Polycarbonate resin composition and molded article

Abstract

To provide a polycarbonate resin composition having excellent transparency and small birefringence.SOLUTION: The polycarbonate resin composition contains, based on 100 pts.mass of a polycarbonate resin (A), 5-45 pts.mass of a styrenic resin (B) having a refractive index higher than that of the polycarbonate resin (A) and 5-45 pts.mass of a styrene-acrylonitrile copolymer (C) having a refractive index lower than that of the polycarbonate resin (A).SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to a polycarbonate resin composition, and more particularly to a polycarbonate resin composition having excellent transparency and low birefringence, and a molded article thereof.

Background Art

[0002] Polycarbonate resins are excellent in impact resistance, heat resistance, electrical insulation, dimensional stability, etc., and have a good balance of these properties, so they are widely used in various fields. In particular, polycarbonate resins made from bisphenol compounds are excellent in transparency, impact resistance, and heat resistance, and have the advantage of being light and difficult to break, so they are used as alternative materials for glass in automotive parts, building materials, and optical parts such as lenses. In recent years, they have also been widely used as panel members for display devices used in various portable terminals such as smartphones, tablet computers, car navigation systems, car audio systems, portable game machines, digital cameras, etc., especially as front members such as touch panels.

[0003] When considering a resin as an optical member, in addition to transparency, birefringence is an important optical property. Even if it has excellent transparency, it is not preferable to have a large birefringence. In particular, in various display devices such as cameras and liquid crystal display panels, and projectors, when an optical member with a large birefringence exists in the optical path, it will have an adverse effect on image quality and signal reading performance, so a transparent resin with birefringence suppressed as small as possible is strongly required. Since general polycarbonate resins have a large birefringence, for example, in the front member of a display device, if the birefringence is large, phase difference unevenness will occur, causing an iridescent pattern, or when viewing the screen through polarized sunglasses, the iridescent pattern will become even more severe and unviewable, etc., resulting in problems such as a significant decrease in visibility and design (appearance). Polycarbonate resins made from general-purpose bisphenol A as a raw material have a large birefringence, and this problem is prominent.

[0004] Conventionally, various methods have been studied to reduce the birefringence of polycarbonate resins. It is known to use a polycarbonate resin with a bisphenol of a specific structure for the resin itself. For example, in Patent Document 1, it is disclosed that a special polycarbonate copolymer obtained by copolymerizing spirobisindane bisphenol with bisphenol A has low birefringence. However, since such a special resin is not a general-purpose resin, its properties (mechanical properties) and molding conditions become special, and there are also limitations in its use in terms of price.

[0005] In addition, a technique has also been proposed to reduce birefringence by blending a resin having a positive birefringence property of a polycarbonate resin with a resin having a negative birefringence property. The applicant of the present application proposed in Patent Document 2 that a resin composition in which a styrene-based resin (B), specifically a styrene-maleic anhydride copolymer (SMA resin), having an α,β-unsaturated dicarboxylic anhydride or a derivative thereof as a copolymerization component is blended with a polycarbonate resin (A) has low birefringence. However, this does not necessarily achieve a good balance between transparency and low birefringence at a high level required for recent high-end products.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] Mixing a resin having negative birefringence such as the above-described SMA resin with a polycarbonate resin having positive birefringence characteristics is effective for improving birefringence. However, the SMA resin is basically incompatible with the polycarbonate resin, and the resulting resin composition forms a morphology in which the SMA resin exists in an island shape in the sea of the polycarbonate resin matrix. Since there is a difference in the refractive index between the two, the light incident on the island of the SMA resin is refracted and scattered instead of traveling straight, resulting in a decrease in transparency (haze). The present invention has been made in view of the above-described situation, and an object (problem) thereof is to provide a polycarbonate resin composition and a molded article thereof that are excellent in transparency (haze) and have low birefringence.

Means for Solving the Problem

[0008] As a result of intensive studies to solve the above object (problem), the present inventor combined two types of styrene resins having a refractive index higher than that of the polycarbonate resin and a styrene-acrylonitrile copolymer having a refractive index lower than that of the polycarbonate resin, and made the refractive index the same as that of the polycarbonate resin, and found that low birefringence can be achieved and the above problem can be solved. The present invention relates to the following polycarbonate resin composition and molded article.

[0009] 1. A polycarbonate resin composition characterized by containing 5 to 45 parts by mass of a styrene resin (B) having a refractive index higher than that of the polycarbonate resin (A) and 5 to 45 parts by mass of a styrene-acrylonitrile copolymer (C) having a refractive index lower than that of the polycarbonate resin (A) with respect to 100 parts by mass of the polycarbonate resin (A). 2. The polycarbonate resin composition according to the above 1, wherein the styrene resin (B) is a styrene-maleic anhydride copolymer. 3. The polycarbonate resin composition according to the above 1 or 2, wherein the polycarbonate resin (A) includes a polycarbonate resin having a structural unit represented by the following general formula (1).

Chemical formula

[0010] 4. The polycarbonate resin composition according to any one of the above 1 to 3, wherein the haze of a 1 mm thick molded product formed from the resin composition is 5% or less. 5. The polycarbonate resin composition according to any one of the above 1 to 4, wherein birefringence is reduced. 6. A molded article comprising the polycarbonate resin composition according to any one of the above 1 to 5. 7. The molded article according to the above 6, which is an optical molded article. 8. The molded article according to the above 6 or 7, which is a front member of a display panel. [Advantages of the Invention]

[0011] The styrene-acrylonitrile copolymer (C) contained in the polycarbonate resin composition of the present invention has negative birefringence and a refractive index lower than that of the polycarbonate resin (A). The styrene resin (B) has a higher refractive index than the polycarbonate resin (A) and has negative birefringence. The refractive index difference of the components (B) and (C) with respect to the polycarbonate resin (A) is about the same. Since the components (B) and (C) are compatible, they are compatibilized and form island-like portions having a refractive index equivalent to that of the polycarbonate resin (A) in the matrix (sea) of the polycarbonate resin (A). As a result, it is considered that excellent transparency can be achieved, and by sufficiently canceling the positive birefringence of the polycarbonate resin (A), both transparency and low birefringence can be achieved simultaneously at a high level.

Mode for Carrying Out the Invention

[0012] Hereinafter, each component and the like constituting the polycarbonate resin composition of the present invention will be described in detail. In the present specification, when a range is expressed using "~" with numerical values or physical property values sandwiching the front and back thereof, it means a range including the values before and after.

[0013] The polycarbonate resin composition of the present invention contains 5 to 45 parts by mass of a styrene resin (B) having a refractive index higher than that of the polycarbonate resin (A) and 5 to 45 parts by mass of a styrene-acrylonitrile copolymer (C) having a refractive index lower than that of the polycarbonate resin (A) with respect to 100 parts by mass of the polycarbonate resin (A).

[0014] [Polycarbonate Resin (A)] As the polycarbonate resin (A), an aromatic polycarbonate resin having an aromatic ring in the main chain is preferable in terms of a large effect of reducing birefringence.

[0015] The aromatic polycarbonate resin is an aromatic polycarbonate polymer obtained by reacting an aromatic hydroxy compound with phosgene or a diester of carbonic acid. The aromatic polycarbonate polymer may have a branch. The production method of the aromatic polycarbonate resin is not particularly limited, and it can be carried out by a conventional method such as the phosgene method (interfacial polymerization method) or the melting method (transesterification method).

[0016] Typical examples of the aromatic dihydroxy compound include 2,2-bis(4-hydroxyphenyl)propane (that is, bisphenol A) and the like.

[0017] Particularly preferred aromatic polycarbonate resins used in the present invention include a polycarbonate resin (A1) having a structural unit represented by the following general formula (1) in that it is likely to have the same refractive index level as the styrene resin (B) and the styrene-acrylonitrile copolymer (C). [Chemical formula] (In general formula (1), R 1 represents a methyl group, R 2 and R 3 each independently represent a hydrogen atom or a methyl group, and X represents [Chemical formula] any one of them, and R 4 and R 5 each independently represent a hydrogen atom or a methyl group, and Z represents a group that forms an alicyclic hydrocarbon having 6 to 12 carbon atoms which may have a substituent and is bonded to a carbon atom C.)

[0018] In the above general formula (1), R 1 is a methyl group, R 2 and R 3 each independently represent a hydrogen atom or a methyl group, but R 2 and R 3 are particularly preferably hydrogen atoms.

[0019] Also, when X is [Chemical formula] it is preferably an isopropylidene group in which both R 4 and R 5 are methyl groups. Also, when X is [Chemical formula] In the case where Z is bonded to the carbon atom C that is bonded to the two phenyl groups in the general formula (1) above to form a divalent alicyclic hydrocarbon group having 6 to 12 carbon atoms, examples of such a divalent alicyclic hydrocarbon group include cycloalkylidene groups such as cyclohexylidene group, cycloheptylidene group, cyclododecylidene group, and adamantylidene group. Substituted ones include those having a methyl substituent or an ethyl substituent on these. Among these, a cyclohexylidene group, a methyl-substituted product of a cyclohexylidene group (preferably a 3,3,5-trimethyl-substituted product), and a cyclododecylidene group are preferred.

[0020] Preferred specific examples of the polycarbonate resin (A1) represented by the general formula (1) above include the following polycarbonate resins (i) to (ii). (i) Those having a 2,2-bis(3-methyl-4-hydroxyphenyl)propane structural unit, that is, those in which R 1 is a methyl group, R 2 and R 3 are hydrogen atoms, and X is an isopropylidene group, and those having a structural unit derived from bisphenol C. (ii) A 2,2-bis(3-methyl-4-hydroxyphenyl)cyclododecane structural unit, that is, those in which R 1 is a methyl group, R 2 and R 3 are hydrogen atoms, and X is a cyclododecylidene group. (iii) A 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane structural unit, that is, those in which R 1 is a methyl group, R 2 and R 3 are methyl groups, and X is an isopropylidene group. (ii) A 2,2-bis(3-methyl-4-hydroxyphenyl)cyclohexane structural unit, that is, those in which R 1 is a methyl group, R 2 and R 3 are hydrogen atoms, and X is a cyclohexylidene group. Among these, more preferably, the above (a), (b) or (c), still more preferably the above (a) or (b), and particularly preferably the polycarbonate resin of the above (a) is preferred.

[0021] These polycarbonate resins can each be produced by using 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)cyclododecane, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, or 2,2-bis(3-methyl-4-hydroxyphenyl)cyclohexane as a dihydroxy compound.

[0022] The polycarbonate resin (A1) may be a copolymer polycarbonate resin having carbonate units other than those represented by the above general formula (1). Examples of the dihydroxy compound as a raw material for other carbonate units include the following aromatic dihydroxy compounds. 2,2-bis(4-hydroxyphenyl)propane, bis(4-hydroxyphenyl)methane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxyphenyl)pentane, 2,2-bis(4-hydroxyphenyl)-4-methylpentane, 1,1-bis(4-hydroxyphenyl)decane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)phenylmethane, 1,1-bis(4-hydroxyphenyl)cyclopentane, 1,1-bis(4-hydroxyphenyl)cyclooctane, 9,9-bis(4-hydroxyphenyl)fluorene, 4,4'-dihydroxybenzophenone, 4,4'-dihydroxyphenyl ether, etc.

[0023] When it is a copolymer polycarbonate resin, the structural unit represented by the above general formula (1) is preferably more than 50 mol%, more preferably 70 mol% or more, still more preferably 80 mol% or more, particularly preferably 90 mol% or more, and especially preferably 95 mol% or more.

[0024] The polycarbonate resin (A1) may be used alone, or two or more types may be used in combination at any ratio and in any combination.

[0025] When using the polycarbonate resin (A1) as the polycarbonate resin (A), it is also preferable to use it in combination with another polycarbonate resin (A2) other than the polycarbonate resin (A1). As the other polycarbonate resin (A2), a polycarbonate resin using 2,2-bis(4-hydroxyphenyl)propane (that is, bisphenol A) as a starting material is particularly preferable.

[0026] When the polycarbonate resin (A) contains another polycarbonate resin (A2) together, its content is preferably less than 50% by mass, more preferably 40% by mass or less, still more preferably 30% by mass or less, especially 25% by mass or less, 20% by mass or less, and particularly preferably 15% by mass or less in 100% by mass of the polycarbonate resin (A). Here, even when the polycarbonate resin (A1) contains a unit derived from bisphenol A as a copolymerization unit, as long as it has the structural unit represented by the general formula (1), it is treated as the polycarbonate resin (A1).

[0027] The refractive index of the polycarbonate resin (A) is not limited as long as it is between that of the styrene resin (B) and the styrene-acrylonitrile copolymer (C), but is preferably about 1.575 to 1.585. Note that the polycarbonate resin (A) may be used by mixing two or more types of polycarbonate resins having different refractive indices. In this case, a polycarbonate resin having a refractive index outside the above preferred range may be mixed and adjusted to the above range.

[0028] In the present invention, the refractive indices of each resin such as polycarbonate resin (A), styrene resin (B), styrene resin (B2), and styrene-acrylonitrile copolymer (C) are values measured at a temperature of 23 ± 1°C, a humidity of 50 ± 5% RH, and a 589 nm sodium D line in accordance with JIS K7142.

[0029] The viscosity average molecular weight Mv of the polycarbonate resin (A) is preferably in the range of 10,000 to 50,000, more preferably 45,000 or less, still more preferably 40,000 or less, and particularly preferably 38,000 or less. In the case of an optical molded article, it is preferably 10,000 to 30,000. When the viscosity average molecular weight is in such a range, it is excellent in fluidity (molding processability), hue, and mechanical strength, and is suitable for an optical molded article. Note that two or more polycarbonate resins having different viscosity average molecular weights may be mixed and used. In this case, a polycarbonate resin having a viscosity average molecular weight outside the above preferred range may be mixed.

[0030] The viscosity average molecular weight Mv of the polycarbonate resin (A) is determined by using methylene chloride as a solvent and measuring the intrinsic viscosity [η] (unit: dl / g) at a temperature of 25°C using an Ubbelohde viscometer, and calculating the value from the Schnell viscosity formula, η = 1.23×10 -4 Mv 0.83 It means the value calculated from. The intrinsic viscosity [η] is a value measured for the specific viscosity [η sp at each solution concentration [C] (g / dl) and calculated by the following formula.

Equation

[0031] [Styrene resin (B)] The styrene resin (B) contained in the resin composition of the present invention is a styrene resin having a refractive index higher than that of the polycarbonate resin (A1). As described above, the refractive index of the polycarbonate resin (A) is preferably in the range of 1.575 to 1.585, but the styrene resin (B) has a higher refractive index than this. When the refractive index of the polycarbonate resin (A) is nA and the refractive index of the styrene resin (B) is nB, it is preferable that nB - nA is greater than 0 and 0.05 or less, more preferably 0.04 or less, and still more preferably 0.03 or less.

[0032] As long as the styrene resin (B) has a refractive index higher than that of the polycarbonate resin (A), various styrene resins can be used. To adjust the refractive index of the styrene resin, it is possible by various known methods. For example, there is a method of adjusting the type and copolymerization ratio of the styrene monomer and the monomer copolymerizable therewith. It is also possible to estimate the calculated value of the refractive index from the molecular refraction and molecular volume of the monomer constituent units. Further, it is also possible to select and use a styrene resin having such a refractive index from commercially available products.

[0033] The styrene resin (B) is a resin obtained by polymerizing one or more selected from styrene monomers and, if necessary, other vinyl monomers copolymerizable therewith.

[0034] Examples of the styrene monomer include styrene derivatives such as styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, vinylxylene, ethylstyrene, dimethylstyrene, p-tert-butylstyrene, and vinylnaphthalene. Styrene is particularly preferable. These may be used alone or in combination of two or more.

[0035] Examples of other vinyl monomers copolymerizable with styrene monomers include α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, phthalic acid, and itaconic acid and their anhydrides; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, amyl methacrylate, hexyl methacrylate, 2-ethylhexyl methacrylate, octyl methacrylate, cyclohexyl methacrylate, and dodecyl methacrylate; alkyl acrylates such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, amyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, cyclohexyl acrylate, and dodecyl acrylate; aryl acrylates such as phenyl acrylate and benzyl acrylate; aryl methacrylates such as phenyl methacrylate and benzyl methacrylate; and maleimide monomers such as maleimide, N-methylmaleimide, and N-phenylmaleimide. These vinyl monomers may be used alone or in combination of two or more. Among these, α,β-unsaturated carboxylic acids such as methacrylic acid, maleic acid, and maleic anhydride and their anhydrides, alkyl acrylates, alkyl methacrylates, and maleimide monomers such as N-phenylmaleimide are preferred.

[0036] Preferred styrenic resins (B) include styrene-maleic anhydride copolymers (SMA resins), polystyrene, and styrene-N-phenylmaleimide copolymers, and particularly preferred is styrene-maleic anhydride copolymer.

[0037] The content of the styrene resin (B) is 5 to 45 parts by mass with respect to 100 parts by mass of the polycarbonate resin (A). By containing it within such a range together with the styrene-acrylonitrile copolymer (C), transparency and low birefringence of the resin composition can be achieved. The content of the styrene resin (B) is preferably 7 parts by mass or more, more preferably 10 parts by mass or more, preferably 42 parts by mass or less, and more preferably 40 parts by mass or less.

[0038] [styrene-acrylonitrile copolymer (C)] The polycarbonate resin composition of the present invention contains a styrene-acrylonitrile copolymer (C) having a refractive index lower than that of the polycarbonate resin (A). When the refractive index of the polycarbonate resin (A) is nA and the refractive index of the styrene-acrylonitrile copolymer (C) is nC, it is preferable that nA - nC is greater than 0 and 0.05 or less, more preferably 0.04 or less, and even more preferably 0.03 or less. The styrene-acrylonitrile copolymer (C) is a copolymer of acrylonitrile and a styrene monomer.

[0039] Examples of the styrene monomer constituting the styrene-acrylonitrile copolymer (C) include styrene, α-methylstyrene, p-methylstyrene, vinylxylene, ethylstyrene, dimethylstyrene, p-tert-butylstyrene, vinylnaphthalene, methoxystyrene, monobromostyrene, dibromostyrene, fluorostyrene, tribromostyrene, etc. Styrene and α-methylstyrene are more preferable, and styrene is particularly preferable.

[0040] As long as the styrene-acrylonitrile copolymer (C) has a refractive index lower than that of the polycarbonate resin (A), it may be a copolymer with other copolymerizable monomers other than acrylonitrile and the styrene monomer. Examples of copolymerizable monomers other than styrene monomers and acrylonitrile include (meth)acrylate monomers, maleimide monomers such as maleimide, N-methylmaleimide, and N-phenylmaleimide, and α,β-unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, phthalic acid, and itaconic acid, and their anhydrides.

[0041] In the styrene-acrylonitrile copolymer (C), the amount of units derived from styrene is preferably 75% by mass or more based on 100% by mass in total. By setting the amount of units derived from styrene in the copolymer (C) to 75% by mass or more, it becomes possible to achieve higher transparency and a lower birefringence value (retardation).

[0042] The amount of units derived from styrene is more preferably 77% by mass or more, still more preferably 78% by mass or more, preferably 95% by mass or less, more preferably 92% by mass or less, still more preferably 90% by mass or less, particularly preferably 88% by mass or less, and especially preferably 85% by mass or less. The amount of units derived from acrylonitrile monomer is preferably 25% by mass or less, more preferably 23% by mass or less, still more preferably 22% by mass or less, preferably 5% by mass or more, more preferably 8% by mass or more, still more preferably 10% by mass or more, particularly preferably 12% by mass or more, and especially preferably 15% by mass or more. The styrene-acrylonitrile copolymer (C) is a copolymer and does not contain a styrene homopolymer. Styrene homopolymer (polystyrene) has poor transparency and it is difficult to impart good transparency.

[0043] When the styrene-acrylonitrile copolymer (C) is a copolymer of acrylonitrile and other copolymerizable monomers other than styrene monomers, the amount of units derived from other copolymerizable monomers other than styrene monomers and acrylonitrile is preferably 30% by mass or less based on 100% by mass of the copolymer (C), more preferably 20% by mass or less, still more preferably 10% by mass or less, particularly preferably 5% by mass or less, 3% by mass or less, 2% by mass or less, and especially preferably 1% by mass or less.

[0044] The styrene-acrylonitrile copolymer (C) is preferably an acrylonitrile-styrene resin composed of acrylonitrile and styrene, which is usually also referred to as an AS resin.

[0045] There is no limitation on the method for producing the styrene-acrylonitrile copolymer (C), and known methods can be adopted. For example, methods such as bulk polymerization, emulsion polymerization, solution polymerization, and suspension polymerization can be used.

[0046] The content of the styrene-acrylonitrile copolymer (C) is 5 to 45 parts by mass with respect to 100 parts by mass of the polycarbonate resin (A). By containing it within such a range together with the styrene resin (B), transparency (haze) and low birefringence can be achieved at a high level. If the total content of the styrene resin (B) and the styrene-acrylonitrile copolymer (C) is less than 10 parts by mass, the effect of improving birefringence is low. If it exceeds 90 parts by mass, in addition to the deterioration of haze, the heat resistance is likely to decrease. The content of the styrene-acrylonitrile copolymer (C) is preferably 7 parts by mass or more, more preferably 10 parts by mass or more, preferably 42 parts by mass or less, more preferably 40 parts by mass or less, still more preferably 38 parts by mass or less, and particularly preferably 35 parts by mass or less.

[0047] The total content of the styrene resin (B) and the styrene-acrylonitrile copolymer (C) is preferably 10 to 90 parts by mass, more preferably 13 to 70 parts by mass, with respect to 100 parts by mass of the polycarbonate resin (A).

[0048] [Additives, etc.] The resin composition can contain additives, for example, additives such as ultraviolet absorbers, stabilizers, mold release agents, flame retardants, flame retardant aids (dripping inhibitors), fluorescent brighteners, antistatic agents, plasticizers, and compatibilizers. These additives may be blended singly or in combination of two or more.

[0049] [Ultraviolet Absorber] The polycarbonate resin composition of the present invention preferably contains an ultraviolet absorber. Examples of the ultraviolet absorber include inorganic ultraviolet absorbers such as cerium oxide and zinc oxide; organic ultraviolet absorbers such as benzotriazole compounds, benzophenone compounds, salicylate compounds, cyanoacrylate compounds, triazine compounds, oxanilide compounds, malonic acid ester compounds, and hindered amine compounds. Among these, organic ultraviolet absorbers are preferred, and benzotriazole compounds are more preferred. By selecting an organic ultraviolet absorber, the transparency and mechanical properties of the resin composition of the present invention can be improved.

[0050] Specific examples of the benzotriazole compound include, for example, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-dimethylbenzyl)phenyl]-benzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butyl-phenyl)-benzotriazole, 2-(2'-hydroxy-3'-tert-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-tert-butyl-phenyl)-5-chlorobenzotriazole), 2-(2'-hydroxy-3',5'-di-tert-amyl)-benzotriazole, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole, 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol], etc. Among them, 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole and 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol] are preferred, and particularly 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole is preferred.

[0051] Specific examples of the benzophenone compound include, for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-n-octoxybenzophenone, 2-hydroxy-n-dodecyloxybenzophenone, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, and the like.

[0052] Specific examples of the salicylate compound include, for example, phenyl salicylate, 4-tert-butylphenyl salicylate, and the like. Specific examples of the cyanoacrylate compound include, for example, ethyl-2-cyano-3,3-diphenylacrylate, 2-ethylhexyl-2-cyano-3,3-diphenylacrylate, and the like. Specific examples of the oxanilide compound include, for example, 2-ethoxy-2'-ethyloxalinic acid bisanilide, and the like. As the malonic ester compound, 2-(alkylidene)malonic esters are preferred, and 2-(1-arylalkylidene)malonic esters are more preferred.

[0053] When containing the ultraviolet absorber, the content is usually 0.05 parts by mass or more, preferably 0.1 parts by mass or more, and usually 1 part by mass or less, preferably 0.5 parts by mass or less, based on 100 parts by mass of the polycarbonate resin (A). When the content of the ultraviolet absorber is less than the lower limit value of the above range, the effect of improving weather resistance may be insufficient. When the content of the ultraviolet absorber exceeds the upper limit value of the above range, mold deposits and the like may occur, which may cause mold contamination. One kind of ultraviolet absorber may be contained, or two or more kinds may be contained in any combination and ratio.

[0054] [Stabilizer] The polycarbonate resin composition of the present invention preferably contains a stabilizer, and as the stabilizer, a phosphorus-based stabilizer or a phenol-based stabilizer is preferred.

[0055] As the phosphorus-based stabilizer, any known one can be used. Specific examples include oxo acids of phosphorus such as phosphoric acid, phosphonic acid, phosphorous acid, phosphinic acid, and polyphosphoric acid; metal acid pyrophosphates such as sodium acid pyrophosphate, potassium acid pyrophosphate, and calcium acid pyrophosphate; phosphates of Group 1 or Group 2B metals such as potassium phosphate, sodium phosphate, cesium phosphate, and zinc phosphate; organic phosphate compounds, organic phosphite compounds, and organic phosphonite compounds. Among them, organic phosphite compounds and organic phosphate compounds are particularly preferred.

[0056] Examples of the organic phosphite compound include triphenyl phosphite, tris(monononylphenyl) phosphite, tris(monononyl / dinonylphenyl) phosphite, tris(2,4-di-tert-butylphenyl) phosphite, monooctyldiphenyl phosphite, dioctylmonophenyl phosphite, monodecyldiphenyl phosphite, didecylmonophenyl phosphite, tridecyl phosphite, trilauryl phosphite, tristearyl phosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl) octyl phosphite, and the like.

[0057] As the organic phosphate compound, an organic phosphate metal salt can also be preferably used. Specifically, a mixture of a zinc salt of distearyl acid phosphate and a zinc salt of monostearyl acid phosphate, mono- and di-stearyl acid phosphate, and the like can be mentioned.

[0058] The phosphorus-based stabilizer may be contained alone, or may be contained in any combination and ratio of two or more.

[0059] The content of the phosphorus-based stabilizer is usually 0.001 part by mass or more, preferably 0.01 part by mass or more, more preferably 0.03 part by mass or more, based on 100 parts by mass of the polycarbonate resin (A), and is usually 1 part by mass or less, preferably 0.7 part by mass or less, more preferably 0.5 part by mass or less. When the content of the phosphorus-based stabilizer is less than the lower limit value of the above range, the thermal stability effect may be insufficient. When the content of the phosphorus-based stabilizer exceeds the upper limit value of the above range, the effect may reach a plateau and may become uneconomical.

[0060] Examples of the phenolic stabilizer include hindered phenolic antioxidants. Specific examples thereof include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, thiodiethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], N,N'-hexane-1,6-diylbis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionamide], 2,4-dimethyl-6-(1-methylpentadecyl)phenol, diethyl [[3,5-bis(1,1-dimethylethyl)-4-hydroxyphenyl]methyl]phosphate, 3,3',3",5,5',5"-hexa-tert-butyl-a,a',a"-(mesitylene-2,4,6-triyl)tri-p-cresol, 4,6-bis(octylthiomethyl)-o-cresol, ethylene bis(oxyethylene) bis[3-(5-tert-butyl-4-hydroxy-m-tolyl)propionate], hexamethylene bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-triazine-2,4,6(1H,3H,5H)-trione, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-triazin-2-ylamino)phenol, 2-[1-(2-hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl acrylate, and the like.

[0061] Among them, pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] and octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate are preferable. The phenolic stabilizer may be contained singly or in combination of two or more in any combination and ratio.

[0062] The content of the phenolic stabilizer is usually 0.001 part by mass or more, preferably 0.01 part by mass or more, and usually 1 part by mass or less, preferably 0.5 part by mass or less, based on 100 parts by mass of the polycarbonate resin (A). When the content of the phenolic stabilizer is less than the lower limit of the above range, the effect as a phenolic stabilizer may be insufficient. When the content of the phenolic stabilizer exceeds the upper limit of the above range, the effect may reach a plateau and it may become uneconomical.

[0063] [Release agent] The polycarbonate resin composition of the present invention preferably contains a release agent. As the release agent, known release agents usually used for resins can be used, and polyolefin-based compounds and fatty acid ester-based compounds are preferable.

[0064] Examples of the polyolefin-based compound include compounds selected from paraffin wax and polyethylene wax. Among them, those having a weight average molecular weight of 700 to 10,000, more preferably 900 to 8,000 are preferable.

[0065] Examples of the fatty acid ester-based compound include saturated or unsaturated monovalent or divalent aliphatic carboxylic acid esters, glycerin fatty acid esters, sorbitan fatty acid esters and other fatty acid esters and their partial saponified products. Among them, mono- or di-fatty acid esters composed of fatty acids having 11 to 28 carbon atoms, preferably 17 to 21 carbon atoms and alcohols are preferable.

[0066] Examples of the fatty acid include palmitic acid, stearic acid, caproic acid, capric acid, lauric acid, arachidic acid, behenic acid, lignoceric acid, cerotic acid, melissic acid, tetratetracontanoic acid, montanic acid, adipic acid, azelaic acid, etc. The fatty acid may be alicyclic. Examples of the alcohol include saturated or unsaturated monohydric or polyhydric alcohols. These alcohols may have substituents such as fluorine atoms and aryl groups. Among these, monohydric or polyhydric saturated alcohols having 30 or less carbon atoms are preferable, and aliphatic saturated monohydric or polyhydric alcohols having 30 or less carbon atoms are more preferable. Here, the aliphatic includes alicyclic compounds. Specific examples of such alcohols include octanol, decanol, dodecanol, stearyl alcohol, behenyl alcohol, ethylene glycol, diethylene glycol, glycerin, pentaerythritol, 2,2-dihydroxyperfluoropropanol, neopentylene glycol, ditrimethylolpropane, dipentaerythritol, etc. The above ester compound may contain aliphatic carboxylic acid and / or alcohol as impurities, and may be a mixture of a plurality of compounds.

[0067] Specific examples of the fatty acid ester compound include glycerin monostearate, glycerin monobehenate, glycerin dibehenate, glycerin-12-hydroxymonostearate, sorbitan monobehenate, pentaerythritol monostearate, pentaerythritol distearate, stearyl stearate, ethylene glycol montanate ester, etc.

[0068] The content of the release agent is preferably 0.1 to 3 parts by mass, more preferably 0.2 to 2.5 parts by mass, and still more preferably 0.25 to 2 parts by mass with respect to 100 parts by mass of the polycarbonate resin (A). If it is less than 0.1 part by mass, the surface property is likely to deteriorate due to poor release during melt molding. On the other hand, if it exceeds 3 parts by mass, the kneading workability of the resin composition is likely to deteriorate, and cloudiness is likely to occur on the surface of the molded body.

[0069] [Manufacture of Resin Composition] There is no limitation on the method for manufacturing the polycarbonate resin composition of the present invention, and known methods for manufacturing polycarbonate resin compositions can be widely adopted. The polycarbonate resin (A), styrene-acrylonitrile copolymer (C), and other components that are blended as necessary are premixed using various mixers such as a tumbler or Henschel mixer, and then melt-kneaded using a mixer such as a Banbury mixer, roll, Brabender, single-screw kneading extruder, twin-screw kneading extruder, or kneader.

[0070] The polycarbonate resin composition of the present invention can be used to manufacture various molded articles by molding pellets obtained by pelletizing the above-described resin composition using various molding methods. Alternatively, the resin melt-kneaded by an extruder can be directly molded into a molded article without passing through pellets.

[0071] The polycarbonate resin composition of the present invention is excellent in transparency, and its haze is preferably 5% or less, more preferably 4.5% or less, still more preferably 4.2% or less, and particularly preferably 4% or less for a 1-mm-thick molded article formed from the resin composition. The specific method for measuring the haze value is as described in the examples.

[0072] The polycarbonate resin composition of the present invention is excellent in transparency and has extremely low birefringence, and there are no problems with fluidity during molding and mold contamination. Therefore, as its applications, optical molded articles, specifically, various lenses, for example, lenses for various cameras, telescopes, microscopes, projectors, optical measuring devices, etc., various optical discs, home TVs, computer displays, in-vehicle display devices such as car navigation systems and car audio systems, display device panel members and films used in smartphones, head-mounted displays, barcode readers, scanners, etc. are preferably mentioned. In particular, it can be suitably used as a panel member for display devices used in various portable terminals such as smartphones, tablet computers, car navigation systems and car audio systems, portable game machines, digital cameras, etc., and particularly as a front member of a display device.

Examples

[0073] Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not construed as being limited to the following examples.

[0074] The raw materials used in the following examples and comparative examples are as shown in Table 1 below.

Table 1

[0075] (Examples 1 to 7, Comparative Examples 1 to 7) [Manufacture of Resin Composition Pellets] Each raw material described in Table 1 was blended at the ratios (parts by mass) shown in Table 2, mixed in a tumbler for 20 minutes, and then kneaded at a cylinder temperature of 260 °C and a screw rotation speed of 80 rpm using a single-screw extruder with a vent (manufactured by Tanabe Plastics Co., Ltd., "VS50-34V") having a screw diameter of 50 mm, and the extruded strands were cut to produce pellets. The obtained pellets were dried at 90 °C for 5 hours, and then injection molding was performed at a cylinder temperature of 280 °C and a mold temperature of 80 °C using an injection molding machine (manufactured by Sumitomo Heavy Industries, Ltd., "SE50DUZ") to prepare two-stage plate-shaped test pieces with dimensions of 111 mm × 36 mm and thicknesses of 1 mm and 3 mm. The following evaluations were performed on the obtained test pieces, and the results are shown in Table 2.

[0076] [Haze (unit: %)] Regarding the 1-mm-thick portion of the two-stage plate-shaped test piece obtained above, using a spectral haze meter ("SH7000" manufactured by Nippon Denshoku Industries Co., Ltd.), the haze (unit: %) was measured based on JIS K7375.

[0077] [Birefringence (unit: nm)] Regarding the 1-mm-thick portion of the two-stage plate-shaped test piece obtained above, using measurement wavelengths of 525 nm, 543 nm, and 575 nm, the birefringence (unit: nm) was measured with a wide-range two-dimensional birefringence evaluation system ("WPA-200" manufactured by Photonic Lattice). The above evaluation results are shown in Table 2 below.

[0078]

Table 2

Industrial Applicability

[0079] The polycarbonate resin composition of the present invention is excellent in transparency and has extremely low birefringence, so it can be suitably used as various high-performance optical molded articles.

Claims

1. A polycarbonate resin composition comprising 5 to 45 parts by mass of a styrene resin (B) having a refractive index higher than that of the polycarbonate resin (A) and 5 to 45 parts by mass of a styrene-acrylonitrile copolymer (C) having a refractive index lower than that of the polycarbonate resin (A) per 100 parts by mass of the polycarbonate resin (A), wherein the styrene resin (B) is a styrene-maleic anhydride copolymer.

2. The polycarbonate resin composition according to claim 1, wherein the polycarbonate resin (A) comprises a polycarbonate resin having a structural unit represented by the following general formula (1). 【Chemical Formula 1】 (In the general formula (1), R １ is a methyl group, R ２ and R ３ each independently represent a hydrogen atom or a methyl group, X represents, 【Chemical Formula 2】 any one of, R ４ and R ５ each independently represent a hydrogen atom or a methyl group, and Z represents a group that forms an alicyclic hydrocarbon having 6 to 12 carbon atoms which may have a substituent and is bonded to a carbon atom C.)

3. The polycarbonate resin composition according to claim 1 or 2, wherein the haze of a 1 mm thick molded article formed from the resin composition is 5% or less.

4. The polycarbonate resin composition according to any one of claims 1 to 3, wherein birefringence is reduced.

5. A molded article comprising the polycarbonate resin composition according to any one of claims 1 to 4.

6. The molded article according to claim 5, which is an optical molded article.

7. The molded article according to claim 5 or 6, which is a front member of a display panel.

Images