Preparation method of fluorine-free environment-friendly flame-retardant polycarbonate

Abstract

The invention discloses a preparation method of fluorine-free environment-friendly flame-retardant polycarbonate, and belongs to the technical field of high polymer materials. The preparation method comprises the following steps: weighing 60-70 parts by weight of polycarbonate resin, 10-20 parts by weight of a filler, 1-3 parts by weight of a modified coupling agent, 12-18 parts by weight of a flame retardant, 5-8 parts by weight of a flexibilizer, 2-5 parts by weight of a compatilizer and 0.5-2 parts by weight of a lubricant, sequentially adding into a high-speed mixer for stirring and mixing, discharging after uniformly mixing, adding into a double-screw extruder, melting, mixing, extruding, cooling and granulating to obtain the flame-retardant polycarbonate material. The fluorine-free environment-friendly flame-retardant polycarbonate is obtained. The modified coupling agent containing the hindered phenol structure not only has chemical action with the filler, but also has chemical action with the flame retardant, so that the filler and the flame retardant stably exist under the action of the modified coupling agent and are highly dispersed in the polycarbonate, and the polycarbonate has excellent and stable flame retardant property and mechanical property, and also has excellent flame retardant property and flame retardant property. The anti-aging performance is excellent and stable, and the comprehensive performance is excellent.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer materials, and specifically relates to a preparation method of an environmentally friendly flame-retardant polycarbonate without fluorine. Background Art

[0002] Polycarbonate (PC) is one of the five widely used engineering plastics, with high impact resistance and heat resistance characteristics, and is widely used in the fields of electronics, electrical appliances, automobiles, aerospace, etc. In recent years, with the expansion of the application fields and production scale of polycarbonate, people's requirements for its performance have become higher and higher, especially for the flame retardancy and strength performance of materials. However, due to the flame retardancy of the PC material itself, it can generally only reach the V-2 level in the UL94 standard, with only certain flame retardant characteristics. With the application requirements of various industries, this flame retardant level far cannot meet the performance requirements of the UL94 V-0 level, and the molten heat generated when PC burns is also very easy to cause secondary combustion of nearby materials. Therefore, it is necessary to carry out flame retardant modification on the PC material and ensure other properties of the material.

[0003] Chinese Patent CN104725821A discloses a phosphorus-nitrogen-based halogen-free flame-retardant polycarbonate and its preparation method. The components of the phosphorus-nitrogen-based halogen-free flame-retardant polycarbonate are proportioned by mass percentage as follows: polycarbonate 60%-85%, phosphorus-nitrogen-based halogen-free flame retardant 5%-10%, reinforcing agent 5%-20%, compatibilizer 2%-5%, anti-dripping agent 0.1%-1%, lubricant 0.1%-1.5%. The phosphorus-nitrogen-based halogen-free flame-retardant polycarbonate prepared by this invention not only has high strength, good heat resistance and dimensional stability, but also has good processability and flame retardancy. Its vertical combustion can reach the V-0 level, and it also has characteristics such as good thermal stability, hydrolysis stability and excellent electrical properties. However, this phosphorus-nitrogen-based halogen-free flame-retardant polycarbonate uses a polytetrafluoroethylene-based anti-dripping agent, and the main components of this anti-dripping agent contain perfluoroalkyl or polyfluoroalkyl substances, and polyfluoroalkyl substances have persistence, long-distance migration, toxicity and bioaccumulation. Therefore, it is necessary to develop a polycarbonate without fluorine, environmentally friendly and with excellent flame retardancy. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the prior art and provide a preparation method of an environmentally friendly flame-retardant polycarbonate without fluorine.

[0005] The purpose of the present invention can be achieved by the following technical solutions: A preparation method of an environmentally friendly flame-retardant polycarbonate without fluorine, comprising the following steps: Weigh 60 - 70 parts by weight of polycarbonate resin, 10 - 20 parts of filler, 1 - 3 parts of modified coupling agent, 12 - 18 parts of flame retardant, 5 - 8 parts of toughening agent, 2 - 5 parts of compatibilizer, and 0.5 - 2 parts of lubricant in sequence. Then add them to a high - speed mixer and stir - mix. After mixing evenly, discharge the mixture, and then add it to a twin - screw extruder for melt - mixing extrusion, followed by cooling and pelletizing to obtain fluorine - free environmentally friendly flame - retardant polycarbonate.

[0006] Further, the filler is one or more of silica, nano - calcium carbonate, magnesium hydroxide, aluminum hydroxide, nano - titanium dioxide, glass fiber, and talc powder.

[0007] Further, the modified coupling agent is prepared through the following steps: (1) Replace the air and moisture in a dry three - necked flask with nitrogen. Then add 3,5 - di - tert - butyl - 4 - hydroxybenzyl alcohol, dibutyltin dilaurate, and DMSO (dimethyl sulfoxide), stir evenly, and slowly add 3 - isocyanatopropyltrimethoxysilane. Then raise the temperature to 60 °C and stir - react for 1 h. After the reaction is completed, cool to room temperature, perform vacuum distillation, and purify by column chromatography (the eluent uses a mixed solvent of benzene and methanol, and the volume ratio of benzene to methanol is 95:5). Finally, remove the eluent by vacuum distillation. The whole process is carried out under nitrogen protection to obtain intermediate 1. The dosage ratio of 3,5 - di - tert - butyl - 4 - hydroxybenzyl alcohol, 3 - isocyanatopropyltrimethoxysilane, dibutyltin dilaurate, and DMSO is 37 g:28 mL:2.7 mL:200 mL; Under the catalysis of dibutyltin dilaurate, control the molar ratio of 3,5 - di - tert - butyl - 4 - hydroxybenzyl alcohol to 3 - isocyanatopropyltrimethoxysilane to be 1.05 - 1.1:1. The hydroxyl group of 3,5 - di - tert - butyl - 4 - hydroxybenzyl alcohol and the isocyanate group of 3 - isocyanatopropyltrimethoxysilane undergo an addition reaction at room temperature. The reaction equation is as follows:

[0008] (2) Blow nitrogen into the dry three - necked flask for 30 min to remove air and moisture. Add intermediate 1, tetra - isopropyl titanate, and benzene to the above - mentioned flask, stir to dissolve, and then slowly add glycidol. After adding, raise the temperature to 90 °C and react for 24 h. After the reaction is completed, cool to room temperature, perform vacuum distillation, and purify by column chromatography (the eluent uses a mixed solvent of benzene and ether, and the volume ratio of benzene to ether is 6:4). Finally, remove the eluent by vacuum distillation. The whole process is carried out under nitrogen protection to obtain the modified coupling agent. The dosage ratio of intermediate 1, glycidol, tetra - isopropyl titanate, and benzene is 61.5 g:9 g:0.8 mL:250 mL.

[0009] Under the catalysis of tetraisopropyl titanate, the molar ratio of intermediate 1 to glycidol is controlled to be 1.1 - 1.2:1, and the following chemical reaction occurs between the silaneoxy group of intermediate 1 and the hydroxyl group of glycidol. The reaction process is as follows:

[0010] The modified coupling agent of the present invention has silaneoxy groups on its surface. After hydrolysis and condensation, Si-OH and Si-O-Si are generated. The hydroxyl groups in Si-OH can form chemical bonds with the hydroxyl groups on the surfaces of fillers such as nano-calcium carbonate and magnesium hydroxide. Furthermore, the modified coupling agent can play a role in dispersing and stabilizing the fillers.

[0011] The surface of the modified coupling agent is also grafted with a hindered phenol antioxidant structure. The hindered phenol antioxidant structure is a type of compound with substituent groups on one or both sides of -OH on the benzene ring. In most cases, its structure includes two tert-butyl groups. Due to the spatial hindrance of the hydroxyl group, the hydrogen atom can easily fall off from the original molecular structure, thereby achieving the effect of donating a proton and combining with peroxy radicals, alkyl radicals, hydroxyl radicals, etc., causing them to lose their original activity, thus terminating the aging reaction. Therefore, adding the modified coupling agent of the present invention into the polycarbonate material can also effectively improve the anti-aging ability of the material.

[0012] In addition, the surface of the modified coupling agent also contains epoxy groups, which can have a chemical reaction with the terminal amino group of the flame retardant molecule under heating conditions. Therefore, the modified coupling agent of the present invention can not only further stably exist in the polycarbonate material, play the role of dispersing fillers and anti-aging, making the mechanical properties and anti-aging properties of the polycarbonate material more stable and lasting, but also stabilize the flame retardant, enabling the flame retardant to fully play the role of flame retardancy and smoke suppression.

[0013] Furthermore, the flame retardant is prepared through the following steps: S1. Under nitrogen protection, dissolve diethylphosphonoacetic acid and 2-chloro-4,6-diamino-1,3,5-triazine in DMF (N,N-dimethylformamide), add EDC (1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride) and NHS (N-hydroxysuccinimide), mix evenly, then raise the temperature to 50 °C and stir for 6 h. After the reaction is completed, cool to room temperature, perform vacuum distillation, and purify by column chromatography (select a mixed solvent of cyclohexane and ethyl acetate as the eluent, and the volume ratio of cyclohexane to ethyl acetate is 1:1), and then perform vacuum distillation to obtain intermediate 2. The dosage ratio of diethylphosphonoacetic acid, 2-chloro-4,6-diamino-1,3,5-triazine, EDC, NHS, and DMF is 52 mL:22 g:0.6 g:0.4 g:250 mL; Control the molar ratio of diethylphosphonoacetic acid to 2-chloro-4,6-diamino-1,3,5-triazine to be 2.1-2.2:1. Under the action of EDC and NHS, the -COOH of diethylphosphonoacetic acid reacts with the -NH of 2-chloro-4,6-diamino-1,3,5-triazine 2 to undergo an amidation reaction, and the reaction equation is as follows:

[0014] S2. Add intermediate 2, triethylamine, and DMF to a sufficiently dried three-necked flask. After stirring evenly, add 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane. After the addition, stir and react at room temperature for 3 h. After the reaction is completed, perform vacuum distillation to obtain the flame retardant; the dosage ratio of intermediate 2, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, triethylamine, and DMF is 50 g:29.5 mL:16.6 mL:250 mL.

[0015] Control the molar ratio of intermediate 2 to 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane to be 1:1.05-1.1. The -Cl of intermediate 2 reacts with the -NH of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane 2 to undergo a nucleophilic substitution reaction, with triethylamine as the acid-binding agent. The reaction process is as follows:

[0016] In the flame retardant of the present invention, the phosphorus element provides an acid source, acts on the polymer material, and promotes the formation of carbide; the nitrogen element provides a gas source, which can cause the system to expand and foam, and also promotes the formation of the carbonized layer, forming a porous foam carbon; the silicon element generates an inorganic heat-insulating and insulating protective layer containing -Si-O bonds and -Si-C- bonds during combustion, which not only prevents the decomposition products generated by combustion from escaping, but also inhibits the thermal decomposition of the polymer material, achieving the purpose of high flame retardancy, low smoke generation, and low harmfulness. The flame retardant of the present invention exerts a highly efficient and safe flame retardant effect through the synergistic effect of nitrogen, phosphorus, and silicon halogen-free flame retardant elements. The flame retardant of the present invention and fillers such as magnesium hydroxide and aluminum hydroxide act synergistically, making the polycarbonate of the present invention have excellent flame retardancy and smoke suppression properties. In addition, there is a chemical interaction between the flame retardant and the modified coupling agent, and there is a chemical interaction between the modified coupling agents and the fillers. Therefore, both the flame retardant and the fillers can exist more stably in the polycarbonate material. Therefore, the flame retardancy and smoke suppression properties of the polycarbonate of the present invention are more stable and lasting.

[0017] Further, the toughening agent is one or more of polybutylene succinate, polybutylene adipate, polyethylene succinate, and ethylene-vinyl acetate copolymer.

[0018] Further, the compatibilizer is one or two of styrene - maleic anhydride copolymer and styrene - acrylonitrile - glycidyl methacrylate copolymer.

[0019] Further, the lubricant is pentaerythritol stearate.

[0020] Advantages of the present invention: The modified coupling agent containing a hindered phenol structure has both a chemical interaction with the filler and a chemical interaction with the flame retardant. Therefore, the filler and the flame retardant of the present invention are stably present and highly dispersed in the polycarbonate under the action of the modified coupling agent. Thus, the polycarbonate of the present invention not only has excellent and stable flame retardant properties and mechanical properties, but also has excellent and stable anti - aging properties. At the same time, it does not contain fluorine, is environmentally friendly and has excellent comprehensive properties, having broad market application prospects. Specific embodiments

[0021] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without making creative efforts belong to the scope of protection of the present invention.

[0022] Example 1, preparing a modified coupling agent, the specific steps are as follows: (1) Replace the air and moisture in a 500 mL dry three - necked flask with nitrogen, then add 37 g of 3,5 - di - tert - butyl - 4 - hydroxybenzyl alcohol, 2.7 mL of dibutyltin dilaurate and 200 mL of DMSO. After stirring evenly, slowly add 28 mL of 3 - isocyanatopropyltrimethoxysilane, then raise the temperature to 60 °C and stir for 1 h. After the reaction is completed, cool to room temperature, carry out reduced - pressure distillation, and purify by column chromatography (the eluent uses a mixed solvent of benzene and methanol, and the volume ratio of benzene to methanol is 95:5). Finally, remove the eluent by reduced - pressure distillation. The whole process is carried out under nitrogen protection to obtain intermediate 1; (2) Blow nitrogen into a 500 mL dry three - necked flask for 30 min to remove air and moisture. Add 61.5 g of intermediate 1, 0.8 mL of tetra - isopropyl titanate and 250 mL of benzene into the above flask. After stirring and dissolving, slowly add 9 g of glycidol. After adding, raise the temperature to 90 °C and react for 24 h. After the reaction is completed, cool to room temperature, carry out reduced - pressure distillation, and purify by column chromatography (the eluent uses a mixed solvent of benzene and ether, and the volume ratio of benzene to ether is 6:4). Finally, remove the eluent by reduced - pressure distillation. The whole process is carried out under nitrogen protection to obtain the modified coupling agent.

[0023] Example 2, preparing a flame retardant, the specific steps are as follows: S1. Under nitrogen protection, 52 mL of diethylphosphonoacetic acid and 22 g of 2-chloro-4,6-diamino-1,3,5-triazine were dissolved in 250 mL of DMF, 0.6 g of EDC and 0.4 g of NHS were added, and after mixing evenly, the temperature was raised to 50 °C and stirred for reaction for 6 h. After the reaction was completed, it was cooled to room temperature, distilled under reduced pressure, and purified by column chromatography (the eluent was a mixed solvent of cyclohexane and ethyl acetate, and the volume ratio of cyclohexane to ethyl acetate was 1:1), and then distilled under reduced pressure to obtain intermediate 2; S2. 50 g of intermediate 2, 16.6 mL of triethylamine and 250 mL of DMF were added to a 500 mL fully dried three-necked flask, and after stirring evenly, 29.5 mL of 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane was added. After the addition, it was stirred at room temperature for reaction for 3 h. After the reaction was completed, it was distilled under reduced pressure to obtain the flame retardant.

[0024] Example 3. Preparation of fluorine-free polycarbonate, the specific steps are as follows: Weigh 60 parts of polycarbonate resin, 5 parts of white carbon black, 5 parts of magnesium hydroxide, 1 part of the modified coupling agent prepared in Example 1, 12 parts of the flame retardant prepared in Example 2, 5 parts of polybutylene succinate, 2 parts of styrene-maleic anhydride copolymer and 0.5 part of pentaerythritol stearate by weight, and then add them to a high-speed mixer in turn and stir. After mixing evenly, discharge, then add to a twin-screw extruder, melt and mix and extrude, and cool and pelletize to obtain fluorine-free polycarbonate.

[0025] Example 4. Preparation of fluorine-free polycarbonate, the specific steps are as follows: Weigh 65 parts of polycarbonate resin, 10 parts of nano calcium carbonate, 5 parts of aluminum hydroxide, 2 parts of the modified coupling agent prepared in Example 1, 16 parts of the flame retardant prepared in Example 2, 3 parts of polybutylene adipate, 3 parts of polyethylene succinate glycol, 3 parts of styrene-acrylonitrile-methylacrylic acid glycerol ester copolymer and 1 part of pentaerythritol stearate by weight, and then add them to a high-speed mixer in turn and stir. After mixing evenly, discharge, then add to a twin-screw extruder, melt and mix and extrude, and cool and pelletize to obtain fluorine-free polycarbonate.

[0026] Example 5. Preparation of fluorine-free polycarbonate, the specific steps are as follows: Weigh 70 parts of polycarbonate resin, 5 parts of magnesium hydroxide, 5 parts of nano-titanium dioxide, 5 parts of glass fiber, 5 parts of talcum powder, 3 parts of the modified coupling agent prepared in Example 1, 18 parts of the flame retardant prepared in Example 2, 4 parts of polyethylene glycol succinate, 4 parts of ethylene-vinyl acetate copolymer, 5 parts of styrene-acrylonitrile-methylacrylic acid glycerol ester copolymer, and 2 parts of pentaerythritol stearate by weight. Then, add them to a high-speed mixer in sequence and stir. After mixing evenly, discharge the mixture, and then add it to a twin-screw extruder for melt mixing and extrusion. After cooling and pelletizing, a fluorine-free polycarbonate is obtained.

[0027] Comparative Example 1: Prepare a fluorine-free polycarbonate. The specific steps are as follows: Keep the other steps unchanged, and only replace the modified coupling agent in Example 3 with 0.5 part of antioxidant 1035 and 0.5 part of 3-aminopropyltrimethoxysilane to prepare a fluorine-free polycarbonate.

[0028] Comparative Example 2: Prepare a fluorine-free polycarbonate. The specific steps are as follows: Keep the other steps unchanged, and only replace the flame retardant in Example 3 with 12 parts of ammonium polyphosphate flame retardant to prepare a fluorine-free polycarbonate.

[0029] Performance Test Make specimens of the fluorine-free polycarbonates prepared in Examples 3-5 and Comparative Examples 1-2 according to the corresponding standards, and conduct the following performance tests: The combustion rating test is carried out according to the standard of UL94-2018; the limiting oxygen index test is carried out according to the standard of ISO4589-2; the performance tests of tensile strength and elongation at break are carried out according to the standard of ASTM-D638; dry heat aging is carried out at 105°C for 120 h, and then the tensile strength and elongation at break are tested according to the standard of ASTM-D638. The test results of all items are shown in the following table:

[0030] In the description of the specification, the description referring to terms such as "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples.

[0031] The above content is only an example and illustration of the present invention. Those skilled in the art of this technology can make various modifications or supplements to the described specific embodiments or use similar methods for substitution, as long as they do not deviate from the invention or exceed the scope defined by the claims of this patent, they should fall within the protection scope of the present invention.

Claims

1. A method for preparing a fluorine-free, environmentally friendly, flame-retardant polycarbonate, characterized in that: The following steps are involved: Weigh 60-70 parts of polycarbonate resin, 10-20 parts of filler, 1-3 parts of modified coupling agent, 12-18 parts of flame retardant, 5-8 parts of toughening agent, 2-5 parts of compatibilizer and 0.5-2 parts of lubricant by weight, add them into a high-speed mixer for stirring, mix them evenly and discharge them, add them into a twin-screw extruder, melt-mix and extrude them, cool and granulate them to obtain fluorine-free environmentally friendly flame-retardant polycarbonate; Wherein, the modified coupling agent is prepared by the following steps: (1) The air and moisture in the flask were replaced with nitrogen, 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, dibutyltin dilaurate and DMSO were added, 3-isocyanatepropyltrimethoxysilane was added after stirring, the temperature was raised to 60°C and the reaction was continued for 1 hour. After the reaction was completed, the mixture was cooled to room temperature, vacuum distilled, purified by column chromatography, and vacuum distilled to obtain intermediate 1; (2) Blow nitrogen into a flask, add intermediate 1, tetraisopropyl titanate and benzene, stir and add glycidol, raise the temperature to 90°C and react for 24 hours, cool to room temperature after the reaction is completed, distill under reduced pressure, purify by column chromatography, and distill under reduced pressure to obtain a modified coupling agent; The flame retardant is prepared by the following steps: S1, under nitrogen protection, diethylphosphoacetic acid and 2-chloro-4,6-diamino-1,3,5-triazine were dissolved in DMF, and EDC and NHS were added, mixed, heated to 50°C and reacted for 6 hours, cooled to room temperature after the reaction, distilled under reduced pressure, purified by column chromatography, and distilled under reduced pressure to obtain intermediate 2; S2. Add intermediate 2, triethylamine and DMF into a flask, stir and then add 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane. After the addition is complete, stir and react at room temperature for 3 hours. After the reaction is completed, distill under reduced pressure to obtain a flame retardant.

2. The method for preparing a fluorine-free, environmentally friendly, flame-retardant polycarbonate according to claim 1, characterized in that: The usage ratio of 3,5-di-tert-butyl-4-hydroxybenzyl alcohol, 3-isocyanatepropyltrimethoxysilane, dibutyltin dilaurate and DMSO in step (1) is 37 g:28 mL:2.7 mL:200 mL.

3. The method for preparing a fluorine-free, environmentally friendly, flame-retardant polycarbonate according to claim 1, characterized in that: The usage ratio of the intermediate 1, glycidol, tetraisopropyl titanate and benzene in the step (2) is 61.5 g:9 g:0.8 mL:250 mL.

4. The method for preparing a fluorine-free, environmentally friendly, flame-retardant polycarbonate according to claim 1, characterized in that: The ratio of the amount of diethylphosphoacetic acid, 2-chloro-4,6-diamino-1,3,5-triazine, EDC, NHS and DMF used in step S1 is 52 mL: 22 g: 0.6 g: 0.4 g: 250 mL.

5. The method for preparing a fluorine-free, environmentally friendly, flame-retardant polycarbonate according to claim 1, characterized in that: The usage ratio of the intermediate 2, 1,3-bis(3-aminopropyl)-1,1,3,3-tetramethyldisiloxane, triethylamine and DMF in step S2 is 50 g:29.5 mL:16.6 mL:250 mL.

6. The method for preparing a fluorine-free, environmentally friendly, flame-retardant polycarbonate according to claim 1, characterized in that: The filler is one or more of white carbon black, nano calcium carbonate, magnesium hydroxide, aluminum hydroxide, nano titanium dioxide, glass fiber and talcum powder.

7. The method for preparing a fluorine-free, environmentally friendly, flame-retardant polycarbonate according to claim 1, characterized in that: The toughening agent is one or more of polybutylene succinate, polybutylene adipate, polyethylene succinate and ethylene-vinyl acetate copolymer.

8. The method for preparing a fluorine-free, environmentally friendly, flame-retardant polycarbonate according to claim 1, characterized in that: The compatibilizer is one or two of styrene-maleic anhydride copolymer and styrene-acrylonitrile-methacrylate copolymer.

9. The method for preparing a fluorine-free, environmentally friendly, flame-retardant polycarbonate according to claim 1, characterized in that: The lubricant is pentaerythritol stearate.

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