KR102266082B1 - Polarizing film, laminated polarizing film, image display panel, and image display device - Google Patents

Abstract

A polarizing film in which a transparent protective film is bonded to at least one side of a polarizing film through an adhesive layer, wherein the polarizing film is formed by adsorption orientation of iodine on a polyvinyl alcohol-based film, and the adhesive layer is nitroxy radical or nitroxide compounds having a group. The said polarizing film is excellent in the inhibitory effect of the single transmittance fall by coloring of a polarizing film in a high temperature environment.

Description

Polarizing film, laminated polarizing film, image display panel, and image display device

The present invention relates to a polarizing film, a laminated polarizing film, an image display panel, and an image display device.

Conventionally, as a polarizing film used for various image display devices such as a liquid crystal display device and an organic EL display device, it is dyed from the viewpoint of having high transmittance and high polarization (contains dichroic substances such as iodine and dichroic dyes) A) A polyvinyl alcohol-based film is used. The said polarizing film is manufactured by performing each process, such as swelling, dyeing|staining, crosslinking, and extending|stretching, in a bath in a bath, performing washing process, and then drying the said polarizing film. Moreover, the said polarizing film is normally used as a polarizing film (polarizing plate) by which protective films, such as a triacetyl cellulose, were bonded together on the single side|surface or both surfaces using the adhesive agent.

The polarizing film is used as a laminated polarizing film (optical laminate) by laminating other optical layers as needed, and the polarizing film or the laminated polarizing film (optical laminate) is combined with an image display cell such as a liquid crystal cell or an organic EL element , it is bonded through an adhesive layer or an adhesive layer between front transparent members, such as a front transparent plate (window layer) and a touch panel, on the visual recognition side, and is used as said various image display apparatuses.

In recent years, such various image display devices are being used as in-vehicle image display devices such as vehicle navigation devices and back monitors in addition to mobile devices such as mobile phones and tablet terminals. Accordingly, the polarizing film or the laminated polarizing film is required to have high durability in a harsher environment (eg, under a high temperature environment) than has been conventionally required, and to ensure such durability A polarizing film for the purpose of this is proposed (patent document 1).

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

Japanese Patent Publication No. 2012-516468 Japanese Patent Laid-Open No. 2001-240762 Japanese Patent Laid-Open No. 2005-338343

On the other hand, as described above, a polarizing film or laminated polarizing film using an iodine-based polarizing film, which is considered to be inferior in light resistance under high-temperature and high-humidity conditions, than a dyed-based polarizing film, when exposed to a high-temperature environment, the polarizing film is colored Therefore, there was a problem in that the single transmittance was lowered. In particular, the image display device constituted by bonding the polarizing film or laminated polarizing film between the image display cell and the front transparent member with an adhesive layer or an adhesive layer interposed therebetween has a problem in that the coloring of the polarizing film is remarkable and the reduction in the single transmittance is remarkable. there was.

In view of the above circumstances, an object of this invention is to provide the polarizing film excellent in the inhibitory effect of the fall of the single transmittance|permeability by coloring of a polarizing film in a high-temperature environment.

Another object of the present invention is to provide a polarizing film, a laminated polarizing film, an image display panel, and an image display device that are excellent in the effect of suppressing the decrease in the single transmittance due to the coloring of the polarizing film.

That is, the present invention is a polarizing film in which a transparent protective film is bonded to at least one side of a polarizing film via an adhesive layer, wherein the polarizing film is formed by adsorbing and aligning iodine to a polyvinyl alcohol-based film, and the adhesive layer is nitroxy It relates to a polarizing film comprising a compound having a radical or a nitroxide group.

Moreover, this invention relates to the laminated polarizing film by which the said polarizing film is bonded to the optical layer.

Moreover, this invention relates to the image display panel by which the said polarizing film or the said laminated|multilayer polarizing film is bonded by the image display cell.

Moreover, this invention relates to the image display apparatus provided with a front transparent member on the polarizing film or laminated polarizing film side of the said image display panel.

Although the detail of the action mechanism of the effect in the polarizing film of this invention has an unclear part, it is estimated as follows. However, the present invention does not need to be interpreted as being limited to this mechanism of action.

In the polarizing film of the present invention, a transparent protective film is bonded to at least one surface of the polarizing film via an adhesive layer, and the adhesive layer contains a compound having a nitroxy radical or a nitroxide group. In addition, the polarizing film is formed by adsorbing and aligning iodine on a polyvinyl alcohol-based film. As described in Patent Documents 2 and 3, iodine-based polarizing films are generally considered to be inferior in durability, such as heat resistance, to dye-based polarizing films, but the reason for this is that the iodine contained in the polarizing film is higher than that of polyvinyl alcohol in a high-temperature environment. It is presumed that this is because it promotes a deterioration phenomenon called polyenization caused by dehydration reaction.

On the other hand, when the compound having a nitroxy radical or a nitroxide group contained in the adhesive layer of the present invention is exposed to a high temperature environment, a part of the compound having a nitroxy radical or a nitroxide group is eluted from the adhesive layer. It is estimated that it permeates into the iodine-based polarizing film adjacent to the adhesive layer. In particular, in the image display device in which the front transparent member, the polarizing film, and the image display cell are formed and configured in this order, the compound having a nitroxy radical or a nitroxide group contained in the adhesive layer is in a high temperature environment. Since it moves (remains) inside the image display device together with moisture present inside (moisture present in the pressure-sensitive adhesive layer or adhesive layer, etc.) when exposed to the It is estimated that it is easy to permeate into the iodine-based polarizing film. As a result, since it is estimated that the nitroxy radical in a polarizing film or the compound which has a nitroxide group can capture|acquire the radical which generate|occur|produces in the said polyenization reaction in a high-temperature environment efficiently, the polarizing film of this invention is coloring of a polarizing film. It is possible to suppress a decrease in the single transmittance caused by

<A compound having a nitroxy radical or a nitroxide group>

As a compound having a nitroxy radical or a nitroxide group of the present invention, from the viewpoint of having a relatively stable radical at room temperature and air, an N-oxyl compound (a compound having CN(-C)-O. as a functional group (O. represents an oxy radical)), and a known one can be used. As an N-oxyl compound, the compound etc. which have an organic group of the following structures are mentioned, for example. The compound which has the said nitroxy radical or a nitroxide group may be used independently and may use 2 or more types together.

(In general formula (1), R ¹ represents an oxyradical, R ² to R ⁵ independently represent a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n represents 0 or 1.) The left side of the dotted line part in General formula (1) shows arbitrary organic groups.

As a compound which has the said organic group, the compound etc. which are represented by the following general formula (2) - (5) are mentioned, for example.

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

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

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

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

In the general formulas (1) to (5), R ² to R ⁵ are preferably an alkyl group having 1 to 6 carbon atoms, more preferably an alkyl group having 1 to 3 carbon atoms, from the viewpoint of availability. Moreover, in the said General formula (2), from a viewpoint of availability ^{, it is preferable that R<6>} is a hydrogen atom or a C1-C10 alkyl group, and it is more preferable that it is a hydrogen atom. Moreover, in the said General formula (3), from a viewpoint of availability ^{, it is preferable that R<7>} and R<^8> are independently a hydrogen atom or a C1-C10 alkyl group, and it is more preferable that it is a hydrogen atom. Further, in the general formula (4), from the viewpoint of availability, R ⁹ to R ¹¹ are preferably a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. Moreover, in the said General formula (5), ^{it is preferable from a viewpoint of availability that R<12>} is a hydroxyl group, an amino group, or an alkoxy group. In the general formulas (1) to (5), n is preferably 1 from the viewpoint of availability.

Moreover, as said N-oxyl compound, Unexamined-Japanese-Patent No. 2003-64022, Unexamined-Japanese-Patent No. 11-222462, Unexamined-Japanese-Patent No. 2002-284737, International Publication No. 2016/047655, etc. are described, for example. N-oxyl compounds are mentioned.

Moreover, as a compound which has the said nitroxy radical or a nitroxide group, the following compounds etc. are mentioned, for example.

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

In addition, the molecular weight of the compound having a nitroxy radical or a nitroxide group is preferably 1000 or less, more preferably 500 or less, and 300 or less from the viewpoint of efficiently capturing radicals generated in the polyenization reaction. It is more preferable that it is the following.

<Polarizing film>

In the polarizing film of the present invention, a transparent protective film is bonded to at least one side of a polarizing film through an adhesive layer, and the polarizing film is formed by adsorbing and aligning iodine to a polyvinyl alcohol-based film, and the adhesive layer is the nitroxy compounds having a radical, or a nitroxide group.

<Polarizing film>

The polarizing film of the present invention is formed by adsorbing and aligning iodine to a polyvinyl alcohol-based film. The polyvinyl alcohol (PVA)-based film has light transmittance in a visible light region, and dispersion and adsorption of iodine may be used without particular limitation. Moreover, it is preferable that thickness is about 1-100 micrometers normally, and, as for the PVA type film used as a raw material, it is more preferable that it is about 1-50 micrometers.

Examples of the material for the polyvinyl alcohol-based film include polyvinyl alcohol or a derivative thereof. As a derivative of the said polyvinyl alcohol, For example, polyvinyl formal, polyvinyl acetal; olefins such as ethylene and propylene; Unsaturated carboxylic acids, such as acrylic acid, methacrylic acid, and a crotonic acid, the thing modified|denatured with its alkylester, acrylamide, etc. are mentioned. The polyvinyl alcohol preferably has an average degree of polymerization of about 100 to 10,000, more preferably about 1,000 to 10,000, and still more preferably about 1,500 to 4,500. Further, the polyvinyl alcohol preferably has a degree of saponification of about 80 to 100 mol%, and more preferably about 95 to 99.95 mol%. In addition, the said average degree of polymerization and the said saponification degree can be calculated|required according to JISK6726.

It is preferable that the content of the iodine in the polarizing film is 1% by weight or more and 15% by weight or less. In the polarizing film, the content of the iodine is preferably 1.5% by weight or more from the viewpoint of suppressing color loss during the durability test, more preferably 2% by weight or more, and 12% by weight or less from the viewpoint of preventing polyenization It is preferable, and it is more preferable that it is 10 weight% or less.

The polarizing film can be produced by, for example, immersing the polyvinyl alcohol-based film in an aqueous solution of iodine, dyeing it, and stretching the polyvinyl alcohol-based film to 3 to 7 times its original length. If necessary, it can also be immersed in aqueous solutions, such as boric acid and potassium iodide. If necessary, the polyvinyl alcohol-based film may be immersed in water before dyeing and washed with water. By washing the polyvinyl alcohol-based film with water, contamination and blocking agents on the surface of the polyvinyl alcohol-based film can be washed, and by swelling the polyvinyl alcohol-based film, there is also an effect of preventing unevenness such as dyeing. Stretching may be carried out after dyeing with iodine, and may be stretched while dyeing, or may be dyed with iodine after stretching. It can extend|stretch also in aqueous solutions, such as boric acid and potassium iodide, or a water bath.

It is preferable that the thickness of the said polarizing film is about 1-50 micrometers, and it is more preferable that it is about 1-25 micrometers. In particular, in order to obtain a polarizing film having a thickness of 8 μm or less, Japanese Patent Application Laid-Open No. 2009-098653, Japanese Patent Application Laid-Open No. 2012-073580, Japanese Patent Application Laid-Open No. 2013-238640, Japanese Patent No. 4691205 Specification, and Japanese Patents The method for manufacturing a thin polarizing film using a laminate including a polyvinyl alcohol-based resin layer formed on a resin substrate such as a thermoplastic resin as the polyvinyl alcohol-based film disclosed in Specification No. 4751481 and the like can be applied.

<Adhesive layer>

The adhesive layer of the present invention is formed by an adhesive. Various adhesives used for a polarizing film can be applied as said adhesive agent, For example, an isocyanate type adhesive agent, polyvinyl alcohol type adhesive agent, a gelatin type adhesive agent, vinyl type latex type, water-based polyester, etc. are mentioned. These adhesives are normally used as an adhesive agent (water-based adhesive) which consists of aqueous solution, and contains 0.5 to 60 weight% of solid content. Among these, a polyvinyl alcohol-type adhesive agent is preferable, and an acetoacetyl group containing polyvinyl alcohol-type adhesive agent is more preferable.

The water-based adhesive may contain a crosslinking agent. As said crosslinking agent, the compound which has at least 2 functional groups which has reactivity with components, such as a polymer which comprises an adhesive agent, in 1 molecule is normally used, For example, alkylenediamines; isocyanates; epoxies; aldehydes; and amino-formaldehyde such as methylol urea and methylol melamine. The blending amount of the crosslinking agent in the adhesive is usually about 10 to 60 parts by weight based on 100 parts by weight of components such as polymers constituting the adhesive.

Examples of the adhesive include active energy ray curing adhesives such as ultraviolet curing adhesives and electron beam curing adhesives in addition to the above. As said active energy ray hardening-type adhesive agent, a (meth)acrylate-type adhesive agent is mentioned, for example. As a curable component in the said (meth)acrylate-type adhesive agent, the compound which has a (meth)acryloyl group, and the compound which has a vinyl group are mentioned, for example. As a compound which has a (meth)acryloyl group, For example, C1-C20 chain alkyl (meth)acrylate, alicyclic alkyl (meth)acrylate, alkyl (meth), such as a polycyclic alkyl (meth)acrylate ) acrylates; hydroxyl group-containing (meth)acrylate; Epoxy group-containing (meth)acrylates, such as glycidyl (meth)acrylate, etc. are mentioned. The (meth)acrylate-based adhesive is hydroxyethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N-ethoxymethyl (meth)acrylamide, ( Nitrogen-containing monomers, such as meth)acrylamide and (meth)acryloylmorpholine, may be included. (meth)acrylate-based adhesives are tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylol propane formal acrylate, dioxane glycol diacrylate as a crosslinking component. Polyfunctional monomers, such as an acrylate and EO modified|denatured diglycerol tetraacrylate, may be included. Moreover, the compound which has an epoxy group or oxetanyl group can also be used as a cationic polymerization hardening-type adhesive agent. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various generally known curable epoxy compounds can be used.

The said adhesive may contain the appropriate additive as needed. Examples of the additive include coupling agents such as silane coupling agents and titanium coupling agents, adhesion promoters such as ethylene oxide, ultraviolet absorbers, deterioration inhibitors, dyes, processing aids, ion trapping agents, antioxidants, tackifiers, fillers , a plasticizer, a leveling agent, a foaming inhibitor, an antistatic agent, a heat-resistant stabilizer, a hydrolysis-resistant stabilizer, and the like.

Application|coating of the said adhesive agent may be performed to any of the transparent protective film side mentioned later (or the functional layer side mentioned later), the said polarizing film side, and may be performed to both. After bonding, a drying step is performed to form an adhesive layer composed of an applied dry layer. After the drying process, ultraviolet rays or electron beams may be irradiated as needed. The thickness of the adhesive layer is not particularly limited, and when using a water-based adhesive or the like, it is preferably about 30 to 5000 nm, more preferably about 100 to 1000 nm, and when using an ultraviolet curing adhesive, an electron beam curing adhesive, etc. It is preferable that it is about 0.1-100 micrometers, and it is more preferable that it is about 0.5-10 micrometers.

In the adhesive layer, the content of the compound having a nitroxy radical or a nitroxide group in the adhesive layer is preferably 70% by weight or less. The adhesive layer is preferably 1 wt% or more, more preferably 5 wt% or more, and 10 wt% or more in the adhesive layer from the viewpoint of suppressing a decrease in the single transmittance due to coloring of the polarizing film in a high-temperature environment. It is more preferable, and it is preferable that it is 60 weight% or less, and it is more preferable that it is 50 weight% or less.

<Transparent protective film>

The transparent protective film is not particularly limited, and various transparent protective films used for polarizing films may be used. As a material constituting the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is used. Examples of the thermoplastic resin include cellulose ester-based resins such as triacetyl cellulose, polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone-based resins, polysulfone-based resins, polycarbonate-based resins, nylon, Polyamide-based resin such as aromatic polyamide, polyimide-based resin, polyethylene, polypropylene, polyolefin-based resin such as ethylene/propylene copolymer, (meth)acrylic-based resin, cyclo- or cyclic polyolefin-based resin having a norbornene structure ( norbornene-based resins), polyarylate-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, and mixtures thereof. In addition, as the transparent protective film, a cured layer formed of a thermosetting resin such as (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone resin or UV curable resin may be used. Among these, cellulose ester-type resin, polycarbonate-type resin, (meth)acrylic-type resin, cyclic polyolefin-type resin, and polyester-type resin are suitable.

The thickness of the transparent protective film can be appropriately determined, but in general, from the viewpoints of workability such as strength and handleability, thin layer properties, etc., it is preferably about 1-500 µm, more preferably about 1-300 µm, , more preferably about 5 to 100 μm.

When bonding the said transparent protective film to both surfaces of the said polarizing film, the same thing may be sufficient as the transparent protective film of the both surfaces, and may be different.

As the transparent protective film, a retardation plate having a phase difference of 40 nm or more and/or a thickness direction retardation of 80 nm or more may be used. The front retardation is usually controlled in the range of 40 to 200 nm, and the thickness direction retardation is usually controlled in the range of 80 to 300 nm. When using a retardation plate as the said transparent protective film, since the said retardation plate also functions as a transparent protective film, thickness reduction can be aimed at.

Examples of the retardation plate include a birefringent film formed by uniaxially or biaxially stretching a polymer material, an alignment film of liquid crystal polymer, and a film in which an alignment layer of liquid crystal polymer is supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm. Moreover, you may use by bonding the said phase plate to the transparent protective film which does not have a phase difference.

The transparent protective film may contain any appropriate additives such as an ultraviolet absorber, antioxidant, lubricant, plasticizer, mold release agent, color inhibitor, flame retardant, antistatic agent, pigment, and colorant. In particular, when the transparent protective film includes an ultraviolet absorber, light resistance of the polarizing film may be improved.

Functional layers such as a hard coat layer, an anti-reflection layer, an anti-sticking layer, a diffusion layer or an anti-glare layer may be formed on the surface of the transparent protective film to which the polarizing film is not bonded. In addition, the functional layers such as the hard coat layer, the antireflection layer, the antistick layer, the diffusion layer and the antiglare layer can be formed on the protective film itself, or can be formed separately from the protective film.

In the polarizing film of the present invention, at least one surface of the polarizing film may be bonded to the transparent protective film via the adhesive layer, and the other surface (the other surface) of the polarizing film and the transparent protective film or the other surface of the polarizing film (the other side) and the said functional layer are normally joined via an adhesive layer or the said adhesive bond layer. Further, an image display cell or a front transparent member, which will be described later, may be directly bonded to the other surface (the other surface) of the polarizing film via the adhesive layer.

As the pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer, various pressure-sensitive adhesives used in polarizing films can be applied, for example, a rubber-based pressure-sensitive adhesive, an acrylic pressure-sensitive adhesive, a silicone-based pressure-sensitive adhesive, a urethane-based pressure-sensitive adhesive, a vinyl alkyl ether-based pressure-sensitive adhesive, a polyvinyl alcohol-based pressure-sensitive adhesive, polyvinyl A pyrrolidone-type adhesive, a polyacrylamide-type adhesive, a cellulose-type adhesive, etc. are mentioned. Among these, an acrylic adhesive is suitable. The said acrylic adhesive contains an acrylic polymer as a base polymer, For example, the acrylic adhesive described in Unexamined-Japanese-Patent No. 2017-75998 etc. can be illustrated.

As a method of forming the pressure-sensitive adhesive layer, for example, a method of applying the pressure-sensitive adhesive to a peeling-treated separator or the like, drying and transferring the pressure-sensitive adhesive layer to a polarizing film or the like, or applying the pressure-sensitive adhesive to a polarizing film or the like and drying the pressure-sensitive adhesive The method of forming a layer, etc. can be illustrated. The thickness in particular of the said adhesive layer is not restrict|limited, For example, it is about 1-100 micrometers, and it is preferable that it is about 2-50 micrometers.

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

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

Examples of the easily adhesive agent for forming the easily adhesive layer include various resins having a polyester skeleton, polyether skeleton, polycarbonate skeleton, polyurethane skeleton, silicone skeleton, polyamide skeleton, polyimide skeleton, polyvinyl alcohol skeleton, etc. forming materials can be mentioned. The said easily adhesive layer is normally formed in advance in a protective film, and the easily adhesive layer side of the said protective film and a polarizing film are laminated|stacked with the said adhesive layer or the said adhesive bond layer.

The blocking layer is a layer having a function to prevent impurities such as oligomers and ions eluted from the transparent protective film or the like from migrating (infiltrating) into the polarizing film. The block layer may be any layer that has transparency and can prevent impurities eluted from the transparent protective film or the like. Examples of the material for forming the block layer include a urethane prepolymer-based forming material and a cyanoacrylate-based forming material. , an epoxy-based forming material, and the like.

The refractive index adjusting layer is a layer formed to suppress a decrease in transmittance caused by reflection between layers having different refractive indices, such as the transparent protective film and the polarizing film. As a refractive index adjusting material which forms the said refractive index adjusting layer, the forming agent containing various resin and additives which have a silica type, an acryl type, an acryl-styrene type, a melamine type, etc. are mentioned, for example.

<Lamination Polarizing Film>

As for the laminated polarizing film (optical laminated body) of this invention, the said polarizing film is bonded by the optical layer. The optical layer is not particularly limited, but for example, a reflective plate, a transflective plate, a retardation plate (including a wave plate such as 1/2 or 1/4), and a liquid crystal display device such as a visual compensation film One or two or more optical layers may be used. As the laminated polarizing film, in particular, a reflective polarizing film or transflective polarizing film in which a reflecting plate or a transflective reflecting plate is laminated on the polarizing film, an elliptically polarizing film or a circularly polarizing film in which a retardation plate is further laminated on the polarizing film, the polarizing film A wide viewing angle polarizing film in which a visual compensation film is further laminated on a film, or a polarizing film in which a brightness enhancing film is further laminated on the polarizing film.

On one or both surfaces of the polarizing film or the laminated polarizing film, an image display cell such as a liquid crystal cell or an organic EL element and another member such as a front transparent member such as a front transparent plate or a touch panel on the viewing side are provided An adhesive layer for bonding may be laid. An adhesive layer is suitable as said adhesive bond layer. The pressure-sensitive adhesive for forming the pressure-sensitive adhesive layer is not particularly limited, but for example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer as the base polymer may be appropriately selected and used. can In particular, like the adhesive containing an acrylic polymer, it is excellent in optical transparency, shows moderate wettability, cohesiveness, and adhesiveness, and is excellent in weather resistance, heat resistance, etc. are used preferably.

Laying of the adhesive layer on one side or both surfaces of the said polarizing film or the said laminated|multilayer polarizing film can be performed by an appropriate method. As laying of the pressure-sensitive adhesive layer, for example, a pressure-sensitive adhesive solution is prepared, and it is directly laid on the polarizing film or the laminated polarizing film by an appropriate development method such as a casting method or a coating method, or a pressure-sensitive adhesive layer is formed on a separator Then, the method of attaching it on the said polarizing film or the said laminated polarizing film, etc. are mentioned. The thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength, etc., and is generally 1 to 500 μm, preferably 5 to 200 μm, and more preferably 10 to 100 μm. Thus, what an adhesive layer was formed in at least one surface of the said polarizing film or the said laminated polarizing film is called a polarizing film with an adhesive layer, or a laminated polarizing film with an adhesive layer.

It is preferable that a separator is temporarily attached to the exposed surface of the pressure-sensitive adhesive layer and covered for the purpose of preventing contamination of the pressure-sensitive adhesive layer until it is put into practical use. Thereby, contamination of an adhesive layer, etc. can be prevented in the normal handling state. As the separator, for example, a suitable thin leaf body such as plastic film, rubber sheet, paper, cloth, nonwoven fabric, net, foam sheet, metal foil, and laminates thereof may be used, as necessary, silicone-based, long-chain alkyl-based, fluorine-based, molybdenum sulfide, or the like. Coated with a suitable release agent of , etc. are used.

<Image display panel and image display device>

As for the image display panel of this invention, the said polarizing film or the said laminated polarizing film is pasted together by the image display cell. Moreover, the image display apparatus of this invention is equipped with a front transparent member on the polarizing film or laminated polarizing film side (viewing side) of the said image display panel.

As said image display cell, a liquid crystal cell, organic electroluminescent cell, etc. are mentioned, for example. 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, for example. You may use it. When the liquid crystal cell uses light from a light source, in the image display device (liquid crystal display device), a polarizing film is disposed on the side opposite to the viewing side of the image display cell (liquid crystal cell), and a light source is disposed. It is preferable that the polarizing film on the side of the said light source and the liquid crystal cell are bonded through an appropriate adhesive bond layer. As a driving method of the said liquid crystal cell, the thing of arbitrary types, such as a VA mode, an IPS mode, a TN mode, an STN mode, and a band orientation ((pi) type|mold), can be used, for example.

As said organic electroluminescent cell, what laminated|stacked in order a transparent electrode, an organic light emitting layer, and a metal electrode on a transparent substrate, and formed the light emitting body (organic electroluminescent light emitting body) etc. are used suitably, for example. The organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and a light emitting layer made of a fluorescent organic solid such as anthracene, or these light emitting layers and a perylene derivative, etc. Various layer configurations, such as a laminate of electron injection layers made of, or a laminate of a hole injection layer, a light emitting layer, and an electron injection layer, may be employed.

As a front transparent member arrange|positioned on the visual recognition side of the said image display cell, a front transparent plate (window layer), a touch panel, etc. are mentioned, for example. As the front transparent plate, a transparent plate having an appropriate mechanical strength and thickness is used. As such a transparent plate, a transparent resin plate or a glass plate, such as an acrylic resin or polycarbonate-type resin, etc. are used, for example. As said touch panel, various touch panels, such as a resistive film method, a capacitive method, an optical method, an ultrasonic method, a glass plate, a transparent resin board, etc. provided with a touch sensor function are used, for example. When a capacitive touch panel is used as the front transparent member, it is preferable that a front transparent plate made of glass or a transparent resin plate is formed on the viewing side more than the touch panel.

(Example)

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

<Example 1>

<Production of polarizing film>

A polyvinyl alcohol film having an average degree of polymerization of 2,400, a degree of saponification of 99.9 mol%, and a thickness of 45 µm was prepared. The polyvinyl alcohol film was immersed for 30 seconds in a swelling bath (water bath) at 20°C between rolls with different circumferential speed ratios and stretched 2.2 times in the conveying direction while swelling (swelling step), followed by a 30°C dyeing bath (water in 100 parts by weight). On the other hand, while adjusting the concentration so that the iodine concentration of the polarizing film finally obtained in an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7) becomes 3.60% by weight, immersion for 30 seconds and dyeing the original polyvinyl alcohol film (transfer It was stretched 3.3 times in the conveying direction on the basis of the polyvinyl alcohol film not stretched in the direction at all (dyeing process). Next, the dyed polyvinyl alcohol film is immersed in a crosslinking bath (aqueous solution having a boric acid concentration of 3.0% by weight and potassium iodide concentration of 3.0% by weight) at 40° C. for 28 seconds in the transport direction based on the original polyvinyl alcohol film. It was stretched to 3.6 times (crosslinking step). Further, the obtained polyvinyl alcohol film was immersed in a stretching bath at 61° C. (aqueous solution having a boric acid concentration of 4.0% by weight and potassium iodide concentration of 5.0% by weight) for 60 seconds, and 6.0 in the conveying direction based on the original polyvinyl alcohol film. After extending|stretching to double (stretching process), it immersed for 10 second in a 35 degreeC washing bath (aqueous solution whose potassium iodide concentration is 2.0 weight%) (washing process). The wash|cleaned polyvinyl alcohol film was dried at 40 degreeC for 30 second, and the polarizing film was produced. The thickness of the polarizing film was 18 µm.

[Method for Measuring Iodine Content (wt%) in Polarizing Film]

About the polarizing film, the iodine concentration (weight%) was calculated|required using the following formula using the fluorescent X-ray analyzer (Rigaku Corporation make, brand name "ZSX-PRIMUS IV", measurement diameter: ψ20 mm).

Iodine concentration (wt%) = 14.474 × (fluorescence X-ray intensity)/(film thickness) (kcps/μm) In addition, the coefficient for calculating the concentration varies depending on the measuring device, but the coefficient can be obtained using an appropriate calibration curve. can

<Production of polarizing film>

As an adhesive, a polyvinyl alcohol resin containing an acetoacetyl group (average degree of polymerization 1,200, saponification degree 98.5 mol%, acetoacetylation degree 5 mol%) and methylolmelamine and a nitroxy radical represented by the general formula (9), or An aqueous solution containing a compound having a nitroxide group in a weight ratio of 3:1:4 was used. Using this adhesive, a 47 μm-thick triacetyl cellulose film (water vapor transmission rate 342 g/(m 2 ·24 h), manufactured by Konica Minolta, trade name “KC4UYW”) having a hard coat layer as a transparent protective film on both sides of the polarizing film obtained above was applied with this adhesive. After bonding with a roll bonding machine, it was made to heat-dry (temperature 60 degreeC, time 4 minutes) in oven then, and the polarizing film by which the transparent protective film was bonded on both surfaces of a polarizing film was produced. The single transmittance of the polarizing film was 39.7%.

<Preparation of acrylic adhesive>

A monomer mixture containing 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate was put into a four-neck flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler. In addition, 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator is added to 100 parts of the monomer mixture (solid content) together with 100 parts of ethyl acetate, and nitrogen gas is introduced while gently stirring to replace nitrogen. , a polymerization reaction was performed for 8 hours while maintaining the liquid temperature in the flask at around 55°C to prepare a solution of an acrylic polymer having a weight average molecular weight (Mw) of 1.8 million. Thereafter, 0.02 parts of an isocyanate crosslinking agent (manufactured by Tosoh Corporation, trade name "Takenate D110N", trimethylolpropane/xylylene diisocyanate adduct), a silane coupling agent (Shin-Etsu Chemical) with respect to 100 parts of the solid content of the obtained acrylic polymer solution The Kogyo Co., Ltd. make, brand name "X-41-1056") 0.2 part was mix|blended, and the solution of the acrylic adhesive composition was prepared. Next, the solution of the acrylic pressure-sensitive adhesive composition obtained above was applied to one side of a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Polyester Film, trade name “MRF38”, separator film) treated with a silicone-based release agent. The thickness of the pressure-sensitive adhesive layer after drying was 20 μm. It apply|coated so that it may become possible, and it dried at 90 degreeC for 1 minute, and formed the adhesive layer on the surface of the separator film. Next, the adhesive layer formed on the separator film was transcribe|transferred to one side of the polarizing film produced above, and the polarizing film with an adhesive layer was produced.

<Production of pseudo-image display device (laminated body)>

The polarizing film with an adhesive layer obtained above is cut into a size of 45 x 40 mm so that the absorption axis of the polarizing film becomes the long side, a glass plate (pseudo image display cell) is bonded through an adhesive layer, and the other side of the polarizing film A separate glass plate (pseudo-front transparent member) was bonded to a 200 µm-thick acrylic acid monomer-free adhesive (manufactured by Nitto Denko Co., Ltd., trade name "LUCIACS CS9868") to prepare a pseudo image display device (laminate).

[Evaluation of simplex transmittance under high temperature environment]

The pseudo-image display device (laminated body) obtained above was left still in a hot-air oven with a temperature of 105 degreeC for 48 hours, and the single transmittance ((DELTA)Ts) before and behind injection|throwing-in (heating) was measured. The single transmittance was measured using a spectrophotometer (manufactured by Murakami Shikisai Kijutsu Kenkyusho Co., Ltd., product name "DOT-3"), and evaluated by the following standards. The said single transmittance is the Y value which performed the visibility correction|amendment by the 2 degree field of view (C light source) of JIS Z 8701-1982. Moreover, the measurement wavelength is 380-700 nm (every 10 nm). A result is shown in Table 1.

Δ Ts(%)=Ts ₄₈ -Ts ₀

Here, Ts ₀ is the single transmittance of the pseudo image display device (stacked body) before heating, and Ts ₄₈ is the single transmittance of the pseudo image display device (laminated body) after heating for 48 hours.

○: 5≥ΔTs(%)≥0

×: ΔTs(%)>5, or ΔTs(%)<0

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

<Example 2>

<Preparation of a polarizing film, a polarizing film, and a pseudo image display device (laminated body)>

In the production of the polarizing film, a compound having a nitroxy radical or nitroxide group represented by the general formula (10) is added to both adhesives to be used in a weight ratio of 4:3 with the polyvinyl alcohol resin, and In order not to affect the curing reaction, the same as in Example 1, except that the pH was adjusted (neutralized) by adding potassium hydroxide to a molar ratio of 1:1 with respect to the compound having a nitroxy radical or nitroxide group. By the same operation, the polarizing film, the double-sided protective polarizing film, and the pseudo image display apparatus (laminated body) were produced. The single transmittance of the polarizing film was 40.0%.

<Example 3>

<Preparation of a polarizing film, a polarizing film, and a pseudo image display device (laminated body)>

Preparation of a polarizing film WHEREIN: It is the same as Example 1 except having used the compound which has the nitroxy radical represented by General formula (8), or a nitroxide group instead of General formula (9) for both adhesive agents to be used. By operation of , a polarizing film, a double-sided protective polarizing film, and a pseudo image display device (laminated body) were produced. The single transmittance of the polarizing film was 39.6%.

<Example 4>

<Preparation of a polarizing film, a polarizing film, and a pseudo image display device (laminated body)>

In the preparation of the polarizing film, as an adhesive, a polyvinyl alcohol resin containing an acetoacetyl group, methylolmelamine, and a compound having a nitroxy radical or nitroxide group represented by the general formula (6) are used in a weight ratio of 7:2:1. Except having used the aqueous solution to contain, it is operation similar to Example 1, and produced the polarizing film, the double-sided protective polarizing film, and the pseudo image display apparatus (laminated body). The single transmittance of the polarizing film was 39.7%.

<Comparative Example 1>

<Preparation of a polarizing film, a polarizing film, and a pseudo image display device (laminated body)>

Preparation of a polarizing film WHEREIN: Except not having added the compound which has the nitroxy radical represented by General formula (9), or a nitroxide group, it is operation similar to Example 1, and a polarizing film, a polarizing film, and A pseudo image display device (laminated body) was produced. The single transmittance of the polarizing film was 39.6%.

The above-mentioned [evaluation of the single transmittance in a high-temperature environment] was performed using the pseudo image display apparatus (laminated body) of the Example and comparative example obtained above. A result is shown in Table 1.

Claims (8)

A polarizing film in which a transparent protective film is bonded to at least one surface of the polarizing film via an adhesive layer, the polarizing film comprising:
The polarizing film is formed by adsorption orientation of iodine on a polyvinyl alcohol-based film,
The adhesive layer contains a compound having a nitroxy radical, or a nitroxide group,
Content of the compound which has the said nitroxy radical or a nitroxide group in the said adhesive bond layer is 1 weight% or more, The polarizing film characterized by the above-mentioned. The method of claim 1,
The polarizing film, characterized in that the compound having the nitroxy radical or nitroxide group is an N-oxyl compound. 3. The method according to claim 1 or 2,
Content of the compound which has the said nitroxy radical or a nitroxide group in the said adhesive bond layer is 70 weight% or less, The polarizing film characterized by the above-mentioned. The polarizing film of Claim 1 or 2 is bonded by the optical layer, The laminated polarizing film characterized by the above-mentioned. The polarizing film of Claim 1 or 2 is bonded by the image display cell, The image display panel characterized by the above-mentioned. The laminated polarizing film of Claim 4 is bonded by the image display cell, The image display panel characterized by the above-mentioned. A front transparent member is provided on the polarizing film side of the image display panel of Claim 5, The image display apparatus characterized by the above-mentioned. A front transparent member is provided on the laminated polarizing film side of the image display panel of Claim 6, The image display apparatus characterized by the above-mentioned.