JP4726145B2 - Adhesive for polarizing plate, polarizing plate, method for producing the same, optical film, and image display device - Google Patents

Description

  The present invention relates to an adhesive for polarizing plates. Moreover, this invention relates to the polarizing plate using the said adhesive agent for polarizing plates, and its manufacturing method. The polarizing plate can form an image display device such as a liquid crystal display device (LCD), an organic EL display device, a CRT, or a PDP alone or as an optical film in which the polarizing plate is laminated.

  Liquid crystal display devices are rapidly expanding in watches, mobile phones, PDAs, notebook computers, personal computer monitors, DVD players, TVs, and the like. The liquid crystal display device visualizes the polarization state by switching of the liquid crystal, and a polarizer is used from the display principle. In particular, in applications such as TVs, higher brightness, higher contrast, and wider viewing angles are required, and polarizing plates are also required to have higher transmittance, higher degree of polarization, and higher color reproducibility.

  As a polarizer, for example, an iodine-based polarizer having a stretched structure obtained by adsorbing iodine to polyvinyl alcohol has a high transmittance and a high degree of polarization, and is therefore widely used as the most common polarizer. In general, a polarizing plate is used in which a transparent protective film is bonded to both sides of a polarizer with a so-called aqueous adhesive in which a polyvinyl alcohol-based material is dissolved in water (Patent Document 1, Patent Document 2). . As the transparent protective film, triacetyl cellulose having a high moisture permeability is used.

  However, when a polarizing plate is manufactured as described above, when a water-based adhesive such as a polyvinyl alcohol-based adhesive is used, a drying step is required after the polarizer and the transparent protective film are bonded together. . The presence of a drying step in the production process of the polarizing plate is not preferable for improving the productivity of the polarizing plate.

  When using a water-based adhesive (so-called wet lamination), the moisture content of the polarizer must be relatively high in order to increase the adhesion to the adhesive (usually the moisture content of the polarizer is About 30%), a polarizing plate having good adhesion with an aqueous adhesive cannot be obtained. However, the polarizing plate thus obtained has problems such as large dimensional change at high temperatures and high temperatures and high humidity. On the other hand, in order to suppress the dimensional change, it is possible to reduce the moisture content of the polarizer or to use a transparent protective film having a low moisture permeability. However, when such a polarizer and a transparent protective film are bonded together using a water-based adhesive, a defect in appearance occurs and a practically useful polarizing plate cannot be obtained.

  In addition, as represented by TVs in particular, as the screen size of image display devices has increased in recent years, the increase in the size of polarizing plates has become very heavy from the standpoint of productivity and cost (yield and increased number of products). Yes. However, in the polarizing plate using the water-based adhesive described above, the so-called light leakage (unevenness) that the polarizing plate causes a dimensional change due to the heat of the backlight and becomes uneven and the black display appears white in a part of the entire screen. ) Becomes prominent.

  For the above reasons, it has been proposed to use a photoactive energy ray curable adhesive (in particular, an ultraviolet curable adhesive) instead of the water-based adhesive. However, none of the proposals considers the influence on the optical characteristics of the polarizing plate (for example, redness of the polarizing plate due to heating). Further, the process does not consider continuous winding from the viewpoint of productivity, which is very problematic.

  For example, an ultraviolet curable adhesive using an acrylic oligomer such as epoxy acrylate, urethane acrylate, or polyester acrylate as an adhesive and an acrylic or methacrylic monomer as a diluent has been proposed (Patent Document 3). However, the adhesive is subjected to a heat treatment (120 ° C. × 10 minutes) for completion of the reaction following the UV curing, and since the heat treatment takes time in particular, the current aqueous adhesive is used. It is almost the same as the case where it was, and there is a very problem in productivity.

  In addition, an ultraviolet curable adhesive using a mixture of urethane acrylate, epoxy acrylate, and polyester acrylate has been proposed (Patent Document 4). However, the adhesive is subjected to heat treatment (120 to 170 ° C., 10 to 100 minutes) after ultraviolet irradiation as in Patent Document 3, and the productivity is very poor. Further, damage (redness) to the polarizer due to heat treatment is not taken into consideration.

  In addition, it has been proposed to apply ultraviolet rays after applying an adhesive to a transparent protective film and then applying pressure (hot pressing, 90 ° C. × 15 minutes) or vacuum heating (Patent Documents 5 to 9). However, this pressurization and vacuum heating are difficult in the process, and there is no idea to wind up a polarizing plate with good productivity, and there is a problem in productivity. In addition, damage to the optical characteristics of the polarizer due to pressurization or vacuum heating is not considered at all.

  Moreover, after laminating a polarizer, an adhesive, and a transparent protective film, it has been proposed to perform hot pressing at 50 ° C. in a vacuum bag (Patent Document 10). However, this method, like the above, has a very poor productivity in the process of hot pressing, and in optical applications where a polarizing plate is used, there is a great risk that the occurrence of scratches will damage the commercial value and become fatal. . This method also has a problem that the heat curing time of the adhesive is as long as 2.5 to 30 minutes.

  Moreover, a polarizing filter using glass as a transparent substrate and using an ultraviolet curable adhesive as an adhesive is disclosed (Patent Document 11). However, the polarizing filter has a completely different form from the polarizing plate. Specifically, when glass is used as the transparent substrate, continuous winding is impossible (batch production), and productivity is poor. Further, since an ultraviolet curable adhesive is used, there is a problem that the curing of the adhesive becomes insufficient depending on the illuminance of ultraviolet rays, and the practical productivity does not increase.

  In addition, it is proposed to directly apply an ultraviolet curable or thermosetting epoxy adhesive (light or thermal cationic polymerization) on a polarizer (polyvinyl alcohol that has been dyed and stretched) (patent) Reference 12). However, with this method, there is a high possibility that unevenness occurs in the polarizer. In addition, productivity is poor due to a polymerization reaction by ultraviolet rays or a thermosetting adhesive.

  In addition, it has been proposed to use an amino-based resin having a triazine skeleton as an adhesive for polarizing plates (Patent Document 13). However, this method has poor productivity because the curing method is ultraviolet curing.

As described above, various ultraviolet curable adhesives have been proposed as adhesives for laminating the polarizer and the transparent protective film, but the productivity of the ultraviolet curable adhesives is not sufficient. In addition, depending on the type of material of the transparent protective film, sufficient adhesiveness cannot be satisfied depending on the ultraviolet curable adhesive.
JP 2006-220732 A JP 2001-296427 A JP 61-124719 A Japanese Patent No. 3731757 JP-A-8-216316 Japanese Patent No. 3511111 Japanese Patent No. 3511112 Japanese Patent No. 3511113 JP-A-8-216324 Special Table 2000-512035 JP 2002-131535 A JP 2004-245925 A JP 2004-70290 A

  An object of this invention is to provide the adhesive agent which can manufacture a polarizing plate with favorable adhesiveness with sufficient productivity with respect to a polarizer and a transparent protective film.

  Moreover, an object of this invention is to provide the polarizing plate using the said adhesive agent for polarizing plates, and its manufacturing method. Furthermore, an object of the present invention is to provide an optical film in which the polarizing plate is laminated, and to provide an image display device such as a liquid crystal display device using the polarizing plate and the optical film.

  As a result of intensive studies to solve the above problems, the present inventors have found that the object can be achieved by the following polarizing plate adhesive, and have completed the present invention.

That is, the present invention is an electron beam curable polarizing plate adhesive used for providing a transparent protective film on at least one side of a polarizer,
The said adhesive agent for polarizing plates is related with the adhesive agent for electron beam curing type polarizing plates characterized by containing the monofunctional (meth) acrylate which has an aromatic ring and a hydroxy group as a sclerosing | hardenable component.

  In the electron beam curable adhesive for polarizing plates, it is preferable that 50% by weight or more of a monofunctional (meth) acrylate having an aromatic ring and a hydroxy group is contained as a curable component.

  In the electron beam curable polarizing plate adhesive, the curable component preferably contains a bifunctional or higher (meth) acrylate in addition to the monofunctional (meth) acrylate.

  In the polarizing plate in which a transparent protective film is provided on at least one surface of a polarizer via an adhesive layer, the adhesive layer is formed of the electron beam curable polarizing plate adhesive. The present invention relates to a polarizing plate.

  In the polarizing plate, the polarizer is preferably a stretched polyvinyl alcohol film containing a dichroic substance.

  In the polarizing plate, as the transparent protective film, at least one selected from cellulose resin, polycarbonate resin, cyclic polyolefin resin, and (meth) acrylic resin is preferably used.

Further, the present invention is a method for producing the polarizing plate, wherein a transparent protective film is provided on at least one surface of a polarizer via an adhesive layer,
Applying the polarizing plate adhesive to the surface of the polarizer forming the adhesive layer and / or the surface of the transparent protective film forming the adhesive layer;
For the polarizer and the transparent protective film, the step of bonding the polarizer and the transparent protective film via the adhesive for the electron beam curable polarizing plate, and the polarizer and the transparent protective film bonded via the adhesive for the polarizing plate, Irradiating an electron beam to form an adhesive layer;
The present invention relates to a method for producing a polarizing plate, comprising:

  The present invention also relates to an optical film in which at least one polarizing plate is laminated.

  Furthermore, this invention relates to the image display apparatus characterized by using the said polarizing plate or the said optical film.

  In the present invention, an electron beam curable adhesive is used as the polarizing plate adhesive. That is, by using an electron beam as a method for curing the adhesive used for laminating the polarizer and the transparent protective film (that is, dry lamination), a heating step such as an ultraviolet curing method is not required, and productivity is greatly increased. Can be high.

  In the present invention, a monofunctional (meth) acrylate having an aromatic ring and a hydroxy group is selected and used as the curable component of the electron beam curable adhesive. The said sclerosing | hardenable component is suitable as an adhesive agent for electron beam curing type polarizing plates, and the polarizing plate which has favorable adhesiveness with respect to a polarizer and a transparent protective film is obtained by using the said adhesive agent. For example, even when a polarizer with a low moisture content is used, and when a material with low moisture permeability is used as the transparent protective film, the adhesive of the present invention exhibits good adhesion to them. As a result, a polarizing plate with good dimensional stability can be obtained.

  Thus, according to the present invention, since a polarizing plate with small dimensional change can be produced, it is possible to easily cope with an increase in the size of the polarizing plate, and it is possible to suppress the production cost from the viewpoint of yield and number of production. Further, since the polarizing plate obtained in the present invention has good dimensional stability, it is possible to suppress the occurrence of unevenness in the image display device due to the external heat of the backlight.

  The electron beam curable polarizing plate adhesive of the present invention contains a monofunctional (meth) acrylate having an aromatic ring and a hydroxy group as a curable component. (Meth) acrylate means acrylate and / or methacrylate. In the present invention, (meth) acrylate has this meaning.

  As the monofunctional (meth) acrylate having an aromatic ring and a hydroxy group, various monofunctional (meth) acrylates having an aromatic ring and a hydroxy group can be used. The hydroxy group may exist as a substituent of the aromatic ring, but in the present invention, it exists as an organic group (bonded to a hydrocarbon group, particularly an alkylene group) that bonds the aromatic ring and the (meth) acrylate. Those that do are preferred.

  Examples of the monofunctional (meth) acrylate having an aromatic ring and a hydroxy group include a reaction product of a monofunctional epoxy compound having an aromatic ring and (meth) acrylic acid. Examples of the monofunctional epoxy compound having an aromatic ring include phenyl glycidyl ether, t-butylphenyl glycidyl ether, and phenyl polyethylene glycol glycidyl ether. Specific examples of the monofunctional (meth) acrylate having an aromatic ring and a hydroxy group include, for example, 2-hydroxy-3-phenoxypropyl (meth) acrylate, 2-hydroxy-3-t-butylphenoxypropyl (meth) Examples thereof include acrylate and 2-hydroxy-3-phenyl polyethylene glycol propyl (meth) acrylate.

  The monofunctional (meth) acrylate having an aromatic ring and a hydroxy group contains 50% by weight or more as a curable component in the electron beam curable adhesive for polarizing plates, with respect to the polarizer and the transparent protective film. It is preferable for obtaining a polarizing plate having an adhesive layer with good adhesion. Furthermore, it is preferable from the viewpoint of coatability and processability. The ratio of the monofunctional (meth) acrylate having an aromatic ring and a hydroxy group is preferably 60% by weight or more, more preferably 70% by weight or more, and further preferably 80% by weight or more. preferable.

  In the present invention, a curable component other than a monofunctional (meth) acrylate having an aromatic ring and a hydroxy group (hereinafter, these are optional curable components) can be contained. Optional curable components include epoxy (meth) acrylates other than those exemplified above, various urethane (meth) acrylates, polyester (meth) acrylates, polyether (meth) acrylates, various (meth) acrylate monomers, vinyl System monomers. These optional monomers may or may not have an aromatic ring. Moreover, these arbitrary monomers may have a hydroxyl group and do not need to have it.

  The optional component may be monofunctional or bifunctional or higher, but it is preferable to use a bifunctional or higher functional component in terms of promoting a crosslinked structure and improving adhesiveness. As the bifunctional or higher optional component, a bifunctional or higher (meth) acrylate, particularly a bifunctional or higher epoxy (meth) acrylate is preferable from the above point. The bifunctional or higher functional epoxy (meth) acrylate is obtained by reacting a polyfunctional epoxy compound with (meth) acrylic acid. Various examples of the polyfunctional epoxy compound can be exemplified. Examples of the polyfunctional epoxy compound include aromatic epoxy resins, alicyclic epoxy resins, and aliphatic epoxy resins.

  Examples of the aromatic epoxy resin include bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, diglycidyl ether of bisphenol S; phenol novolac epoxy resin, cresol novolac epoxy resin, hydroxybenzaldehyde Examples thereof include novolak-type epoxy resins such as phenol novolac epoxy resins; glycidyl ethers of tetrahydroxyphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol.

  Examples of the alicyclic epoxy resins include hydrogenated products of the above-mentioned aromatic epoxy resins, cyclohexane-based, cyclohexylmethyl ester-based, cicyclohexylmethyl ether-based, spiro-based, and tricyclodecane-based epoxy resins.

  Examples of the aliphatic epoxy resin include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. Examples include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, propylene. Polyethers of polyether polyols obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as glycol diglycidyl ether, ethylene glycol, propylene glycol, and glycerin Examples thereof include glycidyl ether.

  The epoxy equivalent of the epoxy resin is usually in the range of 30 to 3000 g / equivalent, preferably 50 to 1500 g / equivalent.

  The bifunctional or higher epoxy (meth) acrylate is preferably an epoxy (meth) acrylate of an aliphatic epoxy resin, particularly preferably an epoxy (meth) acrylate of a bifunctional aliphatic epoxy resin.

  The electron beam curable polarizing plate adhesive of the present invention includes, as a curable component, a monofunctional (meth) acrylate having an aromatic ring and a hydroxy group, and an optional curable component. If necessary, additives may be added as appropriate. Examples of additives include sensitizers that increase the curing speed and sensitivity of electron beams typified by carbonyl compounds, adhesion promoters typified by silane coupling agents and ethylene oxide, and improved wettability with transparent protective films. Additives, acryloxy group compounds and hydrocarbons (natural and synthetic resins), additives that improve mechanical strength and processability, UV absorbers, anti-aging agents, dyes, processing aids, ions Examples include trapping agents, antioxidants, tackifiers, fillers, plasticizers, leveling agents, foam inhibitors, and antistatics.

  The polarizer is formed from a polyvinyl alcohol-based resin. The polarizer is a uniaxially stretched film obtained by dyeing a polyvinyl alcohol resin film with a dichroic substance (typically iodine or a dichroic dye). The polymerization degree of the polyvinyl alcohol resin constituting the polyvinyl alcohol resin film is preferably 100 to 5000, and more preferably 1400 to 4000. If the degree of polymerization is too low, the film tends to be stretched when performing predetermined stretching, and if the degree of polymerization is too high, tension may be abnormally required for stretching, and mechanical stretching may not be possible.

  The polyvinyl alcohol-based resin film constituting the polarizer can be formed by any appropriate method (for example, a casting method in which a solution obtained by dissolving a resin in water or an organic solvent is cast, a casting method, an extrusion method). Although the thickness of a polarizer is suitably set according to the objective and use of LCD with which a polarizing plate is used, it is about 5-80 micrometers normally.

  As a manufacturing method of the polarizer, any appropriate method is adopted depending on the purpose, material used, conditions and the like. For example, the system which uses the said polyvinyl alcohol-type resin film for a series of manufacturing processes including a swelling, dyeing | staining, bridge | crosslinking, extending | stretching, a water washing, and a drying process is employ | adopted normally. In each processing step except the drying step, the treatment is performed by immersing the polyvinyl alcohol-based resin film in a liquid containing a solution used in each step. The order, number of times, and presence / absence of each treatment of swelling, dyeing, crosslinking, stretching, washing and drying can be appropriately set according to the purpose, materials used and conditions. For example, several processes may be performed simultaneously in one step, and the swelling process, the dyeing process, and the crosslinking process may be performed simultaneously. Further, for example, it can be suitably employed to perform the crosslinking treatment before and after the stretching treatment. For example, the water washing process may be performed after all the processes, or may be performed only after a specific process.

  The swelling step is typically performed by immersing the polyvinyl alcohol resin film in a treatment bath filled with water. By this treatment, dirt on the surface of the polyvinyl alcohol-based resin film and an anti-blocking agent can be washed, and unevenness such as uneven dyeing can be prevented by swelling the polyvinyl alcohol-based resin film. Glycerin, potassium iodide or the like is appropriately added to the swelling bath. The temperature of the swelling bath is usually about 20 to 60 ° C., and the immersion time in the swelling bath is usually about 0.1 to 10 minutes.

  The dyeing process is typically performed by immersing the polyvinyl alcohol resin film in a treatment bath containing a dichroic substance such as iodine. As the solvent used for the dye bath solution, water is generally used, but an appropriate amount of an organic solvent compatible with water may be added. A dichroic substance is normally used in the ratio of 0.1-1 weight part with respect to 100 weight part of solvents. When iodine is used as the dichroic substance, the dye bath solution preferably further contains an auxiliary agent such as iodide. This is because the dyeing efficiency is improved. The auxiliary is preferably used in a proportion of 0.02 to 20 parts by weight, more preferably 2 to 10 parts by weight, with respect to 100 parts by weight of the solvent. Specific examples of iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Examples include titanium. The temperature of the dyeing bath is usually about 20 to 70 ° C., and the immersion time in the dyeing bath is usually about 1 to 20 minutes.

  The crosslinking step is typically performed by immersing the dyed polyvinyl alcohol-based resin film in a treatment desire containing a crosslinking agent. Arbitrary appropriate crosslinking agents are employ | adopted as a crosslinking rate. Specific examples of the crosslinking agent include boron compounds such as boric acid and borax, glyoxal, and glutaraldehyde. These may be used alone or in combination. As the solvent used for the solution of the crosslinking bath, water is generally used, but an appropriate amount of an organic solvent having compatibility with water may be added. A crosslinking agent is normally used in the ratio of 1-10 weight part with respect to 100 weight part of solvents. When the concentration of the crosslinking agent is less than 1 part by weight, sufficient optical properties cannot be obtained. When the concentration of the cross-linking agent exceeds 10 parts by weight, the stress generated in the film during stretching increases, and the resulting polarizing plate may shrink. It is desirable that the solution of the crosslinking bath further contains an auxiliary agent such as iodide. This is because it is easy to obtain uniform characteristics in the plane. The concentration of the auxiliary agent is preferably 0.05 to 15% by weight, more preferably 0.5 to 8% by weight. Specific examples of iodide are the same as those in the dyeing process. The temperature of the crosslinking bath is usually about 20 to 70 ° C, preferably 40 to 60 ° C. The immersion time in the crosslinking bath is usually about 1 second to 15 minutes, preferably 5 seconds to 10 minutes.

  The stretching process may be performed at any stage as described above. Specifically, it may be performed after the dyeing process, may be performed before the dyeing process, may be performed simultaneously with the swelling process, the dyeing process, and the crosslinking process, or may be performed after the crosslinking process. The cumulative draw ratio of the polyvinyl alcohol-based resin film is usually 5 times or more. Preferably it is 5 to 7 times, more preferably 5 to 6.5 times. When the cumulative draw ratio is less than 5 times, it is difficult to obtain a polarizing plate having a high degree of polarization. When the cumulative draw ratio exceeds 7 times, the polyvinyl alcohol-based resin film may be easily broken. Arbitrary appropriate methods are employ | adopted as a specific method of extending | stretching. For example, when a wet stretching method is employed, a polyvinyl alcohol resin film is stretched at a predetermined magnification in a treatment bath. As the stretching bath solution, a solution in which various metal salts, iodine, boron or zinc compounds are added to a solvent such as water or an organic solvent (for example, ethanol) is preferably used.

  The water washing step is typically performed by immersing the polyvinyl alcohol-based resin film subjected to the above-described various treatments in a treatment bath. The unnecessary residue of the polyvinyl alcohol-based resin film can be washed away by the water washing step. The washing bath may be pure water or an aqueous solution of iodide (for example, potassium iodide, sodium iodide, etc.). The concentration of the aqueous iodide solution is preferably 0.1 to 10% by weight. An auxiliary agent such as zinc sulfate or zinc chloride may be added to the aqueous iodide solution. The temperature of the washing bath is preferably 10 to 60 ° C, more preferably 30 to 40 ° C. The immersion time is 1 second to 1 minute. The washing step may be performed only once, or may be performed a plurality of times as necessary. When implemented several times, the kind and density | concentration of the additive contained in the washing bath used for each process are adjusted suitably. For example, the water washing step includes a step of immersing the polyvinyl alcohol resin film subjected to the above various treatments in an aqueous potassium iodide solution (0.1 to 10% by weight, 10 to 60 ° C.) for about 1 second to 1 minute, and pure water. Including rinsing process. In the water washing step, an organic solvent having compatibility with water (for example, ethanol) may be added as appropriate in order to improve the surface of the polarizer and increase the drying efficiency of the polarizer.

  Arbitrary appropriate methods (For example, natural drying, ventilation drying, heat drying) may be employ | adopted for a drying process. For example, the drying temperature in the case of heat drying is usually about 20 to 80 ° C., and the drying time is usually about 1 to 10 minutes. A polarizer is obtained as described above.

  The polarizer used in the present invention has a moisture content of preferably 15% by weight or less, more preferably 0 to 14% by weight, and still more preferably 1 to 14% by weight. When the moisture content is larger than 15% by weight, the dimensional change of the obtained polarizing plate becomes large, and there may be a problem that the dimensional change under high temperature or high temperature and high humidity becomes large.

  The moisture content of the polarizer of the present invention may be adjusted by any appropriate method. For example, there is a method of controlling by adjusting the conditions of the drying process in the manufacturing process of the polarizer.

  The moisture content of the polarizer is measured by the following method. That is, the polarizer was cut out to a size of 100 × 100 mm, and the initial weight of this sample was measured. Subsequently, this sample was dried at 120 ° C. for 2 hours, the dry weight was measured, and the moisture content was measured by the following formula. Moisture content (% by weight) = {(initial weight−dry weight) / initial weight} × 100. The weight was measured three times, and the average value was used.

  As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth) acrylic resins, cyclic Examples thereof include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. A transparent protective film is bonded to one side of the polarizer by an adhesive layer. On the other side, as a transparent protective film, (meth) acrylic, urethane-based, acrylurethane-based, epoxy-based, silicone A thermosetting resin such as a system or an ultraviolet curable resin can be used. One or more kinds of arbitrary appropriate additives may be contained in the transparent protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective film is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . When content of the said thermoplastic resin in a transparent protective film is 50 weight% or less, there exists a possibility that the high transparency etc. which a thermoplastic resin originally has cannot fully be expressed.

  Moreover, as a transparent protective film, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, (A) thermoplastic resin which has a substituted and / or unsubstituted imide group in a side chain, ( B) Resin compositions containing thermoplastic resins having substituted and / or unsubstituted phenyl and nitrile groups in the side chains. A specific example is a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. Since these films have a small phase difference and a small photoelastic coefficient, problems such as unevenness due to the distortion of the polarizing plate can be eliminated, and since the moisture permeability is small, the humidification durability is excellent.

  Although the thickness of a transparent protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. The transparent protective film is particularly suitable when the thickness is 5 to 150 μm.

  In addition, when providing a transparent protective film on both sides of a polarizer, the protective film which consists of the same polymer material may be used by the front and back, and the protective film which consists of a different polymer material etc. may be used.

  As the transparent protective film of the present invention, it is preferable to use at least one selected from cellulose resin, polycarbonate resin, cyclic polyolefin resin, and (meth) acrylic resin. The adhesive for electron beam curable polarizing plates of the present invention exhibits suitable adhesion to the various transparent protective films. In particular, the electron beam curable polarizing plate adhesive of the present invention exhibits good adhesion to acrylic resins that have been difficult to satisfy adhesiveness.

  Cellulose resin is an ester of cellulose and fatty acid. Specific examples of the cellulose ester resin include cellulose triacetate, cellulose diacetate, cellulose tripropionate, and cellulose dipropionate. Among these, cellulose triacetate is particularly preferable. Many products of cellulose triacetate are commercially available, which is advantageous in terms of availability and cost. Examples of commercially available cellulose triacetate are trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, “UZ” manufactured by Fuji Photo Film Co., Ltd. -TAC "and" KC series "manufactured by Konica. In general, these cellulose triacetates have an in-plane retardation (Re) of almost zero, but a thickness direction retardation (Rth) of about ˜60 nm.

  In addition, the cellulose resin film with a small thickness direction phase difference is obtained by processing the said cellulose resin, for example. For example, a base film such as polyethylene terephthalate, polypropylene, and stainless steel coated with a solvent such as cyclopentanone and methyl ethyl ketone is bonded to a general cellulose film and dried by heating (for example, at 80 to 150 ° C. for about 3 to 10 minutes). ) And then peeling the base film; a solution obtained by dissolving norbornene resin, (meth) acrylic resin, etc. in a solvent such as cyclopentanone, methyl ethyl ketone, etc. is applied to a general cellulose resin film and dried by heating ( For example, a method of peeling the coated film after 80 to 150 ° C. for about 3 to 10 minutes is mentioned.

  Moreover, as a cellulose resin film with a small thickness direction retardation, the fatty acid cellulose resin film which controlled the fat substitution degree can be used. Generally used triacetyl cellulose has an acetic acid substitution degree of about 2.8, but preferably the acetic acid substitution degree is controlled to 1.8 to 2.7, more preferably the propion substitution degree is controlled to 0.1 to 1. As a result, Rth can be reduced. Rth can be controlled to be small by adding a plasticizer such as dibutyl phthalate, p-toluenesulfonanilide, acetyltriethyl citrate to the fatty acid-substituted cellulose resin. The addition amount of the plasticizer is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight with respect to 100 parts by weight of the fatty acid cellulose resin.

  Specific examples of the cyclic polyolefin resin are preferably norbornene resins. The cyclic olefin-based resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And graft polymers obtained by modifying them with an unsaturated carboxylic acid or a derivative thereof, and hydrides thereof. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. Specific examples include the product names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, the product name “ARTON” manufactured by JSR Corporation, the product name “TOPAS” manufactured by TICONA, and the product rules manufactured by Mitsui Chemicals, Inc. “APEL”.

  The (meth) acrylic resin preferably has a Tg (glass transition temperature) of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. When Tg is 115 ° C. or higher, the polarizing plate can be excellent in durability. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability. From (meth) acrylic resin, a film having in-plane retardation (Re) and thickness direction retardation (Rth) of almost zero can be obtained.

  As the (meth) acrylic resin, any appropriate (meth) acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, poly (meth) acrylate C1-6 alkyl such as poly (meth) acrylate methyl is used. More preferred is a methyl methacrylate resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  Specific examples of (meth) acrylic resins include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. And a high Tg (meth) acrylic resin system obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure can also be used. It is because it has high mechanical strength by high heat resistance, high transparency, and biaxial stretching.

  Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in Japanese Patent No. 146084.

  The (meth) acrylic resin having a lactone ring structure preferably has a ring pseudo structure represented by the following general formula (Formula 1).

^Wherein, R 1, ^{R 2} and ^{R 3} each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The content ratio of the lactone ring structure represented by the general formula (Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is preferably 5 to 90% by weight, more preferably 10 to 70% by weight, More preferably, it is 10 to 60% by weight, and particularly preferably 10 to 50% by weight. When the content of the lactone ring structure represented by the general formula (Chemical Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is less than 5% by weight, the heat resistance, solvent resistance, and surface hardness are low. May be insufficient. If the content of the lactone ring structure represented by the general formula (Chemical Formula 1) in the structure of the (meth) acrylic resin having a lactone ring structure is more than 90% by weight, molding processability may be poor.

  The (meth) acrylic resin having a lactone ring structure has a mass average molecular weight (sometimes referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably. Is 50,000 to 500,000. If the mass average molecular weight is out of the above range, it is not preferable from the viewpoint of molding processability.

  The (meth) acrylic resin having a lactone ring structure preferably has a Tg of 115 ° C. or higher, more preferably 120 ° C. or higher, still more preferably 125 ° C. or higher, and particularly preferably 130 ° C. or higher. Since Tg is 115 ° C. or higher, for example, when incorporated into a polarizing plate as a transparent protective film, it has excellent durability. The upper limit of Tg of the (meth) acrylic resin having the lactone ring structure is not particularly limited, but is preferably 170 ° C. or less from the viewpoint of moldability and the like.

  The (meth) acrylic resin having a lactone ring structure is preferably as the total light transmittance of a molded product obtained by injection molding measured by a method according to ASTM-D-1003 is higher, preferably 85. % Or more, more preferably 88% or more, and still more preferably 90% or more. The total light transmittance is a measure of transparency. If the total light transmittance is less than 85%, the transparency may be lowered.

  As the transparent protective film, one having a front phase difference of less than 40 nm and a thickness direction retardation of less than 80 nm is usually used. The front phase difference Re is represented by Re = (nx−ny) × d. The thickness direction retardation Rth is represented by Rth = (nx−nz) × d. The Nz coefficient is represented by Nz = (nx−nz) / (nx−ny). [However, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction that maximizes the refractive index in the film plane. ]. In addition, it is preferable that a transparent protective film has as little color as possible. A protective film having a thickness direction retardation value of −90 nm to +75 nm is preferably used. By using a film having a thickness direction retardation value (Rth) of −90 nm to +75 nm, the coloring (optical coloring) of the polarizing plate caused by the transparent protective film can be almost eliminated. The thickness direction retardation value (Rth) is more preferably −80 nm to +60 nm, and particularly preferably −70 nm to +45 nm.

  On the other hand, as the transparent protective film, a phase difference plate having a phase difference with a front phase difference of 40 nm or more and / or a thickness direction retardation of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate functions also as a transparent protective film, so that the thickness can be reduced.

  Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or any of these binary, ternary copolymers, graft copolymers Examples thereof include polymers and blends. These polymer materials become an oriented product (stretched film) by stretching or the like.

  Examples of the liquid crystal polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. . Specific examples of the main chain type liquid crystal polymer include a nematic alignment polyester liquid crystal polymer, a discotic polymer, and a cholesteric polymer having a structure in which a mesogen group is bonded at a spacer portion that imparts flexibility. Specific examples of the side chain type liquid crystal polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment-providing para-substitution through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogenic part composed of a cyclic compound unit. These liquid crystal polymers are prepared by, for example, applying a solution of a liquid crystalline polymer on an alignment treatment surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate or an oblique deposition of silicon oxide. This is done by developing and heat treatment.

  The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for various wavelength plates or birefringence of liquid crystal layers and compensation of viewing angle, etc. It may be one in which retardation plates are stacked and optical characteristics such as retardation are controlled.

  The retardation plate has a relationship of nx = ny> nz, nx> ny> nz, nx> ny = nz, nx> nz> ny, nz = nx> ny, nz> nx> ny, nz> nx = ny. What is satisfactory is selected and used according to various applications. Note that ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

  For example, in a phase difference plate that satisfies nx> ny> nz, a surface plate having a front phase difference of 40 to 100 nm, a thickness direction phase difference of 100 to 320 nm, and an Nz coefficient of 1.8 to 4.5 is used. Is preferred. For example, in a retardation plate (positive A plate) that satisfies nx> ny = nz, it is preferable to use a retardation plate that satisfies a front phase difference of 100 to 200 nm. For example, for a retardation plate (negative A plate) that satisfies nz = nx> ny, it is preferable to use a retardation plate that satisfies a front phase difference of 100 to 200 nm. For example, in a phase difference plate that satisfies nx> nz> ny, it is preferable to use one that satisfies a front phase difference of 150 to 300 nm and an Nz coefficient of more than 0 to 0.7. Further, as described above, for example, nx = ny> nz, nz> nx> ny, or nz> nx = ny can be used.

  The transparent protective film can be appropriately selected according to the applied liquid crystal display device. For example, in the case of VA (including Vertical Alignment, MVA, and PVA), it is desirable that at least one of the polarizing plates (cell side) has a retardation. As specific phase differences, it is desirable that Re = 0 to 240 nm and Rth = 0 to 500 nm. In terms of the three-dimensional refractive index, nx> ny = nz, nx> ny> nz, nx> nz> ny, nx = ny> nz (uniaxial, biaxial, Z-ized, negative C-plate) is desirable. When polarizing plates are used above and below the liquid crystal cell, both the upper and lower sides of the liquid crystal cell may have a phase difference, or any one of the upper and lower transparent protective films may have a phase difference.

  For example, in the case of IPS (including In-Plane Switching, FFS), both cases where the transparent protective film on one side of the polarizing plate has a phase difference and does not have a phase difference can be used. For example, when there is no phase difference, it is desirable that the liquid crystal cell does not have a phase difference both above and below (cell side). When the liquid crystal cell has a phase difference, it is desirable that the liquid crystal cell has a phase difference on both the upper and lower sides. No phase difference, A-plate on the top, positive C-plate on the bottom). When it has a phase difference, it is desirable that Re = −500 to 500 nm and Rth = −500 to 500 nm. In terms of the three-dimensional refractive index, nx> ny = nz, nx> nz> ny, nz> nx = ny, nz> nx> ny (uniaxial, Z-ized, positive C-plate, positive A-plate) are desirable.

  In addition, the film which has the said phase difference can be separately bonded to the transparent protective film which does not have a phase difference, and the said function can be provided.

  The transparent protective film may be subjected to a surface modification treatment before coating with an adhesive. Specific examples of the treatment include corona treatment, plasma treatment, primer treatment, and saponification treatment.

  The surface of the transparent protective film to which the polarizer is not adhered may be subjected to a hard coat layer, an antireflection treatment, an antisticking treatment, or a treatment for diffusion or antiglare.

  The hard coat treatment is applied for the purpose of preventing scratches on the surface of the polarizing plate. For example, a transparent protective film with a cured film excellent in hardness, sliding properties, etc. by an appropriate ultraviolet curable resin such as acrylic or silicone is used. It can be formed by a method of adding to the surface of the film. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the polarizing plate, and can be achieved by forming an antireflection film or the like according to the conventional art. In addition, the sticking prevention treatment is performed for the purpose of preventing adhesion with an adjacent layer (for example, a backlight-side diffusion plate).

  The anti-glare treatment is applied for the purpose of preventing the outside light from being reflected on the surface of the polarizing plate and obstructing the visibility of the light transmitted through the polarizing plate. For example, the surface is roughened by a sandblasting method or an embossing method. It can be formed by imparting a fine concavo-convex structure to the surface of the transparent protective film by an appropriate method such as a blending method of transparent fine particles. Examples of the fine particles to be included in the formation of the surface fine concavo-convex structure include conductive materials made of silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide, and the like having an average particle diameter of 0.5 to 20 μm. In some cases, transparent fine particles such as inorganic fine particles, organic fine particles composed of a crosslinked or uncrosslinked polymer, and the like are used. When forming the surface fine uneven structure, the amount of fine particles used is generally about 2 to 70 parts by weight, preferably 5 to 50 parts by weight, based on 100 parts by weight of the transparent resin forming the surface fine uneven structure. The antiglare layer may also serve as a diffusion layer (viewing angle expanding function or the like) for diffusing the light transmitted through the polarizing plate to expand the viewing angle.

  The antireflection layer, antisticking layer, diffusion layer, antiglare layer, and the like can be provided on the transparent protective film itself, or can be provided separately from the transparent protective film as an optical layer.

  The polarizing plate of the present invention is produced by laminating a transparent protective film and a polarizer using the adhesive. In the production method, the adhesive is applied to the surface of the polarizer on which the adhesive layer is formed and / or the surface of the transparent protective film on which the adhesive layer is formed; the polarizer and the transparent protective film; Are bonded to each other through the polarizing plate adhesive; and the polarizer and the transparent protective film bonded through the polarizing plate adhesive are irradiated with an electron beam to form an adhesive layer. Forming.

  The adhesive coating method is appropriately selected depending on the viscosity of the adhesive and the target thickness. Examples of the coating method include a reverse coater, a gravure coater (direct, reverse or offset), a bar reverse coater, a roll coater, a die coater, a bar coater, a rod coater, and the like. In addition, for coating, a method such as a dapping method can be appropriately used.

  A polarizer and a transparent protective film are bonded together through the adhesive applied as described above. The polarizer and the transparent protective film can be bonded together using a roll laminator or the like.

  After bonding a polarizer and a transparent protective film, an electron beam is irradiated and an adhesive agent is hardened. The irradiation direction of the electron beam can be irradiated from any appropriate direction. Preferably, it irradiates from the transparent protective film side. When irradiated from the polarizer side, the polarizer may be deteriorated by the electron beam.

  Any appropriate condition can be adopted as the electron beam irradiation condition as long as the adhesive can be cured. For example, in the electron beam irradiation, the acceleration voltage is preferably 5 kV to 300 kV, and more preferably 10 kV to 250 kV. If the acceleration voltage is less than 5 kV, the electron beam may not reach the adhesive and may be insufficiently cured. If the acceleration voltage exceeds 300 kV, the penetration force through the sample is too strong and the electron beam rebounds, There is a risk of damaging the polarizer. The irradiation dose is 5 to 100 kGy, more preferably 10 to 75 kGy. When the irradiation dose is less than 5 kGy, the adhesive becomes insufficiently cured, and when it exceeds 100 kGy, the transparent protective film and the polarizer are damaged, resulting in a decrease in mechanical strength and yellowing, thereby obtaining predetermined optical characteristics. I can't.

  The thickness of the adhesive layer formed by the production method is preferably 0.1 to 20 μm, more preferably 0.2 to 10 μm, and still more preferably 0.3 to 8 μm. When the thickness is small, the cohesive force of the adhesive force itself cannot be obtained, and the adhesive strength may not be obtained. When the thickness of the adhesive layer exceeds 20 μm, the cost increases and the effect of curing shrinkage of the adhesive itself appears, which may adversely affect the optical properties of the polarizing plate.

  In the present invention, electron beam irradiation is usually performed in an inert gas, but if necessary, it may be performed in the atmosphere or under a condition in which oxygen is slightly introduced. Depending on the material of the transparent protective film, by appropriately introducing oxygen, the transparent protective film surface where the electron beam first hits can be obstructed to prevent oxygen damage and prevent damage to the transparent protective film. An electron beam can be irradiated efficiently.

  When performing the said manufacturing method by a continuous line, although it depends on the hardening time of an adhesive agent, Preferably it is 1-500 m / min, More preferably, it is 5-300 m / min, More preferably, it is 10-100 m / min. When the line speed is too low, productivity is poor, or damage to the transparent protective film is too great, and a polarizing plate that can withstand a durability test or the like cannot be produced. When the line speed is too high, the adhesive is not sufficiently cured, and the target adhesiveness may not be obtained.

  The polarizing plate of the present invention can be used as an optical film laminated with another optical layer in practical use. The optical layer is not particularly limited. For example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including wavelength plates such as 1/2 and 1/4), and a viewing angle compensation film. One or more optical layers that may be used can be used. In particular, a reflective polarizing plate or a semi-transmissive polarizing plate in which a polarizing plate or a semi-transmissive reflecting plate is further laminated on the polarizing plate of the present invention, an elliptical polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on the polarizing plate. A wide viewing angle polarizing plate obtained by further laminating a viewing angle compensation film on a plate or a polarizing plate, or a polarizing plate obtained by further laminating a brightness enhancement film on the polarizing plate is preferable.

  A reflective polarizing plate is a polarizing plate provided with a reflective layer, and is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side). Such a light source can be omitted, and the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as a method in which a reflective layer made of metal or the like is attached to one surface of the polarizing plate via a transparent protective layer or the like as necessary.

  Specific examples of the reflective polarizing plate include those in which a reflective layer is formed by attaching a foil or a vapor deposition film made of a reflective metal such as aluminum on one side of a transparent protective film matted as necessary. Moreover, the transparent protective film contains fine particles so as to have a surface fine concavo-convex structure and a reflective layer having a fine concavo-convex structure thereon. The reflective layer having the fine concavo-convex structure has an advantage that incident light is diffused by irregular reflection to prevent directivity and glaring appearance and to suppress unevenness in brightness and darkness. The transparent protective film containing fine particles also has an advantage that incident light and its reflected light are diffused when passing through it, and light and dark unevenness can be further suppressed. The reflective layer of the fine concavo-convex structure reflecting the surface fine concavo-convex structure of the transparent protective film is formed by transparent the metal by an appropriate method such as a vapor deposition method such as a vacuum vapor deposition method, an ion plating method, a sputtering method, or a plating method. It can be performed by a method of directly attaching to the surface of the protective layer.

  Instead of the method of directly applying the reflecting plate to the transparent protective film of the polarizing plate, the reflecting plate can be used as a reflecting sheet provided with a reflecting layer on an appropriate film according to the transparent film. Since the reflective layer is usually made of metal, the usage form in which the reflective surface is covered with a transparent protective film, a polarizing plate or the like is used to prevent the reflectance from being lowered due to oxidation, and thus to maintain the initial reflectance for a long time. In addition, it is more preferable to avoid a separate attachment of the protective layer.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side of a liquid crystal cell, and displays an image by reflecting incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device or the like that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate is useful for forming a liquid crystal display device of a type that can save energy of using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source even in a relatively dark atmosphere. It is.

  An elliptically polarizing plate or a circularly polarizing plate in which a retardation plate is further laminated on a polarizing plate will be described. A phase difference plate or the like is used when changing linearly polarized light to elliptically polarized light or circularly polarized light, changing elliptically polarized light or circularly polarized light to linearly polarized light, or changing the polarization direction of linearly polarized light. In particular, a so-called quarter-wave plate (also referred to as a λ / 4 plate) is used as a retardation plate that changes linearly polarized light into circularly polarized light or changes circularly polarized light into linearly polarized light. A half-wave plate (also referred to as a λ / 2 plate) is usually used when changing the polarization direction of linearly polarized light.

  The elliptically polarizing plate is effectively used for black and white display without the above color by compensating (preventing) the coloration (blue or yellow) generated by the birefringence of the liquid crystal layer of the super twist nematic (STN) type liquid crystal display device. It is done. Further, the one in which the three-dimensional refractive index is controlled is preferable because it can compensate (prevent) coloring that occurs when the screen of the liquid crystal display device is viewed from an oblique direction. The circularly polarizing plate is effectively used, for example, when adjusting the color tone of an image of a reflective liquid crystal display device in which an image is displayed in color, and also has an antireflection function. Specific examples of the retardation plate include a birefringent film obtained by stretching a film made of an appropriate polymer such as polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, polypropylene, other polyolefins, polyarylate, and polyamide. And an alignment film of a liquid crystal polymer, and a liquid crystal polymer alignment layer supported by a film. The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for various wavelength plates or birefringence of the liquid crystal layer, viewing angle, and the like. What laminated | stacked the phase difference plate and controlled optical characteristics, such as phase difference, etc. may be used.

  The elliptical polarizing plate and the reflective elliptical polarizing plate are obtained by laminating a polarizing plate or a reflective polarizing plate and a retardation plate in an appropriate combination. Such an elliptically polarizing plate or the like can also be formed by sequentially laminating them sequentially in the manufacturing process of the liquid crystal display device so as to be a combination of a (reflection type) polarizing plate and a retardation plate. An optical film such as a polarizing plate has an advantage that it can improve the production efficiency of a liquid crystal display device and the like because of excellent quality stability and lamination workability.

  The viewing angle compensation film is a film for widening the viewing angle so that an image can be seen relatively clearly even when the screen of the liquid crystal display device is viewed from a slightly oblique direction rather than perpendicular to the screen. As such a viewing angle compensation phase difference plate, for example, a retardation film, an alignment film such as a liquid crystal polymer, or an alignment layer such as a liquid crystal polymer supported on a transparent substrate is used. A normal retardation plate uses a birefringent polymer film uniaxially stretched in the plane direction, whereas a retardation plate used as a viewing angle compensation film stretches biaxially in the plane direction. Birefringent polymer film, biaxially stretched film such as polymer with birefringence with a controlled refractive index in the thickness direction that is uniaxially stretched in the plane direction and stretched in the thickness direction, etc. Used. Examples of the inclined alignment film include a film obtained by bonding a heat shrink film to a polymer film and stretching or / and shrinking the polymer film under the action of the contraction force by heating, and a film obtained by obliquely aligning a liquid crystal polymer. Can be mentioned. The raw material polymer for the phase difference plate is the same as the polymer described in the previous phase difference plate, preventing coloration due to a change in the viewing angle based on the phase difference by the liquid crystal cell and expanding the viewing angle for good visual recognition. An appropriate one for the purpose can be used.

  Also, from the viewpoint of achieving a wide viewing angle with good visibility, an optically compensated phase difference in which a liquid crystal polymer alignment layer, in particular an optically anisotropic layer composed of a discotic liquid crystal polymer gradient alignment layer, is supported by a triacetylcellulose film. A plate can be preferably used.

  A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is usually provided on the back side of a liquid crystal cell. The brightness enhancement film reflects a linearly polarized light with a predetermined polarization axis or a circularly polarized light in a predetermined direction when natural light is incident due to a backlight such as a liquid crystal display device or reflection from the back side, and transmits other light. In addition, a polarizing plate in which a brightness enhancement film is laminated with a polarizing plate allows light from a light source such as a backlight to enter to obtain transmitted light in a predetermined polarization state, and reflects light without transmitting the light other than the predetermined polarization state. The The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for liquid crystal display image display or the like by supplying polarized light that is difficult to be absorbed by the polarizer. That is, when light is incident through the polarizer from the back side of the liquid crystal cell without using a brightness enhancement film, light having a polarization direction that does not coincide with the polarization axis of the polarizer is almost polarized. It is absorbed by the polarizer and does not pass through the polarizer. That is, although depending on the characteristics of the polarizer used, approximately 50% of the light is absorbed by the polarizer, and the amount of light that can be used for liquid crystal image display or the like is reduced accordingly, resulting in a dark image. The brightness enhancement film allows light having a polarization direction that is absorbed by the polarizer to be reflected once by the brightness enhancement film without being incident on the polarizer, and further inverted through a reflective layer provided on the rear side thereof. Repeatedly re-enter the brightness enhancement film, and the brightness enhancement film transmits only polarized light whose polarization direction is such that the polarization direction of light reflected and inverted between the two can pass through the polarizer. Therefore, light such as a backlight can be efficiently used for displaying an image on the liquid crystal display device, and the screen can be brightened.

  A diffusion plate may be provided between the brightness enhancement film and the reflective layer. The polarized light reflected by the brightness enhancement film is directed to the reflective layer or the like, but the installed diffuser plate uniformly diffuses the light passing therethrough and simultaneously cancels the polarized state and becomes a non-polarized state. That is, the diffuser plate returns the polarized light to the original natural light state. The light in the non-polarized state, that is, the natural light state is directed toward the reflection layer and the like, reflected through the reflection layer and the like, and again passes through the diffusion plate and reenters the brightness enhancement film. Thus, while maintaining the brightness of the display screen by providing a diffuser plate that returns polarized light to the original natural light state between the brightness enhancement film and the reflective layer, etc., the brightness unevenness of the display screen is reduced at the same time, A uniform and bright screen can be provided. By providing such a diffuser plate, it is considered that the first incident light has a moderate increase in the number of repetitions of reflection, and in combination with the diffusion function of the diffuser plate, a uniform bright display screen can be provided.

  The brightness enhancement film has a characteristic of transmitting linearly polarized light having a predetermined polarization axis and reflecting other light, such as a multilayer thin film of dielectric material or a multilayer laminate of thin film films having different refractive index anisotropies. Such as an alignment film of a cholesteric liquid crystal polymer or an alignment liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light. Appropriate things, such as a thing, can be used.

  Therefore, in the brightness enhancement film of the type that transmits linearly polarized light having the predetermined polarization axis as described above, the transmitted light is incident on the polarizing plate with the polarization axis aligned as it is, thereby efficiently transmitting while suppressing absorption loss due to the polarizing plate. Can be made. On the other hand, in a brightness enhancement film of a type that transmits circularly polarized light such as a cholesteric liquid crystal layer, it can be directly incident on a polarizer, but from the point of suppressing absorption loss, the circularly polarized light is linearly polarized through a retardation plate. It is preferable to make it enter into a polarizing plate. Note that circularly polarized light can be converted to linearly polarized light by using a quarter wave plate as the retardation plate.

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

  In addition, the cholesteric liquid crystal layer can also be obtained by reflecting circularly polarized light in a wide wavelength range such as a visible light region by combining two or more layers having different reflection wavelengths and having an overlapping structure. Based on this, transmitted circularly polarized light in a wide wavelength range can be obtained.

  Further, the polarizing plate may be formed by laminating a polarizing plate and two or three or more optical layers like the above-described polarization separation type polarizing plate. Therefore, a reflective elliptical polarizing plate or a semi-transmissive elliptical polarizing plate in which the above-mentioned reflective polarizing plate or transflective polarizing plate and a retardation plate are combined may be used.

  An optical film in which the optical layer is laminated on a polarizing plate can be formed by a method of sequentially laminating separately in the manufacturing process of a liquid crystal display device or the like. There is an advantage that the manufacturing process of a liquid crystal display device or the like can be improved because of excellent stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. When adhering the polarizing plate and other optical films, their optical axes can be set at an appropriate arrangement angle in accordance with the target retardation characteristics.

  An adhesive layer for adhering to other members such as a liquid crystal cell may be provided on the polarizing plate described above or an optical film in which at least one polarizing plate is laminated. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and being excellent in weather resistance, heat resistance and the like can be preferably used.

  In addition to the above, in terms of prevention of foaming and peeling phenomena due to moisture absorption, deterioration of optical properties and liquid crystal cell warpage due to differences in thermal expansion, etc., as well as formability of liquid crystal display devices with high quality and excellent durability An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The adhesive layer is, for example, natural or synthetic resins, in particular, tackifier resins, fillers or pigments made of glass fibers, glass beads, metal powders, other inorganic powders, colorants, antioxidants, etc. It may contain an additive to be added to the adhesive layer. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  Attachment of the adhesive layer to one or both sides of the polarizing plate or the optical film can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method in which it is directly attached on a polarizing plate or an optical film by an appropriate development method such as a casting method or a coating method, or an adhesive layer is formed on a separator according to the above, and this is applied to a polarizing plate or an optical film. The method of moving up is mentioned.

  The pressure-sensitive adhesive layer can be provided on one side or both sides of a polarizing plate or an optical film as a superimposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as the adhesion layers of a different composition, a kind, thickness, etc. in the front and back of a polarizing plate or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive force, and is generally 1 to 40 μm, preferably 5 to 30 μm, particularly preferably 10 to 25 μm. If it is thinner than 1 μm, the durability will be poor, and if it is thicker than 40 μm, it will be liable to float or peel off due to foaming, resulting in poor appearance.

  On the exposed surface of the adhesive layer, a separator is temporarily attached and covered for the purpose of preventing contamination until it is put to practical use. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate conventional ones such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based, or molybdenum sulfide can be used.

  In order to improve the adhesion between the polarizing plate and the pressure-sensitive adhesive layer, an anchor layer can be provided between the layers.

  As the material for forming the anchor layer, an anchor agent selected from polyurethane, polyester, and polymers containing an amino group in the molecule is preferably used, and polymers containing an amino group in the molecule are particularly preferred. . Polymers containing an amino group in the molecule ensure good adhesion because the amino group in the molecule exhibits an interaction such as a reaction or ionic interaction with the carboxyl group in the pressure-sensitive adhesive.

  Examples of polymers containing an amino group in the molecule include polymers of amino-containing group-containing monomers such as polyethyleneimine, polyallylamine, polyvinylamine, polyvinylpyridine, polyvinylpyrrolidine, dimethylaminoethyl acrylate, and the like.

  An antistatic agent may be added to the anchor layer in order to impart antistatic properties. Antistatic agents for imparting antistatic properties include ionic surfactant systems, conductive polymer systems such as polyaniline, polythiophene, polypyrrole, and polyquinoxaline, metal oxide systems such as tin oxide, antimony oxide, and indium oxide. In particular, from the viewpoint of optical properties, appearance, antistatic effect, and antistatic effect heating and stability during humidification, a conductive polymer system is preferably used. Among these, water-soluble conductive polymers such as polyaniline and polythiophene or water-dispersible conductive polymers are particularly preferably used. When a water-soluble conductive polymer or a water-dispersible conductive polymer is used as a material for forming the antistatic layer, it is possible to suppress deterioration of the optical film substrate due to an organic solvent during coating.

  In the present invention, the polarizer, the transparent protective film, the optical film, and the like that form the polarizing plate described above, and each layer such as the adhesive layer include, for example, salicylic acid ester compounds, benzophenol compounds, benzotriazole compounds, and cyanoacrylates. It may be a compound having an ultraviolet absorbing ability by a method such as a method of treating with an ultraviolet absorber such as a compound based on nickel or a nickel complex salt compound.

  The polarizing plate or the optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing plate or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the polarizing plate or optical film by invention, and it can apply according to the former. As the liquid crystal cell, any type such as a TN type, STN type, π type, VA type, IPS type, or the like can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflector used in an illumination system can be formed. In that case, the polarizing plate or optical film by this invention can be installed in the one side or both sides of a liquid crystal cell. When providing a polarizing plate or an optical film on both sides, they may be the same or different. Further, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  Next, an organic electroluminescence device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light emitting layer and an electron injection layer composed of a perylene derivative or the like, or a laminate of these hole injection layer, light emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the phosphor material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  Examples of the present invention will be described below, but the embodiments of the present invention are not limited thereto.

(Polarizer)
A polyvinyl alcohol film having a thickness of 80 μm was dyed in an iodine solution of 5% by weight (weight ratio: iodine / potassium iodide = 1/10) at 30 ° C. for 0.5 minutes. Then, it is immersed in an aqueous solution containing 3% by weight boric acid and 2% by weight 30 ° C. potassium iodide for 0.5 minutes, and further 60 ° C. containing 4% by weight boric acid and 3% by weight potassium iodide. The film was stretched up to 6 times while immersed in an aqueous solution of 1 minute, and then immersed in a 5 wt% potassium iodide aqueous solution at 30 ° C. for 0.5 minutes. Then, it dried for 1 minute in 40 degreeC oven, and obtained the 30-micrometer-thick polarizer. The moisture content of the polarizer was 14% by weight.

(Polarizing plate with a transparent protective film on one side)
One side of the obtained polarizer was coated with an aqueous polyvinyl alcohol solution (3.5% by weight of polyvinyl alcohol, 25 parts by weight of methylol melamine added to 100 parts by weight of polyvinyl alcohol as a crosslinking ratio), and a triacetyl cellulose film was applied thereto. (Konica product name: KC4YYW, thickness 40 μm, Re = 1 nm, Rth = 40 nm) was attached and dried to obtain a polarizing plate having a transparent protective film (triacetylcellulose film: TAC) on one side. The thickness of the adhesive layer was 100 nm. A polarizing plate having TAC on one side (hereinafter referred to as a single TAC polarizing plate) was used in the following example.

(Phase difference value)
The phase difference value was measured using a phase difference meter based on the parallel Nicol rotation method (product name “KOBRA21-ADH” manufactured by Oji Scientific Instruments Co., Ltd.), nx, ny. , Nz, and film thickness (d), front phase difference Re, thickness direction phase difference Rth, and Nz were determined. [However, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction that maximizes the refractive index in the film plane. ]

Example 1
(Electron beam curable adhesive)
Only 2-hydroxy-3-phenoxypropyl acrylate (manufactured by Nagase ChemteX Corporation, DA-141) was used.

(Transparent protective film)
A lactonized polymethylmethacrylate film (LMMA, lactonization rate 20%, thickness 30 μm, Re = 0 nm, Rth = 0 nm) was used.

(Creation of polarizing plate)
The adhesive was applied to the transparent protective film so as to have a thickness of 5 μm, and then the polarizer side of the piece TAC polarizing plate was bonded thereto. Polarized light having a transparent protective film of TAC film on one side of the polarizer and a transparent protective film of LMMA film on the other side using an electron beam irradiation device EC110 manufactured by Iwasaki Electric Co., Ltd. I got a plate. The line speed was 5 m / min, the acceleration voltage was 110 kV, and the irradiation dose was 50 kGy.

Example 2
In Example 1, a film having a thickness of 50 μm obtained by subjecting a norbornene-based resin film (Arton, manufactured by JSR Corporation, thickness 150 μm) as a transparent protective film to a three-fold treatment at 150 ° C. by fixed-end lateral stretching. A polarizing plate was obtained in the same manner as in Example 1 except that (Re = 120 nm, Rth = 160 nm) was used.

Example 3
In Example 1, a film having a thickness of 50 μm obtained by subjecting a norbornene-based resin film (Arton, manufactured by JSR Corporation, thickness 150 μm) as a transparent protective film to a three-fold treatment at 150 ° C. by fixed-end lateral stretching. A polarizing plate was obtained in the same manner as in Example 1 except that a material subjected to corona treatment (line speed 8 m / min, output 2 kW) was used for (Re = 120 nm, Rth = 160 nm).

Example 4
In Example 1, as a transparent protective film, a norbornene-based resin film (Zeonor, manufactured by Nippon Zeon Co., Ltd., thickness 70 μm, laterally stretched, Re = 55 nm, Rth = 130 nm) was subjected to corona treatment (line speed 8 m / min, A polarizing plate was obtained in the same manner as in Example 1 except that one having an output of 2 kW) was used.

Example 5
In Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that an acrylic film (HTX, manufactured by Kaneka Corporation, thickness 40 μm, Re = 0 nm, Rth = 0 nm) was used as the transparent protective film. .

Example 6
In Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that a polycarbonate film (thickness 80 μm, Re = 140 nm, Rth = 140 nm) was used as the transparent protective film.

Example 7
In Example 1, as an adhesive, 99% by weight of 2-hydroxy-3-phenoxypropyl acrylate, bifunctional epoxy acrylate (manufactured by Nagase ChemteX Corporation, DA-920, diacrylate of polypropylene glycol diglycidyl ether) 1% A polarizing plate was obtained in the same manner as in Example 1 except that a mixture comprising% was used.

Example 8
In Example 1, as an adhesive, 95% by weight of 2-hydroxy-3-phenoxypropyl acrylate, bifunctional epoxy acrylate (manufactured by Nagase ChemteX Corporation, DA-920, diacrylate of polypropylene glycol diglycidyl ether) 5% A polarizing plate was obtained in the same manner as in Example 1 except that a mixture comprising% was used.

Example 9
In Example 1, as an adhesive, 90% by weight of 2-hydroxy-3-phenoxypropyl acrylate, bifunctional epoxy acrylate (manufactured by Nagase ChemteX Corporation, DA-920, diacrylate of polypropylene glycol diglycidyl ether) 10% A polarizing plate was obtained in the same manner as in Example 1 except that a mixture comprising% was used.

Example 10
In Example 1, as an adhesive, 85% by weight of 2-hydroxy-3-phenoxypropyl acrylate, bifunctional epoxy acrylate (manufactured by Nagase ChemteX Corporation, DA-920, diacrylate of polypropylene glycol diglycidyl ether) 15% A polarizing plate was obtained in the same manner as in Example 1 except that a mixture comprising% was used.

Comparative Example 1
In Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., UV-7600B) was used as the adhesive.

Comparative Example 2
In Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., UV-7461TE) was used as the adhesive.

Comparative Example 3
In Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that dicyclopentenyl acrylate (manufactured by Hitachi Chemical Co., Ltd., FA-511AS) was used as the adhesive.

Comparative Example 4
In Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that dicyclopentenyloxyethyl acrylate (manufactured by Hitachi Chemical Co., Ltd., FA-512AS) was used as the adhesive.

Comparative Example 5
In Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that dicyclopentenyloxyethyl acrylate (manufactured by Hitachi Chemical Co., Ltd., FA-513AS) was used as the adhesive.

Comparative Example 6
In Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that a photocurable epoxy resin (manufactured by Adeka Corporation, DL-100) was used as the adhesive.

Comparative Example 7
In Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that a photocurable epoxy resin (manufactured by Adeka Corporation, DL-200) was used as the adhesive.

Comparative Example 8
In Example 1, a polarizing plate was obtained in the same manner as in Example 1 except that a photocurable epoxy resin (Daiichi Seika Kogyo Co., Ltd., EB-AD-4) was used as the adhesive.

Comparative Example 9
In Example 1, as the adhesive, only a bifunctional epoxy acrylate (manufactured by Nagase ChemteX Corporation, DA-920, diacrylate of polypropylene glycol diglycidyl ether) was used. I got a plate.

Comparative Example 10
In Example 1, a polarizing plate was obtained in the same manner as Example 1 except that only phenoxy acrylate was used as the adhesive.

[Evaluation]
The following evaluation was performed about the polarizing plate (henceforth a polarizing plate with a both-sides transparent protective film) which has a transparent protective film on both sides obtained by the Example and the comparative example. The results are shown in Table 1.

<Initial adhesion>
The adhesive layer formed by the electron beam irradiation of the polarizing plate with the transparent protective film on both sides is put into a trigger, and the transparent layer bonded with the piece TAC polarizing plate and the adhesive layer formed by the electron beam irradiation in each of the above examples. The initial adhesion of whether or not the protective film was peeled off by hand was evaluated according to the following criteria. ○: Peeled off. X: Not peeled off. The sample peeled off with this initial adhesion does not have any adhesive force, and is not worthy of evaluating other items, and other items are not evaluated.

<Durability>
About the sample which was not peeled off by initial adhesion, after performing a reliability test of humidification (60 ° C./90% RH × 240 hours) and heating (80 ° C. × 240 hours), peeling was caused by the same evaluation as initial adhesion. The following criteria evaluated whether it produced. ○: Peeled off. X: Not peeled off.

<180 degree peel strength>
A sample (15 mm width) that was not peeled off in the initial adhesion evaluation was evaluated by a 180 degree peel test in order to quantify the adhesion. The transparent protective film (attached with an adhesive layer formed by electron beam irradiation) bonded in each example of the polarizing plates with transparent protective films on both sides was attached to the Nitto Denko Corporation No. It was affixed on the glass plate with 500 double-sided tape. A piece TAC polarizing plate was held by a chuck, a tensile test was performed at an angle of 180 degrees at a speed of 375 mm / min, and the peel strength at that time was measured. The strength obtained by averaging the stroke amount (pulling length) between 100 mm and 200 mm was defined as peel strength. In Table 1, the base material breakage is when the adhesive layer formed by electron beam irradiation has high adhesiveness, and the transparent protective film bonded in each example broke.

In the table, * 1: 2-hydroxy-3-phenoxypropyl acrylate,
* 2: Bifunctional epoxy acrylate (manufactured by Nagase ChemteX Corporation, DA-920, diacrylate of polypropylene glycol diglycidyl ether),
* 3: Urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., UV-7600B),
* 4: Urethane acrylate (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., UV-7461TE),
* 5: Dicyclopentenyl acrylate (manufactured by Hitachi Chemical Co., Ltd., FA-511AS),
* 6: Dicyclopentenyloxyethyl acrylate (manufactured by Hitachi Chemical Co., Ltd., FA-512AS),
* 7: Dicyclopentenyloxyethyl acrylate (manufactured by Hitachi Chemical Co., Ltd., FA-513AS),
* 8: Photocurable epoxy resin (manufactured by Adeka Corporation, DL-100),
* 9: Photocurable epoxy resin (manufactured by Adeka Corporation, DL-200),
* 10: Photo-curable epoxy resin (Daiichi Seika Kogyo Co., Ltd., EB-AD-4),
* 11: Phenoxy acrylate,
LMMA: Lactonized polymethyl methacrylate.

Claims (8)

An adhesive for an electron beam curable polarizing plate used for providing a transparent protective film on at least one side of a polarizer,
The adhesive for polarizing plates contains 80 to 100% by weight of a monofunctional (meth) acrylate having an aromatic ring and a hydroxy group as a curable component. The bifunctional or higher-functional (meth) acrylate is contained as the curable component, and the electron beam curable polarizing plate adhesive according to claim 1 . A polarizing plate in which a transparent protective film is provided on at least one surface of a polarizer via an adhesive layer, and the adhesive layer is formed by the electron beam curable polarizing plate adhesive according to claim 1 or 2. A polarizing plate characterized by being made. 4. The polarizing plate according to claim 3 , wherein the polarizer is a stretched polyvinyl alcohol-based film containing a dichroic substance. The polarizing plate according to claim 3 or 4 , wherein the transparent protective film is at least one selected from a cellulose resin, a polycarbonate resin, a cyclic polyolefin resin, and a (meth) acrylic resin. A method for producing a polarizing plate according to any one of claims 3 to 5 , wherein a transparent protective film is provided on at least one surface of the polarizer via an adhesive layer,
A step of applying the adhesive for an electron beam curable polarizing plate according to claim 1 or 2 to a surface of the polarizer that forms the adhesive layer and / or a surface of the transparent protective film that forms the adhesive layer;
A process of bonding a polarizer and a transparent protective film through the polarizing plate adhesive, and irradiating an electron beam to the polarizer and the transparent protective film bonded through the polarizing plate adhesive And forming an adhesive layer,
The manufacturing method of the polarizing plate characterized by having. 6. An optical film, wherein at least one polarizing plate according to claim 3 is laminated. An image display device, wherein a used optical film of the polarizing plate or claim 7, wherein according to any one of claims 3-5.