Dye Behavior in HYP and Its Implication to Improve the Optical Properties of a Market HYP

摘要

The residual lignin and the other color substances in high yield pulp(HYP)can cause the yellowish tint of the pulp.The use of dyes can minimize or even eliminate the yellowish hue to improve pulp quality.In this study we determined the effectiveness of using a basic dye to decrease the yellowish hue of HYP.The results showed that the basic dye can effectively increase the whiteness and decrease the yellowish color,while the brightness decreased slightly.Also,the basic dye had a strong affinity with the HYP under the typical conditions of stock refining,and the loss of dyes from the HYP under such conditions is negligible.Based on these results,we proposed to add dyes into the HYP manufacturing process to eliminate the yellowish hue.The effectiveness of the dyes added in the HYP manufacturing process and dyes added at the wet end were compared.Higher dye effectiveness can be obtained when it was added in the HYP manufacturing process.Also the dye-added HYP gave more effective performance of PCC fillers and OBA in terms of CIE whiteness and b*.The underlying mechanism for the above experimental observation was proposed.