Abstract:

Series polyacrylate copolymers of THFMA-10, THFMA-20 and RGMA-20 were obtained by free radical polymerization using rosin-based glycidyl methacrylate(RGMA) and furfural-based monomer tetrahydrofurfuryl methacrylate(THFMA) as hard monomers and oil-based monomer lauryl methacrylate(LMA) as soft monomers. Semi-interpenetrating crosslinked network photocuring pressure-sensitive adhesive was prepared through photocuring reaction. The structure of the photocurable pressure-sensitive adhesive was characterized by infrared spectroscopy(FT-IR) and gel permeation chromatography(GPC), and its thermal properties, ultraviolet ray(UV) absorption properties, mechanical properties and rheological properties were analyzed. The results showed that the relative molecular weight(M_n) of the three copolymers was between 40 000 and 60 000, and the dispersion index(PDI) was between 2 and 3. The influence of M_n on the adhesion properties of the pressure-sensitive adhesive was negligible. FT-IR analysis indicated that the photocurable pressure-sensitive adhesive was successfully prepared. The DSC analysis results showed that the interpenetrating cross-linked network had good compatibility with the copolymer. Triethylene glycol diacrylate(TPGDA) was used as crosslinking agent, and the elasticity and cohesion of acrylate copolymer were improved significantly after cross-linking photocuring with 5% of TPGDA. Compared to THFMA, the molecular chain rigidity of the pressure sensitive adhesive obtained by RGMA monomers was higher. TG analysis showed that the thermal stability of the pressure sensitive adhesive was obviously improved after photocuring. The UV absorption performance of the pressure-sensitive adhesive prepared with RGMA as the hard monomer was better than that of THFMA, and it had more advantages in the application of UV protection. Compared with the bifunctional TPGDA, the mechanical properties of the photocurable pressure sensitive adhesive prepared by the tri-functional crosslinking agent pentathritol tetraacrylate(PETA) were significantly improved. The RGMA-based copolymer was added with 9% crosslinking agent PETA, which could effectively balance the initial adhesion(12.34 N), 180° peel strength(264 N/m) and adhesion properties(adhesion time 24 h). The energy storage modulus(G′) and loss modulus(G″) of the photocured pressure-sensitive adhesive increased with the increase of frequency. The structure of the photocured semi-interpenetrating network improved the performance of the pressure-sensitive adhesive. The THFMA-10 series of pressure-sensitive adhesive met the Dahlquist critical boundary before and after photocuring, indicating good pressure-sensitive performance.

Key words: lauryl methacrylate, tetrahydrofurfuryl methacrylate, rosin based monomer, UV curing, semi-interpenetrating crosslinked networks