that when dyeing polyester fabrics with some selected disperse dyes, the color strength of polyester fabrics dyed at high temperatures was greater than the color strength of polyester fabrics dyed at low temperatures by 144%, 186%, 265% and 309%. Finally, we presented that a ZnO or TiO2 NPs post-dyeing treatment of polyester fabrics is promising strategy for producing polyester fabrics possess multifunction like self-cleaning property, high light fastness, antimicrobial and anti-ultraviolet properties.

Ultralow emission micro-printing process for PET fibers using liquid disperse dye

The commercial powder disperse dye used for printing polyester fabrics exhibits many environmentally-unfriendly properties, especially the associated high wastewater emission. In this study, three kinds of liquid disperse dyes (C.I. Disperse Blue 291:1, (L-DB); C.I. Disperse Red 179, (L-DR), and C.I. Disperse Orange 30, (L-DO)), two kinds of binders (A and/or B), and a micro-printing process, were applied to polyester fabric, with the goal of reducing freshwater consumption while maintaining color fastness. The influences of rheological and printing performance and color fastness were studied. Home-made liquid dyes of L-DB, L-DR and L-DO were found to exhibit higher color depth, excellent color fastness, and ultralow emission of wastewater and waste residual during the micro-printing process. The binder comprised of silicone-modified polyacrylate was observed to increase dye uptake, reduce dye sublimation, and improve color fastness. The liquid dyes of L-DB, L-DR and L-DO also exhibit stable and better rheological properties, which appeared to have little effect on the viscosity of printing pastes when compared with commercial powder disperse dye of Blue 3GFL (C.I. Disperse Blue 291:1), Red 2B (C.I. Disperse Red 179) and Yellow brown S-4RL (C.I. Disperse Orange 30), respectively. Results of this micro-printing process indicated that it is an environmentally clean production technology.

The Action Difference of Lasiodiplodia theobromae on Infecting and Dyeing Poplar Wood in Spatial Growth

Many factors affect the driving force of fungal growth and secretion. To compare the differences of Lasiodiplodia theobromae infected poplar wood, the changes of physical and chemical properties of vertically and horizontally infected poplar wood before and after dyeing were analyzed, and the infection characteristics were studied in this paper. The horizontal infection was more effective than the vertical infection in terms of infection depth, color depth, and microscopic hyphal invasion. The mycelium first intruded into the earlywood tissue and began to secrete a large amount of pigment after twenty days. The crystallinity of mycelium decreased slightly, and the difference in weight loss rate was negligible. The initial contact angle of the dyed specimen on the horizontal infection increased drastically in distilled water, but there was almost no difference between varnish and natural coating. The horizontal infection was more efficient than the vertical infection and had a higher color depth and a better induction effect, which is crucial in future microbial dyeing.

Improved inkjet printability of dye-based inks through enhancing the interaction of dye molecules and polymer nanospheres

Inkjet printability of dye-based inks including stability, jetting morphology, and color performance is difficult to maintain due to the strong dye molecular interaction. Herein, carboxyl-rich polymer nanospheres were introduced to the dye-based inks, forming a novel kind of multilayer dye/polymer nanospheres to enhance the inkjet printability. Disperse dyes were firstly loaded into poly (styrene-butyl acrylate-methacrylate) nanospheres at 95 °C, and then encapsulated by poly (styrene-methacrylate) polymer layer through seed polymerization to form multilayer structure. The results showed that hydrogen bonds were formed between disperse dyes and nanospheres, and the interaction was enhanced when more carboxyl groups were polymerized on nanosphere surface. Moreover, due to the high surface carboxyl group content, the stability was significantly improved in comparison with disperse dye suspension. After inkjet printing, the dye/nanosphere dispersion showed more stable droplet formation and higher color depth. Besides, because of the self-curing ability of polymer nanospheres, satisfactory fastness was obtained for practical application. The results from this study can promote the optimization of dye-based ink formulations, and show great potential in obtaining high quality inkjet printing products.

Bio-Inspired Coloring and Functionalization of Silk Fabric via Laccase-Catalyzed Graft Polymerization of Arylamines

Generally, dyeing and finishing of Bombyx mori silk fibers were proceeded at high temperature, which has the disadvantages of overmuch energy-consumptions. In the present work, bio-inspired in situ coloring and functionalization of silk fabric were carried out via laccase-catalyzed graft polymerization of arylamines, including aniline (ANI) and p-phenylenediamine (PPD). p-Hydroxyphenylacetamide (PHAD) as the model compound of tyrosine residues in silk fibroin (SF) was used to explore the mechanism of graft polymerization by means of MALDI-TOF MS. The actions of the dopants of sodium dodecyl benzene sulfonate (SDBS) and sodium p-aminobenzenesulfonate (ABSA) on the enzymatic treatment were also concerned. The results indicated that laccase might initiate the self-polymerizations of ANI and PPD, respectively, and formed the copolymers of arylamine and PHAD subsequently. High color depth and color fastness were obtained after incubation silk fabric with laccase and arylamines, companying with a noticeable pH-responsiveness. The laccase-mediated treatment endowed silk fabric with antibacterial and antioxidant abilities, meanwhile, the addition of dopants of SDBS and ABSA promoted the enzymatic finishing. Enzymatic graft polymerization of arylamine onto silk fibroin provides a novel approach for dyeing and functionalization of silk fabrics under mild treating conditions.

Functionalization of silk by silver nanoparticles synthesized using the aqueous extract from tea stem waste

Silk has poor antibacterial and UV protection properties which limit its application fields. Silver nanoparticles (AgNPs) have attracted great attention due to their excellent antibacterial activity. This work proposed a green and efficient way to prepare AgNPs from silver nitrate using the aqueous extract from tea stem waste, and a functional finishing of silk material with the resulting AgNPs by an immersion technique. AgNPs prepared at pH 9 and 40℃ exhibited ultra-fine particle size (<20nm), good dispersibility and good storage stability. When silk was treated with AgNPs at pH 3 and 80℃ for 40min, it displayed high silver content and color depth. The antibacterial and UV protection ability of AgNPs treated silk fabric of crepe de chine (52g/m2) increased as the silver content of silk increased. At a silver content of 3.64mg/g, the antibacterial rate of treated silk against Escherichia coli and Staphylococcus aureus was as high as 99%, and it was above 92% even after 20 cycles of washing under a neutral condition. At the same silver content, the UV protection factor of treated silk reached 21.3, being classified as “good protection”. The present study not only presents a novel approach for the functionalization of silk material using biosynthesized AgNPs, but also implements the reuse of tea stem waste.

Antibacterial Functionalization of Silk Fabrics following in Situ Coloring with Diazo Salts

ABSTRACT Bombyx mori silk fabrics are generally dyed with acid dyestuffs at high temperature, and it has the disadvantages of overmuch energy-consumption. In the present work, in situ coloring of silk fabric was performed using diazo salts of aromatic amines, aiming at achieving high color fastness with less energy consumption. Subsequently, graft copolymerization of methacrylatoethyl trimethyl ammonium chloride (DMC) with silk fabrics was carried out using ammonium persulfate (APS) initiator, for further endowing silk with antibacterial ability. The results from liquid chromatography-mass spectrometry (LC-MS), FTIR and Raman spectra verified the formation of the azo dyestuff from diazo salts and tyrosine model compound. The silk fabric exhibited high color depth and satisfactory color fastness after in situ coloring. For the fabric coupled with diazo salt of 4-vinylphenylamine (DVA), the introduced vinyl groups might further graft copolymerize with DMC, resulting in a noticeable antibacterial effect with the antibacterial ratio of 96.38%. Meanwhile, no strengthen loss was detected after the combination treatments. The combined use of in situ coloring and APS-initiated cascade antibacterial functionalization provides a novel and energy-saving approach for dyeing and functionalization of silk fabrics under mild treating conditions.

Microwave-assisted improvement in dyeing behavior of chemical and bio-mordanted silk fabric using safflower (Carthamus tinctorius L) extract

ABSTRACTThe resurgence of natural colorant in textile dyeing is gaining popularity due to their ecofriendly benefits. The current study has been concerned with dyeing of silk fabric using extract obtained from safflower (Carthamus tinctorius L.) which was microwave irradiated for 1–5 min. To make dyeing process more ecofriendly, bio-mordants and chemical mordants have been employed at optimal conditions. It is found that microwave treatment to the extract for 3 min is suitable to get darker shades with acceptable color characteristics using un-irradiated silk. It has been found that dyeing of un-irradiated silk fabric for 60 min using acidic extract of Safflower (pH 2) has given high color strength. Rating of colorfastness reveals that 7% of curcumin and lawsone as bio-mordant has not only given high color depth but also rated excellent fastness properties as compared to chemical mordants used. It is found that microwave treatment has not only improved the dyeing behavior of carthamin but also enhanced the color characteristics.

Microwave-assisted sustainable dyeing of wool fabric using cochineal-based carminic acid as natural colorant

ABSTRACTThe revival of natural dyes in textiles is gaining popularity due to their sustainable nature. The current study has been undertaken to improve the dyeing behaviors of cochineal-based natural dye (carminic acid) for wool dyeing under the influence of microwave treatment. For the purpose, wool fabric and extract obtained from cochineal insects (Dactylopius coccus costa) were irradiated for 1–6 min. The nature of dye bath (pH) and dyeing temperature were optimized using optimal irradiation conditions. To make dyeing process more sustainable and eco-friendly, bio-mordants and chemical mordants have been employed at optimal conditions. It is found that microwave treatment of extraction for 5 min is suitable to get darker shades with acceptable color characteristics using unirradiated wool fabric. K/S was found using acidic dye bath of cochineal insect of pH 1 for dyeing unirradiated fabric at 70°C using acidic extract of Cochineal bugs. Suggested ISO standards for color fastness revealed that 5% of henna and 3% pomegranate as bio-mordant have not only given high color depth but also rated excellent fastness properties as compared to chemical mordants used. It is found that MW treatment has not only improved the dyeing behavior of carminic acid but also enhanced the color characteristics.

Bio-coloration of bacterial cellulose assisted by immobilized laccase

In this work a process for the bio-coloration of bacterial cellulose (BC) membranes was developed. Laccase from Myceliophthora thermophila was immobilized onto BC membranes and retained up to 88% of residual activity after immobilization. Four compounds belonging to the flavonoids family were chosen to test the in situ polymerase activity of immobilized laccase. All the flavonoids were successfully polymerized by laccase giving rise to yellow, orange and dark brown oligomers which conferred color to the BC support. The optimal bio-coloration conditions were studied for two of the tested flavonoids, catechol and catechin, by varying the concentration and time of incubation. High color depth and resistance to washing were obtained for both compounds. The highly porous bacterial cellulose material demonstrated great performance as a bio-coloration support, in contrast to other materials cited in literature, like cotton or wool. The process developed is presented as an environmentally friendly alternative for bacterial cellulose bio-coloration and will contribute deeply for the development of new fashionable products within this material.

Effect of glass transition temperatures and zeta potentials of cationic copolymer latexes on pigment dyeing

Cotton fabrics treated by cationic copolymers show better wet rubbing fastness and handle than the conventional anion binders. However, the effect of glass transition temperatures and zeta potentials of cationic copolymer latex on pigment dyeing has not been reported. In the present study, three different kinds of p(St-co-BA) cationic latexes were synthesized by emulsion copolymerization. The prepared cationic copolymer latexes were all uniform spherical particles as shown by the TEM images. The glass transition temperatures and zeta potentials of the three kinds of latexes were -3.3 °C and 58.5 mV for St:BA=7:13, 13.4 °C and 65.9 mV for St:BA=9:11, 18.1 °C and 61.3 mV for St:BA=11:9. Cotton fabrics treated with 2.0 % cationic latexes produced ideal pigment dyeing performance. Comparing the color results, the latex (St:BA=9:11) had the highest color depth, the latex (St:BA=11:9) took the second place, while the latex (St:BA=7:13) gave the lightest color. The pigment dyeing performance of the latex is closely related to the zeta potential and the glass transition temperature.

Surface functionalization of polyamide fiber via dopamine polymerization

The oxidative polymerization of dopamine for the functional surface modification of textile fibers has drawn great attention. In this work, the functionalization of polyamide fiber via dopamine polymerization was studied with the aim of the fabrication of hydrophilic and antistatic surface. The conditions of dopamine application were first discussed in the absence of specific oxidants in terms of the apparent color depth of polyamide fiber. Dopamine concentration, pH and time were found to exert great impact on color depth. The highest color depth was achieved at pH 8.5. In the process of modification, polydopamine was deposited onto the surface of polyamide fiber. The modified polyamide fiber displayed a yellowish brown color with excellent wash and light color fastness, and exhibited good hydrophilic, UV protection and antistatic effects. A disadvantage of the present approach was the slow rate of dopamine polymerization and functionalization.

A quick display characterization method within local and limited input ranges of high color depth display systems for vision experiments

A quick display characterization method within local and limited input ranges of high color depth display systems for vision experiments

An Algorithmic Approach towards Chest X-Ray Image Enhancement by Global Histogram Equalization

In medical imaging, the scope of image enhancement is highly challenging. Here digital chest x –ray image are taken in a spatial domain and enhancement of the image is done through histogram equalization method. Histogram equalization is a specific case of the more general class of histogram methods. Histogram Equalization works the best when applied to images with much higher color depth like continuos data or 16 bit gray scale images. In particular, the method can lead to better views of bone structure in X-ray images that are either over or under exposed. An algorithm is proposed to enhance the chest x-ray images using Global Histogram Equalization.

Dyeing wet blue goat nappa skin with a microbial colorant obtained from Penicillium minioluteum

A colorant from Penicillium minioluteum behaving like an acid dye was identified, extracted, purified, and characterized. It was used for dyeing wet blue goat nappa skin at different pH, time, and temperature to standardize these parameters. Highest color depth and percentage dye exhaustion was achieved at pH 2.0 (altered after 30 min of dyeing), temperature 80 °C, and time 60 min. Study of dyeing mechanism revealed adsorption phenomenon similar to the Langmuir distribution. Interestingly, color diffusion was found to be uniform, faster, and attained equilibrium in a shorter span of time unlike conventional leather dyeing process. It was due to the presence of proteases; organic polyphenols; functional amphoteric auxiliaries; and alcohols and amines as per Fourier transform infrared spectroscopy in the colorant. Final sample dyed using standardized dyeing conditions showed good rub fastness and marked to moderate perspiration fastness. However, light fastness was found to be very poor. Furthermore, no change in tear and tensile strength was recorded in the dyed samples as compared to the undyed sample.

Characterization of dimethyl sulfoxide-treated wool and enhancement of reactive wool dyeing in non-aqueous medium

Wool pretreated with dimethyl sulfoxide (DMSO) was characterized and its dyeing behavior in non-aqueous green solvents was investigated. Reactive dyeing of wool in deep shades is challenging because the mandatory alkaline aftertreatment to match the fastness of mordant dyes inevitably causes damage to wool keratin. The current study showed that the colorfastness-integrity dilemma could be solved by replacing water with organic solvents as the dyeing medium. Covalent fixation is predominantly favored in solvent dyeing so that excellent colorfastness is achievable at any given shade without alkali aftertreatment. Compared with aqueous dyeing, solvent dyeing was found to give 30% higher covalent fixation on average, which translated to better colorfastness (0.5–1 grade) at higher color depth (Δ K/ S = 1.3–4.9). In addition, scanning electron microscopy, X-ray diffraction and attenuated total reflection-infrared spectroscopy results indicated that DMSO pretreatment induced morphological and structural changes of wool in favor of dyeability. The findings are crucial to the phasing-out of metal-containing dyes for eco-friendly wool dyeing.