Phase structures and optical properties of radical polymerizable adhesive compositions consisting of insoluble hydrophobic and hydrophilic componentsand a 3rd component

To produce a new kind of adhesives for optical use. several photopolymeriza ble compositions consisting of insoluble hydrophobic and hydrophilic compon ents (dimethacryloxyplroyl oligo-dimethylsiloxane (SiMA) and 2-hydroxyethyl methacrylate (HEMA)) and acry licacid tricyclo[5,2,1,0(2.6)] decane (Acryl ate) were prepared. Acrylate hits good miscibility both with SiMA and with HEMA. The optical transparency of cured compositions increased with the inc reasing ratio of Acrylate under the fixed component ratio of HEMA (15 wt%). The most transparent composition was obtained at the ratio of 70 wt% of Ac rylate. The loss of transparency in the compositions comes from a phase sep aration due to the aggregation of HEMA. The structure of the compositions c an be changed from a macroscopic phase separate structure to an optically u niform structure by the regulation of the Fraction of Acrylate. Compressive shear adhesion strength to glass remarkably increased in the range of Acry late component ratio From 30 wt% to 70 wt%. Such good adhesion strength is considered to come from good wettability caused by the existence of SIMA. T he composition including 70 wt% of Acrylate had both good transparency and high adhesion strength to glass, and bonded optical parts with thin adhesiv e layer of a few mu m thick and with very small tilt.