| 摘要 |
<p>Leather is chrome tanned by (a) pre-tanning the acidified hides with Cr-(III) salts and (b) completing the tanning with mixts. of Cr-(III) salts, acid binding agents and >=1.6 mole, pref. 2-3 mole, 4-6C aliphatic dicarboxylic acids and/or aromatic di- and/or tricarboxylic acids with 8-13C and/or salts per mole Cr2O3 in the Cr-(III) salts used for the final tanning. The components are added, pref. together, in powder form, ensuring that the total amt. of Cr2O3 present is 1.2-2%, esp. 1-5-1.8% on the wt. of the hides, and that the tanning is carried out with a bath wt. of =100% (w.r.t. the wt. of the hides) to a final pH value of >3.6, esp. 3.8-4.2. Process improves the usage of the Cr cpd., thus making the tanning more economical and facilitating treatment of effluent water from the process.</p> |
