Starch adhesives are readily available, low in cost, and easy to apply from water dispersion. They are considered to be the least expensive class of paper packaging adhesive. Formulated starch adhesives can be applied hot or cold, but generally are used hot. Starch adhesives cure by the loss of moisture. These adhesives cure to a thermosetting structure, they have excellent heat resistance. Disadvantages include poor moisture resistance and mold growth.
RESULTING PROPERTIES
The first major commercial process for producing starch adhesives was the Stein-Hall Process. This was introduced in the 1930s for the purpose of producing an adhesive for corrugated boxes. The Stein-Hall system combines the properties of an 8-9% cooked starch paste and a 25% starch slurry in a two-component, two-container process as indicated in the above table. Sodium hydroxide is used to lower the gelation temperature and borax to increase the tack.
