Pretreatment of cotton with poly(vinylamine chloride) for salt-free dyeing with reactive dyes

Poly(vinylamine chloride) has been investigated as a pretreatment for the salt-free dyeing of cotton with reactive dyes. Dye fixation was found to be much higher than by conventional dyeing without pretreatment, even in the presence of a large amount of salt. The influence of pretreatment conditions on dye fixation, such as pad–bake variables and the concentration of poly(vinylamine chloride), has been studied. The dyeing behaviour of CI Reactive Red 2 on pretreated cotton was examined and found to follow a Langmuir-type adsorption curve. Dyed cotton pretreated with poly(vinylamine chloride) showed excellent wash fastness and good rub fastness. It is concluded that poly(vinylamine chloride) is effective as a pretreatment for salt-free dyeing with reactive dyes.     

Application of polycarboxylic acid sodium salt in the dyeing of cotton fabric with reactive dyes

In this study, the effects of polycarboxylic acid sodium salt on the dyeing of cotton with reactive dyes were evaluated by measuring and comparing the K/S values and dyeing fastnesses of the dyed cotton fabric samples. Results showed that the K/S value and dyeing fastness of cotton fabrics dyed with polycarboxylic acid sodium salt, substituting inorganic salts as exhausting agent were close to that of with sodium chloride when dip‐dyeing process was used. While, in pad‐dry dyeing, the K/S value of cotton fabric samples dyed with polyacid salts as exhausting agent was higher than that of with sodium sulfate, and the dyeing fastnesses of these samples were nearly the same. The dyeing mechanism of cotton fabric with reactive dye, using polycarboxylic acid sodium salt as exhausting agent was analyzed. The dyeing exhausting mechanism of reactive dye seems different when the inorganic salt and polycarboxylic acid sodium salt were used as exhausting agent in the dyeing of cotton fabric with reactive dye. The polycarboxylic acid sodium salt, as weak electrolyte, increased the dye‐uptake of reactive dye on cotton fabric not only by screening negative charges on cotton surface, but also by the effect of salting‐out or hydrophobic combination. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Possibilities of polymer‐aided dyeing of cotton fabric with reactive dyes at neutral pH

Water‐soluble polymers have versatile application, viz., water‐soluble polyacrylates have been widely used in the reactive dyeing of cellulosic fibers and the related soaping as an important component of the leveling and washing agent. In this article, one such water‐soluble polymer, polyacrylic acid has been synthesized, characterized, and applied in conjunction with various types of reactive dyes, namely triazinyl, vinyl sulfone, high exhaustion, and bifunctional reactive dyes, along with crosslinking agents, namely glycerol 1,3‐dichlorohydrin and hexamethylene tetramine‐hydroquinone, respectively. One of the crosslinking agents (the former one) has been synthesized in the laboratory. Crosslinking agent is necessary to adhere the dye molecule onto the cellulose macromolecule. Different process sequences have been formulated and explored for dyeing purpose. All such dyeings were carried out at neutral pH. The dyed samples were assessed through color strength in terms of K/S values and their fastness properties were assessed by standard methods. All such dyeings were compared with conventional dyed samples. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Synthesis of reactive disperse dyes containing halogenated acetamide group for dyeing cotton fabric in supercritical carbon dioxide

A series of reactive disperse dyes incorporating halogenated acetamide group were synthesized and applied to dye cotton fabric in supercritical carbon dioxide (scCO₂). Dyeing experiments were conducted in scCO₂ with dye concentration of 0.5% owf (% on weight of cotton fabric), varying from 80 to 120 °C, for 1–3 h at a constant pressure of 200 bar. The results showed that the color strength of dyed cotton fabric increased favorably when increasing temperature and time. The color characteristics were studied as well in terms of the reflectance spectra. And the color fastness to washing and rubbing were also reasonably good.     

Dispersant‐free dyeing of poly(lactic acid) fabric with temporarily solubilised disperse dyes from azopyridone derivatives

Poly(lactic acid) fibre is derived from annually renewable crops and known to be 100% compostable. In order to extend its environmental friendliness into the dyeing process, dispersant‐free dyeing of poly(lactic acid) fabric with three temporarily solubilised azo disperse dyes based on hydroxypyridone moiety containing a β‐sulphatoethylsulphonyl group was investigated. The dyes were successfully applied to poly(lactic acid) fabric without the use of dispersants. The colour yields of the dyes on poly(lactic acid) fabric were observed to be dependent on dyebath pH and dyeing temperature. The optimum results were obtained at pH 4–5 and 110 °C. One of the dyes showed a colour yield as good as that of a commercial disperse dye and good build‐up on poly(lactic acid) fabric. All of the dyes could be alkali cleared owing to ionisation of the dye under mild alkaline conditions. Wash fastness was good to very good, and light fastness was good. The chemical oxygen demand levels of the poly(lactic acid) dyeing effluent from the dyes were considerably lower than those from a commercial disperse dye.     

A method for determining boron in cotton fabric

A technique involving radiofrequency-discharged oxygen has been demonstrated in the analysis for boron in cotton fabric as well as preparation of residual ash replicas of identical three-dimensional configuration of the original sample for microscopic studies. The main advantages of this technique lie in its simplicity and fastness.     

Non‐aqueous dyeing of cotton fibre with reactive dyes: A review

This study reviews the evolution of and recent developments in non‐aqueous reactive dyeing systems for cotton fibre. As conventional water‐based reactive dyeing causes adverse effects to the environment because of the need for huge quantities of water and chemicals, as well as generating a substantial amount of effluents, one of the alternative ways to alleviate pressure on the environment is to switch the dyeing medium from an aqueous water‐based approach to a non‐aqueous solvent‐assisted approach. Among a wide variety of non‐aqueous dyeing methods, this review focuses on several non‐aqueous dyeing systems, including dyeing textile fibres with chlorinated solvents, dyeing cotton with the use of reverse micellar systems, a dye/solvent suspension system and a non‐nucleophilic solvent‐assisted dyeing system.     

Pretreatment of cotton fabrics with polyamino carboxylic acids for salt‐free dyeing of cotton with reactive dyes

In this study, polyamino carboxylic acids have been used to improve the dyeability of cotton in a salt‐free reactive dyeing process. These polyamino carboxylic acids were prepared by partial carboxylation of polyvinylamine. Cotton fabric was pretreated with polyamino carboxylic acids and dyed with reactive dyes. The colour strengths of the dyed fabrics were evaluated by measuring the K/S values. The fastness properties (washing, rubbing and light fastness) of the dyed cotton fabrics were also measured. The pretreatment of cotton with polyamino carboxylic acids creates positive charges on the fabric surface. In this way, salt‐free reactive dyeing of cotton or dyeing with only a small amount of electrolyte is possible.     

Extraction of natural dyes from Alpinia blepharocalyx K. Schum. for dyeing of silk fabric

Natural dyes were extracted from the leaves and stems of Alpinia blepharocalyx K. Schum. Analysis of the designed experiment revealed that extraction at a plant/water ratio of 1:20 could reach an optimal production of natural dyes when extraction was performed at 80 °C, for 4 h, under 20 min ultrasound, in the presence of 10 g/l sodium hydroxide, and with two extractions. The extracted natural dyes were applied to the dyeing of silk fabrics using different methods, including or excluding a mordant. It was found that mordants had a significant effect on the colour of dyed silk fabrics. The silk fabric dyed with the pre‐mordant method using potassium aluminium sulphate as a mordant showed a bright yellow with a higher colour strength. The optimal dyeing conditions were reached when the extracted natural dyes were pre‐mordanted with 10 g/l potassium aluminium sulphate at pH 6, and for a 20 min dyeing time.     

One-bath dyeing of a polyester/cotton blend with reactive disperse dyes from 2-hydroxypyrid-6-one derivatives

A series of temporarily solubilised reactive disperse dyes based on 1-substituted derivatives of 2-hydroxypyrid-6-one were applied to a 65;35 polyester/cotton blend using a one-bath dyeing method without dispersing agent. The dyeing behaviour of these dyes on polyester and cotton fabrics, and polyester/cotton blend fabric, were studied. The colour yields of the dyes on the polyester/cotton blend were found to be highly dependent on the initial pH, optimum results being obtained at pH 5. Good levelling and good to excellent fastness properties were obtained on the blend, with the exception of lightfastness, which was moderate.     

One-bath dyeing of poly(ethylene terephthalate)/cotton blends with alkali-clearable azo disperse dyes containing a fluorosulphonyl group

Monoazo disperse dyes containing a fluorosulphonyl group, based on 4-amino-4'-fluorosulphonylazobenzene derivatives, were dyed on poly(ethylene terephthalate)/cotton blends and their dyeing and fastness properties investigated. A one-bath dyeing method was used, as these dyes can be alkali cleared in the same bath. In particular, the cross-staining of cotton was studied in order to assess their suitability for the one-bath dyeing of poly(ethylene terephthalate)/cotton blends.     

Optimising the anionisation of cotton with 3-chloro-2-hydroxy-1-propanesulphonic acid sodium salt for dyeing with basic dyes

To enable the dyeing of cotton with basic dyes, cotton fabrics were anionised using 3-chloro-2-hydroxy-1-propanesulphonic acid sodium salt (CHPSAS). The anionisation efficiency of three typical textile processing application methods has been investigated, including cold pad-batch, pad-dry-cure, and pad-steam. To obtain the highest CHPSAS anionisation efficiency and dye uptake with basic dyes, the influence of CHPSAS concentration as well as molar ratio between CHPSAS and NaOH was evaluated. Additionally, various kinds of basic dye were applied to examine further the dyeability of the anionised cotton.     

A novel method for vinyl grafting onto cotton fabric using ceric-cellulose thiocarbonate redox system

Treatment of cotton fabric with carbon disulphide in presence of NaOH resulted in cellulose thiocarbonate. The latter formed a complex when treated with ceric ammonium nitrate (CAN). After being thoroughly washed, the Ce^IV cellulose thiocarbonate was capable of initiating vinyl graft polymerization onto cotton fabric without homopolymer formation. The graft yield obtained with methyl methacrylate was found to increase by increasing CAN from zero to 50 mmol/l at temperatures from 60 to 80°C. Grafting was greatly favoured at pH 2; alkaline pH offset grafting. Incorporation of up to 7% of methanol, ethanol, or isopropanol in the aqueous polymerization medium enhanced grafting significantly with the certainty that the highest graft yield was obtained with isopropanol; using higher alcohol percentages decreased grafting. The rate of grafting showed an initial fast rate followed by a slower rate; 60 minutes reaction time proved appropriate for grafting irrespective of the condition used. In addition to methyl methacrylate the ability of Ce^IV-cellulose thiocarbonate to induce grafting of acrylonitrile and acrylamide was also examined. The rate of grafting followed the order methyl methacrylate > acrylonitrile > acrylamide.     

Microwave‐assisted dyeing of poly(butylene terephthalate) fabrics with disperse dyes

In this study, conventional heating and microwave dielectric heating in the exhaust dyeing of poly(butylene terephtalate) fabrics with disperse dyes were studied in order to determine whether microwave heating could be used to increase the dyeability of poly(butylene terephtalate) fibre in shorter processing times and enable dyeings of adequate wet fastness to be obtained. Accordingly, the samples of 100% poly(butylene terephtalate) single jersey knitted fabric were dyed with CI Disperse Yellow 160 and CI Disperse Yellow 42, CI Disperse Red 177 and CI Disperse Red 91, CI Disperse Blue 79:1 and CI Disperse Blue 54 at 98 °C with or without microwave dielectric heating. The colouristic properties, colour fastnesses and the tensile properties of the dyed fabrics were investigated and compared with each other. Microwave dielectric heating is regarded as a tool for ‘green chemistry’ and provides many advantages over conventional heating without any deterioration in the properties of the dyed materials. Microwave heat dyeing enhances the exhaustion and the fixation of dye, and good colour fastnesses and repeatability in dyeings are achieved in short heating times of the dyebath.     

Low‐temperature carrier dyeing of poly(vinyl chloride) fibers with disperse dyes

The effects of various carriers on the color yield of poly(vinyl chloride) (PVC) filaments in a disperse dyeing system were investigated. The dyeability of disperse dyes on PVC fiber was improved using appropriate carriers. The enhancement of dye uptake imparted by carriers coincided with the reduction in glass‐transition temperature, which in turn coincided approximately with the similarity of the inorganic/organic ratio values between PVC fibers and carriers. The results clearly demonstrate that hydrophobic carriers function as diluents of PVC fiber, facilitating dye diffusion by increasing segmental mobility of the fiber. The dyed PVC filaments with disperse dyes showed reasonable levels of build‐up and color fastness properties in the carrier‐assisted dyeing. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 3896–3904, 2003     

Pretreating poly(p‐phenylene benzobisoxazole) fibre with polyphosphoric acid and dyeing with disperse dyes

In recent years, many advanced composite materials based on poly(p‐phenylene‐2,6‐benzobisoxazole) fibres have become prominent in applications requiring high‐strength and flame‐retardance such as body armour, industrial reinforcement materials and military camouflage. However, the application of these fibres used as protective clothing is limited due to difficulties in dyeing and printing. In the present work, a process for pretreating poly(p‐phenylene benzobisoxazole) fibre with polyphosphoric acid was applied, and the pretreated fibre was then dyed with disperse dyes via dip dyeing. Effects of pretreatment temperature and time on structure and properties were investigated. Surface morphology, crystallinity, chemical structure and degree of orientation of fibres were characterised. The results indicated that the supramolecular structure of the fibre was relaxed or swelled by polyphosphoric acid in the pretreatment process, so that the dyeability of poly(p‐phenylene benzobisoxazole) fibre was improved, with satisfactory dye exhaustion, K/S values and dyeing fastness. Also, with the appropriate pretreatment process, the swelling effect of polyphosphoric acid on the structure of poly(p‐phenylene benzobisoxazole) fibre was limited, so as to control the decrease in tensile strength and limiting oxygen index of the dyed fibre.     

Dyeing of cotton with the natural dye extracted from waste leaves of green tea (Camellia sinensis var. assamica)

Due to an increase in the production of green tea, the amount of leaf waste has increased enormously, causing serious environmental problems. With regard to environmental awareness, the possibility of reusing the waste leaves of green tea as a low‐cost and abundantly available source of natural dye for dyeing cotton fibres was investigated. Natural dye powder from the waste leaves of green tea (NDPT) was successfully applied to dye cotton fibres without mordant by batch experiments. NDPT was obtained as a dark brown powder with a yield of 2.7 ± 0.5% w/w from dried waste leaves of green tea. The optimal conditions for dyeing NDPT onto cotton fibres were: pH of dye solution, 3; material to liquor ratio, 100:1; dyeing time, 180 min; concentration of dye solution, 3.0 mg/ml; and dyeing temperature, 100 °C. The colour of cotton fibres dyed with NDPT was observed to be dark brown. The adsorption data of NDPT on cotton fibres was best fitted with a Langmuir adsorption isotherm model with a correlation coefficient (R²) of 0.997. It is clear that there is a strong possibility of reusing the waste leaves of green tea as a low‐cost and abundantly available source of natural dye for dyeing cotton fibres.     

Analysis of photofading of phenylazo-indole and phenylazo-N-ethanolaniline disperse dyes on poly(ethylene terephthalate) fabric using the PM5 method

The photofading behaviors of phenylazo-N-(ethanol)aniline and phenylazo-indole, nitrohetarylazo-N-substituted aniline disperse dyes on poly(ethylene terephthalate) (PET) substrate were analyzed using the Kubelka-Munk (K/S) parameters of the dyed fabrics exposed to a carbon arc in air. The initial experimental slopes (K_PET) of fading on PET were estimated from the time profiles of the K/S values at the λ_max. The rates (k_0,i) of reaction of these dyes with ¹O₂ were estimated by frontier orbital theory using the PM5 method. The photosensitivities (f_i) of the dyes were estimated from the K_PET assuming that the K_PET values are proportional to the product of k_0,i and f_i. Dyes with small f_i values, irrespective of their k_0,i values, possess excellent lightfastness (LF), while dyes with larger f_i values possess poorer LF. The validity of estimating k_0,i values by the MO method was confirmed experimentally by analyzing the mutually photosensitized fading behaviors of combination dyeings.     

桑葚果渣花色苷的低共熔溶剂提取与分离

以桑葚果渣为原料,在低共熔溶剂(DESs)中,经DESs提取与大孔树脂分离两步,回收了果渣中花色苷.测试了不同类型DESs与提取方法对花色苷提取率的影响,通过不同型号大孔树脂作为吸附载体对花色苷进行回收以脱除DESs.采用HPLC、HPLC-MS对花色苷进行定量与定性分析.结果表明,DESs中草酸-氯化胆碱〔n(草酸)...     

The dyeing of poly(lactic acid) fibres with disperse dyes using ultrasound: Part 2 - Fastness

The use of ultrasound imparted greater colour strength to 1% omf dyeings of five of six disperse dyes studied, both before and after reduction clearing and had no effect on either the colour or λ_max of the dyeings. The lower fastness obtained to both wet and dry rubbing as well as to the first two/three of the five repeated wash cycles was attributed to the greater colour strength of the dyeings imparted by the use of ultrasound during dyeing.