Epoxy Adhesives

Epoxy adhesives are chemical compounds for joining components. They require clean surfaces compatible with the adhesive. Epoxy resins exhibit high strength and low shrinkage during cure. Epoxy adhesives are widely used for their toughness and resistance to chemical and environmental damage. While most epoxies are two-part adhesives cured at room temperature, some thermally cured or thermoset one-part epoxies systems are available. Depending on the formulation, epoxy resins are used as potting agents, resin binders in fiberglass construction, electrical conductors and various structural bonding applications.

Epoxy adhesives are available in a wide range of chemical compositions, which allow for a number of different setting styles. These setting styles include single component setting, dual component setting, thermosetting, and radiation curing, which includes UV, EB and visible light curing. Single component epoxy adhesives consist of one resin that hardens by reaction with surface moisture, a surface applied activator-primer, or through the application of heat. Dual or multi-component adhesive or sealant systems consist of two or more resins or a resin and a hardener, crosslinker, activator or catalyst that when combined react and cure into a polymerized compound or bond. Two component epoxy adhesive systems are mixed and then applied. 

Thermoset epoxy adhesives are crosslinked polymeric resins that are cured using heat or heat and pressure. Cured thermoset resins do not melt and flow when heated, but they may soften. Phenolic, melamine and urea formaldehyde resins are thermosetting epoxy adhesives that offer strong bonds and good resistance to high temperatures. Vulcanization is a thermosetting reaction involving the use of heat and/or pressure in conjunction with a vulcanizing agent, resulting in greatly increased strength, stability and elasticity in rubber-like materials. RTV silicone rubbers are room temperature vulcanizing materials. The vulcanizing agent is a crosslinking compound or catalyst. Sulfur is the traditional vulcanizing agent used with natural rubber. 

Silicones use moisture, acetic acid and other compounds as curing agents. UV or radiation-cured epoxy adhesives use ultraviolet light, visible light or electron bean irradiation to initiate curing, which allows a permanent bond without heating or excessive heat generation. One disadvantage of UV curing adhesives is the requirement that one substrate is UV transparent. Some UV resin systems employ a secondary curing mechanism to complete curing of adhesive regions shielded from the UV light. EB curable epoxy adhesives use electron beam radiation (EB) to cure or initiate curing. The electron beam can penetrate through material that is opaque to UV light.

• Preface
  In the first edition of this book, I tried to summarize the experiences, information, values, successes, and disillusions that I had experienced with adhesives or sealants during the first 30 years of...
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• The glued together car body
  Recent advances in adhesive chemistries bring new possibilities for automotive structural joints. Comparison of the Betamate toughened epoxy (bottom) to a brittle adhesive (top) and to spot welds...
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• Filled UV Curable Epoxy Provides Low CTE For Electronic Potting and Encapsulating
  Low coefficient of thermal expansion (CTE) epoxies play an important role in the engineering and construction of electronic circuit boards as well as having great adhesive properties for other...
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Part Numbers for Epoxy Adhesives