| 摘要 |
<p>Bleaching wood pulp is mfd. from wood shavings in a single stage in a thermomechanic pulper by adding a bleaching agent (I) to the wood to bleach it as it is being pulped. Specifically the shavings, preheated to 100-110 degrees C., are pulped in a double disc refiner. A soln. or aq. suspension of (I) is charged to the refiner such that it comes into contact with the shavings at the centre of the refiner. (I) is added at 0.5-5 wt.% based on the wt. of the dried wood solids charged. (I) is esp. H2O2 added as an aq. soln. (0.5-10% by wt.) pH 9-12. (I) can also be an alkali metal dithionite, or (hypo)chlorite. The prod. has improved absorbency and is used in the paper industry for absorbent hygienic products, e.g. disposable paper towels. The single stage process gives products at least as good and in a much faster time than conventional methods.</p> |
