Property modification of a silicone acrylic pressure-sensitive adhesive with oligomeric silicone urethane methacrylate

A silicone acrylic pressure-sensitive adhesive (SPSA) was synthesized using a silicone macro-azo-initiator as an adhesive for low surface energy substrates. The SPSA had a high peel strength value on an SUS (steel use stainless) substrate due to its low surface energy; however, it had very low peel strength values on low surface energy substrates such as PP and PE. In this study, a silicone urethane dimethacrylate (SiUDMA) oligomer was synthesized as a modifier for the SPSA. The SiUDMA had a much lower viscosity and a slightly higher surface energy than the SPSA. The addition of SiUDMA increased the peel strength of the SPSA regardless of the substrate. In the case of the PP and PE substrates, the increase of peel strength with SiUDMA addition was remarkably large when compared to the SUS substrate because SiUDMA significantly reduced SPSA viscosity and improved its fluidity, consequently facilitating the wetting of the rough surfaces of PP and PE. The rough surfaces of PP and PE could also aid the spreading of SiUDMA-modified SPSA and enlarge the interfacial area. On the other hand, UV curing of SiUDMA and the SiUDMA-modified SPSA resulted in a serious decrease in the peel strength on the PP and PE substrates due to the decrease in the fluidity of the SPSA material, but the SAFT of SPSA increased with UV irradiation.