Ultraviolet stabilizers polyurethanes

The effect of ultraviolet (UV) light on aliphatic clear polyurethanes or aromatic polyurethanes that have had UV stabilizers added can be evaluated using Weather-Ometer . The tests are performed to ASTM D750 or to ISO 4665/3. 

Spandex-type polyurethane fibers are chemically quite stable under normal washing and chlorine containing swimming pool water conditions. Special stabilizers are required for protection against ultraviolet radiation, suntan lotions, human perspiration, etc. 

Ultraviolet Absorbers, Light Stabilizers, and Antioxidants. Ultraviolet absorbers and light stabilizers can be added to urethane coatings in order to increase their resistance to discoloration and to outdoor weathering. UV absorbers are employed to eliminate the radiation in the region of 334 and 411 um that sensitize the polyurethanes and promote an autoxidation process. Light stabilizers on the other hand do not absorb UV radiations but inhibit or control the degradation by other means. 

Aromatic urethanes have been stabilized by complexation of peroxides in the polymer and the effect of prior y-irradiation has been investigated, on polyurethanes.The ageing of polyurethane coatings has been investigated, and light-stable integral skin foams have been developed for polyurethanes. Creep behaviour of polyurethanes on ultraviolet exposure has also been investigated. ... 

Blending two or more polymers offers yet another method of tailoring resins to a specific application. Because blends are only physical mixtures, the resulting polymer usually has physical and mechanical properties that lie somewhere between the values of its constiment materials. For instance, an automotive bumper made from a blend of PC resin and thermoplastic polyurethane elastomer gains rigidity from the PC resin and retains most of the flexibility and paintability of the polyurethane elastomer. For business machine housings, a blend of PC and ABS (acrylonitrile—butadiene—styrene copolymer) resins offers the enhanced performance of PC flame retar-dance and ultraviolet (UV) stability at a lower cost. 

Hydroxy-3,5-ditertiarybutylphenyl)-7-chlorobenzotriazol n. An off-white, nontoxic, crystalline powder with high thermal stability, used as an ultraviolet absorber for polyolefins, PVC, polyurethanes, polyamides, and polyesters. 

Flexible polyurethane foams have good dry heat stability, withstanding temperatures up to 150°C for long periods without serious loss of strength. Above this temperature the formation of biuret and allophanate cross-links is reversed and there is a reduction in load bearing properties. Urethane links are stable up to about 200°C. Exposure to ultraviolet light causes discoloration but no apparent deterioration in physical properties. 

Polymeric hindered amine light stabilizer is excellent for protection against ultraviolet degradation. Applications include polyolefins (polypropylene, polyethylene), olefin copolymers such as EVA as well as blends of polypropylene with elastomers. Also effective in polyacetals, polyamides, polyurethanes, flexible and rigid PVC, and PVC blends. 

Prevents ultraviolet degradation in polypropylene, polystyrene, ABS, polyurethanes, polyacetals, and polyamides. It provides outstanding long-term stability by a radical trapping mechanism similar to that of hindered phenols. Very effective for articles with a high surface area such as films and tapes. 

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