JP2009210789A - Optical member and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical member reduced in the degree of development of difficulty in peeling due to change with time, and to provide a liquid crystal display device reduced in thickness while maintaining durability and easily recyclable. <P>SOLUTION: The optical member comprises a polarizing plate, a first adhesive layer, a retardation film, a second adhesive layer, and a circularly polarized light separation element, wherein (PX-P<SB>11</SB>)<(QX-Q<SB>11</SB>) is established with respect to: initial peeling force P<SB>11</SB>at 25°C of an interface between the polarizing plate and the first adhesive layer; peeling force Q<SB>11</SB>at 25°C after 150°C, 8 hr aging thereof; initial peeling force PX at 25°C from the retardation film to the circularly polarized light separation element; and peeling force QX at 25°C after 150°C, 8hr aging from the retardation film to the circularly polarized light separation element, and the first adhesive layer is formed of a cured product of a silicone-based composition. The liquid crystal display device includes this optical member. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an optical member and a liquid crystal display device.

  In a display device such as a liquid crystal display device, it is known to provide an optical element for improving luminance. For example, it has been proposed to provide a brightness enhancement film on the back side of the liquid crystal cell of the liquid crystal display device, that is, on the backlight side. The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis or circularly polarized light having a predetermined spiral axis direction and reflecting other light when light is incident from a light source such as a backlight of a liquid crystal display device or the like. Is.

  When light incident from a light source such as a backlight enters the brightness enhancement film, light in a predetermined polarization state among the light is transmitted. On the other hand, light other than the predetermined polarization state is reflected without being transmitted and returns to the backlight. The polarization state of the light returning to the backlight is changed by a reflector or the like provided there. When the light whose polarization state is inverted is incident again on the brightness enhancement film, the light in the predetermined polarization state among the light passes through the brightness enhancement film. By repeating this cycle, the amount of light transmitted through the brightness enhancement film and the amount of light that can be used for a liquid crystal display device by supplying polarized light that is not easily absorbed by the polarizing plate can be increased, thereby increasing the brightness of the liquid crystal display device. Can be improved.

  In a liquid crystal display device, it is known that such a brightness enhancement film is stuck on a polarizing plate of a liquid crystal panel and integrated from the viewpoint of thinning the device and preventing deformation of the film (Patent Document 1). ). For such sticking, acrylic adhesives and pressure-sensitive adhesives are widely used.

JP 2003-149634 A

  When the liquid crystal display device is used as a product and then discarded, useful resources are collected and recycled. However, in the case of a liquid crystal display device having a structure in which a brightness enhancement film is attached to a polarizing plate on a liquid crystal panel, there is a problem that it is difficult to peel off the brightness enhancement film during such recycling. Products with laminated materials on the film via an adhesive may have a stronger adhesion between layers due to the deterioration of the adhesive that accompanies use. In such cases, it is particularly difficult to peel off the brightness enhancement film. become.

  The present invention has been made in view of the above-described conventional problems, and an object of the present invention is to provide an optical member having a low degree of difficulty in peeling due to aging.

  A further object of the present invention is to provide a liquid crystal display device which can be thinned and has excellent durability and can be easily recycled.

  As a result of intensive studies to solve the above problems, the present inventors can solve the above problems by adopting a specific adhesive layer interposed between the polarizing plate, the retardation film and the circularly polarized light separating element. As a result, the present invention has been completed.

That is, according to the present invention, the following [1] to [6] are provided:
[1] In an optical member having a polarizing plate, a first adhesive layer, a retardation film, a second adhesive layer, and a circularly polarized light separating element, initial peeling at 25 ° C. at the interface between the polarizing plate and the first adhesive layer Force P ₁₁ and peeling force Q ₁₁ at 25 ° C. after aging for 8 hours at 150 ° C., initial peeling force PX at 25 ° C. from the retardation film to the circularly polarized light separating element, and circular polarization from the retardation film About peeling force QX at 25 ° C. after aging at 150 ° C. for 8 hours until the separation element, the following formula (1):
(PX-P ₁₁ ) <(QX-Q ₁₁ ) (1)
And the first adhesive layer is a cured product of a silicone-based composition.
[2] The following formulas (2) and (3):
P ₁₁ <PX (2)
Q ₁₁ <QX (3)
Wherein the optical member further holds.
[3] P ₁₁ is 0.1～5N / inch, the optical member.
[4] The optical member, wherein the cured product of the silicone composition is formed by curing the silicone composition by an addition reaction.
[5] The optical member, wherein the circularly polarized light separating element is formed by laminating a base material, an alignment film, and a resin layer having cholesteric regularity in this order.
[6] A liquid crystal display device having a liquid crystal panel on the optical member and a surface on the polarizing plate side.

  The optical member of the present invention is based on the fact that the brightness enhancement film and the polarizing plate are integrated, and has the advantage that the device can be thinned and has excellent durability. Even so, the brightness-enhancing film can be easily peeled off, and a liquid crystal display device that can be easily recycled can be provided.

  The optical member of the present invention includes a polarizing plate, a first adhesive layer, a retardation film, a second adhesive layer, and a circularly polarized light separating element.

  A specific example of the optical member of the present invention will be described with reference to FIG. In the example shown in FIG. 1, a polarizing plate 111, a retardation layer 131, and a circularly polarized light separating layer 132 are laminated via a first adhesive layer 121 and a second adhesive layer to constitute the optical member 100 of the present invention. Yes. This is affixed on a substrate 101 such as a liquid crystal panel, and constitutes a part of the components of the liquid crystal display device.

1. Polarizer

The polarizing plate used for this invention is not specifically limited, What coat | covered the protective film with the single side | surface or both surfaces of the well-known polarizer used for the conventional liquid crystal display device etc. can be used.
Examples of the polarizer include those obtained by adsorbing iodine or dichroic dye on a polyvinyl alcohol film and then uniaxially stretching in a boric acid bath, or iodine or dichroic dye on a polyvinyl alcohol film. Examples thereof include those obtained by adsorbing and stretching, and further modifying a part of the polyvinyl alcohol unit in the molecular chain into a polyvinylene unit.

  When natural light is incident on the polarizer used in the present invention, only one polarized light is transmitted. Although the polarization degree of the polarizer used for this invention is not specifically limited, Preferably it is 98% or more, More preferably, it is 99% or more. The average thickness of the polarizer is preferably 5 to 80 μm.

  Examples of the protective film covering the polarizer include cellulose diacetate, cellulose triacetate, alicyclic olefin polymer, acrylic resin, polycarbonate resin, polyethersulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polyethylene methacrylate. Films containing thermoplastic resins such as resins, polysulfone resins, polyethylene resins, polystyrene resins, and polyvinyl chloride resins can be obtained by conventional methods such as lateral uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, and oblique stretching. A stretched one or a stretched one after an optically anisotropic layer is formed on an unstretched thermoplastic resin film can be used. The stretched film may be in the form of a single layer or in the form of a plurality of layers. Among these, cellulose ester, alicyclic olefin polymer, and polymethyl methacrylate resin are preferable due to excellent transparency, and cellulose ester is particularly preferable due to excellent adhesion with the polarizer.

2. Retardation film As a retardation film used in the present invention, (i) a film-like polymer is stretched, or (ii) a liquid crystalline material is applied on a transparent resin substrate, oriented, and cured. Can be used. When using the retardation film of (ii), the retardation film obtained by apply | coating a liquid crystalline material on an appropriate base material, orienting, and hardening can be used.

  Preferred examples of the retardation film used in the present invention include the optically anisotropic elements described below.

  In the present invention, the optically anisotropic element can have a retardation Re in the front direction (hereinafter sometimes abbreviated as “Re”) of approximately ¼ wavelength of transmitted light. Here, the wavelength range of the transmitted light can be a desired range required for the brightness enhancement film of the present invention, and specifically, for example, 400 nm to 700 nm. Further, the retardation Re in the front direction is approximately ¼ wavelength of the transmitted light means that the Re value is ± 65 nm from the ¼ value of the center value in the center value of the wavelength range of the transmitted light, preferably It means ± 30 nm, more preferably ± 10 nm.

The optically anisotropic element desirably has a thickness direction retardation Rth (hereinafter sometimes abbreviated as “Rth”) of less than 0 nm. The value of retardation Rth in the thickness direction is preferably −30 nm to −1000 nm, more preferably −50 nm to −300 nm, in the central value of the wavelength range of transmitted light. By adopting such an optically anisotropic element having an Re value and Rth, it is possible to reduce color unevenness of emitted light while improving brightness and reducing brightness unevenness.
Here, the retardation Re in the front direction is represented by the formula I: Re = (nx−ny) × d (where nx is a direction perpendicular to the thickness direction (front direction) and gives the maximum refractive index). Ny represents a refractive index in a direction perpendicular to the thickness direction (in-plane direction) and perpendicular to nx, and d represents a film thickness). The direction retardation Rth is expressed by the formula II: Rth = {(nx + ny) / 2−nz} × d (where nx is a direction perpendicular to the thickness direction (in-plane direction) and gives the maximum refractive index) Ny is the refractive index in the direction perpendicular to the thickness direction (in-plane direction) and orthogonal to nx, nz is the refractive index in the thickness direction, and d is the film thickness. ).
In addition, the retardation Re in the front direction and the retardation Rth in the thickness direction are measured using a commercially available phase difference measuring apparatus, and the optically anisotropic elements are spaced 100 mm apart in the longitudinal direction and the width direction (longitudinal or lateral length). If the distance is less than 200 mm, three points are specified at equal intervals in that direction), and measurement is performed in a lattice point shape over the entire surface, and the average value is obtained.

  Although the material which comprises the said optically anisotropic element is not specifically limited, What has the layer which consists of a styrene resin can be used preferably. Here, the styrene-based resin is a polymer resin having a styrene structure as a part or all of the repeating unit, and polystyrene, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene. , Styrene monomers such as p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p-phenylstyrene, ethylene, propylene, butadiene, isoprene, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, acrylic acid Examples thereof include copolymers with other monomers such as methyl, methyl methacrylate, ethyl acrylate, ethyl methacrylate, acrylic acid, methacrylic acid, maleic anhydride, and vinyl acetate. Among these, polystyrene or a copolymer of styrene and maleic anhydride can be suitably used.

  The molecular weight of the styrenic resin used for the optically anisotropic element is appropriately selected according to the purpose of use, but is the weight average molecular weight (Mw) of polyisoprene measured by gel permeation chromatography using cyclohexane as a solvent. Usually, 10,000 to 300,000, preferably 15,000 to 250,000, and more preferably 20,000 to 200,000.

  The optically anisotropic element preferably has a laminated structure of a layer made of the styrenic resin and a layer containing another thermoplastic resin. By having the laminated structure, it is possible to provide an element that has both the optical characteristics of the styrene resin and the mechanical strength of other thermoplastic resins. Other thermoplastic resins include alicyclic olefin polymers, methacrylic resins, polycarbonates, acrylic ester-vinyl aromatic compound copolymer resins, methacrylic ester-vinyl aromatic compound copolymer resins, polyethersulfone, etc. Can be mentioned. Among these, a resin having an alicyclic structure or a methacrylic resin can be preferably used.

  The alicyclic olefin polymer is an amorphous olefin polymer having a cycloalkane structure or a cycloalkene structure in the main chain and / or side chain. Specifically, (1) norbornene polymer, (2) monocyclic olefin polymer, (3) cyclic conjugated diene polymer, (4) vinyl alicyclic hydrocarbon polymer, and these A hydride etc. are mentioned. Among these, norbornene-based polymers are more preferable from the viewpoints of transparency and moldability. Examples of the resin having these alicyclic structures include those described in JP-A No. 05-310845, JP-A No. 05-097978, and US Pat. No. 6,511,756.

  Specific examples of the norbornene-based polymer include ring-opening polymers of norbornene-based monomers, ring-opening copolymers of norbornene-based monomers and other monomers capable of ring-opening copolymerization, hydrides thereof, and norbornene-based monomers. And addition copolymers with other monomers copolymerizable with norbornene monomers.

  The methacrylic resin is a polymer having a methacrylic acid ester as a main component, and includes a methacrylic acid ester homopolymer and a copolymer of a methacrylic acid ester and other monomers. Usually, alkyl methacrylate is used. In the case of a copolymer, acrylic acid esters, aromatic vinyl compounds, vinylcyan compounds, etc. are used as other monomers copolymerized with methacrylic acid esters.

  As a preferred specific embodiment of the optically anisotropic element used in the present invention, a multilayer film formed by laminating a film (b layer) made of another thermoplastic resin on both surfaces of a film (a layer) made of polystyrene resin. A stretched multilayer film formed by stretching can be mentioned. Hereinafter, this specific embodiment will be described.

  As the polystyrene resin constituting the a layer, the same “styrene resin” as described above can be used.

  The polystyrene resin constituting the a layer preferably has a glass transition temperature of 120 ° C. or higher, more preferably 120 to 200 ° C., and still more preferably 120 to 140 ° C.

  In the present invention, the polystyrene resin and the other thermoplastic resin have Tg (a)> Tg (b) when their glass transition temperatures are Tg (a) (° C.) and Tg (b) (° C.), respectively. ) It is preferable to satisfy the relationship of + 20 ° C. By satisfying such a relationship, optical anisotropy can be effectively given to the a layer made of polystyrene resin when stretched, and a good optical anisotropic element can be obtained.

  The method of laminating the polystyrene 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 multilayer film is not particularly limited, but is a coextrusion T-die method, coextrusion inflation Known methods such as a method of forming by coextrusion such as a method, a coextrusion lamination method, a film lamination forming method such as dry lamination, and a coating forming method may be appropriately used. Among these, a molding method by coextrusion is preferable from the viewpoints of production 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 polystyrene resin used and the other thermoplastic resin.

  The multilayer film is formed by laminating the b layer on both surfaces of the a layer. An adhesive layer or a pressure-sensitive adhesive layer can be provided between the a layer and the b layer, but the a layer and the b layer are directly laminated (that is, lamination of a three-layer configuration of b layer / a layer / b layer). Body). In the multilayer film, the 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.

The stretched multilayer film is formed by stretching the multilayer film. The stretched multilayer film may include an A layer provided by stretching the a layer and a B layer provided by stretching the b layer. The stretched multilayer film is a stretched film having a three-layer structure of B layer / A layer / B layer formed by stretching a laminate of b layer / a layer / b layer of the multilayer film. It is preferable.
The stretching can be preferably performed by uniaxial stretching or oblique stretching, and more preferably by uniaxial stretching or oblique stretching by a tenter.

  The front direction retardation Re and the thickness direction retardation Rth of the optically anisotropic element 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, and more preferably in the range of Tg (a) -5 ° C to Tg (a) + 15 ° C. The draw ratio is preferably 1.05 to 30 times, and more preferably 1.1 to 10 times. If the stretching temperature and the stretching ratio are out of the above ranges, the orientation may be insufficient and the refractive index anisotropy and thus the retardation may be insufficiently developed, or the laminate may be broken.

  The thickness of the optically anisotropic element is preferably 50 to 1000 μm, more preferably 50 to 600 μm.

  When used in the present invention, the retardation film can be subjected to surface treatment such as corona discharge treatment, plasma treatment, UV ozone treatment, and EB treatment on one or both surfaces thereof. By applying such a surface treatment, a desired peel strength of the present invention described later can be obtained.

3. Circularly polarized light separating element The circularly polarized light separating element used in the present invention refers to an element that reflects only circularly polarized light of a specific wavelength and transmits the remaining circularly polarized light among incident natural light. The reflected light can be reused by re-entering the resin layer with a reflector or the like, and in particular, a combination of a circularly polarized light separating element and a quarter-wave plate as a retardation film, Natural light can be converted into linearly polarized light with high efficiency.

  Preferred examples of the circularly polarized light separating element used in the present invention include those having a resin layer having the cholesteric regularity described below (hereinafter sometimes simply referred to as “cholesteric resin layer”).

  The cholesteric regularity of the cholesteric resin layer in the optical member of the present invention means that the molecular axes are aligned in a certain direction on one plane, but the direction of the molecular axes is slightly shifted on the next plane, The structure is such that the angle of the molecular axis is shifted (twisted) as it advances through the plane in which molecules are arranged in a certain direction, such that the angle is further shifted in the next plane. Thus, the structure in which the direction of the molecular axis is twisted becomes an optically chiral structure.

  A resin having cholesteric regularity has a circularly polarized light separation function. That is, it has a function of transmitting left-rotated or right-rotated circularly polarized light in a specific wavelength region and reflecting other circularly polarized light.

  In this invention, it is preferable to provide the cholesteric resin layer which exhibits this circularly polarized light separation function over the entire wavelength region of visible light. For example, a cholesteric resin layer having a circularly polarized light separation function is preferable for light in any wavelength region of blue (wavelength 410 to 470 nm), green (wavelength 520 to 580 nm), and red (wavelength 600 to 660 nm).

  The wavelength that exhibits the circularly polarized light separation function depends on the pitch of the chiral structure in the cholesteric resin. The pitch of the chiral structure is a distance in the plane normal direction until the angle of the molecular axis in the chiral structure gradually shifts as it advances along the plane and then returns to the original molecular axis direction again. By changing the pitch of this chiral structure, the wavelength at which the circularly polarized light separating function is exhibited can be changed.

  The cholesteric resin layer used in the present invention is preferably a non-liquid crystalline resin layer. This is because the cholesteric regularity does not change depending on the ambient temperature, electric field, or the like when it is non-liquid crystalline. The non-liquid crystalline cholesteric resin layer can be obtained by aligning the liquid crystalline compound in a cholesteric liquid crystal phase and then polymerizing the liquid crystalline compound in a composition layer containing a liquid crystalline and polymerizable compound.

  As the cholesteric resin layer used in the present invention, for example, (i) a cholesteric resin layer in which the pitch of the chiral structure is changed stepwise, and (ii) the pitch of the chiral structure is continuously changed. A cholesteric resin layer etc. are mentioned.

  (I) The cholesteric resin layer in which the pitch of the chiral structure is changed stepwise includes, for example, a cholesteric resin layer having a chiral structure pitch that exhibits a circularly polarized light separation function with light in a blue wavelength range, It can be obtained by laminating a cholesteric resin layer having a chiral structure pitch that exhibits a circularly polarized light separating function with light and a cholesteric resin layer having a chiral structure pitch that exhibits a circularly polarized light separating function with light in the red wavelength region. it can. Further, cholesteric resin layers having a central wavelength of reflected circularly polarized light of 470 nm, 550 nm, 640 nm, and 770 nm are respectively produced, and these cholesteric resin layers are arbitrarily selected, and the order of the central wavelengths of reflected light is 3 to 3 It can be obtained by laminating seven layers. When the cholesteric resin layers having different chiral structure pitches are laminated, it is preferable that the rotation directions of the circularly polarized light reflected by the cholesteric resin layers are the same. In addition, in order to obtain a liquid crystal display device having a wide viewing angle, the stacking order of the cholesteric resin layers having different chiral structure pitches may be ascending or descending in order of the chiral structure pitch. preferable. The lamination of these cholesteric resin layers may be merely overlaid, or may be fixed via an adhesive or an adhesive.

  (Ii) The cholesteric resin layer in which the pitch of the chiral structure is continuously changed is not particularly limited by its manufacturing method, but as a preferable example of the manufacturing method of such a cholesteric resin layer, a cholesteric resin layer is formed. A cholesteric liquid crystal composition containing a polymerizable liquid crystal compound for coating is preferably applied on another layer such as an alignment film to obtain a liquid crystal layer, and then subjected to light irradiation and / or heating treatment at least once. A method of curing the liquid crystal layer can be mentioned. Preferable embodiments of the cholesteric liquid crystal composition include cholesteric liquid crystal composition (X) described in detail below.

The cholesteric liquid crystal composition (X) contains a compound represented by the following general formula (1) and a specific rod-like liquid crystal compound. Each of these components will be described in turn.
R ¹ -A ¹ -BA ² -R ² (1)

In General Formula (1), R ¹ and R ² are each independently a linear or branched alkyl group having 1 to 20 carbon atoms, or a linear or branched chain having 1 to 20 carbon atoms. And a group selected from the group consisting of a hydrogen atom, a halogen atom, a hydroxyl group, a carboxyl group, a (meth) acryl group, an epoxy group, a mercapto group, an isocyanate group, an amino group, and a cyano group. Here, (meth) acryl means acryl and methacryl.

  The alkyl group and alkylene oxide group may be unsubstituted or substituted with one or more halogen atoms. The halogen atom, hydroxyl group, carboxyl group, (meth) acryl group, epoxy group, mercapto group, isocyanate group, amino group, and cyano group are bonded to an alkyl group having 1 to 2 carbon atoms or an alkylene oxide group. May be.

Preferable examples of R ¹ and R ² include a halogen atom, hydroxyl group, carboxyl group, (meth) acryl group, epoxy group, mercapto group, isocyanate group, amino group, and cyano group.

Moreover, it is preferable that at least one of R ¹ and R ² is a reactive group. By having a reactive group as R ¹ and / or R ² , the compound represented by the general formula (1) is fixed in the liquid crystal layer at the time of curing, and a stronger film can be formed. Here, examples of the reactive group include a carboxyl group, a (meth) acryl group, an epoxy group, a mercapto group, an isocyanate group, and an amino group.

In the general formula (1), A ¹ and A ² are each independently 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, 4,4′-biphenylene group, 4, It represents a group selected from the group consisting of a 4′-bicyclohexylene group and a 2,6-naphthylene group. The 1,4-phenylene group, 1,4-cyclohexylene group, 1,4-cyclohexenyl group, 4,4′-biphenylene group, 4,4′-bicyclohexylene group, and 2,6-naphthylene group are , It may be unsubstituted or substituted with one or more halogen atoms, hydroxyl groups, carboxyl groups, cyano groups, amino groups, alkyl groups having 1 to 10 carbon atoms, or halogenated alkyl groups. In each of A ¹ and A ² , when two or more substituents are present, they may be the same or different.

Particularly preferred examples of A ¹ and A ² include groups selected from the group consisting of 1,4-phenylene group, 4,4′-biphenylene group, and 2,6-naphthylene group. These aromatic ring skeletons are relatively rigid as compared with the alicyclic skeletons, have high affinity with the mesogens of rod-like liquid crystalline compounds described later, and have higher alignment uniformity.

In the general formula (1), B represents a single bond, —O—, —S—, —S—S—, —CO—, —CS—, —OCO—, —CH ₂ —, —OCH ₂ —, —C. = N-N = C -, - NHCO -, - OCOO -, - CH 2 COO-, and is selected from the group consisting of -CH ₂ OCO-.

  Particularly preferable examples of B include a single bond, —OCO—, and —C═N—N═C—.

  As for the compound of General formula (1), it is preferable that at least 1 type has liquid crystallinity, and it is preferable to have chirality. The cholesteric liquid crystal composition (X) preferably contains a mixture of a plurality of optical isomers as the compound of the general formula (1). For example, a mixture of plural kinds of enantiomers and / or diastereomers can be contained. At least one of the compounds of the general formula (1) preferably has a melting point in the range of 50 ° C to 150 ° C.

  When the compound of the general formula (1) has liquid crystallinity, a high Δn is preferable. By containing the high Δn liquid crystal, Δn as the cholesteric liquid crystal composition (X) can be improved, and a broadband circularly polarized light separating sheet can be produced. At least one Δn of the compound of the general formula (1) is preferably 0.18 or more, more preferably 0.22 or more.

  Specific examples of particularly preferred compounds of the general formula (1) include the following compounds (A1) to (A3) and (A5) to (A10):

  In the compound (A3), “*” represents a chiral center.

The cholesteric liquid crystal composition (X) contains a rod-like liquid crystal compound having Δn of 0.18 or more and having at least two or more reactive groups in one molecule.
Examples of the rod-like liquid crystalline compound include compounds represented by the formula (2).
^{R 3 -C 3 -D 3 -C 5} -M-C 6 -D 4 -C 4 -R 4 Formula (2)
(Wherein R ³ and R ⁴ are reactive groups, each independently (meth) acryl group, (thio) epoxy group, oxetane group, thietanyl group, aziridinyl group, pyrrole group, vinyl group, allyl group, D ³ and D ⁴ each represent a group selected from the group consisting of 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. A group selected from the group consisting of a bond, a linear or branched alkyl group having 1 to 20 carbon atoms, and a linear or branched alkylene oxide group having 1 to 20 carbon atoms; C ^{3 to} C ⁶ are a single bond, —O—, —S—, —S—S—, —CO—, —CS—, —OCO—, —CH ₂ —, —OCH ₂ —, —C═. N—N═C—, —NHCO— _{, -OCOO -, - CH 2 COO-} , and .M represents a group selected from the group consisting of -CH ₂ OCO- represents a mesogenic group, specifically, have a unsubstituted or substituted group Azomethines, azoxys, phenyls, biphenyls, terphenyls, naphthalenes, anthracenes, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted Two to four skeletons selected from the group of phenylpyrimidines, phenyldioxanes, tolanes, and alkenylcyclohexylbenzonitriles are converted to —O—, —S—, —S—S—, —CO—, —CS. -, - OCO -, - CH 2 -, - OCH 2 -, - C = N-N = C -, - NHCO -, - OCOO -, - C ₂ COO-, and is formed are joined by a linking group of -CH ₂ OCO-, and the like.)
Examples of the substituent that the mesogenic group M may have include a halogen atom, an optionally substituted alkyl group having 1 to 10 carbon atoms, a cyano group, a nitro group, —O—R ⁵ , —O—C. (═O) —R ⁵ , —C (═O) —O—R ⁵ , —O—C (═O) —O—R ⁵ , —NR ⁵ —C (═O) —R ⁵ , —C ( = O) -NR < ⁵ > R < ⁷ > or -O-C (= O) -NR < ⁵ > R < ⁷ >. Wherein, R ⁵ and ^{R 7} represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, when it is alkyl group, and the alkyl group, -O -, - S -, - O-C (= O) —, —C (═O) —O—, —O—C (═O) —O—, —NR ⁶ —C (═O) —, —C (═O) —NR ⁶ —, —NR ^6- or -C (= O)-may be present (except when two or more of -O- and -S- are present adjacent to each other). Wherein, R ⁶ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms. Examples of the substituent in the “optionally substituted alkyl group having 1 to 10 carbon atoms” include a halogen atom, a hydroxyl group, a carboxyl group, a cyano group, an amino group, and an alkoxy group having 1 to 6 carbon atoms. Group, alkoxyalkoxy group having 2 to 8 carbon atoms, alkoxyalkoxyalkoxy group having 3 to 15 carbon atoms, alkoxycarbonyl group having 2 to 7 carbon atoms, alkylcarbonyloxy having 2 to 7 carbon atoms Group, an alkoxycarbonyloxy group having 2 to 7 carbon atoms, and the like.
In the present invention, the rod-like liquid crystalline 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 (2) with the mesogenic group M as the center. Say. By using a rod-like liquid crystal compound having an asymmetric structure, alignment uniformity can be further improved.

  In the present invention, the rod-like liquid crystal compound has a Δn value of 0.18 or more, preferably 0.22 or more. When a compound having an Δn 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 desired optical performance even when the absorption edge of the spectrum extends to the visible range. It can be used as long as it does not adversely affect By having such a high Δn value, a circularly polarized light separating sheet having high optical performance (for example, circularly polarized light separating characteristics) can be provided.

  In the present invention, the rod-like liquid crystalline compound has at least two or more reactive groups in one molecule. Specific examples of the reactive group include an epoxy group, a thioepoxy group, an oxetane group, a thietanyl group, an aziridinyl group, a pyrrole group, a fumarate group, a cinnamoyl group, an isocyanate group, an isothiocyanate group, an amino group, a hydroxyl group, and a carboxyl group. , Alkoxysilyl groups, oxazoline groups, mercapto groups, vinyl groups, allyl groups, methacryl groups, and acrylic groups. By having these reactive groups, a stable cured product can be obtained when the cholesteric liquid crystal composition is cured. When a compound having one or less reactive group in one molecule is used, when the cholesteric liquid crystal 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 be practically used is HB or more, preferably H or more, in pencil hardness (JIS K5400). If the film strength is lower than HB, the film is easily scratched and lacks handling properties. The upper limit of preferable pencil hardness is not particularly limited as long as it does not adversely affect the optical performance and durability test.

  In the cholesteric liquid crystal composition (X), the weight ratio of (total weight of the compound of the general formula (1)) / (total weight of the rod-like liquid crystal compound) is 0.05 to 1, preferably 0.1 to 0. .65, more preferably 0.15 to 0.45. When the weight ratio is less than 0.05, the alignment uniformity may be insufficient. On the other hand, when the weight ratio is more than 1, the alignment uniformity decreases, the stability of the liquid crystal phase decreases, and the liquid crystal composition As a result, the desired optical performance (for example, circularly polarized light separation characteristics) may not be obtained. The total weight indicates the weight when one kind is used and the total weight when one or more kinds are used.

  In the cholesteric liquid crystal composition (X), the compound of the general formula (1) preferably has a molecular weight of less than 600, and the rod-like liquid crystal compound has a molecular weight of 600 or more. When the molecular weight of the compound of the general formula (1) is less than 600, it can enter the gap between the rod-like liquid crystalline compounds having a molecular weight larger than that, and the alignment uniformity can be improved.

In the present invention, the cholesteric liquid crystal composition such as the cholesteric liquid crystal composition (X) can optionally contain a cross-linking agent in order to improve the film strength and durability after curing. As the cross-linking agent, it reacts simultaneously when the liquid crystal layer coated with the liquid crystal composition is cured, or heat treatment is performed after curing to accelerate the reaction, or the reaction proceeds spontaneously by moisture to increase the crosslinking density of the liquid crystal layer. Those that can be enhanced and that do not deteriorate the alignment uniformity can be appropriately selected and used, and those that are cured by ultraviolet rays, heat, moisture, etc. can be suitably used. Specific examples of the crosslinking agent include, for example, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 2- (2-vinyl Polyfunctional acrylate compounds such as loxyethoxy) ethyl acrylate; epoxy compounds such as glycidyl (meth) acrylate, ethylene glycol diglycidyl ether, glycerin triglycidyl ether, pentaerythritol tetraglycidyl ether; 2,2-bishydroxymethylbutanol-tris [ 3- (1-aziridinyl) propionate], 4,4-bis (ethyleneiminocarbonylamino) diphenylmethane, trimethylolpropane-tri-β-aziridinini Aziridine compounds such as lupropionate; Isocyanurate type isocyanates derived from hexamethylene diisocyanate, hexamethylene diisocyanate, isocyanurate type isocyanates, biuret type isocyanates, adduct type isocyanates; polyoxazoline compounds having an oxazoline group in the side chain; vinyltrimethoxysilane; N- (2-aminoethyl) 3-aminopropyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, N- (1 , 3-dimethylbutylidene) -3- (triethoxysilyl) -1-propanamine and the like alkoxysilane compounds. Moreover, a well-known catalyst can be used according to the reactivity of this crosslinking agent, and productivity can be improved in addition to an improvement in film strength and durability.
The blending ratio of the crosslinking agent is preferably 0.1 to 15% by weight in a cured film obtained by curing the cholesteric liquid crystal composition. When the blending ratio of the crosslinking agent is less than 0.1% by weight, the effect of improving the crosslinking density cannot be obtained. Conversely, when the blending ratio is more than 15% by weight, the stability of the liquid crystal layer is lowered, which is not preferable.

In the present invention, the cholesteric liquid crystal composition can optionally contain a photoinitiator. As the photoinitiator, known compounds that generate radicals or acids by ultraviolet rays or visible rays can be used. Specifically, benzoin, benzylmethyl ketal, benzophenone, biacetyl, acetophenone, Michler's ketone, benzyl, benzylisobutyl ether, tetramethylthiuram mono (di) sulfide, 2,2-azobisisobutyronitrile, 2,2-azobis -2,4-dimethylvaleronitrile, benzoyl peroxide, di-tert-butyl peroxide, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenyl-propan-1-one, 1- (4 -Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-diethylthioxanthone, methylbenzoyl formate, 2,2-dieto Cyacetophenone, β-ionone, β-bromostyrene, diazoaminobenzene, α-amylcinnac aldehyde, p-dimethylaminoacetophenone, p-dimethylaminopropiophenone, 2-chlorobenzophenone, pp′-dichlorobenzophenone, pp ′ -Bisdiethylaminobenzophenone, benzoin ethyl ether, benzoin isopropyl ether, benzoin n-propyl ether, benzoin n-butyl ether, diphenyl sulfide, bis (2,6-methoxybenzoyl) -2,4,4-trimethyl-pentylphosphine oxide, 2,4,6-trimethylbenzoyldiphenyl-phosphine oxide, bis (2,4,6-trimethylbenzoyl) -phenylphosphine oxide, 2-methyl-1 [ 4- (Methylthio) phenyl] -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, anthracenebenzophenone, α-chloroanthraquinone , Diphenyl disulfide, hexachlorobutadiene, pentachlorobutadiene, octachlorobutene, 1-chloromethylnaphthalene, 1,2-octanedione, 1- [4- (phenylthio) -2- (o-benzoyloxime)] and 1- Carbazole oxime compounds such as [9-ethyl-6- (2-methylbenzoyl) -9H-carbazol-3-yl] ethanone 1- (o-acetyloxime), (4-methylphenyl) [4- (2-methyl Propyl) phenyl] iodonium hexafluorophosphate, 3-methyl- - butynyl tetramethyl hexafluoroantimonate, diphenyl - (p-phenylthiophenyl) sulfonium hexafluoroantimonate, and the like. In addition, two or more compounds can be mixed depending on the desired physical properties, and if necessary, a known photosensitizer or a tertiary amine compound as a polymerization accelerator is added to control curability. You can also.
The blending ratio of the photoinitiator is preferably 0.03 to 7% by weight in the cholesteric liquid crystal composition. When the blending amount of the photoinitiator is less than 0.03% by weight, the degree of polymerization is lowered and the film strength may be lowered. On the other hand, if it is more than 7% by weight, the alignment of the liquid crystal is inhibited and the liquid crystal phase may become unstable.

  In the present invention, the cholesteric liquid crystal composition can optionally contain a surfactant. As the surfactant, those not inhibiting the orientation can be appropriately selected and used. As the surfactant, specifically, a nonionic surfactant containing siloxane or fluorinated alkyl group in the hydrophobic group portion can be preferably used, and an oligomer having two or more hydrophobic group portions in one molecule. Is particularly preferred. These surfactants are OMNOVA PolyFox PF-151N, PF-636, PF-6320, PF-656, PF-6520, PF-3320, PF-651, PF-652, Neos's Fantgent FTX- 209F, FTX-208G, FTX-204D, Seimi Chemical's Surflon KH-40, and the like can be used. The blending ratio of the surfactant is preferably 0.05% by weight to 3% by weight in the cured film obtained by curing the cholesteric liquid crystal composition. When the blending ratio of the surfactant is less than 0.05% by weight, the orientation regulating force at the air interface is lowered and an orientation defect may occur, which is not preferable. On the other hand, when the amount is more than 3% by weight, it is not preferable because an excessive surfactant may enter between liquid crystal molecules and lower the alignment uniformity.

  In the present invention, the cholesteric liquid crystal composition can optionally contain a chiral agent. Specific examples of the chiral agent include JP-A-2005-289881, JP-A-2004-115414, JP-A-2003-66214, JP-A-2003-313187, JP-A-2003-342219, JP-A-2000-290315, JP-A-6-072962, U.S. Pat. No. 6,468,444, WO98 / 00428, JP-A-2007-176870, etc. can be used as appropriate. For example, it can be obtained as LC756 of BASF Corporation Paliocolor.

  The chiral agent can be added within a range that does not deteriorate the desired optical performance. The content ratio of the chiral agent is usually 1 to 60% by weight in the cholesteric liquid crystal composition.

  In the present invention, the cholesteric liquid crystal composition can further contain other optional components as necessary. Examples of the other optional components include a solvent, a polymerization inhibitor for improving pot life, an antioxidant for improving durability, an ultraviolet absorber, and a light stabilizer. These optional components can be added as long as the desired optical performance is not deteriorated.

  The method for producing the cholesteric liquid crystal composition in the present invention is not particularly limited, and can be produced by mixing the above-described components.

  A cholesteric liquid crystal composition such as the cholesteric liquid crystal composition (X) is applied onto another layer such as an alignment film to obtain a liquid crystal layer, and then the liquid crystal is subjected to light irradiation and / or heating treatment at least once. A cholesteric resin layer can be obtained by curing the layer. The application can be carried out by a known method such as an extrusion coating method, a direct gravure coating method, a reverse gravure coating method, a die coating method, or a bar coating method.

  Before the liquid crystal layer obtained by the application is cured, an alignment treatment can be performed as necessary. The alignment treatment can be performed, for example, by heating the liquid crystal layer at 50 to 150 ° C. for 0.5 to 10 minutes. By performing the alignment treatment, the cholesteric liquid crystal layer can be aligned well.

The curing step can be performed by a combination of one or more light irradiations and a heating treatment. Specifically, the heating condition is, for example, a temperature of 40 to 200 ° C., preferably 50 to 200 ° C., more preferably 50 to 140 ° C., and a time of 1 second to 3 minutes, preferably 5 to 120 seconds. it can. The light used for light irradiation in the present invention 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 second to 3 minutes. Further, for example, a weakly irradiated ultraviolet ray of 0.01 to 50 mJ / cm ² and heating may be alternately repeated several times to obtain a circularly polarized light separating sheet having a wide reflection band. After extending the reflection band by the above-mentioned weak ultraviolet irradiation, etc., a relatively strong ultraviolet ray of 50 to 10,000 mJ / cm ² is irradiated to completely polymerize the liquid crystalline compound to form a cholesteric resin layer. it can. The expansion of the reflection band and the irradiation with strong ultraviolet rays may be performed in the air, or a part or all of the process may be performed in an atmosphere in which the oxygen concentration is controlled (for example, in a nitrogen atmosphere). .

  In the present invention, the step of applying and curing the cholesteric liquid crystal composition on another layer such as an alignment film is not limited to one time, and the coating and curing are repeated a plurality of times to form two or more cholesteric resin layers. You can also. However, in the present invention, even when the cholesteric liquid crystal composition is applied and cured only once, a cholesteric resin layer having a well-oriented rod-like liquid crystalline compound having a Δn of 0.18 or more and a thickness of 5 μm or more can be easily formed. Can be formed.

  In the optical member of the present invention, the dry film thickness of the cholesteric resin layer is preferably 3.0 μm to 10.0 μm, more preferably 3.5 to 8 μm. When the dry film thickness of the cholesteric resin layer is less than 3.0 μm, the reflectance decreases, and conversely, when thicker than 10.0 μm, the cholesteric resin layer is colored when observed from an oblique direction, Each is not preferred. The dry film thickness refers to the total film thickness of each layer when the cholesteric resin layer is two or more layers, and the film thickness when the cholesteric resin layer is one layer.

  The circularly polarized light separating element used in the present invention can further include the above-described base material layer and alignment film as necessary.

  The said base material layer can be comprised with a transparent resin base material. The transparent resin substrate is not particularly limited, and a substrate having a thickness of 1 mm and a total light transmittance of 80% or more can be used. Specifically, alicyclic olefin polymers, chain olefin polymers such as polyethylene and polypropylene, triacetyl cellulose, polyvinyl alcohol, polyimide, polyarylate, polyester, polycarbonate, polysulfone, polyethersulfone, modified acrylic polymer, epoxy resin, Examples thereof include a single layer or laminated film made of a synthetic resin such as polystyrene or acrylic resin. Among these, an alicyclic olefin polymer or a chain olefin polymer is preferable, and an alicyclic olefin polymer is particularly preferable from the viewpoint of transparency, low hygroscopicity, dimensional stability, lightness, and the like.

The alignment film can be provided on the base material layer. By providing the alignment film, the cholesteric liquid crystal composition applied thereon can be aligned in a desired direction. The alignment film is subjected to a corona discharge treatment, if necessary, on the surface of the substrate, and then a solution obtained by dissolving the alignment film material in water or a solvent, reverse gravure coating, direct gravure coating, die coating, It can be formed by applying and drying using a known method such as bar coating and then subjecting the dried coating film to a rubbing treatment. As materials for the alignment film, cellulose, silane coupling agent, polyimide, polyamide, polyvinyl alcohol, epoxy acrylate, silanol oligomer, polyacrylonitrile, phenol resin, polyoxazole, cyclized polyisoprene, etc. can be used. Polyamide is particularly preferred.
Examples of the modified polyamide include those obtained by modifying an aromatic polyamide or an aliphatic polyamide, and those obtained by modifying an aliphatic polyamide are preferred. Specifically, for example, modified to nylon-6, nylon-66, nylon-12, ternary to quaternary copolymer nylon, fatty acid polyamide, or fatty acid block copolymer (for example, polyether ester amide, polyester amide). Can be mentioned. Examples of the modification include terminal amino modification, carboxyl modification, hydroxyl modification and the like, and modification in which a part of the amide group is alkylaminated or N-alkoxyalkylated. Examples of the N-alkoxyalkylated modified polyamide include N-methoxymethylated part of the amide group of a copolymer nylon such as nylon-6, nylon-66, or nylon-12. The weight average molecular weight of the modified polyamide is preferably 5,000 to 500,000, more preferably 10,000 to 200,000.
The thickness of the alignment film may be any film thickness that provides the desired alignment uniformity of the liquid crystal layer, and is preferably 0.001 to 5 μm, and more preferably 0.01 to 2 μm.

4). Adhesive layer The optical member of the present invention comprises a first adhesive layer interposed between the polarizing plate and the retardation film, and a second adhesive layer interposed between the retardation film and the circularly polarized light separating element. Have.

In the optical member of the present invention, the first adhesive layer is a cured product of a silicone-based composition. Here, the silicone-based composition is a composition containing a compound having a siloxane bond (Si—O—Si) as an essential component. More specifically, it can be a compound having a repeating unit of-(Si (R ^1S ) (R ^2S ) -O)-and having a hydrogen atom, a hydroxyl group or an organic group described later at the terminal. Here, R ^1S and R ^2S can be independently a hydrogen atom or an organic group. Examples of the organic group include alkyl groups such as methyl group and ethyl group, substituted alkyl groups such as chloropropyl group and trifluoropropyl group, alkenyl groups such as vinyl group and allyl group, and aryl groups such as phenyl group. However, organopolysiloxanes having a methyl group, a phenyl group or the like as R ^1S and R ^2S are particularly preferable from an industrial viewpoint.
Examples of the composition include an addition reaction type silicone pressure sensitive adhesive and a radical curable type silicone pressure sensitive adhesive. These can be used with one or more curing agents. Examples of the curing agent for the addition reaction type silicone pressure-sensitive adhesive include hydrosilylation catalysts such as a platinum-based catalyst, a palladium-based catalyst, and a rhodium-based catalyst. Examples of the curing agent for the radical-curable silicone pressure-sensitive adhesive include benzoyl peroxide, Examples thereof include peroxide catalysts such as 2,4-dichlorobenzoyl peroxide, 4-monochlorobenzoyl peroxide, dicumyl peroxide, and t-butyl peroxide.
The addition amount of the hydrosilylation catalyst in the first adhesive layer is 0.1 to 5 parts by weight, particularly 0.5 to 2.0 parts by weight based on 100 parts by weight of the silicone composition. The addition amount of the peroxide catalyst is 0.05 to 5 parts by weight, particularly 0.2 to 1.5 parts by weight, based on 100 parts by weight of the silicone composition. When the addition amount of the curing agent is small, sufficient curing cannot be obtained, and when it is large, problems such as discoloration of the pressure-sensitive adhesive occur.
Specific examples of the addition reaction type silicone adhesive include: Toray Dow Corning; SD4560, SD4570, SD4592, Shin-Etsu Chemical; X-40-3229, X-40-3270, radical curing type silicone adhesive Specific examples include SH4280 and SD4284 manufactured by Toray Dow Corning.

The method for curing such a silicone-based composition is not particularly limited, but after mixing the respective components constituting the composition and the curing agent as necessary, the range that does not impair the purpose of the present invention, if necessary. In the method, an auxiliary such as an organic solvent, an adhesion improver, a filler, an ultraviolet absorber, a radical scavenger or the like is added, dried and heated.
The organic solvent is not particularly limited as long as it can dissolve the above composition uniformly, specifically, aromatic hydrocarbons such as toluene and xylene; aliphatic hydrocarbons such as hexane and heptane; acetone And ketone systems such as methyl ethyl ketone.

  In the optical member of the present invention, the cured product of the silicone composition is that the silicone composition is cured by an addition reaction, and can be cured at a lower temperature and in a shorter time. Preferred from the above advantages.

  In the optical member of the present invention, the material constituting the second adhesive layer is not particularly limited, but an acrylic solvent-type adhesive, an acrylic emulsion-type adhesive, a urethane-based solvent-type adhesive, an ethylene-vinyl acetate hot melt Adhesives such as adhesives and epoxy adhesives can be preferably used. Specific examples of such acrylic solvent-type pressure-sensitive adhesives and acrylic emulsion-type pressure-sensitive adhesives include Soken Kagaku; SK Dyne 2094, manufactured by Daido Kasei; Vinizol E-5301. You may add auxiliary agents, such as a hardening | curing agent, as needed.

In the optical member of the present invention, the initial peel force P ₁₁ at 25 ° C. and the peel force Q ₁₁ at 25 ° C. after aging at 150 ° C. for 8 hours at the interface between the polarizing plate and the first adhesive layer, the retardation film The initial peeling force PX at 25 ° C. from the circularly polarized light separating element to the circularly polarized light separating element and the peeling force QX at 25 ° C. after aging at 150 ° C. for 8 hours from the retardation film to the circularly polarized light separating element (1):
(PX-P ₁₁ ) <(QX-Q ₁₁ ) (1)
Holds. In addition, the following formulas (2) and (3):
P ₁₁ <PX (2)
Q ₁₁ <QX (3)
Is more preferable.

  Thus, by making the peeling force before and after aging predetermined, it becomes possible to easily recycle the product. Furthermore, when the initial peeling force satisfies the above formula (2), not only the peeling in recycling after use of the product but also the work of reworking defective products at the time of manufacturing the product, that is, the work of reworking is facilitated.

  Specifically, as shown in FIG. 3, the laminated body 302 including the retardation film 131 and the circularly polarized light separating element 132 is held and peeled in a state where the laminated body 301 of the substrate 101 and the polarizing plate 111 is fixed. The laminate 302 can be peeled off satisfactorily. On the other hand, in the case of a laminated body that does not have the above-described features of the present invention, for example, as shown in FIG. Arise.

  Here, the peeling force “between the retardation film and the circularly polarized light separating element” means that the optical member of the present invention is peeled by holding the circularly polarized light separating element while the retardation film is fixed. It is the peeling force at the time. The peel force between the retardation film and the circularly polarized light separating element is the peel force at the interface between the retardation film and the second adhesive layer, and the peel force at the interface between the second adhesive layer and the circularly polarized light separating element. Depends on the smaller one.

“Initial” peel force is the peel force when left at a temperature of 25 ° C. and a humidity of 60% for 24 hours immediately after the production of the optical member, whereas the peel force after aging at 150 ° C. for 8 hours is the peel force immediately after production. It refers to the peel force measured in the same manner as the measurement of the initial peel force after the optical member was immediately aged in an environment at a temperature of 150 ° C. for 8 hours.
The peel force is a value measured at a constant speed (300 mm / min) using a tensile tester in accordance with JIS Z0237.

Specific values of the peel force P ₁₁ and _{Q 11} is not particularly _limited, it is preferably _{P 11} is 0.1～5N / inch. Meanwhile specific values of _{Q 11} is not particularly limited, it is preferable that 7.5～25N / inch.

In the optical member of the present invention, the initial peeling force P ₁₂ at 25 ° C. at the interface between the first adhesive layer and the retardation film and 150 ° C. at the interface between the first adhesive layer and the retardation film are further provided. for peel force _{Q 12} after 8 hours aging, the following formula (4) and (5):
P ₁₁ <P ₁₂ (4)
Q ₁₁ <Q ₁₂ (5)
The relationship holds. By having such a relationship, the properties of the release surface can be made better.

  In this invention, it is preferable that the thickness of a 1st adhesion layer is 5-30 micrometers. On the other hand, the thickness of the second adhesive layer is preferably 2 to 50 μm. By making the thickness within the range, peeling can be made easier.

5. Other Layers The optical member of the present invention has, as a basic configuration, a layer configuration of polarizing plate / first adhesive layer / retardation film / second adhesive layer / circularly polarized light separating element. In addition to the first circularly polarized light separating element, the second circularly polarized light separating element has a third adhesive layer therebetween, that is, a polarizing plate / first adhesive layer / retardation film / second film. It may have a layer configuration of 2 adhesive layers / first circularly polarized light separating element / third adhesive layer / second circularly polarized light separating element. Specifically, as in the example illustrated in FIG. 2, in addition to the polarizing plate 111, the first adhesive layer 121, the retardation film 131, the second adhesive layer 122, and the first circularly polarized light separating element 132, the third adhesive A configuration like the optical member 200 including the layer 123 and the second circularly polarized light separating element 133 can be employed.

  As this 3rd adhesion layer, the layer which consists of the same material as what comprises a 2nd adhesion layer can be used. The first circularly polarized light separating element and the second circularly polarized light separating element can be elements having different selective reflection bands by changing the manufacturing conditions. By using them in combination, selective reflection over a wide band can be achieved.

  The optical member of the present invention can be provided with a third circularly polarized light separating element via a fourth adhesive layer in addition to the second circularly polarized light separating element, if necessary. It is also possible to provide four or more circularly polarized light separating elements.

6). Liquid Crystal Display Device The liquid crystal display device of the present invention includes the optical member of the present invention and a liquid crystal panel attached to the optical member via the surface of the optical member on the polarizing plate side. More specifically, among the polarizing plates provided on both surfaces of the liquid crystal panel, the polarizing plate far from the viewing side is replaced with the optical member of the present invention, and light from a light source such as a backlight device is a circularly polarized light separating element. A device that transmits light in the order of retardation film → polarizing plate → liquid crystal panel → polarizing plate can be configured. With this configuration, it is possible to reduce the thickness of the apparatus while suppressing the luminance improvement by the circularly polarized light separating element and the retardation film, to suppress deterioration over time, and to facilitate product recycling.

  The liquid crystal panel is not particularly limited, and those used in liquid crystal display devices can be used as appropriate. For example, TN (Twisted Nematic) type liquid crystal panel, STN (Super Twisted Nematic) type liquid crystal panel, HAN (Hybrid Alignment Nematic) type liquid crystal panel, IPS (In Plane Switching) type liquid crystal panel, VA (vertical type liquid crystal panel). Examples thereof include a MVA (Multiple Vertical Alignment type liquid crystal panel) and an OCB (Optical Compensated Bend) type liquid crystal panel.

  Hereinafter, the present invention will be described in more detail based on examples. In addition, this invention is not limited to the following Example.

(Example 1: Production of a brightness enhancement film having a cholesteric resin layer of 1 layer)
(1-1: Preparation of first circularly polarized light separating element)
Both surfaces of a film made of an alicyclic olefin polymer (manufactured by Optes Co., Ltd .; trade name “Zeonor film ZF14-100”) were subjected to corona discharge treatment. An aqueous solution of 5 wt% modified polyamide (FR105 / CM4000 weight ratio 70/30 mixture, FR105: methoxymethylated nylon CM4000 manufactured by Toray Co., Ltd .: copolymerized polyamide manufactured by Toray Industries, Inc.) It applied using the wire bar, the coating film was dried, and the oriented film with a film thickness of 0.1 micrometer was formed. Next, the alignment film was rubbed to prepare a transparent resin substrate having the alignment film.

A cholesteric liquid crystal composition prepared by mixing each component at the blending ratio shown in Table 1 is applied to the surface having the alignment film of the transparent resin substrate having the alignment film prepared above using a # 10 wire bar. did. The coating film is subjected to an orientation treatment at 100 ° C. for 5 minutes, and the coating film is subjected to a process of irradiation with weak ultraviolet rays of 0.1 to 45 mJ / cm ² followed by a heating treatment at 100 ° C. for 1 minute. After repeating twice, the first cholesteric resin layer having a dry film thickness of 5 μm is formed by irradiating with an ultraviolet ray of 800 mJ / cm ^{2 in} a nitrogen atmosphere, and the base material, the alignment film and the cholesteric resin layer are formed in this order. Thus, a first circularly polarized light separating element was prepared.

(1-2: Preparation of retardation film)
A monomer composition composed of 97.8% by weight of methyl methacrylate and 2.2% by weight of methyl acrylate was polymerized by a bulk polymerization method to obtain resin pellets.

  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 allyl methacrylate, and the inner layer is composed of butyl acrylate and styrene as main components and a small amount of acrylic acid. It is a soft elastic copolymer obtained by crosslinking and copolymerizing allyl, 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 μm, and the particle size including the outer layer was 0.22 μm.

  70 parts by weight of the resin pellets and 30 parts by weight of the rubber particles were mixed and melt kneaded with a twin screw extruder to obtain a methacrylic acid ester polymer composition A (glass transition temperature 105 ° C.).

  By coextruding the methacrylic ester polymer composition A (b layer) and the styrene maleic anhydride copolymer (glass transition temperature 130 ° C.) (a layer) at a temperature of 280 ° C., a b layer / a layer A multilayer film having an average thickness of 45/70/45 (μm) with a three-layer structure of / b layers was obtained. The laminated film is stretched obliquely at a stretching temperature of 134 ° C. and a stretching ratio of 1.8 times so that the slow axis is in a direction inclined by 45 degrees with respect to the MD direction by a tenter stretching machine. Got.

  The retardation in the front direction of the optically anisotropic layer was 140 nm, and the retardation in the thickness direction was −85 nm (each numerical value is a measured value after stretching). Furthermore, both surfaces of this optically anisotropic layer were subjected to corona discharge treatment so that the wetting index was 56 dyne / cm. This optically anisotropic layer was used as a retardation film in the following.

(1-3: Preparation of polarizing plate)
A composite laminate in which a polarizing plate having a polarizer and a protective film was attached to a glass substrate was prepared.
A 75 μm-thick polyvinyl alcohol film was uniaxially stretched 2.5 times, immersed in an aqueous solution at 30 ° C. containing 0.2 g / L of iodine and 60 g / L of potassium iodide, and then 70 g / L of boric acid and It was immersed in an aqueous solution containing 30 g / L of potassium iodide and simultaneously uniaxially stretched 6.0 times and held for 5 minutes. Finally, it was dried at room temperature for 24 hours to obtain a polarizer having an average thickness of 30 μm and a polarization degree of 99.95%.
A polyvinyl alcohol adhesive is applied to both sides of the obtained polarizer, a cellulose triacetate protective film (manufactured by Fuji Photo Film Co., Ltd .; TF80UL) is bonded to one surface, and a glass substrate is bonded to the other surface to protect the film. A composite laminate of a polarizing plate and a substrate having a layer structure of: / polyvinyl alcohol-based adhesive layer / polarizer / polyvinyl alcohol-based adhesive layer / glass substrate was prepared.

(1-4: Adhesion of retardation film and circularly polarized light separating element: preparation of brightness enhancement film)
An acrylic pressure-sensitive adhesive (manufactured by Daido Kasei; E-5301) was applied to one side of the retardation film obtained in (1-2) above using an applicator so that the average thickness was 40 μm. This coated surface is aligned with the cholesteric resin layer surface of the first circularly polarized light separating element obtained in (1-1) above, and bonded at 80 ° C. with a nip pressure of 2 kgf / 50 mm using a laminator. A brightness enhancement film having a laminated structure of first circularly polarized light separating element / second adhesive layer / retardation film was obtained.

(1-5: Production of optical member)
The brightness enhancement film obtained in the above (1-4) was cut into a strip shape having a length of 20 cm and a width of 2.5 cm. On the surface of the retardation film side, an addition reaction type silicone pressure sensitive adhesive (trade name SD4560, manufactured by Toray Dow Corning) (hereinafter sometimes referred to as “silicone composition 1”) and a curing agent (SRX212). , Manufactured by Toray Dow Corning Co., Ltd.) was applied using an applicator. The coated surface and the polarizing plate obtained in (1-3) above and the polarizing plate side (protective film side) surface of the composite laminate of the substrate are combined and attached with a 2 kgf load roller, and the coating surface is 100 ° C. for 3 minutes. The optical member having a laminated structure of first circularly polarized light separating element / second adhesive layer / retardation film / first adhesive layer / polarizing plate / substrate was obtained. The thickness of the 1st adhesion layer after hardening was 25 micrometers. A plurality of optical member samples were prepared, and each sample was subjected to the following evaluation.

(1-6: Evaluation: Initial peeling force)
The following evaluation was performed after leaving for 24 hours at 25 degreeC and 60% of humidity after completion | finish of the manufacturing process of said (1-5). The results are shown in Table 1.
(A) The substrate and the polarizing plate are fixed, and the layers from the first circularly polarized light separating element to the retardation film in the band shape are separated from the polarizing plate by using a constant speed (300 mm / min) tensile tester. The film was peeled off at 0 °, and the force (N / inch) required for peeling in the first adhesive layer was measured. Further, the peeled surface after peeling was observed, and ◎ indicates that the first adhesive layer was completely peeled off without any adhesive residue on the polarizing plate surface, ○ indicates that adhesive residue was generated on the way, and ○ indicates that tear occurred. It was evaluated.
(B) The substrate, the polarizing plate and the retardation film are fixed, and the layer of the first circularly polarized light separating element having the band shape is removed from the retardation film by using a constant speed (300 mm / min) tensile tester. The film was peeled off at 0 ° and the force (N / inch) required for peeling off the second adhesive layer was measured.

(1-7: Evaluation: peel strength after aging)
After completion of the production process (1-5), the optical member was left in an oven at a temperature of 150 ° C. for 8 hours to perform an aging treatment. Thereafter, the sample was allowed to stand for 24 hours at a temperature of 25 ° C. and a humidity of 60%, and then the same evaluations as in (A) and (B) above were performed. The results are shown in Table 1.

(Example 2: Production of brightness enhancement film having one cholesteric resin layer, part 2)
The brightness enhancement film obtained in (1-4) of Example 1 was cut into a strip shape having a length of 20 cm and a width of 2.5 cm. On the surface of the retardation film side, a radical curable silicone adhesive (trade name SH4280, manufactured by Toray Dow Corning) (hereinafter sometimes referred to as “silicone composition 2”) and a catalyst (benzoyl) A mixture of peroxide (peroxide) at a ratio of 0.5 part by weight with respect to 100 parts by weight of the main agent was applied using an applicator, and the solvent in the adhesive was evaporated by preliminary drying. This coated surface and the polarizing plate side (protective film side) surface of the composite laminate obtained in (1-3) of Example 1 were combined and pasted with a 2 kgf load roller, and treated at 150 ° C. for 5 minutes. Thus, an optical member having a laminated structure of the first circularly polarized light separating element / second adhesive layer / retardation film / first adhesive layer / polarizing plate / substrate was obtained. The thickness of the 1st adhesion layer after hardening was 25 micrometers. A plurality of samples of the optical member were prepared, and each sample was subjected to the same evaluation as (1-6) and (1-7) of Example 1. The results are shown in Table 1.

(Example 3: Creation of a brightness enhancement film having two cholesteric resin layers)
(3-1: Preparation of first and second circularly polarized light separating elements)
Except having changed the compounding ratio of the cholesteric liquid crystal composition as described in each of “first layer” and “second layer” in Table 1, the same operation as in (1-1) of Example 1, A first circularly polarized light separating element and a second circularly polarized light separating element were prepared.

(3-2: Preparation of brightness enhancement film)
An acrylic pressure-sensitive adhesive (manufactured by Daido Kasei; E-5301) was applied to the cholesteric resin layer surface of the second circularly polarized light separating element obtained in (3-1) above using an applicator so that the average thickness was 40 μm. The coated surface and the substrate surface of the first circularly polarized light separating element obtained in (3-1) above are combined, and bonded using a laminator at 80 ° C. with a nip pressure of 2 kgf / 50 mm, A laminated body having a laminated structure of second circularly polarized light separating element / third adhesive layer / first circularly polarized light separating element was obtained.
An acrylic pressure-sensitive adhesive (manufactured by Daido Kasei; E-5301) was applied to one side of the retardation film obtained in (1-2) of Example 1 using an applicator so that the average thickness was 40 μm. The coated surface and the cholesteric resin layer (of the first circularly polarized light separating element) surface of the laminate obtained above were combined and a laminator was used at 80 ° C. with a nip pressure of 2 kgf / 50 mm. The brightness enhancement film having a laminated structure of the second circularly polarized light separating element / the third adhesive layer / the first circularly polarized light separating element / the second adhesive layer / the retardation film was obtained by bonding. The thicknesses of the second adhesive layer and the third adhesive layer after curing were 40 μm.

(3-3: Production of optical member)
The brightness enhancement film obtained in the above (3-2) was cut into a strip shape having a length of 20 cm and a width of 2.5 cm. Applying 0.8 parts by weight of the silicone composition 1 main ingredient and curing agent (SRX212, manufactured by Toray Dow Corning) to 100 parts by weight of the main ingredient on the surface of the retardation film side, is applied using an applicator. did. This coated surface and the polarizing plate side (protective film side) surface of the composite laminate obtained in (1-3) of Example 1 were combined and pasted with a 2 kgf load roller, and treated at 100 ° C. for 3 minutes. Optical member having a laminated structure of second circularly polarized light separating element / third adhesive layer / first circularly polarized light separating element / second adhesive layer / retardation film / first adhesive layer / polarizing plate / substrate Got. The thickness of the 1st adhesion layer after hardening was 25 micrometers. A plurality of optical member samples were prepared, and each sample was subjected to the following evaluation.

(3-4: Evaluation: Initial peeling force)
The following evaluation was performed after leaving for 24 hours at 25 degreeC and 60% of humidity after completion | finish of the manufacturing process of said (3-3). The results are shown in Table 1.
(A) A substrate and a polarizing plate are fixed, and a layer from the second circularly polarized light separating element to the retardation film in the band shape is a constant speed (300 mm / min) tensile tester according to JIS Z0237. The film was peeled off from the polarizing plate at 180 °, and the force (N / inch) required for peeling in the first adhesive layer was measured. Further, the peeled surface after peeling was observed, and ◎ indicates that the first adhesive layer was completely peeled off without any adhesive residue on the polarizing plate surface, ○ indicates that adhesive residue was generated on the way, and ○ indicates that tear occurred. It was evaluated.
(B) A substrate, a polarizing plate and a retardation film are fixed, and the layer from the second circularly polarized light separating element to the first circularly polarized light separating element in the band shape is compliant with JIS Z0237, at a constant speed (300 mm / Min) was used, and the force (N / inch) required for peeling in the second adhesive layer was measured.

(3-5: Evaluation: peel strength after aging)
After completion of the production process (1-5), the optical member was left in an oven at a temperature of 150 ° C. for 8 hours to perform an aging treatment. Thereafter, the sample was allowed to stand for 24 hours at a temperature of 25 ° C. and a humidity of 60%, and then the same evaluations as in (A) and (B) above were performed. The results are shown in Table 1.

(Comparative Example 1)
In the step (1-5), an optical member was produced in the same manner as in Example 1 except that an acrylic pressure-sensitive adhesive (manufactured by Daido Kasei; E-5301) was used instead of the silicone pressure-sensitive adhesive. And evaluated. The results are shown in Table 1.

The abbreviations in Table 1 and Table 2 indicate the following:
Compound (1); Compound A2
Compound (2) A; Δn = 0.18 Number of polymerizable groups in one molecule, average refractive index of 1.645
Compound (2) B; Δn = 0.20 Two polymerizable groups in one molecule, average refractive index 1.638
Photopolymerization initiator X: Irgacure 907 (Ciba Specialty Chemicals)

  As described above, in Examples 1 to 3 that satisfy the requirements of the present invention, as compared with Comparative Example 1, favorable peeling favorable for product recycling was possible.

It is sectional drawing which shows one specific example of the optical member of this invention. It is sectional drawing which shows another specific example of the optical member of this invention. It is sectional drawing which shows the example of the aspect of peeling of the lamination | stacking of the optical member of this invention. It is sectional drawing which shows the example of the aspect of peeling of the lamination | stacking of the optical member of a prior art.

Explanation of symbols

100, 200 Optical member 101 Substrate 111 Polarizing plate 121 First adhesive layer 122 Second adhesive layer 131 Retardation film 132 (first) circularly polarized light separating element 133 Second circularly polarized light separating element

Claims (6)

In an optical member having a polarizing plate, a first adhesive layer, a retardation film, a second adhesive layer, and a circularly polarized light separating element,
Initial peel force P ₁₁ at 25 ° C. and peel force Q ₁₁ at 25 ° C. after aging for 8 hours at the interface between the polarizing plate and the first adhesive layer, from the retardation film to the circularly polarized light separating element Between the initial peel force PX at 25 ° C. and the peel force QX at 25 ° C. after aging at 150 ° C. for 8 hours from the retardation film to the circularly polarized light separating element, the following formula (1):
(PX-P ₁₁ ) <(QX-Q ₁₁ ) (1)
And the first adhesive layer is a cured product of a silicone-based composition. The following formulas (2) and (3):
P ₁₁ <PX (2)
Q ₁₁ <QX (3)
The optical member according to claim 1, wherein The optical member according to claim 1, wherein P ₁₁ is 0.1 to 5 N / inch.   The optical member according to any one of claims 1 to 3, wherein the cured product of the silicone composition is obtained by curing the silicone composition by an addition reaction.   The optical member according to claim 1, wherein the circularly polarized light separating element is formed by laminating a base material, an alignment film, and a resin layer having cholesteric regularity in this order.   The optical member of any one of Claims 1-5, and the liquid crystal display device which has a liquid crystal panel in the surface at the side of the said polarizing plate.

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