1. The paper is composed of fiber, hemicellulose, etc., which contain hydrophilic groups and are water-absorbing substances;
2 between the fibers makes paper porous, which water can wet and permeate the paper.
The role of sizing:
1. By adding sizing agent to the inside of the slurry or coating a layer of glue on the surface of the paper, so that the paper can obtain a certain hydrophobic performance;
2. At the same time, the sizing can also improve the strength of the paper, so as to reduce the difference between the two sides and the phenomenon of hair loss and powder loss, and improve the feel and other internal sizing: some hydrophobic substances are added into the sizing material, such as rosin gum AKD ASA, etc., which are combined with the hydrophilic group - hydroxyl group on the fiber surface to make it stay on the fiber surface and reduce the water absorption of the paper; Surface sizing: Coating the paper with water-resistant substances, such as oxidized starch, polyvinyl alcohol, PVA, carboxymethyl cellulose, CMC, etc., so that the paper has a delayed fluid permeability.
Foaming reason: sizing agent itself is also a surfactant, in the operation process, it's mixed with air to appear foam.
Bubbling harm: too much foam will affect the sizing effect, thus affecting the quality of the paper and affect production efficiency.
Hence during sizing, we need to add defoamer to elliminate the foam.
Excellent defoaming agent should have the following points: excellent defoaming performance;Good compatibility with the system.
Xiamen Rickman Chemical Technology Co., Ltd