Waterbased Adhesives
Defined

Waterbased adhesives use water as the carrier fluid, with the adhesive particles suspended in water, reducing the adhesive’s viscosity so that it can be applied to various substrates at varying thicknesses. (Ref. 6) Evaporation of the carrier fluid during the set and cure stages typically occurs in large ovens. Evaporation and cure also can take place in the open under ambient, non-thermal conditions. It is important to note that not all waterbased adhesives are 100% solvent-free, but may contain some VOCs as assistants to the water base for proper viscosity or fluid control. Waterbased adhesives have been available since the 1970s. They are formulated from rubber compounds (as the base material), with various additives such as synthetic hydrocarbon resins or pine sap derivatives to increase strength characteristics.

Uses and Properties

Waterbased adhesives are used primarily in packaging and for general construction purposes. (2, 4) Table 2 identifies the sectors and applications in which waterbased adhesives are commonly used.

Water is a relatively high surface tension material, and as a result, waterbased adhesives work well on other high surface tension materials like paper. Waterbased adhesives are best applied in longer production runs, as opposed to batch runs, since waterbased adhesives take longer to equilibrate on the backing material. A longer run results in an increase in the usable end product and ensures a profit on the run. (Ref. 6)

Waterbased adhesives have some limitations that must be recognized. Waterbased adhesives do not work well with backings that have a low surface energy, such as plastic films, metal foils, vinyls and foams. (Ref. 6) Waterbased adhesives also have lower performance characteristics than solvent-based adhesives, including:

• lower peel strength at room temperature
• lower shear strength at high temperatures
• less flexibility in adhesion to a broad range of backings
• lower humidity resistance (Ref. 6)

Continue on to the technical issues page of the Waterbased Adhesives Technology Review.

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