JP6706399B1 - Image display device - Google Patents

Abstract

A front transparent member, a polarizing film, and an image display cell are image display devices provided in this order via a pressure-sensitive adhesive layer or an adhesive layer, wherein the polarizing film has a polyvinyl alcohol-based film in which iodine is adsorbed and oriented. At least one of the polarizing film, the pressure-sensitive adhesive layer, and the adhesive layer contains a compound having a nitroxy radical or a nitroxide group, and the polarizing film has a general formula: (1): X (% by weight)>0.01 (in the general formula (1), X is both sides of a polarizing film in which a transparent protective film is attached to at least one surface of the polarizing film via the adhesive layer. In addition, a laminated body obtained by laminating glass plates via the pressure-sensitive adhesive layer contains a compound having a nitroxyl radical or a nitroxide group in the polarizing film in the laminated body left to stand at 105° C. for 24 hours. It shows the quantity.) The image display device has an excellent effect of suppressing a decrease in single transmittance due to coloring of the polarizing film in a high temperature environment.

Description

The present invention relates to an image display device.

Conventionally, as a polarizing film used for various image display devices such as liquid crystal display devices and organic EL display devices, since it has both high transmittance and high polarization degree, it has been dyed (such as iodine and dichroic dyes). Polyvinyl alcohol-based films (containing dichroic substances) have been used. The polarizing film is produced by subjecting a polyvinyl alcohol-based film to various treatments such as swelling, dyeing, crosslinking and stretching in a bath, followed by washing treatment and drying. The polarizing film is usually used as a polarizing film (polarizing plate) in which a protective film such as triacetyl cellulose is attached to one surface or both surfaces thereof with an adhesive.

The polarizing film is used as a laminated polarizing film (optical laminated body) by laminating other optical layers as necessary, and the polarizing film or the laminated polarizing film (optical laminated body) is a liquid crystal cell or an organic EL element. And the like, and the front side transparent member (window layer) on the viewing side and the front side transparent member such as a touch panel, which are bonded together via an adhesive layer or an adhesive layer to provide the above various image display devices. Used.

In recent years, such various image display devices have been widely used, such as being used as in-vehicle image display devices such as car navigation devices and back monitors in addition to mobile devices such as mobile phones and tablet terminals. There is. Along with this, the polarizing film and the laminated polarizing film are required to have higher durability in a more severe environment (for example, in a high temperature environment) than conventionally required, and such durability is required. A polarizing film for the purpose of ensuring the same has been proposed (Patent Document 1).

In addition, a dye-based polarizing film using a dichroic dye such as an azo-based compound generally has a higher temperature and a higher temperature than an iodine-based polarizing film (a polarizing film formed by adsorbing and orienting iodine on a polyvinyl alcohol-based film). It is known that light resistance under high humidity conditions is excellent (Patent Document 2), and in order to improve color loss in a light resistance test of a polarizing plate having the dye-based polarizing film, the polarizing plate is used. It is disclosed that the hindered amine compound is contained in the adhesive used (Patent Document 3).

Special table 2012-516468 gazette JP, 2001-240762, A JP, 2005-338343, A

On the other hand, as described above, a polarizing film or a laminated polarizing film using an iodine-based polarizing film that is said to be inferior in light resistance under high temperature and high humidity conditions than a dye-based polarizing film, when exposed to a high temperature environment. In addition, there is a problem in that the polarizing film is colored and the single transmittance thereof is lowered. In particular, an image display device constituted by laminating the above polarizing film or laminated polarizing film with an adhesive layer or an adhesive layer between the image display cell and the front transparent member is used for coloring the polarizing film. However, there is a problem in that the single substance transmittance is significantly reduced.

In view of the circumstances as described above, it is an object of the present invention to provide an image display device that is excellent in the effect of suppressing a decrease in single-piece transmittance due to coloring of a polarizing film in a high temperature environment.

That is, the present invention is an image display device in which a front transparent member, a polarizing film, and an image display cell are provided in this order via an adhesive layer or an adhesive layer, wherein the polarizing film is a polyvinyl alcohol film. At least one of the polarizing film, the pressure-sensitive adhesive layer, and the adhesive layer contains a compound having a nitroxy radical or a nitroxide group, The polarizing film has a general formula (1): X (% by weight)>0.01 (in the general formula (1), X is a transparent protective film attached to at least one surface of the polarizing film via the adhesive layer. A laminated body in which glass plates are bonded to both surfaces of the polarizing film via the pressure-sensitive adhesive layer is a nitroxy radical or a nitroxide in the polarizing film in the laminated body which is left under the condition of 105° C. for 24 hours. The content of the compound having a group is shown).

The details of the mechanism of action of the effect in the image display device of the present invention are unclear, but it is presumed as follows. However, the present invention may not be construed as being limited to this mechanism of action.

In the image display device of the present invention, the front transparent member, the polarizing film, and the image display cell are provided in this order via a pressure-sensitive adhesive layer or an adhesive layer, and the polarizing film, the pressure-sensitive adhesive layer, and the adhesive layer. At least one of the agent layers contains a compound having a nitroxy radical or a nitroxide group. Further, the polarizing film has an iodine-based polarizing film formed by adsorbing and orienting iodine on a polyvinyl alcohol-based film. As described in Patent Documents 2 and 3 above, it is generally said that the iodine-based polarizing film is inferior in durability such as heat resistance to the dye-based polarizing film, and the reason is included in the polarizing film. It is presumed that the iodine generated promotes the deterioration phenomenon called polyene formation that occurs in the dehydration reaction of polyvinyl alcohol in a high temperature environment.

On the other hand, the compound having a nitroxy radical or a nitroxide group contained in at least one of the polarizing film, the pressure-sensitive adhesive layer, and the adhesive layer of the present invention, when exposed to a high temperature environment, an image display device. A part of the nitroxy radical or the compound having a nitroxide group is transferred because it moves (stays) inside the image display device together with the water present inside (water present in the adhesive layer, adhesive layer, etc.). It is presumed that it penetrates into the iodine-based polarizing film. As a result, it is presumed that the nitroxy radical in the polarizing film or the compound having a nitroxide group can efficiently trap the radical generated in the above polyene reaction under a high temperature environment. In addition, it is possible to suppress a decrease in the single transmittance due to the coloring of the polarizing film.

It is a typical sectional view showing one form of an image display device. It is a typical sectional view showing one form of a single-sided protective polarizing film. It is a typical sectional view showing one form of a double-sided protective polarizing film.

FIG. 1 is a schematic cross-sectional view showing one form of the image display device of the present invention. In the image display device 100 of FIG. 1, the front transparent member 80 and the polarizing film 10 are attached to each other via the adhesive layer or the adhesive layer 20, and the image display cell 90 and the polarizing film 10 are attached to the adhesive layer or the adhesive layer. It is bonded via the agent layer 30.

FIG. 2 is a schematic cross-sectional view showing one mode of the single-sided protective polarizing film of the present invention. The single-sided protective polarizing film 101 of FIG. 2 shows one embodiment of the polarizing film 10 in which the polarizing film 11 and the transparent protective film 13 are bonded together via the pressure-sensitive adhesive layer or the adhesive layer 50.

FIG. 3 is a schematic cross-sectional view showing one form of the double-sided protective polarizing film of the present invention. In the double-sided protective polarizing film 102 shown in FIG. 3, the polarizing film 11 and the transparent protective film 13 are exposed to each other via the adhesive layer or the adhesive layer 50, and the polarizing film 11 and the transparent protective film 12 are adhesive. One mode of the polarizing film 10 bonded together via a layer or an adhesive layer 40 is shown.

In the image display device of the present invention, the front transparent member, the polarizing film, and the image display cell are provided in this order via a pressure-sensitive adhesive layer or an adhesive layer, and the polarizing film, the pressure-sensitive adhesive layer, and the adhesive layer. At least one of the agent layers contains a compound having a nitroxy radical or a nitroxide group. The compounds having a nitroxy radical or a nitroxide group may be used alone or in combination of two or more kinds.

（一般式（１）中、Ｒ^１は、オキシラジカル表し、Ｒ^２からＲ^５は、独立して、水素原子、または炭素原子数が１〜１０のアルキル基を表し、ｎは０または１を表す。）なお、一般式（１）中の、点線部の左は任意の有機基を示す。Examples of the compound having a nitroxyl radical or a nitroxide group, at room temperature, from the viewpoint of having a relatively stable radical in air, as N- oxyl compound (functional group, the C-N (-C) -O ^· compounds having (O ^· is an oxy radical)) can be mentioned, known materials can be used. Examples of the N-oxyl compound include compounds having an organic group having the following structure.

(In the general formula (1), R ¹ represents an oxy radical, R ² to R ⁵ independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n represents 0 or 1. In addition, in the general formula (1), the left side of the dotted line portion represents an arbitrary organic group.

（一般式（２）中、Ｒ^１からＲ^５、およびｎは、上記と同様であり、Ｒ^６は水素原子、または炭素原子数が１〜１０のアルキル基、アシル基、もしくはアリール基を表し、ｎは０または１を表す。）

（一般式（３）中、Ｒ^１からＲ^５、およびｎは、上記と同様であり、Ｒ^７およびＲ^８は、独立して、水素原子、または炭素原子数が１〜１０のアルキル基、アシル基、もしくはアリール基を表す。）

（一般式（４）中、Ｒ^１からＲ^５、およびｎは、上記と同様であり、Ｒ^９からＲ^１１は、独立して、水素原子、または炭素原子数が１〜１０のアルキル基、アシル基、アミノ基、アルコキシ基、ヒドロキシ基、もしくはアリール基を表す。）

（一般式（５）中、Ｒ^１からＲ^５、およびｎは、上記と同様であり、Ｒ^１２は、水素原子、または炭素原子数が１〜１０のアルキル基、アミノ基、アルコキシ基、ヒドロキシ基、もしくはアリール基を表す。）Examples of the compound having an organic group include compounds represented by the following general formulas (2) to (5).

(In the general formula (2), R ¹ to R ⁵ and n are the same as above, and R ⁶ represents a hydrogen atom or an alkyl group, an acyl group, or an aryl group having 1 to 10 carbon atoms. , N represents 0 or 1.)

(In the general formula (3), R ¹ to R ⁵ and n are the same as above, and R ⁷ and R ⁸ are independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, Represents an acyl group or an aryl group.)

(In the general formula (4), R ¹ to R ⁵ and n are the same as above, and R ⁹ to R ¹¹ are independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, Represents an acyl group, an amino group, an alkoxy group, a hydroxy group, or an aryl group.)

(In the general formula (5), R ¹ to R ⁵ and n are the same as above, and R ¹² is a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, an amino group, an alkoxy group, a hydroxy group. Represents a group or an aryl group.)

In the general formulas (1) to (5), R ² to R ⁵ are preferably an alkyl group having 1 to 6 carbon atoms and having 1 to 3 carbon atoms from the viewpoint of easy availability. More preferably, it is an alkyl group. Further, in the general formula (2), from the viewpoint of easy availability, R ⁶ is preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and more preferably a hydrogen atom. Further, in the general formula (3), from the viewpoint of easy availability, it is preferable that R ⁷ and R ⁸ are independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and a hydrogen atom. Is more preferable. Further, in the general formula (4), from the viewpoint of easy availability, R ⁹ to R ¹¹ are preferably hydrogen atoms or alkyl groups having 1 to 10 carbon atoms. In addition, in the general formula (5), R ¹² is preferably a hydroxy group, an amino group, or an alkoxy group from the viewpoint of easy availability. In the general formulas (1) to (5), n is preferably 1 from the viewpoint of easy availability.

As the N-oxyl compound, for example, N- described in JP-A-2003-64022, JP-A-11-222462, JP-A-2002-284737, International Publication No. 2016/047655 and the like. An oxyl compound is mentioned.

（一般式（６）中、Ｒは、水素原子、または炭素原子数が１〜１０のアルキル基、アシル基、もしくはアリール基を表す。）

Examples of the compound having a nitroxy radical or a nitroxide group include the following compounds.

(In the general formula (6), R represents a hydrogen atom or an alkyl group, an acyl group, or an aryl group having 1 to 10 carbon atoms.)

In addition, the compound having a nitroxy radical or a nitroxide group has a molecular weight of preferably 1,000 or less, more preferably 500 or less, from the viewpoint of efficiently trapping a radical generated in a polyene reaction. It is more preferably 300 or less.

<Polarizing film>
The polarizing film of the present invention has a polarizing film formed by adsorbing and orienting iodine on a polyvinyl alcohol film.

As the polyvinyl alcohol (PVA) film, a film having a light-transmitting property in a visible light region and capable of dispersing and adsorbing iodine can be used without particular limitation. In addition, the PVA-based film, which is usually used as a raw fabric, preferably has a thickness of about 1 to 100 μm, more preferably about 1 to 50 μm, and a width of about 100 to 5000 mm.

Examples of the material of the polyvinyl alcohol-based film include polyvinyl alcohol and derivatives thereof. Examples of the polyvinyl alcohol derivative include polyvinyl formal, polyvinyl acetal, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and their modified alkyl esters, acrylamides, and the like. Is mentioned. The average degree of polymerization of the polyvinyl alcohol is preferably about 100 to 10,000, more preferably about 1,000 to 10,000, and even more preferably about 1,500 to 4,500. .. The saponification degree of the polyvinyl alcohol is preferably about 80 to 100 mol %, more preferably about 95 mol% to 99.95 mol. The average degree of polymerization and the degree of saponification can be determined according to JIS K 6726.

The polyvinyl alcohol film may contain additives such as a plasticizer and a surfactant. Examples of the plasticizer include polyols such as glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol, and condensates thereof. The amount of the additive used is not particularly limited, but is preferably about 20% by weight or less in the polyvinyl alcohol film.

The content of the iodine in the polarizing film is preferably 1% by weight or more and 15% by weight or less. The content of the iodine in the polarizing film is preferably 1.5% by weight or more, more preferably 2% by weight or more, from the viewpoint of suppressing color loss during a durability test, and From the viewpoint of preventing polyene formation, it is preferably 12% by weight or less, and more preferably 10% by weight or less.

When the polarizing film contains the compound having a nitroxyl radical or a nitroxide group, the content of the compound having a nitroxyl radical or a nitroxide group is preferably 20% by weight or less. In the polarizing film, the content of the compound having a nitroxyl radical or a nitroxide group is 0.005% by weight or more from the viewpoint of suppressing a decrease in single transmittance due to coloring of the polarizing film in a high temperature environment. Is more preferable, 0.01% by weight or more is more preferable, 0.1% by weight or more is further preferable, and 15% by weight or less is preferable, and 12% by weight or less is more preferable. It is preferably 10% by weight or less, and more preferably 10% by weight or less.

<Method of manufacturing polarizing film>
The method for producing the polarizing film can be obtained by subjecting the polyvinyl alcohol-based film to an arbitrary swelling step and a washing step, and at least a dyeing step, a crosslinking step, and a stretching step. When the polarizing film contains the nitroxy radical or a compound having a nitroxide group, any one or more treatment steps of the swelling step, the washing step, the dyeing step, the crosslinking step, and the stretching step. It is sufficient that the treatment bath in 1 contains the above-mentioned nitroxy radical or a compound having a nitroxide group. The content of the compound having a nitroxy radical or a nitroxide group and the content of iodine contained in the polarizing film is any one of the treatment baths in the swelling step, the dyeing step, the crosslinking step, the stretching step and the washing step. It can be controlled by the concentration of the compound having a nitroxyl radical or a nitroxide group contained in the above, the concentration of iodine and potassium iodide, the treatment temperature and the treatment time in each treatment bath described above. In particular, when the washing step is performed after the dyeing step, the cross-linking step, and the stretching step, the washing step considers the treatment conditions in the dyeing step, the cross-linking step, and the stretching step, and then the nitroxy radical, Alternatively, from the viewpoint that a compound having a nitroxide group or a component such as iodine can be eluted from a polyvinyl alcohol-based film or adsorbed to a polyvinyl alcohol-based film, the content of the nitroxy radical or a compound having a nitroxide group and the iodine. It is easy to adjust the content of to the desired range.

Further, each treatment bath in the swelling step, the dyeing step, the crosslinking step, the stretching step and the washing step contains an additive such as a zinc salt, a pH adjusting agent, a pH buffering agent and other salts. May be. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide; inorganic zinc salts such as zinc sulfate and zinc acetate. Examples of the pH adjuster include strong acids such as hydrochloric acid, sulfuric acid and nitric acid, and strong bases such as sodium hydroxide and potassium hydroxide. Examples of the pH buffer include carboxylic acids such as acetic acid, oxalic acid and citric acid and salts thereof, and weak inorganic acids such as phosphoric acid and carbonic acid and salts thereof. Examples of the other salts include chlorides such as sodium chloride, potassium chloride and barium chloride, nitrates such as sodium nitrate and potassium nitrate, sulfates such as sodium sulfate and potassium sulfate, and alkali metals and alkaline earth metals. Salt etc. are mentioned.

The concentration of the nitroxy radical or the compound having a nitroxide group contained in any one of the treatment baths cannot be unconditionally determined because it is affected by the treatment number of each treatment, treatment time, treatment temperature, etc. From the viewpoint of efficiently controlling the content of the compound having a nitroxy radical or a nitroxide group, the content is usually preferably 0.01% by weight or more, more preferably 0.05% by weight or more, It is more preferably 0.1% by weight or more, and preferably 30% by weight or less, more preferably 25% by weight or less, and further preferably 20% by weight or less.

The swelling step is a treatment step of immersing the polyvinyl alcohol-based film in a swelling bath, which can remove stains and blocking agents on the surface of the polyvinyl alcohol-based film, and can also be dyed by swelling the polyvinyl alcohol-based film. Unevenness can be suppressed. For the swelling bath, a medium containing water as a main component, such as water, distilled water, or pure water, is usually used. To the swelling bath, a surfactant, alcohol, etc. may be appropriately added according to a conventional method.

The temperature of the swelling bath is preferably about 10 to 60°C, more preferably about 15 to 45°C, and further preferably about 18 to 30°C. Further, the dipping time in the swelling bath cannot be unconditionally determined because the degree of swelling of the polyvinyl alcohol-based film is affected by the temperature of the swelling bath, but is preferably about 5 to 300 seconds, and 10 to 200 seconds. It is more preferably about 10 to 100 seconds, and further preferably about 20 to 100 seconds. The swelling step may be performed only once, or may be performed multiple times as necessary.

The dyeing step is a treatment step of immersing the polyvinyl alcohol-based film in a dyeing bath (iodine solution), and iodine can be adsorbed and oriented on the polyvinyl alcohol-based film. Usually, the iodine solution is preferably an aqueous iodine solution and contains iodine and iodide as a dissolution aid. Examples of the 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. Among these, potassium iodide is preferable from the viewpoint of controlling the content of potassium in the polarizing film.

The iodine concentration in the dye bath is preferably about 0.01 to 1% by weight, more preferably about 0.02 to 0.5% by weight. In the dye bath, the iodide concentration is preferably about 0.01 to 20% by weight, more preferably about 0.05 to 10% by weight, and about 0.1 to 5% by weight. It is more preferable that there is.

The temperature of the dyeing bath is preferably about 10 to 50°C, more preferably about 15 to 45°C, and further preferably about 18 to 35°C. Further, the immersion time in the dyeing bath cannot be unconditionally determined because the degree of dyeing of the polyvinyl alcohol film is affected by the temperature of the dyeing bath, but it is preferably about 10 to 300 seconds, and preferably 20 to 240 seconds. It is more preferable that the degree is approximately. The dyeing step may be performed only once, or may be performed multiple times as necessary.

The cross-linking step is a step of immersing the polyvinyl alcohol-based film in a treatment bath containing a boron compound (cross-linking bath), and the polyvinyl alcohol-based film is cross-linked by the boron compound, and the iodine molecule or the dye molecule is cross-linked. Can be adsorbed on the structure. Examples of the boron compound include boric acid, borate, and borax. The cross-linking bath is generally an aqueous solution, but may be, for example, a mixed solution of an organic solvent miscible with water and water. Further, the crosslinking bath may contain potassium iodide from the viewpoint of controlling the content of potassium in the polarizing film.

The concentration of the boron compound in the crosslinking bath is preferably about 1 to 15% by weight, more preferably about 1.5 to 10% by weight, and even more preferably about 2 to 5% by weight. preferable. When potassium iodide is used in the crosslinking bath, the concentration of potassium iodide in the crosslinking bath is preferably about 1 to 15% by weight, and about 1.5 to 10% by weight. More preferably, it is more preferably about 2 to 5% by weight.

The temperature of the crosslinking bath is preferably about 20 to 70°C, more preferably about 30 to 60°C. Further, the immersion time in the crosslinking bath cannot be unconditionally determined because the degree of crosslinking of the polyvinyl alcohol film is influenced by the temperature of the crosslinking bath, but it is preferably about 5 to 300 seconds, and 10 to 200 seconds. It is more preferable that the degree is approximately. The cross-linking step may be performed only once, or may be performed multiple times as necessary.

The stretching step is a treatment step of stretching the polyvinyl alcohol-based film in at least one direction at a predetermined ratio. Generally, a polyvinyl alcohol film is uniaxially stretched in the transport direction (longitudinal direction). The stretching method is not particularly limited, and either a wet stretching method or a dry stretching method can be adopted. The stretching step may be performed only once, or may be performed multiple times as necessary. The stretching process may be performed at any stage in manufacturing the polarizing film.

As the treatment bath (stretching bath) in the wet stretching method, usually, water or a solvent such as a mixed solution of water and an organic solvent miscible with water can be used. The stretching bath may contain potassium iodide from the viewpoint of controlling the content of the potassium in the polarizing film. When potassium iodide is used in the drawing bath, the concentration of potassium iodide in the drawing bath is preferably about 1 to 15% by weight, more preferably about 2 to 10% by weight, and 3 More preferably, it is about 6% by weight. Further, the treatment bath (stretching bath) may contain the boron compound from the viewpoint of suppressing film breakage during stretching, and in this case, the concentration of the boron compound in the stretching bath is 1 to 15. The amount is preferably about wt%, more preferably about 1.5 to 10 wt%, and even more preferably about 2 to 5 wt%.

The temperature of the stretching bath is preferably about 25 to 80°C, more preferably about 40 to 75°C, and further preferably about 50 to 70°C. The dipping time in the stretching bath cannot be unconditionally determined because the extent of stretching of the polyvinyl alcohol-based film is affected by the temperature of the stretching bath, but it is preferably about 10 to 800 seconds, and 30 to 500 seconds. It is more preferable that the degree is approximately. The stretching treatment in the wet stretching method may be performed together with one or more treatment steps of the swelling step, the dyeing step, the crosslinking step, and the washing step.

Examples of the dry stretching method include a roll stretching method, a heating roll stretching method, and a compression stretching method. The dry stretching method may be performed together with the drying step.

The total draw ratio (cumulative draw ratio) applied to the polyvinyl alcohol-based film can be appropriately set according to the purpose, but is preferably about 2 to 7 times, and preferably about 3 to 6.8 times. More preferably, it is more preferably about 3.5 to 6.5 times.

The washing step is a treatment step of immersing the polyvinyl alcohol-based film in a washing bath and can remove foreign matter remaining on the surface of the polyvinyl alcohol-based film and the like. For the cleaning bath, a medium containing water as a main component, such as water, distilled water, or pure water, is usually used. Further, from the viewpoint of controlling the content of potassium in the polarizing film, the cleaning bath may contain potassium iodide, and in this case, the concentration of potassium iodide in the cleaning bath is 1 to 10% by weight. %, more preferably about 1.5 to 4% by weight, still more preferably about 1.8 to 3.8% by weight.

The temperature of the washing bath is preferably about 5 to 50°C, more preferably about 10 to 40°C, and even more preferably about 15 to 30°C. The immersion time in the cleaning bath cannot be unconditionally determined because the cleaning degree of the polyvinyl alcohol film is affected by the temperature of the cleaning bath, but it is preferably about 1 to 100 seconds, and 2 to 50 seconds. It is more preferably about 3 to 20 seconds. The swelling step may be performed only once, or may be performed multiple times as necessary.

The method of manufacturing the polarizing film may include a drying step. The drying step is a step of drying the polyvinyl alcohol film washed in the washing step to obtain a polarizing film, and by drying, a polarizing film having a desired moisture content is obtained. The drying is performed by any appropriate method, and examples thereof include natural drying, blast drying, and heat drying.

The drying temperature is preferably about 20 to 150°C, more preferably about 25 to 100°C. The drying time cannot be unconditionally determined because the drying degree of the polarizing film is affected by the drying temperature, but is preferably about 30 to 600 seconds, more preferably about 60 to 300 seconds. preferable. The drying step may be performed only once, or may be performed multiple times as necessary.

The polarizing film preferably has a thickness of about 1 to 50 μm, more preferably about 1 to 25 μm. In particular, in order to obtain a polarizing film having a thickness of 8 μm or less, the following thin type using a laminate including a polyvinyl alcohol-based resin layer formed on a resin substrate such as a thermoplastic resin as the polyvinyl alcohol-based film The manufacturing method of the polarizing film can be applied.

<Method for manufacturing polarizing film (thin polarizing film)>
The method for producing a polarizing film (thin polarizing film) includes a step of forming a polyvinyl alcohol-based resin layer containing a polyvinyl alcohol-based resin on one side of a long thermoplastic resin substrate, and preparing a laminate, While transporting the obtained laminate in the longitudinal direction, an insolubilization treatment step, a crosslinking treatment step, and a washing treatment step are performed on the laminate, and at least an in-air auxiliary stretching treatment step, a dyeing treatment step, and an underwater stretching treatment step. It is obtained by applying. When the polarizing film contains the compound having a nitroxyl radical or a nitroxide group, any one of the insolubilization treatment step, the crosslinking treatment step, the washing treatment step, the dyeing treatment step, and the underwater stretching treatment step It suffices that the treatment bath in one or more treatment steps contains the nitroxy radical or a compound having a nitroxide group. The nitroxy radical contained in the polarizing film, or the content of the compound having a nitroxide group and the content of iodine, the insolubilization treatment step, the crosslinking treatment step, the cleaning treatment step, the dyeing treatment step, and Concentration of the compound having a nitroxy radical or a nitroxide group contained in any of the treatment baths in the underwater stretching treatment step, and concentrations of iodine and potassium iodide, treatment temperature and treatment time in each treatment bath described above. Can be controlled by. In particular, in the case of applying a washing treatment step, the washing treatment step should be performed in consideration of treatment conditions such as a dyeing treatment step and an underwater stretching treatment step, and then a compound such as a compound having a nitroxyl radical or a nitroxide group or iodine. From the viewpoint of being able to be eluted from the polyvinyl alcohol-based film or adsorbed to the polyvinyl alcohol-based film, it is easy to adjust the content of the compound having a nitroxy radical or a nitroxide group and the content of iodine to a desired range.

The concentration of the nitroxy radical or the compound having a nitroxide group contained in any one of the treatment baths cannot be unconditionally determined because it is affected by the treatment number of each treatment, treatment time, treatment temperature, etc. From the viewpoint of efficiently controlling the content of the compound having a nitroxy radical or a nitroxide group, the content is usually preferably 0.01% by weight or more, more preferably 0.05% by weight or more, It is more preferably 0.1% by weight or more, and preferably 30% by weight or less, more preferably 25% by weight or less, and further preferably 20% by weight or less.

<Process of preparing laminated body>
Any appropriate method is adopted as a method for producing the laminate, and for example, a coating solution containing the polyvinyl alcohol resin (PVA resin) is applied to the surface of the thermoplastic resin substrate and dried. There is a way to do it. The thickness of the thermoplastic resin substrate is preferably about 20 to 300 μm, more preferably about 50 to 200 μm. The thickness of the PVA-based resin layer is preferably about 3 to 40 μm, more preferably about 3 to 20 μm.

The thermoplastic resin substrate preferably has a water absorption rate of about 0.2% or more from the viewpoint of absorbing water to significantly reduce the stretching stress and allowing stretching at a high ratio, and 0.3 % Or more is more preferable. On the other hand, the thermoplastic resin base material has a water absorption of 3 from the viewpoint that the dimensional stability of the thermoplastic resin base material is remarkably reduced and the appearance of the obtained polarizing film is deteriorated. % Or less, more preferably about 1% or less. The water absorption can be adjusted, for example, by introducing a modifying group into the constituent material of the thermoplastic resin substrate. The water absorption rate is a value determined according to JIS K 7209.

The thermoplastic resin base material has a glass transition temperature (Tg) of about 120° C. or lower from the viewpoint of being able to sufficiently secure the stretchability of the laminate while suppressing the crystallization of the PVA-based resin layer. Is preferred. Further, in consideration of the plasticization of the thermoplastic resin substrate with water and the favorable underwater drawing, the glass transition temperature (Tg) is more preferably about 100° C. or lower, and about 90° C. or lower. Is more preferable. On the other hand, the glass transition temperature of the thermoplastic resin substrate is such that when the coating liquid is applied and dried, problems such as deformation of the thermoplastic resin substrate can be prevented and a good laminate can be produced. Therefore, the temperature is preferably about 60° C. or higher. The glass transition temperature can be adjusted, for example, by introducing a modifying group into the constituent material of the thermoplastic resin substrate or by heating with a crystallization material. The glass transition temperature (Tg) is a value determined according to JIS K 7121.

Any appropriate thermoplastic resin can be adopted as a constituent material of the thermoplastic resin substrate. Examples of the thermoplastic resin include ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene, polyamide resins, polycarbonate resins, and copolymer resins thereof. Etc. Among these, norbornene-based resins and amorphous (amorphous) polyethylene terephthalate-based resins are preferable. Further, the thermoplastic resin base material has extremely excellent stretchability, and from the viewpoint that crystallization during stretching can be suppressed. Amorphous (non-crystalline) polyethylene terephthalate resin is preferably used. Examples of the amorphous (amorphous) polyethylene terephthalate-based resin include a copolymer containing isophthalic acid and/or cyclohexanedicarboxylic acid as a dicarboxylic acid, and a copolymer containing cyclohexanedimethanol or diethylene glycol as a glycol.

The thermoplastic resin substrate may be subjected to a surface treatment (for example, corona treatment) before forming the PVA-based resin layer, or an easy adhesion layer may be formed on the thermoplastic resin substrate. .. By performing such a treatment, it is possible to improve the adhesion between the thermoplastic resin substrate and the PVA-based resin layer. The thermoplastic resin substrate may be stretched before forming the PVA-based resin layer.

The coating liquid is a solution in which a PVA resin is dissolved in a solvent. Examples of the solvent include water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, amines such as ethylenediamine and diethylenetriamine, and water. preferable. These can be used alone or in combination of two or more. The concentration of the PVA-based resin in the coating liquid is preferably about 3 to 20 parts by weight with respect to 100 parts by weight of the solvent, from the viewpoint of being able to form a uniform coating film in close contact with the thermoplastic resin substrate. ..

From the viewpoint of improving the orientation of polyvinyl alcohol molecules by stretching, it is preferable that the coating liquid contains a halide. Any appropriate halide can be adopted as the halide, and examples thereof include iodide and sodium chloride. Examples of the iodide include potassium iodide, sodium iodide, lithium iodide and the like, and potassium iodide is preferable. The concentration of the halide in the coating liquid is preferably about 5 to 20 parts by weight, more preferably about 10 to 15 parts by weight, based on 100 parts by weight of the PVA-based resin.

Moreover, you may mix|blend an additive with the said coating liquid. Examples of the additives include plasticizers such as ethylene glycol and glycerin; surfactants such as nonionic surfactants.

Any appropriate method can be adopted as a method for applying the coating solution, for example, a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, a die coating method, a curtain coating method, a spray coating method. , Knife coating method (comma coating method, etc.) and the like. The drying temperature of the coating liquid is preferably about 50°C or higher.

<Air-assisted stretching process>
In the in-air auxiliary stretching treatment step, stretching can be performed while suppressing crystallization of the thermoplastic resin substrate, so that the laminate can be stretched at a high ratio. The stretching method of the in-air auxiliary stretching treatment step may be fixed-end stretching (for example, a method of stretching using a tenter stretching machine) or free-end stretching (for example, uniaxial stretching through a laminate between rolls having different peripheral speeds). Method), but free end drawing is preferable from the viewpoint of obtaining high optical characteristics.

The draw ratio in the in-air auxiliary drawing process is preferably about 2 to 3.5 times. The in-air auxiliary stretching treatment may be performed in one stage or in multiple stages. When performing in multiple stages, the draw ratio is the product of the draw ratios of the respective stages.

The stretching temperature in the in-air auxiliary stretching treatment step can be set to any appropriate value depending on the forming material of the thermoplastic resin substrate, the stretching method, and the like. For example, the glass transition temperature of the thermoplastic resin substrate. It is preferably (Tg) or higher, more preferably the glass transition temperature (Tg)+10° C. or higher, and further preferably the glass transition temperature (Tg)+15° C. or higher. On the other hand, the upper limit of the stretching temperature is from the viewpoint that the crystallization of the PVA-based resin can be prevented from rapidly progressing and defects due to crystallization (for example, hindering the orientation of the PVA-based resin layer due to the stretching) can be suppressed. It is preferably about 170°C.

<Insolubilization process>
If necessary, an insolubilization treatment step may be performed after the in-air auxiliary stretching treatment step and before the dyeing treatment step or the underwater stretching treatment step. The insolubilization treatment step is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing the insolubilization treatment step, it is possible to impart water resistance to the PVA-based resin layer and prevent the orientation of PVA from being lowered when immersed in water. The concentration of the boric acid aqueous solution is preferably about 1 to 5 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the insolubilization bath is preferably about 20 to 50°C.

<Dyeing process>
The dyeing treatment step is performed by dyeing the PVA-based resin layer with iodine. Examples of the adsorption method include a method of immersing the PVA-based resin layer (laminate) in a dyeing solution containing iodine, a method of applying the dyeing solution to the PVA-based resin layer, and a method of applying the dyeing solution to the PVA-based resin layer. Examples thereof include a method of spraying, and a method of immersing the PVA-based resin layer (laminate) in a dyeing solution containing iodine is preferable.

The blending amount of iodine in the dyeing bath is preferably about 0.05 to 0.5 parts by weight with respect to 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add the iodide to the aqueous iodine solution. The amount of the iodide compounded is preferably about 0.1 to 10 parts by weight, more preferably about 0.3 to 5 parts by weight, based on 100 parts by weight of water. The liquid temperature of the dyeing bath is preferably about 20 to 50° C. in order to suppress dissolution of the PVA-based resin. Further, the immersion time is preferably about 5 seconds to 5 minutes, and more preferably about 30 seconds to 90 seconds, from the viewpoint of ensuring the transmittance of the PVA-based resin layer. From the viewpoint of obtaining a polarizing film having good optical properties, the ratio of the content of iodine and iodide in the aqueous iodine solution is preferably about 1:5 to 1:20, and about 1:5 to 1:10. More preferably.

<Crosslinking process>
If necessary, a crosslinking treatment step may be performed after the dyeing treatment step and before the underwater stretching treatment step. The cross-linking treatment step is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing the cross-linking treatment step, it is possible to impart water resistance to the PVA-based resin layer and prevent the PVA from lowering in orientation when it is immersed in high-temperature water in the subsequent underwater stretching. The boric acid concentration of the aqueous boric acid solution is preferably about 1 to 5 parts by weight with respect to 100 parts by weight of water. Further, when the crosslinking treatment step is performed, it is preferable that the crosslinking bath further contains the iodide. By blending the iodide, the elution of iodine adsorbed on the PVA-based resin layer can be suppressed. The iodide content is preferably about 1 to 5 parts by weight with respect to 100 parts by weight of water. The liquid temperature of the crosslinking bath (boric acid aqueous solution) is preferably about 20 to 50°C.

<Underwater stretching process>
The underwater stretching treatment step is performed by immersing the laminate in a stretching bath. According to the underwater stretching treatment step, it is possible to stretch at a temperature lower than the glass transition temperature (typically about 80° C.) of the thermoplastic resin base material or the PVA type resin layer, and the PVA type resin layer is crystallized. It is possible to stretch at a high magnification while suppressing the above. The stretching method in the underwater stretching treatment step may be fixed-end stretching (for example, a stretching method using a tenter stretching machine) or free-end stretching (for example, a uniaxial stretching method in which a laminate is passed between rolls having different peripheral speeds). ) May be used, but free-end stretching is preferable from the viewpoint of obtaining high optical characteristics.

The underwater stretching treatment step is preferably performed by immersing the laminate in a boric acid aqueous solution (boric acid underwater stretching). By using an aqueous boric acid solution as the stretching bath, the PVA-based resin layer can be provided with rigidity that can withstand the tension applied during stretching and water resistance that does not dissolve in water. The boric acid concentration of the boric acid aqueous solution is preferably 1 to 10 parts by weight, and more preferably 2.5 to 6 parts by weight with respect to 100 parts by weight of water. Moreover, you may mix|blend an iodide with the said drawing bath (boric-acid aqueous solution). The liquid temperature of the stretching bath is preferably about 40 to 85°C, more preferably about 60°C to 75°C. The immersion time of the laminate in the stretching bath is preferably about 15 seconds to 5 minutes.

The draw ratio in the underwater drawing step is preferably about 1.5 times or more, and more preferably about 3 times or more.

The total draw ratio of the laminate is preferably about 5 times or more, and more preferably about 5.5 times or more of the original length of the laminate.

<Cleaning process>
It is preferable to perform a washing process after the underwater stretching process. The cleaning treatment step is typically performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

Further, each treatment bath in the dyeing treatment step, the underwater stretching treatment step, the insolubilization treatment step, the cross-linking treatment step, and the washing treatment step contains zinc salt, a pH adjusting agent, a pH buffering agent, and other salts. It may contain various additives. Examples of the zinc salt include zinc halides such as zinc chloride and zinc iodide; inorganic zinc salts such as zinc sulfate and zinc acetate. Examples of the pH adjuster include strong acids such as hydrochloric acid, sulfuric acid and nitric acid, and strong bases such as sodium hydroxide and potassium hydroxide. Examples of the pH buffer include carboxylic acids such as acetic acid, oxalic acid and citric acid and salts thereof, and weak inorganic acids such as phosphoric acid and carbonic acid and salts thereof. Examples of the other salts include chlorides such as sodium chloride, potassium chloride and barium chloride, nitrates such as sodium nitrate and potassium nitrate, sulfates such as sodium sulfate and potassium sulfate, and alkali metals and alkaline earth metals. Salt etc. are mentioned.

<Adhesive layer>
As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer of the present invention, various pressure-sensitive adhesives used in polarizing films can be applied, and examples thereof include a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, and a urethane-based pressure-sensitive adhesive. , Vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinyl porolidone-based adhesives, polyacrylamide-based adhesives, and cellulose-based adhesives. Among these, acrylic adhesives are suitable. The acrylic pressure-sensitive adhesive contains an acrylic polymer as a base polymer, and examples thereof include the acrylic pressure-sensitive adhesives described in JP-A-2017-75998.

The acrylic polymer in the acrylic pressure-sensitive adhesive has a monomer unit of (meth)acrylic acid alkyl ester as a main skeleton. As the (meth)acrylic acid alkyl ester, a (meth)acrylic acid alkyl ester having an alkyl group having 1 to 20 carbon atoms is preferably used, and the content of the (meth)acrylic acid alkyl ester is the base polymer. It is preferably 40% by weight or more, more preferably 60% by weight or more, based on the total amount of the constituent monomer components. Further, from the viewpoint of adjusting the adhesiveness of the pressure-sensitive adhesive, it may contain a monomer unit such as a nitrogen-containing monomer unit or a hydroxy group-containing monomer. Further, in order to form a crosslinked structure in the pressure-sensitive adhesive layer, a crosslinking agent may be used, and examples of the crosslinking agent include an isocyanate crosslinking agent, an epoxy crosslinking agent, an oxazoline crosslinking agent, an aziridine crosslinking agent, and a carbodiimide crosslinking agent. Commonly used crosslinking agents, metal chelate crosslinking agents, etc. can be used. The amount of the crosslinking agent used is usually 10 parts by weight or less, preferably 5 parts by weight or less, based on 100 parts by weight of the base polymer.

From the viewpoint of adjusting the adhesive strength, the pressure-sensitive adhesive includes silane coupling agents; terpene-based tackifiers, styrene-based tackifiers, phenol-based tackifiers, rosin-based tackifiers, epoxy-based tackifiers, and the like. A tackifier may be added. Further, from the viewpoint of improving the light resistance, an ultraviolet absorber may be added. In addition to the above-exemplified components, the pressure-sensitive adhesive may include additives such as a plasticizer, a softening agent, a deterioration inhibitor, a filler, a colorant, an antioxidant, a surfactant, and an antistatic agent. Can be used within a range that does not impair

As a method of forming the pressure-sensitive adhesive layer, for example, a method of applying the pressure-sensitive adhesive to a release-treated separator or the like, forming a pressure-sensitive adhesive layer by drying, and then transferring to a polarizing film, or the pressure-sensitive adhesive is polarized. Examples thereof include a method of forming a pressure-sensitive adhesive layer by applying it on a film or the like and drying it. The thickness of the pressure-sensitive adhesive layer is not particularly limited and is, for example, about 1 to 100 μm, and preferably about 2 to 50 μm.

<Adhesive layer>
As the adhesive forming the adhesive layer of the present invention, various adhesives used in polarizing films can be applied, and examples thereof include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex. System, water-based polyester and the like. These adhesives are usually used as an adhesive composed of an aqueous solution (water-based adhesive), and contain 0.5 to 60% by weight of solid content. Among these, polyvinyl alcohol adhesives are preferable, and acetoacetyl group-containing polyvinyl alcohol adhesives are more preferable.

The water-based adhesive may contain a crosslinking agent. As the cross-linking agent, a compound having at least two functional groups reactive with a component such as a polymer constituting an adhesive in one molecule is usually used, and examples thereof include alkylenediamines; isocyanates; epoxies; Aldehydes; amino-formaldehyde such as methylol urea and methylol melamine. The content of the cross-linking agent in the adhesive is usually about 10 to 60 parts by weight with respect to 100 parts by weight of the components such as the polymer constituting the adhesive.

In addition to the above, examples of the adhesive include active energy ray-curable adhesives such as UV-curable adhesives and electron beam-curable adhesives. Examples of the active energy ray-curable adhesive include (meth)acrylate adhesives. Examples of the curable component in the (meth)acrylate-based adhesive include compounds having a (meth)acryloyl group and compounds having a vinyl group. Examples of the compound having a (meth)acryloyl group include alkyl (meth) such as chain alkyl (meth)acrylate having 1 to 20 carbon atoms, alicyclic alkyl (meth)acrylate, and polycyclic alkyl (meth)acrylate. ) Acrylate; hydroxyl group-containing (meth)acrylate; epoxy group-containing (meth)acrylate such as glycidyl (meth)acrylate. (Meth)acrylate adhesives include hydroxyethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, (meth)acrylamide, (meth) It may contain a nitrogen-containing monomer such as acryloylmorpholine. The (meth)acrylate adhesive is a cross-linking component of tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane formal acrylate, dioxane glycol diacrylate, EO. It may contain a polyfunctional monomer such as modified diglycerin tetraacrylate. Further, a compound having an epoxy group or an oxetanyl group can also be used as the cationic polymerization curable adhesive. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various commonly known curable epoxy compounds can be used.

The adhesive may contain an appropriate additive as needed. Examples of the additives include silane coupling agents, coupling agents such as titanium coupling agents, adhesion promoters such as ethylene oxide, ultraviolet absorbers, deterioration inhibitors, dyes, processing aids, ion trap agents, and antioxidants. Agents, tackifiers, fillers, plasticizers, leveling agents, foaming inhibitors, antistatic agents, heat resistance stabilizers, hydrolysis resistance stabilizers and the like.

The adhesive may be applied to either the transparent protective film side (or the functional layer side described later) described later, the polarizing film side, or both. After the bonding, a drying process is performed to form an adhesive layer composed of a coating and drying layer. After the drying step, ultraviolet rays or an electron beam can be irradiated if necessary. The thickness of the adhesive layer is not particularly limited, and when an aqueous adhesive or the like is used, it is preferably about 30 to 5000 nm, more preferably about 100 to 1000 nm, and an ultraviolet curable adhesive. When using an electron beam curable adhesive or the like, the thickness is preferably about 0.1 to 100 μm, more preferably about 0.5 to 10 μm.

When the pressure-sensitive adhesive layer or the adhesive layer contains the compound having a nitroxyl radical or a nitroxide group, the content of the compound having a nitroxyl radical or a nitroxide group is the coloring of the polarizing film under a high temperature environment. From the viewpoint of suppressing a decrease in simple substance transmittance due to the above, it is preferably 1% by weight or more, more preferably 5% by weight or more, and further preferably 10% by weight or more in the pressure-sensitive adhesive layer or the adhesive layer. More preferably, it is preferably 70% by weight or less, and more preferably 50% by weight or less.

<Single-sided protective polarizing film and double-sided protective polarizing film>
In the one-sided protective polarizing film of the present invention, a transparent protective film is attached to at least one surface of the polarizing film via the pressure-sensitive adhesive layer or the adhesive layer. In the double-sided protective polarizing film of the present invention, a transparent protective film is attached to both sides of the polarizing film via the pressure-sensitive adhesive layer or the adhesive layer.

The transparent protective film is not particularly limited, and various transparent protective films used for polarizing films can be used. As a material forming the transparent protective film, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropic property, etc. is used. Examples of the thermoplastic resin include cellulose ester resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone resins, polysulfone resins, polycarbonate resins, nylon and aroma. Polyamide resins such as group polyamides, polyimide resins, polyolefin resins such as polyethylene, polypropylene and ethylene-propylene copolymers, (meth)acrylic resins, cyclo polyolefin resins having a norbornene structure (norbornene resins) ), polyarylate-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, and mixtures thereof. Further, the transparent protective film may use a cured layer formed of a thermosetting resin such as a (meth)acrylic resin, a urethane resin, an acryl urethane resin, an epoxy resin, a silicone resin or an ultraviolet curable resin. Among these, a cellulose ester resin, a polycarbonate resin, a (meth)acrylic resin, a cyclic polyolefin resin, and a polyester resin are preferable.

The thickness of the transparent protective film can be appropriately determined, but generally, from the viewpoint of workability such as strength and handleability, thin layer property, etc., it is preferably about 1 to 500 μm, and about 1 to 300 μm. It is more preferable that the thickness is about 5 to 100 μm.

In the transparent protective film, the compound having a nitroxyl radical or a nitroxide group moves inside the image display device together with the water present in the image display device (water present in the adhesive layer or the adhesive layer). From the viewpoint of making the polarizing film easily stagnate and permeate into the polarizing film, the water vapor transmission rate is preferably 50 g/(m ² ·24 h or more, more preferably 100 g/(m ² ·24 h) or more, and 200 g/( It is more preferable that the water vapor transmission rate is not less than m ² ·24h), and the water vapor transmission rate according to the water vapor transmission rate test (cup method) of JIS Z0208. It is calculated by measuring the weight increase of calcium chloride before and after standing for 24 hours after placing it in a thermostat having a temperature of 40° C. and a humidity of 90% RH.

When the transparent protective films are attached to both sides of the polarizing film, the transparent protective films on both sides may be the same or different.

As the transparent protective film, a retardation plate having a front surface retardation 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 also functions as a transparent protective film, so that the thickness can be reduced.

Examples of the retardation plate include birefringent films obtained by uniaxially or biaxially stretching a polymer material, liquid crystal polymer alignment films, and liquid crystal polymer alignment layers supported by films. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm. The phase plate may be attached to a transparent protective film having no retardation.

The transparent protective film contains any appropriate additive such as an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a release agent, an anti-coloring agent, a flame retardant, an antistatic agent, a pigment and a colorant. You may stay. In particular, when the transparent protective film contains an ultraviolet absorber, the light resistance of the polarizing film can be improved.

A functional layer such as a hard coat layer, an antireflection layer, an antisticking layer, a diffusion layer or an antiglare layer can be provided on the surface of the transparent protective film to which the polarizing film is not attached. The hard coat layer, the antireflection layer, the antisticking layer, the functional layer such as the diffusion layer and the antiglare layer may be provided on the protective film itself, or may be provided separately from the protective film. it can.

The polarizing film and the transparent protective film, or the polarizing film and the functional layer are usually attached via the pressure-sensitive adhesive layer or the adhesive layer.

The transparent protective film and the polarizing film, or the polarizing film and the functional layer may be laminated via an intervening layer such as a surface modification treatment layer, an easy-adhesive layer, a block layer, and a refractive index adjusting layer. ..

Examples of the surface modification treatment for forming the surface modification layer include corona treatment, plasma treatment, primer treatment, saponification treatment and the like.

Examples of the easy-adhesive agent for forming the easy-adhesion layer include a forming material containing various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone-based, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, or the like. Can be mentioned. The easy-adhesion layer is usually provided in advance on the protective film, and the easy-adhesion layer side of the protective film and the polarizing film are laminated with the pressure-sensitive adhesive layer or the adhesive layer.

The block layer is a layer having a function of preventing impurities (such as oligomers and ions) eluted from the transparent protective film and the like from moving (entering) into the polarizing film. The block layer may be any layer as long as it has transparency and can prevent impurities eluted from the transparent protective film and the like, and examples of the material for forming the block layer include urethane prepolymer-based forming material and cyanoacrylate. Examples include a system forming material and an epoxy forming material.

The refractive index adjusting layer is a layer provided for suppressing a decrease in transmittance due to reflection between the transparent protective film and a layer having a different refractive index such as a polarizing film. Examples of the refractive index adjusting material forming the refractive index adjusting layer include a forming agent containing various resins and additives having a silica type, an acrylic type, an acryl-styrene type, a melamine type, or the like.

The polarizing film of the present invention has a general formula (1): X (% by weight)>0.01 (in the general formula (1), from the viewpoint of suppressing a decrease in simple substance transmittance due to coloring of the polarizing film in a high temperature environment, X is a laminated body in which a glass plate is bonded to both surfaces of a polarizing film having the transparent protective film bonded to at least one surface of the polarizing film via the adhesive layer at 105° C. , The content of the compound having a nitroxide radical or a nitroxide group in the polarizing film in the laminate left under the condition of 24 hours is shown.). The X (% by weight) is preferably 0.02 or more, and more preferably 0.05 or more.

<Laminated polarizing film>
The laminated polarizing film (optical laminate) of the present invention has an optical layer bonded to at least one surface of the single-sided protective polarizing film or the double-sided protective polarizing film via the pressure-sensitive adhesive layer or the adhesive layer. There is something.

The optical layer is not particularly limited, but for example, for forming a liquid crystal display device such as a reflection plate, a semi-transmission plate, a retardation plate (including a wavelength plate such as 1/2 or 1/4), and a viewing angle compensation film. One or two or more optical layers that may be used can be used. As the laminated polarizing film, in particular, a reflective polarizing film or a semi-transmissive polarizing film obtained by further laminating a reflecting plate or a semi-transmissive reflecting plate on the polarizing film, and further comprising a retardation plate laminated on the polarizing film. Examples thereof include an elliptically polarizing film or a circularly polarizing film, a wide viewing angle polarizing film obtained by further laminating a viewing angle compensation film on the polarizing film, or a polarizing film obtained by further laminating a brightness improving film on the polarizing film.

One side or both sides of the single-sided protective polarizing film, the double-sided protective polarizing film, or the laminated polarizing film has an image display cell such as a liquid crystal cell or an organic EL element, and a front transparent plate or a touch panel on the viewing side. The pressure-sensitive adhesive layer or the adhesive layer may be attached in advance in order to bond other members such as the front transparent member. In this way, the polarizing film or the laminated polarizing film having a pressure-sensitive adhesive layer provided on at least one surface thereof has a pressure-sensitive adhesive layer-attached single-sided protective polarizing film, a pressure-sensitive adhesive layer-attached double-sided protective polarizing film, or a pressure-sensitive adhesive layer. With laminated polarizing film.

It is preferable that the exposed surface of the pressure-sensitive adhesive layer or the adhesive layer is temporarily attached and covered with a separator for the purpose of preventing contamination or the like until it is put into practical use. This can prevent the pressure-sensitive adhesive layer or the adhesive layer from being contaminated in the usual handling state. As the separator, for example, a plastic film, a rubber sheet, a paper, a cloth, a non-woven fabric, a net, a foam sheet or a metal foil, an appropriate thin sheet such as a laminate thereof, a silicone-based or long-chain alkyl-based, if necessary, Those coated with an appropriate release agent such as fluorine-based or molybdenum sulfide are used.

<Front transparent member>
The front transparent member of the present invention is a front transparent member arranged on the visible side of the image display cell. Examples of the front transparent member include a front transparent plate (window layer) and a touch panel. As the front transparent plate, a front transparent plate having appropriate mechanical strength and thickness is used. As such a transparent plate, for example, a transparent resin plate such as an acrylic resin or a polycarbonate resin, or a glass plate is used. As the touch panel, for example, various touch panels such as a resistance film type, a capacitance type, an optical type, an ultrasonic type, and a glass plate or a transparent resin plate having a touch sensor function are used. When a capacitive touch panel is used as the front transparent member, it is preferable that a front transparent plate made of glass or a transparent resin plate is provided on the side closer to the viewer than the touch panel.

<Image display cell>
Examples of the image display cell of the present invention include a liquid crystal cell and an organic EL cell. Examples of the liquid crystal cell include a reflective liquid crystal cell that uses external light, a transmissive liquid crystal cell that uses light from a light source such as a backlight, and a semi-transmissive liquid crystal cell that uses both external light and light from a light source. Any of the semi-reflective liquid crystal cells may be used. When the liquid crystal cell utilizes light from a light source, the image display device (liquid crystal display device) has a polarizing film arranged on the side opposite to the viewing side of the image display cell (liquid crystal cell). Will be placed. It is preferable that the polarizing film on the light source side and the liquid crystal cell are bonded together via an appropriate adhesive layer. As a driving method of the liquid crystal cell, for example, any type such as a VA mode, an IPS mode, a TN mode, an STN mode, a bend alignment (π type), or the like can be used.

As the organic EL cell, for example, a cell in which a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitting body (organic electroluminescent light emitting body) and the like are preferably used. 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 or the like and a light emitting layer made of a fluorescent organic solid such as anthracene, or the like. Various layer configurations such as a laminated body of the above-mentioned light emitting layer and an electron injection layer composed of a perylene derivative or a laminated body of a hole injection layer, a light emitting layer, and an electron injection layer can be adopted.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

<Example 1>
<Production of polarizing film>
A polyvinyl alcohol film having an average degree of polymerization of 2,400, a degree of saponification of 99.9 mol% and a thickness of 45 μm was prepared. The polyvinyl alcohol film was dipped in a swelling bath (water bath) at 20° C. for 30 seconds between rolls having different peripheral speed ratios and stretched to 2.2 times in the transport direction while swelling (swelling step). The iodine concentration of the polarizing film finally obtained in a dyeing bath at 30° C. (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 to 100 parts by weight of water) is 4 It is soaked for 30 seconds while adjusting the concentration to be 0.47% by weight, and dyed 3.3 times in the transport direction based on the original polyvinyl alcohol film (polyvinyl alcohol film that has not been stretched in the transport direction) while dyeing. Was stretched (dyeing step). Then, the dyed polyvinyl alcohol film is immersed in a crosslinking bath at 40° C. (an aqueous solution having a boric acid concentration of 3.0% by weight and a potassium iodide concentration of 3.0% by weight) for 28 seconds to dip the original polyvinyl alcohol film. The film was stretched up to 3.6 times in the transport direction (crosslinking step). Further, the obtained polyvinyl alcohol film was immersed in a stretching bath at 61° C. (an aqueous solution having a boric acid concentration of 4.0% by weight and a potassium iodide concentration of 5.0% by weight) for 60 seconds to obtain the original polyvinyl alcohol film. After stretching to 6.0 times in the transport direction based on the alcohol film (stretching step), a washing bath at 35° C. (potassium iodide concentration of 2.0% by weight, nitroxy radical represented by the following general formula (9)) Or an aqueous solution in which the concentration of the compound having a nitroxide group is 0.4% by weight) for 10 seconds (washing step). The washed polyvinyl alcohol film was dried at 40° C. for 30 seconds to prepare a polarizing film. The content of the compound having a nitroxyl radical or a nitroxide group in the polarizing film determined by the following measuring method was 0.28% by weight, and the thickness of the polarizing film was 18 μm.

[Method of measuring content (% by weight) of compound having nitroxy radical or nitroxide group in polarizing film]
About 20 mg of a polarizing film was collected, quantified, dissolved by heating in 1 mL of water, diluted with 4.5 mL of methanol, the obtained extract was filtered through a membrane filter, and the filtrate was analyzed by HPLC (ACQUITY UPLC manufactured by Waters). The concentration of the compound having a nitroxy radical or a nitroxide group was measured using H-class Bio).

[Method of measuring iodine content (% by weight) in polarizing film]
With respect to the polarizing film, the iodine concentration (% by weight) was determined using the following formula using a fluorescent X-ray analyzer (Rigaku Corporation, trade name “ZSX-PRIMUS IV”, measurement diameter: ψ20 mm).
Iodine concentration (wt%) = 14.474 x (fluorescent X-ray intensity)/(film thickness) (kcps/μm) Although the coefficient for calculating the concentration differs depending on the measuring device, the coefficient is an appropriate calibration curve. Can be obtained using.

<Production of polarizing film>
As an adhesive, polyvinyl alcohol resin containing acetoacetyl group (average polymerization degree: 1,200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 mol%) and methylolmelamine in a weight ratio of 3: The aqueous solution contained in 1 was used. Using this adhesive, as a transparent protective film on both surfaces of the polarizing film obtained above, a triacetyl cellulose film having a hard coat layer and a thickness of 47 μm (moisture permeability 342 g/(m ² ·24 h), Konica Minolta (Product name: "KC4UYW") is pasted with a roll laminating machine, and then dried by heating in an oven (temperature is 60°C, time is 4 minutes), and transparent protective films are pasted on both sides of the polarizing film. The obtained polarizing film was produced. The single transmittance of the polarizing film was 37.4%.

<Preparation of acrylic adhesive>
A monomer mixture containing 99 parts by weight of butyl acrylate and 1 part by weight of 4-hydroxybutyl acrylate was charged into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a condenser. Further, with respect to 100 parts by weight of the monomer mixture (solid content), 0.1 parts by weight of 2,2′-azobisisobutyronitrile as a polymerization initiator was charged together with 100 parts by weight of ethyl acetate, and the mixture was gently stirred. After introducing nitrogen gas to replace the atmosphere with nitrogen, a polymerization reaction was carried out for 8 hours while maintaining the liquid temperature in the flask at about 55° C. to prepare a solution of an acrylic polymer having a weight average molecular weight (Mw) of 1.8 million. Then, with respect to 100 parts by weight of the solid content of the obtained acrylic polymer solution, 0.02 parts by weight of an isocyanate crosslinking agent (manufactured by Tosoh Corporation, trade name "Takenate D110N", trimethylolpropane/xylylene diisocyanate adduct). Then, 0.2 part by weight of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-41-1056") was mixed to prepare a solution of the acrylic pressure-sensitive adhesive composition. Then, the solution of the acrylic pressure-sensitive adhesive composition obtained above was dried on one surface of a polyethylene terephthalate film (manufactured by Mitsubishi Kagaku Polyester Film, trade name "MRF38", separator film) treated with a silicone-based release agent, after drying. The pressure-sensitive adhesive layer was applied so as to have a thickness of 20 μm and dried at 90° C. for 1 minute to form a pressure-sensitive adhesive layer on the surface of the separator film. Next, the pressure-sensitive adhesive layer formed on the separator film was transferred onto one surface of the polarizing film prepared above to prepare a polarizing film with a pressure-sensitive adhesive layer.

<Production of pseudo image display device (laminate)>
The protective polarizing film with the pressure-sensitive adhesive layer obtained above was cut into a size of 45×40 mm so that the absorption axis of the polarizing film became the long side, and a glass plate (pseudo image display cell) was cut through the pressure-sensitive adhesive layer. Laminating and bonding another glass plate (pseudo front transparent member) to the other surface of the polarizing film via a 200 μm thick acrylic acid monomer-free adhesive (manufactured by Nitto Denko Corporation, trade name “LUCIACS CS9868”) Thus, a pseudo image display device (laminated body) was produced.

[Evaluation of single transmittance in high temperature environment]
The pseudo image display device (laminate) obtained above was allowed to stand in a hot air oven at a temperature of 105° C. for 48 hours, and the single-body transmittance (ΔTs) before and after charging (heating) was measured. The simple substance transmittance was measured using a spectrophotometer (manufactured by Murakami Color Research Laboratory Co., Ltd., product name “DOT-3”), and evaluated according to the following criteria. The single-piece transmittance is a Y value that is luminosity-corrected by the 2 degree visual field (C light source) of JLS Z 8701-1982. The measurement wavelength is 380 to 700 nm (every 10 nm). The results are shown in Table 1.
ΔTs (%)=Ts ₄₈ −Ts ₀
Here, Ts ₀ is the single transmittance of the pseudo image display device (laminate) before heating, and Ts ₄₈ is the single transmittance of the pseudo image display device (laminate) after heating for 48 hours.
◯: 5≧ΔTs (%)≧0
X: ΔTs(%)>5 or ΔTs(%)<0

The ΔTs(%) is preferably 5≧ΔTs(%)≧0, and more preferably 4≧ΔTs(%)≧0.

[Measurement of Nitroxy Radical or Nitroxide Group-Containing Compound Content in Polarizing Film under High Temperature Environment]
The pseudo image display device (laminate) obtained above is allowed to stand in a hot air oven at a temperature of 105° C. for 24 hours, and has a nitroxy radical or a nitroxide group contained in the polarizing film after being charged (heated). The content of the compound was determined by the following method. The heated pseudo image display device was immersed in about 1000 mL of a solution of methylene chloride or toluene for 3 days or more, and the protective film was dissolved to take out the polarizing film. As a result, the polarizing film was about 40 mg. After washing the polarizing film with pure methylene chloride or toluene, about 1 mg of the polarizing film was sampled, quantified, dissolved by heating in 0.5 mL of water, diluted with 1 mL of methanol, and the obtained extract was used as a membrane. After filtering with a filter, the concentration of the compound having a nitroxyl radical or a nitroxide group was measured using LCMS (UltraMate 3000/LTQ orbitrap XL manufactured by Thermo Fisher Scientific).

<Example 2>
<Production of polarizing film, polarizing film, pseudo image display device (laminate)>
In the production of the polarizing film, both the adhesives to be used in the production of the polarizing film without adding the compound having the nitroxy radical or the nitroxide group represented by the general formula (9) to the cleaning bath are represented by the general formula ( A polarizing film was prepared in the same manner as in Example 1, except that the compound having a nitroxy radical or a nitroxide group represented by 9) was added so that the weight ratio with the polyvinyl alcohol resin was 4:3. A polarizing film and a pseudo image display device (laminate) were produced. The single transmittance of the polarizing film was 39.7%.

<Example 3>
<Production of polarizing film, polarizing film, pseudo image display device (laminate)>
In the production of the polarizing film, both the adhesives to be used in the production of the polarizing film without adding the compound having the nitroxy radical or the nitroxide group represented by the general formula (9) to the cleaning bath are represented by the general formula ( The nitroxy radical shown in 10) or the compound having a nitroxide group is added so that the weight ratio with the polyvinyl alcohol resin is 4:3, so as not to affect the curing reaction of the adhesive. Or the same procedure as in Example 1 except that potassium hydroxide was added to the compound having a nitroxide group in a molar ratio of 1:1 to adjust the pH (neutralize). Then, a polarizing film, a polarizing film, and a pseudo image display device (laminate) were produced. The single transmittance of the polarizing film was 40.0%.

<Example 4>
<Production of polarizing film, polarizing film, pseudo image display device (laminate)>
In the production of the polarizing film, acetoacetyl was used as both adhesives used in the production of the polarizing film without adding the compound having the nitroxy radical or the nitroxide group represented by the general formula (9) to the washing bath. Except that an aqueous solution containing a polyvinyl alcohol resin containing a group, methylolmelamine, and a compound having a nitroxy radical represented by the general formula (9) or a nitroxide group in a weight ratio of 7:2:1 was used. By the same operation as in Example 1, a polarizing film, a polarizing film, and a pseudo image display device (laminate) were produced. The single transmittance of the polarizing film was 39.7%.

<Example 5>
<Production of polarizing film, polarizing film, pseudo image display device (laminate)>
In the production of the polarizing film, as both adhesives used, 40 parts by weight of N-hydroxyethylacrylamide (HEAA), 60 parts by weight of acryloylmorpholine (ACMO), and 3 parts by weight of a photoinitiator “IRGACURE 819” (manufactured by BASF). Are mixed to prepare an adhesive, which is applied onto a polarizing film so that the thickness of the adhesive layer after curing is 1.0 μm, and is irradiated with ultraviolet rays as active energy rays to cure the adhesive to obtain a polarizing film. A polarizing film, a polarizing film, and a pseudo image display device (laminate) were produced by the same operation as in Example 1 except that the above was produced. Ultraviolet irradiation is performed using a gallium-encapsulated metal halide lamp, irradiation device: Fusion UV Systems, Inc. Light HAMMER 10, bulb: V bulb, peak illuminance: 1600 mW/cm ² , integrated irradiation amount 1000/mJ/cm ² (wavelength 380 to 440 nm). ), and the illuminance of ultraviolet rays was measured using a Sola-Check system manufactured by Solatell.

<Example 6>
<Production of polarizing film, polarizing film, pseudo image display device (laminate)>
As the thermoplastic resin base material, an amorphous isophthalic copolymer polyethylene terephthalate film (thickness: 100 μm) having a long shape, a water absorption rate of 0.75% and a Tg of about 75° C. was used. Corona treatment was applied to one surface of the resin substrate. Polyvinyl alcohol (polymerization degree: 4200, saponification degree: 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gosephimmer Z410") in a ratio of 9:1 100 weight of PVA-based resin To 13 parts by weight, 13 parts by weight of potassium iodide was added to prepare a PVA aqueous solution (coating solution). The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60° C. to form a PVA-based resin layer having a thickness of 13 μm, and a laminate was prepared. The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds in an oven at 130° C. (in-air auxiliary stretching treatment). Then, the laminate was immersed in an insolubilizing bath (solution of boric acid having a concentration of 4.0% by weight) having a liquid temperature of 40° C. for 30 seconds (insolubilizing treatment). Then, a dyeing bath having a liquid temperature of 30° C. (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water) was added to the finally obtained polarizing film. It was immersed for 60 seconds while adjusting the iodine concentration to be 8.11% (dyeing treatment). Next, it was immersed for 30 seconds in a crosslinking bath (aqueous solution having a potassium iodide concentration of 3.0% by weight and a boric acid concentration of 5.0% by weight) at a liquid temperature of 40° C. (crosslinking treatment). Then, while the laminate was immersed in a boric acid aqueous solution (boric acid concentration 4.0% by weight) at a liquid temperature of 70° C., the total draw ratio was 5.5 in the longitudinal direction (longitudinal direction) between rolls having different peripheral speeds. Uniaxial stretching was performed so as to double the length (underwater stretching treatment). Then, the laminate was immersed in a cleaning bath (potassium iodide concentration 3% by weight) at a liquid temperature of 30° C. (cleaning treatment). Then, while being dried in an oven kept at 90°C, it was contacted with a heating roll made of SUS whose surface temperature was kept at 75°C for about 2 seconds (drying shrinkage treatment). In this way, a polarizing film having a thickness of 5 μm was formed on the resin substrate.

Then, as an adhesive, a polyvinyl alcohol resin containing an acetoacetyl group (average polymerization degree: 1,200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 mol%) and methylolmelamine were used in a weight ratio. An aqueous solution containing 3:1 was used. Using this adhesive, a transparent protective film (thickness: 30 μm) made of a (meth)acrylic resin (modified acrylic polymer having a lactone ring structure) is formed on the surface of the polarizing film obtained above, which is opposite to the resin substrate. A film (manufactured by Nippon Shokubai Co., Ltd., moisture permeability of 125 g/(m ² ·24 h)) was bonded using a roll bonding machine. Next, the resin substrate was peeled off, and an acrylic pressure-sensitive adhesive layer containing a compound having a nitroxyl radical or a nitroxide group was transferred to the peeled surface to prepare a polarizing film with a pressure-sensitive adhesive layer. The acrylic pressure-sensitive adhesive containing a compound having a nitroxy radical or a nitroxide group has a general formula (9) as a compound having a nitroxy radical or a nitroxide group with respect to 80 parts by weight of a solid content of a solution of an acrylic polymer. Is 20 parts by weight, an isocyanate crosslinking agent (manufactured by Tosoh Corporation, trade name "Takenate D110N", trimethylolpropane/xylylene diisocyanate adduct) 0.02 parts by weight, a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-41-1056") 0.2 part by weight was compounded.

The acrylic acid monomer-free adhesive described in Example 1 was attached to the transparent protective film surface of the polarizing film with an adhesive layer, and a glass plate was attached via the adhesive layers on both sides to obtain a pseudo image display device. (Laminate) was prepared.

<Example 7>
<Production of polarizing film, polarizing film, pseudo image display device (laminate)>
Example 2 was repeated except that a nitroxy radical represented by the general formula (8) or a compound having a nitroxide group was used instead of the general formula (9) in both adhesives used in the production of the polarizing film. By the same operation as above, a polarizing film, a polarizing film, and a pseudo image display device (laminate) were produced.

<Comparative Example 1>
<Production of polarizing film, polarizing film, pseudo image display device (laminate)>
In the production of the polarizing film, the polarizing film and the polarizing film were prepared in the same manner as in Example 1 except that the washing bath was not added with the compound having the nitroxyl radical represented by the general formula (9) or the nitroxide group. A film and a pseudo image display device (laminate) were produced. The polarizing film obtained had a content of a compound having a nitroxy radical or a nitroxide group of 0% by weight and a thickness of 18 μm. The single transmittance of the polarizing film was 39.6%.

<Comparative example 2>
<Production of polarizing film, polarizing film, pseudo image display device (laminate)>
In the production of the polarizing film, the polarizing film, the polarizing film, and the pseudo image display were performed in the same manner as in Example 6 except that the acrylic adhesive was not added with a compound having a nitroxy radical or a nitroxide group. A device (laminate) was produced.

Using the above-obtained pseudo image display devices (laminates) of Examples and Comparative Examples, the above [Evaluation of simple substance transmittance under high temperature environment] and [Nitroxy radical contained in polarizing film under high temperature environment] Or the measurement of the content of the compound having a nitroxide group] was performed. The results are shown in Table 1.

10: Polarizing film 11: Polarizing film 12 and 13: Transparent protective film 20, 30, 40, and 50: Adhesive layer or adhesive layer 80: Front transparent member 90: Image display cell 100: Image display device 101: One side Protective polarizing film 102: Double-sided protective polarizing film

Claims (5)

A front transparent member, a polarizing film, and an image display cell is an image display device provided in this order via an adhesive layer or an adhesive layer,
The polarizing film has a polarizing film formed by adsorbing and orienting iodine on a polyvinyl alcohol film,
At least one of the polarizing film of the polarizing film , the pressure-sensitive adhesive layer, and the adhesive layer contains a compound having a nitroxy radical or a nitroxide group,
The polarizing film has the general formula (1): X (% by weight)>0.01.
(In the general formula (1), X is a polarizing plate in which a transparent protective film is bonded to at least one surface of the polarizing film via the adhesive layer, and a glass plate is bonded to both surfaces of the polarizing film via the adhesive layer. The combined laminated body satisfies the condition represented by the content of the compound having a nitroxy radical or a nitroxide group in the polarizing film in the laminated body left at 105° C. for 24 hours. An image display device characterized by. The image display device according to claim 1, wherein the compound having a nitroxy radical or a nitroxide group is an N-oxyl compound. The polarizing film is a single-sided protective polarizing film in which a transparent protective film is attached to at least one surface of the polarizing film via the pressure-sensitive adhesive layer or the adhesive layer. 2. The image display device according to 2. The polarizing film is a double-sided protective polarizing film in which a transparent protective film is attached to both surfaces of the polarizing film via the pressure-sensitive adhesive layer or the adhesive layer. The image display device according to claim 1. An optical layer is a laminated polarizing film in which at least one surface of the one-sided protective polarizing film or the both-sided protective polarizing film is laminated with an optical layer via the pressure-sensitive adhesive layer or the adhesive layer. The image display device according to 3 or 4.

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