挤压预处理对制浆性能的影响

对螺旋挤压机挤压后的木片生产化学浆和磺化化学机械浆(SCMP)的制浆性能进行了探讨.研究发现,挤压后的木片部分抽出物、半纤维素被溶出,纤维受到一定程度的损伤.挤压显著改善了木片的药液渗透性能,用于生产化学浆(KP和Soda-AQ)时,14%用碱量下得到的纸浆硬度与常规制浆方法20%用碱量相近,而筛渣率、碱耗明显降低,制浆得率相近.由于纤维损伤,纸浆强度性能下降,而打浆性能得到改善.比较而言,挤压更适合Soda-AQ法制浆.挤压对含节子的木片的化学法制浆性能改善效果更为明显.挤压虽显著改善木片的磺化效果,可能机械损伤大于磺化的改善,最终SCMP纸浆强度性能没有得到提高.

Influence of Compressing Pretreatment on Pulping

The chemical and SCMP pulping properties with chips compressed by screw extrusion machine were discussed in the paper. The results showed that parts of extractive and hemicellulose of compressed chips were dissolved; also fibers were damaged in certain degree. The compression improved impregnability of solutions obviously, which led to reduce the dosage of active alkali from 20% to 14% in conventional KP and soda-AQ pulping and produce the pulp with similar kappa number and screened pulp yield, but rejects and alkali consumption were decreased obviously. The pulp strength was deteriorated due to the damaged fibers, but beating performance was improved. Comparatively screw extrusion pretreatment was more suitable for soda-AQ pulping process particularly for the knot wood chips. Sulfonation of chips was improved after compressing, however the strength of SCMP was not increased, it was possibly attributed to the heavy damage of the fibers.