| 摘要 |
<p>An adhesive, esp. for bonding rubber, consists of a mainly linear polyurethane and a solvent, and additional carboxylic acid(s), esp. maleic and/or fumaric acid, added during the prepn. o the polyurethane or a pre-polymer esp. the polyester. The amt. of additional acid is 0.1-5 wt. %, w.r.t. the polyester. The adhesive has high stability and almost unlimited storage time. The bonding strength is high. Suitably the polyester may be prepd. from an acid, alcohol and glycol at 200-280 degrees C, in presence of a catalyst, to give a prod. of acid number 0.1-5 and 0.1% water content. The additional acid is added after cooling the mixt. to about 150 degrees C. The polyester is then cooled to about 70 degrees C, the isocyanate, is added and reaction is continued at 70-130 degrees C.</p> |
