Styrene-based polymer, preparation method thereof and brominated styrene-based polymer

Abstract

The invention relates to the technical field of high polymer material synthesis and preparation, and discloses a styryl polymer, a preparation method thereof and a brominated styryl polymer, the styryl polymer comprises a styrene structural unit and a 1, 1-diphenylethylene structural unit; the molecular weight distribution index of the styrene-based polymer is 1 to 1.1; the number-average molecular weight of the styrene-based polymer is 2,000 to 1,1,000 g / mol. The styryl polymer has the characteristics of low number-average molecular weight and narrow molecular weight distribution, and the brominated styryl polymer obtained by bromination has excellent fluidity, thermal stability and color stability. The preparation method provided by the invention can highly control the structure, molecular weight and molecular weight distribution of the styrene-based polymer.

Description

Technical Field

[0001] The invention relates to the technical field of polymer material synthesis and preparation, and in particular to a styrene-based polymer and a preparation method thereof, and a brominated styrene-based polymer. Background Art

[0002] Brominated polystyrene has good thermal stability, good dispersibility and miscibility in polymers, easy processing, no surface frost, no migration and no static electricity, and will not penetrate biofilms. It is a highly efficient and environmentally friendly flame retardant and is widely used in engineering plastics such as nylon, PBT, PET, PC, etc.

[0003] There are two production processes for brominated styrene polymers: the first process is to brominate styrene first, and then polymerize to generate brominated styrene polymers; the second process is to first polymerize styrene to generate polystyrene, and then brominate to generate brominated styrene polymers. The advantage of the first process is that the polybrominated styrene product generated has almost no chain breakage, excellent thermal stability, high decomposition temperature, and very good appearance, but the synthesis process is very complicated, the production cost is high, the production cycle is long, and it is not conducive to large-scale industrialization. The second process has a short synthesis route, low production cost, and is suitable for large-scale industrial production, but it has high requirements on the molecular structure of polystyrene. Most of the polystyrene raw materials used in existing brominated polystyrene are prepared by free radical polymerization. There are many head-to-head structures in the polystyrene molecular chain, the molecular weight is difficult to control, and the relative molecular mass distribution is wide. The relative molecular mass distribution of the obtained brominated polystyrene product is wide. During processing, the molecules with large relative molecular mass have not completely melted, and the molecules with small relative molecular mass have begun to decompose under heat, resulting in a high melting point and low decomposition temperature of brominated polystyrene.

[0004] Therefore, it is of great significance to develop polystyrene with controllable molecular weight, narrow molecular weight distribution, and styrene connected head to tail in the molecular chain, to solve the problem of key raw material sources for brominated polystyrene, and to realize the industrialization of high-performance brominated polystyrene. Summary of the invention

[0005] The purpose of the present invention is to overcome the problem that the polystyrene in the prior art has a high number average molecular weight and a wide molecular weight distribution, and cannot meet the special requirements of high-performance brominated styrene for polystyrene raw materials, and to provide a styrene-based polymer and a preparation method thereof and a brominated styrene-based polymer, wherein the styrene-based polymer has the characteristics of a low number average molecular weight and a narrow molecular weight distribution, and the brominated styrene-based polymer obtained by bromination has excellent fluidity, thermal stability and color stability. The preparation method of the present invention can highly control the number average molecular weight and molecular weight distribution of the styrene-based polymer.

[0006] In order to achieve the above object, the present invention provides a styrene-based polymer in a first aspect, wherein the styrene-based polymer comprises a styrene structural unit and a 1,1-diphenylethylene structural unit;

[0007] The molecular weight distribution index of the styrene-based polymer is 1-1.1;

[0008] The number average molecular weight of the styrene-based polymer is 2000-11000 g / mol.

[0009] A second aspect of the present invention provides a method for preparing a styrene-based polymer, wherein the preparation method comprises:

[0010] (1) in the presence of a protective gas, 1,1-diphenylethylene, an anionic polymerization initiator and an organic solvent are mixed to obtain a first mixed solution, and under polymerization reaction conditions, the first mixed solution is subjected to a first polymerization reaction to obtain a solution containing a prepolymer; wherein the total water content of the 1,1-diphenylethylene and the organic solvent is less than or equal to 1 ppm;

[0011] (2) adding styrene monomer to the solution containing the prepolymer obtained in step (1) under low temperature conditions and in the presence of a protective gas to carry out a second polymerization reaction; wherein the water content in the styrene monomer is less than or equal to 1 ppm; and the content of the polymerization inhibitor in the styrene monomer is less than or equal to 1 ppm;

[0012] (3) after the second polymerization reaction is completed, a terminator is used to terminate the reaction to obtain a styrene-based polymer solution, and a styrene-based polymer is obtained through post-treatment;

[0013] The molar ratio of the terminator to the anionic polymerization initiator is 1-2:1.

[0014] The third aspect of the present invention provides a styrene-based polymer obtained by the above preparation method.

[0015] A fourth aspect of the present invention provides a brominated styrene-based polymer, wherein the brominated styrene-based polymer is obtained by brominating the above-mentioned styrene-based polymer.

[0016] Through the above technical scheme, the styrene-based polymer and the preparation method thereof and the brominated styrene-based polymer provided by the present invention have the following beneficial effects.

[0017] The styrene-based polymer of the present invention has the characteristics of low number average molecular weight and narrow molecular weight distribution. The brominated styrene-based polymer obtained by bromination has excellent thermal stability, fluidity and color stability.

[0018] The present invention introduces 1,1-diphenylethylene into the first polymerization reaction by adopting anionic polymerization, which can reduce the initiation rate of the second polymerization reaction. Since the characteristics of anionic polymerization are fast initiation rate and slow molecular chain growth, the method can avoid the problem of wide molecular weight distribution caused by the time difference of adding styrene monomer; at the same time, the impurity content in 1,1-diphenylethylene, organic solvent and styrene monomer of the present invention is low, ensuring that all the added initiators participate in the polymerization reaction, thereby highly controlling the number average molecular weight and molecular weight distribution of the styrene-based polymer. DETAILED DESCRIPTION

[0019] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

[0020] The first aspect of the present invention provides a styrene-based polymer, wherein the styrene-based polymer comprises a styrene structural unit and a 1,1-diphenylethylene structural unit;

[0021] The molecular weight distribution index of the styrene-based polymer is 1-1.1;

[0022] The number average molecular weight of the styrene-based polymer is 2000-11000 g / mol.

[0023] The styrene-based polymer of the present invention has the characteristics of low number average molecular weight and narrow molecular weight distribution, and the brominated styrene-based polymer obtained by bromination has excellent thermal stability, fluidity and color stability. When the styrene-based polymer meets the above range, the brominated styrene-based polymer has good fluidity; at the same time, when the number average molecular weight distribution of the styrene-based polymer meets the above range, the prepared brominated styrene-based polymer has good quality uniformity and stable color.

[0024] Furthermore, the number average molecular weight of the styrene-based polymer is 3000-8000 g / mol.

[0025] Furthermore, the number average molecular weight of the styrene-based polymer is 4000-7000 g / mol.

[0026] Furthermore, the molecular weight distribution index of the styrene-based polymer is 1-1.05.

[0027] Furthermore, the molecular weight distribution index of the styrene-based polymer is 1-1.03.

[0028] According to the present invention, based on the total mass of the styrene-based polymer, the content of the 1,1-diphenylethylene structural unit is 1.6-9wt%.

[0029] In the present invention, when the content of 1,1-diphenylethylene structural units meets the above range, the polymerization rate of styrene can be better reduced and the molecular weight distribution of polystyrene can be controlled.

[0030] Furthermore, based on the total mass of the styrene-based polymer, the content of the 1,1-diphenylethylene structural unit is 2.2-6 wt %.

[0031] Furthermore, based on the total mass of the styrene-based polymer, the content of the 1,1-diphenylethylene structural unit is 2.5-4.5 wt %.

[0032] According to the present invention, the yellowness index of the styrene-based polymer is from -6 to 2.

[0033] In the present invention, when the yellowness index of the styrene-based polymer meets the above range, the yellowness index of the prepared brominated polystyrene is lower.

[0034] Furthermore, the yellowness index of the styrene-based polymer is from -6 to 0.

[0035] Furthermore, the yellowness index of the styrene-based polymer is from -6 to -2.

[0036] A second aspect of the present invention provides a method for preparing a styrene-based polymer, wherein the preparation method comprises:

[0037] (1) in the presence of a protective gas, 1,1-diphenylethylene, an anionic polymerization initiator and an organic solvent are mixed to obtain a first mixed solution, and under polymerization reaction conditions, the first mixed solution is subjected to a first polymerization reaction to obtain a solution containing a prepolymer; wherein the total water content of the 1,1-diphenylethylene and the organic solvent is less than or equal to 1 ppm;

[0038] (2) adding styrene monomer to the solution containing the prepolymer obtained in step (1) under low temperature conditions and in the presence of a protective gas to carry out a second polymerization reaction; wherein the water content in the styrene monomer is less than or equal to 1 ppm; and the content of the polymerization inhibitor in the styrene monomer is less than or equal to 1 ppm;

[0039] (3) after the second polymerization reaction is completed, a terminator is used to terminate the reaction to obtain a styrene-based polymer solution, and a styrene-based polymer is obtained through post-treatment;

[0040] The molar ratio of the terminator to the anionic polymerization initiator is 1-2:1.

[0041] In the present invention, 1,1-diphenylethylene is introduced into the first polymerization reaction, which can reduce the initiation rate of the second polymerization reaction. Since the conventional anionic polymerization is characterized by a fast initiation rate and slow molecular chain growth, the present method can avoid the problem of wide molecular weight distribution caused by the time difference of adding styrene monomers. At the same time, the impurity content in 1,1-diphenylethylene, organic solvent and styrene monomer of the present invention is low, ensuring that all the added initiators participate in the polymerization reaction, thereby highly controlling the number average molecular weight and molecular weight distribution of the styrene-based polymer.

[0042] In the present invention, the protective gas is nitrogen and / or argon. Preferably, the purity of the protective gas is not less than 99.999%.

[0043] In the present invention, the water content in the 1,1-diphenylethylene, the organic solvent and the styrene monomer is measured by a Karl Fischer titrator. When the Karl Fischer titrator cannot detect a value, it can be understood that the total water content in the 1,1-diphenylethylene and the organic solvent is less than or equal to 1 ppm; the water content in the styrene monomer is less than or equal to 1 ppm.

[0044] Furthermore, the molar ratio of the terminator to the anionic polymerization initiator is 1.2-1.5:1.

[0045] Furthermore, the molar ratio of the terminator to the anionic polymerization initiator is 1.3-1.5:1.

[0046] According to the present invention, in step (1), the first mixed solution contains a first organic metal compound.

[0047] In the present invention, when the first mixed solution contains the first organometallic compound, impurities such as water in the first mixed solution can be removed.

[0048] According to the present invention, in step (2), the styrene monomer contains a second organic metal compound.

[0049] In the present invention, when the second organic metal compound is included in the styrene monomer, impurities such as water in the styrene monomer can be removed.

[0050] According to the present invention, the first organometallic compound and the second organometallic compound are each independently selected from at least one of an organoaluminum compound, an organomagnesium compound and an organozinc compound.

[0051] In the present invention, when the above-mentioned organic metal compound is contained, it can not only remove the water in the first mixed liquid and the styrene monomer, but also has no influence on the subsequent second polymerization reaction.

[0052] Further, the first organometallic compound and the second organometallic compound are each independently selected from at least one of a C1-C20 alkylaluminum compound, a C1-C20 alkylmagnesium compound, a C1-C20 alkylzinc compound, a C6-C20 arylaluminum compound, a C6-C20 arylmagnesium compound and a C6-C20 arylzinc compound.

[0053] Furthermore, the first organometallic compound and the second organometallic compound are each independently selected from at least one of di-n-butylmagnesium, di-tert-butylmagnesium, di-sec-butylmagnesium, n-butyl-sec-butylmagnesium, triethylaluminum, triisobutylaluminum, trihexylaluminum, diethylzinc and di-n-butylzinc.

[0054] According to the present invention, in step (1), the anionic polymerization initiator is alkyl lithium.

[0055] Furthermore, the anionic polymerization initiator is n-butyl lithium and / or sec-butyl lithium.

[0056] According to the present invention, the molar ratio of the 1,1-diphenylethylene to the anionic polymerization initiator is 1-1.05:1.

[0057] In the present invention, when the amounts of 1,1-diphenylethylene and anionic polymerization initiator satisfy the above relationship, the initiation reaction rate can be effectively reduced, the difference in molecular weight distribution caused by the time difference of monomer addition during initiation can be prevented, and the molecular weight distribution of the styrene-based polymer can be more concentrated.

[0058] Furthermore, the molar ratio of the 1,1-diphenylethylene to the anionic polymerization initiator is 1-1.02:1.

[0059] Furthermore, the molar ratio of 1,1-diphenylethylene to anionic polymerization initiator is 1:1, thereby ensuring that each styrene-based polymer has a 1,1-diphenylethylene structural unit on its molecular chain, which is conducive to obtaining a styrene-based polymer with a narrow molecular weight distribution.

[0060] According to the present invention, the amount of the first organic metal compound is 2-40 mg relative to 100 g of the first mixed solution.

[0061] In the present invention, when the amount of the first organometallic compound meets the above range, a better impurity removal effect can be obtained, so that the obtained styrene-based polymer has the characteristics of low number average molecular weight and narrow molecular weight distribution.

[0062] Furthermore, relative to 100 g of the first mixed solution, the amount of the first organometallic compound is 5-30 mg.

[0063] According to the present invention, the organic solvent is selected from at least one of cyclohexane, hexane, n-heptane and isooctane.

[0064] In the present invention, when the above organic solvent is used, it is beneficial to regulate the polymerization rate and the solubility of the polymer, thereby controlling the number average molecular weight and molecular weight distribution of the styrene-based polymer.

[0065] Furthermore, the organic solvent is a mixed organic solvent of cyclohexane and hexane.

[0066] Furthermore, the weight ratio of cyclohexane to hexane is 1:0.1-0.3.

[0067] According to the present invention, in step (1), the temperature of the first polymerization reaction is 0-50° C., and the time of the first polymerization reaction is 5-15 min.

[0068] In the present invention, when the above-mentioned first polymerization reaction condition is met, the molecular weight distribution of the obtained styrene-based polymer is narrower.

[0069] Furthermore, the temperature of the first polymerization reaction is 10-40° C., and the time of the first polymerization reaction is 5-10 min.

[0070] According to the present invention, in step (2), the amount of the anionic polymerization initiator is 9-50 mmol relative to 100 g of the styrene monomer.

[0071] Furthermore, relative to 100 g of the styrene monomer, the amount of the anionic polymerization initiator is 12-34 mmol.

[0072] Furthermore, relative to 100 g of the styrene monomer, the amount of the anionic polymerization initiator is 14-27 mmol.

[0073] According to the present invention, the amount of the second organic metal compound is 5-30 mg relative to 100 g of the styrene monomer.

[0074] In the present invention, when the amount of the second organometallic compound meets the above range, a better impurity removal effect can be obtained, so that the prepared styrene-based polymer has the characteristics of low number average molecular weight and narrow molecular weight distribution.

[0075] Furthermore, relative to 100 g of the styrene monomer, the amount of the second organic metal compound is 10-25 mg.

[0076] According to the present invention, the amount of the styrene monomer is 10-30 g relative to 100 g of the organic solvent used in step (1).

[0077] In the present invention, when the amount of styrene monomer meets the above range, it is beneficial to control the polymerization reaction rate.

[0078] Furthermore, relative to 100 g of the organic solvent used in step (1), the amount of the styrene monomer used is 15-25 g.

[0079] According to the present invention, in step (2), the temperature of the low temperature condition is less than or equal to 0°C.

[0080] In the present invention, unless otherwise specified, the temperature of the low temperature condition is the temperature of the solution containing the prepolymer in step (2). When the low temperature condition meets the above range, it can play a role in reducing the rate of the second polymerization reaction when the styrene monomer is added, thereby narrowing the molecular weight distribution of the styrene-based polymer.

[0081] Furthermore, the temperature of the low temperature condition is -40 to 0°C.

[0082] Furthermore, the temperature of the low temperature condition is -20 to 0°C.

[0083] According to the present invention, in step (2), the second polymerization reaction comprises: reacting at the low temperature for 2-10 minutes, heating the polymerization system, and performing the second polymerization reaction; preferably reacting at the low temperature for 5-10 minutes.

[0084] In the present invention, the reaction is first carried out under low temperature conditions, which can play a role in reducing the rate of the second polymerization reaction and avoid the molecular weight distribution of the styrene-based polymer becoming broad due to the failure to mix the raw materials uniformly in time after the styrene monomer is added.

[0085] According to the present invention, the temperature of the second polymerization reaction is 40-120° C., and the time of the second polymerization reaction is 40-100 min.

[0086] In the present invention, when the conditions of the second polymerization reaction meet the above range, the reaction rate of the second polymerization can be increased and the production efficiency can be improved.

[0087] Furthermore, the temperature of the second polymerization reaction is 70-110° C., and the time of the second polymerization reaction is 50-80 min.

[0088] In the present invention, there is no particular limitation on the selection of the terminator, and a conventional compound containing active hydrogen in the art can be selected as the terminator to make the active chain of the styrene-based polymer lose its reactive activity. Preferably, the terminator is selected from at least one of deionized water, alcohol and acid.

[0089] Furthermore, the terminator is selected from alcohol and / or organic acid.

[0090] In the present invention, the styrene-based polymer solution needs to be freed from impurities such as solvent and initiator to obtain pure and transparent styrene-based polymer. The present invention has no particular limitation on the method for removing impurities such as solvent and initiator, and the conventional liquid polymer removal method in the art can be used.

[0091] The third aspect of the present invention provides a styrene-based polymer obtained by the above preparation method.

[0092] A fourth aspect of the present invention provides a brominated styrene-based polymer, wherein the brominated styrene-based polymer is obtained by brominating the above-mentioned styrene-based polymer.

[0093] In the present invention, the brominated styrene-based polymer obtained by bromination has excellent thermal stability, fluidity and color stability.

[0094] In the present invention, the method for brominating the styrene-based polymer is not particularly limited, and can be a conventional styrene-based polymer bromination method in the art. A preferred method for brominating the styrene-based polymer comprises: (1) subjecting a mixed solution containing antimony trichloride, a styrene-based polymer, 1,2-dichloroethane, and bromine chloride to a primary reaction, wherein the mass ratio of antimony trichloride to styrene-based polymer is 1:10-15, the mass ratio of styrene-based polymer to 1,2-dichloroethane is 1:8-10, the mass ratio of bromine chloride to 1,2-dichloroethane is 1:4-6, the reaction temperature is 10-30°C, and the residence time is 2-4h. (2) After the primary reaction is completed, a primary reaction product is obtained, and a mixed solution containing aluminum trichloride, bromine chloride and 1,2-dichloroethane is added to the primary reaction product to carry out a secondary reaction; wherein the mass ratio of aluminum trichloride to styrene-based polymer is 1:170-230, the molar ratio of bromine chloride to styrene-based polymer is 0.3-0.5:1, the reaction temperature is controlled to be 20-40°C, and the residence time is 1-2h. (3) The brominated styrene-based polymer solution obtained by the secondary reaction is subjected to gas-liquid separation, and the brominated styrene-based polymer is obtained through neutralization, water washing, evaporation crystallization, suction filtration, and drying.

[0095] According to the present invention, the number average molecular weight of the brominated styrene-based polymer is 7500-30000 g / mol.

[0096] Furthermore, the number average molecular weight of the brominated styrene-based polymer is 9000-21000 g / mol.

[0097] According to the present invention, the 1 wt% thermal weight loss temperature of the brominated styrene-based polymer is greater than or equal to 350°C.

[0098] Furthermore, the 1 wt% thermal weight loss temperature of the brominated styrene-based polymer is greater than or equal to 360°C.

[0099] According to the present invention, the bromine content is 63-75 wt % based on the total mass of the brominated styrene-based polymer.

[0100] Further, the bromine content is 66-70 wt % based on the total mass of the brominated styrene-based polymer.

[0101] According to the present invention, the yellowness index of the brominated styrene-based polymer is ≤0.

[0102] Furthermore, the brominated styrene-based polymer has a yellowness index of ≤-2.

[0103] The present invention will be described in detail below through embodiments and application examples.

[0104] The number average molecular weight and molecular weight distribution index of the styrene-based polymer were determined by gel permeation chromatography. The gel permeation chromatography was performed using an HLC-8320 gel permeation chromatograph produced by Tosoh Corporation of Japan. The chromatographic column was TSKgelSuperMultiporeHZ-N, the standard column was TSKgel SuperMultiporeHZ, the solvent was chromatographically pure tetrahydrofuran (THF), and narrow distribution polystyrene was used as the standard sample. The polymer sample was prepared into a tetrahydrofuran solution with a mass concentration of 1 mg / mL, the injection volume was 10.00 μL, the flow rate was 0.35 mL / min, and the test temperature was 40.0°C.

[0105] The content of 1,1-diphenylethylene structural units in the styrene-based polymer is measured by hydrogen nuclear magnetic resonance spectroscopy.

[0106] The water contents in 1,1-diphenylethylene, organic solvents and styrene monomer were measured using a Karl Fischer titrator.

[0107] The content of polymerization inhibitor in styrene monomer was measured by high performance liquid chromatography.

[0108] The bromine content of brominated styrene-based polymers was tested using a Bruker AVANCE400 superconducting nuclear magnetic resonance instrument (1H-NMR), with a sample tube diameter of 5 mm, a solvent of deuterated chloroform CDCl3, a sample concentration of 15% (W / V), a test temperature of room temperature, 16 scans, and calibration with tetramethylsilane chemical shift of 0 ppm.

[0109] The 1 wt% thermal weight loss of the brominated styrene-based polymer was measured using a TA-2980DSC differential scanning calorimeter. The specific procedure was as follows: first, the temperature was raised to 100°C, kept constant for 5 min, and then raised to 600°C at a rate of 10°C / min in a nitrogen atmosphere.

[0110] The yellowness index of the styrene-based polymer and the brominated styrene-based polymer is measured using a colorimeter.

[0111] The number average molecular weight of the brominated styrene-based polymers was determined by gel permeation chromatography.

[0112] The pressures described in this experiment refer to gauge pressure.

[0113] In the following embodiments, comparative examples and application examples:

[0114] Solvent: The weight ratio of cyclohexane / hexane is 1:0.25. Cyclohexane and hexane are purchased from Sinopharm Reagent Company. They are soaked in 4A molecular sieve for 30 days, and the water content is equal to 5ppm.

[0115] Styrene (St): polymerization grade, purchased from Yanshan Petrochemical, water content equal to 5ppm, inhibitor content equal to 5ppm;

[0116] Initiator: Butyl lithium (Li): provided by J&K Reagent Company, 1.6 mol·L -1 Hexane solution;

[0117] 1,1-Diphenylethylene (DPE): provided by Inotech Reagent Company, analytical grade, water content equal to 10ppm;

[0118] Organometallic compounds: Butyl magnesium (Mg): provided by Inotech Reagent Company, 1.4 mol / L cyclohexane solution;

[0119] Organometallic compounds: Triisobutylaluminum: (Al): provided by Inotech Reagent Company, 1 mol / L hexane solution;

[0120] Isopropanol: provided by Inotech Reagent Company, analytical grade;

[0121] Antimony trichloride: provided by J&K Reagent Company, purity 99.5%;

[0122] 1,2-Dichloroethane: provided by J&K Reagent Company, purity 99.8%;

[0123] Bromine chloride: provided by Inotech Reagent Company, purity 99.8%;

[0124] Aluminum trichloride: provided by J&K Reagent Company, purity 99.99%.

[0125] Unless otherwise specified, the amounts used in the following examples are based on pure substances.

[0126] Example 1

[0127] This example is used to illustrate the styrene-based polymer and its preparation method of the present invention.

[0128] (1) Under argon protection, a cyclohexane / hexane mixed solvent, 1,1-diphenylethylene, and an organic metal compound are added to a 5L reactor, the temperature in the reactor is controlled to be a first polymerization reaction temperature, a designed amount of n-butyl lithium is added to the reactor to obtain a first mixed solution, and a first polymerization reaction is performed to obtain a solution containing a prepolymer (the types of raw materials and specific amounts are shown in Table 1, and the amounts listed in Table 1 are all measured based on pure compounds).

[0129] (2) The temperature of the polymerization system is lowered to below 0°C by a refrigeration system. Under the protection of high-purity inert gas, styrene pretreated with an organometallic compound is added and reacted for 10 minutes. The reactor is then heated to 40-120°C to carry out a second polymerization reaction (the temperature and time of the second polymerization reaction are shown in Table 1. The specific amounts of raw materials are shown in Table 1. The amounts listed in Table 1 are all measured based on pure compounds).

[0130] (3) After the styrene monomer is completely converted, isopropanol is added to terminate the reaction (the specific amount is shown in Table 1, and the amounts listed in Table 1 are all measured based on pure compounds), and then the n-butyl lithium is eluted with water. After standing and stratifying, the aqueous phase is separated, and the obtained oil phase is subjected to reduced pressure distillation to obtain a styrene-based polymer PS1, whose molecular weight, molecular weight distribution and yellowness index are listed in Table 2.

[0131] Embodiment 2-6

[0132] This example is used to illustrate the styrene-based polymer and its preparation method of the present invention.

[0133] The method described in Example 1 is different in that the reaction is carried out using the parameters shown in Table 1 to obtain styrene-based polymers PS2-PS6, which are tested for molecular weight, molecular weight distribution and yellowness index. The results are shown in Table 2.

[0134] Example 7

[0135] The method described in Example 1 was used, except that the temperature of the first polymerization reaction was 50° C. to obtain a styrene-based polymer PS7, which was tested for molecular weight and its distribution. The results are shown in Table 2.

[0136] Example 8

[0137] The method described in Example 1 was used, except that the temperature of the solution containing the prepolymer was 50° C. before styrene was added, to obtain a styrene-based polymer PS8. The molecular weight and its distribution were tested. The results are shown in Table 2.

[0138] Example 9

[0139] According to the method described in Example 1, except that the amount of 1,1-diphenylethylene added is 36 g, the amount of butyl lithium used is 200 mmol, and the amount of isopropanol used is 15 g, a styrene-based polymer PS9 is obtained, and the molecular weight and its distribution are tested. The results are shown in Table 2.

[0140] Example 10

[0141] According to the method described in Example 1, except that the amount of 1,1-diphenylethylene added is 7.2 g, the amount of butyl lithium used is 40 mmol, and the amount of isopropanol used is 3.5 g, a styrene-based polymer PS10 is obtained, and the molecular weight and its distribution are tested. The results are shown in Table 2.

[0142] Comparative Example 1

[0143] The method described in Example 1 is different in that DPE (1,1-diphenylethylene) is not added, and anionic solution polymerization of styrene monomer is directly carried out to obtain styrene-based polymer DPS1. The molecular weight and its distribution are tested. The results are shown in Table 2.

[0144] Comparative Example 2

[0145] The method described in Example 1 is different in that the organic solvent and the styrene monomer are not treated with an organic metal compound, wherein the total water content of 1,1-diphenylethylene and the organic solvent is 5 ppm, the water content in the styrene monomer is 5 ppm, and the polymerization inhibitor is 5 ppm. A styrene-based polymer DPS2 is obtained, and the molecular weight and its distribution are tested, and the results are shown in Table 2.

[0146] Comparative Example 3

[0147] The method described in Example 1 is different in that the amount of isopropanol used is 4 g, so that the molar ratio of the terminator to the initiator is 0.83; the styrene-based polymer DPS3 is obtained, and the molecular weight and its distribution are tested. GPC shows a bimodal distribution and the color is yellow. The results are shown in Table 2.

[0148] Table 1

[0149]

[0150]

[0151] Table 1

[0152]

[0153]

[0154] Table 2

[0155]

[0156] It can be seen from Table 2 that the styrene-based polymer prepared in the present invention has low molecular weight, narrow molecular weight distribution and good color, and is particularly suitable as a raw material for brominated styrene-based polymer.

[0157] Application Examples

[0158] The styrene-based polymers PS1 to PS10 prepared in the examples were used to prepare brominated styrene-based polymers, and the structure and performance test data are listed in Table 3. The preparation method is as follows:

[0159] (1) A mixed solution containing antimony trichloride, styrene-based polymer, 1,2-dichloroethane and bromine chloride is subjected to a primary reaction, wherein the mass ratio of antimony trichloride to styrene-based polymer is 1:12.5, the mass ratio of styrene-based polymer to 1,2-dichloroethane is 1:9, the mass ratio of bromine chloride to 1,2-dichloroethane is 1:5, the reaction temperature is 20°C, and the residence time is 3 hours. (2) After the primary reaction is completed, a primary reaction product is obtained, and a mixed solution containing aluminum trichloride, bromine chloride and 1,2-dichloroethane is added to the primary reaction product to carry out a secondary reaction; wherein the mass ratio of aluminum trichloride to styrene-based polymer is 1:200, the molar ratio of bromine chloride to styrene-based polymer is 0.4:1, the reaction temperature is controlled to be 30°C, and the residence time is 1.5 hours. (3) The brominated styrene-based polymer solution obtained by the secondary reaction is subjected to gas-liquid separation, and the brominated styrene-based polymer is obtained through neutralization, water washing, evaporation crystallization, suction filtration, and drying.

[0160] Application comparison

[0161] The brominated styrene-based polymer was prepared according to the method in the application example, except that the brominated styrene-based polymers DPS1 to DPS3 prepared in Comparative Examples 1-3 were used to prepare the brominated styrene-based polymer, and the structure and performance test data are listed in Table 3.

[0162] Table 3

[0163]

[0164]

[0165] It can be seen from Table 3 that the brominated styrene-based polymer prepared using the styrene-based polymer provided by the present invention has a bromine content of more than 65.5%, a 1% thermal weight loss temperature greater than or equal to 350° C., and a yellowness index less than or equal to 0, and is particularly suitable as a flame retardant for high-end engineering plastics.

[0166] The preferred embodiments of the present invention are described in detail above, but the present invention is not limited thereto. Within the technical concept of the present invention, the technical solution of the present invention can be subjected to a variety of simple modifications, including the combination of various technical features in any other suitable manner, and these simple modifications and combinations should also be regarded as the contents disclosed by the present invention and belong to the protection scope of the present invention.

Claims

1. A styrene-based polymer, characterized in that The styrene-based polymer includes a styrene structural unit and a 1,1-diphenylethylene structural unit; The molecular weight distribution index of the styrene-based polymer is 1-1.1; The number average molecular weight of the styrene-based polymer is 2000-11000 g / mol.

2. The styrene-based polymer according to claim 1, wherein The number average molecular weight of the styrene-based polymer is 3000-8000 g / mol, preferably 4000-7000 g / mol; Preferably, the molecular weight distribution index of the styrene-based polymer is 1-1.05, preferably 1-1.03; Preferably, based on the total mass of the styrene-based polymer, the content of the 1,1-diphenylethylene structural unit is 1.6-9wt%, preferably 2.2-6wt%, and more preferably 2.5-4.5wt%.

3. The styrene-based polymer according to claim 1 or 2, wherein The yellowness index of the styrene-based polymer is from -6 to 2, preferably from -6 to 0, and more preferably from -6 to -2.

4. A method for preparing a styrene-based polymer, characterized in that: The preparation method comprises: (1) in the presence of a protective gas, 1,1-diphenylethylene, an anionic polymerization initiator and an organic solvent are mixed to obtain a first mixed solution, and under polymerization reaction conditions, the first mixed solution is subjected to a first polymerization reaction to obtain a solution containing a prepolymer; wherein the total water content of the 1,1-diphenylethylene and the organic solvent is less than or equal to 1 ppm; (2) adding styrene monomer to the solution containing the prepolymer obtained in step (1) under low temperature conditions and in the presence of a protective gas to carry out a second polymerization reaction; wherein the water content in the styrene monomer is less than or equal to 1 ppm; and the content of the polymerization inhibitor in the styrene monomer is less than or equal to 1 ppm; (3) after the second polymerization reaction is completed, a terminator is used to terminate the reaction to obtain a styrene-based polymer solution, and a styrene-based polymer is obtained through post-treatment; The molar ratio of the terminator to the anionic polymerization initiator is 1-2:

1.

5. The method for preparing a styrene-based polymer according to claim 4, wherein: The molar ratio of the terminator to the anionic polymerization initiator is 1.2-1.5:1, preferably 1.3-1.5:1; Preferably, in step (1), the first mixed solution comprises a first organometallic compound; Preferably, in step (2), the styrene monomer comprises a second organometallic compound; Preferably, the first organometallic compound and the second organometallic compound are each independently selected from at least one of an organoaluminum compound, an organomagnesium compound and an organozinc compound; Preferably, the first organometallic compound and the second organometallic compound are each independently selected from at least one of a C1-C20 alkylaluminum compound, a C1-C20 alkylmagnesium compound, a C1-C20 alkylzinc compound, a C6-C20 arylaluminum compound, a C6-C20 arylmagnesium compound and a C6-C20 arylzinc compound; More preferably, the first organometallic compound and the second organometallic compound are each independently selected from at least one of di-n-butylmagnesium, di-tert-butylmagnesium, di-sec-butylmagnesium, n-butyl-sec-butylmagnesium, triethylaluminum, triisobutylaluminum, trihexylaluminum, diethylzinc and di-n-butylzinc.

6. The method for preparing a styrene-based polymer according to claim 4 or 5, wherein: In step (1), the anionic polymerization initiator is an alkyl lithium, preferably n-butyl lithium and / or sec-butyl lithium; Preferably, the molar ratio of the 1,1-diphenylethylene to the anionic polymerization initiator is 1-1.05:1, preferably 1-1.02:1; Preferably, the amount of the first organometallic compound is 2-40 mg, preferably 5-30 mg, relative to 100 g of the first mixed solution; Preferably, the organic solvent is selected from at least one of cyclohexane, hexane, n-heptane and isooctane, preferably a mixed organic solvent of cyclohexane and hexane; Preferably, the weight ratio of cyclohexane to hexane is 1:0.1-0.

3.

7. The method for preparing a styrene-based polymer according to any one of claims 4 to 6, wherein: In step (1), the temperature of the first polymerization reaction is 0-50°C, preferably 10-40°C; the time of the first polymerization reaction is 5-15min, preferably 5-10min.

8. The method for preparing a styrene-based polymer according to any one of claims 4 to 7, wherein: In step (2), the amount of the anionic polymerization initiator is 9-50 mmol, preferably 12-34 mmol, and more preferably 14-27 mmol, relative to 100 g of the styrene monomer; Preferably, relative to 100 g of the styrene monomer, the amount of the second organometallic compound is 5-30 mg, preferably 10-25 mg; Preferably, relative to 100 g of the organic solvent used in step (1), the amount of the styrene monomer used is 10-30 g, preferably 15-25 g.

9. The method for preparing a styrene-based polymer according to any one of claims 4 to 8, wherein: In step (2), the temperature of the low temperature condition is less than or equal to 0°C, preferably -40 to 0°C, more preferably -20 to 0°C; Preferably, in step (2), the second polymerization reaction comprises: reacting for 2-10 minutes under the low temperature conditions, heating the polymerization system, and performing the second polymerization reaction; Preferably, the temperature of the second polymerization reaction is 40-120° C., preferably 70-110° C.; the time of the second polymerization reaction is 40-100 min, preferably 50-80 min.

10. The method for preparing a styrene-based polymer according to any one of claims 4 to 9, wherein: In step (3), the terminator is selected from at least one of deionized water, alcohol and acid; Preferably, the terminator is selected from alcohols and / or organic acids.

11. A styrene-based polymer obtained by the preparation method according to any one of claims 4 to 10.

12. A brominated styrene-based polymer, characterized in that The brominated styrene-based polymer is obtained by brominating the styrene-based polymer according to any one of claims 1 to 3 and 11; Preferably, the number average molecular weight of the brominated styrene-based polymer is 7500-30000 g / mol, preferably 9000-21000 g / mol; Preferably, the 1 wt% thermal weight loss temperature of the brominated styrene-based polymer is greater than or equal to 350° C., preferably greater than or equal to 360° C.; Preferably, the bromine content is 63-75 wt%, preferably 66-70 wt%, based on the total mass of the brominated styrene-based polymer; Preferably, the brominated styrene-based polymer has a yellowness index of ≤ 0, preferably ≤ -2.

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