Influence of Selected Photoinitiators on Important Properties of Photoreactive Acrylic Pressure-Sensitive Adhesives

Photoreactive solvent-borne pressure-sensitive adhesives are not commercially available in the market. The reason for it is that the UV-initiated crosslinking has sense only in the case of solvent-free self-adhesive systems. Investigations conducted in Institute of Chemical Organic Technology have shown that the photoreactive solvent-borne acrylic PSA are conventional crosslinked solvent-borne acrylic PSA used as crosslinking agents typical metal chelates as titanium acetylacetonate (TiACA), aluminum acetylacetonate (AlACA) or thermal reactive crosslinker melamine-formaldehyde resin Cymel 303 clear considered. The main purpose of the investigation was to study the influence of diverse photoinitiators on main properties, such as shrinkage, tack, peel adhesion, and shear strength of solvent-based acrylic pressure-sensitive adhesives. The interesting alternative to conventional photoinitiators is unsaturated photoinitiators described in this article. Following unsaturated photoinitiators were used: 4-acryloyloxy benzophenone, 4-acryloyloxyethoxy benzophenone, and 4-acryloyloxybutoxy benzophenone. The influence of the crosslinking agents or crosslinking methods was determined in relation to the reaction time and to the concentration versus adhesion properties. The increase of photoinitiator concentration causes in the decrease of the shrinkage. Increasing the UV dose during the crosslinking of acrylic PSA film leads clearly to better shrinkage resistance. The best results of the lowest shrinkage value of 0.35% were given by using 4-acryloyloxy benzophenone. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 123: 118-123, 2012