JP6732157B1 - Polarizing film, laminated polarizing film, image display panel, and image display device - Google Patents

Abstract

A polarizing film in which a transparent protective film is attached to at least one surface of a polarizing film via an adhesive layer, wherein the polarizing film is formed by adsorbing and orienting iodine to a polyvinyl alcohol-based film. The agent layer contains a hindered amine compound, and the hindered amine compound is a water-soluble hindered amine compound that can be dissolved in 1 part by weight or more in 100 parts by weight of water at 25°C. The polarizing film is excellent in the effect of suppressing the decrease in the single transmittance due to the coloring of the polarizing film in a high temperature environment.

Description

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

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

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

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

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

Further, it is specifically disclosed that a water-insoluble HALS (Hindered Amine Light Stabilizer) is mixed with an adhesive containing an epoxy compound in order to enhance the heat resistance of a polarizing plate (Patent Document 4). ..

Special table 2012-516468 gazette JP, 2001-240762, A JP, 2005-338343, A Korean Patent Application Publication No. 10-2015-0114149

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

In view of the circumstances as described above, it is an object of the present invention to provide a polarizing film having an excellent effect of suppressing a decrease in single transmittance due to 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, which are excellent in the effect of suppressing the decrease in the single transmittance due to the coloring of the polarizing film.

That is, the present invention is a polarizing film in which a transparent protective film is attached to at least one surface of a polarizing film via an adhesive layer, and the polarizing film is formed by adsorbing and orienting iodine to a polyvinyl alcohol film. The adhesive layer contains a hindered amine-based compound, and the hindered amine-based compound is a water-soluble hindered amine-based compound capable of dissolving 1 part by weight or more in 100 parts by weight of water at 25° C.

The present invention also relates to a laminated polarizing film in which the polarizing film is attached to an optical layer.

The present invention also relates to an image display panel in which the polarizing film or the laminated polarizing film is attached to an image display cell.

The present invention also 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.

The details of the mechanism of action of the effect of the polarizing film of the present invention are unknown, but it is presumed as follows. However, the present invention may not be construed as being limited to this mechanism of action.

In the polarizing film of the present invention, a transparent protective film is attached to at least one surface of the polarizing film via an adhesive layer, and the adhesive layer is dissolved in 1 part by weight or more with respect to 100 parts by weight of water at 25°C. It contains a water-soluble hindered amine compound. The polarizing film is formed by adsorbing and orienting iodine on a polyvinyl alcohol film. As described in Patent Documents 2 and 3 above, it is generally said that the iodine-based polarizing film is inferior in durability such as heat resistance to the dye-based polarizing film, but the reason is included in the polarizing film. It is presumed that the iodine generated promotes the deterioration phenomenon called polyene formation which occurs in the dehydration reaction of polyvinyl alcohol in a high temperature environment.

On the other hand, when the water-soluble hindered amine-based compound contained in the adhesive layer of the present invention is exposed to a high temperature environment, a part of the hindered amine-based compound is eluted from the adhesive layer and comes close to the adhesive layer. It is presumed that it will permeate the iodine-based polarizing film that is used. In particular, in the image display device including the front transparent member, the polarizing film, and the image display cell provided in this order, the hindered amine-based compound contained in the adhesive layer, when exposed to a high temperature environment, Along with the moisture present inside (moisture present in the pressure-sensitive adhesive layer, adhesive layer, etc.), it moves (stays) inside the image display device, so that part of the hindered amine-based compound easily permeates the iodine-based polarizing film. It is estimated that As a result, it is estimated that the hindered amine-based compound in the polarizing film can efficiently capture the radicals generated in the above-mentioned polyene conversion reaction under a high temperature environment. The decrease in the rate can be suppressed.

<Hindered amine compounds>
The hindered amine compound of the present invention is a water-soluble hindered amine compound that can be dissolved in 1 part by weight or more in 100 parts by weight of water at 25°C. The hindered amine compounds may be used alone or in combination of two or more.

The hindered amine-based compound has a ratio of 2 to 100 parts by weight of water at 25° C. from the viewpoint that a part of the hindered amine-based compound is easily eluted from the adhesive layer and easily penetrates into the iodine-based polarizing film adjacent to the adhesive layer. It is preferable that at least 5 parts by weight can be dissolved, more preferably at least 5 parts by weight with respect to 100 parts by weight of water at 25°C.

In addition, the hindered amine compound has a molecular weight of preferably 1,000 or less, more preferably 500 or less, and further preferably 300 or less, from the viewpoint of being able to efficiently capture the radicals generated in the polyene formation reaction. preferable.

（一般式（１）中、Ｒ^１は、オキシラジカル、水素原子、ヒドロキシ基、または炭素原子数が１〜３０のアルキル基、ヒドロキシアルキル基、ヒドロキシアルコキシ基、もしくはアルコキシ基を表し、Ｒ^２からＲ^５は、独立して、水素原子、または炭素原子数が１〜１０のアルキル基を表し、ｎは０または１を表す。）なお、一般式（１）中の、点線部の左は任意の有機基を示す。The hindered amine compound of the present invention is a secondary amine or tertiary amine in which an alkyl group is substituted on a carbon adjacent to an amino group to sterically protect the amino group, and for example, an organic group having the following structure And a compound having It should be noted that the exemplified compound may include a structure that cannot be dissolved in 1 part by weight or more with respect to 100 parts by weight of water at 25° C., but those skilled in the art can consider the common general knowledge and, therefore, the exemplified compound. However, it can be immediately confirmed whether 1 part by weight or more can be dissolved in 100 parts by weight of water at 25°C.

In (formula (1), R ¹ is oxy radical, a hydrogen atom, a hydroxyl group or an alkyl group having 1 to 30 carbon atoms, a hydroxyalkyl group, hydroxyalkoxy group or an alkoxy group, a R ^2, R ⁵ independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n represents 0 or 1.) In general formula (1), the left side of the dotted line part is arbitrary. Represents an organic group of.

The hindered amine compounds are known compounds and are described, for example, in US Pat. No. 4,619,956, columns 5 to 11 and US Pat. No. 4,839,405, columns 3 to 5. 2,2,6,6-tetraalkylpiperidine compounds, or acid addition salts thereof or complexes of these with metal compounds, as described above.

（一般式（２）中、Ｒ^１は、オキシラジカル、水素原子、ヒドロキシ基、または炭素原子数が１〜３０のアルキル基、ヒドロキシアルキル基、ヒドロキシアルコキシ基、もしくはアルコキシ基を表し、Ｒ^２からＲ^５は、独立して、水素原子、または炭素原子数が１〜１０のアルキル基を表し、Ｒ^６は水素原子、または炭素原子数が１〜１０のアルキル基、アシル基、もしくはアリール基を表し、ｎは０または１を表す。）

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

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

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

In (formula (2), R ¹ is oxy radical, a hydrogen atom, a hydroxyl group or an alkyl group having 1 to 30 carbon atoms, a hydroxyalkyl group, hydroxyalkoxy group or an alkoxy group, a R ^2, R ⁵ independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and R ⁶ is a hydrogen atom or an alkyl group, an acyl group, or an aryl group having 1 to 10 carbon atoms. And n represents 0 or 1.)

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

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

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

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

<Polarizing film>
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, the polarizing film is formed by adsorption adsorption iodine iodine to a polyvinyl alcohol film. The adhesive layer contains the hindered amine compound.

<Polarizing film>
The polarizing film of the present invention is formed by aligning iodine on a polyvinyl alcohol film. As the polyvinyl alcohol (PVA) film, a film having a light-transmitting property in the visible light region and capable of dispersing and adsorbing iodine can be used without particular limitation. Moreover, the PVA-based film, which is usually used as a raw fabric, preferably has a thickness of about 1 to 100 μm, more preferably about 1 to 50 μm.

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

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

The polarizing film can be produced, for example, by dyeing the polyvinyl alcohol-based film by immersing it in an aqueous solution of iodine and stretching the film to 3 to 7 times its original length. If necessary, it can be immersed in an aqueous solution of boric acid, potassium iodide or the like. Further, if necessary, the polyvinyl alcohol film may be immersed in water and washed with water before dyeing. By washing the polyvinyl alcohol-based film with water, it is possible to wash the stains and antiblocking agent on the surface of the polyvinyl alcohol-based film, and by swelling the polyvinyl alcohol-based film, the effect of preventing unevenness such as unevenness of dyeing is also exerted. is there. Stretching may be performed after dyeing with iodine, stretching while dyeing, or stretching and then dyeing with iodine. Stretching can be performed in an aqueous solution of boric acid or potassium iodide, or in a water bath.

The polarizing film preferably has a thickness of about 1 to 50 μm, more preferably about 1 to 25 μm. In particular, in order to obtain a polarizing film having a thickness of 8 μm or less, the above-mentioned JP 2009-098653 A, JP 2012-073580 A, JP 2013-238640 A, JP 4691205 B, and JP A method for producing a thin polarizing film using a laminate including a polyvinyl alcohol-based resin layer formed on a resin base material such as a thermoplastic resin as the polyvinyl alcohol-based film disclosed in Japanese Patent No. 4751481 is disclosed. Applicable.

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

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

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

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

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

In the adhesive layer, the content of the hindered amine compound in the adhesive layer is preferably 70% by weight or less. The adhesive layer is preferably 1% by weight or more, and more preferably 5% by weight or more, in the adhesive layer from the viewpoint of suppressing a decrease in single-body transmittance due to coloring of the polarizing film in a high temperature environment. It is preferably 10% by weight or more, more preferably 60% by weight or less, and further 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 forming the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy and the like is used. Examples of the thermoplastic resin include cellulose ester resins such as triacetyl cellulose, polyester resins such as polyethylene terephthalate and polyethylene naphthalate, polyether sulfone resins, polysulfone resins, polycarbonate resins, nylon and aroma. Polyamide resins such as group polyamides, polyimide resins, polyolefin resins such as polyethylene, polypropylene and ethylene/propylene copolymers, (meth)acrylic resins, cyclo polyolefin resins having a cyclo or norbornene structure (norbornene resins) ), polyarylate-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, and mixtures thereof. Further, the transparent protective film may use a cured layer formed of a thermosetting resin such as a (meth)acrylic resin, a urethane resin, an acryl urethane resin, an epoxy resin, a silicone resin, or an ultraviolet curable resin. Among these, cellulose ester resin, polycarbonate resin, (meth)acrylic resin, cyclic polyolefin resin, and polyester resin are preferable.

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

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

As the transparent protective film, a retardation plate having a front surface retardation of 40 nm or more and/or a thickness direction retardation of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective film, the retardation plate also functions as a transparent protective film, so that the thickness can be reduced.

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

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

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

The polarizing film of the present invention may be such that at least one surface of the polarizing film is bonded to the transparent protective film via the adhesive layer, and the other surface of the polarizing film (the other surface) and the transparent film are transparent. The protective film, or the other surface (the other surface) of the polarizing film and the functional layer are usually attached via a pressure-sensitive adhesive layer or the adhesive layer. Further, an image display cell described below or a front transparent member may be directly bonded to the other surface (the other surface) of the polarizing film via the adhesive layer.

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

As a method of forming the pressure-sensitive adhesive layer, for example, a method of applying the pressure-sensitive adhesive to a release-treated separator or the like, forming a pressure-sensitive adhesive layer by drying, and then transferring it to a polarizing film, or the pressure-sensitive adhesive is polarized. Examples thereof include a method of forming a pressure-sensitive adhesive layer by coating on a film or the like and drying. The thickness of the pressure-sensitive adhesive layer is not particularly limited and is, for example, about 1 to 100 μm, 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 an intervening layer such as a surface modification treatment layer, an easy-adhesive layer, a block layer, and a refractive index adjusting layer. ..

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

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

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

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

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

On one surface or both surfaces of the polarizing film or the laminated polarizing film, an image display cell such as a liquid crystal cell or an organic EL element, and another front transparent member such as a front transparent plate or a touch panel on the viewing side are provided. An adhesive layer for attaching the members may be additionally provided. A pressure-sensitive adhesive layer is suitable as the adhesive layer. The pressure-sensitive adhesive that forms the pressure-sensitive adhesive layer is not particularly limited, but for example, an acrylic polymer, a silicone-based polymer, polyester, polyurethane, polyamide, polyether, or a polymer having a fluorine-based or rubber-based polymer as a base polymer is used. It can be appropriately selected and used. In particular, a pressure-sensitive adhesive containing an acrylic polymer, which has excellent optical transparency, exhibits appropriate wettability, cohesiveness and adhesiveness, and has excellent weather resistance and heat resistance, is preferably used.

The adhesive layer may be attached to one side or both sides of the polarizing film or the laminated polarizing film by an appropriate method. As the attachment of the pressure-sensitive adhesive layer, for example, a method of preparing a pressure-sensitive adhesive solution and directly attaching it to the polarizing film or the laminated polarizing film by an appropriate development method such as a casting method or a coating method, or a separator Examples include a method of forming an adhesive layer on the above and transferring it to the polarizing film or the laminated polarizing film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined depending on the purpose of use, adhesive strength, etc., and is generally 1 to 500 μm, preferably 5 to 200 μm, and more preferably 10 to 100 μm. Thus, the polarizing film or the laminated polarizing film provided with the adhesive layer on at least one surface thereof is referred to as a polarizing film with an adhesive layer or a laminated polarizing film with an adhesive layer.

It is preferable that the exposed surface of the pressure-sensitive adhesive layer is temporarily attached and covered with a separator for the purpose of preventing contamination and the like until it is put into practical use. As a result, the pressure-sensitive adhesive layer can be prevented from being contaminated in the usual handling conditions. Examples of the separator include plastic films, rubber sheets, paper, cloth, non-woven fabrics, nets, foamed sheets and metal foils, and appropriate thin sheets such as laminates thereof, if necessary, silicone-based or long-chain alkyl-based, Those coated with an appropriate release agent such as fluorine-based or molybdenum sulfide are used.

<Image display panel and image display device>
The image display panel of the present invention is one in which the polarizing film or the laminated polarizing film is attached to an image display cell. Further, the image display device of the present invention includes a front transparent member on the polarizing film or laminated polarizing film side (viewing side) of the image display panel.

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

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

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

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

<Example 1>
<Production of polarizing film>
A polyvinyl alcohol film having an average degree of polymerization of 2,400, a degree of saponification of 99.9 mol% and a thickness of 45 μm was prepared. The polyvinyl alcohol film was dipped in a swelling bath (water bath) at 20° C. for 30 seconds between rolls having different peripheral speed ratios and stretched 2.2 times in the transport direction while swelling (swelling step). The iodine concentration of the polarizing film finally obtained in a dyeing bath at 30° C. (an iodine aqueous solution obtained by mixing iodine and potassium iodide in a weight ratio of 1:7 to 100 parts by weight of water) is 3 It is soaked for 30 seconds while adjusting the concentration to be 60% by weight and dyed 3.3 times in the transport direction based on the original polyvinyl alcohol film (polyvinyl alcohol film that has not been stretched in the transport direction) while dyeing. Was stretched (dyeing step). Then, the dyed polyvinyl alcohol film is immersed in a crosslinking bath at 40° C. (an aqueous solution having a boric acid concentration of 3.0% by weight and a potassium iodide concentration of 3.0% by weight) for 28 seconds to obtain the original polyvinyl alcohol. The film was stretched up to 3.6 times in the transport direction based on the film (crosslinking step). Further, the obtained polyvinyl alcohol film was immersed in a stretching bath at 61° C. (an aqueous solution having a boric acid concentration of 4.0% by weight and a potassium iodide concentration of 5.0% by weight) for 60 seconds to obtain the original polyvinyl alcohol. The film was stretched to 6.0 times in the transport direction based on the alcohol film (stretching step), and then immersed in a cleaning bath at 35° C. (aqueous solution having a potassium iodide concentration of 2.0% by weight) for 10 seconds (cleaning). Process). 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 of measuring iodine content (% by weight) in polarizing film]
With respect to the polarizing film, the iodine concentration (% by weight) was obtained using the following formula, using a fluorescent X-ray analyzer (manufactured by Rigaku Corporation, trade name “ZSX-PRIMUS IV”, measurement diameter: ψ20 mm).
Iodine concentration (wt%) = 14.474 x (fluorescent X-ray intensity)/(film thickness) (kcps/μm) Although the coefficient for calculating the concentration varies depending on the measuring device, the coefficient is an appropriate calibration curve. Can be obtained using.

<Production of polarizing film>
As an adhesive, a polyvinyl alcohol resin containing an acetoacetyl group (average polymerization degree: 1,200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 mol%), methylolmelamine, and a general formula (6) An aqueous solution containing a hindered amine compound represented by (3) in a weight ratio of 3:1:4 was used. Using this adhesive, as a transparent protective film on both surfaces of the polarizing film obtained above, a triacetyl cellulose film having a hard coat layer and a thickness of 47 μm (moisture permeability: 342 g/(m ² ·24 h), Konica Minolta Manufactured by the company, "KC4UYW") is pasted with a roll pasting machine, and then dried by heating in an oven (temperature is 60°C, time is 4 minutes), and transparent protective films are pasted on both sides of the polarizing film. The obtained polarizing film was produced. The single transmittance of the polarizing film was 39.7%. The hindered amine compound represented by the following general formula (6) is a compound that dissolves in 1 part by weight or more in 100 parts by weight of water at 25°C.

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

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

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

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

<Example 2>
<Production of Polarizing Film, Polarizing Film, Pseudo Image Display Device (Laminate)>
In the production of the polarizing film, the hindered amine compound represented by the general formula (7) is added to both of the adhesives used so that the weight ratio of the polyvinyl alcohol resin to the adhesive is 4:3 to influence the curing reaction of the adhesives. In the same manner as in Example 1 except that potassium hydroxide was added to the hindered amine compound at a molar ratio of 1:1 to adjust the pH (neutralize) so as not to give By operation, a polarizing film, a double-sided protective polarizing film, and a pseudo image display device (laminate) were produced. The single transmittance of the polarizing film was 40.0%. The hindered amine compound represented by the following general formula (7) is a compound that dissolves in 1 part by weight or more in 100 parts by weight of water at 25°C.

<Example 3>
<Production of Polarizing Film, Polarizing Film, Pseudo Image Display Device (Laminate)>
In the production of the polarizing film, the hindered amine compound represented by the general formula (8) was added to both adhesives used so that the weight ratio with the polyvinyl alcohol resin was 4:3, and the curing reaction of the adhesives was affected. In the same manner as in Example 1 except that hydrochloric acid was added to the hindered amine compound at a molar ratio of 1:1 to adjust the pH (neutralize) so as not to give Then, a polarizing film, a double-sided protective polarizing film, and a pseudo image display device (laminate) were produced. The single transmittance of the polarizing film was 39.9%. The hindered amine compound represented by the following general formula (8) is a compound that dissolves in 1 part by weight or more in 100 parts by weight of water at 25°C.

<Example 4>
<Production of Polarizing Film, Polarizing Film, Pseudo Image Display Device (Laminate)>
In the production of the polarizing film, an aqueous solution containing a polyvinyl alcohol resin containing an acetoacetyl group, methylolmelamine and a hindered amine compound represented by the general formula (6) at a weight ratio of 7:2:1 was used as an adhesive. Other than the above, a polarizing film, a double-sided protective polarizing film, and a pseudo image display device (laminate) were produced by the same operation as in Example 1. The single transmittance of the polarizing film was 39.7%.

<Comparative Example 1>
<Production of Polarizing Film, Polarizing Film, Pseudo Image Display Device (Laminate)>
In the production of the polarizing film, a polarizing film, a polarizing film, and a pseudo image display device (laminated body) were prepared in the same manner as in Example 1, except that the hindered amine compound represented by the general formula (6) was not added. ) Was produced. The single transmittance of the polarizing film was 39.6%.

<Comparative example 2>
<Production of polarizing film, polarizing film, pseudo image display device (laminate)>
In the production of the polarizing film, 35 parts by weight of N-hydroxyethylacrylamide (HEAA), 50 parts by weight of acryloylmorpholine (ACMO) as an adhesive, 5 parts by weight of a photoinitiator “IRGACURE 819” (manufactured by BASF) and the general formula (9) 10 parts by weight of a compound represented by the formula (trade name "ADEKA STAB LA-52", manufactured by ADEKA) is mixed and applied onto a polarizing film so that the thickness of the adhesive layer after curing is 1.0 μm. A polarizing film, a polarizing film, and a pseudo image display device (laminated body) were prepared in the same manner as in Example 1 except that ultraviolet rays were irradiated as active energy rays and the adhesive was cured to produce a polarizing film. ) Was produced. Ultraviolet irradiation is performed using a gallium-encapsulated metal halide lamp, irradiation device: Fusion UV Systems, Inc. Light HAMMER 10, bulb: V bulb, peak illuminance: 1600 mW/cm ² , integrated irradiation amount 1000/mJ/cm ² (wavelength 380 to 440 nm). ) Was used, and the illuminance of ultraviolet rays was measured using a Sola-Check system manufactured by Solatell. The single transmittance of the polarizing film was 39.6%. The hindered amine compound represented by the following general formula (9) is a compound that does not dissolve in 1 part by weight or more in 100 parts by weight of water at 25°C.

Using the above-obtained pseudo image display devices (laminates) of Examples and Comparative Examples, the above [Evaluation of single-body transmittance under high temperature environment] was performed. The results are shown in Table 1.

Claims (6)

A polarizing film in which a transparent protective film is attached to at least one surface of a polarizing film via an adhesive layer,
The polarizing film is formed by adsorption orientation of iodine in a polyvinyl alcohol film,
The adhesive layer contains a hindered amine compound,
The hindered amine compound may be dissolved 1 part by weight or more relative to 100 parts by weight of water of 25 ° C., Ri-soluble hindered amine compound der, and having the general formula (1):

In (formula (1), R ¹ is oxy radical, a hydrogen atom, a hydroxyl group or an alkyl group having 1 to 30 carbon atoms, a hydroxyalkyl group, hydroxyalkoxy group or an alkoxy group, a R ^2, R ⁵ independently represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, and n represents 0 or 1, and is a compound having an organic group represented by
The polarizing film , wherein the content of the hindered amine compound in the adhesive layer is 1% by weight or more . The hindered amine compound is represented by the general formula (2):

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

(In the general formula (3), R ¹ to R ⁵ and n are the same as above, and R ⁷ and R ⁸ are independently a hydrogen atom or an alkyl group having 1 to 10 carbon atoms, Represents an acyl group or an aryl group),
General formula (4):

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

(In the general formula (5), R ¹ to R ⁵ and n are the same as above, and R ¹² is a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, an amino group, an alkoxy group, a hydroxy group. Group or an aryl group), which is one or more compounds selected from the group consisting of compounds represented by the formula (1) . Content of the said hindered amine type compound in the said adhesive bond layer is 70 weight% or less, The polarizing film of Claim 1 or 2 characterized by the above-mentioned. A laminated polarizing film comprising the polarizing film according to any one of claims 1 to 3 bonded to an optical layer. An image display panel, wherein the polarizing film according to any one of claims 1 to 3 or the laminated polarizing film according to claim 4 is attached to an image display cell. An image display device comprising a front transparent member on the polarizing film or laminated polarizing film side of the image display panel according to claim 5 .