Surface Tension

Surface tension describes the energy that acts on a material surface and determines how well adhesives or printing inks adhere. It is a key factor for label production: A permanent bond is only created if the labeling film and the labels are matched to the surface tension of the substrate to be labeled. This is how manufacturers ensure functional label solutions for demanding applications, for example in automotive, medical technology and chemicals.

To classify materials, the surface tension is divided into three areas:

LSE (Low Surface Energy, 18–35 mN/m)

Materials with low surface energy make adhesion more difficult and require specially developed adhesives. Typical examples are:

• PTFE (Polytetrafluoroethylene / Teflon)
• Silicone (SI)
• Polypropylene (PP)
• Polyethylene (PE) including HDPE (High Density) and LDPE (Low Density)
• PMMA (Polymethyl methacrylate)
• Epoxy resin (EP)
• Polystyrene (PS)
• Polycarbonate (PC)
• Polyamide (PA)
• Polyurethane (PUR/PU)

MSE (Medium Surface Energy, 37–70 mN/m)

This includes materials with medium surface energy, where adhesion is more successful, but adapted adhesives are still required:

• TPU (Thermoplastic Polyurethane)
• PVC (Polyvinyl chloride)
• PVB (Polyvinyl butyral)
• PET (Polyester)
• PPE (Polyphenylene ether)
• PES (Polyethersulfone)
• PI (Polyimide)
• GPK (Glass, Porcelain, Ceramics)

HSE (High Surface Energy, 290–2000 mN/m)

Materials with high surface energy generally offer very good conditions for adhesion:

• Glass
• Lead (PB)
• Aluminum (AI)
• Copper (CU)
• Iron (FE)
• Steel / Stainless steel (VA, Niro, Inox)