| 摘要 |
<p>A method of producing urea-modified, highly reactive phenolic resins useful as bonding agents for center-layer particles in the manufacture of particleboard, comprising condensing phenol and formaldehyde under alkaline conditions, adding 30 to 50 wt.% of urea, based on the phenol-formaldehyde condensation product, obtaining urea-modified phenolic resins which contain 50 to 70 % solids, 2 to 8 wt.% of alkali (calculated as NaOH) and adding a sufficient amount of an alkaline solution to said urea-modified phenolic resins in order to ensure a total alkali content of 7 to 13 wt.% (calculated as NaOH) in the resins.</p> |
