Adhesives

About Adhesives and Adhesive Suppliers Including: Acrylic Adhesive, Adhesives Manufacturers, Conductive Adhesives, Epoxy Adhesives, Epoxy, Hot Melt Adhesives, Industrial Adhesives, Laminating Adhesives, Polyurethane Adhesive, Pressure Sensitive Adhesive, Silicone Adhesive & Ultraviolet Adhesives.

Adhesive manufacturers and adhesive suppliers offer a wide assortment of products for temporary and permanent bonding, encapsulating, laminating and sealing. To buy or have manufactured the most effective adhesive for a certain situation, consider the type of material to which it needs to bond and the type of bond strength necessary for the duration and demands of the application. Searching for the right adhesive can be quite a task because the kinds are so various and new innovations are continuously forthcoming.

Adhesives can come as one-part or two-part formulas. Two-part adhesives consist of two separate components that need to mixed (some come pre-mixed) or applied to separate adherends 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 or loss of water or a different solvent, pressure and lack of oxygen, as in anaerobic adhesives.

Adhesives can have differing setting temperatures ranging from above 212 degrees F to below 68 degrees 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. Adhesives have various setting speeds, some remaining tacky for a certain amount of time allowing parts to be assembled. Adhesives that have residual tack offer repositioning options. Once harden some adhesives can not be softened with heat; these are thermoset adhesives. However, some can be softened due to temperature change or moisture contact, 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. Film adhesives offer a uniform glueline, are activated by heat and/or pressure and come with or without release paper. Laminating adhesives are common film adhesives. A gap filling adhesive can be utilized as a sealant because it does not shrink much when set. Adhesive manufacturers and adhesive suppliers often sell application products such as hot melt glue guns and dispensers. Application methods include spreading with a tool or brush, spraying, dispensing through a nozzle (as in hand-held squeeze bottles, caulking guns or complex air-actuated or electric-actuated nozzles), roll coating, transfer printing, screen printing, curtain coating and application as a solid as with pressure sensitive or heat-activated film adhesives.

Adhesives Types

• 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.

Adhesives Terms

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.