JP2024047406A - Aromatic polycarbonate resin composition and light-diffusing molded article - Google Patents

Abstract

[Problem] To provide an aromatic polycarbonate resin composition which does not impair the inherent properties of polycarbonate resin such as heat resistance and mechanical strength, has excellent thermal stability, is high in transparency, light transmittance and light diffusion, and is resistant to deterioration in transparency and light transmittance. [Solution] The aromatic polycarbonate resin composition contains a linear aromatic polycarbonate resin (A), a fatty acid ester (B), a light diffusing agent (C), a phosphorus-based antioxidant (D) and an aromatic compound (E) represented by the following formula (1), and contains 0.1 to 2.0 parts by weight of the fatty acid ester (B), 0.1 to 10 parts by weight of the light diffusing agent (C), up to 0.005 to 0.5 parts by weight of the phosphorus-based antioxidant (D), and up to 0.003 part by weight of the aromatic compound (E) relative to 100 parts by weight of the linear aromatic polycarbonate resin (A). Formula (1): [Chemical formula 1] TIFF2024047406000015.tif2846 [Selected figure] None

Description

The present invention relates to an aromatic polycarbonate resin composition and a light-diffusing molded article.

Polycarbonate resin has excellent impact resistance, heat resistance, transparency, etc., and has been used in molded products such as light guide plates, various lenses, and nameplates. Light-diffusing molded products made of resin compositions in which an aromatic polycarbonate resin is blended with a light-diffusing agent such as inorganic fine particles or polymer fine particles have excellent heat resistance and dimensional stability compared to light-diffusing molded products made of acrylic resin, and are therefore used in a wide range of fields, such as electric light covers, meters, signs (especially internally illuminated), plastic window glass, light-diffusing plates for image readers or image display devices (e.g., light-diffusing plates used in backlight modules of liquid crystal display devices, light-diffusing plates used in projection display screens of projector televisions, etc.), and light-diffusing films (e.g., high-transmittance light-diffusing films used to improve the brightness of liquid crystal display devices, etc.).

In recent years, image display devices have become larger, thinner (lighter), more complex in shape, and have higher performance. As a result, there is an increasing demand for light diffusing molded products, particularly the light diffusing plates and films used in image display devices, to be larger, thinner (lighter), more complex in shape, and have higher performance. This has created a demand for aromatic polycarbonate-based resin compositions that have excellent fluidity during molding.

Patent Document 1 describes how a pentaerythritol-based ester compound is added to an aromatic polycarbonate-based resin to reduce its molecular weight through ester exchange, thereby improving its fluidity.

International Publication No. 2013/011977

However, the polycarbonate resin composition disclosed in Patent Document 1 does not fully satisfy the requirements for materials in recent years, such as minimal loss in transparency and light transmittance even when processed at high temperatures to produce thin-walled products, and the ability to produce large-sized products.

Furthermore, in recent years, there has been a demand for light-diffusing molded products (e.g., light-diffusing plates for image display devices) used in thin molded vehicle-mounted image display devices with a size of about 0.3 mm that do not lose much transparency or light transmittance even when exposed to high-temperature conditions such as light irradiation for an extremely long period of time. In other words, there is a demand for highly light-diffusing materials that do not lose light transmittance even when large, yet do not allow the light source to be seen through.

The present invention aims to provide an aromatic polycarbonate resin composition that does not impair the inherent properties of polycarbonate resin, such as heat resistance and mechanical strength, has excellent thermal stability, is highly transparent, has high light transmittance and light diffusion properties, and is unlikely to lose transparency and light transmittance (is unlikely to become cloudy or discolored) even when a large, thin molded product of about 0.3 mm (e.g., a light diffusion plate for an image display device) is exposed to high temperature conditions such as light irradiation for an extremely long period of time. In other words, the composition does not lose light transmittance even when it is large, and yet has high light diffusion properties that prevent the light source from being seen through it.

As a result of intensive research conducted by the present inventors to solve the above problems, it was discovered that an aromatic polycarbonate resin composition containing a linear aromatic polycarbonate resin, a fatty acid ester (B), a light diffusing agent (C), a phosphorus-based antioxidant (D), and, if necessary, a predetermined amount of an aromatic compound (E) represented by the following formula (1) can be obtained, which has excellent thermal stability and high light transmittance without impairing the inherent properties of polycarbonate resin, such as heat resistance and mechanical strength, and furthermore, even when a molded thin molded product (light guide plate) having a thickness of about 0.3 mm is exposed to high temperature conditions such as irradiation by a light source for a long period of time, the transparency and transmittance are not significantly reduced (opacity or coloring is unlikely to occur), i.e., a polycarbonate with high light diffusivity that does not reduce light transmittance and yet does not allow the light source to be seen through can be obtained, and the present invention has been completed.

That is, the present invention provides an aromatic polycarbonate resin composition comprising a linear aromatic polycarbonate resin (A), a fatty acid ester (B), a light diffusing agent (C), a phosphorus-based antioxidant (D), and an aromatic compound (E) represented by the following formula (1), in which the aromatic polycarbonate resin composition contains 0.01 to 0.5 parts by weight of the fatty acid ester (B), 0.1 to 6 parts by weight of the light diffusing agent (C), 0.005 to 0.5 parts by weight of the phosphorus-based antioxidant (D), and up to 0.003 parts by weight of the aromatic compound (E) relative to 100 parts by weight of the linear aromatic polycarbonate resin (A), and a light diffusing molded article obtained by molding the aromatic polycarbonate resin composition.
Formula (1):

The polycarbonate resin composition of the present invention does not impair the inherent properties of polycarbonate resin, such as heat resistance and mechanical strength, and has excellent thermal stability, high transparency, light transmittance, and light diffusion properties. Moreover, even if the molded product obtained is exposed for a long period of time under hot weather and/or high temperature conditions due to light source irradiation, the transparency and transmittance are not likely to decrease (they are not likely to become cloudy or colored). Therefore, even if the molded product is a thin molded product (diffusion plate) with a thickness of, for example, about 0.3 mm, the hue is not likely to change and the appearance is not likely to deteriorate (deteriorate), and even if the product is exposed for a long period of time under high temperature conditions due to the external environment or light source, the transparency is not likely to decrease (they are not likely to become cloudy or colored). In other words, a polycarbonate resin composition with high light diffusion properties that does not reduce light transmittance and yet does not allow the light source to be seen through can be provided, and its industrial value is extremely high.

The following describes the embodiments in detail. However, more detailed explanations than necessary may be omitted. For example, detailed explanations of already well-known matters and duplicate explanations of substantially identical configurations may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to make it easier for those skilled in the art to understand.

The inventors provide the following explanation so that those skilled in the art can fully understand the present invention, and do not intend for it to limit the subject matter described in the claims.

The aromatic polycarbonate resin composition according to an embodiment of the present invention contains a linear aromatic polycarbonate resin (A), a fatty acid ester (B), a light diffusing agent (C), a phosphorus-based antioxidant (D), and, if necessary, a specific aromatic compound (E).

In the embodiment of the present invention, the "linear aromatic polycarbonate resin (A)" is a polycarbonate resin based on an aromatic compound, and is not particularly limited as long as the aromatic polycarbonate resin composition of the present invention can be obtained. However, branched aromatic polycarbonates are excluded from the scope of the present invention as much as possible because they reduce transparency and light transmission. Examples of linear aromatic polycarbonate resins include polymers obtained by the phosgene method in which various dihydroxy diaryl compounds are reacted with phosgene, or the ester exchange method in which a dihydroxy diaryl compound is reacted with a carbonate ester such as diphenyl carbonate. Representative examples include polycarbonate resins produced from 2,2-bis(4-hydroxyphenyl)propane (bisphenol A).

In addition to bisphenol A, the dihydroxydiaryl compounds include, for example, bis(hydroxyaryl)alkanes such as bis(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)octane, bis(4-hydroxyphenyl)phenylmethane, 2,2-bis(4-hydroxyphenyl-3-methylphenyl)propane, 1,1-bis(4-hydroxy-3-tert-butylphenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, and 2,2-bis(4-hydroxy-3,5-dichlorophenyl)propane; Examples of the cycloalkanes include bis(hydroxyaryl)cycloalkanes such as 1,1-bis(4-hydroxyphenyl)cyclohexane and bis(4-hydroxyphenyl)cyclohexane; dihydroxydiaryl ethers such as 4,4'-dihydroxydiphenyl ether and 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether; dihydroxydiaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide; dihydroxydiaryl sulfoxides such as 4,4'-dihydroxydiphenyl sulfoxide and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide; and dihydroxydiaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone and 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfone. These can be used alone or in combination. In addition to these, piperazine, dipiperidyl hydroquinone, resorcin, 4,4'-dihydroxydiphenyl, etc. can be used in combination.

The viscosity average molecular weight of the linear aromatic polycarbonate resin (A) is preferably 10,000 to 100,000, and more preferably 12,000 to 30,000. When producing such an aromatic polycarbonate resin (A), a molecular weight regulator, a catalyst, etc. can be used as necessary.

In an embodiment of the present invention, the fatty acid ester (B) acts together with a specific aromatic compound (E) described later to improve the thermal stability and light transmittance of the resulting polycarbonate resin composition without impairing the inherent properties of the resulting polycarbonate resin composition, such as heat resistance and mechanical strength. Moreover, even when a molded, thin molded product (light guide plate) having a thickness of about 0.3 mm is exposed to high-temperature conditions such as irradiation by a light source for a long period of time, the decrease in transparency (opacity or coloration is less likely to occur) can be reduced.

For example, thermal degradation (clouding or coloring) of optical molded products molded from aromatic polycarbonate resin compositions caused by long-term exposure to light from a light source (such as an LED light source) is effectively prevented. When optical molded products are exposed to harsh conditions such as under the hot sun and/or long-term exposure to light, the temperature of the surface of the molded product may increase, and thermal degradation of the aromatic polycarbonate resin (A) contained in the aromatic polycarbonate resin composition may progress little by little. Furthermore, the fatty acid ester (B) in the resin composition may gradually denature, impairing the transparency (brightness or light transmittance) expected of aromatic polycarbonate resin compositions used in ordinary optical molded products, and clouding or coloring (light to dark coloring) may occur on the surface of the molded product.

In view of this problem, the present inventors have conducted intensive research and have found that a specific aromatic compound (E) is particularly effective as a compound for inhibiting deterioration such as denaturation of the fatty acid ester (B) and the resulting discoloration, and that by adding the specific aromatic compound (E) before melt-kneading the aromatic polycarbonate resin composition, the deterioration of the fatty acid ester (B) in the molded product can be inhibited and the phenomenon of clouding or discoloration (light to dark coloration) can be reduced or alleviated.

In an embodiment of the present invention, a condensation compound of an aliphatic carboxylic acid and an alcohol can be used as the fatty acid ester (B), and there is no particular limitation as long as the resin composition targeted by the present invention can be obtained.

The aliphatic carboxylic acids include saturated or unsaturated monocarboxylic acids, dicarboxylic acids, tricarboxylic acids, etc. The aliphatic carboxylic acids also include alicyclic carboxylic acids. Among these, monocarboxylic acids and dicarboxylic acids having 6 to 36 carbon atoms are preferred, and saturated monocarboxylic acids having 6 to 36 carbon atoms are even more preferred.

Specific examples of the aliphatic carboxylic acids include palmitic acid, stearic acid, valeric acid, caproic acid, capric acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, melissic acid, tetratriacontanoic acid, montanic acid, glutaric acid, adipic acid, and azelaic acid.

The alcohols include saturated or unsaturated monohydric alcohols and polyhydric alcohols, and these alcohols may have a substituent such as a fluorine atom, a chlorine atom, a bromine atom, or an aryl group. Among these, saturated alcohols having 30 or less carbon atoms are preferred, and aliphatic saturated monohydric alcohols and aliphatic saturated polyhydric alcohols having 30 or less carbon atoms are more preferred. Note that aliphatic alcohols also include alicyclic alcohols.

Specific examples of the alcohol include octanol, decanol, dodecanol, tetradecanol, stearyl alcohol, behenyl alcohol, ethylene glycol, diethylene glycol, glycerin, pentaerythritol, 2,2-dihydroxyperfluoropropanol, neopentylene glycol, ditrimethylolpropane, and dipentaerythritol.

Specific examples of fatty acid esters (B) include, for example, behenyl behenate, octyldodecyl behenate, stearyl stearate, glycerin monopalmitate, glycerin monostearate, glycerin monooleate, glycerin distearate, glycerin tristearate, pentaerythritol monopalmitate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, pentaerythritol tetrastearate, etc., which may be used alone or in combination of two or more. Among these, stearic acid esters such as glycerin monostearate, pentaerythritol stearate, and pentaerythritol distearate are suitable, and commercially available examples include Rikemal S-100A (trade name) manufactured by Riken Vitamin Co., Ltd., Unistar H476DP ("Unistar" is a registered trademark) manufactured by NOF Corporation, and Roxiol VPG861 (trade name, manufactured by Cognis Co., Ltd.).

The amount of the fatty acid ester (B) may be, for example, 0.01 to 0.5 parts by weight, preferably 0.03 to 0.5 parts by weight, and more preferably 0.05 to 0.2 parts by weight, per 100 parts by weight of the polycarbonate resin (A). When the amount of fatty acid ester (B) is 0.01 to 0.5 parts by weight, yellowing can be further suppressed and the hue can be further improved.

In an embodiment of the present invention, the light diffusing agent (C) is not particularly limited as long as it can scatter light inside the polycarbonate resin composition, and there is no particular restriction on the chemical composition, such as polymeric or inorganic. However, when the light diffusing agent (C) is added to the linear polycarbonate resin (A) and dispersed by a known method such as melt mixing using an extruder, it is necessary that the light diffusing agent is incompatible with the matrix phase or is poorly compatible and exists as particles.

As the light diffusing agent (C), fine particles having light diffusing ability are preferred. Examples of such fine particles include inorganic fine particles and polymer fine particles. Examples of inorganic fine particles include glass filler, calcium carbonate, barium sulfate, silica, talc, mica, wollastonite, titanium oxide, etc. Of these, calcium carbonate is preferred. The shape of the inorganic fine particles is preferably granular (including irregular) or plate-like rather than fibrous. For example, in the case of glass filler, examples include glass beads, glass balloons, glass milled fibers, glass flakes, ultra-thin glass flakes (manufactured by the sol-gel method), irregular glass, etc. Similarly, various shapes can be used for other inorganic fine particles.

From the viewpoint of light diffusion, the polymer fine particles are preferably spherical, and the closer to a perfect sphere, the more preferable. Examples of organic diffusing agents include silicone-based light diffusing agents, acrylic-based light diffusing agents, silicone rubber-like elastomers, polymethylsilsesquioxane, acrylic, styrene, polyester, polyolefin, urethane, nylon, methacrylate-styrene, fluorine, norbornene, and silicone-based agents, and the like. In particular, silicone-based light diffusing agents and acrylic-based light diffusing agents, which are organic fine particles, are preferred. As the light diffusing agent, commercially available products can be used. For example, as a silicone-based light diffusing agent, "Tospearl (registered trademark) 120S" manufactured by Momentive Performance Materials Japan Co., Ltd. can be used, and as an acrylic light diffusing agent, "Ganzpearl (registered trademark) GM-0449S" and "Ganzpearl GM-0205S" manufactured by Aica Kogyo Co., Ltd. and "Chemisnow (registered trademark) KMR-3TA" manufactured by Soken Chemical Industries, Ltd. can be used.

As the light diffusing agent (C), fine particles obtained by copolymerizing a styrene monomer, a methyl methacrylate monomer, and a crosslinking agent (styrene-methyl methacrylate copolymer crosslinked fine particles) can also be suitably used. They can be obtained using general emulsion polymerization, solution polymerization, dispersion polymerization, suspension polymerization, bulk polymerization, soap-free polymerization, seed polymerization, etc. Among these polymerization methods, emulsion polymerization, dispersion polymerization, and suspension polymerization are preferred, and from the viewpoint of the physical properties of the light diffusing plate, emulsion polymerization and dispersion polymerization are particularly preferred.

The crosslinking agent used in the styrene-methyl methacrylate copolymer crosslinked microparticles may be a radically polymerizable monomer containing two or more vinyl groups. Specific examples of such crosslinking agents include divinylbenzene, ethylene glycol diacrylate, ethylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, pentaerythritol tetraacrylate, and pentaerythritol tetramethacrylate. These crosslinking agents may be used alone or in combination of two or more.

The average particle size of the styrene-methyl methacrylate copolymer crosslinked microparticles is 5 to 30 μm. A more preferred average particle size is in the range of 8 to 20 μm. If the average particle size is less than 5 μm, the surface state of the resulting light diffusion plate will maintain smoothness, resulting in insufficient light scattering and poor light diffusion. If the average particle size exceeds 30 μm, the surface state of the resulting light diffusion plate will approach smoothness, causing the light to travel straight through and transmit, resulting in reduced light scattering and poor light diffusion and light source transmission prevention, which is not preferred. Common methods for measuring the average particle size of microparticles include the Coulter method, dynamic light scattering method, and centrifugal sedimentation method.

The refractive index of the styrene-methyl methacrylate copolymer crosslinked microparticles is in the range of 1.54 to 1.57. A more preferred range is 1.55 to 1.57. If the refractive index is less than 1.54, haze may occur and light transmittance may decrease. If the refractive index exceeds 1.57, light diffusion may decrease. The refractive index can be changed by adjusting the polymerization ratio of the styrene and methyl methacrylate monomers when copolymerizing the microparticles.

Commercially available examples of styrene-methyl methacrylate copolymer crosslinked microparticles include SMX-12R (average particle size 12.3 μm, refractive index 1.56) manufactured by Sekisui Chemical Co., Ltd., and GMS-6121 (average particle size 11.3 μm, refractive index 1.56) manufactured by Guide Win Special Chemicals.

The Becke method is a common method for measuring the refractive index of styrene-methyl methacrylate copolymer crosslinked microparticles. Resin particles are placed on a glass slide, and a refractive index liquid (Cargill standard refractive index liquid, manufactured by Cargill) is dropped onto it. The resin particles and the refractive index liquid are mixed well, and a sodium lamp is irradiated from below, and the outline of the particles is observed from above. If the outline is not visible, the refractive index of the refractive index liquid and the resin particles are deemed to be equal. The absolute value of the difference between the refractive index of the light diffusing agent and the refractive index of the aromatic polycarbonate resin is preferably 0.02 to 0.2. By having the difference in refractive index within this range, it is possible to achieve both light diffusibility and total light transmittance at a high level. It is more preferable that the refractive index of the light diffusing agent is lower than the refractive index of the aromatic polycarbonate resin.

The preferred average particle size of the light diffusing agent is 0.1 to 50 μm, more preferably 0.5 to 10 μm, and particularly preferably 1 to 5 μm. If the average particle size of the light diffusing agent is too small, sufficient light dispersion effect cannot be obtained, and if it is too large, the surface of the molded product may become rough or the mechanical strength of the molded product may decrease. Here, the average particle size of the light diffusing agent is the volume average particle size measured by the Coulter counter method. The Coulter counter method is a method in which an electrolyte containing suspended sample particles is passed through an aperture, and the change in the voltage pulse generated in proportion to the volume of the particles is read to quantify the particle size. The voltage pulse height is measured one by one to obtain a volume distribution histogram of the sample particles. Such particle size or particle size distribution measurement by the Coulter counter method is the most widely used particle size distribution measurement device.

From the viewpoint of light diffusion, the light diffusing agent (C) preferably has a refractive index difference (Δn) of 0.01 or more with respect to the polycarbonate resin (A). In order to fully exert light diffusion properties and suppress problems such as a light source behind the molded body (such as a light diffusion plate) being visible through the molded body, and furthermore to exert sufficient brightness, the light diffusing agent preferably has a refractive index difference of 0.05 or more with respect to the polycarbonate resin, and particularly preferably 0.07 or more.

The mass average particle diameter of the light diffusing agent (C) is usually 0.5 μm or more, preferably 1 μm or more, and more preferably 1.5 μm or more, and is usually 30 μm or less, preferably 20 μm or less, more preferably 10 μm or less, even more preferably 5 μm or less, and particularly preferably 3 μm or less. If the mass average particle diameter is too small, the light diffusing properties of the resulting polycarbonate resin composition will be poor, and when used as a diffusion plate or the like, the light source will tend to be visible through the composition or visibility will be poor. Conversely, if the mass average particle diameter is too large, the diffusing effect relative to the content may be low.

The light diffusing agent (C) may be used alone or in any combination and ratio of two or more kinds. It is preferable to use a silicone-based light diffusing agent in combination with another light diffusing agent.

The amount of light diffusing agent (C) is preferably 0.1 to 6.0 parts by weight, more preferably 1.0 to 5.0 parts by weight, per 100 parts by weight of linear aromatic polycarbonate resin (A). If it is less than 0.1 part by weight, the light is not scattered sufficiently, and the effect of preventing the visibility of the light source is inferior, and if it exceeds 6.0 parts by weight, the transmittance may decrease significantly.

The aromatic polycarbonate resin composition according to an embodiment of the present invention contains a phosphorus-based antioxidant (D). Since the aromatic polycarbonate resin composition simultaneously contains the fatty acid ester (B), the light diffusing agent (C), and the phosphorus-based antioxidant (D), it is possible to maintain and improve the excellent optical properties required for a light-diffusing molded product, and in particular to prevent deterioration of the initial optical properties of a molded product made of the resulting aromatic polycarbonate resin composition, and further to prevent deterioration due to usage conditions.

The phosphorus-based antioxidant (D) in the embodiment of the present invention is not particularly limited as long as it can provide the aromatic polycarbonate resin composition of the present invention, but it preferably contains a phosphite compound having the following phosphite structure:

In the aromatic polycarbonate resin composition according to an embodiment of the present invention, the phosphorus-based antioxidant (D) preferably contains at least one compound selected from a phosphite ester compound represented by the following formula (2), a phosphite ester compound represented by the following formula (3), a phosphite ester compound represented by the following formula (4), and a phosphite ester compound represented by the following formula (5).

The phosphorus-based antioxidant (D) preferably contains, for example, a compound represented by the following formula (2):

（式中、Ｒ^１は、炭素数１～２０のアルキル基を示し、ａは、０～３の整数を示す） Formula (2):

(wherein ^R1 represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 0 to 3).

In the formula (2), R ¹ is an alkyl group having 1 to 20 carbon atoms, and more preferably an alkyl group having 1 to 10 carbon atoms.

Examples of the compound represented by formula (2) include triphenyl phosphite, tricresyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, and trisnonylphenyl phosphite. Among these, tris(2,4-di-t-butylphenyl) phosphite is particularly suitable, and is commercially available, for example, as Irgafos 168 manufactured by BASF (Irgafos is a registered trademark of BASF Societas Europea).

The phosphorus-based antioxidant (D) preferably contains, for example, a compound represented by the following formula (3):

（式中、Ｒ^２、Ｒ^３、Ｒ^５及びＲ^６は、それぞれ独立して、水素原子、炭素数１～８のアルキル基、炭素数５～８のシクロアルキル基、炭素数６～１２のアルキルシクロアルキル基、炭素数７～１２のアラルキル基又はフェニル基を示す。Ｒ^４は、水素原子又は炭素数１～８のアルキル基を示す。Ｘは、単結合、硫黄原子又は式：－ＣＨＲ^７－（ここで、Ｒ^７は、水素原子、炭素数１～８のアルキル基又は炭素数５～８のシクロアルキル基を示す）で表される基を示す。Ａは、炭素数１～８のアルキレン基又は式：＊－ＣＯＲ^８－（ここで、Ｒ^８は、単結合又は炭素数１～８のアルキレン基を示し、＊は、酸素側の結合手であることを示す）で表される基を示す。Ｙ及びＺは、いずれか一方がヒドロキシル基、炭素数１～８のアルコキシ基又は炭素数７～１２のアラルキルオキシ基を示し、もう一方が水素原子又は炭素数１～８のアルキル基を示す。） Formula (3):

(In the formula, R ² , R ³ , R ⁵ and R ⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms, or a phenyl group. R ⁴ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. X represents a single bond, a sulfur atom, or a group represented by the formula: -CHR ⁷ - (wherein R ⁷ represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms). A represents an alkylene group having 1 to 8 carbon atoms or a group represented by the formula: *-COR ⁸ - (wherein R ⁸ represents a single bond or an alkylene group having 1 to 8 carbon atoms, and * represents a bond on the oxygen side. Either Y or Z represents a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms, or an aralkyloxy group having 7 to 12 carbon atoms, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms.

In formula (3), R ² , R ³ , R ⁵ and R ⁶ each independently represent a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms, an alkylcycloalkyl group having 6 to 12 carbon atoms, an aralkyl group having 7 to 12 carbon atoms or a phenyl group.

Here, examples of alkyl groups having 1 to 8 carbon atoms include methyl, ethyl, n-propyl, i-propyl, n-butyl, i-butyl, sec-butyl, t-butyl, t-pentyl, i-octyl, t-octyl, and 2-ethylhexyl groups. Examples of cycloalkyl groups having 5 to 8 carbon atoms include cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Examples of alkylcycloalkyl groups having 6 to 12 carbon atoms include 1-methylcyclopentyl, 1-methylcyclohexyl, and 1-methyl-4-i-propylcyclohexyl groups. Examples of aralkyl groups having 7 to 12 carbon atoms include benzyl, α-methylbenzyl, and α,α-dimethylbenzyl groups.

It is preferable that R ² , R ³ and R ⁵ are each independently an alkyl group having 1 to 8 carbon atoms, a cycloalkyl group having 5 to 8 carbon atoms or an alkylcycloalkyl group having 6 to 12 carbon atoms. In particular, it is preferable that R ² and R ⁵ are each independently a t-alkyl group such as a t-butyl group, a t-pentyl group or a t-octyl group, a cyclohexyl group or a 1-methylcyclohexyl group. In particular, it is preferable that R ³ is an alkyl group having 1 to 5 carbon atoms such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a t-butyl group or a t-pentyl group, and it is more preferable that R 3 is a methyl group, a t-butyl group or a t-pentyl group.

The ^R6 is preferably a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms, and more preferably a hydrogen atom, or an alkyl group having 1 to 5 carbon atoms, such as a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a sec-butyl group, a t-butyl group, or a t-pentyl group.

In formula (3), R ⁴ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms include the alkyl groups exemplified in the description of R ² , R ³ , R ⁵ , and R ^6. In particular, R ⁴ is preferably a hydrogen atom or an alkyl group having 1 to 5 carbon atoms, and more preferably a hydrogen atom or a methyl group.

In formula (3), X represents a single bond, a sulfur atom, or a group represented by the formula -CHR ⁷ -. Here, R ⁷ in the formula -CHR ⁷ - represents a hydrogen atom, an alkyl group having 1 to 8 carbon atoms, or a cycloalkyl group having 5 to 8 carbon atoms. Examples of the alkyl group having 1 to 8 carbon atoms and the cycloalkyl group having 5 to 8 carbon atoms include the alkyl groups and cycloalkyl groups exemplified in the explanation of R ² , R ³ , R ⁵ , and R ⁶ , respectively. In particular, X is preferably a single bond, a methylene group, or a methylene group substituted with a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, a t-butyl group, or the like, and more preferably a single bond.

In formula (3), A represents an alkylene group having 1 to 8 carbon atoms or a group represented by the formula *-COR ⁸ -. Examples of the alkylene group having 1 to 8 carbon atoms include a methylene group, an ethylene group, a propylene group, a butylene group, a pentamethylene group, a hexamethylene group, an octamethylene group, and a 2,2-dimethyl-1,3-propylene group, and the like, with a propylene group being preferred. Furthermore, R ⁸ in the formula *-COR ⁸ - represents a single bond or an alkylene group having 1 to 8 carbon atoms. Examples of the alkylene group having 1 to 8 carbon atoms represented by R ⁸ include the alkylene groups exemplified in the above description of A. R ⁸ is preferably a single bond or an ethylene group. Furthermore, * in the formula *-COR ⁸ - represents a bond on the oxygen side, and indicates that the carbonyl group is bonded to the oxygen atom of the phosphite group.

In formula (3), one of Y and Z represents a hydroxyl group, an alkoxy group having 1 to 8 carbon atoms, or an aralkyloxy group having 7 to 12 carbon atoms, and the other represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. Examples of the alkoxy group having 1 to 8 carbon atoms include a methoxy group, an ethoxy group, a propoxy group, a t-butoxy group, and a pentyloxy group. Examples of the aralkyloxy group having 7 to 12 carbon atoms include a benzyloxy group, an α-methylbenzyloxy group, and an α,α-dimethylbenzyloxy group. Examples of the alkyl group having 1 to 8 carbon atoms include the alkyl groups exemplified in the explanation of R ² , R ³ , R ⁵ , and R ⁶ above.

Examples of compounds represented by formula (3) include 2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosphepine, 6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propoxy]-2,4,8,10-tetra-t-butyldibenzo[d,f][1,3,2]dioxaphosphepine, 6 -[3-(3,5-di-t-butyl-4-hydroxyphenyl)propoxy]-4,8-di-t-butyl-2,10-dimethyl-12H-dibenzo[d,g][1,3,2]dioxaphosphocin, and 6-[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy]-4,8-di-t-butyl-2,10-dimethyl-12H-dibenzo[d,g][1,3,2]dioxaphosphocin. Among these, when the resulting aromatic polycarbonate resin composition is to be used in fields where optical properties are particularly required, 2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosphepine is suitable, and is commercially available, for example, as Sumilizer GP (Sumilizer is a registered trademark) manufactured by Sumitomo Chemical Co., Ltd.

The phosphorus-based antioxidant (D) preferably contains, for example, a compound represented by the following formula (4):

（式中、Ｒ^９及びＲ^１０は、それぞれ独立して、炭素数１～２０のアルキル基又はアルキル基で置換されていてもよいアリール基を示し、ｂ及びｃは、それぞれ独立して、０～３の整数を示す。） Formula (4):

(In the formula, R ⁹ and R ¹⁰ each independently represent an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group, and b and c each independently represent an integer of 0 to 3.)

Examples of the compound represented by formula (4) include bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite and phenyl bisphenol A pentaerythritol diphosphite. Bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite is commercially available under the trade name "ADEKA STAB PEP-24G" manufactured by ADEKA Corporation. Adeka STAB PEP-36 ("ADEKA STAB" is a registered trademark) manufactured by ADEKA Corporation is commercially available.

The phosphorus-based antioxidant (D) preferably contains, for example, a compound represented by the following formula (5):

Formula (5):

(In the formula, R ¹¹ to R ¹⁸ each independently represent an alkyl group or alkenyl group having 1 to 3 carbon atoms. R ¹¹ and R ¹² , R ¹³ and R ¹⁴ , R ¹⁵ and R ¹⁶ , and R ¹⁷ and R ¹⁸ may be bonded to each other to form a ring. R ¹⁹ to R ²² each independently represent a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. d to g each independently represent an integer of 0 to 5. X ¹ to X ⁴ each independently represent a single bond or a carbon atom. When X ¹ to X ⁴ are single bonds, among R ¹¹ to R ²² , the functional group linked to the single bond is excluded from general formula (5).)

A specific example of the compound represented by formula (5) is bis(2,4-dicumylphenyl)pentaerythritol diphosphite, which is commercially available under the trade name "Doverphos (registered trademark) S-9228" manufactured by Dover Chemical Co., and under the trade name "ADEKA STAB PEP-45" (bis(2,4-dicumylphenyl)pentaerythritol diphosphite) manufactured by ADEKA Corporation.

The above-mentioned aromatic polycarbonate resin composition preferably satisfies at least one selected from the following:
The phosphite compound represented by the formula (2) contains tris(2,4-di-t-butylphenyl)phosphite;
The phosphite compound represented by the formula (3) contains 2,4,8,10-tetra-t-butyl-6-[3-(3-methyl-4-hydroxy-5-t-butylphenyl)propoxy]dibenzo[d,f][1,3,2]dioxaphosphepine;
The phosphite compound represented by the formula (4) contains 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane; and The phosphite compound represented by the formula (5) contains bis(2,4-dicumylphenyl)pentaerythritol diphosphite.

It is preferable that the phosphorus-based antioxidant (D) contains at least two compounds, one of which is a compound represented by general formula (2). In this case, the amount of the compound represented by general formula (2) is preferably 20 to 90% by mass, more preferably 30 to 80% by mass, and particularly preferably 40 to 70% by mass, of the total amount of the phosphorus-based antioxidant (D).

The amount of phosphorus-based antioxidant (D) is 0.005 to 0.5 parts by weight, preferably 0.04 to 0.1 parts by weight, and more preferably 0.04 to 0.08 parts by weight, per 100 parts by weight of aromatic polycarbonate resin (A). If the amount of phosphorus-based antioxidant (D) is less than 0.005 parts by weight, the effect of improving light transmittance or hue is insufficient. Conversely, if the amount of phosphorus-based antioxidant (D) exceeds 0.5 parts by weight, the effect of improving light transmittance or hue is also insufficient.

The aromatic polycarbonate resin composition of the present invention preferably contains, together with the fatty acid ester (B), a light diffusing agent (C), a phosphorus-based antioxidant (D), and an aromatic compound (E) represented by the following formula (1). In this way, by using the fatty acid ester (B), the light diffusing agent (C), the phosphorus-based antioxidant (D), and the aromatic compound (E), it is possible to prevent deterioration of the molded article made of the obtained aromatic polycarbonate resin composition, such as deterioration due to aging, in addition to deterioration caused by the usage conditions, while maintaining the excellent optical properties required of the light diffusing molded article.

For example, thermal degradation (clouding or coloring) of optical molded products molded from aromatic polycarbonate resin compositions caused by long-term light irradiation from a light source (such as an LED light source) is effectively prevented. When a light-diffusing molded product is exposed to harsh conditions such as under the hot sun and/or light irradiation for a long period of time, the temperature of the surface of the molded product may increase, and thermal degradation of the linear aromatic polycarbonate resin (A) contained in the aromatic polycarbonate resin composition may progress little by little. Furthermore, the fatty acid ester (B) in the resin composition may be modified, impairing the transparency (brightness or light transmittance) expected of aromatic polycarbonate resin compositions used in ordinary light-diffusing molded products, and clouding or coloring (light to dark coloring) may occur on the surface of the molded product.

In view of this problem, the present inventors conducted intensive research and found that a specific aromatic compound (E) represented by the following formula (1) is particularly effective as a compound for inhibiting deterioration such as modification of the fatty acid ester (B), and that by adding the specific aromatic compound (E) to the fatty acid ester (B) in advance or before melt-kneading to obtain an aromatic polycarbonate resin composition, deterioration of the fatty acid ester (B) in a molded article can be inhibited and the phenomenon of clouding or coloring (light to dark coloring) can be reduced or alleviated.
Formula (1):

The amount of aromatic compound (E) used in the embodiment of the present invention is preferably less than 0.003 parts by weight per 100 parts by weight of aromatic polycarbonate resin (A). In order to obtain the effect of suppressing the modification of fatty acid ester (B) by aromatic compound (E), the amount of aromatic compound (E) is set to 0.0001 parts by weight or more per 100 parts by weight of aromatic polycarbonate resin (A). The amount of aromatic compound (E) is more preferably 0.0005 parts by weight or more and 0.003 parts by weight or less per 100 parts by weight of aromatic polycarbonate resin (A). If the amount of aromatic compound (E) is less than 0.0001 parts by weight, the effect of suppressing cloudiness or coloring is insufficient. Conversely, if the amount of aromatic compound (E) exceeds 0.003 parts by weight, it is not desirable because it may not be possible to achieve the high level of light transmittance and hue required for the optical molded body.

In the present invention, the aromatic polycarbonate resin composition according to the embodiment can be appropriately used with, for example, an ultraviolet absorber, which is a component that further improves the weather resistance of the resulting aromatic polycarbonate resin composition, depending on the application of the molded product obtained by molding the aromatic polycarbonate resin composition.

As the ultraviolet absorbing agent, for example, ultraviolet absorbing agents that are usually blended with polycarbonate resins, such as benzotriazole-based compounds, triazine-based compounds, benzophenone-based compounds, and anilide oxalate-based compounds, can be used alone or in combination of two or more kinds.

Benzotriazole compounds include, for example, 2-(2-hydroxy-5-t-octylphenyl)benzotriazole, 2-(3-tert-butyl-2-hydroxy-5-methylphenyl)-5-chloro-2H-benzotriazole, 2-(3,5-di-tert-pentyl-2-hydroxyphenyl)-2H-benzotriazole, and 2-(2H-benzotriazole-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalimide. 2-(2-hydroxy-4-octyloxyphenyl)-2H-benzotriazole, 2-(2-hydroxy-5-tert-octylphenyl)-2H-benzotriazole, 2-[2'-hydroxy-3,5-di(1,1-dimethylbenzyl)phenyl]-2H-benzotriazole, 2,2'-methylenbis[6-(2H-benzotriazol-2-yl)4-(1,1,3,3-tetramethylbutyl)phenol] and the like. Among these, 2-(2-hydroxy-5-t-octylphenyl)benzotriazole is particularly suitable, and commercially available examples include TINUVIN 329 (TINUVIN is a registered trademark) manufactured by BASF, Seesorb 709 manufactured by Shipro Kasei Co., Ltd., and Chemisorb 79 manufactured by Chemipro Kasei Co., Ltd.

Examples of triazine compounds include 2,4-diphenyl-6-(2-hydroxyphenyl-4-hexyloxyphenyl)-1,3,5-triazine, 2-[4,6-bis(2,4-dimethylphenyl)-1,3,5-triazin-2-yl]-5-(octyloxy)phenol, and 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]phenol. For example, TINUVIN 1577 manufactured by BASF is commercially available.

Examples of commercially available oxalic acid anilide compounds include Sanduvor VSU manufactured by Clariant Japan Co., Ltd.

Examples of benzophenone compounds include 2,4-dihydroxybenzophenone and 2-hydroxy-4-n-octoxybenzophenone.

The amount of the ultraviolet absorber is 0 to 1.0 part by weight, preferably 0 to 0.5 parts by weight, per 100 parts by weight of the aromatic polycarbonate resin (A). If the amount of the ultraviolet absorber exceeds 1.0 part by weight, the initial hue of the resulting aromatic polycarbonate resin composition may be deteriorated. Furthermore, if the amount of the ultraviolet absorber is 0.1 part by weight or more, the effect of further improving the weather resistance of the aromatic polycarbonate resin composition is particularly significant.

The aromatic polycarbonate resin composition according to an embodiment of the present invention may contain an epoxy compound. In this way, when the aromatic polycarbonate resin composition simultaneously contains the fatty acid ester (B), the aromatic compound (E), and the epoxy compound, it is possible to maintain and improve the excellent optical properties required for a light-diffusing molded article, while preventing deterioration due to usage conditions, aging, and other deterioration without deteriorating the initial optical properties of the molded article made of the resulting aromatic polycarbonate resin composition.

The epoxy compound is not particularly limited as long as it has at least one epoxy group in the molecule and can obtain the aromatic polycarbonate resin composition of the present invention. The epoxy compound (F) can include, for example, 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, epoxidized soybean oil, ε-caprolactone-modified 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, epoxy group-containing acrylic-styrene polymer, 2,2-bis(4-hydroxycyclohexyl)propane-diglycidyl ether, and the like. The epoxy compound (F) preferably includes 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate.

The aromatic polycarbonate resin composition of the present invention preferably contains 0.001 to 0.2 parts by weight, more preferably 0.002 to 0.1 parts by weight, and particularly preferably 0.005 to 0.05 parts by weight of an epoxy compound per 100 parts by weight of a linear aromatic polycarbonate resin. When the aromatic polycarbonate resin composition of the present invention contains 0.001 to 0.2 parts by weight of an epoxy compound per 100 parts by weight of a linear aromatic polycarbonate resin, the aromatic polycarbonate resin composition of the present invention can improve the initial optical properties (integral transmittance and yellowness index) of a molded product made of the resulting aromatic polycarbonate resin composition while maintaining and improving the excellent optical properties required for a light-diffusing molded product, and can prevent deterioration due to usage conditions and aging.

Furthermore, the aromatic polycarbonate resin composition according to the embodiment may contain various additives such as heat stabilizers, other antioxidants, colorants, release agents, softeners, antistatic agents, and impact modifiers, as well as polymers other than linear aromatic polycarbonate resins, as appropriate, within the scope of not impairing the effects of the present invention.

The aromatic polycarbonate resin composition of the embodiment of the present invention can be produced by mixing a linear aromatic polycarbonate resin, a fatty acid ester (B), a light diffusing agent (C), and a phosphorus-based antioxidant (D), and, if necessary, mixing an aromatic compound (E), an epoxy compound, the various additives, and a polymer other than the linear aromatic polycarbonate resin. As long as the aromatic polycarbonate resin composition of the present invention can be obtained, the production method is not particularly limited, and the type and amount of each component can be appropriately adjusted. The method of mixing the components is also not particularly limited, and examples include a method of mixing using a known mixer such as a tumbler or ribbon blender, and a method of melt kneading using an extruder. By these methods, pellets of the aromatic polycarbonate resin composition can be easily obtained. The aromatic compound (E) may be mixed before melt kneading, or may be added or mixed in advance to the fatty acid ester (B).

There are no particular limitations on the shape and size of the pellets of the aromatic polycarbonate resin composition obtained as described above, and they may be of the same shape and size as general resin pellets. For example, the shape of the pellets may be an elliptical cylinder, a cylindrical shape, etc. The pellet size is preferably about 2 to 8 mm in length, and in the case of an elliptical cylinder, the major axis of the cross-sectional ellipse is preferably about 2 to 8 mm, and the minor axis is preferably about 1 to 4 mm, and in the case of a cylindrical shape, the diameter of the cross-sectional circle is preferably about 1 to 6 mm. Each of the obtained pellets may be of this size, or all of the pellets forming the pellet aggregate may be of this size, or the average value of the pellet aggregate may be of this size, and there are no particular limitations.

The light-diffusing molded article according to the embodiment of the present invention can be obtained by molding the aromatic polycarbonate resin composition. As a large, thin light diffusion plate (particularly a light diffusion plate for an image display device), a light diffusion plate having a surface area of 500 to 50,000 ^cm2 can be obtained. The surface area of the light diffusion plate is preferably 1,000 to 25,000 ^cm2 , and the thickness is preferably 0.3 to 3 mm. Thus, according to the aromatic polycarbonate resin composition of the present invention, a large, dimensionally stable, and thin (lightweight) light diffusion plate can be produced.

As long as the light-diffusing molded article of the present invention can be obtained, the method for producing the light-diffusing molded article is not particularly limited. For example, a method for molding an aromatic polycarbonate resin composition by a known injection molding method, compression molding method, etc. can be used.

The light-diffusing molded article according to the present invention can be used, for example, as a light diffusion plate, a light diffusion film, parts for electronic and electrical equipment, office equipment, vehicle parts, machine parts, agricultural materials, fishing materials, transport containers, packaging containers, miscellaneous goods, etc. Specifically, it is suitable as a light diffusion plate for an image display device (light diffusion plate used in the backlight module of a liquid crystal display device, etc., light diffusion plate used in the screen of a projection type display device such as a projector television, etc.). Various light sources (cold cathode fluorescent tubes, LEDs, etc.) can be used as the backlight module of a liquid crystal display device, etc.

As described above, the embodiments have been described as examples of the present invention. However, the technology of the present invention is not limited to these, and can be applied to embodiments in which modifications, substitutions, additions, omissions, etc. are made as appropriate.

The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. Unless otherwise specified, "parts" and "%" are based on weight.

The following raw materials were used:
1. Linear aromatic polycarbonate resin (A):
Polycarbonate resin (PC) synthesized from bisphenol A and carbonyl chloride
Viscosity average molecular weight: 15,000, SD Polyca 200-80 (product name) manufactured by Sumika Polycarbonate Co., Ltd., "SD Polyca" is a registered trademark of Sumika Polycarbonate Co., Ltd.

2. Fatty acid ester (B):
Glycerin monostearate (GMS), manufactured by Riken Vitamin Co., Ltd., product name Rikemal S-100A

3. Light diffusing agent (C):
3-1. Polymethylsilsesquioxane-based diffusing agent Tospearl 120S (product name) manufactured by Momentive Corporation, hereinafter also referred to as (C1).
3-2. Acrylic diffusing agent GM-0449S (product name) manufactured by Ganz Chemical Industry Co., Ltd., hereinafter also referred to as (C2).
3-3. Styrene-methyl methacrylate copolymer crosslinked fine particles SMX-12R (product name) manufactured by Sekisui Chemical Co., Ltd., hereinafter also referred to as (C3).

ＢＡＳＦ社製のイルガフォス１６８（商品名）、以下（Ｄ１）ともいう。 4. Phosphorus-based antioxidant (D):
4-1. Tris(2,4-di-t-butylphenyl)phosphite represented by the following formula:

Irgafos 168 (product name) manufactured by BASF, hereinafter also referred to as (D1).

ＡＤＥＫＡ製のアデカスタブＰＥＰ－３６（商品名）、以下（Ｄ２）ともいう。
５．芳香族化合物（Ｅ）： 4-2. Bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite (IUPAC name: 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane) represented by the following formula:

Adeka STAB PEP-36 (product name) manufactured by ADEKA, hereinafter also referred to as (D2).
5. Aromatic compounds (E):

3,5-di-t-butyl-4-hydroxytoluene (BHT)
Manufactured by Wako Pure Chemical Industries, Ltd.; hereinafter also referred to as (E).

6. Epoxy compound (F):
3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate CELLOXIDE 2021P (product name) manufactured by Daicel Chemical Industries, Ltd.

(Examples 1 to 9 and Comparative Examples 1 to 3)
The raw materials were all charged into a tumbler in the proportions shown in Table 1 and dry-mixed for 10 minutes, and then melt-kneaded at a melting temperature of 230° C. using a twin-screw extruder (TEX30α, manufactured by The Japan Steel Works, Ltd.) to obtain pellets of the aromatic polycarbonate resin composition of each of Examples 1 to 11 and Comparative Examples 1 and 2. The pellets obtained in the Examples and Comparative Examples were all approximately elliptical cylindrical, and an aggregate consisting of 100 pellets had an average length of about 5.1 mm to about 5.4 mm, an average major axis of the elliptical cross section of about 4.1 mm to about 4.3 mm, and an average minor axis of about 2.2 mm to about 2.3 mm.

Using the obtained pellets, evaluation test pieces were prepared according to the following method and subjected to evaluation. The results are shown in Tables 1 and 2.

(Method of preparing test pieces)
The pellets thus obtained were dried at 120° C. for 4 hours or more, and then, using an injection molding machine (FANUC LTD., ROBOSHOT S2000i100A), a molding temperature of 290° C. and a mold temperature of 80° C. were used to prepare three-stage plate-shaped test pieces with a width of 50 mm and a length of 90 mm (3 mm thick part: length 35 mm/2 mm thick part: length 30 mm/1 mm thick part: length 25 mm).

(Test Piece Evaluation Method)
1. Total light transmittance (%):
The total light transmittance was measured using a 1 mm portion of the obtained three-stage plate-shaped test piece in accordance with JIS K7361. The larger the value, the better the light transmittance of the molded article. A total light transmittance value of 40% or more for a molded article with a thickness of 1 mm was considered to be good.

2. Light diffusion degree (degrees):
The light diffusion (D50) was determined using an automatic variable angle photometer (Goniophotometer GP-1R manufactured by Murakami Color Research Laboratory) using a 1 mm portion of the three-stage plate-shaped test piece used in 1 above. The detailed measurement method is as follows. The larger this value, the better the light diffusion of the molded product. A straight light beam from the light source of the automatic variable angle photometer was applied to the test piece from the normal direction, the intensity of the transmitted light was measured with a movable light receiver, the transmittance was plotted against the angle from the normal direction, and the angle (D50) at which the transmittance was 50% of the straight light transmittance was determined. The unit is "degrees", and light diffusion (D50) of 30 degrees or more was considered to be good.

3. Prevention of light source from being seen through (visual judgment):
A rectangular hole measuring 3 cm x 5 cm was drilled in the center of a Philips 20W straight tube LED lamp, and an injection molded plate measuring 3 cm x 5 cm x 1 mm was placed in that area at a height of about 1.5 cm from the LED light source. The light source visibility prevention was visually judged from a height of about 20 cm above the injection molding plate installed on the LED lamp. If the light diffusion is sufficient and the outline of the LED light source disappears, it is rated as very good. The case where the outline of the LED light source was somewhat visible was judged as good (◯), and the case where the light diffusion was poor and the outline of the LED light source was clearly visible was judged as poor (×).

4. Yellowness:
Using a 1 mm section of the obtained three-stage plate-shaped test piece, a spectrophotometer (Hitachi, Ltd., UH4150) was used to measure the heat resistance of each test piece using a standard light source D65 and a 10-degree visual field. The yellowness index (hereinafter, YI) was determined. The heating test was carried out by placing the test piece in an inert oven IPHH-201M manufactured by Espec Corporation and holding it at 90°C for 500 hours. A value of 3.5 or less is good (indicated by ◎ in the table), a value between 3.5 and 4.0 is acceptable (indicated by ○ in the table), and a value above 4.0 is poor (indicated by × in the table). (shown below).

Table 1 shows the raw materials and mixing ratios for each example and comparative example, as well as the evaluation results.

The aromatic polycarbonate resin compositions of Examples 1 to 9 contain a linear aromatic polycarbonate resin, a fatty acid ester (B), a light diffusing agent (C), and a phosphorus-based antioxidant (D), and optionally contain an aromatic compound (E), an epoxy compound, etc., each in a specific ratio. Therefore, the test pieces molded from the aromatic polycarbonate resin compositions have the required high total light transmittance, light diffusing property, and light source visibility prevention property, have low yellowness, and show almost no deterioration after heating tests.

Furthermore, molded articles made from such aromatic polycarbonate resin compositions have low yellowness and excellent hue, and also show almost no deterioration after heating tests.

In contrast, the aromatic polycarbonate resin composition of Comparative Example 1 contained a small amount of light diffusing agent, so the degree of light diffusion was low and the prevention of light source visibility was poor. Furthermore, the aromatic polycarbonate resin composition of Comparative Example 2 contained a large amount of light diffusing agent, so the total light transmittance was low and the yellowness index was high before and after the heating test. The aromatic polycarbonate resin composition of Comparative Example 3 contained a large amount of phosphorus-based antioxidant, so the yellowness index was high after the heating test.

The above describes the embodiment as an example of the technology of the present invention. For this purpose, a detailed description has been provided.

Therefore, the components described in the detailed description may include not only components essential for solving the problem, but also components that are not essential for solving the problem in order to illustrate the above technology. Therefore, the fact that these non-essential components are described in the detailed description should not immediately lead to the determination that these non-essential components are essential.

The above-described embodiment is intended to illustrate the technology of the present invention, and various modifications, substitutions, additions, omissions, etc. may be made within the scope of the claims or their equivalents.

The polycarbonate resin composition of the present invention does not impair the inherent properties of polycarbonate resin, such as heat resistance and mechanical strength, and has excellent thermal stability, high transparency, light transmittance, and light diffusion properties. Moreover, even if the molded product obtained is exposed for a long period of time under hot weather and/or high temperature conditions due to light source irradiation, the transparency and transmittance are not likely to decrease (they are not likely to become cloudy or colored). Therefore, even if the molded product is a thin molded product (diffusion plate) with a thickness of, for example, about 0.3 mm, the hue is not likely to change and the appearance is not likely to deteriorate (deteriorate), and even if the product is exposed for a long period of time under high temperature conditions due to the external environment or light source, the transparency is not likely to decrease (they are not likely to become cloudy or colored). In other words, a polycarbonate resin composition with high light diffusion properties that does not reduce light transmittance and yet does not allow the light source to be seen through can be provided, and its industrial value is extremely high.

Claims (13)

An aromatic polycarbonate resin composition comprising a linear aromatic polycarbonate resin (A), a fatty acid ester (B), a light diffusing agent (C), a phosphorus-based antioxidant (D), and an aromatic compound (E) represented by the following formula (1):
The aromatic polycarbonate resin composition contains, relative to 100 parts by weight of the linear aromatic polycarbonate resin (A), 0.01 to 0.5 parts by weight of a fatty acid ester (B), 0.1 to 6 parts by weight of a light diffusing agent (C), 0.005 to 0.5 parts by weight of a phosphorus-based antioxidant (D), and up to 0.003 parts by weight of an aromatic compound (E).
Formula (1):

The aromatic polycarbonate resin composition according to claim 1, wherein the fatty acid ester (B) comprises a condensation compound of an aliphatic carboxylic acid and an alcohol. The aromatic polycarbonate resin composition according to claim 2, wherein the fatty acid ester (B) includes esters of aliphatic monocarboxylic acids and aliphatic dicarboxylic acids having 6 to 36 carbon atoms and aliphatic saturated monohydric alcohols and aliphatic saturated polyhydric alcohols having 30 or less carbon atoms. The aromatic polycarbonate resin composition according to claim 3, wherein the fatty acid ester (B) is glycerin monostearate. The aromatic polycarbonate resin composition according to claim 1, wherein the light diffusing agent (C) is a silicone-based light diffusing agent, an acrylic-based light diffusing agent, or a combination thereof. 2. The aromatic polycarbonate resin composition according to claim 1, wherein the phosphorus-based antioxidant (D) contains a phosphite compound having the following phosphite structure:
7. The aromatic polycarbonate resin composition according to claim 6, wherein the phosphorus-based antioxidant (D) contains at least one compound selected from the group consisting of phosphite compounds represented by the following formulas (2) and (3):
Formula (2):

[In the formula, R ¹ represents an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group, and a represents an integer of 0 to 3.]
Formula (4):

[In the formula, R ⁹ and R ¹⁰ each represent an alkyl group having 1 to 20 carbon atoms or an aryl group which may be substituted with an alkyl group, and b and c each represent an integer of 0 to 3.] The aromatic polycarbonate resin composition according to claim 7, which satisfies at least one selected from the following:
The phosphite compound represented by the formula (2) contains tris(2,4-di-t-butylphenyl)phosphite; and the phosphite compound represented by the formula (4) contains 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5,5]undecane. The aromatic polycarbonate resin composition according to claim 8, wherein the phosphorus-based antioxidant (D) contains at least a compound represented by formula (2), and the amount of the compound represented by formula (2) is 20 to 100 mass% of the total amount of the phosphorus-based antioxidant (D). The aromatic polycarbonate resin composition according to claim 8, wherein the phosphorus-based antioxidant (D) contains at least two compounds, one of which is a compound represented by formula (2), and the amount of the compound represented by formula (2) is 20 to 90 mass% of the total amount of the phosphorus-based antioxidant (D). The aromatic polycarbonate resin composition according to claim 1, further comprising at least one selected from the group consisting of a heat stabilizer, a colorant, a release agent, a softener, an antistatic agent, and an impact modifier. A light-diffusing molded article comprising the aromatic polycarbonate resin composition according to any one of claims 1 to 11. The light-diffusing molded article according to claim 9, wherein the light-diffusing molded article is a light-diffusing plate or film for an image display device.