Exposure to sunlight and some artificial lights can have adverse effects on the useful life of polyolefin products. UV radiation can break down the chemical bonds in a polymer. This process is called photo-degradation which causes cracking, chalking, color changes and loss of such physical properties as impact strength, tensile strength, elongation and other properties.
U.V Stabilizer Masterbatches are used to prevent the formation of free radicals, thus protecting the polymer chain to break. As a result, mechanical properties of the polymers will try to remain same even after exposure of Sun rays (outdoor application).
UV light is normally defined as wavelength of light within the region of 280-400nm, while visible light is within 400-800nm. UV light is then subdivided further into UV-A (the lower wavelengths, region around 310nm) and UV-B (slightly higher wavelengths region at around 350nm). Sunlight intensity and composition varies according to latitude, atmospheric effects like humidity etc. So it is important that the additive (or more normally the combination of additives) is selected to suit the exact application. It is therefore important to identify where in the world a final product will be used and the required life span. Other factors that affect the choice of UV stabilization package include product dimensions, type and colour of pigments present and application information such as food or pesticide contact.
U.V. Stabilizers are two types :
A) UVA :
UV Absorber slow down the degradation process by absorbing low wave length light (ultra violet radiation) and dissipating it as thermal energy .
Full form of HALS is Hindered Amine Light Stabilizer. HALS is very effective and efficient stabilizer for polyolefin. They do not absorb UV radiation, but act to inhibit degradation of the polymer. This is a cyclic process wherein the HALS are regenerated rather than consumed during the stabilization process.
Sri Vasavi Pigments use such grades of U.V additives which are synergistic mixture of UVA and HALS and some other UV additives which are based on high molecular wt. and high performance HALS.
UV Stabilizer Masterbatches offered by Sri Vasavi Pigments (P) Ltd. are