Optical lens, method for manufacturing the same, and inspection method

Abstract

To provide an optical lens that suppresses the occurrence of clouding and can maintain transmittance over a long period of time. [Solution] An optical lens 12 formed from polycarbonate resin pellets, wherein the optical lens 12 has a transmittance of 65% or more and 98% or less of chloroform for light with a wavelength of 310 nm after being dissolved in 5 wt% chloroform, and / or a transmittance of 77% or more and 98% or less of chloroform for light with a wavelength of 320 nm after being dissolved in 5 wt% chloroform.

Description

Technical Field

[0001] The present invention relates to an optical lens, a method for manufacturing the same, and a method for inspecting the same.

Background Art

[0002] Polycarbonate resin (PC), which is a transparent synthetic resin, is excellent in transparency, moldability, and mechanical properties. Therefore, it is used as a material for optical lenses in many fields, such as lenses for vehicle lamps for automobiles, motorcycles, bicycles, etc., spectacle lenses, covers for optical sensors, and various liquid crystal panels. However, there has been a problem that an optical lens made of polycarbonate resin becomes cloudy when exposed to emitted light for a long period of time, and it is difficult to maintain the transmittance over a long period.

[0003] For example, Patent Document 1 discloses a lens for a vehicle lamp formed from a resin containing an anti-clouding agent in an alicyclic structure-containing thermoplastic resin.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, even when such a lens for a vehicle lamp is used, the root cause of clouding has not been fundamentally solved. Due to insufficient content or insufficient function of the anti-clouding agent, the effect of suppressing clouding is insufficient, and there has been a concern that it is difficult to maintain the transmittance of the lens over a long period.

[0006] An object of the present invention has been made in view of the above points, and an object thereof is to provide an optical lens capable of suppressing the occurrence of clouding and maintaining the transmittance over a long period. [Means for solving the problem]

[0007] The optical lens of the present invention An optical lens formed from polycarbonate resin pellets, The optical lens has a transmittance of 65% to 98% of light with a wavelength of 310 nm after being dissolved in 5 wt% chloroform, and / or a transmittance of 77% to 98% of light with a wavelength of 320 nm after being dissolved in 5 wt% chloroform. [Brief explanation of the drawing]

[0008] [Figure 1A] This is a conceptual diagram showing an example of an optical unit having an optical lens according to the present invention. [Figure 1B] This is a conceptual diagram showing an example of a modified optical unit having an optical lens according to the present invention. [Figure 2] This graph shows the transmittance of chloroform after dissolving the optical lens of the present invention in 5 wt% chloroform. [Figure 3] This graph shows the transmittance of polycarbonate resin pellets used in the manufacture of the optical lens of the present invention after they have been dissolved in 5 wt% chloroform. [Figure 4] This graph shows the correlation between the transmittance of light at a wavelength of 300-320 nm between a 5 wt% chloroform solution of the optical lens of the present invention and a 5 wt% chloroform solution of polycarbonate resin pellets used in the manufacture of the optical lens of the present invention. [Figure 5] This table summarizes the comparison results between examples and comparative examples of the optical lens of the present invention. [Figure 6] This graph shows the rate of change in luminous intensity over time during the evaluation of the long-term transmittance maintenance performance of the optical lenses of the present invention in examples and comparative examples. [Modes for carrying out the invention]

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

[0010] Figure 1A is a conceptual diagram showing an optical unit 10 having an optical lens 12 according to the present invention, and is a cross-sectional view of the optical unit 10. As shown in Figure 1A, the optical unit 10 comprises a housing 11, a light-transmitting optical lens 12, and an optical instrument 13 disposed in an internal space 10A defined by the housing 11 and the optical lens 12.

[0011] In this embodiment, the optical unit 10 is a vehicle lighting unit having a light-emitting device. In other words, in this embodiment, the optical lens 12 is a cover for the vehicle lighting unit. In addition to being a cover for the vehicle lighting unit, the optical lens 12 may also serve as a cover to protect the optical equipment 13 from damage, such as an optical sensor cover, or as an optical lens 22 positioned inside the optical unit 10 in the direction of light emission from the optical equipment 13 to control the light from the optical equipment 13, as shown in Figure 1B.

[0012] The housing 11 is a casing that covers and supports a portion of the optical instrument 13. More specifically, the housing 11 supports the optical instrument 13 via a fixing device (not shown). The housing 11 has a lower wall 11A that covers the rear side of the optical instrument 13 and a first side wall 11B that extends parallel to the direction of light emission from the optical instrument 13 (to the left in Figure 1A), and is open at the front.

[0013] For the housing 11, for example, an elastic thermoplastic resin material such as ABS (acrylonitrile butadiene styrene) resin, PBT (polybutylene terephthalate) resin, or PP (polypropylene) resin can be used.

[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] The optical lens 12 is formed from a polycarbonate resin containing an antioxidant. The content rate of the antioxidant in the polycarbonate resin is 0.01% by mass or more and 0.1% by mass or less.

[0016] FIG. 2 is a graph showing the transmittance of chloroform after dissolving the optical lens of Example 1 described in the examples described later in 5 wt% chloroform. As shown in FIG. 2, for the optical lens 12, the transmittance of chloroform for light with a wavelength of 310 nm after being dissolved in 5 wt% chloroform is 65% or more and 98% or less (R1).

[0017] The transmittance of chloroform for light with a wavelength of 310 nm after being dissolved in 5 wt% chloroform was determined by dissolving 250 mg of the optical lens in 3.4 mL of a 5 wt% chloroform solution and measuring under the following analysis conditions.

[0018] (Analysis conditions) Device name: Spectrophotometer (manufactured by Shimadzu Corporation) Measurement wavelength range: 240 - 500 nm

[0019] Since the transmittance of chloroform for light with a wavelength of 310 nm after the optical lens 12 is dissolved in 5 wt% chloroform is 65% or more and 98% or less, the transmittance can be maintained over a long period.

[0020] One reason for the decrease in the transmittance of an optical lens when the optical device 13 is lit for a long period of time is that components represented by the following general formulas (1) to (3) cause clouding due to prolonged exposure to light. The light absorption wavelength band of these clouding-causing components includes wavelengths of 310 to 320 nm. Therefore, by measuring the transmittance of the optical lens at wavelengths of 310 nm to 320 nm, a low transmittance indicates that the optical lens contains a large amount of these clouding-causing components, while a high transmittance indicates that the optical lens contains little or no of these components. Thus, by setting the transmittance of the optical lens at wavelengths of 310 to 320 nm to a predetermined value or higher, it becomes possible to suppress clouding due to prolonged light irradiation and maintain transmittance.

[0021] [ka]

[0022] In detail, using the initial luminous intensity of light emitted from the optical lens when the optical device has been lit for 0 hours as the baseline (0%), the rate of change in the luminous intensity of light emitted from the optical lens after 3000 hours of continuous operation of the optical device can be reduced to less than -15.0%.

[0023] Furthermore, the optical lens 12 may have a transmittance of 77% to 98% (R2) of chloroform with a wavelength of 320 nm after dissolving in 5 wt% chloroform. This allows the transmittance to be maintained over a long period of time, achieving the same effect as when the transmittance of chloroform with a wavelength of 310 nm after dissolving in 5 wt% chloroform is 65% to 98%.

[0024] Furthermore, in order to maintain transmittance over a long period of time, the transmittance of the chloroform after dissolving it in 5 wt% chloroform with light at a wavelength of 310 nm may be 65% or more and 98% or less, and the transmittance of the chloroform after dissolving it in 5 wt% chloroform with light at a wavelength of 320 nm may be 77% or more and 98% or less.

[0025] The optical lens 12 preferably has a transmittance of 77% to 98% and more preferably 80% to 98% of chloroform when light with a wavelength of 310 nm is dissolved in 5 wt% chloroform. When the transmittance is 77% to 98%, the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the optical device can be kept to less than -9.5%, when the luminous intensity of the light emitted from the optical lens is used as a reference when the optical device is lit for 0 hours. When the transmittance is 80% to 98%, the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the optical device can be kept to less than -5.0%, when the luminous intensity of the light emitted from the optical lens is used as a reference when the optical device is lit for 0 hours.

[0026] The optical lens 12 preferably has a transmittance of 77% to 98% and more preferably 80% to 98% of chloroform when light with a wavelength of 320 nm is dissolved in 5 wt% chloroform. When the transmittance is 77% to 98%, the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the optical device can be kept to less than -9.5%, when the luminous intensity of the light emitted from the optical lens is used as a reference when the optical device is lit for 0 hours. When the transmittance is 80% to 98%, the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the optical device can be kept to less than -5.0%, when the luminous intensity of the light emitted from the optical lens is used as a reference when the optical device is lit for 0 hours.

[0027] Furthermore, within the range where the polycarbonate resin content used in the optical lens 12 is 95% or more, various additives such as plasticizers, antistatic agents, nucleating agents, flame retardants, lubricants, impact reinforcers, fluorescent whitening agents, and ultraviolet absorbers may be added.

[0028] The optical device 13 is an LED light source. The optical device 13 may also be a lighting unit such as a fluorescent lamp, laser light source, or incandescent light bulb; an optical sensor unit that emits visible light, infrared light, ultraviolet light, or millimeter waves; or an optical sensor unit that detects visible light, infrared light, ultraviolet light, or millimeter waves. Alternatively, an optical sensor with a light source and an optical sensor unit that detects the reflected light emitted from the light source of the optical sensor may be used.

[0029] Next, the polycarbonate resin used in the manufacture of the optical lens 12 of the present invention and the method for manufacturing the optical lens 12 will be described.

[0030] The polycarbonate resin used in the optical lens 12 of the present invention can be produced by interfacial polymerization of 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).

[0031] [ka]

[0032] As shown in the chemical formula above, in this embodiment, 2,2-bis(4-hydroxyphenyl)propane (bisphenol A) was used as the aromatic diol compound, phosgene as the carbonate precursor, sodium hydroxide as the acid binder, and dichloromethane as the solvent. In addition, 4-methylphenol was used as the inhibitor.

[0033] The content of aromatic diol compounds can be 40 parts by mass or more and 80% by weight or less of the total amount of the composition. The content of carbonate precursors can be 20% by weight or more and 60% by weight or less of the total amount of the composition.

[0034] Interfacial polymerization of the composition was carried out under a nitrogen atmosphere (oxygen-free environment), with polymerization temperatures ranging from 0°C to 40°C and reaction times from several minutes to 5 hours. The pH was maintained above 9 during the reaction.

[0035] In this embodiment, bisphenol A was used as the aromatic diol compound, but other aromatic diol compounds 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 may also be used. Furthermore, these aromatic diol compounds may be used individually or in combination of any two or more.

[0036] In this embodiment, phosgene was used as the carbonate precursor, but other carbonate precursors 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 bishaloformate may also be used.

[0037] In this embodiment, sodium hydroxide was used as the acid binder, but other substances such as alkali metal hydroxides like potassium hydroxide or amine compounds like pyridine may also be used as the acid binder.

[0038] In this embodiment, dichloromethane was used as the solvent, but other solvents such as halogenated hydrocarbons like chlorobenzene may also be used.

[0039] In this embodiment, 4-methylphenol was used as the inhibitor, but other inhibitors such as 3-methylphenol, phenol, 4-propylphenol, 3-propylphenol, 1-phenylphenol, 2-phenylphenol may also be used.

[0040] Furthermore, catalysts such as tertiary amines or quaternary ammonium salts may be added to the composition as additives to accelerate the reaction.

[0041] The polycarbonate resin obtained by the above manufacturing method and an additive containing an antioxidant were mixed using a mixer, and then extruded using an extruder to produce polycarbonate resin pellets. After drying the polycarbonate resin pellets, the optical lens 12 of the present invention was manufactured by injection molding using an injection molding machine.

[0042] In this way, by manufacturing an optical lens from polycarbonate resin pellets, the antioxidant content of the polycarbonate resin is higher than that of the optical lens, and the difference in content is less than 50%. In other words, the manufacturing method of the optical lens 12 of the present invention includes a step of injection molding a polycarbonate resin such that the antioxidant content is higher than that of the optical lens, and the difference in antioxidant content is less than 50%.

[0043] By using such polycarbonate resin pellets in the manufacture of optical lenses, the antioxidant inactivates peroxides or captures radicals, thereby suppressing clouding of the optical lenses and maintaining transmittance over a long period of time.

[0044] The antioxidants incorporated into the polycarbonate resin are not particularly limited; for example, sulfur-based, phosphorus-based, or phenol-based antioxidants can be used.

[0045] Figure 3 is a graph showing the transmittance of polycarbonate resin pellets used in the manufacture of the optical lens of Example 1 described in the Examples below, after dissolving them in 5 wt% chloroform. As shown in Figure 3, the polycarbonate resin pellets obtained by the above manufacturing method have a transmittance of 83% to 98% (R3) of light at a wavelength of 310 nm after dissolving them in 5 wt% chloroform.

[0046] The transmittance of chloroform at a wavelength of 310 nm after dissolving polycarbonate resin pellets in 5 wt% chloroform was determined by dissolving 250 mg of polycarbonate resin pellets in 3.4 mL of 5 wt% chloroform solution and measuring under the following analytical conditions.

[0047] (Analysis conditions) Device name: Spectrophotometer (manufactured by Shimadzu Corporation) Measurement wavelength range: 240-500nm

[0048] Furthermore, as shown in Figure 3, the polycarbonate resin pellets obtained by the above manufacturing method have a transmittance of 92% to 98% (R4) of chloroform at a wavelength of 320 nm after being dissolved in 5 wt% chloroform.

[0049] Figure 4 is a graph showing the correlation between the chloroform solution of the optical lens in Example 1, described in the Examples below, and the chloroform solution of the polycarbonate resin pellets used in the manufacture of the optical lens, in terms of light transmittance at wavelengths of 300, 310, and 320 nm. As shown in Figure 4, the chloroform solution of the polycarbonate resin pellets and the chloroform solution of the optical lens show a high correlation in terms of light transmittance (%) at wavelengths of 300-320 nm. Therefore, by using polycarbonate resin pellets that have a high transmittance of chloroform at a wavelength of 310 nm after being dissolved in 5 wt% chloroform in the manufacture of the optical lens, it is possible to manufacture an optical lens that has a high transmittance of chloroform at a wavelength of 310 nm after being dissolved in 5 wt% chloroform.

[0050] Next, we will explain the inspection method for evaluating the transmittance maintenance performance of optical lenses. As mentioned above, when the illumination time of the optical device 13 is prolonged, one example of the cause of a decrease in the transmittance of the optical lens is that components represented by the following general formulas (1) to (3) cause clouding due to prolonged exposure to light. The light absorption wavelength band of these clouding-causing components includes wavelengths of 310 to 320 nm. Therefore, by measuring the transmittance of the optical lens to light with wavelengths of 310 nm to 320 nm, if the transmittance is low, it can be seen that the optical lens contains a large amount of the clouding-causing components, and if the transmittance is high, it can be seen that the optical lens contains little or no of the clouding-causing components. Thus, by setting the transmittance of the optical lens to light with wavelengths of 310 to 320 nm to a predetermined value or higher, it becomes possible to inspect whether clouding due to prolonged light irradiation can be suppressed and transmittance can be maintained.

[0051] [ka]

[0052] Based on the above, the optical lens 12 can maintain its transmittance over a long period of time because the transmittance of chloroform at a wavelength of 310 nm after dissolving it in 5 wt% chloroform is between 65% and 98%. Therefore, the long-term transmittance maintenance performance of the optical lens can be evaluated by measuring the transmittance of chloroform at a wavelength of 310 nm after dissolving the optical lens 12 in 5 wt% chloroform.

[0053] For example, an optical lens that has been confirmed to have a transmittance of 65% to 98% of chloroform when dissolved in 5 wt% chloroform and emitting light at a wavelength of 310 nm, can be evaluated as having excellent long-term transmittance maintenance performance. This is because, when the luminous intensity of the light emitted from the optical lens during 0 hours of continuous operation of the optical device is taken as the baseline (0%), the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the optical device is less than -15.0%.

[0054] Furthermore, the wavelength of light used when testing the transmittance maintenance performance of the optical lens 12 may be 320 nm. Also, as described above, there is a high correlation in the transmittance (%) of light with a wavelength of 300-320 nm between the chloroform solution of polycarbonate resin pellets and the chloroform solution of optical lenses manufactured using said polycarbonate resin pellets. Therefore, the transmittance maintenance performance of optical lenses manufactured from said polycarbonate resin may be tested by measuring the transmittance of said chloroform with a wavelength of 300 nm-320 nm after dissolving polycarbonate resin pellets in 5 wt% chloroform. [Examples]

[0055] 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.

[0056] [Example 1] By adding 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, along with additives intended to improve processability and fluidity, and molding the mixture in an injection molding machine, a molded body (optical lens) of Example 1, with a thickness of 3 mm and dimensions of 100 mm x 80 mm, was obtained. Note that the content of components causing clouding in the molded body varies depending on the additives contained in the molded body.

[0057] [Example 2] By adding 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, along with additives intended to improve processability and fluidity, and molding them in an injection molding machine, a molded body (optical lens) of Example 2 with a thickness of 3 mm and dimensions of 100 mm x 80 mm was obtained.

[0058] [Example 3] By adding 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, along with additives intended to improve processability and fluidity, and molding them in an injection molding machine, a molded body (optical lens) of Example 3 with a thickness of 3 mm and dimensions of 100 mm x 80 mm was obtained.

[0059] [Example 4] By adding 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, along with additives intended to improve processability and fluidity, and molding them in an injection molding machine, a molded body (optical lens) of Example 3 with a thickness of 3 mm and dimensions of 100 mm x 80 mm was obtained.

[0060] [Example 5] By adding 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, along with additives intended to improve processability and fluidity, and molding the mixture in an injection molding machine, a molded body (optical lens) of Example 5 with a thickness of 3 mm and dimensions of 100 mm x 80 mm was obtained.

[0061] [Comparative Example 1] By adding 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, along with additives intended to improve processability and fluidity, and molding the mixture in an injection molding machine, a molded body (optical lens) of Comparative Example 1, with a thickness of 3 mm and dimensions of 100 mm x 80 mm, was obtained.

[0062] (Permeability of chloroform solution) Each of the molded bodies from Examples 1-5 and Comparative Example 1 was placed in a 50 mL two-necked flask with 3.4 mL of 5 wt% chloroform and stirred with a stirring bar for 1 hour to dissolve the molded bodies. Subsequently, the transmittance (%) of the chloroform solution of the molded bodies at a wavelength of 310 nm was determined by measurement under the following analytical conditions. The evaluation was as follows: A if the transmittance was 80% or higher, B if the transmittance was 75% or higher but less than 80%, C if the transmittance was 70% or higher but less than 75%, D if the transmittance was 65% or higher but less than 70%, and E if the transmittance was less than 65%. Figure 5 summarizes the evaluation results of the transmittance of the chloroform solutions from Examples 1-5 and Comparative Example 1. The values ​​in parentheses in Figure 5 are the measured values.

[0063] (Analysis conditions) Device name: Spectrophotometer (manufactured by Shimadzu Corporation) Measurement wavelength range: 240-500nm

[0064] (Reduction rate of antioxidants) The molded articles of Examples 1-5 and Comparative Example 1, along with the polycarbonate resin pellets used to manufacture each molded article, were cut into 0.1g pieces and dissolved in 10mL of tetrahydrofuran. This solution was added dropwise to 100mL of acetonitrile to precipitate the polymer, then filtered and the solution was collected. The amount of antioxidant in this solution was then qualitatively and quantitatively determined by measuring it using a Waters LC-TOFMS (acetonitrile / water). From these qualitative and quantitative results, the difference in antioxidant content between each molded article and the polycarbonate resin pellets used to manufacture each molded article was evaluated as the antioxidant reduction rate (%). The evaluation was categorized as follows: A if the antioxidant reduction rate was less than 8%, B if it was 8% or more but less than 15%, C if it was 15% or more but less than 30%, D if it was 30% or more but less than 50%, and E if it was 50% or more. Figure 5 summarizes the evaluation results of the antioxidant reduction rate for Examples 1-5 and Comparative Example 1.

[0065] The antioxidant reduction rate of the molded article in Example 1 was 45%, the antioxidant reduction rate of the molded article in Example 2 was 48%, the antioxidant reduction rate of the molded article in Example 3 was 7%, and the antioxidant reduction rate of the molded article in Example 4 was 20%.

[0066] (Evaluation of long-term transmittance maintenance performance) Each of the molded bodies of Examples 1 to 5 and Comparative Example 1 was continuously irradiated with light emitted from an LED light source for 3000 hours. The long-term transmittance maintenance performance was evaluated by determining the rate of change (%) of the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous LED light emission, using the initial luminous intensity of the light emitted from each molded body at the start of LED light emission as the baseline (0%). The evaluation criteria were as follows: an A rating was given if the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the LED light source was between -1.0% and less than -5.0%; a B rating was given if the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the LED light source was between -5.0% and less than -9.5%; a C rating was given if the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the LED light source was between -9.5% and less than -15.0%; and a D rating was given if the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the LED light source was -15.0% or more. Figure 5 summarizes the evaluation results of the long-term transmittance maintenance performance of Examples 1 to 5 and Comparative Example 1. Figure 6 shows the rate of change in luminous intensity over time during the evaluation of the long-term transmittance maintenance performance of Examples 1 to 3, 5 and Comparative Example 1.

[0067] As shown in Figure 5, in Examples 1 to 5, which are molded bodies with a chloroform dissolution transmittance of 70% or more, the evaluation of long-term transmittance maintenance performance shows that the rate of change in the luminous intensity of light emitted from the optical lens is less than -15.0% after 3000 hours of continuous lighting of the LED light source, indicating that the transmittance can be maintained over a long period of time.

[0068] As is clear from the results of Examples 1 to 3, in Examples 1 to 3, where the transmittance of the chloroform solution is 77% or higher, the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the LED light source is less than -9.5% in the evaluation of long-term transmittance maintenance performance. Therefore, it is clear that transmittance can be maintained more effectively over a longer period of time.

[0069] As is clear from the results of Examples 2 and 3, in Examples 2 and 3, where the transmittance of the chloroform solution is 80% or more, the rate of change in the luminous intensity of the light emitted from the optical lens after 3000 hours of continuous operation of the LED light source is less than -5.0% in the evaluation of long-term transmittance maintenance performance. Therefore, it is clear that transmittance can be maintained more effectively over a longer period of time.

[0070] In contrast, in Comparative Example 1, a molded article in which the transmittance of the chloroform solution is less than 65% and the reduction rate of the antioxidant is 30% or more, the evaluation of the long-term transmittance maintenance performance shows that the rate of change in the luminous intensity of the light emitted from the optical lens is -15.0% or more after 3000 hours of continuous lighting of the LED light source, indicating that the transmittance cannot be maintained over a long period of time.

[0071] As described above, the optical lens 12 of the present invention can maintain its transmittance over a long period of time. [Explanation of symbols]

[0072] 10 Optical Units 11 Housing 12 Optical Lenses 13 Optical equipment 22 Optical Lenses

Claims

1. An optical lens formed from polycarbonate resin pellets, The optical lens is an optical lens in which the transmittance of chloroform with a wavelength of 310 nm after dissolving in 5 wt% chloroform is 65% or more and 98% or less, and / or the transmittance of chloroform with a wavelength of 320 nm after dissolving in 5 wt% chloroform is 77% or more and 98% or less.

2. An optical lens according to claim 1. The optical lens is an optical lens in which the transmittance of chloroform with a wavelength of 310 nm after dissolving in 5 wt% chloroform is 80% or more and 98% or less, and / or the transmittance of chloroform with a wavelength of 320 nm after dissolving in 5 wt% chloroform is 80% or more and 98% or less.

3. A method for manufacturing an optical lens from a polycarbonate resin containing an antioxidant, A method for manufacturing an optical lens, comprising the step of injection molding the polycarbonate resin such that the content of the antioxidant in the polycarbonate resin is higher than the content of the antioxidant in the optical lens, and the difference between the two is less than 50%.

4. A method for inspecting optical lenses formed from polycarbonate resin, A method for inspecting optical lenses, which involves measuring the transmittance of chloroform with a wavelength of 310 nm or 320 nm after dissolving the optical lens in 5 wt% chloroform, thereby evaluating the transmittance maintenance performance.

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