Direct Dyes Resins

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... 

Direct Dyes. These water-soluble anionic dyes, when dyed from aqueous solution in the presence of electrolytes, are substantive to, i.e., have high affinity for, cellu-losic fibers. Their principal use is the dyeing of cotton and regenerated cellulose, paper, leather, and, to a lesser extent, nylon. Most of the dyes in this class are polyazo compounds, along with some stilbenes, phthalocyanines, and oxazines. Aftertreatments, frequently applied to the dyed material to improve washfastness properties, include chelation with salts of metals (usually copper or chromium), and treatment with formaldehyde or a cationic dye-complexing resin. 

Spectrometric methods such as IR spectroscopy give information on the main components of the examined samples (dyes, resins and oily liquids). The main pigments are easily detectable in the IR spectra of inks. Because of its non-destructive nature, Raman spectroscopy is applied in forensic investigations for the identification of inks directly on a document, and for determination of the... 

Economical direct dye fixative. Does not influence shade or lightfastness compatible with resins and most finishes. Applied by exhaust or pad-on. 

There are many direct dyes of which the wet-fastness is improved by after-treatment with a copper salt such as copper sulphate or, alternatively, spedally prepared mixtures of copper salts and cationic resin-fixing scents. Some of the dyes which have been specifically developed for this treatment are the Cuprofix, the Cuprophenyl, and the Coprantine colours, as well as many others not necessarily classified in distinctive groups. Examples of mixtures of copper salts and cationic products for after-treatment are Resofix C and Ct rantex B. 

Inset [Hart Prods. Corp.] Resin condensate fixative fat direct dyes. 

Hipofix. [High Point] Methyl methylol resin fixing agent for direct dyes on cellulosics. 

Anion Exchange Resins as Effective Sorbents for Removal of Acid, Reactive, and Direct Dyes from Textile Wastewaters... 

Taking into account high capacity and selectivity of ion exchange resins for different dyes, they seem to be proper materials for dyes sorption from textile effluents. Applicability of the anion exchange resins in the removal of acid, reactive, direct dyes widely used in the textile industry, from aqueous solutions and wastewaters, was confirmed in some papers [2,15, 20, 23, 25-28]. 

Direct dyes bind to cellulose at nonspecific dye sites on the surface of naturally occurring crystalline areas within the fiber. The binding mechanism is hydrogen bonding or van der Waals forces. This provides for fairly weak binding (typically 2 kcal/mol). As a result, these dyes wash off during end use unless fixatives are applied. These fixatives may be of several types, typically resinous dicyandiamide crosslinking materials. 

As a 1.7 dtex (1.5 den) fiber, it can be spun into yams with a better strength conversion factor than other ceUulosics, aUowing rotor-spun Tencel to outperform ring-spun cotton or modal viscose. Fabrics can be made at high efficiency, and prove to have the anticipated tear and tensUe advantages over other ceUulosics. Direct, reactive, or vat dyes can be used, and easy care properties can be achieved with less resin finish than normal. Tencel could therefore be positioned as a new premium quaUty apparel ceUulosic and not simply as a long-term replacement for viscose. 

Carpet. Carpet, an important textile, may also be treated to provide water and oU repeUency however, the principal functions of the current carpet treatments are to provide soU and stain resistance. High quaUty carpets, especiaUy those made from nylon, polyester, or wool, have a significant proportion of the surface coated with fluorochemical materials. The treatments can be spray-appUed to a finished carpet or appUed directly to the fiber during the spinning or dyeing operations. Suitable fluorinated resin materials are readily avaUable from 3M or DuPont. 

Table 5.5 Prominent peaks in the mass spectrum of aloe resin (see Figure 5.13), interpretation following the literature. The dyes are not detected as sodium adducts but as radical cations formed by direct absorption and ionisation of the laser energy...

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