What is the strengthening mechanism of dry strength agent

Date2021-09-25 16:02:38 Hits: CRM

Many water-soluble polymers that can form hydrogen bonds with fibers can be used as dry strength agents. In the early stage, starch and natural vegetable gum were used as the raw materials for this product. Later, the development of oxidized starch, cationic starch, anionic starch, starch and other starch derivatives, carboxymethyl cellulose and other water-soluble cellulose derivatives, methyl cellulose and Hydroxyethyl cellulose can improve the dry strength of paper. In the late 1950s, high-molecular polymers such as polyacrylamide and polyamines and water-soluble resins were used in the papermaking industry and achieved a good increase.

  The formation mechanism of dry strength and the strengthening mechanism of dry strength agent

   Hydrogen bond strength is the main way to produce paper bond strength. The cellulose molecule contains quite a lot of hydroxyl groups. If a superfine fiber is composed of 300-500 glucose units, and each glucose group is composed of three hydroxyl groups, there are 900-1500 hydroxyl groups in total. Therefore, the strength of hydrogen bonds formed by many ultrafine fibers is relatively large. From the point of view of molecular structure, it is a kind of high molecular polymer containing polyhydroxyl groups.

  The main enhancement mechanism is:

   (1) The hydrogen bond forming group in the molecule forms a hydrogen bond with the hydroxyl group on the surface of the fiber. The more hydrogen bond bonding points, the stronger the binding force.

  (2) is a dispersant, which can make the fibers more uniformly distributed in the pulp, thereby increasing the bonding points between the fibers and between the fibers and the polymer, thereby increasing the dry strength.

   Therefore, dry strength agents are required to have some molecular weight and active groups, which can form hydrogen bonds with the hydroxyl groups of the fiber to meet the reinforcement requirements of paper.

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