Abstract

Five flame retardants obtained as commercial products or prepared by the laboratory, including amino sulfonic ammonium [sulphamic acid], borax, ammonium polyphosphate, pentaerythritol-dihydrogenphosphate bisestermelamine and phosphated amino resin, were selected to treat wet blue pig. A unified treatment process was used with type and dosage of flame retardant as the two running parameters. The flammability of the leather was tested by two methods – vertical flame test (ALCA Method E 50) and oxygen index test method (ASTM D 2863-74). Besides the fire-safety characteristics, other physical and mechanical properties of leather samples, such as tensile strength, tear strength, breaking stretch [elongation], thickness, Ts, etc. were also evaluated. The results indicate that all of the above flame retardants can enhance the flame resistance of leather. According to the oxygen index (OI) value of the leather samples treated with different flame retardants (12%), the performance of flame retardants on leather can be ranked as: ammonium polyphosphate > borax > phosphated amino resin > pentaerythritol-dihydrogenphosphate bisester-melamine > amino sulfonic ammonium [sulphamic acid]. The results of vertical flammability test indicate that all the tested flame-retardant chemicals can improve the fire resistance of leather and that, ammonium polyphosphate is the best flame retardant at the dosage of 12%. The results of the mechanical properties tests show that all these chemicals, except pentaerythritoldihydrogenphosphate bisester-melamine, have an influence on the leather’s thickness, handle and grain condition and reduce the strength of the leather to a greater or lesser extent.