What are you bonding to?
Adhesive tape can bond to a wide range of substrates, but due to the varying characteristics such as their texture, porosity, flexibility and surface energy, not all adhesive products are compatible.
To ensure we provide you with a long lasting bonding solution we need to understand the characteristics of your substrates. Below we discuss in more detail, commonly bonded substrates, along with tips on choosing the right bonding product.
Not all plastics have the same properties; some are easy to bond to and some difficult. Where determining the ease of bonding to plastics, they are commonly separated into two categories; high surface energy and low surface energy plastics. Below we discuss these in more detail as well as one other tricky to bond to plastic – PVC.
High surface energy (HSE) plastics
These are, generally, one of the most stable materials to bond to as the adhesive will easily ‘wet out’ creating a secure bond. HSE plastics include Kapton, Phenolic, Nylon, Acrylic, Polyester and Polycarbonate plastics. Where the bond is vertical and the bonded part is heavy, the shear strength of the tape must be considered.
Low surface energy (LSE) plastics
LSE plastics are the opposite of HSE plastics, they can be difficult to bond to as the adhesive does not easily ‘wet out’. They include PVA, Polystyrene, EVA, Polyethylene, Polypropylene and PTFE plastics. The challenges of bonding to a low surface energy plastic can be overcome by selecting a product specially formulated to encourage adhesion to LSE materials. These products include rubber based and modified acrylics which typically offer better adhesion as they are softer and flow (‘wet out’) better. Some materials may require surface preparation to promote adhesion e.g. corona treatment, priming or top coating.
PVC plastics contain plasticisers, an ingredient added to make the plastic flexible and stretchy. Over time the plasticiser molecules migrate from the plastic and are absorbed by the adhesive making it flexible and stretchy. As a result, adhesion is lost, resulting in bond failure. Adhesive tapes are available that have been specifically formulated to resist plasticiser migration; these must be used where bonding to any type of PVC substrate to ensure a long-term bond.
Metals have a high surface energy, meaning the adhesive will easily ‘wet-out’ on the surface to create a secure bond. The type of metal being bonded to will determine the adhesive tape that should be used. This is due to differences in surface textures, treatment finishes, plating and the flexibility of the metal.
Some metals e.g. copper, brass and bronze, are prone to oxidation, even after tape is applied. To prevent the bond being weakened a coating, such as varnish, should be applied to the surface.
We have a wide range of products for adhering to these metals, as well as aluminium, stainless steel, zinc, tin and lead. Ensure surfaces are cleaned with IPA or a surface cleaner and left to ‘flash off’ before applying an adhesive tape.
The most common problem is exposure to UV and subsequent adhesive degradation. A product that has a high UV rating must be selected for both internal and external applications subjected to any UV light.
The potential of shear failure is another common issue, as most entail vertical bonds. This can be avoided by selecting a product with high shear strength.
Another consideration is the surface texture of the glass. If the glass is textured, a thicker and more conformable product should be used. A primer can also be used to enhance the bond strength.
Wood is not an easy substrate to bond to in its natural state as it is porous and contains moisture and sap. Ideally, the wood should be sealed with a coating such as a primer, paint or varnish to provide a uniform surface and a better bonding condition. If bonding to wood in its natural state, an adhesive that is ‘wet’ enough to flow into the wood structure should be used.
Powder coated paint
If the substrate has been powder coat painted, this coating becomes the bonding surface, rather than the substrate. Powder coated paint surfaces can easily be bonded to. The products most suitable are those with good adhesive ‘flow’ and those with initial high tack.
If the powder coating contains silicone, the bond will be compromised as silicone can be extremely difficult to bond to. Where silicones are present, a specialised silicone adhesive tape must be used.
Ceramics can be difficult to bond to as the surface is generally very smooth, which inhibits any ‘flow’ of the adhesive. The naturally ‘cold’ characteristics of ceramic also inhibit the bond. A good solution for this would be to gently warm the surface and to use a VHB material.
Bonding to fabric poses two main issues; the bond can fail if a ‘dry’ type of adhesive is used and, where a double coated tape is used, movement over time can break down the fibres of the material.
The ideal tapes for bonding to fabric include those with a ‘wetter’ adhesive, for better ‘grab’ and initial bond strength and transfer tapes that are flexible enough to move with the fabric.
Foam and rubber
Most foams are easy to bond to. The choice of adhesive tape will depend on whether you are bonding to an open or closed cell foam. Transfer adhesives are recommended for open cell products and both transfer and double coated tapes are suitable for bonding to closed cell foams.
Rubbers are not as easy to bond to as they can have a low surface energy and can contain oils and plasticisers. Over time the plasticiser molecules migrate from the rubber and are absorbed by the adhesive making it flexible and stretchy. As a result, adhesion is lost, resulting in bond failure. To avoid this, rubber can be primed to seal in the plasticisers and promote adhesion, or a tape that is specially formulated to resist plasticisers can be used.