Humate-dyed, tobacco paper - is treated with magnesium sulphate to insolubilise humate and reduce carbon mon:oxide generation on pyrolysis

摘要

When dyeing tobacco paper with a humic acid salt soln., pref. of pH 7-8, the humate is fixed by treating the paper with sufficient MgSO4 soln. to insolubilise the humate on paper and render it colour-fast. Fixing with MGSO4 soln. achieves desired brown colour intensity and reduces generation of gas phase components, e.g. CO, on smoking. CO generation is lower than that obtd. on fixing with CaCl2 or Mg(OAc)2. Pref. the MgSO4 soln. has a concn. of 1-5.5 wt.%; the humate is esp. Na humate; and acid-soluble material is pref. removed before dyeing, by treating the humate soln. at pH 5-7.