Adhesives Types and Terms

Types of Adhesives

  • Acrylic adhesives and acrylate adhesives offer fast bonding at room temperature and are highly resistant to environmental conditions. They are able to stick to oily surfaces and many types of materials, including most metals, plastics, glass, ceramics and wood.
  • Aerosol adhesives are industrial spray adhesives that offer convenience and performance for general purpose, foam and fabric, upholstery, screen printing, labeling, palletizing, trim and laminating, high bond high strength, high strength fast tack, pressure sensitive repositionable and temporary or permanent bond applications.
  • Anaerobic adhesives cure in the absence of oxygen. Curing is catalyzed when bonding with surfaces where metallic ions are present.
  • Cold-setting adhesives
  • Conductive adhesives, or electrically conductive adhesives, offer electrical and/or thermal conductivity between components.
  • Cyanoacrylate adhesives are fast setting adhesives commonly referred to as "crazy glue." Only a small amount of these one-component adhesives is necessary to form a rigid plastic layer that has high strength.
  • Epoxies, or epoxy resins, are raw materials that can be formulated to make paints, coatings or adhesives.
  • Epoxy adhesives are very strong and highly heat and chemical resistant. They can be formulated to be either flexible or rigid, transparent or opaque, fast setting or extremely slow setting, making them appropriate for nearly any use.
  • Hot Melt adhesives, or thermal adhesives, are viscous liquids at elevated temperatures and generally set quickly when cooled. Types include fast set, delayed set and pressure sensitive and common uses are for bookbinding, product assembly and box and carton heat sealing.
  • Laminating adhesives are substances that are used for bonding in thin layers. They come on sheets of release paper that are wound in rolls to be used in lamination presses or applied by hand with a plastic squeegee or hand roller. The liner is then removed from the adhesive.
  • Methacrylates are a newer form of adhesive technology developed to offer superior performance compared to acrylic adhesive, which can be brittle and less reliable. Methacrylates provide good gap fill, excellent impact resistance, flexibility and peel and shear strengths, medium to fast curing, and tolerance of dirty surfaces.
  • Ultraviolet adhesives, or UV adhesives, are cured by exposure to ultraviolet light. These adhesives are commonly used in fiber optics and dentistry.
  • Urethane adhesives bond with a wide range of materials and are tough and flexible at low temperatures but weaken due to high temperatures and contact with moisture.
  • Membrane press adhesives are used in membrane press operation. They are heated to the proper temperature for lamination in the press and then quickly set for the unloading and trimming of the piece.
  • Moisture cure adhesives react with moisture in the air or the bonding substrate to form a cured polymer layer with high strength. Silicone and polyurethane are the most common.
  • Polyurethane adhesives come as two-part formulas or pre-mixed, which need to be mixed very well to give the best quality tough yet flexible bonds that they can. They can form strong bonds to most materials and are more flexible than epoxies.
  • Thermoset adhesives can not be softened with heat once they are set. Thermoset materials include epoxies, polyesters, silicones, rubbers and polyurethanes.
  • Two-part adhesives consist of two or more components that react to become chemically cross-linked. Their higher costs are related to their extremely high bond strengths and exceptional performance, such as epoxies, polyurethanes, acrylics, and silicones.
  • Water-based adhesives, or aqueous adhesives, use water as a carrier or diluting medium. They set when the water evaporates or is absorbed by the substrate.

Abhesive - A substance that is resistant to adhesion and can be used as a non-sticky surface coating for baking tins, frying pans, metal pots, etc. Examples are Teflon and silicone.

Adherend - Something bonded to something else through the use of an adhesive.

Cleavage Strength - How crack resistant a bonded adhesive is when stretched and strained.

Curing - Hardening or solidifying by cooling, drying or crystallization. Also referred to as setting.

Curtain Coating - Covers large areas with a relatively heavy coating of adhesive. Parts are passed through a "waterfall" of coating in an automated conveyor line.

Encapsulant - Can be an adhesive coating that hardens to form a protective layer to prevent degradation of whatever it encapsulates, such as electronic components.

Fatigue Strength - The maximum load an adhesive bond will sustain when subjected to repeated stress.

Impact Strength
- An adhesive's ability to resist shock from a direct perpendicular physical blow.

Peel Strength
- A measurement of the bond strength of an adhesive determined by the force per unit width required to separate bonded materials by applying stress in a "peeling" motion.

Release Paper
- An easily removable protecting and/or carrier sheet for certain adhesives, commonly film and laminating adhesives.

Resins
- Thick, sticky hydrocarbon plant secretions great for varnishes and adhesives.

Roll Coating
- A method for applying adhesive, the simplest form of which is using a paint roller, but usually the coating rolls are part of a roll coating machine that precisely controls layer thickness, does not allow waste and is good for large surfaces at high speeds.

Screen Printing - A method of applying adhesive in specific patterns by way of forcing it through a screen using a squeegee. The size of the screen openings determines the coating thickness.

Shear Strength - How resilient a material, such as a cured adhesive, is to a parallel stress acting upon it, which can cause an irreversible continuous, non-fracturing deformation.

Substrate
- The material surface upon which an adhesive is spread for bonding or coating. More specifically adherend.

Tensile Strength
- A measurement of an adhesive's bond strength based on how resistant it is to tension, being stretched and strained.

Transfer Printing
- A fast method of applying a thin layer of adhesive in a precise pattern, such as on envelope flaps. Usually done using rollers; flat plates can also be used.

Wet Strength
- An adhesive's bond strength immediately after it has been immersed in a liquid under specified conditions of time, temperature and pressure.