Polycarbonate resin and optical member

Abstract

To provide a polycarbonate resin that has a relationship between refractive index and Abbe number comparable to that of bisphenol A-derived polycarbonate resins, and that offer low birefringence and superior thermal resistance, and also to provide an optical member.SOLUTION: A polycarbonate resin comprising a structural unit represented by formula (1) and a structural unit represented by formula (2).SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a polycarbonate resin and an optical member made of the same. [Background technology]

[0002] There is a strong demand for low birefringence and improved aberration correction capabilities in plastic imaging lenses used in devices such as smartphones. Conventionally, such imaging lenses have corrected aberrations by combining multiple lenses with different optical properties (refractive index, Abbe number) and lens shapes.

[0003] Among the transparent optical resins that have been put to practical use in lenses, polycarbonate resin (nd=1.584) made from bisphenol A has been widely used. However, polycarbonate resin made from bisphenol A has a drawback in that it has a large birefringence, making it unsuitable for use in the high-resolution cameras of recent years.

[0004] In recent years, the number of types of optical elements used in imaging modules has increased, and there has been a growing demand for resins for optical lenses with a variety of balances between refractive index and Abbe number. Resins for optical lenses with low refractive index and high Abbe number have been actively developed, and it has been reported that aliphatic diol compounds containing a norbornane skeleton exhibit excellent optical properties in the low refractive index and high Abbe number ranges (Patent Documents 1 and 2). Patent Document 3 also proposes a polycarbonate resin using a novel aliphatic diol compound containing a norbornane skeleton, but the optical properties of the resin are not evaluated. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-302860 [Patent Document 2] International Publication No. 2016 / 052370 [Patent Document 3] Japanese Patent Publication No. 2022-171557 Summary of the Invention [Problem to be solved by the invention]

[0006] Polycarbonate, which uses bisphenol A as a raw material, has excellent optical properties and heat resistance, but has the problem of high birefringence.

[0007] The present invention aims to solve the above problems and to provide a polycarbonate resin that does not use bisphenol A as a raw material, has a relationship between refractive index and Abbe number equivalent to that of polycarbonate resins made from bisphenol A, and has low birefringence and excellent heat resistance, and an optical component containing the polycarbonate resin. [Means for solving the problem]

[0008] As a result of extensive research aimed at achieving this object, the present inventors have discovered that a polycarbonate resin having a specific structure can solve the above-mentioned problems, and have arrived at the present invention.

[0009] (1) A polycarbonate resin containing a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2): [ka] [ka] (In formula (2), R 1 and R 2 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms; L 1 and L 2 each independently represents a divalent linking group, and m and n each independently represent 0 or 1. (2) The polycarbonate resin according to (1) above, wherein the structural units represented by the formula (1) account for 5 mol % to 90 mol % of all structural units constituting the polycarbonate resin. (3) The polycarbonate resin according to the above item (1) or (2), further comprising a structural unit represented by the following formula (3): [ka] (4) The polycarbonate resin according to any one of (1) to (3) above, which has a refractive index of 1.540 to 1.630. (5) The polycarbonate resin according to any one of (1) to (4) above, which has an Abbe number of 20 to 60. (6) The polycarbonate resin according to any one of (1) to (5) above, which has a glass transition temperature of 120°C to 180°C. (7) Orientation birefringence is 5 × 10 -3 The polycarbonate resin according to any one of the above items (1) to (6), which is: (8) The polycarbonate resin according to any one of the above (1) to (7), which has a specific viscosity of 0.12 to 0.50. (9) An optical member obtained by injection molding the polycarbonate resin according to any one of the above items (1) to (8). (10) The optical member according to the above (9), which is an optical lens. [Effects of the Invention]

[0010] The polycarbonate resin of the present invention has a relationship between refractive index and Abbe number equivalent to that of polycarbonate resins made from bisphenol A, and has low birefringence and excellent heat resistance. Therefore, it can be used for optical components such as optical lenses, prisms, optical disks, transparent conductive substrates, optical cards, sheets, films, optical fibers, optical films, optical filters, and hard coat films. It is particularly useful for optical lenses used in mobile phones, smartphones, tablet devices, personal computers, digital cameras, video cameras, in-vehicle cameras, and surveillance cameras, and therefore has exceptional industrial effects. [Brief explanation of the drawings]

[0011] [Figure 1] 1H NMR of the polycarbonate resin obtained in Example 1. [Figure 2] 1H NMR of the polycarbonate resin obtained in Example 2. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will now be described in more detail.

[0013] <Polycarbonate resin> The polycarbonate resin of the present invention is a polycarbonate resin containing a constitutional unit represented by the following formula (1) and a constitutional unit represented by the following formula (2).

[0014] [ka]

[0015] [ka]

[0016] (In formula (2), R 1 and R 2 are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms; L 1 and L 2 each independently represents a divalent linking group, and m and n each independently represent 0 or 1. In the formula (2), R 1 and R 2 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, preferably a hydrogen atom, a methyl group, a phenyl group, or a naphthyl group, more preferably a hydrogen atom, a methyl group, or a phenyl group, and even more preferably a hydrogen atom or a methyl group.

[0017] In the formula (2), L 1 , L 2L each independently represents a divalent linking group, and is preferably an alkylene group having 1 to 12 carbon atoms, more preferably an alkylene group having 1 to 4 carbon atoms, and even more preferably an ethylene group. 1 , L 2 By adjusting the length of the linking group, the glass transition temperature (Tg) of the resin can be adjusted.

[0018] The compounds represented by formula (1) and formula (2) can be obtained from a diol compound and a carbonate precursor such as a carbonate ester.

[0019] In the polycarbonate resin of the present invention containing the structural units represented by the formula (1) and the formula (2), it is preferred that the structural units represented by the formula (1) and the formula (2) account for 50 mol% or more, 55 mol% or more, 60 mol% or more, 65 mol% or more, or 70 mol% or more of the total structural units constituting the polycarbonate resin.

[0020] In the polycarbonate resin of the present invention, of all the structural units constituting the polycarbonate resin, the structural unit represented by formula (1) may be contained in an amount of 5 mol% or more, 10 mol% or more, 15 mol% or more, 20 mol% or more, 25 mol% or more, or 30 mol% or more, or 90 mol% or less, 80 mol% or less, 70 mol% or less, 60 mol% or less, 50 mol% or less, 45 mol% or less, 40 mol% or less, or 35 mol% or less.

[0021] In the polycarbonate resin of the present invention, the structural unit represented by formula (1) can be contained in an amount of preferably 5 mol% to 90 mol%, more preferably 10 mol% to 80 mol%, even more preferably 15 mol% to 70 mol%, particularly preferably 20 mol% to 60 mol%, and most preferably 20 mol% to 50 mol% of all structural units constituting the polycarbonate resin. When the proportion of the structural unit represented by formula (1) is within the above range, the polycarbonate resin has an appropriate refractive index and Abbe number, and is excellent in heat resistance and heat stability, which is preferable.

[0022] Furthermore, in the polycarbonate resin of the present invention, of all the structural units constituting the polycarbonate resin, the structural unit represented by formula (2) may be contained in an amount of 10 mol% or more, 20 mol% or more, 30 mol% or more, 35 mol% or more, or 40 mol% or more, or 95 mol% or less, 90 mol% or less, 85 mol% or less, 80 mol% or less, 75 mol% or less, 70 mol% or less, 65 mol% or less, or 60 mol% or less.

[0023] In the polycarbonate resin of the present invention, the structural unit represented by formula (2) can be contained in an amount of preferably 10 mol% to 95 mol%, more preferably 20 mol% to 90 mol%, even more preferably 30 mol% to 85 mol%, particularly preferably 35 mol% to 80 mol%, and most preferably 40 mol% to 75 mol% of all structural units constituting the polycarbonate resin. When the proportion of the structural unit represented by formula (2) is within the above range, the polycarbonate resin has an appropriate refractive index and Abbe number, and is excellent in heat resistance and heat stability, which is preferable.

[0024] The polycarbonate resin of the present invention may further contain a structural unit represented by the following formula (3).

[0025] [ka]

[0026] When the polycarbonate resin contains the structural units represented by the formula (1), the formula (2), and the formula (3), it is preferable that the structural units represented by the formula (1), the formula (2), and the formula (3) account for 70 mol% or more, 75 mol% or more, 80 mol% or more, 85 mol% or more, or 90 mol% or more of the total structural units constituting the polycarbonate resin.

[0027] When a structural unit represented by formula (3) is used in the polycarbonate resin of the present invention, the structural unit represented by formula (3) may be contained in an amount of 5 mol% or more, 10 mol% or more, 15 mol% or more, 20 mol% or more, 25 mol% or more, or 30 mol% or more of all structural units constituting the polycarbonate resin, or 60 mol% or less, 55 mol% or less, 50 mol% or less, 45 mol% or less, 40 mol% or less, 35 mol% or less, or 30 mol% or less.

[0028] When the polycarbonate resin of the present invention uses the structural unit represented by formula (3), the structural unit represented by formula (3) can be contained in an amount of preferably 5 mol% to 60 mol%, more preferably 10 mol% to 55 mol%, even more preferably 15 mol% to 50 mol%, particularly preferably 15 mol% to 45 mol%, and most preferably 15 mol% to 40 mol% of all structural units constituting the polycarbonate resin. When the proportion of the structural unit represented by formula (3) is within the above range, the polycarbonate resin has an appropriate refractive index and Abbe number, and is excellent in heat resistance and heat stability, which is preferable.

[0029] <Physical properties of polycarbonate resin> The refractive index of the polycarbonate resin of the present invention, when measured at a temperature of 20°C and a wavelength of 587.56 nm, may be 1.540 or more, 1.550 or more, 1.560 or more, 1.570 or more, or 1.580 or more, or may be 1.630 or less, 1.620 or less, 1.610 or less, 1.600 or less, or 1.590 or less.

[0030] The refractive index of the polycarbonate resin of the present invention is preferably 1.540 to 1.630, more preferably 1.550 to 1.620, even more preferably 1.560 to 1.610, particularly preferably 1.570 to 1.600, and most preferably 1.580 to 1.590.

[0031] The Abbe number (νd) of the polycarbonate resin of the present invention may be 20 or more, 21 or more, 22 or more, 23 or more, 24 or more, 25 or more, 26 or more, or 27 or more, or may be 60 or less, 55 or less, 50 or less, 45 or less, 40 or less, or 35 or less. The Abbe number is preferably 20 to 60, more preferably 25 to 50, and even more preferably 27 to 35.

[0032] Here, the Abbe number is calculated using the following formula from the refractive indexes 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: Refractive index at a wavelength of 656.27 nm.

[0033] The refractive index and Abbe number of the polycarbonate resin of the present invention preferably satisfy the following formula (A). nd≧-0.0093×νd+1.8557 (A)

[0034] The refractive index and Abbe number of the polycarbonate resin of the present invention may satisfy the following mathematical formula (B). nd≦-0.0093×νd+1.8737 (B)

[0035] When the refractive index and Abbe number are within the above ranges, the relationship of the Abbe number to the refractive index is close to that of bisphenol A, and the resin has excellent optical properties, which is preferable.

[0036] The polycarbonate resin of the present invention may have a glass transition temperature (Tg) of 120°C or higher, 125°C or higher, 130°C or higher, or 135°C or higher, or 180°C or lower, 175°C or lower, 170°C or lower, 165°C or lower, or 160°C or lower. The Tg is preferably from 120°C to 180°C, more preferably from 125°C to 170°C, even more preferably from 130°C to 160°C, and particularly preferably from 135°C to 160°C. A glass transition temperature within the above range is preferred because it provides an excellent balance between heat resistance and moldability.

[0037] The absolute value of the orientation birefringence (Δn) of the polycarbonate resin of the present invention is 5.0×10 -3 Below, 4.0 x 10 -3 Below, 3.0 x 10 -3 Preferably, the orientation birefringence (Δn) is measured at a wavelength of 589 nm after a cast film having a thickness of 100 μm obtained from the polycarbonate resin is stretched to 2 times its original length at Tg+10°C.

[0038] The specific viscosity of the polycarbonate resin of the present invention is preferably 0.12 to 0.50, more preferably 0.14 to 0.48, and even more preferably 0.16 to 0.46. A specific viscosity within the above range is preferred because it provides an excellent balance between moldability and mechanical strength.

[0039] The specific viscosity was measured by measuring the specific viscosity (η) of a solution of 0.7 g of polycarbonate resin dissolved in 100 ml of methylene chloride at 20°C. SP ) is measured using an Ostwald viscometer and calculated using the following formula: Specific viscosity (η SP )=(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.)

[0040] <Raw material for polycarbonate resin> (Diol component of formula (1)) The diol component that is the raw material of formula (1) is a diol component represented by the following formula (a).

[0041] [ka]

[0042] The diol compound represented by compound (a) exists as a cis isomer represented by formula (a-1) or a trans isomer represented by formula (a-2) depending on the position of addition of methanol, and may be either a single positional isomer or a mixture of these positional isomers. In the case of a mixture, the mixture is an isomer mixture in which the mixing ratio of the cis isomer of compound (a-1) to the trans isomer of compound (a-2) is 0.001:100 to 100:0.001.

[0043] [ka]

[0044] [ka]

[0045] (Diol component of formula (2)) The diol compounds that serve as raw materials for the formula (2) are shown below. These may be used alone or in combination of two or more.

[0046] The diol compound component used as the raw material of the formula (2) of the present invention is 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-methylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-cyclohexylphenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, 9,9-bis(4-hydroxyphenyl)fluorene, 9,9- Examples include bis(4-hydroxy-3-methylphenyl)fluorene, 9,9-bis(4-hydroxy-3-cyclohexylphenyl)fluorene, and 9,9-bis(4-hydroxy-3-phenylphenyl)fluorene, and 9,9-bis(4-(2-hydroxyethoxy)phenyl)fluorene, 9,9-bis(4-(2-hydroxyethoxy)-3-phenylphenyl)fluorene, and 9,9-bis(4-hydroxy-3-methylphenyl)fluorene are particularly preferred. These may be used alone or in combination of two or more.

[0047] (Diol component of formula (3)) The polycarbonate resin of the present invention may further have a structural unit of the formula (3), and the diol compound component that is the raw material for the formula (3) is a diol compound represented by the following formula (c).

[0048] [ka]

[0049] (Copolymerization components other than those of the formulas (1) to (3)) The polycarbonate resin of the present invention may be copolymerized with other diol compound components to the extent that the properties of the present invention are not impaired. The amount of the other diol compound components is preferably 30 mol % or less, 25 mol % or less, 20 mol % or less, 15 mol % or less, or 10 mol % or less of all repeating units.

[0050] Other diol compound components that can be used in the polycarbonate resin of the present invention include ethylene glycol, propanediol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, tricyclo[5.2.1.0]diol, and the like. 2,6 ]Decanedimethanol, cyclohexane-1,4-dimethanol, decalin-2,6-dimethanol, norbornane dimethanol, pentacyclopentadecanedimethanol, cyclopentane-1,3-dimethanol, isosorbide, isomannide, isoidide, hydroquinone, resorcinol, bis(4-(2-hydroxyethoxy)phenyl)sulfone, 1,1'-bi-2-naphthol, diolnaphthalene, bis(2-hydroxyethoxy)naphthalene, and the like are exemplified, and these may be used alone or in combination of two or more.

[0051] <Manufacturing method> The polycarbonate resin of the present invention can be obtained by a known reaction method, for example, by reacting a diol compound component with a carbonate precursor by melt polymerization. In producing the polycarbonate resin, a catalyst, a terminal terminator, an antioxidant, etc. may be used as necessary.

[0052] <Optical components> The optical member of the present invention is formed from the polycarbonate resin. Such an optical member is not particularly limited as long as it is for an optical application in which the polycarbonate resin is useful, and examples of such an optical member include an optical disk, a transparent conductive substrate, an optical card, a sheet, a film, an optical fiber, a lens, a prism, an optical film, a substrate, an optical filter, and a hard coat film.

[0053] The optical member of the present invention is composed of a resin composition containing the above-mentioned polycarbonate resin, and the resin composition may contain additives such as a heat stabilizer, a release agent, a plasticizer, a light stabilizer, a polymerized metal deactivator, a flame retardant, a lubricant, an antistatic agent, a surfactant, an antibacterial agent, an antioxidant, and an ultraviolet absorber, as needed.

[0054] Examples of heat stabilizers include phosphorus-based heat stabilizers, sulfur-based heat stabilizers, and hindered phenol-based heat stabilizers. Phosphorus-based heat stabilizers include phosphorous acid, phosphoric acid, phosphonous acid, phosphonic acid, and their esters. Specific examples include bis(2,4-dicumylphenyl)pentaerythritol diphosphite, tris(2,4-di-tert-butylphenyl)phosphite, tris(2,6-di-tert-butylphenyl)phosphite, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)stearyl propionate, [1,1-biphenyl]-4,4-diylbis[bis(2,4-di-tert-butylphenoxy)phosphine], 3,9-bis(2,6-di-tert-butylphenyl)propionate ... butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane is preferred, and tris(2,4-di-tert-butylphenyl)phosphite, 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate stearyl, and 3,9-bis(2,6-di-tert-butyl-4-methylphenoxy)-2,4,8,10-tetraoxa-3,9-diphosphaspiro[5.5]undecane are more preferred.

[0055] The amount of the heat stabilizer to be added is preferably in the range of 0.001 to 0.5 parts by weight, more preferably 0.005 to 0.4 parts by weight, and even more preferably 0.01 to 0.3 parts by weight, relative to 100 parts by weight of the polycarbonate resin.

[0056] Preferably, the release agent is one that is composed of 90% by weight or more of an ester of alcohol and fatty acid. Specific examples of the ester of alcohol and fatty acid include ester of monohydric alcohol and fatty acid, and partial or complete ester of polyhydric alcohol and fatty acid. Specific examples of the ester of monohydric alcohol and saturated fatty acid include stearyl stearate, palmityl palmitate, butyl stearate, methyl laurate, and isopropyl palmitate. Stearyl stearate is preferred. Examples of partial or full esters of polyhydric alcohols and saturated fatty acids include stearic acid monoglyceride, stearic acid diglyceride, stearic acid triglyceride, stearic acid monosorbitate, behenic acid monoglyceride, pentaerythritol monostearate, pentaerythritol tetrastearate, pentaerythritol tetrapelargonate, propylene glycol monostearate, biphenyl biphenate, sorbitan monostearate, 2-ethylhexyl stearate, and full or partial esters of dipentaerythritol such as dipentaerythritol hexastearate. Among these esters, stearic acid monoglyceride, stearic acid triglyceride, pentaerythritol tetrastearate, and mixtures of stearic acid triglyceride and stearyl stearate are preferred, with stearic acid monoglyceride and pentaerythritol tetrastearate being more preferred.

[0057] The amount of the release agent to be added is preferably in the range of 0.05 to 0.5 parts by weight, more preferably 0.1 to 0.4 parts by weight, and even more preferably 0.12 to 0.3 parts by weight, relative to 100 parts by weight of the polycarbonate resin.

[0058] <Optical lenses> The optical member of the present invention can particularly include an optical lens, such as an optical lens for a mobile phone, a smartphone, a tablet terminal, a personal computer, a digital camera, a video camera, an in-vehicle camera, or a surveillance camera.

[0059] The optical lens of the present invention can be molded and processed by any method such as injection molding, compression molding, injection compression molding, melt extrusion molding, casting, etc., with injection molding being particularly suitable.

[0060] The molding conditions for injection molding are not particularly limited, but the cylinder temperature of the molding machine is preferably 180 to 320° C., more preferably 220 to 300° C., and particularly preferably 240 to 280° C. The mold temperature is preferably 70 to 130° C., more preferably 80 to 125° C., and particularly preferably 90 to 120° C. The injection pressure is preferably 5 to 170 MPa, more preferably 50 to 160 MPa, and particularly preferably 100 to 150 MPa. [Example]

[0061] The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. The evaluation was carried out according to the following methods.

[0062] <Specific viscosity measurement> The viscosity was measured using an Ostwald viscometer from a solution prepared by dissolving 0.7 g of the obtained resin in 100 ml of methylene chloride at 20°C. Specific viscosity (η SP )=(t-t0) / t0 (t0 is the number of seconds that methylene chloride falls, and t is the number of seconds that the sample solution falls)

[0063] <Copolymerization ratio> The obtained resin was subjected to a filtration process using JNM-ECZ400S manufactured by JEOL Ltd. 1 The composition ratio of each polycarbonate resin was calculated by H NMR measurement. DMSO-d6 was used as the solvent.

[0064] <Heat resistance> (glass transition temperature (Tg)) The obtained resin was measured at a heating rate of 20°C / min using a TA Instruments Discovery SDT650 differential thermal and thermogravimetric simultaneous analyzer. The sample was approximately 5 mg.

[0065] <Optical properties> (refractive index) A 3 mm thick test piece of each resin was prepared and polished, and then the refractive index nd (587.56 nm) at 20° C. was measured using a Kalnew precision refractometer KPR-2000 manufactured by Shimadzu Corporation.

[0066] (Abbe number) The Abbe number was calculated from the refractive indexes at 486.13 nm, 587.56 nm, and 656.27 nm using the following formula: 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: Refractive index at a wavelength of 656.27 nm.

[0067] (Absolute value of orientation birefringence) Polycarbonate resin was dissolved in methylene chloride, cast onto a glass dish, and thoroughly dried to prepare a 100 μm thick cast film. The film was stretched twice at Tg+10°C, and the retardation (Re) at 589 nm was measured using an Ellipsometer M-220 manufactured by JASCO Corporation. 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)

[0068] (Evaluation of lens optical distortion) An aspherical lens with a thickness of 0.2 mm, a convex curvature radius of 5 mm, a concave curvature radius of 4 mm, and a diameter of 5 mm was injection molded using an SE30DU injection molding machine manufactured by Sumitomo Heavy Industries, Ltd., with a cylinder temperature of 280°C and a mold temperature of 120°C. The aspherical lens was sandwiched between two polarizing plates and optical distortion was evaluated by visually checking for light leakage using the crossed Nicols method. Evaluation was based on the following criteria. ◎: Almost no light leakage. ◯: Slight light leakage is observed. △: There is light leakage. ×: Light leakage is significant.

[0069] [Example 1] A mixture of 4.6 parts by mass (15 mol%) of diol compound (a) (hereinafter sometimes abbreviated as DOAM), 19.73 parts by mass (45 mol%) of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (hereinafter sometimes abbreviated as BPEF), 12.18 parts by mass (40 mol%) of 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (hereinafter sometimes abbreviated as SPG), 21.64 parts by mass (101 mol%) of diphenyl carbonate (hereinafter sometimes abbreviated as DPC), and 8.4 × 10 sodium bicarbonate at a concentration of 60 mmol / L as a catalyst was used. ―4 Part of mass (1.0×10 -2 mol%), tetramethylammonium hydroxide 2.7 × 10 at a concentration of 274 mmol / L -3 Part of mass (3.0×10 -2 % (mol) was added and heated to 200°C under a nitrogen atmosphere to melt. The vacuum was then adjusted to 20 kPa over 5 minutes. The temperature was then raised to 240°C at a rate of 40°C / hr. After the amount of phenol flowing out reached 70%, the temperature was raised to 250°C at a rate of 60°C / hr and the vacuum was reduced to 1 kPa. The polymerization reaction was carried out until the specified power was reached, and after the reaction was completed, the resin was removed from the flask. The obtained polycarbonate resin was 1 Analysis by H NMR confirmed that the DOAM component was 15 mol% of the total monomers, the BPEF component was 45 mol% of the total monomers, and the SPG component was 40 mol%. Using this polycarbonate resin, the copolymerization ratio, Tg, specific viscosity, refractive index, Abbe number, absolute value of orientation birefringence, and optical distortion of the lens were evaluated, and the results are shown in Table 1.

[0070] [ka]

[0071] [Example 2] Polycarbonate resins were produced in the same manner as in Example 1, except that the amounts of each monomer were changed to those shown in Table 1. Using the polycarbonate resins, the copolymerization ratio, Tg, specific viscosity, refractive index, Abbe number, absolute value of orientation birefringence, and lens optical distortion were evaluated, and the results are shown in Table 1.

[0072] [Example 3] Polycarbonate resins were produced in the same manner as in Example 1, except that the amounts of each monomer were changed to those shown in Table 1. Using the polycarbonate resins, the copolymerization ratio, Tg, specific viscosity, refractive index, Abbe number, absolute value of orientation birefringence, and lens optical distortion were evaluated, and the results are shown in Table 1.

[0073] [Example 4] Polycarbonate resins were produced in the same manner as in Example 1, except that the amounts of each monomer were changed to those shown in Table 1. Using the polycarbonate resins, the copolymerization ratio, Tg, specific viscosity, refractive index, Abbe number, absolute value of orientation birefringence, and lens optical distortion were evaluated, and the results are shown in Table 1.

[0074] [ka]

[0075] [Comparative Example 1] A polycarbonate resin was produced in the same manner as in Example 1, except that bisphenol A was used instead of DOAM and only sodium bicarbonate was used as the catalyst. Using this polycarbonate resin, the copolymerization ratio, Tg, specific viscosity, refractive index, Abbe number, and lens optical distortion were evaluated, and the results are shown in Table 1. The cast film became cloudy, so the absolute value of orientation birefringence could not be measured.

[0076] [Table 1]

[0077] The polycarbonate resins obtained in Examples 1 to 4 have a relationship between refractive index and Abbe number equivalent to that of polycarbonate resins made from bisphenol A, and have a Tg between 130 and 160°C, providing an excellent balance between moldability and heat resistance. In addition, they have small birefringence, making them excellent for use as optical lenses. [Industrial Applicability]

[0078] The polycarbonate resin of the present invention has a relationship between refractive index and Abbe number equivalent to that of polycarbonate resins made from bisphenol A, and has low birefringence and excellent heat resistance, and is therefore suitable for use as an optical material. Specifically, it can be used as optical components such as optical 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 as an optical lens material.

Claims

1. A polycarbonate resin comprising a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2): 【Chemical 1】 【Chemistry 2】 (In formula (2), R １ and R ２ are the same or different and represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms; L １ and L ２ each independently represents a divalent linking group, and m and n each independently represent 0 or 1.

2. 2. The polycarbonate resin according to claim 1, wherein the structural unit represented by formula (1) accounts for 5 mol % to 90 mol % of all structural units constituting the polycarbonate resin.

3. The polycarbonate resin according to claim 1, further comprising a structural unit represented by the following formula (3): 【Chemistry 3】

4. 2. The polycarbonate resin according to claim 1, which has a refractive index of 1.540 to 1.

630.

5. 2. The polycarbonate resin according to claim 1, which has an Abbe number of 20 to 60.

6. 2. The polycarbonate resin according to claim 1, which has a glass transition temperature of 120°C to 180°C.

7. Orientation birefringence is 5 × 10 －３ 2. The polycarbonate resin according to claim 1, wherein:

8. 2. The polycarbonate resin according to claim 1, which has a specific viscosity of 0.12 to 0.

50.

9. An optical member obtained by injection molding the polycarbonate resin according to any one of claims 1 to 8.

10. The optical member according to claim 9, which is an optical lens.

Images