KR20210122699A - Polarizing plate and image display device using the polarizing plate - Google Patents

Abstract

Provided is a polarizing plate in which the decrease in transmissivity is suppressed even when used for an image display device with an interlayer charging configuration, for example, when exposed to a high-temperature environment with the temperature of 105℃. The polarizing plate comprises a polarizing element formed by adsorbing and orienting bichromatic pigments in a polyvinyl alcohol-based resin layer. A polyvinyl alcohol-based resin used to form the polyvinyl alcohol-based resin layer has a boron adsorption rate of 5.70 wt% or more. Moisture content of the polarizing element is equal to or higher than equilibrium moisture content with the temperature of 20℃ and relative humidity of 30% and equal to or lower than equilibrium moisture content with the temperature of 20℃ and relative humidity of 50%.

Description

A polarizing plate and an image display device using the polarizing plate

The present invention relates to a polarizing plate. Further, the present invention relates to an image display device in which one surface of the polarizing plate is bonded to an image display cell and the other surface is bonded to a transparent member such as a touch panel or a front plate.

BACKGROUND ART Liquid crystal display devices (LCDs) are widely used not only for liquid crystal televisions, but also for mobile devices such as personal computers and cell phones, and in-vehicle applications such as vehicle navigation systems. Usually, a liquid crystal display device has the liquid crystal panel member which bonded the polarizing plate together with the adhesive on both sides of a liquid crystal cell, and display is performed by controlling the light from a backlight member with the liquid crystal panel member. Moreover, organic electroluminescent display apparatuses are also widely used for in-vehicle applications, such as mobiles, such as a television and a mobile phone, and a vehicle navigation, similarly to a liquid crystal display device in recent years. In an organic EL display device, in order to suppress external light from being reflected by a metal electrode (cathode) and visually recognized like a mirror surface, a circularly polarizing plate (laminated including a polarizing element and a λ/4 plate) is placed on the surface of the image display panel on the viewing side. sieve) may be placed.

As mentioned above, the opportunity for a polarizing plate to be mounted in a vehicle as a member of a liquid crystal display device or organic electroluminescent display device is increasing. Since the polarizing plate used in the vehicle-mounted image display device is often exposed to a high-temperature environment compared to other mobile applications such as televisions and mobile phones, it is expected that the characteristic change at a higher temperature is small (high-temperature durability). is required

On the other hand, for the purpose of preventing damage to the image display panel due to impact from the outer surface, etc., a front plate such as a transparent resin plate or a glass plate (also called a “window layer”) is installed on the viewing side further than the polarizing plate of the image display panel. composition is increasing. Moreover, in the display apparatus provided with a touch panel, the structure which provided the touch panel on the visual recognition side further than the polarizing plate of an image display panel, and provided the front transparent plate on the visual recognition side further than the touch panel is widely employ|adopted.

In such a configuration, when an air layer exists between the image display panel and a transparent member such as a front transparent plate or a touch panel, glare of external light due to reflection of light at the air layer interface occurs, and the visibility of the screen tends to decrease. have. Therefore, the space between the polarizing plate and the transparent member disposed on the surface of the image display panel on the viewer side is usually filled with a solid layer (hereinafter, sometimes referred to as “interlayer filler”) as a layer other than the air layer ( Hereinafter, it may be referred to as an "interlayer filling structure"), preferably a structure filled with a material having a refractive index close to those of these materials is being adopted. As an interlayer filler, an adhesive and a UV curable adhesive are used for the purpose of suppressing the fall of visibility by reflection at an interface, and adhesive fixing between each member (for example, refer patent document 1).

Adoption of the above-mentioned interlayer charging structure in mobile applications, such as a cellular phone, which is used outdoors in many cases, is expanding. In addition, in recent years, the demand for visibility has increased, and in in-vehicle applications such as vehicle navigation devices, a front transparent plate is arranged on the surface of an image display panel and an interlayer filling configuration is adopted in which the space between the panel and the front transparent plate is filled with an adhesive layer or the like. This is being reviewed.

However, it has been reported that, when an image display device having such a configuration is left to stand for 200 hours under an environment of a temperature of 95°C, a significant decrease in transmittance is seen in the central portion of the plane of the polarizing plate. On the other hand, it is also reported that a polarizing plate alone does not show a significant decrease in transmittance even when left to stand for 1000 hours in an environment of a temperature of 95°C. From these results, the significant decrease in the transmittance of the polarizing plate under a high-temperature environment is an interlayer filling configuration in which one side of the polarizing plate is bonded to the image display cell and the other side is bonded to a transparent member such as a touch panel or front transparent plate. It is also reported that it is a problem peculiar to the case where the image display apparatus employ|adopted is exposed to a high-temperature environment (patent document 2).

In Patent Document 2, as a solution to the problem, a method of suppressing a decrease in transmittance by setting the amount of moisture per unit area of the polarizing plate to a predetermined amount or less and the saturated absorption amount of the transparent protective film adjacent to the polarizing element to not more than a predetermined amount is proposed. have.

[Patent Document 1] Japanese Patent Laid-Open No. 11-174417 [Patent Document 2] Japanese Patent Laid-Open No. 2014-102353

However, when the temperature of the test environment was raised to 105° C. and exposed in this high-temperature environment for a certain period of time, the transmittance fall was not sufficiently suppressed in some cases in the conventional polarizing plate. An object of the present invention is to provide a polarizing plate excellent in the effect of suppressing a decrease in transmittance even when used in an image display device having an interlayer filling configuration, for example, even when exposed to a high temperature environment of 105° C., and an image display device using the polarizing plate. do.

This invention provides the following polarizing plate, an image display apparatus, and the manufacturing method of a polarizing plate.

[1] A polarizing plate comprising a polarizing element formed by adsorbing and aligning a dichroic dye to a polyvinyl alcohol-based resin layer and a transparent protective film,

The polyvinyl alcohol-based resin used to form the polyvinyl alcohol-based resin layer has a boron adsorption rate of 5.70 mass% or more,

A polarizing plate in which the moisture content of the polarizing element is equal to or greater than an equilibrium moisture content at a temperature of 20°C and a relative humidity of 30% and equal to or less than an equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%.

[2] A polarizing plate comprising a polarizing element formed by adsorbing and aligning a dichroic dye to a polyvinyl alcohol-based resin layer and a transparent protective film,

The polyvinyl alcohol-based resin used to form the polyvinyl alcohol-based resin layer has a boron adsorption rate of 5.70 mass% or more,

A polarizing plate in which the moisture content of the polarizing plate is equal to or greater than an equilibrium moisture content of 30% relative humidity at a temperature of 20°C and less than or equal to an equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%.

[3] The polarizing plate according to [1] or [2], wherein the polarizing element has a boron content of 4.0 mass% or more and 8.0 mass% or less.

[4] further comprising an adhesive layer for bonding the polarizing element and the transparent protective film;

The polarizing plate according to any one of [1] to [3], wherein the adhesive layer is a coating layer of a water-based adhesive.

[5] The polarizing plate according to [4], wherein the water-based adhesive has a methanol concentration of 10% by mass or more and 70% by mass or less.

[6] The polarizing plate according to [4] or [5], wherein the water-based adhesive contains a polyvinyl alcohol-based resin.

[7] The polarizing plate according to any one of [4] to [6], wherein the adhesive layer has a thickness of 0.01 µm or more and 7 µm or less.

[8] the transparent protective film is a retardation film including a first optical compensation layer and a second optical compensation layer sequentially from the polarizing element side,

an absorption axis of the polarizing element and a slow axis of the first optical compensation layer are substantially orthogonal to each other;

The slow axis of the first optical compensation layer and the slow axis of the second optical compensation layer are approximately parallel;

The polarizing plate according to any one of [1] to [7], wherein the first optical compensation layer and the second optical compensation layer satisfy the following formulas (1) to (4).

80 nm≤Re ₁ (590)≤120 nm (1)

20 nm<Re ₁ (590)≤60 nm (2)

1<Nz ₁ <2 (3)

-4<Nz ₂ <-1 (4)

[9] The polarizing plate is used in an image display device,

The polarizing plate according to any one of [1] to [8], wherein a solid layer is formed in contact with both surfaces of the polarizing plate in the image display device.

[10] any one of [1] to [9], wherein an image display cell, a first pressure-sensitive adhesive layer laminated on the surface of the image display cell on the viewing side, and the first pressure-sensitive adhesive layer are laminated on the surface on the viewing side of the image display cell The image display apparatus which has the polarizing plate as described in.

[11] The image display device according to [10], further comprising a second pressure-sensitive adhesive layer laminated on the surface of the polarizing plate on the viewing side, and a transparent member laminated on the surface on the viewing side of the second pressure-sensitive adhesive layer.

[12] The image display device according to [11], wherein the transparent member is a glass plate or a transparent resin plate.

[13] The image display device according to [11], wherein the transparent member is a touch panel.

[14] A method for producing a polarizing plate according to [1], comprising:

A method for manufacturing a polarizing plate having a polarizing element and a transparent protective film,

A moisture content adjustment step of adjusting the moisture content of the polarizing element to be equal to or higher than the equilibrium moisture content of 30% relative humidity at a temperature of 20°C and less than or equal to the equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%;

Lamination process of laminating the polarizing element and the transparent protective film

A method of manufacturing a polarizing plate having

[15] A method for producing a polarizing plate according to [2], comprising:

A method for manufacturing a polarizing plate having a polarizing element and a transparent protective film,

A moisture content adjustment step of adjusting the moisture content of the polarizing plate to be equal to or greater than the equilibrium moisture content of 30% relative humidity at a temperature of 20° C. and less than or equal to the equilibrium moisture content at a temperature of 20° C. of 50% of the relative humidity;

Lamination process of laminating the polarizing element and the transparent protective film

A method of manufacturing a polarizing plate having

According to the present invention, even when used in an image display device having an interlayer filling configuration, a decrease in transmittance when exposed to a high temperature environment of, for example, a temperature of 105° C. is suppressed, and it becomes possible to provide a polarizing plate excellent in high temperature durability, further By using the polarizing plate of this invention, it becomes possible to provide the image display apparatus by which the fall of the transmittance|permeability in a high-temperature environment was suppressed.

EMBODIMENT OF THE INVENTION Hereinafter, although embodiment of this invention is described, this invention is not limited to the following embodiment.

[Polarizer]

A polarizing plate according to an embodiment of the present invention has a polarizing element formed by adsorbing and orienting a dichroic dye to a layer containing a polyvinyl alcohol-based resin, and a transparent protective film. The polarizing element is formed using a polyvinyl alcohol-based resin having a boron adsorption rate of 5.70 mass% or more. The polarizing plate which concerns on this embodiment has at least one characteristic of following (a) and (b).

(a) The moisture content of the polarizing element is equal to or greater than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 30% and equal to or less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%.

(b) The moisture content of the polarizing plate is equal to or greater than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 30% and equal to or less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%.

The polarizing plate of the present embodiment has at least one of the characteristics of (a) and (b) described above, and furthermore, the boron adsorption rate of the polyvinyl alcohol-based resin used for the polarizing element is within the above-described range. As a component of an image display device of

<Polarizing element>

Polarized light well known as a polarizing element formed by adsorbing and aligning a dichroic dye to a layer containing a polyvinyl alcohol (hereinafter, also referred to as "PVA")-based resin of the present invention (also referred to as a "PVA-based resin layer" in this specification) small can be used. As such a polarizing element, a PVA-based resin film is used, and the PVA-based resin film is dyed with a dichroic dye and formed by uniaxial stretching, and a laminated film obtained by applying a coating liquid containing a PVA-based resin on a base film. What was formed by dyeing the PVA-type resin layer which is an application layer of this laminated|multilayer film with a dichroic dye using and uniaxially stretching a laminated|multilayer film is mentioned.

A polarizing element is formed from PVA-type resin obtained by saponifying polyvinyl acetate-type resin. As polyvinyl acetate-type resin, the copolymer of vinyl acetate and other monomer copolymerizable to this other than polyvinyl acetate which is a homopolymer of vinyl acetate is mentioned. Examples of other copolymerizable monomers include unsaturated carboxylic acids and olefins such as ethylene, vinyl ethers, and unsaturated sulfonic acids.

In the present invention, the PVA-based resin layer is formed of a PVA-based resin having a boron adsorption rate of 5.70% by mass or more. That is, the boron adsorption rate of the PVA-type resin in the raw material stage before dyeing or extending|stretching is 5.70 mass % or more. By using such a PVA-type resin, the transmittance|permeability becomes difficult to fall even when it exposes to the high temperature environment of a temperature of 105 degreeC, for example. A polarizing element is produced using PVA-type resin which has a boron adsorption rate more preferably 5.72 mass % or more, More preferably, is 5.75 mass %, and most preferably 5.80 mass % or more. Moreover, it is preferable that the boron adsorption rate of PVA-type resin is 10 mass % or less. By producing a polarizing element using such PVA-based resin, the processing time by boric acid treatment can also be shortened without making the boric acid concentration in the boric acid treatment tank high, and the desired polarizing element can be easily obtained, and productivity of the polarizing element can also be increased. When the boron adsorption rate of PVA-type resin shall be 10 mass % or less, an appropriate amount of boron will be taken in into the PVA-type resin layer, and it will be easy to make small the shrinkage force of a polarizing element. As a result, when it assembles in an image display apparatus, it becomes difficult to produce problems, such as peeling arises between other members, such as a front plate, and a polarizing plate. In addition, when the boron adsorption rate of the PVA-based resin is less than 5.70%, the transmittance tends to decrease even when exposed to a high temperature environment of, for example, a temperature of 105° C., and furthermore, as described above, productivity may decrease. The boron adsorption rate of the PVA-based resin can be measured by the method described in Examples to be described later.

The boron adsorption rate of PVA-type resin is the characteristic of PVA-type resin which reflected the space|interval and crystal structure of molecular chains in PVA-type resin. It is considered that the PVA-based resin having a boron adsorption rate of 5.70 mass% or more has a wider spacing between molecular chains and fewer crystals of the PVA-based resin as compared with a PVA-based resin having a boron adsorption rate of less than 5.70 mass%. Therefore, it is estimated that boron becomes easy to enter into the PVA-type resin layer, and polyenization becomes easy to prevent in a high-temperature environment.

The boron adsorption rate of the PVA-based resin can be adjusted, for example, by pre-treating the PVA-based resin, such as hydrothermal treatment, acidic solution treatment, ultrasonic irradiation treatment, or radiation treatment, in a step before manufacturing the polarizing element. By these treatments, the distance between molecular chains in the PVA-based resin can be widened or the crystal structure can be destroyed. Examples of the hydrothermal treatment include a treatment in which water is immersed in pure water at 30°C to 100°C for 1 second to 90 seconds and dried. Examples of the acidic solution treatment include a treatment in which a 10% to 20% concentration boric acid aqueous solution is immersed for 1 second to 90 seconds and dried. Examples of the ultrasonic treatment include a process in which ultrasonic waves having a frequency of 20 kc to 29 kc are irradiated with an output of 200 W to 500 W for 30 seconds to 10 minutes. The ultrasonic treatment can be performed in a solvent such as water.

The degree of saponification of the PVA-based resin is preferably about 85 mol% or more, more preferably about 90 mol% or more, and still more preferably about 99 mol% to 100 mol%. The polymerization degree of PVA-type resin is 1000-10000, Preferably it is 1500-5000. The PVA-based resin may be modified, for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral or the like modified with aldehydes.

5-50 micrometers is preferable, as for the thickness of the polarizing element of this embodiment, 8-28 micrometers is more preferable, 12-22 micrometers is still more preferable, 12-15 micrometers is the most preferable. When the thickness of the polarizing element is 50 µm or less, the influence of polyeneization of the PVA-based resin on the deterioration of optical properties under a high-temperature environment can be suppressed, and when the thickness of the polarizing element is 5 µm or more, desired optical properties are achieved This configuration makes it easy to do.

The polarizing element preferably has a boron content of 4.0 mass% or more and 8.0 mass% or less, more preferably 4.2 mass% or more and 7.0 mass% or less, and still more preferably 4.4 mass% or more and 6.0 mass% or less. When the boron content of the polarizing element exceeds 8.0% by mass, the contracting force of the polarizing element increases, causing problems such as separation from other members such as a front plate to be bonded when assembled into an image display device. There are cases. Moreover, when the content rate of boron is less than 2.4 mass %, a desired optical characteristic may not be achieved. In addition, the content rate of boron in a polarizing element can be calculated as a mass fraction (mass %) of boron with respect to the mass of a polarizing element by, for example, high frequency inductively coupled plasma (ICP) emission spectroscopy. It is thought that boron exists in the state in which boric acid or it formed the structural component of polyvinyl alcohol-type resin and crosslinked structure in a polarizing element, However, The content rate of boron here is a value as a boron atom (B).

Since the polarizing element has a boron content of 4.0 mass% or more and 8.0 mass% or less, a decrease in transmittance is suppressed even when exposed to a high-temperature environment as a component of an image display device having an interlayer charging configuration. When the content rate of boron is 4.0 mass % or more and 8.0 mass % or less in a polarizing element, polyenization becomes difficult to occur also under a high-temperature environment, and this is guessed because the transmittance|permeability fall is suppressed.

The content rate of potassium in the polarizing element is preferably 0.28 mass% or more, more preferably 0.32 mass% or more, and 0.34 mass% or more from the viewpoint of suppressing a decrease in the optical properties of the polarizing element in a high-temperature environment. More preferably, it is preferably 0.60 mass% or less, more preferably 0.55 mass% or less, and still more preferably 0.50 mass% or less from the viewpoint of suppressing color change in a high-temperature environment.

Although the detailed mechanism is unclear, since the content of boron is higher and the content of potassium is lower than that of the conventional polarizing element, the hydroxyl group of polyvinyl alcohol in the polarizing element is protected (stabilized) by boric acid crosslinking. Since iodine ions serving as counter ions in the device are stabilized, it is presumed that polyenization can be suppressed.

The transmittance of the polarizing element for correction of visibility is preferably 38.8% to 44.8%, more preferably 40.4% to 43.2%, and still more preferably 40.7% to 43.0%. When the transmittance of the visibility correction monolith exceeds 44.8%, deterioration of optical properties such as redness in a high-temperature environment may increase. The deterioration of the optical characteristic may become large.

Visibility correction The monolithic transmittance|permeability can be calculated|required by measuring the Y value which performed the visibility correction|amendment with the 2 degree field of view (C light source) prescribed|regulated to JIS Z8701-1982. Visibility correction The monolithic transmittance can be easily measured with, for example, a spectrophotometer (model number: V7100) manufactured by Nippon Bunko Co., Ltd. or the like.

Although the manufacturing method of a polarizing element is not specifically limited, The method of sending out the polyvinyl alcohol-type resin film previously wound in roll shape, and performing extending|stretching, dyeing, crosslinking, etc. to produce (hereinafter referred to as "manufacturing method 1") or poly A method including a step of stretching a laminate obtained by applying a coating liquid containing a vinyl alcohol-based resin on a base film to form a polyvinyl alcohol-based resin layer as an application layer (hereinafter referred to as “manufacturing method 2”) This is typical.

Manufacturing method 1 is a step of uniaxially stretching a polyvinyl alcohol-based resin film, a step of adsorbing the dichroic dye by dyeing the polyvinyl alcohol-based resin film with a dichroic dye such as iodine, polyvinyl to which the dichroic dye is adsorbed It can manufacture through the process of processing an alcohol-type resin film with boric-acid aqueous solution, and the process of washing with water after the process with boric-acid aqueous solution.

The content rate of boron and the content rate of potassium contained in a polarizing element are boric acid, borate, borax, etc. contained in any one of each treatment bath in a swelling process, a dyeing process, a bridge|crosslinking process, an extending process, and a water washing process. It can be controlled by the concentration of a boron component donor material such as a boron compound of In particular, by changing the treatment conditions such as the concentration of the boron component donor material in the crosslinking step and the stretching step, it is easy to adjust the boron content to a desired range. In addition, in the water washing step, after considering treatment conditions such as the amount of the boron component donor material or the potassium component donor material used in the dyeing step, crosslinking step, or stretching step, etc., components such as boron and potassium are eluted from the polyvinyl alcohol-based resin film. or it can be made to adsorb|suck to a polyvinyl alcohol-type resin film, it is easy to adjust the content rate of boron and content rate of potassium to desired ranges.

The swelling step is a treatment step in which the polyvinyl alcohol-based resin film is immersed in a swelling bath, and contaminants and blocking agents on the surface of the polyvinyl alcohol-based resin film can be removed, and further, the polyvinyl alcohol-based resin film It is possible to suppress the dyeing unevenness by swelling the. As the swelling bath, a medium containing water as a main component, such as water, distilled water, or pure water, is usually used. The swelling bath may be suitably added with surfactant, alcohol, etc. according to a conventional method. In addition, from the viewpoint of controlling the potassium content of the polarizing element, potassium iodide may be used in the swelling bath. In this case, the concentration of potassium iodide in the swelling bath is preferably 1.5% by weight or less, and more preferably 1.0% by weight or less. Preferably, it is more preferably 0.5 wt% or less.

It is preferable that the temperature of a swelling bath is about 10-60 degreeC, It is more preferable that it is about 15-45 degreeC, It is more preferable that it is about 18-30 degreeC. In addition, the immersion time in the swelling bath cannot be determined uniformly because the degree of swelling of the polyvinyl alcohol-based resin film is affected by the temperature of the swelling bath, but it is preferably about 5 to 300 seconds, and about 10 to 200 seconds. It is more preferable, and it is still more preferable that it is about 20 to 100 second. A swelling process may be implemented only once, and may be implemented in multiple times as needed.

The dyeing process is a treatment process in which a polyvinyl alcohol-based resin film is immersed in a dyeing bath (iodine solution), and a dichroic substance such as iodine or a dichroic dye is adsorbed and oriented to the polyvinyl alcohol-based resin film. can The iodine solution is usually preferably an iodine aqueous solution, and contains iodine and iodide as a dissolution aid. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, titanium iodide, and the like. Among these, potassium iodide is suitable from a viewpoint of controlling the potassium content in a polarizing element.

It is preferable that it is about 0.01 to 1 weight%, and, as for the density|concentration of iodine in a dyeing bath, it is more preferable that it is about 0.02 to 0.5 weight%. The concentration of iodide in the dyeing bath is preferably about 0.01 to 10% by weight, more preferably about 0.05 to 5% by weight, and still more preferably about 0.1 to 3% by weight.

It is preferable that the temperature of a dyeing bath is about 10-50 degreeC, It is more preferable that it is about 15-45 degreeC, It is more preferable that it is about 18-30 degreeC. In addition, the immersion time in the dyeing bath cannot be determined uniformly because the degree of dyeing of the polyvinyl alcohol-based resin film is affected by the dyeing bath temperature, but it is preferably about 10 to 300 seconds, and about 20 to 240 seconds. more preferably. The dyeing process may be performed only once, and may be performed multiple times as needed.

The crosslinking step is a treatment step in which the polyvinyl alcohol-based resin film dyed in the dyeing step is immersed in a treatment bath (crosslinking bath) containing a boron compound, the polyvinyl alcohol-based resin film is crosslinked by the boron compound, and iodine molecules Alternatively, dye molecules may be adsorbed to the cross-linked structure. As a boron compound, boric acid, a borate, borax, etc. are mentioned, for example. The crosslinking bath is generally an aqueous solution, but may be, for example, a mixed solution of water and an organic solvent miscible with water. Moreover, it is preferable that a crosslinking bath contains potassium iodide from a viewpoint of controlling the potassium content in a polarizing element.

The concentration of the boron compound in the crosslinking bath is preferably about 1 to 15% by weight, more preferably about 1.5 to 10% by weight, and more preferably about 2 to 5% by weight. Further, when potassium iodide is used in the crosslinking bath, the concentration of potassium iodide in the crosslinking bath is preferably about 1 to 15% by weight, more preferably about 1.5 to 10% by weight, and about 2 to 5% by weight. It is more preferable that

It is preferable that it is about 20-70 degreeC, and, as for the temperature of a crosslinking bath, it is more preferable that it is about 30-60 degreeC. The immersion time in the crosslinking bath cannot be determined uniformly because the degree of crosslinking of the polyvinyl alcohol-based resin film is affected by the crosslinking bath temperature, but it is preferably about 5 to 300 seconds, and about 10 to 200 seconds. more preferably. A crosslinking process may be performed only once, and may be performed multiple times as needed.

The stretching step is a treatment step of stretching the polyvinyl alcohol-based resin film in at least one direction at a predetermined magnification. Generally, a polyvinyl alcohol-type resin film is uniaxially stretched in a conveyance direction (longitudinal direction). The stretching method is not particularly limited, and either a wet stretching method or a dry stretching method can be employed. An extending process may be performed only once, and may be performed multiple times as needed. An extending process may be implemented at any stage in manufacture of a polarizing element.

As the treatment bath (stretching bath) in the wet stretching method, a solvent such as water or a mixed solution of water and an organic solvent miscible with water can be used. It is preferable that a stretching bath contains potassium iodide from a viewpoint of controlling the potassium content rate in a polarizing element. When potassium iodide is used in the stretching bath, the concentration of potassium iodide in the stretching bath is preferably about 1 to 15% by weight, more preferably about 2 to 10% by weight, and about 3 to 6% by weight. more preferably. In addition, the treatment bath (stretching bath) may contain a boron compound from the viewpoint of suppressing breakage of the film being stretched. In this case, the concentration of the boron compound in the stretching bath is about 1 to 15% by weight. It is more preferable that it is about 1.5 to 10 weight%, and it is more preferable that it is about 2 to 5 weight%.

It is preferable that the temperature of a stretching bath is about 25-80 degreeC, It is more preferable that it is about 40-75 degreeC, It is more preferable that it is about 50-70 degreeC. The immersion time in the stretching bath cannot be determined uniformly because the stretching degree of the polyvinyl alcohol-based resin film is affected by the stretching bath temperature, but it is preferably about 10 to 800 seconds, and about 30 to 500 seconds. more preferably. In addition, you may perform the extending|stretching process in a wet extending|stretching method together with any one or more treatment processes of a swelling process, a dyeing|staining process, a bridge|crosslinking process, and a washing|cleaning process.

Examples of the dry stretching method include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. In addition, you may implement the dry extending|stretching method together with a drying process.

Although the total draw ratio (cumulative draw ratio) applied to a polyvinyl alcohol-type resin film can be set suitably according to the objective, It is preferable that it is about 2 to 7 times, It is more preferable that it is about 3 to 6.8 times, It is 3.5- It is more preferable that it is about 6.5 times.

The washing step is a treatment step in which the polyvinyl alcohol-based resin film is immersed in a washing bath, and foreign substances remaining on the surface of the polyvinyl alcohol-based resin film or the like can be removed. As the washing bath, a medium containing water as a main component, such as water, distilled water, or pure water, is usually used. In addition, from the viewpoint of controlling the potassium content in the polarizing element, it is preferable to use potassium iodide in the washing bath, and in this case, the concentration of potassium iodide in the washing bath is preferably about 1 to 10% by weight, and 1.5 to It is more preferable that it is about 4 weight%, and it is still more preferable that it is about 1.8 to 3.8 weight%.

It is preferable that the temperature of a washing bath is about 5-50 degreeC, It is more preferable that it is about 10-40 degreeC, It is more preferable that it is about 15-30 degreeC. The immersion time in the washing bath cannot be determined uniformly because the degree of washing of the polyvinyl alcohol-based resin film is affected by the washing bath temperature, but it is preferably about 1 to 100 seconds, and about 2 to 50 seconds. It is more preferable, and it is still more preferable that it is about 3 to 20 second. A washing process may be performed only once, and may be performed multiple times as needed.

A drying process is a process of drying the polyvinyl alcohol-type resin film wash|cleaned by the washing|cleaning process, and obtaining a polarizing element. Drying is carried out by any suitable method, such as air drying, air drying, or heat drying.

Manufacturing method 2 is a process of applying the coating liquid containing the polyvinyl alcohol-based resin on a base film, a process of uniaxially stretching the obtained laminated film, and a dichroic dye for the polyvinyl alcohol-based resin layer of the uniaxially stretched laminated film. It can be produced through a step of adsorbing the dichroic dye to obtain a polarizing element by dyeing it with, a step of treating the film to which the dichroic dye has been adsorbed with an aqueous boric acid solution, and a step of washing with water after treatment with an aqueous boric acid solution. You may use the base film used in order to form a polarizing element as a protective layer of a polarizing element. You may peel and remove a base film from a polarizing element as needed.

<Transparent protective film>

The transparent protective film (henceforth simply called a "protective film") used in this embodiment is bonded to at least one surface of a polarizing element via an adhesive bond layer. Although this transparent protective film is bonded to one side or both surfaces of a polarizing element, bonding to both surfaces is more preferable.

The protective film may have another optical function at the same time, and may be formed in the laminated structure in which several layers were laminated|stacked. Although it is preferable that the film thickness of a protective film is thin from a viewpoint of an optical characteristic, when it is too thin, intensity|strength will fall and it will become inferior to workability. A suitable film thickness is 5 to 100 m, preferably 10 to 80 m, more preferably 15 to 70 m.

The protective film is a cellulose acylate-based resin film, a polycarbonate-based resin film, a cycloolefin-based resin such as norbornene, a (meth)acrylic polymer film, or a polyester-based resin film such as polyethylene terephthalate. Film can be used. In the case of a configuration having protective films on both surfaces of the polarizing element, at least one protective film is preferably either a cellulose acylate-based film or a (meth)acrylic-based polymer film, and among these, a cellulose acylate film is preferable. This is because, since these films have a relatively high moisture permeability, it is easy to dry a water-based adhesive such as a PVA adhesive.

As at least one protective film, the retardation function may be provided for the objective, such as viewing angle compensation. In this case, the film itself may have a retardation function, may have a retardation layer separately, and a combination of both may be sufficient.

In addition, although the configuration in which the film having the retardation function is directly bonded to the polarizing element through an adhesive has been described, it does not matter if the film having the retardation function is bonded by an adhesive or an adhesive through a separate protective film bonded to the polarizing element none.

For example, as a viewing angle compensation film used for optical compensation of a liquid crystal cell (hereinafter referred to as an IPS mode liquid crystal cell) having a liquid crystal layer comprising liquid crystal molecules oriented in a homogeneous arrangement in the absence of an electric field, the polarizing element It may be a retardation film consisting of a first optical compensation layer and a second optical compensation layer sequentially from the side. At this time, the surface of the second optical compensation layer is bonded to the liquid crystal cell using an adhesive or the like. The absorption axis of the polarizing element and the slow axis of the first optical compensation layer are substantially orthogonal to each other. The slow axis of the first optical compensation layer and the slow axis of the second optical compensation layer are approximately parallel. The first optical compensation layer and the second optical compensation layer may satisfy the following formulas (1) to (4).

80 nm≤Re ₁ (590)≤120 nm (1)

20 nm<Re ₂ (590)≤60 nm (2)

1<Nz ₁ <2 (3)

-4<Nz ₂ <-1 (4)

Here, each of the first optical compensation layer and the second optical compensation layer, nx ₁ , nx ₂ , the refractive index in the in-plane slow axis direction, ny ₁ , ny ₂ , and the refractive index in the thickness direction are nz _{When 1} , nz ₂ , Re ₁ (λ)=(nx ₁ -ny ₁ )×d ₁ , Re ₂ (λ)=(nx ₂ -ny ₂ )×d ₂ , Nz ₁ =(nx ₁ -nz ₁ )/(nx ₁ -ny ₁ ), Nz ₂ =(nx ₂ -nz ₂ )/(nx ₂ -ny ₂ ), and d ₁ , d ₂ are the first optical compensation layer and the second optical compensation layer, respectively. It represents the thickness, and λ represents the measurement wavelength.

In addition, "approximately parallel" includes not only perfectly parallel ones but also substantially parallel ones, and the angle is generally within ±2°, preferably within ±1°, more preferably within ±0.5°. am. In addition, "approximately orthogonal" includes not only perfectly orthogonal, but also substantially orthogonal, and the angle is generally in the range of 90±2°, preferably 90±1°, more preferably 90± It is in the range of 0.5.

(first optical compensation layer)

The first optical compensation layer _{satisfies Nz 1} >1 as described above. Such a retardation film may be called a "negative biaxial plate" or a "negative biaxial plate" in some cases.

The first optical compensation layer preferably satisfies the following formulas (1) and (3).

80 nm≤Re ₁ (590)≤120 nm (1)

1<Nz ₁ <2 (3)

_{The front retardation Re 1} (590) of the first optical compensation layer is more preferably 81 to 119 nm, still more preferably 85 to 115 nm, particularly preferably 90 to 110 nm.

Moreover, as for _{the value of Nz<1} >, it is more preferable that it is 1.15-1.6, It is still more preferable that it is 1.2-1.55, It is especially preferable that it is 1.25-1.5.

Furthermore, the first optical compensation layer preferably satisfies the following formula (5).

60 nm≤Rth ₁ (590)≤100 nm (5)

Here, Rth ₁ (590) = Re ₁ (590) x (Nz ₁ -0.5), indicating retardation in the thickness direction.

_{The retardation Rth 1} (590) in the thickness direction of the first optical compensation layer is more preferably 61 to 99 nm, still more preferably 65 to 95 nm, particularly preferably 70 to 90 nm.

The material and manufacturing method of the first optical compensation layer are not particularly limited as long as the above-described optical properties are satisfied. The first optical compensation layer may be a single retardation film or a laminate of two or more retardation films. Preferably, the first optical compensation layer is a single retardation film. It is because a liquid crystal panel can be made thin while reducing the shift|offset|difference and nonuniformity of the retardation value by the shrinkage stress of a polarizing element or the heat|fever of a light source. When the first optical compensation layer is a laminate, an adhesive layer or an adhesive layer for bonding two or more retardation films may be included. When the laminate includes two or more retardation films, these retardation films may be the same or different.

The optical characteristics of the retardation film used for the first optical compensation layer may be appropriately selected according to the number of retardation films used. For example, when the first optical compensation layer is constituted by the retardation film alone, the front retardation and the thickness direction retardation of the retardation film are respectively the front retardation Re ₁ (590) and the thickness direction retardation of the first optical compensation layer. Rth ₁ (590) is preferred. Accordingly, it is preferable that the retardation value of the pressure-sensitive adhesive layer or the adhesive layer used when the first optical compensation layer is laminated on the polarizing element or the second optical compensation layer is as small as possible.

The total thickness of the first optical compensation layer is preferably 5 to 200 μm, more preferably 10 to 100 μm, and most preferably 15 to 50 μm. , it is excellent in handling properties during manufacturing, and optical uniformity such as a value of retardation can be improved.

As a retardation film used for the 1st optical compensation layer, it is excellent in transparency, mechanical strength, thermal stability, moisture-shielding property, etc., and it is preferable that it is hard to produce optical nonuniformity by deformation|transformation. As said retardation film, the stretched film of the polymer film which has a thermoplastic resin as a main component is used preferably. As used herein, the term "stretched film" refers to a plastic film in which the orientation of molecules in a specific direction is increased by applying tension to an unstretched film at an appropriate temperature or by further applying tension to a previously stretched film.

The transmittance of the retardation film measured with light having a wavelength of 590 nm is preferably 80% or more, more preferably 85% or more, and particularly preferably 90% or more. Although the theoretical upper limit of the light transmittance is 100%, since the surface reflection occurs due to the difference in refractive index between air and the film, the feasible upper limit of the light transmittance is approximately 94%. In addition, it is preferable to have the same transmittance as the whole of the first optical compensation layer.

The absolute value of the photoelastic coefficient of the retardation film ^{is preferably 1.0×10 -10} m2/N or less, more preferably 5.0×10 ^-11 m2/N or less, and even more preferably 3.0×10 ^-11 m2/N or less, ^{It is especially preferable that it is 1.0x10-11} m<2>/N or less. By setting the value of the photoelastic coefficient in the above range, it is possible to obtain a liquid crystal display device having excellent optical uniformity, small change in optical properties even in environments such as high temperature and high humidity, and excellent durability. In addition, although the lower limit in particular of a photoelastic coefficient is not restrict|limited, Generally, it is ^5.0x10-13 m<2>/N or more, and ^{it is preferable that it is 1.0x10-12} m<2>/N or more. When the photoelastic coefficient is excessively small, since the appearance property of retardation tends to become small _{, it may become difficult to make front retardation Re 1} (590) into the range similar to said Formula (1). Although the photoelastic coefficient is a value inherent in chemical structures such as polymers, the photoelastic coefficient can be suppressed low by copolymerizing or mixing a plurality of components having different signs (yin and positive) of the photoelastic coefficient.

The thickness of the retardation film may be appropriately selected depending on the material used for the retardation film or the laminate structure of the optical compensation layer, and when the first optical compensation layer is composed of the retardation film alone, 5 to 300 μm, more preferably is 10 to 200 μm, most preferably 15 to 100 μm. If it is said range, it can be set as the retardation film excellent in mechanical strength and display uniformity.

As a method of obtaining a polymer film containing the thermoplastic resin as a main component, any suitable molding processing method is used, for example, compression molding, transfer molding, injection molding, extrusion molding, blow molding, powder molding, FRP molding, solvent casting, etc. are suitable. A suitable one can be selected. Among these manufacturing methods, the extrusion molding method or the solvent casting method is preferably used. It is because the retardation film which has high smoothness and favorable optical uniformity can be obtained. More specifically, in the extrusion molding method, a resin composition containing a thermoplastic resin, a plasticizer, an additive, etc. as a main component is heated and melted, and this is extruded into a thin film on the surface of a casting roll by a T-die or the like, and cooled to form a film method of manufacturing. In addition, in the solvent casting method, a thick solution (doping solution) obtained by dissolving a resin composition containing a thermoplastic resin, a plasticizer, an additive, etc. as a main component in a solvent is defoamed, and a metal endless belt or rotary drum, or plastic It is a method of manufacturing a film by uniformly casting a thin film on the surface of a substrate or the like and evaporating a solvent. In addition, molding conditions may be appropriately selected according to the composition or type of the resin to be used, molding processing method, and the like.

Although it does not specifically limit as a material which forms the said thermoplastic resin, For the _{purpose of obtaining the negative biaxial plate which satisfy|fills the characteristic of Nz 1} >1, it is preferable to use the polymer which has positive birefringence.

Here, "having positive birefringence" means that, when a polymer is oriented by stretching or the like, the refractive index in the orientation direction becomes relatively large, and many polymers correspond to this. Examples of the polymer having positive birefringence include cellulose fatty acid esters such as polycarbonate resins, polyvinyl alcohol resins, triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose and dipropionyl cellulose, or cellulose ethers such as cellulose ethers. Resin, polyester resin such as polyethylene terephthalate or polyethylene naphthalate, polyarylate resin, polyimide resin, cyclic polyolefin (polynorbornene) resin, polysulfone resin, polyethersulfone resin, polyamide and polyolefin-based resins such as resin and polyethylene and polypropylene. These polymers may be used individually by 1 type, and may mix and use 2 or more types. In addition, these may be modified and used by copolymerization, branching, crosslinking, molecular terminal modification (or sealing), stereoregular modification, or the like.

The polymer film containing the thermoplastic resin as a main component may further contain any appropriate additives, if necessary. Specific examples of the additive include a plasticizer, a heat stabilizer, a light stabilizer, a lubricant, an antioxidant, an ultraviolet absorber, a flame retardant, a colorant, an antistatic agent, a compatibilizer, a crosslinking agent, and a thickener. The type and amount of the additive used may be appropriately set according to the purpose. The amount of the additive used is typically 10 parts by weight based on 100 parts by weight of the total solid content of the polymer film. When the usage-amount of an additive becomes large excessively, transparency of a film may be impaired, or an additive may ooze out from the film surface.

Any suitable stretching method may be employed as a method for forming the stretched film of the polymer film. Specific examples thereof include a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse sequential biaxial stretching method, and a longitudinal and transverse simultaneous biaxial stretching method. As the stretching means, any suitable stretching machine, such as a roll stretching machine, a tenter stretching machine, a pantograph type, or a linear motor type biaxial stretching machine, can be used. When extending|stretching while heating, you may change the temperature continuously, and you may change it stepwise. Moreover, you may divide|segment an extending|stretching process into two or more times. From a viewpoint of obtaining a biaxial retardation film, the transverse uniaxial stretching method, the longitudinal/horizontal sequential biaxial stretching method, and the longitudinal/horizontal simultaneous biaxial stretching method can be used suitably.

In a polymer having positive birefringence, as described above, the refractive index in the orientation direction is relatively large, so in the case of the transverse uniaxial stretching method, it has a slow axis in the direction orthogonal to the conveying direction of the film, that is, in the width direction of the film ( In other words, the refractive index in the width direction becomes nx ₁ ). In the case of the longitudinal/horizontal sequential biaxial stretching method and the longitudinal/horizontal simultaneous biaxial stretching method, either one of the conveyance direction and the width direction may be set as the slow axis according to the ratio of the draw ratios of length and width. That is, when the draw ratio in the vertical (carrying) direction is relatively large, the vertical (carrying) direction becomes the slow axis, and when the draw ratio in the horizontal (width) direction is relatively large, the horizontal (width) direction becomes the slow axis.

As to which of the film transport direction and the width direction it is preferable to stretch so that it becomes the slow axis, although it differs depending on the structure of a liquid crystal panel, the slow axis of the 1st optical compensation layer and the slow axis of the said 2nd optical compensation layer are parallel. From the viewpoint of making it possible, it is preferable to adjust so that both slow-axis directions become the same. That is, when the second optical compensation layer has a slow axis in the film transport direction, it is preferable that the first optical compensation layer also has a slow axis in the film transport direction, and when the second optical compensation layer has a slow axis in the film width direction, , it is preferable that the first optical compensation layer also has a slow axis in the film width direction. By adjusting the direction of the slow axis in this way, since both can be laminated by a roll-to-roll and a laminate with a parallel slow axis can be obtained, productivity is excellent.

When stretching the polymer film, the temperature in the stretching oven (also referred to as stretching temperature) is preferably in the vicinity of the glass transition temperature (Tg) of the polymer film. Specifically, it is preferable that it is Tg-10 degreeC - Tg+30 degreeC, It is more preferable that it is Tg-Tg+25 degreeC, It is still more preferable that it is Tg+5 - Tg+20 degreeC. When extending|stretching temperature is too low, there exists a tendency for a retardation value or the direction of a slow axis to become non-uniform|heterogenous in the width direction, or it exists in the tendency for a film to crystallize (cloudiness) easily. Moreover, when extending|stretching temperature is too high, there exists a tendency for a film to melt|dissolve or expression of retardation becomes inadequate. The stretching temperature is typically in the range of 110 to 200°C. In addition, a glass transition temperature can be calculated|required by the DSC method according to JISK7121-1987.

A specific method for controlling the temperature in the stretching oven is not particularly limited, and there is no particular limitation on the air circulation type constant temperature oven in which hot or cold air circulates, a heater using microwaves or far infrared rays, etc., a roll heated for temperature control, a heat pipe roll, or a metal It can select suitably from the heating method, such as a belt, and the temperature control method.

The draw ratio when stretching the polymer film is determined from the composition of the polymer film, the type of volatile component, the residual amount of the volatile component, etc., the value of the designed retardation, etc., but is not particularly limited, for example, 1.05 to 5.00 times is preferably used. In addition, although there is no restriction|limiting in particular at the time of the conveying speed at the time of extending|stretching, From the viewpoint of the mechanical precision of an extending|stretching apparatus, stability, etc., Preferably it is 0.5-20 m/min.

As the retardation film used for the first optical compensation layer, a commercially available optical film in addition to those described above may be used as it is. Moreover, you may use, after giving secondary processing, such as an extending|stretching process and/or a relaxation process, to a commercially available optical film.

(Second Optical Compensation Layer)

The second optical compensation layer _{satisfies Nz 1} <-1 as described above. Such a retardation film may be called a "positive biaxial plate" or a "positive biaxial plate" in some cases.

The second optical compensation layer preferably satisfies the following formulas (2) and (4).

20 nm<Re ₂ (590)≤60 nm (2)

-4<Nz ₂ <-1 (4)

_{The front retardation Re 2} (590) of the second optical compensation layer is more preferably 21 to 59 nm, still more preferably 25 to 55 nm, particularly preferably 30 to 50 nm.

Further, _{the value of Nz 2} is more preferably -3.5 to -1.5, still more preferably -3.3 to -1.8, and particularly preferably -3.0 to -2.0.

In addition, the second optical compensation layer preferably satisfies the following formula (6).

-150 nm≤Rth ₂ (590)≤-60 nm (6)

Here, Rth ₂ (590) = Re ₂ (590) x (Nz ₂ -0.5), indicating retardation in the thickness direction.

_{The retardation Rth 2} in the thickness direction of the second optical compensation layer is more preferably -140 to -70 nm, still more preferably -130 to -80 nm, particularly preferably -120 to -85 nm.

It is preferable to satisfy the addition, the first optical compensation layer frontal retardation Re ₂ (590) and formula (7) to the front of the retardation Re ₂ (590) of the second optical compensation layer.

110 nm<Re ₁ (590)+Re ₂ (590)<150 nm (7)

The sum of Re ₁ (590) and Re ₂ (590) is more preferably 115 to 145 nm, still more preferably 120 to 140 nm, particularly preferably 125 to 135 nm.

The material and manufacturing method of the second optical compensation layer are not particularly limited as long as the above-described optical properties are satisfied. The second optical compensation layer may be a single retardation film or a laminate of two or more retardation films. Preferably, the second optical compensation layer is a single retardation film. This is because the liquid crystal panel can be thinned by reducing the shift or non-uniformity of the retardation value due to the shrinkage stress of the polarizing element or the heat of the light source. When the second optical compensation layer is a laminate, an adhesive layer or an adhesive layer for bonding two or more retardation films may be included. When the laminate includes two or more retardation films, these retardation films may be the same or different.

The optical characteristics of the retardation film used for the second optical compensation layer may be appropriately selected according to the number of retardation films used. For example, when the second optical compensation layer is constituted by the retardation film alone, the front retardation and the thickness direction retardation of the retardation film are respectively the front retardation Re ₂ and the thickness direction retardation Rth ₂ of the second optical compensation layer The same is preferable. Accordingly, it is preferable that the retardation value of the pressure-sensitive adhesive layer or the adhesive layer used in laminating the second optical compensation layer on the polarizing element or the second optical compensation layer is as small as possible.

As the retardation film used for the second optical compensation layer, similar to the retardation film used for the first optical compensation layer, it is excellent in transparency, mechanical strength, thermal stability, moisture shielding property, etc., and is difficult to cause optical unevenness due to deformation. It is preferably used. As said retardation film, the stretched film of the polymer film which has a thermoplastic resin as a main component is used preferably. The thickness, transmittance, photoelastic coefficient, and molding method thereof of such a film are not particularly limited, but it is preferably within the same range as that of the substrate in the first optical compensation layer.

Although it does not specifically limit as a material which forms the said thermoplastic resin, In order _{to obtain the positive biaxial plate which satisfy|fills the characteristic of Nz 2} <-1, it is preferable to use the polymer which has negative birefringence.

Here, "having negative birefringence" means that when the polymer is oriented by stretching or the like, the refractive index in the orientation direction becomes relatively small, in other words, the refractive index in the direction orthogonal to the orientation direction increases. Examples of such a polymer include those in which a chemical bond or functional group having high polarization anisotropy such as an aromatic or a carbonyl group is introduced into the side chain of the polymer. Specific examples thereof include acrylic resins, styrene resins, and maleimide resins.

As a manufacturing method of the above-mentioned acrylic resin, a styrene resin, and a maleimide resin, it can obtain, for example by addition polymerization of an acrylic monomer, a styrene monomer, a maleimide monomer, etc. respectively. Moreover, the birefringence characteristic can also be controlled by substituting a side chain after superposition|polymerization, or performing maleimidization or grafting reaction.

Examples of the acrylic resin include polymethyl methacrylate (PMMA), polybutyl methacrylate, and polycyclohexyl methacrylate.

Examples of the styrene-based monomer as the raw material monomer for the styrene-based resin include styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, and p-carboxystyrene. , p-phenylstyrene, 2,5-dichlorostyrene, pt-butylstyrene, and the like.

Examples of the raw material monomer for the maleimide-based resin include N-ethylmaleimide, N-cyclohexylmaleimide, N-phenylmaleimide, N-(2-methylphenyl)maleimide, and N-(2-ethylphenyl)maleimide. , N-(2-propylphenyl)maleimide, N-(2-isopropylphenyl)maleimide, N-(2,6-dimethylphenyl)maleimide, N-(2,6-dipropylphenyl)maleimide , N- (2,6-diisopropylphenyl) maleimide, N- (2-methyl-6-ethylphenyl) maleimide, N- (2-chlorophenyl) maleimide, N- (2,6-dichloro Phenyl), N-(2-bromophenyl)maleimide, N-(2,6-dibromophenyl)maleimide, N-(2-biphenyl)maleimide, N-(2-cyanophenyl) Maleimide etc. are mentioned. The maleimide-based monomer can be obtained from, for example, Tokyo Kasei Kogyo Co., Ltd. or the like.

The polymer exhibiting negative birefringence may be one in which another monomer is copolymerized for the purpose of improving brittleness, moldability, heat resistance, and the like. Other monomer components used for this purpose include, for example, ethylene, propylene, 1-butene, 1,3-butadiene, 2-methyl-1-butene, 2-methyl-1-pentene, 1-hexene, acrylonitrile, acrylic acid. Methyl, methyl methacrylate, maleic anhydride, vinyl acetate, etc. are mentioned.

When the polymer exhibiting negative birefringence is a copolymer of a styrenic monomer and another monomer, the content of the styrenic monomer component is preferably 50 to 80 mol%. When the polymer exhibiting negative birefringence is a copolymer of a maleimide-based monomer and another monomer, the content of the maleimide-based monomer component is preferably 2 to 50 mol%. If the content of the monomer component is within the above range, a film excellent in toughness and moldability can be obtained.

Among the polymers showing negative birefringence, styrene-maleic anhydride copolymer, acrylonitrile copolymer, styrene-(meth)acrylate copolymer, styrene-maleimide copolymer, vinyl ester-maleimide copolymer, olefin- A maleimide copolymer can be used suitably. These may be used individually by 1 type, and may mix and use 2 or more types. These polymers exhibit high negative birefringence and also have excellent heat resistance. These polymers can be obtained, for example, from Nova Chemicals Japan, Arakawa Kagaku Kogyo Co., Ltd. and the like.

Moreover, as a polymer which shows negative birefringence, the polymer which has a repeating unit represented by the following general formula (I) can also be used suitably. Such a polymer can be obtained by using, as a maleimide-based monomer as a starting material, an N-phenyl-substituted maleimide in which a phenyl group having a substituent at least at an ortho position is introduced as an N-substituent. These polymers have higher negative birefringence and also have excellent heat resistance and mechanical strength.

In the general formula (I), R ₁ to _{R 5} each independently represent hydrogen, a halogen atom, carboxylic acid, carboxylic acid ester, a hydroxyl group, a nitro group, or a linear or branched alkyl group or alkoxy group having 1 to 8 carbon atoms. (provided that R ₁ and R ₅ are not hydrogen atoms at the same time), R ₆ and R _{7 each} represent a hydrogen atom or a linear or branched alkyl or alkoxy group having 1 to 8 carbon atoms, and n represents an integer of 2 or more.

Moreover, as a polymer which shows negative birefringence, it is not limited to the above, For example, the cyclic olefin type copolymer etc. which are disclosed by Unexamined-Japanese-Patent No. 2005-350544 etc. can also be used. Furthermore, a composition of a polymer and inorganic fine particles as disclosed in JP-A-2005-156862 and JP-A-2005-227427 can also be suitably used. In addition, the polymer showing negative birefringence may be used individually by 1 type, and may be used in mixture of 2 or more types. In addition, these may be modified and used by copolymerization, branching, crosslinking, molecular terminal modification (or sealing), stereoregular modification, or the like.

The polymer film containing the thermoplastic resin as a main component may further contain any appropriate additives, if necessary, as described above for the first optical compensation layer.

As a method of forming the stretched film of the polymer film, any suitable stretching method may be employed as described above for the first optical compensation layer.

In a polymer having negative birefringence, as described above, the refractive index in the orientation direction is relatively small, so in the case of the transverse uniaxial stretching method, the film has a slow axis in the transport direction (in other words, the refractive index in the transport direction is nx ₁ becomes). In the case of the longitudinal/horizontal sequential biaxial stretching method and the longitudinal/horizontal simultaneous biaxial stretching method, either of the conveyance direction and the width direction may be set as the slow axis according to the ratio of the longitudinal/horizontal draw ratios. That is, when the draw ratio in the vertical (conveyance) direction is relatively large, the horizontal (width) direction becomes the slow axis, and when the draw ratio in the horizontal (width) direction is relatively large, the vertical (transport) direction becomes the slow axis.

The stretching temperature, the temperature control method in the stretching oven, the stretching ratio, etc. are not particularly limited, and the same stretching temperature, temperature control method, and stretching ratio as those of the substrate in the first optical compensation layer can be suitably applied.

In the above, a method for obtaining a positive biaxial plate used for the second optical compensation layer using a polymer having a negative birefringence has been described. However, the positive biaxial plate can also be manufactured using a polymer having a positive birefringence. .

As a method of obtaining a positive biaxial plate using a polymer having positive birefringence, for example, those disclosed in Japanese Patent Laid-Open Nos. 2000-231016, 2000-206328, and 2002-207123 Similarly, the stretching method of increasing the refractive index in the thickness direction can be used. That is, a heat-shrinkable film is adhered to one or both sides of a film having a polymer having a positive birefringence, and a film having a polymer having a positive birefringence under the action of a contracting force of the heat-shrinkable film by heat treatment is contracted, the film A positive biaxial plate satisfying the characteristic of _{Nz 2} >-1 can be obtained by increasing the refractive index in the thickness direction by shrinking both the longitudinal and transverse directions of .

As described above, the positive biaxial plate used as the second optical compensation layer can be manufactured using a polymer having both negative and positive birefringence, but in general, when a positive birefringent polymer is used, selectable polymers are It has an advantage in that there are many types, and when a negative birefringent polymer is used, compared to a case where a positive birefringent polymer is used, due to the stretching method, a retardation film with high uniformity in the slow axis direction can be easily obtained. It has an advantage in that

As the retardation film used for the second optical compensation layer, a commercially available optical film other than the above-mentioned may be used as it is. Moreover, you may use, after giving secondary processing, such as an extending|stretching process and/or a relaxation process, to a commercially available optical film.

Lamination of the polarizing element, the first optical compensation layer, and the second optical compensation layer is performed using an adhesive or pressure-sensitive adhesive, which will be described later. Moreover, you may arrange|position the optically isotropic film mentioned later between a polarizing element and a 1st optical compensation layer. Lamination of the polarizing element, the optically isotropic film, and the optically isotropic film and the first optical compensation layer is also performed using an adhesive or pressure-sensitive adhesive, which will be described later.

When a polarizing plate provided with such an optical compensation film is applied to a liquid crystal cell of O-mode IPS mode, the polarizing plate of the present invention is preferably disposed on the viewing side of the liquid crystal display device. Moreover, when applying to the liquid crystal cell of IPS mode of E mode, it is preferable that the polarizing plate of this invention is arrange|positioned on the light source side of a liquid crystal display device.

In addition, when the polarizing plate of the present invention is laminated on one side of the liquid crystal display device in IPS mode, the polarizing plate laminated on the other side of the liquid crystal cell is a polarizing plate in which a polarizing element and an optically isotropic film are laminated, and the optical isotropy The structure in which the film side is laminated|stacked on the liquid crystal cell via an adhesive is preferable.

An optically isotropic film means the thing which satisfy|fills following formula (8) and (9).

0 nm≤|Re ₃ (590)|≤20 nm (8)

0 nm≤|Rth ₃ (590)|≤20 nm (9)

Here, when the refractive index in the in-plane slow axis direction of the optically isotropic film is nx ₃ , the in-plane refractive index in the fast axis direction is ny ₃ , and the refractive index in the thickness direction is nz ₃ , Re ₃ (λ) = (nx ₃ -ny ₃ )×d ₃ , Rth ₃ (λ)={(nx ₃ +ny ₃ )/2-nz}×d ₃ , and d ₃ represents the thickness of the optically isotropic film.

There is no restriction|limiting in particular as long as the material, manufacturing method, etc. of an isotropic optical element satisfy|fill the above-mentioned optical characteristic. A single optical film may be sufficient as the said isotropic optical element, and the laminated body of two or more optical films may be sufficient as it. Preferably the isotropic optical element is a single film. This is because the liquid crystal panel can be made thin by reducing the occurrence and non-uniformity of birefringence due to the shrinkage stress of the polarizing element or the heat of the light source. When the isotropic optical element is a laminate, an adhesive layer or an adhesive layer for bonding two or more retardation films may be included. When the laminate includes two or more retardation films, these retardation films may be the same or different. For example, when laminating two retardation films, the retardation films are preferably arranged so that their respective slow axes are orthogonal to each other. By arranging in this way, the in-plane retardation value can be made small. Moreover, it is preferable that each retardation film laminates|stacks the film in which the negative and positive of the retardation value of the thickness direction are mutually opposite. By laminating in this way, the retardation value in the thickness direction can be made small.

As an optical film used for an isotropic optical element, it is excellent in transparency, mechanical strength, thermal stability, moisture shielding property, etc., similarly to the retardation film used for the said 1st and 2nd optical compensation layers, and optical nonuniformity is produced by denaturation. The difficult one is preferably used. A polymer film is preferably used as the film. The thickness, transmittance, and molding method of such a film are not particularly limited, but it is preferably within the same range as that of the substrate in the first optical compensation layer.

The absolute value of the photoelastic coefficient of the optical film used for the isotropic optical element ^{is preferably 1.0×10 -10} m2/N or less, more preferably 5.0×10 ^-11 m2/N or less, and 1.0×10 ^-11 m2/N or less. It is more preferable, and ^{it is especially preferable that it is 5.0x10 -12} m<2>/N or less. By setting the value of the photoelastic coefficient in the above range, it is possible to obtain a liquid crystal display device having excellent optical uniformity, small change in optical properties even in environments such as high temperature and high humidity, and excellent durability. In addition, although the lower limit in particular of a photoelastic coefficient is not restrict|limited, Generally, it is 5.0x10 ^-13 m<2>/N or more. The value of the photoelastic coefficient can be kept low by the same method as described above for the first optical compensation layer.

As a material constituting the optical isotropic film, polycarbonate-based resin, polyvinyl alcohol-based resin, cellulose-based resin, polyester-based resin, polyarylate-based resin, polyimide-based resin, cyclic polyolefin-based resin, polysulfone-based resin, and polyethersulfone-based resins, polyolefin-based resins, polystyrene-based resins, polyvinyl alcohol-based resins, and mixtures thereof. Moreover, thermosetting resins, such as urethane type, acrylic urethane type, epoxy type, silicone type, or ultraviolet curable resin can also be used. In the optically isotropic film, one or more kinds of any appropriate additives may be included in the same manner as in the first and second optical compensation layers.

As said cellulosic resin, the ester of a cellulose and a fatty acid is preferable. Specific examples of such a cellulose ester-based resin include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, and dipropionyl cellulose. Among these, triacetyl cellulose is especially preferable. Many products are marketed, and triacetyl cellulose is advantageous also from the point of availability and cost. In many cases, triacetyl cellulose has a thickness direction retardation (Rth) exceeding 10 nm, but an additive that cancels out these retardation is used, or a cellulose resin having a small thickness direction retardation as well as front retardation by a film forming method. film can be obtained. As the above-mentioned film forming method, for example, a base film of polyethylene terephthalate, polypropylene, stainless steel, etc. coated with a solvent such as cyclopentanone or methyl ethyl ketone is bonded to a general cellulose-based film and dried by heating (e.g., at 80 to 150°C). 3 to 10 minutes or so), and then the method of peeling the base film; A solution obtained by dissolving norbornene-based resin, (meth)acrylic resin, etc. in a solvent such as cyclopentanone or methyl ethyl ketone is coated on a general cellulose-based resin film and dried by heating (e.g., at 80 to 150° C. for 3 to 10 minutes) After carrying out, the method of peeling a coating film, etc. are mentioned.

Moreover, as a cellulose-type resin film with a small thickness direction retardation, the fatty-acid cellulose-type resin film which controlled the fat substitution degree can be used. Although the degree of acetic acid substitution is about 2.8 in triacetyl cellulose generally used, Rth can be made small by controlling the degree of acetic acid substitution preferably to 1.8 to 2.7. Rth can be controlled small by adding plasticizers, such as dibutyl phthalate, p-toluenesulfonanilide, and acetyl triethyl citrate, to the said fatty-acid-substituted cellulose resin. The amount of the plasticizer to be added is preferably 40 parts by weight or less, more preferably 1 to 20 parts by weight, and still more preferably 1 to 15 parts by weight based on 100 parts by weight of the fatty acid cellulose-based resin.

Further, as an optically isotropic film, a thermoplastic resin having a substituted and/or unsubstituted imide group in the side chain described in JP-A-2001-343529 (WO01/37007) etc., a substituted and/unsubstituted phenyl, and a nitrile group in the side chain A polymer film containing a resin composition containing a thermoplastic resin having , a polymer film containing an acrylic resin having a lactone ring structure described in Japanese Patent Laid-Open No. 2005-146084, Japanese Patent Laid-Open No. 2006-171464, etc., Japanese Patent Laid-Open Nos. 2004-70290 and 2004-70296 , Japanese Unexamined Patent Application Publication No. 2004-163924, Japanese Unexamined Patent Application Publication No. 2004-292812, Japanese Unexamined Patent Application Publication No. 2005-314534, Japanese Unexamined Patent Application Publication No. 2006-131898, Japanese Unexamined Patent Application Publication No. 2006-206881, Japanese Unexamined Patent Publication No. 2006 Structural units of unsaturated carboxylic acid alkyl esters and structural units of glutaric anhydride described in Japanese Patent Application Laid-Open Nos. - 265532, 2006-283013, 2006-299005, and 2006-335902, etc. A polymer film containing an acrylic resin having A film containing a thermoplastic resin having a glutarimide structure described in Japanese Patent Application Laid-Open No. -337491, 2006-337492, JP 2006-337493 , JP 2006-337569 , etc. can also be used. . These films have small front retardation and thickness direction retardation and also have a small photoelastic coefficient, so even when the polarizing plate is deformed by heating, etc., problems such as non-uniformity do not easily occur, and the moisture permeability is small, so it is excellent in humidification durability. preferred in that respect.

Moreover, it is also preferable to use cyclic polyolefin resin as an optically isotropic film. As a specific example of cyclic polyolefin-type resin, Preferably it is norbornene-type resin. Cyclic polyolefin-based resin is a generic term for resins polymerized using cyclic olefin as a polymerization unit, for example, in Japanese Patent Application Laid-Open Nos. 1-240517, Hei 3-14882, and Japanese Patent Laid-Open No. 3-122137. Resins described in etc. are mentioned. Specific examples include ring-opened (co)polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene and copolymers thereof (typically random copolymers), and unsaturated carboxylic acids and derivatives thereof and graft polymers modified with , and hydrides thereof. A norbornene-type monomer is mentioned as a specific example of a cyclic olefin.

Various products are marketed as cyclic polyolefin resin. Specific examples include "Zeonoa" manufactured by Nippon Zeon Co., Ltd. under the trade name "Aton", manufactured by JSR Corporation under the trade name "Topas", and Mitsui Chemicals Ltd. under the trade name "Apel". can

An adhesive agent or a pressure-sensitive adhesive, which will be described later, can also be used for lamination of the polarizing element and the optically isotropic film.

<Adhesive layer>

Any suitable adhesive may be used as the adhesive constituting the adhesive layer for bonding the protective film to the polarizing element. Although a water-based adhesive agent, a solvent-type adhesive agent, an active-energy-ray-curable adhesive agent, etc. can be used as an adhesive agent, It is preferable that it is a water-based adhesive agent. The adhesive layer contains at least one urea compound preferably selected from urea, urea derivatives, thiourea and thiourea derivatives from the viewpoint of improving heat resistance.

The thickness at the time of adhesive application can be set to any suitable value. For example, it is set so that an adhesive layer having a desired thickness can be obtained after curing or after heating (drying). The thickness of the adhesive layer is preferably 0.01 µm or more and 7 µm or less, more preferably 0.01 µm or more and 5 µm or less, still more preferably 0.01 µm or more and 2 µm or less, and most preferably 0.01 µm or more and 1 µm or less. am.

(Water-Based Adhesive)

Any suitable water-based adhesive may be employed as the water-based adhesive. Among them, a water-based adhesive (PVA-based adhesive) containing a PVA-based resin is preferably used. The average degree of polymerization of the PVA-based resin contained in the water-based adhesive is preferably about 100 to 5500, more preferably about 1000 to 4500 from the viewpoint of adhesiveness. The average degree of saponification is preferably about 85 mol% to 100 mol%, more preferably 90 mol% to 100 mol% from the viewpoint of adhesiveness.

The PVA-based resin contained in the water-based adhesive preferably contains an acetoacetyl group, because the PVA-based resin layer and the protective film have excellent adhesion and durability. The acetoacetyl group-containing PVA-based resin can be obtained, for example, by reacting the PVA-based resin with diketene by any method. The degree of acetoacetyl group modification of the acetoacetyl group-containing PVA-based resin is typically 0.1 mol% or more, and preferably about 0.1 mol% to 20 mol%.

The resin concentration of the water-based adhesive is preferably 0.1 mass% to 15 mass%, more preferably 0.5 mass% to 10 mass%.

The water-based adhesive may contain a crosslinking agent. As a crosslinking agent, a well-known crosslinking agent can be used. For example, a water-soluble epoxy compound, dialdehyde, isocyanate, etc. are mentioned.

When the PVA-based resin is an acetoacetyl group-containing PVA-based resin, the crosslinking agent is preferably any one of glyoxal, glyoxylate, and methylolmelamine, and preferably any one of glyoxal and glyoxylate, and It is particularly preferred that it is oxal.

The water-based adhesive may contain an organic solvent. Since the organic solvent has miscibility with water, alcohols are preferable, and among alcohols, methanol or ethanol is more preferable. Some of the urea-based compounds have low solubility in water, while some have sufficient solubility in alcohol. In that case, it is also one of preferred embodiments to prepare an adhesive by dissolving the urea compound in alcohol to prepare an alcohol solution of the urea compound, and then adding the alcohol solution of the urea compound to the PVA aqueous solution.

The methanol concentration of the water-based adhesive is preferably 10% by mass or more and 70% by mass or less, more preferably 15% by mass or more and 60% by mass or less, and still more preferably 20% by mass or more and 60% by mass or less. When the concentration of methanol is 10 mass % or more, it becomes easy to suppress polyenization in a high temperature environment more. Moreover, deterioration of a hue can be suppressed because the content rate of methanol is 70 mass % or less.

(Active energy ray-curable adhesive)

An active energy ray-curable adhesive is an adhesive that is cured by irradiating active energy rays such as ultraviolet rays, for example, an adhesive containing a polymerizable compound and a photopolymerization initiator, an adhesive containing a photoreactive resin, a binder resin, and a photoreactive crosslinking agent. and adhesives. Examples of the polymerizable compound include photopolymerizable monomers such as photocurable epoxy monomers, photocurable acrylic monomers and photocurable urethane monomers, and oligomers derived from these monomers. As said photoinitiator, the compound containing the substance which irradiates active energy rays, such as an ultraviolet-ray, to generate|occur|produce active species, such as a neutral radical, an anion radical, and a cationic radical, is mentioned.

(Urea compound)

When the adhesive layer contains a urea-based compound, the urea-based compound is at least one selected from urea, urea derivatives, thiourea and thiourea derivatives. As a method of containing the urea compound in the adhesive layer, it is preferable to contain the urea compound in the above adhesive. In addition, in the process of forming an adhesive bond layer from an adhesive agent through a drying process etc., a part of a urea type compound may move from an adhesive bond layer to a polarizing element etc. That is, the polarizing element may contain a urea compound. There are water-soluble and poorly water-soluble urea compounds, and any urea-based compound can be used in the adhesive of the present embodiment. When the poorly water-soluble urea-based compound is used in a water-based adhesive, it is preferable to adopt a dispersion method so that haze does not occur after the adhesive layer is formed.

When the adhesive is a water-based adhesive containing a PVA-based resin, the amount of the urea-based compound added is preferably 0.1 to 400 parts by mass, more preferably 1 to 200 parts by mass, and 3 to 100 parts by mass relative to 100 parts by mass of the PVA resin. It is more preferable to deny it.

(urea derivatives)

A urea derivative is a compound in which at least one of the four hydrogen atoms of the urea molecule is substituted with a substituent. In this case, although there is no restriction|limiting in particular in a substituent, It is preferable that it is a substituent containing a carbon atom, a hydrogen atom, and an oxygen atom.

Specific examples of the urea derivative include methyl urea, ethyl urea, propyl urea, butyl urea, isobutyl urea, N-octadecyl urea, 2-hydroxyethyl urea, hydroxy urea, acetyl urea, and allyl urea. , 2-propynyl urea, cyclohexyl urea, phenyl urea, 3-hydroxyphenyl urea, (4-methoxyphenyl) urea, benzyl urea, benzoyl urea, o-tolyl urea, and p-tolyl urea.

2 As the substituted element, 1,1-dimethyl urea, 1,3-dimethyl urea, 1,1-diethyl urea, 1,3-diethyl urea, 1,3-bis(hydroxymethyl) urea, 1,3 -tert-butylurea, 1,3-dicyclohexylurea, 1,3-diphenylurea, 1,3-bis(4-methoxyphenyl)urea, 1-acetyl-3-methylurea, 2-imida and zolidinone (ethylene urea) and tetrahydro-2-pyrimidinone (propylene urea).

4 Substituting elements include tetramethyl urea, 1,1,3,3-tetraethyl urea, 1,1,3,3-tetrabutyl urea, 1,3-dimethoxy-1,3-dimethyl urea, 1,3 -dimethyl-2-imidazolidinone and 1,3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone.

(thiourea derivatives)

A thiourea derivative is a compound in which at least one of the four hydrogen atoms of a thiourea molecule is substituted with a substituent. In this case, although there is no restriction|limiting in particular in a substituent, It is preferable that it is a substituent containing a carbon atom, a hydrogen atom, and an oxygen atom.

Specific examples of the thiourea derivative include, as monosubstituted thiourea, N-methylthiourea, ethylthiourea, propylthiourea, isopropylthiourea, 1-butylthiourea, cyclohexylthiourea, N-acetylthiourea, N-allylthiourea, (2-methoxyethyl)thiourea, N-phenylthiourea, (4-methoxyphenyl)thiourea, N-(2-methoxyphenyl)thiourea, N-(1-naph tyl)thiourea, (2-pyridyl)thiourea, o-tolylthiourea, and p-tolylthiourea are mentioned.

Examples of the 2-substituted thiourea include 1,1-dimethylthiourea, 1,3-dimethylthiourea, 1,1-diethylthiourea, 1,3-diethylthiourea, 1,3-dibutylthiourea, and 1 ,3-diisopropylthiourea, 1,3-dicyclohexylthiourea, N,N-diphenylthiourea, N,N'-diphenylthiourea, 1,3-di(o-tolyl)thiourea , 1,3-di(p-tolyl)thiourea, 1-benzyl-3-phenylthiourea, 1-methyl-3-phenylthiourea, N-allyl-N'-(2-hydroxyethyl)thiourea , and ethylenethiourea.

Trimethylthiourea is mentioned as a tri-substituted thiourea, and tetramethylthiourea and 1,1,3,3-tetraethylthiourea are mentioned as a 4-substituted thiourea.

Among the urea compounds, a urea derivative or a thiourea derivative is preferable, and a urea derivative is more preferable from the viewpoint that a decrease in transmittance in a high-temperature environment can be further suppressed when used in an image display device having an interlayer filling configuration. Among the urea derivatives, mono- or di-substituted elements are preferable, and mono-substituted elements are more preferable. The two-substituted element includes a 1,1-substituted element and a 1,3-substituted element, but the 1,3-substituted element is more preferred.

<Layer containing urea compound>

The urea compound is not limited to the case where it is contained in the adhesive layer as described above, and may be contained in a layer other than the adhesive layer from the viewpoint of improving the heat resistance of the polarizing plate. As the other layer, as described in the description of the transparent protective film, a polarizing plate having a protective film on only one side of the polarizing element has been developed in order to meet the demand for thinning the polarizing plate in recent years. Such a structure WHEREIN: For the purpose of raising physical strength, etc., you may laminate|stack a hardened layer on the surface which does not have a protective film of a polarizing element.

In the present embodiment, such a cured layer may contain a urea compound. Usually, such a cured layer is formed of a curable composition containing an organic solvent, and in paragraphs [0020] to [0042] of Japanese Patent Application Laid-Open No. 2017-075986, a method for forming such a cured layer from a physical solution of an active energy ray-curable polymer composition A method is described. Since many urea-based compounds are water-soluble, such a composition may contain a water-soluble urea-based compound.

<moisture content>

(Feature (a))

In the case of having the characteristic (a), the moisture content of the polarizing element is equal to or higher than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 30% and equal to or less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%. More preferably, the equilibrium moisture content is less than or equal to the equilibrium moisture content at a temperature of 20 ° C. relative humidity of 45%, more preferably the equilibrium moisture content is less than or equal to the equilibrium moisture content at a temperature of 20 ° C. . When the temperature is less than the equilibrium moisture content of 20°C and 30% relative humidity, the handling property of the polarizing element is lowered and the polarizing element is easily broken. When the moisture content of the polarizing element exceeds the equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%, the transmittance of the polarizing element tends to decrease. When the water content of a polarizing element is high, it is estimated that it is because polyenization of PVA-type resin will advance easily. The moisture content of the polarizing element is the moisture content of the polarizing element in the polarizing plate.

As a method of confirming whether the moisture content of the polarizing element is within the range of an equilibrium moisture content of 30% or more of a temperature of 20 ° C. and a relative humidity of 30% and less than an equilibrium moisture content of a temperature of 20 ° C. of 50% of the relative humidity, adjusted to the range of the temperature and the relative humidity When the polarizing element is stored in the environment and there is no change in mass for a certain period of time, it can be considered to have reached equilibrium with the environment, or by calculating in advance the equilibrium moisture content of the polarizing element in the environment adjusted to the range of the temperature and the relative humidity. , can be confirmed by comparing the moisture content of the polarizing element with the equilibrium moisture content calculated in advance.

A method for manufacturing a polarizing device having a moisture content equal to or higher than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 30% and less than or equal to an equilibrium moisture content at a temperature of 20°C and a relative humidity of 50% is not particularly limited, for example, adjusted to the range of the temperature and the relative humidity The method of storing a polarizing element for 10 minutes or more and 3 hours or less, or the method of heat-processing at 30 degreeC or more and 90 degrees C or less is mentioned in the exposed environment.

As another preferred method for manufacturing the polarizing element having the above moisture content, a laminate in which a protective film is laminated on at least one surface of the polarizing element, or a polarizing plate composed of a polarizing element, is adjusted to the range of the temperature and the relative humidity. The method of storing in an environment for 10 minutes or more and 120 hours or less, or the method of heat-processing at 30 degreeC or more and 90 degrees C or less is mentioned. In the production of an image display device employing an interlayer charging configuration, an image display panel in which a polarizing plate is laminated on an image display cell is stored in an environment adjusted to the range of the temperature and the relative humidity for 10 minutes or more and 3 hours or less, or 30 After heating at °C or higher and 90 °C or lower, the front plate may be joined.

It is preferable that the moisture content of the polarizing element is adjusted so that the moisture content falls within the above numerical range at the stage of material used for constituting the polarizing plate, either alone or as a laminate of a polarizing element and a protective film. When a moisture content is adjusted after comprising a polarizing plate, curl becomes large too much, and when bonding to an image display cell, it may become easy to produce a malfunction. By constructing the polarizing plate using the polarizing element adjusted to the above-mentioned moisture content in the material step prior to forming the polarizing plate, a polarizing plate provided with the polarizing element whose moisture content satisfies the above numerical range can be easily constructed. In the state which bonded the polarizing plate to the image display cell, you may adjust so that the moisture content of the polarizing element in a polarizing plate may become the said numerical range. In this case, since the polarizing plate is bonded to the image display cell, curl is difficult to occur.

(Feature (b))

In the case of having the characteristic (b), the moisture content of the polarizing plate is equal to or greater than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 30% and equal to or less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%. The moisture content of the polarizing plate is preferably equal to or less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 45%, more preferably, the equilibrium moisture content at a temperature of 20°C and a relative humidity of 42% or less, and still more preferably at a temperature of 20°C and a relative humidity of 38%. below the equilibrium moisture content. When the moisture content of the polarizing plate is lower than the equilibrium moisture content of the temperature of 20°C and the relative humidity of 30%, the handling property of the polarizing plate is lowered, and thus the polarizing plate is easily broken. When the moisture content of the polarizing plate exceeds the equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%, the transmittance of the polarizing element tends to decrease. When the water content of a polarizing plate is high, it is estimated that it is because polyenization of PVA-type resin will advance easily.

As a method of confirming whether the moisture content of the polarizing plate is within the range of an equilibrium moisture content of 30% or more of a temperature of 20 ° C. relative humidity and less than an equilibrium moisture content of a temperature of 20 ° C. of 50% of a relative humidity, an environment adjusted to the range of the temperature and the relative humidity If the polarizing plate is stored in the polarizer and there is no change in mass for a certain period of time, it can be considered to have reached equilibrium with the environment, or by calculating in advance the equilibrium moisture content of the polarizing plate in the environment adjusted to the range of the temperature and the relative humidity, It can be confirmed by comparing the moisture content with the pre-calculated equilibrium moisture content.

A method for producing a polarizing plate having a moisture content equal to or greater than the equilibrium moisture content at a temperature of 20 ° C. and a relative humidity of 30% and less than or equal to an equilibrium moisture content at a temperature of 20 ° C. The method of storing a polarizing plate in an environment for 10 minutes or more and 3 hours or less, or the method of heat-processing at 30 degreeC or more and 90 degrees C or less is mentioned.

In the production of an image display device employing an interlayer charging configuration, an image display panel in which a polarizing plate is laminated on an image display cell is stored in an environment adjusted to the range of the temperature and the relative humidity for 10 minutes or more and 3 hours or less, or 30 After heating at °C or higher and 90 °C or lower, the front plate may be joined.

[Manufacturing method of polarizing plate]

The manufacturing method of the polarizing plate of this embodiment has the lamination|stacking process of laminating|stacking a polarizing element and a transparent protective film, and a moisture content adjustment process. In the moisture content adjustment step, when a polarizing plate having the characteristic (a) is manufactured, the polarization element is polarized so that the moisture content of the polarizing element is equal to or higher than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 30% and equal to or less than the equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%. Adjust the moisture content of the device. The moisture content of the polarizing element can be adjusted as described in the above-mentioned moisture content of the polarizing element. In the moisture content adjustment step, when a polarizing plate having the characteristic (b) is manufactured, the moisture content of the polarizing plate is equal to or higher than the equilibrium moisture content at a temperature of 20 ° C. of 30% relative humidity, and less than or equal to the equilibrium moisture content at a temperature of 20 ° C. Adjust the moisture content. The moisture content of the polarizing plate can be adjusted as described in the above-mentioned moisture content of the polarizing plate. The order of the moisture content adjustment process and the lamination process is not limited, and the moisture content adjustment process and the lamination process may be performed in parallel. A lamination process can be made into the process of bonding a polarizing element and a transparent protective film through the said adhesive bond layer.

[Configuration of image display device]

The polarizing plate of this embodiment is used for various image display apparatuses, such as a liquid crystal display device and an organic electroluminescent display. Regarding an image display device, in the case of the interlayer filling structure in which both surfaces of a polarizing plate are comprised so that layers other than an air layer, specifically, solid layers, such as an adhesive layer, may contact, the transmittance|permeability falls easily under a high temperature environment. In the image display apparatus using the polarizing plate of this embodiment, even if it is an interlayer filling structure, the transmittance|permeability fall of the polarizing plate in a high-temperature environment can be suppressed. As an image display apparatus, the structure which has an image display cell, the 1st adhesive layer laminated|stacked on the surface of the visual recognition side of an image display cell, and the polarizing plate laminated|stacked on the surface by the visual recognition side of a 1st adhesive layer is illustrated. Such an image display apparatus may further have the 2nd adhesive layer laminated|stacked on the surface of the visual recognition side of a polarizing plate, and the transparent member laminated|stacked on the surface of the 2nd adhesive layer. In particular, in the polarizing plate of this embodiment, a transparent member is disposed on the visual recognition side of the image display device, the polarizing plate and the image display cell are bonded by a first adhesive layer, and the polarizing plate and the transparent member are bonded by a second adhesive layer. It is suitably used for the image display apparatus which has an interlayer filling structure. In this specification, either or both of a 1st adhesive layer and a 2nd adhesive layer may be called simply "a pressure-sensitive adhesive layer." In addition, as a member used for bonding of a polarizing plate and an image display cell, and a member used for bonding of a polarizing plate and a transparent member, it is not limited to an adhesive layer, An adhesive bond layer may be sufficient.

<Image display cell>

A liquid crystal cell and an organic electroluminescent cell are mentioned as an image display cell. As the liquid crystal cell, any of a reflective liquid crystal cell using external light, a transmissive liquid crystal cell using light from a light source such as a backlight, and a transflective liquid crystal cell using both external light and light from a light source may be used. . In the case where the liquid crystal cell uses light from a light source, in the image display device (liquid crystal display device), a polarizing plate is also disposed on the side opposite to the viewing side of the image display cell (liquid crystal cell), and a light source is further disposed thereon. The polarizing plate on the light source side and the liquid crystal cell are preferably bonded through an appropriate pressure-sensitive adhesive layer. As a driving method of the liquid crystal cell, for example, an arbitrary type of thing such as a VA mode, an IPS mode, a TN mode, an STN mode, and a bend orientation (pi type) can be used.

As an organic electroluminescent cell, the thing etc. which laminated|stacked a transparent electrode, an organic light-emitting layer, and a metal electrode sequentially on a transparent substrate, and formed the light-emitting body (organic electroluminescent light-emitting body) are used suitably. The organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer containing a triphenylamine derivative and a light emitting layer containing a fluorescent organic solid such as anthracene, or an electron containing these light emitting layers and a perylene derivative, etc. Various layer configurations, such as a laminate of injection layers, or a laminate of a hole injection layer, a light emitting layer, and an electron injection layer, may be employed.

<Bonding of image display cell and polarizing plate>

An adhesive layer (adhesive sheet) is used suitably for bonding of an image display cell and a polarizing plate. Especially, the method of bonding an image display cell and the polarizing plate with an adhesive layer by which the adhesive layer was laid on one side of a polarizing plate from a viewpoint of workability|operativity etc. is preferable. Laying of the pressure-sensitive adhesive layer to the polarizing plate can be performed in an appropriate manner. As an example, about 10 to 40 mass % of an adhesive solution obtained by dissolving or dispersing a base polymer or its composition in a solvent consisting of a single substance or a mixture of an appropriate solvent such as toluene or ethyl acetate is prepared, and it is used in a casting method or A method of directly laying on a polarizing plate by an appropriate development method, such as a coating method, or a method of forming an adhesive layer on a separator and transferring it to a polarizing plate, etc. are mentioned.

<Adhesive layer>

The pressure-sensitive adhesive layer may include one layer or may include two or more layers, but preferably includes one layer. The pressure-sensitive adhesive layer can be composed of a pressure-sensitive adhesive composition containing (meth)acrylic resins, rubber-based resins, urethane-based resins, ester-based resins, silicone-based resins, and polyvinyl ether-based resins as main components. Among them, a pressure-sensitive adhesive composition using a (meth)acrylic resin excellent in transparency, weather resistance, heat resistance, etc. as a base polymer is suitable. An active energy ray hardening type or a thermosetting type may be sufficient as an adhesive composition.

As the (meth)acrylic resin (base polymer) used in the pressure-sensitive adhesive composition, (meth)acrylic acid esters such as (meth)butyl acrylate, (meth)ethyl acrylate, (meth)acrylate isooctyl, (meth)acrylic acid 2-ethylhexyl Polymers or copolymers containing one or two or more of them as a monomer are preferably used. It is preferable to copolymerize a polar monomer with a base polymer. As the polar monomer, (meth)acrylic acid compound, (meth)acrylic acid 2-hydroxypropyl compound, (meth)acrylic acid hydroxyethyl compound, (meth)acrylamide compound, N,N-dimethylaminoethyl (meth)acrylate compound and monomers having a carboxyl group, a hydroxyl group, an amide group, an amino group, an epoxy group, and the like, such as a glycidyl (meth)acrylate compound.

The pressure-sensitive adhesive composition may contain only the base polymer, but usually further contains a crosslinking agent. Examples of the crosslinking agent include a metal ion having a divalent or higher valence, which forms a carboxylate metal salt between a carboxyl group, a polyamine compound that forms an amide bond between a carboxyl group, and a polyepoxy that forms an ester bond between a carboxyl group A polyisocyanate compound which forms an amide bond between a compound or a polyol, and a carboxyl group is illustrated. Especially, a polyisocyanate compound is preferable.

The active energy ray-curable pressure-sensitive adhesive composition has a property of being cured by irradiation with active energy rays such as ultraviolet rays or electron beams, has adhesiveness even before active energy ray irradiation, and can be adhered to an adherend such as a film, and can be irradiated with active energy rays It has the property of being able to adjust the adhesion by curing it. It is preferable that an active energy ray hardening-type adhesive composition is an ultraviolet curable type. The active energy ray-curable pressure-sensitive adhesive composition further contains an active energy ray-polymerizable compound in addition to the base polymer and the crosslinking agent. You may make it contain a photoinitiator, a photosensitizer, etc. as needed.

The pressure-sensitive adhesive composition includes fine particles for imparting light scattering properties, beads (resin beads, glass beads, etc.), glass fibers, resins other than the base polymer, tackifiers, fillers (metal powders and other inorganic powders, etc.), antioxidants, Additives such as ultraviolet absorbers, dyes, pigments, colorants, defoamers, corrosion inhibitors, and photoinitiators may be included.

An adhesive layer can be formed by apply|coating the organic solvent dilution liquid of the said adhesive composition on the surface of a base film, an image display cell, or a polarizing plate, and drying it. It is common that a base film is a thermoplastic resin film, and the separator film to which the mold release process was given is mentioned as the typical example. The separator film, for example, may be a film made of a resin such as polyethylene terephthalate, polybutylene terephthalate, polycarbonate, or polyalate that has been subjected to a release treatment such as silicone treatment on the surface on which the pressure-sensitive adhesive layer is formed.

For example, the pressure-sensitive adhesive composition may be directly applied to the release-treated surface of the separate film to form a pressure-sensitive adhesive layer to form a pressure-sensitive adhesive layer, and this pressure-sensitive adhesive layer with a separate film may be laminated on the surface of the polarizer. A pressure-sensitive adhesive composition may be directly applied to the surface of the polarizing plate to form an adhesive layer, and a separate film may be laminated on the outer surface of the pressure-sensitive adhesive layer.

When the pressure-sensitive adhesive layer is formed on the surface of the polarizing plate, the surface to be bonded of the polarizing plate and/or the surface to be bonded of the pressure-sensitive adhesive layer is preferably subjected to a surface activation treatment, such as plasma treatment, corona treatment, etc., more preferably.

Further, a pressure-sensitive adhesive composition is applied on the second separate film to form a pressure-sensitive adhesive layer, a pressure-sensitive adhesive sheet in which a separate film is laminated on the formed pressure-sensitive adhesive layer is prepared, and the second separate film is peeled from the pressure-sensitive adhesive sheet. You may laminate|stack the provided adhesive layer on a polarizing plate. As for the 2nd separate film, the adhesive force with an adhesive layer is weaker than a separate film, and the thing which peels easily is used.

Although the thickness of an adhesive layer is not specifically limited, For example, it is preferable that they are 1 micrometer or more and 100 micrometers or less, It is more preferable that they are 3 micrometers or more and 50 micrometers or less, 20 micrometers or more may be sufficient.

<No transparency>

As a transparent member arrange|positioned on the visual recognition side of an image display apparatus, a front board (window layer), a touch panel, etc. are mentioned. As the face plate, a face plate having an appropriate mechanical strength and thickness is used. Examples of such a front plate include a transparent resin plate or a glass plate such as polyimide-based resin, acrylic resin, or polycarbonate-based resin. Functional layers, such as an antireflection layer, may be laminated|stacked on the visual recognition side of a front plate. In addition, when a front plate is a transparent resin board, in order to raise a physical strength, in order to make a hard-coat layer and a water vapor transmission rate lower, you may laminate|stack the low moisture-permeable layer.

As a touch panel, various touch panels, such as a resistive film system, a capacitive system, an optical system, an ultrasonic system, a glass plate, a transparent resin plate, etc. provided with a touch sensor function are used. When a capacitive touch panel is used as the transparent member, it is preferable that a front plate made of glass or a transparent resin plate is provided further on the visual recognition side than the touch panel.

<Joining of polarizing plate and transparent member>

An adhesive or an active energy ray hardening-type adhesive agent is used suitably for bonding of a polarizing plate and a transparent member. When a pressure-sensitive adhesive is used, the laying of the pressure-sensitive adhesive can be obtained by performing in an appropriate manner. As a specific laying method, the laying method of the adhesive layer used by bonding of the image display cell and polarizing plate mentioned above, for example is mentioned.

When an active energy ray-curable adhesive is used, a dam material is provided to surround the periphery on the image display panel for the purpose of preventing the adhesive solution from spreading before curing, and a transparent member is disposed on the dam material to inject the adhesive solution method is suitably used. After injection of the adhesive solution, alignment and defoaming are performed if necessary, and then, active energy rays are irradiated to cure.

Example

Hereinafter, the present invention will be specifically described based on Examples. Materials, reagents, amounts of substances, ratios, operations, and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Therefore, the present invention is not limited to the following examples.

(1) Measurement of thickness of polarizer:

Measurements were made using a digital micrometer “MH-15M” manufactured by Nikon Corporation.

(2) Measurement of transmittance of a polarizing element corrected for visibility:

Spectrophotometer with integrating sphere ["V7100" manufactured by Nippon Bunko Co., Ltd., 2 degree field of view; C light source].

(3) Measurement of boron content of polarizing element:

0.2 g of the polarizing element was dissolved in 200 g of a 1.9 mass% mannitol aqueous solution. Next, the obtained aqueous solution was titrated with 1 mol/L sodium hydroxide aqueous solution, and the boron content rate of the polarizing element was computed by comparison with the quantity of the sodium hydroxide aqueous solution required for neutralization, and a calibration curve.

(4) Measurement of yellow index (yellowness):

A spectrophotometer CM-3700A manufactured by Konica Minolta was used.

(5) Measurement of boron adsorption rate of PVA-based resin film:

The PVA-based resin film cut into 100 mm square was immersed in 30°C pure water for 60 seconds, and then immersed in a 60°C aqueous solution containing 5 parts of boric acid for 120 seconds. The PVA-based resin film taken out from the aqueous boric acid solution was dried in an oven at 80°C for 11 minutes. Humidity was controlled in an environment of 23°C and 55% %RH for 24 hours to obtain a boron-containing PVA film. 0.2 g of the thus-obtained boron-containing PVA-based resin film was dissolved in 200 g of an aqueous solution of 1.9% by mass of mannitol. Next, the obtained aqueous solution was titrated with 1 mol/L sodium hydroxide aqueous solution, and the boron content rate of the PVA-type resin film was computed by comparison with the quantity of the sodium hydroxide aqueous solution required for neutralization, and a calibration curve. The boron content rate of the PVA system resin film obtained in this way was used as the boron adsorption rate of the PVA system resin film.

(Production of Polarizing Element 1)

After immersing a 45 μm thick polyvinyl alcohol-based resin film having a boron adsorption rate of 5.90 mass% in pure water at 21.5° C. for 79 seconds, the weight ratio of potassium iodide/boric acid/water is 2/2/100 and containing 1.0 mM iodine It was immersed in aqueous solution at 23 degreeC for 151 second. Then, it immersed in the aqueous solution whose weight ratio of potassium iodide/boric acid/water is 2.5/4/100 at 60.8 degreeC for 76 seconds. Then, it immersed in the aqueous solution whose weight ratio of potassium iodide / boric acid / water is 3/5.5/100 at 45 degreeC for 11 second. Then, it dried at 38 degreeC, and obtained the 18-micrometer-thick polarizing element by which iodine was adsorbed and oriented to polyvinyl alcohol. Stretching was mainly performed in iodine dyeing and boric acid treatment steps, and the total draw ratio was 5.85 times. The obtained polarizing element had a transmittance of 41.07% and a boron content of 4.84% by mass of the luminous sensitivity corrected monolithic transmittance.

(Production of Polarizing Element 2)

After immersing a 45 µm-thick polyvinyl alcohol-based resin film having a boron adsorption rate of 5.73 mass% in pure water at 21.5° C. for 79 seconds, the weight ratio of potassium iodide/boric acid/water is 2/2/100 and containing 1.0 mM iodine. It was immersed in aqueous solution at 23 degreeC for 151 second. Then, it immersed in the aqueous solution whose weight ratio of potassium iodide/boric acid/water is 2.5/4/100 at 60.8 degreeC for 76 seconds. Then, it immersed in the aqueous solution whose weight ratio of potassium iodide / boric acid / water is 3/5.5/100 at 45 degreeC for 11 second. Then, it dried at 38 degreeC, and obtained the 18-micrometer-thick polarizing element by which iodine was adsorbed and oriented to polyvinyl alcohol. Stretching was mainly performed in iodine dyeing and boric acid treatment steps, and the total draw ratio was 5.85 times. The obtained polarizing element had a transmittance of 41.06% and a boron content of 4.62% by mass for the luminous sensitivity corrected monolithic transmittance.

(Production of Polarizing Element 3)

After immersing a 45 μm thick polyvinyl alcohol-based resin film having a boron adsorption rate of 5.71 mass % in pure water at 21.5° C. for 79 seconds, the weight ratio of potassium iodide/boric acid/water is 2/2/100 and containing 1.0 mM iodine. It was immersed in aqueous solution at 23 degreeC for 151 second. Then, it was immersed at 60.8 degreeC for 76 second in the aqueous solution whose weight ratio of potassium iodide/boric acid/water is 2.5/4/10. Then, it immersed in the aqueous solution whose weight ratio of potassium iodide / boric acid / water is 3/5.5/100 at 45 degreeC for 11 second. Then, it dried at 38 degreeC, and obtained the 18-micrometer-thick polarizing element by which iodine was adsorbed and oriented to polyvinyl alcohol. Stretching was mainly performed in iodine dyeing and boric acid treatment steps, and the total draw ratio was 5.85 times. The obtained polarizing element had a transmittance of 40.96% and a boron content of 4.48% by mass, as corrected for visibility.

(Production of Polarizing Element 4)

After immersing a 45 μm thick polyvinyl alcohol-based resin film having a boron adsorption rate of 5.68 mass% in pure water at 21.5° C. for 79 seconds, the weight ratio of potassium iodide/boric acid/water is 2/2/100 and containing 1.0 mM iodine It was immersed in aqueous solution at 23 degreeC for 151 second. Then, it immersed in the aqueous solution whose weight ratio of potassium iodide/boric acid/water is 2.5/4/100 at 60.8 degreeC for 76 seconds. Then, it immersed in the aqueous solution whose weight ratio of potassium iodide / boric acid / water is 3/5.5/100 at 45 degreeC for 11 second. Then, it dried at 38 degreeC, and obtained the 18-micrometer-thick polarizing element by which iodine was adsorbed and oriented to polyvinyl alcohol. Stretching was mainly performed in iodine dyeing and boric acid treatment steps, and the total draw ratio was 5.85 times. The obtained polarizing element had a transmittance of 40.88% and a boron content of 4.35% by mass of the luminous sensitivity corrected monolithic transmittance.

(Preparation of PVA solution for adhesive)

50 g of a modified PVA-based resin containing an acetoacetyl group (manufactured by Mitsubishi Chemical Co., Ltd.: Gosenex Z-410) was dissolved in 950 g of pure water, heated at 90° C. for 2 hours, cooled to room temperature, and PVA solution for adhesive got

(Preparation of adhesive 1 for polarizing plate)

The prepared PVA solution for adhesives, pure water, and methanol were mix|blended so that it might become PVA concentration 3.0%, methanol concentration 35%, and urea concentration 0.5%, and the adhesive agent 1 for polarizing plates was obtained.

(Preparation of adhesive 2 for polarizing plate)

The prepared PVA solution for adhesives, pure water, and methanol were mix|blended so that it might become PVA concentration 3.0%, methanol concentration 5%, and urea concentration 0.5%, and the adhesive agent 2 for polarizing plates was obtained.

(Saponification of cellulose acylate film)

A commercially available cellulose acylate film KC4UYW (manufactured by Konica Minolta Co., Ltd.: film thickness of 40 μm) was immersed in 1.5 mol/L NaOH aqueous solution (saponification solution) maintained at 55° C. for 2 minutes, and then the film was washed with water, Then, after being immersed in 25 degreeC 0.05 mol/L sulfuric acid aqueous solution for 30 seconds, a water washing bath was further passed under running water for 30 seconds, and the film was made into a neutral state. And after repeating dehydration with an air knife 3 times and dripping water, it was made to stay for 15 second in a 70 degreeC drying zone, and it dried, and produced the saponification process film.

(Production of Polarizer 1)

On both sides of the polarizing element 1, the saponification-treated cellulose acylate film prepared above was adjusted through the polarizing plate adhesive 1 so that the thickness of the adhesive layer after drying was 100 nm on both sides, and after bonding using a roll bonding machine, 80 ° C. was dried for 3 minutes to obtain a polarizing plate 1 with a double-sided cellulose acylate film.

(Production of Polarizer 2)

Except having changed the polarizing element 1 of the polarizing plate 1 into the polarizing element 2, it carried out similarly to preparation of the polarizing plate 1, and produced the polarizing plate 2.

(Production of Polarizer 3)

Except having changed the polarizing element 1 of the polarizing plate 1 to the polarizing element 3, it carried out similarly to preparation of the polarizing plate 1, and produced the polarizing plate 3.

(Production of Polarizer 4)

Except having changed the adhesive agent 1 for polarizing plates of the polarizing plate 3 into the adhesive agent 2 for polarizing plates, it carried out similarly to preparation of the polarizing plate 3, and produced the polarizing plate 4.

(Production of Polarizer 5)

Except having changed the adhesive agent 1 for polarizing plates of the polarizing plate 2 into the adhesive agent 2 for polarizing plates, it carried out similarly to preparation of the polarizing plate 2, and produced the polarizing plate 5.

(Production of Polarizer 6)

Except having changed the polarizing element 1 of the polarizing plate 1 to the polarizing element 4, it carried out similarly to preparation of the polarizing plate 1, and produced the polarizing plate 6.

(Production of optical laminate 1)

By applying an acrylic pressure-sensitive adhesive (manufacturer: Lintech Co., Ltd.) to both sides of the polarizing plate 1 prepared above with reference to the examples of Japanese Patent Application Laid-Open No. 2018-025765, an optical having a pressure-sensitive adhesive layer having a thickness of 25 μm on both sides Laminate 1 was produced.

(Production of optical laminates 2 to 6)

Except having changed the polarizing plate 1 into the polarizing plates 2-6, it carried out similarly to preparation of the optical laminated body 1, and produced the optical laminated bodies 2-6.

[High temperature endurance test (105 ° C)]

An evaluation sample was produced by cutting the optical laminates 1 to 6 produced above to a size of 50 mm x 100 mm, respectively, and bonding the surfaces of each adhesive layer on both sides to alkali-free glass [trade name "EAGLEXG", manufactured by Corning Corporation]. . In addition, when producing these samples, in order to adjust the moisture content of a polarizing element before bonding to a glass plate, the optical laminated body was stored in the environment of the temperature of 20 degreeC and 40% of relative humidity for 72 hours. In addition, all samples were measured for mass at 66 hours, 69 hours, and 72 hours after storage, but there was no change. Accordingly, it can be considered that the moisture content of the optical laminates 1 to 6 is equal to the equilibrium moisture content of the storage environment for 72 hours used in the present experimental example. When the moisture content of the optical laminate reaches equilibrium in a certain storage environment, it can be considered that the moisture content of the polarizing plate in the optical laminate and the moisture content of the polarizing element in the polarizing plate have reached equilibrium in the storage environment as well. In addition, when the moisture content of the polarizing element in the polarizing plate reached equilibrium in a certain storage environment, it can be considered that the moisture content of the polarizing plate also reached equilibrium in the storage environment.

After autoclaving this evaluation sample at the temperature of 50 degreeC and the pressure of 5 kgf/cm<2> (490.3 kPa) for 1 hour, it was left to stand in the environment of the temperature of 23 degreeC and 55% of relative humidity for 24 hours. Then, the transmittance|permeability was measured (initial value), it stored in the high temperature environment with a temperature of 105 degreeC, and the yellow index after 168 hours was measured. The yellow index was measured using the value of the reflection color when the evaluation sample was placed on a mirror surface and light was incident on it. Tables 1 and 2 show the measured values of the yellow index.

Since the optical laminated bodies 1-5 have a yellow index of 50 or less, even if it stores in a high-temperature environment, it turns out that the fall of the transmittance|permeability is suppressed.

Claims (15)

A polarizing plate comprising a polarizing element formed by adsorbing and aligning a dichroic dye to a polyvinyl alcohol-based resin layer and a transparent protective film,
The polyvinyl alcohol-based resin used to form the polyvinyl alcohol-based resin layer has a boron adsorption rate of 5.70 mass% or more,
A polarizing plate in which the moisture content of the polarizing element is equal to or greater than an equilibrium moisture content at a temperature of 20°C and a relative humidity of 30% and equal to or less than an equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%. A polarizing plate comprising a polarizing element formed by adsorbing and aligning a dichroic dye to a polyvinyl alcohol-based resin layer and a transparent protective film,
The polyvinyl alcohol-based resin used to form the polyvinyl alcohol-based resin layer has a boron adsorption rate of 5.70 mass% or more,
A polarizing plate in which the moisture content of the polarizing plate is equal to or greater than an equilibrium moisture content of 30% relative humidity at a temperature of 20°C and less than or equal to an equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%. The polarizing plate according to claim 1 or 2, wherein the polarizing element has a boron content of 4.0 mass% or more and 8.0 mass%. The method according to any one of claims 1 to 3, further comprising an adhesive layer for bonding the polarizing element and the transparent protective film;
The adhesive layer is a polarizing plate that is a coating layer of a water-based adhesive. The polarizing plate according to claim 4, wherein the water-based adhesive has a methanol concentration of 10% by mass or more and 70% by mass or less. The polarizing plate according to claim 4 or 5, wherein the water-based adhesive includes a polyvinyl alcohol-based resin. The polarizing plate according to any one of claims 4 to 6, wherein the adhesive layer has a thickness of 0.01 µm or more and 7 µm or less. The method according to any one of claims 1 to 7, wherein the transparent protective film is a retardation film including a first optical compensation layer and a second optical compensation layer sequentially from the polarizing element side,
an absorption axis of the polarizing element and a slow axis of the first optical compensation layer are substantially orthogonal to each other;
The slow axis of the first optical compensation layer and the slow axis of the second optical compensation layer are approximately parallel;
The first optical compensation layer and the second optical compensation layer is a polarizing plate that satisfies the following formulas (1) to (4):
80 nm≤Re ₁ (590)≤120 nm (1)
20 nm<Re ₁ (590)≤60 nm (2)
1<Nz ₁ <2 (3)
-4<Nz ₂ <-1 (4) The method according to any one of claims 1 to 8, wherein the polarizing plate is used in an image display device,
A polarizing plate in which a solid layer is formed in contact with both surfaces of the polarizing plate in the image display device. The image display cell, the 1st adhesive layer laminated|stacked on the surface of the visual recognition side of the said image display cell, and Claims 1-9 laminated|stacked on the visual recognition side surface of the said 1st adhesive layer. An image display device having a polarizing plate. The image display device according to claim 10, further comprising: a second pressure-sensitive adhesive layer laminated on the surface of the polarizing plate on the viewer side; and a transparent member stacked on the surface of the second pressure-sensitive adhesive layer on the viewer side. The image display apparatus according to claim 11, wherein the transparent member is a glass plate or a transparent resin plate. The image display apparatus according to claim 11, wherein the transparent member is a touch panel. A method for manufacturing the polarizing plate according to claim 1, comprising:
A method for manufacturing a polarizing plate having a polarizing element and a transparent protective film,
a moisture content adjustment step of adjusting the moisture content of the polarizing element to be equal to or higher than the equilibrium moisture content of 30% relative humidity at a temperature of 20°C and less than or equal to the equilibrium moisture content at a temperature of 20°C and a relative humidity of 50%;
Lamination process of laminating the polarizing element and the transparent protective film
A method of manufacturing a polarizing plate having A method for producing the polarizing plate according to claim 2, comprising:
A method for manufacturing a polarizing plate having a polarizing element and a transparent protective film,
A moisture content adjustment step of adjusting the moisture content of the polarizing plate to be equal to or greater than the equilibrium moisture content of 30% relative humidity at a temperature of 20° C. and less than or equal to the equilibrium moisture content at a temperature of 20° C. of 50% relative humidity;
Lamination process of laminating the polarizing element and the transparent protective film
A method of manufacturing a polarizing plate having