JP2025119165A - Polycarbonate resin and optical member using said resin - Google Patents

Abstract

To provide a polycarbonate resin that achieves a high Abbe number while exhibiting small orientation birefringence and photoelastic coefficient.SOLUTION: A polycarbonate resin includes a repeating unit represented by formula (1) and/or formula (2), a repeating unit represented by a spirofluorene, and a repeating unit represented by bisphenol TMC, wherein the polycarbonate resin has a weight-average molecular weight Mw of 10,000 or greater.SELECTED DRAWING: Figure 1

Description

The present invention relates to polycarbonate resins and optical components made from such resins.

Glass, which has traditionally been used as a material for optical systems, is capable of achieving the various optical properties required and has excellent environmental resistance, but it has the problem of being difficult to process. In response to this, resin, which is cheaper than glass materials and has excellent processability, has come to be used for optical components.

In the optical design of optical units, it is known to correct chromatic aberration by combining multiple lenses with different Abbe numbers. For example, chromatic aberration can be corrected by combining a lens made of an alicyclic polyolefin resin, which has a low refractive index and a high Abbe number, with a lens made of a polycarbonate resin (nd = 1.59, νd = 31) made from bisphenol A, which has a high refractive index and a low Abbe number. In recent years, there has been active development of resins with high refractive indexes and low Abbe numbers, and as a result, demand for resins with high Abbe numbers has also increased. For example, Patent Document 1 describes a polycarbonate resin with a high Abbe number and a low photoelastic coefficient, which is produced by copolymerizing bisphenol A with pentacyclopentadecanedimethanol (hereinafter sometimes abbreviated as PCPDM). Patent Document 2 proposes a method for producing carbonate derivatives without using a base by photoreacting halogenated methane with a specific amount of a hydroxyl group-containing compound in the presence of oxygen. One example of this method is a polycarbonate copolymer of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (hereinafter sometimes abbreviated as BPEF) and PCPDM. Patent Documents 3 and 4 describe a polycarbonate resin with a high refractive index and low orientation birefringence, produced by copolymerizing BPEF with 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro(5,5)undecane (hereinafter sometimes abbreviated as SPG) and 4,4'-(3,3,5-trimethylcyclohexylidene)bisphenol (hereinafter sometimes abbreviated as BisTMC).

Japanese Patent Application Laid-Open No. 2000-302860 WO2020/100977 WO2019/188702 WO2022/004239

However, the polycarbonate resin made from the above-mentioned bisphenol A and PCPDM had issues, such as room for improvement in its photoelastic coefficient and high orientation birefringence. Furthermore, the resulting resin had a high molecular weight, making it unsuitable for injection molding applications and unable to be used for thin optical components such as imaging lenses. Furthermore, the above-mentioned BPEF and PCPDM copolymer polycarbonate had an extremely low weight-average molecular weight of 3,360, making it insufficient for use as a structural or optical material. Furthermore, polycarbonate resin made from BPEF, SPG, and BisTMC had issues, such as a low Abbe number relative to its refractive index, and there was also room for improvement in its photoelastic coefficient.

The object of the present invention is to provide a polycarbonate resin that has a high Abbe number relative to its refractive index, and also has low orientation birefringence and photoelastic coefficient.

The present inventors have found that the above problems can be solved by the present invention having the following aspects.
That is, the present invention is as follows.

<<Aspect 1>>
A polycarbonate resin comprising a repeating unit represented by formula (1) and/or formula (2), a repeating unit represented by formula (3), and a repeating unit represented by formula (4), wherein the total amount of the repeating units represented by formula (1) and/or formula (2) in all repeating units of the resin is 50 mol % or more, and the polycarbonate resin has a weight average molecular weight Mw of 10,000 or more.

(In the formula, R ¹ to R ⁴ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.)
(In formula (4), n is a number ranging from 0 to 8, and each R represents an alkyl group having 1 to 3 carbon atoms.)

Aspect 2
2. The polycarbonate resin according to claim 1, having a weight average molecular weight Mw of 10,000 or more and 60,000 or less.
Aspect 3
3. The polycarbonate resin according to claim 1, wherein the repeating unit represented by formula (3) accounts for more than 0 mol % and not more than 50 mol % of all repeating units in the resin.
Aspect 4
Aspect 4. The polycarbonate resin according to any one of Aspects 1 to 3, wherein the repeating unit of formula (4) accounts for more than 0 mol % and not more than 40 mol % of all repeating units of the resin.
Aspect 5
Aspects 5. The polycarbonate resin according to any one of Aspects 1 to 4, wherein R ¹ to R ⁴ in formula (3) are hydrogen atoms.
Aspect 6
Aspect 6. The polycarbonate resin according to any one of Aspects 1 to 5, wherein the repeating unit of formula (4) is a repeating unit derived from bisphenol TMC.
Aspect 7
Aspect 7. The polycarbonate resin according to any one of Aspects 1 to 6, wherein the absolute value of orientation birefringence is 10.0 × 10 ⁻³ or less.
Aspect 8
Aspect 8. The polycarbonate resin of any one of aspects 1 to 7, having a photoelastic coefficient of less than 25×10 ⁻¹² Pa.
Aspect 9
Aspect 9. The polycarbonate resin according to any one of aspects 1 to 8, having an Abbe number of 25.0 or more.
Aspect 10
An optical member made of the polycarbonate resin according to any one of Aspects 1 to 9.
Aspect 11
11. The optical member according to aspect 10, wherein the optical member is an imaging lens.

The polycarbonate resin of the present invention has a high Abbe number and small orientation birefringence and photoelastic coefficient, making it particularly effective in industry.

FIG. 1 shows the relationship between the refractive index and the Abbe number of the thermoplastic resin of the present invention and a conventional resin.

The present invention will now be described in more detail.

<Polycarbonate resin>
The polycarbonate resin of the present invention is a polycarbonate resin containing repeating units represented by formula (1) and/or formula (2), repeating units represented by formula (3), and repeating units represented by formula (4), and the total content of repeating units represented by formula (1) and/or formula (2) among all repeating units of the resin is 50 mol % or more.

In the above definition of mol%, the total of repeating units represented by formula (1) and/or formula (2) refers to the total of units of formula (1) and formula (2) when the polycarbonate resin contains units represented by formula (1) and formula (2), and refers to either unit represented by formula (1) or formula (2) when the polycarbonate resin contains either unit represented by formula (1) or formula (2).

(In the formula, R ¹ to R ⁴ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.)

(In formula (4), n is a number ranging from 0 to 8, and each R represents an alkyl group having 1 to 3 carbon atoms.)

The polycarbonate resin of the present invention has a weight-average molecular weight Mw of 10,000 or more, preferably 15,000 or more, and more preferably 20,000 or more. A weight-average molecular weight Mw of 10,000 or more is preferable because it has sufficient mechanical strength for use as a structural material or optical material. Furthermore, the weight-average molecular weight Mw is preferably 60,000 or less, more preferably 55,000 or less, even more preferably 50,000 or less, and even more preferably 45,000 or less. A weight-average molecular weight Mw of 60,000 or less is preferable because it provides excellent fluidity during injection molding. This is particularly preferable because it provides excellent fluidity when the polycarbonate resin of the present invention is used for thin-walled optical components such as imaging lenses. The weight-average molecular weight Mw can be measured by GPC using polystyrene of known molecular weight as a standard sample and chloroform as a developing solvent.

The polycarbonate resin of the present invention preferably has an absolute value of orientation birefringence of 10.0 × 10 ⁻³ or less, more preferably 9.0 × 10 ⁻³ or less, even more preferably 8.0 × 10 ⁻³ or less, even more preferably 7.0 × 10 ⁻³ or less, particularly preferably 6.0 × 10 ⁻³ or less, even more preferably 5.0 × 10 ⁻³ or less, and most preferably 4.0 × 10 ⁻³ or less. An absolute value of orientation birefringence of less than the above range is preferable because birefringence due to molecular orientation is less likely to occur. Orientation birefringence can be measured at a wavelength of 589 nm by cutting a test piece 70 mm long (45 mm between chucks) and 15 mm wide from a 100 μm thick cast film obtained from the polycarbonate resin, stretching it twice at Tg + 10 ° C.

The polycarbonate resin of the present invention preferably has a photoelastic coefficient of less than 25×10 ⁻¹² Pa, more preferably 20×10 ⁻¹² Pa or less, even more preferably 16×10 ⁻¹² Pa or less, and even more preferably 12×10 ⁻¹² Pa or less. A photoelastic coefficient within the above range is preferred because stress-induced birefringence is less likely to occur. The photoelastic coefficient is measured by cutting a test piece 50 mm long and 10 mm wide from a 100 μm thick cast film obtained from the polycarbonate resin and using a Spectroellipsometer M-220 manufactured by JASCO Corporation.

The polycarbonate resin of the present invention preferably has a refractive index nd measured at a temperature of 20°C and a wavelength of 587.56 nm of 1.540 or more, more preferably 1.550 or more, even more preferably 1.560 or more, even more preferably 1.570 or more, and particularly preferably 1.575 or more. A refractive index of at least the above range is preferred because it allows optical components to be made thinner. The refractive index nd may also be 1.610 or less, 1.600 or less, 1.590 or less, or 1.580 or less. A refractive index nd within the above range is preferred because it increases the degree of freedom in optical design when combining and using multiple lenses.

The polycarbonate resin of the present invention preferably has an Abbe number of 25.0 or more, more preferably 30.0 or more, even more preferably 32.0 or more, even more preferably 37.0 or more, particularly preferably 42.0 or more, and most preferably 46.0 or more. An Abbe number of at least the above ranges is preferred because it reduces chromatic aberration of the optical element. The Abbe number may also be 57.0 or less, 55.0 or less, 50.0 or less, or 47.0 or less. An Abbe number within the above range is preferred because it increases the degree of freedom in optical design when combining and using multiple lenses.

Here, the Abbe number (νd) is calculated using the following formula from the refractive index at a temperature of 20° C. and wavelengths of 486.13 nm, 587.56 nm, and 656.27 nm.
νd=(nd-1)/(nF-nC)
nd: refractive index at a wavelength of 587.56 nm,
nF: refractive index at a wavelength of 486.13 nm,
nC: refers to the refractive index at a wavelength of 656.27 nm.

The refractive index and Abbe number of the polycarbonate resin of the present invention preferably satisfy the following mathematical formula (A).
nd≧−0.0063×νd+α (A)
In formula (A), α is preferably 1.767 or more, more preferably 1.770 or more, even more preferably 1.773 or more, still more preferably 1.776 or more, and most preferably 1.779 or more.
It is preferable that nd>1.535.

The refractive index and Abbe number of the polycarbonate resin of the present invention may satisfy the following mathematical formula (B).
nd≦-0.0023×νd+β (B)
In formula (B), β may be 1.675 or less, 1.673 or less, 1.671 or less, 1.669 or less, or 1.666 or less. When the refractive index and Abbe number are within the above ranges, the Abbe number relative to the refractive index is high, which is preferable since it broadens the scope of optical design.

The polycarbonate resin of the present invention preferably has a glass transition temperature of 130°C or higher, more preferably 133°C or higher, and even more preferably 136°C or higher. A glass transition temperature within the above range is preferred because it broadens the temperature range in which optical components can be used. The glass transition temperature may also be 155°C or lower, 150°C or lower, 145°C or lower, or 140°C or lower. A glass transition temperature within the above range is preferred because it provides an excellent balance between heat resistance and moldability.

The polycarbonate resin of the present invention preferably has a thermal decomposition temperature of 370°C or higher, and more preferably 374°C or higher. Thermal decomposition temperatures above this level are preferred because they provide excellent processing stability when molding the polycarbonate resin of the present invention and also result in less discoloration. The thermal decomposition temperature may also be 420°C or lower, or 400°C or lower. The thermal decomposition temperature can be measured by TGA (thermogravimetric analysis) and is the temperature at which the weight decreases by 5%.

The specific viscosity of the polycarbonate resin of the present invention is preferably 0.12 to 0.32, and more preferably 0.18 to 0.30. A specific viscosity within the above range provides an excellent balance between moldability and strength.

The specific viscosity is measured by measuring the specific viscosity (ηSP) at 20° C. of a solution prepared by dissolving 0.7 g of polycarbonate resin in 100 ml of methylene chloride using an Ostwald viscometer, and calculating the specific viscosity from the following formula:
ηSP=(t-t0)/t0
[t0 is the number of seconds it takes for methylene chloride to fall, and t is the number of seconds it takes for the sample solution to fall]

The partial dispersion ratio (θgF) from the g-line to the F-line of the polycarbonate resin of the present invention is preferably 0.62 or less, more preferably 0.61 or less, even more preferably 0.60 or less, even more preferably 0.59 or less, and most preferably 0.58 or less. A θgF of the above or less is preferred because it broadens the scope of optical design.

Here, the partial dispersion ratio (θgF) from the g-line to the F-line is calculated using the following formula from the refractive indexes at a temperature of 20° C. and wavelengths of 435.83 nm, 587.56 nm, and 656.27 nm.
θgF=(ng-nF)/(nF-nC)
ng: refractive index at a wavelength of 435.83 nm,
nF: refractive index at a wavelength of 486.13 nm,
nC: refers to the refractive index at a wavelength of 656.27 nm.

In the polycarbonate resin of the present invention, R ¹ to R ⁴ in the above formula (3) each independently represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and examples of the hydrocarbon group include an alkyl group, a cycloalkyl group, and an aryl group.

Examples of alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, and t-butyl groups, with methyl and ethyl groups being preferred.

Cycloalkyl groups include cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, and bicyclo[1.1.1]pentanyl groups.

Aryl groups include phenyl, tolyl, naphthyl, and xylyl groups, with phenyl being preferred.

R ¹ to R ⁴ are each independently preferably a hydrogen atom, a methyl group, or a phenyl group, more preferably a hydrogen atom or a phenyl group, and it is further preferred that R ¹ and R ² are each independently a hydrogen atom or a phenyl group, and R ³ and R ⁴ are each independently a hydrogen atom, since this increases the volume of the aliphatic ring in space and reduces the photoelastic coefficient.

In the above formula (4), n is in the range of 0 to 8, preferably 0 to 5 or 1 to 3, and is particularly preferably 3, as this results in a high glass transition temperature.

R is selected from alkyl groups having 1 to 3 carbon atoms, preferably a methyl group or an ethyl group, and is particularly preferred when it is a methyl group, as it has a high glass transition temperature.

In particular, the repeating unit of the above formula (4) is preferably a repeating unit derived from 4,4'-(3,3,5-trimethylcyclohexylidene)bisphenol (also known as bisphenol TMC), 4,4'-cyclohexylidenebisphenol (also known as bisphenol Z), or 4,4'-(3-methylcyclohexylidene)bisphenol (also known as bisphenol 3MZ), and among these, a repeating unit derived from bisphenol TMC is preferred because it can increase the glass transition temperature.

The repeating units represented by the above formula (1) and/or formula (2) are repeating units derived from pentacyclopentadecanedimethanol, and the above formula (1) and/or formula (2) may be pure substances or mixtures of the individual isomers in any ratio. Pentacyclopentadecanedimethanol includes the following structural formulas:

The repeating unit represented by the above formula (3) is preferably a repeating unit derived from 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene or 9,9-bis[4-(2-hydroxyethoxy)-3-phenylphenyl]fluorene, and a repeating unit derived from 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene is more preferred because it has low orientation birefringence and photoelastic coefficient.

The polycarbonate resin of the present invention may contain repeating units other than those represented by the above formulas (1) to (4) as long as the advantageous effects of the present invention are obtained. Examples of dihydroxy compounds that provide such repeating units include ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, tricyclo[5.2.1.0 ^2,6 ]decanedimethanol, cyclohexane-1,4-dimethanol, decalin-2,6-dimethanol, norbornane dimethanol, cyclopentane-1,3-dimethanol, isosorbide, isomannide, isoidide, hydroquinone, resorcinol, 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(3-methyl-4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane, bis(4-hydroxyphenyl)diphenylmethane, 1,3-bis(2-(4-hydroxyphenyl)propane), 1,3-bis(4-hydroxyphenyl)diphenylmethane, ... Examples of such repeating units include 4,4'-(4-hydroxyphenyl)-2-propyl)benzene, 4,4'-(3,3,5-trimethylcyclohexylidene)bisphenol, 4,4'-cyclohexylidenebisphenol, 4,4'-(3-methylcyclohexylidene)bisphenol, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfide, biphenol, bisphenolfluorene, biscresolfluorene, 1,1'-bi-2-naphthol, and 2,2'-bis(2-hydroxyethoxy)-1,1'-binaphthalene. Such repeating units may account for 30 mol % or less of all repeating units.

In the polycarbonate resin of the present invention, the total amount of repeating units represented by the above formulas (1) to (4) is preferably 70 mol % or more, more preferably 80 mol % or more, and even more preferably 90 mol % or more, of all repeating units.

The total amount of repeating units represented by the above formula (1) and/or formula (2) among all repeating units of the resin is 50 mol% or more, preferably 55 mol% or more, and even more preferably 60 mol% or more, as this results in a high Abbe number.

The repeating units represented by formula (3) above may account for more than 0 mol%, 2 mol% or more, 8 mol% or more, 12 mol% or more, 15 mol% or more, 20 mol% or more, 25 mol% or more, 30 mol% or more, 33 mol% or more, or 37 mol% or more, or may be 50 mol% or less, 45 mol% or less, 38 mol% or less, 25 mol% or less, 16 mol% or less, or 10 mol% or less of all repeating units in the resin. The repeating units are preferably more than 0 mol% and 50 mol% or less, more preferably 2 to 45 mol%, and even more preferably 2 to 40 mol% since orientation birefringence is low.

Of all the repeating units in the resin, the repeating units represented by formula (4) may be greater than 0 mol%, 2 mol% or more, 3 mol% or more, 5 mol% or more, 8 mol% or more, 10 mol% or more, 15 mol% or more, 20 mol% or more, or 25 mol% or more, or may be 40 mol% or less, 35 mol% or less, 30 mol% or less, 25 mol% or less, or 20 mol% or less. The repeating units are preferably greater than 0 mol% and 40 mol% or less, more preferably 2 to 35 mol%, and even more preferably 3 to 30 mol% due to the high glass transition temperature.

The polycarbonate resin of the present invention preferably does not have terminal phenolic hydroxyl groups. That is, when a monomer that produces the repeating unit represented by formula (4) above is polymerized and bonded to the terminal, the terminal group becomes a phenolic hydroxyl group. Therefore, it is preferable to reduce the amount of terminal phenolic hydroxyl groups in the polycarbonate resin by using an excess amount of carbonate diester during polymerization compared to the dihydroxy compound raw material, thereby converting the terminal to a phenyl group.

The ratio of terminal phenolic hydroxyl groups can be determined as follows.
Terminal phenolic hydroxyl group ratio=(amount of terminal phenolic hydroxyl groups/total amount of terminals)×100
All of the terminals consist of a terminal phenolic hydroxyl group, a terminal alcoholic hydroxyl group, and a terminal phenyl group.
Although not limited to this example, specifically, the terminal phenolic hydroxyl group ratio can be determined by the following method.

(1) The terminal phenolic hydroxyl groups are observed by ¹ H NMR measurement of the polycarbonate resin, and the integral of the corresponding peak is taken and set to 1. At the same time, the integral intensity (A) of one proton of the fluorene structure is calculated from the integral intensities of the peaks at positions 4 and 5 of the fluorene structure derived from the above formula (3). When no peak of the terminal phenolic hydroxyl groups is observed, the terminal phenolic hydroxyl group ratio is 0.

(2) The average degree of polymerization of the polycarbonate resin is determined from the average molecular weight obtained by GPC measurement of the polycarbonate resin and the molecular weight and molar ratio of each repeating unit, and the integrated intensity (B) in the ¹ H NMR spectrum of the terminal is calculated using the following formula from the mol % and integrated intensity (A) of the above formula (3).
(B) = (A) × 100 × 2 / ([mol % of the above formula (3)] × average degree of polymerization)

(3) The terminal phenolic hydroxyl group ratio is calculated as 1/(B) × 100.

The ratio of terminal phenolic hydroxyl groups to all terminals of the polycarbonate resin of the present invention is preferably 30% or less, 20% or less, 15% or less, 10% or less, 5% or less, 3% or less, 1% or less, or 0.5% or less, which is preferable because it suppresses color change due to wet heat.

The polycarbonate resin of the present invention preferably has a total light transmittance of 80% or more, more preferably 85% or more, and particularly preferably 88% or more, when molded into a 1 mm thick article. A 1 mm thick molded article can be obtained by subjecting the polycarbonate resin of the present invention to injection molding, hot press molding, melt extrusion molding, or the like.

The saturated water absorption of the polycarbonate resin of the present invention may be 0.10% to 0.70%, 0.20% to 0.70%, or 0.30% to 0.65%.

<Method for producing polycarbonate resin>
The polycarbonate resin of the present invention is produced by a reaction means known per se for producing ordinary polycarbonate resins, for example, a method of reacting a dihydroxy compound with a carbonate precursor such as a carbonic acid diester. The basic means for these production methods will now be briefly described.

Transesterification reactions using a carbonate diester as a carbonate precursor are carried out by heating and stirring a specified proportion of dihydroxy component with the carbonate diester under an inert gas atmosphere, and distilling off the resulting alcohol or phenol. The reaction temperature varies depending on the boiling point of the resulting alcohol or phenol, but is usually in the range of 120 to 300°C. The reaction is completed by reducing the pressure from the beginning and distilling off the resulting alcohol or phenol. If necessary, a terminal capping agent, antioxidant, etc. may also be added.

The carbonate diester used in the transesterification reaction includes esters of optionally substituted aryl groups and aralkyl groups having 6 to 12 carbon atoms. Specific examples include diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl)carbonate, and m-cresyl carbonate. Of these, diphenyl carbonate is particularly preferred. The amount of diphenyl carbonate used is preferably 0.95 to 1.10 mol, more preferably 0.98 to 1.04 mol, per 1 mol of the total dihydroxy compounds.

In addition, in melt polymerization methods, a polymerization catalyst can be used to increase the polymerization rate. Examples of such polymerization catalysts include alkali metal compounds, alkaline earth metal compounds, and nitrogen-containing compounds.

Preferred compounds of this type include organic acid salts, inorganic salts, oxides, hydroxides, hydrides, alkoxides, and quaternary ammonium hydroxides of alkali metals and alkaline earth metals, and these compounds can be used alone or in combination.

Examples of alkali metal compounds include sodium hydroxide, potassium hydroxide, cesium hydroxide, lithium hydroxide, sodium bicarbonate, sodium carbonate, potassium carbonate, cesium carbonate, lithium carbonate, sodium acetate, potassium acetate, cesium acetate, lithium acetate, sodium stearate, potassium stearate, cesium stearate, lithium stearate, sodium borohydride, sodium benzoate, potassium benzoate, cesium benzoate, lithium benzoate, disodium hydrogen phosphate, dipotassium hydrogen phosphate, dilithium hydrogen phosphate, disodium phenylphosphate, disodium, dipotassium, dicesium, and dilithium salts of bisphenol A, and sodium, potassium, cesium, and lithium salts of phenol.

Examples of alkaline earth metal compounds include magnesium hydroxide, calcium hydroxide, strontium hydroxide, barium hydroxide, magnesium carbonate, calcium carbonate, strontium carbonate, barium carbonate, magnesium diacetate, calcium diacetate, strontium diacetate, and barium diacetate.

Examples of nitrogen-containing compounds include quaternary ammonium hydroxides having alkyl or aryl groups, such as tetramethylammonium hydroxide, tetraethylammonium hydroxide, tetrapropylammonium hydroxide, tetrabutylammonium hydroxide, and trimethylbenzylammonium hydroxide. Examples include bases or basic salts such as tetramethylammonium borohydride, tetrabutylammonium borohydride, tetrabutylammonium tetraphenylborate, and tetraphenylammonium tetraphenylborate.

Other transesterification catalysts include salts of zinc, tin, zirconium, lead, titanium, germanium, antimony, and osmium, such as zinc acetate, zinc benzoate, zinc 2-ethylhexanoate, tin(II) chloride, tin(IV) chloride, tin(II) acetate, tin(IV) acetate, dibutyltin dilaurate, dibutyltin oxide, dibutyltin dimethoxide, zirconium acetylacetonate, zirconium oxyacetate, zirconium tetrabutoxide, lead(II) acetate, and lead(IV) titanium tetrabutoxide(IV). The catalysts used in WO 2011/010741 and JP 2017-179323 A may also be used.

A catalyst consisting of aluminum or a compound thereof and a phosphorus compound may also be used. In this case, the amount is preferably 80 μmol to 1000 μmol, more preferably 90 μmol to 800 μmol, and even more preferably 100 μmol to 600 μmol per 1 mol of the dihydroxy component.

Aluminum salts include organic and inorganic aluminum acid salts. Examples of organic aluminum acid salts include aluminum carboxylates, specifically aluminum formate, aluminum acetate, aluminum propionate, aluminum oxalate, aluminum acrylate, aluminum laurate, aluminum stearate, aluminum benzoate, aluminum trichloroacetate, aluminum lactate, aluminum citrate, and aluminum salicylate. Examples of inorganic aluminum acid salts include aluminum chloride, aluminum hydroxide, aluminum hydroxide chloride, aluminum carbonate, aluminum phosphate, and aluminum phosphonate. Examples of aluminum chelate compounds include aluminum acetylacetonate, aluminum acetylacetate, aluminum ethylacetoacetate, and aluminum ethylacetoacetate diisopropoxide.

Examples of phosphorus compounds include phosphonic acid compounds, phosphinic acid compounds, phosphine oxide compounds, phosphonous acid compounds, phosphineous acid compounds, and phosphine compounds. Among these, phosphonic acid compounds, phosphinic acid compounds, and phosphine oxide compounds are particularly preferred, with phosphonic acid compounds being particularly preferred.

The amount of these polymerization catalysts used is preferably 0.1 μmol to 500 μmol, more preferably 0.5 μmol to 300 μmol, and even more preferably 1 μmol to 100 μmol per 1 mol of the dihydroxy component.

A catalyst deactivator can also be added in the latter stages of the reaction. Known catalyst deactivators are effectively used, but among these, ammonium salts and phosphonium salts of sulfonic acid are preferred. Salts of dodecylbenzenesulfonic acid, such as tetrabutylphosphonium dodecylbenzenesulfonate, and salts of paratoluenesulfonic acid, such as tetrabutylammonium paratoluenesulfonate, are even more preferred.

Preferably used sulfonic acid esters include methyl benzenesulfonate, ethyl benzenesulfonate, butyl benzenesulfonate, octyl benzenesulfonate, phenyl benzenesulfonate, methyl paratoluenesulfonate, ethyl paratoluenesulfonate, butyl paratoluenesulfonate, octyl paratoluenesulfonate, and phenyl paratoluenesulfonate. Among these, tetrabutylphosphonium dodecylbenzenesulfonate is most preferably used.

When at least one polymerization catalyst selected from alkali metal compounds and/or alkaline earth metal compounds is used, the amount of these catalyst deactivators used is preferably 0.5 to 50 mol, more preferably 0.5 to 10 mol, and even more preferably 0.8 to 5 mol per mol of the catalyst.

<Optional Additives>
The polycarbonate resin of the present invention can be used as a resin composition by appropriately adding additives such as a mold release agent, a heat stabilizer (sometimes also referred to as an antioxidant), an ultraviolet absorber, a bluing agent, an antistatic agent, a flame retardant, a plasticizer, a filler, an antioxidant, a light stabilizer, a polymerized metal deactivator, a lubricant, a surfactant, an antibacterial agent, etc. Specific examples of the mold release agent and heat stabilizer include those described in WO 2011/010741.

Particularly preferred release agents include stearic acid monoglyceride, stearic acid triglyceride, pentaerythritol tetrastearate, and a mixture of stearic acid triglyceride and stearyl stearate. Furthermore, the amount of the ester in the release agent is preferably 90% by weight or more, and more preferably 95% by weight or more, based on 100% by weight of the release agent. Furthermore, the content of the release agent is preferably in the range of 0.005 to 2.0 parts by weight, more preferably 0.01 to 0.6 parts by weight, and even more preferably 0.02 to 0.5 parts by weight, per 100 parts by weight of polycarbonate resin.

Heat stabilizers include phosphorus-based heat stabilizers, sulfur-based heat stabilizers, and hindered phenol-based heat stabilizers.

Particularly preferred phosphorus-based heat stabilizers include tris(2,4-di-tert-butylphenyl)phosphite, bis(2,6-di-tert-butyl-4-methylphenyl)pentaerythritol diphosphite, tetrakis(2,4-di-tert-butylphenyl)-4,4'-biphenylene diphosphonite, distearylpentaerythritol diphosphite, bis(2,4-dicumylphenyl)pentaerythritol diphosphite, cyclic neopentanetetraylbis(2,6-di-tert-butyl-4-methylphenyl phosphite), and bis(2,4-di-tert-butylphenyl)pentaerythritol diphosphite. The content of the phosphorus-based heat stabilizer is preferably 0.001 to 0.2 parts by weight per 100 parts by weight of polycarbonate resin.

A particularly preferred sulfur-based heat stabilizer is pentaerythritol-tetrakis(3-laurylthiopropionate). The content of the sulfur-based heat stabilizer is preferably 0.001 to 0.2 parts by weight per 100 parts by weight of polycarbonate resin.

Preferred hindered phenol-based heat stabilizers include octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, pentaerythritol-tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], triethylene glycol-bis[3-(3-tert-butyl-5-methyl-4-hydroxyphenyl)propionate], 1,6-hexanediol-bis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-trimethyl-2,4,6-tris(3 ,5-di-tert-butyl-4-hydroxybenzyl)benzene, N,N-hexamethylenebis(3,5-di-tert-butyl-4-hydroxy-hydrocinnamide), 3,5-di-tert-butyl-4-hydroxy-benzylphosphonate-diethyl ester, tris(3,5-di-tert-butyl-4-hydroxybenzyl)isocyanurate, 3,9-bis{1,1-dimethyl-2-[β-(3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]ethyl}-2,4,8,10-tetraoxaspiro(5,5)undecane.

The content of the hindered phenol-based heat stabilizer is preferably 0.001 to 0.3 parts by weight per 100 parts by weight of polycarbonate resin.

Phosphorus-based heat stabilizers and hindered phenol-based heat stabilizers can also be used in combination.

Preferably, the ultraviolet absorber is at least one ultraviolet absorber selected from the group consisting of benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, triazine-based ultraviolet absorbers, cyclic iminoester-based ultraviolet absorbers, and cyanoacrylate-based ultraviolet absorbers.

Of the benzotriazole-based ultraviolet absorbers, 2-(2-hydroxy-5-tert-octylphenyl)benzotriazole and 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazol-2-yl)phenol] are more preferred.

Examples of benzophenone-based ultraviolet absorbers include 2-hydroxy-4-n-dodecyloxybenzophenone and 2-hydroxy-4-methoxy-2'-carboxybenzophenone.

Examples of triazine-based ultraviolet absorbers include 2-(4,6-diphenyl-1,3,5-triazin-2-yl)-5-[(hexyl)oxy]-phenol and 2-(4,6-bis(2.4-dimethylphenyl)-1,3,5-triazin-2-yl)-5-[(octyl)oxy]-phenol.

2,2'-p-phenylenebis(3,1-benzoxazin-4-one) is particularly suitable as a cyclic imino ester UV absorber.

Cyanoacrylate-based UV absorbers include 1,3-bis-[(2'-cyano-3',3'-diphenylacryloyl)oxy]-2,2-bis[(2-cyano-3,3-diphenylacryloyl)oxy]methyl)propane and 1,3-bis-[(2-cyano-3,3-diphenylacryloyl)oxy]benzene.

The amount of UV absorber to be added is preferably 0.01 to 3.0 parts by weight per 100 parts by weight of polycarbonate resin. This amount range makes it possible to impart sufficient weather resistance to molded polycarbonate resin products depending on the application.

<Optical components>
The optical member of the present invention contains the polycarbonate resin described above. Such optical members are not particularly limited as long as they are used for optical applications in which the polycarbonate resin is useful, and examples of such optical members include optical disks, transparent conductive substrates, optical cards, sheets, films, optical fibers, lenses, prisms, optical films, substrates, optical filters, and hard coat films.

The optical component of the present invention may also be composed of a resin composition containing the above-mentioned polycarbonate resin, and the resin composition may contain additives such as heat stabilizers, plasticizers, light stabilizers, polymerized metal deactivators, flame retardants, lubricants, antistatic agents, surfactants, antibacterial agents, UV absorbers, mold release agents, bluing agents, fillers, and antioxidants, as needed.

<Optical lenses>
The optical member of the present invention can be particularly an optical lens. Examples of such an optical lens include imaging lenses for mobile phones, smartphones, tablet terminals, personal computers, digital cameras, video cameras, vehicle-mounted cameras, surveillance cameras, etc., and sensing cameras such as TOF cameras. The optical member of the present invention is particularly useful as an imaging lens.

When the optical lens of the present invention is manufactured by injection molding, molding is preferably carried out under conditions of a cylinder temperature of 220 to 350°C and a mold temperature of 70 to 180°C. More preferably, molding is carried out under conditions of a cylinder temperature of 240 to 300°C and a mold temperature of 80 to 170°C. If the cylinder temperature is higher than 350°C, the polycarbonate resin will decompose and discolor, and if it is lower than 230°C, the melt viscosity will be high, making molding difficult. Furthermore, if the mold temperature is higher than 180°C, it will be difficult to remove a molded piece made of polycarbonate resin from the mold. On the other hand, if the mold temperature is lower than 70°C, the resin will harden too quickly in the mold during molding, making it difficult to control the shape of the molded piece and making it difficult to fully transfer the shape applied to the mold.

The optical lens of the present invention is preferably implemented in the form of an aspherical lens, if necessary. Because a single aspherical lens can eliminate spherical aberration, there is no need to combine multiple spherical lenses to eliminate spherical aberration, which allows for weight reduction and reduced molding costs. Therefore, aspherical lenses are particularly useful as camera lenses, among other optical lenses.

Furthermore, because the polycarbonate resin of the present invention has high molding fluidity, it is particularly useful as a material for optical lenses that are thin, small, and have complex shapes. Specific lens sizes include a central thickness of 0.05 to 3.0 mm, more preferably 0.05 to 2.0 mm, and even more preferably 0.1 to 2.0 mm. Furthermore, the diameter is 1.0 mm to 20.0 mm, more preferably 1.0 to 10.0 mm, and even more preferably 3.0 to 10.0 mm. Furthermore, the lens preferably has a meniscus shape, with one side convex and the other concave.

Lenses made from the polycarbonate resin of the present invention can be formed by any method, including mold molding, cutting, polishing, laser processing, electrical discharge processing, and etching. Of these, mold molding is more preferred in terms of production costs.

The present invention will be further explained in detail in the following examples, but the present invention is not limited thereto.

The evaluation was carried out by the following method.
<Copolymerization ratio of polycarbonate resin>
The copolymerization ratio of each polycarbonate resin was calculated by measuring ¹ H NMR using a JEOL JNM-ECZ400S.

<Weight average molecular weight (Mw)
The weight average molecular weight Mw was measured using EcoSEC HLC-8320GPC manufactured by TOSOH under the conditions described below.
Detector: UV-8420, solvent: chloroform, column: TOSOH TSKgel SupermultiporeHZM-M × 3 + TSKgel guard column (4.6 × 200 nm), measurement temperature: 40°C, flow rate: 0.35 ml/min, injection amount: 5 μl, sample concentration: 1 mg/5 ml, standard sample: TSKstandard Polystyrene

<Refractive index>
A 3 mm thick test piece of each polycarbonate resin was prepared and polished, and then the refractive index nd (587.56 nm) was measured using a Kalnew Precision Refractometer KPR-2000 manufactured by Shimadzu Corporation.

<Abbe number>
The Abbe number (νd) was calculated using the following formula from the refractive index at a temperature of 20° C. and wavelengths of 486.13 nm, 587.56 nm, and 656.27 nm.
νd=(nd-1)/(nF-nC)
nd: refractive index at a wavelength of 587.56 nm,
nF: refractive index at a wavelength of 486.13 nm,
nC: refers to the refractive index at a wavelength of 656.27 nm.

<Absolute value of orientation birefringence (|Δn|)>
Polycarbonate resin was dissolved in methylene chloride, cast onto a glass dish, and thoroughly dried to prepare a 100 μm thick cast film. A 70 mm long (45 mm between chucks) and 15 mm wide test piece was cut out from the film and stretched twice at Tg+10°C. The retardation (Re) at 589 nm was measured using an Ellipsometer M-220 manufactured by JASCO Corporation, and the absolute value of orientation birefringence (|Δn|) was calculated using the following formula:
|Δn|=|Re/d|
Δn: Orientation birefringence Re: Phase difference (nm)
d: thickness (nm)

<Photoelastic coefficient>
Polycarbonate resin was dissolved in methylene chloride, cast onto a glass dish, and thoroughly dried to prepare a cast film with a thickness of 100 μm. Test pieces with a length of 50 mm and a width of 10 mm were cut out from the film, and the photoelastic coefficient was measured using an Ellipsometer M-220 manufactured by JASCO Corporation.

<Glass transition temperature (Tg)>
The obtained polycarbonate resin was measured at a temperature rising rate of 20°C/min using a Discovery DSC 25Auto model manufactured by TA Instruments Japan Co., Ltd. The measurement was carried out using a sample of 5 to 10 mg.

<Thermal decomposition temperature (Td-5)>
The polycarbonate resin thus obtained was measured at a temperature increase rate of 20°C/min using an SDT650 manufactured by TA Instruments Japan Co., Ltd., and the temperature at which the weight was reduced by 5% was determined based on the weight at 50°C. The sample used for the measurement was 3 to 4 mg.

<θgF>
The partial dispersion ratio (θgF) from the g-line to the F-line is calculated using the following formula from the refractive indexes at a temperature of 20° C. and wavelengths of 435.83 nm, 587.56 nm, and 656.27 nm.
θgF=(ng-nF)/(nF-nC)
ng: refractive index at a wavelength of 435.83 nm,
nF: refractive index at a wavelength of 486.13 nm,
nC: refers to the refractive index at a wavelength of 656.27 nm.

<Ratio of terminal phenolic hydroxyl groups>
The ratio of terminal phenolic hydroxyl groups can be determined as follows.
Terminal phenolic hydroxyl group ratio=(amount of terminal phenolic hydroxyl groups/total amount of terminals)×100
Specifically, the terminal phenolic hydroxyl group ratio can be determined by the following method.

(1) The terminal phenolic hydroxyl groups are observed by ¹ H NMR measurement of the polycarbonate resin, and the integral of the corresponding peak is taken and set to 1. At the same time, the integral intensity (A) of one proton of the fluorene structure is calculated from the integral intensities of the peaks at positions 4 and 5 of the fluorene structure derived from the above formula (3). When no peak of the terminal phenolic hydroxyl groups is observed, the terminal phenolic hydroxyl group ratio is 0.

(2) The average degree of polymerization of the polycarbonate resin is determined from the average molecular weight obtained by GPC measurement of the polycarbonate resin and the molecular weight and molar ratio of each repeating unit, and the integrated intensity (B) in the ¹ H NMR spectrum of the terminal is calculated using the following formula from the mol % and integrated intensity (A) of the above formula (3).
(B) = (A) × 100 × 2 / ([mol % of the above formula (3)] × average degree of polymerization)

(3) The terminal phenolic hydroxyl group ratio is calculated as 1/(B) × 100.

Example 1
3.51 g (0.01 mol) of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (hereinafter sometimes abbreviated as BPEF), 97.61 g (0.37 mol) of pentacyclopentadecanedimethanol (hereinafter sometimes abbreviated as PCPDM), 6.2 g (0.02 mol) of 4,4'-(3,3,5-trimethylcyclohexylidene)bisphenol (hereinafter sometimes abbreviated as "BisTMC"), 89.12 g (0.42 mol) of diphenyl carbonate, and 17 μL of a 60 mmol/L aqueous sodium hydrogen carbonate solution (1 μmol of sodium hydrogen carbonate) and 22 μL of a 274 mmol/L aqueous tetramethylammonium hydroxide solution (6 μmol of tetramethylammonium hydroxide) as catalysts were heated to 180 ° C. under a nitrogen atmosphere and melted. The reactor internal pressure was then reduced to 20 kPa over 40 minutes, while the temperature was raised to 250°C at a rate of 60°C/hr. After 70% of the theoretical amount of phenol had been distilled off, the reactor internal pressure was reduced to 133 Pa or less over 1 hour. The reaction was then terminated by stirring at 260°C for 40 minutes at a reactor internal pressure of 133 Pa or less, and the resin was removed. The copolymerization ratio of BPEF, PCPDM, and BisTMC in the resulting polycarbonate resin was measured by ^1H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientational birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated. The terminal phenolic hydroxyl group ratio of the polycarbonate resin was 0%.

Example 2
A polycarbonate resin was produced in the same manner as in Example 1, except that the amount of BPEF charged was 22.80 g (0.5 mol) and the amount of PCPDM charged was 86.06 g (0.33 mol). The copolymerization ratio of the resulting polycarbonate resin derived from BPEF, PCPDM, and BisTMC was measured by ¹ H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated. The terminal phenolic hydroxyl group ratio of the polycarbonate resin was 0%.

Example 3
A polycarbonate resin was produced in the same manner as in Example 1, except that the amount of BPEF charged was 31.57 g (0.07 mol) and the amount of PCPDM charged was 80.82 g (0.31 mol). The copolymerization ratio of the resulting polycarbonate resin derived from BPEF, PCPDM, and BisTMC was measured by ¹ H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated. The terminal phenolic hydroxyl group ratio of the polycarbonate resin was 0%.

Example 4
A polycarbonate resin was produced in the same manner as in Example 1, except that the amount of BPEF charged was 61.39 g (0.14 mol) and the amount of PCPDM charged was 62.97 g (0.24 mol). The copolymerization ratio of the resulting polycarbonate resin derived from BPEF, PCPDM, and BisTMC was measured by ¹ H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated. The terminal phenolic hydroxyl group ratio of the polycarbonate resin was 0%.

Example 5
A polycarbonate resin was produced in the same manner as in Example 1, except that the amount of BPEF charged was 70.16 g (0.16 mol), the amount of PCPDM charged was 52.48 g (0.2 mol), and the amount of BisTMC charged was 12.40 g (0.04 mol). The copolymerization ratio of the resulting polycarbonate resin derived from BPEF, PCPDM, and BisTMC was measured by ¹ H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated. The terminal phenolic hydroxyl group ratio of the polycarbonate resin was 0%.

Example 6
A polycarbonate resin was produced in the same manner as in Example 1, except that the amount of BPEF charged was 17.54 g (0.04 mol), the amount of PCPDM charged was 62.97 g (0.24 mol), and the amount of BisTMC charged was 37.2 g (0.12 mol). The copolymerization ratio of the resulting polycarbonate resin derived from BPEF, PCPDM, and BisTMC was measured by ¹ H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated. The terminal phenolic hydroxyl group ratio of the polycarbonate resin was 0%.

<Comparative Example 1>
45.66 g (0.20 mol) of bisphenol A (hereinafter sometimes abbreviated as BPA), 52.48 g (0.20 mol) of PCPDM, 86.97 g (0.406 mol) of diphenyl carbonate, and 1.09 mg (12 μmol) of sodium bicarbonate as a catalyst were heated to 180 ° C. under a nitrogen atmosphere and melted. Thereafter, the pressure inside the reactor was set to 20 kPa (150 mmHg) and the temperature was raised to 200 ° C. at a rate of 60 ° C./hr, and the reaction was carried out while maintaining that temperature for 40 minutes. Further, the temperature was raised to 225 ° C. at a rate of 75 ° C./hr, and 40 minutes after the temperature increase was completed, the pressure inside the reactor was reduced to 133 Pa (1 mmHg) or less over 1 hour while maintaining that temperature. The temperature was then raised to 235°C at a rate of 105°C/hr, and the reaction was carried out for a total of 6 hours with stirring. After the reaction was completed, nitrogen was blown into the reactor to return the pressure to normal, and the resulting resin was removed. The copolymerization ratio of the resulting polycarbonate resin derived from BPA and PCPDM was measured by ^1H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated.

<Comparative Example 2>
A polycarbonate resin was produced in the same manner as in Comparative Example 1, except that the charged amounts of BPA and PCPDM were 63.92 g (0.28 mol) and 31.49 g (0.12 mol), respectively. The copolymerization ratio of the resulting polycarbonate resin derived from BPA and PCPDM was measured by ¹ H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated.

<Comparative Example 3>
A polycarbonate resin was produced in the same manner as in Comparative Example 1, except that the amount of BPA charged was 27.40 g (0.12 mol) and the amount of PCPDM charged was 73.47 g (0.28 mol). The copolymerization ratio of the resulting polycarbonate resin derived from BPA and PCPDM was measured by ¹ H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated.

<Comparative Example 4>
103.49 g (0.24 mol) of BPEF, 37.80 g (0.12 mol) of 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro(5.5)undecane (hereinafter referred to as "SPG"), 12.42 g (0.04 mol) of BisTMC, 89.11 g (0.42 mol) of diphenyl carbonate, and 0.033 mL of a 60 mmol/L aqueous sodium bicarbonate solution (sodium bicarbonate 2.0 μmol) as a catalyst were heated to 180 ° C. under a nitrogen atmosphere and melted. Thereafter, the reduced pressure was adjusted to 20 kPa over 10 minutes. The temperature was raised to 250 ° C. at a rate of 60 ° C./hr, and after the phenol outflow rate reached 70%, the pressure inside the reactor was reduced to 133 Pa or less over 1 hour. The reaction was carried out with stirring for a total of 3.5 hours, and after completion of the reaction, the resin was removed from the flask. The copolymerization ratio of the resulting polycarbonate resin derived from BPEF, SPG, and BisTMC was measured by ^1H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated.

Comparative Example 5
A polycarbonate resin was produced in the same manner as in Comparative Example 4, except that the amount of BPEF charged was 96.47 g (0.22 mol), the amount of SPG charged was 38.96 g (0.13 mol), and the amount of BisTMC charged was 16.12 g (0.05 mol). The copolymerization ratio of the resulting polycarbonate resin derived from BPEF, SPG, and BisTMC was measured by ¹ H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated.

<Comparative Example 6>
A polycarbonate resin was produced in the same manner as in Comparative Example 4, except that the amount of BPEF charged was 21.05 g (0.05 mol), the amount of SPG charged was 69.40 g (0.23 mol), and the amount of BisTMC charged was 38.44 g (0.12 mol). The copolymerization ratio of the resulting polycarbonate resin derived from BPEF, SPG, and BisTMC was measured by ¹ H NMR. The weight-average molecular weight Mw, refractive index, Abbe number, θgF, glass transition temperature, thermal decomposition temperature, absolute value of orientation birefringence, and photoelastic coefficient of the polycarbonate resin were evaluated.

Compared to Comparative Examples 1 and 2, which correspond to the examples of Patent Document 1, Examples 1 to 6 of the present invention have superior orientation birefringence, making it less likely that birefringence due to molecular orientation will occur when obtaining optical components by injection molding or the like. Furthermore, because the photoelastic coefficient is small, it is less likely that birefringence due to stress will occur when obtaining optical components by injection molding or the like. Therefore, these are preferable because they reduce the birefringence of the optical components.

Compared to Comparative Example 3, Example 2 of the present invention is preferable because it has a higher glass transition temperature and superior heat resistance.

Compared to Comparative Example 6, which corresponds to the example in Patent Document 4, Examples 1 to 3 and 6 of the present invention have a higher refractive index while maintaining an Abbe number equal to or greater than that of Comparative Example 6, allowing for thinner optical lenses.

Compared to Comparative Example 5, which corresponds to the example in Patent Document 3, Example 4 of the present invention has a higher Abbe number despite having the same refractive index, thereby expanding the scope of optical design.

Compared to Comparative Examples 4 and 5, which correspond to the examples of Patent Document 3, Example 5 of the present invention has a higher Abbe number despite having the same refractive index, thereby expanding the scope of optical design.

As shown in Figure 1, when the refractive index and Abbe number are plotted, the comparative example has an Abbe number of 27.6 at a high refractive index, while the polycarbonate resin of the present invention has an Abbe number of 31.0 at the same refractive index, which is a higher Abbe number relative to the refractive index than the range of conventional technology. Therefore, the chromatic aberration of the optical element can be reduced.

The polycarbonate resin of the present invention is used in optical materials and can be used in optical components such as lenses, prisms, optical disks, transparent conductive substrates, optical cards, sheets, films, optical fibers, optical films, optical filters, and hard coat films, and is particularly useful in imaging lenses.

Claims (11)

A polycarbonate resin comprising a repeating unit represented by formula (1) and/or formula (2), a repeating unit represented by formula (3), and a repeating unit represented by formula (4), wherein the total amount of the repeating units represented by formula (1) and/or formula (2) in all repeating units of the resin is 50 mol % or more, and the polycarbonate resin has a weight average molecular weight Mw of 10,000 or more.
(In the formula, R ¹ to R ⁴ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.)
(In formula (4), n is a number ranging from 0 to 8, and each R represents an alkyl group having 1 to 3 carbon atoms.) The polycarbonate resin according to claim 1, having a weight average molecular weight Mw of 10,000 or more and 60,000 or less. The polycarbonate resin according to claim 1 or 2, wherein the repeating units represented by formula (3) account for more than 0 mol % and not more than 50 mol % of all repeating units of the resin. The polycarbonate resin according to claim 1 or 2, wherein the repeating units of formula (4) account for more than 0 mol % and not more than 40 mol % of all repeating units of the resin. 3. The polycarbonate resin according to claim 1, wherein R ¹ to R ⁴ in the formula (3) are hydrogen atoms. The polycarbonate resin according to claim 1 or 2, wherein the repeating unit of formula (4) is a repeating unit derived from bisphenol TMC. 3. The polycarbonate resin according to claim 1, wherein the absolute value of orientation birefringence is 10.0 × 10 ⁻³ or less. 3. The polycarbonate resin according to claim 1, which has a photoelastic coefficient of less than 25×10 ⁻¹² Pa. The polycarbonate resin according to claim 1 or 2, having an Abbe number of 25.0 or more. An optical component made from the polycarbonate resin described in claim 1 or 2. The optical member according to claim 10 , wherein the optical member is an imaging lens.