JPH0780978B2 - Optical molding material - Google Patents

Description

TECHNICAL FIELD The present invention relates to an optical molding material composed of a copolymer composed of an aromatic polycarbonate and a styrene polymer. More specifically, in the presence of an aromatic polycarbonate having an unsaturated group at the molecular end or side chain, maleic anhydride or maleimide or a derivative thereof and an aromatic polycarbonate obtained by copolymerizing a styrene monomer and a styrene polymer The present invention relates to an optical molding material which is a copolymer, in which an aromatic polycarbonate portion and a styrene-based polymer portion have a specific weight ratio, and dispersed phase particles are particles having a particle size of 0.5 μm or less. The optical molding material according to the present invention is particularly excellent in optical uniformity because it has a reduced optical strain and is a dispersed phase composed of very fine particles, and has sufficient heat resistance. It is suitable for use in lenses, optical cards, optical tapes, etc.

[Conventional technology and its problems]

Conventionally, as a material for an optical transparent molded product, an acrylic resin has been known as a material for an optical transparent molded product because of its characteristics such as transparency, fluidity and small birefringence. (JP Sho
56-131654, etc.), but acrylic resin has a heat resistance of about 7
It is low at 0 ° C, has low impact resistance, and has the drawback that it tends to warp due to moisture. On the other hand, viscosity average molecular weight 15,000
It is known to use up to 18,000 polycarbonate resins as molding materials for disks, lenses, etc.
58-180553), however, has a drawback such as insufficient fluidity and large birefringence, which is important in discs and lenses, and its use is limited.

For the above reasons, methods for maintaining the excellent characteristics of aromatic polycarbonate resins and eliminating optical distortion have been investigated.

One of the important problems in practical application of optical materials, mainly optical disk materials, is the problem of reducing the noise level of the substrate itself. It has been clarified that this noise level exists in birefringence including obliquely incident light (for example, Optics, vol.15.No.5 (October 1986) p.441-421, Optical Memory Symposium '86). Proceedings p.33-38).

That is, the reduction of the birefringence of the vertically incident light does not necessarily correlate with the change of the birefringence of the obliquely incident light, and this difference is remarkable especially in the case of polycarbonate resin, and the reduction of the birefringence in the wide-angle range of the light is reduced. Is important.

As an attempt to reduce the birefringence, various methods of forming a composition of an aromatic polycarbonate and another resin such as polystyrene have been proposed. (For example, JP-A-61-19630,
61-19656, 62-18466, 62-20524, 61-108
No. 617, and functional materials March 1987 p21-29).

However, all of these proposals are intended to reduce the birefringence of vertically incident light, and the birefringence of obliquely incident light described above is not considered without any reference, and the birefringence in the wide-angle range of light is not considered. Noise level (optical distortion of obliquely incident light)
Is not satisfactory from the practical point of view of reduction. Further, more importantly, in a mere mixed composition with another resin, or in a copolymer composition system containing a large amount of a homopolymer even in the case of a copolymer, dispersed phase particles of components in the composition Of the dispersed phase particles becomes coarser as a result, for example, the dispersed phase particles become particles of about 3 μm, which is larger than 0.5 μm, and even if the birefringence in the measurement is reduced to 0, the dispersed phase particles are dispersed in the micron size region. Due to the refractive index difference at the particle interface, it becomes optically non-uniform such as a scattering source,
It may cause noise. On the other hand, in the case of a resin composition of polycarbonate and polystyrene, heat resistance is lowered, which is not preferable.

As described above, the modified polycarbonate obtained by the conventional method is not yet satisfactory in terms of elimination of birefringence of obliquely incident light, optical uniformity and heat resistance.

[Means for Solving the Problems]

The present inventors have conducted extensive studies on a method for improving the above-mentioned drawbacks, and as a result, in the presence of an aromatic polycarbonate having an unsaturated group at a molecular end or a side chain, maleic anhydride or maleimide or a derivative thereof and a styrenic monomer. A copolymer comprising an aromatic polycarbonate and a styrene-based polymer, wherein the aromatic polycarbonate portion and the styrene-based polymer portion of the copolymer have a specific weight ratio, and the dispersion thereof is It has been found that a copolymer having phase particles of 0.5 μm or less has excellent birefringence and heat resistance and is suitable as an optical molding material.

That is, the present invention, in the presence of an aromatic polycarbonate having an unsaturated group at the molecular end or side chain, maleic anhydride or maleimide or an aromatic polycarbonate and a styrene-based polymer obtained by copolymerizing these derivative styrene-based monomers. The weight ratio of the aromatic polycarbonate portion and the styrene-based polymer portion in the copolymer is 30:70 to 90:10, and the maleic anhydride or maleimide or these of the styrene-based polymer is The present invention relates to a transparent optical molding material in which the copolymerization ratio of the derivative and the styrene-based monomer is 1:99 to 50:50, and the dispersed phase particles of the copolymer are particles of 0.5 μm or less.

The configuration of the present invention will be described below.

The copolymer comprising an aromatic polycarbonate and a styrene-based polymer in the present invention, in the presence of an aromatic polycarbonate having an unsaturated group at the molecular end or side chain,
A copolymer of maleic anhydride or maleimide or a derivative thereof and a styrene-based monomer,
As described above, the weight ratio of the aromatic polycarbonate portion and the styrene-based polymer portion is specified, the copolymerization ratio of maleic anhydride or maleimide or a derivative thereof and a styrene-based monomer in the styrene-based polymer is specified, and dispersed phase particles Is composed of submicron particles of 0.5 μm or less.

First, the weight ratio of the aromatic polycarbonate portion and the styrenic polymer portion is in the range of 30:70 to 90:10, preferably
It is selected in the range of 40:60 to 70:30. This weight ratio mainly correlates with optical distortion in a wide angle range of light, and outside this range, the difference in birefringence between vertically incident light and obliquely incident light cannot be reduced.

Furthermore, the polystyrene reduced weight average molecular weight (= PCMw) of the aromatic polycarbonate part is 10,000 ≦ PCMw ≦ 80,000
, Preferably in the range of 25,000 ≦ PCMw ≦ 65,000.

On the other hand, the polystyrene equivalent weight average molecular weight (= PSMw) of the styrene-based polymer portion is selected from the range of 20,000 ≦ PSMw ≦ 250,000, preferably 30,000 ≦ PCMw ≦ 120,000.

In the present invention, the above weight ratio, the dispersed phase particles 0.5μ
When the particles are submicron particles of m or less, and further, the molecular weight and the like are satisfied as a whole, they are good optical molding materials.

When these conditions are satisfied and they are preferably combined, the birefringence becomes within the range of 10 nm or less together with the vertically incident light and the obliquely incident light, and the injection molding condition, for example, the molding temperature is changed as shown in Examples described later. Even when it is made to be a material, the absolute value of birefringence changes only within a range of 30 nm or less.

In the present invention, the molecular weight itself does not directly affect the birefringence, but it affects the mechanical properties of the molded product, it affects the molding processability, PCMw, PSMw mechanical properties as a molding material is less than the lower limit. Is inferior, and if it exceeds the upper limit, there is a problem in terms of molding processability, which is not preferable.

The method for producing a copolymer comprising an aromatic polycarbonate and a styrene-based polymer as the optical molding material of the present invention is an aromatic polycarbonate having an average of at least one unsaturated group per molecule at the molecular end or side chain. It can be produced by a method of copolymerizing maleic anhydride or maleimide or a derivative thereof with a styrene-based monomer in the presence of

The method for producing an aromatic polycarbonate having an average of at least one unsaturated group per molecule at the molecular end or side chain used in the present invention is a monofunctional compound having an unsaturated double bond as a chain transfer agent or an end terminator. Sex compounds,
Alternatively, except that these are used in combination with a conventional end-capping agent, the same method as a conventional aromatic polycarbonate production method, that is, an interfacial polymerization method, a pyridine method, a solution method such as a chloroformate method, is used. Viscosity average molecular weight 2,000-1
00,000, preferably 5,000-50,000, especially 6,000-30,000
belongs to.

The preferred dihydric phenol compound used in the method for producing an aromatic polycarbonate having an unsaturated group at the molecular end or side chain of the present invention is specifically bis (4
-Hydroxyphenyl) methane, 1,1-bis (4-hydroxyphenyl) ethane, 1,1-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis (4-hydroxyphenyl) pentane, 2,2-bis (4-hydroxyphenyl) isopentane, 2,2-bis (4-hydroxyphenyl) hexane), 2, 2-bis (4-hydroxyphenyl) isohexane, bis (4-hydroxyphenyl) phenylmethane, bis (4-hydroxyphenyl) diphenylmethane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2 -Bis (4-hydroxy-3,5-dimethylphenyl) propane, 1,1-bis (4-hydroxyphenyl) cyclohexane, dihydroxydiphenyl Sulfone, dihydroxydiphenyl sulfide, bisphenols such as dihydroxy diphenyl ether, and hydroquinone, resorcinol, o- methyl resorcinol,
Examples are divalent phenols such as o-cumylresorcin. Of these, the use of 2,2-bis (4-hydroxyphenyl) propane is particularly preferable.

Further, as the monofunctional compound having an unsaturated double bond for introducing an unsaturated group into the molecular terminal or the side chain, acrylic acid chloride, methacrylic acid chloride, sorbic acid chloride, allyl alcohol chloroformate, iso Acid chlorides and chloroformates such as propenylphenol chloroformate; phenols having unsaturated groups such as isopropenylphenol, hydroxystyrene, hydroxyphenylmaleimide, hydroxybenzoic acid allyl ester, and hydroxybenzoic acid methylallyl ester. To be

These compounds may be used in combination with a conventional end-stopping agent, and the amount of the dihydric phenol compound may be 1
It is used in the range of -25 mol, preferably 1.5-10 mol.

Polycarbonate having an unsaturated group at the molecular end or side chain in the present invention is produced as described above,
Further, if necessary, a branching agent may be used in combination in the range of 0.01 to 3.0 mol%, particularly 0.1 to 1.0 mol% with respect to the above dihydric phenol compound to give a branched polycarbonate.

Examples of such a branching agent include phloroglysin and 2,6-
Dimethyl-2,4,6-tri (4-hydroxyphenyl) heptene-3,4,5-dimethyl-2,4,6-tri (4-hydroxyphenyl) heptene-2,1,3,5-tri ( 2-hydroxyphenyl) benzole, 1,1,1-tri (4-hydroxyphenyl) ethane, 2,6-bis (2-hydroxy-5-methylbenzyl) -4-methylphenol, α,
α ′, α ″ -tri (4-hydroxyphenyl) -1,3,5
-A polyhydroxy compound exemplified by triisopropylbenzene, and 3,3-bis (4-hydroxyaryl) oxindole (= isatin bisphenol), 5-chloroisatin bisphenol, 5,7-dichloroisatin bisphenol , 5-bromoisatin bisphenol and the like.

Next, in the present invention, maleic anhydride or maleimide or a derivative thereof and a styrenic monomer which are copolymerized in the presence of an aromatic polycarbonate having an unsaturated group at a molecular end or a side chain will be described.

First, the styrene-based monomer in the present invention is specifically styrene, o-methylstyrene, p-methylstyrene, α-methylstyrene, o-butylstyrene, p-butylstyrene, chlorostyrene, bromostyrene, 2, Four
-Dimethylstyrene and the like are exemplified.

In the present invention, maleic anhydride, maleimide, or a derivative thereof is used together with the styrene-based monomer. Specific examples of the maleic anhydride or maleimide or derivatives thereof include maleic anhydride, α-methylmaleic anhydride, maleimide, N-
Examples thereof include methylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-butylmaleimide, N-ethylmaleimide, N-benzylmaleimide, N-cyclohexylmaleimide and N-phenylmaleimide.
Of these compounds, use of maleic anhydride, N-cyclohexylmaleimide, N-phenylmaleimide is particularly preferable.

The copolymerization ratio of maleic anhydride or maleimide or a derivative component thereof and a styrenic monomer in a styrenic polymer obtained by copolymerizing the above monomers is 1:99 to 50:50, preferably 2 :. A range of 98 to 45:55 is preferable, and a range of 3:97 to 40:60 is particularly preferable. When the copolymerization ratio is less than 1:99, remarkable improvement in optical uniformity and heat resistance are not observed. On the other hand, the copolymerization ratio is 50: 5
If it exceeds 0, the optical uniformity and the moldability are deteriorated, which is not preferable.

In the present invention, in addition to the above-mentioned styrene-based monomer and maleic anhydride, maleimide or derivatives thereof, other vinyl-based monomers such as methyl methacrylate, ethyl methacrylate, butyl methacrylate, N-hexyl acrylate and butyl acrylate are also used. And acrylates such as cyclohexyl methacrylate; glycidyl methacrylate, acrylic acid, acrylamide, methacrylamide, N-methoxyacrylamide, acrylonitrile and the like can be used in combination.

In the present invention, maleic anhydride, maleimide or a derivative thereof in the presence of an aromatic polycarbonate having an unsaturated group at the molecular end or side chain is reacted with a styrene monomer to form a copolymer, and the molecular weight thereof is adjusted. Examples of the means include a method using a thermal polymerization temperature, a method using an initiator concentration, and a method using a molecular weight modifier.

Although these methods can be used in combination, the method using a molecular weight modifier is particularly suitable for the copolymerization reaction of the present invention.

An organic sulfur compound is used as the molecular weight modifier.
Preferred organic sulfur compounds are aliphatic or aromatic compounds having 1 to 30 carbon atoms, specifically, n-butyl mercaptan, isobutyl mercaptan, n-octyl mercaptan, n-dodecyl mercaptan, sec-butyl mercaptan, sec- Primary, secondary and tertiary mercaptans such as dodecyl mercaptan and tert-butyl mercaptan;
Examples thereof include aromatic mercaptans such as phenylmercaptan, thiocresol, and 4-tert-butylthiocresol; thioglycolic acid and its esters; and mercaptans having 3 to 18 carbon atoms such as ethylenethioglycol. Of these compounds, n-dodecyl mercaptan, tert-dodecyl mercaptan, and n-octyl mercaptan are most preferred.

These are used in an amount of 5% by weight based on the total amount of the aromatic polycarbonate having an unsaturated group at the molecular end or side chain used for the copolymerization reaction, maleic anhydride or maleimide or their derivatives, and the styrene-based monomer.
Below, it is preferably in the range of 0.0004 to 2% by weight. If it is used in an amount of more than 5% by weight, the degree of polymerization is lowered and mechanical properties are deteriorated, which is not preferable.

Examples of the polymerization initiator used in the present invention include di-tert-butyl peroxide, dinonyl peroxide, methyl ethyl ketone peroxide, di-tert.
-Butyl diperphthalate, lauroyl peroxide, di-tert-amyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide, benzoyl peroxide and other organic peroxides; 2,2-azobisisobutyronitrile Azo compounds such as 1,1-azobiscyclohexylcarbonitrile and 2-cyano-2-propylazoformamide. The amount of these used is generally in the range of 0 to 1% by weight.

〔Example〕

 The present invention will be specifically described below with reference to examples.

Incidentally, the viscosity average molecular weight, total light transmittance, haze value, etc. of Examples and the like.
The Vicat softening temperature and the phase dispersion (phase dispersed particles) were determined by the following methods.

(1) Viscosity average molecular weight-Measurement of solution viscosity Sample solution: 0.2 g / 100 ml methylene chloride solution Viscometer: Flow time (T ₀ ) of solvent only 72.36 seconds Capillary color improvement Ubbelohde viscometer Measurement temperature: 20 ° C ± 0.01 ℃ Flow time (T) of concentration 0.2g / 100ml by this measurement
To measure. From the above measurement, η _rel , η _ap , and [η] are calculated from the following formulas, and Mv is calculated from (Schenell's formula).

η _ap = T / T ₀ -1 (η _rel = T / T ₀ ) ...) η _ap : Specific viscosity T: Flow time of sample solution T ₀ : Flow time of solvent only η _ap / C = [η] + K ′ [Η] ² / C …… [η]: Ultimate (intrinsic) viscosity C: Concentration of sample solution K ′: Huggins constant (K ′ = 0.45) [η] = K _mm M ^α _v …… K _m : 1.23 × 10 ^-4 α: 0.83 (2) Styrene equivalent weight average molecular weight GPC measurement (3) Total light transmittance and cloudiness Sample: Molded product with a thickness of 3 mm Measuring device: Nippon Denshoku Industries Hazemeter / Model 1001 D
P (4) Vicat softening temperature JIS K 7206A method 1kg load (5) Phase dispersion (dispersed phase particles) Observation by electron microscope (6) Birefringence ・ Sample and equipment sample: 1.2mm thick, 130mm diameter molded article measurement Wavelength: 632.8nm Measuring device: manufactured by Mizojiri Optical Co., Ltd., automatic ellipsometer ・ Vertical incident light and oblique incident light refraction Vertical incident light birefringence (Re ⁰ ) Represents birefringence for light rays perpendicularly incident on the sample surface .

Birefringence of obliquely incident light (Re ^max30 ) Birefringence for a light ray forming an angle of 30 ° from a vertically incident light ray is called obliquely incident light birefringence (Re ³⁰ ), and all directions (0 to 0) in which the injection direction of a molded product is 0 ° the maximum value of Re ³⁰ in 360 °) is referred to as ^Re max30.

Reference Examples 1 to 4 Sodium hydroxide (22 kg) was dissolved in water (256 l), and 2,2-bis (4-hydroxyphenyl) propane (= BPA) (45.6 kg) and hydrosulfite (50 g) were dissolved while maintaining the temperature at 20 ° C.

150 l of methylene chloride (= MC) was added to this, and phosgene was blown in with stirring. After 30 minutes, 125 kg of MC containing 1.95 kg of p-isopropenylphenol was added, and 30 more of phosgene was added.
Blown for a minute. After the completion of blowing phosgene, the reaction solution was emulsified by vigorous stirring. After emulsification, 30 l of a 1% triethylamine MC solution was added, and stirring was continued for about 1 hour for polymerization.

The polymerization liquid is separated into an aqueous phase and an organic phase, and the organic phase is neutralized with phosphoric acid, and then repeatedly washed with water several times, and then dropped into methanol to precipitate the copolymer, which is then filtered and dried to obtain white. An aromatic polycarbonate having a powdery unsaturated group at its end was obtained.

Polystyrene equivalent weight average molecular weight of this powder (= PCMw)
Was 32,000, and the viscosity average molecular weight (= PCMv) was 16,000 from the viscosity measurement of the methylene chloride solution.

PCMw (PCMv) is 45,000 (20,000), 49,000 (2
2,000) and 54,000 (24,000) unsaturated group-terminated aromatic polycarbonates were obtained. These are PC-1, PC-2, PC-3, PC-4 in order of decreasing viscosity average molecular weight.
Called.

Reference Example 5 In the same manner as in Reference Example 1, except that acrylic acid chloride was used instead of p-isopropenylphenol, the aromatic group having an unsaturated group at the end having PCMw (PCMv) of 49,500 (22,000) according to Reference Example 1. A polycarbonate was obtained. (Hereinafter referred to as PC-5) Example 1 2.5 kg of PC-1 obtained in Reference Example 1, styrene monomer (hereinafter S
11 kg is placed in a pressure-resistant container, and after nitrogen substitution is performed, the temperature is raised to 120 ° C. with stirring, and 11 g of n-dodecyl mercaptan (hereinafter, referred to as NDS), maleic anhydride (hereinafter,
1) while adding a mixed solution of 154 g and St 1.5 kg.
Reacted for 00 minutes.

After the reaction was completed, the product was dissolved in MC and added to methanol for precipitation to obtain a copolymer composed of an aromatic polycarbonate and a styrene polymer. A copolymer composed of this aromatic polycarbonate and a styrene polymer (hereinafter referred to as G-1
Was analyzed by infrared spectroscopy. As a result, the weight ratio of the aromatic polycarbonate portion (hereinafter referred to as PC) to the styrene-based polymer portion (hereinafter referred to as SMA) was PC / SMA = 60.
It was 8 / 39.2. MA in SMA measured by titration method
And the copolymerization ratio of St was 9.3: 90.7.

The G-1 produced above was fed to a 20 mm vented extruder and pelletized at a cylinder temperature of 240-260 ° C. After drying the pellets at 110 ° C for 5 hours or more, injection molding was performed at the cylinder temperature and the mold temperature of 90 ° C shown in Table 1 to prepare a disc, and a disc was formed on a concentric circle of 42 mm from the disc center. Refraction and dispersed phase particles were measured.

Further, the above pellets were press-molded to obtain a molded product having a thickness of 3 mm, and after standing for 24 hours, the total light transmittance, haze value and Vicat softening temperature were measured. The measurement results are collectively shown in Table 1.

Examples 2 to 5 PC-2, PC-3, PC-4 obtained in Reference Examples 2, 3, 4 and 5 and
A copolymer composed of an aromatic polycarbonate and a styrene-based polymer was obtained in the same manner as in Example 1 except that PC-5 was used as a raw material (corresponding to PC-2 to PC-5, G-2 and G, respectively).
-3, G-4 and G-5). The test was performed in the same manner as in Example 1 except that G-2 to G-5 were used. The result is first
Shown in the table.

Example 6 In Example 1, PC-2 was used instead of PC-1, and ND
A copolymer of an aromatic polycarbonate and a styrene polymer (hereinafter referred to as G-6) was obtained in the same manner as in Example 1 except that S19g and MA330g were used. The same test as in Example 1 was conducted on G-6. The results are shown in Table 2.

Example 7 2.5 kg of PC-2 and St9.2 kg of PC-2 obtained in Reference Example 2 were placed in a pressure resistant vessel, and the atmosphere was replaced with nitrogen. Then, the temperature was raised to 120 ° C. with stirring to obtain NDS.
The reaction was carried out for 90 minutes while adding a mixed solution of 22 g, MA 667 g and St 4.2 kg.

After completion of the reaction, the product was treated in the same manner as in Example 1 to obtain a copolymer composed of an aromatic polycarbonate and a styrene polymer (hereinafter referred to as G-7). Example 1 for G-7
Tested as above. The results are shown in Table 2.

Example 8 2.5 kg of PC-2 and St9.2 kg obtained in Reference Example 2 were placed in a pressure resistant vessel, and the atmosphere was replaced with nitrogen. Then, the temperature was raised to 120 ° C. with stirring to obtain NDS.
The mixture was reacted for 90 minutes while adding a mixed solution of 25 g, MA833 g and St 4.2 kg.

After completion of the reaction, the product was treated in the same manner as in Example 1 to obtain a copolymer composed of an aromatic polycarbonate and a styrene polymer (hereinafter referred to as G-8). Example 1 for G-8
Tested as above. The results are shown in Table 2.

Example 9 A copolymer of an aromatic polycarbonate and a styrene polymer (hereinafter referred to as G-9) was obtained in the same manner as in Example 8 except that NDS was changed to 28 g and MA1111 g. G-9 was tested as in Example 1. The results are shown in Table 2.

Examples 10 and 11 Example 1 except that MA was changed to 314 g of N-phenylmaleimide (hereinafter referred to as MI-1) or 325 g of N-cyclohexylmaleimide (hereinafter referred to as MI-2) in Example 1 A copolymer composed of an aromatic polycarbonate and a styrene-based polymer (hereinafter, G-
10, referred to as G-11). G-10 and G-11 were tested in the same manner as in Example 1. The results are shown in Table 3.

Comparative Example 1 Aromatic polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Inc.,
Trade name: Iupilon H-4000 or less, referred to as PCH4) was used and a test piece was prepared and tested in the same manner as in Example 1.
The results are shown in Table 3.

Comparative Example 2 A copolymer of aromatic polycarbonate and polystyrene (hereinafter, referred to as GC-1) was obtained in the same manner as in Example 1 except that MA was not used, and the same test was carried out. It was The results are shown in Table 3.

[Operation and Effect of the Invention] The copolymer comprising the aromatic polycarbonate and the styrenic polymer of the present invention, as is clear from the above description, the birefringence is significantly reduced, and the heat resistance is not impaired. It has excellent optical uniformity and can be suitably used as an optical molding material used for optical disks, optical lenses, optical cards, optical tapes and the like.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideaki Watanabe 6-1, 1-1 Shinjuku, Katsushika-ku, Tokyo Mitsubishi Gas Chemical Co., Ltd. Headquarters Research Center Akira Fujii

Claims (1)

[Claims] 1. From an aromatic polycarbonate obtained by copolymerizing maleic anhydride or maleimide or a derivative thereof with a styrene monomer in the presence of an aromatic polycarbonate having an unsaturated group at a molecular end or a side chain, and a styrene polymer. Wherein the weight ratio of the aromatic polycarbonate portion to the styrene polymer portion in the copolymer is 30:70 to 90:10, and the maleic anhydride or maleimide or the derivative thereof in the styrene polymer is A transparent optical molding material in which the copolymerization ratio of styrene to a styrene monomer is 1:99 to 50:50, and the dispersed phase particles of the copolymer are particles of 0.5 μm or less.