Synergistic improvement on both the oil-resistance and heat-resistance performance of a single-component acrylic pressure-sensitive adhesive

Abstract

Traditional pressure-sensitive adhesive (PSA) materials are prone to failure under oily and high-temperature environments. Herein, a new series of acrylate copolymers, poly(methoxyethyl acrylate - butyl acrylate - ethyl acrylate - acrylic acid - (N-methoxy acrylamide)), were developed as single-component acrylic PSAs. The oil-resistance and heat-resistance of acrylic PSAs were improved remarkably through three strategies: 1) using the polar monomer, methoxyethyl acrylate (MOEA), to replace the commonly used monomer of 2-ethylhexyl acrylate (EHA), as the dominant ingredient in PSA to increase oil-resistance, 2) innovatively introducing N-methoxy acrylamide (NMOAM) as a new internal crosslinking monomer, thereby maintaining the stability of the PSA system at ambient conditions, while crosslinking with acrylic acid (AA) at high temperature curing conditions to obtain a single-component PSA, 3) owing to the synergistic effects of polarity and crosslinking which occurred during curing process, the oil-resistance and heat-resistance of PSAs enhanced greatly. The molecular weight of the acrylate copolymers and viscosity of the copolymer solutions were regulated by using xylene as a co-solvent to balance the adhesive properties of the acrylic PSAs. Effects of MOEA and NMOAM concentration on adhesive properties were investigated in detail. Results showed that the maximum tack of 12 #, shear strength of >168 h, and 180° peel resistance of 23.47 ± 0.07 N/24 mm could be obtained when 60 wt% of MOEA and 3 wt% of NMOAM were used for the PSA preparation. The obtained PSA tapes were able to maintain excellent adhesive properties even in harsh environments, such as high temperature and oily environment. This work demonstrates that how the comprehensive properties of acrylic PSAs can be improved thereby facilitating their application in the automobile industry, including bundling wire harnesses in car engine rooms or mounting attached parts to tanks.