KR100898899B1 - Method for preparing polycarbonate having improved thermal stability and good hydrolysis resistance and polycarbonate resin prepared thereby - Google Patents

Abstract

Method for producing a polycarbonate resin of the present invention is a method for producing a polycarbonate by transesterification of a diaryl carbonate and an aromatic dihydroxy compound in the presence of a catalyst consisting of an alkali, alkaline earth metal or a mixture thereof. It is characterized by improving the stability of the polycarbonate resin by adding a sulfonic acid ester compound of a specific structure to the carbonate.

Polycarbonate, Alkali metal, Catalyst deactivator, Thermal stability, Color stability, Hydrolysis resistance

Description

Method for preparing polycarbonate having improved thermal stability and good hydrolysis resistance and polycarbonate resin prepared thereby

Field of invention

The present invention relates to a method for producing polycarbonate and a polycarbonate resin prepared therefrom. More specifically, the present invention provides a method for preparing a polycarbonate having improved thermal stability, color stability and hydrolysis resistance by applying a specific sulfonic acid ester compound when preparing a polycarbonate using an alkali and / or alkaline earth metal catalyst, It relates to a polycarbonate resin.

Background of the Invention

Polycarbonate is excellent in mechanical properties such as impact resistance, and excellent in self-extinguishing, dimensional stability, heat resistance and transparency, the application range of electric and electronic product exterior materials, automotive parts, etc. are increasing day by day.

Generally, polycarbonate is prepared by interfacial polymerization by reacting a salt compound of dihydric phenol such as bisphenol A with phosgene in a liquid phase, or the dihydric phenol such as diphenyl carbonate is transesterified in a molten state. It is possible to avoid the use of highly toxic substances such as phosgene, to avoid the use of organic solvents such as methylene chloride, and to eliminate the need for a large amount of water. It is attracting attention as a friendly manufacturing process.

However, when the polycarbonate is prepared by the transesterification reaction, it is usually prepared using an alkali and / or alkaline earth metal catalyst. At this time, the alkali metal catalyst used in the reaction remains, so that the thermal stability or the color stability and the color stability of the polycarbonate are maintained. It becomes the cause of reducing hydrolysis property.

Japanese Patent Application No. 54-44303 discloses a method of preventing the molecular weight decrease of polycarbonate during molding by adding methyl benzene sulfonate or the like to a polycarbonate obtained through a polycondensation reaction using a sodium salt of bisphenol A as a catalyst. . However, the polycarbonate prepared by the above method has a disadvantage in that the initial color tone is poor, easily yellowed during melt molding, and inferior in heat resistance.

On the other hand, Japanese Patent No. 2924985 discloses a method of improving thermal stability, retention stability, and water resistance by using p-toluene sulfonic acid or butyl p-toluene sulfonate when producing polycarbonate. However, the method has some effects in terms of thermal stability and retention stability, but there is a disadvantage in that the hydrolysis property deteriorates when the amount is increased.

In order to solve the above problems, the present inventors have improved the thermal stability, color stability and hydrolysis resistance by applying a specific sulfonic acid ester compound and optionally a thio ester compound when preparing polycarbonate using an alkali and / or alkaline earth metal catalyst. It is to develop a method for producing a polycarbonate and a polycarbonate resin prepared therefrom.

An object of the present invention is to provide a method for producing a polycarbonate resin that can easily remove the alkali and / or alkaline earth metal catalyst by applying the existing equipment without modification or change of the reaction process.

Another object of the present invention is to provide a polycarbonate resin having improved hydrolysis resistance as well as thermal stability and color stability.

The above and other objects of the present invention can be achieved by the present invention described below.

Summary of the Invention

The present invention provides a method for producing a polycarbonate. The method comprises transesterifying a diaryl carbonate and an aromatic dihydroxy compound in the presence of a catalyst consisting of an alkali, alkaline earth metal or a mixture thereof to produce a polycarbonate; And it is characterized in that it comprises a step of removing the residual activity of the catalyst by adding a sulfonic acid ester compound or a mixture thereof represented by the formula (1) to the polycarbonate produced:

[Formula 1]

Wherein R ₁ and R ₃ are each a hydrocarbon group having 1 to 20 carbon atoms or a halogen substituted carbon group having 1 to 20 hydrocarbon groups, and may be the same as or different from each other, and R ₂ is a hydrocarbon group having 1 to 20 carbon atoms and a halogen substituted group. A hydrocarbon group having 1 to 20 carbon atoms or a glycol group having 1 to 20 carbon atoms and 1 to 10 oxygen atoms, and n is an integer of 0 to 5).

In one embodiment, R ₁ and R ₃ is an alkyl group having 1 to 20 carbon atoms, R ₂ is an alkyl group having 1 to 20 carbon atoms or a glycol group having 1 to 10 oxygen atoms, n may be an integer of 0 to 3 .

In another embodiment, the sulfonic acid ester compound is diethylene glycol di-p-tosylate, triethylene glycol di-p-tosylate, tetraethylene glycol With diethylene glycol di-p-tosylate, dipropylene glycol di-para-tosylate, tripropylene glycol di-para-tosylate, tetrapropylene glycol di-para-tosylate and mixtures thereof It may be selected from the group consisting of.

In the embodiment of the present invention, the sulfonic acid ester compound may be added at 0.1 to 10 ppm relative to the polycarbonate.

In one embodiment, the polycarbonate and the sulfonic acid ester compound produced by the transesterification may be extruded and mixed. The sulfonic acid ester compound may also be extruded with conventional additives.

In another embodiment of the present invention, the sulfonic acid ester compound may be used in combination with a thioester compound. The thioester compound can be added to more than 0 and 150 ppm or less.

In another aspect of the present invention relates to a polycarbonate resin produced by the above method. The polycarbonate resin may be present in the sulfonic acid ester compound or a mixture thereof 10 ppm or less, thioester compound 150 ppm or less.

In the specific example, the polycarbonate resin was measured for a 3 mm thick specimen formed by giving a cooling time of 5 minutes at 340 ° C. using a color difference meter (ND-1001 DP) manufactured by Nippon Denshoku Kogyo Co., Ltd. ΔYI) is 5.0 or less, and the molecular weight retention is 90% or more when the 3 mm specimens injected at the molding temperature of 290 ° C. and the mold temperature of 70 ° C. are kept at 90 ° C. and 95% relative humidity for 7 days.

Hereinafter, the content of the present invention will be described in detail below.

Detailed Description of the Invention

One aspect of the present invention is a method for producing a polycarbonate using an alkali and / or alkaline earth metal catalyst, by adding a sulfonic acid ester compound having a specific structure to the resulting polycarbonate, not only thermal stability and color stability but also hydrolysis resistance A method for producing an improved polycarbonate is disclosed.

In one embodiment the process comprises transesterifying a diaryl carbonate and an aromatic dihydroxy compound in the presence of a catalyst consisting of an alkali, an alkaline earth metal or a mixture thereof to produce a polycarbonate; And it is characterized in that it comprises the step of adding a sulfonic acid ester compound or a mixture thereof represented by the formula (1) to the polycarbonate produced:

[Formula 1]

Wherein R ₁ and R ₃ are each a hydrocarbon group having 1 to 20 carbon atoms or a halogen substituted carbon group having 1 to 20 hydrocarbon groups, and may be the same as or different from each other, and R ₂ is a hydrocarbon group having 1 to 20 carbon atoms and a halogen substituted group. A hydrocarbon group having 1 to 20 carbon atoms or a glycol group having 1 to 20 carbon atoms and 1 to 10 oxygen atoms, and n is an integer of 0 to 5).

The aromatic dihydroxy compound may be represented by the following formula (3).

[Formula 3]

(Wherein, A is a cycloalkylidene, -S- or -SO ₂ of a single bond, C ₁ -C ₅ alkylene, C ₁ -C ₅ alkylidene, C ₅ -C ₆ of the - denotes a).

Specific examples of the aromatic dihydroxy compound of Formula 3 include 4,4'-dihydroxydiphenyl, 2,2-bis- (4-hydroxyphenyl) -propane, 2,4-bis- (4-hydroxy Phenyl) -2-methylbutane, 1,1-bis- (4-hydroxyphenyl) -cyclohexane, 2,2-bis- (3-chloro-4-hydroxyphenyl) -propane, 2,2-bis -(3,5-dichloro-4-hydroxyphenyl) -propane, and the like, but are not necessarily limited thereto. Among them, 2,2-bis- (4-hydroxyphenyl) -propane, 2,2-bis- (3,5-dichloro-4-hydroxyphenyl) -propane, 1,1-bis- (4- Hydroxyphenyl) -cyclohexane and the like are preferred, and 2,2-bis- (4-hydroxyphenyl) -propane, also referred to as bisphenol-A, is most preferred.

Examples of the diaryl carbonate include diphenyl carbonate, ditoryl carbonate, bis (chlorophenyl) carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis (diphenyl) carbonate, diethyl carbonate, dimethyl carbonate, dibutyl carbonate, Dicyclohexyl carbonate etc. are mentioned, It is not necessarily limited to this. These may be used alone or in combination of two or more, preferably diphenyl carbonate.

In another embodiment of the present invention, by using the aromatic carbonate derivative compound represented by the following formula (4) mixed with the diaryl carbonate can further improve heat resistance and color stability. In the specific example, 60 to 95 mol% of the diaryl carbonate and 5 to 40 mol% of the aromatic carbonate derivative compound represented by the following Chemical Formula 3 may be mixed and used.

[Formula 4]

Wherein R ₁ is hydrogen, t-butyl group, p-cumyl group, R ₂ is t-butyl group, p-cumyl group.

The aromatic carbonate derivative compound may be added before the start of the transesterification reaction or in the transesterification reaction to proceed in situ.

In an embodiment of the present invention, the aromatic dihydroxy compound is used in a molar ratio of 0.7 to 1.5, preferably in a molar ratio of 0.8 to 1.2 with respect to the diaryl carbonate monomer. When used in the molar ratio, excellent mechanical strength can be obtained.

Examples of the alkali metal and alkaline earth metal catalysts used in the present invention include LiOH, NaOH, KOH, and the like, but are not necessarily limited thereto. These may be used alone or in combination of two or more thereof. The content of the catalyst can be determined by the amount of aromatic dihydroxy compound used. In one embodiment of the present invention, the aromatic dihydroxy compound per mol of about 1 × 10 ^-8 to 1 × 10 ^- it can be used in a range of ³ mol. In the above content range, by-products due to sufficient reactivity and side reactions may be minimized, thereby improving thermal stability and color stability.

In an embodiment of the present invention, the transesterification reaction may proceed under reduced pressure at 150 to 300 ℃, preferably 160 to 280 ℃, more preferably 190 to 260 ℃. It is preferable in the reaction rate and side reaction reduction in the above temperature range.

Further, the transesterification reaction is at least 10 minutes, preferably 15 minutes to 24 hours, more preferably 15 minutes to 75 torr or less under reduced pressure conditions of preferably 30 torr or less, more preferably 1 torr or less. Running for 12 hours is preferred for reducing reaction rate and side reactions.

In one embodiment of the present invention by reacting for about 2 to 9 hours at a reaction temperature of 160 ℃ to 260 ℃ to prepare a polycarbonate resin.

The sulfonic acid ester compound represented by Chemical Formula 1 or a mixture thereof is added to the polymer formed by the reaction to remove residual activity of the catalyst.

In one embodiment, the R ₁ and R ₃ is an alkyl group having 1 to 20 carbon atoms, R ₂ is an alkyl group having 1 to 20 carbon atoms or a glycol group having 1 to 10 oxygen atoms, n is an integer of 0 to 3 have.

In another embodiment, the sulfonic acid ester compound is diethylene glycol di-p-tosylate, triethylene glycol di-p-tosylate, tetraethylene glycol Diethylene glycol di-p-tosylate, dipropylene glycol di-para-tosylate, tripropylene glycol di-para-tosylate, tetrapropylene glycol di-para-tosylate and the like can be used. . These may be used alone or in combination of two or more thereof. Most preferably triethylene glycol di-para-tosylate.

In the embodiment of the present invention, the sulfonic acid ester compound may be added at 0.1 to 10 ppm, preferably 0.5 to 8 ppm, and most preferably 1 to 6 ppm with respect to the polycarbonate. When added over the above range, thermal stability or hydrolysis resistance may be lowered.

In the present invention, a thio ester compound represented by the following Chemical Formula 2 may be added together with the sulfonic acid ester compound:

 [Formula 2]

Wherein R ₁ , R _{2 ,} and R ₃ are each independently a hydrocarbon group having 1 to 12 carbon atoms or a halogen substituted hydrocarbon group having 1 to 12 carbon atoms, and n is an integer of 1 to 4).

Examples of the thio ester compound include tetrakis [methylene-3- (dodecylthio) propionate] methane and the like, but are not necessarily limited thereto. When used in combination with the thio ester compound, it is possible to further improve thermal stability and hydrolysis resistance.

The thio ester compound may be used at 150 ppm or less, preferably 10 to 130 ppm, more preferably 30 to 120 ppm, most preferably 50 to 100 ppm. If it exceeds the above range, thermal stability or color stability may be lowered.

In one embodiment, the sulfonic acid ester compound and optionally a thio ester compound may be added to the reactor as it is to the polycarbonate in which the reaction is completed, to prepare the in-situ reaction. In another embodiment, the polycarbonate and sulfonic acid ester compound produced by the transesterification reaction and optionally a thio ester compound may be mixed in the extrusion step. After the reaction of the polycarbonate produced after the reaction to the extruder, the sulfonic acid ester compound and optionally a thio ester compound may be added to the extruder to be produced in pellet form.

In addition, when the sulfonic acid ester compound and optionally a thio ester compound are added, they may be extruded together with conventional additives. The additives include flame retardants, antibacterial agents, mold release agents, heat stabilizers, antioxidants, light stabilizers, compatibilizers, dyes, inorganic additives, fillers, plasticizers, impact modifiers, admixtures, colorants, stabilizers, lubricants, antistatic agents, pigments, weathering agents, ultraviolet rays Blocking agents and the like may be used, but are not necessarily limited thereto. These may be used alone or in mixture of two or more.

In another aspect of the present invention relates to a polycarbonate resin produced by the above method. The polycarbonate resin may have a sulfonic acid ester compound or a mixture thereof of 10 ppm or less, preferably 5 ppm or less, more preferably 3 ppm or less. The more residual sulfonic acid ester compound in the final polycarbonate resin, the lower the thermal stability. The thioester compound may also be present at 150 ppm or less, preferably 100 ppm or less, more preferably 50 ppm or less.

In the specific example, the polycarbonate resin was measured for a 3 mm thick specimen formed by giving a cooling time of 5 minutes at 340 ° C. using a color difference meter (ND-1001 DP) manufactured by Nippon Denshoku Kogyo Co., Ltd. ΔYI) is 5.0 or less, and the molecular weight retention is 90% or more when the 3 mm specimens injected at the molding temperature of 290 ° C. and the mold temperature of 70 ° C. are kept at 90 ° C. and 95% relative humidity for 7 days.

The present invention provides a sulfonate ester compound of a specific structure and optionally a thio ester compound after the preparation of the polycarbonate resin without the need for further post-treatment, and thus the resins obtained by the alkali and / or alkaline earth metal catalysts remaining after use in the transesterification reaction. Deterioration can be suppressed. The polycarbonate resin prepared by the present invention can be applied to various products because the thermal stability and color stability as well as hydrolysis resistance can be significantly increased. For example, it can be used for automobiles, mechanical parts, electrical and electronic parts, office equipment such as computers, or miscellaneous goods. In particular, the present invention can be suitably applied to humidifiers, steam cleaners, steam irons, and the like, as well as housings of electric and electronic products such as televisions, computers, printers, washing machines, cassette players, audio, mobile phones, game machines, toys, and the like. As the molding method, a conventional method may be applied, and for example, extrusion molding, injection molding, vacuum molding, casting molding, extrusion molding, blow molding, calendar molding, or the like may be applied. These are well known by those skilled in the art to which the present invention belongs.

The invention can be better understood by the following examples, which are intended for purposes of illustration of the invention and are not intended to be limited or limited by the appended claims.

Example 1

180 Kg (788 mol) of 2,2-bis (4-hydroxyphenyl) propane (bisphenol A), 196 Kg (906 mol) of diphenylcarbonate, and 120 ppb of KOH (relative to 1 mol of BPA) were added to the reactor in that order. , Nitrogen was used to remove oxygen in the reactor. The temperature of the reactor was raised to 160 degrees to melt the raw material, and the temperature was raised to 190 degrees and maintained for 6 hours. After 6 hours, the reactor was heated up to 220 degrees, and the pressure was maintained at 70 Torr for 1 hour. The temperature was raised to 260 degrees and maintained at 20 torr for 1 hour, and then the pressure was lowered to 0.5 torr and maintained for 1 hour. The molecular weight of the produced polycarbonate is Mw 22.0 K. The resulting polycarbonate was transferred to a gear pump to the extruder, after which 1 ppm of triethylene glycol di-p-tosylate (TGDPP) and octadecyl 3- (3,5-di-tert) were extruded. -Butyl-4-hydroxyphenyl) propionate (Octadecyl3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) 150 ppm , 250 ppm of Tris (2,4-tert-butylphenyl) phosphite, 1000 ppm penta erythritol tetrastearte, pigment (solvent Violet 13 ) Pellets were prepared by adding 0.5 ppm.

The prepared polycarbonate pellets were dried at 120 ° C. for 4 hours, and then injected at a mold temperature of 290 ° C. and a mold temperature of 70 ° C. in a 10 OZ injection machine to prepare a specimen having a thickness of 3 mm. Molecular weight retention rate (%) was measured after staying for a day, and high temperature thermal stability evaluation was performed using an injection machine (DHC-180MC) manufactured by Dongshin Hydraulic Co., Ltd. at a molding temperature of 340 ° C and a mold temperature of 70 ° C. The yellowness (ΔYI) before and after the retention was measured using a colorimeter (ND-1001 DP) manufactured by Nippon Denshoku Kogyo Co., Ltd. for a 300 mm thick specimen. The degree of discoloration increases according to the number of moldings of the molded article. When the color difference (YI) of the three consecutive molded articles is 0.3 or less, the discoloration is regarded as stabilized, and the yellowness when the discoloration maintains a stable value is determined. It is measured. The measurement results are shown in Table 1 below.

Example 2

The same procedure as in Example 1 was conducted except that 3 ppm of triethylene glycol di-p-tosylate (TGGPP) was used.

Example 3

The same procedure as in Example 1 was conducted except that 5 ppm of triethylene glycol di-p-tosylate (TGGPP) was used.

Example 4

The same procedure as in Example 1 was carried out except that 10 ppm of triethylene glycol di-p-tosylate (TGGPP) was used.

Example 5

5 ppm Triethylene glycol di-p-tosylate (TGDPP) and tetrakis [methylene-3- (dodecylthio) propionate] methane (Tetrakis [methylene-3- (dodecylthio) Propionate] methane was carried out in the same manner as in Example 1 except for using 50 ppm.

Example 6

5 ppm Triethylene glycol di-p-tosylate (TGDPP) and tetrakis [methylene-3- (dodecylthio) propionate] methane (Tetrakis [methylene-3- (dodecylthio) Propionate] methane was carried out in the same manner as in Example 1 except that 100 ppm was used.

Comparative Example 1

Triethylene glycol di-para-tosylate (Triethylene glycol di- p-tosylate, TGDPP) was carried out in the same manner as in Example 1 except that.

Comparative Example 2

Triethylene glycol di-para-tosylate (Triethylene glycol di- p-tosylate, TGDPP) was carried out in the same manner as in Example 6 except that.

Comparative Example 3

Tetrakis [methylene-3- (dodecylthio) propionate] methane (Tetrakis [methylene-3- (dodecylthio) propionate] methane) was used in the same manner as in Comparative Example 2 except 200 ppm.

As shown in Table 1, when the sulfonic acid ester compound of the present invention is applied, it can be confirmed that the thermal stability, color stability and hydrolysis resistance are all excellent. In particular, in the case of Example 5-6 to which the sulfonic acid ester compound and the thio ester compound are applied, it can be seen that thermal stability, color stability, and hydrolysis resistance (molecular weight retention) are significantly improved. On the other hand, Comparative Example 1 without applying the sulfonic acid ester compound of the present invention can be seen that the thermal stability, color stability and hydrolysis resistance is significantly reduced, Comparative Example 1-2 applying the thio ester compound alone is It was confirmed that the hydrolysis resistance was improved, but there was no effect of improving the thermal stability.

The present invention is to apply the existing equipment without modification or change of the reaction process by removing the residual activity of the catalyst by applying a specific sulfonic acid ester compound and optionally a thio ester compound in the production of polycarbonate using an alkali and / or alkaline earth metal catalyst Not only can it easily remove alkali and / or alkaline earth metal catalysts, but it also improves thermal stability and color stability at high temperatures during molding and improves hydrolysis resistance. Has the effect of the invention to provide a polycarbonate resin and its production method applicable to the molded article.

Simple modifications or changes of the present invention can be easily carried out by those skilled in the art, and all such modifications or changes can be seen to be included in the scope of the present invention.

Claims (11)

A polycarbonate is prepared by transesterifying the diaryl carbonate and the aromatic dihydroxy compound in the presence of a catalyst consisting of an alkali, alkaline earth metal or a mixture thereof; And Injecting a sulfonic acid ester compound represented by the following formula (1) or a mixture thereof to the produced polycarbonate to remove the residual activity of the catalyst; Method for producing a polycarbonate resin, characterized in that it comprises a step: [Formula 1]

Wherein R ₁ and R ₃ are each a hydrocarbon group having 1 to 20 carbon atoms or a halogen substituted carbon group having 1 to 20 hydrocarbon groups, and may be the same as or different from each other, and R ₂ is a hydrocarbon group having 1 to 20 carbon atoms and a halogen substituted carbon number A hydrocarbon group having 1 to 20 or a glycol group having 1 to 20 carbon atoms and 1 to 10 oxygen atoms, and n is an integer of 0 to 5; The method according to claim 1, wherein R ₁ and R ₃ is an alkyl group having 1 to 20 carbon atoms, R ₂ is an alkyl group having 1 to 20 carbon atoms or a glycol group having 1 to 10 oxygen atoms, n is an integer of 0 to 3 The manufacturing method of polycarbonate resin made into. The method of claim 1, wherein the sulfonic acid ester compound is diethylene glycol di-p-tosylate, triethylene glycol di-p-tosylate, tetra Ethylene glycol di-p-tosylate, dipropylene glycol di-para-tosylate, tripropylene glycol di-para-tosylate, tetrapropylene glycol di-para-tosylate and their Method for producing a polycarbonate resin, characterized in that selected from the group consisting of a mixture. The method for producing a polycarbonate resin according to claim 1, wherein the sulfonic acid ester compound is added at 0.1 to 10 ppm with respect to the polycarbonate. The method for producing a polycarbonate resin according to claim 1, wherein the polycarbonate produced by the transesterification reaction and the sulfonic acid ester compound are extruded and mixed. The method of claim 5, wherein the sulfonic acid ester compound is a thioester compound, flame retardant, antibacterial agent, mold release agent, heat stabilizer, antioxidant, light stabilizer, compatibilizer, dye, inorganic additive, filler, plasticizer, impact modifier, admixture, colorant, stabilizer And a lubricant, an antistatic agent, a pigment, a weathering agent, a sunscreen and an additive selected from the group consisting of a mixture thereof. The method according to claim 6, wherein the thioester compound is represented by the following Chemical Formula 2: [Formula 2]

Wherein R ₁ , R _{2 ,} and R ₃ are each independently a hydrocarbon group having 1 to 12 carbon atoms or a halogen substituted hydrocarbon group having 1 to 12 carbon atoms, and n is an integer of 1 to 4). The method for producing a polycarbonate resin according to claim 7, wherein the thioester compound is added to more than 0 and 150 ppm or less. A polycarbonate resin prepared by the method of any one of claims 1 to 8, wherein the sulfonic acid ester compound or a mixture thereof is 10 ppm or less and the thioester compound is 150 ppm or less. According to claim 9, wherein the polycarbonate resin was measured on a 3 mm thick specimen molded with a cooling time of 5 minutes at 340 ℃ using a color difference meter (ND-1001 DP) manufactured by Nippon Denshoku Kogyo Co., Ltd. The degree of change (ΔYI) is 5.0 or less, and the molecular weight retention is 90% or more when a 3 mm specimen injected at a molding temperature of 290 ° C. and a mold temperature of 70 ° C. is kept at 90 ° C. and 95% relative humidity for 7 days. Polycarbonate resin. The color difference meter (ND-1001) manufactured by Nippon Denshoku Kogyo Co., Ltd., having a sulfonic acid ester compound represented by the following formula (1) or a mixture thereof 10 ppm or less, and a thioester compound represented by the following formula (2) being 150 ppm or less: The yellowness change (△ YI) measured on a 3 mm thick specimen formed by giving a cooling time of 5 minutes at 340 ° C. using a DP) was 5.0 or less, and a 3 mm specimen injected at a molding temperature of 290 ° C. and a mold temperature of 70 ° C. Polycarbonate resin, characterized in that the molecular weight retention rate is 90% or more when stayed at 90 ℃, 95% relative humidity for 7 days: [Formula 1]

Wherein R ₁ and R ₃ are each a hydrocarbon group having 1 to 20 carbon atoms or a halogen substituted carbon group having 1 to 20 hydrocarbon groups, and may be the same as or different from each other, and R ₂ is a hydrocarbon group having 1 to 20 carbon atoms and a halogen substituted carbon number A hydrocarbon group of 1 to 20 or a glycol group of 1 to 20 carbon atoms and 1 to 10 oxygen atoms, n is an integer of 0 to 5  [Formula 2]

Wherein R ₁ , R _{2 ,} and R ₃ are each independently a hydrocarbon group having 1 to 12 carbon atoms or a halogen substituted hydrocarbon group having 1 to 12 carbon atoms, and n is an integer of 1 to 4).