Method for adjusting color tone of polycarbonate resin composition, polycarbonate resin composition, and molded article thereof

Abstract

To provide a method for adjusting the color tone of a polycarbonate resin composition by which the variation of an a * value can be suppressed and a b * value can be adjusted to a desired value, and to provide a polycarbonate resin composition and a molded article thereof.SOLUTION: A method for adjusting a color tone of a polycarbonate resin composition, comprising blending a polycarbonate resin (A) with at least one bluing agent (B) having an effect of reducing an a * value and at least one bluing agent (C) having an effect of reducing a b * value to adjust the a * value and / or the b * value to a desired value, wherein a total content of the bluing agent (B) and the bluing agent (C) is 0.01 to 100 ppm by weight with respect to the polycarbonate resin (A).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for adjusting the color tone of a polycarbonate resin composition, a polycarbonate resin composition, and a molded article thereof. [Background technology]

[0002] Taking advantage of its advantages such as transparency, heat resistance, and mechanical strength, polycarbonate is widely used as a so-called engineering plastic in electrical and electronic parts, automotive parts, and the optical field such as optical recording media and lenses. However, although it is almost colorless and transparent, it has a slight yellowish tinge, which can give it an old or deteriorated appearance.

[0003] Therefore, a bluing agent is often added to counteract the yellowish color. For example, Patent Document 1 proposes a method of adding a blue to purple colorant to make the yellowish color less noticeable even when irradiated with ionizing radiation for sterilization. Patent Document 2 also proposes adding a bluing agent to counteract the yellowish color of molded products. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-207230 [Patent Document 2] Japanese Patent Application Laid-Open No. 2024-6996 Summary of the Invention [Problem to be solved by the invention]

[0005] However, by adding a bluing agent, * Value and a * The value was not controlled. When a large amount of bluing agent was added to color the bottle a deep blue, as in the case of a water bottle, the color turned out to be a purplish blue, and the intended blue color was not achieved.

[0006] Therefore, the present invention provides a * Suppress fluctuations in the value and * The present invention provides a method for adjusting the color tone of a polycarbonate resin composition, which can adjust the color tone of the polycarbonate resin composition to a desired value, a polycarbonate resin composition, and a molded article thereof. [Means for solving the problem]

[0007] As a result of extensive research into solving the above-mentioned problems, the present inventors have found that the addition of a bluing agent * At the same time as lowering the value, a * To prevent the value from changing and becoming unintended blue, * The inventors have found that the intended blue color can be obtained by adding a bluing agent whose value can be controlled, and have arrived at the present invention.

[0008] That is, the present invention is as follows. <1> Polycarbonate resin (A) * one or more bluing agents (B) that have the effect of reducing the value of b * It contains one or more bluing agents (C) that have the effect of reducing the value, a * value, and / or b * the total content of the bluing agent (B) and the bluing agent (C) is 0.01 to 100 ppm by weight relative to the polycarbonate resin (A). A method for adjusting the color tone of a polycarbonate resin composition. <2> The bluing agent (B) and the bluing agent (C) are each anthraquinone-based bluing agents. <1> 2. A method for adjusting the color tone of the polycarbonate resin composition according to claim 1. <3> The bluing agent (B) is Solvent Blue 97, and the bluing coloring agent (C) is one or more selected from Solvent Violet 13, Solvent Violet 36, and Solvent Red 52. <2> 2. A method for adjusting the color tone of the polycarbonate resin composition according to claim 1. <4> The method is characterized in that the blending amounts of the bluing agent (B) and the bluing agent (C) relative to the polycarbonate resin (A) are determined according to the following calculation formulas (1) and (2) so as to obtain a desired color tone. <3> 2. A method for adjusting the color tone of the polycarbonate resin composition according to claim 1. Adjusted a * Value = a of polycarbonate resin before blending with bluing agent * Value+ (0.11b+0.47C+1.17d)-0.39a (1) Adjusted b * Value = b of polycarbonate resin before blending with bluing agent * Value+ (-0.95b-0.66c-0.70d)-0.56a (2) (In the formula, a is the blending amount (ppm by weight) of Solvent Blue 97, b is the blending amount (ppm by weight) of Solvent Violet 13, c is the blending amount (ppm by weight) of Solvent Violet 36, and d is the blending amount (ppm by weight) of Solvent Red 52.) <5> The method is characterized in that the bluing agent (B) and the bluing agent (C) are blended with a polycarbonate resin in a molten state immediately after polymerization. <1> from <4> 2. A method for adjusting the color tone of a polycarbonate resin composition according to any one of claims 1 to 11. <6> The method is characterized in that the bluing agent (B) and the bluing agent (C) are blended with a polycarbonate resin in a solid state such as pellets or powder, and then melt-kneaded. <1> from <4> 2. A method for adjusting the color tone of a polycarbonate resin composition according to any one of claims 1 to 11. <7> The method is characterized in that a masterbatch is produced by melt-kneading the bluing agent (B) and the bluing agent (C) at a high concentration into a polycarbonate resin as a base material, and the masterbatch is blended with a solid polycarbonate resin such as pellets or powder, and then melt-kneaded. <1> from <4> 2. A method for adjusting the color tone of a polycarbonate resin composition according to any one of claims 1 to 11. <8> <1> from <7> 1. A polycarbonate resin composition obtained by the method for adjusting the color tone of a polycarbonate resin composition according to any one of claims 1 to 9. <9> <8> A molded article of the polycarbonate resin composition according to claim 1. [Effects of the Invention]

[0009] According to the present invention, * Suppress fluctuations in the value and * The present invention provides a method for adjusting the color tone of a polycarbonate resin composition, which can adjust the color tone of the polycarbonate resin composition to a desired value, a polycarbonate resin composition, and a molded article thereof. DETAILED DESCRIPTION OF THE INVENTION

[0010] The following describes in detail an embodiment of the present invention (hereinafter referred to as "the present embodiment"); however, the present invention is not limited to this embodiment, and various modifications are possible without departing from the spirit of the present invention.

[0011] [Method for adjusting color tone of polycarbonate resin composition] The method for adjusting the color tone of a polycarbonate resin composition according to this embodiment includes the steps of: Polycarbonate resin (A) * one or more bluing agents (B) that have the effect of reducing the value of b * It contains one or more bluing agents (C) that have the effect of reducing the value, a * value, and / or b *The total content of the bluing agent (B) and the bluing agent (C) is 0.01 to 100 ppm by weight relative to the polycarbonate resin (A).

[0012] (Polycarbonate resin) As the polycarbonate resin, a polycarbonate resin that can be used is generally produced by reacting a dihydroxy compound with a carbonate precursor by an interfacial polymerization method (solution method, phosgene method) or a melting method.

[0013] The dihydroxy compound may be a group consisting of a bisphenol compound, a dihydroxy compound represented by the following formula (A1), an alicyclic diol compound, and an aliphatic diol compound represented by the following formula (A2).

[0014] The bisphenol compound is not particularly limited, but examples thereof include 2,2-bis(4-hydroxyphenyl)propane (bisphenol-A), 1,1-bis(4-hydroxyphenyl)-1-phenylethane (bisphenol-AP), 2,2-bis(4-hydroxyphenyl)hexafluoropropane (bisphenol-AF), 2,2-bis(4-hydroxyphenyl)butane (bisphenol-B), bis(4-hydroxyphenyl)diphenylmethane (bisphenol-BP), 2,2-bis(3-methyl-4-hydroxyphenyl)propane (bisphenol-C), 1,1-bis(4-hydroxyphenyl)ethane (bisphenol-E), bis(4-hydroxyphenyl)methane (bisphenol-F), 5,5'-(1-methylethylidene)-bis[1,1'-(bisphenyl)-2-ol]propane (bisphenol-PH), and 1,1-bis(4-hydroxyphenyl)cyclohexane (bisphenol-Z). Bisphenol-A is preferred.

[0015] [ka] (In the formula, R1, R2, R3, and R4 each independently represent hydrogen, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a cycloalkyl group having 5 to 10 ring carbon atoms, a carbocyclic aromatic group having 5 to 10 ring carbon atoms, or a carbocyclic aralkyl group having 6 to 10 carbon atoms. In addition, one or more hydrogen atoms in R1, R2, R3, and R4 may be substituted with a halogen atom, an alkyl group having 1 to 10 carbon atoms, an alkoxy group having 1 to 10 carbon atoms, a phenyl group, a phenoxy group, a vinyl group, a cyano group, an ester group, an amide group, or a nitro group.)

[0016] The dihydroxy compound represented by the formula (A1) is preferably isosorbide, isomannide, or isoidide. Isosorbide, isomannide, and isoidide are stereoisomers. Among these dihydroxy compounds, isosorbide, which is obtained by dehydration condensation of sorbitol produced from various starches that are abundant and easily available as a plant-derived resource, is preferred in terms of availability and ease of production, colorability, thermal stability, mechanical properties, etc.

[0017] The alicyclic diol compound is preferably at least one selected from 1,4-cyclohexanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, and 1,4-cyclohexanedimethanol, more preferably at least one selected from the group consisting of 1,4-cyclohexanediol and 1,4-cyclohexanedimethanol, and particularly preferably 1,4-cyclohexanedimethanol. 1,4-Cyclohexanedimethanol exists as cis and trans isomers, and a mixture of cis and trans isomers may be used. The mixing ratio (mass ratio) is not particularly limited, but a mixture of 40 / 60 to 70 / 30, which is easily available, may be used.

[0018] HO-R 5 -OH (A2) (In the formula, R 5 represents an alkylene group having 2 to 12 carbon atoms. Examples of the aliphatic diol compound represented by the above formula (A2) include ethylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, and 1,6-hexanediol.

[0019] The resin may be a thermoplastic random-branched polycarbonate resin obtained by using a polyfunctional compound in combination with a dihydroxy compound.

[0020] Examples of carbonate precursors include carbonyl halides, haloformates, and carbonate esters, and specific examples include phosgene, dihaloformates of dihydric phenols, diphenyl carbonate, dimethyl carbonate, and diethyl carbonate. These may be bio-derived.

[0021] The reaction by the melting method is usually a transesterification reaction between a dihydroxy compound and diphenyl carbonate, in which the dihydroxy compound and diphenyl carbonate are mixed and reacted at 100 to 350°C under reduced pressure. The pressure is reduced stepwise, and finally to a range of 20 to 250 Pa, allowing the produced phenols to be removed from the system. The reaction time is about 2 to 5 hours.

[0022] The reaction using the interfacial polymerization method is usually a reaction between a dihydroxy compound and phosgene, and is carried out in the presence of an acid binder and an organic solvent. Examples of acid binders include alkali metal hydroxides such as sodium hydroxide and potassium hydroxide, and amine compounds such as pyridine. Examples of organic solvents include halogenated hydrocarbons such as methylene chloride and chlorobenzene. A catalyst such as a tertiary amine or a quaternary ammonium salt can also be used to promote the reaction. The reaction temperature is usually 0 to 50°C, and the reaction time is about 2 minutes to 5 hours.

[0023] <Bluing agent> The bluing agent may be any agent that is used in polycarbonate resins, such as azo-based colorants, indigo-based colorants, triphenylmethane-based colorants, and anthraquinone-based colorants, with anthraquinone-based colorants being easily available and therefore preferred.

[0024] Examples of anthraquinone-based bluing agents include those generally known as Solvent Blue 97 (such as Macrolex Blue RR manufactured by Lanxess), Solvent Violet 13 (such as Macrolex Violet B manufactured by Lanxess and Diaresin Blue G manufactured by Mitsubishi Chemical), Solvent Violet 36 (such as Macrolex Violet 3R manufactured by Lanxess), and Solvent Red 52 (such as Macrolex Red 5B manufactured by Lanxess). Of these, Solvent Blue 97 corresponds to the bluing agent (B). These bluing agents may be used alone or in combination of two or more.

[0025] a * As one or more bluing agents (B) having the effect of reducing the value, Solvent Blue 97 can be mentioned. b * The one or more bluing agents (C) having the effect of reducing the value include one or more selected from Solvent Violet 13, Solvent Violet 36, and Solvent Red 52.

[0026] It is preferable that the bluing agent (B) and the bluing agent (C) are each anthraquinone-based bluing agents.

[0027] To achieve a desired color tone, it is preferable to determine the amounts of the bluing agent (B) and the bluing agent (C) to be added to the polycarbonate resin (A) according to the following calculation formulas (1) and (2). Adjusted a * Value = a of polycarbonate resin before blending with bluing agent * Value+ (0.11b+0.47c+1.17d)-0.39a (1) Adjusted b * Value = b of polycarbonate resin before blending with bluing agent * Value+ (-0.95b-0.66c-0.70d)-0.56a (2) (In the formula, a is the blending amount (ppm by weight) of Solvent Blue 97, b is the blending amount (ppm by weight) of Solvent Violet 13, c is the blending amount (ppm by weight) of Solvent Violet 36, and d is the blending amount (ppm by weight) of Solvent Red 52.)

[0028] The blending amount of the bluing agent, in terms of the total content of the bluing agent (B) and the bluing agent (C), is 0.01 to 100 ppm by weight relative to 100% by weight of the polycarbonate resin (A).

[0029] The amount of the compound that produces an ice color is preferably 0.05 to 2.0 ppm by weight, more preferably 0.1 to 1.5 ppm by weight, and most preferably 0.2 to 1.0 ppm by weight. If the amount is less than 0.1 ppm by weight, the coloring is insufficient and the molded product will have a yellowish tinge, while if the amount is more than 2.0 ppm by weight, the molded product will have an excessively strong bluish tinge.

[0030] The blending amount to impart a deep blue color (for example, in a water bottle) is preferably 2.0 to 100 ppm by weight, more preferably 3.0 to 30 ppm by weight, and most preferably 5.0 to 20 ppm by weight. If the blending amount is around 2 ppm by weight, the blue coloring is insufficient, and if the blending amount exceeds 100 ppm by weight, the molded product will have an excessively strong blue tinge and will lose transparency.

[0031] <How to mix bluing agents> In the present embodiment, the method for blending the bluing agent is not particularly limited, and known methods can be used. For example, the polycarbonate resin and the bluing agent are premixed in a tumbler, Henschel mixer, or the like, and then melt-kneaded in an extruder to produce a pelletized polycarbonate resin composition. It is also preferable to blend the bluing agent with the additives described below to produce the polycarbonate resin composition.

[0032] More specifically, the method of blending the bluing agent is as follows: (i) Blending the bluing agent (B) and the bluing agent (C) into a molten polycarbonate resin immediately after polymerization. (ii) blending the bluing agent (B) and the bluing agent (C) with a polycarbonate resin in a solid state such as pellets or powder, followed by melt-kneading; or (iii) melt-kneading the bluing agent (B) and the bluing agent (C) at a high concentration into a polycarbonate resin as a base material to produce a masterbatch, blending the masterbatch with a solid polycarbonate resin such as pellets or powder, and then melt-kneading the blend; The method includes the steps of:

[0033] <Additives> Various additives can be added to the polycarbonate of this embodiment, thereby making it possible to produce polycarbonate resin compositions suitable for a variety of uses.

[0034] Examples of additives include heat stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, release agents, dyes and pigments, as well as flame retardants, catalyst deactivators, metal deactivators, antistatic agents, lubricants, nucleating agents, and the like.

[0035] Examples of heat stabilizers and antioxidants include, but are not limited to, phosphorus compounds, phenolic stabilizers, organic thioether stabilizers, and hindered amine stabilizers.

[0036] Examples of light stabilizers and ultraviolet absorbers include, but are not limited to, salicylic acid-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, benzotriazole-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers.

[0037] As the release agent, any known release agent can be used, and examples thereof include, but are not limited to, hydrocarbon-based release agents such as paraffins, aliphatic acid-based release agents such as stearic acid, fatty acid amide-based release agents such as stearic acid amide, alcohol-based release agents such as stearyl alcohol and pentaerythritol, aliphatic ester-based release agents such as glycerin monostearate, and silicone-based release agents such as silicone oil.

[0038] In addition, known materials that exhibit these properties can be used depending on the purpose as metal deactivators, antistatic agents, lubricants, lubricants, etc. These may be used alone or in combination of two or more.

[0039] <How to add additives> The method for adding an additive is not limited to the following, but examples thereof include a method of directly adding the additive at room temperature to a molten aromatic polycarbonate, a method of heating a substance that is solid at room temperature to its melting point or higher and adding it in a molten state, a method of adding the additive in the form of a solution using a predetermined solvent, and a method of adding the additive as masterbatch pellets.

[0040] When additives are added in a molten or solution state, a metering pump such as a plunger pump is preferably used as a supply device to the kneading apparatus. To prevent the molten aromatic polycarbonate from flowing back from the kneading apparatus into the piping for supplying the additives, the additive supply section of the kneading apparatus is generally equipped with an injection valve with a check function. However, when multiple supply sections are joined and connected to the injection valve, it is preferable to install a check valve in the piping between the metering pump and the kneading apparatus. A forced injection device such as a vane pump may also be installed between the metering pump and the kneading apparatus. It is preferable to control the temperature by heating to the melting point of the additives or above the melting point but below a temperature at which the additives do not deteriorate. When the additives are supplied in a solution state using a predetermined solvent, it is preferable to control the temperature to the melting point of the solution or above the melting point, or above a temperature at which the additives do not precipitate but below a temperature at which the additives do not deteriorate. The method of adding additives and the blowing agent in a molten state can reduce the thermal history required for melting, as compared to the method of blending them with solidified pellets, and is particularly useful for production by a melting method.

[0041] According to the method for adjusting the color tone of a polycarbonate resin composition according to the above-described embodiment, a polycarbonate resin composition can be obtained. * Suppress fluctuations in the value and * The value can be adjusted to a desired value. Furthermore, the polycarbonate resin composition can be used to produce molded products such as water bottles. [Example]

[0042] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to the following examples.

[0043] (Hue measurement) A test piece measuring 50 mm in length, 90 mm in width, and 3.0 mm in thickness was measured by the transmission method using a spectrophotometer (manufactured by Vista Hunter Lab) with a D65 light source and a viewing angle of 10°. * value and b * The values ​​were measured. a of the polycarbonate resin composition after blending the bluing agent * From the values, the a of the polycarbonate resin before blending the bluing agent * The value obtained by subtracting the value is Δa * The value was set as b of the polycarbonate resin composition after blending the bluing agent * From the values, the b value of the polycarbonate resin before blending the bluing agent * The value obtained by subtracting the value is Δb * The value was set as (CIE No.15 (ASTM E308) standard).

[0044] <Polycarbonate resin> A-1: Wonderlite PC-110K manufactured by Chimei Corporation (a polycarbonate resin made from bisphenol A using the melting method) A-2: Teijin Panlite L-1250WP (a polycarbonate resin made from bisphenol A using the interfacial polymerization method) A-3: Mitsubishi Chemical Corporation: Durabio D7340R (a polycarbonate resin made from isosorbide and 1,4-cyclohexanedimethanol). <Bluing agent> B-1: Solvent Blue 97 (Macrolex Blue RR manufactured by LANXESS) C-1: Solvent Violet 13 (Macrolex Violet B manufactured by Lanxess) <Bluing agent masterbatch> MBB-1: The raw materials were mixed in a tumbler at a ratio of A-2 / B-1 = 100 wt% / 25 wtppm, and melt-kneaded in a vented twin-screw extruder with a screw diameter of 30 mm at a barrel temperature of 280°C to obtain pellets. The obtained pellets were mixed in the tumbler for 5 minutes to obtain a bluing agent masterbatch. MBC-1: The raw materials were mixed in a tumbler at a ratio of A-2 / C-1 = 100 wt% / 25 wtppm, and melt-kneaded in a vented twin-screw extruder with a screw diameter of 30 mm at a barrel temperature of 280°C to obtain pellets. The obtained pellets were mixed in the tumbler for 5 minutes to obtain a bluing agent masterbatch.

[0045] [Examples 1 to 4, 6, Comparative Examples 1 to 4, Reference Examples 1 to 2] The raw materials were mixed in a tumbler in the proportions shown in Table 1, and melt-kneaded in a vented twin-screw extruder with a screw diameter of 30 mm at a barrel temperature of 280°C to obtain pellets. The resulting pellets were mixed in a tumbler for 5 minutes to prepare a polycarbonate resin composition for molding. (The reference example was also melt-kneaded in a twin-screw extruder to match the thermal history.) The pellets were dried in a hot air dryer at 120°C for 5 hours or more, and then continuously molded at a barrel temperature of 280°C and a mold temperature of 90°C to obtain test pieces measuring 50 mm long, 90 mm wide, and 3.0 mm thick. Table 1 shows the manufacturing conditions and measurement results.

[0046] [Example 5, Reference Example 3] The raw materials were mixed in a tumbler in the proportions shown in Table 1, and melt-kneaded in a vented twin-screw extruder with a screw diameter of 30 mm at a barrel temperature of 250°C to obtain pellets. The resulting pellets were mixed in a tumbler for 5 minutes to prepare a polycarbonate resin composition for molding. (The reference example was also melt-kneaded in a twin-screw extruder to match the thermal history.) The pellets were dried in a hot air dryer at 110°C for 5 hours or more, and then continuously molded at a barrel temperature of 250°C and a mold temperature of 70°C to obtain test pieces measuring 50 mm long, 90 mm wide, and 3.0 mm thick. Table 1 shows the manufacturing conditions and measurement results.

[0047] [Table 1]

[0048] [Examples 7 to 9, Reference Example 4] The raw materials were mixed in a tumbler in the proportions shown in Table 2 and dried in a hot air dryer at 120°C for at least 5 hours. Test pieces measuring 50 mm long, 90 mm wide, and 3.0 mm thick were then continuously molded at a barrel temperature of 280°C and a mold temperature of 90°C to obtain test pieces. Table 2 shows the manufacturing conditions and measurement results.

[0049] [Table 2] [Industrial Applicability]

[0050] In the bluing of polycarbonate resin, a * By adding a bluing agent that can control the value of a * Without changing the value of b * The value can be adjusted to the desired value.

Claims

1. The polycarbonate resin (A) contains a * one or more bluing agents (B) having the effect of reducing the value of b * One or more bluing agents (C) having the effect of reducing the value are blended, a * value, and / or b * the total content of the bluing agent (B) and the bluing agent (C) is 0.01 to 100 ppm by weight relative to the polycarbonate resin (A). A method for adjusting the color tone of a polycarbonate resin composition.

2. 2. The method for adjusting the color tone of a polycarbonate resin composition according to claim 1, wherein the bluing agent (B) and the bluing agent (C) are each anthraquinone-based bluing agents.

3. 3. The method for adjusting the color tone of a polycarbonate resin composition according to claim 2, wherein the bluing agent (B) is Solvent Blue 97, and the bluing colorant (C) is one or more selected from the group consisting of Solvent Violet 13, Solvent Violet 36, and Solvent Red 52.

4. 4. The method for adjusting the color tone of a polycarbonate resin composition according to claim 3, wherein the blending amounts of the bluing agent (B) and the bluing agent (C) relative to the polycarbonate resin (A) are determined according to the following calculation formulas (1) and (2) so as to obtain a desired color tone. After adjustment * Value = a of polycarbonate resin before blending with bluing agent * Value + (0.11b+0.47C+1.17d)-0.39a (1) Adjusted b * Value = b of polycarbonate resin before blending with bluing agent * Value + (-0.95b-0.66c-0.70d)-0.56a (2) (In the formula, a is the blending amount (ppm by weight) of Solvent Blue 97, b is the blending amount (ppm by weight) of Solvent Violet 13, c is the blending amount (ppm by weight) of Solvent Violet 36, and d is the blending amount (ppm by weight) of Solvent Red 52.)

5. 5. The method for adjusting the color tone of a polycarbonate resin composition according to claim 1, wherein the bluing agent (B) and the bluing agent (C) are blended with a polycarbonate resin in a molten state immediately after polymerization.

6. 5. The method for adjusting the color tone of a polycarbonate resin composition according to claim 1, wherein the bluing agent (B) and the bluing agent (C) are blended with a polycarbonate resin in a solid state such as pellets or powder, and then the blended mixture is melt-kneaded.

7. 5. The method for adjusting the color tone of a polycarbonate resin composition according to claim 1, wherein the bluing agent (B) and the bluing agent (C) are melt-kneaded at high concentrations into a polycarbonate resin serving as a base material to produce a masterbatch, and the masterbatch is blended with a polycarbonate resin in a solid state such as pellets or powder, followed by melt-kneading.

8. A polycarbonate resin composition obtained by the method for adjusting the color tone of a polycarbonate resin composition according to any one of claims 1 to 4.

9. A molded article made from the polycarbonate resin composition according to claim 8.

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