JP2003043262A - Method for manufacturing laminated optical film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a layered optical film having excellent reworking properties after adhered to a liquid crystal cell as well as excellent processing characteristics and dimensional accuracy. SOLUTION: In the method for manufacturing a layered optical film consisting of a layered body of a plurality of optical films with different areas, an optical film (B) having a different function from that of an optical film (A) is laminated on at least one face of the optical film (A) to form a layered body, and then the body is cut by using punching dies having different levels to obtain the layered optical film.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a laminated optical film used in a liquid crystal display device, which is excellent in processing characteristics and dimensional accuracy as well as in reworkability after being attached to a liquid crystal cell, and a method for producing the same. And a liquid crystal display device using the same.

[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 the plate and the 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.

However, even if an optical film composed of a laminated body in which a plurality of films are laminated has different sizes as shown in FIG. 3, dimensional accuracy cannot be obtained by the conventional manufacturing method, resulting in productivity. Since it cannot be raised, not only a single film but also an optical film obtained by laminating two or more films are all processed into 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.

[0006]

DISCLOSURE OF THE INVENTION According to the present invention, an optical film (B) having a function different from that of the optical film (A) is laminated on the optical film (A), and the obtained optical film laminate is punched with a step. In addition to processing characteristics and dimensional accuracy, it is reworked after being attached to the liquid crystal cell (reproduction work)
An object is to provide a method for producing a laminated optical film having excellent properties.

[0007]

In order to solve the above-mentioned problems, the method for producing a laminated optical film of the present invention is a method for producing a laminated optical film comprising a laminate of a plurality of optical films having different areas. An optical film (B) having a function different from that of the optical film (A) is laminated on at least one surface of the film (A) to form a laminated body, and then the laminated body is cut with a punching blade die having a step. It is characterized by

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.

In the production method of the present invention, the optical film (A) is an optical film formed by laminating at least one retardation film or a viewing angle compensation film on the opposite surface of 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.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION A method for producing a laminated optical film and a laminated optical film according to the present invention will be described below with reference to FIGS. 1 to 6.

The laminated optical film obtained by the manufacturing method of the present invention has a planar structure shown in FIG. 3 and a cross-sectional structure shown in FIG. 4, and the optical film (A) 11 has an area of the optical film (B) 12. Larger than the area of the optical film (A) 11
Is a basic structure having protruding portions at both ends in at least one direction. The protruding portions may be located at both ends in one direction as shown in FIG. 3A or at both ends in two directions as shown in FIG. 3B. By providing such a protruding portion, an adhesive layer can be provided at that portion (for example, by using a double-sided tape) and the liquid crystal cell can be accurately attached. Therefore, the brightness enhancement film, which is a multilayer laminate, is attached to the liquid crystal cell. It is possible to prevent peeling of the layer having weak adhesion in the module rework process as compared with the case where the layers are combined.

The length L of the laminated optical film depends on the application and is not particularly limited, but is usually 10
~ 150 mm. Also, the width D of the laminated optical film
Also, although it depends on the application and is not particularly limited, it is usually 10 to 150 mm, preferably 20 to 70 m.
m. Optical film laminated on optical film (A)
The width d ₁ of (B) is usually 10 to 150 mm, and the optical film (A) has protruding portions d ₂ of 1 to 4 mm at both ends in at least one 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 the surface light source cannot be fixed. If it exceeds 4 mm, the display range of the LCD screen is displayed. It will deteriorate the quality.

In the above basic structure, an optical film
The thickness d ₅ of (A) is 30 to 500 μm, preferably 50.
˜300 μm, and the thickness d of the optical film (B)
₃ is ₃₀ to 300 μm, preferably 50 to 200 μm, and it is desirable to have a relationship of d ₃ ≦ d ₅ . The thickness d _{4 of the} adhesive layer is 10 to 35 μm, preferably 1
It is 5 to 25 μm. In the optical film laminate of the present invention, the optical film (A) and the optical film
In addition to (B), one or two or more suitable optical layers may be laminated.

On the other hand, as shown in FIG. 5, the laminated optical film obtained by the production of the present invention is an optical film (A) having a predetermined size, and an optical film (B) having a function different from that of the optical film (A). The optical film laminated body in which (1) is laminated is cut by a punching blade die having a step. The cut laminated optical film can be used as a liquid crystal display element in the cut size, and is composed of only the optical film (A) in which the optical film (B) is not laminated at both ends in at least one direction. Since the protruding portion is provided, the 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 (A) is used in order to increase the adhesion of the double-sided tape and improve the reworkability.
It is preferable to use a polarizing plate as the above and a brightness enhancement film as the optical film (B). Further, it is preferable to use, as the optical film (A), a laminate of a polarizing plate and at least one retardation film or a viewing angle compensating film via an adhesive, depending on the LCD to be used.

In the manufacturing method of the present invention, an optical film
When using a polarizing plate as (A), the optical film (A)
As shown in the example in FIG. 1, is adsorbed iodine or dichroic dye on a synthetic resin film such as polyvinyl alcohol,
This is a structure in which protective films 3a and 3b such as a triacetyl cellulose film (TAC) are attached to both sides of the oriented polarizer 4. In this polarizing plate, an adhesive layer 2a to be attached to the liquid crystal cell is provided on the outer surface of the TAC film, and the release film 1 is attached to the adhesive layer 2a.

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

The basic constitution of the polarizing plate used in the present invention is
Dyeing, cross-linking, stretching, and drying of a synthetic resin film, one side or both sides of a polarizer made of a polyvinyl alcohol-based polarizing film containing a dichroic substance, an appropriate adhesive layer, for example, from a vinyl alcohol-based polymer or the like. A transparent protective film serving as a protective layer is adhered via the adhesive layer.

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 and 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 the 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 conventional method. 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 anti-glare 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 adhesive treatment between the above-mentioned polarizer (polarizing film) and the transparent protective film which is the protective layer is not particularly limited, but for example, an adhesive made of a vinyl alcohol polymer, boric acid or boric 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 production 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 optical film (A), the optical film (A) is shown in FIG. As shown, a retardation film 7 or a viewing angle compensation film made of a stretched resin film of polycarbonate or the like and a polarizing plate 5 are provided as an adhesive 6b.
It is a structure that is bonded via. The laminated film is provided with an adhesive layer 6a to be attached to the liquid crystal cell on the outer surface of the retardation plate or the viewing angle compensation film, and a release film is attached to the adhesive layer 6a as necessary. On the outer surface of the optical film (B), an adhesive layer 8a to be attached to the optical film (A) is provided.

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 1
About 50 μm, the thickness of the viewing angle compensation film is usually 5 to 25
It is about 0 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 30.
It is about 300 μm.

The thickness of the adhesive layer is usually 10 to 35 μm.
The thickness of the release film is usually about 15 to 100 μm.

Specific examples of the retardation film (retardation film) used in the present invention include films made of polycarbonate, polyvinyl alcohol, polystyrene, polymethylmethacrylate, polypropylene and other polyolefins, and appropriate polymers such as polyarylate and 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 film obtained by adhering a heat-shrinkable film to a polymer film and subjecting the polymer film to stretching treatment and / or shrinking treatment under the action of the shrinkage force by heating, or a liquid crystal polymer which is obliquely oriented. And so on.

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. Change 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,
A bidirectional birefringent polymer film that is biaxially stretched in the plane direction, or a bidirectional polymer film that is uniaxially stretched in the plane direction and is also oriented in the thickness direction. A stretched film or the like is used. As the tilted oriented film, as described above, for example, a polymer film is adhered to a heat-shrinkable film and stretched and / or shrunk to the polymer film under the action of the shrinkage force by heating, or a liquid crystal polymer is slanted. Examples include oriented materials. 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 compensation 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 laminate 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.

A 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 having the predetermined polarization axis, the transmitted light is directly incident on the polarizing plate with the polarization axis aligned, thereby suppressing 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.

Regarding 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 optical film (A) is, for example, as shown in FIG. 4, an optical film roll (original fabric) wound into a roll having a width of 0.3 to 15 m and processed into a predetermined size. Or supplied as is. 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), a film having a predetermined size is supplied after being laminated. The size of the film is appropriately determined according to the use of the optical film,
Although not particularly limited, the width D ₂ is usually 10
It is 15 mm and the length L _{2 is} 100 to 350 mm. And, in many cases, those optical axes, that is, the absorption axis of the polarizing plate, and the slow axis of the retardation film or the viewing angle compensation film extend in the stretching direction of the raw material used, and depending on the stretching method, the longitudinal direction thereof Parallel or orthogonal.

As the optical film (B), one having substantially the same size as the optical film (A) is used.

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

In the optical film processing (fixed length cutting) step, 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 cutting means such as a cutter. Then, the optical film (A) and the optical film (B) having a predetermined size are cut out.

Next, the optical film (A) (for example, a polarizing plate,
Alternatively, a laminated film of a polarizing film and a retardation film or a viewing angle compensation film) and an optical film (B) (for example, a brightness enhancement film) are attached. In this step, the optical film (B) is superposed on the optical film (A) via the adhesive layer using a bonding roll to form a laminate of the optical film (A) and the optical film (B). . At that time, in order to improve the dimensional accuracy, it is preferable to bond the film along the roll at a constant speed from the end.

When laminating the above optical films, the laminating speed, the laminating temperature, the laminating conditions such as the laminating roll are not particularly limited, but in general, the end portions are It is preferable to use a roll having a width wider than that of the optical film to be bonded, from the viewpoint of bonding without air bubbles and improving bonding axis accuracy.

Thereafter, as shown in FIGS. 5 to 6, the laminated laminate 14 is cut using a punching blade die 15 having a step according to the product size, and a rectangular laminated optical film is cut out. The blade length of the punching blade type is appropriately determined according to the thickness of the film to be cut and is not particularly limited, but normally the length of the cutting blade 16a (long blade) is 5
0 to 500 μm, the length of the cutting blade 16b (short blade) is 30 to
It is 300 μm, and it is preferable that the blade length difference between the long blade and the short blade is substantially equal to the thickness of the optical film (A) for accurate cutting.

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, they may be laminated using an appropriate adhesive means such as an adhesive layer. However, in order to relieve the stress at the time of sticking and the stress due to the change in the film dimensions, it is preferable to laminate with an adhesive. The same applies when a polarizing plate and a retardation film or a viewing angle compensation film are laminated.

The pressure-sensitive adhesive layer can be formed of a suitable pressure-sensitive adhesive such as acrylic based on the conventional one. 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 pressure-sensitive adhesive layer may be provided on a necessary surface as necessary. For example, if a protective layer of a polarizing plate comprising a polarizer and a protective layer is mentioned, a pressure-sensitive adhesive layer may be provided on one side or both sides of the protective layer, if necessary. Should be provided.

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. The laminated optical film of the present invention is disposed on one side of a liquid crystal cell to form a reflective type or a semi-transmissive type. 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.

[0056]

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 dipped in a dyeing bath (30 ° C.) containing iodine and kallium 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. for 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 having a thickness of 0.1 μm was formed on a TAC film having a thickness of 50 μm, and the surface of the alignment film was rubbed in a certain direction and then subjected to a rubbing treatment, and then a liquid crystal temperature range 90 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, on the cholesteric liquid crystal layer, a λ / 4 plate (front phase difference of 130 n
m) were stuck together to form 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 320 in the longitudinal direction.
A film having a size of mm × 250 mm and a film having a size of 320 mm × 250 mm were cut out from the brightness enhancement film. These films were laminated using an acrylic pressure-sensitive adhesive to produce an optical film laminate. In addition,
The axis angle was set so as to be 90 degrees with the absorption axis of the polarizing plate, and the brightness enhancement film was laminated so that the optical axis thereof was aligned with it. The obtained laminate was punched with a step having a product size (film (A): length 50 mm x width 40 mm, film (B): length 50 mm x width 35 mm, each protruding portion was 2.
5 mm) to obtain 6 laminated optical films.

Comparative Example 1 A film (A) having a length of 50 mm and a width of 40 mm was cut out from the polarizing plate with a retardation film produced in Example 1, and the brightness enhancement film produced in Example 1 was used to measure a length of 45 mm × width. A 35 mm film (B) was cut out separately. In the same manner as in Example 1, the film (B) was
The film (A) was laminated using an acrylic pressure-sensitive adhesive so that the protrusions on the four sides were 2.5 mm each, to prepare an optical film laminate (see FIG. 7). 20 test pieces were prepared.

With respect to the laminated optical films obtained in Examples and Comparative Examples, the respective sizes were measured with a digital caliper, and the width average of the protruding portions and the dispersity (σ) were obtained. The results are shown in Table 1. In addition, visual defects were visually confirmed and evaluated, but no abnormality was found.

[0063]

Table 1 Width average (mm) σ Judgment Example 1 2.52 0.13 ○ Comparative Example 1 2.58 0.47 ×

As is clear from Table 1, the laminated optical film 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, after the optical film (A) and the optical film (B) having different functions are laminated to form an optical film laminate, Since the laminated optical film is cut out by cutting this laminated body, the optical film having a predetermined shape can be processed at the same time as processing into a product size without using a step that has been conventionally performed, that is, a step of adhering an optical film cut into a size. Since a laminated body can be formed, the productivity is excellent. 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, since the cut optical film laminate has the protruding portion, by providing an adhesive layer on the portion (for example, sticking with a double-sided tape), It can be bonded to the liquid crystal cell with high accuracy, light leakage of the liquid crystal display device can be suppressed, and peeling in the module rework step can be prevented. Furthermore, by using the optical film laminate 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 of a polarizing plate used as an optical film (A).

FIG. 2 is a cross-sectional view showing the structure of a polarizing plate with a retardation film used as an optical film (A).

FIG. 3 is a plan view of a laminated optical film.

FIG. 4 is a cross-sectional view of a laminated optical film.

FIG. 5 is a conceptual diagram showing a structure in which a laminate of an optical film (A) and an optical film (B) is cut into a product size.

FIG. 6 is a view showing the structure of a punching blade die.

FIG. 7 is a plan view showing a configuration of a laminated optical film of a comparative example.

[Explanation of symbols]

1 Release film 2a adhesive 3a, 3b protective film 4 Polarizer 5 Polarizer 6a, 6b adhesive 7 Phase difference film 8a, 8b adhesive 9 λ / 4 plate 10 Cholesteric liquid crystal layer 11 Optical film (A) 12 Optical film (B) 13 Adhesive 14 Optical film laminate 15 punching blade type 16a Cutting blade (long blade) 16b Cutting blade (short blade)

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Claims (6)

[Claims] 1. A method for producing a laminated optical film comprising a laminate of a plurality of optical films having different areas, wherein the optical film (A) is provided on at least one side thereof.
A method for producing a laminated optical film, which comprises laminating an optical film (B) having a function different from that of (A) to form a laminated body, and then cutting the laminated body with a punching die having a step. 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 obtained by laminating at least one retardation film or a viewing angle compensation film 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.