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Title: A DRYING STUDY FOR GLUTARALDEHYDE-TANNED LEATHER

Author
item Liu, Cheng Kung
item Latona, Nicholas - Nick
item Lee, Joseph - Joe

Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/17/2004
Publication Date: 1/1/2005
Citation: Liu, C., Latona, N.P., Lee, J. 2005. A drying study for glutaraldehyde-tanned leather. Journal of American Leather Chemists Association. 100(1):8-15.

Interpretive Summary: Although 90% of leather is tanned using chrome salts; the environmental and health concerns over the use and disposal of chrome-tanned leather encourage the use of chrome-free leather. The quality of chrome-free leather, particularly glutaraldehyde-tanned leather, in some respects is inferior to that of chrome-tanned leather (for example, in heat resistance). The drying process is one of the key steps governing leather quality. To make quality leather, it is imperative to understand the effects of the different drying methods on the physical characteristics of leather. Our results showed that the method applied in a drying operation significantly affects the physical properties of leather, such as area retention and softness. Observations indicated that toggle drying produces higher area yield; however, it may result in stiffer leather. Our research again showed that residual water content is a key factor for softness. Vacuum drying without toggling yields better toughness and softness. The ratio of strength and stiffness showed a strong correlation with the resultant area retention, which agrees with our previous finding for chrome-tanned leather. The information derived from this investigation will be used by leather manufacturers to select the right drying methods to meet quality demands.

Technical Abstract: The environmental and health concerns over the use and disposal of chrome-tanned leather have encouraged the use of non-chrome-tanned (chrome-free) leather. The drying operation is a critical leather-making step to attain the required physical properties for leather products. We recently conducted a drying study on non-chrome-tanned leather made with a glutaraldehyde-tanning process. Results showed that the physical properties of leather, such as area retention and compliance, were affected significantly by the drying method. Observations indicated that toggle drying produces higher area yield; however, it may result in stiffer leather. Data also revealed that leather with inferior toughness often resulted in poor grain break. Our research again showed that residual water content is a key factor for softness. Vacuum drying without toggling yields better toughness and softness. A dimensionless quantity "toughness index" showed a strong correlation with the resultant area retention, which agrees with our previous findings for chrome-tanned leather.