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Title: Drying leather with vacuum and toggling sequentially

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: 10/15/2010
Publication Date: 3/1/2011
Citation: Liu, C., Latona, N.P., Lee, J. 2011. Drying leather with vacuum and toggling sequentially. Journal of American Leather Chemists Association. 106(3):76-82.

Interpretive Summary: Chrome-free leather, which is tanned with an organic tannage without chrome salts, has gradually gained commercial importance, particularly for children’s footwear and automobile upholstery applications. We developed a drying method using a combination of vacuum drying and toggling to improve the area yield of chrome-free leather. Vacuum drying offers fast speed and low temperature drying, which is particularly advantageous to heat-vulnerable chrome-free leathers. On the other hand, adding a toggle stretch after vacuum drying can significantly increase the area yield. We have established an optimal drying condition to achieve a 12% increase in area yield with good leather quality. Tanneries may use this research result to increase area yield of chrome-free leather and therefore better profits.

Technical Abstract: We investigated a drying method that will enable leather to be dried under vacuum and stretch sequentially to improve area yield. Vacuum drying offers fast speed at a low temperature, which would be advantageous to heat-vulnerable chrome-free leather. Adding a toggle action after vacuum drying could significantly increase area yield. Using a statistical experimental design, we formulated regression models describing how drying variables affect mechanical properties and area yield of chrome-free leather tanned with glutaraldehyde. An effort was also made to estimate the effects of conditioning, staking, and drum milling on the area retention gained by toggle stretch. This study showed that the direction the stretch was applied had a significant effect on the area retention. Results also indicated that conditioning and staking have little effect on area retention, whereas the drum milling caused a significant drop in area retention. Our study also showed under an optimal drying condition, a 12% increase in area yield with good properties can be achieved.