Optical lens

Abstract

To provide an optical lens for vehicle lamp equipment that can suppress an occurrence of white turbidity and ensure light transmittance for a long period of time.SOLUTION: An optical lens 12 comprises a polycarbonate resin, where the content of a compound having a hydroxy group derived from polycarbonate contained in the polycarbonate resin is 0.1 ppm or more and 200 ppm or less, and the spectral transmittance at a wavelength of 320 nm is 50% or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an optical lens. [Background technology]

[0002] Polycarbonate resin (PC), a transparent synthetic resin, has excellent transparency, moldability, and mechanical properties, and is therefore used as an optical lens material in many fields, such as lenses (covers) for vehicle lighting fixtures for automobiles, motorcycles, bicycles, etc., eyeglass lenses, optical sensor covers, various liquid crystal panels, etc. However, optical lenses made of polycarbonate resin have the problem that they become cloudy, making it difficult to maintain translucency over long periods of time.

[0003] For example, Patent Document 1 discloses a lens for a vehicle lamp formed from a resin obtained by adding an anti-clouding agent to an alicyclic structure-containing thermoplastic resin. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 4099870 Summary of the Invention [Problem to be solved by the invention]

[0005] However, even if such a lens for a vehicle lamp is used, the fundamental cause of the occurrence of cloudiness is not solved, and there is a concern that the cloudiness prevention agent's effect of suppressing the occurrence of cloudiness is insufficient, making it difficult to ensure the light transmittance of the lens over a long period of time.

[0006] The present invention has been made in view of the above points, and aims to provide an optical lens that can suppress the occurrence of cloudiness and ensure translucency for a long period of time. [Means for solving the problem]

[0007] The optical lens of the present invention comprises: An optical lens using polycarbonate resin, the content of compounds having a hydroxy group derived from polycarbonate contained in the polycarbonate resin is 0.1 ppm or more and 200 ppm or less; The spectral transmittance at a wavelength of 320 nm is 50% or more. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a conceptual diagram showing an optical unit having an optical lens of the present invention. [Figure 2] FIG. 1 is a conceptual diagram showing a conventional optical lens. [Figure 3] 1 is a table summarizing the configurations of examples and comparative examples of the optical lens (molded body) of the present invention. [Figure 4] 1 is a table summarizing the results of comparison between examples and comparative examples of the optical lens (molded body) of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0009] In the following, preferred embodiments of the present invention will be described, but they may be modified and combined as appropriate. In the following description and accompanying drawings, substantially the same or equivalent parts are designated by the same reference numerals.

[0010] FIG. 1 is a conceptual diagram showing an optical unit 10 using an optical lens 12 of the present invention, and is a cross-sectional view of the optical unit 10. In this embodiment, the optical unit 10 is a vehicle lighting unit having a light-emitting device. That is, in this embodiment, the optical lens 12 is a lens for a vehicle lighting fixture. Note that the use of the optical unit 10 is not limited to vehicle headlight units, and it may also be used in lighting fixtures for vehicles other than headlights, such as automobiles and motorcycles, optical sensors, street lights, cameras, etc.

[0011] As shown in FIG. 1, the optical unit 10 includes a housing 11, a light-transmitting optical lens 12, and an optical device 13 disposed in an internal space 10A defined by the housing 11 and the optical lens 12.

[0012] The housing 11 is a housing that covers and supports a portion of the optical device 13. In detail, the housing 11 supports the optical device 13 via a fixing device (not shown). The housing 11 has a bottom wall 11A that covers the rear side of the optical device 13, and a first side wall 11B that extends parallel to the light output direction of the optical device 13 (leftward in FIG. 1), and is open at the front.

[0013] The housing 11 can be made of an elastic thermoplastic resin material such as ABS (acrylonitrile butadiene styrene) resin, PBT (polybutylene terephthalate) resin, or PP (polypropylene) resin.

[0014] The optical lens 12 is fixed to the housing 11 so as to close the opening of the housing 11. That is, the light emitted from the optical device 13 passes through the optical lens 12 and is emitted to the outside of the internal space 10A.

[0015] Polycarbonate resin is used as the material of the optical lens 12. The content of compounds having hydroxy groups derived from polycarbonate contained in the polycarbonate resin is 0.1 ppm or more and 200 ppm or less.

[0016] The content of the compound having a hydroxy group derived from polycarbonate contained in the polycarbonate resin can be measured, for example, by a derivatization method using a nuclear magnetic resonance (NMR) device. Specifically, the terminal of the hydroxy group of the polycarbonate is trimethylsilylated, and then the trimethylsilyl group is quantified by comparing with an internal standard (ethyl acetate) using a nuclear magnetic resonance device, thereby measuring the content of the compound having a hydroxy group derived from polycarbonate.

[0017] Measurements of quantitative determination of trimethylsilyl by comparison with an internal standard (ethyl acetate) using a nuclear magnetic resonance spectrometer can be carried out using an NMR spectrometer (apparatus name: AVACE NEO 400, manufactured by Bruker Japan) by comparing the integral ratio with the internal standard ethyl acetate (ethyl acetate, s, 2.0 ppm, 3H), since after derivatization of the trimethylsilyl group, it is observed at s, 0.27 ppm, 9H.

[0018] In a conventional optical lens 20 containing a large amount of compounds having hydroxyl groups derived from polycarbonate resin, when exposed to light for a long period of time, the compounds having hydroxyl groups 21 gather together through hydrogen bonding or the like to form particles, as shown in Figure 2, generating microparticle aggregates 22 having oxygen atoms. Light is then scattered by the microparticle aggregates 22, causing the optical lens to become cloudy.

[0019] On the other hand, since the polycarbonate resin used in the optical lens 12 of the present invention contains 200 ppm or less of compounds having polycarbonate-derived hydroxy groups, the formation of microparticle aggregates that occur when exposed to light for a long period of time is suppressed, and the occurrence of cloudiness in the optical lens can be suppressed.

[0020] The content of the compound having a hydroxy group derived from polycarbonate contained in the polycarbonate resin is preferably 0.5 ppm or more and 100 ppm or less.

[0021] This further suppresses the generation of microparticle aggregates, thereby further suppressing the occurrence of cloudiness in the optical lens. In other words, a positive correlation is observed between the content of the compound having a hydroxy group derived from polycarbonate contained in the polycarbonate resin and the number of microparticle aggregates generated.

[0022] The compound having a hydroxy group derived from polycarbonate is represented by, for example, the following general formulas (1) to (6).

[0023] [ka]

[0024] Among the compounds represented by the above general formulas (1) to (6), the compounds represented by the following general formulas (1) to (3) are particularly likely to form fine particle aggregates containing oxygen atoms by gathering together through hydrogen bonds or the like and forming particles when irradiated with light for a long period of time. Therefore, the content of the compounds represented by the following general formulas (1) to (3) is preferably 0.1 ppm or more and 200 ppm or less, and more preferably 0.5 ppm or more and 100 ppm or less.

[0025] [ka]

[0026] This further suppresses the formation of aggregates of fine particles, and further suppresses the occurrence of cloudiness in the optical lens.

[0027] After the optical device 13 has been turned on for 1000 hours, the optical lens 12 has fewer than 10 microparticle aggregates that are observed to be 100 nm or more and 5 μm or less in an image of a cross section of the optical path in the thickness direction of the optical lens 12 taken at 1000x magnification using a scanning electron microscope (SEM), and that are confirmed to contain oxygen atoms using energy dispersive X-ray spectrometry (EDS).

[0028] Microparticle aggregates can be observed using a scanning electron microscope, for example, by lighting a polycarbonate molded body continuously for 1000 hours with an LED white light source, cutting out a 10 μm thick slice from the cloudy area using an ultrasonic cutter and a microtome (manufactured by Yamato Koki Kogyo Co., Ltd.), and examining it under the following conditions. (Analysis conditions) Device name: JSM-IT700HR (manufactured by JEOL Ltd.) Signal: SED Incident voltage: 15.0 kV WD: 10.0 mm Magnification: ×1,000 Observation area: 128.0 x 96.0 μm Scanning current number: Srd.75.0 Scan rotation: 0.0° Vacuum mode: High Vacuum

[0029] The presence of oxygen atoms in microparticle aggregates can be confirmed by energy dispersive X-ray fluorescence analysis, for example, by illuminating a polycarbonate molded body with an LED white light source for 1000 hours continuously, cutting out a 10 μm thick slice from the cloudy area using an ultrasonic cutter and a microtome (manufactured by Yamato Koki Kogyo Co., Ltd.), and confirming the presence of oxygen atoms under the following conditions. (Analysis conditions) Device name: JSM-IT700HR (manufactured by JEOL Ltd.) Detector: EDS detector, dry SD detector Device name:EX-7412U4L2Q Method: Silicon drift type Detector area: 30mm 2 Energy resolution: 129 eV or less Detectable elements: Be~U Window: Thin polymer film Cooling method: Electronic cooling (Peltier cooling) Usable accelerating voltage: 30 kV or less Digital Processor Maximum throughput: 200kcps Interface: RS-232C

[0030] When the optical lens 12 has fewer than 10 microparticle aggregates confirmed by the above-mentioned measurement method, light scattering by the microparticle aggregates and the optical lens 12 becoming cloudy can be suppressed.

[0031] The number of microparticle aggregates observed in optical lens 12 by the above-mentioned measurement method is preferably 5 or less, and more preferably 2 or less, which can further prevent light from being scattered by the microparticle aggregates and causing optical lens 12 to become cloudy.

[0032] The optical lens 12 has a spectral transmittance (%) of 50% or more at a wavelength of 320 nm in the thickness direction. The spectral transmittance at a wavelength of 320 nm can be measured, for example, using an ultraviolet-visible spectrophotometer (device name: UV-2600i, manufactured by Shimadzu Corporation) by scanning wavelengths of 250 nm to 800 nm and using a D2 light source and a W light source.

[0033] The optical lens 12 preferably has a spectral transmittance (%) in the thickness direction at a wavelength of 320 nm of 55% or more, more preferably 60% or more, and even more preferably 65% ​​or more.

[0034] In addition, various additives such as antioxidants, plasticizers, antistatic agents, nucleating agents, flame retardants, lubricants, impact modifiers, fluorescent whitening agents, and ultraviolet absorbers may be added to the polycarbonate resin used in the optical lens 12, as long as the content of the polycarbonate resin is 95% or more.

[0035] In this embodiment, an LED light source is used as the optical device 13. However, the optical device 13 may also be a lighting unit such as a fluorescent lamp, a laser light source, or an incandescent light bulb, an optical sensor unit that emits visible light, infrared light, ultraviolet light, millimeter waves, or the like, or an optical sensor unit that detects visible light, infrared light, ultraviolet light, millimeter waves, or the like. Alternatively, a light source for an optical sensor and an optical sensor unit that detects reflected light of the light emitted from the light source for the optical sensor may also be used.

[0036] Next, the polycarbonate resin used in the optical lens 12 of the present invention and the method for manufacturing the optical lens 12 will be described.

[0037] The polycarbonate resin used in the optical lens 12 of the present invention can be produced by interfacially polymerizing a composition containing an aromatic diol compound and a carbonate precursor in the presence of an acid binder and a solvent, as shown in the chemical formula below (interfacial polymerization method).

[0038] [ka]

[0039] As shown in the above chemical formula, in this embodiment, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) was used as the aromatic diol compound, phosgene was used as the carbonate precursor, sodium hydroxide was used as the acid binder, dichloromethane was used as the solvent, and 4-methylphenol was used as the terminator.

[0040] The content of the aromatic diol compound can be 40 parts by mass or more and 80 parts by weight or less based on the total amount of the composition, and the content of the carbonate precursor can be 20 parts by weight or more and 60 parts by weight or less based on the total amount of the composition.

[0041] The interfacial polymerization of the composition was carried out in a nitrogen atmosphere (oxygen-free environment) at a polymerization temperature of 0 to 40° C. for a reaction time of several minutes to 5 hours. The pH during the reaction was maintained at 9 or higher.

[0042] In this embodiment, bisphenol A is used as the aromatic diol compound. However, other aromatic diol compounds may be used, such as 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxy-3,5-dibromophenyl)propane, 2,2-bis(4-hydroxy-3-chlorophenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)ethane, bis(4-hydroxyphenyl)methane, bis(4-hydroxyphenyl)ether, bis(4-hydroxyphenyl)sulfone, bis(4-hydroxyphenyl)sulfoxide, bis(4-hydroxyphenyl)sulfide, and bis(4-hydroxyphenyl)ketone. These aromatic diol compounds may be used alone or in any combination of two or more.

[0043] In this embodiment, phosgene is used as the carbonate precursor. However, other carbonate precursors may also be used, such as triphosgene, diphosgene, bromophosgene, dimethyl carbonate, diethyl carbonate, dibutyl carbonate, dicyclohexyl carbonate, diphenyl carbonate, ditolyl carbonate, bis(chlorophenyl)carbonate, m-cresyl carbonate, dinaphthyl carbonate, bis(diphenyl)carbonate, or bishaloformates.

[0044] In this embodiment, sodium hydroxide is used as the acid binder, but other acid binders may also be used, for example, alkali metal hydroxides such as potassium hydroxide or amine compounds such as pyridine.

[0045] In this embodiment, dichloromethane is used as the solvent, but a halogenated hydrocarbon such as chlorobenzene may also be used as the solvent.

[0046] In this embodiment, 4-methylphenol is used as the terminator, but other terminators such as 3-methylphenol, phenol, 4-propylphenol, 3-propylphenol, 1-phenylphenol, and 2-phenylphenol may also be used.

[0047] A catalyst such as a tertiary amine or a quaternary ammonium salt may be added to the composition as an additive to promote the reaction.

[0048] Although the above-mentioned method for producing the polycarbonate resin has been described as being based on the interfacial polymerization method, the polycarbonate resin may also be produced by the melt polymerization method (ester interchange method).

[0049] As an example of a method for manufacturing the optical lens 12 of the present invention from polycarbonate resin, the polycarbonate and other additives are mixed using a mixer, then extruded in an extruder to produce pellets, and the pellets are dried and then molded in an injection molding machine, thereby manufacturing the optical lens 12. [Example]

[0050] The present invention will be described in more detail below with reference to examples and comparative examples. However, the present invention is not limited to these examples. The synthesis of the components was carried out based on technical literature (Molecules 2010, 15, 3661-3682, pp. 3664, 3677).

[0051] [Synthesis of intermediates] First, 20.0 g of bisphenol A (FUJIFILM Wako Pure Chemical Corporation), 4.16 g of pyridine (FUJIFILM Wako Pure Chemical Corporation), 0.16 g of 4-DMAP (FUJIFILM Wako Pure Chemical Corporation), and 300 g of dry THF (Junsei Chemical Co., Ltd.) were added to a 500 mL three-neck flask, cooled to 0 °C, and stirred. 4.14 g of methyl chloroformate (Tokyo Chemical Industry Co., Ltd.) was added dropwise over 30 minutes, and the mixture was stirred at 0 °C for 1 hour and then at 25 °C for 1 hour. After the reaction was completed, the mixture was poured into a 2000 mL beaker (containing 600 mL of purified water) to obtain a white precipitate. This white precipitate was collected by suction filtration. It was then washed three times with 300 mL of 10% aqueous sodium carbonate solution, followed by 300 mL of purified water. Vacuum drying at 40 °C for 15 hours yielded 15 g of the intermediate.

[0052] [ka]

[0053] [Synthesis Example 1] 10 g of the intermediate, 0.1 g of Orgatix TC-400 (Matsumoto Fine Chemical Co., Ltd.) as a catalyst, and 25.0 g of p-tert-butylphenol (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a 200 mL three-neck flask and refluxed at 120°C for 3 hours. After the reaction, the disappearance of the methyl group peak of the intermediate was confirmed by NMR, yielding a crude product. After distilling off the tert-butylphenol, the product was recrystallized from ethanol to obtain 5 g of the component of Synthesis Example 1.

[0054] [ka]

[0055] [Synthesis Example 2] 10 g of the intermediate, 0.1 g of Orgatix TC-400 (Matsumoto Fine Chemical Co., Ltd.) as a catalyst, and 25.0 g of bisphenol A (Fujifilm Wako Pure Chemical Industries, Ltd.) were added to a 200 mL three-neck flask and refluxed at 170°C for 3 hours. After the reaction, the disappearance of the methyl group peak of the intermediate was confirmed by NMR, yielding a crude product. After removing bisphenol A by washing with methanol, the product was repeatedly washed with methanol to obtain 5 g of the component of Synthesis Example 2.

[0056] [ka]

[0057] [Synthesis Example 3] To a 100 mL three-neck flask were added 3 g of the component of Synthesis Example 1 and 5 g of aluminum chloride (Tokyo Chemical Industry Co., Ltd.), and 50 mL of THF was added. This was reacted for 5 hours at 60°C to obtain a crude product. The obtained crude product was purified by silica gel chromatography (hexane / ethyl acetate) to obtain 1 g of the component of Synthesis Example 3.

[0058] [ka]

[0059] Example 1 Polycarbonate resin pellets (product name: Iupilon ML-300, Mitsubishi Engineering-Plastics Corporation) were mixed with 100 ppm of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate (product name: Irganox 1076, manufactured by BASF Japan Ltd.) as an antioxidant, 150 ppm of the components of Synthesis Example 1, 150 ppm of the components of Synthesis Example 2, and 150 ppm of the components of Synthesis Example 3, and molded using an injection molding machine to obtain a molded article (optical lens) of Example 1, measuring 100 mm x 80 mm and 3 mm thick. The configurations of Examples 1 to 3 and Comparative Example 1 are summarized in FIG. 3.

[0060] Example 2 Polycarbonate resin pellets (product name: Iupilon ML-300, Mitsubishi Engineering-Plastics Corporation) were mixed with 100 ppm of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate (product name: Irganox 1076, manufactured by BASF Japan Ltd.) as an antioxidant, 50 ppm of the components of Synthesis Example 1, 50 ppm of the components of Synthesis Example 2, and 50 ppm of the components of Synthesis Example 3, and molded using an injection molding machine to obtain a molded article (optical lens) of Example 2 measuring 100 mm × 80 mm and 3 mm in thickness.

[0061] Example 3 Polycarbonate resin pellets (product name: Iupilon ML-300, Mitsubishi Engineering-Plastics Corporation) were mixed with 100 ppm of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate (product name: Irganox 1076, manufactured by BASF Japan Ltd.) as an antioxidant, 20 ppm of the components of Synthesis Example 1, 20 ppm of the components of Synthesis Example 2, and 20 ppm of the components of Synthesis Example 3, and molded using an injection molding machine to obtain a molded article (optical lens) of Example 3 measuring 100 mm × 80 mm and 3 mm in thickness.

[0062] Polycarbonate resin pellets (product name: Makrolon 2205, manufactured by Covestro Japan Co., Ltd.) were mixed with 100 ppm of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate (product name: Irganox 1076, manufactured by BASF Japan Co., Ltd.) as an antioxidant, 200 ppm of the components of Synthesis Example 1, 200 ppm of the components of Synthesis Example 2, and 200 ppm of the components of Synthesis Example 3, and molded using an injection molding machine to obtain a molded article (optical lens) of Comparative Example 1 measuring 100 mm × 80 mm and 3 mm thick.

[0063] (Evaluation of hydroxy group content) The compacts of Examples 1 to 3 and Comparative Example 1 were each placed in a 50-mL two-neck flask with 2 mL of chloroform and stirred with a stirrer for 1 hour to dissolve the compacts. 0.5 mL of hexamethyldisilazane and 0.2 mL of trimethylchlorosilane were added, and the mixture was allowed to react at 70°C for 2 hours to convert the hydroxyl groups to trimethylsilyl groups. The resulting derivatives were quantified using a nuclear magnetic resonance spectrometer by comparing their concentrations in deuterated chloroform with 0.28 ppm and 2.0 ppm of ethyl acetate, and evaluated on a 5-point scale (A to E).

[0064] After derivatization of the trimethylsilyl group, the trimethylsilyl was quantified by comparing it with the internal standard (ethyl acetate) using a nuclear magnetic resonance spectrometer. Since it was observed at s, 0.27 ppm, 9H, it was quantified using an NMR spectrometer (instrument name: AVACE NEO 400, manufactured by Bruker Japan) by comparing the integral ratio with the internal standard ethyl acetate, s, 2.0 ppm, 3H.

[0065] The quantification of octadecyl 3-(3,5-di-tert-butyl-4-hydroxyphenyl)propanoate (product name: Irganox 1076, manufactured by BASF Japan Ltd.), an antioxidant having a hydroxy group, was carried out after confirming that it was not derivatized to a trimethylsilyl group by the tert-butyl group adjacent to the ortho position.

[0066] The evaluation was as follows: A: the hydroxy group content was 0.001 mmol / g or more and 0.003 mmol / g or less; B: the hydroxy group content was 0.003 mmol / g or more and less than 0.005 mmol / g; C: the hydroxy group content was 0.005 mmol / g or more and less than 0.008 mmol / g; D: the hydroxy group content was 0.008 mmol / g or more and less than 0.01 mmol / g; and E: the hydroxy group content was 0.01 mmol / g or more. Figure 4 shows the evaluation results of the hydroxy group content for Examples 1 to 3 and Comparative Example 1. The values ​​in parentheses in Figure 4 are actual measured values.

[0067] (Evaluation of hydroxyl group content in ppm) The quantitative value obtained in the evaluation of the hydroxy group content described above was multiplied by 17 hydroxy groups to obtain the hydroxy group content in ppm, which was then evaluated on a 5-point scale from A to E. The evaluation was carried out as follows: A: the hydroxy group content was 10 ppm or more and less than 40 ppm; B: the hydroxy group content was 40 ppm or more and less than 80 ppm; C: the hydroxy group content was 80 ppm or more and less than 120 ppm; D: the hydroxy group content was 120 ppm or more and less than 160 ppm; and E: the hydroxy group content was 160 ppm or more. Figure 4 shows the evaluation results of the hydroxy group content in ppm for Examples 1 to 3 and Comparative Example 1. The values ​​in parentheses in Figure 4 are actual measured values.

[0068] (Evaluation of the number of particle aggregates containing oxygen atoms) Each of the molded articles of Examples 1 to 3 and Comparative Example 1 was continuously irradiated with light having a wavelength of 440 nm emitted from an LED light source for 1,000 hours. Next, using a bench circular saw (device name: K210, manufactured by Hozan Corporation), each molded article was cut so that a cross section along the optical path of the emitted light was revealed. Next, each cut molded article was sliced ​​into 10 μm-thick slices using a microtome. Next, each slice was subjected to energy dispersive X-ray fluorescence analysis (EDS) under the following conditions to confirm the presence of microparticle aggregates containing oxygen atoms. (Analysis conditions) Device name: JSM-IT700HR (manufactured by JEOL Ltd.) Detector: EDS detector, dry SD detector Device name:EX-7412U4L2Q Method: Silicon drift type Detector area: 30mm 2 Energy resolution: 129 eV or less Detectable elements: Be~U Window: Thin polymer film Cooling method: Electronic cooling (Peltier cooling) Usable accelerating voltage: 30 kV or less Digital Processor Maximum throughput: 200kcps Interface: RS-232C

[0069] Next, each slice was platinum-coated, and the microparticle aggregates were observed using a scanning electron microscope (SEM) under the following conditions: The number of microparticle aggregates that were confirmed to contain oxygen atoms by energy dispersive X-ray fluorescence analysis and were 100 nm to 5 μm in size was observed and evaluated on a 5-level scale (A to E). (Analysis conditions) Device name: JSM-IT700HR (manufactured by JEOL Ltd.) Signal: SED Incident voltage: 15.0 kV WD: 10.0 mm Magnification: ×1,000 Observation area: 128.0 x 96.0 μm Scanning current number: Srd.75.0 Scan rotation: 0.0° Vacuum mode: High Vacuum

[0070] The evaluation was as follows: when the presence of oxygen atoms was confirmed by energy dispersive X-ray fluorescence analysis and the number of microparticle aggregates having a size of 100 nm or more and 5 μm or less was 2 or less, it was rated A; when the number was 3 or more but less than 5, it was rated B; when the number was 5 or more but less than 10, it was rated C; when the number was 10 or more but less than 15, it was rated D; and when the number was 15 or more, it was rated E. Figure 4 shows the evaluation results of the number of microparticle aggregates having oxygen atoms for Examples 1 to 3 and Comparative Example 1. The values ​​in parentheses in Figure 4 are actual measured values.

[0071] (Evaluation of spectral transmittance at a wavelength of 320 nm) The spectral transmittance (%) at a wavelength of 320 nm in the thickness direction of each of the molded articles of Examples 1 to 3 and Comparative Example 1 was measured using an ultraviolet-visible spectrophotometer (device name: UV-2600i, manufactured by Shimadzu Corporation). Measurements were performed by scanning wavelengths of 250 nm to 800 nm using a D2 light source and a W light source. The spectral transmittance (%) at a wavelength of 320 nm was then evaluated on a five-level scale of A to E.

[0072] The evaluation was carried out as follows: when the spectral transmittance at a wavelength of 320 nm was 65% or more and less than 90%, it was rated as A; when it was 60% or more and less than 65%, it was rated as B; when it was 55% or more and less than 60%, it was rated as C; when it was 50% or more and less than 55%, it was rated as D; and when it was less than 50%, it was rated as E. Figure 4 shows a summary of the evaluation results of the spectral transmittance of Examples 1 to 3 and Comparative Example 1. The values ​​in parentheses in Figure 4 are actual measured values.

[0073] 4, in Examples 1 to 3, which are molded articles having a hydroxy group content of 100 ppm or less, the number of microparticle aggregates having oxygen atoms confirmed in the evaluation of the number of microparticle aggregates was less than 10, and it is clear that the occurrence of cloudiness in the molded article can be suppressed over a long period of time. Furthermore, the molded articles of Examples 1 to 3 have a spectral transmittance of 50% or more, which also clearly shows that excellent light transmittance can be ensured.

[0074] Furthermore, as is clear from the results of Examples 2 and 3, in the molded body having a hydroxy group content of 50 ppm or less, the number of microparticle aggregates having oxygen atoms confirmed in the evaluation of the number of microparticle aggregates was less than 5, and it is clear that the occurrence of cloudiness in the molded body can be further suppressed.Furthermore, the molded bodies of Examples 2 and 3 also have a spectral transmittance of 60% or more, which clearly indicates that superior light transmittance can be ensured.

[0075] Furthermore, as is clear from the results of Example 3, in the molded product having a hydroxy group content of 40 ppm or less, the number of microparticle aggregates having oxygen atoms confirmed in the evaluation of the number of microparticle aggregates was less than two, which clearly indicates that the occurrence of cloudiness in the molded product can be further suppressed.Furthermore, the molded product of Example 3 has a spectral transmittance of 75% or more, which clearly indicates that even better light transmittance can be ensured for a long period of time.

[0076] In contrast, in Comparative Example 1, which is a molded product having a hydroxy group content of 250 ppm or more, 15 microparticle aggregates having oxygen atoms were confirmed in the evaluation of the number of microparticle aggregates having oxygen atoms, which clearly indicates that the occurrence of cloudiness in the molded product cannot be sufficiently suppressed.Furthermore, the molded product of Comparative Example 1 has a spectral transmittance of less than 50%, which clearly indicates that sufficient translucency cannot be ensured.

[0077] As described above, the optical lens 12 of the present invention can suppress the occurrence of cloudiness and ensure translucency for a long period of time. [Explanation of symbols]

[0078] 10 Optical unit 11. Housing 12 Optical Lenses 13 Optical equipment

Claims

1. An optical lens using polycarbonate resin, the content of a compound having a hydroxy group derived from polycarbonate contained in the polycarbonate resin is 0.1 ppm or more and 200 ppm or less; An optical lens having a spectral transmittance of 50% or more at a wavelength of 320 nm.

2. 10. The optical lens according to claim 1, An optical lens in which the content of the compound having a hydroxy group is 0.5 ppm or more and 100 ppm or less.

3. 10. The optical lens according to claim 1, The optical lens contains at least one of the compounds having a hydroxy group represented by each of the following general formulas (1) to (3): 【Chemistry 1】

4. 2. The optical lens according to claim 1, which is used as a lens for a vehicle lamp unit having a light emitting device.

5. An optical lens using polycarbonate resin, An optical lens in which, after 1000 hours of lighting, a cross section of the optical path in the thickness direction of the optical lens is photographed at 1000x magnification using a scanning electron microscope (SEM), and the number of microparticle aggregates that are observed to be 100 nm or more and 5 μm or less and that are confirmed to contain oxygen atoms using energy dispersive X-ray spectrometry (EDS) is less than 10.

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