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

Abstract

This invention relates to a polarizing film with an adhesive layer, comprising a polarizing film and an adhesive layer. The polarizing film has a polarizing element and a protective film located on one or both sides of the polarizing element. The polarizing film with the adhesive layer has irregularly shaped portions other than rectangular. The adhesive layer is formed from an adhesive composition containing a (meth)acrylic acid polymer (A) and an ionic compound (B) with a cationic component and a molecular weight of 210 or less. Even when applied to an integrated liquid crystal panel, the polarizing film with the irregularly shaped adhesive layer of this invention can suppress the generation of irregular cracks and suppress electrostatic unevenness.

Description

Technical Field

[0001] The present invention relates to a polarizing film with an adhesive layer having a non-rectangular portion, and also to an image display panel and an image display device using the polarizing film with an adhesive layer. Prior Art

[0002] Image display panels, such as those used in liquid crystal display devices, typically have polarizing films laminated on both sides of a liquid crystal cell through adhesive layers. The liquid crystal cell is formed by a liquid crystal layer disposed between a pair of transparent substrates. During the manufacture of image display panels, when the polarizing film with an adhesive layer is attached to the liquid crystal cell, a release film is peeled off from the adhesive layer of the polarizing film with an adhesive layer. This release film generates static electricity. This static electricity can affect the orientation of the liquid crystal layer within the liquid crystal display panel, leading to defects. Therefore, forming an antistatic layer (conductive layer) on the outer surface of the polarizing film can suppress the generation of static electricity.

[0003] For example, Patent Document 1 proposes placing a polarizing film with an antistatic layer having a surface resistance of 1.0×10⁻¹⁻Ω / □ on the viewing side of the liquid crystal layer in a touch-sensitive liquid crystal display device to reduce display defects or malfunctions. Furthermore, it is known that adding ionic compounds as antistatic agents to adhesive layers can suppress static electricity generation.

[0004] Meanwhile, in recent years, smartphones and car navigation systems have seen an increase in the use of irregularly shaped built-in liquid crystal displays, and polarizing films have also been used in irregular shapes to match these displays. Patent Document 2 discloses a method for processing polarizing film to produce irregular shapes other than rectangular. Patent Document 3 describes a method for improving the irregular punching properties of the polarizing film and the crack resistance of the irregularly shaped polarizing film after thermal cycling testing by incorporating irregularly shaped inorganic particles into the transparent protective film used for the polarizing film.

[0005] Prior Art Literature Patent Literature Patent Document 1: Japanese Patent Application Laid-Open No. 2013-105154 Patent Document 2: Japanese Patent Application Publication No. 2017-151191 Patent Document 3: Japanese Patent Application Publication No. 2017-097111 Summary of the Invention

[0006] Summary of the Invention Problems that the invention aims to solve According to the polarizing film with an antistatic layer described in Patent Document 1, static electricity generation can be suppressed. However, even polarizing films with adhesive layers that include an antistatic layer or an adhesive layer containing an ionic compound cannot fully suppress static unevenness. Furthermore, polarizing films with adhesive layers that include an antistatic layer or an adhesive layer containing an ionic compound cannot fully suppress irregular cracks that occur in irregularly shaped portions. It is known that when polarizing films with adhesive layers that include an ionic compound and irregularly shaped portions are used in built-in liquid crystal panels, a large amount of ionic compounds must be added to the adhesive layer, which worsens the irregular cracks that occur in the irregularly shaped portions.

[0007] The present invention aims to provide a polarizing film with an adhesive layer having antistatic properties, wherein the polarizing film has an adhesive layer with a special-shaped portion and can suppress the generation of special-shaped cracks and static unevenness even when used in built-in liquid crystal panels.

[0008] Furthermore, an object of the present invention is to provide an image display panel and an image display device using the polarizing film with the adhesive layer.

[0009] Means used to solve problems The present inventors have diligently studied and researched to solve the aforementioned problems, and have discovered the following polarizing film with an adhesive layer, thereby completing the present invention.

[0010] That is, the present invention relates to a polarizing film with an adhesive layer, which comprises a polarizing film and an adhesive layer, wherein the polarizing film comprises 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 the adhesive layer has a shaped portion other than a rectangle; The adhesive layer is formed of an adhesive composition containing a (meth)acrylic polymer (A) and an ionic compound (B) having a molecular weight of 210 or less as a cationic component.

[0011] In the polarizing film with an adhesive layer, the cationic component is preferably a lithium ion.

[0012] The polarizing film with an 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).

[0013] In the aforementioned polarizing film with an adhesive layer, the aforementioned protective film is preferably selected from any one of a cellulose resin film and a (meth)acrylic resin film. Furthermore, the thickness of the aforementioned polarizer in the aforementioned polarizing film is preferably 10 μm or less.

[0014] The polarizing film with an adhesive layer may be a single-sided protected polarizing film having a polarizer and a protective film on only one side of the polarizer. The single-sided protected polarizing film preferably has the adhesive layer on the other side of the polarizer.

[0015] The single-sided protective polarizing film may include the adhesive layer on the other side of the polarizer, with a transparent layer interposed therebetween. The transparent layer is formed directly on the polarizer and has a thickness of 10 μm or less. The transparent layer may be a cured product containing a urethane prepolymer, which is a reaction product of an isocyanate compound and a polyol.

[0016] In the polarizing film with an adhesive layer, the adhesive layer preferably has a creep value of 120 μm or less at 85°C.

[0017] The present invention further relates to an image display panel characterized by comprising the aforementioned polarizing film with an adhesive layer. The image display panel can be applied to a liquid crystal cell with an embedded touch sensor function having a liquid crystal layer and a touch sensor portion, wherein the adhesive layer of the polarizing film with an adhesive layer is bonded to the liquid crystal cell.

[0018] The present invention further relates to an image display device, characterized in that it has the above-mentioned image display panel.

[0019] Effects of the Invention The polarizing film with an adhesive layer of the present invention contains an ionic compound in the adhesive layer, which enhances antistatic properties through the adhesive layer. Furthermore, it is known that the smaller the molecular weight of the cationic component in the ionic compound, the less adverse effect it has on irregular cracks. Therefore, a cationic component with a molecular weight of 210 or less is used. It is known that using a lithium salt as the cationic component in the ionic compound is particularly effective in suppressing irregular cracks. Furthermore, from the perspective of suppressing static unevenness, it is known that the smaller the molecular weight of the cationic component, the better.

[0020] The polarizing film with an adhesive layer of the present invention has irregularly shaped portions other than rectangular. For example, the adhesive layer of the polarizing film with an adhesive layer of the present invention contains a low-molecular-weight ionic compound as a cationic component. 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 an adhesive layer is used in a built-in liquid crystal panel. Furthermore, by reducing the amount of the ionic compound, the occurrence of irregularly shaped cracks can be suppressed.

[0021] It is also known that the effect of suppressing irregular cracks is beneficial when a single-sided protective polarizing film having a protective film only on one side of the polarizer is used as the polarizing film. Single-sided protective polarizing film is also advantageous from the perspective of thinning and cost reduction.

[0022] On the other hand, it is known that when a single-sided protective polarizing film is used as a polarizing film, the ionic compounds contained in the adhesive layer may segregate into the polarizer under humid conditions, potentially reducing the antistatic properties of the adhesive layer. As described above, when using a single-sided protective polarizing film, by providing the adhesive layer on the polarizer via a transparent layer, the ionic compounds in the adhesive layer are prevented from directly affecting the polarizer, thereby preventing discoloration of the polarizer's edge in humid conditions.

[0023] 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 degradation of the optical reliability 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. Simple diagram description

[0024] FIG1 is a cross-sectional view showing an example of a polarizing film with an adhesive layer according to the present invention. FIG. 2 is a cross-sectional view showing an example of a polarizing film with an adhesive layer according to the present invention. FIG3 is a cross-sectional view showing an example of a polarizing film with an adhesive layer according to the present invention. FIG. 4 is a top view showing an example of a non-rectangular irregular portion of the polarizing film with an adhesive layer according to the present invention. FIG. 5 is a top view showing a polarizing film with an adhesive layer having a special-shaped portion according to an embodiment of the present invention. FIG6 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 the polarizing film with an adhesive layer of the present invention. FIG8 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. Implementation Method

[0025] Mode for carrying out the invention An example of a polarizing film with an adhesive layer according to the present invention is shown in FIG1 . As shown in FIG1 , the polarizing film with an adhesive layer 1 comprises a polarizing film 11 and an adhesive layer 21. FIG2 illustrates the polarizing film 11 of FIG1 using a single-sided protective polarizing film 11A having a protective film b on only one side of the polarizer a. The single-sided protective polarizing film 11A has the adhesive layer 21 on the side opposite the polarizer a that does not have the protective film b. Furthermore, although not shown, a single-sided protective polarizing film A2 having a protective film b on only one side of the polarizer a may also be used, comprising a laminate of polarizer a, protective film b, and adhesive layer 21 in this order. FIG3 illustrates the single-sided protective polarizing film 11A further comprising a transparent layer d on the other side of the polarizer a. In FIG3 , the single-sided protective polarizing film 11A is provided with a transparent layer c and an adhesive layer 21 in this order. From the perspective of suppressing the increase in the moisture content of the polarizer under high temperature and high humidity environments, the transparent layer c is preferably provided directly on the polarizer a.

[0026] <Alien Department> The polarizing film with an adhesive layer of the present invention may also have a non-rectangular shaped portion. Figure 4 is a top view of an example of a non-rectangular shaped portion. The shape of the non-rectangular shaped portion is not particularly limited and may be any shape depending on the application, function, and design of the polarizing film with an adhesive layer. Examples of non-rectangular shaped portions include a rectangular portion with a notch or through-hole.

[0027] The aforementioned notch can be provided on the outer edge of the polarizing film with an adhesive layer. If multiple notches are provided, they can be of the same shape or different shapes. Two or more notches can be provided on one side, or one or more on each of two sides. Furthermore, the notch can be provided at one of the four outer corners of the rectangle, or at least two. Furthermore, the outer corners without the aforementioned notch can be square or rounded. The notch can be formed by straight lines, curves, or a combination thereof. Figure 4 shows an example of a polarizing film 1 with an adhesive layer having a different shape, with notches 2 of different shapes provided on each of the two short sides of the rectangle.

[0028] The length of the edge W1 of the notch can be adjusted appropriately depending on the intended use of the polarizing film. For example, W1 is preferably adjusted within a range of approximately 2 to 100 mm. Furthermore, the maximum depth D of the notch 2, measured from the edge W1, is preferably adjusted within a range of approximately 2 to 100 mm.

[0029] Figure 4 shows the case where the angle θ1 formed by the two straight lines forming the shape of the notch 2 is 90°. Angle θ1 should be greater than 90° and less than 180°, and preferably greater than 90° and less than 135°. If angle θ1 falls outside this range, stresses caused by expansion and contraction under severe thermal shock conditions will concentrate on the intersection 4 of the two straight lines, making it more susceptible to cracking.

[0030] FIG4 shows the curve that forms the shape of the notch 2. The radius of curvature R1 of this curve is 0.2 mm or greater, preferably 1 mm or greater, more preferably 2 mm or greater, more preferably 3 mm or greater, and even more preferably 5 mm or greater. If the radius of curvature R1 is less than 0.2 mm, stresses caused by expansion and contraction under severe thermal shock conditions will concentrate on the curved portion, making it more susceptible to cracking.

[0031] The through-holes can be provided within the plane of the polarizing film with the adhesive layer attached. If multiple through-holes are provided within the plane of the polarizing film with the adhesive layer attached, they can have the same or different shapes. The through-holes can be formed by straight lines, curved lines, or a combination thereof. Examples of shapes for the through-holes include circles, ellipses (with one or two axes of symmetry), rounded rectangles, quadrilaterals (squares, rectangles), and polygons with five or more corners.

[0032] Methods for forming the aforementioned irregular portion include, for example, punching, end milling, and laser processing. The aforementioned irregular portion is generally formed by the aforementioned processing after laminating the layers.

[0033] <Polarizing film with adhesive layer> First, the various components constituting the polarizing film with an adhesive layer of the present invention are described. The polarizing film can be a polarizer and a polarizer having a protective film on one or both sides.

[0034] There are no particular limitations on polarizers; various polarizers can be used. Examples include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, and partially saponified ethylene-vinyl acetate copolymer films, which have been adsorbed with a dichroic substance such as iodine or a dichroic dye and then uniaxially stretched. Oriented polyene films such as dehydrated polyvinyl alcohol films and dehydrochlorinated polyvinyl chloride films are also available. Among these, polarizers composed of polyvinyl alcohol films and a dichroic substance such as iodine are particularly suitable. The thickness of these polarizers is not particularly limited, but is generally approximately 80 μm or less.

[0035] Furthermore, thin polarizers with a thickness of 10 μm or less can be used. From the perspective of reducing thickness, a thickness of 1 to 7 μm is preferred. These thin polarizers offer excellent visibility due to minimal thickness variation, and minimal dimensional change, resulting in superior durability. Furthermore, they can also be thinned as polarizing films, making them ideal from these perspectives.

[0036] The protective film can be made of thermoplastic resins that exhibit excellent transparency, mechanical strength, thermal stability, moisture barrier properties, and isotropy. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyether sulfide resins, polysulfide 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. Furthermore, the protective film is typically attached to one side of the polarizer via an adhesive layer, while the protective film on the other side can be made of thermosetting resins such as (meth)acrylic, urethane, acrylic urethane, epoxy, and silicone resins, or UV-curable resins.

[0037] Cellulose resins and (meth)acrylic resins are preferred materials for the protective film (transparent protective film) because they minimize fluctuations in the surface resistance of the adhesive layer. Furthermore, the (meth)acrylic resin preferably uses a (meth)acrylic resin having a lactone ring structure. Examples of (meth)acrylic resins having a lactone ring structure include those described in Japanese Patent Application Laid-Open Nos. 2000-230016, 2001-151814, 2002-120326, 2002-254544, and 2005-146084. Cellulose resins are particularly preferred because they are more effective than (meth)acrylic resins in suppressing irregular cracks and polarizer cracks, which are issues faced in single-sided polarizing film protection.

[0038] The protective film may also be a retardation film, brightness enhancement film, or diffuser film. Examples of retardation films include those with a front retardation of 40 nm or greater and / or a thickness-direction retardation of 80 nm or greater. The front retardation is typically controlled within the range of 40-200 nm, and the thickness-direction retardation is typically controlled within the range of 80-300 nm. When using a retardation film as a protective film, it can also function as a polarizer protective film, allowing for a thinner film.

[0039] The surface of the protective film not in contact with the polarizer may be provided with a functional layer such as a hard coating layer, an anti-reflection layer, an anti-adhesion layer, a diffusion layer, or even an anti-glare layer.

[0040] The protective film and polarizer are laminated together via intermediary layers such as an adhesive layer, a pressure-sensitive adhesive layer, and a primer layer. It is desirable that the intermediary layers allow the two to be laminated without any air gaps. The protective film and polarizer are preferably laminated together via an adhesive layer. The adhesive used to bond the polarizer to the protective film can be any of various types, including aqueous, solvent-based, hot melt, free radical-curing, and cationic-curing adhesives, as long as they are optically transparent. However, aqueous or free radical-curing adhesives are particularly suitable.

[0041] <Adhesive Layer> The adhesive layer is formed of an adhesive composition containing a (meth)acrylic polymer (A) and an ionic compound (B).

[0042] The (meth)acrylic polymer (A) contains an alkyl (meth)acrylate as a main monomer unit. (Meth)acrylate refers to acrylate and / or methacrylate, and (meth) in the present invention is also synonymous.

[0043] The (meth)acrylate 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. Examples of such alkyl groups include methyl, ethyl, propyl, isopropyl, butyl, isobutyl, pentyl, hexyl, cyclohexyl, heptyl, 2-ethylhexyl, isooctyl, nonyl, decyl, isodecyl, dodecyl, isomyristyl, lauryl, tridecyl, pentadecyl, hexadecyl, heptadecyl, and octadecyl. These groups may be used alone or in combination. The average number of carbon atoms in such alkyl groups is preferably 3 to 9.

[0044] The weight ratio of the aforementioned alkyl (meth)acrylate, as a monomer unit, is preferably 70% by weight or greater based on the weight ratio of all monomers (100% by weight) constituting the (meth)acrylic polymer (A). The weight ratio of the aforementioned alkyl (meth)acrylate can be considered as the remainder of other comonomers. When the weight ratio of the aforementioned alkyl (meth)acrylate is within the aforementioned range, it is preferred to ensure good adhesion.

[0045] In order to improve adhesion and heat resistance, in addition to the aforementioned alkyl (meth)acrylate monomer units, one or more comonomers having a polymerizable functional group 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.

[0046] Examples of the comonomer include functional group-containing monomers such as carboxyl group-containing monomers, hydroxyl group-containing monomers, and amide group-containing monomers.

[0047] A carboxyl-containing monomer is a compound containing a carboxyl group and a polymerizable unsaturated double bond, such as a (meth)acryl group or a vinyl group, within its structure. Specific examples of carboxyl-containing monomers include (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid. Of these carboxyl-containing monomers, acrylic acid is preferred from the perspectives of copolymerizability, cost, and adhesive properties.

[0048] A hydroxyl-containing monomer is a compound containing a hydroxyl group and a polymerizable unsaturated double bond, such as a (meth)acryloyl group or a vinyl group, within its structure. Specific examples of hydroxyl-containing monomers include hydroxyalkyl (meth)acrylates such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, and 12-hydroxylauryl (meth)acrylate, or (4-hydroxymethylcyclohexyl)-methacrylate. From the perspective of durability, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred among the aforementioned hydroxyl-containing monomers, with 4-hydroxybutyl (meth)acrylate being particularly preferred.

[0049] Carboxyl- and hydroxyl-containing monomers serve as reaction sites for crosslinkers when the adhesive composition contains one. Carboxyl- and hydroxyl-containing monomers exhibit high intermolecular reactivity with crosslinkers, making them suitable for enhancing the cohesiveness and heat resistance of the resulting adhesive layer. Furthermore, carboxyl- and hydroxyl-containing monomers are preferred for achieving both durability and workability, while hydroxyl-containing monomers are preferred for workability.

[0050] 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 even more preferably 0.1 to 5% by weight. A weight ratio of 0.01% by weight or greater is preferred from the perspective of durability. On the other hand, a weight ratio exceeding 10% by weight is undesirable from the perspective of workability.

[0051] The weight ratio of the hydroxyl-containing monomer is preferably 3% by weight or less, preferably 0.01 to 3% by weight, more preferably 0.1 to 2% by weight, and even more preferably 0.2 to 2% by weight. From the perspective of the cross-linked adhesive layer, durability, or adhesive properties, the weight ratio of the hydroxyl-containing monomer is preferably 0.01% by weight or greater. On the other hand, a ratio exceeding 3% by weight is undesirable from the perspective of durability.

[0052] Amide group-containing monomers are compounds containing an amide group in their structure and containing polymerizable unsaturated double bonds such as (meth)acrylamide and vinyl groups. 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, Examples of suitable monomers include acrylamide monomers such as (methyl)acrylamide, aminoethyl (meth)acrylamide, mercaptomethyl (meth)acrylamide, and mercaptoethyl (meth)acrylamide; N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine, and N-(meth)acryloylpyrrolidine; and N-vinyl lactam-containing monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam. Amide-containing monomers are preferred because they can suppress the increase in surface resistance over time (especially in humid environments) and meet durability requirements. They are also preferred because they can suppress irregular cracks. Among amide-containing monomers, N-vinyl lactam-based monomers are particularly preferred because they can suppress the increase in surface resistance over time (especially in humid environments), meet the durability requirements of the transparent conductive layer (touch sensor layer), and prevent irregular cracks.

[0053] A high weight ratio of the amide-containing monomer tends to reduce its anchoring properties on the optical film. Therefore, the weight ratio is preferably 10% by weight or less, and more preferably 5% by weight or less. To suppress the increase in surface resistivity over time (especially in a humid environment), the weight ratio of the amide-containing monomer is preferably 0.1% by weight or greater. The weight ratio is preferably 0.3% by weight or greater, and more preferably 0.5% by weight or greater. The amide-containing monomer is particularly suitable in relation to the ionic compound (B) contained in the adhesive layer of the present invention.

[0054] In the adhesive composition used to form the adhesive layer, the presence of amide groups introduced into the side chains of the (meth)acrylic polymer (A) of the base polymer is preferred because the presence of these amide groups can suppress the viscosity adjusted by the addition of the ionic compound (B) and maintain it within the desired range even under humid conditions. It is believed that the presence of amide groups introduced into the side chains of the (meth)acrylic polymer (A) as functional groups of comonomers can enhance the compatibility between the (meth)acrylic polymer (A) and the ionic compound (B).

[0055] Furthermore, the adhesive layer, when containing amide groups introduced into the side chains of the (meth)acrylic polymer (A) of the base polymer, exhibits excellent durability against both glass and transparent conductive layers (such as ITO layers), suppressing peeling and bulging when attached to a liquid crystal panel. Furthermore, satisfactory durability is maintained even in humid environments (after humidity reliability testing).

[0056] Alternatively, an aromatic ring-containing (meth)acrylate can be used as a comonomer. Aromatic ring-containing (meth)acrylate is a compound containing an aromatic ring structure and a (meth)acryloyl group. Examples of the aromatic ring include a benzene ring, a naphthalene ring, and a biphenyl ring.

[0057] Specific examples of the aromatic ring-containing (meth)acrylate 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-3-phenoxypropyl (meth)acrylate, methoxybenzyl (meth)acrylate, chlorobenzyl (meth)acrylate, cresol (meth)acrylate, polystyrene (meth)acrylate, and the like; those having a naphthalene ring, such as hydroxyethylated β-naphthol acrylate, 2-naphthol ethyl (meth)acrylate, 2-naphthyloxyethyl acrylate, 2-(4-methoxy-1-naphthyloxy)ethyl (meth)acrylate; and those having a biphenyl ring, such as biphenyl (meth)acrylate.

[0058] From the viewpoint of adhesion and durability, the aromatic ring-containing (meth)acrylate is preferably benzyl (meth)acrylate or phenoxyethyl (meth)acrylate, and particularly phenoxyethyl (meth)acrylate.

[0059] 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. A weight ratio of 3% by weight or greater of the aromatic ring-containing (meth)acrylate is preferred for suppressing display unevenness. On the other hand, a weight ratio exceeding 25% by weight may result in insufficient suppression of display unevenness and a tendency for reduced durability.

[0060] Specific examples of other comonomers other than those mentioned above include anhydride group-containing monomers such as maleic anhydride and itaconic anhydride; caprolactone adducts of acrylic acid; sulfonic acid group-containing monomers such as allylsulfonic acid, 2-(meth)acrylamido-2-methylpropanesulfonic acid, (meth)acrylamidopropanesulfonic acid, and sulfopropyl (meth)acrylate; and phosphate group-containing monomers such as 2-hydroxyethylacryloyl phosphate.

[0061] Examples of monomers for 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, and N-(meth)acryloyloxymethylenesuccinimide. Succinimide monomers such as (1,2-dimethylamino)acryl-8-oxyoctamethylenesuccinimide; 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.

[0062] Modifying monomers may also include vinyl monomers such as vinyl acetate and vinyl propionate; cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; epoxy-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; and (meth)acrylate monomers such as tetrahydrofurfuryl (meth)acrylate, fluoro(meth)acrylate, polysilicone (meth)acrylate, and 2-methoxyethyl acrylate. Further examples include isoprene, butadiene, isobutylene, and vinyl ether.

[0063] In addition, copolymerizable monomers other than the above-mentioned monomers include silane monomers containing silicon atoms. Examples of silane monomers include 3-acryloxypropyltriethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, 4-vinylbutyltrimethoxysilane, 4-vinylbutyltriethoxysilane, 8-vinyloctyltrimethoxysilane, 8-vinyloctyltriethoxysilane, 10-methacryloxydecyltrimethoxysilane, 10-acryloxydecyltrimethoxysilane, 10-methacryloxydecyltriethoxysilane, and 10-acryloxydecyltriethoxysilane.

[0064] Furthermore, as the comonomer, 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, trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol penta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, and the like can also be used. Polyfunctional monomers having two or more unsaturated double bonds such as (meth)acryloyl or vinyl groups, such as esters of (meth)acrylic acid and polyols, such as esters of (meth)acrylic acid, dipentatriol hexa(meth)acrylate modified with caprolactone, or polyester (meth)acrylates, epoxy (meth)acrylates, urethane (meth)acrylates, etc., having two or more unsaturated double bonds such as (meth)acryloyl or vinyl groups added to the backbone of polyesters, epoxy, urethane, etc. as the same functional groups as the monomer components.

[0065] The ratio of the aforementioned other comonomers in the (meth)acrylic polymer (A) is preferably about 0 to 10 wt %, more preferably about 0 to 7 wt %, and more preferably about 0 to 5 wt %, based on the weight ratio of all the constituent monomers (100 wt %) of the (meth)acrylic polymer (A).

[0066] The (meth)acrylic polymer (A) of the present invention generally has a weight-average molecular weight of 1,000,000 to 2,500,000. Considering durability, especially heat resistance, the weight-average molecular weight is preferably 1,200,000 to 2,000,000. From the perspective of heat resistance, a weight-average molecular weight of 1,000,000 or greater is preferred. A weight-average molecular weight exceeding 2,500,000 tends to harden the adhesive, making it susceptible to peeling. Furthermore, the weight-average molecular weight (Mw) / number-average molecular weight (Mn), which represents the molecular weight distribution, is preferably 1.8 or greater and 10 or less, more preferably 1.8 to 7, and even more preferably 1.8 to 5. A molecular weight distribution (Mw / Mn) exceeding 10 is undesirable from the perspective of durability. The weight-average molecular weight and molecular weight distribution (Mw / Mn) are determined by GPC (gel permeation chromatography) and are calculated in terms of polystyrene.

[0067] The (meth)acrylic polymer (A) can be produced by appropriately selecting a known production method such as solution polymerization, bulk polymerization, emulsion polymerization, or various free radical polymerization methods. Furthermore, the resulting (meth)acrylic polymer (A) may be any of a random copolymer, a block copolymer, and a graft copolymer.

[0068] In solution polymerization, the polymerization solvent may be ethyl acetate, toluene, or the like. Specifically, solution polymerization can be performed under a stream of an inert gas such as nitrogen, with the addition of a polymerization initiator. The reaction is typically conducted at approximately 50-70°C for 5-30 hours.

[0069] The polymerization initiator, chain transfer agent, emulsifier, etc. used in the free radical polymerization are not particularly limited and may be appropriately selected and used. Furthermore, the weight average molecular weight of the (meth)acrylic polymer (A) can be controlled by adjusting the amount of polymerization initiator and chain transfer agent used and the reaction conditions. The amount used can be appropriately adjusted depending on the type of these agents.

[0070] <Ionic Compound (B)> The ionic compound (B) contained in the adhesive composition forming the adhesive layer of the present invention has a cationic component having a molecular weight of 210 or less. To suppress the occurrence of irregular cracks, the molecular weight of the cationic component is preferably 150 or less, more preferably 110 or less, even more preferably 50 or less, and even more preferably 10 or less. A higher molecular weight of the cationic component inhibits entanglement between the (meth)acrylic polymers in the adhesive layer, tending to soften the adhesive layer's physical properties. Therefore, a lower molecular weight reduces the likelihood of softening the adhesive layer's physical properties, thus suppressing irregular cracks. Furthermore, a lower molecular weight of the cationic component is preferred because it reduces the surface resistivity of the adhesive layer, thereby suppressing static unevenness.

[0071] Furthermore, the ionic compound (B) can preferably be an alkali metal salt and / or an organic cation-anion salt. Alkali metal salts include organic and inorganic alkali metal salts. In the present invention, "organic cation-anion salt" refers to an organic salt whose cation component is composed of an organic substance, and whose anion component can be either organic or inorganic. "Organic cation-anion salt" is also referred to as an ionic liquid or an ionic solid. By incorporating the ionic compound (B) into the adhesive layer, the surface resistance of the adhesive layer can be reduced, thereby suppressing the generation of static electricity. This can prevent static electricity from disrupting the alignment of the liquid crystal layer and causing light leakage (uneven charging).

[0072] <Alkali Metal Salt> Examples of the alkali metal ions constituting the cationic component of the alkali metal salt include lithium, sodium, and potassium ions. Among these alkali metal ions, lithium ion is preferred.

[0073] The anion component of the alkali metal salt may be composed of an organic substance or an inorganic substance. Examples of the anion component constituting the organic salt include 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): (C nF 2n+1SO 2) 2N - (however, n is an integer from 0 to 10), (2): CF 2(C mF 2mSO 2) 2N - (where m is an integer from 1 to 10), (3): -O 3S(CF 2) lSO 3 -(however, l is an integer from 1 to 10), (4):(C pF 2p+1SO 2)N -(C qF 2q+1SO 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 produce ionic compounds with excellent ion dissociation. Examples of anionic components constituting inorganic salts include Cl-, Br-, I-, AlCl4-, Al2Cl7-, BF4-, PF6-, ClO4-, NO3-, AsF6-, SbF6-, NbF6-, TaF6-, and (CN)2N-. Preferred anionic components are (perfluoroalkylsulfonyl)imides represented by the aforementioned general formula (1), such as (CF3SO2)2N- and (C2F5SO2)2N-, with (trifluoromethanesulfonyl)imides represented by (CF3SO2)2N- being particularly preferred.

[0074] Specific examples of organic salts of alkali metals include sodium acetate, sodium alginate, sodium lignosulfonate, sodium toluenesulfonate, LiCF3SO3, Li(CF3SO2)2N, Li(CF3SO2)2N, Li(C2F5SO2)2N, Li(C4F9SO2)2N, Li(CF3SO2)3C, KO3S(CF2)3SO3K, and LiO3S(CF2)3SO3K. Among them, LiCF3SO3, Li(CF3SO2)2N, Li(C2F5SO2)2N, Li(C4F9SO2)2N, and Li(CF3SO2)3C are preferred. Li(CF3SO2)2N, Li(C2F5SO2)2N, and Li(C4F9SO2)2N are also preferred. Fluorine-containing lithium imide salts such as bis(fluorosulfonyl)imide lithium salts such as Li(C₄F₆SO₂)₂N and Li(C₄F₆SO₂)₂N are preferred, with lithium (perfluoroalkylsulfonyl)imide salts being particularly preferred. Other examples include 4,4,5,5-tetrafluoro-1,3,2-ditetrahydrothiazolidine-1,1,3,3-tetraoxide lithium salt.

[0075] Examples of inorganic salts of alkali metals include lithium perchlorate and lithium iodide.

[0076] <Organic cation-anion salt> The organic cation-anion salt used in the present invention is composed of a cationic component and an anionic component, wherein the cationic component is organic. Specific examples of the cationic component include pyridinium cations, piperidinium cations, pyrrolidinium cations, cations with a dihydropyrrole skeleton, cations with a pyrrole skeleton, imidazolium cations, tetrahydropyrimidinium cations, dihydropyrimidinium cations, pyrazolium cations, pyrazolinium cations, tetraalkylammonium cations, trialkylsonium cations, and tetraalkylphosphonium cations.

[0077] Examples of anion components that can be used include Cl-, Br-, I-, AlCl4-, Al2Cl7-, BF4-, PF6-, ClO4-, NO3-, CH3COO-, CF3COO-, CH3SO3-, CF3SO3-, (CF3SO2)3C-, AsF6-, SbF6-, NbF6-, TaF6-, (CN)2N-, C4F9SO3-, C3F7COO-, ((CF3SO2)(CF3CO)N-, -O3S(CF2)3SO3-, and those represented by the following general formulas (1) to (4): (1): (C nF 2n+1SO 2) 2N - (however, n is an integer from 0 to 10), (2): CF 2(C mF 2mSO 2) 2N - (where m is an integer from 1 to 10), (3): -O 3S(CF 2) lSO 3 -(however, l is an integer from 1 to 10), (4):(C pF 2p+1SO 2)N -(C qF 2q+1SO 2) (However, p and q are integers from 1 to 10). Among them, anionic components containing fluorine atoms are particularly suitable for use because they can provide ionic compounds with good ion dissociation properties.

[0078] 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 methyltrioctylammonium bis(trifluoromethanesulfonyl)imide, 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide, and ethylmethylimidazolium bis(fluorosulfonyl)imide. Among them, 1-methyl-1-propylpyrrolidinium bis(trifluoromethanesulfonyl)imide and ethylmethylimidazolium bis(fluorosulfonyl)imide are more preferred.

[0079] In addition, the ionic compound (B) includes, in addition to the aforementioned alkali metal salts and organic cation-anion salts, inorganic salts such as ammonium chloride, aluminum chloride, cupric chloride, ferrous chloride, ferric chloride, and ammonium sulfate.

[0080] When the 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. Therefore, alkali metal salts containing these alkali metal ions as cationic components are preferably used. In particular, from the perspective of compatibility with the adhesive layer, organic salts of alkali metals whose anionic components are composed of organic substances are preferred. Furthermore, the alkali metal ion is preferably a lithium ion, which has the smallest molecular weight. The ionic compound (B) is preferably a lithium salt, and an organic lithium salt is particularly preferred. On the other hand, when the ionic compound (B) is an organic cation-anion salt, it is preferably selected from the cation components listed above and having a molecular weight of 210 or less. In particular, from the perspective of compatibility with the adhesive layer, organic cation-anion salts whose anionic components are composed of organic substances are preferred.

[0081] The ratio of the ionic compound (B) in the adhesive composition of the present invention should be appropriately adjusted to meet the antistatic properties of the adhesive layer and the sensitivity of the touch panel. For example, to achieve a surface resistance of the adhesive layer within the range of 1.0×10⁻¹⁰ to 1.0×10⁻¹² Ω / □, the ratio of the ionic compound (B) should be adjusted according to the type of LCD panel with built-in touch sensing functionality, taking into account factors such as the type of protective film used for the polarizing film. For example, in the embedded touch sensing LCD panel shown in Figure 6, the initial surface resistance of the adhesive layer should be controlled within the range of 1×10⁻¹⁰ to 6×10⁻¹² Ω / □. Furthermore, in the semi-in-cell LCD panel shown in Figure 7 or the top-mounted LCD panel with built-in touch sensing functionality shown in Figure 8, the initial surface resistance of the adhesive layer should be controlled within the range of 1×10⁻¹⁰ to 1×10⁻¹² Ω / □.

[0082] If the amount of the ionic compound (B) increases, it may precipitate, potentially causing moisture peeling. Furthermore, if the amount of the ionic compound (B) increases, the surface resistance may become too low, leading to baseline fluctuations (which may cause touch malfunctions due to the low surface resistance), potentially reducing the sensitivity of the touch panel. The ratio of the ionic compound (B), for example, to 100 parts by weight of the (meth)acrylic polymer (A), is generally preferably 40 parts by weight or less, more preferably 20 parts by weight or less, and most preferably 13 parts by weight or less. Too little may lead to poor antistatic properties, while too much may reduce touch sensitivity, lead to ionic compound precipitation, and worsen moisture peeling of the adhesive. On the other hand, to improve antistatic performance, it is desirable to use 0.1 parts by weight or more of the ionic compound (B). Based on this perspective, the amount of the ionic compound (B) is preferably 1 part by weight or more, and more preferably 5 parts by weight or more.

[0083] The adhesive composition of the present invention may contain a crosslinking agent (C). As the crosslinking agent (C), an organic crosslinking agent or a polyfunctional metal chelate can be used. Examples of organic crosslinking agents include isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. A polyfunctional metal chelate is a compound in which a polyvalent metal is covalently or coordinately bonded to an organic compound. 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 in the organic compound that can be covalently or coordinately bonded include oxygen atoms, and examples of the organic compound include alkyl esters, alcohol compounds, carboxylic acid compounds, ether compounds, and ketone compounds.

[0084] The crosslinking agent (C) is preferably an isocyanate crosslinking agent and / or a peroxide crosslinking agent.

[0085] The isocyanate crosslinking agent (C) can be a compound having at least two isocyanate groups. For example, aliphatic polyisocyanates, alicyclic polyisocyanates, and aromatic polyisocyanates commonly used in urethanization reactions are generally used.

[0086] Any peroxide that generates free radical species upon heating or light exposure, thereby cross-linking the base polymer of the adhesive composition, can be used. 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.

[0087] Peroxides that can be used include di(2-ethylhexyl) peroxydicarbonate (1 minute half-life temperature: 90.6°C), di(4-tert-butylcyclohexyl) peroxydicarbonate (1 minute half-life temperature: 92.1°C), di-tert-butyl peroxydicarbonate (1 minute half-life temperature: 92.4°C), tert-butyl peroxyneodecanoate (1 minute half-life temperature: 103.5°C), tert-hexyl peroxypivalate (1 minute half-life temperature: 109.1°C), tert-butyl peroxypivalate (1 minute half-life temperature: 110.3°C), dilauryl peroxide (1 minute half-life temperature: 112.1°C), and di-tert-butyl peroxydicarbonate (1 minute half-life temperature: 112.1°C). half-life temperature: 116.4°C), di-n-octyl peroxide (1-minute half-life temperature: 117.4°C), 1,1,3,3-tetramethylbutyl peroxy-2-ethylhexanoate (1-minute half-life temperature: 124.3°C), di(4-methylbenzyl) peroxide (1-minute half-life temperature: 128.2°C), dibenzyl peroxide (1-minute half-life temperature: 130.0°C), tert-butyl perisobutyrate (1-minute half-life temperature: 136.1°C), 1,1-bis(tert-hexylperoxy)cyclohexane (1-minute half-life temperature: 149.2°C), 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), and diphenylformyl peroxide (1-minute half-life temperature: 130.0°C) are particularly suitable from the perspective of excellent cross-linking reaction efficiency.

[0088] The amount of the crosslinking agent (C) used per 100 parts by weight of the (meth)acrylic polymer (A) 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. If the crosslinking agent (C) content is less than 0.01 parts by weight, the adhesive layer may not be sufficiently crosslinked, resulting in insufficient durability or adhesive properties. On the other hand, if the content exceeds 3 parts by weight, the adhesive layer may become too hard, tending to reduce durability.

[0089] The adhesive composition of the present invention may contain a silane coupling agent (D). By using the silane coupling agent (D), durability can be improved. 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; and silane coupling agents containing isocyanate groups such as 3-isocyanatepropyltriethoxysilane. The silane coupling agents exemplified above are preferably silane coupling agents containing epoxy groups.

[0090] Furthermore, silane coupling agents (D) containing multiple alkoxysilyl groups within the molecule can also be used. Specific examples include X-41-1053, X-41-1059A, X-41-1056, X-41-1805, X-41-1818, X-41-1810, and X-40-2651 manufactured by Shin-Etsu Chemical Co., Ltd. These silane coupling agents containing multiple alkoxysilyl groups within the molecule are less volatile and are therefore more suitable for improving durability. Durability is particularly good when the adherend of the optical film to be attached is a transparent conductive layer (such as ITO), which is less reactive with alkoxysilyl groups than glass. Furthermore, silane coupling agents containing multiple alkoxysilyl groups within the molecule preferably also contain epoxy groups, and more preferably, multiple epoxy groups within the molecule. Silane coupling agents containing multiple alkoxysilyl groups and epoxy groups within their molecules tend to exhibit good durability even when the adherend is a transparent conductive layer (e.g., ITO). Specific examples of silane coupling agents containing multiple alkoxysilyl groups and epoxy groups include X-41-1053, X-41-1059A, and X-41-1056 manufactured by Shin-Etsu Chemical Co., Ltd., with X-41-1056 manufactured by Shin-Etsu Chemical Co., Ltd. being particularly preferred due to its high epoxy group content.

[0091] The silane coupling agent (D) may be used alone or as a mixture of two or more. The total content of the silane coupling agent (D) 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 most preferably 0.05 to 0.6 parts by weight, per 100 parts by weight of the (meth)acrylic polymer (A). This amount can improve durability.

[0092] The adhesive composition of the present invention may also contain other known additives, such as polyether compounds containing reactive silicon groups, polyether compounds of polyalkylene glycols such as polypropylene glycol, colorants, pigment powders, dyes, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, softeners, antioxidants, anti-aging agents, light stabilizers, UV absorbers, polymerization inhibitors, inorganic or organic fillers, metal powders, particles, or foils, depending on the intended use. Furthermore, a redox system in which a reducing agent is added may be employed within a controllable range. The amount of these additives is preferably 5 parts by weight or less, more preferably 3 parts by weight or less, and even more preferably 1 part by weight or less, relative to 100 parts by weight of the (meth)acrylic polymer (A).

[0093] The adhesive layer can be formed by, for example, applying the adhesive composition to a release member that has been subjected to a peeling treatment, drying to remove the polymerization solvent, etc., forming an adhesive layer, and then transferring the adhesive layer to an optical film (polarizing film); or applying the adhesive composition to an optical film (polarizing film), drying to remove the polymerization solvent, etc., to form an adhesive layer on the optical film. Furthermore, one or more solvents other than the polymerization solvent may be added as appropriate during adhesive application.

[0094] 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.

[0095] The adhesive layer used in the polarizing film with an adhesive layer according to the present invention, from the perspective of application to profiled polarizing films, should preferably have a creep value of 120 μm or less at 85°C, preferably 100 μm or less, more preferably 85 μm or less, and even more preferably 60 μm or less. The lower limit of the creep value is preferably 15 μm or greater, more preferably 30 μm or greater. A creep value greater than 120 μm may worsen the cracks that occur in the profiled polarizing film, as described in the examples. A creep value less than 15 μm may reduce the stress relaxation properties of the adhesive layer, potentially leading to peeling of the adhesive layer during durability testing.

[0096] <Transparency Layer> The transparent layer will be described in detail below.

[0097] From the perspectives of thinness 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, even more preferably 1.5 μm or less, and even more preferably 1 μm or less. Excessively thick transparent layers increase the thickness of the polarizing film, potentially reducing the optical reliability of the polarizer. On the other hand, from the perspective of minimizing the fluctuation in the surface resistance of the adhesive layer, the thickness of the transparent layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, and even more preferably 0.3 μm or more.

[0098] The material forming the transparent layer can be transparent and can suppress the influence of the adhesive layer on the polarizer. For example, the material can be a material forming a urethane prepolymer (a) containing a reaction product of an isocyanate compound and a polyol.

[0099] The isocyanate compound is preferably a polyfunctional isocyanate compound, and specifically includes polyfunctional aromatic isocyanate compounds, alicyclic isocyanates, aliphatic isocyanate compounds, or dimers thereof.

[0100] Examples of the polyfunctional aromatic isocyanate compound include phenylene diisocyanate, 2,4-tolyl isocyanate, 2,6-tolyl 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, succinyl diisocyanate, methylene bis-4-phenyl isocyanate, and p-phenylene diisocyanate.

[0101] Examples of the polyfunctional alicyclic isocyanate compound include 1,3-cyclopentene diisocyanate, 1,3-cyclohexane diisocyanate, 1,4-cyclohexane diisocyanate, 1,3-bisisocyanatomethylcyclohexane, isophorone diisocyanate, hydrogenated diphenylmethane diisocyanate, hydrogenated stilbene diisocyanate, hydrogenated toluene diisocyanate, and hydrogenated tetramethylstilbene diisocyanate.

[0102] Examples of the polyfunctional aliphatic isocyanate compound include trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, pentamethylene diisocyanate, 1,2-propylene diisocyanate, 1,3-butylene diisocyanate, dodecamethylene diisocyanate, and 2,4,4-trimethylhexamethylene diisocyanate.

[0103] Examples of the polyfunctional isocyanate compound include tris(6-isocyanatehexyl)isocyanurate and the like having three or more isocyanate groups.

[0104] Examples of the polyol include ethylene glycol, diethylene glycol, 1,3-butanediol, 1,4-butanediol, neopentyl glycol, 3-methylene-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-methylene-1,8-octanediol, 1,8-decanediol, octadecanediol, glycerol, trimethylolpropane, pentaerythritol, hexanetriol, and polypropylene glycol.

[0105] In the present invention, the urethane prepolymer (a) preferably has a rigid structure in which cyclic structures (such as benzene rings, cyanurate rings, and isocyanurate rings) account for a large proportion of the molecular structure. For example, the polyfunctional isocyanate compound may be used alone or in combination of two or more. However, aromatic isocyanate compounds are preferred to suppress the infiltration of moisture into the polarizer. Other polyfunctional isocyanate compounds may also be used in combination with aromatic isocyanate compounds. Among aromatic isocyanate compounds, at least one selected from toluene diisocyanate and diphenylmethane diisocyanate is particularly preferred.

[0106] Urethane prepolymer (a) preferably uses trimethylolpropane-tris-tolyl isocyanate or trimethylolpropane-tris-diphenylmethane diisocyanate. The urethane prepolymer (a) is a compound having terminal isocyanate groups and can be obtained, for example, by mixing an isocyanate compound with a polyol and then stirring and reacting them. It is generally preferred to mix the isocyanate compound with the polyol so that the isocyanate groups are in excess relative to the hydroxyl groups of the polyol.

[0107] Alternatively, the urethane prepolymer (a) may be one in which the terminal isocyanate groups have been provided with protecting groups. Examples of such protecting groups include oximes and lactamides. The isocyanate groups are protected by heating to dissociate the protecting groups from the isocyanate groups, allowing the isocyanate groups to react.

[0108] The material forming the transparent layer may contain, in addition to the aforementioned urethane prepolymer (a), a compound (b) having at least two functional groups with active hydrogen atoms reactive with isocyanate groups. Examples of such functional groups with active hydrogen atoms reactive with isocyanate groups include hydroxyl groups and amino groups. The greater the number of active hydrogen atoms in the aforementioned compound (b), the more reactive points there are with the isocyanate groups in the urethane prepolymer (a), making it easier to form a cured product. Therefore, the number of such functional groups is preferably three or more.

[0109] Furthermore, the value obtained by dividing the molecular weight of the compound (b) by the number of functional groups is preferably 350 or less. By defining the relationship between the molecular weight and the number of functional groups in this manner, the reactivity of the compound (b) with the isocyanate groups of the urethane prepolymer (a) can be ensured.

[0110] 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 perspective of compatibility when the compound (b) is prepared in solution with the urethane prepolymer (a) to form a material.

[0111] Examples of the compound (b) include polyols, polyamines, and compounds having a hydroxyl group and an amino group in the molecule.

[0112] Examples of the polyol include bifunctional 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 trimethylolpropane; and tetrafunctional alcohols such as neopentyltol, hexanetriol, and sorbitol. Other examples include adducts of alkylene oxides (e.g., propylene oxide) added to the above polyols such as polyoxypropylene glycerol ether, polyoxypropylene trimethylolpropane ether, and polyoxypropylene sorbitol ether.

[0113] Examples of the polyamine include ethylenediamine, propylenediamine, hexamethylenediamine, diethylenetriamine, triethylenetetramine, isophoronediamine, dicyclohexylmethane-4,4′-diamine, and dimer diamine.

[0114] Examples of compounds having hydroxyl groups and amino groups in the molecule include diamines having hydroxyl groups in the molecule, such as 2-hydroxyethylethylenediamine, 2-hydroxyethylpropylenediamine, di-2-hydroxyethylethylenediamine, di-2-hydroxyethylpropylenediamine, 2-hydroxypropylethylenediamine, and di-2-hydroxypropylethylenediamine; and alkanolamines, such as ethanolamine, diethanolamine, and triethanolamine.

[0115] The compound (b) is preferably a polyol from the viewpoint of preventing deterioration of the optical reliability of the polarizer, and trimethylolpropane is particularly preferred from the viewpoint of reactivity with the urethane prepolymer (a).

[0116] The forming material contains the urethane prepolymer (a) as a main component. The urethane prepolymer (a) preferably accounts for 50% by weight or more of the solid content of the forming material.

[0117] The blending ratio of the compound (b) to the urethane prepolymer (a) is preferably 5% by weight or greater, relative to 100% by weight (solid content) of the combined urethane prepolymer (a) and the compound (b). To improve film strength, the blending ratio of the compound (b) is preferably 10% by weight or greater. On the other hand, a higher blending ratio of the compound (b) may deteriorate the optical reliability of the polarizer. Therefore, the blending ratio of the compound (b) is preferably 80% by weight or less, and more preferably 50% by weight or less.

[0118] The aforementioned forming material may further contain a reaction catalyst to enhance the reactivity of the isocyanate group. The reaction catalyst is not particularly limited, but is preferably a tin-based catalyst or an amine-based catalyst. One or more reaction catalysts may be used. The amount of reaction catalyst used is generally 5 parts by weight or less relative to 100 parts by weight of the urethane prepolymer (a). Excessive amounts of reaction catalyst accelerate the crosslinking reaction, causing the forming material to foam. However, using the foamed forming material will not provide sufficient adhesion. Generally, the reaction catalyst is preferably used in an amount of 0.01 to 5 parts by weight, more preferably 0.05 to 4 parts by weight.

[0119] A reaction catalyst may also be used to increase the reactivity of the isocyanate group. The reaction catalyst is not particularly limited, but preferably a tin-based catalyst or an amine-based catalyst. One or more reaction catalysts may be used. The amount of reaction catalyst used is generally 5 parts by weight or less per 100 parts by weight of the urethane prepolymer. Excessive amounts of reaction catalyst accelerate the crosslinking reaction, causing the prepolymer to foam. However, the foamed prepolymer may not exhibit sufficient adhesion. Generally, the reaction catalyst is preferably used in an amount of 0.01 to 5 parts by weight, more preferably 0.05 to 4 parts by weight.

[0120] Tin catalysts can be either inorganic or organic, with organic catalysts being 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 or alicyclic groups with a backbone such as a methyl, ethyl, ether, or ester group. Examples include tetra-n-butyltin, tri-n-butyltin acetate, n-butyltin trichloride, trimethyltin hydroxide, dimethyltin dichloride, and dibutyltin dilaurate.

[0121] Furthermore, there is no particular limitation on the amine catalyst. Organic groups such as pyridine, amidine, and diazabicycloundecene can be used as catalysts. Other examples of amine-based catalysts include triethylamine. Other examples of reaction catalysts other than those mentioned above include cobalt naphthenate and benzyltrimethylammonium hydroxide.

[0122] 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-based solution or an aqueous solution such as an emulsion, colloidal dispersion, or aqueous solution.

[0123] There are no particular limitations on the organic solvent, as long as it does not have a functional group containing active hydrogen that is reactive with an isocyanate group and can uniformly dissolve the urethane prepolymer (a) and the compound (b) that constitute the forming material. One organic solvent may be used alone or in combination of two or more. Furthermore, different organic solvents may be used for the urethane prepolymer (a) and the compound (b). In this case, the forming material may be prepared by mixing the solutions after preparing them. The viscosity of the prepared forming material may be adjusted by further adding an organic solvent. Furthermore, in the case of a solvent-based solution containing a solution dissolved in an organic solvent, the solution may contain alcohols or water, as exemplified below, as a solvent.

[0124] Examples of the organic solvent 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; halogenated hydrocarbons such as 1,2-dichloroethane; ethers such as methyl tertiary butyl ether; and ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, cyclopentanone, and acetylacetone.

[0125] Furthermore, when preparing an aqueous solution, alcohols such as n-butanol and isopropanol, or ketones such as acetone, may be added. This can be achieved by using a dispersant, or by introducing functional groups with low reactivity with isocyanate groups, such as carboxylates, sulfonates, or quaternary ammonium salts, or water-dispersible components such as polyethylene glycol, into the urethane prepolymer.

[0126] In addition to the aforementioned urethane prepolymer, materials for forming the transparent layer may include cyanoacrylate-based materials, epoxy-based materials, urethane acrylate-based materials, and the like.

[0127] The transparent layer can be formed by appropriately selecting the type of material used. For example, the transparent layer can be formed by applying the material to a polarizer, etc., and then curing the material, thereby forming a coated layer. Generally, this is achieved by drying the material at approximately 30-100°C, preferably 50-80°C, for approximately 0.5-15 minutes after coating to form a cured layer. Furthermore, when the material contains an isocyanate component, an annealing treatment at approximately 30-100°C, preferably 50-80°C, for approximately 0.5-24 hours may be performed to promote the reaction.

[0128] <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 components 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 displays, electroluminescent (EL) displays, plasma displays (PDs), and field emission displays (FEDs).

[0129] The polarizing film with an adhesive layer of the present invention has a small variation ratio of the surface resistance value and is suitable for use in liquid crystal panels with built-in touch sensing functions.

[0130] In addition to the above-mentioned structure, optical films such as phase difference film, viewing angle compensation film, and brightness enhancement film can also be appropriately set in the liquid crystal panel.

[0131] The liquid crystal layer is not particularly limited, and any type, such as TN, STN, π, VA, or IPS, can be used. The transparent substrate 9 (on the light source side) is not particularly limited in material as long as it is transparent, and examples thereof include glass and transparent resin film substrates. Examples of the transparent resin film substrate include those mentioned above.

[0132] 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.

[0133] Specific examples of the aforementioned LCD panel with built-in touch sensing functionality are shown in Figures 6 through 8 . Figures 6 through 8 illustrate the polarizing film with an adhesive layer of the present invention, where the polarizing film 1 with an adhesive layer shown in Figure 1 is applied to the viewing side of the liquid crystal cell. That is, the single-sided protective polarizing film 11 and adhesive 21 in Figure 1 are represented as the first polarizing film 11 and the first adhesive layer 21 in Figures 6 through 8 .

[0134] Figure 6 shows a so-called built-in touch-sensing LCD panel. From the viewing side, the structure comprises: first polarizing film 11 / first adhesive layer 21 / first transparent substrate 41 / touch sensor portion 5 / liquid crystal layer 3 / drive electrode / sensor portion 6 / second transparent substrate 42 / second adhesive layer 22 / second polarizing film 12. In the built-in touch-sensing LCD panel shown in Figure 6, for example, liquid crystal cell C includes the touch sensor portion 5 and the drive electrode / sensor portion 6 within the first and second glass substrates 41 and 42 sandwiching the liquid crystal layer 3 (inside the liquid crystal cell).

[0135] FIG7 shows a modified example of a so-called built-in (semi-built-in) LCD panel with an in-cell touch sensor function. The structure, from the viewing side, comprises: first polarizing film 11 / first adhesive layer 21 / touch sensor portion 5 / first transparent substrate 41 / liquid crystal layer 3 / drive electrode / sensor portion 6 / second transparent substrate 42 / second adhesive layer 22 / second polarizing film 12. In the built-in LCD panel with an in-cell touch sensor function shown in FIG7 , for example, the liquid crystal cell C is located outside the first transparent substrate 41, the touch sensor portion 5 is in direct contact with the first adhesive layer 21, and the liquid crystal cell C has the drive electrode / sensor portion 6 on the second transparent substrate 42 side within the first and second glass substrates 41 and 42 sandwiching the liquid crystal layer 3 (inside the liquid crystal cell).

[0136] FIG8 shows a so-called top-mounted in-cell touch sensing LCD panel. The structure, from the viewing side, comprises: first polarizing film 11 / first adhesive layer 21 / touch sensor portion 5 / drive electrode / sensor portion 6 / first transparent substrate 41 / liquid crystal layer 3 / drive electrode 7 / second transparent substrate 42 / second adhesive layer 22 / second polarizing film 12. In the top-mounted in-cell touch sensing LCD panel shown in FIG8 , for example, liquid crystal cell C has the touch sensor portion 5 and drive electrode / sensor portion 6 on the outside of first transparent substrate 41. The touch sensor portion 5 is in direct contact with first adhesive layer 21. Furthermore, liquid crystal cell C has drive electrode 7 on the second transparent substrate 42 side within the first and second glass substrates 41 and 42 sandwiching the liquid crystal layer 3 (inside the liquid crystal cell).

[0137] In a liquid crystal panel with an embedded touch sensor function, when the touch sensor portion 5 of the liquid crystal cell C directly contacts the first adhesive layer 21, the antistatic properties of the first adhesive layer 21 (containing an ionic compound) are easily degraded, particularly in humid environments. Therefore, the liquid crystal panel with an embedded touch sensor function of the present invention is suitable for use in the aforementioned example of an embedded touch sensor type (variant) as shown in FIG. 7 or an embedded touch sensor type as shown in FIG. 8 .

[0138] Furthermore, the first polarizing film 11 disposed on the viewing side of the liquid crystal cell C and the second polarizing film 12 disposed on the opposite side of the viewing side can be layered with other optical films, depending on the suitability of their respective placements. Examples of these other optical films include reflective or transmissive plates, retardation films (including half-wavelength or quarter-wavelength plates), viewing angle compensation films, brightness enhancement films, and other optical layers used in liquid crystal displays. These films can be used in single or multiple layers. When using these other optical films, the adhesive layer closest to the liquid crystal layer 3 is preferably used as the first adhesive layer 21.

[0139] The liquid crystal layer 3 of the liquid crystal cell C can be a liquid crystal layer containing liquid crystal molecules aligned parallel to each other in the absence of an electric field, as used in liquid crystal panels with built-in touch sensing functionality. An IPS-type liquid crystal layer is suitable for use as the liquid crystal layer 3. Alternatively, any type of liquid crystal layer can be used, such as a TN-type, STN-type, π-type, or VA-type liquid crystal layer. The thickness of the liquid crystal layer is, for example, approximately 1.5 μm to 4 μm.

[0140] In the liquid crystal cell C, a first transparent substrate 41 and a second transparent substrate 42 can sandwich the aforementioned liquid crystal layer 3 to form the liquid crystal cell. A touch sensor portion 5, a drive electrode / sensor portion 6, drive electrodes 7, and the like can be formed inside or outside the liquid crystal cell, depending on the configuration of the liquid crystal panel with built-in touch sensing functionality. Furthermore, a color filter substrate can be provided on the liquid crystal cell (first transparent substrate 41).

[0141] The transparent substrate can be made of materials such as glass or polymer films. Examples of polymer films include polyethylene terephthalate, polycycloolefin, and polycarbonate. When the transparent substrate is made of glass, its thickness is, for example, approximately 0.3 mm to 1 mm. When the transparent substrate is made of a polymer film, its thickness is, for example, approximately 10 μm to 200 μm. The transparent substrate may have an adhesive layer or a hard coating layer on its surface.

[0142] The touch sensor portion 5 (capacitive sensor), the drive electrode / sensor portion 6, and the drive electrode 7 are formed as a transparent conductive layer. The material constituting the transparent conductive layer is not particularly limited, and examples thereof include metals such as gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, titanium, iron, cobalt, tin, magnesium, and tungsten, as well as alloys thereof. Furthermore, the material constituting the transparent conductive layer includes metal oxides of indium, tin, zinc, gallium, antimony, zirconium, and cadmium. Specifically, examples include metal oxides composed of indium oxide, tin oxide, titanium oxide, cadmium oxide, and mixtures thereof. Other metal compounds such as copper iodide can also be used. The metal oxides may further contain oxides of the metal atoms listed in the above groups, as needed. Preferred materials include indium oxide containing tin oxide (ITO) and tin oxide containing antimony, with ITO being particularly preferred. ITO preferably contains 80-99% by weight of indium oxide and 1-20% by weight of tin oxide.

[0143] There are no restrictions on where the touch sensor layer 5 is formed in the liquid crystal cell C; it can be formed to suit the form of the liquid crystal panel with built-in touch sensing functionality. For example, Figures 6 to 8 illustrate a case where the touch sensor layer 5 is disposed between the first polarizing film 11 and the liquid crystal layer 3. The touch sensor layer 5 can be formed, for example, on the first transparent substrate 41 as a transparent electrode pattern. Regarding the drive electrode / sensor portion 6 and the drive electrode 7, the transparent electrode pattern can be formed using conventional methods to suit the form of the liquid crystal panel with built-in touch sensing functionality. The transparent electrode pattern is typically electrically connected to a wiring (not shown) formed at the end of the transparent substrate, which in turn is connected to a controller IC (not shown). Besides comb-shaped, the transparent electrode pattern can adopt any other shape, such as stripes or diamonds, depending on the application. 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.

[0144] Furthermore, the LCD panel with built-in touch sensing function can be appropriately used as a component of the LCD device such as a backlight or a reflector used in a lighting system. Example

[0145] The present invention is further illustrated below using examples, but the present invention is not limited to these examples. In each example, all parts and percentages are by weight. Unless otherwise specified, the room temperature conditions are 23°C and 65% RH.

[0146] <Measurement of Weight Average Molecular Weight of (Meth)Acrylic Polymer (A)> The weight average molecular weight (Mw) of the (meth)acrylic polymer (A) was measured by GPC (gel permeation chromatography), and Mw / Mn was measured in the same manner. Analyzer: Tosoh Corporation, HLC-8120GPC Column: Made by Tosoh, G7000H XL+GMH XL+GMH XL Column size: 7.8mmφ×30cm each, totaling 90cm Column temperature: 40℃ Flow rate: 0.8mL / min Injection volume: 100μL ·Eluent: Tetrahydrofuran Detector: Differential Refractometer (RI) Standard sample: Polystyrene

[0147] <Production Example 1> (Production of 40μm TAC film with HC and 25μm TAC film with HC) To a resin solution (DIC Corporation, trade name: UNIDIC 17-806, solids concentration: 80%) containing a UV-curable resin monomer or oligomer primarily composed of urethane acrylate dissolved in butyl acetate, 5 parts of a photopolymerization initiator (BASF Corporation, trade name: IRGACURE 907) and 0.1 parts of a leveling agent (DIC Corporation, trade name: GRANDIC PC4100) were added per 100 parts of the solids content. Furthermore, cyclopentanone and propylene glycol monomethyl ether were added to the solution at a ratio of 45:55 to achieve a solids concentration of 36%, thereby preparing a hard coat layer material. This hard coat layer material was then applied to a TJ40UL (Fujifilm Corporation, raw material: triacetyl cellulose polymer, thickness: 40 μm) film so that the cured hard coat layer had a thickness of 7 μm. After that, the coating was dried at 90°C for 1 minute and irradiated with ultraviolet light at a cumulative light intensity of 300 mJ / cm2 using a high-pressure mercury lamp to harden the coating to form a hard coating (HC) and produce a 40 μm TAC film with HC. Then, a hard coating layer (HC) with a thickness of 7 μm was formed on TJ25UL (manufactured by Fuji Film, raw material: triacetyl cellulose polymer, thickness: 25 μm) in the same manner as above, thereby producing a 25 μm TAC film with HC.

[0148] <Production Example 2> (Making 30μm acrylic film) A 30 L autoclave reactor equipped with a stirrer, a temperature sensor, a cooling tube, and a nitrogen inlet was charged with 8,000 g of methyl methacrylate (MMA), 2,000 g of methyl 2-(hydroxymethyl)acrylate (MHMA), 10,000 g of 4-methyl-2-pentanone (methyl isobutyl ketone, MIBK), and 5 g of n-dodecyl mercaptan. The reaction mixture was heated to 105° C. and refluxed while nitrogen was passed through the reactor. Then, 5.0 g of tertiary butyl peroxyisopropyl carbonate (Kayakarubon BIC-7, manufactured by KAYAKU AKZO CO., LTD.) was added as a polymerization initiator. Simultaneously, a solution consisting of 10.0 g of tertiary butyl peroxyisopropyl carbonate and 230 g of MIBK was added dropwise over 4 hours. Solution polymerization was carried out at approximately 105-120° C. under reflux, followed by aging for an additional 4 hours. 30 g of a mixture of octadecyl phosphate and dioctadecyl phosphate (Phoslex A-18, manufactured by Sakai Chemical Industry Co., Ltd.) was added to the resulting polymer solution, and a cyclocondensation reaction was carried out under reflux at approximately 90-120°C for 5 hours. The resulting polymer solution was then introduced into a vented twin-screw extruder (φ = 29.75 mm, L / D = 30) at a processing rate of 2.0 kg / h, calculated as the resin weight, where the cyclocondensation reaction and devolatilization were further carried out, followed by extrusion. Transparent pellets of the lactone ring-containing polymer were produced. The vented twin-screw extruder had a barrel temperature of 260°C, a rotational speed of 100 rpm, a reduced pressure of 13.3-400 hPa (10-300 mmHg), one rear vent hole, and four front vent holes. Dynamic TG analysis of the resulting lactone ring-containing polymer revealed a mass loss of 0.17% by mass. Furthermore, the lactone ring-containing polymer had a weight-average molecular weight of 133,000, a melt flow rate of 6.5 g / 10 min, and a glass transition temperature of 131°C. The pellets 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 mm φ) to obtain transparent pellets. The glass transition temperature of the pellets was 127°C. The pellets were melt-extruded through a 400mm wide coat-hanger T-die using a 50mm diameter uniaxial extruder to produce a 120μm thick film. The resulting film was then stretched to 2.0 times its original length in the longitudinal direction and 2.0 times its original length in the transverse direction at 150°C using a biaxial stretching device, resulting in a 30μm thick stretched film (30μm acrylic film). Optical properties of the stretched film were measured, revealing a total light transmittance of 93%, an in-plane retardation Δnd of 0.8nm, and a thickness-direction retardation Rth of 1.5nm.

[0149] <Making polarizing film(1)> A polyvinyl alcohol film of 45 μm in thickness was dyed in a 0.3% iodine solution at 30°C for 1 minute between rollers of different speed ratios and stretched to 3 times. Thereafter, the film was immersed in an aqueous solution containing 4% boric acid and 10% potassium iodide at 60°C for 0.5 minutes while being stretched to a total stretching ratio of 6 times. Subsequently, the film was immersed in an aqueous solution containing 1.5% potassium iodide at 30°C for 10 seconds to be cleaned, and then dried at 50°C for 4 minutes to obtain a polarizer of 18 μm in thickness. A 40 μm TAC film (triacetyl cellulose film side) with HC obtained in Example 1 and subjected to saponification was bonded to one side of the polarizer using a polyvinyl alcohol adhesive, and a 30 μm acrylic film obtained in Example 2 was bonded to the other side to produce a polarizing film (1).

[0150] <Making polarizing film (2)> (Making a thin polarizer A) A single surface of an amorphous isophthalic acid-co-polyethylene terephthalate (IPA-co-PET) film substrate (thickness: 100 μm) with a water absorption of 0.75% and a Tg of 75°C was corona treated. An aqueous solution containing polyvinyl alcohol (DP 4200, saponification degree 99.2 mol%) and acetyl-modified PVA (DP 1200, acetyl-modification degree 4.6%, saponification degree 99.0 mol% or greater, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name "Gohsefimer Z200") in a 9:1 ratio was applied to the corona-treated surface and dried to form an 11 μm thick PVA resin layer. This produced a laminate. The obtained laminate was subjected to free-end uniaxial stretching by 2.0 times in the longitudinal direction (long side direction) between rollers of different peripheral speeds in an oven at 120°C (in-air auxiliary stretching treatment). Next, the laminate was immersed in an insolubilization bath (a boric acid aqueous solution prepared 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 (insolubilization treatment). Next, the polarizing plate was immersed in a dye bath at a temperature of 30°C while adjusting the iodine concentration and immersion time to achieve a predetermined transmittance. In this example, the polarizing plate was immersed in an iodine aqueous solution prepared 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, the film was immersed in a cross-linking bath (a boric acid aqueous solution prepared 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 (cross-linking treatment). Thereafter, the laminate was immersed in an aqueous boric acid solution at a liquid temperature of 70°C (an aqueous solution obtained by mixing 4 parts by weight of boric acid and 5 parts by weight of potassium iodide with respect to 100 parts by weight of water) and uniaxially stretched in the longitudinal direction (long side direction) between rollers of different peripheral speeds so that the total stretching ratio reached 5.5 times (in-water stretching). Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution prepared 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 film laminate including a polarizer having a thickness of 5 μm was obtained.

[0151] (Making adhesive for transparent protective film) A UV-curable adhesive was prepared by mixing 45 parts by weight of acryloylmorpholine, 45 parts of 1,9-nonanediol diacrylate, 10 parts of an acrylic oligomer obtained by polymerizing a (meth)acrylic acid monomer (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.).

[0152] <Making polarizing film (2)> On the surface of the polarizer A of the optical film laminate, the UV curable adhesive is applied so that the thickness of the cured adhesive layer becomes 1 μm, and the 25 μm TAC film with HC obtained in the above-mentioned manufacturing example 1 (on the triacetyl cellulose film side) is attached, and then irradiated with ultraviolet light as active energy rays to cure the adhesive. The ultraviolet irradiation is performed using a gallium-filled metal halide lamp, the irradiation device: Light HAMMER10 manufactured by Fusion UV Systems, Inc., the bulb: V bulb, the peak illuminance: 1600 mW / cm2, the cumulative irradiation dose 1000 / mJ / cm2 (wavelength 380~440 nm), and the ultraviolet irradiance is measured using the Sola-Check system manufactured by Solatell. Then, the amorphous PET substrate is peeled off to produce a polarizing film (2) using a thin polarizer. The optical properties of the obtained polarizing film are a single-unit transmittance of 42.8% and a polarization degree of 99.99%.

[0153] <Production of polarizing film with transparent layer (2)> The transparent layer forming material described below is applied to the polarizing element surface of the polarizing film (2) (the surface of the polarizing element not provided with the 25 μm TAC film with HC) by a rod coater, and then heat treated at 60° C. for 12 hours to form a urethane resin layer with a thickness of 3 μm, thereby producing a polarizing film (2) with a transparent layer.

[0154] Transparent layer forming materials As the solution of the urethane prepolymer (a), a 75% ethyl acetate solution of a urethane prepolymer composed of toluene diisocyanate (TDI) and trimethylolpropane (TMP) (manufactured by Tosoh Corporation, trade name "CORONATE L") was used. On the other hand, trimethylolpropane was dissolved in cyclopentanone so as to have a solid content concentration of 10% to prepare a trimethylolpropane solution. The trimethylolpropane solution was added to 100 parts of a 75% ethyl acetate solution of the urethane prepolymer (manufactured by Tosoh Corporation, trade name "Coronate L") to adjust the solid content ratio of urethane prepolymer to trimethylolpropane to 90:10. 0.1 part of a dioctyltin dilaurate catalyst (manufactured by Tokyo Fine Chemical Co., Ltd., trade name "EMBILIZER OL-1") was then added, and methyl isobutyl ketone was added as a solvent to prepare a forming material (coating solution) having a solid content concentration of 10%.

[0155] 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 part 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. Furthermore, 0.1 parts of 2,2'-azobisisobutyronitrile (a polymerization initiator) and 100 parts of ethyl acetate were added to 100 parts of the monomer mixture (solid content). After nitrogen substitution with gentle stirring, the liquid temperature in the flask was maintained at approximately 55°C and a polymerization reaction was conducted for 8 hours to prepare a solution of an acrylic polymer with a weight-average molecular weight (Mw) of 2.2 million and an Mw / Mn ratio of 4.0.

[0156] (Preparation of adhesive composition) To 100 parts of the solid content of the acrylic polymer solution obtained above were added 10 parts of lithium bis(trifluoromethanesulfonyl)imide, 0.6 parts of an isocyanate crosslinker (Coronate L, trimethylolpropane diisocyanate toluene, manufactured by Tosoh Corporation), 0.1 parts of benzoyl peroxide (NYPER BMT, manufactured by NOF Corporation), and 0.3 parts of an epoxy-containing silane coupling agent (X-41-1056, manufactured by Shin-Etsu Chemical Co., Ltd.) to prepare an acrylic adhesive solution.

[0157] (Making polarizing film with adhesive layer) Next, the solution of the acrylic adhesive composition was applied to one side of a polyethylene terephthalate film (separator 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 separator film. Next, the adhesive layer formed on the separator film was transferred to the acrylic film side of the polarizing film (1) prepared above, thereby producing a polarizing film with an adhesive layer.

[0158] Examples 2-10, Comparative Examples 1-2 In Example 1, the types of monomers used to prepare the acrylic polymer (A) and their usage ratios were changed as shown in Table 1, and the production conditions were controlled to prepare a solution of the acrylic polymer (A) described in Table 1.

[0159] 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, was changed to that shown in Table 1. A polarizing film with an adhesive layer was prepared in the same manner as in Example 1 except that the type of polarizing film, the type of ionic compound (B) used to prepare the adhesive composition, or the blending ratio thereof, was changed to that shown in Table 1. Furthermore, when the aforementioned polarizing film (2) was used as the polarizing film, the adhesive layer described in Table 1 was formed on the polarizer surface of the aforementioned polarizing film (2) (the surface of the polarizer not provided with the 25 μm TAC film with HC attached) in the same manner as described above. When the aforementioned polarizing film (2) with a transparent layer was used as the polarizing film, the adhesive layer described in Table 1 was formed on the transparent layer of the aforementioned polarizing film (2) with a transparent layer in the same manner as described above.

[0160] The polarizing films with adhesive layers obtained in the above examples, comparative examples, and reference examples were evaluated as follows. The evaluation results are listed in Table 1.

[0161] <Surface resistance (Ω / □): Conductivity> After peeling off and separating the polarizing film from the adhesive layer, the surface resistance value of the surface of the adhesive layer was measured as the surface resistance value of the polarizing film of the adhesive layer. The measurement was carried out using MCP-HT450 manufactured by Mitsubishi Chemical ANALYTECH Co., Ltd.

[0162] <Measurement of creep value> The upper end portion of 10 mm × 10 mm of the polarizing film of the adhesive layer (thickness of the adhesive layer: 20 μm) cut into a size of 10 mm × 30 mm was attached to the SUS plate through the adhesive layer, and autoclave treatment was carried out for 15 minutes under the conditions of 50 °C and 5 atmospheres. A precision heating plate with the heating surface set vertically was heated to 85 °C, and the SUS plate with the polarizing film of the adhesive layer attached was set such that the surface without the adhesive layer was in contact with the heating surface of the heating plate. After starting to heat the SUS plate at 85 °C for 5 minutes, a load of 500 g was applied to the lower end portion of the polarizing film of the adhesive layer and left for 1 hour, and then the offset amplitude between the polarizing film of the adhesive layer and the SUS plate before and after applying the load was measured, and this offset amplitude was used as the creep value (μm) at 85 °C.

[0163] <Durability test> The absorption axis of the polarizing film of the produced polarizing film of the adhesive layer was made parallel to the long side and cut into a size of 300 × 220 mm. The polarizing film of the adhesive layer was laminated to an alkali-free glass (product name "EG-XG" manufactured by Corning Co., Ltd.) with a thickness of 350 × 250 mm × 0.7 mm using a laminator. Then, autoclave treatment was carried out at 50 °C and 0.5 MPa for 15 minutes to make the adhesive layer adhere closely to the glass. After subjecting the specimen subjected to the above treatment to treatment for 500 hours in a gas environment at 85 °C and treatment for 500 hours in a gas environment at 60 °C / 95% RH, the appearance of the specimen was evaluated visually according to the following criteria. (Evaluation criteria) A: There are no appearance changes such as foaming and peeling at all. B: Although there is very little peeling or foaming at the end, it is practically no problem. C: There is peeling or foaming at the end, but it is practically no problem as long as it is not for a special purpose. D: There is significant peeling at the end, which is a problem in practical use.

[0164] <ESD test> After removing the separator film from the polarizing film with an adhesive layer, the film was bonded to the viewing side of an embedded liquid crystal cell (LCD cell) to create a LCD panel with built-in touch sensing functionality. Specifically, the resulting polarizing film with an adhesive layer was bonded to the first transparent substrate of the embedded LCD cell (Figure 6), forming the first adhesive layer and the first polarizing film. The polarizing film of the LCD panel was tested with a surface-emission ESD (electrostatic discharge) gun (10 kV) to measure the time it took for the whitened portion, caused by electrical discharge, to disappear, and the evaluation was based on the following criteria. (Evaluation Criteria) A: Within 1 second. B: More than 1 second and less than 10 seconds. C: More than 10 seconds.

[0165] <Evaluation of Alien Cracks> The polarizing film with the 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 400 ppi. The profiled polarizing film with an adhesive layer was laminated to 350 mm × 250 mm × 0.7 mm thick alkali-free glass (Corning, trade name "EG-XG"). The film was then autoclaved at 50°C and 0.5 MPa for 15 minutes to ensure adhesion of the adhesive layer to the glass. The treated samples were placed in a thermal cycle test chamber and visually inspected for cracks in the profiled area at 100 and 200 cycles. Five identical samples were placed under each condition, and the number of cracked samples is recorded in Table 1. (Test conditions) Temperature conditions: -40°C (hold for 30 minutes) → 85°C (hold for 30 minutes) as one cycle, and heating and cooling rate: 10°C / min

[0166] <Evaluating End Fading> The single-sided (or double-sided) polarizing films with adhesive layers obtained in the Examples and Comparative Examples were cut into 50 mm x 50 mm pieces. After removing the separator film, the films were bonded to 1.2-1.5 mm thick alkali glass (Slide Glass, manufactured by Matsunami Glass Co., Ltd.) through the adhesive layer to prepare samples. After maintaining the samples in a high-temperature, high-humidity environment at 60°C and 90% RH for 500 hours, the edge discoloration was measured using a differential interference microscope (Olympus, product name "MX-61L") under the following conditions. The edge discoloration was determined by measuring the distance (μm) between the corner and the point closest to the center of the sample where the color becomes lighter than the center. The average value of the four corners was used as the edge discoloration for the sample. Device: Olympus MX-61L Measurement conditions Lens magnification: 5 times ISO:200 Shutter speed: 1 / 100 Reflected light: scale 0 White balance: Automatic Transmitted light controller:LG-PS2 Transmitted light: 5 scales Polarization direction of transmitted light: Orthogonal polarization direction to the transmission axis of polarizing film

[0167] [Table 1]

[0168] In Table 1: BA represents butyl acrylate, PEA: Phenoxyethyl acrylate, AA represents acrylic acid, NVP stands for N-vinyl-2-pyrrolidone, HBA: 4-hydroxybutyl acrylate, Isocyanate refers to an isocyanate crosslinking agent (CORONATE L manufactured by Tosoh Corporation, trimethylolpropane diisocyanate toluene), BPO stands for benzoyl oxide (NYPER BMT manufactured by NOF Corporation), Li-TFSI represents lithium bis(trifluoromethanesulfonyl)imide, Potassium K-bis(trifluoromethanesulfonyl)imide TMPA-TFSI represents trimethylpropylammonium bis(trifluorosulfonyl imide), EMP-TFSI represents ethylmethylpyrrolidinium bis(trifluorosulfonyl imide), TBMA-TFSI represents tributylmethylammonium bis(fluorosulfonyl imide), MTOA-TFSI stands for methyltrioctylammonium bis(trifluorosulfonylimide).

[0169] 1: Polarizing film with adhesive layer 2: Notch (special-shaped part) 3: Liquid crystal layer 4: The intersection of two straight lines 5: Touch sensor part 6: Driving electrode and sensor part 7: Driving electrode 11: Single-sided protective polarizing film 11A: Single-sided protective polarizing film 12:Second polarizing film 21: (1st) Adhesive layer 22: Second adhesive layer 41: 1st transparent substrate 42: Second transparent substrate A2: Single-sided protective polarizing film C: Liquid crystal unit D: Maximum depth of the notch starting from W1 R1: Radius of curvature of the curve W1: length of the notch a: Polarizer b: Protective film c: transparent layer θ1: Angle formed by two straight lines

Claims

1. A polarizing film with an adhesive layer, comprising a polarizing film and an adhesive layer, the polarizing film having a polarizing element and a protective film located on one or both sides of the polarizing element; characterized in that: the polarizing film with the adhesive layer has irregularly shaped portions other than rectangular; the adhesive layer is formed from an adhesive composition containing a (meth)acrylic polymer (A) and an ionic compound (B) with a molecular weight of 210 or less containing a cationic component; the (meth)acrylic polymer (A) has alkyl (meth)acrylic acid esters and functionalized monomers selected from carboxyl-containing monomers, hydroxyl-containing monomers and amide-containing monomers as monomer units; the creep value of the adhesive layer at 85°C is 120 μm or less.

2. The polarizing film of the adhesive layer as claimed in claim 1, wherein the aforementioned cationic component is lithium ion.

3. The polarizing film of the adhesive layer of 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).

4. The polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the aforementioned protective film is selected from either cellulose resin film or (meth)acrylic resin film.

5. A polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the thickness of the aforementioned polarizing element is 10 μm or less.

6. A polarizing film with an adhesive layer as claimed in claim 1 or 2, wherein the aforementioned polarizing film is a single-sided protective polarizing film having a polarizing element and a protective film on only one side of the aforementioned polarizing element.

7. The polarizing film with an adhesive layer as claimed in claim 6, wherein the aforementioned single-sided protective polarizing film has the aforementioned adhesive layer on the other side of the aforementioned polarizing element.

8. The polarizing film with an adhesive layer as claimed in claim 7, wherein the adhesive layer is present on the other side of the aforementioned polarizing element in the aforementioned single-sided protective polarizing film, with a transparent layer in between, the transparent layer being formed directly on the aforementioned polarizing element and having a thickness of 10 μm or less.

9. The polarizing film with an adhesive layer as claimed in claim 8, wherein the aforementioned transparent layer is a hardened form containing a carbamate prepolymer, and the carbamate prepolymer is a reaction product of an isocyanate compound and a polyol.

10. An image display panel, characterized in that: a polarizing film having an adhesive layer as claimed in any one of claims 1 to 9.

11. The image display panel of claim 10, wherein the liquid crystal cell having a liquid crystal layer and a touch sensor portion with embedded touch sensing function is bonded with the aforementioned adhesive layer of a polarizing film.

12. An image display device, characterized in that it has an image display panel as claimed in claim 10 or 11.

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