Developing an industrial-strength — but environmentally friendly — adhesive that cures upon exposure to LED lighting was an ambitious undertaking, admits Robert Michaels, vice president of technical sales for Master Bond Inc.

Master Bond's LED401 adhesive is the result of two years of "extensive R&D," Michaels tells New Equipment Digest.

"We experimented with countless formulations to optimize performance properties," Michaels says.

The final product, Michaels explains, is a solvent-free, high-strength adhesive that eliminates the need for expensive UV-cure equipment — and improves worker safety.

NED: What led Master Bond to develop this particular adhesive?

RM: Traditional light-cure adhesives cure under UV light with wavelengths between 250 and 365 nanometers [nm]. Master Bond LED401 was developed to cure under a visible-light wavelength of 405 nm.

This compound cures quickly, requires no mixing and features outstanding performance properties.

LED401 is a solvent-free formulation and has high bond strength to glass, metals, elastomers and many plastics.

NED: How is this product different from similar adhesives currently being offered?

RM: LED401 eliminates the need for expensive UV-cure equipment and improves worker safety. It cures tack-free upon exposure to low-cost LED lamps.

Additionally, it is ideal for bonding thermally sensitive parts-limited heat/IR is emitted. It will bond well to tinted and UV-blocked substrates.

NED: Any particular problems that came up during the development process?

RM: It was difficult to design a tack-free formulation. Also, much effort was placed on developing a product that could be conveniently applied.

Bond strength to similar and dissimilar substrates was carefully analyzed as well as the effects of thermal cycling on bond strength.

NED: What was the length of time from conception to final production?

RM: We conducted extensive R&D to develop this product. We wanted a product that offered superior optical clarity, exceptional electrical-insulation properties, outstanding chemical resistance and [the ability to] cure up to and beyond 1?8 inch thick.

It took over two years of testing and experimentation.

NED: Did cost factors affect the final design of this adhesive?

RM: Master Bond wanted to develop a compound that was cost-effective and would improve productivity. We worked hard to develop a product that featured a fast cure (15 to 30 seconds or less) upon exposure to an inexpensive LED light source.

We experimented with countless formulations to optimize performance properties. Special emphasis was placed on making this product environmentally friendly.

NED: Who do you view as the primary users of this adhesive and how will they benefit?

RM: Manufacturing companies in the electronic, optical, electro-optical, medical, appliance and telecommunication industries.

This compound is easy to apply, requires no mixing, cures at ambient temperatures and provides long-term durability and reliability. It will lower processing costs.

NED: Care to add any other interesting sidelights?

RM: We recently introduced a lower-viscosity version of this product, called LED401LV, and a USP Class VI-approved LED-curable adhesive/sealant, called LED403Med.