Interview: “Adhesives are becoming the preferred method of bonding”

Adhesives continue to replace mechanical fasteners in a variety of assemblies, says Brendan M. Cullinan, the technology director of coatings and construction at Brenntag North America. Here, he shares his insights into current trends and his outlook on bio-based adhesives.

What are current trends for adhesives?

Brendan M. Cullinan: Adhesives continue to replace mechanical fasteners for all kinds of assemblies, fast becoming the preferred method of bonding. Large-surface-assembly adhesives and laminates are now designed to encompass the full surface area, remain malleable when dry, and bond rapidly without the need of fixing-in-place. Adhesives are being formulated equally in water-borne and solvent-borne systems and are more popularly made into industrial-strength films and tapes. These industrial, automated adhesive/tape applications are replacing manually applied adhesives, leading to lower production and labor costs. Improved cartridge designs have enabled two-part adhesive to be applied automatically with precise blend ratios and vigorous mixing. The demand for lighter-weight vehicles continues to grow, with their versatile, high-performance 2K adhesive systems that meet rigorous performance standards. Adhering dissimilar composite and metallic materials remains a challenge because of the need to achieve both bond strength and thermal expansion, but higher-performance systems have met the performance requirements.

Brendan M. Cullinan

Technology director of coatings and construction, Brenntag North America

What functionalities do customers want?

Cullinan: With the advancements in application equipment technology, two-part epoxies and urethanes continue to replace conventional welds and standard adhesives in higher-performance applications. Also, the continual demand for increased performance calls for elaborate two-part formulations that withstand the fatigue commonly seen with mechanical fasteners and standard adhesives. Epoxy-curing agents provide a wide performance latitude (flexibility, bond strength, heat resistance, etc.) for epoxy-based adhesives. In urethanes, the performance latitude is driven by the base polyol design and functionality.  

What is the outlook for bio-based adhesives?

Cullinan: The demand for bio-based adhesives continues to slightly outpace the market growth for conventional adhesives, specifically in construction, woodworking, joinery, and all segments of packaging. Soy-based adhesives are by far the market trend leader, replacing phenolic- and urea-formaldehyde adhesives in construction applications that seek LEED certification. Solenis has been the market leader with their “Soyad” technologies, addressing the demand for lower-formaldehyde and zero-formaldehyde emitting applications. This remains a predominantly Western European market but is beginning to trend more in North America. Also driving new application requirements for bio-based adhesives is the boom in Asia’s residential, modular-construction industry. Confined spaces require nil-formaldehyde emitting systems and are being met with higher performing bio-based adhesives.