Method for producing regenerated polycarbonate resin

Abstract

Provided is a production method with which it is possible to produce a regenerated polycarbonate resin having good color tone and mechanical properties. A method for producing a regenerated polycarbonate resin according to the present invention comprises: a step (S1) for obtaining a polycarbonate resin solution by dissolving a waste polycarbonate resin starting material in a good solvent; a step (S2) for bringing the polycarbonate resin solution into contact with a coagulant and then removing insoluble substances to obtain a solution (L) from which the insoluble substances have been removed; a step (S3) for precipitating the regenerated polycarbonate resin by mixing the solution (L) with a poor solvent; and a step (S4) for recovering the precipitated regenerated polycarbonate resin.

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a recycled polycarbonate resin. Background Art

[0002] Polycarbonate resin is a resin having excellent mechanical properties such as heat resistance and impact resistance, excellent dimensional stability, and excellent transparency. A polycarbonate resin composition containing polycarbonate resin is used for various applications.

[0003] However, waste polycarbonate resin compositions are sometimes deteriorated by use and ultraviolet rays, resulting in a decrease in hue and mechanical properties. In addition, polycarbonate resin compositions mostly contain additives, inorganic substances, and other polymers in addition to polycarbonate resin, and it is difficult to separate them. Therefore, the recycling use of waste polycarbonate resin compositions is limited and mostly disposable.

[0004] For sustainable development, it is important to recycle polycarbonate resin to recycle resources. As a recycling method of polycarbonate resin, there are roughly three methods such as material recycling to recycle into polycarbonate resin material, chemical recycling to recycle into bisphenol as a raw material of polycarbonate resin, and thermal recycling to use as energy. Patent Document 1 discloses decomposition of polycarbonate resin to bisphenol A as a raw material. Patent Document 2 discloses a method of dissolving polycarbonate resin in a solvent, removing insoluble substances, and then precipitating polycarbonate resin by adding an organic solvent. In Patent Document 3, a technique of dissolving polycarbonate in a solvent and then precipitating it is disclosed in the same manner as in Patent Document 2.

[0005] Prior Art Documents

[0006] Patent Documents

[0007] Patent Document 1: Japanese Unexamined Patent Application Publication No. 2022-75133

[0008] Patent Document 2: Japanese Unexamined Patent Application Publication No. 11-152371

[0009] Patent Document 3: Japanese Unexamined Patent Application Publication No. 2004-182746 Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] The method described in Patent Document 1 relates to chemical recycling of decomposing polycarbonate resin to raw material bisphenol, and the load in decomposition and purification is larger than that of material recycling.

[0012] The methods described in Patent Documents 2 and 3 involve material recycling, which can be said to be a method simpler than chemical recycling. On the other hand, in material recycling, since it is difficult to separate additives and deteriorated components, the hue and mechanical properties of the regenerated polycarbonate resin sometimes become insufficient for practical use. As described above, polycarbonate resins are also widely used in applications that require mechanical properties and transparency. For such applications, good hue and mechanical properties are required for the regenerated polycarbonate resin obtained by material recycling. However, Patent Documents 2 and 3 hardly mention the physical properties of the regenerated polycarbonate resin.

[0013] The present invention has been completed in view of such circumstances, and an object thereof is to provide a method for producing a regenerated polycarbonate resin capable of producing a regenerated polycarbonate resin having good hue and mechanical properties.

[0014] Means for Solving the Problems

[0015] The inventors of the present invention repeatedly conducted in-depth studies to solve the above problems, and as a result, found that the following invention meets the above object, and thus completed the present invention. That is, the present invention relates to the following inventions.

[0016] <1> A method for producing a regenerated polycarbonate resin, which produces a regenerated polycarbonate resin from a waste polycarbonate resin raw material, characterized in that the production method includes the following steps (S1) to (S4).

[0017] Step (S1): A step of dissolving the waste polycarbonate resin raw material in a soluble good solvent to obtain a polycarbonate resin solution

[0018] Step (S2): A step of bringing the polycarbonate resin solution into contact with a flocculant, removing insoluble matters, and obtaining a solution (L) from which insoluble matters have been removed

[0019] Step (S3): A step of precipitating the regenerated polycarbonate resin by mixing the solution (L) with a poor solvent

[0020] Step (S4): A step of recovering the precipitated regenerated polycarbonate resin

[0021] <2> The method for producing a regenerated polycarbonate resin according to the above <1>, including a step of bringing the polycarbonate resin solution into contact with a filter aid before removing insoluble matters in the step (S2).

[0022] <3> The method for producing a regenerated polycarbonate resin according to the above <1> or <2>, wherein the waste polycarbonate resin raw material contains a total of 5% by mass or more of one or more polycarbonate resin compositions equivalent to those selected from the group consisting of the following (i) to (iii), and the waste polycarbonate resin raw material contains 10% by mass or more of a polycarbonate resin.

[0023] (i) A polycarbonate resin composition having a transmittance at 500 nm of 90% or less when the transmittance is measured using a 50-mm sample cell for a solution obtained by dissolving in dichloromethane to a concentration of 10% by mass.

[0024] (ii) A polycarbonate resin composition having a nitrogen atom content of 50 mass ppm or more.

[0025] (iii) A polycarbonate resin composition having a phosphorus atom content of 5 mass ppm or more.

[0026]

[0026] <4> The method for producing a recycled polycarbonate resin according to any one of <1> to <3> above, wherein the good solvent used in the step (S1) contains a halogen-based solvent and / or a phenol-based solvent.

[0027] <5> The method for producing a recycled polycarbonate resin according to any one of <1> to <4> above, wherein the poor solvent used in the step (S3) contains any one selected from the group consisting of a ketone-based solvent, a saturated hydrocarbon-based solvent, an alcohol-based solvent, and water.

[0028] <6> The method for producing a recycled polycarbonate resin according to any one of <1> to <5> above, wherein the coagulant in the step (S2) is one or more selected from the group consisting of iron(III) chloride, iron(I) sulfate, iron(II) sulfate, aluminum chloride, aluminum sulfate, titanium oxide, copper(I) sulfate, copper(II) sulfate, copper(I) chloride, copper(II) chloride, zinc sulfate, an anionic polymer compound, a cationic polymer compound, and a nonionic polymer compound.

[0029] <7> The method for producing a recycled polycarbonate resin according to <6> above, wherein the coagulant in the step (S2) is one or more selected from the group consisting of iron(III) chloride, iron(II) sulfate, iron(III) sulfate, aluminum sulfate, aluminum chloride, polyacrylamide, and polyethylene oxide.

[0030] <8> The method for producing a recycled polycarbonate resin according to <2> above, wherein the filter aid is one or more selected from the group consisting of activated carbon, montmorillonite, diatomaceous earth, silica gel, and a synthetic adsorbent.

[0031] <9> The method for producing a recycled polycarbonate resin according to any one of <1> to <8> above, wherein the total content of Na, Mg, and Al in the recycled polycarbonate resin is 0.3 mass ppm or more and 20 mass ppm or less (preferably 0.3 mass ppm or more and 15 mass ppm or less, more preferably 0.5 mass ppm or more and 12 mass ppm or less, and further preferably 1.0 mass ppm or more and 10 mass ppm or less).

[0032] <10>The method for producing a recycled polycarbonate resin according to any one of <1> to <9> above, wherein the L value of the recycled polycarbonate resin based on reflection measurement is 80 or more.

[0033] <11>The method for producing a recycled polycarbonate resin according to any one of <1> to <10> above, wherein the tensile nominal strain of the recycled polycarbonate resin is 60% or more.

[0034] <x1>A method for manufacturing a molded body, comprising: a step of obtaining a recycled polycarbonate resin by the method for manufacturing a recycled polycarbonate resin according to any one of the foregoing <1> to <11>; and a step of obtaining a molded body using the foregoing recycled polycarbonate resin.

[0035] Advantages of the Invention

[0036] According to the present invention, a recycled polycarbonate resin having good hue and mechanical properties can be manufactured. Detailed Description of Embodiments

[0037] Embodiments of the present invention will be described in detail below. However, the description of the constituent elements described below is an example (representative example) of the embodiments of the present invention, and the present invention is not limited to the following content as long as its gist is not changed. In addition, when the expression "~” is used in this specification, it is used as an expression including numerical values or physical property values before and after it.

[0038] In addition, when only "ppm” is described, it means "mass ppm”.

[0039] <Method for Manufacturing Recycled Polycarbonate Resin>

[0040] The present invention relates to a method for manufacturing a recycled polycarbonate resin by using a waste polycarbonate resin raw material (hereinafter, sometimes referred to as "the manufacturing method of the present invention”). The foregoing manufacturing method includes the following steps (S1) to (S4).

[0041] Step (S1): A step of dissolving the foregoing waste polycarbonate resin composition in a soluble good solvent to obtain a polycarbonate resin solution

[0042] Step (S2): A step of contacting the foregoing polycarbonate resin solution with a coagulant, removing insoluble matters, and obtaining a solution (L) from which insoluble matters have been removed

[0043] Step (S3): A step of precipitating the foregoing recycled polycarbonate resin by mixing the foregoing solution (L) with a poor solvent

[0044] Step (S4): A step of recovering the precipitated foregoing recycled polycarbonate resin

[0045] The manufacturing method of the present invention manufactures a recycled polycarbonate resin through material recycling. That is, in the manufacturing method of the present invention, instead of chemically decomposing the waste polycarbonate resin raw material of the raw material, after removing deteriorated substances of the polycarbonate resin, etc., it is regenerated into a polycarbonate resin again.

[0046] One of the features of the manufacturing method of the present invention is that after the polycarbonate resin solution is brought into contact with a coagulant, impurities are removed to produce a precipitate. By adopting such a method, impurities can be adsorbed and coagulated and removed. Therefore, even if a waste polycarbonate resin raw material that affects the hue is used, a recycled polycarbonate resin showing a hue that is not problematic in practical use can be manufactured. In addition, a polycarbonate resin having good weather resistance and mechanical properties can be obtained. According to the manufacturing method of the present invention, even if a raw material containing other components such as other resins and additives in addition to the polycarbonate resin is used, other components can be efficiently removed to obtain a recycled polycarbonate resin having a hue that is not problematic in practical use, etc.

[0047] Hereinafter, each process will be described.

[0048] [Process (S1)]

[0049] Process (S1) is a process of dissolving a waste polycarbonate resin raw material in a good solvent to obtain a polycarbonate resin solution.

[0050] [Waste polycarbonate resin raw material]

[0051] The waste polycarbonate resin raw material is a post-consumer material and / or a pre-consumer material of a polycarbonate resin composition. The waste polycarbonate resin raw material preferably contains a total of 5% by mass or more of one or more polycarbonate resin compositions equivalent to those selected from the group consisting of the following (i) to (iii).

[0052] (i) A polycarbonate resin composition having a transmittance at 500 nm of 90% or less when measuring the transmittance of a solution obtained by dissolving it in dichloromethane to a concentration of 10% by mass using a 50 mm sample cell

[0053] (ii) A polycarbonate resin composition having a nitrogen atom content of 50 ppm by mass or more

[0054] (iii) A polycarbonate resin composition having a phosphorus atom content of 5 ppm by mass or more

[0055] As a representative of the polycarbonate resin composition satisfying the above (i), a polycarbonate resin added with a dye, a pigment, carbon black, titanium oxide, etc. can be cited. Compounds such as dyes, pigments, and carbon black are very difficult to remove in the recycling of conventional materials, and it is not easy to regenerate a polycarbonate resin having a good hue from such a polycarbonate resin composition.

[0056] As a representative of the polycarbonate resin composition satisfying the above (ii), a polycarbonate resin to which a nitrogen atom-containing compound such as an ultraviolet absorber is added can be cited. When such a polycarbonate resin composition is used for a long time, the nitrogen atom-containing compound deteriorates, which causes the polycarbonate resin composition to be colored. In the conventional material recycling, it is difficult to remove the compound that causes coloring, and it remains in the recycled polycarbonate resin, resulting in coloring.

[0057] As a representative of the polycarbonate resin composition satisfying the above (iii), a polycarbonate resin to which a phosphorus atom-containing compound such as a phosphorus-based flame retardant is added can be cited. If such a polycarbonate resin composition is used for a long time, it is speculated that the phosphorus atom-containing compound erodes the resin due to hydrolysis, which causes the mechanical strength of the resin to deteriorate. In the conventional material recycling, it is difficult to remove such a flame retardant, which may be the main cause of the deterioration of the mechanical strength of the recycled polycarbonate resin.

[0058] From the above, it can be seen that in the case of recycling polycarbonate resin from a polycarbonate resin composition, additives such as pigments, dyes, ultraviolet absorbers, and flame retardants added to improve the properties of the polycarbonate resin are preferably removed in terms of hue and mechanical strength. The manufacturing method of the present invention can remove these impurities.

[0059] In particular, when the waste polycarbonate resin raw material contains 5% by mass or more of a polycarbonate resin composition satisfying one or more of the above (i) to (iii), the influence on the hue of the obtained recycled polycarbonate resin is large, and it is very difficult to obtain a recycled polycarbonate resin with good hue in the conventional material recycling. On the other hand, in the manufacturing method of the present invention, even when a polycarbonate resin composition satisfying one or more of the above (i) to (iii) is mixed in an amount of 5% by mass or more and used as a waste polycarbonate resin raw material, it can be recycled into a polycarbonate resin with good hue. Therefore, it can be said that a waste polycarbonate resin raw material containing 5% by mass or more of a polycarbonate resin composition satisfying one or more of the above (i) to (iii) is suitable as a raw material for the manufacturing method of the present invention.

[0060] In addition, as described later, considering the ease of dissolution and operability, as the waste polycarbonate resin raw material, a pulverized product of a polycarbonate resin composition satisfying one or more of the above (i) to (iii) in an amount of 5% by mass or more is preferably used.

[0061] A polycarbonate resin composition is a composition containing a polycarbonate resin. In addition to the single polycarbonate resin, polymer alloys such as polymer mixtures of a polycarbonate resin and other resins can also be cited. In addition, the polycarbonate resin composition may contain two or more polycarbonate resins with different compositions and molecular weights. As other resins, copolymer resins such as ABS resin and AS resin, which are copolymers of acrylonitrile, butadiene, and styrene, polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), and acrylic resins (PMMA) can be cited.

[0062] The polycarbonate resin composition usually contains additives and the like corresponding to the purpose. The content of the polycarbonate resin in the polycarbonate resin composition is, for example, 20 to 100% by mass, preferably 50 to 100% by mass. The polycarbonate resin may be a homopolymer of the same structural unit or a copolymer containing different structural units. As additives, glass fiber, carbon fiber, pigment, dye, ultraviolet absorber, flame retardant, etc. can be cited.

[0063] The aforementioned waste polycarbonate resin raw material preferably contains 10% by mass or more of the polycarbonate resin, preferably 20% by mass or more, and more preferably 30% by mass or more.

[0064] The polycarbonate resin usually contains the repetition of a bisphenol unit and a carbonate unit, that is, a structural unit represented by the following formula (A). The content of the structural unit represented by the following formula (A) is usually 20 mol% or more, preferably 30 mol% or more, and more preferably 40 mol% or more.

[0065] [Chemical Formula 1]

[0066]

[0067] In formula (A), X is any one selected from the group consisting of a single bond, an alkylene group having 2 to 8 carbon atoms, a cycloalkylene group having 5 to 15 carbon atoms, an alkylidene group having 1 to 8 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms, a fluorenylidene group, a xanthenylidene group, a thioxanthenylidene group, -O-, -S-, -CO-, -SO-, and -SO2.

[0068] The alkylene group having 2 to 8 carbon atoms can be either substituted or unsubstituted, and can be linear or branched. As the alkylene group having 2 to 8 carbon atoms, ethane-1,2-diyl, propane-1,2-diyl, propane-1,3-diyl, butane-1,2-diyl, butane-1,4-diyl, hexane-1,2-diyl, hexane-1,6-diyl, etc. can be cited.

[0069] The C5-C15 subcycloalkyl group can be either substituted or unsubstituted. Examples of the C5-C15 subcycloalkyl group include cyclopropane-1,2-diyl and cyclohexane-1,2-diyl.

[0070] The C1-C8 alkylidene group can be either substituted or unsubstituted, and can be linear or branched. The C1-C8 alkylidene group is preferably a group represented by the following formula (1a).

[0071] [Chemical formula 2]

[0072]

[0073] R a and R b each independently represent a hydrogen atom, an alkyl group having 1 to 7 carbon atoms, a cycloalkyl group having 3 to 7 carbon atoms, an alkoxy group having 1 to 7 carbon atoms, or an aryl group having 6 to 7 carbon atoms. They can be either substituted or unsubstituted. Examples include: hydrogen atom, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, isopentyl, n-hexyl, n-heptyl, 2-ethylhexyl, methoxy, ethoxy, n-propoxy, isopropoxy, n-butoxy, isobutoxy, tert-butoxy, n-pentyloxy, isopentyloxy, n-hexyloxy, n-heptyloxy, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, benzyl, phenyl, tolyl, etc.

[0074] The C5-C15 cycloalkylidene group can be either substituted or unsubstituted. Examples of the C5-C15 cycloalkylidene group include: cyclopropane-1,1-diyl, cyclobutane-1,1-diyl, cyclopentane-1,1-diyl, cyclohexane-1,1-diyl, 3,3,5-trimethylcyclohexane-1,1-diyl, cyclohept

[0075] ane-1,1-diyl, cyclooctane-1,1-diyl, cyclononane-1,1-diyl, cyclodecane-1,1-diyl, cycloundecane-1,1-diyl, cyclododecane-1,1-diyl, etc.

[0076] In formula (A), X is preferably a C1-C8 alkylidene group, a C5-C15 cycloalkylidene group, or a fluorenylidene group, more preferably a C1-C8 alkylidene group, and even more preferably propane-2,2-diyl.

[0077] In formula (A), R 1 and R 2 are each independently any one selected from the group consisting of a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryl group having 6 to 12 carbon atoms. When n and m are 2 or more, multiple R 1 and R 2 They may be the same group or different groups. Additionally, the alkyl group having 1 to 12 carbon atoms, the cycloalkyl group having 1 to 12 carbon atoms, the alkoxy group having 1 to 12 carbon atoms, and the aryl group having 6 to 12 carbon atoms may be either substituted or unsubstituted.

[0078] As R 1 、R 2 , for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a methyl group, an ethyl group, a n-propyl group, an isopropyl group, a n-butyl group, an isobutyl group, a tert-butyl group, a n-pentyl group, an isopentyl group, a n-hexyl group, a n-heptyl group, a n-octyl group, a n-nonyl group, a n-decyl group, a n-undecyl group, a n-dodecyl group, a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, a cycloheptyl group, a cyclooctyl group, a cyclododecyl group, a methoxy group, an ethoxy group, a n-propoxy group, an isopropoxy group, a n-butoxy group, an isobutoxy group, a tert-butoxy group, a n-pentyloxy group, an isopentyloxy group, a n-hexyloxy group, a n-heptyloxy group, a n-octyloxy group, a n-nonyloxy group, a n-decyloxy group, a n-undecyloxy group, a n-dodecyloxy group, a benzyl group, a phenyl group, a tolyl group, a 2,6-dimethylphenyl group, etc. can be cited.

[0079] R 1 、R 2 Preferably, they are each independently an alkyl group having 1 to 12 carbon atoms, and more preferably, they are each independently an alkyl group having 1 to 5 carbon atoms.

[0080] In formula (A), n and m are each independently an integer of 0 to 3. n and m are preferably each independently 0 to 2, and more preferably each independently 0 or 1.

[0081] Among them, formula (A) is preferably the following formula (A2).

[0082] [Chemical formula 3]

[0083]

[0084] In formula (A2), X has the same meaning as in formula (A). The preferred manner is also the same as that of formula (A). In formula (A2), X is preferably an alkylidene group having 1 to 8 carbon atoms, a cycloalkylidene group having 5 to 15 carbon atoms, or a fluorenylidene group, more preferably an alkylidene group having 1 to 8 carbon atoms, and further preferably propane-2,2-diyl.

[0085] In formula (A2), R 3 is any one selected from the group consisting of a hydrogen atom, a halogen atom, an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 1 to 12 carbon atoms, an alkoxy group having 1 to 12 carbon atoms, and an aryl group having 6 to 12 carbon atoms. R 3 is preferably a hydrogen atom or an alkyl group having 1 to 12 carbon atoms, more preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and further preferably a hydrogen atom or a methyl group.

[0086] In formula (A2), preferably X is propane-2,2-diyl, and R 3 is a hydrogen atom or a methyl group.

[0087] Specifically, examples of the bisphenol unit of the structural unit represented by the above formula (A) include substances of bisphenols such as 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 3,3-bis(4-hydroxyphenyl)pentane, 3,3-bis(4-hydroxy-3-methylphenyl)pentane, 2,2-bis(4-hydroxyphenyl)pentane, 2,2-bis(4-hydroxy-3-methylphenyl)pentane, 3,3-bis(4-hydroxyphenyl)heptane, 3,3-bis(4-hydroxy-3-methylphenyl)heptane, 2,2-bis(4-hydroxyphenyl)heptane, 2,2-bis(4-hydroxy-3-methylphenyl)heptane, 4,4-bis(4-hydroxyphenyl)heptane, 4,4-bis(4-hydroxy-3-methylphenyl)heptane, etc., but are not limited to any of them.

[0088] Among them, the bisphenol unit of the structural unit represented by the above formula (A) is preferably a structure selected from any one of the group consisting of 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, and 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, more preferably a structure derived from 2,2-bis(4-hydroxyphenyl)propane or 2,2-bis(4-hydroxy-3-methylphenyl)propane, and particularly preferably a structure derived from 2,2-bis(4-hydroxyphenyl)propane.

[0089] Post-consumer materials used as raw materials for waste polycarbonate resins are usually used polycarbonate resin compositions that have been assembled into products as molded articles or used by consumers indoors and outdoors as outer packaging. Examples of the molded articles using the polycarbonate resin composition include the housings of electronic devices, sundries, lighting lamps, interior and exterior decorations for automobiles, handling containers, building materials, etc. In addition, as pre-consumer materials, it includes purification resins generated by polymerization and compounding, polycarbonate resins with unqualified product quality, etc.

[0090] From the perspective of environmental load, it is preferable to use post-consumer materials as the raw material of waste polycarbonate resin. As the usage time (the time of being used) of the post-consumer material, it is preferably 3 years or more, more preferably 5 years or more, and further preferably 7 years or more. If the usage time is too short, although the polycarbonate resin has not deteriorated yet, it is still recycled, so it is not preferable from the aspect of environmental load. In addition, if the usage time is too long, the polycarbonate resin deteriorates significantly, and even if it is regenerated, it may not be possible to fully restore its physical properties. Therefore, as the usage time, it is preferably 30 years or less, more preferably 20 years or less.

[0091] The raw material of waste polycarbonate resin can be directly used in the form of a resin composition that is a post-consumer material or a pre-consumer material, or can be appropriately divided into an appropriate size by cutting, crushing, grinding, etc. The dividing methods such as cutting, crushing, and grinding are not particularly limited, and the following methods can be used: cutting using a cutting tool; fusing by cutting with gas, plasma, laser, etc.; severing; cutting using a shredder; coarse crushing to 20 cm or less using a jaw crusher or a rotary crusher; medium crushing to 1 cm or less using a rotary crusher, a cone crusher, or a mill; grinding to 1 mm or less using a mill, etc. These methods can be carried out alone or in combination of multiple methods.

[0092] When the shape of the raw material of waste polycarbonate resin is too large, the dissolution time becomes long, which is not preferable. Therefore, it is preferable to use a pulverized body obtained by pulverizing the polycarbonate resin composition as the raw material of waste polycarbonate resin. The pulverized body of the polycarbonate resin composition preferably has a shape of 53 mm or less, more preferably 22.4 mm or less, and still more preferably 11.2 mm or less. On the other hand, if the shape is too small, it may fly as dust when put into the device, so it is preferably 2.8 mm or more, more preferably 4.75 mm or more.

[0093] It should be noted that "53 mm or less" means passing through a sieve with a nominal mesh size of 53 mm specified in JIS-Z-8801-1 (2019), "22.4 mm or less" means passing through a sieve with a nominal mesh size of 22.4 mm, and "11.2 mm or less" means passing through a sieve with a nominal mesh size of 11.2 mm. In addition, "2.8 mm or more" means not passing through a sieve with a nominal mesh size of 2.8 mm, and "4.75 mm or more" means not passing through a sieve with a nominal mesh size of 4.75 mm.

[0094] (Good solvent)

[0095] The good solvent for dissolving the waste polycarbonate resin raw material is not particularly limited as long as it can dissolve the waste polycarbonate resin raw material, and preferably contains a halogen-based solvent and / or a phenol-based solvent. Examples of the halogen-based solvent include dichloromethane and dichloroethane. Examples of the phenol-based solvent include phenol, cresol, xylenol, ethylphenol, propylphenol, butylphenol, methoxyphenol, ethoxyphenol, propoxyphenol, butoxyphenol, benzylphenol, phenylphenol, chlorophenol, dichlorophenol, chloromethylphenol, etc. The ratio of the halogen-based solvent and / or the phenol-based solvent can be any ratio as long as it is the ratio for dissolving the waste polycarbonate resin raw material. The total of them is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more with respect to the good solvent. That is, when the good solvent contains a halogen-based solvent and does not contain a phenol-based solvent, the ratio of the halogen-based solvent with respect to the good solvent is preferably in the aforementioned range. When the good solvent contains a phenol-based solvent and does not contain a halogen-based solvent, the ratio of the phenol-based solvent with respect to the good solvent is preferably in the aforementioned range. When the good solvent contains a halogen-based solvent and a phenol-based solvent, the total ratio of the halogen-based solvent and the phenol-based solvent with respect to the good solvent is preferably in the aforementioned range.

[0096] The good solvent may also contain solvents other than the halogen-based solvent and the phenol-based solvent. Specifically, examples include: aromatic hydrocarbon-based solvents such as toluene and xylene; cyclohexanone; tetrahydrofuran (THF); acetonitrile; dimethyl carbonate; hexafluoroisopropanol; water, etc. The good solvent can use these solvents in appropriate combinations to dissolve the waste polycarbonate resin raw material at the dissolution temperature.

[0097] Regarding the amount of the good solvent, with respect to the mass of the waste polycarbonate resin raw material, it is preferably 200% by mass or more, more preferably 250% by mass or more, and further preferably 350% by mass or more. When the ratio of the good solvent is small, the viscosity of the solution becomes extremely high, stirring and dissolution become difficult, the filtration rate decreases during filtration, or the filtrate adheres to the filter material, which may lead to a decrease in the yield. In addition, the amount of the good solvent with respect to the mass of the waste polycarbonate resin raw material is preferably 5000% by mass or less, more preferably 4000% by mass or less, and further preferably 3000% by mass or less. When the ratio of the good solvent is large, the solubility with respect to the polycarbonate resin becomes large, and even when a poor solvent is added in step (S3), more polycarbonate resins that do not precipitate in the state of being dissolved in the good solvent increase, and as a result, the yield may deteriorate. Therefore, the amount of the good solvent with respect to the mass of the waste polycarbonate resin raw material is preferably 200 to 5000% by mass, more preferably 250 to 4000% by mass, and further preferably 350 to 3000% by mass.

[0098] (Dissolution temperature)

[0099] When dissolving the waste polycarbonate resin raw material in a good solvent, it is preferable to control the temperature (the temperature of the solution in the dissolution tank). Without controlling the temperature, the dissolution time becomes non-uniform, and when feeding the liquid to the next process, undissolved components etc. will be generated. As the temperature, it is preferably below the boiling point of the good solvent. If it exceeds the boiling point of the good solvent, a condenser is required for the dissolution tank and the process becomes complicated. As the temperature of the specific good solvent (the temperature of the solution in the dissolution tank), it is preferably 10°C or higher, more preferably 15°C or higher, and further preferably 20°C or higher. When the temperature is too low, the solubility of the polycarbonate resin decreases and the dissolution takes time. In addition, when feeding the liquid to the next process, sometimes the liquid feeding takes time, or a large load is imposed on the filtration during filtration. In addition, it is preferably 140°C or lower, more preferably 130°C or lower, and further preferably 120°C or lower. When the temperature is too high, the polycarbonate resin will deteriorate due to heat and may be colored. Therefore, the dissolution temperature is preferably 10 to 140°C, more preferably 15 to 130°C, and further preferably 20 to 120°C.

[0100] (Dissolution time)

[0101] The dissolution time is preferably 20 minutes or longer, more preferably 40 minutes or longer, and further preferably 1 hour or longer. In addition, it is preferably 5 hours or shorter, more preferably 4 hours or shorter, and further preferably 3 hours or shorter. If the dissolution time is too short, the amount of undissolved components increases, and the yield may decrease or blockages etc. may occur in the process. When it is too long, decomposition and coloring of the polymer may occur. Therefore, the dissolution time is preferably 20 minutes to 5 hours, more preferably 40 minutes to 4 hours, and further preferably 1 hour to 3 hours.

[0102] [Process (S2)]

[0103] Process (S2) is a process of bringing the aforementioned polycarbonate resin solution into contact with a flocculant, removing insoluble matters, and obtaining a solution (L) from which insoluble matters have been removed.

[0104] The purpose of the implementation process (S2) is to easily remove insolubles. As described above, the waste polycarbonate resin raw material contains various additives in addition to the polycarbonate resin composition. Among them, the particle sizes of carbon black, titanium oxide, etc. used for coloring are very small and are not captured by the filter when the insolubles are removed by filter filtration, and the insolubles remain in the filtrate. In addition, even if the insolubles are sedimented by centrifugation or the like, they do not sediment and are difficult to remove by centrifugation. Especially for the colored polycarbonate resin composition, the pigment as the colorant cannot be removed, and as a result, the coloring component remains in the recycled polycarbonate resin, leading to deterioration of the hue. The deterioration of the hue causes the recycled polycarbonate resin with transparency to be unable to be molded, and in addition, the recycled molded body cannot be colored into the desired color. Therefore, the utilization range of the recycled polycarbonate resin is narrowed. From the above, in the process (S2), the purpose is to promote the aggregation of fine insolubles by bringing the flocculant into contact with the polycarbonate resin solution. The manufacturing method of the present invention is characterized in that, through this process, the insolubles can be captured when filtered by a filter, or the insolubles can be sedimented by centrifugation or the like, thereby removing the insolubles.

[0105] (Flocculant)

[0106] The main reason for the small particle size of the insolubles is that the insolubles are dispersed due to the charge repulsion between the insolubles. The flocculant plays the following role: by neutralizing the charges of the insolubles dispersed in the polycarbonate resin solution, it promotes the adsorption and aggregation of the insolubles to each other, increasing the particle size of the insolubles. From the above, any inorganic salt can be used as long as it can be ionized and decompose the polycarbonate resin in the polycarbonate resin solution other than alkali metal salts and alkaline earth metal salts. Among them, iron(III) chloride, iron(I) sulfate, iron(II) sulfate, aluminum chloride, aluminum sulfate, titanium oxide, copper(I) sulfate, copper(II) sulfate, copper(I) chloride, copper(II) chloride, zinc sulfate, etc. are preferred. In addition, a commercially available mixture of inorganic salts can also be used as the flocculant. Inorganic salts can neutralize charges, but when the particle size of the aggregated particles is small, a high molecular compound such as an anionic high molecular compound, a cationic high molecular compound, or a nonionic high molecular compound can also be added. This is because the insolubles dispersed in the polycarbonate resin solution adhere to the polymer chain, increasing the particle size. In addition, the high molecular compound can be used alone or as a flocculant. Representative examples of the high molecular compound include polyacrylamide and polyethylene oxide.

[0107] Therefore, the flocculant in step (S2) is preferably at least one selected from the group consisting of iron(III) chloride, iron(I) sulfate, iron(II) sulfate, aluminum chloride, aluminum sulfate, titanium oxide, copper(I) sulfate, copper(II) sulfate, copper(I) chloride, copper(II) chloride, zinc sulfate, anionic polymer compounds, cationic polymer compounds, and nonionic polymer compounds, and more preferably at least one selected from the group consisting of iron(III) chloride, iron(II) sulfate, iron(III) sulfate, aluminum sulfate, aluminum chloride, polyacrylamide, and polyethylene oxide.

[0108] The method of contacting the polycarbonate resin solution with the flocculant is not particularly limited. The flocculant can be mixed during the preparation of the polycarbonate resin solution in step (S1), or the polycarbonate resin solution can be contacted with the flocculant after the polycarbonate resin solution is prepared in step (S1).

[0109] For example, in step (S1), the waste polycarbonate resin raw material, good solvent, and flocculant can be mixed, and while dissolving the polycarbonate resin in the good solvent, it can be contacted with the flocculant. In addition, when contacting the polycarbonate resin solution with the flocculant after the polycarbonate resin solution is prepared in step (S1), the flocculant can be directly added to the polycarbonate resin solution for contact, or the flocculant can be loaded on the filter material and contacted with the polycarbonate resin solution. In addition, the flocculant can be loaded in a column shape, and the polycarbonate resin solution can be made to flow therein for contact.

[0110] Among them, a method of directly adding the flocculant to the polycarbonate resin solution for contact after step (S1) is preferred.

[0111] When contacting the polycarbonate resin solution with the flocculant after the polycarbonate resin solution is prepared in step (S1), the contact time between the polycarbonate resin solution and the flocculant is preferably 5 minutes or more, more preferably 10 minutes or more, and further preferably 20 minutes or more. If it is too short, the flocculation effect may not be fully exerted. In addition, the contact time of the flocculant is preferably within 3 hours, more preferably within 2 hours. If it is too long, the particles flocculated at one time may be dispersed due to stirring or the like. Therefore, the contact time with the flocculant is preferably 5 minutes to 3 hours, more preferably 10 minutes to 3 hours, and further preferably 20 minutes to 2 hours.

[0112] When contacting the polycarbonate resin solution with the flocculant after the polycarbonate resin solution is prepared in step (S1), the contact temperature between the polycarbonate resin solution and the flocculant can be the same as the temperature during dissolution in step (S1), preferably 20°C or more, and preferably 140°C or less. If the temperature is too high, the polycarbonate resin may be colored. If the temperature is too low, flocculation may not occur. Therefore, it is further preferably 30°C or more and 90°C or less.

[0113] The usage amount of the flocculant is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, relative to the mass of the dissolved waste polycarbonate resin raw material. When the usage amount of the flocculant is too small, the aggregation of insoluble matters cannot be sufficiently promoted, and it may not be possible to remove the insoluble matters. In addition, the usage amount of the flocculant is preferably 20% by mass or less, further preferably 10% by mass or less, relative to the mass of the dissolved waste polycarbonate resin raw material. When the amount of the flocculant is too large, the flocculant itself remains in the recycled polycarbonate resin, which may be the main cause of coloring. Therefore, the usage amount of the flocculant is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, relative to the mass of the dissolved waste polycarbonate resin raw material.

[0114] (Filter aid)

[0115] In the production method of the present invention, a filter aid can be used in combination with the flocculant. The production method of the present invention preferably includes a step of bringing the polycarbonate resin solution into contact with the filter aid before removing the insoluble matters in step (S2). The method of bringing the polycarbonate resin solution into contact with the filter aid can be the same as or different from the method of bringing the polycarbonate resin solution into contact with the flocculant. The contact between the polycarbonate resin solution and the filter aid can be carried out simultaneously with the flocculant or not simultaneously. That is, the polycarbonate resin solution can be brought into contact with the flocculant and the filter aid simultaneously, or the filter aid can be brought into contact after bringing the polycarbonate resin solution into contact with the flocculant, or the flocculant can be brought into contact after bringing the polycarbonate resin solution into contact with the filter aid. Thus, by using the flocculant and the filter aid in combination, it is possible to more efficiently remove deteriorated products, foreign resins, additives, contaminants, etc. contained in the polycarbonate resin composition.

[0116] The filter aid used in the present invention is preferably at least one selected from the group consisting of activated carbon, diatomaceous earth, montmorillonite, silica gel, and synthetic adsorbents.

[0117] As the shape of the activated carbon, powder, granular (crushed, granular, spherical, cylindrical, etc.), fibrous, etc. can be cited, and any shape can be used. In addition, as the raw material of the activated carbon, any one of sawdust, coconut shell, coal, charcoal, etc. can be used. The activated carbon can be activated carbon that has been activated by methods such as gas activation method, steam activation method, and chemical activation method.

[0118] As montmorillonite, bentonite, activated clay, etc. can be cited. As activated clay, Galleon Earth (registered trademark), Galleonite (registered trademark), Celite manufactured by Mizusawa Chemical Industry Co., Ltd., Nikkanite manufactured by ToShin Chemical Co., Ltd., etc. can be cited.

[0119] The synthetic adsorbent is a crosslinked polymer having a porous structure. As the synthetic adsorbent, aromatic series, aromatic modified type, methacrylic acid series, etc. can be cited, and any one of them can be used. Specifically, Sepabeads (registered trademark) manufactured by Mitsubishi Chemical Corporation, etc. can be cited.

[0120] The method of contacting the polycarbonate resin solution with the filter aid is not particularly limited. The filter aid can be mixed during the preparation of the polycarbonate resin solution. In addition, after the polycarbonate resin solution is prepared, the filter aid can be directly added to the polycarbonate resin solution for contact, or it can be loaded on the filter material to contact the polycarbonate resin solution, or the filter aid can be loaded in a columnar form to allow the polycarbonate resin solution to flow through it for contact. In addition, these methods can also be appropriately combined so that the polycarbonate resin solution contacts the filter aid one or more times.

[0121] The amount of the filter aid used can be any amount as long as it can sufficiently adsorb coloring components and impurities. When the filter aid is directly added, the amount used is preferably 0.1% by mass or more, more preferably 0.5% by mass or more, based on the mass of the dissolved waste polycarbonate resin raw material. When the amount of the filter aid is too small, it may not be possible to sufficiently remove coloring components and impurities. In addition, the amount of the filter aid used is preferably 30% by mass or less, preferably 20% by mass or less, based on the mass of the dissolved waste polycarbonate resin raw material. When the amount of the filter aid is too large, it may not be possible to sufficiently remove the filter aid, and as a result, coloring may deteriorate. Therefore, when the filter aid is directly added, the amount of the filter aid used is preferably 0.1 to 30% by mass, more preferably 0.5 to 20% by mass, based on the mass of the dissolved waste polycarbonate resin raw material.

[0122] On the other hand, when it is spread on the filter material or loaded in a columnar form, it is preferably 20% by mass or more, more preferably 40% by mass or more, based on the mass of the dissolved waste polycarbonate resin raw material. When the amount of the filter aid is too small, it may not be possible to sufficiently remove coloring components and impurities. In addition, the amount of the filter aid used is preferably 5000% by mass or less, more preferably 2000% by mass or less, based on the mass of the dissolved waste polycarbonate resin raw material. When the amount of the filter aid is too large, impurity components eluted from the filter aid may be contained in a large amount in the recycled polycarbonate resin. Therefore, when it is spread on the filter material, the amount of the filter aid used is preferably 20 to 5000% by mass, more preferably 40 to 2000% by mass, based on the mass of the dissolved waste polycarbonate resin raw material.

[0123] The filter aid can be reused repeatedly by regeneration before and after use. In the regeneration of the filter aid before and after use, the filter aid can be washed with steam, heat, or an organic solvent. By washing, the impurities contained in the filter aid are removed, which is sometimes effective in reducing the impurities in the obtained regenerated polycarbonate resin.

[0124] The flocculant and the filter aid are preferably a combination of one or more flocculants selected from the group consisting of iron(III) chloride, iron(I) sulfate, iron(II) sulfate, aluminum chloride, aluminum sulfate, titanium oxide, copper(I) sulfate, copper(II) sulfate, copper(I) chloride, copper(II) chloride, zinc sulfate, anionic polymer compounds, cationic polymer compounds, and nonionic polymer compounds, and one or more filter aids selected from the group consisting of activated carbon, diatomaceous earth, montmorillonite, silica gel, and synthetic adsorbents. More preferably, it is a combination of one or more flocculants selected from the group consisting of iron(III) chloride, iron(II) sulfate, iron(III) sulfate, aluminum sulfate, aluminum chloride, polyacrylamide, and polyethylene oxide, and one or more filter aids selected from the group consisting of activated carbon, diatomaceous earth, montmorillonite, silica gel, and synthetic adsorbents.

[0125] (Removal of insolubles)

[0126] As a method for removing insolubles from the polycarbonate resin solution, methods using a filter such as filtration, centrifugation, and cyclone filtration can be cited; methods of performing solid-liquid separation from the insolubles by sedimentation separation, centrifugation, flotation separation, etc., and taking out the liquid side. In the case of removing insolubles using a filter, any of filter paper, glass filter, bag filter, candle filter, etc. can be used. In addition, the filter can also be used in multiple stages and multiple methods. As the minimum mesh size of the filter material, it is preferably 5 μm or less, more preferably 2 μm or less, and further preferably 1 μm or less. When the mesh is too large, the removal of foreign substances becomes insufficient, and when it is too small, the filterability tends to deteriorate. In addition, in order to improve the filterability, an aromatic hydrocarbon solvent can be added during the removal of insolubles. For example, after supplying the aromatic hydrocarbon solvent to the polycarbonate resin solution, the insolubles can be removed through the filter material, or the polycarbonate resin solution and the aromatic hydrocarbon solvent can be passed through the filter material in parallel to remove the insolubles.

[0127] [Step (S3)]

[0128] Step (S3) is a step of precipitating the aforementioned regenerated polycarbonate resin by mixing the aforementioned solution (L) with a poor solvent.

[0129] (Poor solvent)

[0130] The poor solvent that can be used to precipitate the recycled polycarbonate resin is not particularly limited as long as it can precipitate the recycled polycarbonate resin. Examples of the poor solvent include ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone (MIBK), and cyclohexanone; saturated hydrocarbon solvents such as hexane, heptane, and cyclohexane; alcohol solvents such as methanol, ethanol, and isopropyl alcohol; water; toluene, xylene; THF; acetonitrile; dimethyl carbonate; hexafluoroisopropanol, etc.

[0131] The poor solvent preferably contains one or more selected from the group consisting of ketone solvents, saturated hydrocarbon solvents, alcohol solvents, and water, and more preferably contains any one or more selected from the group consisting of acetone, ethanol, water, methanol, isopropyl alcohol, hexane, cyclohexane, heptane, and MIBK. Among them, acetone has a low boiling point, so solvent recovery and the like become easy, so it is preferred.

[0132] The ratio of one or more solvents selected from the group consisting of ketone solvents, saturated hydrocarbon solvents, alcohol solvents, and water can be any ratio as long as it is the ratio for precipitating the polycarbonate resin. Relative to the total poor solvent, their total is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more.

[0133] The mass of the poor solvent relative to the waste polycarbonate resin raw material is preferably 200% by mass or more, more preferably 250% by mass or more, and further preferably 350% by mass or more. When the ratio of the poor solvent is small, precipitation may not occur sufficiently, or the fluidity may decrease in the subsequent step (S4). In addition, the poor solvent is preferably 5000% by mass or less, more preferably 4000% by mass or less, and further preferably 3000% by mass or less, relative to the waste polycarbonate resin raw material. When the ratio of the poor solvent is large, the polycarbonate resin may also dissolve in the poor solvent, resulting in a possible deterioration of the yield. Therefore, the amount of the poor solvent relative to the mass of the waste polycarbonate resin raw material is preferably 200 to 5000% by mass, more preferably 250 to 4000% by mass, and further preferably 350 to 3000% by mass.

[0134] When adding a poor solvent to precipitate the recycled polycarbonate resin, it is preferable to control the temperature (the solution temperature in the apparatus). Without controlling the temperature, the precipitation time becomes non-uniform, and when feeding the liquid to the next process, sometimes the precipitation is insufficient and the yield deteriorates. As the temperature during the precipitation operation, it is preferably below the boiling points of the good solvent and the poor solvent. If it exceeds the boiling points of the good solvent and the poor solvent, the solubility of the polycarbonate resin will increase, and it will be difficult to sufficiently recover the polycarbonate resin. As the specific solution temperature (the solution temperature in the apparatus) during the precipitation operation, it is preferably 10°C or higher, more preferably 15°C or higher, and further preferably 20°C or higher. When the temperature is too low, when feeding the liquid to the next process, sometimes the feeding takes time, or a large load is imposed on the filtration during filtration. In addition, it is preferably 140°C or lower, more preferably 130°C or lower, and further preferably 120°C or lower. When the temperature is too high, the polycarbonate resin will deteriorate due to heat and may be colored. Therefore, the temperature for precipitating the recycled polycarbonate resin is preferably 10 to 140°C, more preferably 15 to 130°C, and further preferably 20 to 120°C.

[0135] The good solvent and the poor solvent are preferably a combination of a good solvent containing a halogen-based solvent and / or a phenol-based solvent and a poor solvent containing any one selected from the group consisting of a ketone-based solvent, a saturated hydrocarbon-based solvent, an alcohol-based solvent, and water, and more preferably the aforementioned combination and the good solvent and the poor solvent are each 200% by mass or more and 5000% by mass or less relative to the waste polycarbonate resin raw material.

[0136] The ratio of the poor solvent to the good solvent is preferably 0.4 times or more, more preferably 1 time or more, and in addition, preferably 2 times or less. If the ratio of the poor solvent to the good solvent is too small, the amount of precipitated recycled polycarbonate resin will be small, and if it is too large, there is a possibility that the process becomes excessive and the solvent recovery load becomes large. Therefore, the ratio of the poor solvent to the good solvent is preferably 0.4 to 2 times, more preferably 1 to 2 times.

[0137] [Process (S4)]

[0138] Process (S4) is a process for recovering the precipitated recycled polycarbonate resin.

[0139] (Trapping of recycled polycarbonate resin)

[0140] Through process (S3), a suspension in which the precipitated recycled polycarbonate resin is suspended in a solvent (good solvent and poor solvent) is obtained. The recycled polycarbonate resin in this suspension can be trapped by methods such as centrifugation and filtration. The temperature of the suspension is preferably 10°C or higher and 120°C or lower. If it is too low, the viscosity increases, and if the temperature is too high, there is a possibility of resin deterioration.

[0141] Since the recovered recycled polycarbonate resin contains solvents (good solvents, poor solvents), it is preferably dried under reduced pressure or normal pressure. As the drying temperature, it is preferably 30 to 120 °C. When the drying temperature is too low, the drying takes time, and when it is too high, there is a possibility of causing deterioration of the polycarbonate resin.

[0142] (The solvents used)

[0143] The solvents used in each stage are preferably separated by distillation or membranes and reused as good solvents and poor solvents, respectively. In addition, when reusing, 2 to 30% by mass can be discarded. When the discarded amount is small, impurities in the process remain, which may increase the impurities in the recycled polycarbonate resin. On the other hand, when the discarded amount is too large, more solvents are used, resulting in a greater environmental load.

[0144] It should be noted that steps (S1) to (S4) can also be repeated multiple times. That is, the recycled polycarbonate resin recovered in step (S4) can be redissolved in a good solvent, treated with a coagulant, and then a poor solvent is added to precipitate it. In each step, the same solvent or different solvents can be used. When steps (S1) to (S4) are repeated, the number of times can be appropriately determined according to the use, etc., taking, for example, the L value, Na, Mg, Al content, etc. of the recycled polycarbonate resin described below as indicators. By repeating steps (S1) to (S4) multiple times, the impurities contained in the recycled polycarbonate become less. On the other hand, when it is excessive, the recovery amount may decrease. Therefore, when steps (S1) to (S4) are repeated, the number of times is preferably 2 to 3 times.

[0145] [Recycled polycarbonate resin]

[0146] The recycled polycarbonate resin obtained by the method for producing a recycled polycarbonate resin of the present invention contains the structural unit represented by the above formula (A) and preferably has the following characteristics.

[0147] (L value)

[0148] The L value of the recycled polycarbonate resin based on reflection measurement is preferably 80 or more, more preferably 85 or more, and further preferably 90 or more. When the L value is low, when the recycled polycarbonate resin is molded into a molded product, the color tone difference or transparency is low.

[0149] It should be noted that the L value of the recycled polycarbonate resin based on reflection measurement can be measured by a reflection mode using a spectrocolorimeter (for example, Spectrophotometer SE6000 manufactured by Nippon Denshoku Industries Co., Ltd.).

[0150] (N content)

[0151] The content of nitrogen atoms in the recycled polycarbonate resin is preferably 6 mass ppm or less, more preferably 5 mass ppm or less, and still more preferably 3 mass ppm or less. The content of the nitrogen atoms can be measured using a trace total nitrogen analyzer.

[0152] (P content)

[0153] The content of phosphorus atoms in the recycled polycarbonate resin is preferably 10 mass ppm or less, more preferably 5 mass ppm or less, and still more preferably 2 mass ppm or less. The content of the phosphorus atoms can be determined by inductively coupled plasma mass spectrometry (ICP-MS).

[0154] (Na, Mg, Al content)

[0155] The total content of Na, Mg, and Al in the recycled polycarbonate resin is, for example, 20 mass ppm or less, preferably 15 mass ppm or less, more preferably 12 mass ppm or less, and still more preferably 10 mass ppm or less. If a large amount of Na, Mg, and Al is contained in the polycarbonate resin, there is a tendency for the hue to deteriorate during molding. In addition, the total content of Na, Mg, and Al in the recycled polycarbonate resin is preferably 0.3 mass ppm or more, more preferably 0.5 mass ppm or more, and still more preferably 1.0 mass ppm or more. When the content is too small, although the hue becomes good, in order to achieve this hue, multiple cleanings etc. are required, resulting in poor efficiency and a high possibility of reduced yield.

[0156] It should be noted that the total content of Na, Mg, and Al in the recycled polycarbonate resin can be measured by inductively coupled plasma mass spectrometry (ICP-MS). Therefore, the total content of Na, Mg, and Al in the recycled polycarbonate resin is preferably 0.3 mass ppm or more and 15 mass ppm or less, more preferably 0.5 mass ppm or more and 12 mass ppm or less, and still more preferably 1.0 mass ppm or more and 10 mass ppm or less.

[0157] (3mm YI)

[0158] The YI (yellow index) of a 3 mm thick plate molded body of the recycled polycarbonate resin is preferably 3.0 or less, more preferably 2.9 or less, and still more preferably 2.7 or less. When the YI is too high, it becomes a yellowish substance, and the applicable uses are often restricted.

[0159] It should be noted that the YI can be measured in accordance with ASTM D1925.

[0160] (Tensile nominal strain)

[0161] The tensile nominal strain of the recycled polycarbonate resin is preferably 60% or more, more preferably 70% or more, and still more preferably 80% or more. When the tensile nominal strain is small, there is a possibility that cracks or the like may occur during the molding process or use of the molded product, making it brittle.

[0162] Regarding the tensile nominal strain of the recycled polycarbonate resin, a dumbbell-shaped resin plate with a total length of 75 mm, a parallel part length of 30 mm, a parallel part width of 5 mm, a thickness of 2 mm, and a clamping part width of 10 mm can be molded to obtain a test piece, and the measurement is carried out in accordance with ISO527.

[0163] [Usage method of recycled polycarbonate resin]

[0164] As a material with a small environmental load, the recycled polycarbonate resin can be used for the same uses as the unused polycarbonate resin. For example, the recycled polycarbonate resin can be widely used for uses such as casings, screens of mobile phones, automotive interior / exterior trims, displays, medical devices, building materials, etc.

[0165] The recycled polycarbonate resin can be used alone in a total amount of 100% to form a molded body, or can be used in combination with waste polycarbonate resin and unused (new) polycarbonate resin. In addition, additives can be blended, or a polymer alloy with other resins other than polycarbonate resin can be formed. Regarding the additives and alloys, commonly used additives and alloys can be appropriately used.

[0166] The recycled polycarbonate resin can be used, for example, in a method for manufacturing a molded body having a process of obtaining a recycled polycarbonate resin by the manufacturing method of the recycled polycarbonate resin of the present invention and a process of obtaining a molded body using the obtained recycled polycarbonate resin. Thus, a molded body containing the recycled polycarbonate resin can be obtained. Examples of the molded body include pellets; members or products such as casings, automotive interior / exterior trim members, display members, medical device members, building materials, etc. The method for obtaining the molded body can be the same as the method used for the conventional use of unused polycarbonate resin, and other resins and additives can be appropriately blended. The members or products can be manufactured using the recycled polycarbonate resin, and can also be manufactured using the pellets formed from the recycled polycarbonate resin.

[0167] Examples

[0168] Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited to the following examples as long as its gist is not changed.

[0169] [Waste polycarbonate resin raw material]

[0170] · PC(1): Ground product of the polycarbonate housing of a smart meter used outdoors (transmittance at 500 nm: 0%, nitrogen content: 2 mass ppm, phosphorus content: 1.1 mass%)

[0171] · PC(2): Ground product of a used polycarbonate shed (transmittance at 500 nm: 52%, nitrogen content: 86 mass ppm, phosphorus content: 38 mass ppm)

[0172] · PC(3): Ground product of a used projector (PC / ABS) (transmittance at 500 nm: 0%, nitrogen content: N.D. (not detected), phosphorus content: 0.82 mass%)

[0173] Each raw material was previously ground to about 10 mm square using a crusher before use.

[0174] [Evaluation]

[0175] (Transmittance at 500 nm)

[0176] Regarding the transmittance at 500 nm, a solution was prepared by dissolving the waste polycarbonate resin raw material at a concentration of 10 mass% in dichloromethane. Using a 50 mm sample cell, the transmittance was measured using a Shimadzu UV1800 to obtain the transmittance at 500 nm.

[0177] (Nitrogen content)

[0178] The nitrogen content of the waste polycarbonate resin raw material or recycled polycarbonate resin was measured using a trace total nitrogen analyzer TN-10 (manufactured by Dia Instruments Co., Ltd.).

[0179] (Phosphorus content)

[0180] The phosphorus content was determined by wet decomposition of the waste polycarbonate resin raw material or recycled polycarbonate resin by adding sulfuric acid, nitric acid, and hydrogen peroxide water, followed by recovery with pure water and volume adjustment. Then, it was measured using an ICP emission device ("5800 ICP-OES" manufactured by Agilent Technologies, Inc.).

[0181] (L value)

[0182] After placing the obtained recycled polycarbonate resin in a circular sample cell, it was covered with a ZERO BOX and measured in reflection mode using a spectrophotometer SE6000 manufactured by Nippon Denshoku Industries Co., Ltd. to obtain the L value.

[0183] (Quantification of Na, Mg, Al)

[0184] Weigh 200 mg of the obtained recycled polycarbonate resin, and perform pressurized closed decomposition using nitric acid through a microwave pretreatment device (Multiwave 7000 manufactured by Anton Paar). Then, after volume fixation and appropriate dilution, perform ICP-MS quantitative determination using ELEMENT2 manufactured by Thermo Fisher Scientific.

[0185] (3mm YI)

[0186] Using the obtained recycled polycarbonate resin as the raw material, use a small injection molding machine (Shinko SELLBICC Co., Ltd., Mobile) to mold a plate with a thickness of 3 mm, a length of 25 mm, and a width of 25 mm. Use this plate as a test piece, and use a spectrophotometer (CM-3700d manufactured by Konica Minolta Inc.) to measure the yellow index (YI) according to ASTM D1925.

[0187] (Tensile nominal strain)

[0188] Using the obtained recycled polycarbonate resin as the raw material, use a small injection molding machine (Shinko SELLBIC C Co., Ltd., Mobile). At a barrel temperature of 280 °C and a mold temperature of 60 °C, mold a dumbbell-shaped resin plate with a total length of 75 mm, a parallel part length of 30 mm, a parallel part width of 5 mm, a thickness of 2 mm, and a clamping part width of 10 mm. Use this dumbbell-shaped resin plate as a test piece, and use a universal testing machine AGS-5kNX (manufactured by Shimadzu Corporation) to measure the tensile nominal strain.

[0189] [Example 1]

[0190] In a 10 L flask, supply 500 g of the pulverized product of PC(1) and 4.5 kg of dichloromethane under a nitrogen atmosphere at 20 °C, and stir for 30 minutes (step (1)). Then, add 5 g of iron(III) chloride as a coagulant to the solution, continue stirring for 60 minutes, and then filter the solution through a 0.5 μm glass filter to obtain a filtrate (step (2)). Add 4.5 kg of acetone to the filtrate, and as a result, a white precipitate is formed (step (3)). Filter the polycarbonate precipitate (recycled polycarbonate resin) with filter paper, and dry it in a dryer at 40 °C for 10 hours to obtain a powder of the recycled polycarbonate resin (step (4)).

[0191] For the obtained recycled polycarbonate resin, perform each evaluation according to the above steps. The results are shown in Table 1.

[0192] [Example 2]

[0193] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of phenol were supplied under a nitrogen atmosphere at 60 °C, and stirred for 30 minutes (step (1)). Then, 15 g of iron(II) sulfate, which is a flocculant, was added to the solution, and after continuing to stir for 60 minutes, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (step (3)). The polycarbonate precipitate (regenerated polycarbonate resin) was filtered off with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the regenerated polycarbonate resin (step (4)).

[0194] For the obtained regenerated polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 1.

[0195] [Example 3]

[0196] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of dichloromethane were supplied under a nitrogen atmosphere at 20 °C, and stirred for 30 minutes (step (1)). Then, 15 g of iron(III) sulfate, which is a flocculant, was added to the solution, and after continuing to stir for 60 minutes, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (step (3)). The polycarbonate precipitate (regenerated polycarbonate resin) was filtered off with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the regenerated polycarbonate resin (step (4)).

[0197] For the obtained regenerated polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 1.

[0198] [Example 4]

[0199] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of phenol were supplied under a nitrogen atmosphere at 80 °C, and stirred for 30 minutes (step (1)). Then, 25 g of aluminum sulfate, which is a flocculant, was added to the solution at 60 °C, and after continuing to stir for 60 minutes, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (step (3)). The polycarbonate precipitate (regenerated polycarbonate resin) was filtered off with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the regenerated polycarbonate resin (step (4)).

[0200] For the obtained regenerated polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 1.

[0201] [Example 5]

[0202] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of dichloromethane were supplied under a nitrogen atmosphere at 20 °C, and stirred for 30 minutes (Step (1)). Next, 25 g of aluminum chloride as a coagulant was added to the solution, and after continuing to stir for 60 minutes, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (Step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (Step (3)). The polycarbonate precipitate (recycled polycarbonate resin) was collected by filtration with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the recycled polycarbonate resin (Step (4)).

[0203] For the obtained recycled polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 1.

[0204] [Example 6]

[0205] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of phenol were supplied under a nitrogen atmosphere at 60 °C, and stirred for 30 minutes (Step (1)). Next, 25 g of polyethylene oxide as a coagulant was added to the solution, and after continuing to stir for 60 minutes, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (Step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (Step (3)). The polycarbonate precipitate (recycled polycarbonate resin) was collected by filtration with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the recycled polycarbonate resin (Step (4)).

[0206] For the obtained recycled polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 1.

[0207] [Example 7]

[0208] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of a solvent prepared by mixing phenol and toluene in a mass ratio of 1:1 were supplied under a nitrogen atmosphere at 80 °C, and stirred for 30 minutes (Step (1)). Next, at 60 °C, 5 g of iron(II) sulfate as a coagulant was added to the solution, and after stirring for 10 minutes, 5 g of polyacrylamide was added, and after further continuing to stir for 60 minutes, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (Step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (Step (3)). The polycarbonate precipitate (recycled polycarbonate resin) was collected by filtration with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the recycled polycarbonate resin (Step (4)).

[0209] For the obtained recycled polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 1.

[0210] [Example 8]

[0211] In a 10 L flask, 500 g of the pulverized product of PC(2) was supplied under a nitrogen atmosphere at 80 °C, and 4.5 kg of a solvent obtained by mixing phenol and toluene in a mass ratio of 3:7 was added, followed by stirring for 30 minutes (step (1)). Then, at 60 °C, 5 g of iron(III) chloride as a coagulant was added to the solution, and after continuing to stir for 60 minutes, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (step (3)). The polycarbonate precipitate (recycled polycarbonate resin) was collected by filtration with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the recycled polycarbonate resin (step (4)).

[0212] For the obtained recycled polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 1.

[0213] [Example 9]

[0214] In a 10 L flask, 500 g of the pulverized product of PC(3) was supplied under a nitrogen atmosphere at 80 °C, and 4.5 kg of a solvent obtained by mixing phenol and toluene in a mass ratio of 1:1 was added, followed by stirring for 30 minutes (step (1)). Then, at 60 °C, 5 g of iron(II) sulfate as a coagulant was added to the solution, and after continuing to stir for 60 minutes, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (step (3)). The polycarbonate precipitate (recycled polycarbonate resin) was collected by filtration with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the recycled polycarbonate resin (step (4)).

[0215] For the obtained recycled polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 1.

[0216] [Table 1]

[0217]

[0218] [Example 10]

[0219] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of dichloromethane were supplied under a nitrogen atmosphere at 80 °C, and stirred for 30 minutes (step (1)). Then, at 60 °C, 5 g of activated carbon was added to the solution, and after stirring for 30 minutes, 5 g of iron(III) chloride as a coagulant was added to the solution, and stirring was continued for 60 minutes. Then, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (step (3)). The polycarbonate precipitate (regenerated polycarbonate resin) was collected by filtration with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the regenerated polycarbonate resin (step (4)).

[0220] For the obtained regenerated polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 2.

[0221] [Example 11]

[0222] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of phenol were supplied under a nitrogen atmosphere at 80 °C, and stirred for 30 minutes (step (1)). Then, at 60 °C, 5 g of activated carbon and 5 g of iron(II) sulfate as a coagulant were added to the solution, and stirring was continued for 90 minutes. Then, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (step (3)). The polycarbonate precipitate (regenerated polycarbonate resin) was collected by filtration with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the regenerated polycarbonate resin (step (4)).

[0223] For the obtained regenerated polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 2.

[0224] [Example 12]

[0225] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of a solvent obtained by mixing phenol and toluene in a mass ratio of 3:7 were supplied under a nitrogen atmosphere at 80 °C, and stirred for 30 minutes (step (1)). Then, at 60 °C, 5 g of activated carbon and 5 g of iron(II) sulfate as a coagulant were added to the solution, and stirring was continued for 90 minutes. Then, the solution was filtered through a 0.5 μm glass filter to obtain a filtrate (step (2)). 4.5 kg of acetone was added to the filtrate, and as a result, a white precipitate was formed (step (3)). The polycarbonate precipitate (regenerated polycarbonate resin) was collected by filtration with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the regenerated polycarbonate resin (step (4)).

[0226] For the obtained recycled polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 2.

[0227] [Table 2]

[0228]

[0229] [Comparative Example 1]

[0230] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of dichloromethane were supplied under a nitrogen atmosphere at 20 °C, and stirred for 30 minutes. The solution was filtered through a glass filter, and as a result, the filter was colored black, but a black filtrate was obtained. 4.5 kg of acetone was added to the filtrate, and as a result, a precipitate was formed. The polycarbonate precipitate (recycled polycarbonate resin) was filtered off with a filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the recycled polycarbonate resin (step (4)).

[0231] For the obtained recycled polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 3.

[0232] [Comparative Example 2]

[0233] In a 10 L flask, 500 g of the pulverized product of PC(2) and 4.5 kg of dichloromethane were supplied under a nitrogen atmosphere at 20 °C, and stirred for 30 minutes. The solution was filtered through a glass filter, and as a result, a filtrate was obtained. 4.5 kg of acetone was added to the filtrate, and as a result, a precipitate was formed. The polycarbonate precipitate (recycled polycarbonate resin) was filtered off with a filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the recycled polycarbonate resin (step (4)).

[0234] For the obtained recycled polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 3.

[0235] [Comparative Example 3]

[0236] In a 10 L flask, 500 g of the pulverized product of PC(3) and 4.5 kg of phenol were supplied under a nitrogen atmosphere at 80 °C, and stirred for 30 minutes. The solution was filtered through a glass filter, and as a result, the filter was colored black, but a blackish filtrate was obtained. 4.5 kg of acetone was added to the filtrate, and as a result, a precipitate was formed. The polycarbonate precipitate (recycled polycarbonate resin) was filtered off with a filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the recycled polycarbonate resin (step (4)).

[0237] For the obtained recycled polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 3.

[0238] [Comparative Example 4]

[0239] In a 10 L flask, 500 g of the pulverized product of PC(1) and 4.5 kg of dichloromethane were supplied under a nitrogen atmosphere at 20 °C, and stirring was carried out for 30 minutes. Then, 5 g of activated carbon was added to the solution at 60 °C, and after stirring for 60 minutes, the solution was filtered through a glass filter. As a result, the filter was colored black, and a filtrate was obtained. 4.5 kg of acetone was added to the filtrate, and as a result, a precipitate was formed. The polycarbonate precipitate (regenerated polycarbonate resin) was collected by filtration with filter paper and dried in a dryer at 40 °C for 10 hours to obtain a powder of the regenerated polycarbonate resin (step (4)).

[0240] For the obtained regenerated polycarbonate resin, each evaluation was carried out according to the above steps. The results are shown in Table 3.

[0241] [Table 3]

[0242]

Claims

1. A method for manufacturing a recycled polycarbonate resin, which manufactures a recycled polycarbonate resin from a waste polycarbonate resin raw material, characterized in that the manufacturing method includes the following steps (S1) to (S4), Step (S1): A step of dissolving the waste polycarbonate resin raw material in a soluble good solvent to obtain a polycarbonate resin solution, Step (S2): A step of removing insolubles after bringing the polycarbonate resin solution into contact with a flocculant to obtain a solution (L) from which insolubles have been removed, Step (S3): A step of precipitating the recycled polycarbonate resin by mixing the solution (L) with a poor solvent, Step (S4): A step of recovering the precipitated recycled polycarbonate resin.

2. The method for manufacturing a regenerated polycarbonate resin according to claim 1, comprising: A step of bringing the polycarbonate resin solution into contact with a filter aid before removing insolubles in the step (S2).

3. The method for manufacturing a recycled polycarbonate resin according to claim 1 or 2, wherein the waste polycarbonate resin raw material contains 5% by mass or more in total of one or more polycarbonate resin compositions equivalent to those selected from the group consisting of the following (i) to (iii), and the waste polycarbonate resin raw material contains 10% by mass or more of polycarbonate resin, (i) A polycarbonate resin composition having a transmittance at 500 nm of 90% or less when measuring the transmittance of a solution obtained by dissolving it in dichloromethane to a concentration of 10% by mass using a 50 mm sample cell, (ii) A polycarbonate resin composition having a nitrogen atom content of 50 ppm by mass or more, (iii) A polycarbonate resin composition having a phosphorus atom content of 5 ppm by mass or more.

4. The method for manufacturing a recycled polycarbonate resin according to claim 1 or 2, wherein the good solvent used in the step (S1) contains a halogen-based solvent and / or a phenol-based solvent.

5. The method for manufacturing a recycled polycarbonate resin according to claim 1 or 2, wherein the poor solvent used in the step (S3) contains any one selected from the group consisting of a ketone-based solvent, a saturated hydrocarbon-based solvent, an alcohol-based solvent, and water.

6. The method for manufacturing a recycled polycarbonate resin according to claim 1 or 2, wherein the flocculant in the step (S2) is one or more selected from the group consisting of iron(III) chloride, iron(I) sulfate, iron(II) sulfate, aluminum chloride, aluminum sulfate, titanium oxide, copper(I) sulfate, copper(II) sulfate, copper(I) chloride, copper(II) chloride, zinc sulfate, an anionic polymer compound, a cationic polymer compound, and a nonionic polymer compound.

7. The method for manufacturing a recycled polycarbonate resin according to claim 6, wherein the flocculant in the step (S2) is one or more selected from the group consisting of iron(III) chloride, iron(II) sulfate, iron(III) sulfate, aluminum sulfate, aluminum chloride, polyacrylamide, and polyethylene oxide.

8. The method for manufacturing a recycled polycarbonate resin according to claim 2, wherein the filter aid is one or more selected from the group consisting of activated carbon, montmorillonite, diatomaceous earth, silica gel, and a synthetic adsorbent.

9. The method for producing a recycled polycarbonate resin according to claim 1 or 2, wherein the total content of Na, Mg, and Al in the recycled polycarbonate resin is 0.3 mass ppm or more and 20 mass ppm or less.

10. The method for producing a recycled polycarbonate resin according to claim 1 or 2, wherein the L value of the recycled polycarbonate resin based on reflectance measurement is 80 or more.

11. The method for producing a recycled polycarbonate resin according to claim 1 or 2, wherein the tensile nominal strain of the recycled polycarbonate resin is 60% or more.

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