Defoamers are widely used in pulp and paper making
Pulping and papermaking defoamers are very necessary in papermaking, because a lot of foam will be generated in the process of papermaking and pulping. The surface tension of the generated saponified product is less than the surface tension of the black liquor generated by the cooking material, so that it exists in the surface layer of the black liquor and forms a thin film, and foam is formed under the mixing action of air.
The papermaking process is mainly divided into two steps, one is pulp washing and the other is papermaking. No matter which step, foam is inevitable, so defoamers need to be used for treatment. There are many classifications of defoamers. Here I will introduce the characteristics of papermaking defoamers.
Excessive foaming will lead to the loss of fiber and raw materials. Furthermore, the presence of residual air in the wet paper web can affect the filtration rate of paper in the papermaking tooth. At this time, pulp defoamers are the best products to solve foam.
During the pulping process, since the pulp contains natural substances such as fatty acids and resin acids, fatty acid soaps and foaming substances such as fatty acid soaps will be generated after cooking liquid and chemical pulp washing. A large amount of foam will bring certain troubles to the subsequent cleaning, transportation and bleaching, thereby causing the quality of pulp to decline, so defoamers need to be used for treatment. The defoamers used in the pulping process are mainly hydrocarbon defoamers and silicone emulsion defoamers. This type of defoamer can quickly eliminate the foam generated by lignin and some surfactants, and the effect is particularly obvious when pulping and washing.
For the papermaking process, if the foam generated in the papermaking process is not solved, it will cause paper breaks, white water level fluctuations, pump frequency fluctuations, etc., which directly affect the stability and quality of paper production. The papermaking defoamer can effectively inhibit the foaming of white water, and at the same time, it can eliminate the fine bubbles entrained between fibers and the foam on the surface of the pulp. The defoamer can also dissolve the air in the pulp and eliminate the large bubbles on the water surface, so as to avoid the formation of holes, reduce paper breaks and overflow of the pulp storage tank, thereby ensuring the loss of pulp fibers and chemicals, and improving the uniformity and quality of the paper.
Defoamers for papermaking are used in papermaking white water; surface foam containing rosin glue, bubbles adsorbed on fibers in water, surface foam of water-containing modified starch white water system, water foam containing polyacrylamide retention aid system, and surface foam of AKD emulsion white water system are eliminated. Its main characteristics are:
1. Good dispersibility, dynamic defoaming, and silicon-free;
2. Good product stability.
3. Fast defoaming speed and long anti-foaming time;
