Method for preparing a resol-type phenolic resin with reduced formaldehyde content

A method for preparing a resol-type phenolic resin comprising the following steps:

• a) a step of condensing phenol and formaldehyde, in a basic medium, the formaldehyde being in molar excess with respect to the phenol, at a condensation temperature of at least 50° C. until the phenol conversion rate is 50 to 80%, whereby a resol-type phenolic resin results comprising free formaldehyde;
• b) a step of measuring the free formaldehyde mass content of the phenolic resin obtained in a);
• c) a step of reducing the free formaldehyde mass content of the phenolic resin obtained in a) by placing it in contact with a material consisting of an aminophenolic compound and either ethanol or an ethanol and water mixture, the aminophenolic compound being in an excess amount with respect to the free formaldehyde and at a temperature lower than the condensation temperature of step a).