JP4860643B2 - Lens sheet and image display device including the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a lens sheet having transparency, heat resistance, light resistance and shock resistance balanced at a high level and further having a small specific gravity and lightness in weight, and to provide an image display device using the lens sheet. <P>SOLUTION: The lens sheet is configured by forming a lens portion comprising one or more lens groups on at least one surface of a transparent substrate comprising a &beta;-pinene polymer having a specific gravity of 0.85 to &lt;1.0 and a glass transition temperature of &ge;100&deg;C. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a lens sheet and an image display apparatus including the lens sheet, and in particular, a lightweight lens sheet having high heat resistance, high light resistance, and good dimensional stability, and an image display using such a lens sheet. It relates to the device.

  Conventionally, a lens sheet used in an image display device or the like has a large number of minute lens groups arranged on its surface, so that incident light is directed toward the front direction, which is a direction perpendicular to the sheet surface. It is known to have functions such as improving the extraction efficiency and widening the viewing angle.

  And, such a lens sheet is generally formed by integrally molding a prism row by a press molding operation on one side of a thermoplastic polymer transparent sheet, or on one side of a transparent polymer sheet, A prism array is integrally formed with an ultraviolet curable resin composition, and as a thermoplastic transparent polymer as a material, PMMA (refractive index: n = 1.49) or PC (n = 1.59) etc. are used (see Patent Documents 1 and 2).

  However, among these materials used, PMMA has high transparency and light resistance, but in addition to being easily changed in dimensions by water absorption, it has low impact resistance, is easy to break, has a large specific gravity, and is heavy. And so on. In addition, although PC has high impact resistance and heat resistance, it has drawbacks such as low transparency and light resistance, large specific gravity, and heavy weight.

  For this reason, lenses using alicyclic polymer hydrogenated materials as materials have been proposed as lens sheets that have improved these problems (see Patent Documents 3 and 4). Thus, when used as a lens sheet, they have high transparency, low water absorption, and high heat resistance, but have disadvantages such as low light resistance, large specific gravity and heavy weight compared to PMMA. is doing.

  Here, as the low specific gravity thermoplastic resin, so-called polyolefins such as polypropylene and polyethylene are known (see Patent Document 5), but since they are crystalline, they have low transparency and a low refractive index, And heat resistance is not enough. In addition, 4-methylpentene-1 polymer (see Patent Document 6) has a low specific gravity and a high melting point, but has a low refractive index and crystallinity, and does not satisfy optical performance such as birefringence. It was.

  In particular, as one of the market demands for this liquid crystal display device, there is an increase in size, and thus further weight reduction of the device has been demanded. And along with this increase in size and thickness, the lens sheet is increasingly bent by its own weight. For these reasons, development of a lighter lens sheet is required.

JP-A-8-190806 JP 2001-343507 A JP 2006-58531 A JP 2006-58522 A Japanese Patent Laid-Open No. 7-306319 Japanese Patent Laid-Open No. 2004-101641

  Here, the present invention has been made against the background of such circumstances, and the solution is to balance transparency, heat resistance, light resistance, and impact resistance at a high level, and further to specific gravity. It is to provide a small and lightweight lens sheet, and to provide an image display device using such a lens sheet.

  And as a result of intensive investigations to solve such problems, the present inventors have used a predetermined β-pinene polymer, whereby an intended lens sheet and an image display device using the same are obtained. It has been found that it can be advantageously obtained, and the present invention has been completed.

  That is, the present invention provides one or more lenses on at least one surface of a transparent substrate made of a β-pinene polymer having a specific gravity of 0.85 or more and less than 1.0 and a glass transition temperature of 100 ° C. or more. The gist of the lens sheet is characterized in that a lens portion composed of a group is formed.

  According to one of the desirable embodiments of the lens sheet according to the present invention, the β-pinene polymer is hydrogenated and ([hydrogenated olefinic double The number of bonds] / [number of olefinic double bonds in the polymer before hydrogenation]) × 100 is 95% or more.

  Furthermore, the gist of the present invention is also an image display device including the lens sheet as described above.

  In such a lens sheet according to the present invention and an illuminating device for an image display device using the same, since a predetermined β-pinene polymer is used as a material for forming the lens sheet, the β-pinene heavy component is used. Due to the excellent properties of the coalescence, the following effects can be achieved.

(1) Since the β-pinene polymer used as the lens sheet material is a polymer having a small specific gravity, it is possible to effectively reduce the weight of the target lens sheet.
(2) Since such β-pinene polymer has high heat resistance and low water absorption, it advantageously prevents the lens sheet from changing its dimensions due to the heat of the light source or from changing its dimensions due to water adsorption / desorption. It is possible to suppress the image quality change.
(3) The lens sheet according to the present invention can be advantageously thinned because the elastic modulus and impact resistance are highly balanced.
(4) Since the lens sheet according to the present invention has a low water vapor transmission rate, it is difficult for moisture to pass inside the lens sheet, and it is possible to suppress the occurrence of problems due to dew condensation inside.
(5) The lens sheet according to the present invention has a feature that no harmful gas is generated even if it is discarded and then incinerated.
(6) Since the β-pinene polymer used in the present invention has a low melt viscosity with respect to the molecular weight, it can give a finer lens shape.
(7) Since the lens sheet according to the present invention has high transparency, it is possible to obtain a clear image.
(8) Since the lens sheet according to the present invention has high light resistance, the lens sheet has an advantage that the performance is not deteriorated when used for a long time.
(9) The lens sheet according to the present invention has a feature that the color reproducibility is high because the Abbe number is large.
(10) Since the β-pinene polymer used in the present invention can be obtained from raw materials derived from natural products, it is a carbon neutral material and has environmentally friendly characteristics.

  By the way, the β-pinene polymer used as the lens sheet material in the present invention is a β-pinene polymer having a specific gravity of 0.85 or more and less than 1.0 and a glass transition temperature of 100 ° C. or more. . Here, the β-pinene polymer in the present specification and claims refers to a polymer (polymer) having a β-pinene content of 50% by mass or more. In the lens sheet according to the present invention, a β-pinene polymer having a β-pinene content of 60% by mass or more is advantageously used, and more preferably a β-pinene content of 70% by mass or more. -A pinene polymer is used.

  As the β-pinene used as a raw material for producing such β-pinene polymer, any conventionally known one can be used. For example, it is possible to use a terpene such as α-pinene collected from a plant or a petroleum-derived compound, as well as it can be directly used after purification from a plant such as pine or citrus. Β-pinene and the like produced according to a more known technique (for example, the technique disclosed in US Pat. No. 3,278,623) can also be used. The β-pinene polymer obtained using such plant-derived β-pinene is a carbon-neutral material. In this respect, the lens sheet according to the present invention forms a recycling society and global warming. It can contribute to prevention.

  Further, the β-pinene polymer used in the present invention may be a homopolymer of the above-described β-pinene, or at least one kind of other copolymerizable monomers with β-pinene. There is no problem even if it is a copolymer of. Examples of monomers copolymerizable with β-pinene include cationic polymerizable monomers, radical polymerizable monomers, coordination polymerizable monomers, and plant-derived terpenes.

  In the present invention, the cationically polymerizable monomer, radically polymerizable monomer, and coordination polymerizable monomer that are used when producing the β-pinene polymer are generally used conventionally. It is possible to use what is. Plant-derived terpenes can also be used as the polymerizable monomer in any of the cationic polymerization method, radical polymerization method and coordination polymerization method. Specifically, as the cationic polymerizable monomer, isobutylene, isoprene, butadiene, styrene, α-methylstyrene, p-methylstyrene, p-methoxystyrene, pt-butoxystyrene, indene, alkyl vinyl ether, norbornene Further, as the radical polymerizable monomer, methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate (Meth) acrylates such as 2-hydroxypropyl (meth) acrylate and glycidyl (meth) acrylate; nitrile group-containing vinyl monomers such as acrylonitrile and methacrylonitrile; amide group-containing vinyl monomers such as acrylamide and methacrylamide Chromatography; vinyl acetate, vinyl pivalate, vinyl esters such as vinyl benzoate, vinyl chloride, vinylidene chloride, maleic anhydride, maleic acid, fumaric acid, fumaric acid esters, may be mentioned maleimide. Examples of coordination polymerizable monomers include ethylene, propylene, 1-hexene, cyclopentene, norbornene, and plant-derived terpenes include myrcene, alloocimene, omesin, α-pinene. , Dipentene, limonene, α-ferrandrene, α-terpinene, γ-terpinene, 2-carene, 3-carene and the like. Among these, one or more types are appropriately selected and used according to the amount of β-pinene used. Since the β-pinene polymer is advantageously obtained by the cationic polymerization method, among the polymerizable monomers as described above, the cationic polymerizable monomer is particularly advantageously used.

  In the case where the copolymerizable monomer is copolymerized with β-pinene, the amount of copolymerization is preferably 0.001 to 50% by mass in the polymer, and more preferably 0.01 to 20% by mass. Preferably, 0.05-10 mass% is the most preferable. If the amount of copolymerization is too large, problems such as increased water absorption and reduced heat resistance are undesirable.

  On the other hand, a small amount of bifunctional or higher crosslinkable monomer (hereinafter referred to as a crosslinkable monomer) is copolymerized together with or in place of the above copolymerizable monomer. I can do it. Such a crosslinkable monomer is generally used as a branching agent or a crosslinking agent in the production of a polymer, but has a so-called long chain branching structure by reducing the amount used. A β-pinene polymer having a molecular weight that does not cause an insoluble part in an organic solvent is advantageously obtained. Specific examples of the crosslinkable monomer that can be used in the present invention include m-diisopropenylbenzene, p-diisopropenylbenzene, m-divinylbenzene, p-divinylbenzene, and 1,4-cyclohexanedimethanoldi. Bifunctional vinyl compounds such as vinyl ether and ethylene glycol divinyl ether can be mentioned, and among them, m-diisopropenylbenzene is preferably used from the viewpoints of economy and reactivity.

  When such a crosslinkable monomer is copolymerized with β-pinene (and a monomer copolymerizable with β-pinene), the copolymerization amount is 0.001 to 7% by mass in the polymer. Among them, 0.01 to 5% by mass is more preferable, and 0.05 to 4% by mass is most preferable. If the amount of copolymerization is too large, the resulting β-pinene polymer becomes gel and loses thermoplasticity, which is not preferable.

  By the way, the polymerization method of the β-pinene polymer used in the present invention is not particularly limited, and a known polymerization method suitable for each polymerizable monomer used can be appropriately selected. For example, any one of an anionic polymerization method, a cationic polymerization method, a radical polymerization method and a coordination polymerization method can be selected and used, but in general, a cationic polymerization method is adopted.

In addition, when obtaining the beta-pinene polymer used by this invention according to this cationic polymerization method, a well-known cationic polymerization catalyst is used suitably as the polymerization catalyst. Specifically, BF ₃ , BF ₃ OEt ₂ , BBr ₃ , BBr ₃ OEt ₂ , AlCl ₃ , AlBr ₃ , AlI ₃ , TiCl ₄ , TiBr ₄ , TiI ₄ , FeCl ₃ , FeCl ₂ , SnCl ₂ , SnCl ₄ , WCl ₆ , MoCl ₅ , SbCl ₅ , TeCl _2, etc., Group 3-16 group metal halogen compounds; HF, HCl, HBr, etc. hydrogen acids; H ₂ SO ₄ , H ₃ BO ₃ , HClO ₄ , oxo acids such as CH ₃ COOH, CH ₂ ClCOOH, CHCl ₂ COOH, CCl ₃ COOH, CF ₃ COOH, p-toluenesulfonic acid, CF ₃ SO ₃ H, H ₃ PO ₄ , P ₂ O ₅ , and these Polymer compounds such as ion exchange resins having a group; heteropolyacids such as phosphomolybdic acid and phosphotungstic acid; SiO ₂ , Al ₂ O ₃ , SiO ₂ -Al ₂ O ₃ , MgO-SiO ₂ , B ₂ O ₃ —Al ₂ O ₃ , WO ₃ —Al ₂ O ₃ , Zr ₂ O ₃ —SiO ₂ , sulfated zirconia, tungstate zirconia, zeolite exchanged with H ⁺ or rare earth elements, activated clay, acidic Examples thereof include solid acids such as solid phosphoric acid in which clay, γ-Al ₂ O ₃ , and P ₂ O ₅ are supported on diatomaceous earth.

These cationic polymerization catalysts may be used in combination, and other compounds may be added to the polymerization system. Such other compounds are compounds that can improve the activity of the catalyst, for example, by adding them. Examples of compounds that improve the activity of metal halide compounds as acidic compounds include MeLi, EtLi, BuLi, Et ₂ Mg, EtMgBr, Et ₃ Al, Et ₂ AlCl, EtAlCl ₂ , Et ₃ Al ₂ Cl ₃ , (I-Bu) ₃ Al, Et ₂ Al (OEt), metal alkyl compounds such as Me ₄ Sn, Et ₄ Sn, Bu ₄ Sn, Bu ₃ SnCl; 2-methoxy-2-phenylpropane, t-butanol, 1 , 4-bis (2-methoxy-2-propyl) benzene, 2-phenyl-2-propanol, and the like are exemplified as compounds used as a polymerization initiator in living cationic polymerization.

  Further, as a polymerization method of the β-pinene polymer used in the present invention, a solution polymerization method using a solvent may be used. The solvent that can be used varies depending on the polymerization method employed, and thus it is difficult to define it uniquely. For example, aromatic hydrocarbon solvents such as benzene, toluene, xylene, etc .; pentane, hexane, heptane, Aliphatic hydrocarbon solvents such as octane, cyclopentane, cyclohexane, methylcyclohexane, decalin; halogenated hydrocarbon solvents such as methyl chloride, methylene chloride, 1,2-dichloroethane, 1,1,2-trichloroethylene; esters, Examples thereof include oxygen-containing solvents such as ether. In view of reactivity, it is preferable to use an aromatic hydrocarbon solvent, an aliphatic hydrocarbon solvent, a halogenated hydrocarbon solvent, or the like. These solvents may be used alone or in combination of two or more.

  Although the usage-amount of such a solvent is not specifically limited, About 100-10000 mass parts normally with respect to 100 mass parts of monomers, such as (beta) -pinene, Preferably it is 150-5000 mass parts, More preferably, it is 200-3000. Part by mass. When the amount of the solvent is small, uniform mixing of the polymerization catalyst becomes difficult, so that the reaction becomes non-uniform, and a uniform polymer cannot be obtained, or the control of the reaction becomes difficult. On the other hand, when the amount of solvent is large, there is a problem that productivity is lowered.

  And when performing a polymerization reaction, -80 degreeC-100 degreeC is preferable normally, especially, -40 degreeC-80 degreeC is more preferable, and -20 degreeC-80 degreeC is the most preferable. If this reaction temperature is too low, the progress of the reaction is slow, and if it is too high, it becomes difficult to control the reaction and it is difficult to obtain reproducibility.

  Moreover, the reaction pressure for performing the polymerization reaction is not particularly limited, but is preferably 0.5 to 50 atm, and more preferably 0.7 to 10 atm. Usually, the polymerization reaction is performed at around 1 atm.

  Furthermore, the reaction time for conducting the polymerization reaction is not particularly limited, and the reaction time may be appropriately determined so that a β-pinene polymer is obtained in good yield according to conditions such as reaction temperature and reaction pressure. Good. Usually, it is about 0.01 to 24 hours, preferably 0.2 to 10 hours.

  By the way, the β-pinene polymer produced by the polymerization reaction can be obtained by, for example, reprecipitation, solvent removal under heating, solvent removal under reduced pressure, solvent removal with steam (steam stripping), etc. It can be separated and obtained from the reaction mixture by a normal operation in isolation from the solution.

The β-pinene polymer used in the present invention preferably has hydrogenated olefinic double bonds from the viewpoints of light resistance, impact resistance, heat resistance and the like. In general, the hydrogenation rate is preferably 90% or more, more preferably 95% or more, and most preferably 99% or more. In the present invention, the β-pinene polymer is hydrogenated and shows the hydrogenation rate ([number of hydrogenated olefinic double bonds] / [before hydrogenation]). The number of olefinic double bonds in the polymer]]) × 100 is desirably 95% or more. The hydrogenation rate of the unsaturated double bond (carbon-carbon double bond) in the hydrogenated polymer is determined by iodine titration method, infrared spectroscopic spectrum measurement, nuclear magnetic resonance spectrum ( ¹ H-NMR spectrum). It can be calculated using an analysis means such as measurement.

  Here, the method for hydrogenating the β-pinene polymer used in the present invention is not particularly limited, and a known method can be used. For example, homogeneous catalysts such as Wilkinson complex, cobalt acetate / triethylaluminum, nickel acetylacetonate / triisobutylaluminum, diatomaceous earth, magnesia, alumina, silica, alumina-magnesia, silica-magnesia, silica-alumina, synthetic zeolite, etc. A known method using a heterogeneous catalyst or the like in which a catalyst metal such as nickel, palladium, or platinum is supported on a support can be used.

  As a solvent that can be used for hydrogenation, any organic solvent that dissolves the polymer and is inert to the hydrogenation catalyst can be used. Specifically, aromatic hydrocarbon solvents such as benzene, toluene, xylene; aliphatic hydrocarbon solvents such as pentane, hexane, heptane, octane, cyclopentane, cyclohexane, methylcyclohexane, decalin; methyl chloride, methylene chloride Halogenated hydrocarbon solvents such as 1,2-dichloroethane, 1,1,2-trichloroethylene; oxygen-containing solvents such as esters and ethers. In view of reactivity, aromatic hydrocarbon solvents, aliphatic hydrocarbon solvents and the like are preferable. These solvents may be used alone or in combination of two or more.

Furthermore, although the reaction temperature of the hydrogenation reaction depends on the hydrogenation catalyst used and the hydrogen pressure, it is generally preferably about 20 ° C to 250 ° C, more preferably 25 ° C to 150 ° C, and even more preferably 40 ° C to 100 ° C. Is most preferred. If the reaction temperature is too low, the reaction will not proceed smoothly, and if the reaction temperature is too high, side reactions and molecular weight will tend to occur. The hydrogen pressure is preferably about normal pressure to about 200 kgf / cm ² , more preferably 5 to 100 kgf / cm ² . If the hydrogen pressure is too low, the reaction does not proceed smoothly, and if the hydrogen pressure is too high, there are restrictions on the apparatus.

  In addition, the density | concentration of (beta) -pinene polymer in such a hydrogenation reaction system is about 2 mass%-40 mass% normally, Preferably it is 3 mass%-30 mass%, More preferably, it is 5 mass%-20 % By mass. If the concentration of β-pinene polymer is low, productivity is likely to decrease, which is not preferable. Moreover, when the density | concentration of (beta) -pinene polymer is too high, the hydrogenated polymer may precipitate or the viscosity of a reaction mixture may become high and it may become difficult to perform stirring smoothly, and is unpreferable.

  The reaction time of the hydrogenation reaction depends on the hydrogenation catalyst used, the hydrogen pressure, and the reaction temperature, but is usually about 0.1 to 50 hours, preferably 0.2 to 20 hours, more preferably 0.5 hours to 10 hours will be employed.

  Furthermore, the β-pinene polymer after the hydrogenation reaction may be polymerized by, for example, reprecipitation, solvent removal under heating, solvent removal under reduced pressure, or solvent removal with steam (steam stripping). The product is separated and obtained from the reaction mixture by a normal operation for isolation from the solution.

  By the way, the molecular weight of the β-pinene polymer used in the present invention is about 30,000 to 1,000,000 in terms of weight average molecular weight from the viewpoint of the viscosity and melt viscosity of the polymerization solution, moldability, strength of the lens sheet, and heat resistance. It is preferably 40,000 to 500,000, more preferably 60,000 to 250,000, and most preferably 90,000 to 200,000. The weight average molecular weight of the polymer can be calculated using a known analysis method such as gel permeation chromatography (GPC) obtained in terms of polystyrene or static light scattering measurement (SLS).

  In addition, the glass transition temperature (Tg) of the β-pinene polymer used in the present invention is preferably higher from the usage environment of the lens sheet, and it is necessary to be 100 ° C. or higher in order to avoid adverse effects due to the heat of the light source. Among them, more preferably, it is 110 ° C. or higher. The upper limit of the glass transition temperature is not particularly defined, but is preferably about 200 ° C. This is because in an amorphous polymer such as the β-pinene polymer used in the present invention, if the glass transition temperature is too high, the entanglement of the polymer is reduced, and the molded product may become brittle.

  Further, the total light transmittance of the β-pinene polymer used in the present invention is preferably higher. Generally, it is preferably 80% or more in a flat specimen having a thickness of 3.2 mm, more preferably 85% or more. More preferably, 90% or more is most preferable.

  Furthermore, the β-pinene polymer used in the present invention preferably has a lower water absorption rate from the viewpoint of dimensional stability. The water absorption of the β-pinene polymer is preferably 0.2% or less as a saturated water absorption when placed in an atmosphere of 60 ° C. and 90% RH (relative humidity), more preferably 0.1% or less. In particular, 0.05% or less is most preferable. A β-pinene polymer giving such a water absorption rate is advantageously selected.

  Such a β-pinene polymer used in the present invention is characterized by a low specific gravity. Because the specific gravity is small, a lighter lens sheet can be obtained. Accordingly, the specific gravity of the β-pinene polymer used in the present invention needs to be 0.85 or more and less than 1.0, and more preferably 0.85 to 0.98. This is because it is difficult to obtain a polymer having a specific gravity smaller than 0.85, and when the specific gravity is 1.0 or more, the object of weight reduction cannot be sufficiently achieved.

  In addition, the β-pinene polymer used in the present invention preferably has an Abbe number at 25 ° C. of generally 55 or more, more preferably 58 or more, and most preferably 60 or more. . This is because a larger Abbe number is preferable from the viewpoint of color reproducibility.

  Further, since the β-pinene polymer used in the present invention has a large flexural modulus and hardly undergoes deformation due to bending, the lens sheet made of such β-pinene polymer can be made thinner. Have. In general, the flexural modulus of the β-pinene polymer is preferably 2500 MPa or more, more preferably 2700 MPa or more.

In addition, the β-pinene polymer used in the present invention is characterized by a small photoelastic coefficient. In particular, it has a feature that the photoelastic coefficient at a temperature equal to or higher than Tg is small. In addition, when the photoelastic coefficient at a temperature equal to or higher than Tg is large, there is a problem that optical distortion of a generally obtained molded product increases. Further, when trying to obtain a molded product having a small optical distortion, the range in which molding conditions can be selected is narrow, and the productivity is lowered. The photoelastic coefficient at a preferable temperature equal to or higher than Tg (for example, Tg + 20 ° C.) cannot be generally specified depending on the use, but is −3.0 × 10 ^{−10 to} 3.0 × 10 ⁻¹⁰ cm ² / dyn. and more preferably from ^{-1.0 × 10 -10 ~1.0 × 10 -10} cm 2 / dyn. By having a photoelastic coefficient in this range, a molded product having a small optical distortion can be obtained with high productivity.

  In addition, the β-pinene polymer for molding the lens sheet according to the present invention may contain various known compounding agents alone or in accordance with necessity within a range not impairing the object of the present invention. More than one species can be combined and mixed.

  Specific examples of such various compounding agents are not particularly limited as long as they are usually used in the resin industry. For example, antioxidants, ultraviolet absorbers, light stabilizers, near infrared absorption And compounding agents such as a colorant such as a colorant, a dye and a pigment, a lubricant, a plasticizer (softening agent), an antistatic agent, a fluorescent brightening agent, and a filler.

  Among them, examples of antioxidants include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, etc. Among them, phenolic antioxidants are preferable, and alkyl-substituted phenolic oxidations. Inhibitors are particularly preferred.

  As the phenolic antioxidant used here, specifically, conventionally known ones can be used. For example, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methyl Benzyl) -4-methylphenyl acrylate, 2,4-di-t-amyl-6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate, etc. Acrylate compounds such as those described in JP-A-179953 and JP-A-1-168463; octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2′-methylene -Bis (4-methyl-6-tert-butylphenol), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5- Limethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, tetrakis (methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxy) Phenylpropionate) methane [i.e. pentaerythrimethyl-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenylpropionate)], triethylene glycol bis (3- (3-t-butyl- Alkyl-substituted phenolic compounds such as 4-hydroxy-5-methylphenyl) propionate); 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bisoctylthio-1,3,5 -Triazine, 4-bisoctylthio-1,3,5-triazine, 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyani Roh) triazine group-containing phenol compounds such as 1,3,5-triazine.

The phosphorus antioxidant is not particularly limited as long as it is usually used in the general resin industry. For example, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris ( Nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl)- Monophosphite compounds such as 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tri Decylphosphite), 4,4′-isopropylidene-bis (phenyl-di-alkyl (C ₁₂ -C ₁₅ ) phosphite) And diphosphite-based compounds. Among these, monophosphite compounds are preferable, and tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite and the like are particularly preferable.

  Furthermore, examples of the sulfur antioxidant include dilauryl 3,3-thiodipropionate, dimyristyl 3,3′-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3. -Thiodipropionate, pentaerythritol-tetrakis- (β-lauryl-thiopropionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5 ] Undecane etc. can be mentioned.

  And these antioxidant can be used individually or in combination of 2 or more types, respectively. The amount of such an antioxidant is appropriately determined within a range that does not impair the purpose of the present invention, but is usually 0.001 with respect to 100 parts by mass of the β-pinene polymer. It is about -5 mass parts, Preferably it is the range of 0.01-1 mass part.

  Examples of the ultraviolet absorber include 2- (2-hydroxy-5-methylphenyl) 2H-benzotriazole, 2- (3-t-butyl-2-hydroxy-5-methylphenyl) -5-chloro- 2H-benzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) -5-chloro-2H-benzotriazole, 2- (3,5-di-t-butyl-2-hydroxyphenyl) ) -2H-benzotriazole, 5-chloro-2- (3,5-di-t-butyl-2-hydroxyphenyl) -2H-benzotriazole, 2- (3,5-di-t-amyl-2-) Benzotriazole ultraviolet absorbers such as hydroxyphenyl) -2H-benzotriazole; 4-t-butylphenyl-2-hydroxybenzoate, phenyl-2-hydroxy Zoate, 2,4-di-tert-butylphenyl-3,5-di-tert-butyl-4-hydroxybenzoate, hexadecyl-3,5-di-tert-butyl-4-hydroxybenzoate, 2- (2H- Benzotriazol-2-yl) -4-methyl-6- (3,4,5,6-tetrahydrophthalimidylmethyl) phenol, 2- (2-hydroxy-5-t-octylphenyl) -2H-benzotriazole Benzoate ultraviolet absorbers such as 2- (2-hydroxy-4-octylphenyl) -2H-benzotriazole; 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone -5-sulfonic acid trihydrate, 2-hydroxy-4-octyloxybenzophenone, 4 Benzophenone series such as dodecyloxy-2-hydroxybenzophenone, 4-benzyloxy-2-hydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,2′-dihydroxy-4,4′-dimethoxybenzophenone UV absorbers; acrylate UV absorbers such as ethyl-2-cyano-3,3-diphenyl acrylate, 2′-ethylhexyl-2-cyano-3,3-diphenyl acrylate; [2,2′-thiobis (4- t-octylphenolate)]-2-ethylhexylamine nickel and other metal complex ultraviolet absorbers and the like can be used.

  Furthermore, examples of the light stabilizer include 2,2,6,6-tetramethyl-4-piperidylbenzoate, bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, and bis (1,2 , 2,6,6-pentamethyl-4-piperidyl) -2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonate, 4- (3- (3,5 -Di-t-butyl-4-hydroxyphenyl) propionyloxy) -1- (2- (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl) -2,2, Examples thereof include hindered amine light stabilizers such as 6,6-tetramethylpiperidine.

  In addition, as the near-infrared absorber, for example, cyanine-based near-infrared absorber; pyrylium-based near-infrared absorber; squarylium-based near-infrared absorber; croconium-based near-infrared absorber; azurenium-based near-infrared absorber; phthalocyanine-based near Infrared absorbers; dithiol metal complex-based near infrared absorbers; naphthoquinone near infrared absorbers; anthraquinone near infrared absorbers; indophenol near infrared absorbers; As commercially available near infrared absorbers, SIR-103, SIR-114, SIR-128, SIR-130, SIR-132, SIR-152, SIR-159, SIR-162 (above, Mitsui Toatsu Dye Co., Ltd.) Company-made), Kayasorb IR-750, Kayasorb IRG-002, Kayasorb IRG-003, Kayasorb IR-820B, Kayasorb IRG-022, Kayasorb IRG-023, Kayasorb CY9, Kayasorb CY9, , Manufactured by Nippon Kayaku Co., Ltd.).

  The dye is not particularly limited as long as it is uniformly dispersed / dissolved in the β-pinene polymer to be used, but has excellent compatibility with the β-pinene polymer used in the present invention. Therefore, oil-soluble dyes (various CI solvent dyes) are widely used. Specific examples of the oil-soluble dye include “Color Index” published in The Society of Dyers and Colorists, Vol. 3. Various C.I. I. Solvent dyes may be mentioned.

  Further, among the pigments, organic pigments include, for example, diarylide pigments such as Pigment Red 38; azo lake pigments such as Pigment Red 48: 2, Pigment Red 53, Pigment Red 57: 1; Pigment Red 144, Pigment Red 166, Pigment Red 220, Pigment Red 221, Pigment Red 248, and other condensed azo pigments; Pigment Red 171, Pigment Red 175, Pigment Red 176, Pigment Red 185, Pigment Red 208, and other benzimidazolone pigments; Quinacridone pigments such as Pigment Red 149, Pigment Red 178, and Pigment Red 179; and anthraquinone pigments such as Pigment Red 177. Examples of inorganic pigments include titanium oxide, carbon black, red pepper, chrome red, molybdenum red, resurge, and iron oxide.

  When coloring is required for the lens sheet of the present invention, any of the dyes and pigments described above can be used within the scope of the object of the present invention and is not particularly limited. In the case of a lens sheet in which various optical characteristics are a problem, coloring with a dye is preferable. In addition, the ultraviolet absorber may show a yellow to red color visually, and the near infrared absorber may show a black color visually, so there is no need to use these and dyes strictly, Moreover, there is no problem even if they are used in combination.

  As the lubricant, organic compounds such as aliphatic alcohol esters, polyhydric alcohol esters or partial esters, inorganic fine particles, and the like can be used. Here, examples of the organic compound include glycerol monostearate, glycerol monolaurate, glycerol distearate, pentaerythritol monostearate, pentaerythritol distearate, pentaerythritol tristearate, and the like.

  Further, as other lubricants, generally inorganic fine particles can be used. Here, the inorganic fine particles include oxides, sulfides, hydroxides, nitrides, halides, carbonates, sulfates, acetic acids of the elements of Groups 1, 2, 4, and 6-14 of the periodic table. Examples thereof include fine particles of salts, phosphates, phosphites, organic carboxylates, silicates, titanates, borates and their hydrates, composite compounds centered on them, natural compounds, and the like.

  Examples of the plasticizer include tricresyl phosphate, trixylenyl phosphate, triphenyl phosphate, triethylphenyl phosphate, diphenyl cresyl phosphate, monophenyl dicresyl phosphate, diphenyl monoxylenyl phosphate. Phosphate triester plasticizers such as phosphate, monophenyldixylenyl phosphate, tributyl phosphate, triethyl phosphate; dimethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-n-octyl phthalate, di-phthalate Phthalate plasticizers such as 2-ethylhexyl, diisononyl phthalate, octyldecyl phthalate, and butylbenzyl phthalate; fatty acid monobasic acids such as butyl oleate and glycerol monooleate Plasticizers; dihydric alcohol ester plasticizers; oxyester plasticizers and the like can be used. Of these, phosphate triester plasticizers are preferred, and tricresyl phosphate and trixylenyl phosphate are preferred. Particularly preferred.

Furthermore, as specific examples of other plasticizers, squalane (C ₃₀ H ₆₂ , Mw = 422.8), liquid paraffin (white oil, ISO VG10, ISO VG15, ISO VG32, ISO VG32 as defined in JIS-K-2231) VG68, ISO VG100, ISO VG8 and ISO VG21), polyisobutene, hydrogenated polybutadiene, hydrogenated polyisoprene, and the like. Among these, squalane, liquid paraffin, and polyisobutene are preferably used.

  Furthermore, examples of the antistatic agent include long-chain alkyl alcohols such as stearyl alcohol and behenyl alcohol, fatty acid esters of polyhydric alcohols such as glycerin monostearate and pentaerythritol monostearate, and stearyl alcohol and behenyl alcohol. Particularly preferred.

  These compounding agents can be used alone or in admixture of two or more, and the mixing ratio is appropriately selected within a range not impairing the object of the present invention. Further, the amount of each compounding agent described above is also appropriately selected within a range that does not impair the object of the present invention, but for each compounding agent, it is usually 0 with respect to 100 parts by mass of the β-pinene polymer. About 0.001 to 5 parts by mass, preferably 0.01 to 1 part by mass.

  The β-pinene polymer for molding the lens sheet according to the present invention as described above can be blended with other polymer components as necessary within a range not impairing the object of the present invention. . Examples of the other polymer include rubbery polymers, specifically, diene rubbers such as natural rubber, polybutadiene rubber, polyisoprene rubber, acrylonitrile / butadiene copolymer rubber; styrene / butadiene copolymer. Rubber, styrene / isoprene copolymer rubber, styrene / butadiene / isoprene terpolymer rubber; hydrogenated diene rubber; ethylene / α-olefin copolymer such as ethylene / propylene copolymer, propylene / other Saturated polyolefin rubbers such as α-olefin copolymers; α-olefins such as ethylene / propylene / diene copolymers, α-olefin / diene copolymers, isobutylene / isoprene copolymers, and isobutylene / diene copolymers・ Diene polymer rubber; urethane rubber, silicone rubber, polyester Special rubbers such as tellurium rubber, acrylic rubber, propylene oxide rubber and ethylene / acrylic rubber; thermoplastic elastomers such as styrene / butadiene / styrene block copolymer rubber and styrene / isoprene / styrene block copolymer rubber; heat of hydrogenation Mention may be made of plastic elastomers; urethane thermoplastic elastomers; polyamide thermoplastic elastomers; 1,2-polybutadiene thermoplastic elastomers. Further, the blending amount is appropriately selected within a range that does not impair the object of the present invention. It is the range of -20 mass parts.

  In order to form a lens sheet according to the present invention using such a β-pinene polymer, known methods such as a casting method, an injection molding method, a hot press molding method, an extrusion molding method, and a cutting method are used. According to the method, simultaneously with the molding of the transparent substrate made of β-pinene polymer, a desired lens portion is formed integrally with the substrate, or an active energy ray-curable resin is used to form a β-pinene polymer. Ordinarily used methods such as a method of integrally forming a desired lens part on a transparent base material made of a united material are appropriately adopted, thereby easily producing a target lens sheet. I can do it. In addition, when employ | adopting the method using an active energy ray hardening-type resin, it shape | molds previously which consists of (beta) -pinene polymer whose specific gravity is 0.85 or more and less than 1.0 and whose glass transition temperature is 100 degreeC or more. A target lens portion is integrally formed on the thus-formed substrate by a known active energy ray-curable resin.

  Here, the lens sheet referred to in the present invention refers to the direction of the light beam applied to the sheet in the lens unit composed of a lens group composed of one or more lens shapes formed on at least one of the sheet main surfaces. And has functions such as condensing, refraction, reflection, and dispersion. Such lens sheets generally include what are called prism sheets, Fresnel lens sheets, lenticular lens sheets, microlens array sheets, and the like.

  In addition, the lens shape refers to a shape in which a cross-sectional shape perpendicular to at least one sheet main surface includes a straight line, a curve, or a combination thereof that is not parallel to the sheet main surface, and examples of the cross-sectional shape include , A part of a polygon, an arc, an elliptical arc, an asymptotic line, a sine curve, a part of a polygon with a smooth top, and the like.

  Furthermore, examples of the lens shape include stripe shapes and dot shapes. Among them, in the case of a stripe shape, it is easy to provide a function of efficiently changing the light direction in one direction perpendicular to the longitudinal direction of the stripe. The ridge line that forms the top of the stripe is usually a straight line or a curve that is substantially parallel to the main surface of the sheet. The shape in the case where the stripe lens shape is observed from the normal direction of the sheet main surface is a quadrilateral shape and is usually rectangular, and the side in the longitudinal direction usually covers substantially the entire surface of the sheet. . In the case of dots, it is easy to provide a function of efficiently changing the light direction in multiple directions or all directions. The shape when the dot-like lens shape is observed from the normal direction of the sheet main surface is a shape including a straight line, a curved line, and a combination thereof.

  These lens shapes having the same or different shapes are regularly arranged in a plurality, so that the function of changing the light beam direction in the sheet surface can be made uniform. Further, this lens shape may be formed on both surfaces of the sheet main surface, and the lens shape, the arrangement rule, etc. on both surfaces may be the same or different. Further, the arrangement period of the lens shape is preferably about 10 μm to 1000 μm, although it depends on the size of the main surface of the sheet. When the sheet main surface is small, it is preferable to reduce the arrangement period in many applications.

  In the present invention, a lens sheet according to the present invention is used on an illumination device arranged on a light transmission path, as shown in the above-mentioned patent documents. By disposing the transmissive display element, an image display device is configured. Here, the image display device is intended to mean a display module in which a lighting device and a display element are combined, and a device having at least an image display function such as a television or a personal computer monitor using the display module. A typical example of the transmissive display element used therein is a well-known liquid crystal panel.

  Hereinafter, some examples of the present invention will be shown and the present invention will be more specifically clarified, but the present invention is not limited by the description of such examples. It goes without saying. In addition to the following examples, the present invention can be subjected to various changes, corrections, improvements and the like based on the knowledge of those skilled in the art without departing from the spirit of the present invention. Should be understood.

(1) Synthesis of β-pinene polymer hydrogenated product About a well-dried glass flask with a cock, the inside was sufficiently purged with nitrogen, and then dehydrated N-hexane: 184 parts by mass, and dehydrated Methylene chloride: 210 parts by mass and dehydrated diethyl ether: 0.5 parts by mass were added and cooled to -78 ° C. While stirring the mixture at -78 ° C, hexane solution of ethylaluminum dichloride (concentration: 1.0 mol / L): 7.2 parts by mass was further added. Next, in a state where the inside of the flask was kept at −78 ° C., when 3.0 parts by mass of a hexane solution of p-dicumulyl chloride (concentration: 0.1 mol / L) was added, the color changed to red amber. Thereafter, 60 parts by mass of β-pinene that was immediately purified by distillation was added to the flask over 1 hour. The solution gradually became dark blue and the viscosity of the solution increased. After the addition of β-pinene, 30 parts by mass of methanol was added to terminate the reaction. In the flask, an aqueous solution obtained by adding 5 parts by mass of citric acid to 100 parts by mass of distilled water is added and stirred for 5 minutes. Then, the aqueous layer is extracted, and the aqueous layer becomes neutral by adding distilled water. Until the aluminum compound was removed. The obtained organic layer was reprecipitated in a mixed solvent of methanol / acetone (50/50 vol%): 5000 parts by mass and then sufficiently dried to obtain 60 parts by mass of β-pinene polymer (A1). . The obtained β-pinene polymer (A1) had a weight average molecular weight of 116,000, a number average molecular weight of 51,000, and a glass transition temperature of 95 ° C.

By adding 70 parts by mass of cyclohexane and 30 parts by mass of the β-pinene polymer (A1) obtained as described above to a pressure vessel equipped with a stirrer substituted with nitrogen, and stirring the mixture, a β-pinene polymer ( A1) was completely dissolved. Next, 5% palladium-supported alumina (manufactured by NE ChemCat) as a hydrogenation catalyst: 30 parts by mass was added and sufficiently dispersed by stirring, and then the inside of the pressure vessel was sufficiently replaced with hydrogen. While stirring at 1000 rpm, the mixture was reacted at 100 ° C. and hydrogen pressure of 40 kgf / cm ² for 6 hours, and then returned to normal pressure. The reaction solution was diluted by adding 200 parts by mass of cyclohexane, filtered through a 0.5 μm Teflon (registered trademark) filter to separate and remove the catalyst, and then a mixed solvent of methanol / acetone (50/50 vol%): 5000 After re-precipitation in parts by mass, it was sufficiently dried to obtain 29 parts by mass of β-pinene polymer hydrogenated product (H1). When the hydrogenation rate of the obtained β-pinene polymer hydrogenated product (H1) was determined from ¹ H-NMR, it was 99.9%, the weight average molecular weight was 112,000, and the number average molecular weight was 50,800. The glass transition temperature was 130 ° C. and the specific gravity was 0.930.

  Thereafter, 0.1 part of 2- (5-methyl-2hydroxyphenyl) benzotriazole, which is an ultraviolet absorber, is added to 100 parts by mass of the thus obtained high molecular weight β-pinene polymer hydrogenated product (H1). After mixing a mass part and 0.1 mass part of Irganox 1010 (manufactured by Ciba Specialty Chemicals Co., Ltd.) which is a phenolic antioxidant, using a Henschel mixer, melt-kneading using an extruder, A pellet-like β-pinene polymer hydrogenated composition (M1) was obtained.

(2) Production of film used in Example 1 The β-pinene polymer hydrogenated composition (M1) obtained above (M1) (glass transition temperature: 130 ° C.) was pelleted using a hot air drier. Drying was performed at 4 ° C. for 4 hours. This pellet was melt-extruded at 260 ° C. using a twin screw extruder having a screw diameter of 20 mm and a chrome-plated coat hanger die having a width of 500 mm, and then the extruded sheet-like β-pinene polymer hydrogen was extruded. The additive composition (M1) was cooled by passing through three cooling rolls (diameter: 100 mm, roll temperature: 120 ° C.) to obtain an extruded film having a width of about 400 mm and a thickness of 100 μm. Next, with respect to the obtained film, under the conditions of illuminance: 5.9 mW / cm ² (172 nm), irradiation amount: 354 mJ / m ² (distance from irradiation window: 2.3 mm, time: 60 seconds). Excimer treatment was performed to obtain a surface-treated film (F1).

(3) Production of Comparative Example 1 Film Used Acrylic resin (Parapet EH1000 manufactured by Kuraray Co., Ltd., glass transition temperature: 100 ° C.) was dried at 80 ° C. for 4 hours using a hot air dryer. . This pellet was melt-extruded at 260 ° C. using the same apparatus as in (2) above, and then the extruded sheet-like acrylic resin was cooled by three cooling rolls (diameter: 100 mm, roll temperature: 90 ° C.) And cooled to obtain an extruded film having a width of about 400 mm and a thickness of 100 μm. Next, the excimer was applied to the obtained film under the conditions of illuminance: 5.9 mW / cm ² (172 nm), irradiation amount: 354 mJ / m ² (distance from irradiation window: 2.3 mm, time: 60 seconds). The surface treatment film (F2) was obtained by performing the treatment.

(4) Production of film used in Comparative Example 2 Using pellets of alicyclic polyolefin resin (ZEONOR 1060R manufactured by Nippon Zeon Co., Ltd., glass transition temperature: 100 ° C.) using a hot air dryer at 80 ° C. for 4 hours. Was dried. This pellet was melt-extruded at 260 ° C. using the same apparatus as in (2) above, and then the extruded sheet-like alicyclic polyolefin-based resin was cooled to three cooling rolls (diameter: 100 mm, roll temperature). : 90 ° C.) to obtain an extruded film having a width of about 400 mm and a thickness of 100 μm. Next, the excimer was applied to the obtained film under the conditions of illuminance: 5.9 mW / cm ² (172 nm), irradiation amount: 354 mJ / m ² (distance from irradiation window: 2.3 mm, time: 60 seconds). The surface treatment film (F3) was obtained by performing the treatment.

  In addition, about the material obtained at each above-mentioned process, and the material manufactured at the following process, the physical-property measurement was performed as follows.

-Molecular weight-
The number average molecular weight and the weight average molecular weight are both determined in terms of polystyrene based on measurement by gel permeation chromatography (GPC). Here, HLC-8020 (product number) manufactured by Tosoh Co., Ltd. is used as the GPC device, and TSKgel / GMH-M manufactured by Tosoh Co., Ltd. and one G2000H are connected in series as the column. Using.

-Hydrogenation rate-
^{From the 1} H-NMR spectrum, the hydrogenation rate {([number of hydrogenated olefinic double bonds] / [hydrogen] is determined by the reduction rate (%) of olefinic double bond protons (4 to 6 ppm) of the raw material resin. The number of olefinic double bonds in the polymer before addition]) × 100 (%)} was determined.

-Glass transition temperature (Tg)-
It measured by the differential scanning calorimetry (DSC) using the sample which fully dried and removed the solvent. First, a sample is heated from 25 ° C. to 200 ° C. at a rate of temperature increase of 10 ° C./min under a stream of nitrogen of 100 ml / min to obtain a DSC curve. Next, using the obtained DSC curve, as shown in FIG. 1, a parallel line E passing through the intersection of the center tangent B and the base line C before the transition and parallel to the temperature axis, and the center tangent B A parallel line F passing through the intersection of the base line D after the transition and parallel to the temperature axis is drawn. In this specification, the temperature A at the intersection of the parallel line G that bisects the two parallel lines E and F and the DSC curve is defined as the glass transition temperature (Tg). In addition, here, DSC30 (product number) manufactured by METTLER TOLEDO Co., Ltd. was used as a measuring device.

-Water absorption rate-
A press-molded plate having a length of 140 mm, a width of 60 mm, and a thickness of 0.8 mm was placed in a 60 ° C., 90% RH atmosphere for 10 days, and the ratio of the weight increased from the initial weight was The water absorption rate was used. The arithmetic expression is as follows.
Water absorption (%) = Weight increase x 100 / initial weight

-Refractive index (nD)-
It measured at 25 degreeC based on JIS-K-7142 using RX-2000 (product number) made from Atago Co., Ltd ..

-Abbe number-
Measurement was performed at 25 ° C. using an Abbe refractometer DR-M2 (product number) manufactured by Atago Co., Ltd. And it evaluated according to the following criteria.
○: Abbe number ≧ 57
Δ: 57> Abbe number ≧ 55
×: 55> Abbe number

-Flexural modulus-
Using an autograph (manufactured by Shimadzu Corporation), the flexural modulus at 23 ° C. was measured according to JIS-K-7171 and evaluated according to the following criteria.
○: Flexural modulus is 2500 MPa or more ×: Flexural modulus is less than 2500 MPa

-Specific gravity-
It measured according to A method of JIS-K-7112: 1999. Judgment criteria are as follows.
○: Specific gravity <1.0
Δ: 1.0 ≦ specific gravity <1.1
×: 1.1 ≦ specific gravity

-Photoelastic coefficient-
Thickness: A 200 μm film was annealed overnight at a temperature 20 ° C. lower than Tg, and then subjected to a tensile stress in the major axis direction at a temperature 20 ° C. higher than Tg. It was measured with M220 (manufactured by JASCO Corporation), and the photoelastic coefficient was calculated from the amount of change in retardation with respect to stress.

-Light resistance-
A press-molded plate with a thickness of 1.0 mm is subjected to an accelerated exposure test for 100 hours in accordance with ASTM-G53, and the yellowing degree (ΔYI) before and after the test of YI (yellow index) is determined. It was measured. Here, an ultraviolet exposure tester (ATLAS-UVCON manufactured by Toyo Seiki Seisakusho Co., Ltd.) was used. YI was measured according to JIS-K-7103. And it evaluated according to the following criteria.
ΔYI = (YI after 100 hours of UV exposure) − (YI before UV exposure)
○: ΔYI ≦ 1 Long-term light resistance is very good ×: 1 <ΔYI Long-term light resistance is poor

Example 1
A commercially available ultraviolet curable resin liquid (UVX 4332 manufactured by Toagosei Co., Ltd., refractive index: 1.52) was injected into a lens mold having a prism pattern with a lens pitch of 50 μm and an apex angle of 90 °. Further, the 12-inch surface treatment film (F1) obtained above is superimposed on the lens mold, and then irradiated with ultraviolet rays from the surface treatment film side using an ultraviolet lamp disposed above. After the ultraviolet curable resin liquid was polymerized and cured, it was peeled from the lens mold to obtain a lens sheet (L1) in which a large number of prismatic protrusions were integrally formed on one side. The evaluation results of the lens sheet (L1) thus obtained are shown in Table 1 below.

  In addition, on the exit surface of the direct type diffusion plate, a diffusion sheet (Opulse # 125KBS21, Haze: 89.5%, manufactured by Ewa Co., Ltd.) was placed, and the lens sheet obtained above was placed, Configured the backlight. And about this backlight, from 500mm right above a backlight unit, using a color luminance meter (BM-7 manufactured by Topcon Co., Ltd.), the luminance is measured while tilting the backlight by 5 degrees, and the viewing angle characteristics are measured. Evaluation was performed. The result is shown by a solid line in FIG. The front luminance increase rate at this time was 1.45 times, which was a favorable front luminance. In addition, the viewing angle characteristic of the brightness | luminance shown by the dotted line in the figure was measured about the backlight which does not use a lens sheet.

-Comparative Example 1-
A lens sheet (L2) was obtained in the same manner as in Example 1 except that the surface treatment film (F2) was used instead of the surface treatment film (F1). The evaluation results of the obtained lens sheet (L2) are shown in Table 1 below.

-Comparative Example 2-
A lens sheet (L3) was obtained in the same manner as in Example 1 except that the surface treatment film (F3) was used instead of the surface treatment film (F1). The evaluation results of the obtained lens sheet (L3) are shown in Table 1 below.

  From the results in Table 1, it can be seen that the lens sheet of Example 1 according to the present invention is superior in heat resistance and lighter than a lens sheet using other resins. Moreover, since the lens sheet of this invention has low water absorption compared with the lens sheet which consists of acrylic resins, it is recognized that the deformation | transformation by water absorption is small.

  Further, from the results in Table 1, the lens sheet of Example 1 according to the present invention has a small proportion of tertiary carbon and a small change in YI value before and after the test, compared with a lens sheet made of alicyclic polyolefin resin. It is recognized that In addition, although an alicyclic polyolefin-type resin has a low bending elastic modulus and is easy to bend, the lens sheet of (beta) -pinene polymer hydrogenated substance has a high bending elastic modulus, and it turns out that it is hard to bend.

  Furthermore, since the lens sheet according to the present invention has a small photoelastic coefficient, it has a small optical distortion and a large Abbe number, so that it can be obtained as a lens sheet with a small chromatic aberration.

It is explanatory drawing which shows the method of calculating | requiring the glass transition temperature in an Example from a DSC curve. 6 is a graph showing the evaluation results of viewing angle characteristics obtained in Example 1.

Claims (3)

  A lens portion composed of one or a plurality of lens groups is provided on at least one surface of a transparent substrate composed of a β-pinene polymer having a specific gravity of 0.85 or more and less than 1.0 and a glass transition temperature of 100 ° C. or more. A lens sheet characterized by being formed.   The β-pinene polymer is hydrogenated, and ([number of olefinic double bonds hydrogenated] / [number of olefinic double bonds in the polymer before hydrogenation] The lens sheet according to claim 1, wherein a value of × 100 is 95% or more. An image display device comprising the lens sheet according to claim 1.

Images