Bisphenol A type low molecular weight polycarbonate polyether polyol and production process thereof

Abstract

The invention provides bisphenol A type low-molecular-weight polycarbonate polyether polyol and a production process thereof, and relates to the technical field of chemistry and chemical engineering. The production process is carried out in an integrated tubular reaction device, and comprises the following steps: premixing the epoxy compound, CO2, bisphenol A and a catalyst, and feeding the mixture into a reaction pipeline at one time to carry out polymerization reaction. In the polymerization reaction process, slow heating control and gas pressurization compensation are carried out, so that the molecular weight polydispersity index PDI of the bisphenol A type low-molecular-weight polycarbonate polyether polyol does not exceed 1.5, the carbonic ester chain link proportion FCO2 is greater than 55%, and in the Lab color system, the b value does not exceed 0.1. Through the regulation and control process, the problem of yellowing of the product generated in the one-step preparation process of the bisphenol A type low-molecular-weight polycarbonate polyether polyol can be solved, and the production efficiency is high. And the prepared product is narrow in molecular weight distribution, does not generate implosion, has no amplification effect, and is suitable for industrial large-scale production.

Description

Technical Field

[0001] This invention relates to the field of chemical engineering technology, and particularly to a bisphenol A type low molecular weight polycarbonate polyether polyol and its production process. Background Technology

[0002] Bisphenol A type low molecular weight polycarbonate polyether polyols are polycarbonate polyether polyols with a molecular weight of less than 3000. They are mainly synthesized from small molecule initiators, carbon dioxide, and epoxides via a bimetallic complex catalyst. Taking propylene oxide as an example, CO2 and propylene oxide, under the action of a small molecule initiator and a DMC catalyst, synthesize the main product: polycarbonate polyether polyol and the byproduct acrylate carbonate. The synthetic route is as follows: Using bisphenol A as an initiator, bisphenol A-type polycarbonate polyether polyols can be obtained. The aromatic ring and carbon-oxygen chain structures in the molecule endow the material with specific rigidity and toughness, thereby effectively improving the structure and properties of the polymer and giving downstream products better mechanical properties and thermal stability. It plays an important role in adhesives, rubber, surfactants and other fields.

[0003] The prior art CN115785435A discloses a one-step method for preparing polyether polyols. The one-step method specifically involves adding an epoxy compound, an initiator, and a catalyst to a reaction apparatus at room temperature in a single step to carry out the polymerization reaction. No further reaction raw materials are added during the reaction process, which significantly improves the reaction efficiency.

[0004] The inventors, using bisphenol A as an initiator, discovered severe yellowing of the product obtained in a one-step preparation of bisphenol A-type polycarbonate polyether polyols. This may be because the one-step method, with all raw materials added at once, easily triggers a rapid temperature rise during the polymerization reaction (e.g., a 5°C increase within 1 minute). When bisphenol A is exposed to high temperatures for an extended period, it is prone to thermal decomposition, for example, breaking down into several smaller molecules as shown by the dotted line in the following formula: ; The decomposition products of bisphenol A readily react with intermediates and byproducts of polymerization reactions to form yellow substances, such as dimethyl phthalate or quinone structures with chromophores, which cause the product to turn yellow and affect its downstream applications. Summary of the Invention

[0005] The purpose of this invention is to provide a bisphenol A type low molecular weight polycarbonate polyether polyol and its production process, which is suitable for large-scale industrial production of bisphenol A type low molecular weight polycarbonate polyether polyol. It can solve the problem of product yellowing caused by the one-step production process, effectively improve the total conversion rate and safety, and reduce production costs.

[0006] According to a first aspect of the present invention, a process for producing bisphenol A type low molecular weight polycarbonate polyether polyol is provided, which is carried out in an integrated tubular reactor having at least one reaction channel, the process comprising: A premixture is introduced into the reaction pipeline in one step, and CO2 at a first pressure is introduced; wherein the premixture is obtained by premixing the total amount of epoxy compound, bisphenol A and catalyst by introducing CO2. The premixture is heated and circulated within a reaction vessel to carry out a polymerization reaction, followed by separation to obtain a bisphenol A type low molecular weight polycarbonate polyether polyol. During the polymerization reaction, slow temperature control and gas pressure compensation are implemented to ensure that the polydispersity index (PDI) of the bisphenol A type low molecular weight polycarbonate polyether polyol does not exceed 1.5, and the carbonate repeating ratio F... CO2 Greater than 55%, and in L a b In the color system, b The value does not exceed 0.1.

[0007] Specifically, the polydispersity index (PDI) is determined by gel permeation chromatography (GPC). A lower PDI value indicates a narrower molecular weight distribution and more uniform product quality. More preferably, under the synergistic control of slow heating and gas pressurization compensation, the molecular weight polydispersity index (PDI) of the product can be controlled between 1.1 and 1.2 in this production process.

[0008] Specifically, L a b The values ​​of the color system can be obtained using a colorimeter, L a b In the color system, coordinate L L represents color brightness. =0 indicates black, L =100 indicates white. Coordinate a Indicates the position between red / magenta and green, a A negative value indicates green, a The indicator color is magenta, indicating a positive value. (Coordinate b) Indicates the position between yellow and blue, b Negative values ​​indicate blue, b A positive value indicates yellow. The higher the value, the more severe the yellowing of the sample. Furthermore, the product obtained through the embodiments of the present invention, a The value is less than 0.1, and b If the value is less than 0.1, the product is nearly colorless.

[0009] In an embodiment of the present invention, the slow heating control includes: controlling the temperature difference between the heating temperature of the reaction pipe and the temperature of the material inside the reaction pipe to not exceed 3~5°C, so that the material inside the reaction pipe is heated to 75~85°C and then undergoes a polymerization reaction.

[0010] In an embodiment of the present invention, gas pressure compensation includes: during the polymerization reaction, when the material temperature in the reaction pipeline rises sharply, CO2 gas with a second pressure value is introduced into the reaction pipeline until the material temperature in the reaction pipeline drops to 75~85°C. The criterion for determining a sharp rise in material temperature is a temperature rise of not less than 5°C within 1 minute. The second pressure value is 4~8 MPa and is greater than the first pressure value.

[0011] In an exemplary embodiment of the present invention, when performing gas pressurization compensation, the temperature of the CO2 gas is controlled to be 50~65°C.

[0012] In exemplary embodiments of the present invention, the first pressure value is 2-6 MPa, and the second pressure value is 4-8 MPa. For example, in one embodiment, the first pressure value is 3 MPa, and the second pressure value is 4 MPa. As another example, in another embodiment, the first pressure value is 5 MPa, and the second pressure value is 7 MPa.

[0013] In an exemplary embodiment of the present invention, a heat exchange medium circulates outside the reaction pipe to control the temperature of the material; during the polymerization reaction, the method further includes controlling the decrease in temperature of the heat exchange medium to be approximately equal to the increase in temperature of the material in the reaction pipe, so as to maintain the temperature of the material in the reaction pipe at 75~85°C.

[0014] In an exemplary embodiment of the present invention, the integrated tubular reaction apparatus includes a premixing unit and a reaction unit, wherein the premixed mixture is obtained by premixing in the premixing unit; the reaction unit includes a circulating pump and a plurality of reaction pipes, wherein the circulating pump is used to circulate the material within the plurality of reaction pipes, and the circulation flow rate of the circulating pump is 10-15 minutes to complete one cycle. Alternatively, the circulation flow rate of the circulating pump is 10 minutes to complete one cycle.

[0015] In an exemplary embodiment of the present invention, multiple reaction pipes are arranged in parallel. The feed end of each reaction pipe is connected to a liquid distributor via a connecting pipe, and the discharge end is connected to the circulation pump via a connecting pipe. One end of the liquid distributor is provided with a feed port connected to the premixing unit, and the other end is connected to the circulation pump. Each reaction pipe is provided with a gas injection port for CO2 to enter. The mixed products flowing out of multiple reaction pipes converge at the circulation pump, are pumped into the liquid distributor by the circulation pump, dispersed into multiple reaction pipes, and then reach the discharge end through the reaction pipes to complete one cycle.

[0016] In an exemplary embodiment of the present invention, during the polymerization reaction, the gas-liquid volume ratio in the reaction pipeline is controlled to be 1:1 to 4.

[0017] In an exemplary embodiment of the present invention, during the mixing process of the premixing unit, the temperature of the premixing unit is controlled at 0~40°C, the pressure at 0.1~2 MPa, and the premixing time at 1~2 h; when the material from the premixing unit is fed into the reaction unit, the temperature of the reaction pipeline is controlled at 35~45°C; and the reaction product density reaches 1.1~1.3 g / cm³. 3 And the change was less than 0.01 g / cm³ within 5 minutes. 3 The reaction is terminated at that time.

[0018] In an exemplary embodiment of the present invention, the catalyst contains only two metal elements besides impurities: zinc and cobalt. The catalyst is obtained by reacting water-soluble metal salts of zinc and cobalt in a water-soluble solvent, wherein the water-soluble metal salt of cobalt is a cyanide salt of cobalt. The catalyst is modified by a mixed acid during synthesis, wherein the mixed acid contains 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 between 0 and 5; the organic acid is selected from any one or more of succinic acid, glutaric acid, phthalic acid, iminodiacetic acid, pyromellitic acid, and butanetetracarboxylic acid, and the molar ratio of the water-soluble inorganic acid to the organic acid is 1:10 to 10:1.

[0019] According to a second aspect of the present invention, a bisphenol A type low molecular weight polycarbonate polyether polyol prepared according to the production process described in any one of the above claims is provided, wherein the structural formula of the bisphenol A type low molecular weight polycarbonate polyether polyol is represented by formula (1): Equation (1); In formula (1), R1 and R2 are selected from formula (2) or OH. Equation (2); In equation (2), 1≤n≤22, 1≤m≤39, and * indicates the connection position; The bisphenol A type low molecular weight polycarbonate polyether polyol has a number average molecular weight of 1000~3000 g / mol, a molecular weight polydispersity index (PDI) ≤ 1.5, a hydroxyl value of 35~110 mgKOH / g, and a carbonate repeating ratio F CO2 ≥45%.

[0020] Specifically, the carbonate repeating unit ratio F CO2 With the help of 1 The determination was performed using ¹H-NMR, based on the product. 1 Calculate the integral area of ​​the H-NMR spectrum and its associated proton peaks, and calculate the proportion (molar ratio) of carbonate repeating units F in the copolymerization reaction. CO2 The specific calculation method is as follows: 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%; where, A 5.0 A represents the integral area of ​​the peak at 5.0 ppm. 4.2 Indicates the integrated area of ​​the peak at 4.2 ppm; A 4.6 This represents the integrated area of ​​the peak at 4.6 ppm, and A 3.5 The value represents the integrated area of ​​the peak at 3.5 ppm; 5.0 ppm and 4.2 ppm represent the integrated areas of the proton peaks on the methylene and methyl groups of the polycarbonate chain; 4.9 ppm, 4.6 ppm, 4.5 ppm and 4.1 ppm represent the proton peaks on the methylene and methyl groups of the five-membered ring carbonate; and 3.5-3.8 ppm represent the proton peaks of the ether chain.

[0021] The beneficial effects of the bisphenol A type low molecular weight polycarbonate polyether polyol and its production process in this invention are as follows: (1) Compared with traditional processes, the present invention introduces the reaction raw materials in a one-step process, which effectively shortens the reaction time and improves production efficiency. Furthermore, it addresses the issue of bisphenol A decomposition leading to yellowing of the product caused by the rapid temperature increase introduced during the one-step product preparation process. This is achieved through refined slow heating control and gas pressurization compensation. Specifically, during heating, temperature-sensitive bisphenol A is protected to prevent decomposition and ensure the polymerization reaction is not affected. Additionally, when the reaction temperature rises sharply, carbon dioxide gas at a higher pressure is promptly introduced. By synergistically controlling the polymerization process through these two aspects, the yellowing of the product caused by reaction explosion and temperature runaway is effectively avoided, ensuring that the PDI of the obtained polyol product does not exceed 1.5, and b With a value not exceeding 0.1, the product is nearly colorless, effectively improving product quality and filling the technological gap in one-step synthesis of bisphenol A type polycarbonate polyether polyols.

[0022] (2) The production process of the present invention is carried out in an integrated tubular reactor, in which the material is continuously circulated. By designing specific premixing units and reaction units with specific structures and parameters, the polymerization reaction process is guaranteed to achieve sufficient gas-liquid heat conduction and gas-liquid-solid mixing. This, in conjunction with the reaction control parameters (temperature control, circulation speed control and gas compensation control), results in a narrow molecular weight distribution of the product, no scale-up effect, strong controllability of product molecular weight, stable production between batches, and high product quality. At the same time, the production process is safe, does not produce explosive polymerization, has no scale-up effect, and is suitable for large-scale industrial production. Attached Figure Description

[0023] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort.

[0024] Figure 1 This is a schematic diagram of an integrated tubular reactor for the production of bisphenol A type low molecular weight polycarbonate polyether polyols provided in an embodiment of the present invention. The black arrow indicates the direction of raw material flow, the green arrow indicates the direction of gas entry, the blue arrow indicates the direction of circulation in the pipeline reactor, and the red arrow indicates the direction of product flow.

[0025] Figure 2 for Figure 1 The schematic diagram of the reaction unit of the reaction device shows that the green part represents the gas-liquid mixing and heat conduction zone, and the red part represents the solid-liquid mixing zone.

[0026] Icons: 001-Propylene oxide; 002-Catalyst; 003-Small molecule initiator; 004-CO2 gas supply device; 005-Premixing unit; 006-Reaction unit; 007-Circulating pump; 008-Separation unit; 009-Purification unit; 010-Distillation unit; 101-Liquid distributor; 102-Carbon dioxide gas supply port; 103-Dispersion plate; 104-Static mixer; 105-Jacket; 106-Reaction pipeline. Detailed Implementation

[0027] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased commercially.

[0028] The following provides a detailed description of the bisphenol A-type low molecular weight polycarbonate polyether polyol and its production process according to embodiments of the present invention. Specifically, the bisphenol A-type low molecular weight polycarbonate polyether polyol is synthesized using bisphenol A as a small molecule initiator, along with propylene oxide and CO2, under the action of a DMC catalyst.

[0029] In this embodiment of the invention, the structural formula of the bisphenol A type low molecular weight polycarbonate polyether polyol is represented by formula (1): Equation (1); In formula (1), R1 and R2 are selected from formula (2) or OH. Equation (2); In equation (2), 1≤n≤22, 1≤m≤39, and * indicates the connection position; The number average molecular weight of bisphenol A type low molecular weight polycarbonate polyether polyol is less than 3000.

[0030] The present invention provides a production process for the above-mentioned bisphenol A type low molecular weight polycarbonate polyether polyol, which is carried out in an integrated tubular reactor. Please refer to [link to relevant documentation]. Figure 1 The integrated reaction device includes a premixing unit 005, a reaction unit 006, and a post-processing zone.

[0031] It should be noted that the one-step synthesis of bisphenol A type polycarbonate polyether polyols refers to the process of adding all the epoxy compound, bisphenol A, and catalyst into the reaction apparatus in a single step, with no further raw materials added during the subsequent reaction process except for the introduction of CO2. The epoxy compound is selected from one or more of ethylene oxide, propylene oxide, 2-epoxybutane, 1,4-epoxybutane, and epichlorohydrin. Preferably, in this embodiment, propylene oxide is selected as the epoxy compound.

[0032] Furthermore, the DMC catalyst used in this embodiment is a mixed acid-modified zinc-cobalt bimetallic cyanide catalyst. The catalyst, excluding impurities, contains only zinc and cobalt. The catalyst is obtained by reacting water-soluble metal salts of zinc and cobalt in a water-soluble solvent. The water-soluble metal salt of cobalt is a cyanide salt of cobalt. The catalyst is synthesized by modification with a mixed acid, which contains at least one organic acid and at least one water-soluble inorganic acid. The water-soluble inorganic acid is selected from dilute sulfuric acid and dilute hydrochloric acid, and has a pH value between 0 and 5. 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 molar ratio of the water-soluble inorganic acid to the organic acid is 1:10 to 10:1.

[0033] Please see Figure 1 and Figure 2 The premixing unit is equipped with a premixing device, which can be, for example, a premixing vessel. Raw materials are fed into the premixing unit for premixing. The premixed raw materials are then fed into the reaction unit 006. After the reaction is completed, the reaction products are fed into the next step for post-processing.

[0034] Specifically, in a preferred embodiment, the reaction unit 006 includes a reaction pipe 106, a liquid distributor 101, a circulating pump 007, a carbon dioxide injection port 102, a dispersion plate 103, and a jacket 105. Multiple reaction pipes 106 are provided, and these pipes are connected in parallel. Each reaction pipe 106 has a jacket 105 on its outer side. The temperature of the reaction pipe 106 is controlled by introducing heat exchange media such as steam, water, or heat transfer oil into the jacket 105. The space between the multiple reaction pipes 106 is filled with heat exchange media, and an insulation layer is provided outside the heat exchange media. The inlet ends of the multiple reaction pipes 106 converge at the liquid distributor 101 via connecting pipes, and the outlet ends converge at the circulating pump 007 via connecting pipes. The reaction mixture flowing out from the outlet end of the reaction pipe 106 enters from the inlet end of the reaction pipe 106 via the circulating pump 007, passes through the reaction pipe 106, and reaches the outlet end, completing one cycle.

[0035] Specifically, each reaction pipeline 106 is equipped with a carbon dioxide injection port 102 for CO2 to enter. The material circulation path formed by each reaction pipeline 106, connecting pipeline, and circulating pump 007 is the same.

[0036] More preferably, the number of reaction pipes 106 is 2 to 8, such as 4 or 6. The multiple reaction pipes 106 are independent of each other and each is equipped with an independently controllable valve. By independently controlling each reaction pipe 106, if the temperature of a particular reaction pipe 106 becomes too high or other adverse conditions occur, timely individual control can be implemented to avoid affecting the entire reaction process.

[0037] More preferably, the center-to-center distance between two adjacent reaction pipes 106 is less than or equal to twice the inner diameter of the reaction pipe 106. More preferably, the length-to-diameter ratio of the reaction pipes 106 is 10 ≤ L: d ≤ 40. In the production process of bisphenol A type low molecular weight polycarbonate polyether polyol, a tubular reaction device is used. If the length-to-diameter ratio of the reaction pipes is too large, it is not conducive to dispersing the generated reaction heat, easily leading to the decomposition of polyester chains and yellowing of the product. If the length-to-diameter ratio of the reaction pipes is too small, the center position is too far from the pipe wall, resulting in a large temperature difference and a wider molecular weight distribution. Simultaneously, the continuous generation of heat during the reaction process will raise the temperature of the reaction system. The reactor needs to release the heat generated in the material in a timely manner. When the flow rate is constant, the liquid needs to complete circulation within a specified time to release heat and perform gas-liquid mass transfer. The length and center-to-center distance of the reaction pipes 106 ensure sufficient heating reaction time and meet the requirements of production efficiency.

[0038] For further recommendations, please refer to [link / reference]. Figure 2 As shown, the reaction conduit 106 includes a dispersion plate 103 and a gas-liquid mixing heat conduction zone ( Figure 2 (the green part in the image) and the solid-liquid mixing zone ( Figure 2 (The red part in the image). The dispersant plate 103 is used to disperse and control the material in the gas-liquid mixing heat conduction zone, dispersing it into liquid droplets for mass and heat transfer without contacting the pipe wall. The solid-liquid mixing zone is used to realize the real-time mixing and polymerization reaction of the catalyst and the epoxy compound. After the material in the reaction pipe 106 is dispersed by the dispersant plate 103, it flows from the gas-liquid mixing heat conduction zone to the solid-liquid mixing zone, and then is circulated back to the dispersant plate 103 by an external circulation pump and flows back to the gas-liquid mixing heat conduction zone. A static mixer 104 is provided in the solid-liquid mixing zone, and the static mixer 104 has a portion extending into the gas-liquid mixing heat conduction zone. The dispersant plate 103, the gas-liquid mixing heat conduction zone and the static mixer portion in this zone, the loop between the reaction pipe 106 and the circulation pump 007 together constitute the gas-liquid mixing heat conduction path, so that the mixture with low CO2 content in the reaction unit can redissolve CO2, while heat exchange occurs in the gas-liquid mixing heat conduction zone. The loop between the static mixer 104, the reaction pipeline 106, and the circulating pump 007 together constitutes a solid-liquid mixing path, so that the solid catalyst is uniformly dispersed in the epoxy compound, while dispersing the generated heat of reaction, reducing the temperature difference between the center temperature and the pipe wall in the reaction pipeline, and avoiding the formation of a burst point.

[0039] Further preferably, the length of the gas-liquid mixing heat conduction zone accounts for 20% to 50% of the length of the reaction pipe to ensure sufficient gas-liquid mass transfer efficiency.

[0040] More preferably, during the polymerization reaction, the gas-liquid volume ratio within the reaction pipe 106 is controlled to be 1:1 to 4. For example, the gas-liquid volume ratio within the reaction pipe can be 1:1, 1:2, or 1:4. It is understandable that, for example, if the volume of the reaction pipe is 8L and 4L of material is introduced, the gas-liquid volume ratio is 1:1. By controlling the gas-liquid volume ratio within the reaction pipe, a suitable gas-liquid ratio is ensured. A low gas-liquid ratio not only leads to poor mass and heat transfer efficiency in the CO2 region, resulting in a lower ester content and a yellowing color, but also easily causes an increase in the heat of generation during the reaction, increasing the difficulty of temperature control and making explosive polymerization highly likely.

[0041] Preferably, the dispersing plate 103 is positioned 10-50 mm from the top of the reaction pipe 106, and has multiple dispersing holes. By using the dispersing plate 103, the reactants can be uniformly dispersed and flow down in droplets at the end, increasing the mass and heat transfer area. Combined with the static mixer 104 and circulating pump 007 built into the reaction pipe 106, the entire circulating dispersion system can replace the traditional stirring process, ensuring continuous mixing of the reactants during circulation. Simultaneously, the dispersing plate 103 effectively facilitates better gas-liquid mass transfer of the reactants in the gas region and releases excess heat.

[0042] Further preferably, a temperature sensor is installed inside the reaction pipe 106, and a density detector is installed at the outlet. The jacket temperature is adjusted according to the material density and the internal temperature of the reactor to control the reaction rate. Specifically, in one embodiment, temperature sensors are installed in the middle and bottom of the reaction pipe 106 to more comprehensively monitor the temperature inside the reaction pipe 106.

[0043] The production process of bisphenol A type low molecular weight polycarbonate polyether polyol provided in this embodiment of the invention includes the following steps: (1) At a temperature of 0~40℃, the entire amount of epoxy compound, bisphenol A, and catalyst are added to the premixing unit 005 at one time, and CO2 is introduced for mixing to obtain a premix. Specifically, propylene oxide 001 is first added to the premixing vessel, then a fixed amount of small molecule initiator 003 and DMC catalyst 002 are added to the premixing vessel, and then carbon dioxide is supplied to the premixing vessel through the CO2 supply device 004. Preferably, the temperature of the premixing unit is 40℃, the carbon dioxide pressure is 0.1~2MPa, and the premixing time is 1~2h. More preferably, the premixing time is 1h.

[0044] (2) The premixed material is fed into each reaction pipe 106 in the reaction unit in one go through the conveying pipe. When the raw material enters the reaction pipe 106, the reaction unit is controlled to meet the following conditions: the temperature of the reaction pipe 106 is 35~45℃ and the carbon dioxide pressure is 0.1-0.5MPa. During the feeding process, the temperature is low to avoid decomposition of the raw material.

[0045] (3) Once the raw materials have completely entered the reaction unit, the feeding is complete. Carbon dioxide is supplied through the carbon dioxide supply port 102, and the CO2 pressure is controlled at a first pressure value of 2~6 MPa, more preferably, the CO2 pressure is controlled at 3 MPa. When the pressure is too low, a solenoid valve is used to automatically supply carbon dioxide through the carbon dioxide supply port 102 to replenish the pressure.

[0046] (4) Turn on the circulating pump 007, adjust the temperature of the heat exchange medium in the jacket 105, and slowly heat up the material in the reaction pipe 106 to the reaction temperature, which is 80±5℃. For example, the reaction temperature is 80℃, 78℃, etc. Specifically, the slow heating process includes controlling the temperature difference between the heat exchange medium in the jacket 105 and the material in the reaction pipe 106 to not exceed 3~5℃. Preferably, the temperature difference between the heat exchange medium in the jacket 105 and the reaction pipe 106 is controlled to be 3℃, and the temperature of the reaction pipe 106 is slowly increased until the temperature of the reaction pipe 106 reaches 80±5℃. More preferably, during the heating process, the temperature value measured by the temperature sensor installed in the middle of the reaction pipe 106 is used as the temperature of the reaction pipe 106. By controlling the slow heating, it is possible to avoid the material temperature from rising too quickly, causing bisphenol A to decompose into small molecules, which would affect the polymerization reaction effect and product quality.

[0047] (5) After heating to 80±5℃, the polymerization reaction is carried out. The circulating pump 007 is kept on, and the temperature inside the reaction pipe 106 is monitored. When the temperature of the reaction pipe 106 rises, the temperature of the heat exchange medium in the jacket 105 is correspondingly reduced. The reduction in temperature of the medium in the jacket 105 is approximately equal to the increase or decrease in temperature of the reaction pipe 106, so as to keep the material temperature at 80±5℃. Specifically, in the above process, the temperature value measured by the temperature sensor installed at the bottom of the reaction pipe 106 is taken as the temperature of the reaction pipe 106. The temperature inside the reaction pipe 106 often rises due to the exothermic reaction of the raw materials. When the temperature rises, the temperature of the heat exchange medium in the jacket 105 is reduced to keep the temperature of the reaction system relatively constant.

[0048] Simultaneously, gas pressure compensation control is implemented during the aforementioned polymerization reaction. The steps of gas pressure compensation control include: during the polymerization reaction, when the material temperature in the reaction pipe 106 rises sharply, CO2 gas at a second pressure value is introduced into the reaction pipe 106 until the material temperature in the reaction pipe 106 drops to 80±5℃. The criterion for determining a sharp rise in material temperature is a temperature rise of not less than 5℃ within 1 minute. The second pressure value is 4~8MPa, and is greater than the first pressure value.

[0049] Specifically, when the polymerization reaction is vigorous or the reaction rate in a localized area is too fast, the material temperature can rise sharply. When a sharp rise in temperature is detected within the reaction pipe, purified CO2 gas from the carbon dioxide purification unit is introduced into the reaction pipe 106 through the carbon dioxide inlet 102 until the material temperature within the reaction pipe 106 drops to 80±5°C. The criterion for a sharp rise in material temperature is a temperature increase of at least 5°C within 1 minute. Preferably, the temperature of the purified CO2 gas is 50-65°C, for example, 50°C, 55°C, or 60°C. For example, in one embodiment, if the reaction temperature is 80°C and the material temperature within the reaction pipe rises above 85°C within 1 minute, purified CO2 gas at 60°C is introduced until the temperature within the reaction pipe drops to 80°C. By introducing low-temperature, high-pressure CO2 gas, the material can be rapidly cooled, reducing the risk of explosive polymerization. Furthermore, the introduction of higher-pressure CO2 gas greatly increases the gas-liquid mass transfer within the pipeline. By coordinating this step with the aforementioned slow heating process, the yellowing of the product can be effectively avoided.

[0050] The production process described in the above embodiment employs a passive feedback control strategy based on a fixed threshold to regulate temperature during the polymerization reaction stage. The core drawback of this strategy lies in its inherent control lag; that is, the control measures (gas pressurization compensation) are only triggered after the system temperature has fluctuated drastically (rising by no less than 5°C within 1 minute).

[0051] For highly exothermic reactions like polymerization, even a brief temperature overshoot is enough to trigger the decomposition of some heat-sensitive initiators (bisphenol A), leading to the formation of impurities such as quinone structures with chromophores, ultimately causing the product to yellow (b The viscosity increases and the molecular weight distribution broadens (PDI increases). More importantly, this control strategy fails to fully consider and utilize a crucial physicochemical relationship in the polymerization process: the dynamic nonlinear coupling between material viscosity and system thermal stability. In the early stages of the reaction, the material viscosity is low, and heat is easily diffused; however, as the degree of polymerization increases, the system viscosity rises sharply, which significantly deteriorates heat conduction and gas mass transfer efficiency, leading to an exponential increase in the risk of localized heat accumulation. The constant temperature change rate threshold relied upon by the original control strategy cannot adapt to this evolution of system risk driven by viscosity changes, becoming too sluggish in the later stages of the reaction. This results in a loss of the ability to proactively and precisely control the process, failing to fundamentally prevent thermal runaway.

[0052] To overcome the aforementioned technical deficiencies, in a preferred embodiment of the present invention, a feedforward-feedback collaborative adaptive control method based on viscosity prediction is provided for the slow temperature rise control and gas pressurization compensation steps in the polymerization reaction process. This method further improves the precision control level of the process, reaction safety, and consistency of the final product quality. This method overcomes the inherent hysteresis of feedback control strategies based on fixed temperature change thresholds, thereby achieving predictive and forward-looking control of the reaction temperature.

[0053] It is understandable that, in order to achieve proactive control, it is essential to understand the key state variables that can predict future risks of the system, and material viscosity is precisely such a core variable. Considering that directly and in real-time measuring viscosity in a high-temperature and high-pressure reaction environment is technically challenging and costly, a soft-sensor model is adopted, using easily and accurately measurable process parameters to indirectly estimate and predict viscosity.

[0054] Specifically, during the polymerization reaction, slow temperature control and gas pressurization compensation are implemented to ensure that the molecular weight polydispersity index (PDI) of the bisphenol A type low molecular weight polycarbonate polyether polyol does not exceed 1.5. This includes: firstly, acquiring the material temperature sequence in the reaction pipeline in real time through a data acquisition system. Pressure sequence Circulating pump flow rate and material density sequence Multiple data streams. Then, based on the material temperature sequence within the reaction pipeline. Pressure sequence Circulating pump flow rate and material density sequence Viscosity dynamic prediction is performed to obtain the predicted viscosity of the material at a future time Δt. Specifically, this data is input into a dynamic viscosity prediction model, which calculates the material viscosity a short time Δt later using an improved empirical formula that couples the Arrhenius equation with Flory-Huggins theory. In this way, a virtual online viscosity sensor is deployed in the production process, quantitatively and digitally representing the key physical quantities that originally characterized the degree of polymerization and thermal stability. This provides a forward-looking indicator that can predict the trend of changes in the system's thermal stability, offering a crucial data foundation for subsequent adaptive control decisions. This shifts the focus of control from the lagging temperature phenomenon to the deeper, essential state of the material.

[0055] This step can be represented as: in, Representing the future Predicted viscosity at time; As a pre-exponential factor, for the bisphenol A type polycarbonate polyether polyol system involved in this invention, as a non-limiting example, its value can be 1×10⁻ 5 The specific values ​​need to be obtained through experimental calibration within the range of Pa·s to 1×10⁻³ Pa·s; It is the apparent flow activation energy; It is the ideal gas constant, which is a well-known physical constant, usually taken as 8.314 J / (mol·K); , and These are the real-time temperature, pressure, and density at time t, respectively. and It is a pressure and density sensitivity index calibrated based on experimental data; This is the density influence coefficient, which, as a non-limiting example, can be selected in the range of 0.5 cm³ / g to 5.0 cm³ / g; This refers to the initial density of the reactants. In practical applications, the parameters in the above model... , , , , All parameters were calibrated through a series of offline experiments to ensure the accuracy of the predictions. For example, in a specific but non-limiting embodiment, the apparent flow activation energy... The pressure sensitivity index can be taken in the range of 20-80 kJ / mol. It can be used in the range of 0.01-0.1 MPa. -1 The value ranges from 100 to 100, while the density sensitivity index... It can take values ​​in the range of 1.0-3.0.

[0056] Next, regarding the future The predicted viscosity of the material at any given time is used for adaptive risk assessment and dynamic threshold calculation to obtain the adaptive temperature change rate threshold for the current time. The fixed temperature change threshold in the original control strategy cannot match the system risk that dynamically changes throughout the entire cycle. Therefore, a new control strategy is adopted to enable the sensitivity of the control system to automatically increase as the risk increases.

[0057] Specifically, the predicted viscosity output from the previous step... As input, a specially designed Sigmoid function is substituted to calculate the adaptive temperature change rate threshold used to trigger gas pressurization compensation at the current moment. This threshold is inversely correlated with the predicted viscosity. Thus, the physicochemical principle that higher viscosity leads to worse system thermal stability is transformed into a specific, actionable dynamic control parameter. This endows the control system with the ability to sense and assess risks, allowing the temperature control triggering conditions to be adjusted in real time based on actual process risks. In the early stages of the reaction, when viscosity is low, the threshold is high, allowing for larger process fluctuations and preventing the control system from overreacting. As the reaction progresses and viscosity increases, the threshold decreases smoothly and rapidly, making the control system exceptionally sensitive and able to intervene promptly at the early signs of drastic temperature fluctuations.

[0058] This process can be represented as: in, It is the calculated dynamic threshold; is the preset maximum allowable temperature change rate, which can be taken as 5℃ / min in the original control strategy; k is the slope factor, which determines how steep the threshold changes with viscosity. For example, in one example, k can take a value between 0.01 and 0.1. It is the predicted viscosity of the input; while This is a critical viscosity reference point, marking the turning point where the system's thermal risk begins to increase significantly. This value needs to be determined experimentally, for example, in a specific but non-limiting implementation. It can be set to 1000 mPa·s, which corresponds to the viscosity region where the system's heat transfer efficiency begins to decrease significantly.

[0059] Finally, based on the adaptive temperature change rate threshold at the current moment, feedforward-feedback coordinated control is performed on the real-time temperature sequence of the material in the reaction pipeline and the target reaction temperature setpoint to obtain the carbon dioxide compensation pressure regulation signal and the jacket heat exchange medium temperature regulation signal. It should be understood that the dynamic threshold calculated in the previous step requires a precise execution logic to translate into actual operation of the production unit, and this forward-looking feedforward adjustment needs to be combined with traditional feedback control to ensure the stability and robustness of the system.

[0060] Specifically, within each sampling period, the control system first calculates the actual rate of change of material temperature. Then, a feedforward control decision is made: Compared with the dynamic threshold calculated in the second step The system compares the values. Once the actual rate of change reaches or exceeds this dynamic threshold, the system immediately triggers gas pressurization compensation, increasing the CO2 pressure from the first pressure value to the second pressure value. Simultaneously, an independent PID feedback control loop continuously operates, monitoring the real-time temperature. Compared with the target set value To fine-tune the temperature of the heat exchange medium in the jacket, adjust the temperature of the medium to compensate for the deviation between the two.

[0061] By implementing this feedforward-feedback coordinated control, potential and drastic temperature fluctuations can be suppressed in their infancy, ensuring that the entire polymerization process is maintained smoothly within the optimal temperature range, and eliminating various side reactions caused by local overheating.

[0062] The core control triggering logic is represented as follows: Among them, when in The actual rate of temperature change measured within the sampling time is greater than or equal to the dynamically calculated threshold. When the control trigger condition is met.

[0063] Once the above conditions are met, the system immediately executes the feedforward control command, which triggers gas pressurization compensation: CO2 gas at a second pressure value is introduced into the reaction pipeline 106 through the carbon dioxide gas inlet 102, and at the same time, CO2 at a lower temperature (e.g., 50~65℃) can be introduced to achieve rapid cooling.

[0064] Meanwhile, an independent PID feedback control loop continues to operate. This loop continuously monitors the deviation between the real-time material temperature and the target reaction temperature (e.g., 80±5℃) and fine-tunes the temperature of the heat exchange medium in the jacket 105 to maintain the macroscopic temperature stability of the reaction system.

[0065] This preferred embodiment, by introducing data-driven predictive and adaptive control, fundamentally improves the stability, safety, and product quality consistency of the one-step production process of bisphenol A-type low molecular weight polycarbonate polyether polyols. The achieved technical effects are multifaceted: First, through viscosity-predictive feedforward control, the hysteresis of traditional feedback control is effectively overcome, enabling the prediction and early intervention of drastic temperature fluctuations. This significantly reduces the risk of bisphenol A decomposition due to temperature overshoot during the reaction, thereby significantly improving the color of the final product. The value can be stably controlled at an extremely low level (not exceeding 0.1). Secondly, the more stable temperature profile and reaction environment ensure the uniformity of polymer chain growth, which further reduces and stabilizes the polydispersity index (PDI) of the product, resulting in more uniform product quality. Finally, this more intelligent and precise control strategy not only improves the safety of the production process and effectively avoids dangerous conditions such as explosive polymerization, but also provides solid technical support for the stable scale-up and large-scale industrial production of this process.

[0066] More preferably, in the above reaction process, density is taken as the reaction endpoint, and the density reaches 1.1~1.3 g / cm³. 3The change was less than 0.01 g / cm³ within 5 minutes. 3 The reaction is terminated at that time.

[0067] Furthermore, during the polymerization reaction, the circulation flow rate of the circulating pump 007 is controlled to complete one cycle in 10-15 minutes. More preferably, the circulation flow rate of the circulating pump 007 is 10 minutes to complete one cycle. By adjusting the circulation flow rate of the circulating pump 007, the heat conduction, gas-liquid mass transfer, and solid-liquid mixing processes are fully carried out in the reaction process, ensuring the stable progress of the reaction process and improving the quality of the product and production efficiency.

[0068] (6) After the reaction is completed, the reaction product is a mixture containing polycarbonate polyether polyol, cyclic carbonate, and unreacted propylene oxide. The reaction product flows out from the outlet. The discharge from the outlet at one time shall not exceed 80% of the volume of the reaction pipe 106. Then the reaction product is passed into the separation unit 008 in the post-processing step. The separation unit 008 separates the propylene oxide and dissolved CO2 in the mixture to obtain a crude product, and adjusts the viscosity of the crude product at the same time. The crude product is passed into the purification unit 009, where a refining agent is added for adsorption treatment. After filtration, a crude product with a catalyst metal content of less than 10 ppm is obtained. The purified crude product is passed into the distillation unit 010 to separate the main product, polycarbonate polyether polyol, and the by-product, cyclic carbonate, to obtain the polycarbonate polyether polyol product, which is then filled.

[0069] It should be noted that the aforementioned premixing unit 005, separation unit 008, purification unit 009, distillation unit 010, etc., can all refer to the existing structure, and will not be described in detail here.

[0070] The features and performance of the present invention will be further described in detail below with reference to embodiments.

[0071] Example 1 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, using the integrated reaction device mentioned above, and the reaction process is as follows: 8L of propylene oxide, 4g of DMC catalyst, and 520g of bisphenol A were added to a premixing reactor. After introducing carbon dioxide at 0.4MPa, the mixture was stirred at 40℃ for 1 hour. The mixture was then forced into an 8L×2 integrated tubular reactor, with each reaction pipe having a diameter of 100mm and a length of 1000mm. After complete insertion, carbon dioxide was introduced into the reaction pipes to a pressure of 3MPa and maintained at this pressure. The circulation pump was started, and the temperature was raised to 80℃ for polymerization. One cycle was completed every 10 minutes (the circulation pump flow rate was approximately 600g / min). During the heating process, the temperature difference between the heat exchange medium in the jacket and the temperature inside the reaction pipes was controlled at 3℃, slowly increasing the temperature of the material inside the reaction pipes until the raw material temperature reached 80℃, initiating the polymerization reaction.

[0072] During the polymerization reaction, temperature is monitored, and the following steps are performed: (1) When the temperature of the temperature sensor in the middle of the reaction pipeline (i.e. the material temperature) is higher than 80°C, the temperature of the heat exchange medium in the jacket is reduced. The temperature reduction of the heat exchange medium is equal to the difference between the temperature sensor and the temperature being higher than 80°C, so that the material temperature is kept in balance at 80°C.

[0073] (2) When the temperature of the material in the reaction pipeline is detected to rise above 85°C, the CO2 purification system introduces CO2 gas into the carbon dioxide replenishment port at a temperature of 60°C, replenishes the CO2 pressure to 4MPa, and lowers the temperature of the heat exchange medium in the jacket. The temperature reduction of the heat exchange medium is the difference between the material temperature and 80°C, until the material temperature drops to 80°C.

[0074] After 3 hours of reaction, the density uniformly increased to 1.12 g / cm³. 3 And it is stable (change within 5 minutes is less than 0.01 g / cm³). 3 At this point, the reaction ends, and the temperature is lowered to remove the product. After removing the catalyst using a catalyst filtration device, a scraped evaporator is used to separate the main and by-products.

[0075] The aforementioned DMC catalyst is a zinc-cobalt bimetallic cyanide complex catalyst obtained by reacting water-soluble metal salts of zinc and cobalt in an aqueous solvent. The specific preparation method is as follows: Potassium hexacyanocobalaminate and zinc bromide are weighed in a molar ratio of 1:4, dissolved in an aqueous solvent containing water and tert-butanol, and stirred continuously. The total mass ratio of the metal salts (i.e., cobalt salt and zinc salt) to the aqueous solvent is 1:5. An inorganic acid and an organic acid are added. The inorganic acid is dilute hydrochloric acid with a pH of 2, and the organic acid is glutaric acid. The molar ratio of the inorganic acid to the organic acid is 5:1, and the ratio of the total molar number of metal salts to the molar number of acids is 4:1. The mixture is stirred at 10-100℃ for several hours, and a precipitate continues to form. The precipitate is then filtered and dried to obtain a filter cake. The filter cake is re-slurryed and washed with an aqueous solvent at a temperature of 10-100℃. Specifically, the washing temperature is 100℃, the washing time is 3 minutes, and after stirring for several hours, the filter cake is dried by vacuum filtration. The above slurrying, washing, and drying steps are repeated multiple times at a temperature of 10-100℃ until the pH of the liquid system is 6-7. Specifically, the temperature is 60℃, and the drying time is 6 minutes each time. The filter cake is further dried under vacuum at 80-100℃ to obtain the final catalyst. Before use, the catalyst is processed into powder particles by mechanical grinding under anhydrous drying conditions.

[0076] The purified products were sampled and analyzed. Specifically, the polymerization products (polycarbonate-polyether polyol, cyclic propylene carbonate, and unreacted propylene oxide) were collected in a container. The polymerization product samples were characterized by 1H NMR spectroscopy to calculate the ratio of polymer to cyclic small molecules in the crude product. The polymer was purified and then subjected to 1H NMR spectroscopy to calculate the ratio of polycarbonate segments to polyether segments on the polymer backbone. The polymer backbone has only two structures, polycarbonate segments and polyether segments, and the sum of their percentages is 100%.

[0077] With the help of 1 The amount of carbon dioxide introduced into the polycarbonate polyether polyol (carbonate repeatr content) and the ratio of propylene carbonate (cyclic carbonate) to polycarbonate polyether polyol were determined by ¹H-NMR (Bruker, DPX400, 400 MHz; pulse program zg30, waiting time d1:10 s, 64 scans). In all cases, the sample was dissolved in deuterated chloroform. 1 The relevant resonance proton peaks in H-NMR (based on TMS=0ppm) are as follows: Among them, 5.0 ppm and 4.2 ppm belong to the proton peaks on the methylene and methine groups of polycarbonate chains, 4.9 ppm, 4.5 ppm and 4.1 ppm belong to the proton peaks on the methylene and methine groups of five-membered ring carbonates, and 3.5-3.8 ppm belong to the proton peaks of ether chains. The integrated area of ​​the peak at a certain ppm on the 1H NMR spectrum is represented by the capital letter A followed by a numerical subscript, for example, A... 5.0This represents the integrated area of ​​the peak at 5.0 ppm. Based on the crude copolymer product... 1 Calculate the integral area of ​​the H-NMR spectrum and its associated proton peaks, and calculate the proportion (molar ratio) of carbonate repeating units F in the copolymerization reaction. CO2 and cyclic carbonate content (mass fraction W) PC Carbon dioxide insertion amount M CO2 The specific calculation method is as follows: 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 +A1.5)+58×A 3.5 ×100%; M CO2 =44×F CO2 / [102×F CO2 +58×(1-F CO2 )]×100%.

[0078] Coefficient 44 represents the molar mass of carbon dioxide, coefficient 58 represents the molar mass of PO (propylene oxide), and coefficient 102 represents the sum of the molar masses of carbon dioxide (44 g / mol) and PO (58 g / mol).

[0079] The formula for calculating the product conversion rate n is n = m × (1 - M) CO2 ) / (Mm×M CO2 ); where m is the mass of the product after removing propylene oxide, and M is the total sample mass containing propylene oxide.

[0080] The number-average molecular weight (Mn) and the polydispersity index (PDI) of the polymer were determined by gel permeation chromatography (GPC).

[0081] The hydroxyl value (OHV) is determined by GB / T 12008.3-2009 Plastics Polyether Polyols Part 3: Determination of Hydroxyl Value.

[0082] The final product was subjected to colorimetric testing. 5g of the sample was placed in a cuvette, which was then placed in a dark environment to minimize the influence of light sources on the test and reduce errors. An NR10QC colorimeter was used for testing, and the test data included three basic indicators (L). a b .

[0083] Where L The value represents the color brightness, L =0 indicates black, L =100 indicates white.

[0084] Where a The value represents the position between red / magenta and green, a A negative value indicates green, a The indicator color is red, indicating a positive value.

[0085] Where b The value represents the position between yellow and blue, b Negative values ​​indicate blue, b A positive value indicates yellow.

[0086] a value, b The smaller the absolute value, the better; the smaller the value, the closer it is to colorless.

[0087] The test results are shown in Table 1 below: Table 1 As can be seen from Table 1, the production process provided in this embodiment of the invention can fully react the raw materials at 80°C, resulting in a narrower molecular weight distribution of the prepared polycarbonate polyether polyol, with a distribution around 1.1; b The value is less than 0.1, close to 0, indicating that the product did not turn yellow; the proportion of carbonate segments is higher, above 55%, indicating a high carbon dioxide fixation rate. Furthermore, the reaction time is very short, requiring only 3 hours to reach the predetermined conversion rate, resulting in relatively lower energy consumption.

[0088] Example 2 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, using the same production process as in Example 1, but differing from Example 1 in the following aspects: The raw materials added were: 32L propylene oxide, 16g DMC catalyst, and 2080g bisphenol A, using an 8L×8 integrated tubular reactor. The circulation flow rate was controlled to complete one cycle in 10 minutes (the circulation pump flow rate was approximately 2400g / min).

[0089] Example 3 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, using the same production process as in Example 1, but differing from Example 1 in the following aspects: The raw materials added were: 300L propylene oxide, 150g DMC catalyst, and 19500g bisphenol A, using a 240L×2 integrated tubular reactor. The reaction pipeline had a diameter of 220mm and a length of 8600mm. When the liquid content in the reaction pipeline was >10%, the circulation pump was turned on, and the circulation flow rate was controlled to complete one cycle in 10 minutes (the circulation pump flow rate was approximately 22500g / min).

[0090] Example 4 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, using the same production process as in Example 1, but differing from Example 1 in the following aspects: The gas-liquid volume ratio is 1:4.

[0091] Example 5 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, using the same production process as in Example 1, but differing from Example 1 in the following aspects: The length-to-diameter ratio of the reaction pipe is 40:1.

[0092] Example 6 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, using the same production process as in Example 1, but differing from Example 1 in the following aspects: The reaction temperature is 70℃.

[0093] Example 7 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, using the same production process as in Example 1, but differing from Example 1 in the following aspects: The reaction temperature is 85℃.

[0094] Example 8 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, using the same production process as in Example 1, but differing from Example 1 in the following aspects: The circulation rate is controlled to complete one cycle in 15 minutes (the circulation pump flow rate is approximately 900 g / min).

[0095] Example 9 This embodiment provides a production process for bisphenol A type low molecular weight polycarbonate polyether polyol. The raw material formulation, reaction device, premixing and heating process parameters are basically the same as those in Example 1.

[0096] The key difference between it and Example 1 is that in step (5) of the polymerization reaction process, the gas pressurization compensation triggering mechanism adopts the feedforward-feedback collaborative adaptive control method based on viscosity prediction described above.

[0097] The specific operation is as follows: During the polymerization reaction, the control system collects data such as material temperature, pressure, density, and circulating pump flow rate in the reaction pipeline in real time, and calculates the predicted viscosity of the material at future moments using a dynamic viscosity prediction model. Then, the adaptive temperature change rate threshold at the current moment is calculated based on the Sigmoid function. .

[0098] The core triggering logic of the control system is: when the real-time monitored material temperature change rate... Greater than or equal to the dynamically calculated threshold In such cases, gas pressurization compensation is immediately initiated. For example, in the later stages of the reaction, when the predicted increase in viscosity causes the dynamic threshold to decrease from the initial 5℃ / min to 1.5℃ / min, once the system detects that the temperature change rate reaches 1.5℃ / min, the compensation mechanism is immediately triggered, increasing the CO2 pressure from 3MPa to 4MPa and introducing 60℃ CO2 gas for rapid cooling and mass transfer enhancement until the temperature returns to stability. Throughout the entire process, the jacket temperature is continuously and collaboratively regulated by a PID feedback control loop.

[0099] The reaction was terminated after 3 hours when the density reached 1.12 g / cm³ and stabilized (with a change of less than 0.01 g / cm³ within 5 minutes). The product was then tested.

[0100] The products obtained in Examples 2-9 were tested according to the method in Example 1, and the test results are shown in Table 2 below.

[0101] Table 2 Compared to Example 1, Examples 2 and 3 were scaled up in production at different ratios. As shown in Table 2, the molecular weight, molecular weight distribution, and conversion rate of the polymers obtained in Examples 2 and 3 did not show significant fluctuations. Compared to Example 1, Examples 4-8 made certain adjustments to the gas-liquid ratio, reaction temperature, and liquid circulation speed. Within a certain range, changing a single condition did not cause significant fluctuations in the molecular weight, molecular weight distribution, and conversion rate of the polymer. The integrated tubular reactor provided in this invention does not affect the molecular weight, molecular weight distribution, and conversion rate of the polymer after scaling up, exhibiting no significant scale-up effect. Furthermore, during the scale-up process, identical parallel reaction pipelines can share a single heating device, reducing energy consumption during production.

[0102] Furthermore, it is worth noting that, compared to Example 1, Example 9 employs a feedforward-feedback collaborative adaptive control method based on viscosity prediction, and the results demonstrate the significant superiority of this preferred embodiment. Compared to Example 1, which uses basic fixed threshold control, Example 9 achieves further improvements in all key indicators: its polymer molecular weight polydispersity index (PDI) further decreases from 1.13 to 1.08, indicating a more uniform molecular weight distribution; color b The value decreased from 0.04 to 0.02, indicating that the product has a better color and is almost colorless and transparent.

[0103] Comparative Example 1 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, with the production process described in Example 1. The difference between this and Example 1 is that: The CO2 pressure was always 3 MPa, and no CO2 pressurization compensation was performed when the temperature rose sharply.

[0104] Comparative Example 2 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, with the production process described in Example 1. The difference between this and Example 1 is that: During the heating process, the temperature of the heat exchange medium in the jacket 105 of the reaction pipeline is controlled at 80°C until the reaction temperature in the reaction pipeline is raised to 80°C.

[0105] Comparative Example 3 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, which differs from the one in Example 1 in that: The liquid circulation rate in the reaction unit was 25 min to complete one cycle, and the remaining reaction conditions were the same as in Example 1.

[0106] Comparative Example 4 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, which differs from the one in Example 1 in that: After the heating is completed, the polymerization reaction is carried out. Temperature monitoring is not performed during the polymerization reaction. The temperature of the heat exchange medium in the jacket is always maintained at 80℃.

[0107] Comparative Example 5 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, which differs from the one in Example 1 in that: The gas-liquid volume ratio in the reaction pipeline is 1:5, which means that the reaction raw materials are increased, and the other reaction conditions are the same as in Example 1.

[0108] Comparative Example 6 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol. The reaction apparatus differs from that of Example 1 in that the reaction pipeline does not have a dispersion plate and a gas-liquid mixing heat conduction zone, and the liquid circulation pump in the reaction unit is replaced by a gas booster pump. The reaction process is as follows: 8 L of propylene oxide, 4 g of DMC catalyst, and 520 g of bisphenol A were added to a premixing reactor. Carbon dioxide was introduced at 0.4 MPa, and the mixture was stirred at 40°C for 1 hour. The mixture was then forced into an 8 L × 2 reactor array, with each reaction pipe having a diameter of 100 mm and a length of 1000 mm. After complete insertion, carbon dioxide was introduced into the reaction pipes to a pressure of 3 MPa and maintained at this pressure. A booster pump was used to compress the carbon dioxide at the top of the pipes and introduce it from the bottom, ensuring complete dissolution of carbon dioxide in the material inside the pipes. The pressure ratio was 25:1. After reacting at 80°C for 3 hours, the density uniformly increased to 1.12 g / cm³. 3 The reaction stabilizes, at which point it ends, and the temperature is lowered to remove the product. After removing the catalyst using a catalyst filtration device, a scraped evaporator is used to separate the main and by-products.

[0109] The products obtained by Comparative Examples 1-7 were tested according to the method in Example 1, and the test results are shown in Table 3 below.

[0110] Table 3 Compared to Example 1, Comparative Example 1 directly uses a heating jacket to control the temperature of the reaction unit without supplementing low-temperature CO2. This method is prone to causing large temperature changes when the reaction is vigorous, requiring supplementation with low-temperature CO2 to stabilize the temperature of the materials in the reaction pipeline, resulting in the product turning yellow. At the same time, the rate of CO2 consumption in the liquid material increases, and without excessive CO2 supplementation, the dissolution rate of CO2 cannot keep up with the consumption rate, resulting in excessively high PDI and relatively low ester content.

[0111] Compared to Example 1, Comparative Example 2 directly heated the reaction pipe with a higher-temperature heat exchange medium without fine-tuning the heating process. This method results in uneven heating, with the material near the pipe wall heating up rapidly, causing localized rapid heat release and excessively high local temperatures. Consequently, the molecular weight distribution becomes wider, and product b... The value increases, meaning the color turns yellow.

[0112] Compared to Example 1, Comparative Example 3 reduced the liquid circulation rate. The lower circulation rate caused the temperature generated by the reacted material to accumulate, resulting in explosive polymerization and high-temperature oxidation of bisphenol A, which caused the product to turn yellow.

[0113] Compared to Example 1, Comparative Example 4 did not perform temperature control during the polymerization reaction, which caused the reactants to accumulate at high temperatures, resulting in the high-temperature oxidation of bisphenol A and causing the product to turn yellow.

[0114] Compared with Example 1, Comparative Example 5 reduced the gas-liquid ratio. The reduction in the gas-liquid ratio not only resulted in poorer mass and heat transfer efficiency in the CO2 region, leading to a decrease in ester content and a yellowing color, but also increased the heat of formation of the material during the reaction, making temperature control more difficult and making it extremely easy for the material to explode.

[0115] Compared to Example 1, Comparative Example 6 lacks a gas-liquid mixing heat conduction zone and uses gas circulation within a pipe to complete gas-liquid mass transfer. This method has a lower actual conversion rate and a wider molecular weight distribution (PDI). Since there is no liquid circulation to continuously mix the material and release heat, the reaction speed is faster, the generated heat is more difficult to release and remove in a short time, the color is yellowish, and it is more prone to explosive polymerization.

[0116] As can be seen from the above embodiments and comparative examples, the production process of bisphenol A type low molecular weight polycarbonate polyether polyol of the present invention is carried out in an integrated tubular reactor with a special structure. The material can circulate in the reaction pipeline for polymerization. With the help of a specific process control program, the obtained product has a low PDI, high carbon dioxide conversion rate, and is close to white. This effectively solves the problem of product yellowing caused by the one-step production process in the prior art. The product has a narrow molecular weight distribution, no scale-up effect, strong controllability of product molecular weight, stable production between batches, and high product quality. At the same time, the production process is safe and controllable, not prone to explosive polymerization, and has no scale-up effect, making it suitable for large-scale industrial production.

[0117] The embodiments described above are some, but not all, embodiments of the present invention. The detailed description of the embodiments of the present invention is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

Claims

1. A production process for bisphenol A type low molecular weight polycarbonate polyether polyol, characterized in that, The production process is carried out in an integrated tubular reactor having at least one reaction channel, and includes: A premixture is introduced into the reaction pipeline in one step, and CO2 at a first pressure is introduced; wherein the premixture is obtained by premixing the total amount of epoxy compound, bisphenol A and catalyst by introducing CO2. The premixture is heated and circulated within a reaction vessel to carry out a polymerization reaction, followed by separation to obtain a bisphenol A type low molecular weight polycarbonate polyether polyol. During the polymerization reaction, slow temperature control and gas pressure compensation are implemented to ensure that the molecular weight polydispersity index (PDI) of the bisphenol A type low molecular weight polycarbonate polyether polyol does not exceed 1.5, and that the polydispersity index (PDI) of the polyphenol A type low molecular weight polycarbonate polyether polyol is within a certain range. a b In the color system, b The value does not exceed 0.1; The slow heating control includes: controlling the temperature difference between the heating temperature of the reaction pipe and the temperature of the material inside the reaction pipe to not exceed 3~5℃, so that the material inside the reaction pipe is heated to 75~85℃ before the polymerization reaction is carried out; the gas pressure compensation includes: during the polymerization reaction, when the temperature of the material inside the reaction pipe rises sharply, CO2 gas with a second pressure value is introduced into the reaction pipe until the temperature of the material inside the reaction pipe drops to 75~85℃, wherein the criteria for judging the sharp rise in material temperature is a temperature rise of not less than 5℃ within 1 minute, and the second pressure value is greater than the first pressure value.

2. The production process of bisphenol A type low molecular weight polycarbonate polyether polyol according to claim 1, characterized in that, When performing gas pressurization compensation, the temperature of the CO2 gas is controlled at 50~65℃.

3. The production process of bisphenol A type low molecular weight polycarbonate polyether polyol according to claim 1, characterized in that, A heat exchange medium circulates outside the reaction pipe to control the temperature of the material. During the polymerization reaction, the process also includes controlling the temperature drop of the heat exchange medium to be approximately equal to the temperature rise of the material in the reaction pipe, so that the temperature of the material in the reaction pipe is maintained at 75~85℃.

4. The production process of bisphenol A type low molecular weight polycarbonate polyether polyol according to claim 1, characterized in that, The first pressure value is 2~6MPa, and the second pressure value is 4~8MPa.

5. The production process of bisphenol A type low molecular weight polycarbonate polyether polyol according to claim 1, characterized in that, The integrated tubular reaction device includes a premixing unit and a reaction unit. The premixed mixture is obtained by premixing in the premixing unit. The reaction unit includes a circulating pump and multiple reaction pipelines. The circulating pump is used to circulate the material within the multiple reaction pipelines. The circulation flow rate of the circulating pump is 10-15 minutes to complete one cycle; or, the circulation flow rate of the circulating pump is 10 minutes to complete one cycle.

6. The production process of bisphenol A type low molecular weight polycarbonate polyether polyol according to claim 5, characterized in that, Multiple reaction pipes are connected in parallel. The inlet of each reaction pipe is connected to a liquid distributor via a connecting pipe, and the outlet is connected to the circulation pump via a connecting pipe. One end of the liquid distributor is provided with an inlet connected to the premixing unit, and the other end is connected to the circulation pump. Each reaction pipe is provided with a gas injection port for CO2 to enter. The mixed products flowing out of multiple reaction pipes converge at the circulation pump, are pumped into the liquid distributor by the circulation pump, dispersed into multiple reaction pipes, and then reach the outlet through the reaction pipes to complete one cycle.

7. The production process of bisphenol A type low molecular weight polycarbonate polyether polyol according to claim 5, characterized in that, During the polymerization reaction, the gas-liquid volume ratio in the reaction pipeline is controlled to be 1:1~4.

8. The production process of bisphenol A type low molecular weight polycarbonate polyether polyol according to claim 5, characterized in that, During the mixing process in the premixing unit, the temperature of the premixing unit is controlled at 0~40℃, the pressure at 0.1~2MPa, and the premixing time at 1~2h; when the premixed product from the premixing unit is added to the reaction unit, the temperature of the reaction pipeline is controlled at 35~45℃; the reaction product density reaches 1.1~1.3 g / cm³. 3 And the change was less than 0.01 g / cm within 5 minutes. 3 The reaction is terminated at that time.

9. The production process of bisphenol A type low molecular weight polycarbonate polyether polyol according to claim 1, characterized in that, The catalyst, excluding impurities, contains only zinc and cobalt; it is obtained by reacting water-soluble metal salts of zinc and cobalt in a water-soluble solvent, wherein the water-soluble metal salt of cobalt is a cobalt cyanide salt; the catalyst is modified with a mixed acid during synthesis, the 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 between 0 and 5; The organic acid is selected from any one or more of succinic acid, glutaric acid, phthalic acid, iminodiacetic acid, pyromellitic acid, and butanetetracarboxylic acid, and the molar ratio of the water-soluble inorganic acid to the organic acid is 1:10 to 10:

1.

10. A bisphenol A type low molecular weight polycarbonate polyether polyol prepared by the production process according to any one of claims 1 to 9, characterized in that, The structural formula of the bisphenol A type low molecular weight polycarbonate polyether polyol is represented by formula (1): Equation (1); In formula (1), R1 and R2 are selected from formula (2) or OH. Equation (2); In equation (2), 1≤n≤22, 1≤m≤39, and * indicates the connection position; The bisphenol A type low molecular weight polycarbonate polyether polyol has a number average molecular weight of 1000~3000 g / mol, a molecular weight polydispersity index (PDI) ≤ 1.5, a hydroxyl value of 35~110 mgKOH / g, and a carbonate repeating ratio F CO2 ≥45%.

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