Long Working Life Adhesives

The working life of a two-part epoxy system is the time frame after mixing that the operator can properly dispense and handle the compound before it sets up and is considered no longer workable.

A product with a long working life at room temperature would mean that it gels or sets up slowly. This is particularly useful in applications where a large amount of the product (such as quart or gallon) needs to be mixed at a time. Therefore, in applications where the bonding area or potting volume is relatively large, such products can be utilized.

Some products offer an “unlimited” working life at room temperature. Typically, these are one component, heat curable epoxy chemistries. These systems can be formulated to not gel or cure at room temperature, while offering a quick cure at elevated temperatures. It must be noted that although these systems provide an unlimited working life at room temperature, they do not automatically qualify as being suitable candidates for potting applications, since many such products can be exothermic in thick sections. Therefore, a range of factors need to be taken into account while selecting such compounds, and based on the handling and processing constraints, as well as the operating conditions in the final device, the product choice can vary.