JPS63305114A - Molding material for optics - Google Patents

Abstract

PURPOSE:To provide a clear molding material for optics decreased in optical distortion and excellent in micro phase dispersion, comprising a resin composition containing as a main component a graft copolymer with a styrene compound which comprises an aromatic polycarbonate as backbone polymer. CONSTITUTION:A molding material for optics comprises a graft copolymer with a styrene compound having a weight-average molecular weight of 25,000-80,000 in terms of polystyrene and comprising an aromatic polycarbonate as backbone polymer and is made of a resin composition which comprises as a main component a graft polycarbonate with ratios represented by (1) and (2) described below, and which is clear and has a micro phase dispersion of 0.5mum or below. (1): the ratio of the molecular weights of respective parts is 0.2<=PCMW/PSMW<=4 (wherein PCMW is the weight-average molecular weight of the constituent units of the aromatic polycarbonate in terms of polystyrene and PSMW is a weight-average molecular weight of the constituent units of the styrene compound polymer. (2): the ratio of respective constituent units is 30/70<=PC/PS<=90/10. In the formula, PC is the weight of the constituent unit of the aromatic polycarbonate, and PS is the weight of the constituent unit of the styrene compound polymer.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention has an aromatic polycarbonate as a main component, and the aromatic polycarbonate structural unit and the polystyrene compound structural unit have a specific molecular weight ratio and weight ratio to each other. A novel optical molding material consisting of a resin composition containing a specific grafted polycarbonate as a main component and having a microphase dispersion of 0.5 uM or less. In particular, it has reduced optical distortion and excellent microphase dispersion. , optical discs, optical lenses, etc.

[Conventional methods and their problems]

Conventionally, acrylic resin has been known as a material for optical transparent molded products because of its transparency, good fluidity, and low birefringence (Japanese Unexamined Patent Application Publication No. 1983-1993).
-131654 etc.). However, acrylic resin has drawbacks such as low heat resistance of about 70° C., low impact resistance, and easy warping due to moisture. In addition, in order to eliminate the above-mentioned drawbacks, the use of polycarbonate resin with a viscosity average molecular weight of 15.000 to 18.000 as a molding material for discs, lenses, etc. is being considered (Japanese Patent Application Laid-Open No. 180553/1983). It has drawbacks such as high birefringence, which is considered important, and its use is limited.

One of the important issues in the practical application of optical materials, mainly optical disk materials, is the issue of reducing the noise level of the substrate itself, and it is clear that this noise level depends on birefringence including obliquely incident light. (for example,
Optics, vol 15. Nα5 (October 1986)
P441-421, Optical Memory Symposium '86 Proceedings P33-38).

In other words, the reduction in birefringence for vertically incident light does not necessarily correlate with the change in birefringence for obliquely incident light, and this difference is particularly noticeable in the case of polycarbonate resin, and it is important to reduce birefringence in a wide angle range of light. It is.

As an attempt to reduce birefringence, various methods have been proposed for modifying aromatic polycarbonate or for creating a composition of aromatic polycarbonate and other resins (for example, JP-A-6
1-19630, JP 61-19656, JP 62-18466, JP 62-20524, JP 61-108617, and Functional Materials March 1987 P.
21-29). However, all of these proposals are aimed at reducing the birefringence of vertically incident light, and do not mention the above-mentioned birefringence of obliquely incident light. From the above point of view, this is not necessarily satisfactory. What is more important is that even if the composition is simply mixed or a copolymer composition system that necessarily contains a large amount of homopolymer, the phase fraction of the components in the structure tends to be coarse. , as a result, for example, the microdispersed phase is 0.51. 3 larger than cm
- If the measured birefringence is reduced to 0, there will be a refractive index difference in a micron-sized region, that is, in each optical path, and the dispersion particle interface will become a scattering source due to the refractive index difference. This results in optical non-uniformity, which causes noise generation.

As described above, the modified polycarbonate produced by the conventional method has fundamental defects that make it difficult to use as an optical molding material, especially as a substrate for an optical disk.

[Means for solving problems]

The present inventors have conducted intensive studies on transparent optical molding materials that have low optical distortion particularly in a wide-angle range of light and have fine microphase dispersion. As a result, we found an optical molding material that has a microphase dispersion of 0.5ρ or less when the molecular weight ratio and weight composition ratio of the aromatic polycarbonate constitutional unit and the polystyrene polymer constitutional unit are in a specific range as a graft polycarbonate. , completed the present invention.

That is, the present invention provides a graft copolymer with a styrene compound having an aromatic polycarbonate as a backbone polymer having a weight average molecular weight in terms of polystyrene of 25,000 to 80,000, wherein: (1) the ratio of each partial molecular weight; However, 0.2≦PCMw/PSMw≦4 (1) (in the formula, PCMw indicates the weight average molecular weight of the aromatic polycarbonate constituent unit in terms of polystyrene, and PSMw indicates the weight average molecular weight of the styrene compound polymer constituent unit. ).

2. The ratio of each constituent unit is 30/70≦PC/PS ≦90/10 (2
) (in the formula, PC represents the weight of the aromatic polycarbonate structural unit, and PS represents the weight of the styrene compound polymer structural unit).

It is a transparent optical molding material consisting of a resin composition mainly composed of a grafted polycarbonate having a microphase dispersion of 0.5- or less, and in a preferred embodiment, the aromatic polycarbonate is a 2,2- - The structural unit is bis(4-hydroxyphenyl)propane, the styrene compound is styrene, and the absolute value of the difference in birefringence at normal incidence and oblique incidence angles of ±30° of light rays is the thickness. This is an optical molding material characterized by having a diameter of 50 nm or less at 1.2+r+m.

The aromatic polycarbonate structural unit used as the backbone polymer of the optical molding material of the present invention has a polystyrene equivalent weight average molecular weight (=PCMw, which is a value measured by the GPC method based on polystyrene described in Note 1 below) of 2.
Range of 5.000 to go, ooo (corresponds to 12.000 to 30.000 as the viscosity average molecular weight of polycarbonate resin based on the method described in Note 2 below).
, preferably from the range of 35.000 to 70.000, and furthermore, the ratio of PCMw to the weight average molecular weight (=PSMw) of the styrenic polymer graft portion satisfies the above formula (1), preferably 0.3≦ PCMw / PSMw≦3 ‥‥(1)' and weight of aromatic polycarbonate structural unit (=PC)
and the weight of the styrenic polymer constituent unit (=PS) is expressed by the above formula (2), preferably 30/To≦PC/PS≦80/20 (2
)′.

The present invention provides a good optical molding material when the polystyrene equivalent weight average molecular weight of the aromatic polycarbonate structural unit, formula <1) [(1)'] and formula (2) ((2)') are satisfied as a whole. They are mutually dependent.If these are used in a suitable combination, the birefringence should be in the ±10 nm 100 range for both normal incidence and oblique incidence (see note 3 below), and injection molding. It is also possible to create a material in which the absolute value of birefringence changes only within a range of 3Q nm or less even when the conditions, for example, the injection molding resin temperature are changed from 280 to 340°C. The meaning of these is only secondary, but to explain them, the weight average molecular weight (=P) of the aromatic polycarbonate structural unit is
If CMw) is less than 25,000, the mechanical properties as a molding material will be poor, and if it exceeds go, ooo, problems will arise in terms of moldability and the like. Formula (1) ((1)'
) is mainly correlated to the absolute value of birefringence, and outside this range, the dependence of birefringence on molding temperature becomes undesirable. In addition, Equation (2) [(2)'] mainly correlates with optical distortion in a wide angle range of light, and outside this range, the birefringence at normal incidence and oblique incidence ±30° is correlated. It is not possible to reduce the difference.

Moreover, the amount of grafted polycarbonate bodies in the molding material of the present invention is the main part. In the present invention, the minor component in the grafted polycarbonate may be PC or PS, and when a homopolymer of the same type as the minor component is blended, dispersed particles of the minor component, which are islands and holes. There is a strong tendency for the diameter to increase; conversely, this tendency is small in the case of major constituent components. Therefore, although the amount of the main portion is not uniformly defined, it is usually 30% by weight or more, preferably 50% by weight or more, and particularly preferably 80% by weight or more. The above preferred range can be easily understood from the fact that there is no phase separation when it is made into a methylene chloride solution. If the amount of the grafted polycarbonate body is less than 30% by weight, the microphase dispersion becomes coarse and exceeds 0.5p, resulting in an increase in the noise level, which is not preferable.

Next, a method for manufacturing the optical molding material of the present invention will be explained.

The graft polycarbonate resin composition used in the transparent optical molding material of the present invention has as a main component a graft copolymer with a styrene compound having an aromatic polycarbonate as a backbone polymer. There are various synthesis methods, but a typical method is to copolymerize an aromatic polycarbonate having at least one graft polymerization initiation site at the end, represented by an unsaturated double bond per molecule, and a styrene monomer. Method (Special Publication No. 48-25078, Special Publication No. 61
-33849 and Japanese Patent Application No. 62-28194, etc.).

The method for producing an aromatic polycarbonate having at least one graft polymerization initiation site at the end, represented by an unsaturated double bond per molecule on average, uses a monofunctional polycarbonate having an unsaturated double bond as a molecular weight regulator or terminal capping agent. The manufacturing method is the same as that for conventional aromatic polycarbonate resins, except that a compound containing a compound or a conventional terminal capping agent is used in combination.
It is manufactured by a solution method such as an interfacial polymerization method, a pyridine method, or a chloroformate method.

Specifically, preferred dihydric phenol compounds used in the production of the aromatic polycarbonate structural unit of the present invention include bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)ether, and bis(4-hydroxyphenyl)ether. hydroxyphenyl) sulfone, bis(4-hydroxyphenyl) sulfoxide, bis(4-hydroxyphenyl) sulfide, bis(4-hydroxyphenyl)ketone, 1,1-bis(4-hydroxyphenyl)ethane, 2
．． 2-bis(4-hydroxyphenyl)propane, 2.
2-bis(4-hydroxyphenyl)butane, 1,1-
Bis(4-hydroxyphenyl)cyclohexane, 2.
2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3,5-
dichlorophenyl)propane, 2,2-bis(4-hydroxy-3-bromophenyl)propane, 2,2-bis(4-hydroxy-3-chlorophenyl)propane, 2
．． Examples include 2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1.1-bis(4-hydroxyphenyl)-1-phenylethane, and bis(4-hydroxyphenyl)diphenylmethane, particularly 2.2 −Bis(
4-hydroxyphenyl)furopane is preferably used.

In addition, monofunctional compounds having an unsaturated double bond for introducing an unsaturated terminal group include acrylic acid, methacrylic acid, sorbic acid, acrylic acid chloride, methacrylic acid chloride, sorbic acid chloride, and allyl alcohol chloroform. carboxylic acids, acid chlorides and chloroformates such as isopropenylphenol chloroformate and hydroxystyrene chloroformate; isopropenylphenol, hydroxystyrene, hydroxyphenylmaleimide, hydroxybenzoic acid allyl ester and benzoic acid methyl allyl ester Examples include phenols having unsaturated groups. In addition to these compounds, there are compounds having a tertiary carbon or mercapto group, such as P-isopropylphenol, m-isopropylphenol, thioglycolic acid chloride, P-mercaptophenol, m-mercaptophenol, and the like. These compounds may be used in combination with conventional terminal capping agents, and are present in an amount of 1 to 25 mol %, preferably 1.5 to 10 mol %, based on 1 mol of the dihydric phenol compound described above.
It is used within the range of mol%, and methacrylic acid chloride, isopropenylphenol, and hydroxystyrene are particularly preferred.

The styrenic monomers of the present invention specifically include styrene, 0-methylstyrene, P-methylstyrene, α-methylstyrene, rope styrene, P-butylstyrene, chlorostyrene, bromostyrene, 2,4-dimethyl Examples include styrene, and styrene is particularly preferred.

In addition, in the present invention, other vinyl monomers such as methyl methacrylate, ethyl methacrylate, butyl acrylate, n-
Acrylates such as hexyl acrylate, butyl acrylate and cyclohexyl methacrylate; glycidyl methacrylate, acrylic acid, acrylamide, methacrylamide, N-methoxymethacrylamide, acrylonitrile, methacrylonitrile, maleic anhydride,
It is also possible to partially use maleimide etc.

In addition to controlling the molecular weight of the graft polymerized styrene monomer by controlling the reaction temperature or the amount of a polymerization initiator described later, an organic sulfur compound can be used as a molecular weight regulator. Preferred organic sulfur compounds are aliphatic or aromatic compounds having 1 to 30 carbon atoms, specifically n-butyl mercaptan, imbutyl mercaptan, n-octyl mercaptan, n-
dodecyl mercaptan, 5ec-butyl mercaptan,
Primary, secondary, and tertiary mercaptans such as 5ec-dodecylmercaptan and tert-butylmercaptan; Aromatic mercaptans such as phenylmercaptan, thiocresol, and 4-tert-butylthiocresol; Thioglycolic acid and its esters; Ethylene thioglycol Among these compounds, n-butyl mercaptan, te
rt-butyl mercaptan and n-octyl mercaptan are most preferred, and the amount used is not more than 5 weight of the total amount of the aromatic polycarbonate resin having a terminal unsaturated group and the styrene monomer, preferably 0.000.
It is in the range of 4 to 1% by weight, and if it is used in excess of 5% by weight, the degree of polymerization will decrease and mechanical properties will deteriorate, which is not preferable.

In addition to thermal polymerization, a polymerization initiator can be used as a means for graft polymerizing a styrenic monomer to an aromatic polycarbonate. Examples of such a polymerization initiator include di-tert-butyl peroxide,
Dicumyl peroxide, methyl ethyl ketone peroxide, di-tert-butyl perphthalate, lauroyl peroxide, oxy)hexane, t-butyl peroxylaurate, di-tert-amyl peroxide, dicumyl peroxide, tert-butyl cumyl peroxide , organic peroxides such as benzoyl peroxide; 2.2-azobisisobutyronitrile, 1
, 1-azobiscyclohexanecarbonitrile, and 2-cyano-2-propylazoformamide, and the amount used is generally 1% by weight or less.

The grafted polycarbonate of the present invention is produced in the presence of an aromatic polycarbonate having at its end a graft initiation point represented by at least one unsaturated double bond per molecule on average as explained above, and if necessary, an organic sulfur-based polycarbonate. Except for the use of a polymerization regulator and/or a polymerization initiator, it is manufactured by the same manufacturing methods as conventional polystyrene resins, such as bulk polymerization, solution polymerization, suspension polymerization, and emulsion polymerization.

〔Example〕

Hereinafter, this will be explained in detail using examples and the like.

The styrene equivalent weight average molecular weight, viscosity average molecular weight, birefringence, and microphase dispersion in the present invention were determined by the following methods.

Note 1: Weight average molecular weight in terms of styrene.

G, P, and C0 are the weight average molecular weights obtained using polystyrene standard samples.

The weight average molecular weight of the polystyrene constituent units in the grafted polycarbonate composition was determined by a method in which the polycarbonate constituent parts in the grafted polycarbonate were decomposed with an amine and the remaining polystyrene was measured.

Note 2: Viscosity average molecular weight.

The viscosity average molecular weight was determined by the following method.

(1) Measurement of solution viscosity Sample solution: Methylene chloride solution with concentration Q, 5 g/d1.

Viscometer: Flow time of methylene chloride only 72, 36
Second capillary type improved Ubbelohde viscometer.

Measurement temperature: 20℃±0.01℃ Through this measurement, the flow time of the sample solution is measured, and η
Find rsL.

(2), Calculation From η4 measured above, calculate the area from formulas ■ and ■,
(2) Find My from (Schnell's formula).

? ? , P = T/To −1, ηrsL= T/T
o −−−■η,, /C=(3)+′(3)2C・
...■(3) = M, ...■Note 3 = Birefringence, according to the following method.

(1), Sample, equipment, etc.Target sample: Injection molded disk with a thickness of 1.2 mm and a diameter of 130M Measurement wavelength: 632.8 nm Measurement equipment: @Manufactured by Shotoku Kogaku Kogyo Co., Ltd., automatic ellipsometer (2), normal incidence and oblique Incident birefringence (■), vertical incidence birefringence (Re0); Represents the birefringence when the incident angle of light is horizontal angle H=0° and vertical angle V=0° with respect to the sample surface.

Note that the horizontal angle means an angle in the radial direction of the disk, and the vertical angle means an angle perpendicular to the radial direction of the disk.

2. Oblique incidence birefringence (Re'''11M3G); Four types of birefringence and normal incidence birefringence (Re''' ) indicates the maximum absolute value of the difference.

Note 4: Microphase dispersion.

Measured using an electron microscope. , Reference Examples 1 to 4 Dissolve 22 kg of sodium hydroxide in 2651 of water,
While keeping at 0°C, 45.6 kg of 2,2-bis(4-hydroxyphenyl)propane (=BPA),
Hydrosulfide) 50g was dissolved.

150 Il of methylene chloride was added thereto, and phosgene was blown into the mixture while stirring. After 30 minutes, 125 kg of methylene chloride containing 1.95 kg of P-isopropenylphenol was added, and phosgene was blown into the mixture for another 30 minutes.

After the phosgene injection was completed, the reaction solution was vigorously stirred to emulsify it, and after emulsification, a 1% triethylamine methylene chloride solution 31 was added, and the mixture was stirred for about 1 hour to allow polymerization.

The polymerization solution was separated into an aqueous phase and an organic phase, and the organic phase was neutralized with phosphoric acid, washed with water several times, and then dropped into methanol to precipitate the copolymer, filtered, and dry-lit. A white powder was obtained.

The weight average molecular weight of this powder in terms of polystyrene is 32.0
00, and the viscosity average molecular weight was 16.000.

Similarly, the weight average molecular weight (viscosity average molecular weight) in terms of polystyrene was 45.000 (20,000), 49.500 in the same manner except that the amount of terminal stopper used etc. was changed.
(22,000) and 54,000 (24,000)
A terminally unsaturated polycarbonate was obtained.

These are listed below in descending order of viscosity average molecular weight.
They are called CI, PC2, PC3, and PC4.

Reference Example 5 In Reference Example 1, acrylic acid chloride was used instead of P-isopropenylphenol, and the weight average molecular weight (viscosity average molecular weight) in terms of polystyrene was determined according to Reference Example 1.
A terminally unsaturated polycarbonate having a polycarbonate of 49.500 (22,000) was obtained (hereinafter referred to as PC5).

Example 1.2 2.5 kg of PCI synthesized in Reference Example 1 and 11 kg of styrene monomer (hereinafter referred to as St) were placed in a polymerization reactor, and after purging with nitrogen, the temperature was raised to 120 ° C. with stirring, n-dodecyl mercaptan (hereinafter referred to as NOS)
The reaction was continued for 1.5 hours while adding 270 g of styrene monomer containing 10.8 g.

After the reaction was completed, the product was cooled and precipitated by adding it to methanol to obtain 3.57 kg of polymer with PC:PS=70:30.
I got it.

The weight average molecular weight of the polystyrene portion in this polymer (hereinafter referred to as G1) was 40.000.

A polymer (hereinafter referred to as G2) having PC:PS=60:40 was obtained in the same manner except that the amount of the molecular weight regulator NOS used and the reaction time were changed. The weight average molecular weight (PSMw) of the polystyrene part in G2 is go, o
It was oo.

Example 3.4 PC22.5kg and St l1 synthesized in Reference Example 2
kg was placed in a polymerization reactor, the atmosphere was replaced with nitrogen, the temperature was raised to 120°C with stirring, and St containing 5.4 g of NDS was
The reaction was continued for 1.1 hours while adding 135 g.

After the reaction was completed, the product was cooled and precipitated by adding it to methanol to obtain 3.33 kg of polymer with PC:PS=75:25.
I got it. PSMw of this polymer (hereinafter referred to as G3)
was 60,000.

A polymer (hereinafter referred to as G4) having a ratio of PC:PS=65:35 was obtained in the same manner except that the amount of the molecular weight regulator NDS used and the reaction time were changed. G4 PSMw
was 30°000.

Example 5.6 PC32.5kg and St 11 synthesized in Reference Example 3
kg into a polymerization reactor, and after purging with nitrogen, the temperature was raised to 120°C with stirring, and St containing 11.4 g of NDS was
The reaction was continued for 2.3 hours while adding 285 g.

After the reaction was completed, the product was cooled and precipitated by adding it to methanol to obtain 4.17 kg of polymer with PC:PS=60:40.
I got it. PSMw of this polymer (hereinafter referred to as G5)
was 60,000.

A polymer having PC:PS=55:45 (hereinafter referred to as G4) was obtained in the same manner except that the amount of the molecular weight regulator NDS used and the reaction time were changed. G6's PSMw is 80
It was ゜000.

Example 7 32.5 kg of PC synthesized in Reference Example 3 was suspended in St and P
The concentration of C3 was 10% by weight.

This suspension was continuously introduced into a pipe reactor equipped with a static mixer maintained at 150-165° C. with an average residence time of 10 minutes.

The distilled reaction solution was poured into methanol, precipitated, and PC:
A polymer (hereinafter referred to as G7) with PS=50:50 was obtained. The PSMw of GV was 80.000.

Example 8 PC52.5kg and St l1 synthesized in Reference Example 5
kg was placed in a polymerization reactor, the atmosphere was replaced with nitrogen, the temperature was raised to 120°C with stirring, and St containing 8.6 g of NDS was
The reaction was continued for 2.3 hours while adding 215 g.

After the reaction was completed, the product was cooled and precipitated by adding it to methanol to obtain 4.17 kg of polymer with PC:PS=60:40.
I got it. PSMw of this polymer (hereinafter referred to as G8)
was go, ooo.

Example 9.10 PC42.5kg and St 11 synthesized in Reference Example 4
kg into a polymerization reactor, and after purging with nitrogen, the temperature was raised to 120°C with stirring, and St containing 8.6 g of NDS was
The reaction was continued for 2.2 hours while adding 215 g.

After the reaction was completed, the product was cooled and added to methanol to precipitate it, resulting in a polymer with PC: PS = 60:40 4.17
I got kg. PS of this polymer (hereinafter referred to as G9)
Mw was go, ooo.

A polymer having PC:PS=50:50 (hereinafter referred to as GIO) was obtained in the same manner except that the amount of the molecular weight regulator NDS used and the reaction time were changed. The PSMw of GIO was 120,000.

Example 11 The grafted polycarbonate resin compositions of 61 to GIO obtained in Examples 1 to 10 were fed to a 20 mm vented extruder and pelletized at a cylinder temperature of 240 to 260°C.

After drying the pellets at 110°C for more than 5 hours, each specimen disk was prepared by injection molding at a cylinder temperature of 290 to 340°C and a mold temperature of 90°C.
Birefringence and microphase dispersion at any point on a 2 mm concentric circle were measured.

The measurement results are shown in Table 1.

Furthermore, Table 2 shows the measurement results of birefringence when dry pellets of the G6 grafted polycarbonate resin composition were used and the cylinder temperature was varied within the range shown in Table 2.

Comparative Example 1.2 Polycarbonate resin (manufactured by Mitsubishi Gas Chemical Co., Ltd., trade name: Nipiron H-4000, polystyrene equivalent weight average molecular weight 28,000, hereinafter referred to as PCO2) alone (Comparative Example 1) and this PCO2 and carboxylic acid derivative Polystyrene resin containing
32, weight average molecular weight 250.000) =80=20
The mixture was blended and dried, and pelletized at a cylinder temperature of 250°C.

Table 1 also shows the results of these tests in the same manner as in the Examples.

Incidentally, the disk of Comparative Example 2 had bluish cloudiness, and it was clear from visual inspection that it was unsuitable as a transparent optical material.

Comparative Example 3 Polycarbonate resin (manufactured by Mitsubishi Gas Chemical ■, trade name: Nipiron B-2000, polystyrene equivalent weight average molecular weight 63,000, principal polarizability difference: 110x 10-"d
, hereinafter referred to as PCE2) and polystyrene resin (manufactured by Sanyo Chemical Industries, Ltd., trade name: Hymer 5T-95, weight average molecular weight 10.000, principal polarizability difference: -120X10-"
crl) = 50:50, dried, pelletized at a cylinder temperature of 250°C,
A molding resin of 14w=6.3 was obtained.

The results obtained in the same manner as in Example 5 are shown in Table 1.

From Comparative Example 3, it is easily understood that birefringence does not necessarily depend on the positive and negative phase reduction effect of the difference in principal polarizability of the resin.

Table 2 [Operations and Effects of the Invention] As is clear from the detailed description of the invention, Examples, and Comparative Examples, the optical molding material containing the grafted polycarbonate of the present invention as a main component can withstand normal incidence and oblique incidence. The birefringence difference is significantly reduced, and its absolute value can be easily set within ±10 nm, and the microphase dispersion is also extremely fine particle dispersion. Therefore, not only the noise level due to birefringence is reduced, but also the generation of noise due to optical non-uniformity is significantly reduced.

Furthermore, since the dependence of the birefringence on the injection molding temperature is also significantly reduced, it can be seen that it can be extremely suitably used as an optical disk, an optical lens material, etc.

Claims (1)

[Scope of Claims] 1. Weight average molecular weight in terms of polystyrene is 25,000 or more
A graft copolymer with a styrene compound having an aromatic polycarbonate having a molecular weight of 80,000 as a backbone polymer, 1. The ratio of each partial molecular weight is 0.2≦PCMw/PSMw≦4 (1) (P in the formula
CMw indicates the weight average molecular weight of the aromatic polycarbonate structural unit in terms of polystyrene, and PSMw indicates the weight average molecular weight of the styrene compound polymer structural unit). 2. The ratio of each structural unit is 30/70≦PC/PS≦90/10 (2) (in the formula, PC represents the weight of the aromatic polycarbonate structural unit, and PS represents the styrene compound polymer structural unit. weight). A transparent optical molding material comprising a resin composition containing grafted polycarbonate as a main component, and having a microphase dispersion of 0.5 μm or less. 2. The aromatic polycarbonate is 2,2-bis(4-
The optical molding material according to claim 1, which is a structural unit consisting of (hydroxyphenyl)propane. 3. The optical molding material according to claim 1 or 2, wherein the styrenic compound is styrene. 4. The optical molding material according to claim 1, 2 or 3, wherein the absolute value of the difference in birefringence between normal incidence and oblique incidence angles of light rays of ±30° is 50 nm or less at a thickness of 1.2 mm.