Method for preparing polyether polyol in recycling manner by aid of DMC (double metal cyanide) catalyst

Abstract

The invention discloses a method for preparing polyether polyol in a recycling manner by the aid of a DMC (double metal cyanide) catalyst. The method includes carrying out polymerization reaction on first low-molecule alcohol and alkylene oxide to obtain polymers with low molecular weights; carrying out reaction on the polymers with the low molecular weights, DMC, acid and alkylene oxide, simultaneously filling the polymers with the low molecular weights with a certain quantity of second low-molecule alcohol used as a raw material to obtain intermediate target polymers; preparing target polymers from a part of the obtained intermediate target polymers and preparing other intermediate target polymers from another part of the obtained intermediate target polymers in a recycling manner. The first low-molecule alcohol is used as a raw material. The polymers with the low molecular weights are used as initiators, the DMC is used as the catalyst, and the acid is used as an auxiliary. The average molecular weight of the intermediate target polymers is identical to the average molecular weight of the polymers with the low molecular weights. The method has the advantages that the polyether polyol can be prepared by the aid of the method in the recycling manner without alkali manufacturing initiators, and accordingly loss of materials and discharge of filter residues and wastewater can be reduced; the DMC catalyst in reaction systems for initial reaction is already activated under the condition that the concentration of the DMC in the target polymers keeps identical, accordingly, the dehydration time and the initiation time can be shortened to a great extent in production procedures, and the utilization efficiency of devices can be improved.

Description

technical field [0001] The invention relates to the field of production methods of polyether polyols, in particular to a method for preparing intermediate target polyether polyols by using a DMC catalyst and using the intermediate target polyether polyols to prepare target polyether polyols. Background technique [0002] At present, polyether polyols made of DMC catalysts are generally low-molecular alcohols as raw materials at home and abroad, such as propylene glycol (dihydric alcohol) or glycerin (trihydric alcohol), etc., under the catalysis of common bases such as potassium hydroxide, propylene oxide or The mixture of propylene oxide and ethylene oxide is made into a dihydroxyl molecular weight of about 400 and a trihydroxyl group of about 600. After being neutralized by phosphoric acid, the complicated process of dehydration and filtration after adsorption by the adsorbent, the intermediate polyether will lose about 2%. , which also brings troubles to environmental pro...

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Problems solved by technology

[0005] Patent CN03155029.0 discloses an active starting mixture and related methods. The molecular weight of the target polymer produced by this method is relatively low, and this method cannot be applied to the production process of long-chain polyether. At the same time, the embodiment of this method Among them, the raw material low molecular alcohol is not added continuously, which will lead to high concentration of raw material low molecular alcohol in the reaction system, and then lead to too long induction time and reaction time

[0006] Patent CN200710138709.8 discloses a production method of polyether resistant to high water content. The main purpose of this method is to produce a polyether resistant to high water content. After the reaction itself, the influence of water content in the starting material, this method In order to directly produce the target polymer, the output is relatively low. In the process of continuous production, the induction time of the reaction itself is relatively long, and in the process of producing polyether in its embodiment, propylene glycol and propylene oxide are added simultaneously. and cut off at the same time, this will lead to a wider molecular weight distribution (weight-average molecular weight / number-average molecular weight) of the target product produced, which will affect the performance of the target product itself

[0007] Patent CN201010217182.X discloses a short-chain polyether polyol prepared by DMC catalysis from an ultra-low water content starter. The product produced by this method is a short-chain polyether polyol. The starter itself contains Moisture content is lower than 500ppm, the raw material alcohol of low molecular weight, application scope is small, and this method can not be used for producing the polyether polyol of long chain, and the polyether polyol of short chain that itself produces in reaction process needs to carry out post-processing simultaneously. Processing, greatly increased the solid waste amount and liquid waste amount of reaction, improved production cost; Its glycerin and propylene oxide are continuous and feed simultaneously in the embodiment of reaction, can cause product molecular weight distribution wide like this

[0008] Patent CN201280015084.5 discloses a method for producing short-chain polyfunctional polyether polyols using superacids and double metal cyanide catalysts. The target product produced by this method is polyether polyols with tempered terminal functional groups, and its starting compound is 3 1 to 9 low-molecular-weight compounds of hydroxyl groups are difficult to directly apply to unit alcohols and dibasic alcohols. Meanwhile, in its embodiment, in the production process of the target polymer, propylene oxide and low-molecular raw material alcohols such as glycerin are simultaneously carried out. Feed time will cause the reaction rate to slow down and eventually terminate the reaction prematurely

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