Tanning Properties of SWL

Abstract

The tanning properties of SWL (sulfite waste liquor) obtained on preparing dissolving pulps from Japanese red pine (Pinus densiflora) were investigated.The methoxy contents (M) of SWL and vegetable tannins were determined. M of the tannin (by the hide powder method) of chestnut, wattlebark and SWL were 0.8, 0.4 and 11.4%, and M of the nontannin of these were 1.4, 3.1 and 3.0 %.M g/cc vegetable tannin liquor when tannning hides decreased gradually, but M % of solids of this liquor increased clearly. M of adsorbed materials in the leather tanned by the fresh wattlebark and chestnut were 0.4 and 0.8 respectively. Therefore, in this case, it means that thetannin was only adsorbed and the nontannin was not scarcely adsorbed by the hides.However, M of the adsorbed materials in the leather tanned by the fresh SWL were 6.4-9.0 %. Therefore, in this case, it means that the nontannin of SWL was fairly adsorbed by the hides. M of the adsorbed materials in the leather tanned by the mixture of SWL and the vegetable tannin were determined. The vegetable tannin was not adsorbed by the hides prior than SWL in themixture, as the tannin content of SWL to the vegetable tannin was lower than 1/2.