A heat-resistant polycarbonate and its preparation method

Abstract

This invention relates to the field of polycarbonate technology and discloses a heat-resistant polycarbonate and its preparation method. The invention involves mixing bisphenol A, bisphenol functional monomers, sodium hydroxide, triethylamine, and water, then adding a dichloromethane solution containing triphosgene dropwise to react and obtain heat-resistant polycarbonate. Polyarylamide structural units and diphenylacetylene structures are introduced into the polycarbonate molecular backbone. The polyarylamide possesses high modulus and high strength, while the amide bonds form hydrogen bonds, enhancing the intermolecular interactions and improving tensile strength and mechanical properties. Diphenylacetylene exhibits high char-forming ability; at high temperatures, the acetylene group and aromatic ring readily crosslink to form a fused ring structure, significantly improving the heat resistance of the polycarbonate and increasing its thermal decomposition temperature. This results in polycarbonate possessing both excellent heat resistance, high-temperature resistance, and mechanical strength.

Description

Technical Field

[0001] This invention relates to the field of polycarbonate technology, specifically to a heat-resistant polycarbonate and its preparation method. Background Technology

[0002] Polycarbonate is a high-performance resin material with excellent dimensional stability, mechanical strength, and toughness, and is widely used in optical instruments, medical devices, and electronic appliances. The main methods for preparing polycarbonate include phosgene interfacial polycondensation and non-phosgene melt transesterification. Phosgene interfacial polycondensation uses phosgene, bisphenol A, and other raw materials for polymerization, offering advantages such as mild reaction, easily controllable molecular weight, high transparency, and high impact resistance. However, phosgene is highly toxic and poses significant health risks. Triphosgene, on the other hand, has high stability and low toxicity, and can be used as a substitute for phosgene in the preparation of polycarbonate.

[0003] In the preparation of polycarbonate, the addition of functional monomers such as bisphenol S, tetrabromobisphenol A, and organosilicon phenolic compounds can produce functional polycarbonates with high temperature resistance, flame retardancy, and high toughness. Patent CN115490842B discloses a copolymer flame-retardant polycarbonate and its preparation method. The copolymer flame-retardant polycarbonate obtained by polycondensation of bisphenol A, diphenyl carbonate, and phosphorus-containing flame-retardant monomers exhibits excellent flame-retardant properties. However, phosphorus compounds typically have low thermal decomposition temperatures, which can affect the material's heat resistance and high-temperature performance. Summary of the Invention

[0004] To address the shortcomings of existing technologies, the technical problem solved by this invention is to significantly improve the heat resistance, high-temperature resistance, and mechanical properties of polycarbonate.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a method for preparing heat-resistant polycarbonate: adding bisphenol A, bisphenol functional monomer, sodium hydroxide, triethylamine and water to a flask, stirring and mixing, adding a dichloromethane solution containing triphosgene dropwise and reacting, adding water for extraction, removing the aqueous phase, adding ethanol to the dichloromethane organic phase for precipitation, filtering and washing the precipitate with ethanol and water, drying to obtain heat-resistant polycarbonate; Furthermore, the molar ratio of bisphenol A, bisphenol functional monomer, sodium hydroxide, triethylamine, and triphosgene is (80-97):(3-20):(220-260):(7-10):(38-42).

[0006] Furthermore, the dropping time for the dichloromethane solution containing triphosgene is 30-40 minutes.

[0007] Furthermore, the reaction temperature is 20-30℃ and the reaction time is 20-30 min.

[0008] Furthermore, the stirring speed is 300-800 r / min.

[0009] Furthermore, the preparation method of the bisphenol functional monomer is as follows: (1) Add tetrahydrofuran, bis(4-aminophenyl)acetylene, triethylamine and p-methoxybenzoyl chloride to a flask, react, filter and distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain the precursor.

[0010] (2) Add dichloromethane and precursor to the flask, purge with nitrogen, and add dichloromethane solution containing boron tribromide dropwise in an ice-water bath to carry out the reaction. After the reaction, add methanol to quench excess boron tribromide, stir, add sodium hydroxide aqueous solution, stir, add dichloromethane for extraction, dry the dichloromethane organic phase with anhydrous magnesium sulfate, filter, distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain bisphenol functional monomer.

[0011] Furthermore, in (1), the reaction temperature is 60-70℃ and the reaction time is 4-6h.

[0012] Furthermore, in (1), the molar ratio of bis(4-aminophenyl)acetylene, triethylamine, and p-methoxybenzoyl chloride is 1:(2-2.1):(2-2.4).

[0013] Furthermore, in (2), the reaction temperature is 20-30℃ and the reaction time is 5-8h.

[0014] Furthermore, in (2), the molar ratio of the precursor to boron tribromide is 1:(5-6.2).

[0015] The beneficial technical effects of adopting the above technical solution are as follows: The copolymerization reaction of bisphenol functional monomers with bisphenol A introduces polyarylamide structural units and diphenylacetylene structures into the polycarbonate molecular backbone. Polyarylamides possess high modulus and high strength, while hydrogen bonds between amide bonds enhance the intermolecular chain interactions, thus improving tensile strength and mechanical properties. Diphenylacetylene exhibits high char-forming ability; at high temperatures, the acetylene group and aromatic ring readily undergo thermal cross-linking to form a fused ring structure, significantly improving the heat resistance of polycarbonate and increasing its thermal decomposition temperature. This gives polycarbonate both excellent heat resistance and high-temperature resistance, as well as good mechanical strength. Detailed Implementation

[0016] To facilitate understanding of the present invention, a more comprehensive description is provided below. The invention can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a thorough and complete understanding of the disclosure of the present invention.

[0017] Bis(4-aminophenyl)acetylene was prepared according to the literature Tetrahedron, 2004, vol. 60, # 44, p. 9977, "Sonogashira coupling with aqueous ammonia directed to the synthesis of azotolane derivatives".

[0018] Example 1, a method for preparing heat-resistant polycarbonate: (1) Add 200 mL of tetrahydrofuran, 60 mmol of bis(4-aminophenyl)acetylene, 120 mmol of triethylamine and 132 mmol of p-methoxybenzoyl chloride to a flask, heat to 65 °C, stir and reflux for 6 h, filter and distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain the precursor.

[0019] (2) Add 350 mL of dichloromethane and 50 mmol of precursor to a flask, purge with nitrogen, and add 170 mL of dichloromethane solution containing 310 mmol of boron tribromide dropwise in an ice-water bath. Stir the reaction at 20 °C for 7 h, add methanol, stir, add 0.5% sodium hydroxide aqueous solution, stir, add dichloromethane for extraction, dry the dichloromethane organic phase with anhydrous magnesium sulfate, filter, distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain the bisphenol functional monomer. The reaction formula is as follows: .

[0020] (3) Add 970 mmol bisphenol A, 30 mmol bisphenol functional monomer, 2.3 mol sodium hydroxide, 70 mmol triethylamine, and 1.3 L water to a flask, stir and mix for 20 min, controlling the stirring speed at 500 r / min; add 2.2 L of dichloromethane solution containing 420 mmol triphosgene dropwise, controlling the dropwise addition time at 30 min. After the dropwise addition is complete, continue stirring the reaction at 25 °C for 30 min, add water for extraction, remove the aqueous phase, add ethanol to the dichloromethane organic phase for precipitation, filter, wash the precipitate with ethanol and water, dry, and obtain heat-resistant polycarbonate. The reaction formula is as follows: .

[0021] Example 2, a method for preparing heat-resistant polycarbonate: (1) Add 700 mL of tetrahydrofuran, 200 mmol of bis(4-aminophenyl)acetylene, 400 mmol of triethylamine and 400 mmol of p-methoxybenzoyl chloride to a flask, heat to 70 °C, stir and reflux for 4 h, filter and distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain the precursor.

[0022] (2) Add 1L of dichloromethane and 150mmol of precursor to a flask, purge with nitrogen, add 450mL of dichloromethane solution containing 810mmol of boron tribromide dropwise in an ice-water bath, stir at 20°C for 8h, add methanol, stir, add 0.5% sodium hydroxide aqueous solution, stir, add dichloromethane for extraction, dry the dichloromethane organic phase with anhydrous magnesium sulfate, filter, distill the filtrate under reduced pressure, separate the mixture by silica gel column chromatography to obtain bisphenol functional monomer.

[0023] (3) Add 900 mmol bisphenol A, 100 mmol bisphenol functional monomer, 2.2 mol sodium hydroxide, 100 mmol triethylamine and 1.3 L water to the flask, stir and mix for 20 min, and control the stirring speed to 800 r / min; add 2 L of dichloromethane solution containing 380 mmol triphosgene dropwise, and control the dropwise addition time to 40 min. After the dropwise addition is completed, continue to stir the reaction at 20 °C for 30 min, add water to extract, remove the aqueous phase, add ethanol to the dichloromethane organic phase to precipitate, filter and wash the precipitate with ethanol and water, dry, and obtain heat-resistant polycarbonate.

[0024] Example 3, a method for preparing heat-resistant polycarbonate: (1) Add 900 mL of tetrahydrofuran, 270 mmol of bis(4-aminophenyl)acetylene, 567 mmol of triethylamine and 540 mmol of p-methoxybenzoyl chloride to a flask, heat to 60 °C, stir and reflux for 6 h, filter and distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain the precursor.

[0025] (2) Add 1.2 L of dichloromethane and 200 mmol of precursor to a flask, purge with nitrogen, add 550 mL of dichloromethane solution containing 1 mol of boron tribromide dropwise in an ice-water bath, stir at 30 °C for 5 h, add methanol, stir, add 0.5% sodium hydroxide aqueous solution, stir, add dichloromethane for extraction, dry the dichloromethane organic phase with anhydrous magnesium sulfate, filter, distill the filtrate under reduced pressure, separate the mixture by silica gel column chromatography to obtain bisphenol functional monomer.

[0026] (3) Add 850 mmol bisphenol A, 150 mmol bisphenol functional monomer, 2.6 mol sodium hydroxide, 80 mmol triethylamine and 1.5 L water to the flask, stir and mix for 15 min, and control the stirring speed to 300 r / min; add 2.2 L of dichloromethane solution containing 400 mmol triphosgene dropwise, and control the dropwise addition time to 40 min. After the dropwise addition is completed, continue to stir the reaction at 30 °C for 20 min, add water to extract and remove the aqueous phase, add ethanol to the dichloromethane organic phase to precipitate, filter and wash the precipitate with ethanol and water, dry and obtain heat-resistant polycarbonate.

[0027] Example 4, a method for preparing heat-resistant polycarbonate: (1) Add 1.1 L tetrahydrofuran, 350 mmol bis(4-aminophenyl)acetylene, 700 mmol triethylamine and 840 mmol p-methoxybenzoyl chloride to a flask, heat to 65 °C, stir and reflux for 6 h, filter and distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain the precursor.

[0028] (2) Add 1.6 L of dichloromethane and 280 mmol of precursor to a flask, purge with nitrogen, and add 800 mL of dichloromethane solution containing 1.68 mol of boron tribromide dropwise in an ice-water bath. Stir the reaction at 25 °C for 8 h, add methanol, stir, add 0.5% sodium hydroxide aqueous solution, stir, add dichloromethane for extraction, dry the dichloromethane organic phase with anhydrous magnesium sulfate, filter, distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain bisphenol functional monomer.

[0029] (3) Add 800 mmol bisphenol A, 200 mmol bisphenol functional monomer, 2.4 mol sodium hydroxide, 80 mmol triethylamine and 1.5 L water to the flask, stir and mix for 20 min, and control the stirring speed to 500 r / min; add 2.1 L of dichloromethane solution containing 400 mmol triphosgene dropwise, and control the dropwise addition time to 30 min. After the dropwise addition is completed, continue to stir the reaction at 25 °C for 30 min, add water for extraction, remove the aqueous phase, add ethanol to the dichloromethane organic phase for precipitation, filter and wash the precipitate with ethanol and water, dry, and obtain heat-resistant polycarbonate.

[0030] Comparative Example 1: A method for preparing polycarbonate: (1) Add 1 mol bisphenol A, 2.3 mol sodium hydroxide, 70 mmol triethylamine and 1.3 L water to a flask, stir and mix for 20 min, and control the stirring speed at 500 r / min; add 2.2 L of dichloromethane solution containing 420 mmol triphosgene dropwise, and control the dropwise addition time at 30 min. After the dropwise addition is complete, continue stirring the reaction at 25 °C for 30 min, add water for extraction, remove the aqueous phase, add ethanol to the dichloromethane organic phase for precipitation, filter and wash the precipitate with ethanol and water, dry to obtain polycarbonate.

[0031] Comparative Example 2, a method for preparing polycarbonate: (1) Add 200 mL of tetrahydrofuran, 60 mmol of 4,4'-diaminodiphenylmethane, 120 mmol of triethylamine and 132 mmol of p-methoxybenzoyl chloride to a flask, heat to 65 °C, stir and reflux for 6 h, filter and distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain the precursor.

[0032] (2) Add 350 mL of dichloromethane and 50 mmol of precursor to a flask, purge with nitrogen, and in an ice-water bath, add 170 mL of dichloromethane solution containing 310 mmol of boron tribromide. Stir the reaction at 20 °C for 7 h, add methanol, stir, then add 0.5% sodium hydroxide aqueous solution, stir, and then add dichloromethane for extraction. Dry the dichloromethane organic phase with anhydrous magnesium sulfate, filter, and distill the filtrate under reduced pressure. Separate the mixture by silica gel column chromatography to obtain the bisphenol monomer, with the structural formula: .

[0033] (3) Add 970 mmol bisphenol A, 30 mmol bisphenol monomer, 2.3 mol sodium hydroxide, 70 mmol triethylamine and 1.3 L water to the flask, stir and mix for 20 min, and control the stirring speed at 500 r / min; add 2.2 L of dichloromethane solution containing 420 mmol triphosgene dropwise, and control the dropwise addition time at 30 min. After the dropwise addition is completed, continue to stir the reaction at 25 °C for 30 min, add water to extract and remove the aqueous phase, add ethanol to the dichloromethane organic phase to precipitate, filter and wash the precipitate with ethanol and water, dry to obtain polycarbonate.

[0034] Comparative Example 3, a method for preparing polycarbonate: The structural formula of bis(4,4'-dihydroxy)phenylacetylene is: It was prepared according to the method described in the literature Tetrahedron, 2011, vol. 67, # 42, p. 8177, "Calcium carbide as a cost-effective starting material for symmetrical diarylethynes via Pd-catalyzedcoupling reaction".

[0035] (1) Add 970 mmol bisphenol A, 30 mmol bis(4,4'-dihydroxy)phenylacetylene, 2.3 mol sodium hydroxide, 70 mmol triethylamine and 1.3 L water to a flask, stir and mix for 20 min, and control the stirring speed at 500 r / min; add 2.2 L of dichloromethane solution containing 420 mmol triphosgene dropwise, and control the dropwise addition time at 30 min. After the dropwise addition is completed, continue stirring the reaction at 25 °C for 30 min, add water for extraction, remove the aqueous phase, add ethanol to the dichloromethane organic phase for precipitation, filter and wash the precipitate with ethanol and water, dry to obtain polycarbonate.

[0036] Polycarbonate is melt-extruded in a twin-screw extruder at temperatures of 190℃, 240℃, 250℃, 260℃, 260℃, and 255℃, with a screw speed of 100 r / min. It is then pelletized in a pelletizer and injection molded in an injection molding machine at temperatures of 245℃, 260℃, and 260℃.

[0037] Weigh 8 mg of polycarbonate and place it in a thermogravimetric analyzer. Test its thermal properties in a nitrogen atmosphere. The heating rate is 5 °C / min, and the temperature range is 20-800 °C.

[0038] Table 1 Performance Tests

[0039] Compared to Comparative Example 1, the polycarbonates in each embodiment possess both high thermal decomposition temperature and high tensile strength, mainly because bisphenol functional monomers are added and copolymerized with bisphenol A, resulting in polycarbonate molecules with polyarylamide structural units in their main chain. ) and diphenylacetylene structure ( Polyarylamides have the characteristics of high modulus and high strength. At the same time, hydrogen bonds are formed between amide bonds, which enhances the interaction between molecular chains and is beneficial to improving tensile strength and mechanical properties. Furthermore, the introduced diphenylacetylene has high char-forming ability. At high temperatures, the acetylene group and aromatic ring are easily thermally crosslinked to form a fused ring structure, which significantly improves the heat resistance of polycarbonate and increases the thermal decomposition temperature.

[0040] The polycarbonate of Comparative Example 2 does not contain a diphenylacetylene structure, and its thermal decomposition temperature is lower than that of Example 1, resulting in poor heat resistance.

[0041] The polycarbonate of Comparative Example 3 does not contain polyarylamide structural units, and its tensile strength is significantly lower than that of Example 1.

Claims

1. A method for preparing heat-resistant polycarbonate, characterized in that, The preparation method includes: adding bisphenol A, bisphenol functional monomer, sodium hydroxide, triethylamine and water to a flask, stirring and mixing, adding a dichloromethane solution containing triphosgene dropwise and reacting, adding water for extraction, removing the aqueous phase, adding ethanol to the dichloromethane organic phase for precipitation, filtering and washing the precipitate, drying, and obtaining heat-resistant polycarbonate. The structural formula of the bisphenol functional monomer is as follows: .

2. The method for preparing heat-resistant polycarbonate according to claim 1, characterized in that, The molar ratio of bisphenol A, bisphenol functional monomer, sodium hydroxide, triethylamine, and triphosgene is (80-97):(3-20):(220-260):(7-10):(38-42).

3. The method for preparing heat-resistant polycarbonate according to claim 1, characterized in that, The time for adding the dichloromethane solution containing triphosgene is 30-40 minutes.

4. The method for preparing heat-resistant polycarbonate according to claim 1, characterized in that, The reaction temperature is 20-30℃ and the reaction time is 20-30 min.

5. The method for preparing heat-resistant polycarbonate according to claim 1, characterized in that, The stirring speed is 300-800 r / min.

6. The method for preparing heat-resistant polycarbonate according to claim 2, characterized in that, The preparation method of the bisphenol functional monomer is as follows: (1) Add tetrahydrofuran, bis(4-aminophenyl)acetylene, triethylamine, and p-methoxybenzoyl chloride in a molar ratio of 1:(2-2.1):(2-2.4) to a flask, react, filter, distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain the precursor; (2) Add dichloromethane and precursor to a flask, purge with nitrogen, and add a dichloromethane solution containing boron tribromide dropwise in an ice-water bath, controlling the molar ratio of precursor to boron tribromide to be 1:(5-6.2); react, add methanol after reaction, stir, add sodium hydroxide aqueous solution, stir, add dichloromethane for extraction, dry the dichloromethane organic phase with anhydrous magnesium sulfate, filter, distill the filtrate under reduced pressure, and separate the mixture by silica gel column chromatography to obtain bisphenol functional monomer.

7. The method for preparing heat-resistant polycarbonate according to claim 6, characterized in that, The reaction temperature in (1) is 60-70℃ and the reaction time is 4-6h.

8. The method for preparing heat-resistant polycarbonate according to claim 6, characterized in that, The reaction temperature in (2) is 20-30℃ and the reaction time is 5-8h.

9. A heat-resistant polycarbonate obtained by the preparation method according to any one of claims 1-8.

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