Submitted to: American Leather Chemists Association Meeting
Publication Type: Proceedings
Publication Acceptance Date: April 15, 2007
Publication Date: June 20, 2007
Citation: Liu, C., Latona, N.P., Dimaio, G.L., Cooke, P.H. 2007. Drying Chrome-free Leather using a Combination of Vacuum and Toggling. In: Proceedings of International Union of Leather Technologists and Chemists Societies and American Leather Chemists Association Conference, June 20-24, 2007, Washington, D.C. 2007 CDROM. Technical Abstract: Drying, by which leather acquires its final texture, consistency and flexibility, is one of the most important operations in leather manufacturing. The objective for this research is to obtain an improved drying method, merging toggling and vacuum drying together. This is because vacuum drying offers fast speed and low temperature drying, which is particularly advantageous to heat-vulnerable chrome-free leathers. Adding a toggle action, such as stretching during vacuum drying, can potentially increase the area yield. We explored this composite drying method and investigated how drying variables affect the drying rate and mechanical properties of chrome-free leather that was tanned with glutaraldehyde. Using a statistical experimental design, a second order polynomial equation was derived to quantitatively describe the relationship between the drying rate and three major independent variables: drying temperature, stretch %, and drying time. Drying rate models derived from this investigation provide a clear understanding of the drying process for chrome-free leather. The drying constant indicates that chrome free leather dries faster than chrome-tanned leather. These models will help the leather industry estimate the right drying parameters to dry leather. Our studies showed that stretch % during vacuum drying is the most significant variable affecting the stiffness and area retention of leather. This research indicated that stretching should not be overdone and the preferable length increase should not be greater than 10%; otherwise poor leather properties may result, such as an elongation less than 40% and toughness index less than 1.