JP7644644B2 - Aromatic polycarbonate resin composition and molded article made thereof - Google Patents

Description

The present invention relates to an aromatic polycarbonate resin composition that is excellent in mold releasability and molding heat resistance and has a significantly reduced amount of volatile gas components by blending a required amount of a specific aliphatic ester compound. More specifically, the present invention relates to an aromatic polycarbonate resin composition that can be suitably used as a material for containers and covers used for storing or transporting various precision electronic materials such as magnetic disks or wafers processed into integrated circuit chips, and a molded article made of the same.

In resin containers for storing, transporting, and storing electronic components, electronic circuit boards, magnetic disks, semiconductor wafers, precision circuit boards such as mask glass, and other precision electronic materials, there has been a demand for reducing the amount of impurities that cause trace amounts of volatile gases in the molding materials (thermoplastic resin compositions). In response to this demand, Patent Document 1 proposes a polycarbonate resin that has fewer impurity chlorine atoms and impurity metal atoms and is more transparent and impact-resistant than other resins.

In recent years, as the diameter of semiconductor wafers has increased, the size of thin plate storage and transport containers has also increased. However, from the viewpoint of storage space, logistics costs, and raw material cost reduction, it is preferable to avoid making the containers larger than necessary, and the draft angle of the container is designed to be as small as possible. The larger the molded product and the smaller the draft angle, the greater the demolding load when the molded product is demolded. On the other hand, molded product structures have become more complex and precise in order to improve functionality, and some parts with small draft angles are unavoidable. For these reasons, there has been a trend in recent years to require materials with releasability, and a suitable material has been proposed in Patent Document 2. The material shown in Patent Document 2 is an aromatic polycarbonate resin composition for thin plate storage and transport containers that can reduce surface contamination of thin plates such as semiconductor wafers and magnetic disks, which are sensitive to surface contamination, and has excellent demolding properties during molding and excellent heat resistance during molding.

Furthermore, with the miniaturization of semiconductor components and the narrowing of wiring pitches, there is a strong demand for molding materials used in containers for semiconductor wafers (precision substrates) to reduce trace amounts of volatile matter detected in the material in order to prevent contamination of the wafers to a high degree. In order to meet this demand, the technology of Patent Document 2 requires a further reduction in trace amounts of volatile matter while maintaining a certain degree of releasability, and the selection of the aliphatic ester used as the release agent and the amount of the aliphatic ester to be used are important.

On the other hand, Patent Documents 3 and 4 are interesting in that they refer to the type of aliphatic esters to be blended into the polycarbonate resin and their characteristic values, but the amount of the aliphatic ester blended exceeds 0.2% by weight, and is not intended to significantly reduce trace volatile content. Patent Document 5 also limits the amount of aliphatic ester blended to the minimum necessary, but the aliphatic ester compounds restricted therein are similar to those shown in Patent Document 2, and are not effective in further reducing trace volatile content, and the maximum total amount of additives blended, including phosphorus-based antioxidants, exceeds 1% by weight.

Patent No. 3995346 Patent No. 5749335 Patent No. 5893856 Patent No. 5806008 Patent No. 6575979

The objective of the present invention is to provide an aromatic polycarbonate resin composition that has excellent mold releasability and molding heat resistance, and in which trace amounts of volatile gas components are highly reduced.

As a result of intensive research, the inventors discovered that the above object can be achieved by blending a small amount of a specific aliphatic ester compound, the characteristic values of which are regulated, in an aromatic polycarbonate resin composition, and by blending limited amounts of additives other than the aliphatic ester compound, and thus arrived at the present invention.

That is, according to the present invention, the following configurations (1) to (9) are provided.

(1) An aromatic polycarbonate resin composition comprising 100 parts by weight of (A) an aromatic polycarbonate resin (component A) and 0.01 to 0.12 parts by weight of (B) an aliphatic ester compound (component B) composed of a polyhydric alcohol and a higher fatty acid, wherein the total amount of the additives blended, including component B and additives other than component B, is 0.01 to 0.15 parts by weight, and the component B is
(i) the acid value is 5 or less;
(ii) the 5% weight loss temperature by TGA (thermogravimetric analysis) is 300° C. or higher;
1. An aromatic polycarbonate resin composition comprising:

(2) The aromatic polycarbonate resin composition according to the preceding paragraph 1, in which the viscosity average molecular weight of component A is in the range of 18,000 to 23,000.

(3) An aromatic polycarbonate resin composition according to the preceding paragraph 1 or 2, in which 0.015 to 0.07 parts by weight of component B is blended, and the total amount of blended additives, including component B and additives other than component B, is 0.015 to 0.10 parts by weight.

(4) An aromatic polycarbonate resin composition according to any one of items 1 to 3 above, in which the 5% weight loss temperature of component B by TGA (thermogravimetric analysis) is 330°C or higher.

(5) An aromatic polycarbonate resin composition according to any one of the preceding paragraphs 1 to 4, in which component B is an aliphatic ester compound whose main component is a full ester of pentaerythritol.

(6) An aromatic polycarbonate resin composition according to any one of items 1 to 5 above, in which the chlorine atom content in the aromatic polycarbonate resin composition is 5 ppm or less.

(7) A molded article molded from the aromatic polycarbonate resin composition described in any one of the preceding paragraphs 1 to 6.

(8) The molded product described in the preceding paragraph 7, which is a container for storing and transporting thin plates.

(9) The molded product according to paragraph 8 above, in which the thin plate storage and transport container is a storage and transport container for semiconductor wafers.

The polycarbonate resin composition of the present invention is an aromatic polycarbonate resin composition that has excellent mold releasability and molding heat resistance, and has a highly reduced amount of volatile gas components. It is useful for various industrial applications such as in the field of office automation equipment and the field of electrical and electronic equipment, and has exceptional industrial effects. For example, it is useful as exterior molded products and peripheral molded parts that cover electronic components, electronic substrates, magnetic disks, semiconductor wafers such as wafers processed into integrated circuit chips, precision substrates such as mask glasses, and other precision electronic materials, and as molded products and molded parts that constitute containers for storing, transporting, conveying, and storing the various electronic materials mentioned above.

The details of the present invention are described below.

<Component A: Aromatic polycarbonate resin>
The aromatic polycarbonate resin used in the present invention is obtained, for example, by reacting a dihydric phenol with a carbonate precursor by a solution method or a melting method. Representative examples of the dihydric phenol used here include 2,2-bis(4-hydroxyphenyl)propane (commonly known as bisphenol A), bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, bis(4-hydroxyphenyl)ether, 4,4-dihydroxydiphenyl, bis(4-hydroxyphenyl)sulfide, and bis(4-hydroxyphenyl)sulfone. The preferred dihydric phenol is a bis(4-hydroxyphenyl)alkane, and among these, bisphenol A is particularly preferred.

Carbonate precursors include carbonyl halides, carbonate esters, and haloformates, such as phosgene, diphenyl carbonate, and dihaloformates of dihydric phenols.

When the above dihydric phenol and carbonate precursor are reacted by a solution method or a melting method to produce an aromatic polycarbonate resin, the dihydric phenol may be used alone or in combination of two or more kinds, and a catalyst, a terminal terminator, an antioxidant for the dihydric phenol, etc. may be used as necessary. The aromatic polycarbonate resin may be a branched polycarbonate resin copolymerized with a polyfunctional aromatic compound having three or more functionalities, a polyester carbonate resin copolymerized with an aromatic or aliphatic, preferably an aromatic or aliphatic, bifunctional carboxylic acid having 8 or more carbon atoms, or a mixture of two or more aromatic polycarbonate resins.

In the present invention, the solution method is particularly suitable, and the reaction in the solution method is usually a reaction between a dihydric phenol and phosgene in the presence of an acid binder and an organic solvent. As the acid binder, for example, an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide, or an amine compound such as pyridine is used. As the organic solvent, for example, a halogenated hydrocarbon such as methylene chloride or chlorobenzene is used. In addition, a catalyst such as a tertiary amine or a quaternary ammonium salt can be used to promote the reaction. In this case, the reaction temperature is usually 0 to 40°C, and the reaction time is about several minutes to 5 hours.

In addition, in such a polymerization reaction, monofunctional phenols can be used as a terminal terminator. Monofunctional phenols are generally used as terminal terminators for molecular weight control, and the obtained polycarbonate resin has excellent thermal stability compared to those that are not, since the ends are blocked with groups based on monofunctional phenols. Such monofunctional phenols are generally phenol or lower alkyl-substituted phenols, and can be represented by the following formula (I).

(In the formula, R represents a hydrogen atom or an alkyl group having 1 to 9 carbon atoms, preferably 1 to 8 carbon atoms, and m represents an integer of 0 to 5, preferably 0 to 3.)

Specific examples of the monofunctional phenols include phenol, p-tert-butylphenol, p-cumylphenol, and isooctylphenol.

The reaction using the melting method is usually a transesterification reaction between a dihydric phenol and diphenyl carbonate, in which the dihydric phenol and diphenyl carbonate are mixed in the presence of an inert gas, and the reaction is usually carried out at reduced pressure, usually at 120 to 350°C, preferably using a polymerization catalyst such as an alkaline (earth) metal compound to accelerate the polymerization rate. The degree of vacuum is changed in stages, and finally reduced to 1 mmHg or less, and the phenols produced are removed from the system. The reaction time is usually about 1 to 4 hours.

The molecular weight of the aromatic polycarbonate resin used in the present invention is preferably in the range of 18,000 to 23,000 in terms of viscosity average molecular weight, more preferably 18,100 to 22,500, even more preferably 18,200 to 22,000, particularly preferably 18,300 to 21,000, and most preferably 18,400 to 20,000. Aromatic polycarbonate resins having such a viscosity average molecular weight are preferable because they have a certain mechanical strength and good flowability during molding. If the molecular weight is low, the molded product will not have enough strength, making it difficult to obtain a practical material. If the molecular weight is high, problems such as poor molding flowability are likely to occur, and further, problems such as phenolic compounds and chlorine-based organic solvents that cause trace volatile content detection are likely to remain in the resin. If the extrusion temperature is increased to solve this problem, the chlorine-based organic solvents will be reduced, but the resin may decompose and the amount of phenolic compounds may increase.

The viscosity average molecular weight (M) in the present invention is calculated by inserting the specific viscosity (η _SP ) determined from a solution in which 0.7 g of an aromatic polycarbonate resin is dissolved in 100 ml of methylene chloride at 20° C. into the following equation.
η _SP /c = [η] + 0.45 × [η] ² c (where [η] is the intrinsic viscosity)
[η]=1.23× ^10-4 M ^0.83
c=0.7

Specific viscosity can be measured, for example, as follows: First, polycarbonate resin is dissolved in methylene chloride in an amount 20 to 30 times its weight, and the soluble portion is collected by filtration through Celite. The solution is then removed and the mixture is thoroughly dried to obtain a solid that is soluble in methylene chloride. 0.7 g of this solid is dissolved in 100 ml of methylene chloride, and the specific viscosity at 20°C is determined using an Ostwald viscometer.

<Component B: Aliphatic Ester Compound>
The aromatic polycarbonate resin composition of the present invention comprises an aliphatic ester compound (B ) composed of a polyhydric alcohol and a higher fatty acid per 100 parts by weight of an aromatic polycarbonate resin.
Component) is blended in an amount of 0.01 to 0.12 parts by weight.

The amount of the aliphatic ester compound composed of a polyhydric alcohol and a higher fatty acid is preferably 0.01 to 0.10 parts by weight, more preferably 0.015 to 0.07 parts by weight, and even more preferably 0.02 to 0.05 parts by weight, per 100 parts by weight of the aromatic polycarbonate resin. If the amount of the aliphatic ester compound is less than the above range, the mold releasability during molding decreases, which is undesirable, and if the amount of the aliphatic ester compound is more than the above range, the heat resistance during molding decreases slightly, the aromatic polycarbonate resin becomes very slightly more likely to decompose, the amount of phenol compounds as trace volatile components increases, and the amount of trace volatile components detected in the aromatic polycarbonate resin composition increases due to the volatilization and decomposition of the aliphatic ester compound itself, which is undesirable.

It is essential that the type of aliphatic ester compound used in the present invention be selected so that it satisfies the following requirements: (i) the acid value is 5 or less, and (ii) the 5% weight loss temperature in TGA (thermogravimetric analysis) is 300°C or higher.

When two or more types of aliphatic ester compounds are blended, the "acid value" and "5% weight loss temperature in TGA (thermogravimetric analysis)" of component B shall be the weighted average of the values of each aliphatic ester compound.

When the acid value of the aliphatic ester compound is greater than 5, or the 5% weight loss temperature in TGA (thermogravimetric analysis) is less than 300°C, the contribution of the aliphatic ester compound itself to the aromatic polycarbonate increases, causing subtle decomposition of the aromatic polycarbonate resin and increasing the amount of trace volatile components that can be detected, or increasing the amount of trace volatile components that can be detected due to trace volatilization or trace decomposition of the aliphatic ester compound itself.

The acid value of the aliphatic ester compound is preferably 4.5 or less, more preferably 4 or less, and even more preferably 3.5 or less. The 5% weight loss temperature of the aliphatic ester compound in TGA (thermogravimetric analysis) is preferably 330°C or more, more preferably 350°C or more, and even more preferably 370°C or more.

The polyhydric alcohol constituting the aliphatic ester compound preferably has 3 to 32 carbon atoms. Specific examples of such polyhydric alcohols include glycerin, diglycerin, polyglycerin (e.g., decaglycerin, etc.), pentaerythritol, dipentaerythritol, diethylene glycol, and propylene glycol.

In addition, the higher fatty acid constituting the aliphatic ester compound is preferably an aliphatic carboxylic acid having 10 to 32 carbon atoms, and specific examples thereof include saturated aliphatic carboxylic acids such as decanoic acid, undecanoic acid, dodecanoic acid, tridecanoic acid, tetradecanoic acid, pentadecanoic acid, hexadecanoic acid (palmitic acid), heptadecanoic acid, octadecanoic acid (stearic acid), nonadecanoic acid, icosanoic acid, docosanoic acid, and hexacosanoic acid, as well as unsaturated aliphatic carboxylic acids such as palmitoleic acid, oleic acid, linoleic acid, linolenic acid, eicosenoic acid, eicosapentaenoic acid, and cetoleic acid. Among these, aliphatic carboxylic acids having 10 to 22 carbon atoms are more preferable, and those having 14 to 20 carbon atoms are even more preferable. Furthermore, saturated aliphatic carboxylic acids having 14 to 20 carbon atoms are preferable, and stearic acid and palmitic acid are particularly preferable. Aliphatic carboxylic acids such as stearic acid are usually in the form of mixtures containing other carboxylic acid components with different numbers of carbon atoms. Among the saturated fatty acid esters, ester compounds obtained from stearic acid or palmitic acid, which are produced from such natural fats and oils and are in the form of mixtures containing other carboxylic acid components, are preferably used.

Specific examples of the ester compounds that are preferably used include those containing glycerin monostearate, glycerin tristearate, and pentaerythritol tetrastearate as the main components.

<Content of specific components in aromatic polycarbonate resin composition>
The chlorine atom content in the aromatic polycarbonate resin composition of the present invention is preferably 30 ppm or less, more preferably 10 ppm or less, even more preferably 5 ppm or less, and particularly preferably 3 ppm or less, relative to the aromatic polycarbonate resin composition. Most of the chlorine atoms are those that remain in the aromatic polycarbonate resin from the chlorine-based organic solvent used in the polymer polymerization process, and in addition, they are derived from carbon tetrachloride contained as an impurity in the raw material phosgene and traces of unreacted chloroformate groups remaining in the polymer chain. If the amount of remaining chlorine-based organic solvent increases, the amount of trace volatile components detected from the resin will increase due to the volatilization and decomposition products of the chlorine-based organic solvent itself. The chlorine atom content in the aromatic polycarbonate resin composition of the present invention is measured by the combustion chlorine method.

The trace volatile components targeted for reduction in the present invention include the residual organic solvent components used in the above-mentioned polymer polymerization process, decomposition products of the residual organic solvent, additives blended during extrusion, such as volatile components and decomposition products from aliphatic ester compounds used as release agents, volatile components and decomposition products from phosphorus compounds used as stabilizers, and phenolic compounds derived from aromatic polycarbonate resins. Examples of phenolic compounds derived from aromatic polycarbonate resins include unreacted phenolic compounds remaining from the polymer polymerization of aromatic polycarbonate resins, and compounds resulting from the decomposition of aromatic polycarbonate resins during extrusion pelletization.

These phenolic compounds are phenolic compounds having 6 to 18 carbon atoms, and include monohydric phenolic compounds used for blocking ends in the production of aromatic polycarbonate resins, dihydric phenols as raw materials, and phenolic compounds that constitute additives. Phenol compounds having more than 18 carbon atoms have low volatility, so they have little impact on the achievement of the present invention.

Specific examples of phenol compounds having 6 to 18 carbon atoms include the aforementioned dihydric phenols, particularly bisphenol A, which are the raw materials, and the aforementioned monohydric phenols used as end terminators, such as phenol, p-tert-butylphenol, p-cumylphenol, and isooctylphenol.

In the aromatic polycarbonate resin composition of the present invention, it is important to suppress the amount of outgassing. Although it is also important to reduce the amount of solvents such as methylene chloride described above, it is particularly important to reduce volatile components such as additives other than methylene chloride and phenolic compounds, because the composition is suitable for use as a material for containers and covers used to store or transport various precision electronic materials.

The amount of outgassing in an aromatic polycarbonate resin composition, including methylene chloride, is preferably 500 ppb or less, and more preferably 300 ppb or less.

In addition, the amount of outgassing in the aromatic polycarbonate resin composition, including volatile components other than methylene chloride, is preferably 10 ppb or less, more preferably 7 ppb or less, and even more preferably 5 ppb or less.

The outgassing analysis (amount of methylene chloride component and other components) of the aromatic polycarbonate resin composition is performed by measuring the amount of gas components (methylene chloride and other components) generated when a sample is heated at 150° C. for 1 hour using an HS/GC/MS system that combines a headspace (HS) method and a gas chromatography/mass spectrometry (GC/MS).

<Method for reducing trace amounts of volatile components in aromatic polycarbonate resin composition>
The method for reducing the amount of volatile gas emitted from a resin composition according to the present invention is to "add a minimum amount of a specific aliphatic ester compound as an additive" when melt-extruding an aromatic polycarbonate resin powder granule alone or when melt-extruding an aromatic polycarbonate resin powder granule containing an additive.

In addition, as a method for reducing trace amounts of volatile gases from an aromatic polycarbonate resin composition, it is effective to further reduce the amount of chlorinated organic solvents and phenolic compounds having 6 to 18 carbon atoms remaining in the aromatic polycarbonate resin composition. For example, there are methods for enhancing drying of the aromatic polycarbonate resin in the latter stages of the polymer polymerization process, drying aromatic polycarbonate resin with an increased surface area, washing aromatic polycarbonate resin powder with a poor solvent, and enhancing devolatilization when melt extruding aromatic polycarbonate resin powder.

Specifically, an effective method for enhancing the drying of aromatic polycarbonate resin is to increase the drying temperature. However, it is not preferable to set the temperature above the softening point of the aromatic polycarbonate resin, and drying is usually carried out at 90 to 140°C. Other methods include extending the drying time and increasing the stirring efficiency of the aromatic polycarbonate resin during drying.

To increase the surface area of aromatic polycarbonate resin, it is preferable to make the particle size of the aromatic polycarbonate resin small and make it into a powder form, and for this purpose, methods such as strengthening the grinding of the aromatic polycarbonate resin are used. In particular, grinding dry resin is inefficient because the particles are too hard, so it is preferable to grind the resin in a slurry state containing organic solvent and water after granulation. It is also effective to make it into a porous powder. For example, there is a method of granulating by dropping an aromatic polycarbonate resin solution dissolved in a good solvent into a poor solvent set at a temperature significantly higher than the boiling point of the good solvent while stirring.

By using a method of washing aromatic polycarbonate resin, especially resin powder, with a poor solvent, the phenolic compounds in the aromatic polycarbonate resin are extracted into the poor solvent. Furthermore, this method also has the effect of replacing the chlorine-based organic solvent in the aromatic polycarbonate resin with the poor solvent, thereby reducing the amount of the chlorine-based organic solvent. Examples of poor solvents include acetone, methanol, and heptane, and of these, acetone is preferably used.

Specific methods for enhancing devolatilization when melt-extruding aromatic polycarbonate resin powder include increasing the devolatilization area in the melt extruder. Other methods include setting the devolatilization pressure low and using a devolatilization aid such as water.

Methods for reducing the amount of carbon tetrachloride in an aromatic polycarbonate resin composition include reducing the carbon tetrachloride concentration in the raw phosgene to reduce the amount of carbon tetrachloride carried over, specifically by adsorbing and removing carbon tetrachloride using activated carbon, or by separating and removing carbon tetrachloride from phosgene by distillation utilizing the boiling point difference between phosgene and carbon tetrachloride. In addition, a method for using methylene chloride with a low carbon tetrachloride content is to remove the carbon tetrachloride contained in the methylene chloride by distilling a part or all of the methylene chloride that is being recycled when the methylene chloride is recycled continuously.

Methods for reducing the number of chloroformate groups in aromatic polycarbonate resin include using a catalyst during polymerization, allowing sufficient polymerization time, and other methods to facilitate completion of the polymerization, as well as washing the aromatic polycarbonate resin with an alkaline aqueous solution such as an aqueous NaOH solution.

<Components other than component B (aliphatic ester compound)>
Various additives, other resins and fillers may be blended into the polycarbonate resin composition of the present invention as long as the effects of the present invention are not impaired. However, it is preferable not to use these or to use them in as small an amount as possible.

In the present invention, the total amount of additives to be blended, including component B and additives other than component B, is 0.01 to 0.15 parts by weight, preferably 0.01 to 0.13 parts by weight, more preferably 0.015 to 0.10 parts by weight, and even more preferably 0.02 to 0.08 parts by weight, relative to 100 parts by weight of aromatic polycarbonate resin. If it is within the above range, the mold releasability during molding is good, heat resistance during molding is excellent, and trace volatile components detected in the aromatic polycarbonate resin composition are suppressed, which is preferable.

In the aromatic polycarbonate resin composition of the present invention, while taking the above points into consideration, additives used for these improvements are advantageously used to improve the thermal stability, design, etc. of the composition. These additives are described in detail below.

[Heat stabilizer]
The heat stabilizer may be blended in a small amount to prevent deterioration of the resin and prevent a decrease in molecular weight or deterioration of the color during molding of the aromatic polycarbonate resin, within a range that does not impair the object of the present invention, and is preferably 0.001 to 0.03 parts by weight, more preferably 0.001 to 0.02 parts by weight, still more preferably 0.001 to 0.01 parts by weight, and particularly preferably 0.001 to 0.005 parts by weight, relative to 100 parts by weight of the aromatic polycarbonate resin. Within such a range, trace volatile components resulting from the volatilization of the heat stabilizer and the volatilization of decomposition products or altered products of the heat stabilizer are suppressed, which is preferable.

The aromatic polycarbonate resin composition of the present invention can be blended with a phosphorus-based heat stabilizer as a heat stabilizer.

Specific examples of such phosphorus-based heat stabilizers include phosphorous acid (phosphites), phosphonites, phosphinites, phosphines, phosphoric acids (phosphates), phosphonates, phosphinates, and phosphine oxides having aromatic or aliphatic groups, of which phosphites, phosphonites, phosphines, phosphonates, and phosphates are preferably used. Specific examples of the phosphite compound include trimethyl phosphite, triethyl phosphite, tripropyl phosphite, triisopropyl phosphite, tributyl phosphite, triphenyl phosphite, tris(nonylphenyl)phosphite, tridecyl phosphite, trioctyl phosphite, trioctadecyl phosphite, didecyl monophenyl phosphite, dioctyl monophenyl phosphite, diisopropyl monophenyl phosphite, monobutyl diphenyl phosphite, monodecyl diphenyl phosphite, monooctyl diphenyl phosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, tris(diethylphenyl)phosphite, tris(di-isopropylphenyl)phosphite, phenyl) phosphite, tris(di-n-butylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, tris(2,6-di-tert-butylphenyl) phosphite, distearyl pentaerythritol diphosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-ethylphenyl) pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite, bis(nonylphenyl) pentaerythritol diphosphite, dicyclohexyl pentaerythritol diphosphite, etc. Furthermore, as other phosphite compounds, those which react with dihydric phenols and have a cyclic structure can also be used. For example, 2,2'-methylenebis(4,6-di-tert-butylphenyl)(2,4-di-tert-butylphenyl)phosphite, 2,2'-methylenebis(4,6-di-tert-butylphenyl)(2-tert-butyl-4-methylphenyl)phosphite, 2,2'-methylenebis(4-methyl-6-tert-butylphenyl)(2-tert-butyl-4-methylphenyl)phosphite, 2,2'-ethylidenebis(4-methyl-6-tert-butylphenyl)(2-tert-butyl-4-methylphenyl)phosphite, etc. can be mentioned.

Phosphonite compounds include tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphonite, tetrakis(2,4-di-tert-butylphenyl)-4,3'-biphenylene diphosphonite, tetrakis(2,4-di-tert-butylphenyl)-3,3'-biphenylene diphosphonite, tetrakis(2,6-di-tert-butylphenyl)-4,4'-biphenylene diphosphonite, tetrakis(2,6-di-tert-butylphenyl)-4,3'-biphenylene diphosphonite, tetrakis(2,6-di-tert-butylphenyl)-3,3'-biphenylene diphosphonite, bis(2,4-di-tert-butylphenyl)-4-phenyl-phenylphosphonite, bis Examples of the phosphonite include (2,4-di-tert-butylphenyl)-3-phenyl-phenyl phosphonite, bis(2,6-di-n-butylphenyl)-3-phenyl-phenyl phosphonite, bis(2,6-di-tert-butylphenyl)-4-phenyl-phenyl phosphonite, and bis(2,6-di-tert-butylphenyl)-3-phenyl-phenyl phosphonite. Tetrakis(di-tert-butylphenyl)-biphenylene diphosphonite and bis(di-tert-butylphenyl)-phenyl-phenyl phosphonite are preferred, and tetrakis(2,4-di-tert-butylphenyl)-biphenylene diphosphonite and bis(2,4-di-tert-butylphenyl)-phenyl-phenyl phosphonite are more preferred. Such phosphonite compounds can be used in combination with the phosphite compounds having an aryl group substituted with two or more alkyl groups, and are therefore preferred.

Examples of phosphine compounds include triethylphosphine, tripropylphosphine, tributylphosphine, trioctylphosphine, triamylphosphine, dimethylphenylphosphine, dibutylphenylphosphine, diphenylmethylphosphine, diphenyloctylphosphine, triphenylphosphine, tri-p-tolylphosphine, trinaphthylphosphine, and diphenylbenzylphosphine. A particularly preferred phosphine compound is triphenylphosphine.

Examples of phosphonate compounds include dimethyl benzenephosphonate, diethyl benzenephosphonate, and dipropyl benzenephosphonate.

Examples of the phosphate compound include tributyl phosphate, trimethyl phosphate, tricresyl phosphate, triphenyl phosphate, trichlorophenyl phosphate, triethyl phosphate, diphenyl cresyl phosphate, diphenyl monoorthoxenyl phosphate, tributoxyethyl phosphate, dibutyl phosphate, dioctyl phosphate, diisopropyl phosphate, and the like, and preferably triphenyl phosphate and trimethyl phosphate.
Among these, tris(2,4-di-tert-butylphenyl)phosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphonite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, and bis(2,4-di-cumylphenyl)pentaerythritol diphosphite are preferred; bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite and tris(2,4-di-tert-butylphenyl)phosphite are more preferred; and tris(2,4-di-tert-butylphenyl)phosphite is particularly preferred.

[Hindered phenol-based antioxidants]
The aromatic polycarbonate resin composition of the present invention may contain a hindered phenol-based antioxidant within a range that does not impair the object of the present invention. The polycarbonate resin composition of the present disclosure has dry heat resistance such as little deterioration in color during molding processing or little discoloration of molded products during long-term use at high temperatures, but when further high dry heat resistance is to be imparted, it is effective to add such an antioxidant.

Examples of hindered phenol stabilizers include n-octadecyl-β-(4'-hydroxy-3',5'-di-tert-butylphenyl)propionate, 2,6-di-tert-butyl-4-(N,N-dimethylaminomethyl)phenol, 3,5-di-tert-butyl-4-hydroxybenzylphosphonate diethyl ester, 2,2'-methylenebis(4-methyl-6-tert-butylphenol), 2,2'-methylenebis(4-ethyl-6-tert-butylphenol), 4,4'-methylenebis(2,6-di-tert-butylphenol), 2,2'-methylenebis(4-methyl-6-cyclohexylphenol), 1,6-hexanediol bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], bis[2 4,4'-thiobis(3-methyl-6-tert-butylphenol), 2,2'-thiobis(4-methyl-6-tert-butylphenol), bis(3,5-di-tert-butyl-4-hydroxybenzyl)sulfide, 4,4'-di-thiobis(2,6-di-tert-butylphenol), 4,4'-tri-thiobis(2,6-di-tert-butylphenol), 2,2-thiodiethylenebis-[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], and tetrakis[methylene-3-(3',5'-di-tert-butyl-4-hydroxyphenyl)propionate]methane. All of these are commercially available. The above hindered phenol stabilizers can be used alone or in combination of two or more.

[Bluing agent]
In order to eliminate the yellowish color of the molded product, the aromatic polycarbonate resin composition of the present invention can be blended with a bluing agent within a range that does not impair the object of the present invention. There is no particular restriction on the bluing agent as long as it is used for polycarbonate resins. In general, anthraquinone dyes are preferred because they are easily available.

Specific examples of bluing agents include, for example, Solvent Violet 13 (CA. No. (Color Index No.) 60725; Trade Name: "Macrolex Violet B" manufactured by Bayer, "Diaresin Blue G" manufactured by Mitsubishi Chemical Corporation, and "Sumiplast Violet B" manufactured by Sumitomo Chemical Co., Ltd.), Solvent Violet 31 (CA. No. 68210; Trade Name: "Diaresin Violet D" manufactured by Mitsubishi Chemical Corporation), Solvent Violet 33 (CA. No. 60725; Trade Name: "Diaresin Blue J" manufactured by Mitsubishi Chemical Corporation), Solvent Blue 94 (CA. No. 61500; Trade Name: "Diaresin Blue N" manufactured by Mitsubishi Chemical Corporation), Solvent Violet 36 (CA. No. 68210; Trade Name: Representative examples include "Macrolex Violet 3R" manufactured by Bayer), Solvent Blue 97 (trade name "Macrolex Blue RR" manufactured by Bayer), and Solvent Blue 45 (CA. No. 61110; trade name "Polysynthren Blue RLS" manufactured by Clariant). Taking into account visual transmittance, etc., the bluing agent can be contained in the aromatic polycarbonate resin at a concentration of usually 0.3 to 1.2 ppm.

[Fluorescent whitening agents]
In the aromatic polycarbonate resin composition of the present invention, the fluorescent brightening agent can be used within a range that does not impair the object of the present invention, so long as it is used to improve the color tone of the resin or the like to white or bluish white. Examples of the fluorescent brightening agent include stilbene-based, benzimidazole-based, benzoxazole-based, naphthalimide-based, rhodamine-based, coumarin-based, and oxazine-based compounds. Specific examples of the fluorescent brightening agent include CI Fluorescent Brightener 219:1, Eastman Chemical Company's EASTOBRITE OB-1, and Hakkol Chemical Company's "Hakkol PSR." The fluorescent brightening agent has the effect of absorbing ultraviolet energy of light and radiating this energy in the visible region.

[Other heat stabilizers]
Other heat stabilizers that may be blended in the aromatic polycarbonate resin composition of the present invention include, for example, sulfur-based heat stabilizers. Examples of sulfur-based heat stabilizers include pentaerythritol-tetrakis(3-laurylthiopropionate), pentaerythritol-tetrakis(3-myristylthiopropionate), pentaerythritol-tetrakis(3-stearylthiopropionate), dilauryl-3,3'-thiodipropionate, dimyristyl-3,3'-thiodipropionate, and distearyl-3,3'-thiodipropionate. Among these, pentaerythritol-tetrakis(3-laurylthiopropionate), pentaerythritol-tetrakis(3-myristylthiopropionate), dilauryl-3,3'-thiodipropionate, and dimyristyl-3,3'-thiodipropionate are preferred. Particularly preferred is pentaerythritol-tetrakis(3-laurylthiopropionate). The thioether compound is commercially available from Sumitomo Chemical Co., Ltd. under the trade names Sumilizer TP-D (trade name) and Sumilizer TPM (trade name), and is therefore easily available.

[Other resins and elastomers]
The aromatic polycarbonate resin composition of the present invention may contain other resins or elastomers in an amount that does not impair the object of the present invention, that is, in an extremely small amount.

Examples of such other resins include polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyamide resins, polyimide resins, polyetherimide resins, polyurethane resins, polyphenylene ether resins, polyphenylene sulfide resins, polysulfone resins, polyolefin resins such as polyethylene and polypropylene, polystyrene resins, acrylonitrile/styrene copolymers (AS resins), acrylonitrile/butadiene/styrene copolymers (ABS resins), polymethacrylate resins, phenolic resins, and epoxy resins.

Examples of elastomers include isobutylene/isoprene rubber, styrene/butadiene rubber, ethylene/propylene rubber, acrylic elastomers, silicone rubber, polyester elastomers, polyamide elastomers, and core-shell elastomers such as MBS (methyl methacrylate/styrene/butadiene) rubber and MAS (methyl methacrylate/acrylonitrile/styrene) rubber.

[Ingredients other than those mentioned above]
In addition to the above, known additives may be blended into the resin composition of the present invention in order to impart various functions to the molded article or to improve the properties thereof, so long as the object of the present invention is not impaired.

<Production of polycarbonate resin composition>
Any method can be used to produce the polycarbonate resin composition of the present invention. For example, the A component, the B component, and any other components can be thoroughly mixed using a premixing means such as a V-type blender, a Henschel mixer, a mechanochemical device, or an extrusion mixer, and then granulated using an extrusion granulator or a briquetting machine, if necessary, and then melt-kneaded using a melt kneader, such as a vented twin-screw extruder, and pelletized using a pelletizer or other device. As an alternative method, the A component, the B component, and any other components can be independently supplied to a melt kneader, such as a vented twin-screw extruder, a method in which the A component and a part of the other components are premixed and then supplied to the melt kneader independently of the remaining components, a method in which the B component is diluted and mixed with water or an organic solvent, and then supplied to the melt kneader, or the diluted mixture is premixed with the other components, and then supplied to the melt kneader. If any of the components to be blended is liquid, a so-called liquid injection device or liquid addition device can be used to supply the components to the melt kneading extruder. It is also possible to use a device for injecting water as a devolatilizing aid into the melt kneading extruder.

<Molded products>
The aromatic polycarbonate resin composition can be molded into a molded article by a commonly known method such as injection molding, extrusion molding, compression molding, or the like, either as it is or after being pelletized in a melt extruder as described above.

Examples of molded products include molded products used for various industrial applications in the fields of office automation equipment and electrical and electronic equipment. Specific examples include molded products as exterior molded products or peripheral molded parts that cover electronic components, electronic substrates, magnetic disks, semiconductor wafers such as wafers processed into integrated circuit chips, precision substrates such as mask glass, and other precision electronic materials, as molded products as containers for storing, transporting, and storing the various electronic materials mentioned above, and molded products as molded parts that constitute containers. Among these, thin plate storage and transport containers used to store or transport various precision electronic materials such as magnetic disks or wafers processed into integrated circuit chips are preferred, and storage and transport containers for semiconductor wafers are particularly preferred.

The present invention will be described in detail below with reference to examples, but the present invention is not limited thereto. The aromatic polycarbonate resin powder obtained in each example, the characteristic values of the aliphatic ester compound used in each example, and the polycarbonate resin composition pellets obtained by melt extrusion were evaluated according to the following methods (1) to (5).

(1) Acid Value The acid value (KOH mg/g) was determined by neutralization titration method in accordance with JIS K 0070.

(2) 5% weight loss temperature by TGA (thermogravimetric analysis) Using Discovery SDT 650 manufactured by TA-instruments, the temperature was raised at 20°C/min in a _N2 atmosphere, and the temperature at which the weight loss of the sample reached 5% by weight of the charged weight was measured as the 5% weight loss temperature by TGA (thermogravimetric analysis).

(3) Viscosity Average Molecular Weight 0.7 g of aromatic polycarbonate resin powder was dissolved in 100 ml of methylene chloride, and the specific viscosity of the obtained solution was measured at 20° C. using an Ostwald viscometer. The viscosity average molecular weight (M) of the aromatic polycarbonate resin was calculated from the following formula.
Specific viscosity (η _SP )=(t−t ₀ )/t ₀
[ _t0 is the number of seconds that methylene chloride falls, and t is the number of seconds that the sample solution falls]
η _SP /c = [η] + 0.45 × [η] ² c (where [η] is the intrinsic viscosity)
[η]=1.23× ^10-4 M ^0.83
c=0.7

(4) Chlorine atom content The content was measured by the combustion chlorine method using a chlorine sulfur analyzer TOX-2100H manufactured by Nitto Seiko Analytech Co., Ltd. (formerly Mitsubishi Chemical Analytech). Specifically, the sample (pellet) was heated in an electric furnace (920°C) to completely vaporize it, and the vaporized gas was passed through sulfuric acid for dehydration, and then adsorbed into an electrolyte for chlorine (sodium acetate). The potential difference generated by the adsorption was returned to the original potential by potentiometric titration. The chlorine atom content was calculated from the energy required to return the potential to the original potential.

(5) Outgas Analysis The gas components (methylene chloride and other components) generated when 3 g of a sample (pellet) was heated at 150 for 1 hour were measured using an HS/GC/MS system that combines a headspace (HS) method using a 6890NGC & 5975B GC/MSD manufactured by Agilent Technologies, Inc. and a gas chromatography/mass spectrometry (GC/MS).

(6) Mold retention test In order to evaluate the mold retention stability, a mold retention test equivalent to the mold heat resistance test was carried out. The pellets obtained in each example were dried in a hot air dryer at 120°C for 5 hours, and molded into a three-stage plate having a width of 50 mm, a length of 90 mm, and a thickness of 3 mm (length 20 mm), 2 mm (length 45 mm), and 1 mm (length 25 mm) from the gate side using an injection molding machine J180ADS manufactured by Japan Steel Works, Ltd. at a cylinder temperature of 350°C, a mold temperature of 80°C, and a cycle of 1 minute. After 20 consecutive molding shots, the resin was retained in the cylinder of the injection molding machine at a cylinder temperature of 350°C for 10 minutes, and the hue (L*, a*, b*) of the 2 mm thick portion of the test piece before and after retention was measured in accordance with JIS K-7105 and JIS Z 8781-4 using a Color-Eye 7000A manufactured by X-Rite (formerly Gretag Macbeth) under conditions of light source D65, viewing angle 10 degrees, ^and transmission method in the ^CIE color system, and the color difference ΔE ^* was calculated according to the following formula (a ⁾ . The smaller the ^ΔE* , the better the molding retention stability.
ΔE ^* = {(ΔL ^* ) ² + (Δa ^* ) ² + (Δb ^* ) ² } ^1/2 ...Formula (a)
Color of "molded plate before retention": L ^* , a ^* , b ^*
Hue of "molded plate after retention": L ^* ', a ^* ', b ^* '
ΔL ^* :L ^* -L ^* '
Δa ^* : a ^* - a ^* '
Δb ^* :b ^* -b ^* '

(7) Demolding Load The pellets were dried at 120°C for 5 hours, and then injection molded using an injection molding machine (manufactured by The Japan Steel Works, Ltd.: J180ADS) at a cylinder temperature of 320°C and a mold temperature of 90°C using a cup-shaped mold for evaluating demolding properties (opening outer diameter: 70 mm, bottom outer diameter: 63 mm, height: 20 mm, thickness: 4 mm), and the ejection load at the time of demolding was measured using a load cell. The smaller this value, the better the demolding properties.

[Example 1]
A reactor equipped with a thermometer, a stirrer and a reflux condenser was charged with 2194 parts of ion-exchanged water and 402 parts of 48% aqueous sodium hydroxide solution, and 575 parts of 2,2-bis(4-hydroxyphenyl)propane and 1.2 parts of hydrosulfite were dissolved therein, and then 1810 parts of methylene chloride was added, and 283 parts of activated carbon-treated phosgene was blown in over 40 minutes at 15 to 25° C. with stirring. After the blowing in of phosgene was completed, 72 parts of 48% aqueous sodium hydroxide solution and 18.5 parts of p-tert-butylphenol were added, emulsified by stirring, and treated with a homomixer after 10 minutes, and then left unstirred at a temperature range of 30 to 33° C. for 3 hours to complete the reaction. After the reaction was completed, 1810 parts of methylene chloride was added, and the mixture was stirred and mixed for 20 minutes, and then allowed to stand, and the organic solvent solution phase of the polycarbonate resin and the aqueous phase were separated. Washing and separation were repeated three times by adding 1 part of ion-exchanged water to 1 part of the organic solvent solution of the separated polycarbonate resin until the conductivity of the aqueous phase became almost the same as that of the ion-exchanged water. The washed organic solvent solution of the polycarbonate resin was filtered through a SUS304 filter with a nominal filtration accuracy of 1 μm.

Next, the obtained polycarbonate resin organic solvent solution was poured into a kneader charged with 45°C hot water (an amount occupying about 10% of the kneader's internal space volume) over a period of 1 hour while stirring, and methylene chloride was evaporated and removed at an internal temperature of 45°C while blowing in steam to obtain a mixture of polycarbonate powder and water. This mixture of powder and water was passed through a grinder to be pulverized, and then poured into a hot water treatment tank equipped with an agitator whose water temperature was controlled at 95°C, where water was added to a mixture ratio of 25 parts powder and 75 parts water, and mixed with the agitator for 30 minutes. This mixture of powder and water was separated with a centrifuge to obtain a powder containing 3.5% by weight of methylene chloride and 10% by weight of water. Next, this powder was continuously fed at 50 kg/Hr (polycarbonate resin equivalent) to a SUS316L conductive heat receiving groove type two-axis agitator continuous dryer controlled at 140°C, and dried for an average drying time of 8 hours, yielding a powder with a viscosity average molecular weight of 18,500.

Next, 0.015 parts by weight of Unistar H-476-S (product name) (main component: pentaerythritol tetrastearate [acid value: 3.1, TGA 5% weight loss temperature: 378°C] manufactured by NOF Corp. was added to the obtained polycarbonate powder particles and stirred and mixed for 20 minutes using a Nauta mixer. The mixture was fed from the raw material feed port of a twin-screw extruder (TEX30α manufactured by Japan Steel Works, Ltd.) with two vents, an ion-exchanged water inlet between the vents, and a 20 μm disk-type screen between the cylinder and the die at 30 kg/Hr, and strands were melt-extruded under extrusion conditions of a screw rotation speed of 300 rpm, a resin temperature of 280°C, and a vent vacuum of 1 kPa. The melt-extruded strands were cooled in a cooling bath and then cut with a cutter to obtain pellets with a diameter of 3 mm and a length of 3 mm. In addition, 0.5 parts by weight of ion-exchanged water was supplied as a devolatilizing aid from the ion-exchanged water inlet per 100 parts by weight of the polycarbonate resin composition. The obtained pellets were subjected to the measurements and evaluations (4) to (7) above, and the results are shown in Table 1.

[Example 2]
A reactor equipped with a thermometer, a stirrer and a reflux condenser was charged with 2194 parts of ion-exchanged water and 402 parts of 48% aqueous sodium hydroxide solution, and 575 parts of 2,2-bis(4-hydroxyphenyl)propane and 1.2 parts of hydrosulfite were dissolved therein, and then 1810 parts of methylene chloride was added, and 283 parts of activated carbon-treated phosgene was blown in over 40 minutes at 15 to 25° C. with stirring. After the blowing in of phosgene was completed, 72 parts of 48% aqueous sodium hydroxide solution and 18.5 parts of p-tert-butylphenol were added, emulsified by stirring, and treated with a homomixer after 10 minutes, and then left unstirred at a temperature range of 30 to 33° C. for 3 hours to complete the reaction. After the reaction was completed, 1810 parts of methylene chloride was added, and the mixture was stirred and mixed for 20 minutes, and then allowed to stand, and the organic solvent solution phase of the polycarbonate resin and the aqueous phase were separated. Washing and separation were repeated three times by adding 1 part of ion-exchanged water to 1 part of the organic solvent solution of the separated polycarbonate resin until the conductivity of the aqueous phase became almost the same as that of the ion-exchanged water. The washed organic solvent solution of the polycarbonate resin was filtered through a SUS304 filter having a nominal filtration accuracy of 1 μm, and then tris(2,4-di-tert-butylphenyl)phosphite was added in an amount of 0.0025 parts by weight per 100 parts by weight of the polycarbonate resin.

Next, the obtained polycarbonate resin organic solvent solution was poured into a kneader charged with 45°C hot water (an amount occupying about 10% of the kneader's internal space volume) over a period of 1 hour while stirring, and methylene chloride was evaporated and removed at an internal temperature of 45°C while blowing in steam to obtain a mixture of polycarbonate powder and water. This mixture of powder and water was passed through a grinder to be pulverized, and then poured into a hot water treatment tank equipped with an agitator whose water temperature was controlled at 95°C, where water was added to a mixture ratio of 25 parts powder and 75 parts water, and mixed with the agitator for 30 minutes. This mixture of powder and water was separated with a centrifuge to obtain a powder containing 3.5% by weight of methylene chloride and 10% by weight of water. Next, this powder was continuously fed at 50 kg/Hr (polycarbonate resin equivalent) to a SUS316L conductive heat receiving groove type two-axis agitator continuous dryer controlled at 140°C, and dried for an average drying time of 8 hours to obtain polycarbonate resin powder with a viscosity average molecular weight of 18,500.

Next, 0.03 parts by weight of Unistar H-476-S (product name) (main component: pentaerythritol tetrastearate) manufactured by NOF Corp. was added to the obtained polycarbonate powder and mixed for 20 minutes using a Nauta mixer. The mixture was fed from the raw material feed port of a twin-screw extruder (TEX30α manufactured by Japan Steel Works, Ltd.) with two vents, an ion-exchanged water inlet between the vents, and a 20 μm disk-type screen between the cylinder and the die at 30 kg/Hr, and melt-extruded into strands under extrusion conditions of a screw rotation speed of 300 rpm, a resin temperature of 280°C, and a vent vacuum of 1 kPa. The melt-extruded strands were cooled in a cooling bath and then cut with a cutter to obtain pellets with a diameter of 3 mm and a length of 3 mm. In addition, 0.5 parts by weight of ion-exchanged water was supplied as a devolatilizing aid from the ion-exchanged water inlet per 100 parts by weight of the polycarbonate resin composition. The obtained pellets were subjected to the measurements and evaluations (4) to (7) above, and the results are shown in Table 1.

[Example 3]
Polycarbonate resin powder and pellets having a viscosity average molecular weight of 22,000 were obtained in the same manner as in Example 2, except that the amount of p-tert-butylphenol added was changed to 14.9 parts. The obtained pellets were subjected to the measurements and evaluations of (4) to (7) above, and the results are shown in Table 1.

[Example 4]
A reactor equipped with a thermometer, a stirrer and a reflux condenser was charged with 2194 parts of ion-exchanged water and 402 parts of 48% aqueous sodium hydroxide solution, and 575 parts of 2,2-bis(4-hydroxyphenyl)propane and 1.2 parts of hydrosulfite were dissolved therein, and then 1810 parts of methylene chloride was added, and 283 parts of activated carbon-treated phosgene was blown in over 40 minutes at 15 to 25° C. with stirring. After the blowing in of phosgene was completed, 72 parts of 48% aqueous sodium hydroxide solution and 18.5 parts of p-tert-butylphenol were added, emulsified by stirring, and treated with a homomixer after 10 minutes, and then left unstirred at a temperature range of 30 to 33° C. for 3 hours to complete the reaction. After the reaction was completed, 1810 parts of methylene chloride was added, and the mixture was stirred and mixed for 20 minutes, and then allowed to stand, and the organic solvent solution phase of the polycarbonate resin and the aqueous phase were separated. Washing and separation were repeated three times by adding 1 part of ion-exchanged water to 1 part of the organic solvent solution of the separated polycarbonate resin until the conductivity of the aqueous phase became almost the same as that of the ion-exchanged water. The washed organic solvent solution of the polycarbonate resin was filtered through a SUS304 filter having a nominal filtration accuracy of 1 μm, and then 4,4'-biphenylenediphosphinate tetrakis(2,4-di-tert-butylphenyl) was added in an amount of 0.0025 parts by weight per 100 parts by weight of the polycarbonate resin.

Next, the obtained polycarbonate resin organic solvent solution was poured into a kneader charged with 45°C hot water (an amount occupying about 10% of the internal space volume of the kneader) over a period of 1 hour while stirring.
While blowing in steam, methylene chloride was evaporated and removed at an internal temperature of 45°C to obtain a mixture of polycarbonate powder and water. The mixture of powder and water was passed through a grinder to grind it, and then charged into a hot water treatment tank equipped with an agitator whose water temperature was controlled at 95°C. Water was added to the mixture to give a mixing ratio of 25 parts powder and 75 parts water, and the mixture was mixed with the agitator for 30 minutes. The mixture of powder and water was separated by a centrifuge to obtain a powder containing 3.5% by weight of methylene chloride and 10% by weight of water. Next, the powder was continuously fed at 50 kg/Hr (polycarbonate resin equivalent) to a SUS316L conductive heat-receiving groove-type two-shaft agitator continuous dryer controlled at 140°C, and dried under the condition of an average drying time of 8 hours to obtain a polycarbonate resin powder having a viscosity average molecular weight of 18,500.

Next, 0.045 parts by weight of Unistar H-476-S (product name) (main component: pentaerythritol tetrastearate) manufactured by NOF Corp. was added to the obtained polycarbonate powder and mixed for 20 minutes using a Nauta mixer. The mixture was fed from the raw material feed port of a twin-screw extruder (TEX30α manufactured by Japan Steel Works, Ltd.) with two vents, an ion-exchanged water inlet between the vents, and a 20 μm disk-type screen between the cylinder and the die at 30 kg/Hr, and melt-extruded into strands under extrusion conditions of a screw rotation speed of 300 rpm, a resin temperature of 280°C, and a vent vacuum of 1 kPa. The melt-extruded strands were cooled in a cooling bath and then cut with a cutter to obtain pellets with a diameter of 3 mm and a length of 3 mm. In addition, 0.5 parts by weight of ion-exchanged water was supplied as a devolatilizing aid from the ion-exchanged water inlet per 100 parts by weight of the polycarbonate resin composition. The obtained pellets were subjected to the measurements and evaluations (4) to (7) above, and the results are shown in Table 1.

[Example 5]
The same procedure as in Example 1 was repeated except that the amount of Unistar H-476-S (trade name) manufactured by NOF Corp. added was changed to 0.1 parts by weight.

[Example 6]
The same procedure was carried out as in Example 2, except that 0.015 parts by weight of Roxiol VPG861 (product name) (main component: pentaerythritol tetrastearate [acid value: 1.0, TGA 5% weight loss temperature: 382° C.]) manufactured by Emery Oleochemicals Japan Ltd. was added per 100 parts by weight of polycarbonate resin, instead of adding 0.03 parts by weight of Unistar H-476-S (product name) manufactured by NOF Corp. per 100 parts by weight of polycarbonate resin. The obtained pellets were subjected to the measurements and evaluations of (4) to (7) above, and the results are shown in Table 1.

[Example 7]
The same procedure was carried out as in Example 1, except that 0.03 parts by weight of Roxiol VPG861 (product name) manufactured by Emery Oleochemicals Japan Ltd. was added per 100 parts by weight of polycarbonate resin, instead of 0.015 parts by weight of Unistar H-476-S (product name) manufactured by NOF Corp. added per 100 parts by weight of polycarbonate resin. The obtained pellets were subjected to the measurements and evaluations of (4) to (7) above, and the results are shown in Table 1.

[Example 8]
The same procedure was carried out as in Example 1, except that 0.045 parts by weight of Roxiol VPG861 (product name) manufactured by Emery Oleochemicals Japan Ltd. was added per 100 parts by weight of polycarbonate resin, instead of 0.015 parts by weight of Unistar H-476-S (product name) manufactured by NOF Corp. per 100 parts by weight of polycarbonate resin. The obtained pellets were subjected to the measurements and evaluations of (4) to (7) above, and the results are shown in Table 1.

[Example 9]
The same procedure was carried out as in Example 1, except that 0.1 part by weight of Roxiol VPG861 (product name) manufactured by Emery Oleochemicals Japan Ltd. was added per 100 parts by weight of polycarbonate resin, instead of 0.015 part by weight of Unistar H-476-S (product name) manufactured by NOF Corp., per 100 parts by weight of polycarbonate resin. The obtained pellets were subjected to the measurements and evaluations of (4) to (7) above, and the results are shown in Table 1.

[Example 10]
The same procedure was carried out as in Example 1, except that, instead of adding 0.015 parts by weight of Unistar H-476-S (trade name) manufactured by NOF Corp. to 100 parts by weight of polycarbonate resin, the amount of Unistar H-476-S (trade name) manufactured by NOF Corp. was changed to 0.04 parts by weight, and 0.01 parts by weight of Rikestar EW400 (trade name) manufactured by Riken Vitamin Co., Ltd. (main component: pentaerythritol tetrastearate [acid value: 10, TGA 5% weight loss temperature: 322° C.]) was further added. The obtained pellets were subjected to the measurements and evaluations in (4) to (7) above, and the results are shown in Table 1.

[Example 11]
The same procedure was carried out as in Example 1, except that, instead of adding 0.015 parts by weight of Unistar H-476-S (trade name) manufactured by NOF Corp. to 100 parts by weight of polycarbonate resin, the amount of Unistar H-476-S (trade name) manufactured by NOF Corp. was changed to 0.01 parts by weight, and 0.04 parts by weight of Rikemal S-100A (trade name) manufactured by Riken Vitamin Co., Ltd. (main component: glycerin monostearate [acid value: 2.0, TGA 5% weight loss temperature: 290°C]) was added. The obtained pellets were subjected to the measurements and evaluations in (4) to (7) above, and the results are shown in Table 1.

[Example 12]
The same procedure was carried out as in Example 3, except that ion-exchanged water (devolatilizing aid) was not supplied during melt extrusion. The obtained pellets were subjected to the measurements and evaluations of (4) to (7) above, and the results are shown in Table 1.

[Example 13]
The same procedure was carried out as in Example 5, except that ion-exchanged water (devolatilizing aid) was not supplied during melt extrusion. The pellets obtained were subjected to the measurements and evaluations in the above items (4) to (7), and the results are shown in Table 1.

[Example 14]
The same procedure was carried out as in Example 4, except that an aromatic polycarbonate resin powder (Teijin Ltd.: Panlite (trademark) L-1225WX) having a viscosity average molecular weight of 19,700 obtained by polymerizing bisphenol A and phosgene by an interfacial polymerization method was used instead of the polycarbonate resin powder having a viscosity average molecular weight of 18,500 obtained in Example 4. The obtained pellets were subjected to the measurements and evaluations of (4) to (7) above, and the results are shown in Table 1.

[Comparative Example 1]
The same procedure was carried out as in Example 5, except that the amount of Unistar H-476-S (product name) manufactured by NOF Corp. added was changed to 0.15 parts by weight. The obtained pellets were subjected to the measurements and evaluations in (4) to (7) above, and the results are shown in Table 2.

[Comparative Example 2]
The same procedure was carried out as in Example 12, except that 0.03 parts by weight of Rikemal S-100A (trade name) manufactured by Riken Vitamin Co., Ltd. was added per 100 parts by weight of polycarbonate resin, instead of 0.03 parts by weight of Unistar H-476-S (trade name) manufactured by NOF Corp., per 100 parts by weight of polycarbonate resin. The pellets obtained were subjected to the measurements and evaluations in (4) to (7) above, and the results are shown in Table 2.

[Comparative Example 3]
The same procedure was carried out as in Example 13, except that 0.1 parts by weight of Rikemal S-100A (trade name) manufactured by Riken Vitamin Co., Ltd. was added per 100 parts by weight of polycarbonate resin, instead of 0.1 parts by weight of Unistar H-476-S (trade name) manufactured by NOF Corp., per 100 parts by weight of polycarbonate resin. The pellets obtained were subjected to the measurements and evaluations in (4) to (7) above, and the results are shown in Table 2.

[Comparative Example 4]
The same procedure was carried out as in Example 13, except that 0.03 parts by weight of Rikestar EW400 (product name) (main component: pentaerythritol tetrastearate [acid value: 10, TGA 5% weight loss temperature: 322° C.]) manufactured by Riken Vitamin Co., Ltd. was added to 100 parts by weight of polycarbonate resin, instead of adding 0.1 parts by weight of Unistar H-476-S (product name) manufactured by NOF Corp. to 100 parts by weight of polycarbonate resin. The obtained pellets were subjected to the measurements and evaluations of (4) to (7) above, and the results are shown in Table 2.

[Comparative Example 5]
The same procedure was carried out as in Example 5, except that 0.03 parts by weight of Likester EW400 (product name) manufactured by Riken Vitamin Co., Ltd. was added per 100 parts by weight of polycarbonate resin, instead of 0.1 parts by weight of Unistar H-476-S (product name) manufactured by NOF Corp. per 100 parts by weight of polycarbonate resin. The obtained pellets were subjected to the measurements and evaluations (4) to (7) above, and the results are shown in Table 2.

[Comparative Example 6]
The same procedure was carried out as in Example 13, except that 0.1 parts by weight of Likester EW400 (product name) manufactured by Riken Vitamin Co., Ltd. was added per 100 parts by weight of polycarbonate resin instead of 0.1 parts by weight of Unistar H-476-S (product name) manufactured by NOF Corp. per 100 parts by weight of polycarbonate resin. The obtained pellets were subjected to the measurements and evaluations in (4) to (7) above, and the results are shown in Table 2.

[Comparative Example 7]
The same procedure was carried out as in Example 5, except that the amount of Unistar H-476-S (product name) manufactured by NOF Corp. added was changed to 0.005 parts by weight. The obtained pellets were subjected to the measurements and evaluations in (4) to (7) above, and the results are shown in Table 2.

The polycarbonate resin composition of the present invention has excellent mold releasability and molding heat resistance, and further has a significantly reduced amount of volatile gases. Transparent molded products obtained from the polycarbonate resin composition are useful for various industrial applications such as office automation equipment and electrical and electronic equipment, and are particularly useful as containers for storing and transporting thin plates such as semiconductor wafers.

Claims (5)

(A) 0.01 to 0.12 parts by weight of a full ester of pentaerythritol (component B) is blended with 100 parts by weight of an aromatic polycarbonate resin (component A) , the total amount of blended additives including component B and additives other than component B is 0.01 to 0.15 parts by weight, and the viscosity average molecular weight of component A is in the range of 18,000 to 23,000,
The component B is
(i) the acid value is 5 or less;
(ii) the 5% weight loss temperature by TGA (thermogravimetric analysis) is 300° C. or higher;
A thin plate storage and transport container molded from an aromatic polycarbonate resin composition. 2. The thin plate storage and transport container according to claim 1 , wherein the B component is blended in an amount of 0.015 to 0.07 parts by weight, and the total amount of blended additives including the B component and additives other than the B component is 0.015 to 0.10 parts by weight. 3. The thin plate storage and transport container according to claim 1, wherein the component B has a 5% weight loss temperature of 330[deg.] C. or higher by TGA (thermogravimetric analysis). 4. The thin plate storage and transportation container according to claim 1 , wherein the aromatic polycarbonate resin composition has a chlorine atom content of 5 ppm or less. 5. The thin plate storing and transporting container according to claim 4, which is a container for storing and transporting semiconductor wafers.