Textiles, fluorescent dyes

Although many hydrocarbons exhibit fluorescence, often they are colourless and the fluorescence is only just into the blue, e.g. the linear terphenyl and quaterphenyl. Polycyclic ring systems such as terrylene and rubicene are used in analytical methods and OLEDs but a large number are ruled out of commercial use because of their potential to act as carcinogens. However, as mentioned in section 3.5.1.3, pery-lene is a useful fluorophore in a variety of outlets and pyrene is another polycyclic compound of interest. One derivative of pyrene (3.27) is a yellow-green fluorescent dye used in textile applications (Cl Solvent Green 7) and in analysis and sensors (see section 3.5.6.4). 

The main use of fluorescent dyes is in the coloration of synthetic fibres, especially polyester, polyamide and acrylics in conjunction with elastane fibres, for fashion, leisure and especially sportswear uses. The fluorescent textiles offer not only high design options but also a large degree of safety in use, for instance increasing the visibility of cyclists and runners in busy urban areas. 

Despite this early work, however, no real advance in the application of fluorescence to textiles was made until the twentieth century. Initial research conducted on fluorescent dyes by Lagono... 

R. M. Christie, Fluorescent dyes, in Handbook of Textile and Industrial Dyeing Principles, Processes and Types of Dyes, ed. M. Clark, Woodhead Publishing, Cambridge, 2011, vol 1, ch.l7. 

Bahners et al. [68] investigated the concepts of technical fibers for the special coated fibers to be used for textile solar collectors. The technical fiber made of different polymers (polymethyl methacrylate (PMMA) and polyethylene terepthalate (PET)) were characterized with respect to optical properties relevant for the model. The fibers were coated with a matrix of 5% polyvinyl acetate (PVA) in methanol, into which fluorescent dyes were dispersed. The wave guiding behaviors of the technical fiber over greater lengths were quantitatively analyzed by a logarithmic fit. The measured value was found to divert from the ideal fit at larger fiber lengths. 

K2CO3 (from KOH and CO2), used chiefly in high-quality decorative glassware, in optical lenses, colour TV lubes and fluorescent lamps il is also used in china ware, textile dyes and pigments. 

CE is also potentially a useful alternative analytical tool for monitoring of chemicals (dyes, flame retardants and lubricants) involved in various steps of the textile fibre manufacturing process. In this area, CE compares favourably with existing techniques. CZE-MSn was used for the analysis of sulfonated azo dyes [942]. A variety of fluorescent analytes including thiazole orange dyes have been characterised by CE-FLNS [943]. 

The initial objective of this series of books has been to establish a coherent body of explanatory information on the principles and application technology of relevance for students preparing to take the Associateship examinations of the Society. This particular book has been directed specifically to the subject areas covered by Section A of Paper B the organic chemistry and application of dyes and pigments and of the auxiliaries used with them in textile coloration processes. However, many qualified chemists and colourists interested in the properties of colorants and their auxiliaries have found the First Edition useful as a work of reference. For several reasons it has been convenient to divide the material into two separate volumes 1. Colorants, 2. Auxiliaries. Although fluorescent brighteners share some features in common with colorants, they have been treated as auxiliary products in this book. 

The phthalocyanines, naphthalocyanines, and certain of their metal derivatives (Figure 6.17) are infrared fluorophores. 61"64 As a class, they are exceptionally stable compounds, with copper (Cu) phthalocyanine (not a fluorophore) remaining intact above 300 °C in air. First used for textile dyeing in the last century and still widely used, there is a rich chemistry of phthalocyanines. Most derivatives can be made by prolonged heating of a phthalimide or phthalic acid derivative with a metal in powder or salt form at elevated temperature. Several derivatives absorb in the near-IR, and either fluoresce or phosphoresce. The electronic transitions of phthalocyanines are complex and have been extensively studied, at least in part because the symmetry of the molecule makes theoretical calculations of its spectroscopic behavior more tractable. Unsubstituted phthalocyanines and naphthalocyanines are, as a class, very insoluble in solvents other than, for instance, nitrobenzene. Sulfonated phthalocyanines are water soluble and exhibit spectra comparable to the parent derivative. Photolumines-cent phthalocyanines (Pcs) include SiPc, ZnPc, and PC itself. These compounds have been little used for practical infrared fluorometry to date however, Diatron Corpora-... 

These chromophores have declined significantly in importance as textile dyes bnt have remained of interest becanse of their fluorescent behaviour, as discussed in Chapter 3, section 3.5.1.5. One exception is the triphenodioxazine ring system, which is used to produce valuable blue dyes in the Direct (2.19) and Reactive dye classes (2.20) as well as pigments (see section 2.4.1.7). The dyes from this chromogen have a very high molar absorption coefficient (ca. 80 000) versus typical anthraquinone dyes (ca. 15 000) and have therefore replaced some of the dyes from this latter chromogen in the reactive dyeing of cotton. ... 

These classes of chemicals contain not only some of the oldest dyes, dating back to the 19th centnry, bnt also some of the most important flnorescent chromophores. The earliest of these discoveries was flnorescein (3.21), which was later brominated to give the polybromo derivative eosin (3.22) (Fignre 3.10). They are of little importance in textile coloration processes bnt are nsed in some fluorescent pigments and extensively in analysis and biological methods and also in tracing the course of water in drains and other water outlets. 

Many cationic dyes for acrylic fibres, especially methines, such as Cl Basic Red 13, Cl Basic Violet 7 and Cl Basic Red 74 are very bright and fluorescent and hence this fibre has a place in fluorescent textiles. 

Oxadiazole derivatives have been tested in the textile industry as antistatic agents for textile finishes,232,233 thermally stable polymers,82, 234,235 fluorescent whiteners,236 oil and water repellents on cotton and wool,237 and blue dyes for polyesters and polyamides.238 Oxadiazole merocyanine dyes have been patented as photosensitizers for silver halide emulsions.239... 

Materials such as pigments, iron stains and paint found on a textile may fluoresce. The presence of certain dyes can be determined based on their... 

Modification of the polymer or the presence of additives can effect the light resistance of a fiber. This is extremely important for textile conservation since fibers being produced currently by the man-made fiber industry may perform differently from those produced in earlier years. For example, a company bulletin, published first in 1960, reported that the resistance to chemical decomposition by fluorescent light or by sunlight of many of the nylons they manufactured had been improved (20). Titanium dioxide, which is used as a delustrant during the manufacture of fibers, can decrease their light resistance (13,15,18, 21, 22, 23). Dyes (18, 24, 25) and finishes (25, 26) are other important factors. 

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