TWI891646B - Polarizing plate with pressure-sensitive adhesive layer - Google Patents

Abstract

An objective of this invention is to provide a polarizing plate with pressure-sensitive adhesive layer including a pressure-sensitive adhesive layer containing an antistatic agent, which is hardly peeled off even when subjected to a physical shock.

A polarizing plate with pressure-sensitive adhesive layer of this invention contains a polarizing plate, and a pressure-sensitive adhesive layer laminated and in contact with the polarizing plate, which has four sides and four corners, wherein at least one corner is a rounded corner having a radius of curvature of 1.0 mm or more, and the pressure-sensitive adhesive layer contains an antistatic agent. If the resistance values of the surface of the pressure-sensitive adhesive layer on the side opposite to the polarizing plate side before and after being held at a temperature of 85°C for 100 hours are set to be R1 [Ω/□] and R2 [Ω/□], respectively, the change rate △R [%] calculated by formula (3) satisfies the relationship of formula (1).

△R=[(R2-R1)/R1]×100 (3)

△R≧25 (1)

Description

Polarizing plate with adhesive layer

The present invention relates to a polarizing plate with an adhesive layer, comprising a polarizing plate and an adhesive (pressure-sensitive adhesive) layer, and an image display device.

Polarizing plates, made by laminating a protective film on one or both sides of a polarizer, are widely used in image display devices such as liquid crystal displays (LCDs) and organic electroluminescent (EL) displays, primarily mobile TVs. In recent years, they have become increasingly popular as optical components in various mobile devices, including cell phones, smartphones, and tablet computers.

Polarizing plates are often used by attaching them to image display devices (such as liquid crystal cells and organic EL displays) via an adhesive layer [see, for example, Japanese Patent Application Publication No. 2010-229321 (Patent Document 1)]. Therefore, some polarizing plates are commercially available in the form of adhesive-coated polarizing plates, where an adhesive layer is pre-applied on one side.

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Application Laid-Open No. 2010-229321

Polarizing plates with adhesive layers can improve their antistatic performance by including an antistatic agent in the adhesive layer. However, when the adhesive layer contains an antistatic agent, the adhesive strength is reduced, making it more susceptible to peeling due to physical impact. From a design perspective, when the polarizing plate is attached to the edge of the panel, physical impact is more likely to be transmitted to the adhesive layer, making the peeling problem more significant.

The present invention provides a polarizing plate with an adhesive layer, which has an adhesive layer containing an antistatic agent and is not easily peeled off even when subjected to physical impact, and an image display device including the polarizing plate with the adhesive layer.

The present invention provides a polarizing plate and an image display device with an adhesive layer as shown below.

[1] A polarizing plate with an adhesive layer, comprising a polarizing plate and an adhesive layer bonded to and laminated on the polarizing plate.

The polarizing plate with the adhesive layer has four sides and four corners, wherein:

At least one of the four aforementioned corners must be a rounded corner with a radius of curvature of 1.0 mm or greater.

The aforementioned adhesive layer contains an antistatic agent.

When the resistance values of the surface of the adhesive layer opposite to the polarizer side after being stored at 85°C for about 100 hours are set to R1[Ω/□] and R2[Ω/□] respectively, the change rate △R[%] calculated by formula (3) satisfies the relationship of formula (1).

△R=〔(R2-R1)/R1〕×100 (3)

△R≧25 (1)

[2] The polarizing plate with an adhesive layer as described in [1] has a rectangular shape.

[3] A polarizing plate with an adhesive layer as described in [1] or [2], wherein the polarizing plate comprises a polarizer layer and a first protective film,

The aforementioned first protection is a polar resin film.

The first protective film is in contact with the adhesive layer.

[4] A polarizing plate with an adhesive layer as described in [1] or [2], wherein the polarizing plate comprises a polarizer layer and a curable resin composition curing layer,

The hardened layer of the curable resin composition is in contact with the adhesive layer.

[5] An image display device comprising an image display element and a polarizing plate with an adhesive layer as described in any one of [1] to [4], wherein the adhesive layer of the polarizing plate with an adhesive layer is in contact with and laminated on the image display element.

[6] The image display device as described in [5], wherein the outer shape of the polarizing plate with the adhesive layer is located within the outer shape of the image display element.

In the outer shape of the polarizing plate with the adhesive layer, the outer portion that is less than 1.0 mm away from the outer shape of the image display element is longer than the outer portion that exceeds 1.0 mm.

[7] An image display device comprising an image display element and a polarizing plate with an adhesive layer as described in [1] or [2], wherein the adhesive layer of the polarizing plate with an adhesive layer is in contact with and laminated to the image display element.

[8] The image display device as described in [7], wherein the outer shape of the polarizing plate with the adhesive layer is located within the outer shape of the image display element.

The distance between the rounded corner portion of the outer shape of the polarizing plate with the adhesive layer and the outer shape of the image display device is less than 1.0 mm.

According to the present invention, a polarizing plate with an adhesive layer that is not easily peeled off even when subjected to physical impact can be provided.

1:Polarizer

2: Surface treatment layer

3: Second protective film

4: First protective film

5: Hardening layer of hardening resin composition

10:Polarizing plate

20: Adhesive layer

25: Polarizing plate with adhesive layer

26: Polarizing plate with adhesive layer

27: Polarizing plate with adhesive layer

28: Appearance

28a: Edge

28b: Edge (shape)

28c: Edge

28d: Edge

30: Image display component

31: Appearance

31b: Appearance

A: Partial

C: Section

d: distance

dc: distance

Figure 1 is a schematic cross-sectional view showing an example of a polarizing plate with an adhesive layer and an image display device according to the present invention.

Figure 2 is a schematic cross-sectional view showing another example of a polarizing plate with an adhesive layer and an image display device according to the present invention.

Figure 3 is a schematic cross-sectional view showing another example of a polarizing plate with an adhesive layer and an image display device according to the present invention.

Figure 4 is a top view showing an example of the outer shape of a polarizing plate with an adhesive layer according to the present invention.

Figure 5 shows an example of the relationship between the outer shape of a polarizing plate with an adhesive layer and the outer shape of an image display device. (a) is a top view showing the relationship with rounded corners, and (b) is a top view showing the relationship with right-angled corners.

Figure 6 is a top view showing an example of the outer shape of a polarizing plate with a rectangular adhesive layer.

<Polarizing plate with adhesive layer>

[1] Composition of polarizing plate with adhesive layer

A polarizing plate with an adhesive layer includes a polarizing plate and an adhesive layer laminated on the polarizing plate. The adhesive layer contains an antistatic agent. When the polarizing plate with an adhesive layer is stored at a temperature of 85°C for about 100 hours, and the resistance values of the surface of the adhesive layer opposite to the polarizing plate are set to R1 [Ω/□] and R2 [Ω/□] respectively, the change rate △R [%] calculated by formula (3) satisfies the relationship of formula (1) and also satisfies the relationship of formula (1').

△R=〔(R2-R1)/R1〕×100 (3)

△R≧25 (1)

△R≧50 (1’).

Figures 1 to 3 illustrate examples of the layered structure of a polarizing plate with an adhesive layer. The polarizing plate 25 with an adhesive layer shown in Figure 1 includes a polarizing plate 10 and an adhesive layer 20 laminated in contact with the polarizing plate 10. The polarizing plate 10 comprises a polarizer 1, a first protective film 4 adhered to the surface of the polarizer 1 facing the adhesive layer 20, and a second protective film 3 adhered to the surface of the polarizer 1 opposite the adhesive layer 20. As shown in Figure 1, the second protective film 3 may have a surface treatment layer 2 formed on its outer surface (the surface opposite the polarizer 1). The adhesive layer 20 is laminated in contact with the first protective film 4. The first protective film 4 is preferably a polar resin film. By making the first protective film 4 in contact with the adhesive layer 20 a polar resin film, a polarizing plate with an adhesive layer that satisfies the relationship of formula (1) can be easily constructed. The adhesive layer 20 can be used, for example, for bonding with the image display element 30.

The polarizing plate 26 with an adhesive layer shown in FIG2 is the same as that shown in FIG1 except that the first protective film 4 of the polarizing plate 25 with an adhesive layer shown in FIG1 is replaced by a curable resin composition curable layer 5. The adhesive layer 20 is in contact with and laminated on the curable resin composition curable layer 5. By contacting the curable resin composition curable layer 5 with the adhesive layer 20, a polarizing plate with an adhesive layer that satisfies the relationship of formula (1) can be easily constructed.

The polarizing plate 27 with an adhesive layer shown in FIG3 is the same as that shown in FIG1 except that it has a curable resin composition curing layer 5 formed on the outer surface (the surface opposite to the polarizer 1) of the first protective film 4 of the polarizing plate 25 with an adhesive layer shown in FIG1. The adhesive layer 20 is in contact with and laminated on the curable resin composition curing layer 5. By contacting the curable resin composition curing layer 5 with the adhesive layer 20, a polarizing plate with an adhesive layer that satisfies the relationship of formula (1) can be easily constructed.

In order to protect the exposed surface of the adhesive layer 20, the polarizing plates 25, 26, and 27 with the adhesive layer may have a spacer layer laminated on the outside of the adhesive layer 20 that can be peeled off from the adhesive layer.

Polarizing plates 25, 26, and 27 with adhesive layers are preferably rectangular or substantially rectangular sheets. When in sheet form, the dimensions are preferably 100 mm x 40 mm or larger, more preferably 150 mm x 40 mm or larger. The dimensions of the sheet are, for example, 1650 mm x 930 mm or smaller, preferably 1430 mm x 810 mm or smaller.

Figure 4 shows an example of a preferred outer shape of polarizing plates 25, 26, and 27 with an adhesive layer. The outer shape 28 of the polarizing plate with an adhesive layer shown in Figure 4 has four sides 28a, 28b, 28c, and 28d and four corners. The polarizing plate with an adhesive layer has a rectangular shape. The four sides are formed by two short sides 28a and 28c and two long sides 28b and 28d. The four corners are portions C formed by the connection between two adjacent sides. All of the four corners in the outer shape 28 of the polarizing plate with an adhesive layer are rounded. In other words, the four corners are chamfered and have an arc-like shape when viewed from above. This rounded shape offers excellent design.

In the outer shape 28 of the polarizing plate with an adhesive layer, the portion of the side other than portion C formed by the connection of two sides is referred to as portion A. The outer shape of the polarizing plate with an adhesive layer is not limited to the shape shown in Figure 4, but preferably has four corners, at least one of which has a rounded radius of curvature of 1.0 mm or greater.

Figure 5(a) shows an example of the relationship between the outer shape 28 of the polarizing plate with an adhesive layer and the outer shape 31 of the image display element 30 in an image display device. In Figure 5(a), to facilitate bonding, the outer shape 28 of the polarizing plate with an adhesive layer is slightly smaller than the outer shape 31 of the image display element, and is located within the outer shape 31 of the image display element. Furthermore, to ensure a good appearance, the distance d between the outer shape 28 of the polarizing plate with an adhesive layer and the outer shape 31 of the image display element is preferably 1.0 mm or less. Preferably, the distance d around the entire perimeter of the outer shape 28 of the polarizing plate with the adhesive layer is 1.0 mm or less. Alternatively, the deviation in the distance d around the entire perimeter of the outer shape 28 of the polarizing plate with the adhesive layer is small, preferably with the difference between the maximum and minimum values within 0.2 mm, but the present invention is not limited thereto. Preferably, within the outer shape 28, the outer shape portion with a distance d of 1.0 mm or less is longer than the outer shape portion with a distance d exceeding 1.0 mm. As shown in Figure 5(a), when all corners of portion C in the outer shape 28 of the polarizing plate with an adhesive layer are rounded, and all four corners of the outer shape 31 of the image display element are also rounded, this is preferred because the distance dc of portion C can be made the same as the distance d of portion A, which constitutes the other portions. This reduces the variation in distance d around the outer shape 28 of the polarizing plate with an adhesive layer. To improve design, the distance dc of portion C is preferably 1.0 mm or less.

Figure 5(b) illustrates a different external shape relationship from that shown in Figure 5(a), with the corners of the polarizing plate with an adhesive layer and the image display device's outer shape at right angles. As shown in Figure 5(b), when all corners of portion C in the outer shape 28b of the polarizing plate with an adhesive layer are right angles, and all corners of the outer shape 31b of the image display device are also right angles, and when the distance dc in portion A is d, the distance of the corners of portion C is generally approximately √2×d.

Portable image display devices such as smartphones are more likely to be subjected to physical shocks due to being dropped. The four corners of an image display device are more susceptible to physical shocks than other parts because they are protruding. As shown in Figure 5(a), in a configuration where the corners are rounded and the distance dc from the outer shape 31 of the image display element is as short as that of other parts, the physical shocks received by the corners are transmitted to the adhesive layer without attenuation, making it easy for the corners to peel off. On the other hand, as shown in Figure 5(b), in a configuration where the four corners are right angles and the distance dc from the outer shape 31b of the image display element is longer than that of other parts, the physical shocks received by the corners are easily attenuated, so peeling is easily suppressed. When the adhesive layer 20 contains an antistatic agent, the problem of peeling becomes more significant due to the low adhesion between the adhesive layer 20 and the polarizing plate. According to the present invention, even when the polarizing plate with the adhesive layer has rounded corners, it still has excellent impact resistance.

The polarizing plate with an adhesive layer of the present invention can suppress peeling due to physical impact by satisfying the relationship of formula (1) even when the adhesive layer 20 contains an antistatic agent. It is preferable that the adhesive layer 20, when the surface resistance values of the side opposite to the polarizing plate side of the adhesive layer are set to R1 [Ω/□] and R2 [Ω/□] respectively after being stored at a temperature of 85°C for about 100 hours, the change rate ΔR [%] calculated by formula (3) satisfies the relationship of formula (2).

△R=〔(R2-R1)/R1〕×100 (3)

△R≦98 (2)

The reason why △R satisfies formula (1) and becomes less likely to peel off even when subjected to physical impact is generally considered to be as follows. The adhesive layer adheres to the image display element through the adhesive force exerted by the adhesive exposed on its surface. The adhesive layer contains an antistatic agent. When the antistatic agent is present on the surface in large quantities, the amount of antistatic agent exposed on the surface increases relatively, and the proportion of adhesive decreases relatively. Since the antistatic agent does not contribute to adhesion, the adhesion force with the image display element decreases, making it easier for the polarizing plate to peel off due to physical impact.

On the other hand, formula (1) shows how easily the antistatic agent migrates from the surface of the adhesive layer. That is, a ΔR of 25 or greater (formula (1)) indicates that the antistatic agent easily migrates into the adhesive layer, meaning that the amount of antistatic agent exposed on the surface tends to decrease. When the amount of antistatic agent exposed on the surface decreases, the amount of adhesive exposed increases relatively, resulting in greater adhesion of the image display device.

More specifically, it is believed that △R can be considered as a value that indirectly indicates the proportion of antistatic agent present on the surface of the adhesive layer that migrates into the adhesive layer after storage at 85°C for 100 hours.

[2]Polarizing plate

The polarizing plate 10 constituting the polarizing plates 25, 26, and 27 with the adhesive layer includes at least a polarizer 1, typically a thermoplastic resin film laminated on at least one side thereof as a protective film.

[2-1]Polarizer

The polarizer 1 is a film that selectively transmits linearly polarized light from natural light in a certain direction. Examples include iodine-based polarizers in which iodine, a dichroic pigment, is adsorbed and aligned on a polyvinyl alcohol resin film; dye-based polarizers in which a dichroic dye is adsorbed and aligned on a polyvinyl alcohol resin film; and coated polarizers in which a dichroic dye in the form of a lyotropic liquid crystal is applied, aligned, and fixed. Because these polarizers selectively transmit linearly polarized light from natural light in a certain direction and absorb linearly polarized light in the other direction, they are called absorption-type polarizers.

The polarizer 1 is not limited to an absorptive polarizer. It may also be a reflective polarizer that selectively transmits linearly polarized light from natural light in one direction and reflects linearly polarized light in another direction, or a scattering polarizer that scatters linearly polarized light in another direction. However, from the perspective of excellent visual recognition, an absorptive polarizer is preferred. Among them, a polyvinyl alcohol-based polarizer composed of a polyvinyl alcohol-based resin is more preferred. A polyvinyl alcohol-based polarizer in which a dichroic pigment such as iodine or a dichroic dye is adsorbed and aligned on the polyvinyl alcohol-based resin film is even more preferred. A polyvinyl alcohol-based polarizer in which iodine is adsorbed and aligned on the polyvinyl alcohol-based resin film is particularly preferred.

The polyvinyl alcohol resin used to form the polyvinyl alcohol polarizer can be a saponified polyvinyl acetate resin. In addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, polyvinyl acetate resins also include copolymers with other monomers that can be copolymerized with vinyl acetate. Examples of other monomers that can be copolymerized with vinyl acetate include unsaturated carboxylic acids, alkenes, vinyl ethers, unsaturated sulfonic acids, and (meth)acrylic amides containing ammonium salt groups.

The saponification degree of polyvinyl alcohol resins is typically 85 mol% to 100 mol%, preferably 98 mol% or higher. Polyvinyl alcohol resins may be modified; for example, aldehyde-modified polyvinyl formaldehyde or polyvinyl acetal can be used. The average degree of polymerization of polyvinyl alcohol resins is typically 1,000 to 10,000, preferably 1,500 to 5,000. The average degree of polymerization of polyvinyl alcohol resins can be determined in accordance with JIS K 6726.

The polyvinyl alcohol resin formed into a film can be used as the raw material film for the polarizer 1. The method for forming the polyvinyl alcohol resin into a film is not particularly limited, and a known method can be employed. The thickness of the polyvinyl alcohol raw material film is, for example, 150 μm or less, preferably 100 μm or less (e.g., 50 μm or less), and 5 μm or more.

The polarizer 1 can be manufactured by a method comprising the following steps: uniaxially stretching a polyvinyl alcohol-based resin film; dyeing the polyvinyl alcohol-based resin film with a dichroic dye to adsorb the dichroic dye; treating the polyvinyl alcohol-based resin film adsorbed with the dichroic dye with an aqueous boric acid solution (crosslinking treatment); and, washing the film with water after the boric acid solution treatment.

The uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before, simultaneously with, or after dyeing with the dichroic dye. When uniaxial stretching is performed after dyeing, it can be performed before or during the boric acid treatment. Furthermore, uniaxial stretching can be performed in multiple stages.

Uniaxial stretching can be performed between rollers with different circumferential speeds, or using heated rollers. Furthermore, uniaxial stretching can be performed dry in the atmosphere or wet using a solvent such as water while the polyvinyl alcohol-based resin film is swollen. The stretching ratio is typically between 3x and 8x.

Methods for dyeing a polyvinyl alcohol-based resin film with a dichroic dye include, for example, immersing the film in an aqueous solution containing the dichroic dye. Iodine or a dichroic organic dye is used as the dichroic dye. Furthermore, the polyvinyl alcohol-based resin film is preferably immersed in water before dyeing.

Iodine-based dyeing methods include immersing the polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide. The iodine content in the aqueous solution can be from 0.01 to 1 part by mass per 100 parts by mass of water. The potassium iodide content can be from 0.5 to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution can be from 20°C to 40°C.

Alternatively, dyeing with a dichroic organic dye involves immersing a polyvinyl alcohol-based resin film in an aqueous solution containing the dichroic organic dye. The aqueous solution containing the dichroic organic dye may contain an inorganic salt such as sodium sulfate as a dyeing auxiliary. The dichroic organic dye content in the aqueous solution may be between 1× ^10⁻⁴ parts by mass and 10 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution may be between 20°C and 80°C.

Boric acid treatment after dyeing with a dichroic dye can include immersing the dyed polyvinyl alcohol-based resin film in an aqueous solution containing boric acid. When iodine is used as the dichroic dye, the aqueous solution containing boric acid preferably contains potassium iodide. The amount of boric acid in the aqueous solution containing boric acid can be from 2 parts by mass to 15 parts by mass per 100 parts by mass of water. The amount of potassium iodide in the aqueous solution can be from 0.1 parts by mass to 20 parts by mass per 100 parts by mass of water. The temperature of the aqueous solution can be 50°C or higher, for example, from 50°C to 85°C.

The boric acid-treated polyvinyl alcohol-based resin film is typically washed with water. This washing process can be performed, for example, by immersing the boric acid-treated polyvinyl alcohol-based resin film in water. The water temperature during the washing process is typically between 5°C and 40°C. After washing, the film is dried to obtain the polarizer 1.

Drying can be performed using a hot air dryer or a far-infrared heater. A thermoplastic resin film, such as a protective film, can be bonded to one or both sides of the polarizer 1 using an adhesive to obtain the polarizing plate 10.

Another example of a method for manufacturing the polarizer 1 includes the methods described in Japanese Patent Application Publication No. 2000-338329 or Japanese Patent Application Publication No. 2012-159778. This method involves applying a solution containing a polyvinyl alcohol-based resin to the surface of a substrate film, forming a resin layer, and then extending the laminated film formed by the substrate film and the resin layer. The laminated film is then subjected to dyeing and crosslinking treatments to form a polarizer layer (polarizer) from the resin layer. This polarizing laminated film formed by the substrate film and the polarizer layer can then be laminated to the polarizer layer with a thermoplastic resin film as a protective film, and then the substrate film can be removed to produce a polarizing plate 10 having a thermoplastic resin film on one side of the polarizer. By further laminating a thermoplastic resin film to the polarizer layer exposed by peeling the substrate film, a polarizing plate 10 with thermoplastic resin films on both sides of the polarizer can be obtained.

The thickness of the polarizer 1 can be set to 40 μm or less, preferably 30 μm or less.

According to the method described in Japanese Patent Publication No. 2000-338329 or Japanese Patent Publication No. 2012-159778, a thin film polarizer 1 can be easily manufactured, and the thickness of the polarizer 1 can be more easily made, for example, less than 20 μm, further less than 15 μm, and further less than 10 μm or less than 8 μm. The thickness of the polarizer 1 is usually greater than 2 μm, preferably greater than 5 μm, and more preferably greater than 10 μm. The thickness of the polarizer 1 can be greater than 20 μm. A smaller thickness of the polarizer 1 is beneficial to the polarizing plate 10, and also to the thinning of the polarizing plate 25 with an adhesive layer or a laminated optical component or image display device. On the other hand, an increased thickness of the polarizer 1 increases the polarization degree of the polarizing plate 10 and also plays a beneficial role in the durability of the polarizer 1. Therefore, the thickness of the polarizer 1 can be appropriately selected according to the application.

[2-2] 1st protective film and 2nd protective film

The first protective film 4 and the second protective film 3 are bonded to the surface of the polarizer 1. The first protective film 4 and the second protective film 3 are preferably thermoplastic resin films.

Thermoplastic resin films are light-transmitting (preferably optically transparent) thermoplastic resins, and may be, for example, polyolefin resins such as chain polyolefin resins (such as polypropylene resins) and cyclic polyolefin resins (such as norbornene resins); cellulose ester resins such as cellulose triacetate and cellulose diacetate; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; polycarbonate resins; (meth)acrylic resins; or mixtures or copolymers thereof.

The thermoplastic resin film may be an unstretched film or a uniaxially or biaxially stretched film. Biaxial stretching may be simultaneous biaxial stretching, in which the film is stretched simultaneously in two stretching directions, or sequential biaxial stretching, in which the film is stretched in a first direction and then in a second, different direction.

The thermoplastic resin film can be a protective film that protects the polarizer 1, or it can be a protective film that also has optical functions such as a retardation film.

Retardation films are optically functional films used to compensate for the phase difference of liquid crystal cells in image display devices. For example, these films can be formed by stretching (uniaxially or biaxially) a thermoplastic resin, or by forming a liquid crystal layer on the thermoplastic resin film to impart a desired phase difference value.

In addition to homopolymers of chain polyolefins such as polyethylene resins and polypropylene resins, chain polyolefin resins also include copolymers formed from two or more chain polyolefins.

Cyclic polyolefin resins are a general term for resins containing cyclic alkenes as polymeric units, exemplified by norbornene, tetracyclododecene (also known as dimethyloctahydronaphthalene), or their derivatives. Examples of cyclic polyolefin resins include ring-opening (co)polymers of cyclic alkenes and their hydrogenated derivatives, addition polymers of cyclic alkenes, copolymers of cyclic alkenes with chain alkenes such as ethylene and propylene, or aromatic compounds containing vinyl groups, and modified (co)polymers of these with unsaturated carboxylic acids or their derivatives.

Among them, the cyclic olefin is preferably a norbornene resin, and the norbornene resin uses a norbornene monomer such as norbornene or a polycyclic norbornene monomer.

Cellulose ester resins are resins in which at least a portion of the hydroxyl groups in cellulose are esterified with acetic acid. They may also be mixed esters in which a portion is esterified with acetic acid and a portion is esterified with another acid. Cellulose ester resins are preferably cellulose acetate resins.

Cellulose acetate resins include cellulose triacetate, cellulose diacetate, cellulose acetate propionate, cellulose acetate butyrate, etc.

Polyester resins are resins other than the above-mentioned cellulose ester resins that have ester bonds and are generally formed from polycondensates of polycarboxylic acids or their derivatives and polyols.

Examples of polyester resins include polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polybutylene naphthalate, polytrimethylene terephthalate, polytrimethylene naphthalate, polycyclohexane dimethyl terephthalate, and polycyclohexane dimethyl naphthalate.

Other copolymer components may include dicarboxylic acid components or diol components.

Examples of dicarboxylic acid components include isophthalic acid, 4,4'-dicarboxybiphenyl, 4,4'-dicarboxydiphenyl ketone, bis(4-carboxyphenyl)ethane, adipic acid, sebacic acid, 5-sulfoisophthalic acid sodium, and 1,4-dicarboxycyclohexane.

Examples of glycol components include: propylene glycol, butylene glycol, neopentyl glycol, diethylene glycol, cyclohexanediol, bisphenol A ethylene oxide adducts, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc.

Two or more dicarboxylic acid components or diol components may be used in combination as needed.

Furthermore, the above-mentioned dicarboxylic acid component and diol component may also be used together with a hydroxycarboxylic acid such as p-hydroxybenzoic acid, p-hydroxyethoxybenzoic acid, or β-hydroxyethoxybenzoic acid.

Other copolymer components may include small amounts of dicarboxylic acid components and/or diol components having amide bonds, urethane bonds, ether bonds, carbonate bonds, etc.

Polycarbonate resins are polyesters formed from carbonic acid and ethylene glycol or bisphenol. Aromatic polycarbonates containing diphenylalkanes in their molecular chains are preferred for their heat resistance, weather resistance, and acid resistance.

Examples of polycarbonates include polycarbonates derived from bisphenols such as 2,2-bis(4-hydroxyphenyl)propane (also known as bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, 1,1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)isobutane, and 1,1-bis(4-hydroxyphenyl)ethane.

(Meth)acrylic resins may be, for example, polymers containing methacrylate as the main monomer (containing 50% by mass or more), preferably copolymers containing methacrylate and other copolymer components.

In one preferred embodiment, the (meth)acrylic resin contains methyl methacrylate as a copolymerization component, or contains methyl methacrylate and methyl acrylate.

Other copolymer components besides methyl acrylate include, for example, ethyl methacrylate, n-butyl, iso-butyl, or t-butyl methacrylate, cyclohexyl methacrylate, phenyl methacrylate, benzyl methacrylate, 2-ethylhexyl methacrylate, 2-hydroxyethyl methacrylate, and other methacrylates besides methyl methacrylate;

Acrylates such as ethyl acrylate, n-butyl, iso-butyl or t-butyl acrylate, cyclohexyl acrylate, phenyl acrylate, benzyl acrylate, 2-ethylhexyl acrylate, and 2-hydroxyethyl acrylate;

Methyl 2-(hydroxymethyl)acrylate, methyl 2-(1-hydroxyethyl)acrylate, ethyl 2-(hydroxymethyl)acrylate, n-butyl, iso-butyl, or t-butyl 2-(hydroxymethyl)acrylate, and other hydroxyalkyl acrylates;

Unsaturated acids such as methacrylic acid and acrylic acid;

Halogenated styrenes such as chlorostyrene and bromostyrene;

Substituted styrenes such as vinyltoluene and α-methylstyrene;

Unsaturated nitriles such as acrylonitrile and methacrylonitrile;

Unsaturated anhydrides such as maleic anhydride and conic anhydride;

Unsaturated imides such as phenylmaleimide and cyclohexylmaleimide;

etc. monofunctional monomers.

The above-mentioned other monofunctional monomers may be used alone or in combination of two or more.

Multifunctional monomers can also be used as other copolymer components mentioned above.

Examples of multifunctional monomers include ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, nonaethylene glycol di(meth)acrylate, tetradecaethylene glycol di(meth)acrylate, and other ethylene glycol or oligomers thereof, wherein both terminal hydroxyl groups are esterified with (meth)acrylate.

Propylene glycol or its oligomers whose terminal hydroxyl groups are esterified with (meth)acrylate;

Diols such as neopentyl glycol di(meth)acrylate, hexanediol di(meth)acrylate, and butanediol di(meth)acrylate whose hydroxyl groups have been esterified with (meth)acrylate;

Bisphenol A, alkylene oxide adducts of bisphenol A, or halogen-substituted products thereof in which both terminal hydroxyl groups are (meth)acrylated;

Polyols such as trihydroxymethylpropane and pentaerythritol esterified with (meth)acrylate, and those obtained by ring-opening addition of the epoxy group of glycidyl (meth)acrylate to such terminal hydroxyl groups;

Dibasic acids such as succinic acid, adipic acid, terephthalic acid, phthalic acid, and their halogenated derivatives, or the ring-opening addition of the epoxy group of glycidyl (meth)acrylate to their alkylene oxide adducts;

Aryl (meth)acrylates; aromatic divinyl compounds such as divinylbenzene;

wait.

Among them, ethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate, and neopentyl glycol dimethacrylate are preferred.

(Meth)acrylic resins can be modified by reactions between functional groups within the copolymer. Examples of such reactions include the intramolecular demethylation condensation reaction between the methyl ester group of methyl (meth)acrylate and the hydroxyl group of methyl 2-(hydroxymeth)acrylate, and the intramolecular dehydration condensation reaction between the carboxyl group of (meth)acrylic acid and the hydroxyl group of methyl 2-(hydroxymeth)acrylate.

The glass transition temperature of (meth)acrylic resins is preferably between 80°C and 160°C. The glass transition temperature can be controlled by adjusting the polymerization ratio of methacrylate monomers to acrylate monomers, the carbon chain length of each ester group, the type of functional groups present, and the polymerization ratio of the multifunctional monomer relative to the total monomer content.

An effective method for increasing the glass transition temperature of (meth)acrylic resins is to introduce a ring structure into the polymer backbone. Preferred ring structures include heterocyclic structures such as cyclic anhydride structures, cyclic imide structures, and lactone structures. Specific examples include: cyclic anhydride structures such as glutaric anhydride and succinic anhydride structures; cyclic imide structures such as glutarimide and succinimide structures; and lactone ring structures such as butyrolactone and valerolactone.

The higher the ring structure content in the main chain, the higher the glass transition temperature of the (meth)acrylic resin tends to be.

Cyclic anhydride and cyclic imide structures can be introduced by the following methods: copolymerization of monomers with cyclic structures such as maleic anhydride and maleimide; introduction of cyclic anhydride structures through post-polymerization dehydration/demethanolation condensation reactions; and introduction of cyclic imide structures through the reaction of amino compounds.

Resins (polymers) with a lactone ring structure can be obtained by the following method: After preparing a polymer having hydroxyl and ester groups in the polymer chain, the hydroxyl and ester groups in the obtained polymer are subjected to cyclocondensation by heating in the presence of a catalyst such as an organophosphorus compound to form a lactone ring structure.

(Meth)acrylic resins and thermoplastic resin films formed therefrom may contain additives as needed. Examples of additives include lubricants, anti-caking agents, thermal stabilizers, antioxidants, antistatic agents, light-resistant agents, impact resistance improvers, and surfactants.

These additives can also be used when using a thermoplastic resin other than a (meth)acrylic resin as the thermoplastic resin constituting the thermoplastic resin film.

From the perspectives of film formability and impact resistance, (meth)acrylic resins may contain acrylic rubber particles, which act as an impact modifier. Acrylic rubber particles are particles that essentially contain an elastic polymer primarily composed of acrylates. They can have a single-layer structure consisting essentially of this elastic polymer, or a multi-layer structure containing this elastic polymer as a single layer.

Examples of the above-mentioned elastic polymer include crosslinked elastic copolymers containing an acrylic acid alkyl group as a main component, copolymerized with other vinyl monomers copolymerizable therewith and a crosslinking monomer.

Examples of alkyl acrylates used as the main component of the elastic polymer include methyl acrylate, ethyl acrylate, butyl acrylate, and 2-ethylhexyl acrylate, wherein the alkyl group has an alkyl group of 1 to 8 carbon atoms. Alkyl acrylates having an alkyl group of 4 or more carbon atoms are preferred.

Other vinyl monomers that can be copolymerized with the aforementioned alkyl acrylates include compounds having one polymerizable carbon-carbon double bond in the molecule. More specifically, they include methacrylates such as methyl methacrylate; aromatic vinyl compounds such as styrene; and vinyl cyanide compounds such as acrylonitrile.

Examples of the crosslinking monomer include crosslinking compounds having at least two polymerizable carbon-carbon double bonds within the molecule. More specifically, examples include (meth)acrylates of polyols such as ethylene glycol di(meth)acrylate and butanediol di(meth)acrylate; (meth)acrylic acid esters such as allyl (meth)acrylate; and divinylbenzene.

A laminate of a film formed from a (meth)acrylic resin without rubber particles and a film formed from a (meth)acrylic resin containing rubber particles can be bonded to the polarizer 1 as a thermoplastic resin film. Furthermore, a (meth)acrylic resin layer exhibiting retardation formed on one or both sides of a retardation-exhibiting layer formed from a resin different from the (meth)acrylic resin can be bonded to the polarizer 1 as a thermoplastic resin film.

The thermoplastic resin film may contain a UV absorber. When the polarizing plate 10 is used in an image display device such as a liquid crystal display, the thermoplastic resin film containing the UV absorber may be placed on the viewing side of the image display element (e.g., a liquid crystal cell) to suppress degradation of the image display element due to UV rays.

Examples of UV absorbers include salicylate compounds, phenyl ketone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel wax salt compounds.

When thermoplastic resin films are laminated to both surfaces of the polarizer 1, these thermoplastic resin films may be composed of the same thermoplastic resin or different thermoplastic resins. Furthermore, these thermoplastic resin films may be the same or different in thickness, the presence and type of additives, and retardation characteristics.

The second protective film 3 may have a surface treatment layer 2 (coating layer) on its outer surface (the surface opposite to the polarizer 1) such as a hard coating layer, an anti-glare layer, an anti-reflection layer, a light diffusion layer, an anti-static layer, an anti-fouling layer, and a conductive layer.

The thickness of the thermoplastic resin film is typically between 5 μm and 200 μm, preferably between 10 μm and 120 μm, more preferably between 10 μm and 85 μm, and even more preferably between 15 μm and 60 μm. The thickness of the thermoplastic resin film can be between 50 μm and 40 μm. Reducing the thickness of the thermoplastic resin film is beneficial for the polarizing plate 10, as well as for thinning polarizing plates with adhesive layers, laminated optical components, or image display devices.

To improve adhesion, the adhesive surface of the thermoplastic resin film can be treated with surface modification treatments such as saponification, plasma treatment, corona treatment, and primer treatment. However, to simplify the process, surface modification is not necessary.

When the thermoplastic resin membrane is a cellulose acetate-based resin membrane, it is preferably subjected to a saponification treatment from the perspective of improving adhesion. Saponification treatment can be performed by immersing the membrane in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide.

[2-3] The first protective film 4 of the polarizing plate 25 with an adhesive layer shown in Figure 1

The above-mentioned thermoplastic resin film can be used as the first protective film 4 of the polarizing plate 25 with an adhesive layer shown in FIG1 , and a polar resin film is preferably used. By forming a structure in which the first protective film 4, which is a polar resin film, is in contact with the adhesive layer 20, a polarizing plate with an adhesive layer that satisfies the relationship of formula (1) can be easily formed. The antistatic agent contained in the adhesive layer 20 is easily transferred to the first protective film 4, which is a polar resin film. Therefore, it is estimated that a polarizing plate with an adhesive layer that satisfies the relationship of formula (1) can be obtained.

Polar resin membranes are membranes containing polar resins. Polar resins are resins with hydrophilic functional groups in their side chains or main chains. Examples of hydrophilic functional groups include hydroxyl groups, acetyl groups, carboxyl groups, carbonyl groups, amide groups, and cyano groups. Examples of polar resins include cellulose resins, acrylic resins, melamine resins, and polyvinyl alcohol resins. Cellulose ester resins are preferred.

Cellulose ester resins are resins in which at least a portion of the hydroxyl groups in cellulose are esterified with acetic acid. They may also be mixed esters in which a portion is esterified with acetic acid and a portion is esterified with other acids. Cellulose acetate resins are preferably cellulose acetate resins. Examples of cellulose acetate resins include cellulose triacetate, cellulose diacetate, cellulose acetate propionate, and cellulose acetate butyrate. Among these, cellulose triacetate is preferred.

In order to easily form a polarizing plate with an adhesive layer that satisfies the relationship of formula (1), the polar resin film used as the first protective film 4 preferably has a water absorption rate of 1% or more, and more preferably 3% or more. The water absorption rate of the polar resin film is preferably 8% or less. The water absorption rate is a value measured in accordance with "Test method for water absorption and boiling water absorption of plastics" described in JIS K 7209. The water absorption rate is obtained by immersing a 50mm square test piece in water at a temperature of 23°C for 24 hours and measuring the weight change before and after immersion. The unit is %.

The polar resin film used as the first protective film 4 preferably has a moisture permeability of 300 g/m ² ·24h or more, more preferably 500 g/m ² ·24h or more, based on a thickness of 40 μm, in order to easily form a polarizing plate with an adhesive layer satisfying the relationship of formula (1). The polar resin film preferably has a moisture permeability of 5000 g/m ² ·24h or less. The moisture permeability is a value measured in accordance with JIS K7129:2008 Annex B in a gas environment at a temperature of 40°C and a humidity of 90% RH.

The polar resin film used as the first protective film 4 preferably has a volume resistivity of 1.0×10 ² Ω·cm to 1.0×10 ⁴ Ω·cm in order to easily form a polarizing plate with an adhesive layer satisfying the relationship of formula (1).

[2-4] Hardening layer of hardening resin composition

The curable resin composition curing layer 5 is formed by applying and curing a curable resin composition. It is formed by applying and curing the curable resin composition onto the surface of the polarizer 1 in the adhesive layer-attached polarizing plate 26 shown in Figure 2 and onto the surface of the first protective film 4 in the adhesive layer-attached polarizing plate 27 shown in Figure 3.

Curable resin compositions include thermosetting resins, UV-curable resins, electron beam-curable resins, and other curable resins. Examples of curable resins include polyesters, acrylics, polyurethanes, acrylic polyurethanes, amides, silicones, silicates, epoxies, melamines, cyclohexanes, and acrylic polyurethanes. One or more of these curable resins can be selected and used as appropriate.

Among these, acrylic resins, acrylic-based urethane resins, and epoxy resins are preferred due to their high hardness, UV curability, and excellent productivity. Epoxy resins and cyclohexane resins are particularly preferred. UV-curable resins include UV-curable monomers, oligomers, and polymers. Preferred UV-curable resins include those containing UV-polymerizable functional groups, including monomers and oligomers of epoxy and cyclohexane resins containing two or more, particularly three to six, such functional groups.

By connecting the curable resin composition hardening layer 5 and the adhesive layer 20, a polarizing plate with an adhesive layer that satisfies the relationship of formula (1) can be easily constructed. The antistatic agent contained in the adhesive layer 20 easily migrates to the curable resin composition hardening layer 5, and therefore, it is estimated that a polarizing plate with an adhesive layer that satisfies the relationship of formula (1) is obtained.

[2-5] Manufacturing of polarizing plates

The adhesive used to bond the first protective film 4 and/or the second protective film 3 (hereinafter sometimes collectively referred to as "protective films") to the polarizer 1 may be a water-based adhesive or an active energy ray-curable adhesive.

Examples of water-based adhesives include conventionally known adhesive compositions using polyvinyl alcohol-based resins or polyurethane resins as main components.

When a polyvinyl alcohol resin is used as the main component of the adhesive, the polyvinyl alcohol resin may be a partially saponified polyvinyl alcohol, a completely saponified polyvinyl alcohol, or a modified polyvinyl alcohol resin.

Polyvinyl alcohol resins include vinyl alcohol homopolymers obtained by saponifying polyvinyl acetate, which is a vinyl acetate homopolymer, and polyvinyl alcohol copolymers obtained by saponifying copolymers of vinyl acetate and other copolymerizable monomers.

To improve adhesion, water-based adhesives containing polyvinyl alcohol resins may contain hardening ingredients or crosslinking agents such as polyaldehydes, melamine compounds, zirconium oxide compounds, zinc compounds, glyoxal, glyoxal derivatives, and water-soluble epoxy resins.

Examples of water-based adhesives containing polyurethane resins as their main component include those containing polyester ionomer-type polyurethane resins and compounds having glycidyloxy groups. Polyester ionomer-type polyurethane resins are polyurethane resins with a polyester backbone into which a small amount of ionic components (hydrophilic components) are introduced.

Active energy ray-curable adhesives are adhesives that cure by exposure to active energy rays, such as ultraviolet rays, visible light, electron beams, and X-rays. When using an active energy ray-curable adhesive, the adhesive layer of the polarizing plate 10 is a cured layer of the adhesive.

Active energy ray-curable adhesives can be those containing an epoxy compound that cures by cationic polymerization as a curing component. Preferably, they are UV-curable adhesives containing such an epoxy compound as a curing component. An epoxy compound is a compound having an average of one or more, preferably two or more, epoxy groups per molecule. One epoxy compound may be used alone or in combination.

Examples of epoxy compounds include: alicyclic polyols obtained by hydrogenating the aromatic ring of an aromatic polyol, and then reacting the resulting alicyclic polyol with epichlorohydrin to obtain a hydroepoxy compound (glycidyl ether of a polyol having an alicyclic ring); aliphatic epoxy compounds such as polyglycidyl ethers of aliphatic polyols or their alkylene oxide adducts; and alicyclic epoxy compounds that are epoxy compounds having one or more epoxy groups bonded to an alicyclic ring in the molecule.

As for the curing component, the active energy ray-curable adhesive may contain a free-radically polymerizable (meth)acrylic compound, either in place of or in addition to the epoxy compound. Examples of (meth)acrylic compounds include (meth)acrylate monomers having one or more (meth)acryloyloxy groups in the molecule; (meth)acrylate oligomers having at least two (meth)acryloyloxy groups in the molecule obtained by reacting two or more functional group-containing compounds; and other (meth)acryloyloxy-containing compounds.

When an active energy ray-curable adhesive contains an epoxy compound that cures by cationic polymerization as a curing component, it preferably contains a photocationic polymerization initiator. Examples of photocationic polymerization initiators include aromatic oxadiazolium salts; onium salts such as aromatic iodonium salts or aromatic stibnium salts; and iron-allene complexes.

When an active energy ray-curable adhesive contains a radically polymerizable component such as a (meth)acrylic compound, it preferably contains a photoradical polymerization initiator. Examples of photoradical polymerization initiators include acetophenone-based initiators, diphenyl ketone-based initiators, benzoin ether-based initiators, thioxanthrone-based initiators, oxanthrone, fluorenone, camphorquinone, benzaldehyde, and anthraquinone.

The bonding process between the polarizer 1 and the first protective film 4 or the second protective film 3 may include, for example, applying an adhesive to the bonding surface of the polarizer 1 and/or the bonding surface of the protective film, or injecting an adhesive between the polarizer 1 and the thermoplastic resin film, superimposing the two films with the adhesive layer interposed therebetween, and laminating them by pressing from above and below using a laminating roller or the like.

The adhesive layer can be formed using various coating methods, including doctor blade coating, wire rod coating, die coating, comma coating, and gravure coating. Alternatively, the adhesive can be continuously supplied while casting between the polarizer 1 and the protective film, with the bonding surfaces facing inward.

Before applying the adhesive, one or both of the polarizer 1 and the bonding surface of the protective film may be subjected to a bonding-facilitating treatment (surface activation treatment) such as saponification, corona discharge treatment, plasma treatment, flame treatment, primer treatment, or anchor coating treatment.

When using an active energy ray-curable adhesive, after drying the adhesive layer as needed, irradiate with active energy rays to cure the adhesive layer.

The light source used to irradiate the active energy rays can be any light source capable of generating ultraviolet rays, electron beams, X-rays, etc. Particularly suitable are those with a luminescence distribution below a wavelength of 400 nm. Examples include low-pressure mercury lamps, medium-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, chemical lamps, black light lamps, microwave-excited mercury lamps, and metal halide lamps.

In the obtained polarizing plate 10, the thickness of the adhesive layer formed by the aqueous adhesive is, for example, not less than 10 nm and not more than 10 μm, preferably not less than 20 nm and not more than 5 μm, more preferably not less than 30 nm and not more than 1 μm, and even more preferably not less than 40 nm and not more than 500 nm.

The thickness of the adhesive layer formed by the active energy ray-curable adhesive is, for example, not less than 10 nm and not more than 20 μm, preferably not less than 100 nm and not more than 10 μm, and more preferably not less than 500 nm and not more than 5 μm.

When protective films are laminated on both sides of the polarizer 1, the thicknesses of the two adhesive layers can be the same or different.

[2-6] Other components of polarizing plates

The polarizing plate 10 may include other optically functional films in addition to the polarizer 1 to impart the desired optical function. A suitable example is a retardation film.

As mentioned above, the protective film can also serve as a retardation film, but the retardation film can also be laminated separately from the protective film. The retardation film can be laminated on the outside of the protective film via an adhesive layer or a bonding agent layer, or it can be laminated on the surface of the polarizer 1.

Examples of retardation films include: a birefringent film made of a stretched film of a light-transmitting thermoplastic resin; a film with aligned and fixed discotic liquid crystal or nematic liquid crystal; and a film having the above-mentioned liquid crystal layer formed on a substrate film.

The base film is usually a film formed of a thermoplastic resin. An example of a thermoplastic resin is a cellulose ester resin such as cellulose triacetate.

Thermoplastic resins for forming birefringent films may be those described in the section on thermoplastic resin films.

Examples of other optically functional films (optical components) that may be included in the polarizing plate 10 include a light-collecting plate, a brightness-enhancing film, a reflective layer (reflective film), a semi-transmissive reflective layer (semi-transmissive reflective film), and a light-diffusing layer (light-diffusing film). These are generally provided when the polarizing plate 10 is positioned on the back side (backlight side) of the liquid crystal cell.

Light collecting plates are used for purposes such as light path control and can be prism array plates, lens array plates, point-connected plates, etc.

Brightness-enhancing films are used to increase the brightness of liquid crystal displays (LCDs) using polarizing plates 10. Specifically, they include reflective polarizing films designed to produce anisotropy in reflectivity by laminating multiple thin films with mutually opposite refractive indices; and circular polarizing films in which an alignment film of a steric liquid crystal polymer or its aligned liquid crystal layer is supported on a substrate film.

The reflective layer, transflective reflective layer, and light-diffusing layer are optical components that can be provided to configure the polarizer 10 as a reflective, transflective, or diffusing type, respectively. Reflective polarizers are used in liquid crystal display devices that reflect incident light from the viewing side to display the image. This eliminates the need for a backlight or other light source, making the display thinner. Transflective polarizers are used in liquid crystal display devices that reflect light in bright areas and display light from the backlight in dark areas. Furthermore, diffusing polarizers are used in liquid crystal display devices to impart light diffusivity and suppress display defects such as clouding. The reflective layer, transflective reflective layer, and light-diffusing layer can be formed using known methods.

The polarizing plate 10 may include a protective film to protect the surface opposite to the side on which the adhesive layer 20 is laminated (typically, the viewing side). This protective film is removed when the adhesive layer is peeled off after the polarizing plate with the adhesive layer is attached to an optical component such as an image display device.

The protective film is composed of, for example, a base film and an adhesive layer stacked thereon.

The resin constituting the substrate film may be, for example, a polyethylene resin such as polyethylene, a polypropylene resin such as polypropylene, a polyester resin such as polyethylene terephthalate or polyethylene naphthalate, or a thermoplastic resin such as a polycarbonate resin. Polyester resins such as polyethylene terephthalate are preferred.

[3] Adhesive layer

The adhesive layer 20 constituting the polarizing plates 25, 26, and 27 with adhesive layers is formed of an adhesive composition.

[3-1] (Meth) acrylic resin

From the perspectives of the optical properties (transparency, polarization properties, etc.) of the adhesive-coated polarizing plate and the adhesion between the adhesive-coated polarizing plate and other optical components, the adhesive composition preferably contains a (meth)acrylic resin. The adhesive composition may contain one or more (meth)acrylic resins.

In this specification, "(meth)acrylate" refers to acrylate and/or methacrylate. This also applies to "(meth)" when using (meth)acrylate, etc.

The heat durability mentioned above refers to the resistance to adverse conditions such as lifting or peeling of the adhesive layer at the interface with other optical components, and bubbling of the adhesive layer, which can occur when the laminated optical component is exposed to high temperatures or in an environment with repeated high and low temperatures.

From the perspectives of the optical properties (transparency, polarization properties, etc.) of the polarizing plate with the adhesive layer, as well as the adhesion between the adhesive layer and other optical components, the (meth)acrylic resin is preferably a polymer containing as its main component a constituent unit derived from a (meth)acrylate represented by the following formula (I).

The main component means a component that accounts for 50% by mass or more of all the constituent units of the (meth)acrylic resin.

In the above formula (I), ^R1 represents a hydrogen atom or a methyl group; ^R2 represents an alkyl group having 1 to 14 carbon atoms which may be substituted with an alkoxy group having 1 to 10 carbon atoms, or an aralkyl group having 7 to 21 carbon atoms which may be substituted with an alkoxy group having 1 to 10 carbon atoms. When an aralkyl group is substituted with an alkoxy group, the carbon number of the aralkyl group is the number excluding the carbon atoms of the alkoxy group.

R ² is preferably an alkyl group having 1 to 14 carbon atoms which may be substituted with an alkoxy group having 1 to 10 carbon atoms, and more preferably an alkyl group having 1 to 14 carbon atoms which is not substituted with an alkoxy group.

Examples of the (meth)acrylate represented by formula (I) include: alkyl (meth)acrylates having a linear alkyl ester portion, such as methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, n-butyl (meth)acrylate, n-octyl (meth)acrylate, and dodecyl (meth)acrylate; and alkyl (meth)acrylates having a branched alkyl ester portion, such as isobutyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and isooctyl (meth)acrylate.

When R ² is an alkyl group substituted with an alkoxy group, that is, when R ² is an alkoxyalkyl group, examples of the (meth)acrylate represented by formula (I) include 2-methoxyethyl (meth)acrylate and ethoxymethyl (meth)acrylate.

When R ² is an aralkyl group having 7 to 21 carbon atoms, examples of the (meth)acrylate represented by formula (I) include benzyl (meth)acrylate and the like.

The (meth)acrylate represented by formula (I) may be used alone or in combination of two or more. Among them, the (meth)acrylate preferably contains n-butyl acrylate.

The (meth)acrylic resin preferably contains 50% by mass or more, more preferably 55% by mass or more, of the total units comprising the (meth)acrylic resin. The content of units derived from n-butyl acrylate in the total units comprising the (meth)acrylic resin is generally 90% by mass or less, preferably 85% by mass or less, more preferably 80% by mass or less, and even more preferably 75% by mass or less.

In addition to n-butyl acrylate, other (meth)acrylates represented by formula (I) may also be used in combination. For example, the (meth)acrylic resin preferably contains constituent units derived from n-butyl acrylate and constituent units derived from methyl acrylate. When the (meth)acrylic resin contains constituent units derived from n-butyl acrylate and constituent units derived from methyl acrylate, the content of the constituent units derived from n-butyl acrylate is as described above. The content of the constituent units derived from methyl acrylate in the total constituent units constituting the (meth)acrylic resin is generally 1% by mass to 50% by mass, preferably 5% by mass to 45% by mass, and more preferably 10% by mass to 40% by mass.

From the perspectives of the optical properties (transparency, polarization properties, etc.) of the polarizing plate with the adhesive layer, and the adhesion between the adhesive layer and other optical components, the content of units derived from the (meth)acrylate represented by formula (I) in all the units constituting the (meth)acrylic resin is preferably 60% by mass or more and less than 100% by mass, more preferably 70% by mass or more and less than 99.9% by mass, and even more preferably 80% by mass or more and less than 99.6% by mass.

(Meth)acrylic resins may contain constituent units derived from (meth)acrylic monomers having a hydroxyl group.

Examples of the (meth)acrylic monomer having a hydroxyl group include (meth)acrylates having a hydroxyl group.

Examples of (meth)acrylates having a hydroxyl group include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-(2-hydroxyethoxy)ethyl (meth)acrylate, 2- or 3-chloro-2-hydroxypropyl (meth)acrylate, and diethylene glycol mono(meth)acrylate.

From the perspectives of adhesive layer processability and adhesion to other optical components, the content of units derived from (meth)acrylic monomers having hydroxyl groups in the total units constituting the (meth)acrylic resin is preferably from 0.1% to 5% by mass, and more preferably from 0.5% to 4% by mass.

(Meth)acrylic resins may contain constituent units derived from monomers having other polar functional groups in addition to (meth)acrylic monomers having hydroxyl groups. Monomers having other polar functional groups are preferably (meth)acrylic monomers having other polar functional groups.

Examples of polar functional groups possessed by monomers having other polar functional groups include carboxyl groups (free carboxyl groups), amino groups, heterocyclic groups (such as epoxy groups), and amide groups.

Examples of monomers with other polar functional groups include:

Monomers containing a carboxyl group, such as (meth)acrylic acid and β-carboxyethyl (meth)acrylate ((meth)acrylic acid-based monomers containing a carboxyl group);

(Meth)acryloylmorpholine, vinylcaprolactam, N-vinyl-2-pyrrolidone, vinylpyridine, tetrahydrofuryl (meth)acrylate, caprolactone-modified tetrahydrofuryl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, glycidyl (meth)acrylate, 2,5-dihydrofuran, and other monomers with heterocyclic groups;

Monomers containing amino groups other than heterocyclic groups, such as aminoethyl (meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, and dimethylaminopropyl (meth)acrylate.

Monomers with other polar functional groups may be used alone or in combination of two or more.

From the perspective of adhesion between the adhesive layer and other optical components, the content of constituent units derived from monomers having other polar functional groups is preferably from 0.1% to 5% by mass, and more preferably from 0.5% to 3% by mass, based on the total constituent units of the (meth)acrylic resin.

The (meth)acrylic resin may further contain constituent units derived from monomers having one olefinic double bond and at least one aromatic ring in the molecule (however, excluding monomers corresponding to the above formula (I) or the above polar functional groups).

Containing a structural unit derived from a monomer having one olefinic double bond and at least one aromatic ring in the molecule is advantageous from the perspective of effectively suppressing the occurrence of white discoloration or color unevenness in a laminated optical component.

Examples of monomers having one olefinic double bond and at least one aromatic ring in the molecule include (meth)acrylic monomers having an aromatic ring.

Examples of (meth)acrylic monomers having an aromatic ring include neopentyl glycol benzoate (meth)acrylate and (meth)acrylates having an aryloxyalkyl group, such as the (meth)acrylate containing a phenoxyethyl group represented by the following formula (II). Preferred are (meth)acrylates having an aryloxyalkyl group.

In formula (II), ^R represents a hydrogen atom or a methyl group, i represents an integer from 1 to 8, and ^R represents a hydrogen atom, an alkyl group, an aralkyl group, or an aryl group. When ^R is an alkyl group, the carbon number thereof may be from 1 to 9, when it is an aralkyl group, the carbon number thereof may be from 7 to 11, and when it is an aryl group, the carbon number thereof may be from 6 to 10.

In formula (II), the alkyl group having 1 to 9 carbon atoms constituting ^R4 may include methyl, butyl, nonyl, etc.; the aralkyl group having 7 to 11 carbon atoms may include benzyl, phenethyl, naphthylmethyl, etc.; and the aryl group having 6 to 10 carbon atoms may include phenyl, tolyl, naphthyl, etc.

Specific examples of the phenoxyethyl group-containing (meth)acrylate represented by formula (II) include 2-phenoxyethyl (meth)acrylate, 2-(2-phenoxyethoxy)ethyl (meth)acrylate, ethylene oxide-modified nonylphenol (meth)acrylate, and 2-(o-phenylphenoxy)ethyl (meth)acrylate.

Phenoxyethyl-containing (meth)acrylates may be used alone or in combination of two or more.

Among them, the (meth)acrylate containing a phenoxyethyl group is preferably one or more selected from the group consisting of 2-phenoxyethyl (meth)acrylate, 2-(o-phenylphenoxy)ethyl (meth)acrylate, and 2-(2-phenoxyethoxy)ethyl (meth)acrylate, and more preferably one or two selected from the group consisting of 2-(o-phenylphenoxy)ethyl (meth)acrylate and 2-(2-phenoxyethoxy)ethyl (meth)acrylate.

From the perspective of effectively suppressing white discoloration or color unevenness in laminated optical components, the content of units derived from monomers having one olefinic double bond and at least one aromatic ring in the molecule is preferably from 1 mass% to 20 mass%, and more preferably from 5 mass% to 15 mass%, among all the units constituting the (meth)acrylic resin.

(Meth)acrylic resins may also contain constituent units derived from the (meth)acrylate of formula (I) described above, monomers having polar functional groups, and monomers other than monomers having one olefinic double bond and at least one aromatic ring in the molecule (hereinafter also referred to as "other monomers").

Other monomers include units derived from (meth)acrylates having an alicyclic structure in the molecule, units derived from styrene-based monomers, units derived from vinyl-based monomers, units derived from monomers having multiple (meth)acryloyl groups in the molecule, and units derived from (meth)acrylamide monomers.

Other monomers can be used alone or in combination of two or more.

Containing constituent units derived from other monomers, particularly constituent units derived from (meth)acrylamide monomers, can be advantageous in improving the adhesion between the adhesive layer and other optical components.

The alicyclic structure in (meth)acrylates having an alicyclic structure in the molecule refers to a cyclopentane structure having a carbon number of generally 5 or more, preferably 5 or more and 7 or less.

Examples of (meth)acrylates with an alicyclic structure include isoborneol (meth)acrylate, cyclohexyl (meth)acrylate, dicyclopentyl (meth)acrylate, cyclododecyl (meth)acrylate, methylcyclohexyl (meth)acrylate, trimethylcyclohexyl (meth)acrylate, tert-butylcyclohexyl (meth)acrylate, cyclohexylphenyl (meth)acrylate, and α-ethoxycyclohexyl acrylate.

Examples of styrene monomers include: styrene; alkyl styrenes such as methylstyrene, dimethylstyrene, trimethylstyrene, ethylstyrene, diethylstyrene, triethylstyrene, propylstyrene, butylstyrene, hexylstyrene, heptylstyrene, and octylstyrene; halogenated styrenes such as fluorostyrene, chlorostyrene, bromostyrene, dibromostyrene, and iodostyrene; nitrostyrene, styrene acetate, methoxystyrene, and divinylbenzene.

Examples of vinyl monomers include: fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, and vinyl laurate; vinyl halides such as vinyl chloride and vinyl chloride; vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyls such as vinyl pyridine, vinyl pyrrolidone, and vinyl carbazole; conjugated diene monomers such as butadiene, isoprene, and chloroprene; and acrylonitrile and methacrylonitrile.

Examples of monomers having multiple (meth)acryloyl groups in the molecule include 1,4-butanediol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,9-nonanediol di(meth)acrylate, ethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, and tripropylene glycol di(meth)acrylate; and monomers having three (meth)acryloyl groups in the molecule, such as trihydroxymethylpropane tri(meth)acrylate.

(Meth)acrylamide monomers include: N-hydroxymethyl (meth)acrylamide, N-(2-hydroxyethyl) (meth)acrylamide, N-(3-hydroxypropyl) (meth)acrylamide, N-(4-hydroxybutyl) (meth)acrylamide, N-(5-hydroxypentyl) (meth)acrylamide, N-(6-hydroxyhexyl) (meth)acrylamide, N,N-dimethyl (meth)acrylamide, N,N-diethyl (meth)acrylamide, N-isopropyl (meth) Acrylamide, N-(3-dimethylaminopropyl)(meth)acrylamide, N-(1,1-dimethyl-3-hydroxybutyl)(meth)acrylamide, N-[2-(2-hydroxy-1-imidazolidinyl)ethyl](meth)acrylamide, 2-acrylamido-2-methyl-1-propanesulfonic acid, N-(methoxymethyl)acrylamide, N-(ethoxymethyl)(meth)acrylamide, N-(propyloxymethyl)(meth)acrylamide, N-(1-methylethoxymethyl) )(Meth)acrylamide, N-(1-methylpropoxymethyl)(meth)acrylamide, N-(2-methylpropoxymethyl)(meth)acrylamide [Also known as: N-(isobutoxymethyl)(meth)acrylamide], N-(butoxymethyl)(meth)acrylamide, N-(1,1-dimethylethoxymethyl)(meth)acrylamide, N-(2-methoxyethyl)(meth)acrylamide, N-(2-ethoxyethyl)(meth)acrylamide, N-(2- N-[2-(1-methylethoxy)ethyl](meth)acrylate, N-[2-(1-methylpropoxy)ethyl](meth)acrylate, N-[2-(2-methylpropoxy)ethyl](meth)acrylate [also known as N-(2-isobutoxyethyl)(meth)acrylate], N-(2-butoxyethyl)(meth)acrylate, N-[2-(1,1-dimethylethoxy)ethyl](meth)acrylate, etc. Among them, N-(methoxymethyl)acrylate, N-(ethoxymethyl)acrylate, N-(propoxymethyl)acrylate, N-(butoxymethyl)acrylate, and N-(2-methylpropoxymethyl)acrylate are preferably used.

From the perspective of adhesion between the adhesive layer and other optical components, the (meth)acrylamide monomer is preferably an alkyl (meth)acrylamide monomer that may be substituted with an alkoxy group.

In the alkyl (meth)acrylate amide monomer that may be substituted with an alkoxy group, the number of carbon atoms in the alkoxy group is preferably 1 to 10, and the number of carbon atoms in the alkyl group is preferably 1 to 14. When an alkyl group is substituted with an alkoxy group, the number of carbon atoms in the alkyl group is the number of carbon atoms after removing the carbon atoms in the alkoxy group.

Examples of the alkyl (meth) acrylate amide monomer that may be substituted with an alkoxy group include the alkoxyalkyl (meth) acrylate amide monomer represented by the following formula (III).

In formula (III), R ⁵ represents a hydrogen atom or a methyl group, R ⁶ represents an alkyl group having 1 to 14 carbon atoms, and n represents an integer of 1 to 8.

Alkyl groups include methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-hexyl, n-heptyl, n-octyl, etc.

n is preferably greater than 1 and less than 6.

From the perspective of adhesion between the adhesive layer and other optical components, the content of constituent units derived from other monomers (particularly (meth)acrylamide monomers) is preferably 0.1% by mass to 20% by mass, more preferably 0.2% by mass to 10% by mass, and even more preferably 0.3% by mass to 5% by mass, based on the total constituent units of the (meth)acrylic resin.

From the perspective of adhesion between the adhesive layer and other optical components, the (meth)acrylic resin preferably contains a structural unit derived from a (meth)acrylic monomer having a carboxyl group and a structural unit derived from an alkoxyalkyl (meth)acrylamide monomer.

From the perspective of adhesion between the adhesive layer and other optical components, the total content of the constituent units derived from the (meth)acrylic monomer having a carboxyl group and the constituent units derived from the alkoxyalkyl (meth)acrylamide monomer is preferably from 0.1% to 15% by mass, more preferably from 0.2% to 10% by mass, and even more preferably from 0.3% to 4% by mass, based on the total constituent units of the (meth)acrylic resin.

The (meth)acrylic resin preferably has a weight average molecular weight (Mw) calculated as standard polystyrene based on gel permeation chromatography (GPC) within the range of 500,000 to 2,000,000, and more preferably within the range of 600,000 to 1,800,000. Adhesive compositions containing (meth)acrylic resins having an Mw within this range are advantageous from the perspective of ensuring the handleability of the (meth)acrylic resin during preparation of the adhesive composition.

The molecular weight distribution, represented by the ratio of weight-average molecular weight (Mw) to number-average molecular weight (Mn) (Mw/Mn), is usually between 2 and 10, preferably between 3 and 8.

(Meth)acrylic resins can be produced by known methods such as solution polymerization, bulk polymerization, suspension polymerization, and emulsion polymerization. A polymerization initiator is generally used in the production of (meth)acrylic resins. The amount of the polymerization initiator used is typically 0.001 to 5 parts by mass per 100 parts by mass of all monomers used in the production of the (meth)acrylic resin. Furthermore, (meth)acrylic resins can be produced by polymerization using active energy rays such as ultraviolet light.

The polymerization initiator may be a thermal polymerization initiator or a photopolymerization initiator.

Examples of photopolymerization initiators include 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2-propyl)ketone.

Examples of thermal polymerization initiators include: azo compounds such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2-methylbutyronitrile), 1,1'-azobis(cyclohexane-1-carbonitrile), 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2'-azobis(2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis(2-methylpropionate), and 2,2'-azobis(2-hydroxymethylpropionitrile); dodecyl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxybenzyl ester, and isopropylbenzene hydroperoxide. hydroperoxide), diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, (3,5,5-trimethylhexanoyl) peroxide and other organic peroxides; potassium persulfate, ammonium persulfate, hydrogen peroxide and other inorganic peroxides, etc.

Furthermore, redox initiators that use a peroxide and a reducing agent can also be used as polymerization initiators.

The preferred method for producing (meth)acrylic resins is the solution polymerization method described above. An example of a solution polymerization method involves mixing the monomers and an organic solvent, adding a thermal polymerization initiator, and stirring the mixture at a temperature between 40°C and 90°C, preferably between 50°C and 80°C, for a period of 3 to 15 hours. To control the reaction, the monomers or thermal polymerization initiator may be added continuously or intermittently during polymerization, or they may be added while dissolved in the organic solvent.

Examples of organic solvents include aromatic hydrocarbons such as toluene and xylene; esters such as ethyl acetate and butyl acetate; aliphatic alcohols such as propanol and isopropanol; and ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone.

[3-2] Crosslinking agent

The adhesive composition may further contain a crosslinking agent. A crosslinking agent is a compound that reacts with polar functional groups in the (meth)acrylic resin to crosslink the (meth)acrylic resin.

The crosslinking agent may be selected from isocyanate compounds, epoxy compounds, aziridine compounds, metal chelate compounds, and the like.

Among these, isocyanate compounds, epoxy compounds, and aziridine compounds have at least two functional groups in their molecules that can react with polar functional groups in (meth)acrylic resins.

A single crosslinking agent may be used alone, or two or more may be used in combination.

Isocyanate compounds are compounds with at least two isocyanate groups (-NCO) in their molecules.

Examples of isocyanate compounds include toluene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, xylene diisocyanate, hydrogenated xylene diisocyanate, diphenylmethane diisocyanate, hydrogenated diphenylmethane diisocyanate, naphthalene diisocyanate, and triphenylmethane triisocyanate. Furthermore, adducts obtained by reacting these isocyanate compounds with polyols such as glycerol or trihydroxymethylpropane, or isocyanate compounds converted to dimers or trimers, can also be used as crosslinking agents.

Two or more isocyanate compounds may be used.

Epoxy compounds are compounds with at least two epoxy groups in their molecules.

Examples of epoxy compounds include bisphenol A-type epoxy resins, ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol diglycidyl ether, glycerol triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimethoxypropane triglycidyl ether, N,N-diglycidylaniline, N,N,N',N'-tetraglycidyl-m-xylenediamine, and 1,3-bis(N,N'-diglycidylaminomethyl)cyclohexane.

Two or more epoxy compounds may be used in combination.

Aziridine compounds, also known as ethyleneimines, are compounds that have at least two three-membered ring skeletons formed by one nitrogen atom and two carbon atoms in their molecules.

Examples of aziridine compounds include diphenylmethane-4,4'-bis(1-aziridinecarboxamide), toluene-2,4-bis(1-aziridinecarboxamide), triethylene melamine, m-phenylenediamine bis-1-(2-methylaziridine), tris-1-aziridinylphosphine oxide, hexamethylene-1,6-bis(1-aziridinecarboxamide), trihydroxymethylpropane-tris-β-aziridinyl propionate, and tetrahydroxymethylmethane-tris-β-aziridine propionate.

Two or more aziridine compounds may be used in combination.

Examples of metal chelate compounds include compounds in which acetone acetate or ethyl acetylacetate is coordinated with polyvalent metals such as aluminum, iron, copper, zinc, tin, titanium, nickel, antimony, magnesium, vanadium, chromium, and zirconium.

Two or more metal chelate compounds may be used in combination.

Among them, isocyanate compounds are beneficial in improving the adhesion between the adhesive layer and other optical components.

Among the isocyanate compounds, preferred are xylene diisocyanate, toluene diisocyanate, or hexamethylene diisocyanate; adducts of these isocyanate compounds reacted with polyols such as glycerol or trihydroxymethylpropane; dimers, trimers, or mixtures of these isocyanate compounds; and mixtures of two or more of the isocyanate compounds disclosed above.

Suitable isocyanate compounds include toluene diisocyanate, adducts obtained by reacting toluene diisocyanate with a polyol, dimers of toluene diisocyanate, and trimers of toluene diisocyanate. Furthermore, suitable isocyanate compounds include hexamethylene diisocyanate, adducts obtained by reacting hexamethylene diisocyanate with a polyol, dimers of hexamethylene diisocyanate, and trimers of hexamethylene diisocyanate.

The content of the crosslinking agent in the adhesive composition is generally from 0 to 5 parts by mass, preferably from 0 to 2 parts by mass, per 100 parts by mass of the (meth)acrylic resin. When the adhesive composition contains a crosslinking agent, the lower limit of the content is, for example, 0.05 parts by mass per 100 parts by mass of the (meth)acrylic resin.

[3-3] Antistatic Agent

The adhesive composition contains an antistatic agent for imparting antistatic properties to the adhesive layer 20.

Antistatic agents are preferably ionic compounds. Ionic compounds are compounds containing inorganic or organic cations and inorganic or organic anions.

Two or more ionic compounds can be used.

Examples of inorganic cations include alkaline metal ions such as lithium cation [Li ⁺ ], sodium cation [Na ⁺ ], and potassium cation [K ⁺ ]; or alkaline earth metal ions such as benzene cation [Be ²⁺ ], magnesium cation [Mg ²⁺ ], and calcium cation [Ca ²⁺ ].

Examples of organic cations include imidazolium cations, pyridinium cations, pyrrolidinium cations, ammonium salt cations, coumarin cations, and phosphonium cations.

Among the aforementioned cationic components, organic cationic components that have excellent compatibility with the adhesive composition are preferably used. Among these organic cationic components, pyridinium and imidazolium cations are particularly preferred because they are less likely to be charged when peeling the spacer film provided on the adhesive layer 20.

Examples of inorganic anions include chloride anion [Cl ^- ], bromine anion [Br ^- ], iodine anion [I ^- ], aluminum tetrachloride anion [AlCl ₄ ^- ], aluminum heptachloride anion [Al ₂ Cl ₇ ^- ], boron tetrafluoride anion [BF ₄ ^- ], phosphorus hexafluoride anion [PF ₆ ^- ], perchlorate anion [ClO ₄ ^- ], nitrate anion [NO ₃ ^- ], arsenic hexafluoride anion [AsF 6 - ], antimony hexafluoride anion [SbF ₆ ^- ], niobium hexafluoride anion [NbF ₆ ^- ], tantalum hexafluoride anion [TaF ₆ ^- ], and arsenic hexafluoride anion [AsF ₆ ^{- ]} . ], dicyandiamide anion [(CN) ₂ N ^- ], etc.

Examples of organic anions include acetate anion [CH ₃ COO ^- ], trifluoroacetate anion [CF ₃ COO ^- ], methanesulfonate anion [CH ₃ SO ₃ ^- ], trifluoromethanesulfonate anion [CF ₃ SO ₃ ^- ], p-toluenesulfonate anion [p-CH ₃ C ₆ H ₄ SO ₃ ^- ], bis(fluorosulfonyl)imide anion [(FSO ₂ ) ₂ N ^- ], bis(trifluoromethanesulfonyl)imide anion [(CF ₃ SO ₂ ) ₂ N ^- ], tris(trifluoromethanesulfonyl)methane anion [(CF ₃ SO ₂ ) ₃ C ^- ], dimethylphosphinate anion [(CH ₃ ) ₂ POO ^- ], (poly)hydrofluorofluoride anion [F(HF) _n ^- ] (n is about 1 or more and about 3 or less), thiocyanate anion [SCN ^- ], perfluorobutanesulfonate anion [C ₄ F ₉ SO ₃ ^- ], bis(pentafluoroethanesulfonyl)imide anion [(C ₂ F ₅ SO ₂ ) ₂ N ^- ], perfluorobutyrate anion [C ₃ F ₇ COO ^- ], (trifluoromethanesulfonyl)(trifluoromethanecarbonyl)imide anion [(CF ₃ SO ₂ )(CF ₃ CO)N ^- ], perfluoropropane-1,3-disulfonate anion [ ^- O ₃ S(CF ₂ ) ₃ SO ₃ ^- ], carbonate anion [CO ₃ ^2- ], etc.

Among the above-mentioned anionic components, it is preferred to use anionic components containing fluorine atoms, which are ionic compounds that can provide excellent antistatic properties. Examples of anionic components containing fluorine atoms include bis(fluorosulfonyl)imide anions, hexafluorophosphate anions, or bis(trifluoromethanesulfonyl)imide anions.

Specific examples of ionic compounds can be selected from the above-mentioned combinations of cationic components and anionic components. Examples of ionic compounds containing organic cations are shown below, categorized by the structure of each organic cation.

Pyridinium salt:

N-Hexylpyridinium hexafluorophosphate,

N-octylpyridinium hexafluorophosphate,

N-octyl-4-methylpyridinium hexafluorophosphate,

N-Butyl-4-methylpyridinium hexafluorophosphate,

N-decylpyridinium bis(fluorosulfonyl)imide,

N-dodecylpyridinium bis(fluorosulfonyl)imide,

N-tetradecylpyridinium bis(fluorosulfonyl)imide,

N-hexadecylpyridinium bis(fluorosulfonyl)imide,

N-dodecyl-4-methylpyridinium bis(fluorosulfonyl)imide,

N-tetradecyl-4-methylpyridinium bis(fluorosulfonyl)imide,

N-hexadecyl-4-methylpyridinium bis(fluorosulfonyl)imide,

N-Benzyl-2-methylpyridinium bis(fluorosulfonyl)imide,

N-Benzyl-4-methylpyridinium bis(fluorosulfonyl)imide,

N-hexylpyridinium bis(trifluoromethanesulfonyl)imide,

N-octylpyridinium bis(trifluoromethanesulfonyl)imide,

N-octyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide,

N-Butyl-4-methylpyridinium bis(trifluoromethanesulfonyl)imide.

Imidazolium salt:

1-Ethyl-3-methylimidazolium hexafluorophosphate,

1-Ethyl-3-methylimidazolium p-toluenesulfonate,

1-Ethyl-3-methylimidazolium bis(fluorosulfonyl)imide,

1-Ethyl-3-methylimidazolium bis(trifluoromethanesulfonyl)imide,

1-Butyl-3-methylimidazolium methanesulfonate,

1-Butyl-3-methylimidazolium bis(fluorosulfonyl)imide.

Pyrrolidinium salt:

N-Butyl-N-methylpyrrolidinium hexafluorophosphate,

N-Butyl-N-methylpyrrolidinium bis(fluorosulfonyl)imide,

N-Butyl-N-methylpyrrolidinium bis(trifluoromethanesulfonyl)imide.

Grade 4 ammonium salt:

Tetrabutylammonium hexafluorophosphate,

Tetrabutylammonium salt, p-toluenesulfonate,

(2-Hydroxyethyl)trimethylammonium bis(trifluoromethanesulfonyl)imide,

(2-Hydroxyethyl)trimethylammonium dimethyl phosphate.

Examples of ionic compounds containing inorganic cations are shown below.

Lithium bromide,

Lithium iodide,

Lithium tetrafluoroborate,

Lithium hexafluorophosphate,

Lithium isothiocyanate,

Lithium perchlorate,

Lithium trifluoromethanesulfonate,

Lithium bis(fluorosulfonyl)imide,

Lithium bis(trifluoromethanesulfonyl)imide,

Lithium bis(pentafluoroethanesulfonyl)imide,

Lithium trifluoromethanesulfonylmethanide,

Lithium p-toluenesulfonate,

Sodium hexafluorophosphate,

Sodium bis(fluorosulfonyl)imide,

Sodium bis(trifluoromethanesulfonyl)imide,

Sodium p-toluenesulfonate,

Potassium hexafluorophosphate,

Potassium bis(fluorosulfonyl)imide,

Potassium bis(trifluoromethanesulfonyl)imide,

Potassium p-toluenesulfonate.

The ionic compound is preferably solid at room temperature. Solid ionic compounds at room temperature can maintain antistatic properties for a longer period of time compared to liquid ionic compounds at room temperature. From the perspective of long-term stability of antistatic properties, the ionic compound preferably has a melting point of 30°C or higher, preferably 35°C or higher. On the other hand, if the melting point is too high, compatibility with (meth)acrylic resins deteriorates. Therefore, the melting point of the ionic compound is preferably 90°C or lower, more preferably 70°C or lower, and even more preferably below 50°C.

The content of the ionic compound in the adhesive composition is preferably 0.1 to 10 parts by mass, more preferably 0.2 to 10 parts by mass, further preferably 0.2 to 9 parts by mass, and particularly preferably 1 to 8 parts by mass, relative to 100 parts by mass of the (meth)acrylic resin. A content of 0.2 parts by mass or greater of the ionic compound is beneficial for improving antistatic properties, while a content of 8 parts by mass or less is beneficial for improving the impact resistance of the adhesive layer 20. Furthermore, when the ionic compound content in the adhesive composition is 2 parts by mass or more, particularly 3 parts by mass or more, the adhesive layer may be susceptible to peeling of the polarizing plate due to physical impact over time. However, the ionic compound content of the present invention can suppress peeling even at 2 parts by mass or 3 parts by mass or more.

The antistatic agent in the adhesive layer may reduce the adhesion between the adhesive layer of the polarizing plate with the adhesive layer and other optical components over time. For the polarizing plate with the adhesive layer, the reduction in adhesion over time can be suppressed by satisfying the structure of formula (1).

[3-4] Silane compounds

The adhesive composition may further contain a silane compound. This can improve the adhesion between the adhesive layer 20 and optical components such as glass substrates.

Examples of the silane compound include vinyl trimethoxysilane, vinyl triethoxysilane, vinyl tris(2-methoxyethoxy)silane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropylmethyldimethoxysilane, 2-( 3,4-Epoxycyclohexyl)ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloyloxypropyltrimethoxysilane, 3-butyltrimethoxysilane, 3-glycidyloxypropyltrimethoxysilane, 3-glycidyloxypropyltriethoxysilane, 3-glycidyloxypropyldimethoxymethylsilane, 3-glycidyloxypropylethoxydimethylsilane, etc.

Two or more silane compounds can be used.

The silane compound may be a polysiloxane oligomer. If the polysiloxane oligomer is shown in the form of a (monomer) oligomer, for example, the following may be cited.

3-Ethyltrimethoxysilane-tetramethoxysilane copolymer,

3-Ethyltrimethoxysilane-tetraethoxysilane copolymer,

3-Ethyltriethoxysilane-tetramethoxysilane copolymer,

3-Ethyltriethoxysilane-tetraethoxysilane copolymer

Etc. copolymers containing propylene;

Methyltrimethoxysilane-tetramethoxysilane copolymer,

Methyltrimethoxysilane-tetraethoxysilane copolymer,

Methyltriethoxysilane-tetramethoxysilane copolymer,

Methyltriethoxysilane-tetraethoxysilane copolymer

Copolymers containing methyl groups;

3-Glycidyloxypropyltrimethoxysilane-tetramethoxysilane copolymer,

3-Glycidyloxypropyltrimethoxysilane-tetraethoxysilane copolymer,

3-Glycidyloxypropyltriethoxysilane-tetramethoxysilane copolymer,

3-Glycidyloxypropyltriethoxysilane-tetraethoxysilane copolymer,

3-Glycidyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer,

3-Glycidyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer,

3-Glycidyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer,

Copolymers containing 3-glycidyloxypropyl groups, such as 3-glycidyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer;

3-Methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer,

3-Methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer,

3-Methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer,

3-Methacryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer,

3-Methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer,

3-Methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer,

3-Methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer,

3-Methacryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer

Copolymers containing methacryloyloxypropyl;

3-Acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer,

3-Acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer,

3-Acryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer,

3-Acryloyloxypropyltriethoxysilane-tetraethoxysilane copolymer,

3-Acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer,

3-Acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer,

3-Acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer,

3-Acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane copolymer

Copolymers containing acryloxypropyl, etc.;

Vinyltrimethoxysilane-tetramethoxysilane copolymer,

Vinyltrimethoxysilane-tetraethoxysilane copolymer,

Vinyltriethoxysilane-tetramethoxysilane copolymer,

Vinyltriethoxysilane-tetraethoxysilane copolymer,

Vinylmethyldimethoxysilane-tetramethoxysilane copolymer,

Vinylmethyldimethoxysilane-tetraethoxysilane copolymer,

Vinylmethyldiethoxysilane-tetramethoxysilane copolymer,

Vinylmethyldiethoxysilane-tetraethoxysilane copolymer

Etc. copolymers containing vinyl groups;

3-Aminopropyltrimethoxysilane-tetramethoxysilane copolymer,

3-Aminopropyltrimethoxysilane-tetraethoxysilane copolymer,

3-Aminopropyltriethoxysilane-tetramethoxysilane copolymer,

3-Aminopropyltriethoxysilane-tetraethoxysilane copolymer,

3-Aminopropylmethyldimethoxysilane-tetramethoxysilane copolymer,

3-Aminopropylmethyldimethoxysilane-tetraethoxysilane copolymer,

3-Aminopropylmethyldiethoxysilane-tetramethoxysilane copolymer,

3-Aminopropylmethyldiethoxysilane-tetraethoxysilane copolymer

Copolymers containing amino groups, etc.

Most of the silane compounds listed above are liquids. The content of the silane compound in the adhesive composition is typically 0.01 to 10 parts by mass, preferably 0.05 to 5 parts by mass, and more preferably 0.2 to 0.4 parts by mass, per 100 parts by mass of the (meth)acrylic resin. A silane compound content of 0.01 parts by mass or greater improves adhesion between the adhesive layer 20 and optical components such as a glass substrate. Furthermore, a silane compound content of 10 parts by mass or less prevents bleeding of the silane compound from the adhesive layer.

[3-5] Other ingredients

Adhesive compositions may contain additives such as crosslinking catalysts, weathering stabilizers, tackifiers, plasticizers, softeners, dyes, pigments, inorganic fillers, light-scattering microparticles, and resins other than (meth)acrylic resins. Furthermore, UV-curable compounds can be added to the adhesive composition to form an adhesive layer, which can then be cured by UV irradiation, creating a harder adhesive layer.

Examples of crosslinking catalysts include hexamethylenediamine, ethylenediamine, polyethyleneimine, hexamethylenetetramine, diethylenetriamine, triethylenetetramine, isophoronediamine, trimethylenediamine, polyurethane resins, melamine resins, and other amine compounds.

[3-6] Formation of adhesive layer

The adhesive layer 20 is obtained by dissolving or dispersing the components of the adhesive composition described above in a solvent to form a solvent-containing adhesive composition. The adhesive composition is then applied to a substrate film or polarizing plate 10 and dried.

The base film is generally a thermoplastic resin film, a typical example of which is a release-treated spacer film. Examples of spacer films include films made of resins such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, and polyarylate, with the adhesive layer surface treated with silicone or plasma.

For example, an adhesive composition can be directly applied to the release-treated surface of the spacer film to form an adhesive layer. This adhesive layer with the spacer film can then be laminated onto the polarizing plate 10 to obtain a polarizing plate with an adhesive layer attached.

Alternatively, the adhesive composition can be directly coated on the surface of the polarizing plate 10 to form an adhesive layer. A spacer film can be layered outside the adhesive layer as needed to produce a polarizing plate with an adhesive layer.

Before the adhesive layer is applied to the surface of the polarizing plate 10, it is preferred that the bonding surface of the polarizing plate 10 and/or the bonding surface of the adhesive layer be subjected to a surface activation treatment, such as plasma treatment or coma treatment, with coma treatment being more preferred.

Alternatively, an adhesive composition may be applied to the second spacer to form an adhesive layer. An adhesive sheet with a spacer film may be deposited on the formed adhesive layer. The second spacer film may be peeled off from the adhesive sheet, and the adhesive layer with the spacer film may be deposited on the polarizing plate 10. The second spacer film preferably has weaker adhesion to the adhesive layer than the spacer film and is easily peelable.

The thickness of the adhesive layer 20 is preferably 5 μm to 45 μm, more preferably 10 μm to 30 μm, and even more preferably 5 μm to 25 μm. When the thickness of the adhesive layer is within this range, it is advantageous in suppressing a decrease in adhesion over time.

<Image display device>

The image display device shown in Figures 1 to 3 is a laminate of polarizing plates 25, 26, and 27 with an adhesive layer and an image display element 30. Typically, an image display device includes the image display element 30 and the polarizing plates 25, 26, and 27 with an adhesive layer laminated thereon with an adhesive layer 20 interposed therebetween.

Polarizing plates 25, 26, and 27 with adhesive layers according to the present invention can provide an image display device in which the decrease in adhesion over time is suppressed.

The image display element 30 may be a liquid crystal cell, an organic EL display element, or other image display element. The layer of the image display element 30 that contacts the adhesive layer 20 may be, for example, a substrate. Examples of the substrate include a thermoplastic resin film or a glass substrate.

[Example]

The present invention is further described below with reference to examples, but the present invention is not limited to these examples. The amounts and contents expressed in parts and percentages are by mass unless otherwise specified.

<Production Example 1: Preparation of Adhesive Layer>

(1) Preparation of adhesive composition

An adhesive composition containing a (meth)acrylic resin (Mw: 142× ^10⁴ , molecular weight distribution (Mw/Mn): 4.8), a crosslinker, and a silane compound was prepared. Six parts by mass of an antistatic agent per 100 parts by mass of the (meth)acrylic resin were mixed with the adhesive composition. Ethyl acetate was then added to a solids concentration of 28% to prepare a solution of adhesive composition a. Furthermore, ethyl acetate was diluted to a solids concentration of 28% without adding an antistatic agent to the adhesive composition to prepare a solution of adhesive composition b.

The crosslinking agent was "Coronate L" (an ethyl acetate solution of a trihydroxymethylpropane adduct of toluene diisocyanate: solids concentration 75% by mass) purchased from Tosoh Corporation.

The silane compound is "KBM-403" (3-glycidyloxypropyltrimethoxysilane) purchased from Xinyue Chemical Co., Ltd.

The antistatic agent is N-decylpyridinium bis(fluorosulfonyl)imide (molecular weight 545.5).

(2) Preparation of adhesive layer

The adhesive compositions a and b prepared in (1) above were applied to the release-treated surface of a second separator formed of a release-treated polyethylene terephthalate film ["PLR-382190" purchased from LINTEC Co., Ltd.] using an applicator to a thickness of 20 μm after drying, and dried at 100°C for 1 minute to produce adhesive layers a and b.

Next, a spacer film is bonded to the exposed surface of the adhesive layer to create adhesive sheets a and b.

(3) Preparation of hardening resin composition

In terms of solid content, 3,4-epoxyepoxyhexylmethyl 3,4-epoxyepoxyhexane carboxyl ester (trade name: Celloxide 2021P, manufactured by Daicel Chemical Co., Ltd.), which is an aliphatic epoxy compound, was used as 35 parts by mass, and 2-[4-(2,3-epoxypropoxy)phenyl]-2-[4-[1,1-bis[4-([2,3-epoxypropoxy]phenyl]ethyl]phenyl]propane (trade name: TECHMORE The components were mixed to prepare a curable resin composition a, including 15 parts by mass of VG3101L (manufactured by PRINTEC Co., Ltd.), 50 parts by mass of bis(3-ethyl-3-oxocyclobutane methyl) ether (trade name: OXT-221, manufactured by Toagosei Co., Ltd.), 4.5 parts by mass of triaryl calcium hexafluorophosphate propylene carbonate (trade name: CPI-100P, manufactured by San-Apro Co., Ltd.) as a polymerization initiator, and 0.25 parts by mass of a silicone leveling agent (trade name: SH710, manufactured by Dow Corning Toray Co., Ltd.) as a leveling agent.

<Examples, Comparative Examples, Reference Examples>

(Example 1)

A polarizing plate with an adhesive layer having the same structure as the polarizing plate 25 with an adhesive layer shown in Figure 1 was produced. A surface-treated triacetate cellulose film (equivalent to the second protective film) was bonded to one side of a uniaxially stretched polyvinyl alcohol film with iodine adsorbed and aligned thereon. A 20 μm thick triacetate cellulose film (equivalent to the first protective film) was bonded to the other side via an aqueous adhesive. The film was then dried at 80°C for 3 minutes to produce a polarizing plate. The surface-treated triacetate cellulose film used was a 25μm-thick triacetate cellulose film with a 7μm-thick surface treatment layer (acrylic resin hard coat) formed on one side (trade name: 25KCHCN-TC, manufactured by Toppan Printing Co., Ltd.). The polarizer was bonded to the film with the surface opposite the surface with the surface treatment layer facing the polarizer. The adhesive layer (a) exposed by peeling off the second separator of the adhesive sheet (a) was then laminated to the surface of the polarizing plate's first protective film. The film was then aged at a relative humidity of 65% for five days to produce a polarizing plate with an adhesive layer. The 20μm-thick cellulose triacetate film, equivalent to the first protective film, has a water absorption rate of 3.5% to 7.0%, a moisture permeability of 600g/ ^m2· 24h or more, and a volume resistivity of ^1010Ω ·cm to ^104Ω ·cm.

(Example 2)

A polarizing plate with an adhesive layer having the same structure as the polarizing plate 26 with an adhesive layer shown in Figure 2 was produced. A surface-treated triacetate cellulose film (trade name: 25KCHCN-TC, corresponding to the second protective film) was bonded to one side of a uniaxially stretched polyvinyl alcohol film with iodine adsorbed and aligned thereon, using an aqueous adhesive. A curable resin composition a was applied to the other side and cured by ultraviolet irradiation to form a cured resin layer, thereby producing the polarizing plate. The surface of the adhesive layer a, exposed by peeling off the second separator of the adhesive sheet a, was bonded to the surface of the hardened layer of the curable resin composition of the polarizing plate, thereby producing the polarizing plate with an adhesive layer of Example 2.

(Comparative example 1)

A polarizing plate was produced by laminating a 12μm-thick polarizer made of a uniaxially stretched polyvinyl alcohol film oriented with iodine by adsorption to one side with a 32μm-thick cellulose triacetate film (equivalent to the second protective film) via an aqueous adhesive. A 23μm-thick cycloolefin polymer film (equivalent to the first protective film) was also laminated to the other side via an aqueous adhesive. The surface of the first protective film of the polarizing plate, exposed by peeling off the second separator of the adhesive sheet a prepared above, was then laminated to the surface of the adhesive layer a, to produce a polarizing plate with an adhesive layer as in Comparative Example 1. The 23μm-thick cycloolefin polymer film, equivalent to the first protective film, has a water absorption rate of <0.01%, a moisture permeability of <0.01g/ ^m2 ·24h, and a volume resistivity of > ^1016Ω ·cm.

(Reference Example 1)

The surface of the first protective film of the polarizing plate of Comparative Example 1 was bonded to the surface of the adhesive layer (b) exposed by peeling off the second separator of the adhesive sheet (b) prepared above, thereby producing the polarizing plate with an adhesive layer of Reference Example 1.

<Measurement of the resistance change rate △R>

Two rectangular samples (Samples 1 and 2), each 5 cm wide and 5 cm long, were cut from the polarizing plates with adhesive layers in Examples 1 and 2, and Comparative Example 1. Each sample was placed in an environment of 23°C and 55% RH for one hour with a separator film in contact with the surface of the adhesive layer. The separator film was then removed from the surface of the adhesive layer. A high resistivity meter (Hiresta-UP, manufactured by Mitsubishi Chemical Corporation) was placed in contact with the surface of the adhesive layer of each sample. A voltage of 100 V was applied for 30 seconds, and the resistance value (referred to as "resistivity R1") was measured.

Next, each sample was attached to a glass plate (Corning) wiped with ethanol, with the adhesive layer in contact with the glass plate. The samples were then autoclaved (50°C, 0.5 MPa, 20 minutes). The autoclaved samples were then placed in an 85°C oven for 100 hours, followed by an additional 1 hour in an environment of 23°C and 55% RH. The electrode of a high resistivity meter (Hircsta-UP, Mitsubishi Chemical Corporation) was then placed in contact with the adhesive layer of each sample. A voltage of 100 V was applied for 30 seconds, and the resistance value (referred to as "resistivity R2") was measured.

The change rate ΔR[%] of the resistance value of the surface of the adhesive layer opposite to the polarizing plate side after being stored at a temperature of 85°C for about 100 hours was calculated by the following formula (3).

△R=〔(R2-R1)/R1〕×100 (3)

In addition, for the polarizing plates with adhesive layers of Examples 1 and 2 and Comparative Example 1, the average value of R1 of the two samples is set as R1, and the average value of R2 of the two samples is set as R2. These values are used to calculate ΔR using formula (3). This ΔR is set as the ΔR of Examples 1 and 2 and Comparative Example 1. The results are shown in Table 1.

[Table 1]

<Peeling force measurement>

For the polarizing plates with adhesive layers from Examples 1 and 2, and Comparative Example 1, strips 10 cm long and 25 mm wide were cut longitudinally, with the polarizer extending in the longitudinal direction. Each sample was attached to an ethanol-wiped glass plate (Corning Co., Ltd.) with the adhesive layer in contact with the glass plate. The samples were then autoclaved (50°C, 0.5 MPa, 20 minutes). After the autoclaved samples were placed in an 85°C oven for 100 hours, they were removed and mounted in a tensile testing machine (AUTOGRAPH AG-X plus, manufactured by Shimadzu Corporation) in a constant temperature chamber set at 85°C. The peel strength was then measured at 85°C, with the peel angle at 180° and a peel speed of 300 mm/min in the longitudinal direction. The peel strength was calculated as the average value of the peel values over a stable interval. The results are shown in Table 2.

<Drop durability test>

For the polarizing plates with adhesive layers of Examples 1, 2, Comparative Example 1, and Reference Example 1, samples (140 mm long, 70 mm wide) were cut into rectangular shapes with four right angles (hereinafter referred to as "right-angled rectangular shapes") and rectangular shapes with four rounded corners with a curvature radius of 1.0 mm (hereinafter referred to as "rounded rectangular shapes") (140 mm long, 70 mm wide). Figure 6 shows the outer shape of the rectangular samples. For each sample, the second spacer on the surface of the adhesive layer was peeled off, and the adhesive layer was applied to the surface of a glass plate (0.5 mm thick). The samples were then pressed with a load of 50 N for 10 seconds to obtain evaluation samples. The glass plate used here was prepared with a shape 1mm larger than the sample's outer shape and bonded to the sample with a distance of 1mm between the glass plate and the sample's outer shape. Specifically, for rectangular samples, a glass plate (0.5mm thick) measuring 142mm long and 72mm wide with all four corners being square was prepared to evaluate the polarizing plate bonded to the rectangular adhesive layer. For rounded rectangular samples, a glass plate (0.5mm thick) measuring 142mm long and 72mm wide with four corners having a rounded curvature radius of 2.0mm was prepared to evaluate the polarizing plate bonded to the rounded rectangular adhesive layer.

Each evaluation sample was placed in an oven at 85°C for 100 hours, followed by a 23°C, 55% RH environment for 1 hour.

A 160g weight was then attached to the back of the polarizing plate of the evaluation sample (the side opposite the surface bonded to the glass plate). The weighted evaluation sample was then subjected to a free-fall test 60 times from a height of 1.2m at room temperature (approximately 23°C). The direction of the drop was adjusted so that all six sides of the evaluation sample (the upper and lower main surfaces, two longitudinal sides, and two transverse sides) were facing downward in sequence. This pattern of dropping each side once was repeated 10 times.

After each drop, the polarizing plate and the glass plate were visually inspected to confirm whether they were bonded. Between 60 free drops, the polarizing plate and the glass plate were evaluated for any observed separation using the following method. The results are shown in Table 2.

A: No peeling was observed.

B: Peeling was observed.

[Table 2]

1:Polarizer

2: Surface treatment layer

3: Second protective film

4: First protective film

10:Polarizing plate

20: Adhesive layer

25: Polarizing plate with adhesive layer

30: Image display component

Claims (7)

A polarizing plate with an adhesive layer comprises a polarizing plate and an adhesive layer laminated on the polarizing plate, wherein the polarizing plate with an adhesive layer has four sides and four corners, at least one of the four corners is a rounded corner with a radius of curvature of 1.0 mm or more, and the polarizing plate comprises a polarizer layer and a first protective film, wherein the first protective film is a polar resin film, and the first protective film and the polarizing plate are connected to each other. The adhesive layer is in contact with the polarizing plate. The adhesive layer contains an antistatic agent. When the resistance values of the surface of the adhesive layer opposite to the polarizing plate are set to R1 [Ω/□] and R2 [Ω/□] respectively after being stored at a temperature of 85°C for about 100 hours, the change rate ΔR [%] calculated by formula (3) satisfies the relationship between formulas (1) and (2): ΔR = [(R2-R1)/R1] × 100 (3) ΔR ≧ 25 (1) ΔR ≦ 98 (2). The polarizing plate with an adhesive layer as described in claim 1 has a rectangular shape. The polarizing plate with an adhesive layer as described in claim 1 or 2, wherein the polarizing plate comprises a polarizer layer and a curable resin composition curing layer, and the curable resin composition curing layer is in contact with the adhesive layer. An image display device comprises an image display element and a polarizing plate with an adhesive layer as described in any one of claims 1 to 3, wherein the adhesive layer of the polarizing plate with an adhesive layer is in contact with and laminated on the image display element. The image display device of claim 4, wherein the outer shape of the polarizing plate with the adhesive layer is located within the outer shape of the image display element, and the outer portion of the polarizing plate with the adhesive layer that is less than 1.0 mm away from the outer shape of the image display element is longer than the outer portion that exceeds 1.0 mm. An image display device comprises an image display element and a polarizing plate with an adhesive layer as described in claim 1 or 2, wherein the adhesive layer of the polarizing plate with an adhesive layer is in contact with and laminated on the image display element. The image display device of claim 6, wherein the outer shape of the polarizing plate with the adhesive layer is located within the outer shape of the image display element, and the distance between the outer shape of the polarizing plate with the adhesive layer and the outer shape of the image display element at the rounded corner portion is less than 1.0 mm.