FWAs Polyesters

Synthetic Fiber and Plastics Industries. In the synthetic fibers and plastics industries, the substrate itself serves as the solvent, and the whitener is not appHed from solutions as in textiles. Table 6 Hsts the types of FWAs used in the synthetic fibers and plastic industries. In the case of synthetic fibers, such as polyamide and polyester produced by the melt-spinning process, FWAs can be added at the start or during the course of polymerization or polycondensation. However, FWAs can also be powdered onto the polymer chips prior to spinning. The above types of appHcation place severe thermal and chemical demands on FWAs. They must not interfere with the polymerization reaction and must remain stable under spinning conditions. 

Research has also been conducted in the area of polymeric FWAs for enhancing whitening of synthetic fabrics and blends. The approach with some of these polymers was to combine the effects of soil release polymers used for polyester with pendant fluorescent units." ... 

Preparation of 2-(4-phenylstilben-4-yl)-benzoxazoles is done by anil synthesis from 2-(4-methylphenyl)-benzoxazoles and 4-biphenylcarboxaldehyde anil—an example is compound 59. These FWAs were used in the past for brightening polyester fibers, but are no longer widely used. 

Uses Leveling agent, dispersant for dyeing polyester fibers with disperse dyestuffs, fluorescent whitening of polyester fibers with disperse FWAs and dyeing the polyester component of polyester/cellulosic blends by the HT process Features Prevents filtration of dyestuffs does not inc. the AOX content of waste-water pumpable resist, to acids, alkali, salts, hard water Properties YIsh.-brn. Iiq. readily sol. in water dens. 1.0 g/ml (20 C) pH 4,0 (10%)... 

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