叩解のベッセルピック防止効果
南洋材ベッセルピックトラブルの防止 (第9報)
1988 年 42 巻 3 号 p. 267-274
詳細
1988 年 42 巻 3 号 p. 267-274
Effect of refining on the reduction of vessel picking of hardwood pulp sheet was investigated.
Vessel elements are broken into small pieces by refining, so that the proportion of large vessel elements decreases and that of small fragments increases. Especially high consistency refining is effective for vessel element destruction and it can reduce large vessel content considerably. Regardless of refining methods, the destruction of vessel elements reaches certain level at CSF 400 ml, and further refining gives only small change in size and number of vessel elements.
Result of printing test showed that vessel pick number tends to decrease with reduction of total projected area of vessel elements contained in a given amount of pulp. Larger vessel elements have higher tendency to be picked than smaller ones.
To evaluate vessel-fiber bonding strength, two-layered handsheets were prepared using JPRIMulti-Head with Buna (beech) pulp as under layer and fractionated Lauan vessel elements on the top layer. With increasing refining of Buna pulp, picking of Lauan vessel elements decreased considerably, whereas refining of vessel elements had small effect on vessel pick reduction.
In conclusion, vessel picking reduction by refining is achieved by the following factors ; (1) the reduction of vessel size, especially decrease of large vessel element content, (2) improvement of vessel element-fiber bonding by the improvement of conformability of fibers against vessel elements.
