Reactive dyeing of silk using commercial acid dyes based on a three‐component Mannich‐type reaction

Acid dyes are employed for commercially dyeing silk, which results in ionic bonds between the silk fibroin and the dye. This generally leads to low wet fastness properties for dyed silk fabrics. In this work, three commercial acid dyes with aromatic primary amine structures were selected to dye silk using a Mannich‐type reaction, resulting in improved wet fastness of dyed silk by forming covalent bonds between silk fibroin and dye. The Mannich‐type reactive dyeing was applied to silk fabrics at both 30 and 90°C in trials. Dyeing at 90°C can shorten the dyeing time compared with dyeing at 30°C, even although dye exhaustion and relative fixation at 90°C were a little lower. The dyeing process was optimised when the dyeing temperature was 90°C, dyebath pH 4, dye‐to‐formaldehyde ratio 1:30 and holding dyeing time 60 minutes. The results showed that the dye exhaustion on silk fabrics for the three aromatic primary amine‐containing acid dyes exceeded 94% and their relative fixation was over 80%. Their washing and rubbing fastness reached grade 4 or higher. Hence, the colour fastness properties of dyed silk fabrics using the Mannich‐type reactive dyeing method is superior to the conventional acid dyeing method using the same aromatic primary amine‐containing acid dyes. The Mannich‐type reactive dyeing for silk fabrics at 90°C can be developed into a novel and rapid reactive dyeing method, promising an effective dyeing process with excellent colour fastness.     

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.     

A water soluble cationic sulphur dye for the dyeing of silk

A water solubilised brown sulphur dye has been prepared by the reaction of Sulphur Brown 5G and 3-chloro-2-hydroxypropyltrimethylammonium chloride. The solubilised dye gave excellent fixation on silk, as high as 98.5%, representing a dramatic improvement on the parent sulphur dye when applied after reduction with sodium sulphide. Its light and rub fastness were satisfactory. The solubilisation of sulphur dyes using this technique is therefore promising for the dyeing of silk, without adverse effect on the substrate. Received: 16 March 2005; Accepted: 14 June 2005.     

Research in the cold pad–batch dyeing process for wool pretreated by hydrogen peroxide

The cold pad–batch dyeing process of wool pretreated by hydrogen peroxide was carried out with Lanasol reactive dyes and Realan reactive dyes. The influences of various conditions of the dyeing process, including urea dosage, sodium bisulphite dosage, pH value, batching time and the liquor pickup on colour yield, were analysed. Fixation, levelness of dyeing, dye penetration, colour fastness, breaking strength and elongation were compared between untreated and treated wool fabrics. The study showed that cold pad–batch dyeing of wool fabric is a good prospect for future use because of the resulting advantages, such as higher fixation yield, less energy usage and lower sewage discharge.     

活性染料用于拉细羊毛染色的研究

研究了四类活性染料染拉细羊毛的工艺条件和十二个染色配方。与媒介染料相比，用活性染料对拉细羊毛染色可获得更好的效果。染料的溶解度、匀染性、上色率、固色率均好于媒介染料，颜色的批差小。研究结果表明：除煮呢沾色牢度外，染色羊毛的各项牢度均优于媒介染料。     

Improving the environmental and economic aspects of cotton dyeing using a cationised cotton†

One approach to improve the affinity of anionic dyes for cotton is to add cationic dye sites to the fibre. The dyeing behaviour of cotton that had been rendered cationic by reaction with 2,3‐epoxypropyltrimethylammonium chloride was examined. Dye yields and fastness properties are reported for a number of direct, reactive and acid dyes with the modified fibre. Excellent dye yields and colour fastness properties were obtained without the use of electrolytes, multiple rinsings or fixation agents which are normally employed in cotton dyeing.     

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     

An innovative study on dyeing silk fabrics by modified phospholipid liposomes

Modified phospholipids from the commercial soybean lecithin were prepared via acetylation of the acetone insoluble fraction phosphatidylethanolamine. N‐Acetyl‐phosphatidylethanolamine was used to prepare liposomes for encapsulating anionic dyes (acid and reactive dyes) to be used in dyeing silk fabric. Size measurements of the liposomes showed that the maximum vesicle size was 36.61 nm for empty liposomes in comparison with 39.08 and 39.75 nm for acid dyes and 51.78 and 59.20 nm for reactive dyes. The efficiency of the micro‐encapsulated dyes to dye silk fabric has been investigated and compared with the conventional dyeing process using different parameters. It was confirmed that the acetylated acetone insoluble fraction liposome shows better encapsulation of the reactive dyes and achieves more dye uptake than the acid dyes. It was also found that fastness properties of dyed silk with micro‐encapsulated anionic dyes did not change significantly more than the conventional dyeing method. Reuse of the micro‐encapsulated dyebath produces low water pollution as the effluent is virtually colourless. As a result, the process is also economic and eco‐friendly.     

Synthesis and salt‐free dyeing characteristics of cationic reactive dyes containing polyetheramine segments

A series of cationic reactive dyes containing both quaternary ammonium and polyetheramine as soluble groups and monochlorotriazine as a reactive group have been synthesised and applied to cellulose fibre by salt‐free exhaust dyeing. Investigation of the synthesis method and dyeing properties of these cationic reactive dyes showed that the best pH value for these dyes is 6, and also that these cationic reactive dyes give a high substantivity to cellulose. In the salt‐free dyeing process, their adsorption was consistent with the Langmuir isotherm during the primary exhaustion stage, but in the secondary exhaustion stage the adsorption was in accordance with the Freundlich isotherm, and their secondary exhaustion reached up to 96% and above. Moreover, the degree of fixation, the levelling, and the transfer properties on cotton fabric were good. Light fastness reached grade 5–6, washing, perspiration, and dry rubbing fastness reached grade 4 and above, but wet rubbing fastness reached only grade 3–4.     

再生蚕丝蛋白纤维的染色性能研究

主要研究染料种类、染料质量分数、氯化钠质量浓度、染色时间、染色温度等5个因素对再生蚕丝蛋白纤维上染率的影响,分析了再生蚕丝蛋白纤维的染色性能.结果表明:对纤维素纤维染色性能较好的染料对再生蚕丝蛋白纤维也有很好的染色性能.运用直接染料对再生蚕丝蛋白纤维进行染色,得到的最佳工艺为:染料质量分数1％ (omf)、氯化钠质量浓度12 g/L、染色温度85℃、染色时间50 min.     

The effect of polyhydroxyurethane on dyeing of cellulosic fabrics with direct and reactive dyes

Dye yields and fastness properties are reported for direct and reactive dyes using a modified dyeing solution with polyhydroxyurethane. Excellent dye yields and colour fastness properties were obtained without the use of electrolytes, multiple rinsing or fixation agents, which are normally employed in cotton dyeing. From the results, it was found that polyhydroxyurethane media exhibit better dyeability and fastness than the normal aqueous media. Dye adsorption in polyhydroxyurethane media was much higher than in other aqueous systems. The dyed samples showed good hot pressing and washing colour fastness properties within the color change range. The excellent solubility of these dyes in the polyhydroxyurethane aqueous solution makes them ideal for use in exhaustion dyeing.     

Telechelic PEG-polymers end-capped with chromophores: Using as cationic reactive dyes and salt-free dyeing properties on cotton fabrics

In this article, telechelic polymers containing polyethylene glycol (PEG) moieties as space groups were combined with chromophores to synthesize cationic reactive dyes (BCD-R, BCD-Y, and BCD-B). The salt-free dyeing performance of these telechelic polymeric cationic reactive dyes on cotton fabrics was evaluated. The exhaustion and fixation of the dyes in salt-free dyeing was above 89.33 and 77.22%, respectively. The color fastness of dry rubbing for the three dyes reached grade 4–5, and their color fastness to light reached grade 5–6. Their washing fastness also reached grade 4–5, except for that of BCD-Y (grade 3–4). The results showed that the dyes possessed good leveling and build-up properties and substantivity to cellulose fiber. The zeta potential (ξ-potential) of dyed fabric was estimated, and it was found that the ξ-potential of the fabrics increased after dying with telechelic polymeric cationic reactive dyes, and the more dye that was used, the greater ξ-potential increase. The exhaustion curves of dyes were also determined, and they were much different from those of anionic reactive dyes. The adsorption kinetics and isotherms of BCD-R were investigated. It was found that the pseudo-second-order kinetic model gave the best fit of the experimental data at all three tested dyeing temperatures (25, 45, and 65°C) with R² values over 0.998. Both the Langmuir and Freundlich models could be used to describe the adsorption of BCD-R onto cellulose fibers and the Langmuir model fit the experimental data better than the Freundlich model. The thermodynamic parameters (ΔG, ΔS, ΔH, and activation energy) of the dye adsorption process were researched further. The results indicated that the adsorption of BCD-R onto cotton fibers was spontaneous and exothermic and that after adsorption onto the cotton fibers, the degree of freedom of the dye decreased.     

降解壳聚糖在棉织物活性染料低盐染色中的应用

采用降解壳聚糖对棉织物进行预处理,比较处理前后棉织物活性染料染色的上染率、固色率及耐摩擦牢度,在此基础上研究低盐工艺对棉织物活性染料染色的上染率、固色率的影响。实验结果表明降解壳聚糖预处理棉织物显著改善活性染料染色性能,提高染料上染率,减少了染整加工过程中对环境造成的污染。降解壳聚糖预处理的最佳工艺条件:浸渍温度80℃、降解壳聚糖用量0.8%(owf)、浸渍时间30 min。     

Dye behavior of cationically treated silk

To increase the performance of silk fabrics, especially their dyeability, a cationic modifying agent, 3‐(trimethoxysilyl) propyl dodecyl dimethyl ammonium chloride (HSQA), was prepared in our laboratory. The dye behavior of the cationized silk was examined with five leveling‐type acid dyes. Better color shades and good washing fastness were achieved after silk was cationized by HSQA, and it was possible to dye silk under neutral conditions at 70°C. The equilibrium adsorption isotherm and kinetic properties of the cationized silk dyed with CI Acid Orange 7 were investigated. The adsorption of CI Acid Orange 7 onto the HSQA‐cationized silk was also in good agreement with the Langmuir isotherm, with an enthalpy and an entropy of −20.13 kJ/mol and −30.06 J/mol K respectively. A pseudo‐second‐order kinetic model agreed well with the dynamic behaviors for the adsorption of CI Acid Orange 7 onto the cationized silk under neutral conditions, with the activation energy decreasing from 61.87 to 53.32 kJ/mol. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

活性染料及其真丝绸印染工艺探讨

研究了活性染料对丝绸进行染色和印花的工艺，提高了丝绸染色产品的色牢度、染深性、得色量和提升力。优选了酸浴法、中性浴法和碱浴法染色工艺条件以及印花工艺条件。指出一氟三嗪活性基优于一氯三嗪活性基，双活性基优于单活性基。国产活性染料应在溶解度、配套助剂、染料筛选等应用方面要加强研究。     

Innovation and application of dyes with high fixation

Reactive dyes are the main species for cotton dyeing due to their wide range of hue, satisfactory color fastness and facile application method. Aiming at increasing fixation on cotton fibers, benzimidazolone yellow reactive dyes, sulfonamide red reactive dyes and anthraquinone azo blue reactive dyes are designed. The preparation, characterization and application properties of these dyes with high fixation are introduced in detail. In order to achieve dye fixation to near 100%, macromolecular cro...     

Deep‐coloured polyester/cotton blends with low concentrations of polymethylol dyes by a one‐pass continuous dyeing process

An obvious limitation of the one‐pass continuous dyeing process for polyester/cotton blends is its inability to achieve deep colour depth, which is caused by the low dye fixation yields of commercial reactive dyes. In this study, the performances of polyester/cotton blends dyed with high‐fixation polymethylol dyes and disperse dyes were compared with those of polyester/cotton blends dyed with a mixture of reactive dyes and disperse dyes. Polymethylol dyes were observed to be suitable for dyeing polyester/cotton blends when used in low concentrations; the required concentrations of polymethylol dyes were only 23–58% of the concentrations of commercial reactive dyes required to reach a given colour level on polyester/cotton blends. The wash and crocking fastness of polyester/cotton blends dyed with polymethylol dyes were similar to those of polyester/cotton blends dyed with reactive dyes.     

Dyeing of N-modified viscose rayon fibres with reactive dyes

Modified viscose rayon fibres were produced by incorporation of different doses of a polydiallyldimethylammonium chloride based additive in the viscose dope prior to spinning. On dyeing the modified fibres with different reactive dyes, excellent dye exhaustion and total dye fixation above 90% were obtained without the use of electrolyte and with low salt concentration. Exhaustion and total dye fixation showed an exponential relationship. The wash fastness properties of the dyed fibres were excellent and the light fastness showed a slight drop in the modified fibres. The presence of the amino groups along with low density and crystallinity of the modified fibres may be responsible for the enhanced dyeability.     

A study of novel bisazo reactive red dyes with good wet fastness

Three series of bisazo reactive red dyes were synthesised using 6‐amino‐1‐naphthol‐3‐sulphonic acid and its derivatives as the coupling components. The dyeing parameters and wash fastness of these dyes on knitted cotton were evaluated and the relationships between the structure and dyeing properties were investigated. It was found that the hydrophilic groups introduced into the dye molecules decrease the substantivity and fixation of the dyes, but increase the build‐up and migration properties. The defined wash‐off factor can directly reflect the wash fastness of the dyes and the build‐up property can be improved by commercialisation using certain auxiliaries. The results indicate that there is the possibility of synthesising a red reactive dye with a satisfying balance between high fixation and good wash fastness and several such dyes have been developed.     

Synthesis and application to cellulose of reactive dye precursor of anti‐bacterial N‐halamine

To achieve textile dyeing and functional finishing in one process, a bleach‐resistant reactive dye precursor to anti‐bacterial N‐halamine was synthesised by reacting a type of dichlorotriazine reactive dye with 4‐amino‐2,2,6,6‐tetramethylpiperidine. The synthesised compound, which can be transformed to an N‐halamine molecule by exposure to dilute bleach solution, was used to dye cotton fabrics. After exposure to a dilute sodium hypochlorite solution, dyed cotton fabrics showed excellent anti‐bacterial properties against Staphylococcus aureus and Escherichia coli O157:H7, facilitating a ca. 6‐log reduction in bacteria within a short period of contact. Compared with the dichlorotriazine reactive dye, the reactive dye precursor demonstrated comparable dyeing properties including exhaustion and fixation values. No differences in rub fastness, wash fastness or bleach fastness were detected between fabrics dyed with, respectively, dichlorotriazine reactive dye and the reactive dye precursor to N‐halamine.