JP2011022202A - Polarizing plate and image display device using the same - Google Patents

Abstract

A polarizing plate in which a transparent protective film is formed on one surface of a polarizer via an adhesive layer, and an adhesive layer is formed on the other surface of the polarizer, and maintains the quality of the polarizing plate. To provide a polarizing plate that can suppress the occurrence of color loss in a high-temperature and high-humidity environment and the rise of the end of the polarizing plate.
The present invention is a polarizing plate in which a transparent protective film is formed on one surface of a polarizer via an adhesive layer, and an adhesive layer is formed on the other surface of the polarizer, The polarizing plate is characterized in that the outer peripheral end face of the polarizing plate is covered with a sealing agent layer obtained by curing a sealing agent containing an ultraviolet curable resin or a thermosetting resin.
[Selection] Figure 1

Description

  The present invention relates to a polarizing plate used in an image display device such as a liquid crystal display device, and an image display device using the same.

  A polarizing plate is widely used as a polarized light supplying element and a polarized light detecting element in a liquid crystal display device. As the polarizing plate, a polarizing plate in which a transparent protective film is laminated on both sides is generally used. However, in recent years, liquid crystal display devices have been developed for mobile devices such as notebook personal computers and mobile phones. Is required to be thinner and lighter with the development of large-screen TVs. For this reason, various investigations have been made in which one transparent protective film is omitted and the transparent protective film is laminated only on one surface of the polarizer (see, for example, Patent Documents 1 and 2).

  On the other hand, in response to the strong market demand to further reduce the thickness and weight of liquid crystal display devices, the liquid crystal panels, diffusion plates, backlight units, and drive ICs that make up liquid crystal display devices are being made thinner and smaller. . Under such circumstances, the polarizing plate, which is a member constituting the liquid crystal panel, is also required to be thinned in units of 10 μm. However, when the polarizing plate is thinned and kept in a high-temperature and high-humidity environment, color penetration around the polarizing plate may occur due to the ingress of moisture from the cut end surface (outer peripheral end surface) of the polarizing plate, or in a high-temperature environment. When held, there is a problem that the end of the polarizing plate swells due to contraction of the polarizer.

  Patent Document 3 proposes that the outer peripheral end face of the polarizing plate is coated with a PVA (polyvinyl alcohol) -based resin. However, in PVA coating, since the PVA is hydrophilic and the thickness of the coating layer is thin, the end portion Insufficient water penetration and shrinkage prevention from the water, and insufficient to prevent color loss and edge bulges.

Japanese Patent Laid-Open No. 10-186133 JP 2007-193333 A JP 2006-195209 A

  The present invention is a polarizing plate in which a transparent protective film is formed on one surface of a polarizer via an adhesive layer, and an adhesive layer is formed on the other surface of the polarizer, and the quality of the polarizing plate is maintained. It is another object of the present invention to provide a polarizing plate that can suppress the occurrence of color loss under high-temperature and high-humidity environments and the occurrence of swelling at the end of the polarizing plate.

  That is, the present invention is a polarizing plate in which a transparent protective film is formed on one surface of a polarizer via an adhesive layer, and an adhesive layer is formed on the other surface of the polarizer. The polarizing plate is characterized in that the outer peripheral end face is covered with a sealant layer obtained by curing a sealant containing an ultraviolet curable resin or a thermosetting resin.

The thickness of the sealing agent layer is preferably 1 μm to 5 mm.
The moisture permeability after curing of the sealant is preferably 60 g / m ² · 24 hr or less in an environment of a temperature of 40 ° C. and a relative humidity of 90% at a thickness of 100 μm.

  Furthermore, it is preferable that the surface of the polarizing plate on the transparent protective film side is covered with the sealant layer.

  The polarizer is preferably one in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin film.

  An optical layer showing another optical function may be laminated on the surface of the transparent protective film opposite to the polarizer.

  The present invention also relates to an image display device using the polarizing plate.

  In the present invention, the outer peripheral end face of the polarizing plate is covered with a sealing agent layer cured with a sealing agent containing a hydrophobic ultraviolet curable resin or a thermosetting resin, so that moisture from the end of the polarizing plate under wet heat conditions can be obtained. Since the penetration and the shrinkage of the polarizer at a high temperature can be suppressed, the effect of simultaneously suppressing the color loss at the end and the swelling at the end can be obtained.

It is a schematic cross section which shows an example of the polarizing plate of this invention. It is a schematic cross section which shows another example of the polarizing plate of this invention. It is a schematic cross section which shows another example of the polarizing plate of this invention. It is a schematic cross section which shows another example of the polarizing plate of this invention.

  In the polarizing plate of the present invention, a transparent protective film is formed on one side of a polarizer having a dichroic dye adsorbed and oriented on a polyvinyl alcohol resin film via an adhesive layer, and an adhesive layer is formed on the other side of the polarizer. The outer peripheral end surface (cut end surface) of the polarizing plate is covered with a sealant layer.

  FIG. 1 is a schematic cross-sectional view showing an example of the polarizing plate of the present invention. A transparent protective film 3 is formed on one side of the polarizer 1 via an adhesive layer 2, and an adhesive layer 4 is formed on the opposite side of the transparent protective film 3, and an image is displayed outside the adhesive layer 4. A release film 7 is provided to temporarily protect the surface of the element until it is attached to an element or the like. A sealant layer 5 is formed on the cross section of the polarizing plate. In addition, in this invention, an outer peripheral end surface means the outer peripheral surface except the main surface (The outer surface of the transparent protective film 3 and the outer surface of the adhesive layer 4 in FIG. 1) of a polarizing plate.

  FIG. 2 is a schematic cross-sectional view showing another example of the polarizing plate of the present invention. In the example shown in FIG. 2, in addition to the configuration shown in FIG. 1, a retardation film 6 and another pressure-sensitive adhesive layer 4 are further provided on the pressure-sensitive adhesive layer 4 side of the polarizing plate.

  FIG. 3 is a schematic cross-sectional view showing still another example of the polarizing plate of the present invention. In the example shown in FIG. 2, not only the outer peripheral end surface but also the upper surface of the transparent protective film 3 is covered with the sealant layer 5. As described above, in the present invention, not only the outer peripheral end face of the polarizing plate but also the surface on the transparent protective film side is coated with the sealant layer, thereby enhancing the effect of preventing color loss at the end of the polarizing plate and suppressing swelling. It is done. In the present invention, the surface of the polarizing plate on the side of the transparent protective film means that the surface of the transparent protective film 3 or the surface of the transparent protective film is laminated with an optical layer exhibiting another optical function. It means the surface of the optical layer.

  FIG. 4 is a schematic cross-sectional view showing still another example of the polarizing plate of the present invention. In the example shown in FIG. 4, in addition to the configuration shown in FIG. 3, a retardation film 6 and another pressure-sensitive adhesive layer 4 are further provided on the pressure-sensitive adhesive layer 4 side of the polarizing plate.

<Polarizer>
As the polarizer, one obtained by subjecting a polyvinyl alcohol resin film to uniaxial stretching and dyeing treatment with a dichroic dye and adsorbing and orienting the dichroic dye is preferably used. The polyvinyl alcohol-based resin constituting the polarizer is usually obtained by saponifying a polyvinyl acetate-based resin. The degree of saponification of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 90 to 100 mol%, more preferably 99 to 100 mol%. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers, such as ethylene-vinyl acetate copolymers. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of polymerization of the polyvinyl alcohol-based resin is usually 1000 to 10000, preferably 1500 to 5000.

  These polyvinyl alcohol resins may be modified. For example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral and the like which are modified with aldehydes may be used. As a starting material for producing a polarizer, an unstretched film of a polyvinyl alcohol-based resin film having a thickness of usually 20 to 100 μm, preferably 30 to 80 μm is preferably used. Industrially, the practical width of the film is 1500 to 4000 mm. The unstretched film is processed in the order of swelling treatment, dyeing treatment, boric acid treatment and water washing treatment, subjected to uniaxial stretching in the steps up to boric acid treatment, and finally dried to obtain a thickness of the polarizer of usually 5 ~ 50 μm.

  There are roughly two methods for manufacturing a polarizer. In the first method, a polyvinyl alcohol-based resin film is uniaxially stretched in air or an inert gas, followed by solution treatment in the order of a swelling treatment step, a dyeing treatment step, a boric acid treatment step, and a water washing treatment step, and finally drying. How to do it. In the second method, an unstretched polyvinyl alcohol-based resin film is solution-treated with an aqueous solution in the order of a swelling treatment step, a dyeing treatment step, a boric acid treatment step and a water washing treatment step, and the boric acid treatment step and / or the previous step. In this method, uniaxial stretching is performed in a wet process, followed by drying.

  In any method, the uniaxial stretching may be performed in one step or in two or more steps, but is preferably performed in two or more steps. As a stretching method, a known method can be adopted. For example, stretching between rolls in which stretching is performed with a peripheral speed difference between two nip rolls that transport a film, hot roll stretching described in Japanese Patent No. 2731813, etc. Method and tenter stretching method. The order of the steps is basically as described above, but there are no restrictions on the number of treatment baths, treatment conditions, and the like. Moreover, you may add the process which is not described in the said 1st and 2nd method for another objective. Examples of such steps include immersion treatment with an aqueous iodide solution not containing boric acid (iodide treatment) or immersion treatment with an aqueous zinc solution containing zinc chloride not containing boric acid (zinc treatment) after boric acid treatment. ).

  The swelling treatment step is performed for the purpose of removing foreign matter on the film surface, removing the plasticizer in the film, imparting easy dyeability in the next step, and plasticizing the film. The processing conditions are determined within a range in which these objects can be achieved, and in a range in which problems such as extreme dissolution and devitrification of the base film do not occur. When a film previously stretched in a gas is swollen, the film is usually immersed in an aqueous solution at 20 to 70 ° C., preferably 30 to 60 ° C. The immersion time of the film is usually 30 to 300 seconds, preferably 60 to 240 seconds. When the unstretched raw film is swollen from the beginning, the film is usually immersed in an aqueous solution at 10 to 50 ° C., preferably 20 to 40 ° C. The immersion time of the film is usually 30 to 300 seconds, preferably 60 to 240 seconds.

  In the swelling treatment process, since the film is likely to swell in the width direction and wrinkles into the film, a known wide roll (expander roll), spiral roll, crown roll, cross guider, bend bar, tenter clip, etc. It is preferable to convey the film while removing the wrinkles of the film with a widening device. For the purpose of stabilizing film transport in the bath, the water flow in the swelling bath is controlled by an underwater shower, or EPC (Edge Position Control device: a device that detects the edge of the film and prevents meandering of the film) It is also useful to use them together. In this step, since the film swells and expands in the film transport direction, it is preferable to provide means for controlling the speed of the transport roll before and after the treatment tank, for example, in order to eliminate sagging of the film in the transport direction. In addition to pure water, the swelling treatment bath used is boric acid (described in JP-A-10-153709), chloride (described in JP-A-06-281816), inorganic acid, inorganic salt, water-soluble An aqueous solution to which an organic solvent, alcohol or the like is added in an amount of 0.01 to 0.1% by mass can also be used.

  The dyeing process with the dichroic dye is performed for the purpose of adsorbing and orienting the dichroic dye on the film. The processing conditions are determined within a range in which these objects can be achieved, and in a range in which problems such as extreme dissolution and devitrification of the base film do not occur. When iodine is used as the dichroic dye, it is usually 10 to 45 ° C., preferably 20 to 35 ° C. under a mass ratio of iodine / potassium iodide / water = 0.003 to 0.2 / 0.1. Using an aqueous solution having a concentration of 10/100, the immersion treatment is usually performed for 30 to 600 seconds, preferably 60 to 300 seconds. Instead of potassium iodide, other iodides such as zinc iodide may be used. Other iodides may be used in combination with potassium iodide. Furthermore, compounds other than iodide, such as boric acid, zinc chloride, and cobalt chloride, may coexist. When boric acid is added, it is distinguished from the following boric acid treatment in that it contains iodine. Any dye containing 0.003 parts by mass or more of iodine with respect to 100 parts by mass of water can be regarded as a dyeing tank.

  When a water-soluble dichroic dye is used as the dichroic dye, the dichroic dye / water is generally 0.001 to 0.1 / in mass ratio under the temperature condition of 20 to 80 ° C., preferably 30 to 70 ° C. Using an aqueous solution with a concentration of 100, an immersion treatment is usually performed for 30 to 600 seconds, preferably 60 to 300 seconds. The aqueous solution of the dichroic dye to be used may contain a dyeing assistant or the like, for example, may contain an inorganic salt such as sodium sulfate or a surfactant. The dichroic dye may be used alone, or two or more dichroic dyes may be used in combination.

  As described above, the film may be stretched in a dyeing tank. Stretching is performed by a method of giving a peripheral speed difference between the nip rolls before and after the dyeing tank. Similarly to the swelling treatment step, a widening roll (expander roll), a spiral roll, a crown roll, a cross guider, a bend bar and the like can be installed in the dyeing bath and / or at the bath entrance / exit.

  The boric acid treatment is performed by immersing a polyvinyl alcohol resin film dyed with a dichroic dye in an aqueous solution containing usually 1 to 10 parts by mass of boric acid with respect to 100 parts by mass of water. When the dichroic dye is iodine, it is preferable to contain 1 to 30 parts by mass of iodide. Examples of iodide include potassium iodide and zinc iodide. In addition, compounds other than iodide, such as zinc chloride, cobalt chloride, zirconium chloride, sodium thiosulfate, potassium sulfite, and sodium sulfate may coexist.

  The boric acid treatment is carried out for water resistance by crosslinking or hue adjustment (for example, to prevent bluish tint). When boric acid treatment is performed for water resistance by cross-linking, a cross-linking agent such as glyoxal or glutaraldehyde can be used in addition to boric acid or together with boric acid, if necessary. In addition, the boric acid treatment for water resistance may be referred to by names such as water resistance treatment, crosslinking treatment, and immobilization treatment. In addition, boric acid treatment for hue adjustment may be referred to by a name such as complementary color treatment or re-dyeing treatment.

  This boric acid treatment is performed by appropriately changing the concentrations of boric acid and iodide and the temperature of the treatment bath according to the purpose. The boric acid treatment for water resistance and the boric acid treatment for hue adjustment are not particularly distinguished, but can be carried out under the following conditions. When the raw film is subjected to swelling treatment, dyeing treatment, boric acid treatment, and boric acid treatment is aimed at water resistance by crosslinking, boric acid is usually added in an amount of 3 to 10 mass per 100 mass parts of water. A boric acid treatment bath containing 1 to 20 parts by mass of iodide is usually used, and the temperature is usually 50 to 70 ° C, preferably 55 to 65 ° C. The immersion time is usually 90 to 300 seconds. In addition, when performing the dyeing | staining process and a boric-acid process to the film extended | stretched previously, the temperature of a boric-acid processing bath is 50-85 degreeC normally, Preferably it is 55-80 degreeC.

  You may make it perform the boric-acid process for hue adjustment after the boric-acid process for water resistance. For example, when the dichroic dye is iodine, for this purpose, a boric acid treatment bath containing usually 1 to 5 parts by mass of boric acid and usually 3 to 30 parts by mass of iodide for 100 parts by mass of water is used. Used, usually at a temperature of 10 to 45 ° C. The immersion time is usually 3 to 300 seconds, preferably 10 to 240 seconds. The subsequent boric acid treatment for adjusting the hue is usually performed at a lower boric acid concentration, a higher iodide concentration, and a lower temperature than the boric acid treatment for water resistance.

  These boric acid treatments may consist of a plurality of steps and are usually carried out in 2 to 5 steps. In this case, the aqueous solution composition and temperature of each boric acid treatment tank to be used may be the same or different within the above-described range. The boric acid treatment for water resistance and the boric acid treatment for hue adjustment may be performed in a plurality of steps, respectively.

  In the boric acid treatment step, the film may be stretched as in the dyeing treatment step. The final cumulative draw ratio is usually 4 to 7 times, preferably 4.5 to 6.5 times. The cumulative stretching ratio here means how long the reference length in the length direction of the original film is in all the films after the completion of the stretching process. For example, it is 1 m in the original film. If the portion is 5 m in all the films after the stretching treatment, the cumulative stretching ratio at that time is 5 times.

  After the boric acid treatment, a water washing treatment is performed. The water washing treatment is performed by immersing a polyvinyl alcohol resin film treated with boric acid for water resistance and / or hue adjustment in water, spraying water as a shower, or using both immersion and spraying. The water temperature in the water washing treatment is usually 2 to 40 ° C., and the immersion time is usually 2 to 120 seconds.

  Here, in each step after the stretching treatment, tension control may be performed so that the tension of the film becomes substantially constant. Specifically, when stretching is completed in the dyeing process, tension control is performed in the subsequent boric acid treatment process and the water washing process. When stretching is completed in the previous process of the dyeing process, tension control is performed in subsequent processes including the dyeing process and the boric acid process. When the boric acid treatment step is composed of a plurality of boric acid treatment steps, the film is stretched in the boric acid treatment step from the first stage or the first to the second stage, and the next boric acid treatment step after the boric acid treatment step in which the stretching treatment is performed. Tension control is performed in each step from the acid treatment step to the water washing step, or the above-described film is stretched in the boric acid treatment step from the first to the third step, and the boric acid next to the boric acid treatment step in which the stretching treatment is performed. Although it is preferable to perform tension control in each step from the treatment step to the water washing step, industrially, the film was stretched in the boric acid treatment step from the first or the first to the second stage, and the stretching step was performed. It is more preferable to perform tension control in each step from the boric acid treatment step next to the boric acid treatment step to the water washing step. In addition, when performing the above-described iodide treatment or zinc treatment after boric acid treatment, tension control can be performed also in these steps.

  The tension in each step from the swelling treatment to the water washing treatment may be the same or different. The tension to the film in the tension control is not particularly limited, and is appropriately set within a range of usually 150 to 2000 N / m, preferably 600 to 1500 N / m per unit width. If the tension is too small, the film will be easily wrinkled. On the other hand, if the tension is too large, problems such as film breakage and shortened life due to bearing wear occur. The tension per unit width is calculated from the film width near the entrance of the process and the tension value of the tension detector. In addition, when tension control is performed, the film may be inevitably slightly stretched or shrunk, but this is not usually included in the stretching process.

  At the end of the polarizer manufacturing process, a drying process is performed. The drying treatment is preferably carried out in a large number of stages by changing the tension little by little, but is usually carried out in 2 to 3 stages due to equipment limitations. When performed in two stages, the tension in the front stage is preferably set in the range of 600 to 1500 N / m, and the tension in the rear stage is preferably set in the range of 300 to 1200 N / m. When the tension becomes too large, the film breaks more, and when it becomes too small, the generation of wrinkles increases, which is not preferable. Moreover, it is preferable to set the drying temperature of a front | former stage from the range of 30-90 degreeC, and the drying temperature of a back | latter stage from the range of 50-100 degreeC. If the temperature is too high, the film will be ruptured and the optical properties will be deteriorated. If the temperature is too low, streaks will increase, which is not preferable. The drying processing time can be, for example, 60 to 600 seconds, and the drying time in each stage may be the same or different. If the time is too long, it is not preferable in terms of productivity, and if the time is too short, drying is insufficient, which is not preferable.

  In this way, the polyvinyl alcohol resin film is subjected to uniaxial stretching, dyeing treatment with a dichroic dye, and boric acid treatment to obtain a polarizer. The thickness of this polarizer is usually 5 to 40 μm. Moreover, the moisture content of this polarizer becomes like this. Preferably it is 3-14 mass%, More preferably, it is 3-10 mass%, More preferably, it is 3-8 mass%. When the moisture content of the polarizer is too low, the polarizer becomes brittle, and it is easy to tear along the stretching direction, making it difficult to handle, and when the moisture content of the polarizer is too high, the polarizer is in a dry heat environment. There is a risk that it will tend to shrink below. The moisture content of the polarizer can be calculated from the mass change before and after being held at 105 ° C. under dry heat for 1 hour. A polarizer having a moisture content within the above-described preferred range can be obtained, for example, by controlling the drying temperature and drying time of the polarizer.

<Transparent protective film>
A transparent protective film is laminated on one surface of the polarizer via an adhesive layer to form a polarizing plate. As transparent protective film, cycloolefin resin film, cellulose acetate resin film such as triacetyl cellulose, diacetyl cellulose, polyester resin film such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, polycarbonate resin film, Examples thereof include films that have been widely used in the art, such as acrylic resin films and polypropylene resin films.

  Examples of the cycloolefin resin include commercially available products such as Topas (manufactured by Ticona), Arton (manufactured by JSR Corporation), ZEONOR (manufactured by ZEON Corporation), ZEONEX (ZEON Corporation, Japan). (Made by Co., Ltd.) and Apel (made by Mitsui Chemicals, Inc.) can be used suitably. When such a cycloolefin-based resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. Commercially available cycloolefin resin films such as ESCINA (manufactured by Sekisui Chemical Co., Ltd.), SCA40 (manufactured by Sekisui Chemical Co., Ltd.), Zeonoa Film (manufactured by Optes Co., Ltd.), etc. May be used.

  The cycloolefin resin film may be uniaxially stretched or biaxially stretched. By stretching, an arbitrary retardation value can be given to the cycloolefin-based resin film. Stretching is usually performed continuously while unwinding the film roll, and is stretched in the heating furnace in the roll traveling direction, the direction perpendicular to the traveling direction, or both. The temperature of the heating furnace is usually in the range from near the glass transition temperature of the cycloolefin resin to the glass transition temperature + 100 ° C. The draw ratio is usually 1.1 to 6 times, preferably 1.1 to 3.5 times.

  Since the cycloolefin resin film generally has poor surface activity, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment is performed on the surface to be bonded to the polarizer. preferable. Among these, plasma treatment and corona treatment that can be performed relatively easily are preferable.

  Examples of the cellulose acetate-based resin film include commercially available products such as Fujitac TD80 (Fuji Film Co., Ltd.), Fujitac TD80UF (Fuji Film Co., Ltd.), Fujitac TD80UZ (Fuji Film Co., Ltd.), and Fujitac TD40UZ. (Fuji Film Co., Ltd.), KC8UX2M (Konica Minolta Opto Co., Ltd.), KC4UY (Konica Minolta Opto Co., Ltd.) can be suitably used.

  The surface of the cellulose acetate-based resin film may be subjected to a surface treatment such as an antiglare treatment, a hard coat treatment, an antistatic treatment, or an antireflection treatment, depending on the application. Further, a liquid crystal layer or the like may be formed in order to improve the viewing angle characteristics. Moreover, in order to give a phase difference, you may extend | stretch a cellulose resin film. In addition, the cellulose acetate-based resin film is usually subjected to saponification treatment in order to improve the adhesion with the polarizer. As the saponification treatment, a method of immersing in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide can be employed.

  When the transparent protective film as described above is in a roll state, the films tend to adhere to each other and easily cause blocking. Therefore, the roll end part is subjected to uneven processing, a ribbon is inserted into the end part, or the protection is performed. A film is pasted or rolled.

  The transparent protective film is preferably thin, but if it is too thin, the strength is lowered and the processability is poor. On the other hand, when it is too thick, problems such as a decrease in transparency and a longer curing time after lamination occur. Therefore, the thickness of the transparent protective film is preferably 80 μm or less, more preferably 10 to 60 μm, and still more preferably 20 to 50 μm. In addition, since there is a demand for thinning including panels and modules from the market, since the polarizing plate is also required to be thin, the total thickness of the polarizer and the transparent protective film may be 100 μm or less. More preferably, it is 90 micrometers or less, More preferably, it is 80 micrometers or less.

<Bonding of polarizer and transparent protective film>
The polarizer and the transparent protective film are bonded via an aqueous adhesive layer using, for example, an aqueous polyvinyl alcohol resin solution, an aqueous two-component urethane emulsion adhesive, or the like.

  When a cellulose acetate film whose surface to be bonded to the polarizer is hydrophilized by a saponification process or the like is used as a transparent protective film, a polyvinyl alcohol resin aqueous solution is suitably used as an adhesive. Polyvinyl alcohol resins used as adhesives include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a homopolymer of vinyl acetate, as well as copolymers of vinyl acetate and other monomers. And vinyl alcohol copolymers obtained by saponification treatment, and modified polyvinyl alcohol polymers obtained by partially modifying hydroxyl groups thereof. A polyhydric aldehyde, a water-soluble epoxy compound, a melamine compound, a zirconia compound, a zinc compound, or the like may be added as an additive to the water-based adhesive. When such an aqueous adhesive is used, the adhesive layer obtained therefrom is usually 1 μm or less, and even when the cross section is observed with a normal optical microscope, the adhesive layer is practically not observed.

  The method of bonding the polarizer and the transparent protective film using the water-based adhesive is not particularly limited. For example, the adhesive is uniformly applied to the surface of the polarizer and / or the transparent protective film, and the coating surface is applied. The other film is stacked and bonded with a roll or the like and dried. Usually, an adhesive agent is apply | coated under the temperature of 15-40 degreeC after the preparation, and the bonding temperature is 15-30 degreeC normally.

  When using a water-system adhesive, after laminating | stacking a polarizer and a transparent protective film, in order to remove the water contained in a water-system adhesive, a laminated film (polarizing plate) is dried. Drying is performed by continuously passing through a drying furnace maintained at an appropriate temperature. Although such drying is not specifically limited, For example, it can carry out by winding the polarizing plate after drying in roll shape, making the inside of a drying furnace pass continuously.

  The temperature of the drying furnace is preferably 30 ° C to 60 ° C. When the transparent protective film is laminated only on one side of the polarizer, if the drying temperature is too high, bending due to the shrinkage of the polarizer tends to occur, and if the drying temperature is too low, the polarizer and the transparent protective film It becomes easy to peel between. The drying temperature is more preferably 40 to 60 ° C.

  The residence time of the laminated film in the drying furnace can be, for example, 10 to 1000 seconds, and particularly from the viewpoint of productivity, it is preferably 60 to 750 seconds, and more preferably 150 to 600 seconds.

  After drying, it may be further cured at room temperature or slightly higher temperature, for example, at 20 to 45 ° C. for about 12 to 600 hours. The temperature at the time of curing is generally set lower than the temperature adopted at the time of drying.

  Moreover, a photocurable adhesive can also be used as an adhesive at the time of bonding a polarizer and a transparent protective film. As a photocurable adhesive agent, the mixture of a photocurable epoxy resin and a photocationic polymerization initiator can be mentioned, for example.

  As a method of laminating a polarizer and a transparent protective film with a photocurable adhesive, a conventionally known method can be used, for example, casting method, Meyer bar coating method, gravure coating method, comma coater method, Examples thereof include a method of applying an adhesive to the adhesive surface of the polarizer and / or the transparent protective film and superimposing both by a doctor plate method, a die coating method, a dip coating method, and a spraying method. The casting method is a method of spreading and spreading an adhesive on the surface of a film to be coated while moving it in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two. Next, they are bonded together by being sandwiched by nip rolls. Moreover, after dripping an adhesive agent between a polarizer and a transparent protective film, the method of pressurizing this laminated body with a roll etc. and spreading it uniformly can also be used suitably. In this case, it is possible to use metal or rubber as the material of the roll. Furthermore, after dripping an adhesive agent between a polarizer and a transparent protective film, the method of passing this laminated body between rolls and pressurizing and spreading is also preferably employed. In this case, these rolls may be made of the same material or different materials.

  In addition, it is preferable that the thickness of the adhesive bond layer after bonding using the said nip roll etc. before drying or hardening is 5 micrometers or less, and it is preferable that it is 0.01 micrometers or more.

  In order to improve adhesion, the surface of the polarizer and / or the transparent protective film may be appropriately subjected to surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, saponification treatment or the like. Good. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

For curing, the photocurable adhesive is cured by irradiating active energy rays after bonding. The light source of the active energy ray is not particularly limited, but an active energy ray having a light emission distribution at a wavelength of 400 nm or less is preferable. Specifically, the low-pressure mercury lamp, the medium-pressure mercury lamp, the high-pressure mercury lamp, the ultrahigh-pressure mercury lamp, the chemical lamp, and the black light lamp A microwave excitation mercury lamp, a metal halide lamp and the like are preferably used. The light irradiation intensity to the photocurable adhesive is appropriately determined depending on the composition of the photocurable adhesive and is not particularly limited, but the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 0.1 to 6000 mW. / Cm ² is preferable. When the irradiation intensity is 0.1 mW / cm ² or more, the reaction time does not become too long, and when it is 6000 mW / cm ² or less, it is caused by heat radiated from the light source and heat generated during curing of the photocurable adhesive. There is little risk of yellowing of the epoxy resin and deterioration of the polarizer. The light irradiation time to the photocurable adhesive is controlled for each photocurable adhesive to be cured and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time is It is preferably set to be 10 to 10,000 mJ / cm ² . When the cumulative amount of light to the photocurable adhesive is 10 mJ / cm ² or more, a sufficient amount of active species derived from the polymerization initiator can be generated to allow the curing reaction to proceed more reliably, and at 10,000 mJ / cm ² or less. In some cases, irradiation time does not become too long and good productivity can be maintained. The thickness of the adhesive layer after irradiation with active energy rays is usually 0.001 μm or more, preferably 0.01 μm or more, and usually 5 μm or less, preferably 2 μm or less, more preferably 1 μm or less.

  When curing a photocurable adhesive by irradiation with active energy rays, curing can be performed under conditions that do not deteriorate the various functions of the polarizing plate, such as the degree of polarization of the polarizer, transmittance and hue, and transparency of the transparent protective film. preferable.

  When laminating a polarizer and a transparent protective film, the surface of the polarizer opposite to the surface on which the transparent protective film is pasted is used regardless of whether an aqueous adhesive or a photocurable adhesive is used. In order to protect from scratches or the like, a peelable protective film may be bonded to the surface of the polarizer. This protective film is peeled off as necessary, for example, when an adhesive layer is formed on the polarizer surface of the polarizing plate.

  The peeling force between the protective film and the polarizer is preferably 0.01 to 5 N / 25 mm, more preferably 0.01 to 2 N / 25 mm, and still more preferably 0.01 to 0.5 N / 25 mm. . When the peeling force is too small, the adhesion between the polarizer and the protective film is small, and the protective film may be partially peeled off. Also, if the peeling force is too large, it is difficult to peel the protective film from the polarizer, which is not preferable.

  As the material of the protective film, a polyethylene resin, a polypropylene resin, a polystyrene resin, a polyethylene terephthalate resin, etc., which are easy to handle and secure a certain degree of transparency, can be preferably used. A film obtained by molding two or more kinds into a single layer or a multilayer can be used as the transparent protective film.

  Examples of such protective films include “Sanitect” (trade name, sold by Sanei Kaken Co., Ltd.), polyethylene terephthalate resin, with an adhesive layer formed on the surface of the polyethylene resin film. "E-Mask" (trade name, manufactured by Nitto Denko Corporation) with an adhesive layer formed on the film surface, "Mastak" (trade name, Fujimori) with an adhesive layer formed on the polyethylene terephthalate resin film surface Kogyo Co., Ltd.).

  Among them, the self-adhesive protective film having adhesiveness to the polarizer by itself is simple because it is not necessary to protect the adhesive layer on the surface of the protective film, and can be used more suitably. . As a commercial item of the self-adhesive resin film which shows suitable peeling force with respect to the said polarizer, "Tretec" (brand name) which consists of a polyethylene resin by Toray Industries, Inc. can be mentioned, for example. The transparent protective film preferably has fewer defects such as fish eyes. If there is a defect, the shape may be transferred to the polarizer, resulting in a polarizer defect.

<Adhesive layer>
The polarizing plate thus obtained is laminated with a pressure-sensitive adhesive layer for bonding to other members such as a liquid crystal cell on the surface on the polarizer side.

  As the pressure-sensitive adhesive constituting the pressure-sensitive adhesive layer, a pressure-sensitive adhesive having an acrylic resin excellent in transparency, weather resistance, heat resistance and the like as a base polymer is suitable. The acrylic resin can be selected from known ones. For example, a homopolymer using one kind of alkyl (meth) acrylate such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, Copolymers using two or more of these alkyl (meth) acrylates, and also copolymers using one or more alkyl (meth) acrylates and one or more other monomers. Preferably used. Examples of other monomers copolymerizable with alkyl (meth) acrylate include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, hydroxyethyl (meth) acrylate, (meth) acrylamide, Polar monomers having a carboxy group, a hydroxyl group, an amide group, an amine group, an epoxy group, and the like such as N, N-dimethylaminoethyl (meth) acrylate and glycidyl (meth) acrylate are preferably used.

  The pressure-sensitive adhesive preferably contains a crosslinking agent. Crosslinking agents include divalent or higher metal ions that form carboxylic acid metal salts, compounds that contain amino groups that form amide bonds, compounds that contain epoxy groups, and hydroxyl groups. Examples of compounds that form an ester bond, compounds that contain an isocyanate group, that form an amide bond, and compounds that contain a carboxyl group that form an amide bond or an ester bond . In particular, compounds containing isocyanate groups are widely used as organic crosslinking agents.

  The pressure-sensitive adhesive may be an energy ray curable type or a thermosetting type. The energy ray curable pressure-sensitive adhesive has energy ray curable properties, has adhesiveness even before irradiation with energy rays, adheres to an adherend such as a film, and is cured by energy rays and has an adhesive force. It is a pressure-sensitive adhesive having properties that can be adjusted. As the energy ray curable adhesive, it is particularly preferable to use an ultraviolet curable adhesive. The energy beam curable pressure-sensitive adhesive generally comprises an acrylic resin and an energy beam polymerizable compound as main components. Furthermore, a photoinitiator, a crosslinking agent, and a photosensitizer can be blended as necessary.

  The thickness of the pressure-sensitive adhesive layer is preferably 1 to 40 μm, but it is desirable to apply it thinly within a range that does not impair the workability and durability characteristics, and keeps good workability and suppresses the dimensional change of the polarizer. Above, it is more preferably 3 to 25 μm. If the pressure-sensitive adhesive layer is too thin, the tackiness is lowered, and if it is too thick, problems such as the pressure-sensitive adhesive protruding easily occur.

<Other optical layers>
The polarizing plate of the present invention thus obtained may have another optical layer laminated on the transparent protective film side. Examples of other optical layers include a reflective polarizer that transmits certain types of polarized light and reflects polarized light that exhibits the opposite properties, a film with an antiglare function that has an uneven shape on the surface, and a surface antireflection function. Examples thereof include an attached film, a reflective film having a reflective function on the surface, and a transflective film having both a reflective function and a transmissive function. For example, DBEF (manufactured by 3M, available from Sumitomo 3M Co., Ltd. in Japan) is a commercially available product that corresponds to a reflective polarizer that transmits certain types of polarized light and reflects polarized light that exhibits opposite properties. APF (manufactured by 3M, available from Sumitomo 3M Co., Ltd. in Japan).

  The above-mentioned optical layer is usually laminated on the transparent protective film side of the polarizing plate via an adhesive layer. For this purpose, after the pressure-sensitive adhesive layer is previously formed on the transparent protective film of the polarizing plate, the optical layer may be bonded onto the pressure-sensitive adhesive layer, or after the pressure-sensitive adhesive layer is formed on the optical layer side. The optical layer may be bonded by adhering the pressure-sensitive adhesive layer to the transparent protective film surface of the polarizing plate.

  Further, an optical layer such as a hard coat layer, an antiglare layer, or an antireflection layer can be directly formed on the surface of the transparent protective film. The method for forming these optical layers on the surface of the transparent protective film is not particularly limited, and a known method can be used.

  In addition, lamination | stacking to the transparent protective film side of the polarizing plate of these optical layers may be performed before forming an adhesive layer on the opposite side to the transparent protective film of a polarizing plate, and the transparent protective film of a polarizing plate and You may carry out after forming an adhesive layer in the other side.

  In the polarizing plate of the present invention, another optical layer may be laminated on the pressure-sensitive adhesive layer side opposite to the transparent protective film. Examples of this optical layer include an optical compensation film coated with a liquid crystal compound on the surface of the substrate and oriented, a retardation film made of a polycarbonate-based resin, and a retardation film made of a cyclic polyolefin-based resin. Commercially available products corresponding to an optical compensation film coated with a liquid crystal compound on the substrate surface and oriented are WV film (Fuji Film Co., Ltd.), NH film (Shin Nippon Oil Co., Ltd.), NR Examples include films (manufactured by Nippon Oil Corporation). Commercial products corresponding to retardation films made of cyclic polyolefin resins include Arton Film (manufactured by JSR Corporation), Essina (manufactured by Sekisui Chemical Co., Ltd.), Zeonore Film (manufactured by Optes Corporation), etc. Is mentioned.

  The surface of these optical layers is usually provided with a pressure-sensitive adhesive layer for bonding to a member such as a liquid crystal cell, and a release film for protecting the pressure-sensitive adhesive surface of the pressure-sensitive adhesive layer is laminated. As the release film, a transparent resin film such as a polyethylene terephthalate film is preferably used.

  It does not specifically limit as an adhesive formed in the transparent protective film surface or the optical layer surface, According to the objective, a suitable thing can be selected from the well-known adhesives containing the previously illustrated adhesive. For example, in addition to those having a high storage elastic modulus as described above, those exhibiting a storage elastic modulus lower than that, for example, a pressure-sensitive adhesive having a storage elastic modulus of about 0.1 MPa or less used for a normal optical film, are not particularly limited. Can be used.

<Sealing agent layer>
In the present invention, the outer peripheral end face of the polarizing plate obtained above is covered with a sealant layer, and the sealant layer used below will be described.

  In the present invention, the sealant used for forming the sealant layer has fluidity at the time of processing, and has a sealing function after being processed, for example, an ultraviolet curable resin or a thermosetting resin, Or the resin etc. which harden | cure by both effect | actions can be illustrated. When using a resin having fluidity during processing, the viscosity of the resin before curing is 20 Pa · s or less, and preferably 0.01 Pa · s or more and 5 Pa · s or less. By using a material having a viscosity of 20 Pa · s or less, the time required for sealing is shortened due to its high fluidity. By using a material having a viscosity of 0.01 Pa · s or more, the sealing agent is transparent when sealing. It can be prevented from flowing out to the substrate or the outside.

  Moreover, 2 mass% or less is preferable, and, more preferably, the volatile component before hardening of a sealing agent is 1 mass% or less. When the volatile content is 2% by mass or less, the generation of microbubbles in the sealant layer after processing can be suppressed, and the sealant can be applied under reduced pressure, which can greatly improve the processing yield. It becomes possible. Here, the viscosity is a value measured according to JIS K 6249.

  A preferable glass transition temperature after curing of the sealant is 80 ° C. or more, more preferably about 120 to 200 ° C., and a preferable boiling absorption rate is 4% by mass or less, more preferably 2% by mass or less, and further preferably 1% by mass. % Or less. By using such a sealant, the heat resistance is improved, the intrusion of moisture from the atmosphere into the polarizer can be suppressed, and the moisture resistance of the obtained polarizing plate can be improved. Here, the boiling water absorption rate means the percentage of the mass increased after the cured product is immersed in boiling water for 1 hour with respect to the mass of the cured product before immersion, and is determined according to JIS K 6911.

  Specific examples of the sealant that satisfies the above viscosity condition and transmittance condition include polyolefin-based adhesives such as ethylene / anhydride copolymers (for example, BYNEL (registered trademark, DuPont)), epoxy resin-based adhesives ( For example, thermosetting epoxy resin EP 582 manufactured by Cemedine, UV curable epoxy resin KR695A manufactured by ADEKA, UV curable resin XNR5542 manufactured by Nagase ChemteX, urethane resin adhesive, phenol resin adhesive, etc. Adhesive, silicone resin (for example, UV-curable resin FX-V550, FX-V540, UV-curable silicone, silicone RTV, silicone rubber, modified silicone resin having a silyl group-terminated polyether), cyanoacrylate, acrylic resin UV curable adhesive such as There are exemplified.

  These sealants are preferably hydrophobic sealants, and more preferably silicone-based ultraviolet curable resins, thermosetting epoxy resins, ultraviolet curable epoxy resins, and ultraviolet curable acrylic resins. By using a hydrophobic sealant, the penetration of moisture from the end of the polarizing plate under wet heat conditions and the shrinkage of the polarizer at high temperatures can be suppressed, so that the end of the polarizing plate is discolored and swelled. The effect which suppresses is acquired.

The moisture permeability after curing of the sealant is preferably 60 g / m ² · 24 hr or less, more preferably 25 g / m ² · 24 hr or less at a temperature of 40 ° C. and a relative humidity of 90% in a thickness of 100 μm. . Thereby, the permeation | transmission of the water | moisture content from the air | atmosphere to a polarizer can be suppressed, and the moisture resistance of the polarizing plate obtained can be improved. The moisture permeability means the amount of moisture that passes through the cured product in 24 hours per 1 m ² of the cross-sectional area, and is determined according to JIS Z 0208.

  The thickness of the sealing agent layer can be appropriately adjusted depending on the type and size of the polarizing plate, but is 1 μm to 5 mm, and preferably 500 μm to 2 mm. If the thickness is less than 1 μm, it is not possible to suppress the ingress of moisture from the air into the polarizer in a humid heat environment, and it is not possible to suppress the rise of the end due to the contraction of the polarizer. When the thickness is more than 5 mm, there is a problem that the sealant layer is easily lost during handling.

  In this way, by using a sealant having a moisture permeability of a certain level or more, and by setting the thickness of the sealant layer to a certain level or more, moisture permeates from the end of the polarizing plate under wet heat conditions. In addition, since the shrinkage of the polarizer at high temperature can be further suppressed, the effect of suppressing color loss and swelling at the end of the polarizing plate is enhanced.

  In the present invention, either an ultraviolet curable resin or a thermosetting resin may be used. In particular, an ultraviolet curable resin is preferably used because it does not require a high temperature state in the curing step and does not deteriorate the optical performance of the polarizing plate.

<Preparation of sealant layer>
The method for coating the polarizing plate with the sealant layer is not particularly limited and can be performed by various methods. For example, it may be applied using a brush or the like, sprayed by a spray, an air brush, an ink jet method, or the like, or may be immersed in a solution of a sealant.

  The above treatment may be performed for each polarizing plate, or may be performed in a state where a plurality of sheets are laminated at a time. When a plurality of sheets are stacked, it is preferable to hold down firmly so that there is no gap in the laminate in order to prevent the sealant from entering through the gap between the laminates.

<Image display element>
The polarizing plate of this invention can be arrange | positioned at various image display elements, and can be set as an image display apparatus. For example, it can be arranged on one or both sides of a liquid crystal cell to form a liquid crystal display device. The liquid crystal cell used is arbitrary, for example, an active matrix drive type represented by VA (Vertical Allignment), IPS (In-plane Switching), ECB (Electrically Controlled Birefringence), OCB (Optically Compensated Birefringence) mode, etc. Liquid crystal display devices using various liquid crystal panels including simple matrix drive type represented by STN (Super Twisted Nematic) mode and static drive type represented by TN (Twisted Nematic) mode Can be formed. When providing the polarizing plate of this invention in the both sides of a liquid crystal cell, both may be the same and may differ. Regarding the formation of the liquid crystal display device, for example, appropriate components such as a diffusion plate, an antiglare layer, an antireflection film, a prism array, a lens array sheet, a light diffusion plate, and a backlight are arranged in one or more layers at appropriate positions. be able to.

  Furthermore, the polarizing plate of the present invention is also effectively used in a circularly polarized or elliptically polarized mode having an antireflection function in an image display device other than a liquid crystal display device, for example, a flat display such as an organic EL display device. Those skilled in the art will easily understand that when the image display element is an organic EL display element, the polarizing plate of the present invention may be bonded to one side thereof, that is, the viewing side display surface. Of course, the image display apparatus to which the polarizing plate of the present invention is applied is not limited to the one exemplified here.

  EXAMPLES Hereinafter, although an Example demonstrates this invention further in detail, this invention is not limited by these examples. In the examples, “%” and “part” representing the content or amount used are based on mass unless otherwise specified.

(Measurement of storage modulus of adhesive)
A cylindrical test piece having a thickness of 8 mmφ × 1 mm was prepared from the adhesive, and measured at a frequency of 1 Hz using DYNAMIC ANALYZER RDA II (manufactured by REOMETRIC).

(Measurement method of moisture permeability of sealant layer)
A film having a thickness of 10 μm was prepared from the sealant, and the cross-sectional area was 27 cm ^{2, which} was determined according to JIS Z 0208. This standard stipulates that the moisture permeability is measured at either 25 ° C. or 40 ° C., but in this specification, a temperature of 40 ° C. is adopted.

In the following examples, the following were used as the pressure-sensitive adhesive and sealant.
<Adhesive A>
A 38 μm-thick polyethylene terephthalate film (release film) having a release treatment applied to an organic solvent solution of an acrylic adhesive obtained by adding an isocyanate crosslinking agent to a copolymer of butyl acrylate and acrylic acid A sheet-like pressure-sensitive adhesive with a release film, which is coated on the release treatment surface so that the thickness after drying with a die coater is 15 μm. The storage elastic modulus of the pressure-sensitive adhesive at 23 ° C. is 0.85 MPa.

<Adhesive B>
A commercially available sheet-like pressure-sensitive adhesive in which an acrylic pressure-sensitive adhesive layer having a thickness of 25 μm is provided on a release-treated surface of a 38 μm-thick polyethylene terephthalate film (release film) that has been subjected to a release treatment. No urethane acrylate oligomer is blended. The storage elastic modulus of this pressure-sensitive adhesive layer was 0.05 MPa at 23 ° C.

<Sealant A>
Silicone-based ultraviolet curable resin (FX-V550 manufactured by ADEKA): moisture permeability 30 g / m ² · 24 hr.

<Sealant B>
Thermosetting epoxy resin (EP582 manufactured by Cemedine Co., Ltd .: moisture permeability 20 g / m ² · 24 hr).

Example 1
A transparent protective film made of a 40 μm thick triacetylcellulose film is made of an aqueous solution containing polyvinyl alcohol and a water-soluble epoxy resin on one side of a polarizer made of a 25 μm thick film in which iodine is adsorbed and oriented on polyvinyl alcohol. A polarizing plate bonded with an adhesive was prepared. Adhesive A was attached to the polyvinyl alcohol polarizer side to obtain a thin polarizing plate corresponding to FIG.

  Separately, an adhesive B is applied to one side of a retardation film ["Essina Film" manufactured by Sekisui Chemical Co., Ltd .: trade name] made of a norbornene resin having a thickness of 25 μm and an in-plane retardation of 140 nm. A retardation film with an adhesive was prepared. After peeling off the release film of the thin polarizing plate obtained above, the optical axis is the polarization of the polarizing plate on the side where the pressure-sensitive adhesive film is not provided on the pressure-sensitive adhesive layer side. A polarizing plate having the retardation film 6 shown in FIG. 2 is prepared by bonding so as to form an angle of 45 ° with respect to the absorption axis, and diagonally so that the polarization absorption axis is 30 degrees with respect to the long side. It was cut out at a size of 2.7 inches (about 6.9 cm).

After coating sealing agent A with a brush on the outer peripheral end face of the cut out polarizing plate, the sealing agent is cured by irradiating 1 J / cm ² of light with a high-pressure mercury lamp to obtain the polarizing plate of the present invention. It was. The thickness of the sealing agent layer was 2 mm.

(Example 2)
The polarizing plate of the present invention in which the outer peripheral end surface was coated with a sealing agent layer in the same manner as in Example 1 except that the sealing agent B was applied to the outer peripheral end surface of the polarizing plate with a brush and then heated and cured at 120 ° C. for 2 hours. Got. The thickness of the sealing agent layer was 500 μm.

(Comparative Example 1)
A polarizing plate was obtained in the same manner as in Example 1 except that it was not covered with the sealant layer and the outer peripheral end face was exposed.

(Evaluation)
The release films of the polarizing plates obtained in Examples 1 and 2 and Comparative Example 1 were peeled off, and the pressure-sensitive adhesive layer side was attached to a glass plate having a thickness of 0.7 mm, and the temperature was 50 ° C. and the pressure was 0.5 MPa for 20 minutes. Autoclaving was performed. The following evaluation was performed on each sample.

(Evaluation of color loss at the end of polarizing plate)
The sample was put into an oven maintained at a temperature of 60 ° C. and a relative humidity of 90% for 500 hours, and the color loss at the end of the polarizing plate was visually evaluated.

(Evaluation of rising edge of polarizing plate edge)
The sample was put into an oven maintained at a temperature of 85 ° C. for 500 hours, and the rising of the end of the polarizing plate was visually evaluated.

  The above evaluation results are summarized in Table 1.

  As shown in Table 1, in Comparative Example 1 in which the outer peripheral end surface was not covered with the sealant layer, color loss at the end of the polarizing plate and swell at the end of the polarizing plate were also observed. In Examples 1 and 2 coated with, no color loss at the end of the polarizing plate was observed, and the rise at the end of the polarizing plate was reduced as compared with Comparative Example 1. Therefore, by covering the outer peripheral end face of the polarizing plate with the sealant layer, it is possible to suppress color loss at the end and bulge of the end.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  DESCRIPTION OF SYMBOLS 1 Polarizer, 2 Adhesive layer, 3 Transparent protective film, 4 Adhesive layer, 5 Sealant layer, 6 Retardation film, 7 Release film.

Claims (7)

  A polarizing plate in which a transparent protective film is formed on one surface of a polarizer through an adhesive layer, and an adhesive layer is formed on the other surface of the polarizer, and the outer peripheral end surface of the polarizing plate is UV-cured. A polarizing plate, wherein a sealing agent containing a resin or a thermosetting resin is coated with a cured sealing agent layer.   The polarizing plate according to claim 1, wherein the sealant layer has a thickness of 1 μm to 5 mm. 3. The polarizing plate according to claim 1, wherein the moisture permeability of the encapsulant after curing is 60 g / m ² · 24 hr or less in an environment with a temperature of 40 ° C. and a relative humidity of 90% at a thickness of 100 μm.   Furthermore, the polarizing plate in any one of Claims 1-3 by which the surface by the side of the transparent protective film of the said polarizing plate was coat | covered with the said sealing agent layer.   The polarizing plate according to claim 1, wherein the polarizer is obtained by adsorbing and orienting a dichroic dye on a polyvinyl alcohol-based resin film.   The polarizing plate in any one of Claims 1-5 by which the optical layer which shows another optical function was laminated | stacked on the surface on the opposite side to the polarizer of the said transparent protective film.   The image display apparatus using the polarizing plate in any one of Claims 1-6.

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