A kind of preparation method of polycarbonate-polyether diol

Abstract

The invention discloses a preparation method of polycarbonate-polyether diol, the number-average molecular weight of polycarbonate-polyether diol is 500-5000, comprising the following steps: (1) comprising epoxide, catalyst , initiator and carbon dioxide are imported into the premixing tank for premixing, and then introduced into the pipelined continuous reactor, and in the presence of the catalyst, the initiator, epoxy compound and carbon dioxide are contacted in the pipelined continuous reactor to carry out polymerization reaction; ( 2) The polymerization reaction product flow of step (1) is partly or completely flowed through the cooling section group, and part of the polycarbonate-polyether glycol is separated, and the remaining polymerization reaction product flow continues to be polymerized in a pipelined continuous reactor reaction, or cycle back to step (1); wherein, the catalyst is modified by mixed acid during synthesis, and obtained by reacting water-soluble metal salts of zinc and cobalt in a water-soluble solvent.

Description

technical field [0001] The invention relates to the field of polycarbonate-polyether diol synthesis, in particular to a preparation method of polycarbonate-polyether diol. Background technique [0002] The polycarbonate-polyether diol structure contains both polycarbonate chains and polyether chains generated by the homopolymerization of epoxy compounds, making it both high Young's modulus and flexible, making it suitable for preparing Raw material of polyurethane material. CO consumption due to the polymerization reaction to produce polycarbonate-polyether diols 2 , the transformation of greenhouse gas carbon dioxide as a raw material into polymer materials is very beneficial to environmental protection and energy reduction and emission reduction; the polymerization reaction is often accompanied by by-products of cyclocarbonate, which is a commonly used industrial product. It can be separated and purified for later sale. [0003] At present, the production of polycarbona...

AI Technical Summary

Problems solved by technology

Otherwise, the catalyst has no application value due to the increase in production cost due to the excessive addition of the catalyst

An important means of controlling the molecular weight of polycarbonate-polyether diols with a smaller molecular weight is to add a higher proportion of initiators, generally 1 / 50 to 1 / 90 of the molar number of epoxy monomers. Under such conditions , most of the catalysts will lose activity; or although a very small number of catalysts still maintain weak activity, the reaction time is greatly prolonged (more than 12 hours) to obtain the polymer, which is due to the fact that the reaction time is actually due to a higher proportion of the initiator Leads to deactivation of the catalyst, prolonging the activation process of the catalyst on the reactants (by several hours)

It takes longer reaction time and more energy consumption, which increases the production cost

In addition, under the condition of the above-mentioned higher ratio of initiator addition, the structure ratio of polycarbonate in the polycarbonate-polyether diol structure obtained by synthesis will decrease (<50%), that is, the reaction to carbon dioxide fixed rate reduction

Because the addition of a higher proportion of initiator will cause a large number of catalyst active sites to be quenched or occupied, the macroscopic manifestation is that the catalyst activity is reduced or even deactivated

The reduction of the carbon dioxide fixation rate indicates that the proportion of the low-cost carbon dioxide raw material in the polymer is reduced, which means that the proportion of the higher-cost epoxide is increased, which leads to an increase in the production cost of the polymer on the one hand, and on the other hand, is beneficial to energy saving and emission reduction. (Consumption of CO2) is also less effective

If the temperature is too high, the content of carbonate chains will be low, the molecular weight distribution coefficient PDI will become wider, and the proportion of by-product cyclocarbonate will increase, which will reduce the quality of the product

Although a small number of continuous flow processes have been developed, there are problems: there is inevitably an amplification effect, which brings many uncertainties to further industrial applications; some continuous flow processes are not fully reacted in a short period of time, and need to increase The reaction time is used to increase the conversion rate, resulting in a decrease in production efficiency

However, due to the generation of product polycarbonate-polyether glycol, the reaction system becomes viscous, which makes it difficult to separate the catalyst from the polymerization system, which has caused prior art to produce polycarbonate-polyether glycol magnification effect

[0017] Compared with general polymers, the particularity of polycarbonate-polyether diols also lies in that the inventors have found that polycarbonate-polyether diols can increase the content of polycarbonate units, optimize polycarbonate When the molecular weight distribution of ester-polyether diol and the amplification effect of producing polycarbonate-polyether diol are solved, there is mutual entanglement, there is the situation of mutual restriction, and the catalyst activity of prior art is low, especially adding higher The proportion of the initiator is generally 1 / 50 to 1 / 90 of the molar number of epoxy monomers, and the product polycarbonate-polyether diol is formed, and the reaction system becomes viscous, which makes the catalyst separated from the polymerization reaction system. It becomes difficult to reduce the mass transfer and thermal conductivity of the reaction equipment, so that increasing the content of polycarbonate units is often accompanied by a wide molecular weight distribution, and it is reflected in the presence of amplification effects during production

[0018] In summary, those skilled in the art urgently need a kind of content that can improve polycarbonate unit and optimize the molecular weight distribution of polycarbonate-polyether diol, solve the amplification effect of producing polycarbonate-polyether diol , but there is no such technical solution

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