Effect of Photoinitiators on Adhesion Properties of 2-EHA/AA PSA

Abstract

Pressure sensitive adhesive (PSA) based on 2-ethylhexyl acrylate (2-EHA)/acrylic acid (AA) copolymer was synthesized using different photoinitiators. Results showed that PSA with Irgacure ® 651 (benzyldimethylketal) and Irgacure ® 184(1-hydroxy-cyclohexylphenyl ketone) proved to be good for adhesion properties. This may be attributed to strong absorption near 350 nm wavelength and also high solubility in monomer mixtures. The addition of Irgacure ® 819, bisacylphosphine oxides as a photoinitiator caused cohesive failure with high loading in a peel test owing to the additional radical formation. It is assumed that the insoluble photoinitiator reacts with oxygene, which may act as a hydrogen donor.

Effect of Crosslinking Agent on Adhesion Properties of UV Curable 2-EHA/AA Pressure Sensitive Adhesive

“…Increasing molecular weight and degree of crosslinking are usually expected to cause a decrease in peel adhesion because these factors may increase the modulus of elasticity and decrease the polymer chain mobility. 3,8,10 The 180 o peel adhesion of the sample without crosslinking agent is highest as shown in Figure 4, but severe cohesive failure leaving visually noticeable residue was happened during stripped similar to the result of probe tack test. It is also noteworthy that compared with the sample without MMT, the introduction of 0.01 wt% MMT effectively restrained the cohesive failure of PSAs.…”

“…In order to raise the T g of major monomer, acrylic acid (AA, T g =106 o C) will be copolymerized with 2-EHA, which may increase peel adhesion at room temperature at moderate peel rate. 8,10 The influence of MMT clays on adhesion properties especially failure mode will be also investigated. It is expected that the nanoscale size and the large specific area of MMT may result in an improvement in the cohesion of polymer molecules.…”

“…It may be considered that intercalated, not exfoliated MMT platelets may hinder the crosslinking process. 10 Adhesion Properties of 2-EHA/AA/MMT Nanocomposite PSAs. In probe tack tests, the tip of a probe is brought into contact with a supported adhesive under low contact pressure for a short time and then pulled way at a fixed rate, followed to the measurement of the peak force of separation.…”