Optical brighteners/bleaches

Optical amplifiers Optical bleaches Optical brighteners... 

Descriptive terms such as fluorescent whitening agents , optical brighteners and optical bleaches have all been used for the products described in this chapter as FBAs. Many of these terms have validity and the term fluorescent brightening agents is preferred here only because it has been adopted in the indexes of Chemical Abstracts. 

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. 

Optical brightener for polyacrylonitrile fibers. HOSTALUX NC is stable in sodium chlorite bleaching liquors and can, therefore, be used in combination with such a bleach. 

Optical brightener for polyacrylonitrile fibers. Because of the high brilliance of the brightening effect, most acrylic fibers do not require a sodium chlorite bleach. 

The goods are entered into a bath containing 2-3 volume H O, 1 g/1 sodium hydroxide flake, 0.2 g/1 peroxide stabiliser, 0.25 g/1 sequestering agent and 0.002 to 0.05 g/1 free radical suppressor at 40 C, the temperature is raised to 85 C and then the treatment continued for 1 h. The treated goods are then cooled and rinsed thoroughly. When appropriate, selected optical brighteners may be incorporated in the peroxide bleach bath. 

Optical brightening agents are applied to textiles at the time of scouring, bleaching or finishing. When chlorite bleaches are used anti-chlorinating measures must... 

The one bath two stage bleaching and brightening of acrylic fibres is quite popular. In this procedure, the material is boiled with chlorite, using oxalic acid as an accelerator for about 30 min, the bath is cooled to 80 C and excess chlorine is eliminated with sodium hydrosulphite. In the second phase, the optical brightening agent is added and the bath is again heated to the boil in 30 min and the material is treated at this temperature for further 30 min. The material is then worked up in the usual manner. 

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