Bleaching nylon

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. 

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. 

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. 

The mechanism of degradation is the loss of polymer cross-linking. This results in the membrane polymer dissolving, similar to a nylon stocking when exposed to chlorine bleach. Damage is irreversible and will continue as long as the membrane is exposed to the oxidizer. 

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). 

Chemistry, Physics, and Biology Laboratories. As a rule, before any artifact is subjected to treatment, the chemistry laboratory determines the causes of any alterations or deterioration. The nature and structure of the artifact, its pigments and inks, are identified to avoid negative reactions to prescribed treatment. Fixatives are recommended if required these may be cellulose acetate dissolved in acetone, soluble nylon, or acrylic resin sprays. Once stains are identified, several possible solvents are selected. For deacidification, either magnesium bicarbonate or barium hydroxide usually is recommended, depending on whether an aqueous or nonaqueous solution is called for. Bleaching is discouraged, but when necessary, hypochlorites are used with suitable antichlors. 

CARBOWHITE CEF is an optical brightener which produces excellent v/hite effects with a neutral/blue cast on cellulosic fibers, nylon, and blends of these fibers, CARBOWHITE CEF is highly substantive and is specially recommended for exhaust application. It can be used in conjunction with a peroxide bleach bath. For pad application, Hoechst recommends their CARBOWHITE CEC. 

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. 

OBA for cellulosics and nylon. Recommended for exhaust application. May be used in Peroxide bleach bath. Neutral/blue cast. 

A very important aspect of dressings production is packaging. The packaging material must allow correct sterilization conditions (e.g. permeation of moisture or ethylene oxide), retain the dressing in a sterile condition and allow for its removal without contamination prior to use. All dressings intended for aseptic handling and application must be double wrapped. For steam sterilization they may be individually wrapped in fabric, paper or nylon and sterilized in metal drums, cardboard boxes or bleached Kraft paper. The choice of method also determines... 

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... 

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