Method for producing purified polycarbonate resin

Abstract

According to the present invention, it is possible to provide a production method for producing a purified polycarbonate resin by removing an unreacted dihydroxy compound contained as an impurity in a polymerized polycarbonate resin, the production method comprising: (i) dissolving the polymerized polycarbonate resin in an organic solvent, and filtering to obtain a purified polycarbonate resin; (ii) a step for preparing a 1-30 mass% resin solution by an interfacial polymerization method, or (ii) a step for preparing a 1-30 mass% resin solution in which the polycarbonate resin after interfacial polymerization is dissolved in an organic solvent by an interfacial polymerization method; and a step for removing the unreacted dihydroxy compound contained as an impurity in the polymerized polycarbonate resin by introducing the obtained resin solution into column chromatography.

Description

Technical Field

[0001] The present invention relates to a method for producing a purified polycarbonate resin by effectively removing a dihydroxy compound as an impurity by a simple method. Background Art

[0002] Polycarbonate resins are used in a variety of applications due to their excellent properties. In polycarbonate resins, a dihydroxy compound (e.g., bisphenol) as a raw material is contained in a small amount as an impurity. A method for effectively removing such a dihydroxy compound as an impurity by a simple method is required.

[0003] For example, in Patent Document 1, as a method for providing a polycarbonate resin with less impurities, a method of extracting a granular polycarbonate resin with 2-ethoxyethyl acetate is proposed, but it is difficult to remove impurities present inside the granules.

[0004] In addition, in Patent Document 2, a method of reducing the content of volatile impurities by melt devolatilization of a polycarbonate resin containing volatile impurities is proposed. Although it may be effective for removing volatile impurities such as phenol, it is difficult to remove high-boiling compounds such as bisphenol.

[0005] Under such circumstances, a method is required that can industrially remove a dihydroxy compound as an impurity without deteriorating the polycarbonate resin, with low energy consumption and high efficiency.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: WO02 / 031024

[0009] Patent Document 2: JP 2009-52027 A Summary of the Invention

[0010] Problems to be Solved by the Invention

[0011] The subject of the present invention is to solve at least one of the above-mentioned existing problems. Furthermore, the subject of the present invention is to industrially remove a dihydroxy compound as an impurity without deteriorating the polycarbonate resin, with low energy consumption and high efficiency, and obtain a purified polycarbonate resin.

[0012] Means for Solving the Problems

[0013] The inventors of the present invention repeatedly conducted in-depth research to solve the existing problems, and as a result, found that by passing a specific resin solution through column chromatography, it is possible to industrially remove dihydroxy compounds as impurities without deteriorating the polycarbonate resin, with low energy consumption and high efficiency, and obtain a purified polycarbonate resin, thereby completing the present invention.

[0014] That is, the present invention includes the following aspects.

[0015] <1> A manufacturing method for producing a purified polycarbonate resin by removing unreacted dihydroxy compounds contained (accompanied) as impurities in the polymerized polycarbonate resin, comprising:

[0016] (i) a step of dissolving the above-mentioned polymerized polycarbonate resin in an organic solvent, filtering, and preparing a resin solution of 1 to 30% by mass, or (ii) a step of preparing a resin solution of 1 to 30% by mass in which the polycarbonate resin after interfacial polymerization is dissolved in an organic solvent by interfacial polymerization; and

[0017] A step of passing the obtained resin solution through column chromatography to remove unreacted dihydroxy compounds contained (accompanied) as impurities in the polymerized polycarbonate resin.

[0018] <2> The manufacturing method according to <1> above, wherein the above-mentioned column chromatography is simulated moving bed chromatography.

[0019] <3> The manufacturing method according to <1> or <2> above, wherein the above-mentioned organic solvent is dichloromethane.

[0020] <4> The manufacturing method according to any one of <1> to <3> above, wherein the above-mentioned dihydroxy compounds contained (accompanied) in the purified polycarbonate resin are 50 ppm or less.

[0021] <5> The manufacturing method according to any one of <1> to <4> above, wherein the above-mentioned polycarbonate resin is a bisphenol A type polycarbonate resin, and the above-mentioned dihydroxy compound is bisphenol A.

[0022] <6> A molded article comprising the purified polycarbonate resin obtained by the manufacturing method according to any one of <1> to <5> above.

[0023] Advantages of the Invention

[0024] According to the present invention, it is possible to industrially remove dihydroxy compounds as impurities without deteriorating the polycarbonate resin, with low energy consumption and high efficiency, and obtain a purified polycarbonate resin. Detailed Embodiments

[0025] Hereinafter, the present invention will be described in detail with reference to examples and the like. However, the present invention is not limited to the illustrated examples and the like, and can be changed to any method as long as it does not significantly deviate from the scope of the present invention.

[0026] One embodiment of the present invention is a method for manufacturing a purified polycarbonate resin by removing unreacted dihydroxy compounds contained (accompanied) as impurities in the polymerized polycarbonate resin, which includes: (i) dissolving the above-mentioned polymerized polycarbonate resin in an organic solvent, filtering, and preparing a resin solution of 1 to 30% by mass, or (ii) preparing a resin solution of 1 to 30% by mass in which the polycarbonate resin after interfacial polymerization is dissolved in an organic solvent by an interfacial polymerization method; and passing the obtained resin solution through a column chromatography to remove unreacted dihydroxy compounds contained (accompanied) as impurities in the polymerized polycarbonate resin.

[0027] In the present invention, as the organic solvent for dissolving the polymerized polycarbonate resin in the above-mentioned step (i) and the organic solvent for dissolving the polycarbonate resin after interfacial polymerization in the above-mentioned step (ii), dichloromethane, tetrahydrofuran, methyl ethyl ketone, acetone, methanol, ethanol, toluene, etc. can be cited, and dichloromethane is preferably included. These organic solvents can be used alone or in combination of two or more.

[0028] In the present invention, in the above-mentioned step (i), in order to remove components insoluble in the organic solvent, etc., filtration is carried out. It is preferably filtered using filter paper, membrane filters (mesh filters), metal filters which are metal filters using metal non-woven fabrics or wire meshes as filter media, various polymer filters such as leaf disk type, pleated type, candle type, laminated disk type, cylindrical type, etc., and more preferably filtered using a leaf disk type polymer filter with a large effective filtration area. The sieve holes of the above-mentioned polymer filter are preferably 500 μm or less, more preferably 100 μm or less, and particularly preferably 30 μm or less.

[0029] In the present invention, the concentration of the resin solution obtained after filtration in the above-mentioned step (i) and the resin solution obtained in the above-mentioned step (ii) is 1 to 30% by mass, preferably 5 to 20% by mass, and more preferably 10 to 20% by mass.

[0030] When the concentration of the above-mentioned resin solution is less than 1% by mass, the productivity of the polycarbonate resin deteriorates. When it exceeds 30% by mass, the viscosity of the resin solution rises sharply, and problems such as an increase in the internal pressure of the column chromatography or precipitation of the resin are likely to occur. In addition, the separation performance deteriorates.

[0031] In addition, when only considering the filtration process, it is advantageous that a lower concentration of the resin solution is easy to filter, while a higher concentration of the resin solution is not easy to filter, which is disadvantageous. The most suitable concentration can be determined taking into account both productivity and minimizing the solvent used.

[0032] In the present invention, the obtained resin solution is passed through a column chromatography to remove unreacted dihydroxy compounds contained (carried) as impurities in the polymerized polycarbonate resin. As the above-mentioned column chromatography, fixed bed chromatography, moving bed chromatography, multi-component separation circulation chromatography, simulated moving bed chromatography (alias: reverse phase chromatography), etc. can be used. From the viewpoint of good separation performance, being able to be scaled up, and being a system capable of recovering the solvent and being easily recycled, simulated moving bed chromatography is preferably used.

[0033] As the simulated moving bed chromatography preferably used in the present invention, it can be used without particular limitation, and the simulated moving bed chromatography described in Japanese Patent Laid-Open No. 11-228455 is preferably used.

[0034] The dihydroxy compound contained (carried) in the purified polycarbonate resin is preferably 50 ppm or less, more preferably 20 ppm or less, and particularly preferably 10 ppm or less.

[0035] In the present invention, as a method for measuring the concentration (ppm) of the dihydroxy compound in the resin, the method described in the following examples can be adopted.

[0036] According to the present invention, any type of polycarbonate resin can be purified. The polycarbonate resin to be purified is a bisphenol A type polycarbonate resin, which has a relatively stable structure, is technically easy to purify, is a type that is discharged in large quantities in society, and has a high importance for purification, so it is preferred. At this time, the dihydroxy compound to be removed is bisphenol A.

[0037] The purified polycarbonate resin obtained by such operation is preferably used for the manufacture of molded articles.

[0038] In addition, the present invention can also be applied to polycarbonate resins obtained from diols represented by the following general formula (2-1) or (2-2).

[0039]

[0040] (In general formula (2-1),

[0041] R c and R dindependently selected from a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, an aryl group having 6 to 20 carbon atoms which may have a substituent, a heteroaryl group having 6 to 20 carbon atoms which may have a substituent and contains one or more heteroatoms selected from O, N and S, an aryloxy group having 6 to 20 carbon atoms which may have a substituent, and -C≡C-R h3 ,

[0042] R h3 represents an aryl group having 6 to 20 carbon atoms which may have a substituent, or a heteroaryl group having 6 to 20 carbon atoms which may have a substituent and contains one or more heteroatoms selected from O, N and S,

[0043] Y1 represents a single bond or a fluorenyl group which may have a substituent,

[0044] C and D each independently represent an alkylene group having 1 to 5 carbon atoms which may have a substituent, p and q each independently represent an integer of 0 to 6,

[0045] c and d each independently represent an integer of 0 to 10.)

[0046]

[0047] (In the general formula (2-2),

[0048] R e and R f are each independently selected from a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, an alkoxy group having 1 to 20 carbon atoms which may have a substituent, a cycloalkyl group having 5 to 20 carbon atoms which may have a substituent, a cycloalkoxy group having 5 to 20 carbon atoms which may have a substituent, and an aryl group having 6 to 20 carbon atoms which may have a substituent,

[0049] Y2 is a single bond, a fluorenyl group which may have a substituent, or any one of the structural formulas shown in the following formulas (8) to (15),

[0050]

[0051] (In the formulas (8) to (15),

[0052] R 61 , R 62 , R 71 , R 72 , R 81 and R 82Each independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 20 carbon atoms which may have a substituent, or an aryl group having 6 to 30 carbon atoms which may have a substituent, or represents R 61 and R 62 、or R 71 and R 72 which are combined with each other to form a carbocyclic ring or heterocyclic ring having 1 to 20 carbon atoms which may have a substituent,

[0053] r and s each independently represent an integer of 0 to 5000.)

[0054] E and F each independently represent an alkylene group having 1 to 5 carbon atoms which may have a substituent, t and u each independently represent an integer of 0 to 4,

[0055] e and f each independently represent an integer of 0 to 10.)

[0056] Examples

[0057] Hereinafter, examples of the present invention will be illustrated to represent the content of the invention in detail, but the present invention is not limited to these examples.

[0058] <Dihydroxy compound concentration in resin (ppm)>

[0059] 1.2 g of a resin was dissolved in 7 ml of dichloromethane, and the resulting solution was added to 23 ml of acetone while stirring. A solid precipitated, and the supernatant was quantified by liquid chromatography. The analysis conditions of the liquid chromatography are as follows.

[0060] Apparatus: Alliance HPLCe2695 (manufactured by Waters)

[0061] Column: KF-801 (manufactured by Shodex) + KF-801 (manufactured by Shodex)

[0062] Detector: UV detector 2489 (manufactured by Waters)

[0063] Eluent: chloroform

[0064] Detection limit: 0.5 ppm

[0065] (Example 1)

[0066] A polycarbonate resin containing 90 ppm of bisphenol A was dissolved in dichloromethane and filtered through a disk-type polymer filter with a 20 μm pore size, whereby a 15% by mass polycarbonate resin solution was prepared. The resulting resin solution was passed through a simulated moving bed chromatography. By controlling the opening and closing of the solenoid valve using a sequence controller, the flow path was switched intermittently 8 times as one cycle, and fractionation was repeated.

[0067] The details of the simulated moving bed chromatography are described below.

[0068] Apparatus: Based on the simulated moving bed chromatography described in Japanese Patent Laid-Open No. 11-228455.

[0069] Column: Stainless steel column (with a heating jacket)

[0070] Inner diameter 0.9 cm, length 40 cm × 8 pieces, connected in series, porous gel filling temperature: 60 °C

[0071] Time for one cycle: 205 minutes

[0072] Supply flow rate: A total of 7.4 ml / min

[0073] Supply flow rate of the resin solution: 0.7 ml / min

[0074] Supply flow rate of the eluent: Dichloromethane, 6.7 ml / min

[0075] Withdrawal flow rate: A total of 7.4 ml / min

[0076] Weakly adsorbed fraction component: 2.8 ml / min

[0077] Strongly adsorbed fraction component: 4.6 ml / min

[0078] After the start of the fractionation operation, dichloromethane was evaporated from the solution collected from the weakly adsorbed fraction component 300 minutes to 350 minutes later, and a purified polycarbonate resin was obtained. Based on the above measurement method, the concentration of bisphenol A in the obtained purified polycarbonate resin was measured, and the result was 10 ppm.

[0079] (Example 2)

[0080] As the resin solution, a solution obtained by dissolving a polycarbonate resin obtained by an interfacial polymerization method in dichloromethane (15% by mass polycarbonate resin solution) was used. As a result of removing dichloromethane from this solution, the obtained polycarbonate resin contained 3 ppm of bisphenol A.

[0081] This solution was passed through a simulated moving bed chromatography. By controlling the opening and closing of the solenoid valve using a sequence controller, the flow path was switched intermittently 8 times as one cycle, and fractionation was repeated.

[0082] The details of the simulated moving bed chromatography are described below.

[0083] Simulated moving bed chromatography: Simulated moving bed type chromatography manufactured by ORGANO Corporation

[0084] Column: Stainless steel column (with a heating jacket)

[0085] Inner diameter 0.9 cm, length 40 cm × 8 pieces, connected in series, filled with porous gel Temperature: 55 °C

[0086] Time for one cycle: 220 minutes

[0087] Supply flow rate: Total 7.6 ml / min

[0088] Supply flow rate of resin solution: 0.8 ml / min

[0089] Supply flow rate of eluent: Dichloromethane, 6.8 ml / min

[0090] Withdrawal flow rate: Total 7.6 ml / min

[0091] Weakly adsorbed fraction component: 2.9 ml / min

[0092] Strongly adsorbed fraction component: 4.7 ml / min

[0093] After the fractionation operation starts, dichloromethane is evaporated from the solution collected from the weakly adsorbed fraction component 300 to 350 minutes later to obtain purified polycarbonate resin. Based on the above measurement method, the concentration of bisphenol A in the obtained purified polycarbonate resin was measured, and the result was 0.3 ppm.

Claims

1. A method for producing a purified polycarbonate resin by removing unreacted dihydroxy compounds contained as impurities in the aggregated polycarbonate resin, characterized in that, Comprising: (i) a step of dissolving the aggregated polycarbonate resin in an organic solvent, filtering, and preparing a resin solution having a concentration of 1 to 30% by mass; or (ii) a step of preparing, by an interfacial polymerization method, a resin solution having a concentration of 1 to 30% by mass, which is obtained by dissolving the interfacially polymerized polycarbonate resin in an organic solvent; and a step of passing the obtained resin solution through a column chromatography to remove unreacted dihydroxy compounds contained as impurities in the polymerized polycarbonate resin.

2. The production method according to claim 1, wherein: the column chromatography is a simulated moving bed chromatography.

3. The production method according to claim 1 or 2, wherein: the organic solvent is dichloromethane.

4. The production method according to any one of claims 1 to 3, wherein: the content of the dihydroxy compound in the purified polycarbonate resin is 50 ppm or less.

5. The production method according to any one of claims 1 to 4, wherein: the polycarbonate resin is a bisphenol A type polycarbonate resin, and the dihydroxy compound is bisphenol A.

6. A molded article, characterized in that: it contains a purified polycarbonate resin obtained by the production method according to any one of claims 1 to 5.

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