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 larger than 55%, and in the L * a * b * 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] The invention relates to the technical field of chemistry and chemical engineering, and in particular to a bisphenol A type low molecular weight polycarbonate polyether polyol and a production process thereof. Background Art

[0002] Bisphenol A type low molecular weight polycarbonate polyether polyol is a polycarbonate polyether polyol with a molecular weight of less than 3000, which is mainly synthesized by small molecule initiator, carbon dioxide and epoxy compound through bimetallic complex catalyst. Taking propylene oxide as an example, CO2 and propylene oxide are synthesized under the action of small molecule initiator and DMC catalyst to synthesize the main product: polycarbonate polyether polyol and by-product carbonate acrylate. The synthesis route is as follows:

[0003] Using bisphenol A as an initiator, bisphenol A type polycarbonate polyether polyol can be obtained. The aromatic ring and carbon-oxygen chain structure in the molecule give the material specific rigidity and toughness respectively, thereby effectively improving the structure and properties of the polymer, giving downstream products better mechanical properties and thermal stability, and playing an important role in adhesives, rubbers, surfactants and other fields.

[0004] Prior art CN115785435A discloses a one-step method for preparing polyether polyols. The one-step method is specifically as follows: at room temperature, epoxy compounds, initiators and catalysts are added to a reaction device at one time for polymerization reaction, and no reaction raw materials are added during the reaction process, thereby significantly improving the reaction efficiency.

[0005] When the inventor used bisphenol A as an initiator and prepared bisphenol A type polycarbonate polyether polyol by a one-step method, he found that the obtained product turned yellow seriously. The reason may be that when the product is prepared by a one-step method, since all the raw materials are put into the product at one time, the temperature is likely to rise sharply in a short time during the polymerization process (for example, the temperature rises by 5°C within 1 minute). When bisphenol A is exposed to high temperature for a long time, it is easy to thermally decompose, for example, it is decomposed into several small molecules according to the position of the dotted line in the following formula: ; The decomposition products of bisphenol A easily react with the intermediate products and by-products of the polymerization reaction to form yellow substances, such as the small molecule substance dimethyl phthalate or a quinone structure with a chromophoric group, which causes the product to turn yellow and affects the downstream application of the product. Summary of the invention

[0006] The purpose of the present invention is to provide a bisphenol A type low molecular weight polycarbonate polyether polyol and a production process thereof, which is suitable for industrial large-scale production of bisphenol A type low molecular weight polycarbonate polyether polyol, can solve the problem of product yellowing caused in a one-step production process, effectively improve the overall conversion rate and safety, and reduce production costs.

[0007] According to a first aspect of the present invention, a production process of bisphenol A type low molecular weight polycarbonate polyether polyol is provided, which is carried out in an integrated tube-in-tube reaction device having at least one reaction pipeline, and the production process comprises: Introducing a premixture into the reaction pipe at one time, and introducing CO2 of a first pressure value; wherein the premixture is obtained by introducing CO2 into all the epoxy compound, bisphenol A and catalyst for premixing; The premix is ​​heated and circulated in a reaction pipe to perform a polymerization reaction, and then separated to obtain a bisphenol A type low molecular weight polycarbonate polyether polyol; wherein, during the polymerization reaction, slow temperature rise control and gas pressure compensation are performed so that the molecular weight polydispersity index (PDI) of the bisphenol A type low molecular weight polycarbonate polyether polyol does not exceed 1.5, and the carbonate segment ratio F CO2 Greater than 55%, and in the L*a*b* color system, the b* value does not exceed 0.1.

[0008] Specifically, the polydispersity index PDI is measured by gel permeation chromatography (GPC). The smaller the PDI value, the narrower the molecular weight distribution and the more uniform the product quality. More preferably, under the coordinated 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.

[0009] Specifically, the value of the L*a*b* color system can be obtained by a colorimeter. In the L*a*b* color system, the coordinate L* represents the color brightness, L*=0 indicates black, and L*=100 indicates white. The coordinate a* represents the position between red / magenta and green, a* is a negative value indicating green, and a* is a positive value indicating magenta. The coordinate b* represents the position between yellow and blue, b* is a negative value indicating blue, and b* is a positive value indicating yellow. The larger the b* value, the more serious the yellowing of the sample. Further, the product obtained by the embodiment of the present invention has an a* value of less than 0.1, and a b* value of less than 0.1, and the product is close to colorless.

[0010] In an embodiment of the present invention, the slow temperature rise control includes: controlling the difference between the heating temperature of the reaction pipe and the temperature of the material in the reaction pipe to not exceed 3-5°C, so that the material in the reaction pipe is heated to 75-85°C before performing a polymerization reaction.

[0011] In an embodiment of the present invention, gas pressurization compensation includes: during the polymerization reaction, when the material temperature in the reaction pipe rises sharply, CO2 gas of a second pressure value is introduced into the reaction pipe until the material temperature in the reaction pipe drops to 75~85°C, wherein the judgment indicator for the sharp rise in material temperature is that the temperature rises by not less than 5°C within 1 minute, and the second pressure value is 4~8MPa, which is greater than the first pressure value.

[0012] 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.

[0013] In an exemplary embodiment 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. For another example, in another embodiment, the first pressure value is 5 MPa, and the second pressure value is 7 MPa.

[0014] In an exemplary embodiment of the present invention, a heat exchange medium circulates on the outside of the reaction pipe to control the temperature of the material; during the polymerization reaction, it also includes: controlling the lowered temperature of the heat exchange medium to be roughly equal to the increased temperature of the material in the reaction pipe, so that the temperature of the material in the reaction pipe is maintained at 75~85°C.

[0015] In an exemplary embodiment of the present invention, the integrated tube-in-tube reaction device comprises a premixing unit and a reaction unit, wherein the premixing unit is premixed to obtain the premixing unit; the reaction unit comprises a circulation pump and a plurality of the reaction pipes, wherein the circulation pump is used to circulate the material in the plurality of the reaction pipes, and the circulation flow rate of the circulation pump is 10 to 15 minutes to complete one cycle. Alternatively, the circulation flow rate of the circulation pump is 10 minutes to complete one cycle.

[0016] In an exemplary embodiment of the present invention, a plurality of the reaction pipes are arranged in parallel, the feed end of each of the reaction pipes intersects with a liquid distributor through a connecting pipe, and the discharge end converges to the circulation pump through 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, and each of the reaction pipes is provided with a gas inlet for CO2 to enter; the mixed products flowing out of the plurality of reaction pipes converge together at the circulation pump, are pumped into the liquid distributor by the circulation pump, are dispersed into the plurality of reaction pipes, and then pass through the reaction pipes to reach the discharge end, completing a cycle.

[0017] In an exemplary embodiment of the present invention, during the polymerization reaction, the gas-liquid volume ratio in the reaction pipe is controlled to be 1:1-4.

[0018] In an exemplary embodiment of the present invention, during the mixing process of the premixing unit, the temperature of the premixing unit is controlled to be 0-40°C, the pressure is 0.1-2MPa, and the premixing time is 1-2h; when the material of the premixing unit is put into the reaction unit, the temperature of the reaction pipe is controlled to be 35-45°C; when the density of the reaction product reaches 1.1-1.3 g / cm 3 , and the change is less than 0.01g / cm within 5min 3 The reaction is terminated.

[0019] In an exemplary embodiment of the present invention, the metal elements of the catalyst are only two metal elements, zinc and cobalt, except for impurities; the catalyst is obtained by reacting water-soluble metal salts of zinc and cobalt in a water-soluble solvent, and the water-soluble metal salt of cobalt is a cyanide salt of cobalt; the catalyst is modified by a mixed acid during synthesis, and 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.

[0020] According to a second aspect of the present invention, there is provided a bisphenol A type low molecular weight polycarbonate polyether polyol prepared according to any one of the production processes described above, wherein the structural formula of the bisphenol A type low molecular weight polycarbonate polyether polyol is represented by formula (1): Formula (1); Wherein, in formula (1), R1 and R2 are selected from formula (2) or OH, Formula (2); Wherein, in formula (2), 1≤n≤22, 1≤m≤39, * represents 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 chain segment ratio F CO2 ≥45%.

[0021] Specifically, the carbonate chain ratio F CO2 With the help of 1 H-NMR was used to determine the product 1 The integral area of ​​the H-NMR spectrum and its related proton peaks is used to calculate the carbonate chain ratio (molar ratio) F in the copolymerization reaction. CO2 , the specific calculation method is: F CO2 =(A5.0 +A 4.2 -2×A 4.6 ) / [(A 5.0 +A 4.2 -2×A 4.6 )+A 3.5 ]×100%; among which, A 5.0 represents the integrated area of ​​the peak at 5.0 ppm, A 4.2 represents the integrated area of ​​the peak at 4.2 ppm; A 4.6 represents the integrated area of ​​the peak at 4.6 ppm, and A 3.5 It represents the integrated area of ​​the peak at 3.5ppm; 5.0ppm and 4.2ppm belong to the integrated area of ​​the proton peaks on the methine and methylene on the polycarbonate chain segment; 4.9ppm, 4.6ppm, 4.5ppm and 4.1ppm belong to the proton peaks on the methine and methylene in the five-membered ring carbonate, and 3.5-3.8ppm belongs to the proton peak of the ether chain segment.

[0022] The beneficial effects of the bisphenol A type low molecular weight polycarbonate polyether polyol and its production process according to the embodiment of the present invention are: (1) Compared with the conventional process, the embodiment of the present invention effectively shortens the reaction time and improves the production efficiency by adding the reaction raw materials in a one-step process. In addition, the temperature rise introduced in the process of preparing the product by the one-step process causes the decomposition of bisphenol A and causes the product to turn yellow. The invention solves the problem that the temperature rises sharply due to the one-step process, causing the decomposition of bisphenol A and causing the product to turn yellow. Specifically, during the heating process, the temperature-sensitive bisphenol A is protected to avoid decomposition and affect the polymerization reaction. When the reaction temperature rises sharply, carbon dioxide gas with a higher pressure value is added in time. The polymerization reaction process is controlled in a coordinated manner by the above two aspects, thereby effectively avoiding the yellowing of the product caused by reaction explosion and temperature runaway. The PDI of the obtained polyol product does not exceed 1.5, and the b* value does not exceed 0.1. The product is nearly colorless, which effectively improves the product quality and fills the technical gap of the one-step synthesis of bisphenol A type polycarbonate polyether polyol.

[0023] (2) The production process of the present invention is carried out in an integrated tube-in-tube reaction device, and the materials are continuously circulated. By designing the specific structure and parameters of the premixing unit and the reaction unit, it is ensured that the polymerization reaction process achieves sufficient gas-liquid heat conduction and gas-liquid-solid mixing. The reaction control parameters (temperature control, circulation speed control and gas compensation control) are coordinated to ensure that the molecular weight distribution of the obtained product is narrow and there is no amplification effect. The product molecular weight is highly controllable, the production is stable between batches, and the product quality is high. At the same time, the production process is safe, does not produce explosion and amplification effect, and is suitable for industrial large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings herein are incorporated into the specification and constitute a part of the specification, illustrate embodiments consistent with the present disclosure, and together with the specification are used to explain the principles of the present disclosure. Obviously, the accompanying drawings described below are only some embodiments of the present disclosure, and for ordinary technicians in this field, other accompanying drawings can be obtained based on these accompanying drawings without creative work.

[0025] Figure 1 An overall schematic diagram of an integrated tubular reaction device for producing bisphenol A type low molecular weight polycarbonate polyether polyol provided in an embodiment of the present invention, wherein the black arrow is the raw material flow direction, the green arrow is the gas entry direction, the blue arrow is the circulation direction in the pipeline reactor, and the red arrow is the product flow direction.

[0026] Figure 2 for Figure 1 Schematic diagram of the structure of the reaction unit of the reaction device. The green part represents the gas-liquid mixing heat conduction zone, and the red part represents the solid-liquid mixing zone.

[0027] Icons: 001-propylene oxide; 002-catalyst; 003-small molecule initiator; 004-CO2 gas supply device; 005-premixing unit; 006-reaction unit; 007-circulation pump; 008-separation unit; 009-refining unit; 010-distillation unit; 101-liquid distributor; 102-carbon dioxide gas supply port; 103-dispersion sheet; 104-static mixer; 105-jacket; 106-reaction pipeline. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0029] The following is a detailed description of the bisphenol A type low molecular weight polycarbonate polyether polyol and its production process according to the embodiment of the present invention. The embodiment of the present invention provides a production process of a bisphenol A type low molecular weight polycarbonate polyether polyol. Specifically, the bisphenol A type low molecular weight polycarbonate polyether polyol is synthesized by using bisphenol A as a small molecule initiator, propylene oxide and CO2 under the action of a DMC catalyst.

[0030] In the embodiment of the present invention, the structural formula of bisphenol A type low molecular weight polycarbonate polyether polyol is represented by formula (1): Formula (1); Wherein, in formula (1), R1 and R2 are selected from formula (2) or OH, Formula (2); Wherein, in formula (2), 1≤n≤22, 1≤m≤39, * represents the connection position; The number average molecular weight of the bisphenol A type low molecular weight polycarbonate polyether polyol is less than 3,000.

[0031] 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 tube reactor, see Figure 1 The integrated reaction device includes a premixing unit 005, a reaction unit 006 and a post-processing area.

[0032] It should be noted that the one-step synthesis of bisphenol A type polycarbonate polyether polyol means that all the epoxy compounds, bisphenol A and catalyst are put into the reaction device at one time, and no raw materials are added in the subsequent reaction process except for the introduction of CO2. Among them, the epoxy compound is selected from one or more of ethylene oxide, propylene oxide, 2-butylene oxide, 1,4-butylene oxide and epichlorohydrin. Preferably, in this embodiment, the epoxy compound is selected from propylene oxide.

[0033] Furthermore, the DMC catalyst used in this embodiment is a mixed acid modified zinc-cobalt double metal cyanide catalyst, the metal elements of the catalyst are only two metal elements, zinc and cobalt, except for impurities; the catalyst is obtained by reacting water-soluble metal salts of zinc and cobalt in a water-soluble solvent, and the water-soluble metal salt of cobalt is a cyanide salt of cobalt; the catalyst is modified by a mixed acid during synthesis, and 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.

[0034] See also Figure 1 and Figure 2 The premixing unit is provided with a premixing device, which can be, for example, a premixing kettle, and the raw materials are put into the premixing unit for premixing. The premixed raw materials are passed into the reaction unit 006, and after the reaction is completed, the reaction product is passed into the next step for post-treatment.

[0035] Specifically, in a preferred embodiment, the reaction unit 006 includes a reaction pipe 106, a liquid distributor 101, a circulation pump 007, a carbon dioxide gas replenishment port 102, a dispersion sheet 103 and a jacket 105. There are multiple reaction pipes 106, and multiple reaction pipes 106 are arranged in parallel. A jacket 105 is provided on the outside of each reaction pipe 106, and a heat exchange medium such as steam, water, and heat transfer oil is introduced into the jacket 105 to control the temperature of the reaction pipe 106. The space between the multiple reaction pipes 106 is filled with a heat exchange medium, and an insulation layer is provided on the outside of the heat exchange medium. The feed ends of the multiple reaction pipes 106 intersect at the liquid distributor 101 through a connecting pipe, and the discharge ends converge at the circulation pump 007 through a connecting pipe. The reaction mixture product flowing out from the discharge end of the reaction pipe 106 enters from the feed end of the reaction pipe 106 via the circulation pump 007, passes through the reaction pipe 106 to reach the discharge end, and completes a cycle.

[0036] Specifically, each reaction pipeline 106 is provided with a carbon dioxide inlet 102 for CO2 to enter. Each reaction pipeline 106 has the same material circulation path formed by the connecting pipeline and the circulation pump 007.

[0037] Further preferably, the number of reaction pipes 106 is 2 to 8, for example, 4, 6, etc. The multiple reaction pipes 106 are independent of each other and are each provided with independently controllable valves. By independently controlling each reaction pipe 106, when the temperature of a certain reaction pipe 106 is too high or other undesirable conditions occur, it can be controlled separately in time to avoid affecting the entire reaction process.

[0038] Further preferably, the center distance between two adjacent reaction pipes 106 is less than or equal to 2 times the inner diameter of the reaction pipe 106. Further preferably, the aspect ratio of the reaction pipe 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 aspect ratio of the reaction pipe is too large, it is not conducive to breaking up the reaction heat generated, which easily leads to the decomposition of the polyester chain segments and the yellowing of the product. If the aspect ratio of the reaction pipe is too small, the center position is too far from the pipe wall position, which will form a large temperature difference, resulting in a widening of the molecular weight distribution. At the same time, the reaction process continues to generate heat, which will increase the temperature of the reaction system. The reactor needs to release the heat generated in the material in time. When the flow rate is constant, the liquid needs to complete the circulation within the specified time to release heat and gas-liquid mass transfer. Through the length and center distance of the reaction pipe 106, it is ensured that the reaction process has sufficient heating reaction time and meets the requirements of production efficiency.

[0039] For further details, please refer to Figure 2 As shown, the reaction pipeline 106 includes a dispersion sheet 103, a gas-liquid mixing heat conduction zone ( Figure 2The green part in the figure) and the solid-liquid mixing area ( Figure 2 The red part in the figure). The dispersion sheet 103 is used to disperse and control the material in the gas-liquid mixing heat conduction zone to be dispersed into liquid beads for mass transfer and heat transfer without contacting the pipe wall. The solid-liquid mixing zone is used to achieve 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 dispersion sheet 103, it flows from the gas-liquid mixing heat conduction zone to the solid-liquid mixing zone, and then circulates to the dispersion sheet 103 through the 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 part extending to the gas-liquid mixing heat conduction zone. The dispersion sheet 103, the gas-liquid mixing heat conduction zone and the static mixer part in the zone, the reaction pipe 106 and the loop between the circulation pump 007 together constitute a gas-liquid mixing heat conduction path, so that the mixed material with a low CO2 content in the reaction unit dissolves CO2 again, and heat exchange is performed in the gas-liquid mixing heat conduction zone. The loops between the static mixer 104, the reaction pipe 106 and the circulation pump 007 together constitute a solid-liquid mixing path, so that the solid catalyst is evenly dispersed in the epoxy compound, while dispersing the generated reaction heat, reducing the temperature difference between the center temperature in the reaction pipe and the pipe wall, and avoiding the generation of explosion points.

[0040] Further preferably, the length of the gas-liquid mixed heat transfer zone accounts for 20% to 50% of the length of the reaction pipe to ensure sufficient gas-liquid mass transfer efficiency.

[0041] Further preferably, during the polymerization reaction, the gas-liquid volume ratio in the reaction pipe 106 is controlled to be 1:1 to 4. For example, the gas-liquid volume ratio of the reaction pipe is 1:1, 1:2, 1:4, etc. 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 in the reaction pipe, the ratio of gas to liquid is ensured to be appropriate. If the gas-liquid ratio is too low, it will not only cause the mass transfer and heat transfer efficiency in the CO2 region to deteriorate, reduce the ester content and turn the color yellow, but also easily lead to an increase in the heat of formation of the material during the reaction, increase the difficulty of temperature control, and easily implode.

[0042] Further preferably, the dispersion sheet 103 is arranged at a position of 10 to 50 mm near the top of the reaction pipeline 106, and it is provided with a plurality of dispersion holes. By arranging the dispersion sheet 103, the reaction materials can be evenly dispersed, and flow down in a water drop shape at the end, increasing the mass transfer and heat transfer area. The static mixer 104 and the circulating pump 007 built in the coordinated reaction pipeline 106, the whole circulating dispersion system can replace the traditional stirring process to continuously mix the reaction materials in the circulation process. At the same time, the dispersion sheet 103 can effectively make the reaction materials carry out better gas-liquid mass transfer and release excess heat in the gas region.

[0043] Further preferably, a temperature sensor is provided inside the reaction pipe 106, and a density detector is provided at the outlet, and the jacket temperature is adjusted according to the material density and the temperature inside the reactor to control the reaction rate. Specifically, in one embodiment, temperature sensors are provided at the middle and bottom of the reaction pipe 106 to more comprehensively monitor the temperature inside the reaction pipe 106.

[0044] The production process of bisphenol A type low molecular weight polycarbonate polyether polyol provided in the embodiment of the present invention comprises the following steps: (1) At a temperature of 0-40°C, all the epoxy compounds, bisphenol A and catalysts are added to the premixing unit 005 at one time, and CO2 is introduced for mixing to obtain a premixed mixture. Specifically, propylene oxide 001 is first added to the premixing kettle, and then a certain amount of small molecule initiator 003 and DMC catalyst 002 are added to the premixing kettle, and then carbon dioxide is supplemented and introduced into the premixing kettle through the CO2 gas supply device 004. Preferably, the temperature of the premixing unit is 40°C, the carbon dioxide pressure is 0.1-2MPa, and the premixing time is 1-2h. More preferably, the premixing time is 1h.

[0045] (2) The premix is ​​fed into each reaction pipe 106 in the reaction unit at one time through the feed 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°C 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.

[0046] (3) When the raw materials have completely entered the reaction unit, the feeding is completed. Carbon dioxide is supplemented through the carbon dioxide gas supply port 102, and the pressure value of CO2 is controlled to be a first pressure value of 2 to 6 MPa. More preferably, the pressure value of CO2 is controlled to be 3 MPa. When the pressure is too low, a solenoid valve is used to automatically introduce carbon dioxide from the carbon dioxide gas supply port 102 to supplement the pressure.

[0047] (4) Turn on the circulation pump 007, adjust the temperature of the heat exchange medium in the jacket 105, and slowly increase the temperature to raise the temperature of the material in the reaction pipe 106 to the reaction temperature, and the reaction temperature is 80±5°C. For example, the reaction temperature is 80°C, 78°C, etc. Specifically, the slow heating process includes: controlling the temperature difference between the heat exchange medium in the jacket 105 and the temperature of the material in the reaction pipe 106 to not exceed 3~5°C. Preferably, the temperature difference between the heat exchange medium in the jacket 105 and the temperature of the reaction pipe 106 is controlled to be 3°C, and the temperature of the reaction pipe 106 is slowly increased until the temperature of the reaction pipe 106 reaches 80±5°C. More preferably, during the heating process, the temperature value of the temperature sensor installed in the middle of the reaction pipe 106 is used as the temperature of the reaction pipe 106. By slow heating control, it is possible to avoid the material temperature from being increased too quickly, causing bisphenol A to be decomposed into small molecules, which affects the polymerization reaction effect and product quality.

[0048] (5) After the temperature is raised to 80±5°C, the polymerization reaction is carried out, the circulation pump 007 is kept turned on, and the temperature in 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 reduced temperature of the medium in the jacket 105 is roughly equal to the increased or reduced temperature of the reaction pipe 106, so that the material temperature is maintained at 80±5°C. Specifically, in the above process, the temperature value measured by the temperature sensor installed at the bottom of the reaction pipe 106 is used as the temperature of the reaction pipe 106. The temperature in 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, so that the temperature of the reaction system is kept relatively constant.

[0049] At the same time, gas pressure compensation control is performed during the above-mentioned polymerization reaction process. The steps of gas pressure compensation control include: during the polymerization reaction process, when the temperature of the material in the reaction pipe 106 rises sharply, CO2 gas of a second pressure value is introduced into the reaction pipe 106 until the temperature of the material in the reaction pipe 106 drops to 80±5°C, wherein the judgment index of the sharp rise in the material temperature is that the temperature rise is not less than 5°C within 1 minute, and the second pressure value is 4~8MPa, and is greater than the first pressure value.

[0050] Specifically, when the polymerization reaction occurs more violently, or when the reaction rate in a local area is too fast, the material temperature will rise sharply. When the temperature in the reaction pipe is monitored to rise sharply, the purified CO2 gas provided by the carbon dioxide purification unit is added to the reaction pipe 106 through the carbon dioxide gas supply port 102 until the material temperature in the reaction pipe 106 is reduced to 80±5°C. Among them, the judgment index for the sharp rise in material temperature is that the temperature rise is not less than 5°C within 1min. Preferably, when the purified CO2 gas is added, the CO2 gas temperature is 50~65°C, for example, the CO2 gas temperature is 50°C, 55°C, 60°C, etc. For example, in one embodiment, the reaction temperature is 80°C, and when the material temperature in the reaction pipe rises to more than 85°C within 1min, the CO2 purified gas with a temperature of 60°C is added until the temperature in the reaction pipe is reduced to 80°C. By adding low-temperature and high-pressure CO2 gas, the material can be quickly cooled to reduce the risk of implosion. And because of the addition of higher pressure CO2 gas, the gas-liquid mass transfer degree in the pipeline is greatly increased. Through the coordinated control of this step and the aforementioned slow heating program, the occurrence of yellowing of the product can be extremely effectively avoided.

[0051] Further preferably, in the above reaction process, the density is taken as the reaction end point, and when the density reaches 1.1-1.3 g / cm 3 The change is less than 0.01g / cm2 within 5 minutes. 3 The reaction is terminated.

[0052] Furthermore, during the polymerization reaction, the circulation flow rate of the circulation pump 007 is controlled to complete one cycle in 10 to 15 minutes. More preferably, the circulation flow rate of the circulation pump 007 is 10 minutes to complete one cycle. By regulating the circulation flow rate of the circulation pump 007, it is ensured that the reaction process is fully carried out in heat conduction, gas-liquid mass transfer, solid-liquid mixing and other processes, the reaction process is ensured to be carried out stably, and the quality and production efficiency of the product are improved.

[0053] (6) After the reaction is completed, the reaction product is a mixture containing polycarbonate polyether polyol, cyclic carbonate and unreacted raw material propylene oxide. The reaction product flows out from the discharge port. The single discharge of the discharge port is not more than 80% of the volume of the reaction pipe 106. The reaction product is then passed into the separation unit 008 in the post-treatment step, and 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 refining unit 009, and a refining agent is added for adsorption treatment. After filtering, a crude product with a catalyst metal content of less than 10 ppm is obtained. The refined crude product is passed into the distillation unit 010 to separate the main product polycarbonate polyether polyol and the by-product cyclic carbonate, that is, the polycarbonate polyether polyol product is obtained, and then filled.

[0054] It should be noted that the above-mentioned premixing unit 005, separation unit 008, refining unit 009, distillation unit 010, etc. can all refer to the existing structure and will not be described in detail here.

[0055] The features and performance of the present invention are further described in detail below in conjunction with the embodiments.

[0056] Example 1 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, using the above-mentioned integrated reaction device, the reaction process is as follows: 8L propylene oxide, 4g DMC catalyst, and 520g bisphenol A were added to the premixing kettle respectively, and 0.4MPa of carbon dioxide was introduced and mixed and stirred at a temperature of 40°C. After stirring for 1h, the mixture was pressed into an 8L×2 integrated tube reactor, and the diameter of a single reaction pipe was 100mm and the length of the reaction pipe was 1000mm. After all the mixture was pressed in, carbon dioxide was introduced into the reaction pipe to 3MPa and the pressure was maintained. The circulation pump was turned on, and the temperature was raised to 80°C for polymerization reaction. During the reaction, the reaction was controlled to complete a cycle in 10min (the flow rate of the circulation pump was about 600g / min). During the heating process, the temperature difference between the heat exchange medium in the jacket and the temperature in the reaction pipe was controlled to be 3°C, and the temperature of the material in the reaction pipe was slowly raised until the temperature of the raw materials in the reaction pipe was raised to 80°C for polymerization reaction.

[0057] During the polymerization reaction, the temperature was monitored and the following steps were performed: (1) When the temperature of the temperature sensor in the middle of the reaction pipe (i.e., the material temperature) is monitored to be higher than 80°C, the temperature of the heat exchange medium in the jacket is reduced. The reduced temperature of the heat exchange medium is equal to the difference of the temperature sensor greater than 80°C, so that the material temperature is kept balanced at 80°C.

[0058] (2) When it is monitored that the material temperature in the reaction pipeline rises above 85°C, the CO2 purification system introduces CO2 gas at a gas temperature of 60°C into the carbon dioxide inlet, replenishes the CO2 pressure to 4MPa, and reduces the temperature of the heat exchange medium in the jacket. The lowered temperature of the heat exchange medium is the difference between the material temperature and 80°C, until the material temperature drops to 80°C.

[0059] After 3 hours of reaction, the density increased uniformly to 1.12 g / cm 3 And stable (change within 5 minutes is less than 0.01g / cm 3 ), at which point the reaction is complete, the temperature is lowered and the product is taken out. After the catalyst is removed by the catalyst filter, the main and by-products are separated using a scraper evaporator.

[0060] The above-mentioned DMC catalyst is a zinc-cobalt double metal cyanide complex catalyst obtained by reacting water-soluble metal salts of zinc and cobalt in a water-soluble solvent. The specific preparation method is as follows: Weigh potassium hexacyanocobaltate and zinc bromide in a molar ratio of 1:4, dissolve them in an aqueous solvent containing water and tert-butyl alcohol, and continue to stir, and the total mass of the metal salt (i.e., cobalt salt and zinc salt) and the mass ratio of the aqueous solvent are 1:5. Add inorganic acid and organic acid, the inorganic acid is dilute hydrochloric acid, the pH value is 2, the organic acid is glutaric acid, the molar ratio of inorganic acid to organic acid is 5:1, and the total molar number of metal salts to the molar number of acid is 4:1, stir at a temperature of 10-100°C for several hours, and precipitate is continuously generated. The above precipitate is filtered and dried to obtain a filter cake. The filter cake is re-slurried and washed with an aqueous solvent at a temperature of 10-100°C, specifically, the washing temperature is 100°C, washing for 3 minutes, stirring for several hours, and then filtered and dried to obtain a filter cake, and the above slurrying, washing, and drying steps are repeated for multiple times at a temperature of 10-100°C until the pH value of the system liquid is 6-7, specifically, the temperature is 60°C, and each time for 6 minutes. The filter cake is further dried under vacuum conditions at 80-100°C to obtain the final catalyst, and the catalyst is processed into powder particles by mechanical grinding under anhydrous drying conditions before use.

[0061] The purified product was sampled and analyzed. Specifically, the polymerization reaction product (polycarbonate-polyether polyol and cyclic propylene carbonate and unreacted propylene oxide) was sampled and collected in a container, and the polymerization reaction product sample was characterized by nuclear magnetic resonance hydrogen spectrum to calculate the ratio of polymer to cyclic small molecules in the crude product. After the polymer was purified, the nuclear magnetic resonance hydrogen spectrum test was performed again to calculate the ratio of polycarbonate chain segments to polyether chain segments on the polymer main chain. There are only two structures, polycarbonate chain segments and polyether chain segments, on the polymer main chain, and the sum of the two percentages is 100%.

[0062] With the help of 1 The amount of carbon dioxide introduced into the resulting polycarbonate polyether polyol (carbonate segment content) and the ratio of propylene carbonate (cyclic carbonate) to polycarbonate polyether polyol were determined by H-NMR (Bruker, DPX400, 400 MHz; pulse program zg30, waiting time d1:10 s, 64 scans). In each case, the sample was dissolved in deuterated chloroform. 1 The relevant resonant proton peaks in H-NMR (based on TMS=0ppm) are as follows: Among them, 5.0ppm and 4.2ppm belong to the proton peaks of the methine and methylene on the polycarbonate chain, 4.9ppm, 4.5ppm and 4.1ppm belong to the proton peaks of the methine and methylene in the five-membered ring carbonate, and 3.5-3.8ppm belong to the proton peak of the ether chain. The capital letter A plus a numerical subscript represents the integrated area of ​​the peak at a certain ppm on the nuclear magnetic resonance hydrogen spectrum, for example, A 5.0represents the integrated area of ​​the peak at 5.0 ppm. 1 The integral area of ​​the H-NMR spectrum and its related proton peaks is used to calculate the carbonate chain ratio (molar ratio) F in the copolymerization reaction. CO2 and cyclic carbonate content mass fraction W PC、 The amount of carbon dioxide embedded 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%.

[0063] The coefficient 44 is the molar mass of carbon dioxide, the coefficient 58 is the molar mass of PO (propylene oxide), and the coefficient 102 is the sum of the molar masses of carbon dioxide (molar mass 44 g / mol) and PO (molar mass 58 g / mol).

[0064] The formula for calculating the product conversion rate n is n=m×(1-M CO2 ) / (Mm×M CO2 ), wherein m is the mass of the product after removing propylene oxide, and M is the total sample mass containing propylene oxide.

[0065] The polymer number average molecular weight (Mn) and polymer molecular weight polydispersity index (PDI) were determined by gel permeation chromatography (GPC).

[0066] The hydroxyl value (OHV) is obtained by GB / T 12008.3-2009 Plastic polyether polyols Part 3: Determination of hydroxyl value.

[0067] The final product was tested for colorimetry. 5g of the test object was placed in a cuvette and the cuvette was placed in a dark environment to reduce the influence of the light source on the test and cause errors. The NR10QC colorimeter was used for the test, and the test data included three basic indicators: L*, a*, and b*.

[0068] The L* value represents the color brightness, L*=0 indicates black, and L*=100 indicates white.

[0069] The a* value represents the position between red / magenta and green, with negative a* values ​​indicating green and positive a* values ​​indicating magenta.

[0070] The b* value represents the position between yellow and blue, with a negative b* value indicating blue and a positive b* value indicating yellow.

[0071] The smaller the absolute values ​​of a* and b*, the better; the smaller they are, the closer they are to colorless.

[0072] The test results are shown in Table 1 below: Table 1

[0073] As can be seen from Table 1, the production process provided by the embodiment of the present invention can fully react the raw materials at 80°C, and the molecular weight distribution of the prepared polycarbonate polyether polyol is narrower, distributed around 1.1; the b* value is less than 0.1 and close to 0, that is, the product does not turn yellow; the carbonate chain ratio is higher, at more than 55%, that is, the carbon dioxide fixation rate is high. In addition, the reaction time is very short, and it only takes 3 hours to reach a given conversion rate, and the energy consumption is relatively less.

[0074] Example 2 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, referring to the production process in Example 1, which differs from that in Example 1 in that: The raw materials added were: 32L propylene oxide, 16g DMC catalyst, 2080g bisphenol A, and an 8L×8 integrated tube reactor was used. The circulation flow rate was controlled to complete one cycle in 10min (the flow rate of the circulation pump was about 2400g / min).

[0075] Example 3 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, referring to the production process in Example 1, which differs from that in Example 1 in that: The amount of raw materials added is: 300L propylene oxide, 150g DMC catalyst, 19500g bisphenol A, and a 240L×2 integrated tube reactor is used. The diameter of the reaction pipe is 220mm and the length is 8600mm. When the liquid in the reaction pipe is greater than 10%, the circulation pump is turned on, and the circulation flow rate is controlled to complete a cycle in 10 minutes (the flow rate of the circulation pump is about 22500g / min).

[0076] Example 4 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, referring to the production process in Example 1, which differs from that in Example 1 in that: The gas-liquid volume ratio is 1:4.

[0077] Example 5 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, referring to the production process in Example 1, which differs from that in Example 1 in that: The length-to-diameter ratio of the reaction pipe is 40:1.

[0078] Example 6 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, referring to the production process in Example 1, which differs from that in Example 1 in that: The reaction temperature was 70°C.

[0079] Example 7 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, referring to the production process in Example 1, which differs from that in Example 1 in that: The reaction temperature was 85°C.

[0080] Example 8 This embodiment provides a bisphenol A type low molecular weight polycarbonate polyether polyol, referring to the production process in Example 1, which differs from that in Example 1 in that: The circulation flow rate is controlled to complete one cycle in 15 minutes (the flow rate of the circulation pump is about 900g / min).

[0081] The products obtained in Examples 2-8 were tested according to the method in Example 1. The test results are shown in Table 2 below.

[0082] Table 2

[0083] Relative to Example 1, Example 2 and Example 3 were scaled up in production at different ratios. As can be seen from Table 2, there were no significant fluctuations in the molecular weight, molecular weight distribution, conversion rate and other indicators of the polymers obtained in Example 2 and Example 3. Relative to Example 1, Examples 4-8 made certain adjustments in the gas-liquid ratio, reaction temperature and liquid circulation speed. Within a certain range, changing one condition alone did not cause significant fluctuations in the molecular weight, molecular weight distribution, conversion rate and other indicators of the compound. The integrated tube-in-tube reaction device provided in the embodiment of the present invention will not affect the molecular weight, molecular weight distribution, conversion rate and other indicators of the polymer after being scaled up, and there is no obvious amplification effect. Moreover, when the production process is scaled up, the same parallel reaction pipelines can share a set of heating equipment, which can reduce energy consumption while carrying out production.

[0084] Comparative Example 1 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, referring to the production process in Example 1, which differs from that in Example 1 in that: The pressure of the CO2 introduced was always 3MPa, and no CO2 pressurization compensation was performed when the temperature rose sharply.

[0085] Comparative Example 2 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, referring to the production process in Example 1, which differs from that in Example 1 in that: During the temperature rising process, the temperature of the heat exchange medium in the jacket 105 of the reaction pipe is controlled to be 80°C until the reaction temperature in the reaction pipe rises to 80°C.

[0086] Comparative Example 3 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, which is different from that in Example 1 in that: The liquid circulation flow rate in the reaction unit is 25 min to complete one cycle, and the other reaction conditions are consistent with Example 1.

[0087] Comparative Example 4 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, which is different from that in Example 1 in that: When the polymerization reaction is carried out after the temperature is raised, the temperature is not monitored during the polymerization reaction, and the temperature of the heat exchange medium in the jacket is always maintained at 80°C.

[0088] Comparative Example 5 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, which is different from that in Example 1 in that: The gas-liquid volume ratio in the reaction pipeline is 1:5, that is, the reaction raw materials are increased, and the other reaction conditions are consistent with Example 1.

[0089] Comparative Example 6 This comparative example provides a bisphenol A type low molecular weight polycarbonate polyether polyol, and the reaction device is different from that of Example 1 in that: the reaction pipeline does not have a dispersion sheet 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: 8L propylene oxide, 4g DMC catalyst and 520g bisphenol A were added to the premixing kettle respectively, and 0.4MPa carbon dioxide was introduced and mixed and stirred at a temperature of 40°C. After stirring for 1h, the mixture was pressed into an 8L×2 reactor array, and the diameter of a single reaction pipe was 100mm and the length of the reaction pipe was 1000mm. After all the mixture was pressed in, carbon dioxide was introduced into the reaction pipe to 3MPa and the pressure was maintained. A booster pump was used to compress the carbon dioxide on the upper part of the pipe and introduce it from the bottom of the pipe so that the material inside the pipe could fully dissolve the carbon dioxide. The pressure ratio was 25:1. After reacting at a temperature of 80°C for 3h, the density was uniformly increased to 1.12g / cm 3 The reaction is complete and the temperature is lowered to remove the product. After the catalyst is removed by the catalyst filter, the main and by-products are separated by a scraper evaporator.

[0090] The products obtained in Comparative Examples 1-6 were tested according to the method in Example 1. The test results are shown in Table 3 below.

[0091] Table 3

[0092] Compared with 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 likely to cause large temperature changes when the reaction is intense, and low-temperature CO2 supplementation is required to stabilize the temperature of the material in the reaction pipe, causing the product color to turn yellow. At the same time, the CO2 consumption rate in the liquid material becomes faster, and there is no excessive CO2 supplementation, resulting in the CO2 dissolution rate not keeping up with the consumption rate, resulting in excessively high PDI and a relatively low ester content.

[0093] Compared with Example 1, in Comparative Example 2, when heating, the reaction pipe is directly heated with a heat exchange medium of a higher temperature, and the heating process is not finely controlled. This method will cause uneven heating, and the temperature of the material close to the tube wall will rise quickly, causing local rapid reaction to release heat, resulting in local excessive temperature, making the molecular weight distribution wider, and the b* value of the product higher, that is, the color turns yellow.

[0094] Compared with Example 1, Comparative Example 3 reduces the liquid circulation speed. The lower circulation speed will cause the temperature of the reacted materials to accumulate, resulting in explosion and high-temperature oxidation of bisphenol A, causing the product to turn yellow.

[0095] Compared with Example 1, Comparative Example 4 does not perform temperature control during the polymerization reaction, which will cause temperature accumulation of the reaction materials, resulting in high-temperature oxidation of bisphenol A and causing the product to turn yellow.

[0096] Compared with Example 1, Comparative Example 5 has a lower gas-liquid ratio. The reduction in the gas-liquid ratio not only causes the mass and heat transfer efficiency in the CO2 region to deteriorate, reducing the ester content and turning the color yellow, but also increases the heat of generation of the material during the reaction, increases the difficulty of temperature control, and is very easy to explode.

[0097] Compared with Example 1, Comparative Example 6 does not have a gas-liquid mixing heat conduction zone, and uses gas circulation in the pipeline to complete gas-liquid mass transfer. The actual conversion rate of this method is lower and the molecular weight distribution (PDI) is wider. Since there is no liquid circulation to continuously mix the materials and release heat, the reaction speed is faster, the heat generated is more difficult to release and remove in a short time, the color is yellowish, and it is more prone to explosion.

[0098] It can be seen from the above embodiments and comparative examples that the production process of bisphenol A type low molecular weight polycarbonate polyether polyol of the present invention is carried out in an integrated tubular reaction device with a special structure, and the material can be circulated in the reaction pipeline for polymerization, and a specific process control program is matched, so that the PDI of the obtained product is small, the carbon dioxide conversion rate is high, and the product is close to white, which effectively solves the yellowing problem of the product caused by the one-step production process in the prior art, and the product molecular weight distribution is narrow, and there is no amplification effect, the product molecular weight is highly controllable, the production is stable between batches, and the product quality is high. At the same time, the production process is safe and controllable, it is not easy to produce implosion, there is no amplification effect, and it is suitable for industrial large-scale production.

[0099] The embodiments described above are part of the embodiments of the present invention, rather than all of the embodiments. The detailed description of the embodiments of the present invention is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work 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 tube-in-tube reaction device having at least one reaction pipeline, and the production process comprises: Introducing a premixture into the reaction pipe at one time, and introducing CO2 of a first pressure value; wherein the premixture is obtained by introducing CO2 into all the epoxy compound, bisphenol A and catalyst for premixing; The premix is ​​heated and circulated in a reaction pipe to perform a polymerization reaction, and then separated to obtain a bisphenol A type low molecular weight polycarbonate polyether polyol; wherein, during the polymerization reaction, slow temperature rise control and gas pressure compensation are performed so that the molecular weight polydispersity index (PDI) of the bisphenol A type low molecular weight polycarbonate polyether polyol does not exceed 1.5, and in the L*a*b* color system, the b* value does not exceed 0.1; The slow temperature rise control includes: controlling the heating temperature of the reaction pipe and the temperature difference of the material in the reaction pipe to be no more than 3-5°C, so that the material in the reaction pipe is heated to 75-85°C and then undergoing a polymerization reaction; the gas pressurization compensation includes: during the polymerization reaction, when the temperature of the material in the reaction pipe rises sharply, introducing CO2 gas of a second pressure value into the reaction pipe until the temperature of the material in the reaction pipe drops to 75-85°C, wherein the judgment index for the sharp rise in material temperature is that the temperature rise is not less than 5°C 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 to be 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, it also includes: controlling the lowered temperature of the heat exchange medium to be roughly equal to the increased temperature of the material in the reaction pipe, so that the temperature of the material in the reaction pipe is maintained at 75~85°C.

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 2-6 MPa, and the second pressure value is 4-8 MPa.

5. The production process of bisphenol A type low molecular weight polycarbonate polyether polyol according to claim 1, characterized in that: The integrated tube-in-tube reaction device comprises a premixing unit and a reaction unit, wherein the premixing unit is premixed; the reaction unit comprises a circulation pump and a plurality of reaction pipes, wherein the circulation pump is used to circulate the material in the plurality of reaction pipes, and the circulation flow rate of the circulation pump is 10 to 15 minutes to complete one cycle; or, the circulation flow rate of the circulation 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: A plurality of the reaction pipes are arranged in parallel, and the feed end of each reaction pipe intersects with a liquid distributor through a connecting pipe, and the discharge end converges to the circulation pump through 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 replenishment port for CO2 to enter; the mixed products flowing out of the plurality of reaction pipes converge together at the circulation pump, are pumped into the liquid distributor by the circulation pump, are dispersed into the plurality of reaction pipes, and then pass through the reaction pipe to reach the discharge end, completing a 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 of the premixing unit, the temperature of the premixing unit is controlled to be 0-40°C, the pressure is controlled to be 0.1-2MPa, and the premixing time is controlled to be 1-2h; when the premixed mixture of the premixing unit is put into the reaction unit, the temperature of the reaction pipe is controlled to be 35-45°C; when the density of the reaction product reaches 1.1-1.3 g / cm 3 , and the change is less than 0.01g / cm within 5min 3 The reaction is terminated.

9. The production process of bisphenol A type low molecular weight polycarbonate polyether polyol according to claim 1, characterized in that: The metal elements of the catalyst are only two metal elements, zinc and cobalt, except for impurities; the catalyst is obtained by reacting water-soluble metal salts of zinc and cobalt in a water-soluble solvent, and the water-soluble metal salt of cobalt is a cyanide salt of cobalt; the catalyst is modified by a mixed acid during synthesis, and 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.

10. A bisphenol A type low molecular weight polycarbonate polyether polyol prepared according to 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): Formula (1); Wherein, in formula (1), R1 and R2 are selected from formula (2) or OH, Formula (2); Wherein, in formula (2), 1≤n≤22, 1≤m≤39, * represents 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 chain segment ratio F CO2 ≥45%.

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