JPWO2015076411A1 - Display device - Google Patents

Abstract

An object of the present invention is to provide a display device in which the panel bend is reduced, and thereby the overlap width between the bezel and the panel can be reduced. The display device according to the present invention includes a display panel (11) and a casing (15A, 15B) that includes the display panel (11) and a bezel (15B) that covers the peripheral edge of the surface of the display panel (11). ), And the display panel (11) is not fixed to the casing (15A, 15B) via an adhesive, and the display panel (11) has an edge side surface. Includes a display element and a polarizing plate disposed on at least one surface of the display element, and the polarizing plate includes a polarizer and an optical film disposed on the polarizer, and the optical film The ratio CHE / CTE between the hygroscopic expansion coefficient CHE in the direction X parallel to the absorption axis of the polarizer and the thermal expansion coefficient CTE in the direction X is 0.7 or less, and the 40 ° C. and 20% RH environment Tensile modulus in direction X is 2 Is GPa.

Description

  The present invention relates to a display device.

  Display devices such as liquid crystal display devices, organic EL display devices, and electrophoretic display devices are required to be thin.

  For example, the liquid crystal display device includes a display panel and a housing that accommodates the display panel. The display panel includes a liquid crystal cell and a pair of polarizing plates that sandwich the liquid crystal cell. The housing includes a bezel (frame member) that covers the peripheral edge of the display surface of the display panel, and a back member that covers the non-display surface of the display panel. And the display panel is being fixed to the housing | casing through the adhesive agent etc. (for example, refer patent document 1 and 2).

JP 2013-8016 A Japanese Patent No. 3799004

  By the way, in the liquid crystal display device immediately after assembly, when the backlight is turned on for a certain period of time, the display panel is likely to be warped (panel bend). Panel bends are likely to occur such that the backlight side surface is convex and the display side surface is concave. When such a panel bend occurs, if the overlap width H between the bezel of the housing and the display panel is reduced, the end portion of the display panel cannot be suppressed by the bezel and easily protrudes outside the housing (see FIG. 3A). As a result, it has been found that there is a problem that the display panel cannot be stably held in the housing. In particular, the problem is remarkable when the edge side surface of the display panel is not fixed to the housing with an adhesive or the like.

  The panel bend is considered to be generated when a polarizer containing water in manufacturing or transporting a display panel is heated by a backlight to dehydrate and contract. Therefore, the present inventors have found that the panel bend can be reduced by expanding the optical film adjacent to the polarizer so as to counteract the contraction of the polarizer. Then, by reducing the panel bend, it was found that even if the overlap width H of the panel and the bezel is reduced, the end of the panel can be prevented from coming out of the housing and can be stably held in the housing (see FIG. 3B).

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a display device in which the panel bend is reduced, and thereby the overlap width between the bezel and the display panel can be reduced.

[1] A display device that includes a display panel and a housing that houses the display panel and has a bezel that covers a peripheral portion of the display surface of the display panel, the edge side surface of the display panel being an adhesive The display panel includes a display element and a polarizing plate disposed on at least one surface of the display element, and the polarizing plate includes a polarizer, A ratio CHE / CTE of the hygroscopic expansion coefficient CHE in the direction X parallel to the absorption axis of the polarizer of the optical film and the thermal expansion coefficient CTE in the direction X is 0. The display device has a tensile modulus of elasticity in the direction X of 2 to 6 GPa in an environment of 40 ° C. and 20% RH.
[2] The display device according to [1], wherein a minimum value of an overlap width H between the bezel and the display panel is 0.3 to 5.0% with respect to a length of a major axis of the display panel. .
[3] The display device according to [1] or [2], wherein the polarizer has a thickness of 5 to 26 μm.
[4] The display device according to any one of [1] to [3], wherein the display element is a liquid crystal cell.
[5] The liquid crystal cell includes a liquid crystal layer and a pair of glass substrates that sandwich the liquid crystal layer. The thickness of the glass substrate is t (mm), and the length of the long axis of the display panel is l (mm). ), The display device according to [4], wherein t / l is 0.0002 to 0.0005.
[6] The display device according to [5], wherein the glass substrate has a thermal expansion coefficient CTE of 30 × 10 ⁻⁷ to 50 × 10 ⁻⁷ cm / cm / ° C.
[7] The display panel further includes a backlight, and the display panel is disposed on the liquid crystal cell, a first polarizing plate disposed on a display surface of the liquid crystal cell, and a surface on the backlight side of the liquid crystal cell. A first polarizing plate, a protective film F1 disposed on a display-side surface of the first polarizer, and the first polarizer. A protective film F2 disposed on the surface of the liquid crystal cell, and the second polarizing plate is disposed on the surface of the second polarizer and the liquid crystal cell side of the second polarizer. Any of [2] to [6], including a protective film F3 and a protective film F4 disposed on the backlight side surface of the second polarizer, wherein at least the protective film F1 is the optical film. A display device according to any one of the above.
[8] The display device according to [7], wherein the direction X of the protective film F1 and the absorption axis direction of the first polarizer coincide.
[9] The display device according to [7] or [8], wherein a long axis of the display panel and an absorption axis of the first polarizer are parallel to each other.

  ADVANTAGE OF THE INVENTION According to this invention, a panel bend can be reduced and the display apparatus which can make the overlap width of a bezel and a display panel small by it can be provided.

It is a disassembled perspective view which shows the structure of the display apparatus of 1st embodiment. It is a fragmentary sectional view which shows the AA line cross section of FIG. It is a schematic diagram which shows the mode of the curvature of the conventional display panel. It is a schematic diagram which shows the mode of the curvature of the display panel in this invention. It is a schematic diagram which shows an example of a structure of a display panel. It is a schematic diagram which shows the other example of a structure of a display panel. It is a fragmentary sectional view which shows the cross section of the display apparatus of 2nd embodiment.

  The display device of the present invention includes a display panel and a housing that houses the display panel. The display device can be a liquid crystal display device, an organic EL display device, an electrophoretic display device, or the like.

(First embodiment)
FIG. 1 is an exploded perspective view showing the configuration of the display device of the first embodiment. FIG. 2 is a partial cross-sectional view showing a cross section taken along line AA of FIG. As shown in FIG. 1, the display device 10 includes a display panel 11, a backlight unit 13, and a housing 15 that houses them.

  The housing 15 includes a back member 15 </ b> A that covers the back and side surfaces of the display panel 11, and a frame-like bezel 15 </ b> B that covers the peripheral edge of the display surface of the display panel 11. The housing 15 may have a substantially rectangular parallelepiped shape as a whole.

  The material of the back member 15A and the bezel 15B can be, for example, a metal having high thermal conductivity such as aluminum (Al) or iron (Fe); polycarbonate (PC), a resin obtained by adding an ABS resin to polycarbonate, or the like.

  It is preferable that the edge side surface of the display panel 11 is not fixed to the housing 15 with an adhesive or the like. This is because the stress generated by pressing the warp of the display panel 11 is easily released. Further, a spacer 17 or a poron 19 may be disposed between the display panel 11 and the housing 15 in order to make it easier to hold the display panel 11 in the housing 15 (see FIG. 2).

  In the present invention, as described later, warping of the display panel 11 when heated by the backlight is reduced. Thereby, the overlapping width H of the display panel 11 and the bezel 15B can be made smaller than the conventional one (see FIG. 2).

  That is, when the warp of the display panel 11 is large, the end of the display panel 11 cannot be suppressed by the bezel 15B of the housing 15 and easily protrudes outside the housing 15 (see FIG. 3A). In order to stably hold such a display panel 11 in the housing 15, it is necessary to increase the overlapping width H of the display panel 11 and the bezel 15B.

  On the other hand, in this embodiment, as will be described later, the warpage of the display panel 11 is reduced. Thereby, even if the overlapping width H of the display panel 11 and the bezel 15B is reduced, the end of the display panel 11 does not protrude from the casing 15 and can be stably held in the casing 15 (see FIG. 3B). ).

  The overlap width H between the display panel 11 and the bezel 15B may or may not be uniform throughout the display device 10. In the present invention, the display panel 11 and the bezel can be secured in order to stably hold the display panel 11 in the casing 15 without taking up a large display area and fixing the display panel 11 to the casing 15 with an adhesive or the like. It is preferable to make the minimum value of the overlap width H with 15B as small as possible.

  Although the minimum value of the overlap width H of the display panel 11 and the bezel 15B depends on the size of the display panel 11, it is preferably 5 to 20 mm, and more preferably 5 to 15 mm. The minimum value of the overlap width H of the display panel 11 and the bezel 15B is preferably 0.3 to 5.0% with respect to the long axis of the display panel 11, and preferably 0.3 to 3.0%. More preferred. The long axis of the display panel 11 indicates, for example, the long side of the display panel 11 when the display panel 11 is rectangular; and the long axis of the display panel 11 when it is elliptical.

  The maximum value of the overlap width H between the display panel 11 and the bezel 15B is preferably 40 mm or less in order to increase the display area. The maximum value of the overlapping width H of the display panel 11 and the bezel 15B can be 10% or less, preferably 7.5% or less with respect to the long axis of the display panel 11.

  The warp of the display panel 11 is adjusted by the physical properties (CHE / CTE, tensile elastic modulus) of the optical film, the thickness of the polarizer, the CTE of the transparent substrate included in the display element, etc., as will be described later; preferably the optical film The physical properties (CHE / CTE, tensile elastic modulus) can be adjusted.

<Display panel 11>
The display panel 11 includes at least a display element and a polarizing plate disposed on the display surface. The display element can be a liquid crystal cell (see FIG. 4), an organic EL element (see FIG. 5), or the like. The polarizing plate includes a polarizer and an optical film.

<Polarizer>
A polarizer is an element that passes only light having a plane of polarization in a certain direction, and a typical polarizer known at present is a polyvinyl alcohol polarizing film. The polyvinyl alcohol polarizing film includes those obtained by dyeing iodine on a polyvinyl alcohol film and those obtained by dyeing a dichroic dye.

  The polyvinyl alcohol polarizing film may be a film (preferably a film further subjected to durability treatment with a boron compound) dyed with iodine or a dichroic dye after uniaxially stretching the polyvinyl alcohol film; A film obtained by dying an alcohol film with iodine or a dichroic dye and then uniaxially stretching (preferably a film further subjected to a durability treatment with a boron compound) may be used.

  The polarizer has an absorption axis that is the maximum stretching axis. The absorption axis direction of the polarizer can be confirmed as a direction that becomes transparent when the polarizer is overlapped with a polarizer having a known absorption axis. The absorption axis direction of the polarizer is preferably coincident with the MD direction of the polarizer. The MD direction refers to the longitudinal direction of the polarizer (film) in the wound body of the long polarizer (film).

  The thickness of the polarizer is preferably 2 to 30 μm, and more preferably 5 to 26 μm in order to reduce the contraction force of the polarizer.

<Optical film>
The optical film can be disposed on the polarizer directly or through other layers. The optical film may be disposed on the surface on the display element side of the polarizer or on the surface on the opposite side, and preferably on the surface on the opposite side to the display element.

  As described above, it is considered that the panel bend is caused by contraction of the polarizer by receiving the heat of the backlight from the polarizer containing water at the time of manufacturing or transporting the panel and removing water. On the other hand, the present inventors have found that the panel bend can be suppressed by expanding the optical film so as to counteract the contraction of the polarizer when receiving the heat of the backlight.

  Specifically, an optical film that has received heat from the backlight tends to simultaneously expand due to heat and shrink due to the removal of water. By making the “expansion force due to heat” in the optical film relatively larger than the “shrinkage force due to the removal of water”; that is, by making CHE / CTE below a certain value, the optical film as a whole can be easily expanded. I found out.

  In order to increase the “thermal expansion force” of the optical film, it is preferable that the tensile elastic modulus of the optical film under heating is set to a certain level or more. This is because the thermal expansion force of the optical film is proportional to the product of the tensile elastic modulus, thickness, and dimensional change of the optical film.

  That is, since the contraction of the polarizer is maximized in the absorption axis direction of the polarizer, the thermal expansion coefficient of the optical film in the direction X parallel to the absorption axis of the polarizer is CTE (unit: ppm / ° C.). When the hygroscopic expansion coefficient of X is CHE (unit: ppm /%), the ratio CHE / CTE is preferably not more than a certain value, specifically preferably not more than 0.7. It is more preferably 6 or less, and further preferably 0.5 or less.

  The direction X parallel to the absorption axis of the polarizer may be preferably 5 ° or less, more preferably 1 ° or less, and still more preferably 0 ° with respect to the absorption axis direction of the polarizer. As will be described later, this is because the expansion force of the optical film is easily countered with the contraction force of the polarizer.

  The “direction X parallel to the absorption axis of the polarizer” of the optical film is preferably the longitudinal direction (MD direction) of the optical film. This is because when the polarizer and the optical film are bonded together by roll-to-roll to produce a polarizing plate, the MD direction (absorption axis direction) of the polarizer matches the MD direction of the optical film. A longitudinal direction (MD direction) means a longitudinal direction in a wound body of a long optical film. The longitudinal direction (MD direction) of the optical film may be either one of the in-plane slow axis direction of the optical film and the direction orthogonal thereto.

  The tensile modulus at 40 ° C. in the direction X of the optical film is preferably 2 GPa or more. When the tensile elastic modulus at 40 ° C. is above a certain level, the expansion force of the optical film due to heat can be easily increased. On the other hand, since the shrinkage applied to the polarizer cannot be released if the tensile modulus is too large, the tensile modulus at 40 ° C. is preferably 6 GPa or less.

  The CHE / CTE of the optical film is preferably 0.7 or less and the tensile modulus at 40 ° C. is preferably 2 GPa or more and 6 GPa or less.

  The CHE / CTE of the optical film can be adjusted depending on the type and composition of the resin (for example, the content ratio of two or more resins), stretching conditions, and the like. The tensile elastic modulus at 40 ° C. of the optical film can be adjusted by the type, molecular weight and composition (for example, the content ratio of two or more resins) of the resin, stretching conditions, and the like.

  Examples of resins with CHE / CTE and tensile modulus satisfying the above range include (meth) acrylic resin, polycarbonate resin, polyester resin, polyvinyl chloride resin, styrene resin (styrene maleic anhydride copolymer, styrene Examples include acrylonitrile copolymer, SPS (syndiotactic polystyrene), and cycloolefin resin.

  The (meth) acrylic resin can be a homopolymer of (meth) acrylic acid ester; or a copolymer of (meth) acrylic acid ester and another monomer copolymerizable therewith.

  The (meth) acrylic acid ester is preferably a (meth) acrylic acid alkyl ester, and more preferably methyl methacrylate.

  Examples of other monomers copolymerizable with methyl methacrylate include: alkyl methacrylates having 2 to 18 carbon atoms in the alkyl moiety; alkyl alkyl esters having 1 to 18 carbon atoms in the alkyl moiety; acrylic acid Α, β-unsaturated acids such as methacrylic acid; unsaturated group-containing dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid; aromatic vinyl compounds such as styrene, α-methylstyrene and nucleus-substituted styrene; acrylonitrile And α, β-unsaturated nitriles such as methacrylonitrile; acid anhydrides such as maleic anhydride and glutaric anhydride; maleimides, N-substituted maleimides, etc., preferably aromatic vinyl compounds such as styrene, anhydrous It may be an acid anhydride such as maleic acid. These other monomers may be used alone or in combination of two or more.

  Preferred examples of the copolymer include methacrylic acid alkyl ester / aromatic vinyl compound / acid anhydride copolymer, methacrylic acid alkyl ester / acid anhydride copolymer, methacrylic acid alkyl ester / styrene copolymer, and the like. included.

  The content ratio of the structural unit derived from the alkyl methacrylate (preferably methyl methacrylate) with respect to all the structural units constituting the copolymer is preferably 30 mol% or more, and preferably 50 mol% or more. More preferred.

  The polycarbonate may be a polymer having a carbonate bond (—O—CO—O—) in the main chain. Examples of the polycarbonate film include Pure Ace, Pure Ace WR (manufactured by Teijin Chemicals Ltd.), Elmec (manufactured by Kaneka Corp.), and the like.

  Examples of the polyester include polyethylene terephthalate and polyethylene naphthalate.

  The cycloolefin resin may be a polyolefin having an alicyclic structure in the main chain. Examples of the alicyclic structure include a saturated alicyclic hydrocarbon (cycloalkane) structure, an unsaturated alicyclic hydrocarbon (cycloalkene) structure, and the like. Of these, a cycloalkane structure is preferable from the viewpoint of good mechanical strength, heat resistance, and the like.

  The carbon atom number which comprises an alicyclic structure is about 4-30 normally, Preferably it is 5-20, More preferably, it is 5-15. The ratio of the repeating unit containing an alicyclic structure in the cycloolefin resin is preferably 55% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more.

  The cycloolefin resin is preferably a norbornene-based resin because of its good transparency and moldability. The norbornene-based resin may be a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof; It may be an addition polymer or an addition copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof.

  Examples of the monomer having a norbornene structure include bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.12,5] deca-3,7-diene ( Common name: dicyclopentadiene), 7,8-benzotricyclo [4.3.0.12,5] dec-3-ene (common name: methanotetrahydrofluorene), tetracyclo [4.4.0.12, 5.17,10] dodec-3-ene (common name: tetracyclododecene) and the like. The ring contained in these compounds may further have a substituent. Examples of the substituent include an alkyl group, an alkylene group, and a polar group. One type of monomer having a norbornene structure may be used, or two or more types may be combined.

  Examples of other monomers capable of ring-opening copolymerization with a monomer having a norbornene structure include monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene; and cyclic conjugated dienes such as cyclohexadiene and cycloheptadiene.

  Examples of other monomers that can be addition copolymerized with a monomer having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene; cycloolefins such as cyclobutene, cyclopentene, and cyclohexene; Non-conjugated dienes such as 4-hexadiene, 4-methyl-1,4-hexadiene and 5-methyl-1,4-hexadiene are included, preferably α-olefins, and more preferably ethylene. One kind of these monomers may be used, or two or more kinds may be combined.

  Among norbornene-based resins, as a repeating unit, a bicyclo [3.3.0] octane-2,4-diyl-ethylene structure and a tricyclo [4.3.0.12.5] decane-7,9-diyl- It preferably contains an ethylene structure. A film containing such a resin can have a relatively small dimensional change and stable optical properties.

  The resin in which the CHE / CTE and the tensile elastic modulus satisfy the above ranges may be a mixture of two or more kinds of resins. For example, a mixture of a resin (A) having a tensile modulus at 40 ° C. of 2 GPa or more and a CHE / CTE of 0.6 or more; and a resin (B) having a CHE / CTE of less than 0.6 There may be.

(Resin (A))
The resin (A) can function not only as the main polymer of the optical film, but also has a function of increasing the tensile elastic modulus under heating.

  The tensile elastic modulus of the resin (A) in a 40 ° C., 20% RH environment is preferably 2 GPa or more, and more preferably 3 GPa or more in order to increase the expansion force under heating. On the other hand, since the shrinkage applied to the polarizer cannot be released if the tensile elastic modulus is too large, the tensile elastic modulus of the resin (A) in a 40 ° C., 20% RH environment is preferably 6 GPa or less, preferably 5 GPa or less. More preferably.

  The tensile elastic modulus of the resin (A) under a 40 ° C. and 20% RH environment can be measured by the following method. That is, a 40 μm-thick film made of the resin (A) is produced and cut into a size of 100 mm (MD direction) × 10 mm (TD direction) to obtain a test piece. Based on JIS K7127, this test piece is pulled in MD direction using Tensilon RTC-1225A manufactured by Orientec Co., Ltd., and the tensile elastic modulus is measured. The measurement is performed at 40 ° C. and 20% RH. The MD direction indicates the longitudinal direction of the film in the long roll of the film; the TD direction indicates the width direction of the film.

  The CHE / CTE of the resin (A) is preferably 0.6 or more, more preferably 0.8 or more, further preferably 1.0 or more, and 1.2 or more. Particularly preferred. The upper limit of the CHE / CTE of the resin (A) can be about 2.0, preferably about 1.5.

The CHE / CTE of the resin (A) can be obtained, for example, by the following procedure.
1) A 40 μm-thick film made of resin (A) is formed, cut into a predetermined size, and used as a test piece. The film is preferably formed by a solution casting film forming method. And CTE of the said test piece is measured by TMA method based on ASTM E-831 or JIS K7197, and CTE (unit: ppm / degreeC) of resin (A) is obtained.
2) In the same manner as described above, a test piece made of resin (A) having a thickness of 40 μm was prepared; the dimension in the MD direction after being stored for 24 hours in an environment of 23 ° C. and 20% RH, and a temperature of 23 ° C. and 80% RH The dimension in the MD direction after storage for 24 hours under the environment is measured. The obtained measured value is applied to the following formula to obtain CHE (unit: ppm /% RH) of the resin (A) (see the following formula).
CHE (ppm /% RH) = {(MD direction dimension of specimen after storage at 23 ° C. and 80% RH−MD direction dimension of specimen after storage at 23 ° C. and 20% RH) / 23 ° C. and 20% RH Dimension of test specimen in MD direction after storage} / (80% RH-20% RH)
The MD direction represents the long direction of the film in the long film roll; the TD direction represents the width direction of the film.
3) The CHE / CTE of the resin (A) is calculated from the CTE and CHE of the resin (A) obtained in 1) and 2) above.

  Examples of the resin (A) in which the tensile elastic modulus at 40 ° C. and CHE / CTE satisfy the above ranges include cellulose ester and the above-mentioned (meth) acrylic resin, and cellulose ester is preferable.

Cellulose ester Cellulose ester is a compound obtained by esterifying cellulose and at least one of aliphatic carboxylic acid and aromatic carboxylic acid. That is, the cellulose ester contains at least one of an aliphatic acyl group and an aromatic acyl group, and preferably contains an aliphatic acyl group.

  The number of carbon atoms in the aliphatic acyl group is preferably 2 to 7, and more preferably 2 to 4. Examples of the aliphatic acyl group include acetyl group, propionyl group, butanoyl group and the like.

  Specific examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, cellulose acetate butyrate and the like, and cellulose acetate and cellulose acetate propionate are preferable because they have appropriate hydrophobicity.

  The total substitution degree of the acyl group of the cellulose ester is 2.0 or more, preferably 2.5 or more, more preferably 2.6 or more, and further preferably 2.8 or more. By increasing the total substitution degree of the acyl group, it is possible to make it difficult to express the retardation of the film. The upper limit of the total substitution degree of the acyl group can be, for example, 3.0, preferably 2.99.

  The acyl group of the cellulose ester preferably contains an acetyl group. The acyl group of the cellulose ester may further contain an acyl group having 3 or more carbon atoms, and the degree of substitution may be 2.7 or less.

  The substitution degree of the acyl group of cellulose ester can be measured by the method prescribed in ASTM-D817-96.

  The glass transition temperature Ta of the resin (A) preferably satisfies the expressions (1) to (3) described later. For example, the glass transition temperature Ta of the resin (A) can be 105 to 180 ° C.

  The glass transition temperature Ta of the resin (A) is a method in accordance with JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 type manufactured by Perkin Elmer) as a midpoint glass transition temperature (Tmg). Can be measured. The heating rate can be 20 ° C./min.

(Resin (B))
The resin (B) has a function of making the optical film easily stretched (or easily expanded) under heating. Accordingly, the CHE / CTE of the resin (B) is preferably relatively low, preferably less than 0.6, more preferably 0.5 or less, and further preferably 0.4 or less. . The lower limit of the CHE / CTE of the resin (B) can be about 0 or about 0.05. The CHE / CTE of the resin (B) can be measured in the same manner as the CHE / CTE of the resin (A) described above.

  The tensile elastic modulus of the resin (B) under a 40 ° C. and 20% RH environment may be such that the tensile elastic modulus of the obtained optical film falls within the above range. Specifically, the tensile elastic modulus of the resin (B) in a 40 ° C., 20% RH environment can be 6 GPa or less, preferably 4.5 GPa or less. The tensile elastic modulus of the resin (B) under a 40 ° C. and 20% RH environment can be measured in the same manner as the tensile elastic modulus of the resin (A) under a 40 ° C. and 20% RH environment.

The glass transition temperature Tb of the resin (B) is preferably lower than the glass transition temperature Ta of the resin (A) in order to make the optical film easily stretched under heating. Specifically, it is preferable to satisfy the following formula (2).
Formula (2) Ta ≧ Tb + 80

  Tb is preferably lower than Ta by 100 ° C. or more. Tb can be, for example, in the range of −50 ° C. to 70 ° C.

  The glass transition temperature Tb of the resin (B) can be measured by the same method as the glass transition temperature Ta of the resin (A).

  Examples of the resin (B) satisfying the above CHE / CTE range include vinyl acetate resin, polylactic acid, polyacetal, polyurethane, and rubber particles.

  The vinyl acetate-based resin is a polymer containing a repeating unit derived from vinyl acetate, and examples thereof include polyvinyl acetate (a homopolymer of vinyl acetate) and an ethylene-vinyl acetate copolymer.

  Polyurethane is a resin obtained by reacting polyol and polyisocyanate. Examples of polyols include alkylene diols, polyester polyols, polyether polyols, and the like, preferably alkylene diols and polyester polyols. Examples of the polyisocyanate include alkylene diisocyanate and arylene diisocyanate, and alkylene diisocyanate is preferable. Preferable examples of the polyurethane include a polymer of alkylene diisocyanate and alkylene diol.

  The rubber particles are preferably fine particles having a core-shell structure, and examples thereof include acrylic fine particles; and styrene-butadiene copolymer fine particles.

  Examples of acrylic fine particles having a core-shell structure are a mixture of 80 to 98.9% by weight of methyl methacrylate, 1 to 20% by weight of alkyl acrylate, and 0.01 to 0.3% by weight of a polyfunctional grafting agent. A mixture of 75-98.5% by mass of an alkyl acrylate, 0.01-5% by mass of a polyfunctional crosslinking agent, and 0.5-5% by mass of a polyfunctional grafting agent. It is preferable to have an outermost hard layer obtained by polymerizing a mixture of 80 to 99% by mass of methyl methacrylate and 1 to 20% by mass of alkyl acrylate.

  Examples of fine particles of a styrene-butadiene copolymer having a core-shell structure include: a core portion made of a soft polymer; and a shell portion covering the periphery of the core portion made of another polymer. Includes fine particles.

  A soft polymer contains the structural unit derived from a conjugated diene monomer, and the structural unit derived from another monomer as needed. Examples of conjugated diene monomers include 1,3-butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, myrcene, etc. Of these, butadiene and isoprene are preferred. Examples of other monomers include styrene components such as styrene and α-methylstyrene. The content ratio of the structural unit derived from the conjugated diene monomer in the soft polymer is usually 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more.

  Examples of other polymers include a copolymer of acrylonitrile and styrene, a polymer mainly composed of a methacrylic ester such as methyl methacrylate, and the like.

  The volume average particle diameter of the elastic organic fine particles is 0.350 μm or less, preferably 0.010 to 0.350 μm, and more preferably 0.050 to 0.300 μm. If the particle size is above a certain value, the film can be easily stretched under heating; if the particle size is below a certain value, it is difficult to impair the transparency of the resulting film.

  The content ratio of the resin (A) and the resin (B) is preferably (A) :( B) = 10: 90 to 95: 5 (mass ratio), and (A) :( B) = 30: 70. -90: 10 (mass ratio) is more preferable, and (A) :( B) = 50: 50 to 90:10 (mass ratio) is more preferable. By setting the content ratio of the resin (B) to a certain value or more, the optical film can be easily stretched (easily expanded) under heating. By setting the content ratio of the resin (B) to a certain value or less, it is easy to maintain a high tensile elastic modulus while heating the optical film.

  The weight average molecular weight of the resin contained in the optical film is preferably 90,000 or more, and more preferably 150,000 or more, in order to easily increase the tensile modulus of the film under heating. The weight average molecular weight of the resin is preferably 1,000,000 or less, and more preferably 500,000 or less because it does not impair the moldability to the film.

The weight average molecular weight of the resin can be measured by gel permeation chromatography (GPC). The measurement conditions are as follows.
Solvent: Methylene chloride Column: Three Shodex K806, K805, K803G (manufactured by Showa Denko KK) are connected and used.
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 1.0 × 10 ^{6 to} 5.0 × 10 ² 13 calibration curves are used. The 13 samples are preferably selected so that the molecular weights are approximately equidistant.

  The optical film of the present invention may further contain various additives such as a peeling aid, an ultraviolet absorber, fine particles (matting agent) for imparting slipperiness, and a plasticizer as necessary.

(Peeling aid)
Since a part of the peeling aid or antistatic agent easily aggregates on the surface of the film-like material on the metal support side, the peelability of the film-like material from the metal support can be improved. The peeling aid or antistatic agent can be an organic or inorganic acidic compound, a surfactant, a chelating agent, and the like.

  Examples of the acidic compound include organic acids, partial alcohol esters of polyvalent carboxylic acids (for example, oxalic acid and citric acid), and the like. Specific examples of the partial alcohol ester of polyvalent carboxylic acid include the compounds described in paragraph (0049) of JP-A-2006-45497.

  Examples of surfactants include phosphate ester surfactants, carboxylic acid or carboxylate surfactants, sulfonic acid or sulfonate surfactants, sulfate ester surfactants, etc. It is. Examples of the phosphoric ester surfactant include the compounds described in paragraph (0050) of JP-A-2006-45497.

  The chelating agent is a compound capable of coordinating (chelating) a metal ion such as an iron ion or an alkaline earth metal ion such as calcium ion. Examples of the chelating agent include Japanese Patent Publication No. 6-8156, Including compounds described in JP-A-11-190892, JP-A-2000-18038, JP-A-2010-158640, JP-A-2006-328203, JP-A-2005-68246, JP-A-2006-306969 It is.

  Examples of commercially available peeling aids or antistatic agents include Hostastat HS-1, manufactured by Clariant Japan Co., Ltd., Elecut S-412-2, Elecut S-418, manufactured by Takemoto Yushi Co., Ltd., and Kao Co., Ltd. Neoperex G65 and the like are included.

  The content of the peeling aid or antistatic agent is preferably 0.005 to 1% by mass, more preferably 0.05 to 0.5% by mass, based on the total amount of the resin.

(UV absorber)
The ultraviolet absorber may be a benzotriazole compound, a 2-hydroxybenzophenone compound, a salicylic acid phenyl ester compound, or the like. Specifically, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- Triazoles such as (3,5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4 -Benzophenones such as methoxybenzophenone.

  The UV absorber may be a commercially available product. Examples thereof include Tinuvin 109, Tinuvin 171, Tinuvin 234, Tinuvin 326, Tinuvin 327, Tinuvin 328, and Tinuvin 928 manufactured by BASF Japan, or 2, 2'-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (molecular weight 659; examples of commercially available products are manufactured by ADEKA Corporation LA31) and the like.

  The content of the ultraviolet light inhibitor is preferably 1 ppm to 1000 ppm, more preferably 10 to 1000 ppm in terms of mass ratio with respect to the optical film.

(Matting agent)
The matting agent can impart slipperiness to the polarizing plate protective film. The matting agent may be fine particles made of an inorganic compound or an organic compound having heat resistance in the film forming process without impairing the transparency of the resulting film.

  Examples of inorganic compounds constituting the matting agent include silicon dioxide (silica), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, and hydrated calcium silicate. , Aluminum silicate, magnesium silicate and calcium phosphate. Of these, silicon dioxide and zirconium oxide are preferable, and silicon dioxide is more preferable in order to reduce an increase in haze of the obtained film.

  Specific examples of silicon dioxide include Aerosil 200V, Aerosil R972V, Aerosil R972, R974, R812, 200, 300, R202, OX50, TT600, NAX50 (above, Nippon Aerosil Co., Ltd.), Sea Hoster KEP-10, Sea Hoster KEP -30, Seahoster KEP-50 (manufactured by Nippon Shokubai Co., Ltd.), Silo Hovic 100 (manufactured by Fuji Silysia), nip seal E220A (manufactured by Nippon Silica Industry), Admafine SO (manufactured by Admatechs) and the like.

  The particle shape of the matting agent is indefinite, needle-like, flat or spherical, and may be preferably spherical, for example, because the transparency of the resulting film is easily improved.

  When the size of the matting agent particles is close to the wavelength of visible light, the light is scattered and the transparency is lowered. Therefore, the size of the particles of the matting agent is preferably smaller than the wavelength of visible light. / 2 or less is preferable. However, if the size of the particles is too small, the effect of improving slipperiness may not be exhibited, so the size of the particles is preferably in the range of 80 to 180 nm.

  The particle size means the size of an aggregate when the particle is an aggregate of primary particles. When the particles are not spherical, the size of the particles means the diameter of a circle corresponding to the projected area.

  The content of the matting agent can be about 0.05 to 1.0% by mass, preferably 0.1 to 0.8% by mass with respect to the total amount of the resin.

(Physical properties of optical film)
(Thickness)
When used as a polarizing plate protective film, the thickness of the optical film is preferably 10 to 60 μm and more preferably 20 to 40 μm in order to reduce the thickness of the polarizing plate.

(CHE / CTE)
The ratio CHE / CTE of the hygroscopic expansion coefficient CHE (unit: ppm /% RH) in the direction X parallel to the absorption axis of the polarizer and the thermal expansion coefficient CTE (unit: ppm / ° C.) in the direction X of the optical film is: As described above, in order to make the “expansion force due to heat” relatively larger than the “shrinkage force due to water removal” under heating, it is preferably 0.7 or less, and is 0.6 or less. It is preferably 0.5 or less. CHE / CTE can be 0 or more.

The CHE / CTE of the optical film can be obtained by the following procedure, as described above.
1) Cut an optical film into a predetermined size to obtain a test piece. CTE (unit: ppm / ° C.) in the direction X (preferably MD direction) parallel to the absorption axis of the in-plane polarizer is measured by the TMA method according to ASTM E-831 or JIS K7197. To do.
2) An optical film test piece was prepared in the same manner as in 1) above, and the dimension in direction X (preferably MD direction) after storage for a certain time (24 hours) at 23 ° C. and 20% RH, and 23 ° C. and 80%. The dimensions in direction X (preferably MD direction) after storage for a certain time (24 hours) under RH are measured. The obtained measured value is applied to the following formula to obtain CHE (unit: ppm /% RH) in the direction X (preferably MD direction) of the optical film (see the following formula).
CHE (ppm /% RH) = {(dimension in direction X of specimen after storage at 23 ° C. and 80% RH−dimension in direction X of specimen after storage at 23 ° C. and 20% RH) / 23 ° C. 20 Dimension of specimen X in direction X after storage under% RH} (ppm) / (80-20) (% RH)
3) From the CTE and CHE of the optical film obtained in the above 1) and 2), CHE / CTE in the direction X (preferably MD direction) of the optical film is calculated.

(Tensile modulus)
As described above, the tensile elastic modulus of the optical film in the direction X parallel to the absorption axis of the polarizer in an environment of 40 ° C. and 20% RH is preferably 2 GPa or more in order to increase the thermal expansion force. More preferably, it is 3 GPa or more. On the other hand, in order to release the shrinkage applied to the polarizer, the tensile elastic modulus of the optical film in a 40 ° C., 20% RH environment is preferably 6 GPa or less, and more preferably 4.5 Gpa or less.

The tensile elastic modulus of the optical film at 40 ° C. and 20% RH can be measured by the same method as described above.
1) A test piece is obtained by cutting an optical film into a size of 100 mm (direction X parallel to the absorption axis of the polarizer, preferably MD direction) × 10 mm (preferably TD direction).
2) In accordance with JIS K7127, this test piece was pulled in the direction X (preferably MD direction) of the test piece using a Tensilon RTC-1225A manufactured by Orientec Co., Ltd. Measure the tensile modulus. The measurement is performed at 40 ° C. and 20% RH.

(Tg)
The glass transition temperature Tg of the optical film preferably satisfies the following formulas (1) to (3) at the same time.
(Formula 1) Ta>Tg> Tb
(Formula 2) Ta ≧ Tb + 80
(Formula 3) 150 ≧ Tg ≧ 100

  As described above, Tg of the optical film is a method in accordance with JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 type manufactured by Perkin Elmer) as the intermediate glass transition temperature (Tmg). Can be measured. The heating rate can be 20 ° C./min.

(Retardation)
The retardation R ₀ in the in-plane direction measured under the conditions of a measurement wavelength of 590 nm and 23 ° C. and 55% RH of the optical film is preferably −20 nm to 20 nm, and preferably −10 nm to 10 nm. More preferred. The retardation Rth in the thickness direction measured under the conditions of a measurement wavelength of 590 nm and 23 ° C. and 55% RH of the optical film is preferably −80 nm to 80 nm, more preferably −50 nm to 50 nm. . The optical film having such a retardation value is preferably used as a polarizing plate protective film (F1 or F4) for a liquid crystal display device, as will be described later.

Retardation _R0 and Rth are defined by the following equations, respectively.
Formula (I): R ₀ = (nx−ny) × d (nm)
Formula (II): Rth = {(nx + ny) / 2−nz} × d (nm)
(In formulas (I) and (II),
nx represents the refractive index in the slow axis direction x where the refractive index is maximum in the in-plane direction of the film;
ny represents the refractive index in the direction y perpendicular to the slow axis direction x in the in-plane direction of the film;
nz represents the refractive index in the thickness direction z of the film;
d (nm) represents the thickness of the film)

The retardations _R0 and Rth can be determined by the following method, for example.
1) The optical film is conditioned at 23 ° C. and 55% RH. The average refractive index of the optical film after humidity adjustment is measured with an Abbe refractometer or the like.
The optical film after 2) humidity, measuring the _{R 0} when the light is incident in parallel to the measurement wavelength 590nm to normal of the film surface, KOBRA21DH, in Oji Scientific Corporation.
3) With KOBRA21ADH, the in-plane slow axis of the optical film is used as the tilt axis (rotation axis), and light with a measurement wavelength of 590 nm is incident from the angle of θ (incident angle (θ)) with respect to the normal of the optical film surface The retardation value R (θ) when measured is measured. The in-plane slow axis of the optical film refers to a slow axis in a direction in which the refractive index is maximum within the optical film plane. The retardation value R (θ) can be measured at 6 points every 10 °, with θ ranging from 0 ° to 50 °. The in-plane slow axis of the optical film can be confirmed by KOBRA21ADH.
4) nx, ny, and nz are calculated by KOBRA21ADH from the measured R ₀ and R (θ) and the above-described average refractive index and film thickness, and Rth at a measurement wavelength of 590 nm is calculated. The measurement of retardation can be performed under conditions of 23 ° C. and 55% RH.

  The angle θ1 (orientation angle) formed by the in-plane slow axis of the optical film and the width direction of the optical film is preferably −1 ° to + 1 °, more preferably −0.5 ° to + 0.5 °. It is. The orientation angle θ1 of the optical film can be measured using an automatic birefringence meter KOBRA-WR (Oji Scientific Instruments).

(Haze, total light transmittance)
The haze of the optical film is preferably 1.0% or less, and more preferably 0.5% or less. The haze of the optical film can be measured with a haze meter (turbidimeter) (model: NDH 2000, manufactured by Nippon Denshoku Co., Ltd.) in accordance with JIS K-7136. The total light transmittance of the optical film is preferably 90% or more, and more preferably 93% or more.

  The optical film can be preferably used as a polarizing plate protective film. Examples of the polarizing plate protective film include not only a protective film having no retardation control function but also a retardation film having a retardation control function.

  The optical film can be manufactured by a solution casting film forming method or a melt casting film forming method. It is preferable that the optical film is manufactured by a solution casting film forming method because melting at a high temperature is unnecessary and a resin having a relatively large molecular weight is easily formed. That is, the production process of the optical film by the solution casting method is 1) a process of obtaining the dope by dissolving each of the above components in a solvent, 2) after casting the dope on an endless metal support, A step of drying to obtain a film-like material, 3) a step of peeling the obtained film-like material from the metal support, 4) a step of stretching the peeled film-like material, and 5) a step of winding up the obtained film. including.

  4) In the drying and stretching step, it is preferable that the peeled film is dried and further stretched. By stretching, it is easy to increase the degree of orientation of the resin, lower the CHE / CTE of the resulting film, and increase the tensile elastic modulus.

  The stretching may be performed in at least one direction, and is preferably performed in two directions. Stretching in two directions (biaxial stretching) is preferably performed in the casting direction (MD direction) and the width direction (TD direction), respectively.

  The draw ratio is the total of the casting direction (MD direction) and the width direction (TD direction), preferably in the range of 110% to 400%, more preferably in the range of 120 to 300%, and still more preferably. It is in the range of 130 to 250%. By increasing the draw ratio, it is easy to increase the tensile modulus of the resulting film; it is easy to decrease CHE / CTE. The draw ratio (%) is defined as the length of the film-like product after stretching (in the drawing direction) / the length of the film-like material before drawing (in the drawing direction) × 100. For example, when the draw ratio in the casting direction is 110% and the draw ratio in the width direction is 120%, the sum of the draw ratios is defined as the sum thereof; 100+ (10 + 20) = 130%.

  The stretching temperature is preferably Tg to (Tg + 50) ° C of the optical film, and more preferably Tg to (Tg + 40) ° C. Specifically, when obtaining the optical film which has a cellulose ester as a main component, extending | stretching temperature can be about 100-200 degreeC. When extending | stretching with a tenter extending | stretching apparatus, it is preferable that the residual solvent amount of the film-form thing at the time of a tenter extending | stretching start is 20-100 mass%.

  5) In the winding process, the obtained long optical film is usually wound into a roll in the long direction to obtain a wound body. The length of the long optical film can be in the range of 100 to 10,000 m. The width of the long optical film can be in the range of 1 to 4 m, preferably in the range of 1.4 to 3 m.

  FIG. 4 is a schematic diagram illustrating an example of the configuration of the display panel. The figure is an example of a display panel for a liquid crystal display device. As shown in FIG. 4, the display panel 11 includes a liquid crystal cell 30, a first polarizing plate 50 disposed on the display side surface, and a second polarizing plate disposed on the backlight unit side surface. 70.

  The liquid crystal cell 30 has a pair of transparent substrates 31 and 33 and a liquid crystal layer 35 sandwiched between them.

  The transparent substrates 31 and 33 are transparent resin substrates or glass substrates, preferably glass substrates. The thickness of the transparent substrates 31 and 33 is preferably equal to or less than a certain value in order to reduce the thickness of the display device, and is preferably 0.3 mm or more and less than 0.7 mm, and is 0.3 to 0.5 mm. It is more preferable.

In order to make it easier to suppress panel bends, the glass substrate preferably has a thermal expansion coefficient of a certain value or less so that it can withstand the contraction force of the polarizer when it receives heat from the backlight unit. Specifically, the thermal expansion coefficient CTE of the glass substrate is preferably 30 × 10 ⁻⁷ to 50 × 10 ⁻⁷ cm / cm / ° C., and preferably 35 × 10 ⁻⁷ to 50 × 10 ⁻⁷ cm / cm / More preferably, it is ° C.

  When the thickness of the glass substrate is t (mm) and the length of the long axis of the display panel 11 is l (mm), t / l is preferably 0.0002 to 0.0005, and 0.0002 to 0 More preferred is .0004. When t / l is in the above range, the display panel 11 is likely to warp due to the contraction force of the polarizer because the major axis l of the display panel 11 is large and the thickness t of the glass substrate is small. Even in such a case, the warp of the display panel 11 can be reduced by setting the CHE / CTE and the tensile elastic modulus of the optical film within the above ranges.

  The pixel electrode for applying a voltage to the liquid crystal molecules can be disposed on one of the pair of transparent substrates 31 and 33 (for example, the transparent substrate 31). The counter electrode may be further disposed on the transparent substrate 21 on which the pixel electrode is disposed, or may be disposed on the other transparent substrate 33. The color filter can be usually disposed on the other transparent substrate 33.

  The display mode of the liquid crystal cell 30 may be any of STN, TN, OCB, HAN, VA (MVA, PVA), IPS, and the like. For example, in order to obtain high contrast, the VA (MVA, PVA) mode is used. Is preferred.

  The liquid crystal layer 35 includes liquid crystal molecules having negative or positive dielectric anisotropy, for example, when the liquid crystal cell 30 is a VA system. The liquid crystal molecules are liquid crystal when no voltage is applied (when no electric field is generated between the pixel electrode and the counter electrode) due to the alignment regulating force of the alignment film provided on the surface of the transparent substrate 31 on the liquid crystal layer side. The long axis of the molecule is oriented so as to be substantially perpendicular to the surface of the transparent substrate. Then, by applying an image signal (voltage) to the pixel electrode, the liquid crystal molecules are aligned so that the major axis thereof is in the horizontal direction with respect to the substrate surface, thereby changing the transmittance and reflectance of each sub-pixel. To display the image.

  The first polarizing plate 50 is disposed on the display-side surface of the liquid crystal cell 30, and includes a first polarizer 51, a protective film 53 (F1) disposed on the display-side surface, And a protective film 55 (F2) disposed on the surface of the polarizer 51 on the liquid crystal cell 30 side. The absorption axis of the first polarizer 51 is preferably parallel to the long axis of the display panel 11.

  The second polarizing plate 70 is disposed on the surface of the liquid crystal cell 30 on the backlight unit side, the second polarizer 71, and a protective film 73 (F3) disposed on the surface of the liquid crystal cell 30 side. And a protective film 75 (F4) disposed on the surface of the second polarizer 71 on the backlight unit side.

  The first polarizer 51 and the second polarizer 71 can be the aforementioned polarizers. Of the protective films F1 and F4, at least the protective film F1 can be the optical film described above. The direction X (preferably MD direction) of the protective film F1 and the absorption axis of the first polarizer 51 are preferably parallel to each other. Similarly, it is preferable that the direction X (preferably MD direction) of the protective film F4 and the absorption axis of the second polarizer 71 are parallel to each other.

  As described above, the absorption axis of the first polarizer 51 is often parallel to the long axis of the display panel 11. Therefore, when the first polarizer 51 receives heat from the backlight, the first polarizer 51 easily contracts in the long axis direction of the display panel 11 (the long side direction of the display). On the other hand, the absorption axis of the second polarizer 71 is often parallel to the short axis of the display panel 11. Therefore, the second polarizer 71 is likely to contract in the short axis (the short side direction of the display) of the display panel 11.

  The contraction force of the first polarizer 51 can be canceled by the expansion force of the protective film 53 (F1); the contraction force of the second polarizer 71 can be canceled by the expansion force of the protection film 75 (F4). it can.

  In particular, the contraction force of the first polarizer 51 contracting in the major axis direction of the display panel 11 is larger than the contraction force of the second polarizer 71 contracting in the minor axis direction of the display panel 11. Therefore, it is preferable to apply the above-described optical film to the protective film 53 (F1). Thus, it is preferable that the long axis of the display panel 11 (the long side direction of the display) and the direction X (preferably the MD direction) of the protective film 53 (F1) be parallel to each other. Thereby, panel bend can be reduced effectively.

  The protective film F2 or F3 can function as a retardation film. The retardation film is not particularly limited, and may be, for example, a cellulose ester film. Examples of cellulose esters contained in the cellulose ester film include cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose acetate propionate benzoate, cellulose propionate, and cellulose butyrate. , Cellulose acetate biphenylate, cellulose acetate propionate biphenylate, and the like.

The cellulose ester preferably has a total acyl group substitution degree of 1.5 or more and 2.5 or less, and more preferably satisfies the following formulas (a) and (b).
Formula (a) 2.0 ≦ X + Y ≦ 2.5
Formula (b) 0 ≦ Y ≦ 1.5
(Wherein, X represents the degree of substitution of the acetyl group, and Y represents the degree of substitution of the propionyl group or butyryl group, or a mixture thereof)

  The weight average molecular weight (Mw) of the cellulose ester is preferably 75,000 or more, more preferably 100,000 to 1,000,000 from the viewpoint of film strength and appropriate viscosity at the time of film formation. It is especially preferable that it is ˜500,000.

  The cellulose ester film may be a single layer film or a laminated film. When the cellulose ester film is a laminated film, it is a laminate of a core layer mainly composed of a cellulose ester having a low degree of substitution and a skin layer mainly composed of a cellulose ester having a high degree of substitution disposed on both sides thereof. It is preferable. The cellulose ester having a low degree of substitution preferably satisfies the above formulas (a) and (b), and the cellulose ester having a high degree of substitution preferably has a total acyl group substitution degree of more than 2.5, and preferably 2.7. It is preferable that it is 2.98 or less, and it is preferable that all acyl groups contained in the cellulose ester are acetyl groups.

  The retardation film may be a commercially available product. For example, examples of the retardation film for vertical alignment (VA) include Konica Minoltak KC8UCR3, KC8UCR4, KC8UCR5, KC4FR, KC4KR, KC4DR, KC4SR (above, manufactured by Konica Minolta Co., Ltd.).

  The retardation of the retardation film can be set according to the type of liquid crystal cell to be combined. For example, the retardation Ro (590) in the in-plane direction measured at 23 ° C. and 55% RH at a wavelength of 590 nm is preferably in the range of 30 to 150 nm, and the retardation Rt in the thickness direction ( 590) is preferably in the range of 70 to 300 nm. A retardation film having a retardation in the above range can be preferably used as a retardation film such as a VA liquid crystal cell. The retardation Ro in the in-plane direction and the retardation Rt in the thickness direction can be defined and measured in the same manner as described above.

  The thickness of the retardation film is not particularly limited, but is preferably 10 to 250 μm, more preferably 10 to 100 μm, and particularly preferably 30 to 60 μm.

  FIG. 5 is a schematic diagram illustrating another example of the configuration of the display panel. The figure is an example of a display panel for an organic EL display device. As shown in FIG. 5, the display panel 11 ′ can include an organic EL element 90 and a circularly polarizing plate 110 disposed on the display surface. When the display panel 11 'is used, the above-described backlight unit 13 is omitted in FIG.

The organic EL element 90 can include a light reflecting electrode 91, a light emitting layer 93, a transparent electrode layer 95, and a transparent substrate 97. The transparent substrate 97 can be the same as described above. That is, the transparent substrate 97 is preferably a glass substrate, and the coefficient of thermal expansion CTE is preferably 30 × 10 ⁻⁷ to 50 × 10 ⁻⁷ cm / cm / ° C., and 35 × 10 ⁻⁷ to 50 × 10. More preferably, it is ⁻⁷ cm / cm / ° C.

  The circularly polarizing plate 110 includes a polarizer (linear polarizer) 111 and a protective film 113 disposed between the polarizer 111 and the organic EL element 90.

  The polarizer 111 may be the aforementioned polarizer; the protective film 113 may be the aforementioned optical film. The crossing angle between the absorption axis of the polarizer 111 and the in-plane slow axis of the protective film 113 can be set to be 40 to 50 °, preferably 45 °. Moreover, it is preferable that the absorption axis of the polarizer 111 and the direction X (preferably MD direction) of the protective film 113 are parallel to each other. The absorption axis of the polarizer 111 is preferably parallel to the long axis of the display panel 11 '.

<About the backlight unit 13>
The backlight unit 13 may be a sidelight (edge light) type surface light source in which a light source is disposed on the side surface of the light guide plate, or a direct type surface light source in which known light sources are arranged under a diffusion plate. The light source can be an LED or the like.

  Thus, in this embodiment, the warp of the display panel 11 is reduced. Thereby, even if the overlap width H between the display panel 11 and the bezel 15B of the housing 15 is reduced, the display panel 11 can be prevented from protruding outside the housing 15 and can be stably held in the housing 15. Accordingly, the display panel 11 can be stably held in the housing 15 without being fixed to the housing 15 with an adhesive or the like, and the display area can be increased.

(Second embodiment)
FIG. 6 is a partial cross-sectional view showing a cross section of the display device of the second embodiment. As shown in FIG. 6, the display device 20 is the same as that shown in FIG. 2 except that the casing 25 includes a back member 25 </ b> A, a bezel 25 </ b> B, and a top chassis 25 </ b> C and a middle chassis 25 </ b> D for connecting them. It can be configured similarly.

  The back member 25 </ b> A is a plate-like member that covers the back surface of the display panel 11. The bezel 25B is a frame-like member that covers the peripheral edge and the side surface of the display surface of the display panel 11. The overlapping width H between the bezel 25B and the display panel 11 can be the same as described above.

  The top chassis 25C and the middle chassis 25D connect the bezel 25B and the back member 25A. The materials of the top chassis 25C and the middle chassis 25D can be the same as those of the back member 25A and the bezel 25B described above.

  EXAMPLES Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

1. Optical Film Material CAP: Cellulose acetate propionate with acetyl group substitution degree 0.19, propionyl group substitution degree 2.56, acyl group total substitution degree 2.75, weight average molecular weight Mw = 200,000, Tg = 143 ° C.
TAC: cellulose triacetate having an acetyl group substitution degree of 2.87 and an acyl group total substitution degree of 2.87 (weight average molecular weight Mw = 300,000)
SPS resin: Syndiotactic polystyrene resin (weight average molecular weight Mw = 180,000)
Polyvinyl acetate resin: polyvinyl acetate (CHE: 70 ppm /% RH, CTE: 200 ppm / ° C., CHE / CTE: 0.35, weight average molecular weight Mw = 200,000, Tg = 36 ° C.)
PEN: Polyethylene naphthalate (weight average molecular weight Mw = 100,000)
MS: Methyl methacrylate / styrene (80/20 molar ratio) copolymer (weight average molecular weight Mw = 100,000)
Methyl methacrylate / styrene / maleic anhydride copolymer (32/50/18 molar ratio) (CHE = 15 ppm /% RH, CTE = 62 ppm / ° C., CHE / CTE = 0.24, tensile modulus = 3.0 GPa, (Weight average molecular weight Mw = 170,000, Tg = 125 ° C.)
MMA / MA copolymer (95/5 molar ratio) (weight average molecular weight Mw = 300,000)
PP: Polypropylene (weight average molecular weight Mw = 100,000)

2. Production of optical film (Optical film 101)
100 parts by mass of SPS resin and 2,2′-methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (stock) as an ultraviolet absorber LADE made by ADEKA company, molecular weight 659) is 3.0 parts by mass, and ELECUT S412 (manufactured by Takemoto Yushi Co., Ltd.) is 0.50 parts by mass as a peeling aid at 70 ° C. under reduced pressure using a vacuum nauter mixer After drying for 3 hours, it was put into a single screw extruder and melt-kneaded at 250 ° C. in a nitrogen atmosphere. Then, it extruded from the die | dye on the 1st cooling roll whose surface temperature is 90 degreeC. And the sheet-like resin extruded on the 1st cooling roll was pressed with the touch roll. The surface temperature of the touch roll was 80 ° C. Thereafter, the obtained sheet-like resin was further cooled and solidified on the second and third cooling rolls to obtain a film.

  Next, the obtained film was stretched 1.5 times in the conveyance direction (MD direction) by zone stretching and 1.5 times in the width direction (TD direction) by tenter stretching, and the optical film 101 having a film thickness of 40 μm. Got.

(Optical film 103, 105)
Optical films 103 and 105 having a thickness of 40 μm were obtained in the same manner as the optical film 101 except that 100 parts by mass of the SPS resin was changed as shown in Table 1.

(Optical film 102)
The following components were sufficiently dissolved with stirring and heating to prepare a dope.
(Composition of dope)
CAP (acetyl acetate substitution degree 0.19, propionyl group substitution degree 2.56, cellulose acetate propionate having an acyl group total substitution degree 2.75, weight average molecular weight Mw = 200,000, Tg = 143 ° C.): 50 parts by mass Polyvinyl acetate (CHE: 70 ppm /% RH, CTE: 200 ppm / ° C., CHE / CTE: 0.35, weight average molecular weight Mw = 200,000, Tg = 36 ° C.): 50 parts by mass UV absorber 2,2′- Methylenebis [6- (2H-benzotriazol-2-yl) -4- (1,1,3,3-tetramethylbutyl) phenol] (LA31 manufactured by ADEKA Corporation, molecular weight 659): 3.0 parts by mass Agent R972V (manufactured by Nippon Aerosil Co., Ltd., silica particles, average particle size 16 nm): 0.30 parts by weight Peeling aid ELECUT S412 (manufactured by Takemoto Yushi Co., Ltd.) 50 parts by mass Dichloromethane: 300 parts by mass Ethanol: 40 parts by mass

  The prepared dope was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100%, and the obtained film-like material was peeled off from the stainless steel band support with a peeling tension of 162 N / m.

  Subsequently, the solvent was evaporated from the peeled film-like material at 35 ° C. and slit to a width of 1 m. Then, it was dried at a drying temperature of 135 ° C. while being stretched 1.5 times in the transport direction (MD direction) by zone stretching and 1.5 times in the width direction (TD direction) by tenter stretching. The residual solvent amount at the start of stretching by the tenter was 8.0%. Thereby, an optical film 102 having a film thickness of 40 μm was obtained.

(Optical film 104, 106-108)
Optical films 104 and 106 to 108 were obtained in the same manner as described above except that the type of resin was changed as shown in Table 1.

  The obtained optical film was measured for the hygroscopic expansion coefficient CHE, the thermal expansion coefficient CTE, the tensile elastic modulus at 40 ° C., and the glass transition temperature Tg by the following methods.

(CHE / CTE of optical film)
1) The optical film was cut out to a predetermined size to obtain a test piece. The CTE (ppm / ° C.) in the MD direction (direction X) of the test piece was measured by the TMA method according to ASTM E-831 or JIS K7197.
2) The test piece of the optical film prepared in the same manner as described above was stored for 24 hours in an environment of 23 ° C. and 20% RH, and the dimension in the MD direction (direction X) and in an environment of 23 ° C. and 80% RH. The dimension in the MD direction (direction X) after storage for 24 hours was measured. The obtained measured value was applied to the following formula to obtain CHE (ppm /% RH) in the MD direction (direction X) of the optical film (see the following formula).
CHE (ppm /% RH) = {(MD direction dimension of specimen after storage at 23 ° C. and 80% RH−MD direction dimension of specimen after storage at 23 ° C. and 20% RH) / 23 ° C. and 20% RH Dimension of specimen in MD direction after storage} (ppm) / (80-20) (% RH)
3) CHE / CTE in the MD direction (direction X) of the optical film was calculated from the CTE and CHE of the optical film obtained in 1) and 2) above.

(Tensile modulus of optical film)
1) The optical film was cut into a size of 100 mm (MD direction) × 10 mm (TD direction) to obtain a test piece.
2) In accordance with JIS K7127, the test piece was pulled in the MD direction (direction X) of the test piece using a Tensilon RTC-1225A manufactured by Orientec Co., Ltd. ) Was measured. The measurement was performed at 40 ° C. and 20% RH.

(Glass transition temperature Tg)
The glass transition temperature Tg of the optical film was measured as a midpoint glass transition temperature (Tmg) by a method based on JIS K7121 (1987) using a differential scanning calorimeter (DSC-7 model manufactured by Perkin Elmer). . The heating rate was 20 ° C./min.

Table 1 shows the compositions and physical properties of the optical films 101 to 108.

3. Production of retardation film (retardation film D)
The following components were stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin to obtain a fine particle dispersion 1.
(Fine particle dispersion 1)
Fine particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.): 11 parts by mass Ethanol: 89 parts by mass

The above-prepared fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride and sufficiently stirred. The resulting solution was dispersed with an attritor so that the secondary particles had a predetermined particle size, and then filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1 did.
(Fine particle addition liquid 1)
Methylene chloride: 99 parts by mass Fine particle dispersion 1: 5 parts by mass

  A main dope solution having the following composition was prepared. First, after adding methylene chloride and ethanol to the pressure dissolution tank, the cellulose acetate, sugar ester compound, polycondensation ester, retardation increasing agent and fine particle additive liquid 1 having an acetyl group substitution degree of 2.40 are added with stirring. did. This was heated and dissolved completely with stirring. The obtained solution was used as Azumi filter paper No. manufactured by Azumi Filter Paper Co., Ltd. The main dope solution was prepared by filtration using 244.

(Main dope composition)
Methylene chloride: 365 parts by mass Ethanol: 50 parts by mass Cellulose acetate (acetyl substitution degree 2.40): 84 parts by mass Sugar ester 1: Saccharose benzoate having an average substitution degree of 5.5: 10 parts by mass Polycondensation ester: (phthalic acid / Adipic acid / 1,2-propanediol = 25/75/100 molar condensate with both ends sealed with a benzoate group, molecular weight 440): 3 parts by mass Retardation adjuster (compound A): 3 parts by mass Particulate additive solution 1: 1 parts by mass

  The obtained main dope solution was evaporated on a stainless steel belt support until the amount of residual solvent in the cast film was 75%. The obtained film was peeled from the stainless steel belt support with a peeling tension of 130 N / m. The film-like material obtained by peeling was stretched 30% in the width direction using a tenter while applying heat at 150 ° C. The residual solvent at the start of stretching was 15%.

  Next, drying was terminated while the drying zone was conveyed by a number of rolls. The drying temperature was 130 ° C. and the transport tension was 100 N / m. As described above, a retardation film D having a dry film thickness of 35 μm was obtained.

4). Production of liquid crystal display device (Example 1)
Production of Polarizer A polyvinyl alcohol film having a thickness of 125 μm was swollen with water at 35 ° C. The obtained film was immersed in an aqueous solution consisting of 0.075 g of iodine, 5 g of potassium iodide and 100 g of water for 60 seconds, and further immersed in an aqueous solution at 45 ° C. consisting of 3 g of potassium iodide, 7.5 g of boric acid and 100 g of water. . The obtained film was uniaxially stretched under conditions of a stretching temperature of 55 ° C. and a stretching ratio of 5 times. The uniaxially stretched film was washed with water and dried to obtain a polarizer having a thickness of 26 μm.

Preparation of polarizing plate 1) Preparation of first polarizing plate The optical film 101 prepared above was prepared as a polarizing plate protective film. Then, as shown below, the optical film 101 was alkali saponified and then washed with water, neutralized and washed with water.
Saponification process 2M-NaOH 50 ° C. 90 seconds Water washing process Water 30 ° C. 45 seconds Neutralization process 10% HCl 30 ° C. 45 seconds Water washing process Water 30 ° C. 45 seconds Thereafter, the obtained optical film 101 was dried at 80 ° C. . Similarly, the produced retardation film D was also alkali saponified.

  Then, the above-described optical film 101 subjected to alkali saponification treatment was bonded to one surface of the produced polarizer using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive. Similarly, the retardation film D subjected to alkali saponification treatment was bonded to the other surface of the polarizer using a 5% aqueous solution of completely saponified polyvinyl alcohol as an adhesive. The bonding was performed so that the MD direction (absorption axis) of the polarizer and the MD direction of the optical film 101 were parallel. The laminated laminate was dried at 60 ° C. to obtain a first polarizing plate.

2) Production of second polarizing plate The produced optical film 101 was prepared as a protective film, and the surface was subjected to alkali saponification treatment in the same manner as described above.

  Then, the above-prepared optical film 101 prepared by alkali saponification on one surface of the prepared polarizer is completely saponified, respectively, on the other surface of the polarizer. A 5% aqueous polyvinyl alcohol solution was bonded as an adhesive. The bonding was performed so that the MD direction (absorption axis) of the polarizer and the MD direction of the optical film 101 were parallel. The laminated laminate was dried at 60 ° C. to obtain a second polarizing plate.

3) Production of Display Panel As a liquid crystal cell, a VA liquid crystal cell having two glass substrates having a thickness of 0.3 mm and a liquid crystal layer disposed therebetween was prepared. Then, the prepared first polarizing plate is bonded to the display surface of the prepared liquid crystal cell via a 25 μm-thick double-sided tape (substrate-less tape MO-3005C) manufactured by Lintec; backlight of the liquid crystal cell A second polarizing plate was bonded to the side surface via the double-sided tape to obtain a display panel. The bonding was performed so that the retardation film D of each polarizing plate was in contact with the glass substrate of the liquid crystal cell.

The warpage amount and mounting suitability of the obtained display panel were evaluated by the following methods.
(Warpage amount)
The obtained display panel was allowed to stand at room temperature of 23 ° C. and 55% for half a day, and then stored in a thermostat of 40 ° C. and 90% RH for 24 hours. Thereafter, the display panel was taken out, put in a 40 ° C. dry thermo, and dried for 2 hours. The amount of warpage of the panel obtained after drying was measured immediately. The amount of warpage of the panel was measured by measuring the height from the horizontal plane at the four corners of the panel, and taking the average value thereof.

(Mountability)
The produced display panel 11 was accommodated in the housing 15 (see FIG. 1) having the bezel 15B. The edge side surface of the display panel 11 was not fixed with an adhesive or the like. The minimum value of the overlap width H between the display panel 11 and the bezel 15B was 10 mm (0.83% with respect to the long axis of the display panel 11). Then, after leaving still at room temperature of 23 degreeC55% for half a day, it put into the thermostat of 40 degreeC90% RH, and preserve | saved for 24 hours. Thereafter, the display panel was taken out, put in a 40 ° C. dry thermo, and dried for 2 hours. At that time, the holding property of the display panel was evaluated by the following index.
○: The end of the display panel is not in contact with the inner wall surface of the bezel and is stably held in the housing. △: The end of the display panel is in contact with the end of the bezel, and is stable in the housing. ×: The edge of the display panel protrudes outside the case and cannot be held in the case

4) Production of liquid crystal display device After removing the display panel (polarizing plate / liquid crystal cell / laminate of polarizing plate) from the 55-inch display BRAVIA KLV-40J3000 (VA method) manufactured by SONY, the display panel produced above was placed. Thus, a liquid crystal display device 301 was obtained. The attached liquid crystal display panel was set so that the slow axis of the retardation film D and the slow axis of the polarizing plate previously attached were parallel. And the display nonuniformity was evaluated with the following method.

(Display unevenness)
The obtained liquid crystal display device was stored for 30 minutes with the backlight turned on in an environment of a temperature of 23 ° C. and a humidity of 55% RH. Thereafter, whether or not fine optical unevenness occurred on the display screen of the liquid crystal display device was evaluated according to the following criteria.
○: No unevenness Δ: Several weak unevennesses ×: Strong irregularity with regularity

(Examples 2-6, Comparative Examples 1-2)
A polarizing plate was produced in the same manner as in Example 1 except that the types of the protective films F1 and F4 were changed as shown in Table 2, and liquid crystal display devices 302 to 308 were obtained. And evaluation similar to Example 1 was performed.

(Example 7)
A polarizing plate was produced in the same manner as in Example 6 except that the thickness of the glass substrate was changed to 0.5 mm, and a liquid crystal display device 309 was obtained. And evaluation similar to Example 1 was performed.

(Example 8)
A polarizing plate was produced in the same manner as in Example 6 except that the thickness of the polarizer was changed to 15 μm, and a liquid crystal display device 310 was obtained. And evaluation similar to Example 1 was performed.

Example 9
A liquid crystal display device 311 was produced in the same manner as in Example 6 except that a glass substrate having CTE as shown in Table 2 was used. And evaluation similar to Example 1 was performed.

(Example 10)
A liquid crystal display device 312 was produced in the same manner as in Example 6 except that the length of the long axis of the glass substrate was changed as shown in Table 2. And evaluation similar to Example 1 was performed.

(Example 11)
A liquid crystal display device 313 was produced in the same manner as in Example 6 except that the length of the long axis of the glass substrate and the bezel width of the display device were changed as shown in Table 2, respectively. And evaluation similar to Example 1 was performed.

(Example 12)
A liquid crystal display device 314 was produced in the same manner as in Example 6 except that the bezel width of the display device was changed as shown in Table 2. And evaluation similar to Example 1 was performed.

Table 2 shows the evaluation results of Examples 1 to 12 and Comparative Examples 1 and 2.

  As shown in Table 2, as the protective film F1, the display panels of Examples 1 to 12 including an optical film in which the CHE / CTE and the tensile elastic modulus at 40 ° C. are both adjusted to a predetermined range are warped. Less than 2.5 mm. And even if the overlap width H between the front bezel and the display panel is reduced, these display panels are stably held in the housing (excellent mounting suitability), and display unevenness of the liquid crystal display device is also suppressed. I found out.

  In contrast, the display panels of Comparative Examples 1 and 2 had a large warp of 4.1 mm or more. Accordingly, it was found that when the overlap width H between the front bezel and the display panel is reduced, the display panel protrudes out of the housing and is not stably held, and the mounting suitability is low. It was also found that display unevenness of the liquid crystal display device also occurred.

  It can be seen that the display panel of Example 8 has less warpage of the panel than Example 6 because the thickness of the polarizer is small. Since the display panel of Example 9 has a CTE of the glass substrate lower than that of Example 6, it can be seen that there is less warping of the panel. Since the display panel of Example 10 has t / l smaller than that of Example 6, it can be seen that the panel can be stably held even with a small overlap width H (0.7%) although the panel warpage slightly increases.

  This application claims the priority based on Japanese Patent Application No. 2013-242970 for which it applied on November 25, 2013. The contents described in the application specification and the drawings are all incorporated herein.

  ADVANTAGE OF THE INVENTION According to this invention, a panel bend can be reduced and the display apparatus which can make the overlap width of a bezel and a panel small by it can be provided.

10, 20 Display device 11, 11 ′ Display panel 15, 25 Housing 15A, 25A Back member 15B, 25B Bezel 30 Liquid crystal cell 31, 33, 97 Transparent substrate 35 Liquid crystal layer 50 First polarizing plate 51 First polarizer 53 Protective film (F1)
55 Protective film (F2)
70 Second polarizing plate 71 Second polarizer 73 Protective film (F3)
75 Protective film (F4)
DESCRIPTION OF SYMBOLS 90 Organic EL element 91 Light reflection electrode 93 Light emitting layer 95 Transparent electrode layer 110 Circularly polarizing plate 111 Polarizer 113 Protective film

Claims (9)

A display device comprising: a display panel; and a housing that houses the display panel and has a bezel that covers a peripheral portion of a display surface of the display panel,
The edge side surface of the display panel is not fixed to the housing via an adhesive,
The display panel includes a display element and a polarizing plate disposed on at least one surface of the display element,
The polarizing plate includes a polarizer and an optical film disposed on the polarizer,
The ratio CHE / CTE of the hygroscopic expansion coefficient CHE in the direction X parallel to the absorption axis of the polarizer of the optical film and the thermal expansion coefficient CTE in the direction X is 0.7 or less, and the environment is 40 ° C. and 20% RH. The display apparatus whose tensile elastic modulus of the said direction X below is 2-6GPa.   The display device according to claim 1, wherein a minimum value of an overlap width H between the bezel and the display panel is 0.3 to 5.0% with respect to a length of a major axis of the display panel.   The display device according to claim 1, wherein the polarizer has a thickness of 5 to 26 μm.   The display device according to claim 1, wherein the display element is a liquid crystal cell. The liquid crystal cell includes a liquid crystal layer and a pair of glass substrates sandwiching the liquid crystal layer,
The display according to claim 4, wherein t / l is 0.0002 to 0.0005, where t (mm) is the thickness of the glass substrate and l (mm) is the major axis length of the display panel. apparatus. The display device according to claim 5, wherein the glass substrate has a thermal expansion coefficient CTE of 30 × 10 ⁻⁷ to 50 × 10 ⁻⁷ cm / cm / ° C. Further including a backlight,
The display panel includes the liquid crystal cell, a first polarizing plate disposed on a display surface of the liquid crystal cell, and a second polarizing plate disposed on the backlight side surface of the liquid crystal cell,
The first polarizing plate is disposed on the surface of the first polarizer, the protective film F1 disposed on the display side surface of the first polarizer, and the surface of the first polarizer on the liquid crystal cell side. Protective film F2 made,
The second polarizing plate includes a second polarizer, a protective film F3 disposed on the liquid crystal cell side surface of the second polarizer, and the backlight side surface of the second polarizer. And a protective film F4 disposed in
The display device according to claim 4, wherein at least the protective film F1 is the optical film.   The display device according to claim 7, wherein the direction X of the protective film F1 and the absorption axis direction of the first polarizer coincide.   The display device according to claim 8, wherein a major axis of the display panel and an absorption axis of the first polarizer are parallel to each other.

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