TWI812903B - Resin lenses for head-mounted displays - Google Patents

Abstract

An object of the present invention is to provide a resin lens for a head-mounted display that can obtain clear images even with an optical system using polarized light. The lens for a head-mounted display of the present invention is characterized in that the average absolute value of the phase difference within the effective diameter is 5 nm or less, based on the excitation wavelength of 436 nm with respect to a 2.0 mass% solution obtained by dissolving it in chloroform. When measuring the fluorescence intensity at a wavelength of 530 nm, the content of the fluorescent substance calculated using the concentration-intensity conversion formula of the luciferin ethanol solution is 0.1 to 4.0×10 ^-9 mol/L.

Description

Resin lenses for head-mounted displays

The present invention relates to a resin lens for a head-mounted display.

In recent years, various electronic technologies called VR (Virtual Reality; virtual reality) and AR (Augmented Reality; augmented reality) have developed rapidly. As their image display devices, head-mounted displays (HMD: Head Mounted Display) Display) products began to spread. A head-mounted display is an image display device worn on the head. Therefore, it is required to be small, lightweight, and have less discomfort when worn.

As a method for miniaturizing a head-mounted display, the following method has been proposed: by combining a quarter-wavelength plate, a reflective polarizing plate, etc. with a lens, the polarization state of the light passing through the lens is changed and the light is reflected and transmitted. Switch between times so that the image travels one and a half round trips in one lens. (Patent Documents 1 to 2). This method is, for example, as follows: a quarter-wave plate and a reflective polarizing plate are arranged on the back of a lens whose front surface is partially reflectively coated, and the light incident as circularly polarized light from the front surface of the lens is 1/4-wavelength plated after passing through the lens. The wavelength plate converts it into linearly polarized light; this linearly polarized light is reflected by the reflective polarizing plate, and is converted again by the 1/4-wavelength plate into circularly polarized light that is opposite to the original one and is incident on the lens from the back, and the part that reaches the front surface is reflected Coating part: The light reflected by the partially reflective coating part and emitted from the back of the lens passes through the 1/4 wavelength plate and becomes linearly polarized light with a direction 90° different from the original direction. It passes through the reflective polarizing plate and is incident as an image. In eyes. In this way, a high magnification and wide field of view can be obtained in a thin optical module. [Prior technical literature] [Patent Document]

[Patent Document 1] U.S. Patent No. 6563638 [Patent Document 2] Japanese Patent Application Publication No. 2017-21321

[Problem to be solved by the invention]

However, in the above-mentioned head-mounted display, when the polarization state changes when passing through the lens, for example, after passing through the lens for the first time, part of the light will pass through the reflective polarizer, resulting in an image with a lower magnification and an image with a higher magnification. Overlapping makes it difficult to obtain a clear image. Although a clear image can be obtained by using a glass lens with less birefringence, the weight will increase, so it is not ideal. Therefore, there is an urgent need for resin lenses that are lightweight but generally prone to birefringence to produce clear images.

Therefore, an object of the present invention is to provide a resin lens for a head-mounted display that can obtain clear images even with an optical system using polarized light. [Technical means to solve problems]

The inventors of the present invention have conducted diligent research in order to solve the above problems. As a result, they found that the phase difference within the effective diameter caused by the birefringence of the resin lens affects the clarity of the image of the head-mounted display, and unexpectedly discovered that the resolution of the image in the resin lens is The content of the fluorescent substance contained affects the clarity of the image of the head-mounted display, thereby completing the present invention.

That is, the present invention is as follows. [1] A resin lens for a head-mounted display, characterized in that: the average absolute value of the phase difference within the effective diameter is 5 nm or less, based on the excitation wavelength of a 2.0 mass% solution obtained by dissolving it in chloroform. The fluorescence intensity at a wavelength of 530 nm when measured at 436 nm, and the content of the fluorescent substance calculated using the concentration-intensity conversion formula of the ethanol solution of luciferin is 0.1 to 4.0×10 ^-9 mol/L . [2] The resin lens for a head-mounted display as described in [1] has a glass transition temperature (Tg) exceeding 120°C and not exceeding 160°C. [3] The resin lens for a head-mounted display as described in [1] or [2] has an absolute value of the photoelastic coefficient of 3.0×10 ^-12 Pa ^-1 or less. [4] The resin lens for a head-mounted display according to any one of [1] to [3], which contains a methacrylic resin. [5] The resin lens for a head-mounted display according to [4], wherein the methacrylic resin contains a methacrylic resin having a structural unit (X) having a ring in the main chain structure. [6] The resin lens for a head-mounted display according to [5], wherein the structural unit (X) includes a structural unit selected from the group consisting of N-substituted maleimide monomers, glutadiimide It is at least one structural unit in the group consisting of structural units and lactone ring structural units. [7] The resin lens for a head-mounted display according to [5], wherein the structural unit (X) includes a structural unit derived from an N-substituted maleimide monomer. [8] The resin lens for a head-mounted display according to [5], wherein the structural unit (X) contains a glutadirylimide-based structural unit. [Effects of the invention]

According to the present invention, it is possible to provide a resin lens for a head-mounted display that can obtain clear images even with an optical system using polarized light.

Hereinafter, the embodiment for implementing the present invention (hereinafter referred to as “the present embodiment”) will be described in detail. However, the present invention is not limited to the following description and can be implemented with various changes within the scope of the gist.

[Resin lens for head-mounted display] The resin lens for head-mounted display according to this embodiment is characterized in that the average absolute value of the phase difference within the effective diameter is 5 nm or less, and about 2.0 obtained by dissolving it in chloroform. Mass % solution, based on the fluorescence intensity at a wavelength of 530 nm when measured at an excitation wavelength of 436 nm, the content of the fluorescent substance calculated using the concentration-intensity conversion formula of the ethanol solution of luciferin is 0.1~ 4.0×10 ^-9 mol/L.

-Phase difference within effective diameter- Regarding the resin lens for a head-mounted display in this embodiment, the average value of the absolute value of the phase difference within the effective diameter of the resin lens is 5 nm or less, preferably 4 nm or less, and more preferably 3 nm or less. By setting the average absolute value of the phase difference to 5 nm or less, double images will not appear and can be clearly recognized. Here, the effective diameter of the resin lens represents the range of the visible image when the lens is assembled into the casing of the head-mounted display. It is expressed as the diameter of a circle with the optical axis of the lens as the center, and is not true in the range of the visible image. In the case of a circle, the short diameter is regarded as the effective diameter. The phase difference within the effective diameter of the resin lens can be measured specifically by the method described in the following examples.

-Content of the fluorescent substance-In the resin lens for a head-mounted display in this embodiment, a 2.0% by mass solution obtained by dissolving the resin lens in chloroform is based on the wavelength when measured at an excitation wavelength of 436 nm. The fluorescence intensity at 530 nm and the content of the fluorescent substance calculated using the concentration-intensity conversion formula of the luciferin ethanol solution are 0.1 to 4.0×10 ^-9 mol/L, preferably 0.2 to 3.5 ×10 ^-9 mol/L, more preferably 0.3 to 3.0 × 10 ^-9 mol/L, still more preferably 0.3 to 2.5 × 10 ^-9 mol/L. By setting the content of the fluorescent substance below the above upper limit, the image will not be blurred and can be viewed clearly. Furthermore, by setting the content of the fluorescent substance to be not less than the above-mentioned lower limit, harmful low-wavelength light can be suppressed from entering the eyes excessively. The reason why the image is blurred when the fluorescence intensity is high (the content of the fluorescent substance is high) is not certain, but it is speculated that when fluorescence is generated by the light passing through the lens, the light is also directed towards the original By passing through directions other than the direction of travel of light, the image is blurred. Furthermore, it is speculated that in a head-mounted display lens that uses polarized light to be repeatedly reflected and transmitted through the lens multiple times, the optical path length when passing through the lens becomes longer, or is further greatly deviated by a reflective polarizing plate or a partially reflective coating. The blurring of the original direction of light becomes more pronounced. In addition, the content of the fluorescent substance can be specifically measured by the method described in the following Examples.

-Glass transition temperature- The glass transition temperature (Tg) of the resin lens for a head-mounted display in this embodiment is preferably more than 120°C and 160°C or less. From the viewpoint of the head-mounted display's resistance to heat generated by electronic devices or the photoelastic birefringence associated with dimensional changes, the glass transition temperature of the resin lens for the head-mounted display is preferably in excess of 120°C. From the viewpoint of dimensional stability at ambient temperature of use, the glass transition temperature (Tg) is more preferably 125°C or higher, and more preferably 130°C or higher. On the other hand, when the glass transition temperature (Tg) is below 160°C, melting processing at extremely high temperatures can be avoided, thermal decomposition of resin, etc. can be suppressed, and good products can be obtained. From the viewpoint of further obtaining the above effects, the glass transition temperature (Tg) is preferably 150°C or lower, more preferably 140°C or lower. In addition, the glass transition temperature (Tg) can be determined by measuring according to JIS-K7121. Specifically, it can be determined using the method described in the following Examples.

- Photoelastic coefficient C _R - The absolute value of the photoelastic coefficient C _R of the resin lens for the head-mounted display according to this embodiment | C _R | is preferably 3.0×10 ^-12 Pa ^-1 or less, more preferably 2.0×10 ^-12 Pa ^-1 or less, more preferably 1.5×10 ^-12 Pa ^-1 or less, further preferably 1.0×10 ^-12 Pa ^-1 or less. The photoelastic coefficient is described in various documents (for example, refer to General Chemistry, No. 39, 1998 (published by the Society Publishing Center)), and is defined by the following formulas (ia) and (ib). It can be seen that the closer the value of the photoelastic coefficient _CR is to zero, the smaller the birefringence change caused by external force. ｜C _R ｜＝｜Δn｜/σ _R・・・(ia) ｜Δn｜＝｜nx-ny｜・・・(ib) (In the formula, respectively, C _R represents the photoelastic coefficient and σ _R represents Tensile stress, |Δn| represents the absolute value of birefringence, nx represents the refractive index in the tensile direction, ny represents the refractive index in the direction perpendicular to the tensile direction) If the photoelastic coefficient C of the resin lens of this embodiment ^{If the} absolute value _{of R |} Resin lens. In addition, the photoelastic coefficient _CR was measured by chopping the resin lens into pieces and forming a laminate using a vacuum compression molding machine. Specifically, it can be determined using the method described in the following Examples.

-Transmittance- Regarding the light transmittance in the thickest part of the resin lens for a head-mounted display according to this embodiment measured using a spectrophotometer in a 10° field of view of a D65 light source, the transmittance at a wavelength of 450 nm (T450) is relative to the transmittance at a wavelength of 680 nm The ratio of transmittance (T680) in nm (T450/T680) is preferably 0.95 to 1.03, more preferably 0.97 to 1.01, further preferably 0.98 to 1.00. If the ratio (T450/T680) is within the above range, an image with good color tone can be obtained. In addition, the light transmittance can be measured specifically by the method described in the following Examples.

-Molecular weight and molecular weight distribution- The weight average molecular weight (Mw) of the resin lens for the head-mounted display in this embodiment measured by gel permeation chromatography (GPC) in terms of polymethylmethacrylate is preferably in the range of 80,000 to 170,000, and more preferably The range of 100,000 to 170,000 is preferable, the range of 100,000 to 150,000 is more preferable, and the range of 120,000 to 150,000 is more preferable. If the weight average molecular weight (Mw) is within the above range, the balance between mechanical strength and fluidity will also be excellent.

Furthermore, the weight average molecular weight (Mw), number average molecular weight (Mn), and Z average molecular weight (Mz) of the resin lens can be measured using the following equipment and conditions. ・Measuring device: Gel permeation chromatography (HLC-8320GPC) manufactured by Tosoh Co., Ltd. ・Measurement conditions: Column: Connect 1 TSKguardcolumn SuperH-H, 2 TSKgel SuperHM-M, and 1 TSKgel SuperH2500 in series. Tube string temperature: 40℃ Development solvent: tetrahydrofuran, flow rate: 0.6 mL/min, as an internal standard, 2,6-di-tert-butyl-4-methylphenol (BHT) was added at 0.1 g/L. Detector: RI (differential refraction) detector Detection sensitivity: 3.0 mV/min Sample: 0.02 g resin lens in 20 mL solution of tetrahydrofuran Injection volume: 10 μL Standard samples for calibration curve: Use the following 10 polymethyl methacrylates (manufactured by Polymer Laboratories; PMMA Calibration Kit M-M-10) with known monodisperse weight peak molecular weights and different molecular weights. Weight peak molecular weight (Mp) Standard sample 1 1,916,000 Standard sample 2 625,500 Standard sample 3 298,900 Standard sample 4 138,600 Standard sample 5 60,150 Standard sample 6 27,600 Standard sample 7 10,290 Standard sample 8 5,000 Standard sample 9 2,810 Standard sample 10 850 The RI detection intensity of the resin lens relative to the dissolution time was measured under the above conditions. Based on each calibration curve obtained by measuring the standard sample for the above calibration curve, determine the weight average molecular weight (Mw), number average molecular weight (Mn), and Z average molecular weight (Mz) of the resin lens, and use these values to determine Molecular weight distribution (Mw/Mn) and (Mz/Mw).

-Methanol-insoluble fraction- The ratio of the methanol-insoluble content of the resin lens for a head-mounted display in this embodiment to 100 mass% of the total amount of the methanol-insoluble content and the methanol-soluble content is preferably 95 mass% or more, more preferably It is 95.5 mass % or more, more preferably 96 mass % or more, still more preferably 96.5 mass % or more, especially 97 mass % or more, most preferably 97.5 mass % or more. By setting the ratio of the amount of methanol-insoluble matter to 95% by mass or more, molding problems such as silver bars during injection molding can be suppressed. In addition, the methanol-insoluble content and the methanol-soluble content refer to a chloroform solution prepared by dissolving the resin lens for a head-mounted display in chloroform, and then adding the solution dropwise to a large excess of methanol to regenerate the solution. Precipitate, classify the filtrate and filtrate, and then dry each to obtain.

Specifically, it can be obtained as follows. Dissolve 5 g of the resin lens in 100 mL of chloroform, put the solution into a dropping funnel, and add it dropwise to 1 L of methanol stirred with a stirrer over about 1 hour to reprecipitate. After the entire amount was added dropwise, the mixture was allowed to stand for 1 hour, and then, suction filtration was performed using a membrane filter (T050A090C, manufactured by Advantec Toyo Co., Ltd.) as a filter. The filtrate was vacuum-dried at 60° C. for 16 hours to prepare a methanol-insoluble fraction. Moreover, regarding the filtrate, the bath temperature of the rotary evaporator was set to 40°C, the vacuum degree was gradually reduced from the initial setting of 390 Torr, and finally set to 30 Torr. After removing the solvent, the soluble residue remaining in the eggplant-shaped flask was recovered. divided into methanol-soluble fractions. Weigh the mass of the methanol-insoluble matter and the mass of the methanol-soluble matter, and calculate the ratio (mass %) of the amount of the methanol-soluble matter to the total amount (100 mass %) of the amount of the methanol-soluble matter and the amount of the methanol-insoluble matter. %) (methanol soluble fraction).

[Resin composition] The resin lens for a head-mounted display of this embodiment preferably contains a resin composition containing a methacrylic resin.

[Methacrylic resin] The methacrylic resin contained in the resin lens for a head-mounted display of this embodiment preferably contains a structural unit (X) having a ring structure in the main chain and a structural unit derived from a methacrylate monomer. Acrylic resin. By containing a methacrylic resin, especially a methacrylic resin containing a structural unit (X) with a ring structure in the main chain and a methacrylate monomer unit, the phase difference within the effective diameter of the lens can be obtained to be sufficiently small. Also, a resin lens with a sufficiently small photoelastic coefficient.

Each structural unit is explained below.

-Structural units derived from methacrylate monomer- Examples of the structural unit derived from a methacrylic acid ester monomer include structural units derived from a monomer selected from the following methacrylic acid esters. Examples of the methacrylate include methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, and isobutyl methacrylate. , tert-butyl methacrylate, 2-ethylhexyl methacrylate, cyclopentyl methacrylate, cyclohexyl methacrylate, cyclooctyl methacrylate, tricyclodecyl methacrylate, methyl Dicyclooctyl acrylate, tricyclododecyl methacrylate, isopropyl methacrylate, phenyl methacrylate, benzyl methacrylate, 1-phenylethyl methacrylate, 2-methacrylate Phenoxyethyl ester, 3-phenylpropyl methacrylate, 2,4,6-tribromophenyl methacrylate, etc. These monomers may be used alone, or two or more types may be used in combination. As the structural unit derived from the above-mentioned methacrylate monomer, in terms of the obtained methacrylic resin having excellent transparency or weather resistance, preferred ones are those derived from methyl methacrylate and benzyl methacrylate. structural unit. The structural unit derived from the methacrylate monomer may contain only one type, or may contain two or more types.

The resin lens for a head-mounted display according to this embodiment can reduce alignment or residual stress during molding by appropriately adjusting the ratio of the structural unit (X) having a ring structure in the main chain to the structural unit derived from the methacrylate monomer. The resulting birefringence produces a resin lens for head-mounted displays whose average absolute value of phase difference within the effective diameter is 5 nm or less. Furthermore, by appropriately adjusting the above ratio, sufficient heat resistance can be imparted to the methacrylic resin. From these viewpoints, the content of the structural unit derived from the methacrylate monomer is 100% by mass, preferably 50 to 97% by mass, and more preferably 55 to 97% by mass of the methacrylic resin. , more preferably 55 to 95 mass %, still more preferably 60 to 93 mass %, particularly preferably 60 to 90 mass %. In addition, the content of the structural unit derived from the methacrylate monomer can be determined by ¹ H-NMR (Nuclear Magnetic Resonance, nuclear magnetic resonance) measurement and ¹³ C-NMR measurement. ¹ H-NMR measurement and ¹³ C-NMR measurement can be performed at a measurement temperature of 40°C using, for example, CDCl ₃ or DMSO-d ₆ as the measurement solvent.

Next, the structural unit (X) having a ring structure in the main chain will be described. The structural unit (X) having a ring structure in the main chain preferably contains a structural unit selected from the group consisting of N-substituted maleimine monomers, glutadiyl imine-based structural units, and lactone ring structures. At least one structural unit in the group of units is more preferably selected from structural units derived from N-substituted maleic imine monomers, glutadiyl imine structural units, and lactone ring structures. Composed of at least one structural unit in a group of units. The structural unit (X) having a ring structure in the main chain may be one type or a plurality of types may be combined.

-Structural unit derived from N-substituted maleimine monomer- Next, the structural unit derived from the N-substituted maleimine monomer is explained. The structural unit derived from the N-substituted maleimine monomer may be selected from the group consisting of a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2). At least one structural unit is preferably formed from both of the structural units represented by the following formula (1) and the following formula (2).

[Chemical 1] In formula (1), R ¹ represents any one of an aralkyl group having 7 to 14 carbon atoms or an aryl group having 6 to 14 carbon atoms, and R ² and R ³ each independently represent a hydrogen atom, an oxygen atom, a sulfur atom, Either an alkyl group having 1 to 12 carbon atoms or an aryl group having 6 to 14 carbon atoms. In addition, when R ² or R ³ is an aryl group, R ² or R ³ may contain a halogen atom as a substituent. Furthermore, R ¹ may be substituted by a substituent such as a halogen atom, an alkyl group having 1 to 6 carbon atoms, an alkoxy group having 1 to 6 carbon atoms, a nitro group, or a benzyl group. [Chemicalization 2] In formula (2), R ⁴ represents any one of a hydrogen atom, a cycloalkyl group having 3 to 12 carbon atoms, or an alkyl group having 1 to 12 carbon atoms, and R ⁵ and R ⁶ each independently represent a hydrogen atom, an oxygen atom, Any one of a sulfur atom, an alkyl group having 1 to 12 carbon atoms, or an aryl group having 6 to 14 carbon atoms.

Specific examples are shown below. Examples of monomers (N-arylmaleimines, N-aromatic substituted maleimides, etc.) that form the structural unit represented by formula (1) include: N- Phenylmaleimide, N-benzylmaleimide, N-(2-chlorophenyl)maleimide, N-(4-chlorophenyl)butane Enedimide, N-(4-bromophenyl)maleimide, N-(2-methylphenyl)maleimide, N-(2,6-dimethyl Phylphenyl)maleimide, N-(2-ethylphenyl)maleimide, N-(2-methoxyphenyl)maleimide, N -(2-nitrophenyl)maleimide, N-(2,4,6-trimethylphenyl)maleimide, N-(4-benzylphenyl) Maleimide, N-(2,4,6-tribromophenyl)maleimide, N-naphthylmaleimide, N-anthracenylmaleimide Imide, 3-methyl-1-phenyl-1H-pyrrole-2,5-dione, 3,4-dimethyl-1-phenyl-1H-pyrrole-2,5-dione, 1 , 3-diphenyl-1H-pyrrole-2,5-dione, 1,3,4-triphenyl-1H-pyrrole-2,5-dione, etc. Among these monomers, N-phenylmaleimide and N-benzyl are preferred in terms of the resulting methacrylic resin having excellent heat resistance and optical properties such as birefringence. Maleic imide. These monomers may be used alone, or two or more types may be used in combination.

Examples of the monomer forming the structural unit represented by the formula (2) include N-methylmaleimide, N-ethylmaleimide, and N-n-propylmaleimide. Butenedimine, N-isopropylmaleimide, N-n-butylmaleimide, N-isobutylmaleimide, N-second butylmaleimide Diamine, N-tert-butylmaleimide, N-n-pentylmaleimide, N-n-hexylmaleimide, N-n-heptylmaleimide Maleimide, N-n-octylmaleimide, N-laurylmaleimide, N-cyclopentylmaleimide, N-cyclohexylmaleimide Amine, 1-cyclohexyl-3-methyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-dimethyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-dimethyl-1H-pyrrole-2,5-dione Hexyl-3-phenyl-1H-pyrrole-2,5-dione, 1-cyclohexyl-3,4-diphenyl-1H-pyrrole-2,5-dione, etc. Among these monomers, in terms of excellent weather resistance of the methacrylic resin, N-methylmaleimide, N-ethylmaleimide, N - Isopropylmaleimide, N-cyclohexylmaleimide, and N-cyclohexylmaleimide is particularly preferred in view of the low hygroscopicity required for optical materials in recent years. Endedimide. These monomers may be used alone, or two or more types may be used in combination.

In the methacrylic resin of this embodiment, in order to express highly controlled birefringence characteristics, it is particularly preferable to combine the structural unit represented by formula (1) and the structure represented by formula (2). Units are used together. The molar ratio (X1/X2) of the content (X1) of the structural unit represented by the formula (1) to the content (X2) of the structural unit represented by the formula (2) is preferably more than 0 and less than 15, More preferably, it is more than 0 and 10 or less. When the molar ratio (X1/X2) is within this range, the resin lens of this embodiment maintains transparency without yellowing, and exhibits good heat resistance and good light without impairing environmental resistance. Elastic properties.

As the content of the structural unit derived from the N-substituted maleimine monomer, the methacrylic resin is 100% by mass, preferably in the range of 5 to 40% by mass, and more preferably 5 to 35% by mass. % range. Within this range, the methacrylic resin can obtain a more sufficient improvement effect on heat resistance, and can obtain better improvement effects on weather resistance, low water absorption, and optical properties. Furthermore, setting the content of the structural units derived from the N-substituted maleimine monomer to 40% by mass or less can effectively prevent the monomer component from remaining unreacted due to the reduction in reactivity of the monomer component during the polymerization reaction. The physical properties of the methacrylic resin decrease as the volume increases. In addition, by appropriately adjusting the content of structural units derived from N-substituted maleimide monomers within this range, birefringence caused by alignment or residual stress during molding can be reduced, and an effective diameter can be obtained. Resin lenses for head-mounted displays whose average absolute value of phase difference is 5 nm or less. Although the optimal content of structural units derived from the N-substituted maleimine monomer varies depending on the type of N-substituted maleimide, for example, when using methyl methacrylate as the methyl group When using N-phenylmaleimide and N-cyclohexylmaleimide as the N-substituted maleimide monomer, the acrylate monomer is preferably 79-83% by mass of structural units derived from methyl methacrylate, 6-8% by mass of structural units derived from N-phenylmaleimide, 6-8% by mass of structural units derived from N-cyclohexylmaleimide Adjust the unit within the range of 11 to 13% by mass.

The methacrylic resin having a structural unit derived from an N-substituted maleimide monomer constituting the resin lens for a head-mounted display according to this embodiment may also contain a methacrylic resin derived from an N-substituted maleimide monomer within a range that does not impair the object of the present invention. Structural units of other monomers that can be copolymerized with methacrylate monomers and N-substituted maleimide monomers. For example, as the above-mentioned other copolymerizable monomers, there can be exemplified: aromatic vinyl; unsaturated nitrile; acrylate having a cyclohexyl group, a benzyl group, or an alkyl group having 1 to 18 carbon atoms; a glycidyl compound; Saturated carboxylic acids, etc. Examples of the aromatic vinyl include styrene, α-methylstyrene, divinylbenzene, and the like. Examples of the unsaturated nitrile include acrylonitrile, methacrylonitrile, ethacrylonitrile, and the like. Examples of the acrylate include methyl acrylate, ethyl acrylate, propyl acrylate, isopropyl acrylate, and butyl acrylate. Examples of the glycidyl compound include glycidyl (meth)acrylate and the like. Examples of the unsaturated carboxylic acids include acrylic acid, methacrylic acid, itaconic acid, maleic acid, fumaric acid, and half-esterified products or anhydrides thereof. There may be only one type of structural unit derived from the other copolymerizable monomers, or two or more types thereof.

As the content of the structural unit derived from these other copolymerizable monomers, the methacrylic resin is 100% by mass, preferably 0 to 10% by mass, more preferably 0 to 9% by mass, and still more preferably It is 0 to 8% by mass. If the content of structural units derived from other monomers is within this range, the original effect of introducing a ring structure into the main chain will not be impaired, and the molding processability or mechanical properties of the resin can be improved, so it is preferable.

Furthermore, the content of structural units derived from N-substituted maleimine monomers and the content of structural units derived from other monomers that can be copolymerized can be measured by ¹ H-NMR and ¹³ C-NMR. And find out. ¹ H-NMR measurement and ¹³ C-NMR measurement can be performed at a measurement temperature of 40°C using, for example, CDCl ₃ or DMSO-d ₆ as the measurement solvent.

-Glutarimide structural unit- Examples of the methacrylic resin having a glutadirylimine-based structural unit in the main chain include Japanese Patent Application Laid-Open No. 2006-249202, Japanese Patent Application Laid-Open No. 2007-009182, and Japanese Patent Application Laid-Open No. 2007-009191. Methacrylic resins having glutadiylimine-based structural units described in Japanese Patent Application Publication No. 2011-186482, Japanese Republished Patent Publication No. 2012/114718, etc. can be obtained by method is formed. The glutarimide structural unit constituting the methacrylic resin of this embodiment can be formed after polymerization of the resin. Specifically, the glutadirylimine-based structural unit can be represented by the following general formula (3).

[Chemical 3] In the above general formula (3), it is preferable that R ⁷ and R ⁸ are each independently a hydrogen atom or a methyl group, R ⁹ is any one of a hydrogen atom, methyl, butyl, and cyclohexyl, and more preferably R ⁷ is Methyl group, R ⁸ is a hydrogen atom, and R ⁹ is a methyl group. The glutarimide structural unit may contain only a single type or a plurality of types.

In the methacrylic resin having a glutadirylimine-based structural unit, the content of the glutadiylimine-based structural unit is set to 100% by mass, and preferably from 3 to 70% by mass. The range is preferably 3 to 60% by mass. When the content of the glutarimide-based structural unit is within the above range, a resin with excellent molding processability, heat resistance, and optical properties can be obtained, which is preferable. In addition, by appropriately adjusting the content of the glutadirylimide structural unit within this range, the birefringence caused by the alignment or residual stress during molding can be reduced, and the average of the absolute value of the phase difference within the effective diameter can be obtained. Resin lenses for head-mounted displays with values below 5 nm. Although the optimal content of the glutadiyl imine structural unit varies depending on the types of substituents of R ⁷ to R ⁹ in the general formula (3), for example, R ⁷ and R ⁸ are hydrogen atoms, and R ⁹ is a methyl group. In the case of a base, if the content of the glutadiyl imine structural unit is in the range of 3 to 10% by mass, the birefringence caused by the alignment or residual stress during molding can be reduced, and the phase difference within the effective diameter can be obtained. The average absolute value is a resin lens for head-mounted displays below 5 nm. Furthermore, the content of the glutarimide structural unit in the methacrylic resin can be determined using the method described in the above-mentioned patent document.

The methacrylic resin having a glutarimide-based structural unit may further contain an aromatic vinyl monomer unit if necessary. The aromatic vinyl monomer is not particularly limited, and examples thereof include styrene and α-methylstyrene, with styrene being preferred.

The content of the aromatic vinyl unit in the methacrylic resin having a glutadirylimine-based structural unit is not particularly limited. Let the methacrylic resin having a glutadirylimine-based structural unit be 100 mass. %, preferably 0 to 20 mass%. If the content of the aromatic vinyl unit is within the above range, it is preferable to achieve both heat resistance and excellent photoelastic properties. For example, methyl methacrylate is used as the methacrylate monomer, styrene is used as the aromatic vinyl monomer, and the resulting methyl methacrylate-styrene copolymer is glutadiyl imidized. When obtaining a resin, 25 to 90 mass % of structural units derived from methyl methacrylate, 5 to 15 mass % of styrene-derived structural units, and 5 to 70 mass % of glutadiyl imine-based structural units are used. By adjusting within the range, the birefringence caused by the alignment or residual stress during molding can be reduced, and a resin lens for head-mounted displays with an average absolute value of the phase difference within the effective diameter below 5 nm can be obtained.

-Lactone ring structural unit- The methacrylic resin having a lactone ring structural unit in the main chain can be obtained by, for example, Japanese Patent Application Laid-Open No. 2001-151814, Japanese Patent Application Laid-Open No. 2004-168882, Japanese Patent Application Laid-Open No. 2005-146084, or Japanese Patent Application Publication No. 2005-146084. Described in Japanese Patent Laid-Open No. 2006-96960, Japanese Patent Laid-Open No. 2006-171464, Japanese Patent Laid-Open No. 2007-63541, Japanese Patent Laid-Open No. 2007-297620, Japanese Patent Laid-Open No. 2010-180305, etc. method is formed.

The lactone ring structural unit constituting the methacrylic resin of this embodiment can be formed after polymerization of the resin. As the lactone ring structural unit in this embodiment, a six-membered ring is preferred in terms of excellent stability of the ring structure. As the six-membered ring lactone ring structural unit, a structure represented by the following general formula (4) is particularly preferred.

[Chemical 4] In the above general formula (4), R ¹⁰ , R ¹¹ and R ¹² are each independently a hydrogen atom or an organic residue having 1 to 20 carbon atoms. Examples of the organic residue include: saturated aliphatic hydrocarbon groups (alkyl groups, etc.) having 1 to 20 carbon atoms, such as methyl, ethyl, and propyl groups; and unsaturated fats having 2 to 20 carbon atoms, such as vinyl groups and propenyl groups. Aromatic hydrocarbon groups (alkenyl, etc.); aromatic hydrocarbon groups with 6 to 20 carbon atoms (aryl, etc.) such as phenyl and naphthyl groups; hydrogen atoms in such saturated aliphatic hydrocarbon groups, unsaturated aliphatic hydrocarbon groups, and aromatic hydrocarbon groups One or more groups substituted by at least one selected from the group consisting of a hydroxyl group, a carboxyl group, an ether group, and an ester group.

The lactone ring structural unit can be obtained by copolymerizing an acrylic monomer having a hydroxyl group and a methacrylate monomer such as methyl methacrylate, and introducing a hydroxyl group, an ester group or a carboxyl group into the molecular chain. It is formed by dealcoholization (esterification) or dehydration condensation (hereinafter also referred to as "cyclization condensation reaction") with an ester group or carboxyl group.

Examples of the acrylic monomer having a hydroxyl group used for polymerization include 2-(hydroxymethyl)acrylic acid, 2-(hydroxyethyl)acrylic acid, and 2-(hydroxymethyl)acrylic acid alkyl ester (for example, 2-(hydroxymethyl)methyl acrylate, 2-(hydroxymethyl)ethyl acrylate, 2-(hydroxymethyl)isopropyl acrylate, 2-(hydroxymethyl)n-butyl acrylate, 2-(hydroxymethyl)acrylate tert-butyl methacrylate), 2-(hydroxyethyl)alkyl acrylate, etc., preferably 2-(hydroxymethyl)acrylic acid or 2-(hydroxymethyl)acrylic acid as a monomer having a hydroxyalkyl moiety. alkyl acrylate, particularly preferably 2-(hydroxymethyl)acrylic acid methyl ester and 2-(hydroxymethyl)acrylic acid ethyl ester.

The content of the lactone ring structural unit in the methacrylic resin having a lactone ring structural unit in the main chain is preferably 5 to 40 mass %, more preferably 5 to 35 mass % relative to 100 mass % of the methacrylic resin. %. If the content of the lactone ring structural unit is within this range, the effect of introducing a ring structure such as improved solvent resistance or improved surface hardness can be achieved while maintaining molding processability. In addition, by appropriately adjusting the content of the lactone ring structural unit within this range, the birefringence caused by the alignment or residual stress during molding can be reduced, and the average absolute value of the phase difference within the effective diameter can be obtained to be 5 Resin lenses for head-mounted displays below nm. Furthermore, the content of the lactone ring structure in the methacrylic resin can be determined using the method described in the above patent document.

The methacrylic resin having a lactone ring structural unit in the main chain may have structural units derived from other monomers copolymerizable with the methacrylate monomer and the acrylic monomer having a hydroxyl group. Examples of other copolymerizable monomers include styrene, vinyltoluene, α-methylstyrene, α-hydroxymethylstyrene, α-hydroxyethylstyrene, acrylonitrile, and methane. Acrylonitrile, methallyl alcohol, ethylene, propylene, 4-methyl-1-pentene, vinyl acetate, 2-hydroxymethyl-1-butene, methyl vinyl ketone, N-vinylpyrrole Monomers with polymerizable double bonds such as ridinone and N-vinylcarbazole. There may be only one type of these other monomers (structural units), or two or more types of them.

The content of structural units derived from other copolymerizable monomers is preferably 0 to 20 mass% based on 100 mass% of the methacrylic resin. From the viewpoint of weather resistance, it is more preferably less than 100% by mass. 10% by mass, more preferably less than 7% by mass. The methacrylic resin in this embodiment may have only one structural unit derived from the other copolymerizable monomers, or may have two or more structural units.

The methacrylic resin in this embodiment preferably has a structural unit selected from the group consisting of structural units derived from N-substituted maleimide monomers, glutadiyl imine structural units, and lactone ring structural units. At least one structural unit among the group, among which, in particular, in terms of easily and highly controlling optical properties such as photoelastic coefficient without blending other thermoplastic resins, it is particularly preferred to have one derived from N-substituted maleimide. The structural unit of a monomer. Furthermore, in particular, from the viewpoint of obtaining a high-strength resin lens, it is particularly preferred to have a glutadirylimide-based structural unit.

[Production method of methacrylic resin] Hereinafter, the manufacturing method of the methacrylic resin of this embodiment is demonstrated.

-Production method of methacrylic resin containing structural units derived from N-substituted maleimine monomer- As a method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimine monomer in the main chain (hereinafter, sometimes referred to as "maleimine copolymer"), Any of the polymerization methods, including block polymerization, solution polymerization, suspension polymerization, precipitation polymerization, and emulsion polymerization, can be used to reduce the amount of residual monomers or impurities contained in the resin lens. Suspension polymerization, block polymerization, and solution polymerization are preferred, and solution polymerization is more preferred.

In the manufacturing method in this embodiment, as a polymerization form, any one of a batch polymerization method, a semi-batch polymerization method, and a continuous polymerization method can be used, for example. In this embodiment, from the viewpoint of reducing the amount of maleimide remaining at the end of polymerization and reducing the fluorescence intensity (reduce the content of the fluorescent substance), it is preferable to use a so-called semi-batch process. The polymerization method is a method in which a part of the monomer is put into a reactor before polymerization is started and a polymerization initiator is added, thereby starting polymerization and then supplying the remaining part of the monomer.

Regarding the methacrylic resin having a structural unit derived from an N-substituted maleimide monomer, the obtained resin lens is controlled so as to express a specific fluorescence intensity (the content of the fluorescent substance is: Specific scope) method, for example, at least one of the following steps can be performed: (1) using N-substituted maleimine monomer with controlled specific impurity content as a raw material; (2) Use a polymerization method that reduces the amount of unreacted N-substituted maleimide remaining after polymerization; (3) Use a devolatization method that reduces shear; among them, the preferred combination is (1) and (3) ), or choose a manufacturing method that combines the three.

(1) Control of impurities in N-substituted maleimides As one of the impurities in N-substituted maleimide that imparts fluorescence to methacrylic resins, N-substituted maleimide may be produced by reacting with a primary amine. 2-Amino-N-substituted succinimine. Examples of 2-amino-N-substituted succinimide include 2-cyclohexylamino-N-cyclohexylsuccinimide, 2-anilino-N-phenylsuccinimide, and the like. . According to the research conducted by the inventors, it is clearly known that 2-amino-N-substituted succinimide not only has fluorescence itself, but also, although the detailed modification mechanism is not clear, when it is heated to 300°C or above, , or when supplied to a devolatilization device with shear, a thermally modified substance with fluorescent luminescence will be produced. That is, in order to control the fluorescence intensity of the methacrylic resin and the obtained resin lens, it is preferable to reduce the amount of 2-amino-N-substituted succinidine contained in the N-substituted maleimide. amine, and in the production of methacrylic resin, a devolatilization device without a rotating part is used to perform devolatization at 300°C or below.

As a method of controlling impurities in N-substituted maleimide, there can be exemplified a method of providing a pretreatment step, and the pretreatment step is to perform water washing of N-substituted maleimide (water washing step). ) and/or dehydration (dehydration step). The above pretreatment step may be only water washing, or may be a combination of water washing and dehydration. In addition, water washing and dehydration may be performed once each, or may be performed a plurality of times. In the above pretreatment step, a concentration adjustment step for adjusting the concentration of the N-substituted maleimide solution obtained in the dehydration step may also be provided.

In this embodiment, for example, the 2-amino-N-substituted succinimide in the N-substituted maleic imine is removed by using a water washing step as described below, and in the subsequent dehydration step By removing the water, an N-substituted maleimide solution suitable for preparing a methacrylic resin with controlled fluorescence intensity and good color tone can be obtained. In the water washing step, for example, the following method can be used: dissolve N-substituted maleimide in a water-insoluble organic solvent, separate it into an organic layer and an aqueous layer, and use an acidic aqueous solution for the organic layer, One or more liquids among water and alkaline aqueous solution are mixed and washed by a batch method, a continuous method, or both methods, and then the organic layer and the aqueous layer are separated.

When the amount of N-substituted maleimide in the organic layer is set to 100% by mass, the amount of 2-amino-N-substituted maleimide in the organic layer after the water washing step is preferably It is 5 mass ppm or less, more preferably 0.1 mass ppm or more and 1 mass ppm or less. If the amount of 2-amino-N-substituted succinimide in the organic layer is within this range, the concentration of the fluorescent substance in the methacrylic resin and the obtained resin lens can be controlled as described above. Within the range, it is possible to obtain a resin lens for a head-mounted display that can obtain clear images, so it is preferable. In addition, it is also better in terms of cost during cleaning. When the dehydration step is not provided, the organic layer containing N-substituted maleimide obtained in the water washing step can also be used as an N-substituted maleimide solution in the polymerization step. Furthermore, the amount of 2-amino-N-substituted succinimide in the organic layer can be measured by gas chromatography, liquid chromatography, etc., using isopropyl benzoate as an internal standard material. , specifically, it can be measured using the method described in the following examples.

The water-insoluble organic solvent used must be a solvent that dissolves N-substituted maleimine and 2-amino-N-substituted succinimide, separates from water, and has an azeotropic point with water. , there are no special restrictions. Specifically, for example, aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as n-hexane and cyclohexane; and halogenated hydrocarbons such as chloroform and dichloroethane can be used. The water used can be sewage, pure water, or clean water. In addition, the acidity of the acidic aqueous solution and the alkaline aqueous solution is not particularly limited.

The concentration of N-substituted maleimide in the organic layer before the water washing step is preferably 0.5 mass% or more and 30 mass% or less, more preferably 10 mass% or more and 25 mass% or less, and still more preferably 20 mass% % or more and less than 25% by mass. The temperature when the organic layer and the aqueous layer are mixed and washed only needs to be 40°C or higher, preferably 40°C or higher and 80°C or lower, more preferably 50°C or higher and 60°C or lower. When the mass of the organic layer is 100 mass %, the mass ratio of the aqueous layer to the organic layer is preferably 5 mass % or more and 300 mass % or less, more preferably 10 mass % or more and 200 mass % or more, and still more preferably It is 30 mass % or more and 100 mass % or less. If the concentration of N-substituted maleimide in the organic layer, the liquid temperature during washing, and the mass ratio of the aqueous layer are within these ranges, then the ratio of N-substituted maleimide to water will be The reaction does not proceed easily, and 2-amino-N-substituted succinimide is easily extracted to the aqueous layer side, so it is preferable.

In the case of batch cleaning, the reaction tank used may be made of stainless steel or glass-lined, or a reaction tank other than these may be used. In addition, there is no particular restriction on the shape of the stirring blade. As specific stirring blades, for example, 3 swept blades, 4 paddle blades, 4 inclined paddle blades, 6 turbine blades, and anchor blades can be used. In addition, TWINSTIR or FULLZONE manufactured by KOBELCO ECO-SOLUTIONS can be used. . The stirring time is preferably from 10 minutes to 120 minutes, more preferably from 30 minutes to 60 minutes. In addition, the stirring speed is appropriately selected so that the mixed liquid becomes turbulent and does not emulsify. If the stirring time and stirring speed are within this range, the stirring efficiency and the efficiency of extracting 2-amino-N-substituted succinimine into the aqueous layer will be improved, which can further reduce the amount of N-substituted maleimine. Among the amines, 2-amino-N-substituted succinimine is preferred.

In the case of continuous cleaning, an empty tower, a packed tower, or a plate tower can be used, a static mixer such as a static mixer, or a rotary mixer such as a dynamic mixer can be used. The contact time between the organic layer and the aqueous layer is preferably set to not less than 1 second and not more than 60 minutes, more preferably not less than 30 seconds and not more than 10 minutes. If the contact time is within this range, the reaction between N-substituted maleimine and water will not proceed easily, and 2-amino-N-substituted maleimine will be easily extracted to the water layer side, so Better.

In the dehydration step, the organic layer is supplied to the reaction tank and heated under reduced pressure to remove moisture. The pressure and temperature are not particularly limited as long as the solvent used and water form an azeotropic composition. When the mass of the organic layer is set to 100 mass %, the moisture content in the organic layer after the dehydration step is preferably 100 mass ppm or less. If the moisture content after the dehydration step is within this range, it is possible to suppress the deterioration of the color tone due to water during the polymerization of the methacrylic resin, and to reduce the amount of solvent that is distilled away together with the water, so it is cost-effective. , is also better. The organic layer containing N-substituted maleimide obtained in the dehydration step can be used as an N-substituted maleimide solution in the polymerization step, and can also be adjusted in the concentration adjustment step. A solution of N-substituted maleimide at a constant concentration was used in the polymerization step.

In the concentration adjustment step, for example, the above-mentioned water-insoluble organic solvent may also be used to dilute the organic layer of the above-mentioned N-substituted maleimide obtained in the dehydration step and the like. The non-water-soluble organic solvent used in the concentration adjustment step is preferably the same as the non-water-soluble organic solvent used in the water washing step.

The N-substituted maleimide solution obtained in the above pretreatment step is preferably a solution (organic layer) of the above-mentioned water-insoluble organic solvent. Regarding the N-substituted maleimine solution obtained in the above pretreatment step, the 2-amino-N-substituted succinimide contained in the N-substituted maleimine solution The mass ratio is preferably 5 mass ppm or less, more preferably 0.1 mass ppm or more relative to 100 mass % of N-substituted maleimide contained in the N-substituted maleimide solution. 1 mass ppm or less. The water content contained in the N-substituted maleimide solution obtained in the above pretreatment step is preferably 200 mass ppm or less relative to 100 mass% of the N-substituted maleimide solution. More preferably, it is 100 to 200 mass ppm. The mass ratio of the N-substituted maleimide contained in the N-substituted maleimide solution obtained in the above pretreatment step relative to the N-substituted maleimide solution is 100 Mass%, preferably 5 to 30 mass%, more preferably 5 to 25 mass%. When the solution is within this range, the N-substituted maleimide is less likely to precipitate and can be transferred as a uniform solution, which is preferable.

When using a plurality of N-substituted maleimide solutions in the polymerization step, it is preferable that a mixture of a plurality of N-substituted maleimide solutions satisfies the above 2-amino-N- The mass ratio of the substituted succinimine, the above-mentioned moisture content, and/or the mass ratio of the above-mentioned N-substituted maleimide, more preferably, each N-substituted maleimine solution satisfies the above 2 -The mass ratio of amino-N-substituted succinimide, the above-mentioned moisture content, and/or the mass ratio of the above-mentioned N-substituted maleicimide. By using the water washing step and dehydration step of N-substituted maleimide as mentioned above, the fluorescent 2-amino-N-substituted maleimide can be reduced and the phosphorus-causing methylamine can be removed. It is preferable to remove the moisture that causes the color tone of the acrylic resin to deteriorate, and to obtain a methacrylic resin and a combination of the resin that also has a good color tone in a lens with a long optical path length. In the polymerization step, the methacrylate monomer, any other monomer, polymerization initiator, polymerization solvent, and chain may also be mixed into the N-substituted maleimide solution obtained in the above pretreatment step. Transfer agent, etc., is used for polymerization after preparing a monomer mixture.

(2) Reduction of unreacted N-substituted maleimide at the end of polymerization The present inventors discovered that if unreacted N-substituted maleimide exists at the end of the polymerization of methacrylic resin, although the detailed mechanism is not clear, sometimes it will occur in the heated devolatilization device. Etc. generates a low molecular weight and fluorescent reaction by-product containing N-substituted maleimide as its structural unit.

In order to control the content of the fluorescent substance in the methacrylic resin and the obtained resin lens within the above range, it is preferable to reduce the remaining amount after the polymerization to 100% by mass of the polymerization solution at the end of the polymerization. The total mass of the reacted N-substituted maleimide is 1000 mass ppm or less, more preferably 10 mass ppm or more and 500 mass ppm or less. Furthermore, when N-arylmaleimides such as N-phenylmaleimide are used as N-substituted maleimides, unreacted N- will remain after the polymerization is completed. The total mass of arylmaleimines is preferably 500 mass ppm or less, more preferably 10 mass ppm or more, and 500 mass ppm or less, based on 100 mass % of the polymerization solution at the end of polymerization, and still more preferably 10 mass ppm. ppm and above 50 mass ppm and below. Within these ranges, it is preferable because the content of the fluorescent substance in the methacrylic resin and the obtained resin lens can be suppressed within the above range. In addition, in order to reduce the amount of unreacted N-substituted maleimide to less than 10 ppm by mass, it is necessary to increase the polymerization temperature or increase the amount of polymerization initiator. Therefore, thermal modification of maleimide is required. It is undesirable because the amount of reactive substances or active free radicals will increase, which will cause the color tone of the methacrylic resin to deteriorate.

An example of a method for controlling the amount of unreacted N-substituted maleimide after completion of polymerization to be within the above range is a semi-batch polymerization method. In the semi-batch polymerization method, in the polymerization step, 30 minutes after starting to add the polymerization initiator, all monomers supplied to the polymerization (for example, methacrylate, N-substituted maleimide, and any other monomers) is set to 100 mass%, and it is preferable to additionally add 5 to 35 mass% of methacrylate monomer. In other words, it is preferable to put 65 to 95 mass % of the total mass of 100 mass % of all monomers supplied for polymerization into the reactor before adding the polymerization initiator, and to add the polymerization initiator 30 minutes after the start of the addition. The remainder of the methacrylate monomer is added in an amount of 5 to 35% by mass. The total mass of all monomers supplied for polymerization is 100% by mass, and the amount of additional methacrylate monomer is more preferably 10 to 30% by mass. If the amount of the additionally added methacrylate monomer is within the above range, the unreacted N-substituted maleimine will react with the additionally added methacrylate monomer, and the unreacted N-substituted maleimide after the polymerization is completed can be It is preferable to control the amount of N-substituted maleimide within the above range.

The timing of starting the additional addition of the monomer, the speed of the additional addition, etc. can be appropriately selected based on the polymerization conversion rate. In addition, in addition to the methacrylate monomer, N-substituted maleimide may also be additionally added within a range that does not hinder the effect of the present invention or reduce the amount of unreacted N-substituted maleimide. Imine monomer or monomer mixture of other monomers. By using the semi-batch polymerization method as described above, the amount of unreacted N-substituted maleimide monomer in the second half of the polymerization can be reduced, so that the fluorescent substance can be generated in the devolatilization step. At a minimum, it is preferable to obtain a methacrylic resin and a composition of the resin that also have a good color tone in a lens with a long optical path length.

Hereinafter, as an example of a method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimine monomer, a case where it is produced by radical polymerization in a semi-batch manner using a solution polymerization method will be described in detail. to explain.

In the semi-batch polymerization method, 30 minutes after starting to add the polymerization initiator, all the monomers (methacrylate, N-substituted maleimide, and any other monomers) supplied for the polymerization are The total mass is set to 100 mass%, and it is preferable to additionally add 5 to 35 mass% of methacrylate monomer. In other words, it is preferable to put 65 to 95 mass % of the total mass of 100 mass % of all monomers supplied for polymerization into the reactor before the start of polymerization, and to add the methyl group 30 minutes after the start of adding the polymerization initiator. The remainder of the acrylate monomer is 5 to 35% by mass. The total mass of all monomers supplied for polymerization is 100% by mass, and the amount of additional methacrylate monomer is more preferably 10 to 30% by mass.

The timing of starting the additional addition of the monomer, the speed of the additional addition, etc. can be appropriately selected based on the polymerization conversion rate. In addition, in addition to the methacrylate monomer, N-substituted maleimine monomers may also be additionally added within a range that does not hinder the effects of the present invention or the improvement of the conversion rate of the N-substituted maleimine monomer. Elendiimide monomer or monomer mixture of other monomers.

By using the semi-batch polymerization method as described above, the conversion rate of N-substituted maleimide monomers in the second half of the polymerization can be increased, the content of fluorescent substances can be reduced, and the optical path length can be longer. The lens has excellent light transmittance, can easily control the molecular weight distribution of the obtained polymer, and can obtain a resin having fluidity suitable for injection molding and a composition of the resin, so it is preferable.

The polymerization solvent used is not limited as long as it can increase the solubility of the maleimide copolymer obtained by polymerization and maintain the viscosity of the reaction liquid appropriately for the purpose of preventing gelation, etc. Special restrictions. Specific polymerization solvents include, for example, aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and cumene; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone, and cyclohexanone. ; Dimethylformamide, 2-methylpyrrolidone and other polar solvents. These can be used individually or in combination of 2 or more types. In addition, alcohols such as methanol, ethanol, and isopropyl alcohol may be used together as the polymerization solvent within a range that does not inhibit the dissolution of the polymer product during polymerization.

The amount of solvent during polymerization is not particularly limited as long as it is an amount that allows polymerization to proceed, does not cause precipitation of copolymers or used monomers during production, and can be easily removed. For example, when mixing the monomers to be prepared, When the total amount is 100% by mass, it is preferably 10 to 200% by mass. More preferably, it is 25-150 mass %, Still more preferably, it is 40-100 mass %, Even more preferably, it is 50-100 mass %. In this embodiment, it is also preferable to use the following method: when the total amount of the monomers to be prepared is 100 mass %, the amount of solvent during polymerization is within the range of 100 mass % or less, while polymerizing Polymerization is carried out while appropriately changing the solvent concentration. More specifically, the following method can be exemplified: 40 to 60 mass % is blended in the initial stage of polymerization, the remaining 60 to 40 mass % is blended in the middle of polymerization, and the total amount of monomers blended is finally set to 100 mass %. , so that the solvent amount is within the range of 100 mass% or less. By using this method, the polymerization conversion rate can be increased, the molecular weight distribution can be controlled, the injection moldability is excellent, the content of fluorescent substances can be reduced, and a lens with a long optical path length can be produced with good color tone. Resins and resin compositions are preferred.

In solution polymerization, it is important to reduce the dissolved oxygen concentration in the polymerization solution as much as possible. For example, the dissolved oxygen concentration is preferably below 10 ppm. The dissolved oxygen concentration can be measured using, for example, a dissolved oxygen meter DO Meter B-505 (manufactured by Iijima Electronics Co., Ltd.). As a method to reduce the concentration of dissolved oxygen, the following methods can be appropriately selected: a method of introducing an inert gas into the polymerization solution; before polymerization, the inert gas is used to pressurize the container containing the polymerization solution to about 0.2 MPa and then the pressure is released, and the process is repeated The method of this operation; the method of passing inert gas into the container containing the polymerization solution.

The polymerization temperature is not particularly limited as long as the polymerization proceeds, but it is preferably 70 to 180°C, more preferably 80 to 160°C, further preferably 90 to 150°C, still more preferably 100 to 150°C. ℃. From the viewpoint of productivity, the temperature is preferably 70°C or higher. In order to suppress side reactions during polymerization and obtain a polymer of required molecular weight or quality, the temperature is preferably 180°C or lower.

In addition, the polymerization time is not particularly limited as long as the required degree of polymerization can be obtained at the required conversion rate. However, from the viewpoint of productivity, etc., it is preferably 2 to 15 hours, and more preferably 3 hours. ~12 hours, more preferably 4-10 hours.

As the polymerization initiator, any initiator commonly used in free radical polymerization can be used, for example, cumene hydroperoxide, dicumyl peroxide, di-tert-butyl peroxide, peroxide, etc. Lauryl oxide, benzoyl peroxide, tert-butyl peroxyisopropyl carbonate, tert-amyl peroxy-2-ethylhexanoate, tert-amyl peroxyisononanoate, 1,1-di (Tertiary butyl peroxide) cyclohexane and other organic peroxides; 2,2'-azobisisobutyronitrile, 1,1'-azobis(cyclohexanecarbonitrile), 2,2'-azobis(cyclohexanecarbonitrile), Azo compounds such as azobis(2,4-dimethylvaleronitrile), dimethyl-2,2'-azobisisobutyrate, etc. These may be used individually, or 2 or more types may be used together. When the total amount of monomers used for polymerization is 100 mass %, the addition amount of the polymerization initiator can be 0.01 to 1 mass %, and is preferably in the range of 0.05 to 0.5 mass %. The method of adding the polymerization initiator is not particularly limited as long as it is added variably according to the concentration of the monomer remaining in the polymerization solution rather than at a fixed addition rate. It can be added continuously or intermittently. added. When the polymerization initiator is added intermittently, the amount added per unit time is not considered with respect to the time when the polymerization initiator is not added.

In this embodiment, it is preferable to appropriately select the polymerization starting point so that the ratio of the total amount of free radicals generated by the polymerization initiator to the total amount of unreacted monomers remaining in the reaction system is always a fixed value or less. The type and amount of the agent, as well as the polymerization temperature, etc. By using these methods, it is also possible to suppress the formation of oligomers or low molecular weight bodies in the later stages of polymerization, or to suppress overheating during polymerization, thereby achieving polymerization stability.

During the polymerization reaction, a chain transfer agent may also be added as needed to perform polymerization. As the chain transfer agent, a general chain transfer agent used in radical polymerization can be used, for example, n-butyl mercaptan, n-octyl mercaptan, n-decyl mercaptan, n-dodecyl mercaptan, and thioglycolic acid 2 - Thiol compounds such as ethylhexyl ester; halogen compounds such as carbon tetrachloride, methylene chloride, and tribromomethane; α-methylstyrene dimer, α-terpinene, dipentene, terpinene, etc. Unsaturated hydrocarbon compounds, etc. These may be used individually, or 2 or more types may be used together. As long as the polymerization reaction is in progress, the chain transfer agents can be added at any stage without particular limitation. When the total amount of monomers used for polymerization is 100% by mass, the amount of chain transfer agent added can be 0.01 to 1% by mass, preferably 0.05 to 0.5% by mass.

An example of a method for recovering a polymer from a polymerization liquid obtained by solution polymerization is to separate the polymerization solvent or unreacted monomers through a step called a devolatilization step to recover a polymerization product. Among them, the devolatilization step refers to the step of removing volatile components such as polymerization solvent, residual monomers, reaction by-products, etc. under heating and reduced pressure conditions. In this embodiment, it is preferable to control the content of the unreacted N-substituted maleimine monomer contained in the polymerization solution containing the methacrylic resin supplied to the devolatization step to a certain concentration. the following. Details are described in the above "(2) Reduction of unreacted N-substituted maleimide at the end of polymerization". However, in addition to the above method, for example, in order to increase the conversion rate of the monomer, the following method can also be used Etc.: The method of prolonging the polymerization time as much as possible, or changing the addition rate of the polymerization initiator according to the concentration of unreacted monomers in the polymerization solution to carry out the polymerization; the method of carrying out the polymerization while appropriately changing the solvent concentration during the polymerization; additional Method of adding other monomers with higher reactivity with the N-substituted maleimide monomer remaining in the second half of the polymerization; adding α-terpinene, etc. and N-substituted maleimide at the end of the polymerization Methods for compounds with higher reactivity of imines.

-Residual amount of N-substituted maleic imine monomer- As a method of determining the remaining amount of the N-substituted maleimide monomer remaining in the polymerization solution containing the methacrylic resin, it can be determined by, for example, the following method: taking and weighing a portion of the polymerization solution. , the sample was dissolved in chloroform to prepare a 5% by mass solution, n-decane was added as an internal standard material, and the N-substituted cis remaining in the sample was measured using gas chromatography (GC-2010 manufactured by Shimadzu Corporation). Concentration of butenediamide monomer. As more specific measurement conditions, those described in the following examples can be used.

(3) Devolatilization method that reduces shear As a device used in the above-mentioned devolatization step, it is preferable to use a devolatilization device whose main components are a heat exchanger and a decompression container and which does not have a rotating part as its structure. By not providing a rotating part, shearing during devolatization can be reduced, and a resin with even lower fluorescence luminescence can be obtained. Specifically, a devolatilization device including a devolatization tank and a discharge device such as a gear pump can be used. The devolatization tank is a decompression vessel with a decompression unit attached to it. The decompression vessel is equipped with a heat exchanger at its upper part. And it has a size that can be devolatized, and discharge devices such as gear pumps are used to discharge the devolatized polymer. The above-mentioned devolatilization device supplies the polymerization solution to a heated heat exchanger arranged on the upper part of the decompression vessel, such as a multi-tube heat exchanger, a plate-fin heat exchanger, a flat plate with a flat plate flow path and a heater. After preheating with a heat exchanger, etc., it is supplied to a devolatization tank under heating and reduced pressure, and the polymerization solvent, unreacted raw material mixture, polymerization by-products, etc. are separated and removed from the polymer. By using a devolatilization device without a rotating part as described above, low molecular weight fluorescent reaction by-products derived from unreacted N-substituted maleimide can be suppressed, and methacrylic acid can be converted into It is preferable to control the fluorescence intensity (content of the fluorescent substance) in the resin and the obtained resin lens within a specific range. In addition, it is preferable because it can obtain a methacrylic resin with a good color tone.

Examples of devices having the above-mentioned rotating part include thin film evaporators such as WIPRENE and EXEVA manufactured by KOBELCO ECO-SOLUTIONS, Kontro and Diagonal-blade Kontro manufactured by Hitachi Ltd.; extruders with vents, etc.

In the devolatization step in this embodiment, the shear rate applied to the polymerization solution is preferably 20 s ^-1 or less, more preferably 10 s ^-1 or less, and still more preferably 0.1 s. ^-1 or above and 10 s for ^-1 or below. By setting the shear rate to 0.1 s ^-1 or more, the flow of the molten resin does not become too slow, and the deterioration of the color tone due to an increase in residence time can be suppressed. In addition, by setting it to 20 s ^-1 or less, the generation of reaction by-products having fluorescence luminescence due to shearing can be suppressed. Among them, for example, the shear rate γ in the extruder is calculated using the following formula. γ=(π×D×N)/H (where D represents the screw diameter (m), N represents the screw rotation speed per second, and H represents the screw groove depth (m)) Also, in the case of a flat-plate flow path When , the shear rate γ is calculated using the following formula. γ=(6×Q)/(w×h ² ) (where Q represents the volume flow rate through the flat plate flow path (m ³ /s), w represents the width of the flat plate flow path (m), and h represents the flat plate distance between (m))

In this embodiment, as the heat exchanger arranged at the upper part of the pressure reducing vessel, it is preferable to use a flat plate heat exchanger having a flat plate type flow path and a heater. More preferably, it is a flat plate heat exchanger having a flat plate type flow path and a heater having a laminated structure having a plurality of slit-like flow paths with rectangular cross-sections in the same plane.

The polymerization solution supplied to the devolatilization device is sent from the center of the heat exchanger to the slit-shaped flow path and heated. The heated polymerization solution is supplied from the slit-shaped flow path into a decompression container under reduced pressure integrated with the heat exchanger, and is flash evaporated. This kind of devolatilization method is sometimes also called flash devolatization. In the present invention, it is also referred to as flash devolatization below.

The following method can also be used: 2 or more of the above-mentioned devolatilization devices are installed in series, and the devolatilization is performed in more than 2 stages.

The temperature range for heating using the heat exchanger attached to the devolatilization device can be set to 100°C or more and 300°C or less, preferably a temperature between the glass transition temperature (Tg) of the methacrylic resin + 100°C to Tg + 160°C , more preferably the temperature is Tg＋110℃～Tg＋150℃. The temperature range of the heated and insulated devolatization tank can be set to 100°C or more and 300°C or less, preferably Tg+100°C to Tg+160°C, more preferably Tg+110°C to Tg+150°C. If the temperatures of the heat exchanger and devolatilization tank are within this range, the thermal modification of the remaining 2-amino-N-substituted succinimide can be inhibited, and the generation of fluorescent substances can be inhibited, so it is relatively good. In addition, it is preferable to effectively prevent the residual volatile matter from increasing and improve the thermal stability and product quality of the methacrylic resin obtained.

The degree of vacuum in the devolatization tank can be set in the range of 5 to 300 Torr, and preferably in the range of 10 to 200 Torr. If the degree of vacuum is 300 Torr or less, unreacted monomers or a mixture of unreacted monomers and polymerization solvents can be efficiently separated and removed, and the thermal stability or quality of the obtained thermoplastic copolymer will not be reduced. If the vacuum degree is 5 Torr or above, it is easier to implement industrially.

The average residence time in the devolatization tank is 5 to 60 minutes, preferably 5 to 45 minutes. If the average residence time is within this range, it is preferable because devolatilization can be performed efficiently and coloring or decomposition caused by thermal modification of the polymer can be suppressed.

The polymer recovered from the devolatilization step is processed into granules using a step called a granulation step. In the granulation step, at least one selected from the group consisting of a gear pump, a single-screw extruder, and a twin-screw extruder having a porous die as an accessory device is used to move the molten resin into a pelletizing device. Shape extrusion, using cold cutting method, aerial thermal cutting method, underwater strand cutting method, and underwater cutting method to process into granular shape. From the viewpoint of suppressing the formation of fluorescent reaction by-products due to shearing, it is preferable not to use an extruder and to select a conveying device with a low shearing rate.

In this embodiment, in order to obtain a highly controlled resin composition, it is preferable to adopt a granulation method. This granulation method prevents the resin composition in a molten state at high temperatures from coming into contact with air as much as possible, allowing it to be rapidly cooled and solidified. . In this case, it is better to lower the temperature of the molten resin as much as possible, minimize the residence time from the exit of the porous die to the cooling water surface, and perform granulation under conditions where the temperature of the cooling water is as high as possible. . For example, the molten resin temperature is preferably 220 to 280°C, more preferably 230 to 270°C, and the residence time from the porous die outlet to the cooling water surface is preferably within 5 seconds, more preferably within 3 seconds. As a cooling The temperature of the water is preferably in the range of 30 to 80°C, more preferably in the range of 40 to 60°C.

By performing the method within the range of the molten resin temperature and the cooling water temperature, it is possible to obtain a methacrylic resin and a composition thereof that are less colored and contain a low moisture content, which is preferable.

Regarding the content of residual monomers in the methacrylic resin after the devolatization step, from the viewpoint of thermal stability or product quality, the lower the better. Specifically, the content of the methacrylate monomer is preferably 3000 mass ppm or less, more preferably 2000 mass ppm or less. The content of the N-substituted maleimine monomer is preferably 200 mass ppm or less, and more preferably 100 mass ppm or less in terms of total amount. Furthermore, the content of the residual polymerization solvent is preferably 500 mass ppm or less, more preferably 300 mass ppm or less.

-Production method of methacrylic resin containing glutadirylimide structural unit- Examples of a method for producing a methacrylic resin having a glutadirylimine-based structural unit in the main chain include block polymerization, solution polymerization, suspension polymerization, precipitation polymerization, and emulsion polymerization. , suspension polymerization, block polymerization, and solution polymerization are preferred, and solution polymerization is further preferred. In the manufacturing method in this embodiment, as a polymerization form, any one of a batch polymerization method, a semi-batch polymerization method, and a continuous polymerization method can be used, for example. In the manufacturing method in this embodiment, it is preferable to polymerize the monomer by radical polymerization.

Examples of methacrylic resins having a glutadirylimine-based structural unit in the main chain include Japanese Patent Application Laid-Open No. 2006-249202, Japanese Patent Application Laid-Open No. 2007-009182, Japanese Patent Application Laid-Open No. 2007-009191, and The methacrylic resin having a glutarimide-based structural unit described in Japanese Patent Application Laid-Open No. 2011-186482, International Publication No. 2012/114718, etc. can be formed by the method described in the publication. Hereinafter, as an example of a method for producing a methacrylic resin having a glutadirylimide-based structural unit, a case where the methacrylic resin is produced by a batch-type radical polymerization using a solution polymerization method will be specifically described.

First, a (meth)acrylate polymer is produced by polymerizing (meth)acrylate esters such as methyl methacrylate. When an aromatic vinyl unit is contained in a methacrylic resin having a glutadirylimide structural unit, (meth)acrylate and aromatic vinyl (for example, styrene) are copolymerized to produce (meth)acrylate. base) acrylate-aromatic vinyl copolymer.

Examples of the solvent used for polymerization include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. These solvents may be used alone, or two or more types may be used in combination. The amount of solvent during polymerization is not particularly limited as long as it is an amount that allows polymerization to proceed, does not cause precipitation of copolymers or used monomers during production, and can be easily removed. For example, when mixing the monomers to be prepared, When the total amount is 100% by mass, it is preferably 10 to 200% by mass. More preferably, it is 25-200 mass %, still more preferably 50-200 mass %, still more preferably 50-150 mass %.

The polymerization temperature is not particularly limited as long as the polymerization proceeds, but it is preferably 50 to 200°C, more preferably 80 to 200°C. It is more preferably 90 to 150°C, still more preferably 100 to 140°C, still more preferably 100 to 130°C. From the viewpoint of productivity, the temperature is preferably 70°C or higher. In order to suppress side reactions during polymerization and obtain a polymer of required molecular weight or quality, the temperature is preferably 180°C or lower. The polymerization time is not particularly limited as long as it satisfies the target conversion rate. However, from the viewpoint of productivity, etc., it is preferably 0.5 to 15 hours, more preferably 2 to 12 hours, and still more preferably 4 to 10 hours. .

During the polymerization reaction, a polymerization initiator or chain transfer agent may also be added as needed to perform polymerization.

The polymerization initiator is not particularly limited, and for example, the polymerization initiator disclosed in the above method for preparing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer can be used. These polymerization initiators may be used alone, or two or more types may be used in combination. The polymerization initiators can be added at any stage as long as the polymerization reaction is in progress. The amount of the polymerization initiator to be added is not particularly limited as long as it is appropriately set according to the combination of monomers, reaction conditions, etc., and when the total amount of monomers used for polymerization is 100% by mass, it can be 0.01 to 1% by mass, preferably 0.05 to 0.5% by mass.

As the chain transfer agent, a chain transfer agent used in general free radical polymerization can be used. For example, the above method for preparing a methacrylic resin having a structural unit derived from an N-substituted maleimine monomer can be used. chain transfer agent, etc. These can be used individually or in combination of 2 or more types. As long as the polymerization reaction is in progress, the chain transfer agents can be added at any stage without particular limitation. The amount of the chain transfer agent added is not particularly limited as long as it is within a range that can obtain the desired degree of polymerization under the polymerization conditions used. However, it is preferable that the total amount of monomers used for polymerization be 100. In the case of mass %, it can be 0.01 to 1 mass %, preferably 0.05 to 0.5 mass %.

Preferable methods for adding the polymerization initiator and the chain transfer agent in the polymerization step can be, for example, as described in the above-described method for producing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer. method. The concentration of dissolved oxygen in the polymerization solution may be, for example, the value disclosed in the method for preparing the methacrylic resin having a structural unit derived from an N-substituted maleimide monomer.

Next, an imidization reaction (imidization step) is performed by reacting an imidization agent with the (meth)acrylate polymer or the methacrylate-aromatic vinyl copolymer. Thereby, a methacrylic resin having a glutarimide-based structural unit can be produced.

The imidizing agent is not particularly limited as long as it can produce the glutarimide-based structural unit represented by the general formula (3). As the imidizing agent, specifically, ammonia or a primary amine can be used. Examples of the above-mentioned primary amine include primary amines containing aliphatic hydrocarbon groups such as methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, tert-butylamine, n-hexylamine, etc.; cyclohexylamine, etc. Primary amines containing alicyclic hydrocarbon groups, etc. Among the above-described imidizing agents, in terms of cost and physical properties, ammonia, methylamine, and cyclohexylamine are preferred, and methylamine is particularly preferred.

In the imidization step, by adjusting the addition ratio of the above-mentioned imidization agent, the glutadiyl imine system in the obtained methacrylic resin having a glutadiyl imine structural unit can be adjusted. Content of structural units.

The method used to implement the above-mentioned imidization reaction is not particularly limited, and previously known methods can be used. For example, the imidization reaction can be performed by using an extruder or a batch reaction tank.

The extruder is not particularly limited, and for example, a single-screw extruder, a twin-screw extruder, a multi-screw extruder, etc. can be used. Among them, it is preferable to use a twin-screw extruder. The twin-screw extruder can be used to promote the mixing of raw polymer and imidization agent. Examples of the twin-screw extruder include a non-meshing type co-rotating type, an intermeshing type co-rotating type, a non-meshing type different direction rotation type, an intermeshing type different direction rotation type, and the like. The extruders illustrated above can be used alone, or a plurality of them can be connected in series. In addition, it is particularly preferable to install an exhaust port on the extruder used that can reduce the pressure to below atmospheric pressure, so that reaction by-products such as imidizing agents, methanol, or monomers can be removed.

When producing a methacrylic resin having a glutadiyl imide structural unit, in addition to the above-mentioned imidization step, an esterification step of treating the carboxyl group of the resin with an esterification agent such as dimethyl carbonate may also be included. . At this time, catalysts such as trimethylamine, triethylamine, and tributylamine may also be used together for treatment. The esterification step can be performed in the same manner as the above-mentioned imidization step, for example, by using an extruder or a batch reaction tank. In addition, for the purpose of removing excess esterification agent, by-products such as methanol, or monomers, it is preferable to install an exhaust port that can reduce the pressure to below atmospheric pressure in the device used.

The methacrylic resin that has undergone the imidization step and, if necessary, the esterification step is melted and extruded in a linear form from an extruder equipped with a porous die, using cold cutting, aerial thermal cutting, or an underwater line. Material cutting method, underwater cutting method, etc. are processed into granular form. In addition, in order to reduce the number of foreign matter in the resin, it is also preferable to use the following method: dissolve the methacrylic resin in an organic solvent such as toluene, methyl ethyl ketone, and methylene chloride, and dissolve the obtained methacrylic resin. The solution was filtered, after which the organic solvent was evaporated.

From the viewpoint of reducing the fluorescence intensity (the content of the fluorescent substance), it is preferable to imidize the polymerization solution after the polymerization is completed in a batch reaction tank without using a biaxial shear force. Extruder. The imidization reaction is preferably carried out at 130 to 250°C, more preferably at 150 to 230°C, still more preferably at 170 to 190°C. Moreover, the reaction time is preferably 10 minutes to 5 hours, more preferably 30 minutes to 2 hours. After the imidization step, from the viewpoint of reducing the fluorescence intensity, it is preferable to undergo an esterification step if necessary, by using the above-mentioned methyl group having a structural unit derived from an N-substituted maleimine monomer. (3) The shear-reducing devolatilization method described in the preparation method of acrylic resin is followed by devolatization and then granulation.

-Production method of methacrylic resin containing lactone ring structural unit- As a method for producing a methacrylic resin having a lactone ring structural unit in the main chain, a method is used to form a lactone ring structure through a cyclization reaction after polymerization. However, in terms of promoting the cyclization reaction, it is preferable to use Solution polymerization using solvents polymerizes monomers by free radical polymerization. In the manufacturing method in this embodiment, as a polymerization form, any one of a batch polymerization method, a semi-batch polymerization method, and a continuous polymerization method can be used, for example. The methacrylic resin having a lactone ring structural unit in the main chain can be obtained by, for example, Japanese Patent Application Laid-Open No. 2001-151814, Japanese Patent Application Laid-Open No. 2004-168882, Japanese Patent Application Laid-Open No. 2005-146084, or Japanese Patent Application Publication No. 2005-146084. Described in Japanese Patent Laid-Open No. 2006-96960, Japanese Patent Laid-Open No. 2006-171464, Japanese Patent Laid-Open No. 2007-63541, Japanese Patent Laid-Open No. 2007-297620, Japanese Patent Laid-Open No. 2010-180305, etc. method is formed.

Hereinafter, as an example of a method for producing a methacrylic resin having a lactone ring structural unit, a case where it is produced by radical polymerization in a batchwise manner using a solution polymerization method will be specifically described. As a method for producing a methacrylic resin having a lactone ring structural unit, a method of forming a lactone ring structure by a cyclization reaction after polymerization is used. However, in terms of promoting the cyclization reaction, a method using a solvent is preferred. Solution polymerization.

Examples of the solvent used for polymerization include aromatic hydrocarbons such as toluene, xylene, and ethylbenzene; and ketones such as methyl ethyl ketone and methyl isobutyl ketone. These solvents may be used alone, or two or more types may be used in combination.

The amount of solvent during polymerization is not particularly limited as long as the polymerization proceeds and gelation is suppressed. For example, it is preferable when the total amount of the monomers to be prepared is 100% by mass. It is 50-200 mass %, and it is more preferable that it is 100-200 mass %.

In order to fully suppress the gelation of the polymerization liquid and promote the cyclization reaction after polymerization, it is preferable to conduct polymerization so that the concentration of the generated polymer in the reaction mixture obtained after polymerization becomes 50 mass % or less. Furthermore, it is preferable to appropriately add the polymerization solvent to the reaction mixture and control the concentration to be 50 mass % or less.

The method of appropriately adding the polymerization solvent to the reaction mixture is not particularly limited. For example, the polymerization solvent may be added continuously or intermittently. The polymerization solvent added may be a single solvent or a mixture of two or more solvents. The polymerization temperature is not particularly limited as long as the polymerization proceeds, but from the viewpoint of productivity, it is preferably 50 to 200°C, and more preferably 80 to 180°C. The polymerization time is not particularly limited as long as it satisfies the target conversion rate. However, from the viewpoint of productivity, etc., it is preferably 0.5 to 10 hours, and more preferably 1 to 8 hours.

During the polymerization reaction, a polymerization initiator or chain transfer agent may also be added as needed to perform polymerization. The polymerization initiator is not particularly limited, and for example, the polymerization initiator disclosed in the above method for preparing a methacrylic resin having a structural unit derived from an N-substituted maleimide monomer can be used. These polymerization initiators may be used alone, or two or more types may be used in combination. The polymerization initiators can be added at any stage as long as the polymerization reaction is in progress. The amount of the polymerization initiator to be added is not particularly limited as long as it is appropriately set according to the combination of monomers, reaction conditions, etc., and when the total amount of monomers used for polymerization is 100% by mass, it can be 0.05～1% by mass.

As the chain transfer agent, a chain transfer agent used in general free radical polymerization can be used. For example, the above method for preparing a methacrylic resin having a structural unit derived from an N-substituted maleimine monomer can be used. chain transfer agent, etc. These can be used individually or in combination of 2 or more types. As long as the polymerization reaction is in progress, the chain transfer agents can be added at any stage without particular limitation. The amount of the chain transfer agent added is not particularly limited as long as it is within a range that can obtain the desired degree of polymerization under the polymerization conditions used. However, it is preferable that the total amount of monomers used for polymerization be 100. In the case of mass %, it can be set to 0.05 to 1 mass %.

Preferable methods for adding the polymerization initiator and chain transfer agent in the polymerization step can be, for example, those described in the above-mentioned preparation method of the methacrylic resin having structural units derived from N-substituted maleimide monomers. method.

The concentration of dissolved oxygen in the polymerization solution may be, for example, the value disclosed in the method for preparing the methacrylic resin having a structural unit derived from an N-substituted maleimide monomer.

The methacrylic resin having a lactone ring structural unit in this embodiment can be obtained by performing a cyclization reaction after completion of the above-mentioned polymerization reaction. Therefore, it is preferable not to remove the polymerization solvent from the polymerization reaction liquid, but to supply it to the lactone cyclization reaction in a state containing the solvent. The copolymer obtained by polymerization is heated, and a cyclization condensation reaction occurs between the hydroxyl and ester groups present in the molecular chain of the copolymer, forming a lactone ring structure. During heat treatment to form a lactone ring structure, a vacuum device for removing alcohol that may be a by-product of cyclization and condensation, a reaction device with a devolatization device, an extruder with a devolatization device, etc. can also be used.

When forming a lactone ring structure, in order to promote the cyclization condensation reaction, a cyclization condensation catalyst may also be used for heat treatment if necessary. Specific examples of the cyclization condensation catalyst include: methyl phosphite, ethyl phosphite, phenyl phosphite, dimethyl phosphite, diethyl phosphite, diphenyl phosphite, and phosphorous acid. Trimethyl phosphate, triethyl phosphite and other monoalkyl, dialkyl or trialkyl phosphites; methyl phosphate, ethyl phosphate, 2-ethylhexyl phosphate, octyl phosphate, isodecyl phosphate Ester, lauryl phosphate, stearyl phosphate, isostearyl phosphate, dimethyl phosphate, diethyl phosphate, di(2-ethylhexyl) phosphate, diisodecyl phosphate, dilauryl phosphate, phosphoric acid Distearyl phosphate, diisostearyl phosphate, trimethyl phosphate, triethyl phosphate, triisodecyl phosphate, trilauryl phosphate, tristearyl phosphate, triisostearyl phosphate and other phosphate monoalkyl Ester, dialkyl ester or trialkyl ester; organic zinc compounds such as zinc acetate, zinc propionate, octyl zinc, etc. These can be used individually or in combination of 2 or more types.

The usage amount of the cyclization condensation catalyst is not particularly limited. For example, it is preferably 0.01 to 3 mass %, and more preferably 0.05 to 1 mass % based on 100 mass % of the methacrylic resin. If the catalyst is used in an amount of 0.01% by mass or more, it is effective in increasing the reaction rate of the cyclization condensation reaction. If the catalyst is used in an amount of 3% by mass or less, it is effective in preventing the obtained polymer from coloring or polymerization. The material is cross-linked and difficult to melt and form.

The timing of adding the cyclization condensation catalyst is not particularly limited. For example, it may be added at the initial stage of the cyclization condensation reaction, in the middle of the reaction, or at both of these stages. When the cyclization condensation reaction is carried out in the presence of a solvent, devolatilization can also be carried out at the same time.

There is no particular limitation on the device used when performing the cyclization condensation reaction and the devolatilization step at the same time. Preferably, it is a devolatilization device including a heat exchanger and a devolatization tank or an extruder with a vent, and , preferably a devolatilization device and an extruder configured in series, and more preferably a twin-screw extruder with vent holes. As the twin-screw extruder with a vent to be used, a vent-equipped extruder having a plurality of vents is preferred.

When an extruder with a vent is used, the reaction treatment temperature is preferably 150 to 350°C, more preferably 200 to 300°C. If the reaction treatment temperature is less than 150°C, the cyclization condensation reaction may become insufficient and residual volatile matter may increase. On the contrary, if the reaction treatment temperature exceeds 350° C., coloring or decomposition of the obtained polymer may occur. When using an extruder with a vent, the degree of vacuum is preferably 10 to 500 Torr, more preferably 10 to 300 Torr. If the vacuum degree exceeds 500 Torr, volatile components may easily remain. On the contrary, if the vacuum degree is less than 10 Torr, it may be difficult to implement industrially.

When performing the above-mentioned cyclization condensation reaction, for the purpose of deactivating the remaining cyclization condensation catalyst, it is also preferred to add alkaline earth metal and/or amphoteric metal salts of organic acids during granulation. As the alkaline earth metal and/or amphoteric metal salt of the organic acid, for example, calcium acetoacetate, calcium stearate, zinc acetate, zinc octoate, zinc 2-ethylhexanoate, etc. can be used.

After the cyclization condensation reaction step, the methacrylic resin is melted and extruded in a linear form from an extruder equipped with a porous die, using cold cutting, aerial thermal cutting, underwater strand cutting, and underwater cutting. The cutting method is processed into granular shape. Furthermore, lactonization to form the above-mentioned lactone ring structural unit can be performed after producing the resin and before producing the resin composition (as described below), or can be performed with the resin and other components other than the resin during the production of the resin composition. The ingredients are melted and kneaded at the same time.

From the viewpoint of reducing the fluorescence intensity (the content of the fluorescent substance), it is preferable to lactone cyclize the polymerization solution after the polymerization in a batch reaction tank without using a biaxial shear force. Extruder. After the lactone cyclization step, from the viewpoint of reducing the fluorescence intensity, it is preferable to prepare the methacrylic resin having a structural unit derived from an N-substituted maleimide monomer as described above. The devolatilization method of reducing shear described in (3) is followed by devolatization and then granulation.

[Additive] The resin composition constituting the resin lens for a head-mounted display according to this embodiment may contain various additives within the above-mentioned range that does not significantly impair the effects of the present invention. The additives are not particularly limited, and examples thereof include antioxidants, light stabilizers such as hindered amine light stabilizers, ultraviolet absorbers, release agents, other thermoplastic resins, paraffinic processing oils, and naphthenic processing oils. Treatment oil, aromatic processing oil, paraffin, organic polysiloxane, mineral oil and other softeners, plasticizers, flame retardants, antistatic agents, organic fibers, iron oxide and other pigments and other inorganic fillers, glass Reinforcing agents and colorants such as fibers, carbon fibers, and metal whiskers; organophosphorus compounds such as phosphites, phosphonite diesters, and phosphates, other additives, or mixtures thereof, etc.

-Antioxidants- The resin composition constituting the resin lens for a head-mounted display according to this embodiment preferably contains an antioxidant that suppresses deterioration or coloration during molding or use. Examples of the antioxidant include hindered phenol antioxidants, phosphorus antioxidants, sulfur antioxidants, etc., but are not limited thereto. These antioxidants may be used alone or in combination of two or more types. Furthermore, from the viewpoint of improving thermal stability or suppressing molding defects, it is preferable to use a plurality of thermal stabilizers in combination. For example, it is preferable to use at least one selected from a phosphorus-based antioxidant and a sulfur-based antioxidant and a hindered phenol. Used together with antioxidants.

Examples of hindered phenol antioxidants include pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], thiodiethylenebis[3-( 3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 3 ,3',3'',5,5',5''-hexa-tert-butyl-a,a',a''-(mesitylene-2,4,6-triyl)tri-p-cresol , 4,6-bis(octylthiomethyl)o-cresol, 4,6-bis(dodecylthiomethyl)o-cresol, ethylbis(oxyethylene)bis[3- (5-tert-butyl-4-hydroxym-tolyl)propionate], hexamethylenebis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], 1,3,5-tris(3,5-di-tert-butyl-4-hydroxybenzyl)-1,3,5-tris-2,4,6(1H,3H,5H)-trione, 1,3,5-tris[(4-tert-butyl-3-hydroxy-2,6-xylene)methyl]-1,3,5-tris-2,4,6(1H,3H, 5H)-triketone, 2,6-di-tert-butyl-4-(4,6-bis(octylthio)-1,3,5-tri-triketone-2-ylamine)phenol, acrylic acid 2- [1-(2-Hydroxy-3,5-di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl ester, 2-tert-butyl acrylate-4-methyl- 6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl ester, etc., but are not limited thereto. Particularly preferred are pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-tert-butyl-4- Hydroxyphenyl)propionate, 2-[1-(2-hydroxy-3,5-di-tertiary pentylphenyl)ethyl]-4,6-di-tertiary pentylphenyl acrylate.

In addition, as the hindered phenolic antioxidant as the above-mentioned antioxidant, a commercially available phenolic antioxidant can be used. Examples of such a commercially available phenolic antioxidant include: Irganox 1010 (Irganox 1010: pentaerythritol tetrakis[3-( 3,5-di-tert-butyl-4-hydroxyphenyl)propionate], manufactured by BASF), Irganox 1076 (Irganox 1076: octadecyl-3-(3,5-di-tert-butyl- 4-Hydroxyphenyl)propionate, manufactured by BASF), Irganox 1330 (Irganox 1330: 3,3',3'',5,5',5''-hexatertiary butyl-a,a', a''-(mesitylene-2,4,6-trisyl)tris-p-cresol, manufactured by BASF), Irganox 3114 (Irganox 3114: 1,3,5-tris(3,5-di-tert-butyl) -4-Hydroxybenzyl)-1,3,5-tris-2,4,6(1H,3H,5H)-trione, manufactured by BASF Corporation), Irganox 3125 (manufactured by BASF Corporation), Adekastab AO-60 (Pentaerythritol tetrakis[3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], manufactured by ADEKA), Adekastab AO-80 (3,9-bis{2-[3-( 3-tert-butyl-4-hydroxy-5-methylphenyl)propionyloxy]-1,1-dimethylethyl}-2,4,8,10-tetraxaspiro[5.5] Undecane, manufactured by ADEKA Corporation), Sumilizer BHT (manufactured by Sumitomo Chemical), Cyanox 1790 (manufactured by Cytec), Sumilizer GA-80 (manufactured by Sumitomo Chemical), Sumilizer GS (Sumilizer GS: acrylic acid 2-[1-(2-hydroxy -3,5-Di-tert-pentylphenyl)ethyl]-4,6-di-tert-pentylphenyl ester, manufactured by Sumitomo Chemical), Sumilizer GM (Sumilizer GM: 2-tert-butyl-4 acrylate -Methyl-6-(2-hydroxy-3-tert-butyl-5-methylbenzyl)phenyl ester, manufactured by Sumitomo Chemical), vitamin E (manufactured by Eisai), etc., but are not limited thereto. Among these commercially available phenolic antioxidants, Irganox 1010, Adekastab AO-60, Adekastab AO-80, Irganox 1076, Sumilizer GS, etc. are preferred from the viewpoint of imparting thermal stability effects to the resin. Only one type of these may be used alone, or two or more types may be used in combination.

Examples of the phosphorus-based antioxidant include tris(2,4-di-tert-butylphenyl)phosphite and bis(2,4-bis(1,1-)phosphite). Dimethylethyl)-6-methylphenyl)ethyl ester, tetrakis(2,4-di-tert-butylphenyl)(1,1-biphenyl)-4,4'-diylbisphosphine Acid diester, bis (2,4-di-tert-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol diphosphite, bis (2,4-dicumylphenyl)pentaerythritol-diphosphite, tetrakis(2,4-tert-butylphenyl)(1,1-biphenyl)-4,4'-diylbis Phosphite diester, di-tert-butyl-m-tolyl-phosphonite diester, 4-[3-[(2,4,8,10-tetratert-butyldibenzo[d,f] [1,3,2]dioxaphosphepane)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol and the like, but are not limited thereto.

Furthermore, commercially available phosphorus-based antioxidants can also be used as the phosphorus-based antioxidants. Examples of such commercially available phosphorus-based antioxidants include: Irgafos 168 (Irgafos 168: tris(2,4-di-phosphorous acid) tert-butylphenyl) ester, manufactured by BASF), Irgafos 12 (Irgafos 12: tris[2-[[2,4,8,10-tetra-tertiary butyldibenzo[d,f][1, 3,2]dioxaphosphepan-6-yl]oxy]ethyl]amine, manufactured by BASF, Irgafos 38 (Irgafos 38: phosphite bis(2,4-bis(1,1-bis) Methylethyl)-6-methylphenyl)ethyl ester, manufactured by BASF), Adekastab 329K (ADK STAB-229K, manufactured by ADEKA), Adekastab PEP-36 (ADK STAB PEP-36, manufactured by ADEKA), Adekastab PEP- 36A (ADK STAB PEP-36A, manufactured by ADEKA), Adekastab PEP-8 (ADK STAB PEP-8, manufactured by ADEKA), Adekastab HP-10 (ADK STAB HP-10, manufactured by ADEKA), Adekastab 2112 (ADK STAB 2112, manufactured by ADEKA Company), Adekastab 1178 (ADKA STAB 1178, made by ADEKA), Adekastab 1500 (ADK STAB 1500, made by ADEKA), Sandstab P-EPQ (made by Clariant), Weston 618 (made by GE), Weston 619G (made by GE), Ultranox 626 (manufactured by GE), Sumilizer GP (Sumilizer GP: 4-[3-[(2,4,8,10-tetra-tert-butyldibenzo[d,f][1,3,2]dioxy Phosphocycloheptene)-6-yloxy]propyl]-2-methyl-6-tert-butylphenol, manufactured by Sumitomo Chemical), HCA (9,10-dihydro-9-oxa- 10-phosphaphenanthrene-10-oxide, manufactured by Samko Co., Ltd.), etc., but are not limited thereto. Among these commercially available phosphorus-based antioxidants, Irgafos 168, Adekastab PEP-36, and Adekastab PEP-36A are preferred from the viewpoint of the thermal stability-imparting effect in the resin and the effect of combined use with various antioxidants. , Adekastab HP-10, Adekastab 1178, especially Adekastab PEP-36A, Adekastab PEP-36. Only one type of these phosphorus-based antioxidants may be used alone, or two or more types may be used in combination.

In addition, as the sulfur-based antioxidant as the above-mentioned antioxidant, for example, 2,4-bis(dodecylthiomethyl)-6-methylphenol (Irganox 1726, manufactured by BASF), 2, 4-bis(octylthiomethyl)-6-methylphenol (Irganox 1520L, manufactured by BASF), 2,2-bis{[3-(dodecylthio)-1-oxopropoxy [Basic]methyl}propane-1,3-diylbis[3-dodecylthio]propionate] (Adekastab AO-412S, manufactured by ADEKA), 2,2-bis{[3-(十Dialkylthio)-1-oxopropoxy]methyl}propane-1,3-diylbis[3-dodecylthio]propionate] (KEMINOX PLS, Chemipro Kasei Co., Ltd. (manufactured by ADEKA), bis(tridecyl)3,3'-thiodipropionate (AO-503, manufactured by ADEKA), etc., but are not limited thereto. Among these commercially available sulfur-based antioxidants, Adekastab AO-412S and KEMINOX PLS are preferred from the viewpoint of the thermal stability-imparting effect in the resin, the effect of combined use with various antioxidants, and the operability. . Only one type of these sulfur-based antioxidants may be used alone, or two or more types may be used in combination.

The content of the antioxidant only needs to be an amount that can achieve the effect of improving thermal stability. If the content is excessive, problems such as bleeding during processing may occur. Therefore, compared to 100% by mass of methacrylic resin, it is less It is preferably 5 mass % or less, more preferably 3 mass % or less, still more preferably 1 mass % or less, still more preferably 0.8 mass % or less, still more preferably 0.01 to 0.8 mass %, particularly preferably 0.01 to 0.5 mass %. %.

The timing of adding the antioxidant is not particularly limited, but examples include: adding it to the monomer solution before polymerization and then starting polymerization; adding and mixing it to the polymer solution after polymerization and then supplying it to the devolatization step ; A method of adding and mixing the polymer in a molten state after devolatization and then granulating it; a method of adding and mixing the devolatilized and granulated particles when they are melted and extruded again, etc. Among them, from the viewpoint of preventing thermal deterioration or coloration in the devolatization step, it is preferable to add the antioxidant after adding and mixing it to the polymer solution after polymerization and before the devolatilization step, and then supply it to the devolatilization step. volatilization step.

-Hindered amine light stabilizer- The resin composition constituting the resin lens for a head-mounted display according to this embodiment may contain a hindered amine light stabilizer. The hindered amine light stabilizer is not particularly limited, but a compound containing three or more ring structures is preferred. Among them, the ring structure is preferably at least one selected from the group consisting of aromatic rings, aliphatic rings, aromatic heterocyclic rings, and non-aromatic heterocyclic rings, when one compound has two or more ring structures. At this time, they can be the same as each other or different. Specific examples of the hindered amine light stabilizer include bis(1,2,2,6,6-pentamethyl-4-piperidyl)[[3,5-bis(1,1 -Dimethylethyl)-4-hydroxyphenyl]methyl]butylmalonate, bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate Mixture with methyl 1,2,2,6,6-pentamethyl-4-piperidyl sebacate, bis(2,2,6,6-tetramethyl-4-piperidyl)decane Diacid ester, N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-N,N'-dimethylacylhexamethylenediamine, dibutylamine- 1,3,5-Tris-N,N'-bis(2,2,6,6-tetramethyl-4-piperidinyl)-1,6-hexamethylenediamine and N-(2 ,Condensation polymer of 2,6,6-tetramethyl-4-piperidinyl)butylamine, poly[{6-(1,1,3,3-tetramethylbutyl)amino-1,3, 5-Tris-2,4-diyl}{(2,2,6,6-tetramethyl-4-piperidinyl)imino}hexamethylene{(2,2,6,6- Tetramethyl-4-piperidyl)imino}], tetrakis(1,2,2,6,6-pentamethyl-4-piperidyl)butane-1,2,3,4-tetrakis Carboxylic acid ester, tetrakis(2,2,6,6-tetramethyl-4-piperidyl)butane-1,2,3,4-tetracarboxylic acid ester, 1,2,2,6,6- Pentamethyl-4-piperidinol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxasspiro[5.5]undecane-3,9-diethanol Reactants, 2,2,6,6-tetramethyl-4-piperidinol and β,β,β',β'-tetramethyl-2,4,8,10-tetraxaspiro[5.5] Reactant of undecane-3,9-diethanol, bis(1-undecyloxy-2,2,6,6-tetramethylpiperidin-4-yl) carbonate, 1,2,2 , 6,6-pentamethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, etc., but are not limited thereto. Among them, preferred is bis(1,2,2,6,6-pentamethyl-4-piperidinyl)[[3,5-bis(1,1-dimethylethyl) containing three or more ring structures (Hydroxyphenyl)-4-hydroxyphenyl]methyl]butylmalonate, dibutylamine-1,3,5-tris-N,N'-bis(2,2,6,6-tetramethyl -Condensation polymer of -4-piperidinyl)-1,6-hexamethylenediamine and N-(2,2,6,6-tetramethyl-4-piperidinyl)butylamine, poly[{6 -(1,1,3,3-tetramethylbutyl)amino-1,3,5-tri-2,4-diyl}{(2,2,6,6-tetramethyl-4 -Piperidinyl)imino}hexamethylene{(2,2,6,6-tetramethyl-4-piperidinyl)imino}], 1,2,2,6,6-penta Reaction of methyl-4-piperidinol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxasspiro[5.5]undecane-3,9-diethanol substance, 2,2,6,6-tetramethyl-4-piperidinol and β,β,β',β'-tetramethyl-2,4,8,10-tetraoxasspiro[5.5] A reactant of alkane-3,9-diethanol. The content of the hindered amine light stabilizer only needs to be an amount that can achieve the effect of improving light stability. When the content is excessive, there is a risk of problems such as bleeding during processing. Therefore, compared to methacrylic resin 100 % by mass, preferably 5 mass% or less, more preferably 3 mass% or less, still more preferably 1 mass% or less, still more preferably 0.8 mass% or less, still more preferably 0.01 to 0.8 mass%, particularly preferably 0.01～0.5% by mass.

--UV absorber-- The resin composition constituting the resin lens for a head-mounted display according to this embodiment may contain an ultraviolet absorber. The ultraviolet absorber is not particularly limited, but is preferably an ultraviolet absorber that has a maximum absorption wavelength of 280 to 380 nm. Examples include benzotriazole compounds, benzotriazole compounds, and diphenyl. Ketone compounds, oxybenzophenone compounds, benzoate compounds, phenol compounds, oxazole compounds, cyanoacrylate compounds, benzotrione compounds, etc. Examples of benzotriazole-based compounds include: 2,2'-methylenebis[4-(1,1,3,3-tetramethylbutyl)-6-(2H-benzotriazole- 2-yl)phenol], 2-(3,5-di-tert-butyl-2-hydroxyphenyl)-5-chlorobenzotriazole, 2-(2H-benzotriazole-2-yl)p Cresol, 2-(2H-benzotriazol-2-yl)-4,6-bis(1-methyl-1-phenylethyl)phenol, 2-benzotriazol-2-yl-4 ,6-di-tert-butylphenol, 2-[5-chloro(2H)-benzotriazol-2-yl]-4-methyl-6-tert-butylphenol, 2-(2H-benzotriazol-2-yl) Triazol-2-yl)-4,6-di-tert-butylphenol, 2-(2H-benzotriazol-2-yl)-4-(1,1,3,3-tetramethylbutyl )phenol, 2-(2H-benzotriazol-2-yl)-4-methyl-6-(3,4,5,6-tetrahydrophthalyliminomethyl)phenol, toluene The reaction product of 3-(3-(2H-benzotriazol-2-yl)-5-tert-butyl-4-hydroxyphenyl)propionate/polyethylene glycol 300, 2-(2H- Benzotriazole-2-yl)-6-(linear and side chain dodecyl)-4-methylphenol, 2-(5-methyl-2-hydroxyphenyl)benzotriazole, 2 -[2-Hydroxy-3,5-bis(α,α-dimethylbenzyl)phenyl]-2H-benzotriazole, 3-(2H-benzotriazol-2-yl)-5- (1,1-Dimethylethyl)-4-hydroxy-C7-9 side chain and linear alkyl esters. Among them, benzotriazole compounds with a molecular weight of 400 or more are preferred. For example, in the case of commercially available products, Kemisorb (registered trademark) 2792 (manufactured by Chemipro Kasei) and Adekastab (registered trademark) can be cited. LA31 (manufactured by ADEKA Co., Ltd.), Tinuvin (registered trademark) 234 (manufactured by BASF Corporation), etc. Examples of the benzotrixacin-based compound include 2-mono(hydroxyphenyl)-1,3,5-trixacin compounds and 2,4-bis(hydroxyphenyl)-1,3,5-tritrixacin compounds. , 2,4,6-tris(hydroxyphenyl)-1,3,5-tris𠯤 compounds, specifically, 2,4-diphenyl-6-(2-hydroxy-4-methyl Oxyphenyl)-1,3,5-triphosphate, 2,4-diphenyl-6-(2-hydroxy-4-ethoxyphenyl)-1,3,5-triphosphate, 2, 4-diphenyl-(2-hydroxy-4-propoxyphenyl)-1,3,5-trihydroxyphenyl, 2,4-diphenyl-(2-hydroxy-4-butoxyphenyl) -1,3,5-triphosphate, 2,4-diphenyl-6-(2-hydroxy-4-butoxyphenyl)-1,3,5-triphosphate, 2,4-diphenyl -6-(2-hydroxy-4-hexyloxyphenyl)-1,3,5-trihydroxyphenyl, 2,4-diphenyl-6-(2-hydroxy-4-octyloxyphenyl)- 1,3,5-trisulfenyl, 2,4-diphenyl-6-(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-trisphenyl, 2,4-diphenyl Base-6-(2-hydroxy-4-benzyloxyphenyl)-1,3,5-trihydroxyphenyl, 2,4-diphenyl-6-(2-hydroxy-4-butoxyethoxy) )-1,3,5-tributoxyphenyl, 2,4-bis(2-hydroxy-4-butoxyphenyl)-6-(2,4-dibutoxyphenyl)-1,3-5 -Tris, 2,4,6-tris(2-hydroxy-4-methoxyphenyl)-1,3,5-tris, 2,4,6-tris(2-hydroxy-4-ethoxy 2,4,6-tris(2-hydroxyphenyl)-1,3,5-tris(2-hydroxyphenyl)-1,3,5-tris, 2,4,6- Tris(2-hydroxy-4-butoxyphenyl)-1,3,5-tris(2-hydroxy-4-butoxyphenyl)-1,3,5 -Tris, 2,4,6-tris(2-hydroxy-4-hexyloxyphenyl)-1,3,5-tris, 2,4,6-tris(2-hydroxy-4-octyloxy) 2,4,6-tris(2-hydroxyphenyl)-1,3,5-tris(2-hydroxyphenyl)-1,3,5-tris(2,4,6-tris(2-hydroxy-4-dodecyloxyphenyl)-1,3,5-tris(2), 2,4, 6-Tris(2-hydroxy-4-benzyloxyphenyl)-1,3,5-tris(2-hydroxy-4-ethoxyethoxyphenyl)-1 ,3,5-Tris(2-hydroxy-4-butoxyethoxyphenyl)-1,3,5-tris(2,4,6-tris(2- Hydroxy-4-propoxyethoxyphenyl)-1,3,5-tris(2-hydroxy-4-methoxycarbonylpropoxyphenyl)-1,3 ,5-Tris(2-hydroxy-4-ethoxycarbonylethoxyphenyl)-1,3,5-tris(2,4,6-tris(2- Hydroxy-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)phenyl)-1,3,5-trihydroxy, 2,4,6-tri (2-Hydroxy-3-methyl-4-methoxyphenyl)-1,3,5-tris(2-hydroxy-3-methyl-4-ethoxy) Phenyl)-1,3,5-tris(tris), 2,4,6-tris(2-hydroxy-3-methyl-4-propoxyphenyl)-1,3,5-tris(2), 2, 4,6-tris(2-hydroxy-3-methyl-4-butoxyphenyl)-1,3,5-tris, 2,4,6-tris(2-hydroxy-3-methyl- 4-butoxyphenyl)-1,3,5-tris(2-hydroxyphenyl)-1,3,5-tris(2-hydroxy-3-methyl-4-hexyloxyphenyl)-1,3,5- Tris, 2,4,6-tris(2-hydroxy-3-methyl-4-octyloxyphenyl)-1,3,5-tris, 2,4,6-tris(2-hydroxy- 3-Methyl-4-dodecyloxyphenyl)-1,3,5-tris(2-hydroxy-3-methyl-4-benzyloxyphenyl) -1,3,5-Tris, 2,4,6-Tris(2-hydroxy-3-methyl-4-ethoxyethoxyphenyl)-1,3,5-Tris, 2,4 ,6-tris(2-hydroxy-3-methyl-4-butoxyethoxyphenyl)-1,3,5-tris, 2,4,6-tris(2-hydroxy-3-methyl) -4-propoxyethoxyphenyl)-1,3,5-tris-tris(2-hydroxy-3-methyl-4-methoxycarbonylpropoxyphenyl) -1,3,5-Tris, 2,4,6-Tris(2-hydroxy-3-methyl-4-ethoxycarbonylethoxyphenyl)-1,3,5-Tris, 2 ,4,6-tris(2-hydroxy-3-methyl-4-(1-(2-ethoxyhexyloxy)-1-oxopropan-2-yloxy)phenyl)-1, 3,5-三𠯤etc. As the benzotrisulfate-based compound, commercially available products can be used. For example, Kemisorb 102 (manufactured by Chemipro Kasei Co., Ltd.), LA-F70 (manufactured by ADEKA Co., Ltd.), LA-46 (manufactured by ADEKA Co., Ltd.), Tinuvin 405 ( BASF Corporation), Tinuvin 460 (BASF Corporation), Tinuvin 479 (BASF Corporation), Tinuvin 1577FF (BASF Corporation), etc. Among them, 2,4-bis(2,4-dimethylphenyl)-6-[ can be used more preferably in terms of its high compatibility with acrylic resin and excellent ultraviolet absorption properties. 2-Hydroxy-4-(3-alkoxy-2-hydroxypropoxy)-5-α-cumylphenyl]-skeleton ("alkoxy" means octyloxy, nonyl Oxygen, decyloxy and other long-chain alkoxy groups) UV absorber. The ultraviolet absorber is preferably a benzotriazole-based compound or a benzotriazole-based compound with a molecular weight of 400 or more, especially from the viewpoint of compatibility with resin and volatility when heated. In addition, it inhibits ultraviolet rays. From the viewpoint that the absorbent itself is decomposed by heating during extrusion processing, benzotribenzotrifluoroethylene-based compounds are particularly preferred. Moreover, the melting point (Tm) of the ultraviolet absorber is preferably 80°C or higher, more preferably 100°C or higher, further preferably 130°C or higher, still more preferably 160°C or higher. The weight loss rate of the above ultraviolet absorber when the temperature is raised from 23°C to 260°C at a rate of 20°C/min is preferably 50% or less, more preferably 30% or less, further preferably 15% or less, still more preferably It is 10% or less, and more preferably, it is 5% or less. Only one type of these ultraviolet absorbers may be used alone, or two or more types may be used in combination. By combining two types of ultraviolet absorbers with different structures, ultraviolet rays in a wide range of wavelengths can be absorbed. The content of the above-mentioned ultraviolet absorber is not particularly limited as long as it is an amount that does not hinder heat resistance, moisture-heat resistance, thermal stability, and molding processability and exhibits the effects of the present invention. It is based on 100% by mass of the methacrylic resin. , preferably 0.1 to 5 mass%, preferably 0.2 to 4 mass% or less, more preferably 0.25 to 3 mass%, and still more preferably 0.3 to 3 mass%. If it is within this range, the balance of ultraviolet absorption performance, formability, etc. will be excellent.

--Release agent-- The resin composition constituting the resin lens for a head-mounted display according to this embodiment may contain a release agent. Examples of the release agent include fatty acid esters, fatty acid amide, fatty acid metal salts, hydrocarbon lubricants, alcohol lubricants, polyalkylene glycols, carboxylic acid esters, and chains of hydrocarbons. Alkane-based mineral oil, etc., but is not limited thereto.

The fatty acid ester that can be used as the release agent is not particularly limited, and conventionally known ones can be used. Examples of fatty acid esters that can be used include fatty acids with 12 to 32 carbon atoms such as lauric acid, palmitic acid, heptadecanoic acid, stearic acid, oleic acid, arachidic acid, and behenic acid, and palmitol, stearyl alcohol, and behenyl alcohol. Ester compounds of monovalent aliphatic alcohols such as alcohol or polyvalent aliphatic alcohols such as glycerol, pentaerythritol, dipentaerythritol, sorbitan anhydride; complex ester compounds of fatty acids and polyvalent organic acids, and monovalent aliphatic alcohols or polyvalent aliphatic alcohols, etc.

Examples of such fatty acid esters include cetyl palmitate, butyl stearate, stearyl stearate, stearyl citrate, glyceryl monocaprylate, glyceryl monocaprate, and lauryl monolaurate. Glyceryl monooleate, glyceryl dipalmitate, glyceryl monostearate, glyceryl distearate, glyceryl tristearate, glyceryl monooleate, glyceryl dioleate, glyceryl tristearate Glyceryl oleate, glyceryl monolinoleate, glyceryl monobehenate, glyceryl mono-12-hydroxystearate, glyceryl di-12-hydroxystearate, glyceryl tri-12-hydroxystearate, Acetyl glyceryl monostearate, citric acid fatty acid glyceryl ester, pentaerythritol adipate stearate, montanic acid partially saponified ester, pentaerythritol tetrastearate, dipentaerythritol hexastearate, sorbitan tristearate Fatty acid esters, etc. These fatty acid esters can be used individually by 1 type, or in combination of 2 or more types. Examples of commercially available products include the RIKEMAL series, POEM series, RIKESTER series, and RIKEMASTER series manufactured by Riken Vitamin Co., Ltd., and the EXCEL series, RHEODOL series, EXEPARL series, and COCONARD series manufactured by Kao Corporation. More specifically, examples thereof include RIKEMAL S-100, RIKEMAL H-100, POEM V-100, RIKEMAL B-100, RIKEMAL HC-100, RIKEMAL S-200, POEM B-200, RIKESTER EW-200, RIKESTER EW-400, EXCEL S-95, RHEODOL MS-50 etc.

The fatty acid amide is not particularly limited, and conventionally known ones can be used. Examples of fatty acid amide include: saturated fatty acid amide such as lauric acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide; oleic acid amide, mustardamide Unsaturated fatty acid amide such as acid amide, ricinoleic acid amide; N-stearyl stearyl amide, N-oleyl oleyl amide, N-stearyl oleyl amide, N-oleyl amide Substituted amide such as stearic acid amide, N-stearyl erucic acid amide, N-oleyl palmitamide and other amide; hydroxymethyl stearic acid amide such as hydroxymethyl stearic acid amide and hydroxymethyl behenic acid amide amide; methylene distearyl amide, ethyl distearyl amide, ethyl bislauric acid amide, ethyl distearyl amide (ethyl distearyl amide) ), ethylbisisostearamide, ethylbishydroxystearamide, ethylbisbehenate, hexamethylenebisstearamide, hexamethylenebisstearamide Saturated fatty acids such as behenic acid amide, hexamethylene bishydroxystearic acid amide, N,N'-distearyl adipamide, N,N'-distearyl sebacic acid amide Bisamide; Ethyl bisoleamide, hexamethylene bisoleamide, N,N'-dioleyl adipamide, N,N'-dioleyl sebacamide and other unsaturated fatty acid bisamides; aromatic bisamides such as m-xylylenedimethyl distearamide, N,N'-distearyl isophthalic acid camide, etc. These fatty acid amide can be used individually by 1 type, or in combination of 2 or more types. Examples of commercially available products include DIAMIDO series (manufactured by Nippon Kasei Co., Ltd.), amide series (manufactured by Nippon Kasei Co., Ltd.), Nikka amide series (manufactured by Nippon Kasei Co., Ltd.), hydroxymethylamide series, bisamide series, Slipax series (manufactured by Nippon Kasei Co., Ltd.), KAOWAX series (manufactured by Kao Co., Ltd.), fatty acid amide series (manufactured by Kao Co., Ltd.), ethylidene distearamide series (manufactured by Dainichi Chemical Industry Co., Ltd.), etc.

Fatty acid metal salts refer to metal salts of higher fatty acids, for example, lithium stearate, magnesium stearate, calcium stearate, calcium laurate, calcium ricinoleate, strontium stearate, barium stearate, laurel Barium acid, barium ricinoleate, zinc stearate, zinc laurate, zinc ricinoleate, zinc 2-ethylhexonate, lead stearate, lead dibasic stearate, lead naphthenate, 12 -Calcium hydroxystearate, lithium 12-hydroxystearate, etc., among which calcium stearate, lithium lithium stearate, etc. are particularly preferred in terms of the transparent resin composition obtained having excellent processability and extremely excellent transparency. Magnesium fatty acid, zinc stearate. Examples of commercially available products include SZ series, SC series, SM series, SA series, etc. manufactured by Sakai Chemical Industry Co., Ltd. From the viewpoint of maintaining transparency, when using the fatty acid metal salt, the content is preferably 0.2 mass% or less based on 100 mass% of the resin composition.

The above-mentioned release agent may be used individually by 1 type, and may be used in combination of 2 or more types.

As a release agent to be used, one with a decomposition start temperature of 200°C or higher is preferred. Among them, the decomposition start temperature can be measured by using the 1% mass loss temperature of TGA (Thermal gravimetry analysis, thermogravimetry analysis).

The content of the release agent only needs to be an amount that can achieve the effect of the release agent. If the content is excessive, there is a risk of bleeding during processing or screw slippage, resulting in poor extrusion. Therefore, compared to A 100 mass% of base acrylic resin, preferably 5 mass% or less, more preferably 3 mass% or less, further preferably 1 mass% or less, further preferably 0.8 mass% or less, still more preferably 0.01 to 0.8 mass% %, preferably 0.01 to 0.5 mass%. Adding it in an amount within the above range is preferable because it tends to suppress a decrease in transparency due to the addition of a release agent and also suppresses mold release failure during injection molding.

-Other thermoplastic resins- For the purpose of adjusting the birefringence or improving the flexibility without impairing the object of the present invention, the resin composition constituting the resin lens for the head-mounted display of this embodiment may also contain other thermoplastics besides methacrylic resin. resin.

Examples of other thermoplastic resins include polyacrylates such as polybutyl acrylate; polystyrene, styrene-methyl methacrylate copolymer, styrene-butyl acrylate copolymer, and styrene-acrylonitrile copolymer. styrenic polymers such as acrylonitrile-butadiene-styrene block copolymer; further, for example, Japanese Patent Laid-Open No. Sho 59-202213, Japanese Patent Laid-Open No. Sho 63-27516, Japanese Patent Laid-Open No. Sho 63-27516, Japanese Patent Laid-Open No. Acrylic rubber particles with a 3- to 4-layer structure described in Japanese Patent Application Publication No. 51-129449 and Japanese Patent Application Publication No. 52-56150; Japanese Patent Application Publication No. 60-17406 and Japanese Patent Application Publication No. 8-245854 The rubbery polymer disclosed in the publication; the graft copolymer particles containing methacrylic rubber obtained by multi-stage polymerization described in International Publication No. 2014-002491, etc. Among them, from the viewpoint of obtaining good optical properties and mechanical properties, a styrene-acrylonitrile copolymer or one having a graft portion on the surface layer and the graft portion is composed of a polymer that can contain a ring structure with the main chain is preferred. Rubber-containing graft copolymer particles composed of a composition compatible with the methacrylic resin of the structural unit (X).

The average particle diameter of the acrylic rubber particles, graft copolymer particles containing methacrylic rubber, and rubbery polymer is from the viewpoint of improving the impact strength and optical properties of the film obtained from the composition of this embodiment. Specifically, 0.03 to 1 μm is preferred, and 0.05 to 0.5 μm is more preferred.

As content of other thermoplastic resin, when the methacrylic resin is 100 mass %, 0-50 mass % is preferable, and 0-25 mass % is more preferable.

[Production method of resin composition] The manufacturing method of the resin composition constituting the resin lens for a head-mounted display according to this embodiment is not particularly limited as long as a composition that satisfies the requirements of the present invention can be obtained. For example, a method of kneading using a kneading machine such as an extruder, a heating roller, a kneader, a roller mixer, or a Bambry mixer can be used. Among them, kneading using an extruder is preferred in terms of productivity. The kneading temperature only needs to be based on the optimal processing temperature of the polymer constituting the methacrylic resin or other resins to be mixed. As a standard, it is in the range of 140 to 300°C, and preferably in the range of 180 to 280°C. In addition, for the purpose of reducing volatile matter, it is preferable to provide an exhaust port in the extruder.

Here, in the resin composition constituting the resin lens for a head-mounted display according to this embodiment, the amount of residual solvent (amount of residual solvent) is preferably less than 1000 mass ppm, more preferably less than 800 mass ppm, and further Preferably, it is less than 700 mass ppm. Here, the remaining solvent refers to the polymerization solvent used during polymerization (excluding alcohols) and the solvent used when the resin obtained by polymerization is dissolved again to solubilize it. Specifically, as a polymerization solvent , examples include: aromatic hydrocarbons such as toluene, xylene, ethylbenzene, and cumene; ketones such as methyl isobutyl ketone, butyl cellosolve, methyl ethyl ketone, and cyclohexanone; dimethylmethane Polar solvents such as amide and 2-methylpyrrolidone; examples of solvents used for redissolution include toluene, methyl ethyl ketone, methylene chloride, and the like.

The amount of alcohol remaining in the resin composition constituting the resin lens for a head-mounted display according to this embodiment (amount of residual alcohol) is preferably less than 500 ppm by mass, more preferably less than 400 ppm by mass, and even more preferably less than 500 ppm by mass. 350 mass ppm. Here, the remaining alcohol refers to an alcohol by-produced by the cyclization condensation reaction, and specific examples include aliphatic alcohols such as methanol, ethanol, and isopropyl alcohol.

The above-mentioned residual solvent amount and the above-mentioned residual alcohol amount can be measured by gas chromatography.

When either method is chosen, it is preferred to prepare the composition after reducing oxygen and water as much as possible. For example, in solution polymerization, the dissolved oxygen concentration in the polymerization solution is preferably less than 300 ppm in the polymerization step, and in a production method using an extruder, etc., the oxygen concentration in the extruder is, It is preferable that it is less than 1 volume %, and it is further more preferable that it is less than 0.8 volume %. The moisture content of the methacrylic resin is preferably adjusted to 1000 ppm by mass or less, more preferably 500 ppm by mass or less. Within these ranges, it is relatively easy to prepare a composition that satisfies the necessary conditions of the present invention, which is advantageous.

[Manufacturing method of resin lenses for head-mounted displays] The resin lens for a head-mounted display according to this embodiment is formed by molding the above-mentioned resin composition. As a method of manufacturing the resin lens for a head-mounted display according to this embodiment, a molding method such as injection molding, compression molding, or extrusion molding can be used. Among them, from the viewpoint of productivity, injection molding is preferred.

Generally, the injection molding method includes the following steps: (1) melting the resin and filling the molten resin into the mold cavity of the temperature-controlled mold; (2) applying pressure to the mold cavity until the gate is sealed, and then injecting The pressure-holding step is equivalent to the amount of resin that shrinks when the molten resin filled in the injection step contacts the mold and cools down; (3) After releasing the pressure-holding, the cooling step is to hold the molded product until the resin cools down; (4) Open the mold and take it out Steps for cooling the molded product.

At this time, the molding temperature is in the range of Tg+100°C to Tg+160°C based on the glass transition temperature (Tg) of the resin composition, and preferably in the range of Tg+110°C to Tg+150°C. Here, the molding temperature refers to the control temperature of the tape heater wound around the injection nozzle. Although it is possible to obtain a resin lens with a lower phase difference as the molding temperature is higher, discoloration caused by thermal deterioration during retention in the molding machine will be promoted at a constant temperature, so the molding temperature should be appropriately selected. In addition, the mold temperature is preferably in the range of Tg-70°C to Tg based on the glass transition temperature (Tg) of the resin composition, and more preferably in the range of Tg-50°C to Tg-20°C.

In addition, the injection speed can be appropriately selected according to the thickness or size of the resin lens to be obtained, and can be appropriately selected from the range of 5 to 1000 mm/second, for example. In addition, the pressure used to maintain the pressure can be appropriately selected according to the shape of the resin lens to be obtained, and can be appropriately selected in the range of 30 to 120 MPa, for example. Here, the pressure used to maintain the pressure refers to the pressure maintained by a screw that is used to send out the molten resin from the gate after filling the molten resin.

In addition, in order to relax the residual stress generated by injection molding and reduce the phase difference of the resin lens, an annealing step may also be performed. The temperature during annealing is based on the glass transition temperature (Tg) of the resin composition, and is preferably in the range of Tg-50°C to Tg, more preferably in the range of Tg-30°C to Tg-10°C.

The surface of the resin lens for a head-mounted display according to this embodiment may further be subjected to surface functionalization treatments such as hard coating treatment, anti-reflection treatment, transparent conductive treatment, electromagnetic wave shielding treatment, and gas barrier treatment. The thickness of these functional layers is not particularly limited, and is usually in the range of 0.01 to 10 μm.

As a hard coat layer provided on the surface, for example, silicone-based curable resin, curable resin containing organic polymer composite inorganic fine particles, polyurethane acrylate, epoxy acrylate, polyfunctional An acrylic ester such as acrylic acid ester and a photopolymerization initiator are dissolved or dispersed in an organic solvent, and the coating liquid thus obtained is applied to the film or sheet obtained from the resin composition of the present embodiment by a conventionally known coating method. On the material, let it dry, and let it light harden to form. In addition, before applying the hard coat layer, in order to improve the adhesion, it is also possible to form the hard coat layer by pre-providing an easy-adhesion layer, a primer layer, an adhesion layer, etc. containing inorganic particles. As an anti-glare layer provided on the surface, fine particles such as silicon dioxide, melamine resin, and acrylic resin are converted into inks, and are coated on other functional layers using a conventionally known coating method, and are exposed to heat or light. formed by hardening. Examples of the anti-reflective layer provided on the surface include thin films containing inorganic substances such as metal oxides, fluorides, silicides, boride, nitrides, and sulfides, and resins having different refractive indexes such as acrylic resins and fluororesins. A single layer or a plurality of layers may be laminated. Alternatively, a thin layer of composite fine particles including an inorganic compound and an organic compound may be laminated. [Example]

Hereinafter, the contents of the present invention will be specifically described with reference to Examples and Comparative Examples. In addition, this invention is not limited to the following Example.

<1. Determination of the amount of 2-cyclohexylamino-N-cyclohexylmaleimide in N-cyclohexylmaleimide> Take and weigh N-cyclohexylmaleimide or N-cyclohexylmaleimide/m-xylene solution to prepare 25 mass% m-xylene of N-cyclohexylmaleimide. Toluene solution was determined by adding isopropyl benzoate as an internal standard substance and measuring it under the following conditions using gas chromatography (GC-2014 manufactured by Shimadzu Corporation). Detector: FID (Flame Ionization Detector, Flame Ionization Detector) Use column: HP-5ms Measurement conditions: After maintaining at 80°C for 5 minutes, raise the temperature to 300°C at a heating rate of 10°C/min, and then maintain it for 5 minutes.

<2. Determination of the amount of 2-anilino-N-phenylsuccinimide in N-phenylmaleimide> Take and weigh N-phenylmaleimide or N-phenylmaleimide/m-xylene solution to prepare 10 mass% m-xylene of N-phenylmaleimide. Toluene solution was determined by adding isopropyl benzoate as an internal standard substance and measuring it under the following conditions using liquid chromatography (UPLC H-class manufactured by Waters Co., Ltd.). Detector: PDA (photo-diode array, photodiode array) (detection wavelength: 210 nm ~ 300 nm) Column used: ACQUITY UPLC HSS T3 Tube string temperature: 40℃ Mobile phase: 50% acetonitrile aqueous solution containing 0.1% formic acid Flow rate: 0.4 mL/min

<3. Determination of the remaining amount of N-substituted maleic imine monomer> Collect and weigh a part of the analysis target (polymerization solution after polymerization, or methacrylic resin particles), dissolve the sample in chloroform, prepare a 5% by mass solution, add n-decane as an internal standard material, and use the gas phase The chromatography method (GC-2010 manufactured by Shimadzu Corporation) was determined by measuring under the following conditions. Detector: FID Use column: ZB-1 Measurement conditions: After maintaining at 45°C for 5 minutes, raise the temperature to 300°C at a heating rate of 20°C/min, and then maintain it for 15 minutes.

<4. Analysis of structural units> Regarding each structural unit in the methacrylic resin produced in the following production examples and comparative examples, unless otherwise specified in advance, each structural unit was measured by ¹ H-NMR and ¹³ C-NMR. Measurement: Each structural unit is identified for the methacrylic resin and the methacrylic resin composition, and its presence amount is calculated. The measurement conditions for ¹ H-NMR measurement and ¹³ C-NMR measurement are as follows.・Measurement machine: JNM-ECZ400S manufactured by Japan Electronics Co., Ltd. ・Measurement solvent: CDCl ₃ or d ₆ -DMSO ・Measurement temperature: 40°C

＜5.Molecular weight and molecular weight distribution＞ The weight average molecular weight (Mw), number average molecular weight (Mn), and Z average molecular weight (Mz) of the methacrylic resin composition produced in the following production examples and production comparative examples were measured using the following equipment and conditions. . ・Measuring device: Gel permeation chromatography (HLC-8320GPC) manufactured by Tosoh Co., Ltd. ・Measurement conditions: Column: Connect 1 TSKguardcolumn SuperH-H, 2 TSKgel SuperHM-M, and 1 TSKgel SuperH2500 in series. Tube string temperature: 40℃ Development solvent: tetrahydrofuran, flow rate: 0.6 mL/min, as an internal standard, 2,6-di-tert-butyl-4-methylphenol (BHT) was added at 0.1 g/L. Detector: RI (differential refraction) detector Detection sensitivity: 3.0 mV/min Sample: 0.02 g of methacrylic resin composition in 20 mL of tetrahydrofuran solution Injection volume: 10 μL Standard samples for calibration curve: Use the following 10 polymethyl methacrylates (manufactured by Polymer Laboratories; PMMA Calibration Kit M-M-10) with known monodisperse weight peak molecular weights and different molecular weights. Weight peak molecular weight (Mp) Standard sample 1 1,916,000 Standard sample 2 625,500 Standard sample 3 298,900 Standard sample 4 138,600 Standard sample 5 60,150 Standard sample 6 27,600 Standard sample 7 10,290 Standard sample 8 5,000 Standard sample 9 2,810 Standard sample 10 850 The RI detection intensity of the methacrylic resin composition relative to the dissolution time was measured under the above conditions. Based on each calibration curve obtained by measuring the standard sample for the above calibration curve, the weight average molecular weight (Mw), number average molecular weight (Mn), and Z average molecular weight (Mz) of the methacrylic resin composition were determined. , use this value to determine the molecular weight distribution (Mw/Mn) and (Mz/Mw).

<6. Phase difference within the effective diameter of the resin lens> For the resin lenses obtained in the Examples and Comparative Examples, the birefringence evaluation system PA-200-L manufactured by Photonic Lattice was used to measure the surface distribution of the phase difference of the lens from the optical axis direction at a wavelength of 520 nm, and the lens was designated Find the average value of the absolute value of the phase difference (nm) within the area within the effective diameter (Φ41 mm).

<7. Content of the fluorescent substance in the resin lens> The resin lens obtained in the Examples and Comparative Examples was chopped, weighed in a glass sample bottle, chloroform was added, and a shaker was used to rotate the resin lens at 800 rpm per minute. The solution was shaken at the next speed for 30 minutes to prepare a 2.0 mass% chloroform solution of the resin lens, and the fluorescence intensity was measured using a fluorescence spectrophotometer (Fluorolog 3-22, manufactured by HORIBA Jobin Yvon). Regarding the measurement conditions, a xenon lamp was used as the light source, a PMT (Photomultiplier Tube, photomultiplier tube) was used as the detector, the excitation wavelength was set to 436 nm, the slit width was set to 2 nm on both the excitation side and the observation side, and the time constant is 0.2 s, the measurement mode is set to Sc/Rc, which normalizes the luminescence intensity using the excitation light intensity of each wavelength, and the measurement is performed using a quartz cell with an optical path length of 1 cm and observation at 90°. The obtained fluorescence intensity at a wavelength of 530 nm was normalized using the fluorescence intensity of the luciferin/ethanol solution. Specifically, proceed as follows. Calculate the fluorescence at the wavelength of 530 nm when performing spectroscopic analysis of ethanol, 5×10 ^-8 mol/L and 1×10 ^-6 mol/L luciferin/ethanol solutions at an excitation wavelength of 436 nm. Intensity, after subtracting the background of ethanol, is converted into a concentration-intensity conversion formula. To measure the fluorescence spectrum of chloroform, the luminescence intensity obtained by subtracting the 530 nm wavelength luminescence intensity of chloroform from the 530 nm wavelength luminescence intensity of the 2.0 mass% chloroform solution of the resin lens is used. Use the previously determined concentration of the luciferin/ethanol solution. -Convert the intensity conversion formula into concentration and obtain the content (mol/L) of the fluorescent substance.

＜8. Glass transition temperature of resin lens＞ The glass transition temperature (Tg) (°C) of the resin lens is measured in accordance with JIS-K7121. First, cut out 4 parts (4 parts) of approximately 10 mg each from a resin lens that has been conditioned (left at 23°C for 1 week) under standard conditions (23°C, 50%RH) and used as test pieces. Next, a differential scanning calorimeter (Diamond DSC manufactured by PerkinElmer Japan) was used at a nitrogen flow rate of 25 mL/min. Here, the temperature was raised from room temperature (23°C) at 10°C/min (one temperature increase) to 200°C, keep it at 200°C for 5 minutes, and after the sample is completely melted, raise the temperature from 200°C to 40°C at 10°C/min, keep it at 40°C for 5 minutes, and then measure the temperature rise again under the above heating conditions (2 The intersection point (middle) of the step-like change part of the DSC (Differential Scanning Calorimetry) curve drawn during the second temperature rise and the straight line equidistant from the extension line of each baseline in the vertical axis direction (middle Point glass transition temperature) as glass transition temperature (Tg) (°C). Four measurements were made for each sample, and the arithmetic mean of the four measurements (rounded off to the nearest decimal point) was used as the measured value.

<9. Photoelastic coefficient of resin lens> The resin lens obtained in the Examples and Comparative Examples was chopped into pieces and then pressed into a film using a vacuum compression molding machine to prepare a measurement sample. As specific sample preparation conditions, a vacuum compression molding machine (SFV-30 model manufactured by Shinto Metal Industry Co., Ltd.) was used to preheat the resin lens at 260°C for 10 minutes under reduced pressure (approximately 10 kPa). , compress it at about 10 MPa for 5 minutes, release the pressure reduction and pressure increase, and then move it to a cooling compression molding machine to cool and solidify. After the obtained pressed film is cured for more than 24 hours in a constant temperature and humidity room adjusted to 23°C and a humidity of 60%, a test piece for measurement (thickness approximately 150 μm, width 6 mm) is cut out. The photoelastic coefficient _CR (Pa ^-1 ) was measured using the birefringence measuring device described in detail in Polymer Engineering and Science 1999, 39, 2349-2357. The film-shaped test piece was placed on a film stretching device (manufactured by Imoto Seisakusho) that was also installed in a constant temperature and humidity chamber so that the distance between the clamps was 50 mm. Then, the birefringence measuring device (RETS-100 manufactured by Otsuka Electronics) was arranged so that the laser light path was located in the center of the film, and the strain rate was 50%/min (between chucks: 50 mm, chuck moving speed). : 5 mm/min), apply tensile stress, and measure the birefringence of the test piece on one side. By the least squares approximation method, the slope of the straight line is found based on the relationship between birefringence (Δn) and tensile stress (σ _R ) obtained by measurement, and the photoelastic coefficient ( _CR ) (Pa ^-1 ) is calculated. The calculation uses data with tensile stress between 2.5 MPa≦σ _R ≦10 MPa. C _R =Δn/σ _R where birefringence (Δn) is the value shown below. Δn=nx-ny (nx: refractive index in the stretching direction, ny: refractive index in the direction perpendicular to the stretching direction)

＜10.Transmittance of resin lens＞ For the resin lenses obtained in Examples and Comparative Examples, a spectrophotometer (SD-5000, manufactured by Nippon Denshoku Industries Co., Ltd.) was used to allow light to pass through the thickest part of the lens in the thickness direction, and the D65 light source 10 °Measure the transmittance (%) every 5 nm in the wavelength range of 380 to 780 nm in the visual field. Using the measured values, find the ratio (T450/T680) of the transmittance at a wavelength of 450 nm (T450) to the transmittance at a wavelength of 680 nm (T680).

＜11. Image clarity＞ Using the resin lenses obtained in Examples and Comparative Examples, a simulation device that reproduces the principle of a head-mounted display described in Japanese Patent Application Laid-Open No. 2017-21321 as shown in Figure 1 was produced in a darkroom. In this simulation device, a liquid crystal display 1, a polarizing plate 2, a quarter-wavelength plate 3, a half-mirror 4, a resin lens 5 obtained in Examples and Comparative Examples, a quarter-wavelength plate 6, and a reflective The polarizing plates 7 are arranged coaxially in sequence. When the light along the optical axis from the liquid crystal display 1 passes through the polarizing plate 2, the 1/4 wavelength plate 3, the half mirror 4, the resin lens 5, and the 1/4 wavelength plate 6 and reaches the reflective polarizing plate 7, it is reflected polarized light. Reflected by the plate 7 (first reflection), and then passes through the 1/4 wavelength plate 6 and the resin lens 5 to reach the half mirror 4, is reflected by the half mirror 4 (the second reflection), and passes through the resin lens 5 and The 1/4 wavelength plate 6 and the reflective polarizing plate 7 reach the human eye. Furthermore, the half-reflecting mirror 4 can reflect part of the light and transmit the remaining light. Every time light passes through a quarter wave plate, a phase retardation of 90 degrees is added. The image is amplified by the above-mentioned secondary reflections and reaches the human eye. The still image displayed on the liquid crystal display 1 through the above simulation device was observed, and the sharpness of the image was evaluated based on the following evaluation criteria. [Evaluation criteria] 〇: The image is enlarged and no haze or blur is observed. △: The lower magnification image overlaps with the enlarged image, making the image slightly unclear. ×: It is mainly observed that images with low magnification become unclear.

[raw material] The raw materials used in the following Examples and Comparative Examples are as follows. [[Single body]] ・Methyl methacrylate (MMA): manufactured by Asahi Kasei Co., Ltd. ・N-cyclohexylmaleimide (chMI): manufactured by Nippon Shokubai Co., Ltd. (The mass ratio of 2-cyclohexylamino-N-cyclohexylsuccinimide (CCSI) to the mass of chMI is 80 mass ppm) ・N-phenylmaleimide (phMI): manufactured by Nippon Shokubai Co., Ltd. (The mass ratio of 2-anilino-N-phenylsuccinimide (APSI) to the mass of phMI is 60 ppm by mass)

-Pre-treatment of N-substituted maleimide (chMI, phMI) (water washing step and dehydration step)- For the above-mentioned N-cyclohexylmaleimide (chMI) and N-phenylmaleimide (phMI), 2-amino-N-substituted butane is carried out through the following water washing and dehydration steps. Removal of diimide (CCSI, APSI) and removal of moisture.

--Water washing and dehydration of N-cyclohexylmaleimide (chMI)----Reduce the CCSI in N-cyclohexylmaleimide to less than 5 mass ppm---Measurement 250.0 kg of chMI and 750.0 kg of xylene (hereinafter referred to as "mXy") were added to a 2.0 m3 glass-lined system equipped with a temperature control device using a jacket and ^three swept blades as stirring blades. In the reactor, steam was blown into the jacket to raise the temperature of the solution in the reactor to 56°C, and stirred to obtain an organic layer. Next, 350.0 kg of 2 mass% sulfuric acid water was measured and added to the reactor, and the solution temperature was maintained at 56° C. and stirred at 100 rpm for 10 minutes. Stop stirring, let it stand for 10 minutes, and pump the water layer into the storage drum. Furthermore, the same operation was repeated twice, and the organic layer was washed with sulfuric acid water a total of three times. The amount of CCSI in the organic layer was quantified using gas chromatography, and the result was 4.9 ppm by mass relative to the chMI in the organic layer. Thereafter, 350.0 kg of ion-exchange water was added to the reactor, the solution temperature was maintained at 55°C, and the mixture was stirred at 100 rpm for 10 minutes. Stop stirring, let it stand for 20 minutes, and pump the water layer into a storage drum. The same operation was repeated again, and the organic layer was washed with ion-exchange water twice in total. The amount of CCSI in the organic layer was quantified using gas chromatography, and the result was 4.6 ppm by mass relative to the chMI in the organic layer. Secondly, while maintaining the solution temperature at 50°C, while stirring at 100 rpm, the pressure in the reactor was gradually reduced to 5 kPa. Thereafter, the solution temperature was raised to 60°C, and azeotropic dehydration was performed. 131.6 kg of water/mXy mixture was distilled away, and the moisture concentration in the organic layer was quantified using a Karl Fischer moisture analyzer. The result was 102 mass ppm relative to the mass of the organic layer. mXy for concentration adjustment was added to the organic layer to obtain 1034.3 kg of an organic layer with a chMI of 24.0 mass %, a water concentration of 191 mass ppm, and a CCSI of 4.6 mass ppm relative to the chMI.

---Reduce the CCSI in N-cyclohexylmaleimide to less than 1 mass ppm ---Measure 80.0 kg of chMI and 240.0 kg of mXy, and add them to a temperature regulating device equipped with a jacket In a 0.50 ^m3 glass-lined reactor made of FULLZONE manufactured by KOBELCO ECO-SOLUTIONS as a stirring blade, steam was blown into the jacket to raise the temperature of the solution in the reactor to 55°C, and the organic layer was obtained by stirring. . Next, 112.0 kg of 2 mass % sulfuric acid water was measured and added to the reactor, and the solution temperature was maintained at 55° C. and stirred at 100 rpm for 30 minutes. Stop stirring, let it stand for 10 minutes, and pump the water layer into the storage drum. The same operation was repeated three times, and the organic layer was washed with sulfuric acid water a total of four times. The amount of CCSI in the organic layer was quantified using gas chromatography, and the result was 0.57 ppm by mass relative to the chMI in the organic layer. Thereafter, 112.0 kg of ion-exchange water was added to the reactor, the solution temperature was maintained at 55°C, and the mixture was stirred at 100 rpm for 30 minutes. Stop stirring, let it stand for 10 minutes, and pump the water layer into the storage drum. Keep the temperature of the solution at 50°C, while stirring at 100 rpm, gradually reduce the pressure in the reactor and set the pressure in the reactor to 5 kPa. Thereafter, the solution temperature was raised to 60°C, and azeotropic dehydration was performed. 54 kg of the water/mXy mixture was distilled away, and the moisture concentration in the organic layer was quantified using a Karl Fischer moisture analyzer. The result was 46 ppm by mass relative to the mass of the organic layer. mXy for concentration adjustment was added to the organic layer to obtain 384.0 kg of an organic layer with a chMI of 20.3 mass %, a water concentration of 125 mass ppm, and a CCSI of 0.60 mass ppm relative to the mass of chMI.

--Washing and dehydration of N-phenylmaleimide (phMI)----Reducing APSI in N-phenylmaleimide to less than 5 mass ppm---Measurement 150.0 kg of phMI and 720.0 kg of mXy were added to a 2.0 ^m3 glass-lined reactor equipped with a temperature control device using a jacket and three swept blades as stirring blades, and steam was blown into the jacket. The temperature of the solution in the reactor was raised to 55°C and stirred to obtain an organic layer. Next, 336.0 kg of 7 mass% sodium bicarbonate water was measured and added to the reactor, and the solution temperature was maintained at 55° C. and stirred at 100 rpm for 10 minutes. Stop stirring, let it stand for 10 minutes, and pump the water layer into the storage drum. Next, 336.0 kg of ion-exchange water was added to the reactor, the solution temperature was maintained at 55°C, and the mixture was stirred at 100 rpm for 10 minutes. Stop stirring, let it stand for 10 minutes, and pump the water layer into the storage drum. Thereafter, 336.0 kg of 2 mass% sulfuric acid water was measured and added to the reactor, and the solution temperature was maintained at 55° C. and stirred at 100 rpm for 10 minutes. Stop stirring, let it stand for 10 minutes, and pump the water layer into the storage drum. Washing with ion-exchange water was performed twice in the same manner as above. The amount of APSI in the organic layer was quantified using liquid chromatography, and the result was 3.6 ppm by mass relative to the phMI in the organic layer. Secondly, while maintaining the solution temperature at 50°C, while stirring at 100 rpm, the pressure in the reactor was gradually reduced to 5 kPa. Thereafter, the solution temperature was raised to 55°C, and azeotropic dehydration was performed. 190 kg of the water/mXy mixture was distilled away, and the moisture concentration in the organic layer was quantified using a Karl Fischer moisture analyzer. The result was 47 ppm by mass relative to the mass of the organic layer. mXy for concentration adjustment was added to the organic layer to obtain 1340.7 kg of the organic layer in which phMI was 10.8 mass %, the water concentration was 170 mass ppm, and the mass APSI relative to phMI was 3.4 mass ppm.

---Reduce APSI in N-phenylmaleimide to less than 1 ppm by mass --- Measure 50.0 kg of phMI and 240.0 kg of mXy, and add them to a temperature regulating device equipped with a jacket In a 0.50 ^m3 glass-lined reactor made of FULLZONE manufactured by KOBELCO ECO-SOLUTIONS as a stirring blade, steam was blown into the jacket to raise the temperature of the solution in the reactor to 55°C, and the organic layer was obtained by stirring. . Next, 112.0 kg of 7 mass% sodium bicarbonate water was measured and added to the reactor, and the solution temperature was maintained at 55° C. and stirred at 100 rpm for 15 minutes. Stop stirring, let it stand for 10 minutes, and pump the water layer into the storage drum. The same operation was repeated again, and the organic layer was washed with sodium bicarbonate water twice in total. Next, 112.0 kg of ion-exchange water was added to the reactor, the solution temperature was maintained at 55°C, and the mixture was stirred at 100 rpm for 30 minutes. Stop stirring, let it stand for 10 minutes, and pump the water layer into the storage drum. Thereafter, 112.0 kg of 2 mass % sulfuric acid water was measured and added to the reactor, and the solution temperature was maintained at 55° C. and stirred at 100 rpm for 30 minutes. Stop stirring, let it stand for 10 minutes, and pump the water layer into the storage drum. Furthermore, the same operation was repeated twice, and the organic layer was washed with sulfuric acid water a total of three times. Washing with ion-exchange water was performed twice in the same manner as above. The amount of APSI in the organic layer was quantified using liquid chromatography, and the result was 0.37 ppm by mass relative to the phMI in the organic layer. Keep the temperature of the solution at 50°C, while stirring at 100 rpm, gradually reduce the pressure in the reactor and set the pressure in the reactor to 5 kPa. Thereafter, the solution temperature was raised to 55°C, and azeotropic dehydration was performed. 72 kg of water/mXy mixture was distilled away, and the moisture concentration in the organic layer was quantified using a Karl Fischer moisture analyzer. The result was 60 ppm by mass relative to the mass of the organic layer. mXy for concentration adjustment was added to the organic layer to obtain 432.8 kg of an organic layer in which phMI was 10.3 mass %, the water concentration was 180 mass ppm, and the APSI relative to the mass of phMI was 0.42 mass ppm.

[[Polymerization initiator]] ・1,1-Di(tert-butylperoxy)cyclohexane: "Perhexa C" manufactured by NOF Co., Ltd. [[Chain transfer agent]] ・N-octanethiol: manufactured by Kao Co., Ltd. [[Hindered phenol antioxidant]] ・Irganox 1010: Manufactured by BASF Corporation [[Phosphorus antioxidant]] ・Irgafos 168 (melting point 180~190°C): manufactured by BASF

[Methacrylic resin composition] [Manufacture Example 1] After the water washing step and the dehydration step, 374.8 kg of the 10.3 mass % mXy solution of phMI (APSI relative to the mass of phMI is 0.42 mass ppm) was measured, and after the water washing step and In the dehydration step, 323.6 kg of the 20.3 mass% mXy solution of chMI (the mass of CCSI relative to chMI is 0.60 mass ppm) was added to a 1.25 m ³ reactor equipped with a temperature control device using a jacket and a stirring blade. The solution was stirred at a temperature of 60°C and a pressure of 5 kPa in the reactor, while 160.8 kg of mXy was removed by distillation under reduced pressure. Then, the reaction kettle was returned to normal pressure, and mXy 16.7 kg was added to prepare a mixed solution of phMI 38.6 kg, chMI 65.7 kg, and mXy 450.0 kg. 445.7 kg of MMA and 0.413 kg of n-octanethiol as a chain transfer agent were measured, added and stirred to obtain a monomer mixed solution. To the content of the reactor, nitrogen gas was introduced at a rate of 30 L/min for 1 hour to remove dissolved oxygen. Thereafter, steam was blown into the jacket to raise the temperature of the solution in the reactor to 125°C. While stirring at 50 rpm, 1,1-bis(3-butyl) was added at a rate of 0.5 kg/hour. A polymerization initiator solution was prepared by dissolving 0.23 kg of cyclohexane (hydroxyperoxide) in 2.77 kg of mXy, thereby starting the polymerization. The addition was stopped 6 hours after the start of the polymerization. Furthermore, during the polymerization, the solution temperature in the reactor was controlled to 125±2°C by temperature adjustment using a jacket. After 8 hours passed from the start of polymerization, a polymerization solution containing a methacrylic resin having a ring structure in the main chain was obtained. The amount of N-substituted maleimide contained in the obtained polymerization solution was evaluated and found to be 1340 mass ppm of phMI and 4390 mass ppm of chMI. To this polymerization solution were added 0.1 mass % of Irganox 1010 and 0.05 mass % of Irgafos 168 with respect to 100 mass % of the polymer contained in the solution. The polymerization solution containing this antioxidant was filtered by passing it through a filter containing metal fibers made of SUS316L and having a filtration accuracy of 2 μm. In order to recover the polymer from the polymerization solution, as a device for the devolatization step, a flat plate heat exchanger with a flat plate slit flow path and a heat medium flow path, and an attached SUS (with an internal volume of about 0.3 ^m3 ) are used. A devolatilization device for decompression vessels (hereinafter referred to as devolatilization tanks) with heat medium jackets made of Steel Use Stainless. The solution containing the polymer obtained by polymerization was supplied to a heat exchanger installed on the upper part of the decompression vessel at a rate of 30 liters/hour, and after being heated to 260°C, the solution was maintained at an internal temperature of 260°C and a vacuum degree of 30 Torr. It is then supplied to a heated and depressurized devolatization tank to perform devolatization treatment. The shear rate in the devolatilization device was calculated based on the device shape and operating conditions, and the result was 5.3 s ^-1 . Use a gear pump to increase the pressure of the devolatized polymer from the lower part of the devolatilization tank, and extrude it from the strand die. After cooling with water, it is granulated to obtain methacrylic resin composition A. The composition of the methacrylic resin composition A was confirmed, and the results showed that the structural units derived from each monomer of MMA, phMI, and chMI were 81.2 mass %, 7.1 mass %, and 11.7 mass %, respectively. Moreover, the weight average molecular weight Mw is 148,000, Mw/Mn is 2.12, Mz/Mw is 1.63, and the glass transition temperature is 133 degreeC.

[Production Example 2] 352.4 kg of a 10.3 mass% mXy solution of phMI that has undergone the water washing step and the dehydration step (the mass of APSI relative to phMI is 0.42 mass ppm), and 20.3 mass% mXy of chMI that has gone through the water washing step and the dehydration step. 310.3 kg of the solution (the mass of CCSI relative to chMI is 0.60 ppm by mass) was added to a 1.25 m ³ reactor equipped with a temperature control device using a jacket and a stirring blade, while the solution temperature was 60°C and the pressure inside the reactor was maintained While stirring at 5 kPa, 335.4 kg of mXy was removed by distillation under reduced pressure. Then, the reaction kettle was returned to normal pressure, and mXy 8.9 kg was added to prepare a mixed solution of phMI 36.3 kg, chMI 63.0 kg, and mXy 236.9 kg. 340.7 kg of MMA and 0.275 kg of n-octanethiol as a chain transfer agent were measured, added and stirred to obtain a monomer mixed solution. Next, mXy 123.1 kg was measured and added to tank 1. Furthermore, 110.0 kg of MMA and 90.0 kg of mXy were measured in the tank 2 and stirred to prepare a monomer solution for addition. Nitrogen gas was introduced into the contents of the reactor at a rate of 30 L/min for 1 hour, and nitrogen gas was introduced into each of Tank 1 and Tank 2 at a rate of 10 L/min for 30 minutes to remove dissolved oxygen. Thereafter, steam was blown into the jacket to raise the temperature of the solution in the reactor to 128°C. While stirring at 50 rpm, 1,1-bis(tert-butyl) was added at a rate of 1 kg/hour. A polymerization initiator solution was prepared by dissolving 0.37 kg of cyclohexane (hydroxyperoxide) in 3.005 kg of mXy, thereby starting the polymerization. 0.5 hours after the start of polymerization, the addition rate of the starter solution was reduced to 0.25 kg/hour, and mXy was added from tank 1 at 35.2 kg/hour over 3.5 hours. Furthermore, during the polymerization, the solution temperature in the reactor was controlled to 128±2°C by temperature adjustment using a jacket. Then, 4 hours after the start of polymerization, the addition rate of the starter solution was changed to 0.75 kg/hour, and the monomer solution containing MMA was added from tank 2 at a rate of 100.0 kg/hour over 2 hours. Furthermore, 6 hours after the start of the polymerization, the addition rate of the starter solution was reduced to 0.5 kg/hour, and the addition was stopped 7 hours after the start of the polymerization. The polymerization was further continued for 1 hour, and a polymerization solution containing a methacrylic resin having a ring structural unit in the main chain was obtained. The amount of N-substituted maleimide contained in the obtained polymerization solution was evaluated and found to be 220 mass ppm of phMI and 1070 mass ppm of chMI. To this polymerization solution were added 0.1 mass % of Irganox 1010 and 0.05 mass % of Irgafos 168 with respect to 100 mass % of the polymer contained in the solution. The polymerization solution containing the antioxidant was filtered by passing it through a filter containing metal fibers made of SUS316L and having a filtration accuracy of 2 μm. In order to recover the polymer from the polymerization solution, as a device for the devolatization step, a flat-plate heat exchanger with a flat-plate slit flow path and a heat medium flow path, and an attached SUS-made heat exchanger with an internal volume of about 0.3 ^m3 are used. A heat medium jacketed decompression vessel (hereinafter referred to as a devolatization tank) and a devolatization device without a rotating part. The solution containing the polymer obtained by polymerization was supplied to a heat exchanger installed on the upper part of the decompression vessel at a rate of 30 liters/hour, and after being heated to 260°C, the solution was maintained at an internal temperature of 260°C and a vacuum degree of 30 Torr. It is then supplied to a heated and depressurized devolatization tank to perform devolatization treatment. The shear rate in the devolatilization device was calculated based on the device shape and operating conditions, and the result was 5.3 s ^-1 . A gear pump is used to increase the pressure of the devolatized polymer from the lower part of the devolatilization tank, and the polymer is extruded from a strand die, and then pelletized after cooling with water to obtain methacrylic resin composition B. The composition of the methacrylic resin composition B was confirmed. As a result, the structural units derived from each monomer of MMA, phMI, and chMI were 80.9 mass%, 7.0 mass%, and 12.1 mass%, respectively. Moreover, the weight average molecular weight Mw is 142,000, Mw/Mn is 2.32, Mz/Mw is 1.75, and the glass transition temperature is 134 degreeC.

[Manufacturing Example 3] A 10.8% by mass mXy solution of phMI that has undergone the water washing step and the dehydration step (the mass of APSI relative to phMI is 3.4 ppm by mass), and a 24.0 mass% mXy solution of chMI that has undergone the water washing step and the dehydration step (CCSI relative to chMI Methacrylic resin composition C was obtained in the same manner as in Production Example 2 except that the composition of the mixed solution prepared in the reactor was 4.6 ppm by mass). Furthermore, the amount of N-substituted maleimide contained in the obtained polymerization solution was evaluated and found to contain 210 mass ppm of phMI and 1090 mass ppm of chMI. The composition of the methacrylic resin composition C was confirmed. As a result, the structural units derived from each monomer of MMA, phMI, and chMI were 80.8% by mass, 7.1% by mass, and 12.1% by mass, respectively. Moreover, the weight average molecular weight Mw is 141,000, Mw/Mn is 2.31, Mz/Mw is 1.75, and the glass transition temperature is 134 degreeC.

[Manufacture Example 4] A reactor equipped with a temperature control device using a jacket and a stirring blade was charged with 40 parts by mass of MMA, 60 parts by mass of mXy, and 0.08 parts by mass of n-octanethiol as a chain transfer agent, and nitrogen gas was introduced. 1 hour to remove dissolved oxygen. Thereafter, steam was blown into the jacket to raise the temperature of the solution in the reactor to 120°C. While stirring at 50 rpm, 1,1-bis(tert-butylperoxidation) ring was added at a constant speed. A polymerization initiator solution prepared by dissolving 0.02 parts by mass of hexane in 0.10 parts by mass of mXy was polymerized for 5 hours, and then matured for 3 hours at 120°C. The polymerization was completed 8 hours after the start of the polymerization to obtain PMMA. mXy solution. After the polymerization is completed, the liquid temperature is lowered to 50°C. Secondly, a mixed solution containing 12 parts by mass of monomethylamine and 12 parts by mass of methanol was added dropwise into the reactor at room temperature, the liquid temperature was raised to 170°C, and stirred under pressure for 1 hour, thereby carrying out the pentalysis process. Cyclimine cyclization reaction. Lower the liquid temperature to 120°C, reduce the pressure in the reactor, and distill away unreacted monomethylamine and methanol, as well as part of mXy, to obtain approximately 50% mass mXy solution. To this polymerization solution were added 0.1 mass % of Irganox 1010 and 0.05 mass % of Irgafos 168 with respect to 100 mass % of the polymer contained in the solution. The polymerization solution containing the antioxidant was filtered by passing it through a filter containing metal fibers made of SUS316L and having a filtration accuracy of 2 μm. In order to recover the polymer from the polymerization solution, as a device for the devolatization step, a flat-plate heat exchanger with a flat-plate slit flow path and a heat medium flow path, and an attached SUS-made heat exchanger with an internal volume of about 0.3 ^m3 are used. A heat medium jacketed decompression vessel (hereinafter referred to as a devolatization tank) and a devolatization device without a rotating part. The solution containing the polymer obtained by polymerization was supplied to a heat exchanger installed on the upper part of the decompression vessel at a rate of 30 liters/hour, and after being heated to 260°C, the solution was maintained at an internal temperature of 260°C and a vacuum degree of 30 Torr. It is then supplied to a heated and depressurized devolatization tank to perform devolatization treatment. The shear rate in the devolatilization device was calculated based on the device shape and operating conditions, and the result was 5.3 s ^-1 . Use a gear pump to increase the pressure of the devolatized polymer from the lower part of the devolatilization tank, and extrude it from the strand die. After cooling with water, it is granulated to obtain methacrylic resin composition D. The composition of the obtained methacrylic resin composition D was confirmed. As a result, the acyl imidization rate was 3.2% and the amount of glutadiyl imine structural units was 5.1 mass %. Moreover, the weight average molecular weight Mw is 93,000, Mw/Mn is 1.79, Mz/Mw is 1.51, and the glass transition temperature is 122 degreeC.

[Manufacturing Example 5] Methacrylic resin composition E was obtained in the same manner as in Production Example 2 except that the amounts of each monomer in the solution prepared in the reactor were phMI 39.3 kg, chMI 46.5 kg, and MMA 354.2 kg. The composition of the methacrylic resin composition E was confirmed. As a result, the structural units derived from each monomer of MMA, phMI, and chMI were 83.2 mass%, 7.6 mass%, and 9.2 mass%, respectively. Moreover, the weight average molecular weight Mw is 143,000, Mw/Mn is 2.35, Mz/Mw is 1.81, and the glass transition temperature is 132 degreeC.

[Manufacturing Comparative Example 1] 352.4 kg of a 10.3 mass% mXy solution of phMI that has undergone the water washing step and the dehydration step (the mass of APSI relative to phMI is 0.42 mass ppm), and 20.3 mass% mXy of chMI that has gone through the water washing step and the dehydration step. 310.3 kg of the solution (the mass of CCSI relative to chMI is 0.60 ppm by mass) was added to a 1.25 m ³ reactor equipped with a temperature control device using a jacket and a stirring blade, while the solution temperature was 60°C and the pressure inside the reactor was maintained While stirring at 5 kPa, 335.4 kg of mXy was removed by distillation under reduced pressure. Then, the reaction kettle was returned to normal pressure, and mXy 8.9 kg was added to prepare a mixed solution of phMI 36.3 kg, chMI 63.0 kg, and mXy 236.9 kg. 340.7 kg of MMA and 0.275 kg of n-octanethiol as a chain transfer agent were measured, added and stirred to obtain a monomer mixed solution. Next, mXy 123.1 kg was measured and added to tank 1. Furthermore, 110.0 kg of MMA and 90.0 kg of mXy were measured in the tank 2 and stirred to prepare a monomer solution for addition. Nitrogen gas was introduced into the contents of the reactor at a rate of 30 L/min for 1 hour, and nitrogen gas was introduced into each of Tank 1 and Tank 2 at a rate of 10 L/min for 30 minutes to remove dissolved oxygen. Thereafter, steam was blown into the jacket to raise the temperature of the solution in the reactor to 128°C. While stirring at 50 rpm, 1,1-bis(tert-butyl) was added at a rate of 1 kg/hour. A polymerization initiator solution was prepared by dissolving 0.37 kg of cyclohexane (hydroxyperoxide) in 3.005 kg of mXy, thereby starting the polymerization. 0.5 hours after the start of polymerization, the addition rate of the starter solution was reduced to 0.25 kg/hour, and mXy was added from tank 1 at 35.2 kg/hour over 3.5 hours. Furthermore, during the polymerization, the solution temperature in the reactor was controlled to 128±2°C by temperature adjustment using a jacket. Then, 4 hours after the start of polymerization, the addition rate of the starter solution was changed to 0.75 kg/hour, and the monomer solution containing MMA was added from tank 2 at a rate of 100.0 kg/hour over 2 hours. Furthermore, 6 hours after the start of the polymerization, the addition rate of the starter solution was reduced to 0.5 kg/hour, and the addition was stopped 7 hours after the start of the polymerization. The polymerization was further continued for 1 hour, and a polymerization solution containing a methacrylic resin having a ring structural unit in the main chain was obtained. The amount of N-substituted maleimide contained in the obtained polymerization solution was evaluated and found to be 220 mass ppm of phMI and 1070 mass ppm of chMI. To this polymerization solution were added 0.1 mass % of Irganox 1010 and 0.05 mass % of Irgafos 168 with respect to 100 mass % of the polymer contained in the solution. The polymerization solution containing the antioxidant was filtered by passing it through a filter containing metal fibers made of SUS316L and having a filtration accuracy of 2 μm. Next, devolatilization is performed by introducing the obtained polymerization solution into a twin-screw extruder equipped with a plurality of exhaust ports for devolatization. The obtained polymerization solution was supplied to a twin-screw extruder at a rate of 10 kg/hour in terms of resin, and the conditions were set to a barrel temperature of 260°C, a screw speed of 150 rpm, and a vacuum degree of 10 to 40 Torr. The resin devolatized using a twin-screw extruder is extruded from a strand die, and then pelletized after cooling with water to obtain methacrylic resin composition F. The shear rate in the devolatilization device was calculated based on the device shape and operating conditions, and the result was 80 s ^-1 . The composition of the methacrylic resin composition F was confirmed. As a result, the structural units derived from each monomer of MMA, phMI, and chMI were 80.9% by mass, 7.0% by mass, and 12.1% by mass, respectively. Moreover, the weight average molecular weight Mw is 136,000, Mw/Mn is 2.35, Mz/Mw is 1.81, and the glass transition temperature is 134 degreeC.

[Production Comparative Example 2] A mixed solution of phMI 36.3 kg, chMI 63.0 kg, and mXy 236.9 kg was prepared in the same manner as in Production Example 2, except that commercially available products were used as phMI and chMI in an unrefined state. Acrylic resin composition G. The shear rate in the devolatilization device was calculated based on the device shape and operating conditions, and the result was 5.3 s ^-1 . Furthermore, the amount of N-substituted maleimide contained in the obtained polymerization solution was evaluated and found to be 220 mass ppm of phMI and 1070 mass ppm of chMI. The composition of the obtained granular polymer was confirmed. As a result, the structural units derived from each monomer of MMA, phMI, and chMI were 80.9% by mass, 7.1% by mass, and 12.1% by mass, respectively. Moreover, the weight average molecular weight Mw is 142,000, Mw/Mn is 2.32, Mz/Mw is 1.75, and the glass transition temperature is 134 degreeC.

[Manufacturing Comparative Example 3] As phMI and chMI, commercially available products were used in an unrefined state, and phMI 38.6 kg, chMI 65.7 kg, mXy 450.0 kg, MMA 445.7 kg, and n-octanethiol as a chain transfer agent 0.413 kg were measured. , put it into a 1.25 m ³ reactor equipped with a temperature regulating device using a jacket and a stirring blade, and stir to obtain a monomer mixed solution. To the content of the reactor, nitrogen gas was introduced at a rate of 30 L/min for 1 hour to remove dissolved oxygen. Thereafter, steam was blown into the jacket to raise the temperature of the solution in the reactor to 125°C. While stirring at 50 rpm, 1,1-bis(3-butyl) was added at a rate of 0.5 kg/hour. A polymerization initiator solution was prepared by dissolving 0.23 kg of cyclohexane (hydroxyperoxide) in 2.77 kg of mXy, thereby starting the polymerization. The addition was stopped 6 hours after the start of the polymerization. Furthermore, during the polymerization, the solution temperature in the reactor was controlled to 125±2°C by temperature adjustment using a jacket. After 8 hours passed from the start of polymerization, a polymerization solution containing a methacrylic resin having a ring structure in the main chain was obtained. The amount of N-substituted maleimide contained in the obtained polymerization solution was evaluated and found to be 1340 mass ppm of phMI and 4390 mass ppm of chMI. To this polymerization solution were added 0.1 mass % of Irganox 1010 and 0.05 mass % of Irgafos 168 with respect to 100 mass % of the polymer contained in the solution. The polymerization solution containing this antioxidant was filtered by passing it through a filter containing metal fibers made of SUS316L and having a filtration accuracy of 2 μm. The polymerization solution to which the antioxidant was added was supplied to a concentration device including a tubular heat exchanger and a vaporization tank preheated to 170° C., and the concentration of the polymer contained in the solution was increased to 70% by mass, and then The obtained polymerization solution was supplied to a thin film evaporator with a rotating section with a heat transfer area of 0.2 ^m2 , and was devolatized. At this time, the temperature in the device is 280°C, the supply volume is 30 L/hr, the rotation speed is 400 rpm, and the vacuum degree is 30 Torr. The gear pump is used to increase the pressure of the devolatized polymer, and it is extruded from the strand die and water-cooled. Then, it was pelletized, and methacrylic resin composition H was obtained. The shear rate in the thin film evaporator with a rotating part was calculated based on the device shape and operating conditions, and the result was 3200 s ^-1 . The composition of the obtained granular polymer was confirmed. As a result, the structural units derived from each monomer of MMA, phMI, and chMI were 81.0 mass%, 7.2 mass%, and 11.8 mass%, respectively. Moreover, the weight average molecular weight Mw was 136,000, Mw/Mn was 2.21, Mz/Mw was 1.71, and the glass transition temperature was 134 degreeC.

[Manufacturing Comparative Example 4] Methacrylic resin composition I was obtained in the same manner as in Production Example 2 except that the amounts of each monomer in the solution prepared in the reactor were phMI 41.3 kg, chMI 41.3 kg, and MMA 357.5 kg. The composition of the methacrylic resin composition I was confirmed. As a result, the structural units derived from each monomer of MMA, phMI, and chMI were 84.1% by mass, 8.0% by mass, and 7.9% by mass, respectively. Moreover, the weight average molecular weight Mw is 145,000, Mw/Mn is 2.31, Mz/Mw is 1.77, and the glass transition temperature is 130 degreeC.

[Manufacturing Comparative Example 5] Using a co-rotating twin-screw extruder, polymethyl methacrylate is imidized with monomethylamine to obtain methacrylic acid having a glutadiyl imine structural unit. System resin composition J. Specifically, a co-rotating twin-screw extruder with a screw diameter of 40 mm was used, the extruder cylinder temperature was set to 270°C, the screw speed was set to 150 rpm, and the weight average molecular weight was supplied from the hopper at 20 kg/h. Polymethyl methacrylate with Mw of 108,000, and nitrogen was allowed to flow into the extruder at a flow rate of 200 mL/min. After the resin is melted and filled in the kneading section, 1.8 parts by mass of monomethylamine relative to 100 parts by mass of the raw material resin is injected from the nozzle to perform the imidization reaction. Place a reverse thread at the end of the reaction zone (near the exhaust port) to fill it with resin. Reduce the pressure at the exhaust port to 50 Torr to remove the reaction by-products and excess methylamine. The resin discharged as a strand from the die nozzle provided at the outlet of the extruder is cooled in a water tank and then granulated using a granulator to obtain an imine resin. Then, a co-rotating twin-screw extruder with a screw diameter of 40 mm was used, the extruder cylinder temperature was set to 250°C, the screw speed was set to 150 rpm, and the obtained imine resin was supplied at 20 kg/hr. , after the resin is melted and filled through the kneading section, a mixture of dimethyl carbonate and triethylamine as the esterification agent is injected from the nozzle to reduce the carboxylic acid groups in the resin. The dimethyl carbonate system was set to 3.2 parts by mass, and the triethylamine system was set to 0.8 parts by mass relative to 100 parts by mass of the imine resin. Place a reverse thread at the end of the reaction zone to fill it with resin. Reduce the pressure at the exhaust port to 50 Torr to remove the reaction by-products and excess dimethyl carbonate. The resin discharged as a strand from the die nozzle provided at the outlet of the extruder was cooled in a water tank and then granulated using a granulator to obtain a methacrylic resin composition J having a glutadirylimine structure. The resin composition has an imidization rate of 3.3% and a content of glutadiimide structural units of 5.2 mass%. The shear rate in the twin-screw extruder was calculated based on the device shape and operating conditions, and the result was approximately 80 s ^-1 . Moreover, the weight average molecular weight Mw is 96,000, Mw/Mn is 1.82, Mz/Mw is 1.48, and the glass transition temperature is 122 degreeC.

[Examples 1 to 5, Comparative Examples 1 to 5] Using the methacrylic resin compositions A to J obtained in the Production Examples and the Production Comparative Examples, a resin lens was injection molded by the following method, and each characteristic was measured. The results are shown in Table 1. ＜Forming of resin lens＞ After drying the methacrylic resin compositions A to J at 100°C for 4 hours using a forced air circulation dryer, a spherical plano-convex lens with a diameter of 41 mm and an R98 mm (the thickest part is 3.2 mm and has a side gate) is used. (thickness 0.95 mm, width 5.0 mm)), using an injection molding machine with a clamping force of 50 T, under the conditions of cylinder temperature 270°C, mold temperature 116°C, and injection speed 10 mm/s, by holding the pressure for two The first section is maintained at a pressure of 50 MPa for 4 seconds, then the second section is maintained at a pressure of 30 MPa for 3 seconds, and injection molding is performed with a cooling time of 400 seconds. Furthermore, annealing was performed for 3 hours in an oven set to a temperature 25° C. lower than the glass transition temperature of the methacrylic resin composition.

[Table 1] Example 1 Example 2 Example 3 Example 4 Example 5 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 Comparative example 5 Methacrylic resin composition used Methacrylic resin composition A Methacrylic resin composition B Methacrylic resin composition C Methacrylic resin composition D Methacrylic resin composition E Methacrylic resin composition F Methacrylic resin composition G Methacrylic resin composition H Methacrylic resin composition I Methacrylic resin composition J Manufacturing method of methacrylic resin Amount of 2-amino-N-substituted succinimine APSI Quality ppm 0.42 0.42 3.4 - 0.42 0.42 60 60 0.42 - CCSI Quality ppm 0.60 0.60 4.6 - 0.60 0.60 80 80 0.60 - Amount of unreacted maleimide at the end of polymerization phMI Quality ppm 1340 220 210 - 230 220 220 1340 250 - mi Quality ppm 4390 1070 1090 - 810 1070 1070 4390 740 - to evaporate method - Flash to evaporate Flash to evaporate Flash to evaporate Flash to evaporate Flash to evaporate Twin shaft extrusion Flash to evaporate thin film evaporation Flash to evaporate Twin shaft extrusion temperature ℃ 260 260 260 260 260 260 260 260 260 270 Characteristics of resin lenses Phase difference within the effective diameter (average of absolute values) Before annealing nm 2.8 2.4 2.5 6.8 5.7 2.7 2.5 2.6 6.6 6.5 After annealing nm 1.7 1.5 1.5 2.8 4.6 1.6 1.5 1.6 5.2 2.9 Content of fluorescent luminescent substances mol/L 3.2× ^10-9 1.5× ^10-9 1.9×10 ^{-9 2.2} × ^10-9 1.3× ^10-9 5.1× ^{10-9 4.5} × ^10-9 18.0× ^10-9 1.4 ^{× 10-9} 5.3× ^10-9 Glass transition temperature (Tg) ℃ 133 134 134 122 132 134 134 134 130 122 Photoelastic coefficient (C _R ) Pa ^{-1 -0.1} × ^10-12 -0.2 ^{× 10-12} -0.2 ^{× 10-12 -3.0} × ^10-12 -0.2 ^{× 10-12} -0.2 ^{× 10-12} -0.2 ^{× 10-12} -0.1 ^{× 10-12 -0.1} × ^{10-12 -3.0} × ^10-12 Light transmittance (T450 nm/T680 nm) - 0.98 0.99 0.99 0.98 0.99 0.95 0.95 0.93 0.99 0.95 Features of HMD image clarity - 〇 〇 〇 〇 〇 △ △ × × × [Industrial availability]

The resin lens for a head-mounted display of the present invention can obtain clear images even if it is an optical system using polarized light. Therefore, it can contribute to making the head-mounted display smaller and lighter.

1:LCD display 2:Polarizing plate 3:1/4 wavelength plate 4: Half mirror 5:Resin lens 6:1/4 wavelength plate 7: Reflective polarizing plate

FIG. 1 is a diagram schematically showing a simulation device that reproduces the principle of a head-mounted display described in Japanese Patent Application Laid-Open No. 2017-21321. In the embodiment, the simulation device is used to evaluate the clarity of the image.

1:LCD display

2:Polarizing plate

3:1/4 wavelength plate

4: Half mirror

5:Resin lens

6:1/4 wavelength plate

7: Reflective polarizing plate

Claims (9)

A resin lens for a head-mounted display, characterized in that the average absolute value of the phase difference within the effective diameter is 5 nm or less, when measured at an excitation wavelength of 436 nm with respect to a 2.0% by mass solution obtained by dissolving it in chloroform. The fluorescence intensity at a wavelength of 530 nm and the content of the fluorescent substance calculated using the concentration-intensity conversion formula of the luciferin ethanol solution is 0.1~4.0×10 ^-9 mol/L. For example, the resin lens for a head-mounted display according to claim 1 has a glass transition temperature (Tg) of more than 120°C and less than 160°C. For example, in claim 1, the resin lens for a head-mounted display has an absolute value of photoelastic coefficient of 3.0×10 ^-12 Pa ^-1 or less. For example, in claim 2, the resin lens for a head-mounted display has an absolute value of photoelastic coefficient of 3.0×10 ^-12 Pa ^-1 or less. The resin lens for a head-mounted display according to any one of claims 1 to 4, which contains a methacrylic resin. A resin lens for a head-mounted display according to claim 5, wherein the methacrylic resin includes a methacrylic resin having a structural unit (X), and the structural unit (X) has a ring structure in the main chain. The resin lens for a head-mounted display according to claim 6, wherein the above-mentioned structural unit (X) includes a structural unit selected from the group consisting of N-substituted maleimide monomers, glutadiylimine-based structural units, and At least one structural unit among the group consisting of lactone ring structural units. A resin lens for a head-mounted display according to claim 6, wherein the structural unit (X) includes a structural unit derived from an N-substituted maleimide monomer. A resin lens for a head-mounted display according to claim 6, wherein the structural unit (X) includes a glutadiimide structural unit.