JP2010243863A - Polarizing plate and optical device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate suitably used in a transmissive or reflective liquid crystal display device or the like, which is thin and light-weight and has sufficient durability in a high-temperature and high-humidity severe environment, and an optical device using the polarizing plate. <P>SOLUTION: The polarizing plate 10 comprises a polarizer 1, polymer resin films 5 and 7, and a sealing material 8. In the polarizer 1, a dichroic material is held in a stretched film-like polyvinyl alcohol resin layer and a water content is ≤10% by a mass ratio to a solid component. The polymer resin films 5 and 7 have sealing layers 4 and 6 for blocking intrusion of external materials to the polarizer 1, on at least one principal surfaces thereof and are disposed so as to hold the polarizer 1 in-between. The sealing material 8 is disposed so as to continuously cover a region wherein sealing layers 4 and 6 are not disposed, around the polarizer 1 to form a sealing structure for blocking the intrusion of the external materials to the polarizer 1, together with the sealing layers 4 and 6. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention is a polarizing plate suitably used for a transmissive or reflective liquid crystal display device, and more specifically, a polarizing plate having improved durability under high temperature and high humidity, and the polarizing plate. The present invention relates to an optical device.

  In recent years, image display devices such as a liquid crystal display device (LCD), a plasma display device (PDP), and an electroluminescence display device (ELD) have been widely used. The polarizing plate is widely used as a member constituting these image display devices and optical devices (hereinafter sometimes collectively referred to as optical devices), and is an indispensable member particularly for liquid crystal display devices. A polarizing plate generally used in a liquid crystal display device was manufactured by E.E. H. Invented by Land et al., It is shown in Patent Document 1 described later together with its manufacturing method.

The main part of this polarizing plate is a polarizer obtained by adding a dichroic substance such as iodine or a dichroic dye to a film obtained by uniaxially stretching a resin film made of an elongated chain polymer. In a typical polarizing plate, polyvinyl alcohol (PVA) is used as a chain polymer constituting a resin film, and as a dichroic substance, iodine molecule I ₂ or a combination of n iodine molecules and one iodide ion is bonded. The body polyiodide ion I _{2n + 1} ⁻ is used.

  In order to form the polarizer, first, a thin polymer resin film made of polyvinyl alcohol or the like is formed by a casting method or the like. Next, the polymer resin film is heated to a temperature at which it can be stretched, and then stretched in a certain direction. The heating temperature is lower than the temperature at which fluidity occurs in the resin. If it does in this way, the force which is going to extend the main chain which makes the molecular skeleton of a chain polymer to the above-mentioned fixed direction will act on each chain polymer. As a result, the main chain of each chain polymer constituting the polymer resin film has a three-dimensional configuration along the predetermined direction (hereinafter, the main chain forming the molecular skeleton is referred to as “polymer chain”). The phenomenon in which the polymer chain takes a three-dimensional configuration along a certain direction is abbreviated as “polymer chain orientation”).

  At this time, the polymer chain is oriented by the shearing force of the polymer chain due to stretching. Therefore, generally, the larger the draw ratio for stretching the polymer resin film, the better the alignment of the polymer chains. However, if it is stretched too much, the polymer resin film breaks. For this reason, in patent document 1, in the case of a PVA film, it describes that it is good to extend | stretch about 2.5 to 8 times the original length.

  Next, after returning the polymer resin film to room temperature, it is immersed in a solution in which the dichroic substance is dissolved, so that the polymer resin film contains the dichroic substance to form a polarizer. To do. The order may be reversed, and after the dichroic substance is contained in the polymer resin film, the film may be uniaxially stretched to form a polarizer. Moreover, you may perform simultaneously extending | stretching of a polymer resin film, and addition of a dichroic substance.

  A dichroic substance is a substance composed of molecules or ions having anisotropy in shape and light absorption due to its molecular structure. For example, iodine is a linear colored molecule, has an axially symmetric electron distribution with a straight line connecting the nuclei of two iodine atoms as an axis of rotation, and has an efficiency of absorbing a light component having a vibration vector in the axial direction. This is significantly higher than the efficiency of absorbing a light component having a vibration vector in a direction orthogonal to the axial direction.

  Since the molecules or ions of the dichroic substance have shape anisotropy, they are retained in the oriented polymer resin film with an orientation distribution corresponding to the orientation of the polymer chains. For example, a linear molecule such as iodine is held such that the direction of the molecular axis coincides with the orientation direction of the polymer chain. When molecules or ions of a dichroic material are randomly oriented, such as in the gas phase or liquid phase, the light absorption anisotropy of individual molecules or ions is averaged, and the dichroic material is As a whole, there is no light absorption anisotropy. However, if the molecules or ions of the dichroic substance take an orientation distribution that is biased in a specific direction, as in the oriented polymer resin film, the light absorption anisotropy of each molecule or ion is an average. It is not converted. As a result, the polarizer containing the dichroic substance in the oriented polymer resin film exhibits light absorption anisotropy.

Ordinary light contains components with different vibration vector directions, but when it enters the polarizer, light components whose vibration vector directions coincide with the direction of high light absorption of the dichroic material are efficiently absorbed. On the other hand, the light component whose vibration vector is orthogonal to the above direction is not easily absorbed and passes through. As a result, the light transmitted through the polarizer becomes polarized light. In Patent Document 1, in a polarizer in which polyiodide ions I _{2n + 1} ⁻ are held in a PVA film, the transmittance of normal light is 40% or more, and the degree of polarization of transmitted light is 99.98%. It is described, and high polarization performance can be realized.

  A polarizer made of a uniaxially stretched polymer resin film is likely to undergo dimensional changes due to re-shrinkage of polymer chains over time and changes in environmental conditions such as temperature. When such a dimensional change occurs, the orientation state of the polymer chain also changes and the polarization performance deteriorates. Therefore, a polarizing plate is used in which a protective member such as a transparent glass plate or a resin film is bonded to the main surface of the polarizer as necessary. The role of the protective member is to suppress the dimensional change of the polarizer caused by the passage of time and changes in environmental conditions such as temperature, prevent the dissipation of dichroic material, protect the polarizer from scratches, etc. These include facilitating transport and handling, and protecting the polarizer from contact with harmful components in the atmosphere.

  At present, a triacetyl cellulose (TAC) film is used as a protective member in a polarizing plate generally used in a transmissive or reflective liquid crystal display device. Triacetyl cellulose is excellent in that it has high water resistance and does not warp or change quality due to moisture remaining in the polarizer. In addition, a polyethylene terephthalate (PET) film, a cycloolefin-based resin film, and the like have been proposed as protective members. Whichever is used, in order to suppress the change in the dimensions of the polarizer, a corresponding thickness, for example, about several tens of μm is required. The protective member is bonded to the polarizer with a polyvinyl alcohol-based adhesive or the like.

  In a polarizer composed of a PVA film, a large amount of water tends to remain in the polarizer due to the molecular structure of polyvinyl alcohol having a large number of hydroxy groups and the production method produced from an aqueous solution. For this reason, before bonding with a protective member, the drying process for removing a part of residual water | moisture content in a PVA film is performed. When a TAC film is used as the protective member, a heat treatment for reducing moisture in the PVA film is often performed after the TAC film is bonded to the polarizer. At this time, it is suitably utilized that the TAC film has moisture permeability, and excess water in the PVA film is released into the atmosphere through the TAC film.

  Now, the performance of a polarizer made of a PVA film is affected by moisture remaining in the polarizer. This may be because the state of aggregation between the polymer chains changes due to the remaining moisture, and the orientation of the polymer chains changes.

Therefore, for example, in Patent Document 2 described later, the moisture content of the polarizer when the protective layer (the protective member described above) such as a TAC film is bonded to one or both sides of the polarizer made of a PVA film is 5 to 5. There has been proposed a method for manufacturing a polarizing plate in which a polarizer having a transmittance of 35% or more and a polarization degree of 90% or more is prepared by adjusting the content to 30% by mass, more preferably 9 to 27% by mass. In addition, the moisture content of the polarizer is based on the mass A of the polarizer before bonding and the mass B of the polarizer after drying measured after the polarizer was held in a dryer at 120 ° C. for 7 hours. It is obtained by the following formula.
Water content of polarizer = [(A−B) / B] × 100 (mass%)

  According to Patent Document 2, when the moisture content of the polarizer is less than 5% by mass, the polarizer becomes hard, and when the stretching magnification is increased, groove-like irregularities of the record are generated on the surface of the polarizer. is there. On the other hand, when the moisture content of the polarizer exceeds 30% by mass, adhesion failure tends to occur when a protective layer such as a TAC film is bonded, or in the heat treatment after the protective layer is bonded, Unevenness due to decolorization of iodine may occur in the plate surface.

  Further, in Patent Document 3 described later, the moisture content of the polarizing film is set to 10 to 10 prior to bonding of the polarizing film (the above-described polarizer) made of a PVA-based film and the like and the protective film (the above-described protective member). 33% by mass, more preferably 18-30% by mass, still more preferably 22-29% by mass, and the moisture content of the protective film is 1.9-2.6% by mass, more preferably 2.0-2.5%. A method of manufacturing a polarizing plate with a mass% is proposed. In addition, the measuring method of the moisture content rate of a polarizing film (polarizer) is the same as patent document 1 except measuring the mass B after drying after hold | maintaining in a dryer for 10 hours.

According to Patent Document 3, if the water content of the polarizing film is less than 10% by mass, it is difficult to suppress the occurrence of streak-like irregularities or cracks on the surface of the polarizing film. If it exceeds 33% by mass, the optical properties such as the degree of polarization may be deteriorated. In addition, when the moisture content of the protective film is less than 1.9% by mass, it is very difficult to suppress the occurrence of streak-like irregularities on the surface of the polarizing film, and when it exceeds 2.6% by mass. , It becomes difficult to maintain the adhesion between the polarizing film and the protective film, and there is a risk of peeling. At this time, it is preferable that the moisture permeability of the TAC film used as the protective film is about 400 to 1500 g / (m ² · day) because the moisture content can be adjusted relatively easily.

Further, in Patent Document 4 described later, a first transparent protective film (the above-described protective member) is provided on one surface of a polarizer made of a PVA-based film, and a second transparent protective film (the above-described protective member) is provided on the other surface. Member), and a polarizing plate is produced. The moisture content of the polarizer is 14 to 31% by mass, and the water vapor transmission rate of at least one of the first transparent protective film and the second transparent protective film. A method for manufacturing a polarizing plate has been proposed in which the thickness is 150 g / (m ² · day) or less. In addition, the measuring method of the moisture content of a polarizer is the same as patent document 1 except measuring the mass B after drying after hold | maintaining in a dryer for 2 hours.

Patent Document 4 explains as follows. When the moisture content of the polarizer is 13% by mass, many knick defects are generated, making it difficult to use as a polarizing plate. On the other hand, when the water content of the polarizer is 32% by mass, the degree of polarization decreases. In a polarizing plate using a TAC film as a protective film, since the moisture permeability of the TAC film is large, the durability under a high temperature and high humidity environment is not sufficient. On the other hand, when a protective film having a moisture permeability of 150 g / (m ² · day) or less is used, the influence of the moisture concentration in the outside air is less likely to affect the polarizer, and durability in a high-temperature, high-humidity environment. Will improve. Moreover, the fall of the polarization performance by drying of the polarizer after bonding a polarizer and a protective film is prevented.

  However, in the case of using a protective film having a low moisture permeability, it is necessary to avoid a decrease in the degree of polarization because the polarizer is in a steamed state due to the contained moisture when the polarizer and the protective film are bonded. For this reason, the lower the adhesive drying temperature, the better, and when the adhesive drying temperature is the same, the lower the water content of the polarizer, the higher the degree of polarization of the polarizing plate.

  On the other hand, Patent Document 5 described later is a polarizing plate suitable for a projection type liquid crystal display device such as a front projector and a rear projector, and includes a transparent substrate on both sides of a polarizing film including a polarizer made of a PVA film or the like. And the polarizing plate characterized by the exposed part of the polarizing plate not coat | covered with the transparent substrate being covered with the sealing material is proposed.

  FIG. 6 is a cross-sectional view showing an example of a typical structure of the polarizing plate disclosed in Patent Document 5. FIG. 6A shows an example of a polarizing plate 100 without a protective film. In the polarizing plate 100, both main surfaces of the polarizer 101 are bonded to the transparent substrates 102 and 103 via resin layers 104 and 105, which are adhesive layers, respectively. The end face (side face) of the polarizer 101 and the end faces of the resin layers 104 and 105 that are not bonded to the transparent substrates 102 and 103 are covered with the sealing material 106. FIG.6 (b) is sectional drawing which shows the example of the polarizing plate 200 with a protective film. In the polarizing plate 200, the polarizer 201 is sandwiched between the protective films 202 and 203, and the whole is bonded to the transparent substrates 102 and 103 by an adhesive layer (not shown). And the area | region which is not joined to the transparent substrates 102 and 103 of the edge part of the polarizer 201 and the edge part of the protective films 202 and 203 is coat | covered with the sealing material 204. FIG.

  The transparent substrates 102 and 103 are usually inorganic material substrates, and one is a transparent substrate having a thermal conductivity of 5 W / mK or more, and the other is preferably a transparent substrate having a front phase difference of less than 5 nm.

  Patent Document 5 explains as follows. In the polarizing plate suitable for the projection type liquid crystal display device provided with the transparent substrates 102 and 103 having good thermal conductivity in contact with both main surfaces of the polarizing plate, the cause of weakening the light resistance of the polarizer is in the polarizer. The inventor has discovered that there is a trace amount of moisture present. The transparent substrates 102 and 103 are usually inorganic material substrates that do not allow moisture to pass therethrough. Therefore, the end face or the end of the polarizing plate that is not covered with the transparent substrate is covered with a sealing material, and moisture in the outside air is prevented from entering the polarizer, thereby significantly improving light resistance. At this time, the water content of the polarizer is preferably 5% by mass or less, more preferably 1% by mass or less. In a polarizer in which a dichroic dye is held in polyvinyl alcohol, when the water content is 5% by mass or less, decomposition of the dye is remarkably suppressed, and the light resistance of the polarizing plate is greatly improved.

  In recent years, liquid crystal display devices have been used as display devices for various electronic devices such as personal computer monitors, televisions, and mobile devices. At this time, a liquid crystal display device having a structure optimized for each use environment is manufactured according to the environment used. As described above, as the structure of the liquid crystal display device is diversified, optical characteristics, durability, thickness, and the like required for the constituent members are variously changed. In particular, in order to reduce the thickness of liquid crystal display devices, issues such as higher brightness, higher contrast, improved viewing angle characteristics, thinner display devices, and longer lifespan are becoming more severe. . In addition, liquid crystal display devices for mobile phones have been highly integrated, and it is necessary to pay great attention to waste heat and the like, which can be exposed to high temperatures. Accordingly, even a polarizing plate used in a transmissive or reflective liquid crystal display device is not only thin and lightweight, but also has sufficient polarization degree characteristics, optical characteristics, and shape in a harsh environment of high temperature and high humidity. There is a need to produce a highly durable polarizing plate that can maintain stability.

  On the other hand, conventionally, regarding the design of the polarizing plate, two different policies, specifically three different policies, are shown depending on the use environment.

  That is, in a polarizing plate used in a transmissive or reflective liquid crystal display device and used near room temperature, as shown in Patent Documents 2 to 4, importance is placed on being thin and lightweight, and the thin and lightweight protective member is used. The transparent protective film is used. The appropriate moisture content of the polarizer is about 5 to 33% by mass from the claims of Patent Documents 2 to 4, but about 15 to 30% by mass from the examples shown in Patent Documents 2 to 4. It is estimated to be.

  In Patent Documents 2 and 3, an organic resin film having an appropriate moisture permeability, such as a TAC film, is used as a transparent protective film, and the moisture content of the polarizer becomes an appropriate size due to an appropriate connection with the atmosphere. Expected. Durability in harsh environments of high temperature and high humidity has not been studied.

  In contrast, in Patent Document 4, unlike Patent Documents 2 and 3, an organic resin film having a low moisture permeability is used as a protective film, and the moisture content of the polarizer is reduced by blocking between the polarizer and the outside air. The design policy of the polarizing plate to keep constant is shown. However, the organic resin film cannot completely block between the polarizer and the outside air. Therefore, it is not possible to expect sufficient durability when the polarizing plate proposed in Patent Document 4 is left in a harsh environment of high temperature and high humidity for a long time.

  On the other hand, in a polarizing plate used in a projection type liquid crystal display device and exposed to a high temperature, heat resistance is important, and a polarizer is sandwiched between two transparent inorganic substrates having good thermal conductivity. In this case, according to Patent Document 5, the water content of the polarizer is 5% by mass or less, more preferably 1% by mass or less. In order to realize this, in the polarizing plate shown in Patent Document 5, the end face or the end of the polarizer, which is not covered with the transparent inorganic substrate, is covered with a sealing material, and moisture in the atmosphere is applied to the polarizer. Designed to prevent intrusion.

  As described above, in order to realize sufficient durability under various environments including high temperature and high humidity, as shown in Patent Document 5, the polarizer and the outside air are completely separated by the sealing structure. It is considered necessary to shut off. However, the sealing structure shown in Patent Document 5 is premised on a structure in which a polarizer is sandwiched between transparent inorganic substrates that do not allow moisture to pass through. Since the transparent inorganic substrate is thick and heavy, it cannot be used as a polarizing plate member that is strongly required to be thin and light.

  The present invention has been made in view of such a situation, and an object of the present invention is a polarizing plate suitably used for a transmissive or reflective liquid crystal display device, etc., which is thin and lightweight, and has a high temperature. Another object of the present invention is to provide a polarizing plate having sufficient durability under a severe environment of high humidity, and an optical device using the polarizing plate.

That is, the present invention
A polarizer having a dichroic substance held in a stretched film-like or sheet-like polyvinyl alcohol-based resin layer and having a moisture content of 10% or less by mass ratio to a solid component;
A polymer resin member provided with a sealing layer that prevents entry of an external substance into the polarizer on at least one main surface, and disposed so as to directly or indirectly sandwich the polarizer;
A sealing structure that is disposed so as to continuously cover a region where the sealing layer is not disposed around the polarizer, and prevents entry of an external substance into the polarizer, and the sealing layer. The first polarizing plate having a sealing material to be formed.

The present invention also provides:
A polarizer having a dichroic substance held in a stretched film-like or sheet-like polyvinyl alcohol-based resin layer and having a moisture content of 10% or less by mass ratio to a solid component;
An optical device comprising a sealing layer that prevents entry of an external substance into the polarizer on at least one main surface, and disposed on one surface side of the polarizer on the other surface side of the polarizer A polymer resin member disposed so as to directly or indirectly sandwich the polarizer together with the transparent substrate of
A sealing structure that is disposed so as to continuously cover a region where the sealing layer and the transparent substrate are not disposed around the polarizer, and prevents entry of an external substance into the polarizer. The present invention relates to a second polarizing plate having a sealing layer and a sealing material formed together with the transparent substrate.

  In addition, the present invention relates to an optical device provided with the first polarizing plate or the second polarizing plate as a member for controlling light transmitted or emitted.

  In the first polarizing plate of the present invention, the polymer resin member having the sealing layer on at least one main surface is provided so as to directly or indirectly sandwich the polarizer. Accordingly, the sealing layer is disposed opposite to the main surface (main surface) of the polarizer. And the said sealing material is arrange | positioned in the area | region where the said sealing layer is not arrange | positioned by the side of the said polarizer. Thus, the sealing structure that continuously surrounds the periphery of the polarizer by the sealing layer and the sealing material and prevents external substances such as moisture and oxygen from entering the polarizer. Is formed. With this sealing structure, the moisture content of the polarizer is kept constant, and dimensional changes and hue changes due to moisture absorption are prevented. As a result, in the first polarizing plate of the present invention, sufficient durability under a harsh environment of high temperature and high humidity is obtained, compared with a polarizing plate in which a polymer resin film is used alone as a protective member. Reliability. Under the present circumstances, the water content of the said polarizer is 10% or less by mass ratio with respect to a solid component. As shown in Examples described later, when this condition is satisfied, a polarizing plate having a high dimensional stability of the polarizer and a sufficiently high degree of polarization can be obtained.

  At this time, the polymer resin member is much thinner and lighter than a thick and heavy transparent inorganic substrate as disclosed in Patent Document 5. Further, since a thin layer is sufficient as the sealing layer, the increase in thickness and weight due to the provision of the sealing structure is slight. Therefore, the first polarizing plate of the present invention is thin and light, and is suitable as a polarizing plate constituting a transmissive or reflective liquid crystal display device that is strongly required to be thin and light.

  In the second polarizing plate of the present invention, the polymer resin member having the sealing layer on at least one main surface sandwiches the polarizer directly or indirectly together with the transparent substrate of the optical device. It is provided to do. Therefore, the sealing layer or the transparent substrate is disposed around the main part of the polarizer. And the said sealing material is arrange | positioned in the area | region where the said sealing layer or the said transparent base material is not arrange | positioned around the said polarizer. As described above, the sealing layer, the transparent substrate, and the sealing material continuously surround the polarizer, and prevent external substances such as moisture and oxygen from entering the polarizer. A sealing structure is formed. As a result, in the second polarizing plate of the present invention, sufficient durability under a harsh environment of high temperature and high humidity is obtained, compared with a polarizing plate in which a polymer resin film is used alone as a protective member. Reliability.

  In the second polarizing plate of the present invention, among the polymer resin members constituting the first polarizing plate of the present invention, the polymer resin member on the other side sandwiching the polarizer is omitted. Has been. Instead, the transparent substrate, which is a part of the optical device on which the polarizing plate is mounted, is used, and the holding structure for holding the polarizer in a sandwiched manner, and an external substance entering the polarizer The sealing structure for blocking is formed. Thus, the second polarizing plate of the present invention is integrated with the optical device. As a result, as compared with the first polarizing plate of the present invention, the configuration is simplified, and the thickness and weight are reduced. Other features are the same as those of the first polarizing plate of the present invention.

  In the 1st or 2nd polarizing plate of this invention, as a result of providing the said sealing layer, the effect that the restriction | limiting with respect to the material of the said polymeric resin member reduces is also acquired. For example, since the polymer resin member does not need to have a sealing performance, unlike the polarizing plate disclosed in Patent Document 4, the material of the polymer resin member may be limited to a material having low moisture permeability. Absent. In addition, conventionally, the material of the protective member has been practically limited to triacetyl cellulose (TAC) having high water resistance so that it is not warped or altered by moisture remaining in the polarizer. . On the other hand, in the first and second polarizing plates of the present invention, the sealing layer is disposed so as to be interposed between the polarizer and the polymer resin member, and the sealing layer is interposed between the two. In this case, the polymer resin member does not need to have high water resistance.

  Since the optical device of the present invention includes the first polarizing plate of the present invention or the second polarizing plate of the present invention as a member for controlling light transmitted or emitted, it is a severe environment of high temperature and high humidity. Sufficient durability is obtained even below, and the reliability is improved as compared with an optical device using a polarizing plate in which a polymer resin film is used alone as a protective member. Further, it is thinner and lighter and more convenient than an optical device using a polarizing plate in which a transparent inorganic substrate is used as a protective member.

It is sectional drawing which shows the structure of the polarizing plate based on Embodiment 1 of this invention. It is sectional drawing which shows the structure of the polarizing plate based on Embodiment 2 of this invention. It is sectional drawing which shows the structure of the liquid crystal display device based on Embodiment 3 of this invention. It is a graph which shows the relationship between the moisture content of the polarizer and the dimensional change rate by experiment of the Example of this invention. It is a graph which shows the relationship between the moisture content of the polarizer and polarization degree by experiment of the Example of this invention. It is sectional drawing which shows the example of the typical structure of the polarizing plate shown by patent document 5. FIG.

  Hereinafter, embodiments of the present invention will be described in detail, but the present invention is not limited to these examples.

  In the first and second polarizing plates of the present invention, the water content of the polarizer is preferably 10% by mass or less, more preferably 5% by mass or less.

  Moreover, it is preferable that the sealing layer is provided on at least a main surface close to the polarizer among the two main surfaces of the polymer resin member.

The sealing layer may be a single layer or a plurality of layers, and at least one layer thereof may be a dense layer made of an inorganic compound. This inorganic compound is, for example, silicon nitride SiN, silicon oxide SiO ₂ , silicon oxynitride SiON, silicon oxide silicon SiOC, silicon nitride carbide SiNC, lithium fluoride LiF, tin (IV) SnO ₂ , or aluminum oxide (alumina) Preferably it is Al ₂ O ₃ .

  The sealing layer may be a single layer or a plurality of layers, and at least one layer thereof may be a dense layer made of parylene or an organic / inorganic hybrid material.

  The sealing material may be made of an ultraviolet curable resin. The ultraviolet curable resin may be an ultraviolet curable epoxy resin or an acrylic resin.

  The polymer resin member may be made of triacetyl cellulose resin, polyether sulfone resin, polycarbonate resin, cycloolefin polymer resin, polyethylene terephthalate resin, or polyethylene naphthalate resin.

  The optical device of the present invention is preferably configured as a liquid crystal display device.

  Next, a preferred embodiment of the present invention will be described more specifically with reference to the drawings.

[Embodiment 1]
In the first embodiment, an example of the first polarizing plate of the present invention corresponding to claims 1 and 3 to 11 will be described.

  FIG. 1A is a cross-sectional view showing the structure of a polarizing plate based on the first embodiment. In this polarizing plate 10, a polymer resin film 5 in which the sealing layer 4 is provided on one main surface and a polymer resin film 7 in which the sealing layer 6 is provided on one main surface are the polarizer 1. Are bonded to the upper and lower main surfaces of the polarizer 1 by the adhesive layers 2 and 3, respectively.

  The polarizer 1 is a polarizer having a known configuration in which a dichroic substance such as iodine is held in a stretched film-like or sheet-like polyvinyl alcohol resin layer. However, as a feature of the present embodiment, the water content of the polarizer 1 is 10% by mass or less, more preferably 5% by mass or less. As shown in the examples described later, when this condition is satisfied, a polarizing plate 10 having a high dimensional stability of the polarizer 1 and a sufficiently large degree of polarization can be obtained.

  As a feature of the polarizing plate according to the present invention, the polarizer 1 has a sealing structure. That is, the sealing layer 4 and the sealing layer 6 are disposed on the main surface (two main surfaces) of the polarizer 1 so as to face each other. And the sealing material 8 is arrange | positioned in the area | region (edge part) around the polarizer 1 in which the sealing layer 4 and the sealing layer 6 are not arrange | positioned. As described above, the sealing layers 4 and 6 and the sealing material 8 continuously surround the periphery of the polarizer 1 and prevent an external substance such as moisture and oxygen from entering the polarizer 1. Is formed. With this sealing structure, the moisture content of the polarizer 1 is kept constant, and dimensional changes and hue changes due to moisture absorption are prevented. As a result, the polarizing plate 10 has sufficient durability even in a severe environment of high temperature and high humidity, and is more reliable than a conventional polarizing plate in which a polymer resin film is used alone as a protective member. Improves.

  At this time, the polymer resin films 5 and 7 are much thinner and lighter than a thick and heavy transparent inorganic substrate as shown in Patent Document 5. Further, since the sealing layers 4 and 6 are sufficient as thin layers, the increase in thickness and weight due to the provision of the sealing structure is slight. Accordingly, the polarizing plate 10 is suitable as a polarizing plate constituting a transmissive or reflective liquid crystal display device that is thin and light and is strongly required to be thin and light.

  FIG. 1B is a cross-sectional view showing the structure of polarizing plate 11 based on a modification of the first embodiment. In the polarizing plate 11, the polymer resin films 5 and 7 are slightly larger than the polarizer 1, and the sealing layer 4 and the sealing layer 6 can be bonded at the end of the polarizer 1. ing. As a result, since the area where the sealing material 8 is exposed to the outside air is reduced, the sealing performance is improved as compared with the polarizing plate 10.

  The polarizing plate 10 shown in FIGS. 1 (a) and 1 (b) corresponds to claim 5 and, of the two main surfaces of the polymer resin film 5 (and 7), the main surface closer to the polarizer 1 is present. In this example, the sealing layer 4 (and 6) is provided on the surface. On the other hand, the polarizing plate 12 shown in FIG. 1C has the sealing layer 4 (and 6) on the main surface far from the polarizer 1 out of the two main surfaces of the polymer resin film 5 (and 7). ). The surface on which the sealing layer is provided may be either of the two main surfaces, or may be provided on both main surfaces. However, as can be seen from the comparison between the polarizing plate 10 and the polarizing plate 12, the sealing structure can be formed more compactly by providing the sealing layer on the main surface closer to the polarizer 1. Moreover, since the penetration | invasion of the substance discharge | released from the polymer resin film 5 (and 7) can also be prevented, it is more effective. Further, since mechanical damage to the sealing layer 4 (and 6) due to external force is prevented by the polymer resin film 5 (and 7), the sealing layer 4 (and 6) is formed inside like the polarizing plate 10. The polymer resin film 5 (and 7) on the outside is preferred.

The sealing layers 4 and 6 are composed of a single layer or a plurality of layers, and at least one layer thereof is preferably a dense layer composed of an inorganic compound. This inorganic compound is, for example, silicon nitride SiN, silicon oxide SiO ₂ , silicon oxynitride SiON, silicon oxide carbide SiOC, silicon nitride carbide SiNC, lithium fluoride LiF, tin oxide (IV) SnO ₂ , or aluminum oxide (alumina) Preferably it is Al ₂ O ₃ . Among these, the SiN layer, the SiO ₂ layer, and the SiON layer are preferably formed by a plasma CVD (Chemical Vapor Deposition) method, and the LiF layer and the SnO ₂ layer are preferably formed by an evaporation method, and Al ₂ O _3. The layer is preferably formed by a sputtering method.

  In particular, a silicon nitride layer formed by a plasma CVD method has high density and exhibits high sealing performance. In addition, the lithium fluoride layer can be formed by resistance heating vapor deposition, and has an advantage that damage to the polymer resin films 5 and 7 at the time of formation is small. Moreover, since the light transmittance in the visible light region is high, it is suitable when it is necessary that the light transmittance is excellent.

  Alternatively, the sealing layers 4 and 6 are formed of a single layer or a plurality of layers, and at least one layer thereof is preferably a dense layer formed of parylene or an organic / inorganic hybrid material. Further, it is more preferable that a layer made of parylene or an organic / inorganic hybrid material is laminated on the inorganic compound layer. These organic compound layers are flexible, are not prone to cracking, prevent cracking in the inorganic compound layer, and prevent cracks from penetrating the sealing layer even when cracking occurs. It works to improve the sealing performance.

  Parylene is a general term for paraxylylene resins and has a polyparaxylylene skeleton. In addition to polyparaxylylene, materials in which some hydrogen atoms are replaced by chlorine atoms or fluorine atoms, such as poly (monochloroparaxylylene), have been put into practical use. The parylene layer is a material having an excellent barrier property against water vapor. The parylene layer can be formed by a CVD method, and has the advantage that damage to the polymer resin films 5 and 7 is small and can be formed with good coverage.

  The organic / inorganic hybrid material is, for example, a coating material disclosed in Japanese Patent Application Laid-Open No. 2008-36914. This coating material includes a water-soluble polymer (A) having a hydroxy group such as polyvinyl alcohol (PVA), a water-soluble polymer (B) having a carboxy group such as polyacrylic acid (PAA), and silicon or metal. An alkoxide and / or a hydrolysis condensate thereof (C), wherein the weight ratio of (A) to (B) is 97/3 to 3/97, and the content of (C) is ( It is obtained by curing a coating composition, which is 1 part by weight or more and 450 parts by weight or less with respect to a total of 100 parts by weight of A) and (B). In this coating material, the PVA polymer (A) and the PAA polymer (B) are condensed by an ester bond, and the organic polymer and the siloxane polymer form a phase separation structure on the order of several tens of nm. Therefore, it has flexibility and barrier properties.

  As an effect obtained by providing the sealing layers 4 and 6, in addition to the above effects, there is an effect that restrictions on the materials of the polymer resin films 5 and 7 are reduced. For example, since the polymer resin films 5 and 7 do not need to have sealing performance, the material of the polymer resin films 5 and 7 is limited to a material with low moisture permeability unlike the polarizing plate disclosed in Patent Document 4. It will not be done.

  Moreover, when the sealing layers 4 and 6 are arrange | positioned so that it may interpose between the polarizer 1 and the polymer resin films 5 and 7 like the polarizing plate 10, the polarizer 1 and the polymer resin film Since the space between 5 and 7 is blocked by the sealing layers 4 and 6, the polymer resin films 5 and 7 do not need to have high water resistance. For this reason, unlike the past, the polymer resin films 5 and 7 are not substantially limited to the TAC film.

  On the other hand, the polymer resin films 5 and 7 must have a property that the sealing layers 4 and 6 can be reliably formed on the surface, for example, heat resistance that does not cause a problem in the formation process of the sealing layers 4 and 6. become. As materials for the polymer resin films 5 and 7, among materials satisfying this condition, those having excellent optical performance, those having excellent environmental resistance, those having a low environmental load, those readily available, An appropriate material can be appropriately selected and used in accordance with required characteristics such as an inexpensive one.

  Examples of resin materials having excellent light transmittance with respect to visible light include triacetyl cellulose (TAC) resin, polyether sulfone (PES) resin, polycarbonate (PC) resin, cycloolefin polymer resin, and polyethylene terephthalate (PET). Examples thereof include a resin and a polyethylene naphthalate (PEN) resin. Examples of the cycloolefin polymer resin include zeonore resin (trade name; manufactured by Nippon Zeon Co., Ltd.) which is a cycloolefin polymer (COP), and appel resin (trade name; manufactured by Mitsui Chemicals, Inc.) which is a cycloolefin copolymer (COC). is there.

  However, when the polarizing plates 10 to 12 are polarizing plates for a liquid crystal display device, a material having a large birefringence, such as a polyethylene naphthalate (PEN) resin, cannot be used. This is because if a material having a large birefringence is used, linearly polarized light becomes elliptically polarized light, which causes a problem that the contrast of the display image is lowered or the display image is blurred. Examples of the resin material having no birefringence include polyethersulfone (PES) resin. In addition, a composite material by a crystal dope method in which inorganic fine particles having reverse birefringence are added to an organic polymer resin having birefringence so as to cancel the birefringence of the organic polymer resin. It can also be used.

  The materials of the adhesives 2 and 3 are not particularly limited, and examples thereof include acrylic resins, silicone resins, polyester resins, polyurethane resins, polyamide resins, polyether resins, fluorine resins, and rubber resins. Those using a polymer resin as a base material can be appropriately selected and used. In particular, a material that has excellent optical transparency, moderate wettability, cohesiveness and adhesive properties, and excellent weather resistance, heat resistance, and the like, such as an acrylic pressure-sensitive adhesive, is preferably used. Can do.

  The sealing material 8 is preferably made of an ultraviolet curable resin. In this case, curing can be easily controlled by light irradiation. As the ultraviolet curable resin, by using a resin that generates less gas and has a small shrinkage during curing, for example, an epoxy resin or an acrylic resin, it is possible to suppress deterioration of the characteristics of the polarizer 1 in the bonding step. Epoxy resins are particularly preferable because they are excellent in material stability after curing. In addition, the sealing material 8 is not restricted to an ultraviolet curable resin, A thermosetting resin can also be used.

  In the polarizing plates 10 to 12, the polymer resin films 5 and 7 provided with the sealing layers 4 and 6 are provided so as to sandwich only the polarizer 1 except for the adhesive layers 2 and 3. ing. In this case, in the present invention, it is expressed as “the polymer resin films 5 and 7 directly sandwich the polarizer 1”. The present invention is not limited to this case. For example, a retardation film may be provided between the polarizer 1 and the polymer resin film 5 or 7. In such a case, the present invention is expressed as “the polymer resin films 5 and 7 indirectly sandwich the polarizer 1”.

[Embodiment 2]
In the second embodiment, an example of the second polarizing plate of the present invention corresponding to claims 2 to 11 will be described.

  FIG. 2A is a cross-sectional view showing the structure of a polarizing plate based on the second embodiment. In the polarizing plate 20, a polymer resin film 5 in which the sealing layer 4 is provided on one main surface is disposed on one surface side of the polarizer 1. A transparent substrate 23 constituting the liquid crystal cell 26 is disposed on the other surface side of the polarizer 1. The polymer resin film 5 and the transparent substrate 23 are disposed so as to directly sandwich the polarizer 1, and are respectively attached to the upper and lower main surfaces of the polarizer 1 by adhesive layers 2 and 3.

  The liquid crystal cell 26 corresponds to the optical device, and the transparent substrate 23 corresponds to the transparent base material. The liquid crystal cell 26 is formed by a liquid crystal layer 22, transparent substrates 23 and 24 that sandwich the liquid crystal layer 22, a sealing material 25, and the like.

  In the polarizing plate 20, the polymer resin film 7 is omitted from the polymer resin films 5 and 7 constituting the polarizing plate 10 described in the first embodiment. Instead, a transparent substrate 23 which is a part of the liquid crystal cell 26 to which the polarizing plate 20 is mounted is used, and a holding structure for holding the polarizer 20 in a sandwiched manner and an external substance to enter the polarizer 20. A blocking structure is formed.

  That is, the polarizer 1 is the same as the polarizer 1 of the polarizing plate 10. On the main surface (two main surfaces) of the polarizer 1, the sealing layer 4 and the transparent substrate 23 are arranged to face each other. And the sealing material 8 is arrange | positioned in the area | region (edge part) around the polarizer 1 where the sealing layer 4 and the transparent substrate 23 are not arrange | positioned. As described above, the sealing layer 4, the transparent substrate 23, and the sealing material 8 continuously surround the periphery of the polarizer 1, and seal the outside substance such as moisture and oxygen from entering the polarizer 1. A stop structure is formed. With this sealing structure, the moisture content of the polarizer 1 is kept constant, and dimensional changes and hue changes due to moisture absorption are prevented. As a result, the polarizing plate 20 has sufficient durability even under a severe environment of high temperature and high humidity, and is more reliable than a conventional polarizing plate in which a polymer resin film is used alone as a protective member. Will improve.

  Thus, the polarizing plate 20 is basically designed according to the same design policy as the polarizing plate 10. Then, by being integrated with the liquid crystal cell 26, the sealing layer 6 and the polymer resin film 7 are omitted, and as a result, the configuration is simplified and the thickness and weight are reduced compared to the polarizing plate 10. .

  The polarizing plate 21 shown in FIG. 2 (b) corresponds to the polarizing plate 12 of the first embodiment, and on the main surface far from the polarizer 1 out of the two main surfaces of the polymer resin film 5, This is an example in which a sealing layer 4 is provided. The surface on which the sealing layer is provided may be either of the two main surfaces, or may be provided on both main surfaces, but as described above, the arrangement of the polarizing plate 20 is preferable to the arrangement of the polarizing plate 21. .

  Since the other characteristics of the polarizing plates 20 and 21 and the selection of the constituent materials are as described in the first embodiment, the description is omitted to avoid duplication.

  The material of the transparent substrate 23 may be any material that has a high light transmittance and does not allow moisture to pass through. For example, a glass substrate used in a normal liquid crystal cell is preferable. Moreover, the transparent resin substrate which formed the sealing layer similar to the sealing layer 4 on the surface may be sufficient. In this case, not only can the liquid crystal cell 26 be reduced in weight, but if a flexible resin substrate is used, a flexible image display device that can be arranged on a curved surface or can have various shapes can be configured. it can.

[Embodiment 3]
In the third embodiment, an example of the liquid crystal display device described in claims 12 and 13 will be described.

  FIG. 3 is a schematic cross-sectional view showing a configuration of a transmissive liquid crystal display device 50 according to Embodiment 3 of the present invention. As shown in FIG. 3, the transmissive liquid crystal display device 50 includes a liquid crystal display panel 40 and a backlight device 30 that irradiates illumination light on the back side (lower side in FIG. 3).

  In the liquid crystal display panel 40, a liquid crystal cell is formed by a liquid crystal layer 41 and a pair of transparent substrates 42 and 43 facing each other with the liquid crystal layer 41 interposed therebetween, and a pair of polarizing plates 46 and 47 on the outer surface side of the transparent substrates 42 and 43. Further, optical compensation films 44 and 45 are disposed between the transparent substrates 42 and 43 and the polarizing plates 46 and 47, respectively.

  The configuration of the liquid crystal layer 41 is not particularly limited, and is a liquid crystal material in which the dielectric anisotropy is positive and the molecular long axis is aligned substantially parallel to the electric field direction when an electric field is applied, or the molecular long axis when the dielectric anisotropy is negative and the electric field is applied. A vertical alignment type liquid crystal material or the like that is aligned substantially perpendicular to the electric field direction is used.

  The transparent substrates 42 and 43 are made of a glass substrate, and although not shown in the figure, a striped transparent electrode, an insulating film, and an alignment film are formed on the inner surface of the transparent substrate 42. A color filter of three primary colors of red (R), green (G), and blue (B), an overcoat layer, a striped transparent electrode, and an alignment film are formed. The alignment film is made of polyimide, for example, and is provided in contact with the liquid crystal material.

  The optical compensation films 44 and 45 cancel the phase difference between the light waves caused by the light having different wavelengths passing through the liquid crystal layer 41, and prevent the liquid crystal layer from being colored. That is, it cancels the wavelength dispersion characteristic of the liquid crystal layer 41 and functions to realize an achromatic background display. In addition, it decreases the brightness, chromaticity, and contrast of the liquid crystal display device due to the difference in viewing angle, thereby improving the viewing angle characteristics of the liquid crystal display device 50.

  The backlight device 30 is generally configured by appropriately combining a backlight light source 33 and a diffusion plate 34, a diffusion sheet 35, a prism sheet 36, a polarization separation element 37, and the like disposed on the light emission side.

  The backlight light source 33 is a direct type backlight light source that emits illumination light from the back side of the liquid crystal display panel 40. The backlight light source 33 includes, for example, a linear light source 31 composed of a plurality of cold cathode tubes, a reflecting plate 32 that covers the back side and the side of the linear light source 31, and the like. Light emitted from the backlight light source 33 (backlight light) is incident on the liquid crystal display panel 40 via various optical films 34 to 37.

  The diffuser plate 34 scatters the light emitted from the backlight light source 33 (backlight light), averages the variation of the light path, and uniforms the luminance, and the backlight source 33 from the liquid crystal display panel 40 side. Make the bright lines invisible. The diffusion sheet 35 diffuses the backlight light in a predetermined angle range. The prism sheet 36 has a function of condensing the backlight light diffused by the diffusion sheet 35 and causing it to enter the polarization separation element (brightness enhancement film) 37. The polarization separation element 37 transmits a linearly polarized component in a certain direction included in incident light, and reflects other linearly polarized components. As a result, only polarized light in a certain direction enters the liquid crystal display panel 40.

  The polarized light that has passed through the polarization separation element 37 passes through the polarizing plate 46 having a transmission axis parallel to the polarization direction, and enters the liquid crystal layer 41 through the optical compensation film 44 and the transparent substrate 42. The liquid crystalline molecules constituting the liquid crystal layer 41 are driven by the voltage applied between the electrodes for each pixel region sandwiched between the transparent electrodes, the orientation direction is controlled, and the polarization direction of the incident light is the liquid crystal While passing through the layer 41, it is changed by the above-mentioned aligned liquid crystal molecules. As a result, the amount of light transmitted through the polarizing plate 47 on the front surface side of the liquid crystal display panel 40 is controlled for each pixel, and an image is formed on the front surface of the liquid crystal display panel 40.

  In the transmissive liquid crystal display device 50, as the polarizing plates 46 and 47, polarizing plates based on the present invention, for example, the polarizing plates 10 to 12 shown in the first embodiment are used. Alternatively, the polarizing plate 20 or 21 shown in the second embodiment may be used and integrated with the transparent substrates 42 and 43. As a result, sufficient durability is obtained even in a severe environment of high temperature and high humidity, and the reliability is improved as compared with an optical device using a polarizing plate in which a polymer resin film is used alone as a protective member. Further, it is thinner and lighter and more convenient than an optical device using a polarizing plate in which a transparent inorganic substrate is used as a protective member.

  Hereinafter, in order to clarify the preferable water content of the polarizer, a polarizing plate having the same structure as that of the polarizing plate 10 shown in FIG. 1A is prepared, and the water content of the polarizer 1 and before and after the high temperature durability test are prepared. The experiment of the Example which investigated the relationship between the dimensional change rate of the polarizer 1 and the polarization degree of the polarizing plate after the high-temperature durability test will be described. In addition, since the objective of this experiment is to clarify the preferable moisture content of the polarizer, the sealing layers 4 and 6 are respectively provided on glass plates that are known to be able to reliably prevent the transmission of moisture. The polymer resin films 5 and 7 were used instead.

[Example 1]
<Preparation of polarizing plate>
First, polyvinyl alcohol having a polymerization degree of 1700 and a saponification degree of 99.7% was dissolved in water to prepare an aqueous solution. A thin film made of polyvinyl alcohol was formed from this aqueous solution by a casting method. After the film formation, the film was dried to obtain a PVA film having a thickness of 75 μm.

Next, an iodine aqueous solution in which iodine I ₂ , potassium iodide KI, and boric acid H ₃ BO ₃ were dissolved at appropriate concentrations was prepared. The PVA film described above was immersed in this aqueous iodine solution and stretched to a length of about 6 times in the aqueous solution, thereby producing a polarizer 1. The obtained polarizer 1 was blown at 60 ° C. for 30 minutes, the polarizer 1 was dried, and a polarizer 1 in which the moisture content relative to the amount of PVA resin was adjusted to a predetermined size was produced.

  After drying, the polarizer 1 was cut into a square with a side of 30 mm. A square glass plate having a side of 50 mm and a thickness of 0.7 mm was bonded to both main surfaces of the polarizer 1 using an ultraviolet curable acrylic resin as an adhesive. Furthermore, after applying an ultraviolet curable epoxy resin as a sealing material (sealant) to the end, it was cured and sealed, and a polarizing plate having the same structure as the polarizing plate 10 was produced.

<Evaluation of polarizing plate>
The water content of the polarizer 1 was measured by the Karl Fischer method using CA-07 (trade name; manufactured by Mitsubishi Chemical Corporation) under the conditions of heating conditions of 150 ° C. and a baseline of 0.1 μg / min. At this time, the moisture content obtained when the polarizer 1 was heated to 150 ° C. was defined as the moisture content of the polarizer 1.

  A high temperature durability test was performed in which the produced polarizing plate was held in an oven at 85 ° C. for 500 hours, and the dimensional change of the polarizer 1 before and after the high temperature durability test and the polarization characteristics of the polarizer 1 after the high temperature durability test were examined. Polarization characteristics were measured using V-7100 (trade name; manufactured by JASCO Corporation), and the reference light measurement was performed with only two glass plates.

[Example 2]
The polarizer 1 obtained by stretching in an aqueous iodine solution was blown at 80 ° C. for 30 minutes to dry the polarizer 1. Others were produced in the same manner as in Example 1, and the characteristics were examined.

[Example 3]
The polarizer 1 obtained by stretching in an aqueous iodine solution was blown at 90 ° C. for 30 minutes to dry the polarizer 1. Others were produced in the same manner as in Example 1, and the characteristics were examined.

[Example 4]
The polarizer 1 obtained by stretching in an aqueous iodine solution was blown at 100 ° C. for 30 minutes to dry the polarizer 1. Others were produced in the same manner as in Example 1, and the characteristics were examined.

[Example 5]
The polarizer 1 obtained by stretching in an aqueous iodine solution was blown at 100 ° C. for 40 minutes to dry the polarizer 1. Others were produced in the same manner as in Example 1, and the characteristics were examined.

[Example 6]
The polarizer 1 obtained by stretching in an aqueous iodine solution was blown at 100 ° C. for 60 minutes to dry the polarizer 1. Others were produced in the same manner as in Example 1, and the characteristics were examined.

[Example 7]
The polarizer 1 obtained by stretching in an aqueous iodine solution was blown at 100 ° C. for 90 minutes to dry the polarizer 1. Others were produced in the same manner as in Example 1, and the characteristics were examined.

[Example 8]
The polarizer 1 obtained by stretching in an aqueous iodine solution was blown at 110 ° C. for 90 minutes to dry the polarizer 1. Others were produced in the same manner as in Example 1, and the characteristics were examined.

[Example 9]
The polarizer 1 obtained by stretching in an aqueous iodine solution was blown at 60 ° C. for 5 minutes to dry the polarizer 1. After drying, a TAC film having a thickness of 80 μm was bonded to both main surfaces of the polarizer 1 using an aqueous polyvinyl alcohol solution as an adhesive, and dried at 80 ° C. for 30 minutes to produce a polarizing plate. Otherwise, the high temperature durability test was conducted in the same manner as in Example 1. In addition, the water content of the polarizer 1 in Comparative Example 4 was measured in a state where only the polarizer 1 was taken out by peeling off the TAC film.

[Example 10]
After producing a polarizing plate in the same manner as in Comparative Example 9, the TAC film was peeled off and removed, and a high temperature durability test was performed with only the polarizer 1 taken out. The water content of the polarizer 1 in Comparative Example 10 was measured in the state where only the polarizer 1 was taken out, as in Comparative Example 9.

  Table 1 is a table showing the moisture content of the polarizer 1, the dimensional change rate of the polarizer 1 before and after the high temperature durability test, and the polarization degree of the polarizing plate after the high temperature durability test in Examples 1 to 10. In the table, in the pass / fail column, those having a dimensional change of 1% or more of the initial dimension and those having a polarization degree of less than 99% were rejected and indicated by x. Moreover, the thing whose dimensional change amount is less than 1% of an initial dimension, and the thing whose polarization degree is 99% or more were set as the pass, and were shown by (circle).

  FIG. 4 is a graph showing the relationship between the moisture content and the dimensional change rate of the polarizer 1 in Examples 1-8. Moreover, FIG. 5 is a graph which shows the relationship between the moisture content of the polarizer 1 in Examples 1-8, and the polarization degree of a polarizing plate.

  As shown in Table 1 and FIGS. 4 and 5, the smaller the moisture content of the polarizer 1, the smaller the dimensional change rate and the greater the degree of polarization. In particular, when the moisture content is 10% or less, the dimensional change rate before and after the high temperature durability test is suppressed to less than 1.0%, and the polarization degree of the polarizing plate after the high temperature durability test can be secured to 99% or more. ,preferable. Further, in order to obtain a larger degree of polarization, the water content is preferably 5% or less, more preferably 3% or less. However, in order to reduce the moisture content of the polarizer 1, it is necessary to blow and dry the polarizer 1 at a higher temperature for a longer time, and the productivity is lowered. Therefore, the moisture content of the polarizer 1 is preferably set to an appropriate size of 10% or less depending on the required polarization characteristics.

  In this experiment, a blast heating method is used as a drying method, but the drying method is not particularly limited, and a known method can be appropriately used. For example, drying in an inert gas, drying in dry air, heat drying using a heating roll, drying using light heating, treatment in a supercritical state, dehydration by solvent replacement, and moisture absorption materials should be included. Any method may be used such as a drying process in which the material is pressed, or a combination thereof may be used.

  The degree of polymerization of the polyvinyl alcohol resin is not particularly limited, but is preferably 500 to 10000, more preferably 1000 to 6000, considering the solubility of the PVA film in water. The saponification degree of the polyvinyl alcohol resin is preferably 80 or more, more preferably 98 to 100%. The thickness of the film is preferably 10 to 150 μm because if it is too thin, it will break during stretching, and if it is too thick, the polarization characteristics will become uneven.

  Although the present invention has been described based on the embodiments and examples, it is needless to say that the present invention is not limited to these examples and can be appropriately changed without departing from the gist of the invention. . The polarizing plate of the present invention is not limited to the liquid crystal display device described in Embodiment 3, but may be an image display device or an optical device that requires a polarizing plate, such as an electroluminescence display device or a plasma light-emitting display device. Anything can be suitably used.

  According to the polarizing plate of the present invention, it is possible to provide a polarizing plate having improved thermal stability at high temperatures without impairing transparency and polarization characteristics, and devices using a polarizer such as a liquid crystal display device. This can contribute to improvements in durability and reliability.

DESCRIPTION OF SYMBOLS 1 ... Polarizer, 2, 3 ... Adhesive layer, 4 ... Sealing layer, 5 ... Organic polymer resin film,
6 ... sealing layer, 7 ... organic polymer resin film, 8, 9 ... sealing material, 10-12 ... polarizing plate,
20, 21 ... Polarizing plate, 22 ... Liquid crystal layer, 23, 24 ... Transparent substrate, 25 ... Sealing material,
26 ... Liquid crystal cell, 30 ... Backlight device, 31 ... Backlight light source,
31a ... linear light source, 31b ... reflector, 32 ... diffuser plate, 33 ... diffuser sheet,
34 ... Prism sheet, 35 ... Polarization separation element, 40 ... Liquid crystal display panel, 41 ... Liquid crystal layer,
42, 43 ... transparent substrate, 44, 45 ... optical compensation film, 46, 47 ... polarizing plate,
50 ... Transmission type liquid crystal display device, 100 ... Polarizing plate, 101 ... Polarizer,
102, 103 ... transparent substrate, 104, 105 ... resin layer, 106 ... sealing material,
DESCRIPTION OF SYMBOLS 200 ... Polarizing plate, 201 ... Polarizer, 202, 203 ... Protective film, 204 ... Sealing material

U.S. Pat. No. 2,237,567 (first and second pages, FIGS. 1 and 2) JP 2001-296426 A (Claims 1, pages 2, 6 and 7, Table 1) JP 2006-30480 A (Claim 1-3, pp. 3-9, Table 1) JP 2008-296426 (Claim 1, pages 2, 3, 5 and 13-16, Table 1) JP 2008-268842 A (claims 1 and 2, pages 6, 7, 11 and 12, Table 1)

Claims (13)

A polarizer having a dichroic substance held in a stretched film-like or sheet-like polyvinyl alcohol-based resin layer and having a moisture content of 10% or less by mass ratio to a solid component;
A polymer resin member provided with a sealing layer that prevents entry of an external substance into the polarizer on at least one main surface, and disposed so as to directly or indirectly sandwich the polarizer;
A sealing structure that is disposed so as to continuously cover a region where the sealing layer is not disposed around the polarizer, and prevents entry of an external substance into the polarizer, and the sealing layer. A polarizing plate having a sealing material to be formed. A polarizer having a dichroic substance held in a stretched film-like or sheet-like polyvinyl alcohol-based resin layer and having a moisture content of 10% or less by mass ratio to a solid component;
An optical device comprising a sealing layer that prevents entry of an external substance into the polarizer on at least one main surface, and disposed on one surface side of the polarizer on the other surface side of the polarizer A polymer resin member disposed so as to directly or indirectly sandwich the polarizer together with the transparent substrate of
A sealing structure that is disposed so as to continuously cover a region where the sealing layer and the transparent substrate are not disposed around the polarizer, and prevents entry of an external substance into the polarizer. A polarizing plate having a sealing layer and a sealing material formed together with the transparent substrate.   The polarizing plate according to claim 1 or 2, wherein the polarizer has a water content of 10% by mass or less.   The polarizing plate according to claim 3, wherein the water content of the polarizer is 5 mass% or less.   The polarizing plate according to claim 1, wherein the sealing layer is provided on at least a main surface close to the polarizer among the two main surfaces of the polymer resin member.   The polarizing plate according to claim 1, wherein the sealing layer is composed of a single layer or a plurality of layers, and at least one layer thereof is a dense layer composed of an inorganic compound. The inorganic compound is silicon nitride SiN, silicon oxide SiO ₂ , silicon oxynitride SiON, silicon oxide carbide SiOC, silicon nitride carbide SiNC, lithium fluoride LiF, tin (IV) SnO ₂ , or aluminum oxide (alumina) Al ₂ O. _The polarizing plate according to claim 6, which is ₃ .   The polarizing plate according to claim 1, wherein the sealing layer is composed of a single layer or a plurality of layers, and at least one layer thereof is a dense layer composed of parylene or an organic / inorganic hybrid material.   The polarizing plate according to claim 1, wherein the sealing material is made of an ultraviolet curable resin.   The polarizing plate according to claim 9, wherein the sealing material is made of an ultraviolet curable epoxy resin or acrylic resin.   The polarizing plate according to claim 1 or 2, wherein the polymer resin member is made of triacetyl cellulose resin, polyether sulfone resin, polycarbonate resin, cycloolefin polymer resin, polyethylene terephthalate resin, or polyethylene naphthalate resin.   The optical apparatus provided with the polarizing plate as described in any one of Claims 1-11 as a member which controls the light permeate | transmitted or radiate | emitted.   The optical device according to claim 12, which is configured as a liquid crystal display device.

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