Bleaching blended fabrics

Other fibers blended with polyesters in numerous blended fabrics requke alternative methods of preparation. Generally, the scouring and bleaching procedures used for these blends are those employed for the primary component of the blended fiber or for the component that most influences aesthetic appearance. 

Alkaline boil and bleaching of fabrics (cotton and blends)... 

PLEX HT is a blend of chelating agents which has the ability to dissolve iron rust from cotton and cotton blend fabrics in strong caustic solutions such as are used in saturation of cotton fabric prior to continuous peroxide bleaching. It also has the ability to keep the chelated iron from redeposition as the pH drops during subsequent rinsing. 

SEQ 100 is used in preparation of cotton and cotton blend fabrics and also can be used in scouring synthetic fabrics when there is a substantial amount of interfering heavy metals on the fabrics. A concentration of 0.1% on the weight of the bath in the caustic scour prior to peroxide bleaching will remove calcium, magnesium and copper but very little iron as the metal or as the rust. If it is necessary to remove ron or rust, other products such as SEQ CF in strong caustic are recommended. 

Peracetic acid can also be used for bleaching polyester/cotton blended fabrics with a solution containing 4 g/1 peracetic acid, 1 g/1 tetrasodium pyrophosphate (stabiliser) and 1 g/1 wetting agent with a liquor ratio of 5 1. Peracetic acid has a pH of about 1.5 and the bleaching bath solution is adjusted to pH 5.5 with the help of dilute alkali. The material is entered cold and run for 10 min. Then the temperature is raised to 65-70 C in 15 min and bleaching is continued at this temperature till the concentration of peracetic acid drops to 0.09 g/1. The fabric is then washed thoroughly... 

A single stage combined scouring and bleaching of polyester/cotton blended fabric can also be done for economy. There are various approaches which include alkali treatment with detergent and peroxide hot bleach alkali treatment with detergent and sodium chlorite bleach sodium chlorite and peroxide bleach and peroxide cold and peroxide hot bleach. 

For polyamide/wool blended fabrics fluorescent brightening agents (1 -2%) are applied following hydrogen peroxide bleaching in presence of stabiliser (3-5 g/1). The treatment is carried out at 70-75 C for 45-60 min and then rinsed and dried. 

Many continuous processing machineries have been developed over the past few decades by which cotton and polyester/cotton blended fabrics can be desized, scoured and bleached in one single operation. 

Uses Scouring agent, penetrant, emulsifier, degreaser, cleaner for continuous desizing, scouring, and bleaching of cotton and cotton/polyester blended fabrics or yarns, and greige fabrics and yarns... 

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. 

In a recent detailed evaluation of Cl Fluorescent Brightener 393 on polyester, this product was incorporated into the polymer melt. The prebrightened fibre was blended with cotton and fabric knitted from these yarns was scoured and bleached. It was demonstrated... 

The best laundry procedure for 100% cotton and 65/35 polyester/cotton fabric is to presoak the fabric for 3 hours in the washing machine filled with warm water (70 liters at 50°C) to which 280 mL of chlorine bleach has been added. After the 3 hours, empty the machine, and give the fabric a single warm wash (at 50°C). Less than 0.1% chlorpyrifos residue remains on both cotton and polyester/cotton when the bleach soak pre-treatment is used however, when a single wash, without the bleach pre-soak is used, approximately 40% of the chlorpyrifos residue remains on the cotton fabric and 28% on the polyester/cotton blend. 

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. 

BURCO SCOUR VAR-DF3 is particularly effective for J-Box and Kler bleaching, and for prescouring, of 100% cotton and polyester/cotton blends. It combines the solvents and emulsifiers to penetrate and remove troublesome oils and waxes by holding them in suspension, thus preventing any redeposit on the fabric. 

CNC REZ BLEND OS treated fabrics are highly resistant to chlorine bleaching and will not yellow at commonly encountered elevated temperatures. 

STABILIZER DR-9 may be used to stabilize peroxide bleach baths for cellulosic fibers alone or in blends, in soft or hard water, in hot or cold bleach procedures, and on yarns or white or yarn-dyed fabrics. 

Proprietary blend. Extremely effective liquid stabilizer for hydrogen peroxide bleach baths. It is a complete replacement for sodium silicate, eliminating the problems of silicate deposits on equipment and fabric. 

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