CN111837061B - Polarizing film, laminated polarizing film, image display panel, and image display device - Google Patents

Abstract

The present invention provides a polarizing film in which a transparent protective film is bonded to at least one side of the polarizing film via an adhesive layer, wherein the polarizing film is formed by adsorbing iodine to a polyvinyl alcohol-based film and orienting it, and the adhesive The binder layer contains a compound having a nitroxyl radical or a nitroxyl group. This polarizing film is excellent in the effect of suppressing the decrease in the transmittance of the monomer caused by the coloring of the polarizing film in a high temperature environment.

Description

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

technical field

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

Background technique

Conventionally, as polarizing films used in various image display devices such as liquid crystal display devices and organic EL display devices, from the viewpoint of having both high transmittance and high degree of polarization, dyed (containing iodine, dichroic dyes) have been used. and other dichroic substances) polyvinyl alcohol film. This polarizing film is produced by subjecting the polyvinyl alcohol-based film to various treatments such as swelling, dyeing, cross-linking, and stretching in a bath, and then subjecting the polyvinyl alcohol-based film to washing treatment, followed by drying. In addition, the said polarizing film is used normally as a polarizing film (polarizing plate) which bonded the protective film, such as cellulose triacetate, on one surface or both surfaces with an adhesive agent.

The above-mentioned polarizing film is used in the form of a laminated polarizing film (optical laminate) by laminating other optical layers as necessary, and the above-mentioned polarizing film or the above-mentioned laminated polarizing film (optical laminate) is bonded to each other via a pressure-sensitive adhesive layer and an adhesive layer. The various image display devices described above are used between image display units such as liquid crystal cells and organic EL elements, and front transparent members such as a visible-side front transparent plate (window layer) and a touch panel.

In recent years, such various image display devices have been 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 uses are expanding. Along with this, the above-mentioned polarizing film and the above-mentioned laminated polarizing film are further required to have high durability in a more severe environment (for example, a high-temperature environment) than conventional requirements, and it has been proposed to ensure such durability as an object. Polarizing film (Patent Document 1).

In addition, in general, it is known that dye-based polarizing films using dichroic dyes such as azo compounds are compared with iodine-based polarizing films (polarizing films formed by adsorbing iodine to a polyvinyl alcohol-based film and orienting them). Excellent light resistance under high temperature and high humidity conditions (Patent Document 2), it is disclosed that in order to improve the discoloration of the polarizing plate having the dye-based polarizing film in the light resistance test, the adhesive used for the polarizing plate contains hindered Amine compound (Patent Document 3).

prior art literature

Patent Literature

Patent Document 1: Japanese Patent Publication No. 2012-516468

Patent Document 2: Japanese Patent Laid-Open No. 2001-240762

Patent Document 3: Japanese Patent Laid-Open No. 2005-338343

SUMMARY OF THE INVENTION

problem to be solved by invention

On the other hand, when the polarizing film and the laminated polarizing film using the iodine-based polarizing film, which is considered to be inferior in light resistance under high temperature and high humidity conditions compared with the dyeing-based polarizing film as described above, are exposed to a high temperature environment, There is a problem in that the polarizing film is colored and the transmittance of its monomer is lowered. In particular, the image display device formed by bonding the above-mentioned polarizing film or laminated polarizing film between the image display unit and the front transparent member via the pressure-sensitive adhesive layer or the adhesive layer has conspicuous coloration of the polarizing film, and the A reduction in bulk transmittance becomes a significant problem.

In view of the above circumstances, an object of the present invention is to provide a polarizing film which is excellent in the effect of suppressing the decrease in the transmittance of the monomer due to the coloring of the 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 reduction in the transmittance of a single substance due to the coloring of the polarizing film.

way of solving the problem

That is, the present invention relates to a polarizing film in which a transparent protective film is bonded to at least one surface of a polarizing film via an adhesive layer, wherein the polarizing film is formed by adsorbing iodine to a polyvinyl alcohol-based film and orienting it, The said adhesive bond layer contains the compound which has a nitroxyl radical or a nitroxyl group.

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

Moreover, this invention relates to the image display panel in which the said polarizing film or the said laminated polarizing film is bonded to the image display unit.

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

effect of invention

The details of the action mechanism of the effect of the polarizing film of the present invention are unclear, but are estimated as follows. However, the present invention can be explained without 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 containing a compound having a nitroxyl radical or a nitroxyl group. In addition, the above-mentioned partiality is formed by adsorbing and orienting iodine to the polyvinyl alcohol-based film. As described in the above-mentioned Patent Documents 2 and 3, in general, it is considered that an iodine-based polarizing film is inferior in durability such as heat resistance as compared with a dye-based polarizing film. In the dehydration reaction of polyvinyl alcohol, the deterioration phenomenon of polyolefination caused by the dehydration reaction is promoted.

On the other hand, when the compound having a nitroxyl radical or a nitroxyl group contained in the adhesive layer of the present invention is exposed to a high-temperature environment, it is estimated that a part of the compound having a nitroxyl radical or a nitroxyl group is It is eluted from the adhesive layer and penetrates into the iodine-based polarizing film close to the adhesive layer. In particular, in an image display device in which a front transparent member, the polarizing film, and an image display unit are laminated in this order, it is presumed that the compound having a nitroxyl radical or a nitroxyl group contained in the adhesive layer is exposed to high temperature. In the case of the environment, it moves (retains) inside the image display device together with the moisture existing in the interior (moisture existing in the adhesive layer, the adhesive layer, etc.), so the nitroxyl radical or nitroxyl group has A part of the compound easily penetrates into the above-mentioned iodine-based polarizing film. As a result, it is presumed that the compound having nitroxyl radicals or nitroxyl groups in the polarizing film can efficiently capture the radicals generated in the above-mentioned polyolefination reaction in a high temperature environment, and therefore, the polarizing film of the present invention can suppress the polarization caused by polarized light. Monomer transmittance decreases due to coloration of the film.

Detailed ways

<Compounds having nitroxyl radicals or nitroxyl groups>

As the compound having a nitroxyl radical or a nitroxyl group of the present invention, from the viewpoint of having a relatively stable radical at room temperature and in the air, an N-hydrocarbyloxy compound (having CN(-C)-O ^as a As the functional group compound (O ^· represents an oxygen radical)), a known compound can also be used. As an N-hydrocarbyloxy compound, the compound etc. which have the organic group of the following structure are mentioned, for example. The above-mentioned compounds having a nitroxyl radical or a nitroxyl group may be used alone or in combination of two or more.

[Chemical formula 1]

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

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.

[Chemical formula 2]

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

[Chemical formula 3]

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

[Chemical formula 4]

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

[Chemical formula 5]

(In the general formula (5), R ¹ to R ⁵ and n have the same meanings as described 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 hydroxyl group, or an aryl group. )

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

Moreover, as said N-hydrocarbyloxy compound, Japanese 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 mentioned, for example N-alkoxy compounds described in .

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

[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]

In addition, the molecular weight of the compound having a nitroxyl radical or a nitroxyl group is preferably 1000 or less, more preferably 500 or less, and even more preferably 300 or less, from the viewpoint of efficiently capturing the radicals generated in the polyolefination reaction.

＜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 via an adhesive layer, the polarizing film is formed by adsorbing iodine to a polyvinyl alcohol-based film and orienting, and the adhesive layer contains The above-mentioned compound having a nitroxyl radical or a nitroxyl group.

＜Polarizing film＞

The polarizing film of the present invention is formed by adsorbing iodine to a polyvinyl alcohol-based film and orienting it. As the polyvinyl alcohol (PVA)-based film described above, a polyvinyl alcohol (PVA)-based film that has light transmittance in the visible light region and is obtained by dispersing and adsorbing iodine can be used without particular limitation. Moreover, the thickness of the PVA type film used as a film roll is about 1-100 micrometers normally, More preferably, it is about 1-50 micrometers.

As a material of the said polyvinyl alcohol type film, polyvinyl alcohol or its derivative(s) can be mentioned. Examples of derivatives of the polyvinyl alcohol include: polyvinyl formal, polyvinyl acetal; olefins such as ethylene and propylene; unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and alkyl groups thereof Derivatives obtained by modifying esters, acrylamides, etc. The average degree of polymerization of the polyvinyl alcohol is preferably about 100 to 10,000, more preferably about 1,000 to 10,000, and even more preferably about 1,500 to 4,500. The degree of saponification of the polyvinyl alcohol is preferably 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 based on JISK6726.

It is preferable that content of the said iodine of the said polarizing film is 1 weight% or more and 15 weight% or less. In the polarizing film, the content of the iodine is preferably 1.5 wt % or more, more preferably 2 wt % or more, from the viewpoint of suppressing discoloration during the durability test, and from the viewpoint of preventing polyolefinization, preferably It is 12 weight% or less, More preferably, it is 10 weight% or less.

The above-mentioned polarizing film can be produced by, for example, immersing the above-mentioned polyvinyl alcohol-based film in an aqueous solution of iodine, dyeing, and stretching to 3 to 7 times the original length. If necessary, it may be immersed in an aqueous solution containing boric acid, potassium iodide, or the like. Further, the polyvinyl alcohol-based film may be immersed in water and washed with water before dyeing, if necessary. Washing the polyvinyl alcohol-based film with water has the effect of swelling the polyvinyl alcohol-based film and preventing unevenness such as uneven dyeing in addition to washing away the dirt and anti-blocking agent on the surface of the polyvinyl alcohol-based film. Stretching may be performed after dyeing with iodine, or may be stretched while dyeing, or may be dyed with iodine after stretching. Stretching can also be performed in an aqueous solution of boric acid, potassium iodide, or the like, or in a water bath.

The thickness of the polarizing film is preferably about 1 to 50 μm, and more preferably about 1 to 25 μm. In particular, in order to obtain a polarizing film with a thickness of 8 μm or less, the above-mentioned Japanese Patent Laid-Open No. 2009-098653, Japanese Patent Laid-Open No. 2012-073580, Japanese Patent Laid-Open No. 2013-238640, and Japanese Patent No. 4691205 can be applied , Japanese Patent No. 4751481, etc., a method for producing a thin polarizing film using a laminate comprising a polyvinyl alcohol-based resin layer formed on a resin substrate such as a thermoplastic resin as the polyvinyl alcohol-based film.

<Adhesive layer>

The adhesive bond layer of this invention is formed of an adhesive agent. As the above-mentioned adhesive, various adhesives used for polarizing films can be applied, for example, isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based adhesives, Water-based polyester, etc. These adhesives are usually used as an adhesive (aqueous adhesive) formed from an aqueous solution, and contain 0.5 to 60% by weight of solid content. Among these, polyvinyl alcohol-based adhesives are preferred, and acetoacetyl group-containing polyvinyl alcohol-based adhesives are more preferred.

The above-mentioned aqueous adhesive may contain a crosslinking agent. As the above-mentioned crosslinking agent, a compound having at least two functional groups reactive with components such as a polymer constituting an adhesive can be generally used in one molecule, and examples thereof include alkylene diamines; isocyanates; Oxygens; aldehydes; amino-formaldehyde such as methylol urea, methylol melamine, etc. The compounding quantity of the crosslinking agent in an adhesive agent is about 10-60 weight part normally with respect to 100 weight part of components, such as a polymer which comprises an adhesive agent.

烷二醇二丙烯酸酯、EO改性二甘油四丙烯酸酯等多官能单体作为交联成分。另外，作为阳离子聚合固化型粘接剂，也可以使用具有环氧基、氧杂环丁基的化合物。具有环氧基的化合物只要是在分子内具有至少2个环氧基的化合物就没有特别限定，可以使用通常已知的各种固化性环氧化合物。In addition to the above-mentioned adhesives, active energy ray-curable adhesives such as ultraviolet-curable adhesives and electron beam-curable adhesives can be exemplified. As said active energy ray-curable adhesive agent, (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. Examples of compounds having a (meth)acryloyl group include (meth)acrylic acid chain alkyl esters having 1 to 20 carbon atoms, (meth)acrylic acid alicyclic alkyl esters, and (meth)acrylic acid polycyclic esters. Alkyl (meth)acrylates such as formula alkyl esters; hydroxyl group-containing (meth)acrylates; epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate and the like. The (meth)acrylate-based adhesive may contain hydroxyethyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methoxymethyl (meth)acrylamide, N- Nitrogen-containing monomers such as ethoxymethyl (meth)acrylamide, (meth)acrylamide, and (meth)acryloyl morpholine. The (meth)acrylate-based adhesive may contain tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, cyclic trimethylolpropane methylal acrylic acid Ester, Di

Multifunctional monomers such as alkanediol diacrylate and EO modified diglycerol tetraacrylate are used as crosslinking components. Moreover, as a cationic polymerization curable adhesive agent, the compound which has an epoxy group and an oxetanyl group can also be used. The compound having an epoxy group is not particularly limited as long as it has at least two epoxy groups in the molecule, and various commonly known curable epoxy compounds can be used.

The said adhesive agent may contain suitable additives as needed. Examples of the above-mentioned additives include coupling agents such as silane coupling agents and titanium coupling agents, adhesion promoters such as ethylene oxide, ultraviolet absorbers, anti-deterioration agents, dyes, processing aids, ion scavengers, Antioxidant, tackifier, filler, plasticizer, leveling agent, foam inhibitor, antistatic agent, heat-resistant stabilizer, hydrolysis-resistant stabilizer, etc.

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

It is preferable that content of the compound which has the said nitroxyl radical or a nitroxyl group in the said adhesive bond layer in an adhesive bond layer is 70 weight% or less. The content of the hindered amine compound in the adhesive layer is preferably 1 wt % or more, It is more preferably 5% by weight or more, still more preferably 10% by weight or more, and preferably 60% by weight or less, more preferably 50% by weight or less.

＜Transparent protective film＞

The transparent protective film of the present invention is not particularly limited, and various transparent protective films used for polarizing films can be used. As a material constituting the above-mentioned transparent protective film, for example, thermoplastic resins excellent in transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy can be used. Examples of the thermoplastic resin include cellulose ester-based resins such as cellulose triacetate, polyester-based resins such as polyethylene terephthalate and polyethylene naphthalate, polyethersulfone-based resins, and polyethylene terephthalate-based resins. Sulfone-based resins, polycarbonate-based resins, polyamide-based resins such as nylon and aramid, polyimide-based resins, polyolefin-based resins such as polyethylene, polypropylene, and ethylene-propylene copolymers, (methyl) ) acrylic resin, cyclic or cyclic polyolefin resin having norbornene structure (norbornene-based resin), polyacrylic resin, polystyrene-based resin, polyvinyl alcohol-based resin and mixtures thereof. Moreover, the said transparent protective film can use the cured layer formed of thermosetting resins, such as (meth)acrylic type, urethane type, acrylic urethane type, epoxy type, silicone type, or UV-curable resin. Among these, cellulose ester-based resins, polycarbonate-based resins, (meth)acrylic-based resins, cyclic polyolefin-based resins, and polyester-based resins are preferred.

The thickness of the above-mentioned transparent protective film can be appropriately determined, but in general, from the viewpoints of strength, handling properties, etc., and thin layer properties, it is preferably about 1 to 500 μm, more preferably about 1 to 300 μm, and even more preferably about 5 to 500 μm. 100μm or so.

When bonding the said transparent protective film to both surfaces of the said polarizing film, the transparent protective film of the said both surfaces may be the same, and may differ.

As the transparent protective film, a retardation plate having a front phase difference of 40 nm or more and/or a thickness direction retardation of 80 nm or more can be used. Usually, the front phase difference is controlled to be in the range of 40 to 200 nm, 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 above-mentioned transparent protective film, since the retardation plate also functions as a transparent protective film, thickness reduction can be achieved.

Examples of the retardation plate include a birefringent film obtained by unidirectionally or biaxially stretching a polymer material, an alignment film of a liquid crystal polymer, and a phase formed by supporting an alignment layer of a liquid crystal polymer with a film. Bad board, etc. The thickness of the retardation plate is also not particularly limited, but is usually about 20 to 150 μm. In addition, it can be used by bonding the said phase plate to the transparent protective film which does not have retardation.

Any appropriate additives such as ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, anti-color agents, flame retardants, antistatic agents, pigments, and colorants may be contained in the transparent protective film. When an ultraviolet absorber is contained in the said transparent protective film especially, the light resistance of a polarizing film can be improved.

Functional layers such as a hard coat layer, an anti-reflection layer, an anti-adhesion layer, a diffusion layer, or an anti-glare layer may be provided on the side of the above-mentioned transparent protective film that is not adhered to the polarizing film. In addition, the functional layers such as the above-mentioned hard coat layer, antireflection layer, antiadhesion layer, diffusion layer, antiglare layer, etc. may be provided in addition to the protective film itself, and may be provided as a separate layer from the protective film.

In the polarizing film of the present invention, at least one side of the polarizing film may be bonded to the transparent protective film via the adhesive layer, and the other side (the other side) of the polarizing film may be attached to the transparent protective film or the polarizing film. The other side (the other side) and the above-mentioned functional layer are usually bonded together via an adhesive layer or the above-mentioned adhesive layer. In addition, on the other surface (other surface) of the said polarizing film, you may directly bond the image display unit and the front surface transparent member mentioned later via the said adhesive bond layer.

Various adhesives used for polarizing films can be applied as the adhesive for forming the above-mentioned adhesive layer, for example, rubber-based adhesives, acrylic-based adhesives, silicone-based adhesives, amino Formate-based adhesives, vinyl alkyl ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, and the like. Among these, an acrylic adhesive is preferable. 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 above-mentioned pressure-sensitive adhesive to a separator etc. after peeling treatment, drying it, forming a pressure-sensitive adhesive layer, and transferring it to a polarizing film or the like can be exemplified; or A method of forming an adhesive layer by applying the above-mentioned adhesive to a polarizing film or the like and drying it, and the like. The thickness of the said adhesive layer is not specifically limited, For example, it is about 1-100 micrometers, Preferably it is about 2-50 micrometers.

The above-mentioned transparent protective film and the above-mentioned polarizing film, or the above-mentioned polarizing film and the above-mentioned functional layer may be laminated with intervening layers such as a surface modification treatment layer, an easy-adhesive layer, a barrier layer, and a refractive index adjustment layer.

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

Examples of the easy-adhesive agent that forms the above-mentioned easy-adhesive layer include polyester skeletons, polyether skeletons, polycarbonate skeletons, polyurethane skeletons, silicones, polyamide skeletons, polyimide skeletons, polyamide skeletons, and polyamide skeletons. Forming material of various resins such as vinyl alcohol skeleton. The said easy-adhesion layer is normally provided in a protective film in advance, and the easy-adhesion layer side of this protective film and a polarizing film can be laminated|stacked via the said adhesive bond layer or the said adhesive bond layer.

The above-mentioned barrier layer is a layer having a function of preventing impurities such as oligomers and ions eluted from the transparent protective film or the like from moving (invading) into the polarizing film. The above-mentioned barrier layer should just be a layer that has transparency and can prevent impurities eluted from a transparent protective film or the like, and examples of materials for forming the barrier layer include urethane prepolymer-based materials, cyanoacrylic acid Ester-based forming materials, epoxy-based forming materials, and the like.

The said refractive index adjustment layer is a layer provided in order to suppress the fall of the transmittance|permeability accompanying reflection between layers with different refractive indexes, such as the said transparent protective film and a polarizing film. As a refractive index adjustment material which forms the said refractive index adjustment layer, the formation agent containing various resins, such as a silica type, an acryl type, an acryl-styrene type, a melamine type, and an additive, is mentioned, for example.

<Laminated polarizing film>

In the laminated polarizing film (optical laminated body) of this invention, the said polarizing film is bonded to an optical layer. The above-mentioned optical layer is not particularly limited, for example, one or more layers of reflective plates, semi-transmissive plates, retardation plates (including wave plates such as 1/2, 1/4, etc.), visual compensation films, etc. can be used in liquid crystal display devices, etc. The formation of optical layers sometimes used. Examples of the above-mentioned laminated polarizing film include, in particular, a reflective polarizing film or a semi-transmissive polarizing film obtained by laminating a reflective plate or a semi-transmissive reflecting plate on the above-mentioned polarizing film, and a film obtained by laminating a retardation plate on the above-mentioned polarizing film. An elliptically polarizing film or a circular polarizing film, a wide viewing angle polarizing film in which a viewing angle compensation film is further laminated on the above-mentioned polarizing film, or a polarizing film in which a brightness improving film is further laminated on the above-mentioned polarizing film.

The polarizing film or the laminated polarizing film may be provided on one or both sides for attaching image display units such as liquid crystal cells and organic EL elements to other members such as front transparent plates on the visible side and front transparent members such as touch panels. combined adhesive layer. As this adhesive bond layer, an adhesive bond layer is preferable. The adhesive for forming the above-mentioned adhesive layer is not particularly limited, and for example, polymers such as acrylic polymers, silicone polymers, polyesters, polyurethanes, polyamides, polyethers, fluorines, and rubbers can be appropriately selected. It is used as a binder for the base polymer. In particular, adhesives that are excellent in optical transparency, such as adhesives containing an acrylic polymer, exhibit moderate wettability, aggregation properties, adhesiveness, weather resistance, heat resistance, and the like can be preferably used.

Provision of the pressure-sensitive adhesive layer on one side or both sides of the polarizing film and the laminated polarizing film can be performed in an appropriate manner. The arrangement of the pressure-sensitive adhesive layer includes, for example, a method of preparing a pressure-sensitive adhesive solution and directly setting it on the above-mentioned polarizing film or the above-mentioned laminated polarizing film by a suitable spreading method such as a casting method or a coating method; or The pressure-sensitive adhesive layer is formed on the separator, and it is transferred to the above-mentioned polarizing film, the above-mentioned method of laminating the polarizing film, and the like. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use, adhesive force, and the like, but is generally 1 to 500 μm, preferably 5 to 200 μm, and more preferably 10 to 100 μm. The material in which the pressure-sensitive adhesive layer is provided on at least one surface of the polarizing film and the laminated polarizing film in this manner is referred to as a pressure-sensitive adhesive layer-attached polarizing film or a pressure-sensitive adhesive layer-attached laminated polarizing film.

It is preferable to temporarily adhere a separator to cover the exposed surface of the pressure-sensitive adhesive layer until it is actually used, for the purpose of preventing contamination and the like. Thereby, it is possible to prevent contamination and the like of the pressure-sensitive adhesive layer in a normal processing state. As the separator, if necessary, suitable release agents such as silicone-based, long-chain alkyl-based, fluorine-based, molybdenum sulfide, etc. can be used, for example, plastic films, rubber sheets, paper, cloth, non-woven fabrics, nets, and foam sheets can be used. , metal foil, their laminates and other suitable thin-layer bodies are coated with separators and the like.

<Image Display Panel and Image Display Device>

The image display panel of the present invention is formed by bonding the above-mentioned polarizing film or the above-mentioned laminated polarizing film to an image display unit. Moreover, the image display apparatus of this invention is equipped with the front surface transparent member on the polarizing film or laminated|stacked polarizing film side (viewable side) of the said image display panel.

As said image display cell, a liquid crystal cell, an organic EL cell, etc. are mentioned, for example. As the liquid crystal cell, for example, 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 external light and light from the light source can be used. Any of the liquid crystal cells. When the above-mentioned liquid crystal cell utilizes light from a light source, the image display device (liquid crystal display device) also includes a polarizing film and a light source on the side opposite to the visible side of the image display cell (liquid crystal cell). The polarizing film on the light source side and the liquid crystal cell are preferably bonded together via a suitable adhesive layer. As a driving method of the above-mentioned liquid crystal cell, for example, any type of method such as a VA mode, an IPS mode, a TN mode, an STN mode, and a bend orientation (π type) can be exemplified.

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 laminated on a transparent substrate to form a light-emitting body (organic electroluminescent light-emitting body) can be suitably used. The above-mentioned organic light-emitting layer is a laminate of various organic thin films, and various layer structures can be adopted, including, for example, a hole injection layer made of triphenylamine derivatives and the like, and a fluorescent organic solid such as anthracene. A laminate of light-emitting layers, a laminate of these light-emitting layers and an electron injection layer made of a perylene derivative or the like, or a laminate of a hole injection layer, a light-emitting layer, and an electron injection layer, or the like.

As a front surface transparent member arrange|positioned on the visible side of the said image display unit, a front surface transparent plate (window layer), a touch panel, etc. are mentioned, for example. As the above-mentioned front transparent plate, a transparent plate having suitable mechanical strength and thickness can be used. As such a transparent plate, for example, a transparent resin plate such as an acrylic resin and a polycarbonate resin, a glass plate, or the like can be used. As the above-mentioned touch panel, for example, various touch panels of a resistive film method, an electrostatic capacitance method, an optical method, and an ultrasonic method, a glass plate having a touch sensor function, a transparent resin plate, and the like can be used. When a capacitive touch panel is used as the front transparent member, it is preferable to provide a front transparent plate made of glass or a transparent resin plate on the side closer to the visible side 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 2400, a degree of saponification of 99.9 mol%, and a thickness of 45 μm was prepared. The polyvinyl alcohol film was immersed in a swelling bath (water bath) at 20° C. for 30 seconds between rolls with different peripheral speed ratios to swell while stretching 2.2 times in the conveying direction (swelling step), and then, at 30 In a dyeing bath at °C (an aqueous iodine solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 with respect to 100 parts by weight of water), the concentration was adjusted so that the iodine concentration of the polarizing film finally obtained would be 3.60% by weight. While being immersed for 30 seconds, the original polyvinyl alcohol film (polyvinyl alcohol film completely unstretched in the conveying direction) was stretched 3.3 times in the conveying direction as a reference (dyeing step). Next, the dyed polyvinyl alcohol film was immersed for 28 seconds in a cross-linking bath (aqueous solution with a boric acid concentration of 3.0 wt % and a potassium iodide concentration of 3.0 wt %) at 40° C., and the original polyvinyl alcohol film was used as a reference. It stretched to 3.6 times in the conveyance direction (crosslinking process). Further, the obtained polyvinyl alcohol film was immersed for 60 seconds in a stretching bath (aqueous solution with a boric acid concentration of 4.0 wt % and a potassium iodide concentration of 5.0 wt %) at 61° C., and was transported using the original polyvinyl alcohol film as a reference. After stretching to 6.0 times in the direction (stretching step), it was immersed in a cleaning bath (aqueous solution having a potassium iodide concentration of 2.0 wt %) at 35° C. for 10 seconds (cleaning step). The washed polyvinyl alcohol film was dried at 40° C. for 30 seconds to prepare a polarizing film. The thickness of the polarizing film was 18 μm.

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

About the polarizing film, the iodine concentration (weight %) was calculated|required by the following formula using the fluorescent X-ray analyzer (The Rigaku Corporation make, brand name "ZSX-PRIMUSIV", measurement diameter: φ20mm).

Iodine concentration (wt%)=14.474×(fluorescence X-ray intensity)/(film thickness) (kcps/μm)

In addition, although the coefficient at the time of calculating a density|concentration differs depending on a measuring apparatus, this coefficient can be calculated|required using an appropriate calibration curve.

<Production of polarizing film>

As the binder, a polyvinyl alcohol resin having an acetoacetyl group (average degree of polymerization: 1200, degree of saponification: 98.5 mol%, degree of acetoacetylation: 5 mol%) containing an acetoacetyl group in a weight ratio of 3:1:4 was used; An aqueous solution of methyl melamine and a compound having a nitroxyl radical or a nitroxyl group represented by the general formula (9). Using this adhesive, a cellulose triacetate film having a thickness of 47 μm with a hard coat layer (water vapor transmission rate: 342 g/(m ² ·24 h) was laminated on both sides of the polarizing film obtained above as a transparent protective film by a roll laminator. ), Konica Minolta, trade name "KC4UYW"), then heated and dried in an oven (temperature of 60°C, time of 4 minutes) to produce a polarizing film with a transparent protective film attached to both sides of the polarizing film. membrane. The single transmittance of the polarizing film was 39.7%.

[Chemical formula 9]

<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-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a condenser. Furthermore, with respect to 100 parts of the above-mentioned monomer mixture (solid content), 0.1 part of 2,2'-azobisisobutyronitrile as a polymerization initiator was added together with 100 parts of ethyl acetate, and nitrogen gas was introduced while stirring slowly, After nitrogen substitution, the liquid temperature in the flask was maintained at around 55°C, and a polymerization reaction was performed for 8 hours to prepare a solution of an acrylic polymer having a weight average molecular weight (Mw) of 1,800,000. Then, with respect to 100 parts of solid content of the obtained acrylic polymer solution, an isocyanate crosslinking agent (manufactured by Tosoh Corporation, trade name "Takenate D110N", trimethylolpropane/xylylene diisocyanate plus product) 0.02 part, and 0.2 part of a silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-41-1056") to prepare a solution of an acrylic pressure-sensitive adhesive composition. Next, the solution of the acrylic pressure-sensitive adhesive composition obtained above was applied to a polyethylene terephthalate film (manufactured by Mitsubishi Chemical Polyester Film, trade name "" MRF38", separator), the thickness of the adhesive layer after drying was 20 μm, and drying was performed at 90° C. for 1 minute to form an adhesive layer on the surface of the separator. Next, the pressure-sensitive adhesive layer formed on the separator was transferred to one side of the polarizing film prepared above to prepare a pressure-sensitive adhesive layer-attached polarizing film.

<Production of an analog image display device (laminated body)>

The polarizing film with the pressure-sensitive adhesive layer obtained above was cut into a size of 40×40 mm so that the absorption axis of the polarizing film became the long side, and a glass plate (analog image display unit) was bonded through the pressure-sensitive adhesive layer. The other side of the film was bonded to another glass plate (simulated front transparent member) via an acrylic monomer-free adhesive (manufactured by Nitto Denko Co., Ltd., trade name "LUCIACS CS9868") with a thickness of 200 μm, and a simulated image display was produced. device (laminate).

[Evaluation of Transmittance of Monomer in High Temperature Environment]

The simulated image display device (laminated body) obtained above was allowed to stand in a hot air oven at a temperature of 105° C. for 48 hours, and the transmittance (ΔTs) of the monomers before and after injection (heating) was measured. The single transmittance was measured using a spectrophotometer (manufactured by Murakami Color Technology Laboratory Co., Ltd., product name "DOT-3") and evaluated based on the following criteria. The single transmittance is a Y value obtained by performing visibility correction with a 2-degree field of view (C light source) in JlS Z 8701-1982. In addition, the measurement wavelength is 380-700 nm (per 10 nm). The results are shown in Table 1.

ΔTs(%)=Ts ₄₈ −Ts ₀

Here, Ts ₀ is the single transmittance of the simulated image display device (laminate) before heating, and Ts ₄₈ is the single transmittance of the simulated image display device (laminate) after heating for 48 hours.

○: 5≥ΔTs(%)≥0

×: ΔTs(%)>5, or ΔTs(%)<0

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

<Example 2>

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

In the production of the polarizing film, a compound having a nitroxyl radical or a nitroxyl group represented by the general formula (10) was added to the two adhesives used, so that the weight ratio to the polyvinyl alcohol resin reached 4:3, Potassium hydroxide was added so as not to affect the curing reaction of the adhesive so that the molar ratio was 1:1 with respect to the compound having a nitroxyl radical or a nitroxyl group, and the pH was adjusted (neutralized) to remove Otherwise, a polarizing film, a double-sided protective polarizing film, and an analog image display device (laminated body) were produced in the same manner as in Example 1. The single transmittance of the polarizing film was 40.0%.

[Chemical formula 10]

<Example 3>

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

In the production of the polarizing film, in addition to using the compound represented by the general formula (8) having a nitroxyl radical or a nitroxyl group in place of the compound represented by the general formula (9) among the two adhesives used, the A polarizing film, a double-sided protective polarizing film, and an analog image display device (laminate) were produced in the same manner as in Example 1. The single transmittance of the polarizing film was 39.6%.

<Example 4>

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

In the production of the polarizing film, as an adhesive, an acetoacetyl group-containing polyvinyl alcohol resin, methylol melamine, and a nitroxyl radical represented by the general formula (6) were used in a weight ratio of 7:2:1. A polarizing film, a double-sided protective polarizing film, and an analog image display device (laminate) were produced in the same manner as in Example 1, except for an aqueous solution of a nitroxyl compound. The single transmittance of the polarizing film was 39.7%.

<Comparative Example 1>

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

A polarizing film, a polarizing film, and a simulated image 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 in the production of the polarizing film. Display device (laminated body). The single transmittance of the polarizing film was 39.6%.

The above-mentioned [Evaluation of Single Transmittance in a High-Temperature Environment] was performed using the simulated image display devices (laminates) of the Examples and Comparative Examples obtained above, and Table 1 shows the results.

[Table 1]

Claims (5)

1. A polarizing film, which is laminated with a transparent protective film through an adhesive layer on at least one side of the polarizing film, The polarizing film is formed by adsorbing iodine to a polyvinyl alcohol-based film and orienting it, The adhesive layer contains a compound having a nitroxyl radical or a nitroxyl group, The compound having a nitroxyl radical or a nitroxyl group is at least one selected from the compounds represented by the following general formula (1) and (8),

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

Content of the said compound which has a nitroxyl radical or a nitroxyl group in the said adhesive bond layer is 1 weight% or more. 2. The polarizing film of claim 1, wherein, The content of the compound having a nitroxyl radical or a nitroxyl group in the adhesive layer is 70% by weight or less. 3 . The laminated polarizing film in which the polarizing film according to claim 1 or 2 is bonded to an optical layer. 4 . 4 . An image display panel in which the polarizing film according to claim 1 or 2 or the laminated polarizing film according to claim 3 is attached to an image display unit. 5 . 5 . An image display device comprising a front transparent member on the polarizing film or the laminated polarizing film side of the image display panel according to claim 4 . 6 .