Light stabilizers general

The process of post-chlorinating PVC was carried out during World War II in order to obtain polymers soluble in low-cost solvents and which could therefore be used for fibres and lacquers. The derivate was generally prepared by passing chlorine through a solution of PVC in tetrachloroethane at between 50°C and 100°C. Solvents for the product included methylene dichloride, butyl acetate and acetone. These materials were of limited value because of their poor colour, poor light stability, shock brittleness and comparatively low softening point. 

Light Stability of Chlorinated Dibenzo-l -dioxins. A known concentration of chlorinated dibenzo-p-dioxin was placed in a quartz 1-cm path length cell. A General Electric R.S. sunlamp was placed either 0.5 or 1.0 meters from the face of the cell. The stability of the chlorinated dibenzo-p-dioxin was monitored using ultraviolet spectroscopy. 

Phenazine leucos are generally more reactive and more susceptible to air oxidation than the thiazines and oxazines. Incorporation of electron-withdrawing groups on the acyl substituent at the 10-position of the leuco dye can provide a substantial improvement in the thermal and light stability of the leuco form and it is found that in general the stronger the electron-withdrawing character of the acyl substituents the more stable the leuco is.18... 

PUs are also widely used as coating materials sold as finished polymers, two-part systems, and prepolymer systems. Water-based PU systems are now available allowing easy home use. Aromatic diisocyanate-derived coatings generally offer poor external light stability while aliphatic-derived systems offer good light stability. 

In addition to such general requirements as low volatility, temperature stability, light stability, little, or no odor, etc., there are a number of more basic requirements. 

The main advantages of dye lasers are spectrum coverage (from less than 400 to 1000 nm) and tunability. In general, the laser dyes used nowadays have changed little from those used a decade ago [3]. Coumarins such as (73) and xanthenes such as Rhodamine 6G (74), are the main types. However, fluorinated coumarin dyes such as (75) have higher light stability than their nonfluorinated counterparts [39],... 

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). 

Styron [Dow]. TM for polystyrene resins, general purpose, medium and high impact, heat and impact-heat resistant, and light-stabilized resins... 

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