| 摘要 |
PURPOSE: To obtain a polyurethane foam having good mechanical strengths and good water absorbency with a low degree of swelling on absorption of water by using a polyol component containing a specified amount of a specified hydroxylated carboxylic acid. CONSTITUTION: This polyurethane foam is obtained by reacting a polyisocyanate with a polyol component containing at least 30wt.% hydroxylated carboxylic acid having at least one carboxyl group and at least two hydroxyl groups in the molecule. An example of preferable hydroxylated carboxylic acids in particular is one obtained by reacting an active hydrogen compound having a functionality of at least 3 with a cyclic carboxylic acid anhydride. The active hydrogen compound preferably comprises a polyester polyol with a molecular weight of about 300 to 8,000 and a functionality of at least 3. The molar ratio of the active hydrogen compound to the cyclic carboxylic acid compound is adjusted so as to provide at least 2mol of hydroxyl groups of the obtained hydroxylated carboxylic acid. The foam is obtained by mixing under agitation in the presence of a catalyst. |
