Thermoplastic resin and optical member containing the same

Abstract

To provide a polycarbonate resin that exhibits a high Abbe number along with superior birefringence and θgF characteristics.SOLUTION: The present invention provides: a thermoplastic resin including a repeating unit represented by formula (1), a repeating unit derived from 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane, and a repeating unit represented by formula (3), wherein the content of formula (1) is more than 30 mol% and less than 50 mol%, and the content of formula (3) is 30 mol% or less; and an optical member.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermoplastic resin and an optical member containing 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] In recent years, it has become common to create lens units by combining high refractive index, low Abbe number resins (Abbe number of approximately 20) with cycloolefin-based low refractive index, high Abbe number resins (Abbe number of approximately 55). Furthermore, by using medium refractive index, medium Abbe number resins to create high-performance lens units, the scope of lens design has expanded, enabling fine adjustments to achieve advanced performance. This has led to an increase in demand for medium refractive index, medium Abbe number resins.

[0004] However, when optical transparent resins are used as optical lenses, in addition to refractive index and Abbe number, transparency, heat resistance, and low birefringence are required, so the areas where they can be used are limited by the balance of the resin's properties. For example, polystyrene has low heat resistance and high birefringence, poly-4-methylpentene has low heat resistance, polymethyl methacrylate has a low glass transition temperature and low heat resistance, and polycarbonate made from bisphenol A has high birefringence, so their areas of use are limited.

[0005] Furthermore, Patent Documents 1 to 3 describe polycarbonate resins comprising units having a fluorene skeleton, units having a spiroundecane skeleton, and units having a bisphenol skeleton. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2019 / 188702 [Patent Document 2] International Publication No. 2020 / 162533 [Patent Document 3] International Publication No. 2022 / 004239 Summary of the Invention [Problem to be solved by the invention]

[0007] The polycarbonate resin described in Patent Document 1 has a low Abbe number, while the polycarbonate resins described in Patent Documents 2 and 3 have a large birefringence (Δn) and a small partial dispersion ratio (θgF). Therefore, an object of the present invention is to provide a polycarbonate resin having a high Abbe number, excellent birefringence and θgF, and an excellent balance between the Abbe number, birefringence, and θgF, and an optical member containing the same. [Means for solving the problem]

[0008] The present inventors have found that the above problems can be solved by the present invention having the following aspects.

[0009] <<Aspect 1>> A thermoplastic resin containing repeating units represented by formula (1), formula (2), and formula (3), in which the repeating units represented by formula (1) account for more than 30 mol% but less than 50 mol%, and the repeating units represented by formula (3) account for 30 mol% or less.

[0010] [ka] (In formula (1), R 1 ~R 4 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. [ka] [ka] (In formula (3), n is in the range of 1 to 8, and R 5 and R 6 each independently represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms; R 7 represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms)

[0011] <<Aspect 2>> Aspect 2. The thermoplastic resin according to aspect 1, wherein the repeating unit of formula (2) is 30 mol % or more and 60 mol % or less. <Aspect 3> R in the formula (1) 1 ~R 4 is a hydrogen atom. <<Aspect 4>> 4. The thermoplastic resin according to any one of aspects 1 to 3, wherein the repeating unit of formula (3) is a repeating unit derived from 4,4'-(3,3,5-trimethylcyclohexylidene)bisphenol. <Aspect 5> Aspect 5. The thermoplastic resin according to any one of aspects 1 to 4, having an Abbe number of 29 to 35. Aspect 6 The absolute value of orientation birefringence is 3.7 × 10 -3 A thermoplastic resin according to any one of aspects 1 to 5, wherein: Aspect 7 A thermoplastic resin according to any one of aspects 1 to 6, having a partial dispersion ratio (θgF) of 0.615 or more. <Aspect 8> An optical member comprising the thermoplastic resin according to any one of embodiments 1 to 7. <Aspect 9> 9. The optical member according to embodiment 8, which is an optical lens. [Effects of the Invention]

[0012] The polycarbonate resin of the present invention has a high Abbe number, excellent birefringence and θgF, and an excellent balance between the Abbe number, birefringence, and θgF, and therefore has exceptional industrial effects. DETAILED DESCRIPTION OF THE INVENTION

[0013] <Thermoplastic resin> The thermoplastic resin of the present invention contains repeating units represented by the above formula (1), formula (2), and formula (3), and the repeating units represented by formula (1) account for more than 30 mol % but less than 50 mol %, and the repeating units represented by formula (3) account for 30 mol % or less.

[0014] The present inventors have found that the above thermoplastic resin exhibits an Abbe number useful for producing optical lens units. Furthermore, they have also found that it has excellent birefringence and θgF, as well as an excellent balance of the Abbe number, birefringence, and θgF, which led to the present application.

[0015] <Thermoplastic resin structure> R in the above formula (1) 1 ~R 4 each independently represents 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.

[0016] Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and a t-butyl group, with a methyl group and an ethyl group being preferred.

[0017] Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a bicyclo[1.1.1]pentanyl group.

[0018] Examples of the aryl group include a phenyl group, a tolyl group, a naphthyl group, and a xylyl group, with a phenyl group being preferred.

[0019] R 1 ~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 R 1 and R 2are each independently a hydrogen atom or a phenyl group, and R 3 and R 4 is more preferably a hydrogen atom.

[0020] The repeating unit represented by the above formula (1) is preferably a repeating unit derived from 9,9-bis(4-(hydroxyethoxy)phenyl)fluorene or 9,9-bis(4-(hydroxyethoxy)-3-phenylphenyl)fluorene, and more preferably a repeating unit derived from 9,9-bis(4-(hydroxyethoxy)phenyl)fluorene.

[0021] The thermoplastic resin of the present invention contains the repeating unit of the above formula (1) in an amount of more than 30 mol % but less than 50 mol %, preferably 33 mol % or more, more preferably 36 mol % or more, and even more preferably 39 mol % or more, and preferably 47 mol % or less, more preferably 44 mol % or less, and even more preferably 41 mol % or less.

[0022] When the repeating unit represented by the above formula (1) is within the above range, it is possible to obtain a thermoplastic resin that has a high Abbe number, excellent birefringence and θgF, and an excellent balance of Abbe number, birefringence and θgF.

[0023] The repeating unit represented by the above formula (2) is a repeating unit derived from 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane.

[0024] The thermoplastic resin of the present invention preferably contains 30 mol% or more, more preferably 35 mol% or more, and even more preferably 40 mol% or more of the repeating unit of formula (2). The thermoplastic resin of the present invention preferably contains 60 mol% or less, more preferably 55 mol% or less, and even more preferably 50 mol% or less of the repeating unit of formula (2). When the repeating unit represented by formula (2) is within the above range, a thermoplastic resin having a high Abbe number, excellent birefringence and θgF, and an excellent balance of Abbe number, birefringence, and θgF can be obtained.

[0025] The thermoplastic resin of the present invention contains 30 mol % or less, preferably 25 mol % or less, more preferably 20 mol % or less, and even more preferably 15 mol % or less of the repeating unit of the above formula (3). When the repeating unit represented by the above formula (3) is in the above range, a thermoplastic resin having a high Abbe number, excellent birefringence and θgF, and an excellent balance of the Abbe number, birefringence, and θgF can be obtained.

[0026] In the above formula (3), n represents a value ranging from 1 to 8, preferably 1 to 5, more preferably 1 to 3, and even more preferably 3. When n is within the above range, the heat resistance of the resulting resin is improved, which is preferable.

[0027] Also, R 5 , R 6 each independently represents 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.

[0028] Examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, and a t-butyl group, with a methyl group and an ethyl group being preferred.

[0029] Examples of the cycloalkyl group include a cyclopropyl group, a cyclobutyl group, a cyclopentyl group, a cyclohexyl group, and a bicyclo[1.1.1]pentanyl group.

[0030] Examples of the aryl group include a phenyl group, a tolyl group, a naphthyl group, and a xylyl group, with a phenyl group being preferred.

[0031] R 5 , R 6 are each independently preferably a hydrogen atom, a methyl group, or a phenyl group, more preferably a hydrogen atom or a phenyl group, and even more preferably a hydrogen atom.

[0032] R 7represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, preferably a methyl group or an ethyl group, more preferably a methyl group.

[0033] R 5 , R 6 When the substituent of R is as described above, the amount of the above formula (3) introduced can be increased without significantly increasing the refractive index, and therefore high heat resistance is possible. 7 When the substituent is as described above, it becomes possible to further improve the heat resistance.

[0034] The repeating unit represented by the above formula (3) is preferably a repeating unit derived from 4,4'-(3,3,5-trimethylcyclohexylidene)bisphenol, 4,4'-cyclohexylidenebisphenol, or 4,4'-(3-methylcyclohexylidene)bisphenol, and more preferably a repeating unit derived from 4,4'-(3,3,5-trimethylcyclohexylidene)bisphenol or 4,4'-cyclohexylidenebisphenol.

[0035] The thermoplastic resin of the present invention may contain repeating units other than those represented by the above formulas (1), (2) and (3) 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]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, 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)-2-propyl)benzene, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfide, biphenol, bisphenolfluorene, biscresolfluorene, etc. Such repeating units may account for 10 mol% or less of all repeating units.

[0036] The thermoplastic resin of the present invention preferably does not have a phenolic hydroxyl group at the terminal. That is, when a monomer that produces a repeating unit represented by the above formula (3) is polymerized and bonded to the terminal, the terminal group becomes a phenolic hydroxyl group. Therefore, it is preferable to use a carbonic acid diester in excess of the dihydroxy compound used as the raw material during polymerization, for example, to convert the terminal into a phenyl group, thereby reducing the amount of terminal phenolic hydroxyl groups in the thermoplastic resin. The ratio of terminal phenolic hydroxyl groups is Terminal phenolic hydroxyl group ratio = (amount of terminal phenolic hydroxyl groups / total amount of terminals) x 100 The total terminals consist of a terminal phenolic hydroxyl group, a terminal alcoholic hydroxyl group, and a terminal phenyl group.

[0037] Although not limited to this example, specifically, the terminal phenolic hydroxyl group ratio can be determined by the following method.

[0038] (1) The terminal phenolic hydroxyl group of the thermoplastic resin 1Observe by H NMR measurement, take the integral of the relevant peak and set this as 1. At the same time, calculate the integral intensity (A) of one proton of the fluorene structure from the integrated intensity of the peaks at positions 4 and 5 of the fluorene structure derived from the above formula (1). Naturally, when no peak of the terminal phenolic hydroxyl group is observed, the ratio of the terminal phenolic hydroxyl group is 0.

[0039] (2) The average degree of polymerization of the thermoplastic resin is calculated from the number average molecular weight obtained by GPC measurement of the thermoplastic resin and the molecular weight and molar ratio of each repeating unit, and the terminal 1 The integrated intensity (B) in the H NMR spectrum is calculated using the following formula: (B) = (A) × 100 × 2 / ([mol% of the above formula (1)] × average degree of polymerization)

[0040] (3) The terminal phenolic hydroxyl group ratio is calculated as 1 / (B) × 100.

[0041] The ratio of terminal phenolic hydroxyl groups to all terminals of the thermoplastic 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.

[0042] <Thermoplastic resin physical properties> The refractive index of the thermoplastic resin of the present invention, when measured at a temperature of 20°C and a wavelength of 587.56 nm, is preferably 1.530 or more, more preferably 1.540 or more, even more preferably 1.550 or more, and particularly preferably 1.560 or more. It is also preferably 1.600 or less, more preferably 1.590 or less, even more preferably 1.580 or less, and particularly preferably 1.570 or less. A refractive index within the above range is preferred because it broadens the scope of lens design and enables the creation of high-performance lens units.

[0043] The Abbe number of the thermoplastic resin of the present invention is preferably 29.0 to 35.0, preferably 29.5 or more, more preferably 30.0 or more, and even more preferably 30.5 or more. It is also preferably 34.5 or less, more preferably 33.0 or less, and even more preferably 32.0 or less. An Abbe number within the above range is preferred because it broadens the scope of lens design and allows for the creation of high-performance lens units.

[0044] 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: Refractive index at a wavelength of 656.27 nm.

[0045] The partial dispersion ratio (θgF) of the thermoplastic resin of the present invention is preferably 0.615 or more, more preferably 0.618 or more, and even more preferably 0.620 or more. Materials with a high θgF (exhibiting large anomalous dispersion characteristics) are preferred because they can effectively correct or reduce chromatic aberration (shift in imaging position due to wavelength).

[0046] Here, the partial dispersion ratio (θgF) is calculated using the following formula from the refractive indexes at a temperature of 20° C. and wavelengths of 435.83 nm, 486.13 nm, and 656.27 nm. θgF=(ng-nF) / (nF-nC) ng: refractive index at wavelength 435.83 nm, nF: refractive index at a wavelength of 486.13 nm, nC: Refractive index at a wavelength of 656.27 nm.

[0047] The specific viscosity of the thermoplastic resin of the present invention is preferably 0.12 to 0.32, and more preferably 0.18 to 0.30. When the specific viscosity is 0.12 to 0.32, an excellent balance between moldability and strength is achieved.

[0048] The specific viscosity is measured by dissolving 0.7 g of the thermoplastic resin in 100 ml of methylene chloride, measuring the specific viscosity (ηSP) at 20° C. with an Ostwald viscometer, and calculating 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]

[0049] The absolute value of the orientation birefringence (Δn) of the thermoplastic resin of the present invention is 3.7×10 -3 Preferably, it is 3.5 x 10 or less. -3 More preferably, it is 3.0×10 or less. -3 More preferably, it is 2.5×10 or less. -3 It is particularly preferred that:

[0050] If the absolute value of orientation birefringence is below the above range, it will not have a significant effect on chromatic aberration, and performance can be maintained as per the optical design. Orientation birefringence is measured at a wavelength of 589 nm after a 100 μm thick cast film obtained from the thermoplastic resin is stretched twice at Tg+10°C.

[0051] The thermoplastic resin of the present invention preferably has a total light transmittance at a thickness of 1 mm of 80% or more, more preferably 85% or more, and particularly preferably 88% or more.

[0052] The saturated water absorption of the thermoplastic resin of the present invention may be 0.10% to 0.70%, 0.20% to 0.70%, or 0.30% to 0.65%.

[0053] The glass transition temperature of the thermoplastic resin of the present invention is preferably 120° C. to 160° C., more preferably 125° C. to 155° C., and particularly preferably 130° C. to 150° C. A glass transition temperature within the above range is preferred because it provides an excellent balance between the moldability during lens molding and the heat resistance of the lens after lens molding.

[0054] Examples of the thermoplastic resin of the present invention include polycarbonates containing carbonate structures represented by formula (1), formula (2), and formula (3) in their repeating units, and polyester carbonates containing repeating units represented by formula (1), formula (2), and formula (3) and ester structures other than these in their repeating units. Among these, polycarbonates are preferred in terms of heat resistance and moist heat resistance.

[0055] <Manufacturing method of polycarbonate resin> The polycarbonate resin of the present invention can be produced by the methods described in Patent Documents 1-3.

[0056] <Thermoplastic resin composition> If necessary, additives such as a mold release agent, a heat stabilizer, 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, and an antibacterial agent can be appropriately added to the thermoplastic resin of the present invention and used as a resin composition, and examples of such additives include those described in Patent Documents 1 to 3.

[0057] <Optical components> The optical member of the present invention contains the above-mentioned thermoplastic resin. Such an optical member is not particularly limited as long as it is used for optical applications in which the above-mentioned thermoplastic resin is useful, and examples thereof include optical disks, transparent conductive substrates, optical cards, sheets, films, optical fibers, lenses, prisms, optical films, substrates, optical filters, and hard coat films.

[0058] The optical member of the present invention may be composed of a resin composition containing the above-mentioned thermoplastic resin, and the resin composition may contain additives such as a heat stabilizer, a plasticizer, a light stabilizer, a polymerized metal deactivator, a flame retardant, a lubricant, an antistatic agent, a surfactant, an antibacterial agent, an ultraviolet absorber, a release agent, a bluing agent, a filler, and an antioxidant, as needed.

[0059] <Optical lenses> The optical member of the present invention can particularly include an optical lens, such as an imaging lens for a mobile phone, a smartphone, a tablet terminal, a personal computer, a digital camera, a video camera, an in-vehicle camera, a surveillance camera, or the like, or a sensing camera such as a TOF camera.

[0060] When the optical lens of the present invention is manufactured by injection molding, molding is preferably performed under conditions of a cylinder temperature of 230 to 350°C and a mold temperature of 70 to 180°C. More preferably, molding is performed under conditions of a cylinder temperature of 250 to 300°C and a mold temperature of 80 to 170°C. If the cylinder temperature is higher than 350°C, the thermoplastic 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 a thermoplastic 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 sufficiently transfer the shape imprinted on the mold.

[0061] The optical lens of the present invention is preferably implemented as an aspherical lens, if necessary. Since a single aspherical lens can substantially eliminate spherical aberration, it is not necessary 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.

[0062] Furthermore, because the thermoplastic 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 shape of the lens is preferably a meniscus lens, with one side convex and the other concave.

[0063] The lens made of the thermoplastic resin of the present invention can be formed by any method such as mold molding, cutting, polishing, laser processing, electrical discharge processing, etching, etc. Among these, mold molding is more preferred in terms of production costs.

[0064] The present invention will be explained in more detail in the following examples, but the present invention is not limited thereto. [Example]

[0065] The evaluation was carried out by the following method.

[0066] <Thermoplastic resin composition> JEOL JNM-ECZ400S 1 The copolymerization ratio of each thermoplastic resin was calculated by measuring 1 H NMR.

[0067] <Refractive index> A 3 mm thick test piece of each thermoplastic resin was prepared and polished, and then the refractive indexes ng (435.83 nm), nF (486.13 nm), nd (587.56 nm), and nC (656.27 nm) were measured using a Shimadzu Kalnew Precision Refractometer KPR-2000.

[0068] <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: Refractive index at a wavelength of 656.27 nm.

[0069] <θgF> The partial dispersion ratio (θgF) is calculated using the following formula from the refractive indexes at a temperature of 20° C. and wavelengths of 435.83 nm, 486.13 nm, and 656.27 nm. θgF=(ng-nF) / (nF-nC) ng: refractive index at wavelength 435.83 nm, nF: refractive index at a wavelength of 486.13 nm, nC: Refractive index at a wavelength of 656.27 nm.

[0070] <Absolute value of orientation birefringence> The thermoplastic 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)

[0071] <Glass transition temperature (Tg)> The thermoplastic resin obtained was measured at a heating rate of 20°C / min using a Discovery DSC 25Auto model manufactured by TA Instruments Japan Co., Ltd. Samples weighing 5 to 10 mg were used.

[0072] Example 1 98.67 g (0.23 mol) of 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene (hereinafter sometimes abbreviated as BPEF), 76.10 g (0.25 mol) of 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (hereinafter sometimes abbreviated as SPG), 7.76 g (0.03 mol) of 4,4'-(3,3,5-trimethylcyclohexyl) Bis(trimethylammonium methyl ester) bisphenol (hereinafter sometimes abbreviated as BisTMC), 109.25 g (0.51 mol) of diphenyl carbonate, and 62.5 μL of a 40 mmol / L aqueous solution of sodium bicarbonate (2.5 μmol of sodium bicarbonate) and 54.7 μL of a 274 mmol / L aqueous solution of tetramethylammonium hydroxide (15 μmol of tetramethylammonium hydroxide) were heated to 180°C under a nitrogen atmosphere and melted. The vacuum was then 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 mixture was stirred for a total of 3.5 hours, and the resin was removed after the reaction was completed. The copolymerization ratio of the resulting polycarbonate resin was: 1 The refractive index, Abbe number, absolute value of orientation birefringence, Tg, and θgF of the polycarbonate resin were measured by H NMR. The terminal phenolic hydroxyl group ratio of the polycarbonate resin was 0%.

[0073] <Examples 2 to 10> A polycarbonate resin was produced in the same manner as in Example 1, except that the monomer ratio was changed so that the copolymerization ratio of BPEF, SPG, and BisTMC was the ratio shown in Table 1. The copolymerization ratio, refractive index, Abbe number, absolute value of orientation birefringence, Tg, and θgF of the polycarbonate resin were evaluated. The terminal phenolic hydroxyl group ratio of the polycarbonate resin was 0%.

[0074] <Comparative Examples 1 to 4> Polycarbonate resins were produced in the same manner as in Example 1, except that the monomer ratio was changed so that the copolymerization ratio of BPEF, SPG, and BisTMC would be the ratio shown in Table 1.

[0075] <Result> The configurations and evaluation results of each of the examples and comparative examples are summarized in Table 1 below.

[0076] [Table 1]

[0077] BPEF: 9,9-bis[4-(2-hydroxyethoxy)phenyl]fluorene SPG: 3,9-bis(2-hydroxy-1,1-dimethylethyl)-2,4,8,10-tetraoxaspiro[5.5]undecane BisTMC: 4,4'-(3,3,5-trimethylcyclohexylidene)bisphenol

[0078] Examples 1 to 10 are excellent in refractive index, Abbe number, θgF, and birefringence. Comparative Example 2 corresponding to Patent Document 1 is inferior in that it has a lower Abbe number than the Examples, Comparative Examples 3 and 4 corresponding to Patent Document 2 have higher birefringence and lower θgF than the Examples, and Comparative Example 1 corresponding to Patent Document 3 has higher birefringence and lower θgF than the Examples. [Industrial Applicability]

[0079] The thermoplastic resin of the present invention can be used in optical materials, 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 for optical lenses.

Claims

1. A thermoplastic resin containing repeating units represented by formula (1), formula (2), and formula (3), wherein the repeating units represented by formula (1) account for more than 30 mol % but less than 50 mol %, and the repeating units represented by formula (3) account for 30 mol % or less. 【Chemical 1】 (In formula (1), R １ ~R ４ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms. 【Chemistry 2】 【Chemistry 3】 (In formula (3), n is in the range of 1 to 8, and R ５ and R ６ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms; R ７ represents a hydrogen atom or an alkyl group having 1 to 3 carbon atoms)

2. The thermoplastic resin according to claim 1, wherein the repeating unit of the formula (2) is 30 mol % or more and 60 mol % or less.

3. R in the formula (1) １ ~R ４ The thermoplastic resin according to claim 1 or 2, wherein is a hydrogen atom.

4. 3. The thermoplastic resin according to claim 1, wherein the repeating unit of formula (3) is a repeating unit derived from 4,4'-(3,3,5-trimethylcyclohexylidene)bisphenol.

5. The thermoplastic resin according to claim 1 or 2, which has an Abbe number of 29 to 35.

6. The absolute value of orientation birefringence is 3.7 × 10 －３ The thermoplastic resin according to claim 1 or 2, wherein:

7. The thermoplastic resin according to claim 1 or 2, having a partial dispersion ratio (θgF) of 0.615 or more.

8. An optical member comprising the thermoplastic resin according to claim 1 or 2.

9. The optical member according to claim 8, which is an optical lens.

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