Bleaching of nylon

Nylon is also supplied in quite white state. Bleaching of nylon is normally carried out where the nylon has been discoloured by heat-setting treatment. The problem of discolouration is comparatively less in the case of nylon 6 than that of nylon 

6 due to the lower temperature required in the spinning process and lower softening point of nylon 6,6. 

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Post cleanup of polyester yarns and fabrics Bleaching of nylon... 

This product gives odor inhibition and provides an excellent aid to bleaching of Nylon and Cotton. Also serves to chelate ions that become available in bleaching. 

Antioxidant for nylon fabrics. Prevents yellowing during peroxide bleaching of nylon. 

Peracetic acid is particularly suitable for bleaching of nylon because this can be applied in a liquor which pH is virtually neutral and hence there is no danger of loss of strength of nylon fibre. The bath is set with pre-dissolved chemicals containing... 

Reductive bleaching of nylon is normally employed under acidic conditions. 

The chemical and physical properties of nylons have been extensively described (76). Nylon will not support mildew or bacteria. Moth larvae may bite their way through nylon if imprisoned. In soil burial tests, it was found that nylon 6 retained more than 95% of its strength after six months. By contrast, wool and cotton were rotten after one month (3). Nylon may be affected by chlorine bleach, and strong oxidizing bleaches can damage it (31). 

Blends of nylon and cellulosic fibres may be bleached with either H O, or NaClOj, using batchwise or continuous method [145, 146]. 

Traditional uses of the alkyldiphenyl oxide disulfonates include (1) emulsion polymerization to yield faster run times with less reactor waste and smaller particle size (2) acid dyeing of nylon carpet fiber as leveling agents to promote an even distribution of dye, (3) crystal habit modification to alter crystal shape and size and (4) cleaning formnlations to provide solubilization in strongly acidic, caustic, and bleach environments. 

Phloroglucinol is Hsted in the Colourindex as Cl Developer 19. It is particularly valuable in the dyeing of acetate fiber but also has been used as a coupler for azoic colors in viscose, Odon, cotton (qv), rayon, or nylon fibers, or in union fabrics containing these fibers (157). For example, cellulose acetate fabric is treated with an aromatic amine such as (9-dianisidine or a disperse dye such as A-hydroxyphenylazo-2-naphthylamine and the amine diazotizes on the fiber the fabric is then rinsed, freed of excess nitrite, and the azo color is developed in a phloroglucinol bath at pH 5—7. Depending on the diazo precursor used, intense blue to jet-black shades can be obtained with excellent light-, bleach-, and mbfastness. 

Synthetic Fibers. Most synthetic fibers are sufficientiy white and do not requite bleaching. For white fabrics, unbleached synthetic fibers with duorescent whitening agents are usually used. When needed, synthetic fibers and many of theit blends are bleached with sodium chlorite solutions at pH 2.5—4.5 for 30—90 min at concentrations and temperatures that depend on the type of fiber. Solutions of 0.1% peracetic acid are also used at pH 6—7 for 1 h at 80—85°C to bleach 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. 

Other stilbenes of use in detergents are the DAST based (3.49), the triazolo compound (3.56), derived from DAST, and the bis-stilbene (3.57). The latter two are more stable to the newer bleaches but are also more expensive than the simpler DAST based FBAs. They are also used as premium brighteners for cotton and nylon/cotton blends. 

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