专利名称：PROCESS FOR PREPARING A UREA-FORMALDEHYDE RESIN HAVING A VERYLOW MOLE RATIO OF FORMALDEHYDE TOUREA
发明人：Ho C. Kong申请号：US06/675195申请日：19841127公开号：US04603191A公开日：19860729
摘要：Urea and formaldehyde are mixed in a mole ratio of about 1:2. The mixture iscondensed for 30 minutes at a pH of 7.0 to 7.4 and a temperature between 80° and 85° C.The condensation is continued at a pH of 4.8 to 5.8 at the same temperature until theviscosity reaches values between 15 and 50 mPa.s. The mole ratio of urea to
formaldehyde is adjusted to a value of 1:1.80 to 1:1.90 by adding urea. The condensationis continued under acidic conditions at the same temperature, until the viscosity reachesvalues of 35 to 80 mPa.s. At a pH of 5.8 to 6.5, the mole ratio of urea to formaldehyde isadjusted to a value between 1.0:1.0 and 1.0:1.30 by adding urea. The temperature isallowed to drop freely. When the temperature has dropped to below 50. degree. C., thepH is adjusted to a value of 7.0 to 8.0.
申请人：ENIGMA N.V.
代理机构：Ladas & Parry
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