TW202327885A - Optical multilayer body, image display panel and image display device - Google Patents

Abstract

The present invention provides an optical multilayer body which comprises an adhesive sheet having a sufficiently low surface resistance, and which is suitable for suppression of unwanted coloring of light from an image display device even in cases where the optical multilayer body has been in a high temperature environment. An optical multilayer body 10A according to the present invention comprises: an adhesive sheet 1 that is formed from an adhesive composition containing a polymer (A); and a polarizing plate 2. The polymer (A) has a relative dielectric constant of 5.0 or more at a frequency of 100 kHz. The adhesive sheet 1 has a surface resistance of 1.0 * 1010 [Omega]/□ or less. The haze as measured by the test method described below is 1.0% or less. Test method: A sample for evaluation is formed by sandwiching the optical multilayer body 10A between two alkali-free glass sheets. The haze of the sample for evaluation is measured after heating the sample for evaluation at 105 DEG C for 250 hours.

Description

Optical laminate, image display panel, and image display device

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

In recent years, image display devices represented by liquid crystal display devices and electroluminescent (EL) display devices (such as organic EL display devices and inorganic EL display devices) have been rapidly popularized. These various image display devices have, for example, a laminated structure of an image display unit such as a liquid crystal cell and an EL light-emitting element, and an optical layered body, and the optical layered body includes a polarizing plate and an adhesive sheet. Adhesive sheets are mainly used to join the films contained in the optical laminate or to join the image display unit and the optical laminate.

When an image display device is manufactured, for example, when the optical laminate is bonded to the image display unit through an adhesive sheet, or when it is used, for example, when a user touches the image display device, static electricity is generated. If the image display device is charged by the static electricity, problems such as display failure may occur. Patent Document 1 discloses that a conductive agent (antistatic agent) is added to the adhesive sheet in order to prevent static electricity in the image display device. In Patent Document 1, the surface resistance of the adhesive sheet is adjusted within the range of 1.34×10 ¹⁰ Ω/□ to 4.49×10 ¹⁰ Ω/□. Prior Art Documents Patent Documents

Patent Document 1: Japanese Patent Laid-Open No. 2020-180305

The problem to be solved by the invention According to the research of the inventors of the present invention, when using an image display device in an environment where static electricity is particularly prone to occur (for example, an environment such as inside a vehicle where there are other electronic devices around), in order to fully prevent the display failure of the image display device due to static electricity, The surface resistance value of the adhesive sheet must be adjusted to a lower value. However, according to the research of the inventors of the present invention, if the surface resistance value of the adhesive sheet is adjusted to a lower value, the light from the image display device may cause unnecessary coloring, especially green coloring, under the condition of going through a high temperature environment. Tendency to color.

Therefore, an object of the present invention is to provide an optical laminate comprising an adhesive sheet having a sufficiently low surface resistance and suitable for suppressing unwanted coloration of light from an image display device even when exposed to a high-temperature environment.

Means for Solving the Problems The present invention provides an optical laminate comprising an adhesive sheet and a polarizing plate, and the adhesive sheet is formed of an adhesive composition containing a polymer (A); The relative dielectric constant is 5.0 or more; the surface resistance value of the aforementioned adhesive sheet is 1.0×10 ¹⁰ Ω/□ or less; the haze of the optical laminate measured by the following test method is 1.0% or less. Test method: The aforementioned optical laminate was sandwiched between two sheets of non-alkali glass to prepare a sample for evaluation. After heating the said evaluation sample at 105 degreeC for 250 hours, the haze of this evaluation sample was measured.

Furthermore, the present invention provides an image display panel including the above-mentioned optical layered body.

Furthermore, the present invention provides an image display device including the above-mentioned image display panel.

Invention effect According to the present invention, it is possible to provide an optical laminate comprising an adhesive sheet having a sufficiently low surface resistance value and suitable for suppressing unnecessary coloration of light from an image display device even when exposed to a high-temperature environment.

The present invention will be described in detail below, but the present invention is not limited by the following embodiments, and can be arbitrarily changed and implemented without departing from the gist of the present invention.

[Example of Optical Laminate] An example of the optical layered body of this embodiment is shown in FIG. 1 . The optical laminate 10A in FIG. 1 includes an adhesive sheet 1 and a polarizing plate 2 . The adhesive sheet 1 and the polarizing plate 2 are laminated together. The optical laminate 10A can be bonded to an object (such as an image display panel) through the adhesive sheet 1 . The optical laminate 10A can be used as a polarizing plate with an adhesive sheet attached.

In the optical layered body 10A, the haze H measured by the following test method 1 is 1.0% or less. In addition, when the optical layered body includes a release liner, the following test method 1 is performed after peeling off the release liner. Test method 1: The optical layered body 10A was sandwiched between two sheets of non-alkali glass to prepare a sample for evaluation. After heating the sample for evaluation at 105 degreeC for 250 hours, the haze H of the sample for evaluation was measured.

Hereinafter, Test Method 1 will be described in detail. First, as shown in FIG. 2 , the optical layered body 10A and the alkali-free glass 20A are bonded together through the adhesive sheet 1 . The size of the optical layered body 10A to be used is, for example, 50 mm in length x 50 mm in width. Next, a transparent adhesive sheet 21 made of an optically clear adhesive (OCA: Optical Clear Adhesive) is formed on the surface of the optical laminate 10A opposite to the adhesive sheet 1 , typically on the surface of the polarizing plate 2 . The transparent adhesive sheet 21 is one that can ignore the influence on the haze H value in the test method 1. As a specific example of the adhesive sheet 21, LUCIACS CS98210U manufactured by Nitto Denko Co., Ltd. can be mentioned. Next, the optical layered body 10A and the alkali-free glass 20B are bonded together through the transparent adhesive sheet 21 . Thereby, the evaluation sample 15 in which the optical layered body 10A was sandwiched by the two non-alkali glass 20 was obtained. Moreover, the alkali-free glass 20 is glass which does not contain an alkali component (alkali metal oxide) substantially, Specifically, the weight ratio of the alkali component in glass is 1000 ppm or less, and further is 500 ppm or less. The alkali-free glass 20 is plate-shaped, for example, and has a thickness of 0.5 mm or more. Alkali-free glass 20 is the one that can ignore the influence on the haze H value in test method 1.

Next, after placing the sample 15 for evaluation in a heating environment at 105° C. for 250 hours, the sample 15 for evaluation was naturally cooled to room temperature (for example, 23° C.). About the sample 15 for this evaluation, the haze H was measured according to Japanese Industrial Standard (former Japanese Industrial Standard; JIS) K7136:2000. The haze H can be measured using a commercially available haze meter (for example, HM-150N manufactured by Murakami Color Research Laboratory). When measuring haze H, the light from a light source was made to inject the sample 15 for evaluation from the non-alkali glass 20A side.

The haze H is preferably less than 0.9%, and may be less than 0.8%, less than 0.7%, less than 0.6%, less than 0.5%, less than 0.4%, less than 0.38%, less than 0.35%, and may be less than 0.33%. The optical layered body 10A having a haze H of 1.0% or less is suitable for suppressing unnecessary coloring of light from an image display device even when exposed to a high-temperature environment. The lower limit of the haze H is not particularly limited, and is, for example, 0.1%.

In addition, excluding the case where the sample 15 for evaluation is not placed in a heated environment, the haze _H0 measured by the same method as Test Method 1 is not particularly limited, for example, it is 1.0% or less, and can also be 0.9% or less, 0.8 % or less, 0.7% or less, 0.6% or less, 0.5% or less, 0.4% or less, 0.38% or less, 0.35% or less, and even 0.33% or less. The lower limit of the haze H ₀ is not particularly limited, and is, for example, 0.1%.

In addition, the value (HH ₀ ) obtained by subtracting the haze H ₀ from the haze H is not particularly limited, and is, for example, 0.5% or less, and may be 0.4% or less, 0.3% or less, 0.2% or less, 0.1% or less, or 0.08% less than 0.05%, or less than 0.02%. The lower limit of the value of HH ₀ is, for example, -0.05%.

In this embodiment, the a ^* value and b ^* value in the L ^* a ^* b ^* colorimetric system of the transmitted light measured by the following test method 2 should satisfy the following relational formulas (I) and (II). Test method 2: The optical layered body 10A was sandwiched between two sheets of non-alkali glass to prepare a sample for evaluation. The sample for evaluation was heated at 105° C. for 250 hours. A light source (CIE standard light source D65) was prepared in which an additional polarizing plate forming a relationship of crossed polarization with respect to the absorption axis of the aforementioned polarizing plate 2 in the optical laminate 10A was prepared. Let the light from the light source pass through the additional polarizing plate and enter the surface of the evaluation sample on the side closer to the adhesive sheet 1 than the polarizing plate 2 . Measure the a ^* value and b ^* value in the L ^* a ^* b ^* colorimetric system of the transmitted light of the sample for transmission evaluation. -0.3≦a ^* ≦0.7 (I) -1.5≦b ^* ≦0.5 (II)

Hereinafter, the test method 2 will be described in detail. First, the sample 15 for evaluation was produced by the method similar to test method 1. In the evaluation sample 15 of the test method 2, the size of the optical layered body 10A is, for example, 200 mm in length x 50 mm in width. In sample 15 for evaluation, the transparent adhesive sheet 21 and the non-alkali glass 20 are those which can ignore the influence on the hue of the transmitted light in the use test method 2. Next, after placing the sample 15 for evaluation in a heating environment at 105° C. for 250 hours, the sample 15 for evaluation was naturally cooled to room temperature (for example, 23° C.). Next, as shown in FIG. 3 , a light source 23 (CIE standard light source D65) in which an additional polarizing plate 22 is arranged is prepared. The light source 23 is disposed so as to face the surface of the evaluation sample 15 (the surface of the non-alkali glass 20A) which is on the side closer to the adhesive sheet 1 than the polarizing plate 2 . The additional polarizing plate 22 is disposed between the light source 23 and the evaluation sample 15 so as to form a cross-polarized relationship with respect to the absorption axis of the polarizing plate 2 . Next, the light from the light source 23 is incident on the surface of the non-alkali glass 20A through the added polarizing plate 22 . Specifically, the light from the light source 23 is made incident on the additional polarizing plate 22, and the transmitted light transmitted through the additional polarizing plate 22 is made incident on the surface of the non-alkali glass 20A. For the transmitted light of the sample 15 for transmission evaluation, the spectral transmittance in the wavelength range of 360nm~740nm is specified, and the three stimulus values (X, Y and Z) in the XYZ colorimetric system (CIE1931) are specified from the spectral transmittance ). Tristimulus values are specified in detail in JIS Z8701:1999. Using the obtained tristimulus value, a ^* value and b ^* value were specified by the following formulas (i) and (ii) prescribed in JIS Z8781-4:2013. [mathematical formula 1]

The above-mentioned a ^* value is preferably not less than -0.2 and not more than 0.5, more preferably not less than -0.1 and not more than 0.4. The above b ^* value is preferably not less than -1.2 and not more than 0.3, more preferably not less than -1.0 and not more than 0.1.

(Adhesive Sheet) The adhesive sheet 1 has a surface resistance value R of 1.0×10 ¹⁰ Ω/□ or less. The adhesive sheet 1 having a surface resistance value R as low as this level can prevent display failure of an image display device due to static electricity even in an environment where static electricity is likely to be generated. In addition, the surface resistance value R means the surface resistance value of the adhesive sheet 1 before the humidification process mentioned later is performed. The surface resistance value R is, for example, the surface resistance value immediately after the adhesive sheet 1 is produced.

The surface resistance value R of the adhesive sheet 1 may be 1.0×10 ⁹ Ω/□ or less, 8.0×10 ⁸ Ω/□ or less, 5.0×10 ⁸ Ω/□ or less, 2.0×10 ⁸ Ω/□ or less, 1.0×10 ⁸ Ω/□ or less, 8.0×10 ⁷ Ω/□ or less, 5.0×10 ⁷ Ω/□ or less, and may be 2.0×10 ⁷ Ω/□ or less. The lower limit of the surface resistance value R is not particularly limited, and is, for example, 1.0×10 ⁶ Ω/□ or more, or 1.0×10 ⁷ Ω/□ or more. However, when the optical laminate 10A is used in an image display panel with a built-in touch sensor function, from the viewpoint of suppressing malfunction of the touch sensor, the surface resistance value R is preferably 5.0×10 ⁶ Ω/□ or more , more preferably at least 1.0×10 ⁷ Ω/□. The surface resistance value R of the adhesive sheet 1 can be measured, for example, using a high-resistance resistivity meter (for example, Hiresta series manufactured by Mitsubishi Chemical Analytech), under the conditions of an applied voltage of 250V and an applied time of 10 seconds.

The surface resistance of the adhesive sheet 1 should be small even after experiencing a humid environment. For example, the surface resistance value R ₁ of the adhesive sheet 1 after the humidification treatment by the following test method 3 is, for example, 1.0×10 ¹⁰ Ω/□ or less. In addition, the following test method 3 can also be performed on the optical layered body 10A. Test method 3: Place the adhesive sheet 1 in a humidified environment of 65°C and 95%RH for 250 hours. And the adhesive sheet 1 was arrange|positioned in the environment of 40 degreeC for 1 hour, and it dried.

The surface resistance value _R1 of the adhesive sheet 1 may be, for example, 1.0×10 ⁹ Ω/□ or less, 8.0×10 ⁸ Ω/□ or less, 5.0×10 ⁸ Ω/□ or less, 2.0×10 ⁸ Ω/□ or less, 1.0 ×10 ⁸ Ω/□ or less, 8.0×10 ⁷ Ω/□ or less, 5.0×10 ⁷ Ω/□ or less, and may be 2.0×10 ⁷ Ω/□ or less. The lower limit of the surface resistance value R ₁ is not particularly limited, and is, for example, 1.0×10 ⁶ Ω/□ or more, or 1.0×10 ⁷ Ω/□ or more. However, when the optical laminate 10A is used in an image display panel with a built-in touch sensor function, the surface resistance value R ₁ is preferably 5.0×10 ⁶ Ω/□ from the viewpoint of suppressing malfunction of the touch sensor Above, more preferably 1.0×10 ⁷ Ω/□ or above.

The ratio R 1 /R of the surface resistance value R ₁ (Ω/□) of the adhesive sheet 1 after the humidification treatment to the surface resistance value R (Ω/□) before the humidification treatment is not particularly limited, for example, it is ₁₀ or less, It may be 8 or less, 5 or less, 4 or less, 3 or less, 2 or less, 1.5 or less, 1.4 or less, 1.3 or less, 1.2 or less, and may be 1.1 or less. The lower limit of the ratio R ₁ /R is not particularly limited, and is, for example, 0.95. When the ratio R ₁ /R is 10 or less, the antistatic performance can be suppressed from decreasing over time.

＜Polymer (A)＞ Adhesive sheet 1 is a sheet formed of an adhesive composition (I) containing a polymer (A). The relative permittivity P of the polymer (A) at a frequency of 100 kHz is 5.0 or more. The relative permittivity P can be measured by the following method. First, a test piece with a thickness of 30 µm consisting only of the polymer (A) was produced. For this test piece, the relative permittivity at a frequency of 100 kHz was measured in accordance with JIS K6911:1995. The obtained measured value can be regarded as relative permittivity P. The details of the measurement conditions of the relative permittivity are as follows. ・Measurement conditions Measuring method: capacitance method (device: 4294A Precision Impedance Analyzer manufactured by Agilent Technologies) Electrode composition: Aluminum plate with a diameter of 12.1mm and a thickness of 0.5mm Counter electrode: 3oz copper plate Measurement environment: 23±1℃, 52±1%RH

The relative permittivity P is preferably at least 5.5, and can be at least 6.0, at least 6.5, at least 7.0, at least 7.3, at least 7.4, at least 7.5, at least 7.6, at least 7.7, and can be at least 7.8. The higher the relative permittivity P of the polymer (A), the more likely it is possible to suppress the blending amount of the conductive agent described later and at the same time reduce the surface resistance value of the adhesive sheet 1 . Moreover, the higher the relative permittivity P is, the more the adhesion of the adhesive sheet 1 to the transparent conductive layer such as non-alkali glass or ITO tends to be improved, and the peeling after the durability test is performed tends to be suppressed. The upper limit of the relative permittivity P is not particularly limited, and is 10, for example.

The polymer (A) can be, for example, a (meth)acrylic polymer, a urethane polymer, a silicone polymer, a rubber polymer, etc., and is preferably a (meth)acrylic polymer. The adhesive composition (I) contains, for example, a (meth)acrylic polymer as a main component. In other words, the adhesive composition (I) is an acrylic adhesive composition. The main component means the component with the largest content in the composition. The content rate of the main component is, for example, 50% by weight or more, may be 60% by weight or more, 70% by weight or more, 75% by weight or more, and may be 80% by weight or more. In addition, in this specification, a (meth)acrylic-type polymer means the polymer which has the structural unit derived from the (meth)acrylic-type monomer, such as (meth)acrylate. "(Meth)acryl" means acrylic and methacryl. Moreover, "(meth)acrylate" means acrylate and methacrylate.

The polymer (A) preferably has a structural unit derived from an alkoxy group-containing monomer (A1). The polymer (A) may have one or more structural units derived from the alkoxy group-containing monomer (A1). As an alkoxy group-containing monomer (A1), (meth)acrylate represented by following chemical formula (1) is mentioned, for example. R ¹ in formula (1) is a hydrogen atom or a methyl group. R ² in formula (1) is an alkyl group. The alkyl group may be linear or branched. R ² is preferably a linear alkyl group. Examples of R ² are methyl and ethyl. n in formula (1) is an integer of 1 to 30, preferably an integer of 1 to 5. [chemical formula 1]

Examples of (meth)acrylates represented by formula (1) are: (meth)acrylate 2-methoxyethyl, (meth)acrylate 2-ethoxyethyl, (meth)acrylate 2-(2 - Ethoxyethoxy)ethyl, methoxytriethylene glycol (meth)acrylate and methoxypolyethylene glycol (meth)acrylate, preferably 2-methoxyethyl acrylate (MEA) . Structural units derived from (meth)acrylates of formula (1) can help reduce the surface resistance of the adhesive sheet 1 . Specifically, the structural unit derived from the (meth)acrylate of the formula (1) tends to suppress the compounding amount of the conductive agent described later and reduce the surface resistance value of the adhesive sheet 1 .

In the polymer (A), the content rate of the structural unit derived from the alkoxy group-containing monomer (A1), especially the structural unit derived from the (meth)acrylate of formula (1), is, for example, 15% by weight or more, It can also be more than 20% by weight, more than 30% by weight, more than 40% by weight, more than 50% by weight, more than 60% by weight, more than 70% by weight, more than 80% by weight, more than 90% by weight, and more than 95% by weight . Although the upper limit of the content rate of the structural unit derived from an alkoxy group-containing monomer (A1) is not specifically limited, For example, it is 99 weight%.

The polymer (A) may have a structural unit other than the structural unit derived from the alkoxy group-containing monomer (A1). The structural unit is derived from a monomer (A2) copolymerizable with the alkoxy-containing monomer (A1). The polymer (A) may have 1 type or 2 or more types of this structural unit.

Examples of the monomer (A2) are hydroxyl group-containing monomers. The hydroxyl group-containing monomer may also be a hydroxyl group-containing (meth)acrylic monomer. Examples of hydroxyl-containing monomers are: 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate hydroxyalkyl (meth)acrylate and (4-hydroxy Methylcyclohexyl)-methacrylate. From the viewpoint of improving the durability of the adhesive sheet, 2-hydroxyethyl (meth)acrylate and 4-hydroxybutyl (meth)acrylate are preferable, and 4-hydroxybutyl (meth)acrylate is more preferable. . The content of the structural unit derived from the hydroxyl group-containing monomer in the polymer (A) is, for example, 1% by weight to 5% by weight, may be 3% by weight or less, and may be 2% by weight or less.

Another example of the monomer (A2) is a (meth)acrylic monomer having an alkyl group having 1 to 30 carbon atoms in the 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 Esters, n-butyl (meth)acrylate, secondary butyl (meth)acrylate, tertiary butyl (meth)acrylate, isobutyl (meth)acrylate, n-pentyl (meth)acrylate, ( Isoamyl methacrylate, n-hexyl (meth)acrylate, isohexyl (meth)acrylate, isoheptyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, (meth)acrylic acid n-octyl, isooctyl (meth)acrylate, n-nonyl (meth)acrylate, isononyl (meth)acrylate, n-decyl (meth)acrylate, isodecyl (meth)acrylate, ( n-dodecyl methacrylate (lauryl (meth)acrylate), n-tridecyl (meth)acrylate, n-tetradecyl (meth)acrylate, pentadecyl (meth)acrylate, (meth)acrylate ) cetyl acrylate, heptadecyl (meth)acrylate and stearyl (meth)acrylate. The content of the structural unit derived from the (meth)acrylic monomer having an alkyl group in the polymer (A) is, for example, 80% by weight or less, 70% by weight or less, 60% by weight or less, or 50% by weight. % or less, 40% by weight or less, 30% by weight or less, 20% by weight or less, more preferably 10% by weight or less, or 0% by weight (this structural unit may not be included).

The monomer (A2) may also be an aromatic ring-containing monomer, a carboxyl-containing monomer, an amine-containing monomer, or an amide-containing monomer. The aromatic ring-containing monomer may also 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, oxidized Vinyl modified nonylphenol (meth)acrylate, hydroxyethylated β-naphthol (meth)acrylate and biphenyl (meth)acrylate. 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. Examples of amino group-containing monomers include N,N-dimethylaminoethyl (meth)acrylate and N,N-dimethylaminopropyl (meth)acrylate. Examples of amide-containing monomers are: (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(methyl)acrylamide ) acrylamide, N-methylol-N-propane(meth)acrylamide, aminomethyl(meth)acrylamide, aminoethyl(meth)acrylamide, mercaptomethyl(methyl)acrylamide ) acrylamide and mercaptoethyl (meth)acrylamide and other acrylamide-based monomers; N-acryl heterocyclic monomers such as (meth)acrylpyrrolidine; body.

Monomer (A2) may also be a polyfunctional monomer. Examples of polyfunctional monomers are: hexanediol di(meth)acrylate (1,6-hexanediol di(meth)acrylate), butanediol di(meth)acrylate, (poly) Ethylene Glycol Di(meth)acrylate, (Poly)propylene Glycol Di(meth)acrylate, Neopentyl Glycol Di(meth)acrylate, Neopentyl Glycol Di(meth)acrylate, Neopentyl tetra Alcohol tri(meth)acrylate, Dineopentaerythritol hexa(meth)acrylate, Trimethylolpropane tri(meth)acrylate, Tetramethylolmethane tri(meth)acrylate, (Meth ) polyfunctional acrylates such as allyl acrylate, vinyl (meth)acrylate, epoxy acrylate, polyester acrylate and urethane acrylate; and divinylbenzene. The multifunctional acrylate is preferably 1,6-hexanediol diacrylate and dipenteoerythritol hexa(meth)acrylate.

In the polymer (A), the content rate of the structural unit derived from the aromatic ring-containing monomer is, for example, 3% by weight to 25% by weight, preferably 8% by weight to 24% by weight, more preferably 10% by weight to 22% by weight , more preferably 12% by weight to 18% by weight. The content of the structural unit derived from the aromatic ring-containing monomer varies depending on the case, but may be 10% by weight or less, or may be 8% by weight or less. The polymer (A) may not contain a structural unit derived from an aromatic ring-containing monomer.

The total content of structural units derived from carboxyl group-containing monomers, amine group-containing monomers, amide group-containing monomers, and polyfunctional monomers in the polymer (A) is preferably 20% by weight or less, more preferably 10% by weight. % by weight or less, more preferably 8% by weight or less. When the polymer (A) has this structural unit, the total content is, for example, 0.01% by weight or more, may be 1% by weight or more, 2% by weight or more, and may be 3% by weight or more. The polymer (A) may not contain these structural units. In particular, in the polymer (A), the content of the structural unit derived from the carboxyl group-containing monomer may be less than 0.1% by weight, or may be 0% by weight (the structural unit may not be contained). By making the content of the structural unit derived from the carboxyl group-containing monomer less than 0.1% by weight, even when the adhesive sheet 1 is in contact with a metal oxide such as ITO, the tendency of the metal oxide to corrode can be suppressed. In the case of conventional adhesive sheets, when the content of structural units derived from carboxyl group-containing monomers in the polymer is less than 0.1% by weight, there are conditions above 95°C required in high temperature tests, especially in automotive displays. Under the high temperature test, the adhesive sheet tends to peel off easily. On the other hand, in the adhesive sheet 1 of the present embodiment, by adjusting the relative dielectric constant P of the polymer (A) to 5.0 or more, even structural units derived from carboxyl group-containing monomers in the polymer (A) When the content is less than 0.1% by weight, peeling tends to be suppressed, and high temperature durability and corrosion resistance can be easily balanced.

Examples of other monomers (A2) are: (meth)acrylonitrile and other nitrile-containing (meth)acrylates; glycidyl (meth)acrylate and methylglycidyl (meth)acrylate, etc. Monomers containing epoxy groups; Monomers containing sulfonic acid groups such as sodium vinyl sulfonate; Monomers containing phosphoric acid groups; Cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate and iso(meth)acrylate (meth)acrylates with alicyclic hydrocarbon groups such as camphor; vinyl esters such as vinyl acetate and vinyl propionate; aromatic vinyl compounds such as styrene and vinyl toluene; ethylene, propylene, butadiene, Olefins or dienes such as isoprene and isobutylene; vinyl ethers such as vinyl alkyl ethers; and vinyl chloride.

The total content of the structural units derived from the other monomer (A2) in the polymer (A) is, for example, 30% by weight or less, may be 10% by weight or less, preferably 0% by weight (excluding the structural unit) .

The polymer (A) can be formed by polymerizing one or more monomers described above by a known method. It is also possible to polymerize monomers and partial polymers of monomers. Polymerization can be implemented by, for example, solution polymerization, emulsion polymerization, bulk polymerization, thermal polymerization, or active energy ray polymerization. From the viewpoint of being able to form an adhesive sheet excellent in optical transparency, solution polymerization or active energy ray polymerization is preferable. Polymerization should be carried out by avoiding contact of monomer and/or part of the polymer with oxygen. Therefore, for example, polymerization in an inert gas environment such as nitrogen, or polymerization in a state where oxygen is blocked by a resin film or the like can be used. The formed polymer (A) may be any form of a random copolymer, a block copolymer, a graft copolymer, or the like.

The polymerization system for forming the polymer (A) may also contain one or two or more polymerization initiators. The type of polymerization initiator can be selected according to the polymerization reaction, for example, it can also be a thermal polymerization initiator or a photopolymerization initiator.

Solvents used in solution polymerization are, 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 and methylcyclohexane Alicyclic hydrocarbons such as methyl ethyl ketone, methyl isobutyl ketone and other ketones. However, the solvent is not limited to the above examples. The solvent may be a mixed solvent of two or more solvents.

The polymerization initiator used for the solution polymerization is, for example, an azo-type polymerization initiator, a peroxide-type polymerization initiator, or a redox-type polymerization initiator. Peroxide-based polymerization initiators are, for example, dibenzoyl peroxide and tertiary butyl peroxymaleate. Among them, the azo-based polymerization initiator disclosed in Japanese Patent Application Laid-Open No. 2002-69411 is preferable. The azo-based polymerization initiator is, for example, 2,2'-azobisisobutyronitrile (AIBN), 2,2'-azobis-2-methylbutyronitrile, 2,2'-azobis(2 -dimethylpropionate), 4,4'-azobis-4-cyanovaleric acid. However, the polymerization initiator is not limited to the above examples. The usage-amount of an azo type polymerization initiator is 0.05-0.5 weight part with respect to 100 weight part of total monomers, for example, and may be 0.1-0.3 weight part.

The active energy rays used for active energy ray polymerization are, for example, alpha rays, beta rays, gamma rays, neutron rays, ionizing radiation rays such as electron beams, and ultraviolet rays. The active energy rays are preferably ultraviolet rays. Polymerization by ultraviolet irradiation is also called photopolymerization. The polymerization system of active energy ray polymerization typically includes a photopolymerization initiator. The polymerization conditions of the active energy polymerization are not limited as long as the polymer (A) can be formed.

The photopolymerization initiator is, for example, a benzoin ether photopolymerization initiator, an acetophenone photopolymerization initiator, an α-ketol alcohol photopolymerization initiator, an aromatic sulfonyl chloride photopolymerization initiator, a photoactive oxime Photopolymerization initiator, benzoin photopolymerization initiator, benzyl photopolymerization initiator, benzophenone photopolymerization initiator, ketal photopolymerization initiator, 9-oxosulfur Department of photopolymerization initiator. However, the photopolymerization initiator is not limited to the above examples.

Benzoin ether-based photopolymerization initiators are, for example: benzoin methyl ether, benzoin ethyl ether, benzoin propyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy Base-1,2-diphenylethan-1-one, anisole methyl ether. Acetophenone-based photopolymerization initiators are, for example: 2,2-diethoxyacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 1-hydroxycyclohexyl phenyl ketone, 4 -Phenoxydichloroacetophenone, 4-(tertiary butyl)dichloroacetophenone. The α-ketol-based photopolymerization initiators include, for example, 2-methyl-2-hydroxypropiophenone and 1-[4-(2-hydroxyethyl)benzene]-2-methylpropan-1-one. The aromatic sulfonyl chloride photopolymerization initiator is, for example, 2-naphthalenesulfonyl chloride. The photoactive oxime-based photopolymerization initiator is, for example, 1-benzene-1,1-propanedione-2-(o-ethoxycarbonyl)-oxime. The benzoin-based photopolymerization initiator is, for example, benzoin. The benzyl group photopolymerization initiator is, for example, benzyl group. Benzophenone-based photopolymerization initiators are, for example, diphenylketone, benzoylbenzoic acid, 3,3'-dimethyl-4-methoxydiphenylketone, polyvinyldiphenylketone, α - Hydroxycyclohexyl phenyl ketone. The ketal photopolymerization initiator is, for example, benzyl dimethyl ketal. 9-oxosulfur A photopolymerization initiator such as: 9-oxosulfur 𠮿 , 2-Chloro9-oxosulfur 𠮿 , 2-methyl 9-oxosulfur 𠮿 , 2,4-Dimethyl 9-oxosulfur 𠮿 , Isopropyl 9-oxosulfur , 2,4-Diisopropyl 9-oxosulfur 𠮿 , dodecyl 9-oxosulfur 𠮿 .

The usage-amount of a photoinitiator is 0.01-1 weight part with respect to 100 weight part of total monomers, for example, and may be 0.05-0.5 weight part.

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 adhesive sheet can be suppressed, and the occurrence of viscosity increase or gelation tends to be suppressed. The ratio (Mw/Mn) of the weight average molecular weight Mw of the polymer (A) to the number average molecular weight Mn is, for example, 20 or less, preferably 10 or less, more preferably 7 or less, more preferably 2.5-5. According to the polymer (A) whose Mw/Mn is 20 or less, it is not only easy to adjust the hardness of the adhesive sheet 1 to an appropriate degree, but also suppresses foaming or peeling of the adhesive sheet 1 during a heating test. According to this polymer (A), the processability of the adhesive sheet 1 also tends to be favorable. The weight average molecular weight (Mw) or Mw/Mn of the polymer and oligomer in this specification is the value (polystyrene conversion) measured by GPC (gel permeation chromatography; Gel Permeation Chromatography).

The glass transition temperature (Tg) of the polymer (A) is, for example, -50°C or lower, preferably -52°C or lower, more preferably -55°C or lower. The lower limit of Tg of a polymer (A) is -75 degreeC, for example. The Tg of the polymer (A) is obtained by calculating the Tg of each monomer forming the structural unit of the polymer (A) when it is made into a homopolymer, and taking the content rate of the structural unit into consideration, and averaging these Tg value.

The content of the polymer (A) in the adhesive composition (I) is, in terms of solid content ratio, for example, 50% by weight or more, may be 60% by weight or more, 70% by weight or more, and may be 80% by weight or more . The upper limit of the content rate is, for example, 99% by weight or less, may be 97% by weight or less, 95% by weight or less, 93% by weight or less, and may be 90% by weight or less.

＜Conductive agent＞ The adhesive composition (I) further includes, for example, a conductive agent (antistatic agent). The adhesive composition (I) may have one or more conductive agents. Examples of the conductive agent are ionic compounds such as salts. The ionic compound may also be an ionic liquid that is liquid at normal temperature (25° C.). The melting point of ionic compounds can be lower than 25°C, 25°C~90°C, or higher than 90°C. The melting point of the ionic compound is preferably lower than 25°C or higher than 90°C. When the melting point of the ionic compound is lower than 25°C, the ionic compound will be precipitated to reduce the risk of affecting the appearance. In addition, when the melting point of the ionic compound is higher than 90° C., the ionic compound tends to bleed out from the adhesive sheet 1 less easily.

Examples of ionic compounds include inorganic cation salts and organic cation salts. Inorganic cation salts are in particular inorganic cation-anion salts. The cations contained in the inorganic cation salts include, for example, alkali metal ions. Examples of alkali metal ions include lithium ions, sodium ions, potassium ions, etc., preferably lithium ions. From the viewpoint of reducing the surface resistance value of the adhesive sheet 1, the inorganic cation salt is preferably a lithium salt.

Anions contained in inorganic cationic salts include Cl ^- , Br ^- , I ^- , AlCl ₄ ^- , Al ₂ Cl ₇ ^- , BF ₄ ^- , PF ₆ ^- , ClO ₄ ^- , NO ₃ ^- , CH ₃ COO ^- , CF ₃ COO ^- , CH ₃ SO ₃ ^- , CF ₃ SO ₃ ^- , (CF ₃ SO ₂ ) ₃ C ^- , AsF ₆ ^- , SbF ₆ ^- , NbF ₆ - , TaF ₆ ^{- ,} (CN) ₂ N ^- , C ₄ F ₉ SO ₃ ^- , C ₃ F ₇ COO ^- , (CF ₃ SO ₂ )(CF ₃ CO)N ^- , ^- O ₃ S(CF ₂ ) ₃ SO ₃ ^- and the following general formulas (a)~( d) Anions shown. (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 independently integers from 1 to 10)

The anion contained in the inorganic cationic salt is preferably a fluorine-containing anion, more preferably a fluoride-containing imide anion. The fluorine-containing imide anion includes, for example, an imide anion having a perfluoroalkyl group. The fluorine-containing imide anion can be (CF ₃ SO ₂ )(CF ₃ CO)N ^- , or an anion represented by the above general formula (a), (b) or (d), preferably (CF ₃ SO ₂ ) ₂ N ^- , (C ₂ F ₅ SO ₂ ) ₂ N ^- and other (perfluoroalkylsulfonyl)imides represented by general formula (a), preferably (CF ₃ SO ₂ ) ₂ N ^- The bis(trifluoromethanesulfonyl)imide shown. The ideal inorganic cation salt can be, for example, lithium bis(trifluoromethanesulfonyl)imide (LiTFSI).

Organic cation salts are in particular organic cation-anion salts. The cation contained in the organic cation salt is, for example, an organic onium containing an organic group. The onium contained in the organic onium includes, for example, nitrogen-containing onium, sulfur-containing onium, and phosphonium-containing onium, preferably nitrogen-containing onium and sulfur-containing onium. Examples of nitrogen-containing onium include: ammonium cation, piperidinium cation, pyrrolidinium cation, pyridinium cation, cation having a dihydropyrrole skeleton, cation having a pyrrole skeleton, imidazolium cation, tetrahydropyrimidinium cation, dihydropyrimidine Onium cation, pyrazolium cation, pyrazolinium cation, etc. The sulfur-containing onium can be exemplified by a caldium cation. Phosphonium-containing oniums include, for example, phosphonium cations. The organic group contained in the organic onium includes, for example, an alkyl group, an alkoxy group, and an alkenyl group. Specific examples of ideal organic onium include tetraalkylammonium cations (such as tributylmethylammonium cations), alkylpiperidinium cations, alkylpyrrolidinium cations, and the like.

The anions contained in the organic cation salts may be those mentioned above for the inorganic cations. Desirable organic cation salts include, for example, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide, trimethylbutylammonium bis(trifluoromethanesulfonyl)imide, and the like.

In the adhesive composition (I), an inorganic cation salt and an organic cation salt may be used in combination.

With respect to 100 parts by weight of the polymer (A), the blending amount of the conductive agent is, for example, 0.5 parts by weight or more, may be 1.0 parts by weight or more, 2.0 parts by weight or more, 3.0 parts by weight or more, and may be 4.0 parts by weight or more. With respect to 100 parts by weight of the polymer (A), the blending amount of the conductive agent is, for example, 20 parts by weight or less, or 15 parts by weight or less, 10 parts by weight or less, less than 10 parts by weight, 9.0 parts by weight or less, or 8.0 parts by weight Less than, 7.0 parts by weight or less, 6.0 parts by weight or less, more preferably 5.0 parts by weight or less. With respect to 100 parts by weight of the polymer (A), the blending amount of the conductive agent may be 5.0 parts by weight to 10 parts by weight.

As mentioned above, in this embodiment, the relative dielectric constant P of a polymer (A) is 5.0 or more. The polymer (A) whose relative permittivity P is as high as the above-mentioned degree can promote the release of a conductive agent, especially an ionic compound, and can improve ion conductivity. That is, if the polymer (A) is used, the blending amount of the conductive agent can be suppressed, and the surface resistance value of the adhesive sheet 1 tends to be lowered. In addition, the polymer (A) tends to suppress the precipitation of the conductive agent from the adhesive sheet 1 in a high-temperature environment. If the precipitation of the conductive agent is suppressed in a high-temperature environment, the haze H measured by the above-mentioned test method 1 tends to be reduced, and unnecessary coloring of the light from the image display device tends to be suppressed.

＜Additives＞ The adhesive composition (I) may also contain other additives. Examples of additives are: crosslinking agent, silane coupling agent, colorant such as pigment and dye, ultraviolet absorber, surfactant, plasticizer, tackifier, surface lubricant, leveling agent, heavy industry enhancer, softener , Antioxidants, antiaging agents, light stabilizers, polymerization inhibitors, antirust agents, inorganic fillers, organic fillers, metal powders, etc., powders, particles, and foils. The additive can be blended in a range of, for example, 10 parts by weight or less, preferably 5 parts by weight or less, more preferably 1 part by weight or less, with respect to 100 parts by weight of the polymer (A).

Examples of crosslinking agents are organic crosslinking agents and polyfunctional metal chelate compounds. Examples of organic crosslinking agents are isocyanate crosslinking agents, peroxide crosslinking agents, epoxy crosslinking agents and imine crosslinking agents. Organic cross-linking agents and polyfunctional metal chelates can also be used for any type of adhesive composition of solvent type and active energy ray curing type. When the adhesive composition (I) is solvent-based, the crosslinking agent is preferably a peroxide-based crosslinking agent or an isocyanate-based crosslinking agent. A peroxide-based crosslinking agent and an isocyanate-based crosslinking agent may also be used in combination. The adhesive composition (I) preferably contains a peroxide-based crosslinking agent.

Examples of peroxide-based crosslinking agents include bis(2-ethylhexyl)peroxydicarbonate, bis(4-tertiary butylcyclohexyl)peroxydicarbonate, di-secondary butylperoxydicarbonate, Dicarbonate, tertiary butyl peroxyneodecanoate, tertiary hexyl peroxytrimethylacetate, tertiary butyl peroxytrimethylacetate, dilauroyl peroxide, di-n-octyl peroxide substances, 1,1,3,3-tetramethylbutylperoxy-2-ethylhexanoate, bis(4-methylbenzoyl) peroxide, benzoyl peroxide, Tertiary butylperoxyisobutyrate, 1,1-di(tertiary hexylperoxy)cyclohexane, etc., are preferably benzoyl peroxide in terms of excellent crosslinking reaction efficiency.

Isocyanate-based crosslinking agents include, for example, aromatic isocyanate compounds such as toluene diisocyanate, chlorophenylene diisocyanate, diphenylmethane diisocyanate, xylene diisocyanate, and polymethylene polyphenylisocyanate; Alicyclic isocyanate compounds such as pentyl diisocyanate, cyclohexylene diisocyanate, hydrogenated diphenylmethane diisocyanate and isophorone diisocyanate; butylene diisocyanate, tetramethylene diisocyanate and hexamethylene diisocyanate Aliphatic isocyanate compounds such as isocyanates. The isocyanate-based crosslinking agent can also be: a compound (adduct) obtained by adding the above-mentioned isocyanate compound to a polyol compound such as trimethylolpropane; Polyols, polybutadiene polyols, polyisoprene polyols and other polyols through the addition reaction of polyols; derivatives of the above isocyanate compounds such as isocyanate isocyanate. Specific examples of derivatives include trimethylolpropane/cresyl diisocyanate trimer adducts (such as CORONATE L manufactured by Nippon Polyurethane Industry), trimethylolpropane/hexamethylene diisocyanate trimer adducts (for example, CORONATE HL manufactured by Nippon Polyurethane Industry), trimeric isocyanate body of hexamethylene diisocyanate (for example, CORONATE HX manufactured by Nippon Polyurethane Industry).

When the adhesive composition (I) contains a crosslinking agent, the blending amount of the crosslinking agent is, for example, 0.01 to 10 parts by weight, 0.1 to 5 parts by weight, 0.1 to 3 parts by weight relative to 100 parts by weight of the polymer (A). parts by weight, more preferably 0.1 to 1 part by weight. When the crosslinking agent is too small, foaming may occur in a durability test or processability may deteriorate. When the crosslinking agent is too large, peeling may occur in the durability test, or the surface resistance value may increase and the antistatic property may deteriorate.

Specific examples of silane coupling agents include, for example: 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyl Diethoxysilane, 2-(3-4-epoxycyclohexyl)ethyltrimethoxysilane and other epoxy-containing silane coupling agents; 3-aminopropyltrimethoxysilane, N-2-(amine Ethyl)-3-aminopropylmethyldimethoxysilane, 3-triethoxysilyl-N-(1,3-dimethylbutylene)propylamine, N-phenyl-γ-aminopropyl Amino-containing silane coupling agents such as trimethoxysilane; 3-acryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, etc. silane coupling agent; 3-isocyanate propyltriethoxysilane and other silane coupling agents containing isocyanate groups.

When the adhesive composition (I) contains a silane coupling agent, the blending amount of the silane coupling agent is, for example, not more than 5 parts by weight, or not more than 3 parts by weight, or not more than 1 part by weight relative to 100 parts by weight of the polymer (A). , 0.5 parts by weight or less, 0.2 parts by weight or less, 0.1 parts by weight or less, more preferably 0.05 parts by weight or less.

The type of the adhesive composition (I) is, for example, latex type, solvent type (solution type), active energy ray (photocurable type), heat-melt type (hot-melt type), and the like. From the viewpoint of being able to form the adhesive sheet 1 with excellent durability, the adhesive composition (I) may be a solvent type, an active energy ray curing type, or a solvent type. The solvent-based adhesive composition (I) may not contain photocuring agents such as ultraviolet curing agents.

The adhesive sheet 1 can be produced from the adhesive composition (I) by the following method. Regarding the solvent type, for example, the adhesive composition (I) or a mixture of the adhesive composition (I) and a solvent can be applied to a substrate film to form a coating film, and the formed coating film can be dried to form Adhesive sheet 1. The adhesive composition (I) is thermally cured by heat during drying. Regarding the active energy ray curing type (photocuring type), for example, the following mixture can be coated on a base film, and the formed coating film can be irradiated with active energy rays to form the adhesive sheet 1 . A mixture of the monomer (group) to be the polymer (A), and a partial polymer of the monomer (group) if necessary, a polymerization initiator, an additive, a solvent, and the like. Before irradiating 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 released.

The adhesive sheet 1 formed on the base film can be transferred to any layer. In addition, the base film may be the polarizing plate 2, and in this case, an optical laminate 10A including the adhesive sheet 1 and the polarizing plate 2 can be obtained.

A known method can be used for coating on a base film. Coating can be performed by, for example, roll coating, touch roll coating, gravure coating, reverse coating, roll brush coating, spray coating, dip roll coating, rod coating, knife coat, air knife coating, curtain coating, etc. Coating, lip coating, and extrusion coating using a die coater or the like are performed.

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

Compositions and mixtures applied to substrate films preferably have a viscosity suitable for handling and coating. Therefore, regarding the active energy ray curing type, the coating mixture preferably contains a partial polymer of the monomer (group).

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

The adhesive force of the adhesive sheet 1 to glass is preferably 1.0 N/25mm or higher, more preferably 1.5 N/25 mm or higher, more preferably 2.0 N/25 mm or higher. If the adhesive force is within the above range, the adhesion to the image display panel will be good, and the reworkability will be excellent. The upper limit of the adhesive force is, for example, 6.0 N/25 mm.

In this embodiment, when the cross-section of the adhesive sheet 1 is observed with a transmission electron microscope (TEM), the maximum diameter of the area within the range of 6 µm in length and 6 µm in width is preferably 150 nm or less. In this specification, domain means an island-like phase of a sea-island structure formed in an adhesive sheet. Fields are usually observed as substantially circular island-like regions.

The maximum diameter of the field can be specified by the following method. First, the adhesive sheet 1 is cut, and the cross section is observed with TEM. The magnification at this time is, for example, 20,000 times. In the TEM image, a domain within a range of 6 µm in length and 6 µm in width was identified. For each specific field, specify the length of the exit diameter (the diameter of the smallest circle that can enclose the field). Among the specified out-of-path lengths, the maximum value can be regarded as the maximum diameter of the field.

The maximum diameter of the domain is preferably 70 nm or less. In this embodiment, when the cross section of the adhesive sheet 1 is observed by TEM, it is particularly preferable that no domain is seen at a magnification of 20,000 times.

(polarizer) The polarizing plate 2 is, for example, a laminate including a polarizer and a protective film (transparent protective film). The transparent protective film is arranged, for example, so as to be in contact with the principal surface (the surface having the widest area) of the layered polarizer. The polarizer can also be arranged between two transparent protective films.

The polarizer is not particularly limited, and for example, hydrophilic polymer films such as polyvinyl alcohol-based films, partially formalized polyvinyl alcohol-based films, and ethylene-vinyl acetate copolymer-based partially saponified films absorb iodine and dichroic dyes. Such as dichroic substances and uniaxially stretched ones; polyene-based oriented films such as dehydrated polyvinyl alcohol and polyvinyl chloride dehydrochloridized products, etc. The polarizer is preferably composed of a polyvinyl alcohol-based film and a dichroic substance such as iodine.

The thickness of the polarizer is not particularly limited, for example, it may be less than 80 µm, it may be less than 50 µm, and it may be less than 30 µm. The lower limit of the thickness of the polarizer is not particularly limited, for example, it may be 1 µm, it may be 10 µm, and it may be 20 µm. The polarizer can also be a thin polarizer with a thickness of 10µm or less, preferably 1-7µm. The thin polarizer has less variation in thickness and thus has excellent visibility. The dimensional change of the thin polarizer is suppressed, so that it is excellent in durability. According to the thin polarizer, the thickness of the polarizing plate 2 can be reduced.

As the material of the transparent protective film, for example, a thermoplastic resin excellent in transparency, mechanical strength, heat stability, moisture barrier property, isotropy, etc. can be used. Specific examples of the thermoplastic resin include, for example, cellulose resins such as cellulose triacetate, polyester resins, polyether resins, polyresins, polycarbonate resins, polyamide resins, polyimide resins, Polyolefin resins, (meth)acrylic resins, cyclic polyolefin resins (northylene-based resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof. The material of the transparent protective film can also be thermosetting resins such as (meth)acrylic, urethane, acrylic urethane, epoxy, polysiloxane or ultraviolet curable resins. When the polarizing plate 2 has two transparent protective films, the materials of the two transparent protective films may be the same or different from each other. For example, a transparent protective film made of thermoplastic resin may be attached to one main surface of the polarizer through an adhesive, and a film made of thermosetting resin or ultraviolet curable resin may be attached to the other main surface of the polarizer. Transparent protective film. The transparent protective film may also contain one or more optional additives. Examples of additives include ultraviolet absorbers, antioxidants, slip agents, plasticizers, release agents, anti-coloring agents, flame retardants, nucleating agents, antistatic agents, pigments, and colorants.

The moisture permeability of the transparent protective film is not particularly limited, and may be less than 200g/(m ² ·day) or less than 50g/(m ² ·day). At this time, moisture in the air can be suppressed from invading into the polarizing plate 2 , so that changes in the moisture content of the polarizing plate 2 can be suppressed. Thereby, curling and dimensional changes of the polarizing plate 2 can be suppressed during storage or the like. Also, the lower the moisture permeability of the transparent protective film, the less likely the conductive agent in the adhesive sheet 1 will overflow, and the tendency to suppress the increase in the surface resistance of the adhesive sheet 1 over time. Materials for forming a transparent protective film with low moisture permeability include, for example, polyester-based polymers, polycarbonate-based polymers, arylate-based polymers, amide-based polymers, olefin-based polymers, and cyclic olefin-based polymers , (meth)acrylic polymers and mixtures thereof.

The moisture permeability of the transparent protective film can be measured by the following method in accordance with the moisture permeability test (moisture permeability cup method) of JIS Z0208:1976. First, the transparent protective film was cut into a diameter of 60 mm to prepare a measurement sample. Next, the measurement sample was attached to the moisture-permeable cup in which about 15 g of calcium chloride was placed. The moisture permeable cup was 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 perform a moisture permeability test. By measuring the weight increase of calcium chloride before and after the test, the moisture permeability of the transparent protective film can be specified.

The thickness of the protective film can be determined appropriately, but it is generally about 10~200µm in terms of workability such as strength and operability, and film properties.

The polarizer and the transparent protective film are usually adhered through water-based adhesives or the like. Examples of the water-based adhesive include isocyanate-based adhesives, polyvinyl alcohol-based adhesives, gelatin-based adhesives, vinyl-based latex, water-based polyurethane, and water-based polyester. Adhesives other than the above adhesives include ultraviolet curable adhesives, electron beam curable adhesives, and the like. Adhesives for electron beam hardening type polarizing plates exhibit suitable adhesiveness to various transparent protective films. The adhesive may also contain metallic compound fillers.

In the polarizing plate, a retardation film or the like may be formed on the polarizer instead of the transparent protective film. On the transparent protective film, another transparent protective film, a retardation film, etc. may be further provided.

With regard to the transparent protective film, a hard coat layer may be provided on the surface opposite to the surface attached to the polarizer, or it may be treated for anti-reflection, anti-adhesion, diffusion, and anti-glare.

The single transmittance of the polarizing plate 2 is, for example, 40%-43%. The single-body transmittance of the polarizing plate 2 is the Y value after the sensitivity is corrected according to the 2-degree field of view (C light source) of JIS Z8701:1999. The single transmittance can be measured using a commercially available spectrophotometer such as DOT-3 manufactured by Murakami Color Technology Laboratory. The measurement wavelength of monomer transmittance is 380~700nm (every 10nm).

In addition, the polarizing plate 2 does not have to have a layer for suppressing transmission of iodine. The layer that inhibits iodine permeation is, for example, a layer of a boron-containing acrylic resin having a structural unit derived from a monomer represented by the following formula (2). Specifically, it includes a layer obtained by polymerizing a monomer mixture. In the layer of the copolymer, the monomer mixture comprises more than 50 parts by weight of a (meth)acrylic monomer and more than 0 parts by weight and less than 50 parts by weight of a monomer represented by the following formula (2). X in formula (2) represents a functional group comprising a reactive group, and the reactive group is selected from vinyl, (meth)acryl, styryl, (meth)acrylamide, ethylene At least one reactive group selected from the group consisting of ether group, epoxy group, oxetanyl group, hydroxyl group, amine group, aldehyde group and carboxyl group. R ¹ and R ² of formula (2) independently represent a hydrogen atom, an aliphatic hydrocarbon group that may have a substituent, an aryl group that may have a substituent or a heterocyclic group that may have a substituent, and R ¹ and R ² may be connected to each other Form a ring. [chemical formula 2]

For example, the optical laminate 10A of this embodiment excludes the following polarizing plate, which has: a polarizer, a protective layer disposed on one side of the polarizer, and a protective layer disposed on the other side of the polarizer. A layer for inhibiting iodine transmission, and an adhesive layer disposed on the opposite side of the layer for inhibiting iodine transmission from the polarizer; the layer for inhibiting iodine transmission is a cured product or thermally cured coating film of an organic solvent solution of a resin The adhesive composition constituting the adhesive layer includes a base polymer and an antistatic agent; the glass transition temperature of the base polymer is below -50°C, and the dielectric constant at 100kHz is above 5.0; the adhesive The surface resistance value of the layer is 1.0×10 ⁹ Ω/□ or less.

The shape of the polarizer 2 is, for example, rectangular in plan view, and may not be irregular. Specifically, the polarizing plate 2 does not need to have the irregularly processed portion. Irregularly processed parts include through holes, chamfered corners, and cut parts that become concave parts when viewed from above. Specific examples of the recess include a boat-like shape, a bathtub-like shape, a V-shaped notch, and a U-shaped notch. Another example of the special-shaped processing part is a shape corresponding to the dashboard of an automobile. The shape is that the outer edge forms a circular arc along the direction of rotation of the instrument needle, and includes a part where the outer edge forms a V-shape (including an arc) protruding inward in the surface direction.

For example, the optical laminate 10A of this embodiment excludes the following polarizing plate, the polarizing plate is equipped with an adhesive layer; and the polarizing plate has an irregular shape; substance and antistatic agent; the glass transition temperature of the base polymer is below -50°C, and the dielectric constant at 100kHz is above 5.0; the surface resistance of the adhesive layer is below 1.0×10 ⁹ Ω/□.

Another example of the optical layered body of this embodiment is shown in FIG. 4 . The optical laminate 10B in FIG. 4 has the following laminated structure: a release liner 3 , an adhesive sheet 1 and a polarizing plate 2 are laminated in this order. The optical layered body 10B can be used as a polarizing plate with an adhesive sheet by peeling off the release liner 3 . The following examples can also be combined with each other as long as there is no technical contradiction.

The constituent materials of the release liner 3 include, for example: plastic films such as polyethylene, polypropylene, polyethylene terephthalate, and polyester film; porous materials such as paper, cloth, and non-woven fabric; Suitable thin sheets such as blister sheets, metal foils, and their laminates can be suitably used for plastic films because of their excellent surface smoothness.

The plastic film is not particularly limited if it is a film that can protect the adhesive sheet 1, for example: polyethylene film, polypropylene film, polybutene film, polybutadiene film, polymethylpentene film, polyvinyl chloride film Film, vinyl chloride copolymer film, polyethylene terephthalate film, polybutylene terephthalate film, polyurethane film, ethylene-ethyl acetate copolymer film, etc.

The thickness of the release liner 3 is usually 5-200 µm, preferably about 5-100 µm. For the release liner 3, release and anti-fouling treatment, coating type, kneading type, etc. , Evaporation type and other antistatic treatment. 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 adhesive sheet 1 can be further improved.

In addition, as mentioned above, the release film used when producing the adhesive sheet 1 can also be used as the release liner 3 .

Another example of the optical layered body of this embodiment is shown in FIG. 5 . The optical laminate 10C in FIG. 5 has the following laminate structure: a release liner 3 , an adhesive sheet 1 , a retardation film 5 , an interlayer adhesive 4 and a polarizing plate 2 are laminated in sequence. The optical layered body 10C can be used after peeling off the release liner 3, for example, by affixing it to an image display unit.

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

Retardation film 5 can enumerate retardation film for anti-reflection (refer to Japanese Patent Laid-Open No. 2012-133303 communique [0221], [0222], [0228]), viewing angle compensation retardation film (refer to Japanese Patent Laid-Open No. 2012- [0225], [0226] of Publication No. 133303), oblique orientation retardation film for viewing angle compensation (refer to [0227] of Japanese Patent Application Laid-Open No. 2012-133303), etc.

As long as the retardation film 5 substantially has the above-mentioned functions, there are no particular limitations such as retardation value, arrangement angle, three-dimensional birefringence, single layer or multilayer, and known retardation films can be used.

The thickness of the retardation film 5 is preferably less than 20 µm, more preferably less than 10 µm, more preferably 1-9 µm, especially 3-8 µm.

The retardation film 5 is composed of, for example, two layers of a 1/4 wavelength plate and a 1/2 wavelength plate in which a liquid crystal material is oriented and immobilized.

A well-known adhesive can be used for the interlayer adhesive 4. The adhesive sheet 1 can also be used for the interlayer adhesive 4 .

Another example of the optical layered body of this embodiment is shown in FIG. 6 . The optical laminate 10D in FIG. 6 has the following laminated structure: a release liner 3 , an adhesive sheet 1 , a retardation film 5 , an interlayer adhesive 4 , a polarizing plate 2 and a protective film 6 are laminated in sequence. The optical layered body 10D can be used after peeling off the release liner 3, for example, by being attached to an image display unit.

The protective film 6 has the function of protecting the outermost polarizing plate 2 when the optical layered body 10D is distributed and stored, and when the optical layered body 10D is incorporated into an image display device. In addition, in a state where an image display device is incorporated, the protective film 6 functioning as a window to the external space may also be used. 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, preferably polyester. However, the protective film 6 is not limited to the above examples. The protective film 6 may be a glass film or a laminated film including a glass film. Surface treatments such as anti-glare, anti-reflection, and anti-static can also be applied to the protective film 6 .

The protective film 6 can also be bonded to the polarizer 2 by any adhesive. It can also be joined by the adhesive sheet 1 .

The optical layered body of this embodiment can be distributed and stored, for example, in the form of a winding body in which a belt-shaped optical layered body is wound, or in the form of a single-sheet optical layered body. The optical layered body of this embodiment is suitable for use in image display devices in an environment where static electricity is particularly likely to be generated, and is particularly suitable for use in in-vehicle displays. Examples of in-vehicle displays include panels for car navigation devices, instrument panels, mirror displays, and the like. A dashboard is a panel that displays the speed of the vehicle or the number of revolutions of the engine, etc.

[Example of video display panel] An example of the video display panel of this embodiment is shown in FIG. 7 . The image display panel 11A of FIG. 7 includes an optical laminate 10A, and further includes, for example, an image display unit 30A. Specifically, the optical laminate 10A is attached to the image display unit 30A through the adhesive sheet 1 . In addition, the optical layered body 10B, 10C, or 10D of FIGS. 4 to 6 may be used instead of the optical layered body 10A (except for the release liner 3 ).

The image display unit 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, for example, arranged between the first transparent substrate 31 and the second transparent substrate 33 , and is in contact with the first transparent substrate 31 and the second transparent substrate 33 respectively. The adhesive sheet 1 of the optical laminate 10A is in contact with the first transparent substrate 31 of the image display unit 30A, for example.

The image forming layer 32 is, for example, a liquid crystal layer including liquid crystal molecules that are homeotropically 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, in-plane switching) method. However, the liquid crystal layer can also be used in TN (Twisted Nematic) type, STN (Super Twisted Nematic) type, π type, VA (Vertical Alignment) type, etc. In this specification, an image display unit including a liquid crystal layer may be referred to as a liquid crystal unit, and an image display panel including a liquid crystal unit may be referred to as a liquid crystal panel. In addition, the image forming layer 32 can also be an EL light emitting layer.

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

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

The image display unit 30A may further include other layers other than the image forming layer 32 , the first transparent substrate 31 and the second transparent substrate 33 . Other layers include, for example, color filters, easy-adhesive layers, and hard coat layers. The color filter is arranged, for example, on the viewing side of the image forming layer 32 , preferably between the first transparent substrate 31 and the adhesive sheet 1 of the optical laminate 10A. The easy-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 unit 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. If the conductive structure is connected to the ground, it becomes easy to suppress electrostatic charging of the optical layered body 10A. The conduction structure may cover the entire side of the optical laminate 10A, or partially cover the side of the optical laminate 10A. The ratio of the area of the side surface of the optical layered body 10A to the area of the entire side surface of the optical layered body 10A is, for example, 1% or more, preferably 3% or more.

The material of the conduction structure can be, for example: conductive paste made of metals such as silver and gold; conductive adhesive; other conductive materials. The conductive structure may be a wiring extending from the side surface of the optical layered body 10A.

The image display panel 11A may further include other optical films other than the polarizer 2 . Other optical films can be, for example, polarizers, reflectors, anti-transmission films, viewing angle compensation films, brightness enhancement films and other films that can be used in image display devices. The image display panel 11A may also include one or more than two other optical films among these.

When the other optical film is a polarizing plate, the polarizing plate is bonded to the second transparent substrate 33 of the image display unit 30A, for example, through an adhesive sheet. The polarizer has, for example, the configuration described above for the polarizer 2 . In polarizing plates used as other optical films, the transmission axis (or absorption axis) of the polarizer is, for example, perpendicular to the transmission axis (or absorption axis) of the polarizer in the polarizing plate 2 . The material of the adhesive sheet for laminating the polarizing plate and the second transparent substrate 33 can be used as described above for the adhesive sheet 1 . The thickness of the adhesive sheet is not particularly limited, for example, it is 1-100 µm, preferably 2-50 µm, more preferably 2-40 µm, more preferably 5-35 µm.

Another example of the image display panel of this embodiment is shown in FIG. 8 . The image display panel 11B of FIG. 8 is further provided with a conductive layer 40 , and the conductive layer 40 is disposed between the optical laminate 10A and the image display unit 30A. However, the image display panel is preferably the image display panel 11A without the conductive layer 40 . The image display panel 11B provided with the conductive layer 40 tends to have high reflectance, and the visibility of the display may be reduced. In the image display panel 11A that does not contain the conductive layer 40, it is preferable to provide a conduction portion adjacent to the adhesive sheet 1 (the above-mentioned conduction structure). For the vias, for example, conductive silver paste can be used. After bonding the optical laminate 10A to the image display unit 30A, apply conductive silver paste or the like to the side of the adhesive sheet 1 to form a conduction portion, and conduct from there to other wiring or the frame of the image display device, etc. Thereby, the antistatic property of the image display panel can be improved.

The conductive layer 40 is, for example, a layer containing a conductive agent. As the conductive agent, metal oxides, conductive polymers, those described above for the adhesive sheet 1, and the like can be used. The thickness of the conductive layer 40 is, for example, 5 nm˜180 nm. The surface resistance of the conductive layer 40 is, for example, 1.0×10 ⁶ Ω/□~1.0×10 ¹⁰ Ω/□, preferably 1.0×10 ⁸ Ω/□~1.0×10 ⁹ Ω/□.

The image display panel in this embodiment can also be an image display panel with a built-in touch sensing function. An example of an image display panel with a built-in touch sensing function is shown in FIG. 9 . The image display panel 11C of FIG. 9 is provided with an image display unit 30B further including a touch sensing electrode portion 35 . In the image display unit 30B, the touch sensing electrode portion 35 is disposed between the first transparent substrate 31 and the second transparent substrate 33 . The touch sensing electrode part 35 has functions of a touch sensor and a touch driver. Video display panel 11C is a so-called built-in video display panel, and video display unit 30B is a so-called built-in video display unit. However, in the image display unit 30B, the touch-sensing electrode portion 35 may also be disposed on the viewing side of the first transparent substrate 31 . That is, the image display panel 11C may be a so-called top-mounted image display panel, and the image display unit 30B may also be a so-called top-mounted image display unit.

The touch sensing electrode part 35 has, for example, a touch sensor electrode 36 and a touch driving electrode 37 . The touch sensor electrode 36 means a (receiving) electrode for touch detection. Each of the touch sensor electrodes 36 and the touch driving electrodes 37 can be independently formed by various patterns. For example, when the image display unit 30B is flat, the touch sensor electrodes 36 and the touch driving electrodes 37 can be independently arranged in the X-axis direction and the Y-axis direction respectively, forming these patterns that intersect at right angles. In FIG. 9 , in the touch sensing electrode portion 35 , the touch sensor electrode 36 is disposed on the viewing side of the touch driving electrode 37 . However, the touch driving electrodes 37 may also be disposed on the viewing side of the touch sensor electrodes 36 . In the touch sensing electrode portion 35 , the touch sensor electrodes 36 and the touch driving electrodes 37 may also be integrated.

In FIG. 9 , the touch-sensing electrode portion 35 is disposed between the image forming layer 32 and the first transparent substrate 31 (more visible side than the image forming layer 32 ). However, the touch-sensing electrode portion 35 may also be disposed between the image forming layer 32 and the second transparent substrate 33 (closer to the lighting system side than the image forming layer 32 ).

In the touch sensing electrode portion 35 , the touch sensor electrodes 36 and the touch driving electrodes 37 may not be in contact with each other. For example, the touch sensor electrodes 36 can also be disposed between the image forming layer 32 and the first transparent substrate 31 , and the touch driving electrodes 37 can also be disposed between the image forming layer 32 and the second transparent substrate 33 .

The driving electrodes (the touch driving electrodes 37 , or the integrated electrodes of the touch sensor electrodes 36 and the touch driving electrodes 37 ) in the touch sensing electrode portion 35 can also serve as common electrodes for controlling the image forming layer 32 .

The touch sensor electrodes 36 (capacitive sensors), the touch drive electrodes 37 , or the integrated electrodes forming the touch sensing electrode portion 35 function as a transparent conductive layer. The material of the transparent conductive layer is not particularly limited, and examples include metals such as gold, silver, copper, platinum, palladium, aluminum, nickel, chromium, titanium, iron, cobalt, tin, magnesium, tungsten, and alloys thereof. The material of the transparent conductive layer can also be oxides of metals such as indium, tin, zinc, gallium, antimony, zirconium, and cadmium. The oxide specifically includes indium oxide, tin oxide, titanium oxide, cadmium oxide, and mixtures thereof. The material of the transparent conductive layer can also be a metal compound such as copper iodide. The material of the transparent conductive layer is preferably indium oxide containing tin oxide (ITO), tin oxide containing antimony, etc., and ITO is particularly preferred. When the material of the transparent conductive layer is ITO, the content of indium oxide in the transparent conductive layer is preferably 80-99% by weight, and the content of tin oxide is preferably 1-20% by weight.

The electrodes (the touch sensor electrodes 36 , the touch drive electrodes 37 , or the integrated electrodes) constituting the touch sensing electrode portion 35 can be used between the first transparent substrate 31 and the second transparent substrate 33 A conventional method is to form a transparent electrode pattern. The transparent electrode pattern is, for example, electrically connected to the winding wire formed at the end of the transparent substrate. The wires are connected to, for example, a controller IC. The shape of the transparent electrode pattern can be any shape such as comb shape, stripe shape, rhombus shape, etc. according to the application. The thickness of the transparent electrode pattern is, for example, 10 nm˜100 nm. The width of the transparent electrode pattern is, for example, 0.1 mm˜5 mm.

[Embodiment of Image Display Device] The image display device of this embodiment includes, for example, an image display panel 11A and an illumination system. In addition, the image display panels 11B and 11C in FIGS. 8 to 9 may also be used instead of the image display panel 11A. In the image display device, for example, the image display panel 11A is disposed on the viewing side of the lighting system. The lighting system includes, for example, a backlight or a reflector, and irradiates light to the image display panel 11A.

The image display device may be an organic EL display or a liquid crystal display. However, the image display device is not limited to this example. The image display device may also be an electroluminescence (EL) display, a plasma display (PD), a field emission display (FED: Field Emission Display) and the like. The image display device can be used in home appliances, in-vehicles, public information displays (PIDs), etc., and is preferably an in-vehicle display.

Example The present invention will be described in detail below by means of examples. The present invention is not limited by the Examples shown below.

(Production of Polarizing Plate) First, the polyvinyl alcohol film with a thickness of 80 μm is dyed in an iodine solution with a temperature of 30°C and a concentration of 0.3% between rollers with different speed ratios for 1 minute and stretched until it reaches 3 times. Next, it was stretched until the total stretching ratio reached 6 times while dipping it in an aqueous solution at a temperature of 60° C. containing 4% boric acid and 10% potassium iodide for 0.5 minutes. Next, it was dipped in an aqueous solution containing potassium iodide at a concentration of 1.5% at a temperature of 30° C. for 10 seconds, and then dried at 50° C. for 4 minutes to obtain a polarizer with a thickness of 28 μm. A transparent protective film with a thickness of 30 µm made of a modified acrylic polymer with a lactone ring structure was bonded to one side of the polarizer with a polyvinyl alcohol-based adhesive. A cellulose triacetate film (manufactured by Konica Minolta, trade name "KC4UY") with a hard coat layer (HC) formed on a transparent protective film with a thickness of 47 µm was bonded to the other side of the polarizer with a polyvinyl alcohol-based adhesive. one side. This was heated and dried for 5 minutes in an oven set at 70° C., thereby producing a polarizing plate.

<The weight-average molecular weight of the (meth)acrylic polymer> In the following examples, the weight-average molecular weight (Mw) of the (meth)acrylic polymer was measured by GPC (gel permeation chromatography). The Mw/Mn of the (meth)acrylic polymer was also measured in the same manner.・Analyzer: Tosoh Corporation, HLC-8120GPC ・Column: Tosoh Corporation, G7000H _XL + GMH _XL + GMH _XL・Column size: 7.8mmφ×30cm each, 90cm in total ・Column temperature: 40°C・Flow rate: 0.8mL/min ・Injection volume: 100µL ・Eluent: THF ・Detector: Differential refractometer (RI) ・Standard sample: Polystyrene

(Example 1) ＜Preparation of (meth)acrylic polymer A1＞ First, a monomer mixture containing 99 parts by weight of methoxyethyl acrylate and 1 part by weight of 4-hydroxybutyl acrylate was fed into a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen gas introduction tube, and a cooler. And 0.1 weight part of 2,2'- azobisisobutyronitrile (AIBN) as a polymerization initiator was fed with 100 weight part of ethyl acetate with respect to 100 weight part of monomer mixtures. While slowly stirring the mixture, nitrogen gas was introduced into the flask to perform nitrogen substitution. A solution of (meth)acrylic polymer A1 with a weight average molecular weight (Mw) of 1,800,000 and Mw/Mn=4.4 was prepared by maintaining the liquid temperature in the flask at around 55° C. for 8 hours of polymerization reaction.

[Preparation of (meth)acrylic adhesive composition] Next, 0.4 parts by weight of an isocyanate-based crosslinking agent (Coronate L manufactured by Tosoh, trimethylolpropane toluene diisocyanate) was further blended with respect to 100 parts by weight of the solid content of the solution of the (meth)acrylic polymer A1. , 0.1 parts by weight of peroxide-based crosslinking agent (NYPER BMT manufactured by NOF Corporation), 0.2 parts by weight of silane coupling agent (KBM-403 manufactured by Shin-Etsu Chemical Industry Co., Ltd., γ-glycidoxypropyl methyl oxysilane) and 5 parts by weight of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd) as a conductive agent to prepare a (meth)acrylic Solution of adhesive composition.

[Production of optical laminates] Next, apply the solution of the (meth)acrylic adhesive composition on the polyethylene terephthalate film treated with the silicone release agent so that the thickness of the adhesive sheet after drying becomes 20 µm (Release liner: MRF38, manufactured by Mitsubishi Polyester Film Co., Ltd.) on one side. The obtained coating film was dried at 155° C. for 1 minute, thereby forming an adhesive sheet on the surface of the release liner. Next, the adhesive sheet formed on the release liner was transferred to the above-mentioned polarizing plate, and the optical laminate of Example 1 (polarizing plate with an adhesive sheet) was produced. In addition, the adhesive sheet was transferred to the surface of the polarizing plate on the side of the transparent protective film made of modified acrylic polymer.

(Example 2) In preparing the (meth)acrylic adhesive composition, the blending amount of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.)) was changed to 10 In addition to this, the optical laminate of Example 2 was produced in the same manner as in Example 1.

(Example 3) In preparing the (meth)acrylic adhesive composition, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (Elexcel AS-110, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.)5 was used The optical laminate of Example 3 was produced in the same manner as in Example 1 except that the weight part was used as a conductive agent.

(Example 4) In preparing the (meth)acrylic adhesive composition, 1-ethyl-3-methylimidazolium bis(fluorosulfonyl)imide (Elexcel AS-110, manufactured by Daiichi Kogyo Pharmaceutical Co., Ltd.) was used10 The optical laminate of Example 4 was produced in the same manner as in Example 1 except that the weight part was used as a conductive agent.

(Example 5) Use a monomer mixture containing 69 parts by weight of butyl acrylate, 30 parts by weight of methoxyethyl acrylate and 1 part by weight of 4-hydroxybutyl acrylate to prepare (meth)acrylic polymer A2 to replace (meth)acrylic acid The optical laminate of Example 5 was produced in the same manner as in Example 1 except that it was polymer A1. The (meth)acrylic polymer A2 had a weight average molecular weight (Mw) of 1,800,000, and Mw/Mn=4.1.

(Example 6) Use a monomer mixture containing 79 parts by weight of butyl acrylate, 20 parts by weight of methoxytriethylene glycol acrylate and 1 part by weight of 4-hydroxybutyl acrylate to prepare (meth)acrylic polymer A3 to replace ( The optical laminate of Example 6 was produced in the same manner as in Example 1 except for the meth)acrylic polymer A1. The (meth)acrylic polymer A3 had a weight average molecular weight (Mw) of 1,800,000, and Mw/Mn=4.0.

(Example 7) (meth)acrylic polymer A4 was prepared using a monomer mixture containing 79 parts by weight of methoxyethyl acrylate, 20 parts by weight of methoxytriethylene glycol acrylate and 1 part by weight of 4-hydroxybutyl acrylate. The optical laminate of Example 7 was produced in the same manner as in Example 1 except that the (meth)acrylic polymer A1 was replaced. The (meth)acrylic polymer A4 had a weight average molecular weight (Mw) of 1,800,000, and Mw/Mn=4.3.

(comparative example 1) [Preparation of (meth)acrylic polymer A5] First, in a four-necked flask equipped with a stirring blade, a thermometer, a nitrogen inlet pipe and a cooler, feed 77 parts by weight of butyl acrylate, 18 parts by weight of benzyl acrylate, 4.8 parts by weight of acrylic acid and 0.2 parts by weight of 4-hydroxybutyl acrylate. A monomer mixture in parts by weight. And 0.1 weight part of 2,2'- azobisisobutyronitrile (AIBN) as a polymerization initiator was fed with 100 weight part of ethyl acetate with respect to 100 weight part of monomer mixtures. While slowly stirring the mixture, nitrogen gas was introduced into the flask to perform nitrogen substitution. A solution of (meth)acrylic polymer A5 with a weight average molecular weight (Mw) of 2,000,000 and Mw/Mn=4.0 was prepared by maintaining the liquid temperature in the flask at around 55° C. for 8 hours of polymerization reaction.

[Preparation of (meth)acrylic adhesive composition] Next, 0.45 parts by weight of an isocyanate-based crosslinking agent (Coronate L manufactured by Tosoh, trimethylolpropane toluene diisocyanate) was further blended with respect to 100 parts by weight of the solid content of the solution of (meth)acrylic polymer A5. , 0.1 parts by weight of peroxide-based crosslinking agent (NYPER BMT manufactured by NOF Corporation), 0.2 parts by weight of silane coupling agent (KBM-403 manufactured by Shin-Etsu Chemical Industry Co., Ltd., γ-glycidoxypropyl methyl oxysilane) and 10 parts by weight of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI, manufactured by Mitsubishi Materials Electronic Chemicals Co., Ltd.) as a conductive agent to prepare a (meth)acrylic acid Solution of adhesive composition.

[Production of optical laminates] Next, apply the solution of the (meth)acrylic adhesive composition on the polyethylene terephthalate film treated with the silicone release agent so that the thickness of the adhesive sheet after drying becomes 20 µm (Release liner: MRF38, manufactured by Mitsubishi Polyester Film Co., Ltd.) on one side. The obtained coating film was dried at 155° C. for 1 minute, thereby forming an adhesive sheet on the surface of the release liner. Next, the adhesive sheet formed on the release liner was transferred to the above-mentioned polarizing plate, and an optical laminate of Comparative Example 1 was produced. In addition, the adhesive sheet was transferred to the surface of the polarizing plate on the side of the transparent protective film made of modified acrylic polymer.

(comparative example 2) The optical laminate of Comparative Example 2 was produced in the same manner as in Comparative Example 1 except that no conductive agent was mixed in the preparation of the (meth)acrylic adhesive composition.

＜Measurement of Relative Permittivity＞ The measurement of the relative permittivity of the produced (meth)acrylic polymer at a frequency of 100 kHz was carried out by the above-mentioned method.

＜Measurement of Surface Resistance＞ The release liner was peeled off from the prepared optical laminate, and the surface resistance value of the adhesive sheet was measured. The measurement of the surface resistance value was carried out using MCP-HT450 manufactured by Mitsubishi Chemical Analytech under conditions of an applied voltage of 250 V and an applied time of 10 seconds. The measurement of the surface resistance value of the adhesive sheet was carried out on the optical layered body immediately after production and the optical layered body after humidification treatment. The humidification treatment was carried out by the above-mentioned test method 3.

＜ESD test＞ Electrostatic discharge (ESD) tests were performed on the produced optical laminates by the following method. First, the release liner is peeled off from the optical laminate, and attached to the viewing side surface of the built-in liquid crystal unit to produce a liquid crystal panel with built-in touch sensing function. Next, static electricity was applied to the viewing side (polarizer side) of the liquid crystal panel using an electrostatic discharge (ESD) gun whose applied voltage was adjusted to 10 kV. After static electricity was applied, the time until the whitish part disappeared was measured, and the following criteria were used for evaluation. In addition, the ESD test is carried out on the optical layered body just after production and the optical layered body after humidification treatment. The humidification treatment was carried out by the method described above for the measurement of the surface resistance value. (Assessment basis) A: Whitening was not recognized. B: Whitening disappeared within 1 second. C: The whitening disappeared within more than 1 second and within 10 seconds. D: Whitening disappeared after more than 10 seconds.

<Measurement of haze> An evaluation sample with an optical laminate was produced by the above method, and the initial haze _H0 of the evaluation sample was measured and the evaluation sample was placed in a heating environment at 105°C for 250 hours. Haze H. Specifically, samples for evaluation were produced by the following method. First, the optical layered body was cut into a size of 50 mm in length and 50 mm in width, and the release liner was peeled off. Bond the optical laminate and the alkali-free glass through the adhesive sheet. Next, a 250-µm-thick transparent adhesive sheet (LUCIACS CS98210U manufactured by Nitto Denko Co., Ltd.) made of an acrylic transparent adhesive was placed on the HC layer of the polarizing plate. The optical laminate was bonded to another non-alkali glass through a transparent adhesive sheet to prepare a sample for evaluation. In addition, the haze was measured using a haze meter (HM-150N manufactured by Murakami Color Technology Laboratory).

＜Tint evaluation＞ An evaluation sample having an optical layered body was produced by the following method, and the color tone was evaluated. First, the optical laminate was cut into a size of 200 mm long x 50 mm wide, and the release liner was peeled off. Bond the optical laminate and the alkali-free glass through the adhesive sheet. Next, a 250-µm-thick transparent adhesive sheet (LUCIACS CS98210U manufactured by Nitto Denko Co., Ltd.) made of an acrylic transparent adhesive was placed on the HC layer of the polarizing plate. The optical laminate was bonded to another non-alkali glass through a transparent adhesive sheet to prepare a sample for evaluation. Next, a light source (CIE standard light source D65) in which an additional polarizing plate was arranged was prepared, and it was arranged to face the surface of the evaluation sample on the side closer to the adhesive sheet than the polarizing plate. In this case, the additional polarizing plate was arranged between the light source and the evaluation sample so as to form a cross-polarized relationship with respect to the absorption axis of the polarizing plate in the optical layered body. Next, the light from the light source was made incident on the surface of the sample for evaluation through the additional polarizing plate in the dark room. The color tone of the transmitted light of the transmission evaluation sample was confirmed with the naked eye, and the evaluation was performed based on the results of the evaluation sample having the optical laminate of Comparative Example 2 that did not contain a conductive agent, according to the following indicators. In addition, the evaluation of color tone was also performed about the evaluation sample arrange|positioned in the heating environment of 105 degreeC after 250 hours. Regarding the evaluation sample including the optical layered body of Comparative Example 2, unnecessary coloring was not seen in the above-mentioned transmitted light before and after being placed in a heating environment. (Assessment basis) A: The transmitted light exhibited the same level of color tone as the transmitted light transmitted through the evaluation sample including the optical layered body of Comparative Example 2. C: The transmitted light exhibited a deeper color tone (green) than the transmitted light transmitted through the evaluation sample having the optical layered body of Comparative Example 2.

[Table 1]

The abbreviations in Table 1 are as follows. BA: n-butyl acrylate MEA: methoxyethyl acrylate MTGA: Methoxytriethylene glycol acrylate BzA: benzyl acrylate AA: Acrylic HBA: 4-Hydroxybutyl Acrylate AIBN: Azo-based polymerization initiator, 2,2'-azobisisobutyronitrile (manufactured by KISHIDA Chemical Co., Ltd.)

[Table 2]

The abbreviations in Table 2 are as follows. LiTFSI: lithium bis(trifluoromethanesulfonyl)imide AS-110: 1-Eth-3-methylimidazolium bis(fluorosulfonyl)imide

It can be seen from Table 2 that the optical laminates of the examples include an adhesive sheet with a sufficiently low surface resistance, and even after being exposed to a high temperature environment, the results of color tone evaluation are still good. From the results in Table 2, it can be inferred that the optical laminates of the examples are suitable for suppressing unwanted coloring of light from an image display device even after being subjected to a high-temperature environment.

On the other hand, when the optical layered body of Comparative Example 1 passed through a high-temperature environment, the transmitted light was colored green in color tone evaluation. In the optical laminate of Comparative Example 2, the surface resistance value of the adhesive sheet was insufficient, and the result of the ESD test was inferior to that of Examples.

Industrial availability The optical layered body of the present invention can be suitably utilized for image display devices such as EL displays and liquid crystal displays.

1: Adhesive sheet 2: polarizer 3: Peel off the lining 4: interlayer adhesive 4 5: Retardation film 6: Protective film 10A, 10B, 10C, 10D: optical laminates 11A, 11B, 11C: video display panel 15: Samples for evaluation 20, 20A, 20B: Alkali-free glass 21: Transparent adhesive sheet 22: Additional polarizer 23: light source 30A, 30B: image display unit 31: The first transparent substrate 32: Image cambium 33: Second transparent substrate 35: Touch sensing electrode part 36: Touch sensor electrode 37: Touch driving electrode 40: Conductive layer

Fig. 1 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. Fig. 2 is a cross-sectional view schematically showing an evaluation sample including an optical layered body. Fig. 3 is a diagram for explaining an evaluation method using an evaluation sample. Fig. 4 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. Fig. 5 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. Fig. 6 is a cross-sectional view schematically showing an example of the optical layered body of the present invention. FIG. 7 is a cross-sectional view schematically showing an example of an image display panel of the present invention. FIG. 8 is a cross-sectional view schematically showing an example of the image display panel of the present invention. FIG. 9 is a cross-sectional view schematically showing an example of an image display panel of the present invention.

1: Adhesive sheet

2: polarizer

10A: Optical laminate

Claims (18)

An optical laminate comprising an adhesive sheet and a polarizing plate, and the adhesive sheet is formed of an adhesive composition containing a polymer (A); the relative dielectric constant of the aforementioned polymer (A) at a frequency of 100 kHz is 5.0 or more; The surface resistance value of the above-mentioned adhesive sheet is 1.0×10 ¹⁰ Ω/□ or less; the haze of the optical laminate measured by the following test method is 1.0% or less; Test method: The above-mentioned optical laminate is sandwiched by two pieces of non-alkali glass body to prepare a sample for evaluation; after heating the sample for evaluation at 105° C. for 250 hours, measure the haze of the sample for evaluation. The optical laminate according to claim 1, wherein the surface resistance value is 2.0×10 ⁸ Ω/□ or less. The optical laminate according to claim 1 or 2, wherein the relative permittivity is 7.5 or more. The optical laminate according to any one of claims 1 to 3, wherein the adhesive composition contains a conductive agent. The optical laminate according to claim 4, wherein in the adhesive composition, the blending amount of the conductive agent is 3.0 parts by weight or more with respect to 100 parts by weight of the polymer (A). The optical laminate according to claim 4 or 5, wherein in the adhesive composition, the blending amount of the conductive agent is 10 parts by weight or less with respect to 100 parts by weight of the polymer (A). The optical laminate according to any one of claims 4 to 6, wherein the conductive agent is an ionic compound. The optical laminate according to any one of claims 1 to 7, wherein the adhesive composition contains a peroxide-based crosslinking agent. The optical laminate according to any one of claims 1 to 8, wherein the aforementioned polymer (A) has a structural unit derived from an alkoxy group-containing monomer. The optical laminate according to Claim 9, wherein the aforementioned alkoxy-containing monomer system is represented by the following formula (1): [Chemical Formula 1] In the aforementioned formula (1), R ¹ is a hydrogen atom or a methyl group, R ² is an alkyl group, and n is an integer of 1 to 30. The optical laminate according to claim 9 or 10, wherein the content of the structural unit derived from the alkoxy-containing monomer in the polymer (A) is 15% by weight or more. The optical laminate according to any one of claims 1 to 11, wherein the content of the structural unit derived from a carboxyl group-containing monomer in the polymer (A) is less than 0.1% by weight. The optical laminate according to any one of claims 1 to 12, wherein the glass transition temperature of the polymer (A) is -50°C or lower. The optical laminate according to any one of claims 1 to 13, wherein the ratio (Mw/Mn) of the weight average molecular weight Mw of the polymer (A) to the number average molecular weight Mn is 20 or less. The optical laminate according to any one of claims 1 to 14, wherein the single transmittance of the polarizing plate is 40% to 43%. The optical laminate according to any one of Claims 1 to 15, wherein the a ^* value and b ^* value in the L ^* a ^* b ^* colorimetric system of the transmitted light measured by the following test method satisfy the following relationship (I) and (II): Test method: The above-mentioned optical laminate is sandwiched by two pieces of non-alkali glass to make an evaluation sample; the above-mentioned evaluation sample is heated at 105°C for 250 hours; an additional polarized light is prepared and placed The light source of the plate (CIE standard light source D65), the additional polarizing plate forms a relationship of orthogonal polarization to the absorption axis of the aforementioned polarizing plate in the aforementioned optical laminate; the light from the aforementioned light source passes through the aforementioned additional polarizing plate incident phase The surface of the aforementioned evaluation sample on the side closer to the aforementioned adhesive sheet than the aforementioned polarizing plate; measure the a ^* value and b ^* value in the L ^* a ^* b ^* colorimetric system of the transmitted light transmitted through the aforementioned evaluation sample; - 0.3≦a ^* ≦0.7 (I) -1.5≦b ^* ≦0.5 (II). An image display panel comprising the optical laminate according to any one of Claims 1 to 16. An image display device, comprising the image display panel according to claim 17.