A branched polycarbonate and a method for preparing the same

Abstract

The application provides a branched flame-retardant polycarbonate and a preparation method thereof. The branched flame-retardant polycarbonate is synthesized by using melamine and tetrachloro-p-terephthalic acid as a branching agent. The preparation method comprises the following steps: reacting a bisphenol compound and the branching agent with an inert organic solvent containing phosgene in a reactor to obtain a polycarbonate oligomer solution, and performing a polycondensation reaction on the polycarbonate oligomer to obtain the polycarbonate. The method can improve the reaction rate without using a catalyst, solves the process risk and operation difficulty caused by the catalyst, makes the conversion rate of the end-capping agent greater than 99.5%, and introduces the halogen-containing branching agent to make the flame-retardant performance reach the 1.0mm V0 level, and meanwhile, the product has better light stability and yellowing resistance.

Description

Technical Field

[0001] This invention relates to a branched flame-retardant and yellowing-resistant polycarbonate and its preparation method, belonging to the field of polymer materials technology. Background Technology

[0002] Polycarbonate (PC), as an important engineering plastic, has attracted much attention due to its excellent physical properties and wide range of applications. However, during extrusion and injection molding processes, polycarbonate is subjected to high temperatures and shear, resulting in yellowing and degradation under light and heat, which reduces its usability. Furthermore, flame retardant properties are also required for polycarbonate products. Overcoming these inherent drawbacks to enhance its usability has become an important research direction.

[0003] As reported in published patents CN103059544A and CN105623231B, polycarbonate is typically blended with additives to achieve different properties. However, during prolonged use, the additives can precipitate from the interior of the polycarbonate to the surface, reducing its effectiveness and causing surface defects in the product. Patent JPH09316187 introduces groups containing UV-resistant functions into the polycarbonate molecular chain through chemical bonds, thereby giving the polycarbonate UV-resistant properties. However, branching agents containing terminal hydroxyl groups are prone to react with acyl chlorides, reducing their effectiveness.

[0004] Patent JP6357408B2 discloses the following method: using polycarbonate oligomers with introduced branching agents, the polycarbonate oligomers are reacted with diphenols to produce branched polycarbonate. The drawback of this method is that the resulting branched polycarbonate film has a large number of crystal points, and the addition of triethylamine as a catalyst during the reaction makes the post-processing relatively complicated.

[0005] In existing methods, various additives usually have only a single function and cannot achieve compatibility of multiple properties. The addition of multiple free additives further exacerbates the migration of additives, resulting in problems such as crystal points on the surface of polycarbonate products and poor stability. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the present invention aims to provide a branched flame-retardant and yellowing-resistant polycarbonate and its preparation method. This invention synthesizes a novel branching agent, which not only increases the flame retardancy of polycarbonate but also results in a branched polycarbonate with improved light stability and yellowing resistance. To achieve this objective, the present invention adopts the following technical solution:

[0007] A branched flame-retardant polycarbonate, which uses a compound with the following structure as a branching agent:

[0008]

[0009] Where x is a natural number from 1 to 4, preferably 4.

[0010] Preferably, the branching agent is prepared by reacting melamine with tetrachloroterephthalic acid.

[0011] Preferably, the reaction is carried out in a solvent, which is a mixture of water and DMSO, wherein the mass ratio of water to DMSO is 3:1 to 6:1;

[0012] Preferably, the reaction temperature is 70-90℃;

[0013] Preferably, the mass ratio of melamine to tetrachloroterephthalic acid is 1:5-1:8;

[0014] Preferably, the mass ratio of water to DMSO is 4:1 to 6:1;

[0015] The present invention also provides a method for preparing the polycarbonate, comprising the following steps:

[0016] (1) First, mix the bisphenol compound and the alkaline solution to obtain mixture A, and mix the branching agent and the solvent to obtain mixture B;

[0017] (2) Add the mixture A and mixture B obtained in step (1) into the reactor respectively to react with phosgene to obtain polycarbonate oligomer solution;

[0018] (3) Polycarbonate is obtained by polycondensation reaction of the polycarbonate oligomer solution obtained in step (2).

[0019] Preferably, an optional alkali solution and a capping agent are added in step (3).

[0020] Preferably, in step (3), the polycarbonate oligomer is dispersed by a disperser to obtain an emulsion before undergoing a polycondensation reaction.

[0021] Preferably, a bisphenol compound is also added to the polycondensation reaction in step (3).

[0022] In step (1), in order to better dissolve the bisphenol compound and the branching agent, appropriate heating can be carried out at a temperature of 30-40℃.

[0023] Mixtures A and B are reacted in a phosgene reactor to obtain polycarbonate oligomers. The molecular chains of these polycarbonate oligomers can ionize in the reaction solution to form polymer chains containing phenolic anions, thus acting as surfactants at the water-oil interface to stabilize the emulsion. Subsequently, an alkali solution and a capping agent are added to the obtained polycarbonate oligomers, and the mixture is then dispersed to obtain an emulsion, which is then transported to a polycondensation reactor. After reacting with bisphenol A, polycarbonate is obtained. The polycondensation reactor can be a single reactor, or two or three reactors. In summary, this invention improves the synthesis rate of polycarbonate without adding a catalyst, eliminates the process risks and operational difficulties associated with catalysts, improves the conversion efficiency of the capping agent, and successfully prepares branched polycarbonate with a capping agent conversion rate >99.5%.

[0024] The bisphenol compound mentioned in step (1) is one or more of 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A), bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, bis(4-hydroxyphenyl)sulfide, 4,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)oxide, and bis(4-hydroxyphenyl)sulfone, preferably bisphenol A;

[0025] The molar ratio of the bisphenol compound and the branching agent in step (1) is 45 to 65:1.

[0026] Preferably, the pH of the mixture A in step (1) is 11 to 14.

[0027] Preferably, the alkaline solution is selected from aqueous solutions of alkali metal hydroxides or alkali metal carbonates, and more preferably aqueous solutions of sodium hydroxide or potassium hydroxide.

[0028] Preferably, the molar amount of phosgene is 1.08-1.25 times the sum of the molar amounts of the branching agent and bisphenol, and more preferably 1.12-1.21 times.

[0029] Preferably, phosgene is dissolved in an inert solvent.

[0030] As a preferred embodiment, the reaction temperature in step (2) is 20-35°C and the residence time is 5-15 min.

[0031] As a preferred embodiment, the amount of bisphenol compound added in step (3) is 0.0001 to 0.11 times the mass of the bisphenol compound in step (1);

[0032] Preferably, the capping agent is a monohydric phenol, which may be one or more of phenol, p-tert-butylphenol, cumylphenol, and isooctylphenol;

[0033] Preferably, the amount of capping agent added is 3.0% to 8.0% of the total molar amount of bisphenol compound and branching agent added in steps (2) and (3);

[0034] Preferably, the disperser is a dynamic disperser, and the rotation speed can reach 3000-20000 rpm.

[0035] As a preferred embodiment, the disperser operates at a temperature of 20–30°C.

[0036] Preferably, the average particle size of the latex particles in the emulsion is 5.0–11.0 μm.

[0037] As a preferred embodiment, the reaction conditions in step (3) are as follows:

[0038] Preferably, the amount of alkali solution added in step (3) is 0.05% to 5% of the total mass of mixture A in step (2).

[0039] Preferably, the reaction equipment is a single reactor, two reactors in series, or three reactors in series;

[0040] Preferably, the reaction residence time is 0.4–4 h and the reaction temperature is 30–35 °C;

[0041] The polycarbonate reaction solution obtained in step (3) is demulsified, separated, purified, and dried to obtain the polycarbonate product.

[0042] As a preferred embodiment, the weight-average molecular weight of the carbonate polymer obtained in step (3) is 18,000-45,000 g / mol;

[0043] As a preferred embodiment, the conversion rate of the capping agent is >99.5%.

[0044] As a preferred embodiment, the prepared polycarbonate achieves a flame retardant performance of 1.0 mm V0, while also exhibiting better light stability and resistance to yellowing.

[0045] Compared with the prior art, the advantages of the present invention are:

[0046] (1) By adding BPA to the polycondensation stage, the polycondensation time was shortened without adding a catalyst, the degree of hydrolysis of acyl chloride during polycondensation was reduced, the end-capping efficiency of the end-capping agent was improved, the conversion rate of the end-capping agent was high, and the process risks and operational difficulties brought about by the catalyst were solved.

[0047] (2) The branching agent prepared contains halogens, which enables the flame retardant performance to reach the 1.0 mmV0 level without the addition of flame retardants.

[0048] (3) By using the branching agent to absorb ultraviolet light, the problem of late-stage additive precipitation can be avoided, which can improve the longer-lasting photostability and yellowing resistance of polycarbonate. Detailed Implementation

[0049] The present invention is illustrated by the following embodiments, but the scope of the present invention is not limited to these embodiments.

[0050] The main raw materials used in the embodiments or comparative examples of this invention are:

[0051] BPA: Bisphenol A, industrial grade, purchased from Lihua Yiweiyuan Chemical Co., Ltd.

[0052] THE: 1,1,1-tris(4-hydroxyphenyl)ethane, industrial grade, purchased from Honshu Chemical Industry Co., Ltd.

[0053] PTBP: p-tert-butylphenol, industrial grade, purchased from Tongcheng Chemical Co., Ltd.

[0054] Melamine: analytical grade, purchased from Sigma-Adrich;

[0055] Tetrachloroterephthalic acid: 97%, purchased from Maclean's;

[0056] DMSO: analytical grade, purchased from Sigma-Adrich;

[0057] Sodium hydroxide: analytical grade, purchased from Tianjin Kemeo Chemical Reagent Co., Ltd.;

[0058] Phosgene: Industrial grade, Wanhua Chemical;

[0059] Dichloromethane: analytical grade, purchased from Tianjin Kemeo Chemical Reagent Co., Ltd.;

[0060] Unless otherwise specified, all other raw materials and reagents were purchased from commercially available sources.

[0061] The performance evaluation method is as follows:

[0062] (1) The weight-average molecular weight was determined by gel permeation chromatography. The equipment manufacturer was Agilent Technologies and the equipment model was 1260InfinityⅡ.

[0063] (2) The content of the capping agent in the aqueous phase was determined by high performance liquid chromatography. Equipment manufacturer: Agilent Technologies, equipment model: 1260 Infinity II.

[0064] (3) Indicators for judging the degree of product branching: The indicator for judging the degree of product branching is the melt flow index (MFI) R value. The melt flow index tester manufacturer is Goettfert, and the equipment model is MI40. The specific method is as follows: Test the melt flow index a of the final product under the condition of 300℃ / 1.2kg and the melt flow index b under the condition of 300℃ / 10kg respectively. Then the melt flow index R value = (log(a)-log(b)) / (log(10)-log(1.2))(Ⅰ)

[0065] The melt index R value of linear PC is less than 1.10, and the higher the branching degree, the higher the melt index R value.

[0066] (4) Flame retardant performance: Flame retardancy testing was conducted according to the "Flammability Testing of Plastic Materials, UL94" procedure. The flame retardant rating was determined based on the burning rate, extinguishing time, resistance to drop, and whether the drop was positively burning. The sample used for testing was 125mm in length and 13mm in width. In this invention, the thickness was selected as 1.0mm during testing. According to the UL94 procedure, the flame retardant rating of the material can be classified as (UL94-HB): V0, V1, V2, 5VA and / or 5VB.

[0067] (5) Light stability performance: Tested according to SAE J1960, under the following conditions: irradiance 0.55 W / (m²). 2 *nm)@340nm, blackboard temperature is (70±2)℃, chamber temperature is (50±2)℃, relative humidity is (50±10)%RH, cumulative duration is 168.

[0068] (6) Yellowing resistance: The sample was directly injection molded into a sheet at an injection molding machine barrel temperature of 300℃, and then allowed to remain in the barrel for 20 minutes before injection molding. The change in yellowness index (YI) of the injection-molded sheet before and after the two tests was recorded. The YI test was conducted in accordance with ASTM E313 standard.

[0069] (7) Elemental content analysis: X-ray photoelectron spectroscopy (XPS) was performed using an ESCALAB 250 XPS with AlKαX as the emission source. The binding energy of the tested elements was calibrated using C1s as 284.8 eV.

[0070] (8) Infrared analysis: An INVENIO S-type Fourier transform infrared spectrometer was used in ATR mode, with a wavenumber range of 4000 cm⁻¹. -1 ~400cm -1 The resolution is 4cm. -1 .

[0071] Example 1

[0072] Preparation of branching agents:

[0073] The branching agent is obtained by adding melamine and tetrachloroterephthalic acid in a mass ratio of 1:7.2 to a solvent of water and DMSO in a mass ratio of 4:1, reacting at 80°C, and then drying the reaction solution by rotary evaporation at 90°C.

[0074] Elemental analysis results: Theoretical values: C: 31.6%, O: 18.7%, N: 8.2%, Cl: 41.5%; Actual values: C: 31.4%, O: 19.2%, N: 7.6%, Cl: 41.8%.

[0075] In the infrared spectrum, the branching agent is at 1647 cm⁻¹. -1 and 1541cm -1 A C=O stretching vibration peak appeared at 1531 cm⁻¹. -1 The enhanced stretching vibration peaks of CN and NH confirm the synthesis of the branching agent.

[0076] Preparation of polycarbonate:

[0077] Step (1): Prepare an alkaline solution of BPA (mixture A) and a dichloromethane solution of the branching agent (mixture B) in the mixing tank. The concentration of BPA in mixture A is 15.1 wt% and the concentration of sodium hydroxide is 6.1 wt%. The concentration of the branching agent in mixture B is 7.0 wt%. Purge with nitrogen and start stirring. Keep the obtained alkaline BPA solution at 35°C. Simultaneously prepare an 11 wt% PTBP / dichloromethane solution and place it in the end-capping agent tank.

[0078] Step (2): The alkaline solution of BPA and the dichloromethane solution of the branching agent are injected into the reactor at flow rates of 142.0 g / min and 25.4 g / min, respectively. Phosgene at 11.4 g / min and dichloromethane at 148 g / min are added simultaneously. The reactor outlet temperature is controlled at 32-35℃ and the residence time is 12 min to carry out the phosgenation reaction and obtain a polycarbonate oligomer mixture.

[0079] Step (3): PTBP dichloromethane solution and 32wt% sodium hydroxide aqueous solution were added to the polycarbonate oligomer obtained in step (2) at rates of 6.69 g / min and 4.50 g / min, respectively. The mixture was then fed to a disperser at a speed of 8000 rpm to obtain an emulsion. Mixture A was added to the emulsion at a flow rate of 1.41 g / min. The mixture was reacted in the first polycondensation reactor for 40 min, and then transferred to the second polycondensation reactor. After the reaction in the second polycondensation reactor was completed, polycarbonate was obtained after demulsification, separation, purification, and drying. The test data are shown in Table 1 below.

[0080] Example 2

[0081] Preparation of branching agents:

[0082] Same as Example 1.

[0083] Preparation of polycarbonate:

[0084] Step (1) is the same as in Example 1.

[0085] Step (2): The alkaline solution of BPA and the dichloromethane solution of the branching agent are injected into the reactor at flow rates of 142.0 g / min and 26.3 g / min, respectively. Phosgene at 11.8 g / min and dichloromethane at 115 g / min are added simultaneously. The reactor outlet temperature is controlled at 32-35℃ and the residence time is 12 min to carry out the phosgenation reaction and obtain a polycarbonate oligomer mixture.

[0086] Step (3): PTBP dichloromethane solution and 32wt% sodium hydroxide aqueous solution were added to the polycarbonate oligomer obtained in step (2) at rates of 6.69 g / min and 4.32 g / min, respectively. The mixture was then fed to a disperser at a speed of 12000 rpm to obtain an emulsion. Mixture A was added to the emulsion at a flow rate of 1.15 g / min. The mixture was reacted in the first polycondensation reactor for 40 min, and then transferred to the second polycondensation reactor. After the reaction in the second polycondensation reactor was completed, polycarbonate was obtained after demulsification, separation, purification, and drying. The test data are shown in Table 1 below.

[0087] Example 3

[0088] Preparation of branching agents:

[0089] Same as Example 1.

[0090] Preparation of polycarbonate:

[0091] Step (1) is the same as in Example 1.

[0092] Step (2): The alkaline solution of BPA and the dichloromethane solution of the branching agent are injected into the reactor at flow rates of 142.0 g / min and 25.4 g / min, respectively. Phosgene at a flow rate of 11.0 g / min and dichloromethane at a flow rate of 117 g / min are added simultaneously. The reactor outlet temperature is controlled at 32-35℃ and the residence time is 12 min to carry out the phosgenation reaction and obtain a polycarbonate oligomer mixture.

[0093] Step (3): PTBP dichloromethane solution and 32wt% sodium hydroxide aqueous solution were added to the polycarbonate oligomer obtained in step (2) at rates of 6.18 g / min and 4.41 g / min, respectively. The mixture was then fed to a disperser at a speed of 9000 rpm to obtain an emulsion. Mixture A was added to the emulsion at a flow rate of 1.62 g / min. The mixture was reacted in the first polycondensation reactor for 40 min, and then transferred to the second polycondensation reactor. After the reaction in the second polycondensation reactor was completed, polycarbonate was obtained after demulsification, separation, purification, and drying. The test data are shown in Table 1 below.

[0094] Example 4

[0095] Preparation of branching agents:

[0096] Same as Example 1.

[0097] Preparation of polycarbonate:

[0098] Step (1) is the same as in Example 1.

[0099] Step (2): The alkaline solution of BPA and the dichloromethane solution of the branching agent are injected into the reactor at flow rates of 142.0 g / min and 24.1 g / min, respectively. Phosgene at 11.3 g / min and dichloromethane at 135 g / min are added simultaneously. The reactor outlet temperature is controlled at 32-35℃ and the residence time is 12 min to carry out the phosgenation reaction and obtain a polycarbonate oligomer mixture.

[0100] Step (3): PTBP dichloromethane solution and 32wt% sodium hydroxide aqueous solution were added to the polycarbonate oligomer obtained in step (2) at rates of 6.30 g / min and 4.45 g / min, respectively. The mixture was then fed to a disperser at a speed of 10,000 rpm to obtain an emulsion. Mixture A was added to the emulsion at a flow rate of 1.32 g / min. The mixture was reacted in the first polycondensation reactor for 40 min, and then transferred to the second polycondensation reactor. After the reaction in the second polycondensation reactor was completed, polycarbonate was obtained after demulsification, separation, purification, and drying. The test data are shown in Table 1 below.

[0101] Comparative Example 1

[0102] Step (1): Prepare an alkaline solution of BPA (mixture A) and a dichloromethane solution of THPE (mixture B) in the mixing tank. The concentration of BPA in mixture A is 15.1 wt% and the concentration of sodium hydroxide is 6.1 wt%. The concentration of THPE in mixture B is 7.0 wt%. Purge with nitrogen and start stirring. Place an 11 wt% PTBP / dichloromethane solution in the end-capping agent tank.

[0103] Step (2): The BPA sodium hydroxide mixed solution and the branching agent dichloromethane solution were injected into the reactor at flow rates of 142.0 g / min and 21.4 g / min, respectively. Phosgene at 11.3 g / min and dichloromethane at 135 g / min were added simultaneously. The reactor outlet temperature was controlled at 32-35℃ and the residence time was 12 min to carry out the phosgenation reaction and obtain polycarbonate oligomer mixture.

[0104] Step (3): PTBP dichloromethane solution and 32wt% sodium hydroxide aqueous solution were added at 6.18 g / min and 4.42 g / min to the polycarbonate oligomer mixture obtained in step (2). The mixture was then fed to a disperser at 10000 rpm to obtain an emulsion. This emulsion was reacted in the first polycondensation reactor for 40 min, and then transferred to the second polycondensation reactor. After the reaction in the second reactor was completed, polycarbonate was obtained through demulsification, separation, purification, and drying. Test data are shown in Table 1 below.

[0105] Comparative Example 2

[0106] Step (1): Mix solution A and solution B in the mixing tank and the branching agent tank respectively. The concentration of BPA in solution A is 15.1 wt% and the concentration of sodium hydroxide is 6.1 wt%. The concentration of THPE in solution B is 7.0 wt% and the concentration of alkali solution is 5.6 wt%. Purge with nitrogen and start stirring. Place 11 wt% PTBP / dichloromethane solution in the end-capping agent tank.

[0107] Step (2): The alkaline solutions of BPA and THPE are injected into the reactor at flow rates of 142.0 g / min and 6.7 g / min, respectively. Phosgene at 11.4 g / min and dichloromethane at 148 g / min are added simultaneously. The reactor outlet temperature is controlled at 32-35℃ and the residence time is 12 min. The alkaline solution is continuously added to make the pH of the aqueous phase of the reaction solution 12-13, and the phosgenation reaction is carried out to obtain a polycarbonate oligomer mixture.

[0108] Step (2): The alkaline solutions of BPA and THPE are injected into reactor 3 at flow rates of 142.0 g / min and 8.22 g / min, respectively. Phosgene at 11.4 g / min and dichloromethane at 148 g / min are added simultaneously. The reactor outlet temperature is controlled at 32-35℃ and the residence time is 12 min to carry out the phosgenation reaction and obtain a polycarbonate oligomer mixture.

[0109] Step (3): PTBP dichloromethane solution and 32wt% sodium hydroxide aqueous solution were added to the polycarbonate oligomer mixture obtained in step (2) at rates of 2.34 g / min and 4.51 g / min, respectively. The mixture was then fed to a disperser at a speed of 8000 rpm to obtain an emulsion. This emulsion was reacted in the first polycondensation reactor for 40 min, and then transferred to the second polycondensation reactor. After the reaction in the second reactor was completed, polycarbonate was obtained through demulsification, separation, purification, and drying. Test data are shown in Table 1 below.

[0110] Table 1. Experimental Test Data

[0111]

[0112] The data comparison above shows that this invention, by using a branching agent containing triazine, increases the synthesis rate of polycarbonate without adding a catalyst, eliminates the process risks and operational difficulties brought by catalysts, improves the conversion efficiency of the end-capping agent, and successfully prepares branched polycarbonate with an end-capping agent conversion rate >99.5%, achieving a flame retardant performance at the 1mm V0 level, while also improving the light stability and yellowing resistance of polycarbonate. The above description is merely a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and additions without departing from the method of the present invention, and these improvements and additions should also be considered within the scope of protection of the present invention.

Claims

1. A method for preparing polycarbonate, characterized in that, Includes the following steps: (1) First, mix the bisphenol compound and the alkaline solution to obtain mixture A, and mix the branching agent and the solvent to obtain mixture B; (2) Add the mixture A and mixture B obtained in step (1) into the reactor respectively to react with phosgene to obtain polycarbonate oligomer solution; (3) Polycarbonate oligomer solution obtained in step (2) is subjected to polycondensation reaction to obtain polycarbonate; The branching agent is prepared by reacting melamine with tetrachloroterephthalic acid. In step (3), a capping agent and an optional alkali solution are added, and a bisphenol compound is also added in the polycondensation reaction of step (3).

2. The preparation method according to claim 1, characterized in that, The reaction between melamine and tetrachloroterephthalic acid is carried out in a solvent, which is a mixture of water and DMSO, wherein the mass ratio of water to DMSO is 3:1 to 6:

1.

3. The preparation method according to claim 2, characterized in that, The solvent is a mixture of water and DMSO, wherein the mass ratio of water to DMSO is 4:1 to 6:

1.

4. The preparation method according to claim 1, characterized in that, The reaction temperature of melamine with tetrachloroterephthalic acid is 70-90℃.

5. The preparation method according to claim 1, characterized in that, The mass ratio of melamine to tetrachloroterephthalic acid is 1:5-1:

8.

6. The preparation method according to claim 1, characterized in that, In step (3), the polycarbonate oligomer is dispersed by a disperser to obtain an emulsion and then subjected to a polycondensation reaction.

7. The preparation method according to claim 1, characterized in that, The bisphenol compound mentioned in step (1) is one or more of the following: 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, bis(4-hydroxyphenyl)sulfide, 4,4'-dihydroxybiphenyl, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl)diphenylmethane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)oxide, and bis(4-hydroxyphenyl)sulfone.

8. The preparation method according to claim 7, characterized in that, The bisphenol compound mentioned in step (1) is 2,2-bis(4-hydroxyphenyl)propane.

9. The preparation method according to claim 1, characterized in that, The molar ratio of the bisphenol compound and the branching agent in step (1) is 45~65:

1.

10. The preparation method according to claim 1, characterized in that, The pH of the mixture A in step (1) is 11~14.

11. The preparation method according to claim 1, characterized in that, The alkaline solution is selected from aqueous solutions of alkali metal hydroxides or alkali metal carbonates.

12. The preparation method according to claim 11, characterized in that, The alkaline solution is selected from aqueous solutions of sodium hydroxide or potassium hydroxide.

13. The preparation method according to claim 1, characterized in that, The molar amount of phosgene is 1.08-1.25 times the sum of the molar amounts of the branching agent and the bisphenol compound.

14. The preparation method according to claim 13, characterized in that, The molar amount of phosgene is 1.12 to 1.21 times the sum of the molar amounts of the branching agent and the bisphenol compound.

15. The preparation method according to claim 1, characterized in that, Phosgene dissolves in inert solvents.

16. The preparation method according to claim 1, characterized in that, The reaction temperature in step (2) is 20~35℃ and the residence time is 5-15min.

17. The preparation method according to claim 1, characterized in that, The amount of bisphenol compound added in step (3) is 0.0001 to 0.11 times the mass of bisphenol compound in step (1).

18. The preparation method according to claim 1, characterized in that, The capping agent is a monohydric phenol.

19. The preparation method according to claim 18, characterized in that, The capping agent is one or more of phenol, p-tert-butylphenol, cumylphenol, and isooctylphenol.

20. The preparation method according to claim 1, characterized in that, The amount of capping agent used is 3.0% to 8.0% of the total molar amount of bisphenol compound and branching agent added in steps (2) and (3).

21. The preparation method according to claim 1, characterized in that, The amount of alkali solution added in step (3) is 0.05% to 5% of the total mass of mixture A in step (2).

22. The preparation method according to claim 1, characterized in that, The disperser is preferably a dynamic disperser, and the rotation speed can reach 3000-20000 rpm.

23. The preparation method according to claim 1, characterized in that, The operating temperature of the disperser is 20~30℃.

24. The preparation method according to claim 1, characterized in that, The average particle size of the latex particles in the emulsion is 5.0~11.0 μm.

25. The preparation method according to claim 1, characterized in that, The reaction equipment can be a single reactor, two reactors in series, or three reactors in series.

26. The preparation method according to claim 1, characterized in that, The reaction residence time is 0.4~4h, and the reaction temperature is 30~35℃.

27. The preparation method according to claim 1, characterized in that, The weight-average molecular weight of the carbonate polymer obtained in step (3) is 18,000-45,000 g / mol.

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