Assessment of the Fatliquor’s Degree of Sulfitation Impact on Leather Quality

The fatliquors used in leather provide characteristics such as tensile strength, tear resistance, impermeability, softness, flexibility, and elasticity. Although sulfited fatliquors are widely used in the industry and their properties are well known, the relationship between the degree of sulfitation of the fatliquor and the characteristics of the leather produced still needs to be studied. Thus, this work investigated how various degrees of sulfitation impact the quality of the leather. The methodology consisted of carrying out the sulfitation process of soybean oil by adding oxygen followed by the addition of sodium metabisulfite. The fatliquors obtained were tested for iodine number, ash content, water content, active matter, and combined SO3. The fatliquors were applied to the leather on a pilot scale. The obtained leather was evaluated for softness, grain distension, tear resistance, tensile strength, percentage of extension, and color change in accelerated aging. Results showed that oxidation with airflow produced sulfited fatliquors with a combined SO3 percentage of 2.13%, 3.05%, and 4.27%. The sulfited fatliquor with 4.27% SO3 provided the best results of softness, grain distension, and less color change in accelerated aging. Physical-mechanical tests accomplished results required by the standards.