TWI889149B - Polarizing film with adhesive layer, image display panel and image display device - Google Patents

Abstract

The present invention is a polarizing film with an adhesive layer, which has a polarizing film and an adhesive layer. The polarizing film has a polarizer and a protective film located on one or both sides of the polarizer. The polarizing film with the adhesive layer has an irregular portion other than a rectangular portion. The adhesive layer is formed by an adhesive composition containing a (meth) acrylic polymer (A) and an ionic compound (B) with a molecular weight of 210 or less as a cationic component. The polarizing film with an adhesive layer with an irregular portion of the present invention can suppress the generation of irregular cracks and suppress static unevenness even when applied to a built-in liquid crystal panel.

Description

Polarizing film with adhesive layer, image display panel and image display device

The present invention relates to a polarizing film having an adhesive layer with a non-rectangular shaped portion, and also relates to an image display panel and an image display device using the polarizing film having the 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 (conductive layer) outside the polarizing film, the generation of static electricity can be suppressed.

For example, Patent Document 1 proposes that in a liquid crystal display device with a touch sensing function, a polarizing film having an antistatic layer with a surface resistance of 1.0×10 ⁹ to 1.0×10 ¹¹ Ω/□ be disposed on the viewing side of the liquid crystal layer to reduce the occurrence of display defects or failures. In addition, it is also known that adding an ionic compound as an antistatic agent to the adhesive layer can suppress the generation of static electricity.

On the other hand, in recent years, there has been an increase in irregular built-in liquid crystal display devices in smart phones and car navigation systems, and polarizing films have also been used in irregular shapes to match the display devices. Patent document 2 discloses a method for processing polarizing films to produce polarizing films with irregular shapes other than rectangular shapes. Patent document 3 discloses a method for making a transparent protective film used in a polarizing film contain irregular inorganic particles to improve the irregular punching properties of the polarizing film and the crack durability of the irregularly punched polarizing film after a heat cycle test.

Previous technical documents Patent documents Patent document 1: Japanese Patent Publication No. 2013-105154 Patent document 2: Japanese Patent Publication No. 2017-151191 Patent document 3: Japanese Patent Publication No. 2017-097111

Summary of the invention Problems to be solved by the invention According to the polarizing film with an antistatic layer described in Patent Document 1, the generation of static electricity can be suppressed. However, even a polarizing film with an adhesive layer having an antistatic layer or an adhesive layer containing an ionic compound cannot fully suppress static unevenness. As for a polarizing film with an irregular adhesive layer, a polarizing film with an antistatic layer or an adhesive layer containing an ionic compound cannot fully suppress irregular cracks generated in irregular portions. It is known that when a polarizing film with an adhesive layer containing an ionic compound and having an irregularly shaped portion is applied to an internal liquid crystal panel, a large amount of ionic compounds needs to be added to the adhesive layer, which results in the deterioration of the irregular cracks generated in the irregularly shaped portion.

The purpose of the present invention is to provide a polarizing film with an adhesive layer having an anti-static function, which is a polarizing film with an adhesive layer having an irregularly shaped portion, and can inhibit the generation of irregularly shaped cracks and static unevenness even when applied to a built-in liquid crystal panel.

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.

Means 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, and thus completed 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, wherein the polarizing film has a polarizer and a protective film located on one or both sides of the polarizer; The polarizing film with an adhesive layer is characterized in that: The polarizing film with an adhesive layer has an irregular portion other than a rectangular shape; The adhesive layer is formed by an adhesive composition containing a (meth) acrylic polymer (A) and an ionic compound (B) with a molecular weight of a cationic component of 210 or less.

In the polarizing film with the adhesive layer, the cationic component is preferably lithium ion.

The polarizing film with the adhesive layer preferably contains 0.1 to 13 parts by weight of the ionic compound (B) based on 100 parts by weight of the (meth)acrylic polymer (A).

In the polarizing film with an adhesive layer, the protective film is preferably selected from any one of a cellulose resin film and a (meth) acrylic resin film. In addition, the thickness of the polarizer in the polarizing film is preferably less than 10 μm.

The polarizing film with adhesive layer may be a single-sided protected polarizing film having a polarizer and a protective film only on one side of the polarizer. The single-sided protected polarizing film preferably has the adhesive layer on the other side of the polarizer.

The aforementioned single-sided protective polarizing film may have the aforementioned adhesive layer on the other side of the aforementioned polarizer via a transparent layer, and the transparent layer is directly formed on the aforementioned polarizer and has a thickness of less than 10 μm. As the aforementioned transparent layer, a hardened material containing a forming material of a urethane prepolymer may be used, and the urethane prepolymer is a reaction product of an isocyanate compound and a polyol.

In the polarizing film with an adhesive layer, the latent change value of the adhesive layer at 85° C. is preferably less than 120 μm.

The present invention also relates to an image display panel, which is characterized by having 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, wherein the polarizing film with the adhesive layer is attached.

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 with an adhesive layer of the present invention contains an ionic compound in the adhesive layer, and the anti-static performance can be improved through the adhesive layer. In addition, it is known that the smaller the molecular weight of the cationic component in the aforementioned ionic compound, the smaller the adverse effect on the irregular cracks, so the cationic component with a molecular weight of 210 or less is used. It is known that when the cationic component in the ionic compound uses a lithium salt, the effect of suppressing irregular cracks is good. And it is known that from the perspective of suppressing electrostatic unevenness, the smaller the molecular weight of the aforementioned cationic component, the better.

The polarizing film with adhesive layer of the present invention has an irregular portion other than a rectangular shape. For example, the polarizing film with adhesive layer of the present invention has an ionic compound with a small molecular weight of a cationic component mixed in the adhesive layer as an ionic compound. Therefore, even if the amount of the ionic compound is reduced, the antistatic function of the adhesive layer can still suppress static unevenness when the polarizing film with adhesive layer is applied to a built-in liquid crystal panel. In addition, the amount of the ionic compound can be reduced, so the generation of irregular cracks can be suppressed.

It is also known that the effect of suppressing irregular cracks is advantageous when a single-sided protected polarizing film having a protective film only on one side of the polarizer is used as the polarizing film. The single-sided protected polarizing film is also advantageous from the viewpoint of thinning and cost reduction.

On the other hand, it is also known that when a single-sided protected polarizing film is used as a polarizing film, in a humidified environment, the ionic compound contained in the adhesive layer will segregate to the polarizer, and there is a risk of reducing the antistatic function of the adhesive layer. As described above, when a single-sided protected polarizing film is used, by providing an adhesive layer on the polarizer via a transparent layer, the ionic compound in the adhesive layer will not directly affect the polarizer, thereby preventing the end of the polarizer from discoloring 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 polarizer even when a single-sided protective polarizing film is used, is thin and has good optical reliability, and has excellent long-term antistatic properties.

Form for implementing the invention 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 has a polarizing film 11 and an adhesive layer 21. FIG2 shows a case where the polarizing film 11 of FIG1 uses a single-sided protected polarizing film 11A having a protective film b only on one side of the aforementioned polarizer a, and the aforementioned single-sided protected polarizing film 11A has the aforementioned adhesive layer 21 on the other side of the side that does not have the protective film b to the aforementioned polarizer a. In addition, although not shown, the single-sided protected polarizing film A2 having a protective film b only on one side of the aforementioned polarizer a can also use a laminated product having polarizer a/protective film b/adhesive layer 21 laminated in sequence. FIG3 shows the case where the single-sided protective polarizing film 11A is used and a transparent layer d is provided on the other side of the polarizing element a. In FIG3 , the single-sided protective polarizing film 11A is provided with a transparent layer c and an adhesive layer 21 in sequence. From the perspective of suppressing the increase in the moisture content of the polarizing element in a high temperature and high humidity environment, the transparent layer c is preferably provided directly on the polarizing element a.

<Irregular Shape> The polarizing film with an adhesive layer of the present invention has an irregular shape other than a rectangle. FIG. 4 is a top view of an example of an irregular shape other than a rectangle. There is no particular limitation on the shape of the irregular shape, and any shape can be adopted according to the purpose, function and design of the polarizing film with an adhesive layer. Examples of irregular shapes other than a rectangle include a rectangle with a notch or a through hole.

The aforementioned notch portion can be provided at the outer edge of the polarizing film of the adhesive layer. When a plurality of the aforementioned notch portions are to be provided, they can be of the same shape or of different shapes. The aforementioned notch portions can be provided at least two on one side, or at least one on each of two sides. Furthermore, the aforementioned notch portion can be provided at one of the four outer edge corners in the rectangle, or at least two. In addition, the outer edge corners where the aforementioned notch portions are not provided can be square corners or rounded corners. The aforementioned notch portions can be composed of straight lines, curved lines, or a combination thereof. Figure 4 is an example of a polarizing film 1 with an adhesive layer of an irregular shape, in which notches 2 of different shapes are provided on the two short sides of the rectangle.

The length of the edge W1 of the notch portion can be appropriately adjusted according to the purpose of the polarizing film. For example, W1 is preferably adjusted within a range of about 2 to 100 mm. In addition, the maximum depth D of the notch portion 2 measured from the edge W1 is preferably adjusted within a range of about 2 to 100 mm.

FIG. 4 shows a case where the angle θ1 formed by the two straight lines constituting the shape of the notch 2 is 90°. The angle θ1 is greater than 90° and less than 180°, and preferably greater than 90° and less than 135°. When the angle θ1 falls outside the aforementioned range, in a severe environment of thermal shock, the stress generated by expansion and contraction will be concentrated on the portion 4 where the two straight lines intersect, making the portion 4 prone to cracks.

In addition, FIG. 4 shows a curve constituting the shape of the notch 2, and the curvature radius R1 of the curve is 0.2 mm or more, preferably 1 mm or more, more preferably 2 mm or more, more preferably 3 mm or more, and even more preferably 5 mm or more. When the curvature radius R1 is less than 0.2 mm, in a severe environment of thermal shock, the stress generated by expansion and contraction will be concentrated on the curved portion, making it easy for the curved portion to crack.

The through hole can be arranged inside the plane of the polarizing film with the adhesive layer. When a plurality of through holes are arranged inside the plane of the polarizing film with the adhesive layer, they can be of the same shape or different shapes. The through hole is composed of a straight line, a curved line or a combination thereof. The shape of the through hole can be, for example, a circle, an ellipse (one symmetry axis, two symmetry axes), a rounded rectangle, a quadrangle (square, rectangle) and a polygon with more than five corners.

The method of forming the above-mentioned irregular portion can include punching, end milling, laser processing, etc. The above-mentioned irregular portion is generally formed by the above-mentioned processing after laminating each layer.

<Polarizing film with adhesive layer> First, the components constituting the polarizing film with adhesive layer of the present invention are described. The polarizing film may be a polarizing element and a protective film on one or both sides of the polarizing element.

There is no particular limitation on the polarizer, and various polarizers can be used. As the polarizer, 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, the polarizer composed of polyvinyl alcohol films and dichroic substances such as iodine is 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, and less dimensional change, so it has 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 protective film, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier property, 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 protective film is generally bonded by an adhesive layer, and on the other side, the protective film can use a thermosetting resin or UV-curing resin such as (meth) acrylic, urethane, acrylic urethane, epoxy, or silicone.

The material of the protective film (transparent protective film) is preferably cellulose resin or (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 the issue of single-sided protection of polarizing film, that is, suppressing irregular cracks and cracks in polarizers, and is better from this point of view.

The protective film may also be a phase difference film, a brightness enhancement film, a diffusion film, etc. The phase difference film may be, for example, a film having a front phase difference of 40 nm or more and/or a thickness direction phase difference of 80 nm or more. The front phase difference is usually controlled within the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled within the range of 80 to 300 nm. When a phase difference film is used as a protective film, since the phase difference film can also function as a polarizer protective film, it can be made thinner.

The surface of the 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.

The protective film and polarizer are laminated via an intermediate layer such as an adhesive layer, an adhesive layer, or a primer layer. At this time, it is expected that the two can be laminated without an air gap through the intermediate layer. The protective film and polarizer are preferably laminated via an adhesive layer. As long as the adhesive used for bonding the polarizer and the protective film is optically transparent, various forms of adhesives such as water-based, solvent-based, hot melt adhesive-based, free radical curing, and cationic curing can be used without special restrictions, but water-based adhesives or free radical curing adhesives are more suitable.

<Adhesive layer> The adhesive layer is formed of an adhesive composition containing a (meth)acrylic polymer (A) and an ionic compound (B).

The (meth)acrylic polymer (A) contains an alkyl (meth)acrylate as a main component as a monomer unit. In addition, (meth)acrylate refers to 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 aforementioned alkyl (meth)acrylate 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 aforementioned alkyl (meth)acrylate can be considered as the remaining part of other copolymerized monomers. If the weight ratio of the aforementioned alkyl (meth)acrylate is set within the above range, it is better in ensuring adhesion.

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

Examples of the copolymerizable monomers include functional group-containing monomers such as carboxyl group-containing monomers, hydroxyl group-containing monomers, and amide group-containing monomers.

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 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 10% by weight or less, and preferably 0.01 to 8% by weight, more preferably 0.05 to 6% by weight, and more preferably 0.1 to 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 10% 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.

An amide group-containing monomer 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 amide group-containing monomers 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, and N-butyl(meth)acrylamide. Acrylamide monomers such as 1-(2-methyl)acrylamide, 1-(2-methyl)acrylamide, 1-(2-methyl)acrylamide, 1-(2-methyl)acrylamide, 1-(2-methyl)acrylamide; N-(2-methyl)acrylamide heterocyclic monomers such as N-(2-methyl)acrylamide, N-(2-methyl)acrylpiperidine, and N-(2-methyl)acrylpyrrolidine; N-vinyl lactam-containing monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam, etc. Amide-containing monomers are preferred because they can suppress the increase in surface resistance over time (especially in a humidified environment) and meet durability requirements, and are also preferred because they can suppress irregular cracks. Among the amide-containing monomers, N-vinyl lactam-based monomers are particularly preferred because they can suppress the increase in surface resistance over time (especially in a humidified environment), meet the durability requirements of the transparent conductive layer (touch sensor layer), and suppress irregular cracks.

A large weight ratio of the amide group-containing monomer tends to reduce the anchoring property of the optical film, so the weight ratio is preferably 10 weight % or less, and more preferably 5 weight % or less. From the perspective of suppressing the increase of the surface resistance value over time (especially in a humidified environment), the weight ratio of the amide group-containing monomer is preferably 0.1 weight % or more. The weight ratio is preferably 0.3 weight % or more, and more preferably 0.5 weight % or more. The amide group-containing monomer is more suitable in terms of the relationship with the ionic compound (B) contained in the adhesive layer of the present invention.

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 viscosity adjusted by doping the ionic compound (B) and maintain it within the range of the desired value even in a humidified environment, which is considered to be preferred. We believe that the presence of the amide group introduced into the side chain of the above-mentioned (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).

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. A polyfunctional monomer having two or more (meth)acryl groups, unsaturated double bonds such as vinyl groups, etc., such as esters of (meth)acrylic acid and polyols such as dipentatriol hexa(meth)acrylate modified with caprolactone, or polyester (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, etc., in which two or more unsaturated double bonds such as (meth)acryl groups, vinyl groups, etc. are added to the skeleton of polyester, epoxy, urethane, etc. as the same functional group as the monomer component.

The ratio of the aforementioned other copolymerized monomers in the (meth)acrylic polymer (A) is preferably about 0 to 10 wt %, preferably about 0 to 7 wt %, and more preferably about 0 to 5 wt %, based on the weight ratio of the total constituent monomers (100 wt %) of the aforementioned (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. On the other hand, 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 were obtained as 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.

<Ionic compound (B)> The ionic compound (B) contained in the adhesive composition forming the adhesive layer of the present invention is a cationic component having a molecular weight of 210 or less. From the perspective of suppressing the generation of irregular cracks, the molecular weight of the cationic component is preferably 150 or less, and more preferably 110 or less, and more preferably 50 or less, and more preferably 10 or less. The larger the molecular weight of the cationic component, the more it will hinder the (meth)acrylic polymers in the adhesive layer from entangled with each other, and there is a tendency to soften the physical properties of the adhesive layer. Therefore, the smaller the molecular weight, the less likely the physical properties of the adhesive layer will become soft, and the generation of irregular cracks can be suppressed. In addition, the smaller the molecular weight of the cationic component, the easier it is to reduce the surface resistance of the adhesive layer and suppress electrostatic unevenness, which is also better from this point of view.

In addition, the aforementioned ionic compound (B) may be appropriately used as an alkali metal salt and/or an organic cation-anion salt. Alkaline metal salts may be organic salts and inorganic salts of alkali metals. In addition, the so-called "organic cation-anion salt" in the present invention refers to an organic salt whose cation component is composed of organic matter, and the anion component may be either organic or inorganic. "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 salt> The alkali metal ions constituting the cationic component of the alkali metal salt include ions of lithium, sodium, and potassium. Among these alkali metal ions, lithium ions are preferred.

The anionic components of alkaline metal salts can be composed of organic or inorganic substances. Anion components constituting the organic salt may include _, 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 (1) to (4): (1): (CnF2n+1SO2 )} _{2N- ( where} ⁿ _{is an integer} ^{of 0} _{to 10} ), _{( 2} ) _{: CF2} ( _{CmF2mSO2 ) 2N-} ⁽ where _m is an integer of 1 to 10), ( ³ ) _: ^-O3S ( _{CF2 ) 1SO3-} (However, l is an integer from 1 to 10), (4): (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, anionic components containing fluorine atoms are suitable for use because they can obtain ionic compounds with good ionic dissociation properties. Anionic components constituting inorganic salts include 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 anionic component is preferably a (perfluoroalkylsulfonyl)imide represented by the general formula (1) such as (CF ₃ SO ₂ ) ₂ N ^- and (C ₂ F ₅ SO ₂ ) ₂ N ^- , and particularly preferably a (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 is preferred, 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, etc. are fluorine-containing lithium imide salts that are bis(fluorosulfonyl)imide lithium salts, and (perfluoroalkylsulfonyl)imide lithium 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.

As the anion component, for example _, ^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 ( 1} ⁾ _to ⁽ _{4 ) can} be used: ⁽ 1 ⁾ _: ⁽ _{CnF2n + 1SO2 )} ^{2N -} (except that n is an integer from 0 to 10), (2) CF ₂ (C _m F _2m SO ₂ ) ₂ N ^- (except that m is an integer from 1 to 10), (3) ^O ₃ S(CF ₂ ) _l SO ₃ ^- (except that l is an integer from 1 to 10), (4) (C _p F _2p+1 SO ₂ )N ^- (C _q F _2q+1 SO ₂ ) (except that 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.

When the aforementioned ionic compound (B) is an alkali metal salt, alkali metal ions such as lithium, sodium, and potassium are cationic components with a molecular weight of 210 or less, so an alkali metal salt with such alkali metal ions as a cationic component can be appropriately used. In particular, from the viewpoint of compatibility with the adhesive layer, an organic salt of an alkali metal in which the anionic component of the alkali metal salt is composed of an organic substance is preferably used. Moreover, the aforementioned alkali metal ion is preferably a lithium ion with the smallest molecular weight. The aforementioned ionic compound (B) is preferably a lithium salt, and an organic salt of lithium is particularly preferred. On the other hand, when the ionic compound (B) is an organic cationic-anionic salt, it is preferable to select from the cationic components exemplified above and have a molecular weight of 210 or less. In particular, from the viewpoint of compatibility with the adhesive layer, it is preferable to use an organic cationic-anionic salt whose anionic component is composed of an organic substance.

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 within 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 type of 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. 6, the initial surface resistance value of the adhesive layer should be controlled within the range of 1×10 ⁸ ~6×10 ¹⁰ Ω/□. In addition, in the semi-embedded type LCD panel with embedded touch sensing function as shown in FIG. 7 or the top-embedded type LCD panel as shown in FIG. 8 , 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 cause wetting and peeling. If the amount of the aforementioned ionic compound (B) increases, the surface resistance value may become too low and the baseline may shift (causing erroneous operation during touch due to the low surface resistance value), which may reduce the sensitivity of the touch panel. 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 20 parts by weight or less is more preferred, and 13 parts by weight or less is more preferred. If it is too little, there is a risk of poor antistatic properties, and if it is too much, there is a risk of reduced touch sensitivity, precipitation of ionic compounds, and deterioration of wetting and peeling of the adhesive. On the other hand, in order to improve the antistatic performance, it is preferred to use 0.1 parts by weight or more of the aforementioned ionic compound (B). Based on this viewpoint, the aforementioned ionic compound (B) is preferably 1 part by weight or more, and more preferably 5 parts by weight or more.

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: 116.4℃), di-n-octyl peroxide (1 minute half-life temperature: 117.4℃), 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (1 minute half-life temperature: 124.3℃), di(4-methylbenzoyl) peroxide (1 minute half-life temperature: 128.2℃), dibenzoyl peroxide (1 minute half-life temperature: 130.0℃), tert-butyl perisobutyrate (1 minute half-life temperature: 136.1℃), 1,1-di(tert-hexylperoxy)cyclohexane (1 minute half-life temperature: 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. Especially when the adherend of the optical film to which the adhesive is attached 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 also contain other known additives, such as polyether compounds with reactive silicon groups, 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 even more preferably 1 part by weight or less, based on 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.

The adhesive layer of the polarizing film with an adhesive layer applied to the present invention should preferably have a latent value of 120 μm or less, preferably 100 μm or less, more preferably 85 μm or less, and particularly preferably 60 μm or less at 85°C from the perspective of being applied to a shaped polarizing film. The lower limit of the latent value should preferably be 15 μm or more, preferably 30 μm or more. If the latent value is greater than 120 μm, there is a risk that cracks generated in the shaped polarizing film may deteriorate as described in the embodiment. If the latent value is less than 15 μm, the stress relaxation of the adhesive layer will be reduced, and therefore there is a risk that the adhesive layer may be easily peeled off during a durability test.

<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 that is transparent and can suppress the influence of the adhesive layer on the polarizer. The material can be, for example, a material forming a urethane prepolymer (a) that is a reaction product of an isocyanate compound and a polyol.

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

In addition, examples of the polyfunctional isocyanate compound include those having three or more isocyanate groups such as tris(6-isocyanatehexyl)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 causing 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 can generally be used in the form of a solution containing the aforementioned urethane prepolymer (a) and the aforementioned compound (b). The solution can be a solvent system, or an aqueous system such as an emulsion, a colloidal dispersion, or an aqueous solution.

There are no particular restrictions on the organic solvent as long as it does not have a functional group having active hydrogen that is 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 may be used or a combination of two or more organic solvents may be used. Furthermore, different organic solvents may be used for the aforementioned urethane prepolymer (a) and the aforementioned compound (b), respectively. At this time, the forming material may be prepared by mixing the solutions after preparing each solution. The organic solvent may 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 may 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 the urethane prepolymer.

In addition to the aforementioned urethane prepolymer, the material forming the transparent layer may include, for example, cyanoacrylate-based materials, epoxy-based materials, urethane acrylate-based materials, 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.

<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 Figures 6 to 8. Figures 6 to 8 illustrate the polarizing film as the adhesive layer of the present invention, and the polarizing film 1 of the adhesive layer shown in Figure 1 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 Figure 1 are shown as the first polarizing film 11 and the first adhesive layer 21 in Figures 6 to 8.

FIG6 is a so-called built-in type liquid crystal panel with built-in touch sensing function, 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 type liquid crystal panel with built-in touch sensing function of FIG6, 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).

7 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 LCD panel with embedded touch sensing function of Figure 7, 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).

8 is 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 FIG8 , 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. 7 or the top type liquid crystal panel with a built-in touch sensor function shown in FIG. 8 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 aforementioned transparent substrate may be glass or a polymer film. The aforementioned polymer film may be polyethylene terephthalate, polycycloolefin, polycarbonate, etc. When the aforementioned transparent substrate is formed of glass, its thickness is, for example, about 0.3 mm to 1 mm. When the aforementioned transparent substrate is formed of a polymer film, its thickness is, for example, about 10 μm to 200 μm. The aforementioned 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 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 transparent conductive layer can include metal oxides of indium, tin, zinc, gallium, antimony, zirconium, and cadmium, and specifically, metal oxides composed of indium oxide, tin oxide, titanium oxide, cadmium oxide, and mixtures thereof. Other metal compounds composed of copper iodide and the like can be used. The aforementioned metal oxides can 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. 6 to FIG. 8 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 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 for forming a LCD device, such as a backlight or a reflector in a lighting system. 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 acid polymer (A)> The weight average molecular weight (Mw) of the (meth)acrylic acid polymer (A) was measured by GPC (gel permeation chromatography). Mw/Mn was measured in the same manner. ・Analysis apparatus: HLC-8120GPC manufactured by Tosoh Corporation ・Column: G7000H _XL +GMH _XL +GMH _XL manufactured by Tosoh Corporation ・Column size: 7.8 mm φ × 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 Example 1> (Production of 40μm TAC film with HC and 25μm TAC film with HC) 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 so that the solid content concentration in the above solution became 36%, thereby producing a hard coating layer forming material. The prepared hard coating layer forming material was applied to TJ40UL (manufactured by Fujifilm, raw material: cellulose triacetate polymer, thickness: 40 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 (HC) and to produce a 40 μm TAC film with HC. Then, a hard coating layer (HC) with a thickness of 7 μm as described above was formed on TJ25UL (manufactured by Fuji Film, raw material: cellulose triacetate polymer, thickness: 25 μm) in the same manner to produce a 25 μm TAC film with HC.

<Production Example 2> (Production of 30μm acrylic film) In a 30L kettle reactor equipped with a stirring device, a temperature sensor, a cooling tube, and a nitrogen inlet tube, 8,000g of methyl methacrylate (MMA), 2,000g of methyl 2-(hydroxymethyl)acrylate (MHMA), 10,000g of 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), and 5g of n-dodecyl mercaptan were added, and the temperature was raised to 105°C and refluxed while nitrogen was passed through the reactor. Then, 5.0g of tertiary butyl peroxy isopropyl carbonate (Kayakarubon BIC-7, KAYAKU AKZO CO., LTD.) as a polymerization initiator, and a solution consisting of 10.0 g of tertiary butyl peroxy isopropyl carbonate and 230 g of MIBK was dripped over 4 hours, and solution polymerization was carried out at about 105-120°C under reflux, and aging was carried out for another 4 hours. 30 g of octadecyl phosphate/dioctadecyl phosphate mixture (Phoslex A-18, manufactured by Sakai Chemical Industry Co., Ltd.) was added to the obtained polymer solution, and a cyclocondensation reaction was carried out at about 90-120°C under reflux for 5 hours. Next, the obtained polymer solution was introduced into a vented twin-screw extruder (φ=29.75mm, L/D=30) at a processing speed of 2.0kg/h converted by the resin amount, and further cyclocondensation reaction and devolatization and extrusion were carried out in the extruder to obtain transparent pellets of a polymer containing a lactone ring. The vented twin-screw extruder had a barrel temperature of 260°C, a rotation speed of 100rpm, a reduced pressure of 13.3~400hPa (10~300mmHg), 1 rear vent hole, and 4 front vent holes. After dynamic TG measurement of the obtained lactone ring-containing polymer, a mass loss of 0.17 mass% was detected. The weight average molecular weight of the lactone ring-containing polymer is 133,000, the melt flow rate is 6.5 g/10 min, and the glass transition temperature is 131°C. The pellets obtained were kneaded and extruded with acrylonitrile-styrene (AS) resin (TOYO AS AS20, manufactured by TOYO STYRENE CO., LTD.) at a mass ratio of 90/10 using a uniaxial extruder (screw 30 mmφ) to obtain transparent pellets. The glass transition temperature of the obtained pellets is 127°C. The pellets were melt-extruded from a 400 mm wide coat hanger T-die using a 50 mmφ uniaxial extruder to produce a film with a thickness of 120 μm. The film was stretched 2.0 times longitudinally and 2.0 times transversely at 150°C using a biaxial stretching device to obtain a 30μm thick stretched film (30μm acrylic film). The optical properties of the stretched film were measured, and the total light transmittance was 93%, the in-plane phase difference Δnd was 0.8nm, and the thickness direction phase difference Rth was 1.5nm.

<Production of polarizing film (1)> A 45μm thick polyvinyl alcohol film was dyed in a 0.3% iodine solution at 30°C for 1 minute between rollers with different speed ratios and stretched to 3 times. Afterwards, the film was immersed in an aqueous solution containing 4% boric acid and 10% potassium iodide at 60°C for 0.5 minutes and stretched to a total stretching ratio of 6 times. After that, the film was immersed in an aqueous solution containing 1.5% potassium iodide at 30°C for 10 seconds to be washed, and then dried at 50°C for 4 minutes to obtain a polarizing film with a thickness of 18μm. The polarizing film (1) was prepared by laminating the saponified 40μm TAC film with HC obtained in Manufacturing Example 1 (cellulose triacetate film side) on one side of the polarizing element using a polyvinyl alcohol-based adhesive, and laminating the 30μm acrylic film obtained in Manufacturing Example 2 on the other side.

<Production of polarizing film (2)> (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 acetylacetyl-modified PVA (polymerization degree 1200, acetylacetyl-modified 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 side at 25°C and dried to form a PVA-based 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 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 (boric acid aqueous solution obtained by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with 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 to achieve a total stretching ratio of 5.5 times (stretching in water). After that, the laminate was immersed in a cleaning bath (an aqueous solution obtained by mixing 4 parts by weight of potassium iodide with 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.

<Production of polarizing film (2)> On the surface of the polarizing element A of the above-mentioned optical film laminate, the above-mentioned UV-curable adhesive is applied in a manner so that the thickness of the adhesive layer after curing becomes 1μm, and at the same time, the 25μm TAC film with HC obtained in the above-mentioned Manufacturing Example 1 (cellulose triacetate film side) is bonded thereto, and then irradiated with ultraviolet rays as active energy rays to cure the adhesive. The ultraviolet irradiation was performed using a gallium-filled metal halogen lamp, irradiation device: Light HAMMER10 manufactured by Fusion UV Systems, Inc., bulb: V bulb, peak irradiance: 1600mW/cm ² , cumulative irradiation 1000/mJ/cm ² (wavelength 380~440nm), and the ultraviolet irradiance was measured using the Sola-Check system manufactured by Solatell. Then, the amorphous PET substrate was peeled off to produce a polarizing film (2) using a thin polarizer. The optical properties of the obtained polarizing film were a single body transmittance of 42.8% and a polarization degree of 99.99%.

<Production of a polarizing film with a transparent layer (2)> After applying the following transparent layer forming material to the polarizing element surface of the polarizing film (2) (the surface of the polarizing element not provided with the 25μm TAC film with HC) using a bar coater, heat treatment was performed at 60°C for 12 hours to form a urethane resin layer with a thickness of 3μm, thereby producing a polarizing film with a transparent layer (2).

≪Materials for forming the transparent layer≫ The solution of the urethane prepolymer (a) is a 75% ethyl acetate solution of a urethane prepolymer composed of toluene diisocyanate (TDI) and trihydroxymethylpropane (TMP) (manufactured by Tosoh Corporation, trade name "CORONATE L"). On the other hand, a trihydroxymethylpropane solution is prepared by dissolving trihydroxymethylpropane in cyclopentanone to a solid content concentration of 10%. 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, trade name "Coronate L"), so that the solid content ratio of the urethane prepolymer: trihydroxymethylpropane was 90:10, and then 0.1 parts of dioctyl tin dilaurate catalyst (produced by Tokyo Fine Chemical CO., LTD., trade name "EMBILIZER OL-1") was added, and methyl isobutyl ketone was added as a solvent to prepare a forming material (coating liquid) with a solid content concentration of 10%.

Example 1 (Preparation of acrylic polymer (A)) A monomer mixture containing 78.9 parts of butyl acrylate, 16 parts of phenoxyethyl acrylate, 5 parts of acrylic acid, and 0.1 parts of 4-hydroxybutyl acrylate was added to a four-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 added together. After nitrogen substitution was performed while slowly stirring, the liquid temperature in the flask was maintained at about 55°C, and the polymerization reaction was carried out for 8 hours to prepare a solution of an acrylic polymer with a weight average molecular weight (Mw) of 2.2 million and Mw/Mn=4.0.

(Preparation of adhesive composition) 100 parts of the solid content of the acrylic polymer solution obtained above were mixed with 10 parts of lithium bis(trifluoromethanesulfonyl)imide, 0.6 parts of isocyanate crosslinking agent (Coronate L manufactured by Tosoh, trihydroxymethylpropane diisocyanate toluene), 0.1 parts of benzoyl peroxide (NYPER BMT manufactured by NOF Corporation) and 0.3 parts of epoxy-containing silane coupling agent (manufactured by Shin-Etsu Chemical Co., Ltd.: X-41-1056), to prepare an acrylic adhesive solution.

(Preparation of polarizing film with 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. Then, the adhesive layer formed on the separation film was transferred to the acrylic film side of the polarizing film (1) prepared above, thereby preparing a polarizing film with adhesive layer.

Examples 2 to 10, Comparative Examples 1 to 2 In Example 1, the monomer types and usage ratios used to prepare the acrylic polymer (A) were changed as shown in Table 1, and the manufacturing conditions were controlled to prepare the acrylic polymer (A) solution shown in Table 1.

As shown in Table 1, the type of polarizing film, the type of ionic compound (B) used to prepare the adhesive composition or the blending ratio thereof are changed to those shown in Table 1, and a polarizing film with an adhesive layer is prepared in the same manner as in Example 1. In addition, when the aforementioned polarizing film (2) is used as the polarizing film, the adhesive layer described in Table 1 is formed on the surface of the polarizer of the aforementioned polarizing film (2) (the surface of the polarizer without the 25μm TAC film with HC attached) in the same manner as described above, and when the aforementioned polarizing film (2) with a transparent layer is used as the polarizing film, the adhesive layer described in Table 1 is formed on the transparent layer of the aforementioned polarizing film (2) with a transparent layer in the same manner as described above.

The following evaluations were performed on the 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> After peeling off the separation film from the polarizing film with the adhesive layer, the surface resistance of the adhesive layer surface was measured as the surface resistance of the polarizing film with the adhesive layer. The measurement was performed using MCP-HT450 manufactured by Mitsubishi Chemical ANALYTECH.

<Determination of latent value> A polarizing film with an adhesive layer (adhesive layer thickness: 20μm) cut into a size of 10mm×30mm was attached to a SUS plate with a 10mm×10mm upper end through the adhesive layer and autoclaved for 15 minutes at 50℃ and 5 atmospheres. A precision heating plate with a heating surface set vertically was heated to 85℃, and the SUS plate with the polarizing film with the adhesive layer attached was set so that the surface without the adhesive layer was in contact with the heating surface of the heating plate. After heating the SUS plate at 85°C for 5 minutes, a load of 500g was applied to the lower end of the polarizing film with the adhesive layer and left for 1 hour. The offset amplitude of the polarizing film with the adhesive layer and the SUS plate before and after the load was applied was measured, and the offset amplitude was taken as the latent value (μm) at 85°C.

<Durability test> The polarizing film with adhesive layer was cut into a size of 300×220mm with the absorption axis of the polarizing film parallel to the long side. The polarizing film with adhesive layer was bonded to 350×250mm×0.7mm thick alkali-free glass (Corning Company, trade name "EG-XG") using a bonding machine. Then, it was treated in an autoclave at 50℃ and 0.5MPa for 15 minutes to make the adhesive layer adhere to the glass. After the sample treated as above was treated for 500 hours in a gas environment of 85℃ and 500 hours in a gas environment of 60℃/95%RH, the appearance of the sample was evaluated by naked eyes according to the following criteria. (Evaluation criteria) A: There is no change in appearance such as bubbling or peeling. B: Although there is a little peeling or bubbling at the ends, it is not a problem in practical use. C: There is peeling or bubbling at the ends, but it is not a problem in practical use unless it is used for special purposes. D: There is significant peeling at the ends, which is a problem in practical use.

<ESD test> After removing the separation film from the polarizing film with adhesive layer, it is attached to the visual side of the built-in liquid crystal unit to make a liquid crystal panel with built-in touch sensing function. That is, the polarizing film with adhesive layer obtained is attached to the first transparent substrate of the built-in liquid crystal unit shown in Figure 6 to form the first adhesive layer and the first polarizing film. ESD (electrostatic discharge) gun (10kV) is fired at the polarizing film surface of the aforementioned liquid crystal panel, and the time for the whitened part due to electricity to disappear is measured and judged according to the following standards. (Evaluation standard) A: Within 1 second. B: More than 1 second and within 10 seconds. C: More than 10 seconds.

<Evaluation of irregular cracks> The polarizing film with adhesive layer was processed into the shape shown in Figure 5 using a _CO2 laser processing machine Spirit (GCC, 30W) at a speed of 10, a laser output of 35, and 400ppi. The polarizing film with adhesive layer after irregular processing was bonded to 350mm×250mm×0.7mm thick alkali-free glass (Corning, trade name "EG-XG"), and then autoclaved at 50℃ and 0.5MPa for 15 minutes to make the adhesive layer adhere to the glass. The sample that has been treated as described above was put into a heat cycle test tank, and the presence of irregular cracks was confirmed by naked eyes at the time points of 100 cycles and 200 cycles. Five identical samples were placed under each condition, and the number of samples with cracks is recorded in Table 1. (Test conditions) Temperature conditions: -40℃ (hold for 30 minutes) ⇒ 85℃ (hold for 30 minutes) as one cycle, and the heating and cooling rate: 10℃/min

<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: the direction of orthogonal polarization to the transmission axis of the polarizing film

[Table 1]

In Table 1: BA represents butyl acrylate, PEA: phenoxyethyl acrylate, AA represents acrylic acid, NVP represents N-vinyl-2-pyrrolidone, HBA: 4-hydroxybutyl acrylate, Isocyanate represents isocyanate crosslinking agent (CORONATE L manufactured by Tosoh, trihydroxymethylpropane diisocyanate toluene), BPO represents benzoyl oxide (NYPER BMT manufactured by NOF Corporation), Li-TFSI represents lithium bis(trifluoromethanesulfonyl)imide, K-potassium bis(trifluoromethanesulfonyl)imide, TMPA-TFSI represents trimethylpropylammonium bis(trifluorosulfonylimide), EMP-TFSI represents ethylmethylpyrrolidinium bis(trifluorosulfonylimide), TBMA-TFSI stands for tributyl methyl ammonium bis(fluorosulfonyl imide), MTOA-TFSI stands for trioctyl methyl ammonium bis(trifluorosulfonyl imide).

1: Polarizing film with adhesive layer 2: Notch (irregular shape) 3: Liquid crystal layer 4: Intersection of two straight lines 5: Touch sensor 6: Drive electrode and sensor 7: Drive electrode 11: Single-sided protective polarizing film 11A: Single-sided protective polarizing film 12: Second polarizing film 21: (First) adhesive layer 22: Second adhesive layer 41: First transparent substrate 42: Second transparent substrate A2: Single-sided protective polarizing film C: Liquid crystal unit D: Maximum depth of notch from W1 R1: Radius of curvature of curve W1: Length of notch a: Polarizer b: Protective film c: transparent layer θ1: angle formed by two straight lines

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 polarizing film with an adhesive layer of the present invention. FIG. 3 is a cross-sectional view showing an example of a polarizing film with an adhesive layer of the present invention. FIG. 4 is a top view showing an example of an irregular portion other than a rectangular portion of the polarizing film with an adhesive layer of the present invention. FIG. 5 is a top view showing an example of a polarizing film with an adhesive layer having an irregular portion of an embodiment of the present invention. FIG. 6 is a cross-sectional view showing an example of a liquid crystal panel with a touch sensing function using the polarizing film with an adhesive layer of the present invention. FIG. 7 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. 8 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:Polarizing film

21: Adhesive layer

Claims (12)

A polarizing film with an adhesive layer comprises a polarizing film and an adhesive layer, wherein the polarizing film comprises a polarizing element and a protective film located on one side or both sides of the polarizing element; the polarizing film with an adhesive layer is characterized in that: the polarizing film with the adhesive layer has an irregularly shaped portion other than a rectangular shape; the adhesive layer is formed by an adhesive composition containing a (meth) acrylic polymer (A) and an ionic compound (B) having a molecular weight of 210 or less of a cationic component; and the latent change value of the adhesive layer at 85°C is greater than 15µm and less than 120μm. A polarizing film with an adhesive layer as claimed in claim 1, wherein the cationic component is lithium ion. The polarizing film with an adhesive layer according to claim 1 or 2 contains 0.1 to 13 parts by weight of the aforementioned ionic compound (B) relative to 100 parts by weight of the aforementioned (meth)acrylic polymer (A). A polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the protective film is selected from any one of a cellulose resin film and a (meth) acrylic resin film. A polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the thickness of the polarizing element is less than 10 μm. A polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the polarizing film is a single-sided protected polarizing film having a polarizing element and a protective film only on one side of the polarizing element. As for the polarizing film with adhesive layer of claim 6, in which the aforementioned single-sided protected polarizing film has the aforementioned adhesive layer on the other side of the aforementioned polarizer. A polarizing film with an adhesive layer as claimed in claim 7, wherein the other side of the aforementioned polarizer in the aforementioned single-sided protected polarizing film has the aforementioned adhesive layer via a transparent layer, and the transparent layer is directly formed on the aforementioned polarizer and has a thickness of less than 10 μm. The polarizing film with an adhesive layer as claimed in claim 8, wherein the transparent layer is a cured product of a forming material containing a urethane prepolymer, and the urethane prepolymer is a reaction product of an isocyanate compound and a polyol. An image display panel is characterized by having a polarizing film with an adhesive layer as described in any one of claims 1 to 9. As in claim 10, the image display panel includes a liquid crystal unit with a built-in touch sensing function having a liquid crystal layer and a touch sensor portion, and an adhesive layer of a polarizing film having the aforementioned adhesive layer attached thereto. An image display device is characterized by having an image display panel as claimed in claim 10 or 11.

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