The CMP has been accepted as the alternative of LBKP by many traditional types of non-mechanical pulp paper. However, the CMP will affect whitening efficiency of the fluorescent whitening agent because of its fiber properties. When the mixing ratio of the CMP is more than 50%, it is difficult to enhance the brightness of the paper for using fluorescent whitening agent. Compared with the LBKP, more fluorescent whitening agent will be used for the comparable brightness paper made from mixture pulp. It means higher cost and more complex wet-end chemistry. In order to improve the whitening efficiency of fluorescent whitening agent for CMP, aspen BCTMP and APMP was used to research the whitening efficiency. The results showed that the OBA brightening agent had higher whitening efficiency than the VBL brightening agent. When OBA brightening agent was used, adding on the surface of the paper had higher whitening efficiency than adding in wet-end. The dyeing and discoloring for pulp had different effect for whitening efficiency of OBA. Through the 0.5% OBA added in the surface of paper, the paper made from dyeing pulp (brightness 75.8%) was increased its s to 87%, the paper made from yellowing pulp (brightness 75.1%) was increased its brightness to 79.3%.
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