Universal mix-in adhesive improver

Improved interfacial adhesion to unprimed surfaces


Scientists at the Army Research Laboratory have recently invented a method for improving interfacial adhesion of an adhesive to unprimed substrates as well as an improved adhesive composition. The patent-pending technology is available via patent license agreement to companies that would make, use, or sell it commercially.

Lance Cpl. Daniel Rohrer creates resin glue for composite repairs on CH-53E Super Stallion helicopter equipment. (Vance Hand/Navy)

All adhesives eventually delaminate from the substrates they bond to, and environmental conditions play a major role in determining the time before delamination occurs. Delamination is accelerated by extreme climatic environments like hot or wet conditions. Traditionally, combating this delamination is accomplished by applying a surface primer on the targeted substrates before adhesive application, which costs time.

The new technology from the ARL incorporates the use of adhesive modifiers with particular characteristics with the adhesive to improve adhesion without requiring priming a substrate’s surface. The modifiers include either a non-aromatic polyol with a number of alcohols or a molecule with an ortho-hydroxyl substitution on a benzene ring. The adhesive modifiers may further include a dopamine, a maleimide-dopamine monomer, tris, or derivative.

There is generally no limitation on the adhesive that it may be employed with, and examples include:

  • an epoxy such as DGEBA-based resin
  • a thermoplastic elastomer
  • a thermoplastic urethane or urea

An example modified epoxy has shown about a 50% improvement in lap shear strength for minimally prepared alumina substrates over the baseline epoxy, and a nearly 60% improvement for specimens maintained in hot and wet conditions. The performance of the modified epoxy on the bare alumina substrate is comparable to a substrate prepared with reactive alkoxysilane (aminopropyltriethoxy silane, APTES), which is the industry standard.

These improved adhesives can be used in a variety of fields, including but not limited to sporting goods, automotive assembly, electronic assembly, marine applications, furniture assembly, footwear assembly, and residential and commercial construction applications.

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