Solid-State Condensation Polymerization of Aromatic Oligoesters from Bisphenol A and Diphenyl Terephthalate/Isophthalate Mixtures

Takashi IWAMOTO, Takashi KINOSHITA and Junzo MASAMOTO*

Department of Polymer Science and Engineering, Kyoto Institute of Technology;
Matsugasaki, Sakyo-ku, Kyoto-shi 606-8585 Japan
Chemicals and Plastics Development Laboratory, Asahi Chemical Industry Co., Ltd.;
3-13, Ushiodori, Kurashiki-shi 712-8633 Japan

Industrially available aromatic polyesters of bisphenol A polyarylate is conventionally produced by the interfacial condensation polymerization of bisphenol A and the mixture of terephthaloyl/isophthaloyl chlorides. We now report a new synthetic method without using the acid chloride derivatives. The synthesis of oligomeric polyarylate by the melt condensation polymerization of bisphenol A and diphenyl terephthalate/isophthalate(mole ratio of reactants is 1/0.5/0.5), and the crystallization of this oligomeric polyarylate contacting with the proper solvent have been previously repoted. This crystallized oligomeric polyarylate could be polymerized by the solid-state condensation polymerization into a high molecular weight polymer with excellent color. The key point to obtain a high molecular weight polymer was to adjust precisely the mole ratio of the end-groups of -OH and phenyl. The molecular weight of the obtained polymer reached to twice that of the commercial polyarylate and the molecular weight distribution had the most probable distribution of Mw/Mn=2. The high molecular weight polyarylate showed an excellent wear property. The melting points of the obtained polymers were over 280 °C, and some polymers showed a melting point over 300 °C. These values were nearly 40 °C higher than the reported value of the maximum melting point of the random copolyarylate composed of bisphenol A, terephthalic and isophthalic acid(mole ratio of bisphenol A/terephthalic/isophthalic acid=1/0.5/0.5).

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