Abstract: A urethane prepolymer composition is provided comprising (a) a terminal isocyanate group-containing urethane prepolymer derived from a polytetramethylene glycol having a specific molecular weight of 700 to 1500 and an aliphatic and/or alicyclic diisocyanate and (b) a terminal isocyanate group-containing urethane prepolymer derived from a polycaprolactone diol and/or polyol having a specific molecular weight of 500 to 1500 and an aliphatic and/or alicyclic diisocyanate, the weight ratio of (a) to (b) being in the range of 80/20 to 20/80. This composition has excellent compatibility with a diol compound and/or a polyol compound, and can be formulated together with the diol compound and/or the polyol compound into a polyurethane coating composition system which forms a coating film having not only excellent weathering resistance, elastic recovery and transparency but also excellent low-temperature physical properties such as mechanical strength, flexibility and impact resistance at low temperatures, e.g., -30.

Abstract: A process for recovering heavy metal ions or heavy metal ions and halogen values from a solution comprising a lower aliphatic monocarboxylic acid, which comprises the steps of:(1) contacting a lower aliphatic carboxylic acid solution containing heavy metal ions or heavy metal ions and halogen values with an anion exchange resin, at least 60% of the ion-exchange groups of said anion exchange resin being in the bromide or chloride state, while the water concentration in the lower aliphatic monocarboxylic acid solution has been adjusted to a level lower than 20% by weight, thereby to adsorb the heavy metal ions or the heavy metal ions and the halogen values on the anion exchange resin; and(2) desorbing the adsorbed heavy metal ions or the adsorbed heavy metal ions and the adsorbed halogen values from the anion exchange resin by elution with an eluent.

Abstract: This invention relates to an improved process for recovering highly pure terephthalic acid crystals from a suspension containing terephthalic acid product obtained by the liquid phase oxidation of para-substituted aromatic compounds in the presence of oxidizing catalyst. The improvement comprises bringing said suspension into continuous countercurrent contact with ascending hot acetic acid containing water in a single tower under the conditions of specified temperature, specified ascending rate of the acetic acid containing water and specified residence time of the suspension, to replace the mother liquor of the suspension with said acetic acid, and recovering the mother liquor as an overflow, while recovering terephthalic acid as an underflow in the form of suspension of highly purified crystals and, if necessary, allowing the suspension to stay in a stirring tank.