TWI408426B - Laminated optical film and manufacturing method thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a laminated optical film capable of preventing a foreign matter from infiltrating in between a polarizer and an optical compensation film and having high transparency and high degree of polarization, and to provide a manufacturing method for the film. <P>SOLUTION: This laminated optical film is long and is provided with the long polarizer having an absorption axis in the longitudinal direction, the long optical compensation film provided with an ellipsoid, having a refractive index satisfying the relation: nx&gt;ny&ge;nz, and an optical compensation layer, provided with an ellipsoid having a refractive index, satisfying the relation: nx=ny&gt;nz by arranging them, in this order. The angle formed by the lag phase axis of the optical compensation film and the absorption axis of the polarizer is in the range of 5-85&deg;. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

Laminated optical film and method of manufacturing same

The present invention relates to a laminated optical film and a method of manufacturing the same. More specifically, the present invention relates to a laminated optical film for use in an image display device such as a liquid crystal display device and a method of manufacturing the same.

In the liquid crystal display device, it is indispensable to arrange a polarizing element on both sides of a glass substrate on the surface of the liquid crystal panel due to its image forming method. Further, in order to compensate optically of the liquid crystal panel, the optical compensation film is also disposed between the polarizing element and the glass substrate. Therefore, a laminated optical film in which a polarizing element and an optical compensation film are laminated in advance is used. In addition, a laminated optical film having an (ellipsoidal) circular polarization function in which the absorption axis of the polarizing element and the slow axis of the optical compensation film form a specific angle in the in-plane direction to increase the brightness of the liquid crystal panel is used. So-called (elliptical) circular polarizing plates, etc.

When the (elliptical) circularly polarizing plate is produced, for example, the polarizing element and the optical compensation film are arranged and cut by a specific angle between the absorption axis of the polarizing element and the slow axis of the optical compensation film, respectively. ,fit. However, since the polarizing element itself has no stickiness, there is a problem that the bonding of the polarizing element and the optical compensation film cannot be easily performed. Therefore, for example, a protective film formed of a transparent resin film or the like is bonded to both surfaces of the polarizing element to form a laminate (so-called polarizing plate), and the polarizing element is bonded to the optical compensation film (see, for example, Patent Document 1). In this case, there are a step of cutting or punching a polarizing element (polarizing plate) and an optical compensation film into a specific shape, a step of bonding the polarizing element and the protective film, and laminating (bonding) the optical body on the polarizing plate. In the step of compensating for the film, the possibility that foreign matter is mixed between the layers increases. Therefore, there is a problem that foreign matter is mixed to cause defects, or the transmittance and the degree of polarization are deteriorated.

[Patent Document 1] Japanese Patent Laid-Open Publication No. 2005-140980

The present invention has been made to solve the above problems, and a main object of the present invention is to provide a laminated optical film which is capable of preventing foreign matter from entering between a polarizing element and an optical compensation film and having excellent transmittance and polarization.

The laminated optical film of the present invention has a long optical retardation film having a relationship of a length of nx>ny≧nz and a refractive index ellipsoid which are elongated and have an absorption axis in the longitudinal direction, and an index ellipsoid having a relationship of nx>ny≧nz. The ball has an optical compensation layer in a relationship of nx=ny>nz, and the slow axis of the optical compensation film forms an angle of 5 to 85° with the absorption axis of the polarizing element.

In a preferred embodiment, the optical compensation film has an Nz coefficient of 0.9 to 2.0.

In a preferred embodiment, the laminated optical film is a film obtained by obliquely extending the optical compensation film.

In a preferred embodiment, the optical compensation layer is a cholesterol alignment cured layer.

In a preferred embodiment, an adhesive layer is provided between the polarizing element and the optical compensation film, and the adhesive layer is composed of a polyvinyl alcohol-based resin, a crosslinking agent, and a metal compound having an average particle diameter of 1 to 100 nm. A colloidal adhesive composition is formed.

In a preferred embodiment, the laminated optical film is formed into a roll shape.

According to another aspect of the present invention, a method of manufacturing a laminated optical film can be provided. This manufacturing method has a long optical compensation film in which the refractive index ellipsoid has a relationship of nx>ny≧nz in the longitudinal direction, and a polarizing element which is elongated and has an absorption axis in the longitudinal direction. a step of forming a laminated body by laminating the polarizing element on one side of the optical compensation film via the adhesive composition so that the longitudinal direction of the optical compensation film coincides with the longitudinal direction of the polarizing element; and the optical compensation film of the laminated body a step of forming an optical compensation layer having a relationship of nx=ny>nz; the method for fabricating the laminated optical film is such that an angle between a slow axis of the optical compensation film and an absorption axis of the polarizing element becomes 5 Lamination is carried out in a manner of ~85°.

A method for producing a laminated optical film according to another aspect of the present invention includes: a one-side laminated refractive index ellipsoid having a long optical compensation film having a relationship of nx>ny≧nz in an index ellipsoid having nx=ny> a step of producing a laminated body in the optical compensation layer of the relationship of nz; and transporting the laminated body and the polarizing element having an elongated shape in the longitudinal direction in the longitudinal direction, and the length direction of the optical compensation film a step of laminating the polarizing element on the side of the optical compensation film of the laminated body via the adhesive composition so as to match the longitudinal direction of the polarizing element; the method of manufacturing the laminated optical film is the slow axis of the optical compensation film The angle formed by the absorption axis of the polarizing element is 5 to 85°.

In a preferred embodiment, the method for producing a laminated optical film further includes the step of collectively cutting or punching the laminated body after laminating the polarizing element, the optical compensation film, and the optical compensation layer.

In a preferred embodiment, the adhesive composition contains a polyvinyl alcohol resin, a crosslinking agent, and a metal compound colloid having an average particle diameter of 1 to 100 nm.

According to another aspect of the present invention, a laminated optical film can be provided. This laminated optical film is produced by the above production method.

According to another aspect of the present invention, a liquid crystal display device can be provided. This liquid crystal display device is a liquid crystal display device in which the laminated optical film is disposed on both sides of a liquid crystal cell, and the laminated optical film is obtained from the same film roll.

According to the present invention, by using a long optical compensation film, it is possible to provide a laminated optical film which is capable of preventing foreign matter from being mixed between a polarizing element and an optical compensation film, and which is excellent in transmittance and polarization. Further, the laminated optical film of the present invention can contribute to the improvement of the contrast of the obtained liquid crystal display device.

Hereinafter, preferred embodiments of the present invention will be described, but the present invention is not limited to the embodiments.

(Definition of terms and symbols)

The terms and symbols in this specification are defined as follows.

(1) Refractive index (nx, ny, nz)

"nx" is the refractive index in the direction in which the refractive index reaches the maximum (ie, the slow axis direction), "ny" is the refractive index in the direction in which the in-plane and the slow axis are orthogonal, and "nz" is the refractive index in the thickness direction. rate.

(2) In-plane phase difference (Re)

The in-plane retardation (Re) is the in-plane retardation value of the layer (film) at a wavelength of 590 nm unless otherwise specified at 23 °C. When the thickness of the layer (film) is d (nm), Re can be obtained from Re = (nx - ny) × d. In the present specification, when it is represented by Re (550), it means the in-plane phase difference of the layer (film) at a wavelength of 550 nm.

(3) Phase difference in the thickness direction (Rth)

The phase difference (Rth) in the thickness direction means a phase difference in the thickness direction of the layer (film) at a wavelength of 590 nm at 23 ° C unless otherwise specified. When the thickness of the layer (film) is d (nm), Rth can be obtained from Rth = (nx - nz) × d. In the present specification, when Rth (550) is used, it means a phase difference in the thickness direction of a layer (film) at a wavelength of 550 nm.

(4) Nz coefficient

The Nz coefficient can be obtained from Nz = Rth / Re.

(5) λ/4 board

The "λ/4 plate" refers to an electro-optical birefringent plate that functions to rotate the polarizing surface of the light beam, and has an optical path difference of 1/4 wavelength between linearly polarized lights that vibrate in the right-angle direction. Features. In other words, it means that the phase between the normal light component and the abnormal light component is shifted by one-fourth of a cycle, and the circularly polarized light is converted into planar polarized light (or planar polarized light is converted into circularly polarized light).

(6) λ/2 board

"λ/2 plate" refers to an electro-optical birefringent plate that functions to rotate the polarizing surface of the light beam, and has a function of generating an optical path difference of 1/2 wavelength between linearly polarized lights vibrating in a right angle direction. . In other words, it means that the phase between the normal light component and the abnormal light component is shifted by one-half cycle.

A. The overall composition of the laminated optical film

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing a laminated optical film according to a preferred embodiment of the present invention. The laminated optical film 10 is provided with a polarizing element 11, an optical compensation film 12, and an optical compensation layer 13 in this order. Further, the laminated optical film 10 includes an adhesive layer 14 between the polarizing element 11 and the optical compensation film 12, and a protective film 15 on the side opposite to the optical compensation film 12 of the polarizing element 11. Although not shown, the laminated optical film 10 is provided with an adhesive layer between the optical compensation film 12 and the optical compensation layer 13 . The laminated optical film 10 is formed into a strip shape. In the present specification, the term "long strip" means that the length (longitudinal direction) is 10 times or more the width (width direction). As described above, by using the long optical compensation film, a laminated optical film excellent in transmittance and polarization can be obtained. Preferably, the laminated optical film of the present invention is formed into a roll shape.

As shown in the example, when the laminated optical film does not have a protective film between the polarizing element and the optical compensation film, the optical compensation film 12 can also function as a protective film. By forming the above configuration, it is possible to contribute to reduction in thickness. Although not shown, the laminated optical film of the present invention may further include other optical compensation elements as needed.

FIG. 2 is an exploded perspective view showing the optical axes of the polarizing element 11 and the optical compensation film 12 constituting the laminated optical film 10 shown in FIG. 1 (the adhesive layer 14 and the protective film 15 are not shown). The polarizing element 11 has an elongated shape and has an absorption axis A in the longitudinal direction. The angle α between the absorption axis A of the polarizing element 11 and the slow axis B of the optical compensation film 12 is 5 to 85°. Within this range, the angle α can be set to any appropriate value in accordance with the optical characteristics of the optical compensation film or the like. For example, when the optical compensation film functions as a λ/4 plate, the angle α is preferably 43.0 to 47.0°, more preferably 44.0 to 46.0°, and particularly preferably 44.5 to 45.5°. When the optical compensation film can function as a λ/2 plate, the angle α is preferably from 13.0 to 17.0°, more preferably from 14.0 to 16.0°, and particularly preferably from 14.5 to 15.5°. When the optical compensation film functions as a λ/2 plate, it is preferable that the laminated optical film is provided on the opposite side of the optical compensation film from the polarizing element, and further includes an optical compensation element capable of functioning as a λ/4 plate. The angle between the slow axis of the optical compensation component and the absorption axis of the polarizing element (clockwise) is preferably 73.0 to 77.0°, more preferably 74.0 to 76.0°, and particularly preferably 74.5 to 75.5°. By adopting the above configuration, it is possible to exhibit a circularly polarized light function in a wide wavelength range. In FIG. 2, the angle α is defined as a clockwise direction with respect to the absorption axis A, but may be defined as a counterclockwise direction. Further, as described below, the in-plane retardation Re of the optical compensation layer 13 is less than 10 nm, and does not have a substantial slow axis in the plane.

A-1. Polarizing element

As the polarizing element 11, any appropriate polarizing element can be employed depending on the purpose. For example, a hydrophilic polymer such as a polyvinyl alcohol-based film, a partially formalized polyvinyl alcohol-based film, or an ethylene-vinyl acetate copolymer-based partial saponified film is adsorbed to a dichroic substance such as iodine or a dichroic dye. The film is further uniaxially stretched; a polyether-based alignment film such as a dehydrated material of polyvinyl alcohol or a dehydrochlorination product of polyvinyl chloride. Among these, it is preferable to adsorb a dichroic substance such as iodine on a polyvinyl alcohol-based film and to perform uniaxial stretching of the polarizing element, which is relatively high in polarized light. The thickness of the polarizing elements is not particularly limited, but is generally about 1 to 80 μm.

A polarizing element obtained by adsorbing iodine on a polyvinyl alcohol-based film and then uniaxially stretching can be produced, for example, by immersing polyvinyl alcohol in an aqueous solution of iodine, dyeing, and extending the iodine. It is 3~7 times the original length. If necessary, it may contain boric acid, zinc sulfate, zinc chloride, or the like, or may be immersed in an aqueous solution of potassium iodide or the like. Further, if necessary, the polyvinyl alcohol-based film may be immersed in water before being dyed, and washed with water.

By washing the polyvinyl alcohol-based film with water, not only the stain on the surface of the polyvinyl alcohol-based film and the anti-caking agent can be washed, but also the effect of preventing unevenness in dyeing unevenness by swelling the polyvinyl alcohol-based film. It can be stretched after dyeing with iodine, or extended while dyeing, or it can be dyed with iodine after stretching. It can also be extended in an aqueous solution or a water bath such as boric acid or potassium iodide.

A-2. Optical compensation film

In one embodiment, the optical compensation film 12 has an index ellipsoid of nx>ny≧nz. Here, "ny=nz" includes not only the case where ny and nz are strictly equal, but also the case where ny and nz are substantially equal. Specifically, the Nz coefficient (Rth/Re) may be 0.9 to 1.1. The in-plane retardation Re of the optical compensation film is preferably 80 to 300 nm. As described above, when the optical compensation film can function as a λ/4 plate, Re is preferably 80 to 190 nm. When the optical compensation film can function as a λ/2 plate, Re is preferably 200 to 300 nm. The Nz coefficient (Rth/Re) is preferably 0.9 to 2.0, more preferably 1.2 to 2.0, and particularly preferably 1.4 to 1.8.

An optical compensation film having an index ellipsoid of nx>ny≧nz can be formed using any suitable material. As a specific example, a polymer film which has been subjected to elongation treatment can be mentioned. As the resin forming the polymer film, any appropriate resin can be employed. Preferably, the optical compensation film contains at least one thermoplastic resin selected from the group consisting of norbornene-based resins, cellulose-based resins, polycarbonate-based resins, and polyester-based resins.

The norbornene-based resin is a resin obtained by polymerizing a norbornene-based monomer as a polymerization unit. Examples of the norbornene-based monomer include norbornene and an alkyl group and/or an alkylene group-substituted one, and examples thereof include 5-methyl-2-norbornene and 5-dimethyl-2. -norbornene, 5-ethyl-2-norbornene, 5-butyl-2-norbornene, 5-ethylidene-2-norbornene, etc., such substituents of polar groups such as halogen Dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc.; dimethicone, its alkyl and/or alkylene substituents, and substituents such as halogens, such as 6 -Methyl-1,4:5,8-dimethyl bridge-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethyl-1,4:5,8-two A bridge-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-ethylene-1,4:5,8-dimethyl bridge-1,4,4a,5,6 ,7,8,8a-octahydronaphthalene, 6-chloro-1,4:5,8-dimethyl bridge-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-cyanide Base-1,4:5,8-dimethyl bridge-1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-pyridyl-1,4:5,8-dimethyl bridge -1,4,4a,5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4:5,8-dimethyl bridge-1,4,4a,5,6, 7,8,8a-octahydronaphthalene, etc.; 3~4 polymer of cyclopentadiene, such as 4,9:5,8-dimethyl bridge-3a,4,4a,5,8,8a,9,9a - octahydro-1H-indole, 4,11:5,10:6,9-tripa bridge-3a,4,4a,5,5a,6,9,9a,10,10a, 11,11a-dodecyl-1H-cyclopentadienylpyrene. The norbornene-based resin may be a copolymer of a norbornene-based monomer and another monomer.

As the polycarbonate resin, an aromatic polycarbonate can be preferably used. The aromatic polycarbonate is typically obtained by the reaction of a carbonate precursor with an aromatic diphenol compound. Specific examples of the carbonate precursor include carbonium chloride, diphenol bischloroformate, diphenyl carbonate, di-p-tolyl carbonate, phenyl p-tolyl carbonate, and di-p-chlorobenzene carbonate. Ester, dinaphthyl carbonate, and the like. Among these, carbonium chloride and diphenyl carbonate are preferred. Specific examples of the aromatic diphenol compound include 2,2-bis(4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3,5-dimethylphenyl)propane, and a double (4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)ethane, 2,2-bis(4-hydroxyphenyl)butane, 2,2-bis(4-hydroxy-3) , 5-dimethylphenyl)butane, 2,2-bis(4-hydroxy-3,5-dipropylphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane or the like. These may be used alone or in combination of two or more. Preferred are 2,2-bis(4-hydroxyphenyl)propane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)-3,3. , 5-trimethylcyclohexane. It is particularly preferred to use 2,2-bis(4-hydroxyphenyl)propane in combination with 1,1-bis(4-hydroxyphenyl)-3,3,5-trimethylcyclohexane. As the cellulose resin, a cellulose ester is preferably used. As the cellulose ester, any appropriate cellulose ester can be employed. As a specific example,

Examples thereof include organic acid esters such as cellulose acetate, cellulose propionate, and cellulose butyrate. Further, the cellulose ester may be, for example, a mixed organic acid ester in which a part of the hydroxyl group of cellulose is substituted with an ethyl fluorenyl group and a propyl fluorenyl group. The cellulose ester can be produced, for example, by the method described in JP-A-2001-188128 [0040] to [0041].

The weight average molecular weight (Mw) of the cellulose ester measured by a gel permeation chromatography (GPC) method using a tetrahydrofuran solvent is preferably 30,000 to 500,000, more preferably 50,000 to 400,000. Especially good is the range of 80,000 to 300,000. When the weight average molecular weight is within the above range, the mechanical strength is excellent, and the workability of solubility, moldability, and casting is good.

Examples of the polyester-based resin include polyethylene terephthalate (PET) and polybutylene terephthalate (PBT).

As a method of forming the above resin into a film shape, any appropriate method can be employed. For example, a hot melt molding method, a solution casting method, and the like can be mentioned. A hot melt forming method is preferred. Specific examples of the heat-melt molding method include a melt extrusion molding method, an extrusion molding method, an inflation method, an injection molding method, a blow molding method, and an extension molding method. Of these, a melt extrusion molding method is preferred. This is because a stretched film excellent in mechanical strength and surface precision can be obtained. The molding conditions can be appropriately selected depending on the purpose of use, the molding method, and the like. In the melt extrusion molding method, the temperature of the cylinder is preferably from 100 to 600 ° C, more preferably from 150 to 350 ° C.

The thickness of the polymer film (unstretched film) can be set to any appropriate value depending on the desired optical characteristics, the following stretching treatment, and the like. It is preferably 10 to 300 μm, more preferably 30 to 200 μm. The reason for this is that a stable elongation treatment can be performed, and a homogeneous stretched film can be obtained.

In the above stretching treatment, any suitable stretching method and stretching conditions (for example, elongation temperature, stretching ratio, and stretching direction) may be employed as long as a long stretch film is obtained. An optical compensation film having the above-described desired optical characteristics (for example, a refractive index ellipsoid, an in-plane phase difference, and a phase difference in the thickness direction) can be obtained by appropriately selecting an extension method and an extension condition. The stretching method preferably includes a method in which the unstretched film is continuously inclined obliquely in a direction at an angle θ to the width direction thereof. By adopting this method, an elongated stretch film having an alignment axis (slow axis) at an angle θ to the width direction of the film can be obtained, whereby the following laminate method can be performed (for example, a roll-to-roll type) ). As a result, it is possible to obtain a laminated optical film which is capable of preventing foreign matter from being mixed between the polarizing element and the optical compensation film and having excellent transmittance and polarization.

The above angle θ can be set to any appropriate value depending on the purpose. A representative example is 5 to 85°. Within this range, the angle θ can be set to any appropriate value depending on the desired optical characteristics and the like. For example, when the optical compensation film can function as a λ/4 plate, the angle θ is preferably 43.0 to 47.0°, more preferably 44.0 to 46.0°, and particularly preferably 44.5 to 45.5°. When the optical compensation film can function as a λ/2 plate, the angle θ is preferably 73.0 to 77.0°, more preferably 74.0 to 76.0°, and particularly preferably 74.5 to 75.5°. The method of obliquely extending is not particularly limited as long as it is continuously stretched in a direction at an angle θ to the width direction of the stretched film, and the alignment axis of the polymer is inclined to a desired angle. method. Examples of the stretching machine for obliquely extending are, for example, a tenter type stretching machine which can apply a conveying force or a stretching force or a pulling force at different speeds in the lateral direction and/or the longitudinal direction. As the tenter type stretching machine, there are a lateral uniaxial stretching machine, a simultaneous biaxial stretching machine, and the like, and any suitable stretching machine can be employed as long as the elongated film can be continuously subjected to the oblique stretching process.

One example of the above-described oblique tenter extension is shown in FIG. As shown in Fig. 3, the unstretched film 12a is conveyed in a fixed direction (for example, the longitudinal direction) 21, and is extended obliquely using the left and right tenters 31 and 31. The film 12a sandwiched between the specific positions 41, 42 can be obliquely extended by moving the left side at a speed 52L toward the position 51L and at the right side at a speed 52R toward the position 51R (in the illustrated example, the speed 52L < the speed 52R). A long stretch film 12 is obtained. The speed ratio (speed difference) of the left and right tenter can be set to any appropriate value according to the above-mentioned required angle θ. The representative example is 1~50%. In addition, FIG. 3 is an example in which the width direction X is inclined at an angle θ in the counterclockwise direction, and the alignment axis (slow axis) may be the B direction.

In addition to the above, Japanese Patent Laid-Open No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. No. Hei. The method described in Japanese Laid-Open Patent Publication No. JP-A-2002-200254, and the like.

When the glass transition temperature of the resin forming the polymer film (unstretched film) is Tg, the temperature at the time of the oblique stretching is preferably Tg-30 ° C to Tg + 60 ° C, more preferably Tg - 10 ° C ~ Tg + 50 ° C. Further, the representative example of the stretching ratio is 1.01 to 30 times, preferably 1.01 to 10 times, more preferably 1.01 to 5 times.

The thickness of the film obtained by the above oblique stretching is typically 20 to 80 μm, preferably 30 to 60 μm, more preferably 30 to 45 μm.

A-3. Optical compensation layer

The optical compensation layer 13 described above has an index ellipsoid of nx=ny>nz. Here, "nx=ny" includes not only the case where nx and ny are strictly equal, but also the case where nx and ny are substantially equal. Specifically, it means that Re is less than 10 nm. By providing an optical compensation layer having such optical characteristics, the contrast of the obtained liquid crystal display device can be improved. The phase difference Rth in the thickness direction of the optical compensation layer 13 can be set to any appropriate value. It is preferably 25 to 300 nm, more preferably 50 to 270 nm, and particularly preferably 75 to 250 nm.

The optical compensation layer may be formed of any suitable material as long as the above characteristics are obtained. Specific examples of the optical compensation layer include a cholesterol alignment cured layer. The "cholesterol alignment solidified layer" refers to a layer in which the constituent molecules of the layer have a helical structure, the helical axis thereof is aligned substantially perpendicular to the plane direction, and the alignment state thereof is fixed. Therefore, the "cholesterol alignment solidified layer" includes not only the case where the liquid crystal compound exhibits a cholesteric liquid crystal phase but also the case where the non-liquid crystal compound has a virtual structure of a cholesteric liquid crystal phase. For example, the "cholesterol alignment solidified layer" can be formed by twisting a liquid crystal material to exhibit a liquid crystal phase, and aligning it with a light-emitting agent to form a cholesterol structure (helical structure). A polymerization treatment or a crosslinking treatment, whereby the alignment of the liquid crystal material (cholesterol structure) is fixed.

Specific examples of the above-mentioned cholesterol alignment-cured layer include a cholesterol layer described in JP-A-2003-287623.

The thickness of the optical compensation layer can be set to any appropriate value as long as the desired optical characteristics are obtained. When the optical compensation layer is a cholesterol alignment solidified layer, the thickness is preferably 0.5 to 10 μm, more preferably 0.5 to 8 μm, and particularly preferably 0.5 to 5 μm.

Another specific example of the material for forming the optical compensation layer 13 is a non-liquid crystal material. Particularly preferred is a non-liquid crystalline polymer. Such a non-liquid crystal material differs from a liquid crystal material in that, irrespective of the alignment property of the substrate, a film exhibiting optical uniaxiality of nx=ny>nz can be formed according to its own properties. As the non-liquid crystal material, for example, in terms of heat resistance, chemical resistance, transparency, and rigidity, polyamine, polyimide, polyester, polyether ketone, and polyamidoxime are preferred. A polymer such as an imine or a polyester quinone. Any of these polymers may be used singly, and for example, a mixture of two or more kinds having different functional groups may be used as in the case of a mixture of polyaryletherketone and polyamine. Among such polymers, polyylidene is particularly preferred in terms of high transparency, high alignment, and high elongation.

Specific examples of the polyimine and the method for forming the optical compensation layer include a polymer and a method for producing an optical compensation film described in JP-A-2004-46065.

The thickness of the optical compensation layer can be set to any appropriate value as long as the desired optical characteristics are obtained. When the optical compensation layer 13 is formed of a non-liquid crystal material, it is preferably 0.5 to 10 μm, more preferably 0.5 to 8 μm, and particularly preferably 0.5 to 5 μm.

A-4. Adhesive layer

As the adhesive for forming the above-mentioned adhesive layer 14, any appropriate adhesive composition can be employed. Preferably, the adhesive layer 14 is formed of an adhesive composition containing a polyvinyl alcohol-based resin, a crosslinking agent, and a metal compound colloid having an average particle diameter of 1 to 100 nm.

Examples of the polyvinyl alcohol-based resin include a polyvinyl alcohol resin and a polyvinyl alcohol resin containing an ethylene glycol group. Preferred is a polyvinyl alcohol resin containing an ethyl acetonitrile group. The reason for this is that durability can be improved.

Examples of the polyvinyl alcohol-based resin include a saponified product of polyvinyl acetate, a derivative of the saponified product, a saponified product of a copolymer of vinyl acetate and a copolymerizable monomer, and a polyvinyl alcohol condensate. A modified polyvinyl alcohol obtained by hydroformylation, urethaneization, etherification, grafting, or phosphation. Examples of the monomer include unsaturated carboxylic acids such as maleic acid (anhydride), fumaric acid, crotonic acid, itaconic acid, and (meth)acrylic acid, and esters thereof; ethylene and propylene. And other α-olefins; (meth)allylsulfonic acid (sodium), (succinic acid monoalkyl ester) sodium sulfonate, (alkyl maleate) sodium disulfonate, N- Hydroxymethyl acrylamide, acrylamide sulfonate alkali metal salt, N-vinyl pyrrolidone, N-vinyl pyrrolidone derivative, and the like. These resins may be used singly or in combination of two or more.

In terms of adhesion, the average degree of polymerization of the above polyvinyl alcohol-based resin is preferably from about 100 to 5,000, more preferably from 1,000 to 4,000. In terms of adhesion, the average degree of saponification is preferably from about 85 to 100 mol%, more preferably from 90 to 100 mol%.

The polyvinyl alcohol-based resin containing the ethyl acetate group can be obtained, for example, by reacting a polyvinyl alcohol-based resin with diketene by any method. Specific examples thereof include a method of adding diketene to a dispersion obtained by dispersing a polyvinyl alcohol-based resin in a solvent such as acetic acid, and dissolving the polyvinyl alcohol-based resin in dimethylformamide or A method of adding diketene to a solution obtained by using a solvent such as dioxane; or a method of directly contacting diketene gas or liquid diketene with a polyvinyl alcohol-based resin.

The representative example of the degree of modification of the ethylenic acid group of the polyvinyl alcohol-based resin containing the ethyl acetonitrile group is 0.1 mol% or more, preferably about 0.1 to 40 mol%, more preferably 1~. 20%, especially good is 2~7 mol%. If it is less than 0.1 mol%, the water resistance is insufficient. If it exceeds 40% by mole, the water resistance improvement effect is small. Further, the degree of modification of the acetamidine group is a value measured by NMR (nuclear magnetic resonance).

As the above crosslinking agent, any appropriate crosslinking agent can be employed. It is preferably a compound having at least two functional groups reactive with the above polyvinyl alcohol-based resin. For example, an alkylenediamine having an alkylene group and two amine groups such as ethylenediamine, triethylenediamine, and hexamethylenediamine; toluene diisocyanate, hydrogenated toluene diisocyanate, and trimethylolpropane; Isocyanate, toluene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis(4-phenylmethane triisocyanate), isophorone diisocyanate, and the like, ketone oxime block or phenol block Ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether or glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethylolpropane tricondensate Ethylenes such as glyceryl ether, diglycidyl aniline, diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde; glyoxal, malondialdehyde, succinaldehyde, glutaraldehyde, Dialdehydes such as maleic acid and phthalaldehyde; methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetamide, benzopyrene Amine-formaldehyde resin such as condensate of amine and formaldehyde; sodium, potassium, magnesium, calcium, aluminum, iron, nickel, etc. Metal, or a salt of a trivalent metal and oxides thereof. Preferred among these are amine-formaldehyde resins or dialdehydes. As the amino-formaldehyde resin, a compound having a methylol group is preferred, and as the dialdehyde, glyoxal is preferred. Among them, preferred are compounds having a methylol group, and particularly preferred is methylol melamine.

The amount of the crosslinking agent to be added can be appropriately set depending on the type of the polyvinyl alcohol-based resin or the like. The representative example is about 10 to 60 parts by weight, preferably 20 to 50 parts by weight, per 100 parts by weight of the polyvinyl alcohol-based resin. The reason for this is that the adhesion can be optimized. Further, when the amount of the crosslinking agent is large, there is a tendency that the crosslinking agent is reacted in a short time to gel the adhesive. As a result, the usable time (pot life) of the adhesive is extremely shortened, and it is difficult to be industrially used. Since the adhesive of the present embodiment contains the following metal compound colloid, even when the amount of the crosslinking agent is large, it can be used with good stability.

The metal compound colloid may be obtained by dispersing fine particles of the metal compound in a dispersion medium, and may be electrostatically stabilized due to mutual repulsion of the same kind of charges of the fine particles, thereby having sustained stability. The average particle diameter of the fine particles forming the metal compound colloid may be any appropriate value as long as it does not adversely affect optical characteristics such as polarization characteristics. It is preferably 1 to 100 nm, more preferably 1 to 50 nm. This is because the fine particles can be uniformly dispersed in the adhesive layer to ensure the adhesion and the occurrence of crack defects can be suppressed. Furthermore, the term "crack point defect" means light leakage. The details are described below.

As the above metal compound, any appropriate compound can be employed. For example, metal oxides such as alumina, ceria, zirconia, and titania; metal salts such as aluminum citrate, calcium carbonate, magnesium citrate, zinc carbonate, cesium carbonate, and calcium phosphate; diatomaceous earth, talc, and Minerals such as clay and kaolin. As described below, it is preferred in the present invention to use a metal compound colloid having a positive charge. Examples of the metal compound include alumina, titanium oxide, and the like, and alumina is particularly preferable.

A typical example of the above metal compound colloid is that it is dispersed in a dispersion medium and exists as a colloidal solution. Examples of the dispersion medium include water and alcohol. A representative example of the solid content concentration in the colloidal solution is about 1 to 50% by weight, preferably 1 to 30% by weight. The colloidal solution may contain an acid such as nitric acid, hydrochloric acid or acetic acid as a stabilizer.

The amount of the metal compound colloid (solid content) is preferably 200 parts by weight or less, more preferably 10 to 200 parts by weight, even more preferably 20 to 175 parts by weight based on 100 parts by weight of the polyvinyl alcohol-based resin. The best part is 30 to 150 parts by weight. The reason for this is that the adhesion can be ensured, and the occurrence of crack defects can be suppressed.

The adhesive composition of the present embodiment may contain a coupling agent such as a decane coupling agent or a titanium coupling agent, and various stabilizers such as a tackifier, an ultraviolet absorber, an antioxidant, a heat-resistant stabilizer, and a hydrolysis-resistant stabilizer.

The form of the adhesive composition of the present embodiment is preferably an aqueous solution (resin solution). The resin concentration is preferably from 0.1 to 15% by weight, more preferably from 0.5 to 10% by weight, in terms of coatability and standing stability. The viscosity of the resin solution is preferably from 1 to 50 mPa ‧ s. According to the adhesive composition of the present embodiment, the occurrence of crack defects can be suppressed in a low viscosity range of 1 to 20 mPa·s. The pH of the resin solution is preferably from 2 to 6, more preferably from 2.5 to 5, more preferably from 3 to 5, most preferably from 3.5 to 4.5. Generally, the surface charge of the metal compound colloid can be controlled by adjusting the pH. The surface charge is preferably a positive charge. By having a positive charge, the occurrence of crack defects can be further suppressed. Further, the surface charge can be confirmed, for example, by measuring the kinematic potential using a potentiodynamic measuring machine.

The preparation method of the above resin solution may be any appropriate method. For example, a method in which a polyvinyl alcohol-based resin and a crosslinking agent are mixed in advance and adjusted to an appropriate concentration, and a metal compound colloid is blended therein may be mentioned. Further, the polyvinyl alcohol-based resin may be mixed with the metal compound colloid, and the crosslinking agent may be mixed while considering the use time or the like. Further, the concentration of the resin solution can also be adjusted after preparing the resin solution.

The thickness of the adhesive layer formed of the above adhesive composition is preferably from 10 to 300 nm, more preferably from 10 to 200 nm, particularly preferably from 20 to 150 nm.

A-5. Protective film

The above protective film 15 can be formed of any suitable film which can be used as a protective layer of a polarizing element. Specific examples of the material of the main component of the film include a cellulose resin such as triethyl cellulose (TAC), or a polyester resin, a polyvinyl alcohol resin, a polycarbonate resin or a polyamine. A transparent resin such as a polyimide, a polyether oxime, a polyfluorene, a polystyrene, a polynorbornene, a polyolefin, a (meth)acrylic or an acetate. Further, examples thereof include a thermosetting resin such as a (meth)acrylic resin, a urethane resin, a (meth)acrylic urethane resin, an epoxy resin or a polyoxyxylene resin, or an ultraviolet curable resin. Other than this, a glassy polymer such as a siloxane oxide polymer is mentioned. Further, a polymer film described in JP-A-2001-343529 (WO 01/37007) can also be used. As the material of the film, for example, a thermoplastic resin having a substituted or unsubstituted quinone imine group on the side chain, and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in a side chain may be used. The resin composition may, for example, be a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer. The polymer film can be, for example, an extrusion molded product of the above resin composition.

The (meth)acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C or more, more preferably 120 ° C or more, more preferably 125 ° C or more, and particularly preferably 130 ° C or more. The reason for this is that excellent durability can be obtained. The upper limit of the Tg of the (meth)acrylic resin is not particularly limited, and is preferably 170 ° C or less from the viewpoint of moldability and the like.

As the (meth)acrylic resin, any suitable (meth)acrylic resin can be used without departing from the effects of the present invention. For example, poly(meth)acrylate such as polymethyl methacrylate, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth) acrylate copolymer, methyl group Methyl acrylate-acrylate-(meth)acrylic acid copolymer, methyl (meth)acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-A) A cyclohexyl acrylate copolymer, a methyl methacrylate-(meth)acrylic acid norbornyl ester copolymer, etc.). A poly(meth)acrylic acid C _1-6 alkyl ester such as poly(methyl) acrylate is preferable. More preferably, a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight) is used.

Specific examples of the (meth)acrylic resin include, for example, ACRYPET VH or ACRYPET VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and a molecule having a ring as described in JP-A-2004-70296 A (meth)acrylic resin having a high Tg obtained by intramolecular crosslinking or intramolecular cyclization of a structural (meth)acrylic resin.

The (meth)acrylic resin is particularly preferably a (meth)acrylic resin having a lactone ring structure in terms of high heat resistance, high transparency, and high mechanical strength.

Examples of the (meth)acrylic resin having a lactone ring structure include JP-A-2000-230016, JP-A-2001-151814, JP-A-2002-120326, and Japan. A (meth)acrylic resin having a lactone ring structure described in JP-A-2005-146084, and the like.

The mass average molecular weight (sometimes referred to as a weight average molecular weight) of the (meth)acrylic resin having a lactone ring structure is preferably from 1,000 to 2,000,000, more preferably from 5,000 to 1,000,000, more preferably 10,000. 500000, especially good is 50000~500000.

The Tg (glass transition temperature) of the (meth)acrylic resin having a lactone ring structure is preferably 115 ° C or higher, more preferably 125 ° C or higher, more preferably 130 ° C or higher, and particularly preferably 135. °C, the best is above 140 °C. The reason for this is that excellent durability can be obtained. The upper limit of the Tg of the (meth)acrylic resin having a lactone ring structure is not particularly limited, and is preferably 170 ° C or less from the viewpoint of moldability and the like.

In the present specification, the term "(meth)acrylic" means acrylic or methacrylic.

The protective film 15 is preferably transparent and has no coloration. The phase difference Rth in the thickness direction of the protective film is preferably -90 nm to +90 nm, more preferably -80 nm to +80 nm, more preferably -70 nm to +70 nm.

The thickness of the protective film may be any appropriate thickness as long as the phase difference Rth in the above-described preferable thickness direction can be obtained. A representative example of the thickness of the protective film is 5 mm or less, preferably 1 mm or less, more preferably 1 to 500 μm, still more preferably 5 to 150 μm.

The side opposite to the polarizing element of the protective film may be subjected to a hard coating treatment, an antireflection treatment, a release treatment, an antiglare treatment, or the like as needed.

As described above, when the cellulose-based film which is generally used as a protective layer of a polarizing element is, for example, a triethylenesulfonated cellulose film, the phase difference Rth in the thickness direction is about 60 nm at a thickness of 80 μm. Therefore, in order to obtain a phase difference Rth in a smaller thickness direction, a suitable treatment for lowering Rth can be performed on the cellulose film having a larger Rth.

As a process for reducing the phase difference Rth in the thickness direction described above, any appropriate processing method can be employed. For example, a base material such as polyethylene terephthalate coated with a solvent such as cyclopentanone or methyl ethyl ketone, polypropylene or stainless steel may be bonded to a common cellulose film and heated. Drying (for example, drying at about 80 to 150 ° C for about 3 to 10 minutes), then peeling off the base film; dissolving norbornene resin, acrylic resin, etc. in cyclopentanone, methyl ethyl In a solvent such as a ketone, the obtained solution is applied onto a common cellulose film, and dried by heating (for example, dried at about 80 to 150 ° C for about 3 to 10 minutes), and then the coating film is peeled off. Wait.

The material constituting the cellulose film is preferably a fatty acid-substituted cellulose polymer such as diethyl ketone cellulose or triethylene sulfonyl cellulose. Generally, the acetic acid substitution degree of triacetonitrile cellulose used is about 2.8, preferably the degree of substitution of acetic acid is controlled to 1.8 to 2.7, and more preferably, the degree of substitution of propionic acid is controlled to 0.1 to 1, thereby The phase difference Rth in the thickness direction is controlled to be small.

By adding a plasticizer such as dibutyl phthalate, p-toluenesulfonyl aniline or triethyl citrate to the cellulose-based polymer, the phase difference Rth in the thickness direction can be controlled to be small. . The amount of the plasticizer added is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, still more preferably 1 to 15 parts by weight, per 100 parts by weight of the fatty acid-substituted cellulose-based polymer.

The treatment for reducing the phase difference Rth in the thickness direction may be used in combination as appropriate. The phase difference Rth (550) in the thickness direction of the protective film obtained by performing such treatment is preferably -20 nm to +20 nm, more preferably -10 nm to +10 nm, more preferably -6 nm to +6 nm, especially The good is -3nm~+3nm. The in-plane retardation Re (550) of the protective film is preferably 0 nm or more and 10 nm or less, more preferably 0 nm or more and 6 nm or less, more preferably 0 nm or more and 3 nm or less.

The thickness of the protective film may be any appropriate thickness as long as the phase difference Rth in the thickness direction described above is obtained. The thickness of the above protective film is preferably from 20 to 200 μm, more preferably from 30 to 100 μm, still more preferably from 35 to 95 μm.

A-6. Others

As an adhesive for forming an adhesive layer provided between the optical compensation film 12 and the optical compensation layer 13, any appropriate adhesive can be employed. It is preferred to use a hardening type adhesive. A typical example of the curing adhesive is a photocurable adhesive such as an ultraviolet curing type, a moisture curing adhesive, and a thermosetting adhesive. Specific examples of the thermosetting adhesive include thermosetting resin-based adhesives such as an epoxy resin, an isocyanate resin, and a polyimide resin. Specific examples of the moisture-curing adhesive include an isocyanate resin-based moisture-curing adhesive. Among these, a moisture-curing type adhesive (particularly an isocyanate resin-based moisture-curing type adhesive) is preferred. Since the moisture-curing adhesive is cured by reacting with moisture in the air or adsorbed water on the surface of the adherend, an active hydrogen group such as a hydroxyl group or a carboxyl group, and the like, it can be naturally left by applying an adhesive and then placing it. Hardened and excellent in workability. Further, since it is not necessary to perform heating for curing, the optical compensation layer is not heated at the time of lamination. As a result, there is no need to worry about heat shrinkage. Therefore, according to the present invention, even when the optical compensation layer is extremely thin, cracking or the like at the time of lamination can be remarkably prevented. Further, even if the hardening type adhesive is heated after being cured, it hardly expands and contracts. In addition, the above-mentioned isocyanate resin-based adhesive is a general term for a polyisocyanate-based adhesive and a urethane-resin adhesive.

The above various curable resins can be dissolved or dispersed in a solvent and used as a hardening type resin binder solution (or dispersion). In the preparation of the solution (or dispersion), the solid content of the hardening type resin is preferably from 10 to 80% by weight, more preferably from 20 to 65% by weight, particularly preferably from 25 to 65 parts by weight. %, the best is 30~50% by weight. Any suitable solvent can be used as the solvent. For example, ethyl acetate, methyl ethyl ketone, methyl isobutyl ketone, toluene, xylene, etc. are mentioned. These may be used alone or in combination of two or more.

The thickness of the above-mentioned adhesive layer is preferably from 0.1 μm to 20 μm, more preferably from 0.5 μm to 15 μm, still more preferably from 1 μm to 10 μm.

As described above, the laminated optical film of the present invention may further comprise other optical compensation elements. The optical compensation component can have any suitable optical characteristics. Examples of the form thereof include a stretch film of a polymer film, a liquid crystal coat layer, and the like. Examples of the resin forming the polymer film include a polycarbonate resin and a norbornene resin. As the stretching method, uniaxial stretching and biaxial stretching are exemplified. By providing other optical compensation elements, for example, the above optical compensation film can be obtained, and a circular polarization function can be exhibited over a wide wavelength range.

B. Manufacturing method

The method for producing a laminated optical film according to the present invention has a step of conveying a long optical compensation film having a relationship of nx>ny≧nz in the longitudinal direction of the refractive index ellipsoid, and having a long shape and having a length in the longitudinal direction. The polarizing element of the absorption axis laminates the polarizing element on one side of the optical compensation film via the adhesive composition so that the longitudinal direction of the optical compensation film coincides with the longitudinal direction of the polarizing element. By laminating the polarizing element and the optical compensation film, it is possible to provide a laminated optical film which can prevent foreign matter from being mixed between the polarizing element and the optical compensation film and which is excellent in transmittance and polarization. The strip-shaped polarizing element is preferably formed into a roll shape. The long optical compensation film is preferably formed into a roll shape.

The polarizing element and the optical compensation film are laminated via an adhesive composition. Specifically, a method of applying an adhesive composition to one surface of one of a polarizing element or an optical compensation film, and then attaching the polarizing element to the optical compensation film and drying the film may be mentioned. As the adhesive composition, any appropriate adhesive composition can be employed. It is preferred to use the adhesive composition described in the above item A-4. Examples of the coating method of the adhesive composition include a roll coating method, a spray method, a dipping method, and the like. Further, it is preferred to apply the coating so that the thickness after drying is larger than the average particle diameter of the colloid of the metal compound. Representative examples are 10 to 300 nm, preferably 10 to 200 nm, more preferably 20 to 150 nm. By coating to the above thickness, a sufficient adhesion can be obtained. A representative example of the drying temperature is 5 to 150 ° C, preferably 30 to 120 ° C. A representative example of the drying time is 120 seconds or longer, preferably 300 seconds or longer.

The polarizing element and the optical compensation film are laminated such that the angle between the slow axis of the optical compensation film and the absorption axis of the polarizing element is 5 to 85°. As described above, when the optical compensation film can function as a λ/4 plate, it is preferably 43.0 to 47.0°, more preferably 44.0 to 46.0°, and particularly preferably 44.5 to 45.5°. When the optical compensation film can function as a λ/2 plate, it is preferably 13.0 to 17.0 °, more preferably 14.0 to 16.0 °, and particularly preferably 14.5 to 15.5 °.

The method for producing a laminated optical film of the present invention further comprises the step of: optically compensating the laminated index ellipsoid on the other side of the optical compensation film (on the side where the polarizing element is not disposed) having a relationship of nx=ny>nz Floor. In a typical example, an optical compensation layer is laminated on an optical compensation film in a state in which an optical compensation layer is formed on a substrate in advance to form a laminate. In this case, the optical compensation layer formed on the substrate is transferred from the substrate to the optical compensation film. The optical compensation film and the optical compensation layer are typically laminated via an adhesive. As the adhesive, any appropriate adhesive can be employed. It is preferred to use the adhesive described in the above item A-6. The coating amount of the subsequent agent (adhesive solution or dispersion) can be appropriately set depending on the purpose. The coating amount is preferably from 0.3 to 3 ml, more preferably from 0.5 to 2 ml, particularly preferably from 1 to 2 ml, per unit area (cm ² ) of the optical compensation layer. The thickness of the above-mentioned adhesive layer can be satisfied by adjusting the coating amount within the above range. Further, the solvent contained in the adhesive may be volatilized by natural drying or heat drying after application as needed.

The method for producing a laminated optical film of the present invention may further comprise a step of laminating an elongated protective film on a side of the polarizing element opposite to the optical compensation film. Specifically, a method of laminating the polarizing element in the longitudinal direction and the longitudinal direction of the protective film while transporting the polarizing element and the protective film in the longitudinal direction is exemplified. The long protective film is preferably formed into a roll shape. The polarizing element and the protective film may be laminated via any suitable adhesive layer. In forming the adhesive layer, it is preferred to use the adhesive composition described in the above item A-4.

One of the steps of the method for producing the laminated optical film of the present invention is shown in Fig. 4 . As shown in FIG. 4, the laminated body 110 in which the protective film 15 is laminated on the polarizing element 11 and the optical compensation film 12 coated with the above-mentioned adhesive composition (not shown) are sent in the direction of the arrow so that each The state in which the length directions are the same is attached. That is, the polarizing element 11 and the optical compensation film 12 are continuously laminated by a Roll-to-Roll to obtain the laminated body 120. Further, in Fig. 4, reference numerals 111 and 112 denote rolls for winding a film forming each layer, and reference numeral 113 denotes a guide roll for bonding the films to each other.

The other steps in an example of the method for producing the laminated optical film of the present invention are shown in Fig. 5 (a) and Fig. 5 (b). As shown in FIG. 5(a), the laminated body 120 (the protective film 15, the laminated body of the polarizing element 11 and the optical compensation film 12) and the laminated body 121 formed by coating the optical compensation layer 13 on the substrate 13a are provided. The electrodes are fed in the direction of the arrow, and are bonded together by the above-mentioned adhesive (not shown) in a state in which their respective longitudinal directions are aligned. By laminating the optical compensation layer and the optical compensation film, it is possible to provide a laminated optical film which is capable of preventing foreign matter from being mixed between the optical compensation layer and the optical compensation film and having excellent transmittance and polarization. Finally, the substrate 13a is peeled off from the laminated body 130 to be bonded in the manner shown in Fig. 5(b). Further, in Fig. 5(a), reference numerals 114 and 115 denote rolls for winding a film forming each layer, and reference numeral 116 denotes a guide roll for bonding the films to each other.

In the above embodiment, the optical compensation layer 13 is laminated after the layered polarizing element 11 and the optical compensation film 12 are laminated. However, the optical compensation layer 12 and the optical compensation layer 13 may be laminated, and then the polarizing element 11 may be laminated.

The method for producing a laminated optical film of the present invention preferably further comprises the steps of: laminating a polarizing element, an optical compensation film, and an optical compensation layer, and then collectively cutting or punching the laminated body. When the protective film is laminated, it is preferred that the protective film is also cut or punched together with the laminated body. Cutting or punching can be done in any suitable way. The laminated optical film obtained by cutting or punching may of course not be elongated.

When the laminated optical film of the present invention further includes another optical compensation element, it can be laminated via any appropriate adhesive layer or adhesive layer.

C. Liquid crystal display device

The liquid crystal display device of the present invention comprises the above laminated optical film. In a liquid crystal display device of a preferred embodiment of the present invention, the laminated optical film is disposed on both sides of the liquid crystal cell. In the liquid crystal display device of the present invention, the laminated optical film is disposed such that the optical compensation layer is in contact with the liquid crystal cell. The laminated optical film disposed on both sides of the liquid crystal cell is preferably obtained by the same film roll. The axial shift can be suppressed by disposing the laminated optical film obtained by the same film roll on both sides of the liquid crystal cell.

The liquid crystal display device may be a transmissive type that views light from a rear surface of the liquid crystal panel to view a screen, or may be a reflective type that views light from a visual side of the liquid crystal panel. Alternatively, the liquid crystal display device may be a semi-transmissive type having both a transmissive type and a reflective type.

The liquid crystal display device of the present invention can be used for any suitable purpose. The use of the liquid crystal display device is not particularly limited. Specifically, it can be applied to OA (office automation) machines such as personal computer screens, notebook computers, photocopying machines, etc.; mobile phones, clocks, digital cameras, portable information terminals (PD A (personal digital assistant, personal digital assistant) )), mobile games and other mobile devices; cameras, LCD TVs, microwave ovens and other household appliances; rear monitors, car navigation system monitors, car audio and other vehicle-mounted devices; commercial stores with information monitors, etc.; Use a guard machine such as a monitor; care monitors, medical monitors, etc., medical equipment, etc.

Hereinafter, the present invention will be specifically described by way of examples, but the present invention is not limited to the examples. Further, the method of measuring the phase difference value between the optical compensation film and the optical compensation layer is as follows.

(Measurement of phase difference)

Automatic measurement was performed using KOBRA-WPR manufactured by Prince. The measurement wavelength was 590 nm, and the measurement temperature was 23 °C.

[Example 1] (production of polarizing element)

After dyeing a long strip of polyvinyl alcohol film in an aqueous solution containing iodine, it is uniaxially stretched by 6 times between rolls having different speed ratios in an aqueous solution containing boric acid, and has an absorption axis in the longitudinal direction. Long strip polarizing element. After extending the long strip-shaped polarizing element, it is wound up to obtain a wound body.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the obtained unstretched film (thickness: 100 μm) was placed in a tenter type stretching machine and heated to 150 °C. The film is conveyed in the longitudinal direction, and the left and right tenter speed ratio (speed difference) is adjusted to 50% to extend in the lateral direction of the film, and is extended in the film transport direction, thereby obtaining a strip optical having a thickness of 40 μm. Compensation film (stretch film).

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm, and the Nz coefficient was 1.05.

(production of optical compensation layer)

90 parts by weight of the nematic liquid crystal compound represented by the following chemical formula (1), 10 parts by weight of the optical agent represented by the following chemical formula (2), and a photopolymerization initiator (Irgacure 907: manufactured by Ciba Specialty Chemicals Co., Ltd.) 5 parts by weight and 300 parts by weight of methyl ethyl ketone were uniformly mixed to prepare a liquid crystal coating liquid. Next, the liquid crystal coating liquid was applied onto a long strip substrate (biaxially stretched PET film), heat-treated at 80 ° C for 3 minutes, and then irradiated with ultraviolet rays to carry out polymerization treatment, thereby forming a cholesterol which becomes an optical compensation layer on the substrate. Oriented to the cured layer. The thickness of the cholesterol alignment solidified layer was 3 μm, the phase difference Rth in the thickness direction was 120 nm, and the in-plane phase difference Re was substantially zero.

(protective film)

As a protective film, a long strip of triacetonitrile cellulose film (thickness 40 μm, manufactured by Konica Minolta Co., Ltd., trade name: KC4UYW) was used. The protective film is made into a wound body and is ready for use. Further, the in-plane retardation Re of the protective film was 5 nm, and the phase difference Rth in the thickness direction was 45 nm.

(Preparation of adhesive composition)

100 parts by weight of the polyvinyl alcohol-based resin (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, ethylation degree: 5 mol%) containing acetamidine group at 30 ° C 50 parts by weight of methylol melamine was dissolved in pure water under temperature to obtain an aqueous solution having a solid concentration of 3.7%. An adhesive composition was prepared by adding 18 parts by weight of an aqueous solution of an alumina colloid (having an average particle diameter of 15 nm and a solid content of 10%, a positive charge) to 100 parts by weight of the aqueous solution. The viscosity of the subsequent composition was 9.6 mPa ‧ s. The pH of the subsequent composition is from 4 to 4.5.

(Production of laminated optical film)

After preparing the above-mentioned adhesive composition, the optical compensation film and the protective film were respectively sent out from the wound body after 30 minutes, and the adhesive composition was applied to each of the single surfaces so that the thickness after drying became 80 nm. An adhesive layer is formed. Thereafter, the optical compensation film on which the adhesive layer is formed is moved on one surface of the polarizing element sent from the wound body, and the protective film on which the adhesive layer is formed is moved on the other surface, and a roll machine is used. These were bonded together and wound up in a gas atmosphere of 55 ° C for 6 minutes, and then wound up to form a long laminated body A. Further, the optical compensation film is bonded such that the slow axis thereof and the absorption axis of the polarizing element are formed at 45 degrees in the clockwise direction.

While the layered product A obtained above was sent out from the wound body, an isocyanate-based cured layer which is an optical compensation layer was attached to the side of the optical compensation film of the layered product A by an isocyanate-based adhesive (thickness: 2 μm). Thereafter, the substrate (biaxially stretched PET film) was removed, and a long laminated optical film obtained by transferring a cholesterol alignment cured layer onto the layered product A was produced. The thickness of the laminated optical film obtained in this manner was 115 μm.

[Embodiment 2]

A laminated optical film was obtained in the same manner as in Example 1 except that the optical compensation film was used, and the optical compensation film was bonded so that the slow axis of the optical compensation film and the absorption axis of the polarizing element were 165° in the clockwise direction. . The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 60 μm) obtained thereby was sandwiched in a tenter type stretcher and heated to 120 ° C. . While transporting the film in the longitudinal direction, the left and right tenter speed ratio (speed difference) is adjusted to 10% to extend in the lateral direction of the film, and also in the film transport direction to obtain a strip-shaped optical having a thickness of 35 μm. Compensation film (stretch film).

In the above manner, an elongated optical compensation film having a slow axis in the direction of 165° clockwise in the longitudinal direction was obtained. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 270 nm, and the Nz coefficient was 1.

[Example 3]

A laminated optical film was prepared in the same manner as in Example 1 except that the aqueous alumina colloid solution was not added in the preparation of the adhesive composition. The thickness of the laminated optical film thus obtained was 115 μm.

[Example 4] (Production of polarizing plate roll body)

After preparing the above-mentioned adhesive composition (see Example 1), the protective film (see Example 1) was sent out from the wound body after 30 minutes, and the single-sided coating was applied so as to have a thickness of 80 nm after drying. The composition is then applied to form an adhesive layer. Thereafter, the protective film on which the adhesive layer was formed was moved on both surfaces of the polarizing element which was fed from the wound body, and was bonded by a roll machine, and passed through a gas atmosphere at 55 ° C for 6 minutes. A long laminated film (so-called polarizing plate roll body) was produced.

(Production of laminated optical film)

Then, the polarizing plate roll body and the optical compensation film (see Example 1) were fed from the wound body, and the laminated body was bonded to each other via an acrylic adhesive (thickness: 12 μm) to form a long laminated body B. . Further, the optical compensation film is bonded such that the slow axis of the optical compensation film and the absorption axis of the polarizing element are 45° in the clockwise direction.

While the layered body B obtained above was sent out from the wound body, an isocyanate-based adhesive (having a thickness of 2 μm) was applied to the optical compensation film side of the layered body B to the long-chained cholesterol alignment-cured layer of the optical compensation layer. Thereafter, the above substrate (biaxially stretched PET film) was removed to prepare a long laminated optical film in which the cholesterol alignment cured layer was transferred onto the layered body B. The thickness of the laminated optical film thus obtained was 115 μm.

(Comparative Example 1) (Production of polarizing plate roll body)

An adhesive composition was prepared in the same manner as in Example 1 except that the aqueous alumina colloid solution was not added. A polarizing plate roll was prepared in the same manner as in Example 4 except that the adhesive composition was used.

(production of optical compensation film)

The strip-shaped norbornene-based resin film (manufactured by Zeon Corporation of Japan, trade name Zeonor, thickness 40 μm, light transmittance coefficient 3.10×10 ^-12 m ² /N) was uniaxially stretched to 1.52 times at 140° C., thereby Make long strips of film. The film had a thickness of 35 μm, an in-plane retardation Re of 140 nm, and an Nz coefficient (Rth/Re) of 1.05.

(Production of laminated optical film)

A laminated sheet of a specific size was cut out from the obtained polarizing plate roll body and the optical compensation film, and laminated by an acrylic adhesive (thickness: 12 μm) to obtain a laminated body C. At this time, lamination is performed such that the slow axis of the optical compensation film and the absorption axis of the polarizing element are 45 degrees in the counterclockwise direction.

Then, an isocyanate-based adhesive (having a thickness of 2 μm) was applied to the optical compensation film side of the layered product C to form a long-length cholesterol alignment cured layer which became an optical compensation layer. Thereafter, the substrate (biaxially stretched PET film) is removed, and a layered body obtained by transferring the cholesterol alignment solidified layer onto the layered body C is obtained.

The obtained laminate was cut into a size of 100 mm × 100 mm to obtain a laminated optical film. The thickness of the laminated optical film thus obtained was 153 μm.

(Comparative Example 2)

A laminated optical film was produced in the same manner as in Comparative Example 1, except that the following polarizing plate roll body was used. Further, the optical compensation film is laminated on the side of the polarizing plate roll body where the protective film is not provided. The thickness of the laminated optical film thus obtained was 153 μm.

(Production of polarizing plate roll body)

After preparing the above-mentioned adhesive composition (see Example 1), the protective film (see Example 1) was sent out from the wound body after 30 minutes, and the single-sided coating was applied so as to have a thickness of 80 nm after drying. The composition is then applied to form an adhesive layer. Thereafter, the protective film on which the adhesive layer was formed was moved on one surface of the polarizing element sent from the wound body, and bonded by a roll machine, and passed in a gas atmosphere of 55 ° C for 6 minutes. The coiling was performed to produce a polarizing plate roll body.

The laminated optical film obtained in each of Examples 1 to 4 was subjected to the following evaluation. The evaluation results are summarized in Table 1.

Stripping

The laminated optical film obtained was cut to have a size of 25 mm in the absorption axis direction (longitudinal direction) of the polarizing element, and was 25 mm in the plane perpendicular to the absorption axis direction in the direction of the absorption axis, thereby obtaining a sample piece. The sample piece was immersed in hot water at 60 ° C for 5 hours. After the immersion, the peeling width (the interface between the polarizing element and the adjacent film) from the end side of the sample piece was measured with a vernier caliper.

2. Appearance (with or without crack points)

A sample piece having a size of 1000 mm × 1000 mm was cut out from the obtained laminated optical film. The sample piece was superposed on a polarizing plate (manufactured by Nitto Denko Corporation, trade name: NPF-SEG1224DU) placed on a black light under a fluorescent lamp. At this time, the absorption axis of the polarizing element of the sample piece is overlapped with the absorption axis of the other polarizing plates. The number of leaks (cracking defects) is counted in this state.

As is apparent from Table 1, it is possible to suppress the occurrence of crack defects by laminating using an adhesive composition containing an alumina colloid.

The laminated optical films obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were subjected to the following evaluations. The evaluation results are summarized in Table 2.

Stripping

A sample piece having a size of 1000 mm × 1000 mm was cut out from the obtained laminated optical film (Examples 1 to 3 only). The laminated optical film obtained in Comparative Examples 1 to 2 was directly used as a sample piece.

The above sample piece was immersed in hot water at 60 ° C for 5 hours. After the immersion, the peeling width (the interface between the polarizing element and the adjacent film) from the end side of the sample piece was measured with a vernier caliper.

2. Appearance (with or without foreign matter)

Ten pieces of samples having a size of 1000 nm × 1000 mm were cut out from the obtained laminated optical film (Examples 1 to 3 only). Ten laminated optical films of Comparative Examples 1 and 2 were separately prepared and used as sample pieces. The obtained sample piece was visually observed under a fluorescent lamp, and the number of foreign matter mixed between the polarizing element or the polarizing plate and the adjacent film was confirmed.

3. Optical properties

A sample piece having a size of 30 mm × 45 mm was cut out from the obtained laminated optical film, and the monomer transmittance and the degree of polarization were measured using an integrating sphere type transmittance measuring machine (manufactured by Murakami Color Research Co., Ltd., DOT-3C). The cutting of the sample piece was carried out in such a manner that the long side of the sample piece and the absorption axis of the polarizing element were at an angle of 45°.

The monomer transmittance was measured by providing a sample piece so that the protective film became the light source side of the measuring machine.

The degree of polarization is calculated based on the results obtained by measuring the parallel transmittance and the orthogonal transmittance. The parallel transmittance and the orthogonal transmittance were measured by separately preparing two sample pieces and providing two sample pieces so that the protective films overlap each other. Here, the absorption axis of one sample piece is arranged orthogonal to the absorption axis of the other sample piece.

As is clear from Table 2, it was confirmed that there were no foreign matters in Examples 1 to 3. On the other hand, it was confirmed that there were foreign substances in Comparative Examples 1 and 2. From this, it is understood that the lamination of the foreign matter can be suppressed by laminating the layers while carrying the layers. Further, the laminated optical film obtained in the examples was excellent in both the monomer transmittance and the degree of polarization. Further, Comparative Example 2 in which the polarizing element and the optical compensation film were laminated via the acrylic adhesive was more peeled than the other examples.

A liquid crystal panel was produced using the laminated optical film obtained in the following Reference Example 1 and Example 1, and the contrast was measured. Further, the laminated optical film of Reference Example 1, the method for producing the liquid crystal panel, and the method for measuring the contrast are as follows.

(Reference example 1)

A laminated optical film was obtained in the same manner as in Example 1 except that the optical compensation film described below was used and the optical compensation layer was not provided. The thickness of the laminated optical film thus obtained was 103 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 60 μm) obtained thereby was sandwiched in a tenter type stretcher and heated to 120. °C. While conveying the film in the longitudinal direction, the speed ratio (speed difference) of the left and right tenter is adjusted to 5% and extended in the lateral direction of the film, and also extended in the conveying direction of the film to obtain a strip having a thickness of 35 μm. Optical compensation film (stretch film).

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm, and the Nz coefficient was 1.55.

(Production of liquid crystal display device)

The liquid crystal cell is removed from a liquid crystal display device (a handheld game machine manufactured by Sony Corporation) equipped with a VA (Vertical Align) mode liquid crystal cell. Next, the obtained laminated optical film was attached to the visual side and the backlight side of the obtained liquid crystal cell via an acrylic adhesive (thickness: 20 μm). At this time, the optical compensation layer (optical compensation film) is attached so as to be on the liquid crystal cell side. Moreover, the absorption axes of the polarizing elements of the laminated optical films respectively disposed on both sides of the liquid crystal cell are laminated so as to be substantially orthogonal to each other. The liquid crystal panel was fabricated in this manner. A backlight unit of the original liquid crystal display device is mounted on the obtained liquid crystal panel to form a liquid crystal display device. Further, the configuration of the liquid crystal panel obtained and the axis angle of the absorption axis of the polarizing element on the visual side and the slow axis of the optical compensation film when the absorption axis of the polarizing element on the backlight side are used as a reference are shown in Table 3.

(measurement of contrast)

The liquid crystal display device was displayed with a white image and a black image, and was measured by the trade name "EZ Contrast 160D" manufactured by ELDIM.

The results of the liquid crystal panel of Example 1 are shown in Fig. 6, and the results of the liquid crystal panel of Reference Example 1 are shown in Fig. 7. Furthermore, the polar angle is 30. Azimuth angle 45. The contrast ratio is as follows: Example 1 is 107, and Reference Example 1 is 65. From these results, it is known that the contrast can be improved by providing an optical compensation layer.

[Example 5]

A laminated optical film was obtained in the same manner as in Example 1 except that the optical compensation film and the optical compensation layer described below were used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 120 μm) obtained thereby was sandwiched in a tenter type stretcher to obtain an Nz coefficient. In the manner of 1.60, the elongation temperature, the stretching ratio, the speed ratio, and the like were controlled to obtain a long optical compensation film (stretching film) having a thickness of 35 μm.

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

(production of optical compensation layer)

90 parts by weight of the nematic liquid crystal compound represented by the above chemical formula (1), 10 parts by weight of the optical agent represented by the above chemical formula (2), and 5 parts by weight of a photopolymerization initiator (Irgacure 907: manufactured by Ciba Specialty Chemicals Co., Ltd.) A portion and 300 parts by weight of methyl ethyl ketone were mixed until homogeneous to prepare a liquid crystal coating liquid. Next, the liquid crystal coating liquid was applied onto a long strip substrate (biaxially stretched PET film), heat-treated at 80 ° C for 3 minutes, and then irradiated with ultraviolet rays to carry out polymerization treatment, thereby forming a cholesterol which becomes an optical compensation layer on the substrate. Oriented to the cured layer. The thickness of the cholesterol alignment solidified layer was 1 μm, the phase difference Rth in the thickness direction was 40 nm, and the in-plane phase difference Re was substantially zero.

(Reference example 2)

The laminated optical film of Reference Example 2 was obtained in the same manner as in Comparative Example 1, except that the optical compensation layer of Example 5 and the polarizing plate roll of Example 4 and the optical compensation film described below were used. That is, each of the cut layers (films) was attached to obtain a laminated optical film. The thickness of the laminated optical film thus obtained was 155 μm.

(production of optical compensation film)

The norbornene-based resin film (manufactured by JSR, trade name: Arton, thickness: 120 μm) was subjected to melt extrusion molding, and the elongation temperature, the stretching ratio, the speed ratio, and the like were controlled so that the Nz coefficient became 1.60, and nx>ny> was obtained. A strip-shaped optical compensation film having a refractive index distribution of nz and a thickness of 35 μm. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

(Measurement of optical axis offset)

From the laminated optical film of Example 5, 50 sample pieces of a size of 100 mm × 100 mm were cut out. 50 sheets of the laminated optical film of Reference Example 2 were produced and used as a sample piece.

The angle of the optical axis of the sample piece was measured using the trade name "ROBRA-WPR" manufactured by the prince measuring machine (stock), and the optical axis shift was calculated.

Table 4 shows the average values of the optical axis shifts of the laminated optical films of Example 5 and Reference Example 2 and the standard deviation of 50 sample pieces.

As is clear from Table 4, by forming a laminated optical film by a Roll-to-Roll type, unevenness in optical axis shift can be suppressed.

Using the laminated optical film obtained in the above Example 5 and Reference Example 2, 50 liquid crystal panels were produced, and the transmittance and the orthogonal transmittance of the cells were measured, and the average value and standard deviation of the obtained values were calculated. . In addition, the manufacturing method of the liquid crystal display device is the same as that of Reference Example 1 except that the laminated optical film is used. For the liquid crystal panel of Example 5, the laminated optical film obtained from the same film roll is cut out to a specific size. In the liquid crystal panel of Example 2, the polarizing plate roll body, the optical compensation film, and the optical compensation layer were each cut out to a specific size, and the obtained laminated optical film was laminated. The method of measuring the monomer transmittance and the orthogonal transmittance is also the same as described above. The structure of the obtained liquid crystal panel and the axis of the absorption axis of the polarizing element on the visual side and the slow axis of the optical compensation film when the absorption axis of the polarizing element on the backlight side are used as the basic ratio are shown in Table 5.

Table 6 shows the average values and standard deviations of the monomer transmittance and the orthogonal transmittance of the liquid crystal display devices of Example 5 and Reference Example 2.

As can be seen from Table 6, the laminated optical film obtained by the same film roll was produced by a Roll-to-Roll type, whereby the average orthogonal transmittance was low and the light leakage was small. That is, it can be seen that the optical axis shift of the laminated optical film disposed on both sides of the liquid crystal cell can be suppressed. Further, as shown in Reference Example 2, when each layer is cut and bonded, it is necessary to provide a protective film between the polarizing element and the optical compensation film. Therefore, there is an abnormality due to scattering or refractive index. Further, it has been attempted to laminate the layers without a protective film between the polarizing element and the optical compensation film, but the polarizing plate is warped and cannot be bonded.

[Embodiment 6]

A laminated optical film was obtained in the same manner as in Example 5 except that the optical compensation film described below was used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 140 μm) obtained thereby was sandwiched in a tenter type stretching machine, and reached by an Nz coefficient. The elongation temperature, the stretching ratio, the speed ratio, and the like were controlled in a manner of 0.90 to obtain a long optical compensation film (stretching film) having a thickness of 35 μm.

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

[Embodiment 7]

A laminated optical film was obtained in the same manner as in Example 5 except that the optical compensation film described below was used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 140 μm) obtained thereby was sandwiched in a tenter type stretching machine, and reached by an Nz coefficient. In the manner of 1.20, the elongation temperature, the stretching ratio, the speed ratio, and the like were controlled to obtain a strip-shaped optical compensation film (stretching film) having a thickness of 35 μm.

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

[Embodiment 8]

A laminated optical film was obtained in the same manner as in Example 5 except that the optical compensation film described below was used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 140 μm) obtained thereby was sandwiched in a tenter type stretching machine, and reached by an Nz coefficient. In the manner of 1.40, the elongation temperature, the stretching ratio, the speed ratio, and the like were controlled to obtain a long optical compensation film (stretching film) having a thickness of 35 μm.

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

[Embodiment 9]

A laminated optical film was obtained in the same manner as in Example 5 except that the optical compensation film described below was used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 140 μm) obtained thereby was sandwiched in a tenter type stretching machine, and reached by an Nz coefficient. In the manner of 1.50, the elongation temperature, the stretching ratio, the speed ratio, and the like were controlled to obtain a strip-shaped optical compensation film (stretching film) having a thickness of 35 μm.

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

[Embodiment 10]

A laminated optical film was obtained in the same manner as in Example 5 except that the optical compensation film described below was used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 140 μm) obtained thereby was sandwiched in a tenter type stretching machine, and reached by an Nz coefficient. In the manner of 1.70, the elongation temperature, the stretching ratio, the speed ratio, and the like were controlled to obtain a long optical compensation film (stretching film) having a thickness of 35 μm.

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

[Example 11]

A laminated optical film was obtained in the same manner as in Example 5 except that the optical compensation film described below was used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 140 μm) obtained thereby was sandwiched in a tenter type stretching machine, and reached by an Nz coefficient. The elongation temperature, the stretching ratio, the speed ratio, and the like were controlled in a manner of 1.75 to obtain a long optical compensation film (stretching film) having a thickness of 35 μm.

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

[Embodiment 12]

A laminated optical film was obtained in the same manner as in Example 5 except that the optical compensation film described below was used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 140 μm) obtained thereby was sandwiched in a tenter type stretching machine, and reached by an Nz coefficient. In the manner of 1.80, the elongation temperature, the stretching ratio, the speed ratio, and the like were controlled to obtain a long optical compensation film (stretching film) having a thickness of 35 μm.

A clockwise 45 in the longitudinal direction is obtained in the above manner. A long strip of optical compensation film with a slow axis in the direction. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

[Example 13]

A laminated optical film was obtained in the same manner as in Example 5 except that the optical compensation film described below was used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 140 μm) obtained thereby was sandwiched in a tenter type stretching machine, and reached by an Nz coefficient. In the manner of 2.0, the elongation temperature, the stretching ratio, the speed ratio, and the like were controlled to obtain a strip-shaped optical compensation film (stretching film) having a thickness of 35 μm.

A clockwise 45 in the longitudinal direction is obtained in the above manner. A long strip of optical compensation film with a slow axis in the direction. The long optical compensation film was taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

(Reference Example 3)

A laminated optical film was obtained in the same manner as in Example 5 except that the optical compensation film described below was used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 140 μm) obtained thereby was sandwiched in a tenter type stretching machine, and reached by an Nz coefficient. The elongation temperature, the stretching ratio, the speed ratio, and the like were controlled in a manner of 0.70 to obtain a long optical compensation film (stretching film) having a thickness of 35 μm.

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

(Reference example 4)

A laminated optical film was obtained in the same manner as in Example 5 except that the optical compensation film described below was used. The thickness of the laminated optical film thus obtained was 115 μm.

(production of optical compensation film)

The norbornene-based resin (average molecular weight: 35,000, Tg: 140 ° C) was subjected to melt extrusion molding, and the unstretched film (thickness: 140 μm) obtained thereby was sandwiched in a tenter type stretching machine, and reached by an Nz coefficient. In the manner of 2.3, the elongation temperature, the stretching ratio, the speed ratio, and the like were controlled to obtain a long optical compensation film (stretching film) having a thickness of 35 μm.

An elongated optical compensation film having a slow axis in the clockwise direction of 45° in the longitudinal direction was obtained in the above manner. The long optical compensation film is taken up to form a wound body. Further, the in-plane retardation Re of the optical compensation film was 140 nm.

A liquid crystal display device was produced using the laminated optical film obtained in the above Examples 5 and 8 to 13, and the contrast was measured. The liquid crystal display device was manufactured by the same method as that of the above-described Example 5. The method of measuring the contrast is also the same as described above.

The results of the liquid crystal display devices of Examples 5 and 8 to 13 are shown in Fig. 8. From these results, it is understood that the contrast can be further improved by providing an optical compensation layer having a specific range of Nz coefficients.

[Industrial availability]

The laminated optical film of the present invention can be preferably applied to various image display devices, and can be preferably applied to a liquid crystal display device.

10. . . Laminated optical film

11. . . Polarizing element

12. . . Optical compensation film

13. . . Optical compensation layer

14. . . Subsequent layer

15. . . Protective film

BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a schematic cross-sectional view showing a laminated optical film according to a preferred embodiment of the present invention.

Fig. 2 is an exploded perspective view showing the optical axes of the respective layers constituting the laminated optical film shown in Fig. 1.

Fig. 3 is a schematic plan view showing an example of oblique extension.

Fig. 4 is a schematic view showing one of steps in an example of a method for producing a laminated optical film of the present invention.

Fig. 5 is a schematic view showing another step in an example of a method for producing a laminated optical film of the present invention. (a) of FIG. 5 is an explanatory view showing a bonding step of a laminate of a protective film, a polarizing element, and an optical compensation film, and a laminate in which an optical compensation layer is formed on a substrate. Fig. 5(b) is a schematic view showing a step of peeling off the substrate from the layered body obtained in the step of Fig. 5(a).

Fig. 6 is a contrast contour map showing the viewing angle dependence of the contrast of the liquid crystal panel using the laminated optical film of Example 1 of the present invention.

Fig. 7 is a contrast contour map showing the viewing angle dependence of the contrast of the liquid crystal panel using the laminated optical film of Reference Example 1.

Fig. 8 is a contrast contour map showing the viewing angle dependence of the contrast of the liquid crystal display device using the laminated optical films of Examples 5 and 8 to 13 of the present invention.

10. . . Laminated optical film

11. . . Polarizing element

12. . . Optical compensation film

13. . . Optical compensation layer

14. . . Subsequent layer

15. . . Protective film

Claims (14)

A laminated optical film which has a long strip shape and has a long-length optical compensation film having a long-length polarizing element having an absorption axis in the longitudinal direction and an index ellipsoid having a relationship of nx>ny≧nz, The refractive index ellipsoid has an optical compensation layer in a relationship of nx=ny>nz, and the slow axis of the optical compensation film forms an angle of 5 to 85° with the absorption axis of the polarizing element, wherein the polarizing element and the optical body are An adhesive layer is provided between the compensation films, and the adhesive layer is formed of an adhesive composition containing a polyvinyl alcohol-based resin, a crosslinking agent, and a metal compound colloid having an average particle diameter of 1 to 100 nm. The laminated optical film of claim 1, wherein the optical compensation film has an Nz coefficient of 0.9 to 2.0. The laminated optical film of claim 1 or 2 which is obtained by obliquely extending the optical compensation film described above. The laminated optical film of claim 1 or 2, wherein the optical compensation layer is a cholesterol alignment cured layer. The laminated optical film of claim 3, wherein the optical compensation layer is a cholesterol alignment cured layer. The laminated optical film of claim 1 or 2, which is formed into a roll shape. The laminated optical film of claim 3, which is formed into a roll shape. The laminated optical film of claim 4, which is formed into a roll shape. The laminated optical film of claim 5, which is formed into a roll shape. A method of manufacturing a laminated optical film, comprising: The long optical compensation film having the relationship of nx>ny≧nz and the polarizing element having an elongated shape and having an absorption axis in the longitudinal direction are respectively conveyed in the longitudinal direction, and the length of the optical compensation film is one side. a step of forming a laminated body by laminating the polarizing element on one side of the optical compensation film via the adhesive composition in such a manner that the direction thereof coincides with the longitudinal direction of the polarizing element; and an index of refraction of the optical compensation film side of the laminated body a step of an optical compensation layer having a relationship of nx=ny>nz; and the method for fabricating the laminated optical film is such that an angle between a slow axis of the optical compensation film and an absorption axis of the polarizing element is 5 to 85° The method includes laminating; wherein the adhesive layer is provided between the polarizing element and the optical compensation film, and the adhesive layer is composed of a polyvinyl alcohol-based resin, a crosslinking agent, and a metal compound colloid having an average particle diameter of 1 to 100 nm. The adhesive composition is formed. A method for producing a laminated optical film, comprising: optical compensation of a relationship of nx=ny>nz in a one-sided laminated index ellipsoid of a long optical compensation film having a relationship of nx>ny≧nz in an index ellipsoid a step of forming a layered body; and transporting the laminated body and the polarizing element having an absorption axis in the longitudinal direction in the longitudinal direction, and the length direction of the optical compensation film and the length of the polarizing element In a manner in which the directions are uniform, the polarizer is laminated on the side of the optical compensation film of the laminate via the adhesive composition And the step of fabricating the laminated optical film by laminating the slow axis of the optical compensation film and the absorption axis of the polarizing element to 5 to 85°; wherein the polarizing element and the optical An adhesive layer is provided between the compensation films, and the adhesive layer is formed of an adhesive composition containing a polyvinyl alcohol-based resin, a crosslinking agent, and a metal compound colloid having an average particle diameter of 1 to 100 nm. The method for producing a laminated optical film according to claim 10 or 11, further comprising the step of trimming or punching the laminated body after laminating the polarizing element, the optical compensation film, and the optical compensation layer. A laminated optical film produced by the production method according to any one of claims 10 to 12. A liquid crystal display device in which a laminated optical film according to any one of claims 1 to 5 and 13 is disposed on both sides of a liquid crystal cell, and the laminated optical film is obtained from the same film roll By.