Aromatic polycarbonate resin composition and light diffusing molded article

Abstract

To provide an aromatic polycarbonate resin composition which is excellent in heat stability, has high transparency, light transmittance and light diffusion property, and causes little lowering of transparency and light permeability, without impairing characteristics such as original heat resistance and mechanical strength of a polycarbonate resin.SOLUTION: An aromatic polycarbonate resin composition contains a straight-chain 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 pts.wt. of the fatty acid ester (B), 0.1 to 10 pts.wt. of the light diffusing agent (C), 0.005 to 0.5 pts.wt. of the phosphorus-based antioxidant (D), and less than 0.003 pts.wt. of the aromatic compound (E) with respect to 100 pts.wt. of the straight-chain aromatic polycarbonate resin (A).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an aromatic polycarbonate resin composition and a light-diffusing molded article. [Background technology]

[0002] Polycarbonate resins are excellent in impact resistance, heat resistance, transparency, etc., and therefore have been conventionally 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 superior heat resistance and dimensional stability compared to light-diffusing molded products made of acrylic resins, and therefore are used in a wide range of fields, such as electric light covers, meters, signboards (especially internally illuminated), resin 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-type 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.).

[0003] In recent years, with the trend of image display devices becoming larger, thinner (lighter), more complex in shape, and with higher performance, there has been an increasing demand for light diffusing molded products, particularly light diffusion plates and light diffusing films used in image display devices, to become larger, thinner (lighter), more complex in shape, and with higher performance, and there is a demand for aromatic polycarbonate-based resin compositions having excellent fluidity during molding.

[0004] Patent Document 1 describes that a pentaerythritol-based ester compound is added to an aromatic polycarbonate-based resin to reduce its molecular weight through transesterification, thereby improving the fluidity. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2013 / 011977 Summary of the Invention [Problem to be solved by the invention]

[0006] However, the polycarbonate resin composition disclosed in Patent Document 1 does not fully satisfy recent demands for materials, such as little decrease in transparency and light transmittance even when molded at high temperatures to produce thin-walled products, and the ability to produce large-sized products.

[0007] Furthermore, in recent years, there has been a demand for light-diffusing molded articles (e.g., light diffusion plates for image display devices) used in molded, thin, in-vehicle 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, and yet do not allow the light source to be seen through them.

[0008] The present invention aims 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 unlikely to deteriorate in transparency and light transmittance (is unlikely to become cloudy or colored) even when a large, thin molded product having a thickness 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, it does not deteriorate in light transmittance even when it is large, and yet has high light diffusion properties that prevent the light source from being seen through it. [Means for solving the problem]

[0009] The present inventors have conducted extensive research to solve the above problems, and as a result have found that an aromatic polycarbonate resin composition comprising a linear aromatic polycarbonate resin, a fatty acid ester (B), a light diffusing agent (C), a phosphorus-based antioxidant (D), and, as 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 with a light source for a long period of time, the transparency and transmittance are less likely to decrease (opacity or coloring is less likely to occur), i.e., a polycarbonate with high light diffusivity that does not decrease light transmittance and yet does not allow a light source to be seen through can be obtained, thereby completing the present invention.

[0010] 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): [ka] Effect of the Invention

[0011] The polycarbonate resin composition of the present invention does not lose the inherent properties of polycarbonate resin such as heat resistance and mechanical strength, has excellent thermal stability, and is high in transparency, light transmittance, and light diffusion. Moreover, even if the obtained molded article is exposed for a long period of time under high temperature conditions due to a hot sun environment and / or light source irradiation, the transparency and transmittance are not likely to decrease (there is little clouding or coloring). Therefore, even if the molded article (diffusion plate) has a thickness of about 0.3 mm, the hue is not likely to change and the appearance is not likely to deteriorate (deteriorate), and even if the molded article 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 (there is little clouding or coloring), that is, a polycarbonate resin composition having 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 the industrial value of the composition is extremely high. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] Hereinafter, the embodiments will be described in detail. However, more detailed explanation than necessary may be omitted. For example, detailed explanation of already well-known matters or duplicate explanation of substantially the same configuration may be omitted. This is to avoid the following explanation becoming unnecessarily redundant and to facilitate understanding by those skilled in the art.

[0013] The inventors provide the following description so that those skilled in the art can fully understand the present invention, and do not intend to limit the subject matter described in the claims.

[0014] 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, as necessary, a specific aromatic compound (E).

[0015] 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, but branched aromatic polycarbonates are excluded from the scope of the present invention as much as possible because they reduce transparency and light transmittance. Examples of linear aromatic polycarbonate resins include polymers obtained by the phosgene method in which various dihydroxydiaryl compounds are reacted with phosgene, or the ester exchange method in which a dihydroxydiaryl compound is reacted with a carbonate ester such as diphenyl carbonate. A representative example includes a polycarbonate resin produced from 2,2-bis(4-hydroxyphenyl)propane (bisphenol A).

[0016] Examples of the dihydroxydiaryl compound include, in addition to bisphenol A, 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, 4,4'-dihydroxydiphenyl ether, 4,4'-dihydroxy-3,3'-dimethyldiphenyl ether, and other dihydroxydiaryl ethers; dihydroxydiaryl sulfides such as 4,4'-dihydroxydiphenyl sulfide, 4,4'-dihydroxydiphenyl sulfoxide, 4,4'-dihydroxy-3,3'-dimethyldiphenyl sulfoxide, and other dihydroxydiaryl sulfones such as 4,4'-dihydroxydiphenyl sulfone, 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, and other compounds can be used in combination.

[0017] 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. may be used as necessary.

[0018] 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 obtained polycarbonate resin composition without impairing the inherent properties such as heat resistance, mechanical strength, etc. Moreover, even when a molded thin molded product (light guide plate) having a thickness of about 0.3 mm is exposed for a long period of time under high temperature conditions such as irradiation by a light source, the decrease in transparency (opacity or coloration is unlikely to occur) can be reduced.

[0019] For example, thermal deterioration (clouding or coloring) of an optical molded article molded from an aromatic polycarbonate resin composition caused by long-term light irradiation from a light source (such as an LED light source) is effectively prevented. When an optical molded article 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 article may increase, and thermal deterioration 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 an aromatic polycarbonate resin composition used in a normal optical molded article, and clouding or coloring (light to dark coloring) may occur on the surface of the molded article.

[0020] In view of this problem, the present inventors have conducted intensive research and found that a specific aromatic compound (E) is particularly effective as a compound for inhibiting deterioration such as modification of the fatty acid ester (B) and discoloration resulting therefrom, and that by adding the specific aromatic compound (E) before melt-kneading an aromatic polycarbonate resin composition, deterioration of the fatty acid ester (B) in a molded product can be inhibited and the phenomenon of clouding or discoloration (light to dark coloring) can be reduced or alleviated.

[0021] 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.

[0022] The aliphatic carboxylic acid includes saturated or unsaturated monocarboxylic acid, dicarboxylic acid, tricarboxylic acid, etc. The aliphatic carboxylic acid also includes alicyclic carboxylic acid. Among these, monocarboxylic acid and dicarboxylic acid having 6 to 36 carbon atoms are preferable, and saturated monocarboxylic acid having 6 to 36 carbon atoms is more preferable.

[0023] Specific examples of the aliphatic carboxylic acid 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.

[0024] The alcohol includes 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, an aryl group, etc. 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. The aliphatic alcohols also include alicyclic alcohols.

[0025] 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.

[0026] Specific examples of the fatty acid ester (B) include 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, and the like, 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 for example, commercially available products 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 Pharmaceuticals).

[0027] 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, based on 100 parts by weight of the polycarbonate resin (A). When the amount of the 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.

[0028] In the 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 limit in terms of 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 difficult to be compatible with it and exists as particles.

[0029] 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. Among 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, ultrathin glass flakes (manufactured by the sol-gel method), irregular glass, etc. Similarly, various shapes can be adopted for other inorganic fine particles.

[0030] As the polymer fine particles, those that are spherical in terms of light diffusion are preferred, and the closer to a perfect sphere, the more preferred. 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 the silicone-based light diffusing agent, "Tospearl (registered trademark) 120S" manufactured by Momentive Performance Materials Japan Co., Ltd. can be used, and as the 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 Co., Ltd. can be used.

[0031] 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. The light diffusing agent can be obtained by using a general emulsion polymerization method, solution polymerization method, dispersion polymerization method, suspension polymerization method, bulk polymerization method, soap-free polymerization method, seed polymerization method, etc. Among these polymerization methods, emulsion polymerization method, dispersion polymerization method, and suspension polymerization method are preferred, and from the viewpoint of the physical properties of the light diffusing plate, emulsion polymerization method and dispersion polymerization method are particularly preferred.

[0032] The crosslinking agent used in the styrene-methyl methacrylate copolymer crosslinked microparticles may be any radically polymerizable monomer that contains 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.

[0033] The average particle size of the styrene-methyl methacrylate copolymer crosslinked fine particles is 5 to 30 μm. More preferably, the 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 obtained light diffusion plate maintains smoothness, so that light scattering is insufficient and light diffusion is poor. If the average particle size is more than 30 μm, the surface state of the obtained light diffusion plate approaches smoothness, so that light travels straight through and transmits, resulting in reduced light scattering and poor light diffusion and light source transmission prevention, which is not preferable. Common methods for measuring the average particle size of fine particles include the Coulter method, dynamic light scattering method, and centrifugal sedimentation method.

[0034] The refractive index of the styrene-methyl methacrylate copolymer crosslinked fine particles is in the range of 1.54 to 1.57. More preferably, it is in the range of 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 diffusibility may decrease. The refractive index can be changed by adjusting the polymerization ratio of each of the styrene and methyl methacrylate monomers when copolymerizing the fine particles.

[0035] Commercially available styrene-methyl methacrylate copolymer crosslinked fine particles include, for example, 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.

[0036] A typical method for measuring the refractive index of styrene-methyl methacrylate copolymer crosslinked fine particles is the Becke method. Resin particles are placed on a slide glass, and a refractive index liquid (CARGILLE's standard refractive index liquid) is dropped onto the resin particles. The resin particles and the refractive index liquid are mixed well, and a sodium lamp is irradiated from below to observe the particle outline from above. If the outline is not visible, the refractive index of the refractive index liquid is deemed to be equal to that of the resin particles. 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 that of the aromatic polycarbonate resin.

[0037] 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 article may become rough, or the mechanical strength of the molded article 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 particle size is quantified by reading the change in the voltage pulse generated in proportion to the volume of the particles, and 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 method for particle size distribution measurement.

[0038] 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, suppress defects such as a light source behind the molded product (such as a light diffusion plate) being visible through the molded product, and furthermore, to exert sufficient brightness, the light diffusing agent more preferably has a refractive index difference of 0.05 or more with respect to the polycarbonate resin, particularly preferably 0.07 or more.

[0039] 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 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 property of the resulting polycarbonate resin composition is poor, and when used as a diffusion plate or the like, the light source tends to be visible through the composition or the visibility is poor. Conversely, if the mass average particle diameter is too large, the diffusing effect relative to the content may be low.

[0040] 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.

[0041] The amount of the light diffusing agent (C) is preferably 0.1 to 6.0 parts by weight, more preferably 1.0 to 5.0 parts by weight, based on 100 parts by weight of the linear aromatic polycarbonate resin (A). If the amount is less than 0.1 part by weight, the light is not sufficiently scattered, and the effect of preventing the visibility of the light source is poor, while if the amount exceeds 6.0 parts by weight, the transmittance may be significantly reduced.

[0042] 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 article, and in particular to prevent the initial optical properties of a molded article made of the obtained aromatic polycarbonate resin composition from being deteriorated, and further to prevent deterioration due to the usage conditions.

[0043] 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: [ka]

[0044] 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 the group consisting of a phosphite compound represented by the following formula (2), a phosphite compound represented by the following formula (3), a phosphite compound represented by the following formula (4), and a phosphite compound represented by the following formula (5).

[0045] The phosphorus-based antioxidant (D) preferably contains, for example, a compound represented by the following formula (2).

[0046] Formula (2): [ka] (In the formula, R 1 represents an alkyl group having 1 to 20 carbon atoms, and a represents an integer of 0 to 3.

[0047] 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.

[0048] Examples of the compound represented by formula (2) include triphenyl phosphite, tricresyl phosphite, tris(2,4-di-t-butylphenyl) phosphite, trisnonylphenyl phosphite, etc. Among these, tris(2,4-di-t-butylphenyl) phosphite is particularly suitable, and is commercially available as, for example, Irgafos 168 manufactured by BASF ("Irgafos" is a registered trademark of BASF Societas Europea).

[0049] The phosphorus-based antioxidant (D) preferably contains, for example, a compound represented by the following formula (3).

[0050] Formula (3): [ka] (In the formula, R 2 , R 3 , R 5 and R 6 R each independently represents 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. 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 - (where 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 - (where R 8represents 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.

[0051] In formula (3), R 2 , R 3 , R 5 and R 6 each independently represents 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.

[0052] Here, examples of the alkyl group 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 the cycloalkyl group having 5 to 8 carbon atoms include cyclopentyl, cyclohexyl, cycloheptyl, and cyclooctyl groups. Examples of the alkylcycloalkyl group having 6 to 12 carbon atoms include 1-methylcyclopentyl, 1-methylcyclohexyl, and 1-methyl-4-i-propylcyclohexyl groups. Examples of the aralkyl group having 7 to 12 carbon atoms include benzyl, α-methylbenzyl, and α,α-dimethylbenzyl groups.

[0053] R 2 , R 3 and R 5 are each preferably 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. 2 and R 5 are each preferably 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. 3is preferably 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 more preferably a methyl group, a t-butyl group, or a t-pentyl group.

[0054] R 6 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.

[0055] 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 above-mentioned 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.

[0056] In formula (3), X represents a single bond, a sulfur atom, or a group represented by the formula: -CHR 7 -, where the formula is -CHR 7 -R in 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 above-mentioned R 2 , R 3 , R 5 and R 6 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.

[0057] In formula (3), A is an alkylene group having 1 to 8 carbon atoms or a group represented by the formula: 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. 8 -R in 8 R represents a single bond or an alkylene group having 1 to 8 carbon atoms. 8 Examples of the alkylene group having 1 to 8 carbon atoms represented by the formula (I) include the alkylene groups exemplified in the description of A above. 8 is preferably a single bond or an ethylene group. 8 The * in - is a bond on the oxygen side, indicating that the carbonyl group is bonded to the oxygen atom of the phosphite group.

[0058] 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 above-mentioned R 2 , R 3 , R 5 and R 6 Examples of the alkyl group include those exemplified in the explanation of the above.

[0059] Examples of the compound 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, 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, and the like. 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 manufactured by Sumitomo Chemical Co., Ltd. ("Sumilizer" is a registered trademark).

[0060] The phosphorus-based antioxidant (D) preferably contains, for example, a compound represented by the following formula (4).

[0061] Formula (4): [ka] (In the formula, R 9 and R 10 each independently represents 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.

[0062] Examples of the compound represented by formula (4) include bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite, phenyl bisphenol A pentaerythritol diphosphite, etc. Bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite is commercially available under the trade name "ADK STAB PEP-24G" manufactured by ADEKA CORPORATION. ADK STAB PEP-36 ("ADK STAB" is a registered trademark) manufactured by ADEKA CORPORATION is commercially available.

[0063] The phosphorus-based antioxidant (D) preferably contains, for example, a compound represented by the following formula (5).

[0064] Formula (5): [ka]

[0065] (In the formula, R 11 ~R 18 R each independently represents an alkyl group or an alkenyl group having 1 to 3 carbon atoms. 11 and R 12 , R 13 and R 14 , R 15 and R 16 , R 17 and R 18 may be bonded to each other to form a ring. 19 ~R 22 each independently represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms. d to g each independently represents an integer of 0 to 5. X 1 ~X 4 Each of X independently represents a single bond or a carbon atom. 1 ~X 4 is a single bond, R 11 ~R 22 Among these, the functional group connected to the single bond is excluded from the general formula (5).

[0066] 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.

[0067] The above-mentioned aromatic polycarbonate resin composition is preferably one that 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.

[0068] It is preferred 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 mass%, more preferably 30 to 80 mass%, and particularly preferably 40 to 70 mass% of the total amount of the phosphorus-based antioxidant (D).

[0069] The amount of the 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, based on 100 parts by weight of the aromatic polycarbonate resin (A). If the amount of the phosphorus-based antioxidant (D) is less than 0.005 parts by weight, the effect of improving the light transmittance or hue is insufficient. Conversely, if the amount of the phosphorus-based antioxidant (D) is more than 0.5 parts by weight, the effect of improving the light transmittance or hue is also insufficient.

[0070] The aromatic polycarbonate resin composition according to the embodiment of the present invention more 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): By using the fatty acid ester (B), the light diffusing agent (C), the phosphorus-based antioxidant (D), and the aromatic compound (E) in this manner, 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 for a light-diffusing molded article.

[0071] For example, thermal deterioration (clouding or coloring) of an optical molded article molded from an aromatic polycarbonate resin composition caused by long-term light irradiation from a light source (such as an LED light source) is effectively prevented. When a light-diffusing molded article 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 article may increase, and thermal deterioration 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 an aromatic polycarbonate resin composition used in a normal light-diffusing molded article, and clouding or coloring (light to dark coloring) may occur on the surface of the molded article.

[0072] In view of this problem, the present inventors conducted extensive 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 denaturation 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 the molded article can be inhibited and the phenomenon of clouding or coloring (light to dark coloring) can be reduced or alleviated. Formula (1): [ka]

[0073] The amount of the 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 the aromatic polycarbonate resin (A). In order to obtain the effect of suppressing the modification of the fatty acid ester (B) by the aromatic compound (E), the amount of the aromatic compound (E) is set to 0.0001 parts by weight or more per 100 parts by weight of the aromatic polycarbonate resin (A). The amount of the 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 the aromatic polycarbonate resin (A). When the amount of the aromatic compound (E) is less than 0.0001 parts by weight, the effect of suppressing clouding or coloring is insufficient. Conversely, when the amount of the aromatic compound (E) exceeds 0.003 parts by weight, it is not desirable because it may not be possible to achieve a high level of light transmittance and hue required for the optical molded product.

[0074] In the present invention, for example, an ultraviolet absorber, which is a component that further improves the weather resistance of the aromatic polycarbonate resin composition obtained, can be appropriately used in the aromatic polycarbonate resin composition according to the embodiment, depending on the application of the molded article obtained by molding the aromatic polycarbonate resin composition.

[0075] As the ultraviolet absorbent, for example, ultraviolet absorbents 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.

[0076] 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. Examples of such benzotriazole include 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, and 2,2'-Methylenbis[6-(2H-benzotriazol-2-yl)4-(1,1,3,3-tetramethylbutyl)phenol]. Among these, 2-(2-hydroxy-5-t-octylphenyl)benzotriazole is particularly suitable, and examples of such benzotriazole 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., which are commercially available.

[0077] 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.

[0078] As the oxalic acid anilide compound, for example, Sanduvor VSU manufactured by Clariant Japan K.K. and the like are commercially available.

[0079] Examples of benzophenone compounds include 2,4-dihydroxybenzophenone and 2-hydroxy-4-n-octoxybenzophenone.

[0080] The amount of the ultraviolet absorber is 0 to 1.0 part by weight, preferably 0 to 0.5 part by weight, based on 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 color of the resulting aromatic polycarbonate resin composition may be deteriorated. In addition, 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 great.

[0081] The aromatic polycarbonate resin composition according to the embodiment of the present invention can 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, the excellent optical properties required for the light-diffusing molded article are maintained and improved, and the initial optical properties of the molded article made of the obtained aromatic polycarbonate resin composition are not deteriorated, and deterioration due to the usage conditions and aging deterioration can be prevented.

[0082] 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, etc. The epoxy compound (F) preferably includes 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate.

[0083] The aromatic polycarbonate resin composition of the present invention preferably contains 0.001 to 0.2 parts by weight of an epoxy compound relative to 100 parts by weight of a linear aromatic polycarbonate resin, more preferably 0.002 to 0.1 parts by weight, and particularly preferably 0.005 to 0.05 parts by weight. When the aromatic polycarbonate resin composition of the present invention contains 0.001 to 0.2 parts by weight of an epoxy compound relative to 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) of a molded product made of the obtained 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 the usage conditions and deterioration due to aging.

[0084] Furthermore, the aromatic polycarbonate resin composition according to the embodiment may appropriately contain various additives such as a heat stabilizer, other antioxidants, colorants, release agents, softeners, antistatic agents, and impact modifiers, as well as polymers other than linear aromatic polycarbonate resins, within the scope that does not impair the effects of the present invention.

[0085] The aromatic polycarbonate resin composition according to 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 thereof include a method of mixing using a known mixer such as a tumbler or a ribbon blender, and a method of melt-kneading using an extruder. These methods can easily produce pellets of the aromatic polycarbonate resin composition. The aromatic compound (E) may be mixed before melt-kneading, or may be added or mixed in advance to the fatty acid ester (B).

[0086] The shape and size of the pellets of the aromatic polycarbonate resin composition obtained as described above are not particularly limited, and may be any shape and size that a typical resin pellet has. 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 such a size, or all the pellets forming the pellet aggregate may be of such a size, or the average value of the pellet aggregate may be of such a size, and there is no particular limitation.

[0087] 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-diffusing plate (particularly a light-diffusing plate for an image display device), the surface area is preferably 500 to 50,000 cm. 2 The surface area of ​​the light diffusion plate is 1000 to 25000 cm. 2and the thickness is preferably 0.3 to 3 mm. In this manner, the aromatic polycarbonate resin composition of the present invention can produce a large light diffusion plate that has high dimensional stability and is thin (lightweight).

[0088] As long as the light-diffusing molded article intended by the present invention can be obtained, the method for producing the light-diffusing molded article is not particularly limited, and examples thereof include a method for molding an aromatic polycarbonate resin composition by a known injection molding method, compression molding method, etc.

[0089] Examples of the light-diffusing molded article according to the present invention include light diffusion plates, light diffusion films, electronic and electrical devices, parts of office automation devices, 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 (a light diffusion plate used in a backlight module of a liquid crystal display device or the like, a light diffusion plate used in a screen of a projection type display device such as a projector television, etc.), etc. For the backlight module of a liquid crystal display device or the like, various light sources (cold cathode fluorescent lamps, LEDs, etc.) can be used.

[0090] As described above, the embodiments of the present invention have been described as examples of the present invention. However, the technology of the present invention is not limited to the above, and can be applied to embodiments in which appropriate changes, substitutions, additions, omissions, etc. are made. EXAMPLES

[0091] 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.

[0092] 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.

[0093] 2. Fatty acid ester (B): Glycerin monostearate (GMS), manufactured by Riken Vitamin Co., Ltd., product name Rikemal S-100A

[0094] 3. Light diffusing agent (C): 3-1. Polymethylsilsesquioxane-based diffusing agent Tospearl 120S (product name) manufactured by Momentive, hereinafter referred to as (C1). 3-2. Acrylic diffusing agent GM-0449S (product name) manufactured by Ganz Chemical Co., Ltd., hereinafter also referred to as (C2). 3-3. Styrene-methyl methacrylate copolymer crosslinked particles SMX-12R (product name) manufactured by Sekisui Chemical Co., Ltd., hereinafter also referred to as (C3).

[0095] 4. Phosphorus-based antioxidants (D): 4-1. Tris(2,4-di-t-butylphenyl)phosphite, represented by the following formula: [ka] Irgafos 168 (product name) manufactured by BASF, hereinafter also referred to as (D1).

[0096] 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: [ka] ADEKA STAB PEP-36 (product name), hereinafter also referred to as (D2). 5.Aromatic compounds (E):

[0097] 3,5-Di-t-butyl-4-hydroxytoluene (BHT) Manufactured by Wako Pure Chemical Industries, Ltd. (hereinafter referred to as (E)).

[0098] 6. Epoxy compounds (F): 3',4'-Epoxycyclohexylmethyl-3,4-epoxycyclohexylcarboxylate Celloxide 2021P (product name) manufactured by Daicel Chemical Industries, Ltd.

[0099] (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.

[0100] Using the obtained pellets, evaluation specimens were prepared according to the following method and subjected to evaluation. The results are shown in Tables 1 and 2.

[0101] (How to prepare test specimens) The pellets obtained were dried at 120°C for 4 hours or more, and then an injection molding machine (FANUC, ROBOSHOT S2000i100A) was used to prepare a 3-stage plate-shaped test piece 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) at a molding temperature of 290°C and a mold temperature of 80°C.

[0102] (Test piece evaluation method) 1.Total light transmittance (%): The total light transmittance was measured in accordance with JIS K7361 using a 1 mm section of the obtained three-step plate-shaped test piece. The higher the value, the better the light transmittance of the molded product. A total light transmittance value of 40% or more for a molded product with a thickness of 1 mm was considered good.

[0103] 2.Light diffusion degree (degrees): Using a 1 mm section of the three-step plate-shaped test piece used in 1 above, the light diffusion (D50) was determined using an automatic variable angle photometer (Goniophotometer GP-1R, manufactured by Murakami Color Research Laboratory). The detailed measurement method is as follows. The larger this value, the better the light diffusion of the molded product. A straight beam from the light source of the automatic variable angle photometer was applied to the test piece in the normal direction, the intensity of the transmitted light was measured using a movable light receiver, and the transmittance was plotted against the angle from the normal direction to determine the angle (D50) at which the transmittance was 50% of the straight light transmittance. The unit is "degrees," and a light diffusion (D50) of 30 degrees or more was considered good.

[0104] 3. Prevention of light source see-through (visual judgment): A rectangular hole measuring 3cm x 5cm was drilled in the center of a Philips 20W straight tube LED lamp, and a 3cm x 5cm x 1mm injection molded plate was placed in that area at a height of approximately 1.5cm from the LED light source. The light source visibility prevention was judged visually from a height of approximately 20cm above the injection molded plate placed on the LED lamp. If the light had sufficient light diffusion and the outline of the LED light source had disappeared, it was judged as extremely good ◎. If the outline of the LED light source was somewhat visible, it was judged as good ○, and if there was poor light diffusion and the outline of the LED light source was clearly visible, it was judged as poor ×.

[0105] 4.Yellowness: Using a 1 mm portion of the obtained three-step plate-shaped test piece, the yellowness index (hereinafter, YI) of each test piece after the heating test was determined using a spectrophotometer (UH4150, manufactured by Hitachi, Ltd.) with a standard light source of D65 and a 10-degree visual field. The heating test was performed by placing the above test piece in an inert oven IPHH-201M manufactured by Espec Corporation and holding it at 90°C for 500 hours. Note that a YI of 3.5 or less was considered good (indicated by ◎ in the table), a YI of more than 3.5 and 4.0 or less was considered usable (indicated by ○ in the table), and a YI of more than 4.0 was considered poor (indicated by × in the table).

[0106] Table 1 shows the raw materials and mixing ratios of each of the examples and comparative examples, as well as the evaluation results.

[0107] [Table 1]

[0108] 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, low yellowness, and are hardly deteriorated after a heating test.

[0109] Furthermore, molded articles produced from such aromatic polycarbonate resin compositions have a low yellowness index and excellent hue, and furthermore, are hardly deteriorated after a heating test.

[0110] In contrast, the aromatic polycarbonate resin composition of Comparative Example 1 had a low light diffusion rate and poor light source visibility prevention because of a low blending amount of the light diffusion agent. The aromatic polycarbonate resin composition of Comparative Example 2 had a low total light transmittance and high yellowness index before and after the heating test because of a high blending amount of the light diffusion agent. The aromatic polycarbonate resin composition of Comparative Example 3 had a high yellowness index after the heating test because of a high amount of the phosphorus-based antioxidant.

[0111] The embodiments have been described above as examples of the technology of the present invention, and detailed descriptions have been provided for this purpose.

[0112] Therefore, the components described in the detailed description may include not only essential components 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 those non-essential components are described in the detailed description should not be interpreted as immediately being essential.

[0113] Furthermore, since the above-described embodiment is intended to illustrate the technology of the present invention, various modifications, substitutions, additions, omissions, and the like can be made within the scope of the claims or their equivalents. [Industrial Applicability]

[0114] The polycarbonate resin composition of the present invention does not lose the inherent properties of polycarbonate resin such as heat resistance and mechanical strength, has excellent thermal stability, and is high in transparency, light transmittance, and light diffusion. Moreover, even if the obtained molded article is exposed for a long period of time under high temperature conditions due to a hot sun environment and / or light source irradiation, the transparency and transmittance are not likely to decrease (there is little clouding or coloring). Therefore, even if the molded article (diffusion plate) has a thickness of about 0.3 mm, the hue is not likely to change and the appearance is not likely to deteriorate (deteriorate), and even if the molded article 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 (there is little clouding or coloring), that is, a polycarbonate resin composition having 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 the industrial value of the composition is extremely high.

Claims

1. 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): [Case 1]

2. 2. 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.

3. 3. The aromatic polycarbonate resin composition according to claim 2, wherein the fatty acid ester (B) comprises an ester of an aliphatic monocarboxylic acid or an aliphatic dicarboxylic acid having 6 to 36 carbon atoms and an aliphatic saturated monohydric alcohol or an aliphatic saturated polyhydric alcohol having 30 or less carbon atoms.

4. 4. The aromatic polycarbonate resin composition according to claim 3, wherein the fatty acid ester (B) is glycerin monostearate.

5. 2. 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.

6. 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: [Case 2]

7. 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): [C3] [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): [C5] [In the formula, R ９ , R １０ represents 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 represent integers of 0 to 3.

8. 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.

9. 9. 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).

10. 9. The aromatic polycarbonate resin composition according to claim 8, wherein the phosphorus-based antioxidant (D) contains at least two types of 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).

11. 2. 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.

12. A light-diffusing molded article comprising the aromatic polycarbonate resin composition according to any one of claims 1 to 11.

13. The light-diffusing molded article according to claim 9, which is a light-diffusing plate or film for an image display device.