| 摘要 |
To obtain a UF foam which is low in formaldehyde, yet is dimensionally stable, up to 96% urea is dissolved in an approximately 10 to 30% aqueous extract of an alkyl, aryl or alkaryl sulphonic acid, said solution being mixed with a conventional hardener/foaming agent solution containing the sodium salt of an alkyl, aryl or alkaryl sulphonic acid in an aqueous diluent usually employed for foaming, in a ratio sulphonic acid solution to sodium sulphonate solution of 1:1 to 1:4, the pH value being adjusted to 0 up to 3 and said mixture being foamed together with a urea formaldehyde resin precondensate solution in the usual manner. |
