An analysis of the factors influencing unlevelness of a direct dye on a pilot-scale jet dyeing machine

The investigation used a pilot-scale jet dyeing machine to examine the relationship between the dye exhaustion rate per contact and dye unlevelness on the fabric. It was found that a commercially acceptable degree of unlevelness could be obtained for a direct dye on pure cotton fabric as long as the exhaustion rate did not exceed 1.0% per contact, independent of the dye amount used. Bath contacts and fabric contacts influenced unlevelness in equal manner. Non-ionic surfactants, which had been selected so as not to influence the dye exhaustion rate or its equilibrium uptake, appeared to have little or no influence on unlevelness. Control of the dye uptake by electrolyte addition proved to be a more efficient dyeing strategy than controlling it by dye addition, as unlevelness in the first case was much lower at the same exhaustion rate.     

Optimisation of the disperse dyeing process using dyebath analysis

A competitive market forces textile manufacturers to continuously look for ways to increase productivity and resource efficiency. Taking the exhaust dyeing of polyester with disperse dyes as an example, it is shown that detailed process analysis using, among other methods, dyebath monitoring can yield considerable benefits. In the case examined, process cycles for a typical trichromic set of dyes could be shortened by 13% and dye unlevelness on the substrate reduced by 45%. The study confirmed that for optimum performance, process profiles need to be machine-specific since the maximum temperature gradient that yielded commercially acceptable unlevelness varied significantly from one machine to another machine. Received: 4 April 2005; Accepted: 14 June 2005.     

Chemical engineering aspects of reactive dyeing

The process of dyeing with reactive dyes was formulated on the basis of diffusion of dye species in the pores of polymer phase accompanied by fixation reaction with fiber substrate on the pore wall incorporating hydrolysis of dye species. The effect of the hydrolysis on the fractional fixation was numerically analyzed under various levels of bath ratio and degree of mixing in the dyebath. The simulation model was presented to yield the unlevelness arisen from lack of uniformity of degree of mixing in the dyebath.     

Bulk–scale Dyeing of Acrylic Yarn Packages

Bulk–scale dyeing trials on three different types of acrylic fibre are described. Basic dyes were applied under conditions predicted to give a borderline degree of unlevelness, following earlier laboratory work [1–3] intended to determine the relative importance of different factors which control level dyeing in this system. The results of the dyeing trials are discussed in this context and an attempt is made to attribute the effects observed to specific causes of unlevel uptake of dye.     

Influence of Substrate Type on Level Dyeing of Acrylic Yarn Packages

In an earlier paper [1], the influence of flow rate, ramp (constant rate of temperature rise) and package density on the rates of dyeing of two basic dyes on Ex/an, and on the levelness obtained in the resulting dyeings, was investigated, and a relationship was derived to link these factors quantitatively. This work has now been extended to cover the behaviour of various basic dyes on Exlan and other acrylic fibres, under conditions expected to give borderline levelness. It has been shown that the shape of the rate–of–dyeing curve depends on the type of acrylic fibre and, to a lesser extent, on the cationic retarder used, but not on dye type within the group of CV2. 5–3. 5 basic dyes examined. The response of dyeing rate and degree of unlevelness to deliberate variations of ramp, as demonstrated in the previous work on Exlan, is now confirmed on Cashmilon. Evidence of a different type of random unlevelness, not related directly to dyeing rate, was also obtained from dyeings on the various fibres at a slow ramp.     

Mechanistic investigations on the action of levelling agents in reactive wool dyeing

Although levelling agents for reactive dyes have been on the market for more than twenty years, there still remains some uncertainty as to their mode of action. Therefore an investigation has been carried out, using Albegal B as a typical levelling agent and reactive dyes from the Lanasol range. There are three mechanisms proposed to describe how auxiliaries such as Albegal B can act to overcome tip/root unlevelness when dyeing wool fibres: a dye complex mechanism, a surface mechanism and a fibre mechanism. These are discussed in the light of the experimental results.     

Dyeing machine control using in-line colour measurement. Part 3: Online dyeing quality control

A system is described that controls the dyeing process so as to produce a package within a final unlevelness tolerance in the minimum time. This is achieved by incorporating into the control algorithm a mathematical model capable of predicting the unlevelness in a dyed package from the current state of the system. The use of such a general strategy allows production of dyeings of acceptable quality in minimum time and requires little intervention from the machine operator.     

Levelness in the Dyeing of Wool Yarn and Fabric

In experiments with a thin bed of cloth, the maximum rate of uptake of dye by a wool yarn has been found to be limited by the concentration gradient of the dye across the yarn. A type of unlevelness observed in a conventional cross-wound package is attributed to the same concentration gradient.     

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.     

Waterless dyeing of polylactic acid with disperse dyes using decamethylcyclopentasiloxane as medium

Polylactic acid (PLA) fibre as a new generation of eco-friendly polyester fibre is expected to substitute polyethylene terephthalate (PET) fibre to be an important textile fibre raw material. However, there exist severe strength loss and light dyeing colour by the traditional water bath dyeing method, which seriously affect the promotion and application of PLA fibre in the textile fields. Therefore, it is necessary to study waterless dyeing method for PLA. Decamethylcyclopentasiloxane (D5) possesses excellent physical and chemical properties with the characteristics of odourless, non-flammable, and stable to various chemicals, which has been studied to be used as a waterless dyeing medium for PET fabric. In this study, D5 was selected as the medium to study the waterless dyeing process and properties for PLA. The effects of disperse dye dosage, dyeing temperature, dyeing time and liquor ratio on the dyeing properties of PLA fabric were investigated. The results showed that the optimal dyeing process conditions were as follows: the dye dosage was 4%, dyeing temperature and time were 120°C and 40 min, respectively, and the liquor ratio was 1:10. Then PLA was dyed by three different colour disperse dyes using the optimal process which were compared with the traditional water bath. The results showed that the properties of dyed PLA fabrics with D5 could reach the dyeing effect of the traditional water bath method, while causing less influence on its mechanical property. Therefore, this research proved that D5 can be used as a dyeing medium for PLA fabric to substitute the traditional water bath dyeing.     

Trends in the dyeing machinery manufacturing industryndashstrategy and dynamic response

An integrated model that incorporates both demand and supply elements has been used to analyse the attractiveness of the dyeing machinery manufacturing industry in the 1990s. Demand and supply interaction will ultimately influence the pattern of proliferation within the product life cycle of dyeing machinery. Kelvin Cheuk suggests that only by adopting a more dynamic strategy with quick response to changes can companies in this industry survive and grow. The approach of strategic alliance, taken by Fong's National Engineering, is discussed.     

蚕蛹蛋白纤维混纺纱染色效果影响因素分析

为迎合市场对蚕蛹蛋白纤维应用的需求,对蚕蛹蛋白纤维和天丝混纺纱进行了染色性能测试分析。以上染率及K/S值作为衡量指标,对上染后的蚕蛹蛋白纤维混纺纱进行上染效果评估。通过综合考虑,确定最佳染色工艺如下:1%(o.m.f.)的活性蓝M-2GE染料,浴比1∶20,平平加O质量浓度为0.5 g/L,硫酸钠质量浓度为25 g/L,碳酸钠质量浓度为15 g/L,上染温度和时间分别为65℃和45 min,固色温度和时间分别为70℃和35 min。经最优工艺染色后,蚕蛹蛋白纤维针织面料染色牢度较好,符合染色质量要求。     

Chemical Engineering Aspects of Dyeing Processes

Abstract

First, existing research on diffusion of disperse, reactive, and ionic dyes in polymers and correlation of the rate of dyeing to the operating variables in the dyebath is reviewed. Second, to discuss the kinetic aspects of various dyeing processes, the dyeing of textiles is classified into two categories: adsorptive and reactive dyeings, and these two dyeing processes are modeled in terms of diffusion of dyes in polymers accompanied by some physicochemical interaction with the polymer substrates. The process of adsorptive dyeing was formulated on the basis of a dual-mode sorption and mobility model where the porelike region was conveniently invoked. The calculated profiles of the concentration of immobilized dye are similar to the measurments of dye distribution curves by means of film-roll, microdensitometric, and microspectrophotometric techniques. The outline of formulation of the process of dyeing with reative dyes (i.e., reactive dyeing) is given on the basis of diffusion of dye within the fiber accompanied by a fixation reaction incorporating hydrolysis of dye species. It is concluded from numerical analysis that the lower the bath ratio, the less the decrease of the final fixation due to hydrolysis of the dye and the less the influence of mixing in the dyebath on the fixation. When the fixation reaction is slow, the final futation is almost independent of the bath ratio and the degree of mixing.     

PET／CGP共混纤维的制备与性能

采用易染聚酯(CGP)切片与PET切片按一定比例共混,造粒,纺丝得到150 dtex／36 f PET／CGP共混纤维,分析了共混纤维的染色性能和力学性能。结果表明:在常压沸染条件下,PET／CGP共混纤维的染色性能较PET纤维显著提高。随着CGP含量的增加,纤维上染率明显增加,但纤维的力学性能略有下降。当纤维中CGP质量分数为50％时,PET／CGP共混纤维的分散蓝2BLN上染率达92．73％,分散黄SE-4GL上染率达70．41％。     

A Method of Evaluating the Exhaustion of Disperse Dyebaths

Exhaustion of dyebaths when dyeing polyester fabric with disperse dyes can be evaluated by comparing two consecutive dyeings in the same bath either by visual assessments or by estimating the ratio of the dye concentrations of the two dyeings. Exhaustion ratings, related to the residual dye concentration in dyebath, are proposed.     

聚对苯二甲酸丙二酯纤维的染色性能

根据Shell公司和Dystar公司的研究,用Optidye系统从分散染料吸附与上染率、染色温度、pH值、匀染性及染色牢度等方面解析了聚对苯二甲酸丙二酯(PTT)纤维的染色性能。PTT纤维在100℃就可染到深色,在60～80℃和90～100℃有两个吸附速度较快区域;PTT纤维属易染型纤维,在最高温度染保持30～40min即可。高温型分散染料在120℃染色,常压100℃染色无需pH值调节。分散染料染色牢度(洗涤、摩擦及耐光)非常好。     

Determination of colour sensitivity of dye mixtures for disperse dyes

A method has been developed to quantify the colour sensitivity of a dye mixture. In this method, the concept of the colour sensitivity of matching recipes has been developed so that it covers variations, not only in dye concentrations, but also in dyeing parameters. Firstly, the 'individual colour sensitivity' of a dye mixture to a specific dyeing parameter was quantified by comparing the colour difference between the resulting shade from a normal dyeing condition and that produced by giving a change to the parameter. These resultant data were used to calculate the total colour sensitivity covering the factors, temperature, time and liquor ratio, with a model established based on CMC(2:1) equation. This calculated result simulates the reproducibility of a dye mixture in the dyeing application under certain accuracy of the dyeing process control. A set of dye recipes was applied by dyeing to verify the calculation with disperse dyes on polyester.     

Decolorization of disperse and reactive dye solutions using ferric chloride

The composition of wastewater from dyeing and textile processes is highly variable depending on the dyestuff type; typically it has a high chemical oxygen demand. This study examined the decolorization of some of the most commonly used disperse and reactive dyestuffs by destabilization using ferric chloride as a coagulant. Dye removal, distributions of zeta potential, concentration of suspended solids, changes of the SCOD/TCOD ratio and distributions of SV and SVI values were investigated in this work. Compared to reactive dyes, disperse dyes have lower solubility, higher suspended solids concentrations and lower SCOD/TCOD ratios. It was concluded that disperse dye solutions are more easily decolorized by chemical coagulation than reactive dye solutions.     

国产液体活性染料的开发和应用

该文介绍国产液体活性染料的开发和应用。它具有流动性和溶解度佳、适用于喷墨印花和小浴比（1：3）汽雾染色等印染工艺,大大减少印染厂的有色污水,节约能源（电或热能）,改善生产和印染车间劳动条件,方便加料计量自动化。它可以通过纳滤膜装置或物理法使染料脱盐,然后在染料液中选择性加入合适的助剂,如￡．已内酰胺等,非离子表面活性剂、分散剂、pH稳定剂和适量的水,搅拌1小时后,调节pH到4．5～6．5。获得的液体活性染料,在0～25℃可贮存3～6个月,不沉淀,不降低染料强度。     

Effect of microencapsulation on dyeing behaviors of disperse dyes without auxiliary solubilization

Microencapsulated disperse dye can be used to dye hydrophobic fabric in the absence of auxiliaries and without reduction clearing. However, little available information for dyeing practice is provided with respect to the effect of microencapsulation on the dyeing behaviors of disperse dyes. In this research, disperse dyes were microencapsulated under different conditions. The dyeing behaviors and dyeing kinetic parameters of microencapsulated disperse dye on PET fiber, e.g., dyeing curves, build up properties, equilibrium adsorption capacity C_∞, dyeing rate constant K, half dyeing time t_1/2, and diffusion coefficient D were investigated without auxiliary solubilization and compared with those of commercial disperse dyes with auxiliary solubilization. The results show that the dyeing behaviors of disperse dye are influenced greatly by microencapsulation. The diffusion of disperse dyes from microcapsule onto fibers can be adjusted by the reactivity of shell materials and mass ratios of core to shell. The disparity of diffusibility between two disperse dyes can be reduced by microencapsulation. In addition, the microencapsulation improves the utilization of disperse dyes due to no auxiliary solubilization. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011