Preparation method of syndiotactic polystyrene

Abstract

The invention relates to a preparation method of syndiotactic polystyrene. The preparation method comprises the following steps: adding styrene, a main catalyst and a cocatalyst into a reactor, and carrying out bulk polymerization to obtain syndiotactic polystyrene. The syndiotactic polystyrene is synthesized in a bulk polymerization manner, and low swelling and caking and high single-kettle yield can be taken into account through cooperation of the specific main catalyst and the specific reactor, so that the production efficiency is greatly improved, and the production cost is reduced. In addition, the preparation method provided by the invention can also enable the catalyst to show high catalytic activity.

Description

Technical Field

[0001] The present invention relates to the technical field of chemical industry, and more specifically, to a method for preparing syndiotactic polystyrene. Background Art

[0002] Syndiotactic polystyrene (sPS) is a type of polystyrene that has the good chemical inertness, excellent electrical insulation and moisture resistance of general-purpose polystyrene. Unlike general-purpose polystyrene, the molecular chain configuration of syndiotactic polystyrene is syndiotactic, and the side groups (benzene rings) in the structural unit are arranged alternately on both sides of the macromolecular chain. Since syndiotactic polystyrene has high stereoregularity and strong crystallization ability, syndiotactic polystyrene is a crystallizable polymer with a crystalline melting point of about 270°C. The highly crystalline aggregate structure gives syndiotactic polystyrene good heat resistance and corrosion resistance, making its performance comparable to thermoplastic engineering plastics such as nylon, polyester, and polyphenylene sulfide, making it a cost-effective engineering plastic.

[0003] At present, the main production process of syndiotactic polystyrene is solution polymerization, such as the Chinese patent with publication number CN1252100A. The solution polymerization method requires the addition of a solvent of equivalent mass to the styrene monomer for dilution. This method can well solve the swelling and agglomeration problem in the production process of syndiotactic polystyrene. However, the single-pot yield of syndiotactic polystyrene produced by the solution polymerization method is low (single-pot yield = monomer concentration × monomer conversion rate. At the same monomer conversion rate, the single-pot yield of the solution polymerization method is significantly lower than that of bulk polymerization), which is not conducive to the control of production costs and the improvement of production efficiency of enterprises. In addition, solution polymerization also involves the distillation recovery of solvents, and the process is relatively complicated.

[0004] Bulk polymerization has many advantages such as high single-pot yield and no need for distillation to recover solvents. Compared with solution polymerization, bulk polymerization has a simple process flow, low production cost, and more industrial development value. However, syndiotactic polystyrene has the characteristics of fast crystallization speed and good solubility resistance, so its solubility in styrene is very low, which makes the system quickly precipitate as soon as the polymer is produced during bulk polymerization. The smooth polymerization generally goes through the following process: homogeneous liquid → suspension → slurry → wet powder → dry powder. In these phase change processes, the precipitate of syndiotactic polystyrene can easily absorb monomers to form a swollen body, which adheres to the inner wall of the reactor and the stirring paddle. Once there is a stirring dead zone, or the crushing and dispersion refinement are not timely and sufficient, the swollen body will gradually accumulate and agglomerate to harden and form waste. It is not only difficult to be sheared and crushed, but also the stirring power will be extremely increased, so that polymerization is difficult to proceed. The problem of swelling and agglomeration of syndiotactic polystyrene in bulk polymerization is more serious than that in solution polymerization.

[0005] Therefore, it is necessary to solve the problem that low swelling and agglomeration and high single-pot yield cannot be achieved in the current production process of syndiotactic polystyrene. Summary of the invention

[0006] The purpose of the present invention is to overcome the problem that the current production process of syndiotactic polystyrene cannot take into account both low swelling and agglomeration and high single-pot yield, and to provide a method for preparing syndiotactic polystyrene.

[0007] The above-mentioned object of the present invention is achieved by the following technical solutions: A method for preparing syndiotactic polystyrene comprises the following steps: adding styrene, a main catalyst and a co-catalyst into a reactor, and performing bulk polymerization to obtain the syndiotactic polystyrene; The chemical formula of the main catalyst is RTiX 3 , wherein R is a substituted or unsubstituted phenanthryl, a substituted or unsubstituted anthracenyl, or a substituted or unsubstituted azulenyl, and X is independently a halogen atom, C 1-8 Alkyl, C 2-8 Alkenyl, C 3-8 Alkenyl, C 1-8 Alkoxy, aryl, C 1-8 Arylalkyl or C 1-9 Alkaryl; Specifically, the halogen atom is F, Cl or Br; 1-8 The alkyl group is methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl or octyl; 2-8 Alkenyl includes but is not limited to ethenyl, propenyl or butenyl; the C 3-8 Alkenyl includes but is not limited to allyl, allylbutyl or allylpentyl; the C 1-8 The alkoxy group includes but is not limited to methoxy, ethoxy or propoxy; the aryl group includes but is not limited to phenyl; the C 1-8 Aralkyl includes but is not limited to benzyl, phenethyl or phenylpropyl; the C 1-9 Alkaryl groups include, but are not limited to, 4-methyl-phenyl, 4-ethyl-phenyl or 4-propyl-phenyl.

[0008] It should be understood that what appears in the present invention is “C 1-8 " means that the number of carbon atoms is any integer between 1 and 8; "C 2-8 " refers to any integer between 2 and 8 carbon atoms; "C 3-8 " refers to any integer between 3 and 8 carbon atoms; "C 1-9 ” refers to any integer between 1 and 9 carbon atoms.

[0009] The reactor comprises a stirring tank and an agitator in the stirring tank, wherein the agitator comprises a first driving member, wherein the first driving member comprises a rotating output end, wherein the output end is eccentrically connected to a second driving member and a third driving member; or the first driving member has two rotating output ends, wherein each of the output ends is eccentrically connected to the second driving member and the third driving member; The output shaft of the second driving member is connected with a first stirring assembly, the first stirring assembly includes a first stirring rod and a first dispersion disk installed on the first stirring rod, and the first stirring rod is connected to the output shaft of the second driving member.

[0010] A second stirring assembly is connected to the output shaft of the third driving member, and the second stirring assembly includes a second stirring rod and a second dispersion disk installed on the second stirring rod, and the second stirring rod is connected to the output shaft of the third driving member; the diameter of the first dispersion disk is smaller than the diameter of the second dispersion disk.

[0011] The inventor of the present invention has found through research that by synthesizing syndiotactic polystyrene in bulk polymerization, low swelling and agglomeration and high single-pot yield can be taken into account through the combination of a specific main catalyst and a specific reactor, thereby greatly improving production efficiency and reducing production costs. The principle is that the self-rotation of the stirring assembly of the reactor produces a strong stirring effect of crushing, refining, dispersing and mixing, and the revolution of the first stirring assembly and the second stirring assembly is realized by respectively providing two stirring assemblies with a large-diameter second dispersion disk and a small-diameter first dispersion disk and setting a rotating output end, so that the reactor can be stirred without dead angles; on this basis, with a specific main catalyst, the polymerization rate can be controlled in a state that takes into account high activity and avoids implosion, so that the generation rate of the polymer swelling body is controllable, and can be fully broken up and refined by the strong stirring effect without dead angles in time, and the catalytic activity can still be stably released in the middle and late stages of polymerization to maintain efficient conversion.

[0012] If the reactor is not suitable, the stirring method is not suitable. For example, conventional stirring including double-screw blades, rotary blades, multi-layer scraper blades, etc. is used, which mainly strengthens the shear force and the scraping and cleaning ability of the inner wall, but cannot solve the problem of the stirring dead zone on the stirring shaft. Then the material is still easy to swell and adhere to the middle and bottom of the shaft to form large lumps. The horizontal self-cleaning reactor has the characteristics of complete self-cleaning. The E-type paddles of the two stirring shafts are meshed with each other to produce strong shear, and the stirring can act on the wall and the stirring shaft, so that there is no stirring dead zone inside the entire reactor cavity. Every place can be exposed to strong mechanical shear, which can effectively avoid the formation of adhesion and agglomeration. However, the horizontal kettle cannot be stirred at a high speed like the vertical kettle. After adding the material, it is difficult for the catalyst to be effectively and evenly mixed in the system, which makes the styrene conversion rate usually low.

[0013] If the main catalyst selected is not suitable, for example, the mainstream cyclopentadienyl-type titanocene catalyst in the industry is selected, the reaction characteristics are high-speed reaction in the early stage and slow polymerization in the middle and late stages, and the size of the polymerization activity is usually positively correlated with the speed of the polymerization rate. If the catalyst concentration is reduced to reduce the maximum polymerization rate to a level that avoids explosion and swelling, the polymerization rate and catalytic activity will decay rapidly in the later stage of polymerization, resulting in a very low overall conversion rate.

[0014] In addition, the preparation method of the present invention can also make the catalyst show high catalytic activity.

[0015] Preferably, the amount of the main catalyst is: per mole of styrene, 0.30×10 -5 ~1.1×10 -5 mmol of main catalyst.

[0016] Preferably, the molar ratio of the main catalyst to the co-catalyst is 1:(1-150). The molar ratio may specifically be 1:1, 1:5, 1:10, 1:20, 1:50, 1:100, 1:120 or 1:150.

[0017] Preferably, the main catalyst is at least one of azulenyltriallyltitanium, anthracenyltrimethyltitanium or phenanthrenyltribenzyltitanium. The main catalyst is further preferably azulenyltriallyltitanium.

[0018] Preferably, the preparation process of the main catalyst is as follows: add an aromatic compound and potassium bis(trimethylsilyl)amide to a solvent, react at 50-70°C for 7-9 hours; then add trimethylchlorosilane, react at room temperature (such as 20-30°C) for 1-3 hours; then add titanium tetrachloride, react at room temperature (such as 20-30°C) for 1-3 hours to obtain an intermediate product; mix the intermediate product with X-ONa, and then react at 70-90°C for 5-7 hours to obtain the main catalyst. The aromatic compound is at least one of phenanthrene, anthracene or azulene; X in the X-ONa is the same as X in the main catalyst.

[0019] Preferably, the co-catalyst comprises a first co-catalyst and a second co-catalyst in a molar ratio of 1: (1-150); the first co-catalyst is a borate catalyst; the second co-catalyst is at least one of an alkyl metal catalyst or a phenyl catalyst. The molar ratio may be 1:1, 1:5, 1:10, 1:20, 1:50, 1:100, 1:120 or 1:150.

[0020] More preferably, the borate catalyst is at least one of trityl-tetrakis(pentafluorophenyl)borate, N,N-dimethylaniline-tetrakis(pentafluorophenyl)borate or N,N-dimethylaniline-tetraphenylborate.

[0021] More preferably, the alkyl metal catalyst is at least one of triethylaluminum, diisobutylaluminum hydride or tetramethyltin.

[0022] More preferably, the phenyl-based catalyst is at least one of diphenylzinc or phenylsilane.

[0023] Preferably, the bulk polymerization is carried out at 60-100° C. (reaction temperature).

[0024] Preferably, the first stirring rod is provided with at least two first dispersion disks in parallel in the vertical direction, and the second stirring rod is provided with at least two second dispersion disks in parallel in the vertical direction; the vertical spacing between two adjacent first dispersion disks is 50~500mm, and the vertical spacing between two adjacent second dispersion disks is 50~500mm.

[0025] More preferably, the number of the first dispersing discs disposed on the first stirring rod is 2 to 4, and the number of the second dispersing discs disposed on the second stirring rod is 2 to 4.

[0026] Preferably, the first dispersing disk revolves around the rotation center of the first output end to form a motion trajectory of a first annular area, the first annular area is projected onto the cross section of the stirring tank, and the portion of the cross section of the stirring tank not covered by the first annular area is a first blank area; the outer peripheral edge of the second dispersing disk is close to the inner wall surface of the stirring tank, the rotation center of the second output end is colinear with the center line of the stirring tank, the second dispersing disk revolves around the center line of the stirring tank to form a motion trajectory of a second annular area, the second annular area is projected onto the cross section of the stirring tank, and the portion of the cross section of the stirring tank not covered by the second annular area is a second blank area; the second annular area covers the first blank area, and the first annular area covers the second blank area; The size of the reactor satisfies the following relationship: L 1 ≥D-2L 2 , Y≥G / 2 and Y≤L 2 -(G / 2-L 1 ); Among them, L 1 Represents the diameter of the first dispersion disk, L 2 represents the diameter of the second dispersing disk, D represents the inner diameter of the stirring tank, Y represents the distance between the center of the first circular area and the inner wall of the stirring tank, and G represents the outer diameter of the first circular area.

[0027] More preferably, the angular velocity of the revolution is 2.0-5.5 rad / s; the linear velocity of the first dispersion disk driven by the second driving member to rotate and the linear velocity of the second dispersion disk driven by the third driving member to rotate are both 4-12 m / s.

[0028] Preferably, the agitator further comprises a scraper for cleaning the inner wall of the agitator tank, wherein the scraper is eccentrically mounted on the second output end and is located on a side of the second agitator rod close to the inner wall of the agitator tank.

[0029] Preferably, the stirrer further comprises a thermometer for detecting the reaction temperature.

[0030] More preferably, the vertical distance between the lowermost ends of the second stirring assembly, the scraper and the thermometer and the bottom of the reactor is 3 to 15 mm.

[0031] More preferably, the shortest distance in the vertical direction between any of the first and second dispersion disks adjacent to each other in the horizontal direction is 1-5 mm.

[0032] More preferably, the horizontal distance between the thermometer and the first stirring paddle is 3-15 mm.

[0033] More preferably, the horizontal distance between the scraper and the second stirring paddle is 3-15 mm.

[0034] More preferably, the horizontal distance between the thermometer and the inner wall of the reactor is 1-5 mm.

[0035] More preferably, the minimum horizontal distance between the scraper and the inner wall of the reactor is 1-5 mm.

[0036] Preferably, the reactor comprises a stirring tank, and the stirring tank comprises a lower tank body and an upper tank body; the lower tank body is provided with a jacket, a jacket inlet and outlet, and a discharge port; the upper tank body is provided with a sight glass (for observing the internal situation of the reactor), a vent and a feeding port, and the agitator is located in the upper tank body.

[0037] A syndiotactic polystyrene, wherein the weight average molecular weight of the syndiotactic polystyrene is 3×10 5 ~5×10 5 g / mol; the main catalyst content in the syndiotactic polystyrene is 4~30ppm, and the main catalyst is the above-mentioned main catalyst.

[0038] Specifically, the process of the preparation method of syndiotactic polystyrene is as follows: first heat the lower tank of the reactor; then the lower tank of the reactor is connected to the valve outlet pipes of the styrene tank and the catalyst tank respectively through the sleeve, evacuate, and then introduce nitrogen to fill the cavity of the lower tank of the reactor, and evacuate again. After that, the lower tank of the reactor is adjusted to the set reaction temperature. Then, the valves of the styrene tank and the catalyst tank are opened in sequence, and styrene and catalyst are added. Then, the mixture is revolved at the set angular velocity to stir and mix, and then the rotation of the first dispersion disk and the second dispersion disk is respectively started while keeping the angular velocity of the revolution unchanged, so that the linear speed of the first dispersion disk and the second dispersion disk reaches 4-12m / s, and the reaction is carried out. After the reaction is completed, the temperature is increased to evacuate and devolatilize, and after the devolatilization is completed, a powdery product is obtained.

[0039] Compared with the prior art, the present invention has the following beneficial effects: The present invention synthesizes syndiotactic polystyrene by bulk polymerization, and can take into account low swelling and agglomeration and high single-reactor yield through the combination of a specific main catalyst and a specific reactor, thereby greatly improving production efficiency and reducing production costs. In addition, the preparation method of the present invention can also make the catalyst exhibit high catalytic activity. BRIEF DESCRIPTION OF THE DRAWINGS

[0040] Figure 1 Schematic diagram of the reactor used in the embodiments of the present invention.

[0041] Figure 2 a) is a first dispersion disk of a reactor used in an embodiment of the present invention, forming a first annular area, wherein a blank area with A as the center is a first blank area; Figure 2 b) is a second dispersion disk of the reactor used in the embodiment of the present invention, forming a second annular area, wherein the blank area with O as the center is the second blank area; Figure 2 c) is a schematic diagram of the overlap of the first circular ring area and the second circular ring area.

[0042] Figure 3 It is a schematic diagram of the structure of the agitator in the reactor used in the embodiment of the present invention.

[0043] In the accompanying drawings: 1, stirring tank; 2, agitator; 21, first driving member; 22, first output end; 23, second output end; 24, second driving member; 25, first stirring assembly; 251, first stirring rod; 252, first dispersion disk; 26, third driving member; 27, second stirring assembly; 271, second stirring rod; 272, second dispersion disk; 28, scraper; 211, driving gear; 212, first driven gear; 213, driven gear; 214, driving motor; 17, first connecting member; 18, first mounting plate; 19, second connecting member; 20, second mounting plate; 11, jacket; 12, jacket inlet and outlet; 13, discharge port; 14, thermometer; 15, sight glass; 16, vent and feeding port; 101, lower tank body; 102, upper tank body. DETAILED DESCRIPTION

[0044] In order to more clearly and completely describe the technical solution of the present invention, the present invention is further described in detail by specific embodiments below. It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention. Various changes can be made within the scope of the rights of the present invention. For example, the size settings of the components in the embodiments are only for explaining the present invention and are not used as specific limitations.

[0045] The structure of the reactor used in each embodiment of the present invention is as follows Figure 1 , Figure 3 The reactor comprises a stirring tank 1, which comprises a lower tank body 101 and an upper tank body 102. The lower tank body 101 is provided with a jacket 11, a jacket inlet and outlet 12 and a discharge port 13; the upper tank body 102 comprises a sight glass 15, a vent and a feed port 16, and an agitator 2 installed in the upper tank body 102. The agitator 2 comprises a first driving member 21, which has at least a first rotating output end 22 and a second output end 23; the first output end 22 is eccentrically connected to a second driving member 24, and the output shaft of the second driving member 24 is connected to a first stirring assembly 25. Component 25 includes a first stirring rod 251 and a first dispersion disk 252 installed on the first stirring rod 251, and the first stirring rod 251 is connected to the output shaft of the second driving component 24; the second output end 23 is eccentrically connected to the third driving component 26, and the output shaft of the third driving component 26 is connected to the second stirring component 27, the second stirring component 27 includes a second stirring rod 271 and a second dispersion disk 272 installed on the second stirring rod 271, and the second stirring rod 271 is connected to the output shaft of the third driving component 26; the diameter of the first dispersion disk 252 is smaller than the diameter of the second dispersion disk 272.

[0046] In this embodiment, the first output end 22 drives the second driving member 24 eccentrically connected thereto to rotate, and the second driving member 24 drives the entire first stirring assembly 25 to rotate, so that the first stirring assembly 25 can rotate under the action of the second driving member 24, and the first stirring assembly 25 revolves under the drive of the first output end 22, and the second output end 23 drives the third driving member 26 eccentrically connected thereto to rotate, and the third driving member 26 drives the entire second stirring assembly 27 to rotate, so that the second stirring assembly 27 can rotate under the action of the third driving member 26, and the second stirring assembly 27 revolves under the drive of the second output end 23. The rotation of the first stirring assembly 25 and the second stirring assembly 27 produces a strong stirring effect of crushing, refining, dispersing, and mixing, and by respectively providing a large-diameter second dispersion disk 272 and a small-diameter first dispersion disk 252, in conjunction with the revolution of the first stirring assembly 25 and the revolution of the second stirring assembly 27, the stirring tank 1 can be stirred without dead angles.

[0047] It should be noted that the first driving member 21 includes a driving gear 211, a first driven gear 212, a second driven gear 213 and a driving motor 214. The first driven gear 212 and the second driven gear 213 are respectively meshed with the driving gear 211 and are distributed on both sides of the driving gear 211. The driving gear 211 is connected to the output shaft of the driving motor 214. The output shaft of the driving motor 214 drives the driving gear 211 to rotate. The driving gear 211 drives the first driven gear 212 and the second driven gear 213 to rotate. During the rotation, the first driven gear 212 and the second driven gear 213 drive the transmission shafts respectively connected to their shaft holes to rotate. One of the transmission shafts is a first output end 22, and the other is a second output end 23. The first output end 22 is connected to a first L-shaped connecting member 17. A first mounting plate 18 is installed on the first connecting member 17. A second driving member 24 is installed on the first mounting plate 18. The second driving member 24 can be a second motor. A thermometer 14 can also be connected to the first mounting plate 18. The second output end 23 is connected to a second L-shaped connecting member 19, a second mounting plate 20 is mounted on the second connecting member 19, a third driving member 26 is mounted on the second mounting plate 20, and the third driving member 26 can be a third motor. The mixing tank 1 can be designed with a jacket 11, and the mixing tank 1 is provided with a jacket inlet and outlet 12 and a discharge port 13. It should also be pointed out that "connection" is "fixed connection" and "installation" is "fixed installation".

[0048] It should be noted that the parameters of the reactor can be as follows: the inner diameter D of the stirring tank 1 is 30 cm. The diameter L of the first dispersion disk 252 is 1 The diameter L of the second dispersion disk 272 may be 7.2 cm. 2It can be 12cm. The minimum distance between the axis center of the first stirring rod 251 and the inner wall of the stirring tank 1 is 4.5cm, the distance from the center point A of the revolution of the first stirring component 25 to the inner wall of the stirring tank 1 is Y=10cm, and the distance between the first dispersing disk 252 and the thermometer 14 is 3mm. The minimum distance between the axis center of the second stirring rod 271 and the inner wall of the reactor is 6cm, the scraper 28 is 3mm away from the inner wall of the reactor, and the shortest distance between the second dispersing disk 272 and the scraper 28 can be 3mm. The centers of the driving gear, the first driven gear and the second driven gear are all on the diameter line passing through the center of the stirring tank 1. The diameter of the second driven gear is 2cm, and the center of the second driven gear is the center point O of the stirring tank 1. The diameter of the first driven gear is 2cm, and the distance from the center of the first driven gear to the inner wall of the stirring tank 1 is 10cm. The diameter of the driving gear is 3cm, and the distance from the center of the driving gear to the inner wall of the stirring tank 1 is 12.5cm.

[0049] In addition, the stirring tank 1 is also provided with a sight glass 15, a vent 16 and a feed port 16, and the stirrer 2 also includes a scraper 28 for cleaning the inner wall of the stirring tank 1. The scraper 28 is eccentrically mounted on the second output end 23 and is located on the side of the second stirring rod 271 close to the inner wall of the stirring tank 1. The scraper 28 is closer to the inner wall of the stirring tank 1 than the edge of the second dispersion disk 272. At this time, the minimum distance between the axis center of the second stirring rod 271 and the inner wall of the stirring tank 1 is 6 cm, the shortest distance between the second dispersion disk 272 and the scraper 28 is 3 mm, and the distance between the scraper 28 and the inner wall of the stirring tank 1 is 3 mm.

[0050] Among them, at least two first dispersion disks 252 are arranged in parallel in the vertical direction of the first stirring rod 251, and at least two second dispersion disks 272 are arranged in parallel in the vertical direction of the second stirring rod 271. The vertical distance between two adjacent first dispersion disks 252 is 100 mm, and the vertical distance between two adjacent second dispersion disks 272 is 100 mm.

[0051] The first driving member 21 drives the first output end 22 and the second output end 23 to revolve, the second driving member 24 drives the first dispersion disk 252 to rotate, and the third driving member 26 drives the second dispersion disk 272 to rotate.

[0052] In addition, the first dispersing disk 252 revolves around the rotation center of the first output end 22 to form a motion trajectory of the first annular region. The outer diameter G of the first annular region is 18.4 cm. The first annular region is projected onto the cross section of the mixing tank 1. The portion of the cross section of the mixing tank 1 not covered by the first annular region is the first blank area. Figure 2a); the outer peripheral edge of the second dispersing disk 272 is close to the inner wall surface of the stirring tank 1, the rotation center of the second output end 23 is colinear with the center line of the stirring tank 1, and the second dispersing disk 272 revolves around the center line of the stirring tank 1 to form a motion trajectory of the second annular area, and the second annular area is projected onto the cross section of the stirring tank 1. The part of the cross section of the stirring tank 1 not covered by the second annular area is the second blank area, see Figure 2 b); the second annular area covers the first blank area, and the first annular area covers the second blank area, see Figure 2 c). The outer edge of the second dispersing disk 272 is close to the inner wall of the stirring tank 1, which means that the distance between the outer edge of the second dispersing disk 272 and the inner wall of the stirring tank 1 is small enough. The smaller the distance, the better, while keeping the second dispersing disk 272 from rubbing against the inner wall of the stirring tank 1.

[0053] It should be noted that those skilled in the art can adaptably adjust the size of the stirring tank and each component according to the magnitude of the reaction, which is a conventional technical means in the art. The specific parameters of the reactor listed above are only for better explanation of the present invention and are not intended to be specific limitations.

[0054] Some of the reagents selected in the embodiments and comparative examples of the present invention are described as follows: Azulenyltriallyltitanium (denoted as A1#): Homemade, the process is as follows: In a glove box, add 1mmol of azulene and 1mmol of potassium bis(trimethylsilyl)amide to 5mL of tetrahydrofuran, stir and react at 60°C for 8h, then add 1mmol of trimethylsilyl chloride and stir at room temperature for 2h, then add 1mmol of titanium tetrachloride and stir at room temperature for 2h to obtain a brown solid-liquid mixture. After draining the solvent, wash three times with tetrahydrofuran (5mL of tetrahydrofuran each time), drain the solvent under reduced pressure to obtain an intermediate product; add 5mL of toluene and 1mmol of sodium allyl alcohol to the intermediate product, react at 80°C for 6h, drain the solvent, wash the yellow solid with n-hexane three times (5mL of n-hexane each time), then drain under reduced pressure to obtain a yellow powder, which is azulenyltriallyltitanium.

[0055] The NMR characterization results of azulenyltriallyltitanium are: δ=7.12-7.21, 4H; δ=7.39-7.49, 1H; δ=7.72, 1H; δ=8.04-8.11, 2H; δ=5.99, 3H; δ=5.29, 3H; δ=5.16, 3H; δ=1.75, 6H; elemental analysis target molecular formula C 19 H 23 Ti (%) = C: 76.38%, H: 7.70%. This indicates the successful synthesis of azulenyl triallyltitanium, whose structural formula is as follows: .

[0056] Anthracene trimethyl titanium (denoted as A2#): homemade, the process is as follows: In a glove box, 1mmol anthracene and 1mmol potassium bis(trimethylsilyl)amide were added to 5mL tetrahydrofuran, stirred at 60°C for 8h, then 1mmol trimethylsilyl chloride was added and stirred at room temperature for 2h, then 1mmol titanium tetrachloride was added and stirred at room temperature for 2h to obtain a brown solid-liquid mixture, after filtering out the filtrate, tetrahydrofuran was added for washing three times (5mL of tetrahydrofuran was used each time), and the solvent was drained under reduced pressure to obtain an intermediate product; 5mL of toluene and 1mmol of sodium methoxide were added to the intermediate product, and the reaction was carried out at 80°C for 6h, and the solvent was drained, and the yellow solid was washed three times with n-hexane (5mL of n-hexane was used each time), and then drained under reduced pressure to obtain a yellow powder, which is anthracene trimethyltitanium.

[0057] The NMR characterization results of anthracenyltrimethyltitanium are: δ=8.40, 2H; δ=7.98, 4H; δ=7.44, 4H; δ=1.20, 12H; the elemental analysis target molecular formula is C 17 H 22 Ti (%) = C: 72.06%, H: 8.81%. This indicates the successful synthesis of anthracene trimethyl titanium, and its structural formula is as follows: .

[0058] Phenanthryltribenzyltitanium (denoted as A3#): homemade, the process is as follows: In a glove box, 1mmol of phenanthrene and 1mmol of potassium bis(trimethylsilyl)amide were added to 5mL of tetrahydrofuran, and the mixture was stirred at 60°C for 8h. Then, 1mmol of trimethylsilyl chloride was added and stirred at room temperature for 2h. Then, 1mmol of titanium tetrachloride was added and stirred at room temperature for 2h to obtain a brown solid-liquid mixture. After filtering and removing the filtrate, the mixture was washed three times with tetrahydrofuran (5mL of tetrahydrofuran each time), and the solvent was drained under reduced pressure to obtain an intermediate product. 5mL of toluene and 1mmol of sodium benzyl alcohol were added to the intermediate product, and the mixture was reacted at 80°C for 6h. The solvent was drained, and the yellow solid was washed three times with n-hexane (5mL of n-hexane each time), and then drained under reduced pressure to obtain a yellow powder, which is phenanthryltribenzyltitanium.

[0059] The NMR characterization results of phenanthryltribenzyltitanium are: δ=8.76-8.80, 2H; δ=8.15, 2H; δ=7.98, 2H; δ=7.88-7.92, 2H; δ=7.78, 2H; δ=7.20, 15H; δ=2.40, 6H; elemental analysis target molecular formula C 35 H 31Ti (%) = C: 84.25%, H: 6.22%. This indicates the successful synthesis of anthracene trimethyl titanium, and its structural formula is as follows: .

[0060] Diphenyl zinc (denoted as B1#): commercially available; Tetraphenyltin (denoted as B2#): commercially available; N,N-dimethylaniline-tetrakis(pentafluorophenyl)borate (denoted as B3#): CAS No. 118612-00-3, commercially available; Trityl tetrakis(pentafluorophenyl)borate (denoted as B4#): CAS No. 136040-19-2, commercially available; Pentamethylcyclopentadienyltrimethoxytitanium: commercially available; Triisobutylaluminum: commercially available; Example 1 This embodiment provides a method for preparing syndiotactic polystyrene, comprising the following steps: 1) The number of the first dispersion disk and the number of the second dispersion disk are both 2. First, heat transfer oil is introduced to heat the reactor body at 100°C, and vacuum is applied for 30 minutes. Then, nitrogen is introduced to fill the cavity of the reactor body, and vacuum is applied again, and this is repeated three times.

[0061] 2) Then, the reactor body was adjusted to the set reaction temperature (see Table 1), and 6000 g of styrene, 1 mL of a toluene solution of diphenylzinc (containing 14.4 mmol of diphenylzinc), 1 mL of a toluene solution of N,N-dimethylaniline-tetrakis(pentafluorophenyl)borate (containing 0.27 mmol of N,N-dimethylaniline-tetrakis(pentafluorophenyl)borate) and 1 mL of a toluene solution of azulenyltriallyltitanium (the molar amount of azulenyltriallyltitanium is shown in Table 1) were added in sequence through the feed port, and the revolution was started at a certain speed (see Table 1), stirred for 1 min, and then the rotation of the first dispersing disk and the second dispersing disk was started respectively while keeping the revolution unchanged, so that the linear speeds of the first dispersing disk and the second dispersing disk both reached the set linear speed (see Table 1), and the reaction was continued for 1 h.

[0062] 3) After the reaction is completed, the temperature of the heat transfer oil in the jacket is raised to 140°C and vacuum devolatilization is performed for 1 hour. After the devolatilization is completed, the discharge valve at the bottom of the kettle is opened to obtain a dry product, which is sieved through a 18-mesh sieve to obtain syndiotactic polystyrene.

[0063] Embodiment 2~6 Examples 2 to 6 provide a series of methods for preparing syndiotactic polystyrene, the differences between which and Example 1 are shown in Table 1.

[0064] Table 1

[0065] Comparative Example 1 This comparative example provides a method for preparing syndiotactic polystyrene, which is different from Example 1 in that the main catalyst A1# is replaced with an equimolar amount of pentamethylcyclopentadienyltrimethoxytitanium.

[0066] Comparative Example 2 This comparative example provides a method for preparing syndiotactic polystyrene, which is different from Example 1 in that the main catalyst A1# is replaced by an equimolar amount of pentamethylcyclopentadienyltrimethoxytitanium; and the co-catalysts (B1# and B3#) are replaced by an equimolar amount of triisobutylaluminum.

[0067] Comparative Example 3 This comparative example provides a method for preparing syndiotactic polystyrene, which is different from Example 1 in that the agitator of the reactor used is only provided with a first dispersing disk, and no second dispersing disk is provided.

[0068] Comparative Example 4 This comparative example provides a method for preparing syndiotactic polystyrene, which is different from Example 1 in that the reactor is replaced with a conventional uniaxial stirred kettle (vertical straight cylindrical reactor, diameter 30 cm, the stirring paddle is an anchor paddle, the paddle diameter is 29.4 cm (so that the outer edge of the paddle is 3 mm away from the inner wall of the kettle), the paddle height is 10 cm), and the stirring linear speed is 8 m / s.

[0069] Comparative Example 5 This comparative example provides a method for preparing syndiotactic polystyrene, which is different from Example 1 in that the reactor is replaced with a reactor with a double-screw propeller (see the accompanying drawings and Figure 1 , the distance between the outer edge of the double-screw propeller and the inner wall of the reactor is 3 mm); the linear speed of stirring is 8 m / s.

[0070] Performance Testing The syndiotacticity, weight average molecular weight and number average molecular weight of the syndiotactic polystyrene prepared by the preparation methods of each embodiment and comparative example were measured, and the styrene conversion rate, swelling body content and catalyst activity (catalyst activity refers to the mass of syndiotactic polystyrene generated per mole of catalyst) were calculated. The test method is as follows: (1) The syndiotacticity was characterized by NMR carbon spectroscopy, the instrument model was Bruker DMX 500 Hz, and the test sample was dissolved in deuterated o-dichlorobenzene. The chemical shift of the syndiotactic structure was 145.1-145.3 ppm, and the chemical shift of the random structure was 144.8-146.0 ppm. The syndiotacticity = syndiotactic structure peak area / (random structure + syndiotactic structure) peak area.

[0071] (2) Molecular weight: Characterized by gel permeation chromatography (GPC), instrument manufacturer Agilent, model PL-GPC220, differential detector, chromatographic column using three PLgel 10um MIXED-B LS 300*7.5mm in series, mobile phase: 1,2,4-trichlorobenzene, temperature: 150℃, flow rate: 1mL / min. The standard curve of the GPC test is determined by using polystyrene with narrow molecular weight distribution as the standard sample, and the weight average relative molecular weight (Mw) and number average relative molecular weight (Mn) of the polymer are calculated. The sample syndiotactic polystyrene sample to be tested is dissolved in 1,2,4-trichlorobenzene, the concentration is configured to 2-5 mg / mL, and filtered through a 450nm organic filter to remove insoluble impurities.

[0072] (3) Monomer conversion rate = polystyrene mass / styrene feed mass × 100%.

[0073] (4) Swelling body content = swelling body mass / styrene feed mass × 100%, wherein the dried product is passed through a 18-mesh (mesh diameter 1 mm) vibrating sieve. The powder passing through the sieve is polystyrene, and the powder retained on the sieve is the swelling body.

[0074] (5) Catalyst activity = product mass / molar amount of main catalyst The test results are shown in Table 2.

[0075] Table 2 Test results of syndiotactic polystyrene properties of various embodiments and comparative examples Test Results Regularity Styrene conversion rate (%) Swelling body content (%) Weight average molecular weight (g / mol) Number average molecular weight (g / mol) Catalyst activity (g sPS / mol Ti) Example 1 100% 95 0.1 459000 219000 <![CDATA[3.17×10 7 ]]> Example 2 100% 99.5 0.1 345000 148000 <![CDATA[1.00×10 7 ]]> Example 3 100% 99 0.1 386000 169000 <![CDATA[1.98×10 7 ]]> Example 4 100% 93.5 0.1 468000 224000 <![CDATA[3.12×10 7 ]]> Example 5 100% 94 0.1 463000 225000 <![CDATA[3.13×10 7 ]]> Example 6 100% 94.5 0.1 457000 221000 <![CDATA[3.15×10 7 ]]> Comparative Example 1 100% 20 0.1 405000 173000 <![CDATA[0.67×10 7 ]]> Comparative Example 2 100% 14 0.1 397000 177000 <![CDATA[0.47×10 7 ]]> Comparative Example 3 100% 75 20 473000 208000 <![CDATA[2.50×10 7 ]]> Comparative Example 4 / 0 90 / / / Comparative Example 5 100% 70 22 466000 217000 <![CDATA[2.33×10 7 ]]>

[0076] From Table 2, we can see that: The syndiotactic polystyrene of Examples 1 to 6 all had a syndiotacticity of 100%, a conversion rate of more than 93%, a swelling body content of less than 0.1%, a weight average molecular weight of 345,000 to 468,000 g / mol, a number average molecular weight of 148,000 to 225,000 g / mol, and a catalyst activity of up to 3.17×10 7 g sPS / mol Ti, indicating that the preparation method of the present invention has a good balance between low swelling and agglomeration and high single-pot yield in the process of producing syndiotactic polystyrene.

[0077] Comparative Example 1 uses the existing conventional main catalyst pentamethylcyclopentadienyl trimethoxytitanium, and the styrene conversion rate of its preparation method is low. Comparative Example 2 uses the existing conventional metallocene catalyst system, and the styrene conversion rate of its preparation method is low. And it can be seen from Comparative Example 1, Comparative Example 1 and Comparative Example 2 that the catalyst activity of the preparation method of the present invention is significantly higher.

[0078] The reactor of Comparative Example 3 was not equipped with a second dispersion disk, and its swelling body content increased significantly to 20%, and the conversion rate was reduced to 75%, and the catalytic activity was also reduced to 2.50x10 7 g sPS / mol Ti. In Comparative Example 4, the reactor was replaced with a conventional vertical uniaxial stirred kettle of similar size, and the system formed a large area of ​​swollen body, and almost no powder product was obtained. In Comparative Example 5, the reactor was replaced with a double-screw ribbon stirring blade, and 22% of the swollen body still appeared, the conversion rate was reduced to 70%, and the catalytic activity was also low.

[0079] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A method for preparing syndiotactic polystyrene, characterized in that: The method comprises the following steps: adding styrene, a main catalyst and a co-catalyst into a reactor to carry out bulk polymerization to obtain the syndiotactic polystyrene; The chemical formula of the main catalyst is RTiX3, wherein R is a substituted or unsubstituted phenanthryl, a substituted or unsubstituted anthracenyl, or a substituted or unsubstituted azulenyl, and X is independently a halogen atom, C 1-8 Alkyl, C 1-8 Alkenyl, C 1-8 Alkenyl, C 1-8 Alkoxy, aryl, C 1-8 Arylalkyl or C 1-9 Alkaryl; The reactor comprises a stirring tank (1) and an agitator (2) located in the stirring tank (1), the agitator (2) comprising a first driving member (21), the first driving member (21) comprising a rotating output end, the output end being eccentrically connected to a second driving member (24) and a third driving member (26); or the first driving member (21) has two rotating output ends, each of the output ends being eccentrically connected to the second driving member (24) and the third driving member (26); The output shaft of the second driving member (24) is connected to a first stirring assembly (25), the first stirring assembly (25) comprising a first stirring rod (251) and a first dispersion disc (252) mounted on the first stirring rod (251), the first stirring rod (251) being connected to the output shaft of the second driving member (24); The output shaft of the third driving member (26) is connected to a second stirring assembly (27), the second stirring assembly (27) comprising a second stirring rod (271) and a second dispersion disc (272) mounted on the second stirring rod (271), the second stirring rod (271) being connected to the output shaft of the third driving member (26); The diameter of the first dispersion disk (252) is smaller than the diameter of the second dispersion disk (272).

2. The preparation method according to claim 1, characterized in that: The dosage of the main catalyst is: per mole of styrene, add 0.30×10 -5 ~1.1×10 -5 mmol of main catalyst.

3. The preparation method according to claim 1, characterized in that: The main catalyst is at least one of azulenyltriallyltitanium, anthracenyltrimethyltitanium or phenanthrenyltribenzyltitanium.

4. The preparation method according to claim 1, characterized in that: The molar ratio of the main catalyst to the co-catalyst is 1:(1-150); the co-catalyst includes a first co-catalyst and a second co-catalyst in a molar ratio of 1:(1-150); the first co-catalyst is a borate catalyst; and the second co-catalyst is at least one of an alkyl metal catalyst or a phenyl catalyst.

5. The preparation method according to claim 1, characterized in that: The bulk polymerization is carried out at 60-100°C.

6. The preparation method according to claim 1, characterized in that: The first stirring rod (251) is provided with at least two first dispersion discs (252) in parallel along a vertical direction, and the second stirring rod (271) is provided with at least two second dispersion discs (272) in parallel along a vertical direction, and the vertical distance between two adjacent first dispersion discs (252) is 50-500 mm, and the vertical distance between two adjacent second dispersion discs (272) is 50-500 mm.

7. The preparation method according to claim 1, characterized in that: The first dispersing disk (252) revolves around the rotation center of the first output end (22) to form a motion trajectory of a first annular area; the first annular area is projected onto the cross section of the stirring tank (1); the portion of the cross section of the stirring tank (1) not covered by the first annular area is a first blank area; the outer peripheral edge of the second dispersing disk (272) is close to the inner wall surface of the stirring tank (1); the rotation center of the second output end (23) is colinear with the center line of the stirring tank (1); the second dispersing disk (272) revolves around the center line of the stirring tank (1) to form a motion trajectory of a second annular area; the second annular area is projected onto the cross section of the stirring tank (1); the portion of the cross section of the stirring tank (1) not covered by the second annular area is a second blank area; the second annular area covers the first blank area, and the first annular area covers the second blank area; The size of the reactor satisfies the following relationship: L1≥D-2L2, Y≥G / 2 and Y≤L2-(G / 2-L1); Wherein, L1 represents the diameter of the first dispersion disk (252), L2 represents the diameter of the second dispersion disk (272), D represents the inner diameter of the stirring tank (1), Y represents the distance between the center A of the first circular area and the inner wall of the stirring tank (1), and G represents the outer diameter of the first circular area.

8. The preparation method according to claim 7, characterized in that: The angular velocity of the revolution is 2.0-5.5 rad / s; the linear velocity of the first dispersion disk (252) driven by the second driving member (24) to rotate and the linear velocity of the second dispersion disk (272) driven by the third driving member (26) to rotate are both 4-12 m / s.

9. The preparation method according to claim 1, characterized in that: The agitator further comprises a scraper (28) for cleaning the inner wall of the agitation tank (1); the scraper (28) is eccentrically mounted on the second output end (23) and is located on a side of the second agitation rod (271) close to the inner wall of the agitation tank (1).

10. A syndiotactic polystyrene, characterized in that: The weight average molecular weight of the syndiotactic polystyrene is 3×10 5 ~5×10 5 g / mol; the main catalyst content in the syndiotactic polystyrene is 4~30ppm, and the main catalyst is the main catalyst according to any one of claims 1 to 9.

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