Shozaburo Imai

Curable copolymers of isobutylene and acrylic ester

Abstract Curable copolymers of isobutylene and acrylic ester were successfully synthesized by incorporation of a third monomer into alternating copolymers of isobutylene and acrylic ester by means of complexed copolymerization catalysed with alkylboron halide. As the third monomer, acrylic ester including an unsaturated bond in the ester group (AEU), such as crotyl acrylate, or vinyl monomer including a chlorine atom (CVM), such as 2-chloroethyl vinyl ether, was effectively incorporated. The terpolymers containing AEU (AIDM) were easily vulcanized with sulfur. The terpolymers containing CVM (AICM) were sufficiently well cured with polyamine. The cured products of both AIDM and AICM had excellent properties in terms of oil resistance, water resistance and others. The blend of AIDM and ethylenepropylenediene rubber was satisfactorily co-vulcanized with sulfur.

Characteristics Of The Mass-Produced Optical Disks

Sumitomos mass production plant for write once optical memory disks has been operational since the summer of 1985. The product disk, which has the sandwich structure with an air gap and which has the sensitive layer based on tellurium, exhibits equal or better read / write characteristics and reliability compared with ones from the laboratory. It will be demonstrated that the disks are particularly suited for high speed and high density data recording at an adequetly low error rate and also that the result of accellerated aging tests assures an excellent archivability.

Molding Compounds For Optical Disk Substrates

Birefringence is generally caused by the orientation of the optical anisotropic molecular chain introduced during the injection molding of plastic substrates. It was found that the degree of birefringence of molded disk depends on the value of the difference between the polarizabilities parallel and perpendicular to the molecular chain. This difference in polarizabilities is proportional to the optical elastic constant of the polymer in the elastic state. It was determined that the negative and positive segmental polarizabilities may be fully compensated by mixing two polymers with opposite molecular optical anisotropy in an optimal ratio. Using this method an injection molded substrate was developed which demonstrated minimal birefringence.