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 10-90 pts.mass of a styrene-acrylonitrile copolymer (B) based on 100 pts.mass of a polycarbonate resin (A). The amount of a styrene-derived unit in the styrene-acrylonitrile copolymer (B) is 75 mass% or more.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 resins as optical members, 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 the image quality and signal reading performance, so a transparent resin with a 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, when the birefringence is large, phase difference unevenness occurs, causing an iridescent pattern, or when viewing the screen through polarized sunglasses, the iridescent pattern becomes even more severe and unviewable, etc., there are problems such as a significant decrease in visibility and design quality (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, and 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 are 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 obtained by blending a polycarbonate resin (A) with a styrene resin (B) having an α,β-unsaturated dicarboxylic anhydride or a derivative thereof as a copolymer component, specifically a styrene-maleic anhydride copolymer (SMA resin), 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 into 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 circumstances, 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 has found that a styrene-acrylonitrile copolymer (AS resin) has negative birefringence, and among them, an AS resin having a large amount of styrene exhibits negative birefringence and also has a high refractive index, so that the refractive index becomes equal to that of the polycarbonate resin. It has been found that a polycarbonate resin composition containing this can solve the above problems. The present invention relates to the following polycarbonate resin composition and molded article.

[0009] 1. A polycarbonate resin composition characterized in that it contains 10 to 90 parts by mass of a styrene-acrylonitrile copolymer (B) with respect to 100 parts by mass of a polycarbonate resin (A), and the amount of units derived from styrene in the styrene-acrylonitrile copolymer (B) is 75% by mass or more. 2. The polycarbonate resin composition according to 1 above, wherein the polycarbonate resin (A) contains a polycarbonate resin having a structural unit represented by the following general formula (1). [Chemical formula] (In general formula (1), R 1 is a methyl group, R 2 and R 3each independently represents a hydrogen atom or a methyl group, and X represents [Chemical formula] any one of, R 4 and R 5 each independently represents 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.)

[0010] 3. The polycarbonate resin composition according to 1 or 2 above, wherein the haze of a 1 mm thick molded article formed from the resin composition is 10% or less. 4. The polycarbonate resin composition according to any one of 1 to 3 above, wherein the birefringence is reduced. 5. A molded article comprising the polycarbonate resin composition according to any one of 1 to 4 above. 6. The molded article according to 5 above, which is an optical molded article. 7. The molded article according to 5 or 6 above, which is a front member of a display device. [Advantages of the Invention]

[0011] The polycarbonate resin composition of the present invention has low birefringence, high transparency, and can achieve a low haze value. The styrene-acrylonitrile copolymer (B) contained in the polycarbonate resin composition of the present invention has a large amount of units derived from styrene of 75% by mass or more. Therefore, due to the large amount of benzene in the side chain of the copolymer, it has a high negative birefringence. Also, when the amount of units derived from styrene is large, the refractive index also increases. By reducing the amount of acrylonitrile having a functional group to 25% by mass or less, the haze can be reduced. As a result of these, while sufficiently canceling out the positive birefringence of the polycarbonate resin (A), the refractive index becomes comparable to that of the polycarbonate resin (A), and both transparency and low birefringence can be achieved at a high level simultaneously. [Modes 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 this 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 10 to 90 parts by mass of a styrene-acrylonitrile copolymer (B) with respect to 100 parts by mass of a polycarbonate resin (A), and the amount of units derived from styrene in the styrene-acrylonitrile copolymer (B) is 75% by mass or more.

[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 obtained by conventional methods such as the phosgene method (interfacial polymerization method) and the melting method (transesterification method).

[0016] Typical examples of the aromatic dihydroxy compound include 2,2-bis(4-hydroxyphenyl)propane (i.e., 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 terms of being likely to have the same refractive index level as the styrene-acrylonitrile copolymer (B). [Chemical formula] (In the general formula (1), R 1 is a methyl group, R2 and R 3 each independently represents a hydrogen atom or a methyl group, and X represents [Chemical formula] any one of, and R 4 and R 5 each independently represents 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, and R 2 and R 3 each independently represents a hydrogen atom or a methyl group, but R 2 and R 3 are particularly preferably hydrogen atoms.

[0019] Also, X is [Chemical formula] In the case of, it is preferable that both R 4 and R 5 are an isopropylidene group which is a methyl group, and when X is [Chemical formula] in the case of, Z is bonded to a carbon atom C that is bonded to two phenyl groups in the above general formula (1) 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, an ethyl substituent, etc. among these. Among these, a cyclohexylidene group, a methyl-substituted product of the cyclohexylidene group (preferably a 3,3,5-trimethyl-substituted product), and a cyclododecylidene group are preferable.

[0020] Preferable specific examples of the polycarbonate resin (A1) represented by the above general formula (1) include the following (a) to (b) polycarbonate resins. (a) Those having a 2,2-bis(3-methyl-4-hydroxyphenyl)propane structural unit, i.e., 1 where R 2 and R 3 are hydrogen atoms, and X is an isopropylidene group, and those having a structural unit derived from bisphenol C. (b) A 2,2-bis(3-methyl-4-hydroxyphenyl)cyclododecane structural unit, i.e., R 1 is a methyl group, R 2 and R 3 are hydrogen atoms, and those having a structural unit where X is a cyclododecylidene group. (c) A 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane structural unit, i.e., R 1 is a methyl group, R 2 and R 3 are methyl groups, and those having a structural unit where X is an isopropylidene group. (b) A 2,2-bis(3-methyl-4-hydroxyphenyl)cyclohexane structural unit, i.e., R 1 is a methyl group, R 2 and R 3 are hydrogen atoms, and those having a structural unit where 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 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, and 2,2-bis(3-methyl-4-hydroxyphenyl)cyclohexane, respectively, as dihydroxy compounds.

[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 the other carbonate units include the following aromatic dihydroxy compounds. 2,2-bis(4-hydroxyphenyl)propane, 2,2-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, 1,1-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, and the like.

[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] One type of polycarbonate resin (A1) may be used, or two or more types may be used in combination at any combination and any ratio.

[0025] When using the above 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 starting from 2,2-bis(4-hydroxyphenyl)propane (i.e., bisphenol A) is particularly preferable.

[0026] When other polycarbonate resin (A2) is also contained as the polycarbonate resin (A), its content is preferably less than 50% by mass, more preferably 40% by mass or less, still more preferably 30% by mass or less, particularly preferably 25% by mass or less, 20% by mass or less, and especially 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 above general formula (1), it is treated as the polycarbonate resin (A1).

[0027] 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.

[0028] The viscosity average molecular weight Mv of the polycarbonate resin (A) is obtained 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 is the value calculated from the Schnell viscosity formula, η = 1.23×10 -4 Mv 0.83 The intrinsic viscosity [η] means the value calculated by measuring the specific viscosity [η sp at each solution concentration [C] (g / dl) according to the following formula.

Equation

[0029] [Styrene-acrylonitrile copolymer (B)] The polycarbonate resin composition of the present invention contains a styrene-acrylonitrile copolymer (B) in which the amount of units derived from styrene is 75% by mass or more. The styrene-acrylonitrile copolymer (B) is a copolymer of acrylonitrile and a styrene-based monomer.

[0030] Examples of the styrene-based monomer constituting the styrene-acrylonitrile copolymer (B) 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.

[0031] The styrene-acrylonitrile copolymer (B) may be a copolymer with other copolymerizable monomers in addition to acrylonitrile and styrene-based monomers. Examples of other copolymerizable monomers in addition to styrene-based monomers and acrylonitrile include (meth)acrylate-based monomers, maleimide-based 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. Among these, (meth)acrylate-based monomers are preferably mentioned. For example, methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, butyl (meth)acrylate, amyl (meth)acrylate, hexyl (meth)acrylate, octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, cyclohexyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, phenyl (meth)acrylate, benzyl (meth)acrylate, etc. can be mentioned, and particularly methyl methacrylate can be mentioned. Note that the notation "(meth)acrylate" indicates that it includes both methacrylate and acrylate, and the notation "(meth)acrylic acid ester" indicates that it includes both methacrylic acid ester and acrylic acid ester.

[0032] In the styrene-acrylonitrile copolymer (B), the amount of units derived from styrene is 75% by mass or more, and the amount of units derived from acrylonitrile monomer is 25% by mass or less, based on 100% by mass in total. By setting the amount of units derived from styrene in the copolymer (B) to 75% by mass or more, it becomes possible to achieve high transparency, specifically, excellent transparency with a haze of preferably 10% or less, more preferably 7% or less, particularly 5% or less at a thickness of 1 mm, and a low birefringence value (retardation).

[0033] The amount of units derived from styrene is preferably 77% by mass or more, 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 23% by mass or less, 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 (B) is a copolymer and does not contain a styrene homopolymer. The transparency of a styrene homopolymer (polystyrene) is poor, and it is difficult to achieve the haze as described above.

[0034] When the styrene-acrylonitrile copolymer (B) is a copolymer with other copolymerizable monomers other than acrylonitrile and styrene-based monomers, the amount of units derived from other copolymerizable monomers other than styrene-based monomers and acrylonitrile is preferably 20% by mass or less, more preferably 10% by mass or less, still more preferably 5% by mass or less, particularly preferably 3% by mass or less, and especially preferably 2% by mass or less, and particularly preferably 1% by mass or less, based on 100% by mass of the copolymer (B).

[0035] The styrene-acrylonitrile copolymer (B) is preferably an acrylonitrile-styrene resin composed of acrylonitrile and styrene, which is usually also referred to as AS resin.

[0036] There is no limitation on the method for producing the styrene-acrylonitrile copolymer (B), and known methods can be adopted. For example, methods such as bulk polymerization, emulsion polymerization, solution polymerization, and suspension polymerization are used.

[0037] The content of the styrene-acrylonitrile copolymer (B) is 10 to 90 parts by mass with respect to 100 parts by mass of the polycarbonate resin (A). By being in such a range, transparency (haze) and low birefringence can be achieved at a high level simultaneously. If the content is less than 10 parts by mass, the birefringence improvement effect 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 (B) is preferably 12 parts by mass or more, more preferably 13 parts by mass or more, preferably 80 parts by mass or less, more preferably 70 parts by mass or less, still more preferably 60 parts by mass or less, and particularly preferably 50 parts by mass or less.

[0038] [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.

[0039] [Ultraviolet Absorber] It is also preferable that the polycarbonate resin composition of the present invention 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 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.

[0040] 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-benzotriazole-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-benzotriazole-2-yl)phenol] are preferred, and particularly 2-(2'-hydroxy-5'-tert-octylphenyl)benzotriazole is preferred.

[0041] 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.

[0042] 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'-ethyloxalanilic 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.

[0043] When the ultraviolet absorber is contained, 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 of the above range, the effect of improving weather resistance may be insufficient. When the content of the ultraviolet absorber exceeds the upper limit 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.

[0044] [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.

[0045] 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.

[0046] 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, didecyldiphenyl phosphite, tridecyl phosphite, trilauryl phosphite, tristearyl phosphite, 2,2-methylenebis(4,6-di-tert-butylphenyl) octyl phosphite, and the like.

[0047] 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.

[0048] The phosphorus-based stabilizer may be contained singly, or may be contained in two or more kinds in any combination and ratio.

[0049] 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.

[0050] 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.

[0051] 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 may be contained in two or more kinds in any combination and ratio.

[0052] 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 may become uneconomical.

[0053] [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.

[0054] 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, and more preferably 900 to 8,000 are preferable.

[0055] 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.

[0056] 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 and the like. 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 and the like. The above ester compound may contain aliphatic carboxylic acid and / or alcohol as impurities, and may be a mixture of a plurality of compounds.

[0057] 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 and the like.

[0058] 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.

[0059] [Manufacture of Resin Composition] There is no limitation on the manufacturing method of the polycarbonate resin composition of the present invention, and the known manufacturing methods of polycarbonate resin compositions can be widely adopted. The polycarbonate resin (A), styrene-acrylonitrile copolymer (B), and other components blended as required are premixed using various mixers such as a tumbler and a Henschel mixer, and then melt-kneaded using a mixer such as a Banbury mixer, a roll, a Brabender, a single-screw kneading extruder, a twin-screw kneading extruder, or a kneader.

[0060] 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. Also, without passing through the pellets, the resin melt-kneaded by an extruder can be directly molded into a molded article.

[0061] The polycarbonate resin composition of the present invention is excellent in transparency, and as its haze, the haze of a 1 mm-thick molded article formed from the resin composition is preferably 10% or less, more preferably 8% or less, still more preferably 7% or less, particularly preferably 6% or less, and most preferably 5% or less. The specific method for measuring the haze value is as described in the examples.

[0062] The polycarbonate resin composition of the present invention is excellent in transparency and has extremely low birefringence, and also has no problems with fluidity during molding and mold contamination. Therefore, its applications include optical molded articles, specifically, various lenses, for example, lenses for various cameras, telescopes, microscopes, projectors, optical measuring devices, etc., various optical discs, home televisions, 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. In particular, it is preferably 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 in particular, it can be suitably used as a front member of a display device.

Examples

[0063] 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.

[0064] The raw materials used in the following examples and comparative examples are as shown in Table 1 below.

Table 1

[0065] (Examples 1 to 7, Comparative Examples 1 to 5) [Production of Resin Composition Pellets] Each raw material described in Table 1 was blended in the proportions (parts by mass) shown in Table 2, mixed for 20 minutes in a tumbler, 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. 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 having dimensions of 111 mm × 36 mm and thicknesses of 1 mm and 3 mm. For the obtained test pieces, the following evaluations were carried out, and the results are shown in Table 2.

[0066] [Haze (unit: %)] For the 1-mm-thick part of the two-stage plate-shaped test piece obtained above, using a spectral haze meter ("SH7000" manufactured by Nippon Denshoku Industries Co., Ltd.), based on JIS K7375, the haze (unit: %) was measured.

[0067] [Birefringence (unit: nm)] For the 1-mm-thick part 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.

[0068] [Table 2] [Industrial Applicability]

[0069] 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 containing 13 to 90 parts by mass of a styrene-acrylonitrile copolymer (B) with respect to 100 parts by mass of a polycarbonate resin (A), wherein the amount of units derived from styrene in the styrene-acrylonitrile copolymer (B) is 78% by mass or more and less than 85% by mass, The polycarbonate resin composition is characterized in that the haze of a 1 mm thick molded body formed from the polycarbonate resin composition is 10% or less.

2. The polycarbonate resin composition according to claim 1, wherein the haze of a 1 mm thick molded body formed from the polycarbonate resin composition is 7% or less.

3. The polycarbonate resin composition according to claim 1 or 2, wherein the polycarbonate resin (A) contains a polycarbonate resin having a structural unit represented by the following general formula (1). 【Chemical Formula 1】 (In the 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 2】 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.)

4. The polycarbonate resin composition according to claim 3, wherein the polycarbonate resin (A) contains the polycarbonate resin (A1) represented by the general formula (1) and another polycarbonate resin (A2) other than the polycarbonate resin (A1), and the content of the other polycarbonate resin (A2) is less than 50% by mass in 100% by mass of the polycarbonate resin (A).

5. The polycarbonate resin composition according to any one of claims 1 to 4, having reduced birefringence.

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

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

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

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