| abstract |
The present invention relates to a pressure-sensitive-adhesive copolymer comprising copolymerizable photoinitiator monomers such as benzoin compounds, acyloin compounds, and mixtures thereof; low-glass-transition-temperature monomers; and multifunctional monomers. The invention also provides a process for the preparation of such copolymers. The actinic radiation cure of the polymer is performed with light at about 240 to about 410 nm wavelength, a light intensity of about 6 to about 10 kWatts/m2, and at a temperature of about 45 °C to about 125 °C, under aerobic conditions. The resultant pressure-sensitive adhesives exhibit cohesive strength and high-temperature shear strength which, in a static shear test, does not fail after several thousand minutes; a tack performance of about 300 to about 500 N/m; a peel adhesion performance of about 550 to about 650 N/m; a shelf-life at room temperature of more than about 10 months, with little or substantially no increase in the viscosity of the polymer; and a hot melt pot-life at 100 °C of at least 10 days, with little increase in the viscosity of the polymer. |