CN111363132A

CN111363132A - Method for improving quality of polycarbonate-polyether polyol produced by liquid phase method

Info

Publication number: CN111363132A
Application number: CN202010241302.3A
Authority: CN
Inventors: 毛红兵; 王慧君; 王自修
Original assignee: Hangzhou Puli Material Technology Co ltd
Current assignee: Hefei Puli Advanced Materials Technology Co.,Ltd.
Priority date: 2020-03-30
Filing date: 2020-03-30
Publication date: 2020-07-03
Anticipated expiration: 2040-03-30
Also published as: CN111363132B

Abstract

The invention discloses a method for improving the quality of polycarbonate-polyether polyol produced by a liquid phase method, which comprises the following steps: (1) pumping raw materials into an inlet of a straight pipe type reactor, wherein the raw materials comprise a chain transfer agent, an epoxy compound, a catalyst and carbon dioxide, and the chain transfer agent, the epoxy compound and the carbon dioxide are contacted in a first heating section group to carry out polymerization reaction; (2) the reaction liquid flows to the second heating section group until the content of the polycarbonate-polyether polyol in the reaction liquid is not lower than 70 percent; (3) part or all of the polymerization reaction product flow passes through the cooling section group, part of the polycarbonate-polyether polyol is separated, and the rest of the polymerization reaction product flow is recycled to the step (1); wherein, the catalyst is a zinc-cobalt double metal cyanide complex catalyst obtained by the reaction of water-soluble metal salts of zinc and cobalt in a water-soluble solvent; the catalyst is modified by mixed acid during synthesis, and the mixed acid comprises at least one organic acid and at least one water-soluble inorganic acid.

Description

Method for improving quality of polycarbonate-polyether polyol produced by liquid phase method

Technical Field

The invention relates to a method for improving the quality of polycarbonate-polyether polyol produced by a liquid phase method.

Background

The polycarbonate-polyether polyol isThe polyol has carbonate group in the molecule and hydroxyl group at the end of the molecular chain. Carbon dioxide (CO)₂) CO regulation with epoxy compounds₂And (3) adding a chain transfer agent during the copolymerization reaction with the epoxide, and controlling the molecular weight of the product by controlling the chain transfer of the reaction. It has been proved that 20 wt% CO is contained₂CO of₂Compared with the traditional polyether polyol preparation process, the preparation process of the polycarbonate-polyether polyol can reduce 11-19 percent of greenhouse gas emission and 13-16 percent of energy consumption, so that CO₂The method for regulating and copolymerizing with epoxide has wide application prospect and high industrial value.

At present, three main aspects of the production of polycarbonate-polyether polyols need to be solved, namely, firstly, the content of carbonate units in the polycarbonate-polyether polyol is increased, and secondly, the molecular weight distribution of the product of the polycarbonate-polyether polyol is in a proper range, so that the polymer molecular weight polydispersity index (PDI) has a low value, and particularly, the tailing phenomenon of the polymerization product polycarbonate-polyether polyol needs to be reduced, and secondly, the amplification effect of the production of the polycarbonate-polyether polyol needs to be solved.

First, the preparation of copolymers from epoxides (e.g. propylene oxide) and carbon dioxide is known for a long time in terms of the carbonate unit content in the polycarbonate-polyether polyols. The preparation of copolymers from epoxides (e.g. propylene oxide) and carbon dioxide has been extensively reported. For example, copolymerization of carbon dioxide with propylene oxide using a zinc cobalt double metal cyanide complex catalyst (zinc cobalt DMC catalyst), specifically, the catalyst and the entire amount of propylene oxide are introduced into a reaction vessel before the start and carbon dioxide is added before heating the reaction.

The problem in the synthesis of polycarbonate-polyether polyols using zinc-cobalt DMC catalysts is that, in the industrial sector, the overall production costs and the costs of catalyst residues are only relatively low, so that they are of economic value, if the mass ratio of the added catalyst to the added epoxy monomer is at least equal to or less than 1/1000 (i.e.the catalyst charge is equal to or less than 1000ppm, i.e.0.1 wt%). Otherwise, the catalyst has no application value because the addition amount of the catalyst is too much, which leads to the increase of the production cost. An important control means for synthesizing the molecular weight of the polycarbonate-polyether polyol with smaller molecular weight is to add an initiator with higher proportion, generally 1/50-1/90 of the mole number of epoxy monomers, under the condition, most catalysts lose activity; or even if very few catalysts remain weakly active, the reaction times are greatly prolonged (over 12 hours) to obtain polymers, all because the reaction times are actually due to the fact that the higher proportion of initiator leads to deactivation of the catalyst, which lengthens the time for the activation process of the catalyst for the reactants (by hours). Longer reaction time and more energy consumption are consumed, and the production cost is increased.

In addition, under the condition of the addition amount of the initiator with higher proportion, the structural proportion of the polycarbonate in the structure of the synthesized polycarbonate-polyether polyol is reduced (less than 50 percent), namely the fixation rate of the polycarbonate to carbon dioxide is reduced. Since the addition of a higher proportion of initiator results in a large amount of catalyst active sites being quenched or occupied, macroscopically manifested as a reduction in catalyst activity or even deactivation. The reduction of the carbon dioxide fixation rate indicates that the specific gravity of the carbon dioxide raw material with low cost in the polymer is reduced, and indicates that the specific gravity of the epoxide with higher cost is increased, so that the production cost of the polymer is increased, and the effect of energy conservation and emission reduction (carbon dioxide consumption) is reduced. The reaction for polymerizing polycarbonate-polyether polyols is particularly characterized by the need to overcome the homopolymerization between epoxy compounds and to increase the content of carbonate units.

Chinese patent CN103403060A discloses a process for synthesizing polycarbonate-polyether polyol under DMC catalysis, the reactor of the process is different from a common stirred tank reactor in the market, a tubular reactor is adopted, and a cooling jacket is arranged outside the tubular reactor, so that the temperature control purpose can be realized; the interior of which is formed by a continuous tube section or at least two tube sections joined together, which are micro-structured, which form a continuous flow path from one side of the plate to the opposite side thereof. The front 20-60% of the internal pipe diameter length is 1.1mm to<100mm, the last 80-40% is 100 mm-500 mm, the length L and diameter d of the tube_RThe ratio of L/d_R>50. The reactor is preferably mixed with a plurality of static mixers or static mixersThe combination of the synthesizer and the heat exchanger (cooling coil). The scheme has high PO conversion rate of raw materials and is general>99 percent, the obtained product has low polydispersity index of about 1.22, weight average molecular weight of about 2100-2300 g/mol and low proportion of cyclic carbonate product, but the chain length of carbonate in the polyol produced by the technical proposal is low, and the mass (weight) of carbon dioxide embedded in the polyol produced by the technical proposal is low and is not more than 23 percent. Is not beneficial to the subsequent production of the polycarbonate-polyether polyol polyurethane. The reason is that on one hand, the catalyst has poor effect of catalyzing carbon dioxide to participate in copolymerization, and polyether chain links are generated. On the other hand, even if the activation energy for forming the polymer is lower than that for forming the cyclic carbonate, the reaction temperature is about 100 ℃ even in a tubular reactor provided with a cooling jacket on the outside, and sufficient activation energy can be given for forming the cyclic carbonate.

Secondly, the molecular weight distribution of the product of the polycarbonate-polyether polyol is optimized to be within a proper range, the polydispersity index (PDI) of the polymer molecular weight has a lower value (the minimum value of the theoretical value of the molecular weight distribution of the polymer is 1, namely, the fact that all polymer molecular chains have the same molecular weight is indicated, namely, the fact that the uniformity of the polymer reaches a perfect state, the closer the PDI of the polymer is to 1, the more uniform the molecular weight distribution of the polymer is, the better the performance is), especially, the tailing phenomenon of the polycarbonate-polyether polyol of the polymerization product needs to be reduced (the phenomenon is represented as that the PDI value is larger, generally is close to 2 or more than or equal to 2), the molecular weight distribution of the polymer is wider and is not. The tailing phenomenon refers to a phenomenon that a GPC curve of a polymer is relatively wide when the molecular weight is measured by GPC, and is particularly wide at the tail of the curve. In the copolymerization reaction of polycarbonate-polyether polyol, because reaction equipment in the prior art has insufficient heat transfer and mass transfer capacities, high temperature is easily generated locally, so that epoxide is subjected to violent polymerization, a large number of polyether chain links are generated in a short time, and the phenomena of wide polymer molecular weight distribution and trailing of a molecular weight curve are reflected macroscopically. The main reason for the amplification effect of polymer synthesis is also the insufficient heat and mass transfer capacity of the reaction equipment.

In DMC catalysis systems, polyether polyols having a molecular weight of 400 to 1000 are generally used as starters, whereas with small-molecule starters, such as ethylene glycol, propylene glycol, glycerol, etc., the polymerization does not proceed normally or the induction period of the polymerization is greatly extended. From the viewpoint of reaction energy, the activation energy for forming the polymer is lower than that for forming the cyclic carbonate, and the potential energy of the cyclic carbonate is lower than that of the polymer. Therefore, the reaction to form the cyclic carbonate is a thermodynamically favorable reaction, and the reaction to form the polycarbonate is a kinetically favorable reaction. Thus, in the temperature region of the polymerization reaction, high temperatures favor the formation of cyclic carbonates, while low temperatures favor the formation of polycarbonate-polyether polyols. The low surface/volume ratio of the stirred tank leads to inefficient dissipation of the heat of reaction (>1000kJ/kg polymer) released by the polymerization reaction, which makes it difficult to control the reaction temperature and thus the reaction progress.

Moreover, the local temperature of the reaction system is too high due to the failure of the reaction heat to dissipate, which may lead to depolymerization of the polymer product, and may also lead to excessive heat deactivation or color deepening of the catalyst, which may ultimately affect the cleanliness of the product. Synthesis of polycarbonate-polyether polyol As a gas-liquid-solid three-phase reaction, CO dissolved in liquid phase₂The concentration and the distribution uniformity of (A) have a large influence on the polymerization reaction. With Propylene Oxide (PO) and CO₂The interpolymer lines are exemplified by the fact that in CO₂At low concentrations, the homopolymerization of PO to polyether is stronger than the reaction of PO with CO₂The copolymerization into polycarbonate has high macroscopic polymerization reaction rate and small chain transfer reaction rate change, so that the obtained polycarbonate-polyether polyol has high molecular weight and low content of carbonate units. In contrast, in CO₂High concentration, slow copolymerization reaction rate, low molecular weight of the obtained polycarbonate-polyether polyol and high content of carbonate unit, so that CO in the system₂The unevenness of the distribution can also lead to a broad molecular weight distribution. In the middle and later period of copolymerization, with the continuous increase of the molecular weight of the polycarbonate-polyether polyol, the viscosity of a copolymerization reaction system is increased, and CO is limited₂Diffusion in the copolymerization system.

For example, U.S. Pat. No. 4,4500704 describes the copolymerization of carbon dioxide with propylene oxide using DMC catalysts. The process is a batch process, i.e. the catalyst and the entire amount of propylene oxide are charged before the start of the reaction and carbon dioxide is added before heating. However, this method requires introduction of the epoxide which participates in the copolymerization reaction into the autoclave in advance, and is disadvantageous in that, since a large amount of propylene oxide is introduced into the autoclave, enrichment is easily locally formed, thereby causing homopolymerization, and heat of about 1400kJ/kg of polymer is released. The large amount of reaction heat heats the copolymerization reaction system in an autoclave, making it difficult to control the copolymerization, and therefore this process has an objective insurmountable disadvantage in terms of specific operational safety.

CO in copolymerization reaction system₂The maldistribution of the distribution may also result in a broader molecular weight distribution of the polycarbonate-polyether polyol. Resulting in CO in the system₂One reason for the uneven distribution is that in the middle and later stages of the polymerization reaction, the viscosity of the system increases with the increasing molecular weight, and CO increases₂Diffusion in the system is limited. To obtain uniform molecular weight distribution and CO₂The system needs to ensure effective mass and heat transfer of the system at the later reaction stage, namely the later reaction stage with the viscosity of the system increasing continuously, and ensures CO₂The distribution uniformity in the system can be beneficial to improve the CO content of the polycarbonate-polyether polyol₂The intercalation amount and the molecular weight distribution. Therefore, one of the feasible technical solutions is that the polymerization process equipment needs to have high mass and heat transfer capacity even under the condition of high system viscosity, which is difficult to realize in practical production.

Finally, what is needed to be solved is the amplification effect of polycarbonate-polyether polyol, and most of the processes for synthesizing polycarbonate-polyether polyol at present adopt batch processes, and although a small amount of continuous flow processes are developed, the amplification effect inevitably exists due to certain differences of temperature and concentration of each point of a reaction system in a reaction device.

The Scaling up Effect (Scaling up Effect) refers to the research result obtained from the chemical process (i.e. small scale) experiment (e.g. laboratory scale) performed by small equipment, and the result obtained from the same operation condition is often very different from that obtained from the large scale production apparatus (e.g. industrial scale). The effect on these differences is called the amplification effect. The reason for this is mainly that the temperature, concentration, material residence time distribution in small-scale experimental facilities are different from those in large-scale facilities. That is, the results of the small scale experiments cannot be completely repeated on an industrial scale under the same operating conditions; to achieve the same or similar results on an industrial scale as in small scale experiments, process parameters and operating conditions need to be changed by optimal adjustment. For chemical processes, the amplification effect is a difficult and urgent problem to solve. If not solved, the production process and the product quality have great uncertainty, and firstly, the quality of downstream products is directly unstable and is difficult to control; secondly, the uncertainty can bring about the fluctuation of the technological parameters in the production process, so that the production process cannot be effectively controlled, the production safety cannot be ensured, and a plurality of potential safety hazards are buried in the production process. The amplification effect is ubiquitous, with textbook data.

The general theory of chemical process development (zhong constitutional editions, chinese petrochemical press, published 2010) gives the concept of amplification effect, and the core problem of chemical reaction process development is considered to be the solution of amplification effect. The last paragraph of 42-the first paragraph of 43 describing the so-called amplification effect refers to the difference in process results between the chemical plant or process plant after amplification and the small plant of raw materials. For example, if, after the scale-up of a chemical reactor, a reduction in the indices of reaction conversion, selectivity, yield and product quality is observed under the same operating conditions, if the cause of this reduction is not readily ascertained, this phenomenon is attributed to the scale-up effect, as compared with a pilot plant before the scale-up. As the core problem of chemical process development is amplification effect, the chemical process research is to a great extent to find the reason for generating amplification effect and a compensation method. Pages 115, the last 2 to 3 paragraphs in the foundation of chemical process engineering and process design (Zheng Dong, Wuhan university Press, 2000 published) describe that since the chemical process is often a complex interweaving of chemical and physical processes, there are many unknown problems, and therefore, not only the quantitative change but also the qualitative change is reflected in the amplification process. Before people can not know the essence of the chemical process, indexes can not be repeated by simply using the operation conditions of the original test without adopting the adjustment of acquisition measures in the amplification process. This phenomenon that the scale of the process becomes large and the index cannot be repeated until the scale of the amplification is not sufficiently known is called "amplification effect". Generally, the amplification effect is a phenomenon in which the reaction condition is deteriorated, the conversion rate is decreased, the selectivity is decreased, the yield is decreased, or the quality of the product is deteriorated after the amplification. The reason for the amplification effect is explained at page 133-135 of "typical fine chemistry optimization and amplification techniques" (edited by Zhang Showa, Zhejiang university Press, published in 2015): (1) reasons for temperature, concentration gradients; (2) the heat exchange specific surface area and the reaction period are different; (3) the dead zone is different from equipment cleaning; (4) the deviation of the temperature indication is different. The present specification reveals a great difference between laboratory devices and industrial plants. Macroscopically, the two look identical on the surface, but the two have obvious difference due to the difference of the mixed state on the microscopic level, so the amplification effect must be eliminated through the research of the amplification test. It can be seen from the above three textbooks that the amplification effect is a ubiquitous technical problem which plagues the development of the chemical process in the development of the chemical process. From the pilot scale, the pilot scale to the mass production, any process must have enough data and experience accumulation, and repeated experimental verification is carried out, rather than being completed by simply adjusting some parameters, and the process can be completed by the inventor with great creative labor. If the amplification effect is eliminated without carrying out amplification test, the performance indexes such as conversion rate, selectivity, quality and the like may be greatly reduced, which is fatal to chemical development. Therefore, the amplification effect is an unavoidable technical problem for a general chemical development process.

The processes for synthesizing polycarbonate polyether polyols are mostly batch processes. There are mainly the following problems:

1. batch operation is inefficient and reaction times are long.

2. The reaction of polycarbonate polyether polyol is exothermic and requires a reactor with good heat exchange performance to ensure that the reaction does not run away from temperature. Too high a temperature results in a low content of carbonate chain units, a broad molecular weight distribution, and a high proportion of cyclic carbonate as a by-product, which reduces the quality of the product.

Although a small number of continuous flow processes have been developed, there is a problem that amplification effects inevitably occur, which brings many uncertainties to further industrial applications; some continuous flow processes have incomplete reaction in a short time, and increase of the reaction time by delaying the pipeline is required to improve the conversion rate, which results in reduction of the production efficiency. For example, in the chinese patent CN103403060A, a tubular reactor is used at every point of the reaction system with a cooling jacket outside to achieve the purpose of temperature control, but the reaction system becomes viscous due to the formation of the product polycarbonate-polyether polyol, and therefore the invention adopts the technical means that "the first 20-60% of the length of the tubular reactor has an inner diameter of the tubular reactor of 1.1mm to <100mm, and the last 80-40% of the length thereof has an inner diameter of the tubular reactor of 100mm to 500 mm. "therefore, the inner diameters of the tubes before and after the tubular reactor are not uniform, and therefore, the heat transfer efficiency is not uniform, and the compositions of the reaction systems in the tubes before and after the tubular reactor are not uniform.

Chinese patent CN100516115C describes a method for producing polycarbonate polyol by continuous operation using a loop reactor, wherein the diameter of the outer cylinder of the loop reactor is 0.2 m, the height of the reactor is 2m, the diameter of the inner guide cylinder is 0.14 m, the height of the guide cylinder is 1.4 m, and the stirring kettle is a 10L reaction kettle. The feed flow rate was fixed at 5L/min and the proportion of carbonate chain units obtained was not higher than 37%. The main body of the process equipment is a loop reactor, the loop reactor is a cylindrical reactor, and a stirring reflux device is arranged in the loop reactor, so that the process equipment is not greatly different from a cylindrical reaction kettle in nature, and only has a little difference in the form of material flowing in a stirrer. Thus the loop reactor still has the same unavoidable amplification effect as the reaction kettle type process when scaling up to industrial scale. Namely, the scheme can not completely avoid the problem of amplification effect existing in the intermittent process, and the amplification difficulty of the process is increased. The amplification effect which is greatly uncertain brings disadvantages to the industrial application of the process, for example, when the process is amplified to the industrialization, only a method of multiple step-by-step amplification can be adopted, and in order to obtain a result which is consistent with the laboratory scale, the process conditions and parameters are readjusted and optimized in each amplification process, which greatly consumes manpower, material resources and time for project development; even if multiple progressive amplification is adopted, due to the fact that the change range of the amplification effect is too large, a good result of laboratory scale cannot be achieved after amplification can be finally achieved; meanwhile, the stability and reliability of the process can be influenced by the amplification effect which is greatly uncertain, so that the product quality is unstable and is difficult to control; in addition, this also presents a potential safety risk to the manufacturing process. Another disadvantage of semi-batch or batch processes is that the process must be stopped in order to remove the product, thus resulting in a loss of time.

The particularity of the copolymerization of polycarbonate-polyether polyols in comparison with other conventional copolymerization reactions is also the common point of increasing the carbonate unit content in the polycarbonate-polyether polyols and optimizing the molecular weight distribution of the products of the polycarbonate-polyether polyols. That is, as the molecular weight of the polycarbonate-polyether polyol increases, the viscosity increases, the high-viscosity copolymerization reaction system limits the participation of carbon dioxide in the polymerization into the molecules of the polycarbonate-polyether polyol to form carbonate units, and meanwhile, the high-viscosity copolymerization reaction system has low heat and mass transfer efficiency, so that high temperature and epoxide aggregation are easily generated locally, the epoxide is subjected to violent polymerization, a large amount of polyether chain links are generated in a short time, a tailing phenomenon is generated, and the viscosity of the copolymerization reaction system is further increased. Thus, under the conditions of the prior art, high molecular weight polycarbonate-polyether polyols tend to be accompanied by a lower content of carbonate units in the polycarbonate-polyether polyol. Correspondingly, polycarbonate-polyether polyols with high carbonate unit contents are often accompanied by low molecular weights, or the products of polycarbonate-polyether polyols have a broad molecular weight distribution range, and the polymer molecular weight polydispersity index (PDI) has a high value, or even has an obvious tailing phenomenon; the amplification effect for producing the polycarbonate-polyether polyol is not isolated, and is also associated with the increase of the carbonate unit content in the polycarbonate-polyether polyol and the improvement of the molecular weight distribution of products, the viscosity is increased along with the increase of the molecular weight of the polycarbonate-polyether polyol, the heat and mass transfer efficiency of a copolymerization reaction system with high viscosity is reduced, a dead zone is easily formed in a reaction device, and the amplification effect is increased.

Therefore, in order to improve the content of carbonate units in the polycarbonate-polyether polyol, optimize the molecular weight distribution of the product of the polycarbonate-polyether polyol, and solve the amplification effect in the mass production of the polycarbonate-polyether polyol, it is necessary to optimize and improve the polycarbonate-polyether polyol from various aspects such as the catalyst of the polycarbonate-polyether polyol, the polycarbonate-polyether polyol copolymerization process, and the polycarbonate-polyether polyol synthesis equipment, and a technical solution capable of simultaneously solving the three problems is urgently needed by those skilled in the art, but no solution is available at present.

Disclosure of Invention

The invention aims to solve the technical problem of providing a method for improving the quality of polycarbonate-polyether polyol produced by a liquid phase method. The method has the characteristics of small online reaction amount, small potential safety hazard, convenient control of reaction, continuous production and low production cost. Simultaneously solves the three technical problems of improving the content of the carbonate unit, optimizing the molecular weight distribution of the product of the polycarbonate-polyether polyol and solving the amplification effect of large-scale production.

The purpose of the invention is realized as follows:

a method for improving the quality of polycarbonate-polyether polyol produced by a liquid phase method,

the method comprises the following steps:

(1) pumping a raw material into an inlet of a straight-tube tubular reactor, wherein the straight-tube tubular reactor comprises a heating section group and a cooling section group, the heating section group is arranged at the inlet end of the straight-tube tubular reactor, the cooling section group is arranged at the outlet end of the straight-tube tubular reactor, the heating section group comprises a first heating section group and a second heating section group, the first heating section group and the second heating section group are connected in series, and the raw material comprises a chain transfer agent, an epoxy compound, a catalyst and carbon dioxide, so that the chain transfer agent, the epoxy compound and the carbon dioxide are contacted in the first heating section group in the presence of the catalyst to carry out a polymerization reaction, and a reaction liquid material flow containing the polycarbonate-polyether polyol and the cyclic carbonate is obtained;

(2) the reaction liquid stream flows to the second heating section group, the chain transfer agent, the epoxy compound and the carbon dioxide in the reaction liquid stream are contacted in the second heating section group, so as to carry out polymerization reaction, the outlet end of the second heating section group is provided with a pipeline which is connected with the inlet end of the second heating section group, so that the reaction liquid stream is circulated in the second heating section group, and the content of the polycarbonate-polyether polyol in the reaction liquid is not lower than 70 percent, so as to obtain a polymerization reaction product stream;

(3) passing part or all of the polymerization product stream through the cooling stage assembly to separate a portion of the polycarbonate-polyether polyol and to form a polycarbonate-polyether polyol product stream, and recycling the remaining polymerization product stream to step (1);

wherein, the catalyst is a zinc-cobalt double metal cyanide complex catalyst obtained by the reaction of water-soluble metal salts of zinc and cobalt in a water-soluble solvent; the catalyst is modified during synthesis by a mixed acid comprising at least one organic acid and at least one water-soluble inorganic acid, wherein: the water-soluble inorganic acid is selected from dilute sulfuric acid and dilute hydrochloric acid, and the pH value is 0-5; preferably 0 to 4; more preferably 1 to 3; more preferably 1 to 2; the dilute sulfuric acid is H₂SO₄The pH value of the aqueous solution of (1) can be obtained by adding concentrated sulfuric acid into deionized water for dilution, and is between 0 and 5; the dilute hydrochloric acid is an HCl aqueous solution, and can be diluted by adding concentrated hydrochloric acid into deionized water to obtain a pH value of 0-5.

Preferably, the outlet end of the first heating zone group is connected with the inlet end of the first heating zone group through a pipeline, so that the reaction liquid stream circulates in the first heating zone group, and the content of the cyclic carbonate in the reaction liquid stream is kept to be not higher than 30%.

Preferably, in step (3), after the polymerization reaction product stream flows through the cooling section group, the polymerization reaction product stream is pumped from an outlet of the straight tubular reactor to a gas-liquid separator, the reaction liquid stream is pre-separated into a gas phase material and a liquid phase material by the gas-liquid separator, the gas phase material includes carbon dioxide, the liquid phase material flows through a catalyst filter, after catalyst nanoparticles are separated or recovered, the liquid phase material further separates small molecule by-product cyclic carbonate by a rectification device, so that after separation, the polycarbonate-polyether polyol product stream is obtained, and then the polycarbonate-polyether polyol product stream is pumped to a polycarbonate-polyether polyol storage tank for storage.

Preferably, the rectification device comprises a falling film tower and a scraper evaporator, and the liquid phase material is subjected to a separation procedure through the falling film tower and the scraper evaporator in sequence, so as to obtain the polycarbonate-polyether polyol product stream.

Preferably, a heat exchanger is disposed between the first heating zone train and the cooling zone train such that the polymerization product stream heats the feedstock pumped in from the inlet end of the first heating zone train.

Preferably, the reaction solution flows through the first heating section group and is heated to 70-120 ℃, and then the reaction solution flows through the second heating section group and is heated to 80-130 ℃.

Preferably, the heating section group comprises a first heating section group, a second heating section group and a third heating section group, the reaction liquid sequentially flows through the first heating section group, the second heating section group and the third heating section group to perform a polymerization reaction, the reaction liquid flows through the first heating section group and is heated to 70-120 ℃, the reaction liquid flows through the second heating section group and is heated to 80-130 ℃, and the reaction liquid flows through the third heating section group and is heated to 90-150 ℃.

Further, be provided with first intermediate means between first heating section group with the second heating section group, first heating section group with can be provided with gaseous pressure feed arrangement that supplyes between the second heating section group, gaseous pressure feed arrangement that supplyes links to each other with the carbon dioxide pipeline through the pipeline for pressure keeps 2-6MPa in the straight tube tubular reactor. Further, the heating section group comprises a first heating section group, a second heating section group and a third heating section group, the first heating section group and the second heating section group are provided with a gas pressure supplementing feeding device, the second heating section group and the third heating section group can also be provided with a gas pressure supplementing feeding device, and the two gas pressure supplementing feeding devices are connected with a carbon dioxide pipeline through a pipeline, so that the medium pressure in the straight tubular reactor is kept at 2-6 MPa.

Further, the cooling zone array and the heating zone array are coupled such that the polymerization reaction product stream flows through the cooling zone array while heating the reaction fluid stream flowing into the heating zone array.

Preferably, the chain transfer agent is selected from any one or any plurality of ethylene glycol, diethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 4-cyclohexanedimethanol, neopentyl glycol, glycerol, trimethylolpropane, trimethylolethane, 1,2, 4-butanetriol, 1,2, 6-hexanetriol, pentaerythritol, dipentaerythritol, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, phthalic acid, trimesic acid, pyromellitic acid, catechol, resorcinol, and hydroquinone. The epoxide is at least one of ethylene oxide, propylene oxide, butylene oxide and epichlorohydrin.

Preferably, the catalyst is a mixed acid modified zinc-cobalt double metal cyanide complex, the concentration of the catalyst in the raw material or the reaction liquid stream is 0.01-0.5 wt%, and the molar ratio of the chain transfer agent to the epoxy compound is 1: 10-1: 200.

The invention has the following beneficial effects:

1. the method of the invention improves the carbonate unit content of the polycarbonate-polyether polyol and reduces the proportion of the by-product cyclic carbonate in the crude product by organically combining and using the novel catalyst, improving the reaction equipment and optimizing the production process. The method can continuously separate the polycarbonate-polyether polyol from a copolymerization reaction system by improving reaction equipment and optimizing a production process, thereby maintaining and strengthening the mass transfer and heat transfer capacity and effect of the reaction equipment, avoiding local overheating, and further avoiding the generation of a large amount of polyether chain links and by-product cyclic carbonate caused by the local overheating of the reaction equipment in the prior art; in the aspect of the catalyst, the activity and the selectivity of the catalyst are improved by adopting a mixed acid modification method, so that the high carbonate unit selectivity and the high activity catalytic polymerization reaction are realized under the conditions of lower temperature and higher initiator charge ratio; through the synergistic effect of the three components, the high-selectivity catalytic polymerization reaction is realized under the conditions of lower temperature and higher initiator feeding ratio, so that when the polycarbonate-polyether polyol is synthesized, carbon dioxide in a reaction system can be distributed more uniformly, polycarbonate chain links with higher proportion are contained in the product polycarbonate-polyether polyol, and the generation of polyether chain links and cyclic carbonate is also inhibited.

2. The applicant of the present invention has also surprisingly found that by improving the mass transfer and heat transfer capabilities and effects of the reaction equipment in combination with improving the selectivity and activity of the catalyst, the polycarbonate-polyether polyol product prepared by the method of the present invention has a narrow molecular weight distribution, a small polymer molecular weight polydispersity index (PDI), a value close to 1, and substantially no tailing phenomenon is observed in the molecular weight curve. The principle is that because the reaction equipment in the prior art has insufficient heat transfer capacity, high temperature is easily generated locally, so that epoxide is subjected to violent polymerization, a large number of polyether chain links are generated in a short time, and the phenomenon that the molecular weight is trailing is reflected in a macroscopic view. The catalyst, the process and the equipment used in the invention have synergistic effect, so that the high catalytic activity (the reaction time is 1 hour, the monomer conversion rate is more than 50%) is still maintained under the condition of higher chain transfer agent addition proportion (the chain transfer agent addition is 1/10-1/90 of the mole number of epoxide) or higher reaction temperature, and the prepared polycarbonate-polyether polyol has narrow molecular weight distribution and high carbon dioxide fixation rate (the mole ratio of the carbonate chain link structure on the main chain of the polymer is not less than 56.5%, namely the carbon dioxide embedding mass fraction is not less than 30%). Due to the realization of higher carbon dioxide fixation rate, two major advantages are brought to the polymer: firstly, the material cost is greatly reduced (the cost of carbon dioxide is very low compared with that of epoxide), and secondly, the main chain structure is closer to polycarbonate dihydric alcohol which is prepared by an ester exchange method and does not contain a polyether structure, so that the hydrolysis resistance, the chemical resistance, the weather resistance and other aspects are better than polycarbonate-polyether dihydric alcohol products with lower carbon dioxide fixation rate.

3. The applicant of the present invention has also surprisingly found that the process for producing polycarbonate-polyether polyols according to the present invention has no amplification effect by organically combining the use of the novel catalyst, the improvement of the reaction equipment and the optimization of the production process, the improvement of the mass and heat transfer capacity and effect of the reaction equipment, and the combination of the improvement of the selectivity and activity of the catalyst. The principle of the method is that the method continuously separates the polycarbonate-polyether polyol from the reaction system, so that the concentration of the polycarbonate-polyether polyol serving as a product in the reaction system is maintained at a low content, the viscosity of the reaction system is proper in a variation range, the variation range of the material ratio of the reaction system is also proper, the pipelines of the straight tubular reactor can have the same inner diameter from front to back, and the mass transfer and heat transfer capacities of the reaction equipment have better consistency from front to back; according to the invention, the gas pressure-supplementing feeding device is arranged between the heating sections of the straight-tube tubular reactor, so that on one hand, carbon dioxide is supplemented, on the other hand, materials in a reaction system are remixed by supplementing carbon dioxide, and the selectivity and activity of the catalyst are high, so that the local enrichment of epoxy compounds can be overcome, and the homopolymerization reaction between the epoxy compounds can be effectively avoided.

Detailed Description

The present invention is further illustrated by the following examples, which are not intended to limit the invention to these embodiments. It will be appreciated by those skilled in the art that the present invention encompasses all alternatives, modifications and equivalents as may be included within the scope of the claims.

In the present invention, the raw materials and equipment used are commercially available or commonly used in the art, unless otherwise specified. The methods in the following examples are conventional in the art unless otherwise specified.

Example 1

the method comprises the following steps:

wherein, the catalyst is a zinc-cobalt double metal cyanide complex catalyst obtained by the reaction of water-soluble metal salts of zinc and cobalt in a water-soluble solvent; the catalyst is modified by mixed acid during synthesis, and the mixed acid contains at least one organic substanceAn acid and at least one water-soluble inorganic acid, wherein: the water-soluble inorganic acid is selected from dilute sulfuric acid and dilute hydrochloric acid, and the pH value is 0-5; preferably 0 to 4; more preferably 1 to 3; more preferably 1 to 2; the dilute sulfuric acid is H₂SO₄The pH value of the aqueous solution of (1) can be obtained by adding concentrated sulfuric acid into deionized water for dilution, and is between 0 and 5; the dilute hydrochloric acid is an HCl aqueous solution, and can be diluted by adding concentrated hydrochloric acid into deionized water to obtain a pH value of 0-5.

In example 1, a zinc-cobalt double metal cyanide complex catalyst was obtained from the reaction of water-soluble metal salts of zinc and cobalt in a water-soluble solvent using a DMC catalyst; the preparation method comprises the following steps: weighing a certain mass of cobalt salt and zinc salt, specifically, sodium thiocyanatocobaltate and zinc bromide with a molar ratio of 1:4, dissolving in an aqueous solvent, and continuously stirring, wherein the aqueous solvent comprises water and tert-butyl alcohol, and the mass ratio of the total mass of the metal salt (namely cobalt salt and zinc salt) to the aqueous solvent is 1: 5. Adding inorganic acid and organic acid, wherein the inorganic acid is dilute hydrochloric acid, the pH value is 2, the organic acid is glutaric acid, the molar ratio of the inorganic acid to the organic acid is 5: 1, the molar ratio of the total mole number of the metal salt to the mole number of the acid is 4:1, stirring for several hours at the temperature of 10-100 ℃, and continuously generating precipitates. And carrying out suction filtration on the turbid liquid, and drying to obtain a filter cake. And (2) reslurrying and washing the filter cake at the temperature of 10-100 ℃ by using an aqueous solvent, specifically, washing for 3 minutes at the temperature of 100 ℃, filtering and drying after stirring for several hours to obtain the filter cake, and repeating the steps of reslurrying, washing and drying at the temperature of 10-100 ℃ for multiple times until the pH of the system liquid is 6-7, specifically, the temperature is 60 ℃ for 6 minutes each time. And further drying the solid product at 80-100 ℃ under a vacuum condition to obtain a final catalyst, and processing the catalyst into powder particles by mechanical grinding under an anhydrous drying condition before use.

In example 1, the chain transfer agent is selected from any one or any plurality of ethylene glycol, diethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 4-cyclohexanedimethanol, neopentyl glycol, glycerol, trimethylolpropane, trimethylolethane, 1,2, 4-butanetriol, 1,2, 6-hexanetriol, pentaerythritol, dipentaerythritol, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, phthalic acid, trimesic acid, pyromellitic acid, catechol, resorcinol, hydroquinone; in particular, the chain transfer agent is resorcinol.

In example 1, the epoxide is selected from at least one of ethylene oxide, propylene oxide, butylene oxide and epichlorohydrin, specifically Propylene Oxide (PO), and specifically, the raw material PO is firstly added into a straight pipe type reactor from a storage tank after passing through a purification system, and simultaneously a chain transfer agent and a catalyst are added, so that the materials conveyed into the straight pipe type reactor are uniformly mixed, and then are mixed with purified carbon dioxide, the carbon dioxide is provided by a carbon dioxide pipeline and is adjusted to be 2-6Mpa, specifically about 5Mpa, so as to obtain a reaction liquid, the reaction liquid flows through a first heating section group, is heated to 70-120 ℃, specifically about 120 ℃, and after reacting for about 0.5 hour, the reaction liquid flows through a second heating section group, is heated to 80-130 ℃, specifically about 120 ℃, an outlet end of the second heating section group is connected with an inlet end of the second heating section group through a pipeline, circulating part or all of the reaction liquid stream in the second heating section group until the content of the polycarbonate-polyether polyol in the reaction liquid is not lower than 70%, obtaining a polymerization reaction product stream after reacting for about 1.5 hours, and cooling the polymerization reaction product stream to about 60 ℃ after flowing through the cooling section group.

The polymerization product stream then flows to a gas-liquid separator; separating gas from liquid after gas-liquid separation, wherein most of the gas is carbon dioxide and a small amount of PO are separated and recycled after re-condensation, and the liquid mainly comprises reaction products of polycarbonate-polyether glycol, cyclic carbonate and unreacted raw material PO; then filtering and recovering the catalyst by a catalyst filter, flowing filtrate into a rectifying device, wherein the rectifying device is a falling film tower and is used together with a scraper evaporator, the filtrate firstly passes through the falling film tower to distill PO into a buffer tank for recycling, and then flows into the scraper evaporator to separate the polyhydric alcohol from the cyclic carbonate, and after the polyhydric alcohol and the cyclic carbonate are completely separated, the product parameters meet the industrial application and are respectively canned for later use.

Sampling and analyzing a polymerization reaction product flow, specifically, sampling and collecting the polymerization reaction product flow (polycarbonate-polyether polyol, cyclic propylene carbonate and unreacted epoxide) in a container, performing nuclear magnetic hydrogen spectrum characterization on a polymerization reaction product flow sample to calculate the proportion of a polymer and a cyclic micromolecule in a crude product, performing nuclear magnetic hydrogen spectrum test after purifying the polymer, and calculating to obtain the proportion of a polycarbonate chain link and a polyether chain link on a polymer main chain, wherein only two structures of the polycarbonate chain link and the polyether chain link are arranged on the polymer main chain, and the sum of the percentages of the two structures is 100%.

Number average molecular weight (M) of the polymer was measured by gel permeation chromatography_n) And polymer molecular weight polydispersity index (PDI).

By means of¹H-NMR (Bruker, DPX400, 400 MHz; pulse program zg30, waiting time d1:10s, 64 scans) determination of the incorporated CO in the resulting polycarbonate polyether polyols₂The amount of (carbonate chain-segment content) and the ratio of propylene carbonate (cyclic carbonate) to polycarbonate polyether polyol. The samples were dissolved in deuterated chloroform in each case.¹The relevant resonances in H-NMR (based on TMS 0ppm) were as follows

Wherein 5.0ppm and 4.2ppm are proton peaks on the last methyl and methylene of polycarbonate chain, 4.9ppm, 4.5ppm and 4.1ppm are proton peaks on the methylene and methylene of five-membered cyclic carbonate, and 3.5-3.8ppm are proton peaks on ether chain. The integrated Area of a peak at a certain ppm in the nuclear magnetic hydrogen spectrum is represented by capital letter A plus a numerical subscript, A being an abbreviation for the English writing Area of the Area, e.g. A_5.0Represents the integrated area of the peak at 5.0 ppm. According to the copolymerisation of the crude products¹The HNMR spectrum and the integral area of the relevant proton peak define the proportion (mole ratio) of carbonate chain segments in the copolymerization (F)_CO2) And cyclic carbonate content mass fraction (W)_PCwt), amount (by mass) of carbon dioxide inserted (M)_CO2) The calculation method of

Wherein the content of the first and second substances,

F_CO2＝(A_5.0+A_4.2-2×A_4.6)/[(A_5.0+A_4.2-2×A_4.6)+A_3.5]×100％；

W_PC＝102×A_1.5/[102×(A_5.0+A_4.2-2×A_4.6+A_1.5)+58×A_3.5]×100％；

M_CO2＝44×F_CO2/[102×F_CO2+58×(1-F_CO2)]×100％；

coefficient 102 is formed by CO₂The sum of the molar mass of (2) (molar mass 44g/mol) and the molar mass of PO (molar mass 58g/mol), the factor 58 being derived from the molar mass of PO.

Illustrative of the proportion of carbonate units (F)_CO2) And amount of carbon dioxide incorporation (M)_CO2) Is calculated as

When F is present_CO2When the content is 50%, that is, when the polymer contains 50% carbonate linkages, the amount of carbon dioxide incorporated M_CO2＝27.5％。

Conversely, when M_CO2When 30%, F_CO2If the mass fraction of carbon dioxide is required to be added to 56.5%, that is, 30% or more, the carbonate chain unit ratio is 56.5% or more.

Comparative example 1

Referring to chinese patent CN103403060B technical solution, polycarbonate-polyether polyol is continuously produced using the same raw materials, under the same reaction temperature conditions and within the same time as those of example 1, and the difference from example 1 is that comparative example 1 employs a DMC catalyst (double metal cyanide catalyst) according to WO0180994a1, comparative example 1 employs a tubular reactor having a single stage, and is externally provided with a cooling jacket, and the reaction temperature is controlled by the cooling jacket.

In particular, the ground and dried DMC catalyst (double metal cyanide catalyst) prepared according to example 6 of WO0180994A1 was suspended in resorcinol to achieve a catalyst concentration of about 2 wt% in resorcinol.

About 2 wt% of resorcinol with ground and dried DMC catalystThe suspension was conveyed at 80g/h by means of a diaphragm pump from a stirred feed supply container to a first mixer (cascade mixer 2S from Ehrfeld Mikrotechnik BTS GmbH, minimum gap between cascades 0.6 mm). Propylene oxide from the second feed vessel was transported to the mixer by means of an HPLC pump (97 g/h). In the mixer, mixing is carried out at a temperature of 20 ℃, wherein the resulting mixture remains unreacted. This mixed stream was conveyed with carbon dioxide (32 g/h from a cylinder with a dip tube by means of an HPLC pump) into a second mixer (cascade mixer 2S of EhrfeldMikrotechnik BTS GmbH, with a minimum gap of 0.6mm between cascades), in which the components were mixed at a temperature of 20 ℃. Here too, no reaction has taken place. The reaction mixture was sent from the second mixer to the tubular reactor. The tubular reactor has an outer diameter of 2.2mm and is controlled at a reaction temperature of 90-130 deg.C, specifically 120 deg.C. The volume of the tubular reactor was 45cm³. The average residence time of the components in the tubular reactor was 2 h. The pressure was regulated by means of a pressure regulating valve to maintain a constant pressure of 5MPa in the tubular reactor. The resulting product (mainly polyether carbonate polyol) was collected in a container.

The results of the test analysis of the polycarbonate-polyether polyols produced in example 1 and comparative example 1 are shown in Table 1.

Examination and analysis of the polycarbonate-polyether polyols produced in Table 1, example 1 and comparative example 1

Parameter(s)	Example 1	Comparative example 1
			Chain transfer agent to epoxy monomer molar ratio	1/50	1/50
Reaction temperature (. degree.C.)	120	120
			Epoxide conversion¹(％)	>99	50
Cyclic carbonate mass fraction W_PC ²	15	25
			Proportion of carbonate chain units (%)³	59	23
M_n ⁴(g/mol)	4550	1340
			PDI⁵	1.15	2.55

Note: 1 epoxide conversion: conversion of epoxide feedstock in the system after a given reaction time according to the crude product nuclear magnetic hydrogen spectrum (¹H NMR) is calculated; 2 molar ratio of cyclic carbonate, i.e. the molar percentage of cyclic small molecules (propylene carbonate) in the product stream of the polymerization reaction, according to the product nuclear magnetic hydrogen spectrum (¹H NMR) is calculated; 3 molar ratio of polycarbonate structure to polyether structure in the polymer chain unit according to the product nuclear magnetic hydrogen spectrum (¹H NMR) is calculated; 4 number average molecular weight (Mn) of the polymer, as determined by Gel Permeation Chromatography (GPC)Determining; 5 Polymer molecular weight polydispersity index (PDI) determined by Gel Permeation Chromatography (GPC). The measurement error of the above parameters is within +/-5%.

From the results in Table 1, we can see that the method of the present invention achieves the high catalytic activity under the conditions of higher chain transfer agent addition ratio (the chain transfer agent addition is 1/50 of epoxide mole number) and higher reaction temperature (120 ℃), and can prepare the polycarbonate polyether polyol with narrower molecular weight distribution and higher proportion of carbonate chain units. The principle lies in that on one hand, a mixed acid modified zinc-cobalt double metal cyanide complex catalyst is used as a reaction for polymerizing polycarbonate-polyether polyol to reduce the activation energy of generated polymers, on the other hand, a straight pipe type reactor is adopted to comprise a heating section group and a cooling section group, the cooling section group is arranged before materials enter a gas-liquid separation device to cool the materials, and the step (1) of separating the residual materials after the products of the polycarbonate-polyether polyol is obtained, so that the mass and heat transfer effects are better, the proportion of carbonate chain links is improved, the molecular weight distribution is narrower and more uniform, and the PDI value is smaller.

Example 2

Example 2 referring to example 1, except that the outlet end of the first heating zone group is connected to the inlet end of the first heating zone group by a pipe, so that part or all of the reaction liquid stream circulates in the first heating zone group, the reaction rate is accelerated, the reaction time is shortened, the pre-activation of carbon dioxide, an initiator and an epoxy monomer is promoted, and the proportion of polycarbonate chain links in the product is increased by controlling the induction period of the polymerization reaction.

Comparative example 2

Comparative example 2 referring to example 2 and comparative example 1, comparative example 2 employs the reaction process and reaction equipment of comparative example 1, but differs from comparative example 1 in that comparative example 2 employs the mixed acid-modified zinc-cobalt double metal cyanide complex catalyst of the present invention; different example 2 in that comparative example 2 used the tubular reactor of comparative example 1, the induction period of the polymerization reaction was not purposely controlled.

Examination and analysis of the polycarbonate-polyether polyols produced in Table 2, example 2 and comparative example 2

Parameter(s)	Example 2	Comparative example 2
			Chain transfer agent to epoxy monomer molar ratio	1/50	1/50
Reaction temperature (. degree.C.)	100	100
			Epoxide conversion¹(％)	>99	50
Cyclic carbonate mass fraction W_PC ²	10	15
			Proportion of carbonate chain units (%)³	85	65
M_n ⁴(g/mol)	4590	1340
			PDI⁵	1.12	2.19

Note: 1 epoxide conversion: conversion of epoxide feedstock in the system after a given reaction time according to the crude product nuclear magnetic hydrogen spectrum (¹H NMR) is calculated; 2 molar ratio of cyclic carbonate, i.e. the molar percentage of cyclic small molecules (propylene carbonate) in the product stream of the polymerization reaction, according to the product nuclear magnetic hydrogen spectrum (¹H NMR) is calculated; 3 molar ratio of polycarbonate structure to polyether structure in the polymer chain unit according to the product nuclear magnetic hydrogen spectrum (¹H NMR) is calculated; 4 polymer number average molecular weight (Mn), as determined by Gel Permeation Chromatography (GPC); 5 Polymer molecular weight polydispersity index (PDI) determined by Gel Permeation Chromatography (GPC). The measurement error of the above parameters is within +/-5%.

From the results in table 2, we can obtain that, as can be seen from the indexes such as the conversion rate of the epoxy monomer and the ratio of the carbonate chain units, the outlet end of the first heating section group in the method of the present invention is provided with a pipeline connected with the inlet end of the first heating section group, so that part or all of the reaction liquid stream circulates in the first heating section group, and the induction period of the polymerization reaction is controlled, thereby accelerating the reaction rate, shortening the reaction time, promoting the pre-activation of carbon dioxide, the initiator and the epoxy monomer, and increasing the ratio of the polycarbonate chain units in the product.

From the results of tables 1 and 2, we can obtain that examples 1 and 2 both use the mixed acid modified zinc-cobalt double metal cyanide complex catalyst of the present invention, but since the outlet end of the first heating stage train of example 2 has a pipe connected to the inlet end of the first heating stage train so that part or all of the reaction liquid stream circulates in the first heating stage train, the reaction rate is increased and the reaction time is shortened by controlling the induction period of the polymerization reaction, so that example 2 can react at a lower reaction temperature than example 1, the mass fraction of cyclic carbonate in the final product is further reduced, and the proportion of carbonate units is also increased from 59% of example 1 to 85% of example 2. Since comparative example 2 employs the mixed acid modified zinc-cobalt double metal cyanide complex catalyst of the present invention, it can be seen in tables 1 and 2 that the proportion of carbonate units in the product increased from 23% in comparative example 1 to 65% in comparative example 2.

However, since comparative example 1 and comparative example 2 both used the one-stage tubular reactor of the technical solution of Chinese patent CN103403060B, the obtained polycarbonate-polyether polyol had a polymer number average molecular weight M_nSignificantly lower than in examples 1 and 2.

Example 3

Example 3 referring to example 1, except that a first intermediate device is provided between the first heating zone group and the second heating zone group, the first intermediate device is connected with a carbon dioxide pipeline through a pipeline, so that the medium pressure in the straight tubular reactor is adjusted to 2-6 MPa; aimed at controlling the CO of the polymerization₂So that in the reaction there is sufficient CO₂Can participate in the polymerization reaction, thereby facilitating the reaction for producing the polycarbonate-polyether polyol.

Comparative example 3

Comparative example 3 referring to example 3 and comparative example 1, the difference between comparative example 1 is that comparative example 3 employs a mixed acid modified zinc-cobalt double metal cyanide complex catalyst of the present invention; the variant embodiment 3 consists in that no intermediate device is provided between the first heating section and the second heating section of the tubular reactor.

Examination and analysis of the polycarbonate-polyether polyols produced in Table 3, example 3 and comparative example 3

Parameter(s)	Example 3	Comparative example 3
			Chain transfer agent to epoxy monomer molar ratio	1/50	1/50
Reaction temperature (. degree.C.)	90	90
			Epoxide conversion¹(％)	>99	>99
Cyclic carbonate mass fraction W_PC ²	10	15
			Proportion of carbonate chain units (%)³	91	85
M_n ⁴(g/mol)	4550	4250
			PDI⁵	1.15	1.48

Note: 1 epoxide conversion: conversion of epoxide feedstock in the system after a given reaction time according to the crude product nuclear magnetic hydrogen spectrum (¹H NMR) is calculated; 2 molar ratio of cyclic carbonate, i.e. the mole percentage of cyclic small molecules (propylene carbonate) in the polymerization product streamAccording to the nuclear magnetic hydrogen spectrum of the product (¹H NMR) is calculated; 3 molar ratio of polycarbonate structure to polyether structure in the polymer chain unit according to the product nuclear magnetic hydrogen spectrum (¹H NMR) is calculated; 4 polymer number average molecular weight (Mn), as determined by Gel Permeation Chromatography (GPC); 5 Polymer molecular weight polydispersity index (PDI) determined by Gel Permeation Chromatography (GPC). The measurement error of the above parameters is within +/-5%.

From the results of Table 3, it can be seen from the two indexes of the proportion of cyclic carbonate and the proportion of carbonate chain units as by-products that the method of the present invention has a first intermediate device disposed between the first heating stage group and the second heating stage group, the first intermediate device being connected to a carbon dioxide pipeline through a pipeline, and CO controlling the polymerization reaction₂So that there is sufficient CO in the reaction₂Can participate in the polymerization reaction, thereby being beneficial to the reaction for generating the polycarbonate-polyether polyol and improving the proportion of polycarbonate chain links in the product.

Example 4

Example 4 referring to example 1, except that the straight tubular reactor of example 4 had two sets, one set having a tube inner diameter of 10mm as a laboratory apparatus and the other set having a tube inner diameter of 100mm as a pilot plant, the purpose was to see whether the method of the present invention had an amplifying effect by amplifying the size of the tube.

Comparative example 4

Comparative example 4 referring to comparative example 1, a difference from comparative example 1 is that the straight tubular reactor of example 4 has two sets, one set having a pipe inner diameter of 10mm as a laboratory apparatus and the other set having a pipe inner diameter of 100mm as a pilot plant, in order to see whether the method of comparative example 4 has an amplification effect by enlarging the size of the pipe.

Examination and analysis of the polycarbonate-polyether polyols produced in Table 4, example 4 and comparative example 4

As can be seen from example 4 of table 4, the method of producing a polycarbonate-polyether polyol according to the present invention has no amplification effect, and the molecular weight and molecular weight distribution of the polymer and the ratio of cyclic carbonate in the crude product, and the ratio of carbonate chain units in the polymer have no significant fluctuation (the absolute value of the ratio of the difference in fluctuation of the parameters obtained in the pilot plant with respect to the laboratory apparatus to the original value is less than 5%, for example, the fluctuation value of the ratio of carbonate chain units is-1%, and the absolute value of the ratio of the fluctuation value to the original value is 1/95-1%). While comparative example 4 has a certain amplification effect, the amplification effect in the comparative example is obvious, the carbonate chain ratio suddenly decreases from 40% to 10%, and the laboratory device is 4 times that of the pilot plant. The method provided by the patent has no influence on the conversion rate of epoxide and product indexes such as the content of carbonate chain links, the proportion of cyclic byproducts and the like of the polycarbonate polyether polyol by amplifying the reaction scale, namely the process has no amplification effect. The proportion of carbonate chain links in the polycarbonate polyether polyol produced by the process is higher than 90%, which shows that the process is a continuous flow synthesis equipment process which is beneficial to improving the carbon dioxide fixation amount of the product, accelerating the reaction speed and facilitating large-scale production. The principle of the method is that the concentration of the polycarbonate-polyether polyol serving as a product in a reaction system is maintained at a low content by continuously separating the polycarbonate-polyether polyol from the reaction system, so that the viscosity of the reaction system is proper in a variation range, the variation range of the material ratio of the reaction system is also proper, the pipelines of the straight tubular reactor can have the same inner diameter from front to back, and the mass and heat transfer capacities of the reaction equipment have better consistency from front to back; according to the invention, the gas pressure-supplementing feeding device is arranged between the heating sections of the straight-tube tubular reactor, so that on one hand, carbon dioxide is supplemented, on the other hand, materials in a reaction system are remixed by supplementing carbon dioxide, and the local enrichment of epoxy compounds is overcome, thereby effectively avoiding homopolymerization reaction between the epoxy compounds.

The above-mentioned embodiments are only used for illustrating the technical solutions of the present invention, and not for limiting the same; although the present invention has been described in detail with reference to the foregoing embodiments, it will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions of the embodiments of the present invention.

Claims

1. A method for improving the quality of polycarbonate-polyether polyol produced by a liquid phase method is characterized in that,

the method comprises the following steps:

2. The method of claim 1, wherein an outlet end of the first heating zone array has a conduit connected to an inlet end of the first heating zone array such that the reactant stream is circulated through the first heating zone array while maintaining a cyclic carbonate content of no greater than 30% in the reactant stream.

3. The method according to claim 1, wherein in the step (3), after the polymerization reaction product stream passes through the cooling section group, the polymerization reaction product stream is pumped from an outlet of the straight tubular reactor to a gas-liquid separator, the reaction liquid stream is pre-separated into a gas phase material and a liquid phase material by the gas-liquid separator, the gas phase material comprises carbon dioxide, the liquid phase material passes through a catalyst filter, after the catalyst nanoparticles are separated or recovered, the small molecule by-product cyclic carbonate is further separated by a rectifying device, so as to obtain the polycarbonate-polyether polyol product stream, and then the polycarbonate-polyether polyol product stream is pumped to a polycarbonate-polyether polyol storage tank for storage.

4. The method according to claim 3, wherein the rectification device comprises a falling film tower and a scraper evaporator, and the liquid phase material is subjected to a separation procedure through the falling film tower and the scraper evaporator in sequence, so as to separate out the cyclic carbonate as a small molecular byproduct, thereby obtaining the polycarbonate-polyether polyol product stream.

5. The process of claim 1 wherein a heat exchanger is disposed between the first heating zone train and the cooling zone train such that the polymerization product stream heats the feed pumped from the inlet end of the first heating zone train.

6. The method of claim 1, wherein the reaction solution is heated to 70-120 ℃ by flowing through a first heating section set, and then heated to 80-130 ℃ by flowing through a second heating section set.

7. The method of claim 1, wherein the heating section set comprises a first heating section set, a second heating section set and a third heating section set, the reaction solution flows through the first heating section set, the second heating section set and the third heating section set in sequence to carry out polymerization, the reaction solution flows through the first heating section set and is heated to 70-120 ℃, the reaction solution flows through the second heating section set and is heated to 80-130 ℃, and the reaction solution flows through the third heating section set and is heated to 90-150 ℃.

8. The process according to claim 1,6 or 7, wherein a first gas pressure supplementing feeding device is arranged between the first heating section group and the second heating section group, and the first gas pressure supplementing feeding device is connected with a carbon dioxide pipeline through a pipeline, so that the pressure in the straight tubular reactor is kept between 2 and 6 MPa.

9. The method of claim 1,6 or 7, wherein the heating section group comprises a first heating section group, a second heating section group and a third heating section group, a first gas pressure supplementing feeding device is arranged between the first heating section group and the second heating section group, and/or a second gas pressure supplementing feeding device is also arranged between the second heating section group and the third heating section group, and the first gas pressure supplementing feeding device and/or the second gas pressure supplementing feeding device are/is connected with a carbon dioxide pipeline through a pipeline, so that the medium pressure in the straight-tube tubular reactor is kept between 2 MPa and 6 MPa.

10. The method of claim 1, wherein the chain transfer agent is selected from any one or more of ethylene glycol, diethylene glycol, 1, 2-propanediol, 1, 3-propanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 1, 4-cyclohexanedimethanol, neopentyl glycol, glycerol, trimethylolpropane, trimethylolethane, 1,2, 4-butanetriol, 1,2, 6-hexanetriol, pentaerythritol, dipentaerythritol, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedioic acid, terephthalic acid, isophthalic acid, phthalic acid, trimesic acid, pyromellitic acid, catechol, resorcinol, and hydroquinone; the epoxide is at least one of ethylene oxide, propylene oxide, butylene oxide and epichlorohydrin.