JP5604331B2 - Liquid crystal display device and manufacturing method thereof - Google Patents

Description

  Provided are a liquid crystal display device with high display quality in which fluctuations of a polarizing plate due to environmental factors are alleviated and a manufacturing method thereof.

  A liquid crystal display device generally includes a liquid crystal cell, polarizing plates disposed on both sides of the liquid crystal cell, and a backlight. Uniformity is important in liquid crystal display devices. In particular, the occurrence of partial light leakage during black display impairs uniformity and lowers display quality as a display. Therefore, a liquid crystal display device that does not impair such display quality is required.

  In addition, liquid crystal display devices are becoming thinner and backlights are also becoming thinner. For this reason, a light source that generates a large amount of light is used as the light source of the backlight, but heat is also generated accordingly. For example, a light-emitting cold cathode tube is thin and still needs to emit a large amount of light. A large amount of heat is generated by the generation of a large amount of light in a thin cold cathode tube, and the maximum temperature rises to about 50 ° C. at the portion in contact with the liquid crystal panel.

  When the heat of the backlight is transmitted to the liquid crystal cell, the liquid crystal cell is warped, and the warped portion is pressed against the module frame, thereby causing light leakage at the corner portion.

  For such a backlight, a method of inserting a heat insulating sheet between the backlight and the liquid crystal cell has been proposed in order to reduce the influence of heat from the backlight (Patent Document 1). However, since a heat insulating sheet is required compared with the conventional one, there is a problem that the cost increases, the liquid crystal display device becomes thick, and the number of steps in the manufacturing process of the display device increases, and these problems can be easily solved. Development of was desired. Furthermore, no consideration has been given to the viewing side that is affected by heat transmitted through the housing.

JP 2005-321593 A

  The present invention relates to a liquid crystal display device having a liquid crystal cell, a pair of polarizing plates disposed on both sides of the liquid crystal cell via an adhesive layer, and a backlight, in which temperature unevenness occurs as the backlight. The present invention provides a liquid crystal display device with good display quality that has no unevenness of brightness and excellent in-plane uniformity without using an additional configuration or increasing the thickness of the liquid crystal display device, and a method for manufacturing the same. For the purpose.

  As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by a liquid crystal display device shown below, and have completed the present invention.

The said subject of this invention can be achieved with the following structures and manufacturing methods.
<1>
A liquid crystal display device having a liquid crystal cell, a pair of polarizing plates disposed on both sides of the liquid crystal cell via an adhesive layer, and a backlight, wherein at least one of the pair of polarizing plates and the polarizing plate A liquid crystal display device characterized in that the pressure-sensitive adhesive layer in contact with satisfies the following formulas (I) and (II) in an environment of 25 ° C. and 60% RH.
(I) 0.99856 ≦ N _MD / P _MD ≦ 0.99952
(II) 0.9970 ≦ N _TD / P _TD ≦ 0.9990
(Here, N _MD is the length of the portion where the pressure-sensitive adhesive layer in the absorption axis parallel to the direction of the polarizing plate is in contact with the liquid crystal cell, P _MD is a direction parallel to the absorption axis of the polarizing plate N _TD is the length of the portion where the pressure-sensitive adhesive layer is in contact with the liquid crystal cell in the direction perpendicular to the absorption axis of the polarizing plate, and P _TD is the polarization length of the polarizing plate . (This is the length of the polarizing plate in the direction perpendicular to the absorption axis of the plate.)
<2>
<1> characterized in that the viewing side polarizing plate of the liquid crystal display device and the adhesive layer in contact with the viewing side polarizing plate satisfy the above formulas (I) and (II) among the pair of polarizing plates. The liquid crystal display device described.
<3>
The pressure-sensitive adhesive layer in contact with at least one of the pair of polarizing plates and the polarizing plate satisfies the following formulas (I ′) and (II ′) in an environment of 25 ° C. and 60% RH. Liquid crystal display device.
(I ′) 0.9988 ≦ N _MD / P _MD ≦ 0.999928
(II ′) 0.9975 ≦ N _TD / P _TD ≦ 0.9985
(Here, N _MD is the length of the portion where the pressure-sensitive adhesive layer in the absorption axis parallel to the direction of the polarizing plate is in contact with the liquid crystal cell, P _MD is a direction parallel to the absorption axis of the polarizing plate N _TD is the length of the portion where the pressure-sensitive adhesive layer is in contact with the liquid crystal cell in the direction perpendicular to the absorption axis of the polarizing plate, and P _TD is the polarization length of the polarizing plate . (This is the length of the polarizing plate in the direction perpendicular to the absorption axis of the plate.)
The present invention is an invention according to the above <1> to <3>, but hereinafter, other matters (for example, the following [1] to [3]) are also described.
[1]
A liquid crystal display device having a liquid crystal cell, a pair of polarizing plates disposed on both sides of the liquid crystal cell via an adhesive layer, and a backlight, wherein at least one of the pair of polarizing plates and the polarizing plate A liquid crystal display device characterized in that the pressure-sensitive adhesive layer in contact with satisfies the following formulas (I) and (II) in an environment of 25 ° C. and 60% RH.
(I) 0.99856 ≦ N _MD / P _MD ≦ 0.99952
(II) 0.9970 ≦ N _TD / P _TD ≦ 0.9990
(Here, N _MD is the length of the portion where the pressure-sensitive adhesive layer in the absorption axis parallel to the direction of the polarizing plate is in contact with the liquid crystal cell, P _MD is a direction parallel to the absorption axis of the polarizing plate N _TD is the length of the portion where the pressure-sensitive adhesive layer is in contact with the liquid crystal cell in the direction perpendicular to the absorption axis of the polarizing plate, and P _TD is the polarization length of the polarizing plate. (This is the length of the polarizing plate in the direction perpendicular to the absorption axis of the plate.)
[2]
[1], wherein the viewing-side polarizing plate of the liquid crystal display device and the adhesive layer in contact with the viewing-side polarizing plate satisfy the formulas (I) and (II) among the pair of polarizing plates. Liquid crystal display device.
[3]
A method of manufacturing a liquid crystal display device comprising a liquid crystal cell, a pair of polarizing plates disposed on both sides of the liquid crystal cell via an adhesive layer, and a backlight, wherein at least one of the pair of polarizing plates is A method for producing a liquid crystal display device, wherein the equilibrium moisture content is adjusted to 25 ° C. 30% RH or more and 25 ° C. 50% RH or less, and then bonded to the liquid crystal cell.

  According to the present invention, even when a backlight that causes temperature unevenness is used, there is no uneven brightness and in-plane uniformity without using an additional configuration or increasing the thickness of the liquid crystal display device. An excellent liquid crystal display device with good display quality and a method for manufacturing the same can be provided.

It is a figure explaining the measuring method of the dimension P of a polarizing plate, and the dimension N of an adhesive layer.

  Hereinafter, although the form for implementing this invention is demonstrated in detail, this invention is not limited to these. In the present specification, when a numerical value represents a physical property value, a characteristic value, etc., the description “(numerical value 1) to (numerical value 2)” means “(numerical value 1) or more and (numerical value 2) or less”. .

  As a result of intensive studies, the present inventors have found that the light leakage generated at the corner of the liquid crystal cell is related to the warp of the liquid crystal panel. It is assumed that the warpage of the liquid crystal panel is caused by the heat generated in the backlight, which induces a dimensional change of the polarizing plate and warps the glass of the liquid crystal cell. Furthermore, although it is speculated that the unevenness of brightness is caused by the warped liquid crystal cell colliding in the housing, it is not certain. In the liquid crystal display device of the present invention, it is considered that a liquid crystal display device having uniform display quality was obtained by suppressing changes in the size of the polarizing plate due to heat.

In order to reduce light leakage at the corners after the liquid crystal display device is turned on, the liquid crystal cell of the liquid crystal display device (with a polarizing plate bonded through an adhesive layer) is left at 25 ° C. and 60% RH for a certain period of time. The ratio N / P of the dimension P of the polarizing plate and the dimension N of the pressure-sensitive adhesive layer may be a value satisfying the following formulas (I) and (II). When N / P satisfies the following formulas (I) and (II), light leakage of the liquid crystal display device is reduced and luminance unevenness can be reduced.
The time to leave is not particularly defined as long as it becomes a steady state that does not show fluctuations with respect to temperature and humidity, but the time to reach the steady state varies depending on the shape of the polarizing plate, etc. It is preferable to perform the measurement after leaving for 1 week at 25 ° C. and 60% RH.
(I) 0.99856 ≦ N _MD / P _MD ≦ 0.99952
(II) 0.9970 ≦ N _TD / P _TD ≦ 0.9990
Here, N _MD is the length of the portion where the pressure-sensitive adhesive layer in the absorption axis parallel to the direction of the polarizing plate is in contact with the liquid crystal cell, the P _MD in the absorption axis parallel to the direction of the polarizing plate This is the length of the polarizing plate. N _TD is the length of the part where the pressure-sensitive adhesive layer is in contact with the liquid crystal cell in the direction orthogonal to the absorption axis of the polarizing plate, and P _TD is the length in the direction orthogonal to the absorption axis of the polarizing plate. This is the length of the polarizing plate.
The dimensional ratio is more preferably
(I ′) 0.9988 ≦ N _MD / P _MD ≦ 0.999928
(II ′) 0.9975 ≦ N _TD / P _TD ≦ 0.9985, and the intensity of luminance unevenness can be further suppressed.

  The effect of the present invention can be obtained if the viewing-side polarizing plate and the pressure-sensitive adhesive layer in contact with the viewing-side polarizing plate or the backlight-side polarizing plate and the pressure-sensitive adhesive layer in contact therewith are observed in the liquid crystal display device. In particular, when the viewing side polarizing plate satisfies the above dimensional ratio, the effect of reducing luminance unevenness can be enhanced.

<Polarizing plate>
Although the polarizer itself can be used as the polarizing plate, generally, a polarizer having a transparent protective film on one side or both sides of the polarizer is generally used.

<Polarizer>
The polarizer is not particularly limited, and various types can be used. Examples of the polarizer include hydrophilic polymer films such as polyvinyl alcohol film, partially formalized polyvinyl alcohol film, and ethylene / vinyl acetate copolymer partially saponified film, and two colors such as iodine and dichroic dye. Examples thereof include polyene-based oriented films such as those obtained by adsorbing volatile substances and uniaxially stretched, polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Among these, a polarizer composed of a polyvinyl alcohol film and a dichroic material such as iodine is preferable. The thickness of these polarizers is not particularly limited, but is generally about 5 to 80 μm.

  A polarizer obtained by dyeing a polyvinyl alcohol film with iodine and uniaxially stretching it can be produced, for example, by dyeing polyvinyl alcohol in an aqueous solution of iodine and stretching it 3 to 7 times the original length. If necessary, it can be immersed in an aqueous solution such as potassium iodide which may contain boric acid, zinc sulfate, zinc chloride and the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed before dyeing. In addition to washing the polyvinyl alcohol film surface with dirt and anti-blocking agents by washing the polyvinyl alcohol film with water, it also has the effect of preventing unevenness such as uneven coloring by swelling the polyvinyl alcohol film. is there. Stretching may be performed after dyeing with iodine, or may be performed while dyeing, or may be performed with dyeing after iodine. The film can be stretched in an aqueous solution of boric acid or potassium iodide or in a water bath.

<Polarizing plate protective film>
The transparent protective film can be provided as a polymer coating layer, a film laminate layer, or the like. (Hereinafter, the coating layer is also referred to as a polarizing plate protective film.) As the transparent polymer or film material for forming the polarizing plate protective film, an appropriate transparent material can be used, but transparency, mechanical strength, heat Those excellent in stability and moisture barrier properties are preferably used. Examples of the material for forming the transparent protective film include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as cellulose diacetate and cellulose triacetate, acrylic polymers such as polymethyl methacrylate, polystyrene, acrylonitrile, Examples thereof include styrene polymers such as styrene copolymers (AS resins), polycarbonate polymers, and the like. In addition, polyethylene, polypropylene, polyolefins having a cyclo or norbornene structure, polyolefin polymers such as ethylene / propylene copolymers, vinyl chloride polymers, amide polymers such as nylon and aromatic polyamide, imide polymers, sulfone polymers , Polyethersulfone polymer, polyetheretherketone polymer, polyphenylene sulfide polymer, vinyl alcohol polymer, vinylidene chloride polymer, vinyl butyral polymer, arylate polymer, polyoxymethylene polymer, epoxy polymer, JP Examples of the polymer that forms the transparent protective film include the polymers described in Japanese Patent Application Laid-Open No. 2001-343529, or blends of the polymers. The transparent protective film can also be formed as a cured layer of thermosetting or ultraviolet curable resin such as acrylic, urethane, acrylurethane, epoxy, and silicone.

  As the transparent protective film, various polymer films described above can be used as appropriate depending on the purpose. From the viewpoints of polarization properties, durability, suitability for production, etc., a cellulose-based polymer is preferable, and triacetyl cellulose is particularly preferably used. It is done.

Although the thickness of a transparent protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable.
(Film retardation)
In the present specification, Re (λ) and Rth (λ) respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ. Re is measured with KOBRA 21ADH (manufactured by Oji Scientific Instruments Co., Ltd.) by making light of wavelength λ nm incident in the normal direction of the film. Rth was measured by making light having a wavelength λ nm incident from a direction inclined + 40 ° with respect to the normal direction of the film with the slow axis in the plane (determined by KOBRA 21ADH) as the tilt axis (rotation axis). A retardation value and a retardation value measured by making light of wavelength λ nm incident from a direction inclined by −40 ° with respect to the film normal direction with the in-plane slow axis as the tilt axis (rotation axis). KOBRA 21ADH is calculated based on the retardation value measured in the direction. Here, as the assumed value of the average refractive index, values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer. The average refractive index values of main optical films are exemplified below: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH calculates nx, ny, and nz by inputting the assumed value of the average refractive index and the film thickness. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

<Addition of optical functions>
The polarizing plate of the present invention may also serve as another optical functional layer in practical use, and may be used by being laminated. The optical functional layer is not particularly limited. For example, a liquid crystal display device such as a reflection plate, a semi-transmission plate, a phase difference plate (including a wavelength plate such as 1/2 or 1/4), a viewing angle compensation film, or the like is formed. The optical functional layer that may be used in the film may also be used as a protective film, or may be laminated in one layer or two or more layers. In addition to adding a compound that adjusts the retardation to the protective film, or depending on the material, the retardation can be imparted to the film itself by stretching the film. This can be achieved by laminating a layer having a phase difference such as a layer in which the orientation state is fixed by coating or a stretched film as described above. Various films can be used as the optical functional layer, but it is considered that the luminance unevenness in the corner portion generated by the continuous lighting of the liquid crystal display device hardly affects even if any film is used. It is speculated that the addition / stacking of components tends to slow down the sensitivity to fluctuations such as expansion and contraction, and that several factors such as the amount of expansion and contraction of the polarizer are larger than those of these members. Because.

<Other functional layers>
On the surface of the transparent protective film to which the polarizer is not adhered, the hard coat layer, antireflection layer, light diffusion or antiglare layer, antisticking, ultraviolet absorption, antistatic and antifouling functions are provided. Can be granted. These functional layers can also serve as a polarizing plate protective film, but may be provided as a separate configuration in the form of a front plate.

The hard coat layer is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a hard coating layer having an excellent hardness and slipping property with an appropriate curable resin such as acrylic or silicone is used for the transparent protective film. Those formed by a method of adding to the surface are well known. The antireflection layer is a layer in which layers having different refractive indexes are laminated to prevent reflection by interference, and can be achieved by forming an antireflection film or the like according to the prior art.
The anti-sticking layer is applied for the purpose of preventing adhesion with an adjacent layer, and the ultraviolet absorbing layer is applied for the purpose of preventing the ultraviolet rays from reaching the inside of the apparatus.

  The anti-glare (anti-glare) layer is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, a sand blasting method or an embossing method It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a surface roughening method or a blending method of transparent fine particles. The fine particles to be included in the formation of the surface fine concavo-convex structure are, for example, conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide or the like having an average particle size of 0.5 to 50 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

An adhesive is used for the adhesion treatment between the polarizer and the transparent protective film. Examples of the adhesive include isocyanate adhesives, polyvinyl alcohol adhesives, epoxy adhesives, gelatin adhesives, vinyl latexes, and water-based polyesters. As the adhesive, an adhesive made of an aqueous solution is usually used.
In particular, since an adhesive drying step after bonding is not required, a solventless active energy ray-curable composition containing an alicyclic epoxy compound (hereinafter simply referred to as “epoxy adhesive”) is used as the adhesive. "Composition" may also be used preferably. By using a solventless active energy ray-curable composition containing an alicyclic epoxy compound, it is possible to improve the durability of the polarizing plate in a harsh environment, and the step of drying the adhesive Since it is unnecessary, productivity can be improved.

  Here, the alicyclic epoxy compound means one having an epoxy group directly in the ring of the saturated cyclic compound and one having a glycidyl ether group or glycidyl group directly in the ring of the saturated cyclic compound. In addition, you may have another epoxy group in the structure.

  The alicyclic epoxy compound having an epoxy group directly on the ring of the saturated cyclic compound can be obtained, for example, by the method described in paragraphs 0074 to 0081 of JP 2010-091603 A.

  Specific examples of the alicyclic epoxy compound having an epoxy group directly on the ring of the saturated cyclic compound preferably used in the present invention include, for example, 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate, 1,2-epoxy-4-vinylcyclohexane, 1,2-epoxy-1-methyl-4- (1-methylepoxyethyl) cyclohexane, 3,4-epoxycyclohexylmethyl methacrylate, 2,2-bis (hydroxymethyl) ) -1-Butanol 4- (1,2-epoxyethyl) -1,2-epoxycyclohexane adduct, ethylene bis (3,4-epoxycyclohexanecarboxylate), oxydiethylene bis (3,4-epoxycyclohexanecarboxy) Rate), 1,4-cyclohe Dimethyl bis (3,4-epoxycyclohexane carboxylate), and 3- (3,4-epoxycyclohexyl-methoxycarbonyl) propyl 3,4-epoxycyclohexane carboxylate and the like.

  An alicyclic epoxy compound having a glycidyl ether group or a glycidyl group directly on the ring of the saturated cyclic compound can be obtained by the method described in paragraphs 0083 to 0086 of JP2010-091603A, for example.

  Among the alicyclic epoxy compounds described above, 3,4-epoxy has good cured product characteristics in improving the durability of the polarizing plate, or has moderate curability and is available at a relatively low price. A hydrogenated product of cyclohexylmethyl 3,4-epoxycyclohexanecarboxylate and a glycidyl etherified product of bisphenol A is preferred, and 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate is more preferred.

  These alicyclic epoxy compounds may be used alone or in combination of two or more.

  Such alicyclic epoxy compounds can be easily obtained as commercial products. For example, “Celoxide”, “Cyclomer” (manufactured by Daicel Chemical Industries, Ltd.) and “ "Syra cure" (made by Dow Chemical Co.).

In this invention, active energy ray-curable compounds other than an alicyclic epoxy compound can be mix | blended with an epoxy-type adhesive composition. As such an active energy ray-curable compound, an epoxy compound other than the alicyclic epoxy compound can be used. By using together an epoxy compound other than such an alicyclic epoxy compound, the adhesion between the polarizer and the transparent protective film can be improved.
Epoxy compounds other than such alicyclic epoxy compounds, oligomers thereof, and the like can be easily obtained from commercial products. For example, “Epicoat” (manufactured by Japan Epoxy Resin Co., Ltd.) under the trade name. , "Epiclon" (manufactured by DIC Corporation), "Epototo" (manufactured by Toto Kasei Co., Ltd.), "Adeka Resin" (manufactured by ADEKA Corporation), "Denacol" (manufactured by Nagase ChemteX Corporation), "Dow Epoxy" (Dow Chemical) And “Tepic” (manufactured by Nissan Chemical Industries, Ltd.).

  The epoxy equivalent of the alicyclic epoxy compound and the epoxy compound other than the alicyclic epoxy compound used in the present invention is usually 30 to 2000 g / eq, preferably 50 to 1500 g / eq, and preferably 70 to 1000 g / eq. More preferably, it is eq. This epoxy equivalent is a value measured according to JIS K 7236 (ISO 3001). If the epoxy compound is a high purity monomer, the theoretical amount can be calculated from the molecular weight.

  Moreover, an oxetane compound can also be used as the active energy ray-curable compound. By using the oxetane compound in combination, the curing rate of the active energy ray-curable composition can be improved. The oxetane compound is a compound having an oxetane ring and is not particularly limited as long as it is active energy ray curable. For example, 1,4-bis {[(3-ethyloxetane-3-yl) Methoxy] methyl} benzene, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane, bis (3-ethyl-3-oxetanylmethyl) ether, 3-ethyl-3- (phenoxymethyl) oxetane, 3-ethyl -3- (cyclohexyloxymethyl) oxetane, phenol novolac oxetane, 1,3-bis [(3-ethyloxetane-3-yl) methoxy] benzene, and the like.

  Such oxetane compounds can be easily obtained as commercial products. For example, “Aron Oxetane” (manufactured by Toagosei Co., Ltd.) and “ETERRNACOLL” (manufactured by Ube Industries, Ltd.) are available under the trade names. Etc.

  The compounding ratio of the alicyclic epoxy compound in the active energy ray curable composition is a total of 100 parts by weight of the active energy ray curable compound (alicyclic epoxy compound, epoxy compound other than the alicyclic epoxy compound and oxetane compound). The alicyclic epoxy compound is preferably 30 to 95 parts by weight, more preferably 50 to 90 parts by weight, and still more preferably 70 to 85 parts by weight.

  The total chlorine content contained in the active energy ray-curable composition containing the alicyclic epoxy compound used in the present invention is preferably in the range of 0.1 ppm to 15000 ppm, more preferably in the range of 0.5 ppm to 2000 ppm. A range of 0.0 to 1000 ppm is more preferable. This total chlorine amount is a value measured in accordance with JIS K 7243-3 (ISO 21627-3).

  The hue of the active energy ray-curable composition containing the alicyclic epoxy compound used in the present invention is preferably 5 or less, more preferably 3 or less in terms of Gardner chromaticity of the active energy ray-curable composition before curing. The following is more preferable.

  The active energy ray-curable composition containing an alicyclic epoxy compound used in the present invention is hardened (cured) by irradiation with active energy rays, and provides curability that gives an adhesive force between the films sandwiching the cured product layer. It is a composition.

  Examples of the active energy ray used include X-rays having a wavelength of 1 pm to 10 nm, ultraviolet rays having a wavelength of 10 to 400 nm, and visible rays having a wavelength of 400 to 800 nm. Among these, ultraviolet rays are preferably used in terms of ease of use, ease of adjustment of the active energy ray-curable composition and its stability, and its curing performance.

  Although the light source to be used is not particularly limited, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, having a light emission distribution at a wavelength of 400 nm or less, And metal halide lamps.

The irradiation intensity is determined by the active energy ray-curable composition and the irradiation time, and is not particularly limited. For example, the irradiation intensity in the wavelength region effective for activating the initiator is 0.1. It is preferable that it is -1000mW / cm < ² >.

The irradiation time is determined by the active energy ray-curable composition and the irradiation intensity and is not particularly limited. For example, the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is 10 to 5 It is preferably set to be 000 mJ / cm ² .

  The active energy ray-curable composition containing an alicyclic epoxy compound used in the present invention preferably contains a cationic polymerization initiator in order to be cured by active energy rays.

  These cationic polymerization initiators may be used alone or in combination of two or more. Among them, aromatic sulfonium salts are particularly preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and therefore can provide a cured layer having excellent curability and good mechanical strength and adhesive strength. .

  The compounding quantity of a cationic polymerization initiator is 0.5-20 weight part normally with respect to a total of 100 weight part of an active energy ray hardening compound, and 1-15 weight part is preferable.

  These cationic polymerization initiators can be easily obtained from commercial products, for example, “Kayarad” (manufactured by Nippon Kayaku Co., Ltd.), “Syracure” (manufactured by Union Carbide), Photoacid generator “CPI” (manufactured by San Apro Co., Ltd.), photoacid generators “TAZ”, “BBI”, “DTS” (manufactured by Midori Chemical Co., Ltd.), “Adekaoptomer” (manufactured by ADEKA Corporation) And “RHODORSIL” (manufactured by Rhodia).

  The active energy ray-curable composition containing the alicyclic epoxy compound used in the present invention can be used in combination with a photosensitizer as necessary. By using a photosensitizer, the reactivity is improved, and the mechanical strength and adhesive strength of the cured product layer can be improved.

  The photosensitizer is not particularly limited, and examples thereof include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes. .

  The photosensitizers may be used alone or in combination. The photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight when the active energy ray-curable composition is 100 parts by weight.

  Various additives can be blended with the active energy ray-curable composition used in the present invention as long as the effects of the present invention are not impaired. Examples of various additives include ion trapping agents, antioxidants, chain transfer agents, sensitizers, tackifiers, thermoplastic resins, fillers, flow regulators, plasticizers, and antifoaming agents. It is done.

  The polarizing plate is produced by bonding the transparent protective film and the polarizer using the adhesive. The adhesive may be applied to either the transparent protective film or the polarizer, or to both. After the bonding, a drying process is performed to form an adhesive layer composed of a coating dry layer. Bonding of a polarizer and a transparent protective film can be performed with a roll laminator or the like. The thickness of the adhesive layer is not particularly limited, but is usually about 0.1 to 5 μm.

<Adhesive layer>
The above-mentioned polarizing plate and the optical member having at least one polarizing plate are provided with an adhesive layer for bonding with the liquid crystal cell. An adhesive layer can also be provided for bonding with other members other than the liquid crystal cell. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, a silicone-based polymer, a polyester, a polyurethane, a polyamide, a polyether, a fluorine-based or rubber-based polymer is appropriately used as a base polymer. It can be selected and used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability of liquid crystal display devices with high quality and excellent durability An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.
Further, from the viewpoint of workability (reworkability) of fixing and bonding of the polarizing plate, the adhesive strength of the pressure-sensitive adhesive layer is preferably 1 N / 25 mm or more, and more preferably 5 N / 25 mm or more. The upper limit is not particularly limited.

  The storage elastic modulus (G ′) of the pressure-sensitive adhesive at 23 ° C. is preferably 20 to 100 in order to suppress the follow-up of the polarizing plate and the liquid crystal cell to the expansion and contraction and the propagation of the stress of the member sandwiching the pressure-sensitive adhesive layer. -70 [MPa] is more preferable.

  The pressure-sensitive adhesive layer is, for example, a natural or synthetic resin, in particular, a tackifier resin, a filler, a pigment, a colorant, an antioxidant made of glass fiber, glass beads, metal powder, or other inorganic powders. It may contain an additive to be added to the adhesive layer. Moreover, the adhesive layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  The pressure-sensitive adhesive layer can be provided on one side or both sides of a polarizing plate or an optical member as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as adhesive layers, such as a different composition, a kind, and thickness, in the front and back of a polarizing plate or an optical member. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 500 μm, preferably 5 to 200 μm, and particularly preferably 10 to 100 μm.

  A separator is temporarily attached to the exposed surface of the pressure-sensitive adhesive layer for the purpose of preventing contamination until it is put into practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate conventional ones such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based, or molybdenum sulfide can be used.

  In the present invention, the above polarizing plate, optical member, etc., and each layer such as an adhesive layer, for example, salicylic acid ester compounds, benzophenol compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds It is also possible to use one having a UV-absorbing ability by a method such as a method of treating with a UV absorber.

  Attaching the adhesive layer to one side or both sides of the polarizing plate or the optical member can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by mass in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of an appropriate solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method in which it is directly attached on a polarizing plate or an optical member by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on a separator in accordance with the above, and this is applied to a polarizing plate or optical A method of transferring onto the member is exemplified.

<Plateing of polarizing plate>
The pressure-sensitive adhesive layer attached in this manner is bonded to the polarizing plate, the liquid crystal cell, and other functional members.
When producing the liquid crystal display device of the present invention, the water content of the polarizing plate when the polarizing plate is bonded to the liquid crystal cell is determined by the equilibrium water content of the polarizing plate at 25 ° C. 30% RH to 25 ° C. 50% RH. The liquid crystal display device satisfying the above formulas (I) and (II) (preferably satisfying the above formulas (I ′) and (II ′)) can be manufactured by adjusting the ratio to be a ratio. More preferably, the equilibrium water content is adjusted to an equilibrium water content of 25 ° C. and 30% RH to 25 ° C. and 45% RH, and more preferably adjusted to an equilibrium water content of 25 ° C. and 35% RH to 25 ° C. and 45% RH. It is to be.
Here, the equilibrium moisture content is the moisture content in a state where the amount of moisture in the material has reached equilibrium in the atmosphere under a constant temperature and humidity environment. It depends on the material that is composed. As a method for adjusting the equilibrium moisture content, according to the definition, the equilibrium moisture content can be adjusted by leaving the object in a controlled target atmosphere until it reaches an equilibrium state.

<Liquid crystal display device>
There are no particular restrictions on the mode of the liquid crystal display device, and TN (Twisted Nematic), IPS (In-Plane Switching Crystal), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Crystal), OCBlColST, OCB1 (OCB1). (Super Twisted Nematic), VA (Vertically Aligned), and HAN (Hybrid Aligned Nematic) liquid crystal display devices of any display mode, such as the difference in size between the polarizing plate layer and the adhesive layer, the attachment to the liquid crystal cell By adjusting the moisture content of the polarizing plate at the time, a luminance unevenness reducing effect can be obtained.

  As the light source, a direct type backlight using a CCFL (Cold Cathode Fluorescent Lamp) or LED (Light Emitting Diode) as a light source, a sidelight type backlight, or a light source using a planar light source can be used. In addition, a member such as a reflector or a brightness enhancement film can be used for the backlight in order to increase the light use efficiency. Furthermore, when forming the liquid crystal display device, components such as a diffusion plate, a protective plate, a prism array, a lens array sheet, and a light diffusion plate can be appropriately disposed in one layer or two or more layers in addition to the above-described members.

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

(Measurement method of dimensions of polarizing plate and adhesive layer)
The dimension P of the polarizing plate is measured by bonding the polarizing plate to the liquid crystal cell with an adhesive layer and leaving it in a 25 ° C. 60% RH environment for one week, and then measuring the dimension in the direction parallel to the absorption axis of the polarizing plate ( _PMD ) And the dimension (P _TD ) in the direction orthogonal to the absorption axis was measured using a metal ruler used for general length measurement. The dimension N of the pressure-sensitive adhesive layer is measured by observing the side portion of the polarizing plate bonded to the liquid crystal cell with a reflection optical microscope and calculating the length δ of the portion where the polarizing plate floats from the liquid crystal cell and appears white. (See FIG. 1). Here, when δ on two opposite sides of the polarizing plate is δ1 and δ2, respectively, the dimension N of the pressure-sensitive adhesive layer is represented by the following formula.
N = P− (δ1 + δ2)
N (N _MD , N _TD ) can be determined from the above formulas in a direction parallel to the absorption axis of the polarizing plate and a direction orthogonal to the absorption axis.

(Preparation of film 1)
A commercially available triacetylcellulose film (“TD80” manufactured by Fuji Film Co., Ltd., thickness 80 μm) was prepared. This was used as film 1.

(Preparation of film 2)
The following composition was put into a mixing tank and stirred while heating to dissolve each component to prepare a cellulose acetate solution.
Cellulose acetate (substitution degree 2.86) 100.0 parts by mass Polyester diol * 1 10 parts by mass Solvent (composition is described below) 462 parts by mass * 1: Consisting of adipic acid and ethylene glycol, hydroxyl value 113 polyester diol.
The solvent composition was as follows.
Methylene chloride (first solvent) 100 parts by weight Methanol (second solvent) 19 parts by weight 1-butanol 1 part by weight

The following composition was charged into a disperser and stirred to dissolve each component to prepare a matting agent dispersion. 1.3 parts by mass of this matting agent dispersion was added to the cellulose acetate solution to prepare a dope.
Composition of matting agent dispersion:
Silica particle dispersion (average particle size 16 nm) 10.0 parts by mass (“AEROSIL R972”, manufactured by Nippon Aerosil Co., Ltd.)
-Methylene chloride 72.8 parts by mass-Methanol 3.9 parts by mass-Butanol 0.5 parts by mass-Cellulose acetate solution * 1 10.3 parts by mass * 1: In preparation of the cellulose acylate solution, adipic acid and ethylene glycol The cellulose acylate solution was prepared in the same manner except that 20 parts by mass of a polyester diol having a hydroxyl value of 156 was added to 100 parts by mass of cellulose acetate (substitution degree 2.86).

  The prepared dope was cast from a casting port onto a drum cooled to -5 ° C. The film is peeled off in a state where the solvent content is approximately 70% by mass, and both ends in the width direction of the film are fixed with a pin tenter (a pin tenter described in FIG. 3 of JP-A-4-1009), and the solvent content is 3-5% by mass. In this state, the film was dried while maintaining an interval at which the stretch ratio in the width direction (direction perpendicular to the machine direction) was about 3%. Then, by conveying between the rolls of the heat treatment apparatus, it was further dried to produce a cellulose acylate film having a thickness of about 60 μm. This was used as film 2.

(Preparation of film 3)
(Dissolution)
Cellulose acylate (cellulose triacetate with a substitution degree of 2.87), plasticizer (mixture of triphenyl phosphate (TPP) and biphenyl diphenyl phosphate (BDP) (TPP / BDP (ratio to 100 parts by mass of cellulose acylate)) = 7.8 parts by mass / 3.9 parts by mass)), the following retardation developer (1) (0.71 parts by mass with respect to 100 parts by mass of cellulose acylate), and the following compound A (100 parts by mass of cellulose acylate) 1.4 parts by mass) is added to the following mixed solvent, dichloromethane / methanol / butanol (82/15/3 parts by mass) with stirring so that the mass concentration of cellulose acylate is 18% by mass, and heated. Stir to dissolve. At the same time, 0.05 part by mass of a matting agent (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.), which is fine particles, was added to 100 parts by mass of cellulose acylate and stirred while heating.

(Casting)
The dope was cast from a casting port onto a drum cooled to 0 ° C. The film is peeled off in a state where the solvent content is 70% by mass, and both ends in the width direction of the film are fixed with a pin tenter (the pin tenter described in FIG. 3 of JP-A-4-1009), and the solvent content is 3 to 5% by mass. In this state, the film was dried while maintaining an interval at which the stretching ratio in the width direction (direction perpendicular to the machine direction) was 3%. Then, it dried further by conveying between the rolls of a heat processing apparatus, both ends were cut off in front of the winding part, and it wound up as film 3 (80 micrometers in thickness).

(Preparation of film 4)
Cellulose acylate having a degree of acetyl group substitution of 2.81, plasticizer (mixture of triphenyl phosphate (TPP) and biphenyl diphenyl phosphate (BDP) (TPP / BDP (ratio to 100 parts by mass of cellulose acylate)) = 7 8 parts by mass / 3.9 parts by mass)), and the following retardation developer (2) (6.4 parts by mass with respect to 100 parts by mass of cellulose acylate) in dichloromethane / methanol (87/13 parts by mass). The cellulose acylate was stirred while being stirred so that the mass concentration of the cellulose acylate was 15% by mass, and dissolved by heating and stirring. At the same time, 0.05 part by mass of a matting agent (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) as fine particles and 0.0009 part by mass of the following dye (1) are added to 100 parts by mass of cellulose acylate. Stir while heating.

(Casting)
The above dope was cast using a band casting machine. A film peeled off from the band with a residual solvent amount of 25 to 35% by mass, in the longitudinal direction at a stretch ratio of 3% in the section from stripping to tenter, under the condition where the stretching temperature is in the range of about Tg-5 to Tg + 5 ° C. Then, using a tenter, the film was stretched in the width direction at a stretch ratio of 32%, and immediately after transverse stretching, the film was removed from the tenter after shrinking in the width direction at a ratio of 7% to produce a cellulose acylate film. Filmed. Both ends were cut off in front of the winding part to make a width of 2000 mm and wound up as a roll film having a length of 4000 m. This was used as film 4 (thickness 82 μm).

(Preparation of film 5)
A film having a film thickness of 140 μm made of “ZEONOR 1420 R” {manufactured by Nippon Zeon Co., Ltd.} is longitudinally stretched at a supply rate of 140 ° C., a film surface temperature of 130 ° C. and a draw ratio of 30% in a longitudinal uniaxial stretching machine. Stretched. Then, in a tenter stretching machine, the film is stretched horizontally at an air supply temperature of 140 ° C. and a film film surface temperature of 130 ° C. at a stretching ratio of 40%. I took it. A biaxially stretched film was used as film 5. The thickness of the obtained film was 105 μm.

(Preparation of film 6)
A film was prepared in the same manner except that the stretching ratio in the width direction was set to 39%, and this was used as film 6 (thickness 78 μm).

(Preparation of film 7)
The inner layer and outer layer dopes having the following compositions were respectively prepared.
Composition of inner layer dope:
Cellulose acetate C-1 100 parts by mass (acetyl substitution degree 2.81, number average molecular weight 88000)
The retardation developer (2) 7 parts by mass The following polymer P-2 9.0 parts by mass The dye (1) (Bluing dye) 0.000078 parts by mass Dichloromethane 423.9 parts by mass Methanol 63.3 parts by mass

Composition of outer layer dope:
Cellulose acetate C-1 100 parts by mass (acetyl substitution degree 2.81, number average molecular weight 88000)
The retardation developer (2) 7 parts by mass The following polymer P-2 9.0 parts by mass The dye (1) (Bluing dye) 0.000078 parts by mass Silica particles having an average particle size of 16 nm 0.14 parts by mass ("AEROSIL R972" manufactured by Nippon Aerosil Co., Ltd.)
Dichloromethane 424.5 parts by mass Methanol 63.4 parts by mass

Polymer P-2: polycondensation comprising a dicarboxylic acid residue of TPA / PA / SA / AA (= 45/5/30/20 (mol%)) and a diol residue of ethylene glycol (100 mol%) A polycondensate having both ends sealed with acetyl ester residues and having a number average molecular weight of 900 (where TPA is terephthalic acid, PA is phthalic acid, SA is sebacic acid, AA is adipine) Acid.)

  The outer layer and inner layer dope solutions having the above composition are uniformly and simultaneously laminated on a stainless steel band support with a width of 2000 mm so as to form a three-layer structure of an outer layer on the support surface side, an inner layer, and an outer layer on the air interface side using a band casting apparatus. Casted. With the stainless steel band support, the solvent was evaporated until the residual solvent amount was 40% by mass, and the stainless steel band support was peeled off. Stretching is applied to stretch so that the longitudinal (MD) stretch ratio is 1.02, then both ends are held by a tenter, and the stretch ratio in the width (TD) direction is 1.22 times. Thus, the film was stretched in the transverse direction (lateral stretching) at a rate of 45% / min. The residual solvent amount at the start of stretching was 30% by mass. It was made to dry for 35 minutes in a 115 degreeC drying zone, conveying after extending | stretching. After drying, it was slit to a width of 1340 mm, and a cellulose acylate film having a thickness of 78 μm and a thickness ratio of each layer of the support surface side outer layer: inner layer: air interface side outer layer = 3: 94: 3 was obtained. This was used as film 7.

(Preparation of film 8)
(Preparation of Cellulose Acylate Solution C01 for Low Substitution Degree Layer) Inner Layer Formulation The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution. The amount of the solvent (methylene chloride and methanol) was appropriately adjusted so that the solid content concentration of each cellulose acylate solution was 22% by mass.
Cellulose acetate (substitution degree 2.45) 100.0 parts by mass Compound B 19.0 parts by mass Methylene chloride 365.5 parts by mass Methanol 54.6 parts by mass The above compound B is terephthalic acid / succinic acid / propylene chloride Represents a recall / ethylene glycol copolymer (copolymerization ratio [mol%] = 27.5 / 22.5 / 25/25), both ends are sealed with acetyl ester residues, and the number average molecular weight is 900 It is a polycondensate of

(Preparation of Cellulose Acylate Solution S01 for High Substitution Level Layer) Outer Layer Formulation The following composition was put into a mixing tank and stirred to dissolve each component to prepare a cellulose acylate solution. The amount of the solvent (methylene chloride and methanol) was appropriately adjusted so that the solid content concentration of each cellulose acylate solution was 19.7 (mass%).
-Cellulose acetate (substitution degree 2.79) 100.0 parts by mass-Compound B 11.0 parts by mass-Silica fine particles R972 (manufactured by Nippon Aerosil Co., Ltd.) 0.15 parts by mass-Methylene chloride 395.0 parts by mass-Methanol 59. 0 parts by mass

(Creation of cellulose acylate sample)
The cellulose acylate solution for the low substitution layer was cast to be an inner layer having a film thickness of 56 μm, and the cellulose acylate solution for the high substitution layer was cast to be an outer layer A and an outer layer B having a film thickness of 2 μm. . The obtained web (film) was peeled off from the band, sandwiched between clips, and a tenter was used at a stretching temperature of 140 ° C. and a stretching ratio of 1.08 times when the residual solvent amount relative to the total mass of the film was 20 to 5%. And stretched laterally.
Thereafter, the clip was removed from the film and dried at 130 ° C. for 20 minutes, and then stretched again using a tenter at a stretching temperature of 180 ° C. and a stretching ratio of 1.20 times.
The residual solvent amount was determined according to the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
Here, M is a mass of the web at an arbitrary time point, and N is a mass when the web of which M is measured is dried at 120 ° C. for 2 hours.
The cellulose acylate film thus obtained was used as a film 8 (thickness 60 μm).

(Preparation of film 9)
-Preparation of fine particle dispersion The following components were stirred and mixed to prepare a fine particle dispersion.
Fine particles (R972V (produced by Nippon Aerosil Co., Ltd.)) 11 parts by mass Ethanol 89 parts by mass

・ Preparation of fine particle additive solution Cellulose acylate was added to the dissolution tank containing methylene chloride at the following ratio, and heated to completely dissolve, then, this was added to Azumi Filter Paper No. Filtered using 244. While sufficiently stirring the filtered cellulose acylate solution, the fine particle dispersion prepared above was slowly added thereto at the following ratio. Further, dispersion was performed with an attritor. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution.
Methylene chloride 99 parts by weight Cellulose acylate (see Table 1 below) 4 parts by weight Fine particle dispersion 11 parts by weight

-Preparation of main dope The main dope liquid of the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acylate was charged into a pressurized dissolution tank containing a solvent while stirring. This was heated, stirred and completely dissolved, and the plasticizer and ultraviolet absorber shown in Table 1 below were added and dissolved. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.
<Composition of main dope solution>
Methylene chloride 300 parts by mass Ethanol 60 parts by mass Cellulose acylate (see Table 1 below) 73 parts by mass additive (compounds see Table 1) Table 1

(Casting)
100 parts by mass of the main dope solution and 2 parts by mass of the fine particle additive solution are sufficiently mixed with an in-line mixer (Toray's static in-pipe mixer Hi-Mixer, SVII) to prepare a dope, which is a belt casting apparatus. Was uniformly cast on a stainless steel band support having a width of 2 m. On the stainless steel band support, the solvent was evaporated until the residual solvent amount became 110%, and the stainless steel band support was peeled off. Tension was applied during the peeling to stretch the longitudinal (MD) stretch ratio to 1.0, and then both ends of the web were gripped with a tenter, the residual solvent amount at the start of stretching was 20% by mass, and the temperature was 130. It extended | stretched so that the draw ratio of the width | variety (TD) direction might be 1.3 times at ° C. After stretching, hold for several seconds while maintaining its width, release the width holding after relaxing the tension in the width direction, further carry for 30 minutes in the third drying zone set at 125 ° C., and perform drying, A cellulose acylate film having a width of 1.5 m, a knurling having a width of 1 cm at the end and a height of 8 μm was produced. This was used as a film 9 (thickness 43 μm).

* 1: Acetyl group substitution degree * 2: Propionyl group substitution degree * 3: (a) is a commercial product of a single oligomer of methyl acrylate (average molecular weight 1000); (b) is in the [0058] column of WO 2007/125664 Compound 3 as described.
* 4: Stretch ratio in the width direction perpendicular to the casting direction

(Preparation of film 10)
“Zeonor 1420 R” {manufactured by Nippon Zeon Co., Ltd., thickness 100 μm} was longitudinally stretched at a supply temperature of 140 ° C. and a film film surface temperature of 130 ° C. at a stretching ratio of 30% in a longitudinal uniaxial stretching machine. Then, in a tenter stretching machine, the film is stretched horizontally at an air supply temperature of 140 ° C. and a film film surface temperature of 130 ° C. at a stretching ratio of 40%. I took it. A biaxially stretched film was used as the film 10. The thickness of the obtained film was 60 μm.

(Film physical properties)
The film thicknesses, Re (in-plane retardation) and Rth (thickness direction retardation) of the films 1 to 10 were as shown in Table 2 below. Re and Rth were measured using KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).

(Preparation of polarizing plate)
1. Surface treatment Films 1 to 4 and 6 to 9 were subjected to the following alkali saponification treatment and then used for production of polarizing plates. Moreover, about the films 5 and 10, after performing the following corona treatment, it used for preparation of a polarizing plate.

Alkali saponification treatment:
Each film was immersed in a 1.5 mol / L NaOH aqueous solution (saponification solution) maintained at 55 ° C. for 2 minutes, then washed with water, and then immersed in a 0.05 mol / L sulfuric acid aqueous solution at 25 ° C. for 30 seconds. did. Thereafter, a water bath was further passed under running water for 30 seconds to make the film neutral. Then, draining with an air knife was repeated three times, and after dropping the water, it was retained in a drying zone at 70 ° C. for 15 seconds and dried. In this manner, each film was subjected to saponification treatment.

Corona treatment:
A surface of the film to be bonded to the polarizer was subjected to corona discharge treatment using a high-frequency oscillator to obtain a film having a surface tension of 0.055 N / m.

2. Production of Polarizing Plate 2-1 Production of Polarizing Plate 1 to 10 Production of Polarizer:
According to Example 1 of Unexamined-Japanese-Patent No. 2001-141926, the 20-micrometer-thick polarizer was produced by making iodine adsorb | suck to the stretched polyvinyl alcohol film.

  Using a polyvinyl alcohol-based adhesive, attach a commercially available triacetyl cellulose film (“TD80” manufactured by Fuji Film Co., Ltd.) on one side of the polarizer and films 1 to 10 on the other side, and dry at 70 ° C. for 10 minutes or more. Polarizing plates 1 to 10 were obtained. A pressure-sensitive adhesive was applied to the surface of the polarizing plate on which the films 1 to 10 were bonded, and a pressure-sensitive adhesive layer was provided with a thickness of 20 μm.

Production of Polarizing Plate 2-2 Production of Polarizing Plate 11 to 20 Production of Polarizer:
Instead of the polyvinyl alcohol adhesive, the following epoxy adhesive composition was used, and a commercially available triacetyl cellulose film (“TD80” manufactured by Fuji Film) was used on one side of the polarizer, and films 1 to 10 on the other side. Is bonded with a bonding roll, and then the adhesive composition is cured by irradiating the metal halide lamp from the triacetylcellulose film side so that the integrated light quantity at a wavelength of 320 to 400 nm is 600 mJ / cm ^2. Plates 11-20 were obtained. A pressure-sensitive adhesive was applied to the surface of the polarizing plate on which the films 1 to 10 were bonded, and a pressure-sensitive adhesive layer was provided with a thickness of 20 μm.
(Epoxy adhesive composition)
3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate 40 parts by mass Bisphenol A type epoxy resin 60 parts by mass diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate (cationic polymerization initiator) 4.0 mass Part benzoin methyl ether (photosensitizer) 1.0 part by mass

  The epoxy equivalent of 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate was 126 g / eq, and the epoxy equivalent of bisphenol A type epoxy resin was 187 g / eq. Moreover, the total chlorine content of the epoxy adhesive composition was 840 ppm, and the viscosity measured at 60 rpm with a B-type viscometer at 25 ° C. was 3000 mPa · s. The total chlorine content of the epoxy adhesive composition was measured by a titration method using a silver nitrate solution in accordance with JIS K 7243-3 (ISO 21627-3).

3. Production of liquid crystal display device:
The polarizing plate attached to the liquid crystal cell of the commercially available liquid crystal display device is peeled off, and the polarizing plates 1 to 10 are bonded to the viewing side of the liquid crystal cell and the backlight (BL) side through an adhesive layer according to Table 3 below. Examples 1 to 18 and Comparative Examples 19 to 23 were produced. Here, before bonding, each polarizing plate was allowed to have an equilibrium water content at the humidity (humidity at 25 ° C.) shown in Table 3 below.
As the liquid crystal display device, a VA mode and an IPS mode were prepared. As the VA mode liquid crystal display device, BenQ XT4242 (42 inch LED backlight, edge light type, cell clearance 1 mm, the BL side of the liquid crystal cell has high sealing properties) is used. Similarly, a 42-inch LED backlight type liquid crystal display device was used as the IPS mode liquid crystal display device. (Cell clearance is 1mm. The BL side of the liquid crystal cell has high sealing performance)

(Evaluation)
The prepared liquid crystal display devices of Examples 1 to 18 and Comparative Examples 19 to 23 were continuously lit, and luminance unevenness in black display at the time of lighting for 1 hour was observed from the front with a distance of 1.5 m. Light leakage occurring at the four corners was evaluated according to the following criteria and summarized in Table 3 above.
◎: Light leakage at the four corners is weak and no problem ○: Light leakage at the four corners is within the allowable range ×: Light leakage at the four corners is not allowed
XX: Strong light leakage at the four corners

When the above-described evaluation was also conducted on a 32-inch and 65-inch VA mode liquid crystal display device having a backlight structure similar to XT4242, the same results as XT4242 were obtained.
As for the IPS mode liquid crystal display device, an experiment was conducted on 32 inch and 65 inch IPS mode liquid crystal display devices, and the same result as 42 inch was obtained.
From the above, it was found that the effects of the present invention can be obtained regardless of the screen size.
Furthermore, it is the same as that of the liquid crystal display device of Examples 1-18 except having changed and bonded the polarizing plates 11-20 which changed the adhesive agent into the epoxy adhesive composition as mentioned above to the polarizing plates 1-10. Evaluation results similar to those of Examples 1 to 18 were obtained for liquid crystal display devices manufactured by various methods.

Claims (3)

A liquid crystal display device having a liquid crystal cell, a pair of polarizing plates disposed on both sides of the liquid crystal cell via an adhesive layer, and a backlight, wherein at least one of the pair of polarizing plates and the polarizing plate A liquid crystal display device characterized in that the pressure-sensitive adhesive layer in contact with satisfies the following formulas (I) and (II) in an environment of 25 ° C. and 60% RH.
(I) 0.99856 ≦ N _MD / P _MD ≦ 0.99952
(II) 0.9970 ≦ N _TD / P _TD ≦ 0.9990
(Here, N _MD is the length of the portion where the pressure-sensitive adhesive layer in the absorption axis parallel to the direction of the polarizing plate is in contact with the liquid crystal cell, P _MD is a direction parallel to the absorption axis of the polarizing plate N _TD is the length of the portion where the pressure-sensitive adhesive layer is in contact with the liquid crystal cell in the direction perpendicular to the absorption axis of the polarizing plate, and P _TD is the polarization length of the polarizing plate. (This is the length of the polarizing plate in the direction perpendicular to the absorption axis of the plate.)   The viewing-side polarizing plate of the liquid crystal display device and the adhesive layer in contact with the viewing-side polarizing plate of the pair of polarizing plates satisfy the formulas (I) and (II). Liquid crystal display device.   The pressure-sensitive adhesive layer in contact with at least one of the pair of polarizing plates and the polarizing plate satisfies the following formulas (I ′) and (II ′) in an environment of 25 ° C. and 60% RH. Liquid crystal display device.
(I ′) 0.9988 ≦ N _MD / P _MD ≤ 0.99928
(II ′) 0.9975 ≦ N _TD / P _TD ≤ 0.9985
(Where N _MD Is the length of the part where the adhesive layer is in contact with the liquid crystal cell in the direction parallel to the absorption axis of the polarizing plate, and P _MD Is the length of the polarizing plate in a direction parallel to the absorption axis of the polarizing plate. N _TD Is the length of the part where the adhesive layer is in contact with the liquid crystal cell in the direction perpendicular to the absorption axis of the polarizing plate, and P _TD Is the length of the polarizing plate in the direction perpendicular to the absorption axis of the polarizing plate. )

Images