Low-molecular-weight styrene-maleic anhydride copolymer and continuous flow synthesis process thereof

Abstract

The invention relates to the technical field of preparation of high polymer materials, in particular to a low-molecular-weight styrene-maleic anhydride copolymer and a continuous flow synthesis process thereof.The low-molecular-weight styrene-maleic anhydride copolymer is produced by combining a micro-channel reactor and a tubular reactor; the micro-channel reactor is adopted for feeding and mixing operation, reaction is rapidly carried out in the micro-channel reactor, and then micro-channel reaction materials are introduced into the tubular reactor for curing reaction. Compared with a polymerization process in the prior art, the continuous flow synthesis process provided by the invention can realize continuous production of the styrene-maleic anhydride copolymer with low molecular weight (number-average molecular weight of 2351-6860 g / mol) and narrow distribution (PDI is 1.16-1.8) under mild reaction conditions and low initiator addition amount, the industrial production cost is low, the reaction process is stable, the safety is higher, and the preparation method is suitable for industrial production of the styrene-maleic anhydride copolymer with low molecular weight (number-average molecular weight of 2351-6860 g / mol) and narrow distribution (PDI is 1.16-1.8). And the monomer conversion rate is as high as 98%.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material preparation, and in particular to a low molecular weight styrene maleic anhydride copolymer and a continuous flow synthesis process thereof. Background Art

[0002] Low molecular weight styrene maleic anhydride copolymer has good heat resistance and stability, is easy for secondary processing, has high surface activity and low interfacial tension, and has functions such as dispersion, emulsification, thickening, cross-linking, and flocculation. It is used in coatings, inks, adhesives, textiles, papermaking, building materials, plastics, electronics and other industries. It is a fine chemical with excellent performance and wide application.

[0003] In the prior art, there are many methods for preparing styrene maleic anhydride copolymers. For example, patent CN101503490B discloses a method for synthesizing a low molecular weight styrene / maleic anhydride alternating copolymer. The process uses a four-necked bottle as a reaction vessel to prepare styrene maleic anhydride alternating copolymers at 60-80° C. However, the process uses the principle of precipitation polymerization to prepare styrene maleic anhydride copolymers, which is difficult to form continuous and large-scale industrial production.

[0004] Invention patent CN 111234081 A discloses a low molecular weight narrow distribution styrene-maleic anhydride copolymer and a preparation method thereof, wherein the method uses a tubular reactor with a static mixer as a reaction vessel, performs polymerization reaction at 130°C-300°C to prepare a styrene-maleic anhydride alternating copolymer, and can achieve continuous production. However, the reaction temperature of the method is relatively high, the polymerization reaction is violent and uncontrollable, and the content of maleic anhydride in the prepared copolymer fluctuates greatly, the acid value fluctuates greatly, and the content of styrene autopolymer is high.

[0005] For another example, invention patent CN 113968927 A discloses a method for synthesizing a low molecular weight styrene-maleic anhydride resin using a tubular reactor. In this method, the flow rates of different feed pipelines are controlled so that styrene, maleic anhydride and initiator always react in a specific ratio in the tubular reactor. The reaction temperature is 80°C, the reaction residence time in the tube is 519-545s, and the reaction conversion rate is 93.6%-96.3%. The method is used to prepare a low molecular weight styrene-maleic anhydride resin. The reaction is stable and controllable, but the molecular weight distribution is not ideal, and the PDI is 1.93-2.11. Summary of the invention

[0006] The present invention is made to solve the above problems and aims to provide a continuous flow synthesis process for industrial production of low molecular weight styrene maleic anhydride copolymer.

[0007] The first aspect of the present invention provides a low molecular weight styrene maleic anhydride copolymer continuous flow synthesis process, characterized in that it comprises the following steps: (1) Control the temperature of styrene and maleic anhydride to T1 respectively for standby use; (2) introducing styrene, maleic anhydride and initiator into a microchannel reactor for mixing, so that a portion of the mixture of styrene, maleic anhydride and initiator is a homogeneous fluid at least at one time at the temperature T1, and reacting until the conversion rate of styrene and maleic anhydride is 50% to 70%, thereby obtaining a microchannel reaction material; (3) removing the microchannel reaction material from the microchannel reactor and introducing it into a tubular reactor to continue the reaction at a temperature of T1 until the conversion rate of styrene and maleic anhydride reaches 90% to 100%, thereby obtaining the styrene-maleic anhydride copolymer; The T1 temperature is 80°C-100°C.

[0008] In order to solve the problem of uneven product molecular weight distribution when preparing styrene maleic anhydride copolymer in the prior art, the inventor tried to find the reasons that affect the product molecular weight distribution. It was found that the reactivity ratios of styrene and maleic anhydride copolymers were r1=0.04, r2=0.015, and r1·r2=0.006, respectively. Since the reactivity ratios of both are much less than 1, this means that both monomers are more inclined to react with the active chain ends of heterogeneous monomers. Therefore, the composition of the copolymer prepared using these two monomers may deviate from the initial feed ratio, and the copolymer composition may continue to change as the reaction proceeds, which also leads to the product molecular weight distribution being very easy to be uneven and the PDI being large. Maleic anhydride has a strong electron-withdrawing group, which makes it present a positive polarity, but styrene gives electrons due to the conjugation effect of the benzene ring and becomes a negative polarity. Therefore, the two will form a stable transition state of attraction between positive and negative electrodes during the copolymerization process. If the two monomers are theoretically evenly mixed in a certain proportion, an alternating copolymer can be obtained, which is expected to reduce the PDI of the product. Therefore, during the reaction, the higher the mixing efficiency of the two monomers and the more uniform the mixing of the initiator, the more conducive it is to improving the molecular weight distribution of the product.

[0009] In the prior art, since the inner diameter of the microchannel reactor is small and the viscosity of the polymer product is large, it is easy to cause the microchannel reactor to be blocked, and the microchannel reactor is generally not used for polymerization. Even if a microchannel reactor is used for reaction, it will be unfavorable for industrial production due to the high reaction temperature. For example, patent CN113234308A mentions the polymerization experiment of methyl methacrylate and glycidyl methacrylate using a microchannel reactor. In this technical solution, in order to increase the fluidity of the polymer and avoid blocking the microchannel reactor, the reaction temperature is as high as 140°C. Not only is the reaction temperature high, but the amount of initiator added is as high as 5% of the total mass of the polymerized monomer, resulting in high production costs, which is not conducive to industrial production.

[0010] Furthermore, since the liquid holding capacity of the microchannel reactor is extremely small, it is usually used for small-scale or laboratory-scale reactions and cannot be used for industrial-scale copolymer production. Once the reaction system is too large, it is not only easy to cause blockage, but also requires a large number of microchannel reactors to be used in series, and the instrument cost is high. Therefore, in the prior art, at T1 temperature (80°C-100°C), a reactor with a large inner diameter is usually used as a reaction container. For example, patent CN101503490B uses a four-necked bottle as a reaction container to prepare styrene maleic anhydride alternating copolymers at 60~80°C; patent CN 113968927 A uses a tubular reactor for reaction at a reaction temperature of 80°C.

[0011] The present invention uses a microchannel reactor and a tubular reactor in series, and does not complete the entire polymerization reaction in the microchannel reactor. It only utilizes the characteristics of the microchannel reactor to achieve mixing and partial reaction of polymerization monomers and initiators. When styrene, maleic anhydride and initiator are introduced into the microchannel reactor, the mixture of styrene, maleic anhydride and initiator will continuously and strongly collide with the inner wall of the microchannel, and generate strong secondary flow, multiple vortexes and reverse collisions inside the mixture, so that part of the mixture of styrene, maleic anhydride and initiator is a homogeneous fluid at least at one moment at the temperature T1, and the mixture flows continuously inside the microchannel reactor. Therefore, the homogeneous fluid of the first-formed mixture of part of styrene, maleic anhydride and initiator will continuously mix with the remaining mixture, so that more mixture forms a homogeneous fluid of a larger volume, thereby achieving rapid and uniform mixing of all the mixtures, and the uniformly mixed mixture will react quickly to obtain styrene maleic anhydride copolymer. Therefore, the mixture of styrene, maleic anhydride and initiator is continuously reacting during the flow inside the microchannel reactor. When the mixture leaves the microchannel reactor, the conversion rate of styrene and maleic anhydride can reach 50%~70%, and a microchannel reaction material is obtained.

[0012] Furthermore, in order to prevent clogging of the microchannel reactor, the present invention pre-treats styrene and maleic anhydride. Before the reaction, the raw materials (styrene, maleic anhydride) are respectively temperature-controlled to T1 temperature. On the one hand, the temperature increase can reduce the viscosity of the two and improve the mixing efficiency of the two in the microchannel reactor. On the other hand, the temperature increase allows the two to reach the required reaction temperature before entering the microchannel reactor, thereby ensuring that the two can react quickly when mixed in the microchannel reactor, accelerating the reaction rate, thereby shortening the reaction time required for the raw materials in the microchannel reactor, thereby reducing the scale of the required microchannel reactor, shortening the reaction path of the raw materials in the microchannel reactor, and reducing the possibility of clogging.

[0013] Furthermore, as the styrene maleic anhydride copolymer is continuously produced, the viscosity of the mixture will continue to increase. In order to prevent the viscosity of the mixture from being too high and causing precipitation, thereby clogging the microchannel reactor, when the conversion rate of styrene and maleic anhydride reaches 50% to 70%, the mixture is collected to obtain a microchannel reaction material, and the microchannel reaction material is moved out of the microchannel reactor and transferred to a tubular reactor to continue producing styrene maleic anhydride copolymer.

[0014] The continuous flow synthesis process of the present invention combines a microchannel reactor and a tubular reactor to produce a low molecular weight styrene maleic anhydride copolymer. The raw materials are pretreated first, and then the microchannel reactor is used to perform feeding and mixing operations, and a rapid reaction is performed in the microchannel reactor. Then, the microchannel reaction materials are introduced into the tubular reactor for a aging reaction.

[0015] Compared with the polymerization process in the prior art, the process of the present invention adopts a microchannel reactor as a container for rapid reaction, which has the advantages of fast heat transfer and high mixing efficiency, and further adopts a tubular reactor as a container for aging reaction, which has the advantages of high efficiency and high production capacity. Therefore, the continuous flow synthesis process of the present invention can realize continuous production of styrene maleic anhydride copolymers with low molecular weight (number average molecular weight of 2351-6860 g / mol) and narrow distribution (PDI of 1.16-1.8) under mild reaction conditions and low initiator addition amount, and the reaction process is stable, has higher safety, and the monomer conversion rate is as high as 98%.

[0016] In some embodiments, in step (2), the initiator includes a primary initiator and a secondary initiator, and step (2) specifically includes: pumping styrene, maleic anhydride, and the primary initiator into the microchannel reactor simultaneously for preliminary mixing, until a mixture of part of styrene, maleic anhydride, and the initiator is a homogeneous fluid at least at one moment at the temperature T1, and then pumping in the secondary initiator for secondary mixing.

[0017] Compared with the prior art, the present invention divides the entire polymerization process into three stages for reaction. In the first stage, styrene, maleic anhydride, and the primary initiator are preliminarily mixed and reacted in a microchannel reactor; in the second stage, styrene, maleic anhydride, the primary initiator, and the pumped secondary initiator are secondary mixed and reacted in the microchannel reactor; in the third stage, the uniformly mixed styrene, maleic anhydride, the primary initiator, and the secondary initiator are subjected to a aging reaction in a tubular reactor. The present invention adds the initiator in steps so that the initiator and the raw materials can be more fully mixed, thereby controlling the reaction rate and reaction degree in each stage respectively to improve the stability and safety of the reaction, thereby maximizing the use of the initiator and improving the conversion rate of the monomer without increasing or even reducing the amount of the initiator.

[0018] At the same time, in the embodiment, the initiator is divided into a main initiator and a secondary initiator, and mixed with the raw materials in batches. The raw materials and the main initiator are first preliminarily mixed to react, and after the reaction is stable, the secondary initiator is pumped into the microchannel reactor in the later process to further initiate the reaction, so as to control the polymerization rate of the polymerization reaction and improve the safety of the process system. Compared with the prior art of adding all the initiators at one time, it can prevent the polymerization reaction rate from being too fast, the temperature of the reaction system from rising sharply, the reaction from being too violent, and even causing safety hazards such as explosion.

[0019] Experimental tests have shown that when styrene, maleic anhydride and primary initiator are simultaneously pumped into a microchannel reactor for preliminary mixing for 0.1 to 10 minutes, it can be ensured that a portion of the mixture of styrene, maleic anhydride and initiator in the microchannel reactor is a homogeneous fluid at least at the temperature T1. At this time, a secondary initiator is pumped in for secondary mixing to further initiate the reaction.

[0020] In some embodiments, in step (2), the mass of the initiator is 1%-1.5% of the sum of the mass of styrene and maleic anhydride. The present invention improves the utilization rate of the initiator through ingenious experimental design. Therefore, in the embodiment, only 1%-1.5% of the sum of the mass of styrene and maleic anhydride is needed to achieve a reaction conversion rate of 98%. Compared with the prior art, the initiator content is lower and the effect is significant.

[0021] In some embodiments, in step (2), the mass ratio of the secondary initiator to the primary initiator is 1:(1-3). In the embodiment, the mass of the primary initiator needs to be greater than the mass of the secondary initiator. In the first stage, the raw materials and the primary initiator are rapidly mixed and reacted in the first half of the microchannel reactor. When the mixture reaches the second half of the microchannel reactor, the intensity of the polymerization reaction gradually decreases. The secondary initiator is then added, and after further mixing and initiating the reaction in the second stage, the mixed product is passed into the tubular reactor and enters the third stage for aging reaction.

[0022] In some embodiments, in step (2), the initiator includes at least one of azobisisoheptanonitrile, azobisisobutyronitrile, dimethyl azobisisobutyrate, azobisisobutyronitrile, and benzoyl peroxide. In the embodiments, the reaction conditions required by the above initiators are mild, and the polymerization reaction initiated by them is relatively fast, which can further shorten the reaction time, improve production efficiency, and reduce the possibility of blockage.

[0023] In some embodiments, the step (2) specifically includes: connecting a high-pressure constant-flow metering pump to the feed port of the microchannel reactor, connecting the discharge port of the microchannel reactor to the feed port of the tubular reactor, dissolving styrene, maleic anhydride, the primary initiator, and the secondary initiator in the solvent respectively, and then pumping them into the microchannel reactor using a high-pressure constant-flow metering pump.

[0024] In some embodiments, the solvent includes one of ethylene glycol ethyl ether acetate, butanone, ethyl butyrate, and toluene.

[0025] In some embodiments, in step (3), the reaction time is controlled within a range of 50 min to 90 min.

[0026] In the embodiment, the mixed product fully mixed in the microchannel reactor needs to be aged in a tubular reactor, especially to allow the remaining raw materials and the secondary initiator added during the secondary mixing to have sufficient time to fully react, thereby improving the conversion rate of the monomers.

[0027] In some embodiments, the mass ratio of styrene to maleic anhydride is (1-4):1.

[0028] The second aspect of the present invention provides a low molecular weight styrene maleic anhydride copolymer, characterized in that the styrene maleic anhydride copolymer is prepared according to the styrene maleic anhydride copolymer continuous flow synthesis process described in any one of the first aspects, and the number average molecular weight of the styrene maleic anhydride copolymer is 2000g / mol-7000g / mol, and the molecular weight distribution PDI is 1.1-1.8.

[0029] By implementing the above technical solution, the present invention has the following beneficial effects: The continuous flow synthesis process of the present invention combines a microchannel reactor and a tubular reactor to produce a low molecular weight styrene maleic anhydride copolymer. The raw materials are pretreated first, and then the microchannel reactor is used to perform feeding and mixing operations, and the reaction is quickly carried out in the microchannel reactor. Then, the microchannel reaction materials are introduced into the tubular reactor for aging reaction.

[0030] Compared with the polymerization process in the prior art, the process of the present invention adopts a microchannel reactor as a container for rapid reaction, which has the advantages of fast heat transfer and high mixing efficiency, and further adopts a tubular reactor as a container for aging reaction, which has the advantages of high efficiency and high production capacity. Therefore, the continuous flow synthesis process of the present invention can realize continuous production of styrene maleic anhydride copolymers with low molecular weight (number average molecular weight of 2351-6860 g / mol) and narrow distribution (PDI of 1.16-1.8) under mild reaction conditions (reaction temperature of 80-100° C.) and low initiator addition amount (the mass of the required initiator is only 1%-1.5% of the total mass of polymer monomers), and the cost of industrial production is low, the reaction process is stable, the process has higher safety, and the monomer conversion rate is as high as 98%.

[0031] Compared with the prior art, the present invention adds the initiator in steps so that the initiator and the raw materials can be mixed more fully, thereby controlling the reaction rate and reaction degree in each stage respectively to improve the stability and safety of the reaction, thereby maximizing the utilization of the initiator and improving the conversion rate of the monomer without increasing or even reducing the amount of initiator used. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 is the infrared spectrum of the styrene maleic anhydride copolymer in Example 1 of the present invention; Figure 2 is a polarizing microscope image of the styrene maleic anhydride copolymer in Example 2 of the present invention; Figure 3 It is the gel chromatography molecular weight test result of SARTOMER™ SMA1000P; Figure 4 This is the gel chromatography molecular weight test result of the styrene maleic anhydride copolymer in Example 1. DETAILED DESCRIPTION

[0033] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is described in detail below in conjunction with embodiments and drawings.

[0034] Example 1 Reaction device: Tesla channel microchannel reactor, single-chip size 225×170mm, material silicon carbide, single-chip liquid holding capacity / reaction volume is 50ml, maximum flux 20kg / hour, using 5 microchannel reactors in series integration; 4 high-pressure constant-current metering pumps, double-plunger parallel flow mode, flow range 20ml~500ml / min, increment 0.1ml / min, maximum pressure 10MPa, high-pressure constant-current metering pump, double-plunger parallel flow mode, flow range 30ml~1000ml / min; horizontal tubular reactor, material 316L stainless steel pipe, pipe inner diameter 2.1cm; temperature control system, 2 sets of explosion-proof mold temperature machine cooling and heating integrated machines, respectively control the temperature of the microchannel reactor and the horizontal tubular reactor, -25℃~200℃, temperature control accuracy ±0.5℃.

[0035] Connection relationship of the reaction devices: the discharge ports of three high-pressure constant-current metering pumps respectively connected to material tank A, material tank B and material tank C are connected to the feed port of the first microchannel reactor by a multi-way valve, the discharge port of the first microchannel reactor is connected to the feed port of the second microchannel reactor, the discharge port of the second microchannel reactor is connected to the feed port of the third microchannel reactor, the third and fourth microchannel reactors are connected in series in sequence, the feed port of the fifth microchannel reactor is connected to the discharge port of a high-pressure constant-current metering pump connected to material tank D and the discharge port of the fourth microchannel reactor by a three-way valve, and the discharge port of the fifth microchannel reactor is quickly connected to the feed port of the horizontal tubular reactor.

[0036] Material preparation: In material tank A, 2083 grams of styrene monomer and 4000 grams of ethylene glycol ethyl ether acetate are mixed and heated to 80°C as component one; in material tank B, 1960 grams of maleic anhydride are dissolved in 4750 grams of ethylene glycol ethyl ether acetate and heated to 80°C as component two; in material tank C, 37.7 grams of azobisisoheptanenitrile are dissolved in 2000 grams of ethylene glycol ethyl ether acetate solvent as component three; in material tank D, 15 grams of benzoyl peroxide are dissolved in 1000 grams of ethylene glycol ethyl ether acetate as component four.

[0037] Component 1 of material tank A was pumped into the first microchannel reactor at a flow rate of 304.15 ml / min, component 2 of material tank B was pumped into the first microchannel reactor at a flow rate of 335.5 ml / min, and component 3 of material tank C was pumped into the first microchannel reactor at a flow rate of 101.88 ml, and the reaction temperature was controlled at 80°C. Components 1, 2 and 3 were contacted at the feed port of the first microchannel reactor, and simultaneously entered the first microchannel reactor for mixing, and flowed into other microchannel reactors in series. After 2 minutes, component 4 of material tank D was pumped into the fifth microchannel reactor at a flow rate of 50.75 ml / min. Component 4 was contacted with components 1, 2 and 3 at the feed port of the fifth microchannel reactor, and mixed in the fifth microchannel reactor. After microchannel reaction, samples were taken at the discharge port and gas chromatography was used to monitor the conversion rate of styrene and maleic anhydride to reach 50%~70%, and microchannel reaction materials were obtained. The microchannel reaction materials were pumped into a horizontal tubular reactor, and the temperature was maintained at 80°C to continue the reaction. The reaction residence time in the horizontal tubular reactor was 60 minutes. The reaction product was desolventized by vacuum rotary scraper film process to obtain white powder. The total yield of the product was about 98.0%, the number average molecular weight was 2351 g / mol, and the molecular weight distribution PDI was 1.16.

[0038] Example 2 Reaction device: core-type channel microchannel reactor, single-piece size 225×170mm, material silicon carbide, single-piece liquid holding capacity / reaction volume is 50ml, maximum flux 20kg / hour, using 5 microchannel reactors in series integration; 4 high-pressure constant-current metering pumps, double-plunger parallel flow mode, flow range 20ml~500ml / min, increment 0.1ml / min, maximum pressure 10MPa, high-pressure constant-current metering pump, double-plunger parallel flow mode, flow range 30ml~1000ml / min; horizontal tubular reactor, material 316L stainless steel pipe, pipe inner diameter 2.1cm, feed inlet and microchannel reactor outlet quick connection; temperature control system, 2 sets of explosion-proof mold temperature machine cooling and heating integrated machine, respectively control the temperature of the microchannel reactor and the horizontal tubular reactor, -25℃~200℃, temperature control accuracy ±0.5℃.

[0039] Connection relationship of the reaction devices: the discharge ports of three high-pressure constant-current metering pumps respectively connected to material tank A, material tank B and material tank C are connected to the feed port of the first microchannel reactor by a multi-way valve, the discharge port of the first microchannel reactor is connected to the feed port of the second microchannel reactor, the discharge port of the second microchannel reactor is connected to the feed port of the third microchannel reactor, the third and fourth microchannel reactors are connected in series in sequence, the feed port of the fifth microchannel reactor is connected to the discharge port of a high-pressure constant-current metering pump connected to material tank D and the discharge port of the fourth microchannel reactor by a three-way valve, and the discharge port of the fifth microchannel reactor is quickly connected to the feed port of the horizontal tubular reactor.

[0040] Material preparation: In material tank A, 2770.4 grams of styrene monomer and 4000 grams of butanone are mixed and heated to 100°C as component one; in material tank B, 1304.2 grams of maleic anhydride are dissolved in 4750 grams of butanone and heated to 100°C as component two; in material tank C, 37.7 grams of azobisisobutyronitrile are dissolved in 2000 grams of butanone solvent as component three; in material tank D, 15 grams of benzoyl peroxide are dissolved in 1000 grams of butanone as component four.

[0041] Component 1 of A material tank is pumped into the first microchannel reactor at a flow rate of 338.52ml / min, component 2 of B material tank is pumped into the first microchannel reactor at a flow rate of 302.71ml / min, and component 3 of C material tank is pumped into the first microchannel reactor at a flow rate of 101.88ml, and the reaction temperature is controlled at 100℃. Components 1, 2 and 3 are contacted at the feed port of the first microchannel reactor, and enter the first microchannel reactor at the same time for mixing, and flow into other microchannel reactors in series. After 2 minutes, component 4 of D material tank is pumped into the fifth microchannel reactor at a flow rate of 50.75ml / min. Component 4 contacts with components 1, 2 and 3 at the feed port of the fifth microchannel reactor, and mixes in the fifth microchannel reactor. After microchannel reaction, sampling is taken at the discharge port and gas chromatography is used to monitor the conversion rate of styrene and maleic anhydride to reach 50%~70%, and microchannel reaction materials are obtained. The microchannel reaction materials are pumped into a horizontal tubular reactor, and the temperature is maintained at 100℃ to continue the reaction. The reaction residence time in the horizontal tubular reactor is 60 minutes. The reaction product was desolventized by vacuum rotary scraper film process to obtain white powder. The total yield of the product was about 97.0%, the number average molecular weight was 4821 g / mol, and the molecular weight distribution PDI was 1.49.

[0042] Example 3 Reaction device: Octopus channel microchannel reactor, single-chip size 225×170mm, material silicon carbide, single-chip liquid holding capacity / reaction volume is 50ml, maximum flux 20kg / hour, using 5 microchannel reactors in series integration; 4 high-pressure constant-current metering pumps, double-plunger parallel flow mode, flow range 20ml~500ml / min, increment 0.1ml / min, maximum pressure 10MPa, high-pressure constant-current metering pump, double-plunger parallel flow mode, flow range 30ml~1000ml / min; horizontal tubular reactor, material 316L stainless steel pipe, pipe inner diameter 2.1cm, feed port and microchannel reactor outlet quick connection; temperature control system, 2 sets of explosion-proof mold temperature machine cooling and heating integrated machine, respectively control the temperature of the microchannel reactor and the horizontal tubular reactor, -25℃~200℃, temperature control accuracy ±0.5℃.

[0043] Connection relationship of the reaction devices: the discharge ports of three high-pressure constant-current metering pumps respectively connected to material tank A, material tank B and material tank C are connected to the feed port of the first microchannel reactor by a multi-way valve, the discharge port of the first microchannel reactor is connected to the feed port of the second microchannel reactor, the discharge port of the second microchannel reactor is connected to the feed port of the third microchannel reactor, the third and fourth microchannel reactors are connected in series in sequence, the feed port of the fifth microchannel reactor is connected to the discharge port of a high-pressure constant-current metering pump connected to material tank D and the discharge port of the fourth microchannel reactor by a three-way valve, and the discharge port of the fifth microchannel reactor is quickly connected to the feed port of the horizontal tubular reactor.

[0044] Material preparation: In material tank A, 4166 grams of styrene monomer and 6000 grams of ethyl butyrate are mixed and heated to 90°C as component one; in material tank B, 980 grams of maleic anhydride are dissolved in 2750 grams of ethyl butyrate and heated to 90°C as component two; in material tank C, 37.7 grams of dimethyl azobisisobutyrate is dissolved in 2000 grams of ethyl butyrate solvent as component three; in material tank D, 15 grams of azobisisobutyronitrile is dissolved in 1000 grams of ethyl butyrate as component four.

[0045] Component 1 of A material tank is pumped into the first microchannel reactor at a flow rate of 508.3ml / min, component 2 of B material tank is pumped into the first microchannel reactor at a flow rate of 186.5ml / min, and component 3 of C material tank is pumped into the first microchannel reactor at a flow rate of 101.88ml, and the reaction temperature is controlled at 90°C. Components 1, 2 and 3 are contacted at the feed port of the first microchannel reactor, and enter the first microchannel reactor at the same time for mixing, and flow into other microchannel reactors in series. After 2 minutes, component 4 of D material tank is pumped into the fifth microchannel reactor at a flow rate of 50.75ml / min. Component 4 contacts with components 1, 2 and 3 at the feed port of the fifth microchannel reactor, and mixes in the fifth microchannel reactor. After microchannel reaction, sampling is taken at the discharge port and gas chromatography is used to monitor the conversion rate of styrene and maleic anhydride to reach 50%~70%, and microchannel reaction materials are obtained. The microchannel reaction materials are pumped into a horizontal tubular reactor, and the temperature is maintained at 90°C to continue the reaction. The reaction residence time in the horizontal tubular reactor is 60 minutes. The reaction product was desolventized by vacuum rotary scraper film process to obtain white powder. The total yield of the product was about 96.0%, the number average molecular weight was 6860 g / mol, and the molecular weight distribution PDI was 1.8.

[0046] Comparative Example 1 This comparative example was experimented with reference to the technical solution of patent CN 101503490 B, and the specific experimental steps are as follows: In a 250ml four-necked flask equipped with an electric stirrer, a thermometer and a reflux condenser, add 150ml toluene, 10.4g (0.10mol) styrene, 9.8g (0.10mol) maleic anhydride and 0.1g dibenzoyl peroxide. Heat to about 50℃, stir for 15 min, and dissolve the maleic anhydride completely. Then, heat to about 80℃ and react for 1 h. During the reaction, the product gradually precipitates and the reactant gradually thickens. Stop heating when stirring becomes difficult. Cool the reactant to room temperature, filter out the product, and dry it in vacuum at 60℃. The total yield of the product is about 96.0%, the number average molecular weight is 10500g / mol, and the molecular weight distribution PDI is 1.8.

[0047] Comparative Example 2 This comparative example was tested with reference to Example 1. The difference from Example 1 is that no secondary initiator was added in this comparative example. The specific experimental steps are as follows: Reaction device: Tesla channel microchannel reactor, single-chip size 225×170mm, material silicon carbide, single-chip liquid holding capacity / reaction volume is 50ml, maximum flux 20kg / hour, using 5 microchannel reactors in series integration; 3 high-pressure constant-current metering pumps, double-plunger parallel flow mode, flow range 20ml~500ml / min, increment 0.1ml / min, maximum pressure 10MPa, high-pressure constant-current metering pump, double-plunger parallel flow mode, flow range 30ml~1000ml / min; horizontal tubular reactor, material 316L stainless steel pipe, pipe inner diameter 2.1cm; temperature control system, 2 sets of explosion-proof mold temperature machine cooling and heating integrated machines, respectively control the temperature of the microchannel reactor and the horizontal tubular reactor, -25℃~200℃, temperature control accuracy ±0.5℃.

[0048] Connection relationship of the reaction devices: the discharge ports of the three high-pressure constant-current metering pumps respectively connected to the A material tank, the B material tank and the C material tank are connected to the feed port of the first microchannel reactor by a multi-way valve, the discharge port of the first microchannel reactor is connected to the feed port of the second microchannel reactor, the discharge port of the second microchannel reactor is connected to the feed port of the third microchannel reactor, the third, fourth and fifth microchannel reactors are connected in series in sequence, and the discharge port of the fifth microchannel reactor is quickly connected to the feed port of the horizontal tubular reactor.

[0049] Material preparation: In material tank A, 2083 grams of styrene monomer and 4000 grams of ethylene glycol ethyl ether acetate are mixed and heated to 80°C as component one; in material tank B, 1960 grams of maleic anhydride are dissolved in 4750 grams of ethylene glycol ethyl ether acetate and heated to 80°C as component two; in material tank C, 37.7 grams of azobisisoheptanenitrile are dissolved in 2000 grams of ethylene glycol ethyl ether acetate solvent as component three.

[0050] The A material tank component 1 is pumped into the first core-shaped microchannel reactor at a flow rate of 304.15ml / min, the B material tank component 2 is pumped into the first core-shaped microchannel reactor at a flow rate of 335.5ml / min, and the C material tank component 3 is pumped into the first core-shaped microchannel reactor at a flow rate of 101.88ml, and the reaction temperature is controlled at 80°C. Components 1, 2, and 3 are contacted at the feed port of the first microchannel reactor, and simultaneously enter the first microchannel reactor for mixing, and flow into other microchannel reactors in series, and after microchannel reaction, they are pumped into the horizontal tubular reactor together, and the reaction residence time in the horizontal tubular reactor is 600s. The reaction product is collected and the solvent is removed by a vacuum rotary scraper film process to obtain a white powder. The total yield of the product is measured to be about 65.0%, the number average molecular weight is 1100g / mol, and the molecular weight distribution PDI is 1.3.

[0051] Comparative Example 3 This comparative example was experimented with reference to the technical solution of patent CN 113968927A, and the specific experimental steps are as follows: Test device: horizontal tubular reactor, made of 316L stainless steel pipe, with an inner diameter of 2.1cm; high-pressure constant-flow metering pump, double-plunger parallel flow mode, flow range 30ml~1000ml / min; temperature control system, 2 sets of explosion-proof mold temperature machine cooling and heating integrated machine, -25℃~200℃, temperature control accuracy ±0.5℃.

[0052] 1164g of maleic anhydride, 94.5g of azobisisobutyronitrile and 1800g of butanone were prepared as component A; 1234.5g of styrene, 25.5g of azobisisobutyronitrile and 1800g of butanone were prepared as component B; high-pressure constant-current metering pumps were used to feed component A and component B into a tubular reactor at a speed of 330mL / min, the polymerization temperature was controlled at 80°C, the reaction residence time was 545s, and the reaction product was desolventized by a vacuum rotary scraper film process to obtain a white powder. The total yield of the product was measured to be about 90.0%, the number average molecular weight was 4300g / mol, and the molecular weight distribution PDI was 1.9.

[0053] Comparative Example 4 This comparative example was experimented with reference to comparative example 1. The difference from comparative example 1 was that in this comparative example, the amount of raw materials used was: 13.6 g styrene, 6.6 g maleic anhydride, the reaction temperature was 100°C, and the total yield of the product was measured to be about 90.0%, the number average molecular weight was 6630 g / mol, and the molecular weight distribution PDI was 2.1.

[0054] Comparative Example 5 This comparative example was experimented with reference to comparative example 2. The difference from comparative example 2 was that in this comparative example, the amount of raw materials used was: 2695 g styrene, 1350 g maleic anhydride, the reaction temperature was 100°C, and the total yield of the product was measured to be about 60.0%, the number average molecular weight was 4880 g / mol, and the molecular weight distribution PDI was 1.5.

[0055] Comparative Example 6 This comparative example was experimented with reference to comparative example 3. The difference from comparative example 3 is that in this comparative example, the amount of raw materials used is: 1600 g styrene, 800 g maleic anhydride, the reaction temperature is 100°C, and the total yield of the product is measured to be about 60.0%, the number average molecular weight is 4880 g / mol, and the molecular weight distribution PDI is 1.5.

[0056] Comparative Example 7 This comparative example was experimented with reference to comparative example 1. The difference from comparative example 1 was that in this comparative example, the amount of raw materials used was: 16.0 g styrene, 4.0 g maleic anhydride, the reaction temperature was 90°C, and the total yield of the product was measured to be about 86.0%, the number average molecular weight was 8960 g / mol, and the molecular weight distribution PDI was 2.3.

[0057] Comparative Example 8 This comparative example was experimented with reference to comparative example 2. The difference from comparative example 2 was that in this comparative example, the amount of raw materials used was: 3235 g styrene, 810 g maleic anhydride, the reaction temperature was 90°C, and the total yield of the product was measured to be about 62.0%, the number average molecular weight was 7150 g / mol, and the molecular weight distribution PDI was 1.9.

[0058] Comparative Example 9 This comparative example was experimented with reference to comparative example 3. The difference from comparative example 3 was that in this comparative example, the amount of raw materials used was: 1920 g styrene, 480 g maleic anhydride, the reaction temperature was 90°C, and the total yield of the product was measured to be about 65.0%, the number average molecular weight was 8210 g / mol, and the molecular weight distribution PDI was 2.1.

[0059] Comparative Example 10 This comparative example is selected from Example 1 of patent CN 113968927A, and the specific contents are as follows: Add 77.6g of maleic anhydride, 6.3g of azobisisobutyronitrile and 120g of butanone to the first batching tank to prepare reaction solution A; add 82.3g of styrene, 1.7g of azobisisobutyronitrile and 120g of butanone to the second batching tank to prepare reaction solution B; keep the polymerization monomer mixed solution at 10°C. Nitrogen was introduced into the first batching tank and the second batching tank for 40 minutes respectively to remove the oxygen mixed in the monomer mixed solution, and the oxygen mass was controlled to be below 2ppm. The materials were fed into the tubular reactor at a speed of 22mL / min through the first raw material pump and the second raw material pump respectively. The system pressure was monitored by the first pressure gauge and the second pressure gauge during the whole process, and the pipeline pressure was adjusted to 2MPa by the back pressure valve. The polymerization temperature in the tubular reactor was controlled to 80°C by the oil bath 8, and the reaction residence time was 545s. After the reaction product passes through the cooling coil ice water bath, it flows out of the reactor in a continuous flow state. The reaction liquid is collected in the product collection tank and dried to obtain a colorless and transparent polymer. The total yield of the product is measured to be about 96.5%, the number average molecular weight is 4345g / mol, and the molecular weight distribution PDI is 1.91.

[0060] Comparative Example 11 This comparative example is selected from Example 2 of patent CN 113968927A, and the specific contents are as follows: Add 51.7g of maleic anhydride, 2.67g of azobisisobutyronitrile and 80g of butanone to the first batching tank to prepare reaction solution A; add 109.8g of styrene, 5.33g of azobisisobutyronitrile and 160g of butanone to the second batching tank to prepare reaction solution B; keep the polymerization monomer mixed solution at 10°C. Nitrogen was introduced into the first batching tank and the second batching tank for 40min respectively, and the oxygen mass was controlled to be below 2ppm. Reaction solution A and reaction solution B were respectively sent to the tubular reactor by the first raw material pump and the second raw material pump at a speed of 14.5mL / min and 29mL / min. The system pressure was monitored by the first pressure gauge and the second pressure gauge during the whole process, and the pipeline pressure was adjusted to 2.2MPa by the back pressure valve. The polymerization temperature in the tubular reactor was controlled to 80°C by the oil bath pot, and the reaction residence time was 537s. After the reaction product passes through the cooling coil ice water bath, it flows out of the reactor in a continuous flow state. The reaction liquid is collected in a product collection tank and dried to obtain a colorless and transparent polymer. The total yield of the product is measured to be about 95.3%, the number average molecular weight is 5927g / mol, and the molecular weight distribution PDI is 1.83.

[0061] Comparative Example 12 This comparative example is selected from Example 4 of patent CN 113968927A, and the specific contents are as follows: Add 31.1g of maleic anhydride, 1.6g of azobisisobutyronitrile and 48g of butanone to the first batching tank to prepare reaction solution A; add 132g of styrene, 6.4g of azobisisobutyronitrile and 192g of butanone to the second batching tank to prepare reaction solution B; keep the polymerization monomer mixed solution at 10°C. Nitrogen was introduced into the first batching tank and the second batching tank for 40min respectively, and the oxygen mass was controlled to be below 2ppm. Reaction solution A and reaction solution B were respectively sent to the tubular reactor by the first raw material pump and the second raw material pump 4 at a speed of 8.7mL / min and 35.6mL / min. The system pressure was monitored by the first pressure gauge and the second pressure gauge during the whole process, and the pipeline pressure was adjusted to 2.5MPa by the back pressure valve. The polymerization temperature in the tubular reactor was controlled to 80°C by the oil bath pot, and the reaction residence time was 521s.

[0062] After the reaction product passes through the cooling coil ice water bath, it flows out of the reactor in a continuous flow state. The reaction liquid is collected in a product collection tank and dried to obtain a colorless and transparent polymer. The total yield of the product is measured to be about 94.1%, the number average molecular weight is 7850g / mol, and the molecular weight distribution PDI is 1.95.

[0063] Comparative Example 13 This comparative example is selected from Example 11 of patent CN 111234081A, and the specific contents are as follows: Material ratio: 30 kg of solvent cyclohexanone, accounting for 30% of the total mass of all materials; the molar ratio of monomer maleic anhydride to styrene is 1:1, maleic anhydride 33.9 kg, styrene 36.1 kg; initiator azobisisobutyronitrile 0.7 kg, accounting for 1% of the total mass of maleic anhydride and styrene.

[0064] Preparation of copolymer: add styrene, maleic anhydride, initiator and reaction solvent into a monomer mixing reactor, exhaust air with nitrogen and stir and mix until maleic anhydride is dissolved, then use a feed pump to uniformly send the obtained mixture to a tubular reactor at 240°C, the residence time of the mixture is 10 minutes, and the obtained reaction material is sent to a devolatilizer for devolatilization to obtain a low molecular weight narrow distribution styrene-maleic anhydride copolymer and a degassing material; after the low molecular weight narrow distribution styrene-maleic anhydride copolymer obtained by devolatilization is discharged through a melt pump, granulated and packaged to obtain a finished product; the degassing material obtained by devolatilization is condensed and recovered in a condensation system, the obtained recycled material is stored in a recovered monomer storage tank, distilled, and the obtained material is reused in a polymerization reaction. The total yield of the product is measured to be about 96.0%, the number average molecular weight is 4421g / mol, and the molecular weight distribution PDI is 1.25.

[0065] Data comparison and analysis According to the above examples 1-3 and comparative examples 1-13, tests and data analysis were performed, and the finished products SARTOMER™ SMA1000P, SARTOMER™ SMA2000P and SARTOMER™ SMA4000P on the market were compared. The results are shown in Table 1: Table 1 Test results of examples and comparative examples sample Monomer ratio Initiator (%) Reaction temperature (℃) Reaction conversion rate (%) Number average molecular weight (g / mol) PDI Example 1 1:1 1.30 80 98.0 2351 1.16 Example 2 2:1 1.29 100 97.0 4821 1.49 Example 3 4:1 1.02 90 96.0 6860 1.8 Comparative Example 1 1:1 0.50 80 96.0 10500 1.8 Comparative Example 2 1:1 0.93 80 65.0 1100 1.3 Comparative Example 3 1:1 5.00 80 90.0 4300 1.9 Comparative Example 4 2:1 0.50 100 90.0 6630 2.1 Comparative Example 5 2:1 0.93 100 60.0 4880 1.5 Comparative Example 6 2:1 1.06 100 80.0 5640 2.0 Comparative Example 7 4:1 0.50 90 86.0 8960 2.3 Comparative Example 8 4:1 0.93 90 62.0 7150 1.9 Comparative Example 9 4:1 1.06 90 65.0 8210 2.1 Comparative Example 10 1:1 5.00 80 96.5 4345 1.91 Comparative Example 11 2:1 4.95 80 95.3 5927 1.83 Comparative Example 12 4:1 4.90 80 94.1 7850 1.95 Comparative Example 13 1:1 1 240 96.0 4421 1.25 SMA1000P / / / / 3698 1.8 SMA2000P / / / / 5150 1.9 SMA4000P / / / / 7380 1.9 As shown in Table 1, the products of Example 1 and Comparative Examples 1-3 and 13 are of the same category as SARTOMER™ SMA1000P, and in their polymer structures, styrene and maleic anhydride are alternately polymerized in a 1:1 ratio. The products of Example 2 and Comparative Examples 4-6 and 11 are of the same category as SARTOMER™ SMA2000P, and in their polymer structures, styrene and maleic anhydride are alternately polymerized in a 2:1 ratio. The products of Example 3 and Comparative Examples 7-9 and 12 are of the same category as SARTOMER™ SMA4000P, and in their polymer structures, styrene and maleic anhydride are alternately polymerized in a 4:1 ratio.

[0066] According to the data in the table, although less initiator is used in Comparative Example 1 than in Example 1, only 0.5% of the total mass of the monomer initiator can make the conversion rate of the polymerization reaction as high as 96%, but due to the limitation of the reaction vessel, it is impossible to fully mix the raw materials, and the number average molecular weight of the prepared polymer is relatively large. In addition, Comparative Example 1 adopts precipitation polymerization, which is not conducive to industrial large-scale continuous production.

[0067] Compared with Example 1, Comparative Example 2 did not add a secondary initiator. Although the mixing effect of the microchannel reactor was excellent, the liquid holding capacity was limited and the mixed product was too short in the horizontal tubular reactor, only 10 minutes, resulting in the reaction conversion rate in Comparative Example 2 being only 65%, which was too low.

[0068] Compared with Example 1, Comparative Examples 3 and 10 did not use a microchannel processor for raw material mixing and reaction, and did not add the initiator in batches. At the same time, the reaction time was too short. Therefore, even if the initiator added was 3.8 times that of Example 1, the reaction conversion rates of Comparative Examples 3 and 10 were still lower than that of Example 1, and the molecular weight distribution was wider.

[0069] As above, compared with Examples 2 and 3, Comparative Examples 11 and 12 did not use a microchannel processor for raw material mixing and reaction, and did not add the initiator in batches. At the same time, the reaction time was too short. Therefore, even if more initiator was added than in Examples 2 and 3, the reaction conversion rates of Comparative Examples 11 and 13 were still lower than those of Examples 2 and 3, and the molecular weight distribution was wider.

[0070] Although the reaction conversion rate of Comparative Example 13 is as high as 96.0% and the PDI is 1.25, the reaction temperature is as high as 240°C, which is three times that of Example 1. In actual industrial production, too high a reaction temperature will not only increase the cost, but also easily lead to the risk of overheating and explosion. Compared with Example 1, the reaction stability and safety are insufficient.

[0071] In summary, the technical solution provided by the present invention can realize the continuous production of styrene maleic anhydride copolymers with low molecular weight (number average molecular weight of 2351-6860 g / mol), narrow distribution (PDI of 1.16-1.8) and high purity (reaction conversion rate of 96%-98%) under the condition of 80-100°C, with mild reaction conditions, stable reaction process and higher safety.

[0072] The above-mentioned embodiments are preferred examples of the present invention and are not intended to limit the protection scope of the present invention.

Claims

1. A low molecular weight styrene maleic anhydride copolymer continuous flow synthesis process, characterized in that: The following steps are involved: (1) Control the temperature of styrene and maleic anhydride to T1 respectively for standby use; (2) introducing styrene, maleic anhydride and initiator into a microchannel reactor for mixing, so that a portion of the mixture of styrene, maleic anhydride and initiator is a homogeneous fluid at least at one time at the temperature T1, and reacting until the conversion rate of styrene and maleic anhydride is 50% to 70%, thereby obtaining a microchannel reaction material; (3) removing the microchannel reaction material from the microchannel reactor and introducing it into a tubular reactor to continue the reaction at a temperature of T1 until the conversion rate of styrene and maleic anhydride reaches 90% to 100%, thereby obtaining the styrene-maleic anhydride copolymer; The T1 temperature is 80°C-100°C.

2. The continuous flow synthesis process of styrene maleic anhydride copolymer according to claim 1, characterized in that: In the step (2), the initiator includes a primary initiator and a secondary initiator. The step (2) specifically includes: pumping styrene, maleic anhydride, and the primary initiator into the microchannel reactor simultaneously for preliminary mixing, until a mixture of part of styrene, maleic anhydride, and the initiator is a homogeneous fluid at least at one moment at the temperature T1, and then pumping in the secondary initiator for secondary mixing.

3. The continuous flow synthesis process of styrene maleic anhydride copolymer according to claim 2, characterized in that: In the step (2), the mass of the initiator is 1%-1.5% of the sum of the masses of styrene and maleic anhydride.

4. The continuous flow synthesis process of styrene maleic anhydride copolymer according to claim 3, characterized in that: In the step (2), the mass ratio of the secondary initiator to the primary initiator is 1:(1-3).

5. The continuous flow synthesis process of styrene maleic anhydride copolymer according to claim 4, characterized in that: In the step (2), the initiator includes at least one of azobisisoheptanonitrile, azobisisobutyronitrile, dimethyl azobisisobutyrate, azobisisobutyronitrile, and benzoyl peroxide.

6. The continuous flow synthesis process of styrene maleic anhydride copolymer according to claim 5, characterized in that: The step (2) specifically comprises: connecting a high-pressure constant-flow metering pump to the feed port of the microchannel reactor, connecting the discharge port of the microchannel reactor to the feed port of the tubular reactor, dissolving styrene, maleic anhydride, a primary initiator, and a secondary initiator in a solvent respectively, and then pumping them into the microchannel reactor using a high-pressure constant-flow metering pump.

7. The continuous flow synthesis process of styrene maleic anhydride copolymer according to claim 6, characterized in that: The solvent includes one of ethylene glycol ethyl ether acetate, butanone, ethyl butyrate, and toluene.

8. The continuous flow synthesis process of styrene maleic anhydride copolymer according to claim 1, characterized in that: In step (3), the reaction time is controlled within a range of 50 min to 90 min.

9. The continuous flow synthesis process of styrene maleic anhydride copolymer according to claim 1, characterized in that: The mass ratio of styrene to maleic anhydride is (1-4):

1.

10. A low molecular weight styrene maleic anhydride copolymer, characterized in that: The styrene maleic anhydride copolymer is prepared according to the styrene maleic anhydride copolymer continuous flow synthesis process according to any one of claims 1 to 9, and the styrene maleic anhydride copolymer has a number average molecular weight of 2000 g / mol-7000 g / mol and a molecular weight distribution PDI of 1.1-1.8.

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