Efficient catalyst composition for preparing optical-grade PC and preparation method of PC

Abstract

The invention discloses a high-efficiency catalyst composition for preparing optical-grade PC (polycarbonate), the catalyst composition comprises a non-metal catalyst and a rare earth oxide, and the mass ratio of the non-metal catalyst to the rare earth oxide is 1: (0.1-1); the non-metal catalyst is prepared from at least one of N-heterocyclic carbene borate, 1, 5, 7-triazabicyclo [4.4. 0] dec-5-ene, N, N '-di-tert-butyltetramethylguanidine or 1, 3-di (2, 6-diisopropyl phenyl) imidazole-2-subunit, and the non-metal catalyst is prepared from at least one of N-heterocyclic carbene borate, 1, 5, 7-triazabicyclo [4.4. 0] dec-5-ene, N, N'-di-tert-butyltetramethylguanidine and 1, 3-di (2, 6 In the efficient catalyst for preparing the optical grade PC, the nonmetal catalyst has a high steric hindrance effect and can inhibit Fries side reaction, meanwhile, the rare earth oxide is introduced to serve as a cocatalyst, carbonyl is activated through Lewis acid, and the catalytic activity and catalytic efficiency are greatly improved.

Description

TECHNICAL FIELD

[0001] The embodiment of the application relates to the technical field of high polymer materials, and particularly relates to a high-efficiency catalyst combination for preparing optical-grade PC and a preparation method of PC. BACKGROUND

[0002] In recent years, with the rapid development of smart phones and new energy automobile industries, the demand for optical lens products is rapidly increasing. Polycarbonate (PC) is the first choice of materials for various optical lenses due to its good dimensional stability, high light transmittance, high refractive index and easy molding characteristics.

[0003] PC refers to a high polymer polymer with a carbonate group as a main chain. According to the molecular structure, polycarbonate can be divided into aliphatic, aromatic and aliphatic-aromatic polycarbonates. Among them, the melt transesterification method for preparing optical-grade PC is a solvent-free and environmentally friendly preparation process. The key is to realize high light transmittance, low color and narrow molecular weight distribution through high-efficiency catalyst and precise process control.

[0004] However, the existing melt transesterification method for preparing optical-grade PC mainly uses a single catalyst, such as alkali metal and alkaline earth metal. Such a single catalyst has low catalytic activity, and it is difficult to simultaneously realize high conversion rate and narrow molecular weight distribution. In addition, the single catalyst is prone to side reactions during the reaction process, resulting in high color and low light transmittance of the product. Moreover, the single catalyst has poor adaptability to reaction temperature and pressure, which limits the flexibility and stability of the process. Therefore, developing a composite catalyst system with high catalytic activity, good selectivity and wide process adaptability has become a key direction to improve the performance of the melt transesterification method for preparing optical-grade PC. SUMMARY

[0005] The application provides a high-efficiency catalyst combination for preparing optical-grade PC, which comprises a non-metallic catalyst and a rare earth oxide, wherein the mass ratio of the non-metallic catalyst to the rare earth oxide is 1:(0.1-1).

[0006] The non-metallic catalyst comprises at least one of N-heterocyclic carbene borate, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, N,N'-di-tert-butyltetramethylguanidine or 1,3-di(2,6-diisopropylphenyl)imidazol-2-ylidene.

[0007] The above non-metallic catalysts all have high steric hindrance effect, which can inhibit the occurrence of Fries side reaction. Meanwhile, the rare earth oxide is introduced as a cocatalyst to activate the carbonyl group through Lewis acid, thereby greatly improving the catalytic activity and efficiency.

[0008] Specifically, the rare earth oxide comprises at least one of lanthanum oxide, cerium oxide or yttrium oxide.

[0009] Preferably, the catalyst combination is N-heterocyclic carbene borate and lanthanum oxide, N-heterocyclic carbene borate and cerium oxide; wherein the mass ratio of N-heterocyclic carbene borate and lanthanum oxide is 1:(0.15-0.2), and the mass ratio of N-heterocyclic carbene borate and cerium oxide is 1:(0.2-0.5).

[0010] Specifically, the N-heterocyclic carbene borate [NHC] + [B(3,5-(CF3)2C6H3)4] is a high steric hindrance catalyst.

[0011] The application provides a preparation method of PC, comprising:

[0012] Under the protection of inert gas, bisphenol A, diphenyl carbonate and the catalyst combination according to any one of claims 1-4 are placed in a reaction kettle, the reaction temperature is 180-220 DEG C, the pressure is 80-120 mmHg, the reaction time is 2-8 h, and the ester exchange reaction is completed, wherein the mass ratio of bisphenol A, diphenyl carbonate and the catalyst combination is 1:(0.5-2):(0.01-0.3);

[0013] Slowly heat to 250-280 DEG C, and gradually reduce the pressure to less than 0.1 mmHg, and the condensation reaction is completed after at least 1 h;

[0014] 0.1-0.5wt% of an end-capping agent is added in the reaction kettle, and the terminal end-capping and devolatilization are completed to obtain the optical grade PC material.

[0015] The purity of bisphenol A (BPA) is greater than or equal to 99.95%, and the moisture content is less than 50 ppm, and the moisture content can be reduced to less than 10 ppm by vacuum drying. The purity of diphenyl carbonate (DPC) is greater than or equal to 99.9%, and the chloride ion content is less than 1 ppm to avoid catalyst poisoning.

[0016] Specifically, the mass ratio of bisphenol A, diphenyl carbonate and the catalyst combination is 1:(0.5-2):(0.01-0.3), and preferably 1:(0.8-1.5):(0.05-0.2).

[0017] In the ester exchange process, BPA and DPC undergo ester exchange in a molten state to generate oligomers and release phenol, in order to prevent PC from yellowing caused by Fries rearrangement, the reaction progress can be monitored by monitoring the phenol release rate, and the phenol released by the oligomers is condensed and recovered.

[0018] It should be noted that, in the ester exchange process, the preferred temperature is 190-220 DEG C, and the pressure is gradually reduced to 80-120 mmHg under normal pressure, and the preferred pressure is 90-100 mmHg.

[0019] During the polycondensation reaction, the temperature is raised in stages, i.e. the temperature is raised at a rate of 5-10℃ / 30min, preferably 8-10℃ / 30min, and preferably the heating temperature is 260-270℃, and the pressure is less than 0.05mmHg, i.e. the phenol can be removed under vacuum.

[0020] In order to increase the molecular weight, a rare earth oxide catalyst is added during the polycondensation reaction, and the mass ratio of the added rare earth oxide to the raw material in the reaction kettle is (0.001-0.1) : 1.

[0021] It should be noted that the end point of the polycondensation reaction can also be determined by determining the melt viscosity reaching the target value, which is usually η app >300Pa·s, at which time the molecular weight of the final polymer is Mw≈30,000-50,000g / mol, and by monitoring the stirring power, when the torque value is stable.

[0022] During the terminal end capping and devolatilization, the end capping agent is benzoate or p-tert-butyl benzoate. The devolatilization process is to remove the residual monomer and catalyst by using a thin film evaporator at a temperature of 250-270℃ and a pressure of <0.05mmHg, or to remove the gel particles by using a melt filter.

[0023] The high-efficiency catalyst used in the preparation of optical-grade PC has high steric hindrance effect, which can inhibit the occurrence of Fries side reaction, and the rare earth oxide is introduced as a cocatalyst to activate the carbonyl group by using Lewis acid, which greatly improves the catalytic activity and catalytic efficiency. DETAILED DESCRIPTION

[0024] Comparative Example 1

[0025] 1. Under the protection of inert argon gas, bisphenol A and diphenyl carbonate are placed in the reaction kettle at a ratio of 1:1, the reaction temperature is 220℃, the pressure is 100mmHg, and the reaction time is 5h, and an ester exchange reaction is carried out;

[0026] 2. Slowly raise the temperature to 280℃, gradually reduce the pressure to less than 0.1mmHg, and react for 1h to complete the polycondensation reaction;

[0027] 3. Add 0.3wt% of the end capping agent benzoate to the reaction kettle, and remove the residual monomer and catalyst by using a thin film evaporator at a temperature of 270℃ and a pressure of 0.03mmHg to complete the terminal end capping and devolatilization.

[0028] Comparative Example 2

[0029] 1. Under the protection of inert gas argon, bisphenol A, diphenyl carbonate and N-heterocyclic carbene borate were placed in a reaction kettle according to 1:1:0.1, the reaction temperature was 220℃, the pressure was 100mmHg, and the reaction time was 5h, to perform ester exchange reaction;

[0030] 2. Slowly heated to 280℃, gradually reduced the pressure to less than 0.1mmHg, reacted for 1h, to complete the polycondensation reaction;

[0031] 3. 0.3wt% of end-capping agent benzoate was added in the reaction kettle, and thin film evaporator was used to remove residual monomer and catalyst at a temperature of 270℃ and a pressure of 0.03mmHg, to complete the terminal end-capping and devolatilization.

[0032] Comparative Example 3

[0033] 1. Under the protection of inert gas argon, bisphenol A, diphenyl carbonate and lanthanum oxide were placed in a reaction kettle according to 1:1:0.1, the reaction temperature was 220℃, the pressure was 100mmHg, and the reaction time was 5h, to perform ester exchange reaction;

[0034] 2. Slowly heated to 280℃, gradually reduced the pressure to less than 0.1mmHg, reacted for 1h, to complete the polycondensation reaction;

[0035] 3. 0.3wt% of end-capping agent benzoate was added in the reaction kettle, and thin film evaporator was used to remove residual monomer and catalyst at a temperature of 270℃ and a pressure of 0.03mmHg, to complete the terminal end-capping and devolatilization.

[0036] Example 1

[0037] 1. Under the protection of inert gas argon, bisphenol A, diphenyl carbonate and catalyst combination were placed in a reaction kettle according to the component ratio shown in Table 1, the reaction temperature was 220℃, the pressure was 100mmHg, and the reaction time was 5h, to perform ester exchange reaction;

[0038] 2. Slowly heated to 280℃, gradually reduced the pressure to less than 0.1mmHg, reacted for 1h, to complete the polycondensation reaction;

[0039] 3. 0.3wt% of end-capping agent benzoate was added in the reaction kettle, and thin film evaporator was used to remove residual monomer and catalyst at a temperature of 270℃ and a pressure of 0.03mmHg, to complete the terminal end-capping and devolatilization.

[0040] Example 2

[0041] 1. Under the protection of inert gas argon, bisphenol A, diphenyl carbonate and catalyst combination were placed in a reaction kettle according to the component ratio shown in Table 1, the reaction temperature was 220℃, the pressure was 100mmHg, and the reaction time was 5h, to perform ester exchange reaction;

[0042] 2. Slowly increase the temperature to 280°C, gradually reduce the pressure to less than 0.1 mmHg, and react for 1 h to complete the polycondensation reaction. Add 0.1 parts by mass of lanthanum oxide as a rare earth oxide to the reaction;

[0043] 3. Add 0.3 wt% of a capping agent, benzoate, to the reaction kettle, and remove the residual monomer and catalyst at a temperature of 270°C and a pressure of 0.03 mmHg using a thin film evaporator to complete the terminal capping and devolatilization.

[0044] The implementation process of Examples 3-9 is similar to that of Example 2, and will not be described here again.

[0045] Table 1. Catalyst combination (parts by mass)

[0046] Example Non-metallic catalyst Rare earth oxide Example 1 N-heterocyclic carbene borate: 1 Lanthanum oxide: 0.2 Example 2 N-heterocyclic carbene borate: 1 Lanthanum oxide: 0.2 Example 3 N-heterocyclic carbene borate: 1 Cerium oxide: 0.2 Example 4 N-heterocyclic carbene borate: 1 Yttrium oxide: 0.2 Example 5 N-heterocyclic carbene borate: 1 Lanthanum oxide: 0.15 Example 6 N-heterocyclic carbene borate: 1 Lanthanum oxide: 0.3 Example 7 1,5,7-triazabicyclo[4.4.0]dec-5-ene: 1 Lanthanum oxide: 0.2 Example 8 N,N'-di-tert-butyltetramethylguanidine: 1 Lanthanum oxide: 0.2 Example 9 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylidene: 1 Lanthanum oxide: 0.2

[0047] The PC materials prepared in Comparative Examples 1-3 and Examples 1-9 were tested for light transmittance (reference: ISO 13468-2), haze (reference: ISO 14782), density (reference: ISO 1183-1), Izod notched impact strength (reference: ISO 180 / A (23°C / -30°C)), water absorption (reference: ISO 62), Vicat softening point (reference: ISO 306), tensile strength (reference: ISO 527-1), tensile elongation at break (reference: ISO 527-1), and yellowness index (reference: ASTM E303).

[0048] The detection equipment information is as follows:

[0049] Light transmittance tester: SGW-820, using parallel illumination and hemispherical scattering principle, supporting A / C two light sources (2856K / 6447K);

[0050] Haze detector: Linshang LS155B;

[0051] Solid density detector: XF-300S;

[0052] Simply supported beam / cantilever beam impact testing machine: JB-300B;

[0053] Water absorption detection equipment: YQK-200, Beijing Zhonghuitiancheng Technology;

[0054] Vicat softening point testing equipment: XRW-300A;

[0055] Tensile strength tester: HD-B609B-S;

[0056] SC-T45 yellowness index meter: SUGA (Japan).

[0057] Table 2. Test results 1

[0058]

[0059]

[0060] The experimental data of the PC materials prepared by the above comparative examples and examples show that the detection data of the examples are improved relative to the comparative examples, indicating that the catalyst combination significantly improves the performance of the PC material relative to the single catalyst.

[0061] Example 2 supplements rare earth oxide in the polycondensation reaction stage relative to Example 1, and the performance of Example 2 is better than that of Example 1.

[0062] As can be seen from Examples 2 and 3 and Example 4, the catalyst combination of N-heterocyclic carbene borate and lanthanum oxide and cerium oxide is better than the combination with yttrium oxide.

[0063] As can be seen from Example 2 and Examples 7-9, the catalyst combination of N-heterocyclic carbene borate and lanthanum oxide is significantly better than the catalyst combination of 1,5,7-triazabicyclo[4.4.0]dec-5-ene, N,N'-di-tert-butyltetramethylguanidine and 1,3-di(2,6-diisopropylphenyl)imidazol-2-ylidene and lanthanum oxide.

[0064] The above examples are merely examples for the purpose of clarity and do not limit the embodiments. Based on the above description, other different forms of changes or variations can be made by those of ordinary skill in the art. All embodiments do not need to be exhaustively listed here. The obvious changes or variations derived therefrom are still within the protection scope of the present application.

[0065] The above is only part of the embodiments of the present application, and it should be pointed out that for those of ordinary skill in the art, without departing from the principles of the present application, a number of improvements and refinements can be made, and these improvements and refinements should be considered as the protection scope of the present application.

Claims

1. A highly efficient catalyst combination for preparing optical-grade PC, characterized in that, The catalyst combination comprises: a non-metallic catalyst and rare earth oxides, wherein the mass ratio of the non-metallic catalyst to the rare earth oxides is 1:(0.1-1); The non-metallic catalyst includes at least one of N-heterocyclic carbene borate, 1,5,7-triazabicyclo[4.4.0]dec-5-ene, N,N'-di-tert-butyltetramethylguanidine, or 1,3-bis(2,6-diisopropylphenyl)imidazol-2-ylene.

2. The catalyst combination according to claim 1, characterized in that, Rare earth oxides include at least one of lanthanum oxide, cerium oxide, or yttrium oxide.

3. The catalyst combination according to claim 2, characterized in that, The catalyst combination consists of N-heterocyclic carbene borate and lanthanum oxide, and N-heterocyclic carbene borate and cerium oxide.

4. The catalyst combination according to claim 3, characterized in that, The mass ratio of N-heterocyclic carbene borate to lanthanum oxide is 1:(0.15-0.2), and the mass ratio of N-heterocyclic carbene borate to cerium oxide is 1:(0.2-0.5).

5. A method for preparing PC, characterized in that, include: Under inert gas protection, bisphenol A, diphenyl carbonate, and the catalyst combination according to any one of claims 1-4 are placed in a reaction vessel. The reaction temperature is 180-220℃, the pressure is 80-120 mmHg, and the reaction time is 2-8 h to complete the transesterification reaction. The mass ratio of bisphenol A, diphenyl carbonate, and the catalyst combination is 1:(0.05-2):(0.01-0.3). Slowly raise the temperature to 250-280℃ and gradually reduce the pressure to below 0.1 mmHg, allowing the reaction to proceed for at least 1 hour to complete the polycondensation reaction. Add 0.1-0.5 wt% of end-capping agent to the reactor to complete the terminal capping and devolatilization to obtain optical grade PC material.

6. The preparation method according to claim 5, characterized in that, Also includes: Rare earth oxides are added as catalysts in the polycondensation reaction. The mass ratio of the added rare earth oxides to the raw materials in the reactor is (0.001-0.1):

1.

7. The preparation method according to claim 5, characterized in that, The capping agent is at least one of benzoate or p-tert-butylbenzoate.

8. The preparation method according to claim 5, characterized in that, The devolatilization process is as follows: Residual monomers and catalysts can be removed using a thin-film evaporator at a temperature of 250-270℃ and a pressure of <0.05mmHg, or gel particles can be retained using a melt filter.

9. The preparation method according to claim 5, characterized in that, The mass ratio of bisphenol A, diphenyl carbonate and catalyst is 1:(0.8-1.5):(0.05-0.2).

10. The preparation method according to claim 5, characterized in that, Also includes: In the transesterification reaction, the phenol released from the oligomers is recovered by condensation.

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