JPH09268225A - Oxaspiroundecane group-containing polycarbonate copolymer and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject copolymer low in double refraction due to a small photoelasticity effect and low in molding strain, excellent in optical properties, having heat resistance and mechanical strength, containing an oxaspiroundecane group. SOLUTION: This polycarbonate copolymer comprises 5-95mol% of a repeating unit of formula I and 95-5mol% of a repeating unit of formula II [R<1> is H, a 1-6C alkyl, etc.; R<2> and R<3> are each independently H or a 1-6C alkyl; A-O comprises a single bond of A and oxy group or is O (2-4C alkylene)- O- group; X is a group of formula III (R<4> and R<5> are each independently H, a 1-6C alkyl or a 6-10C aryl), O, S, S0, etc.] and has at least 0.3dl/g reduced viscosity (ηsp /c) in 0.5g/dl solution in methylene chloride as a solvent at 20 deg.C, <=70×10<-13> cm<2> /dyne photoelasticity coefficient and at least 95 deg.C glass-transition temperature. The polycarbonate copolymer is used as a material to give an information transmission medium and an information recording medium.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a polycarbonate copolymer containing an oxaspiroundecane group and a method for producing the same. More specifically, it relates to a novel polycarbonate copolymer having excellent optical properties and an industrially advantageous efficient production method thereof.

[0002]

2. Description of the Related Art Polycarbonate resins produced by reacting 2,2-bis (4-hydroxyphenyl) propane (commonly known as bisphenol A) with phosgene or a carbonate-forming compound such as diphenyl carbonate are known for their transparency and heat resistance. And because of its excellent mechanical strength, it is used for a wide range of applications.

[0003] However, with the expansion of various applications, the required properties of polycarbonate resins have become strict, and the appearance of polycarbonate resins having better performance has been demanded. Particularly, when a molded product is obtained by injection molding using a conventional polycarbonate resin, the molded product tends to have a large stress optical distortion, that is, a large birefringence, and such an optical distortion becomes a problem. There is a problem that it is not preferable as a material for optical equipment.

US Pat. No. 2,945,008 discloses a polyester comprising the following repeating units.

[0005]

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In Example 3 of this US Patent, spiroglycol having the structure of the above formula and diethyl carbonate are polycondensed with sodium ethyloxy as a catalyst.
It is described that a crystalline polycarbonate was obtained which melts at 0-270 ° C.

Japanese Unexamined Patent Publication (Kokai) No. 4-8761 discloses a polycarbonate composition having excellent transparency and strength, which comprises an aromatic polycarbonate and a glass filler having a refractive index of 1.57 or more. In Synthesis Example 2 of the same publication, bisphenol A4.
4 kg, 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane dibenzoate or spiroglycol dibenzoate (SGOB) 7. 0 kg, p
It is disclosed that from 168 g of -tert-butylphenol and 3.8 kg of phosgene, a white powdery polycarbonate copolymer was obtained by an interfacial polycondensation method.

US Pat. No. 4,495,345 discloses an optical resin composition containing polycarbonate as a main component. This polycarbonate is 230 ℃
Under a condition of 5 kgf, the melt flow rate measured by ISO R-1133 is 5.0 g / 10 minutes or more, and the glass transition temperature is 100 ° C. or more.
As specific examples of this polycarbonate, polycarbonate of bisphenol A and polycarbonate of tetrachlorobisphenol A are only disclosed.

[0009]

Therefore, an object of the present invention is to provide a novel polycarbonate copolymer having excellent optical properties. Another object of the present invention is to provide a polycarbonate copolymer having excellent transparency and a small photoelastic coefficient. Still another object of the present invention is to have excellent optical properties as described above, moldability, heat resistance,
It is to provide a polycarbonate copolymer having excellent mechanical strength. Still another object of the present invention is to provide a method for industrially and efficiently producing the polycarbonate copolymer of the present invention having the above-mentioned excellent properties. Still another object of the present invention is to provide use of the above-mentioned polycarbonate copolymer of the present invention as a material for an information transmission medium or an information recording medium. Further objects and advantages of the present invention will be apparent from the following description.

[0010]

According to the present invention, the above objects and advantages of the present invention are as follows.

[0011]

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Repeating units of 5 to 95 mol% and the following formula (II)

[0013]

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[Where R ¹ is a hydrogen atom and has 1 to 6 carbon atoms]
Is an alkyl group or an aryl group having 6 to 10 carbon atoms,
R ² and R ³ are each independently a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and —A—O— means that A is a single bond and represents an oxy group (—O—); -(Carbon number 2
~ 4 alkylene group) -O-group,

[0015]

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It is essentially composed of 95 to 5 mol% of the repeating unit represented by the following formula, and 0.5 g / methylene chloride is used as a solvent.
Reduced viscosity (η _sp / c) of dl-concentration solution at 20 ° C
Is at least 0.3 dl / g and the photoelastic coefficient is 70
Achieved by a polycarbonate copolymer characterized in that it is less than or equal to × 10 ^-13 cm ² / dyne and has a glass transition temperature of at least 95 ° C.

The polycarbonate copolymer of the present invention has the repeating unit of the above formula (I) and the above formula (I) as described above.
It essentially consists of the repeating unit of I). In the above formula (II), R ¹ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms.

The alkyl group having 1 to 6 carbon atoms may be linear or branched, and examples thereof include methyl group, ethyl group, n-propyl group, iso-propyl group,
n-butyl group, iso-butyl group, sec-butyl group,
Examples thereof include tert-butyl group, n-pentyl group and n-hexyl group.

Examples of the aryl group having 6 to 10 carbon atoms include phenyl group, tolyl group, xylyl group, cumyl group and naphthyl group.

R ² and R ³ are the same or different and each is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Specific examples of the alkyl group having 1 to 6 carbon atoms are the same as those exemplified for R ¹ above.

The group —A—O— represents a oxy group (—O—) in which A is a single bond, or represents —O— (alkylene group having 2 to 4 carbon atoms) —O— group. Examples of the alkylene group having 2 to 4 carbon atoms in the latter group include, for example,
Examples thereof include 1,2-ethylene, 1,1-ethylene, 1,3-trimethylene, 1,2-propylene, and 1,4-tetramethylene.

The group represented by X:

[0023]

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[Wherein R ⁴ and R ⁵ are the same or different and each is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms. ], The alkyl group having 1 to 6 carbon atoms of R ⁴ and R ⁵ and 6 carbon atoms
As the aryl group of 10 to 10, the same groups as those exemplified above for the group R ¹ can be exemplified.

The group represented by X:

[0026]

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Preferred examples include a 1-phenyl-1-methylmethylene group, a propylmethylene group and a 2,2-propylidene group.

The group represented by X:

[0029]

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[Wherein R ⁶ , R ⁷ and R ⁸ are the same or different and each is a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and n is 0 or 1]. ], R ⁶ ,
Examples of the alkyl group having 1 to 6 carbon atoms for R ⁷ and R ⁸ include the same groups as those exemplified for R ¹ .

[0031]

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As, for example, a cyclohexylidene group,
A 3,3,5-trimethyl-1,1-cyclohexylidene group can be mentioned as a preferable example.

X is, in addition to the above,

[0034]

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It may be a group represented by:

The repeating unit represented by the above formula (II) is, for example,

[0037]

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[0038]

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[0039]

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[0040]

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[0041]

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[0042]

[Chemical 21]

[0043]

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[0044]

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The following may be mentioned as preferable ones.

These repeating units (A) to (P) represented by the formula (II) can be present in one kind or two or more kinds in the polycarbonate copolymer of the present invention. In particular, as the repeating unit represented by the formula (II), a second repeating unit selected from the group consisting of the above (A) to (M) and the above (N) to (P).
Particularly preferred is a combination with a repeating unit of.

Therefore, the present invention provides a polycarbonate copolymer in which the repeating unit represented by the above formula (II) is at least one first repeating unit selected from the group consisting of the formulas (A) to (M). Include.

The present invention also provides a polycarbonate copolymer in which the repeating unit represented by the above formula (II) is at least one second repeating unit selected from the group consisting of formulas (N) to (P). Include.

Further, in the present invention, the repeating unit represented by the above formula (II) is the first repeating unit and the second repeating unit.
A polycarbonate copolymer in combination with a repeating unit of.

The polycarbonate copolymer of the present invention contains 5 to 95 mol% of the repeating unit represented by the formula (I) and 95 to 5 mol% of the repeating unit represented by the formula (II).
Consists of The repeating unit represented by the formula (I) is 5
If it is less than mol%, desired optical properties cannot be obtained, and if it exceeds 95 mol%, mechanical strength and polymerizability become insufficient.

The repeating unit represented by the above formula (I) is preferably 7 to 93 mol%, more preferably 10 to 80 mol%.
Mol%, particularly preferably 15 to 75 mol%, and the repeating unit represented by the formula (II) is preferably 93 to 7
Particularly advantageous are those consisting of mol%, more preferably 90 to 20 mol%, particularly preferably 85 to 25 mol%.

When the repeating unit represented by the formula (II) is a combination of the first repeating unit and the second repeating unit, the repeating unit represented by the formula (I) and the first repeating unit The total number of repeating units is at least 50 mol%
It is especially preferred that the second repeating unit accounts for 50 mol% or less. Here, the ratio of the repeating unit represented by the above formula (I) and the first repeating unit is 95 to 5 mol% for the former and 5 to 95% for the latter with respect to the total amount of the former and the latter.
It can be mol%.

The polycarbonate copolymer of the present invention is a solution of a solution of 0.5 g / dl in methylene chloride as a solvent.
The reduced viscosity (η _sp / c) measured at 0 ° C. is at least 0.
3 dl / g. Preferred reduced viscosity is 0.3d
It is in the range of 1 / g to 1.0 dl / g.

Further, the polycarbonate copolymer of the present invention has a photoelastic coefficient of 70 × 10 ^-13 cm ² / dyne or less. 1 × 10 ^-13 cm ² / dyne is 1 Brews
70x10 because it is known as ters (B)
^-13 cm ² / dyne or less can be described as 70 B or less.

The photoelastic coefficient was determined by applying a tensile stress of different magnitude to a polycarbonate copolymer test piece (10 mm × 100 mm × 1 mm) in the lengthwise direction, measuring the birefringence generated, and calculating the following formula:

[0056]

## EQU1 ## C = (n ₁ −n ₂ ) / (σ ₁ −σ ₂ ).

[Where C is the photoelastic coefficient, n ₁ and n ₂ are the birefringences at the first and second tensile stresses, respectively, and σ ₁ and σ ₂ are the first and the second, respectively. Represents tensile stress (dyne / cm ² ). ]
Is calculated from

The photoelastic coefficient is preferably 60 B or less, more preferably 50 B or less.

Further, the polycarbonate copolymer of the present invention has a glass transition temperature of at least 95 ° C. The glass transition temperature is preferably at least 110 ° C, more preferably at least 120 ° C.

The polycarbonate copolymer of the present invention can be industrially advantageously produced by the following production method of the present invention.
That is, according to the present invention, secondly, the following formula (III)

[0061]

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3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane represented by the following formula (IV)

[0063]

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[Where R ¹ , R ² , R ³ , X and A
Has the same definition as in formula (II). ] And bisphenols represented by the following formula (V)

[0065]

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[Wherein Ar ¹ and Ar ² are the same or different and each is a phenyl group or a naphthyl group, and these groups are a chlorine atom, an alkyl group having 1 to 6 carbon atoms, a methoxycarbonyl group and an ethoxycarbonyl group. It may be substituted with at least one selected from the group consisting of ] And a diaryl carbonate represented by
5 to 95 mol% of the compound of the above formula (III) and 95 to 5 mol% of the compound of the above formula (IV) based on the total amount of the compound of the above formula (III) and the above formula (IV), and the above formula The compound of the formula (V) was used in a proportion of 1.0 to 1.3 mol per 1 mol of the total of the compound of the formula (III) and the compound of the formula (IV), and melt-polycondensed to obtain a reduced viscosity. Also provided is a method of making a polycarbonate copolymer, which is characterized by producing a polycarbonate that is at least 0.3 dl / g.

The compound represented by the above formula (III) is available as a white powder having a melting point of about 208 ° C.

In the above formula (IV), R ¹ , R ² ,
The definitions of R ³ , X and A are the same as those in the above formula (II).

Examples of the compound represented by the above formula (IV) include 1-phenyl-1,1-bis (4-hydroxyphenyl) ethane and 1,1-bis (4-hydroxyphenyl) 3,3,5- Trimethylcyclohexane, 1,
1-bis (3-tert-butyl-4-hydroxy-6)
-Methylphenyl) butane, 2,2-bis (3,5-dimethyl-4-hydroxyphenyl) propane, 1,1-
Bis (4-hydroxyphenyl) fluorene, 1,1-
Bis (4-hydroxyphenyl) cyclohexane, 1,
1-bis (4-hydroxy-3-methylphenyl) cyclohexane, 1,4-bis [2- (4-hydroxyphenyl) propyl] benzene, 1,3-bis [2- (4-
Hydroxyphenyl) propyl] benzene, 2,2-bis (3-tert-butyl-4-hydroxyphenyl)
Propane, 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxy-)
3-phenylphenyl) propane, 1,1-bis [4-
Examples thereof include (2-hydroxyethyloxy) phenyl] fluorene, 2,2-bis (4-hydroxyphenyl) propane, bis (4-hydroxyphenyl) ether and bis (4-hydroxyphenyl) sulfone.

In the above formula (V), Ar ¹ and Ar
² are the same or different, and the phenyl group is a naphthyl group. These groups may be substituted with a chlorine atom, an alkyl group having 1 to 6 carbon atoms, a methoxycarbonyl group or an ethoxycarbonyl group. These substituents may be one kind or two
More than a species. Examples of the alkyl group having 1 to 6 carbon atoms are the same as those described above for R ^{1 in} formula (I).

Examples of the compound represented by the formula (V) include diphenyl carbonate, di-p-tolyl carbonate, phenyl-p-tolyl carbonate and di-p-.
Preferable examples include chlorophenyl carbonate, di (2-methoxycarbonylphenyl) carbonate, phenyl-2-methoxycarbonylphenyl carbonate, di (2-ethoxycarbonylphenyl) carbonate and dinaphthylcarbonate.

In the method of the present invention, the compound of the formula (V) is added to 1 mole of the compound of the formula (III) and the compound of the formula (IV) in total.
The diaryl carbonates are used in a ratio of 1.0 to 1.3 mol. The preferred ratio within this range is
It is 1.005 to 1.10 mol.

Further, the above-mentioned formula (III) which is a diol component
The compound of formula (IV) and the compound of formula (IV) are 5 to 95 mol% of the compound of formula (III) and formula (I
The compound of V) is used at 95-5 mol%. A preferred ratio is 10 to 80 mol% of the compound of formula (III) and 90 to 20 mol% of the compound of formula (V).

Melt polycondensation of these compounds is preferably carried out in the presence of catalysts. As such a catalyst, a catalyst usually used in esterification reaction and transesterification reaction can be used. Examples of such compounds include alkali metal compounds, alkaline earth metal compounds, nitrogen-containing basic compounds, zinc compounds, boron compounds, aluminum compounds, silicon compounds, germanium compounds, organotin compounds, lead compounds. And titanium compounds, osmium compounds, antimony compounds and zirconium compounds. Among these, alkali metal compounds, alkaline earth metal compounds and nitrogen-containing basic compounds are particularly preferably used.

Examples of alkali metal compounds and alkaline earth metal compounds include hydroxides, hydrogen carbonates, carbonates, acetates, borohydrides, stearates, benzoic acid and salts of bisphenols of these metals. Etc. can be mentioned.

Specific examples of the alkali metal compound include sodium hydroxide, potassium hydroxide, lithium hydroxide, sodium hydrogen carbonate, potassium hydrogen carbonate, lithium hydrogen carbonate, sodium carbonate, potassium carbonate, lithium carbonate, sodium acetate, Potassium acetate, lithium acetate, sodium stearate, potassium stearate, lithium stearate, sodium benzoate, potassium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, bisphenol A Disodium salt, dipotassium salt, dilithium salt, phenol sodium salt, potassium salt, lithium salt and the like.

Specific examples of the alkaline earth metal compound include calcium hydride, barium hydroxide, magnesium hydroxide, strontium hydroxide, calcium hydrogen carbonate, barium hydrogen carbonate, magnesium hydrogen carbonate, strontium hydrogen carbonate. Examples thereof include calcium carbonate, barium carbonate, magnesium carbonate, strontium carbonate, calcium acetate, barium acetate, magnesium acetate, strontium acetate, calcium stearate, barium stearate, magnesium stearate and strontium stearate.

Further, as the nitrogen-containing basic compound, for example, tetramethylammonium hydroxide (Me ₄ N
OH), tetraethylammonium hydroxide (Et
₄ NOH), tetrabutylammonium hydroxide (Bu ₄ NOH), trimethylbenzylammonium hydroxide (phenyl-CH ₂ (Me) ₃ NOH), and other ammonium hydroxides having alkyl, aryl, araryl groups, etc., trimethylamine, triethylamine , Tertiary amines such as dimethylbenzylamine and triphenylamine; formula R ₂ NH (wherein R is methyl,
Secondary amines represented by alkyl such as ethyl and aryl groups such as phenyl and toluyl; Formula RNH
₂ (wherein R is the same as above); 2-thymerimidazole, 2-phenylimidazole and other imidazoles; tetramethylammonium acetate (Me ₄ NOCOCH ₃ ) and other ammonium carboxylates Or tetramethylammonium borohydride (Me ₄ NBH ₄ ), tetrabutylammonium tetraphenylborate (Me ₄ NBPh)
₄ ) and other basic salts. These compounds may be used alone or in combination of two or more.

In the case of using an alkali metal compound and / or an alkaline earth metal compound, these catalysts are used in an amount of 1 × 10 ⁻⁷ to 1 × 10 ⁻⁴ equivalent per mol of the diol component.
It is preferably selected in the range of 1 × 10 ^{−6 to} 5 × 10 ⁻⁵ equivalents.

The melt polycondensation reaction is carried out by distilling off the monohydroxy compound produced by stirring under heating in an inert gas atmosphere as is conventionally known.
The reaction temperature is usually in the range of 120 to 350 ° C., and in the late stage of the reaction, the degree of reduced pressure of the system is increased to 10 to 0.1 Torr to facilitate the distillation of the monohydroxy compound produced and complete the reaction.

According to the method as described above, the novel polymer of the present invention can be obtained. Antioxidants, if necessary
Additives such as an ultraviolet absorber and a release agent can be added.

The present invention provides an information transmission medium and an information recording medium made of the above-mentioned novel polycarbonate copolymer. That is, the novel polycarbonate polymer of the present invention can be advantageously used as an information transmission medium such as an optical fiber material or an information recording medium such as an optical disk material because of its excellent transparency.

[0083]

EXAMPLES The present invention will be described in more detail with reference to Examples and Comparative Examples.

[Example 1] 3,9-as the diol component
Bis (1,1-dimethyl-2-hydroxyethyl-2,
152 parts by weight of 4,8,10-tetraoxaspiro [5.5] undecane (hereinafter referred to as spiroglycol) (0.
5 mol) and 114 parts by weight (0.5 mol) of 2,2-bis (4-hydroxyphenyl) propane (Bis-A), 225 parts by weight of diphenyl carbonate (1.05 mol) as a carbonic acid ester forming compound, and After 9.1 × 10 ⁻³ parts by weight of tetramethylammonium hydroxide and 4 × 10 ⁻⁴ parts by weight of sodium hydroxide as a catalyst were charged into a reaction tank equipped with a stirrer, a rectification column and a decompressor, and the atmosphere was replaced with nitrogen. Heated and melted. After stirring for 30 minutes, the internal temperature is 180 ℃
The temperature was gradually reduced while increasing the temperature, and the reaction was carried out at 100 mmHg for 30 minutes while distilling off the produced phenol.

Next, after the temperature was raised to 200 ° C., the pressure was gradually reduced, and the reaction was carried out at 50 mmHg for 20 minutes while distilling phenol off. Further, the temperature was gradually raised and reduced to 220 ° C./30 mmHg, and the same temperature and pressure were applied for 20 minutes.
The reaction was continued by repeatedly raising the temperature and reducing the pressure to 10 mmHg, 260 ° C./1 mmHg or less by the same method as above, and finally reacting at 260 ° C./1 mmHg or less for 2 hours.

The polymer obtained had a reduced viscosity [η _sp / c] of 0.2 at 20 ° C. in a solution containing methylene chloride as a solvent.
It was 45 dl / g. The glass transition temperature of the obtained polymer was 114 ° C. as measured by a DuPont thermal analyzer (2000 type DSC). Further, the polymer was dissolved in thylene chloride, cast into a film having a thickness of 100 μm, and measured with a photoelastic coefficient measuring device (PA-150) manufactured by Riken Keiki Co., Ltd.
It was a low value of × 10 ^-13 cm ² / dyne (3OB). (The same measurement was carried out for the following examples and comparative examples.)

Examples 2 to 17 Polycarbonate polymers having the properties shown in Tables 1 to 8 were obtained in the same manner as in Example 1 using the raw materials shown in Tables 1 to 8.

[0088]

[Table 1]

[0089]

[Table 2]

[0090]

[Table 3]

[0091]

[Table 4]

[0092]

[Table 5]

[0093]

[Table 6]

[0094]

[Table 7]

[0095]

[Table 8]

[Comparative Example 1] 2,2-as the diol component
A polymer was obtained by carrying out the reaction by the same operation as in Example 1 except that only 228 parts by weight of bis (4-hydroxyphenyl) propane was used.

The polymer obtained had a reduced viscosity [η _sp / c] of 0.2 at 20 ° C. in a solution containing methylene chloride as a solvent.
It was 49 dl / g. The polymer obtained had a glass transition temperature of 149 ° C. and a photoelastic coefficient of 79 × 10 ⁻¹³ cm.
It was a high value of ² / dyne.

[Comparative Example 2] The reaction was carried out in the same manner as in Example 1 except that 152 parts by weight (0.5 mol) of spiroglycol was used as the diol component, but crystallization occurred during the polymerization. .

The polymer obtained had a reduced viscosity [η _sp / c] of 0.2 at 20 ° C. in a solution containing methylene chloride as a solvent.
It was 25 dl / g. The glass transition temperature of the obtained polymer was as low as 92 ° C., and the degree of polymerization was also low, so the strength was insufficient, and a film having a strength sufficient for measuring the photoelastic coefficient could not be prepared.

[0100]

As described above, the polycarbonate copolymer of the present invention is superior to conventional polycarbonate resins in that
Since the photoelastic effect is small and the molding strain is small, the birefringence is small and the optical properties are extremely excellent.

Polycarbonate synthesized from spiroglycol and a carbonic acid ester-forming compound was inferior in heat resistance and mechanical strength. However, by copolymerizing with an aromatic compound as in the present invention, excellent optical properties can be obtained. A polycarbonate having sufficient heat resistance and mechanical strength can be obtained without impairing the properties.

Therefore, the polycarbonate of the present invention can be used as a material for optical devices such as optical discs.
It can be effectively used as a material for various industrial equipment.

 ────────────────────────────────────────────────── ─── Continuing from the front page (72) Inventor Katsushi Sasaki 2-1 Hinodecho, Iwakuni-shi, Yamaguchi Prefecture Teijin Limited Iwakuni Research Center

Claims (4)

[Claims] 1. A compound represented by the following formula (I): 5 to 95 mol% of the repeating unit represented by the following formula (II) [Here, R ¹ is a hydrogen atom, an alkyl group having 1 to 6 carbon atoms or an aryl group having 6 to 10 carbon atoms, and R ² and R ^2
3 are, independently of each other, a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and —A—O— is an oxy group (—
O--) or --O-- (alkylene group having 2 to 4 carbon atoms) --O-- group, and The repeating unit represented by formula (5) has a reduced viscosity (η _sp / c) at 20 ° C of at least 0.5 g / dl concentration of a solution containing methylene chloride as a solvent.
A polycarbonate copolymer, which has a photoelastic coefficient of 70 × 10 ⁻¹³ cm ² / dyne or less and a glass transition temperature of at least 95 ° C. 2. The following formula (III): 3,9-bis (1,1-dimethyl-2-hydroxyethyl) -2,4,8,10-tetraoxaspiro [5.5] undecane represented by the following formula (IV): [Here, the definitions of R ¹ , R ² , R ³ , X and A are the same as those in the formula (II). ] And bisphenols represented by the following formula (V): [Where Ar ¹ and Ar ² are the same or different,
It is a phenyl group or a naphthyl group, and these groups may be substituted with at least one selected from the group consisting of a chlorine atom, an alkyl group having 1 to 5 carbon atoms, a methoxycarbonyl group and an ethoxycarbonyl group. ] The diaryl carbonates represented by
) And the compound of formula (IV) above,
5-95 mol% of the compound of the above formula (III) and the above formula (IV)
The compound of formula (V) is used in an amount of 95 to 5 mol%, and the compound of formula (V) is added in an amount of 1.0 to 1.3 mol per 1 mol of the total amount of the compound of formula (III) and the compound of formula (IV). It is used in a ratio to cause melt polycondensation and has a reduced viscosity of at least 0.3.
A method for producing a polycarbonate copolymer, which comprises producing a polycarbonate having a dl / g. 3. An information transmission medium comprising the polycarbonate copolymer according to claim 1 as a material. 4. An information recording medium made of the polycarbonate copolymer according to claim 1.