Study on Methods for Removing Extractable aldehyde from Leathers and Furs.

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The present study was carried out to establish the method for removingaldehydes from leather and for. Results obtained were summarized as follows.(1) The collagen fider and rabbit hair were treated with albehydes at different ph and concentrations, and the amount of aldehyde extracted from those samples were determined under various conditions of time and temperature. The results indicated that the aldehydes extracted from these samples increased with an increase of extraction time, and also increased drasticaly with increasing extraction temperature. Formaldehyde, glutaraldehyde have the best tanning potency among aldehydes, because these combine with -amino group of lysine below ph 7.0 to form the cross-linkage between collagen molecules.(2) At present, the determination of formaldehyde, prescribed in "welfare ministry ordinance No.34", is examined for applicability in the case of leathers,however, the results of this investigation suggested that the specification of extraction time … More to one hour might be problematical.(3) In case of the use of artificial perspiration instead of distilled water as extractor, the amount of formaldehyde extracted from formaldehyde tanned collagen fiber decreased with an increase in extraction time by alkaline perspiration. Perhaps, the extractable formaldehyde might be combined to the collagen fiber more tightly in alkaline perspiration.(4) When the formaldehyde treated collagen fibers were treated with solution of sodium bisulfife for removing agent, the amount of extractable formaldehyde decreased. In the case of retanning agents, cationic and anionic resin retanning agents were found to contain a relatively large amount of extractable formaldehyde. One of the chrome collagen fibers, which were retanned with formaldehyde contaning agents, had more than the critical formaldehyde value, 75mug/g. When these retanned collagen fibers were treated with sodium bisulfite solution, the amount of extractable formaldehyde decreased by this removing treatment. Less