JP7093246B2 - Acrylic resin lens - Google Patents

Description

The present invention relates to a methacrylic resin lens. More specifically, the present invention relates to a methacrylic resin lens having high heat resistance, high light transmittance, and little change in color.

As the LED for lighting, an LED package made of an LED chip and a transparent resin that seals the LED chip is usually used. As the LED package, a cannonball type (lead frame type), a surface mount type, a COB, and the like are known. Lenses are used to distribute, focus, or diffuse the light emitted by the LED package. Since the emission spectrum of the LED chip is concentrated in a narrow range near a specific wavelength and emits almost no infrared rays, the lens is not heated by radiant heat. However, since the luminous flux per LED chip is smaller than that of a light bulb or a fluorescent lamp, it is necessary to use a plurality of LED chips. Since a lighting LED having a plurality of LED chips generates a considerable amount of heat, the lens may be heated by the conduction heat. In the lighting LED, a methacrylic resin lens, a polycarbonate resin lens, or the like is used from the viewpoint of weight reduction and the like. Compared with polycarbonate resin, methacrylic resin has high light transmittance and excellent weather resistance. However, it is said that the methacrylic resin is more likely to be deformed by heat, colored by heat, and colored by ultraviolet rays than the polycarbonate resin.

Various proposals have been made to improve the heat resistance of the methacrylic resin.
For example, Patent Document 1 describes a methacrylic resin [1] having a triad syndiotacticity (rr) of 65% or more and a methacrylic resin [2] having a triad syndiotacticity (rr) of 45 to 58%. , A methacrylic resin composition contained in a methacrylic resin [1] / methacrylic resin [2] in a mass ratio of 40/60 to 70/30 is disclosed. It discloses that the resin composition can be molded and used for a Fresnel lens and a lenticular lens.

Patent Document 2 contains methyl methacrylate and an acrylic acid ester, and the content ratio of the methyl methacrylate is 95.5% by weight or more, and the content ratio of the acrylic acid ester is 4.5% by weight or less. It contains a copolymer obtained by polymerizing a polymer component, has a reduced viscosity at 25 ° C. measured as a chloroform solution having a concentration of 0.5 g / 50 ml, and has a reduced viscosity of 40 to 50 ml / g. Disclosed are methacrylic resin compositions having a viscosity of 47-51%. It is disclosed that this resin composition can provide a lens having a good appearance by injection molding.

Patent Document 3 describes a methacrylic resin [I] having a triad syndiotacticity (rr) of 65% or more and a methacrylic resin [II] having a triad syndiotacticity (rr) of 45 to 58%. Gel permeation with a total content of structural units derived from methyl methacrylate of 90% by mass or more, including melt-kneading at a molecular weight ratio of resin [I] / methacrylic resin [II] of 40/60 to 70/30. The molecular weight _MA in terms of polystyrene corresponding to the retention time showing the maximum intensity value in the chromatogram obtained by chromatography is 30,000 or more and 100,000 or less, and the intensity is 70% or more with respect to the maximum intensity value in the chromatogram. The area S _gA of the region surrounded by the approximate curve fitted to the Gaussian function by the non-linear least square method using only the data in the range shown and the baseline of the chromatogram is the chromatogram and its baseline. Ratio of weight average molecular weight Mw _gA to number average molecular weight Mn _gA , which is 45 to 80% of the area _SA of the enclosed area and is calculated based on the approximation curve obtained by the fitting, Mw _gA / A method for producing a methacrylic resin having a Mn _gA of 1.01 or more and 1.20 or less is disclosed.

Patent Document 4 describes a methacrylic resin (A) having a triad syndiotacticity (rr) of 58% or more and a content of structural units derived from methyl methacrylate of 90% by mass or more, and a methacrylic acid ester weight. A block copolymer (B) containing 10 to 80% by mass of the combined block (b1) and 90 to 20% by mass of the acrylic acid ester polymer block (b2), and a block copolymer with respect to the methacrylic resin (A) ( B) discloses a methacrylic resin composition having a mass ratio of 1/99 to 90/10.

WO 2014/185509 A WO 2015/037691 A WO 2016/002750 A WO 2015/182750 A

Composites Science and Technology 2010, 70, 2045-2055

An object of the present invention is to provide a methacrylic resin lens having high heat resistance, high light transmittance, and little change in color.

As a result of studies for solving the above problems, the present invention including the following forms has been completed.

[1] 100 parts by mass of methacrylic resin, 5 × 10 ^-6 to 4 × 10 ^-3 parts by mass of a metal element having an atomic number of 20 or less, and 0.025 to 0.50 parts by mass of a hindered phenolic antioxidant. Contains,
The amount of terminal double bond is less than 0.012 mol% with respect to the methacrylic resin.
The triad syndiotacticity (rr) is 50% to 65%, and the thermogravimetric retention rate when exposed to 290 ° C. for 15 minutes in a nitrogen gas atmosphere is 98% by mass or more.
lens.

[2] When the glass transition temperature is 123 ° C to 130 ° C,
When the amount of residual methyl methacrylate is 1.0% by mass or less and the optical path length is converted to 3 mm, the light transmittance at 450 nm is such that the ultraviolet rays have a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW /. At cm ² , it is 91% or more both before and after 1000 hours of irradiation.
The lens according to [1].

[3] The lens according to [1] or [2], wherein the amount of bonded sulfur atoms is less than 0.25 mol% with respect to the methacrylic resin.
[4] The lens according to any one of [1] to [3], wherein the weight average molecular weight Mw is 50,000 to 150,000.
[5] The lens according to any one of [1] to [4], wherein the content of the structural unit derived from methyl methacrylate is 99% by mass or more with respect to the methacrylic resin.
[6] The lens according to any one of [1] to [5], which further contains an ultraviolet absorber.

The lens of the present invention has high heat resistance, high light transmittance, and little change in color. The lens of the present invention is less likely to cause strength deterioration due to heat, coloring due to heat, dimensional variation due to heat, coloring due to ultraviolet rays, dimensional variation due to ultraviolet rays, bleed-out of additives, and the like. Since the lens of the present invention has excellent weather resistance, it can be used both indoors and outdoors. The lens of the present invention can also be used for, for example, road lighting equipment, vehicle lighting equipment, and the like.

It is a figure which shows an example of the lens of this invention.

The lens of the present invention comprises a methacrylic resin, a metal element having an atomic number of 20 or less, and a hindered phenolic antioxidant.

The methacrylic resin contained in the lens of the present invention has a terminal double bond amount of preferably less than 0.012 mol%, more preferably less than 0.011 mol%.

The amount of the terminal double bond of the methacrylic resin is a value D _p determined as follows.
A solution is obtained by dissolving the methacrylic resin in deuterated chloroform so as to have a concentration of 15 to 20% by mass. 10% by mass of tris (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedinate) europium with respect to the mass of the methacrylic resin was added to the solution. Added. The solution is integrated and measured by ¹ H-NMR for 12 hours or more. From the obtained ¹ H-NMR spectrum, the total integral intensity _Xp of the signals (resonance frequencies 5.5 ppm and 6.2 ppm) derived from the terminal double bond and the signal derived from the methoxy group of the methyl methacrylate main chain. The integrated intensity Y _p at (resonance frequency 3.6 ppm) is measured, and the amount D _p of the terminal double bond is calculated by the following equation.
D _p = [(X _p / 2) / (Y _p / 3)] × 100

The methacrylic resin contained in the lens of the present invention has a bound sulfur atom content of preferably less than 0.25 mol%, more preferably less than 0.15 mol%.

The amount of the bonded sulfur atom of the methacrylic resin is a value _Sp determined as follows.
The methacrylic resin is dissolved in chloroform to obtain a solution. This solution is added to n-hexane to give a precipitate. The precipitate is dried at 80 ° C. for at least 12 hours under vacuum. An appropriate amount of the obtained dried product is precisely weighed, set in a sulfur combustion device, decomposed in a reaction furnace at a temperature of 400 ° C., and the generated gas is passed through a furnace at a temperature of 900 ° C., and then a 0.3% hydrogen peroxide solution is used. Absorb with. The obtained liquid (decomposed gas aqueous solution) is appropriately diluted with pure water, and sulfate ions are quantified by ion chromatography (ICS-1500 manufactured by DIONEX, column: AS12A). Calculate the mass W _p (mass%) of sulfur atoms per mass of the dried product. Next, the amount S _p (mol%) of the bonded sulfur atom is calculated by the following formula.
Sp _{= W p ×} (100/32)

The methacrylic resin contained in the lens of the present invention has a lower limit of triad syndiotacticity (rr) of preferably 50%, more preferably 52%, still more preferably 53%, still more preferably 54%, and the triad. The upper limit of the syndiotacticity (rr) is preferably 65%, more preferably 64%, still more preferably 63%, even more preferably 62%, and most preferably 61%.

In general, methacrylic resins have structural isomerism due to the conformation of asymmetric carbons on the molecular chain. Specifically, a structure with the same configuration (isotactic diad structure or meso structure [m]) in a doublet (diad) and a structure with a different configuration (syngiotac) in a doublet (diad). Tick dyad structure or racemo structure [r]), structure in which isotactic dyad structures are lined up in triplets (triads) (isotactic triad structure, [m, m]), synji in triplets (triads) A structure in which tactical diad structures are lined up (syndiotactic triad structure, [r, r]), a structure in which an isotactic diad structure and a syndiotactic diad structure are lined up in a triplet (triad) (heterotactic triad structure) , [M, r] or [r, m]) and the like.

The triad syndiotacticity (rr) is the ratio of the syndiotactic triad structure to the total triad structure. For the triad syndiotacticity (rr) (%) of the methacrylic resin, the methacrylic resin was dissolved in deuterated chloroform, and a ¹ H-NMR spectrum was measured at 30 ° C. for the solution, and the TMS was set to 0 ppm from the spectrum. The area (X) in the region of 0.6 to 0.95 ppm and the area (Y) in the region of 0.6 to 1.35 ppm are measured and calculated by the formula: (X / Y) × 100. Can be done.

The methacrylic resin contained in the lens of the present invention has a lower limit of the glass transition temperature of preferably 100 ° C, more preferably 110 ° C, still more preferably 120 ° C, particularly preferably 122 ° C, and an upper limit of the glass transition temperature. , Preferably 131 ° C. The glass transition temperature of the methacrylic resin is an intermediate point glass transition temperature (Tmg) determined based on the measurement data by differential scanning calorimetry (DSC) in accordance with JIS K7121.

The methacrylic resin contained in the lens of the present invention has a weight average molecular weight Mw of preferably 50,000 to 150,000, more preferably 50,000 to 120,000, and even more preferably 50,000 to 100,000. When the weight average molecular weight Mw of the methacrylic resin is in the above range, the balance between impact resistance, toughness and moldability tends to be good. The Mw of the methacrylic resin (A) is a value obtained by converting a chromatogram measured by gel permeation chromatography (GPC) into a molecular weight of standard polystyrene.

The methacrylic resin contained in the lens of the present invention has a structural unit derived from methyl methacrylate, preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, and further. It is preferably 99% by mass or more, and most preferably 100% by mass.

The methacrylic resin may randomly contain structural units derived from a monomer other than methyl methacrylate in the molecular chain. Examples of the monomer other than methyl methacrylate include an alkyl methacrylate ester other than methyl methacrylate such as ethyl methacrylate and butyl methacrylate; an aryl methacrylate ester such as phenyl methacrylate; cyclohexyl methacrylate and methacrylic acid. Methacrylic acid cycloalkyl ester such as norbornenyl; acrylic acid alkyl ester such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate; acrylic acid aryl ester such as phenyl acrylate; acrylic Acrylic acid cycloalkyl esters such as cyclohexyl acid and norbornenyl acrylate; aromatic vinyl compounds such as styrene and α-methylstyrene; acrylamide; methacrylicamide; acrylonitrile; methacrylic nitrile; etc. -A vinyl-based monomer having only one carbon double bond can be mentioned.

The method for producing the methacrylic resin is not particularly limited, but the anionic solution polymerization method is preferable from the viewpoint of reducing the amount of bound sulfur atoms and having good heat resistance and heat decomposition resistance.

Methyl (meth) acrylate and other monomers used in the production of methacrylic resin should be sufficiently dried in advance in an atmosphere of an inert gas such as nitrogen, argon or helium to facilitate the polymerization reaction. It is preferable from the viewpoint of advancing to. In the drying treatment, a dehydrating agent or a desiccant such as calcium hydride, molecular sieves, or activated alumina is preferably used.

The solvent used in the anionic solution polymerization method is not particularly limited as long as it does not adversely affect the reaction, and is, for example, an aliphatic hydrocarbon such as pentane, n-hexane, or octane; cyclopentane, methylcyclopentane, cyclohexane, or methyl. Alicyclic hydrocarbons such as cyclohexane and ethylcyclohexane; aromatic hydrocarbons such as benzene, toluene, ethylbenzene and xylene; ethers such as diethyl ether, tetrahydrofuran, 1,4-dioxane, anisole and diphenyl ether. .. These solvents may be used alone or in combination of two or more. Of these, aromatic hydrocarbons are preferable, and toluene and xylene are particularly preferable. The solvent is preferably purified by degassing, dehydration or the like before use.

The anion solution polymerization method uses, for example, an organic alkali metal compound or an organic alkaline earth metal compound and an alkali metal salt or an alkaline earth metal salt (see Japanese Patent Publication No. 7-25859), and the organic alkali metal compound and the organic aluminum. It can be carried out using a compound (see JP-A-11-335432) and using an organic rare earth metal complex (see JP-A-6-93060).

Examples of the organic alkali metal compound or the organic alkaline earth metal compound which is an anion polymerization initiator include an organic lithium compound, an organic sodium compound, an organic potassium compound, and an organic magnesium compound. These can be used alone or in combination of two or more. Of these, organolithium compounds are preferred.

Examples of the organic lithium compound include methyl lithium, ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, s-butyl lithium, isobutyl lithium, t-butyl lithium, n-pentyl lithium, and n-hexyl lithium. Alkyllithium and alkyldilithium such as tetramethylenedilithium, pentamethylenedilithium, hexamethylenedilithium; aryllithium and aryldilithium such as phenyllithium, m-tolyllithium, p-tolyllithim, xylyllithium, lithium naphthalene; Aralkyllithium and aralkyldilithium such as benzyllithium, diphenylmethyllithium, trityllithium, 1,1-diphenyl-3-methylpentyllithium, α-methylstyryllithium, dilithium produced by the reaction of diisopropenylbenzene with butyllithium; Lithium amides such as lithium dimethylamide, lithium diethylamide, lithium diisopropylamide; lithium methoxyd, lithium ethoxydo, lithium n-propoxide, lithium isopropoxide, lithium n-butoxide, lithium s-butoxide, lithium t-butoxide, lithium Lithium alkoxides such as pentyl oxide, lithium hexyl oxide, lithium heptyl oxide, lithium octyl oxide; lithium phenoxide, lithium 4-methylphenoxide, lithium benzyl oxide, lithium 4-methylbenzyl oxide and the like. Of these, n-butyllithium, s-butyllithium, t-butyllithium, diphenylmethyllithium, 1,1-diphenyl-3-methylpentyllithium, and α-methylstyryllithium are particularly preferable.

The amount of the organic alkali metal compound or the organic alkaline earth metal compound used is not particularly limited, but the concentration in the polymerization reaction solution is preferably 0.1 to 100 mmol / l, more preferably 1 to 10 mmol / l.

A compound having an anionizable moiety may be anionized with an organic alkali metal compound or an organic alkaline earth metal compound, and the compound may be used as an anionic polymerization initiator. Examples of the compound having an anionizable moiety include a linear or cyclic conjugated diene compound, a vinyl aromatic compound, and a (meth) acrylic acid amide.

Any polymer having an anionicizable moiety may be anionicized with an organic alkali metal compound or an organic alkaline earth metal compound and used as an anionic polymerization initiator (sometimes referred to as a living polymer). .. For example, poly (p-methylstyrene) dissolved in cyclohexane under an inert gas atmosphere is reacted with s-butyllithium in the presence of N, N, N', N'-tetramethylethylenediamine to give a paraposition. Poly (p-methylstyrene) in which the methyl group of the above is anionized by an appropriate amount can be obtained. Examples of the site that can be anionized include a unit derived from a linear or cyclic conjugated diene compound, a unit derived from a vinyl aromatic compound, a unit derived from a (meth) acrylic acid amide, and the like. A graft polymer can be obtained by using the living polymer as an anionic polymerization initiator.

In the anionic solution polymerization method, it is preferable to use the organoalkali metal compound and the organoaluminum compound in combination.
As the organoaluminum compound, a compound represented by the formula (I) (hereinafter referred to as Al compound (I)) is preferably used.
AlR ³ R ⁴ R ⁵ (I)
In formula (I), R ³ , R ⁴ and R ⁵ each independently have an alkyl group which may have a substituent, a cycloalkyl group which may have a substituent, and a substituent. It represents a good aryl group, an aralkyl group which may have a substituent, an alkoxyl group which may have a substituent, an aryloxy group which may have a substituent or an N, N-disubstituted amino group. R ⁴ and R ⁵ may be allierangeoxy groups that may have substituents together.
The Al compound (I) is preferably an aryloxy group in which at least one of R ³ , R ⁴ and R ⁵ may have a substituent, and two of R ³ , R ⁴ and R ⁵ are substituted. More preferably, it is an aryloxy group which may have a group.
Examples of the aryloxy group which may have a substituent include a phenoxy group, a 2-methylphenoxy group, a 4-methylphenoxy group, a 2,6-dimethylphenoxy group and a 2,4-di-t-butylphenoxy group. , 2,6-di-t-butylphenoxy group, 2,6-di-t-butyl-4-methylphenoxy group, 2,6-di-t-butyl-4-ethylphenoxy group, 2,6-diphenyl Examples thereof include a phenoxy group and a 7-methoxy-2-naphthoxy group. Further, R ² and R ³ may be combined to form an Allie Rangeoxy group.

Specific examples of the Al compound (I) include diethyl (2,6-di-t-butyl-4-methylphenoxy) aluminum, diethyl (2,6-di-t-butylphenoxy) aluminum, and diisobutyl (2,6). -Di-t-butyl-4-methylphenoxy) aluminum, diisobutyl (2,6-di-t-butylphenoxy) aluminum, din-octyl (2,6-di-t-butyl-4-methylphenoxy) aluminum , Di-n-octyl (2,6-di-t-butylphenoxy) aluminum, ethylbis (2,6-di-t-butyl-4-methylphenoxy) aluminum, ethylbis (2,6-di-t-butylphenoxy) ) Aluminum, ethyl [2,2'-methylenebis (4-methyl-6-t-butylphenoxy)] Aluminum, isobutylbis (2,6-di-t-butyl-4-methylphenoxy) aluminum, isobutylbis (2) , 6-di-t-butylphenoxy) Aluminum, Isobutyl [2,2'-methylenebis (4-methyl-6-t-butylphenoxy)] Aluminum, n-octylbis (2,6-di-t-butyl-4) -Methylphenoxy) Aluminum, n-octylbis (2,6-di-t-butylphenoxy) aluminum, n-octyl [2,2'-methylenebis (4-methyl-6-t-butylphenoxy)] aluminum, methoxybis (2,6-di-t-butyl-4-methylphenoxy) Aluminum, methoxybis (2,6-di-t-butylphenoxy) Aluminum, methoxy [2,2'-methylenebis (4-methyl-6-t-) Butylphenoxy)] Aluminum, ethoxybis (2,6-di-t-butyl-4-methylphenoxy) aluminum, ethoxybis (2,6-di-t-butylphenoxy) aluminum, ethoxy [2,2'-methylenebis (4) -Methyl-6-t-butylphenoxy)] Aluminum, isopropoxybis (2,6-di-t-butyl-4-methylphenoxy) aluminum, isopropoxybis (2,6-di-t-butylphenoxy) aluminum , Isopropoxy [2,2'-methylenebis (4-methyl-6-t-butylphenoxy)] aluminum, t-butoxybis (2,6-di-t-butyl-4-methylphenoxy) aluminum, t-butoxybis ( 2,6-di-t-butylphenoxy) aluminum, t-butoxy [2,2'-methylenebis (4) -Methyl-6-t-butylphenoxy)] Aluminum, Tris (2,6-di-t-butyl-4-methylphenoxy) aluminum, Tris (2,6-diphenylphenoxy) aluminum and the like can be mentioned. These may be used alone or in combination of two or more.
The amount (mol) of Al compound (I) used is not particularly limited. The amount of Al compound (I) used (mol) is larger than the amount of organic alkali metal compound used (mol), and the amount of Al compound (I) used (mol) and the amount of organic alkali metal compound used (mol) The molar ratio of the total amount (molar) of methyl methacrylate and other monomers used to the difference is preferably set to 15 to 80, more preferably 15 to 70, and even more preferably 20 to 50. Is preferable.

The anionic solution polymerization method is preferably carried out in an atmosphere of an inert gas such as nitrogen, argon or helium.

In the anionic solution polymerization method, a polymerization regulator can be added as needed.
Examples of the polymerization regulator include ethers such as dimethyl ether, dimethoxyethane, diethoxy ethane, and 12-crown-4; triethylamine, N, N, N', N'-tetramethylethylenediamine, N, N, N', N. Organic nitrogen-containing compounds such as ", N" -pentamethyldiethylenetriamine, 1,1,4,7,10,10-hexamethyltriethylenetetramine, pyridine, 2,2'-dipyridyl; triethylphosphine, triphenylphosphine, 1 , 2-Bis (diphenylphosphino) organic phosphorus compounds such as ethane; inorganic salts such as lithium chloride, sodium chloride, potassium chloride; alkali metal alkoxides such as lithium (2-methoxyethoxy) ethoxydo, potassium t-butoxide; tetraethylammonium Examples thereof include quaternary ammonium salts such as chloride, tetraethylammonium bromide, tetraethylphosphonium chloride and tetraethylphosphonium bromide, and quaternary phosphonium salts. These polymerization modifiers may be used alone or in combination of two or more. Among these, ether and organic nitrogen-containing compounds are preferable. The amount of the polymerization modifier used is not particularly limited, but the concentration in the polymerization reaction solution is preferably 0.1 to 100 mmol / l, more preferably 1 to 10 mmol / l.

The anionic polymerization reaction is preferably terminated by the addition of a polymerization terminator. Examples of the polymerization terminator include compounds having active hydrogen such as water, methanol, acetic acid, and hydrochloric acid. The polymerization terminator can be used alone or in combination of two or more. The polymerization inhibitor may be used in the state of an aqueous solution or an organic solvent solution. The amount of the polymerization terminator used is preferably in the range of 1 to 100 mol with respect to the total amount of 1 mol of the anion polymerization initiator and the organoaluminum compound used, and the amount of the terminal double bond is within a predetermined range. It is preferable to set so as to be.

The metal elements having an atomic number of 20 or less contained in the lens of the present invention are Li, Be, Na, Mg, Al, K, and Ca. Of these, Li and Al are preferable. The metal element having an atomic number of 20 or less may be derived from an organometallic compound used in the production of a methacrylic resin or an organometallic compound that may be added when molding into a lens. As the organometallic compound, an organolithium compound and an organoaluminum compound are particularly preferable.
The lower limit of the amount of the metal element having an atomic number of 20 or less contained in the lens of the present invention is 5 × 10 ^-6 parts by mass (concentration 0.05 ppm), preferably 1 × 10 with respect to 100 parts by mass of the methacrylic resin. ^-5 parts by mass (concentration 0.1 ppm), more preferably 1 × 10 ^-4 parts by mass (concentration 1 ppm), still more preferably 2 × 10 ^-4 parts by mass (concentration 2 ppm), still more preferably 4 × 10 ^-4 . It is by mass (concentration 4 ppm), and the upper limit is 4 × 10 ^-3 parts by mass (concentration 40 ppm), preferably 35 × 10 ^-3 parts by mass (concentration 35 ppm), more preferably with respect to 100 parts by mass of methacrylic resin. It is 3 × 10 ^-3 parts by mass (concentration 30 ppm), more preferably 2 × 10 ^-3 parts by mass (concentration 20 ppm).
The amount of the Al element contained in the lens of the present invention is preferably 1 × 10 ^-5 to 3.9 × 10 ^-3 parts by mass, more preferably 1.9 × 10 ⁻ with respect to 100 parts by mass of the methacrylic resin. ⁴ to 3 × 10 ^-3 parts by mass, more preferably 3.5 × 10 ^-4 to 2.5 × 10 ^-3 parts by mass. The amount of the Li element contained in the lens of the present invention is preferably 1 × 10 ^-6 to 1 × 10 ^-3 parts by mass, and more preferably 5 × 10 ^-6 to 5 × with respect to 100 parts by mass of the methacrylic resin. It is 10 ^-4 parts by mass, more preferably 2 × 10 ^-5 to 1 × 10 ^-4 parts by mass.
The amount of the metal element having an atomic number of 20 or less contained in the lens of the present invention is the amount of the metal element having an atomic number of 20 or less originally contained in the methacrylic resin and the amount of the metal element having an atomic number of 20 or less added to the lens. It is the total amount with the amount of metal elements. A metal element having an atomic number of 20 or less improves the transparency and heat-decomposability of a lens by a synergistic effect with a small amount of a hindered phenolic antioxidant.
The content of the metal element having an atomic number of 20 or less is a value determined as follows.
Add 0.15 g of lens to 10 ml of sulfuric acid and irradiate with microwave at 220 ° C. for 25 minutes. After allowing to cool, the lens is removed, and ion-exchanged water is added to the remaining solution to obtain 20 ml of solution. This solution is calculated by quantitative analysis by ICP emission spectroscopy.
The content of the metal element having an atomic number of 20 or less is the type and amount of the monomer, organic metal compound, polymerization inhibitor, etc. used in the production of the methacrylic resin, and the degree of purification performed after the production of the methacrylic resin. Can be adjusted by. The degree of purification is not particularly limited as long as the content of the metal element having an atomic number of 20 or less determined by the quantitative analysis is within the above range.

The hindered phenolic antioxidant contained in the lens of the present invention is a substance having a phenolic hydroxyl group that receives a radical generated by a reaction with oxygen and changes into a stable phenoxy radical, and is an antioxidant of a thermoplastic resin. It has been used for a long time.

As hindered phenolic antioxidants, 2,6-bis (1,1-dimethylethyl) -4-methylphenol (manufactured by Wako Pure Chemical Industries, Ltd .; BHT), 3,5-di-tert-butyl-4- Hydroxytoluene, pentaerythrityl-tetrakis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] (manufactured by BASF; trade name IRGANOX1010), octadecyl-3- (3,5-di-) Phenol (tert-butyl-4-hydroxyphenyl) propionate (manufactured by BASF; trade name IRGANOX1076) and the like are preferable. A hindered phenolic antioxidant having a molecular weight of 300 or less is particularly preferable because it has high sublimation properties and reduces roll stains due to bleed-out.
The amount of the hindered phenolic antioxidant contained in the lens of the present invention is 0.025 to 0.50 parts by mass, preferably 0.028 to 0.18 parts by mass, based on 100 parts by mass of the methacrylic resin. More preferably, it is 0.03 to 0.15 parts by mass. When the amount of the hindered phenolic antioxidant is within the above range, the balance between the effect of suppressing deterioration of the lens appearance due to bleed-out or the like and the effect of improving the heat-resistant decomposition property is good.

The lens of the present invention may contain an antioxidant other than the hindered phenolic antioxidant. Examples of the antioxidant other than the hindered phenolic antioxidant include phosphorus-based antioxidants and thioether-based antioxidants.
From the viewpoint of the effect of preventing deterioration of optical properties due to coloring, it is more preferable to use a phosphorus-based antioxidant and a hindered phenol-based antioxidant in combination.
When a phosphorus-based antioxidant and a hindered phenol-based antioxidant are used in combination, the amount of the phosphorus-based antioxidant used: the amount of the hindered phenol-based antioxidant used is 1: 5 to 2: by mass ratio. 1 is preferable, and 1: 2 to 1: 1 is more preferable.

Phosphorus-based antioxidants include 2,2-methylenebis (4,6-dit-butylphenyl) octylphosphite (manufactured by ADEKA; trade name: ADEKA STAB HP-10), tris (2,4-dit-). Butylphenyl) phosphite (manufactured by BASF; trade name: IRGAFOS168) and the like are preferable.

The lens of the present invention is a heat deterioration inhibitor, a light stabilizer, an ultraviolet absorber, a lubricant, a mold release agent, a polymer processing aid, an antistatic agent, a flame retardant, and a dye pigment as long as the effects of the present invention are not impaired. , Light diffusing agents, organic dyes, matting agents, impact resistance modifiers, other additives such as phosphors, or polymers other than methacrylic resins.

An ultraviolet absorber is a compound having an ability to absorb ultraviolet rays. The ultraviolet absorber is a compound that is said to have a function of mainly converting light energy into heat energy.
Examples of the ultraviolet absorber include benzophenones, benzotriazoles, triazines, benzoates, salicylates, cyanoacrylates, malonic acid anilides, malonic acid esters, formamidines and the like. These may be used alone or in combination of two or more. Among these, benzotriazoles, triazines, or ultraviolet absorbers having a maximum molar extinction coefficient ε _max of 1200 dm ³ · mol ^-1 cm ^-1 or less at a wavelength of 380 to 450 nm are preferable.

Benzotriazoles are preferably used because they have a high effect of suppressing deterioration of optical properties such as coloring due to exposure to ultraviolet rays. Examples of benzotriazoles include 2- (2H-benzotriazole-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol (manufactured by BASF; trade name: TINUVIN329), 2- (2H-). Benzotriazole-2-yl) -4,6-bis (1-methyl-1-phenylethyl) phenol (manufactured by BASF; trade name TINUVIN234) and the like are preferable.

Further, an ultraviolet absorber having a maximum molar extinction coefficient ε _max of 1200 dm ³ · mol ^-1 cm ^-1 or less at a wavelength of 380 to 450 nm can suppress the yellowness of the lens. Examples of such an ultraviolet absorber include 2-ethyl-2'-ethoxy-oxalanilide (manufactured by Clariant Japan Co., Ltd .; trade name: Sandeuboa VSU).
Among these UV absorbers, benzotriazoles are preferably used from the viewpoint of suppressing resin deterioration due to UV exposure.

Further, when it is desired to efficiently absorb a wavelength in the vicinity of a wavelength of 380 nm, a triazine-based ultraviolet absorber is preferably used. Examples of such an ultraviolet absorber include 2,4,6-tris (2-hydroxy-4-hexyloxy-3-methylphenyl) -1,3,5-triazine (manufactured by ADEKA; LA-F70). Can be mentioned.

The maximum value ε _max of the molar extinction coefficient of the ultraviolet absorber is measured as follows. 10.00 mg of an ultraviolet absorber is added to 1 L of cyclohexane and dissolved so that there is no undissolved substance by visual observation. This solution is injected into a quartz glass cell of 1 cm × 1 cm × 3 cm, and the absorbance at a wavelength of 380 to 450 nm is measured using a U-4341 spectrophotometer manufactured by Hitachi, Ltd. The maximum value ε _max of the molar extinction coefficient is calculated from the molecular weight (MVV) of the _ultraviolet absorber and the maximum value (Amax) of the measured absorbance by the following equation.

ε _max = [A _max / (10 × 10 ^-3 )] × M _UV

The amount of the ultraviolet absorber that can be contained in the lens is preferably 0.2 to 2.0 parts by mass, more preferably 0.5 to 1.5 parts by mass, and further preferably 0 with respect to 100 parts by mass of the methacrylic resin. It is .5 to 1.0 parts by mass.

Examples of the filler include calcium carbonate, talc, carbon black, titanium oxide, silica, clay, barium sulfate, magnesium carbonate and the like.

The heat deterioration inhibitor can prevent the heat deterioration of the resin by capturing the polymer radicals generated when exposed to high heat under a substantially oxygen-free state.
Examples of the heat deterioration inhibitor include 2-t-butyl-6- (3'-t-butyl-5'-methyl-hydroxybenzyl) -4-methylphenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd .; trade name: Sumilyzer GM). 2,4-dit-amyl-6- (3', 5'-dit-amyl-2'-hydroxy-α-methylbenzyl) phenyl acrylate (manufactured by Sumitomo Chemical Co., Ltd .; trade name Sumilyzer GS) and the like are preferable.

The light stabilizer is a compound that is said to have a function of capturing radicals mainly generated by oxidation by light. Suitable light stabilizers include hindered amines such as compounds having a 2,2,6,6-tetraalkylpiperidine skeleton.

Examples of the lubricant include stearic acid, behenic acid, stearoamic acid, methylenebisstearoamide, hydroxystearic acid triglyceride, paraffin wax, ketone wax, octyl alcohol, hydrogenated oil and the like.

Examples of the release agent include higher alcohols such as cetyl alcohol and stearyl alcohol; and glycerin higher fatty acid esters such as stearic acid monoglyceride and stearic acid diglyceride. In the present invention, it is preferable to use higher alcohols and glycerin fatty acid monoester in combination as a release agent. When the higher alcohols and the glycerin fatty acid monoester are used in combination, the ratio is not particularly limited, but the amount of the higher alcohols used: the amount of the glycerin fatty acid monoester used is 2.5: 1 to 3. 5: 1 is preferable, and 2.8: 1 to 3.2: 1 are more preferable.

As the polymer processing aid, polymer particles having a particle diameter of 0.05 to 0.5 μm, which can be usually produced by an emulsion polymerization method, are used. The polymer particles may be single-layer particles made of a polymer having a single composition ratio and a single extreme viscosity, or may be multilayer particles made of two or more kinds of polymers having different composition ratios or extreme viscositys. You may. Among these, particles having a two-layer structure having a polymer layer having a low ultimate viscosity in the inner layer and a polymer layer having a high ultimate viscosity of 5 dl / g or more in the outer layer are preferable. The polymer processing aid preferably has an ultimate viscosity of 3 to 6 dl / g. If the ultimate viscosity is too small, the effect of improving moldability tends to be low. If the ultimate viscosity is too large, the moldability tends to decrease.

Examples of the impact resistance modifier include a core-shell type modifier containing acrylic rubber or a diene rubber as a core layer component; and a modifier containing a plurality of rubber particles.

As the organic dye, a compound having a function of converting ultraviolet rays into visible light is preferably used.

Examples of the light diffusing agent and the matting agent include glass fine particles, polysiloxane-based crosslinked fine particles, crosslinked polymer fine particles, talc, calcium carbonate, barium sulfate and the like.

Examples of the fluorescent substance include fluorescent pigments, fluorescent dyes, fluorescent white dyes, fluorescent whitening agents, and fluorescent bleaching agents.

Antioxidants, heat deterioration inhibitors, UV absorbers, light stabilizers, lubricants, mold release agents, polymer processing aids, antistatic agents, flame retardants, dyes, and light diffusions that can be contained in the lenses of the present invention. The total amount of the agent, the organic dye, the matting agent, the impact resistance modifier, and the phosphor is preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less, and most preferably. It is 1% by mass or less.

Other polymers include polyolefin resins such as polyethylene, polypropylene, polybutene-1, poly-4-methylpentene-1, polynorbornene; ethylene-based ionomers; polystyrene, styrene-maleic anhydride copolymers, high-impact polystyrene, etc. Styrene-based resins such as AS resin, ABS resin, AES resin, AAS resin, ACS resin, MBS resin; methyl methacrylate-based polymer, methyl methacrylate-styrene copolymer; polyester resin such as polyethylene terephthalate and polybutylene terephthalate; nylon 6 , Nylon 66, polyamide such as polyamide elastomer; polycarbonate, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, polyacetal, vinylidene fluoride, polyurethane, modified polyphenylene ether, polyphenylene sulfide, silicone-modified resin; Acrylic rubber, silicone rubber; styrene-based thermoplastic polymers such as SEPS, SEBS, and SIS; olefin-based rubbers such as IR, EPR, and EPDM. The amount of the other polymer that can be contained in the lens of the present invention is preferably 5% by mass or less, more preferably 1.5% by mass or less, still more preferably 0.5% by mass or less, and most preferably 0% by mass. ..

The lens of the present invention has an amount of terminal double bonds of less than 0.012 mol%, preferably less than 0.011 mol%, relative to the methacrylic resin. The amount of terminal double bond is a value _DL determined as follows. The lens is dissolved in deuterated chloroform to a concentration of 15 to 20% by mass to obtain a solution. Add 10% by mass of tris (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedinate) europium to the solution to the mass of the lens. do. The solution is integrated and measured by ¹ H-NMR for 12 hours or more. From the obtained ¹ H-NMR spectrum, the total intensity _XL of the signal derived from the terminal double bond (resonance frequency 5.5 ppm and 6.2 ppm) and the signal derived from the methoxy group of the methyl methacrylate main chain. The integrated intensity Y _L at (resonance frequency 3.6 ppm) is measured, and the amount _DL of the terminal double bond is calculated by the following equation.
_{DL = [(XL / 2) / (Y L / 3} )] × 100

The lens of the present invention has a triad syndiotacticity (rr) of 50 to 65%, preferably 53 to 63%, more preferably 55 to 61%, still more preferably 56 to 60%. The triad syndiotacticity (rr) of the lens is 0 when the lens is dissolved in deuterated chloroform, ¹ H-NMR spectrum is measured at 30 ° C. for the solution, and the TMS is 0 ppm from the spectrum. The area (X) in the region of 0.6 to 0.95 ppm and the area (Y) in the region of 0.6 to 1.35 ppm can be measured and calculated by the formula: (X / Y) × 100.

The lens of the present invention has a thermogravimetric retention rate of 98% by mass or more, preferably 98.5% by mass or more, more preferably 98.7% by mass or more when exposed to 290 ° C. for 15 minutes in a nitrogen gas atmosphere. be. The thermogravimetric retention rate of the lens is a value determined as follows.
A thermal weight measuring device (manufactured by Shimadzu Corporation, TGA) is placed in a nitrogen gas atmosphere, the lens or lens debris to be measured is set, dry nitrogen is flowed at a flow rate of 50 ml / min, and the temperature from 50 ° C to 290 ° C is 20 ° C. The temperature is raised at / min, and then the mass change of the measurement target is recorded under the condition of holding at 290 ° C. for 20 minutes in a nitrogen atmosphere. The ratio of the mass (Y _2L ) after holding at 290 ° C. for 15 minutes to the mass (Y _1L ) at 50 ° C. was defined as the thermogravimetric retention rate.
Thermal weight retention (% by mass) = (Y _2L / Y _1L ) x 100 (% by mass)
The higher the thermogravimetric retention rate, the higher the heat-decomposability.

The lens of the present invention has a haze of preferably 3.0% or less, more preferably 2.0% or less, still more preferably 1.5% or less when converted to a thickness of 3.2 mm.

The lens of the present invention has a weight average molecular weight Mw of preferably 50,000 to 150,000, more preferably 52,000 to 120,000, and even more preferably 55,000 to 100,000.

In the lens of the present invention, the ratio Mw / Mn of the weight average molecular weight Mw to the number average molecular weight is preferably 1.2 to 2.0, more preferably 1.4 to 2.0. The weight average molecular weight and the number average molecular weight of the lens are values obtained by converting the chromatogram measured by gel permeation chromatography (GPC) into the molecular weight of standard polystyrene.

The lens of the present invention has a melt flow rate of preferably 0.1 g / 10 minutes or more, more preferably 0.2 to 30 g / 10 minutes, still more preferably 0.5 to 0 under the conditions of 230 ° C. and a 3.8 kg load. 20 g / 10 minutes, most preferably 0.5 to 10 g / 10 minutes. The melt flow rate of the lens was measured according to JIS K7210 under the conditions of 230 ° C., 3.8 kg load and 10 minutes.

In the lens of the present invention, the lower limit of the glass transition temperature is preferably 123 ° C., and the upper limit of the glass transition temperature is preferably 130 ° C., more preferably 129 ° C. The glass transition temperature of the lens is an intermediate point glass transition temperature (Tmg) determined based on the measurement data by differential scanning calorimetry (DSC).

The lens of the present invention has a light transmittance at 450 nm when the optical path length is converted to 3 mm, before and after 1000 hours of irradiation with ultraviolet rays at a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² . In any case, it is 91% or more, preferably 92% or more.

In the lens of the present invention, the amount of bound sulfur atoms is preferably less than 0.25 mol%, more preferably less than 0.15 mol% with respect to the methacrylic resin. The amount of bound sulfur atom in the lens is a value _SL determined as follows. Dissolve the lens in chloroform to obtain a solution. This solution is added to n-hexane to give a precipitate. The precipitate is dried at 80 ° C. for at least 12 hours under vacuum. An appropriate amount of the obtained dried product is precisely weighed, set in a sulfur combustion device, decomposed in a reaction furnace at a temperature of 400 ° C., and the generated gas is passed through a furnace at a temperature of 900 ° C., and then a 0.3% hydrogen peroxide solution is used. Absorb with. The obtained liquid (decomposed gas aqueous solution) is appropriately diluted with pure water, and sulfate ions are quantified by ion chromatography (ICS-1500 manufactured by DIONEX, column: AS12A). Calculate the mass _WL (mass%) of sulfur atoms per mass of the dried product. Next, the amount _SL (mol%) of the bonded sulfur atom is calculated by the following formula.
SL ₌ WL × ( _100/32 )

In the lens of the present invention, the amount of residual methyl methacrylate is 1.0% by mass or less, more preferably 0.5% by mass or less, still more preferably 0.3% by mass or less, based on the mass of the lens. ..

In the lens of the present invention, the amount of the structural unit derived from methyl methacrylate is preferably 90% by mass or more, more preferably 95% by mass or more, still more preferably 98% by mass or more, based on the mass of the methacrylic resin. It is more preferably 99% by mass or more, and most preferably 100% by mass. The amount of structural units derived from methyl methacrylate is determined by ^{1 1} H-NMR.

The lens of the present invention is preferably suitable for lighting, more preferably for LED lighting. Illumination lenses are typically used for light distribution, light collection, or diffusion purposes. The light distribution lens is for bending the light emitted from the LED element or the like. Examples of the light distribution lens include a Fresnel lens processed with the center shifted, a combination lens of a Fresnel lens and a one-sided prism lens, and the like. The condenser lens is for collecting the light emitted by the LED element or the like. Examples of the condenser lens include a convex lens, a Fresnel lens, and a linear Fresnel lens. As a high-efficiency condensing lens, a lens shape that totally reflects light at a portion having a large angle with the irradiation direction axis on the inner surface of the lens and a lens emission surface as a microlens array can be mentioned. The diffusing lens is for diffusing the light emitted from the LED element or the like. Examples of the diffuser lens include a concave lens and the like. The lens of the present invention may be a biconvex lens, a biconcave lens, or a meniscus lens, or may be a spherical lens or an aspherical lens. The lens of the present invention may be a lens array in which a large number of lens elements are arranged as shown in FIG.

In the method for producing a lens of the present invention, a predetermined methacrylic resin, a hinderphenol-based antioxidant, and, if necessary, a compound containing a metal element having an atomic number of 20 or less are melt-kneaded at a predetermined ratio to form a resin. The composition is obtained, and the obtained resin composition is injection-molded.

Examples of the apparatus for melt-kneading include a kneader luder, an extruder, a mixing roll, a Banbury mixer and the like, but in the manufacturing method of the present invention, a single-screw extruder or a twin-screw extruder is used. Is preferable. In the single-screw extruder, the cylinder heating temperature is usually set to 261 to 285 ° C, preferably 261 ° C to 275 ° C. In the twin-screw extruder, the cylinder heating temperature is usually set to 261 to 280 ° C, preferably 261 ° C to 275 ° C.

The melt kneading is carried out in a range where the characteristic mechanical energy SME is preferably 50 to 100 kJ / kg, more preferably 55 to 90 kJ / kg, further preferably 57 to 87 kJ / kg, and most preferably 60 to 83 kJ / kg. The characteristic mechanical energy SME is calculated by the following formula (see Non-Patent Document 1).
SME [kJ / kg] = τ × Ns / Q
τ = extruder torque [Nm]
Ns = screw rotation speed [min ^-1 ]
Q = Extrusion amount [kg / min]

The resin composition obtained by melt-kneading can be in the form of pellets or the like in order to enhance convenience during storage, transportation, or molding.

Injection molding usually goes through a melt plasticization step, a filling / holding step, a cooling step, and a mold removal step. In the cooling step, the cavity can be made smaller by applying a force from the outside to the mold according to the volume shrinkage of the filled resin composition (injection compression molding method). In injection compression molding, a low links method, a micromolder method, a sandwich press method, a direct pressure method, a two-stage direct pressure method, or the like can be adopted.

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The physical property values and the like were measured by the following methods.

(Metal element content)
10 ml of nitric acid was added to 0.15 g of the lens, and the microwave was irradiated at 220 ° C. for 25 minutes using the microwave irradiation device ETHOS-1600. After allowing to cool, ion-exchanged water was added to the obtained solution to obtain a 20 ml solution. The obtained solution was quantitatively analyzed for metal elements using an ICP emission spectrophotometer (Vista Pro manufactured by SII). The metal element content (parts by mass) with respect to 100 parts by mass of the methacrylic resin was calculated.

(Amount of terminal double bond)
The lens was dissolved in deuterated chloroform to a concentration of 15 to 20% by mass to obtain a solution. Add 10% by mass of tris (6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedinate) europium to the solution to the mass of the lens. did. The solution was integrated and measured over 12 hours using NMR (JNM-GX270 manufactured by JEOL Ltd.). From the obtained ¹ H-NMR spectrum, the total intensity _XL of the signal derived from the terminal double bond (resonance frequency 5.5 ppm and 6.2 ppm) and the signal derived from the methoxy group of the methyl methacrylate main chain (resonance frequency 5.5 ppm and 6.2 ppm). The integrated intensity Y _L (resonance frequency 3.6 ppm) was measured, and the terminal double bond amount _DL [mol%] of the methacrylic resin was calculated by the following equation.
_DL = [(3 × _{XL) / (2 × Y L )} ] × 100

(Atomic weight of bound sulfur)
The lens was dissolved in chloroform to give a solution and this solution was added to n-hexane to give a precipitate. The obtained precipitate was dried at 80 ° C. for 12 hours or more under vacuum. An appropriate amount of the obtained dried product is precisely weighed, set in a sulfur combustion device, decomposed in a reaction furnace at a temperature of 400 ° C., the generated gas is passed through a furnace at 900 ° C., and then absorbed with 0.3% hydrogen peroxide solution. did. The obtained liquid was appropriately diluted with pure water, and sulfate ions were quantified by ion chromatography (ICS-1500 manufactured by DIONEX, column: AS12A). The mass _WL (mass%) of sulfur atoms per mass of the dried product was calculated. Then, the amount _SL (mol%) of the bonded sulfur atom was calculated by the following formula.
_{SL =} ( _WL / 32) x 100

(Weight average molecular weight Mw, number average molecular weight Mn)
For Mw and Mn, the chromatogram was measured by gel permeation chromatography (GPC) under the following conditions, and the values converted into the molecular weight of standard polystyrene were calculated.
GPC device: HLC-8320 manufactured by Tosoh Corporation
Detector: Differential refractive index detector Column: Two TSKgel SuperMultipore HZM-M manufactured by Tosoh Corporation and SuperHZ4000 connected in series were used.
Eluent: Tetrahydrofuran Eluent flow rate: 0.35 ml / min Column temperature: 40 ° C
Calibration curve: Created using data of 10 standard polystyrene points

(Triad Syngeo Tacticity (rr))
Using a nuclear magnetic resonance apparatus (ULTRA SHIELD 400 PLUS manufactured by Bruker), ¹ H-NMR was measured under the following conditions, and the area of the region of 0.6 to 0.95 ppm when TMS was 0 ppm ( X), the area (Y) in the region of 0.6 to 1.35 ppm was measured, and the value calculated by the formula: (X / Y) × 100 was taken as the triad syndiotacticity (rr) (%). ..
Solvent: Deuterated chloroform Measurement nuclide: ¹ H
Measurement temperature: Room temperature Accumulation number: 64 times

(Amount of residual methyl methacrylate monomer)
A column (INERT CAP 1 (df = 0.4 μm, 0.25 mm I.D. × 60 m) manufactured by GL Sciences Inc.) was connected to the gas chromatograph, and analysis was performed under the following conditions, and the calculation was performed based on the analysis.
Injection temperature: 250 ° C
detector temperature: 250 ° C
Column temperature condition:
Initial temperature: 60 ° C
Initial temperature holding time: 5 minutes Heating rate: 10 ° C / min Maximum temperature: 250 ° C
Maximum temperature retention time: 10 minutes

(Melt flow rate (MFR))
Measured according to JIS K7210 under the conditions of 230 ° C., 3.8 kg load and 10 minutes.

(Thermogravimetric retention rate)
For the lens, use a thermogravimetric measuring device (manufactured by Shimadzu Corporation, TGA-50 (product number)) to raise the temperature from 50 ° C to 290 ° C at 20 ° C / min under a nitrogen atmosphere at a nitrogen flow rate of 50 ml / min. After that, the mass change was recorded under the condition of holding at 290 ° C. for 20 minutes in a nitrogen atmosphere. Based on the mass (X _1c ) at 50 ° C. (thermogravimetric retention rate 100% by mass) and the mass (X _2c ) when held at 290 ° C. for 15 minutes, the heat-resistant decomposition property is evaluated by the following formula. did.
Thermal weight retention (% by mass) = (X _2c / X _1c ) x 100 (% by mass)

(Glass transition temperature (Tmg))
In accordance with JIS K7121, using a differential scanning calorimetry device (manufactured by Shimadzu Corporation, DSC-50 (product number)), the temperature is once raised to 230 ° C, then cooled to room temperature, and then from room temperature to 230 ° C. The DSC curve was measured under the condition of raising the temperature at 10 ° C./min. The midpoint glass transition temperature was determined from the DSC curve measured during the second temperature rise.

(Total light transmittance)
The total light transmittance (converted to an optical path length of 3.2 mm) of the lens was measured using a haze meter (HM-150, manufactured by Murakami Color Research Institute) according to JIS K7361-1.

(Light transmittance of 450 nm)
Using an ultraviolet-visible near-infrared spectrophotometer (Product No .: V-670 manufactured by JASCO Corporation), the optical transmittance with an optical path length of 3 mm and a wavelength of 450 nm was measured.

(Haze)
Haze was measured using a haze meter (HM-150, manufactured by Murakami Color Research Institute) in accordance with JIS K7136.

(Color difference ΔE)
Using a super UV tester (manufactured by Iwasaki Electric Co., Ltd .; SUV-W161), before and after irradiating ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² . , The color difference ΔE was calculated by the following formula from the difference (ΔL, Δa, Δb) of each value of L, a, and b in the Lab color space of the lens array.
ΔE = [(ΔL) 2+ (Δa) 2+ (Δb) 2] 1/2
The values of L, a and b in the Lab color space were determined using an SM color computer (manufactured by Suga Test Instruments Co., Ltd .; M-4). The smaller the color difference, the better the weather resistance.

(UV deformation resistance)
Using a super UV tester (manufactured by Iwasaki Electric Co., Ltd .; SUV-W161), before and after irradiating with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² . The lens array was placed on a flat surface with the mirror surface side down, and the size of the gap between the mirror surface and the flat surface was measured using a feeler gauge, and the difference was calculated.
◯: The number of lens arrays with a difference of 0.3 mm or more is less than 40% of the total ×: The number of lens arrays with a difference of 0.3 mm or more is 40% or more of the total

A methacrylic resin having the following physical characteristics was prepared.
Methacrylic resin [Aa]: Mw = 68000, Mw / Mn = 1.06, triad syndiotacticity (rr) = 73%, glass transition temperature = 130 ° C., ratio of structural units derived from methyl methacrylate = 100. Mass%, terminal double bond amount = 0 mol%, bond sulfur atom amount = 0 mol%, Al element content = 5.0 ppm, Li element content = 0.5 ppm, metal element with atomic number 20 or less Content = 5.5 ppm; Anion solution polymerization method;

Methacrylic resin [A-b]: Mw = 82000, Mw / Mn = 1.92, triad syndiotacticity (rr) = 51%, glass transition temperature = 120 ° C., ratio of structural units derived from methyl methacrylate = 100 mass. %, End double bond amount = 0.014 mol%, Bonded sulfur atom amount = 0.160 mol%, Al element content = 0 ppm, Li element content = 0 ppm, Metal element with atomic number 20 or less Content = 0 ppm; Radical continuous massive polymerization method;

Methacrylic resin [A-c]: Mw = 78000, Mw / Mn = 1.52, triad syndiotacticity (rr) = 56%, glass transition temperature = 122 ° C., ratio of structural units derived from methyl methacrylate = 100 mass. %, End double bond amount = 0.011 mol%, Bonded sulfur atom amount = 0.130 mol%, Al element content = 1.0 ppm, Li element content = 0.1 ppm, atomic number 20 or less Metal element content = 1.1 ppm; Blend of 20 parts by mass of methacrylic resin [A-a] and 80 parts by mass of methacrylic resin [A-b];

Methacrylic resin [A-d]: Mw = 87000, Mw / Mn = 1.78, triad syndiotacticity (rr) = 48%, glass transition temperature = 117 ° C., proportion of structural units derived from methyl methacrylate = 98. 5% by mass, ratio of structural units derived from methyl acrylate = 1.5% by mass, terminal double bond amount = 0.020 mol%, amount of bound sulfur atom = 0.015 mol%, Al element content = 0 ppm, Li element content = 0 ppm, content of metal element with atomic number 20 or less = 0 ppm; Radical continuous massive polymerization method;

Methacrylic resin [A-e]: Mw = 68000, Mw / Mn = 1.06, triad syndiotacticity (rr) = 73%, glass transition temperature = 130 ° C., ratio of structural units derived from methyl methacrylate = 100 mass. %, End double bond amount = 0 mol%, Bonded sulfur atom amount = 0 mol%, Al element content = 1000 ppm, Li element content = 320 ppm, Metal element content with atomic number 20 or less = 1320 ppm Anion solution polymerization method;

Methacrylic resin [A-f]: Mw = 76000, Mw / Mn = 1.50, triad syndiotacticity (rr) = 58%, glass transition temperature = 123 ° C., ratio of structural units derived from methyl methacrylate = 100 mass. %, End double bond amount = 0.010 mol%, Bonded sulfur atom amount = 0.115 mol%, Al element content = 1.5 ppm, Li element content = 0.2 ppm, atomic number 20 or less Metal element content = 1.7 ppm; blend of 30 parts by mass of methacrylic resin [A-a] and 70 parts by mass of methacrylic resin [A-b];

Methacrylic resin [A-g]: Mw = 73000, Mw / Mn = 1.50, triad syndiotacticity (rr) = 60%, glass transition temperature = 124 ° C., ratio of structural units derived from methyl methacrylate = 100 mass. %, End double bond amount = 0.008 mol%, Bonded sulfur atom amount = 0.100 mol%, Al element content = 2.0 ppm, Li element content = 0.2 ppm, atomic number 20 or less Metal element content = 2.2 ppm; Blend of 40 parts by mass of methacrylic resin [A-a] and 60 parts by mass of methacrylic resin [A-b];

The following antioxidants were prepared.
Antioxidant [Ca]: 2,6-bis (1,1-dimethylethyl) -4-methylphenol (manufactured by Wako Pure Chemical Industries, Ltd .; BHT)
Antioxidant [Cb]: Pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] (manufactured by BASF; trade name IRGANOX1010)

Example 1
Mix 100 parts by mass of methacrylic resin [Ac] and 0.03 parts by mass of antioxidant [Ca], and use a twin-screw extruder (manufactured by Technobel Co., Ltd., trade name: KZW20TW-45MG-NH-600) to form a cylinder. A resin composition was obtained by melt-kneading at a heating temperature of 260 ° C. and a characteristic mechanical energy of SME73 kJ / kg.
A pair of long sides of a fixed mold is placed in a cavity between a fixed mold having a square frennel lens pattern arranged in 6 rows vertically and 4 rows horizontally and a movable mold having a mirror surface facing the fixed mold. The melt-plasticized resin composition was filled through the gates provided in the vicinity of the central portion. After that, the resin composition is cooled and cured, and then released from the mold. The height of the uneven groove having a Fresnel lens pattern of a square having a side of 240 mm and a pitch of 0.38 mm in 6 rows and 4 rows is 0.23 mm. A lens array (1) having a thin portion having a thickness of 0.6 mm was obtained (FIG. 1). The lens array (1) was distortion-free and transparent to the naked eye. The lens array (1) has an Al element content = 1.0 ppm, a Li element content = 0.1 ppm, a metal element content of atomic number 20 or less = 1.1 ppm, and a terminal double bond content of 0. 0.011 mol%, amount of bound sulfur atom less than 0.130 mol%, weight average molecular weight 78000, triad syndiotacticity (rr) 56%, proportion of structural units derived from methyl methacrylate is the total structural unit 100% by mass, residual methyl methacrylate amount is 0.20% by mass, melt flow rate is 2.3 g / 10 minutes, heat weight retention rate is 98.0%, glass transition temperature is 122 ° C, and optical path length. When converted to 3.2 mm, the total light transmittance was 92%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 92%, and the haze was 0.1%. The lens array (1) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then the light transmittance at a wavelength of 450 nm when the optical path length is converted to 3 mm. Was 92% and haze was 0.1%. The lens array (1) had a color difference of 0.2 and a UV deformation resistance of 〇.

Example 2
A lens array (2) was obtained by the same method as in Example 1 except that 0.03 part by mass of the antioxidant [Ca] was changed to 0.15 part by mass of the antioxidant [Cb]. The lens array (2) was distortion-free and transparent to the naked eye. The lens array (2) has an Al element content = 1.0 ppm, a Li element content = 0.1 ppm, a metal element content of atomic number 20 or less = 1.1 ppm, and a terminal double bond content of 0. 0.011 mol%, amount of bound sulfur atom less than 0.130 mol%, weight average molecular weight 78000, triad syndiotacticity (rr) 56%, proportion of structural units derived from methyl methacrylate is the total structural unit 100% by mass, residual methyl methacrylate amount is 0.20% by mass, melt flow rate is 2.3 g / 10 minutes, heat weight retention rate is 98.0%, glass transition temperature is 122 ° C, and optical path length. When converted to 3.2 mm, the total light transmittance was 92%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 92%, and the haze was 0.1%. This lens array (2) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 92% and the haze was 0.1%. The lens array (2) had a color difference of 0.2 and a deformation resistance of 〇.

Example 3
Example 1 except that 100 parts by mass of the methacrylic resin [Ac] and 0.03 parts by mass of the antioxidant [Ca] were changed to 100 parts by mass of the methacrylic resin [Af] and 0.05 parts by mass of the antioxidant [Ca]. The lens array (3) was obtained in the same way. The lens array (3) was undistorted and transparent to the naked eye. The lens array (3) has an Al element content = 1.5 ppm, a Li element content = 0.2 ppm, a metal element content of atomic number 20 or less = 1.7 ppm, and a terminal double bond content of 0. .010 mol%, amount of bound sulfur atom less than 0.115 mol%, weight average molecular weight 76000, triad syndiotacticity (rr) 58%, proportion of structural units derived from methyl methacrylate is the total structural unit 100% by mass, residual methyl methacrylate amount is 0.25% by mass, melt flow rate is 2.1 g / 10 minutes, heat weight retention rate is 98.5%, glass transition temperature is 123 ° C, and optical path length. When converted to 3.2 mm, the total light transmittance was 92%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 92%, and the haze was 0.1%. This lens array (3) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 92% and the haze was 0.1%. The lens array (3) had a color difference of 0.2 and a deformation resistance of 〇.

Example 4
Example 2 except that 100 parts by mass of the methacrylic resin [Ac] and 0.03 parts by mass of the antioxidant [Ca] were changed to 100 parts by mass of the methacrylic resin [Ag] and 0.06 parts by mass of the antioxidant [Ca]. The lens array (4) was obtained in the same way. The lens array (4) was distortion-free and transparent to the naked eye. The lens array (4) has an Al element content = 2.0 ppm, a Li element content = 0.2 ppm, a metal element content of atomic number 20 or less = 2.2 ppm, and a terminal double bond content of 0. .008 mol%, the amount of bound sulfur atom is less than 0.100 mol%, the weight average molecular weight is 73000, the triad syndiotacticity (rr) is 60%, and the proportion of structural units derived from methyl methacrylate is the total structural unit. 100% by mass, residual methyl methacrylate amount is 0.25% by mass, melt flow rate is 1.9 g / 10 minutes, heat weight retention rate is 98.7%, glass transition temperature is 124 ° C., and optical path length. When converted to 3.2 mm, the total light transmittance was 92%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 92%, and the haze was 0.1%. This lens array (4) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 92% and the haze was 0.1%. The lens array (4) had a color difference of 0.2 and a deformation resistance of 〇.

Example 5
2. 100 parts by mass of methacrylic resin [Ac], 0.03 parts by mass of antioxidant [Ca], 27.5 parts by mass of methacrylic resin [Aa], 70.0 parts by mass of methacrylic resin [Ab], and methacryl resin [Ae]. A lens array (5) was obtained by the same method as in Example 1 except that the amount was changed to 5 parts by mass and 0.05 parts by mass of the antioxidant [Ca]. The lens array (5) was distortion-free and transparent to the naked eye. The lens array (5) has an Al element content = 26.4 ppm, a Li element content = 8.1 ppm, a metal element content with an atomic number of 20 or less = 34.5 ppm, and a terminal double bond content of 0. .010 mol%, amount of bound sulfur atom less than 0.115 mol%, weight average molecular weight 76000, triad syndiotacticity (rr) 58%, proportion of structural units derived from methyl methacrylate is the total structural unit 100% by mass, residual methyl methacrylate amount is 0.25% by mass, melt flow rate is 2.1 g / 10 minutes, heat weight retention rate is 98.2%, glass transition temperature is 123 ° C, and optical path length. When converted to 3.2 mm, the total light transmittance was 91%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 91%, and the haze was 0.1%. This lens array (5) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 91% and the haze was 0.1%. The lens array (5) had a color difference of 0.2 and a deformation resistance of 〇.

Comparative Example 1
A lens array (6) was obtained by the same method as in Example 1 except that 100 parts by mass of the methacrylic resin [Ac] and 0.03 parts by mass of the antioxidant [Ca] were changed to 100 parts by mass of the methacrylic resin [Aa]. .. The lens array (6) was transparent to the naked eye, but was distorted. The lens array (6) has an Al element content = 5.0 ppm, a Li element content = 0.5 ppm, a metal element content of atomic number 20 or less = 5.5 ppm, and a terminal double bond content of 0. .000 mol%, amount of bound sulfur atom less than 0.000 mol%, weight average molecular weight 68000, triad syndiotacticity (rr) 73%, proportion of structural units derived from methyl methacrylate is the total structural unit 100% by mass, residual methyl methacrylate amount is 0.15% by mass, melt flow rate is 1.4 g / 10 minutes, heat weight retention rate is 64.9%, glass transition temperature is 130 ° C., and optical path length. When converted to 3.2 mm, the total light transmittance was 92%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 92%, and the haze was 0.1%. This lens array (6) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 90% and the haze was 0.5%. The lens array (6) had a color difference of 0.6 and a deformation resistance of 〇.

Comparative Example 2
Example 1 except that 100 parts by mass of the methacrylic resin [Ac] and 0.03 parts by mass of the antioxidant [Ca] were changed to 100 parts by mass of the methacrylic resin [Aa] and 0.15 parts by mass of the antioxidant [Ca]. The lens array (7) was obtained in the same way. The lens array (7) was transparent to the naked eye, but was distorted. The lens array (7) has an Al element content = 5.0 ppm, a Li element content = 0.5 ppm, a metal element content of atomic number 20 or less = 5.5 ppm, and a terminal double bond content of 0. .000 mol%, amount of bound sulfur atom less than 0.000 mol%, weight average molecular weight 68000, triad syndiotacticity (rr) 73%, proportion of structural units derived from methyl methacrylate is the total structural unit 100% by mass, residual methyl methacrylate amount is 0.15% by mass, melt flow rate is 1.4 g / 10 minutes, heat weight retention rate is 98.9%, glass transition temperature is 130 ° C., and optical path length. When converted to 3.2 mm, the total light transmittance was 92%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 92%, and the haze was 0.1%. This lens array (7) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 90% and the haze was 0.2%. The lens array (7) had a color difference of 0.6 and a deformation resistance of 〇.

Comparative Example 3
Example 1 except that 100 parts by mass of the methacrylic resin [Ac] and 0.03 parts by mass of the antioxidant [Ca] were changed to 100 parts by mass of the methacrylic resin [Ab] and 0.15 parts by mass of the antioxidant [Ca]. The lens array (8) was obtained in the same way. The lens array (8) was distortion-free and transparent to the naked eye. The lens array (8) has an Al element content = 0.0 ppm, a Li element content = 0.0 ppm, a metal element content of atomic number 20 or less = 0.0 ppm, and a terminal double bond content of 0. .014 mol%, amount of bound sulfur atom less than 0.160 mol%, weight average molecular weight 82000, triad syndiotacticity (rr) 51%, proportion of structural units derived from methyl methacrylate is the total structural unit 100% by mass, residual methyl methacrylate amount is 0.25% by mass, melt flow rate is 2.6 g / 10 minutes, heat weight retention rate is 96.6%, glass transition temperature is 120 ° C., and optical path length. When converted to 3.2 mm, the total light transmittance was 92%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 92%, and the haze was 0.1%. This lens array (8) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 92% and the haze was 0.1%. The lens array (8) had a color difference of 0.1 and a deformation resistance of ×.

Comparative Example 4
Example 1 except that 100 parts by mass of the methacrylic resin [Ac] and 0.03 parts by mass of the antioxidant [Ca] were changed to 100 parts by mass of the methacrylic resin [Ab] and 0.15 parts by mass of the antioxidant [Cb]. The lens array (9) was obtained in the same way. The lens array (9) was distortion-free and transparent to the naked eye. The lens array (9) has an Al element content = 0.0 ppm, a Li element content = 0.0 ppm, a metal element content of atomic number 20 or less = 0.0 ppm, and a terminal double bond content of 0. .014 mol%, amount of bound sulfur atom less than 0.160 mol%, weight average molecular weight 82000, triad syndiotacticity (rr) 51%, proportion of structural units derived from methyl methacrylate is the total structural unit 100% by mass, residual methyl methacrylate amount is 0.25% by mass, melt flow rate is 2.6 g / 10 minutes, heat weight retention rate is 96.5%, glass transition temperature is 120 ° C., and optical path length. When converted to 3.2 mm, the total light transmittance was 92%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 92%, and the haze was 0.1%. This lens array (9) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 92% and the haze was 0.1%. The lens array (9) had a color difference of 0.1 and a deformation resistance of ×.

Comparative Example 5
100 parts by mass of methacrylic resin [Ac], 0.03 parts by mass of antioxidant [Ca], 24 parts by mass of methacrylic resin [Aa], 70 parts by mass of methacrylic resin [Ab], 6 parts by mass of methacrylic resin [Ae], and antioxidant. A lens array (10) was obtained in the same manner as in Example 1 except that the agent [Ca] was changed to 0.15 parts by mass. The lens array (10) was distortion-free and transparent to the naked eye. The lens array (10) has an Al element content = 61.2 ppm, a Li element content = 19.3 ppm, a metal element content of atomic number 20 or less = 80.5 ppm, and a terminal double bond content of 0. .010 mol%, amount of bound sulfur atom less than 0.115 mol%, weight average molecular weight 76000, triad syndiotacticity (rr) 58%, proportion of structural units derived from methyl methacrylate is the total structural unit 100% by mass, residual methyl methacrylate amount is 0.25% by mass, melt flow rate is 2.1 g / 10 minutes, heat weight retention rate is 98.2%, glass transition temperature is 123 ° C, and optical path length. When converted to 3.2 mm, the total light transmittance was 85%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 85%, and the haze was 0.3%. This lens array (10) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 80% and the haze was 0.5%. The lens array (10) had a color difference of 0.2 and a deformation resistance of 〇.

Comparative Example 6
Example 1 except that 100 parts by mass of the methacrylic resin [Ac] and 0.03 parts by mass of the antioxidant [Ca] were changed to 100 parts by mass of the methacrylic resin [Ad] and 0.15 parts by mass of the antioxidant [Ca]. A lens array (11) was obtained in the same way. The lens array (11) was distortion-free and transparent to the naked eye. The lens array (11) has an Al element content = 0.0 ppm, a Li element content = 0.0 ppm, a metal element content of atomic number 20 or less = 0.0 ppm, and a terminal double bond content of 0. .020 mol%, amount of bound sulfur atom less than 0.015 mol%, weight average molecular weight 87,000, triad syndiotacticity (rr) 48%, proportion of structural units derived from methyl methacrylate is the total structural unit 98.5% by mass, residual methyl methacrylate amount is 0.30% by mass, melt flow rate is 2.8 g / 10 minutes, heat weight retention rate is 95.6%, glass transition temperature is 117 ° C, optical path. When the length was converted to 3.2 mm, the total light transmittance was 92%, and when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 92%, and the haze was 0.1%. This lens array (11) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 92% and the haze was 0.1%. The lens array (11) had a color difference of 0.1 and a deformation resistance of ×.

Comparative Example 7
100 parts by mass of methacrylic resin [Ac], 0.03 parts by mass of antioxidant [Ca], 70 parts by mass of methacrylic resin [Aa], 30 parts by mass of methacrylic resin [Ab], and 0.11 parts by mass of antioxidant [Ca]. A lens array (12) was obtained in the same manner as in Example 1 except that the mixture was changed to. The lens array (12) was transparent to the naked eye, but was distorted. The lens array (12) has an Al element content = 3.5 ppm, a Li element content = 0.4 ppm, a metal element content of atomic number 20 or less = 3.9 ppm, and a terminal double bond content of 0. .004 mol%, amount of bound sulfur atom less than 0.048 mol%, weight average molecular weight 72000, triad syndiotacticity (rr) 66%, proportion of structural units derived from methyl methacrylate is the total structural unit 100% by mass, residual methyl methacrylate amount is 0.50% by mass, melt flow rate is 1.6 g / 10 minutes, heat weight retention rate is 98.0%, glass transition temperature is 127 ° C., and optical path length. When converted to 3.2 mm, the total light transmittance was 92%, when the optical path length was converted to 3 mm, the light transmittance at a wavelength of 450 nm was 92%, and the haze was 0.1%. This lens array (12) is irradiated with ultraviolet rays for 1000 hours under the conditions of a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW / cm ² , and then light transmission at a wavelength of 450 nm when the optical path length is converted to 3 mm. The rate was 90% and the haze was 0.2%. The lens array (12) had a color difference of 0.6 and a deformation resistance of 〇.

As shown in the examples, the lens of the present invention has high heat resistance, high light transmittance, and little change in color.

Claims (6)

It contains 100 parts by mass of methacrylic resin, 5 × 10 ^-6 to 4 × 10 ^-3 parts by mass of a metal element having an atomic number of 20 or less, and 0.025 to 0.50 parts by mass of a hindered phenolic antioxidant.
The amount of terminal double bond is less than 0.012 mol% with respect to the methacrylic resin.
The triad syndiotacticity (rr) is 50% to 65%, and the thermogravimetric retention rate when exposed to 290 ° C. for 15 minutes in a nitrogen gas atmosphere is 98% by mass or more.
lens. When the glass transition temperature is 123 ° C to 130 ° C,
When the amount of residual methyl methacrylate is 1.0% by mass or less and the optical path length is converted to 3 mm, the light transmittance at a wavelength of 450 nm is such that ultraviolet rays have a black panel temperature of 95 ° C., a relative humidity of 50%, and an irradiation energy of 100 mW /. It is 91% or more both before and after irradiation with cm ² for 1000 hours.
The lens according to claim 1. The lens according to claim 1 or 2, wherein the amount of the bonded sulfur atom is less than 0.25 mol% with respect to the methacrylic resin. The lens according to any one of claims 1 to 3, wherein the weight average molecular weight Mw is 50,000 to 150,000. The lens according to any one of claims 1 to 4, wherein the content of the structural unit derived from methyl methacrylate is 99% by mass or more with respect to the methacrylic resin. The lens according to any one of claims 1 to 5, further comprising an ultraviolet absorber.

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