| 摘要 |
Paper, or similar fibrous sheet materials, can be sized with starch, or a starch-containing material such as flour, and/or hemicellulose, in an economic way by adding an aqs. solution or colloidal dispersion of starch and/or hemicellulose to a paper pulp, and effecting the precipitation of the starch and/or hemicellulose onto the fibres at a neutral or alkaline pH value in the presence of multivalent metal cations capable of forming with starch and/or hemicellulose a complex insoluble at this pH, preferably Ca++, Ba++, Mg++, Sr++, Zn++ or Al+++ cations, introduced in the form of hydroxides, chlorides, nitrates, sulphates or acetates. By this method, losses of the sizing material in water removed from the pulp are eliminated. The pH of the pulp can be adjusted to a neutral or alkaline value by addition of an alkali metal hydroxide or ammonia. The sizing material may be precipated together with a filler. |
