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Title: Polymeric Coatings Containing Antioxidants to Improve UV- and Heat Resistance of Chrome-Free Leather

Author
item Liu, Cheng Kung
item Latona, Nicholas - Nick
item Dimaio, Gary
item Cooke, Peter

Submitted to: Journal of American Leather Chemists Association
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/12/2007
Publication Date: 6/1/2008
Citation: Liu, C., Latona, N.P., Dimaio, G.L., Cooke, P.H. 2008. Polymeric Coatings Containing Antioxidants to Improve UV and Heat Resistance of Chrome-Free Leather. Journal of American Leather Chemists Association. 103(6):167-175.

Interpretive Summary: There is an increasing demand from the automakers for the production of automotive leather. UV and heat can have a detrimental effect on the durability of leather, especially for instrument panels and consoles, where temperatures are extremely high. We have been working on the development of a finishing process using environmentally-friendly antioxidants that improve the UV and heat resistance of automobile upholstery leather. We added tocopherol (Vitamin E), a natural antioxidant, to the coatings of leather that had been tanned with an organic tannage without using chromium salts. Following exposure to artificial sunlight, the treated samples were evaluated for color stability and mechanical properties for the efficacy of UV- and heat resistance. Observation showed that leather treated with tocopherol resulted in significant improvement in strength retention and color fading resistance against UV radiation and heat. This research will expand the demand for domestic production of high quality, durable leather, thereby contributing to the viability of the domestic tanning industry.

Technical Abstract: For automotive upholstery leather, UV and heat resistance are very important qualities, particularly for non-chrome-tanned (chrome-free) leather. One of our research endeavors has focused on an environmentally friendly finishing process that will improve the UV and heat resistance of automobile upholstery leather. Both tocopherol and butylhydroxytoluene (BHT) are well-known antioxidants commonly used in the cosmetic and food industries. Tocopherol has been reported as a potent free radical scavenger and highly protective agent for collagen fibers against UV and heat damage. Experiments were conducted by adding 1 to 5% alpha-tocopherol and mixed-tocopherol to the grain layer finishes (topcoat) of chrome-free leather. The treated samples were exposed to artificial sunlight at a high temperature for 72 hours and then evaluated for the efficacy of UV and heat resistance and by mechanical property testing for tensile strength and toughness. Tests using 5% alpha-tocopherol or mixed-tocopherol showed a significant improvement in color fading resistance against UV radiation and heat. We also studied the addition of BHT to the fatliquoring drums. Observation, however, showed BHT has little effect on the UV and heat resistance of finished leather.