Making the product fit for the job

Glover, Brian

doi:10.1111/j.1478-4408.1991.tb01331.x

Cited by 14 publications

(12 citation statements)

References 9 publications

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“…Colorants listed under the same CI generic name have the same chemical constitution as their essential colorants but may not have identical application, fastness, or toxicological profiles. It has been demonstrated that products with the same CI generic name do behave differently (11) and that not all preparations are manufactured to the same degree of purity or consistency of strength (12). Thus, two dyes with the same CI designation may not DYEINGbe immediately interchangeable.…”

Section: Naming and Classification Of Dyestuffsmentioning

confidence: 98%

Dyeing

Bide

2016

Kirk-Othmer Encyclopedia of Chemical Technology

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DYEINGFor those who see color, the world is a colorful place. Most humans have color vision and they enjoy and appreciate the wide palette of nature. We use colors to imitate nature, and to decorate our environment, our food, and ourselves. For most colors under human control, a colorant can be included when an item is formed (such as for an extruded plastic object) or combined in some medium that is applied to a surface (eg, paints and cosmetics). For clothing, furnishing, and in many other end-uses, textile materials are ubiquitous. The process of dyeing, in which a colorant penetrates the substrate, is used to color them. The same dyeing process is occasionally used to color paper and leather, and textiles can be colored by nondyeing means, but textiles and dyeing have a high degree of mutual inclusivity.The global consumption of textiles in 2012 was estimated at 83 million tonnes, of which 55 million tonnes was synthetic (including almost 40 million tonnes of polyester) and 23 million tonnes was cotton. Manufactured cellulosic and other natural fibers constituted the remaining 5 million tonnes (1). Fiber use has continued to increase at a rate faster than the growth of population. Dye is applied to these fibers at a rate of approximately 1-2%, ie, the annual production of synthetic dyes is approximately 1 million tonnes (2,3).Dyeing occurs when a soluble colorant is adsorbed at the surface of a fibrous substrate, and then diffuses into the substrate. What follows is a detailed examination of this basic process in both theoretical and practical terms. Dyes, Pigments, and FibersColorants are typically divided into dyes and pigments. The demarcation between them is primarily based on their solubility; a pigment relies on insolubility of the medium in which it is dispersed, while a dye requires some degree of solubility, maybe low or maybe temporary, that will allow it to diffuse into the polymeric matrix of a textile fiber. In order for a colored substance to be considered as a useful dyestuff, factors beyond solubility are required. A dyestuff must be substantive for a textile and thus be preferentially taken up by the fiber, usually from an aqueous solution. The uptake should be high enough to be economic, and the rate at which the dyeing occurs should be controllable to give a uniform level result. The dyed textile should have satisfactory fastness for the intended end use. The process of dyeing therefore combines chemistry, application technology, economics, and customer needs.1.1. Dyes: Natural vs Synthetic. Dyeing is an ancient practice. Originally, all dyes were of natural origin obtained locally from plants and even animals. Tyrian purple, obtained from a species of whelk, gave rise to the "purple of the emperors," its elevated status arising from the cost and effort involved in extracting useful quantities of colorant. As communication developed, dyes and dyed textiles were among the important items of trade, and technically superior natural dyes often supplanted local materials. Indigo from India and M...

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Section: Naming and Classification Of Dyestuffsmentioning

confidence: 98%

Dyeing

Bide

2016

Kirk-Othmer Encyclopedia of Chemical Technology

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“…The author did not have detailed information about the nature of the salt coming from diluents for the dyes examined. Generally, they may consist of buffers and neutral salt such as common salt and Glauber's salt [21]. Salt, in the form of caustic soda and sulphate from sulphuric acid, introduced to the dyebath by hydrolysation and neutralisation, varied between 0.044 and 0.44 g ⁄ dm 3 , and the adjustment of the pH value introduced 1.1 g ⁄ dm 3 salt in the form of caustic soda (0.6 g ⁄ dm 3 ) and sodium bicarbonate (0.5 g ⁄ dm 3 ).…”

Section: Influence Of Electrolyte Concentrationmentioning

confidence: 99%

An analysis of the substantivity of hydrolysed reactive dyes and its implication for rinsing processes

Ferus-Comelo¹

2012

Coloration Technology

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Substantivity plays a key role in dyeing processes, for dye exhaustion and fixation as well as for dye removal during rinsing. The latter is especially relevant for reactive dyes when the hydrolysed dye has to be removed from the fibre. The substantivity of the hydrolysed form of 46 commercially important reactive dyes was analysed at two temperatures for a wide range of dye amounts, pH values and electrolyte concentrations. The results showed that substantivity was highly dye-specific and varied, for each variable analysed, almost within the entire theoretically possible range of values. Substantivity values correlated best with the number of sulphatoethylsulphone groups in the dye molecule and dye solubility in the presence of sodium chloride. Sensitivity to electrolyte, pH, dye amount and temperature broadly correlated with each other, implying that a reduction in electrolyte concentration and an increase in pH and temperature are more beneficial in the removal of highly substantive reactive dyes. Some dyes remained highly substantive even at 90°C, indicating that dye removal in industrial processes, too, would be difficult. For dyes with little substantivity, however, wash baths at the boil do not appear to be necessary, neither is the significant removal of electrolyte before rinsing at elevated temperature.

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“…Within any application range of dyes, the same or compatible dyes, diluents and auxiliary agents are employed. Dye standardisation makes a major contribution to dye selection and the ability to achieve RFT dyeing [81,82,85]. Simple product substitution using so‐called equivalent dyes is thus not an option.…”

Section: Dye Standardisationmentioning

confidence: 99%

“…The dye user will obtain optimum reproducibility from a combination of dyes if they are robust, compatible, stable and consistent [17,123,124]. There are other reasons, of course, for arriving at a particular dye selection and these have been discussed elsewhere [81–83,123,124].…”

Section: Dye Evaluationmentioning

confidence: 99%

Significance of dye research and development for practical dyers

Park¹,

Shore²

2007

Coloration Technology

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The history of research and development on synthetic dyes stretches back for 150 years. Major contributions to practical dyeing have been the provision of dye ranges for both natural and synthetic fibres of a sufficiently wide colour gamut to obtain a multitude of colours. Dye standardisation, with the associated analytical, testing and evaluation methods, has ensured that products are fit for purpose. Ecotoxicology has been a major issue for several decades, adding to the cost of research but improving the health and safety aspects of dyes. Developments in physical forms of dyes have been designed to improve health, safety, hygiene, ease of handling and accuracy in dispensing. Application research, in conjunction with dye users and machinery makers, has been a long‐established feature of the industry. This has resulted in improved, controlled and systematic dye application techniques, leading to shorter dyeing cycles, right‐first‐time (RFT) processing and a reduction in processing costs. Although dye making is now based mainly in Asia, it is hoped that R&D efforts will continue to ensure that products of the necessary quality and performance remain available.

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Making the product fit for the job

Cited by 14 publications

References 9 publications

Dyeing

Dyeing

An analysis of the substantivity of hydrolysed reactive dyes and its implication for rinsing processes

Significance of dye research and development for practical dyers

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