Adhesive manufacturers and adhesive suppliers offer a wide assortment of products for temporary and permanent bonding, encapsulating, laminating and sealing. They replace fasteners, bond two flat surfaces together, help contain liquids, fill holes or seams, level surfaces, waterproof objects and mount products to walls or doors. They are mainly made from silicone, acrylic or polyurethane, and are classified according to their adhesive properties, composition and curing mechanism.
Adhesives are used in the automotive, woodworking, appliance assembly, packaging, labeling and plumbing industries, as well as in book binding, shoe making, aquarium and tank assembly and furniture making. The demand from all of these industries gives adhesive manufacturers plenty to do. The construction industry utilizes acrylic adhesive sealing and bonding to replace fasteners during fabrication of doors, staircases, window frames and cabinets. It also uses this adhesive while installing wood floors and laminating counters.
Most adhesives are either a clear or milky white color, and have many different viscosities, meaning the liquid’s resistance to flow. They are manufactured to have various setting speeds, and some remain tacky for a certain amount of time, allowing parts to be assembled without a strict time constraint. Adhesives that have residual tack, such as pressure sensitive adhesives offer repositioning options. Once hardened, some adhesives can not be softened with heat. These are thermoset adhesives. However, some can be softened due to temperature change or moisture contact.
Adhesives can come as one-part or two-part formulas. Two-part adhesives consist of two separate components that need to be mixed or applied to separate adherents and pressed together to create a chemical reaction leading to their bonding properties. One-part adhesives have latent bonding properties that are activated in various ways depending on the type of adhesive.
Activation methods for adhesives include heat addition, pressure, lack of oxygen and loss of water or a different solvent. This last activation method is what happens with anaerobic adhesives. Adhesives can have differing setting temperatures ranging from above 212º F to below 68º F, depending on how much they need to be either cooled or dried to harden. For example, hot melt adhesives are activated to viscous liquid states at elevated temperatures and set when cooled, so care must be taken when selecting an adhesive for these more demanding applications.
Adhesives also vary as far as bond strengths. They can be measured by tensile strength, wet strength, impact strength, fatigue strength, cleavage strength, peel strength and shear strength. Adhesive manufacturers and adhesive suppliers can offer products in the forms of solids (hot melt sticks, powder, granules, pellets, chips, etc.), liquids, pastes, foams, films or aerosol sprays.