JP2003004946A - Laminated optical film and method for manufacturing the same and liquid crystal display device using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated optical film excellent in workability and dimensional accuracy and in addition in reworkability (reproducing workability) after stuck to a liquid crystal cell used for a liquid crystal display device, a method for manufacturing the same and the liquid crystal display device using the same. SOLUTION: On a strip-shaped optical film (A), another strip-shaped optical film (B) with the width narrower than that of the optical film (A) is laminated in such a way that its longitudinal direction is parallel to the longitudinal direction of the optical film (A) and further the strip-shaped optical film (A) has side drop parts on both ends in the width direction so as to obtain a strip-shaped optical film laminated body. A rectangular strip-shaped optical film laminated body is obtained by cutting the obtained strip-shaped optical film laminated body in a direction vertical to the longitudinal direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical film used in a liquid crystal display device, which is excellent in reworkability after being attached to a liquid crystal cell, in addition to processing characteristics and dimensional accuracy, and a manufacturing method thereof. The present invention relates to a liquid crystal display device.

[0002]

2. Description of the Related Art An optical film represented by a polarizing plate (polarizing film) or a retardation film is important as an optical component constituting a liquid crystal display device. In a liquid crystal display device equipped with a backlight, in order to improve the brightness, a polarizing plate integrated type brightness enhancement film in which a polarizing plate and a brightness enhancement film are bonded together is often used. An optical film in which a plate and a brightness enhancement film are bonded together in advance is used.

Conventionally, an optical film for a liquid crystal display device such as a polarizing plate is processed so as to have a size slightly larger than the display screen of the liquid crystal display device, and a part of the light from the backlight contained in the optical film is processed. However, in order to prevent the phenomenon of stray light coming off from the edge of the film (stray light), the optical film is attached to the liquid crystal cell so as to cover the displayable range of the liquid crystal cell.

[0004]

However, an optical film composed of a laminate obtained by laminating a plurality of films is
Even if an attempt is made to make the sizes different as shown in FIG. 3, the dimensional accuracy cannot be obtained and the productivity cannot be improved by the conventional manufacturing method. Therefore, not only a single film but also two or more films can be used. At present, optical films made by laminating films are all processed to the same size.

In a small display device application such as a mobile phone, in order to fix a liquid crystal cell to which an optical film is bonded and a casing such as a backlight, the peripheral portion is adhered and fixed with double-sided tape or the like. Is often done. In this case, the double-sided tape is attached directly to the optical film part on the backlight side, but if there is a weak adhesive layer or other weak adhesive layer that is sticking each film together, the double-sided adhesive tape In the process of peeling the tape (module rework process), there is a problem that the tape is peeled off at the previous part. In particular, since the brightness enhancement film is often a multi-layered laminate, the adhesion is weak and such a problem is likely to occur.

Therefore, in order to solve the above-mentioned problems, the present invention laminates an optical film processed into a strip shape to have a predetermined width on a different type of optical film having a different width to form an optical film laminate. A laminated optical film used for a liquid crystal display device, which is excellent in reworkability after being attached to a liquid crystal cell, in addition to processing characteristics and dimensional accuracy by cutting the body into a product size, and a manufacturing method thereof. It is an object of the present invention to provide a liquid crystal display device using this.

[0007]

In order to achieve the above-mentioned object, a method for producing a laminated optical film of the present invention comprises a strip-shaped optical film (A) having a strip-shaped narrower than the optical film (A). The optical film (B) is laminated so that its longitudinal direction is parallel to the longitudinal direction of the optical film (A), and the strip-shaped optical film (A) has protruding portions at both ends in the width direction. Then, a strip-shaped optical film laminate is obtained, and the obtained strip-shaped optical film laminate is cut at a right angle to the longitudinal direction to obtain a rectangular optical film laminate.

Further, in the manufacturing method of the present invention, it is preferable that the optical film (A) is a polarizing plate and the optical film (B) is a brightness improving film.

Further, in the production method of the present invention, the optical film (A) is an optical film in which at least one retardation film or viewing angle compensation film is laminated on the opposite surface to be bonded to the optical film (B). It is preferably a film.

Further, in the manufacturing method of the present invention, the optical film (B) is preferably an optical film composed of a combination of a cholesteric liquid crystal and a λ / 4 plate.

Further, in the manufacturing method of the present invention, it is preferable that the optical film (B) is an optical film having a function of separating linearly polarized light by utilizing reflection at a multilayer interface.

Further, in the production method of the present invention, it is preferable that the optical film (A) and the optical film (B) are laminated via an adhesive.

Next, the laminated optical film of the present invention is a laminated optical film composed of a plurality of optical film laminates having different areas, and a protruding portion formed from at least one optical film constituting the laminate. And has
It is characterized by having the same cut surface on at least one side.

The laminated optical film of the present invention is a laminated optical film produced by the method described in any one of the above, which has a protruding portion formed from the optical film (A) and has the same cut surface. It is characterized by having at least one side.

Further, the liquid crystal display device of the present invention is characterized in that the above-mentioned laminated optical film is arranged on at least one side of the liquid crystal cell.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION A method for manufacturing a laminated optical film and a laminated optical film according to the present invention will be described with reference to FIGS. 1 to 4.

The laminated optical film obtained by the production method of the present invention is composed of a plurality of optical film laminates having different areas, as shown in FIG. 3, and has at least one layer of optical film constituting the laminate. The basic structure is a structure having a protruding portion formed from and having the same cut surface on at least one side. That is, the basic structure is such that the area of the optical film (A) is larger than the area (B) of the optical film, the optical film (A) 11 has protruding portions at both ends in the width direction, and has the same cut surface on at least one side. And

The length L of the laminated optical film depends on the application and is not particularly limited, but is usually 10
It is about 150 mm, preferably 25 to 60 mm. Also, the width D of the laminated optical film varies depending on the use,
Although not particularly limited, it is usually 10 to 150 m.
m, preferably 20 to 70 mm. Optical film
The width d ₁ of the optical film (B) laminated on (A) is set so that the optical film (A) has a protruding portion d ₂ of 1 to 4 mm at both ends in the width direction. If the width of the protruding portion d ₂ in the optical film (A) is less than 1 mm, the double-sided tape cannot be attached and, as a result, the surface light source cannot be fixed. On the other hand, if it exceeds 4 mm, the display range of the LCD screen is affected, and the display quality is degraded. The laminated optical film may be one or two of suitable optical layers other than the optical films (A) and (B).
It may be a laminate of more than one layer.

On the other hand, the laminated optical film obtained by the production of the present invention is a strip-shaped optical film as shown in FIG.
A rectangular optical film laminate obtained by cutting a strip-shaped optical film laminate 16 obtained by laminating (A) 14 and an optical film (B) 15 into a product size at right angles to the longitudinal direction. The cut laminated optical film can be used as a liquid crystal display element in the cut size,
Since the optical film (B) does not have the optical film (A) laminated on both end portions in the width direction, it has the protruding portions,
This protruding portion can be attached to the liquid crystal cell by using an adhesive means such as a double-sided tape.

In the present invention, the optical film (A) and the optical film (B) constituting the optical film laminate are not particularly limited as long as they can be used in a liquid crystal display device or the like, and are appropriately used. However, in order to achieve the object of the present invention, the optical film from the viewpoint of enhancing the adhesive force of the double-sided tape and improving the reworkability.
It is preferable to use a polarizing plate as (A) and a brightness enhancement film as optical film (B). Also,
As an optical film (A) according to the LCD to be used,
It is preferable to use a polarizing plate and at least one retardation film or a viewing angle compensation film laminated via an adhesive.

When a polarizing plate is used as the strip-shaped optical film (A) in the production method of the present invention, the optical film (A) is a synthetic resin film such as polyvinyl alcohol as shown in FIG. Protective films 3a and 3b such as triacetyl cellulose film (TAC) on both sides of the polarizer 4 in which iodine or dichroic dye is adsorbed and oriented
It is a structure in which And the strip-shaped polarizing plate
An adhesive layer 2a to be attached to a liquid crystal cell is provided on the outer surface of one of the TAC films, and the release film 1 is attached thereon.

The thickness of the above-mentioned adhesive layer is usually 10 to 35 μm.
m, and the thickness of the release film is usually about 15 to 100 μm.

Here, details of the polarizing plate used in the present invention will be described. The basic configuration of the polarizing plate is that a synthetic resin film is dyed, cross-linked, stretched, and dried, and one side or both sides of a polarizer made of a polyvinyl alcohol-based polarizing film containing a dichroic substance is appropriately bonded. A transparent protective film serving as a protective layer is adhered via a layer, for example, an adhesive layer composed of a vinyl alcohol polymer or the like.

As the polarizer (polarizing film), a film made of a suitable vinyl alcohol polymer such as polyvinyl alcohol or partially formalized polyvinyl alcohol is dyed with a dichroic substance such as iodine or a dichroic dye. Alternatively, suitable treatments such as stretching treatment and cross-linking treatment may be performed in an appropriate order or method, and appropriate ones that transmit linearly polarized light when natural light is incident can be used. It is preferable that it is excellent.
The thickness of the polarizer is not particularly limited, but 1 to
The thickness is generally 80 μm, and particularly preferably 2 to 40 μm.

An appropriate transparent film can be used as a protective film material which is a transparent protective layer provided on one side or both sides of the polarizer (polarizing film). Above all, a film made of a polymer having excellent transparency, mechanical strength, thermal stability, moisture shielding property and the like is preferably used. Examples of the polymer include acetate resin such as triacetyl cellulose, polyester resin, polyether sulfone resin, polycarbonate resin, polynorbornene resin, polyamide resin, polyimide resin, polyolefin resin, acrylic resin. However, the present invention is not limited to this. Although the thickness of the transparent protective film is arbitrary, it is generally 500 μm or less, preferably 5 to 300 μm for the purpose of thinning the polarizing plate. When transparent protective films are provided on both sides of the polarizing film, transparent protective films made of different polymers may be used on the front and back sides.

The transparent protective film used for the protective layer is
As long as the object of the present invention is not impaired, a hard coat treatment, an antireflection treatment, a treatment for the purpose of preventing sticking, diffusion or antiglare, or the like may be applied. The hard coat treatment is carried out for the purpose of preventing scratches on the surface of the polarizing plate. For example, a cured coating excellent in hardness and slipperiness with a suitable ultraviolet curable resin such as silicone is applied to the surface of the transparent protective film. It can be formed by a method of adding to.

On the other hand, the antireflection treatment is carried out for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the prior art. In addition, anti-sticking is performed for the purpose of preventing adhesion with an adjacent layer, and anti-glare treatment is performed for the purpose of preventing external light from being reflected on the surface of the polarizing plate and hindering visual recognition of light transmitted through the polarizing plate. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a surface roughening method such as a sandblasting method or an embossing method or a method of blending transparent fine particles.

Examples of the transparent fine particles include silica and alumina having an average particle diameter of 0.5 to 20 μm, titania and zirconia, tin oxide and indium oxide, cadmium oxide and antimony oxide. Fine particles may be used, and organic fine particles composed of crosslinked or non-crosslinked polymer particles may be used. The amount of the transparent fine particles used is generally 2 to 70 parts by mass, particularly 5 to 50 parts by mass, per 100 parts by mass of the transparent resin.

The antiglare layer containing transparent fine particles can be provided as the transparent protective layer itself or as a coating layer on the surface of the transparent protective layer. The anti-glare layer is
It may also serve as a diffusion layer (viewing angle compensation function or the like) for diffusing the light transmitted through the polarizing plate and expanding the viewing angle. The antireflection layer, the sticking prevention layer, the diffusion layer, the antiglare layer, and the like described above can be provided as an optical layer formed of a sheet provided with these layers, separately from the transparent protective layer.

The adhesion treatment between the above-mentioned polarizer (polarizing film) and the transparent protective film as a protective layer is not particularly limited, but for example, an adhesive made of a vinyl alcohol-based polymer, boric acid or boronic acid is used. It can be carried out through an adhesive or the like comprising at least a water-soluble cross-linking agent of a vinyl alcohol polymer such as sand, glutaraldehyde, melamine and oxalic acid. Such an adhesive layer can be formed as a coating / drying layer of an aqueous solution, but other additives and a catalyst such as an acid can be blended, if necessary, in the preparation of the aqueous solution.

In the manufacturing method of the present invention, when a laminated film of a polarizing plate and a retardation film or a viewing angle compensation film is used as the strip-shaped optical film (A), the optical film (A) is shown in FIG. As an example thereof, it has a structure in which a retardation film 7 or a viewing angle compensation film made of a resin film obtained by stretch-molding polycarbonate or the like and a polarizing plate 5 are bonded together via an adhesive 6b. In the strip-shaped laminated film, the pressure-sensitive adhesive layer 6a to be bonded to the liquid crystal cell is provided on the outer surface of the retardation film or the viewing angle compensation film, and the release film is bonded thereto as necessary.

Further, the optical film (A) and the optical film
The laminate with (B) has a structure in which a cholesteric liquid crystal layer 10 and a λ / 4 plate 9 are bonded together via an adhesive layer 8b as shown in FIG. λ / 4
The plate 9 is laminated via the adhesive layer 8a.

The thickness of the above retardation film is usually 5 to 5.
About 150 μm, the thickness of the viewing angle compensation film is usually 5
It is about 250 μm.

The thickness of the brightness enhancement film composed of the combination of the cholesteric liquid crystal layer and the λ / 4 plate is usually about 30 to 300 μm.

The thickness of the above-mentioned adhesive layer is usually 10 to 3
About 5 μm, the thickness of the release film is usually 15 to 100 μm
It is about m.

Specific examples of the retardation film (retardation film) used in the present invention include a film made of a suitable polymer such as polycarbonate, polyvinyl alcohol, polystyrene, polymethylmethacrylate, polypropylene or other polyolefin, polyarylate or polyamide. Examples of the birefringent film obtained by stretching the film, an alignment film of a liquid crystal polymer, and an alignment layer of a liquid crystal polymer supported by a film. Further, as the inclined orientation film, for example, a heat-shrinkable film is adhered to a polymer film and under the action of the shrinkage force by heating,
Examples thereof include those obtained by subjecting a polymer film to stretching treatment and / or shrinkage treatment, and those obtained by obliquely aligning a liquid crystal polymer.

The retardation plate is used for converting linearly polarized light into elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light into linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, changing linearly polarized light to elliptically polarized light or circularly polarized light,
A so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate for converting elliptically polarized light or circularly polarized light into linearly polarized light. A half-wave plate (also called a λ / 2 plate) is usually
It is used when changing the polarization direction of linearly polarized light.

As the viewing angle compensation film used in the present invention, a triacetyl cellulose film coated with a discotic liquid crystal or a retardation plate is used. In the ordinary retardation plate, while a polymer film having birefringence uniaxially stretched in its plane direction is used, the retardation plate used as the viewing angle compensation film,
Bi-directional biaxially oriented polymer film stretched biaxially in the plane direction, or bi-directionally oriented polymer film oriented uniaxially in the plane direction and also in the thickness direction, such as a tilt-oriented polymer film with controlled refractive index in the thickness direction. A stretched film or the like is used. As the tilt-oriented film, as described above, for example, a heat-shrinkable film is adhered to a polymer film, and the polymer film is stretched and / or shrunk under the action of the shrinkage force by heating, or a liquid crystal polymer. Examples include those that are obliquely oriented. As the raw material polymer for the retardation plate, the same polymer as the polymer described for the retardation plate is used.

The viewing angle compensating film is a film for widening the viewing angle so that the image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction, not perpendicular to the screen.

The brightness enhancement film used in the present invention is, for example, a multilayer thin film of a dielectric or a multilayer stack of thin films having different refractive index anisotropies, which transmits linearly polarized light having a predetermined polarization axis and transmits other light. Represents a property of reflecting light, such as a cholesteric liquid crystal layer, particularly an oriented film of a cholesteric liquid crystal polymer or a film obtained by supporting the oriented liquid crystal layer on a film substrate, and reflects either left-handed or right-handed circularly polarized light. Therefore, other appropriate light such as a material exhibiting a property of transmitting other light can be used.

The brightness enhancement film preferably used is a brightness enhancement film comprising a cholesteric liquid crystal layer and a λ / 4 plate, wherein the λ / 4 plate is formed from a liquid crystal layer, and the alignment state of liquid crystals in the liquid crystal layer. Is non-uniform and there is an interface where light is refracted. Alternatively, those having a linearly polarized light separating function utilizing reflection at the multilayer interface are preferable.

Therefore, in the brightness enhancement film of the type which transmits the linearly polarized light of the above-mentioned predetermined polarization axis, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned to suppress the absorption loss by the polarizing plate. It can be efficiently transmitted. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light like a cholesteric liquid crystal layer, it can be directly incident on a polarizer, but from the viewpoint of suppressing absorption loss, the transmitted circularly polarized light is linearly polarized through a retardation plate. It is preferable that the light is incident on the polarizing plate. By using a ¼ wavelength plate as the retardation plate, circularly polarized light can be converted into linearly polarized light.

A retardation plate that functions as a quarter-wave plate in a wide wavelength range such as a visible light region is a retardation layer that functions as a quarter-wave plate for monochromatic light such as light having a wavelength of 550 nm. It can be obtained by a method of superimposing a retardation layer showing the retardation characteristic of, for example, a retardation layer functioning as a half-wave plate. Therefore, the retardation plate disposed between the polarizing plate and the brightness enhancement film may be composed of one layer or two or more retardation layers.

As for the cholesteric liquid crystal layer,
By combining two or more layers having different reflection wavelengths to form an arrangement structure in which two or more layers are superposed, it is possible to obtain one that reflects circularly polarized light in a wide wavelength range such as a visible light range.
Based on this, it is possible to obtain transmitted circularly polarized light in a wide wavelength range.

The above-mentioned strip-shaped optical film (A) is usually supplied by processing a roll of an optical film (raw material) wound in a roll having a width of 0.3 to 1.5 m into a strip. .
When a laminated film of a polarizing plate and a retardation film or a viewing angle compensation film is used as the optical film (A), it is laminated in the original state and then processed into a strip shape. The size of the strip is appropriately determined depending on the application of the optical film and is not particularly limited, but the width is usually 10 to 150.
mm, the length is 100 to 350 mm.

Further, the above strip-shaped optical film (B) is
Usually, an optical film roll (original material) wound in a roll shape having a width of 0.3 to 1.5 m is processed into a strip shape and supplied. The size of the strip is appropriately determined according to the application of the optical film and is not particularly limited, but usually the width is 6 to 150 mm and the length is 100 to 350.
mm. Thereby, when the optical film (B) is laminated on the optical film (A), a protruding portion for adhering to the liquid crystal cell can be provided on the optical film (A). It is possible to prevent peeling of a layer having a weak adhesive force in the module rework step as compared with the case where the layer is attached to a liquid crystal cell.

Next, a method of manufacturing the laminated optical film in this embodiment will be described with reference to FIG.

In the step of processing a strip-shaped optical film (cutting to a constant length), for example, the film is sent out from a raw roll of the optical film at a constant feed length (pitch), and this is cut by a cutter or the like. Using a strip-shaped optical film (A), a strip-shaped optical film (B)
Cut out.

Next, as shown in FIG. 4, a fixed-length strip-shaped optical film (A) 14 (for example, a polarizing plate or a laminated film of a polarizing film and a retardation film or a viewing angle compensation film) and a fixed length. The strip-shaped optical film (B) 15 (for example, a brightness enhancement film) is attached. In this process,
Optical film with an adhesive layer on the optical film (A)
By pressing (B) on top of each other,
A strip-shaped laminate 16 of (A) and the optical film (B) is formed. At that time, in order to improve the dimensional accuracy, it is preferable to sequentially bond the strips in the longitudinal direction (the direction of the arrow in FIG. 4). A reference bar is provided in the longitudinal direction of each strip, and each reference bar has a length of d ₂ . Set it so that it deviates by a certain amount.

Thereafter, as shown in FIG. 4, the strip-shaped optical film laminate 16 is cut into a predetermined size at right angles to the longitudinal direction in accordance with the product size to form a rectangular optical film laminate. Cut out the body.

In the production method of the present invention, when the optical film (A) such as a polarizing plate and the optical film (B) such as a brightness enhancement film are laminated, or when the polarizing plate and the retardation film or the viewing angle compensation film are laminated. In this case, it is possible to laminate using an appropriate adhesive means, but it is preferable to laminate with an adhesive in order to relieve the stress during bonding, the stress due to the dimensional change of the film and the like.

The pressure-sensitive adhesive layer can be formed of a suitable pressure-sensitive adhesive such as an acrylic resin that is conventionally used. In particular, in terms of prevention of foaming phenomenon and peeling phenomenon due to moisture absorption, deterioration of optical characteristics due to thermal expansion difference and the like, prevention of warpage of liquid crystal cells, and further formation of a liquid crystal display device having high quality and excellent durability, the moisture absorption rate is high. The adhesive layer is preferably low and has excellent heat resistance. It is also possible to form an adhesive layer containing fine particles and exhibiting light diffusivity. The adhesive layer may be provided on a required surface as needed.

When the pressure-sensitive adhesive layer provided on the polarizing plate or the optical member is exposed on the surface, it is preferable to temporarily cover the pressure-sensitive adhesive layer with a separator for the purpose of preventing contamination until the pressure-sensitive adhesive layer is put into practical use. The separator is formed by a method in which a suitable thin sheet conforming to the above-mentioned transparent protective film or the like is provided with a release coat using a suitable release agent such as silicone-based or long-chain alkyl-based, fluorine-based or molybdenum sulfide as necessary. be able to.

Each layer such as the polarizing film and the transparent protective film forming the polarizing plate and the optical member, the optical layer and the adhesive layer is, for example, a salicylic acid ester compound, a benzophenone compound, a benzotriazole compound or a cyanoacrylate compound. It may be one having an ultraviolet absorbing ability by an appropriate method such as a method of treating with an ultraviolet absorber such as a compound or a nickel complex salt compound.

The laminated optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device, and is a transmissive type or a semi-transmissive type in which the laminated optical film of the present invention is arranged on one side of a liquid crystal cell. Can be preferably used for the liquid crystal display device. The liquid crystal cell forming the liquid crystal display device is arbitrary, and an appropriate type such as an active matrix drive type represented by a thin film transistor type, a simple matrix drive type represented by a twist nematic type or a super twist nematic type, etc. The liquid crystal cell may be used.

When polarizing plates and optical members are provided on both sides of the liquid crystal cell, they may be the same or different. Further, when forming the liquid crystal display device, one or two or more layers can be arranged at appropriate positions with appropriate components such as a prism array sheet, a lens array sheet, a light diffusion plate, and a backlight.

[0057]

EXAMPLES The present invention will be described in more detail below with reference to examples.

Example 1 A polyvinyl alcohol film having a thickness of 75 μm was immersed in a dyeing bath (30 ° C.) containing iodine and potassium iodide, subjected to a dyeing treatment and a stretching treatment of 3 times, and then boric acid. In an acidic bath (60 ° C.) to which potassium iodide was added, a total of 5 times of stretching and crosslinking treatment were performed, and the film was dried at 50 ° C. for 5 minutes to obtain a polarizing film.
A polycarbonate film having a thickness of 50 μm was adhered to both sides of the polarizing film with an adhesive and dried to prepare a polarizing plate.

As the optical compensation layer, a polycarbonate film having a thickness of 50 μm similar to that used in the protective layer was stretched at 150 ° C. by 2.5% to prepare a retardation film. A polarizing plate with a retardation film, in which an acrylic adhesive is formed to a thickness of 25 μm on both sides, and the absorption axis of the polarizing plate and the slow axis of the retardation plate are 45 degrees through the adhesive. Was produced.

Separately from the above, an alignment film of PVA with a thickness of 0.1 μm was formed on a TAC film with a thickness of 80 μm, and the surface of this alignment film was rubbed in a certain direction and then subjected to a rubbing treatment. A nematic liquid crystal polymer at -210 ° C was applied with a thickness of about 0.5 µm and a front phase difference of 130 nm using a gravure coater, and oriented at 150 ° C for 1 minute to prepare a λ / 4 plate. Another 50 μm thick TAC
An alignment film of PVA with a thickness of 0.1 μm is formed on the film, and after rubbing treatment, a cholesteric liquid crystal polymer is selectively reflected at central wavelengths of 400 nm, 550 nm and 700 nm.
3 layers were sequentially formed and oriented on the orientation film. The thickness of each layer was 3 μm. Next, a polycarbonate λ / 4 plate (front phase difference 130 nm) was attached onto the cholesteric liquid crystal layer with an acrylic pressure-sensitive adhesive having a thickness of 25 μm to obtain a brightness enhancement film.

Next, from the polarizing plate with a retardation film produced by the above method, the absorption axis of the polarizing plate was set to 170 in the longitudinal direction.
It was cut out in a strip shape to have a size of mm × 40 mm. Similarly, 170mm x 35m from the brightness enhancement film
It was cut into strips to have a size of m. The brightness enhancement film cut out in strips is placed on the polarizing plate cut out in strips with an acrylic adhesive and a lateral gap of 2.5 mm each is made using a laminating machine in the longitudinal direction. Then, the strip-shaped optical film laminates were produced. The axial angle was set to be 90 degrees with the absorption axis of the polarizing plate, and the brightness enhancement film was bonded so that the optical axis thereof was aligned with it. The obtained strips were cut with a guillotine cutter at intervals of 50 mm to obtain three optical film laminates (No. 1 to 3). Product size (Film (A): Vertical 50 mm x Horizontal 40 mm, Film (B): Vertical 5
0 mm x width 35 mm, protrusions 2.5 mm each).

The size of each of the three optical film laminates obtained was measured with a digital caliper, and the width average, length average, and dispersity (σ) were obtained. The results are shown in Table 1.
Shown in. In addition, visual defects were visually confirmed and evaluated, but no abnormality was found.

[0063]

[Table 1] Width of laminated film Length of laminated film Width of protruding portion (mm) (mm) Left (mm) Right (mm) No. 1 40.10 49.95 2.37 2.70 No. 2 40.14 49.96 2.33 2.60 No. 3 40.09 49.92 2.40 2.58 Average 40.11 49.94 2.37 2.62 σ 0.02 0.02 0.03 0.05

As is clear from Table 1, the optical film laminate produced by the production method of the present invention is excellent in dimensional accuracy.

[0065]

As described above, according to the method for producing a laminated optical film of the present invention, first, the strip-shaped optical film (A) and the strip-shaped optical film (B) are cut out from the original roll and The films are laminated to form a strip-shaped optical film laminate, and then this strip-shaped optical film laminate is cut into a size to cut out a rectangular optical film laminate. As a result, the process that was conventionally performed, that is,
Since it is possible to form an optical film laminate of a predetermined shape at the same time as processing into a product size without taking a step of laminating optical films cut to size, it is excellent in productivity. Moreover, since the product is cut out in the final step, it can be cut without waste and the dimensional accuracy of the laminated optical film is excellent.

Further, according to the manufacturing method of the present invention, an optical film processed into a strip shape so as to have a predetermined width size.
Optical films (B) processed into strips having different width sizes are bonded to (A) to form a laminate, and the laminate is cut into product sizes. Therefore, the laminated optical film of the present invention, since the optical film has a protruding portion,
By providing an adhesive layer (for example, by using a double-sided tape) on the portion, the liquid crystal cell can be accurately attached, light leakage of the liquid crystal display device can be suppressed, and peeling in the module rework process can be prevented. It can be prevented. Furthermore, by using the laminated optical film of the present invention in a liquid crystal display device, it is possible to contribute to making the liquid crystal display device thinner and lighter. Therefore, its industrial value is great.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing a configuration using a polarizing plate as an optical film (A).

FIG. 2 is a cross-sectional view showing a configuration using a polarizing plate with a retardation film as an optical film (A).

3 (a) is a front view and FIG. 3 (b) is a sectional view of the laminated optical film of the present invention.

FIG. 4 is a conceptual diagram showing a configuration of a manufacturing process of a laminate of the optical film (A) and the optical film (B).

[Explanation of symbols]

1 Release Film 2a Adhesives 3a, 3b Protective Film 4 Polarizer 5 Polarizing Plates 6a, 6b Adhesive 7 Retardation Films 8a, 8b Adhesive 9 λ / 4 Plate 10 Cholesteric Liquid Crystal Layer 11 Optical Film (A) 12 Optical Film (B) 13 laminated optical film 14 strip-shaped optical film (A) 15 strip-shaped optical film (B) 16 strip-shaped optical film laminate 17 cut-out line for cutting out the optical film laminate from the strip-shaped optical film laminate

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shoji Sugiura             1-2 1-2 Shimohozumi, Ibaraki City, Osaka Prefecture Nitto             Electric Works Co., Ltd. F-term (reference) 2H049 BA02 BA05 BA06 BA07 BA42                       BB03 BB33 BB43 BB51 BB54                       BB65 BC13 BC14 BC22                 2H091 FA08X FA08Z FA11X FA11Z                       FA14Z FC16 FD06 FD16                       LA09

Claims (9)

[Claims] 1. A strip-shaped optical film (B) having a width narrower than that of the optical film (A).
The strip-shaped optical film (A) is laminated so that its longitudinal direction is parallel to the longitudinal direction of the optical film (A) and the strip-shaped optical film (A) has protruding portions at both ends in the width direction. A method for producing a laminated optical film, comprising obtaining a film laminate, and cutting the obtained strip-shaped optical film laminate at a right angle to a longitudinal direction thereof to obtain a rectangular optical film laminate. 2. The method for producing a laminated optical film according to claim 1, wherein the optical film (A) is a polarizing plate and the optical film (B) is a brightness enhancement film. 3. The optical film (A) is an optical film (B).
The method for producing a laminated optical film according to claim 1 or 2, which is an optical film in which at least one retardation film or a viewing angle compensation film is laminated on the opposite surface to be laminated with. 4. The method for producing a laminated optical film according to claim 1, wherein the optical film (B) is an optical film composed of a combination of a cholesteric liquid crystal and a λ / 4 plate. 5. The method for producing a laminated optical film according to claim 1, wherein the optical film (B) is an optical film having a linearly polarized light separating function utilizing reflection at a multilayer interface. 6. An optical film (A) and an optical film (B)
The method for producing a laminated optical film according to claim 1, wherein the film is laminated via an adhesive. 7. A laminated optical film comprising a plurality of optical film laminates having different areas, having a protruding portion formed from at least one layer of optical film constituting the laminate, and having the same cut surface. A laminated optical film having at least one side. 8. A laminated optical film produced by the method according to claim 1, wherein the laminated optical film has a protruding portion formed from the optical film (A), and has the same cut surface on at least one side. A laminated optical film having. 9. A liquid crystal display device, wherein the laminated optical film according to claim 7 or 8 is arranged on at least one side of a liquid crystal cell.