The adhesive selected to bond to substrates must be appropriate for the surface energies involved. Surface energy, which ranges from high to low, describes the surface characteristics of a given substrate. The molecular force of attraction between unlike materials determines their adhesion. The strength of this attraction depends on the surface energy of the substrates. High surface energy means a strong molecular attraction, while low surface energy means weaker attractive forces.
Surface Energy Illustrated
A good illustration of the concept of surface energy is found in comparing a waxed vehicle to an unwaxed vehicle. The unwaxed finish has high surface energy, so water puddles on the vehicle. Conversely, the waxed vehicle has low surface energy, so water beads up instead of flowing out.
In the same manner, adhesive on the surface of a material with a high surface energy, flows and “wets out” on the surface. With both high and low surface energy substrates, the area of attachment must be unified, dry, and clean to maximize adhesive contact.
The Challenge of Bonding Low Energy Surfaces
Wetting out is necessary to form a strong bond, so bonding low surface energy substrates can be more challenging.
Low surface energy plastics, or LSE plastics, include such materials as:
- Polypropylene (PP)
- Polyethylene (PE or HDPE)
- EVA (ethylene vinyl acetate)
- Powder-coated paints
These materials are desirable because they are generally soft and have a low melting point. They’re easy to process and mold, even at high volumes, and they’re low-density, which helps with lightweighting. Since low surface energy is a basic characteristic these materials share, they’re all more challenging to bond to versus things like metals, wood, or glass.
Adhesives that are specifically formulated for low surface energy surfaces can solve this issue. Can-Do works with 3M to offer adhesive solutions formulated specifically to address the challenges of bonding to low surface energy materials. Applications for low surface energy adhesives include:
- Building components: signage, lighting, windows, décor
- Transportation: trucking, buses, campers, RVs, light rail
- Outdoor power equipment: brand placards, instrument panels, decoration
- Signs and displays: illuminated signs, restaurants, hotels, retail
- Appliances: brand placards, internal components, small appliances, kitchen/cleaning tools
Low surface energy bonding adhesives allow for the development of lighter, stronger products with improved aesthetics and environmental resistance. Many of these solutions work without the need for primers, eliminating metal fasteners, as well as an extra production step.
Can-Do Tape has been a Master distributor of 3M adhesive tape products for over 30 years. Our professionally trained team is qualified to assist you in determining the right product for your application.