Effect of several factors on the mechanical properties of pressure-sensitive adhesives used in transdermal therapeutic systems

The effects of coating thickness, type of adhesive and type and concentration of enhancer on the mechanical properties of two acrylic pressuresensitive adhesives (PSAs) were investigated using a 2 factorial design and an optimization technique. Sixteen formulations containing 0% or 10% of either caprylic acid or methyl laurate in two different PSAs. namely Duro-Tak® 87-2196 and Duro-Tak® 87–2097, were prepared. The adhesive properties of these laminates were evaluated by applying the 90° Dynamic Adhesive Strength Peel Test (90° DASPT) and 180° Release Liner Peel Test (180° RLPT). Coating thickness, concentration of enhancer, and type of adhesive did affect the 90° DASPT. For the 180° RLPT, the most significant factors were coating thickness and concentration of enhancer, with a strong interaction observed between the two. Coating thickness and concentration of enhancer were also used to create mathematical models that correlated these factors with the mechanical properties of the PSAs. For this purpose the optimization technique 32 was applied. It was found that the correlation of the above factors can be adequately described with polynomial equations, which can be used for predicting the mechanical properties of the laminates containing the above PSAs and methyl laurate (0%–10%).