Huntsman ARALDITE 420 A/B Structural Epoxy Adhesive for Metal and Composite Bonding

ARALDITE 420 A/B Structural Epoxy Adhesive Performance

Huntsman identifies ARALDITE 420 A/B as a high-strength and high-toughness structural adhesive with very high shear performance at temperatures up to 70°C and good peel strength. The cured system is also designed to resist moisture, water, chemicals, heat, and ultraviolet exposure. This combination is valuable where bonded assemblies experience vibration, impact, temperature changes, outdoor conditions, or long-term mechanical loading.

The mixed adhesive is a dark-green paste with a typical specific gravity of approximately 1.1 to 1.2 and viscosity of about 35 to 45 Pa·s. Its consistency supports controlled application onto flat, vertical, and irregular surfaces while helping maintain a uniform bond line. Huntsman lists a hardener-to-resin ratio of approximately 0.4 by weight, commonly expressed as 40 parts hardener for every 100 parts resin.

Metal, Honeycomb, and Composite Bonding Applications

ARALDITE 420 A/B Structural Epoxy Adhesive can bond aluminum, steel, other metals, glass-reinforced plastic, sheet molding compound, composites, thermoplastics, plywood, and wood after suitable preparation. Typical uses include sandwich panels, honeycomb structures, inserts, ferrules, aluminum or composite edge members, joining strips, frames, hinges, doors, seats, floors, roofs, partitions, HVAC assemblies, boat decks, hulls, rail components, and aerospace structures.

The adhesive is particularly useful for bonding inserts and edge members within metallic and non-metallic honeycomb sandwich structures. It can also support cut-and-fold fabrication of composite components. Cartridges with static mixers simplify metering and mixing, while bulk packages can support larger production systems. The final process should be validated for joint design, substrate grade, service temperature, chemicals, and environmental exposure.

7 Benefits of ARALDITE 420 A/B Structural Epoxy Adhesive

• High shear strength: Supports demanding structural assemblies and elevated-temperature loading.
• Good peel performance: Helps resist edge lifting and mixed-mode mechanical stress.
• Tough cured bond: Provides resilience under vibration, impact, and repeated movement.
• Multi-material adhesion: Bonds metals, honeycomb, composites, GRP, SMC, wood, and selected plastics.
• Room-temperature curing: Allows production without mandatory high-temperature ovens.
• Environmental durability: Offers moisture, water, chemical, heat, and UV resistance.
• Flexible packaging: Available in cartridges and bulk formats for different production volumes.

Mixing, Working Life, and Application Guidance

Degrease all bonding surfaces and remove oil, grease, dust, dirt, moisture, and loose contamination. Huntsman recommends acetone or a suitable proprietary degreasing agent and advises against alcohol, gasoline, or paint thinner for this preparation. Stronger and more durable bonds can be achieved by mechanically abrading or chemically etching the degreased surfaces, followed by a second cleaning step.

Mix both components until the colors are completely blended and no streaks remain. Automatic mixing and dispensing equipment may also be used. At 25°C, the approximate usable life is two hours for a 50 g mix and one hour for a 100 g mix because larger masses generate more reaction heat. Using a shallow container can help extend working time.

Apply the mixture directly or with a spatula to the prepared joint surfaces. Huntsman indicates that a bond-line thickness of approximately 0.05 to 0.10 mm normally provides the greatest lap-shear strength. Assemble and clamp the parts promptly, using even contact pressure across the joint while the adhesive cures.

Curing and Elevated-Temperature Performance

At 25°C, the adhesive typically gels in two to four hours and reaches sufficient cure for handling after about five hours. It develops approximately 90% of full strength after four to five days and reaches full room-temperature strength after one to two weeks. This gradual cure profile gives production teams useful assembly time for larger structures and complex components.

Heat can accelerate curing. Four hours at 50°C or one hour at 120°C can provide full strength under the manufacturer’s reference conditions. A post-cure at 70°C can improve shear performance, particularly when the completed assembly will operate at elevated temperatures. Heating times should begin after the adhesive bond line reaches the required temperature.

Storage, Safety, and Official Resources

Store both components in their original sealed containers according to the current product label and safety documentation. Huntsman lists storage for up to 30 months at 18°C to 40°C under the stated conditions. Protect the resin and hardener from contamination and never return mixed or dispensed material to the original containers.

Review the official Huntsman ARALDITE 420 A/B product page and the official ARALDITE 420 A/B technical data sheet page for current specifications, processing instructions, safety information, and regional availability.

Explore our structural epoxy adhesives for additional high-strength bonding products. Browse our composite and honeycomb adhesives for aerospace, rail, marine, sandwich-panel, and industrial applications. Contact our sales team for quotations, package availability, technical documents, mixing equipment, samples, and export support.