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PROCESS FOR MULTILAYER SYSTEM ELEMENTS PREPARATION ON THE PROCESS FOR MAKING CARBAMIDE-FORMALDEHYDE RESIN WITH VERY BASIS OF HARD POLYURETHANE FOAM LOW FORMALDEHYDE TO CARBAMIDE CONTENT
PROCESS FOR MULTILAYER SYSTEM ELEMENTS PREPARATION ON THE PROCESS FOR MAKING CARBAMIDE-FORMALDEHYDE RESIN WITH VERY BASIS OF HARD POLYURETHANE FOAM LOW FORMALDEHYDE TO CARBAMIDE CONTENT
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机译:硬质聚氨酯泡沫低甲醛含量高的制备氨基甲酸酯-甲醛树脂的过程的多层系统元件的制备方法
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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 DEG 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.
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