Light-fastness

Further information can be found in standard methods such as EN ISO 11341 orASTMD4303. 

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The use of 2-aminothiazole derivatives as dyeing compounds is direct related to the development of synthetic fibers. Some typical examples are given in Table VI-14. The importance of these dyes lies in their performance on acetate fibers. They have excellent fastness to gas fumes, produce a bright blue shade, and have a high tinctorial strength. Their only disadvantage is their relatively low light fastness, which does limit their application. 

Although the cross-sectional shape of the spinneret hole direcdy affects the cross-sectional shape of the fiber, the shapes are not identical. Round holes produce filaments with an approximately round cross section, but with crenelated edges triangular holes produce filaments in the form of a "Y." Different cross sections are responsible for a variety of properties, eg, hand, luster, or cover, in the finished fabric. Some fibers may contain chemical additives to provide light-fastness and impart fire retardancy. These are usually added to the acetate solution before spinning,... 

Dioxazine Violet. Carba2ole Dioxa2ine Violet is prepared by the reaction of two moles of 2-ainino-A/-ethylcarba2ole with chloranil. This violet may be used in most plastics for shading phthalocyanine blues, because it has comparable light fastness. At relatively high temperatures, it may be subject to slow decomposition. 

Pyrazolone derivatives have found many applications as cotton azo dyes because, even if they were more expensive intermediates, they improved qualities such as brightness and light fastness. Rosanthrene Orange (727) and Pyrazol Orange (728) are two representative examples. 

Pigments for finishes are selected on the basis of their colour, but special attention must be paid to inertness in the chosen binder and stability and light fastness under the conditions of application and exposure. Flake pigments such as aluminium and micaceous iron oxide give finishes of lower moisture-vapour permeability than conventional pigments, and consequently contribute to better protection. 

Although it might seem at first sight that dyestuffs are merely held mechanically within the pores, and this view is probably correct in the case of inorganic pigments, there is some support for the opinion that only those dyestuffs which form aluminium/metal complexes produce really light-fast colorations. 

The finishes produced have very good light fastness and corrosion resistance, and, unlike integral colour finishes, the shade is largely independent of the aluminium alloy and the anodic film thickness used. The whole range of shades can be produced on films as thin as 5 /im, so the finishes are also being used in trim applications. Many patents and publications in the electrolytic colouring field now exist and they have been reviewed by many authors . 

Fibres based on AN copolymers containing 4—10% of monomeric units of JO42 and obtained by wet spinning from solutions in DMF have a much better (2-8 times) resistance to multiple deformations than PAN fibres and have a higher light-fastness than PAN fibres. They are, however, inferior to the latter with respect to abrasive resistance and thermal stability. 

Amination A/-Methylolacrylamide in presence of Lewis acid catalyst. Further modifications possible by addition to double bond (Scheme 10.61) Amines with durable press resins Improved dyeability with dichlorotriazine dyes at pH 5 without salt, giving 99% fixation Some improvements in dyeability, especially with direct dyes, but light fastness can be a problem... 

Enhanced dyeability with anionic and reactive dyes, the latter applied under neutral or slightly acidic conditions. Reduced light fastness and marked dulling with some dyes... 

Dyeable neutral without salt good results with some high-reactivity dyes (dichlorotriazine and difluoropyrimidine) but not with some other types (monochlorotriazine and dichloroquinoxaline). Washing fastness very good but light fastness lower... 

Ethylenediamine derivative of Hercosett Scheme 10.64 About 95% fixation of low- or high-reactivity dyes under slightly acidic conditions without salt, but light fastness still inferior... 

Polyepichlorohydrin and dimethylamine Polymerisation of epichlorohydrin in carbon tetrachloride with boron trifluoride/ether catalyst, then reaction with dimethylamine. Applied to cotton by exhaust method or pad-dry. Scheme 10.65 Good yields with direct dyes using only 2 g/l salt. Excellent build-up with most reactive dyes only 10% of normal salt usage needed for low-reactivity dyes and none for highly reactive types. Washing fastness very good but light fastness impaired. 

A third approach utilised copper salts, especially copper(II) sulphate, in conjunction with dyes containing chelatable groupings such as salicylic acid or o,o -dihydroxyazo moieties. Indeed, special ranges of copperable direct dyes, for which the treatment with copper(II) sulphate was really part of the dyeing process rather than an optional aftertreatment, were introduced. In the past the main use of this chelation treatment was to enhance light fastness, but it is little used for this purpose nowadays. 

Antimicrobial agents may adversely affect the light fastness of nylon dyeings or cause yellowing of the fibre. The six antimicrobial treatments listed in Table 10.51 have been... 

The premium FBAs 11.15 and 11.17 already mentioned are of importance on nylon because of their superior fastness properties. As on cotton, the distyryldiphenyl structure 11.15 has slightly higher light fastness than the D AST-type brighteners. In contrast to its performance on cotton, however, it has excellent fastness to washing on nylon. 

The light fastness of the vic-triazole 11.17 on nylon is 4-5 as on cotton this is significantly superior to that of the DAST derivatives. Unlike the DAST types, the vic-triazole is also stable towards a sodium chlorite bleach. Applied to nylon in combination with sodium chlorite, compound 11.17 can give exceptionally high whiteness and excellent fastness properties. 

Light fastness is improved by the introduction of electron-withdrawing substituents into ring A, but is adversely affected by electron-donating substituents. 

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