Light optical brighteners

Some laundry detergents contain optical brighteners. These are fluorescent dyes that glow blue-white in ultraviolet light. The blue-white color makes yellowed fabrics appear white. 

Fluorescence in UV radiation is a frequently used method for detection of TLC spots, e.g. of Tinuvin 326 [42]. The fluorescence emitted by optical brighteners under UV light on a thin-layer plate has been utilised as a means of analysing these compounds [42]. On the whole, the use of fluorescence detection in poly-mer/additive analysis of extracts is certainly not overwhelming. Applied fluorescence has been described in a monograph [156]. 

The photophysical phenomena of fluorescence and phosphorescence have found varied applications in fluorescent tube lights, X-ray and TV screens, as luminescent dials for watches, as optical brighteners in white dress materials, as paints in advertisement hoardings which show enhanced brilliance by utilizing fluorescence, for detection of cracks in metal work, for tracing the course of river through caves, as microanalytical reagents, and so on. 

Sodium Tripolyphosphate, Light Density Sodium Metasilicate, Pentahydrate Petro 22 Powder Optical Brightener... 

The interesting photophysics and photochemistry [37, 38] of stilbenoid compounds make them suitable for applications in materials science. In addition to well-established applications, such as in optical brighteners, others arise in light-emitting diodes (LED), in non-linear optics (NLO), and in optical imaging, storage, and switching techniques. 

In daylight optical brighteners can thus compensate for the esthetically undesirable yellowish cast found in white industrial substrates, such as textiles, papers, or plastics. Furthermore, since a portion of the daylight spectrum not perceived by the eye is converted to visible light, the brightness of the material is enhanced to give a dazzling white. 

Figure 7.1 illustrates the action of optical brighteners [1-3], White substrates show a yellowish cast because their reflectance for incident visible light is lower at short wavelengths than at long ones (curve a), i.e., they absorb short-wave-length light. 

Figure 7.2 illustrates the processes involved in light absorption and fluorescence by optical brighteners [4-8],... 

The optical brightener Palanil 50—it makes your clothes look whiter than white and your T-shirts fluoresce in UV light—can be disconnected by the Wittig strategy to two molecules of the phosphonium ylid 51 and one of the dialdehyde 52. The availability of the dialdehyde, used in the manufacture of terylene, makes this route preferable to the alternative. 

Acrylics. Manufacturers of acrylic fibers have not generally published or confirmed the chemical composition of their fibers (116). Acrylic fiber will generally contain 85-94% acrylonitrile the balance is made up of comonomers having a specific function, such as to provide dye affinity for specific dye classes or to regulate diffusion of dye into the fiber. A list of typical comonomers has been published (116). Acrylic fibers may also contain heat (117) and light stabilizers (116). They may also contain a delustrant such as titanium dioxide. Some products contain optical brightening agents. These materials probably never exceed 4r-5% of the total composition. The cross-sectional shapes of the fibers vary (116). 

CONDENSOL A Is a catalyst which contains ammonium nitrate as active substance and Is used mainly for the resin finishing of regenerated cellulose. It is liable to change the shade of coloured goods, and it may also impair the light fastness of optical brighteners. 

Triazoles and their benzo derivatives have attracted considerable attention because of their theoretical interest, and synthetic value, as well as for their numerous applications in industry and agriculture due to their extensive biological activities and their successful application as fluorescent whiteners, light stabilizers and optical brightening agents. 

---