Organic Solvent Adhesives

These more traditional adhesives are formulated from solvents containing polychloroprene, polyurethane, acrylic, and natural and synthetic rubbers (elastomers). Solvent based adhesives contain significant levels of volatile organic compounds (VOCs), which are considered to be precursors to smog formation, asthma irritants and are often subject to regulations across the United States and worldwide. These adhesives are applied by brush, roller, and spray or as beads or ribbons either manually or automatically. Solvent based adhesives are available with a variety of drying and bonding times to match the application method and assembly process.  These adhesives are typically intermediate in final bond strength and heat resistance providing good bond line flexibility.  Because they contain organic solvent, they are less sensitive than other types of adhesives to contaminates on the surfaces to be bonded.

Two major classes exist:

1. Wet Bonding Adhesives
These adhesives build strength through the evaporation of the solvent. After application of the adhesive, the substrates must be bonded while the adhesive is still liquid. Final bond strength is obtained after the remaining solvent evaporates from the bond line.

2. Contact Adhesives
For this class of adhesive, both substrates are coated with adhesive and any solvent present is allowed to evaporate before the bond is made. The bond is formed by bringing the two coated substrates together using only enough pressure to insure intimate contact of the two adhesive films, the adhesive having sufficient tack or auto-adhesion to provide early bond strength. Bond strength builds over time as the two adhesive surfaces remain in contact and the films co-mingle. Contact adhesives provide much higher initial strength and generally have higher final strength, heat resistance, and creep resistance than wet bonded solvent based adhesives.