Process for preparing hydroxy-functionalized polybutadiene

A process for preparing hydroxy-functionalized polydiene comprising reacting monomer diene with hydrogen peroxide in the presence of a hydrophilic organic solvent, wherein the total amount of monomer diene used is added to a reaction in at least two parts, wherein a second part of the monomer diene is added to the reaction at a temperature of a reaction mixture that is at least +5 K different from the temperature of the reaction mixture at an addition of a first part of the monomer diene,

• wherein the process further comprises the steps:
• a) heating hydrophilic organic solvent to a temperature of from 75 to 105° C.,
• b) adding the first part of the total amount of monomer diene before, during, or after step a) resulting in a pressure of from 0.1 to 5.0 MPa,
• c) adding the hydrogen peroxide to the mixture,
• d) heating the mixture obtained in step c) to a temperature of from 110 to 150° C.,
• e) adding the second part of the total amount of the monomer diene in step d) while heating or at the final temperature obtained in step d), and keeping the reaction mixture at a temperature equal to or maximal differing +/−10 K from the temperature obtained in step d),
• f) terminating the reaction.