Network Formation of Polyether-diisocyanate with Anionic Catalystt

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  • SASAKI Nobuyoshi
    Department of Industrial Chemistry, Faculty of Engineering, Kinki University
  • MORI Tetsuo
    Department of Applied Chemistry, Faculty of Engineering, Kyushu University
  • YAMAGUCHI Yukio
    Texas Technical University
  • YOKOYAMA Tetsuo
    Department of Material Engineering, Faculty of Engineering, Nagasaki University
  • TANAKA Takehide
    Department of Applied Chemistry, Faculty of Engineering, Kyushu University

Bibliographic Information

Other Title
  • アニオン触媒によるポリエーテルジイソシアナートの三次元化

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Description

It was found that urethane prepolymers, that is, diisocyanate adducts of polyether glycol, in DMF solution were rapidly crosslinked by the catalytic action of sodium cyanide. By evapolating to dryness, three-dimensional polymers were obtained. Anionic catalysts such as nbutyl lithium, sodium benzophenone ketyl and sodium benzoate were also found to be effective for the crosslinking of prepolymers. The crosslinking reactions of prepolymers with sodium cyanide in DMA solution were studid by determining the gel point. Gelation time decreased with increasing catalyst concentration and prepolymer concentration. The apparent activation energy of gelation was ca.18 kcal for polypropylene glycol-tolylene diisocyanate at 0∼25°C and ca.35 kcal for polypropylene glycol-hexametylene diisocyanate at 55∼80°C. The crosslinking reaction of prepolymers, prepared from polypropylene glycol and tolylene diisocyanate, in DMA solution with sodium cyanide catalyst was followed at 25°C by the titration of unreacted isocyanate groups, and was found to obey apparent third-order. The infrared spectrum of the resulting polymer shows an absorption at 1410 cm-1 corresponding to isocyanurate ring. From these results, it was considered that the crosslinking is effected by trimerization of isocyanate groups. The resulting network polymers were rubbery at room temperature and gel fractions of these polymers were mostly near 1. Densities, swelling properties, glass transition temperature, Young's modulus, tensile strengths and elongations were also measured. Polyurethanes prepared from hexametylene diiscyanate have good mechanical properties (tensile strength 130∼320 kg/cm2 and elongation 450∼1000%). DTA and TGA measurement showed these polymers were stable up to 280∼320°C.

Journal

  • NIPPON KAGAKU KAISHI

    NIPPON KAGAKU KAISHI 1972 (2), 413-422, 1972-02-10

    The Chemical Society of Japan

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