When it comes to selecting the right sandwich panel adhesives, a number of factors need to be considered to ensure that the final product meets all of the required specifications.
Adhesion and Bond Strength
The most crucial factor to consider when bonding materials is the strength of the bond between the adhesive and gluing material. In applications where high strength is necessary, a thermoset adhesive that fails within the core material rather than the adhesive or cohesion is typically the best option. However, it’s also important to avoid using a high-strength material when it’s not necessary because it can cause the part to become excessively rigid. Therefore, it’s important to determine the strength requirements beforehand to ensure the appropriate adhesive is used.
It’s important to determine the strength requirements beforehand to ensure the appropriate adhesive is used
Processing Parameters
After determining the required strength, it’s crucial to consider the processing parameters of the materials used.
Depending on the dimensions of the panel and the required time for gluing and assembling the panel, selecting adhesive with the appropriate open time is necessary. Since the open time of the adhesive is directly related to the required clamping time, to achieve high production productivity with the shortest clamping time, it is necessary to determine the adhesive's shortest open time.
The appropriate open time of adhesive is a key characteristic that affects the speed of panel production and production capacity.
Flame Resistance Requirements
When selecting an adhesive for bonding the skin to the core in shipbuilding, it is crucial to consider the flammability requirements set forth by the International Maritime Organization (IMO) Resolution. The IMO requires that all materials used in shipbuilding meet specific fire safety standards. Therefore, the adhesive chosen must comply with the IMO Resolution’s requirements for flame, smoke, toxicity, and other testing.
It is worth noting that compliance requirements may vary depending on the type of vessel being built, such as passenger ships, cargo ships, or offshore drilling platforms. Furthermore, the flammability of the skin itself must also be taken into consideration when selecting the adhesive. If a skin with lower heat resistance is selected, choosing a flame retardant adhesive that meets all the IMO Resolution’s compliance standards is even more critical.
When choosing a skin to core adhesive, it’s important to consider the flammability requirements of the application.
Foaming Effect
One can choose between one-component and two-component polyurethane adhesives when bonding sandwich panels. One-component polyurethane adhesives are easier to use, but it should be noted that they foam during the reaction. The adhesive foaming is advantageous when bonding porous materials such as mineral wool or wood, as the adhesive consumption per m2 is reduced due to the foaming. However, when bonding very thin materials or closed smooth surfaces such as metal or plastics, the foaming adhesive can cause irregularities in the form of bubbles on the panel's surface. For bonding thin non-porous materials such as aluminium, PVC, HPL, etc. We recommend using two-component polyurethane adhesives that do not foam during the reaction. One-component adhesive for lower adhesive consumption, two-component adhesive for smooth surfaces.
One-component adhesive for lower adhesive consumption, two-component adhesive for smooth surfaces.
Quantity and Thickness
The quantity and thickness of the adhesive are also important factors to consider. Too much adhesive can weaken the bond line, while too little adhesive can cause issues such as adhesive failure from the honeycomb or foam during adhesion testing. Adhesive thickness is also important to the flammability of the system, as thick bond lines can become softened during flammability testing and cause system failure.
By considering these factors, you can choose the best sandwich panel adhesives for your specific application, ensuring that they will perform as expected and meet your requirements.
