Adhesive for dissimilar materials Research and Development Department of Company K, an automotive parts manufacturer
Develop high-toughness adhesives for automotive parts
Develop high-toughness adhesives
Company K is promoting research and development into replacing steel with carbon fiber reinforced plastics (CFRP and CFRTP) and plastics as a way to reduce the weight of automotive parts. In order to accommodate the change in materials, the company is considering dissimilar material adhesion technology to join different materials such as metal and plastic, but has run into a difficult problem.
Challenges
We tried to improve the toughness of epoxy adhesives but couldn't find a solution...
Company K is focusing on adhesive technology in the development of joining technologies for automotive structural materials, due to the benefits of eliminating gaps and mitigating vibrations. The company decided to focus its development efforts on epoxy adhesives, due to their high heat resistance and excellent adhesion to steel plates. However, while epoxy resins have the advantages of excellent mechanical properties, heat resistance, and water resistance, they are hard and brittle, so it was necessary to impart toughness to the resin by modifying it with rubber or dispersing rubber components as an additive.
Mr. T from the Research and Development Department at Company K said the following:
"One method known to give epoxy resin toughness is to modify the ends with rubber, but this lowers the glass transition temperature, raising concerns about reduced heat resistance. Furthermore, the method of dispersing rubber components as additives into epoxy resin has the problem of variations in physical properties depending on the curing conditions and the state of dispersion of the rubber components. In order to improve the toughness of epoxy adhesives, we approached adhesive manufacturers with whom we have a track record, and conducted repeated collaborative trial production and evaluation."
To improve toughness, adding rubber particles such as nitrile butadiene rubber to epoxy resins has been shown to have a toughening effect, but this results in a decrease in adhesive strength at high temperatures (100°C to 120°C).
Unable to find a method to impart toughness that would achieve the development goal, Mr. T and other members of the R&D department, along with the adhesive manufacturer, were at a loss.
Key Challenges
Epoxy resin has excellent mechanical properties, heat resistance, and water resistance, but it is hard and brittle.
Various methods were considered to impart toughness, but it was difficult to achieve development goals, including adhesive strength.