TWI839423B - Polarizing film with adhesive layer and image display device - Google Patents

Abstract

A polarizing film with an adhesive layer, comprising a polarizing film and an adhesive layer; The polarizing film with an adhesive layer is characterized in that: The polarizing film has a polarizing element, a transparent protective film only on one side of the polarizing element, and a conductive layer on the other side of the polarizing element via a transparent layer, the transparent layer is directly formed on the polarizing element and has a thickness of less than 10 μm, and the adhesive layer is provided via the conductive layer. Even in the case where a conductive layer is provided on the side of the polarizing element of a single-sided protective polarizing film having a transparent protective film only on one side of the polarizing element, fading of the end of the polarizing element can still be suppressed in a humidified environment.

Description

Polarizing film with adhesive layer and image display device

The present invention relates to a polarizing film with an adhesive layer, and also to an image display panel and an image display device using the polarizing film with an adhesive layer.

For an image display panel, such as a liquid crystal panel used in a liquid crystal display device, a polarizing film is usually laminated on both sides of a liquid crystal unit through an adhesive layer. The liquid crystal unit is formed by a liquid crystal layer arranged between a pair of transparent substrates. On the other hand, when the image display panel is manufactured, when the polarizing film with the adhesive layer is attached to the liquid crystal unit, a release film is peeled off from the adhesive layer of the polarizing film with the adhesive layer, and peeling off the release film will generate static electricity. The static electricity generated in this way will affect, for example, the orientation of the liquid crystal layer inside the liquid crystal display panel, resulting in defects. Therefore, for example, by forming an antistatic layer on the outside of the polarizing film, the generation of static electricity can be suppressed.

In order to suppress the generation of static electricity, for example, an optical film with an antistatic adhesive layer has been proposed, wherein an antistatic layer (conductive layer) containing a water-soluble or water-dispersible conductive polymer is provided on at least one side of an optical film (e.g., a polarizing film), and an adhesive layer is laminated on the antistatic layer (Patent Document 1). In addition, it is also known that adding an ionic compound as an antistatic agent to an adhesive can suppress the generation of static electricity (Patent Document 2).

Prior art documents Patent documents Patent document 1: Japanese Patent Publication No. 2004-338379 Patent document 2: Japanese Patent Publication No. 2009-251281

Problems to be solved by the invention According to the polarizing film with antistatic layer described in patent documents 1 and 2, static electricity generation can be suppressed. However, it is known that when the antistatic layer formed of the conductive polymer described in patent document 1 is directly formed on the polarizing element with a single-sided protective polarizing film, the conductive polymer will have an adverse effect on the polarizing element, and the end of the polarizing element will fade in a humidified environment. It is also known that when the adhesive layer containing antistatic agent described in patent document 2 is applied to the polarizing element with a single-sided protective polarizing film, the antistatic agent will enter the interior of the polarizing element in a humidified environment, causing the end of the polarizing element to fade, thereby reducing the antistatic function of the adhesive layer.

The object of the present invention is to provide a polarizing film with an adhesive layer, which can suppress fading of the end of the polarizing element in a humidified environment even in the case where a conductive layer is provided on the polarizing element side of a single-sided protective polarizing film having a transparent protective film only on one side of the polarizing element.

Furthermore, the object of the present invention is to provide an image display panel and an image display device using the polarizing film having the adhesive layer.

Method for solving the problem After actively and diligently studying and researching to solve the aforementioned problem, the inventors discovered the following polarizing film with an adhesive layer, thereby completing the present invention.

That is, the present invention relates to a polarizing film with an adhesive layer, which has a polarizing film and an adhesive layer; The polarizing film with an adhesive layer is characterized in that: The polarizing film has a polarizing element, a transparent protective film only on one side of the polarizing element, and a conductive layer on the other side of the polarizing element with a transparent layer interposed therebetween, the transparent layer is directly formed on the polarizing element and has a thickness of less than 10 μm, and the adhesive layer is provided with the conductive layer interposed therebetween.

In the polarizing film with the adhesive layer, as the transparent layer, a hardened material containing a forming material of urethane prepolymer can be used, and the urethane prepolymer is a reaction product of an isocyanate compound and a polyol. The isocyanate compound is preferably at least one selected from toluene diisocyanate and diphenylmethane diisocyanate.

In the polarizing film with the adhesive layer, the transparent layer may contain epoxy resin.

In the polarizing film with the adhesive layer, the transparent layer may be made of the following resin composition, which includes: (a) a polymer obtained by polymerizing more than 50 parts by weight of an acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of a monomer represented by the following general formula (1): [Chemical Formula 1] (wherein, X represents a functional group containing at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclohexane, hydroxy, amino, aldehyde and carboxyl groups; ^R1 and ^R2 represent independently a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group which may have a substituent or a heterocyclic group which may have a substituent; and ^R1 and ^R2 may be linked to each other to form a ring); and (b) an epoxy resin; and the content ratio of the aforementioned polymer (a) to the epoxy resin (b) is 95:5 to 60:40 or 40:60 to 1:99 by weight.

The functional group represented by X in the above general formula (1) is preferably a functional group represented by the following general formula (2): General formula (2): Z-Y- (wherein, Z represents a functional group containing at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclohexane, hydroxy, amino, aldehyde and carboxyl groups, and Y represents an organic group).

In the polarizing film with the adhesive layer, the thickness of the conductive layer is preferably less than 1 μm.

In the polarizing film with an adhesive layer, the conductive layer preferably contains a conductive polymer.

In the polarizing film with the adhesive layer, the conductive layer preferably contains at least one selected from polythiophene, polyaniline, and carbon nanotubes.

In the polarizing film with an adhesive layer, the adhesive layer may be formed of an adhesive composition containing a (meth)acrylic polymer (A).

In the polarizing film with an adhesive layer, the adhesive layer may be formed of an adhesive composition containing a (meth)acrylic polymer (A) and an ionic compound (B).

In the polarizing film with an adhesive layer, the (meth)acrylic polymer (A) preferably contains an alkyl (meth)acrylate (a1) and an amide group-containing monomer (a2) as monomer units.

In the polarizing film with an adhesive layer, the amide group-containing monomer (a2) is preferably an N-vinyl lactam-containing monomer.

In the polarizing film with the adhesive layer, the amide group-containing monomer (a2) is preferably contained as a monomer unit in the (meth)acrylic polymer (A) in an amount of 0.1 wt % or more.

In the polarizing film with adhesive layer, the ionic compound (B) is preferably an alkali metal salt, and the surface resistance of the adhesive layer is preferably 1×10 ¹⁰ to 1×10 ¹² Ω/□. In addition, the ionic compound (B) is preferably an organic cation-anion salt, and the surface resistance of the adhesive layer is preferably 1×10 ⁸ to 1×10 ¹⁰ Ω/□.

In the polarizing film with the adhesive layer, the ionic compound (B) is preferably contained in an amount of 0.01 parts by weight or more based on 100 parts by weight of the (meth)acrylic polymer (A).

In the polarizing film with an adhesive layer, the transparent protective film is suitable for using a cellulose resin film or a (meth) acrylic resin film.

The present invention also relates to an image display panel, characterized in that it has the polarizing film with the adhesive layer. The image display panel can be applied to a liquid crystal unit with a built-in touch sensing function having a liquid crystal layer and a touch sensor part, and the polarizing film with the adhesive layer is attached to the adhesive layer.

The present invention also relates to an image display device, which is characterized by having the above-mentioned image display panel.

Effect of the invention The polarizing film used in the polarizing film with an adhesive layer of the present invention is a single-sided protected polarizing film having a transparent protective film only on one side of the polarizing element, which is advantageous from the viewpoint of thinness and low cost. On the other hand, since the side of the single-sided protected polarizing film that does not have a transparent protective film has a conductive layer, static electricity generation can be suppressed. In addition, the conductive layer is provided on the polarizing element via a transparent layer, so the conductive layer will not directly affect the polarizing element, thereby suppressing fading of the end of the polarizing element in a humidified environment.

Furthermore, although an adhesive layer is provided on the conductive layer, when an ionic compound is added to the adhesive layer, the antistatic performance can be improved by the conductive layer and the adhesive layer. Furthermore, even when an ionic compound is added to the adhesive layer, the ionic compound contained in the adhesive layer can be suppressed from segregating to the polarizer by the transparent layer, so that the resistance value of the adhesive layer can be suppressed from increasing even in a humidified environment.

As described above, according to the polarizing film with an adhesive layer of the present invention, a polarizing film with an adhesive layer can be provided, which can suppress the optical reliability degradation of the polarizing element even when a single-sided protective polarizing film is used, is thin and has good optical reliability, and has excellent long-term antistatic properties.

The polarizing film with adhesive layer of the present invention is shown in FIG1 , for example. As shown in FIG1 , the polarizing film with adhesive layer 1 uses a single-sided protective polarizing film 11, which has a polarizer a, a transparent protective film b only on one side of the polarizer a, and a transparent layer c on the other side of the polarizer a. The single-sided protective polarizing film 11 is provided with the transparent layer c, the conductive layer d, and the adhesive layer 21 in sequence. From the viewpoint of suppressing the increase of the moisture content of the polarizer in a high temperature and high humidity environment, the transparent layer c is preferably directly provided on the polarizer a. The transparent layers c and d will be described later.

>Polarizing film with adhesive layer> First, the components constituting the polarizing film with adhesive layer of the present invention are described.

There is no particular limitation on the polarizer, and various polarizers can be used. As polarizers, hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified films of ethylene-vinyl acetate copolymers adsorb dichroic substances such as iodine or dichroic dyes and are uniaxially stretched, as well as polyene oriented films such as dehydrated polyvinyl alcohol or dehydrogenated polyvinyl chloride. Among them, polarizers composed of polyvinyl alcohol films and dichroic substances such as iodine are more suitable. There is no particular limitation on the thickness of these polarizers, which is generally less than about 80μm.

In addition, the polarizer can be a thin polarizer with a thickness of less than 10 μm. From the perspective of thinness, the thickness is preferably 1 to 7 μm. Such a thin polarizer has less thickness variation, better visibility, less dimensional change, and excellent durability. In addition, the thickness of the polarizing film can also be reduced, which is more ideal from these perspectives.

As the material constituting the transparent protective film, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture resistance, isotropy, etc. can be used. Specific examples of the thermoplastic resin include cellulose resins such as cellulose triacetate, polyester resins, polyether resins, polyester resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. In addition, on one side of the polarizer, the transparent protective film is bonded by an adhesive layer, and on the other side, the transparent protective film can use a thermosetting resin or a UV-curing resin such as (meth) acrylic, urethane, acrylic urethane, epoxy, or silicone.

The material of the transparent protective film is preferably a cellulose resin or a (meth) acrylic resin in order to minimize the variation of the surface resistance value of the adhesive layer. In addition, the (meth) acrylic resin is preferably a (meth) acrylic resin having a lactone ring structure. Examples of the (meth) acrylic resin having a lactone ring structure include the (meth) acrylic resin having a lactone ring structure described in Japanese Patent Publication No. 2000-230016, Japanese Patent Publication No. 2001-151814, Japanese Patent Publication No. 2002-120326, Japanese Patent Publication No. 2002-254544, Japanese Patent Publication No. 2005-146084, etc. In particular, cellulose resin is more effective than (meth) acrylic resin in suppressing cracks in polarizers, which is a problem in single-sided protection of polarizing films, and is therefore superior from this point of view.

The surface of the transparent protective film not in contact with the polarizer may be provided with a hard coating layer, an anti-reflection layer, an anti-adhesion layer, a diffusion layer, or even an anti-glare layer.

As long as the adhesive used for bonding the polarizer and the transparent protective film is optically transparent, various adhesives such as water-based, solvent-based, hot melt adhesive, free radical curing type, and cationic curing type can be used without particular limitation, but water-based adhesives or free radical curing type adhesives are more suitable.

>Transparent layer> The following is a detailed description of the transparent layer.

From the perspective of thinning and optical reliability, the thickness of the transparent layer is preferably 10 μm or less, preferably 5 μm or less, more preferably 3 μm or less, more preferably 1.5 μm or less, and more preferably 1 μm or less. If the transparent layer is too thick, the thickness of the polarizing film will become thicker, and there is a risk of reducing the optical reliability of the polarizer. On the other hand, from the perspective of suppressing the variation ratio of the surface resistance value of the adhesive layer to a smaller level, the thickness of the transparent layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, and more preferably 0.3 μm or more.

The material forming the transparent layer can be a material having transparency and capable of suppressing the influence of the conductive layer on the polarizer. The material can be, for example, a material forming a urethane prepolymer (a) which is a reaction product of an isocyanate compound and a polyol.

The isocyanate compound is preferably, for example, a polyfunctional isocyanate compound, and specific examples thereof include polyfunctional aromatic isocyanate compounds, alicyclic isocyanate compounds, aliphatic isocyanate compounds, and dimers thereof.

Examples of the polyfunctional aromatic isocyanate compound include phenyl diisocyanate, 2,4-toluene isocyanate, 2,6-toluene diisocyanate, 2,2'-diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-toluidine diisocyanate, 4,4'-diphenyl ether diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, stilbene diisocyanate, methylene bis-4-phenyl isocyanate, and p-phenyl diisocyanate.

Examples of the polyfunctional alicyclic isocyanate compound include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-diisocyanatomethylcyclohexane, isophorone diisocyanate, hydrodiphenylmethane diisocyanate, hydrostilbene diisocyanate, hydrotoluene diisocyanate, and hydrotetramethylstilbene diisocyanate.

Examples of the polyfunctional aliphatic isocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propyl diisocyanate, 1,3-butyl diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

Examples of the polyfunctional isocyanate compound include those having three or more isocyanate groups such as tris(6-isocyanatohexyl)isocyanurate.

Examples of the polyol include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methane-1,5-pentanediol, 2-butane-2-ethane-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methane-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerol, trihydroxymethylpropane, neopentyletrol, hexanetriol, and polypropylene glycol.

As the aforementioned urethane prepolymer (a), in the present invention, it is preferable to use a rigid structure in which a cyclic structure (benzene ring, cyanurate ring, isocyanurate ring, etc.) accounts for a large proportion in the molecular structure. For example, the aforementioned polyfunctional isocyanate compound can be used alone or in combination of two or more, but from the viewpoint of inhibiting the mixing of moisture into the aforementioned polarizer, an aromatic isocyanate compound is preferred. Other polyfunctional isocyanate compounds can also be used in combination with aromatic isocyanate compounds. Among the aromatic isocyanate compounds, the aforementioned isocyanate compound is particularly preferably at least one selected from toluene diisocyanate and diphenylmethane diisocyanate.

The urethane prepolymer (a) preferably uses trihydroxymethylpropane-tri-toluene isocyanate or trihydroxymethylpropane-tri-diphenylmethane diisocyanate. In addition, the urethane prepolymer (a) is a compound having a terminal isocyanate group, and can be obtained, for example, by mixing an isocyanate compound and a polyol, stirring and reacting them. It is usually preferable to mix the isocyanate compound and the polyol in such a way that the isocyanate group is in excess relative to the hydroxyl group of the polyol.

In addition, the urethane prepolymer (a) may be one in which a protecting group is added to the terminal isocyanate group. The protecting group includes oxime and lactam. The isocyanate group is protected by heating to dissociate the protecting group from the isocyanate group, thereby allowing the isocyanate group to react.

The material for forming the transparent layer may contain, in addition to the aforementioned urethane prepolymer (a), a compound (b) having at least two functional groups having active hydrogen that is reactive with an isocyanate group. The functional group having active hydrogen that is reactive with an isocyanate group may be a hydroxyl group, an amino group, etc. The more the number of functional groups having active hydrogen that the aforementioned compound (b) has, the more reaction points with the isocyanate group of the urethane prepolymer (a) will become, making it easier to form a cured product, so the number of the aforementioned functional groups is preferably 3 or more.

The value obtained by dividing the molecular weight of the compound (b) by the number of functional groups is preferably not more than 350. By defining the relationship between the molecular weight and the number of functional groups as described above, the reactivity of the compound (b) with the isocyanate group of the urethane prepolymer (a) can be ensured.

The molecular weight of the compound (b) is preferably 1000 or less. The molecular weight of the compound (b) is preferably 1000 or less from the viewpoint of compatibility when the compound (b) is prepared in a solution form with the urethane prepolymer (a) to form a material.

Examples of the compound (b) include polyols, polyamines, and compounds having a hydroxyl group and an amino group in the molecule.

Examples of the polyol include difunctional alcohols such as ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methyl-1,5-pentanediol, 2-butyl-2-ethyl-1,3-propanediol, 2,4-diethyl-1,5-pentanediol, 1,2-hexanediol, 1,6-hexanediol, 1,8-octanediol, 1,9-nonanediol, 2-methyl-1,8-octanediol, 1,8-decanediol, octadecanediol, and polypropylene glycol; trifunctional alcohols such as glycerol and trihydroxymethylpropane; tetrafunctional alcohols such as neopentyltol, hexanetriol, and sorbitol; and other examples include adducts obtained by adding alkylene oxides (e.g., propylene oxide) to the above polyols such as polyoxypropyl glyceryl ether, polyoxypropyl trihydroxymethylpropane ether, and polyoxypropyl sorbitol ether.

Examples of the polyamine include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4′-diamine, dimer diamine, and the like.

Examples of the compound having a hydroxyl group and an amino group in the molecule include diamines having a hydroxyl group in the molecule such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine; and alkanolamines such as ethanolamine, diethanolamine, and triethanolamine.

The compound (b) is preferably a polyol from the viewpoint of preventing the optical reliability of the polarizer from being deteriorated, and trihydroxymethyl propane is particularly preferred from the viewpoint of reactivity with the urethane prepolymer (a).

The aforementioned forming material contains the aforementioned urethane prepolymer (a) as a main component. The urethane prepolymer (a) preferably contains 50% by weight or more of the solid content of the forming material.

The blending ratio of the compound (b) to the urethane prepolymer (a) is preferably 5% by weight or more relative to the total 100% by weight (solid content ratio) of the urethane prepolymer (a) and the compound (b). From the perspective of improving film strength, the blending ratio of the compound (b) is preferably 10% by weight or more. On the other hand, if the blending ratio of the compound (b) increases, the optical reliability of the polarizer may be deteriorated. Therefore, the blending ratio of the compound (b) is preferably 80% by weight or less, and more preferably 50% by weight or less.

The aforementioned forming material may further use a reaction catalyst in order to improve the reactivity of the isocyanate group. There is no particular limitation on the reaction catalyst, but a tin-based catalyst or an amine-based catalyst is ideal. One or more reaction catalysts may be used. The amount of the reaction catalyst used is usually 5 parts by weight or less relative to 100 parts by weight of the urethane prepolymer (a). Once the amount of the reaction catalyst is large, the crosslinking reaction rate will become faster and the forming material will foam. However, the use of the foamed forming material cannot obtain sufficient adhesion. Usually, when a reaction catalyst is used, it is preferably 0.01 to 5 parts by weight, and more preferably 0.05 to 4 parts by weight.

A reaction catalyst may be used to improve the reactivity of the isocyanate group. There is no particular limitation on the reaction catalyst, but a tin catalyst or an amine catalyst is ideal. One or more reaction catalysts may be used. The amount of reaction catalyst used is usually 5 parts by weight or less relative to 100 parts by weight of the urethane prepolymer. When the amount of reaction catalyst is large, the crosslinking reaction rate will increase and the formed material will foam. However, the formed material after foaming cannot obtain sufficient adhesion. Usually, when a reaction catalyst is used, it is preferably 0.01 to 5 parts by weight, and more preferably 0.05 to 4 parts by weight.

Tin catalysts may be inorganic or organic, but organic catalysts are preferred. Examples of inorganic tin catalysts include stannous chloride and tin chloride. Organic tin catalysts preferably have at least one of the following organic groups: aliphatic groups and alicyclic groups with skeletons such as methyl, ethyl, ether, and ester groups. Examples include tetra-n-butyltin, tri-n-butyltin acetate, n-butyltin trichloride, trimethyltin hydroxide, dimethyltin dichloride, and dibutyltin dilaurate.

The amine catalyst is not particularly limited. In addition, the amine catalyst may include triethylamine. In addition, the reaction catalyst other than the above may include cobalt cycloalkanoate, benzyltrimethylammonium hydroxide, etc.

The aforementioned forming material is generally used in the form of a solution containing the aforementioned urethane prepolymer (a) and the aforementioned compound (b). The solution may be a solvent system, or an aqueous system such as an emulsion, a colloidal dispersion, or an aqueous solution.

There is no particular limitation on the organic solvent as long as it does not have a functional group having active hydrogen reactive with an isocyanate group and can uniformly dissolve the aforementioned urethane prepolymer (a) and the aforementioned compound (b) constituting the forming material. One organic solvent or a combination of two or more organic solvents can be used. Furthermore, different organic solvents can be used for the aforementioned urethane prepolymer (a) and the aforementioned compound (b), respectively. At this time, the forming material can be prepared by mixing the solutions after preparing each solution. The organic solvent can be further added to the prepared forming material to adjust the viscosity of the forming material. In addition, when the solvent-based solution is dissolved in the organic solvent, it can also contain the alcohols or water listed below as a solvent.

Examples of organic solvents include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic or alicyclic hydrocarbons such as hexane, cyclohexane, and methylcyclohexane; halogens such as 1,2-dichloroethane; ethers such as methyl tertiary butyl ether; ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, and acetylacetone.

In addition, when preparing an aqueous solution, alcohols such as n-butanol and isopropanol, and ketones such as acetone may also be mixed. When preparing an aqueous solution, this may be done by using a dispersant, or by introducing a functional group having low reactivity with an isocyanate group such as a carboxylate, a sulfonate, or a quaternary ammonium salt, or a water-dispersible component such as polyethylene glycol into a urethane prepolymer.

>Epoxy resin> In addition, the material used to form the aforementioned transparent layer may be epoxy resin. Any appropriate epoxy resin may be used as the epoxy resin. Preferably, the epoxy resin may be an epoxy resin having an aromatic epoxy. By using epoxy resin, the time-dependent change of the surface resistance value of the adhesive layer can be suppressed, and the adhesion with the polarizer is better, thereby preventing fading from the end of the polarizer. In addition, when the adhesive layer is formed on the transparent layer, the anchoring force of the adhesive layer can be increased. Examples of the epoxy resin having an aromatic ring include bisphenol-type epoxy resins such as bisphenol A epoxy resin, bisphenol F epoxy resin, and bisphenol S epoxy resin; phenolic-type epoxy resins such as phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; polyfunctional epoxy resins such as glyoxypropyl ether of tetrahydroxyphenylmethane, glyoxypropyl ether of tetrahydroxydiphenyl ketone, and epoxidized polyethylene phenol; naphthol-type epoxy resins, naphthalene-type epoxy resins, and biphenyl-type epoxy resins. Preferably, bisphenol A type epoxy resin, biphenyl type epoxy resin, and bisphenol F type epoxy resin can be used. By using these epoxy resins, fading from the end of the polarizer can be further prevented. The epoxy resin can be used alone or in combination of two or more.

The weight average molecular weight (Mw) of the epoxy resin is preferably 20,000 or more, preferably 30,000 or more, and more preferably 37,000 or more. When the weight average molecular weight of the epoxy resin is within the above range, fading from the end of the polarizer can be further prevented. The weight average molecular weight can be measured by GPC, for example.

In addition, the material forming the aforementioned transparent layer may be, for example, a composition comprising a polymer (a) (hereinafter also referred to as polymer (a)) and an epoxy resin (b), wherein the polymer (a) is obtained by polymerizing more than 50 parts by weight of an acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of a monomer represented by the following general formula (1). The content ratio of the aforementioned polymer (a) to the epoxy resin (b) is preferably 95:5 to 60:40, or 40:60 to 1:99 in terms of weight ratio. [Chemical Formula 2] (wherein, X represents a functional group containing at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclohexane, hydroxy, amino, aldehyde and carboxyl groups; ^R1 and ^R2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent; and ^R1 and ^R2 may be linked to each other to form a ring).

The ratio of the polymer (a) to the epoxy resin (b) in the above composition is 95:5 to 60:40, or 40:60 to 1:99 by weight. By having the ratio of the polymer (a) to the epoxy resin (b) in the above range, a transparent layer resin composition can be obtained that can suppress the change in the surface resistance of the adhesive layer over time, has better adhesion to the polarizer, and can prevent fading from the end of the polarizer. In addition, by having the ratio of the polymer (a) to the epoxy resin (b) in the above range, when an adhesive layer is formed on the transparent layer, the anchoring force of the adhesive layer can be increased. As a result, a polarizing plate (single-sided protective polarizing film with transparent layer) can be obtained that takes into account both the adhesion between the polarizing element and the transparent layer and the anchoring force with the adhesive layer formed on the transparent layer. The content ratio of the polymer (a) to the epoxy resin (b) is preferably 95:5 to 80:20 or 20:80 to 5:95 by weight, and more preferably 90:10 to 70:30 or 30:70 to 10:90. The closer the content ratio of the polymer (a) to the epoxy resin (b) is to equal parts (50:50), the greater the risk of whitening of the protective layer.

>Polymer (a)> The aforementioned polymer (a) can be obtained by polymerizing greater than 50 parts by weight of an acrylic monomer and greater than 0 parts by weight and less than 50 parts by weight of a monomer represented by the aforementioned general formula (1).

The aforementioned polymer (a) has a structure represented by the following formula. By polymerizing the monomer represented by the aforementioned general formula (1) and the acrylic monomer component, the polymer (a) may have a substituent containing boron in the side chain (for example, a repeating unit of k in the following formula). Thereby, the adhesion between the polarizer and the layer (transparent layer) formed using the aforementioned resin composition can be improved. The substituent containing boron can be contained in a connected manner to the polymer or can be contained randomly. The aforementioned polymer (a) can be used alone or in combination of two or more. [Chemical Formula 3] (wherein, R ⁶ represents an arbitrary functional group, and j and k represent integers greater than 1).

The weight average molecular weight of the polymer (a) is preferably 10,000 or more, preferably 20,000 or more, more preferably 35,000 or more, and particularly preferably 50,000 or more. Furthermore, the weight average molecular weight of the polymer (a) is preferably 250,000 or less, preferably 200,000 or less, and more preferably 150,000 or less. By having the weight average molecular weight of the polymer (a) be within the above range, the crack resistance of the layer (transparent layer) formed using the resin composition can be improved. The weight average molecular weight can be measured, for example, by GPC (solvent: dimethylformamide (DMF)).

The glass transition temperature of the polymer (a) is preferably 50°C or higher, preferably 60°C or higher, and more preferably 80°C or higher. The glass transition temperature of the polymer (a) is preferably 300°C or lower. When the glass transition temperature is within the above range, the crack resistance of the layer (transparent layer) formed using the resin composition can be improved.

The polymer (a) can be obtained by polymerizing a monomer composition comprising more than 50 parts by weight of an acrylic monomer, more than 0 parts by weight and less than 50 parts by weight of a monomer represented by the general formula (1), a polymerization initiator, and any other monomers by any appropriate polymerization method. The polymerization method can be preferably solution polymerization. By polymerizing the polymer (a) by solution polymerization, a polymer with a higher molecular weight can be obtained.

≪Acrylic monomer≫ Any appropriate acrylic monomer can be used as the acrylic monomer. For example, (meth)acrylate monomers having a linear or branched structure and (meth)acrylate monomers having a ring structure can be cited. In this specification, (meth)acrylic acid means acrylic acid and/or methacrylic acid.

Examples of (meth)acrylate monomers having a linear or branched chain structure include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, isopropyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, tertiary butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and 2-hydroxyethyl (meth)acrylate. Methyl (meth)acrylate is preferably used. The (meth)acrylate monomers may be used alone or in combination of two or more.

Examples of the (meth)acrylate monomer having a ring structure include cyclohexyl (meth)acrylate, benzyl (meth)acrylate, isoborneol (meth)acrylate, 1-adamantyl (meth)acrylate, dicyclopentenyl (meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate, dicyclopentyl (meth)acrylate, biphenyl (meth)acrylate, o-biphenyloxyethyl (meth)acrylate, o-biphenyloxyethoxyethyl (meth)acrylate, m-biphenyloxyethyl acrylate, p-biphenyloxyethyl (meth)acrylate. , o-biphenyloxy-2-hydroxypropyl (meth)acrylate, p-biphenyloxy-2-hydroxypropyl (meth)acrylate, m-biphenyloxy-2-hydroxypropyl (meth)acrylate, N-(meth)acryloyloxyethyl-o-biphenyl = carbamate, N-(meth)acryloyloxyethyl-p-biphenyl = carbamate, N-(meth)acryloyloxyethyl-m-biphenyl = carbamate, o-phenylphenol epoxypropyl ether acrylate and other biphenyl monomers, triphenyl (meth)acrylate, o-triphenyloxyethyl (meth)acrylate, etc. Preferably, 1-adamantyl (meth)acrylate and dicyclopentyl (meth)acrylate can be used. By using these monomers, a polymer with a high glass transition temperature can be obtained. These monomers can be used alone or in combination of two or more. In the present specification, the term "(meth)acryl" refers to an acryl group and/or a methacryl group.

In addition, a silsesquioxane compound having a (meth)acryloyl group may be used in place of the above-mentioned (meth)acrylate monomer. By using a silsesquioxane compound, an acrylic polymer having a high glass transition temperature can be obtained. Silsesquioxane compounds are known to have various skeleton structures such as cage structures, ladder structures, random structures, etc. Silsesquioxane compounds may have only one of these structures or may have two or more. Silsesquioxane compounds may be used alone or in combination of two or more.

Silsesquioxane compounds having (meth)acryloyl groups may be MAC grade and AC grade of the SQ series of Toa Gosei Co., Ltd. MAC grade is a silsesquioxane compound having a methacryloyl group, and specific examples include MAC-SQ TM-100, MAC-SQ SI-20, and MAC-SQ HDM. AC grade is a silsesquioxane compound having an acryl group, and specific examples include AC-SQ TA-100 and AC-SQ SI-20.

The acrylic monomer may be used in an amount of more than 50 parts by weight. The acrylic monomer is used in an amount such that the total amount of the acrylic monomer and the monomer represented by the general formula (1) may be 100 parts by weight.

≪Monomer represented by general formula (1)≫ By using the monomer represented by general formula (1), a boron-containing substituent can be introduced into the side chain of the polymer (a). Therefore, the adhesion between the polarizer composed of PVA-based resin and the layer (transparent layer) formed using the aforementioned resin composition can be improved. In addition, the water resistance of the layer (transparent layer) formed using the aforementioned resin composition itself is also improved, and fading from the end of the polarizer can be prevented. The monomer can be used alone or in combination of two or more. [Chemical formula 4] (wherein, X represents a functional group containing at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclohexane, hydroxy, amino, aldehyde and carboxyl groups; ^R1 and ^R2 each independently represent a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group which may have a substituent, or a heterocyclic group which may have a substituent; and ^R1 and ^R2 may be linked to each other to form a ring).

The above-mentioned aliphatic alkyl group may include a linear or branched alkyl group having 1 to 20 carbon atoms which may have a substituent, a cyclic alkyl group having 3 to 20 carbon atoms which may have a substituent, and an alkenyl group having 2 to 20 carbon atoms. The above-mentioned aryl group may include a phenyl group having 6 to 20 carbon atoms which may have a substituent, a naphthyl group having 10 to 20 carbon atoms which may have a substituent, and the like. The heterocyclic group may include a 5-membered cyclic group or a 6-membered cyclic group containing at least one heteroatom which may have a substituent. In addition, ^R1 and ^R2 may be linked to each other to form a ring. ^R1 and ^R2 are preferably hydrogen atoms or linear or branched alkyl groups having 1 to 3 carbon atoms, and are more preferably hydrogen atoms.

The reactive group contained in the functional group represented by X is at least one selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclobutylene, hydroxy, amino, aldehyde and carboxyl. Preferably, the reactive group is (meth)acryl and/or (meth)acrylamide. By having such reactive groups, the adhesion between the polarizer and the layer (transparent layer) formed using the above-mentioned resin composition can be improved.

In one embodiment, the functional group represented by X is preferably a functional group represented by the following general formula (2): General formula (2): Z-Y- (wherein, Z represents a functional group containing at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclohexane, hydroxy, amino, aldehyde and carboxyl groups, and Y represents an organic group). The aforementioned organic group specifically refers to an organic group having 1 to 20 carbon atoms which may have a substituent, and more specifically includes a linear or branched alkylene group having 1 to 20 carbon atoms which may have a substituent, a cyclic alkylene group having 3 to 20 carbon atoms which may have a substituent, a phenylene group having 6 to 20 carbon atoms which may have a substituent, and a naphthylene group having 10 to 20 carbon atoms which may have a substituent.

Specifically, the following compounds can be used as the monomer represented by the general formula (1). [Chemical Formula 5]

Examples of the monomer represented by the general formula (1) include, in addition to the compounds exemplified above, esters of (meth)acrylic acid esters and boric acid, such as esters of hydroxyethylacrylamide and boric acid, esters of hydroxymethylacrylamide and boric acid, esters of hydroxyethyl acrylate and boric acid, and esters of hydroxybutyl acrylate and boric acid.

The monomer represented by the general formula (1) can be used in an amount greater than 0 parts by weight and less than 50 parts by weight. It is preferably greater than 0.01 parts by weight and less than 50 parts by weight, more preferably 0.05 parts by weight to 20 parts by weight, and more preferably 0.1 parts by weight to 10 parts by weight. If the monomer content is greater than 50 parts by weight, fading from the end is likely to occur.

≪Polymerization initiator≫ Any appropriate polymerization initiator can be used as the polymerization initiator. Examples include peroxides such as benzoyl peroxide, lauryl peroxide, and sodium peroxide; hydrogen peroxides such as tertiary butyl hydroperoxide and isopropylbenzene hydroperoxide; and azo compounds such as azobisisobutyronitrile. The polymerization initiator may be used alone or in combination of two or more.

The content of the polymerization initiator can be any appropriate amount. The content of the polymerization initiator is preferably 0.1 to 5 parts by weight, more preferably 0.3 to 2 parts by weight.

≪Polymerization method≫ As mentioned above, the polymer (a) can be preferably obtained by solution polymerization of monomer components such as acrylic monomers and monomers represented by general formula (1). Any appropriate solvent can be used as the solvent used for solution polymerization. Examples include water; alcohols such as methanol, ethanol, and isopropanol; aromatic or aliphatic hydrocarbons such as benzene, toluene, xylene, cyclohexane, and n-hexane; ester compounds such as ethyl acetate; ketone compounds such as acetone and methyl ethyl ketone; cyclic ether compounds such as tetrahydrofuran and dioxane, etc. Such solvents can be used alone or in combination of two or more. In addition, an organic solvent and water can also be used together.

The polymerization reaction can be carried out at any appropriate temperature and time. For example, the polymerization reaction can be carried out at a temperature in the range of 50°C to 100°C, preferably in the range of 60°C to 80°C. The reaction time is, for example, 1 hour to 8 hours, preferably 3 hours to 5 hours.

>Epoxy resin (b)> Any appropriate epoxy resin can be used as the epoxy resin (b). Preferably, an epoxy resin having an aromatic epoxy group can be used as the epoxy resin (b). By using an epoxy resin having an aromatic epoxy group as the epoxy resin (b), a resin composition for a transparent layer can be obtained that has better adhesion to the polarizer and can prevent fading from the end of the polarizer. In addition, when an adhesive layer is formed on the transparent layer, the anchoring force of the adhesive layer can be increased. Examples of the epoxy resin having an aromatic ring include bisphenol-type epoxy resins such as bisphenol A epoxy resin, bisphenol F epoxy resin, and bisphenol S epoxy resin; phenolic-type epoxy resins such as phenol novolac epoxy resin, cresol novolac epoxy resin, and hydroxybenzaldehyde phenol novolac epoxy resin; polyfunctional epoxy resins such as glyoxypropyl ether of tetrahydroxyphenylmethane, glyoxypropyl ether of tetrahydroxydiphenyl ketone, and epoxidized polyethylene phenol; naphthol-type epoxy resins, naphthalene-type epoxy resins, and biphenyl-type epoxy resins. Preferably, bisphenol A type epoxy resin, biphenyl type epoxy resin, and bisphenol F type epoxy resin can be used. By using these epoxy resins, fading from the end of the polarizer can be further prevented. The epoxy resin can be used alone or in combination of two or more.

The weight average molecular weight (Mw) of the epoxy resin (b) is preferably 20,000 or more, preferably 30,000 or more, and more preferably 37,000 or more. When the weight average molecular weight of the epoxy resin (b) is within the above range, fading from the end of the polarizer can be further prevented. The weight average molecular weight can be measured by GPC, for example.

>Other components> The resin composition for the transparent layer may contain any other appropriate components in addition to the aforementioned epoxy resin, the aforementioned polymer (a) and the epoxy resin (b). Other components may include, for example, solvents and additives. The solvent may be a solvent that can be used for solution polymerization of the aforementioned polymer (a), or other solvents may be used. Other solvents may be ethyl acetate, toluene, methyl ethyl ketone, cyclopentanone, etc. These solvents may be used alone or in combination of two or more.

Any appropriate additive may be used as the additive. Examples thereof include surfactants, ultraviolet light absorbers, antioxidants, and thickeners. The additive may be used alone or in combination of two or more. The additives may be used in any appropriate amount.

>Method for preparing the resin composition for the transparent layer> The resin composition for the transparent layer can be prepared by any appropriate method. For example, it can be prepared by mixing the polymer (a), the epoxy resin (b) and any appropriate additives as required in any appropriate solvent. In addition, when the polymer (a) is polymerized by solution polymerization, the epoxy resin (b) and any appropriate additives can be added to the polymerization solution of the polymer (a) and mixed to prepare the transparent layer.

In addition to the material containing the aforementioned urethane prepolymer (a), the material containing the aforementioned epoxy resin, and the material comprising the composition of the aforementioned polymer (a) and the epoxy resin (b), the material forming the transparent layer may include, for example, a cyanoacrylate-based material, an epoxy-based material, a urethane acrylate-based material, and the like.

The formation of the transparent layer can be appropriately selected according to the type of the aforementioned forming material. For example, the transparent layer can be obtained in the form of a coated layer by coating the forming material on a polarizer, etc. and then curing the material. Generally speaking, the transparent layer is formed by drying the material at about 30 to 100°C, preferably at 50 to 80°C for about 0.5 to 15 minutes after the coating. In addition, when the aforementioned forming material contains an isocyanate component, in order to promote the reaction, an annealing treatment can be performed at about 30 to 100°C, preferably at 50 to 80°C for about 0.5 to 24 hours.

>Conductive layer> From the perspective of surface resistance stability and adhesion to the adhesive layer 21, the thickness of the conductive layer d is preferably less than 1 μm, preferably 0.01 to 0.5 μm, more preferably 0.01 to 0.2 μm, and more preferably 0.01 to 0.1 μm. Furthermore, from the perspective of antistatic performance, the surface resistance of the conductive layer d is preferably 1×10 ⁸ to 1×10 ¹² Ω/□, preferably 1×10 ⁸ to 1×10 ¹¹ Ω/□, and more preferably 1×10 ⁸ to 1×10 ¹⁰ Ω.

The conductive layer can be formed by various antistatic agent compositions. The antistatic agent forming the conductive layer can use an ionic surfactant system, a conductive polymer, conductive microparticles, carbon nanotubes, etc.

From the viewpoint of optical properties, appearance, antistatic effect and stability of the antistatic effect when heated and moistened, conductive polymers and carbon nanotubes are preferably used in the antistatic agents. Conductive polymers such as polyaniline and polythiophene are particularly suitable. Conductive polymers that are soluble in organic solvents, water-soluble, or water-dispersible can be used appropriately, but water-soluble conductive polymers or water-dispersible conductive polymers are preferably used. Because water-soluble conductive polymers or water-dispersible conductive polymers can be used to prepare the coating liquid for forming the antistatic layer into an aqueous solution or an aqueous dispersion, the coating liquid does not need to use a non-aqueous organic solvent and can suppress the deterioration of the optical thin film substrate due to the organic solvent. In addition, the aqueous solution or the aqueous dispersion may contain an aqueous solvent other than water. Examples of alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, di-butanol, tertiary butanol, n-pentanol, iso-pentanol, di-pentanol, tertiary pentanol, 1-ethyl-1-propanol, 2-methyl-1-butanol, n-hexanol, and cyclohexanol.

In addition, the water-soluble conductive polymers or water-dispersible conductive polymers such as polyaniline and polythiophene preferably have hydrophilic functional groups in the molecule. Examples of the hydrophilic functional groups include sulfonic acid groups, amino groups, amide groups, imino groups, quaternary ammonium salt groups, hydroxyl groups, hydroxyl groups, hydrazine groups, carboxyl groups, sulfate groups, phosphate groups, or salts thereof. Since the molecules have hydrophilic functional groups, they can be easily dissolved in water or easily dispersed in water in the form of microparticles, and the water-soluble conductive polymers or water-dispersible conductive polymers can be easily prepared.

Examples of commercially available water-soluble conductive polymers include polyaniline sulfonic acid (manufactured by Mitsubishi Rayon Co., Ltd., weight average molecular weight of 150,000 in terms of polystyrene) and examples of commercially available water-dispersible conductive polymers include polythiophene-based conductive polymers (manufactured by Nagase ChemteX Co., trade name Denatron series).

In addition, as for the formation material of the conductive layer, a binder component may be added together with the antistatic agent for the purpose of improving the film formation of the antistatic agent and the adhesion to the optical film. When the antistatic agent is a water-based material of a water-soluble conductive polymer or a water-dispersible conductive polymer, a water-soluble or water-dispersible binder component is used. Examples of binders include The binder may be a oxazoline polymer, a polyurethane resin, a polyester resin, an acrylic resin, a polyether resin, a cellulose resin, a polyvinyl alcohol resin, an epoxy resin, a polyvinyl pyrrolidone, a polystyrene resin, polyethylene glycol, pentaerythritol, etc. In particular, a polyurethane resin, a polyester resin, and an acrylic resin are preferred. One or more of these binders may be used appropriately according to the application.

The amount of antistatic agent and adhesive used depends on their types, but it is best to control the surface resistance of the resulting conductive layer to 1×10 ⁸ ~1×10 ¹² Ω/□.

>Adhesive layer> The adhesive layer is formed by an adhesive. Various adhesives can be used as the adhesive, such as rubber adhesives, acrylic adhesives, silicone adhesives, urethane adhesives, vinyl alkyl ether adhesives, polyvinyl pyrrolidone adhesives, polyacrylamide adhesives, cellulose adhesives, etc. The adhesive base polymer can be selected according to the type of the adhesive. Among the adhesives, acrylic adhesives are preferably used from the viewpoints of good optical transparency, exhibiting appropriate wettability, cohesion and adhesion, and excellent weather resistance and heat resistance.

The acrylic adhesive is prepared from an adhesive composition containing a (meth)acrylic polymer (A). The adhesive composition is described below.

The (meth)acrylic polymer (A) contains an alkyl (meth)acrylate (a1) as a main component as a monomer unit. In addition, (meth)acrylate means acrylate and/or methacrylate, and (meth) in the present invention also has the same meaning.

The (meth)acrylic acid alkyl ester constituting the main skeleton of the (meth)acrylic polymer (A) may be a linear or branched alkyl group having 1 to 18 carbon atoms. For example, the alkyl group may be a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a pentyl group, a hexyl group, a heptyl group, a 2-ethylhexyl group, an isooctyl group, a nonyl group, a decyl group, an isodecyl group, a dodecyl group, an isomyristyl group, a lauryl group, a tridecyl group, a pentadecyl group, a hexadecyl group, a heptadecanyl group, an octadecyl group, etc. These groups may be used alone or in combination. The average carbon number of these alkyl groups is preferably 3 to 9.

The weight ratio of the alkyl (meth)acrylate (a1) as a monomer unit in the weight ratio of the total monomers (100 weight %) constituting the (meth)acrylic polymer (A) is preferably 70 weight % or more. The weight ratio of the alkyl (meth)acrylate (a1) can be considered as the remainder of other copolymerized monomers. It is preferable to set the weight ratio of the alkyl (meth)acrylate (a1) within the above range in terms of ensuring adhesion.

In order to improve adhesion and heat resistance, in addition to the monomer units of the aforementioned alkyl (meth)acrylate (a1), one or more copolymerizable monomers having an unsaturated double bond such as a (meth)acrylic group or a vinyl group may be introduced into the aforementioned (meth)acrylic polymer (A) by copolymerization.

The copolymerizable monomers include functional group-containing monomers such as amide group-containing monomers, carboxyl group-containing monomers, and hydroxyl group-containing monomers. Among them, the amide group-containing monomer (a2) is suitable for the case of mixing with the ionic compound (B) described later.

In the adhesive composition for forming the above-mentioned adhesive layer, when there is an amide group introduced into the side chain of the (meth)acrylic polymer (A) of the base polymer, the presence of the amide group can suppress the surface resistance value of the adhesive layer adjusted by doping the ionic compound (B) from changing and increasing significantly even in a humidified environment, thereby maintaining it within the range of the desired value, which is preferred. We believe that the presence of the amide group introduced into the side chain of the (meth)acrylic polymer (A) as a functional group of the comonomer can improve the compatibility between the (meth)acrylic polymer (A) and the ionic compound (B).

Furthermore, when the adhesive layer has an amide group introduced into the side chain of the (meth) acrylic polymer (A) of the base polymer, the durability to glass and transparent conductive layer (ITO layer, etc.) is good, and peeling or convexity can be suppressed when attached to a liquid crystal panel. Moreover, the durability can still be satisfied in a humidified environment (after a humidified reliability test).

The amide group-containing monomer (a2) is a compound containing an amide group in its structure and containing a polymerizable unsaturated double bond such as a (meth)acrylamide group or a vinyl group. Specific examples of the amide group-containing monomer (a2) include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N-butyl(meth)acrylamide, N-hexyl(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, N-hydroxymethyl-N-propane(meth)acrylamide, aminomethyl (Meth)acrylamide, aminoethyl (meth)acrylamide, methyl (meth)acrylamide, ethyl (meth)acrylamide and other acrylamide monomers; N-(meth)acryloyl fluorine, N-(meth)acrylpiperidine, N-(meth)acrylpyrrolidine and other N-acryl heterocyclic monomers; N-vinyl pyrrolidone, N-vinyl-ε-caprolactam and other N-vinyl lactam-containing monomers, etc. Amide group-containing monomers (a2) are preferred in terms of suppressing the increase of surface resistance over time (especially in a humidified environment) and satisfying durability. Among the amide-containing monomers (a2), N-vinyl lactam-containing monomers are particularly preferred because they can suppress the increase in surface resistance over time (especially in a humidified environment) and meet the durability requirements for the transparent conductive layer (touch sensor layer). In addition, although not exemplified above, amide-containing monomers having a hydroxyl group tend to have increased conductivity when combined with an ionic compound (B), and if the usage ratio is too high, problems may arise in terms of anchoring force with the polarizing film (optical film) and workability with the transparent conductive layer (touch sensor layer), so they are not suitable for use.

From the viewpoint of suppressing the increase of the surface resistance value over time (especially in a humidified environment), the aforementioned weight ratio of the amide group-containing monomer (a2) is preferably 0.1 weight % or more. The aforementioned weight ratio is preferably 0.3 weight % or more, and more preferably 0.5 weight % or more. On the other hand, if the aforementioned weight ratio is too large, the anchoring property to the substrate film such as the polarizing film tends to be reduced, so the aforementioned weight ratio is preferably 35 weight % or less, preferably 30 weight % or less, and more preferably 25 weight % or less.

The carboxyl group-containing monomer is a compound containing a carboxyl group and a polymerizable unsaturated double bond such as a (meth)acrylic acid group or a vinyl group in its structure. Specific examples of the carboxyl group-containing monomer include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, crotonic acid, etc. Among the above carboxyl group-containing monomers, acrylic acid is preferred from the viewpoints of copolymerizability, price, and adhesive properties.

A hydroxyl-containing monomer is a compound containing a hydroxyl group in its structure and a polymerizable unsaturated double bond such as a (meth)acryloyl group or a vinyl group. Specific examples of hydroxyl-containing monomers include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, 12-hydroxylauryl (meth)acrylate and other hydroxyalkyl (meth)acrylates or (4-hydroxymethylcyclohexyl)-methacrylate. From the viewpoint of durability, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred among the above-mentioned hydroxyl-containing monomers, and 4-hydroxybutyl (meth)acrylate is particularly preferred.

When the adhesive composition contains a crosslinking agent, carboxyl-containing monomers and hydroxyl-containing monomers will become reaction sites with the crosslinking agent. Carboxyl-containing monomers and hydroxyl-containing monomers have good intermolecular reactivity with the crosslinking agent, so they are suitable for improving the cohesion and heat resistance of the resulting adhesive layer. In addition, from the perspective of both durability and workability, carboxyl-containing monomers are more ideal, while from the perspective of workability, hydroxyl-containing monomers are more ideal.

The weight ratio of the carboxyl group-containing monomer is preferably 2% by weight or less, and preferably 0.01 to 2% by weight, more preferably 0.05 to 1.5% by weight, more preferably 0.1 to 1% by weight, and most preferably 0.1 to 0.5% by weight. It is preferred to set the weight ratio of the carboxyl group-containing monomer to 0.01% by weight or more from the perspective of durability. On the other hand, it is not preferred to set the weight ratio of the carboxyl group-containing monomer to more than 2% by weight from the perspective of workability.

The weight ratio of the hydroxyl-containing monomer is preferably 3% by weight or less, and preferably 0.01 to 3% by weight, more preferably 0.1 to 2% by weight, and more preferably 0.2 to 2% by weight. From the perspective of the crosslinked adhesive layer, durability, or adhesive properties, the weight ratio of the hydroxyl-containing monomer is preferably 0.01% by weight or more. On the other hand, when it exceeds 3% by weight, it is not suitable from the perspective of durability.

In addition, as the copolymer monomer, for example, an aromatic ring-containing (meth)acrylate can be used. The aromatic ring-containing (meth)acrylate is a compound containing an aromatic ring structure and a (meth)acryloyl group in its structure. Examples of the aromatic ring include a benzene ring, a naphthalene ring, and a biphenyl ring.

Specific examples of aromatic ring-containing (meth)acrylates include benzyl (meth)acrylate, phenyl (meth)acrylate, o-phenylphenol (meth)acrylate, phenoxy (meth)acrylate, phenoxyethyl (meth)acrylate, phenoxypropyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, ethylene oxide-modified nonylphenol (meth)acrylate, ethylene oxide-modified cresol (meth)acrylate, phenol ethylene oxide-modified (meth)acrylate, 2-hydroxy- Those having a benzene ring, such as 3-phenoxypropyl (meth)acrylate, methoxybenzyl (meth)acrylate, chlorobenzyl (meth)acrylate, cresyl (meth)acrylate, polystyrene (meth)acrylate; those having a naphthyl ring, such as hydroxyethylated β-naphthol acrylate, 2-naphthol ethyl (meth)acrylate, 2-naphthyloxyethyl acrylate, 2-(4-methoxy-1-naphthyloxy)ethyl (meth)acrylate; those having a biphenyl ring, such as biphenyl (meth)acrylate.

From the viewpoint of adhesion and durability, the aromatic ring-containing (meth)acrylate is preferably benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, and particularly phenoxyethyl (meth)acrylate.

The weight ratio of the aromatic ring-containing (meth)acrylate is preferably 25% by weight or less, and preferably 3 to 25% by weight, preferably 10 to 22% by weight, and more preferably 14 to 20% by weight. When the weight ratio of the aromatic ring-containing (meth)acrylate is 3% by weight or more, it is preferred from the perspective of suppressing uneven display. On the other hand, if it exceeds 25% by weight, the suppression of uneven display is insufficient, and there is a tendency for durability to decrease.

Specific examples of other copolymer monomers other than the above include monomers containing anhydride groups such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; monomers containing sulfonic acid groups such as allyl sulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, and sulfopropyl (meth)acrylate; and monomers containing phosphate groups such as 2-hydroxyethylacryloyl phosphate.

Examples of monomers for the purpose of modification include alkylaminoalkyl (meth)acrylates such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and tertiary butylaminoethyl (meth)acrylate; alkoxyalkyl (meth)acrylates such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; N-(meth)acryloyloxymethylenesuccinimide or N-(meth)acryloyl-6-oxyhexamethylenesuccinimide, N-(meth)acryloyloxymethylenesuccinimide; Succinimide monomers such as succinimide (acryloyl-8-oxyoctamethylene succinimide) and the like; maleimide monomers such as N-cyclohexylmaleimide, N-isopropylmaleimide, N-laurylmaleimide, or N-phenylmaleimide; iconimide monomers such as N-methyliconimide, N-ethyliconimide, N-butyliconimide, N-octyliconimide, N-2-ethylhexyliconimide, N-cyclohexyliconimide, and N-lauryliconimide; and the like.

Furthermore, the modified monomer may also include vinyl monomers such as vinyl acetate and vinyl propionate; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy group-containing (meth)acrylates such as glycidyl (meth)acrylate; glycol (meth)acrylates such as polyethylene glycol (meth)acrylate, polypropylene glycol (meth)acrylate, methoxyethylene glycol (meth)acrylate, and methoxypolypropylene glycol (meth)acrylate; (meth)acrylate monomers such as tetrahydrofurfuryl (meth)acrylate, fluoro (meth)acrylate, polysilicone (meth)acrylate, or 2-methoxyethyl acrylate. Further examples include isoprene, butadiene, isobutylene, and vinyl ether.

In addition, copolymerizable monomers other than the above-mentioned monomers include silane monomers containing silicon atoms, etc. Examples of silane monomers include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloxydecyltrimethoxysilane, 10-acryloxydecyltrimethoxysilane, 10-methacryloxydecyltriethoxysilane, 10-acryloxydecyltriethoxysilane, etc.

As the copolymer monomer, tripropylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, bisphenol A diglycidyl ether di(meth)acrylate, neopentyl glycol di(meth)acrylate, trihydroxymethylenepropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate may also be used. , esters of (meth)acrylic acid and polyols such as caprolactone-modified dipentatriol hexa(meth)acrylate, etc., having two or more (meth)acryloyl groups, vinyl groups or other unsaturated double bonds, or polyester (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, etc., having two or more (meth)acryloyl groups, vinyl groups or other unsaturated double bonds added to the skeleton of polyester, epoxy, urethane, etc. as the same functional groups as the monomer components.

The ratio of the other copolymerized monomers in the (meth)acrylic polymer (A) is preferably about 0 to 10%, preferably about 0 to 7%, and more preferably about 0 to 5%, based on the weight ratio of the total monomers (100% by weight) of the (meth)acrylic polymer (A).

The (meth)acrylic polymer (A) of the present invention generally has a weight average molecular weight of 1 million to 2.5 million. Considering durability, especially heat resistance, the weight average molecular weight is preferably 1.2 million to 2 million. From the perspective of heat resistance, it is preferable that the weight average molecular weight is above 1 million. Moreover, if the weight average molecular weight is greater than 2.5 million, the adhesive tends to harden and peeling occurs easily. In addition, the weight average molecular weight (Mw)/number average molecular weight (Mn) showing the molecular weight distribution is preferably greater than 1.8 and less than 10, preferably 1.8 to 7, and more preferably 1.8 to 5. If the molecular weight distribution (Mw/Mn) is greater than 10, it is not preferable from the perspective of durability. The weight average molecular weight and molecular weight distribution (Mw/Mn) were measured by GPC (gel permeation chromatography) and obtained from values calculated in terms of polystyrene.

The (meth)acrylic polymer (A) can be produced by appropriately selecting a known production method such as solution polymerization, block polymerization, emulsion polymerization, various radical polymerizations, etc. The obtained (meth)acrylic polymer (A) can be any of a random copolymer, a block copolymer, a graft copolymer, etc.

In solution polymerization, the polymerization solvent may be ethyl acetate, toluene, etc. As a specific example of solution polymerization, the reaction may be carried out under a flow of an inert gas such as nitrogen, with the addition of a polymerization initiator, and generally at about 50-70° C. for about 5-30 hours.

The polymerization initiator, chain transfer agent, emulsifier, etc. used in the free radical polymerization are not particularly limited and can be appropriately selected and used. In addition, the weight average molecular weight of the (meth)acrylic polymer (A) can be controlled by the amount of the polymerization initiator and chain transfer agent used and the reaction conditions, and the amount used can be appropriately adjusted according to the type of the initiator and chain transfer agent.

The adhesive composition of the present invention may contain an ionic compound (B). Alkali metal salts and/or organic cation-anion salts may be used as the ionic compound (B). Alkali metal salts may be organic salts and inorganic salts of alkali metals. In addition, the so-called "organic cation-anion salt" of the present invention means that it is an organic salt whose cation part is composed of an organic substance, and the anion part may be an organic substance or an inorganic substance. "Organic cation-anion salt" is also called an ionic liquid or an ionic solid. By making the adhesive layer contain the ionic compound (B), the surface resistance of the adhesive layer can be reduced and the generation of static electricity can be suppressed, thereby preventing static electricity from disturbing the orientation of the liquid crystal layer and causing light leakage (uneven charging).

>Alkali metal salts> The alkali metal ions constituting the cation portion of the alkali metal salts include ions of lithium, sodium, and potassium. Among these alkali metal ions, lithium ions are preferred.

The anion part of alkaline metal salts can be composed of organic or inorganic substances. As the anion part constituting the organic salt, for example, _CH3COO- ^, _{CF3COO- ,} ^{CH3SO3- ,} _CF3SO3- ^, ( _CF3SO2 ^{) 3C-} _{, C4F9SO3- , C3F7COO- , (} ^CF3SO2 )( _CF3CO ) _N- ^, _-O3S ( _CF2 ) _3SO3- ^, _PF6- ^, _CO32- or _those represented by the following general formulas (A _{) to (D) can be used: (A): (CnF2n+} ^{1SO2 )} _{2N- ( where n is an} integer of 0 to 10), (B): _{CF2 ( CmF2mSO2} ) ^2N- ( _where m _{is an integer of} 1 to 10), (C) ^{: -O3S (} _{CF2 ) 1SO3-} (However, l is an integer from 1 to 10), (D): (C _p F _{2p ＋1} SO ₂ )N ^- (C _q F _{2q ＋1} SO ₂ ) (However, p and q are integers from 1 to 10). In particular, an anion part containing fluorine atoms is suitable for use because an ionic compound with good ionic dissociation can be obtained. An anion part constituting an inorganic salt can use Cl ^- , Br ^- , I ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , BF ₄ ^- , PF ₆ ^- , ClO ₄ ^- , NO ₃ ^- , AsF ₆ ^- , SbF ₆ ^- , NbF ₆ ^- , TaF ₆ ^- , (CN) ₂ N ^- and the like. The anion part is preferably (perfluoroalkylsulfonyl)imide represented by the above general formula (A) such as (CF ₃ SO ₂ ) ₂ N ^- and (C ₂ F ₅ SO ₂ ) ₂ N ^- , and particularly preferably (trifluoromethanesulfonyl)imide represented by (CF ₃ SO ₂ ) ₂ N ^- .

Specific examples of the organic salt of an alkali metal include sodium acetate, sodium alginate, sodium lignosulfonate, sodium toluenesulfonate, LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, Li(CF ₃ SO ₂ ) ₂ N, Li(C ₂ F ₅ SO ₂ ) ₂ N, Li(C ₄ F ₉ SO ₂ ) ₂ N, Li(CF ₃ SO ₂ ) ₃ C, K0 ₃ S(CF ₂ ) ₃ SO ₃ K, and LiO ₃ S(CF ₂ ) ₃ SO ₃ K. Among them, LiCF ₃ SO ₃ , Li(CF ₃ SO ₂ ) ₂ N, Li(C ₂ F ₅ SO ₂ ) ₂ N, Li(C ₄ F ₉ SO ₂ ) ₂ N, and Li(CF ₃ SO ₂ ) ₃ C are preferred. Li(CF _{Fluorine -} containing lithium _imide salts such as bis(fluorosulfonyl ₎ lithium imide salts are preferred, _and (perfluoroalkylsulfonyl) lithium imide salts are particularly preferred. Other _examples include 4,4,5,5-tetrafluoro _{- 1,3,2 -} ditetrahydrothiazole- _{1,1,3,3 -} tetrahydrolithium salt.

Inorganic salts of alkaline metals include lithium perchlorate and lithium iodide.

>Organic cation-anion salt> The organic cation-anion salt used in the present invention is composed of a cationic component and an anionic component, and the cationic component is composed of an organic substance. Specific examples of the cationic component include pyridine cations, piperidine cations, pyrrolidine cations, cations having a dihydropyrrole skeleton, cations having a pyrrole skeleton, imidazole cations, tetrahydropyrimidine cations, dihydropyrimidine cations, pyrazole cations, pyrazoline cations, tetraalkylammonium cations, trialkylthionium cations, and tetraalkylphosphonium cations.

Examples ^of the anionic component that can be used include ^Cl- , ^Br- , ^I- , _AlCl4- , _Al2Cl7- ^{, BF4-} , _PF6- , _{ClO4- , NO3-, CH3COO-, CF3COO-, CH3SO3-, CF3SO3-} ^, _{( CF3SO2 )} ^3C- _, ^AsF6- _, ^SbF6- _{, NbF6- ,} ^TaF6- _{, (} ^{CN )} _{2N- ,} ^{C4F9SO3- , C3F7COO-} _, ^{( (} _CF3SO2 ^{) (} _{CF3CO ) N- ,} ^{-O3S (} _{CF2 ) 3SO3- ,} and ^those represented by the following general formulas ( _{A )} to ( _D ): (A ^{) :} _{( CnF2n + 1SO2 ) 2N-} (Note: n is an integer from 0 to 10), (B): CF ₂ (C _m F _2m SO ₂ ) ₂ N ^- (Note: m is an integer from 1 to 10), (C): ^- O ₃ S(CF ₂ ) _l SO ₃ ^- (Note: l is an integer from 1 to 10), (D): (C _p F _2p+1 SO ₂ )N ^- (C _q F _2q+1 SO ₂ ) (Note: p and q are integers from 1 to 10). Among them, anionic components containing fluorine atoms are particularly suitable for use because they can obtain ionic compounds with good ionic dissociation properties.

The organic cation-anion salt can be appropriately selected from compounds composed of the above-mentioned cationic components and anionic components. Preferred examples of organic cation-anion salts include methyl trioctyl ammonium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propyl pyrrolidinium bis(trifluoromethanesulfonyl)imide, and ethylmethylimidazolium bis(fluorosulfonyl)imide. Among them, 1-methyl-1-propyl pyrrolidinium bis(trifluoromethanesulfonyl)imide and ethylmethylimidazolium bis(fluorosulfonyl)imide are more preferred.

In addition, the ionic compound (B) includes, in addition to the aforementioned alkaline metal salts and organic cation-anion salts, inorganic salts such as ammonium chloride, aluminum chloride, cupric chloride, ferrous chloride, ferric chloride, and ammonium sulfate.

In order to obtain the desired resistance value, the aforementioned ionic compound (B) can be used alone or in combination. In particular, when the purpose is to control the surface resistance value of the adhesive layer within the range of 1×10 ¹⁰ ~1×10 ¹² Ω/□, the aforementioned ionic compound (B) is preferably an alkali metal salt from the viewpoint of improving the antistatic performance. By using an alkali metal salt, an adhesive with high antistatic performance can be obtained even with a small amount of mixing. On the other hand, when the purpose is to control the surface resistance of the adhesive layer within the range of 1×10 ⁸ ~1×10 ¹⁰ Ω/□, the ionic compound (B) is preferably an organic cationic-anionic salt from the viewpoint of improving the antistatic performance. By using an organic cationic-anionic salt, an adhesive with high antistatic performance can be obtained even with a relatively small mixing amount.

The ratio of the ionic compound (B) in the adhesive composition of the present invention should be appropriately adjusted to satisfy the antistatic properties of the adhesive layer and the sensitivity of the touch panel. For example, in order to make the surface resistance value of the adhesive layer in the range of 1.0×10 ⁸ ~1.0×10 ¹² Ω/□, it is advisable to adjust the ratio of the ionic compound (B) according to the type of liquid crystal panel with built-in touch sensing function while considering the weight ratio of the amide group-containing monomer (a2) introduced into the (meth) acrylic polymer (A), the type of transparent protective film of the polarizing film, etc. For example, in the built-in liquid crystal panel with built-in touch sensing function shown in FIG. 2, the initial surface resistance value of the adhesive layer is preferably controlled in the range of 1×10 ⁸ ~1×10 ¹⁰ Ω/□. In addition, in the semi-embedded type LCD panel with embedded touch sensing function as shown in FIG. 3 or the top-embedded type LCD panel as shown in FIG. 4 , the initial surface resistance value of the adhesive layer is preferably controlled within the range of 1×10 ¹⁰ ~1×10 ¹² Ω/□.

If the amount of the aforementioned ionic compound (B) increases, the ionic compound (B) may precipitate, and it is easy to peel due to wetting. The ratio of the aforementioned ionic compound (B), for example, relative to 100 parts by weight of the (meth)acrylic polymer (A), is generally preferably 40 parts by weight or less, and more preferably 30 parts by weight or less, and preferably 20 parts by weight or less, and most preferably 10 parts by weight or less. On the other hand, in order to improve the antistatic performance, it is advisable to use 0.01 parts by weight or more of the aforementioned ionic compound (B). Based on this viewpoint, the aforementioned ionic compound (B) is preferably 0.1 parts by weight or more, and more preferably 0.5 parts by weight or more. On the other hand, if the amount of the aforementioned ionic compound (B) increases, there is a risk that the surface resistance value becomes too low and the baseline shift occurs (misoperation during touch due to the low surface resistance value), which reduces the sensitivity of the touch panel.

The adhesive composition of the present invention may contain a crosslinking agent (C). As the crosslinking agent (C), an organic crosslinking agent or a multifunctional metal chelate may be used. Examples of organic crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. Multifunctional metal chelates are covalently bonded or coordinately bonded polyvalent metals and organic compounds. Examples of polyvalent metal atoms include Al, Cr, Zr, Co, Cu, Fe, Ni, V, Zn, In, Ca, Mg, Mn, Y, Ce, Sr, Ba, Mo, La, Sn, and Ti. Examples of atoms that can form covalent bonds or coordinate bonds in organic compounds include oxygen atoms, and examples of organic compounds include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

The crosslinking agent (C) is preferably an isocyanate crosslinking agent and/or a peroxide crosslinking agent.

The isocyanate crosslinking agent (C) may be a compound having at least two isocyanate groups, for example, aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, etc., which are known for urethanization reactions, are generally used.

Any peroxide that can generate free radical active species upon heating or light irradiation to crosslink the base polymer of the adhesive composition can be used appropriately. However, considering workability and stability, peroxides with a 1-minute half-life temperature of 80°C to 160°C are preferred, and peroxides with a temperature of 90°C to 140°C are more preferred.

Peroxides that can be used include di(2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6°C), di(4-t-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1°C), di-dibutyl peroxydicarbonate (1 minute half-life temperature: 92.4°C), tert-butyl peroxyneodecanoate (1 minute half-life temperature: 103.5°C), tert-hexyl peroxytrimethylacetate (1 minute half-life temperature: 109.1°C), tert-butyl peroxytrimethylacetate (1 minute half-life temperature: 110.3°C), dilauryl peroxide (1 minute half-life temperature: 112.1°C), and 1,1-di-butyl peroxide (1 minute half-life temperature: 113.3°C). Half-life temperature of 1 minute: 116.4℃), di-n-octyl peroxide (half-life temperature of 1 minute: 117.4℃), 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (half-life temperature of 1 minute: 124.3℃), di(4-methylbenzoyl) peroxide (half-life temperature of 1 minute: 128.2℃), dibenzoyl peroxide (half-life temperature of 1 minute: 130.0℃), tertiary butyl perisobutyrate (half-life temperature of 1 minute: 136.1℃), 1,1-di(tertiary hexylperoxy)cyclohexane (half-life temperature of 1 minute: 149.2℃), etc. Among them, di(4-tert-butylcyclohexyl)peroxydicarbonate (1 minute half-life temperature: 92.1°C), dilauryl peroxide (1 minute half-life temperature: 116.4°C), diphenylformyl peroxide (1 minute half-life temperature: 130.0°C) and the like are suitable for use from the viewpoint of good crosslinking reaction efficiency.

The amount of the crosslinking agent (C) used is preferably 3 parts by weight or less, more preferably 0.01 to 3 parts by weight, more preferably 0.02 to 2 parts by weight, and even more preferably 0.03 to 1 part by weight, relative to 100 parts by weight of the (meth)acrylic polymer (A). In addition, when the crosslinking agent (C) is less than 0.01 parts by weight, the adhesive layer may not be sufficiently crosslinked and may not satisfy the durability or adhesive properties; on the other hand, when it is more than 3 parts by weight, the adhesive layer may become too hard and the durability may be reduced.

The adhesive composition of the present invention may contain a silane coupling agent (D). The durability can be improved by using the silane coupling agent (D). Specific examples of the silane coupling agent include epoxy-containing silane coupling agents such as 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, and 2-(3-4-epoxycyclohexyl)ethyltrimethoxysilane; 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane; Silane coupling agents containing amino groups such as silane, 3-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine, and N-phenyl-γ-aminopropyltrimethoxysilane; silane coupling agents containing (meth)acryl groups such as 3-acryloxypropyltrimethoxysilane and 3-methacryloxypropyltriethoxysilane; silane coupling agents containing isocyanate groups such as 3-isocyanatepropyltriethoxysilane, etc. The silane coupling agents exemplified above are preferably silane coupling agents containing epoxy groups.

In addition, silane coupling agents (D) can also be used for those with multiple alkoxysilyl groups in the molecule. Specifically, they can be listed as X-41-1053, X-41-1059A, X-41-1056, X-41-1805, X-41-1818, X-41-1810, X-40-2651, etc. manufactured by Shin-Etsu Chemical Co., Ltd. Such silane coupling agents with multiple alkoxysilyl groups in the molecule are less volatile and have multiple alkoxysilyl groups, so they can effectively improve durability and are more ideal. In particular, when the adherend of the optical film with the adhesive layer is a transparent conductive layer (such as ITO, etc.) that is less likely to react with alkoxysilyl groups than glass, the durability is still good. Furthermore, the silane coupling agent having multiple alkoxysilyl groups in the molecule is preferably one having an epoxy group in the molecule, and more preferably one having multiple epoxy groups in the molecule. The silane coupling agent having multiple alkoxysilyl groups and an epoxy group in the molecule tends to have good durability when the adherend is a transparent conductive layer (such as ITO, etc.). Specific examples of the silane coupling agent having multiple alkoxysilyl groups and an epoxy group in the molecule include X-41-1053, X-41-1059A, and X-41-1056 manufactured by Shin-Etsu Chemical Co., Ltd., and X-41-1056 manufactured by Shin-Etsu Chemical Co., Ltd., which has a high epoxy group content, is particularly preferred.

The silane coupling agent (D) may be used alone or in combination of two or more thereof, but the total content is preferably 5 parts by weight or less, preferably 0.001 to 5 parts by weight, more preferably 0.01 to 1 part by weight, more preferably 0.02 to 1 part by weight, and preferably 0.05 to 0.6 parts by weight, based on 100 parts by weight of the (meth)acrylic polymer (A). This is an amount that can improve durability.

The adhesive composition of the present invention may contain a polyether compound (E) having a reactive silicon group. The polyether compound (E) is preferred from the viewpoint of improving the workability. The polyether compound (E) may be one disclosed in Japanese Patent Application Publication No. 2010-275522.

The ratio of the polyether compound (E) in the adhesive composition of the present invention is preferably 10 parts by weight or less, and more preferably 0.001 to 10 parts by weight relative to 100 parts by weight of the (meth)acrylic polymer (A). If the polyether compound (E) is less than 0.001 parts by weight, the effect of improving the workability is insufficient. The polyether compound (E) is preferably more than 0.01 parts by weight, and more preferably more than 0.1 parts by weight. On the other hand, if the polyether compound (E) is more than 10 parts by weight, it is not suitable from the perspective of durability. The polyether compound (E) is preferably less than 5 parts by weight, and more preferably less than 2 parts by weight. The ratio of the polyether compound (E) can be set to an appropriate range using the upper limit or lower limit mentioned above.

Furthermore, the adhesive composition of the present invention may also contain other known additives, such as polyether compounds of polyalkylene glycols such as polypropylene glycol, colorants, pigment powders, dyes, surfactants, plasticizers, tackifiers, surface lubricants, levelers, softeners, antioxidants, anti-aging agents, light stabilizers, ultraviolet absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, foils, etc., depending on the intended use. In addition, a redox system with a reducing agent added may be used within a controllable range. The additives are preferably used in an amount of 5 parts by weight or less, more preferably 3 parts by weight or less, and more preferably 1 part by weight or less relative to 100 parts by weight of the (meth)acrylic polymer (A).

The adhesive layer can be formed by, for example, applying the adhesive composition to a peeled separation piece, drying and removing the polymerization solvent, etc. to form an adhesive layer, and then transferring it to an optical film (polarizing film); or applying the adhesive composition to an optical film (polarizing film), drying and removing the polymerization solvent, etc. to form an adhesive layer on the optical film. In addition, one or more solvents other than the polymerization solvent may be appropriately added when applying the adhesive.

The thickness of the adhesive layer is not particularly limited, and is, for example, about 1 to 100 μm, preferably 2 to 50 μm, more preferably 2 to 40 μm, and even more preferably 5 to 35 μm.

>Image display panel, image display device> The polarizing film with an adhesive layer of the present invention can be applied to various image display panels, and the image display panel can be applied to conventional image display devices. The other structures of the image display device are the same as those of conventional image display devices. Specific examples of image display devices to which the image display panel can be applied include liquid crystal display devices, electroluminescent (EL) displays, plasma displays (PD), field emission displays (FED), etc.

The polarizing film with an adhesive layer has a small variation ratio of surface resistance and is suitable for application in liquid crystal panels with built-in touch sensing functions.

In addition to the above-mentioned structure, optical films such as phase difference film, viewing angle compensation film, and brightness enhancement film may be appropriately arranged in the liquid crystal panel.

The liquid crystal layer is not particularly limited, and any type such as TN type, STN type, π type, VA type, IPS type, etc. can be used. The transparent substrate 9 (light source side) can be any transparent substrate, and its material is not particularly limited, for example, glass or transparent resin film substrate can be mentioned. The transparent resin film substrate can be the above-mentioned.

In addition, on the light source side facing the liquid crystal layer, a polarizing film with an adhesive layer conventionally used in the art can be used, and those described in this specification can also be appropriately used.

Specific examples of the above-mentioned liquid crystal panel with built-in touch sensing function are shown in FIG2 to FIG4. FIG2 to FIG4 illustrate the polarizing film as the adhesive layer of the present invention, and the polarizing film 1 of the adhesive layer shown in FIG1 is used on the viewing side of the liquid crystal unit. That is, the single-sided protective polarizing film 11 and the adhesive 21 of FIG1 are shown as the first polarizing film 11 and the first adhesive layer 21 in FIG2 to FIG4.

FIG2 shows a so-called built-in touch sensing function liquid crystal panel, which has the following structure from the viewing side: first polarizing film 11/first adhesive layer 21/first transparent substrate 41/touch sensor portion 5/liquid crystal layer 3/driving electrode and sensor portion 6/second transparent substrate 42/second adhesive layer 22/second polarizing film 12. In the built-in touch sensing function liquid crystal panel of FIG2, for example, the liquid crystal cell C has the touch sensor portion 5 and the driving electrode and sensor portion 6 in the first and second glass substrates 41 and 42 sandwiching the liquid crystal layer 3 (inside the liquid crystal cell).

3 is a variation of a so-called built-in (semi-built-in) liquid crystal panel with a built-in touch sensing function, which has the following structure from the viewing side: first polarizing film 11/first adhesive layer 21/touch sensor portion 5/first transparent substrate 41/liquid crystal layer 3/driving electrode and sensor portion 6/second transparent substrate 42/second adhesive layer 22/second polarizing film 12. In the built-in liquid crystal panel with embedded touch sensing function of Figure 3, for example, the liquid crystal unit C is on the outside of the first transparent substrate 41, the touch sensor portion 5 is in direct contact with the first adhesive layer 21, and the liquid crystal unit C has a driving electrode and sensor portion 6 on the side of the second transparent substrate 42 within the first and second glass substrates 41 and 42 that sandwich the liquid crystal layer 3 (inside the liquid crystal unit).

4 shows a so-called top-mounted liquid crystal panel with a built-in touch sensing function, which has the following structure from the viewing side: first polarizing film 11/first adhesive layer 21/touch sensor portion 5/driving electrode and sensor portion 6/first transparent substrate 41/liquid crystal layer 3/driving electrode 7/second transparent substrate 42/second adhesive layer 22/second polarizing film 12. In the top-mounted liquid crystal panel with embedded touch sensing function shown in FIG4 , for example, the liquid crystal unit C has a touch sensor portion 5 and a drive electrode and sensor portion 6 on the outside of the first transparent substrate 41, the touch sensor portion 5 is in direct contact with the first adhesive layer 21, and the liquid crystal unit C has a drive electrode 7 on the side of the second transparent substrate 42 within the first and second glass substrates 41 and 42 that sandwich the liquid crystal layer 3 (inside the liquid crystal unit).

In a liquid crystal panel with a built-in touch sensor function, when the touch sensor portion 5 of the liquid crystal unit C directly contacts the first adhesive layer 21, the antistatic function of the first adhesive layer 21 (containing an ionic compound) is easily reduced, especially in a humidified environment. Therefore, the liquid crystal panel with a built-in touch sensor function of the present invention is suitable for application to the built-in type (variant) liquid crystal panel with a built-in touch sensor function shown in FIG. 3 or the top type liquid crystal panel with a built-in touch sensor function shown in FIG. 4 in the above examples.

In addition, the first polarizing film 11 disposed on the visual side of the liquid crystal unit C and the second polarizing film 12 disposed on the opposite side of the aforementioned visual side can be used in layers with other optical films according to the suitability of each configuration position. The aforementioned other optical films can be, for example, reflective plates or anti-transmission plates, phase difference films (including 1/2 or 1/4 wavelength plates), viewing angle compensation films, brightness enhancement films, etc., which can be used to form optical layers of liquid crystal display devices, etc. These can be used in one layer or two or more layers. When using these other optical films, it is also appropriate to use the adhesive layer closest to the liquid crystal layer 3 as the aforementioned first adhesive layer 21.

The liquid crystal layer 3 of the liquid crystal unit C can be a liquid crystal layer containing liquid crystal molecules that are parallel-oriented in the absence of an electric field and can be applied to a liquid crystal panel with an embedded touch sensor function. For example, an IPS type liquid crystal layer is suitable. In addition, the liquid crystal layer 3 can be any type of liquid crystal layer such as TN type, STN type, π type, VA type, etc. The thickness of the aforementioned liquid crystal layer is, for example, about 1.5 μm to 4 μm.

In the liquid crystal cell C, the first transparent substrate 41 and the second transparent substrate 42 can sandwich the liquid crystal layer 3 to form a liquid crystal cell. A touch sensor portion 5, a drive electrode and sensor portion 6, a drive electrode 7, etc. are formed inside or outside the liquid crystal cell in accordance with the shape of a liquid crystal panel with a built-in touch sensing function. In addition, a color filter substrate can be provided on the liquid crystal cell (the first transparent substrate 41).

The material forming the transparent substrate may be glass or a polymer film. The polymer film may be polyethylene terephthalate, polycycloolefin, polycarbonate, etc. When the transparent substrate is formed of glass, its thickness may be, for example, about 0.3 mm to 1 mm. When the transparent substrate is formed of a polymer film, its thickness may be, for example, about 10 μm to 200 μm. The transparent substrate may have an easy-to-adhesive layer or a hard coating layer on its surface.

The touch sensor part 5 (capacitive sensor), the driving electrode and sensor part 6, and the driving electrode 7 are formed as a transparent conductive layer. The constituent material of the aforementioned transparent conductive layer is not particularly limited, and can include metals such as gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, titanium, iron, cobalt, tin, magnesium, tungsten, and alloys of these metals. In addition, the constituent material of the aforementioned transparent conductive layer can include metal oxides of indium, tin, zinc, gallium, antimony, zirconium, and cadmium, and specifically can include metal oxides composed of indium oxide, tin oxide, titanium oxide, cadmium oxide, and mixtures thereof. Other metal compounds composed of copper iodide, etc. can be used. The aforementioned metal oxide may further contain oxides of metal atoms shown in the above group as required. For example, indium oxide containing tin oxide (ITO), tin oxide containing antimony, etc. are preferably used, and ITO is particularly suitable. ITO preferably contains 80-99% by weight of indium oxide and 1-20% by weight of tin oxide.

There is no limitation on where the touch sensor layer 5 is formed in the liquid crystal unit C, and the touch sensor layer 5 can be formed in accordance with the shape of the liquid crystal panel with a built-in touch sensing function. For example, FIG. 2 to FIG. 4 illustrate a case where the touch sensor layer 5 is arranged between the first polarizing film 11 and the liquid crystal layer 3. The touch sensor layer 5 can be formed on the first transparent substrate 41 as a transparent electrode pattern. Regarding the driving electrode and sensor portion 6 and the driving electrode 7, a transparent electrode pattern can also be formed according to a general method in accordance with the shape of the liquid crystal panel with a built-in touch sensing function. The above-mentioned transparent electrode pattern is usually electrically connected to a winding (not shown) formed at the end of the transparent substrate, and the above-mentioned winding is connected to a controller IC (not shown). The transparent electrode pattern may be in any shape, such as stripe or diamond, depending on the application, in addition to the comb shape. The height of the transparent electrode pattern is, for example, 10 nm to 100 nm, and the width is 0.1 mm to 5 mm.

In addition, the LCD panel with built-in touch sensing function can be appropriately used as a component of a LCD device such as a backlight or a reflector used in a lighting system. Implementation Example

The present invention is specifically described below with reference to the examples, but the present invention is not limited to the examples. In addition, the parts and % in each example are all based on weight. In the following, the room temperature conditions not specifically specified are all 23°C and 65%RH.

>Determination of the weight average molecular weight of the (meth)acrylic polymer (A)> The weight average molecular weight (Mw) of the (meth)acrylic polymer (A) is measured by GPC (gel permeation chromatography). The Mw/Mn is also measured in the same manner. The same applies to the measurement of the weight average molecular weight of polymer (a), etc. (excluding the solvent). ・Analysis device: HLC-8120GPC manufactured by Tosoh Corporation ・Column: G7000H _XL +GMH _XL +GMH _XL manufactured by Tosoh Corporation ・Column size: 7.8 mmφ×30 cm each, 90 cm in total ・Column temperature: 40°C ・Flow rate: 0.8 mL/min ・Injection volume: 100 μL ・Eluent: Tetrahydrofuran ・Detector: Differential refractometer (RI) ・Standard sample: Polystyrene

>Production of single-sided protected polarizing film (1)> (Production of thin polarizing element A) A single side of an amorphous isophthalic acid copolymer polyethylene terephthalate (IPA copolymer PET) film substrate (thickness: 100 μm) with a water absorption of 0.75% and a Tg of 75°C was subjected to a corona treatment, and an aqueous solution containing polyvinyl alcohol (polymerization degree 4200, saponification degree 99.2 mol%) and acetyl acetyl modified PVA (polymerization degree 1200, acetyl acetyl modification degree 4.6%, saponification degree 99.0 mol% or more, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gohsefimer Z200") in a ratio of 9:1 was applied to the corona treated surface at 25°C and dried to form a PVA resin layer with a thickness of 11 μm, thereby producing a laminate. The obtained laminate is subjected to free-end uniaxial stretching 2.0 times in the longitudinal direction (long side direction) between rollers of different circumferential speeds in an oven at 120°C (air-assisted stretching treatment). Then, the laminate is immersed in an insoluble bath (a boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid with 100 parts by weight of water) at a liquid temperature of 30°C for 30 seconds (insoluble treatment). Then, while it is immersed in a dyeing bath at a liquid temperature of 30°C, the iodine concentration and immersion time are adjusted so that the polarizing plate has a predetermined transmittance. In this embodiment, it is immersed in an iodine aqueous solution obtained by mixing 0.2 parts by weight of iodine and 1.0 parts by weight of potassium iodide with 100 parts by weight of water for 60 seconds (dyeing treatment). Next, it was immersed in a crosslinking bath (boric acid aqueous solution obtained by mixing 3 parts by weight of potassium iodide and 3 parts by weight of boric acid with respect to 100 parts by weight of water) at a liquid temperature of 30°C for 30 seconds (crosslinking treatment). Thereafter, while the laminate was immersed in a boric acid aqueous solution (an aqueous solution obtained by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 70°C, it was uniaxially stretched in the longitudinal direction (long side direction) between rollers of different peripheral speeds so that the total stretching ratio reached 5.5 times (in-water stretching). Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with respect to 100 parts by weight of water) at a liquid temperature of 30°C (cleaning treatment). In the above manner, an optical thin film laminate including a polarizer with a thickness of 5 μm was obtained.

(Preparation of adhesive for transparent protective film) 45 parts by weight of acrylamide, 45 parts of 1,9-nonanediol diacrylate, 10 parts of an acrylic oligomer obtained by polymerization of (meth)acrylic acid monomers (ARUFON UP1190, manufactured by Toagosei Co., Ltd.), 3 parts of a photopolymerization initiator (IRGACURE 907, manufactured by BASF), and 1.5 parts of a polymerization initiator (KAYACURE DETX-S, manufactured by Nippon Kayaku Co., Ltd.) were mixed to prepare a UV-curable adhesive.

(Preparation of a 25μm thick TAC film with a hard coat) A UV-curable resin monomer or oligomer having urethane acrylate as the main component was dissolved in butyl acetate (DIC Co., Ltd., trade name: UNIDIC 17-806, solid content concentration: 80%), and 5 parts of a photopolymerization initiator (BASF Co., Ltd., trade name: IRGACURE 907) and 0.1 parts of a leveling agent (DIC Co., Ltd., trade name: GRANDIC PC4100) were added to 100 parts of the solid content in the solution. Furthermore, cyclopentanone and propylene glycol monomethyl ether were added to the above solution at a ratio of 45:55 to make the solid content concentration in the above solution 36%, thereby preparing a hard coat forming material. The prepared hard coating layer forming material was applied to TJ25UL (manufactured by Fujifilm, raw material: cellulose triacetate polymer, thickness: 25 μm) so that the thickness of the hard coating layer after curing was 7 μm to form a coating film. After that, the coating film was dried at 90°C for 1 minute and irradiated with ultraviolet light with a high-pressure mercury lamp at a cumulative light intensity of 300 mJ/ ^cm2 to cure the aforementioned coating film to form a hard coating layer, thereby producing a 25 μm TAC (cellulose triacetate) film with HC.

(Preparation of single-sided protected polarizing film (1)) The above-mentioned UV-curable adhesive a is applied to the surface of the polarizing element A of the above-mentioned optical film laminate so that the adhesive layer thickness after curing reaches 1μm, and the above-mentioned transparent protective film (25μm TAC film with HC: cellulose triacetate film side) is attached, and then irradiated with ultraviolet rays as active energy rays to cure the adhesive. The ultraviolet irradiation is performed using a gallium-filled metal halogen lamp, the irradiation device: Light HAMMER10 manufactured by Fusion UV Systems, Inc., the bulb: V bulb, peak illuminance: 1600mW/ ^cm2 , cumulative irradiation 1000/mJ/ ^cm2 (wavelength 380~440nm), and the ultraviolet irradiance is measured using the Sola-Check system manufactured by Solatell. Then, the amorphous PET substrate is peeled off to produce a single-sided protected polarizing film (1) using a thin polarizer. The optical properties of the obtained single-sided protected polarizing film are a single body transmittance of 42.8% and a polarization degree of 99.99%.

>Production of double-sided protected polarizing film (2)> The aforementioned UV-curable adhesive a is applied to the polarizing element side (the side of the polarizing element not provided with a transparent protective film) of the single-sided protected polarizing film (1) so that the thickness of the adhesive layer after curing becomes 1 μm, and TJ25UL (manufactured by Fuji Film, raw material: cellulose triacetate polymer, thickness: 25 μm) is attached, and then UV rays are irradiated as active energy rays to cure the adhesive, thereby producing a double-sided protected polarizing film (2).

> Transparent layer forming material > Forming material A: The solution of urethane prepolymer (a) is a 75% ethyl acetate solution of urethane prepolymer composed of toluene diisocyanate (TDI) and trihydroxymethylpropane (TMP) (produced by Tosoh Corporation, trade name "CORONATE L"). On the other hand, trihydroxymethylpropane is dissolved in cyclopentanone and the solid content concentration is adjusted to 10% to prepare a trihydroxymethylpropane solution. The above-mentioned trihydroxymethylpropane solution was added to 100 parts of the above-mentioned 75% ethyl acetate solution of the urethane prepolymer (produced by Tosoh Corporation, trade name "Coronate L") to make the solid content ratio of urethane prepolymer:trihydroxymethylpropane 90:10, and then 0.1 parts of dioctyltin dilaurate catalyst (produced by Tokyo Fine Chemical CO., LTD., trade name "EMBILIZER OL-1") was added, and methyl isobutyl ketone was used as a solvent to prepare a forming material (coating liquid) with a solid content concentration of 10%.

Forming material B: 0.1 part of dioctyltin dilaurate catalyst (manufactured by Tokyo Fine Chemical Co., Ltd., trade name "Embilizer OL-1") was added to 100 parts of 75% ethyl acetate solution of urethane prepolymer composed of toluene diisocyanate and trihydroxymethyl propane, and methyl isobutyl ketone was used as a solvent to prepare a urethane prepolymer coating liquid with a solid content of 10%.

Forming material C: 97.0 parts of methyl methacrylate, 3.0 parts of the monomer represented by general formula (1): (monomer of general formula (1e)), and 0.2 parts of a polymerization initiator (2,2'-azobis(isobutyronitrile)) were dissolved in 200 parts of toluene. Then, the polymerization reaction was carried out for 5 hours while heating to 70°C in a nitrogen environment to obtain a polymer (a) (solid content concentration: 33% by weight). The weight average molecular weight of the obtained polymer (a) was 85,000. 15 parts of the above-mentioned polymer (a) and 85 parts of an epoxy resin (Mitsubishi Chemical Co., trade name: jER (registered trademark) YX7200B35) were mixed to prepare an acrylic-epoxy resin forming material (coating liquid).

>Preparation of conductive layer forming material> 8.6 parts of a solution containing 10 to 50% by weight of a thiophene polymer (trade name: Denatron P-580W, manufactured by Nagase ChemteX Co.) and 1 part of a solution of an oxazoline-based acrylic polymer (trade name: Epocros WS-700, manufactured by Nippon Catalyst Co., Ltd.) and 90.4 parts of water were mixed to prepare a coating liquid for forming a conductive layer having a solid content concentration of 0.5 wt%. The coating liquid for forming a conductive layer thus obtained contained 0.04 wt% of a polythiophene-based polymer and 0.25 wt% of a Azoline acrylic polymer.

Example 1 (Preparation of acrylic polymer (A)) A 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 inlet tube, and a cooler. And relative to 100 parts of the above-mentioned monomer mixture (solid component), 0.1 parts of 2,2'-azobisisobutyronitrile as a polymerization initiator and 100 parts of ethyl acetate were fed together, and nitrogen was introduced while slowly stirring to replace nitrogen. The liquid temperature in the flask was maintained at about 55°C, and the polymerization reaction was carried out for 8 hours to prepare an acrylic polymer solution with a weight average molecular weight (Mw) of 1.6 million and Mw/Mn=3.7.

(Preparation of adhesive composition) With respect to 100 parts of the solid content of the acrylic polymer solution obtained above, 0.1 parts of an isocyanate crosslinking agent (Takenate D160N manufactured by Mitsui Chemicals, trihydroxymethylpropane hexamethylene diisocyanate), 0.3 parts of benzoyl peroxide (NYPER BMT manufactured by NOF Corporation) and 0.3 parts of an epoxy-containing silane coupling agent (X-41-1056 manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed to prepare a solution of an acrylic adhesive composition.

(Preparation of adhesive layer) Then, the solution of the acrylic adhesive composition was applied to one side of a polyethylene terephthalate film (separation film: MRF38 manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.) treated with a silicone release agent so that the thickness of the adhesive layer after drying was 20 μm, and dried at 155°C for 1 minute to form an adhesive layer on the surface of the separation film.

>Preparation of a single-sided protected polarizing film with a transparent layer (1)> The transparent layer forming material A is applied to the polarizing element surface (the surface of the polarizing element not provided with the transparent protective film) of the single-sided protected polarizing film (1) using a rod coater, and then heat treated at 60°C for 12 hours to form a urethane resin layer with a thickness of 3μm.

> Formation of Conductive Layer> The conductive layer-forming coating liquid was applied to the transparent layer of the single-sided protected polarizing film (1) with a transparent layer so that the thickness after drying was 0.06 μm, and dried at 80° C. for 2 minutes to form a conductive layer. The conductive layer obtained contained 8 wt % of a thiophene polymer, 50 wt % of a Azoline acrylic polymer.

>Preparation of a single-sided protected polarizing film (1) with an adhesive layer> Then, the adhesive layer formed on the separation film is transferred to the conductive layer formed on the single-sided protected polarizing film (1) with a transparent layer, thereby producing a single-sided protected polarizing film (1) with an adhesive layer.

Examples 2-9, Comparative Examples 1-3, Reference Examples In Example 1, as shown in Table 1, the type of polarizing film, the composition of the monomer mixture used to prepare the acrylic polymer (A), the type (EMI-FSI or Li-TFSI) or the mixing ratio of the ionic compound (B) used to prepare the adhesive composition, the thickness of the adhesive layer, the presence or absence of the conductive layer, the formation material, type or thickness of the transparent layer are changed to be as shown in Table 1. Otherwise, a single-sided protected (or double-sided protected) polarizing film with an adhesive layer is prepared in the same manner as in Example 1. In addition, the transparent layer of Example 9 is formed by applying the transparent layer forming material C on the surface of the polarizer of the single-sided protective polarizing film (the surface of the polarizer without the transparent protective film) with a rod coater, and then performing a heat treatment at 60°C for 2 minutes to form a transparent layer with a thickness of 0.5μm. The transparent layer is not formed in the comparative example and the reference example. The conductive layer is not formed in Comparative Example 1, Comparative Examples 1 and 3. The reference example is to form a conductive layer on the side without the hard coating layer of the double-sided protective polarizing film (2) in the same manner as in Example 1, and then transfer the adhesive layer to the surface with the conductive layer formed. The blending amount of the ionic compound (B) is a value relative to 100 parts of the solid content of the acrylic polymer solution.

The following evaluations were performed on the single-sided protected (or double-sided protected) polarizing films with adhesive layers obtained in the above-mentioned embodiments, comparative examples and references. The evaluation results are listed in Table 1.

>Surface resistance (Ω/□): Conductivity> The surface resistance of the conductive layer is measured on the surface of the conductive layer of the single-sided (or double-sided) polarizing film with the conductive layer before the adhesive layer is formed. The surface resistance of the adhesive layer is measured on the surface of the adhesive layer formed on the separation film. After the separation film is peeled off from the single-sided (or double-sided) polarizing film with the adhesive layer, the surface resistance of the adhesive layer surface is measured as the surface resistance of the single-sided (or double-sided) polarizing film with the adhesive layer. The measurement is performed using MCP-HT450 manufactured by Mitsubishi Chemical ANALYTECH.

>Evaluation of end fading> The single-sided protected (or double-sided protected) polarizing film with adhesive layer obtained in the embodiment and comparative example was cut into 50mm×50mm, and after peeling off the separation film, it was attached to 1.2~1.5mm thick alkaline glass (made by Matsunami Glass Co., Ltd., slide glass) through the adhesive layer to prepare a sample. After the sample was kept in a high temperature and high humidity environment of 60℃ and 90%RH for 500 hours, the end fading amount was measured under the following conditions using a differential interference microscope (made by Olympus, product name "MX-61L"). The end fading amount is the distance between the part closest to the center of the part where the color becomes lighter than the center on the diagonal of the four corners of the sample and the corner as the end fading amount (μm), and the average value of the four corners is the end fading amount of the sample. Device: Olympus, MX-61L Measurement conditions Lens magnification: 5 times ISO: 200 Shutter speed: 1/100 Reflected light: 0 scale White balance: Automatic Transmitted light controller: LG-PS2 Transmitted light: 5 scale Transmitted light polarization direction: Orthogonal polarization direction to the transmission axis of the polarizing film

>ESD test> After removing the separation film from the single-sided protective (or double-sided protective) polarizing film of the adhesive layer, it is bonded to the visual side of the built-in liquid crystal unit or the top-mounted liquid crystal unit as shown in Table 1 to make a liquid crystal panel with a built-in touch sensor function. That is, the polarizing film with the adhesive layer obtained in Examples 2 to 8 and Comparative Example 3 is bonded to the first transparent substrate of the built-in liquid crystal unit shown in Figure 2 to form the first adhesive layer and the first polarizing film. The polarizing film with the adhesive layer obtained in Example 1, Comparative Examples 1, 2 and the Reference Example is bonded to the sensor layer (touch sensor part) of the top-mounted liquid crystal unit shown in Figure 4 to form the first adhesive layer and the first polarizing film. The polarizing film surface of the aforementioned liquid crystal panel was irradiated with an ESD (electrostatic discharge) gun (10kV), and the time for the whitened part due to electricity to disappear was measured and judged according to the following criteria. This was used as the initial evaluation. (Evaluation criteria) A: Within 0.5 seconds. B: More than 0.5 seconds and within 1 second. C: More than 1 second and within 10 seconds. D: More than 10 seconds. The obtained liquid crystal panel with built-in touch sensing function was placed in a humidified environment of 60℃/95%RH for 250 hours and dried at 40℃ for 1 hour, and then the same evaluation as above was performed.

[Table 1]

In Table 1: BA represents butyl acrylate, NVP represents N-vinyl-2-pyrrolidone, HBA represents 4-hydroxybutyl acrylate, AA represents acrylic acid, EMI-FSI represents ethylmethylimidazolium bis(fluorosulfonyl imide), and Li-TFSI represents lithium bis(trifluoromethanesulfonyl)imide.

As shown in Table 1, the polarizing film with an adhesive layer of the present invention can suppress the fading of the end of the polarizing element in a humidified environment even when a conductive layer is provided on the aforementioned polarizing element side of the single-sided protective polarizing film, and can suppress the increase in the resistance value of the adhesive layer in a humidified environment even when the adhesive layer contains an ionic compound.

1: Polarizing film with adhesive layer 11: Single-sided protective polarizing film, first polarizing film a: Polarizer b: Transparent protective film c: Transparent layer d: Conductive layer 21: Adhesive layer 12: Second polarizing film 21,22: First and second adhesive layers 3: Liquid crystal layer 41,42: First and second transparent substrates 5: Touch sensor unit 6: Drive electrode and sensor unit 7: Drive electrode C: Liquid crystal unit

FIG. 1 is a cross-sectional view showing an example of a polarizing film with an adhesive layer of the present invention. FIG. 2 is a cross-sectional view showing an example of a liquid crystal panel with a touch sensing function using a polarizing film with an adhesive layer of the present invention. FIG. 3 is a cross-sectional view showing an example of a liquid crystal panel with a touch sensing function using a polarizing film with an adhesive layer of the present invention. FIG. 4 is a cross-sectional view showing an example of a liquid crystal panel with a touch sensing function using a polarizing film with an adhesive layer of the present invention.

1: Polarizing film with adhesive layer

11: Single-sided protective polarizing film

a: Polarizer

b: Transparent protective film

c: Transparent layer

d: Conductive layer

21: Adhesive layer

Claims (20)

A polarizing film with an adhesive layer has a polarizing film and an adhesive layer; the polarizing film with an adhesive layer is characterized in that: the polarizing film has a polarizing element, a transparent protective film only on one side of the polarizing element, and a conductive layer is provided on the other side of the polarizing element via a transparent layer, the transparent layer is directly formed on the polarizing element and has a thickness of 0.5-10 μm, and the adhesive layer is provided via the conductive layer; the transparent layer is a hardened material containing a forming material of a urethane prepolymer (a) and a compound (b), the urethane prepolymer (a) is a reactant of an isocyanate compound and a polyol, and the compound (b) has at least two functional groups having active hydrogen reactive with an isocyanate group. A polarizing film with an adhesive layer as claimed in claim 1, wherein the aforementioned isocyanate compound contains at least one selected from toluene diisocyanate and diphenylmethane diisocyanate. A polarizing film with an adhesive layer has a polarizing film and an adhesive layer. The polarizing film with an adhesive layer is characterized in that: the polarizing film has a polarizing element, a transparent protective film is provided on only one side of the polarizing element, and a conductive layer is provided on the other side of the polarizing element via a transparent layer. The transparent layer is directly formed on the polarizing element and has a thickness of 0.5-10 μm, and the adhesive layer is provided via the conductive layer. The transparent layer contains epoxy resin. A polarizing film with an adhesive layer has a polarizing film and an adhesive layer. The polarizing film with an adhesive layer is characterized in that: the polarizing film has a polarizer, a transparent protective film only on one side of the polarizer, and a conductive layer is provided on the other side of the polarizer via a transparent layer, the transparent layer is directly formed on the polarizer and has a thickness of less than 10 μm, and the adhesive layer is provided via the conductive layer; the transparent layer is the following resin composition, the resin composition includes: (a) a polymer obtained by polymerizing more than 50 parts by weight of an acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of a monomer represented by the following general formula (1):

(wherein, X represents a functional group containing at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclohexane, hydroxy, amino, aldehyde and carboxyl groups; ^R1 and ^R2 represent independently a hydrogen atom, an aliphatic hydrocarbon group which may have a substituent, an aryl group which may have a substituent or a heterocyclic group which may have a substituent; and ^R1 and ^R2 may be linked to each other to form a ring); and (b) an epoxy resin; and the content ratio of the aforementioned polymer (a) to the epoxy resin (b) is 95:5 to 60:40 or 40:60 to 1:99 by weight. A polarizing film with an adhesive layer as claimed in claim 4, wherein the functional group represented by X in the aforementioned general formula (1) is a functional group represented by the following general formula (2): General formula (2): Z-Y- (wherein, Z represents a functional group containing at least one reactive group selected from the group consisting of vinyl, (meth)acryl, styryl, (meth)acrylamide, vinyl ether, epoxy, cyclohexane, hydroxy, amino, aldehyde and carboxyl groups, and Y represents an organic group). A polarizing film with an adhesive layer as claimed in any one of claims 1 to 5, wherein the thickness of the conductive layer is less than 1 μm. A polarizing film with an adhesive layer as claimed in any one of claims 1 to 5, wherein the conductive layer contains a conductive polymer. A polarizing film with an adhesive layer as claimed in any one of claims 1 to 5, wherein the conductive layer contains at least one selected from polythiophene, polyaniline, and carbon nanotubes. A polarizing film with an adhesive layer as claimed in any one of claims 1 to 5, wherein the adhesive layer is formed by an adhesive composition containing a (meth) acrylic polymer (A). A polarizing film with an adhesive layer as claimed in any one of claims 1 to 5, wherein the adhesive layer is formed of an adhesive composition containing a (meth)acrylic polymer (A) and an ionic compound (B). A polarizing film with an adhesive layer as claimed in claim 9, wherein the aforementioned (meth)acrylic polymer (A) contains (meth)acrylic acid alkyl ester (a1) and amide-containing monomer (a2) as monomer units. As in claim 11, the polarizing film with an adhesive layer, wherein the aforementioned amide-containing monomer (a2) is an N-vinyl lactam-containing monomer. As in claim 11, the polarizing film with an adhesive layer, wherein the aforementioned amide-containing monomer (a2) as a monomer unit contains 0.1% by weight or more in the aforementioned (meth)acrylic polymer (A). The polarizing film with an adhesive layer as claimed in claim 10, wherein the ionic compound (B) is an alkali metal salt, and the surface resistance of the adhesive layer is 1×10 ¹⁰ ~1×10 ¹² Ω/□. The polarizing film with an adhesive layer as claimed in claim 10, wherein the ionic compound (B) is an organic cation-anion salt, and the surface resistance of the adhesive layer is 1×10 ⁸ ~1×10 ¹⁰ Ω/□. The polarizing film with adhesive layer as claimed in claim 10, wherein the ionic compound (B) contains 0.01 parts by weight or more relative to 100 parts by weight of the (meth)acrylic polymer (A). A polarizing film with an adhesive layer as claimed in any one of claims 1 to 5, wherein the transparent protective film is a cellulose resin film or a (meth) acrylic resin film. An image display panel characterized by: a polarizing film having an adhesive layer as described in any one of claims 1 to 17. As in claim 18, the image display panel has an adhesive layer of the polarizing film attached with the adhesive layer attached to the liquid crystal unit with a built-in touch sensing function having a liquid crystal layer and a touch sensor portion. An image display device, characterized in that it has an image display panel as claimed in claim 18 or 19.

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