JP7617779B2 - Polycarbonate resin composition and molded article - Google Patents

Description

The present invention relates to a polycarbonate resin composition and a molded article.

Planar light source devices are incorporated into liquid crystal display devices used in personal computers, mobile phones, etc., to meet the demands of thinner, lighter, more energy-efficient, and higher definition displays. These planar light source devices are equipped with a wedge-shaped light guide plate with a uniformly inclined surface on one side or a flat light guide plate, in order to guide the incoming light uniformly and efficiently to the liquid crystal display side. Some light guide plates have a light scattering function provided by forming an uneven pattern on their surface.

Such light guide plates are obtained by injection molding of thermoplastic resin, and the above-mentioned uneven pattern is imparted by transferring unevenness formed on the surface of a nesting mold. Conventionally, light guide plates have been molded from resin materials such as polymethyl methacrylate (PMMA), but recently, there has been a demand for display devices that can project clearer images, and as a result, there is a tendency for the temperature inside the display device to rise due to heat generated near the light source. For this reason, the resin material of light guide plates is being replaced with a polycarbonate resin material that has higher heat resistance.

In general, polycarbonate resin is a resin with excellent mechanical, thermal, and electrical properties, and weather resistance. However, the light transmittance of polycarbonate resin is lower than that of resins that have been used in conventional light guide plates, such as PMMA. Therefore, when a surface light source is constructed from a light guide plate made of polycarbonate resin and a light source, there is a problem of low brightness. In addition, there has been a recent demand to reduce the chromaticity difference between the light entrance part of the light guide plate and a part away from the light entrance part, but polycarbonate resin has a problem of being more prone to yellowing than PMMA.

For example, Patent Document 1 proposes a method of improving light transmittance and brightness by adding an acrylic resin and an alicyclic epoxy compound to a polycarbonate resin. Patent Document 2 proposes a method of improving brightness by modifying the ends of a polycarbonate resin to improve the transferability of the unevenness to a light guide plate. Patent Document 3 proposes a method of improving brightness by introducing a copolyestercarbonate having an aliphatic segment to improve the transferability.

However, in the method described in Patent Document 1, although the hue is improved by adding an acrylic resin, it becomes cloudy, making it difficult to increase the light transmittance and brightness. Although the addition of an alicyclic epoxy compound may improve the transmittance, no improvement effect in the hue is observed. In the methods described in Patent Documents 2 and 3, although the effect of improving the fluidity and transferability of the resin constituting the light guide plate can be expected, there is a drawback in that the heat resistance is reduced.

On the other hand, it is known to blend compounds such as polyethylene glycol or poly(2-methyl)ethylene glycol with thermoplastic resins such as polycarbonate resins. For example, Patent Document 4 describes a gamma-ray radiation-resistant polycarbonate resin that contains this compound. Patent Document 5 describes a thermoplastic resin composition that is made by blending this compound with a resin such as PMMA and has excellent antistatic properties and surface appearance.

Patent Document 6 also proposes improving the transmittance and hue by blending a polyalkylene glycol composed of linear alkyl groups with a polycarbonate resin. For example, blending polytetramethylene ether glycol with a polycarbonate resin improves the transmittance and yellowness (yellow index: YI).

Furthermore, Patent Document 7 describes a method for producing a polycarbonate copolymer using a diol obtained by diesterifying a polyalkylene glycol as a raw material (comonomer). The polycarbonate copolymer described in Patent Document 7 has an unstable diester diol of polyalkylene glycol, and the color hue and heat discoloration resistance are also poor.

Japanese Patent Application Publication No. 11-158364 JP 2001-208917 A JP 2001-215336 A Japanese Patent Application Publication No. 1-22959 Japanese Patent Application Publication No. 9-227785 Patent No. 5699188 JP 2006-016497 A

In recent years, in the field of various information terminals such as smartphones, tablet terminals, and in-vehicle display devices, optical components such as light guide plates have been getting thinner and larger at a remarkable speed. Molding such optical components requires high barrel temperatures and high-speed injection. Accordingly, resin compositions used in molding optical components are required to have not only excellent optical properties such as good hue and transparency, but also high fluidity suitable for injection molding.

The present invention has been made in consideration of the above circumstances, and its object is to provide a polycarbonate resin composition and molded article having high fluidity, good hue, and excellent transparency.

As a result of extensive research into solving the above problems, the inventors discovered that by blending a polyether polycarbonate resin having a molecular weight within a specific range with a polycarbonate resin in a specific ratio, a polycarbonate resin composition having high fluidity, good hue, and excellent transparency can be obtained, and thus completed the present invention.

In other words, in order to solve the above-mentioned problems and achieve the object, the polycarbonate resin composition according to the present invention is characterized in that it contains 0.01 to 5 parts by mass of a polyether polycarbonate resin (B) having a polyether and a carbonate bond per 100 parts by mass of a polycarbonate resin (A), and that the weight average molecular weight (Mw) of the polyether polycarbonate resin (B) is 1,000 or more and less than 8,000 in terms of polystyrene measured by gel permeation chromatography using chloroform as a solvent.

The polycarbonate resin composition according to the present invention is characterized in that, in the above invention, the polyether polycarbonate resin (B) is a copolymer represented by the following general formula (1):

（一般式（１）中、Ｒ_ZおよびＲ_Xは、各々独立に、水素原子または炭素数１～３のアルキル基を示す。Ｒ_ZおよびＲ_Xは各々複数存在し、複数のＲ_ZおよびＲ_Xは、各々同じであってもよいし異なっていてもよい。ｉは２～１０の整数を示し、ｐは１～６００の整数を示し、ｎは１～３０００の整数を示す。）

(In general formula (1), R _Z and R _X each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. There are a plurality of R _Z and R _X , and the plurality of R _Z and R _X may be the same or different. i represents an integer of 2 to 10, p represents an integer of 1 to 600, and n represents an integer of 1 to 3000.)

The polycarbonate resin composition according to the present invention is characterized in that in the above invention, i in the general formula (1) is 3 or 4.

The polycarbonate resin composition according to the present invention is characterized in that it further contains 0.005 to 0.5 parts by mass of a phosphorus-based stabilizer (C) per 100 parts by mass of the polycarbonate resin (A).

The polycarbonate resin composition according to the present invention is characterized in that, in the above invention, the initial YI value of the polycarbonate resin composition at an optical path length of 300 mm is 25.0 or less, and the difference ΔYI between the YI value of the polycarbonate resin composition at an optical path length of 300 mm after being held at 95°C for 250 hours and the initial YI value is 6.0 or less.

The molded article according to the present invention is characterized in that it is made of the polycarbonate resin composition according to any one of the above inventions.

The molded article according to the present invention is also characterized in that it is an optical component in the above invention.

The present invention has the effect of providing a polycarbonate resin composition and molded article having high fluidity, good hue, and excellent transparency.

The following provides a detailed description of preferred embodiments of the polycarbonate resin composition and molded article according to the present invention. The present invention is not limited to the embodiments described below. In addition, in this specification, unless otherwise specified, the notation "~" is used to mean that the numerical values before and after it are included as the lower and upper limits.

The polycarbonate resin composition according to an embodiment of the present invention contains 0.01 to 5 parts by mass of polyether polycarbonate resin (B) per 100 parts by mass of polycarbonate resin (A). In this polycarbonate resin composition, the weight average molecular weight (Mw) of the polyether polycarbonate resin (B) is 1,000 or more and less than 8,000 in terms of polystyrene by gel permeation chromatography using chloroform as a solvent. Below, each component constituting the polycarbonate resin composition according to an embodiment of the present invention and a molded article made of this polycarbonate resin composition will be described in detail.

[Polyether polycarbonate resin (B)]
First, the polyether polycarbonate resin (B), which is one component constituting the polycarbonate resin composition according to the embodiment of the present invention, will be described in detail. The polyether polycarbonate resin (B) used in the present invention is a resin having a polyether and a carbonate bond.

In detail, the polyether of the polyether polycarbonate resin (B) is, for example, a polyalkylene glycol. This polyalkylene glycol may or may not have a substituent. The polyether polycarbonate resin (B) is composed of such a polyether and a carbonate bond. In the present invention, the polyether polycarbonate resin (B) is preferably a copolymer composed of a polyalkylene glycol bonded via a carbonate bond, that is, a copolymer represented by the following general formula (1).

In general formula (1), R _Z and R _X each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. There are multiple R _Z and multiple R _X , and these multiple R _Z and R _X may be the same or different. i represents an integer of 2 to 10. p represents an integer of 1 to 600. n represents an integer of 1 to 3000.

The polyether polycarbonate resin (B) can be produced by a conventional production method such as an interfacial polymerization method or a melt polymerization method. For example, the polyether polycarbonate resin (B) can be produced by a method of reacting a polyalkylene glycol with phosgene, or a method of reacting a polyalkylene glycol with a carbonate precursor such as ethylene carbonate or diphenyl carbonate.

In the polyether polycarbonate resin (B), various polyalkylene glycols can be used as the polyalkylene glycol that may have a substituent. For example, a preferred example of the polyalkylene glycol is a branched polyalkylene glycol represented by the following general formula (2):

In general formula (2), R represents an alkyl group having 1 to 3 carbon atoms. q represents an integer from 2 to 400. The branched polyalkylene glycol represented by general formula (2) may be a homopolymer having one type of R, or a copolymer having two or more types of R.

Preferred specific examples of the branched polyalkylene glycol represented by the general formula (2) include polypropylene glycol and polybutylene glycol. The polypropylene glycol is a branched polyalkylene glycol in which R=CH ₃ (methyl group) in the general formula (2), and is a polyether polycarbonate resin (B) in which i=2, R _Z =CH ₃ , and R _X =H in the general formula (1). The polybutylene glycol is a branched polyalkylene glycol in which R=CH ₃ CH ₂ (ethyl group) in the general formula (2), and is a polyether polycarbonate resin (B) in which i=2, R _Z =CH ₃ CH ₂ , and R _X =H in the general formula (1). Commercially available branched polyalkylene glycols include, for example, trade names "UNIOL D-1000" and "UNIOL PB-1000" manufactured by NOF Corporation.

In the polyether polycarbonate resin (B), the polyalkylene glycol which may have a substituent may be a straight-chain polyalkylene glycol. As the straight-chain polyalkylene glycol, for example, polyethylene glycol (i=2 in the general formula (1), _RZ = _Rx =H), polytrimethylene glycol (i=3 in the general formula (1), _RZ = _Rx =H), polytetramethylene glycol (i=4 in the general formula (1), _RZ = _Rx =H), polypentamethylene glycol (i=5 in the general formula (1), _RZ = _Rx =H), polyhexamethylene glycol (i=6 in the general formula (1), _RZ = _Rx =H), etc. are preferable. Among them, as the polyalkylene glycol, polytrimethylene glycol or polytetramethylene glycol is particularly preferable. That is, it is particularly preferable that i in the general formula (1) is 3 or 4. Moreover, the substituents of the polyalkylene glycol (R _Z and R _X in the general formula (1)) are preferably hydrogen atoms.

As a commercially available product of polytrimethylene glycol, there may be mentioned a commercially available product of polytrimethylene glycol in which R _Z and R _X in the general formula (1) are hydrogen atoms. As a commercially available product of this polytrimethylene glycol, for example, the trade name "Velvetol" manufactured by Allessa may be mentioned. In addition, as a commercially available product of polytetramethylene glycol, there may be mentioned a commercially available product of polytetramethylene glycol in which R _Z and R _X in the general formula (1) are hydrogen atoms. As a commercially available product of this polytetramethylene glycol, there may be mentioned, for example, the trade name "PTMG" manufactured by Mitsubishi Chemical Corporation.

In addition, in the polyether polycarbonate resin (B), the polyalkylene glycol, which may have a substituent, may be a polyalkylene glycol copolymer having a linear alkylene ether unit represented by the following general formula (3) and a branched alkylene ether unit selected from units represented by any one of the following general formulas (4-1) to (4-4).

In general formula (3), p represents an integer from 2 to 6. The linear alkylene ether unit represented by general formula (3) may be a single unit having a specific integer p, or may be a mixture of multiple units having different integers p.

In general formulas (4-1) to (4-4), R ¹ to R ¹⁰ each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. In each of general formulas (4-1) to (4-4), at least one of R ¹ to R ¹⁰ is an alkyl group having 1 to 3 carbon atoms.

The branched alkylene ether unit of the polyalkylene glycol copolymer may be a homopolymer constituted by a branched alkylene ether unit having a structure represented by any one of general formulas (4-1) to (4-4). Alternatively, the branched alkylene ether unit may be a copolymer constituted by a branched alkylene ether unit having a plurality of structures selected from the structure represented by general formula (4-1), the structure represented by general formula (4-2), the structure represented by general formula (4-3), and the structure represented by general formula (4-4).

Examples of the linear alkylene ether unit represented by the general formula (3) include, in terms of glycol, ethylene glycol in which p is 2 in the general formula (3), trimethylene glycol in which p is 3 in the general formula (3), tetramethylene glycol in which p is 4 in the general formula (3), pentamethylene glycol in which p is 5 in the general formula (3), and hexamethylene glycol in which p is 6 in the general formula (3). The linear alkylene ether unit may be a mixture of these. Among these, trimethylene glycol and tetramethylene glycol are preferred as the linear alkylene ether unit, and tetramethylene glycol is particularly preferred.

Trimethylene glycol is industrially produced by either obtaining 3-hydroxypropionaldehyde through hydroformylation of ethylene oxide and then hydrogenating this, or by hydrating acrolein to obtain 3-hydroxypropionaldehyde, which is then hydrogenated using a Ni catalyst. Recently, trimethylene glycol has also been produced using a biomethod in which glycerin, glucose, starch, etc. are reduced by microorganisms.

Examples of the branched alkylene ether unit represented by general formula (4-1) include glycols such as (2-methyl)ethylene glycol, (2-ethyl)ethylene glycol, and (2,2-dimethyl)ethylene glycol. The branched alkylene ether unit represented by general formula (4-1) may be a mixture of two or more of these. As the branched alkylene ether unit represented by general formula (4-1), (2-methyl)ethylene glycol and (2-ethyl)ethylene glycol are preferred.

Examples of the branched alkylene ether unit represented by the general formula (4-2) include glycols such as (2-methyl)trimethylene glycol, (3-methyl)trimethylene glycol, (2-ethyl)trimethylene glycol, (3-ethyl)triethylene glycol, (2,2-dimethyl)trimethylene glycol, (2,2-methylethyl)trimethylene glycol, (2,2-diethyl)trimethylene glycol (i.e., neopentyl glycol), (3,3-dimethyl)trimethylene glycol, (3,3-methylethyl)trimethylene glycol, and (3,3-diethyl)trimethylene glycol. The branched alkylene ether unit represented by the general formula (4-2) may be a mixture of two or more of these.

Examples of glycols that may be used as branched alkylene ether units represented by the general formula (4-3) include (3-methyl)tetramethylene glycol, (4-methyl)tetramethylene glycol, (3-ethyl)tetramethylene glycol, (4-ethyl)tetramethylene glycol, (3,3-dimethyl)tetramethylene glycol, (3,3-methylethyl)tetramethylene glycol, (3,3-diethyl)tetramethylene glycol, (4,4-dimethyl)tetramethylene glycol, (4,4-methylethyl)tetramethylene glycol, and (4,4-diethyl)tetramethylene glycol. The branched alkylene ether units represented by the general formula (4-3) may be a mixture of two or more of these. Among these, (3-methyl)tetramethylene glycol is preferred as the branched alkylene ether unit represented by the general formula (4-3).

Examples of branched alkylene ether units represented by the general formula (4-4) include glycols such as (3-methyl)pentamethylene glycol, (4-methyl)pentamethylene glycol, (5-methyl)pentamethylene glycol, (3-ethyl)pentamethylene glycol, (4-ethyl)pentamethylene glycol, (5-ethyl)pentamethylene glycol, (3,3-dimethyl)pentamethylene glycol, (3,3-methylethyl)pentamethylene glycol, (3,3-diethyl)pentamethylene glycol, (4,4-dimethyl)pentamethylene glycol, (4,4-methylethyl)pentamethylene glycol, (4,4-diethyl)pentamethylene glycol, (5,5-dimethyl)pentamethylene glycol, (5,5-methylethyl)pentamethylene glycol, and (5,5-diethyl)pentamethylene glycol. The branched alkylene ether unit represented by general formula (4-4) may be a mixture of two or more of these.

In the above, the branched alkylene ether units represented by each of the general formulas (4-1) to (4-4) are exemplified as glycols for convenience, but the branched alkylene ether units are not limited to the above-mentioned glycols and may be their alkylene oxides or their polyether-forming derivatives.

As the polyalkylene glycol copolymer constituting the polyether polycarbonate resin (B), a copolymer consisting of tetramethylene ether units and branched alkylene ether units represented by the general formula (4-3) is preferred, and in particular, a copolymer consisting of tetramethylene ether units and 3-methyltetramethylene ether units is more preferred. As the polyalkylene glycol copolymer, a copolymer consisting of tetramethylene ether units and branched alkylene ether units represented by the general formula (4-1) is also preferred, and in particular, a copolymer consisting of tetramethylene ether units and 2-methylethylene ether units, and a copolymer consisting of tetramethylene ether units and 2-ethylethylene ether units are more preferred. As the polyalkylene glycol copolymer, a copolymer consisting of tetramethylene ether units and branched alkylene ether units represented by the general formula (4-2) is also preferred, and a copolymer consisting of 2,2-dimethyltrimethylene ether units, i.e., neopentyl glycol ether units, is also preferred.

The polyalkylene glycol copolymer constituting the polyether polycarbonate resin (B) may be a random copolymer or a block copolymer.

In the polyalkylene glycol copolymer, the copolymerization ratio of the linear alkylene ether unit represented by the general formula (3) to the branched alkylene ether unit represented by each of the general formulas (4-1) to (4-4) is preferably 95/5 to 5/95 in terms of the molar ratio of (linear alkylene ether unit)/(branched alkylene ether unit). The copolymerization ratio is more preferably 93/7 to 40/60, and even more preferably 90/10 to 65/35, and is particularly preferably rich in linear alkylene ether units. The molar fraction is measured using a ¹ H-NMR measurement device and deuterated chloroform as a solvent.

Among the above, particularly preferred homopolymers as the polyalkylene glycol constituting the polyether polycarbonate resin (B) are polytrimethylene glycol, poly(2-methyl)ethylene glycol, poly(2-ethyl)ethylene glycol, polytetramethylene glycol, etc. Also, particularly preferred copolymers as the polyalkylene glycol are polytetramethylene glycol-polyethylene glycol, polytetramethylene glycol-polytrimethylene glycol, polytetramethylene glycol-poly(2-methyl)ethylene glycol, polytetramethylene glycol-poly(3-methyl)tetramethylene glycol, polytetramethylene glycol-poly(2-ethyl)ethylene glycol, polytetramethylene glycol-polyneopentyl glycol, polyethylene glycol-polytrimethylene glycol, polyethylene glycol-poly(2-methyl)ethylene glycol, etc.

The polyalkylene glycol constituting the polyether polycarbonate resin (B) may contain a structure derived from a polyol such as 1,4-butanediol, glycerol, sorbitol, benzenediol, bisphenol A, hydrogenated bisphenol A, cyclohexanediol, or spiroglycol. By adding these polyols during polymerization of the polyalkylene glycol, these organic groups can be imparted to the main chain. Among these, glycerol, sorbitol, bisphenol A, etc. are particularly preferred.

Examples of polyalkylene glycols containing organic groups in their structure include polyethylene glycol glyceryl ether, poly(2-methyl)ethylene glycol glyceryl ether, poly(2-ethyl)ethylene glycol glyceryl ether, polytetramethylene glycol glyceryl ether, polyethylene glycol-poly(2-methyl)ethylene glycol glyceryl ether, polytetramethylene glycol-poly(2-methyl)ethylene glycol glyceryl ether, polytetramethylene glycol-poly(2-ethyl)polyethylene glycol glyceryl ether, polyethylene glycol sorbityl ether, poly(2-methyl)ethylene glycol sorbityl ether, poly(2-ethyl)ethylene glycol sorbityl ether, polytetramethylene glycol sorbityl ether, polyethylene glycol-poly(2-methyl)ethylene glycol sorbityl ether Preferred examples include butyl ether, polytetramethylene glycol-poly(2-methyl)ethylene glycol sorbityl ether, polytetramethylene glycol-poly(2-ethyl)ethylene glycol sorbityl ether, bisphenol A-bis(polyethylene glycol) ether, bisphenol A-bis(poly(2-methyl)ethylene glycol) ether, bisphenol A-bis(poly(2-ethyl)ethylene glycol) ether, bisphenol A-bis(polytetramethylene glycol) ether, bisphenol A-bis(polyethylene glycol-poly(2-methyl)ethylene glycol) ether, bisphenol A-bis(polytetramethylene glycol-poly(2-methyl)ethylene glycol) ether, and bisphenol A-bis(polytetramethylene glycol-poly(2-ethyl)polyethylene glycol) ether.

The weight average molecular weight (Mw) of the polyether (e.g., polyalkylene glycol) constituting the polyether polycarbonate resin (B) is preferably 100 or more and less than 8000, in a range below the Mw of the polyether polycarbonate resin (B) itself. The lower limit of the weight average molecular weight (Mw) of the polyalkylene glycol is more preferably 200 or more. The upper limit of the weight average molecular weight (Mw) of the polyalkylene glycol is more preferably 6000 or less, even more preferably 5000 or less, and particularly preferably 4000 or less. When the weight average molecular weight (Mw) of the polyalkylene glycol is 8000 or more, the compatibility between the polycarbonate resin (A) and the polyether polycarbonate resin (B) tends to decrease. When the weight average molecular weight (Mw) of the polyalkylene glycol is less than 100, the color improvement effect of the polycarbonate resin composition containing the polyether polycarbonate resin (B) decreases.

In the present invention, the weight average molecular weight (Mw) is a molecular weight measured in terms of polystyrene by gel permeation chromatography (GPC) using chloroform as a solvent (developing solvent). Specifically, GPC is performed using a Tosoh Corporation high-speed GPC device "HLC-8320," three Tosoh Corporation HZ-M (4.6 mm x 150 mm) columns in series, chloroform as the eluent, and a measurement temperature of 25°C. The polystyrene-equivalent molecular weight value thus determined is the weight average molecular weight (Mw) in the present invention.

Among the monomers that are the raw materials for polyether polycarbonate resin (B), examples of carbonate precursors include carbonyl halides and carbonate esters. As the raw material for polyether polycarbonate resin (B), one type of carbonate precursor may be used, or two or more types of carbonate precursors may be used in any combination and ratio.

Among the above carbonate precursors, examples of carbonyl halides include haloformates such as bischloroformates obtained by reacting phosgene with a dihydroxy compound, and monochloroformates of dihydroxy compounds.

Examples of carbonate esters include diaryl carbonates, dialkyl carbonates, and carbonates of dihydroxy compounds. Examples of diaryl carbonates include diphenyl carbonate and ditolyl carbonate. Examples of dialkyl carbonates include dimethyl carbonate, diethyl carbonate, and ethylene carbonate. Examples of carbonates of dihydroxy compounds include biscarbonates of dihydroxy compounds, monocarbonates of dihydroxy compounds, and cyclic carbonates.

The method for producing the polyether polycarbonate resin (B) is not particularly limited, and any known method can be used. For example, examples of the method for producing the polyether polycarbonate resin (B) include an interfacial polymerization method, a melt transesterification method, a pyridine method, a ring-opening polymerization method of a cyclic carbonate compound, and a solid-phase transesterification method of a prepolymer. Among these, the melt transesterification method and the interfacial polymerization method are preferred, and the melt transesterification method is more preferred. In addition, the type of polyalkylene glycol itself that is the raw material for the polyether polycarbonate resin (B) may be one type or two or more types. In addition, the polyalkylene glycol that is the raw material for the polyether polycarbonate resin (B) may contain multiple homopolymers, may contain multiple copolymers, or may be a mixture of these homopolymers and copolymers. For example, the polyalkylene glycol may contain multiple branched polyalkylene glycols, may contain multiple linear polyalkylene glycols, or may contain a mixture of the branched polyalkylene glycols and linear polyalkylene glycols.

The weight average molecular weight (Mw) of the polyether polycarbonate resin (B) is 1000 or more and less than 8000. The lower limit of the weight average molecular weight (Mw) of this polyether polycarbonate resin (B) is preferably 1500 or more. The upper limit of the weight average molecular weight (Mw) of this polyether polycarbonate resin (B) is preferably 7000 or less. When the weight average molecular weight (Mw) of the polyether polycarbonate resin (B) is 8000 or more, the compatibility between the polycarbonate resin (A) and the polyether polycarbonate resin (B) tends to decrease. When the weight average molecular weight (Mw) of the polyether polycarbonate resin (B) is less than 1000, gas tends to be generated easily from the polycarbonate resin composition during molding of a molded article made of the polycarbonate resin composition (i.e., the amount of gas generated tends to increase).

The weight average molecular weight (Mw) of the polyether polycarbonate resin (B) can be adjusted by selecting the Mw of the polyalkylene glycol, which is one of the comonomer diol raw materials, adjusting the ratio of the carbonate precursor, adding a terminator, adjusting the temperature and pressure during polymerization, and the like. For example, in the melt transesterification method, in order to increase the Mw of the polyether polycarbonate resin (B), the monomer raw material ratio is adjusted so that the reaction ratio between the carbonate precursor monomer diphenyl carbonate and the diol monomer is close to 1, the polymerization temperature is kept high so that the by-product phenol can be easily removed from the polymerization system, the pressure is kept as low as possible, and the interface is actively renewed by stirring. In addition, the Mw of the polyether polycarbonate resin (B) can also be adjusted by heating and stirring a mixture of the raw materials polytetramethylene glycol and ethylene carbonate, and then starting the transesterification reaction using a transesterification catalyst such as magnesium (II) acetylacetonate as a catalyst, and adjusting the raw material ratio to a predetermined ratio when heating and stirring.

The weight average molecular weight (Mw) of the polyether polycarbonate resin (B) can be measured by the same method as that for the weight average molecular weight (Mw) of the polyether described above. Specifically, GPC is performed using a Tosoh Corporation high-speed GPC device "HLC-8320," three Tosoh Corporation HZ-M (4.6 mm x 150 mm) columns in series, chloroform as the eluent, and a measurement temperature of 25°C. The polystyrene-equivalent molecular weight value obtained by this is the weight average molecular weight (Mw) of the polyether polycarbonate resin (B) in this embodiment.

In the polycarbonate resin composition according to the embodiment of the present invention, the content of polyether polycarbonate resin (B) is 0.01 to 5 parts by mass per 100 parts by mass of polycarbonate resin (A). The lower limit of the content of the polyether polycarbonate resin (B) is preferably 0.05 parts by mass or more, more preferably 0.1 parts by mass or more, per 100 parts by mass of polycarbonate resin (A). The upper limit of the content of the polyether polycarbonate resin (B) is preferably 4 parts by mass or less, more preferably 3 parts by mass or less, and particularly preferably 2 parts by mass or less, per 100 parts by mass of polycarbonate resin (A). If the content of polyether polycarbonate resin (B) is less than 0.01 parts by mass, the effect of improving the hue and heat discoloration resistance of the polycarbonate resin composition cannot be obtained. If the content of polyether polycarbonate resin (B) exceeds 5 parts by mass, the polycarbonate resin composition becomes cloudy and loses transparency.

[Polycarbonate resin (A)]
Next, the polycarbonate resin (A), which is one component constituting the polycarbonate resin composition according to the embodiment of the present invention, will be described in detail. The polycarbonate resin (A) used in the present invention is not particularly limited as long as it is other than the above-mentioned polyether polycarbonate resin (B), and various types of polycarbonate resins can be used.

In detail, polycarbonate resins can be classified into aromatic polycarbonate resins in which the carbons directly bonded to the carbonate bonds are aromatic carbons, and aliphatic polycarbonate resins in which the carbons are aliphatic carbons, and the polycarbonate resin (A) of the present invention may be either of these resins. Among these, aromatic polycarbonate resins are preferred as polycarbonate resin (A) from the viewpoints of heat resistance, mechanical properties, electrical properties, etc.

Among the monomers that are the raw materials for aromatic polycarbonate resins, examples of aromatic dihydroxy compounds include dihydroxybenzenes, dihydroxybiphenyls, dihydroxynaphthalenes, dihydroxydiaryl ethers, bis(hydroxyaryl)alkanes, bis(hydroxyaryl)cycloalkanes, cardo structure-containing bisphenols, dihydroxydiaryl sulfides, dihydroxydiaryl sulfoxides, and dihydroxydiaryl sulfones.

Examples of dihydroxybenzenes include 1,2-dihydroxybenzene, 1,3-dihydroxybenzene (i.e., resorcinol), 1,4-dihydroxybenzene, etc. Examples of dihydroxybiphenyls include 2,5-dihydroxybiphenyl, 2,2'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl, etc.

Examples of dihydroxynaphthalenes include 2,2'-dihydroxy-1,1'-binaphthyl, 1,2-dihydroxynaphthalene, 1,3-dihydroxynaphthalene, 2,3-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 2,6-dihydroxynaphthalene, 1,7-dihydroxynaphthalene, and 2,7-dihydroxynaphthalene.

Examples of dihydroxydiaryl ethers include 2,2'-dihydroxydiphenyl ether, 3,3'-dihydroxydiphenyl ether, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether, 1,4-bis(3-hydroxyphenoxy)benzene, and 1,3-bis(4-hydroxyphenoxy)benzene.

Examples of bis(hydroxyaryl)alkanes include 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A), 1,1-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-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(3,5-dimethyl-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)cyclohexylmethan , bis(4-hydroxyphenyl)phenylmethane, bis(4-hydroxyphenyl)(4-propenylphenyl)methane, bis(4-hydroxyphenyl)diphenylmethane, bis(4-hydroxyphenyl)naphthylmethane, 1,1-bis(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, 1,1-bis(4-hydroxyphenyl)-1-naphthylethan, 1,1-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl) 1,1-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, 4,4-bis(4-hydroxyphenyl)heptane, 2,2-bis(4-hydroxyphenyl)nonane, 1,1-bis(4-hydroxyphenyl)decane, 1,1-bis(4-hydroxyphenyl)dodecane, etc.

Examples of bis(hydroxyaryl)cycloalkanes include 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-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-hydroxyphenyl)-3,3,5-trimethylcyclohexane, Examples include 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)-4-tert-butyl-cyclohexane, 1,1-bis(4-hydroxyphenyl)-3-phenylcyclohexane, and 1,1-bis(4-hydroxyphenyl)-4-phenylcyclohexane.

Examples of bisphenols containing a cardo structure include 9,9-bis(4-hydroxyphenyl)fluorene and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene.

Examples of dihydroxydiaryl sulfides include 4,4'-dihydroxydiphenyl sulfide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfide.

Examples of dihydroxydiaryl sulfoxides include 4,4'-dihydroxydiphenyl sulfoxide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide.

Examples of dihydroxydiaryl sulfones include 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone.

Among these, bis(hydroxyaryl)alkanes are preferred. Among bis(hydroxyaryl)alkanes, bis(4-hydroxyphenyl)alkanes are preferred, and from the viewpoint of heat resistance, 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A) is particularly preferred.

As a raw material for the aromatic polycarbonate resin, for example, one type of aromatic dihydroxy compound may be used, or two or more types of aromatic dihydroxy compounds may be used in any combination and ratio.

Among the monomers that are the raw materials for polycarbonate resin (A), examples of carbonate precursors include carbonyl halides and carbonate esters. As the raw material for polycarbonate resin (A), one type of carbonate precursor may be used, or two or more types of carbonate precursors may be used in any combination and ratio.

Among the above carbonate precursors, examples of carbonyl halides include haloformates such as bischloroformates obtained by reacting phosgene with a dihydroxy compound, and monochloroformates of dihydroxy compounds.

Examples of carbonate esters include diaryl carbonates, dialkyl carbonates, and carbonates of dihydroxy compounds. Examples of diaryl carbonates include diphenyl carbonate and ditolyl carbonate. Examples of dialkyl carbonates include dimethyl carbonate and diethyl carbonate. Examples of carbonates of dihydroxy compounds include biscarbonates of dihydroxy compounds, monocarbonates of dihydroxy compounds, and cyclic carbonates.

The method for producing the polycarbonate resin (A) is not particularly limited, and any method can be used. For example, examples of methods for producing the polycarbonate resin (A) include the interfacial polymerization method, the melt transesterification method, the pyridine method, the ring-opening polymerization method of a cyclic carbonate compound, and the solid-phase transesterification method of a prepolymer. Among these, the interfacial polymerization method is particularly preferred.

The molecular weight of the polycarbonate resin (A) is preferably 10,000 to 26,000 in terms of viscosity average molecular weight (Mv) calculated from the solution viscosity measured at 25°C using methylene chloride as a solvent. The lower limit of the viscosity average molecular weight (Mv) of this polycarbonate resin (A) is more preferably 10,500 or more, even more preferably 11,000 or more, particularly preferably 11,500 or more, and most preferably 12,000 or more. The upper limit of the viscosity average molecular weight (Mv) of this polycarbonate resin (A) is more preferably 24,000 or less, even more preferably 20,000 or less. By making the viscosity average molecular weight (Mv) of the polycarbonate resin (A) 10,000 or more, the mechanical strength of the polycarbonate resin composition of the present invention can be further improved. By setting the viscosity average molecular weight (Mv) of the polycarbonate resin (A) to 26,000 or less, it is possible to suppress a decrease in the fluidity of the polycarbonate resin composition of the present invention and improve the fluidity of the polycarbonate resin composition (ensuring high fluidity). As a result, the molding processability of the polycarbonate resin composition is improved, making it easier to perform thin-wall molding.

The polycarbonate resin (A) may be a mixture of two or more polycarbonate resins with different viscosity average molecular weights. In this case, as long as the viscosity average molecular weight of the polycarbonate resin (A) is within the range of 10,000 to 26,000, the polycarbonate resin (A) may contain a polycarbonate resin with a viscosity average molecular weight outside the range of 10,000 to 26,000.

In the present invention, the viscosity average molecular weight (Mv) means a value calculated from the Schnell viscosity formula, i.e., η = 1.23 × 10 ^-4 Mv ^0.83 , by measuring the intrinsic viscosity [η] (unit: dl/g) at 25°C using methylene chloride as a solvent and an Ubbelohde viscometer. The intrinsic viscosity [η] is a value calculated from the specific viscosity [η _sp ] at each solution concentration [c] (g/dl) and the following formula:

The terminal hydroxyl group concentration of the polycarbonate resin (A) is arbitrary and may be appropriately selected and determined. For example, the terminal hydroxyl group concentration of the polycarbonate resin (A) is 1000 ppm or less, preferably 800 ppm or less, and more preferably 600 ppm or less. By setting the upper limit of the terminal hydroxyl group concentration in this way, the residence thermal stability and color tone of the polycarbonate resin (A) can be further improved. In addition, the lower limit of the terminal hydroxyl group concentration of the polycarbonate resin (A) is 10 ppm or more, preferably 30 ppm or more, and more preferably 40 ppm or more, particularly when the polycarbonate resin (A) is produced by a melt transesterification method. By setting the lower limit of the terminal hydroxyl group concentration in this way, the decrease in the molecular weight of the polycarbonate resin (A) can be suppressed, and the mechanical properties of the polycarbonate resin composition containing the polycarbonate resin (A) can be further improved.

The unit of the terminal hydroxyl group concentration of polycarbonate resin (A) is the mass of terminal hydroxyl groups relative to the mass of the polycarbonate resin (A) expressed in ppm. The method for measuring the terminal hydroxyl group concentration is colorimetric determination using the titanium tetrachloride/acetic acid method (the method described in Macromol. Chem. 88 215 (1965)).

In addition, in order to improve the appearance of a molded article made of the polycarbonate resin composition of the present invention and to improve the flowability of the polycarbonate resin composition, the polycarbonate resin (A) may contain a polycarbonate oligomer. The viscosity average molecular weight (Mv) of this polycarbonate oligomer is, for example, 1500 or more, and preferably 2000 or more. The upper limit of the viscosity average molecular weight (Mv) of this polycarbonate oligomer is, for example, 9500 or less, and preferably 9000 or less. Furthermore, the content of this polycarbonate oligomer is preferably 30 mass% or less of the polycarbonate resin (A) containing the polycarbonate oligomer.

Furthermore, polycarbonate resin (A) may contain not only virgin raw materials but also polycarbonate resin recycled from used products (so-called material recycled polycarbonate resin) as one of the raw material components. However, the content of the recycled polycarbonate resin is preferably 80 mass% or less of the polycarbonate resin (A), and particularly preferably 50 mass% or less. This is because recycled polycarbonate resin is likely to have been deteriorated by heat degradation, aging, etc., and if the content of such recycled polycarbonate resin is more than 80 mass%, the color and mechanical properties of the polycarbonate resin composition containing polycarbonate resin (A) may be deteriorated.

[Phosphorus-based stabilizer (C)]
Next, the phosphorus-based stabilizer (C) applied to the polycarbonate resin composition according to the embodiment of the present invention will be described in detail. The polycarbonate resin composition may further contain the phosphorus-based stabilizer (C) in addition to the above-mentioned polycarbonate resin (A) and polyether polycarbonate resin (B). By containing this phosphorus-based stabilizer (C), the polycarbonate resin composition has a better hue and has better heat discoloration resistance.

Any known phosphorus-based stabilizer (C) can be used. For example, phosphorus-based stabilizers (C) include phosphorus oxoacids, acid pyrophosphate metal salts, phosphate salts of Group 1 or Group 2B metals, phosphate compounds, phosphite compounds, phosphonite compounds, and the like. Among these, phosphite compounds are particularly preferred as the phosphorus-based stabilizer (C). By selecting a phosphite compound as the phosphorus-based stabilizer (C), a polycarbonate resin composition having higher heat discoloration resistance and continuous productivity can be obtained.

Examples of phosphorus oxoacids include phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, polyphosphoric acid, etc. Examples of metal acid pyrophosphates include sodium acid pyrophosphate, potassium acid pyrophosphate, calcium acid pyrophosphate, etc. Examples of phosphates of Group 1 or Group 2B metals include potassium phosphate, sodium phosphate, cesium phosphate, zinc phosphate, etc.

Here, the phosphite compound is a trivalent phosphorus compound represented by the general formula: P(OR) ₃ . In this general formula, R represents a monovalent or divalent organic group. Examples of such phosphite compounds include triphenyl phosphite, tris(mononylphenyl)phosphite, tris(mononyl/dinonyl-phenyl)phosphite, tris(2,4-di-tert-butylphenyl)phosphite, monooctyldiphenyl phosphite, dioctylmonophenyl phosphite, monodecyldiphenyl phosphite, didecylmonophenyl phosphite, tridecyl phosphite, trilauryl phosphite, tristearyl phosphite, distearyl pentaerythritol diphosphite, bis(2,4- di-tert-butyl-4-methylphenyl)pentaerythritol phosphite, bis(2,6-di-tert-butylphenyl)octyl phosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl)octyl phosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene-diphosphite, 6-[3-(3-tert-butyl-hydroxy-5-methylphenyl)propoxy]-2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]-dioxaphosphepine, and the like.

Among the above-mentioned phosphite compounds, the aromatic phosphite compounds represented by the following general formula (5) or general formula (6) are particularly effective in improving the heat discoloration resistance of the polycarbonate resin composition of the present invention, and are therefore more preferred.

In formula (5), R ¹ , R ² and R ³ may be the same or different and each represents an aryl group having 6 to 30 carbon atoms.

In formula (6), R ⁴ and R ⁵ may be the same or different and each represents an aryl group having 6 to 30 carbon atoms.

As examples of aromatic phosphite compounds represented by the above general formula (5), triphenyl phosphite, tris(mononylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, etc. are preferred, and among these, tris(2,4-di-tert-butylphenyl) phosphite is more preferred. Specific examples of such aromatic phosphite compounds include "Adeka STAB 1178" manufactured by ADEKA Corporation, "Sumilizer TNP" manufactured by Sumitomo Chemical Co., Ltd., "JP-351" manufactured by Johoku Chemical Industry Co., Ltd., "Adeka STAB 2112" manufactured by ADEKA Corporation, "Irgafos 168" manufactured by BASF, "JP-650" manufactured by Johoku Chemical Industry Co., Ltd., etc.

As the aromatic phosphite compound represented by the above general formula (6), for example, those having a pentaerythritol diphosphite structure such as bis(2,4-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, etc. are particularly preferred. Specific examples of preferred aromatic phosphite compounds include "ADEKA STAB PEP-24G" and "ADEKA STAB PEP-36" manufactured by ADEKA Corporation, and "Doverphos S-9228" manufactured by Doverchemical Corporation.

Among the above-mentioned phosphite compounds, the aromatic phosphite compound represented by the general formula (6) is particularly preferred as the phosphorus-based stabilizer (C). This is because the inclusion of the aromatic phosphite compound provides the polycarbonate resin composition of the present invention with a more excellent hue.

The polycarbonate resin composition of the present invention may contain one type of phosphorus-based stabilizer (C), or may contain two or more types of phosphorus-based stabilizers (C) in any combination and ratio.

When the polycarbonate resin composition of the present invention contains a phosphorus-based stabilizer (C), the content of this phosphorus-based stabilizer (C) is 0.005 to 0.5 parts by mass per 100 parts by mass of the polycarbonate resin (A) in the polycarbonate resin composition. The lower limit of the content of this phosphorus-based stabilizer (C) is preferably 0.007 parts by mass or more, more preferably 0.008 parts by mass or more, and particularly preferably 0.01 parts by mass or more. The upper limit of the content of this phosphorus-based stabilizer (C) is preferably 0.4 parts by mass or less, more preferably 0.3 parts by mass or less, even more preferably 0.2 parts by mass or less, and particularly preferably 0.1 parts by mass or less.

If the content of the phosphorus-based stabilizer (C) is less than 0.005 parts by mass, the effect of improving the hue and heat discoloration resistance of the polycarbonate resin composition due to the inclusion of the phosphorus-based stabilizer (C) may not be obtained. If the content of the phosphorus-based stabilizer (C) exceeds 0.5 parts by mass, the heat discoloration resistance of the polycarbonate resin composition may worsen. Furthermore, the humidity and heat stability of the polycarbonate resin composition may decrease.

[Epoxy compound (D)]
Next, the epoxy compound (D) applied to the polycarbonate resin composition according to the embodiment of the present invention will be described in detail. The polycarbonate resin composition may further contain the epoxy compound (D) in addition to the above-mentioned polycarbonate resin (A) and polyether polycarbonate resin (B). By containing this epoxy compound (D) together with the polyether polycarbonate resin (B), the heat discoloration resistance of the polycarbonate resin composition can be further improved.

As the epoxy compound (D), for example, a compound having one or more epoxy groups in one molecule is used. Preferred examples of such epoxy compounds (D) include phenyl glycidyl ether, allyl glycidyl ether, t-butylphenyl glycidyl ether, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexyl carboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-3',4'-epoxy-6'-methylcyclohexyl carboxylate, 2,3-epoxycyclohexylmethyl-3',4'-epoxycyclohexyl carboxylate, 4-(3,4-epoxy-5-methylcyclohexyl)butyl-3',4'-epoxycyclohexyl carboxylate, , 3,4-epoxycyclohexylethylene oxide, cyclohexylmethyl 3,4-epoxycyclohexylcarboxylate, 3,4-epoxy-6-methylcyclohexylmethyl-6'-methylcyclohexylcarboxylate, bisphenol-A diglycidyl ether, tetrabromobisphenol-A glycidyl ether, diglycidyl ester of phthalic acid, diglycidyl ester of hexahydrophthalic acid, bis-epoxydicyclopentadienyl ether, bis-epoxyethylene glycol, bis-epoxycyclohexyl adipate, butadiene diepoxide, tetraphenylethylene epoxy , octyl epoxy thalate, epoxidized polybutadiene, 3,4-dimethyl-1,2-epoxycyclohexane, 3,5-dimethyl-1,2-epoxycyclohexane, 3-methyl-5-t-butyl-1,2-epoxycyclohexane, octadecyl-2,2-dimethyl-3,4-epoxycyclohexyl carboxylate, N-butyl-2,2-dimethyl-3,4-epoxycyclohexyl carboxylate, cyclohexyl-2-methyl-3,4-epoxycyclohexyl carboxylate, N-butyl-2-isopropyl-3,4-epoxy-5-methylcyclohexyl carboxylate, octadecyl Examples include ethyl-3,4-epoxycyclohexyl carboxylate, 2-ethylhexyl-3',4'-epoxycyclohexyl carboxylate, 4,6-dimethyl-2,3-epoxycyclohexyl-3',4'-epoxycyclohexyl carboxylate, 4,5-epoxy tetrahydrophthalic anhydride, 3-t-butyl-4,5-epoxy tetrahydrophthalic anhydride, diethyl 4,5-epoxy-cis-1,2-cyclohexyl dicarboxylate, di-n-butyl-3-t-butyl-4,5-epoxy-cis-1,2-cyclohexyl dicarboxylate, epoxidized soybean oil, and epoxidized linseed oil.

Among these epoxy compounds (D), alicyclic epoxy compounds are preferably used. In particular, 3,4-epoxycyclohexylmethyl-3',4'-epoxycyclohexylcarboxylate is preferred.

As the epoxy compound (D), a polyalkylene glycol derivative having an epoxy group at one or both ends can also be preferably used. In particular, a polyalkylene glycol having an epoxy group at both ends is preferred.

Specific preferred examples of the polyalkylene glycol derivatives include polyalkylene glycol derivatives containing epoxy groups in their structure, such as polyethylene glycol diglycidyl ether, poly(2-methyl)ethylene glycol diglycidyl ether, poly(2-ethyl)ethylene glycol diglycidyl ether, polytetramethylene glycol diglycidyl ether, polyethylene glycol-poly(2-methyl)ethylene glycol diglycidyl ether, polytetramethylene glycol-poly(2-methyl)ethylene glycol diglycidyl ether, and polytetramethylene glycol-poly(2-ethyl)ethylene glycol diglycidyl ether.

The polycarbonate resin composition of the present invention may contain one type of epoxy compound (D), or may contain two or more types of epoxy compounds (D) in any combination and ratio.

When the polycarbonate resin composition of the present invention contains an epoxy compound (D), the content of this epoxy compound (D) is preferably 0.0005 to 0.2 parts by mass per 100 parts by mass of the polycarbonate resin (A). The lower limit of the content of this epoxy compound (D) is preferably 0.001 parts by mass or more, more preferably 0.003 parts by mass or more, and particularly preferably 0.005 parts by mass or more. The upper limit of the content of this epoxy compound (D) is preferably 0.15 parts by mass or less, more preferably 0.1 parts by mass or less, and particularly preferably 0.05 parts by mass or less.

If the content of epoxy compound (D) is less than 0.0005 parts by mass, the effect of improving the hue and heat discoloration resistance of the polycarbonate resin composition due to the inclusion of epoxy compound (D) may not be obtained. If the content of epoxy compound (D) exceeds 0.2 parts by mass, the heat discoloration resistance of the polycarbonate resin composition may worsen. Furthermore, the hue and moist heat stability of the polycarbonate resin composition may decrease.

[Oxetane Compound (E)]
Next, the oxetane compound (E) applied to the polycarbonate resin composition according to the embodiment of the present invention will be described in detail. The polycarbonate resin composition may further contain the oxetane compound (E) in addition to the above-mentioned polycarbonate resin (A) and polyether polycarbonate resin (B). By containing this oxetane compound (E) together with the polyether polycarbonate resin (B), the heat discoloration resistance of the polycarbonate resin composition can be further improved.

As the oxetane compound (E), for example, any compound having one or more oxetane groups in the molecule can be used. In other words, both monooxetane compounds having one oxetane group in the molecule and polyoxetane compounds having two or more oxetane groups in the molecule and having two or more functionalities can be used as the oxetane compound (E). By including the oxetane compound (E), the color of the polycarbonate resin composition of the present invention can be improved and the heat discoloration resistance can be further improved.

Specific preferred examples of monooxetane compounds include compounds represented by the following general formula (III-a), compounds represented by general formula (III-b), and compounds represented by general formula (IV).

In general formula (III-a), general formula (III-b) and general formula (IV), R ¹ represents an alkyl group. In general formula (III-b), R ² represents an alkyl group or a phenyl group. In general formula (IV), R ³ represents a divalent organic group. This divalent organic group represented by R ³ may or may not have an aromatic ring. In general formula (IV), n is 0 or 1.

In addition, in the general formulae (III-a), (III-b) and (IV), R ¹ is an alkyl group as described above, and is preferably an alkyl group having 1 to 6 carbon atoms, more preferably a methyl group or an ethyl group, and particularly preferably an ethyl group.

In addition, in the general formula (III-b), R ² is an alkyl group or a phenyl group as described above, but is preferably an alkyl group having 2 to 10 carbon atoms. The alkyl group having 2 to 10 carbon atoms may be any of a linear alkyl group, a branched alkyl group, and an alicyclic alkyl group, and may be a linear or branched alkyl group having an ether bond (ether-based oxygen atom) in the middle of the alkyl chain. Specific examples of R ² include an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, a 2-ethylhexyl group, a nonyl group, a decyl group, a 3-oxypentyl group, a cyclohexyl group, and a phenyl group. Among these, R ² is preferably a 2-ethylhexyl group, a phenyl group, or a cyclohexyl group.

Preferred specific examples of the compound represented by general formula (III-a) include 3-hydroxymethyl-3-methyloxetane, 3-hydroxymethyl-3-ethyloxetane, 3-hydroxymethyl-3-propyloxetane, 3-hydroxymethyl-3-n-butyloxetane, and 3-hydroxymethyl-3-propyloxetane. Among these, 3-hydroxymethyl-3-methyloxetane and 3-hydroxymethyl-3-ethyloxetane are particularly preferred. Furthermore, a specific example of the compound represented by general formula (III-b) is 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane, and the like.

In general formula (IV), R ³ is a divalent organic group which may or may not have an aromatic ring, as described above. Specific examples of R ³ include linear or branched alkylene groups having 1 to 12 carbon atoms, such as ethylene, propylene, butylene, neopentylene, n-pentamethylene, and n-hexamethylene, phenylene, divalent groups represented by the formula -CH ₂ -Ph-CH ₂ - or -CH ₂ -Ph-Ph-CH ₂ - (wherein Ph represents a phenyl group), hydrogenated bisphenol A residue, hydrogenated bisphenol F residue, hydrogenated bisphenol Z residue, cyclohexanedimethanol residue, and tricyclodecanedimethanol residue.

Specific examples of particularly preferred compounds represented by general formula (IV) include bis(3-methyl-3-oxetanylmethyl)ether, bis(3-ethyl-3-oxetanylmethyl)ether, bis(3-propyl-3-oxetanylmethyl)ether, bis(3-butyl-3-oxetanylmethyl)ether, 1,4-bis[(3-ethyl-3-oxetanylmethoxy)methyl]benzene, 3-ethyl-3{[(3-ethyloxetan-3-yl)methoxy]methyl}oxetane, 4,4'-bis[(3-ethyl-3-oxetanyl)methoxymethyl]biphenyl, and 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene.

The polycarbonate resin composition of the present invention may contain one type of oxetane compound (E), or may contain two or more types of oxetane compounds (E) in any combination and ratio.

When the polycarbonate resin composition of the present invention contains an oxetane compound (E), the preferred content of the oxetane compound (E) is 0.0005 to 0.2 parts by mass per 100 parts by mass of the polycarbonate resin (A). The lower limit of the content of the oxetane compound (E) is more preferably 0.001 parts by mass or more, even more preferably 0.003 parts by mass or more, and particularly preferably 0.005 parts by mass or more. The upper limit of the content of the oxetane compound (E) is more preferably 0.15 parts by mass or less, even more preferably 0.1 parts by mass or less, and particularly preferably 0.05 parts by mass or less.

If the content of the oxetane compound (E) is less than 0.0005 parts by mass, the effect of improving the hue and heat discoloration resistance of the polycarbonate resin composition by containing the oxetane compound (E) may not be obtained. If the content of the oxetane compound (E) exceeds 0.2 parts by mass, the heat discoloration resistance of the polycarbonate resin composition may actually deteriorate.

It is also preferable that the polycarbonate resin composition of the present invention contains both the above-mentioned epoxy compound (D) and oxetane compound (E). In this case, the total content of the epoxy compound (D) and the oxetane compound (E) is preferably 0.0005 to 0.2 parts by mass per 100 parts by mass of the polycarbonate resin (A).

[Additives, etc.]
Next, additives and the like applied to the polycarbonate resin composition according to the embodiment of the present invention will be described in detail. The polycarbonate resin composition may contain other additives in addition to the above-mentioned components such as the polycarbonate resin (A) and the polyether polycarbonate resin (B). Examples of the additives include antioxidants, release agents, ultraviolet absorbers, fluorescent whitening agents, pigments, dyes, polymers other than polycarbonate resins, flame retardants, impact resistance improvers, antistatic agents, plasticizers, and compatibilizers. Examples of the polymers other than the polycarbonate resins include polyalkylene glycols. The polyalkylene glycols that may be contained in the polycarbonate resin composition have the same structure as the polyalkylene glycols constituting the above-mentioned polyether polycarbonate resin (B). The polycarbonate resin composition may contain one type of additive among these additives, or may contain an additive containing two or more types of additives.

However, when the polycarbonate resin composition of the present invention contains other polymers other than the polycarbonate resin (A) and the polyether polycarbonate resin (B), the content of the other polymers is preferably 20 parts by mass or less, more preferably 10 parts by mass or less, even more preferably 5 parts by mass or less, and particularly preferably 3 parts by mass or less, per 100 parts by mass of the total of the polycarbonate resin (A) and the polyether polycarbonate resin (B).

[Yellowing index and yellowing index of polycarbonate resin composition]
Next, the yellowness and yellowing index of the polycarbonate resin composition according to the embodiment of the present invention will be described. Yellowness index (YI) is an index representing the degree of the hue of the polycarbonate resin composition. For example, the hue of the polycarbonate resin composition is represented by the initial value of yellowness (hereinafter referred to as the initial YI value). The initial YI value is the YI value of the polycarbonate resin composition in the initial state before deterioration due to load such as heat or deterioration over time occurs. The yellowing index ΔYI is an index representing the heat discoloration resistance of the polycarbonate resin composition. The yellowing index ΔYI is represented by the difference between the YI value of the polycarbonate resin composition after being held under a predetermined temperature and time condition and the initial YI value.

The initial YI value and the yellowing index ΔYI each have a value equal to or less than a preset threshold value. For example, when light from a light source passes through a 300 mm optical path in a polycarbonate resin composition, the threshold value of the initial YI value is set to 25.0, and the threshold value of the yellowing index ΔYI is set to 6.0. The initial YI value of the polycarbonate resin composition of the present invention at an optical path length of 300 mm is preferably 25.0 or less. Furthermore, the difference between the YI value of the polycarbonate resin composition at an optical path length of 300 mm after a specified accelerated deterioration test and the initial YI value, i.e., the yellowing index ΔYI, is preferably 6.0 or less, more preferably 5.5 or less. An example of the accelerated deterioration test is one in which the polycarbonate resin composition is held at a temperature of 95° C. for 250 hours.

When the initial YI value exceeds 25.0, the light (transmitted light) after passing through a light path of 300 mm in the polycarbonate resin composition in the initial state is yellowed to an extent that exceeds the allowable hue change for the polycarbonate resin composition (for example, to an extent that can be confirmed by visual inspection) compared to the light emitted from the light source. Also, when the yellowing degree ΔYI exceeds 6.0, the light that has passed through a light path of 300 mm in the polycarbonate resin composition after the accelerated aging test is yellowed to an extent that exceeds the allowable hue change for the polycarbonate resin composition compared to the transmitted light having the hue represented by the initial YI value.

[Method for producing polycarbonate resin composition]
Next, a method for producing a polycarbonate resin composition according to an embodiment of the present invention will be described in detail. The method for producing the polycarbonate resin composition is not particularly limited, and a method for producing a polycarbonate resin composition known in the art can be widely adopted. In one example of the production method, the polycarbonate resin (A) and the polyether polycarbonate resin (B) are mixed in advance using various mixers such as a tumbler or a Henschel mixer, with other components that are mixed as necessary. Examples of the other components include the phosphorus-based stabilizer (C), the epoxy compound (D), the oxetane compound (E), and additives. After mixing the components in this manner, the resulting mixture is melt-kneaded with a mixer such as a Banbury mixer, a roll, a Brabender, a single-screw kneading extruder, a twin-screw kneading extruder, or a kneader, to obtain the polycarbonate resin composition of the present invention. The temperature of the melt-kneading of the mixture is not particularly limited, but is, for example, within the range of 240 to 320°C.

[Molded products]
Next, a molded article of the polycarbonate resin composition according to the embodiment of the present invention will be described in detail. The molded article of the present invention is a molded article made of the polycarbonate resin composition according to the embodiment described above, and can be produced, for example, by pelletizing the polycarbonate resin composition and molding the pellets obtained by various molding methods. The molded article of the present invention may also be produced by directly molding the polycarbonate resin composition melt-kneaded in an extruder, without going through the above-mentioned pellets.

The molded article produced by the above molding method is made of the polycarbonate resin composition of the present invention, and therefore has a good hue, excellent heat discoloration resistance, and excellent transparency. Examples of such molded articles include optical parts such as light guide plates. The hue and heat discoloration resistance of the molded article are expressed by the initial YI value and the yellowing index ΔYI, respectively, as with the above-mentioned polycarbonate resin composition. That is, the initial YI value of the molded article at an optical path length of 300 mm is preferably 25.0 or less, and the yellowing index ΔYI of the molded article at an optical path length of 300 mm is preferably 6.0 or less, and more preferably 5.5 or less.

As explained above, the polycarbonate resin composition of the present invention has high fluidity and good hue, and can also have excellent transparency. Therefore, molded products such as optical parts that enjoy the effects of the polycarbonate resin composition can be easily obtained by a desired molding method such as injection molding. In particular, the polycarbonate resin composition of the present invention is suitable for use in molding thin-walled, large optical parts.

In addition, the resin temperature during injection molding is preferably higher than 260 to 300°C, which is the temperature generally applied to injection molding of polycarbonate resin, particularly when producing large thin-walled molded products, and is preferably, for example, 305 to 400°C. The lower limit of this resin temperature is more preferably 310°C or higher, even more preferably 315°C or higher, and particularly preferably 320°C or higher. The upper limit of this resin temperature is more preferably 390°C or lower. When using conventional polycarbonate resin compositions, there was a problem that when the resin temperature during molding was increased to mold a large thin-walled molded product, the resulting molded product was prone to yellowing. In contrast, by using the polycarbonate resin composition of the present invention, it is possible to produce molded products, particularly large and thin-walled optical parts, that have good hue and excellent transparency even in the above temperature range. Note that when it is difficult to directly measure the above resin temperature, the barrel setting temperature during molding is used as the above resin temperature.

Here, a large thin-walled molded product refers to a molded product having a plate-shaped part with a wall thickness of 1 mm or less, preferably 0.8 mm or less, more preferably 0.6 mm or less, and a dimension such as a vertical or horizontal length or diameter corresponding to the optical path length of 100 mm or more. The plate-shaped part may be flat or curved. The surface of the plate-shaped part may be flat or may have irregularities. The cross section of the plate-shaped part may have an inclined surface or may be a wedge-shaped cross section, etc.

The optical components of the present invention include parts of devices and instruments that directly or indirectly use light sources such as LEDs (Light Emitting Diodes), organic EL (Electro Luminescence), incandescent bulbs, fluorescent lamps, and cathode tubes. Representative examples of such optical components include light guide plates and surface light emitter members. Light guide plates are used to guide light from light sources such as LEDs in liquid crystal backlight units and various display devices and lighting devices. For example, light guide plates usually diffuse light received from the side or back side, etc., using unevenness provided on the surface, and emit uniform light. In general, the shape of the light guide plate is flat. The surface of the light guide plate may or may not have unevenness. In addition, the light guide plate is preferably molded by a molding method such as injection molding, ultra-high speed injection molding, injection compression molding, or melt extrusion molding (e.g., T-die molding).

The light guide plate molded using the polycarbonate resin composition of the present invention has good hue and excellent transparency without cloudiness or loss of transmittance. The light guide plate can be suitably used in the fields of liquid crystal backlight units, various display devices, and lighting devices. Examples of devices to which such light guide plates are applied include various portable terminals such as mobile phones, mobile notebooks, netbooks, slate PCs (personal computers), tablet PCs, smartphones, and tablet terminals, cameras, watches, desktop or laptop (notebook) PCs, various displays, lighting equipment, etc.

In addition, the shape of the optical component molded using the polycarbonate resin composition of the present invention may be either a film or a sheet. Specific examples of such optical components include light-guiding films.

In addition to the light guide plates described above, the optical components of the present invention can also be suitably used as light guides or lenses that guide light from light sources such as LEDs in vehicle lighting devices such as headlamps, rear lamps, or fog lamps for automobiles and motorcycles.

The present invention will be described in more detail below with reference to examples. Note that the present invention should not be construed as being limited to the following examples.

(Examples 1 to 14, Comparative Examples 1 to 3)
[Components of polycarbonate resin composition]
The components of the polycarbonate resin composition in each of Examples 1 to 14 and Comparative Examples 1 to 3 are as shown in Table 1. In each of Examples 1 to 14 and Comparative Examples 1 to 3, the polycarbonate resin (A), polyether polycarbonate resin (B), polyalkylene glycol (X), phosphorus-based stabilizer (C), and epoxy compound (D) shown in Table 1 are used as necessary.

As the polycarbonate resin (A), polycarbonate resin (A1) is used. As the polyether polycarbonate resin (B), polyether polycarbonate resin (B1), polyether polycarbonate resin (B2) or polyether polycarbonate resin (B3) is used. As the polyalkylene glycol (X), polyalkylene glycol (X1) is used. As the phosphorus-based stabilizer (C), phosphorus-based stabilizer (C1) is used. As the epoxy compound (D), epoxy compound (D1) is used.

[Method for producing pellets of polycarbonate resin composition]
In each of Examples 1 to 14 and Comparative Examples 1 to 3, the components shown in Table 1 above were blended in the ratios (parts by mass) shown in Tables 2-1 to 2-3 below, and mixed in a tumbler for 20 minutes. Next, using a vented single-screw extruder with a screw diameter of 40 mm ("VS-40" manufactured by Tanabe Plastic Machinery Co., Ltd.), the cylinder temperature was set to 240°C, and the mixture of the components above was melt-kneaded, thereby producing a polycarbonate resin composition. Thereafter, strands of this polycarbonate resin composition were extruded, and the extruded strands were cut (pelletized) to obtain pellets of this polycarbonate resin composition.

[Strand Transparency Evaluation]
In each of Examples 1 to 14 and Comparative Examples 1 to 3, a strand transparency evaluation was performed on the strand obtained during the production of pellets of the polycarbonate resin composition. In detail, the transparency of the strand extruded from the extruder in the above-mentioned production process of pellets of the polycarbonate resin composition was visually judged based on the following evaluation criteria.
<Evaluation criteria>
A: The extruded strands have extremely high transparency, and the compatibility of the polycarbonate resin (A) with the polyether polycarbonate resin (B) and the polyalkylene glycol is extremely good.
B: The extruded strands have high transparency and the compatibility of the polycarbonate resin (A) with the polyether polycarbonate resin (B) and the polyalkylene glycol is good.
C: The extruded strands were cloudy and the compatibility of the polycarbonate resin (A) with the polyether polycarbonate resin (B) or with the polyalkylene glycol was poor.
D: The extruded strands were significantly cloudy, and the compatibility of the polycarbonate resin (A) with the polyether polycarbonate resin (B) or the polyalkylene glycol was extremely poor.

[Evaluation of color and heat discoloration resistance]
In each of Examples 1 to 14 and Comparative Examples 1 to 3, the hue and heat discoloration resistance of the optical path made of the polycarbonate resin composition were evaluated. In detail, the pellets obtained by the above manufacturing method were dried at 120°C for 5 to 7 hours by a hot air circulation dryer, and then supplied to an injection molding machine (Sodick's "HSP100A"), and the polycarbonate resin composition was injection molded by this injection molding machine to form a long optical path molded product. The conditions during this injection molding were a resin temperature (cylinder temperature) of 340°C and a mold temperature of 80°C. The obtained long optical path molded product was made of a polycarbonate resin composition and had an optical path length of 300 mm. The size of this long optical path molded product was length x width x thickness = 300 mm x 7 mm x 4 mm.

In the evaluation of the hue, the initial YI value, which is an index that can judge the quality of the hue of the polycarbonate resin composition, was measured. Specifically, the initial YI value was measured at an optical path length of 300 mm for the above-mentioned long optical path molded product. The initial YI value can be measured by transmitting light through the optical path (optical path length: 300 mm) of the long optical path molded product, receiving the transmitted light at the light receiving section under the geometric condition e (0°:0°) of light receiving conforming to JIS Z 8722, and measuring the YI calculated in conformity with ASTM D 1925. A long optical path spectrophotometer ("ASA 1" manufactured by Nippon Denshoku Industries Co., Ltd., C light source, 2° field of view) was used to measure the initial YI value.

In the evaluation of heat discoloration resistance, the yellowing index ΔYI was derived, which is an index that can judge the quality of the heat discoloration resistance of a polycarbonate resin composition. Specifically, the long optical path molded product for which the initial YI value was measured was kept in a high-temperature environment of 95°C for 250 hours, and then the YI value of the long optical path molded product at an optical path length of 300 mm was measured, and the yellowing index ΔYI, which is the difference between the obtained YI value and the initial YI value, was obtained. The YI value in the evaluation of heat discoloration resistance can be measured in the same manner as the initial YI value described above, except that the measurement subject is the long optical path molded product after being kept in a high-temperature environment.

The content ratio (parts by mass) of each component of the polycarbonate resin composition in each of Examples 1 to 14 and Comparative Examples 1 to 3 and the results of each of the above evaluations are shown in Tables 2-1 to 2-3. In Tables 2-1 to 2-3, "YI (300 mm)" means the initial YI value at an optical path length of 300 mm, and "ΔYI (300 mm)" means the yellowing degree ΔYI at an optical path length of 300 mm.

As shown in Tables 2-1 and 2-2, the strand transparency evaluation results were "A" in all Examples 1 to 14. In other words, the compatibility between the polycarbonate resin (A) and the polyether polycarbonate resin (B) was extremely good in all Examples 1 to 14.

In addition, in Examples 1 to 14, the initial YI value and yellowing index ΔYI of the polycarbonate resin composition at an optical path length of 300 mm were the values shown in Tables 2-1 and 2-2. In detail, in all of Examples 1 to 14, the initial YI value was a value equal to or less than the threshold value of the initial YI value (=25.0) when the target optical path length was 300 mm, and the yellowing index ΔYI was a value equal to or less than the threshold value of the yellowing index ΔYI when the target optical path length was 300 mm (=6.0). From these results, it was confirmed that the initial hue was good and the heat discoloration resistance was also excellent in all of the polycarbonate resin compositions in Examples 1 to 14.

On the other hand, as shown in Table 2-3, the strand transparency evaluation results were good in Comparative Example 1, but poor in Comparative Examples 2 and 3. In Comparative Example 1, the initial YI value at an optical path length of 300 mm exceeded the threshold value, and the initial hue was poor. In Comparative Example 2, the initial YI value at an optical path length of 300 mm was below the threshold value, but the yellowing index ΔYI at an optical path length of 300 mm exceeded the threshold value, and the heat discoloration resistance was poor. In Comparative Example 3, the optical path itself made of the polycarbonate resin composition became cloudy, and the initial YI value and yellowing index ΔYI could not be obtained.

The present invention is not limited to the above-described embodiment and examples, and the present invention also includes configurations in which the above-described components are appropriately combined. In addition, other embodiments, examples, and operational techniques made by those skilled in the art based on the above-described embodiment are all included in the scope of the present invention.

The polycarbonate resin composition of the present invention has high fluidity, good color, and excellent transparency, making it highly suitable for use in various molded products, particularly optical components such as light guide plates.

Claims (6)

The composition contains 0.01 to 5 parts by mass of a polyether polycarbonate resin (B) having a polyether and a carbonate bond per 100 parts by mass of the polycarbonate resin (A),
The polyether polycarbonate resin (B) is a copolymer represented by the following general formula (1):
The weight average molecular weight (Mw) of the polyether polycarbonate resin (B) is 1,000 or more and less than 8,000 in terms of polystyrene measured by gel permeation chromatography using chloroform as a solvent.
A polycarbonate resin composition comprising:

(In general formula (1), R _Z and R _X each independently represent a hydrogen atom or an alkyl group having 1 to 3 carbon atoms. There are a plurality of R _Z and R _X , and the plurality of R _Z and R _X may be the same or different. i represents an integer of 2 to 10, p represents an integer of 1 to 600, and n represents an integer of 1 to 3000.) In the general formula (1), i is 3 or 4.
The polycarbonate resin composition according to claim 1 . The composition further contains 0.005 to 0.5 parts by mass of a phosphorus-based stabilizer (C) relative to 100 parts by mass of the polycarbonate resin (A).
The polycarbonate resin composition according to claim 1 or 2 . The initial YI value of the polycarbonate resin composition at an optical path length of 300 mm is 25.0 or less,
The difference ΔYI between the YI value at an optical path length of 300 mm of the polycarbonate resin composition after being held at 95° C. for 250 hours and the initial YI value is 6.0 or less.
The polycarbonate resin composition according to any one of claims 1 to 3 . A polycarbonate resin composition according to any one of claims 1 to 4 .
A molded article characterized by: Optical components,
6. The molded article according to claim 5 .