Abstract: A copolymerized polyamide, comprising amide bonds formed by an aliphatic diamine with 4 to 14 carbon atoms and terephthalic acid, with the existence ratios of distributed respectively adjacent amide bonds satisfying the following formulae (A) and (B), and with the half-crystallization time satisfying the following formula (C).0.9.ltoreq.[XY]obs./[XY]calcd.<1.1 (A)0.9.ltoreq.[XX]obs./[XX]calcd.<1.1 (B)wherein X stands for an amide bond formed by an aliphatic diamine with 4 to 14 carbon atoms and terephthalic acid, and Y stands for any other amide bond than X. [XY] refers to the rate at which X and Y are adjacent to each other among all the amide bonds in the polymer structure, and [XX] refers to the rate at which X and X are adjacent to each other among all the amide bonds in the polymer structure. [XY] calcd. and [XX] calcd. are respectively the values of [XY] and [XX] calculated on the assumption that X and Y amide bonds are distributed statistically at random, and [XY] obs. and [XX] obs.

Abstract: Disclosed is an optical recording material comprising a porphine derivative having at least an ionic group and a polymer compatible with this porphine derivative. As the porphine derivative, there are used a porphine derivative having an N-alkylpyridinium group, such as 5,10,5,20-tetra(4-N-methylpyridinium) porphine, a porphine derivative having a quaternary amino group, such as 5,10,15,20-tetra(4-N,N,N-trimethylaminophenyl) porphine, a porphine derivative having a sulfonatophenyl group, such as 5,10,15,20-tetra (4-sulfonatophenyl) porphine, and a porphine derivative having a carbonatophenyl group, such as 5,10,15,20-tetra-(4-carbonatophenyl) porphine. Either an organic polymer or an inorganic polymer is used as the polymer. From the viewpoint of the recording stability, a water-soluble polymer such as polyvinyl alcohol or sodium polystyrene sulfonate is preferred as the organic polymer.