Why can boric acid enhance the strength of wet glue

I believe many people have seen this corrugated paper, because of its low cost, light weight, easy processing, strength and other advantages, often used as a variety of products packaging materials. In the production process of corrugated cardboard, in order to avoid poor cardboard bonding (foaming, degumming) and other phenomena, it is often necessary to add boric acid to the glue adhesive to enhance the strength of the wet glue and improve the strength, toughness and adhesion of the cardboard. But do you know why boric acid can strengthen wet glue? Today Xiaobian will share with you.

There are many types of corrugated cardboard adhesives, such as starch series adhesives, polyvinyl alcohol and so on. At present, most manufacturers use starch series adhesives. Mainly because the starch adhesive has strong adhesive force, it is easier to penetrate into the paper to produce adhesive force, and boric acid as a complex agent in the paste process mainly plays the role of cross-linking and viscosing, it can make the starch molecules cross-linked, so that the original linear structure becomes a network structure, the starch straight chain length increases, thereby improving the hardness and strength of the glue. In addition, boric acid can also be used as a buffer to adjust the pH value of the glue, so that its performance is more stable, so that the appearance of the cardboard carton is firm and flat, not easy to run, not easy to absorb moisture.

Boric acid is not only one of the components in the manufacture of corrugated paper binders, but also the adhesive solvent in the manufacture of coolin and dextrin binders. Although boric acid is much more pure and useful. However, it should be noted that the amount of boric acid added should be appropriate, too much boric acid will speed up the drying speed, causing the glue to become too brittle and hard, and the phenomenon of cardboard cracking and exploding lines will affect its use effect.