KR20060086382A - Production method for polarization plate, polarization plate and image display unit using it - Google Patents

Abstract

A production method for a polarization plate having an excellent productivity without posing such problems as peeling-off, curling, cracking and blocking, a polarization plate obtained by such a production method, and an image display unit using such a polarization plate. The production metod for a polarization plate includes the steps of pasting a first transparent protection film having a moisture permeability of up to 200g/m2/24h to one surface of a polarizer to form a laminate, and then, without taking up the laminate, pasting a second transparent protection film having a moisture permeability higher than that of the first transparent protection film to the other surface of the polarizer.

Description

Manufacturing method of polarizing plate, polarizing plate, and image display apparatus using same {PRODUCTION METHOD FOR POLARIZATION PLATE, POLARIZATION PLATE AND IMAGE DISPLAY UNIT USING IT}

This invention relates to the manufacturing method of a polarizing plate, a polarizing plate, and the image display apparatus using the same. More specifically, the present invention is free from problems such as peeling, curling, cracking and blocking, and a polarizing plate having excellent polarization characteristics and durability obtained by a method for producing a polarizing plate having excellent productivity, such a manufacturing method, and its It relates to an image display device using the same polarizing plate.

The polarizing plate used for an image display apparatus (especially a liquid crystal display device) is a manufacturing method including the process of forming a polarizer, and the process of adhering the protective layer which consists of said polarizer and transparent protective films, such as a triacetyl cellulose (TAC) film. It is manufactured by. The step of forming a polarizer includes, for example, a dyeing step of dyeing a polyvinyl alcohol (PVA) film with iodine or dichroic dye having dichroism, a crosslinking step of crosslinking with boric acid or borax, and uniaxial stretching. An extending process and the drying process of drying a stretched film are included. In addition, each process of dyeing, bridge | crosslinking, and extending | stretching does not necessarily need to be performed separately, You may carry out several processes simultaneously and the order of each process is not specifically prescribed | regulated. In general, a polarizing plate manufactured has a TAC film bonded to both sides of a polarizer using an adhesive, so even if a total of three polarizers and three protective films are bonded at the same time, problems with the appearance and curl are caused. It can manufacture without making it.

However, since TAC film is inadequate in heat-and-moisture resistance, when the polarizing plate using a TAC film as a protective film is used under high temperature or high humidity, there exists a fault that the performance of polarizing plates, such as polarization degree and a hue, falls.

In order to solve such a problem, the method of using the transparent film which consists of resin with low water vapor transmission rate (for example, cyclic olefin resin) as a protective film of at least one surface of a polarizer is proposed. When using a protective film with such a low water vapor transmission rate, in order to facilitate drying of the adhesive agent used for adhesion | attachment of a polarizer and a protective film, the protective film with low moisture vapor transmission rate is made to adhere to one surface of a polarizer, and the other surface The protective film which has comparatively high moisture permeability is adhere | attached on it, and a polarizing plate is manufactured.

However, when the physical properties and thickness of the protective film to be adhered to both sides are different, when three sheets (that is, a polarizer, a protective film having a low moisture permeability and a protective film having a relatively high moisture permeability) are bonded at the same time, peeling or curling occurs at the time of bonding. Many times. As a result, not only the problem regarding external appearance and the problem of a work efficiency fall, but also the problem that the polarization performance of the polarizing plate obtained falls. In order to avoid such a problem, the method of thinning the thickness of a protective film is employ | adopted conventionally (for example, refer patent document 1).

Or the method of sticking and winding up a 1st protective film to one side of a polarizer, and sticking a 2nd protective film to the surface of the polarizer in which the 1st protective film is not adhered after that is proposed (example See, for example, Patent Document 2). According to this method, there exists a possibility that the blocking and the crack of the film wound up in the middle of a polarizing plate manufacturing process may arise, and productivity falls.

[Patent Document 1] Japanese Unexamined Patent Publication No. 2001-235625

[Patent Document 2] Japanese Unexamined Patent Publication No. 2002-196132

Disclosure of the Invention

Problems to be Solved by the Invention

This invention is made | formed in order to solve the said conventional subject, Comprising: It aims at providing the manufacturing method of the polarizing plate which does not have a problem of peeling, curl, crack, blocking, etc., and has excellent productivity. Another object of the present invention is to provide a polarizing plate having excellent polarization characteristics and durability obtained by such a production method. Another object of the present invention is to provide an optical film obtained by laminating at least one optical layer on such a polarizing plate, and an image display device using the polarizing plate and / or the optical film.

Means to solve the problem

The manufacturing method of the polarizing plate of this invention adhere | attaches the 1st transparent protective film which has a water vapor transmission rate of 200 g / m <2> / 24h or less to one surface of a polarizer, and forms a laminated body, and does not wind up the laminated body, It includes the process of adhering the 2nd transparent protective film which has a moisture permeability higher than a 1 transparent protective film to the other surface of this polarizer.

In preferable embodiment, the said manufacturing method adheres the said polarizer and said 1st transparent protective film in the state which provided the tension | tensile_strength to this polarizer and this 1st transparent protective film. In another preferable embodiment, the said manufacturing method adheres the said laminated body and said 2nd transparent protective film in the state which provided the tension | tensile_strength to this laminated body and this 2nd transparent protective film.

In a preferred embodiment, the curl amount of the laminate is 5 mm or less. In another preferable embodiment, the curl amount of the polarizing plate obtained is 5 mm or less.

In a preferred embodiment, the first transparent protective film is made of amorphous polyolefin resin.

In a preferred embodiment, the second transparent protective film is made of triacetyl cellulose.

In preferable embodiment, the said manufacturing method further includes the process of carrying out the drying process of the said laminated body before adhering said 2nd transparent protective film.

According to another aspect of the present invention, a polarizing plate is provided. This polarizing plate is obtained by said manufacturing method.

According to another aspect of the present invention, an optical element is provided. This optical element is obtained by laminating at least one optical layer on the polarizing plate.

According to still another aspect of the present invention, an image display device is provided. This image display apparatus has the said polarizing plate and / or the said optical element. As such an image display apparatus, a liquid crystal display apparatus, an electro luminescence (EL) display apparatus, a plasma display (PD), and a field emission display (FED: field emission display) are mentioned.

Effects of the Invention

According to the present invention, after a transparent protective film having a relatively low moisture permeability is adhered to a polarizer to form a laminate, the laminate is bonded to a transparent protective film having a relatively high moisture permeability without winding the laminate. By producing, peeling and curl at the time of adhesion are prevented. As a result, a polarizing plate having excellent durability and polarization characteristics is obtained with excellent productivity. In addition, according to the present invention, problems such as cracking and blocking due to the temporary winding of the laminate do not occur. That is, according to this invention, the problem which arises by adhering the transparent protective film which has a different characteristic (for example, elasticity modulus) or thickness to both sides of a polarizer can be solved, without making thickness of the said transparent protective film thin. have. This is considered to be one of the factors which enabled the drying which can remove water etc. suitably in the drying process after bonding a protective film. For example, when moisture and the like cannot be properly removed from the polarizing plate, discoloration phenomenon such as redness, light leakage phenomenon, or a phenomenon in which the transmittance is increased and the polarization degree is lowered, but according to the present invention, such a phenomenon It was actually confirmed that it did not appear.

1 is a schematic view illustrating a method of manufacturing a polarizing plate according to a preferred embodiment of the present invention.

2 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention.

3 is a schematic cross-sectional view illustrating the alignment state of liquid crystal molecules in the liquid crystal layer when the liquid crystal display device of the present invention employs a liquid crystal cell in VA mode.

4 is a schematic cross-sectional view of an organic EL display device according to an embodiment of the present invention.

Explanation of the sign

10 liquid crystal cell

11,11 'substrate

12 liquid crystal layer

20,20 'phase difference plate

30,30 'polarizer

40 light guide plate

50 light source

60 reflector

100 liquid crystal display

600 organic EL display

610 transparent substrate

620 transparent electrode

630 organic light emitting layer

631 Hole Injection Layer

632 light emitting layer

633 electron injection layer

640 counter electrode

650 pixels

To practice the invention  Best form for

A. Polarizer

The polarizing plate by preferable embodiment of this invention has a polarizer, the 1st transparent protective film formed in one surface of this polarizer, and the 2nd transparent protective film formed in the other one surface of this polarizer.

As the polarizer, any suitable polarizer may be employed depending on the purpose. For example, a biaxial substance such as iodine or a dichroic dye is adsorbed onto hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and ethylene-vinyl acetate copolymer-based partially saponified films. And polyene oriented films such as stretched, dehydrated polyvinyl alcohol and dehydrochloric acid polyvinyl chloride. Among these, the polarizer which uniaxially stretched by adsorb | sucking dichroic substances, such as iodine, on a polyvinyl alcohol-type film is especially preferable because a polarization dichroic ratio is high. The polarizer may contain boric acid, zinc sulfate, zinc chloride, etc. as needed. Although the thickness in particular of a polarizer is not restrict | limited, Usually, it is about 5-80 micrometers.

The water vapor transmission rate of the said 1st transparent protective film is 200g / m <2> / 24h or less, Preferably it is 0-100g / m <2> / 24h. Water vapor transmission rate is a measured value in 40 degreeC and 92% RH based on JISZ0202. An amorphous polyolefin resin is mentioned as a typical material which forms the film which has such a water vapor transmission rate. As amorphous polyolefin resin, resin which has a polymerization unit of cyclic olefins, such as a norbornene and a polycyclic norbornene-type monomer, resin which consists of a copolymer of a cyclic olefin and a linear olefin, etc. are mentioned, for example.

The said 1st transparent protective film may be a film formed from the resin composition containing the thermoplastic resin which has a substituted and / or unsubstituted imide group in a side chain, and the thermoplastic resin which has a substituted and / or unsubstituted phenyl group in a side chain. The resin composition may have an olefin component. As a specific example, the polymer film of the resin composition containing the glutalimide copolymer which consists of N-methyl glutalimide and methyl methacrylate, and an acrylonitrile styrene copolymer, isobutylene, and N-methyl maleimide The polymer film of the resin composition containing the alternating copolymer which consists of an acrylonitrile styrene copolymer, etc. are mentioned.

On the adhesive surface with the polarizer of the said 1st transparent protective film, the process which improves adhesive force can be performed as needed. Representative examples of such treatments include dry treatments and easy adhesion treatments. Specific examples of the dry treatment include corona treatment, gas corona treatment, plasma treatment, low pressure UV treatment, and the like. As a specific example of an easily bonding process, coating of an easily bonding material is mentioned. As an easily bonding material, a cellulose resin, a urethane resin, a silane coupling agent, a silicone primer, PVA, nylon, a styrene resin, etc. are mentioned. Dry processing and an easily bonding process can also be used together. Alternatively, the adhesive force can be improved by performing a saponification treatment with an aqueous sodium hydroxide solution. A saponification process can also be used together with an easily bonding process.

In one embodiment, the said 1st transparent protective film can also function as a retardation film. What is necessary is just to extend | stretch a said 1st transparent protective film, when using a 1st transparent protective film as retardation film. Stretching conditions (for example, draw ratio, draw direction, and stretch temperature) can be appropriately set according to the purpose or desired phase difference.

As the second transparent protective film, any suitable transparent film can be employed as long as it has a higher moisture permeability than the first transparent protective film. You may select 2 types of films which have a different moisture permeability from what was listed as said 1st transparent protective film, and let the thing with a lower water vapor transmission rate as a 1st transparent protection film, and use a thing with a higher water vapor transmission rate as a 2nd transparent protection film. . Alternatively, transparent films other than those listed as the first transparent protective film may be used as the second transparent protective film.

As a transparent film other than what is listed as said 1st transparent protective film, a cellulose resin film is mentioned, for example. More specifically, cellulose acetate type resin films, such as a triacetyl cellulose film and a diacetyl cellulose film, are mentioned. Triacetyl cellulose is preferred, and saponified triacetyl cellulose film is more preferred.

The water vapor transmission rate of the said 2nd transparent protective film becomes like this. Preferably it is 200-1000 g / m <2> / 24h, More preferably, it is 300-900 / m <2> / 24h.

The thickness of the said 1st transparent protective film and said 2nd transparent protective film is not specifically limited. The thickness of the said 1st transparent protective film and the said 2nd transparent protective film is independent independently, and is typically 500 micrometers or less, Preferably it is 1-300 micrometers, More preferably, it is 5-200 micrometers, Most preferably Preferably it is 5-100 micrometers. As described above, even if the thickness of the transparent protective film is increased to a maximum of about 500 µm, it is one of the great features of the present invention to prevent curling and peeling. By being able to use a thick transparent protective film, it becomes possible to manufacture the polarizing plate which was very excellent in durability (for example, heat resistance and moisture resistance). On the other hand, even when it is used for the use which requires thickness reduction of an image display apparatus, since the transparent protective film used for this invention can be made thin to about 1 micrometer, it is fully compatible.

As for the said 1st transparent protective film and the said 2nd transparent protective film, it is preferable that there is no coloring as much as possible. Therefore, retardation Rth of the thickness direction of a 1st transparent protective film and a 2nd transparent protective film is respectively independent, Preferably it is -90 nm-+75 nm, More preferably, it is -80-+60 nm, Most preferably Is -70nm to + 45nm. By using the film which has Rth of such a range, coloring (optical coloring) of a polarizing plate resulting from a transparent protective film can be substantially eliminated. In addition, the phase difference Rth in the thickness direction is represented by Rth = [(nx + ny) / 2-nz] · d. Here, nx and ny are the principal refractive index in a film plane, nz is the refractive index of a film thickness direction, and d is a film thickness.

B. Manufacturing Method of Polarizing Plate

Hereinafter, a preferable example of the manufacturing method of the polarizing plate of this invention is demonstrated. First, the manufacturing method of a polarizer is demonstrated. Here, the manufacturing method of the polarizer which uniaxially stretched by adsorb | sucking dichroic substances, such as iodine, on a polyvinyl alcohol-type film is demonstrated. Such a polarizer is manufactured by the manufacturing method including a swelling process, a dyeing process, a crosslinking process, and an extending process, for example. In the swelling step, the polyvinyl alcohol-based film is immersed in water to swell the film. By immersing in water and washing with water, the dirt and blocking prevention agent of the polyvinyl alcohol-type film surface can be wash | cleaned. Further, by swelling the polyvinyl alcohol-based film, there is an effect of preventing nonuniformity such as staining of the dyeing. In the dyeing step, the polyvinyl alcohol-based film is dyed in a bath containing a dye such as a dichroic substance such as iodine or a dichroic dye. In the crosslinking step, the polyvinyl alcohol-based film is crosslinked in a bath containing a crosslinking agent such as boric acid or borax. In the stretching step, the polyvinyl alcohol-based film is stretched 3 to 7 times the original length. These process orders are not specifically limited, You may perform several processes simultaneously. For example, extending | stretching may be performed after dyeing with iodine, you may extend | stretching while dyeing, and you may dye with iodine after extending | stretching. It can extend | stretch in aqueous solution, such as a boric acid and potassium iodide, or in a water bath.

Next, the polarizer and the transparent protective film are bonded together. In the manufacturing method of this invention, the said 1st transparent protective film and the said 2nd transparent protective film are adhere | attached one side of a polarizer separately. Since the first transparent protective film and the second transparent protective film each have different characteristics (for example, elastic modulus and moisture permeability), curling or peeling occurs when the polarizer and two protective films are bonded at the same time. Because there are cases. In addition, in the manufacturing method of this invention, as shown in FIG. 1, after bonding the 1st transparent protective film 32 to one surface of the polarizer 31, and forming the laminated body 35, The 2nd transparent protective film 33 is stuck to the other surface of the polarizer 31, without winding up the said laminated body 35, and the polarizing plate 30 is obtained. Thus, by bonding the 2nd transparent protective film 33 without winding up the laminated body 35 of the polarizer 31 and the 1st transparent protective film 32, blocking and a crack are prevented and the obtained polarizing plate The deterioration of the optical properties of can be prevented. Moreover, since the installation space of a manufacturing apparatus can be made very small and there is no loss of time by a winding process, production efficiency can be improved significantly and manufacturing cost can be reduced significantly.

The bonding process of the said laminated body and said 2nd transparent protective film may be performed continuously in the adhering process of a polarizer and a 1st transparent protective film, as shown in FIG. For example, you may perform after drying process and the process which improves adhesive force. In the case of adhering the second protective film continuously, a polarizing plate is obtained with very excellent productivity. When performing another operation | movement to the laminated body 35, the polarizing plate which has the further outstanding characteristic according to the objective is obtained. In one embodiment, the bonding process of the said laminated body and said 2nd transparent protective film is performed after performing a drying process to the said laminated body. By carrying out the drying process, the excess moisture can be removed very well, so that discoloration phenomenon such as redness, light leakage phenomenon, or a phenomenon in which the transmittance is increased and the polarization degree is lowered can be significantly prevented. The conditions (for example, drying temperature, drying time, drying method) of a drying process can be suitably set according to the objective. For example, a drying temperature is 40-90 degreeC, and a drying time is 1 to 10 minutes.

As for the bonding order of a transparent protective film, it is preferable to adhere | attach a 1st transparent protective film (film with a relatively small moisture permeability) to a polarizer, and then adhere | attach a 2nd transparent protective film (film with a relatively large moisture permeability). By adhering in this order, when the drying process is performed at an appropriate time point as described above, the excess moisture can be removed very well. As a result, a polarizing plate having very excellent polarization characteristics and display characteristics is obtained.

Preferably, adhesion | attachment of the said polarizer and a 1st transparent protective film, and adhesion | attachment of the said laminated body and a 2nd transparent protective film are performed, performing the process which the state after adhesion becomes flat. In the present invention, whether or not the state after adhesion is flat is determined based on the curl amount. In the present specification, the term "curls" refers to a sample obtained by punching a laminate or a polarizing plate obtained by adhesion into a size of 100 mm x 100 mm in a 45 ° direction with respect to the absorption axis of the polarizer, and placing the sample on a flat surface. It refers to the space distance P lifted from the flat surface. The smaller the curl amount of the laminate or the polarizing plate, the more preferable the state after adhesion is flat. Specifically, the amount of curl is preferably 5 mm or less, and more preferably 3 mm or less.

 As a typical example of the treatment in which the state after the adhesion is flattened, a method of bonding the polarizer and the first transparent protective film in a state where tension is applied to the polarizer and the first transparent protective film is mentioned. This method is similarly applied to adhesion of a laminated body and a 2nd transparent protective film. As a method of providing a tension, the method of using the peripheral speed difference of the guide roll which conveys a polarizer and a transparent protective film is mentioned, for example. More specifically, when bonding a polarizer and a 1st transparent protective film, for example, what is necessary is just to make the rotation speed of the roll 36 of the winding side of FIG. 1 faster than the rotation speed of the roll 37 of a sending side. The rotation speed of a roll can be suitably set according to the objective or desired tension.

Bonding of the said polarizer and said 1st or 2nd transparent protective film is performed using an adhesive agent typically. As the adhesive, any suitable adhesive having good adhesion to the polarizer and the transparent protective film may be employed. For example, when a polarizer is a polyvinyl alcohol (PVA) type film, the adhesive agent containing PVA type resin is preferable. It is because it is especially excellent in adhesiveness with a polarizer. Arbitrary suitable PVA system resin can be employ | adopted as PVA system resin. Representative examples include unsubstituted PVA and PVA having a highly reactive functional group. PVA having a highly reactive functional group is particularly preferred. It is because durability of the polarizing plate obtained can further remarkably improve. As a specific example of PVA which has a highly reactive functional group, the acetacetyl group modified | denatured PVA resin is mentioned. The degree of polymerization of the binder resin (for example, PVA resin) of the adhesive is preferably 100 to 3000. By having the polymerization degree of this range, adhesiveness with a polarizer and a transparent protective film can become especially favorable. Although the thickness of an adhesive bond layer can be set suitably according to the objective and the use of the image display apparatus in which a polarizing plate is used, Preferably it is 30-300 nm, More preferably, it is 50-150 nm. In addition, an adhesive bond layer is formed by apply | coating and drying adhesive aqueous solution.

Preferably, the adhesive may further contain a crosslinking agent. The crosslinking agent is preferably a water-soluble crosslinking agent. Specific examples of the water-soluble crosslinking agent include boric acid, borax, glutaraldehyde, melamine, oxalic acid, and the like. If desired, the adhesive may further contain any suitable additives (eg antioxidants, ultraviolet absorbers) and / or catalysts (eg acids).

C. Optical element

According to another aspect of the present invention, an optical element is provided. This optical element consists of an optical layer laminated | stacked on the said polarizing plate. As the optical layer, any suitable optical layer may be employed depending on the purpose. In more detail, various optical films which can improve the display precision and / or visibility of an image display apparatus are mentioned as an optical layer. Specific examples of such an optical layer include an alignment liquid crystal layer, a reflecting plate, a semi-transmissive plate, a retardation plate (for example, a λ / 2 plate, a λ / 4 plate), a vision compensation film, a brightness enhancement film, and the like. Specific examples of the optical element combining the polarizing plate and the optical layer include a reflective polarizing plate (combination of a polarizing plate and a reflecting plate), a semi-transmissive polarizing plate (combining a polarizing plate and a transflective reflecting plate), and a polarizing plate with a retardation plate (combining a polarizing plate and a phase difference plate) ), Elliptical polarizer or circular polarizer (combination of polarizing plate and λ / 4 plate), wide viewing angle polarizing plate (combination of polarizing plate and visual compensation layer or visual compensation film), polarizing plate with brightness enhancement film (combination of polarizing plate and brightness enhancement film) ). In addition, in this specification, an "optical layer" includes the surface treatment part (surface treatment layer) performed on the surface which did not adhere the polarizer of the said transparent protective film. Specific examples of such surface treatment include hard coat treatment, antireflection treatment, anti-sticking treatment, diffusion or antiglare treatment.

One layer or two or more layers may be sufficient as an optical layer. When two or more optical layers are present, each layer may be the same and may combine said various optical layers suitably. Typically, by combining optical layers having different characteristics, an image display device having better display accuracy and / or visibility can be obtained. The stacking position (substantially, the stacking order) of the optical layer may be appropriately set according to the purpose. For example, before attaching a polarizer and a transparent protective film, an optical layer may adhere to a polarizer and may adhere to a transparent protective film. For example, after sticking a polarizer and a transparent protective film, you may adhere to the obtained laminated body or polarizing plate. For example, you may adhere | attach a polarizer, a transparent protective film, and an optical layer simultaneously. Further, the polarizer and the optical layer can be laminated so that their optical axes (for example, the absorption axis of the polarizer, the slow axis of the optical layer) define an appropriate angle according to the purpose. In addition, any appropriate pressure-sensitive adhesive may be used for lamination (adhesion) of the polarizing plate and the optical layer.

C-1. Surface treatment layer

The hard coat treatment is performed for the purpose of preventing damage to the surface of the polarizing plate. A hard coat process is performed by forming the cured film which has the outstanding hardness and slipperiness, for example. The cured coating is typically formed using an ultraviolet curable resin (for example, acrylic resin or silicone resin). The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate. The antireflection treatment is performed by forming any suitable antireflection film. The sticking prevention treatment is performed for the purpose of preventing adhesion to an adjacent layer.

The said antiglare process is performed in order to prevent external light from reflecting off the surface of a polarizing plate, and to impair visibility of the polarizing plate transmitted light. Antiglare treatment is typically performed by giving a fine uneven structure to the surface of a transparent protective film. Specific examples of the means for imparting the fine concavo-convex structure include roughening by sandblasting or embossing, concavity formation by transparent fine particles, and the like. Uneven | corrugated formation by transparent fine particles is performed by apply | coating and drying the composition containing transparent resin and transparent fine particles on the transparent protective film surface. Examples of the transparent fine particles used for forming the irregularities include organic fine particles made of inorganic fine particles which may be conductive such as silica, alumina, titania, zirconia, oxide, indium oxide, cadmium oxide, and antimony oxide, crosslinked or uncrosslinked polymer, and the like. Can be. The average particle diameter of the said transparent fine particle becomes like this. Preferably it is 0.5-50 micrometers. The amount of the transparent fine particles used is preferably about 2 to 70 parts by weight, more preferably 5 to 50 parts by weight based on 100 parts by weight of the transparent resin. The antiglare layer formed by the antiglare treatment may also serve as a diffusion layer that diffuses the polarizing plate transmitted light and enlarges the vision and the like (ie, has a visual magnification function).

The surface treatment layer as mentioned above may be formed in the transparent protective film itself by surface-treating on a transparent protective film, and may laminate | stack a separate independent film on the transparent protective film surface.

C-2. Reflective Polarizer

The reflective polarizing plate is formed by forming a reflecting plate (reflective layer) made of metal or the like on one surface of the polarizing plate. Between a polarizing plate and a reflecting film, a transparent protective layer etc. are formed as needed. A matt process etc. are performed to a transparent protective layer as needed. The reflective polarizing plate is preferably used for a reflective liquid crystal display device (a liquid crystal display device for reflecting and displaying incident light from the viewing side (display side)). By using the reflective polarizing plate, there is no need to incorporate a light source such as a backlight in the liquid crystal display device, and thus advantages such as thinning of the liquid crystal display device can be obtained.

Representative examples of the material constituting the reflective layer include a reflective metal such as aluminum. The reflective layer may be formed by adhering such a reflective metal foil to a transparent protective film or may be formed by vapor deposition. The reflective layer may have a fine uneven structure on the surface. Such a reflective layer is obtained by, for example, containing fine particles in a transparent protective film during forming a protective film, forming a fine uneven structure on the surface thereof, and forming a layer of a reflective metal thereon. That is, such a reflection layer is formed reflecting the fine concavo-convex structure of the transparent protective film surface. By forming a reflective layer having a fine concavo-convex structure, the incident light can be diffused by diffuse reflection to prevent directivity and glare, thereby suppressing light and light unevenness. In addition, since the fine particle-containing transparent protective film itself also has a function of diffusing when incident light and its reflected light pass therethrough, unevenness in contrast can be further suppressed. The reflective layer reflecting the surface fine concavo-convex structure of the transparent protective film is formed by, for example, a vapor deposition method such as vacuum deposition, ion plating, sputtering, or a plating method. Alternatively, instead of forming the reflective layer directly on the transparent protective film surface, a reflective plate formed by forming a reflective layer on a suitable base film may be used. In addition, since a reflective layer is normally comprised from a metal, it is preferable to use it in the state in which the reflective surface was coat | covered with a transparent protective film, a polarizing plate, etc. This is because the reduction of the reflectance due to oxidation is prevented, so that the initial reflectance can be maintained for a long time, and it is not necessary to form a protective layer separately.

C-3. Transflective Polarizer

The semi-transmissive polarizing plate is formed by forming a semi-transmissive reflecting plate (reflective layer) on one surface of the polarizing plate. The semi-transmissive reflective layer is typically a half mirror that reflects and transmits light. The transflective polarizing plate is applied to a transflective liquid crystal display device. In a transflective liquid crystal display device, a transflective polarizing plate is normally formed in the back side of a liquid crystal cell. The semi-transmissive liquid crystal display device displays an image by reflecting incident light from the viewing side (display side) when used in a relatively bright environment, and uses a built-in light source such as a backlight when used in a relatively dark environment. Display an image. Therefore, the use of the transflective polarizing plate saves the energy of using a light source such as a backlight in a bright environment, thereby realizing power saving, and also makes it easier to see the display because it uses light emitted from the light source even in a relatively dark environment. Advantage is obtained.

C-4. Polarizer with Retardation Plate

In the polarizing plate with a retardation plate, the retardation plate is laminated on the polarizing plate. As the retardation plate, a retardation plate having any suitable optical characteristics may be employed depending on the purpose. For example, when changing the polarization direction of linearly polarized light, the λ / 2 plate is used as the phase difference plate. For example, when changing linearly polarized light into elliptical polarization or circularly polarized light, or changing elliptical polarization or circularly polarized light into linearly polarized light, λ / 4 plate is used as a retardation plate (a polarizing plate with such retardation plate Polarizer or circular polarizer). The elliptical polarizing plate is effectively used for compensating (preventing) the coloration (blue or sulfur) generated by the birefringence of the liquid crystal layer of the super twisted nematic (STN) type liquid crystal display device to realize black and white display without coloration. . Moreover, the elliptical polarizing plate which controlled the refractive index three-dimensionally is especially preferable because the coloring degree which arises when the screen of a liquid crystal display device is seen from the inclination direction can be compensated (prevented). In one embodiment, the λ / 4 plate can form a reflective elliptical polarizing plate in combination with a reflective polarizing plate. The circular polarizing plate is effectively used, for example, when the image has a color tone of an image of a reflective liquid crystal display device in which color is displayed, and also has a function of antireflection. In addition to the λ / 2 plate and the λ / 4 plate, a retardation plate having a refractive index distribution for compensating coloring and visual characteristics due to birefringence of the liquid crystal layer of the liquid crystal display device, a retardation plate having a phase difference corresponding to various wavelengths, and the like are used. . The retardation plates may be used alone or in combination of two or more kinds having different characteristics.

As said retardation plate, the birefringent film formed by uniaxial or biaxial stretching treatment of a polymeric material, the orientation film of a liquid crystal polymer, the thing which supported the orientation layer of a liquid crystal polymer with a film, etc. are mentioned. An extending | stretching process can be performed by the roll extending | stretching method, the long-gap extending | stretching method, the tenter stretching method, the tubular stretching method, etc., for example. In the case of uniaxial stretching, the draw ratio is generally about 1.1 to 3 times. The thickness of the retardation plate is also not particularly limited, but is generally 10 to 200 m, preferably 20 to 100 m.

Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, and polyallylate. , Polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, polyphenylene sulfide, polyphenylene oxide, polyallyl sulfone, polyvinyl alcohol, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose polymer Or these binary or ternary various copolymers, graft copolymers, blends and the like. By performing an extending | stretching process etc. to the film formed from these polymer materials, birefringence (phase difference) is provided.

Examples of the liquid crystal polymer include a main chain type liquid crystal polymer in which a conjugated rigid atomic group (mesogen) capable of expressing liquid crystal is introduced into the polymer main chain, and a side chain type liquid crystal polymer in which mesogen is introduced into the side chain. Can be mentioned. More specifically, the main chain type liquid crystal polymer has a structure in which a mesogenic group is bonded through a spacer portion that provides flexibility. Specific examples of the main chain type liquid crystal polymer include nematic oriented polyester liquid crystal polymers, discotic polymers, cholesteric polymers, and the like. Specific examples of the side chain type liquid crystal polymer include a polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a para-substituted cyclic compound having a nematic orientation imparting property through a spacer portion composed of a conjugated atomic group as a side chain. The polymer etc. which have a mesogenic part which consists of units are mentioned. The alignment film of a liquid crystal polymer is formed by apply | coating the solution containing these liquid crystal polymers on the orientation-processed board | substrate, and heat-processing at the temperature which the said liquid crystal polymer expresses a liquid crystal phase, and is formed by immobilizing a liquid crystal phase. . As a specific example of the orientation-treated board | substrate, the thing which carried out the rubbing process of the surface of thin films, such as polyimide and polyvinyl alcohol formed on the glass plate, the thing which vapor-deposited silicon oxide etc. are mentioned.

The polarizing plate with the retardation plate may be formed by sequentially laminating the polarizing plate and the retardation plate in the manufacturing process of the liquid crystal display device, but it is intended to be actually used as a polarizing plate with an integrated retardation plate in which the polarizing plate and the retardation plate are laminated in advance. desirable. It is because manufacturing efficiency, such as a liquid crystal display device, can be improved because it is excellent in stability of quality and lamination workability.

C-5. Wide viewing angle polarizer

The visual compensation film used for a wide viewing angle polarizing plate is a film for enlarging a viewing angle so that an image may be seen clearly, even when the screen of an image display apparatus (typically, a liquid crystal display device) is seen from the diagonal direction. As such a visual compensation film, what supported the alignment layers, such as a liquid crystal polymer, on orientation films, such as a retardation plate and a liquid crystal polymer, or a transparent base material, etc. are mentioned, for example. The retardation plate used as the visual compensation film is a polymer film having a birefringence stretched in two axes in the plane direction, a polymer having a birefringence in which the refractive index in the thickness direction is stretched in one plane in the plane direction and also stretched in the thickness direction. A bidirectional stretched film, such as a film or a diagonal oriented film, is mentioned. Examples of the diagonally oriented film include a film obtained by adhering a heat-shrink film to a polymer film, stretching and / or shrinking the polymer film under the action of shrinkage force by heating, and tilting the liquid crystal polymer. Can be. As a polymer material which comprises the retardation plate used as a visual compensation film, it is suitable for arbitrary coloring which prevents coloring by the change of the viewing angle resulting from the birefringence of a liquid crystal cell (liquid crystal layer), and enlarges the viewing angle which obtains favorable visibility. Polymeric materials can be used. Specifically, the same polymer material as that described in the above ordinary retardation plate is used. Moreover, as a specific example of the visual compensation film which supported alignment layers, such as a liquid crystal polymer, on the transparent base material, the visual compensation film which supported the diagonal alignment layer of the discotic liquid crystal polymer on the triacetyl cellulose film base material is mentioned. Such a visual compensation film can greatly enlarge the viewing angle at which favorable visibility is obtained.

C-6. Polarizer with Brightness Enhancement Film

The polarizing plate with a brightness improving film is normally formed and used on the back surface of a liquid crystal cell. When natural light enters, a brightness improving film reflects the linear polarization which has a predetermined polarization direction, or circular polarization which has a predetermined rotation direction, and the other light transmits. Therefore, when the light emitted from light sources, such as a backlight, enters the polarizing plate with a brightness improving film, only the polarization of a predetermined polarization state will transmit from the said incident light, and other polarizations will reflect. This reflected light is inverted through a reflective layer formed on the rear of the brightness enhancing film or the like and re-incident to the brightness improving film, and the light transmitted through the brightness enhancing film is transmitted by transmitting part or all of the reflected light as polarized light in a predetermined polarization state. It can increase the light which can be used for liquid crystal image display etc. by increasing the polarization hardly absorbed by a polarizer. As a result, the luminance of the liquid crystal display device can be improved. In other words, when the brightness enhancement film is not used, when the light emitted from the light source is incident on the rear surface of the liquid crystal cell through the polarizer, the light having a polarization direction that does not coincide with the polarization axis of the polarizer is substantially absorbed by the polarizer. Does not transmit polarizer. As a result, since about 50% of the light emitted from the light source is absorbed by the polarizer, the amount of light that can be used for liquid crystal image display or the like decreases, and the image becomes dark. The brightness enhancement film repeatedly reflects light having a polarization direction absorbed by the polarizer without incident to the polarizer, and is reflected once in the brightness enhancement film, and is inverted through a reflective layer or the like formed at the rear thereof, and reenters the brightness enhancement film. The polarization direction of the light reflected and inverted between the brightness enhancing film and the reflective layer thereby transmits only the polarized light that is the polarization direction through which the polarizer can pass, and supplies the polarizer to the light emitted from the light source, thereby efficiently providing an image of the liquid crystal display device. It can be used for display and can brighten the screen.

A diffusion plate may be formed between the brightness enhancing film and the reflective layer. As described above, the light in the polarization state reflected by the brightness enhancing film is directed toward the reflective layer. By forming a diffuser plate in the path of the light, the light passing through the path is uniformly diffused, the polarization state is eliminated, and the light is returned to the non-polarized state (that is, the original natural light state). The light of this non-polarization state (natural light state) is inverted through a reflection layer or the like, and the light is passed through the diffuser plate again and reincident to the brightness enhancing film. As a result, while maintaining the brightness of the display screen, the brightness unevenness can be reduced to provide a bright uniform screen. This is thought to be appropriately increased the number of times the first incident light reflects and inverts by forming the diffuser plate, and both brightness and uniformity are improved by the synergistic effect with the diffuser function of the diffuser plate.

Specific examples of the brightness enhancement film include a property of transmitting only linearly polarized light having a predetermined polarization direction to reflect different light (for example, multilayer multilayer thin films of dielectrics, multilayer laminates of thin film films having different refractive index anisotropy). , Which exhibits a characteristic of reflecting any one circularly polarized light before left turn or bypass and transmitting the other (for example, supporting an oriented film of a cholesteric liquid crystal polymer and a cholesteric alignment liquid crystal layer on a film substrate) Can be mentioned.

According to the luminance improvement film of the type which transmits only linearly polarized light which has a predetermined polarization direction as mentioned above, it is a result of absorption by a polarizing plate by making the polarization direction of the transmitted light match the polarization axis of a polarizing plate, and making incident light into a polarizing plate as it is. The loss to be suppressed can be suppressed and the polarizing plate can be efficiently transmitted. On the other hand, according to the brightness improving film of the type which transmits circularly polarized light which has a predetermined rotation direction like a cholesteric liquid crystal layer, it is preferable to make it enter into a polarizing plate after converting the circularly polarized light transmitted into linearly polarized light. It is for suppressing the loss resulting from absorption by a polarizing plate. A retardation plate (typically a λ / 4 plate) is used for conversion from circularly polarized light to linearly polarized light. The retardation plate may be a single layer of λ / 4 plate or a laminate including a λ / 4 plate. For example, a retardation plate that functions as a λ / 4 plate in a wide wavelength range (for example, the entire visible light region), and exhibits different retardation characteristics from a retardation layer that functions as a λ / 4 plate for monochromatic light having a wavelength of 550 nm. A retardation plate in which a retardation layer (for example, a retardation layer functioning as a λ / 2 plate) is laminated is preferably used. Moreover, also about a cholesteric liquid crystal layer, the brightness improvement film which reflects circularly polarized light in a very wide wavelength range (for example, whole visible light reverse region) is obtained by using combining two or more layers which have a different reflection wavelength. . By using such a brightness improving film, the transmission circular polarization applicable to a wide wavelength range can be obtained.

C-7. Etc

As above-mentioned, the optical layer used for the optical element of this invention is used combining suitably according to the objective. For example, the optical element of this invention is a reflection ellipse polarizing plate which combined the reflection type polarizing plate (item C-2) and retardation plate, or the half which combined the semi-transmissive polarizing plate (item C-3) and retardation plate. A transmissive elliptical polarizing plate may be used.

When manufacturing an image display apparatus, the optical element of this invention may be formed by laminating | stacking a polarizing plate and an optical layer one by one, and may be used as an integrated optical element which laminated | stacked the polarizing plate and the optical layer previously. Integral type is preferred. It is because it is excellent in stability of quality, assembly | work, etc., and can improve the manufacturing efficiency of an image display apparatus.

In the polarizing plate and optical element of this invention, the adhesive layer for adhere | attaching with the other member (for example, liquid crystal cell) of an image display apparatus may be formed practically. It is preferable that an adhesive layer is low in moisture absorption and excellent in heat resistance. This is because foaming and peeling phenomenon due to moisture absorption are prevented, and deterioration of optical properties due to thermal expansion difference or the like and warping of the liquid crystal cell are prevented, so that an image display device having high quality and durability is obtained. The pressure-sensitive adhesive layer may be formed from, for example, an acrylic pressure-sensitive adhesive. As needed, an adhesive layer contains microparticles | fine-particles and may have light diffusivity. The pressure-sensitive adhesive layer may be formed at any suitable place according to the purpose. For example, in the polarizing plate which has a polarizer and a protective film on both sides, an adhesive layer may be provided on the surface of either protective film, and an adhesive layer may be formed on both protective film surfaces.

When forming an adhesive layer by exposing to the surface of a polarizing plate or an optical element, it is preferable to carry out an adhesive cover with a separator for the purpose of preventing contamination of the adhesive layer until it is actually used. A separator is formed by providing a peeling coat as needed to the appropriate thin film formed from the material used for said transparent protective film. The release coat typically consists of a release agent layer such as silicon, long chain alkyl, fluorine or molybdenum sulfide.

In addition, you may provide the ultraviolet absorbing ability to each layer (specifically, a polarizer, a transparent protective film, an optical layer, an adhesive layer) which comprises the polarizing plate and / or optical element of this invention as needed. The ultraviolet absorbing ability is imparted by introducing a ultraviolet absorbent into the layer, for example. As a ultraviolet absorber, a salicylic acid ester type compound, a benzophenone type compound, a benzotriazole type compound, a cyanoacrylate type compound, a nickel complex salt type compound, etc. are mentioned, for example.

D. Image Display

D-1. Liquid crystal display

2 is a schematic cross-sectional view of a liquid crystal display device according to a preferred embodiment of the present invention. Although the transmissive liquid crystal display device is demonstrated in the example of illustration, it goes without saying that this invention is applied also to a reflection type liquid crystal display device.

The liquid crystal display device 100 includes the liquid crystal cell 10, the retardation plates 20 and 20 ′ interposed with the liquid crystal cell 10, and the polarizing plates 30 and 30 arranged outside the retardation plates 20 and 20 ′. '), Light guide plate 40, light source 50, and reflector 60. The polarizing plates 30 and 30 'are typically arranged so that the polarization axes of the polarizers are perpendicular to each other. The polarizing plates 30 and 30 'are the polarizing plates of the said invention. When the polarizing plates 30 and 30 'are the optical elements of the present invention (that is, the combination of the polarizing plate and various optical layers), the retardation plates 20 and 20' can be omitted. The liquid crystal cell 10 has a pair of substrate (glass substrate or plastic substrate) 11, 11 'and the liquid crystal layer 12 as a display medium arrange | positioned between this substrate. On one board | substrate 11, the switching element (typically TFT) which controls the electro-optical characteristic of a liquid crystal, the scanning line which provides a gate signal to this switching element, and the signal line which provides a source signal are formed (both illustration Not). The other board | substrate 11 'is provided with the color layer which comprises a color filter, and the light shielding layer (black matrix layer) (both not shown). The gap (cell gap) between the substrates 11 and 11 'is controlled by the spacer 13.

As the display mode of the liquid crystal cell 10, any suitable display mode can be adopted as long as the effect of the present invention is obtained. Typically, VA (Vertical Alignment) mode, OCB (Optically Compensated Birefringence) mode, Twisted Nematic (TN) mode, Super Twisted Nematic (STN) mode, Horizontal Orientation (ECB) mode, Inflation Switching (IPS) mode , Ferroelectric liquid crystal (SSFLC) mode, anti-ferroelectric liquid crystal (AFLC) mode, and the like. Hereinafter, the VA mode will be described as an example.

3 is a schematic cross-sectional view illustrating the alignment state of liquid crystal molecules in VA mode. As shown in Fig. 3A, when no voltage is applied, the liquid crystal molecules are vertically aligned with the substrate 11, 11 'plane. Such vertical alignment can be realized by disposing a nematic liquid crystal having negative dielectric anisotropy between the substrates on which the vertical alignment film (not shown) is formed. When light is incident on the surface of one substrate 11 in such a state, light of linearly polarized light passing through the polarizing plate 30 and entering the liquid crystal layer 12 proceeds along the long axis direction of the liquid crystal molecules that are vertically aligned. do. Since birefringence does not occur in the long axis direction of the liquid crystal molecules, incident light proceeds without changing the polarization direction and is absorbed by the polarizing plate 30 'having an absorption axis orthogonal to the polarizing plate 30. As a result, the display of the dark state is obtained when no voltage is applied (normally black mode). As shown in Fig. 3B, when a voltage is applied between the electrodes, the long axis of the liquid crystal molecules is aligned in parallel with the substrate surface. The liquid crystal molecules show birefringence with respect to the linearly polarized light incident on the liquid crystal layer 12 in this state, and the polarization state of the incident light changes with the inclination of the liquid crystal molecules. The light passing through the liquid crystal layer at the time of application of the predetermined maximum voltage becomes linearly polarized light in which the polarization direction is rotated by 90 °, for example, so that the display in the bright state is obtained through the polarizing plate 30 '. When the voltage is not applied again, the display of the dark state can be returned by the orientation regulating force. In addition, gray scale display is possible by changing the applied voltage to control the inclination of the liquid crystal molecules to change the intensity of transmitted light from the polarizing plate 30 '.

D-2. Self-luminous display

The present invention can be applied not only to a liquid crystal display device but also to a self-luminous display device such as an electroluminescence (EL) display, a plasma display (PD), and a field emission display (FED). Here, an organic electroluminescent (EL) display apparatus is demonstrated as an example.

4 is a schematic cross-sectional view of an organic electroluminescence (EL) display device according to a preferred embodiment of the present invention. The organic EL display device 600 is disposed so as to cover the transparent substrate 610, the transparent electrode 620, the organic light emitting layer 630, and the counter electrode 640 sequentially formed on the transparent substrate 610. An inorganic protective film 660 and a resin protective film 670 are provided. The pixel 650 is the transparent electrode 620, the organic light emitting layer 630, and the counter electrode 640 in the region where the transparent electrode 620 and the counter electrode 640 overlap.

In the organic EL display device, at least one electrode needs to be transparent in order to extract light from the organic light emitting layer 630. Therefore, typically, the transparent electrode 620 is comprised from the ITO (Indium Tin Oxide) film which is a transparent conductive film, and is used as an anode. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode. Therefore, typically, the counter electrode 640 is comprised with metal films, such as Mg-Ag and Al-Li, and is used as a cathode.

The organic light emitting layer 630 is a laminate of various organic thin films. In the illustrated example, the organic light emitting layer 630 is made of a hole injectable organic material (for example, triphenylamine derivative), and formed with a hole injection layer 631 formed to improve the hole injection efficiency at the anode, The electron injection layer 632 which consists of the light emitting layer 632 which consists of organic materials (for example, anthracene), and an electron injecting material (for example, a perylene derivative), and was formed in order to improve the electron injection efficiency from a cathode. ) The organic light emitting layer 630 is not limited to the illustrated example, and any suitable combination of organic thin films capable of generating light emission by recombination of electrons and holes in the light emitting layer 632 may be employed.

When a voltage above the threshold is applied between the transparent electrode and the counter electrode, holes are supplied from the anode and reach the light emitting layer 632 via the hole injection layer 631. On the other hand, electrons are supplied from the cathode and reach the light emitting layer 632 via the electron injection layer 633. Energy generated by the recombination of holes and electrons in the light emitting layer 632 excites the light emitting organic material in the light emitting layer, and emits light when the excited light emitting organic material returns from the ground state to emit light. By displaying a voltage for each pixel, the organic light emitting layer emits light, thereby enabling image display. When performing color display, for example, the light emitting layer of three adjacent pixels may be comprised with the luminescent organic substance which shows the light emission of red (R), green (G), and blue (B), respectively, and arbitrary arbitrary You may form a color filter on a light emitting layer.

In such an organic EL display device, the thickness of the organic light emitting layer 630 is preferably as thin as possible. This is because it is preferable to transmit the emitted light as much as possible. The organic light emitting layer 630 may be composed of, for example, a very thin film having a thickness of about 10 nm. As a result, in non-light emission (black state), the light incident on the surface of the transparent substrate 610, transmitted through the transparent electrode 620 and the organic light emitting layer 630, and reflected by the counter electrode 640, It goes out to the surface side of the transparent substrate 610 again. For this reason, when visually recognized from the outside, the display surface of an organic electroluminescence display often looks like a mirror surface. It is preferable to arrange | position a polarizing plate and a retardation plate on the surface of the transparent electrode 620 from a viewpoint of preventing reflection in such a black state. Since the polarizing plate has a function of polarizing light incident on the outside and reflected by the metal electrode, there is an effect that the mirror surface of the display surface is not visually recognized by the polarization action. In particular, by adjusting the angle between the slow axis of the retardation plate and the absorption axis of the polarizing plate to π / 4, and adjusting the phase difference of the entire retardation plate to be 1/4 of the visible wavelength, the mirror surface of the display surface is substantially Can be completely shielded. Specifically, in the organic EL display device in which such a polarizing plate and a retardation plate are arranged, only incident linearly polarized light transmits the incident external light by the polarizing plate. Linear polarization is generally elliptical polarization by the retardation plate, but the phase difference of the whole retardation plate is 1/4 of the visible wavelength, and the angle between the slow axis of the retardation plate and the absorption axis of the polarizing plate is π / 4. In the case of circular polarization. This circularly polarized light penetrates the transparent substrate 610, the transparent electrode 620, and the organic light emitting layer 630, reflects off the counter electrode 640, and then again the organic light emitting layer 630, the transparent electrode 620, and the transparent substrate. 610 is transmitted and linearly polarized light is returned to the retardation plate again. Since this linearly polarized light is orthogonal to the polarization direction of the said polarizing plate, it cannot pass through the said polarizing plate. As a result, the mirror surface of the display surface can be substantially completely shielded.

 Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited at all by these Examples. In addition, the evaluation item in an Example is as follows.

(1) adhesive test

The polarizing plate was cut to 25 x 50 mm, and it was tested whether the polarizer and the transparent protective film could be peeled off by hand at room temperature.

(2) 60 ℃ hot water immersion test

The polarizing plate was cut to 25x50 mm, immersed in 60 degreeC warm water, and time until the protective film of a polarizing plate peeled off was measured.

(3) 90 ℃ durability test

Two polarizing plates were adhere | attached on the glass plate so that the absorption axis of a polarizer might be orthogonal, and after leaving for 90 hours in 90 degreeC oven, light leakage was observed on the backlight.

[Production of Transparent Protective Film a]

One side of the norbornene-based film (manufactured by Nippon Zeon Corporation, trade name "ZEONOR", 40 µm) was subjected to corona treatment with a discharge amount of 200 w · min / m 2. Next, after silicone primer (5 wt% of Nippon Unicar Company make, brand name "APZ-6601") was flexible to the process surface, it heat-processed at 120 degreeC for 30 minutes, and obtained the transparent protective film a of moisture-permeability 0.6g / m <2> / 24h. .

[Production of Transparent Protective Film b]

65 parts by weight of a glutalimide copolymer composed of N-methylglutalimide and methyl methacrylate (content of 75% by weight of N-methylglutalimide, acid content of 0.01 milliequivalents / g or less, glass transition temperature of 147 ° C) And 35 parts by weight of acrylonitrile-styrene copolymer having an acrylonitrile and styrene content of 28% by weight and 72% by weight, respectively. The resin composition obtained by melt-kneading these was extruded with the T die melt extruder, and the film of 135 micrometers in thickness was obtained. The film was stretched 1.7 times at 160 ° C. in the MD direction, and then stretched 1.8 times at 160 ° C. in the TD direction. The thickness of the obtained biaxially stretched transparency film was 50 micrometers. 200 w · min / m 2 of one surface of the transparent protective film Corona treatment was performed with the discharge amount of. Next, after silicone primer (5 wt% of Nippon Unicar Company make, brand name "APZ-6601") was flexible to the process surface, it heat-processed at 120 degreeC for 30 minutes, and obtained the transparent protective film b of moisture permeability 87g / m <2> / 24h.

[Production of Transparent Protective Film c] ·

A triacetyl cellulose film having a water permeability of 900 g / m 2/24 h subjected to a saponification treatment having a thickness of 40 μm was used.

Example 1

Polyvinyl alcohol having a thickness of 75 µm and a polymerization degree of 2400 was stretched 2.5 times while immersing in 30 ° C pure water for 1 minute. Next, it extended | stretched 1.2 times, immersing for 1 minute at 30 degreeC in the dyeing bath of the iodine and potassium iodide combination. Next, it extended | stretched twice, immersing in 60 degreeC 4% boric acid bath for 2 minutes. Furthermore, it was immersed in the aqueous solution of 5% of potassium iodide concentration at 30 degreeC for 5 second, and it dried at 35 degreeC for 5 minutes, and obtained the polarizer. The transparent protective film a was adhere | attached on one side of this polarizer using the PVA-type adhesive agent, and the laminated body was formed. In the case of adhesion | attachment, tension was controlled and bonded so that the laminated body obtained may become flat. After drying the obtained laminated body at 50 degreeC for 5 minutes (that is, without winding up and preserving a laminated body), the transparent protective film c is adhere | attached on the other one surface of a polarizer using a PVA-type adhesive agent, It dried for 5 minutes at 60 degreeC, and 5 minutes at 70 degreeC, and obtained the polarizing plate. In the case of adhesion | attachment, tension was controlled and bonded so that the polarizing plate obtained might become flat. The obtained polarizing plate was used for the adhesion test, the 60 degreeC hot water immersion test, and the 90 degreeC durability test. The results are shown in Table 1 below.

Adhesive test 60 ℃ hot water immersion test 90 ° C durability test (light leakage) Example 1 ○ 6.0h ○ Example 2 ○ 6.0h ○ Comparative Example 1 ○ 1.5h × Comparative Example 2 × - - Comparative Example 3 ○ 2.5h ○ Comparative Example 4 ○ 6.0h ×

Adhesive Test Rating:

(Circle) = It cannot peel. (Good adhesion)

X = could peel. (Adhesion was bad)

Optical Leakage Rating:

(Circle) = light leakage could not be confirmed visually. (Good)

× = Light leakage was visually confirmed. (It was bad)

Example 2

The polarizing plate was produced like Example 1 except having used the transparent protective film b instead of the transparent protective film a. The obtained polarizing plate was used for evaluation similar to Example 1. The results are shown in Table 1.

Comparative Example 1

The polarizer was produced like Example 1, the transparent protective film c was simultaneously adhere | attached on both surfaces using PVA-type adhesive agent, and it dried for 5 minutes at 60 degreeC, and 5 minutes at 70 degreeC, and obtained the polarizing plate. The obtained polarizing plate was used for evaluation similar to Example 1. The results are shown in Table 1.

Comparative Example 2

A polarizer was prepared in the same manner as in Example 1, and the transparent protective film a was simultaneously bonded to both surfaces thereof using a PVA-based adhesive. Got. The obtained polarizing plate was used for evaluation similar to Example 1. The results are shown in Table 1.

Comparative Example 3

A polarizer was prepared in the same manner as in Example 1, and the transparent protective film a and the transparent protective film c were simultaneously bonded using a PVA-based adhesive, and dried at 50 ° C. for 5 minutes, at 60 ° C. for 5 minutes, and at 70 ° C. for 5 minutes. To obtain a polarizing plate. The obtained polarizing plate was used for evaluation similar to Example 1. The results are shown in Table 1.

[Comparative Example 4]

In the same manner as in Example 1, a polarizer was obtained. The transparent protective film c was adhere | attached on one surface of this polarizer using the PVA-type adhesive agent, and the laminated body was formed. In the case of adhesion | attachment, tension was controlled and bonded so that the laminated body obtained may become flat. After drying the obtained laminated body at 50 degreeC for 5 minutes (that is, without winding up and preserving a laminated body), the transparent protective film a is adhere | attached on the other surface of a polarizer using a PVA-type adhesive agent, It dried for 5 minutes at 60 degreeC, and 5 minutes at 70 degreeC, and obtained the polarizing plate. In the case of adhesion | attachment, tension was controlled and bonded so that the polarizing plate obtained might become flat. The obtained polarizing plate was used for evaluation similar to Example 1. The results are shown in Table 1.

As Table 1 shows, it turns out that the polarizing plate of the Example of this invention is excellent in adhesiveness even at high temperature and high humidity compared with the polarizing plate of a comparative example, and light leakage is not recognized. That is, after bonding the 1st transparent protective film which has a water vapor transmission rate of 200 g / m <2> / 24h or less to one surface of a polarizer, and forms a laminated body, the moisture-permeability higher than this 1st transparent protective film is not wound up. By adhering the 2nd transparent protective film which has a to the other surface of the polarizer, peeling and curling at the time of adhesion are prevented, and it turns out that the polarizing plate which is excellent in adhesiveness of a polarizer and a transparent protective film is obtained. Moreover, as can be seen by comparing Example 1 with Comparative Example 4, it is understood that light leakage is improved by adhering a transparent protective film having a relatively high moisture permeability after adhering the transparent protective film having a relatively low moisture permeability.

The polarizing plate of this invention can be used suitably for flat panel displays, such as a liquid crystal display device and a self-luminous display device (for example, organic electroluminescence display).

Claims (11)

After bonding the 1st transparent protective film which has a water vapor transmission rate of 200 g / m <2> / 24h or less to one surface of a polarizer, and forms a laminated body, it does not wind up the said laminated body, but rather than the said 1st transparent protective film The manufacturing method of the polarizing plate containing the process of adhering the 2nd transparent protective film which has high water vapor transmission rate to the other surface of the said polarizer. The method of claim 1, The polarizing plate manufacturing method which affixes the said polarizer and said 1st transparent protective film in the state which provided the tension | tensile_strength to the said polarizer and said 1st transparent protective film. The method of claim 1, The manufacturing method of the polarizing plate which makes the said laminated body and said 2nd transparent protective film adhere | attach in the state which tensioned the said laminated body and said 2nd transparent protective film. The method of claim 1, The curling amount of the said laminated body is 5 mm or less, The manufacturing method of the polarizing plate. The method of claim 1, The amount of curl of the said polarizing plate obtained is 5 mm or less, The manufacturing method of the polarizing plate. The method of claim 1, The said 1st transparent protective film is a polarizing plate manufacturing method which consists of amorphous polyolefin resin. The method of claim 6, The said 2nd transparent protective film is a polarizing plate manufacturing method which consists of triacetyl cellulose. The method of claim 1, The manufacturing method of the polarizing plate further including the process of drying the said laminated body before adhering said 2nd transparent protective film. The polarizing plate obtained by the manufacturing method of Claim 1. The optical element in which one or more optical layers are laminated | stacked on the polarizing plate of Claim 9. The image display apparatus which has a polarizing plate of Claim 9 and / or the optical element of Claim 10.

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