CN111819617B

CN111819617B - Image display device

Info

Publication number: CN111819617B
Application number: CN201980017836.3A
Authority: CN
Inventors: 黑田拓马; 山下智弘; 泽田浩明; 高田胜则
Original assignee: Nitto Denko Corp
Current assignee: Nitto Denko Corp
Priority date: 2018-11-12
Filing date: 2019-11-12
Publication date: 2021-12-28
Anticipated expiration: 2039-11-12
Also published as: TWI828796B; JP6706399B1; JPWO2020100869A1; KR20200108079A; WO2020100869A1; CN111819260B; TW202024687A; KR20200105959A; KR102266084B1; KR20210075966A; JP2020129148A; JP2020184078A; JP6724269B1; TW202024688A; WO2020100870A1; CN111819260A; JPWO2020100870A1; CN111819617A; KR102281482B1

Abstract

The present invention provides an image display device, which is sequentially provided with a front surface transparent component, a polarizing film and an image display unit through an adhesive layer or an adhesive layer, wherein the polarizing film is provided with a polarizing film formed by adsorbing iodine to a polyvinyl alcohol film and orienting the film, at least one of the polarizing film, the adhesive layer and the adhesive layer contains a compound containing a nitroxyl radical or a nitroxyl radical, and the polarizing film satisfies the general formula (1): and X (% by weight) is > 0.01 (in the general formula (1), X represents the content of a compound having a nitroxyl radical or a nitroxyl radical in a polarizing film in a laminate obtained by laminating glass plates on both surfaces of a polarizing film, which is laminated with a transparent protective film on at least one surface of the polarizing film via an adhesive layer, after the laminate is left at 105 ℃ for 24 hours). The image display device is excellent in the effect of suppressing the decrease in the monomer transmittance due to the coloring of the polarizing film in a high-temperature environment.

Description

Image display device

Technical Field

The present invention relates to an image display device.

Background

Conventionally, as a polarizing film used for various image display devices such as a liquid crystal display device and an organic EL display device, a polyvinyl alcohol-based film subjected to dyeing treatment (containing a dichroic material such as iodine or a dichroic dye) has been used in view of having both high transmittance and high degree of polarization. The polarizing film was produced as follows: the polyvinyl alcohol film is subjected to various treatments such as swelling, dyeing, crosslinking, stretching, and the like in a bath, and then subjected to a cleaning treatment, followed by drying. The polarizing film is generally used in the form of a polarizing film (polarizing plate) in which a protective film such as triacetylcellulose is bonded to one surface or both surfaces thereof with an adhesive.

The polarizing film is used in the form of a laminated polarizing film (optical laminate) in which other optical layers are laminated as necessary, and the polarizing film or the laminated polarizing film (optical laminate) is used as the above-mentioned various image display devices by being bonded between an image display unit such as a liquid crystal cell or an organic EL element and a front surface transparent member such as a front surface transparent plate (window layer) on the viewing side or a touch panel via an adhesive layer or an adhesive layer.

In recent years, such various image display devices are used as in-vehicle image display devices such as car navigation devices and rear view monitors in addition to mobile devices such as mobile phones and tablet terminals, and their applications are expanding. Accordingly, the polarizing film and the laminated polarizing film are required to have higher durability in a more severe environment (for example, a high-temperature environment) than the conventional requirements, and a polarizing film intended to ensure such durability has been proposed (patent document 1).

In addition, it is generally known that a dye-based polarizing film using a dichroic dye such as an azo-based compound is superior in light resistance under high temperature and high humidity conditions to an iodine-based polarizing film (polarizing film formed by orienting iodine by adsorbing it to a polyvinyl alcohol-based film) (patent document 2), and it is disclosed that a hindered amine-based compound is contained in an adhesive used for a polarizing plate having the dye-based polarizing film in order to improve discoloration in a light resistance test of the polarizing plate (patent document 3).

Documents of the prior art

Patent document

Patent document 1: japanese Kohyo publication No. 2012-516468

Patent document 2: japanese patent laid-open No. 2001-240762

Patent document 3: japanese patent laid-open publication No. 2005-338343

Disclosure of Invention

Problems to be solved by the invention

On the other hand, when a polarizing film or a laminated polarizing film using an iodine-based polarizing film which is considered to have inferior light resistance under high-temperature and high-humidity conditions to a dyed polarizing film as described above is exposed to a high-temperature environment, the polarizing film is colored, and the monomer transmittance thereof is lowered. In particular, an image display device configured by laminating the above-described polarizing film or laminated polarizing film between an image display unit and a front surface transparent member with an adhesive layer or an adhesive layer interposed therebetween has a problem that the polarizing film is significantly colored and the monomer transmittance is significantly reduced.

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

Means for solving the problems

That is, the present invention relates to an image display device comprising a front surface transparent member, a polarizing film and an image display unit, which are sequentially provided with an adhesive layer or an adhesive layer therebetween, wherein the polarizing film comprises a polarizing film formed by adsorbing iodine to a polyvinyl alcohol-based film and orienting the film, at least one of the polarizing film, the adhesive layer and the adhesive layer comprises a compound having a nitroxyl radical or a nitroxyl group, and the polarizing film satisfies the general formula (1): and X (% by weight) is > 0.01 (in the general formula (1), X represents the content of a compound having a nitroxyl radical or a nitroxyl radical in a polarizing film in a laminate obtained by laminating glass plates on both surfaces of a polarizing film, which is laminated with a transparent protective film on at least one surface of the polarizing film via an adhesive layer, after the laminate is left at 105 ℃ for 24 hours).

ADVANTAGEOUS EFFECTS OF INVENTION

The details of the mechanism of action of the effect of the image display device of the present invention are not clear, but are presumed as follows. However, the present invention may be explained without being limited to this mechanism of action.

The image display device of the present invention is provided with a front surface transparent member, a polarizing film, and an image display unit in this order with an adhesive layer or an adhesive layer interposed therebetween, wherein at least one of the polarizing film, the adhesive layer, and the adhesive layer contains a compound having a nitroxyl radical or a nitroxyl group. The polarizing film includes an iodine-based polarizing film formed by adsorbing iodine to a polyvinyl alcohol-based film and orienting the film. As described in patent documents 2 and 3, the iodine-based polarizing film is generally considered to have inferior durability such as heat resistance compared with a dye-based polarizing film, and the reason for this is presumably because iodine contained in the polarizing film promotes polyene formation caused by a dehydration reaction of polyvinyl alcohol in a high-temperature environment.

On the other hand, it is presumed that, when the compound having a nitroxyl radical or a nitroxyl group contained in at least one of the polarizing film, the adhesive layer, and the adhesive layer of the present invention is exposed to a high-temperature environment, the compound moves (stays) in the image display device together with moisture present in the image display device (moisture present in the adhesive layer, and the like), and therefore, a part of the compound having a nitroxyl radical or a nitroxyl group permeates the iodine-based polarizing film. As a result, it is presumed that the compound having a nitroxyl radical or a nitroxyl group in the polarizing film can efficiently capture radicals generated in the polyene formation reaction described above in a high-temperature environment, and therefore, the image display device of the present invention can suppress a decrease in the monomer transmittance due to coloring of the polarizing film.

Drawings

Fig. 1 is a schematic cross-sectional view showing one embodiment of an image display device.

Fig. 2 is a schematic cross-sectional view showing one mode of a single-sided protective polarizing film.

Fig. 3 is a schematic cross-sectional view showing one mode of a double-sided protective polarizing film.

Description of the symbols

10: polarizing film

11: polarizing film

12 and 13: transparent protective film

20. 30, 40 and 50: adhesive or adhesive layer

80: front surface transparent member

90: image display unit

100: image display device

101: single-sided protective polarizing film

102: double-sided protective polarizing film

Detailed Description

Fig. 1 is a schematic cross-sectional view showing one embodiment of an image display device of the present invention. In the image display device 100 of fig. 1, the front surface transparent member 80 is bonded to the polarizing film 10 via the adhesive layer or adhesive layer 20, and the image display unit 90 is bonded to the polarizing film 10 via the adhesive layer or adhesive layer 30.

Fig. 2 is a schematic cross-sectional view showing one embodiment 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 a polarizing film 10 in which a polarizing film 11 and a transparent protective film 13 are laminated via an adhesive layer or an adhesive layer 50.

Fig. 3 is a schematic cross-sectional view showing one embodiment of the double-sided protective polarizing film of the present invention. The double-sided protective polarizing film 102 of fig. 3 shows one embodiment of the polarizing film 10 in which the polarizing film 11 and the transparent protective film 13 are bonded to each other with the adhesive layer or the adhesive layer 50 interposed therebetween, and the polarizing film 11 and the transparent protective film 12 are bonded to each other with the adhesive layer or the adhesive layer 40 interposed therebetween.

The image display device of the present invention is provided with a front surface transparent member, a polarizing film, and an image display unit in this order with an adhesive layer or an adhesive layer interposed therebetween, wherein at least one of the polarizing film, the adhesive layer, and the adhesive layer contains a compound having a nitroxyl radical or a nitroxyl group. The compounds having a nitroxyl radical or a nitroxyl group may be used alone or in combination of two or more.

The compound having a nitroxyl radical or nitroxyl group may be an N-oxyl compound (having C-N (-C) -O) in view of having a relatively stable radical at room temperature in air^·Compound (O) as a functional group^·Oxygen radical)), a known compound can be used. Examples of the N-oxyl compound include compounds having an organic group having the following structure.

[ chemical formula 1]

(in the general formula (1), R¹Represents an oxygen radical, R²～R⁵Independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, n represents 0 or 1), and the left side of the dotted line portion in the general formula (1) represents an arbitrary organic group.

Examples of the compound having an organic group include compounds represented by the following general formulae (2) to (5).

[ chemical formula 2]

(in the general formula (2), R¹～R⁵And n is as defined above, R⁶Represents a hydrogen atom, or an alkyl group, an acyl group or an aryl group having 1 to 10 carbon atoms, and n represents 0 or 1. )

[ chemical formula 3]

(in the general formula (3), R¹～R⁵And n is as defined above,R⁷and R⁸Independently represents a hydrogen atom, or an alkyl group, an acyl group or an aryl group having 1 to 10 carbon atoms. )

[ chemical formula 4]

(in the general formula (4), R¹～R⁵And n is as defined above, R⁹～R¹¹Independently represents a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, an acyl group, an amino group, an alkoxy group, a hydroxyl group, or an aryl group. )

[ chemical formula 5]

(in the general formula (5), R¹～R⁵And n is as defined above, R¹²Represents a hydrogen atom, or an alkyl group, amino group, alkoxy group, hydroxyl group, or aryl group having 1 to 10 carbon atoms. )

In the above general formulae (1) to (5), R is R from the viewpoint of easy acquisition²～R⁵Preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms. In the general formula (2), R is R from the viewpoint of easy acquisition⁶Preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and more preferably a hydrogen atom. In the general formula (3), R is preferably R from the viewpoint of easy acquisition⁷And R⁸Independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, more preferably a hydrogen atom. In the general formula (4), R is R from the viewpoint of easy acquisition⁹～R¹¹Preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. In the general formula (5), R is R from the viewpoint of easy acquisition¹²Preferably hydroxyl, amino or alkoxy. In the general formulae (1) to (5), n is preferably 1 from the viewpoint of easy acquisition.

Further, examples of the N-oxyl compound include: n-oxyl compounds described in, for example, Japanese patent application laid-open Nos. 2003-64022, 11-222462, 2002-284737 and 2016/047655.

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

[ chemical formula 6]

(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.)

[ chemical formula 7]

[ chemical formula 8]

The molecular weight of the compound having a nitroxyl radical or nitroxyl group is preferably 1000 or less, more preferably 500 or less, and still more preferably 300 or less, from the viewpoint of efficiently capturing radicals generated in the polyene formation reaction.

< polarizing film >

The polarizing film of the present invention has a polarizing film formed by adsorbing iodine to a polyvinyl alcohol film and orienting the film.

The polyvinyl alcohol (PVA) film may be one having a light-transmitting property in a visible light region and obtained by dispersing and adsorbing iodine, without any particular limitation. The PVA film used in the roll film generally 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 film include polyvinyl alcohol and derivatives thereof. Examples of the derivative of the polyvinyl alcohol include: polyvinyl formal, polyvinyl acetal; olefins such as ethylene and propylene; and derivatives obtained by modification with unsaturated carboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, and alkyl esters thereof, acrylamide, and the like. The polyvinyl alcohol preferably has an average polymerization degree of about 100 to 10000, more preferably about 1000 to 10000, and further preferably about 1500 to 4500. The saponification degree of the polyvinyl alcohol is preferably about 80 to 100 mol%, more preferably about 95 to 99.95 mol%. The average polymerization degree and the saponification degree can be determined according to JIS K6726.

The polyvinyl alcohol film may contain additives such as a plasticizer and a surfactant. Examples of the plasticizer include: glycerin, diglycerin, triglycerol, ethylene glycol, propylene glycol, polyethylene glycol, and the like, polyhydric alcohols and condensates thereof, and the like. The amount of the above-mentioned additive is not particularly limited, and is preferably about 20% by weight or less in the polyvinyl alcohol film, for example.

The content of iodine in the polarizing film is preferably 1 wt% or more and 15 wt% or less. The content of 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 discoloration in a durability test, and is preferably 12% by weight or less, more preferably 10% by weight or less, from the viewpoint of preventing polyalkyleneoxide formation.

In the case where the polarizing film contains the compound having a nitroxyl radical or a nitroxyl group, the content of the compound having a nitroxyl radical or a nitroxyl group is preferably 20% by weight or less. The content of the compound having a nitroxyl radical or nitroxyl group is preferably 0.005% by weight or more, more preferably 0.01% by weight or more, even more preferably 0.1% by weight or more, and is preferably 15% by weight or less, more preferably 12% by weight or less, even more preferably 10% by weight or less, from the viewpoint of suppressing a decrease in the monomer transmittance due to coloring of the polarizing film in a high-temperature environment.

< method for producing polarizing film >

The method for producing a polarizing film includes: the polarizing film is obtained by subjecting the polyvinyl alcohol-based film to at least a dyeing step, a crosslinking step, and a stretching step, optionally followed by a swelling step and a washing step. In the case where the polarizing film contains the compound having a nitroxyl radical or a nitroxyl group, the treatment bath in any one or more of the treatment steps of the swelling step, the cleaning step, the dyeing step, the crosslinking step, and the stretching step may contain the compound having a nitroxyl radical or a nitroxyl group. The content of the compound having a nitroxyl radical or a nitroxyl group and the content of the iodine contained in the polarizing film can be controlled by the concentration of the compound having a nitroxyl radical or a nitroxyl group and the concentrations of iodine, potassium iodide, and the like contained in any one of the treatment baths in the swelling step, the dyeing step, the crosslinking step, the stretching step, and the cleaning step, based on the treatment temperature and the treatment time of each treatment bath. In particular, when the cleaning step is performed after the dyeing step, the crosslinking step, and the stretching step are performed, the content of the compound having a nitroxyl radical or a nitroxyl group and the content of the iodine can be easily adjusted to desired ranges in view of allowing a component such as a compound having a nitroxyl radical or a nitroxyl group or iodine to be eluted from or adsorbed to the polyvinyl alcohol film in the cleaning step in consideration of the treatment conditions in the dyeing step, the crosslinking step, the stretching step, and the like.

In addition, additives such as zinc salt, pH adjuster, pH buffer, and other salts may be contained in each treatment bath in the swelling step, the dyeing step, the crosslinking step, the stretching step, and the washing step. 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 inorganic weak 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 salts of alkali metals and alkaline earth metals.

The concentration of the compound having a nitroxyl radical or a nitroxyl group contained in any of the treatment baths is not generally determined because of the influence of the number of treatments, treatment time, treatment temperature, and the like of each treatment, but is usually preferably 0.01% by weight or more, more preferably 0.05% by weight or more, further preferably 0.1% by weight or more, and further preferably 30% by weight or less, more preferably 25% by weight or less, and further preferably 20% by weight or less, from the viewpoint of efficiently controlling the content of the compound having a nitroxyl radical or a nitroxyl group in the polarizing film.

The swelling step is a treatment step of immersing the polyvinyl alcohol-based film in a swelling bath, and can remove dirt, an anti-blocking agent, and the like on the surface of the polyvinyl alcohol-based film, and can suppress uneven dyeing by swelling the polyvinyl alcohol-based film. The swelling bath generally uses a medium containing water as a main component, such as water, distilled water, or pure water. The swelling bath may be added with a surfactant, an alcohol, or the like as appropriate according to a conventional method.

The temperature of the swelling bath is preferably about 10 to 60 ℃, more preferably about 15 to 45 ℃, and further preferably about 18 to 30 ℃. The immersion time in the swelling bath is not generally determined because the swelling degree of the polyvinyl alcohol-based film is affected by the temperature of the swelling bath, and is preferably about 5 to 300 seconds, more preferably about 10 to 200 seconds, and still more preferably about 20 to 100 seconds. The swelling step may be performed only 1 time, or may be performed a plurality of times as needed.

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 to the polyvinyl alcohol-based film to orient the film. The iodine solution is preferably an aqueous iodine solution, and more preferably contains iodine and an iodide as a dissolution aid. The iodide includes potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, and the like. Among these, potassium iodide is preferable from the viewpoint of controlling the potassium content in the polarizing film.

The concentration of iodine in the dyeing bath is preferably about 0.01 to 1 wt%, more preferably about 0.02 to 0.5 wt%. The concentration of the iodide in the dyeing bath is preferably about 0.01 to 20 wt%, more preferably about 0.05 to 10 wt%, and still more preferably about 0.1 to 5 wt%.

The temperature of the dyeing bath is preferably about 10 to 50 ℃, more preferably about 15 to 45 ℃, and further preferably about 18 to 35 ℃. The immersion time in the dyeing bath is not generally determined because the degree of dyeing of the polyvinyl alcohol-based film is affected by the temperature of the dyeing bath, and is preferably about 10 to 300 seconds, and more preferably about 20 to 240 seconds. The dyeing step may be performed only 1 time, or may be performed a plurality of times as needed.

The crosslinking step is a treatment step of immersing the polyvinyl alcohol film in a treatment bath (crosslinking bath) containing a boron compound, and the polyvinyl alcohol film can be crosslinked by the boron compound to adsorb iodine molecules or dye molecules to the crosslinked structure. Examples of the boron compound include: boric acid, borates, borax, and the like. The crosslinking bath is generally an aqueous solution, and may be, for example, a mixed solution of an organic solvent miscible with water and water. In addition, from the viewpoint of controlling the potassium content in the polarizing film, the crosslinking bath may contain potassium iodide.

The concentration of the boron compound in the crosslinking bath is preferably about 1 to 15 wt%, more preferably about 1.5 to 10 wt%, and still more preferably about 2 to 5 wt%. 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, more preferably about 1.5 to 10% by weight, and still more preferably about 2 to 5% by weight.

The temperature of the crosslinking bath is preferably about 20 to 70 ℃, and more preferably about 30 to 60 ℃. The immersion time in the crosslinking bath is not generally determined because the degree of crosslinking of the polyvinyl alcohol-based film is affected by the temperature of the crosslinking bath, and is preferably about 5 to 300 seconds, and more preferably about 10 to 200 seconds. The crosslinking step may be performed only 1 time, or may be performed a plurality of times as needed.

The stretching step is a treatment step of stretching the polyvinyl alcohol-based film in at least one direction at a predetermined magnification. In general, a polyvinyl alcohol-based film is uniaxially stretched in the transport direction (longitudinal direction). The method of stretching is not particularly limited, and any of wet stretching and dry stretching may be employed. The stretching step may be performed only 1 time, or may be performed a plurality of times as needed. The stretching step may be performed at any stage in the production of the polarizing film.

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

The temperature of the stretching bath is preferably about 25 to 80 ℃, more preferably about 40 to 75 ℃, and still more preferably about 50 to 70 ℃. The immersion time in the stretching bath is not generally determined because the degree of stretching of the polyvinyl alcohol-based film is affected by the temperature of the stretching bath, and is preferably about 10 to 800 seconds, and more preferably about 30 to 500 seconds. The stretching treatment in the wet stretching method may be performed together with any 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: an inter-roll stretching method, a heated roll stretching method, a compression stretching method, and the like. The dry drawing method may be performed together with the drying step.

The total stretching ratio (cumulative stretching ratio) of the polyvinyl alcohol-based film may be set as appropriate according to the purpose, and is preferably about 2 to 7 times, more preferably about 3 to 6.8 times, and still more preferably about 3.5 to 6.5 times.

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

The temperature of the cleaning bath is preferably about 5 to 50 ℃, more preferably about 10 to 40 ℃, and further preferably about 15 to 30 ℃. The immersion time in the cleaning bath is not generally determined because the degree of cleaning of the polyvinyl alcohol-based film is affected by the temperature of the cleaning bath, and is preferably about 1 to 100 seconds, more preferably about 2 to 50 seconds, and still more preferably about 3 to 20 seconds. The swelling step may be performed only 1 time, or may be performed a plurality of times as needed.

The method for producing a polarizing film may further include a drying step. The drying step is a step of drying the polyvinyl alcohol-based film cleaned in the cleaning step to obtain a polarizing film, and the polarizing film having a desired moisture content can be obtained by drying. The drying is carried out by any suitable method, and examples thereof include: natural drying, air-blowing drying, heating drying.

The drying temperature is preferably about 20 to 150 ℃, and more preferably about 25 to 100 ℃. The drying time is not generally determined because the degree of drying of the polarizing film is affected by the drying temperature, and is preferably about 30 to 600 seconds, and more preferably about 60 to 300 seconds. The drying step may be performed only 1 time, or may be performed a plurality of times as needed.

The thickness of the polarizing film is preferably 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, a laminate including a polyvinyl alcohol resin layer formed on a resin substrate such as a thermoplastic resin can be used as a method for producing a thin polarizing film having a thickness of less than that of the polyvinyl alcohol film.

< method for producing polarizing film (thin polarizing film) >

The method for producing a polarizing film (thin polarizing film) includes: a step of forming a polyvinyl alcohol resin layer containing a polyvinyl alcohol resin on one side of a long thermoplastic resin base material to prepare a laminate; the polarizing film is obtained by subjecting the laminate to an optional insolubilization treatment step, a crosslinking treatment step, and a cleaning treatment step while conveying the laminate in the longitudinal direction, and at least to an auxiliary stretching treatment step in a gas atmosphere, a dyeing treatment step, and an in-aqueous-solution stretching treatment step. In the case where the polarizing film contains the compound having a nitroxyl radical or a nitroxyl group, the treatment bath in any one or more of the insolubilization treatment step, the crosslinking treatment step, the washing treatment step, the dyeing treatment step, and the stretching treatment step in an aqueous solution may contain the compound having a nitroxyl radical or a nitroxyl group. The content of the compound having a nitroxyl radical or a nitroxyl group and the content of the iodine contained in the polarizing film can be controlled by the concentration of the compound having a nitroxyl radical or a nitroxyl group and the concentrations of iodine, potassium iodide, and the like contained in any of the treatment baths in the insolubilization treatment step, the crosslinking treatment step, the washing treatment step, the dyeing treatment step, and the stretching treatment step in an aqueous solution, and the treatment temperature and the treatment time for each treatment bath. In particular, when the cleaning treatment step is performed, the content of the compound having a nitroxyl radical or a nitroxyl group and the content of iodine can be easily adjusted to desired ranges in view of the fact that a component such as a compound having a nitroxyl radical or a nitroxyl group or iodine can be eluted from or adsorbed to the polyvinyl alcohol film in consideration of the treatment conditions in the dyeing treatment step, the stretching treatment step in an aqueous solution, and the like in the cleaning treatment step.

The concentration of the compound having a nitroxyl radical or a nitroxyl group contained in any of the treatment baths is not generally determined because of the influence of the number of treatments, treatment time, treatment temperature, and the like of each treatment, and is usually preferably 0.01% by weight or more, more preferably 0.05% by weight or more, further preferably 0.1% by weight or more, and further preferably 30% by weight or less, more preferably 25% by weight or less, and further preferably 20% by weight or less, from the viewpoint of efficiently controlling the content of the compound having a nitroxyl radical or a nitroxyl group in the polarizing film.

< Process for preparing laminate >

As a method for producing the laminate, any suitable method can be adopted, and examples thereof include: a method of applying a coating solution containing the polyvinyl alcohol resin (PVA-based resin) on the surface of the thermoplastic resin substrate and drying the coating solution. The thickness of the thermoplastic resin substrate is preferably about 20 to 300 μm, and more preferably about 50 to 200 μm. The thickness of the PVA based resin layer is preferably about 3 to 40 μm, and more preferably about 3 to 20 μm.

The thermoplastic resin base absorbs water to greatly reduce the tensile stress, and the water absorption rate is preferably about 0.2% or more, more preferably about 0.3% or more, from the viewpoint of enabling stretching at a high rate. On the other hand, the water absorption rate of the thermoplastic resin substrate is preferably about 3% or less, more preferably about 1% or less, from the viewpoint of preventing a defect such as deterioration in appearance of the polarizing film obtained due to a significant decrease in dimensional stability of the thermoplastic resin substrate. The water absorption can be adjusted by, for example, introducing a modifying group into the constituent material of the thermoplastic resin substrate. The water absorption is a value determined in accordance with JIS K7209.

The glass transition temperature (Tg) of the thermoplastic resin substrate is preferably about 120 ℃ or lower from the viewpoint of suppressing crystallization of the PVA-based resin layer and sufficiently ensuring stretchability of the laminate. In view of plasticization of the thermoplastic resin substrate with water and favorable stretching in an aqueous solution, the glass transition temperature (Tg) is preferably about 100 ℃ or lower, and more preferably about 90 ℃ or lower. On the other hand, the glass transition temperature of the thermoplastic resin substrate is preferably about 60 ℃ or higher from the viewpoint of preventing defects such as deformation of the thermoplastic resin substrate when the coating liquid is applied and dried and producing a good laminate. The glass transition temperature can be adjusted by, for example, introducing a modifying group into the constituent material of the thermoplastic resin substrate and heating the resultant with a crystallizing material. The glass transition temperature (Tg) is a value determined in accordance with JIS K7121.

As the constituent material of the thermoplastic resin substrate, any suitable thermoplastic resin can be used. Examples of the thermoplastic resin include: ester resins such as polyethylene terephthalate resins, cycloolefin resins such as norbornene resins, olefin resins such as polypropylene resins, polyamide resins, polycarbonate resins, and copolymer resins thereof. Among these, norbornene-based resins and amorphous (non-crystalline) polyethylene terephthalate-based resins are preferable, and amorphous (non-crystalline) polyethylene terephthalate-based resins are preferably used from the viewpoint that the thermoplastic resin substrate is very excellent in stretchability and can be inhibited from crystallizing during stretching. Examples of the amorphous (noncrystalline) polyethylene terephthalate resin include a copolymer containing isophthalic acid and/or cyclohexanedicarboxylic acid as a dicarboxylic acid, and a copolymer containing cyclohexanedimethanol and diethylene glycol as a diol.

The thermoplastic resin substrate may be subjected to a surface treatment (e.g., corona treatment) before the PVA-based resin layer is formed, or an easy-adhesion layer may be formed on the thermoplastic resin substrate. By performing such treatment, the adhesion between the thermoplastic resin substrate and the PVA-based resin layer can be improved. The thermoplastic resin substrate may be stretched before the PVA-based resin layer is formed.

The coating liquid is a solution obtained by dissolving a PVA-based resin in a solvent. Examples of the solvent include: water, dimethyl sulfoxide, dimethylformamide, dimethylacetamide, N-methylpyrrolidone, various glycols, polyhydric alcohols such as trimethylolpropane, and amines such as ethylenediamine and diethylenetriamine, and water is preferred. These solvents may be used alone, or two or more kinds may be used in combination. The concentration of the PVA-based resin in the coating solution is preferably about 3 to 20 parts by weight per 100 parts by weight of the solvent, from the viewpoint of forming a uniform coating film which adheres to the thermoplastic resin substrate.

From the viewpoint of improving the orientation of the polyvinyl alcohol molecules by stretching, it is preferable to add a halide to the coating liquid. As the halide, any suitable halide can be used, and examples thereof include iodide, sodium chloride, and the like. Examples of the iodide include: potassium iodide, sodium iodide, lithium iodide, etc., with potassium iodide being preferred. 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.

Further, an additive may be added to the coating liquid. Examples of the additives include: plasticizers such as ethylene glycol and glycerin; and surfactants such as nonionic surfactants.

As a method for applying the coating liquid, any suitable method can be adopted, and examples thereof include: roll coating, spin coating, wire bar coating, dip coating, die coating, curtain coating, spray coating, and blade coating (comma coating, etc.). The drying temperature of the coating liquid is preferably about 50 ℃.

< auxiliary stretching Process in gas atmosphere >

In the auxiliary stretching step in the gas atmosphere, the laminate may be stretched at a high stretch ratio so that the thermoplastic resin substrate can be stretched while crystallization thereof is suppressed. The stretching method for assisting the stretching step in the gas atmosphere may be fixed-end stretching (for example, a method of stretching using a tenter) or free-end stretching (for example, a method of uniaxially stretching a laminate by passing the laminate between rolls having different peripheral speeds), and the free-end stretching is preferable from the viewpoint of obtaining high optical characteristics.

The stretching ratio in the auxiliary stretching step in the gas atmosphere is preferably about 2 to 3.5 times. The auxiliary stretching treatment in the gas atmosphere may be performed in one stage or in multiple stages. In the case of performing in multiple stages, the stretching magnification is the product of the stretching magnifications in each stage.

The stretching temperature in the auxiliary stretching step in the gas atmosphere may be set to any suitable value depending on the material for forming the thermoplastic resin substrate, the stretching method, and the like, and is preferably, for example, not lower than the glass transition temperature (Tg) of the thermoplastic resin substrate, more preferably not lower than the glass transition temperature (Tg) +10 ℃, and still more preferably not lower than the glass transition temperature (Tg) +15 ℃. On the other hand, the upper limit of the stretching temperature is preferably about 170 ℃ from the viewpoint of suppressing rapid progress of crystallization of the PVA type resin and suppressing defects caused by crystallization (for example, inhibiting orientation of the PVA type resin layer by stretching).

< procedure of insolubilization >

If necessary, the insolubilization treatment step may be performed after the auxiliary stretching treatment step in the gas atmosphere and before the dyeing treatment step and the stretching treatment step in an aqueous solution. The insolubilization step is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing the insolubilization step, water resistance can be imparted to the PVA-based resin layer, and the PVA can be prevented from being degraded in orientation when immersed in water. The concentration of the boric acid aqueous solution is preferably about 1 to 5 parts by weight relative to 100 parts by weight of water. The liquid temperature of the insolubilization treatment bath is preferably about 20 to 50 ℃.

< dyeing Process >

The dyeing step is performed by dyeing the PVA-based resin layer with iodine. Examples of the adsorption method include: a method of immersing a PVA-based resin layer (laminate) in a dyeing solution containing iodine; a method of applying the dyeing liquid to a PVA-based resin layer; a method of spraying the dyeing solution on the PVA-based resin layer, and the like, a method of immersing the PVA-based resin layer (laminate) in the dyeing solution containing iodine is preferable.

The amount of iodine in the dyeing bath is preferably about 0.05 to 0.5 parts by weight based on 100 parts by weight of water. In order to increase the solubility of iodine in water, it is preferable to add the iodide to an aqueous iodine solution. The amount of the iodide 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. In order to suppress the dissolution of the PVA based resin, the liquid temperature of the dyeing bath is preferably about 20 to 50 ℃. From the viewpoint of ensuring the transmittance of the PVA-based resin layer, the immersion time is preferably about 5 seconds to 5 minutes, and more preferably about 30 seconds to 90 seconds. From the viewpoint of obtaining a polarizing film having good optical characteristics, the ratio of the contents of iodine and iodide in the iodine aqueous solution is preferably about 1:5 to 1:20, and more preferably about 1:5 to 1: 10.

< Cross-linking treatment Process >

If necessary, the crosslinking treatment step may be performed after the dyeing treatment step and before the stretching treatment step in an aqueous solution. The crosslinking treatment step is typically performed by immersing the PVA-based resin layer in an aqueous boric acid solution. By performing the crosslinking treatment step, water resistance can be imparted to the PVA-based resin layer, and the orientation of the PVA can be prevented from being lowered when the PVA is immersed in high-temperature water during subsequent stretching in an aqueous solution. The boric acid concentration of the aqueous boric acid solution is preferably about 1 to 5 parts by weight relative to 100 parts by weight of water. In addition, when the crosslinking treatment step is performed, it is preferable to further mix the iodide in the crosslinking bath. The iodine compound can suppress elution of iodine adsorbed on the PVA-based resin layer. The amount of the iodide is preferably about 1 to 5 parts by weight based on 100 parts by weight of water. The liquid temperature of the crosslinking bath (aqueous boric acid solution) is preferably about 20 to 50 ℃.

< Process of stretching in aqueous solution >

The step of stretching in an aqueous solution is performed by immersing the laminate in a stretching bath. In the step of stretching in an aqueous solution, the stretching can be performed at a temperature lower than the glass transition temperature (typically, about 80 ℃) of the thermoplastic resin substrate or the PVA type resin layer, and the stretching can be performed at a high magnification while suppressing crystallization of the PVA type resin layer. The stretching method in the aqueous solution stretching step may be fixed-end stretching (for example, a method of stretching using a tenter) or free-end stretching (for example, a method of uniaxially stretching a laminate by passing the laminate between rolls having different peripheral speeds), and the free-end stretching is preferable from the viewpoint of obtaining high optical characteristics.

The step of stretching in an aqueous solution is preferably performed by immersing the laminate in an aqueous solution of boric acid (stretching in an aqueous solution of boric acid). By using an aqueous boric acid solution as a stretching bath, the PVA-based resin layer can be provided with rigidity capable of withstanding the tension applied during stretching and water resistance insoluble in water. The boric acid concentration of the aqueous boric acid solution is preferably 1 to 10 parts by weight, more preferably 2.5 to 6 parts by weight, based on 100 parts by weight of water. In addition, an iodide may be added to the stretching bath (aqueous boric acid solution). The liquid temperature of the stretching bath is preferably about 40 to 85 ℃, and more preferably about 60 to 75 ℃. The immersion time of the laminate in the stretching bath is preferably about 15 seconds to 5 minutes.

The stretching ratio in the stretching step in the aqueous solution is preferably about 1.5 times or more, and more preferably about 3 times or more.

The total stretch ratio of the laminate is preferably about 5 times or more, and more preferably about 5.5 times or more, with respect to the original length of the laminate.

< cleaning treatment Process >

Preferably, the step of stretching in an aqueous solution is followed by a step of cleaning. The cleaning treatment step is typically performed by immersing the PVA-based resin layer in an aqueous potassium iodide solution.

In addition, additives such as zinc salt, pH adjuster, pH buffer, and other salts may be contained in each treatment bath in the dyeing treatment step, the stretching treatment step in aqueous solution, the insolubilizing treatment step, the crosslinking treatment step, and the washing treatment step. 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 inorganic weak 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 salts of alkali metals and alkaline earth metals.

< adhesive layer >

As the adhesive for forming the adhesive layer of the present invention, various adhesives used for polarizing films can be applied, and examples thereof include: rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, urethane-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinyl pyrrolidone-based adhesives, polyacrylic amide-based adhesives, cellulose-based adhesives, and the like. Among these, acrylic adhesives are preferred. The acrylic adhesive contains an acrylic polymer as a base polymer, and examples thereof include: an acrylic adhesive disclosed in Japanese patent laid-open publication No. 2017 and 75998.

The acrylic polymer in the acrylic pressure-sensitive adhesive is a polymer having a main skeleton of a monomer unit of an alkyl (meth) acrylate. The alkyl (meth) acrylate preferably has an alkyl group having 1 to 20 carbon atoms, and the content of the alkyl (meth) acrylate is preferably 40% by weight or more, more preferably 60% by weight or more, based on the total amount of the monomer components constituting the base polymer. In addition, from the viewpoint of adjusting the adhesiveness of the adhesive, a monomer unit such as a nitrogen-containing monomer unit or a hydroxyl group-containing monomer may be contained. In addition, in order to form a crosslinked structure in the pressure-sensitive adhesive layer, a crosslinking agent may also be used, and as the crosslinking agent, for example: a crosslinking agent generally used such as an isocyanate-based crosslinking agent, an epoxy-based crosslinking agent, an oxazoline-based crosslinking agent, an aziridine-based crosslinking agent, a carbodiimide-based crosslinking agent, or a metal chelate-based crosslinking agent. The amount of the crosslinking agent used is usually 10 parts by weight or less, preferably 5 parts by weight or less, relative to 100 parts by weight of the base polymer.

A silane coupling agent may be added to the binder in order to adjust the adhesive strength; tackifiers such as terpene tackifiers, styrene tackifiers, phenol tackifiers, rosin tackifiers and epoxy tackifiers. In addition, an ultraviolet absorber may be added from the viewpoint of improving light resistance. In addition to the components exemplified above, additives such as a plasticizer, a softening agent, a deterioration preventing agent, a filler, a colorant, an antioxidant, a surfactant, and an antistatic agent may be used in the adhesive within a range in which the properties of the adhesive are not impaired.

As a method of forming the adhesive layer, for example: a method in which the adhesive is applied to a separator or the like subjected to a peeling treatment, dried to form an adhesive layer, and then transferred to a polarizing film or the like; or a method in which the adhesive is applied to a polarizing film or the like and dried to form an adhesive layer. The thickness of the adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm, preferably about 2 to 50 μm.

< adhesive layer >

As the adhesive forming the adhesive layer of the present invention, various adhesives used for polarizing films can be applied, and examples thereof include: isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latexes, water-based polyesters, and the like. These adhesives are generally used in the form of an adhesive (aqueous adhesive) formed from an aqueous solution, and contain 0.5 to 60 wt% of a solid content. Among these, polyvinyl alcohol adhesives are preferred, and acetoacetyl group-containing polyvinyl alcohol adhesives are more preferred.

The aqueous adhesive may contain a crosslinking agent. As the crosslinking agent, a compound having at least 2 functional groups reactive with a component such as a polymer constituting the adhesive in 1 molecule can be usually used, and examples thereof include: alkylene diamines; isocyanates; epoxy resin; aldehydes; amino-formaldehydes such as methylol urea and methylol melamine. The amount of the crosslinking agent in the adhesive is usually about 10 to 60 parts by weight per 100 parts by weight of the components such as the polymer constituting the adhesive.

The adhesive may be an active energy ray-curable adhesive such as an ultraviolet-curable adhesive or an electron beam-curable adhesive, in addition to the above. Examples of the active energy ray-curable adhesive include (meth) acrylate adhesives. Examples of the curable component in the (meth) acrylate adhesive include: a compound having a (meth) acryloyl group, a compound having a vinyl group. Examples of the compound having a (meth) acryloyl group include: alkyl (meth) acrylates such as C1-20 chain alkyl (meth) acrylates, alicyclic alkyl (meth) acrylates, and polycyclic alkyl (meth) acrylates; a hydroxyl group-containing (meth) acrylate; epoxy group-containing (meth) acrylates such as glycidyl (meth) acrylate, and the like. The (meth) acrylate-based adhesive may contain a nitrogen-containing monomer such as hydroxyethyl (meth) acrylamide, N-methylol (meth) acrylamide, N-methoxymethyl (meth) acrylamide, N-ethoxymethyl (meth) acrylamide, or (meth) acryloylmorpholine. The (meth) acrylic adhesive may contain tripropylene glycol diacrylate, 1, 9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane formal acrylate, and ditrimethylolpropane formal acrylate

A polyfunctional monomer such as alkylene glycol diacrylate or EO-modified diglycerol tetraacrylate as a crosslinking component. Further, as the cationic polymerization curing adhesive, a compound having an epoxy group or an oxetane group may be used. The compound having an epoxy group is not particularly limited as long as it has at least 2 epoxy groups in the molecule, and various curable epoxy compounds generally known 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, bonding accelerators such as ethylene oxide, ultraviolet absorbers, deterioration prevention agents, dyes, processing aids, ion trapping agents, antioxidants, tackifiers, fillers, plasticizers, leveling agents, foaming inhibitors, antistatic agents, heat-resistant stabilizers, hydrolysis-resistant stabilizers and the like.

The adhesive may be applied to either the transparent protective film side (or the functional layer side) described later or the polarizing film side, or to both sides. After the bonding, a drying step is performed to form an adhesive layer formed by applying a dry layer. After the drying step, ultraviolet rays and electron beams may be irradiated as necessary. The thickness of the adhesive layer is not particularly limited, and is preferably about 30 to 5000nm, more preferably about 100 to 1000nm when an aqueous adhesive or the like is used, and is preferably about 0.1 to 100 μm, more preferably about 0.5 to 10 μm when an ultraviolet-curable adhesive, an electron beam-curable adhesive or the like is used.

In the case where the pressure-sensitive adhesive layer or the adhesive layer contains the compound having a nitroxyl radical or a nitroxyl group, the content of the compound having a nitroxyl radical or a nitroxyl group in the pressure-sensitive adhesive layer or the adhesive layer is preferably 1% by weight or more, more preferably 5% by weight or more, further preferably 10% by weight or more, and preferably 70% by weight or less, more preferably 50% by weight or less, from the viewpoint of suppressing a decrease in the monomer transmittance due to coloring of the polarizing film in a high-temperature environment.

< Single-sided protective polarizing film and double-sided protective polarizing film >

In the single-sided protective polarizing film of the present invention, a transparent protective film is bonded to at least one surface of the polarizing film with the pressure-sensitive adhesive layer or the adhesive layer interposed therebetween. In the double-sided protective polarizing film of the present invention, transparent protective films are bonded to both sides of the polarizing film with the pressure-sensitive adhesive layer or the adhesive layer interposed therebetween.

The transparent protective film is not particularly limited, and various transparent protective films used for polarizing films can be used. As materials constituting the transparent protective film, for example: a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy and the like. Examples of the thermoplastic resin include: cellulose ester resins such as cellulose triacetate, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins such as nylon and aromatic polyamide, polyimide resins, polyolefin resins such as polyethylene, polypropylene and ethylene-propylene copolymers, (meth) acrylic resins, cyclic polyolefin resins having a cyclic or norbornene structure (norbornene resins), polyacrylic resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The transparent protective film may be a cured layer formed of a thermosetting resin or an ultraviolet-curable resin such as a (meth) acrylic resin, a urethane resin, an acrylic urethane resin, an epoxy resin, or a silicone resin. Among these, cellulose ester resins, polycarbonate resins, (meth) acrylic resins, cyclic polyolefin resins, and polyester resins are preferable.

The thickness of the transparent protective film may be suitably determined, and is generally preferably about 1 to 500 μm, more preferably about 1 to 300 μm, and still more preferably about 5 to 100 μm from the viewpoints of strength, handling properties such as handling properties, and thin layer properties.

The transparent protective film has a nitroxyl radical or nitroxylThe water-permeable compound preferably has a water vapor permeability of 50 g/(m) from the viewpoint of easily permeating the water-permeable compound into the polarizing film, because the compound moves (stays) together with water present in the image display device (water present in the pressure-sensitive adhesive layer, the adhesive layer, and the like) in the image display device²24h or more, more preferably 100 g/(m)²24h) or more, and more preferably 200 g/(m)²24h) above. The moisture permeability can be calculated by placing a sample cut into a diameter of 60mm in a moisture permeable cup containing about 15g of calcium chloride, placing the sample in a thermostatic apparatus at a temperature of 40 ℃ and a humidity of 90% r.h. and measuring the weight increase of calcium chloride before and after the sample is left to stand for 24 hours, based on the moisture permeability test (cup method) of JIS Z0208.

When the transparent protective films are bonded to both surfaces of the polarizing film, the transparent protective films may be the same or different.

The transparent protective film may be a retardation plate having a front retardation of 40nm or more and/or a thickness direction retardation of 80nm or more. The front retardation is usually controlled to be in the range of 40 to 200nm, and the thickness direction retardation is usually controlled to be 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, and therefore, the thickness can be reduced.

Examples of the phase difference plate include: birefringent films obtained by subjecting a polymer material to uniaxial or biaxial stretching treatment, alignment films of liquid crystal polymers, retardation plates obtained by supporting alignment layers of liquid crystal polymers with films, and the like. The thickness of the retardation plate is not particularly limited, and is usually about 20 to 150 μm. The phase plate may be used by bonding the phase plate to a transparent protective film having no retardation.

The transparent protective film may contain any suitable additive such as an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, a coloring inhibitor, a flame retardant, an antistatic agent, a pigment, and a colorant. 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 adhesion prevention layer, a diffusion layer, or an antiglare layer may be provided on the surface of the transparent protective film which is not bonded to the polarizing film. The functional layers such as the hard coat layer, the antireflection layer, the adhesion prevention layer, the diffusion layer, and the antiglare layer may be provided as the protective film itself, or may be provided separately from the protective film.

The polarizing film and the transparent protective film, or the polarizing film and the functional layer are generally bonded together through the 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 a surface modification treatment layer, an adhesive layer, a barrier layer, a refractive index adjustment layer, or the like.

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

Examples of the easy adhesive agent for forming the easy adhesive layer include: the material for forming the resin composition includes various resins having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, silicones, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, and the like. The easy-adhesion layer may be provided in advance on a protective film, and the easy-adhesion layer side of the protective film may be laminated on the polarizing film with the adhesive layer or the adhesive layer interposed therebetween.

The barrier layer is a layer having a function of preventing impurities such as oligomers and ions eluted from the transparent protective film from migrating (penetrating) into the polarizing film. The barrier layer may be any layer that has transparency and can prevent impurities from eluting from a transparent protective film or the like, and examples of materials for forming the barrier layer include: urethane prepolymer-based forming materials, cyanoacrylate-based forming materials, epoxy-based forming materials, and the like.

The refractive index adjustment layer is provided to suppress a decrease in transmittance due to reflection between the transparent protective film and the polarizing film or other layers having different refractive indices. Examples of the refractive index adjusting material for forming the refractive index adjusting layer include: the composition contains various resins containing silica, acrylic acid-styrene, melamine and the like, and additives.

The polarizing film of the present invention satisfies the general formula (1) from the viewpoint of suppressing a decrease in monomer transmittance caused by coloring of the polarizing film in a high-temperature environment: and X (% by weight) is > 0.01 (in the general formula (1), X represents the content of the compound having a nitroxyl radical or a nitroxyl group in a polarizing film in a laminate obtained by laminating glass plates on both surfaces of a polarizing film through the adhesive layer after the laminate is left at 105 ℃ for 24 hours, and a transparent protective film is laminated on at least one surface of the polarizing film through the adhesive layer). X (wt%) is preferably 0.02 or more, and more preferably 0.05 or more.

< laminated polarizing film >

In the laminated polarizing film (optical laminate) of the present invention, an optical layer is bonded to at least one surface of the single-sided protective polarizing film or the double-sided protective polarizing film with the pressure-sensitive adhesive layer or the adhesive layer interposed therebetween.

In the laminated polarizing film (optical laminate) of the present invention, the polarizing film is bonded to an optical layer. The optical layer is not particularly limited, and optical layers that are used in the formation of liquid crystal displays and the like in some cases, such as 1-layer or 2-layer or more reflective plates, semi-transmissive plates, retardation plates (including wave plates such as 1/2 and 1/4), and optical compensation films, can be used. The laminated polarizing film may be, in particular, a reflective polarizing film or a semi-transmissive polarizing film in which a reflective plate or a semi-transmissive reflective plate is further laminated on the polarizing film, an elliptical polarizing film or a circular polarizing film in which a phase difference plate is further laminated on the polarizing film, a wide-viewing-angle polarizing film in which a viewing angle compensation film is further laminated on the polarizing film, or a polarizing film in which a brightness enhancement film is further laminated on the polarizing film.

The pressure-sensitive adhesive layer or the adhesive layer may be provided in advance on one surface or both surfaces of the single-sided protective polarizing film, the double-sided protective polarizing film, or the laminated polarizing film in order to bond an image display unit such as a liquid crystal cell or an organic EL element to another member such as a front-side transparent plate on the viewing side or a front-side transparent member such as a touch panel. The material having the pressure-sensitive adhesive layer provided on at least one surface of the polarizing film or the laminated polarizing film in this manner is referred to as 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-attached laminated polarizing film.

The exposed surface of the pressure-sensitive adhesive layer or the adhesive layer is preferably covered by a temporary adhesive film for the purpose of preventing contamination or the like until the pressure-sensitive adhesive layer or the adhesive layer is actually used. This can prevent the adhesive layer or the adhesive layer from being contaminated in a normal handling state. As the separator, for example, a separator obtained by coating an appropriate thin layer body such as a plastic film, a rubber sheet, paper, cloth, nonwoven fabric, net, foamed sheet, metal foil, or a laminate thereof with an appropriate release agent such as silicone, long-chain alkyl, fluorine, or molybdenum sulfide, as necessary, can be used.

< front surface transparent Member >

The front surface transparent member of the present invention is a front surface transparent member disposed on the visible side of the image display unit. Examples of the front surface transparent member include: a front surface transparent plate (window layer), a touch panel, and the like. As the front surface transparent plate, a front surface transparent plate having appropriate mechanical strength and thickness can be used. As such a transparent plate, for example, a transparent resin plate such as an acrylic resin or a polycarbonate resin, a glass plate, or the like can be used. As the touch panel, for example, various touch panels of a resistive film type, a capacitive type, an optical type, an ultrasonic type, and the like, a glass plate having a touch sensor function, a transparent resin plate, and the like can be used. In the case of using a capacitive touch panel as the front transparent member, a front transparent plate made of glass or a transparent resin plate is preferably provided on the side closer to the visible side than the touch panel.

< image display Unit >

Examples of the image display unit of the present invention include: liquid crystal cells, organic EL cells, and the like. As the liquid crystal cell, any of a reflective liquid crystal cell using external light, a transmissive liquid crystal cell using light from a light source such as a backlight, and a transflective liquid crystal cell using both light from the outside and light from the light source can be used, for example. In the case where the liquid crystal cell uses light from a light source, the image display device (liquid crystal display device) is also provided with a polarizing film on the side opposite to the viewing side of the image display cell (liquid crystal cell) and a light source. The polarizing film on the light source side and the liquid crystal cell are preferably bonded together with an appropriate adhesive layer interposed therebetween. Examples of the driving method of the liquid crystal cell include: VA mode, IPS mode, TN mode, STN mode, bend (bend) orientation (pi-type), and the like.

As the organic EL unit, for example, an organic EL unit in which a transparent electrode, an organic light-emitting layer, and a metal electrode are sequentially stacked on a transparent substrate to form a light-emitting body (organic electroluminescent light-emitting body) can be suitably used. The organic light-emitting layer is a laminate of various organic thin films, and various layer structures including, for example: a laminate of a hole injection layer made of triphenylamine derivative or the like and a light-emitting layer made of a fluorescent organic solid such as anthracene, a laminate of these light-emitting layers and an electron injection layer made of perylene derivative or the like, a laminate of a hole injection layer, a light-emitting layer, and an electron injection layer, and the like.

Examples

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

< example 1 >

< preparation of polarizing film >

A polyvinyl alcohol film having an average polymerization degree of 2400, a saponification degree of 99.9 mol% and a thickness of 45 μm was prepared. The polyvinyl alcohol film was immersed between rolls having different peripheral speed ratios for 30 seconds in a swelling bath (water bath) at 20 ℃ to swell the film and stretched 2.2 times in the transport direction (swelling step), and then immersed for 30 seconds in a dyeing bath (aqueous iodine solution prepared by blending iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at 30 ℃ so that the concentration of iodine in the finally obtained polarizing film was 4.47% by weight, and stretched 3.3 times in the transport direction (dyeing step) based on the original polyvinyl alcohol film (polyvinyl alcohol film which was not stretched at all in the transport direction) while adjusting the concentration and dyeing the film so that the concentration of iodine in the polarizing film was adjusted for 30 seconds. Next, the dyed polyvinyl alcohol film was immersed in a crosslinking bath (aqueous solution having a boric acid concentration of 3.0 wt% and a potassium iodide concentration of 3.0 wt%) at 40 ℃ for 28 seconds, and the original polyvinyl alcohol film was stretched 3.6 times in the transport direction (crosslinking step). Further, the obtained polyvinyl alcohol film was immersed in a stretching bath (an aqueous solution having a boric acid concentration of 4.0 wt% and a potassium iodide concentration of 5.0 wt%) at 61 ℃ for 60 seconds, stretched 6.0 times in the transport direction based on the original polyvinyl alcohol film (stretching step), and then immersed in a cleaning bath (an aqueous solution having a potassium iodide concentration of 2.0 wt% and a concentration of a compound having a nitroxyl radical or a nitroxyl group represented by the following general formula (9)) at 35 ℃ for 10 seconds (cleaning step). The washed polyvinyl alcohol film was dried at 40 ℃ for 30 seconds to prepare a polarizing film. The content of the compound having a nitroxyl radical or nitroxyl group in the polarizing film was 0.28% by weight as determined by the following measurement method, and the thickness of the polarizing film was 18 μm.

[ chemical formula 9]

[ method for measuring the content (% by weight) of a compound having a nitroxyl radical or nitroxyl group in a polarizing film ]

About 20mg of the polarizing film was collected and quantified, and the polarizing film was dissolved in 1mL of water under heating, and then diluted with 4.5mL of methanol, and the obtained extract was filtered through a membrane filter, and the concentration of a compound having a nitroxyl radical or a nitroxyl group was measured on the filtrate by HPLC (ACQUITY UPLC H-class Bio, manufactured by Waters).

[ method for measuring iodine content (% by weight) in polarizing film ]

The iodine concentration (% by weight) of the polarizing film was determined by the following equation using a fluorescent X-ray analyzer (product of Shigaku corporation, trade name: ZSX-PRIMUS IV, measurement diameter: 20 mm).

Iodine concentration (wt%): 14.474 × (fluorescent X-ray intensity)/(film thickness) (kcps/. mu.m)

The coefficient for calculating the concentration differs depending on the measurement device, but the coefficient can be obtained by using an appropriate calibration curve.

< production of polarizing film >

As the adhesive, an aqueous solution containing a polyvinyl alcohol resin having an acetoacetyl group (average polymerization degree of 1200, saponification degree of 98.5 mol%, acetoacetylation degree of 5 mol%) and methylolmelamine at a weight ratio of 3:1 was used. Using this adhesive, a cellulose triacetate film having a thickness of 47 μm (moisture permeability of 342 g/(m) having a hard coat layer as a transparent protective film was bonded to both sides of the polarizing film obtained above by a roll laminator²24 hours), manufactured by konica minolta, trade name "KC 4 UYW"), and then dried by heating in an oven (temperature 60 ℃ for 4 minutes), to prepare a polarizing film having transparent protective films attached to both surfaces of the polarizing film. The monomer 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 placed in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet tube and a condenser. Further, 0.1 part by weight of 2, 2' -azobisisobutyronitrile as a polymerization initiator was added together with 100 parts by weight of ethyl acetate per 100 parts by weight of the monomer mixture (solid content), nitrogen gas was introduced while slowly stirring, and after nitrogen substitution, the liquid temperature in the flask was kept near 55 ℃ to conduct polymerization for 8 hours, thereby preparing a solution of an acrylic polymer having a weight average molecular weight (Mw) of 180 ten thousand. Then, 0.02 parts by weight of an isocyanate crosslinking agent (trade name "Takenate D110N", manufactured by Tosoh corporation, trimethylolpropane/xylylene diisocyanate adduct) and 0.2 parts by weight of a silane coupling agent (trade name "X-41-1056", manufactured by shin-Etsu chemical Co., Ltd.) were added to 100 parts by weight of the solid content of the obtained acrylic polymer solution to prepare an acrylic pressure-sensitive adhesive composition solution. Next, the solution of the acrylic pressure-sensitive adhesive composition obtained above was applied to one surface of a polyethylene terephthalate film (mitsubishi chemical polyester film, product name "MRF 38", separator) treated with a silicone-based release agent so that the thickness of the pressure-sensitive adhesive layer after drying became 20 μm, and the pressure-sensitive adhesive layer was formed on the surface of the separator by drying at 90 ℃ for 1 minute. Next, the pressure-sensitive adhesive layer formed on the separator was transferred to one surface of the polarizing film thus produced, thereby producing a polarizing film with a pressure-sensitive adhesive layer.

< production of analog image display device (laminate) >

The protective polarizing film with the pressure-sensitive adhesive layer obtained above was cut into a size of 40 × 40mm so that the absorption axis of the polarizing film became a long side, and a glass plate (analog image display unit) was bonded to the other surface of the polarizing film through the pressure-sensitive adhesive layer, and another glass plate (analog front surface transparent member) was bonded to the other surface of the polarizing film through an acrylic-free monomer pressure-sensitive adhesive (trade name "lucicacs CS 9868", manufactured by ritonac corporation) having a thickness of 200 μm, to prepare an analog image display device (laminate).

[ evaluation of monomer transmittance in high-temperature Environment ]

The analog image display device (laminate) obtained above was left to stand in a hot air oven at a temperature of 105 ℃ for 48 hours, and the monomer transmittance (Δ Ts) before and after charging (heating) was measured. The monomer transmittance was measured by a spectrophotometer (product name "DOT-3" manufactured by murakamura color technology research institute, inc.) and evaluated based on the following criteria. The monomer transmittance is a Y value obtained by correcting visibility with a 2-degree field of view (C light source) of JlS Z8701-. The measurement wavelength is 380 to 700nm (per 10 nm). The results are shown in Table 1.

ΔTs(％)＝Ts₄₈－Ts₀

Wherein, Ts₀The monomer transmittance, Ts, of the analog image display device (laminate) before heating₄₈The monomer transmittance of the simulated image display device (laminate) after heating for 48 hours was shown.

○：5≥ΔTs(％)≥0

X: Δ Ts (%) > 5, or Δ Ts (%) < 0

The Δ Ts (%) is preferably 5. gtoreq.DELTA.Ts (%). gtoreq.0, and more preferably 4. gtoreq.DELTA.Ts (%). gtoreq.0.

[ measurement of the content of a compound having a nitroxyl radical or nitroxyl group contained in a polarizing film in a high-temperature environment ]

The obtained simulated image display device (laminate) was left to stand in a hot air oven at a temperature of 105 ℃ for 24 hours, and the content of the compound having a nitroxyl radical or nitroxyl group contained in the polarizing film after charging (heating) was determined by the following method. The heated analog image display device was immersed in about 1000mL of a solution of dichloromethane or toluene for 3 days or more to dissolve the protective film, and the polarizing film was taken out, whereby about 40mg of the polarizing film was obtained. After the above polarizing film was washed with pure dichloromethane or toluene, about 1mg of the polarizing film was collected and quantified, and the polarizing film was dissolved in 0.5mL of water under heating, and then diluted with 1mL of methanol, and the resulting extract was filtered through a membrane filter, and the concentration of a compound having a nitroxyl radical or a nitroxyl group was measured on the filtrate by using LCMS (UltiMate 3000/LTQ orbitrap XL, manufactured by Thermo Fisher Scientific).

< example 2 >

< production of polarizing film, and analog image display device (laminate) >

A polarizing film, and a pseudo-image display device (laminate) were produced in the same manner as in example 1, except that the compound having a nitroxyl radical or a nitroxyl group represented by the general formula (9) was not added to the cleaning bath in the production of the polarizing film, and the compound having a nitroxyl radical or a nitroxyl group represented by the general formula (9) was added to the two adhesives used in the production of the polarizing film so that the weight ratio to the polyvinyl alcohol resin was 4: 3. The monomer transmittance of the polarizing film was 39.7%.

< example 3 >

< production of polarizing film, and analog image display device (laminate) >

A polarizing film, and a pseudo-image display device (laminate) were produced in the same manner as in example 1, except that the compound having a nitroxyl radical or a nitroxyl group represented by general formula (9) was not added to the cleaning bath, the compound having a nitroxyl radical or a nitroxyl group represented by general formula (10) was added to the two adhesives used in the production of the polarizing film so that the weight ratio of the compound to the polyvinyl alcohol resin was 4:3, potassium hydroxide was added so that the molar ratio of the compound having a nitroxyl radical or a nitroxyl group to the compound having a nitroxyl radical or a nitroxyl group was 1:1 without affecting the curing reaction of the adhesives, and the pH was adjusted (neutralized). The monomer transmittance of the polarizing film was 40.0%.

[ chemical formula 10]

< example 4 >

< production of polarizing film, and analog image display device (laminate) >

A polarizing film, and a pseudo-image display device (laminate) were produced in the same manner as in example 1, except that the compound having a nitroxyl radical or a nitroxyl group represented by general formula (9) was not added to the cleaning bath, and an aqueous solution containing a polyvinyl alcohol resin containing an acetoacetyl group, methylolmelamine, and the compound having a nitroxyl radical or a nitroxyl group represented by general formula (9) at a weight ratio of 7:2:1 was used as the two adhesives used in the production of the polarizing film. The monomer transmittance of the polarizing film was 39.7%.

< example 5 >

< production of polarizing film, and analog image display device (laminate) >

In the production of the polarizing film, as two kinds of adhesives used, 40 parts by weight of N-hydroxyethyl acrylamide (HEAA), 60 parts by weight of acryloyl morpholine (ACMO), and a photoinitiator "IRGACURE 819"Polarizing films, and analog image display devices (laminates) were produced in the same manner as in example 1, except that 3 parts by weight of the mixture (manufactured by BASF) was used to prepare an adhesive, the adhesive was applied to a polarizing film so that the thickness of the cured adhesive layer became 1.0 μm, and the adhesive was cured by irradiation with ultraviolet rays as active energy rays to produce a polarizing film. The ultraviolet irradiation was performed using a gallium-sealed metal halide lamp and an irradiation apparatus: light HAMMER10 manufactured by Fusion UV Systems, Inc, valve: v valve, peak illuminance: 1600mW/cm²Cumulative dose of radiation 1000/mJ/cm²(wavelength 380 to 440nm) and the illuminance of ultraviolet light were measured by using Sola-Check system manufactured by Solatell corporation.

< example 6 >

< production of polarizing film, and analog image display device (laminate) >

As the thermoplastic resin substrate, a long-sized amorphous isophthalic acid copolymerized polyethylene terephthalate film (thickness: 100 μm) having a water absorption of 0.75% and a Tg of about 75 ℃ was used. One side of the resin substrate was subjected to corona treatment. To 100 parts by weight of a PVA resin obtained by mixing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetoacetyl-modified PVA (trade name "GOHSEFIMER Z410" available from Nippon synthetic chemical Co., Ltd.) at a ratio of 9:1, 13 parts by weight of potassium iodide was added to prepare an aqueous PVA solution (coating solution). The aqueous PVA solution was applied to the corona-treated surface of the resin substrate, and dried at 60 ℃ to form a PVA-based resin layer having a thickness of 13 μm, thereby producing a laminate. The resultant laminate was stretched in a longitudinal direction (longitudinal direction) in a unidirectional manner at the free end by a factor of 2.4 in an oven at 130 ℃ between rolls having different peripheral speeds (auxiliary stretching treatment in a gas atmosphere). Next, the laminate was immersed in an insolubilization bath (aqueous solution having a boric acid concentration of 4.0 wt%) at a liquid temperature of 40 ℃ for 30 seconds (insolubilization treatment). Next, the polarizing film was immersed in a dyeing bath (aqueous iodine solution prepared by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by weight of water) at a liquid temperature of 30 ℃ for 60 seconds while adjusting the concentration so that the iodine concentration of the finally obtained polarizing film became 8.11% (dyeing treatment). Subsequently, the substrate was immersed in a crosslinking bath (aqueous solution having a potassium iodide concentration of 3.0 wt% and a boric acid concentration of 5.0 wt%) at a liquid temperature of 40 ℃ for 30 seconds (crosslinking treatment). Then, while immersing the laminate in an aqueous boric acid solution (boric acid concentration 4.0 wt%) having a liquid temperature of 70 ℃, uniaxial stretching was performed between rollers having different peripheral speeds in the longitudinal direction (longitudinal direction) so that the total stretching ratio became 5.5 times (stretching treatment in an aqueous solution). Then, the laminate was immersed in a cleaning bath (potassium iodide concentration 3 wt.) at a liquid temperature of 30 ℃. Then, while drying in an oven maintained at 90 ℃, the sheet was contacted with a SUS heating roll maintained at a surface temperature of 75 ℃ for about 2 seconds (drying shrinkage treatment). Thus, a polarizing film having a thickness of 5 μm was formed on the resin substrate.

Then, as the adhesive, an aqueous solution containing a polyvinyl alcohol resin having an acetoacetyl group (average polymerization degree of 1200, saponification degree of 98.5 mol%, acetoacetylation degree of 5 mol%) and methylolmelamine at a weight ratio of 3:1 was used. A transparent protective film (made of a Japanese catalyst and having a moisture permeability of 125 g/(m) was applied to the surface of the polarizing film obtained above, which was opposite to the resin substrate, and was formed of a (meth) acrylic resin (a modified acrylic polymer having a lactone ring structure) and having a thickness of 30 μm using the adhesive by a roll laminator²24 h)). Next, the resin substrate was peeled off, and the acrylic pressure-sensitive adhesive layer containing the compound having a nitroxyl radical or a nitroxyl group was transferred to the peeled surface, thereby producing a polarizing film with a pressure-sensitive adhesive layer. An acrylic adhesive containing a compound having a nitroxyl radical or a nitroxyl group was prepared by mixing 20 parts by weight of the general formula (9) which is a compound having a nitroxyl radical or a nitroxyl group, 0.02 part by weight of an isocyanate crosslinking agent (product name "Takenate D110N" manufactured by Tosoh corporation, trimethylolpropane/xylylene diisocyanate adduct) and 0.2 part by weight of a silane coupling agent (product name "X-41-1056" manufactured by shin-Etsu chemical Co., Ltd.) with respect to 80 parts by weight of the solid content of the acrylic polymer solution.

The acrylic monomer-free adhesive described in example 1 was bonded to the transparent protective film surface of the above polarizing film with an adhesive layer, and glass plates were bonded via the adhesive layers on both sides to produce a pseudo image display device (laminate).

< example 7 >

< production of polarizing film, and analog image display device (laminate) >

A polarizing film, and a pseudo-image display device (laminate) were produced in the same manner as in example 2, except that the compound having a nitroxyl radical or a nitroxyl group represented by general formula (8) was used instead of the compound represented by general formula (9) for the two adhesives used in the production of the polarizing film.

< comparative example 1 >

< production of polarizing film, and analog image display device (laminate) >

A polarizing film, and a pseudo-image display device (laminate) were produced in the same manner as in example 1, except that the compound having a nitroxyl radical or a nitroxyl group represented by general formula (9) was not added to the cleaning bath in the production of the polarizing film. The polarizing film obtained had a content of the compound having a nitroxyl radical or nitroxyl group of 0% by weight and a thickness of 18 μm. The monomer transmittance of the polarizing film was 39.6%.

< comparative example 2 >

< polarizing film production of analog image display device (laminate)

A polarizing film, and a pseudo image display device (laminate) were produced in the same manner as in example 6, except that a compound having a nitroxyl radical or a nitroxyl group was not added to the acrylic adhesive in the production of the polarizing film.

The results of the evaluation of the transmittance of the monomer in the high-temperature environment and the measurement of the content of the compound having a nitroxyl radical or a nitroxyl group contained in the polarizing film in the high-temperature environment were carried out using the simulated image display devices (laminates) of the examples and comparative examples obtained above, and are shown in table 1.

Claims

1. An image display device comprising a front surface transparent member, a polarizing film, and an image display unit arranged in this order with an adhesive layer or an adhesive layer interposed therebetween,

the polarizing film has a polarizing film formed by adsorbing iodine to a polyvinyl alcohol film and orienting the film,

at least one of the polarizing film, the adhesive layer, and the adhesive layer of the polarizing film contains a compound having a nitroxyl radical or a nitroxyl group,

the polarizing film satisfies general formula (1): the condition that X (wt%) > 0.01,

in the general formula (1), X represents the content of a compound having a nitroxyl radical or a nitroxyl radical in a polarizing film in a laminate obtained by laminating glass plates on both surfaces of a polarizing film through the adhesive layer after the laminate is left at 105 ℃ for 24 hours, wherein the polarizing film is laminated with a transparent protective film on at least one surface of the polarizing film through the adhesive layer.

2. The image display apparatus according to claim 1,

the compound having a nitroxyl radical or nitroxyl group is an N-oxyl compound.

3. The image display apparatus according to claim 1 or 2,

the polarizing film is a single-sided protective polarizing film having a transparent protective film bonded to at least one surface of the polarizing film with the adhesive layer or the adhesive layer interposed therebetween.

4. The image display apparatus according to claim 1 or 2,

the polarizing film is a double-sided protective polarizing film having transparent protective films bonded to both sides of the polarizing film with the adhesive layer or the adhesive layer interposed therebetween.

5. The image display device according to claim 3, wherein an optical layer is bonded to at least one surface of the single-sided protective polarizing film with the pressure-sensitive adhesive layer or the adhesive layer interposed therebetween.

6. The image display device according to claim 4, wherein an optical layer is bonded to at least one surface of the double-sided protective polarizing film with the pressure-sensitive adhesive layer or the adhesive layer interposed therebetween.