| 摘要 |
PURPOSE:To produce a polyurethane which can give a film excellent in hardness, chemical resistance, weather resistance, water resistance and alkali resistance, by reacting an organic polyisocyanate with a specified polyalcohol. CONSTITUTION:Glyoxalic acid is reacted with a corresponding phenol in the presence of a mineral acid of a strongly acidic ion exchange resin, and the product is esterified, if desired, to obtain a bis(4-hydroxyphenyl)acetic acid of the formula (wherein R1 is H, an alkyl, an alkali metal or ammonium ion, and R2-3 are each H or an organic residue). 1mol of the hydroxyl groups of a polyhydric alcohol comprising 5-100mol% said bis(4-hydroxyphenyl)acetic acid and 95-0mol% at least dihydric low-MW polyol or polyether polyol are reacted with an at most equimolar amount of an organic polyisocyanate (e.g., 2,4-tolylene diisocyanate) at 40-80 deg.C.
|
