When it comes to making the right decision, it’s advised to gather as much information as you can, which especially holds true for adhesives, where even one minute detail can change the entire situation.
Selecting the best adhesive for a specific application can be challenging, which requires a good understanding of many variables as well as various types of chemistries with different capabilities. Selecting the correct adhesive is the key to getting the best results. Again when it comes to choosing the right adhesive for your project, everything boils down to the application it will be used for and the environment in which it will be applied.
Here are some factors to consider when selecting an adhesive:
Type of surface the adhesive will be applied to- In your bid to finding the right adhesive, it is crucial that you know a little about the materials you will be attempting to bond, as adhesives attach to the surfaces of two substrates. Surface condition must be considered in terms of roughness, smoothness, coated, uncoated, cleanliness, flexibility, porosity, and size of the part.
It is wise to do a little research into the substrates you are hoping to bond prior to researching your adhesive, as not every adhesive will work on every surface. For example, pressure sensitive adhesives (PSAs) stick to most surfaces, hot melt glue sticks and bulk hot melt are excellent at bonding porous materials such as paper, cardboard, wood, as well as some plastics, and laminating adhesives are extensively used in flexible packaging (the process involves joining together two or more packaging webs- webs can be in the form of films, papers, or aluminum foils- using a bonding agent). The rise in demand for flexible packaging has seen noticeable growth in demand for the market of laminating adhesives.
Temperature the adhesive will be exposed to during use, distribution and storage- Environmental conditions like temperature impacts how an adhesive will cure and perform over long periods of time. The temperature the adhesive will endure or be exposed to during use, distribution and storage is a vital consideration when it comes to choosing the right adhesive, since even minor changes in temperature can largely affect cure speed and storage life of adhesives.
For example, silicon adhesives are ideal for marine or plumbing applications due to their higher degree of flexibility as well as good resistance to higher temperatures.
Strength & Tack- This is an extremely important consideration when choosing an adhesive. Adhesive strength is the interfacial strength between adhesive and substrate, but not the only factor to create an effective bond. The adhesive must bond to the surface of the substrate to increase the likelihood of the bond to be successful.
For example, for laminating, water-based adhesives are commonly used as an alternative to resins. On the other hand, hot melt adhesives allows for re-positioning during assembly as they can be melted or softened repeatedly by heat, or set by cooling.
Exposure of adhesive to high humidity during end use, application or distribution- Adhesives tend to become more foamy in appearance or softer in quality with exposure to excessive humidity. Some adhesives may remain unaffected by humidity within a certain range, but the bond strength is likely to be negatively impacted if condensation forms on top of a substrate.
Adhesion performance is affected by both moisture and humidity. We can cite acrylic adhesives as an example in this regard, which though have excellent environmental resistance, but are more prone to moisture that affects their application and durability aspects.
Experts strongly recommend adhesive testing prior to production or purchase, otherwise it’s still uncertain whether a particular adhesive will perform exactly as you need it to.