Main Characteristics Of Polyether Polyols

Polyether polyols [2] are oligomers with ether bonds (- R-O-R -) in the main chain and more than 2 hydroxyl groups (- OH) in the end or side groups. [3] It is formed by ring opening polymerization of low molecular weight polyols, polyamines, or compounds containing active hydrogen with oxidized olefins under the action of a catalyst. Oxidized olefins mainly consist of propylene oxide (propylene oxide) and ethylene oxide (ethylene oxide), with propylene oxide being the most important. The starting agents for polyols include binary alcohols such as propylene glycol and ethylene glycol, ternary alcohols such as glycerol trimethylolpropane, and polyols such as pentaerythrine, tetranol, xylitol, sorbitol, and sucrose; The amine initiators are diethylamine, diethylenetriamine, etc.
Polyethers generally use propylene glycol polyethers with molecular weights of 800-2000, trimethylolpropane polyethers with molecular weights of 400-4000, and hydroxyl terminated polytetrahydrofuran. Polyether resins used as adhesives should remove residual alkaline catalysts during polymerization, as they can catalyze the dimerization of isocyanates and affect the quality of the adhesive. Acids are usually used to neutralize polyethers, making them weakly acidic (without affecting the reaction of polyurethane). Polyether used to prepare polyurethane adhesive has strict requirements. In addition to hydroxyl value and acid value, the content of potassium and sodium ions should be less than 10, and the water content should be less than 0.05%, otherwise gel may be generated. The polyurethane adhesive prepared with polyether resin has good water resistance, impact resistance, and low temperature resistance.
Polyether polyols with different functionalities can be prepared based on the number of active atoms contained in the initiator. The most commonly used polyethers in the preparation of polyurethane adhesives are polyoxypropylene glycol and polyoxypropylene triol, as well as polytetrahydrofuran glycol.