JP6176066B2 - Polycarbonate resin composition - Google Patents

Description

  The present invention relates to a polycarbonate resin composition. More specifically, the present invention relates to a polycarbonate resin composition excellent in surface hardness, scratch resistance, thermal stability, hue, and mechanical strength.

  Polycarbonate resins are excellent in mechanical strength, electrical properties, transparency, and the like, and are widely used as engineering plastics in various fields such as the electrical / electronic equipment field and the automotive field. In recent years, in these fields of application, molding products have become thinner, smaller, and lighter, and further improvements in the performance of molding materials are required. Among them, the development of polycarbonate resins that are thin but have high hardness is desired. Some proposals have been made.

  For example, a method for producing a polycarbonate or copolycarbonate having an excellent surface hardness using an aromatic dihydroxy compound having a specific structure different from conventional bisphenol A such as bisphenol C (Patent Document 1, Patent Document 2), dimethylbisphenolcyclohexane A method of balancing fluidity and hardness by blending a type polycarbonate and a bisphenol A type polycarbonate is known (Patent Document 3).

In the production of a polycarbonate resin, a stabilizer may be contained in order to prevent a decrease in molecular weight or deterioration in transparency during molding or the like. For example, Patent Document 4 discloses an example in which a phosphate stabilizer is used as a stabilizer.
Patent Document 5 discloses a polycarbonate resin composition containing a bisphenol C-based aromatic dihydroxy compound as a structural unit. As a stabilizer that is optionally added, a phosphate-based stabilizer or a hindered phenol-based stabilizer is disclosed. Agents are disclosed.

JP-A-64-069625 Japanese Patent Laid-Open No. 08-183852 International Publication No. 2009/083933 Pamphlet Japanese Patent No. 4183340 JP 2013-64046 A

However, when using the bisphenols having the above-mentioned specific structure as the raw material monomer, it was found that the deterioration of hue and transparency during molding and extrusion cannot be sufficiently suppressed when the above-mentioned stabilizer is used. did.
Under such circumstances, the object of the present invention is to reduce the hue and transparency during molding, extrusion, etc. even when a polycarbonate resin having a structural unit derived from an aromatic dihydroxy compound having a specific structure is used as a raw material. An object of the present invention is to provide a polycarbonate resin composition that is suppressed and excellent in surface hardness, scratch resistance, thermal stability, hue, and mechanical strength.

  As a result of intensive studies to solve the above problems, the present inventor has found that the following inventions meet the above object, and have reached the present invention.

That is, the present invention relates to the following inventions.
[1] For 100 parts by mass of the polycarbonate resin (A) containing a structural unit derived from the aromatic dihydroxy compound represented by the following formula (1), 0.001 to 0.5 parts by mass of the phosphonite compound (B), and A polycarbonate resin composition containing 0.01 to 0.5 parts by mass of a hindered phenol heat stabilizer (C) having a melting point of 100 ° C. or lower.

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group.)

[2] The polycarbonate resin composition according to [1], wherein the phosphonite compound (B) is represented by the following formula (2).
(In the formula (2), R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group. Show.)

[3] The polycarbonate resin composition according to the above [1] or [2], wherein the content of the structural unit derived from the compound represented by the following formula (3) is 0.5 ppm or more and 30 ppm or less.
(In Formula (3), R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group.)
[4] The polycarbonate resin composition according to any one of [1] to [3], wherein the phosphonite compound (B) has a melting point of 100 ° C. or lower.
[5] The polycarbonate resin composition according to any one of [1] to [4], wherein the amount of terminal OH groups of the polycarbonate resin (A) is 100 ppm or more.
[6] Any one of [1] to [5], wherein the polycarbonate resin (A) is a polycarbonate resin obtained by a melt polymerization method of an aromatic dihydroxy compound represented by the formula (1) and diaryl carbonate. The polycarbonate resin composition as described.

  According to the present invention, there is provided a polycarbonate resin composition that suppresses deterioration of color tone and transparency during molding, extrusion, etc., and is excellent in surface hardness, scratch resistance, thermal stability, hue, and mechanical strength. The

  Hereinafter, the present invention will be described in detail with reference to examples and the like, but the present invention is not limited to the following examples and the like, and can be arbitrarily modified and implemented without departing from the gist of the present invention.

The present invention relates to 100 parts by mass of a polycarbonate resin (A) containing a structural unit derived from an aromatic dihydroxy compound represented by the following formula (1), 0.001 to 0.5 parts by mass of a phosphonite compound (B), And a polycarbonate resin composition containing 0.01 to 0.5 parts by mass of a hindered phenol heat stabilizer (C) having a melting point of 100 ° C. or lower.

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group.)

  Hereinafter, the components of the polycarbonate resin composition of the present invention will be described in detail.

[Polycarbonate resin (A)]
The polycarbonate resin (A) contained in the polycarbonate resin composition of the present invention contains a structural unit derived from the aromatic dihydroxy compound represented by the above formula (1).
In the formula (1), examples of the substituted or unsubstituted alkyl group having 1 to 20 carbon atoms of R ¹ and R ² include, for example, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, and n-butyl. Group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, sec-pentyl group, n-hexyl group, n-heptyl group, n-octyl group, etc., substituted or unsubstituted aryl Examples of the group include a phenyl group, a benzyl group, a tolyl group, a 4-methylphenyl group, and a naphthyl group.

Among these, R ¹ and R ² are preferably a hydrogen atom, a methyl group, an ethyl group, an n-propyl group, or a 4-methylphenyl group, and particularly preferably a hydrogen atom.

Examples of the compound represented by the formula (1) include the following formulas (1a) and (1b).

  Among these, bisphenol C represented by the formula (1a) (hereinafter sometimes referred to as “BPC”) is preferable because a good hue and surface hardness can be obtained.

In the polycarbonate resin, since the amount of terminal hydroxyl groups greatly affects the thermal stability, hydrolysis stability, color tone, etc., the amount of terminal OH groups in the polycarbonate resin (A) is usually preferably 100 ppm or more. Preferably, it is 200 ppm or more, more preferably 400 ppm or more, and most preferably 500 ppm or more. However, it is usually 2000 ppm or less, preferably 1800 ppm or less, more preferably 1200 ppm or less, and most preferably 1000 ppm or less. When the terminal hydroxyl group concentration of the polycarbonate resin (A) is excessively small, the initial hue at the time of molding tends to deteriorate. When the terminal hydroxyl group concentration is excessively large, the residence heat stability tends to decrease.
A specific method for obtaining the amount of terminal OH groups of the polycarbonate resin (A) will be described later in Examples.

  The polycarbonate resin (A) is a structural unit derived from a dihydroxy compound other than the structural unit derived from the compound represented by the above formula (1) (hereinafter referred to as “other structural unit”) as long as the object of the present invention is not impaired. May be included).

Examples of other structural units include dihydroxybenzenes such as 1,2-dihydroxybenzene, 1,3-dihydroxybenzene (ie, resorcinol), 1,4-dihydroxybenzene;

Dihydroxybiphenyls such as 2,5-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl;

2,2′-dihydroxy-1,1′-binaphthyl, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, , 7-dihydroxynaphthalene, dihydroxynaphthalene such as 2,7-dihydroxynaphthalene;

2,2′-dihydroxydiphenyl ether, 3,3′-dihydroxydiphenyl ether, 4,4′-dihydroxydiphenyl ether, 4,4′-dihydroxy-3,3′-dimethyldiphenyl ether, 1,4-bis (3-hydroxyphenoxy) Dihydroxy diaryl ethers such as benzene and 1,3-bis (4-hydroxyphenoxy) benzene;

2,2-bis (4-hydroxyphenyl) propane (ie, bisphenol A),
1,1-bis (4-hydroxyphenyl) propane,
2,2-bis (3-methoxy-4-hydroxyphenyl) propane,
2- (4-hydroxyphenyl) -2- (3-methoxy-4-hydroxyphenyl) propane,
1,1-bis (3-tert-butyl-4-hydroxyphenyl) propane,
2,2-bis (3-cyclohexyl-4-hydroxyphenyl) propane,
2- (4-hydroxyphenyl) -2- (3-cyclohexyl-4-hydroxyphenyl) propane,
α, α′-bis (4-hydroxyphenyl) -1,4-diisopropylbenzene,
1,3-bis [2- (4-hydroxyphenyl) -2-propyl] benzene,
Bis (4-hydroxyphenyl) methane,
Bis (4-hydroxyphenyl) cyclohexylmethane,
Bis (4-hydroxyphenyl) phenylmethane,
Bis (4-hydroxyphenyl) (4-propenylphenyl) methane,
Bis (4-hydroxyphenyl) diphenylmethane,
Bis (4-hydroxyphenyl) naphthylmethane,
1,1-bis (4-hydroxyphenyl) ethane,
1,2-bis (4-hydroxyphenyl) ethane,
1,1-bis (4-hydroxyphenyl) -1-phenylethane,
1,1-bis (4-hydroxyphenyl) -1-naphthylethane,
1,1-bis (4-hydroxyphenyl) butane,
2,2-bis (4-hydroxyphenyl) butane,
2,2-bis (4-hydroxyphenyl) pentane,
1,1-bis (4-hydroxyphenyl) hexane,
2,2-bis (4-hydroxyphenyl) hexane,
1,1-bis (4-hydroxyphenyl) octane,
2,2-bis (4-hydroxyphenyl) octane,
1-bis (4-hydroxyphenyl) hexane,
2-bis (4-hydroxyphenyl) hexane,
4,4-bis (4-hydroxyphenyl) heptane,
2,2-bis (4-hydroxyphenyl) nonane,
1,10-bis (4-hydroxyphenyl) decane,
1,1-bis (4-hydroxyphenyl) dodecane,
Bis (hydroxyaryl) alkanes such as;

1,1-bis (4-hydroxyphenyl) cyclopentane,
1,1-bis (4-hydroxyphenyl) cyclohexane,
1,4-bis (4-hydroxyphenyl) cyclohexane,
1,1-bis (4-hydroxyphenyl) -3,3-dimethylcyclohexane,
1,1-bis (4-hydroxyphenyl) -3,4-dimethylcyclohexane,
1,1-bis (4-hydroxyphenyl) -3,5-dimethylcyclohexane,
1,1-bis (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane,
1,1-bis (4-hydroxy-3,5-dimethylphenyl) -3,3,5-trimethylcyclohexane,
1,1-bis (4-hydroxyphenyl) -3-propyl-5-methylcyclohexane,
1,1-bis (4-hydroxyphenyl) -3-tert-butyl-cyclohexane,
1,1-bis (4-hydroxyphenyl) -3-tert-butyl-cyclohexane,
1,1-bis (4-hydroxyphenyl) -3-phenylcyclohexane,
1,1-bis (4-hydroxyphenyl) -4-phenylcyclohexane,
Bis (hydroxyaryl) cycloalkanes such as;

Cardostructure-containing bisphenols such as 9,9-bis (4-hydroxyphenyl) fluorene, 9,9-bis (4-hydroxy-3-methylphenyl) fluorene;

Dihydroxy diaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide;

Dihydroxydiaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide;

Dihydroxydiaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone;

Among other structural units, a structural unit derived from bisphenol A (hereinafter sometimes referred to as “BPA”) is preferred from the viewpoints of heat resistance and impact resistance.
The ratio of the other structural unit in polycarbonate resin (A) is about 5-50 mass parts with respect to 100 mass parts of structural units derived from the compound shown by Formula (1).

The polycarbonate resin (A) is added to 2,2-bis (4-hydroxyphenyl) propane (bisphenol A) as necessary, in addition to the polycarbonate resin contained in the structural unit derived from the compound represented by the formula (1). The polycarbonate resin which has the derived structural unit as a main component can be included.
The content of the polycarbonate resin (A) contained in the structural unit derived from the compound represented by the formula (1) is more preferably 10% by weight or more in the total polycarbonate resin, and further preferably 20% by weight or more, 30% by weight or more is most preferable. Moreover, 99 weight% or less is preferable and 90 weight% or less is more preferable. If the content of the polycarbonate resin contained in the structural unit derived from the compound represented by the formula (1) is too large, the impact resistance may be lowered, and if it is too small, the color tone may be deteriorated and the pencil hardness may be lowered. Is not preferable.

  The polycarbonate resin (A) preferably further contains a specific amount of a structural unit derived from a compound represented by the following formula (3). In the present invention, the amount of the structural unit derived from the compound represented by the formula (3) contained in the polycarbonate resin (A) of the present invention is determined by subjecting the polycarbonate resin (A) of the present invention to alkaline hydrolysis by the method described below. When decomposing, it is defined by the value measured by liquid chromatography.

(In Formula (3), R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group.)

  In the polycarbonate resin (A), the content in the case where the structural unit derived from the compound represented by the formula (3) is contained is preferably 0.5 ppm or more and 30 ppm or less, and more preferably 1 ppm or more and 27 ppm or less. More preferably, it is 2 ppm or more and 24 ppm or less. The content of the compound represented by the formula (3) has a great influence on the yellowness and brightness of the polycarbonate resin, and the content of the structural unit derived from the compound represented by the formula (3) is too large. In this case, yellowing is likely to cause a decrease in brightness.

-Compound represented by Formula (3) In the compound represented by Formula (3), R ¹ and R ² are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, Or a substituted or unsubstituted aryl group, which is the same as R ¹ and R ² shown in Formula (1).

  The compound represented by the formula (3) is presumed to be produced by heating the polymer raw material and contacting oxygen in the step of mixing the raw materials. In addition, the compound represented by the formula (3) does not directly deteriorate the color tone, but when the compound represented by the formula (3) is generated, a trace amount of a color-causing component is generated at the same time. It is guessed. Although the amount of the coloring component is very small, it is difficult to detect by a normal method. However, by adjusting the generation amount and residual amount of the compound represented by the formula (3), the color tone and brightness are improved. Can be made. The structure of the compound represented by the formula (3) is presumed to be a branch point in the polycarbonate resin from the structure. The structure represented by the compound represented by the formula (3) has not been observed in a polycarbonate using bisphenol A as a raw material, and is considered to be a structure peculiar to the polycarbonate resin of the present invention. For this reason, in order to reduce the amount of the compound represented by the formula (3), it is efficient to adjust the production conditions as described later.

-Determination method by alkali hydrolysis The amount of the structural unit derived from the compound represented by the formula (3) in the polycarbonate resin (A) is determined by liquid chromatography when the polycarbonate resin of the present invention is alkali-hydrolyzed. It is defined by the value measured at. As a measuring method, 0.5 g of polycarbonate resin was dissolved in 5 mL of methylene chloride, 45 mL of methanol and 5 mL of 25 wt% aqueous sodium hydroxide solution were added, and the solution obtained by stirring at 70 ° C. for 30 minutes was subjected to liquid chromatography. The amount of the structural unit derived from the compound represented by the formula (3) is quantified by graphic analysis.

The amount of the structural unit derived from the compound represented by the formula (3) by liquid chromatography can be measured, for example, under the following conditions.
(Analysis conditions)
Liquid chromatography device: System controller manufactured by Shimadzu Corporation: CBM-20A
Pump: LC-10AD
Column oven: CTO-10ASvp
Detector: SPD-M20A
Analytical column: YMC-Pack ODS-AM 75 mm × Φ4.6 mm
Oven temperature: 40 ° C
Detection wavelength: 280 nm
Eluent: A solution: 0.1% trifluoroacetic acid aqueous solution, B solution: acetonitrile A / B = 60/40 (vol%) to A / B = 95/5 (vol%) in 25 minutes Gradient flow rate: 1 mL / Min
Sample injection volume: 20 μL

  More specifically, taking the case where the compound represented by formula (1) is 2,2-bis (3-methyl-4-hydroxyphenyl) propane as an example, it is represented by formula (3). A compound which is a structural unit derived from a compound is observed at the following retention time under the above liquid chromatography conditions.

Compound represented by formula (3): 14.4 min Each compound is identified by fractionating a portion corresponding to the peak observed at the retention time, and ¹ H NMR, ¹³ C NMR, It can be carried out by mass spectrometry (MS), infrared absorption spectrum (IR spectrum) or the like.

<Physical properties of polycarbonate resin (A)>
Polycarbonate resin (A) has a ratio (Mw / Mn) of polystyrene-equivalent weight average molecular weight Mw and number average molecular weight Mn measured by gel permeation chromatography (GPC) of 3.0 or more and 5.0 or less. A range is preferable. Furthermore, (Mw / Mn) is more preferably in the range of 3.0 or more and 4.0 or less. When (Mw / Mn) is too small, the fluidity in the molten state increases and the moldability tends to decrease. On the other hand, if (Mw / Mn) is excessively large, the melt viscosity tends to increase and molding tends to be difficult.

  The polycarbonate resin (A) preferably has a pencil hardness according to JIS K5400 of HB or higher. The pencil hardness of the polycarbonate resin is more preferably F or higher, still more preferably H or higher, and most preferably 2H or higher. However, it is usually 3H or less. A polycarbonate resin having a pencil hardness of less than HB tends to scratch the surface, and a conventional bisphenol A type polycarbonate resin has an insufficient pencil hardness of 2B.

  The viscosity average molecular weight of the polycarbonate resin (A) is usually 12,000 or more, preferably 15,000 or more, more preferably 18,000 or more, particularly preferably 20,000 or more, and most preferably 22,000 or more. Further, it is usually 100,000 or less, preferably 50,000 or less, more preferably 40,000 or less, and particularly preferably 35,000 or less. If the viscosity average molecular weight is too low, flame retardancy and mechanical properties may be reduced. On the other hand, if the viscosity average molecular weight is too high, the fluidity is lowered and the amount of foreign matter may be increased.

It is preferable that the YI value of a 3 mm-thick molded product molded from the polycarbonate resin (A) is 0 or more and 4 or less and the L ^* value is 96.0 or more and 96.5 or less. By using such a polycarbonate resin of YI value and L ^* value, and reducing the yellowness of the resin itself and improving the brightness, molded products and the like molded from this resin are excellent in color tone and have little haze. can do. Furthermore, when the resin composition is made by adding a bluing agent or the like to this resin, the amount of bluing agent added for improving the color tone (from a yellowish state to a state close to colorless) can be reduced. it can. In addition to reducing the amount of blueing agent used, this also has the effect of lowering the brightness as typified by the L ^* value. From the point of color tone and dullness of the resulting resin composition and its molded product It also contributes to making an excellent resin molded product.
The YI value of the molded product having a thickness of 3 mm molded from the polycarbonate resin composition defined in the present application not containing a polycarbonate resin (A) and a colorant such as a bluing agent is preferably 0 or more and 3.5 or less, It is more preferably 0.5 or more and 3.0 or less, and most preferably 1.0 or more and 2.0 or less. If the YI value is too large, the molded product becomes yellow, which is not preferable.
The L ^* value of the molded product having a thickness of 3 mm formed from the polycarbonate resin composition (A) and the polycarbonate resin composition defined in the present application not containing a colorant such as a bluing agent is 95.0 or more and 96.5 or less. 95.5 or more and 96.4 or less are preferable, and 96.0 or more and 96.3 or less are most preferable. If the L ^* value is too low, the molded product will be dull, which is not preferable.

Polycarbonate resin (A), the long form of the periodic table Group 1 and repeating units 1 mol per 5.0 × 10 the content amount of Group II metal is derived from all dihydroxy compounds constituting the polycarbonate resin ^- It is preferably ⁶ mol or less. More preferably, it is in the range of 1.0 × 10 ^{−7 to} 5.0 × 10 ⁻⁶ mol, still more preferably in the range of 0.5 × 10 ^{−6 to} 4.0 × 10 ⁻⁶ mol, particularly preferably. Is in the range of 1.0 × 10 ^{−6 to} 3.0 × 10 ⁻⁶ mol. If the amount is less than the above lower limit, the color tone and lightness may be deteriorated. If the amount is large, the polymer hue is deteriorated, gel-like substances or foreign matters insoluble in the solvent are generated, and the appearance defect and the mechanical properties of the polycarbonate resin are lowered. There is a risk.

<Production method of polycarbonate resin (A)>
The method for producing the polycarbonate resin (A) used in the present invention is not particularly limited, and any method can be adopted. Examples thereof include an interfacial polymerization method, a melt polymerization method, a pyridine method, a ring-opening polymerization method of a cyclic carbonate compound, and a solid phase transesterification method of a prepolymer.
Hereinafter, a particularly preferable one of these methods will be specifically described.

-Interfacial polymerization method First, the case where a polycarbonate resin (A) is manufactured by the interfacial polymerization method will be described.
In the interfacial polymerization method, the aromatic dihydroxy compound represented by the above formula (1) and a carbonate precursor (preferably phosgene are preferably maintained in the presence of an organic solvent inert to the reaction and an aqueous alkaline solution, usually at a pH of 9 or higher. ) And then interfacial polymerization in the presence of a polymerization catalyst to obtain a polycarbonate resin. In the reaction system, a molecular weight adjusting agent (terminal terminator) may be present if necessary, and an antioxidant may be present for the purpose of preventing oxidation of the dihydroxy compound.

  Examples of the organic solvent inert to the reaction include chlorinated hydrocarbons such as dichloromethane, 1,2-dichloroethane, chloroform, monochlorobenzene and dichlorobenzene; aromatic hydrocarbons such as benzene, toluene and xylene; It is done. In addition, 1 type may be used for an organic solvent and it may use 2 or more types together by arbitrary combinations and a ratio.

Examples of the alkali compound contained in the alkaline aqueous solution include alkali metal compounds and alkaline earth metal compounds such as sodium hydroxide, potassium hydroxide, lithium hydroxide, and sodium hydrogen carbonate. Among them, sodium hydroxide and Potassium hydroxide is preferred. In addition, an alkali compound may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
Although there is no restriction | limiting in the density | concentration of the alkali compound in alkaline aqueous solution, Usually, in order to control pH in the alkaline aqueous solution of reaction to 10-12, it is used at 5-10 mass%. For example, when phosgene is blown, the molar ratio of the bisphenol compound and the alkali compound is usually 1: 1.9 or more in order to control the pH of the aqueous phase to be 10 to 12, preferably 10 to 11. In particular, it is preferably set to 1: 2.0 or more, usually 1: 3.2 or less, and more preferably 1: 2.5 or less.

  Examples of the polymerization catalyst include aliphatic tertiary amines such as trimethylamine, triethylamine, tributylamine, tripropylamine, and trihexylamine; alicyclic rings such as N, N′-dimethylcyclohexylamine and N, N′-diethylcyclohexylamine. Tertiary amines; aromatic tertiary amines such as N, N′-dimethylaniline and N, N′-diethylaniline; quaternary ammonium salts such as trimethylbenzylammonium chloride, tetramethylammonium chloride and triethylbenzylammonium chloride Pyridine; guanine; guanidine salt; and the like. In addition, 1 type may be used for a polymerization catalyst and it may use 2 or more types together by arbitrary combinations and a ratio.

Examples of the molecular weight regulator include aromatic phenols having a monovalent phenolic hydroxyl group; aliphatic alcohols such as methanol and butanol; mercaptans; phthalimides, and the like. Among them, aromatic phenols are preferable.
Specific examples of such aromatic phenols include alkyl groups such as m-methylphenol, p-methylphenol, m-propylphenol, p-propylphenol, p-tert-butylphenol, and p-long chain alkyl-substituted phenol. Examples thereof include substituted phenols; vinyl group-containing phenols such as isopropanyl phenol; epoxy group-containing phenols; carboxyl group-containing phenols such as o-oxinebenzoic acid and 2-methyl-6-hydroxyphenylacetic acid; In addition, a molecular weight regulator may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.

  The usage-amount of a molecular weight regulator is 0.5 mol or more normally with respect to 100 mol of dihydroxy compounds, Preferably it is 1 mol or more, and is 50 mol or less normally, Preferably it is 30 mol or less. By making the usage-amount of a molecular weight modifier into this range, the thermal stability and hydrolysis resistance of a polycarbonate resin composition can be improved.

In the reaction, the order of mixing the reaction substrate, reaction medium, catalyst, additive and the like is arbitrary as long as a desired polycarbonate resin is obtained, and an appropriate order may be arbitrarily set. For example, when phosgene is used as the carbonate precursor, the molecular weight regulator can be mixed at any time as long as it is between the reaction (phosgenation) of the dihydroxy compound and phosgene and the start of the polymerization reaction.
In addition, reaction temperature is 0-40 degreeC normally, and reaction time is normally several minutes (for example, 10 minutes)-several hours (for example, 6 hours).

-Melt polymerization method Next, the case where a polycarbonate resin (A) is manufactured by the melt polymerization method (melt transesterification method) is demonstrated. In the melt polymerization exchange method, for example, an ester exchange reaction between an aromatic dihydroxy compound represented by the formula (1) and a carbonic acid diester is performed.

The dihydroxy compound is as described above.
On the other hand, examples of the carbonic acid diester include dialkyl carbonate compounds such as dimethyl carbonate, diethyl carbonate, and di-tert-butyl carbonate; diaryl carbonates such as diphenyl carbonate; and substituted diphenyl carbonates such as ditolyl carbonate. Of these, diaryl carbonate is preferable, and diphenyl carbonate is particularly preferable. In addition, 1 type may be used for carbonic acid diester, and it may use 2 or more types together by arbitrary combinations and a ratio.

  The ratio of the dihydroxy compound and the carbonic acid diester is arbitrary as long as the desired polycarbonate resin can be obtained, but it is preferable to use an equimolar amount or more of the carbonic acid diester with respect to 1 mol of the dihydroxy compound. It is more preferable. The upper limit is usually 1.30 mol or less. By setting it as such a range, the amount of terminal hydroxyl groups can be adjusted to a suitable range.

  In the polycarbonate resin, the amount of terminal hydroxyl groups tends to have a great influence on thermal stability, hydrolysis stability, color tone, and the like. For this reason, you may adjust the amount of terminal hydroxyl groups as needed by a well-known arbitrary method. In the transesterification reaction, a polycarbonate resin in which the terminal hydroxyl group amount is adjusted can be usually obtained by adjusting the mixing ratio of the carbonic acid diester and the dihydroxy compound, the degree of vacuum during the transesterification reaction, and the like. In addition, the molecular weight of the polycarbonate resin usually obtained can also be adjusted by this operation.

When adjusting the amount of terminal hydroxyl groups by adjusting the mixing ratio of the carbonic acid diester and the dihydroxy compound, the mixing ratio is as described above.
Further, as a more aggressive adjustment method, there may be mentioned a method in which a terminal terminator is mixed separately during the reaction. Examples of the terminal terminator at this time include monohydric phenols, monovalent carboxylic acids, carbonic acid diesters, and the like. In addition, 1 type may be used for a terminal terminator and it may use 2 or more types together by arbitrary combinations and a ratio.

  When producing a polycarbonate resin by the melt transesterification method, a transesterification catalyst is usually used. Any transesterification catalyst can be used. Among these, it is preferable to use an alkali metal compound and / or an alkaline earth metal compound. In addition, auxiliary compounds such as basic boron compounds, basic phosphorus compounds, basic ammonium compounds, and amine compounds may be used in combination. In addition, 1 type may be used for a transesterification catalyst and it may use 2 or more types together by arbitrary combinations and a ratio.

  In the melt polymerization method, the reaction temperature is usually 100 to 320 ° C. The pressure during the reaction is usually a reduced pressure condition of 2 mmHg or less (267 Pa or less). As a specific operation, a melt polycondensation reaction may be performed under the conditions in this range while removing by-products such as hydroxy compounds.

  The melt polycondensation reaction can be performed by either a batch method or a continuous method. In the case of a batch system, the order of mixing the reaction substrate, reaction medium, catalyst, additive, etc. is arbitrary as long as the desired polycarbonate resin is obtained, and an appropriate order may be set arbitrarily. However, in view of the stability of the polycarbonate resin and the polycarbonate resin composition, the melt polycondensation reaction is preferably carried out continuously.

In the melt polymerization method, a catalyst deactivator may be used as necessary. As the catalyst deactivator, a compound that neutralizes the transesterification catalyst can be arbitrarily used. Examples thereof include sulfur-containing acidic compounds and derivatives thereof. In addition, a catalyst deactivator may use 1 type and may use 2 or more types together by arbitrary combinations and a ratio.
The amount of the catalyst deactivator used is usually 0.5 equivalents or more, preferably 1 equivalent or more, and usually 10 equivalents or less, relative to the alkali metal or alkaline earth metal contained in the transesterification catalyst. Preferably it is 5 equivalents or less. Furthermore, it is 1 mass ppm or more normally with respect to polycarbonate resin, and is 100 mass ppm or less normally, Preferably it is 20 mass ppm or less.

Next, the phosphonite compound (B), the hindered phenol-based heat stabilizer (C) and the additive added as necessary will be described in the polycarbonate resin composition of the present invention.
The polycarbonate resin composition of the present invention is characterized in that it contains both the following phosphonite compound (B) and a hindered phenol heat stabilizer (C) as essential components in a predetermined ratio. By using such a heat stabilizer in combination, deterioration of transparency at the time of molding or the like is suppressed even when the polycarbonate resin (A) having the specific structural unit is used as a raw material, surface hardness, scratch resistance, The polycarbonate resin composition is excellent in thermal stability, hue, and mechanical strength.

[Phosphonite compound (B)]
The phosphonite compound (B) is a phosphorus compound represented by the following formula (5) or (6).

In Formula (5), R ⁷ represents a substituted or unsubstituted aryl group, and R ⁸ and R ⁹ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or A substituted or unsubstituted aryl group is shown.
In the formula (6), R ¹⁰ represents a substituted or unsubstituted aryl residue, and R ¹¹ , R ¹² , R ¹³ and R ¹⁴ each independently represents a hydrogen atom, a substituted or unsubstituted carbon number. 1 to 20 or less alkyl group, or a substituted or unsubstituted aryl group.

As such a phosphonite compound represented by the formula (5), for example,
Bis (2,4-di-iso-propylphenyl) -4-phenyl-phenylphosphonite, bis (2,4-di-n-butylphenyl) -3-phenyl-phenylphosphonite, bis (2,4- Di-tert-butylphenyl) -4-phenyl-phenylphosphonite, bis (2,4-di-tert-butylphenyl) -3-phenyl-phenylphosphonitebis (2,6-di-iso-propylphenyl) -4-phenyl-phenylphosphonite, bis (2,6-di-n-butylphenyl) -3-phenyl-phenylphosphonite, bis (2,6-di-tert-butylphenyl) -4-phenyl-phenyl Examples thereof include phosphonite and bis (2,6-di-tert-butylphenyl) -3-phenyl-phenylphosphonite.

Moreover, as a phosphonite compound represented by Formula (6), for example,
Tetrakis (2,4-di-tert-butylphenyl) -1,3′-phenylenephosphonite, tetrakis (2,4-di-tert-butylphenyl) -1,4′-phenylenephosphonite, tetrakis (2, 4-di-tert-butylphenyl) -1,2'-phenylenephosphonite, tetrakis (2,4-di-iso-propylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4-di -N-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4-di-tert-butylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4-di-tert) -Butylphenyl) -4,3'-biphenylenediphosphonite, tetrakis (2,4-di-tert-butylphenyl) -3,3'-bi Enylene diphosphonite, tetrakis (2,6-di-iso-propylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,6-di-n-butylphenyl) -4,4'-biphenyl Range phosphonite, tetrakis (2,6-di-tert-butylphenyl) -4,4'-biphenylene diphosphonite, tetrakis (2,6-di-tert-butylphenyl) -4,3'-biphenylene diphospho Knight, tetrakis (2,6-di-tert-butylphenyl) -3,3'-biphenylenediphosphonite,
Tetrakis (2,4-di-tert-butyl-5-methylphenyl) -4,4'-biphenylenediphosphonite, tetrakis (2,4-di-tert-butyl-5-methylphenyl) -4,3 ' -Biphenylene diphosphonite, tetrakis (2,4-di-tert-butyl-5-methylphenyl) -3,3'-biphenylene diphosphonite,
Etc.

As the phosphonite compound represented by the formula (6), a biphenylene phosphonite compound represented by the following formula (2) is particularly preferable because of good heat resistance and good hue of the resin composition of the present invention.

In formula (2), R ³ , R ⁴ , R ⁵ and R ⁶ each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group. Show.

  Specific examples of such biphenylene-based phosphonite compounds are as described above. Among them, tetrakis (2,4-di-tert-butylphenyl) -4,4′-biphenylenediphosphonite, tetrakis (2,4- Di-tert-butyl-5-methylphenyl) -4,4′-biphenylenediphosphonite is preferred.

Content of a phosphonite compound (B) is 0.001-0.5 mass part with respect to a total of 100 mass parts of polycarbonate resin (A), Preferably it is 0.005-0.4 mass part, More preferably, it is 0.01-0.3 mass part, Most preferably, it is 0.015-0.25 mass part.
When there is too much content of a phosphonite compound (B), wet heat resistance falls, and a dirt adheres to a metal mold | die at the time of shaping | molding, and is unpreferable. Moreover, when there is too little content of a phosphonite compound (B), transparency and a hue may deteriorate, and it is unpreferable.

[Hindered phenol heat stabilizer (C)]
The hindered phenol-based heat stabilizer (C) is a hindered phenol-based heat stabilizer having a melting point of 100 ° C. or lower, specifically, 2,6-di-tert-butyl-4-methylphenol (BHT). ), Triethylene glycol-bis [3- (3-tert-butyl-4-hydroxy-5-methylphenyl] propionate], thiodiethylenebis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) ) Propionate], ethylenebis (oxyethylene) bis [3- (5-tert-butyl-4-hydroxy-m-tolyl) propionate], 2,4-dimethyl-6- (1-methylpentadecyl) phenol, bis (3-t-butyl-4-hydroxy-5-methylbenzenepropanoic acid) ethylenebis (oxyethylene), a compound represented by the following formula (4): It is below.

  In formula (4), n is an integer of 1 to 25, preferably an integer of 15 to 20.

  Examples of the compound represented by the formula (4) include octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate.

  Examples of the hindered phenol heat stabilizer (C) include octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, octadecyl-3- (3,5-di-t-). Butyl-4-hydroxyphenyl) propiate or bis (3-tert-butyl-4-hydroxy-5-methylbenzenepropanoic acid) ethylenebis (oxyethylene) is preferred, octadecyl-3- (3,5-di-tert -Butyl-4-hydroxyphenyl) propionate is more preferred.

Content of a hindered phenol type heat stabilizer (C) is 0.01-0.5 mass part with respect to a total of 100 mass parts of polycarbonate resin (A), Preferably it is 0.02-0.45. It is 0.05 mass part, More preferably, it is 0.05-0.4 mass part, Most preferably, it is 0.08-0.3 mass part.
If the content of the hindered phenol heat stabilizer (C) is too large or too small, the transparency and hue may be deteriorated, which is not preferable.

[Other additives]
The polycarbonate resin composition of the present invention is blended with additives other than the phosphonite compound (B) and the hindered phenol heat stabilizer (C) (hereinafter referred to as “other additives”) as necessary. You can also Other additives include, for example, a flame retardant, an anti-dripping agent, a stabilizer, an ultraviolet absorber, a release agent, a colorant, an antistatic agent, a thermoplastic resin disclosed in JP2013-64046A, etc. Examples thereof include thermoplastic elastomers, glass fibers, glass flakes, glass beads, carbon fibers, wollastonite, calcium silicate, aluminum borate whiskers and the like.
In addition, what is necessary is just to determine suitably the addition amount of the other additive with respect to a polycarbonate resin composition in the range which does not impair the objective of this invention.

<Manufacture of polycarbonate resin composition>
When producing the polycarbonate resin composition of the present invention, a method of mixing the polycarbonate resin (A), the phosphonite compound (B), the hindered phenol heat stabilizer (C), and the above-mentioned additives blended as necessary. Is not particularly limited, and a wide variety of known methods for producing polycarbonate resin compositions can be employed.
Specific examples include polycarbonate resin (A), phosphonite compound (B), hindered phenol-based heat stabilizer (C), and other components such as the above-mentioned additives blended as necessary, such as a tumbler or Henschel mixer. Examples of the method include premixing using various mixers such as Banbury mixer, roll, Brabender, single-screw kneading extruder, twin-screw kneading extruder, kneader, and the like.

In addition, for example, without mixing each component in advance, or only a part of the components is mixed in advance, and fed to an extruder using a feeder and melt-kneaded to produce the polycarbonate resin composition of the present invention. You can also.
Also, for example, by mixing a part of the components in advance and supplying the resulting mixture to an extruder and melt-kneading it as a master batch, this master batch is again mixed with the remaining components and melt-kneaded. The polycarbonate resin composition of the present invention can also be produced.

<Polycarbonate resin molding>
A polycarbonate resin molded article is produced using the above-described polycarbonate resin composition of the present invention. The molding method of the polycarbonate resin molded body is not particularly limited, and examples thereof include a method of molding using a conventionally known molding machine such as an injection molding machine or an extrusion molding machine.
The polycarbonate resin molded article formed by molding the resin composition of the present invention is a molded article having both high surface hardness and high impact resistance and excellent transparency.

  Since the polycarbonate resin composition of the present invention provides a resin molded article having excellent surface hardness, scratch resistance, thermal stability, hue, and mechanical strength as described above, for example, a display device member or a display device It is particularly suitable as a cover, a protective device, a casing of an electric / electronic device or its cover, a vehicle-mounted component, a single layer or a multilayer sheet.

Examples of the display device member include constituent members of various display (display) devices (liquid crystal panels and touch panels), and examples of the display device cover include these various display devices, multifunctional mobile phones, smart phones, PDAs, and tablets. Examples thereof include a protective cover and a front panel of a type terminal, a personal computer, etc., and a cover of a display unit of a next-generation wattmeter, for example.
Examples of the transparent protector include a face cover (face guard) such as a helmet, a transparent shield, and the like.
Examples of casings or covers for electrical / electronic equipment include, for example, televisions, radio cassettes, video cameras, audio players, DVD players, multifunctional mobile phones, smart phones, PDAs, tablet terminals, personal computers, calculators, copiers, printers And a casing or cover of an electric / electronic device such as a facsimile.
In addition, as in-vehicle transparent parts, for example, glazing, resin window, headlamp lens, front (outside) member of car navigation (car audio, car AV, etc.), housing, etc., console box, center cluster, meter cluster Car interior parts such as front members are listed.
Furthermore, it is suitable for applications (liquid crystal display device members, transparent sheets, building materials, etc.) that require hardness, impact resistance, and transparency as single layer or multilayer sheets by single layer or multilayer extrusion.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited to a following example, unless the summary is changed. In addition, the physical property of the polycarbonate resin composition used in the Example was evaluated by the following method.

(1) Viscosity average molecular weight (Mv)
A polycarbonate resin was dissolved in methylene chloride (concentration 6.0 g / L) to obtain a solution. Using this solution, the specific viscosity (ηsp) at 20 ° C. was measured with an Ubbelohde viscosity tube, and the viscosity average molecular weight (Mv) was calculated by the following formula.
ηsp / C = [η] (1 + 0.28ηsp)
[η] = 1.23 × 10 ⁻⁴ Mv ^0.83

(2) Terminal hydroxyl group content The terminal hydroxyl group concentration of the polycarbonate resin was measured by colorimetric determination according to the titanium tetrachloride / acetic acid method (see Makromol. Chem. 88, 215 (1965)).

(3) Quantification of structural unit derived from compound represented by formula (3) After dissolving 0.5 g of polycarbonate resin in 5 mL of methylene chloride, 45 mL of methanol and 5 mL of 25 wt% aqueous sodium hydroxide solution were added, Stir for 30 minutes. The obtained solution is analyzed by liquid chromatography, and the structural unit derived from the compound represented by the formula (3) is quantified. The quantification was performed using a calibration curve created by quantification of the repeating unit represented by the formula (1).

Liquid chromatography measurement was performed by the following method.
Device: Shimadzu Corporation System Controller: CBM-20A
Pump: LC-10AD
Column oven: CTO-10ASvp
Detector: SPD-M20A
Analytical column: YMC-Pack ODS-AM 75 mm × Φ4.6 mm
Oven temperature: 40 ° C
Detection wavelength: 280 nm
Eluent: A solution: 0.1% trifluoroacetic acid aqueous solution, B solution: acetonitrile A / B = 60/40 (vol%) to A / B = 95/5 (vol%) in 25 minutes Gradient flow rate: 1 mL / Min
Sample injection volume: 20 μL
Moreover, the compound which is a structural unit derived from the compound represented by Formula (3) was observed at the following retention time under the above liquid chromatography conditions.

Compound represented by formula (3): 14.4 minutes Specific identification of each compound was carried out by separating a portion corresponding to the peak observed at the retention time, and ¹ H NMR, ¹³ C NMR, Two-dimensional NMR method, mass spectrometry (MS) and infrared absorption spectrum method (IR spectrum) were used.

  The compound represented by the formula (3) was identified from the molecular weight of the sample obtained by mass spectrometry, the NMR spectrum signal, and the signal derived from carboxylic acid in the IR spectrum.

(4) Pencil hardness of polycarbonate resin composition surface Using an injection molding machine (J50E2 manufactured by Nippon Steel Works), under conditions of barrel temperature 280 ° C. and mold temperature 90 ° C., thickness 3 mm, length 60 mm, width 60 mm A polycarbonate resin plate (molded article) or a polycarbonate resin composition plate (molded article) was injection molded. About this molded object, the pencil hardness measured by 750g load was calculated | required using the pencil hardness tester (made by Toyo Seiki Co., Ltd.) based on ISO15184.

(5) Yellow index (YI), L ^* value of polycarbonate resin composition Yellow index (YI), L with a spectrocolorimeter (CM-3700d manufactured by Minolta Co., Ltd.) using the molded body molded in (1) above. ^* Measured value. The smaller the value, the better the color tone.

  In addition, the polycarbonate resin used by the Example and the comparative example is as follows.

(I) Polycarbonate resin (A)
Reference Example 1 Synthesis of PC (A1) Synthesis of BPC homopolymer (Mv = 26,000) (melt polymerization method):
As the dihydroxy compound, 360 kg of 2,2-bis (4-hydroxy-3-methylphenyl) propane (BPC) (Honshu Chemical Co., Ltd.) was charged into the raw material receiving silo, and nitrogen substitution was performed 5 times. Next, 310 kg (1.03 mol with respect to 1 mol of BPC) of diphenyl carbonate (hereinafter may be abbreviated as “DPC”) was charged into the raw material adjustment tank and heated to 140 ° C. The aforementioned BPC was introduced into the raw material adjustment tank from the raw material receiving silo and stirred to obtain a raw material adjustment liquid. At this time, the inert gas was flowed through the raw material adjusting tank seven times as much as the flow rate of the inert gas per hour (standard state) with respect to the volume of the gas phase part of the raw material preparing tank. Furthermore, this raw material adjustment liquid was transferred to a raw material storage tank heated to 140 ° C. connected via a transfer pipe. In the raw material storage tank, an inert gas flow rate (standard state) of inert gas per hour was passed seven times the volume of the gas phase part of the raw material preparation tank. The average residence time of the raw material adjustment tank was 2 hours, and the average residence time of the raw material storage tank was 4 hours.
Next, a polycarbonate was produced under the following conditions using a continuous production apparatus having three vertical stirring reactors and one horizontal stirring reactor. First, each reactor was set in advance to the internal temperature and pressure according to the reaction conditions as described below.

First vertical reactor: internal temperature 220 ° C. pressure 13.3 kPa average residence time 80 minutes Second vertical reactor: internal temperature 260 ° C. pressure 4 kPa average residence time 67 minutes Third vertical reactor: internal temperature 272 ° C. pressure 200 Pa Average residence time 67 minutes Fourth horizontal reactor: Internal temperature 282 ° C. Pressure 120 Pa Average residence time 74 minutes

Subsequently, this raw material adjustment liquid was continuously supplied from the raw material storage tank into the first vertical reactor. The flow rate was set so that the theoretically produced polymer amount was 45 kg / hr.
The liquid level was kept constant while controlling the opening of the valve provided in the polymer discharge line at the bottom of the tank so that the average residence time of the first vertical reactor was 80 minutes. Simultaneously with the start of the supply of the raw material mixed melt, an aqueous cesium carbonate solution as a catalyst was continuously supplied into the first vertical stirring reactor from the catalyst supply port so that cesium carbonate was 3.0 μmol with respect to 1 mol of BPC.

  The polymerization reaction liquid discharged from the bottom of the first vertical reactor was continuously supplied to the second vertical reactor, the third vertical reactor, and the fourth horizontal reactor (biaxial spectacle blade stirring blade, L / At D = 4), continuous supply was performed sequentially. During the polymerization reaction, the liquid level of each reactor was controlled so that the above-mentioned average residence time was obtained.

  The molten polycarbonate extracted from the fourth horizontal stirring reactor was transferred to an extruder by a gear pump. The extruder (manufactured by Nippon Steel Works: twin screw extruder TEX30α: L / D = 42) had three vent ports and was devolatilized from the vent ports using a vacuum pump. At this time, the pressure in the vent portion was 1 kPa or less in absolute pressure.

  A gear pump is arranged on the resin discharge side of the extruder, and further downstream is a leaf disk filter (manufactured by Nippon Pole Co., Ltd.) having an outer diameter of 112 mm, an inner diameter of 38 mm, and a filtration accuracy of 99% within the containment vessel. A polymer filter equipped with 23 sheets was arranged. A die for forming a strand was attached to the discharge side of the polymer filter. The discharged resin was cooled with water and solidified in the form of a strand, and then pelletized with a rotary cutter. The process from stranding to pelletization was performed in a clean room. Subsequently, the pellets were sent to the product hopper by pneumatic transfer. When the obtained polycarbonate resin (PC (A1)) was evaluated by the method (2) above, the terminal hydroxyl group content of PC (A1) was 800 ppm.

(Ii) Phosphonite compound (B)
(B2) Tetrakis (2,4-di-t-butylphenyl) -4,4′-biphenylenediphosphonite (melting point: 90 ° C., manufactured by Adeka), corresponding to the structure defined by the present formula (2) (B5 ) Tetrakis (2,4-di-t-butyl-5-methylphenyl) -4,4′-biphenylenediphosphonite (melting point: 100 ° C., manufactured by Sakai Chemical Co., Ltd.) Applicable

(Iii) Hindered phenol heat stabilizer (C)
(C1) Octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propiate (melting point: 50 ° C., manufactured by BASF)
(C2) Bis (3-t-butyl-4-hydroxy-5-methylbenzenepropanoic acid) ethylene bis (oxyethylene) (melting point: 78 ° C., manufactured by BASF)
(C3) Pentaerythritol tetrakis (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate) (melting point: 120 ° C., manufactured by BASF)
(C4) 1,3,5-trimethyl-2,4,6-tris (3 ′, 5′-di-t-butyl-4′-hydroxybenzyl) benzene (melting point: 240 ° C., manufactured by BASF)

(Iv) Phosphorus heat stabilizer generally used (B1) Octadecyl pentaerythritol diphosphite (melting point: 52 ° C., manufactured by Adeka)
(B3) Pentaerythritol tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propiate (melting point: 183 ° C., manufactured by Adeka)
(B4) Pentaerythritol bis [(2,6-di-t-butyl-4-methylphenyl) phosphite] (melting point: 240 ° C., manufactured by Adeka)

"Example 1"
Polycarbonate resin (PC (A1)) is melted and kneaded with a twin-screw extruder (LABOTEX30HSS-32) manufactured by Nippon Steel Works with one vent port, extruded in the form of a strand from the outlet of the twin-screw extruder, and cooled and solidified with water. Then, it was pelletized with a rotary cutter to obtain polycarbonate resin pellets. Polycarbonate resin was supplied to the twin screw extruder at 15 kg / hr, and at the same time, a heat stabilizer as shown in Table 1 was added. At this time, the barrel temperature of the twin screw extruder was 280 ° C., and the polycarbonate resin temperature at the outlet of the twin screw extruder was 305 ° C. During melt-kneading, the vent port of the twin screw extruder was connected to a vacuum pump, and the pressure at the vent port was controlled to 500 Pa.
Each evaluation was carried out on this polycarbonate resin according to the above-mentioned procedure. The results are shown in Table 1.

"Examples 2 to 5 and Comparative Examples 1 to 10"
A polycarbonate resin composition having the composition shown in Table 1 was prepared in the same manner as in Example 1, and each evaluation was performed according to the above procedure. The results are shown in Table 1.
By looking at Table 1, as in Examples 1 to 5, by combining the specific phosphorus-based heat stabilizer defined in the present application and the specific hindered phenol-based heat stabilizer defined in the present application, as in Comparative Examples 1-3. YI value and L ^* value are good as compared with the case where a phosphorus heat stabilizer and a hindered phenol heat stabilizer used in general polycarbonate are used, and a phosphorus type as in Comparative Examples 4-9. The YI value and L ^* value are significantly better than when the heat stabilizer or the hindered phenol heat stabilizer is used alone or when the heat stabilizer is not used as in Comparative Example 10. Recognize.

  According to the present invention, it is excellent in surface hardness, scratch resistance, thermal stability, hue, and mechanical strength, and is a member for a display device, a protective device, a casing of an electric / electronic device, a vehicle-mounted component, a single layer or a multilayer sheet A polycarbonate resin composition suitable for various uses such as the above and a molded product thereof can be obtained.

Claims (6)

With respect to 100 parts by mass of the polycarbonate resin (A) containing a structural unit derived from the aromatic dihydroxy compound represented by the following formula (1), 0.001 to 0.5 parts by mass of the phosphonite compound (B) and a melting point of 100 ° C. A polycarbonate resin composition comprising 0.01 to 0.5 parts by mass of the following hindered phenol heat stabilizer (C).

(In formula (1), R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group.) The polycarbonate resin composition according to claim 1, wherein the phosphonite compound (B) is represented by the following formula (2).

(In the formula (2), R ³ , R ⁴ , R ⁵ and R ⁶ are each independently a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group. Show.) The polycarbonate resin composition according to claim 1 or 2, wherein the content of the structural unit derived from the compound represented by the following formula (3) is 0.5 ppm or more and 30 ppm or less.
(In Formula (3), R ¹ and R ² each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 20 carbon atoms, or a substituted or unsubstituted aryl group.) The polycarbonate resin composition according to any one of claims 1 to 3, wherein the phosphonite compound (B) has a melting point of 100 ° C or lower.   The polycarbonate resin composition according to any one of claims 1 to 4, wherein the terminal OH group amount of the polycarbonate resin (A) is 100 ppm or more.   The polycarbonate resin (A) is a polycarbonate resin obtained by a melt polymerization method of an aromatic dihydroxy compound represented by the formula (1) and diaryl carbonate. 2. The polycarbonate resin composition according to item 1.