Views: 2 Author: Site Editor Publish Time: 2023-07-04 Origin: Site
Polyether polyol is a zwitterionic compound containing an ether bond (ROR) and an OH group at the end of the molecule. It is made of low molecular compounds containing active hydrogen such as (alcohols, amines) as a starting agent, and under the action of catalysts, it is polymerized with ethylene oxide (EO), propylene oxide (PO), epoxy butane (BO) and other ring-opening reactions. The largest production of polyether polyol is to use glycerol (propylene glycol) as the starting agent and epoxide (generally PO and EO are used), and various general polyether polyol can be produced by changing the conditions of PO and EO dosing method (mixed dosing or separate dosing), dosing ratio and dosing order.
Polyether polyol is an important chemical raw material, its biggest use is the synthesis of polyurethane (PU) resin products, such as polyurethane foam, polyurethane adhesives, polyurethane elastomers, etc. In addition, it can also be used as a nonionic surfactant, lubricant, liquid fluid, heat exchange fluid, etc. The early synthesis of polyether polyol polymerization reaction is carried out under the action of acid or alkali catalyst, the commonly used acid catalysts are protonic acid (H2SO4, HCl, etc.) and Lewis acid (AlCl3, BF3, etc.), alkali catalysts are commonly used alkali metal, alkali (earth) metal oxides, alcoholic compounds and hydroxides.
For polyether polyol produced by oxidized propylene ether diol, the specific industrialization is basically divided into three steps, such as raw material pretreatment, polymerization reaction and post-treatment, and the process is briefly described as follows:
First, the raw material pretreatment: in the ring-opening poly make reaction, in order to ensure the reaction speed of polyether polyol synthesis, molecular weight control and product color, unsaturation, etc., the first to purify the polymerization monomer, in addition to removing the catalyst, starting agent with the reaction system with water, aldehyde, oxygen, polyhydroxy sugars and other trace impurities.
Second, ring-opening polymerization reaction: ring-opening polymerization reaction with epoxide as raw material is an exothermic reaction, so the reaction process with condensate in time to remove the heat of reaction. In addition, oxygen will produce oxidation and blocking effect on the polymerization reaction, so the reaction must be pumped out the air in the reaction kettle as much as possible before the reaction to ensure that the reaction is carried out in the absence of oxygen, and at the same time, in the process of the reaction, vacuum should also be constantly pumped so as to be able to produce high quality polyether polyol.
Third, the post-treatment process: the crude polyether polyol products generated by the completion of the polymerization reaction must undergo post-treatment. Post-treatment work mainly includes neutralization, adsorption, dehydration, filtration, distillation and other units. After a series of post-treatment, polyether polyol not only neutralizes and filters out the catalyst impurities remaining in it, but also uses adsorption, dehydration and distillation processes to remove other harmful impurities in order to obtain polyether products with low water content, light color, no odor, good performance and homogeneity.
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