Title: Process for preparing vrea-formaldehyde resin having very low mole ratio of formaldehyde to urea
Application Number: 85104298 Application Date: 1985.06.04
Publication Number: 1006950 Publication Date: 1987.01.14
Approval Pub. Date: Granted Pub. Date: 1990.08.01
International Classifi-cation: C08G12/12
Applicant(s) Name: Enigma N.V. Address:
Inventor(s) Name:
Attorney & Agent: HUANG JIAWEI
Abstract:
     Urea and formaldehyde are mixed in a mole ratio of about 1:2. The mixture is condensed for 30 minutes at a pH of 7.0 to 7.4 and a temperature between 80 and 85 deg.C. The condensation is continued at a pH of 4.8 to 5.8 at the same temperature until the viscosity 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 condensation is continued under acidic conditions at the same temperature, until the viscosity reaches values of 35 to 80 mPa.s. At a pH of 5.8 to 6.5, the mole ratio of urea to formaldehyde is adjusted to a value between 1.0:1.0 and 1.0:1.30 by adding urea. The temperature is allowed to drop freely. When the temperature has dropped to below 50 deg.C, the pH is adjusted to a value of 7.0 to 8.0.
Time: 4
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