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.

UV-crossinkable pressure-sensitive adhesives (PSA) materials are called, in the adhesives trade photoreactive self-adhesive. UV-crosslinkable PSAs are designed after the UV-initiated crosslinking reaction to stick to almost any surface by a simple contact under light pressure. This special class of adhesives does not undergo any physical transformation or chemical reaction during the bonding process. Because of the rheological properties the adhesive must be fi nely tuned for the application, combining a carefully chosen polymer architecture and monomer composition with the proper addition of small additives called photoinitiators. The best way is using the unsaturated copolymerizable photoinitiators and their direct incorporation into polymer chain during the polymerization process. Progress in the coating technology and the development of novel photoreactive acrylic adhesives will open the door to new applications and an extended market penetration of UV-crosslinkable acrylic adhesive raw materials containing unsaturated copolymerizable photoinitiators incorporated into the polymer backbone. Photoreactive UV-crosslinkable acrylic PSA are characterized by good tack, good adhesion, excellent cohesion and very low shrinkage.