WO2023199959A1

WO2023199959A1 - Optical layered body, image display panel and image display device

Info

Publication number: WO2023199959A1
Application number: PCT/JP2023/014938
Authority: WO
Inventors: 寛大小野; 智之木村; 雄祐外山
Original assignee: 日東電工株式会社
Priority date: 2022-04-14
Filing date: 2023-04-12
Publication date: 2023-10-19
Also published as: TW202346094A

Abstract

The optical layered body provided includes a polarizing film and an adhesive sheet. The adhesive sheet includes an organic cationic electroconductive agent. In the optical layered body, |∆b^*| is less than 0.60. The value |∆b^*| is the absolute value of the chromaticity difference ∆b^* with respect to transmitted light between a central section and an end section of the optical layered body, determined by a specific evaluation method using a heating test comprising irradiation with high-intensity light. The optical layered body, despite being provided with an adhesive sheet including an electroconductive agent, is suitable for use in an image display panel which may be combined with a high-intensity backlight.

Description

Optical laminates, image display panels and image display devices

The present invention relates to an optical laminate, an image display panel, and an image display device.

In recent years, image display devices typified by liquid crystal display devices have rapidly become popular. These various image display devices have a laminated structure of, for example, an image display cell such as a liquid crystal cell, and an optical laminate including an optical film such as a polarizing film and an adhesive sheet. Adhesive sheets are mainly used for bonding between optical films included in an optical laminate and for bonding an image display cell and an optical laminate.

Static electricity is generated in an image display device during manufacture, for example, when an optical laminate is bonded to an image display cell via an adhesive sheet, or during use, for example, when a user touches the image display device. If the image display device is charged with this static electricity, problems such as poor display may occur. When using an image display device in an environment where static electricity is particularly likely to occur, for example in an environment where other electronic devices are present such as inside a vehicle, adhesive It is conceivable to incorporate a conductive agent into the agent composition. Patent Document 1 discloses an adhesive composition containing a (meth)acrylic polymer having a specific composition and a conductive agent.

Japanese Patent Application Publication No. 2018-123330

Depending on the type of image display device, a lighting system including a backlight is combined. In recent years, there has been a demand for increasing the luminous intensity of the light emitted from the backlight in order to improve the quality of displayed images and optimize it for various usage environments. However, when an optical laminate that uses an adhesive sheet containing a conductive agent is combined with a high-luminance backlight, it has been found that image quality may deteriorate, which was not seen when combining it with a conventional backlight. .

The present invention is an optical laminate that includes a polarizing film and an adhesive sheet, and is suitable for use in an image display panel that is expected to be combined with a high-intensity backlight, although it is equipped with an adhesive sheet that includes a conductive agent. The purpose of this invention is to provide an optical laminate.

The present invention
An optical laminate including a polarizing film and an adhesive sheet,
The adhesive sheet contains an organic cationic conductive agent,
The optical laminate provides an optical laminate having |Δb ^* | of less than 0.60.
However, |Δb ^* | is the absolute value of the chromaticity difference Δb ^* determined by the following evaluation method.
<Evaluation method>
(1) A test sample was prepared by laminating a glass plate so as to sandwich the adhesive sheet together with the polarizing film on the optical laminate, which was cut into a rectangle of 220 mm x 110 mm with the absorption axis of the polarizing film as the long side. Form.
(2) With the test sample formed above placed on a surface light source, a heating test was conducted at 95° C. for 500 hours while irradiating the entire surface of the test sample with white light with a luminous intensity of 15,000 candela from the surface light source. do.
(3) The test sample after the heating test is irradiated with white light with a luminous intensity of 15,000 candela by the surface light source, and the L ^* a ^* b ^* of the transmitted light of the white light at the center and edges of the test sample is measured. The chromaticities b ^* ₀ and b ^* ₁ in the color system are each measured, and the above Δb ^* is determined by the formula: Δb ^* =b ^* ₁ -b ^* ₀ .

From another aspect, the present invention includes:
An image display panel including the above optical laminate is provided.

From another aspect, the present invention includes:
An image display device including the above image display panel is provided.

According to the present invention, an optical laminate including a polarizing film and an adhesive sheet is used for an image display panel that is expected to be combined with a high-intensity backlight even though it includes an adhesive sheet containing a conductive agent. It is possible to provide an optical laminate suitable for.

FIG. 1 is a cross-sectional view schematically showing an example of the optical laminate of the present invention. FIG. 2 is a cross-sectional view schematically showing an example of the optical laminate of the present invention. FIG. 3 is a cross-sectional view schematically showing an example of the optical laminate of the present invention. FIG. 4 is a cross-sectional view schematically showing an example of the optical laminate of the present invention. FIG. 5 is a cross-sectional view schematically showing an example of the image display panel of the present invention. FIG. 6 is a cross-sectional view schematically showing an example of the image display panel of the present invention. FIG. 7 is a cross-sectional view schematically showing an example of the image display panel of the present invention.

The optical laminate according to the first aspect of the present invention is
An optical laminate including a polarizing film and an adhesive sheet,
The adhesive sheet contains an organic cationic conductive agent,
The optical stack has |Δb ^* | of less than 0.60.
However, |Δb ^* | is the absolute value of the chromaticity difference Δb ^* determined by the following evaluation method.
<Evaluation method>
(1) A test sample was prepared by laminating a glass plate so as to sandwich the adhesive sheet together with the polarizing film on the optical laminate, which was cut into a rectangle of 220 mm x 110 mm with the absorption axis of the polarizing film as the long side. Form.
(2) With the test sample formed above placed on a surface light source, a heating test was conducted at 95° C. for 500 hours while irradiating the entire surface of the test sample with white light with a luminous intensity of 15,000 candela from the surface light source. do.
(3) The test sample after the heating test is irradiated with white light with a luminous intensity of 15,000 candela by the surface light source, and the L ^* a ^* b ^* of the transmitted light of the white light at the center and edges of the test sample is measured. The chromaticities b ^* ₀ and b ^* ₁ in the color system are each measured, and the above Δb ^* is determined by the formula: Δb ^* =b ^* ₁ -b ^* ₀ .

In the second aspect of the present invention, for example, in the optical laminate according to the first aspect, the adhesive sheet has a surface resistivity of 9×10 ¹¹ Ω/□ or less.

In a third aspect of the present invention, for example, in the optical laminate according to the first or second aspect, the adhesive sheet is a sheet formed from an adhesive composition containing a (meth)acrylic polymer as a main component. .

In the fourth aspect of the present invention, for example, in the optical laminate according to the third aspect, the (meth)acrylic polymer has a content of constitutional units derived from a hydroxyl group-containing monomer at a content of 1% by weight or less.

In the fifth aspect of the present invention, for example, in the optical laminate according to the third or fourth aspect, the (meth)acrylic polymer contains 3% by weight or more of structural units derived from a carboxyl group-containing monomer. have at a rate of

In a sixth aspect of the present invention, for example, in the optical laminate according to any one of the first to fifth aspects, the adhesive sheet is a sheet formed from an adhesive composition containing an isocyanate-based crosslinking agent. be.

In the seventh aspect of the present invention, for example, in the optical laminate according to the sixth aspect, the isocyanate crosslinking agent is a non-aromatic ring system.

In the eighth aspect of the present invention, for example, in the optical laminate according to the sixth or seventh aspect, the adhesive composition further contains a peroxide-based crosslinking agent.

The image display panel according to the ninth aspect of the present invention includes:
An optical laminate according to any one of the first to eighth aspects is provided.

The image display device according to the tenth aspect of the present invention includes:
An image display panel according to the ninth aspect is provided.

In the eleventh aspect of the present invention, for example, the image display device according to the tenth aspect further includes a lighting system including a backlight, and the luminous intensity of the light irradiated from the backlight to the image display panel is 15,000 candelas or more.

The present invention will be described in detail below, but the present invention is not limited to the following embodiments. Any modifications can be made without departing from the spirit of the invention.

[Optical laminate]
An example of the optical laminate of this embodiment is shown in FIG. The optical laminate 10 (10A) in FIG. 1 includes an adhesive sheet 1 and a polarizing film 2. Polarizing film 2 usually includes a polarizer. The adhesive sheet 1 and the polarizing film 2 are laminated on each other. The optical laminate 10A can be attached to an object (for example, an image display panel) via the adhesive sheet 1. The optical laminate 10A can be used as an optical film with an adhesive sheet, more specifically, as a polarizing film with an adhesive sheet.

The adhesive sheet 1 contains an organic cationic conductive agent. Further, the optical laminate 10 has |Δb ^* | of less than 0.60. However, |Δb ^* | is the chromaticity difference determined by the following evaluation method, more specifically, the chromaticity observed when white light is transmitted between the center and the end of the optical laminate 10. It is the absolute value of the difference in b ^* (chromaticity difference Δb ^* ). The chromaticity b ^* is b ^* defined in the L ^* a ^* b ^* color system (CIELAB color system).

<Evaluation method> (Δb ^* )
(1) A test sample was obtained by laminating a glass plate so as to sandwich the adhesive sheet 1 together with the polarizing film 2 on an optical laminate 10 cut out into a rectangle of size 220 mm x 110 mm with the absorption axis of the polarizing film 2 as the long side. form. As the glass plate, an alkali-free glass plate that does not substantially contain an alkali component (alkali metal oxide) can be selected. The weight ratio of the alkali component in the alkali-free glass is, for example, 1000 ppm or less, and may be 500 ppm or less. The thickness of the glass plate is, for example, about 0.5 to 1 mm. In the optical laminate 10 in which the adhesive sheet 1 is exposed, the adhesive sheet 1 may be bonded to a glass plate, and in this case, reflection of light at the interface between the optical laminate 10 and the glass plate can be suppressed.
(2) With the formed test sample placed on a surface light source, a heating test is conducted at 95° C. for 500 hours while irradiating the entire test sample with white light with a luminous intensity of 15,000 candela from the surface light source. The test sample can be placed so that the glass plate is in contact with a surface light source. For example, a backlight that can be used in an image display device such as a liquid crystal display device can be selected as the surface light source. The white light to be irradiated is normally light equivalent to CIE standard illuminant D65 (color temperature 6500K). The heating test can be performed, for example, by housing the surface light source and the test sample in a heating furnace that can be maintained at a predetermined temperature.
(3) The test sample after the heating test is irradiated with white light with a luminous intensity of 15,000 candela from the surface light source, and the chromaticity b ^* ( Measure b ^* ₀ at the center and b ^* ₁ at the edges. The chromaticity difference Δb ^* is determined by the formula: Δb ^* =b ^* ₁ −b ^* ₀ . The central part is defined as a circular area with a diameter of 30 mm centered at a position 110 mm in the long side direction and 55 mm in the short side direction from the corner of the rectangular test sample. The edge is defined as a circular area with a diameter of 30 mm centered at a position 30 mm in each of the long and short sides from the corner of the test sample. There are four ends in one test sample. b ^* ₁ can be defined as the average value of the measurements at each end. The white light to be irradiated is as described above. To measure b ^* , a measuring device capable of measuring chromaticity b ^* of the L ^* a ^* b ^* color system (for example, Otsuka Electronics LPF series, LCF series, LCD series, etc.) can be used. Measurements are usually carried out at room temperature (25°C±5°C).

According to the studies of the present inventors, when the adhesive sheet 1 contains an inorganic cationic conductive agent (typically, a conductive agent containing an alkali metal cation), only when combined with a high luminous intensity backlight. There is a tendency for a visible reduction in image quality to occur; the reduction in quality is typically observed as yellowing at the edges of the image; and it is expected to occur inside a vehicle during the summer. It has been found that the above tendency becomes particularly strong when exposed to a high temperature environment. The cause of yellowing is presumed to be a mechanism in which various components contained in the adhesive sheet 1 are denatured by radicals generated by inorganic cations and by heat, light, and oxygen diffused into the interior of the adhesive sheet 1 from the edges. be done. Note that the modification starts with radicals generated from inorganic cations, and other components (e.g., various additives such as polymerization initiators, crosslinking agents, and antioxidants, as well as radicals such as polar groups and polymerizable groups) act on the radicals generated from inorganic cations. Radicals generated due to the involvement of polymers with a chemical structure that can act as a catalyst may also act. According to further studies, the organic cationic conductive agent is suitable for suppressing the generation of radicals and suppressing yellowing of the peripheral portion. Furthermore, in the optical laminate 10, the difference in chromaticity b ^* between the center and the ends after high-intensity light irradiation and heating is suppressed. Therefore, although the optical laminate 10 includes an adhesive sheet containing a conductive agent, it is suitable for use in an image display panel that is expected to be combined with a high-intensity backlight.

|Δb ^* | of the optical laminate 10 is 0.58 or less, 0.55 or less, 0.53 or less, 0.50 or less, 0.48 or less, 0.45 or less, 0.43 or less, 0.40 or less , 0.38 or less, 0.35 or less, 0.33 or less, 0.30 or less, 0.28 or less, 0.25 or less, or even 0.23 or less. The lower limit of |Δb ^* | is, for example, 0.05 or more, and may be 0.10 or more.

(adhesive sheet)
The adhesive sheet 1 has a surface resistivity of, for example, 9×10 ¹¹ Ω/□ or less. The surface resistivity of the adhesive sheet 1 is 5×10 ¹¹ Ω/□ or less, 3×10 ¹¹ Ω/□ or less, 2×10 ¹¹ Ω/□ or less, 1×10 ¹¹ Ω/□ or less, 9×10 ¹⁰ Ω /□ or less, 5×10 ¹⁰ Ω/□ or less, 3×10 ¹⁰ Ω/□ or less, 1×10 ¹⁰ Ω/□ or less, 9×10 ⁹ Ω/□ or less, 5×10 ⁹ Ω/□ or less, 3 It may be less than ×10 ⁹ Ω/□, or even less than 1×10 ⁹ Ω/□. The lower limit of the surface resistivity is, for example, 1×10 ⁶ Ω/□ or more, and may be 1×10 ⁷ Ω/□ or more. The optical laminate 10 in which the surface resistivity of the adhesive sheet 1 is within the above range is suitable for use in an environment where static electricity is likely to occur, for example, inside a vehicle.

<Polymer>
The adhesive sheet 1 is, for example, a sheet formed from an adhesive composition containing a polymer as a main component. Examples of polymers are (meth)acrylic polymers, urethane polymers, silicone polymers and rubber polymers. However, the polymer is not limited to the above examples. The polymer is preferably a (meth)acrylic polymer. In other words, the adhesive sheet 1 may be a sheet formed from the adhesive composition (I) containing the (meth)acrylic polymer (A) as a main component. The main component means the component with the highest content in the composition. The content of the main component is, for example, 50% by weight or more, and may be 60% by weight or more, 70% by weight or more, 75% by weight or more, or even 80% by weight or more. In this specification, the (meth)acrylic polymer refers to a polymer having a structural unit derived from a (meth)acrylic monomer such as (meth)acrylate. The content of structural units derived from (meth)acrylic monomers in the (meth)acrylic polymer is, for example, 40% by weight or more, 50% by weight or more, 60% by weight or more, 70% by weight or more, 80% by weight or more. % or more, 85 weight % or more, 90 weight % or more, or even 95 weight % or more. The (meth)acrylic polymer may consist only of structural units derived from (meth)acrylic monomers. (Meth)acrylic means acrylic and methacrylic. (Meth)acrylate means acrylate and methacrylate.

The (meth)acrylic polymer (A) may have one or more constituent units derived from the following monomer (A1).

An example of the monomer (A1) is a (meth)acrylic monomer having an alkyl group having 1 to 30 carbon atoms in its side chain. The alkyl group may be linear or branched. Examples of (meth)acrylic monomers having an alkyl group in the side chain are methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, isopropyl (meth)acrylate, and n-butyl (meth)acrylate. , s-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, isopentyl (meth)acrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate Acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-octyl (meth)acrylate, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate Acrylate, isodecyl (meth)acrylate, n-dodecyl (meth)acrylate (lauryl (meth)acrylate), n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, hexadecyl (meth)acrylate , heptadecyl (meth)acrylate and octadecyl (meth)acrylate. The content of structural units derived from a (meth)acrylic monomer having an alkyl group having 1 to 30 carbon atoms in the side chain in the (meth)acrylic polymer (A) is, for example, 60% by weight or more, and 65% by weight or more. It may be at least 70% by weight, at least 72% by weight, at least 75% by weight, at least 77% by weight, at least 78% by weight, and even at most 79% by weight. The upper limit of the content is, for example, 99% by weight or less, 97% by weight or less, 95% by weight or less, 92% by weight or less, 90% by weight or less, 87% by weight or less, 85% by weight or less, and even 82% by weight. It may be the following.

Another example of the monomer (A1) is a hydroxyl group-containing monomer. The hydroxyl group-containing monomer may be a hydroxyl group-containing (meth)acrylic monomer. Examples of hydroxyl group-containing monomers include 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 8-hydroxyoctyl ( meth)acrylate, hydroxyalkyl (meth)acrylates such as 10-hydroxydecyl (meth)acrylate and 12-hydroxylauryl (meth)acrylate, and (4-hydroxymethylcyclohexyl)-methyl acrylate. From the viewpoint of improving the durability of the adhesive sheet 1, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferred, and 4-hydroxybutyl (meth)acrylate is more preferred. The (meth)acrylic polymer (A) may have a structural unit derived from a hydroxyl group-containing monomer at a content of 1% by weight or less. The content is less than 1% by weight, 0.9% by weight or less, 0.8% by weight or less, 0.7% by weight or less, 0.6% by weight or less, 0.5% by weight or less, 0.5% by weight less than 0.4% by weight, less than 0.4% by weight, less than 0.3% by weight, less than 0.3% by weight, less than 0.2% by weight, less than 0.2% by weight, less than 0.15% by weight , 0.1% by weight or less, less than 0.1% by weight, or even 0.09% by weight or less. The lower limit of the content is, for example, 0.01% by weight or more, 0.02% by weight or more, 0.03% by weight or more, 0.04% by weight or more, and even 0.05% by weight or more. good. Having the content of the structural unit derived from the hydroxyl group-containing monomer within the above range can contribute to improving the durability of the pressure-sensitive adhesive sheet 1, and can particularly contribute to reducing |Δb ^* |.

Another example of the monomer (A1) is a carboxyl group-containing monomer. The carboxyl group-containing monomer may be a carboxyl group-containing (meth)acrylic monomer. Examples of carboxyl group-containing monomers are (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, itaconic acid, maleic acid, fumaric acid and crotonic acid. From the viewpoint of improving the durability of the adhesive sheet 1, (meth)acrylic acid is preferable. The (meth)acrylic polymer (A) may have a structural unit derived from a carboxyl group-containing monomer at a content of 0.5% by weight or more. The content is 0.7% by weight or more, 1% by weight or more, 1.2% by weight or more, 1.5% by weight or more, 1.7% by weight or more, 2% by weight or more, 2.2% by weight or more, It may be 2.5% by weight or more, 2.7% by weight or more, 3% by weight or more, 3.2% by weight or more, or even 3.4% by weight or more. The upper limit of the content is, for example, 10% by weight or less, and may be 8% by weight or less, 7% by weight or less, 6% by weight or less, or even 5% by weight or less. The content of the structural unit derived from the carboxyl group-containing monomer is within the above range, particularly 3% by weight or more, which can contribute to improving the durability of the adhesive sheet 1 and also reduce |Δb ^* | This can particularly contribute to the reduction.

The monomer (A1) may be an aromatic ring-containing monomer, an amino group-containing monomer, or an amide group-containing monomer. The aromatic ring-containing monomer may be an aromatic ring-containing (meth)acrylic monomer. Examples of aromatic ring-containing monomers are phenyl (meth)acrylate, phenoxyethyl (meth)acrylate, benzyl (meth)acrylate, phenoxydiethylene glycol (meth)acrylate, ethylene oxide-modified nonylphenol (meth)acrylate, and hydroxyethylated β- They are naphthol (meth)acrylate and biphenyl (meth)acrylate. Examples of amino group-containing monomers are N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of amide group-containing monomers include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropylacrylamide, N-methyl(meth)acrylamide, N- Butyl (meth)acrylamide, N-hexyl (meth)acrylamide, N-methylol (meth)acrylamide, N-methylol-N-propane (meth)acrylamide, aminomethyl (meth)acrylamide, aminoethyl (meth)acrylamide, mercaptomethyl Acrylamide monomers such as (meth)acrylamide and mercaptoethyl (meth)acrylamide; N-acryloyl heterocycles such as N-(meth)acryloylmorpholine, N-(meth)acryloylpiperidine and N-(meth)acryloylpyrrolidine and N-vinyl group-containing lactam monomers such as N-vinylpyrrolidone and N-vinyl-ε-caprolactam. The (meth)acrylic polymer (A) does not need to have a structural unit derived from an amino group-containing monomer.

The content of structural units derived from the aromatic ring-containing monomer in the (meth)acrylic polymer (A) is, for example, 20% by weight or less, 19% by weight or less, 18% by weight or less, 17% by weight or less, and may be 16% by weight or less. The lower limit of the content is, for example, 0% by weight or more, 2% by weight or more, 5% by weight or more, 7% by weight or more, 10% by weight or more, 12% by weight or more, and even 15% by weight or more. good.

The content of the structural unit derived from the amide-containing monomer in the (meth)acrylic polymer (A) is, for example, 10% by weight or less, 8% by weight or less, 5% by weight or less, 3% by weight or less, 2% by weight or less. % or less, 1.5% by weight or less, or even 1% by weight or less. The lower limit of the content is, for example, 0% by weight or more, and may be 0.2% by weight or more, 0.5% by weight or more, or even 0.7% by weight or more.

The monomer (A1) may be a polyfunctional monomer. Examples of polyfunctional monomers are hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, neopentyl Glycol di(meth)acrylate, pentaerythritol di(meth)acrylate, pentaerythritol tri(meth)acrylate, dipentaerythritol hexa(meth)acrylate, tetramethylolmethane tri(meth)acrylate, allyl(meth)acrylate, vinyl(meth)acrylate ) polyfunctional acrylates such as acrylates, epoxy acrylates, polyester acrylates and urethane acrylates; and divinylbenzene. The polyfunctional acrylate is preferably 1,6-hexanediol diacrylate or dipentaerythritol hexa(meth)acrylate. The (meth)acrylic polymer (A) does not need to have a structural unit derived from a polyfunctional monomer.

The total content of structural units derived from the amino group-containing monomer and the polyfunctional monomer in the (meth)acrylic polymer (A) is preferably 5% by weight or less, more preferably 3% by weight. The content is preferably 1% by weight or less. When the polymer (A) has the structural unit, the total content may be, for example, 0.01% by weight or more, 0.1% by weight or more, or even 0.5% by weight or more.

Examples of other monomers (A1) include alkoxyalkyl (meth)acrylate monomers such as methoxyethyl (meth)acrylate and ethoxyethyl (meth)acrylate; nitrile group-containing monomers such as (meth)acrylonitrile; Meth)acrylate; Epoxy group-containing monomers such as glycidyl (meth)acrylate and methylglycidyl (meth)acrylate; Sulfonic acid group-containing monomers such as sodium vinylsulfonate; Phosphoric acid group-containing monomer; (meth)acrylic acid esters having alicyclic hydrocarbon groups such as cyclopentyl meth)acrylate, cyclohexyl (meth)acrylate and isobornyl (meth)acrylate; vinyl esters such as vinyl acetate and vinyl propionate; styrene and Aromatic vinyl compounds such as vinyltoluene; olefins or dienes such as ethylene, propylene, butadiene, isoprene and isobutylene; vinyl ethers such as vinyl alkyl ether; and vinyl chloride.

The total content of structural units derived from the other monomers (A1) in the polymer (A) is, for example, 10% by weight or less, 5% by weight or less, 3% by weight or less, and even 1% by weight or less. It is preferable that it is 0% by weight (not having the structural unit).

The polymer (A) can be formed by polymerizing one or more of the above-mentioned monomers by a known method. A monomer and a partial polymer of the monomer may be polymerized. Polymerization can be carried out, for example, by solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. From the viewpoint of being able to form a pressure-sensitive adhesive sheet with excellent optical transparency, solution polymerization and active energy ray polymerization are preferred. It is preferable to carry out the polymerization while avoiding contact between the monomer and/or the partially polymerized product and oxygen. For this purpose, for example, polymerization may be carried out in an atmosphere of an inert gas such as nitrogen, or oxygen may be removed using a resin film or the like. Polymerization in a blocked state can be employed. The polymer (A) to be formed may be a random copolymer, a block copolymer, a graft copolymer, or the like.

The polymerization system forming the polymer (A) may contain one or more types of polymerization initiator. The type of polymerization initiator can be selected depending on the polymerization reaction, and may be, for example, a thermal polymerization initiator or a photopolymerization initiator.

Solvents used in solution polymerization include, for example, esters such as ethyl acetate and n-butyl acetate; aromatic hydrocarbons such as toluene and benzene; aliphatic hydrocarbons such as n-hexane and n-heptane; cyclohexane, Alicyclic hydrocarbons such as methylcyclohexane; ketones such as methyl ethyl ketone and methyl isobutyl ketone. However, the solvent is not limited to the above examples. The solvent may be a mixed solvent of two or more kinds of solvents.

The polymerization initiator used in solution polymerization is, for example, an azo polymerization initiator, a peroxide polymerization initiator, or a redox polymerization initiator. Examples of the peroxide polymerization initiator include dibenzoyl peroxide and t-butyl permaleate. Among these, the azo polymerization initiator disclosed in JP-A No. 2002-69411 is preferred. Examples of the azo polymerization initiator include 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, and 2,2'-azobis(2-methylpropion). acid) dimethyl, 4,4'-azobis-4-cyanovaleric acid. However, the polymerization initiator is not limited to the above examples. The amount of the azo polymerization initiator used is, for example, 0.05 to 0.5 parts by weight, and may be 0.1 to 0.3 parts by weight, based on 100 parts by weight of the total amount of monomers.

The active energy rays used for active energy ray polymerization include, for example, ionizing radiation such as α rays, β rays, γ rays, neutron beams, and electron beams, and ultraviolet rays. The active energy rays are preferably ultraviolet rays. Polymerization by irradiation with ultraviolet light is also called photopolymerization. The polymerization system for active energy ray polymerization typically contains a photopolymerization initiator. The polymerization conditions for active energy polymerization are not limited as long as the polymer (A) is formed.

Examples of photopolymerization initiators include benzoin ether photopolymerization initiators, acetophenone photopolymerization initiators, α-ketol photopolymerization initiators, aromatic sulfonyl chloride photopolymerization initiators, and photoactive oxime photopolymerization initiators. , a benzoin-based photopolymerization initiator, a benzyl-based photopolymerization initiator, a benzophenone-based photopolymerization initiator, a ketal-based photopolymerization initiator, and a thioxanthone-based photopolymerization initiator. However, the photopolymerization initiator is not limited to the above examples.

Examples of benzoin ether photopolymerization initiators include benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-1,2-diphenylethan-1-one, and anisole methyl. It is ether. Examples of acetophenone photopolymerization initiators include 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexylphenylketone, 4-phenoxydichloroacetophenone, and 4-(t-butyl)dichloro. It is acetophenone. Examples of the α-ketol photopolymerization initiator are 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)phenyl]-2-methylpropan-1-one. The aromatic sulfonyl chloride photopolymerization initiator is, for example, 2-naphthalenesulfonyl chloride. The photoactive oxime photopolymerization initiator is, for example, 1-phenyl-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. The benzoin-based photopolymerization initiator is, for example, benzoin. The benzylic photopolymerization initiator is, for example, benzyl. Examples of the benzophenone photopolymerization initiator include benzophenone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxybenzophenone, polyvinylbenzophenone, and α-hydroxycyclohexylphenyl ketone. The ketal photopolymerization initiator is, for example, benzyl dimethyl ketal. Examples of the thioxanthone photopolymerization initiator include thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, 2,4-diisopropylthioxanthone, and dodecylthioxanthone.

The amount of the photopolymerization initiator used is, for example, 0.01 to 1 part by weight, and may be 0.05 to 0.5 part by weight, based on 100 parts by weight of the total amount of monomers.

The weight average molecular weight (Mw) of the polymer (A) is, for example, 1 million to 3 million, preferably 1.8 million to 3 million. When the weight average molecular weight of the polymer (A) is 1 million to 3 million, cracks in the pressure-sensitive adhesive sheet can be suppressed, and an increase in viscosity and occurrence of gelation tend to be suppressed. The weight average molecular weight (Mw) of the polymer in this specification is a value (in terms of polystyrene) based on measurement by GPC (gel permeation chromatography).

The glass transition temperature (Tg) of the polymer (A) is, for example, -50°C or lower, preferably -52°C or lower, and more preferably -55°C or lower. The lower limit of Tg of polymer (A) is, for example, -75°C. The Tg of the polymer (A) is the value obtained by determining the Tg of each monomer forming the constituent units of the polymer (A) when it is made into a homopolymer, and averaging these Tg by considering the content of the constituent units. It is.

The content of the polymer (A) in the adhesive composition (I) is, in terms of solid content, for example, 50% by weight or more, 60% by weight or more, 70% by weight or more, 75% by weight or more, 80% by weight or more, It may be 85% by weight or more, 90% by weight or more, 92% by weight or more, 95% by weight or more, or even 97% by weight or more. The upper limit of the content is, for example, 99% by weight or less, and may be 98% by weight or less, 97% by weight or less, 95% by weight or less, 92% by weight or less, or even 90% by weight or less.

<Conductive agent>
The adhesive sheet 1 contains an organic cationic conductive agent. The adhesive sheet 1 may be a sheet formed from an adhesive composition (I) containing a (meth)acrylic polymer (A) as a main component and further containing an organic cationic conductive agent. The adhesive sheet 1 may contain one or more organic cationic conductive agents.

Examples of organic cationic conductive agents are organic cationic salts. In an organic cation salt, the cation part (cation component) usually has an organic structure. The anion part (anion component) of the organic cation salt may have an organic structure or an inorganic structure. The organic cation salt may be an ionic solid having a melting point of 40°C or higher.

An example of a cation is an organic onium containing an organic group. Examples of onium included in organic onium include nitrogen-containing onium, sulfur-containing onium, and phosphorus-containing onium, and preferably nitrogen-containing onium and sulfur-containing onium. Examples of nitrogen-containing oniums include ammonium cations, piperidinium cations, pyrrolidinium cations, pyridinium cations, cations with a pyrroline skeleton, cations with a pyrrole skeleton, imidazolium cations, tetrahydropyrimidinium cations, and dihydropyrimidinium cations. , pyrazolium cation, and pyrazolinium cation. An example of a sulfur-containing onium is a sulfonium cation. An example of a phosphorus-containing onium is a phosphonium cation. Examples of organic groups included in organic onium are alkyl groups, alkoxyl groups, and alkenyl groups. Specific examples of preferred organic oniums are tetraalkylammonium cations (eg, tributylmethylammonium cations), alkylpiperidinium cations, and alkylpyrrolidinium cations.

Examples of anions are Cl ^- , Br ^- , I ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , BF ₄ ^- , PF ₆ ^- , ClO ₄ ^- , NO ₃ ^- , CH ₃ COO ^- , CF ₃ COO ^- , _CH3SO3- ^, _CF3SO3- _, ⁽ _CF3SO2 ₎ _3C- ^, _AsF6- _, ^SbF6- ^, ^NbF6- ^, _TaF6- _, ( _CN ₎ _2N- _, ^C4F9SO ₃ ^- , C ₃ F ₇ COO ^- , (CF ₃ SO ₂ ) (CF ₃ CO) N ^- , ^- O ₃ S(CF ₂ ) ₃ SO ₃ ^- , and represented by the following general formulas (a) to (d) It is an anion that is
(a) (C _n F _2n+1 SO ₂ ) ₂ N ^- (n is an integer from 1 to 10)
(b) CF ₂ (C _m F _2m SO ₂ ) ₂ N ^- (m is an integer from 1 to 10)
(c) ^- O ₃ S (CF ₂ ) _l SO ₃ ^- (l is an integer from 1 to 10)
(d) (C _p F _2p+1 SO ₂ )N ^- (C _q F _2q+1 SO ₂ ) (p and q are integers from 1 to 10 independently)

Specific examples of organic cationic conductive agents are 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI) and trimethylbutylammonium bis(trifluoromethanesulfonyl)imide.

The amount of the organic cationic conductive agent in the adhesive composition forming the adhesive sheet 1 is, for example, 0.1 part by weight or more based on 100 parts by weight of the polymer such as (meth)acrylic polymer (A). 0.3 parts by weight or more, 0.5 parts by weight or more, 0.7 parts by weight or more, 0.9 parts by weight or more, 1 part by weight or more, 3 parts by weight or more, 5 parts by weight or more, and even 7 parts by weight or more. There may be. The upper limit of the blending amount is, for example, 20 parts by weight or less, 15 parts by weight or less, 12 parts by weight or less, 10 parts by weight or less, 8 parts by weight or less, 5 parts by weight or less, 4 parts by weight, based on 100 parts by weight of the polymer. Below, the amount may be 3 parts by weight or less, 2 parts by weight or less, or even 1.5 parts by weight or less.

<Crosslinking agent>
The adhesive composition (for example, the adhesive composition (I) containing (meth)acrylic polymer (A) as a main component) forming the adhesive sheet 1 may further contain a crosslinking agent.

Examples of crosslinking agents are organic crosslinking agents and polyfunctional metal chelates. Examples of organic crosslinking agents are isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents, and imine crosslinking agents. The organic crosslinking agent and the polyfunctional metal chelate can be used for both solvent-type and active energy ray-curable adhesive compositions. When the adhesive composition is a solvent type, the crosslinking agent is preferably an isocyanate-based crosslinking agent or a peroxide-based crosslinking agent. An isocyanate-based crosslinking agent and a peroxide-based crosslinking agent may be used in combination. The adhesive composition may contain an isocyanate-based crosslinking agent. In other words, the adhesive sheet 1 may be a sheet formed from an adhesive composition (for example, adhesive composition (I)) containing an isocyanate-based crosslinking agent. The adhesive composition may contain a peroxide-based crosslinking agent. The adhesive composition may contain both an isocyanate-based crosslinking agent and a peroxide-based crosslinking agent. In other words, the adhesive sheet 1 is a sheet formed from an adhesive composition (for example, adhesive composition (I)) containing an isocyanate-based crosslinking agent and further containing a peroxide-based crosslinking agent. Good too.

Examples of isocyanate-based crosslinking agents include aromatic isocyanate compounds such as tolylene diisocyanate, chlorphenylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, and polymethylene polyphenylisocyanate; cyclopentylene diisocyanate, cyclohexylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and Alicyclic isocyanate compounds such as isophorone diisocyanate; aliphatic isocyanate compounds such as butylene diisocyanate, tetramethylene diisocyanate and hexamethylene diisocyanate. Isocyanate-based crosslinking agents are compounds obtained by adding the above-mentioned isocyanate compounds to polyhydric alcohol compounds such as trimethylolpropane (adducts); A compound subjected to an addition reaction with a polyol (allophanate compound); a derivative of the above-mentioned isocyanate compound such as an isocyanurate compound may also be used. Specific examples of the derivatives include trimethylolpropane/tolylene diisocyanate trimer adduct (for example, Coronate L, manufactured by Tosoh Corporation), trimethylolpropane/hexamethylene diisocyanate trimer adduct (for example, Coronate HL, manufactured by Tosoh Corporation). ), an isocyanurate of hexamethylene diisocyanate (for example, Coronate HX, manufactured by Tosoh Corporation), and an allophanate body obtained by addition-reacting hexamethylene diisocyanate with an acrylic polyol (for example, Coronate 2770, manufactured by Tosoh Corporation).

The isocyanate crosslinking agent may be a non-aromatic ring system. The isocyanate-based crosslinking agent, which is a non-aromatic ring system, can particularly contribute to the reduction of |Δb ^* | in the adhesive sheet 1 formed from the adhesive composition containing the crosslinking agent. In addition, in this specification, "non-aromatic ring system" means a compound that does not contain an aromatic ring. Compounds containing aromatic rings are aromatic ring systems. Examples of the non-aromatic ring isocyanate crosslinking agent are alicyclic isocyanate compounds, aliphatic isocyanate compounds, and derivatives thereof. The non-aromatic isocyanate crosslinking agent may be an aliphatic isocyanate compound or a derivative thereof, or a hexamethylene diisocyanate (HDI) compound or a derivative thereof.

When the adhesive composition forming the adhesive sheet 1 contains an isocyanate-based crosslinking agent, the amount thereof is, for example, 0.1 to 10 parts by weight, and 0.2 to 5 parts by weight, based on 100 parts by weight of the polymer. , 0.25 to 3 parts by weight, 0.3 to 1 part by weight, or even 0.3 to 0.6 parts by weight.

Examples of peroxide-based crosslinking agents include di(2-ethylhexyl)peroxydicarbonate, di(4-t-butylcyclohexyl)peroxydicarbonate, di-sec-butylperoxydicarbonate, t-butylperoxy Neodecanoate, t-hexyl peroxy pivalate, t-butyl peroxy pivalate, dilauroyl peroxide, di-n-octanoyl peroxide, 1,1,3,3-tetramethylbutylperoxy-2 -ethylhexanoate, di(4-methylbenzoyl) peroxide, benzoyl peroxide, t-butylperoxyisobutyrate, and 1,1-di(t-hexylperoxy)cyclohexane. The peroxide-based crosslinking agent may be benzoyl peroxide (BPO) because it has excellent crosslinking reaction efficiency.

When the adhesive composition forming the adhesive sheet 1 contains a peroxide-based crosslinking agent, the amount thereof is, for example, 0.005 to 5 parts by weight, and 0.01 to 3 parts by weight, based on 100 parts by weight of the polymer. parts by weight, 0.05 to 2 parts by weight, 0.07 to 1 part by weight, 0.07 to 0.5 parts by weight, 0.07 to 0.3 parts by weight, and even 0.07 to 0.25 parts by weight. It may be.

<Additives>
The adhesive composition (for example, the adhesive composition (I) containing (meth)acrylic polymer (A) as a main component) forming the adhesive sheet 1 may further contain materials other than those described above. Examples of such materials are additives. Examples of additives include silane coupling agents, antioxidants, colorants such as pigments and dyes, ultraviolet absorbers, surfactants, plasticizers, tackifiers, surface lubricants, leveling agents, rework improvers, They are powders, particles, and foil-like materials such as softeners, polymerization inhibitors, rust preventives, inorganic fillers, organic fillers, and metal powders. The additives can be added in a total amount of, for example, 10 parts by weight or less, preferably 5 parts by weight or less, more preferably 3 parts by weight or less, based on 100 parts by weight of the polymer.

Examples of silane coupling agents are 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldiethoxysilane, 2-(3,4-epoxycyclohexyl)ethyl Epoxy group-containing silane coupling agents such as trimethoxysilane; 3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3 Silane coupling agents containing amino groups such as -dimethylbutylidene)propylamine, N-phenyl-γ-aminopropyltrimethoxysilane; ) Acrylic group-containing silane coupling agent; isocyanate group-containing silane coupling agent such as 3-isocyanatepropyltriethoxysilane.

When the adhesive composition forming the adhesive sheet 1 contains a silane coupling agent, the amount thereof is, for example, 5 parts by weight or less, 3 parts by weight or less, 1 part by weight or less, based on 100 parts by weight of the polymer. The amount may be 0.5 part by weight or less, 0.2 part by weight or less, 0.1 part by weight or less, or even 0.05 part by weight or less. The adhesive composition may not contain a silane coupling agent.

The type of the adhesive composition forming the adhesive sheet 1 is, for example, an emulsion type, a solvent type (solution type), an active energy ray curing type (photocuring type), or a heat melt type (hot melt type). From the viewpoint of being able to form a pressure-sensitive adhesive sheet 1 with excellent durability, the pressure-sensitive adhesive composition may be a solvent type or an active energy ray-curable type, or may be a solvent type. The solvent-based adhesive composition does not need to contain a photocuring agent such as an ultraviolet curing agent.

The adhesive sheet 1 can be formed from an adhesive composition by the following method. For the solvent type, for example, an adhesive composition or a mixture of an adhesive composition and a solvent is applied to a base film to form a coating film, and the formed coating film is dried to form the adhesive sheet 1. . The pressure-sensitive adhesive composition is thermally cured by the heat generated during drying. For the active energy ray-curable type (photocurable type), for example, monomer(s) that becomes a predetermined polymer by polymerization, and if necessary, a partial polymer of the monomer(s), a polymerization initiator, A mixture of additives, a solvent, etc. is applied to a base film, and the formed coating film is irradiated with active energy rays to form the adhesive sheet 1. Before irradiation with active energy rays, the coating film may be dried to remove the solvent. The base film may be a film (release liner) whose coated surface has been subjected to a release treatment.

The adhesive sheet 1 formed on the base film can be transferred to any layer. Moreover, the polarizing film 2 may be sufficient as a base film, and in this case, the optical laminated body 10 containing the adhesive sheet 1 and the polarizing film 2 is obtained.

A known method can be used for coating the base film. Applications include, for example, roll coating, kiss roll coating, gravure coating, reverse coating, roll brushing, spray coating, dip roll coating, bar coating, knife coating, air knife coating, curtain coating, lip coating, extrusion coating using a die coater, etc. It can be implemented by

For the solvent type, the drying temperature after coating is, for example, 40 to 200°C. The drying time may be, for example, 5 seconds to 20 minutes, 5 seconds to 10 minutes, or even 10 seconds to 5 minutes. For the active energy ray-curable type, the drying temperature and drying time when drying after application may be within the above ranges.

It is preferable that the composition and mixture applied to the base film have a viscosity suitable for handling and application. For this reason, for the active energy ray-curable type, the mixture to be applied preferably contains a partial polymer of the monomer(s).

The thickness of the adhesive sheet 1 is, for example, 2 μm to 55 μm, and may be 2 μm to 30 μm, 5 μm to 25 μm, or even 10 μm to 20 μm.

(polarizing film)
The polarizing film 2 is typically a laminate including a polarizer and a protective film (transparent protective film). The protective film is placed, for example, in contact with the main surface (the surface with the widest area) of the polarizer. A polarizer may be placed between two protective films.

The polarizer is not particularly limited, and examples include hydrophilic polymer films such as polyvinyl alcohol films, partially formalized polyvinyl alcohol films, partially saponified ethylene/vinyl acetate copolymer films, iodine, and dichroism. Examples include those obtained by adsorbing dichroic substances such as dyes and uniaxially stretched; polyene-based oriented films such as dehydrated polyvinyl alcohol and dehydrochloric acid treated polyvinyl chloride. A polarizer typically consists of a polyvinyl alcohol film and a dichroic substance such as iodine.

The thickness of the polarizer is not particularly limited, and may be, for example, 80 μm or less, 50 μm or less, 30 μm or less, 25 μm or less, or even 20 μm or less. The lower limit of the thickness of the polarizer is not particularly limited, and may be, for example, 1 μm or more, 5 μm or more, 10 μm or more, or even 15 μm or more. A thin polarizer (for example, 20 μm or less in thickness) has suppressed dimensional changes and can contribute to improving the durability of the optical laminate, especially the durability under high temperatures.

As the material for the protective film, for example, a thermoplastic resin having excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, etc. is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetylcellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins, (meth)acrylic resins, and cyclic resins. Examples include polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material of the protective film may be a thermosetting resin or an ultraviolet curing resin such as (meth)acrylic, urethane, acrylic urethane, epoxy, or silicone. When the polarizing film 2 has two protective films, the materials of the two protective films may be the same or different. For example, a protective film made of a thermoplastic resin is attached to one main surface of a polarizer via an adhesive, and a protective film made of a thermosetting resin or an ultraviolet curable resin is attached to the other main surface of the polarizer. A protective film made of molded resin may be attached. The protective film may contain one or more types of arbitrary additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, color inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, colorants, and the like.

The moisture permeability of the protective film is not particularly limited, and may be 200 g/(m ² ·day) or less, or 50 g/(m ² ·day) or less. In this case, it is possible to suppress moisture in the air from entering the inside of the polarizing film 2, and it is possible to suppress a change in the moisture content of the polarizing film 2. Thereby, it is possible to suppress the occurrence of curling or dimensional changes in the polarizing film 2 during storage or the like. Examples of materials forming the protective film with low moisture permeability include polyester polymers, polycarbonate polymers, arylate polymers, amide polymers, olefin polymers, cyclic olefin polymers, (meth)acrylic polymers, and Mixtures may be mentioned.

The moisture permeability of the protective film can be measured by the following method in accordance with the moisture permeability test (cup method) of JIS Z0208:1976. First, a protective film is cut into a diameter of 60 mm to prepare a measurement sample. Next, the measurement sample is set in a moisture-permeable cup in which approximately 15 g of calcium chloride is placed. This moisture permeable cup is placed in a constant temperature machine set at a temperature of 40° C. and a humidity of 92% RH, and left for 24 hours to conduct a moisture permeability test. By measuring the increase in weight of calcium chloride before and after the test, the moisture permeability of the protective film can be determined.

The thickness of the protective film can be determined as appropriate, but is generally about 10 to 200 μm from the viewpoint of strength, workability such as handleability, thin film property, etc.

A polarizer and a protective film are usually attached to each other via a water-based adhesive or the like. Examples of water-based adhesives include isocyanate adhesives, polyvinyl alcohol adhesives, gelatin adhesives, vinyl latex, water-based polyurethanes, and water-based polyesters. Examples of adhesives other than the above adhesives include ultraviolet curable adhesives and electron beam curable adhesives. Electron beam-curable adhesives for polarizing films exhibit suitable adhesion to various types of protective films. The adhesive may include a metal compound filler.

In the polarizing film, a retardation film or the like can also be formed on the polarizer instead of the protective film. It is also possible to provide another protective film, a retardation film, etc. on the protective film.

Regarding the protective film, a hard coat layer may be provided on the surface opposite to the surface bonded to the polarizer, and treatments for the purpose of anti-reflection, anti-sticking, diffusion, anti-glare, etc. can also be applied. .

The polarizing film 2 is not limited to the above example.

Another example of the optical laminate of this embodiment is shown in FIG. 2. The optical laminate 10 (10B) in FIG. 2 has a laminate structure in which a release liner 3, an adhesive sheet 1, and a polarizing film 2 are laminated in this order. The optical laminate 10B can be used as a polarizing film with an adhesive sheet by peeling off the release liner 3. The following examples may be combined with each other unless technically inconsistent.

Examples of constituent materials of the release liner 3 include polyethylene, polypropylene, polyethylene terephthalate, plastic films such as polyester films, porous materials such as paper, cloth, and nonwoven fabrics, nets, foam sheets, metal foils, and laminates thereof. Examples include suitable thin film materials, but plastic films are preferably used because of their excellent surface smoothness.

The plastic film is not particularly limited as long as it can protect the adhesive sheet 1, and examples thereof include polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film, and vinyl chloride copolymer. film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-vinyl acetate copolymer film, and the like.

The thickness of the release liner 3 is usually about 5 to 200 μm, preferably about 5 to 100 μm. The release liner 3 may be treated with silicone-based, fluorine-based, long-chain alkyl-based or fatty acid amide-based mold release agents, mold release and antifouling treatment with silica powder, coating type, kneading type, vapor deposition, etc., as necessary. Antistatic treatment such as a mold may be applied. In particular, by appropriately performing a release treatment such as silicone treatment, long-chain alkyl treatment, or fluorine treatment on the surface of the release liner 3, the releasability from the pressure-sensitive adhesive sheet 1 can be further improved.

Note that, as described above, the base film used when producing the adhesive sheet 1 may be used as the release liner 3.

Another example of the optical laminate of this embodiment is shown in FIG. The optical laminate 10 (10C) in FIG. 3 has a laminate structure in which a release liner 3, an adhesive sheet 1, a retardation film 5, an interlayer adhesive 4, and a polarizing film 2 are laminated in this order. After peeling off the release liner 3, the optical laminate 10C can be used by being attached to, for example, an image display cell.

As the retardation film 5, one obtained by stretching a polymer film or one obtained by aligning and fixing a liquid crystal material can be used. The retardation film 5 has, for example, birefringence in the plane and/or in the thickness direction.

The retardation film 5 includes a retardation film for antireflection (see JP-A-2012-133303 [0221], [0222], and [0228]) and a retardation film for viewing angle compensation (see JP-A-2012-133303 [0221], [0222], and [0228]). 0225], [0226]), an obliquely oriented retardation film for viewing angle compensation (see JP-A-2012-133303 [0227]), and the like.

The specific configuration of the retardation film 5, for example, retardation value, arrangement angle, three-dimensional birefringence, single layer or multilayer, etc., is not particularly limited, and any known retardation film can be used.

The thickness of the retardation film 5 is preferably 20 μm or less, more preferably 10 μm or less, still more preferably 1 to 9 μm, and particularly preferably 3 to 8 μm.

The retardation film 5 may include, for example, a quarter-wave plate and/or a half-wave plate in which a liquid crystal material is oriented and fixed.

A known adhesive can be used as the interlayer adhesive 4. The adhesive sheet 1 may be used as the interlayer adhesive 4.

Another example of the optical laminate of this embodiment is shown in FIG. 4. The optical laminate 10 (10D) in FIG. 4 has a laminate structure in which a release liner 3, an adhesive sheet 1, a retardation film 5, an interlayer adhesive 4, a polarizing film 2, and a protective film 6 are laminated in this order. After peeling off the release liner 3, the optical laminate 10D can be used by being attached to, for example, an image display cell.

The protective film 6 has the function of protecting the polarizing film 2, which is the outermost layer, during distribution and storage of the optical laminate 10D, and when the optical laminate 10D is incorporated into an image display device. Alternatively, the protective film 6 may function as a window to an external space when incorporated into an image display device. The protective film 6 is typically a resin film. The resin constituting the protective film 6 is, for example, polyester such as PET, polyolefin such as polyethylene and polypropylene, acrylic, cycloolefin, polyimide, and polyamide, with polyester being preferred. However, the protective film 6 is not limited to the above example. The protective film 6 may be a glass film or a laminated film including a glass film. The protective film 6 may be subjected to surface treatments such as anti-glare, anti-reflection, and anti-static.

The protective film 6 may be bonded to the polarizing film 2 with any adhesive. Bonding using the adhesive sheet 1 is also possible.

The optical laminate of this embodiment may include any layers other than those described above.

The optical laminate of this embodiment can be distributed and stored, for example, as a roll of a band-shaped optical laminate or as a sheet-shaped optical laminate. The optical laminate of this embodiment is suitable for use in image display devices, particularly in-vehicle displays, which are used in environments where static electricity is particularly likely to occur. Examples of in-vehicle displays include panels for car navigation devices, cluster panels, mirror displays, and the like. The cluster panel is a panel that displays information such as the vehicle's traveling speed and engine speed.

The optical laminate of this embodiment can be used, for example, in an image display panel and an image display device (for example, a liquid crystal display panel and a liquid crystal display device) equipped with a backlight. However, the use of the optical laminate of this embodiment is not limited to the above example. The present invention is not limited to light from a backlight, and may be used in applications where high intensity light is irradiated.

[Image display panel]
An example of the image display panel of this embodiment is shown in FIG. The image display panel 11A in FIG. 5 includes an optical laminate 10A, and further includes, for example, an image display cell 30A. Specifically, the optical laminate 10A is bonded to the image display cell 30A via the adhesive sheet 1. Note that in place of the optical laminate 10A, the

optical laminate

10B, 10C, or 10D shown in FIGS. 2 to 4 can also be used (excluding the release liner 3).

The image display cell 30A includes, for example, an image forming layer 32, a first transparent substrate 31, and a second transparent substrate 33. The image forming layer 32 is disposed, for example, between the first transparent substrate 31 and the second transparent substrate 33, and is in contact with each of the first transparent substrate 31 and the second transparent substrate 33. The adhesive sheet 1 of the optical laminate 10A is in contact with, for example, the first transparent substrate 31 of the image display cell 30A.

The image forming layer 32 is, for example, a liquid crystal layer containing liquid crystal molecules that are homogeneously aligned in the absence of an electric field. A liquid crystal layer containing such liquid crystal molecules is suitable for an IPS (In-Plane-Switching) method. However, the liquid crystal layer may be of a TN (Twisted Nematic) type, an STN (Super Twisted Nematic) type, a π type, a VA (Vertical Alignment) type, or the like. In this specification, an image display cell provided with a liquid crystal layer may be referred to as a liquid crystal cell, and an image display panel provided with a liquid crystal cell may be referred to as a liquid crystal panel. However, the image forming layer 32 is not limited to a liquid crystal layer, and may be, for example, an EL light emitting layer.

The thickness of the image forming layer 32 is, for example, 1.5 μm to 4 μm.

Examples of materials for the first transparent substrate 31 and the second transparent substrate 33 include glass and polymer. In this specification, a transparent substrate made of a polymer may be referred to as a polymer film. Examples of the polymer constituting the transparent substrate include polyethylene terephthalate, polycycloolefin, polycarbonate, and the like. The thickness of the transparent substrate made of glass is, for example, 0.1 mm to 1 mm. The thickness of the transparent substrate made of polymer is, for example, 10 μm to 200 μm.

The image display cell 30A may further include layers other than the image forming layer 32, the first transparent substrate 31, and the second transparent substrate 33. Examples of other layers include a color filter, an easy-to-adhesion layer, and a hard coat layer. The color filter is arranged, for example, on the viewing side of the image forming layer 32, and is preferably located between the first transparent substrate 31 and the adhesive sheet 1 of the optical laminate 10A. The easily adhesive layer and the hard coat layer are arranged, for example, on the surface of the first transparent substrate 31 or the second transparent substrate 33.

The image display panel 11A may further include members other than the optical laminate 10A and the image display cell 30A. For example, the image display panel 11A may further include a conductive structure (not shown) electrically connected to the side surface of the optical laminate 10A. By connecting the conductive structure to the ground, it is easy to prevent the optical laminate 10A from being charged by static electricity. The conductive structure may cover the entire side surface of the optical laminate 10A, or may partially cover the side surface of the optical laminate 10A. The ratio of the area of the side surface of the optical laminate 10A covered by the conductive structure to the area of the entire side surface of the optical laminate 10A is, for example, 1% or more, preferably 3% or more.

Examples of the material for the conductive structure include conductive paste made of metal such as silver and gold; conductive adhesive; and other conductive materials. The conductive structure may be a wiring extending from the side surface of the optical laminate 10A.

The image display panel 11A may further include an optical film other than the polarizing film 2. Examples of other optical films include films used in image display devices, such as polarizing films, reflective plates, anti-transmissive plates, viewing angle compensation films, and brightness enhancement films. The image display panel 11A may include one or more of these other optical films.

When the other optical film is a polarizing film, the polarizing film is bonded to the second transparent substrate 33 of the image display cell 30A, for example, via an adhesive sheet. This polarizing film has, for example, the configuration described above for the polarizing film 2. In a polarizing film as another optical film, the transmission axis (or absorption axis) of the polarizer is perpendicular to the transmission axis (or absorption axis) of the polarizer in the polarizing film 2, for example. As the material for the adhesive sheet for bonding the polarizing film and the second transparent substrate 33 together, those mentioned above for the adhesive sheet 1 can be used. The thickness of this pressure-sensitive adhesive sheet is not particularly limited, and is, for example, 1 to 100 μm, preferably 2 to 50 μm, more preferably 2 to 40 μm, and still more preferably 5 to 35 μm.

Another example of the image display panel of this embodiment is shown in FIG. The image display panel 11B in FIG. 6 further includes a conductive layer 40 disposed between the optical laminate 10A and the image display cell 30A.

The conductive layer 40 is, for example, a layer containing a conductive agent. As the conductive agent, those mentioned above for the adhesive sheet 1 can be used. However, the conductive agent is not limited to the above example. The conductive layer 40 is made of various conductive agents, such as inorganic cationic conductive agents, carbon nanotubes, ITO, ATO, and conductive polymers that are composites with dopants (for example, poly(3,4-ethylenedioxythiophene)). A complex with polystyrene sulfonic acid: PEDOT/PSS). The thickness of the conductive layer 40 is, for example, 5 nm to 180 nm. The surface resistivity of the conductive layer 40 is, for example, 1.0×10 ⁶ Ω/□ to 1.0×10 ¹⁰ Ω/□, preferably 1.0×10 ⁸ Ω/□ to 1.0×10 ⁹ Ω/□.

Another example of the image display panel of this embodiment is shown in FIG. The image display panel 11C in FIG. 7 includes an image display cell 30B that further includes a touch sensing electrode section 35. In the image display cell 30B, the touch sensing electrode section 35 is arranged between the first transparent substrate 31 and the second transparent substrate 33. The touch sensing electrode section 35 has a touch sensor and touch drive function. The image display panel 11C is a so-called in-cell type image display panel, and the image display cell 30B is a so-called in-cell type image display cell.

The touch sensing electrode section 35 includes, for example, a touch sensor electrode 36 and a touch drive electrode 37. The touch sensor electrode 36 means a (receiving) electrode for touch detection. The touch sensor electrode 36 and the touch drive electrode 37 can be independently formed in various patterns. For example, when the image display cell 30B has a flat plate shape, the touch sensor electrode 36 and the touch drive electrode 37 may be provided independently in the X-axis direction and the Y-axis direction, respectively, and formed in a pattern such that these electrodes intersect at right angles. I can do it. In FIG. 7 , in the touch sensing electrode section 35 , the touch sensor electrode 36 is arranged closer to the viewing side than the touch drive electrode 37 . However, the touch drive electrode 37 may be arranged closer to the viewing side than the touch sensor electrode 36. In the touch sensing electrode section 35, the touch sensor electrode 36 and the touch drive electrode 37 may be integrated.

In FIG. 7, the touch sensing electrode section 35 is arranged between the image forming layer 32 and the first transparent substrate 31 (on the viewing side of the image forming layer 32). However, the touch sensing electrode section 35 may be arranged between the image forming layer 32 and the second transparent substrate 33 (on the side closer to the illumination system than the image forming layer 32).

In the touch sensing electrode section 35, the touch sensor electrode 36 and the touch drive electrode 37 do not need to be in contact with each other. For example, the touch sensor electrode 36 may be arranged between the image forming layer 32 and the first transparent substrate 31, and the touch drive electrode 37 may be arranged between the image forming layer 32 and the second transparent substrate 33.

The drive electrode (the touch drive electrode 37 or the electrode in which the touch sensor electrode 36 and the touch drive electrode 37 are integrated) in the touch sensing electrode section 35 can also serve as a common electrode for controlling the image forming layer 32.

The touch sensor electrode 36 (capacitance sensor), the touch drive electrode 37, or an electrode formed by integrating these, which constitutes the touch sensing electrode section 35, functions as a transparent conductive layer. The material of this transparent conductive layer is not particularly limited, and examples thereof include metals such as gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, titanium, iron, cobalt, tin, magnesium, and tungsten; Examples include alloys. The material of the transparent conductive layer may be an oxide of a metal such as indium, tin, zinc, gallium, antimony, zirconium, or cadmium. Specific examples of this oxide include indium oxide, tin oxide, titanium oxide, cadmium oxide, and mixtures thereof. The material of the transparent conductive layer may be a metal compound such as copper iodide. The material of the transparent conductive layer is preferably indium oxide (ITO) containing tin oxide, tin oxide (ATO) containing antimony, etc., and ITO is particularly preferable. When the material of the transparent conductive layer is ITO, the content of indium oxide in the transparent conductive layer is preferably 80 to 99% by weight, and the content of tin oxide is preferably 1 to 20% by weight.

The electrodes (touch sensor electrode 36, touch drive electrode 37, or an electrode formed by integrating these) constituting the touch sensing electrode section 35 are always placed between the first transparent substrate 31 and the second transparent substrate 33. It can be formed as a transparent electrode pattern by the method. This transparent electrode pattern is electrically connected, for example, to a lead-out line formed at the end of the transparent substrate. The routing line is connected to, for example, a controller IC. The shape of the transparent electrode pattern can be any shape depending on the purpose, such as a comb shape, a stripe shape, or a rhombus shape. The thickness of the transparent electrode pattern is, for example, 10 nm to 100 nm. The width of the transparent electrode pattern is, for example, 0.1 mm to 5 mm.

[Image display device]
The image display device of this embodiment includes, for example, an image display panel 11A and a lighting system. Note that, instead of the image display panel 11A, the image display panels 11B and 11C shown in FIGS. 6 to 7 can also be used. In the image display device, the image display panel 11A is arranged, for example, on the viewing side rather than the illumination system. The illumination system includes, for example, a backlight or a reflector, and irradiates the image display panel 11A with light. The luminous intensity of the backlight irradiation light to the image display panel 11A may be 15,000 candela or more, 16,000 candela or more, 17,000 candela or more, 18,000 candela or more, 19,000 candela or more, or even 20,000 candela or more.

The image display device is, for example, a liquid crystal display. However, the image display device is not limited to the above example. The image display device may be an electroluminescence (EL) display, a plasma display (PD), a field emission display (FED), or the like. The image display device can be used for household appliances, vehicle-mounted applications, public information displays (PID), etc., and may be a vehicle-mounted display.

Hereinafter, the present invention will be explained in more detail with reference to Examples. The invention is not limited to the examples shown below.

<Weight average molecular weight of (meth)acrylic polymer>
The weight average molecular weight (Mw) of the (meth)acrylic polymer was measured by GPC (gel permeation chromatography).
・Analyzer: Tosoh Corporation, HLC-8120GPC
・Column: Manufactured by Tosoh Corporation, G7000H _XL +GMH _XL +GMH _XL
・Column size: 7.8mmφ each x 30cm total 90cm
・Column temperature: 40℃
・Flow rate: 0.8mL/min
・Injection volume: 100μL
・Eluent: Tetrahydrofuran ・Detector: Differential refractometer (RI)
・Standard sample: polystyrene

[Preparation of (meth)acrylic polymer A1]
In a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas inlet tube, and a condenser, 81.93 parts by weight of n-butyl acrylate (BA), 1.00 parts by weight of acrylic acid (AA), and N-vinylpyrrolidone were added. A monomer mixture containing 1.00 parts by weight of (NVP), 16.00 parts by weight of phenoxyethyl acrylate (PEA), and 0.07 parts by weight of 4-hydroxybutyl acrylate (HBA) was charged. Furthermore, 0.1 part by weight of 2,2'-azobisisobutyronitrile (AIBN; manufactured by Kishida Chemical Co., Ltd.) as a polymerization initiator was added together with 100 parts by weight of ethyl acetate to 100 parts by weight of the monomer mixture. . While stirring the mixture gently, nitrogen gas was introduced into the flask to replace the atmosphere with nitrogen. A solution of (meth)acrylic polymer A1 having a weight average molecular weight (Mw) of 2 million was prepared by carrying out a polymerization reaction for 8 hours while maintaining the liquid temperature in the flask at around 55°C.

[Preparation of (meth)acrylic polymer A2]
(Meth)acrylic polymer A1 except that the monomer mixture charged into the flask was 79.43 parts by weight of BA, 3.50 parts by weight of AA, 1.00 parts by weight of NVP, 16.00 parts by weight of PEA, and 0.07 parts by weight of HBA. A solution of (meth)acrylic polymer A2 having a weight average molecular weight (Mw) of 2 million was prepared in the same manner as in the preparation.

[Preparation of (meth)acrylic polymer A3]
(Meth)acrylic polymer A1 except that the monomer mixture charged into the flask was 79.00 parts by weight of BA, 3.50 parts by weight of AA, 1.00 parts by weight of NVP, 16.00 parts by weight of PEA, and 0.50 parts by weight of HBA. A solution of (meth)acrylic polymer A3 having a weight average molecular weight (Mw) of 1 million was prepared in the same manner as in the preparation.

The monomers and amounts used in the synthesis of each (meth)acrylic polymer are summarized in Table 1 below.

[Preparation of (meth)acrylic adhesive composition]
(Example 1)
For 100 parts by weight of the solid content of the solution of (meth)acrylic polymer A1, 1 part by weight of an isocyanate crosslinking agent (manufactured by Tosoh Corporation, Coronate L; trimethylolpropane tolylene diisocyanate; aromatic ring system), 0.2 By blending part by weight of a peroxide crosslinking agent (benzoyl peroxide; BPO) and 1 part by weight of 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (EMI-FSI) as a conductive agent, A solution of the (meth)acrylic adhesive composition of Example 1 was prepared.

(Examples 2-6, Comparative Examples 1-2)
As shown in Table 2 below, an isocyanate crosslinking agent, a peroxide crosslinking agent (not added in Example 6), and a conductive (not blended in Comparative Example 2) to prepare solutions of the (meth)acrylic adhesive compositions of Examples 2 to 6 and Comparative Examples 1 to 2. However, C/L in Table 2 is Coronate L, and C/2770 is a non-aromatic ring-based isocyanate crosslinking agent (manufactured by Tosoh Corporation, Coronate 2770; allophanate compound obtained by addition reaction of hexamethylene diisocyanate with acrylic polyol). , and LiTFSI is an inorganic cationic conductive agent (lithium bis(trifluoromethanesulfonyl)imide).

[Preparation of adhesive sheet]
A solution of each adhesive composition was applied to one side of a polyethylene terephthalate film (release liner; manufactured by Mitsubishi Chemical Polyester Film Co., Ltd., MRF38) whose surface had been treated with a silicone release agent until the thickness of the adhesive sheet after drying was 20 μm. It was applied like this. The obtained coating film was dried at 155° C. for 1 minute to form an adhesive sheet on the surface of the release liner.

<Measurement of surface resistivity>
The surface resistivity of the produced pressure-sensitive adhesive sheet was measured using Hiresta MCP-HT450 manufactured by Mitsubishi Chemical Analytech under conditions of an applied voltage of 250 V and an application time of 10 seconds. The measurement of surface resistivity was carried out under an environment of a temperature of 25° C.±5° C. and a relative humidity of 50±5%.

[Preparation of optical laminate]
<Preparation of polarizing film>
The polyvinyl alcohol film was stretched up to 3 times between rolls having different speed ratios while being dyed for 1 minute in an iodine solution having a concentration of 0.3% by weight at a temperature of 30°C. Next, it is stretched for 0.5 minutes in an aqueous solution containing boric acid at a concentration of 4% by weight and potassium iodide at a concentration of 10% at a temperature of 60°C until the total stretching ratio becomes 6 times. did. Next, a polarizer with a thickness of 18 μm was prepared by immersing it in an aqueous solution containing potassium iodide at a concentration of 1.5% by weight and washing it for 10 seconds at a temperature of 30°C, and then drying it at 50°C for 4 minutes. Obtained. A 30 μm thick transparent protective film made of a modified acrylic polymer having a lactone ring structure was attached to one side of the polarizer using a polyvinyl alcohol adhesive. Furthermore, a 47 μm thick transparent protective film made of a triacetyl cellulose film (Konica Minolta, KC4UY) with a hard coat layer (HC) was bonded to the other surface of the polarizer using a polyvinyl alcohol adhesive. A polarizing film was produced by heating and drying it for 5 minutes in an oven set at 70°C.

<Preparation of optical laminate>
Next, each of the adhesive sheets of Examples and Comparative Examples formed on the release liner was transferred to the polarizing film produced above to produce an optical laminate (polarizing film with adhesive sheet). Note that the adhesive sheet was transferred onto the surface of the polarizing film on the side of the transparent protective film made of a modified acrylic polymer.

<Yellowing of the periphery>
The coloring of the optical laminate (yellowing of the periphery) when placed under high temperature under high-intensity light irradiation was evaluated by the above-mentioned evaluation method. For the glass plate imitating the front transparent member of the image display panel, alkali-free glass with a thickness of 0.5 mm was used. The glass plate was bonded to the adhesive sheet of the produced optical laminate. The surface light source used was a backlight for a liquid crystal display device having a light emitting region capable of irradiating the entire optical laminate placed on the light source with light equivalent to CIE standard light source D65 at a luminous intensity of 15,000 candela. A heating furnace was used for the heating test. For the measurement of b ^* , LPF-200 manufactured by Otsuka Electronics was used. According to the evaluated value of |Δb ^* |, the degree of yellowing of the peripheral portion was evaluated as follows. In addition, in the reference example, the same evaluation was performed on the optical laminate of comparative example 1, except that the luminous intensity of the irradiation light from the backlight was lowered to 10,000 candela.
A: |Δb ^* | is 0.30 or less B: |Δb ^* | is more than 0.30 and less than 0.45 C: |Δb ^* | is more than 0.45 and less than 0.60 D: |Δb ^* | is 0. Over 60

<Durability (high temperature durability)>
The durability (high temperature durability) of the optical laminate was evaluated by the following method. The produced optical laminate was fixed to the surface of a glass plate (Eagle XG, manufactured by Corning) via the adhesive sheet. Fixation was carried out in an atmosphere of 24° C. and 50% RH. Next, after processing in an autoclave at 50°C and 5 atm (absolute pressure) for 15 minutes, it was left to cool to 24°C to stabilize the bonding of the optical laminate to the glass plate, and then heated at 90°C or It was left in a heated atmosphere at 95°C for 500 hours. After leaving it for a while, return it to the atmosphere at 24°C and 50% RH, and visually check whether the polarizing film has peeled off from the glass plate or if there is any bubbling between the glass plate and the polarizing film. , the durability was evaluated.
A: No changes in appearance such as foaming or peeling are observed.
B: Slight peeling or foaming is observed at the edges, but this is within a range that poses no problem for practical use.
C: Slight continuous peeling or foaming is observed at the edges, but this is within a range that poses no problem for practical use.
D: Significant peeling or foaming was observed at the edges, which was a problem in practice.

<Antistatic property>
The antistatic property of the optical laminate was evaluated by the following method (ESD test). The produced optical laminate was fixed to the surface (viewing side surface) of the image display panel shown in FIG. 7 via the adhesive sheet. Next, the liquid crystal display panel to which the optical laminate was fixed was set on a backlight, and static electricity was emitted at an applied voltage of 15 kV from an electrostatic discharge gun to the surface of the polarizing film, which was the exposed surface on the viewing side. The time from the point of firing until the white areas due to static electricity disappeared was measured, and the antistatic property was evaluated as follows.
A: Disappears within 1 second B: Disappears within more than 1 second and within 10 seconds C: Disappears within more than 10 seconds and within 60 seconds D: Disappears after more than 60 seconds

The evaluation results of each optical laminate of Examples and Comparative Examples are shown in Table 3 below, along with the surface resistivity of the adhesive sheet included in each optical laminate.

As shown in Table 3, the optical laminate of the example has better antistatic properties than the optical laminate of the comparative example, but yellowing of the periphery when combined with a high-intensity backlight is reduced. It was suppressed.

The optical laminate of the present invention can be used, for example, in image display devices such as liquid crystal displays.

Claims

An optical laminate including a polarizing film and an adhesive sheet,
The adhesive sheet contains an organic cationic conductive agent,
The optical laminate has a |Δb * | of less than 0.60.
However, |Δb * | is the absolute value of the chromaticity difference Δb * determined by the following evaluation method.
<Evaluation method>
(1) A test sample was prepared by laminating a glass plate so as to sandwich the adhesive sheet together with the polarizing film on the optical laminate, which was cut into a rectangle of 220 mm x 110 mm with the absorption axis of the polarizing film as the long side. Form.
(2) With the test sample formed above placed on a surface light source, a heating test was conducted at 95° C. for 500 hours while irradiating the entire surface of the test sample with white light with a luminous intensity of 15,000 candela from the surface light source. do.
(3) The test sample after the heating test is irradiated with white light with a luminous intensity of 15,000 candela by the surface light source, and the L * a * b * of the transmitted light of the white light at the center and edges of the test sample is measured. The chromaticities b * 0 and b * 1 in the color system are each measured, and the above Δb * is determined by the formula: Δb * =b * 1 -b * 0 .
The optical laminate according to claim 1, wherein the adhesive sheet has a surface resistivity of 9×10 11 Ω/□ or less.
The optical laminate according to claim 1, wherein the adhesive sheet is a sheet formed from an adhesive composition containing a (meth)acrylic polymer as a main component.
The optical laminate according to claim 3, wherein the (meth)acrylic polymer has a structural unit derived from a hydroxyl group-containing monomer at a content of 1% by weight or less.
The optical laminate according to claim 3, wherein the (meth)acrylic polymer has a content of 3% by weight or more of structural units derived from a carboxyl group-containing monomer.
The optical laminate according to claim 1, wherein the adhesive sheet is a sheet formed from an adhesive composition containing an isocyanate-based crosslinking agent.
The optical laminate according to claim 6, wherein the isocyanate-based crosslinking agent is a non-aromatic ring system.
The optical laminate according to claim 6, wherein the adhesive composition further contains a peroxide-based crosslinking agent.
An image display panel comprising the optical laminate according to any one of claims 1 to 8.
An image display device comprising the image display panel according to claim 9.
Further equipped with a lighting system including a backlight,
The image display device according to claim 10, wherein the luminous intensity of the light irradiated from the backlight to the image display panel is 15,000 candela or more.