Synthesis method of olefin-polymer monomer alternating copolymer with narrow molecular weight distribution

Abstract

The present invention provides a method for synthesizing an olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution. The synthetic method comprises the following steps: step S1, a reaction raw material including a solvent for polymerization, an olefin, a polymerized monomer, a molecular weight regulator, and an initiator is subjected to a polymerization reaction in a tandem reaction system to obtain a polymerization product; step S2, a raw material including a polymerization product and a precipitant is subjected to a precipitation reaction and then subjected to a solid-liquid separation treatment to obtain an olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution; wherein the polymerized monomer includes an active functional group and a carbon-carbon double bond; and the olefin is an olefin of C2 to C6. The present invention performs a polymerization reaction in a tandem reaction system, and a kettle-tube reaction system is constructed by combining a tubular reactor with a kettle reaction, so that the tandem reaction system has better heat and mass transfer effects. And the post-processing process of the olefin-polymerized monomer alternating copolymer is simple, and the market and industrialization prospects are good.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material preparation, in particular to a method for synthesizing an olefin-polymer monomer alternating copolymer with a narrow molecular weight distribution. Background Art

[0002] As a functional polymer material, ethylene-maleic anhydride copolymer has a wide range of uses in engineering plastic chain extension, high-performance composite materials, nylon impregnation, ink dispersion, microencapsulation, and filtration membrane formation, and has received great attention.

[0003] Ethylene-maleic anhydride copolymers are distinguished by their molecular weight, and they have many application directions. Ethylene-maleic anhydride copolymers can be used for surface active treatment of glass fiber, carbon fiber, inorganic mineral powder, filler and flame retardant, etc., especially as glass fiber sizing agent, its maleic anhydride group reacts with amino or silanol of silane coupling agent in glass fiber, and the other part reacts with amino and hydroxyl of plastic resin (PA, PBT, PET, PC, etc.) during the modification process, thereby enhancing the bonding degree between glass fiber and resin, and greatly improving the mechanical properties and heat resistance of composite materials. Ethylene-maleic anhydride copolymers can be used as chain extension, viscosity enhancement and branching reaction additives for engineering plastics, as additives to improve glue adhesion, as microcapsule emulsifiers and size regulators, as high-performance ink dispersants, and as textile sizing agents, and they have good market prospects.

[0004] The polymerization process of ethylene-maleic anhydride copolymer is a free radical polymerization process. The existing technology mostly uses a reactor for polymerization. The amount of monomers in the polymerization reactor is large, and implosion is prone to occur. The reaction heat is difficult to withdraw and the reaction is difficult to control. In addition, when the polymerization is carried out using the existing kettle reactor, it is a full back-mixing continuous reaction, which makes it difficult to ensure that the kinetic chain lengths of the free radicals generated by decomposition during the polymerization process are the same or similar, resulting in the appearance of high molecular weight products in the obtained polymer and too wide molecular weight distribution. Summary of the invention

[0005] The main purpose of the present invention is to provide a method for synthesizing an ethylene-maleic anhydride alternating copolymer with a narrow molecular weight distribution, so as to solve the problem that when a kettle reactor is used as a polymerization reactor in the prior art, the ethylene-maleic anhydride alternating copolymer prepared has a too wide molecular weight distribution.

[0006] In order to achieve the above-mentioned purpose, according to one aspect of the present invention, there is provided a method for synthesizing an olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution, the method comprising the following steps: step S1, subjecting the reaction raw materials including a polymerization solvent, olefin, polymerized monomer, molecular weight regulator and initiator to a polymerization reaction in a series reaction system to obtain a polymerization reaction product; step S2, subjecting the raw materials including the polymerized reaction product and a precipitant to a precipitation reaction and then to a solid-liquid separation treatment to obtain an olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution; wherein the polymerized monomer includes an active functional group and a carbon-carbon double bond; the olefin is a C2 to C6 olefin; and the series reaction system includes a kettle reactor and a tubular reactor connected in series in sequence.

[0007] Furthermore, the above-mentioned active functional group is selected from any one or more of a carboxylic acid group, anhydride group and an amide group, and the preferred polymerization monomer is selected from any one or more of maleic anhydride, maleic acid, maleimide, itaconic acid and itaconic anhydride; and / or, the mass of the polymerization monomer is 10% to 40% of the total mass of the reaction raw materials.

[0008] Furthermore, the above-mentioned olefin is a C2-C4 olefin, and preferably the olefin is ethylene.

[0009] Furthermore, the above-mentioned step S2 comprises: step S21, separating the polymerization reaction product to obtain a homogeneous product liquid and olefins; step S22, subjecting the raw materials including the homogeneous product liquid and the precipitant to a precipitation reaction to obtain a polymer precipitate; step S23, centrifuging and devolatilizing the polymer precipitate to drying in sequence to obtain an olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution; and / or the olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution is preferably an ethylene-maleic anhydride alternating copolymer, the weight average molecular weight of the ethylene-maleic anhydride alternating copolymer is 3000 to 300000 g / mol, the molecular weight distribution coefficient of the ethylene-maleic anhydride alternating copolymer is <2.2, the content of the corresponding molecular segment of ethylene in the ethylene-maleic anhydride alternating copolymer is ≤30%, and the content of the corresponding molecular segment of maleic anhydride in the ethylene-maleic anhydride alternating copolymer is ≥70%; and / or the moisture content of the polymer precipitate after centrifugation is 30% to 50%.

[0010] Furthermore, the precipitant is selected from any one or more of n-hexane, diethyl ether, n-heptane, n-pentane or n-butyl ether; and / or the volume ratio of the precipitant to the solvent used for polymerization is 1:1 to 15:1, preferably 2:1 to 15:1.

[0011] Furthermore, the devolatilization drying pressure is -0.085 to -0.098 MPa, and / or the devolatilization drying temperature is 60 to 120° C.; and / or the moisture content of the polymer precipitate after devolatilization drying is 0.01% to 0.05%.

[0012] Furthermore, the above-mentioned autoclave reactor-tubular reactor comprises a high-pressure reactor, a high-pressure loop reactor and a high-pressure circulation pump connected in series in sequence, and step S1 comprises: step S11, firstly introducing a first polymerization solvent into the series reaction system for circulation through the high-pressure circulation pump, then introducing ethylene to replace the positive pressure of ethylene in the series reaction system to 0.1-0.5 MPa, and maintaining the temperature in the series reaction system at the temperature required for the polymerization reaction, and replenishing ethylene into the series reaction system to the pressure required for the polymerization reaction; step S12, mixing raw materials including a second polymerization solvent, a molecular weight regulator and a polymerization monomer to obtain a first reaction liquid; step S13, mixing raw materials including an initiator and a third polymerization solvent to obtain a second reaction liquid; step S14, respectively adding the first reaction liquid and the second reaction liquid into the autoclave reactor; and using the high-pressure circulation pump to make the reaction raw materials in the high-pressure reaction The polymerization reaction is circulated in the autoclave and the high-pressure loop reactor; wherein the amount of the solvent used for the polymerization is the total amount of the first polymerization solvent, the second polymerization solvent and the third polymerization solvent, wherein the amount of the first polymerization solvent is 15% to 30% of the total mass of the reactants, the amount of the second polymerization solvent is 30% to 50% of the total mass of the reactants, and the amount of the third polymerization solvent is 3% to 10% of the total mass of the reactants; and / or the first polymerization solvent, the second polymerization solvent and the third polymerization solvent are independently selected from any one or more of methyl acetate, acetone, N,N-dimethylformamide and dimethyl sulfoxide; preferably, the residence time of the reaction raw materials in the high-pressure loop reactor is controlled to be 30min to 4h, preferably 30min to 2h; preferably, the time for adding the first reaction liquid and the second reaction liquid into the autoclave reactor is independently 30min to 10h, preferably 30min to 4h.

[0013] Furthermore, in the above step S1, the molecular weight regulator is selected from any one or more of 2,4-diphenyl-4-methyl-1-pentene, n-dodecyl mercaptan, 3-mercaptopropionic acid, 2-mercaptoethanol, sodium hypophosphite, sodium formate, sodium pyrosulfite, and sodium bisulfite; preferably, the amount of the molecular weight regulator is 0.01% to 5%, preferably 0.5 to 3%, of the amount of the polymerization monomer.

[0014] Furthermore, in the above step S1, the molar ratio of the initiator to the polymerization monomer is (0.005-0.015):1, and / or the initiator is an azo compound and / or a peroxide compound, the azo compound is selected from any one or more of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptanenitrile, azobiscyclohexylcarbonitrile and dimethyl azobisisobutyrate; and / or the peroxide compound is selected from any one or more of benzoyl peroxide, dodecyl peroxide, diisopropyl peroxide and diisopropyl peroxydicarbonate.

[0015] Furthermore, in the above step S1, the polymerization reaction temperature is 55-150° C., and / or the polymerization reaction time is 1-12 h; preferably, the olefin is ethylene, and the ethylene pressure during the polymerization reaction is 2-20 MPa.

[0016] By applying the technical scheme of the present invention, the tubular reactor is heated quickly, has good heat transfer effect, is easy to control temperature, and has stable temperature. It can ensure that the initiator enters the reactor and immediately decomposes to generate free radicals and initiate polymerization, and there is no problem of initiation and decomposition at different times due to temperature gradient. The tubular reactor is convenient for realizing high-speed flow of monomers and polymers in the reactor, and can avoid the problem of polymer adhesion in the reactor due to excessively high reactor wall temperature, which affects heat conduction and polymerization degradation. The present invention conducts polymerization reaction in a series reaction system, and constructs a reactor-tube reaction system by combining a tubular reactor with a reactor reaction, so that the series reaction system has better heat and mass transfer effects. The mixture of polymerized monomers in the reaction raw materials and olefin-polymerized monomer alternating copolymers with narrow molecular weight distribution flows in a plug flow manner, so that the back-mixing problem generated when using a reactor reactor for continuous polymerization can be avoided, and the kinetic chain length from free radical self-chain initiation to true kinetic termination is the same or basically similar, and the concentrations of polymerized monomers, initiators and molecular weight regulators in the reaction can be regulated to obtain ethylene-maleic anhydride copolymer products with narrow molecular weight distribution. The above method is simple to operate, has mild reaction conditions, low energy consumption and cost, is green and environmentally friendly, and the post-treatment process of the olefin-polymerization monomer alternating copolymer with a narrow molecular weight distribution is simple and easy to separate and purify. The first polymerization solvent and other raw materials can be recycled, and it has good market and industrial prospects. DETAILED DESCRIPTION

[0017] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present invention will be described in detail below in conjunction with the embodiments.

[0018] As analyzed in the background technology, when a kettle reactor is used as a polymerization reactor in the prior art, the prepared ethylene-maleic anhydride alternating copolymer has the problem of too wide molecular weight distribution. To solve this problem, the present invention provides a method for synthesizing ethylene-maleic anhydride alternating copolymer.

[0019] In a typical embodiment of the present application, a method for synthesizing an olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution is provided, and the method comprises the following steps: step S1, subjecting the reaction raw materials including a polymerization solvent, an olefin, a polymerized monomer, a molecular weight regulator, and an initiator to a polymerization reaction in a series reaction system to obtain a polymerization reaction product; step S2, subjecting the raw materials including the polymerized reaction product and a precipitant to a precipitation reaction and then to a solid-liquid separation treatment to obtain an olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution; wherein the polymerized monomer includes an active functional group and a carbon-carbon double bond; the olefin is an olefin of C2 to C6; and the series reaction system includes a kettle reactor and a tubular reactor connected in series in sequence.

[0020] The tubular reactor is quick to heat, has good heat transfer effect, is easy to control temperature, and has stable temperature. It can ensure that the initiator enters the reactor and immediately decomposes to generate free radicals and initiate polymerization, and there is no problem of initiation and decomposition at different times due to temperature gradient. The tubular reactor is convenient for realizing high-speed flow of monomers and polymers in the reactor, and can avoid the problem of polymer adhesion in the reactor due to excessively high reactor wall temperature, which affects heat conduction and polymerization degradation. The present invention carries out polymerization reaction in a tandem reaction system, and constructs a reactor-tube reaction system by combining a tubular reactor with a tank reaction, so that the tandem reaction system has better heat and mass transfer effects. The mixture of the polymerized monomers in the reaction raw materials and the olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution flows in a piston flow manner, so that the back-mixing problem generated when the tank reactor is used for continuous polymerization can be avoided, and the kinetic chain length from free radical self-chain initiation to true kinetic termination is the same or basically similar, and the concentrations of the polymerized monomers, initiators and molecular weight regulators in the reaction can be regulated to obtain ethylene-maleic anhydride copolymer products with a narrow molecular weight distribution. The above method is simple to operate, has mild reaction conditions, low energy consumption and cost, is green and environmentally friendly, and the post-treatment process of the olefin-polymerization monomer alternating copolymer with a narrow molecular weight distribution is simple and easy to separate and purify. The first polymerization solvent and other raw materials can be recycled, and it has good market and industrial prospects.

[0021] In one embodiment of the present application, the above-mentioned active functional group is selected from any one or more of a carboxylic acid group, an anhydride group and an amide group, and the preferred polymerization monomer is selected from any one or more of maleic anhydride, maleic acid, maleimide, itaconic acid, itaconic anhydride, and further, the preferred polymerization monomer is maleic anhydride; and / or, the mass of the polymerization monomer is 10% to 40% of the total mass of the reaction raw materials.

[0022] The above-mentioned polymerized monomer preferably includes an active functional group and a carbon-carbon double bond, so that it has a higher reactivity, which is conducive to the effective alternating copolymerization of the polymerized monomer and the olefin, so that the olefin-polymerized monomer copolymer forms an olefin-polymerized monomer alternating copolymer with specific functions and a wide range of applications. At the same time, by preferably selecting the polymerized monomer mass ratio within the above range, it is conducive to improving the conversion rate of the polymerized monomer, making the performance of the polymer more stable, and meeting the needs of different application fields.

[0023] In one embodiment of the present application, the above-mentioned olefin is a C2-C4 olefin, and preferably the olefin is ethylene.

[0024] The above-mentioned olefins preferably have higher reactivity, which is conducive to forming alternating copolymers with polymerization monomers, and C2-C4 olefins are widely available in industrial production and have low costs.

[0025] In one embodiment of the present application, the above-mentioned step S2 includes: step S21, separating the polymerization reaction product to obtain a homogeneous product liquid and olefins; step S22, subjecting the raw materials including the homogeneous product liquid and the precipitant to a precipitation reaction to obtain a polymer precipitate; step S23, centrifuging and devolatilizing the polymer precipitate in sequence to obtain an olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution; and / or the olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution is preferably an ethylene-maleic anhydride alternating copolymer, the weight average molecular weight of the ethylene-maleic anhydride alternating copolymer is 3000 to 300000 g / mol, the molecular weight distribution coefficient of the ethylene-maleic anhydride alternating copolymer is <2.2, the content of the corresponding molecular segment of ethylene in the ethylene-maleic anhydride alternating copolymer is ≤30%, and the content of the corresponding molecular segment of maleic anhydride in the ethylene-maleic anhydride alternating copolymer is ≥70%; and / or the moisture content of the polymer precipitate after centrifugation is 30% to 50%.

[0026] The present application uses the above steps to post-treat the polymerization product, on the one hand, to effectively separate the ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution from the polymerization product, and on the other hand, to recover olefins, thereby helping to improve the recyclability of olefins and reduce their pollution to the environment, and the treatment process is simple and the cost is low. The ethylene-maleic anhydride alternating copolymer having the above weight-average molecular weight range, molecular weight distribution coefficient, the content of the corresponding molecular segment of ethylene in the ethylene-maleic anhydride alternating copolymer within the above range, and the content of the corresponding molecular segment of maleic anhydride in the ethylene-maleic anhydride alternating copolymer within the above range has more stable performance and a wider range of applications.

[0027] In one embodiment of the present application, the precipitant is selected from any one or more of n-hexane, ethyl ether, n-heptane, n-pentane or n-butyl ether; and / or the volume ratio of the precipitant to the solvent used for polymerization is 1:1 to 15:1, preferably 2:1 to 15:1.

[0028] By controlling the type of precipitant and controlling the volume ratio of the precipitant to the first polymerization solvent within the above range, it is beneficial to optimize the formation process of the polymer precipitate, improve the precipitation efficiency, reduce the loss of the ethylene-maleic anhydride alternating copolymer, and is also beneficial to the subsequent centrifugal separation and drying of the polymer precipitate; in addition, the recovered first polymerization solvent can be processed and recycled, thereby reducing production costs and improving economy and environmental protection.

[0029] In one embodiment of the present application, the devolatilization drying pressure is -0.085 to -0.098 MPa, and / or the devolatilization drying temperature is 60 to 120° C.; and / or the moisture content of the polymer precipitate after devolatilization drying is 0.01% to 0.05%.

[0030] By controlling the devolatilization drying conditions within the above range, it is beneficial to effectively recover the solvent and reduce the residual moisture in the polymer precipitate as much as possible, thereby improving the purity and storage property of the ethylene-maleic anhydride alternating copolymer; at the same time, it is preferred that the moisture content of the polymer precipitate after devolatilization drying is within the above range, ensuring that the ethylene-maleic anhydride alternating copolymer has stable physical and chemical properties.

[0031] In one embodiment of the present application, the above-mentioned autoclave reactor-tubular reactor comprises a high-pressure reactor, a high-pressure loop reactor and a high-pressure circulation pump connected in series in sequence, and step S1 comprises: step S11, first introducing a first polymerization solvent into the series reaction system for circulation through a high-pressure circulation pump, and then introducing ethylene to replace the positive pressure of ethylene in the series reaction system to 0.1 to 0.5 MPa, and maintaining the temperature in the series reaction system at the temperature required for the polymerization reaction, and replenishing ethylene into the series reaction system to the pressure required for the polymerization reaction; step S12, mixing raw materials including a second polymerization solvent, a molecular weight regulator and a polymerization monomer to obtain a first reaction liquid; step S13, mixing raw materials including an initiator and a third polymerization solvent to obtain a second reaction liquid; step S14, respectively adding the first reaction liquid and the second reaction liquid to the autoclave reactor; and using a high-pressure circulation pump to allow the reaction raw materials to be circulated in the high-pressure reactor and The polymerization reaction is circulated in a high-pressure loop reactor; wherein the amount of the solvent used for the polymerization is the total amount of the first polymerization solvent, the second polymerization solvent and the third polymerization solvent, wherein the amount of the first polymerization solvent is 15% to 30% of the total mass of the reactants, the amount of the second polymerization solvent is 30% to 50% of the total mass of the reactants, and the amount of the third polymerization solvent is 3% to 10% of the total mass of the reactants; and / or the first polymerization solvent, the second polymerization solvent and the third polymerization solvent are independently selected from any one or more of methyl acetate, acetone, N,N-dimethylformamide (DMF) and dimethyl sulfoxide (DMSO); preferably, the residence time of the reaction raw materials in the high-pressure loop reactor is controlled to be 30 minutes to 4 hours, preferably 30 minutes to 2 hours; preferably, the time for adding the first reaction liquid and the second reaction liquid into the autoclave reactor is independently 30 minutes to 10 hours, preferably 30 minutes to 4 hours.

[0032] The preferred kettle reactor-tubular reactor of the above structure, wherein the autoclave mainly plays the effect of stirring and mixing reaction raw materials, so that the reaction raw materials have a good mixing effect, and the present invention has no special limitation on the process of stirring, and the process well known in the art is selected. The high-pressure circulating pump circulates to realize the high-speed flow and circulation of polymerization monomer and ethylene-maleic anhydride alternating copolymer in the tubular reactor, avoids its backmixing, thereby ensuring that the chain initiation of free radicals is identical or close to the kinetic chain length when the kinetics terminates, and then obtains a copolymer with a small and uniform molecular weight distribution range. Therefore, by connecting the autoclave, the high-pressure loop reactor and the high-pressure circulating pump in series, an integrated reaction process is formed, which not only improves the compactness of the reaction system and the convenience of operation, but also realizes the efficient and continuous transmission of reaction materials between different reactors, reduces the retention and backmixing of materials in the reaction process, optimizes reaction conditions and feeding process, improves the controllability and safety of reaction, and ensures the continuity and stability of reaction. Furthermore, by controlling the time for adding the first reaction liquid and the second reaction liquid to the autoclave reactor within the above range, it is helpful to accurately adjust the concentration of the reaction raw materials. Preferably, controlling the residence time of the reaction raw materials in the high-pressure loop reactor within the above range not only helps to prolong the controllable time of the reaction, but also helps to promote the kinetic chain length of the free radicals from chain initiation to kinetic termination to be the same or basically similar, thereby achieving effective control of the molecular weight and molecular weight distribution of the ethylene-maleic anhydride alternating copolymer, achieving a higher conversion rate of the polymerized monomers, and finally obtaining an ethylene-polymerized monomer alternating copolymer product with stable performance and narrow molecular weight distribution, so that the synthesis method of the present invention has good industrial prospects and application potential.

[0033] In one embodiment of the present application, in the above step S1, the molecular weight regulator is selected from any one or more of 2,4-diphenyl-4-methyl-1-pentene, n-dodecyl mercaptan, 3-mercaptopropionic acid, 2-mercaptoethanol, sodium hypophosphite, sodium formate, sodium pyrosulfite, and sodium bisulfite; the preferred amount of the molecular weight regulator is 0.01% to 5% of the amount of the polymerization monomer, preferably 0.5 to 3%.

[0034] It is preferred to control the type and amount of the molecular weight regulator within the above range, which is beneficial to adjusting the molecular weight of the ethylene-maleic anhydride alternating copolymer, so that the molecular weight distribution of the final ethylene-maleic anhydride alternating copolymer is narrower, the performance is more stable, and it is easier to meet the needs of specific application fields.

[0035] In one embodiment of the present application, in the above step S1, the molar ratio of the initiator to the polymerization monomer is (0.005-0.015):1, and / or the initiator is an azo compound and / or a peroxide compound, the azo compound is selected from any one or more of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptanenitrile, azobiscyclohexylcarbonitrile and dimethyl azobisisobutyrate; and / or the peroxide compound is selected from any one or more of benzoyl peroxide, dodecyl peroxide, diisopropyl peroxide and diisopropyl peroxydicarbonate.

[0036] By controlling the initiator type and the molar ratio of the initiator to the polymerization monomer within the above range, it is beneficial to ensure the efficient progress of the polymerization reaction, while reducing the occurrence of side reactions, improving the monomer conversion rate, and reducing the molecular weight distribution coefficient of the ethylene-maleic anhydride alternating copolymer.

[0037] In one embodiment of the present application, in the above step S1, the polymerization reaction temperature is 55-150° C., and / or the polymerization reaction time is 1-12 h; preferably, the olefin is ethylene, and the ethylene pressure during the polymerization reaction is 2-20 MPa.

[0038] It is preferred to control the polymerization reaction conditions within the above range, which is beneficial to ensure the controllability of the polymerization reaction, avoid the occurrence of implosion, and at the same time increase the polymerization rate and conversion rate to obtain an ethylene-maleic anhydride alternating copolymer product with excellent performance and narrow molecular weight distribution.

[0039] The beneficial effects of the present application will be described below in conjunction with specific embodiments and comparative examples.

[0040] Example 1

[0041] The polymerization monomer maleic anhydride, the molecular weight regulator 3-mercaptopropionic acid and the second polymerization solvent acetone solution are mixed to prepare a reaction solution 1 for standby; the initiator benzoyl peroxide and the third polymerization solvent acetone solution are mixed to prepare a reaction solution 2 for standby; wherein the feeding amount of maleic anhydride in the reaction system is 20% of the total polymerization feeding mass, the molar ratio of benzoyl peroxide to maleic anhydride is 0.01:1, the amount of 3-mercaptopropionic acid is 1% of the mass of maleic anhydride, the feeding amount of the second polymerization solvent is 45% of the total polymerization feeding mass, and the feeding amount of the third polymerization solvent is 5% of the total polymerization feeding mass.

[0042] First, the first polymerization solvent acetone solution is introduced into the kettle-tube reaction system for circulation, and the feeding amount of the first polymerization solvent is 25% of the total polymerization feeding mass. Then, ethylene is slowly introduced into the kettle-tube reaction system for displacement. After ethylene is introduced until the system ethylene pressure reaches 0.5MPa, the liquid temperature in the reaction system is raised to 90°C, and the liquid temperature in the system is maintained unchanged. After the ethylene pressure is gradually supplemented to 3MPa, reaction liquid 1 is pumped into the reactor through metering pump 1, and the feeding time is 4h. At the same time, reaction liquid 2 is pumped into the reactor through metering pump 2, and the feeding time is 4h. After the polymerization starts, the average residence time of the raw material liquid in the reactor in the high-pressure loop reactor is controlled to be 30min. The polymerization time, that is, the circulation time of the material solution in the kettle-tube system after the polymerization starts, is 6h, during which the polymerization ethylene pressure is maintained at 3MPa and the polymerization temperature is 90°C.

[0043] After the reaction is completed, the pressure is first released to recover ethylene to the ethylene storage tank, and then the homogeneous product liquid is discharged to the buffer kettle and stirred, and the precipitant n-heptane is added to obtain a polymer precipitate, wherein the volume ratio of n-heptane to acetone is 6:1. The slurry in the buffer kettle after precipitation is then transferred to a centrifugal device, and after centrifugation until the product moisture content is 40%, the wet material is subjected to negative pressure volatilization drying, the drying temperature is 100°C, the drying pressure is -0.095MPa, and the product moisture content is dried to 0.01%. The acetone and n-heptane solvents obtained by centrifugation and volatilization drying are reused for the next batch of polymerization reactions after decoking and distillation.

[0044] The final narrow molecular weight distribution ethylene-maleic anhydride copolymer product had a maleic anhydride conversion rate of 93.7%, a polymer yield of 92.7%, an anhydride value of 74.1%, a weight average molecular weight of 35300 g / mol, a relative molecular weight distribution index of 1.75, and a particle size D98 of 20 μm.

[0045] Example 2

[0046] The difference from Example 1 is that during the polymerization process, the polymerization ethylene pressure is changed to 4 MPa, the polymerization temperature is changed to 110° C., the polymerization time is changed to 8 h, the molar ratio of the initiator benzoyl peroxide to the polymerization monomer maleic anhydride is changed to 0.0065:1, the amount of the molecular weight regulator 3-mercaptopropionic acid is 0.1% of the mass of maleic anhydride, the feeding time of the reaction liquid 1 is changed to 6 h, the feeding time of the reaction liquid 2 is changed to 4 h, and the average residence time of the raw material liquid in the reactor in the high-pressure loop reactor is controlled to be 50 min; and the volume ratio of the precipitant n-heptane to acetone in the post-treatment process is 5:1.

[0047] The final narrow molecular weight distribution ethylene-maleic anhydride copolymer product had a maleic anhydride conversion rate of 95.1%, a polymer yield of 93.3%, an anhydride value of 74.0%, a weight average molecular weight of 46300 g / mol, a relative molecular weight distribution index of 1.83, and a particle size D98 of 22 μm.

[0048] Example 3

[0049] The difference from Example 1 is that during the polymerization process, the polymerization ethylene pressure is changed to 4 MPa, the polymerization temperature is changed to 95° C., the polymerization time is changed to 8 h, the polymerization solvent is changed to methyl acetate, the molar ratio of the initiator benzoyl peroxide to the polymerization monomer maleic anhydride is changed to 0.0085:1, no molecular weight regulator is added, the feeding time of the reaction liquid 1 is changed to 6 h, the feeding time of the reaction liquid 2 is changed to 6 h, and the average residence time of the raw material liquid in the reactor in the high-pressure loop reactor is controlled to be 1 h; in the post-treatment process, the precipitant is changed to n-pentane, and the volume ratio of n-pentane to methyl acetate is 3:1.

[0050] The final narrow molecular weight distribution ethylene-maleic anhydride copolymer product had a maleic anhydride conversion rate of 96.5%, a polymer yield of 92.3%, an anhydride value of 74.0%, a weight average molecular weight of 55200 g / mol, a relative molecular weight distribution index of 1.90, and a particle size D98 of 23 μm.

[0051] Example 4

[0052] The difference from Example 1 is that the amount of maleic anhydride fed is changed to 15% of the total polymerization feed mass, the polymerization ethylene pressure during the polymerization process is changed to 10 MPa, the polymerization temperature is changed to 80° C., the polymerization time is changed to 10 h, the polymerization solvent is changed to DMF, the initiator is changed to azobisisobutyronitrile, and the molar ratio of azobisisobutyronitrile to maleic anhydride is changed to 0.009:1, the molecular weight regulator is changed to 2-mercaptoethanol, the amount of 2-mercaptoethanol is 0.01% of the mass of maleic anhydride, the feeding time of reaction liquid 1 is changed to 10 h, the feeding time of reaction liquid 2 is changed to 4 h, and the average residence time of the raw material liquid in the reactor in the high-pressure loop reactor is controlled to be 2 h; the precipitant is changed to n-pentane in the post-treatment process, and the volume ratio of n-pentane to DMF is 2:1.

[0053] The final narrow molecular weight distribution ethylene-maleic anhydride copolymer product had a maleic anhydride conversion rate of 91.4%, a polymer yield of 91.3%, an anhydride value of 74.1%, a weight average molecular weight of 189400 g / mol, a relative molecular weight distribution index of 2.08, and a particle size D98 of 26 μm.

[0054] Example 5

[0055] The difference from Example 1 is that the amount of maleic anhydride fed is changed to 10% of the total polymerization feed mass, the polymerization ethylene pressure during the polymerization process is changed to 20 MPa, the polymerization temperature is changed to 85° C., the polymerization time is changed to 12 h, the polymerization solvent is changed to DMSO, the initiator is changed to azobisisobutyronitrile, and the molar ratio of azobisisobutyronitrile to maleic anhydride is changed to 0.0065:1, the molecular weight regulator is changed to sodium hypophosphite, and the amount of sodium hypophosphite is 0.05% of the mass of maleic anhydride, the feeding time of reaction liquid 1 is changed to 10 h, the feeding time of reaction liquid 2 is changed to 10 h, and the average residence time of the raw material liquid in the reactor in the high-pressure loop reactor is controlled to be 2 h; the precipitant is changed to n-hexane in the post-treatment process, and the volume ratio of n-hexane to DMF is 2:1.

[0056] The final narrow molecular weight distribution ethylene-maleic anhydride copolymer product had a maleic anhydride conversion rate of 90.7%, a polymer yield of 88.7%, an anhydride value of 74.2%, a weight average molecular weight of 294900 g / mol, a relative molecular weight distribution index of 2.19, and a particle size D98 of 29 μm.

[0057] Example 6

[0058] The difference from Example 1 is that the amount of maleic anhydride fed is changed to 40% of the total polymerization feed mass, the polymerization ethylene pressure during the polymerization process is changed to 3.5 MPa, the polymerization temperature is changed to 110° C., the polymerization time is changed to 6 h, the initiator is changed to dicumyl peroxide, the molar ratio of dicumyl peroxide to maleic anhydride is changed to 0.012:1, the molecular weight regulator is changed to AMSD, the amount of AMSD is 3% of the mass of maleic anhydride, the feeding time of reaction liquid 1 is changed to 4 h, the feeding time of reaction liquid 2 is changed to 2 h, and the average residence time of the raw material liquid in the reactor in the high-pressure loop reactor is controlled to be 1 h; and the volume ratio of n-heptane to acetone in the post-treatment process is 7:1.

[0059] The final narrow molecular weight distribution ethylene-maleic anhydride copolymer product had a maleic anhydride conversion rate of 98.7%, a polymer yield of 97.2%, an anhydride value of 72.0%, a weight average molecular weight of 5600 g / mol, a relative molecular weight distribution index of 1.44, and a particle size D98 of 19 μm.

[0060] Example 7

[0061] The difference from Example 1 is that the amount of maleic anhydride fed is changed to 25% of the total polymerization feed mass, the polymerization ethylene pressure during the polymerization process is changed to 2.5 MPa, the polymerization temperature is changed to 120° C., the polymerization time is changed to 4 h, the initiator is changed to dicumyl peroxide, the molar ratio of dicumyl peroxide to maleic anhydride is changed to 0.015:1, the molecular weight regulator is changed to AMSD, the amount of AMSD is 1% of the mass of maleic anhydride, the feeding time of reaction liquid 1 is changed to 3 h, the feeding time of reaction liquid 2 is changed to 3 h, and the average residence time of the raw material liquid in the reactor in the high-pressure loop reactor is controlled to be 30 min; and the volume ratio of the precipitant n-heptane to acetone in the post-treatment process is 10:1.

[0062] The final narrow molecular weight distribution ethylene-maleic anhydride copolymer product had a maleic anhydride conversion rate of 99.8%, a polymer yield of 98.9%, an anhydride value of 71.0%, a weight average molecular weight of 3200 g / mol, a relative molecular weight distribution index of 1.31, and a particle size D98 of 14 μm.

[0063] Example 8

[0064] The difference from Example 1 is that the amount of maleic anhydride added is changed to 10% of the total polymerization feed mass, and finally an ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution is obtained.

[0065] Example 9

[0066] The difference from Example 1 is that the amount of maleic anhydride added is changed to 40% of the total polymerization feed mass, and finally an ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution is obtained.

[0067] Example 10

[0068] The difference from Example 1 is that the amount of maleic anhydride added is changed to 50% of the total polymerization feed mass, and finally an ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution is obtained.

[0069] Embodiment 11

[0070] The difference from Example 1 is that in the post-treatment process, the volume ratio of the precipitant n-pentane to the solvent methyl acetate used in the polymerization is 1:1; and finally an ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution is obtained.

[0071] Example 12

[0072] The difference from Example 1 is that in the post-treatment process, the volume ratio of the precipitant n-pentane to the polymerization solvent methyl acetate is 15:1; and finally an ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution is obtained.

[0073] Embodiment 13

[0074] The difference from Example 1 is that in the post-treatment process, the volume ratio of the precipitant n-pentane to the polymerization solvent methyl acetate is 20:1; and finally an ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution is obtained.

[0075] Embodiment 14

[0076] The difference from Example 1 is that reaction liquid 1 is pumped into the reactor by metering pump 1 for 30 min, and reaction liquid 2 is pumped into the reactor by metering pump 2 for 30 min, and finally an ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution is obtained.

[0077] Embodiment 15

[0078] The difference from Example 1 is that reaction liquid 1 is pumped into the reactor by metering pump 1 for 10 hours, and reaction liquid 2 is pumped into the reactor by metering pump 2 for 10 hours, and finally an ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution is obtained.

[0079] Example 16

[0080] The difference from Example 1 is that after the polymerization starts, the average residence time of the raw material liquid in the reactor in the high-pressure loop reactor is controlled to be 2 hours, and finally an ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution is obtained.

[0081] Embodiment 17

[0082] The difference from Example 1 is that after the polymerization starts, the average residence time of the raw material liquid in the reactor in the high-pressure loop reactor is controlled to be 4 hours, and finally an ethylene-maleic anhydride copolymer product with a narrow molecular weight distribution is obtained.

[0083] Comparative Example 1

[0084] The difference from Example 1 is that the polymerization reaction is carried out only in the reactor, and the polymerization monomer maleic anhydride, the molecular weight regulator 3-mercaptopropionic acid and the second polymerization solvent acetone solution are mixed to prepare a reaction solution 1 for standby; the initiator benzoyl peroxide and the third polymerization solvent acetone solution are mixed to prepare a reaction solution 2 for standby; wherein the feeding amount of maleic anhydride in the reaction system is 20% of the total polymerization feeding mass, the molar ratio of benzoyl peroxide to maleic anhydride is 0.001:1, the amount of 3-mercaptopropionic acid is 1% of the mass of maleic anhydride, the feeding amount of the second polymerization solvent is 45% of the total polymerization feeding mass, and the feeding amount of the third polymerization solvent is 5% of the total polymerization feeding mass.

[0085] First, the first polymerization solvent acetone solution is introduced into the polymerization reactor, and the feeding amount of the first polymerization solvent is 25% of the total polymerization feeding mass. Then, ethylene is slowly introduced into the polymerization reactor for displacement. After ethylene is introduced until the system ethylene pressure reaches 0.5MPa, the liquid temperature in the reaction system is raised to 90°C, and the liquid temperature in the reactor is maintained unchanged. After the ethylene pressure is gradually supplemented to 3MPa, reaction liquid 1 is pumped into the reactor through metering pump 1 for 4h. At the same time, reaction liquid 2 is pumped into the reactor through metering pump 2 for 4h. The polymerization is started. After the feeding of reaction liquid 1 and reaction liquid 2 is completed, the polymerization reactor continues to be heated and pressurized for 6h, during which the polymerization ethylene pressure is maintained at 3MPa and the polymerization temperature is 90°C.

[0086] After the reaction is completed, the pressure is first released to recover ethylene to the ethylene storage tank, and then the homogeneous product liquid is discharged to the buffer kettle and stirred, and the precipitant n-heptane is added to obtain a polymer precipitate, wherein the volume ratio of n-heptane to acetone is 6:1. The slurry in the buffer kettle after precipitation is then transferred to a centrifugal device, and after centrifugation until the product moisture content is 40%, the wet material is subjected to negative pressure volatilization and drying, the drying temperature is 100°C, the drying pressure is -0.095MPa, and the product moisture content is dried to 0.01%. The acetone and n-heptane solvents obtained by centrifugation and volatilization are reused for the next batch of polymerization reactions after decoking and distillation.

[0087] The final ethylene-maleic anhydride copolymer product had a maleic anhydride conversion rate of 88.1%, a polymer yield of 87.6%, an anhydride value of 72.8%, a weight average molecular weight of 42300 g / mol, a relative molecular weight distribution index of 2.52, and a particle size D98 of 23 μm.

[0088] The anhydride value, particle size D98, weight-average molecular weight and molecular weight distribution of the ethylene-maleic anhydride copolymers obtained in the above embodiments and comparative examples were tested. According to the maleic anhydride monomer content before and after the reaction in the above embodiments and comparative examples and the maleic anhydride content of the ethylene-maleic anhydride copolymer products, and the anhydride value detection of the solvent obtained after centrifugation and evaporation and drying, the conversion rate of maleic anhydride was calculated, and the yield of the ethylene-maleic anhydride copolymer was calculated. The results are shown in Table 1.

[0089] Test method:

[0090] The test method of anhydride value is to dissolve ethylene-maleic anhydride copolymer in water, hydrolyze maleic anhydride into carboxylic acid, and use alkali solution of known concentration to titrate and neutralize to calculate the anhydride content in the sample. The test standard refers to GB / T 2895-2008.

[0091] The testing device for particle size D98 is a laser particle size analyzer, and the testing standard refers to GB / T 19077-2016.

[0092] The testing device for weight average molecular weight and molecular weight distribution is gel permeation chromatography, and the testing standard refers to GB / T21863-2008.

[0093] Table 1

[0094]

[0095]

[0096] From the above description, it can be seen that the above embodiments and comparative examples of the present invention achieve the following technical effects:

[0097] The tubular reactor is quick to heat, has good heat transfer effect, is easy to control temperature, and has stable temperature. It can ensure that the initiator enters the reactor and immediately decomposes to generate free radicals and initiate polymerization, and there is no problem of initiation and decomposition at different times due to temperature gradient. The tubular reactor is convenient for realizing high-speed flow of monomers and polymers in the reactor, and can avoid the problem of polymer adhesion in the reactor due to excessively high reactor wall temperature, which affects heat conduction and polymerization degradation. The present invention carries out polymerization reaction in a tandem reaction system, and constructs a reactor-tube reaction system by combining a tubular reactor with a tank reaction, so that the tandem reaction system has better heat and mass transfer effects. The mixture of the polymerized monomers in the reaction raw materials and the olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution flows in a piston flow manner, so that the back-mixing problem generated when the tank reactor is used for continuous polymerization can be avoided, and the kinetic chain length from free radical self-chain initiation to true kinetic termination is the same or basically similar, and the concentrations of the polymerized monomers, initiators and molecular weight regulators in the reaction can be regulated to obtain ethylene-maleic anhydride copolymer products with a narrow molecular weight distribution. The above method is simple to operate, has mild reaction conditions, low energy consumption and cost, is green and environmentally friendly, and the post-treatment process of the olefin-polymerization monomer alternating copolymer with a narrow molecular weight distribution is simple and easy to separate and purify. The first polymerization solvent and other raw materials can be recycled, and it has good market and industrial prospects.

[0098] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for synthesizing an olefin-polymerized monomer alternating copolymer with a narrow molecular weight distribution, characterized in that: The synthesis method comprises the following steps: Step S1, subjecting the reaction raw materials including a polymerization solvent, an olefin, a polymerization monomer, a molecular weight regulator, and an initiator to a polymerization reaction in a series reaction system to obtain a polymerization reaction product; Step S2, subjecting the raw material including the polymerization product and the precipitant to a precipitation reaction and then to a solid-liquid separation process to obtain an olefin-polymerization monomer alternating copolymer with a narrow molecular weight distribution; Wherein, the polymerizable monomer comprises an active functional group and a carbon-carbon double bond; the olefin is a C2-C6 olefin; The series reaction system comprises a tank reactor and a tubular reactor which are sequentially connected in series.

2. The synthesis method according to claim 1, characterized in that The active functional group is selected from any one or more of a carboxylic acid group, an anhydride group and an amide group, and preferably the polymerizable monomer is selected from any one or more of maleic anhydride, maleic acid, maleimide, itaconic acid and itaconic anhydride; and / or the mass of the polymerizable monomer is 10% to 40% of the total mass of the reaction raw materials.

3. The synthesis method according to claim 1 or 2, characterized in that The olefin is a C2-C4 olefin, and preferably the olefin is ethylene.

4. The synthesis method according to any one of claims 1 to 3, characterized in that The step S2 comprises: Step S21, separating the polymerization reaction product to obtain a homogeneous product liquid and olefins; Step S22, subjecting the raw material including the homogeneous product liquid and the precipitant to a precipitation reaction to obtain a polymer precipitate; Step S23, centrifuging, devolatilizing and drying the polymer precipitate in sequence to obtain the olefin-polymer monomer alternating copolymer with a narrow molecular weight distribution; And / or the narrow molecular weight distribution olefin - polymerized monomer alternating copolymer is preferably an ethylene - maleic anhydride alternating copolymer. The weight average molecular weight of the ethylene-maleic anhydride alternating copolymer is 3000-300000 g / mol, the molecular weight distribution coefficient of the ethylene-maleic anhydride alternating copolymer is less than 2.2, the content of the corresponding molecular chain segment of ethylene in the ethylene-maleic anhydride alternating copolymer is ≤30%, and the content of the corresponding molecular chain segment of maleic anhydride in the ethylene-maleic anhydride alternating copolymer is ≥70%; And / or the moisture content of the polymer precipitate after centrifugation is 30% to 50%.

5. The synthesis method according to claim 4, characterized in that The precipitant is selected from any one or more of n-hexane, ethyl ether, n-heptane, n-pentane or n-butyl ether; and / or the volume ratio of the precipitant to the solvent used for the polymerization is 1:1 to 15:1, preferably 2:1 to 15:

1.

6. The synthesis method according to claim 4, characterized in that The devolatilization drying pressure is -0.085 to -0.098 MPa, and / or the devolatilization drying temperature is 60 to 120° C.; and / or the moisture content of the polymer precipitate after devolatilization drying is 0.01% to 0.05%.

7. The synthesis method according to any one of claims 1 to 6, characterized in that The kettle reactor-tubular reactor comprises a high-pressure reactor, a high-pressure loop reactor and a high-pressure circulation pump connected in series in sequence, and the step S1 comprises: Step S11, firstly introducing the first polymerization solvent into the series reaction system and circulating it through the high-pressure circulation pump, then introducing ethylene to replace the positive pressure of ethylene in the series reaction system to 0.1-0.5 MPa, and maintaining the temperature in the series reaction system at the temperature required for the polymerization reaction, and replenishing ethylene into the series reaction system to the pressure required for the polymerization reaction; Step S12, mixing the raw materials including the second polymerization solvent, the molecular weight regulator and the polymerization monomer to obtain a first reaction solution; Step S13, mixing the raw materials including the initiator and the third polymerization solvent to obtain a second reaction solution; Step S14, adding the first reaction liquid and the second reaction liquid into the autoclave reactor respectively; circulating the reaction raw materials in the high-pressure autoclave and the high-pressure loop reactor by the high-pressure circulation pump and performing the polymerization reaction; Wherein, the amount of the solvent used in the polymerization is the total amount of the first polymerization solvent, the second polymerization solvent and the third polymerization solvent, wherein the amount of the first polymerization solvent is 15% to 30% of the total mass of the reactants, the amount of the second polymerization solvent is 30% to 50% of the total mass of the reactants, and the amount of the third polymerization solvent is 3% to 10% of the total mass of the reactants; and / or the first polymerization solvent, the second polymerization solvent and the third polymerization solvent are each independently selected from any one or more of methyl acetate, acetone, N,N-dimethylformamide and dimethyl sulfoxide; Preferably, the residence time of the reaction raw materials in the high-pressure loop reactor is controlled to be 30 min to 4 h, preferably 30 min to 2 h; Preferably, the first reaction liquid and the second reaction liquid are added to the autoclave reactor independently for 30 min to 10 h, preferably 30 min to 4 h.

8. The synthesis method according to any one of claims 1 to 7, characterized in that In the step S1, the molecular weight regulator is selected from any one or more of 2,4-diphenyl-4-methyl-1-pentene, n-dodecyl mercaptan, 3-mercaptopropionic acid, 2-mercaptoethanol, sodium hypophosphite, sodium formate, sodium pyrosulfite, and sodium bisulfite; preferably, the amount of the molecular weight regulator is 0.01% to 5%, preferably 0.5 to 3%, of the amount of the polymerization monomer.

9. The synthesis method according to any one of claims 1 to 8, characterized in that In the step S1, the molar ratio of the initiator to the polymerization monomer is (0.005-0.015):1, and / or the initiator is an azo compound and / or a peroxide compound, and the azo compound is selected from any one or more of azobisisobutyronitrile, azobisisovaleronitrile, azobisisoheptanenitrile, azobiscyclohexylcarbonitrile and dimethyl azobisisobutyrate; and / or the peroxide compound is selected from any one or more of benzoyl peroxide, dodecyl peroxide, diisopropyl peroxide and diisopropyl peroxydicarbonate.

10. The synthesis method according to any one of claims 1 to 9, characterized in that In the step S1, the polymerization reaction temperature is 55-150° C., and / or the polymerization reaction time is 1-12 h; preferably, the olefin is ethylene, and the ethylene pressure during the polymerization reaction is 2-20 MPa.

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