Defoaming agent for papermaking
The progress of the papermaking industry is the use of papermaking defoamers, which makes the produced paper whiter and smoother. The foam in the papermaking white water mainly comes from many chemical additives added to the pulp pool during the pulping process, such as filter aids, retention aids, wet strength agents, sizing agents, etc., which are easy to generate bubbles during the pulping and white water closed circulation process.
Since the pulp contains very fine fibers and pigment fillers, these solid substances provide carriers for the adsorption of bubbles. Depending on the fiber, some are adsorbed on the surface of the fiber, and some penetrate into the inside of the fiber. At the same time, fine pigments and fillers are easy to agglomerate on the surface of the bubbles, which enhances the strength of the foam. Of course, there are some fine bubbles dispersed in the pulp. When the bubble content in the pulp is high, the bubbles are easy to merge, and the small ones merge into large ones. The large bubbles are easy to float on the liquid surface due to their low density, which is the liquid surface foam we usually see. Compared with the fine bubbles adsorbed on the fibers in the pulp, the foam on the liquid surface is larger.
The generation of foam on the liquid surface may also be caused by factors such as the pulp not being washed clean, the fiber swelling being incomplete, the pulp falling in a waterfall shape, the air leakage of the pulp pump, etc., which mixes a large amount of air into the water to produce foam. The hazards of long-term foam: first, the foam floating on the liquid surface; second, the air dissolved in the pulp; third, the tiny foam adsorbed on the fiber surface and inside the fiber.
Then let’s look at the hazards of foam. The high bubble content in the pulp not only affects the dehydration of the wire, causing paper disease, reducing the machine speed, and causing paper breaks, but also easily reduces the operating efficiency of the pump, increases energy consumption, makes the entire flow system unstable, and even causes the sizing pump to trip and shut down.
According to research, bubbles with a diameter of less than 0.8mm often cause bubbles and poor paper uniformity in the wet paper formed by the wire, hindering the combination of fibers, and the paperboard is easy to delaminate. In severe cases, full-width delamination occurs. General research and production experience show that when the air content in the pulp exceeds 0.5-0.6%, it will have a greater impact on the quality of the paper. Papermaking defoamer is designed mainly for the foaming characteristics of papermaking process in papermaking industry. The use of this product can effectively control pulp and foam overflow and improve papermaking quality. It is widely used in defoaming of papermaking system, and can also be used for defoaming of papermaking wastewater treatment, antifreeze, and distillation system.
