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Introduction to Dry Strength Agent
Source: | Author:kesikeen | Publish time: 222 days ago | 57 Views | Share:
  Most of the natural and synthetic dry strength agents are hydrophilic polymers. These polymers are dispersed between the fibers to increase the number of bonds between the fibers, thereby achieving the purpose of improving the strength of the paper. Most dry strength agents contain cationic groups attached to the main chain ring, which increases the bonding force between the polymer and the fiber and improves the retention of the polymer. Commonly used dry strength agents include natural polymers such as starch and its modifications (such as cationic starch, anionic starch), synthetic polymers such as polyacrylamide, glyoxal polyacrylamide and polyvinyl alcohol, and other water-soluble natural products Class dry strength agent. In most cases, the effective dry strength effect can be achieved by adding only 0.1%~0.35% of such substances. my country is dominated by anionic polyacrylamide and modified starch.

  The strength of paper is affected by many factors, firstly it depends on the bonding force between the fibers in the paper and the strength of the fibers themselves, as well as the arrangement and distribution of the fibers in the paper. The most important thing is the bonding force between fibers. The bonding force of fibers generally has four types: chemical bond, hydrogen bond, van der Waals force and fiber surface interweaving force. Among them, the hydrogen bonding force is the main way to produce the bonding strength of paper. The cellulose molecule has quite a lot of hydroxyl groups. The hydrogen bonding force formed by countless microfibers is very large, which is the main reason for the dry strength. From the characteristics of their molecular structure, dry strength agents are mostly high molecular polymers containing polyhydroxyl groups. This is the basis for the formation of hydrogen bonds between the cellulose molecules. The hydrogen bond forming groups in the dry strength agent molecules and the fiber surface The hydroxyl groups form hydrogen bonds. For example, the free glucose hydroxyl of starch participates in the formation of hydrogen bonds of cellulose molecules on the fiber surface, so starch increases the binding force of internal fibers and increases the number of hydrogen bonds on the natural bonding surface between two bundles of fibers. At the same time, the dry strength agent has a certain effect on the paper forming process. The dry strength agent acts as a high-efficiency dispersant at this time, that is, the dry strength agent makes the fiber distribution in the pulp more uniform, and provides more fibers and fibers and high Intermolecular bonding, thereby increasing the dry strength.