A method for the continuous production of polycarbonate-polyether polyols in a pipeline by a preheating liquid phase method

Abstract

The invention discloses a method for the continuous production of polycarbonate-polyether polyols in a pipeline by a preheating liquid phase method, which comprises the following steps: (1) feeding raw materials including epoxy compounds, catalysts and chain transfer agents into the After mixing evenly in the premixing tank, pump it into the pipeline reactor; (2) preheat the carbon dioxide to 50-120°C, pump it in from the inlet of the pipeline reactor, and pressurize it to 1-15MPa; (3) Heating to 70-150°C, so that in the presence of a catalyst, chain transfer agent, epoxy compound and carbon dioxide are contacted in a pipeline reactor to carry out polymerization reaction; (4) part or all of the polymerization reaction product stream of step (3) flows Through the cooling section group, part of the polycarbonate-polyether polyol is separated, and the remaining polymerization product stream is recycled to step (1); wherein, the catalyst is modified by mixed acid, and the water-soluble metal salt of zinc and cobalt is added to the It can be obtained by reaction in water-soluble solvent.

Description

technical field [0001] The invention relates to a pipelined and continuous production method of polycarbonate-polyether polyol by a preheating liquid phase method. Background technique [0002] Polycarbonate-polyether polyol is a kind of polyol with carbonate group in the molecule and hydroxyl group at the end of the molecular chain. carbon dioxide (CO 2 ) and epoxy compound regulation copolymerization method is CO 2 A chain transfer agent is added during the copolymerization with epoxide, and the molecular weight of the product is controlled by controlling the chain transfer of the reaction. Studies have shown that 20wt% CO 2 CO 2 Compared with the preparation process of traditional polyether polyols, the preparation process of polycarbonate-polyether polyols can reduce 11-19% of greenhouse gas emissions and 13-16% of energy consumption. Therefore, CO 2 The method of regulating copolymerization with epoxy oxide has broad application prospects and high industrial value....

AI Technical Summary

Problems solved by technology

[0004] First of all, in terms of carbonate unit content in polycarbonate-polyether polyols; it has been known for a long time to prepare copolymers from epoxides (such as propylene oxide) and carbon dioxide. In terms of catalysts, the prior art generally uses zinc cobalt Copolymerization reaction of carbon dioxide and propylene oxide of double metal cyanide complex catalyst (zinc-cobalt DMC catalyst), specifically, the catalyst and the entire amount of propylene oxide are introduced into the reactor and carbon dioxide is added before the heating reaction; at present The problem that exists is, in industry, when adding catalyst and the epoxy monomer mass ratio that adds will be ≤ 1 / 1000 (that is catalyst charging amount ≤ 1000ppm, i.e. 0.1wt%), overall production cost and catalyst residual cost It is relatively low and has economic value

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 will be broadened, and the proportion of by-product cyclic carbonate will increase, which will reduce the quality of the product

[0010] 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

The large and uncertain amplification effect will bring many disadvantages to the industrial application of the process. For example, when scaling up to industrialization, only multiple step-by-step amplification methods can be adopted, and in order to obtain results consistent with the laboratory scale, It is necessary to re-adjust and optimize the process conditions and parameters every time the amplification process is carried out, which will greatly consume manpower and material resources and project development time; Achieve good results on a laboratory scale; at the same time, the large and uncertain amplification effect will affect the stability and reliability of the process, resulting in unstable product quality and difficult to control; in addition, this will also bring potential safety risks to the production process

Another disadvantage of the semi-batch or batch process is that the process has to be stopped in order to remove the product, thus resulting in a loss of time

[0020] Compared with other conventional copolymerization reactions, the particularity of the polycarbonate-polyether polyol copolymerization reaction is to increase the content of carbonate units in the polycarbonate-polyether polyol, and to optimize the polycarbonate-polyether polyol The molecular weight distribution of alcohol products has a common influencing factor. This influencing factor is due to the increase of the molecular weight of polycarbonate-polyether polyol, the viscosity increases, and the high-viscosity copolymerization reaction system hinders carbon dioxide from participating in polymerization. Carbonate units are formed in the molecules of carbonate-polyether polyols. At the same time, the heat and mass transfer efficiency of the high-viscosity copolymerization reaction system is reduced, and it is easy to generate high temperature and epoxide aggregation locally, resulting in violent polymerization of epoxides. A large number of polyether chain links are generated in the interior, resulting in tailing phenomenon, which further increases the viscosity of the copolymerization reaction system. Therefore, under the existing technical conditions, high molecular weight polycarbonate-polyether polyols are often accompanied by polycarbonate-polyether The content of carbonate units in ether polyol is low. Correspondingly, polycarbonate-polyether polyol with high content of carbonate units often means low molecular weight, or the molecular weight distribution range of polycarbonate-polyether polyol products. Wide, the polymer molecular weight polydispersity index (PDI) has a higher value, and even has obvious tailing phenomenon; the amplification effect of producing polycarbonate-polyether polyol does not exist in isolation, and it is also related to the improvement of polycarbonate - The content of carbonate units in polyether polyol is related to the molecular weight distribution of polycarbonate-polyether polyol products. As the molecular weight of polycarbonate-polyether polyol increases, the viscosity increases, and high-viscosity The heat and mass transfer efficiency of the copolymerization reaction system is reduced, and it is easy to form a dead zone in the reaction device, which makes the amplification effect larger

[0021] Therefore, improving the carbonate unit content of polycarbonate-polyether polyol, optimizing the molecular weight distribution of the product of polycarbonate-polyether polyol and solving the amplification effect of large-scale production of polycarbonate-polyether polyol When it is necessary to optimize and improve polycarbonate-polyether polyol catalyst, polycarbonate-polyether polyol copolymerization reaction process and polycarbonate-polyether polyol synthesis equipment, etc., at present, there are some Improvements in one of the above three aspects also have corresponding technical effects, but those skilled in the art urgently need a technical solution that can solve the above three problems at the same time, but there is no such technical solution in the field at present

Images