| 摘要 |
A spray condensation method for the production of dried resins (I) in powdered form from urea and/or melamine and aldehyde(s) by drop formation, in which the reaction mixture of the above components is formed in situ in the spray reactor and shows a pH of less than 1. Independent claims are included for (1) resin particles with a wall thickness of 0.1-5 microns obtained by this method (2) expanded resin particles obtained by this method, with a particle diameter of 30-500 microns and with a ratio of closed-pore surface to open-pore surface equal to (1:1)-(1:0) .
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