WO2022160078A1

WO2022160078A1 - Induction system for epoxide continuous polymerization, inducer, and method for epoxide continuous polymerization

Info

Publication number: WO2022160078A1
Application number: PCT/CN2021/073687
Authority: WO
Inventors: 叶天; 秦承群
Original assignee: 万华化学集团股份有限公司
Priority date: 2021-01-26
Filing date: 2021-01-26
Publication date: 2022-08-04

Abstract

Disclosed are an induction system for epoxide continuous polymerization, an inducer, and a method for epoxide continuous polymerization. The induction system comprises the following components: an initiator, selected from a low-molecular-weight initiator or a reaction intermediate product low-molecular-weight initiator; a catalyst, selected from one or more of an alkali metal catalyst, an amine catalyst, a phosphonitrile catalyst, and a DMC catalyst; and a performance aid, selected from an active metal cyclic coordination compound, and preferably selected from a metalloporphyrin complex structure of formula I or a multidentate Salen ligand structure of formula II, the use amount of the performance aid accounting for 1-200 ppm, preferably 3-100 ppm, of the mass of a polyether product. The present application greatly reduces the problem of gradual increase in system viscosity and even process interruption caused by backmixing due to a broad molecular weight distribution in continuous polymerization.

Description

A kind of induction system for continuous polymerization of epoxide, inducer and method for continuous polymerization of epoxide

technical field

The present application relates to a method for continuous polymerization of epoxides, and in particular, to a method for preparing polyether polyol using a tubular reactor.

Background technique

Polyether polyols are a class of polyepoxides used in polyurethane materials. Its main structural formula is a polyhydroxy polymer of R-[C ₂ H ₄ 0] _m -[C ₃ H ₆ O] _n -H. Limited by the polymerization mechanism (polycondensation reaction), the polymerization process of polyether polyols has always been batch or semi-batch. Companies such as Bayer (Covestro) have successively developed a series of double metal cyanide catalysts (below). The semi-continuous and continuous synthesis technology of polyether based on DMC catalyst). However, these continuous synthesis processes all have certain defects, such as the limitation of molecular weight of the initiator and the inability to achieve ethylene oxide end capping, etc., which limit the development of the polyether industry.

US10258953B2 provides a method for continuously preparing polyether polyol by using DMC catalyst. The process adopts continuous stirred tank reactor (CSTR) mode, continuously adding initiator and epoxide, and continuously synthesizing polyether polyol with molecular weight less than 4000 . The process has the characteristics of maximizing the development of catalyst activity, lower energy consumption or even negative energy consumption, and stable product quality, but it is limited by the DMC catalyst itself, such as low molecular weight polyether polyol (molecular weight less than 300), ethylene oxide (hereinafter referred to as EO) end-capped/block polyether and other products cannot be prepared, and the process is easily shut down due to catalyst poisoning.

CN102753603B provides a continuous preparation of polyether polyols having an equivalent weight of up to 500 in the presence of a double metal cyanide catalyst. The first step of the reaction is carried out at a temperature of at least 150°C while controlling the hydroxyl content and unreacted alkylene oxide content of the reaction mixture within a certain range. A portion of the reaction mixture is withdrawn and allowed to react non-isothermally to consume unreacted alkylene oxide. No catalyst deactivation was observed with this method and no significant ultra-high molecular weight tail was produced. The invention effectively alleviates the defect that DMC catalyst cannot synthesize low molecular weight polyether polyol products in batch or conventional continuous polymerization, but because DMC catalyst is still used, ethylene oxide (hereinafter referred to as EO) end capping/block, lower Or higher molecular weight polyether polyol products, etc. still cannot be prepared.

CN103694465A discloses the synthesis technology for preparing polyether by continuous method, but still draws on the synthesis of continuous tank reactor. The biggest problem of this technology is the back-mixing problem. Considering polyether products, the focus is on molecular weight distribution, and high molecular weight polyethers in the system can also be used as initiators to polymerize with epoxide monomers. Therefore, the biggest problem of continuous tank reactors is high The formation of molecular weight polyether by-products cannot be avoided. With DMC catalyst, it can be largely avoided by using its "template effect", but there is still a by-product of ultra-high molecular weight polyether of about 1000 ppm.

CN109689728A discloses a method for continuous preparation of polyether in a tubular reactor, but a part of the catalyst used in this method adopts alkali metal system, and the process belongs to anionic polymerization. Since the catalyst is not activated in advance, the catalytic efficiency is extremely low, and high molecular weight cannot be prepared. Polyether, while the other part adopts DMC catalyst system, it is necessary to add high molecular weight polyether as a template agent in the feed composition, and the problem of ultra-high molecular weight polyether cannot be avoided.

In summary, traditional kettle-type continuous polymerization still cannot obtain polyether polyols with specific structures under high-purity raw materials and harsh anhydrous and non-toxic process conditions, while tubular reactors are generally used in alkali metal systems, which can only Low molecular weight system polyethers are prepared, and based on catalytic activity calculations, only ethylene oxide can be used for polymerization, so the development of continuous polymerization processes is limited. Although the batch synthesis reaction can obtain polyether products with different structures, it faces the problems of many reaction steps, complicated process and low efficiency in the process of synthesis and post-processing, which is not conducive to production scale-up.

In addition, in the continuous polymerization of polyethylene glycol (polyethylene oxide), there are patents that mention the use of microchannel reactors to synthesize corresponding polyether products. This is a new type of reactor that can greatly improve the mass transfer and heat transfer efficiency of the reactants. The microstructure in the microchannel reactor has a very large specific surface area, which can reach hundreds or even thousands of the specific surface area of the stirred tank. times. Moreover, the microchannel reactor has excellent heat transfer and mass transfer capacity, and the mass transfer efficiency is 10 to 100 times that of the tank reactor, which greatly improves the mixing efficiency of the reactants, and can achieve instant uniform mixing and efficient mixing of materials. Heat transfer can quickly reach a steady state. Compared with the traditional method, the microchannel reaction reduces the reaction time and material consumption, which is conducive to the smooth control of the strong exothermic reaction, and directly improves the intrinsic safety of the polymerization reaction process.

In CN106750244A, double metal cyanide was used as catalyst, and polyether polyol with number average molecular weight of 700-1000 was prepared by microchannel reactor. The catalyst is poisonous, and it is easy to cause heavy metal residues in the product. The initiator used must be a polyether polyol with a hydroxyl value equivalent of 150 to 300 obtained by polymerization, which undoubtedly increases the complexity of the process and cannot avoid the limitations of DMC catalysts. .

In CN108219129A, tristyrenated phenol is used as an initiator, and under the action of a basic catalyst, a microreactor is used to carry out the polymerization of ethylene oxide, and the continuous production of the product can be completed. In CN108033875A, a microreactor is used to build a system for continuous production of glycol ethers, which has small backmixing and high heat exchange efficiency, which can improve the conversion rate of epoxides, reduce the production of by-products, improve production efficiency, and reduce production energy consumption. , improve economic efficiency. CN109535411A provides a method for preparing polyethylene glycol with a single distribution in a microchannel reactor, but only uses ethylene oxide for polymerization, and does not obviously provide kinetic parameters. The yield is low and does not have great economic value, and there is a dead zone in the microchannel reactor, which inevitably leads to the accumulation of polymer polyether by-products. The above patents all focus on realizing the continuation of ethylene oxide polymerization and subsequent production, reducing the production of by-products and improving the reaction efficiency. So far, there is no process technology for realizing continuous polycondensation of epoxides in a real sense.

CN105949449A and CN102702503A disclose a method that a class of porphyrin or metal salen catalysts can be used to prepare a polyol containing a polyether segment with a narrow molecular weight distribution. This is a copolymerization process with propylene oxide in the presence of lactide and carbon dioxide. The pure metal coordination compound system or the pyridine-based cocatalyst with some conjugated electron pairs are respectively used to reduce the polymerization energy barrier of the propylene oxide monomer through the activation ability of the hole of the central metal atom. The mechanism of cationic polymerization is similar. The pure propylene oxide that is carried out first produces a large number of oligomers in this system, and the target polymer polycarbonate is formed after the addition of lactide or carbon dioxide. The above-mentioned patent discloses that the molecular weight distribution of the block polycarbonate polymer is 1.1-1.5, but when pure propylene oxide is used for polymerization in actual operation, the molecular weight distribution is generally greater than 1.3-1.4, and the molecular weight of the polymerized product cannot be controlled. Therefore, the use of pure porphyrin system does not significantly improve the problem of reducing the wide molecular weight distribution of pure polyether polyol, and further, in the continuous polymerization process, it is even more impossible.

Therefore, there is a need in the art for a new process for the continuous polymerization of epoxides.

SUMMARY OF THE INVENTION

The following is an overview of the topics detailed in this article. This summary is not intended to limit the scope of protection of the claims.

The purpose of the present application is to provide an induction system, an inducer and a method for the continuous polymerization of epoxides. The present application aims to realize the process of continuous synthesis of polyether with different catalytic systems. The present application avoids the complex operation process of the batch method, greatly improves the production efficiency, and greatly reduces the problem that the viscosity of the system is gradually increased or even the process is interrupted due to backmixing with a wide molecular weight distribution in continuous polymerization.

An induction system for continuous polymerization of epoxides, comprising the following components:

Starter, selected from small molecule starter, one or more selected from methanol, ethanol, ethylene glycol, propylene glycol, diethylene glycol, glycerol, pentaerythritol, ethylenediamine, sorbitol, glucose or sucrose or, a low-molecular-weight initiator of a reaction intermediate product, such as a polyether polyol system with a hydroxyl equivalent of 150-10,000;

Catalyst, selected from one or more of alkali metal catalyst, amine catalyst, phosphazene catalyst and DMC catalyst;

Performance assistants, selected from active metal cyclic coordination compounds, preferably from the metalloporphyrin complex structure of formula I or the polydentate Salen ligand structure of formula II,

Suitable -Ar are phenyl, m-methylphenyl, p-tert-butylphenyl, p-hydroxy-o-dimethylphenyl.

The alkali metal catalysts described in this application are preferably sodium metal, potassium metal, cesium metal, cesium hydroxide, sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, cesium carbonate, sodium salts of lower alcohols, and lower alcohols One or more of potassium salt or low-carbon alcohol cesium salt; Described amine catalyst is preferably imidazole type acetate, imidazole type methyl carbonate, quaternary amine acetate or quaternary amine methyl One or more of carbonates; the pKa of the phosphazene catalyst is 25 to 45, such as PZN-1 from parmcell; DMC catalysts are purchased or self-made, such as Zn-Co bimetallic complexes or Zn- Fe bimetallic complexes.

As a solution, when a DMC system is used, the initiator is a low-molecular-weight initiator of a reaction intermediate product, such as a polyether polyol system with a hydroxyl equivalent of 150-10,000; when a PZN system, an alkali metal system or an amine system is used , the initiator is a small molecule initiator.

Suitable performance aids include, but are not limited to:

An inducer for continuous polymerization of epoxide, comprising the reaction product of the induction system described in this application and epoxide.

In the inducer described in this application, the amount of epoxide used is 1% to 15% by weight of the inducer, preferably 3% to 10%.

A preparation method of the inducer described in the present application includes the following steps: the induction system described in the present application undergoes nitrogen replacement, dehydration and devolatilization, and then adds epoxide to induce the inducer to obtain the inducer.

In the preparation method of the inducer described in the present application, the temperature of the dehydration and devolatilization is 60-180°C, and the pressure is -0.05MpaG to -0.1MpaG.

In the preparation method of the inducer described in the present application, the dehydration and devolatilization time is 0.1 to 9 hours.

In the preparation method of the inducer described in the present application, the amount of epoxide used is 1% to 15% of the weight of the inducer, preferably 3% to 10%.

In the preparation method of the inducer described in the present application, the epoxide is ethylene oxide and/or propylene oxide.

In the preparation method of the inducer described in the present application, after the epoxide is added, the induction time is 0.5-60 min.

A method for continuous polymerization of epoxides, comprising the following steps: controlling the reaction temperature to be 100 to 200° C., the residence time to be 2 to 300 min, and the reaction pressure to be 0.1 to 3.5 MPaA; The selected small-molecule initiators are mixed and then enter into the tubular reactor for continuous reaction to prepare polyether products.

In the method for continuous polymerization of epoxides described in the present application, the amount of the catalyst contained in the inducer in the polyether product in terms of mass fraction is: 10-1000 ppm for the DMC system, 30-4000 ppm for the PZN system, and 30-4000 ppm for the alkali metal system. 0.05%～5%, amine system 0.1%～10%.

When the DMC system is used, the tubular reactor described in this application is preferably a multi-stage series tubular reactor, such as 2-stage and 3-stage, and a stage of the intermediate product of the multi-stage series-connected tubular reactor can be extracted for the preparation of the application. The above-mentioned inducer, the remaining intermediate product and the supplemented monomer and small molecule starter enter the latter section of the tubular reactor to continue the reaction to prepare the polyether product. For example, polyether polyols with hydroxyl equivalents of 150-10,000 are extracted for preparing induction systems; or for preparing block and multi-block polyether products.

In the method for continuous polymerization of epoxides described in the present application, the amount of the performance assistant contained in the inducer is 1-200 ppm, preferably 3-100 ppm, of the mass of the polyether product.

The hydroxyl value of the polyether product described in this application is 10-800 mgKOH/g, the molecular weight distribution is 1.02-1.06, and the nominal functionality is 2.1-3.8.

As a preferred solution, in the method for continuous polymerization of epoxides described in the present application, the polyether product is also subjected to post-treatment. The post-treatment is a well-known technique in the art, including but not limited to operations such as neutralization, dehydration, adsorbent treatment, crystallization, and filtration.

The existing technology relies on the difference of the collision probability to improve the difference in the reaction rates of the initiators with different molecular weights, and the present application is by adding performance assistants with different PO activation capabilities, which can improve the diffusion of initiators with different molecular weights and molecular sizes on the catalyst surface. , thereby improving catalytic activity and molecular homogeneity. The polymerization equipment uses a tubular reactor to realize the continuous polymerization of epoxide, which can effectively shorten the reaction period, improve the reaction efficiency, and reduce the production cost. Slowly, the molecular weight distribution of continuous polymerization is wider, which in turn leads to the gradual increase of the viscosity of the system and even the interruption of the process. In the present application, in the polymerization process, performance assistants must be added to reduce the activity of high molecular weight initiators, increase the activity of low molecular weight initiators, and promote the improvement of molecular homogeneity.

Beneficial effects of this application:

(1) Utilizing the advantage of less instantaneous reactants in the tubular reactor, it overcomes the shortcoming of high monomer residue and explosive polymerization in the polymerization reaction of epoxy compounds in conventional tank reactors, and avoids the easy generation of microchannel reactors. The dead zone leads to the problem of polymer by-products, which increases the safety and stability of the process and meets the requirements of current chemical safety operations;

(2) The use of extremely active performance additives greatly reduces the problem that the viscosity of the system will gradually increase or even cause the process to be interrupted due to back-mixing with a wide molecular weight distribution in continuous polymerization;

(3) With the help of continuous polymerization technology, the complicated operation process of batch method is avoided, and the production efficiency is greatly improved.

(4) The present application is generally applicable to the continuous synthesis technology of polyether, not limited to the catalytic system, and can effectively solve the defect that pure EO end-capping and block polymerization cannot be prepared in the continuous polymerization process.

Other aspects will become apparent upon reading and understanding the detailed description.

Detailed ways

The hydroxyl value test was carried out by the method of GB/T 12008.3-2009.

The molecular weight distribution was analyzed by gel chromatography, and PEG1000-10000 was used as the standard sample for calibration.

Example 1

The mixture containing 10wt% metal sodium, 50wt% metal potassium and 40wt% metal cesium was added to glycerol to prepare a 9.2wt% (the concentration of the catalyst in the induction system) solution, the amount of which was based on the mass fraction of the polyether product: 0.05wt%, at the same time add 1ppm (based on polyether products) performance additives (structure shown in the following formula), heat up to 100 ℃ in the preparation kettle, the pressure is -0.05MPaG, dehydrate for 0.1h, fill with nitrogen to 0.4MPaA, The ethylene oxide used for induction was 1 wt% of the total amount of the inducer, and the induction time was 0.5 min.

The above-mentioned inducer was added to the feed kettle, mixed with EO in a static mixer, and then added to a DN25 tubular reactor. The reaction temperature was 100 ° C, the residence time was 2 min, and the reaction pressure was 0.1 MPaA. According to the design molecular weight, EO and The feed mass flow ratio of the inducer was 183:1.

The actually obtained product has a hydroxyl value of 9.8 mgKOH/g, an equivalent molecular weight of 17173, a molecular weight distribution of 1.05, and a nominal functionality of 3.

Example 2

20wt% imidazole type acetate (imidazole-4-potassium acetate), 30wt% imidazole type methyl carbonate (1-methyl-3-propyl imidazole methyl carbonate), 50wt% quaternary amine acetic acid The mixture of salt (tetramethylaminomethyl sodium carbonate) was added to the initiator (20wt% methanol, 30wt% ethanol, 30wt% diethylene glycol, 20wt% ethylenediamine) to prepare 21wt% (catalyst in the induction system) concentration) solution, the amount of which is based on the mass fraction of the polyether product is 10wt%), while adding 200ppm (based on the polyether product) of the performance assistant (the structure is shown in the following formula), in the preparation kettle is heated to 180 ℃, The pressure was -0.1 MPaG, the dehydration was performed for 9 h, the propylene oxide used for induction was 15 wt% of the total amount of the inducer, and the induction time was 60 min.

The above-mentioned inducer was added to the feeding kettle, mixed with PO in a static mixer, and then added to a DN200 tubular reactor. The reaction temperature was 200 ° C, the residence time was 300 min, and the reaction pressure was 3.5 MPaA. According to the design molecular weight, PO and The feed mass flow ratio of the inducer was 1.1:1.

The hydroxyl value of the actually obtained product is 797 mgKOH/g, the equivalent molecular weight is 155, the molecular weight distribution is 1.02, and the nominal functionality is 2.2.

Example 3

A phosphazene catalyst with a pKa of 25 (parmcell PZN-1) was added to the initiator (30wt% sucrose, 70wt% ethylene glycol) to prepare a solution of 1.2wt% (the concentration of the catalyst in the induction system), and the dosage was The mass of the polyether-based product is 4000 ppm, and 3 ppm (based on the polyether-based product) of performance additives (the structure is shown in the following formula) is added at the same time, and the temperature is raised to 100 ° C in the preparation kettle, the pressure is -0.07 MPaG, dehydrated for 4 hours, and filled with nitrogen. To 0.4MPaA, 50wt% propylene oxide and 50wt% ethylene oxide used for induction are 8wt% of the total amount of the inducer, and the induction time is 30min.

The above-mentioned inducer was added to the feed kettle, mixed with 50wt% PO and 50wt% EO in a static mixer and then added to a DN100 tubular reactor, the reaction temperature was 130°C, the residence time was 150min, and the reaction pressure was 1.7MPaA, wherein By design molecular weight, the feed mass flow ratio of PO/EO mixture to inducer was 2:1.

The hydroxyl value of the actually obtained product is 401 mgKOH/g, the equivalent molecular weight is 532, the molecular weight distribution is 1.04, and the nominal functionality is 3.8.

Example 4

The commercially available DMC catalyst of Zn-Co (Huai'an Bad DMC-1) was added to the polyether intermediate product (hydroxyl equivalent 150g/mol, that is, molecular weight 315, hydroxyl value 356.2mgKOH/g) to prepare 1wt% (catalyst in the induction Concentration in the system) solution, its consumption is 1000ppm based on the quality of the polyether product, while adding 100ppm (based on the polyether product) performance assistant (structure shown in the following formula) in the preparation kettle to be heated to 60 ℃, the pressure is - 0.07MPaG, dehydration for 4h, propylene oxide used for induction was 8wt% of the total amount of the inducer, and the induction time was 10min.

The above-mentioned inducer was added to the feeding kettle, and mixed with PO and small molecular starter (a mixed starter of 80wt% propylene glycol, 10wt% pentaerythritol, 5wt% glucose, and 5wt% sorbitol) in a static mixer and then added two. Section DN25 tubular reactor, the reaction temperature is 130 ℃, the residence time is 150min, and the reaction pressure is 1.7MPaA. According to the designed molecular weight, the first section synthesizes a polyether intermediate product with a molecular weight of 315, and a part of it is used to configure the inducer. The mass flow ratio of PO: small molecule initiator: inducer is = 1:0.617:1, the remaining intermediate product enters the second-stage tubular reactor, and PO is controlled by adding PO and small molecular initiator : The feed mass flow ratio of the small molecule initiator: the inducer is =3.93:0.07:1, and the final polyether product is obtained.

The hydroxyl value of the actually obtained product is 100.7 mgKOH/g, the equivalent molecular weight is 1170, the molecular weight distribution is 1.06, and the nominal functionality is 2.1.

Example 5

The alkali metal catalyst adopts 5wt% cesium hydroxide, 30wt% sodium hydroxide, 65wt% potassium hydroxide, and is formulated into a 20wt% solution in the induction system. (based on polyether products) performance aid (structure shown in the following formula), the feed mass flow ratio of EO to inducer is 3:1. The remaining conditions are the same as in Example 1.

Example 6

The alkali metal catalyst adopts 20wt% sodium carbonate, 10wt% potassium carbonate, 70%wt cesium carbonate, and is formulated into a 19.3wt% solution in the induction system, and its dosage is 2% based on the mass fraction of the polyether product, EO and inducer The feed mass flow ratio is 9:1. The following formula is used for performance additives. The remaining conditions are the same as in Example 1.

The hydroxyl value of the actually obtained product is 9.7 mgKOH/g, the equivalent molecular weight is 17193, the molecular weight distribution is 1.04, and the nominal functionality is 3.

Example 7

The alkali metal catalyst adopts 30wt% of sodium methoxide, 30wt% of potassium methoxide and 40wt% of cesium methoxide.

The hydroxyl value of the actually obtained product is 9.9 mgKOH/g, the equivalent molecular weight is 17120, the molecular weight distribution is 1.06, and the nominal functionality is 3.

Example 8

The amine catalyst adopts imidazole acetate (sodium imidazole-4-acetate), and is prepared into a 0.30wt% solution in the induction system, and its dosage is 0.1wt% based on the mass fraction of the polyether product, and the ratio of PO and the inducer is 0.1wt%. The mass flow ratio of the feed was 2:1, the performance additives used were as shown in the following formula, and the remaining conditions were the same as those in Example 2.

The hydroxyl value of the actually obtained product is 798 mgKOH/g, the equivalent molecular weight is 150, the molecular weight distribution is 1.02, and the nominal functionality is 2.2.

Example 9

The amine catalyst adopts quaternary amine sodium methyl carbonate (tetramethylaminomethyl sodium carbonate), and is formulated into a 27wt% solution in the induction system, and its dosage is 5wt% based on the mass fraction of the polyether product, PO and induction The feed mass flow ratio of the agent is 4.4:1, the performance assistant used is shown in the following formula, and the remaining conditions are the same as those in Example 2.

The hydroxyl value of the actually obtained product is 799 mgKOH/g, the equivalent molecular weight is 149, the molecular weight distribution is 1.03, and the nominal functionality is 2.2.

Example 10

The phosphazene catalyst adopts a commercially available catalyst (parmcell PZN-2) with a pKa of 45, and is formulated into a solution of 90 ppm in the induction system, and its consumption is 30 ppm based on the quality of the polyether product. The remaining conditions are the same as in Example 3.

The actually obtained product has a hydroxyl value of 402 mgKOH/g, a converted molecular weight of 521, a molecular weight distribution of 1.04, and a nominal functionality of 3.8.

Example 11

The phosphazene catalyst adopts a commercially available catalyst (parmcell PZN-3) with a pKa of 35, and is formulated into a solution of 6000 ppm in the induction system, and its dosage is 2000 ppm based on the mass of the polyether product. The remaining conditions are the same as in Example 3.

The actually obtained product has a hydroxyl value of 400.9 mgKOH/g, equivalent molecular weight of 534, molecular weight distribution of 1.04, and nominal functionality of 3.8.

Example 12

DMC catalyst adopts the commercially available catalyst of Zn-Fe system (Senier, DMC-1), adds polyether intermediate product (hydroxyl equivalent 10000g/mol, namely molecular weight 21000, hydroxyl value 5.61mgKOH/g) to prepare the solution of 100ppm, The dosage is 10 ppm based on the mass of the polyether product. The remaining conditions are the same as in Example 4.

The hydroxyl value of the actually obtained product is 140.1 mgKOH/g, the equivalent molecular weight is 841, the molecular weight distribution is 1.03, and the nominal functionality is 2.1.

Example 13

The DMC catalyst adopts the commercially available catalyst of Zn-Fe system (Senier, DMC-1), and the inducer adopts the polyether intermediate product (hydroxyl equivalent 5000g/mol, that is, molecular weight 10500, hydroxyl value 11.22mgKOH/g) to prepare. A solution of 5000 ppm was prepared in the catalyst (corresponding to the mass fraction of the catalyst in the final product being 500 ppm). The remaining conditions are the same as in Example 4.

The hydroxyl value of the actually obtained product is 52.7 mgKOH/g, the equivalent molecular weight is 2235, the molecular weight distribution is 1.05, and the nominal functionality is 2.1.

Comparative Example 1

The alkali metal catalyst adopts 20wt% sodium carbonate, 10wt% potassium carbonate, 70wt% cesium carbonate, and is formulated into a 19.3wt% solution in the induction system, and the dosage is 2% based on the mass fraction of the polyether product. The mass flow ratio of the feed was 9:1, no performance assistant was used, and the remaining conditions were the same as those in Example 6.

The actual reaction process was interrupted. The hydroxyl value of the product actually obtained before the interruption was 9.9 mgKOH/g, the equivalent molecular weight was 17120, and the molecular weight distribution was 1.43.

Comparative Example 2

No performance aid was used, and the remaining conditions were the same as in Example 8. The actual reaction process was interrupted, and the hydroxyl value of the product actually obtained before the interruption was 798 mgKOH/g, the equivalent molecular weight was 153, and the molecular weight distribution was 1.32.

Comparative Example 3

No performance aid was used, and the remaining conditions were the same as in Example 10. The actual reaction process was interrupted. The hydroxyl value of the product actually obtained before the interruption was 400 mgKOH/g, the equivalent molecular weight was 540, and the molecular weight distribution was 1.40.

Comparative Example 4

No performance additives were used, and the remaining conditions were the same as in Example 4. The actual reaction process was interrupted. The hydroxyl value of the product actually obtained before the interruption was 100.7 mgKOH/g, the equivalent molecular weight was 1170, and the molecular weight distribution was 1.29.

Comparative Example 5

The catalyst adopts the performance assistant in Example 1 and 4-dimethylaminopyridine which accounts for 41wt% of the performance assistant. The remaining conditions are the same as those in Example 1, but the actual reaction process is interrupted, and the hydroxyl value of the product actually obtained by the molecular weight before the interruption is 8.7 mgKOH/g, equivalent molecular weight 19345, molecular weight distribution 1.68.

Comparative Example 6

The dosage of performance assistant was increased to 700ppm, and the remaining conditions were the same as in Example 1. The actual reaction process was interrupted. The hydroxyl value of the product actually obtained before the interruption was 8.9 mgKOH/g, equivalent to a molecular weight of 18910 and a molecular weight distribution of 1.74.

Claims

A kind of induction system for continuous polymerization of epoxide, it comprises the following composition:

Initiator, selected from small molecular initiator or reaction intermediate product low molecular weight initiator;

Catalyst, selected from one or more of alkali metal catalyst, amine catalyst, phosphazene catalyst and DMC catalyst;

The performance assistant is selected from active metal cyclic coordination compounds.
The induction system according to claim 1, wherein the small molecule initiator is selected from methanol, ethanol, ethylene glycol, propylene glycol, diethylene glycol, glycerol, pentaerythritol, ethylenediamine, sorbitol, glucose or one or more of sucrose.
The induction system according to claim 1, wherein the low molecular weight initiator of the reaction intermediate product is a polyether polyol system with a hydroxyl equivalent of 150-10,000.
The induction system according to claim 1, wherein the active metal cyclic coordination compound is selected from the metalloporphyrin complex structure of formula I or the polydentate Salen ligand structure of formula II,

-Ar is preferably phenyl, m-methylphenyl, p-tert-butylphenyl or p-hydroxy-o-dimethylphenyl.
The induction system according to claim 1, wherein the performance assistant is selected from one or more of the following substances:
The induction system according to claim 1 or 2, wherein, when a DMC system is used, the initiator is a reaction intermediate product low-molecular-weight initiator; when a phosphazene system, an alkali metal system or an amine system is used, the The initiator is a small molecule initiator.
An inducer for continuous polymerization of epoxide, comprising the reaction product of the induction system according to any one of claims 1-6 and epoxide.
The inducer according to claim 7, wherein the amount of epoxide used is 1%-15% by weight of the inducer, preferably 3%-10%.
The inducer according to claim 7 or 8, wherein the epoxide is ethylene oxide and/or propylene oxide.
A method for continuous polymerization of epoxides, comprising the following steps: controlling the reaction temperature to be 100-200° C., the residence time to be 2-300 min, and the reaction pressure to be 0.1-3.5 MPaA, the method described in any one of claims 7-9. Inducer, monomer and optional small molecule starter are mixed and then enter into the tubular reactor for continuous reaction to prepare polyether product.
The method according to claim 10, wherein the amount of the catalyst contained in the inducer in terms of mass fraction in the polyether product is: 10-1000 ppm for DMC system, 30-4000 ppm for phosphazene system, 0.05 ppm for alkali metal system %～5%, amine system 0.1%～10%.
The method according to claim 10 or 11, wherein the amount of the performance assistant contained in the inducer is 1-200 ppm, preferably 3-100 ppm, of the mass of the polyether product.
The method according to any one of claims 10-12, wherein, when a DMC system is used, the tubular reactor is a multi-stage series-connected tubular reactor, and a section of the intermediate product of the multi-stage series-connected tubular reactor is extracted for for the preparation of the inducer.