CN111484610B

CN111484610B - Preparation method of polycarbonate-polyether diol

Info

Publication number: CN111484610B
Application number: CN202010241343.2A
Authority: CN
Inventors: 罗铭; 毛红兵; 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: 2021-11-09
Anticipated expiration: 2040-03-30
Also published as: CN111484610A

Abstract

The invention discloses a preparation method of polycarbonate-polyether diol, wherein the number average molecular weight of the polycarbonate-polyether diol is 500-5000, and the preparation method comprises the following steps: (1) introducing epoxide, catalyst, initiator and carbon dioxide into a premixing tank for premixing, then introducing into a pipelined continuous reactor, and in the presence of the catalyst, contacting the initiator, the epoxide and the carbon dioxide in the pipelined continuous reactor for polymerization; (2) allowing part or all of the polymerization reaction product flow in the step (1) to flow through a cooling section group, separating out part of the polycarbonate-polyether glycol, and allowing the rest polymerization reaction product flow to continue to carry out polymerization reaction in a pipeline continuous reactor or to circulate to the step (1); wherein, the catalyst is modified by mixed acid during synthesis and is obtained by the reaction of water-soluble metal salts of zinc and cobalt in a water-soluble solvent.

Description

Preparation method of polycarbonate-polyether diol

Technical Field

The invention relates to the field of polycarbonate-polyether diol synthesis, in particular to a preparation method of polycarbonate-polyether diol.

Background

The polycarbonate-polyether diol structure simultaneously contains polycarbonate chain links and polyether chain links generated by homopolymerization of epoxy compounds, so that the polycarbonate-polyether diol structure has high Young modulus and flexibility, and becomes a raw material for preparing a polyurethane material. Consumption of CO due to the polymerization reaction for the production of polycarbonate-polyether diols₂The greenhouse gas carbon dioxide is used as a raw material and is converted into a polymer material, so that the environment protection, energy reduction and emission reduction are facilitated; the polymerization reaction is also often accompanied by cyclic carbonates as by-products, which are commonly used industrial products and can be isolated and purified for later sale.

At present, three main aspects of the problems of producing the polycarbonate-polyether diol exist in the production of the polycarbonate-polyether diol, and need to be solved, namely firstly, the content of a polycarbonate unit is improved, secondly, the molecular weight distribution of the polycarbonate-polyether diol is optimized, and thirdly, the amplification effect of producing the polycarbonate-polyether diol is solved.

Firstly, in the aspect of improving the content of the polycarbonate unit of the polycarbonate-polyether diol, the improvement of the aging resistance of the polycarbonate-polyether diol in the prior art is limited due to a plurality of defects in the catalyst, reaction equipment and production process in the prior art.

In terms of catalyst, when the mass ratio of the added catalyst to the added epoxy monomer is at least equal to or less than 1/1000 (namely the catalyst input is equal to or less than 1000ppm, namely 0.1 wt%), the total production cost and the cost of catalyst residue are relatively low, and the catalyst has economic value. 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 glycol 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 adding the initiator with higher proportion, the structural proportion of the polycarbonate in the structure of the synthesized polycarbonate-polyether diol 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 diols is particularly characterized by the need to overcome homopolymerization between epoxy compounds and to increase the content of carbonate units.

In addition, dihydric phenol and dicarboxylic acid with benzene ring structure are commonly used as the initiator for preparing the polycarbonate-polyether glycol by copolymerizing carbon dioxide and epoxide in the prior art because of higher activity. However, the benzene ring structure is easy to absorb ultraviolet rays, so that the product is yellow, and the polymer is easy to age due to free radicals generated by ultraviolet irradiation, but even if an initiator without the benzene ring structure is adopted, the initiator has a low carbonate unit content in the polycarbonate-polyether diol, has a high polyether chain link content, and also contains a high cyclic carbonate as a byproduct in the prior art, and the two factors are also the main reasons for the easy aging of the polymer. In addition, in the prior art, potassium hydroxide is used as a catalyst in the production of low molecular weight polyether glycol, so that the polyether glycol contains trace potassium ion residues, and polycarbonate polyol prepared by the polyether glycol also contains potassium ions, so that the polycarbonate polyol is yellow and has high chroma.

In terms of reaction equipment and production process, the process for synthesizing the polycarbonate-polyether glycol at present adopts a batch process. There are mainly the following problems:

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

2. The reaction of the polycarbonate polyether glycol is exothermic, and the reactor is required to have good heat exchange performance so as to ensure that the reaction does not fly. Too high a temperature leads to a low content of carbonate chain units, a broadening of the molecular weight distribution coefficient PDI and a higher proportion of cyclic carbonates as by-products, which reduces the quality of the product. Although a small number of continuous flow processes have been developed, there are problems: the amplification effect inevitably exists, which brings many uncertainties for further industrial application; 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, the tubular reactor is adopted at every point of the reaction system with uniform temperature, the cooling jacket is arranged outside the tubular reactor, the temperature control purpose can be realized, but the reaction system becomes viscous due to the generation of the product polycarbonate-polyether glycol, and the technical means adopted by the invention is that the first 20-60 percent of the length of the tubular reactor has the inner diameter of the tubular reactor of 1.1mm to <100mm, and the last 80-40 percent of the length has the 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.

Secondly, in optimizing the molecular weight distribution of the polymerization product polypropylene carbonate, compared with other conventional copolymerization reactions, the particularity of the copolymerization reaction of the polycarbonate-polyether glycol is that the carbonate unit content in the polycarbonate-polyether glycol is improved, the molecular weight distribution coefficient PDI of the product of the polycarbonate-polyether glycol is optimized, as the viscosity is increased along with the increase of the molecular weight of the polycarbonate-polyether glycol, the high-viscosity copolymerization reaction system limits the carbon dioxide to be polymerized into the polycarbonate-polyether glycol molecules, simultaneously, the heat transfer and mass transfer efficiency of the high-viscosity copolymerization reaction system is reduced, 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, the tailing phenomenon is generated, and the viscosity of the copolymerization reaction system is further increased, thus, under the conditions of the prior art, a high molecular weight polycarbonate-polyether diol often means a low carbonate unit content in the polycarbonate-polyether diol, and correspondingly, a high carbonate unit content polycarbonate-polyether diol is often accompanied by a low molecular weight, or the product of the polycarbonate-polyether diol has a broad molecular weight distribution coefficient PDI, and the polymer molecular weight distribution coefficient PDI (PDI) has a high value, or even has a significant tailing phenomenon.

Thirdly, in the aspect of solving the amplification effect of producing the polycarbonate-polyether glycol, the prior art has obvious amplification effect in reducing the production of the polycarbonate-polyether glycol due to a plurality of defects in the catalyst, reaction equipment and production process.

The prior art for synthesizing the polycarbonate-polyether polyol mostly adopts a batch process, although a small amount of continuous flow process is developed, the amplification effect is inevitable due to certain difference 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.

Because a high proportion of initiator, generally 1/50-1/90 of the mole number of epoxy monomer, is added, most of the catalysts in the prior art lose activity, and in addition, in the aspects of reaction equipment and production process, the batch process is mostly adopted in the current process for synthesizing the polycarbonate-polyether glycol. However, the reaction system becomes viscous due to the formation of the product polycarbonate-polyether diol, making it difficult to separate the catalyst from the polymerization system, which has led to the amplification effect of the prior art in the production of polycarbonate-polyether diols.

Compared with the common polymer, the polycarbonate-polyether diol has the particularity that the inventor finds that the polycarbonate-polyether diol has mutual entanglement and mutual restriction when the content of the polycarbonate unit is increased, the molecular weight distribution of the polycarbonate-polyether diol is optimized and the amplification effect of producing the polycarbonate-polyether diol is solved, the catalyst activity of the prior art is low, particularly, a high proportion of an initiator, generally 1/50-1/90 of the mole number of an epoxy monomer, is added to generate the product polycarbonate-polyether diol, a reaction system becomes viscous, the catalyst is difficult to separate from the polymerization reaction system, the mass transfer and heat conduction performance of reaction equipment is reduced, the content of the polycarbonate unit is increased, the molecular weight distribution is often wide, and is produced in the presence of amplification effects.

In summary, there is a need for a method capable of increasing the content of polycarbonate units and optimizing the molecular weight distribution of polycarbonate-polyether glycol, and solving the amplification effect of producing polycarbonate-polyether glycol, but there is no such solution.

Disclosure of Invention

In view of the foregoing, the present invention provides a method for preparing a polycarbonate-polyether diol. By organically combining and using a novel catalyst, improving reaction equipment and optimizing a production process, the amplification effect of producing the polycarbonate-polyether glycol is solved while the content of a polycarbonate unit is increased and the molecular weight distribution of the polycarbonate-polyether glycol is optimized.

In order to achieve the purpose, the invention provides the following technical scheme:

preparation method of polycarbonate-polyether diol, and structural formula of polycarbonate-polyether diol

The following were used:

the number average molecular weight of the polycarbonate-polyether glycol is 500-5000, the molecular weight distribution coefficient PDI is 1.0-3, the hydroxyl value is 22.4-224.4 mgKOH/g, R 'is selected from hydrogen atoms, methyl, ethyl and chloromethyl, R' is selected from hydrogen atoms, methyl, ethyl and chloromethyl, m1, m2, n1 and n2 are positive numbers, n1+ m2 to n1+ n2 are more than or equal to 1, and n3 is more than or equal to 0 and less than or equal to 8 integers;

the method comprises the following steps:

(1) introducing an epoxide, a catalyst, an initiator and carbon dioxide into a premixing tank for premixing, wherein the premixing pressure is 0.1-2 MPa, the premixing temperature is 0-50 ℃, the premixing time is 0-3 hours, and then introducing into a pipelined continuous reactor, wherein the pipelined continuous reactor comprises a heating section group and a cooling section group, the heating section group is arranged at the inlet end of the pipelined continuous reactor, and the cooling section group is arranged at the outlet end of the pipelined continuous reactor, so that the initiator, the epoxide and the carbon dioxide are contacted in the pipelined continuous reactor in the presence of the catalyst to form a copolymerization reaction system, and performing polymerization reaction to obtain a polymerization reaction product material flow containing the polycarbonate-polyether diol and an intermediate product;

(2) allowing part or all of the polymerization reaction product stream in the step (1) to flow through the cooling section group, separating part of the polycarbonate-polyether glycol to form a polycarbonate-polyether glycol product stream, and continuously performing polymerization reaction on the residual polymerization reaction product stream in the pipelined continuous reactor or recycling the polymerization reaction product stream to the step (1);

the catalyst is a zinc-cobalt double metal cyanide complex catalyst obtained by reacting water-soluble metal salts of zinc and cobalt in a water-soluble solvent, the catalyst is modified by mixed acid during synthesis, the mixed acid comprises 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, the concentration of the catalyst in the raw materials is 0.01-0.5 wt%, and the molar ratio of the initiator to the epoxy compound is 1: 10-1: 200; preferably, the concentration of the catalyst in the raw materials is 0.05-0.3 wt%, and the molar ratio of the initiator to the epoxy compound is 1: 50-1: 150; more preferably, the concentration of the catalyst in the raw materials is 0.05-0.2 wt%, and the molar ratio of the initiator to the epoxy compound is 1: 70-1: 130.

Preferably, the number average molecular weight of the polycarbonate-polyether glycol is preferably 1000-4000, and the molecular weight distribution coefficient PDI is preferably 1.0-2.5; more preferably 1000 to 3000, 1.0 to 2.5; more preferably 2000 to 3000, 1.0 to 2.5.

Preferably, the hydroxyl value of the polycarbonate-polyether diol is preferably 28-112.2 mgKOH/g; more preferably 56.1 to 112.2 mgKOH/g.

Preferably, at least two of epoxide, catalyst, initiator and carbon dioxide are introduced into a premixing tank, uniformly mixed and introduced into the pipelined continuous reactor, wherein the premixing pressure is 0.1-2 MPa, the temperature is 0-50 ℃, and the premixing time is 0-3 hours; preferably, the premixing pressure is 0.2-1.5 MPa, the temperature is 10-40 ℃, and the premixing time is 0.5-2.5 hours; more preferably, the premixing pressure is 0.5-1 MPa, the temperature is 10-30 ℃, and the premixing time is 1-2 hours.

Preferably, the reaction pressure in the pipeline continuous reactor is 1-10 MPa, the reaction temperature is 50-150 ℃, and the average residence time in the pipeline continuous reactor is 1-10 hours; preferably, the reaction pressure is 2-8 MPa, the reaction temperature is 80-120 ℃, and the average residence time in the continuous pipeline reactor is 2-6 hours; more preferably, the reaction pressure is 3-5 MPa, the reaction temperature is 80-100 ℃, and the average residence time in the continuous pipeline reactor is 3-5 hours.

Preferably, the initiator is selected from at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.

Preferably, the epoxide is at least one selected from ethylene oxide, propylene oxide, butylene oxide and epichlorohydrin.

Preferably, the organic acid is selected from any one or more of succinic acid, glutaric acid, phthalic acid, iminodiacetic acid, pyromellitic acid, and butanetetracarboxylic acid.

The invention has the following beneficial effects:

1. the method organically combines and uses a novel catalyst, improves reaction equipment and optimizes a production process to generate a synergistic effect, so that the method has the advantages that the content of carbonate units of the polycarbonate-polyether diol is increased, the proportion of by-product cyclic carbonate in a crude product is reduced, the molecular weight distribution of the product of the polycarbonate-polyether diol is narrow, the molecular weight polydispersity index (PDI) of a polymer is small, the numerical value is close to 1, no tailing phenomenon is basically observed in a molecular weight curve, and the method for producing the polycarbonate-polyether diol has no amplification effect. The method of the invention introduces epoxide, catalyst, initiator and carbon dioxide into a premixing tank for premixing by improving reaction equipment and optimizing production process, on one hand, the reaction system is uniform, on the other hand, the catalyst is activated, so that copolymerization reaction can be smoothly carried out after the catalyst enters a pipeline reactor, moreover, the method of the invention can continuously separate the polycarbonate-polyether diol from the copolymerization reaction system, therefore, the molecular weight distribution of the product of the polycarbonate-polyether glycol can be optimized, the mass transfer and heat transfer capacity and effect of the reaction equipment can be maintained and enhanced, the local overheating is avoided, thereby avoiding the generation of a large amount of polyether chain links and by-product cyclic carbonate caused by local overheating of reaction equipment in the prior art, and having no amplification effect in the method for producing the polycarbonate-polyether diol; 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 diol is synthesized, the carbon dioxide in a reaction system can be distributed more uniformly, the polycarbonate chain links with higher proportion are contained in the product polycarbonate-polyether diol, and the generation of the polyether chain links and the cyclic carbonate is also inhibited.

2. The applicant of the present invention also unexpectedly finds that the preparation method of the polycarbonate-polyether diol of the present invention has the characteristics of high ultraviolet aging resistance and low chromaticity, thereby solving the problems of low ultraviolet aging resistance and high chromaticity of the prior art, and in the aspect of the catalyst, the present invention realizes the catalytic polymerization reaction at a lower temperature and a higher initiator charge ratio by improving the activity and the selectivity of the catalyst; in addition, the method can continuously separate the polycarbonate-polyether diol 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, avoiding the generation of a large amount of polyether and cyclic carbonate caused by the local overheating of the reaction equipment in the prior art, improving the chain link content of the polycarbonate, ensuring that the polycarbonate-polyether diol has good ultraviolet aging resistance, being capable of more easily separating a catalyst from a polymerization reaction system, and avoiding the generation of a polymer with overlarge molecular weight due to implosion, so that the chromaticity of the polycarbonate-polyether diol is lower.

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.

Examples 1 to 11

The following were used:

the number average molecular weight of the polycarbonate-polyether diol is 500-5000, the molecular weight distribution coefficient PDI is 1.0-1.2, the hydroxyl value is 22.4-224.4 mgKOH/g, R 'is selected from hydrogen atoms, methyl, ethyl and chloromethyl, R' is selected from hydrogen atoms, methyl, ethyl and chloromethyl, m1, m2, n1 and n2 are positive numbers, n1+ m2 to n1+ n2 are more than or equal to 1, and n3 is more than or equal to 0 and less than or equal to 8 integers;

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 comprises 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.

The catalysts selected in examples 1-11 were prepared by the following method: weighing a certain mass of cobalt salt and zinc salt, dissolving in an aqueous solvent, and continuously stirring. Adding inorganic acid and organic acid, stirring for several hours at the temperature i), and continuously generating precipitate. And carrying out suction filtration on the turbid liquid, and drying to obtain a filter cake. And (3) carrying out reslurrying and washing on the filter cake by using an aqueous solvent at the temperature ii), stirring for several hours, carrying out suction filtration and drying to obtain the filter cake, and repeating the steps of reslurrying, washing and drying for many times at the temperature ii) until the pH value of the system liquid is 6-7. 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 examples 1-11, the catalyst micro-morphology was polyhedral particles with a particle size of 1-100 nm, specifically about 50nm, and the amorphous fraction of the catalyst was > 90%, and the amorphous fraction of the catalyst was characterized by X-ray diffraction (XRD).

The preparation method of the catalyst comprises the following steps: weighing a certain mass of potassium hexacyanocobaltate and zinc chloride, wherein the molar ratio of cobalt salt to zinc salt is 3:1, dissolving in water and tert-butyl alcohol 1:1 solvent, and continuously stirring. Adding hydrochloric acid and glutaric acid mixed acid, stirring at 80 deg.C for several hours, and generating precipitate continuously. And carrying out suction filtration on the turbid liquid, and drying to obtain a filter cake. Repulping and washing with water and a tert-butyl alcohol 1:1 solvent, stirring for several hours, carrying out suction filtration and drying to obtain a filter cake, and repeating the steps of slurrying, washing and drying twice until the pH value of the system liquid is 6-7. Further drying the solid product at 80-100 ℃ under vacuum to obtain a final catalyst, and processing the catalyst into powder particles by mechanical grinding under anhydrous drying conditions before use; the catalyst particle size was about 50nm and the amorphous fraction of catalyst was about 93%. The catalysts specifically used in examples 1 to 11 of the present invention were obtained by a more specific method for preparing the catalysts, but are not limited thereto.

In examples 1 to 11, the number average molecular weight of the polycarbonate-polyether diol is preferably 500 to 5000, and the molecular weight distribution coefficient PDI is preferably 1.1 to 1.2; more preferably 1000 to 4000, 1.1 to 1.15.

In examples 1 to 11, the hydroxyl value of the polycarbonate-polyether diol is preferably 28 to 112.2 mgKOH/g; more preferably 56.1 to 112.2 mgKOH/g; specifically 56.1 to 116.8 mgKOH/g.

In examples 1 to 11, the initiator is selected from at least one of succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, dodecanedioic acid.

In examples 1 to 11, the epoxide is selected from at least one of ethylene oxide, propylene oxide, butylene oxide, epichlorohydrin.

In examples 1 to 11, at least two of an epoxide, a catalyst, an initiator and carbon dioxide were introduced into a premixing tank, and after being uniformly mixed, the mixture was introduced into the continuous pipeline reactor, wherein the premixing pressure was 0.1 to 2MPa, the temperature was 0 to 50 ℃, and the premixing time was 0 to 3 hours; preferably, the premixing pressure is 0.2-1.5 MPa, the temperature is 10-40 ℃, and the premixing time is 0.5-2.5 hours; more preferably, the premixing pressure is 0.5-1 MPa, the temperature is 10-30 ℃, and the premixing time is 1-2 hours.

In examples 1 to 11, the reaction pressure in the continuous pipelined reactor was 1 to 10MPa, the reaction temperature was 50 to 150 ℃ and the average residence time in the continuous pipelined reactor was 1 to 10 hours; preferably, the reaction pressure is 2-8 MPa, the reaction temperature is 80-120 ℃, and the average residence time in the continuous pipeline reactor is 2-6 hours; more preferably, the reaction pressure is 3-5 MPa, the reaction temperature is 80-100 ℃, and the average residence time in the continuous pipeline reactor is 3-5 hours.

The reaction conditions of examples 1 to 11 are shown in Table 1.

TABLE 1 reaction conditions of examples 1 to 11 and comparative examples 1 to 2

The examination and analysis of the polycarbonate-polyether diols produced in examples 1 to 11 are shown in Table 2

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 polypropylene carbonate₂The amount of (carbonate chain unit content) and the ratio of propylene carbonate (cyclic carbonate) to polypropylene carbonate. The samples were dissolved in deuterated chloroform in each case.¹The relevant resonances in H-NMR (based on TMS ═ 0ppm) are as follows:

where 5.0ppm and 4.2ppm are attributable to polycarbonate chain segmentsThe last proton peaks on the methyl and methylene groups, 4.9ppm,4.5ppm and 4.1ppm, belong to the proton peaks on the methine and methylene groups in the five-membered cyclic carbonate, and 3.5-3.8ppm belong to the proton peaks on the 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 products¹H NMR spectrum and integral area of its associated proton peak, we define the proportion (molar ratio) of carbonate units 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) The calculation of (2):

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 the chinese patent CN103403060B technical solution, polycarbonate-polyether glycol was continuously produced using the same raw materials as in example 6, and the difference from example 6 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 type, and a cooling jacket is provided on the outside, 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 dodecanedioic acid such that a catalyst concentration of 0.99% by weight was achieved in the dodecanedioic acid.

A0.99% by weight suspension of dodecanedioic acid with the ground and dried DMC catalyst was conveyed at 80g/h by stirring from a first container to a first mixer (cascade mixer 2S from Ehrfeld Mikrotechnik BTS GmbH, minimum gap between cascades 0.6mm) by means of a diaphragm pump. 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 dip tube by means of an HPLC pump) into a second mixer (cascade mixer 2S of Ehrfeld Mikrotechnik 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 had an outer diameter of 2.2mm and was controlled at a reaction temperature of about 100 ℃. The volume of the tubular reactor was 45cm³. The average residence time of the components in the tubular reactor was about 3 hours. The pressure was regulated by means of a pressure regulating valve to maintain a constant pressure of about 3MPa in the tubular reactor. The resulting product (mainly polyether carbonate diol) was collected in a vessel.

The test analysis of the polycarbonate-polyether diol produced in comparative example 1 is shown in Table 2.

Comparative example 2

Comparative example 2 referring to example 1 and comparative example 1, comparative example 2 employs the reaction equipment and process 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.

The test analysis of the polycarbonate-polyether diol produced in comparative example 2 is shown in Table 2.

TABLE 2 examination and analysis of polycarbonate-polyether diols produced in examples 1 to 11 and comparative examples 1 to 2

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; the 2-ring carbonate molar ratio, i.e., the mole percentage of cyclic small molecules (propylene carbonate) in the polymerization product stream, is based on 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 distribution (PDI), as determined by Gel Permeation Chromatography (GPC), within + -5% of the above parameters.

From the results in Table 2, we can see that the process of the present invention achieves high catalytic activity under higher initiator addition ratio (1/50 where the initiator is added in mole of epoxide) and higher reaction temperature (150 ℃); example 1 in the same manner as comparative example 2 and comparative example 3 with the same initiator and the same molar ratio of initiator to epoxide, the reaction temperature was 100 ℃, but example 1 produced polycarbonate polyether glycol with a narrower molecular weight distribution and a higher proportion of carbonate units. The principle is that on one hand, a mixed acid modified zinc-cobalt double metal cyanide complex catalyst obtained by reacting water-soluble metal salts of zinc and cobalt in a water-soluble solvent is used as a reaction for polymerizing polycarbonate-polyether dihydric alcohol 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, a 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 product polycarbonate-polyether dihydric alcohol is obtained, so that the mass and heat transfer effect is better, the proportion of carbonate chain links is improved, the molecular weight distribution is more concentrated, and the PDI is smaller.

Example 12

Example 12 referring to example 6, example 12 employed the starting material and catalyst and reaction process of example 6 except that the initiator of example 12, epoxy monomer mole, was 1/50, the reaction temperature was 80 ℃, and there were two sets, one set being a laboratory set, and the inner diameter of the tube being 10mm, the other set being a pilot plant, and the inner diameter of the tube being 100mm, compared to the pipelined reactor of example 12, in order to see if the process of the present invention had an amplifying effect by amplifying the size of the tube.

Comparative example 3

Comparative example 3 referring to comparative example 1, comparative example 3 using the raw material and catalyst and reaction process of comparative example 1, different from comparative example 1 in that the initiator of comparative example 3, epoxy monomer, was 1/50 in moles, the reaction temperature was 80 ℃, and there were two sets of tubular reactors, 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 3 has an amplification effect by amplifying the size of the pipe.

TABLE 3 examination and analysis of the polycarbonate-polyether polyols produced in example 12 and comparative example 3

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. fraction of cyclic groups in the product stream of the polymerization reactionMole percent of propylene carbonate according to product nuclear magnetic hydrogen spectrum (C:)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 distribution (PDI), determined by Gel Permeation Chromatography (GPC). The measurement error of the above parameters is within ± 5%.

From Table 3 it can be seen that the process according to the invention for producing polycarbonate-polyether polyols has a smaller amplification effect, whereas comparative example 3 has a certain amplification effect, the proportion of carbonate units in the laboratory apparatus of comparative example 3 dropping abruptly from 38% to 15% in the pilot plant. The method provided by the patent has no great influence on the conversion rate of epoxide, the content of carbonate chain links of polycarbonate polyether diol, the proportion of cyclic byproducts and other product indexes, namely the amplification effect of the process is small. The proportion of carbonate chain links in the polycarbonate polyether diol produced by the process is higher than 90%, which shows that the process is beneficial to improving the carbon dioxide fixation amount of the product, accelerating the reaction speed and being easy for large-scale production. 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 front and the back of the pipeline reactor are provided with consistent inner diameters, and the front and the back of the mass transfer and heat transfer capacity of the reaction equipment are better consistent.

In addition, when the inventor of the present application conducts an ultraviolet aging resistance test on the polycarbonate-polyether diol, it is found that the yellowing rate of the polycarbonate-polyether diols of examples 1 to 12 is below 10%, which is much lower than that of the polycarbonate-polyether diol of the prior art, and the yellowing rate of the polycarbonate-polyether diols of comparative examples 1 to 2 is above 20%; in addition, the polycarbonate-polyether diols of examples 1 to 12 have a color of significantly lower than that of comparative examples 1 to 3 because the catalysts can be removed relatively easily.

The above description is only an embodiment of the present invention, and not intended to limit the scope of the present invention, and all equivalent modifications made by the present invention in the specification or other related fields directly or indirectly are included in the scope of the present invention.

Claims

1. A preparation method of polycarbonate-polyether diol is characterized in that the structural formula of the polycarbonate-polyether diol is as follows:

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 comprises 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, the pH value is 0-5, and the organic acid is selected from one or more of succinic acid, glutaric acid, phthalic acid, iminodiacetic acid, pyromellitic acid and butane tetracarboxylic acid.

2. The preparation method according to claim 1, wherein the concentration of the catalyst in the raw material is 0.01 to 0.5 wt%, and the molar ratio of the initiator to the epoxy compound is 1:10 to 1: 200.

3. The preparation method according to claim 2, wherein the concentration of the catalyst in the raw material is 0.05 to 0.3 wt%, and the molar ratio of the initiator to the epoxy compound is 1: 50 to 1: 150.

4. The preparation method according to claim 2, wherein the concentration of the catalyst in the raw material is 0.05 to 0.2 wt%, and the molar ratio of the initiator to the epoxy compound is 1: 70 to 1: 130.

5. The method according to claim 1, wherein the polycarbonate-polyether diol has a number average molecular weight of 500 to 5000 and a molecular weight distribution coefficient PDI of 1.1 to 1.2.

6. The method according to claim 5, wherein the polycarbonate-polyether diol has a number average molecular weight of 1000 to 4000 and a molecular weight distribution coefficient PDI of 1.1 to 1.15.

7. The method according to claim 1, wherein the polycarbonate-polyether diol has a hydroxyl value of 28 to 112.2 mgKOH/g.

8. The method according to claim 7, wherein the polycarbonate-polyether diol has a hydroxyl value of 56.1 to 112.2 mgKOH/g.

9. The preparation method according to claim 1, wherein at least two of the epoxide, the catalyst, the initiator and the carbon dioxide are introduced into a premixing tank, and are uniformly mixed and then introduced into the pipelined continuous reactor, wherein the premixing pressure is 0.1-2 MPa, the temperature is 0-50 ℃, and the premixing time is 0-3 hours.

10. The preparation method according to claim 9, wherein the premixing pressure is 0.2 to 1.5MPa, the temperature is 10 to 40 ℃, and the premixing time is 0.5 to 2.5 hours.

11. The preparation method according to claim 9, wherein the premixing pressure is 0.5 to 1MPa, the temperature is 10 to 30 ℃, and the premixing time is 1 to 2 hours.

12. The preparation method according to claim 1, wherein the reaction pressure in the continuous pipeline reactor is 1-10 MPa, the reaction temperature is 50-150 ℃, and the average residence time in the continuous pipeline reactor is 1-10 hours.

13. The preparation method according to claim 12, wherein the reaction pressure in the continuous pipeline reactor is 2-8 MPa, the reaction temperature is 80-120 ℃, and the average residence time in the continuous pipeline reactor is 2-6 hours.

14. The preparation method according to claim 12, wherein the reaction pressure in the continuous pipeline reactor is 3-5 MPa, the reaction temperature is 80-100 ℃, and the average residence time in the continuous pipeline reactor is 3-5 hours.

15. The method according to claim 1, wherein the initiator is at least one selected from succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedioic acid, and dodecanedioic acid.

16. The method according to claim 1, wherein the epoxide is at least one selected from the group consisting of ethylene oxide, propylene oxide, butylene oxide, and epichlorohydrin.

17. The method according to claim 1, wherein the molar ratio of the water-soluble inorganic acid to the organic acid is 1:10 to 10: 1.