When a company aims to manufacture hundreds of thousands or even millions of units annually, fully automated production and short cycle times are essential. In practice, this is achieved by exposing adhesives to light, enabling them to cure completely in a very short time. Other curing methods, such as heat or humidity, can also be used, hence the distinction between light- and dual-curing adhesives.

Light- and dual-curing adhesives

Light-curing adhesives require at least one fully transparent substrate, such as glass, polycarbonate (PC), or polymethyl methacrylate (PMMA). Only then can light reach the adhesive to initiate the curing process.

Dual-curing adhesives are used when shadowed areas are present in the bonding process. These are regions where light cannot reach the adhesive once components are joined, because the components are either partially transparent or not at all. Here, curing cannot be initiated by direct light exposure, necessitating an additional curing method.

What is pre-activation?

Even when shadowed areas are present and there is no sufficiently visible fillet, the basic principle of light curing can still be utilized. In adhesive technology, a fillet is the adhesive situated between two joining partners.

In such cases, users can turn to preactivatable adhesives like DELO KATIOBOND. What sets preactivation apart is that the adhesive is exposed to light immediately after dispensing, but before joining components. It is first applied to the initial component and then illuminated for a few seconds. This exposure initiates the cross-linking of the adhesive.

After joining components and adjusting to their precise position, the adhesive cures to its initial strength within minutes without additional light. From this point, the assembly can be further processed without any shifting of the joined substrates. The adhesive reaches its final strength within 72 hours without any additional process steps. For dual-curing adhesives like DELO DUALBOND, the curing process can be further accelerated using heat or moisture.

Advantages of pre-activating adhesives

In modern industry, efficiency and reliability are paramount. Pre-activation allows the precise control of adhesion and cross-linking, ensuring consistent quality while reducing costs. Shortening open time becomes increasingly important, enabling faster processing.

• Improved Adhesion: Pre-activation enhances adhesion between different materials in shadowed areas and reduces the risk of joint failure. Pre-activation triggers a targeted initial reaction in the adhesive, enabling uniform and complete cross-linking, which contributes to the strength and durability of the bond.
• Process Efficiency: Stronger adhesive bonds, unachievable without pre-activation, allow for the reduction of mechanical fasteners, increasing process efficiency by saving time and material, and offering structural benefits.
• Cost Reduction: More precise adhesive curing reduces production errors. Lower scrap rates and rework lead to savings in material and operational costs. Usage of pre-activatable adhesives can also lower curing energy requirements, reducing overall manufacturing costs.
• Consistent Quality: Preactivation ensures reproducible results, guaranteeing that every produced unit meets the same quality standards.
• Control of Open Time: The choice of adhesive can influence open time. By shortening open time, production processes can be accelerated, leading to shorter cycle times in manufacturing.

Overall, preactivation contributes to optimized manufacturing, providing both economic and technical advantages.