JP7382264B2 - Polarizing film and image display device - Google Patents

Description

The present invention relates to a polarizing film and an image display device.

Image display devices such as liquid crystal display devices and organic EL display devices include polarizing films for reasons such as their display principles. A polarizing film is, for example, a laminate including a polarizer and a transparent protective film. A polarizer can generally be produced by adsorbing a dichroic dye onto a hydrophilic polymer film such as a polyvinyl alcohol (PVA) film and uniaxially stretching the film. Iodine is widely used as the dichroic dye from the viewpoint of improving the transmittance and degree of polarization of the polarizer.

Patent Document 1 discloses an optical laminate in which a polarizer and a protective film are bonded together via a cured layer of a curable resin composition. Patent Document 1 discloses that by appropriately adjusting the content of the alicyclic epoxy compound in the curable resin composition, even when the optical laminate is placed in a hot and humid environment, iodine in the cured layer can be reduced. It can be seen that the content of can be maintained low.

Japanese Patent Application Publication No. 2018-169512

In a hot and humid environment, iodine contained in a polarizer tends to migrate from the polarizer to a transparent protective film or an adhesive layer for bonding the polarizing film to an image display panel. In particular, when the thickness of the polarizer is small and the concentration of iodine in the polarizer is high, iodine tends to move from the polarizer to the transparent protective film or adhesive layer. The iodine that has moved to the transparent protective film or adhesive layer is transmitted to the outside of the polarizing film through the transparent protective film or adhesive layer. When the content of iodine in the polarizer decreases, the degree of polarization of the polarizing film decreases.

Conventional polarizing films cannot sufficiently suppress transmission of iodine contained in the polarizer to the outside of the polarizing film in a high temperature and high humidity environment. For example, Patent Document 1 focuses on maintaining the iodine content in the cured layer at a low level when the optical laminate is placed in a high temperature and high humidity environment. However, Patent Document 1 does not consider that iodine is transmitted from the polarizer to the outside of the optical laminate.

Therefore, an object of the present invention is to provide a polarizing film that can sufficiently suppress transmission of iodine contained in a polarizer to the outside in a high temperature and high humidity environment.

As a result of extensive studies, the present inventors have determined that, in a polarizing film including a resin layer, the tensile storage modulus of the resin layer, the linear expansion coefficient of the resin layer, and the monomer content for forming the polymer contained in the resin layer. The present invention was completed based on the new discovery that each dipole moment can be used as an index regarding the permeation of iodine to the outside.

The present invention
A polarizer containing iodine,
A resin layer containing a polymer,
A polarizing film that satisfies at least one of the following requirements (i) to (v) is provided.
(i) The tensile storage modulus E1 of the resin layer at 65° C. in water is 1×10 ⁸ Pa or more.
(ii) The resin layer has a tensile storage modulus E2 of 1×10 ⁸ Pa or more at 85° C. in water.
(iii) The resin layer has a linear expansion coefficient α1 of 400×10 ^-6 /K or less when the resin layer is heated from 25° C. to 65° C. and the measurement atmosphere is humidified from 10% RH to 90% RH. be.
(iv) The resin layer has a linear expansion coefficient α2 of 300×10 ^-6 /K or less when the resin layer is heated from 25° C. to 85° C. and the measurement atmosphere is humidified from 10% RH to 85% RH. be.
(v) The dipole moment D of the monomer for forming the polymer is 2 Debye or less.

According to the present invention, it is possible to provide a polarizing film that can sufficiently suppress transmission of iodine contained in a polarizer to the outside in a high temperature and high humidity environment.

1 is a schematic cross-sectional view of a polarizing film according to an embodiment of the present invention. It is a schematic sectional view showing a modification of a polarizing film. It is a schematic sectional view showing another modification of a polarizing film. It is a schematic sectional view showing yet another modification of a polarizing film. 1 is a schematic cross-sectional view of an image display device according to an embodiment of the present invention.

The details of the present invention will be described below, but the following description is not intended to limit the present invention to specific embodiments.

(Embodiment of polarizing film)
As shown in FIG. 1, the polarizing film 10 of this embodiment includes a polarizer 1 containing iodine and a resin layer 2 containing a polymer P. For example, the resin layer 2 is located on the viewing side of the polarizer 1 and is in direct contact with the polarizer 1. However, other layers such as an adhesive layer and an easily adhesive layer may be disposed between the resin layer 2 and the polarizer 1 as long as the effects of the present invention are not impaired. The resin layer 2 may be located closer to the image display panel described later than the polarizer 1. In other words, the polarizer 1 may be located closer to the viewing side than the resin layer 2 is. The resin layer 2 is located, for example, at the outermost side of the polarizing film 10. Note that in this specification, the term "film" refers to a member whose thickness is sufficiently smaller than its length and width.

The polarizing film 10 may further include an adhesive layer 3, a transparent protective film (first transparent protective film) 4, and an adhesive layer 5. The transparent protective film 4 is bonded to the polarizer 1 via the adhesive layer 3, for example. The adhesive layer 5 functions, for example, as a member for bonding the polarizing film 10 to an image display panel to be described later. Therefore, the adhesive layer 5 is located, for example, at the outermost side of the polarizing film 10 and closer to the image display panel than the polarizer 1 is. In other words, the polarizer 1 is located closer to the viewing side than the adhesive layer 5, for example. For example, the resin layer 2, polarizer 1, adhesive layer 3, transparent protective film 4, and adhesive layer 5 are arranged in this order in the lamination direction.

In the polarizing film 10 of this embodiment, at least one of the following requirements (i) to (v) is satisfied, and preferably requirement (iii) is satisfied. In the polarizing film 10, all of requirements (i) to (v) may be satisfied.
(i) The tensile storage modulus E1 of the resin layer 2 at 65° C. in water is 1×10 ⁸ Pa or more.
(ii) The tensile storage modulus E2 of the resin layer 2 at 85° C. in water is 1×10 ⁸ Pa or more.
(iii) The linear expansion coefficient α1 of the resin layer 2 is 400×10 ^-6 /K or less when the resin layer 2 is heated from 25°C to 65°C and the measurement atmosphere is humidified from 10% RH to 90% RH. be.
(iv) The linear expansion coefficient α2 of the resin layer 2 is 300×10 ^-6 /K or less when the resin layer 2 is heated from 25°C to 85°C and the measurement atmosphere is humidified from 10% RH to 85% RH. be.
(v) The dipole moment D of the monomer M for forming the polymer P contained in the resin layer 2 is 2 Debye or less.

First, requirement (i) will be explained. The tensile storage modulus E1 of the resin layer 2 is preferably 5×10 ⁸ Pa or more, more preferably 10×10 ⁸ Pa or more, and even more preferably 15×10 ⁸ Pa or more. The upper limit of the tensile storage modulus E1 is not particularly limited, but may be, for example, 100×10 ⁸ Pa from the viewpoint of suppressing cracks in the resin layer 2.

The tensile storage modulus E1 of the resin layer 2 can be measured, for example, by the following method. First, the resin layer 2 to be evaluated is cut into a strip having a width of 5 mm and a length of 30 mm to form a test piece. Next, the test piece is set in a commercially available dynamic viscoelasticity measurement device. At this time, a jig that allows the test piece to be immersed in the solvent is used. The distance between the clamps that secure the specimen is set to 15 mm. Next, the test piece is immersed in water. After confirming that the temperature of the test piece is 25°C, measurement of dynamic viscoelasticity of the test piece is started. The measurement is performed by the tensile vibration-non-resonance method specified in Japanese Industrial Standards (JIS) K7244-4:1999. The frequency of vibration is set to 1 Hz. After starting the measurement, the test piece is heated to 95°C at a heating rate of 5°C/min. The measured value of the tensile storage modulus when the temperature of the test piece is 65° C. can be regarded as the tensile storage modulus E1 of the resin layer 2.

Next, requirement (ii) will be explained. The tensile storage modulus E2 of the resin layer 2 is preferably 5×10 ⁸ Pa or more, more preferably 10×10 ⁸ Pa or more, and even more preferably 15×10 ⁸ Pa or more. The upper limit of the tensile storage modulus E2 is not particularly limited, but may be, for example, 100×10 ⁸ Pa from the viewpoint of suppressing cracks in the resin layer 2. The tensile storage modulus E2 of the resin layer 2 can be measured, for example, by the same method as the tensile storage modulus E1. In detail, the dynamic viscoelasticity of the test piece was measured using the method described above for the tensile storage modulus E1, and the measured value of the tensile storage modulus when the temperature of the test piece was 85°C was calculated using the method described above for the tensile storage modulus E1. It can be regarded as the tensile storage modulus E2.

Next, requirement (iii) will be explained. The linear expansion coefficient α1 of the resin layer 2 is preferably 200×10 ⁻⁶ /K or less, more preferably 180×10 ⁻⁶ /K or less, and even more preferably 150×10 ⁻⁶ /K or less. , particularly preferably 120×10 ⁻⁶ /K or less. The lower limit value of the coefficient of linear expansion α1 is not particularly limited, but may be, for example, 10×10 ⁻⁶ /K from the viewpoint of suppressing cracks in the resin layer 2.

The linear expansion coefficient α1 of the resin layer 2 can be measured, for example, by the following method. First, the resin layer 2 to be evaluated is cut into a strip having a width of 5 mm and a length of 30 mm to form a test piece. Next, the test piece is set in a commercially available thermomechanical analyzer. At this time, the distance between the clamps for fixing the test piece is set to 15 mm. The test piece is left in a measurement atmosphere of 25° C. and 10% RH for at least 10 minutes. Next, the test piece is heated to 65° C. over 60 minutes, and the test piece is held for 10 minutes. Next, the measurement atmosphere is humidified from 10% RH to 90% RH over 30 minutes, and the test piece is held for 10 minutes. Based on the amount of change ΔL (mm) in the length of the test piece before and after the test, the linear expansion coefficient α calculated from the following formula (1) can be regarded as the linear expansion coefficient α1 of the resin layer 2. Note that in equation (1), L ₀ means the length of the test piece at 25° C., and ΔT means the amount of change in temperature of the test piece before and after the test. In requirement (iii), ΔT is 40°C.
Linear expansion coefficient α=ΔL/(L ₀ ×ΔT) (1)

Next, requirement (iv) will be explained. The linear expansion coefficient α2 of the resin layer 2 is preferably 200×10 ⁻⁶ /K or less, more preferably 170×10 ⁻⁶ /K or less, and even more preferably 150×10 ⁻⁶ /K or less. , particularly preferably 100×10 ⁻⁶ /K or less. The lower limit value of the coefficient of linear expansion α2 is not particularly limited, but may be, for example, 10×10 ⁻⁶ /K from the viewpoint of suppressing cracks in the resin layer 2. The linear expansion coefficient α2 of the resin layer 2 is, for example, except for heating the test piece to 85° C. over 60 minutes and humidifying the measurement atmosphere from 10% RH to 85% RH over 30 minutes. It can be measured by the same method as the linear expansion coefficient α1 described above. In requirement (iv), ΔT in the above formula (1) is 60°C.

Next, requirement (v) will be explained. The dipole moment D of the monomer M for forming the polymer P is preferably 1.7 Debye or less, more preferably 1.5 Debye or less, and still more preferably 1.3 Debye or less. The lower limit value of the dipole moment D is not particularly limited, and is, for example, 0.5 Debye.

The dipole moment D can be calculated, for example, by the following method. First, monomer M for forming polymer P is specified. For the monomer M, the dipole moment D can be calculated by performing a molecular simulation. Molecular simulation can be performed using known software such as Materials Studio (manufactured by BIOVIA, ver. 8.0.0.843) and WebMO (ver. 19.0.009e).

Calculation of the dipole moment D by molecular simulation can be performed, for example, by the following method. First, a molecular model of monomer M is created using Materials Studio. Regarding the molecular model, the structure is optimized by employing the force field of COMPASS (Condensed-phase Optimized Molecular Potentials for Atomistic Simulation Studies) II. Next, the molecular model of monomer M is processed with WebMO. Specifically, in WebMO, structure optimization calculations are performed on the molecular model of monomer M using the Gaussian program (Queue: g09). At this time, B3LYP may be used as the functional, and 6-31G(d) may be used as the basis function. Thereby, the dipole moment D of the monomer M can be calculated.

When the polymer P is formed from multiple types of monomers M, the dipole moment D can be specified by the following method. First, the dipole moment is calculated for each of the plurality of types of monomers M by the method described above. The calculated dipole moments are weighted by the molar ratio of each monomer M, and a weighted average is performed. The obtained weighted average value can be regarded as the dipole moment D. Even when multiple types of monomers M are structural isomers, the dipole moment D can be calculated by weighting the calculated dipole moments by the molar ratio of each structural isomer and performing a weighted average. can.

When at least one of requirements (i) and (ii) is satisfied, the polymer P contained in the resin layer 2 tends to maintain low molecular mobility even in a high temperature and high humidity environment. When the molecular mobility of the polymer P is low, it is difficult to create a space in the resin layer 2 into which iodine can enter. Thereby, movement of iodine from the polarizer 1 to the resin layer 2 is suppressed, and transmission of iodine to the outside of the polarizing film 10 can be suppressed.

When at least one of requirements (iii) and (iv) is satisfied, the polymer P contained in the resin layer 2 tends to maintain a small free volume even in a high temperature and high humidity environment. When the free volume of the polymer P is small, it is difficult to create a space in the resin layer 2 into which iodine can enter. Thereby, movement of iodine from the polarizer 1 to the resin layer 2 is suppressed, and transmission of iodine to the outside of the polarizing film 10 can be suppressed.

When requirement (v) is satisfied, electrostatic interaction tends to be less likely to occur between the polymer P and iodine. That is, iodine is less likely to be attracted to the polymer P. Thereby, movement of iodine from the polarizer 1 to the resin layer 2 is suppressed, and transmission of iodine to the outside of the polarizing film 10 can be suppressed.

In the polarizing film 10 of this embodiment, the value of y calculated by the following formula (2) may be less than 1.3.
y=(0.279)x ₁ +(-1.51)x ₂ +(0.178)x ₃ +0.386 (2)

In formula (2), x ₁ is the number of rotatable bonds contained in the monomer M for forming the polymer P. x ₁ can be an index for predicting how much the molecular motion of the polymer P is restricted. In this specification, the term "rotatable bond" refers to a bond included in a ring structure among single bonds connecting heavy atoms, and a single bond connecting a heavy atom located at the terminal to another heavy atom. means something removed. The term "heavy atom" refers to atoms other than hydrogen atoms and helium atoms, and specifically includes heteroatoms such as nitrogen atoms and oxygen atoms, and carbon atoms. Specific examples of single bonds connecting heavy atoms are carbon-carbon bonds and carbon-heteroatom bonds. As an example, if the polymer P is formed from dimethylol-tricyclodecane diacrylate, the value of x ₁ is 8. The number of rotatable bonds may be calculated using software for calculating molecular descriptors. Examples of such software include Dragon (version 7.0) and alvaDesc.

When the polymer P is formed from multiple types of monomers M, the value of x ₁ can be specified by the following method. First, the number of rotatable bonds is calculated for each of the plurality of types of monomers M. The calculated number of rotatable bonds is weighted by the molar ratio of each monomer M to perform a weighted average. The obtained weighted average value can be regarded as x ₁ . In this embodiment, the value of x ₁ is not particularly limited, and is, for example, 2 to 20.

x ₂ is the number of reaction points contained in the monomer M for forming the polymer P. x ₂ can be an index for predicting how many gaps large enough to allow a low-molecular compound to pass exist in the polymer P. As used herein, "reactive site" means a polymerizable group or a crosslinkable group. Specific examples of these groups include groups having polymerizable double bonds such as (meth)acryloyl groups, and crosslinkable functional groups such as epoxy groups and oxetane groups. As an example, if the polymer P is formed from dimethylol-tricyclodecane diacrylate, the value of x ₂ is 2. The number of reaction points may be calculated using the software for calculating molecular descriptors described above.

When the polymer P is formed from multiple types of monomers M, the value of x ₂ can be specified by the following method. First, the number of reaction points is calculated for each of the plurality of types of monomers M. The calculated number of reaction points is weighted by the molar ratio of each monomer M to perform a weighted average. The obtained weighted average value can be regarded as _x2 . In this embodiment, the value of x ₂ is not particularly limited, and is, for example, 1 to 6.

x ₃ is the polarization term δP (MPa ^1/2 ) in the Hansen solubility parameter of the monomer M to form the polymer P. x ₃ can serve as an index for predicting the interaction that occurs between the polymer P and water molecules or iodine. The Hansen solubility parameter is a solubility parameter introduced by Hildebrand divided into three components: a dispersion term δD, a polarization term δP, and a hydrogen bond term δH. The polarization term δP indicates energy due to dipole interaction between molecules. Details of Hansen solubility parameters are disclosed in "Hansen Solubility Parameters; A Users Handbook (CRC Press, 2007)". The polarization term δP can be calculated using known software such as HSPiP (version 5), for example. Note that the value of the polarization term δP may differ slightly depending on the software used. However, this error is usually so large that it can be ignored when calculating the value of y.

When the polymer P is formed from multiple types of monomers M, the value of x ₃ can be specified by the following method. First, for each of the plurality of types of monomers M, the polarization term δP (MPa ^1/2 ) in the Hansen solubility parameter is calculated. The calculated polarization term δP is weighted by the molar ratio of each monomer M, and a weighted average is performed. The obtained weighted average value can be regarded as _x3 . In this embodiment, the value of x ₃ is not particularly limited, and is, for example, 1 to 10 (MPa ^1/2 ). The value of x ₃ is preferably 6 (MPa ^1/2 ) or less, more preferably 5 (MPa ^1/2 ) or less, and even more preferably 4 (MPa ^1/2 ) or less.

The value of y calculated by formula (2) is preferably 0.8 or less, more preferably 0.7 or less, even more preferably 0.5 or less, and particularly preferably 0.3 or less. be.

The value of y calculated by formula (2) is an index regarding the monomer M for forming the polymer P included in the resin layer 2. However, according to the studies of the present inventors, the value of y is also useful as an index for selecting the resin layer 2 suitable for suppressing the transmission of iodine contained in the polarizer 1 to the outside. The value of y is particularly suitable as an index for predicting the characteristics of a resin layer containing a polymer having a structural unit derived from a (meth)acrylic acid ester.

[Polarizer]
The polarizer 1 is not particularly limited as long as it contains iodine. For example, it may be a hydrophilic polymer film such as a polyvinyl alcohol film, a partially formalized polyvinyl alcohol film, or a partially saponified ethylene/vinyl acetate copolymer film. Examples include those obtained by adsorbing iodine and uniaxially stretching. The polarizer 1 is preferably composed of a polyvinyl alcohol film and iodine.

The thickness of the polarizer 1 is not particularly limited, and is, for example, 30 μm or less, preferably 20 μm or less, more preferably 18 μm or less, even more preferably 15 μm or less, particularly preferably 12 μm or less, Particularly preferably, it is 10 μm or less. The thickness of the polarizer 1 may be 2 μm or more, 4 μm or more, or 5 μm or more. The thickness of the polarizer 1 may be 7 to 12 μm, in some cases 1 to 7 μm, especially 4 to 6 μm. In this specification, the polarizer 1 having a thickness of 10 μm or less may be referred to as a thin polarizer. Thin polarizers tend to have less uneven thickness and better visibility. Furthermore, the thin polarizer also has the advantage that dimensional changes are suppressed and it has excellent durability. According to the thin polarizer, the polarizing film 10 can be made thinner. When the polarizer 1 is a thin polarizer, it is necessary to adjust the concentration of iodine in the polarizer 1 to be high in order for the polarizing film 10 to have a practically sufficient degree of polarization. In the polarizing film 10 of this embodiment, even when the thickness of the polarizer 1 is small and the concentration of iodine in the polarizer 1 is high, it is possible to sufficiently suppress transmission of iodine from the polarizer 1 to the outside. I can do it.

The polarizer 1 can be produced, for example, by dyeing a hydrophilic polymer film such as a polyvinyl alcohol film by immersing it in an aqueous solution of iodine, and stretching the film to 3 to 7 times its original length. The hydrophilic polymer film may be immersed in an aqueous solution containing boric acid, potassium iodide, etc., if necessary. Furthermore, if necessary, the hydrophilic polymer film may be immersed in water and washed before dyeing. By washing the hydrophilic polymer film with water, dirt and anti-blocking agent adhering to the surface can be removed. When a hydrophilic polymer film is washed with water, it swells, which also has the effect of suppressing uneven dyeing. Stretching of the hydrophilic polymer film may be carried out after dyeing with iodine, may be carried out while dyeing, or may be carried out before dyeing with iodine. The hydrophilic polymer film may be stretched in an aqueous solution containing boric acid, potassium iodide, etc., or in water.

As a thin polarizer, typically, JP-A-51-069644, JP-A 2000-338329, WO 2010/100917, JP-A 2014-59328, and JP-A 2012-73563 are used. Examples include those described in . These thin polarizers are produced by a manufacturing method that includes a step of stretching a laminate including a polyvinyl alcohol resin (PVA resin) layer and a resin base material for stretching, and a step of dyeing the obtained stretched film. can. In this manufacturing method, since the PVA-based resin layer is supported by the stretching resin base material, defects such as breakage due to stretching are less likely to occur.

Among the above manufacturing methods, it is preferable that the thin polarizer be manufactured by a manufacturing method that includes a stretching step in a boric acid aqueous solution, from the viewpoint that it can be stretched at a high magnification and the polarization performance can be improved. In particular, it is preferable that the film be produced by a manufacturing method including a step of performing auxiliary aerial stretching before the stretching step in a boric acid aqueous solution. A manufacturing method including a stretching step in an aqueous boric acid solution is disclosed in WO 2010/100917, JP 2014-59328, JP 2012-73563, and the like. A manufacturing method including a step of performing aerial stretching is disclosed in JP-A No. 2014-59328, JP-A No. 2012-73563, and the like.

[Resin layer]
As long as at least one of the requirements (i) to (v) described above is satisfied, the resin layer 2 and the polymer P contained in the resin layer 2 are not particularly limited. The polymer P includes, for example, a structural unit derived from one monomer selected from the group consisting of a radically polymerizable monomer, a cationically polymerizable monomer, and an anionically polymerizable monomer, preferably a structural unit derived from a radically polymerizable monomer. include. The polymer P may include a structural unit derived from a radically polymerizable monomer and a structural unit derived from a cationically polymerizable monomer.

Examples of radically polymerizable monomers include (meth)acrylic acid esters and styrene compounds. As used herein, "(meth)acrylic acid" means acrylic acid and/or methacrylic acid.

The (meth)acrylic ester may be a monofunctional (meth)acrylic ester having one (meth)acryloyl group, or a polyfunctional (meth)acrylic ester having two or more (meth)acryloyl groups. It may be. It is preferable that the polymer P contains a structural unit derived from a polyfunctional (meth)acrylic acid ester. According to the polymer P containing a structural unit derived from a polyfunctional (meth)acrylic acid ester, there is a tendency that migration of iodine from the polarizer 1 to the resin layer 2 can be further suppressed. The number of (meth)acryloyl groups contained in the polyfunctional (meth)acrylic ester is not particularly limited, and is, for example, 2 to 6, preferably 2 to 4. When the number of (meth)acryloyl groups contained in the polyfunctional (meth)acrylic acid ester is too large, unreacted (meth)acryloyl groups may remain in the polymer P.

The number of carbon atoms in the moiety other than the (meth)acryloyl group (hereinafter sometimes referred to as ester moiety) in the (meth)acrylic ester is not particularly limited, and is, for example, from 1 to 18, preferably from 4 to 10. . The ester moiety may include a ring structure. The ring structure may contain a heteroatom such as a nitrogen atom or an oxygen atom, but is preferably composed only of alicyclic hydrocarbons. The ring structure may be a fused ring structure such as tricyclodecane or a monocyclic structure such as cyclohexane. The ester moiety may contain a functional group such as an ether group.

The (meth)acrylic acid ester may contain a polar group, but preferably does not contain a polar group. In this specification, a polar group means a group containing a bond between a hydrogen atom and a heteroatom such as an oxygen atom or a nitrogen atom. Examples of the polar group include a hydroxyl group, a carboxyl group, a primary amine group, and a secondary amine group.

(Meth)acrylic acid esters include, for example, dicyclopentanyl (meth)acrylate, 4-t-butylcyclohexyl (meth)acrylate, lauryl (meth)acrylate, 5-(meth)acryloxy-2,6-norbornane. Carboractone, 3,3,5-trimethylcyclohexyl (meth)acrylate, 4-t-butylphenyl (meth)acrylate, isobornyl (meth)acrylate, 1-adamantyl (meth)acrylate, 2-adamantyl (meth)acrylate, 2 -Methyl-2-adamantyl (meth)acrylate, 2-ethyl-2-adamantyl (meth)acrylate, 2-isopropyl-2-adamantyl (meth)acrylate, 4-biphenyl (meth)acrylate, 1-naphthyl (meth)acrylate , 2-naphthyl (meth)acrylate, 1-anthracene (meth)acrylate, 1-anthracenemethyl (meth)acrylate, 9-anthracenemethyl (meth)acrylate; monofunctional (meth)acrylic acid ester; dimethylol-tricyclode Kandi(meth)acrylate, 1,3-adamantanediol di(meth)acrylate, 1,3,5-adamantanetriol-1,5-di(meth)acrylate, 9,9-bis[4-(2-(meth)acrylate ) difunctional (meth)acrylic acid esters such as acryloyloxyethoxy)phenyl)fluorene; trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, 1,3,5-adamantanetrioltri(meth)acrylate, etc. Examples include trifunctional (meth)acrylic esters; tetrafunctional (meth)acrylic esters such as pentaerythritol tetra(meth)acrylate; and hexafunctional (meth)acrylic esters such as dipentaerythritol hexa(meth)acrylate.

Styrenic compounds include, for example, an aromatic ring and one or more vinyl groups. Like the (meth)acrylic ester, the styrene compound may contain a polar group, but preferably does not contain a polar group. Examples of the styrene compound include styrene, α-methylstyrene, vinylbenzyl chloride, butoxystyrene, and vinylpyridine.

The polymer P preferably contains as a main component a structural unit derived from a radically polymerizable monomer, and preferably consists essentially of structural units derived from a radically polymerizable monomer. In this specification, the "main component" means the structural unit that is contained in the polymer P in the largest amount on a weight basis. In particular, the polymer P preferably contains a structural unit derived from (meth)acrylic acid ester, and the content thereof is, for example, 50% by weight or more, preferably higher than 70% by weight, and more preferably 80% by weight. % or more, more preferably 90% by weight or more, particularly preferably 95% by weight or more, particularly preferably 99% by weight or more.

Examples of the cationically polymerizable monomer include vinyl ether compounds, epoxy compounds, and oxetane compounds. Examples of vinyl ether compounds include aliphatic vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, butyl vinyl ether, and cyclohexyl vinyl ether; aromatic vinyl ethers such as phenyl vinyl ether, 2-phenoxyethyl vinyl ether, and p-methoxyphenyl vinyl ether; butanediol-1, 4 - Polyfunctional vinyl ethers such as divinyl ether, triethylene glycol divinyl ether, and dipropylene glycol divinyl ether.

Examples of the epoxy compound include aromatic epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds. Examples of aromatic epoxy compounds include diglycidyl ether compounds of bisphenols (bisphenol type epoxy resins) such as bisphenol A, bisphenol F , and bisphenol S; phenol novolac epoxy resins, cresol novolac epoxy resins, and hydroxybenzaldehydephenol novolac epoxy resins. Novolak type epoxy resin; examples include glycidyl ether compounds of polyalcohols such as tetrahydroxyphenylmethane, tetrahydroxybenzophenone, and polyvinylphenol.

Examples of the alicyclic epoxy compound include vinylcyclohexene dioxide, 3',4'-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, limonene dioxide, bis(3,4-epoxycyclohexylmethyl)adipate, Dicyclopentadiene diepoxide, bicyclononadiene diepoxide, tricyclopentadiene diepoxide, dodecahydro-2,6-methano-2H-oxilano[3',4']cyclopenta[1',2':6,7]nafs[ 2,3-b]oxirane and the like.

Examples of aliphatic epoxy compounds include 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerol triglycidyl ether, trimethylolpropane triglycidyl ether, ethylene glycol diglycidyl ether, and propylene glycol diglycidyl ether. , neopentyl glycol diglycidyl ether, polyethylene glycol diglycidyl ether, and the like.

Oxetane compounds include 3-ethyl-3-hydroxymethyloxetane, 1,4-bis[(3-ethyl-3-oxetanyl)methoxymethyl]benzene, 3-ethyl-3-(phenoxymethyl)oxetane, bis[( Examples thereof include 3-ethyl-3-oxetanyl)methyl]ether and 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane.

Examples of anionically polymerizable monomers include (meth)acrylic esters. As the (meth)acrylic ester as the anionically polymerizable monomer, those mentioned above as the radically polymerizable monomer can be used.

It is preferable that the polymer P contains a structural unit derived from a polyfunctional monomer. Examples of the polyfunctional monomer include the aforementioned polyfunctional (meth)acrylic acid ester, polyfunctional vinyl ether compound, polyfunctional epoxy compound, polyfunctional oxetane compound, and the like. The content of structural units derived from polyfunctional monomers in the polymer P is, for example, 20% by weight or more, preferably 40% by weight or more, more preferably 50% by weight or more, and in some cases 70% by weight. It may be more than that. The upper limit of the content of structural units derived from polyfunctional monomers is not particularly limited, and is, for example, 95% by weight.

The polymer P may contain a structural unit derived from a monomer having a polar group, but preferably does not contain it. When the polymer P contains a structural unit derived from a monomer having a polar group, iodine contained in the polarizer 1 tends to approach the resin layer 2 easily. Therefore, the content of structural units derived from monomers having polar groups in the polymer P is preferably 20% by weight or less, more preferably 10% by weight or less, still more preferably 5% by weight or less, Particularly preferably, it is 2% by weight or less.

The resin layer 2 contains, for example, a polymer P as a main component. The content of the polymer P in the resin layer 2 is, for example, 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more, and even more preferably 95% by weight or more. The resin layer 2 preferably consists essentially of the polymer P only. However, in addition to the polymer P, the resin layer 2 may contain additives such as an antistatic agent, an antioxidant, inorganic particles, and a leveling agent.

The thickness of the resin layer 2 is not particularly limited, and is, for example, 10 μm or less, preferably 5 μm or less, and more preferably 3 μm or less. The thickness of the resin layer 2 is preferably 0.3 μm or more, and may be 0.5 μm or more, from the viewpoint of sufficiently suppressing the transmission of iodine contained in the polarizer 1 to the outside.

The resin layer 2 may be bonded to the polarizer 1 via an adhesive layer or an easily adhesive layer. Examples of the adhesive layer for bonding the resin layer 2 to the polarizer 1 include those exemplified for the adhesive layer 3 described later. The easily adhesive layer can be formed of a resin containing a polymer having a polyester skeleton, a polyether skeleton, a polycarbonate skeleton, a polyurethane skeleton, a silicone system, a polyamide skeleton, a polyimide skeleton, a polyvinyl alcohol skeleton, etc., for example. The number of polymers contained in the resin may be one, or two or more. The easily adhesive layer may contain an additive. Examples of additives include tackifiers, ultraviolet absorbers, antioxidants, stabilizers such as heat stabilizers, and the like. The thickness of the easily adhesive layer is not particularly limited, and is preferably 0.01 to 5 μm, more preferably 0.02 to 2 μm, and even more preferably 0.05 to 1 μm. The easily adhesive layer may be a laminate of multiple layers.

[Adhesive layer]
The adhesive layer 3 is a layer containing an adhesive. The material of the adhesive is not particularly limited, and known materials can be used. Examples of the adhesive included in the adhesive layer 3 include a water-based adhesive and an active energy ray-curable adhesive. As the active energy ray curable adhesive, for example, those disclosed in JP-A-2019-147865, JP-A-2016-177248, etc. can be used.

The thickness of the adhesive layer 3 is not particularly limited, and is, for example, 3.0 μm or less, preferably 0.01 to 3.0 μm, more preferably 0.1 to 2.5 μm, and even more preferably It is 0.5 to 1.5 μm. If the thickness of the adhesive layer 3 is too small, the cohesive force of the adhesive layer 3 may be insufficient and the peeling force may decrease. If the thickness of the adhesive layer 3 is too large and stress is applied to the cross section of the polarizing film 10, peeling may occur in the adhesive layer 3. That is, in the polarizing film 10, peeling defects may occur due to impact.

[Transparent protective film]
The transparent protective film 4 is preferably one that has excellent transparency, mechanical strength, thermal stability, moisture barrier properties, isotropy, and the like. Examples of materials for the transparent protective film 4 include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate; cellulose polymers such as diacetyl cellulose and triacetyl cellulose; (meth)acrylic polymers such as polymethyl methacrylate; polystyrene and acrylonitrile.・Styrenic polymers such as styrene copolymers (AS resins); Polycarbonate polymers; Olefin polymers such as polyethylene, polypropylene, and ethylene-propylene copolymers; Cyclic olefin polymers such as polynorbornene; Vinyl chloride polymers; Nylon , amide polymers such as aromatic polyamide; imide polymers; sulfone polymers; polyether sulfone polymers; polyetheretherketone polymers; polyphenylene sulfide polymers; vinyl alcohol polymers; vinylidene chloride polymers; vinyl butyral polymers ; arylate polymers; polyoxymethylene polymers; epoxy polymers; mixtures of these polymers, and the like.

It is preferable that the transparent protective film 4 contains a polymer that functions as a thermoplastic resin among the above-mentioned polymers. The content of the thermoplastic resin in the transparent protective film 4 is preferably 50% to 100% by weight, more preferably 50% to 99% by weight, even more preferably 60% to 98% by weight. , particularly preferably from 70% to 97% by weight. When the content of the thermoplastic resin in the transparent protective film 4 is less than 50% by weight, functions such as high transparency inherent to the thermoplastic resin may not be fully expressed.

The transparent protective film may contain one or more types of additives. Examples of additives include ultraviolet absorbers, antioxidants, lubricants, plasticizers, mold release agents, color inhibitors, flame retardants, nucleating agents, antistatic agents, pigments, and colorants.

The transparent protective film 4 may be a polymer film described in JP-A No. 2001-343529, International Publication No. 01/37007, and the like. Materials for this polymer film include, for example, thermoplastic resins having substituted and/or unsubstituted imide groups in their side chains, and thermoplastic resins having substituted and/or unsubstituted phenyl groups and nitrile groups in their side chains. Examples include resin compositions containing the following. A specific example of this polymer film is a film formed from a resin composition containing an alternating copolymer of isobutylene and N-methylmaleimide and an acrylonitrile-styrene copolymer. This film can be obtained, for example, by mixing and extruding a resin composition. Since this film has a small retardation and a small photoelastic coefficient, it is possible to eliminate problems such as unevenness due to distortion of the polarizing film 10. Furthermore, this film has low moisture permeability, so it has excellent durability in humid environments.

The moisture permeability of the transparent protective film 4 is not particularly limited, but is preferably 150 g/m ² /24 h or less. In this case, it is possible to suppress moisture in the air from entering the inside of the polarizing film 10, and it is possible to suppress a change in the moisture content of the polarizing film 10. Thereby, it is possible to suppress the occurrence of curling or dimensional changes in the polarizing film 10 during storage or the like. Examples of materials forming the transparent protective film 4 with low moisture permeability include polyester polymers, polycarbonate polymers, arylate polymers, amide polymers, olefin polymers, cyclic olefin polymers, (meth)acrylic polymers, and Mixtures of these may be mentioned. As the material forming the transparent protective film 4, polycarbonate polymers, cyclic olefin polymers, and (meth)acrylic polymers are preferable, and cyclic olefin polymers and (meth)acrylic polymers are particularly preferable.

The thickness of the transparent protective film 4 is not particularly limited, but from the viewpoint of strength, handleability, etc., it is preferably 5 to 100 μm, more preferably 10 to 60 μm, and even more preferably 13 to 40 μm.

The surface of the transparent protective film 4 may be subjected to adhesion-facilitating treatment such as corona treatment or plasma treatment in order to improve the adhesion between members. An easily adhesive layer may be arranged on the surface of the transparent protective film 4. As the easily adhesive layer, those mentioned above for the resin layer 2 can be used.

[Adhesive layer]
The adhesive layer 5 is a layer containing an adhesive. The material of the adhesive is not particularly limited, and for example, a base polymer containing (meth)acrylic polymer, silicone polymer, polyester, polyurethane, polyamide, polyether, fluorine polymer, rubber polymer, etc. may be used. I can do it. In particular, acrylic adhesives containing (meth)acrylic polymers have excellent optical transparency, appropriate adhesive properties such as wettability, cohesiveness, and adhesiveness, and are excellent in weather resistance, heat resistance, etc. , suitable for the material of the adhesive layer 5.

The adhesive layer 5 may be a laminate of multiple layers having different compositions. The thickness of the adhesive layer 5 is appropriately determined depending on the purpose of use, adhesive strength, etc., and is, for example, 1 to 500 μm, preferably 1 to 200 μm, and more preferably 1 to 100 μm. The thickness of the adhesive layer 5 may be 50 μm or less.

The adhesive layer 5 may be bonded to a separator before the polarizing film 10 is bonded to the image display panel. According to the separator, contamination of the adhesive layer 5 can be prevented. As a separator, for example, thin films such as plastic films, rubber sheets, paper, cloth, nonwoven fabrics, nets, foam sheets, metal foils, and laminates thereof, silicone-based, long-chain alkyl-based, and fluorine-based separators may be used. A material coated with a release agent such as molybdenum sulfide can be used.

[Other parts]
The polarizing film 10 may further include members other than those described above. The polarizing film 10 may further include, for example, a transparent substrate located on the viewing side of the resin layer 2. A transparent substrate may be located at the outermost side of the polarizing film 10. The transparent substrate is made of glass or polymer, for example. Examples of the polymer constituting the transparent substrate include polyethylene terephthalate, polycycloolefin, and polycarbonate. The thickness of the transparent substrate made of glass is, for example, 0.1 mm to 1 mm. The thickness of the transparent substrate made of polymer is, for example, 10 μm to 200 μm.

The transparent substrate is bonded to the resin layer 2 via, for example, an optical clear adhesive (OCA) layer. As the OCA layer, for example, the one described above for the adhesive layer 5 can be used. The thickness of the OCA layer is preferably 150 μm or less.

The polarizing film 10 may further include an optical film such as a reflective plate, an anti-transmissive plate, a retardation film, a viewing angle compensation film, and a brightness enhancement film. The retardation film includes, for example, a 1/2 wavelength plate, a 1/4 wavelength plate, and the like. In the polarizing film 10, the retardation film may be disposed closer to the image display panel than the polarizer 1 (for example, between the adhesive layer 5 and the transparent protective film 4), and may be disposed closer to the viewing side than the polarizer 1. It may be placed in

The polarizing film 10 may further include functional layers such as a hard coat layer, an antireflection layer, an antisticking layer, a diffusion layer, and an antiglare layer. In the polarizing film 10, the hard coat layer may be placed closer to the viewer than the resin layer 2.

[Manufacturing method of polarizing film]
The polarizing film 10 can be produced, for example, by the following method. First, the polarizer 1 and the transparent protective film 4 are bonded together via the adhesive layer 3. Next, a coating liquid containing monomer M for forming polymer P and a polymerization initiator is prepared. The polymerization initiator can be appropriately selected depending on the monomer M contained in the coating liquid. As an example, when the coating liquid contains a radically polymerizable monomer, a photopolymerization initiator can be used as the polymerization initiator. When the coating liquid contains a cationically polymerizable monomer, a photoacid generator can be used as a polymerization initiator.

Examples of photopolymerization initiators include benzophenone compounds such as benzyl, benzophenone, benzoylbenzoic acid, and 3,3'-dimethyl-4-methoxybenzophenone; 4-(2-hydroxyethoxy)phenyl(2-hydroxy-2- Aromatic ketone compounds such as propyl) ketone, α-hydroxy-α, α'-dimethylacetophenone, 2-methyl-2-hydroxypropiophenone, α-hydroxycyclohexylphenyl ketone; methoxyacetophenone, 2,2-dimethoxy-2 - Acetophenone compounds such as phenylacetophenone, 2,2-diethoxyacetophenone, 2-methyl-1-[4-(methylthio)-phenyl]-2-morpholinopropan-1-one; benzoin methyl ether , benzoin ether compounds such as benzoin ethyl ether, benzoin isopropyl ether, benzoin butyl ether, and anisoin methyl ether; aromatic ketal compounds such as benzyl dimethyl ketal; aromatic sulfonyl compounds such as 2-naphthalenesulfonyl chloride Chloride compounds; photoactive oxime compounds such as 1-phenone-1,1-propanedione-2-(o-ethoxycarbonyl)oxime; thioxanthone, 2-chlorothioxanthone, 2-methylthioxanthone, 2,4-dimethylthioxanthone , isopropylthioxanthone, 2,4-dichlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, dodecylthioxanthone, and other thioxanthone compounds; camphorquinone; halogenated ketones; acylphosphinoxide; acyl phosphonate, etc. can be mentioned.

Examples of the photoacid generator include compounds represented by the following formula (i).
L ⁺ X ^- (i)

In formula (i), L ⁺ is an onium cation, and X ^- is PF ₆ ^- , SbF ₆ ^- , AsF ₆ ^{-, SbCl 6 -} _, ^BiCl ₅ ^- , SnCl ₆ ^- , ClO ₄ ^- , dithiocarbamate anion. and SCN ^- .

Specific examples of photoacid generators include "Cylacure UVI-6992", "Cylacure UVI-6974" (manufactured by Dow Chemical Japan Co., Ltd.), "ADEKA OPTOMER SP150", "ADEKA OPTOMER" "SP152", "ADEKA OPTOMER SP170", "ADEKA OPTOMER SP172" (manufactured by ADEKA Co., Ltd.), "IRGACURE250" (manufactured by Ciba Specialty Chemicals), "CI-5102", "CI-2855" (manufactured by Ciba Specialty Chemicals) , manufactured by Nippon Soda Co., Ltd.), "Sunaid SI-60L", "Sunaid SI-80L", "Sunaid SI-100L", "Sunaid SI-110L", "Sunaid SI-180L" (all manufactured by Sanshin Kagaku Co., Ltd.) , "CPI-100P", "CPI-100A" (manufactured by Sun-Apro Co., Ltd.), "WPI-069", "WPI-113", "WPI-116", "WPI-041", "WPI-044" , "WPI-054", "WPI-055", "WPAG-281", "WPAG-567", and "WPAG-596" (all manufactured by Wako Pure Chemical Industries, Ltd.).

The content of the polymerization initiator in the coating liquid is, for example, 20% by weight or less, preferably 0.01 to 20% by weight, more preferably 0.05 to 10% by weight, and even more preferably 0.1% by weight. ~5% by weight.

Next, a coating liquid is applied onto the polarizer 1. Thereby, a film (coating film) containing the monomer M and the polymerization initiator can be formed on the polarizer 1. Next, the monomer M is polymerized so that the resin layer 2 is formed from the coating film. Polymerization of monomer M can be performed by a known method. For example, when using a photopolymerization initiator or a photoacid generator as a polymerization initiator, the monomer M can be polymerized by irradiating the coating film with active energy rays. Examples of active energy rays include visible light and ultraviolet rays. In this specification, the resin layer 2 produced by polymerizing the monomer M contained in the coating film may be referred to as a cured resin layer. Next, a polarizing film 10 is obtained by bonding the adhesive layer 5 to the transparent protective film 4.

The resin layer 2 may be produced by the following method. First, monomer M is polymerized to obtain polymer P. The obtained polymer P is added to a solvent to prepare a coating liquid. Examples of the solvent include organic solvents that can dissolve or disperse the polymer P. Next, a coating film is produced by applying a coating liquid onto the polarizer 1. The resin layer 2 is obtained by drying the coating film.

[Characteristics of polarizing film]
In the polarizing film 10 of the present embodiment, at least one of the above requirements (i) to (v) is satisfied, so that the iodine contained in the polarizer 1 is sufficiently transmitted to the outside in a high temperature and humid environment. suppressed. That is, under a high temperature and high humidity environment, the concentration of iodine in the polarizer 1 hardly changes. Changes in the iodine concentration in the polarizer 1 can be read from changes in the single transmittance of the polarizing film 10, for example. As an example, when the polarizing film 10 is bonded to non-alkali glass via the adhesive layer 5 and placed in an atmosphere of 65° C. and 90% RH for 24 hours, the individual transmission of the polarizing film 10 is The rate change ΔY1 is, for example, 5 or less, preferably 4 or less, more preferably 2 or less, still more preferably 1.5 or less, particularly preferably 1 or less.

Specifically, the change ΔY1 in single transmittance can be measured by the following method. First, the single transmittance Ts1 of the laminate obtained by bonding the polarizing film 10 to alkali-free glass via the adhesive layer 5 is measured. Next, this laminate is placed in an atmosphere of 65° C. and 90% RH for 24 hours. After placing the laminate in this atmosphere, the single transmittance Ts2 is measured. The value obtained by subtracting the single transmittance Ts1 from the single transmittance Ts2 is regarded as the change ΔY1 in the single transmittance. Note that the single transmittance of the laminate is the Y value corrected for visibility using the 2-degree field of view (C light source) of JIS Z8701-1999. Single transmittance can be measured using a commercially available spectrophotometer such as DOT-3 manufactured by Murakami Color Research Institute. The measurement wavelength of single transmittance is 380 to 700 nm (every 10 nm). Alkali-free glass is glass that does not substantially contain an alkali component (alkali metal oxide), and specifically, the weight ratio of the alkali component in the glass is, for example, 1000 ppm or less, and further 500 ppm or less. The alkali-free glass is, for example, plate-shaped and has a thickness of 0.5 mm or more.

The single transmittance Ts1 is not particularly limited, and is, for example, 42% to 46%, preferably 43% or more, and more preferably 44% or more. The single transmittance Ts2 is not particularly limited, and is, for example, 42% to 48%, preferably 47% or less, and more preferably 46% or less.

(Modified example of polarizing film)
In the polarizing film 10, the resin layer 2 may be located closer to the image display panel described later than the polarizer 1. As shown in FIG. 2, in the polarizing film 11 according to this modification, the resin layer 2 is located closer to the image display panel than the polarizer 1 is. Except for the position of the resin layer 2, the structure of the polarizing film 11 is the same as that of the polarizing film 10. Therefore, elements that are common between the polarizing film 10 and the modified polarizing film 11 are given the same reference numerals, and their descriptions may be omitted. That is, the following descriptions regarding each embodiment are mutually applicable unless technically inconsistent. The following embodiments may be combined with each other unless technically inconsistent.

For example, the resin layer 2 is located between the polarizer 1 and the adhesive layer 3, and is in direct contact with each of the polarizer 1 and the adhesive layer 3. However, other layers such as an adhesive layer and an easily bonding layer may be arranged between the resin layer 2 and the polarizer 1. For example, the resin layer 2 may be bonded to the polarizer 1 via an adhesive layer or an easily adhesive layer. As the adhesive layer and the easily adhesive layer for bonding the resin layer 2 to the polarizer 1, those mentioned above for the polarizing film 10 can be mentioned. When the resin layer 2 is located closer to the image display panel than the polarizer 1, iodine contained in the polarizer 1 moves to the adhesive layer 5 in a high temperature and humid environment, and is transferred to the polarizing film 11 through the adhesive layer 5. Transmission to the outside can be suppressed.

(Another modification of polarizing film)
The polarizing film 10 may further include members other than those described above. As shown in FIG. 3, the polarizing film 12 according to this modification further includes a transparent protective film (second transparent protective film) 6. Except for the second transparent protective film 6, the structure of the polarizing film 12 is the same as that of the polarizing film 10. Therefore, common elements between the polarizing film 10 and the modified polarizing film 12 are given the same reference numerals, and their descriptions may be omitted.

The second transparent protective film 6 is located closer to the viewing side than the polarizer 1. The polarizer 1 is located, for example, between the first transparent protective film 4 and the second transparent protective film 6. The second transparent protective film 6 is, for example, located closer to the viewer than the resin layer 2 and at the outermost side of the polarizing film 12. However, when the polarizing film 12 includes the above-mentioned transparent substrate, the second transparent protective film 6 may be located between the resin layer 2 and the transparent substrate. The second transparent protective film 6 is in direct contact with the resin layer 2, for example. However, the second transparent protective film 6 may be bonded to the resin layer 2 via another layer such as an adhesive layer or a hard coat layer. Examples of the adhesive layer for bonding the second transparent protective film 6 to the resin layer 2 include those described above for the adhesive layer 3.

As the second transparent protective film 6, those mentioned above for the first transparent protective film 4 can be used. The first transparent protective film 4 and the second transparent protective film 6 may be the same or different.

In the polarizing film 12 provided with the second transparent protective film 6, the transmission of iodine contained in the polarizer 1 to the outside tends to be more suppressed in a high temperature and high humidity environment. As an example, when the polarizing film 12 is attached to non-alkali glass via the adhesive layer 5 and the polarizing film 12 is placed in an atmosphere of 65° C. and 90% RH for 120 hours, the individual transmission of the polarizing film 12 is The rate change ΔY2 is, for example, 3 or less, preferably 2 or less, more preferably 1.5 or less, still more preferably 1 or less, particularly preferably 0.8 or less.

Specifically, the change ΔY2 in single transmittance can be measured by the following method. First, the single transmittance Ts3 of the laminate obtained by bonding the polarizing film 12 to alkali-free glass via the adhesive layer 5 is measured. Next, this laminate is placed in an atmosphere of 65° C. and 90% RH for 120 hours. After placing the laminate in this atmosphere, the single transmittance Ts4 is measured. The value obtained by subtracting the single transmittance Ts3 from the single transmittance Ts4 is regarded as the change ΔY2 in the single transmittance.

The single transmittance Ts3 is not particularly limited, and is, for example, 42% to 46%, preferably 43% or more, and more preferably 44% or more. The single transmittance Ts4 is not particularly limited, and is, for example, 42% to 48%, preferably 47% or less, and more preferably 46% or less.

(Yet another modification of polarizing film)
The polarizing film 10 may include two or more resin layers 2. As shown in FIG. 4, the polarizing film 13 according to this modification includes two resin layers 2a and 2b. The structure of the polarizing film 13 is the same as that of the polarizing film 10 except for the resin layer 2b. Therefore, common elements between the polarizing film 10 and the modified polarizing film 13 are given the same reference numerals, and their explanations may be omitted.

In the polarizing film 13, the polarizer 1 is located between the two resin layers 2a and 2b. Specifically, the resin layer 2b is located closer to the image display panel than the polarizer 1 (for example, between the polarizer 1 and the adhesive layer 3). When the polarizer 1 is arranged between the two resin layers 2a and 2b, in the polarizing film 13, the transmission of iodine contained in the polarizer 1 to the outside tends to be further suppressed.

The resin layer 2b may be in direct contact with the polarizer 1. However, other layers such as an adhesive layer and an easily adhesive layer may be arranged between the resin layer 2b and the polarizer 1. For example, the resin layer 2b may be bonded to the polarizer 1 via an adhesive layer or an easily adhesive layer. As the adhesive layer and the easily adhesive layer for bonding the resin layer 2b to the polarizer 1, those mentioned above for the polarizing film 10 can be mentioned.

(Embodiment of image display device)
As shown in FIG. 5, the image display device 100 of this embodiment includes a polarizing film 10 and an image display panel 20. In the image display device 100, a polarizing film 11, 12, or 13 can also be used instead of the polarizing film 10. In the image display device 100, the polarizing film 10 is bonded to the image display panel 20 via the adhesive layer 5, for example. Examples of the image display panel 20 include an organic EL display panel, a liquid crystal display panel, and the like, and preferably an organic EL display panel.

The image display device 100 further includes, for example, an illumination system (not shown). As an example, the polarizing film 10, the image display panel 20, and the illumination system are arranged in this order, with the polarizing film 10 being located on the most visible side. The illumination system includes, for example, a backlight or a reflector, and irradiates the image display panel 20 with light.

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

<Thin polarizer>
First, a laminate was prepared in which a 9 μm thick PVA layer was formed on an amorphous polyethylene terephthalate (PET) base material. This laminate was subjected to aerial auxiliary stretching at a stretching temperature of 130°C to produce a stretched laminate. Next, the stretched laminate was dyed using iodine to obtain a colored laminate. Furthermore, the colored laminate was stretched in a boric acid aqueous solution at a stretching temperature of 65 degrees to obtain a laminate in which the amorphous PET base material and the PVA layer were integrally stretched. In the laminate, the total stretching ratio was 5.94 times, and the thickness of the PVA layer was 5 μm. The PVA molecules of the PVA layer formed on the amorphous PET base material by the above two-stage stretching were highly oriented. Furthermore, the iodine adsorbed by dyeing was highly oriented in one direction as a polyiodine ion complex. The PVA layer included in the laminate functioned as a thin polarizer.

<Transparent protective film>
First, a resin composed of an imidized methyl methacrylate-styrene copolymer (imidized MS resin) was produced by the method described in Production Example 1 of JP-A-2010-284840. Next, using a twin-screw kneader, 100 parts by weight of the imidized MS resin and 0.62 parts by weight of a triazine-based ultraviolet absorber (manufactured by Adeka, trade name: T-712) were mixed at 220°C, and resin pellets were formed. was created. The obtained resin pellets were dried in an environment of 100.5 kPa and 100° C. for 12 hours. Next, a film with a thickness of 160 μm was produced by extruding the resin pellets from a T-die at a die temperature of 270° C. using a single-screw extruder. Furthermore, this film was stretched in the transport direction in an atmosphere at 150° C., and the thickness was adjusted to 80 μm. Next, after applying an easy-adhesive agent containing an aqueous urethane resin to the film, the film was stretched in an atmosphere at 150° C. in a direction perpendicular to the transport direction to obtain a transparent protective film with a thickness of 40 μm. The moisture permeability of this transparent protective film was 58 g/m ² /24 h.

<Active energy ray curable adhesive composition>
12 parts by weight of hydroxyethyl acrylamide (manufactured by KJ Chemicals, trade name: HEAA), 24 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate (manufactured by Toagosei Co., Ltd., trade name: ARONIX M-5700), 12 parts by weight of hydroxypivalic acid neopentyl glycol acrylic acid adduct (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate HPP-A), 38 parts by weight of 1,9-nonanediol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate) 1,9ND-A), 10 parts by weight of acrylic oligomer (manufactured by Toagosei Co., Ltd., trade name: ARUFON UP-1190), 3 parts by weight of 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropane- 1-one (manufactured by IGM Resins, trade name: OMNIRAD 907) and 2 parts by weight of 2,4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd., trade name: KAYACURE DETX-S) are mixed and stirred for 3 hours. Thus, an active energy ray-curable adhesive composition was obtained.

<Laminated body including transparent protective film, adhesive layer and thin polarizer>
Using an MCD coater manufactured by Fuji Kikai Co., Ltd. (cell shape: honeycomb, number of gravure rolls: 1000 rolls/inch, rotation speed 140%/to line speed), the active energy ray-curable adhesive composition was applied to a transparent protective film. Coated on the bonding surface. The thickness of the resulting coating film was 0.7 μm. Next, the transparent protective film and the laminate including the PVA layer were bonded together using a roll machine. At this time, the coating film and the PVA layer were brought into contact. The line speed of the roll machine was 25 m/min. Next, the obtained laminate was irradiated with active energy rays from the transparent protective film side. As the active energy ray, visible light emitted from a visible light irradiation device (Light HAMMER10 manufactured by Fusion UV Systems) was used. The light source of the visible light irradiation device was a gallium-filled metal halide lamp. In the visible light irradiation device, a V bulb was used as the bulb. The peak illuminance of the light emitted from the visible light irradiation device was 1600 mW/cm ² . In the wavelength range of 380 nm to 440 nm, the cumulative irradiation amount of the light emitted from the visible light irradiation device was 1000 mJ/cm ² . The illuminance of the light emitted from the visible light irradiation device was measured using a Sola-Check system manufactured by Solatell. By irradiating the laminate with active energy rays, the active energy ray-curable adhesive composition in the coating film was cured. Next, this laminate was dried with hot air at 70° C. for 3 minutes to obtain a laminate a including a transparent protective film, an adhesive layer, and a thin polarizer.

[Example 1]
(Polarizing film A)
First, 50 parts by weight of dicyclopentanyl acrylate (manufactured by Hitachi Chemical Co., Ltd., trade name: Fancryl FA-513AS), 50 parts by weight of dimethylol-tricyclodecane diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate DCP) -A), 2 parts by weight of 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (manufactured by IGM Resins, trade name: OMNIRAD 907) and 2 parts by weight of 2,4- A coating solution was prepared by mixing diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd., trade name: KAYACURE DETX-S).

Next, the amorphous PET base material adjacent to the PVA layer was removed from the laminate a. The above coating liquid was applied onto the exposed PVA layer using Select Roller #0 (manufactured by OSG System Products Co., Ltd.). The thickness of the resulting coating film was 1 μm. Next, the monomer was polymerized by irradiating the coating film with visible light under a nitrogen stream using the visible light irradiation device described above. The coating film was cured by polymerization of the monomer, and a resin layer was formed.

Next, the surface of the transparent protective film was subjected to corona treatment. A 20 μm thick adhesive layer was attached to this surface. The adhesive layer was composed of an acrylic adhesive. Thereby, a polarizing film A was obtained which included a resin layer, a polarizer, an adhesive layer, a transparent protective film, and an adhesive layer in this order.

(Polarizing film B)
First, a coating liquid was prepared using the same method as for polarizing film A. Lamination of a 20 μm thick triacetyl cellulose (TAC) film using an MCD coater manufactured by Fuji Kikai Co., Ltd. (cell shape: honeycomb, number of gravure rolls: 700 rolls/inch, rotation speed 140%/to line speed) A coating liquid was applied to the surface. The thickness of the resulting coating film was 1 μm. Next, the amorphous PET base material adjacent to the PVA layer was removed from the laminate a. The TAC film and laminate a were bonded together using a roll machine. At this time, the coating film and the PVA layer were brought into contact. The line speed of the roll machine was 25 m/min. Next, the obtained laminate was irradiated with active energy rays from the TAC film side. As the active energy ray, visible light emitted from the above-mentioned visible light irradiation device was used. By irradiating the laminate with active energy rays, the monomers in the coating were polymerized. The coating film was cured by polymerization of the monomer. Next, this laminate was dried with hot air at 70° C. for 3 minutes. As a result, a resin layer was formed.

Next, the surface of the transparent protective film containing the imidized MS resin was subjected to corona treatment. A 20 μm thick adhesive layer was attached to this surface. The adhesive layer was composed of an acrylic adhesive. As a result, a polarized light film comprising a TAC film (second transparent protective film), a resin layer, a polarizer, an adhesive layer, a transparent protective film containing imidized MS resin (first transparent protective film), and an adhesive layer in this order. Film B was obtained.

[Example 2-10 and Comparative Example 1]
Polarizing films A and Polarizing films of Example 2-10 and Comparative Example 1 were prepared in the same manner as in Example 1, except that the monomers contained in the coating liquid for forming the resin layer were changed to the monomers listed in Table 1. B was produced.

[Comparative example 2]
Polarizing films A and B of Comparative Example 2 were produced in the same manner as in Example 1, except that photocurable resin composition B was used as the coating liquid for forming the resin layer. Note that photocurable resin composition B contained 12 parts by weight of hydroxyethyl acrylamide (manufactured by KJ Chemicals, trade name: HEAA) and 20 parts by weight of 2-hydroxy-3-phenoxypropyl acrylate (manufactured by Toagosei Co., Ltd., trade name: HEAA). name: ARONIX M-5700), 12 parts by weight of hydroxypivalic acid neopentyl glycol acrylic acid adduct (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate HPP-A), 34 parts by weight of 1,9-nonanediol diacrylate (manufactured by Kyoeisha Kagaku Co., Ltd., trade name: Light Acrylate 1,9ND-A), 10 parts by weight of acrylic oligomer (manufactured by Toagosei Co., Ltd., trade name: ARUFON UP-1190), 5 parts by weight of diethyl acrylamide (manufactured by KJ Chemicals Co., Ltd.) , trade name: DEAA), 3 parts by weight of 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (manufactured by IGM Resins, trade name: OMNIRAD 907), and 3 parts by weight of , 4-diethylthioxanthone (manufactured by Nippon Kayaku Co., Ltd., trade name: KAYACURE DETX-S).

[Comparative example 3]
Polarizing films A and B of Comparative Example 3 were produced in the same manner as in Example 1, except that photocurable resin composition A was used as the coating liquid for forming the resin layer. Photocurable resin composition A contained 43 parts by weight of acroylmorpholine (manufactured by KJ Chemicals, trade name: ACMO), 29 parts by weight of 1,9-nonanediol diacrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light). Acrylate 1,9ND-A), 14 parts by weight of phenoxydiethylene glycol acrylate (manufactured by Kyoeisha Chemical Co., Ltd., trade name: Light Acrylate P2H-A), 10 parts by weight of acrylic oligomer (manufactured by Toagosei Co., Ltd., trade name: ARUFON UP-1190) ), 2 parts by weight of 2-methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one (manufactured by IGM Resins, trade name: OMNIRAD 907) and 2 parts by weight of 2,4-diethylthioxanthone. (manufactured by Nippon Kayaku Co., Ltd., trade name: KAYACURE DETX-S).

<Change in single transmittance ΔY1>
Regarding the polarizing films A of Examples and Comparative Examples, the change in single transmittance ΔY1 was measured by the following method. First, polarizing film A was bonded to alkali-free glass via an adhesive layer. The single transmittance Ts1 of the obtained laminate was measured. The single transmittance Ts1 was measured using a spectral transmittance measuring device with an integrating sphere (Dot-3c manufactured by Murakami Color Research Institute). Next, this laminate was placed in an atmosphere of 65° C. and 90% RH for 24 hours. After placing the laminate in this atmosphere, the single transmittance Ts2 was measured using the above-mentioned spectral transmittance measuring device. A change ΔY1 in the single transmittance was calculated by subtracting the single transmittance Ts1 from the single transmittance Ts2.

<Change in single transmittance ΔY2>
Regarding the polarizing films B of Examples and Comparative Examples, the change in single transmittance ΔY2 was measured by the following method. First, polarizing film B was bonded to alkali-free glass via an adhesive layer. The single transmittance Ts3 of the obtained laminate was measured. The single transmittance Ts3 was measured using a spectral transmittance measuring device with an integrating sphere (Dot-3c manufactured by Murakami Color Research Institute). Next, this laminate was placed in an atmosphere of 65° C. and 90% RH for 120 hours. After placing the laminate in this atmosphere, the single transmittance Ts4 was measured using the above-mentioned spectral transmittance measuring device. A change ΔY2 in the single transmittance was calculated by subtracting the single transmittance Ts3 from the single transmittance Ts4.

<Tensile storage modulus E1 and E2>
The tensile storage moduli E1 and E2 of the resin layers used in Examples and Comparative Examples were measured by the method described above. As the dynamic viscoelasticity measuring device, a dynamic viscoelasticity measuring device RSA-G2 manufactured by TA Instruments was used.

<Linear expansion coefficient α1 and α2>
The linear expansion coefficients α1 and α2 of the resin layers used in Examples and Comparative Examples were measured by the method described above. As the thermomechanical analyzer, a thermomechanical analyzer TMA 4000 SE manufactured by Netsch was used.

<Dipole moment D>
The dipole moment D was calculated by the method described above for the monomer contained in the coating liquid for forming the resin layer used in the Examples and Comparative Examples. Materials Studio (manufactured by BIOVIA, ver. 8.0.0.843) and WebMO (ver. 19.0.009e) were used to calculate the dipole moment D.

In addition, the abbreviations in Table 1 are as follows.
FA513AS: Dicyclopentanyl acrylate, manufactured by Hitachi Chemical Co., Ltd. TBCHA: 4-t-butylcyclohexyl acrylate, manufactured by KJ Chemicals Co., Ltd. LA: Lauryl acrylate, manufactured by Kyoeisha Chemical Co., Ltd. ACMO: Acryloylmorpholine, manufactured by KJ Chemicals Co., Ltd. DCP-A: Dimethylol-tricyclodecane diacrylate, manufactured by Kyoeisha Chemical Co., Ltd. TMP-A: Trimethylolpropane triacrylate, manufactured by Kyoeisha Chemical Co., Ltd. PE-4A: Pentaerythritol tetraacrylate, manufactured by Kyoeisha Chemical Co., Ltd. DPE-6A: Dipentaerythritol hexaacrylate, manufactured by Kyoeisha Chemical Co., Ltd. Manufactured by Kagakusha 1,9ND-A: 1,9-nonanediol diacrylate, manufactured by Kyoeisha Kagakusha

As can be seen from Table 1, in the polarizing film A of the example in which at least one of the requirements (i) to (v) is satisfied, the change in single transmittance ΔY1 is 5 or less, and the external iodine in a high temperature and humid environment is The permeation was sufficiently suppressed. Similarly, in the polarizing film B of Example, the change in single transmittance ΔY2 was 3 or less, and the transmission of iodine to the outside in a high temperature and humid environment was sufficiently suppressed. On the other hand, in the polarizing films A and B of comparative examples in which none of the requirements (i) to (v) are satisfied, the change in single transmittance is large compared to the example, and the transmission of iodine to the outside in a high temperature and humid environment is could not be suppressed sufficiently.

The polarizing film of the present invention can be suitably used, for example, in mobile displays such as mobile phones, smartphones, and notebook computers; in-vehicle displays such as panels for car navigation devices, cluster panels, and mirror displays.

1 Polarizer 2 Resin layer 3 Adhesive layer 4 First transparent protective film 5 Adhesive layer 6 Second transparent protective film 10, 11, 12, 13 Polarizing film 20 Image display panel 100 Image display device

Claims (14)

A polarizer containing iodine,
A resin layer containing a polymer,
The polymer includes a structural unit derived from a monofunctional (meth)acrylic acid ester and a structural unit derived from a polyfunctional monomer,
A polarizing film that satisfies all of the following requirements (i) to (v) .
(i) The tensile storage modulus E1 of the resin layer at 65° C. in water is 1×10 ⁸ Pa or more.
(ii) The resin layer has a tensile storage modulus E2 of 1×10 ⁸ Pa or more at 85° C. in water .
(iii) The resin layer has a linear expansion coefficient α1 of 400×10 ^-6 /K or less when the resin layer is heated from 25° C. to 65° C. and the measurement atmosphere is humidified from 10% RH to 90% RH. be.
(iv) The resin layer has a linear expansion coefficient α2 of 300×10 ^-6 /K or less when the resin layer is heated from 25° C. to 85° C. and the measurement atmosphere is humidified from 10% RH to 85% RH. be.
(v) The dipole moment D of the monomer for forming the polymer is 2 Debye or less. A polarizer containing iodine,
A resin layer containing a polymer,
The polymer contains a structural unit derived from a monofunctional (meth)acrylic ester,
The content of structural units derived from a monomer having a polar group in the polymer is 20% by weight or less,
A polarizing film that satisfies all of the following requirements (i) to (v) .
(i) The tensile storage modulus E1 of the resin layer at 65° C. in water is 1×10 ⁸ Pa or more.
(ii) The resin layer has a tensile storage modulus E2 of 1×10 ⁸ Pa or more at 85° C. in water .
(iii) The resin layer has a linear expansion coefficient α1 of 400×10 ^-6 /K or less when the resin layer is heated from 25° C. to 65° C. and the measurement atmosphere is humidified from 10% RH to 90% RH. be.
(iv) The resin layer has a linear expansion coefficient α2 of 300×10 ^-6 /K or less when the resin layer is heated from 25° C. to 85° C. and the measurement atmosphere is humidified from 10% RH to 85% RH. be.
(v) The dipole moment D of the monomer for forming the polymer is 2 Debye or less. The polarizing film according to claim 1 or 2 , wherein the linear expansion coefficient α1 of the resin layer is 180×10 ⁻⁶ /K or less. The polarizing film according to any one of claims 1 to 3 , wherein the content of structural units derived from ( meth)acrylic ester in the polymer is higher than 70% by weight. The polarizing film according to claim 2, wherein the polymer contains a structural unit derived from a polyfunctional monomer. The polarizing film according to claim 1 or 5 , wherein the content of the structural unit derived from the polyfunctional monomer in the polymer is 20% by weight or more. The polarizing film according to claim 1, wherein the content of structural units derived from a monomer having a polar group in the polymer is 20% by weight or less. The polarizing film according to any one of claims 1 to 7 , wherein the resin layer is located closer to the viewing side than the polarizer. The polarizing film according to any one of claims 1 to 8 , wherein the resin layer is in direct contact with the polarizer. comprising two of the resin layers,
The polarizing film according to any one of claims 1 to 7 , wherein the polarizer is located between the two resin layers. further comprising an adhesive layer and a first transparent protective film,
The polarizing film according to any one of claims 1 to 10 , wherein the polarizer, the adhesive layer, and the first transparent protective film are arranged in this order in the lamination direction. further comprising a second transparent protective film,
The polarizing film according to claim 11 , wherein the polarizer is located between the first transparent protective film and the second transparent protective film. Further equipped with an adhesive layer,
The polarizing film according to any one of claims 1 to 12 , wherein the polarizer is located closer to the viewing side than the adhesive layer. The polarizing film according to any one of claims 1 to 13 ,
an image display panel;
An image display device equipped with

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