Contact adhesives provide the advantage of high initial strength. They are based on polymers that exhibit the ability to bond to themselves as dry adhesive films (auto-adhesion). Both surfaces to be bonded must be coated and the adhesive dried. Coated surfaces bond immediately on contact so care needs to be taken in positioning the substrates prior to contact since re-positioning is nearly impossible. Once the bond has been made, it is typically pressed or rolled to insure complete contact. The high initial strength of contact adhesives makes them ideal for a variety of laminating applications. Because the adhesive is dried before bonding, contact adhesives can be used to bond large areas of non-porous substrates.
Contact adhesives are available in both solvent based and water based dispersion systems. Solvent based systems dry faster and allow bonds to be made more quickly. Because they contain flammable solvent, proper care must be taken for safe handling. Solvent based contact adhesives are also regulated due to environmental concerns. The drying time for water based contact adhesives can be shortened by heating or increased air movement. Both solvent and water based contact adhesives are well suited for automated assembly of wide area laminates. Adhesive can be applied by spray or roller and drying is accelerated by use of a drying oven. Contact adhesives are used extensively to assemble counter tops, building panels, furniture, and side panels for recreational vehicles.
Water based contact adhesives must be dried completely to obtain optimum adhesion and water resistance particularly on metal substrates. In some instances, metal substrates must be primed or coated. Water based systems require more care in application since dry adhesive is no longer dispersible in water, requiring solvent and sometimes abrading to clean up application equipment. In addition, water based contact adhesives may require use of stainless steel application equipment and plastic piping. Solvent based contact adhesives are typically more tolerant of surface contamination.