Preparation and properties of UV cation-initiated self-crosslinking acrylate pressure-sensitive adhesive without reactive diluent

Abstract

The aim of this paper is to synthesize a UV-initiated self-crosslinking epoxy acrylate pressure-sensitive adhesive (PSA) without reactive diluents. The monomers butyl acrylate, 2-ethylhexyl acrylate, and glycidyl methacrylate (GMA) and functional monomers acrylic acid (AA) and hydroxyethyl methacrylate were used as raw materials. Dodecyl mercaptan was used as a chain-transfer agent, and benzoyl peroxide (BPO) was used as an initiator for free radical polymerization in the synthesis of an acrylate prepolymer containing epoxy groups. When a cationic UV initiator was added, the system showed the characteristics of a nonreactive diluent and emitted a faint odor. A self-crosslinking epoxy acrylate PSA was obtained by coating at room temperature and UV light initiation. The effects of AA and GMA dosages, photoinitiator dosage, and curing time on the product's properties were investigated. Viscosity was characterized with a rotary viscometer, whereas the structure, glass transition temperature, and thermal decomposition were characterized through Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis, respectively. Results showed that the PSAs containing 3.5 % AA, 12.5 % GMA, and 2 % photoinitiator 6976 and subjected to 40 s of curing time had the best overall performance, with a loop tack of 11.1 N/25 mm, 180° peel adhesion of 14.5 N/25 mm, dynamic shear strength of 9.2 N/12 mm × 12 mm, and good heat resistance at 80 °C for 4 h without adhesive loss after peeling. A novel self-crosslinking PSA glue was successfully prepared by introducing epoxy groups into the molecular chains of prepolymers and controlling the viscosity of the prepolymers with a chain transfer agent. These procedures effectively remediate the shortcomings of current acrylate PSA glue, which contain active diluents, produce irritating odor, and undergo oxygen inhibition polymerization, offering great prospects for industrial applications.