UV-cured acrylic copolymer pressure sensitive adhesive (PSA) having different amounts of crosslinking agents were prepared and adhesion properties were investigated. 0.01 wt% of MMT clay was dispersed in 2-ethylhexyl acrylate (2-EHA)/acrylic acid (AA) monomer mixture containing 0, 0.05, 0.1 and 0.3 wt% 1,6-hexandiol diacrylate (HDDA) for crosslinking. It was investigated that the curing behavior and surface chemistry of PSAs were merely affected by the presence of MMT clays. On the other hand, adhesive properties were influenced by the MMT addition; a cohesive failure was restrained due to improved molecular elasticity even in uncrosslinked acrylic PSAs. However, it was also appeared that combination of 0.3 wt% crosslinking agent and MMT loading might result in the damage of adhesion properties of PSAs possibly due to the lack of chain flexibility. In our studies, it is suggested that the 2-EHA/AA PSAs incorporating 0.01 wt% of MMT and crosslinked with 0.05 wt% of HDDA exhibited the balanced adhesion properties without severe cohesive failure during strip.

UV경화형 2-ethylhexyl acrylate(2-EHA)/acrylic acid(AA) 점착제의 점착특성에 대한 경화제 함량의 영향에 대해 조사하였다. 0.01 wt%의 극소량의 MMT가 도입된 아크릴 단량체 혼합물에 각각 0, 0.05, 0.1, 0.3 wt%의 1,6-hexanediol diacrylate(HDDA)를 경화제로 첨가하고 UV조사를 실시하여 점착제를 제조하였다. MMT 도입이 공중합체의 경화 거동과 점착제의 표면 특성에 미치는 영향은 매우 낮았으나, 점착특성의 경우 MMT의 도입으로 분자 사슬의 유연성이 제한되면서 응집파괴(cohesive failure)가 억제되는 것을 확인하였다. 그러나 0.3 wt%의 경화제가 도입된 점착제는 사슬 경직성이 크게 증가하면서 MMT의 첨가가 오히려 점착특성을 저하시키는 것으로 추측되었다. 결과를 토대로 2-EHA/AA 점착제의 경우 0.05 wt%의 낮은 함량의 경화제와 극소량의 MMT의 도입이 박리 시 응집파괴 없이 균형적인 점착특성을 부여하는 것으로 판단된다.

Keywords: UV radiation curing; pressure sensitive adhesive; acrylic copolymer; montmorillonite; adhesion properties.