A low molecular weight styrene maleic anhydride copolymer and its continuous flow synthesis process

Abstract

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

Description

TECHNICAL FIELD

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

[0002] The low molecular weight styrene maleic anhydride copolymer has good heat resistance and stability, is easy to be secondarily processed, has high surface activity and low interfacial tension, and has functions of dispersion, emulsification, thickening, crosslinking and flocculation, and is applied to the industries of coating, ink, adhesive, textile, papermaking, building material, plastic and electronics, and is a fine chemical with excellent performance and wide application.

[0003] In the prior art, there are many methods for preparing the styrene maleic anhydride copolymer, for example, patent CN101503490B discloses a synthesis method of low molecular weight styrene / maleic anhydride alternating copolymer, which adopts a four-necked bottle as a reaction container to prepare the styrene maleic anhydride alternating copolymer at 60-80℃, but the method uses the principle of precipitation polymerization to prepare the styrene maleic anhydride copolymer, and it is difficult to form continuity and mass industrial production.

[0004] Patent CN111234081A discloses a low molecular weight styrene-maleic anhydride copolymer with narrow distribution and a preparation method thereof, which adopts a tubular reactor with a static mixer as a reaction container to prepare the styrene maleic anhydride alternating copolymer at 130-300℃, and continuous production can be realized. However, the reaction temperature of the method is high, the polymerization reaction is uncontrollable, the content of maleic anhydride in the prepared copolymer fluctuates greatly, the acid value fluctuates greatly, and the content of styrene homopolymer is high.

[0005] For another example, patent CN113968927A discloses a method for synthesizing low molecular weight styrene-maleic anhydride resin by using a tubular reactor, in which the styrene, maleic anhydride and initiator are always reacted in the tubular reactor at a specific ratio by controlling the flow rates of different feeding pipes, the reaction temperature is 80℃, the residence time in the tube is 519-545s, and the reaction conversion rate is 93.6%-96.3%. The method is stable and controllable for preparing the low molecular weight styrene-maleic anhydride resin, but the molecular weight distribution is not ideal, and the PDI is 1.93-2.11. SUMMARY

[0006] The present application is carried out 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] In a first aspect, the present application provides a continuous flow synthesis process of low molecular weight styrene maleic anhydride copolymer, characterized in that it comprises the following steps:

[0008] (1) styrene and maleic anhydride are respectively controlled to T1 temperature for standby;

[0009] (2) styrene, maleic anhydride and initiator are mixed in the microchannel reactor, so that the mixture of part of styrene, maleic anhydride and initiator is a homogeneous fluid at T1 temperature at least once, and the conversion rate of styrene and maleic anhydride is 50%-70%, to obtain microchannel reaction material;

[0010] (3) the microchannel reaction material is removed from the microchannel reactor and introduced into the tubular reactor to continue the reaction at T1 temperature until the conversion rate of styrene and maleic anhydride is 90%-100%, to obtain the styrene maleic anhydride copolymer;

[0011] The T1 temperature is 80-100℃.

[0012] To solve the problem of uneven product molecular weight distribution in the preparation of styrene maleic anhydride copolymer in the prior art, the inventors try to find the reason affecting the product molecular weight distribution. Research shows that the reactivity ratio of styrene and maleic anhydride copolymerization is r1=0.04, r2=0.015, r1·r2=0.006, since the reactivity ratio of both is much smaller than 1, which means that both monomers tend to react with the active chain end of the other monomer, so the composition of the copolymer prepared by using the two monomers may deviate from the initial feed ratio, and the composition of the copolymer may change constantly with the reaction, which also leads to the product molecular weight distribution being easily uneven and the PDI being large. Maleic anhydride has a strong electron-withdrawing group, making it positive, while styrene gives electrons to become negative due to the conjugation effect of the benzene ring, so the two will form a stable positive and negative transition state of mutual attraction during copolymerization. If the two monomers are uniformly mixed in a certain proportion in theory, 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 initiator mixing, the more conducive to improving the molecular weight distribution of the product.

[0013] In the prior art, due to the small inner diameter of the micro-channel reactor and the large viscosity of the polymerization product, the micro-channel reactor is prone to be blocked, so the micro-channel reactor is generally not used for polymerization reaction. Even if the micro-channel reactor is used for reaction, due to the high reaction temperature, it is not conducive to industrial production. For example, patent CN113234308A mentions the polymerization experiment of methyl methacrylate and glycidyl methacrylate using a micro-channel reactor. In this technical solution, in order to increase the fluidity of the polymer and avoid blocking the micro-channel reactor, the reaction temperature is as high as 140℃, which not only has a high reaction temperature, but also has a high initiator addition amount of 5% of the total mass of the polymerization monomers, resulting in high production cost and being not conducive to industrial production.

[0014] Further, due to the small liquid holding capacity of the micro-channel reactor, 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 micro-channel reactors to be used in series, resulting in high instrument cost. Therefore, in the prior art, at T1 temperature (80℃-100℃), a reactor with a large inner diameter is usually used as a reaction container. For example, patent CN101503490B uses a four-necked flask as a reaction container to prepare a styrene-maleic anhydride alternating copolymer at 60-80℃; patent CN113968927A uses a tubular reactor for reaction at a reaction temperature of 80℃.

[0015] The present application uses a micro-channel reactor and a tubular reactor in series, and does not complete the whole polymerization reaction in the micro-channel reactor. Only the characteristics of the micro-channel reactor are used to realize the mixing and partial reaction of the polymerization monomers and the initiator. After the styrene and maleic anhydride and the initiator are introduced into the micro-channel reactor, the mixture of styrene, maleic anhydride and initiator will continuously collide with the inner wall of the micro-channel, and strong secondary flow, multiple vortexes and reverse collision will occur inside the mixture, so that at least one time at T1 temperature, the homogeneous fluid of the mixture of part of the styrene, maleic anhydride and initiator is formed, and the homogeneous fluid of the mixture of part of the styrene, maleic anhydride and initiator is continuously mixed with the remaining mixture, so that more mixture forms a larger volume of homogeneous fluid, thereby realizing rapid and uniform mixing of the whole mixture. The uniformly mixed mixture will quickly react to obtain a styrene-maleic anhydride copolymer. Therefore, the mixture of styrene, maleic anhydride and initiator continuously reacts in the process of flowing in the micro-channel reactor, and when the mixture leaves the micro-channel reactor, the conversion rate of styrene and maleic anhydride can reach 50%-70%, and the micro-channel reaction material is obtained.

[0016] Further, in order to prevent the micro-channel reactor from being blocked, the styrene and maleic anhydride are pretreated, and the raw materials (styrene and maleic anhydride) are respectively controlled to a T1 temperature before being fed into the micro-channel reactor, so that the viscosity of the two is reduced, the mixing efficiency of the two in the micro-channel reactor is improved, and the two reach the required reaction temperature before being fed into the micro-channel reactor, so that the two can rapidly react when being mixed in the micro-channel reactor, the reaction rate is accelerated, the reaction time of the raw materials in the micro-channel reactor is shortened, the size of the micro-channel reactor required is reduced, the reaction path of the raw materials in the micro-channel reactor is shortened, and the possibility of blockage is reduced.

[0017] Further, as the styrene-maleic anhydride copolymer is continuously produced, the viscosity of the mixture is continuously increased, in order to prevent the mixture from being precipitated due to too high viscosity and thus blocking the micro-channel reactor, the mixture is collected to obtain a micro-channel reaction material when the conversion rate of the styrene and maleic anhydride reaches 50% to 70%, and the micro-channel reaction material is removed from the micro-channel reactor and transferred to a tubular reactor for continuous production of the styrene-maleic anhydride copolymer.

[0018] The continuous flow synthesis process of the present application combines the micro-channel reactor and the tubular reactor to produce a low-molecular-weight styrene-maleic anhydride copolymer, pretreats the raw materials, uses the micro-channel reactor to perform feeding and mixing operations, and rapidly reacts in the micro-channel reactor, and then feeds the micro-channel reaction material into the tubular reactor for aging reaction.

[0019] Compared with the polymerization process of the prior art, the process of the present application uses the micro-channel reactor as a container for rapid reaction, has the advantages of fast heat transfer and high mixing efficiency, and then uses the tubular reactor as a container for aging reaction, has the advantages of high efficiency and high productivity, so that the continuous flow synthesis process of the present application can realize continuous production of a styrene-maleic anhydride copolymer with low molecular weight (number average molecular weight of 2351 to 6860 g / mol) and narrow distribution (PDI of 1.16 to 1.8) under mild reaction conditions and with low initiator addition amount, and the reaction process is stable, has higher safety, and the monomer conversion rate is as high as 98%.

[0020] In some embodiments, the initiator in step (2) includes a primary initiator and a secondary initiator, and step (2) specifically includes: pumping the styrene, the maleic anhydride and the primary initiator into the micro-channel reactor for preliminary mixing, and pumping the secondary initiator for secondary mixing when the mixture of the partial styrene, the maleic anhydride and the initiator is a homogeneous fluid at least one time at the T1 temperature.

[0021] Compared with the prior art, the whole polymerization process is divided into three stages for reaction, in the first stage, styrene, maleic anhydride and primary initiator are preliminarily mixed and reacted in a micro-channel reactor; in the second stage, styrene, maleic anhydride, primary initiator and pumped secondary initiator are secondarily mixed and reacted in the micro-channel reactor; in the third stage, the uniformly mixed styrene, maleic anhydride, primary initiator and secondary initiator are subjected to curing reaction in a tubular reactor. By adding initiators in steps, the initiators and raw materials can be more fully mixed, so as to control the reaction rate and reaction degree in each stage respectively, thereby improving the stability and safety of the reaction, so that the initiators can be maximizedly utilized and the monomer conversion rate is improved without increasing or even reducing the amount of initiators.

[0022] Meanwhile, in the examples, the initiators are divided into primary initiators and secondary initiators, which are mixed with raw materials in batches, the raw materials are preliminarily mixed with the primary initiators to react, after the reaction is stable, the secondary initiators are pumped into the later stage of the micro-channel reactor 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 initiators at one time, the polymerization reaction speed can be prevented from being too fast, the reaction system temperature can be prevented from rising sharply, the reaction can be prevented from being too violent, and even the safety hidden danger such as explosion can be prevented.

[0023] Through experimental detection, when the styrene, maleic anhydride and primary initiator are pumped into the micro-channel reactor to preliminarily mix for 0.1-10 min, the mixture of part of the styrene, maleic anhydride and initiator in the micro-channel reactor can be ensured to be a homogeneous fluid at least one time at T1 temperature, at this time, the secondary initiator is pumped in for secondary mixing to further initiate the reaction.

[0024] In some examples, in the step (2), the mass of the initiator is 1%-1.5% of the sum of the mass of styrene and maleic anhydride. Through ingenious experimental design, the utilization rate of the initiator is improved, so that in the examples, only 1%-1.5% of the initiator of the sum of the mass of styrene and maleic anhydride can achieve a reaction conversion rate of 98%, compared with the prior art, the initiator content is lower, and the effect is remarkable.

[0025] In some examples, in the step (2), the mass ratio of the secondary initiator to the primary initiator is 1: (1-3). In the examples, the mass of the primary initiator needs to be greater than that 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 micro-channel reactor, when the mixture reaches the second half of the micro-channel reactor, the degree of polymerization reaction is gradually reduced, the secondary initiator is added, and after further mixing and initiating reaction in the second stage, the mixed product is pumped into the tubular reactor to enter the third stage for curing reaction.

[0026] In some embodiments, the initiator in step (2) comprises at least one of azobisisoheptane nitrile, azobisisobutyronitrile, dimethyl azobisisobutyrate, azobisisobutyronitrile, and benzoyl peroxide. In embodiments, the above initiator requires mild reaction conditions, and the polymerization reaction initiated by the initiator is relatively fast, which can further shorten the reaction time, improve the production efficiency, and reduce the possibility of clogging.

[0027] In some embodiments, step (2) specifically comprises connecting a high-pressure constant-flow metering pump to the feed inlet of the micro-channel reactor, connecting the outlet of the micro-channel reactor to the feed inlet of the tubular reactor, and pumping styrene, maleic anhydride, primary initiator, and secondary initiator into the micro-channel reactor after dissolving them in a solvent using a high-pressure constant-flow metering pump.

[0028] In some embodiments, the solvent comprises one of ethylene glycol ethyl ether acetate, butanone, ethyl butyrate, toluene, and the like.

[0029] In some embodiments, in step (3), the reaction time is controlled to be 50-90 minutes.

[0030] In embodiments, the mixed product mixed sufficiently in the micro-channel reactor needs to be subjected to a curing reaction in the 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.

[0031] In some embodiments, the mass ratio of styrene to maleic anhydride is (1-4):1.

[0032] In a second aspect, the present application provides a low molecular weight styrene maleic anhydride copolymer, characterized in that the styrene maleic anhydride copolymer is prepared by the continuous flow synthesis process according to any one of the styrene maleic anhydride copolymers of the first aspect, and the number average molecular weight of the styrene maleic anhydride copolymer is 2000-7000 g / mol, and the molecular weight distribution PDI is 1.1-1.8.

[0033] By implementing the above technical solutions, the present application has the following beneficial effects:

[0034] The continuous flow synthesis process of the present application combines a micro-channel reactor and a tubular reactor for producing a low molecular weight styrene maleic anhydride copolymer, pretreats the raw materials, utilizes the characteristics of the micro-channel reactor that can efficiently mix the raw materials, performs feeding and mixing operations using the micro-channel reactor, and rapidly performs a reaction in the micro-channel reactor, and then passes the micro-channel reactor material into the tubular reactor for a curing reaction.

[0035] Compared with the polymerization process of the prior art, the process of the present application uses a microchannel reactor as a container for rapidly performing reactions, has the advantages of fast heat transfer and high mixing efficiency, and further uses a tubular reactor as a container for maturation reactions, has the advantages of high efficiency and high productivity, so that the continuous flow synthesis process of the present application can realize continuous production of styrene maleic anhydride copolymer with low molecular weight (number average molecular weight is 2351-6860 g / mol) and narrow distribution (PDI is 1.16-1.8) under mild reaction conditions (reaction temperature is 80-100℃), low initiator addition amount (the required initiator mass is only 1%-1.5% of the total mass of the polymer monomer), low cost of industrial production, stable reaction process, higher safety, and high monomer conversion rate of up to 98%.

[0036] Compared with the prior art, the present application controls the reaction rate and reaction degree in each stage by stepwise addition of the initiator, so as to improve the stability and safety of the reaction, thereby maximizing the use of the initiator without increasing or even reducing the amount of the initiator, and improving the monomer conversion rate. BRIEF DESCRIPTION OF DRAWINGS

[0037] Figure 1 is the infrared spectrum of the styrene maleic anhydride copolymer in Example 1 of the present application;

[0038] Figure 2 is the polarizing microscope graph of the styrene maleic anhydride copolymer in Example 2 of the present application;

[0039] Figure 3 is the gel chromatography molecular weight test result of SARTOMER™ SMA1000P;

[0040] Figure 4 is the gel chromatography molecular weight test result of the styrene maleic anhydride copolymer in Example 1. DETAILED DESCRIPTION

[0041] In order to make the technical means, creative features, purposes and effects realized by the present application easy to understand, the present application is specifically described below in combination with examples and drawings.

[0042] Example 1

[0043] Reaction device: Tesla channel micro-channel reactor, single piece size 225x170mm, material silicon carbide, single piece liquid holding capacity / reaction volume is 50ml, maximum flux 20kg / hour, using 5 pieces of micro-channel reactor in series integration; 4 high-pressure constant flow metering pumps, double plunger parallel mode, flow range 20ml~500ml / min, increment 0.1ml / min, maximum pressure 10MPa, high-pressure constant flow metering pump, double plunger parallel mode, flow range 30ml~1000ml / min; horizontal pipe reactor, material 316L stainless steel pipe, pipe diameter is 2.1cm; temperature control system, explosion-proof mold temperature machine refrigeration heating all-in-one machine 2 sets, respectively control micro-channel reactor and horizontal pipe reactor temperature, -25℃~200℃, temperature control accuracy ±0.5℃.

[0044] Reaction device connection relationship: the outlet of the 3 high-pressure constant flow metering pumps connected with A tank, B tank and C tank is connected with the inlet of the first piece of micro-channel reactor by using multi-way valve, the outlet of the first piece of micro-channel reactor is connected with the inlet of the second piece of micro-channel reactor, the outlet of the second piece is connected with the inlet of the third piece of micro-channel reactor, and the third piece and the fourth piece of micro-channel reactor are connected in turn, the inlet of the fifth piece of micro-channel reactor is connected with the outlet of the fourth piece of micro-channel reactor and the outlet of the high-pressure constant flow metering pump connected with D tank by using three-way valve, and the outlet of the fifth piece of micro-channel reactor is connected with the inlet of the horizontal pipe reactor by quick connection.

[0045] Material preparation: 2083 grams of styrene monomer and 4000 grams of ethylene glycol ether acetate are mixed in A tank and heated to 80℃ as component one; 1960 grams of maleic anhydride are dissolved in 4750 grams of ethylene glycol ether acetate in B tank and heated to 80℃ as component two; 37.7 grams of azobis diisopropyl cyanide are dissolved in 2000 grams of ethylene glycol ether acetate solvent in C tank as component three; 15 grams of benzoyl peroxide are dissolved in 1000 grams of ethylene glycol ether acetate as component four in D tank.

[0046] The A tank component one is pumped into the first piece of micro channel reactor at a flow rate of 304.15 ml / min, the B tank component two is pumped into the first piece of micro channel reactor at a flow rate of 335.5 ml / min, the C tank component three is pumped into the first piece of micro channel reactor at a flow rate of 101.88 ml / min, the reaction temperature is controlled at 80 ℃, the component one, the component two and the component three are contacted at the inlet of the first piece of micro channel reactor and are mixed in the first piece of micro channel reactor at the same time, and then flow into the other micro channel reactors in series, the D tank component four is pumped into the fifth piece of micro channel reactor at a flow rate of 50.75 ml / min after 2 minutes, the component four is contacted with the component one, the component two and the component three at the inlet of the fifth piece of micro channel reactor, and is mixed in the fifth piece of micro channel reactor, and after the micro channel reaction, the sample is taken at the outlet and the conversion rate of styrene and maleic anhydride is monitored by gas chromatography to reach 50%~70%, and the micro channel reaction material is obtained. The micro channel reaction material is pumped into the horizontal tubular reactor, the temperature is kept at 80 ℃, and the reaction is continued, and the residence time of the reaction in the horizontal tubular reactor is 60 minutes. The reaction product is dehydrated by a vacuum rotary blade film process to remove the solvent, and a white powder is obtained. The total yield of the product is about 98.0%, the number average molecular weight is 2351 g / mol, and the molecular weight distribution PDI is 1.16.

[0047] Example 2

[0048] Reaction device: core type channel micro channel reactor, single piece size 225x170mm, material silicon carbide, single piece liquid holding capacity / reaction volume is 50ml, maximum flux 20kg / hour, using 5 pieces of micro channel reactor in series integration; 4 high pressure constant flow metering pumps, double plunger parallel flow mode, flow range 20ml~500ml / min, increment 0.1ml / min, maximum pressure 10MPa, high pressure constant flow metering pump, double plunger parallel flow mode, flow range 30ml~1000ml / min; horizontal tubular reactor, material 316L stainless steel pipe, pipe diameter is 2.1cm, the inlet is connected to the outlet of the micro channel reactor; temperature control system, 2 sets of explosion-proof mold temperature machine refrigeration and heating integrated machine, respectively control the temperature of the micro channel reactor and the horizontal tubular reactor, -25℃~200℃, temperature control accuracy ±0.5℃.

[0049] Reaction device connection relationship: the outlets of the 3 high pressure constant flow metering pumps connected with the A tank, the B tank and the C tank are connected with the inlet of the first piece of micro channel reactor by using multi-way valve, the outlet of the first piece of micro channel reactor is connected with the inlet of the second piece of micro channel reactor, the outlet of the second piece is connected with the inlet of the third piece of micro channel reactor, the third piece and the fourth piece of micro channel reactor are connected in series, the inlet of the fifth piece of micro channel reactor is connected with the outlet of the fourth piece of micro channel reactor and the outlet of the high pressure constant flow metering pump connected with the D tank by using three-way valve, and the outlet of the fifth piece of micro channel reactor is connected with the inlet of the horizontal tubular reactor.

[0050] Material preparation: 2770.4 grams of styrene monomer and 4000 grams of butanone were mixed in an A tank and heated to 100°C as component one; 1304.2 grams of maleic anhydride were dissolved in 4750 grams of butanone in a B tank and heated to 100°C as component two; 37.7 grams of azobisisobutyronitrile were dissolved in 2000 grams of butanone solvent in a C tank as component three; 15 grams of benzoyl peroxide were dissolved in 1000 grams of butanone in a D tank as component four.

[0051] The A tank component one was pumped into the first piece of micro-channel reactor at a flow rate of 338.52 ml / min, the B tank component two was pumped into the first piece of micro-channel reactor at a flow rate of 302.71 ml / min, and the C tank component three was pumped into the first piece of micro-channel reactor at a flow rate of 101.88 ml / min. The reaction temperature was controlled at 100°C. The component one, the component two and the component three were contacted at the inlet of the first piece of micro-channel reactor and mixed in the first piece of micro-channel reactor at the same time, and then flowed into the other micro-channel reactors in series. After 2 minutes, the D tank component four was pumped into the fifth piece of micro-channel reactor at a flow rate of 50.75 ml / min. The component four was contacted with the component one, the component two and the component three at the inlet of the fifth piece of micro-channel reactor, mixed in the fifth piece of micro-channel reactor, and reacted in the micro-channel. After the micro-channel reaction, the sample was taken at the outlet and the conversion rate of styrene and maleic anhydride was monitored by gas chromatography. When the conversion rate reached 50%~70%, the micro-channel reaction material was obtained. The micro-channel reaction material was pumped into the horizontal tube reactor, and the temperature was maintained at 100°C for continuous reaction. The residence time in the horizontal tube reactor was 60 minutes. The reaction product was treated by vacuum rotary blade film process to remove the solvent, and a white powder was obtained. 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.

[0052] Example 3

[0053] Reaction device: octopus channel micro-channel reactor, single piece size 225x170mm, material silicon carbide, single piece liquid holding capacity / reaction volume is 50ml, maximum flux 20kg / hour, using 5 pieces of micro-channel reactor in series integration; 4 high-pressure constant-flow metering pumps, double-plunger parallel-flow mode, flow range 20ml~500ml / min, increment 0.1ml / min, maximum pressure 10MPa, high-pressure constant-flow metering pump, double-plunger parallel-flow mode, flow range 30ml~1000ml / min; horizontal tube reactor, material 316L stainless steel tube, pipe diameter is 2.1cm, the inlet is connected to the outlet of the micro-channel reactor; temperature control system, 2 sets of explosion-proof mold temperature machine refrigeration and heating integrated machine, respectively control the temperature of the micro-channel reactor and the horizontal tube reactor, -25℃~200℃, temperature control accuracy ±0.5℃.

[0054] The outlet of the three high-pressure constant-flow metering pumps connected with the A tank, the B tank, and the C tank is connected with the inlet of the first piece of micro-channel reactor by using a multi-way valve, the outlet of the first piece of micro-channel reactor is connected with the inlet of the second piece of micro-channel reactor, the outlet of the second piece is connected with the inlet of the third piece of micro-channel reactor, the third piece and the fourth piece of micro-channel reactor are connected in series, the inlet of the fifth piece of micro-channel reactor is connected with the outlet of the fourth piece of micro-channel reactor and the outlet of the high-pressure constant-flow metering pump connected with the D tank by using a three-way valve, and the outlet of the fifth piece of micro-channel reactor is connected with the inlet of the horizontal tube reactor by quick docking.

[0055] Material preparation: 4166 grams of styrene monomer and 6000 grams of ethyl butyrate are mixed in the A tank and heated to 90°C as component one; 980 grams of maleic anhydride are dissolved in 2750 grams of ethyl butyrate in the B tank and heated to 90°C as component two; 37.7 grams of dimethyl azobisisobutyrate are dissolved in 2000 grams of ethyl butyrate solvent in the C tank as component three; and 15 grams of azobisisobutyronitrile are dissolved in 1000 grams of ethyl butyrate in the D tank as component four.

[0056] The component one in the A tank is pumped into the first piece of micro-channel reactor at a flow rate of 508.3 ml / min, the component two in the B tank is pumped into the first piece of micro-channel reactor at a flow rate of 186.5 ml / min, and the component three in the C tank is pumped into the first piece of micro-channel reactor at a flow rate of 101.88 ml / min, the reaction temperature is controlled at 90°C, the component one, the component two, and the component three are contacted at the inlet of the first piece of micro-channel reactor and mixed in the first piece of micro-channel reactor at the same time, and then flow into the other micro-channel reactors in series, after 2 minutes, the component four in the D tank is pumped into the fifth piece of micro-channel reactor at a flow rate of 50.75 ml / min, the component four is contacted with the component one, the component two, and the component three at the inlet of the fifth piece of micro-channel reactor, and mixed in the fifth piece of micro-channel reactor, after the micro-channel reaction, the sample is taken at the outlet and the conversion rate of styrene and maleic anhydride is monitored by using gas chromatography, the conversion rate reaches 50%~70%, and the micro-channel reaction material is obtained. The micro-channel reaction material is pumped into the horizontal tube reactor, the temperature is maintained at 90°C, and the reaction continues for 60 minutes in the horizontal tube reactor. The reaction product is subjected to vacuum rotary blade film process to remove the solvent, and a white powder is obtained. The total yield of the product is about 96.0%, the number average molecular weight is 6860 g / mol, and the molecular weight distribution PDI is 1.8.

[0057] Comparative Example 1

[0058] This comparative example refers to the technical solution of patent CN 101503490 B for experiment, and the specific experimental steps are as follows:

[0059] Into a 250 ml four-necked flask, equipped with an electric stirrer, thermometer and reflux condenser, 150 ml of toluene, 10.4 g (0.10 mol) of styrene, 9.8 g (0.10 mol) of maleic anhydride and 0.1 g of dibenzoyl peroxide were introduced. The temperature was raised to about 50°C and, after 15 min of stirring, the maleic anhydride was completely dissolved. Then, the temperature was raised to about 80°C and the reaction was carried out for 1 h. During the reaction, the product gradually precipitated and the reaction mixture became increasingly difficult to stir. The heating was stopped and the reaction mixture was allowed to cool to room temperature. The product was filtered off and dried under vacuum at 60°C. The overall yield of the product was about 96.0% and the number average molecular weight was 10500 g / mol with a molecular weight distribution PDI of 1.8.

[0060] Comparative Example 2

[0061] This comparative example was tested according to Example 1, except that no secondary initiator was added in this comparative example. The specific experimental steps are as follows:

[0062] Reaction device: Tesla channel micro-channel reactor, single piece size 225x170mm, material silicon carbide, single piece liquid holding capacity / reaction volume is 50ml, maximum flux 20kg / hour, using 5 pieces of micro-channel reactor in series integration; 3 high-pressure constant-flow metering pumps, double-plunger parallel-flow mode, flow range 20ml~500ml / min, increment 0.1ml / min, maximum pressure 10MPa, high-pressure constant-flow metering pump, double-plunger parallel-flow mode, flow range 30ml~1000ml / min; horizontal pipe reactor, material 316L stainless steel pipe, pipe diameter is 2.1cm; temperature control system, explosion-proof mold temperature machine refrigeration heating all-in-one machine 2 sets, respectively control micro-channel reactor and horizontal pipe reactor temperature, -25℃~200℃, temperature control accuracy ±0.5℃.

[0063] Reaction device connection relationship: the outlet of the 3 high-pressure constant-flow metering pumps connected with A tank, B tank, C tank respectively is connected with the inlet of the first piece of micro-channel reactor by multi-way valve, the outlet of the first piece of micro-channel reactor is connected with the inlet of the second piece of micro-channel reactor, the outlet of the second piece is connected with the inlet of the third piece of micro-channel reactor, and the third piece, the fourth piece of micro-channel reactor, the fifth piece of micro-channel reactor are connected in turn, and the outlet of the fifth piece of micro-channel reactor is connected with the inlet of the horizontal pipe reactor.

[0064] Material preparation: 2083 grams of styrene monomer and 4000 grams of ethylene glycol ether acetate are mixed in A tank and heated to 80°C as component one; 1960 grams of maleic anhydride are dissolved in 4750 grams of ethylene glycol ether acetate in B tank and heated to 80°C as component two; 37.7 grams of azobisisoheptyl nitrile are dissolved in 2000 grams of ethylene glycol ether acetate solvent in C tank as component three.

[0065] The A tank component one was pumped into the first piece core-shaped micro-channel reactor at a flow rate of 304.15 ml / min, the B tank component two was pumped into the first piece core-shaped micro-channel reactor at a flow rate of 335.5 ml / min, and the C tank component three was pumped into the first piece core-shaped micro-channel reactor at a flow rate of 101.88 ml / min. The reaction temperature was controlled at 80 ℃. The component one, the component two and the component three were contacted at the inlet of the first piece micro-channel reactor, mixed in the first piece micro-channel reactor at the same time, flowed into the other micro-channel reactors in series, and were pumped into the horizontal tubular reactor after the micro-channel reaction. The residence time of the reaction in the horizontal tubular reactor was 600 s. The reaction product was collected and the solvent was removed by a vacuum rotary blade film process to obtain a white powder. The total yield of the product was about 65.0%, the number average molecular weight was 1100 g / mol, and the molecular weight distribution PDI was 1.3.

[0066] Comparative Example 3

[0067] This comparative example refers to the technical solution of patent CN 113968927A for experiment. The specific experimental steps are as follows:

[0068] Test device: horizontal tubular reactor, material 316L stainless steel pipe, pipe diameter 2.1 cm; high-pressure constant-flow metering pump, double-plunger parallel-flow mode, flow range 30 ml-1000 ml / min; temperature control system, explosion-proof modular temperature control refrigeration and heating all-in-one machine 2 sets, -25 ℃-200 ℃, temperature control accuracy ±0.5 ℃.

[0069] Maleic anhydride 1164 g, azobisisobutyronitrile 94.5 g and butanone 1800 g were prepared into component A; styrene 1234.5 g, azobisisobutyronitrile 25.5 g and butanone 1800 g were prepared into component B; the component A and the component B materials were respectively sent into the tubular reactor at a speed of 330 mL / min by using a high-pressure constant-flow metering pump, the polymerization temperature was controlled at 80 ℃, the residence time of the reaction was 545 s, the reaction product was removed by a vacuum rotary blade film process to obtain a white powder. The total yield of the product was about 90.0%, the number average molecular weight was 4300 g / mol, and the molecular weight distribution PDI was 1.9.

[0070] Comparative Example 4

[0071] This comparative example refers to Comparative Example 1 for experiment. Different from Comparative Example 1, in this comparative example, the amount of raw materials was 13.6 g of styrene and 6.6 g of maleic anhydride, and the reaction temperature was 100 ℃. The total yield of the product was about 90.0%, the number average molecular weight was 6630 g / mol, and the molecular weight distribution PDI was 2.1.

[0072] Comparative Example 5

[0073] The present comparative example was tested according to Comparative Example 2, except that in the present comparative example, the amount of raw materials was 2695 g of styrene and 1350 g of maleic anhydride, and the reaction temperature was 100°C. The total product yield was about 60.0%, the number average molecular weight was 4880 g / mol, and the molecular weight distribution PDI was 1.5.

[0074] Comparative Example 6

[0075] The present comparative example was tested according to Comparative Example 3, except that in the present comparative example, the amount of raw materials was 1600 g of styrene and 800 g of maleic anhydride, and the reaction temperature was 100°C. The total product yield was about 60.0%, the number average molecular weight was 4880 g / mol, and the molecular weight distribution PDI was 1.5.

[0076] Comparative Example 7

[0077] The present comparative example was tested according to Comparative Example 1, except that in the present comparative example, the amount of raw materials was 16.0 g of styrene and 4.0 g of maleic anhydride, and the reaction temperature was 90°C. The total product yield was about 86.0%, the number average molecular weight was 8960 g / mol, and the molecular weight distribution PDI was 2.3.

[0078] Comparative Example 8

[0079] The present comparative example was tested according to Comparative Example 2, except that in the present comparative example, the amount of raw materials was 3235 g of styrene and 810 g of maleic anhydride, and the reaction temperature was 90°C. The total product yield was about 62.0%, the number average molecular weight was 7150 g / mol, and the molecular weight distribution PDI was 1.9.

[0080] Comparative Example 9

[0081] The present comparative example was tested according to Comparative Example 3, except that in the present comparative example, the amount of raw materials was 1920 g of styrene and 480 g of maleic anhydride, and the reaction temperature was 90°C. The total product yield was about 65.0%, the number average molecular weight was 8210 g / mol, and the molecular weight distribution PDI was 2.1.

[0082] Comparative Example 10

[0083] The present comparative example was selected from Example 1 of patent CN 113968927A, and the specific content is as follows:

[0084] In the first ingredient tank, maleic anhydride 77.6 g, azobisisobutyronitrile 6.3 g and butanone 120 g were added to prepare reaction liquid A; in the second ingredient tank, styrene 82.3 g, azobisisobutyronitrile 1.7 g and butanone 120 g were added to prepare reaction liquid B; the polymerization monomer mixed solution was kept at 10°C. Nitrogen was introduced into the first ingredient tank and the second ingredient tank for 40 min respectively to remove the oxygen mixed in the monomer mixed solution, and the mass of oxygen in the system was controlled to be less than 2 ppm. The materials were sent into the tubular reactor at a speed of 22 mL / min through the first raw material pump and the second raw material pump respectively, the system pressure was monitored through the first pressure gauge and the second pressure gauge during the whole process, and the pipeline pressure was adjusted to 2 MPa through the back pressure valve. The polymerization temperature in the tubular reactor was controlled to be 80°C through the oil bath pot 8, and the reaction residence time was 545 s. The reaction product flowed out of the reactor in a continuous flow state after being cooled by the ice water bath of the cooling coil, and the reaction liquid was collected and dried in the product collection tank to obtain colorless transparent polymer. The total yield of the product was about 96.5%, the number average molecular weight was 4345 g / mol, and the molecular weight distribution PDI was 1.91.

[0085] Comparative Example 11

[0086] This comparative example is selected from Example 2 of patent CN 113968927A, and the specific content is as follows:

[0087] In the first ingredient tank, maleic anhydride 77.6 g, azobisisobutyronitrile 6.3 g and butanone 120 g were added to prepare reaction liquid A; in the second ingredient tank, styrene 82.3 g, azobisisobutyronitrile 1.7 g and butanone 120 g were added to prepare reaction liquid B; the polymerization monomer mixed solution was kept at 10°C. Nitrogen was introduced into the first ingredient tank and the second ingredient tank for 40 min respectively to remove the oxygen mixed in the monomer mixed solution, and the mass of oxygen in the system was controlled to be less than 2 ppm. The materials were sent into the tubular reactor at a speed of 22 mL / min through the first raw material pump and the second raw material pump respectively, the system pressure was monitored through the first pressure gauge and the second pressure gauge during the whole process, and the pipeline pressure was adjusted to 2 MPa through the back pressure valve. The polymerization temperature in the tubular reactor was controlled to be 80°C through the oil bath pot 8, and the reaction residence time was 545 s. The reaction product flowed out of the reactor in a continuous flow state after being cooled by the ice water bath of the cooling coil, and the reaction liquid was collected and dried in the product collection tank to obtain colorless transparent polymer. The total yield of the product was about 96.5%, the number average molecular weight was 4345 g / mol, and the molecular weight distribution PDI was 1.91.

[0088] Comparative Example 12

[0089] This comparative example is selected from Example 4 of patent CN 113968927A, and the specific content is as follows:

[0090] In the first ingredient tank, maleic anhydride 31.1 g, azobisisobutyronitrile 1.6 g and 48 g butanone were added to prepare reaction liquid A; in the second ingredient tank, styrene 132 g, azobisisobutyronitrile 6.4 g and 192 g butanone were added to prepare reaction liquid B; the polymerization monomer mixed solution was kept at 10°C. Nitrogen was introduced into the first ingredient tank and the second ingredient tank for 40 min, and the oxygen mass in them was controlled to be below 2 ppm. Reaction liquid A and reaction liquid B were sent into the tubular reactor at a speed of 8.7 mL / min and 35.6 mL / min respectively through the first raw material pump and the second raw material pump 4, the system pressure was monitored through the first pressure gauge and the second pressure gauge, and the pipeline pressure was adjusted to 2.5 MPa through the back pressure valve. The polymerization temperature in the tubular reactor was controlled to be 80°C through the oil bath pot, and the reaction residence time was 521 s.

[0091] The reaction product flowed out of the reactor in a continuous flow state after being cooled by the cooling coil ice water bath, and the reaction liquid was collected, dried and then a colorless transparent polymer was obtained. The total product yield was about 94.1%, the number average molecular weight was 7850 g / mol, and the molecular weight distribution PDI was 1.95.

[0092] Comparative Example 13

[0093] This comparative example is selected from Example 11 of patent CN 111234081A, and the specific content is as follows:

[0094] Material ratio: solvent cyclohexanone 30 kg, accounting for 30% of the total mass of all materials; monomer maleic anhydride and styrene molar ratio 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.

[0095] Preparation of copolymer: styrene, maleic anhydride, initiator and reaction solvent were added to the monomer mixed reaction kettle, after nitrogen was used to remove air, stirring and mixing until maleic anhydride was dissolved, then the obtained mixture was uniformly sent to the tubular reactor at 240°C by using the feeding pump, the residence time of the mixture was 10 min, the obtained reaction material was transported to the devolatilizer for devolatilization to obtain low molecular weight narrow distribution styrene-maleic anhydride copolymer and devolatilization material; the low molecular weight narrow distribution styrene-maleic anhydride copolymer obtained by devolatilization was discharged through a melt pump, then granulated and packaged to obtain the finished product; the devolatilization material obtained by devolatilization was condensed in the condensing system, the obtained recovered material was stored in the recovered monomer storage tank, and then refined, and the obtained material was reused for polymerization reaction. The total product yield was about 96.0%, the number average molecular weight was 4421 g / mol, and the molecular weight distribution PDI was 1.25.

[0096] Data comparison and analysis

[0097] The detection and data analysis were performed according to the above-mentioned examples 1-3, comparative examples 1-13, and the market products SARTOMER™ SMA1000P, SARTOMER™ SMA2000P, SARTOMER™ SMA4000P, and the results are shown in Table 1:

[0098] Table 1. Results of sample detection of examples, comparative examples

[0099] Sample Monomer ratio Initiator (%) Reaction temperature (°C) Reaction conversion (%) 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 SMA 1000 P / / / / 3698 1.8 SMA 2000 P / / / / 5150 1.9 SMA 4000 P / / / / 7380 1.9

[0100] As shown in Table 1, the products of example 1 and comparative examples 1-3, 13 are of the same category as SARTOMER™ SMA1000P, which is 1:1 alternating polymerization of styrene and maleic anhydride in the polymer structure, the products of example 2 and comparative examples 4-6, 11 are of the same category as SARTOMER™ SMA2000P, which is 2:1 alternating polymerization of styrene and maleic anhydride in the polymer structure, and the products of example 3 and comparative examples 7-9, 12 are of the same category as SARTOMER™ SMA4000P, which is 4:1 alternating polymerization of styrene and maleic anhydride in the polymer structure.

[0101] 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, the conversion rate of the polymerization reaction is as high as 96%, but due to the limitation of the reaction container, the raw materials cannot be fully mixed, the number average molecular weight of the prepared polymer is large, and comparative example 1 uses a precipitation polymerization method, which is not conducive to the continuous production of large quantities in industrialization.

[0102] Comparative example 2 does not add a secondary initiator compared to example 1, although the mixing effect of the microchannel reactor is excellent, but due to the limited liquid holdup, and the mixing product in the horizontal tubular reactor is too short, only 10 min, resulting in a reaction conversion rate of only 65% in comparative example 2, which is too low.

[0103] Comparative examples 3 and 10 do not use a microchannel processor for raw material mixing and reaction compared to example 1, and do not add the initiator in batches, and the reaction time is too short, so even if the initiator added is 3.8 times that of example 1, the reaction conversion rate of comparative examples 3 and 10 is still lower than that of example 1, and the molecular weight distribution is wider.

[0104] As above, comparative examples 11 and 12 do not use a microchannel processor for raw material mixing and reaction compared to examples 2 and 3, and do not add the initiator in batches, and the reaction time is too short, so even if the initiator added is more than examples 2 and 3, the reaction conversion rate of comparative examples 11 and 13 is still lower than that of examples 2 and 3, and the molecular weight distribution is wider.

[0105] 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℃, which is 3 times of that of Example 1. In actual industrial production, a too high reaction temperature not only increases the cost, but also easily causes overheating and explosion. Compared with Example 1, the reaction stability and safety of Comparative Example 13 are insufficient.

[0106] In summary, the technical scheme provided by the present application can realize continuous production of styrene maleic anhydride copolymer 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℃. The reaction condition is mild, the reaction process is stable, and the safety is higher.

[0107] The above embodiments are preferred cases of the present application and do not limit the protection scope of the present application.

Claims

1. A continuous flow process for the synthesis of low molecular weight styrene maleic anhydride copolymer characterized in that, The method comprises the following steps: (1) controlling the temperature of styrene and maleic anhydride to T1 respectively for standby; (2) mixing styrene, maleic anhydride and an initiator in a micro-channel reactor to make the mixture of part of styrene, maleic anhydride and the initiator be a homogeneous fluid at least once at T1, and to react until the conversion rate of styrene and maleic anhydride is 50-70%, to obtain a micro-channel reaction material; (3) moving the micro-channel reaction material out of the micro-channel reactor and into a tubular reactor to maintain T1 and continue to react until the conversion rate of styrene and maleic anhydride is 90-100%, to obtain the styrene-maleic anhydride copolymer; The T1 temperature is 80-100℃; in the step (2), the initiator comprises a primary initiator and a secondary initiator, and the mass ratio of the secondary initiator to the primary initiator is 1: (1-3); the step (2) specifically comprises: pumping styrene, maleic anhydride and the primary initiator into the micro-channel reactor for preliminary mixing, and pumping the secondary initiator for secondary mixing when the mixture of part of styrene, maleic anhydride and the initiator is a homogeneous fluid at least once at T1. In the step (2), the mass of the initiator is 1-1.5% of the sum of the mass of styrene and maleic anhydride.

2. The continuous flow synthesis process of a styrene maleic anhydride copolymer according to claim 1, characterized in that, In the step (2), the initiator at least comprises one of azobisdiisopropyl cyanide, azobisdiisobutyl cyanide, azobisdiisobutyl acid dimethyl ester and benzoyl peroxide.

3. The continuous flow synthesis process of a styrene maleic anhydride copolymer according to claim 2, characterized in that, The step (2) specifically comprises: connecting a high-pressure constant-flow metering pump with the feeding port of the micro-channel reactor, connecting the discharging port of the micro-channel reactor with the feeding port of the tubular reactor, dissolving styrene, maleic anhydride, the primary initiator and the secondary initiator in a solvent, and pumping them into the micro-channel reactor by using the high-pressure constant-flow metering pump.

4. The continuous flow synthesis process of a styrene maleic anhydride copolymer according to claim 3, characterized in that, The solvent comprises one of ethylene glycol ether acetate, butanone, ethyl butyrate, toluene and the like.

5. The continuous flow synthesis process of a styrene maleic anhydride copolymer according to claim 4, characterized in that, In the step (3), the reaction time is controlled to be 50-90 min.

6. The continuous flow process for the synthesis of styrene maleic anhydride copolymer of claim 1, wherein, The mass ratio of styrene to maleic anhydride is (1-4):

1.

7. The continuous flow process for the synthesis of styrene maleic anhydride copolymer according to claim 1, characterized in that, ​

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