Glue

Glue is primarily made from starch. Starch itself is not soluble in cold water, but it can swell into a uniform paste when heated, forming a paste. The ratio of starch to water is generally 1:14. First, mix the starch with cold water, then heat, stir, and swell it. The paste is white or slightly yellow, liquid, sticky, or gelatinous. If the solid content is low, it dries and solidifies slowly and has good resistance to moisture. If the paste is left for a long time, it will rot, and a small amount of preservative is usually added. Glue is widely used in the packaging of paper-based materials, such as sealing of cardboard boxes, bottom adhesion of bags, seams, composite paper, labels, and the production of corrugated cardboard.

Dextrin

Dextrin is an incomplete hydrolysis product of starch, available as a white or yellow amorphous powder. It has high solubility in cold water and can dissolve in water to form a binder. It can be made into different viscosities as required. Dextrin has better adhesion and stable viscosity than paste. It offers superior performance and ease of use. In addition to replacing paste, it can meet the needs of mechanized production for products like corrugated cardboard in packaging. Furthermore, it can be used as a sizing agent for paper and textiles, as well as an additive in ink preparation.

Silica Gel

Water glass is a water-soluble inorganic adhesive. It is a colorless, gray, or faintly pink viscous liquid that dissolves in water. It is typically alkaline. It has a strong adhesive property but poor water resistance. The ratio of glass to water used in packaging is usually 1:2.9 to 3.5.

Water glass is primarily used for bonding corrugated cardboard, cardboard, and spiral paper tubes; in addition, the adhesive can also serve as an additive, such as dextrin, casein, and others.

Casein

Casein, a type of protein glue, is insoluble in water but dissolves in dilute alkalis and concentrated acids. It is formed by dissolving casein in dilute alkali and adding a small amount of additive. It has a light yellow color, good water resistance, and strong adhesion. In packaging applications, it can be used for waterproof labeling on beverage containers, bonding paper cups and bags, cigarette boxes, as an adhesive for composite aluminum foil, and as an additive for synthetic latex.

(S5) Synthetic Adhesive

Synthetic glue, also known as chemical paste, is primarily made by dissolving carboxymethyl cellulose and polyvinyl alcohol in water. It is transparent in color. Adding talcum powder makes it white. Generally, a small amount of formaldehyde is added as a preservative. It can be used for paper packaging adhesives, such as cardboard boxes, paper bags, and labels. It can replace starch paste, being resistant to dampness, insect infestation, and mold.