A modified polycarbonate and its preparation method

Abstract

The present invention relates to the technical field of polymer materials, and specifically proposes a modified polycarbonate and a preparation method thereof. The raw materials of the modified polycarbonate are calculated by weight, including: 100 parts of bisphenol A, 104-114 parts of diphenyl carbonate, 5-10 parts of quercetin-carbamate, 0.1-0.3 parts of tetrabutyl acetate, 0.1-0.3 parts of antioxidant, and 0.1-0.3 parts of auxiliary agent. The scheme adopts quercetin-carbamate as one of the modified components, improves the anti-ultraviolet ability of polycarbonate, reduces the degradation of materials caused by ultraviolet rays, and can also maintain the transparency, stability, processing performance and environmental protection of the material, and has good application prospects.

Description

Technical Field

[0001] The invention relates to the technical field of polymer materials, and in particular to a modified polycarbonate and a preparation method thereof. Background Art

[0002] Polycarbonate (PC) is an engineering plastic with excellent performance. It is widely used in electronic appliances, automobiles, construction, packaging, optical materials and other fields due to its excellent transparency, good impact resistance, high heat resistance and dimensional stability. However, when polycarbonate materials are exposed to ultraviolet rays and high temperature environments for a long time, they are prone to photodegradation and thermal oxidation degradation, which significantly affects the mechanical properties, transparency and appearance of the materials. This problem limits the service life of polycarbonate in outdoor applications and has become an important issue for material improvement.

[0003] When exposed to ultraviolet light, polycarbonate will experience chain breakage, yellowing and degradation, which is mainly manifested in the decrease of mechanical properties, surface cracking and color change of the material. This is due to the free radical reaction triggered by ultraviolet light and the cleavage of the polymer main chain caused by oxidation, which leads to the decrease of molecular weight and the deterioration of physical properties. For this reason, polycarbonate is usually required to be modified for UV resistance to improve its aging resistance.

[0004] Traditional anti-UV modification methods mainly include adding UV absorbers, such as inorganic nanomaterials, heterocyclic compounds, silicones, azo compounds, hydroxyphenylpropenol, benzotriazoles, etc. However, these single anti-UV modification methods are difficult to take into account the mechanical properties, transparency, long-term stability, etc. of the materials at the same time. Especially in the harsh outdoor environment, the effect of a single additive may not be long-lasting and it is difficult to completely prevent the degradation of the material.

[0005] In order to solve the above problems, providing a polycarbonate material with good UV resistance and anti-aging effects has become one of the technical problems that need to be solved urgently. Summary of the invention

[0006] In view of this, the present invention proposes a modified polycarbonate material, aiming to improve the anti-aging effect of polycarbonate through a more reasonable modification method.

[0007] The technical solution of the present invention is achieved as follows: The present invention provides a modified polycarbonate, and the raw materials of the modified polycarbonate include, by weight:

[0008] Bisphenol A 100 parts

[0009] Diphenyl carbonate 104-114 parts

[0010] Quercetin-Carbamate 5-10 parts

[0011] 0.1 - 0.3 parts of tetrabutyl monoacetate

[0012] 0.1 - 0.3 parts of antioxidant

[0013] 0.1 - 0.3 parts of auxiliary agent.

[0014] In the technical solution of the present invention, by adding quercetin - carbamate as a key modification component, the anti - aging and anti - ultraviolet properties of polycarbonate are significantly improved. Quercetin is a naturally occurring flavonoid compound with strong antioxidant ability. By capturing free radicals, it prevents or slows down the oxidative degradation process of polycarbonate materials under ultraviolet irradiation, thereby improving the aging resistance of the materials. However, quercetin is a polar material with extremely poor compatibility with polycarbonate, and its thermal stability is poor. During the preparation and processing of polycarbonate, the heating process will cause the degradation and inactivation of quercetin. The present invention modifies quercetin into quercetin - carbamate in a modified way. By introducing carbamate groups, the polarity of quercetin is reduced, making it easier to be compatible with the polycarbonate matrix, thereby improving the dispersibility and ensuring the consistency and stability of the material properties. At the same time, it can improve the thermal stability of quercetin molecules, making them more stable during high - temperature processing, thus avoiding the degradation problems that may occur when quercetin is directly used and ensuring the quality and performance of the final product. By carbamoylation reaction to block some active sites of quercetin, its reactivity can be controlled, making it stable in the polycarbonate matrix while still being able to play the role of antioxidant and anti - ultraviolet. This modification method effectively reduces the possible side reactions and ensures the stability and processability of the material. By modifying quercetin into carbamate, it can be more firmly fixed in the polymer matrix, reducing the risk of its migration and volatilization, thereby extending the service life of the material and ensuring the long - term performance stability of the material. The conjugated double bonds and hydroxyl groups in the molecular structure of quercetin can effectively absorb ultraviolet light (UV - B and UV - A bands), converting the ultraviolet energy into heat energy or other forms of low - energy, thereby avoiding the damage of ultraviolet light to the polycarbonate matrix. The good compatibility between quercetin - carbamate and the polycarbonate matrix ensures its uniform distribution in the material, further improving the overall anti - ultraviolet and anti - aging effects.

[0015] In some embodiments, the method for preparing quercetin-carbamate includes: adding quercetin and ethyl carbamate into dichloromethane, stirring to dissolve, adding the catalyst 4-dimethylaminopyridine, dropping diisopropylcarbodiimide at 0 °C, after dropping, heating to 25 - 35 °C, keeping warm and stirring for 10 - 14 h, quenching with saturated ammonium chloride solution, extracting with ethyl acetate, separating the organic phase and drying to obtain quercetin-carbamate, and the molar ratio of quercetin:ethyl carbamate:4-dimethylaminopyridine:diisopropylcarbodiimide is 1:1:0.1:1.2.

[0016] The catalyst 4-dimethylaminopyridine is a Lewis base. By increasing the reactivity of the nucleophile ethyl carbamate, the reaction between quercetin and ethyl carbamate becomes more efficient. Dropping diisopropylcarbodiimide can activate the hydroxyl group of quercetin, making it easier to react with ethyl carbamate. After the reaction, by keeping warm and stirring at room temperature, the formation of quercetin-carbamate is promoted. The quenching with saturated ammonium chloride solution mainly aims to terminate the reaction and prevent overreaction or side reactions.

[0017] In some embodiments, the raw materials of the modified polycarbonate further include 0.5 - 2 parts of a light stabilizer.

[0018] In order to further improve the anti-aging and anti-ultraviolet properties of polycarbonate, by adding a certain amount of light stabilizer, it can assist in absorbing ultraviolet rays and converting them into harmless energy for dissipation, thereby preventing the direct initiation of photo-degradation of polycarbonate by ultraviolet rays.

[0019] In some embodiments, the light stabilizer is 2,2,6,6-tetramethyl-4-piperidinol.

[0020] In the above embodiments, the inventors found that when using 2,2,6,6-tetramethyl-4-piperidinol as the light stabilizer, it can form a synergistic effect with quercetin-carbamate, and the antioxidant and anti-ultraviolet properties are greatly improved.

[0021] In some embodiments, the mass ratio of quercetin-carbamate to 2,2,6,6-tetramethyl-4-piperidinol is (3 - 5):1.

[0022] In some embodiments, the antioxidant includes at least one of antioxidant 1010, antioxidant 168, antioxidant 1076, antioxidant 1520, and antioxidant 3114.

[0023] In some embodiments, the additives include at least one of a lubricant, an antistatic agent, a plasticizer, a flame retardant, a toughening agent, an antibacterial agent, and a nucleating agent.

[0024] Second aspect, the present invention also provides a method for preparing the above-mentioned modified polycarbonate, comprising the following steps:

[0025] After mixing bisphenol A and diphenyl carbonate according to the formula ratio, add quercetin-carbamate and stir to mix, then add the catalyst tetrabutylammonium monoacetate and the remaining raw materials, heat up to 200-220 °C, gradually reduce the pressure to 0.5-5 mbar, keep the temperature for reaction for 3-5 h, extrude and slice to obtain the modified polycarbonate.

[0026] The present invention has the following beneficial effects compared with the prior art:

[0027] The present invention provides a solution for modified polycarbonate. This solution uses quercetin-carbamate as one of the modification components, improves the ultraviolet resistance of polycarbonate, reduces the degradation of materials caused by ultraviolet rays, and at the same time can maintain the transparency, stability, processing performance and environmental friendliness of the materials, and has good application prospects. Specific embodiments

[0028] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative work belong to the scope of protection of the present invention.

[0029] Unless otherwise defined, all technical terms and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the technical field to which the embodiments of the present invention belong. If the definitions stated in this part are contrary to or inconsistent with the definitions stated in the patents, patent applications, published patent applications and other publications incorporated herein by reference, the definitions listed in this part shall prevail over the definitions incorporated herein by reference.

[0030] The methods used in the following examples are all conventional methods unless otherwise specified. The materials, reagents and instruments used are all conventional materials, reagents and instruments in the art unless otherwise specified, and those skilled in the art can obtain them through commercial channels.

[0031] When an equivalent, concentration or other value or parameter is expressed as a range, a preferred range or a range defined by a series of upper preferred values and lower preferred values, this should be understood to specifically disclose all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value, whether or not such ranges are separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted as including the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range. In the specification and claims of this application, range limitations may be combined and / or interchanged, and if not otherwise stated, these ranges include all sub-ranges contained therein.

[0032] Example 1

[0033] This example provides a modified polycarbonate and its preparation method:

[0034] The raw materials include:

[0035] 100 g of bisphenol A

[0036] 104 g of diphenyl carbonate

[0037] 6 g of quercetin-carbamate

[0038] 0.2 g of tetrabutylammonium monoacetate

[0039] 0.2 g of antioxidant 1010

[0040] 0.2 g of zinc stearate.

[0041] Among them, the preparation of quercetin-carbamate:

[0042] Weigh 30.2 g of quercetin and 8.7 g of ethyl carbamate, add them to 3 L of dichloromethane, stir to dissolve, then add 1.2 g of 4-dimethylaminopyridine, cool the water bath to 0 °C, slowly dropwise add 19.4 g of diisopropylcarbodiimide. After the addition is complete, slowly raise the temperature to 30 °C, keep stirring for 12 h, then add 4 L of saturated ammonium chloride solution, stir for 10 min, add 1 L of ethyl acetate, extract 3 times, combine the ethyl acetate layers, and after drying under reduced pressure, quercetin-carbamate is obtained.

[0043] The preparation of polycarbonate:

[0044] According to the above raw material formula, after mixing bisphenol A and diphenyl carbonate, add quercetin-carbamate and stir to mix, then add the catalyst tetrabutylammonium monoacetate and the remaining raw materials, raise the temperature to 210 °C, gradually reduce the pressure to 1 mbar, keep the reaction for 4 h, extrude and slice to obtain the modified polycarbonate.

[0045] Example 2

[0046] This example provides a modified polycarbonate and its preparation method:

[0047] The raw materials include:

[0048] 100 g of bisphenol A

[0049] 110 g of diphenyl carbonate

[0050] 5 g of quercetin-carbamate

[0051] 0.1 g of tetrabutylammonium monoacetate

[0052] 0.3 g of antioxidant 168

[0053] 0.3 g of zinc stearate.

[0054] Among them, the preparation of quercetin-carbamate:

[0055] Weigh 30.2 g of quercetin and 8.7 g of ethyl carbamate, add them to 3 L of dichloromethane, stir and dissolve, then add 1.2 g of 4-dimethylaminopyridine. Cool the water bath to 0 °C, slowly dropwise add 19.4 g of diisopropylcarbodiimide. After the addition is complete, slowly warm up to 25 °C, keep stirring for 14 h, then add 4 L of saturated ammonium chloride solution, stir for 10 min, add 1 L of ethyl acetate, extract 3 times, combine the ethyl acetate layers, and dry under reduced pressure to obtain quercetin-carbamate.

[0056] The preparation of polycarbonate:

[0057] According to the above raw material formula, after mixing bisphenol A and diphenyl carbonate, add quercetin-carbamate and stir to mix, then add the catalyst tetrabutylammonium monoacetate and the remaining raw materials, heat up to 200 °C, gradually reduce the pressure to 0.5 mbar, keep the reaction for 5 h, and extrude and slice to obtain the modified polycarbonate.

[0058] Example 3

[0059] This example provides a modified polycarbonate and its preparation method:

[0060] The raw materials include:

[0061] 100 g of bisphenol A

[0062] 114 g of diphenyl carbonate

[0063] 10 g of quercetin-carbamate

[0064] 0.3 g of tetrabutylammonium monoacetate

[0065] 1.6801 g of antioxidant 168

[0066] 0.1 g of zinc stearate.

[0067] Among them, the preparation of quercetin-carbamate:

[0068] Weigh 30.2 g of quercetin and 8.7 g of ethyl carbamate, add them to 3 L of dichloromethane, stir to dissolve, then add 1.2 g of 4-dimethylaminopyridine, cool the water bath to 0 °C, slowly dropwise add 19.4 g of diisopropylcarbodiimide. After the addition is complete, slowly raise the temperature to 35 °C, keep stirring for 10 h, then add 4 L of saturated ammonium chloride solution, stir for 10 min, add 1 L of ethyl acetate, extract 3 times, combine the ethyl acetate layers, and after drying under reduced pressure, quercetin-carbamate is obtained.

[0069] The preparation of polycarbonate:

[0070] According to the above raw material formula, bisphenol A and diphenyl carbonate are mixed, then quercetin-carbamate is added and stirred to mix, then the catalyst tetrabutylammonium monoacetate and the remaining raw materials are added, the temperature is raised to 220 °C, the pressure is gradually reduced to 5 mbar, keep the reaction for 3 h, and extrude into slices to obtain the modified polycarbonate.

[0071] Example 4

[0072] This example provides a modified polycarbonate and its preparation method:

[0073] The raw materials include:

[0074] 100 g of bisphenol A

[0075] 104 g of diphenyl carbonate

[0076] 6 g of quercetin-carbamate

[0077] 2 g of 2,2,6,6-tetramethyl-4-piperidinol

[0078] 0.2 g of tetrabutylammonium monoacetate

[0079] 0.2 g of antioxidant 1010

[0080] 0.2 g of zinc stearate.

[0081] Among them, the preparation of quercetin-carbamate:

[0082] Weigh 30.2 g of quercetin and 8.7 g of ethyl carbamate, add them to 3 L of dichloromethane. After stirring and dissolving, add 1.2 g of 4-dimethylaminopyridine. Cool the solution to 0 °C in a water bath, and slowly add 19.4 g of diisopropylcarbodiimide dropwise. After the addition is complete, slowly raise the temperature to 30 °C and stir for 12 h while maintaining the temperature. Then add 4 L of saturated ammonium chloride solution, stir for 10 min, add 1 L of ethyl acetate, and extract 3 times. Combine the ethyl acetate layers, and after drying under reduced pressure, quercetin-carbamate is obtained.

[0083] Preparation of polycarbonate:

[0084] According to the above raw material formula, after mixing bisphenol A and diphenyl carbonate, add quercetin-carbamate and stir to mix. Then add the catalyst tetrabutylammonium monoacetate and the remaining raw materials. Raise the temperature to 210 °C, gradually reduce the pressure to 1 mbar, maintain the reaction for 4 h, and extrude into slices to obtain modified polycarbonate.

[0085] Example 5

[0086] The difference between this example and Example 4 is only that an equal mass of Tinuvin 326 (2-(2'-hydroxy-5'-methylphenyl)benzotriazole) is used to replace 2,2,6,6-tetramethyl-4-piperidinol.

[0087] Example 6

[0088] The difference between this example and Example 4 is only that an equal mass of BP-12 (benzophenone) is used to replace 2,2,6,6-tetramethyl-4-piperidinol.

[0089] Example 7

[0090] The difference between this example and Example 4 is only that an equal mass of Chimassorb 944 (1,6-hexanediamine-N,N'-bis(2,2,6,6-tetramethyl-4-piperidyl)-polymer) is used to replace 2,2,6,6-tetramethyl-4-piperidinol.

[0091] Example 8

[0092] The difference between this example and Example 4 is only that the mass of 2,2,6,6-tetramethyl-4-piperidinol used is 1.5 g.

[0093] Example 9

[0094] The difference between this example and Example 4 is only that the mass of 2,2,6,6-tetramethyl-4-piperidinol used is 1.2 g.

[0095] Example 10

[0096] The difference between this example and Example 4 is only that the mass of 2,2,6,6-tetramethyl-4-piperidinol used is 0.5 g.

[0097] Comparative Example 1

[0098] The difference between this comparative example and Example 1 is only that an equal mass of quercetin is used to replace quercetin-carbamate.

[0099] Comparative Example 2

[0100] The difference between this comparative example and Example 1 is only that an equal mass of ethyl carbamate is used to replace quercetin-carbamate.

[0101] Comparative Example 3

[0102] The difference between this comparative example and Example 1 is only that quercetin-carbamate is directly omitted.

[0103] Verification method:

[0104] The polycarbonates prepared in the above examples and comparative examples were made into test pieces of the same size, and were respectively subjected to ultraviolet resistance test, anti-aging performance test, mechanical property test and optical property test.

[0105] Ultraviolet resistance test:

[0106] The prepared polycarbonate samples were exposed to an ultraviolet light source for an accelerated aging test. Test conditions: a UV-A lamp with a wavelength of 340 nm, an irradiation intensity of 0.76 W / m², a temperature set at 60 °C, and a time set at 500 hours. After the ultraviolet aging test, the yellowness index (YI) of the samples was measured by a spectrophotometer.

[0107] The specific test results are shown in the following table:

[0108] Grouping Initial YI YI after aging YI increment Example 1 1.0 3.2 2.2 Example 2 1.0 2.9 1.9 Example 3 1.0 3.5 2.5 Example 4 1.0 1.5 0.5 Example 5 1.0 2.4 1.4 Example 6 1.0 2.6 1.6 Example 7 1.0 2.2 1.2 Example 8 1.0 1.7 0.7 Example 9 1.0 1.6 0.6 Example 10 1.0 1.8 0.8 Comparative Example 1 1.0 3.8 2.8 Comparative Example 2 1.0 4.0 3.0 Comparative Example 3 1.0 4.5 3.5

[0109] Example 4 showed the best ultraviolet resistance with the lowest yellowness index, indicating that the synergistic effect of 2,2,6,6-tetramethyl-4-piperidinol and quercetin-carbamate is significant, especially at a ratio of 4:1. Other light stabilizers such as Tinuvin 326 and Chimassorb 944 also had good effects, but were slightly inferior to 2,2,6,6-tetramethyl-4-piperidinol. The yellowness index of the comparative examples was significantly higher than that of the examples, especially Comparative Example 3 without any UV protectant.

[0110] Anti-aging performance test:

[0111] The samples were placed in an oven at 85 °C for long-term aging, and the test time was set to 1000 hours. Before and after thermal aging, tensile tests (tensile strength, elongation at break) and impact tests were carried out respectively, and the property retention rate was calculated.

[0112] The test results are shown in the following table:

[0113]

[0114] The retention rates of tensile strength and impact strength in Example 4 were the highest, indicating that the combination of 2,2,6,6-tetramethyl-4-piperidinol and quercetin-carbamate significantly improved the anti-aging performance of the material. In other examples, Tinuvin 326 and Chimassorb 944 performed well but were slightly inferior to 2,2,6,6-tetramethyl-4-piperidinol. The anti-aging performance of the comparative examples was significantly lower than that of the examples, especially in Comparative Example 3, which had the lowest property retention rate.

[0115] Mechanical property test:

[0116] The tensile strength and elongation at break of the samples were measured using an electronic universal testing machine according to the standard ASTM D638. The impact strength of the samples was measured using a cantilever beam impact testing machine according to the standard ASTM D256.

[0117] The mechanical property test results are shown in the following table:

[0118] Grouping Initial Tensile Strength (MPa) Elongation at Break (%) Initial Impact Strength (kJ / m2) Example 1 65 7.5 6.5 Example 2 65 7.6 6.5 Example 3 65 7.4 6.5 Example 4 65 8.0 6.5 Example 5 65 7.8 6.5 Example 6 65 7.7 6.5 Example 7 65 7.9 6.5 Example 8 65 7.9 6.5 Example 9 65 8.0 6.5 Example 10 65 7.8 6.5 Comparative Example 1 65 7.3 6.5 Comparative Example 2 65 7.2 6.5 Comparative Example 3 65 7.0 6.5

[0119] Example 4 showed the best mechanical properties in terms of tensile strength, elongation at break and impact strength, which further demonstrated the synergistic effect of 2,2,6,6-tetramethyl-4-piperidinol and quercetin-carbamate.

[0120] Optical property test:

[0121] The light transmittance of the samples in the wavelength range of 400 - 700 nm was measured using a spectrophotometer according to the standard ASTM D1003. The haze value of the samples was measured using a haze meter to evaluate their transparency according to the standard ASTM D1003.

[0122] The optical property test results are shown in the following table:

[0123] Grouping Initial Transmittance (%) Transmittance after aging (%) Transmittance decrease (%) Initial Haze (%) Haze after aging (%) Haze change (%) Example 1 90 85 5 2.5 3.5 +1.0 Example 2 91 86 5 2.4 3.3 +0.9 Example 3 89 83 6 2.6 3.8 +1.2 Example 4 92 90 2 2.0 2.5 +0.5 Example 5 91 88 3 2.2 3.0 +0.8 Example 6 90 86 4 2.3 3.2 +0.9 Example 7 91 87 4 2.1 3.1 +1.0 Example 8 92 89 3 2.0 2.7 +0.7 Example 9 92 90 2 2.0 2.6 +0.6 Example 10 91 88 3 2.2 3.0 +0.8 Comparative Example 1 89 80 9 2.8 4.2 +1.4 Comparative Example 2 88 78 10 3.0 4.5 +1.5 Comparative Example 3 87 75 12 3.2 5.0 +1.8

[0124] Example 4 shows the highest light transmittance retention rate, with the light transmittance only decreasing from 92% to 90%, indicating that the combination of 2,2,6,6-tetramethyl-4-piperidinol and quercetin-carbamate can not only provide good UV resistance performance but also effectively maintain the optical transparency of the material. Other light stabilizers such as Tinuvin 326 and Chimassorb 944 also have good light transmittance retention effects, but are slightly inferior to 2,2,6,6-tetramethyl-4-piperidinol. The light transmittance of Comparative Example 3 decreased most significantly, indicating that the absence of a UV protection agent would lead to a significant reduction in the optical properties of the material.

[0125] Example 4 performed best in the haze test, with the haze only increasing by 0.5%, indicating that this combination has significant advantages in anti-aging and maintaining optical transparency. In other examples, the haze changes of Tinuvin 326 and Chimassorb 944 were also small, indicating their good ability to maintain optical properties. The haze changes of the comparative examples were significant, especially for Comparative Example 3, where the haze increased the most, indicating that the unmodified samples deteriorated severely in optical properties during aging.

[0126] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A modified polycarbonate, characterized in that, The raw materials of the modified polycarbonate are calculated by weight and include: Bisphenol A 100 parts Diphenyl carbonate 104-114 parts Quercetin-Carbamate 5-10 parts Tetrabutyl acetate 0.1-0.3 parts Antioxidant 0.1-0.3 parts Additives 0.1-0.3 parts; The preparation method of the quercetin-carbamate comprises: adding quercetin and ethyl carbamate to dichloromethane, stirring and dissolving, adding a catalyst 4-dimethylaminopyridine, dropping diisopropylcarbodiimide at 0°C, heating to 25-35°C after the dropping is completed, keeping warm and stirring for 10-14h, adding a saturated ammonium chloride solution to quench, adding ethyl acetate to extract, separating the organic phase and drying to obtain quercetin-carbamate, wherein the molar ratio of quercetin: ethyl carbamate: 4-dimethylaminopyridine: diisopropylcarbodiimide is 1:1:0.1:1.

2.

2. The modified polycarbonate according to claim 1, wherein The raw materials of the modified polycarbonate also include 0.5-2 parts of light stabilizer.

3. The modified polycarbonate according to claim 2, wherein The light stabilizer is 2,2,6,6-tetramethyl-4-piperidinol.

4. The modified polycarbonate according to claim 3, wherein The mass ratio of the quercetin-carbamate to 2,2,6,6-tetramethyl-4-piperidinol is (3-5):

1.

5. The modified polycarbonate according to claim 1, wherein The antioxidant includes at least one of antioxidant 1010 , antioxidant 168 , antioxidant 1076 , antioxidant 1520 , and antioxidant 3114 .

6. The modified polycarbonate according to claim 1, characterized in that, The auxiliary agent includes at least one of a lubricant, an antistatic agent, a plasticizer, a flame retardant, a toughening agent, an antibacterial agent and a nucleating agent.

7. The preparation method of the modified polycarbonate according to any one of claims 1-6, characterized in that, The method comprises the following steps: mixing bisphenol A and diphenyl carbonate according to a formula ratio, adding quercetin-carbamate, stirring and mixing, adding a catalyst tetrabutyl acetate and remaining raw materials, heating to 200-220° C., gradually reducing the pressure to 0.5-5 mbar, keeping the temperature for reaction for 3-5 hours, extruding and slicing to obtain modified polycarbonate.

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