Manufacturing method of recycled polycarbonate and recycled polycarbonate

Abstract

The present invention provides a method for producing recycled polycarbonate, and recycled polycarbonate.

Description

[Technical field]

[0001] The present invention relates to a method for producing recycled polycarbonate and recycled polycarbonate, and more particularly to a method for producing recycled polycarbonate utilizing a phenol end-capping agent.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS This specification claims the benefit of the filing date of Korean Patent Application No. 10-2021-0138175, filed with the Korean Intellectual Property Office on October 18, 2021, the entire contents of which are incorporated herein by reference. [Background technology]

[0003] Plastics are widely used in modern society because they are easy to process and their physical and chemical properties change easily. Among them, polycarbonate is one of the plastics that is widely used in various machines and electrical products because of its excellent mechanical properties such as insulation, impact resistance, and processability. To dispose of waste plastics that are discarded after use, landfilling or incineration is often used, but because plastics are difficult to decompose naturally, there is a risk of causing environmental problems such as water and soil pollution when they are landfilled, and there is a risk of causing environmental problems such as air pollution when they are incinerated.

[0004] In order to solve these environmental problems, many studies have been conducted to process, refine, or transform waste plastics for recycling, and some recycling methods are actually being used. However, the recycled plastics are not widely used because they are expensive and the purity of the plastics is not significantly improved. In addition, recycled plastics are processed and refined by mixing waste plastics of various colors, making it difficult to specify the desired physical and chemical properties and to realize the desired color.

[0005] Therefore, there is a continuing need for research into a method for producing recycled plastics that can significantly improve the purity of the recycled plastics while preventing the deterioration of mechanical properties. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Korean Patent Registration No. 10-2192506 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a method for producing recycled polycarbonate that can prevent deterioration of mechanical properties and greatly improve the purity of the recycled polycarbonate, and to provide the recycled polycarbonate. [Means for solving the problem]

[0008] One embodiment of the present invention provides a method for producing recycled polycarbonate, comprising the steps of: dissolving waste polycarbonate in a solvent to produce a first solution; adding a phenol end-capping agent to the first solution to produce a second solution; adding an adsorbent to the second solution to remove impurities from the second solution; adding a non-solvent to the second solution from which the impurities have been removed to precipitate a polycarbonate resin; and recovering the precipitated polycarbonate resin.

[0009] Yet another embodiment of the present invention provides a recycled polycarbonate produced by the above-mentioned method for producing recycled polycarbonate. Effect of the Invention

[0010] The recycled polycarbonate produced by the method for producing recycled polycarbonate of the present invention has no deterioration in mechanical properties, has high purity, and is effectively inhibited from yellowing. [Brief description of the drawings]

[0011] [Figure 1] The results of 1H-NMR analysis of the recycled polycarbonate of Comparative Example 1 are shown below. [Diagram 2] The results of 1H-NMR analysis of the recycled polycarbonate produced by the method for producing recycled polycarbonate of the present invention are shown below. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Specific embodiments will be described in more detail below.

[0013] One embodiment of the present invention provides a method for producing recycled polycarbonate, comprising the steps of: dissolving waste polycarbonate in a solvent to produce a first solution; adding a phenol end-capping agent to the first solution to produce a second solution; adding an adsorbent to the second solution to remove impurities from the second solution; adding a non-solvent to the second solution from which the impurities have been removed to precipitate a polycarbonate resin; and recovering the precipitated polycarbonate resin.

[0014] Polycarbonate is one of the plastics that is widely used in various machines and electrical products due to its excellent mechanical properties such as insulation, impact resistance, and processability. The backbone of polycarbonate is resistant to ultraviolet rays, oxygen (O 2 When degraded by exposure to oxygen or heat, fragments with phenol, aldehyde or benzyl alcohol terminals may be generated. Of these, phenol may cause yellowing during the extrusion or injection process when recycled polycarbonate is produced from waste polycarbonate, and may cause deterioration of mechanical properties.

[0015] The method for producing recycled polycarbonate according to the present invention can effectively prevent deterioration of mechanical properties and yellowing that may occur when producing recycled polycarbonate by protecting the phenol end groups present in the waste polycarbonate backbone with a phenol end-capper.

[0016] In one embodiment of the invention, the phenol end-capping agent is an anhydride or an acyl halide.

[0017] In one embodiment of the invention, the phenol end-capping agent is an anhydride.

[0018] In one embodiment of the invention, the anhydride is acetic anhydride or benzoic anhydride.

[0019] In one embodiment of the invention, the phenol end-capping agent is an acyl halide.

[0020] In one embodiment of the invention, the acyl halide is benzoyl chloride or 2,2-dimethylpropanoyl chloride.

[0021] In one embodiment of the present invention, the adsorbent is a combination of one or more selected from the group consisting of silica, alumina, activated carbon, acid clay, magnesium silicate, and aluminosilicate.

[0022] The adsorbent is specifically acid clay.

[0023] In one embodiment of the present invention, the adsorbent is contained in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the total weight of the second solution.

[0024] When the adsorbent is contained in the second solution in the above range, impurities contained in the second solution can be effectively removed.

[0025] In one embodiment of the present invention, the solvent is a cyclic ether solvent, a linear or cyclic carbonate solvent, a hydrocarbon solvent having 1 to 8 carbon atoms containing one or more halogens, methylpyrrolidone, dimethylformamide, or dimethylsulfoxide.

[0026] In one embodiment of the present specification, the cyclic ether solvent may be tetrahydrofuran, 1,4-dioxane or 1,3-dioxolane.

[0027] In one embodiment of the present invention, the linear carbonate solvent may be, but is not limited to, dimethyl carbonate (DMC), diethyl carbonate (DEC), dipropyl carbonate (DPC), ethyl propyl carbonate (EPC), ethyl methyl carbonate (EMC) or methyl propyl carbonate (MPC).

[0028] In one embodiment of the present invention, the cyclic carbonate solvent may be, but is not limited to, ethylene carbonate (EC), propylene carbonate (PC), 1,2-butylene carbonate (BC), 2,3-butylene carbonate, 1,2-pentylene carbonate, 2,3-pentylene carbonate, vinylene carbonate (VC), vinylethylene carbonate or fluoroethylene carbonate.Preferably, the cyclic carbonate solvent may be propylene carbonate.

[0029] In one embodiment of the present invention, the hydrocarbon solvent having 1 to 8 carbon atoms and containing one or more halogens may be, but is not limited to, dichloromethane, chloroform, tetrachloroethane, or ethylene dichloride.

[0030] In the present invention, the solvent may preferably be dichloromethane.

[0031] In the present invention, the non-solvent is a hydrocarbon compound containing one or more selected from the group consisting of alcohols, ketones, ethers, cycloalkanes, esters, carboxylic acids, and nitro groups.

[0032] The non-solvent refers to a compound having a Hansen Solubility Parameter (HSP) of 5 to 14 for the polycarbonate.

[0033] The Hansen solubility parameter for the polycarbonate can be calculated in consideration of the degree of bonding within the polycarbonate, specifically, from the non-polar dispersion bond, the dipole-dipole force, and the hydrogen bonding force.

[0034] Specifically, the compound having a Hansen Solubility Parameter (HSP) of 5 to 14 in polycarbonate is a hydrocarbon compound having 1 to 10 carbon atoms and containing one or more selected from the group consisting of alcohols, ketones, ethers, cycloalkanes, esters, carboxylic acids, and a nitro group.

[0035] More specifically, the compound having a Hansen Solubility Parameter (HSP) of 5 to 14 in polycarbonate is a hydrocarbon compound having 1 to 5 carbon atoms and containing one or more groups selected from the group consisting of alcohols, ketones, esters, and nitro groups.

[0036] In one embodiment of the invention, the non-solvent is acetone.

[0037] In one embodiment of the present invention, a catalyst may further be added to the first solution.

[0038] The catalyst can promote the esterification reaction of the phenol end groups contained in the waste polycarbonate under mild conditions such as room temperature.

[0039] The catalyst may be 4-dimethylaminopyridine (DMAP), 4-dimethylaminopyridine hydrochloride (DMAP·HCl), copper(II) tetrafluoroborate, or Cu(OTf) 2 The present invention is not limited to these.

[0040] Preferably, the catalyst is Cu(OTf) 2 may be also possible.

[0041] In one embodiment of the present invention, the phenol end-capping agent is contained in an amount of 0.1 parts by weight to 5 parts by weight based on 100 parts by weight of the total weight of the first solution.

[0042] Preferably, the phenol end-capping agent is contained in an amount of 0.1 part by weight to 1 part by weight based on 100 parts by weight of the total weight of the first solution.

[0043] When the phenol end-capping agent is contained in the first solution in the above-mentioned range of parts by weight, it can sufficiently react with the phenol end groups contained in the waste polycarbonate.

[0044] In one embodiment of the present invention, the step of recovering the precipitated polycarbonate resin includes the steps of: separating the precipitated polycarbonate resin with a filter; washing the precipitated polycarbonate resin; and drying the precipitated polycarbonate resin.

[0045] In the step of separating the precipitated polycarbonate resin using a filter, the mesh of the filter may be 1 μm to 10 μm.

[0046] Preferably, the mesh of the filter may be 3 μm to 7 μm.

[0047] The step of washing the precipitated polycarbonate resin may be performed using acetone. Specifically, the separated polycarbonate resin may be washed twice using 1 L of acetone.

[0048] The step of drying the precipitated polycarbonate resin may be performed in a vacuum oven at 40° C. for 16 hours.

[0049] One embodiment of the present invention provides recycled polycarbonate produced by the above-mentioned method for producing recycled polycarbonate.

[0050] In one embodiment of the present invention, the recycled polycarbonate has a phenol content of 0.5 mol % or less.

[0051] The lower the phenol content of the recycled polycarbonate, the better the quality of the recycled polycarbonate. The phenol content is preferably 0.2 mol % or less, and more preferably NMR detection limit or less.

[0052] In one embodiment of the present invention, the lower the phenol content of the recycled polycarbonate, the better. Therefore, the lower limit is not particularly limited, but may be, for example, 0.001 mol% or more.

[0053] When the phenol content of the recycled polycarbonate satisfies the above range, the phenol content in the recycled polycarbonate is very low, and the yellowing caused by phenol can be prevented. The degree of yellowing varies depending on the phenol content, and preferably, the yellowing is most reduced when the phenol content is reduced below the NMR detection limit.

[0054] The phenol content of the recycled polycarbonate can be calculated using 1H-NMR analysis. Specifically, trimethylsilane (TMS) was added as an internal standard, and CDCl 3After dissolving the recycled polycarbonate in a solvent at 20mg / ml, measurements can be made using an Agilent 500MHz device. The peak area at 7.18ppm in the measured 1H-NMR is determined as the 4H of the phenyl group of the polycarbonate, and the peak areas at 6.71ppm and 4.74ppm are determined as the phenyl group (2H) and hydroxyl group (1H) of phenol, respectively, to convert the phenol content in the recycled polycarbonate backbone into mol%.

[0055] In one embodiment of the present invention, the recycled polycarbonate has a yellowness index (YI) of 2.5 or less.

[0056] Specifically, the yellowness index (YI) of the recycled polycarbonate is 1 or more and 2.4 or less, 1.5 or more and 2.35 or less, or 1.95 or more and 2.34 or less.

[0057] When the yellowness of the recycled polycarbonate satisfies the above range, it can be confirmed that the yellowing phenomenon of the recycled polycarbonate is prevented.

[0058] The yellowness of the recycled polycarbonate can be measured by injection molding a test piece (width / length / thickness=60 mm / 40 mm / 3 mm) at 270° C. in accordance with ASTM D1925.

[0059] In one embodiment of the present invention, the weather resistance (ΔE) of the recycled polycarbonate is 20 or less.

[0060] The yellowing of the recycled polycarbonate represents a measure of weatherability.

[0061] The weather resistance (ΔE) can be calculated from the L', a' and b' values ​​measured again after measuring the L, a and b values ​​according to the ASTM D7869 method using a Weather-Ometer® machine and leaving the test piece under weather resistance conditions for 2,250 hours, according to the following Equation 2:

[0062]

number

[0063] In one embodiment of the present invention, the weather resistance (ΔE) of the recycled polycarbonate may be 20 or less, preferably 16 or less, 15.5 or less, 15.2 or less, or 10 or less.

[0064] The weather resistance (ΔE) is preferably lower, so the lower limit is not particularly limited, and may be, for example, 5 or more, 6 or more, or 8 or more.

[0065] In one embodiment of the present invention, the weight average molecular weight (Mw) of the recycled polycarbonate is 42,000 g / mol or more and 44,000 g / mol or less, but is not limited thereto.

[0066] More specifically, the weight average molecular weight of the recycled polycarbonate is 42,500 g / mol or more and 43,400 g / mol or less.

[0067] The weight average molecular weight can be measured using an Agilent 1200 series and calibrating with PC standard.

[0068] In one embodiment of the present invention, the melt index (MI) of the recycled polycarbonate may be 15 to 25. Specifically, the melt index of the recycled polycarbonate may be 20 to 21.

[0069] The melt index can be measured by ASTM D1238 at 300° C. using a 1.2 kg weight.

[0070] In one embodiment of the present invention, the waste polycarbonate is contained in an amount of 2 parts by weight to 20 parts by weight based on 100 parts by weight of a total weight of the first solution.

[0071] In one embodiment of the present invention, the solvent is contained in an amount of 80 parts by weight to 90 parts by weight based on 100 parts by weight of the total weight of the first solution.

[0072] When the waste polycarbonate and the solvent are contained in the first solution within the above ranges, precipitation of the waste polycarbonate does not occur and the first solution can be properly prepared.

[0073] In one embodiment of the present invention, in the step of dissolving the waste polycarbonate in a solvent to prepare a first solution, the waste polycarbonate is dissolved in the solvent for 1 hour to 3 hours.

[0074] Specifically, the waste polycarbonate is dissolved in the solvent for 1 hour and 30 minutes to 2 hours and 30 minutes, preferably for 2 hours.

[0075] In this manner, when the waste polycarbonate is dissolved in an organic solvent for 1 to 3 hours, the waste polycarbonate does not swell on the surface of the solvent and dissolves, but is well dissolved in the solvent, and the first solution can be properly prepared.

[0076] In one embodiment of the present invention, the step of dissolving the waste polycarbonate in a solvent to prepare the first solution may be carried out at room temperature. Specifically, it may be carried out at a temperature of 15° C. to 25° C. In this way, when the waste polycarbonate is dissolved in a solvent at a temperature of 15° C. to 25° C., the degree of vaporization of the solvent is low, and the desired first solution can be prepared without a significant change in the concentration of the solution.

[0077] In one embodiment of the present invention, the method for producing the recycled polycarbonate may further include a step of filtering the first solution after producing the first solution, and the mesh of the filter may be 0.45 μm to 10 μm.

[0078] In one embodiment of the present invention, the non-solvent is included in an amount of 30 parts by weight to 500 parts by weight based on 100 parts by weight of the total weight of the second solution.

[0079] When the non-solvent is contained in the second solution in the above range, impurities such as antioxidants or heat stabilizers can be effectively removed from the waste polycarbonate, and recycled polycarbonate can be obtained in a high yield.

[0080] The impurities refer to organic or inorganic dyes or pigments, heat stabilizers, antioxidants, UV stabilizers, flame retardants, antistatic agents, impact modifiers, plasticizers, lubricants, etc., other than polymer compounds added during the preparation of polycarbonate, but are not limited thereto, and may refer to all additives used in the art for preparing polycarbonate.

[0081] The antioxidant may be, for example, an Irgafos antioxidant, and the heat stabilizer may be, for example, a Tinuvin heat stabilizer.

[0082] The step of recovering the precipitated polycarbonate resin refers to filtering the solution obtained by adding a non-solvent to the second solution through a filter, and filtering the precipitated polycarbonate resin.

[0083] At this time, in the step of separating the precipitated polycarbonate resin using a filter, the mesh of the filter may be 1 μm to 10 μm, but is not limited thereto.

[0084] Figure 1 shows the 1H-NMR analysis results of the recycled polycarbonate of Comparative Example 1, which was not treated with a phenol end-capping agent. In Figure 1, the phenyl group peaks at 7.26 ppm and 7.18 ppm and the methyl group peak at 1.68 ppm corresponding to polycarbonate are clearly visible, and 6.74 ppm (2H) and 4.74 ppm (1H) corresponding to the phenol end groups are observed. The phenyl (2H) of the phenol end group overlapped with the polycarbonate peak and could not be identified.

[0085] Figure 2 shows the 1H-NMR analysis results of the recycled polycarbonate produced by the method of producing recycled polycarbonate of the present invention. In Figure 2, it can be observed that 6.74 ppm (2H) and 4.74 ppm (1H) corresponding to the phenol end groups are greatly reduced. EXAMPLES

[0086] The present invention will be illustrated in more detail below with reference to the following examples. The present invention is not limited to these examples, and the embodiments of the present invention may be modified into various other forms, and the scope of the present invention should not be interpreted as being limited to the following examples. The examples of the present invention are provided to more completely explain the present invention to those having average knowledge in the art.

[0087] Examples and Comparative Examples Example 1 360 g of waste polycarbonate was added to 2,040 g of dichloromethane, a solvent, in a reactor at room temperature (20° C.), and the waste polycarbonate was dissolved for 2 hours to prepare a first solution.

[0088] The first solution was added with 2.56 g of catalyst Cu(Otf) 2 was added and stirred at 300 rpm for 30 minutes.

[0089] Then, 7.23 g of acetic anhydride, a phenol end-capping agent, was gradually added to the first solution, and the mixture was stirred at room temperature (20° C.) for 6 hours at 300 rpm to prepare a second solution.

[0090] 18 g of acid clay, an adsorbent, was added to the second solution to remove impurities from the first solution, and the second solution containing the adsorbent was filtered using a 1 μm mesh filter to remove the adsorbent and impurities.

[0091] 2,400 ml of acetone, a non-solvent, was gradually added to the second solution to precipitate a polycarbonate resin. The precipitated polycarbonate resin was collected by filtering through a paper filter with a mesh of 5 μm, and washed twice with 1,000 ml of acetone.

[0092] Then, it was dried in a vacuum oven at 40℃ for 16 hours to obtain 298g of recycled polycarbonate (83% yield compared to the input waste polycarbonate).

[0093] Example 2 In the same manner as in Example 1, except that 16.03 g of benzoic anhydride was used as the phenol end-capping agent, 305 g of recycled polycarbonate was obtained (85% yield compared to the input of waste polycarbonate).

[0094] Example 3 In Example 1, 292 g of recycled polycarbonate was obtained in the same manner as in Example 1, except that 2.25 g of 4-(N,N-dimethylamino)pyridine (HCl) was used as the catalyst. (81% yield based on the amount of waste polycarbonate used)

[0095] Example 4 In Example 2, 295 g of recycled polycarbonate was obtained in the same manner as in Example 2, except that 2.25 g of 4-(N,N-dimethylamino)pyridine (HCl) was used as the catalyst. (82% yield based on the amount of waste polycarbonate used)

[0096] Example 5 In Example 3, 305 g of recycled polycarbonate was obtained in the same manner as in Example 3, except that 9.96 g of benzoic anhydride was used as the phenol end-capping agent (85% yield compared to the input of waste polycarbonate).

[0097] Example 6 In Example 3, 288 g of recycled polycarbonate was obtained in the same manner as in Example 3, except that 8.54 g of 2,2-dimethylpropanoyl chloride was used as the phenol end-capping agent (80% yield compared to the input waste polycarbonate).

[0098] Comparative Example 1 At room temperature (20° C.), 360 g of waste polycarbonate was added to 2,040 g of dichloromethane, a solvent, in a reactor, and the waste polycarbonate was dissolved for 2 hours to prepare a first solution.

[0099] 18 g of an adsorbent acid clay was added to the first solution to remove impurities from the first solution, and the first solution containing the adsorbent was filtered using a 1 μm mesh filter to remove the adsorbent and impurities.

[0100] Then, 2,400 ml of acetone, a non-solvent, was gradually added to the first solution to precipitate the polycarbonate resin. The precipitated polycarbonate resin was collected by filtering through a paper filter with a mesh of 5 μm, and washed twice with 1,000 ml of acetone.

[0101] Then, it was dried in a vacuum oven at 40℃ for 16 hours to obtain 302g of recycled polycarbonate (84% yield compared to the input waste polycarbonate).

[0102] Experimental Example The recycled polycarbonates prepared in the above examples and comparative examples were analyzed as follows, and the results are shown in Table 1 below.

[0103] Weight average molecular weight (Mw): Measured using Agilent 1200 series and calibrated with PC standard.

[0104] Melt index (MI): Measured according to ASTM D1238 at 300° C. using a weight of 1.2 kg.

[0105] -1H-NMR analysis of phenol content: Trimethylsilane (TMS) was added as an internal standard, and CDCl 3 The regenerated polycarbonate was dissolved in a solvent at 20 mg / ml, and then measured using an Agilent 500 MHz device.

[0106] Specifically, the peak area at 7.18 ppm in the measured NMR was determined to be the phenyl group 4H of the polycarbonate, and the peak areas seen at 6.71 ppm and 4.74 ppm were determined to be the phenyl group (2H) and hydroxyl group (1H), respectively, and the content of phenol present in the recycled polycarbonate backbone was converted to mol%. The width ratio of the phenyl peak of the phenol end group at 6.71 ppm (2H) was calculated based on the phenyl peak of the polycarbonate at 7.18 ppm (4H). The width ratio was converted to the number of protons and expressed as a percentage. This is shown in Equation 1 below.

[0107]

number

[0108] - Yellow Index (YI): According to ASTM D1925, a test piece (width / length / thickness=60 mm / 40 mm / 3 mm) was injection molded at 270°C to measure the YI value.

[0109] Weather resistance (△E): The weather resistance (△E) can be calculated by the following formula 2 using the L', a' and b' values ​​measured again after measuring the L, a and b values ​​according to ASTM D7869 method and then leaving the test piece under weather resistance conditions for 2,250 hours using a Weather-Ometer (registered trademark) machine.

[0110]

number

[0111] [Table 1]

[0112] As can be seen from the results in Table 1, the recycled polycarbonates of Examples 1 to 6 produced by the method for producing recycled polycarbonate according to the present invention had significantly lower phenol contents, lower yellowness index (YI) values, and lower weather resistance (△E) than the comparative examples, and were therefore able to effectively prevent yellowing.

[0113] On the other hand, the weight average molecular weight and melt index values ​​of Examples 1 to 6 were not significantly different from those of Comparative Example 1. This was because the polycarbonate backbone was not decomposed, and therefore there was no change in the physical properties of the weight average molecular weight and melt index.

Claims

1. Dissolving waste polycarbonate in a solvent to prepare a first solution; adding a phenol end-capping agent to the first solution to produce a second solution; adding an adsorbent to the second solution to remove impurities from the second solution; adding a non-solvent to the second solution from which the impurities have been removed to precipitate a polycarbonate resin; and recovering the precipitated polycarbonate resin; A method for producing recycled polycarbonate, comprising:

2. The method for producing recycled polycarbonate according to claim 1, wherein the phenol end-capping agent is an anhydride or an acyl halide.

3. The method for producing recycled polycarbonate according to claim 1, wherein the adsorbent is a combination of one or more selected from the group consisting of silica, alumina, activated carbon, acid clay, magnesium silicate, and aluminosilicate.

4. The method for producing recycled polycarbonate according to claim 1, wherein the adsorbent is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the total weight of the second solution.

5. The method for producing recycled polycarbonate according to claim 2, wherein the anhydride is acetic anhydride or benzoic anhydride.

6. The method for producing recycled polycarbonate according to claim 2, wherein the acyl halide is benzoyl chloride or 2,2-dimethylpropanoyl chloride.

7. The method for producing recycled polycarbonate according to claim 1, wherein the solvent is a cyclic ether solvent, a linear or cyclic carbonate solvent, a hydrocarbon solvent having 1 to 8 carbon atoms and containing one or more halogens, methylpyrrolidone, dimethylformamide, or dimethylsulfoxide.

8. The method for producing recycled polycarbonate according to claim 1, wherein the non-solvent is a hydrocarbon compound containing one or more selected from the group consisting of alcohols, ketones, ethers, cycloalkanes, esters, carboxylic acids, and nitro groups.

9. The method for producing recycled polycarbonate according to claim 1, further comprising adding a catalyst to the first solution.

10. The method for producing recycled polycarbonate according to claim 1, wherein the phenol end-capping agent is contained in an amount of 0.1 to 5 parts by weight based on 100 parts by weight of the total weight of the first solution.

11. The step of recovering the precipitated polycarbonate resin comprises: separating the precipitated polycarbonate resin using a filter; washing the precipitated polycarbonate resin; and drying the precipitated polycarbonate resin; A method for producing the recycled polycarbonate according to claim 1, comprising:

12. The method for producing recycled polycarbonate according to claim 1, wherein the waste polycarbonate is contained in an amount of 2 to 20 parts by weight based on 100 parts by weight of a total weight of the first solution.

13. The method for producing recycled polycarbonate according to claim 1, wherein the non-solvent is included in an amount of 30 parts by weight to 500 parts by weight based on 100 parts by weight of a total weight of the second solution.

14. The method for producing recycled polycarbonate according to claim 1, wherein the phenol content of the recycled polycarbonate is 0.5 mol% or less.

15. The method for producing recycled polycarbonate according to claim 1, wherein the yellowness index (YI) of the recycled polycarbonate is 2.5 or less.

16. The method for producing recycled polycarbonate according to claim 1, wherein the weather resistance (ΔE) of the recycled polycarbonate is 20 or less.

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