The Study On Anti-yellowing Of PU Coated Leather-like Fabric

The transfer coating is commonly used in the production of PU leather fabric, polyurethane coating on film release liner is transferred to the fabric by hot stamping manner. made of multi-pattern, multi-style fabric skin feel, excellent performance and price inexpensive, very popular. However, especially in the light of the role of UV, polyurethane leather fabrics prone to yellowing even photo aging, thus solving their problems yellowing polyurethane leather fabric essential for the development. Firstly, the mechanism of yellowing polyurethane film and film properties were studied; screened on the basis of suitable light stabilizers, which can be complex and applied slurry coating to optimize the complex ratio and the amount; improving the transfer coating process, improve the polyurethane leather fabric anti-yellowing properties, the development of anti-yellowing polyurethane leather fabric production technology.By infrared spectroscopy study yellowing polyurethane film before and after the UV spectrum shows: aromatic polyurethane coating film prone to yellowing under ultraviolet light used, mainly due to ultraviolet light leads to decomposition of the polyurethane structure urethane bond was oxidized to the quinone color group, and the benzene ring is attached to the oxidation of the methylene carbonyl chromophore due; yellowing polyurethane film after the reaction has been enhanced UV absorption ability, UV transmittance significantly decreased; by yellowing polyurethane film before and after the heat of heavy(TG), the contact angle analysis and scanning electron microscopy shows that the yellowing polyurethane film after heat resistance decreased, while the aromatic polyurethane due to the carbonyl generated leaving a polyurethane hydrophilic membrane performance improved; surface and cross-sectional structure of the polyurethane film before and after contrast yellowing found that the surface morphology of the polyurethane film was not much change before and after the yellowing, studied light stabilizer and solvent butanone have good compatibility, so and there is not much effect on the polyurethane surface structure after the addition.By studied light stabilizer and solvent butanone compatibility, stability and slurry coating polyurethane film anti-yellowing properties, and found an ultraviolet absorber UV-531, UV-P and a hindered amine light stabilizer LS-622, LS-770 in the coating slurry dispersion, stability and anti-yellowing effect is relatively good, which is a 1: 1 ratio can be complex to use, and further improve the effectiveness of anti-yellowing polyurethane film.The light stabilizer for different color polyurethane leather fabric shows that when single-use UV absorbers and hindered amine light stabilizers, are to some extent improved polyurethane leather fabric anti-yellowing properties. Among them, the anti-yellowing effect of ultraviolet absorbent UV-531 is better, containing UV-531 white leather fabric UV accelerated weathering tester at(50 ℃, 0.41 W / m2) after 24 h yellowing discoloration level reaches 3(obvious discoloration), brown leather fabric discoloration levels to drop to 2(slight discoloration); and hindered amine light stabilizers are generally not anti-yellowing UV absorber good effect. UV absorbers and an anti-yellowing effect hindered amine light stabilizer compound is better than that using a single light stabilizer. White leather fabrics UV-531 and LS-622 complex ratio of 3: 1, in the amount of 2.0% of the best anti-yellowing, UV discoloration after accelerated aging 24 h grade dropped to 2, brown leather fabric after the above-mentioned amount of coating fabrics made of color rating also dropped to two, they belong slight discoloration, indicating that anti-yellowing performance has been improved.Coating process transfer time and stamping temperature polyurethane coating quality imitation leather fabrics and influential anti-yellowing properties, optimized, the optimal white leather fabric coating process for stamping temperature 110℃, transfer time 30s; brown leather fabric coating process is stamping optimum temperature 100℃, time stamping 30s; whether it is white or brown leather fabric leather fabric, after washing their anti-yellowing performance declined slightly, heat-setting process is almost no effect on the anti-yellowing properties.Through the research on the mechanism and yellowing polyurethane film coating process, anti-yellowing polyurethane leather fabric production provides a theoretical basis and technological reference, expanding the prospect of polyurethane leather fabric.