PSA and laminating adhesives

Laminating adhesives The cross linking achieved by radiant energy enhances the temperature, solvent and shear resistance of hot-melt adhesives with limited effect on critical adhesion properties such as tack and peel. Hot-melt adhesives, especially block copolymers, are also easily cured by EB and UV radiation. These hot-melt adhesives are used as laminating adhesives. 

PSA adhesives A significant use for radiation curing is the advancement or curing of pressure-sensitive adhesives. High solid EB and UV curing liquid adhesives are being formulated from a variety of resins and elastomers. Such adhesive compositions include acrylics, blends of acrylic monomers with elastomers, polyesters and other compositions. These products are primarily used as pressure-sensitive adhesives. 

Overview of radiation-curable adhesives in packaging applications 

The properties that determine whether a product can be labelled as a pressure sensitive adhesive are tack, peel and creep. Tack is the property related to bond formation. Peel defines the tension or force necessary to remove the adhesive tape. Creep is the property describing the flow characteristics of the PSA. Formulators need to be aware of any factors that can directly affect these three properties such as temperature, aging, film thickness, cure rate and post-cure parameters. There are also several formulation variables - these include oligomer selection, tackifier addition, monomer structure, molecular weight and glass transition - that directly impact tack, peel and creep. 

The development of PSAs has concentrated around rubber-based formulations with the inclusion of resin esters or C-5 and C-g hydrocarbon resins as tackifiers - those resins that enhance the sticky feeling of PSAs. 

---

Pressure sensitive adhesives (PSAs) and laminating adhesives are the two major growth areas for UV/EB applications in adhesive formulations. The field of UV/EB pressure sensitive adhesives is growing steeply at around 25% annually and growth is likely to be accelerated in the near future. 

---