Adhesion Performance and Recovery of Acrylic PSA with Acrylic Elastomer (AE) Blends via Thermal Crosslinking for Application in Flexible Displays

Abstract

Acrylic pressure-sensitive adhesive (PSA) is used to fix each layer of a flexible display. Acrylic PSA needs to satisfy specific elongation and recovery requirements so that reliability of the flexible display can be achieved. For this reason, we aimed to design an acrylic PSA/acrylic elastomer (AE) blend and to study how some viscoelastic and adhesion properties are influenced by the AE content into the mixed, blended system. Samples were characterized by UV–Vis spectrophotometry for transmittance, texture analysis for adhesion performances, and dynamic mechanical analysis (DMA) for recovery and viscoelasticity. When acrylic PSA/AE was simply blended, the adhesion performance changed due to the influence of the long molecular chains of AE. Based on this result, the AE content was fixed at 10 wt %, and acrylic PSA prepolymer was crosslinked at different concentrations of crosslinking agent. Peel strength and probe tack decreased as the concentration of crosslinking agent increased, as reported in previous studies. On the other hand, as the content of the crosslinking agent increased, recovery characteristics were improved. Additionally, as the content of the crosslinking agent increased, the storage modulus also increased, although the glass-transition temperature was not affected. According to these findings, we successfully proved the possibility of using AE to adjust adhesion performance and recovery of acrylic PSA for designing flexible displays.

Crosslinking of Pressure-Sensitive Adhesives with Polymer-Grafted Nanoparticles

“…Furthermore, PSAs are only useful between the glass transition ( T g ) and melting ( T m ) points of the elastomer itself, as temperatures below T g render the material too brittle, and temperatures above T m cause the material to flow and lose adhesion. Crosslinking of the elastomer (such as with acrylic acid (AA) moieties and metal salts) has proven effective at increasing cohesive strength and extending the functional temperature window, but at the cost of adhesive power. − Alternatively, the addition of the nanoscale filler material (e.g., SiO 2 nanoparticles) improves both substrate adhesion and film cohesion for very low filler content (typically <5 wt %) but ultimately degrades performance as the filler content is further increased, limiting the amount to which they can improve PSA properties. − Nanocomposite fillers and surface-modified nanoparticles have more recently emerged as promising candidates for property enhancement, but a great deal of this phase space remains unexplored. − In particular, these nascent strategies are not amenable to rational ab initio design of filler particle parameters, and their use in conjunction with other reinforcement methods (such as crosslinking and entanglement) is underdeveloped. New nanocomposite filler materials capable of engaging in this type of multimodal reinforcement are therefore a critical need in advancing this area of materials research.…”

Combined computational and experimental approach for bio-sourced monomers to design green pressure-sensitive adhesives

“…The lower molecular weight of poly (2-EHA) resulted in relatively less entanglement as compared to poly (AELO) and poly (AEME) which led to the cohesive failure of the former along with lower peel strength. 73 In contrast, AELO has a long alkyl chain triglyceride structure with multiple acrylate functionalities, which forms a more entangled structure after polymerization. Meanwhile, AEME is a long-chain methyl ester with relatively lower acrylate functionalities resulting in less entanglement.…”

Highly Stretchable, Soft, and Clear Viscoelastic Film with Good Recoverability for Flexible Display

“…Acrylic PSAs have been widely used in display, electronics, and automobile industries due to their good optical properties, high weathering resistance, robust adhesion, and facile modification. − Additionally, acrylic polymers can be conveniently prepared by radical polymerization, which is commonly practiced in industry . Acrylic CVF for flexible displays has been previously reported. ,− For example, Park et al . designed rigid-flexible nanoparticles composed of a rigid core and an elastic reactive coil shell, forming linkages with a matrix polymer chain and thereby improving recovery with high adhesion strength.…”