Fabrics bleaching

PENTEX FR is a nonlonic/anlonic blended surfactant that is a biodegradable product for textile wet processing operations. Typical uses are in preparation of fabrics (bleaching), boil-off, and scouring of yarns and fabrics, soaping of fast dye yarns and fabrics particularly when dyed with fiber reactive dyes. 

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

Grey fabric Bleached sample Bleached + NHj Bleached + NHj + resin... 

A comparative study of the bleaching performance of complexes 1-3 with hydrogen peroxide as a function of pH revealed that compounds 1 and 3 show higher activities at PH < 9.5 and compound 2 demonstrates much better results at pH > 9.5. This difference in behavior appears to be related to the generally higher stability of the mixed-valence Mn species under catalytic conditions [6] and it may suggest that catalytic fabric bleaching involves mononuclear species at pH < 9.5 and binuclear species above this pH. 

At millimolar levels of molecular chlorine, the reaction goes to 99% completion in a matter of a few seconds. Above pH 4.4, essentially no molecular chlorine remains in aqueous solution. Hypochlorous acid is a weak acid (pKa approximately 7.5) and thus, near neutrality, both the protonated form and the anion occur at appreciable levels. HCl-free solutions may be prepared by adding salts such as sodium hypochlorite (NaOCl, commercially available as a stabilized 5.25% [0.7 M] solution as a fabric bleach). Either chlorine gas or hypochlorite solutions can be used in large-scale water chlorination applications. In addition to water treatment, chlorine is also used as a disinfectant for beef, pork, and poultry carcasses and also as a bleaching agent for paper pulp and cake flour (Wei et al., 1985). The disinfecting ability of aqueous chlorine is closely associated with its vigorous oxidant character the redox potential for the reactions... 

The reducing action of sulphurous acid and sulphites in solution leads to their use as mild bleaching agents (for example magenta and some natural dyes, such as indigo, and the yellow dye in wool and straw are bleached). They are also used as a preservative for fruit and other foodstuffs for this reason. Other uses are to remove chlorine from fabrics after bleaching and in photography. 

Nondurable Finishes. Flame-retardant finishes that are not durable to launderiag and bleaching are, ia general, relatively iaexpensive and efficient (23). In some cases, a mixture of two or more salts is more effective than either of the components alone. For example, an add-on of 60% borax (sodium tetraborate) is required to prevent fabric from burning, and boric acid is iaeffective as a flame retardant even at levels equal to the weight of the fabric. However, a mixture of seven parts borax and three parts boric acid imparts flame resistance to a fabric with as Utde as 6.5% add-on. 

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. 

Textiles. Sorbitol sequesters iron and copper ions in strongly alkaline textile bleaching or scouring solutions (see Textiles). In compositions for conferring permanent wash-and-wear properties on cotton fabrics, sorbitol is a scavenger for unreacted formaldehyde (252) and a plasticizer in sod-resistant and sod-release finishes (253). 

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