Dyes from

Nonwandering in order to prevent the dyes from migrating from a layer to the next one in multilayer coatings. 

Various methods of home-dyeing cotton and wool materials using natural dyes made from hulls of butternut, hickory nut, pecan, eastern black walnut, and Knglish walnut have been described (149). As far back as during the Civil War, butternut hulls have been used to furnish the yellow dye for uniforms of the Confederate troops. More recent attempts have been made to manufacture yellow and brown dyes from filbert shells on a commercial scale. The hulls are treated with copper sulfate and concentrated nitric acid to produce a yellow color, with ferrous sulfate to produce oHve-green, or with ammonia to produce mby-red (150) (see Dyes AND DYE INTERMEDIATES Dyes, natural). 

Condensation dyes from 4-nitrotoluene-2-sulfonic acid are the most important of the stilbene dyes. Direct YeUow 11 (Cl 40000), discovered in 1883 and commonly known as Sun YeUow [1325-37-7] is widely used in the paper industry (2,4). 

By this method, sulfur dyes derived from 4-hydroxydiphenylamine are seen to be essentially identical. Similarly, the sulfur dye from... 

Nitro-l-diazo-2-naphthol-4-sulfonic acid prefers the 2-position in spite of the nitro group, and increasing alkalinity favors ortho coupling with diazophenols. 1-Naphthalenesulfamic acid [24344-19-2] (ArNHSO H) and N-nitro-1-naphthylamine [4323-69-7] (ArNHNO ) couple exclusively in the para position. The substitution of resorcinol [108-46-3] and y -phenylenediamine [108-45-2] is compHcated and has been discussed (29,30). The first azo dyes from aniline, eg. Aniline Yellow [60-09-3] (19) (Cl Solvent Yellow 1 Cl 11000) were manufactured in 1861 and Bismark Brown [10114-58-6] (20) (Cl Basic Brown 1 Cl 21000) appeared in 1863. The reaction is as follows ... 

Fastusol Yellow 66 [91-34-9] (25) (Cl Direct YeUow 4 Cl 24890) is a symmetrical primary disazo dye from a tetrazo component (4,4 diamino-2,2 stilbene-disulfonic acid [81-11-8],... 

Amidine Fast Red F [2429-84-7] (26) (Cl Direct Red 1 Cl 22310) is an iinsymmetrical primary disazo dye from a tetrazo component (benzidine... 

Another bright blue dye from diazotized 2-amiao-6-methoxybenzothiazole [1747-60-0] by azo coupling, eg, with 2(/V-ethy1ani1ino)ethano1 is Basacryl Blue X-3GL [12270-13-2] (133) (Cl Basic Blue 41 Cl 1110S). After couphng, the water-iusoluble dye is methylated at the thiazole nitrogen. 

The second widely used class of yeHow couplers is the pi val oyl a ceta n il i des (7) and related compounds bearing a fully substituted carbon adjacent to the keto group. The dyes from these couplers tend to show significantly improved light stabHity and so these couplers have been widely adopted for use in color papers as weH as many projection materials. In general, the dyes have more narrow bandwidths and less unwanted green absorptions (67). 

Reaction with vatious nucleophilic reagents provides several types of dyes. Those with simple chromophores include the hernicyanine iodide [16384-23-9] (20) in which one of the terminal nitrogens is nonheterocyclic enamine triearbocyanine iodide [16384-24-0] (21) useful as a laser dye and the merocyanine [32634-47-2] (22). More complex polynuclear dyes from reagents with more than one reactive site include the trinuclear BAB (Basic-Acidic-Basic) dye [66037-42-1] (23) containing basic-acidic-basic heterocycles. Indolizinium quaternary salts (24), derived from reaction of diphenylcyclopropenone [886-38-4] and 4-picoline [108-89-4] provide trimethine dyes such as (25), which absorb near 950 nm in the infrared (23). 

In disa2o dyes from aminonaphthols, one group exists as a tme a2o group and one as a hydra2o group (17). 

Rate of Diffusion. Diffusion is the process by which molecules are transported from one part of a system to another as a result of random molecular motion. This eventually leads to an equalization of chemical potential and concentration throughout the system, and in the case of dyeing an equihbrium between dye in the fiber and dye in the dyebath. In dyeing there are three stages to diffusion diffusion of dye through the bulk solution of the dyebath to the fiber surface, diffusion through this surface, and diffusion of dye from the surface into the body of the fiber to allow for more dye to diffuse through the surface layer. These processes have been summarized elsewhere (9). 

Some 50% of all nylon is in the form of carpets almost exlusively colored with acid dyes, and around 50% of the carpet manufacturing industry is located in the United States. The acid dyes from Group 1 are those most widely used because they exhibit the rapid diffusion needed to penetrate the bulky yams used in carpets, especially bulk continuous filament yam used in tufted constmctions, with high exhaustion. Their wetfastness properties are generally adequate for most oudets. 

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