| 摘要 |
The invention provides a process for the production of an unsaturated polyester resin comprising in a first step (1) providing and allowing to react (i) dihydric alcohol or oxide and (ii) dibasic carboxylic acid or anhydride, in a second step (2) adding an unsaturated carboxylic acid or anhydride and optionally further dihydric alcohol or oxide to the reaction mixture and further reacting the reagents, wherein the dihydric alcohol or oxide comprises an ethylene glycol oligomer having from 1 to 4 ethylene oxide units or an oxide of such an oligomer and adding to the resin mixture a fire retardant material which is a solid ammonium polyphosphate or derivative thereof. The product shows improved fire retardancy and can be used in applications such as public transport where this is desired. |
