Ancamine® 2337M - a latent curing agent designed for low temperature cure epoxy adhesives

For heat-cured structural epoxy adhesives, particularly one-component (1k) systems, curing temperature plays a crucial role. The industry is increasingly looking for curing agents that allow curing at temperatures within the 70 - 80 °C range. At the same time one-component systems are expected to demonstrate long shelf-life stability at ambient temperatures prior to use.

The electronics industry uses a broad range of different materials that require reliable bonding to each other. Some of these materials are heat-sensitive and need protection from higher temperatures. As a result, there is a growing demand for high- performance adhesives such as 1K epoxy adhesives that can cure effectively at temperatures well below 100 °C.  Lower curing temperatures not only ensure the integrity of heat-sensitive materials but also contribute to save energy and cost savings.

While the need for a long shelf life and fast curing at low temperatures may seem contradictory, Evonik has developed Ancamine® 2337M to meet these challenges without compromising the typical properties of epoxy systems. Ancamine® 2337M is an amine-based curing agent tailored for low-temperature curing applications, like electronics that remain stable under ambient conditions, ensuring extended shelf life and ease of handling. Upon mild thermal activation at a minimum of 70 °C, it initiates a rapid curing process, resulting in robust mechanical properties and excellent adhesive properties.

The new Ancamine® 2337M is an optimized version of Ancamine® 2337S, which is well-regarded for its low temperature performance. However, its use has been limited due to an unfavorable labeling associated with the exploding chest (GHS 08) symbol. To address this issue, Ancamine® 2337M has been developed as a non-toxic successor that does not carry this hazard classification.

Ancamine® 2337M retains the excellent product properties of Ancamine® 2337S, ensuring that users can expect the same reliable performance. Key attributes such as particle size and reaction profile, have been preserved, guaranteeing seamless integration into existing processes without requiring adjustments or retraining. 

When Ancamine® 2337M is cured with liquid epoxy resin (EEW=190) at elevated temperatures of 80 °C, 100 °C ,120 °C and 120 °C for 30 minutes, the curing agent demonstrates an increase in glass transition temperature (Tg) with rising curing temperatures, reaching a maximum Tg of 102 °C, as shown in the following graph.

Fig. 1: Change in glass transition temperature upon heating

After mixing Ancamine® 2337M with the resin followed by degassing, the viscosity of the formulation was measured at room temperature. Subsequently, the formulations were stored at 42 °C (108 °F), and their viscosities were assessed (after allowing them to equilibrate to room temperature) every week. The formulation based on Ancamine® 2337M demonstrated stable shelf-life conditions for over four weeks at 42 °C.

More detailed information on the product can be found in the table below and the corresponding technical data sheet.