TW202023831A - Polarizing film, laminated polarizing film, image display panel and image display device - Google Patents

Abstract

Provided is a polarizing film in which a transparent protective film is adhered to at least one surface of the polarizing film with an adhesive layer therebetween, wherein the polarizing film is formed by adsorbing and orienting iodine on a polyvinyl alcohol-based film, and the adhesive layer includes a compound having a nitroxy radical or a nitroxide group. Said polarizing film exhibits excellent effects for suppressing a reduction in single transmittance by coloring the polarizing film in a high temperature environment.

Description

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

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

In the past, polarizing films used in various image display devices such as liquid crystal display devices or organic EL display devices have been dyed (contains dichroic properties such as iodine or dichroic dyes) in order to have both high transmittance and high polarization. Material) Polyvinyl alcohol film. The polarizing film is manufactured by subjecting the polyvinyl alcohol-based film to various treatments such as swelling, dyeing, cross-linking, and stretching in a bath, followed by a washing treatment and then drying. In addition, the aforementioned polarizing film is generally used as a polarizing film (polarizing plate) in which a protective film such as cellulose triacetate is bonded to one or both sides using an adhesive.

The aforementioned polarizing film can be laminated with other optical layers to form a multilayer polarizing film (optical laminate) according to need. The aforementioned polarizing film or the aforementioned multilayer polarizing film (optical laminate) is used in image display units such as liquid crystal cells or organic EL elements. It is bonded to the front transparent member (window layer) or touch panel, etc., through the adhesive layer or the adhesive layer to form the above-mentioned various image display devices for use.

In recent years, the various image display devices described above have been used in mobile devices such as mobile phones and tablet terminals, as well as in-vehicle image display devices such as car navigation devices or rear-illuminated monitor recorders. Wide spread. Therefore, the aforementioned polarizing film or the aforementioned laminated polarizing film is required to have high durability in a harsher environment (such as a high temperature environment) than previously required, and a polarizing film for the purpose of ensuring the durability is proposed ( Patent Document 1).

In addition, it is known that dye-based polarizing films using dichroic dyes such as azo compounds generally have better light resistance under high-temperature and high-humidity conditions than iodine-based polarizing films (formed by adsorption of iodine on polyvinyl alcohol-based films). The polarizing film) is excellent (Patent Document 2), and in order to improve the fading of the polarizing plate having the dye-based polarizing film in the light resistance test, it has been disclosed that the adhesive to be used for the polarizing plate may contain a hindered amine compound ( Patent Document 3).

Prior art literature Patent literature Patent Document 1: Japanese Special Form No. 2012-516468 Patent Document 2: Japanese Patent Application Publication No. 2001-240762 Patent Document 3: Japanese Patent Application Publication No. 2005-338343

Summary of the invention Problems to be solved by the invention On the other hand, as mentioned above, the polarizing film or laminated polarizing film of the iodine-based polarizing film, which is said to have worse light resistance under high-temperature and high-humidity conditions than the dyeing-based polarizing film, will color the polarizing film when exposed to a high temperature environment. , And there is the problem of reduced monomer transmittance. Especially an image display device constructed by bonding the above-mentioned polarizing film or laminated polarizing film through an adhesive layer or an adhesive layer between the image display unit and the front transparent member, the color of the polarizing film is remarkable, and there is a monomer The transmittance will be significantly reduced.

In view of the above circumstances, the object of the present invention is to provide a polarizing film that is excellent in the effect of suppressing the coloring of the polarizing film and the decrease in the transmittance of the monomer caused by the high temperature environment.

In addition, the 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 the monomer caused by the coloring of the polarizing film. Means to solve the problem

That is, the present invention relates to a polarizing film, which is formed by laminating a transparent protective film through an adhesive layer on at least one side of the polarizing film; the polarizing film is formed by iodine adsorption and orientation on the polyvinyl alcohol film; the adhesive layer Contains compounds with nitroxyl radicals or nitroxyl radicals.

Furthermore, the present invention relates to a laminated polarizing film, wherein the aforementioned polarizing film is bonded to an optical layer.

Moreover, the present invention relates to an image display panel in which the aforementioned polarizing film or the aforementioned multilayer polarizing film is bonded to the image display unit.

In addition, the present invention relates to an image display device including a front transparent member on the polarizing film or laminated polarizing film side of the image display panel.

Invention effect Although the details of the mechanism of the effect of the polarizing film of the present invention are still unclear, we guess as follows. However, the present invention may not be limited to the explanation of the mechanism of action.

The polarizing film of the present invention is a transparent protective film attached to at least one side of the polarizing film through an adhesive layer, and the adhesive layer contains a compound with nitroxide radicals or nitroxyl groups. In addition, the polarizing film is formed by adsorbing and oriented iodine to the polyvinyl alcohol film. As described in Patent Documents 2 and 3 above, in general, the durability of iodine-based polarizing films such as heat resistance is worse than that of dye-based polarizing films. It is presumed that the reason is that the iodine contained in the polarizing film promotes the deterioration of polyvinyl alcohol in a high-temperature environment. The dehydration reaction occurs due to the deterioration phenomenon called polyolefinization.

On the other hand, when the compound having nitroxyl radicals or nitroxyl groups contained in the aforementioned adhesive layer of the present invention is exposed to a high temperature environment, it is speculated that a part of the compound having nitroxyl radicals or nitroxyl groups will change from The adhesive layer dissolves and penetrates into the iodine-based polarizing film near the adhesive layer. Especially in an image display device constructed with a front transparent member, the aforementioned polarizing film, and an image display unit in sequence, the compound having nitroxide radicals or nitroxyl groups contained in the adhesive layer is exposed to a high temperature environment , It will move (retain) inside the image display device together with the moisture present inside (the moisture present in the adhesive layer or the adhesive layer, etc.), so it is speculated that a part of the compound with nitroxyl radicals or nitroxyl groups will It is easy to penetrate the above-mentioned iodine-based polarizing film. As a result, it is speculated that the compound having nitroxide radicals or nitroxyl groups in the polarizing film can efficiently capture the free radicals generated in the above-mentioned polyalkylene reaction in a high temperature environment, so the polarizing film of the present invention can suppress the coloring of the polarizing film Cause the monomer transmittance to decrease.

…(1) (通式(1)中，R¹ 表示氧自由基，R² 至R⁵ 獨立表示氫原子或碳原子數1~10烷基，n表示0或1)。此外，通式(1)中虛線部之左邊表示任意的有機基。The form used to implement the invention >Compounds with nitroxyl radicals or nitroxyl groups> From the viewpoint of having free radicals that are relatively stable at room temperature and in the air, the compounds having nitroxyl radicals or nitroxyl groups of the present invention include N-oxyl compounds (with C-N(-C)-O^・ Compounds as functional groups (O^・ It represents oxygen radical)), and known ones can be used. Examples of the N-oxy compound include compounds having organic groups of the following structures. The aforementioned compounds having nitroxyl radicals or nitroxyl groups may be used alone or in combination of two or more kinds. [Chemical formula 1]

…(1) (In the general formula (1), R¹ Represents oxygen free radicals, R² To R⁵ Independently represents a hydrogen atom or an alkyl group with 1 to 10 carbon atoms, and n represents 0 or 1). In addition, the left side of the dotted line in the general formula (1) represents an arbitrary organic group.

…(2) (通式(2)中，R¹ 至R⁵ 及n與上述相同，R⁶ 表示氫原子或碳原子數1~10烷基、醯基或伸芳基，n表示0或1)。 [化學式3]

…(3) (通式(3)中，R¹ 至R⁵ 及n與上述相同，R⁷ 及R⁸ 獨立表示氫原子或碳原子數1~10烷基、醯基或伸芳基)。 [化學式4]

…(4) (通式(4)中，R¹ 至R⁵ 及n與上述相同，R⁹ 至R¹¹ 獨立表示氫原子或碳原子數1~10烷基、醯基、胺基、烷氧基、羥基或伸芳基)。 [化學式5]

…(5) (通式(5)中，R¹ 至R⁵ 及n與上述相同，R¹² 表示氫原子或碳原子數1~10烷基、胺基、烷氧基、羥基或伸芳基)。Examples of the compound having the aforementioned organic group include compounds represented by the following general formulas (2) to (5). [Chemical formula 2]

…(2) (In the general formula (2), R ¹ to R ⁵ and n are the same as described above, R ⁶ represents a hydrogen atom or an alkyl group, acyl group or aryl group having 1 to 10 carbon atoms, and n represents 0 or 1 ). [Chemical formula 3]

...(3) (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, an acyl group or an aryl group having 1 to 10 carbon atoms). [Chemical formula 4]

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

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

In the aforementioned general formulas (1) to (5), R ² to R ⁵ are preferably an alkyl group having 1 to 6 carbon atoms, and more preferably an alkyl group having 1 to 3 carbon atoms, from the viewpoint of ease of acquisition. Furthermore, in the aforementioned general formula (2), from the viewpoint of ease of acquisition, R ^{6 is} preferably a hydrogen atom or an alkyl group with 1 to 10 carbon atoms, and a hydrogen atom is more preferable. In addition, in the aforementioned general formula (3), from the viewpoint of ease of acquisition, R ⁷ and R ^{8 are} preferably independently a hydrogen atom or an alkyl group with 1 to 10 carbon atoms, and a hydrogen atom is more preferable. In addition, in the aforementioned general formula (4), R ⁹ to R ^{11 are} preferably a hydrogen atom or an alkyl group with 1 to 10 carbon atoms from the viewpoint of ease of acquisition. In addition, in the aforementioned general formula (5), R ^{12 is} preferably a hydroxyl group, an amino group or an alkoxy group from the viewpoint of ease of acquisition. In the aforementioned general formulas (1) to (5), n is preferably 1 from the viewpoint of ease of obtaining.

In addition, the aforementioned N-oxy compound may include N-oxygen described in Japanese Patent Application Publication No. 2003-64022, Japanese Patent Application Publication No. 11-222462, Japanese Patent Application Publication No. 2002-284737, International Publication No. 2016/047655, etc. Base compound.

…(6) (通式(6)中，R表示氫原子或碳原子數1~10烷基、醯基或伸芳基)。 [化學式7]

…(7) [化學式8]

…(8)In addition, examples of the compound having a nitroxide radical or nitroxyl group include the following compounds. [Chemical formula 6]

...(6) (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). [Chemical formula 7]

…(7) [Chemical formula 8]

…(8)

In addition, from the viewpoint of efficiently trapping free radicals generated in the polyolefination reaction, the molecular weight of the aforementioned compound having nitroxyl radicals or nitroxyl groups is preferably 1000 or less, and more preferably 500 or less, and 300 or less Better yet.

>Polarizing Film> The polarizing film of the present invention is formed by laminating a transparent protective film on at least one side of the polarizing film through the adhesive layer; the polarizing film is formed by iodine adsorption and oriented to the polyvinyl alcohol film; the adhesive layer contains the nitroxide radical Or nitroxyl compounds.

>Polarizing Film> The polarizing film of the present invention is formed by adsorbing and oriented iodine to a polyvinyl alcohol film. The above-mentioned polyvinyl alcohol (PVA)-based film can be used without particular limitation, which has translucency in the visible light region and can dispersely adsorb iodine. In addition, the thickness of the PVA-based film generally used as the original plate is preferably about 1 to 100 μm, and more preferably about 1 to 50 μm.

Examples of the material of the polyvinyl alcohol-based film include polyvinyl alcohol or derivatives thereof. The derivatives of the aforementioned polyvinyl alcohol include, for example, polyvinyl formal and polyvinyl acetal; olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid and their alkyl esters; Waiting for reformers, etc. The average polymerization degree of the aforementioned polyvinyl alcohol is preferably about 100 to 10,000, preferably about 1,000 to 10,000, and more preferably about 1,500 to 4,500. In addition, the degree of saponification of the aforementioned polyvinyl alcohol is preferably about 80 to 100 mol%, and more preferably about 95 mol% to 99.95 mol%. In addition, the aforementioned average polymerization degree and the aforementioned saponification degree can be obtained in accordance with JIS K 6726.

The iodine content of the polarizing film is preferably 1% by weight or more and 15% by weight or less. From the viewpoint of inhibiting the fading during the durability test, the iodine content of the polarizing film is preferably 1.5% by weight or more, and more preferably 2% by weight or more, and from the viewpoint of preventing polyalkyleneization, the iodine content of the polarizing film is preferably It is 12% by weight or less, and more preferably 10% by weight or less.

The polarizing film can be produced by, for example, immersing the polyvinyl alcohol-based film in an aqueous solution of iodine for dyeing, and extending it to 3 to 7 times the original length. It can also be immersed in an aqueous solution such as boric acid or potassium iodide as required. Furthermore, if necessary, the polyvinyl alcohol-based film may be immersed in water for washing before dyeing. By washing the polyvinyl alcohol-based film with water, the dirt and anti-caking agent on the surface of the polyvinyl alcohol-based film can be washed. In addition, it also has the effect of swelling the polyvinyl alcohol-based film to prevent uneven dyeing. Stretching may be performed after dyeing with iodine, or it may be stretched while dyeing, or it may be dyed with iodine after stretching. It can also be extended in aqueous solutions such as boric acid or potassium iodide or in a water bath.

The thickness of the aforementioned polarizing film is preferably about 1-50μm, and more preferably about 1-25μm. In particular, in order to obtain a polarizing film with a thickness of 8 μm or less, the above-mentioned Japanese Patent Application Publication No. 2009-098653, Japanese Patent Application Publication No. 2012-073580, Japanese Patent Application Publication No. 2013-238640, Japanese Patent Application No. 4693205, The method of manufacturing a thin polarizing film disclosed in the specification of Japanese Patent No. 4751481 etc. uses 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.

>Adhesive layer> The adhesive layer of the present invention is formed of an adhesive. The aforementioned adhesive can be applied to various adhesives that can be used for polarizing films, and examples include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex-based, water-based polyesters, and the like. These adhesives are usually used as an adhesive composed of an aqueous solution (aqueous adhesive) and contain 0.5-60% by weight of solid content. Among them, polyvinyl alcohol-based adhesives are preferable, and polyvinyl alcohol-based adhesives containing acetyl acetyl groups are more preferable.

The aforementioned water-based adhesive may also include a crosslinking agent. The aforementioned crosslinking agent can generally be used for compounds having at least two functional groups reactive with components such as polymers constituting the adhesive in one molecule, and examples include alkylene diamines; isocyanates; epoxies ; Aldehydes; amine-formaldehyde such as methylolurea and methylolmelamine. The blending amount of the cross-linking agent in the adhesive is generally about 10-60 parts by weight relative to 100 parts by weight of the polymer and other components constituting the adhesive.

烷二醇二丙烯酸酯、EO改質二甘油四丙烯酸酯等多官能單體。又，陽離子聚合硬化型接著劑亦可使用具有環氧基或氧雜環丁烷基之化合物。具有環氧基之化合物只要是分子內具有至少2個環氧基者，則無特別限制，可使用一般已知的各種硬化性環氧化合物。In addition to the above-mentioned adhesives, active energy ray-curable adhesives such as ultraviolet-curable adhesives and electron beam-curable adhesives can be cited. Examples of the active energy ray-curable adhesive include (meth)acrylate-based adhesives. Examples of the curable component of the (meth)acrylate-based adhesive include a compound having a (meth)acryloyl group and a compound having a vinyl group. Compounds having (meth)acrylic acid groups include chain alkyl (meth)acrylates, alicyclic alkyl (meth)acrylates, and polycyclic alkyl (meth)acrylates with 1 to 20 carbon atoms. Alkyl (meth)acrylates such as esters; (meth)acrylates containing hydroxyl groups; (meth)acrylates containing epoxy groups such as glycidyl (meth)acrylate. The (meth)acrylate-based adhesive may also contain hydroxyethyl (meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-methoxymethyl (meth)acrylamide , N-ethoxymethyl (meth) acrylamide, (meth) acrylamide, (meth) acrylamide, mopholin and other nitrogen-containing monomers. The (meth)acrylate-based adhesive may contain tripropylene glycol diacrylate, 1,9-nonanediol diacrylate, tricyclodecane dimethanol diacrylate, and cyclic trimethylolpropane as crosslinking components. Acetal acrylate, two

Multifunctional monomers such as alkanediol diacrylate and EO modified diglycerol tetraacrylate. Moreover, the cationic polymerization hardening type adhesive agent can also use the compound which has an epoxy group or an oxetanyl group. 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 aforementioned adhesive may also contain appropriate additives as required. The aforementioned additives include, for example, silane coupling agents, titanium silane coupling agents and other silane coupling agents, adhesion promoters such as ethylene oxide, ultraviolet absorbers, anti-deterioration agents, dyes, processing aids, ion scavengers, antioxidants, and tackifiers. Agents, fillers, plasticizers, leveling agents, foam inhibitors, antistatic agents, heat-resistant stabilizers, hydrolysis-resistant stabilizers, etc.

The application of the adhesive may be performed on either the transparent protective film side (or the functional layer side described below) and the polarizing film side described later, or both. After bonding, a drying step is performed to form an adhesive layer composed of a coated dry layer. After the aforementioned drying step, ultraviolet rays or electron rays can be irradiated as needed. The thickness of the aforementioned adhesive layer is not particularly limited. When using water-based adhesives, etc., it is preferably about 30~5000nm, and more preferably about 100~1000nm, and when using ultraviolet-curing adhesives, electron beam-curing adhesives, etc. , Preferably about 0.1-100μm, more preferably about 0.5-10μm.

Taking the aforementioned adhesive layer as an example, the content of the aforementioned compound having nitroxide radicals or nitroxyl groups in the adhesive layer is preferably 70% by weight or less. From the viewpoint of suppressing the reduction of monomer transmittance caused by the coloring of the polarizing film in the aforementioned adhesive layer in a high temperature environment, the adhesive layer is preferably 1% by weight or more, more preferably 5% by weight or more, and preferably 10% by weight or more , And more preferably 60% by weight or less, and even 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 that can be used for polarizing films can be used. As the material constituting the aforementioned 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 aforementioned thermoplastic resins include: cellulose ester resins such as cellulose triacetate, polyester resins such as polyethylene terephthalate or polyethylene naphthalate, polyether-based resins, and poly-based resins. , Polycarbonate resins, polyamide resins such as nylon or aromatic polyamides, polyimide resins, polyolefin resins such as polyethylene, polypropylene, ethylene and propylene copolymers, (methyl) Acrylic resin, cyclic or cyclic polyolefin resin having a norbornene structure (norbornene resin), polyarylate resin, polystyrene resin, polyvinyl alcohol resin, and mixtures thereof. In addition, the aforementioned transparent protective film can be cured using thermosetting resins such as (meth)acrylic, urethane, acrylic urethane, epoxy, silicone, etc., or ultraviolet curing resins. Floor. Among these, cellulose ester resin, polycarbonate resin, (meth)acrylic resin, cyclic polyolefin resin, and polyester resin are preferable.

The thickness of the aforementioned transparent protective film can be appropriately determined, but generally from the viewpoints of strength, handling, etc., workability, thin layer properties, etc., it is preferably about 1 to 500 μm, preferably about 1 to 300 μm, and more preferably about 5 to 100 μm. .

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

The aforementioned transparent protective film can use a retardation plate having a frontal retardation of 40 nm or more and/or a retardation of 80 nm or more in the thickness direction. The frontal phase difference is usually controlled in the range of 40~200nm, and the thickness direction phase difference is usually controlled in the range of 80~300nm. When a phase difference plate is used as the above-mentioned transparent protective film, the phase difference plate can also function as a transparent protective film, and thus can be reduced in thickness.

As the above-mentioned retardation plate, for example, a birefringent film obtained by uniaxially or biaxially stretching a polymer material, an oriented film of a liquid crystal polymer, a film supporting an oriented layer of a liquid crystal polymer, etc. are mentioned. The thickness of the phase difference plate is not particularly limited, and is generally about 20 to 150 μm. In addition, it can also be used by bonding the aforementioned phase plate to a transparent protective film without phase difference.

The aforementioned transparent protective film may also contain any appropriate UV absorbers, antioxidants, slip agents, plasticizers, release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, colorants, etc. The additives. Especially when the ultraviolet absorber is contained in the transparent protective film, the light resistance of the polarizing film can be improved.

Functional layers such as hard coat, anti-reflection layer, anti-adhesion layer, diffusion layer and even anti-glare layer can be provided on the surface of the aforementioned transparent protective film that is not attached to the polarizing film. In addition, functional layers such as the above-mentioned hard coat layer, anti-reflection layer, anti-adhesion layer, diffusion layer, or anti-glare layer can be provided on the protective film itself, and can also be provided as an individual separate from the protective film.

In the polarizing film of the present invention, as long as at least one side of the polarizing film passes through the adhesive layer and the transparent protective film is bonded, the other side (the other side) of the polarizing film is connected to the transparent protective film or the polarizing film The other side (the other side) and the aforementioned functional layer are usually bonded through the adhesive layer or the aforementioned adhesive layer. In addition, on the other side (the other side) of the polarizing film, the image display unit described later or the front transparent member can also be directly bonded through the adhesive layer.

The adhesive that forms the aforementioned adhesive layer can be applied to various adhesives that can be used for polarizing films, such as rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkanes Base ether-based adhesives, polyvinyl alcohol-based adhesives, polyvinylpyrrolidone-based adhesives, polyacrylamide-based adhesives, cellulose-based adhesives, etc. Among them, acrylic adhesive is preferable. The aforementioned acrylic adhesive system contains an acrylic polymer as a base polymer, such as those described in JP 2017-75998 A and the like.

The method of forming the adhesive layer can be exemplified by the following method: the aforementioned adhesive is applied to a peel-off treated separator, etc., dried to form an adhesive layer, and then transferred to a polarizing film, etc.; The adhesive is applied to a polarizing film, etc., and dried to form an adhesive layer. The thickness of the aforementioned adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm, and preferably about 2 to 50 μm.

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

The surface modification treatment for forming the aforementioned surface modification layer includes, for example, corona treatment, plasma treatment, primer treatment, saponification treatment, and the like.

The easy-adhesive agent for forming the aforementioned easy-adhesive layer includes, for example, materials comprising various resins having the following skeletons: polyester skeleton, polyether skeleton, polycarbonate skeleton, polyurethane skeleton, polysiloxane, poly Amide skeleton, polyimide skeleton, polyvinyl alcohol skeleton, etc. The aforementioned easy-adhesive layer is usually provided on the protective film in advance, and the easy-adhesive layer side of the protective film and the polarizing film are laminated by the aforementioned adhesive layer or the aforementioned adhesive layer.

The aforementioned barrier layer has a function to prevent impurities such as oligomers or ions eluted from the transparent protective film from moving (intruding) into the polarizing film. The barrier layer may be a layer that has transparency and can prevent impurities eluted from a transparent protective film, etc. The material for forming the barrier layer includes, for example, a urethane prepolymer-based forming material and a cyanoacrylate-based forming material. , Epoxy-based forming materials, etc.

The refractive index adjustment layer is a layer provided in order to suppress a decrease in transmittance due to reflection between layers having different refractive indexes such as the transparent protective film and the polarizing film. Examples of the refractive index adjusting material that forms the refractive index adjusting layer include forming agents containing various resins and additives such as silica-based, acrylic-based, acrylic-styrene-based, and melamine-based resins.

>Laminated Polarizing Film> The laminated polarizing film (optical laminate) of the present invention is obtained by bonding the aforementioned polarizing film to the optical layer. The aforementioned optical layer is not particularly limited. For example, one layer or two or more layers such as reflective plates and semi-transmissive plates, retardation plates (including 1/2 and 1/4 wavelength plates), viewing angle compensation films, etc. can be used to form liquid crystals. Optical layer for display devices, etc. As the laminated polarizing film, for example, a reflective polarizing film or a semi-transmissive polarizing film formed by laminating a reflective plate or a semi-transmissive reflective plate on the polarizing film, and a retardation plate is laminated on the polarizing film. Elliptically polarizing film or circular polarizing film, a wide viewing angle polarizing film formed by laminating a viewing angle compensation film on the polarizing film, or a polarizing film formed by laminating a brightness enhancement film on the polarizing film.

Adhesive layers can also be attached to one or both sides of the aforementioned polarizing film or the aforementioned multilayer polarizing film, which can be used to bond image display units such as liquid crystal cells or organic EL elements to front transparent members such as a transparent plate on the viewing side or a touch panel. Other components. The adhesive layer is preferably an adhesive layer. The adhesive forming the aforementioned adhesive layer is not particularly limited, and acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine or rubber can be selected as appropriate. Such polymers are used as the base polymer. In particular, it can be suitably used, such as an acrylic polymer-containing adhesive, which has excellent optical transparency, can exhibit moderate wettability, cohesiveness, and adhesion, and has excellent weather resistance and heat resistance.

Attaching the adhesive layer to one side or both sides of the aforementioned polarizing film or the aforementioned multilayer polarizing film can be carried out by an appropriate method. The adhesive layer can be attached by, for example, the following methods: preparing an adhesive solution, and directly attaching it to the aforementioned polarizing film or the aforementioned multilayer polarizing film by a suitable spreading method such as a casting method or a coating method; A method of forming an adhesive layer on the surface and transferring it to the aforementioned polarizing film or the aforementioned multilayer polarizing film. The thickness of the aforementioned adhesive layer can be appropriately determined according to the purpose of use or adhesive strength, etc., generally 1~500μm, preferably 5~200μm, more preferably 10~100μm. As mentioned, the adhesive layer provided on at least one side of the polarizing film or the laminated polarizing film is referred to as an adhesive layer-attached polarizing film or an adhesive layer-attached laminated polarizing film.

In order to prevent the exposed surface of the aforementioned adhesive layer from being contaminated, it is advisable to temporarily attach and cover it with a separator before it is actually used. This can prevent the adhesive layer from being contaminated in the usual disposal state. As the aforementioned separators, for example, plastic films, rubber sheets, paper, cloth, non-woven fabrics, meshes, foam sheets or metal foils, and laminates of these can be used. Or long-chain alkyl-based, fluorine-based, or molybdenum sulfide and other suitable release agents are coated.

>Image display panel and image display device> The image display panel of the present invention is one in which the aforementioned polarizing film or the aforementioned laminated polarizing film is attached to the image display unit. In addition, the image display device of the present invention is provided with a front transparent member on the polarizing film or multilayer polarizing film side (viewing side) of the image display panel.

Examples of the aforementioned image display unit include a liquid crystal cell or an organic EL unit. The aforementioned liquid crystal cell can be used in, 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 a light source. Of any kind. When the aforementioned liquid crystal cell uses light from a light source, the image display device (liquid crystal display device) will also arrange a polarizing film on the side of the image display unit (liquid crystal cell) opposite to the viewing side, and will also arrange a light source. The polarizing film on the light source side and the liquid crystal cell should be attached through a suitable adhesive layer. The driving method of the aforementioned liquid crystal cell may use any type such as VA mode, IPS mode, TN mode, STN mode, or bend orientation (π-type).

The aforementioned organic EL unit can be suitably used, for example, 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 body). The aforementioned organic light-emitting layer is a laminate of various organic thin films. For example, the following various layers can be used: a laminate of a hole injection layer composed of triphenylamine derivatives and a light-emitting layer composed of a fluorescent organic solid such as anthracene; A laminate of the light-emitting layers and an electron injection layer composed of perylene derivatives, etc.; or a laminate of a hole injection layer, a light-emitting layer, and an electron injection layer.

The front transparent member disposed on the viewing side of the aforementioned image display unit may, for example, be a front transparent plate (window layer) or a touch panel. The aforementioned front transparent plate can be a transparent plate with appropriate mechanical strength and thickness. As the transparent plate, for example, a transparent resin plate such as acrylic resin or polycarbonate resin, or a glass plate can be used. As the aforementioned touch panel, various touch panels such as resistive film type, capacitive type, optical type, and ultrasonic type, or glass plate or transparent resin plate with touch sensing function can be used. When using a capacitive touch panel as the aforementioned front transparent member, it is advisable to provide a front transparent plate made of glass or a transparent resin plate at the side closer to the visibility than the touch panel. Example

Examples are listed below to illustrate the present invention in more detail, but the present invention is not limited to these examples.

>Example 1> >Making polarizing film> Prepare a polyvinyl alcohol film with an average degree of polymerization of 2,400, a degree of saponification of 99.9 mol%, and a thickness of 45 μm. The polyvinyl alcohol film was immersed in a swelling bath (water bath) at 20°C for 30 seconds to swell between rolls with different peripheral speed ratios, and stretched 2.2 times in the conveying direction (swelling step), and then heated at 30°C. In the dyeing bath (an iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 relative to 100 parts by weight of water), the concentration is adjusted so that the iodine concentration of the polarizing film obtained finally becomes 3.60% by weight, while immersed in Among them, dyeing is carried out for 30 seconds, while extending 3.3 times in the conveying direction based on the original polyvinyl alcohol film (a polyvinyl alcohol film that has not been stretched in the conveying direction at all) (dyeing step). Next, the dyed polyvinyl alcohol film was immersed in a cross-linking bath (an aqueous solution with a boric acid concentration of 3.0% by weight and potassium iodide concentration of 3.0% by weight) at 40°C for 28 seconds, and was based on the original polyvinyl alcohol film Extend to 3.6 times in the conveying direction (crosslinking step). Then, the obtained polyvinyl alcohol film was immersed in a 61°C stretching bath (an aqueous solution with a boric acid concentration of 4.0% by weight and potassium iodide concentration of 5.0% by weight) for 60 seconds, and stretched in the conveying direction based on the original polyvinyl alcohol film. After 6.0 times (extension step), immerse in a 35°C washing bath (aqueous solution with a potassium iodide concentration of 2.0% by weight) for 10 seconds (washing step). The washed polyvinyl alcohol film was dried at 40°C for 30 seconds to prepare a polarizing film. The thickness of the polarizing film is 18μm.

[Measurement method of iodine content (weight%) in polarizing film] For the polarizing film, an X-ray fluorescence analyzer (manufactured by Rigaku Corporation, trade name "ZSX-PRIMUS IV", measurement diameter: ψ20 mm) was used, and the iodine concentration (% by weight) was determined by the following formula. Iodine concentration (wt%)=14.474×(fluorescent X-ray intensity)/(film thickness)(kcps/μm) In addition, the coefficient when calculating the concentration will be different depending on the measuring device, but the coefficient can be checked by appropriate Calculated by the volume curve.

…(9)>Making polarizing film> The following aqueous solution is used as the adhesive: a weight ratio of 3:1:4 containing polyvinyl alcohol resin containing acetyl acetyl (average degree of polymerization 1,200, saponification degree 98.5 mol%, acetyl acetyl group) The degree of chemical conversion is 5 mol%), methylol melamine, and a compound having nitroxide radicals or nitroxyl groups represented by the general formula (9). Using this adhesive, a 47μm-thick cellulose triacetate film with a hard coat layer (with a moisture permeability of 342g/(m ² · 24h), manufactured by Konica Minolta, trade name "KC4UYW") was used as a transparent protective film with a roll laminator After bonding to both sides of the polarizing film obtained above, heating and drying are continued in an oven (temperature is 60° C., time is 4 minutes) to produce a polarizing film with transparent protective films bonded on both sides of the polarizing film. The monomer transmittance of the polarizing film is 39.7%. [Chemical formula 9]

…(9)

>Preparation of acrylic adhesives> The monomer mixture containing 99 parts of butyl acrylate and 1 part of 4-hydroxybutyl acrylate was fed into a 4-necked flask equipped with a stirring blade, a thermometer, a nitrogen introduction tube, and a cooler. With respect to 100 parts of the aforementioned monomer mixture (solid content), 0.1 part of 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 parts of ethyl acetate were fed together, and nitrogen was introduced while slowly stirring. After the nitrogen substitution, the liquid temperature in the flask was maintained at around 55°C, and the polymerization reaction was performed for 8 hours to prepare a solution of an acrylic polymer with a weight average molecular weight (Mw) of 1.8 million. Then, with respect to 100 parts of the solid content of the obtained acrylic polymer solution, an isocyanate crosslinking agent (manufactured by Tosoh Corporation, trade name "TAKENATE D110N"," trimethylolpropane/diisocyanate extension Ester adduct) 0.02 parts, and 0.2 parts of silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd., trade name "X-41-1056") to prepare a solution of acrylic adhesive composition. Next, the solution of the acrylic adhesive composition obtained above was applied to the polyethylene terephthalate film treated with a silicone release agent so that the thickness of the adhesive layer after drying became 20 μm (Made by Mitsubishi Chemical Polyester Film, trade name "MRF38", separation film) and dry at 90°C for 1 minute on one side to form an adhesive layer on the surface of the separation film. Then, the adhesive layer formed on the separation film was transferred to one side of the polarizing film produced above, and the polarizing film with the adhesive layer was produced.

>Making an analog video display device (layered body)> The polarizing film with the adhesive layer obtained above is cut into a size of 45×40mm so that the absorption axis of the polarizing film is the long side, and the glass plate (analogous image display unit) is pasted through the adhesive layer, and then the polarizing film On the other side, through an acrylic monomer-free adhesive (manufactured by Nitto Denko Co., Ltd., trade name "LUCIACS CS9868") with a thickness of 200 μm, another glass plate (simulating the front transparent member) was laminated to produce an analog video display device ( Layered body).

[Evaluation of monomer transmittance under high temperature environment] The simulated image display device (laminated body) obtained above was placed in a hot air oven at a temperature of 105°C for 48 hours, and the monomer transmittance (ΔTs) before and after the input (heating) was measured ). The transmittance of the monomer was measured using a spectrophotometer (manufactured by Murakami Color Research Institute Co., Ltd., product name "DOT-3"), and evaluated based on the following criteria. The single transmittance is the Y value obtained by performing visual sensitivity compensation according to the 2 degree field of view (C light source) of JIS Z 8701-1982. In addition, the measurement wavelength is 380 to 700 nm (every 10 nm). The results are listed in Table 1. _{ΔTs (%) = Ts 48 -Ts} 0 Here, Ts ₀ of analog video pre-heating display single transmittance apparatus (laminate) is, Ts ₄₈ into an analog video heated 48 hours means (laminate) is displayed Monomer transmittance. ○: 5≧ΔTs(%)≧0 ×: ΔTs(%)>5, or ΔTs(%)>0

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

…(10)>Example 2>>Making polarizing film, polarizing film, analog image display device (laminate)> When making polarizing film, add the general formula (10) to the two adhesives used in a weight ratio of 4:3 Shown are compounds with nitroxyl radicals or nitroxyl groups and polyvinyl alcohol resin, and potassium hydroxide is added in such a way that it does not affect the curing reaction of the adhesive and is 1:1 in molar ratio with respect to the hindered amine compound To adjust the pH (neutralization), except for the same operation as in Example 1, a polarizing film, a double-sided protective polarizing film, and an analog image display device (laminate) were produced. The monomer transmittance of the polarizing film is 40.0%. [Chemical formula 10]

…(10)

>Example 3> >Production of polarizing film, polarizing film, analog image display device (layered body)> When making a polarizing film, use the compound with nitroxide radical or nitroxyl group represented by general formula (8) in the two adhesives used to replace general formula (9), otherwise follow the example 1 The polarizing film, the double-sided protective polarizing film and the analog image display device (laminated body) were produced by the same operation. The monomer transmittance of the polarizing film is 39.6%.

>Example 4> >Production of polarizing film, polarizing film, analog image display device (layered body)> When making a polarizing film, the adhesive is used in a weight ratio of 7:2:1 containing polyvinyl alcohol resin containing acetyl acetone groups, methylol melamine and the formula (6) with nitroxide radicals or nitrogen The aqueous solution of the compound of the oxy group, except that the same operation as in Example 1, was carried out to produce a polarizing film, a double-sided protective polarizing film, and an analog image display device (laminate). The monomer transmittance of the polarizing film is 39.7%.

>Comparative example 1> >Production of polarizing film, polarizing film, analog image display device (layered body)> When making the polarizing film, the compound with nitroxide radical or nitroxyl group represented by the general formula (9) was not added, except that the polarizing film, the polarizing film and the simulated image display were prepared by the same operation as in Example 1. Device (Laminated body). The monomer transmittance of the polarizing film is 39.6%.

The above-mentioned [Evaluation of monomer transmittance under high temperature environment] was performed using the analog image display devices (layered bodies) of the above-obtained Examples and Comparative Examples. The results are listed in Table 1.

[Table 1]

Claims (6)

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 characteristics of the polarizing film are: The aforementioned polarizing film is formed by adsorbing and oriented iodine on the polyvinyl alcohol film; The aforementioned adhesive layer contains a compound having nitroxyl radicals or nitroxyl groups. The polarizing film of claim 1, wherein the aforementioned compound having nitroxide radicals or nitroxyl groups is an N-oxy compound. The polarizing film of claim 1, wherein the content of the compound having nitroxide radicals or nitroxyl groups in the adhesive layer is 70% by weight or less. A laminated polarizing film, characterized in that the polarizing film according to any one of claims 1 to 3 is attached to an optical layer. An image display panel, characterized in that: the polarizing film of any one of claims 1 to 3 or the laminated polarizing film of claim 4 is attached to the image display unit. An image display device, characterized in that the polarizing film or laminated polarizing film side of the image display panel of claim 5 is provided with a front transparent member.