Fastness to light

Dyestuffs. The use of thiophene-based dyestuffs has been largely the result of the access of 2-amino-3-substituted thiophenes via new cycHzation chemistry techniques (61). Intermediates of type (8) are available from development of this work. Such intermediates act as the azo-component and, when coupled with pyrazolones, aminopyrazoles, phenols, 2,6-dihydropyridines, etc, have produced numerous monoazo disperse dyes. These dyes impart yeUow—green, red—green, or violet—green colorations to synthetic fibers, with exceUent fastness to light as weU as to wet- and dry-heat treatments (62-64). 

Triphenylmethane dyes comprise one of the oldest classes of synthetic dyes. They are of bdUiant hue, exhibit high tinctorial strength, are relatively inexpensive, and may be appHed to a wide range of substrates. However, they are seriously deficient in fastness properties, especially fastness to light and... 

Most mordant dyes are monoazo stmctures. The most important feature of this class of dyes is excellent fastness to light and washing. Mordant dyes are available ia aU shades of the spectmm with the exceptioa of bright violets, blues, and greens. To be useful, the metal complexes must be stable, ie, must not demetallize when subjected to dyebath conditions and aU aftertreatment processes, especially repeated washings. Chromium forms stable chelate rings with mordant dyes which are not affected by treatment with either weak acid or alkaU (see Coordination compounds). 

An example of an anthraquinone thia2ole that has commercial importance is Cl Vat Blue 30 [6492-78-0] (167) (Cl 67110). This dye exhibits good fastness to light and chlorine. 

The dibtomo derivative exhibits improved fastness to light, washing, and bleach. 

Nylon Blends. Differential dyeiag nylon types and cationic dyeable nylon blends are used primarily ia the carpet iadustry. The selection of cationic dyes for nylon is rather limited most products have very poor fastness to light. These blends are dyed ia a one-bath procedure at 95—100°C. Selected acid dyes are used for differential dyeiag. Disperse dyes will dye all different types ia the same depth. 

Fastness to Light. The ISO test for colorfastness to light is DajlightlSO 105-B01. The textile specimen is exposed to daylight under prescribed conditions, including protection from rain, along with a series of blue wool reference samples that fade at defined, prescribed, different rates. 

Licht-echtheit, /. fastness to light, -effekt, m. luminoiis effect, -eindruck, m. luminous impression. -einstrahlung, /. irradiation (by light), -elnwirkung, /. action or effect of light. 

Nassgussformerei, /. green sand molding, nass-kalt, a. wet (or damp) and cold, -kffhl, a. damp and cold, chilly, -lichtecht, a. fast to light when wet. 

Padfield, T. and S. Landi (1966), The fastness to light of the natural dyes, Stud. Conserv. 11,181-196. 

A white pigment for rubbers and plastics characterised by high tinctorial power, fastness to light, and chemical stability. Titanium dioxide pigments are made in two crystal forms, mtile and anatase, which differ in crystal structure and crystal size. 

The small range of azo condensation pigments has become established only because they combine outstanding fastness to light, heat, solvents and chemicals, finding acceptance for use in paints, printing inks and the coloration of plastics and some synthetic fibres. 

Hydrolysis of ester groups can also occur in certain wool dyes. For example, Cl Acid Red 1 (3.26) loses its acetyl group (Scheme 3.5) on prolonged dyeing in an acid dyebath, the hue becoming bluer and duller and the dyeing much less fast to light. 

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