| 摘要 |
<p>A method of preparing a modified phenol-formaldehyde resin in solid particulate form comprising reacting together, in an aqueous medium, phenol and formaldehyde, in a ratio of 1.0 mole phenol to between 1.8 and 3.5 moles of formaldehyde, in the presence of between 0.1 and 1.0 moles of a basic catalyst; continuing this reaction until a desired viscosity is reached; modifying the reaction system by adding thereto between 0% and 30%, based on the weight of phenol originally taken of a non-phenolic polyhydroxy compound; spray drying the thus modified liquid resin in a pressure nozzle drier, and chilling the spray dried particulate solid. These solid resins are redispersible in water and stable on storage, compared to the known aqueous, equivalent, systems.</p> |
