The invention discloses inflaming retarding polyether
polyol, combined polyether,
polyurethane foam and a preparation method of the polyether
polyol. The preparation method of the polyether
polyol includes the steps that first, under the
inert atmosphere, diethanol amine, formalin and triethyl phosphite are mixed and reacted, reduced pressure
distillation is conducted, and an initiator is obtained; second, the initiator, the polyol,
cyanuric acid and a basic catalyst are mixed to obtain feed liquid B; or, the initiator, the polyol, the
cyanuric acid and the basic catalyst are mixed to obtain the feed liquid B; or, the initiator, the polyol, the
cyanuric acid, the basic catalyst and water are mixed to obtain the feed liquid B; third, the feed liquid B is mixed with
epoxide, after the feed liquid B and the
epoxide are reacted, feed liquid C is obtained, or
dehydration is performed after reacting, and accordingly the feed liquid C is obtained; fourth, the feed liquid C is mixed with
epoxide, and the polyether polyol can be obtained after the reaction. The polyether polyol is
halogen-free
nitrogen and
phosphorus collaboration inflaming retarding polyether polyol, the obtained
polyurethane foam has good
flame retardation, and the preparation method is easy to operate, high in yield and suitable for large-scale industrial production.