An environmentally friendly method for producing polycarbonate

Abstract

This invention belongs to the field of polymer materials technology, specifically relating to a method for producing environmentally friendly polycarbonate. The method includes: S1 adding diphenyl carbonate, isosorbide, and bisphenol fluorene to a reaction vessel under a nitrogen atmosphere, followed by mixing to obtain a mixture; S2 adding a titanium-silicon molecular sieve composite catalyst to the mixture and performing a transesterification reaction, followed by a polycondensation reaction; after the reaction, the product is poured off while hot and cooled to obtain an intermediate product; S3 mixing and stirring the intermediate product, pyridine-type ionic liquid-modified hydrotalcite, rubber elastomer, compatibilizer, and antioxidant to obtain a premix; S4 melt-extruding the premix in a twin-screw extruder, followed by stretching, water cooling, air drying, pelletizing, and final drying to obtain environmentally friendly polycarbonate. The polycarbonate produced by this method not only has low color but also excellent impact resistance, heat resistance, and flame retardancy.

Description

Technical Field

[0001] This invention belongs to the field of polymer materials technology, specifically relating to a method for producing environmentally friendly polycarbonate. Background Technology

[0002] Polycarbonate (PC) is a high molecular polymer containing carbonate groups in its molecular chain, possessing excellent comprehensive properties. Applications of polycarbonate include: (1) Building materials: used to produce fire doors, windows, partitions, and other building components to improve building safety; (2) Electronic equipment: used to manufacture fireproof components for electronic products such as computer casings and mobile phone cases to protect internal components from fire damage; (3) Transportation: used for automotive interior parts, ship components, etc., to improve the overall safety performance of transportation vehicles; (4) Safety equipment: used to manufacture safety equipment such as protective glasses and face masks to provide flame and heat protection.

[0003] Polycarbonate itself has good heat resistance, but under extreme high temperatures exceeding its heat resistance range, it may still decompose and release harmful gases. As the requirements for polymer materials increase, higher demands are being placed on the heat resistance of polycarbonate. Polycarbonate itself possesses a certain degree of flame retardancy, achieving a flame retardancy rating of V-2, making it a self-extinguishing engineering plastic. This means that under specific conditions, polycarbonate materials can self-extinguish during combustion, thereby slowing the spread of fire. To meet higher flame retardancy standards, such as achieving a V-0 flame retardancy rating, flame retardants are typically added to further enhance the flame retardant properties of polycarbonate. These flame retardants mainly include phosphate esters, organosilicon compounds, and sulfonates. While these flame retardants can improve the flame retardancy of polycarbonate products to some extent, they are not very environmentally friendly during use. Furthermore, current research often blends PC with other polymers with good toughness (such as polyamide, i.e., nylon) to increase the toughness of polycarbonate products. However, the addition of these polymers results in high toughness but low strength, and does not significantly improve the impact resistance of polycarbonate materials. Catalysts play a crucial role in the preparation of polycarbonate. Currently, the main catalysts include organotin compounds, zinc salts, and titanium salts. These metal compound catalysts are not removed during polycarbonate preparation; some metal ions are also released into the polycarbonate, which is not only environmentally friendly but also contributes to the high color of the polycarbonate.

[0004] Therefore, there is an urgent need for an environmentally friendly method for producing polycarbonate, which produces polycarbonate with characteristics such as heat resistance, impact resistance, flame retardancy (94V0), and good mechanical properties within the general operating temperature range. Summary of the Invention

[0005] The purpose of this invention is to provide an environmentally friendly method for producing polycarbonate. The raw materials used in this method are all environmentally friendly, and the polycarbonate produced by this method not only has low color but also excellent impact resistance, heat resistance, and flame retardancy.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] This invention provides a method for producing environmentally friendly polycarbonate, the method comprising:

[0008] S1 involves adding diphenyl carbonate, isosorbide, and bisphenol fluorene into a reaction vessel, protecting the mixture under a nitrogen atmosphere, and then mixing them to obtain a mixture.

[0009] S2 adds a titanium-silicon molecular sieve composite catalyst to the mixture and then carries out an ester exchange reaction, followed by a polycondensation reaction. After the reaction is completed, the product is poured out while hot and then cooled to obtain an intermediate product.

[0010] S3 mixes and stirs the intermediate product, pyridine-type ionic liquid modified hydrotalcite, rubber elastomer, compatibilizer and antioxidant to obtain a premix;

[0011] S4 processes the premix in a twin-screw extruder through melt extrusion, stringing, water cooling, air drying, pelletizing, and drying to obtain environmentally friendly polycarbonate.

[0012] Further, the molar ratio of diphenyl carbonate, isosorbide and bisphenol fluorene is 1:(0.5-0.7):(0.3-0.4), preferably 1:0.6:0.4.

[0013] Further, in step S1, the mixing conditions include: first melting the reactants at 120-160°C, and then stirring at 500-600 rpm for 5-20 minutes at 120-160°C.

[0014] Furthermore, the weight of the titanium-silicon molecular sieve composite catalyst is 0.01-0.04% of the weight of diphenyl carbonate.

[0015] Furthermore, the conditions for the transesterification include: a temperature of 180-190°C, a pressure of 35-45 kPa, and a time of 1-2 hours.

[0016] Furthermore, the conditions for the polycondensation reaction include: heating to 280-300℃, starting the vacuum pump to evacuate the reactor to a pressure of 70-80 Pa, and reacting for 1-2 hours.

[0017] The catalysts used in the prior art are generally metal catalysts. However, metal catalysts have the drawback of metal leaching, which harms the ecological environment. Moreover, after the reaction, metal ions are generally present in the polymer, which can cause defects such as poor polymer color. The alkaline molecular sieve composite catalyst in this invention refers to a catalyst with alkaline molecular sieve as the main body. The titanium-silicon molecular sieve composite catalyst of this invention has excellent stability, and its metal does not fall off, which has excellent environmental protection properties. At the same time, it can also avoid other performance defects caused by metal ion leaching.

[0018] Furthermore, the preparation method of the titanium-silicon molecular sieve composite catalyst includes:

[0019] (1) Disperse titanium silicon molecular sieve in ethanol to obtain a suspension, then add 3-mercaptopropyltrimethoxysilane to react, and after the reaction is completed, cool the system to room temperature to obtain a material containing mercapto-modified titanium silicon molecular sieve.

[0020] (2) 1-Allyl-3-methylimidazolium hexafluorophosphate and azobisisobutyronitrile were added to the material containing mercapto-modified titanium silicon molecular sieve and mixed at room temperature to obtain a mixture. The mixture was then loaded into a high-pressure reactor to initiate the reaction. After the reaction was completed, the system was cooled to room temperature and centrifuged to obtain a solid precipitate. The solid precipitate was washed with water and then dried to obtain a titanium silicon molecular sieve composite catalyst.

[0021] Furthermore, in step (1): the dispersion conditions include: dispersion under ultrasonic conditions for 20-30 minutes.

[0022] Further, in step (1): the reaction conditions include: reacting at 50-60℃ for 0.5-1 hours, followed by reflux reaction at 80-90℃ for 5-7 hours.

[0023] Furthermore, in step (1): the number of times the ethanol is washed is 3-6 times.

[0024] Furthermore, the silicon-to-titanium molar ratio of the titanium-silicon molecular sieve is 30-70.

[0025] Furthermore, the average particle size of the titanium-silicon molecular sieve is 0.2-10 micrometers.

[0026] The titanium-silicon molecular sieve in this invention is commercially available, and was purchased from Auscatalytic Materials (Dalian) Co., Ltd.

[0027] Further, in step (1): the weight ratio of the titanium silicon molecular sieve to ethanol is 1:(100-200).

[0028] Further, in step (1): the weight ratio of the titanium silicate molecular sieve to 3-mercaptopropyltrimethoxysilane is 1:(10-20).

[0029] Furthermore, the weight ratio of the titanium silicate molecular sieve to 1-allyl-3-methylimidazolium hexafluorophosphate is 1:(0.1-1), preferably 1:(0.3-0.4).

[0030] Further, the weight ratio of the titanium silicate molecular sieve to azobisisobutyronitrile is 1:(0.01-0.1), preferably 1:(0.05-0.06).

[0031] Furthermore, in step (2), the conditions for initiating the reaction include reacting at 95-120°C for 15-20 hours.

[0032] Furthermore, in step (2), the drying conditions include: a temperature of 70-80℃, a vacuum degree of 0.07-0.09MPa, and a time of 8-20 hours.

[0033] Furthermore, in step (2): the water washing is performed 3-5 times.

[0034] While polycarbonate resins can be prepared using titanium-silicon molecular sieves alone, the inventors found that the resulting polycarbonate resins had poor heat resistance. However, the titanium-silicon molecular sieve composite catalyst modified with 1-allyl-3-methylimidazolium hexafluorophosphate in this invention can not only synthesize polycarbonate resins, but also produce polycarbonate resins with good heat resistance. This may be because the titanium-silicon molecular sieve composite catalyst in this invention can better control the distribution of polymer molecules during the preparation process, resulting in polycarbonate resins with a narrower molecular weight distribution, thus giving them better heat resistance.

[0035] Existing flame retardants generally use bromine-based, nitrogen-based, and red phosphorus flame retardants, which are not environmentally friendly when used. The inventors of this invention have discovered that using pyridine-type ionic liquid to modify hydrotalcite not only has excellent environmental performance, but also achieves better flame retardant effect compared to traditional flame retardants.

[0036] Furthermore, the preparation method of the pyridine-type ionic liquid modified hydrotalcite includes: dispersing hydrotalcite in anhydrous ethanol, then adding pyridine-type ionic liquid and stirring, then adding silane coupling agent dropwise to react and obtain the hydrotalcite. After the addition is complete, continue the reaction for 30-40 minutes, then filter and dry the solid phase to obtain pyridine-type ionic liquid modified hydrotalcite.

[0037] In this invention, the addition of pyridine-type ionic liquid to modify hydrotalcite not only improves the flame retardancy of polycarbonate but also enhances its impact resistance. This is likely because some of the pyridine-type ionic liquid is linked to hydrotalcite via a coupling agent, and some of the pyridine-type ionic liquid may also be linked to the interlayer hydroxyl groups of hydrotalcite via hydrogen bonds. During flame retardation, hydrotalcite can release structural water and interlayer anions. These released substances can effectively reduce combustion gases. At this time, the hydrogen bonds and π-π stacking structure in the pyridine-type ionic liquid interact with the specific structure of hydrotalcite, further increasing the stability and heat resistance of the molecules in the system, resulting in superior high-temperature flame retardancy.

[0038] Furthermore, the average particle size of the hydrotalcite is 0.1-2 micrometers, preferably 0.5-1 micrometers.

[0039] The magnesium-aluminum hydrotalcite in this invention is commercially available, for example, magnesium-aluminum hydrotalcite purchased from KSM (Dandong) High-Tech Materials Technology Co., Ltd., with an average particle size of 0.6 micrometers.

[0040] Furthermore, the pyridine-type ionic liquid is selected from N-C2-C10 alkylpyridine bromide, preferably N-C4-C8 alkylpyridine bromide. Examples of N-C4-C8 alkylpyridine bromide include N-butylpyridine bromide, N-hexylpyridine bromide, and N-octylpyridine bromide.

[0041] Further research revealed that pyridine-type ionic liquid-modified hydrotalcite prepared using brominated N-C4-C8 alkylpyridine can better increase the impact resistance of polycarbonate, especially its low-temperature impact resistance. This may be because the pyridine-type ionic liquid-modified hydrotalcite has a lamellar structure, which can better play a toughening role. The pyridine-type ionic liquid can act as a plasticizer, especially at low temperatures. The long-chain structure in brominated N-C4-C8 alkylpyridine can prevent the freezing of molecular chains, giving polycarbonate better low-temperature impact toughness.

[0042] Furthermore, the coupling agent is selected from at least one of KH550, KH550, KH560, KH580, KH590, KH602 and KH792.

[0043] Furthermore, the weight ratio of the hydrotalcite to anhydrous ethanol is 1:(20-40).

[0044] Furthermore, the weight ratio of the hydrotalcite to the pyridine-type ionic liquid is 1:(0.2-1), preferably 1:(0.3-0.4).

[0045] Further, the weight ratio of the hydrotalcite to the silane coupling agent is 1:(0.05-0.1), preferably 1:(0.03-0.04).

[0046] Furthermore, in the preparation of pyridine-type ionic liquid modified hydrotalcite, the silane coupling agent is added dropwise over 30-40 minutes. Those skilled in the art can adjust the dropwise acceleration rate according to the dropwise addition time, which will not be elaborated upon here.

[0047] Furthermore, in the preparation of pyridine-type ionic liquid-modified hydrotalcite, the reaction conditions include: a temperature of 40-45℃.

[0048] Furthermore, in the preparation of pyridine-type ionic liquid modified hydrotalcite, the drying conditions include: a temperature of 50-60℃, a vacuum degree of 0.07-0.09MPa, and a time of 5-10 hours.

[0049] Furthermore, the rubber elastomer is selected from SEBS elastomers.

[0050] When rubber elastomers are used alone to increase the toughness of polycarbonate, there is often a disadvantage of "high toughness and low strength". It is not particularly advantageous to increase the impact strength of the final polycarbonate. In this invention, the synergistic effect of rubber elastomers and pyridine-type ionic liquid modified hydrotalcite can achieve the advantages of high strength and high toughness, thereby better increasing the impact resistance of polycarbonate.

[0051] Furthermore, the melt index of the SEBS elastomer at 230°C and 5.0 kg is 2-8 g / 10 min, preferably 4-6 g / 10 min.

[0052] The SEBS elastomer used in this invention is commercially available, preferably SEBS G1652 from Kraton, USA, which has a melt index of 5 g / 10 min at 230°C and 5.0 kg.

[0053] Furthermore, the compatibilizer is selected from styrene-grafted maleic anhydride and / or polystyrene-grafted glycidyl methacrylate, preferably styrene-grafted maleic anhydride.

[0054] The compatibilizer in this invention can be obtained commercially, for example, styrene-grafted maleic anhydride is Kreville's styrene-grafted maleic anhydride, model SMA1000P.

[0055] Furthermore, the antioxidant is selected from at least one of antioxidant 1010, antioxidant 1076, antioxidant 1098, antioxidant 2246, antioxidant 264, antioxidant 300, antioxidant 442, antioxidant BHT, and antioxidant DSTP.

[0056] Furthermore, the weight ratio of the intermediate product to the pyridine-type ionic liquid modified hydrotalcite is 100:(25-30).

[0057] Furthermore, the weight ratio of the intermediate product to the rubber elastomer is 100:(10-15).

[0058] Furthermore, the weight ratio of the intermediate product to the compatibilizer is 100:(1-3).

[0059] Furthermore, the weight ratio of the intermediate product to the antioxidant is 100:(0.1-0.3).

[0060] Furthermore, in step S3, the mixing conditions include: a stirring speed of 1200-2000 rpm and a time of 5-10 minutes.

[0061] Further, in step S4, the conditions for melt extrusion include: the temperature control of zones one to eight of the twin-screw extruder is as follows: zone one temperature 260-280℃, zone two temperature 270-290℃, zone three temperature 270-290℃, zone four temperature 280-300℃, zone five temperature 280-300℃, zone six temperature 280-300℃, zone seven temperature 280-300℃, and zone eight temperature 280-300℃; and the screw speed is 300-400 rpm.

[0062] Further, in step S4, the conditions for melt extrusion include: the temperature control of zones one to eight of the twin-screw extruder is as follows: zone one temperature 270℃, zone two temperature 275℃, zone three temperature 275℃, zone four temperature 285℃, zone five temperature 290℃, zone six temperature 290℃, zone seven temperature 290℃, and zone eight temperature 290℃; and the screw speed is 300-400 rpm.

[0063] In step S4 of this invention, the processes of stringing, water cooling, air drying, pelletizing, and drying are conventional techniques in the field and will not be elaborated upon in this invention.

[0064] Compared with the prior art, the advantages and beneficial effects of the present invention are as follows:

[0065] The polycarbonate produced by the method of this invention exhibits low color and high impact resistance, especially at low temperatures, while also possessing excellent flame retardancy and heat resistance. This is presumably because the titanium-silicon molecular sieve composite catalyst in this invention enables the preparation of polycarbonate intermediate products with a narrow molecular weight distribution. Simultaneously, the pyridine-type ionic liquid-modified hydrotalcite, the rubber elastomer, and the polycarbonate intermediate products work together to achieve toughening, reinforcement, and heat resistance. Detailed Implementation

[0066] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0067] Example 1

[0068] This embodiment provides a method for producing environmentally friendly polycarbonate, which includes: S1 adding diphenyl carbonate, isosorbide, and bisphenol fluoride into a reactor under nitrogen atmosphere protection, and then mixing to obtain a mixture; S2 adding a titanium-silicon molecular sieve composite catalyst to the mixture and then performing an ester exchange reaction, followed by a polycondensation reaction, and pouring the product out while hot after the reaction, and cooling to obtain an intermediate product; S3 mixing and stirring the intermediate product, pyridine-type ionic liquid modified hydrotalcite, rubber elastomer, compatibilizer, and antioxidant to obtain a premix; S4 performing melt extrusion, stringing, water cooling, air drying, pelletizing, and drying of the premix in a twin-screw extruder to obtain environmentally friendly polycarbonate;

[0069] The molar ratio of diphenyl carbonate, isosorbide, and bisphenol fluorene is 1:0.6:0.4;

[0070] In step S1, the mixing conditions include: first melting the reactants at 150°C, and then stirring at 500 rpm for 10 minutes at 150°C.

[0071] The weight of the titanium-silicon molecular sieve composite catalyst is 0.02% of the weight of diphenyl carbonate;

[0072] The conditions for the transesterification included: a temperature of 190°C, a pressure of 40 kPa, and a time of 1.5 hours.

[0073] The conditions for the polycondensation reaction include: heating to 290°C, starting the vacuum pump to evacuate the reactor to a pressure of 70 Pa, and reacting for 1.5 hours.

[0074] The preparation method of the titanium-silicon molecular sieve composite catalyst includes: (1) dispersing titanium-silicon molecular sieve in ethanol to obtain a suspension, then adding 3-mercaptopropyltrimethoxysilane for reaction, and after the reaction is completed, cooling the system to room temperature to obtain a material containing mercapto-modified titanium-silicon molecular sieve; (2) adding 1-allyl-3-methylimidazolium hexafluorophosphate and azobisisobutyronitrile to the material containing mercapto-modified titanium-silicon molecular sieve and mixing them at room temperature to obtain a mixture, then loading the mixture into a high-pressure reactor for initiation reaction, and after the reaction is completed, cooling the system to room temperature and centrifuging to obtain a solid precipitate, washing the solid precipitate with water, and then drying to obtain the titanium-silicon molecular sieve composite catalyst;

[0075] In step (1): the dispersion conditions include: dispersion under ultrasonic conditions for 25 minutes;

[0076] In step (1): the reaction conditions include: reacting at 55°C for 1 hour, followed by reflux at 85°C for 6 hours;

[0077] In step (1): the ethanol is used to wash the product 5 times;

[0078] The silicon-to-titanium molar ratio of the titanium-silicon molecular sieve is 46; the average particle size of the titanium-silicon molecular sieve is 1 micrometer, and it was purchased from Auscatalytic Materials (Dalian) Co., Ltd.

[0079] In step (1): the weight ratio of the titanium-silicon molecular sieve to ethanol is 1:150;

[0080] In step (1): the weight ratio of the titanium silicate molecular sieve to 3-mercaptopropyltrimethoxysilane is 1:15;

[0081] The weight ratio of titanium silicate molecular sieve to 1-allyl-3-methylimidazolium hexafluorophosphate is 1:0.35;

[0082] The weight ratio of titanium silicate molecular sieve to azobisisobutyronitrile is 1:0.05;

[0083] In step (2): the conditions for initiating the reaction include: reacting at 100°C for 18 hours;

[0084] In step (2), the drying conditions include: a temperature of 75°C, a vacuum of 0.08 MPa, and a time of 12 hours.

[0085] In step (2): the water washing is performed 4 times;

[0086] The preparation method of pyridine-type ionic liquid modified hydrotalcite includes: dispersing hydrotalcite in anhydrous ethanol, then adding pyridine-type ionic liquid and stirring, then adding silane coupling agent dropwise to react, continuing the reaction for 35 minutes after the addition is complete, then filtering and drying the solid phase to obtain pyridine-type ionic liquid modified hydrotalcite.

[0087] The hydrotalcite was purchased from Kaisma (Dandong) High-Tech Materials Technology Co., Ltd., and its average particle size is 0.6 micrometers.

[0088] The pyridine-type ionic liquid is selected from N-octylpyridine bromide; the coupling agent is selected from KH550; the weight ratio of the hydrotalcite to anhydrous ethanol is 1:30; the weight ratio of the hydrotalcite to the pyridine-type ionic liquid is 1:0.35; the weight ratio of the hydrotalcite to the silane coupling agent is 1:0.04.

[0089] In the preparation of pyridine-type ionic liquid modified hydrotalcite, the silane coupling agent was added dropwise over 35 minutes; the reaction conditions in the preparation of pyridine-type ionic liquid modified hydrotalcite included a temperature of 45°C; the drying conditions in the preparation of pyridine-type ionic liquid modified hydrotalcite included a temperature of 50°C, a vacuum of 0.07 MPa, and a drying time of 6 hours.

[0090] The rubber elastomer is selected from SEBS elastomer; the SEBS elastomer is SEBS G1652 from Kraton, USA, which has a melt index of 5 g / 10 min at 230℃ and 5.0 kg.

[0091] The compatibilizer is styrene-grafted maleic anhydride from Clayville, model SMA1000P.

[0092] The antioxidant is selected from antioxidant 1010;

[0093] The weight ratio of the intermediate product to the pyridine-type ionic liquid modified hydrotalcite is 100:28; the weight ratio of the intermediate product to the rubber elastomer is 100:12; the weight ratio of the intermediate product to the compatibilizer is 100:2; the weight ratio of the intermediate product to the antioxidant is 100:0.2; in step S3, the mixing and stirring conditions include: stirring speed of 1500 rpm and time of 8 minutes; in step S4, the melt extrusion conditions include: temperature control of zones one to eight of the twin-screw extruder as follows: zone one temperature 270℃, zone two temperature 275℃, zone three temperature 275℃, zone four temperature 285℃, zone five temperature 290℃, zone six temperature 290℃, zone seven temperature 290℃ and zone eight temperature 290℃; screw speed 320 rpm.

[0094] Example 2

[0095] This embodiment provides a method for producing environmentally friendly polycarbonate, which includes: S1 adding diphenyl carbonate, isosorbide, and bisphenol fluoride into a reactor under nitrogen atmosphere protection, and then mixing to obtain a mixture; S2 adding a titanium-silicon molecular sieve composite catalyst to the mixture and then performing an ester exchange reaction, followed by a polycondensation reaction, and pouring the product out while hot after the reaction, and cooling to obtain an intermediate product; S3 mixing and stirring the intermediate product, pyridine-type ionic liquid modified hydrotalcite, rubber elastomer, compatibilizer, and antioxidant to obtain a premix; S4 performing melt extrusion, stringing, water cooling, air drying, pelletizing, and drying of the premix in a twin-screw extruder to obtain environmentally friendly polycarbonate;

[0096] The molar ratio of diphenyl carbonate, isosorbide, and bisphenol fluorene is 1:0.5:0.5;

[0097] In step S1, the mixing conditions include: first melting the reactants at 140°C, and then stirring at 500 rpm for 10 minutes at 140°C.

[0098] The weight of the titanium-silicon molecular sieve composite catalyst is 0.01% of the weight of diphenyl carbonate;

[0099] The conditions for the transesterification include: a temperature of 185°C, a pressure of 38 kPa, and a time of 2 hours.

[0100] The conditions for the polycondensation reaction include: heating to 285°C, starting the vacuum pump to evacuate the reactor to a pressure of 70 Pa, and reacting for 1.5 hours.

[0101] The preparation method of the titanium-silicon molecular sieve composite catalyst includes: (1) dispersing titanium-silicon molecular sieve in ethanol to obtain a suspension, then adding 3-mercaptopropyltrimethoxysilane for reaction, and after the reaction is completed, cooling the system to room temperature to obtain a material containing mercapto-modified titanium-silicon molecular sieve; (2) adding 1-allyl-3-methylimidazolium hexafluorophosphate and azobisisobutyronitrile to the material containing mercapto-modified titanium-silicon molecular sieve and mixing them at room temperature to obtain a mixture, then loading the mixture into a high-pressure reactor for initiation reaction, and after the reaction is completed, cooling the system to room temperature and centrifuging to obtain a solid precipitate, washing the solid precipitate with water, and then drying to obtain the titanium-silicon molecular sieve composite catalyst;

[0102] In step (1): the dispersion conditions include: dispersion under ultrasonic conditions for 25 minutes;

[0103] In step (1): the reaction conditions include: reacting at 55°C for 1 hour, followed by reflux at 90°C for 6 hours;

[0104] In step (1): the ethanol is used to wash the product 5 times;

[0105] The silicon-to-titanium molar ratio of the titanium-silicon molecular sieve is 46; the average particle size of the titanium-silicon molecular sieve is 1 micrometer, and it was purchased from Auscatalytic Materials (Dalian) Co., Ltd.

[0106] In step (1): the weight ratio of the titanium-silicon molecular sieve to ethanol is 1:200;

[0107] In step (1): the weight ratio of the titanium silicate molecular sieve to 3-mercaptopropyltrimethoxysilane is 1:10;

[0108] The weight ratio of titanium silicate molecular sieve to 1-allyl-3-methylimidazolium hexafluorophosphate is 1:0.3;

[0109] The weight ratio of titanium silicate molecular sieve to azobisisobutyronitrile is 1:0.05;

[0110] In step (2): the conditions for initiating the reaction include: reacting at 100°C for 18 hours;

[0111] In step (2), the drying conditions include: a temperature of 75°C, a vacuum of 0.08 MPa, and a time of 12 hours.

[0112] In step (2): the water washing is performed 4 times;

[0113] The preparation method of pyridine-type ionic liquid modified hydrotalcite includes: dispersing hydrotalcite in anhydrous ethanol, then adding pyridine-type ionic liquid and stirring, then adding silane coupling agent dropwise to react, continuing the reaction for 35 minutes after the addition is complete, then filtering and drying the solid phase to obtain pyridine-type ionic liquid modified hydrotalcite.

[0114] The hydrotalcite was purchased from Kaisma (Dandong) High-Tech Materials Technology Co., Ltd., and its average particle size is 0.6 micrometers.

[0115] The pyridine-type ionic liquid is selected from N-octylpyridine bromide; the coupling agent is selected from KH550; the weight ratio of the hydrotalcite to anhydrous ethanol is 1:40; the weight ratio of the hydrotalcite to the pyridine-type ionic liquid is 1:0.4; the weight ratio of the hydrotalcite to the silane coupling agent is 1:0.05.

[0116] In the preparation of pyridine-type ionic liquid modified hydrotalcite, the silane coupling agent was added dropwise over 35 minutes; the reaction conditions in the preparation of pyridine-type ionic liquid modified hydrotalcite included a temperature of 45°C; the drying conditions in the preparation of pyridine-type ionic liquid modified hydrotalcite included a temperature of 50°C, a vacuum of 0.07 MPa, and a drying time of 6 hours.

[0117] The rubber elastomer is selected from SEBS elastomer; the SEBS elastomer is SEBS G1652 from Kraton, USA, which has a melt index of 5 g / 10 min at 230℃ and 5.0 kg.

[0118] The compatibilizer is styrene-grafted maleic anhydride from Clayville, model SMA1000P.

[0119] The antioxidant is selected from antioxidant 1010;

[0120] The weight ratio of the intermediate product to the pyridine-type ionic liquid modified hydrotalcite is 100:20; the weight ratio of the intermediate product to the rubber elastomer is 100:20; the weight ratio of the intermediate product to the compatibilizer is 100:2; the weight ratio of the intermediate product to the antioxidant is 100:0.2; in step S3, the mixing and stirring conditions include: stirring speed of 1500 rpm and time of 8 minutes; in step S4, the melt extrusion conditions include: temperature control of zones 1 to 8 of the twin-screw extruder as follows: zone 1 temperature 270℃, zone 2 temperature 275℃, zone 3 temperature 275℃, zone 4 temperature 285℃, zone 5 temperature 290℃, zone 6 temperature 290℃, zone 7 temperature 290℃, and zone 8 temperature 290℃; screw speed 320 rpm.

[0121] Comparative Example 1

[0122] The difference between this comparative example and Example 1 is as follows:

[0123] The titanium-silicon molecular sieve composite catalyst was replaced with a titanium-silicon molecular sieve, with a silicon-to-titanium molar ratio of 46. The average particle size of the titanium-silicon molecular sieve was 1 micrometer, and it was purchased from Auscatalytic Materials (Dalian) Co., Ltd.

[0124] Comparative Example 2

[0125] The difference between this comparative example and Example 1 is as follows:

[0126] The pyridine-type ionic liquid modified hydrotalcite was replaced with hydrotalcite, which was purchased from Kaisma (Dandong) High-tech Materials Technology Co., Ltd., and its average particle size was 0.6 micrometers.

[0127] Comparative Example 3

[0128] The difference between this comparative example and Example 1 is as follows:

[0129] The pyridine-type ionic liquid modified hydrotalcite was replaced with N-octylpyridine bromide.

[0130] Comparative Example 4

[0131] The difference between this comparative example and Example 1 is as follows:

[0132] The pyridine-type ionic liquid is selected from N-ethylpyridine bromide.

[0133] Comparative Example 5

[0134] The difference between this comparative example and Example 1 is as follows:

[0135] No pyridine-type ionic liquid modified hydrotalcite is added during preparation.

[0136] Comparative Example 6

[0137] The difference between this comparative example and Example 1 is as follows:

[0138] No rubber elastomer is added during the preparation process.

[0139] Performance testing

[0140] 1. Colorimetric test: b-value was measured using a HunterLab colorimeter (USA);

[0141] 2. After acclimating the polycarbonate at -50℃ for 5 hours, test the cantilever beam impact strength according to ASTM D256, with a thickness of 3.2 mm.

[0142] 3. The flame retardant properties of polycarbonate were tested according to UL-94 standard.

[0143] 4. Heat distortion temperature test: The test was conducted according to ASTM D648 standard, with a load of 1.82 MPa, a heating rate of 120℃ / h, and a test thickness of 3.2 mm.

[0144] The test results are shown in Table 1.

[0145] Table 1 Performance test results

[0146]

[0147] As can be seen from the above performance test results, the polycarbonate in Examples 1-2 has low color and impact resistance, especially low-temperature impact resistance, and also has excellent flame retardancy and heat resistance. In particular, the comprehensive performance of Example 1 is the most outstanding. It is speculated that this is because the titanium-silicon molecular sieve composite catalyst in this invention can prepare polycarbonate intermediate products with narrow molecular weight distribution. At the same time, the pyridine-type ionic liquid modified hydrotalcite, rubber elastomer and polycarbonate intermediate products work together to achieve the effects of toughening, strengthening and heat resistance.

[0148] The comparative examples, lacking the necessary technical solutions, performed significantly worse than the exemplary examples in relevant performance tests. In Comparative Example 1, the catalyst used a single titanium-silicon molecular sieve, resulting in a significant decrease in the heat resistance of the polycarbonate, demonstrating that the titanium-silicon molecular sieve composite catalyst in this invention more effectively increases the heat resistance of polycarbonate. In Comparative Example 2, replacing the pyridine-type ionic liquid-modified hydrotalcite with a single hydrotalcite significantly reduced the low-temperature toughness and flame retardancy of the polycarbonate, further demonstrating that the pyridine-type ionic liquid-modified hydrotalcite can better increase the low-temperature impact resistance and flame retardancy of polycarbonate. In Comparative Example 3, replacing the pyridine-type ionic liquid-modified hydrotalcite with a pyridine-type ionic liquid significantly reduced the low-temperature toughness and flame retardancy of the polycarbonate, further demonstrating that... This demonstrates that pyridine-type ionic liquid-modified hydrotalcite can better increase the low-temperature impact resistance and flame retardancy of polycarbonate. In Comparative Example 4, where the pyridine-type ionic liquid was N-ethylpyridine, the low-temperature impact resistance of polycarbonate was reduced to some extent, indicating that selecting a specific pyridine-type ionic liquid in this invention can better increase the low-temperature impact resistance of polycarbonate. In Comparative Example 5, the low-temperature impact resistance and heat resistance of polycarbonate without pyridine-type ionic liquid modification were reduced, and in Comparative Example 6, the low-temperature impact resistance and heat resistance of polycarbonate without rubber elastomer were both reduced, indicating that in this invention, pyridine-type ionic liquid-modified hydrotalcite needs to be selected to work synergistically with rubber elastomer to increase the overall performance of polycarbonate.

[0149] The above description represents the preferred embodiments of the present invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for producing environmentally friendly polycarbonate, characterized in that, The production method includes: S1 Diphenyl carbonate, isosorbide and bisphenol fluorene are added to the reactor under nitrogen atmosphere protection, and then mixed to obtain a mixture; S2 After adding the titanium-silicon molecular sieve composite catalyst to the mixture, an ester exchange reaction is carried out, followed by a polycondensation reaction. After the reaction is completed, the product is poured out while hot and then cooled to obtain the intermediate product. S3 involves mixing and stirring the intermediate product, pyridine-type ionic liquid-modified hydrotalcite, rubber elastomer, compatibilizer, and antioxidant to obtain a premix. S4 involves melt extrusion, stringing, water cooling, air drying, pelletizing, and drying of the premix in a twin-screw extruder to obtain environmentally friendly polycarbonate. The preparation method of the titanium-silicon molecular sieve composite catalyst includes: (1) Disperse the titanium silicon molecular sieve in ethanol to obtain a suspension, then add 3-mercaptopropyltrimethoxysilane to react. After the reaction is completed, cool the system to room temperature to obtain the material containing mercapto-modified titanium silicon molecular sieve. (2) 1-Allyl-3-methylimidazolium hexafluorophosphate and azobisisobutyronitrile were added to the material containing mercapto-modified titanium silicate molecular sieve and mixed at room temperature to obtain a mixture. The mixture was then loaded into a high-pressure reactor to initiate the reaction. After the reaction was completed, the system was cooled to room temperature and centrifuged to obtain a solid precipitate. The solid precipitate was washed with water and then dried to obtain a titanium silicate molecular sieve composite catalyst. The preparation method of the pyridine-type ionic liquid modified hydrotalcite includes: dispersing hydrotalcite in anhydrous ethanol, then adding pyridine-type ionic liquid and stirring, then adding silane coupling agent dropwise to react and obtain hydrotalcite. After the addition is complete, continue the reaction for 30-40 minutes, then filter and dry the solid phase to obtain pyridine-type ionic liquid modified hydrotalcite.

2. The production method according to claim 1, characterized in that, The molar ratio of diphenyl carbonate, isosorbide and bisphenol fluorene is 1:(0.5-0.7):(0.3-0.4); in step S1, the mixing conditions include: first melting the reactants at 120-160°C, and then stirring at 500-600 rpm for 5-20 minutes at 120-160°C. The weight of the titanium-silicon molecular sieve composite catalyst is 0.01-0.04% of the weight of diphenyl carbonate; The conditions for the transesterification include: a temperature of 180-190℃, a pressure of 35-45kPa, and a time of 1-2 hours; The conditions for the polycondensation reaction include: heating to 280-300℃, starting the vacuum pump to evacuate the reactor to a pressure of 70-80 Pa, and reacting for 1-2 hours.

3. The production method according to claim 1, characterized in that, In step (1): the dispersion conditions include: dispersion under ultrasonic conditions for 20-30 minutes; the reaction conditions include: reaction at 50-60℃ for 0.5-1 hour, followed by reflux reaction at 80-90℃ for 5-7 hours; and washing with ethanol 3-6 times.

4. The production method according to claim 1, characterized in that, The silicon-to-titanium molar ratio of the titanium-silicon molecular sieve is 30-70:1; the average particle size of the titanium-silicon molecular sieve is 0.2-10 micrometers; the weight ratio of the titanium-silicon molecular sieve to ethanol is 1:(100-200); the weight ratio of the titanium-silicon molecular sieve to 3-mercaptopropyltrimethoxysilane is 1:(10-20); the weight ratio of the titanium-silicon molecular sieve to 1-allyl-3-methylimidazolium hexafluorophosphate is 1:(0.1-1); and the weight ratio of the titanium-silicon molecular sieve to azobisisobutyronitrile is 1:(0.01-0.1).

5. The production method according to claim 1, characterized in that, In step (2): the conditions for initiating the reaction include: reacting at 95-120℃ for 15-20 hours; the drying conditions include: temperature of 70-80℃, vacuum degree of 0.07-0.09MPa, time of 8-20 hours; and washing with water 3-5 times.

6. The production method according to claim 1, characterized in that, The average particle size of the hydrotalcite is 0.1-2 micrometers; the pyridine-type ionic liquid is selected from N-C2-C10 alkylpyridine bromide; the coupling agent is selected from at least one of KH550, KH560, KH580, KH590, KH602 and KH792; the weight ratio of hydrotalcite to anhydrous ethanol is 1:(20-40); the weight ratio of hydrotalcite to pyridine-type ionic liquid is 1:(0.2-1); the weight ratio of hydrotalcite to silane coupling agent is 1:(0.05-0.1); the reaction conditions include a temperature of 40-45℃.

7. The production method according to claim 1, characterized in that, The rubber elastomer is selected from SEBS elastomer; the compatibilizer is selected from styrene-grafted maleic anhydride and / or polystyrene-grafted glycidyl methacrylate; the antioxidant is selected from at least one of antioxidant 1010, antioxidant 1076, antioxidant 1098, antioxidant 2246, antioxidant 264, antioxidant 300, antioxidant 442, antioxidant BHT, and antioxidant DSTP; the weight ratio of the intermediate product to the pyridine-type ionic liquid modified hydrotalcite is 100:(25-30); the weight ratio of the intermediate product to the rubber elastomer is 100:(10-15); the weight ratio of the intermediate product to the compatibilizer is 100:(1-3); the weight ratio of the intermediate product to the antioxidant is 100:(0.1-0.3).

8. The production method according to any one of claims 1-7, characterized in that, In step S3, the mixing conditions include: a stirring speed of 1200-2000 rpm and a time of 5-10 minutes; in step S4, the melt extrusion conditions include: temperature control of zones 1 to 8 of the twin-screw extruder as follows: zone 1 temperature 260-280℃, zone 2 temperature 270-290℃, zone 3 temperature 270-290℃, zone 4 temperature 280-300℃, zone 5 temperature 280-300℃, zone 6 temperature 280-300℃, zone 7 temperature 280-300℃, and zone 8 temperature 280-300℃; screw speed 300-400 rpm.

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