WO2007145217A1 - Luminance improving film, method for producing the same, and liquid crystal display - Google Patents

Luminance improving film, method for producing the same, and liquid crystal display Download PDF

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Publication number
WO2007145217A1
WO2007145217A1 PCT/JP2007/061827 JP2007061827W WO2007145217A1 WO 2007145217 A1 WO2007145217 A1 WO 2007145217A1 JP 2007061827 W JP2007061827 W JP 2007061827W WO 2007145217 A1 WO2007145217 A1 WO 2007145217A1
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WIPO (PCT)
Prior art keywords
film
liquid crystal
brightness enhancement
layer
light
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PCT/JP2007/061827
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French (fr)
Japanese (ja)
Inventor
Hitoshi Ooishi
Koya Kawabata
Original Assignee
Zeon Corporation
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Zeon Corporation filed Critical Zeon Corporation
Priority to JP2008521218A priority Critical patent/JPWO2007145217A1/en
Publication of WO2007145217A1 publication Critical patent/WO2007145217A1/en

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B5/00—Optical elements other than lenses
    • G02B5/30—Polarising elements
    • G02B5/3016—Polarising elements involving passive liquid crystal elements
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/13—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  based on liquid crystals, e.g. single liquid crystal display cells
    • G02F1/133—Constructional arrangements; Operation of liquid crystal cells; Circuit arrangements
    • G02F1/1333—Constructional arrangements; Manufacturing methods
    • G02F1/1335—Structural association of cells with optical devices, e.g. polarisers or reflectors
    • G02F1/13363—Birefringent elements, e.g. for optical compensation
    • G02F1/133634—Birefringent elements, e.g. for optical compensation the refractive index Nz perpendicular to the element surface being different from in-plane refractive indices Nx and Ny, e.g. biaxial or with normal optical axis

Definitions

  • Brightness enhancement film method for producing the same, and liquid crystal display device
  • the present invention has a function of polarizing light from a light source, and is used in a display device such as a liquid crystal display device, an organic EL display device, or a plasma display panel in combination with another optical film.
  • the present invention relates to a brightness enhancement film capable of realizing a bright display by improving light use efficiency in a display device, a manufacturing method thereof, and a liquid crystal display device.
  • a polarizing plate having a polarizing plate and a brightness enhancement film bonded to each other is provided on the back side of the liquid crystal cell.
  • the brightness enhancement film shows the characteristic that when natural light is incident due to a knock light such as a liquid crystal display device or reflection of back side force, it reflects linearly polarized light with a predetermined polarization axis or circularly polarized light in a predetermined direction and transmits other light.
  • a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a knock light to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting through light other than the predetermined polarization state. Is done.
  • the light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state.
  • the brightness can be improved by increasing the amount of light transmitted through the brightness enhancement film and increasing the amount of light that can be used for liquid crystal display image display etc. by supplying polarized light that is difficult to be absorbed by the polarizer.
  • the brightness enhancement film transmits a linearly polarized light having a predetermined polarization axis and reflects other light, such as a dielectric multilayer thin film or a multilayer laminate of thin film films having different refractive index anisotropies. Reflects either left-handed or right-handed circularly polarized light and transmits other light, such as those exhibiting properties, such as those in which a cholesteric liquid crystal polymer oriented film or its oriented liquid crystal layer is supported on a film substrate Proposals have been made for characteristics.
  • a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer
  • it can be incident on a polarizer as it is, but the circularly polarized light is applied to a retardation plate from the viewpoint of suppressing absorption loss.
  • the light is linearly polarized and incident on the polarizing plate.
  • a 1Z4 wavelength plate as the difference plate, circularly polarized light can be converted to linearly polarized light.
  • brightness enhancement films that transmit circularly polarized light such as cholesteric liquid crystal layers, use a cholesteric liquid crystal layer and a 1Z4 wave plate laminated via other adhesive means, and various proposals have been made. ing.
  • Patent Document 1 Japanese Patent No. 3373374
  • Patent Document 2 Japanese Patent Application Laid-Open No. 11 00 2722
  • a brightness enhancement film having a laminate strength bonded through an excellent adhesive layer.
  • Patent Document 3 Japanese Patent Application Laid-Open No. 2004-191803 is formed by stacking layers of a cholesteric liquid crystal film, a liquid crystal alignment film, and a retardation plate via an adhesion means, and any one of the adhesion means.
  • a brightness enhancement film is disclosed in which at least one is an adhesive layer and the storage modulus at 23 ° C. is from 0.5 to: LOOMPa.
  • a display device such as a liquid crystal display device in which the brightness enhancement film is used is used under an environment where an unexpected external force is applied or a temperature change is severe.
  • an unexpected external force is applied or a temperature change is severe.
  • Liquid crystal display devices used in car navigation systems are used in vehicles where the temperature changes drastically throughout the day and night. For this reason, it is important to have sufficient physical durability against external forces and temperature changes.
  • the brightness enhancement film is punched into a desired size according to the display device of each application destination. Since it is a laminate, it is important that the workability during punching is good.
  • display devices such as liquid crystal display devices have been used in large quantities for various purposes in recent years. Therefore, it is important to reduce manufacturing costs, particularly in terms of materials used.
  • the product called brightness enhancement film has high transparency and improved light utilization efficiency.
  • Conditions for improving physical durability, punching workability, and reducing manufacturing costs are important conditions that must be realized at the same time without sacrificing other conditions.
  • the polarizing element disclosed in Patent Document 1 is obtained by laminating a polarization separation film and a 1Z4 wavelength plate via an adhesive layer. Therefore, at the time of punching, an adhesive component adheres to the punching blade or an adhesive layer is stretched, the processing efficiency is lowered, and the shape characteristics of the punched product become insufficient.
  • Patent Document 2 in addition to the problem in processability as in Patent Document 1, since a cholesteric liquid crystal polymer is used for the polarization separation film, it is difficult to improve the orientation. It is difficult to further improve the polarization efficiency.
  • Patent Document 3 three types of films are integrated by an adhesive means, and the pressure-sensitive adhesive layer and the adhesive layer are used separately in order to improve the crack resistance of the laminate. is doing. That is, a laminated structure of a cholesteric liquid crystal film, an adhesive layer, a liquid crystal alignment film, an adhesive layer, and a retardation plate is employed. That is, by using a pressure-sensitive adhesive and an adhesive in combination, stress on each film is relaxed and crack resistance is improved.
  • the brightness enhancement film of Patent Document 3 is the same as Patent Documents 1 and 2 in that an adhesive is used. This brightness enhancement film has an adhesion to a punching blade. There are also problems to be solved, such as adhesive adhesion and adhesive layer elongation. In addition, since it has a five-layer structure, the manufacturing process becomes complicated and the yield decreases. Furthermore, since the brightness enhancement film of Patent Document 3 includes a liquid crystal alignment film as an essential element, the configuration is complicated.
  • the present invention has been made in view of the above-mentioned conventional problems, and its problems are improved brightness, improved transparency, improved punchability, and reduced product cost. It is to provide a rumm and a manufacturing method thereof.
  • the brightness enhancement film of the present invention is a retardation film obtained by stretching a resin film including a styrene-based resin layer, and a polarizing film including a resin layer having cholesteric regularity. It is characterized by comprising a separation film, and an adhesive layer between the retardation film and the polarization separation film, which also has a compositional force with a shear storage modulus of 1 to 500 MPa at a temperature of 23 ° C.
  • the film is incident on the brightness enhancement film obliquely when the brightness enhancement film of the present invention is mounted on a liquid crystal display device.
  • the emitted light can be effectively extracted as the desired polarized light.
  • a retardation film formed by stretching a resin film including a styrene-based resin layer using an adhesive layer composed of a composition having a shear storage modulus of 1 to 500 MPa at a temperature of 23 ° C, and polarization separation Since the film is bonded together and good adhesion and stress relaxation are realized at the same time, the punching workability of the film can be kept within a good range.
  • the adhesive means an adhesive substance that does not exhibit tackiness at room temperature (20 ⁇ 15 ° C: JIS standard), and the adhesive refers to an adhesive substance that exhibits tackiness at room temperature. Means. Therefore, the adhesive layer does not exhibit tackiness at room temperature.
  • “not showing tackiness” means showing tackiness of less than 2 in ball number as measured by JIS Z0237 tilted ball tack measurement.
  • the adhesive layer preferably has a thickness of 2 ⁇ -50 / ⁇ m. Since the adhesive used in the present invention is a so-called hot melt type adhesive that does not have tackiness at room temperature, When the thickness is less than 2 m, the adhesiveness at room temperature becomes insufficient, and the stress relaxation property between the laminated films due to the interposition of the adhesive may be insufficient. On the other hand, if it exceeds 50 m, it becomes difficult to apply the adhesive, and poor appearance of the laminate tends to be induced.
  • the resin layer having cholesteric regularity is a non-liquid crystalline resin layer formed by polymerizing a liquid crystal composition containing a polymerizable liquid crystal compound.
  • the orientation of the resin layer can be enhanced.
  • Rth ⁇ (nx + ny) Z2—nz ⁇ X d (where nx is a direction perpendicular to the thickness direction and giving the maximum refractive index) Ny is the refractive index in the direction perpendicular to the thickness direction and perpendicular to nx, nz is the refractive index in the thickness direction, and d is the film thickness.
  • Decision Rth force 20 to 1 100 Onm is preferable. Powerful Rth can be set easily because the retardation film uses styrene-based resin as a material. Retardation films set at a high Rth can be obtained at low cost and can replace the performance of more expensive liquid crystal alignment films.
  • the method for producing a brightness enhancement film of the present invention includes a step of bonding the polarization separation film and the retardation film through the adhesive layer, and the bonding step V, The polarized light separating film and the retardation film are bonded together by heating in the range of 40 ° C to 110 ° C.
  • the retardation film as a component thereof has a styrene-based resin layer, so that the dimensional stability against heat is enhanced, and as a result, in the above temperature range. Thermal bonding is possible.
  • This hot melt adhesive layer maintains good punching processability as described above.
  • a liquid crystal display device of the present invention includes any one of the brightness enhancement films described above.
  • the brightness enhancement film according to the present invention has good transparency and punching workability, and can reduce the product cost. By using it in various display devices, the brightness of the display device can be reduced. And the cost of the display device can be reduced.
  • FIG. 1 is an explanatory view showing the structure and function of a polarization separating film constituting the brightness enhancement film according to the present invention.
  • FIG. 2 is an exploded perspective view showing the configuration of the liquid crystal display device of the present invention.
  • the brightness enhancement film according to the present invention includes a retardation film formed by stretching a resin film including a styrene-based resin layer, a polarizing separation film including a resin layer having cholesteric regularity, And an adhesive layer made of a composition having a shear storage modulus of 1 to 500 MPa at a temperature of 23 ° C. is included between the retardation film and the polarization separation film.
  • a conventionally known styrene-based resin multilayer film can be used as the “film containing a styrene-based resin layer” constituting the retardation film in the present invention.
  • a multilayer film formed by laminating a film (b layer) made of another thermoplastic resin on both sides of a film (a layer) made of styrene-based resin can be exemplified.
  • the styrene-based resin constituting the layer a is a resin having a styrene structure as a part or all of the repeating units, specifically, polystyrene, styrene, trimethylstyrene, -Styrene monomers such as methyl styrene, p-methyl styrene, p-chloro styrene, p-nitro styrene, P-amino styrene, ⁇ -carboxy styrene, p-phenol styrene, and ethylene, propylene, butadiene, isoprene Copolymerization with other monomers such as, (meth) acrylonitrile, acrylic acrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid, anhydrous maleic acid, vinyl acetate Examples include coalescence. Of
  • the molecular weight of the styrene-based resin is appropriately selected according to the purpose of use.
  • Gel permeation using cyclohexane as a solvent, chromatography The weight average molecular weight (Mw) in terms of polyisoprene measured in, usually 10,000 to 300,000, preferably ⁇ is 15,000 to 250,000, more preferably ⁇ is 20,000 to 200,000 is there.
  • the polystyrene-based resin preferably has a glass transition temperature of 120 ° C or higher 1 120-140 ° C, more preferably 120-140 ° C. .
  • the other thermoplastic resin constituting the b layer preferably has a total light transmittance of 70% or more measured using a test piece having a thickness of 1 mm.
  • a resin include an alicyclic olefin polymer, a methacrylic acid ester resin, a polycarbonate, and a polyether sulfone. Of these, alicyclic olefin polymers are preferred to methacrylic acid ester resin.
  • the alicyclic olefin polymer preferably used in the present invention is an amorphous olefin polymer having a cycloalkane structure in the main chain and Z or side chain. Specifically, (1) norbornene polymer, (2) monocyclic cyclic olefin polymer, (3) cyclic conjugation polymer, (4) vinyl alicyclic hydrocarbon polymer, and these Hydrides of the above. Among these, norbornene polymers are more preferable from the viewpoints of transparency and moldability. Examples of these alicyclic olefin polymers include those described in JP-A No. 05-310845, JP-A No. 05-097978, and US Pat. No. 6,511,756.
  • a methacrylic acid ester resin suitably used in the present invention is a polymer mainly composed of a methacrylic acid ester, and includes a homopolymer of a methacrylic acid ester, a methacrylic acid ester and other monomers.
  • alkyl methacrylate is used as the methacrylic acid ester.
  • acrylic acid esters, aromatic vinyl compounds, burcyan compounds, etc. are used as other monomers copolymerized with methacrylic acid esters.
  • the a layer and the b layer may be provided with an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a dispersant, a chlorine scavenger, a flame retardant, a crystallization nucleus as necessary.
  • Known additives such as thermoplastic elastomers can be added within a range not impairing the effects of the present invention.
  • the styrenic resin and the other thermoplastic resin have glass transition temperatures of Tg (a) (° C) and Tg (b) (° C), respectively. It is preferable that the relationship of Tg (a)> Tg (b) + 20 ° C is satisfied. By satisfying such a relationship, optical anisotropy can be effectively imparted to the a layer made of styrene-based resin when stretched.
  • the method of laminating the styrene-based resin that is the material of the a layer and the other thermoplastic resin that is the material of the b-layer to form a styrene-based resin multilayer film is not particularly limited, Known methods such as coextrusion T-die method, coextrusion inflation method, coextrusion molding method such as coextrusion lamination method, film lamination molding method such as dry lamination, and coating molding method can be used as appropriate. . Among these, a molding method by coextrusion is preferable from the viewpoint of manufacturing efficiency and that volatile components such as a solvent do not remain in the film.
  • the extrusion temperature can be appropriately selected according to the type of the styrene-based resin used and the other thermoplastic resin.
  • the styrene-based resin multilayer film used in the present invention is formed by stacking the b layer on both sides of the a layer.
  • the force that can provide an adhesive layer or adhesive layer between the a layer and the b layer Laminate the a layer and the b layer directly (that is, a layered structure of b layer Za layer Zb layer) ) Is preferred.
  • the average thickness of the a layer and the b layer laminated on both sides thereof is not particularly limited, but preferably 10 to 300 ⁇ m and 10 to 400 ⁇ m, respectively. be able to.
  • a retardation film constituting the brightness enhancement film of the present invention can be obtained by stretching the styrene-based resin multilayer film.
  • This stretched multilayer film can include a layer A provided by stretching a layer and a layer B provided by stretching b layer.
  • This stretched multilayer film (retardation film) is formed by stretching a layered structure of b layer Za layer Zb layer of the above-mentioned styrene-based resin multilayer film, and B layer ZA layer ZB layer three layer structure
  • the stretched film is preferably used.
  • This stretching can be preferably performed by uniaxial stretching or oblique stretching, and more preferably by uniaxial stretching or oblique stretching by a tenter.
  • the interlaminar peel strength between the A layer and the B layer is preferably 1.3 NZ25 mm or more.
  • the delamination strength is According to JIS K-6854-2, the value was measured by 180 ° peeling at a tensile speed of lOOmmZ.
  • the stretched multilayer film preferably has a total light transmittance of 92% or more and a haze of 5% or less. By having such a high total light transmittance and a low haze, the retardation film has good characteristics.
  • nx is a direction perpendicular to the thickness direction and is the maximum Ny represents the refractive index in the direction perpendicular to the thickness direction and perpendicular to nx
  • nz represents the refractive index in the thickness direction
  • d represents the film thickness
  • this retardation film can be used as an alternative to the liquid crystal orientation film used in the conventional brightness enhancement film. Sufficient optical characteristics can be provided.
  • the thickness direction letter-thickness Rth is expressed as an average value of the thickness direction letter-decision values measured at equal intervals in the width direction of the retardation film.
  • the retardation film used in the present invention gives a phase difference of 1Z4 wavelength to incident light.
  • the in-plane direction letter Re represented by 1) represents the phase difference of 1 Z4 wavelength. What we give is called a 1Z4 waveplate.
  • the in-plane direction letter Re is preferably 1Z4 of a wavelength at a wavelength of 550 nm which is the central wavelength of visible light. It is more preferable that the wavelength is approximately 1Z4. About 1Z4 means that it is in the range of 0.15 to 0.40, preferably 0.18 to 0.36, and more preferably 0.20 to 0.30.
  • the in-plane direction letter Re is measured at equal intervals in the width direction of the retardation film, and the in-plane direction letter distortion at each measurement point. Expressed as the average of the values.
  • the sum of the in-plane direction letterings of the A layer and the B layer measured with light having a wavelength of 400 to 700 nm is represented by Re (A) and Re, respectively.
  • Re is the in-plane direction letter measurement that satisfies the equations (1) and (2) and is measured with light having a wavelength of 400 to 700 nm
  • Rth is the letter direction thickness direction.
  • this stretched multilayer film can obtain good optical characteristics as a retardation film.
  • the retardation film used in the present invention can be produced by appropriately adjusting stretching conditions such as a stretching temperature and a stretching ratio.
  • the stretching temperature is preferably Tg (a) -10 (° C) to Tg (a) +20 (° C), Tg (a) -5 (° C) to Tg (a) +15 ( A temperature range of ° C) is particularly preferable.
  • the draw ratio is preferably 1.05 to 30 times, more preferably 1.1 to 10 times. If the stretching temperature or stretching ratio is out of the above range, the orientation may be insufficient and the refractive index anisotropy, and thus the letter expression may be insufficient, or the laminate may be broken.
  • the retardation film used in the present invention preferably has protrusions having a diameter of 0.001 to 0.1 m on at least one side, and the number of protrusions is 50 to 500 ⁇ 30 / ⁇ ⁇ .
  • the polarized light separation film which is a constituent element of the present invention includes a resin layer having cholesteric regularity.
  • the resin layer having cholesteric regularity is preferably a non-liquid crystalline resin layer formed by polymerizing a liquid crystal composition containing a polymerizable liquid crystal compound.
  • Examples of the polymerizable liquid crystal compound constituting the resin layer having the cholesteric regularity of the polarization separation film used in the present invention include a polymerizable liquid crystal compound represented by the following general formula (1). .
  • R 3 and R 4 are reactive groups, and each independently represents a (meth) acryl group, a (thio) epoxy group, an oxetane group, a thietal group, an aziridyl group, a pyrrole group, Represents a group selected from the group consisting of a buyl group, an aryl group, a fumarate group, a cinnamoyl group, an oxazoline group, a mercapto group, an iso (thio) cyanate group, an amino group, a hydroxyl group, a carboxyl group, and an alkoxysilyl group.
  • D 3 and D 4 are a single bond, a linear or branched alkyl group having 1 to 20 carbon atoms, and a linear or branched alkylene oxide having 1 to 20 carbon atoms.
  • One N C, one NHCO, one OCOO, one CH COO—, and one CH OCO force, etc.
  • Represents a group selected from the group consisting of M represents a mesogenic group, specifically, an unsubstituted or halogen atom, a hydroxyl group, a carboxyl group, a cyano group, an amino group, a linear or branched alkyl group having 1 to L0 carbon atoms, Arzomethines, azoxys, biphenyls, terphels, naphthalenes, anthracenes, cyanobiphenols, cyanophyl esters, benzoic acid, optionally substituted with one or more halogenoalkyl groups Esters, cyclohexanecarboxylic acid ester esters, cyanophenylcyclohexanes, cyano-substituted ferrobirimidines, alkoxy-substituted ferrobirimidines, ferrodioxanes, tolans, alkenylcyclohexylbenzo-tolyl 2 to 4 ske
  • the polymerizable liquid crystal compound preferably has an asymmetric structure.
  • the asymmetric structure is a structure in which R 3 — C 3 — D 3 — C 5— and — C 6 — D 4 — C 4 — R 4 are different in the general formula (1) with the mesogenic group M as the center.
  • the polymerizable liquid crystal compound has a ⁇ value (birefringence value) of 0.18 or more, preferably 0.22 or more.
  • the absorption edge on the long wavelength side of the ultraviolet absorption spectrum may extend to the visible range, but the desired optical properties may be achieved even if the absorption edge of the spectrum extends to the visible range. It can be used as long as the performance is not adversely affected.
  • a circularly polarized light separating film having high optical performance can be provided.
  • the polymerizable liquid crystal compound preferably has at least two reactive groups in one molecule.
  • the reactive group include an epoxy group, a thioepoxy group, an oxetane group, a thietal group, an aziridyl group, a pyrrole group, a fumarate group, a cinnamoyl group, an isocyanate group, an isothiocyanate group, Amino group, hydroxyl group, carboxyl group, alkoxysilyl group, mercapto group, bur group, aryl group, methacryl group, acrylic group and the like can be mentioned.
  • a stable cured product can be obtained when the cholesteric resin composition used in the present invention is cured.
  • a compound having 1 or less reactive group in one molecule when used, when the cholesteric resin composition is cured, a crosslinked cured product cannot be obtained, so that a film strength that can withstand practical use cannot be obtained. .
  • the film strength that can withstand practical use is not less than ⁇ , preferably not less than ⁇ in terms of pencil hardness (JIS ⁇ 5400). If it is lower than ⁇ , it is easily scratched and lacks handling.
  • the upper limit of the preferred pencil hardness is not particularly limited as long as it does not adversely affect the optical performance and durability test.
  • the liquid crystal composition that constitutes the cholesteric regularized resin layer used in the present invention may further contain other optional components as necessary.
  • Other optional components include cross-linking agents, photopolymerization initiators, chiral agents, solvents, polymerization inhibitors for improving pot life, anti-oxidation agents for improving durability, UV absorbers, light Stabilizers can be mentioned. These optional components can be added as long as the desired optical performance is not deteriorated.
  • a method for producing a liquid crystal composition constituting the cholesteric regularized resin layer used in the present invention is not particularly limited, and can be produced by mixing the above essential components and optional components.
  • the polarized light separation film as a component of the brightness enhancement film of the present invention is obtained by applying the liquid crystal composition to a transparent resin base material and curing it by at least one heating and Z or light irradiation. .
  • the transparent resin base material is not particularly limited, and a base material having an lmm thickness and a total light transmittance of 80% or more can be used.
  • a base material having an lmm thickness and a total light transmittance of 80% or more can be used.
  • Specific examples include cycloaliphatic olefin polymers, chain olefin polymers such as polyethylene and polypropylene, triacetyl cellulose, polybutyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, and modified acrylic.
  • a monolayer or laminated film made of a synthetic resin such as a polymer or epoxy resin can be used.
  • alicyclic olefin polymers are particularly preferable from the viewpoints of transparency, low hygroscopicity, dimensional stability, light weight and the like, which are preferable for alicyclic olefin polymers or chain olefin polymers.
  • the transparent resin base material may have an alignment film, if necessary.
  • the alignment film By having the alignment film, it is possible to align the liquid crystal composition constituting the resin layer having cholesteric regularity applied thereon in a desired direction.
  • the alignment film is subjected to a corona discharge treatment or the like on the substrate surface as necessary, and then cellulose, silane coupling agent, polyimide, polyamide, polybutyl alcohol, epoxy acrylate, silanol oligomer, polyacrylo-tolyl,
  • a solution prepared by dissolving phenol resin, polyoxazole, cyclized polyisoprene or the like in water or a solvent is applied using a known method such as reverse gravure coating, direct gravure coating, die coating, or bar coating.
  • the average thickness of the alignment film is not particularly limited as long as the desired uniformity of alignment of the resin layer can be obtained, but is preferably 0.001 to 5 / ⁇ ⁇ . More preferably, ⁇ ⁇ .
  • the liquid crystal composition constituting the resin layer having cholesteric regularity is applied to the transparent resin base material by a known method such as reverse gravure coating, direct gravure coating, die coating, bar coating, or the like. Can do.
  • an orientation treatment may be performed as necessary.
  • orientation treatment for example, the coating layer is heated at 50 to 150 ° C for 0.5 to: LO minutes. Can be performed.
  • the alignment treatment the liquid crystal composition constituting the resin layer having cholesteric regularity can be aligned well.
  • the liquid crystal composition constituting the cholesteric regularity resin layer is cured to obtain a polarization separation film having a cholesteric regularity resin layer.
  • the curing step can be performed by at least one heating and Z or light irradiation.
  • the heating condition may be a temperature of 40 to 140 ° C. and a time of 1 second to 3 minutes.
  • the light used for light irradiation includes not only visible light but also ultraviolet rays and other electromagnetic waves.
  • the light irradiation can be performed by, for example, irradiating light having a wavelength of 200 to 500 nm for 0.01 seconds to 3 minutes. Further, for example, it is possible to obtain a polarized light separation film having a wide reflection band by repeating a weak ultraviolet irradiation of 0.01 to 50 mjZcm 2 and heating a plurality of times alternately.
  • the steps of applying and curing the liquid crystal composition constituting the resin layer having cholesteric regularity on the transparent resin base material are not limited to once, and the application and curing are repeated two or more times. It is also possible to form the above-mentioned resin layer.
  • the dry film thickness of the resin layer having cholesteric regularity is preferably 3.0 / ⁇ ⁇ to 10. O / zm, more preferably 3 5-8. O / zm. 3. It is thinner than O / zm! /, And the reflectivity is lowered! /, 10. If it is thicker than O / zm, it will be colored when observed from an oblique direction with respect to the resin layer. I don't like it.
  • FIG. 1 schematically shows a polarized light separation film 1 used in the brightness enhancement film of the present invention.
  • an alignment film 3 is laminated on a substrate 2, and a cholesteric resin layer 4 is laminated on the alignment film 3.
  • the cholesteric resin layer 4 is composed of four layers having different pitches (the pitches are PO, Pl, P2, and P3 layers).
  • the pitch p force increases in the order of PO, Pl, P2, P3.
  • FIG. 1 shows only a chiral structure for one period of each cholesteric resin layer PO, Pl, P2, and P3, the chiral structure may have two or more periods.
  • n (ne + no) Z2 (wherein, no represents the refractive index in the minor axis direction of the polymerizable liquid crystal compound, and ne represents the refractive index in the major axis direction of the polymerizable liquid crystal compound).
  • the reflection band of circularly polarized light reflected by the cholesteric resin layer 4 with the pitch p is expressed by the following formula (3).
  • the adhesive layer constituting the brightness enhancement film of the present invention adheres the retardation film and the polarization separation film, and plays an important role in favorably maintaining the punchability of the brightness enhancement film of the present invention. It is a member that plays.
  • the feature is that the compositional force with a shear storage modulus at a temperature of 23 ° C is 1 to 500 MPa.
  • composition having a shear storage modulus at 23 ° C of 1 to 500 MPa Composition having a shear storage modulus at 23 ° C of 1 to 500 MPa
  • composition constituting the adhesive layer used in the brightness enhancement film of the present invention has a shear storage modulus at a temperature of 23 ° C. of 1 to 500 MPa.
  • the composition contains at least a main polymer constituting an adhesive.
  • the main polymer include acrylic polymers and acrylic copolymers, silicone polymers, polyesters, polyurethanes, polyamides, polybutyl ethers, polybulal alcohols, ethylene z vinyl acetate copolymers, ethylene Z acrylic acids. Ester copolymer, ethylene Z salt butyl copolymer, thermoplastic elastomer, epoxy, natural rubber, synthetic rubber, etc. Is mentioned.
  • thermoplastic elastomer an ethylene Z-butyl acetate copolymer, and an ethylene Z acrylate copolymer are preferable because they are excellent in transparency, exhibit appropriate wettability and cohesion, and have excellent weather resistance.
  • Thermoplastic elastomer is a resin having rubber elasticity at room temperature without vulcanization treatment. Specifically, styrene butadiene block copolymer, styrene ethylene block copolymer, styrene butadiene polystyrene block.
  • Copolymer styrene isoprene styrene block copolymer, styrene-ethylene butylene-styrene block copolymer, styrene-ethylene propylene-styrene block copolymer, ethylene propylene copolymer and ethylene propylene terpolymer, polyethylene, polypropylene and These may be those introduced with a carboxyl group or a sulfonyl group.
  • the molecular weight of these main polymers is the weight average molecular weight (Mw) of polyisoprene measured by gel permeation chromatography, and is usually 10,000 to 500,000, preferably 20,000 to 400,000.
  • other compounding agents can be blended in the composition.
  • other compounding agents include tackifiers, crosslinking agents or curing agents, antioxidants, light diffusing agents, antifoaming agents, and stabilizers.
  • the tackifier described above imparts adhesive force to a main polymer that is soft and strong, and whose solid surface is easily wetted.
  • tackifiers include rosin and rosin derivatives, polyterpene resin, terpene phenol resin, coumarone-indene resin, petroleum resin, hydrogenated petroleum resin and the like.
  • petroleum resin, hydrogenated petroleum resin, and terpene phenol resin are preferred because of their excellent transparency and compatibility with the main polymer.
  • the compounding amount of the tackifier is preferably 2 to 50 parts by weight, more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the main polymer. If the addition amount of the tackifier is less than 2 parts by weight, the effect of the tackifier will not be exhibited. There is a tendency to be seen.
  • crosslinking agent or curing agent examples include tolylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, trimethylolpropane tolylene diisocyanate, diphenylmethane triisocyanate.
  • Polyfunctional isocyanate crosslinking agents such as sulfonates or curing agents; ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether Epoxy crosslinking agents or curing agents such as ter, diglycidyl ether, trimethylolpropane triglycidyl ether; butyltrimethoxysilane, methacryloxypropyltrimethoxysilane, 3 glycidoxypropinoretrimethoxysilane, 2- (3, 4 Epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- (2aminoethyl) 3-aminopropyltrimethoxysilane, and other silane-based crosslinking agents or curing agents; melamine resin A crosslinking agent; a metal chelate crosslinking agent; an amine crosslinking agent is used.
  • the amount of the crosslinking agent or curing agent is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 3 parts by weight with respect to 100 parts by weight of the main polymer.
  • the addition amount of the crosslinking agent or curing agent is less than 0.001 part by weight, the effect of the crosslinking agent is not exhibited, and foaming and peeling are conspicuous in a weather resistance test.
  • the addition amount of the crosslinking agent or curing agent is more than 10 parts by weight, the stress relaxation property of the adhesive is lowered, and warpage becomes conspicuous.
  • Examples of the above-mentioned anti-oxidation agent include tetrakis (methylene 3- (3,5-di-tert-butyl 4-hydroxyphenyl) propionate) phenol-based anti-oxidation agents such as methane, phosphorus-based antioxidants, Examples include thioether-based antioxidants.
  • the blending amount of the antioxidant is within a range where the transparency and adhesive strength of the adhesive layer are not lowered.
  • the shear storage modulus of the composition constituting the adhesive layer used in the present invention varies depending on the main polymer yarn and the addition amount of the tackifier, the addition amount of the crosslinking agent, and the like.
  • the shear storage modulus at room temperature tends to decrease by increasing the ratio of the monomer that becomes the soft segment in the copolymer. Conversely, increasing the ratio of monomers that become hard segments tends to increase the shear storage durability at room temperature. Also in the same composition, by reducing the molecular weight of the polymer, the temperature range showing the rubber-like flat region is narrowed, and the shear storage modulus at room temperature tends to decrease. On the other hand, increasing the molecular weight of the polymer tends to increase the temperature range showing the rubbery flat region and increase the shear storage modulus at room temperature. Tackifiers generally have a high softening point of 60 degrees or higher and a low molecular weight of about several thousand.
  • the cohesive strength of the adhesive composition is lowered, and a decrease in shear storage elasticity at room temperature is observed.
  • the cohesive strength of the adhesive composition is increased by mixing the cross-linking agent, and an increase in the shear storage modulus at room temperature is observed.
  • the shear storage elastic modulus at 23 ° C of the composition that is, the hot-melt adhesive, must be adjusted to 1 to 500 MPa. If the shear storage modulus at 23 ° C is less than 1 MPa, adhesiveness will develop at room temperature, and adhesive residue will occur on the punching blade and tab agent during post-processing such as punching of laminated film.
  • the shear storage modulus at 23 ° C exceeds 500MPa, it must be heated to a high temperature, for example, over 110 ° C, in order to develop the adhesiveness required to laminate the film. It must be. At temperatures above 110 ° C, the heat load on the film is too great and the film may be deformed. Moreover, the adhesive force with the film of an adhesive agent also falls.
  • the shear storage modulus at 23 ° C. of the composition is preferably 2 to 300 MPa, more preferably 5 to 250 MPa.
  • the 180 degree peel adhesive strength of the brightness enhancement film laminated with the adhesive may be ION Z 25 mm or more.
  • the total light transmittance of the adhesive layer in the laminated brightness enhancement film can be set to 80% or more, and more than 85%, and because it has a retardation film S styrene resin layer, it is highly transparent.
  • the transparency of the brightness enhancement film of the present invention can be higher than that of conventional products.
  • the composition When the composition is used as an adhesive, the composition is dissolved or dispersed in a solvent or water.
  • a solvent or water As the solvent, toluene, ethyl acetate, butyl acetate, isobutyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, isobutyl alcohol, etc. should be used. Can do.
  • the average thickness of the adhesive layer is preferably 2 ⁇ m to 50 ⁇ m, more preferably 5 ⁇ m to 30 ⁇ m.
  • the average thickness is represented by the average value of the measured values at each measurement point when the thickness of the adhesive layer is measured at equal intervals in the width direction.
  • the method for producing a brightness enhancement film of the present invention includes a step of bonding the polarization separation film and the retardation film through the adhesive layer.
  • the bonding step includes the steps of bonding the polarization separation film and the Retardation film in the range of 40 ° C to 110 ° C It is characterized by being bonded by heating.
  • the composition constituting the adhesive layer is directly applied to a polarized light separation film or retardation film and dried; a polyethylene terephthalate film or a silicone-based or fluorine-based film is used.
  • the method of applying the adhesive is not particularly limited, and examples thereof include a roll coating method, a gravure coating method, a spin coating method, and a bar coating method.
  • the coating surface is appropriately subjected to plasma discharge treatment, corona discharge treatment, ultraviolet ray in order to improve wettability and adhesion. It may be treated or flame treated.
  • the composition constituting the adhesive layer when the composition constituting the adhesive layer is formed on the polarization separation film, it may be formed in view of the luminance improvement rate and the appearance when mounted on a liquid crystal display device.
  • the luminance improvement rate is a value represented by a ratio between the luminance value when the luminance enhancement film according to the present invention is installed in the liquid crystal display device and the luminance value when it is installed.
  • the adhesive layer and the polarization separation film or retardation film on which the adhesive layer is not formed are bonded together by heating in the range of 40 ° C to 110 ° C.
  • the bonded surface of the polarization separation film or retardation film is preferably subjected to plasma discharge treatment, corona discharge treatment, ultraviolet treatment, and flame treatment in order to enhance adhesion. If the laminating temperature is less than 40 ° C, adhesion between the polarization separation film and the retardation film becomes insufficient. Conversely, if it exceeds 110 ° C, deformation or warping of the film tends to occur.
  • a preferable range of the bonding temperature is 60 ° C to 100 ° C.
  • the polarization separation film 1 is combined with a 1Z4 wavelength plate through a specific adhesive layer described later to form a brightness enhancement film, and the brightness enhancement film is composed of the polarizer X, the liquid crystal cell, and the polarizer Y.
  • the brightness was improved by arranging the polarizer X, the liquid crystal cell, the polarizer Y, and the brightness enhancement film of the present invention (retardation film + adhesive layer + polarization separation film) in this order. To get a liquid crystal display it can.
  • Polarizers X and Y used in the present invention are known polarizers used in liquid crystal display devices and the like.
  • the polarizer used in the present invention transmits one of two linearly polarized light intersecting at right angles.
  • a hydrophilic polymer film such as a polybulualcohol film or ethylene acetate bull partially saponified film adsorbed with a dichroic substance such as iodine or a dichroic dye and uniaxially stretched, or the hydrophilic polymer film Examples thereof include a film obtained by uniaxially stretching a film to adsorb a dichroic material, and a polyethylene oriented film such as a dehydrated polyvinyl alcohol product or a dechlorinated polyvinyl chloride treated product.
  • a polarizer having a function of separating polarized light into reflected light and transmitted light such as a grid polarizer and a multilayer polarizer. Of these, polarizers containing polybulal alcohol are preferred
  • the polarization degree of the polarizer used in the present invention is not particularly limited, but is preferably 98% or more, more preferably 99% or more.
  • the average thickness of the polarizer is preferably 5 to 80 ⁇ m.
  • the polarization transmission axis of the polarizer X and the polarization transmission axis of the polarizer Y are arranged so as to be perpendicular to each other with the liquid crystal cell sandwiched therebetween. Polarizer performance may change due to moisture absorption. To prevent this, protective films are usually attached to both sides of the polarizer X or Y.
  • a liquid crystal material is filled between two glass substrates provided with transparent electrodes facing each other with a gap of several ⁇ m, and a voltage is applied to the electrodes to change the alignment state of the liquid crystals. It controls the amount of light passing through here.
  • the liquid crystal cell is classified according to a method (operation mode) for changing the alignment state of the liquid crystal substance.
  • a TN (Twisted Nematic) type liquid crystal cell for example, a TN (Twisted Nematic) type liquid crystal cell, an STN (Super Twisted Nematic) type liquid crystal cell, and a HAN (Hybrid) Alignment Nematic) type liquid crystal cell, IPS (In Plane Switching) type liquid crystal senore, VA (Vertical Alignment) type liquid crystal senore, MVA (Multiple Vertical Alignment type liquid crystal senore), OCB (Optical Compensate d Bend) type liquid crystal cell .
  • IPS In Plane Switching
  • VA Very Alignment
  • MVA Multiple Vertical Alignment type liquid crystal senore
  • OCB Optical Compensate d Bend
  • FIG. 2 is a diagram showing an example of the liquid crystal display device of the present invention.
  • a reflector 10, a cold cathode tube 11, a diffuser 12, a prism sheet (not shown), a polarization separation film 1 and a retardation film 13 are laminated via an adhesive layer 14.
  • Brightness enhancement film 15, polarizer Y16, liquid crystal cell 17, and polarizer X18 are arranged in this order.
  • Light with a light source includes right and left polarized light. When the light enters the polarization separation film 1, the circularly polarized light in one rotation direction (circularly polarized light in the right direction toward the traveling direction of light in the figure) passes through the polarization separation film 1 while maintaining the same rotation direction. To do.
  • the other circularly polarized light in the rotation direction (in the figure, circularly polarized light counterclockwise toward the light traveling direction) is reflected by the polarization separation film 1 (the reflected circularly polarized light is rotated counterclockwise toward the light traveling direction).
  • the transmitted circularly polarized light is converted into linearly polarized light parallel to the transmission axis of the polarizer Y16 by the retardation film 13 fixed to the polarization separation film 1 through the adhesive layer 14.
  • the reflected circularly polarized light becomes non-polarized light by the diffuser plate 12, is reflected by the reflector plate 10 disposed behind the light source 11, and is incident on the polarization separation film 1 again. In this way, the light emitted from the light source 11 is effectively used, and the display brightness of the screen can be improved.
  • the diffusion plate 12 is generally known as a plate having a function in which a particulate diffusion material is uniformly dispersed in a matrix such as a resin, thereby scattering and diffusing light. It is.
  • the prism sheet is generally known as a sheet having a function of narrowing light having a wide traveling direction due to scattering or the like in the normal direction of the sheet surface.
  • a diffusion sheet may be interposed and fixed between the polarization separation film 1 and the adhesive layer 14 or between the adhesive layer 14 and the phase difference film 13.
  • the diffusion sheet is generally a laminate on which a particulate diffusion material is uniformly dispersed on a transparent film, and is known as a sheet having a function of scattering and diffusing light.
  • the surface of the polarization separation film 1 on the phase difference film 14 side has light diffusibility.
  • the light diffusibility is a property of scattering and diffusing light.
  • Examples of the present invention will be described below. The present invention is not limited to the following examples. [0094] Examples 1 to 4 and Comparative Examples 1 to 3 are shown below. In these, the retardation film and the polarization separation film constituting the brightness enhancement film were the same, and only the configuration of the adhesive layer was changed.
  • One side of a film consisting of an alicyclic olefin polymer with an average thickness of 100 m, width of 50 mm, and length of 200 mm (trade name “Zeonor Film” manufactured by Optes Co., Ltd.) (hereinafter referred to as “base material”).
  • base material a film consisting of an alicyclic olefin polymer with an average thickness of 100 m, width of 50 mm, and length of 200 mm (trade name “Zeonor Film” manufactured by Optes Co., Ltd.) (hereinafter referred to as “base material”).
  • base material a film consisting of an alicyclic olefin polymer with an average thickness of 100 m, width of 50 mm, and length of 200 mm.
  • the corona discharge treatment was applied so that the wetting index was 56 dyneZcm.
  • a coating solution having the composition shown in Table 1 below was applied using a wire bar # 6, heated at 100 ° C for 5 minutes, dried, and alignment-aged.
  • the coated film after aging is irradiated with UV light of 70 mjZcm 2 (UV-A), held at 100 ° C for 5 minutes, and then irradiated with UV light to cure the coating film, resulting in an average film thickness of 3 m.
  • a resin layer was formed to obtain a polarized light separation film.
  • the obtained cholesteric resin layer had a light transmittance from 400 nm to 750 nm of 55% and a reflectance of 35%.
  • Rubber particles were produced according to Example 3 of JP-B-55-27576.
  • This rubber particle has a spherical three-layer structure, the core inner layer is a crosslinked polymer of methyl methacrylate and a small amount of methacrylate, and the inner layer is composed of butyl acrylate and styrene as main components and a small amount.
  • It is a soft elastic copolymer obtained by crosslinking copolymerization with an amount of allylic acrylate, and the outer layer is a hard polymer of methyl methacrylate and a small amount of ethyl acrylate.
  • the average particle size of the inner layer was 0.19 m, and the particle size including the outer layer was 0.22 m.
  • the methacrylic acid ester polymer composition A (layer b) and the styrene maleic anhydride copolymer (glass transition temperature 130 ° C) (layer a) were coextruded at a temperature of 280 ° C.
  • This multilayer film was stretched uniaxially with a tenter at a stretching temperature of 128 ° C., a stretching ratio of 1.4 times, and a stretching speed of 10 mZ to obtain a stretched multilayer film (retardation film). Furthermore, one side of this retardation film was subjected to corona discharge treatment so that the wetting index was 56 dyneZcm.
  • the retardation value of the obtained retardation film at a wavelength of 550 nm is the thickness direction.
  • Letter decision Rth is 118nm
  • in-plane letter decision Re is 140nm.
  • Each adhesive solution was placed in a measuring cup and placed in a dryer at 80 ° C for 10 hours and at 100 ° C for 30 minutes to remove moisture, and a sample having a thickness of about 1.5 mm was prepared. This sample was cut to a diameter of 8 mm and the temperature was 23 using a viscoelasticity measuring device (RheoStress RS600, manufactured by Eihiro Seiki). The measurement was performed under the conditions of C, frequency 1 ⁇ , and strain amount 0.5%.
  • Ethylene acetate butyl copolymer emulsion (non-volatile content 40% by weight, vinyl acetate content 40% by weight) 40 parts by weight, petroleum oil emulsion (non-volatile content 40% by weight, resin softness point 85 ° C) 35% Part and paraffin wax emulsion (non-volatile content 40% by weight, resin softening point 64 ° C)
  • Adhesive layer formed of a composition having a shear storage modulus of lOMPa at 23 ° C, which is 10 parts by weight Is laminated on the cholesteric resin layer of the polarized light separating film so that the average thickness is 20 m, and the corona-treated surface of the retardation film is laminated with a laminator at 80 ° C. and 2 kgfZ50 mm. Bonding was performed under pressure to obtain a brightness-enhanced FINEREM 1.
  • Ethylene acetate butyl copolymer emulsion (non-volatile content 40% by weight, vinyl acetate content 25% by weight) 73 parts by weight Petroleum resin emulsion (non-volatile content 40% by weight, soft oil soft point 85 ° C) 2% Part and paraffin wax emulsion (nonvolatile content 40% by weight, resin softening point 64 ° C) 10 parts by weight, formed of a composition having a shear storage modulus at 23 ° C of lOOMPa
  • An adhesive layer is laminated on the cholesteric resin layer of the polarized light separating film so that the average thickness is 15 m, and the corona-treated surface of the retardation film is 90 ° C, 2 kgfZ50 mm, using a laminator. -Brightening film 2 was obtained by pasting together with the pressure.
  • It is composed of a composition (made of Showa Polymer Co., Ltd., Polysol L6850) having a shear storage elastic modulus at 23 ° C of 50 MPa, based on a styrene acrylate copolymer.
  • An adhesive layer is laminated on the cholesteric resin layer of the polarized light separating film so that the average thickness is 18 m, and the corona-treated surface of the retardation film is laminated with a laminator at 80 ° C. and 2 kgfZ50 mm. Bonding was performed under pressure to obtain a brightness enhancement film 3.
  • An adhesive layer made of a composition (asaprene T436, manufactured by Asahi Kasei Chemicals Co., Ltd.) having a pruned storage elastic modulus at 23 ° C of lOOMPa based on a styrene-butadiene-styrene copolymer as a base polymer is used as the cholesteric resin of the polarized light separating film.
  • the film is laminated so that the average thickness is 15 m on the layer, and the corona-treated surface of the retardation film is laminated using a laminator at 90 ° C, 2 kgfZ50 mm -pump pressure, and the brightness enhancement film Got 4.
  • An adhesive layer comprising a composition (E-5301, manufactured by Daido Kasei Kogyo Co., Ltd.) having a shear storage elastic modulus at 23 ° C of 0. IMPa as a base polymer is used as a cholesteric resin for the polarized light separation film.
  • Ethylene acetate butyl copolymer emulsion (non-volatile content 40% by weight, vinyl acetate content 10% by weight) 75 parts by weight, paraffin wax emulsion (non-volatile content 40% by weight, resin softness point 64 ° C) 10
  • a composition having an acrylic ester copolymer as a base polymer and a shear storage modulus at 23 ° C of force ⁇ OOMPa (7980 made by Nichigomo Vinyl) has an adhesive layer on the cholesteric resin layer of the polarizing separation film. Laminate the corona-treated surface of the above retardation film with an average thickness of 18 m using a laminator. -Bonding was performed at a pressure, and a brightness enhancement film 7 was obtained.
  • a 180 degree peel test (polarized separation film as a rigid substrate and a phase difference film as a flexible substrate) was performed on the brightness enhancement film of each example in accordance with JIS K6854-2. . The case where cohesive failure occurred without delamination was judged good, and the case where delamination occurred was judged as poor. The results are shown in Table 2 below.
  • the brightness enhancement film of each example was cut into a 50 mm X 50 mm size rectangle with a trimming force razor blade, and the presence or absence of adhesion of the adhesive to the blade at that time was visually observed. The results are also shown in Table 2 below.
  • the shear elastic modulus at 23 ° C of the adhesive layer is set in the range of 1 to 500 MPa, the adhesiveness is good, and the adhesive does not adhere to the punching blade. won.
  • Comparative Example 1 in which the shear modulus of the adhesive at 23 ° C. was 0. IMPa, the adhesive property was good, but the adhesive adhered to the punching blade.
  • Comparative Example 2 (lOOOMPa) and Comparative Example 3 (800 MPa) where the shear modulus of the adhesive at 23 ° C was set to a value exceeding 500 MPa, the adhesive did not adhere to the punching blade, but delamination occurred. As a result, the adhesiveness was poor.
  • the backlight unit consisting of a reflector, cold cathode tube, diffuser plate and prism sheet, Polarizer Y, Brightness-type liquid crystal cell, Polarized light obtained by placing the brightness-enhancing film 1 produced in Example 1 with the polarizing separation film (A) side facing the diffusion plate and adsorbing iodine to polybulal alcohol
  • a polarizer X similar to the child, was placed in this order to produce a liquid crystal display device as shown in Fig. 2.
  • This liquid crystal display device was caused to emit light in the white display mode and observed from the light exit surface side.
  • the display surface was not colored over the entire surface, and unevenness due to the lack of the adhesive layer was observed at the edge of the brightness enhancement film.
  • a liquid crystal display device was produced by incorporating it into the knocklight unit in the same manner as in Example 5 except that the brightness enhancement film was changed to that produced in Comparative Example 1.
  • This liquid crystal display device was caused to emit light in the white display mode in the same manner as in Example 5 and observed from the light exit surface side. Although the display surface was not colored over the entire surface, unevenness due to the chipping of the adhesive layer was observed at the edge of the brightness enhancement film.
  • the brightness enhancement film according to the present invention has good transparency and punching workability, and can reduce the product cost, and various types of liquid crystal display devices can be used.
  • the luminance of the display device can be improved and the cost of the display device can be reduced.

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  • Physics & Mathematics (AREA)
  • Chemical & Material Sciences (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • General Physics & Mathematics (AREA)
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  • Polarising Elements (AREA)

Abstract

Disclosed is a luminance improving film which is improved in transparency and punchability, while being reduced in production cost. Also disclosed is a method for producing such a luminance improving film. Specifically, a multilayer film comprising a retardation film obtained by stretching a resin film having a styrene resin layer, a polarization splitting film comprising a resin layer having cholesteric regularity, and an adhesive layer arranged between the retardation film and the polarization splitting film and composed of a composition having a shear storage modulus at 23˚C of 1-500 MPa, is used as the luminance improving film.

Description

明 細 書  Specification
輝度向上フィルム、その製造方法、および液晶表示装置  Brightness enhancement film, method for producing the same, and liquid crystal display device
技術分野  Technical field
[0001] 本発明は、光源からの光を偏光化する機能を有し、他の光学フィルムと組み合わせ て、液晶表示装置、有機 EL表示装置、プラズマディスプレイパネルなどの表示装置 に用いることにより、前記表示装置おける光の利用効率を図って明るい表示を実現 することのできる輝度向上フィルム、その製造方法、および液晶表示装置に関する。 背景技術  The present invention has a function of polarizing light from a light source, and is used in a display device such as a liquid crystal display device, an organic EL display device, or a plasma display panel in combination with another optical film. The present invention relates to a brightness enhancement film capable of realizing a bright display by improving light use efficiency in a display device, a manufacturing method thereof, and a liquid crystal display device. Background art
[0002] 従来、液晶セルの裏側サイドには、偏光板と輝度向上フィルムを貼り合わせた偏光 板が設けられている。輝度向上フィルムは、液晶表示装置などのノ ックライトや裏側 力 の反射などにより自然光が入射すると所定偏光軸の直線偏光または所定方向の 円偏光を反射し、他の光は透過する特性を示すもので、輝度向上フィルムを偏光板 と積層した偏光板は、ノ ックライト等の光源からの光を入射させて所定偏光状態の透 過光を得ると共に、前記所定偏光状態以外の光は透過せずに反射される。この輝度 向上フィルム面で反射した光を更にその後ろ側に設けられた反射層等を介し反転さ せて輝度向上フィルムに再入射させ、その一部又は全部を所定偏光状態の光として 透過させて輝度向上フィルムを透過する光の増量を図ると共に、偏光子に吸収させ にくい偏光を供給して液晶表示画像表示等に利用しうる光量の増大を図ることにより 輝度を向上させうるものである。  Conventionally, a polarizing plate having a polarizing plate and a brightness enhancement film bonded to each other is provided on the back side of the liquid crystal cell. The brightness enhancement film shows the characteristic that when natural light is incident due to a knock light such as a liquid crystal display device or reflection of back side force, it reflects linearly polarized light with a predetermined polarization axis or circularly polarized light in a predetermined direction and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a knock light to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting through light other than the predetermined polarization state. Is done. The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. The brightness can be improved by increasing the amount of light transmitted through the brightness enhancement film and increasing the amount of light that can be used for liquid crystal display image display etc. by supplying polarized light that is difficult to be absorbed by the polarizer.
[0003] 前記輝度向上フィルムとしては、例えば誘電体の多層薄膜や屈折率異方性が相違 する薄膜フィルムの多層積層体の如き、所定偏光軸の直線偏光を透過して他の光は 反射する特性を示すもの、コレステリック液晶ポリマーの配向フィルムやその配向液 晶層をフィルム基材上に支持したものの如き、左回り又は右回りのいずれか一方の 円偏光を反射して他の光は透過する特性を示すものなどが提案されている。  [0003] The brightness enhancement film transmits a linearly polarized light having a predetermined polarization axis and reflects other light, such as a dielectric multilayer thin film or a multilayer laminate of thin film films having different refractive index anisotropies. Reflects either left-handed or right-handed circularly polarized light and transmits other light, such as those exhibiting properties, such as those in which a cholesteric liquid crystal polymer oriented film or its oriented liquid crystal layer is supported on a film substrate Proposals have been made for characteristics.
[0004] 中でも、コレステリック液晶層の如く円偏光を透過するタイプの輝度向上フィルムで は、そのまま偏光子に入射させることもできるが、吸収ロスを抑制する点よりその円偏 光を位相差板を介し直線偏光化して偏光板に入射させることが好まし ヽ。その位相 差板としては 1Z4波長板を用いることにより、円偏光を直線偏光に変換することがで きる。通常、コレステリック液晶層の如く円偏光を透過するタイプの輝度向上フィルム では、コレステリック液晶層と 1Z4波長板とを、他の接着手段を介して積層させて用 いられており、いろいろな提案がなされている。 [0004] Among them, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be incident on a polarizer as it is, but the circularly polarized light is applied to a retardation plate from the viewpoint of suppressing absorption loss. It is preferable that the light is linearly polarized and incident on the polarizing plate. Its phase By using a 1Z4 wavelength plate as the difference plate, circularly polarized light can be converted to linearly polarized light. In general, brightness enhancement films that transmit circularly polarized light, such as cholesteric liquid crystal layers, use a cholesteric liquid crystal layer and a 1Z4 wave plate laminated via other adhesive means, and various proposals have been made. ing.
[0005] 例えば、特許文献 1 (特許第 3373374号公報）、及び特許文献 2 (特開平 11 00 2722号公報）には、コレステリック液晶層からなる偏光分離フィルムと 1Z4波長板と を応力緩和性に優れる粘着層を介して接着した積層体力ゝらなる輝度向上フィルムが 、開示されている。また、特許文献 3 (特開 2004— 191803号公報）には、コレステリ ック液晶フィルム、液晶配向フィルムおよび位相差板の各層が接着手段を介して積 層されてなり、前記接着手段のいずれか少なくとも 1つが、接着剤層であり、かつ 23 °Cにおける貯蔵弾性率が 0. 5〜： LOOMPaである輝度向上フィルムが、開示されてい る。 [0005] For example, Patent Document 1 (Japanese Patent No. 3373374) and Patent Document 2 (Japanese Patent Application Laid-Open No. 11 00 2722) describe that a polarizing separation film composed of a cholesteric liquid crystal layer and a 1Z4 wavelength plate have stress relaxation properties. There has been disclosed a brightness enhancement film having a laminate strength bonded through an excellent adhesive layer. Patent Document 3 (Japanese Patent Application Laid-Open No. 2004-191803) is formed by stacking layers of a cholesteric liquid crystal film, a liquid crystal alignment film, and a retardation plate via an adhesion means, and any one of the adhesion means. A brightness enhancement film is disclosed in which at least one is an adhesive layer and the storage modulus at 23 ° C. is from 0.5 to: LOOMPa.
発明の開示  Disclosure of the invention
発明が解決しょうとする課題  Problems to be solved by the invention
[0006] 前記輝度向上フィルムは、まず、基本的に光の透過性が良好なことが大切である。  [0006] First, it is important that the brightness enhancement film has good light transmittance.
その上で、光源や反射層からの自然光を効率的に直線偏光化する機能において、 元の自然光の直線偏光への変換効率がより高いことが重要となる。  In addition, in the function of efficiently converting the natural light from the light source and the reflective layer into linearly polarized light, it is important that the conversion efficiency of the original natural light to linearly polarized light is higher.
[0007] また、前記輝度向上フィルムが使用される液晶表示装置などの表示装置は、予期 せぬ外力を受けたり、温度変化の激しい環境下で利用される。例えば、携帯電話は 、使用者とともに様々な環境下を移動するので、その液晶装置には、様々な外力と温 度変化が力かり続ける。またカーナビゲーシヨン装置に用いられている液晶表示装置 は、昼夜を通して温度が激しく変化する車中において使用される。そのため、外力や 温度変化に対して十分な物理的耐久性を有することが重要となる。  [0007] In addition, a display device such as a liquid crystal display device in which the brightness enhancement film is used is used under an environment where an unexpected external force is applied or a temperature change is severe. For example, since mobile phones move with the user in various environments, various external forces and temperature changes continue to be exerted on the liquid crystal device. Liquid crystal display devices used in car navigation systems are used in vehicles where the temperature changes drastically throughout the day and night. For this reason, it is important to have sufficient physical durability against external forces and temperature changes.
[0008] また、前記輝度向上フィルムは、様々なサイズの表示装置に適用するために、それ ぞれの適用先の表示装置に合わせて、所望のサイズに打ち抜き加工されるが、ブラ スチックフィルムの積層体であるため、打ち抜き時の加工性が良好であることが重要 となる。  [0008] Further, in order to apply the brightness enhancement film to display devices of various sizes, the brightness enhancement film is punched into a desired size according to the display device of each application destination. Since it is a laminate, it is important that the workability during punching is good.
[0009] さらに、液晶表示装置を始めとする表示装置は、近年、様々な用途に大量に使用さ れる傾向にあり、製造コストの低減、特に使用材料面でのコスト低減が重要となる。 Furthermore, display devices such as liquid crystal display devices have been used in large quantities for various purposes in recent years. Therefore, it is important to reduce manufacturing costs, particularly in terms of materials used.
[0010] 輝度向上フィルムという製品には、前述のように、高い透明性、光利用効率の向上 [0010] As described above, the product called brightness enhancement film has high transparency and improved light utilization efficiency.
、物理的耐久性の向上、打ち抜き加工性の向上、および製造コストの低減の諸条件 力 それぞれ他の条件を犠牲にすることなぐ同時に実現することが、重要な条件と なる。 Conditions for improving physical durability, punching workability, and reducing manufacturing costs are important conditions that must be realized at the same time without sacrificing other conditions.
[0011] 前述の諸特性を実現するとの観点から、前記従来の輝度向上フィルムを検討すると 、特許文献 1に開示の偏光素子は、粘着層を介して偏光分離フィルムと 1Z4波長板 とを貼り合わせており、そのため、打ち抜き加工時に、打ち抜き刃に粘着成分が付着 したり、粘着剤層の伸びが発生し、加工の効率が低下し、打ち抜き品の形状特性も 不十分となる。  [0011] From the viewpoint of realizing the above-mentioned various characteristics, the conventional brightness enhancement film is studied. The polarizing element disclosed in Patent Document 1 is obtained by laminating a polarization separation film and a 1Z4 wavelength plate via an adhesive layer. Therefore, at the time of punching, an adhesive component adheres to the punching blade or an adhesive layer is stretched, the processing efficiency is lowered, and the shape characteristics of the punched product become insufficient.
[0012] また、特許文献 2では、前記特許文献 1と同様に加工性における問題点に加えて、 偏光分離フィルムにコレステリック液晶ポリマーを用いているため、その配向性を高め ることが難しぐ光の偏光化効率をさらに向上させることが難しい。  [0012] In addition, in Patent Document 2, in addition to the problem in processability as in Patent Document 1, since a cholesteric liquid crystal polymer is used for the polarization separation film, it is difficult to improve the orientation. It is difficult to further improve the polarization efficiency.
[0013] また、特許文献 3は、 3種のフィルムを接着手段によって一体ィ匕しており、積層体の 耐クラック性を向上するために、粘着剤層と接着剤層とを使い分けて、使用している。 すなわち、コレステリック液晶フィルム 粘着剤層一液晶配向フィルム 接着剤層 位相差板という積層構造を採用している。つまり、粘着剤と接着剤とを併用することで 、各フィルムへの応力を緩和して、耐クラック性の向上を図っている。し力しながら、こ の特許文献 3の輝度向上フィルムは、粘着剤を使用している点では、先の特許文献 1 と 2と同様であり、この輝度向上フィルムには、打ち抜き刃への粘着剤の付着および 粘着剤層の伸びという解決すべき問題が同様に存在する。また、 5層の積層構造で あるため、製造工程が複雑になり、歩留まりが低下する。さらに、この特許文献 3の輝 度向上フィルムは、液晶配向フィルムを必須要素として具備しているので、構成が複 雑となる。  [0013] In Patent Document 3, three types of films are integrated by an adhesive means, and the pressure-sensitive adhesive layer and the adhesive layer are used separately in order to improve the crack resistance of the laminate. is doing. That is, a laminated structure of a cholesteric liquid crystal film, an adhesive layer, a liquid crystal alignment film, an adhesive layer, and a retardation plate is employed. That is, by using a pressure-sensitive adhesive and an adhesive in combination, stress on each film is relaxed and crack resistance is improved. However, the brightness enhancement film of Patent Document 3 is the same as Patent Documents 1 and 2 in that an adhesive is used. This brightness enhancement film has an adhesion to a punching blade. There are also problems to be solved, such as adhesive adhesion and adhesive layer elongation. In addition, since it has a five-layer structure, the manufacturing process becomes complicated and the yield decreases. Furthermore, since the brightness enhancement film of Patent Document 3 includes a liquid crystal alignment film as an essential element, the configuration is complicated.
[0014] さらに、特許文献 1、 2、 3を代表とする従来の輝度向上フィルム一般に要求される 問題として、さらなる透明性の向上がある。これに対して、例えば、位相差フィルムとし て透明性の高 、高分子材料であるスチレン系榭脂層を有する複層フィルムを用いる ことが考えられる力 この複層フィルムは、比較的高い硬度を有するため、打ち抜き 時にクラック等の打ち抜き不良を生じるおそれがある。 [0014] Further, as a problem generally required for conventional brightness enhancement films represented by Patent Documents 1, 2, and 3, there is a further improvement in transparency. On the other hand, for example, it is possible to use a multilayer film having a highly transparent and high-molecular material styrene-based resin layer as the retardation film. This multilayer film has a relatively high hardness. To have punched Sometimes there is a risk of punching defects such as cracks.
[0015] 本発明は、上記従来の問題点に鑑みてなされたものであって、その課題は、透明 性の向上、打ち抜き加工性の向上、製品コストの低減ィ匕を可能にした輝度向上フィ ルムおよびその製造方法を提供することにある。  [0015] The present invention has been made in view of the above-mentioned conventional problems, and its problems are improved brightness, improved transparency, improved punchability, and reduced product cost. It is to provide a rumm and a manufacturing method thereof.
課題を解決するための手段  Means for solving the problem
[0016] 上述した課題を達成するために、本発明の輝度向上フィルムは、スチレン系榭脂層 を含む榭脂フィルムを延伸してなる位相差フィルム、コレステリック規則性を有する榭 脂層を含む偏光分離フィルム、および前記位相差フィルムと前記偏光分離フィルムと の間に、温度 23°Cにおける剪断貯蔵弾性率が l〜500MPaである組成物力もなる 接着層を含むことを特徴とする。  In order to achieve the above-described problems, the brightness enhancement film of the present invention is a retardation film obtained by stretching a resin film including a styrene-based resin layer, and a polarizing film including a resin layer having cholesteric regularity. It is characterized by comprising a separation film, and an adhesive layer between the retardation film and the polarization separation film, which also has a compositional force with a shear storage modulus of 1 to 500 MPa at a temperature of 23 ° C.
[0017] スチレン系榭脂層を含む榭脂フィルムを位相差フィルムの構成材料として使用する ことにより、本発明の輝度向上フィルムを液晶表示装置に搭載した時に、輝度向上フ イルムに斜めから入射した光のうち出射してきた光を有効的に所望の偏光として取り 出すことができる。また、温度 23°Cにおける剪断貯蔵弾性率が l〜500MPaである 組成物からなる接着層を用いて、スチレン系榭脂層を含む榭脂フィルムを延伸してな る位相差フィルムと、偏光分離フィルムとを一体に接着し、良好な接着性と応力緩和 性を同時に実現しているので、フィルムの打ち抜き加工性を良好な範囲に保つことが できる。  [0017] By using a resin film including a styrene-based resin layer as a constituent material of a retardation film, the film is incident on the brightness enhancement film obliquely when the brightness enhancement film of the present invention is mounted on a liquid crystal display device. Of the light, the emitted light can be effectively extracted as the desired polarized light. In addition, a retardation film formed by stretching a resin film including a styrene-based resin layer using an adhesive layer composed of a composition having a shear storage modulus of 1 to 500 MPa at a temperature of 23 ° C, and polarization separation Since the film is bonded together and good adhesion and stress relaxation are realized at the same time, the punching workability of the film can be kept within a good range.
[0018] 本発明において、接着剤とは、常温 (20± 15°C :JIS規格）において粘着性を示さ ない接着性物質を意味し、粘着剤とは、常温において粘着性を示す接着性物質を 意味する。従って、前記接着層は常温で粘着性を示さないものである。本発明でいう 、粘着性を示さないとは、 JIS Z0237の傾斜式ボールタック測定による測定で、ボー ルナンバーで 2未満の粘着性を示すことを 、う。  [0018] In the present invention, the adhesive means an adhesive substance that does not exhibit tackiness at room temperature (20 ± 15 ° C: JIS standard), and the adhesive refers to an adhesive substance that exhibits tackiness at room temperature. Means. Therefore, the adhesive layer does not exhibit tackiness at room temperature. In the present invention, “not showing tackiness” means showing tackiness of less than 2 in ball number as measured by JIS Z0237 tilted ball tack measurement.
[0019] 位相差フィルム及び偏光分離フィルムを接着剤により積層することによって、積層 体である輝度向上フィルムの打ち抜きカ卩ェ時において、打ち抜き刃への接着剤のこ びり付きを防止することができる。  [0019] By laminating the retardation film and the polarization separation film with an adhesive, sticking of the adhesive to the punching blade can be prevented during the punching of the brightness enhancement film as a laminate. .
[0020] 前記接着層の厚みは 2 πι〜50 /ζ mであることが好ましい。本発明に用いる接着 剤は、常温において粘着性を持たない、いわゆるホットメルト型の接着剤であるので、 厚みが 2 m未満となると、常温下における接着性が不十分になり、接着剤の介装に よる積層フィルム間の応力緩和性が不十分になるおそれがある。逆に、 50 mを超 えると、接着剤の塗工が困難になり、積層体の外観不良も誘発されやすくなる。 [0020] The adhesive layer preferably has a thickness of 2πι-50 / ζ m. Since the adhesive used in the present invention is a so-called hot melt type adhesive that does not have tackiness at room temperature, When the thickness is less than 2 m, the adhesiveness at room temperature becomes insufficient, and the stress relaxation property between the laminated films due to the interposition of the adhesive may be insufficient. On the other hand, if it exceeds 50 m, it becomes difficult to apply the adhesive, and poor appearance of the laminate tends to be induced.
[0021] 前記コレステリック規則性を有する榭脂層が、重合性液晶化合物を含む液晶組成 物を重合して形成された非液晶性の榭脂層であることが、好まし 、。  [0021] Preferably, the resin layer having cholesteric regularity is a non-liquid crystalline resin layer formed by polymerizing a liquid crystal composition containing a polymerizable liquid crystal compound.
重合性液晶化合物を用いることにより榭脂層の配向性を高めることができる。  By using the polymerizable liquid crystal compound, the orientation of the resin layer can be enhanced.
[0022] 前記位相差フィルムの、式 I :Rth= { (nx+ny) Z2— nz} X d (式中、 nxは厚み方 向に垂直な方向であって最大の屈折率を与える方向の屈折率を表し、 nyは厚み方 向に垂直で nxに直交する方向の屈折率であり、 nzは厚み方向の屈折率を表し、 dは 膜厚を表す。）で表される厚み方向におけるレターデーシヨン Rth力 20〜一 100 Onmであること力 好ましい。力かる Rthは、位相差フィルムが材料としてスチレン系 榭脂を用いて 、るために容易に設定することができる。力かる Rthに設定された位相 差フィルムは、安価に得ることができ、より高価な液晶配向フィルムの性能を代替する ことができる。  [0022] In the retardation film, the formula I: Rth = {(nx + ny) Z2—nz} X d (where nx is a direction perpendicular to the thickness direction and giving the maximum refractive index) Ny is the refractive index in the direction perpendicular to the thickness direction and perpendicular to nx, nz is the refractive index in the thickness direction, and d is the film thickness. Decision Rth force 20 to 1 100 Onm is preferable. Powerful Rth can be set easily because the retardation film uses styrene-based resin as a material. Retardation films set at a high Rth can be obtained at low cost and can replace the performance of more expensive liquid crystal alignment films.
[0023] 本発明の輝度向上フィルムの製造方法は、前記偏光分離フィルムと前記位相差フ イルムとを、前記接着層を介して貼り合せる工程を含み、前記貼り合わせる工程にお V、て、前記偏光分離フィルムおよび前記位相差フィルムを 40°C〜110°Cの範囲でカロ 熱して貼り合わせることを特徴とする。  [0023] The method for producing a brightness enhancement film of the present invention includes a step of bonding the polarization separation film and the retardation film through the adhesive layer, and the bonding step V, The polarized light separating film and the retardation film are bonded together by heating in the range of 40 ° C to 110 ° C.
本発明の輝度向上フィルムにおいては、その構成要素である位相差フィルムがス チレン系榭脂層を有しているため、熱に対する寸法安定性が高められており、その結 果、前記温度範囲での熱接着が可能になっている。このホットメルト接着剤層により 前述のように打ち抜き加工性が良好に維持される。  In the brightness enhancement film of the present invention, the retardation film as a component thereof has a styrene-based resin layer, so that the dimensional stability against heat is enhanced, and as a result, in the above temperature range. Thermal bonding is possible. This hot melt adhesive layer maintains good punching processability as described above.
[0024] 本発明の液晶表示装置は、前記に記載のいずれかの輝度向上フィルムを有するこ とを特徴とする。  [0024] A liquid crystal display device of the present invention includes any one of the brightness enhancement films described above.
発明の効果  The invention's effect
[0025] 本発明に力かる輝度向上フィルムは、透明性、打ち抜き加工性が良好であり、しか も、製品コストの低減ィ匕が可能であり、各種表示装置に使用することにより表示装置 の輝度を向上するとともに、表示装置のコストを低減することができる。 図面の簡単な説明 [0025] The brightness enhancement film according to the present invention has good transparency and punching workability, and can reduce the product cost. By using it in various display devices, the brightness of the display device can be reduced. And the cost of the display device can be reduced. Brief Description of Drawings
[0026] [図 1]図 1は、本発明にかかる輝度向上フィルムを構成する偏光分離フィルムの構成 及び機能を示す説明図である。  [0026] FIG. 1 is an explanatory view showing the structure and function of a polarization separating film constituting the brightness enhancement film according to the present invention.
[図 2]図 2は、本発明の液晶表示装置の構成を示す分解斜視図である。  FIG. 2 is an exploded perspective view showing the configuration of the liquid crystal display device of the present invention.
発明を実施するための最良の形態  BEST MODE FOR CARRYING OUT THE INVENTION
[0027] 前述のように、本発明にかかる輝度向上フィルムは、スチレン系榭脂層を含む榭脂 フィルムを延伸してなる位相差フィルム、コレステリック規則性を有する榭脂層を含む 偏光分離フィルム、および前記位相差フィルムと前記偏光分離フィルムとの間に、温 度 23°Cにおける剪断貯蔵弾性率が l〜500MPaである組成物からなる接着層を含 むことを特徴とする。 [0027] As described above, the brightness enhancement film according to the present invention includes a retardation film formed by stretching a resin film including a styrene-based resin layer, a polarizing separation film including a resin layer having cholesteric regularity, And an adhesive layer made of a composition having a shear storage modulus of 1 to 500 MPa at a temperature of 23 ° C. is included between the retardation film and the polarization separation film.
力かる構成の輝度向上フィルムの各構成要素について、以下にさらに詳しく説明す る。  Each component of the brightness enhancement film having a strong structure will be described in more detail below.
[0028] (スチレン系榭脂層を少なくとも含むフィルムを延伸してなる位相差フィルム）  [0028] (A retardation film formed by stretching a film containing at least a styrene-based resin layer)
本発明における位相差フィルムを構成する「スチレン系榭脂層を含むフィルム」は、 従来提案されて 、る公知のスチレン系榭脂複層フィルムを用いることができる。一例 を挙げると、スチレン系榭脂からなるフィルム (a層）の両面に、他の熱可塑性榭脂か らなるフィルム (b層）を積層してなる複層フィルムを挙げることができる。  As the “film containing a styrene-based resin layer” constituting the retardation film in the present invention, a conventionally known styrene-based resin multilayer film can be used. For example, a multilayer film formed by laminating a film (b layer) made of another thermoplastic resin on both sides of a film (a layer) made of styrene-based resin can be exemplified.
[0029] 前記 a層を構成するスチレン系榭脂とは、スチレン構造を繰り返し単位の一部又は 全部として有する榭脂であり、具体的には、ポリスチレン、又は、スチレン、 ひ-メチル スチレン、 0-メチルスチレン、 p-メチルスチレン、 p-クロロスチレン、 p-ニトロスチレン、 P-アミノスチレン、 ρ-カルボキシスチレン、 p-フエ-ルスチレンなどのスチレン系単量 体と、エチレン、プロピレン、ブタジエン、イソプレン、（メタ)アクリロニトリル、 ひ-クロ口 アクリロニトリル、（メタ)アクリル酸メチル、（メタ)アクリル酸ェチル、（メタ)アクリル酸、無 水マレイン酸、酢酸ビニルなどのその他の単量体との共重合体などを挙げることがで きる。これらの中で、ポリスチレン又はスチレンと無水マレイン酸との共重合体を好適 に用いることができる。  [0029] The styrene-based resin constituting the layer a is a resin having a styrene structure as a part or all of the repeating units, specifically, polystyrene, styrene, trimethylstyrene, -Styrene monomers such as methyl styrene, p-methyl styrene, p-chloro styrene, p-nitro styrene, P-amino styrene, ρ-carboxy styrene, p-phenol styrene, and ethylene, propylene, butadiene, isoprene Copolymerization with other monomers such as, (meth) acrylonitrile, acrylic acrylonitrile, methyl (meth) acrylate, ethyl (meth) acrylate, (meth) acrylic acid, anhydrous maleic acid, vinyl acetate Examples include coalescence. Of these, polystyrene or a copolymer of styrene and maleic anhydride can be suitably used.
[0030] 本発明において、前記スチレン系榭脂の分子量は、使用目的に応じて適宜選定さ れる力 溶媒としてシクロへキサンを用いたゲル ·パーミエーシヨン，クロマトグラフィー で測定したポリイソプレン換算の重量平均分子量（Mw)で、通常 10, 000〜300, 0 00、好まし <は 15, 000〜250, 000、より好まし <は 20, 000〜200, 000である。ま た、このポリスチレン系榭脂は、ガラス転移温度が 120°C以上であることが好ましぐ 1 20〜200°Cであることがより好ましぐ 120〜140°Cであることがさらに好ましい。 [0030] In the present invention, the molecular weight of the styrene-based resin is appropriately selected according to the purpose of use. Gel permeation using cyclohexane as a solvent, chromatography The weight average molecular weight (Mw) in terms of polyisoprene measured in, usually 10,000 to 300,000, preferably <is 15,000 to 250,000, more preferably <is 20,000 to 200,000 is there. Further, the polystyrene-based resin preferably has a glass transition temperature of 120 ° C or higher 1 120-140 ° C, more preferably 120-140 ° C. .
[0031] 前記 b層を構成する他の熱可塑性榭脂は、厚さ lmmの試験片を用いて測定した全 光線透過率が 70%以上であることが好ましい。このような榭脂としては、例えば、脂 環式ォレフインポリマー、メタクリル酸エステル榭脂、ポリカーボネート、ポリエーテル スルホンなどを挙げることができる。これらの中で、脂環式ォレフインポリマーゃメタク リル酸エステル榭脂が好まし ヽ。 [0031] The other thermoplastic resin constituting the b layer preferably has a total light transmittance of 70% or more measured using a test piece having a thickness of 1 mm. Examples of such a resin include an alicyclic olefin polymer, a methacrylic acid ester resin, a polycarbonate, and a polyether sulfone. Of these, alicyclic olefin polymers are preferred to methacrylic acid ester resin.
[0032] 本発明に好適に用いられる脂環式ォレフインポリマーは、主鎖及び Zまたは側鎖に シクロアルカン構造を有する非晶性のォレフィンポリマーである。具体的には、（1)ノ ルボルネン系重合体、（2)単環の環状ォレフィン系重合体、（3)環状共役ジェン系 重合体、（4)ビニル脂環式炭化水素重合体、及びこれらの水素化物などが挙げられ る。これらの中でも、透明性や成形性の観点から、ノルボルネン系重合体がより好まし い。これらの脂環式ォレフインポリマーとしては、特開平 05— 310845号公報、特開 平 05— 097978号公報、米国特許第 6, 511, 756号公報に記載されているものが 挙げられる。  [0032] The alicyclic olefin polymer preferably used in the present invention is an amorphous olefin polymer having a cycloalkane structure in the main chain and Z or side chain. Specifically, (1) norbornene polymer, (2) monocyclic cyclic olefin polymer, (3) cyclic conjugation polymer, (4) vinyl alicyclic hydrocarbon polymer, and these Hydrides of the above. Among these, norbornene polymers are more preferable from the viewpoints of transparency and moldability. Examples of these alicyclic olefin polymers include those described in JP-A No. 05-310845, JP-A No. 05-097978, and US Pat. No. 6,511,756.
[0033] 本発明に好適に用いられるメタクリル酸エステル榭脂は、メタクリル酸エステルを主 成分とする重合体であり、メタクリル酸エステルの単独重合体や、メタクリル酸エステ ルとその他の単量体との共重合体が挙げられる、メタクリル酸エステルとしては、通常 、メタクリル酸アルキルが用いられる。共重合体とする場合は、メタクリル酸エステルと 共重合するその他の単量体としては、アクリル酸エステルや、芳香族ビニル化合物、 ビュルシアン化合物などが用いられる。  [0033] A methacrylic acid ester resin suitably used in the present invention is a polymer mainly composed of a methacrylic acid ester, and includes a homopolymer of a methacrylic acid ester, a methacrylic acid ester and other monomers. In general, alkyl methacrylate is used as the methacrylic acid ester. In the case of a copolymer, acrylic acid esters, aromatic vinyl compounds, burcyan compounds, etc. are used as other monomers copolymerized with methacrylic acid esters.
[0034] 前記 a層や b層には、必要に応じて酸化防止剤、熱安定剤、光安定剤、紫外線吸 収剤、帯電防止剤、分散剤、塩素捕捉剤、難燃剤、結晶化核剤、ブロッキング防止 剤、防曇剤、離型剤、顔料、有機又は無機の充填剤、中和剤、滑剤、分解剤、金属 不活性化剤、汚染防止剤、抗菌剤やその他の榭脂、熱可塑性エラストマ一などの公 知の添加剤を本発明の効果を損なわない範囲で添加することができる。 [0035] 本発明にお ヽて、前記スチレン系榭脂及び前記他の熱可塑性榭脂は、それらのガ ラス転移温度をそれぞれ Tg(a) (°C)及び Tg(b) (°C)としたとき、 Tg(a) >Tg(b) + 20°C の関係を満たすことが好ましい。このような関係を満たすことにより、延伸した際にス チレン系榭脂からなる a層に有効に光学的異方性を与えることができる。 [0034] The a layer and the b layer may be provided with an antioxidant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, a dispersant, a chlorine scavenger, a flame retardant, a crystallization nucleus as necessary. Agent, anti-blocking agent, anti-fogging agent, mold release agent, pigment, organic or inorganic filler, neutralizing agent, lubricant, decomposing agent, metal deactivator, antifouling agent, antibacterial agent and other grease, Known additives such as thermoplastic elastomers can be added within a range not impairing the effects of the present invention. [0035] In the present invention, the styrenic resin and the other thermoplastic resin have glass transition temperatures of Tg (a) (° C) and Tg (b) (° C), respectively. It is preferable that the relationship of Tg (a)> Tg (b) + 20 ° C is satisfied. By satisfying such a relationship, optical anisotropy can be effectively imparted to the a layer made of styrene-based resin when stretched.
[0036] a層の材料である前記スチレン系榭脂及び b層の材料である他の熱可塑性榭脂を 積層して、スチレン系榭脂複層フィルムに成形する方法は、特に限定されないが、共 押出 Tダイ法、共押出インフレーション法、共押出ラミネーシヨン法等の共押出による 成形方法、ドライラミネーシヨン等のフィルムラミネーシヨン成形方法、及びコーティン グ成形方法などの公知の方法が適宜利用され得る。中でも、製造効率や、フィルム 中に溶剤などの揮発性成分を残留させな 、と 、う観点から、共押出による成形方法 が好ましい。押出し温度は、使用する前記スチレン系榭脂、及び前記他の熱可塑性 榭脂の種類に応じて適宜選択され得る。  [0036] The method of laminating the styrene-based resin that is the material of the a layer and the other thermoplastic resin that is the material of the b-layer to form a styrene-based resin multilayer film is not particularly limited, Known methods such as coextrusion T-die method, coextrusion inflation method, coextrusion molding method such as coextrusion lamination method, film lamination molding method such as dry lamination, and coating molding method can be used as appropriate. . Among these, a molding method by coextrusion is preferable from the viewpoint of manufacturing efficiency and that volatile components such as a solvent do not remain in the film. The extrusion temperature can be appropriately selected according to the type of the styrene-based resin used and the other thermoplastic resin.
[0037] 本発明に用いるスチレン系榭脂複層フィルムは、前記 a層の両面に、前記 b層を積 層してなる。 a層と b層の間には、接着層や粘着層を設けることができる力 a層と b層 とを直接に積層させる（つまり、 b層 Za層 Zb層の 3層構成の積層体とする）ことが好 ましい。また、このスチレン系榭脂複層フィルムにおいて、前記 a層及びその両面に 積層された b層の平均厚みは特に制限はないが、好ましくはそれぞれ 10〜300 μ m 及び 10〜400 μ mとすることができる。  [0037] The styrene-based resin multilayer film used in the present invention is formed by stacking the b layer on both sides of the a layer. The force that can provide an adhesive layer or adhesive layer between the a layer and the b layer Laminate the a layer and the b layer directly (that is, a layered structure of b layer Za layer Zb layer) ) Is preferred. Moreover, in this styrene-based resin multilayer film, the average thickness of the a layer and the b layer laminated on both sides thereof is not particularly limited, but preferably 10 to 300 μm and 10 to 400 μm, respectively. be able to.
[0038] 前記スチレン系榭脂複層フィルムを延伸することにより本発明の輝度向上フィルム を構成する位相差フィルムを得ることができる。この延伸複層フィルムは、 a層の延伸 により設けられた A層、及び b層の延伸により設けられた B層を含むことができる。この 延伸複層フィルム (位相差フィルム）は、前記スチレン系榭脂複層フィルムの b層 Za 層 Zb層の 3層構造の積層体を延伸してなり、 B層 ZA層 ZB層の 3層構造の延伸フ イルムであることが好ましい。この延伸は、好ましくは一軸延伸又は斜め延伸により行 うことができ、さらに好ましくはテンターによる一軸延伸又は斜め延伸により行うことが できる。  [0038] A retardation film constituting the brightness enhancement film of the present invention can be obtained by stretching the styrene-based resin multilayer film. This stretched multilayer film can include a layer A provided by stretching a layer and a layer B provided by stretching b layer. This stretched multilayer film (retardation film) is formed by stretching a layered structure of b layer Za layer Zb layer of the above-mentioned styrene-based resin multilayer film, and B layer ZA layer ZB layer three layer structure The stretched film is preferably used. This stretching can be preferably performed by uniaxial stretching or oblique stretching, and more preferably by uniaxial stretching or oblique stretching by a tenter.
[0039] この延伸複層フィルム (位相差フィルム）にお ヽては、前記 A層と前記 B層の間の層 間剥離強度が、 1. 3NZ25mm以上であることが好ましい。ここで、層間剥離強度は 、 JIS K— 6854— 2に準拠して、引張速度 lOOmmZ分で 180度剥離により測定さ れた値である。このような層間剥離強度を有することにより、耐久性の高い延伸複層 フィルムとすることができる。 [0039] In the stretched multilayer film (retardation film), the interlaminar peel strength between the A layer and the B layer is preferably 1.3 NZ25 mm or more. Here, the delamination strength is According to JIS K-6854-2, the value was measured by 180 ° peeling at a tensile speed of lOOmmZ. By having such delamination strength, a highly durable stretched multilayer film can be obtained.
[0040] また、この延伸複層フィルム (位相差フィルム）は、好ましくは、全光線透過率が 92 %以上、且つ、ヘーズが 5%以下である。このように高い全光線透過率および低いへ ーズを有することにより、位相差フィルムとして良好な特性を有するものとなる。  [0040] The stretched multilayer film (retardation film) preferably has a total light transmittance of 92% or more and a haze of 5% or less. By having such a high total light transmittance and a low haze, the retardation film has good characteristics.
[0041] 本発明に用いる位相差フィルムとしては、前記 Rthを、式 I :Rth= { (nx+ny) /2 nz} X d (式中、 nxは厚み方向に垂直な方向であって最大の屈折率を与える方向 の屈折率を表し、 nyは厚み方向に垂直で nxに直交する方向の屈折率であり、 nzは 厚み方向の屈折率を表し、 dは膜厚を表す。）で表わした場合、— 20〜― lOOOnm であることが好ましぐ 50〜一 300nmであることがより好まし!/、。  [0041] As the retardation film used in the present invention, the Rth is represented by the formula I: Rth = {(nx + ny) / 2nz} Xd (wherein nx is a direction perpendicular to the thickness direction and is the maximum Ny represents the refractive index in the direction perpendicular to the thickness direction and perpendicular to nx, nz represents the refractive index in the thickness direction, and d represents the film thickness). In the case of -20 to lOOOnm, 50 to 1 300 nm is more preferable!
[0042] この位相差フィルムの厚み方向のレターデーシヨン Rthの値を前記負の範囲にする ことにより、この位相差フィルムに、従来の輝度向上フィルムに使用されていた液晶配 向フィルムの代替として十分な光学特性を持たせることができる。なお、前記厚み方 向のレターデーシヨン Rthは、位相差フィルムを幅方向で等間隔に測定し、各測定点 における厚み方向のレターデーシヨン値の平均値として表される。  [0042] By making the retardation Rth value in the thickness direction of the retardation film in the negative range, this retardation film can be used as an alternative to the liquid crystal orientation film used in the conventional brightness enhancement film. Sufficient optical characteristics can be provided. The thickness direction letter-thickness Rth is expressed as an average value of the thickness direction letter-decision values measured at equal intervals in the width direction of the retardation film.
[0043] 本発明に用いる位相差フィルムとして、入射光に対して 1Z4波長の位相差を与え るものであることがより好ましい。通常、可視光線の中心波長、例えば 550nm付近に おいて式 II :Re= (nx— ny) X d (式中、 nxは厚み方向に垂直な方向であって最大 の屈折率を与える方向の屈折率を表し、 nyは厚み方向に垂直で nxに直交する方向 の屈折率を表し、 dは膜厚を表す。）で表される面内方向のレターデーシヨン Reが 1 Z4波長の位相差を与えるものを 1Z4波長板と称している。  [0043] It is more preferable that the retardation film used in the present invention gives a phase difference of 1Z4 wavelength to incident light. Usually, at the center wavelength of visible light, for example, around 550 nm, the formula II: Re = (nx—ny) X d (where nx is the direction perpendicular to the thickness direction and gives the maximum refractive index) Ny represents the refractive index in the direction perpendicular to the thickness direction and perpendicular to nx, and d represents the film thickness.) The in-plane direction letter Re represented by 1) represents the phase difference of 1 Z4 wavelength. What we give is called a 1Z4 waveplate.
[0044] 本発明においては、前記面内方向のレターデーシヨン Reが、可視光線の中心波長 である波長 550nmにおいて波長の 1Z4であることが好ましぐ波長 410〜660nmを 含む可視光領域のどの波長でもほぼ 1Z4波長であることがより好ましい。ほぼ 1Z4 とは、 0. 15〜0. 40、好ましくは、 0. 18〜0. 36、さらに好ましくは、 0. 20〜0. 30、 の範囲であることを意味する。なお、前記面内方向のレターデーシヨン Reは、位相差 フィルムを幅方向で等間隔に測定し、各測定点における面内方向のレターデーショ ン値の平均値として表される。 [0044] In the present invention, the in-plane direction letter Re is preferably 1Z4 of a wavelength at a wavelength of 550 nm which is the central wavelength of visible light. It is more preferable that the wavelength is approximately 1Z4. About 1Z4 means that it is in the range of 0.15 to 0.40, preferably 0.18 to 0.36, and more preferably 0.20 to 0.30. In addition, the in-plane direction letter Re is measured at equal intervals in the width direction of the retardation film, and the in-plane direction letter distortion at each measurement point. Expressed as the average of the values.
[0045] また、本発明に用いる位相差フィルムとして、波長 400〜700nmの光で測定した前 記 A層及び前記 B層の面内方向のレターデーシヨンの総和をそれぞれ Re (A)及び R e (B)としたとき、式（1)及び式（2)を満たし、且つ、波長 400〜700nmの光で測定し た面内方向のレターデーシヨンを Re、厚み方向のレターデーシヨンを Rthとしたとき、 式（3)及び式 (4)を満たすものであることが特に好ま 、。  [0045] In addition, as the retardation film used in the present invention, the sum of the in-plane direction letterings of the A layer and the B layer measured with light having a wavelength of 400 to 700 nm is represented by Re (A) and Re, respectively. In the case of (B), Re is the in-plane direction letter measurement that satisfies the equations (1) and (2) and is measured with light having a wavelength of 400 to 700 nm, and Rth is the letter direction thickness direction. In this case, it is particularly preferable that the expression (3) and the expression (4) are satisfied.
式 (1) : | Re (A) I > | Re (B) |  Formula (1): | Re (A) I> | Re (B) |
式（2)： I Re (B) I < 20nm  Formula (2): I Re (B) I <20 nm
式（3)： Rth/ I Re I≤— 0. 5  Formula (3): Rth / I Re I≤— 0.5
式（4)： Rth< 0  Formula (4): Rth <0
[0046] Re (A)、 Re (B)、 Re及び Rth力これらの関係を満たすことにより、この延伸複層フィ ルムは、位相差フィルムとして、良好な光学的特性を得ることができる。  [0046] By satisfying these relationships, Re (A), Re (B), Re and Rth forces, this stretched multilayer film can obtain good optical characteristics as a retardation film.
[0047] 本発明に用いる位相差フィルムは、延伸温度や延伸倍率等の延伸条件を適宜調 整すること〖こより製造することができる。延伸温度は、前記 Tg(a)—10 (°C)〜前記 Tg( a) + 20 (°C)が好ましく、前記 Tg(a) - 5 (°C)〜前記 Tg(a) + 15 (°C)の範囲であること 力 り好ましい。延伸倍率は、 1.05〜30倍が好ましぐ 1.1〜10倍であることがより好 ましい。延伸温度や延伸倍率が、上記範囲を外れると、配向が不十分で屈折率異方 性、ひいてはレターデーシヨンの発現が不十分になったり、積層体が破断したりする おそれがある。  [0047] The retardation film used in the present invention can be produced by appropriately adjusting stretching conditions such as a stretching temperature and a stretching ratio. The stretching temperature is preferably Tg (a) -10 (° C) to Tg (a) +20 (° C), Tg (a) -5 (° C) to Tg (a) +15 ( A temperature range of ° C) is particularly preferable. The draw ratio is preferably 1.05 to 30 times, more preferably 1.1 to 10 times. If the stretching temperature or stretching ratio is out of the above range, the orientation may be insufficient and the refractive index anisotropy, and thus the letter expression may be insufficient, or the laminate may be broken.
[0048] 本発明に用いる位相差フィルムは、その少なくとも片面に直径 0. 001-0. 1 m の突起があり、該突起の個数が 50〜500個 Ζ30 /ζ πιであることが好ましい。このよう な突起を有することにより、延伸複層フィルム表面の滑り性が向上し、延伸複層フィル ムのハンドリング性が良くなる。  [0048] The retardation film used in the present invention preferably has protrusions having a diameter of 0.001 to 0.1 m on at least one side, and the number of protrusions is 50 to 500 Ζ30 / ζ πι. By having such protrusions, the sliding property of the stretched multilayer film surface is improved, and the handling properties of the stretched multilayer film are improved.
[0049] (コレステリック規則性を有する榭脂層を少なくとも含む偏光分離フィルム）  [0049] (Polarized light-separating film including at least a resin layer having cholesteric regularity)
本発明の構成要素である偏光分離フィルムはコレステリック規則性を有する榭脂層 を含む。本発明においては、コレステリック規則性を有する榭脂層が、重合性液晶化 合物を含む液晶組成物を重合して形成された非液晶性の榭脂層であることが好まし い。 [0050] 本発明に用いる偏光分離フィルムが有するコレステリック規則性を有する榭脂層を 構成する重合性液晶化合物として、例えば、下記一般式（1)で表される重合性液晶 化合物を挙げることができる。 The polarized light separation film which is a constituent element of the present invention includes a resin layer having cholesteric regularity. In the present invention, the resin layer having cholesteric regularity is preferably a non-liquid crystalline resin layer formed by polymerizing a liquid crystal composition containing a polymerizable liquid crystal compound. [0050] Examples of the polymerizable liquid crystal compound constituting the resin layer having the cholesteric regularity of the polarization separation film used in the present invention include a polymerizable liquid crystal compound represented by the following general formula (1). .
R3 - C3 - D3 - C5 - M - C6 - D4 - C4 R4 (1) R 3 -C 3 -D 3 -C 5 -M-C 6 -D 4 -C 4 R 4 (1)
(式中、 R3及び R4は反応性基であり、それぞれ独立して (メタ)アクリル基、（チォ)ェポ キシ基、ォキセタン基、チエタ-ル基、アジリジ-ル基、ピロール基、ビュル基、ァリル 基、フマレート基、シンナモイル基、ォキサゾリン基、メルカプト基、イソ (チォ)シァネ ート基、アミノ基、ヒドロキシル基、カルボキシル基、及びアルコキシシリル基力もなる 群より選択される基を表す。 D3及び D4は単結合、炭素原子数 1〜20個の直鎖状又 は分岐鎖状のアルキル基、及び炭素原子数 1〜20個の直鎖状又は分岐鎖状のアル キレンオキサイド基力 なる群より選択される基を表す。 c3〜c6は単結合、—O—、 — S 、 一 S— S 、 一 CO 、 一 CS 、 一 OCO 、 一 CH —、 一 OCH —、 一 C=N (In the formula, R 3 and R 4 are reactive groups, and each independently represents a (meth) acryl group, a (thio) epoxy group, an oxetane group, a thietal group, an aziridyl group, a pyrrole group, Represents a group selected from the group consisting of a buyl group, an aryl group, a fumarate group, a cinnamoyl group, an oxazoline group, a mercapto group, an iso (thio) cyanate group, an amino group, a hydroxyl group, a carboxyl group, and an alkoxysilyl group. D 3 and D 4 are a single bond, a linear or branched alkyl group having 1 to 20 carbon atoms, and a linear or branched alkylene oxide having 1 to 20 carbon atoms. C 3 to c 6 are a single bond, —O—, — S, 1 S—S, 1 CO, 1 CS, 1 OCO, 1 CH —, 1 OCH —, C = N
2 2  twenty two
一 N = C 、 一 NHCO 、 一 OCOO 、 一 CH COO—、及び一 CH OCO 力、ら  One N = C, one NHCO, one OCOO, one CH COO—, and one CH OCO force, etc.
2 2  twenty two
なる群より選択される基を表す。 Mはメソゲン基を表し、具体的には、非置換又はハ ロゲン原子、ヒドロキシル基、カルボキシル基、シァノ基、アミノ基、炭素原子数 1〜： L0 個の直鎖状又は分岐状のアルキル基、ハロゲンィヒアルキル基で 1つ以上置換されて いてもよい、ァゾメチン類、ァゾキシ類、ビフエ-ル類、ターフェ-ル類、ナフタレン類 、アントラセン類、シァノビフエ-ル類、シァノフエ-ルエステル類、安息香酸エステル 類、シクロへキサンカルボン酸フエ-ルエステル類、シァノフエ-ルシクロへキサン類 、シァノ置換フエ-ルビリミジン類、アルコキシ置換フエ-ルビリミジン類、フエ-ルジ ォキサン類、トラン類、ァルケ-ルシクロへキシルベンゾ-トリル類の群から選択され た 2〜4個の骨格を— O—、— S―、— S— S―、— CO—、— CS―、— OCO—、 - CH 一、 一 OCH —、 一 C=N— N = C 、 一 NHCO 、 一 OCOO 、 一 CH CO Represents a group selected from the group consisting of M represents a mesogenic group, specifically, an unsubstituted or halogen atom, a hydroxyl group, a carboxyl group, a cyano group, an amino group, a linear or branched alkyl group having 1 to L0 carbon atoms, Arzomethines, azoxys, biphenyls, terphels, naphthalenes, anthracenes, cyanobiphenols, cyanophyl esters, benzoic acid, optionally substituted with one or more halogenoalkyl groups Esters, cyclohexanecarboxylic acid ester esters, cyanophenylcyclohexanes, cyano-substituted ferrobirimidines, alkoxy-substituted ferrobirimidines, ferrodioxanes, tolans, alkenylcyclohexylbenzo-tolyl 2 to 4 skeletons selected from the group of —O—, —S—, —S—S—, —CO—, —CS—, —OCO—, -CH H —, 1 C = N— N = C, 1 NHCO, 1 OCOO, 1 CH CO
2 2 22 2 2
O—、及び CH OCO 等の結合基によって結合されて形成される。） It is formed by bonding with bonding groups such as O— and CH 2 OCO 3. )
2  2
[0051] 本発明にお 、て、前記重合性液晶化合物は非対称構造であることが好ま 、。ここ で非対称構造とは、一般式（1)において、メソゲン基 Mを中心として R3— C3— D3— C 5—と— C6— D4— C4— R4が異なる構造のことをいう。該液晶性化合物として、非対称 構造のものを用いることにより、配向均一性をより高めることができる。 [0052] 前記重合性液晶化合物は、その Δ η値 (複屈折値）が 0. 18以上、好ましくは 0. 22 以上である。 Δ η値が 0. 30以上の化合物を用いると、紫外線吸収スペクトルの長波 長側の吸収端が可視域に及ぶ場合があるが、該スペクトルの吸収端が可視域に及 んでも所望する光学的性能に悪影響を及ぼさない限り、使用可能である。このような 高い Δ η値を有することにより、高い光学的性能を有する円偏光分離フィルムを与え ることがでさる。 [0051] In the present invention, the polymerizable liquid crystal compound preferably has an asymmetric structure. Here, the asymmetric structure is a structure in which R 3 — C 3 — D 3 — C 5— and — C 6 — D 4 — C 4 — R 4 are different in the general formula (1) with the mesogenic group M as the center. Say. By using a liquid crystal compound having an asymmetric structure, alignment uniformity can be further improved. [0052] The polymerizable liquid crystal compound has a Δη value (birefringence value) of 0.18 or more, preferably 0.22 or more. When a compound with a Δη value of 0.30 or more is used, the absorption edge on the long wavelength side of the ultraviolet absorption spectrum may extend to the visible range, but the desired optical properties may be achieved even if the absorption edge of the spectrum extends to the visible range. It can be used as long as the performance is not adversely affected. By having such a high Δη value, a circularly polarized light separating film having high optical performance can be provided.
[0053] 前記重合性液晶化合物は、 1分子中に少なくとも 2つ以上の反応性基を有すること が好ましい。前記反応性基としては、具体的にはエポキシ基、チォエポキシ基、ォキ セタン基、チエタ-ル基、アジリジ-ル基、ピロール基、フマレート基、シンナモイル基 、イソシァネート基、イソチオシァネート基、アミノ基、ヒドロキシル基、カルボキシル基 、アルコキシシリル基、メルカプト基、ビュル基、ァリル基、メタクリル基、アクリル基等 が挙げられる。これらの反応性基を有することにより、本発明に用いるコレステリック榭 脂組成物を硬化させた際に、安定した硬化物を得ることができる。 1分子中に反応性 基が 1つ以下の化合物を用いると、コレステリック樹脂組成物を硬化させた際に、架 橋した硬化物が得られな 、ため実用に耐えうる膜強度が得られな 、。後述する架橋 剤を使用した場合でも、膜強度が不足してしまい実用は困難である。実用に耐えうる 膜強度とは鉛筆硬度 (JIS Κ5400)で ΗΒ以上、好ましくは Η以上である。 ΗΒより低 いと傷がつきやすくハンドリング性に欠けてしまう。好ましい鉛筆硬度の上限は、光学 的性能や耐久性試験に悪影響を及ぼさなければ特に限定されない。  [0053] The polymerizable liquid crystal compound preferably has at least two reactive groups in one molecule. Specific examples of the reactive group include an epoxy group, a thioepoxy group, an oxetane group, a thietal group, an aziridyl group, a pyrrole group, a fumarate group, a cinnamoyl group, an isocyanate group, an isothiocyanate group, Amino group, hydroxyl group, carboxyl group, alkoxysilyl group, mercapto group, bur group, aryl group, methacryl group, acrylic group and the like can be mentioned. By having these reactive groups, a stable cured product can be obtained when the cholesteric resin composition used in the present invention is cured. When a compound having 1 or less reactive group in one molecule is used, when the cholesteric resin composition is cured, a crosslinked cured product cannot be obtained, so that a film strength that can withstand practical use cannot be obtained. . Even when a cross-linking agent described later is used, the film strength is insufficient and practical use is difficult. The film strength that can withstand practical use is not less than 、, preferably not less than で in terms of pencil hardness (JIS Κ5400). If it is lower than ΗΒ, it is easily scratched and lacks handling. The upper limit of the preferred pencil hardness is not particularly limited as long as it does not adversely affect the optical performance and durability test.
[0054] 本発明に用いられるコレステリック規則性を有する榭脂層を構成する液晶組成物は 、必要に応じてさらに他の任意成分を含有することができる。当該他の任意成分とし ては、架橋剤、光重合開始剤、カイラル剤、溶媒、ポットライフ向上のための重合禁 止剤、耐久性向上のための酸ィ匕防止剤、紫外線吸収剤、光安定化剤等を挙げること ができる。これらの任意成分は、所望する光学的性能を低下させない範囲で添加で きる。 [0054] The liquid crystal composition that constitutes the cholesteric regularized resin layer used in the present invention may further contain other optional components as necessary. Other optional components include cross-linking agents, photopolymerization initiators, chiral agents, solvents, polymerization inhibitors for improving pot life, anti-oxidation agents for improving durability, UV absorbers, light Stabilizers can be mentioned. These optional components can be added as long as the desired optical performance is not deteriorated.
[0055] 本発明に用いられるコレステリック規則性を有する榭脂層を構成する液晶組成物の 製造方法は、特に限定されず、上記必須成分及び任意成分を混合することにより製 造することができる。 [0056] 本発明の輝度向上フィルムの構成要素である偏光分離フィルムは、前記液晶組成 物を透明榭脂基材に塗布し、少なくとも 1回の、加温及び Z又は光照射により硬化し てなる。 [0055] A method for producing a liquid crystal composition constituting the cholesteric regularized resin layer used in the present invention is not particularly limited, and can be produced by mixing the above essential components and optional components. [0056] The polarized light separation film as a component of the brightness enhancement film of the present invention is obtained by applying the liquid crystal composition to a transparent resin base material and curing it by at least one heating and Z or light irradiation. .
[0057] 前記透明榭脂基材は、特に限定されず lmm厚で全光透過率 80%以上の基材を 使用することができる。具体的には、脂環式ォレフインポリマー、ポリエチレンやポリプ ロピレンなどの鎖状ォレフィンポリマー、トリァセチルセルロース、ポリビュルアルコー ル、ポリイミド、ポリアリレート、ポリエステル、ポリカーボネート、ポリスルホン、ポリエー テルスルホン、変性アクリルポリマー、エポキシ榭脂などの合成樹脂からなる単層又 は積層のフィルムが挙げられる。これらの中でも、脂環式ォレフインポリマー又は鎖状 ォレフィンポリマーが好ましぐ透明性、低吸湿性、寸法安定性、軽量性などの観点 から、脂環式ォレフインポリマーが特に好ましい。  [0057] The transparent resin base material is not particularly limited, and a base material having an lmm thickness and a total light transmittance of 80% or more can be used. Specific examples include cycloaliphatic olefin polymers, chain olefin polymers such as polyethylene and polypropylene, triacetyl cellulose, polybutyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, and modified acrylic. A monolayer or laminated film made of a synthetic resin such as a polymer or epoxy resin can be used. Among these, alicyclic olefin polymers are particularly preferable from the viewpoints of transparency, low hygroscopicity, dimensional stability, light weight and the like, which are preferable for alicyclic olefin polymers or chain olefin polymers.
[0058] 前記透明榭脂基材は、必要に応じて、配向膜を有することができる。配向膜を有す ることにより、その上に塗布されたコレステリック規則性を有する榭脂層を構成する液 晶組成物を所望の方向に配向させることができる。配向膜は、基材表面上に、必要 に応じてコロナ放電処理等を施した後、セルロース、シランカップリング剤、ポリイミド、 ポリアミド、ポリビュルアルコール、エポキシアタリレート、シラノールオリゴマー、ポリア クリロ-トリル、フエノール榭脂、ポリオキサゾール、環化ポリイソプレンなどを水又は溶 剤に溶解させた溶液等を、リバースグラビアコーティング、ダイレクトグラビアコーティ ング、ダイコーティング、バーコーティング等の公知の方法を用いて塗布し、乾燥させ 、その後、乾燥塗膜にラビング処理を施すことにより形成することができる。配向膜の 平均厚みは、所望する榭脂層の配向均一性が得られる厚みであれば特に制限され ないが、 0. 001〜5 /ζ πιであることが好ましぐ 0. 01〜2 /ζ πιであることがさらに好ま しい。  [0058] The transparent resin base material may have an alignment film, if necessary. By having the alignment film, it is possible to align the liquid crystal composition constituting the resin layer having cholesteric regularity applied thereon in a desired direction. The alignment film is subjected to a corona discharge treatment or the like on the substrate surface as necessary, and then cellulose, silane coupling agent, polyimide, polyamide, polybutyl alcohol, epoxy acrylate, silanol oligomer, polyacrylo-tolyl, A solution prepared by dissolving phenol resin, polyoxazole, cyclized polyisoprene or the like in water or a solvent is applied using a known method such as reverse gravure coating, direct gravure coating, die coating, or bar coating. It can be formed by drying and then rubbing the dried coating film. The average thickness of the alignment film is not particularly limited as long as the desired uniformity of alignment of the resin layer can be obtained, but is preferably 0.001 to 5 / ζ πι. More preferably, ζ πι.
[0059] 前記透明榭脂基材へのコレステリック規則性を有する榭脂層を構成する液晶組成 物の塗布は、リバースグラビアコーティング、ダイレクトグラビアコーティング、ダイコー ティング、バーコーティング等の公知の方法により行うことができる。  [0059] The liquid crystal composition constituting the resin layer having cholesteric regularity is applied to the transparent resin base material by a known method such as reverse gravure coating, direct gravure coating, die coating, bar coating, or the like. Can do.
[0060] 前記塗布により得られた塗布層を硬化する前に、必要に応じて、配向処理を施すこ とができる。配向処理は、例えば塗布層を 50〜150°Cで 0. 5〜： LO分間加温すること により行うことができる。当該配向処理を施すことにより、コレステリック規則性を有す る榭脂層を構成する液晶組成物を良好に配向させることができる。 [0060] Prior to curing the coating layer obtained by the coating, an orientation treatment may be performed as necessary. For orientation treatment, for example, the coating layer is heated at 50 to 150 ° C for 0.5 to: LO minutes. Can be performed. By performing the alignment treatment, the liquid crystal composition constituting the resin layer having cholesteric regularity can be aligned well.
[0061] 必要に応じて配向処理を施した後、コレステリック規則性を有する榭脂層を構成す る液晶組成物を硬化させることにより、コレステリック規則性を有する榭脂層を有する 偏光分離フィルムを得ることができる。前記硬化の工程は、少なくとも 1回、の加温及 び Z又は光照射により行うことができる。加温条件は、具体的には、例えば、温度 40 〜140°C、時間は 1秒〜 3分とすることができる。本発明において光照射に用いる光 とは、可視光のみならず紫外線及びその他の電磁波をも含む。光照射は、具体的に は、例えば波長 200〜500nmの光を 0. 01秒〜 3分照射することにより行うことがで きる。また、例えば、 0. 01〜50mjZcm2の微弱な紫外線照射と加温とを複数回交 互に繰り返し、反射帯域の広 、偏光分離フィルムとすることもできる。 [0061] After performing an alignment treatment as necessary, the liquid crystal composition constituting the cholesteric regularity resin layer is cured to obtain a polarization separation film having a cholesteric regularity resin layer. be able to. The curing step can be performed by at least one heating and Z or light irradiation. Specifically, for example, the heating condition may be a temperature of 40 to 140 ° C. and a time of 1 second to 3 minutes. In the present invention, the light used for light irradiation includes not only visible light but also ultraviolet rays and other electromagnetic waves. Specifically, the light irradiation can be performed by, for example, irradiating light having a wavelength of 200 to 500 nm for 0.01 seconds to 3 minutes. Further, for example, it is possible to obtain a polarized light separation film having a wide reflection band by repeating a weak ultraviolet irradiation of 0.01 to 50 mjZcm 2 and heating a plurality of times alternately.
[0062] 前記透明榭脂基材上へのコレステリック規則性を有する榭脂層を構成する液晶組 成物の塗布及び硬化の工程は、 1回に限られず、塗布及び硬化を複数回繰り返し 2 層以上の榭脂層を形成することもできる。  [0062] The steps of applying and curing the liquid crystal composition constituting the resin layer having cholesteric regularity on the transparent resin base material are not limited to once, and the application and curing are repeated two or more times. It is also possible to form the above-mentioned resin layer.
[0063] 本発明の輝度向上フィルムを構成する偏光分離フィルムにおいて、コレステリック規 則性を有する榭脂層の乾燥膜厚は好ましくは 3. 0 /ζ πι〜10. O /z m、より好ましくは 3 . 5〜8. O /z mである。 3. O /z mより薄! /、と反射率力 下してしま!/、、 10. O /z mより厚 いと、榭脂層に対して斜め方向から観察した時に着色してしまうため、それぞれ好ま しくない。  [0063] In the polarization separation film constituting the brightness enhancement film of the present invention, the dry film thickness of the resin layer having cholesteric regularity is preferably 3.0 / ζ πι to 10. O / zm, more preferably 3 5-8. O / zm. 3. It is thinner than O / zm! /, And the reflectivity is lowered! /, 10. If it is thicker than O / zm, it will be colored when observed from an oblique direction with respect to the resin layer. I don't like it.
[0064] (偏光分離フィルム）  [0064] (Polarized light separation film)
図 1は、本発明の輝度向上フィルムに用 ヽる偏光分離フィルム 1を模式的に表した ものである。図 1では、基材 2の上に配向膜 3が積層され、配向膜 3の上にコレステリッ ク榭脂層 4が積層されている。コレステリック樹脂層 4は、ピッチが異なる四つの層（ピ ツチが PO、 Pl、 P2、 P3の各層）からなつている。図 1では、ピッチ p力 PO、 Pl、 P2、 P3の順に広くなつている。なお、図 1では、各コレステリック樹脂層 PO、 Pl、 P2及び P3の 1周期分のカイラル構造しか図示していないが、カイラル構造は 2周期以上にな つていてもよい。  FIG. 1 schematically shows a polarized light separation film 1 used in the brightness enhancement film of the present invention. In FIG. 1, an alignment film 3 is laminated on a substrate 2, and a cholesteric resin layer 4 is laminated on the alignment film 3. The cholesteric resin layer 4 is composed of four layers having different pitches (the pitches are PO, Pl, P2, and P3 layers). In Fig. 1, the pitch p force increases in the order of PO, Pl, P2, P3. Although FIG. 1 shows only a chiral structure for one period of each cholesteric resin layer PO, Pl, P2, and P3, the chiral structure may have two or more periods.
[0065] この偏光分離フィルム 1のコレステリック樹脂層 4に、光が入射すると、特定波長領 域の左回り又は右回りの何れかの円偏光のみが反射される。反射された円偏光以外 の光は透過する。偏光分離フィルムのコレステリック樹脂層 4に入射角 θ 1で入射した 白色光は、コレステリック樹脂層 4表面で屈折して屈折角 Θ 2でコレステリック樹脂層 4 内に入射し、波長えに対応したピッチ Pを持つコレステリック樹脂層 4の中で一方の 円偏光が反射角 Θ 2で反射し、コレステリック樹脂層 4表面で屈折して出射角 θ 1で 出射する。屈折はスネルの法則に従って行われる。 [0065] When light is incident on the cholesteric resin layer 4 of the polarization separating film 1, Only circularly polarized light that is either counter-clockwise or clockwise is reflected. Light other than the reflected circularly polarized light is transmitted. White light incident on the cholesteric resin layer 4 of the polarized light separation film at an incident angle θ 1 is refracted on the surface of the cholesteric resin layer 4 and incident on the cholesteric resin layer 4 at a refraction angle Θ 2, and the pitch P corresponds to the wavelength. In the cholesteric resin layer 4 having one, one circularly polarized light is reflected at the reflection angle Θ 2, refracted on the surface of the cholesteric resin layer 4 and emitted at the emission angle θ 1. Refraction is performed according to Snell's law.
[0066] 図 1に示すように、カイラル構造において分子軸が捩れる時の回転軸を表す螺旋 軸 5と、コレステリック樹脂層 4の法線とが平行である場合、カイラル構造のピッチ (長 さ) pと反射される円偏光の波長えとは、下記式 (2)の関係を有する。 [0066] As shown in FIG. 1, when the helical axis 5 representing the rotation axis when the molecular axis is twisted in the chiral structure and the normal line of the cholesteric resin layer 4 are parallel, the pitch (length) of the chiral structure ) The wavelength of the circularly polarized light reflected by p has the relationship of the following formula (2).
λ =n X p X cos θ 2 (2)  λ = n X p X cos θ 2 (2)
ここで、 n= (ne+no) Z2 (式中、 noは重合性液晶化合物の短軸方向の屈折率を 表し、 neは重合性液晶化合物の長軸方向の屈折率を表す。）である。  Here, n = (ne + no) Z2 (wherein, no represents the refractive index in the minor axis direction of the polymerizable liquid crystal compound, and ne represents the refractive index in the major axis direction of the polymerizable liquid crystal compound). .
従って、ピッチ pのコレステリック樹脂層 4で反射される円偏光の反射帯域は、下記 式（3)で表される。  Therefore, the reflection band of circularly polarized light reflected by the cholesteric resin layer 4 with the pitch p is expressed by the following formula (3).
no X p X cos θ 2≤ λ≤ne X p X cos θ 2 (3)  no X p X cos θ 2≤ λ≤ne X p X cos θ 2 (3)
[0067] (接着層） [0067] (Adhesive layer)
本発明の輝度向上フィルムを構成する接着層は、前記位相差フィルムと偏光分離 フィルムとを接着しており、本発明の輝度向上フィルムの打ち抜き加工性を良好に維 持するために重要な役目を果たしている部材である。その特徴は、温度 23°Cにおけ る剪断貯蔵弾性率が l〜500MPaである組成物力も構成されている点にある。  The adhesive layer constituting the brightness enhancement film of the present invention adheres the retardation film and the polarization separation film, and plays an important role in favorably maintaining the punchability of the brightness enhancement film of the present invention. It is a member that plays. The feature is that the compositional force with a shear storage modulus at a temperature of 23 ° C is 1 to 500 MPa.
[0068] (温度 23°Cにおける剪断貯蔵弾性率が l〜500MPaである組成物）  [0068] (Composition having a shear storage modulus at 23 ° C of 1 to 500 MPa)
本発明の輝度向上フィルムに用 ヽる接着層を構成する組成物は、温度 23°Cにお ける剪断貯蔵弾性率が l〜500MPaである。  The composition constituting the adhesive layer used in the brightness enhancement film of the present invention has a shear storage modulus at a temperature of 23 ° C. of 1 to 500 MPa.
[0069] 前記組成物は、少なくとも接着剤を構成する主ポリマーを含有する。該主ポリマーと しては、アクリル系重合体およびアクリル系共重合体、シリコーン系ポリマー、ポリエス テル、ポリウレタン、ポリアミド、ポリビュルエーテル、ポリビュルアルコール、エチレン z酢酸ビニル共重合体、エチレン Zアクリル酸エステル共重合体、エチレン Z塩ィ匕 ビュル共重合体、熱可塑性エラストマ一、エポキシ系、天然ゴム系、合成ゴム系など が挙げられる。これらの中でも、透明性に優れ、適度な濡れ性と凝集力を示し、耐候 性に優れる点で、熱可塑性エラストマ一、エチレン Z酢酸ビュル共重合体、エチレン Zアクリル酸エステル共重合体が好ましい。熱可塑性エラストマ一とは、加硫処理を しなくても、室温でゴム弾性を有する榭脂であり、具体的には、スチレン ブタジエン ブロック共重合体、スチレン エチレンブロック共重合体、スチレン ブタジエンース チレンブロック共重合体、スチレン イソプレン スチレンブロック共重合体、スチレ ン一エチレンブチレン一スチレンブロック共重合体、スチレン一エチレンプロピレン一 スチレンブロック共重合体、エチレン プロピレン共重合体およびエチレン プロピ レンターポリマー、ポリエチレン、ポリプロピレンおよびこれらにカルボキシル基、スル ホニル基を導入したものが挙げられる。また、これらの主ポリマーの分子量は、ゲル' パーミエーシヨン ·クロマトグラフィーで測定したポリイソプレンの重量平均分子量（M w)で、通常 10, 000〜500, 000であり、好ましくは 20, 000〜400, 000である。 [0069] The composition contains at least a main polymer constituting an adhesive. Examples of the main polymer include acrylic polymers and acrylic copolymers, silicone polymers, polyesters, polyurethanes, polyamides, polybutyl ethers, polybulal alcohols, ethylene z vinyl acetate copolymers, ethylene Z acrylic acids. Ester copolymer, ethylene Z salt butyl copolymer, thermoplastic elastomer, epoxy, natural rubber, synthetic rubber, etc. Is mentioned. Among these, a thermoplastic elastomer, an ethylene Z-butyl acetate copolymer, and an ethylene Z acrylate copolymer are preferable because they are excellent in transparency, exhibit appropriate wettability and cohesion, and have excellent weather resistance. Thermoplastic elastomer is a resin having rubber elasticity at room temperature without vulcanization treatment. Specifically, styrene butadiene block copolymer, styrene ethylene block copolymer, styrene butadiene polystyrene block. Copolymer, styrene isoprene styrene block copolymer, styrene-ethylene butylene-styrene block copolymer, styrene-ethylene propylene-styrene block copolymer, ethylene propylene copolymer and ethylene propylene terpolymer, polyethylene, polypropylene and These may be those introduced with a carboxyl group or a sulfonyl group. The molecular weight of these main polymers is the weight average molecular weight (Mw) of polyisoprene measured by gel permeation chromatography, and is usually 10,000 to 500,000, preferably 20,000 to 400,000.
[0070] 前記組成物には、主ポリマーの種類に応じて、他の配合剤を配合することができる 。他の配合剤としては、粘着付与剤、架橋剤又は硬化剤、酸化防止剤、光拡散剤、 消泡剤、安定剤が挙げられる。  [0070] Depending on the type of the main polymer, other compounding agents can be blended in the composition. Examples of other compounding agents include tackifiers, crosslinking agents or curing agents, antioxidants, light diffusing agents, antifoaming agents, and stabilizers.
[0071] 上記粘着付与剤は、軟ら力べなりかつ固体表面が濡れやすくなつた主ポリマーに、 粘着力を付与するものである。このような粘着付与剤としては、ロジンおよびロジン誘 導体、ポリテルペン榭脂、テルペンフエノール榭脂、クマロン-インデン榭脂、石油榭 脂、水素化石油榭脂などが挙げられる。これらの中でも、透明性や主ポリマーとの相 溶性に優れる点で、石油榭脂、水素化石油榭脂、テルペンフエノール榭脂が好まし い。粘着付与剤の配合量は、主ポリマー 100重量部に対して、好ましくは 2〜50重量 部であり、より好ましくは 5〜20重量部である。粘着付与剤の添加量が 2重量部より少 ないと、粘着付与剤の効果が発現せず、逆に添加量が 50重量部を超えると、接着剤 の凝集力の低下による接着力の低下が見られる傾向がある。  [0071] The tackifier described above imparts adhesive force to a main polymer that is soft and strong, and whose solid surface is easily wetted. Such tackifiers include rosin and rosin derivatives, polyterpene resin, terpene phenol resin, coumarone-indene resin, petroleum resin, hydrogenated petroleum resin and the like. Of these, petroleum resin, hydrogenated petroleum resin, and terpene phenol resin are preferred because of their excellent transparency and compatibility with the main polymer. The compounding amount of the tackifier is preferably 2 to 50 parts by weight, more preferably 5 to 20 parts by weight with respect to 100 parts by weight of the main polymer. If the addition amount of the tackifier is less than 2 parts by weight, the effect of the tackifier will not be exhibited. There is a tendency to be seen.
[0072] 上記架橋剤又は硬化剤としては、トリレンジイソシァネート、へキサメチレンジイソシ ァネート、テトラメチレンジイソシァネート、トリメチロールプロパントリレンジイソシァネ ート、ジフエ-ルメタントリイソシァネートなどの多官能イソシァネート架橋剤又は硬化 剤；エチレングリコールグリシジルエーテル、ポリエチレングリコールジグリシジルエー テル、ジグリシジルエーテル、トリメチロールプロパントリグリシジルエーテル、などの エポキシ系架橋剤又は硬化剤；ビュルトリメトキシシラン、メタクリロキシプロピルトリメト キシシラン、 3 グリシドキシプロピノレトリメトキシシラン， 2- (3, 4 エポキシシクロへ キシル)ェチルトリメトキシシラン、 3 ァミノプロピルトリメトキシシラン， N— (2 ァミノ ェチル） 3—ァミノプロピルトリメトキシシランなどのシラン系架橋剤又は硬化剤;メラミ ン榭脂系架橋剤;金属キレート系架橋剤;アミン系架橋剤が用いられる。架橋剤又は 硬化剤の配合量は、主ポリマー 100重量部に対して、好ましくは 0. 001〜10重量部 であり、より好ましくは 0. 01〜3重量部である。架橋剤又は硬化剤の添加量が 0. 00 1重量部より少ないと、架橋剤の効果が発現せず、耐候性試験などで発泡や剥離が 目立つ。逆に架橋剤又は硬化剤の添加量が 10重量部より多くなると、接着剤の応力 緩和性が低下し、ソリなどが目立つようになる。 [0072] Examples of the crosslinking agent or curing agent include tolylene diisocyanate, hexamethylene diisocyanate, tetramethylene diisocyanate, trimethylolpropane tolylene diisocyanate, diphenylmethane triisocyanate. Polyfunctional isocyanate crosslinking agents such as sulfonates or curing agents; ethylene glycol glycidyl ether, polyethylene glycol diglycidyl ether Epoxy crosslinking agents or curing agents such as ter, diglycidyl ether, trimethylolpropane triglycidyl ether; butyltrimethoxysilane, methacryloxypropyltrimethoxysilane, 3 glycidoxypropinoretrimethoxysilane, 2- (3, 4 Epoxycyclohexyl) ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, N- (2aminoethyl) 3-aminopropyltrimethoxysilane, and other silane-based crosslinking agents or curing agents; melamine resin A crosslinking agent; a metal chelate crosslinking agent; an amine crosslinking agent is used. The amount of the crosslinking agent or curing agent is preferably 0.001 to 10 parts by weight, more preferably 0.01 to 3 parts by weight with respect to 100 parts by weight of the main polymer. When the addition amount of the crosslinking agent or curing agent is less than 0.001 part by weight, the effect of the crosslinking agent is not exhibited, and foaming and peeling are conspicuous in a weather resistance test. On the other hand, when the addition amount of the crosslinking agent or curing agent is more than 10 parts by weight, the stress relaxation property of the adhesive is lowered, and warpage becomes conspicuous.
[0073] 上記酸ィ匕防止剤としては、テトラキス (メチレン 3—（3, 5ジー t—プチルー 4ーヒド ロキシフエ-ル)プロピオネート)メタン等のフエノール系酸ィ匕防止剤、リン系酸化防止 剤、チォエーテル系酸化防止剤が挙げられる。酸化防止剤の配合量は、接着層の 透明性や接着力が低下しない範囲である。  [0073] Examples of the above-mentioned anti-oxidation agent include tetrakis (methylene 3- (3,5-di-tert-butyl 4-hydroxyphenyl) propionate) phenol-based anti-oxidation agents such as methane, phosphorus-based antioxidants, Examples include thioether-based antioxidants. The blending amount of the antioxidant is within a range where the transparency and adhesive strength of the adhesive layer are not lowered.
[0074] 本発明に用いる接着層を構成する組成物の剪断貯蔵弾性率は、主ポリマー糸且成 および粘着付与剤の添加量、架橋剤の添加量などにより変化する。  [0074] The shear storage modulus of the composition constituting the adhesive layer used in the present invention varies depending on the main polymer yarn and the addition amount of the tackifier, the addition amount of the crosslinking agent, and the like.
主ポリマー組成については、共重合体において、ソフトセグメントとなるモノマーの 比率を上げることにより、常温における剪断貯蔵弾性率が低下する傾向がある。逆に ハードセグメントとなるモノマーの比率を上げることにより、常温における剪断貯蔵弹 性率は上昇する傾向がある。また、同組成物においても、重合体の分子量を低下さ せることでゴム状平坦領域を示す温度幅が狭くなり、常温における剪断貯蔵弾性率 が低下する傾向にある。逆に、重合体の分子量を上昇させることでゴム状平坦領域 を示す温度幅が広くなり、常温における剪断貯蔵弾性率が上昇する傾向にある。粘 着付与剤は一般に、軟化点が 60度以上と高ぐ分子量が数千程度と低い。粘着付 与剤を添加することで、接着剤組成物の凝集力が低下し、室温における剪断貯蔵弾 性率の低下が見られる。また、架橋剤を混合することで、接着剤組成物の凝集力が 上昇し、室温における剪断貯蔵弾性率の上昇が見られる。 [0075] 前記組成物、すなわち、ホットメルト型接着剤の 23°Cにおける剪断貯蔵弾性率は、 l〜500MPaに調製することが必須要件である。 23°Cにおける剪断貯蔵弾性率が 1 MPa未満であると、常温において粘着性が発現し、積層フィルムの打ち抜きなどの 後加工の際に、打ち抜き刃やタブ剤に糊残りが生じてしまう。逆に、 23°Cにおける剪 断貯蔵弾性率が 500MPaを超えると、フィルムをラミネートするために必要な粘着性 を発現させるために、例えば 110°Cを超えるような高温になるまで加熱しなければな らない。 110°Cを超える温度では、フィルムへの熱負荷が大き過ぎて、フィルムに変 形が生じるおそれがある。また、接着剤のフィルムとの接着力も低下する。前記組成 物の 23°Cにおける剪断貯蔵弾性率は、好ましくは 2〜300MPaであり、より好ましく は 5〜250MPaである。 Regarding the main polymer composition, the shear storage modulus at room temperature tends to decrease by increasing the ratio of the monomer that becomes the soft segment in the copolymer. Conversely, increasing the ratio of monomers that become hard segments tends to increase the shear storage durability at room temperature. Also in the same composition, by reducing the molecular weight of the polymer, the temperature range showing the rubber-like flat region is narrowed, and the shear storage modulus at room temperature tends to decrease. On the other hand, increasing the molecular weight of the polymer tends to increase the temperature range showing the rubbery flat region and increase the shear storage modulus at room temperature. Tackifiers generally have a high softening point of 60 degrees or higher and a low molecular weight of about several thousand. By adding a tackifier, the cohesive strength of the adhesive composition is lowered, and a decrease in shear storage elasticity at room temperature is observed. In addition, the cohesive strength of the adhesive composition is increased by mixing the cross-linking agent, and an increase in the shear storage modulus at room temperature is observed. [0075] The shear storage elastic modulus at 23 ° C of the composition, that is, the hot-melt adhesive, must be adjusted to 1 to 500 MPa. If the shear storage modulus at 23 ° C is less than 1 MPa, adhesiveness will develop at room temperature, and adhesive residue will occur on the punching blade and tab agent during post-processing such as punching of laminated film. Conversely, if the shear storage modulus at 23 ° C exceeds 500MPa, it must be heated to a high temperature, for example, over 110 ° C, in order to develop the adhesiveness required to laminate the film. It must be. At temperatures above 110 ° C, the heat load on the film is too great and the film may be deformed. Moreover, the adhesive force with the film of an adhesive agent also falls. The shear storage modulus at 23 ° C. of the composition is preferably 2 to 300 MPa, more preferably 5 to 250 MPa.
[0076] 前記接着剤により積層してなる輝度向上フィルムの 180度剥離接着強度は、 ION Z25mm以上とすることができる。また、積層された輝度向上フィルムにおける接着 層の全光線透過率は、 80%以上、さらには 85%以上に設定可能であり、位相差フィ ルムカ Sスチレン系榭脂層を有するために高 、透明性を有することと合わせて、本発 明の輝度向上フィルムの透明性は、従来品を凌駕する透明性を具備することができ る。  [0076] The 180 degree peel adhesive strength of the brightness enhancement film laminated with the adhesive may be ION Z 25 mm or more. In addition, the total light transmittance of the adhesive layer in the laminated brightness enhancement film can be set to 80% or more, and more than 85%, and because it has a retardation film S styrene resin layer, it is highly transparent. In addition, the transparency of the brightness enhancement film of the present invention can be higher than that of conventional products.
[0077] 前記組成物を用いて接着剤として使用する場合は、前記組成物を溶剤又は水に、 溶解又は分散させて用いる。前記溶剤としては、トルエン、酢酸ェチル、酢酸ブチル 、酢酸イソブチル、メチルェチルケトン、メチルイソブチルケトン、メタノール、エタノー ル、イソプロピルアルコール、 n—プロピルアルコール、 n—ブチルアルコール、イソブ チルアルコールなどを用いることができる。  [0077] When the composition is used as an adhesive, the composition is dissolved or dispersed in a solvent or water. As the solvent, toluene, ethyl acetate, butyl acetate, isobutyl acetate, methyl ethyl ketone, methyl isobutyl ketone, methanol, ethanol, isopropyl alcohol, n-propyl alcohol, n-butyl alcohol, isobutyl alcohol, etc. should be used. Can do.
[0078] 本発明の輝度向上フィルムにおいて、接着層の平均厚みが、 2 μ m〜50 μ mであ ることが好ましぐ 5 μ m〜30 μ mであることがより好ましい。平均厚みは、接着層の 厚みを幅方向に等間隔に測定し、各測定点における測定値の平均値で表される。  In the brightness enhancement film of the present invention, the average thickness of the adhesive layer is preferably 2 μm to 50 μm, more preferably 5 μm to 30 μm. The average thickness is represented by the average value of the measured values at each measurement point when the thickness of the adhesive layer is measured at equal intervals in the width direction.
[0079] (輝度向上フィルムの製造方法）  [0079] (Method for producing brightness enhancement film)
本発明の輝度向上フィルムの製造方法は、前記偏光分離フィルムと前記位相差フ イルムとを、前記接着層を介して貼り合わせる工程を含み、前記貼り合わせる工程に ぉ 、て前記偏光分離フィルムおよび前記位相差フィルムを 40°C〜 110°Cの範囲で 加熱して貼り合わせることを特徴とする。 The method for producing a brightness enhancement film of the present invention includes a step of bonding the polarization separation film and the retardation film through the adhesive layer. The bonding step includes the steps of bonding the polarization separation film and the Retardation film in the range of 40 ° C to 110 ° C It is characterized by being bonded by heating.
[0080] 接着層を形成する方法としては、接着層を構成する組成物を、偏光分離フィルム又 は位相差フィルムに直接、塗工し、乾燥する方法;ポリエチレンテレフタレートフィルム や表面にシリコーン系もしくはフッ素系離型処理を施したポリエチレンテレフタレート フィルムの表面に、接着層を構成する組成物を塗工、乾燥し、これを偏光分離フィル ム又は位相差フィルムに転写する方法が挙げられる。  [0080] As a method for forming the adhesive layer, the composition constituting the adhesive layer is directly applied to a polarized light separation film or retardation film and dried; a polyethylene terephthalate film or a silicone-based or fluorine-based film is used. Examples include a method of coating the composition constituting the adhesive layer on the surface of the polyethylene terephthalate film that has been subjected to the mold release treatment, drying the composition, and transferring the composition to a polarizing separation film or a retardation film.
[0081] 接着剤の塗工方法は特に制限されず、例えば、ロールコート法、グラビアコート法、 スピンコート法、バーコート法などが挙げられる。また、偏光分離フィルム又は位相差 フィルムに接着層を構成する組成物を直接塗工する場合には、濡れ性および密着性 を高めるために、塗工面を、適宜プラズマ放電処理、コロナ放電処理、紫外線処理、 又は火炎処理してもよい。  [0081] The method of applying the adhesive is not particularly limited, and examples thereof include a roll coating method, a gravure coating method, a spin coating method, and a bar coating method. In addition, when the composition constituting the adhesive layer is directly applied to the polarization separation film or the retardation film, the coating surface is appropriately subjected to plasma discharge treatment, corona discharge treatment, ultraviolet ray in order to improve wettability and adhesion. It may be treated or flame treated.
[0082] 本発明にお ヽて、接着層を構成する組成物を、偏光分離フィルムに形成させる場 合には、液晶表示装置に搭載した時の輝度向上率および外観を鑑みて形成させる ことが好ましい。ここで輝度向上率とは、液晶表示装置に本発明における輝度向上フ イルムを搭載した時の輝度値と搭載して ヽな 、時の輝度値の比で表される値である。  In the present invention, when the composition constituting the adhesive layer is formed on the polarization separation film, it may be formed in view of the luminance improvement rate and the appearance when mounted on a liquid crystal display device. preferable. Here, the luminance improvement rate is a value represented by a ratio between the luminance value when the luminance enhancement film according to the present invention is installed in the liquid crystal display device and the luminance value when it is installed.
[0083] 次いで、接着層と、接着層が形成されていない偏光分離フィルム又は位相差フィル ムとを、 40°C〜110°Cの範囲で加熱して貼り合わせる。偏光分離フィルムまたは位相 差フィルムの貼り合わせ面は、接着性を高めるために、プラズマ放電処理、コロナ放 電処理、紫外線処理、火炎処理を施されていることが好ましい。貼り合わせ温度が、 40°C未満であると偏光分離フィルムと位相差フィルムの接着が不十分となり、逆に 1 10°Cを超えるとフィルムの変形、ソリなどが発生しやすくなる。貼り合わせ温度の好ま しい範囲は、 60°C〜100°Cである。  [0083] Next, the adhesive layer and the polarization separation film or retardation film on which the adhesive layer is not formed are bonded together by heating in the range of 40 ° C to 110 ° C. The bonded surface of the polarization separation film or retardation film is preferably subjected to plasma discharge treatment, corona discharge treatment, ultraviolet treatment, and flame treatment in order to enhance adhesion. If the laminating temperature is less than 40 ° C, adhesion between the polarization separation film and the retardation film becomes insufficient. Conversely, if it exceeds 110 ° C, deformation or warping of the film tends to occur. A preferable range of the bonding temperature is 60 ° C to 100 ° C.
[0084] (液晶表示装置を構成する部材）  (Member constituting liquid crystal display device)
本発明では、前記偏光分離フィルム 1を後述の特定の接着層を介して 1Z4波長板 と組み合わせて輝度向上フィルムを構成し、この輝度向上フィルムを、偏光子 X、液 晶セル、及び偏光子 Yを少なくとも有する液晶表示装置に取り付け、偏光子 X、液晶 セル、偏光子 Y、本発明の輝度向上フィルム (位相差フィルム +接着層 +偏光分離 フィルム）の順に配列することによって、輝度を向上させた液晶表示装置を得ることが できる。 In the present invention, the polarization separation film 1 is combined with a 1Z4 wavelength plate through a specific adhesive layer described later to form a brightness enhancement film, and the brightness enhancement film is composed of the polarizer X, the liquid crystal cell, and the polarizer Y. The brightness was improved by arranging the polarizer X, the liquid crystal cell, the polarizer Y, and the brightness enhancement film of the present invention (retardation film + adhesive layer + polarization separation film) in this order. To get a liquid crystal display it can.
[0085] 本発明に用いる偏光子 X及び Yは、液晶表示装置等に用いられている公知の偏光 子である。本発明に用いる偏光子は直角に交わる二つの直線偏光の一方を透過す るものである。例えば、ポリビュルアルコールフィルムやエチレン酢酸ビュル部分ケン 化フィルム等の親水性高分子フィルムにヨウ素や二色性染料などの二色性物質を吸 着させて一軸延伸させたもの、前記親水性高分子フィルムを一軸延伸して二色性物 質を吸着させたもの、ポリビニルアルコールの脱水処理物やポリ塩化ビニルの脱塩 酸処理物等のポリェン配向フィルムなどが挙げられる。その他に、グリッド偏光子、多 層偏光子などの偏光を反射光と透過光に分離する機能を有する偏光子が挙げられ る。これらのうちポリビュルアルコールを含有する偏光子が好まし!/、。  [0085] Polarizers X and Y used in the present invention are known polarizers used in liquid crystal display devices and the like. The polarizer used in the present invention transmits one of two linearly polarized light intersecting at right angles. For example, a hydrophilic polymer film such as a polybulualcohol film or ethylene acetate bull partially saponified film adsorbed with a dichroic substance such as iodine or a dichroic dye and uniaxially stretched, or the hydrophilic polymer film Examples thereof include a film obtained by uniaxially stretching a film to adsorb a dichroic material, and a polyethylene oriented film such as a dehydrated polyvinyl alcohol product or a dechlorinated polyvinyl chloride treated product. In addition, a polarizer having a function of separating polarized light into reflected light and transmitted light, such as a grid polarizer and a multilayer polarizer. Of these, polarizers containing polybulal alcohol are preferred!
[0086] 本発明に用いる偏光子の偏光度は、特に限定されないが、好ましくは 98%以上、 より好ましくは 99%以上である。偏光子の平均厚みは好ましくは 5〜80 μ mである。 偏光子 Xの偏光透過軸と偏光子 Yの偏光透過軸とは、直角になるように、液晶セル を挟むように配置する。偏光子は吸湿によって偏光性能が変化することがある。これ を防ぐために保護フィルムが偏光子 Xまたは Yの両面に通常貼り合わせてある。  The polarization degree of the polarizer used in the present invention is not particularly limited, but is preferably 98% or more, more preferably 99% or more. The average thickness of the polarizer is preferably 5 to 80 μm. The polarization transmission axis of the polarizer X and the polarization transmission axis of the polarizer Y are arranged so as to be perpendicular to each other with the liquid crystal cell sandwiched therebetween. Polarizer performance may change due to moisture absorption. To prevent this, protective films are usually attached to both sides of the polarizer X or Y.
[0087] 液晶セルは、数 μ mのギャップを隔てて対向する透明電極を設けた 2枚のガラス基 板の間に液晶物質を充填し、この電極に電圧を掛けて液晶の配向状態を変化させ てここを通過する光の量を制御するものである。  In a liquid crystal cell, a liquid crystal material is filled between two glass substrates provided with transparent electrodes facing each other with a gap of several μm, and a voltage is applied to the electrodes to change the alignment state of the liquid crystals. It controls the amount of light passing through here.
[0088] 液晶物質の配向状態を変化させる方式 (動作モード)などによって、液晶セルは分 類され、例えば、 TN (Twisted Nematic)型液晶セル、 STN (Super Twisted Nematic)型液晶セル、 HAN (Hybrid Alignment Nematic)型液晶セル、 IPS (In Plane Switching)型液晶セノレ、 VA (Vertical Alignment)型液晶セノレ、 M VA (Multiple Vertical Alignment型液晶セノレ、 OCB (Optical Compensate d Bend)型液晶セルなどが挙げられる。  [0088] The liquid crystal cell is classified according to a method (operation mode) for changing the alignment state of the liquid crystal substance. For example, a TN (Twisted Nematic) type liquid crystal cell, an STN (Super Twisted Nematic) type liquid crystal cell, and a HAN (Hybrid) Alignment Nematic) type liquid crystal cell, IPS (In Plane Switching) type liquid crystal senore, VA (Vertical Alignment) type liquid crystal senore, MVA (Multiple Vertical Alignment type liquid crystal senore), OCB (Optical Compensate d Bend) type liquid crystal cell .
[0089] (液晶表示装置）  [0089] (Liquid crystal display device)
図 2は、本発明の液晶表示装置の一例を示す図である。図 2に示すように、反射板 10、冷陰極管 11、拡散板 12、プリズムシート（図示せず)、偏光分離フィルム 1と位相 差フィルム 13とが接着剤層 14を介して積層されてなる輝度向上フィルム 15、偏光子 Y16、液晶セル 17、偏光子 X18の順に配置されている。光源力もの光には右偏光と 左偏光とが含まれている。その光が偏光分離フィルム 1に入射すると、一方の回転方 向の円偏光（図中光の進行方向に向って右回転の円偏光）はそのままの回転方向を 維持したまま偏光分離フィルム 1を透過する。他方の回転方向の円偏光（図中、光の 進行方向に向って左回転の円偏光）は偏光分離フィルム 1で反射される (反射された 円偏光は光の進行方向に向って左回転のままである)。透過した円偏光は、接着層 1 4を介して偏光分離フィルム 1に固着した位相差フィルム 13により偏光子 Y16の透過 軸と平行な直線偏光に変換される。一方、反射された円偏光は、拡散板 12で無偏光 となり、光源 11の背後に配置された反射板 10によって反射され、再び偏光分離フィ ルム 1に入射する。このようにして、光源 11から出射した光が有効利用され、画面の 表示輝度を向上させることができる。 FIG. 2 is a diagram showing an example of the liquid crystal display device of the present invention. As shown in FIG. 2, a reflector 10, a cold cathode tube 11, a diffuser 12, a prism sheet (not shown), a polarization separation film 1 and a retardation film 13 are laminated via an adhesive layer 14. Brightness enhancement film 15, polarizer Y16, liquid crystal cell 17, and polarizer X18 are arranged in this order. Light with a light source includes right and left polarized light. When the light enters the polarization separation film 1, the circularly polarized light in one rotation direction (circularly polarized light in the right direction toward the traveling direction of light in the figure) passes through the polarization separation film 1 while maintaining the same rotation direction. To do. The other circularly polarized light in the rotation direction (in the figure, circularly polarized light counterclockwise toward the light traveling direction) is reflected by the polarization separation film 1 (the reflected circularly polarized light is rotated counterclockwise toward the light traveling direction). Remain). The transmitted circularly polarized light is converted into linearly polarized light parallel to the transmission axis of the polarizer Y16 by the retardation film 13 fixed to the polarization separation film 1 through the adhesive layer 14. On the other hand, the reflected circularly polarized light becomes non-polarized light by the diffuser plate 12, is reflected by the reflector plate 10 disposed behind the light source 11, and is incident on the polarization separation film 1 again. In this way, the light emitted from the light source 11 is effectively used, and the display brightness of the screen can be improved.
[0090] なお、前記拡散板 12は、一般に、粒子状の拡散材が榭脂等のマトリックス中に均一 に分散し、それによつて光を散乱拡散する機能を有する板として知られて 、るもので ある。前記プリズムシートは、一般に、散乱等により広く進行方向が広がった光をシー ト面法線方向に狭める機能を有するシートとして知られて ヽるものである。  [0090] Note that the diffusion plate 12 is generally known as a plate having a function in which a particulate diffusion material is uniformly dispersed in a matrix such as a resin, thereby scattering and diffusing light. It is. The prism sheet is generally known as a sheet having a function of narrowing light having a wide traveling direction due to scattering or the like in the normal direction of the sheet surface.
[0091] また、図 2において、偏光分離フィルム 1と接着層 14との間、あるいは接着層 14と位 相差フィルム 13との間に拡散シートを介在させて固着させてもよい。拡散シートは、 一般に、透明フィルムの上に粒子状の拡散材が均一に分散するように積層されたも のであり、光を散乱拡散する機能を有するシートとして知られているものである。  In FIG. 2, a diffusion sheet may be interposed and fixed between the polarization separation film 1 and the adhesive layer 14 or between the adhesive layer 14 and the phase difference film 13. The diffusion sheet is generally a laminate on which a particulate diffusion material is uniformly dispersed on a transparent film, and is known as a sheet having a function of scattering and diffusing light.
[0092] 本発明では、偏光分離フィルム 1の、位相差フィルム 14側の面に、光拡散性を備え ていることが好ましい。光拡散性とは、光を散乱拡散する性質のことである。光拡散性 を備えさせるために、例えば、偏光分離フィルム 1の表面に、粒子状の拡散材を均一 に分散するように積層させる方法、基材に粒子状の拡散材を均一に分散する方法、 または前記拡散シート 12を偏光分離フィルム 1に貼りあわせる方法などが挙げられる 実施例  In the present invention, it is preferable that the surface of the polarization separation film 1 on the phase difference film 14 side has light diffusibility. The light diffusibility is a property of scattering and diffusing light. In order to provide light diffusibility, for example, a method of laminating a particulate diffusing material uniformly on the surface of the polarization separation film 1, a method of uniformly dispersing a particulate diffusing material on a substrate, Or a method of bonding the diffusion sheet 12 to the polarization separation film 1 etc.
[0093] 以下に、本発明の実施例を説明する。なお、以下の実施例により本発明はなんら 限定されるものではない。 [0094] 以下に、実施例 1〜4と、比較例 1〜3を示す。これらにおいては、輝度向上フィルム を構成する位相差フィルムと偏光分離フィルムとは同一構成のものを使用し、接着剤 層の構成のみを変更した。 [0093] Examples of the present invention will be described below. The present invention is not limited to the following examples. [0094] Examples 1 to 4 and Comparative Examples 1 to 3 are shown below. In these, the retardation film and the polarization separation film constituting the brightness enhancement film were the same, and only the configuration of the adhesive layer was changed.
[0095] (偏光分離フィルムの作成）  [0095] (Preparation of polarized light separation film)
平均厚み 100 m、幅 50mm、長さ 200mmの脂環式ォレフインポリマーからなるフ イルム（(株)ォプテス製、商品名「ゼォノアフィルム」）（以下、「基材」と記す。）の片面 を、濡れ指数が 56dyneZcmになるようにコロナ放電処理を施した。  One side of a film consisting of an alicyclic olefin polymer with an average thickness of 100 m, width of 50 mm, and length of 200 mm (trade name “Zeonor Film” manufactured by Optes Co., Ltd.) (hereinafter referred to as “base material”). The corona discharge treatment was applied so that the wetting index was 56 dyneZcm.
[0096] 次に、ポバール（(株)クラレネ土製、製品名「PVA226」）と、塩基としてトリヒドロキシ シリル基含有アミノ化合物とを混合比 80Z20 (重量比）で混合したものを、水 Zエタ ノール混合溶媒 (混合比 60Z40重量比）に固形分率が 3重量％となるように溶解し、 調整した。調整した溶液を、前記基材のコロナ放電処理を施した面に、ワイヤーバー # 2を用いて塗布し、 100°Cにて 5分間加熱、乾燥した。加熱乾燥して得た膜上に基 材の長手方向と平行にラビング処理を施し、厚さ 0. 1 μ mの配向膜を形成した。  [0096] Next, a mixture of POVAL (product name "PVA226" manufactured by KURARENE CO., LTD.) And a trihydroxysilyl group-containing amino compound as a base at a mixing ratio of 80Z20 (weight ratio) was added to water Z ethanol. It was dissolved and adjusted in a mixed solvent (mixing ratio 60Z40 weight ratio) so that the solid content was 3% by weight. The prepared solution was applied to the surface of the substrate subjected to corona discharge treatment using wire bar # 2, heated at 100 ° C. for 5 minutes, and dried. The film obtained by heating and drying was rubbed in parallel with the longitudinal direction of the base material to form an alignment film having a thickness of 0.1 μm.
[0097] 前記配向膜上に、下記表 1に示す組成の塗布液をワイヤバー # 6を用いて塗布し、 100°Cにて 5分間加熱、乾燥、および配向熟成した。熟成後の塗布膜に紫外線を 70 mjZcm2 (UV— A)を照射し、 100°Cにて 5分間保持し、次いで紫外線を照射して塗 布膜を硬化させ、平均膜厚 3 mのコレステリック榭脂層を形成し、偏光分離フィルム を得た。 [0097] On the alignment film, a coating solution having the composition shown in Table 1 below was applied using a wire bar # 6, heated at 100 ° C for 5 minutes, dried, and alignment-aged. The coated film after aging is irradiated with UV light of 70 mjZcm 2 (UV-A), held at 100 ° C for 5 minutes, and then irradiated with UV light to cure the coating film, resulting in an average film thickness of 3 m. A resin layer was formed to obtain a polarized light separation film.
得られたコレステリック榭脂層は、 400nm〜750nmまでの光線透過率が 55%であ り、反射率が 35%であった。  The obtained cholesteric resin layer had a light transmittance from 400 nm to 750 nm of 55% and a reflectance of 35%.
[0098] [表 1] [0098] [Table 1]
(表 1 ) (table 1 )
Figure imgf000025_0001
Figure imgf000025_0001
[0099] (位相差フィルムの作成） [0099] (Creation of retardation film)
メタクリル酸メチル 97. 8重量％とアクリル酸メチル 2. 2重量％とからなるモノマー組 成物を、バルタ重合法により重合させ、榭脂ペレットを得た。  A monomer composition composed of 97.8% by weight of methyl methacrylate and 2.2% by weight of methyl acrylate was polymerized by the Balta polymerization method to obtain a resin pellet.
[0100] 特公昭 55— 27576号公報の実施例 3に準じて、ゴム粒子を製造した。このゴム粒 子は、球形 3層構造を有し、芯内層が、メタクリル酸メチル及び少量のメタクリル酸ァリ ルの架橋重合体であり、内層が、主成分としてのアクリル酸ブチルとスチレン及び少 量のアクリル酸ァリルとを架橋共重合させた軟質の弾性共重合体であり、外層が、メ タクリル酸メチル及び少量のアクリル酸ェチルの硬質重合体である。また、内層の平 均粒子径は 0. 19 mであり、外層をも含めた粒径は 0. 22 mであった。  [0100] Rubber particles were produced according to Example 3 of JP-B-55-27576. This rubber particle has a spherical three-layer structure, the core inner layer is a crosslinked polymer of methyl methacrylate and a small amount of methacrylate, and the inner layer is composed of butyl acrylate and styrene as main components and a small amount. It is a soft elastic copolymer obtained by crosslinking copolymerization with an amount of allylic acrylate, and the outer layer is a hard polymer of methyl methacrylate and a small amount of ethyl acrylate. The average particle size of the inner layer was 0.19 m, and the particle size including the outer layer was 0.22 m.
[0101] 上記榭脂ペレット 70重量部と、上記ゴム粒子 30重量部とを混合し、二軸押出機で 溶融混練して、メタクリル酸エステル重合体組成物 A (ガラス転移温度 105°C)を得た  [0101] 70 parts by weight of the above resin pellets and 30 parts by weight of the above rubber particles were mixed and melt-kneaded by a twin screw extruder to obtain a methacrylic acid ester polymer composition A (glass transition temperature 105 ° C). Obtained
[0102] 上記メタクリル酸エステル重合体組成物 A (b層）、及びスチレン無水マレイン酸共 重合体 (ガラス転移温度 130°C) (a層）を温度 280°Cで共押出成形することにより、 b 層 Za層 Zb層の三層構造で、各層が 45Z70Z45 ( μ m)の平均厚みを有する複層 フィルムを得た。この複層フィルムを、延伸温度 128°C、延伸倍率 1. 4倍、延伸速度 10mZ分でテンタ一一軸延伸し、延伸複層フィルム (位相差フィルム）を得た。さらに この位相差フィルムの片面を、濡れ指数が 56dyneZcmになるようにコロナ放電処理 を施した。 [0102] The methacrylic acid ester polymer composition A (layer b) and the styrene maleic anhydride copolymer (glass transition temperature 130 ° C) (layer a) were coextruded at a temperature of 280 ° C. b layer Za layer A multilayer film having a three-layer structure of Zb layers, each layer having an average thickness of 45Z70Z45 (μm) was obtained. This multilayer film was stretched uniaxially with a tenter at a stretching temperature of 128 ° C., a stretching ratio of 1.4 times, and a stretching speed of 10 mZ to obtain a stretched multilayer film (retardation film). Furthermore, one side of this retardation film was subjected to corona discharge treatment so that the wetting index was 56 dyneZcm.
[0103] 得られた位相差フィルムの波長 550nmにおけるレターデーシヨン値は、厚み方向 のレターデーシヨン Rthは 118nm、面内方向のレターデーシヨン Reは 140nmで めつに。 [0103] The retardation value of the obtained retardation film at a wavelength of 550 nm is the thickness direction. Letter decision Rth is 118nm, and in-plane letter decision Re is 140nm.
[0104] (接着剤を構成する組成物の 23°Cにおける剪断貯蔵弾性率の測定方法）  [0104] (Method of measuring shear storage modulus of composition constituting adhesive at 23 ° C)
各接着剤液を計量カップにとり、 80°Cで 10時間、 100°Cで 30分乾燥機に入れて、 水分を除去し、厚み約 1. 5mmのサンプルを作製した。このサンプルを直径 8mmに カットし、粘弾性測定装置 (英弘精機製、 RheoStress RS600)を使用して温度 23 。C、周波数 1Ηζ、歪み量 0. 5%の条件にて測定した。  Each adhesive solution was placed in a measuring cup and placed in a dryer at 80 ° C for 10 hours and at 100 ° C for 30 minutes to remove moisture, and a sample having a thickness of about 1.5 mm was prepared. This sample was cut to a diameter of 8 mm and the temperature was 23 using a viscoelasticity measuring device (RheoStress RS600, manufactured by Eihiro Seiki). The measurement was performed under the conditions of C, frequency 1Ηζ, and strain amount 0.5%.
[0105] (実施例 1)  [0105] (Example 1)
エチレン 酢酸ビュル共重合体ェマルジヨン（不揮発分 40重量％、酢酸ビニル含 有率 40重量％) 40重量部、石油榭脂ェマルジヨン (不揮発分 40重量％、榭脂軟ィ匕 点 85°C)35重量部、及びパラフィンワックスェマルジヨン (不揮発分 40重量％、榭脂 軟化点 64°C) 10重量部力もなる、 23°Cにおける剪断貯蔵弾性率が lOMPaである 組成物にて形成される接着層を、前記偏光分離フィルムのコレステリック榭脂層上に 平均厚みが 20 mとなるように積層し、前記位相差フィルムのコロナ処理面とをラミネ 一ターを用いて、 80°C、 2kgfZ50mmの-ップ圧にて貼り合わせを行い、輝度向上 フイノレム 1を得た。  Ethylene acetate butyl copolymer emulsion (non-volatile content 40% by weight, vinyl acetate content 40% by weight) 40 parts by weight, petroleum oil emulsion (non-volatile content 40% by weight, resin softness point 85 ° C) 35% Part and paraffin wax emulsion (non-volatile content 40% by weight, resin softening point 64 ° C) Adhesive layer formed of a composition having a shear storage modulus of lOMPa at 23 ° C, which is 10 parts by weight Is laminated on the cholesteric resin layer of the polarized light separating film so that the average thickness is 20 m, and the corona-treated surface of the retardation film is laminated with a laminator at 80 ° C. and 2 kgfZ50 mm. Bonding was performed under pressure to obtain a brightness-enhanced FINEREM 1.
[0106] (実施例 2) [Example 2]
エチレン 酢酸ビュル共重合体ェマルジヨン（不揮発分 40重量％、酢酸ビニル含 有率 25重量％) 73重量部、石油榭脂ェマルジヨン (不揮発分 40重量％、榭脂軟ィ匕 点 85°C) 2重量部、及びパラフィンワックスェマルジヨン (不揮発分 40重量％、榭脂軟 化点 64°C) 10重量部力もなる、 23°Cにおける剪断貯蔵弾性率が lOOMPaである組 成物にて形成される接着層を、前記偏光分離フィルムのコレステリック樹脂層上に平 均厚みが 15 mとなるように積層し、前記位相差フィルムのコロナ処理面とをラミネ一 ターを用いて、 90°C、 2kgfZ50mmの-ップ圧にて貼り合わせを行い、輝度向上フ イルム 2を得た。  Ethylene acetate butyl copolymer emulsion (non-volatile content 40% by weight, vinyl acetate content 25% by weight) 73 parts by weight Petroleum resin emulsion (non-volatile content 40% by weight, soft oil soft point 85 ° C) 2% Part and paraffin wax emulsion (nonvolatile content 40% by weight, resin softening point 64 ° C) 10 parts by weight, formed of a composition having a shear storage modulus at 23 ° C of lOOMPa An adhesive layer is laminated on the cholesteric resin layer of the polarized light separating film so that the average thickness is 15 m, and the corona-treated surface of the retardation film is 90 ° C, 2 kgfZ50 mm, using a laminator. -Brightening film 2 was obtained by pasting together with the pressure.
[0107] (実施例 3) [Example 3]
スチレン アクリル酸エステル共重合体をベースポリマーとし、 23°Cにおける剪断 貯蔵弾性率が 50MPaである組成物（昭和高分子社製、ポリゾール L6850)からなる 接着層を、前記偏光分離フィルムのコレステリック樹脂層上に平均厚みが 18 mとな るように積層し、前記位相差フィルムのコロナ処理面とをラミネーターを用いて、 80°C 、 2kgfZ50mmの-ップ圧にて貼り合わせを行い、輝度向上フィルム 3を得た。 It is composed of a composition (made of Showa Polymer Co., Ltd., Polysol L6850) having a shear storage elastic modulus at 23 ° C of 50 MPa, based on a styrene acrylate copolymer. An adhesive layer is laminated on the cholesteric resin layer of the polarized light separating film so that the average thickness is 18 m, and the corona-treated surface of the retardation film is laminated with a laminator at 80 ° C. and 2 kgfZ50 mm. Bonding was performed under pressure to obtain a brightness enhancement film 3.
[0108] (実施例 4) [Example 4]
スチレン一ブタジエン一スチレン共重合体をベースポリマーとし、 23°Cにおける剪 断貯蔵弾性率が lOOMPaである組成物（旭化成ケミカルズ製 アサプレン T436)か らなる接着層を、前記偏光分離フィルムのコレステリック榭脂層上に平均厚みが 15 mとなるように積層し、前記位相差フィルムのコロナ処理面とをラミネーターを用いて、 90°C、 2kgfZ50mmの-ップ圧にて貼り合わせを行い、輝度向上フィルム 4を得た。  An adhesive layer made of a composition (asaprene T436, manufactured by Asahi Kasei Chemicals Co., Ltd.) having a pruned storage elastic modulus at 23 ° C of lOOMPa based on a styrene-butadiene-styrene copolymer as a base polymer is used as the cholesteric resin of the polarized light separating film. The film is laminated so that the average thickness is 15 m on the layer, and the corona-treated surface of the retardation film is laminated using a laminator at 90 ° C, 2 kgfZ50 mm -pump pressure, and the brightness enhancement film Got 4.
[0109] (比較例 1) [0109] (Comparative Example 1)
アクリル酸エステル共重合体をベースポリマーとし、 23°Cにおける剪断貯蔵弾性率 が 0. IMPaである組成物（大同化成工業製 E— 5301)からなる接着層を、前記偏 光分離フィルムのコレステリック樹脂層上に平均厚みが 25 mとなるように積層し、前 記位相差フィルムのコロナ処理面とをラミネーターを用いて、 25°C、 2kgfZ50mmの -ップ圧にて貼り合わせを行 、、輝度向上フィルム 5を得た。  An adhesive layer comprising a composition (E-5301, manufactured by Daido Kasei Kogyo Co., Ltd.) having a shear storage elastic modulus at 23 ° C of 0. IMPa as a base polymer is used as a cholesteric resin for the polarized light separation film. Laminate on the layer so that the average thickness is 25 m, and laminate the corona-treated surface of the above retardation film with a laminator at 25 ° C, 2 kgfZ50 mm -pump pressure, brightness Improved film 5 was obtained.
[0110] (比較例 2) [0110] (Comparative Example 2)
エチレン 酢酸ビュル共重合体ェマルジヨン（不揮発分 40重量％、酢酸ビニル含 有率 10重量％) 75重量部、パラフィンワックスェマルジヨン (不揮発分 40重量％、榭 脂軟ィ匕点 64°C) 10重量部力もなる、 23°Cにおける剪断貯蔵弾性率が lOOOMPaで ある組成物にて形成される接着層を、前記偏光分離フィルムのコレステリック榭脂層 上に平均厚みが 14 mとなるように積層し、前記位相差フィルムのコロナ処理面とを ラミネーターを用いて、 90°C、 2kgfZ50mmの-ップ圧にて貼り合わせを行い、輝度 向上フイノレム 6を得た。  Ethylene acetate butyl copolymer emulsion (non-volatile content 40% by weight, vinyl acetate content 10% by weight) 75 parts by weight, paraffin wax emulsion (non-volatile content 40% by weight, resin softness point 64 ° C) 10 An adhesive layer formed from a composition having a shear storage modulus at 23 ° C of lOOOMPa, which also has a weight force, is laminated on the cholesteric resin layer of the polarization separation film so as to have an average thickness of 14 m. Then, the corona-treated surface of the retardation film was bonded using a laminator at 90 ° C. and a 2 kgfZ50 mm negative pressure to obtain a brightness-enhancing Finolem 6.
[0111] (比較例 3) [0111] (Comparative Example 3)
アクリル酸エステル共重合体をベースポリマーとし、 23°Cにおける剪断貯蔵弾性率 力 ^OOMPaである組成物 (ニチゴーモビニール製 7980)力もなる接着層を、前記偏 光分離フィルムのコレステリック樹脂層上に平均厚みが 18 mとなるように積層し、前 記位相差フィルムのコロナ処理面とをラミネーターを用いて、 80°C、 2kgfZ50mmの -ップ圧にて貼り合わせを行 、、輝度向上フィルム 7を得た。 A composition having an acrylic ester copolymer as a base polymer and a shear storage modulus at 23 ° C of force ^ OOMPa (7980 made by Nichigomo Vinyl) has an adhesive layer on the cholesteric resin layer of the polarizing separation film. Laminate the corona-treated surface of the above retardation film with an average thickness of 18 m using a laminator. -Bonding was performed at a pressure, and a brightness enhancement film 7 was obtained.
[0112] (評価） [0112] (Evaluation)
( 1)接着性の評価：  (1) Evaluation of adhesiveness:
各例の輝度向上フィルムに対して 180度剥離試験 (剛性被着材として偏光分離フィ ルム、たわみ性被着材を位相差フィルムとした。）を、 JIS K6854— 2に準拠して実 施した。層間剥離せずに凝集破壊した場合を良好、層間剥離を起こした場合を不良 と判定した。その結果を下記表 2に示した。  A 180 degree peel test (polarized separation film as a rigid substrate and a phase difference film as a flexible substrate) was performed on the brightness enhancement film of each example in accordance with JIS K6854-2. . The case where cohesive failure occurred without delamination was judged good, and the case where delamination occurred was judged as poor. The results are shown in Table 2 below.
[0113] (2)打ち抜き加工時の打ち抜き刃への接着剤の付着度の評価： [0113] (2) Evaluation of the degree of adhesion of the adhesive to the punching blade during punching:
各例の輝度向上フィルムをトリミング用力ミソリ刃にて 50mm X 50mmサイズの矩形 に切り出し、その時の刃への接着剤の付着のありなしを目視にて観察した。その結果 を下記表 2に併記した。  The brightness enhancement film of each example was cut into a 50 mm X 50 mm size rectangle with a trimming force razor blade, and the presence or absence of adhesion of the adhesive to the blade at that time was visually observed. The results are also shown in Table 2 below.
[0114] [表 2] [0114] [Table 2]
(表 2 ) (Table 2)
Figure imgf000028_0001
Figure imgf000028_0001
[0115] 実施例の輝度向上フィルムでは接着層の 23°Cにおける剪断弾性率が 1〜 500MP aの範囲内に設定されており、接着性は良好であり、打ち抜き刃への接着剤付着もな かった。これに対して、接着剤の 23°Cにおける剪断弾性率が 0. IMPaであった比較 例 1では接着性が良好であつたが、打ち抜き刃に接着剤が付着した。接着剤の 23°C における剪断弾性率を 500MPaを超える値に設定した比較例 2 (lOOOMPa)と比較 例 3 (800MPa)では、打ち抜き刃への接着剤の付着はな力つたが、層間剥離を生じ 、接着性が不良であった。 [0115] In the brightness enhancement films of the examples, the shear elastic modulus at 23 ° C of the adhesive layer is set in the range of 1 to 500 MPa, the adhesiveness is good, and the adhesive does not adhere to the punching blade. won. On the other hand, in Comparative Example 1 in which the shear modulus of the adhesive at 23 ° C. was 0. IMPa, the adhesive property was good, but the adhesive adhered to the punching blade. In Comparative Example 2 (lOOOMPa) and Comparative Example 3 (800 MPa) where the shear modulus of the adhesive at 23 ° C was set to a value exceeding 500 MPa, the adhesive did not adhere to the punching blade, but delamination occurred. As a result, the adhesiveness was poor.
[0116] (実施例 5)  [0116] (Example 5)
反射板、冷陰極管、拡散板およびプリズムシートからなるバックライトユニット上に、 実施例 1で作製した輝度向上フィルム 1の偏光分離フィルム (A)側が拡散板側を向く ように配置し、ポリビュルアルコールにヨウ素を吸着させて得られた偏光子 Y、 ΤΝ型 液晶セル、偏光子 Υと同様の偏光子 Xとをこの順で配置し、図 2に示すような液晶表 示装置を作製した。 On the backlight unit consisting of a reflector, cold cathode tube, diffuser plate and prism sheet, Polarizer Y, Brightness-type liquid crystal cell, Polarized light obtained by placing the brightness-enhancing film 1 produced in Example 1 with the polarizing separation film (A) side facing the diffusion plate and adsorbing iodine to polybulal alcohol A polarizer X, similar to the child, was placed in this order to produce a liquid crystal display device as shown in Fig. 2.
[0117] この液晶表示装置を白表示モードにて発光させ、出光面側から観察した。表示面 は全面に亘って着色がなく、輝度向上フィルム端部には接着層の欠けに基づくムラ は視認されな力つた。  [0117] This liquid crystal display device was caused to emit light in the white display mode and observed from the light exit surface side. The display surface was not colored over the entire surface, and unevenness due to the lack of the adhesive layer was observed at the edge of the brightness enhancement film.
[0118] (比較例 4)  [0118] (Comparative Example 4)
輝度向上フィルムを比較例 1で作製したものに変更した以外は、実施例 5と同様に ノ ックライトユニット上に組み込み、液晶表示装置を作製した。  A liquid crystal display device was produced by incorporating it into the knocklight unit in the same manner as in Example 5 except that the brightness enhancement film was changed to that produced in Comparative Example 1.
[0119] この液晶表示装置を実施例 5と同様に白表示モードにて発光させ、出光面側から 観察した。表示面は全面に亘つて着色はないものの、輝度向上フィルム端部に接着 層の欠けに基づくムラが視認された。  This liquid crystal display device was caused to emit light in the white display mode in the same manner as in Example 5 and observed from the light exit surface side. Although the display surface was not colored over the entire surface, unevenness due to the chipping of the adhesive layer was observed at the edge of the brightness enhancement film.
[0120] 以上説明したように、本発明にかかる輝度向上フィルムは、透明性、打ち抜き加工 性が良好であり、し力も、製品コストの低減ィ匕が可能であり、液晶表示装置を始め各 種表示装置に使用することにより表示装置の輝度を向上するとともに、表示装置のコ ストを低減することができる。  [0120] As described above, the brightness enhancement film according to the present invention has good transparency and punching workability, and can reduce the product cost, and various types of liquid crystal display devices can be used. When used in a display device, the luminance of the display device can be improved and the cost of the display device can be reduced.

Claims

請求の範囲 The scope of the claims
[1] スチレン系榭脂層を含む榭脂フィルムを延伸してなる位相差フィルム、  [1] A retardation film obtained by stretching a resin film including a styrene-based resin layer,
コレステリック規則性を有する榭脂層を含む偏光分離フィルム、および  A polarized light separating film comprising a resin layer having cholesteric regularity, and
前記位相差フィルムと前記偏光分離フィルムとの間に、温度 23°Cにおける剪断貯 蔵弾性率が 1〜 500MPaである組成物カゝらなる接着層を含むことを特徴とする輝度 向上フイノレム。  A luminance-enhancing Finolem comprising an adhesive layer comprising a composition having a shear storage elastic modulus of 1 to 500 MPa at a temperature of 23 ° C. between the retardation film and the polarization separation film.
[2] 前記接着層が常温で粘着性を示さないことを特徴とする請求項 1に記載の輝度向 上フィルム。  [2] The brightness enhancement film according to [1], wherein the adhesive layer does not exhibit tackiness at room temperature.
[3] 前記接着層の平均厚みが 2 m〜50 mであることを特徴とする請求項 1に記載 の輝度向上フィルム。  [3] The brightness enhancement film according to claim 1, wherein an average thickness of the adhesive layer is 2 m to 50 m.
[4] 前記コレステリック規則性を有する榭脂層が、重合性液晶化合物を含む液晶組成 物を重合して形成された非液晶性の榭脂層であることを特徴とする請求項 1に記載 の輝度向上フィルム。  [4] The resin layer according to claim 1, wherein the resin layer having cholesteric regularity is a non-liquid crystalline resin layer formed by polymerizing a liquid crystal composition containing a polymerizable liquid crystal compound. Brightness enhancement film.
[5] 前記位相差フィルムの、式 I :Rth= { (nx+ny) Z2— nz} X d (式中、 nxは厚み方 向に垂直な方向であって最大の屈折率を与える方向の屈折率を表し、 nyは厚み方 向に垂直で nxの方向に直交する方向の屈折率であり、 nzは厚み方向の屈折率を表 し、 dは膜厚を表す。）で表される厚み方向のレターデーシヨン値 Rth力 20〜一 1 OOOnmであることを特徴とする請求項 1に記載の輝度向上フィルム。  [5] Formula I: Rth = {(nx + ny) Z2—nz} Xd (where nx is a direction perpendicular to the thickness direction and giving the maximum refractive index). Ny is the refractive index in the direction perpendicular to the nx direction and perpendicular to the nx direction, nz is the refractive index in the thickness direction, and d is the thickness. 2. The brightness enhancement film according to claim 1, wherein the direction letter value Rth force is 20 to 1 OOOnm.
[6] 請求項 1に記載の輝度向上フィルムの製造方法であって、  [6] The method for producing a brightness enhancement film according to claim 1,
前記偏光分離フィルムと前記位相差フィルムとを、前記接着層を介して貼り合せる 工程を含み、  Including the step of bonding the polarization separation film and the retardation film through the adhesive layer,
前記貼り合わせる工程にぉ 、て、前記偏光分離フィルムおよび前記位相差フィル ムを、 40°C〜110°Cの範囲で加熱して貼り合わせることを特徴とする輝度向上フィル ムの製造方法。  The method for producing a brightness enhancement film, wherein the polarizing separation film and the retardation film are bonded together by heating in the range of 40 ° C. to 110 ° C. in the step of bonding.
[7] 請求項 1に記載の輝度向上フィルムを有することを特徴とする液晶表示装置。  7. A liquid crystal display device comprising the brightness enhancement film according to claim 1.
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