JP2015215605A - Polarizing plate and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing plate that can suppress cracks in the polarizing plate in a heat cycle environment, peeling at an end of an image display device in a high-temperature environment where changes in the temperature and humidity are repeated, and uneven brightness of an image display device in an environment where humidity greatly varies.SOLUTION: The polarizing plate includes a second film, a first film, and an adhesive layer in this order, in which the direction of an absorption axis of the first film is parallel to the direction where an elastic modulus of the second film is maximum; and values X and Y described below are 135 or less and 0.30 or less, respectively. X and Y are defined by: X=E×d×ε+E×d×ε; and Y=(σ+σ⊥)/{(E+E⊥)×d}; where σ={E×d×|ε-ε|}, ε=(E×d×ε+E×d×ε)/(E×d+E×d), σ⊥={E⊥×d×|ε⊥-ε⊥|}, and ε⊥=(E⊥×d×ε⊥+E⊥×d×ε⊥)/(E⊥×d+E⊥×d).

Description

  The present invention relates to a polarizing plate and an image display device. More specifically, polarizing plate cracking in an environment in which high-temperature and low-temperature heat cycles are repeated is suppressed, and the edge of the polarizing plate in an environment in which temperature and humidity changes at high temperatures are repeated when incorporated in an image display device The present invention relates to a polarizing plate capable of suppressing peeling and capable of suppressing luminance unevenness under an environment where humidity fluctuation is large when incorporated in an image display device, and an image display device including the polarizing plate.

  Polymer films represented by cellulose ester, polyester, polycarbonate, cycloolefin polymer vinyl polymer, polyimide and the like are used for silver halide photographic light-sensitive materials, retardation films, polarizing plates and image display devices. From these polymers, films that are more excellent in terms of flatness and uniformity can be produced, and are therefore widely used as films for optical applications.

  Among these, cellulose acylate films (especially cellulose acetate films) and acrylic films with appropriate moisture permeability can be directly bonded online with the most common polarizers made of polyvinyl alcohol (PVA) / iodine. It is. Therefore, it is widely adopted as a protective film for polarizing plates.

  Since the polarizing plate expands and contracts with changes in the environment, for example, in an image display device that uses a polarizing plate that absorbs moisture during storage and transportation, the water present in the polarizing plate evaporates due to the heat generated when the backlight is turned on. It is known that warpage occurs in a plate or a liquid crystal panel. When slimming and enlargement are promoted, failures such as uneven brightness may occur in the periphery of the screen display device due to warpage of the polarizing plate or the liquid crystal panel. Patent Document 1 discloses a method for improving the warpage of an image display device that is a liquid crystal panel under a high-temperature and high-humidity environment by adjusting the dimensional change rate of a polarizing plate. A method for improving the warp of an image display device in a high-temperature and high-humidity environment by adjusting the creep characteristics of an adhesive layer formed on a polarizing plate is disclosed. On the other hand, Patent Document 3 discloses a method for improving the warpage of an image display device in a high temperature environment by thinning a polarizer. Patent Document 4 describes a method of adjusting a modulus of elasticity and a humidity expansion coefficient by stretching a transparent polymer film.

In Patent Document 5, the shrinkage force difference Fw (unit × 10 N / m) after wet heat treatment represented by the following formulas (1) to (3) is in the range of 1 to 34, and the following formulas (4) to (6) ), And the in-plane retardation (Re) measured at a wavelength of 590 nm is less than 10 nm, and at a wavelength of 590 nm. A liquid crystal panel using a retardation film or a polarizing plate manufactured using an optical film having an absolute value of measured thickness direction retardation (Rth) of less than 25 nm, and a liquid crystal display device are used in a high-temperature and high-humidity environment or a high-temperature environment. It is described that the occurrence of uneven brightness is improved and shows excellent reliability.
[Wet heat treatment means treatment for holding the film for 48 hours in an environment of 60 ° C. and 90% relative humidity, and heat treatment means treatment for 48 hours in an environment of 80 ° C. The direction of maximum propagation speed of sound waves is the maximum direction of propagation speed of longitudinal vibration of ultrasonic pulses after the film is conditioned for 24 hours at 25 ° C. and 60% relative humidity. ]
Formula (1) Fw = Fw1-Fw2
[In the formula, Fw1 is the contraction force of the optical film after the wet heat treatment in the direction where the sound wave propagation speed is maximum, and Fw2 is the contraction force after the heat treatment in the direction orthogonal to the maximum direction of sound wave propagation. ]
Formula (2) Fw1 = Ew1 × εw1 × dw
[In the formula, all characteristic quantities are values in which the sound wave propagation speed is in the maximum direction. Ew1 is the elastic modulus after the wet heat treatment, εw1 is the absolute value of the humidity dimensional change rate after the wet heat treatment, and dw is the film thickness after the wet heat treatment. Ew1 is in the range of 2.0 to 8.0 GPa, εw1 is in the range of 0.01 to 0.38%, and dw is in the range of 5 to 80 μm. ]
Formula (3) Fw2 = Ew2 × εw2 × dw
[In the formula, all the characteristic quantities are values in a direction in which the sound wave propagation velocity is orthogonal to the maximum direction. Ew2 is the elastic modulus, εw2 is the absolute value of the rate of change in humidity after wet heat treatment, and dw is the film thickness. Ew2 is in the range of 1.0 to 5.0 GPa, εw2 is in the range of 0.13 to 0.50%, and dw is in the range of 5 to 80 μm. ]
Formula (4) Fd = Fd1−0.1 × Fd2
[In the formula, Fd1 is the contraction force after heat treatment in the direction where the sound wave propagation speed is the maximum, and Fd2 is the contraction force after heat treatment in the direction where the sound wave propagation speed is orthogonal to the maximum direction. ]
Formula (5) Fd1 = Ed1 × εd1 × dd
[In the formula, all characteristic quantities are values in which the sound wave propagation speed is in the maximum direction. Ed1 is the elastic modulus, εd1 is the absolute value of the dimensional change rate, and dd is the film thickness. Ed1 is 2.5 to 10.0 GPa, εd1 is 0.01 to 1.00%, and dd is 5 to 80 μm. ]
Formula (6) Fd2 = Ed2 × εd2 × dd
[In the formula, all the characteristic quantities are values in a direction in which the sound wave propagation velocity is orthogonal to the maximum direction. Ed2 (unit GPa) is an elastic modulus, εd2 is an absolute value of a dimensional change rate, and dd is a film thickness. Ed2 is 1.5 to 5.5 GPa, εd2 is 0.01 to 1.00%, and dd is 5 to 80 μm. ]

Patent Document 6 includes a compound having a repeating unit and a compound containing at least a cellulose ester, an in-plane retardation (Re) at a wavelength of 590 nm of 10 nm or less, an elastic modulus exceeding 3.5 GPa, and a compound having a repeating unit. An optical film, a roll-shaped optical film, which is a condensate of a basic acid and a polyhydric alcohol, and which suppresses shrinkage and improves the elastic modulus by an optical film that satisfies the following conditions (1) to (6) It is described that a polarizing plate and a liquid crystal display device can be provided.
(1) At least a polybasic acid having 5 or less carbon atoms is included as the polybasic acid.
(2) The average carbon number of the polybasic acid is 3 or more and less than 6.
(3) The average carbon number of the polyhydric alcohol is 2 or more and 3 or less.
(4) All repeating units composed of a combination of one kind of polybasic acid and one kind of polyhydric alcohol have 4 to 9 carbon atoms.
(5) Number average molecular weight is 800 or more and 5000 or less.
(6) The hydroxyl value is less than 40 mgKOH / g.

JP 2007-292966 A JP 2003-50313 A JP 2012-13764 A JP 2007-331388 A JP 2014-95880 A JP 2014-164169 A

  Conventionally, a polarizing plate has been designed on the assumption that a polarizer used for a polarizing plate of an image display device has a film thickness of about 30 μm and a protective film has a film thickness of 40 μm or more and sufficient mechanical strength. In particular, polarizers are said to have high rigidity, and until now, the shrinkage force caused by the dimensional change of the polarizer accompanying the environmental change is the main cause of the warp of the image display device under the environment where the environment changes greatly. It has been thought that there is.

However, with the recent thinning of image display devices and polarizing plates used therefor, the film thickness of the polarizer and the protective film has been reduced, and the premise that the polarizer and the protective film have sufficient mechanical strength has collapsed. Yes. When such thin polarizers and protective films that do not have sufficient mechanical strength are used, the methods described in Patent Documents 1 to 6 cause various problems caused by warping of the image display device under an environment where the environment changes greatly. For example, it has been found that problems of polarizing plate cracking, end peeling of the polarizing plate, and luminance unevenness occur. In particular, when the present inventors examined, even in the methods described in Patent Documents 1 to 6, in an environment in which a change in temperature from a low temperature lower than 0 ° C. to a high temperature higher than 60 ° C. is repeated (hereinafter referred to as “high temperature and low temperature”). "In an environment where the heat cycle is repeated" is defined as an environment in which the temperature changes from a low temperature lower than 0 ° C to a high temperature higher than 60 ° C). In an environment where a temperature change of 5 ° C. or more and a relative humidity change of 60% or more are repeated at a high temperature above (hereinafter “an environment where temperature and humidity changes are repeated at a high temperature”), It is defined as an environment in which the above temperature change and relative humidity change of 60% or more are repeated), and the end of the polarizing plate is peeled off, or the image display device is left in the high humidity environment for a long time. Equipment When the lamp is lit in an environment where the degree of fluctuation is large (for example, after the image display device is held for 14 days in an environment of 45 ° C. and a relative humidity of 80%, the image display device is moved to an environment of 25 ° C. and a relative humidity of 60%. It was revealed that brightness unevenness occurred when the lamp was lit for a long time. In particular, when using an image display device stored at a low temperature below 0 ° C. in a cold region, the polarizing plate when the backlight is turned on becomes a high temperature exceeding 60 ° C., and after being turned off, it is stored again at a low temperature below 0 ° C. When the actual user uses the image display device, the backlight is repeatedly turned on and off. By repeatedly turning on and off the backlight, the polarizing plate is exposed to a high-temperature and low-temperature heat cycle environment. Alternatively, when an actual user uses the image display device for a long time in an environment where the temperature and humidity change during the day is high, the temperature and humidity change is repeated at a high temperature due to the heat of the backlight that remains lit. With this long use, the liquid crystal panel is exposed to an environment where temperature and humidity changes are repeated at high temperatures. Patent Documents 5 and 6 only examine the initial state and the case where the image display device is exposed to an environment in which the temperature and humidity have changed only once. Did not pay attention to the performance in the environment where is repeated.
Therefore, without assuming that the polarizer and protective film used for the polarizing plate of the image display device are thick and have sufficient mechanical strength, regardless of the thickness of the polarizer and protective film and the magnitude of the mechanical strength. In addition, it has been demanded to investigate a new polarizing plate design method capable of suppressing the occurrence of various problems caused by warping of the image display device under a changing environment.

  It has been found that not only the polarizing plate warps but also the polarizing plate cracks in an environment where high and low temperature heat cycles are repeated. The problem to be solved by the present invention is that when incorporated in an image display device, it is possible to suppress end peeling of the polarizing plate in an environment where temperature and humidity changes are repeated at high temperatures. An object of the present invention is to provide a polarizing plate capable of suppressing luminance unevenness under a large environment and suppressing cracking of the polarizing plate under an environment where high and low temperature heat cycles are repeated.

As a result of diligent investigations by the present inventors, in recent polarizing plates in which the polarizer has become thinner and the contraction force of the polarizer has decreased, the contraction force that causes the warp of the image display device as in the past has been reduced. It has been found that it is essential to introduce not only the shrinkage force of the polarizer but also the contribution rate of the shrinkage force of the protective film into the design of the polarizing plate.
In addition, the internal stress generated in the polarizer due to the difference in humidity dimensional change between the polarizer and the polarizing plate is applied to the rigidity of the polarizing plate protective film (if the polarizing plate has a polarizing plate protective film on both sides, the polarizing plate is protected. By reducing the value (value Y or value y described later) divided by the sum of the rigidity of the film, the polarizing plate cracks in an environment where high and low temperature heat cycles are repeated, and the temperature and humidity change at high temperatures. It has been found that the peeling of the edge of the polarizing plate of the image display device can be stably suppressed in an environment where the above is repeated.
Further, by reducing the sum of the contraction force of the polarizer and the contraction force of the polarizing plate protective film in the direction parallel to the absorption axis of the polarizer (value X or value x described later), it is mainly in a high humidity environment. In addition, it has been found that luminance unevenness that occurs when the image display device is lighted in an environment with a large humidity fluctuation after the image display device is left for a long time can be stably suppressed.
From the above, it was found that by simultaneously reducing these values, a polarizing plate capable of solving the above problems can be provided, and the present invention has been completed.

The present invention, which is a specific means for solving the above problems, and preferred embodiments of the present invention are as follows.
[1] Having a second film, a first film and an adhesive layer in this order,
The first film and the adhesive layer are in direct contact,
The first film is a polarizer,
The absorption axis direction of the first film and the direction in which the elastic modulus of the second film is maximum are parallel,
The value X calculated from the following formula (1) is 135 or less,
A polarizing plate having a value Y calculated from the following formula (2) of 0.30 or less;
Expression (1): X = E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //}
Formula (2): Y = (σ _// + σ⊥) / {(E _{2 //} + E ₂ ⊥) × d ₂ }
Formula (2A-1): σ _// = {E _{1 //} × d ₁ × | ε _{p // −} ε _{1 //} |}
Formula (2A-2): ε _{p //} = (E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} ) / (E _{1 //} × d ₁ + E _{2 / /} × d ₂₎
Formula (2B-1): σ⊥ = {E ₁ ⊥ × d ₁ × | ε _p ⊥−ε ₁ ⊥ |}
Formula (2B-2): ε _p ⊥ = (E ₁ ⊥ × d ₁ × ε ₁ ⊥ + E ₂ ⊥ × d ₂ × ε ₂ ⊥) / (E ₁ ⊥ × d ₁ + E ₂ ⊥ × d ₂ )
Where
E _{1 //} represents the elastic modulus of the first film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₁表 し represents the elastic modulus of the first film in the direction orthogonal to the absorption axis direction of the first film, and its unit is GPa;
d ₁ represents the thickness of the first film, the unit is μm;
ε _{1 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the first film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Expresses the rate;
ε ₁ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the first film in the direction orthogonal to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents;
E _{2 //} represents the elastic modulus of the second film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₂ ⊥ represents the elastic modulus of the second film in the direction perpendicular to the absorption axis direction of the first film, and its unit is GPa;
d ₂ represents the thickness of the second film, the unit is μm;
ε _{2 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the second film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Expresses the rate;
ε ₂ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the second film in the direction orthogonal to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents.
[2] Having the second film, the first film, and the third film in this order,
The first film is a polarizer,
The absorption axis direction of the first film and the direction in which the elastic modulus of the second film is maximum are parallel,
The absorption axis direction of the first film and the direction in which the elastic modulus of the third film is maximum are parallel,
The value x calculated from the following formula (3) is 135 or less,
A polarizing plate having a value y calculated from the following formula (4) of 0.30 or less;
Equation (3): x = E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} + E _{3 //} × d ₃ × ε _{3 //}
Formula (4): y = (σ _// + σ⊥) / {(E _{2 //} + E ₂ ⊥) × d ₂ + (E _{3 //} + E ₃ ⊥) × d ₃ }
Formula (4A-1): σ _// = {E _{1 //} × d ₁ × | ε _{p // −} ε _{1 //} |}
Formula (4A-2): ε _{p //} = (E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} + E _{3 //} × d ₃ × ε _{3 //} ) _{/ (E 1 // × d 1} + E 2 // × d 2 + E 3 // × d 3)
Formula (4B-1): σ⊥ = {(E ₁ ⊥ × d ₁ × | ε _p ⊥−ε ₁ ⊥ |}
Formula (4B-2): ε _p ⊥ = (E ₁ ⊥ × d ₁ × ε ₁ ⊥ + E ₂ ⊥ × d ₂ × ε ₂ ⊥ + E ₃ ⊥ × d ₃ × ε ₃ ⊥) / (E ₁ ⊥ × d ₁ + E ₂ ⊥ x d ₂ + E ₃ ⊥ x d ₃ )
Where
E _{1 //} represents the elastic modulus of the first film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₁表 し represents the elastic modulus of the first film in the direction orthogonal to the absorption axis direction of the first film, and its unit is GPa;
d ₁ represents the thickness of the first film, the unit is μm;
ε _{1 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the first film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Expresses the rate;
ε ₁ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the first film in the direction orthogonal to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents;
E _{2 //} represents the elastic modulus of the second film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₂ ⊥ represents the elastic modulus of the second film in the direction perpendicular to the absorption axis direction of the first film, and its unit is GPa;
d ₂ represents the thickness of the second film, the unit is μm;
ε _{2 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the second film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Expresses the rate;
ε ₂ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the second film in the direction orthogonal to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents.
E _{3 //} represents the elastic modulus of the third film in the direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₃表 し represents the elastic modulus of the third film in the direction orthogonal to the absorption axis direction of the first film, and its unit is GPa;
d ₃ represents the thickness of the third film, the unit is μm;
ε _{3 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the third film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Expresses the rate;
ε ₃ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the third film in the direction orthogonal to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents.
[3] In the polarizing plate according to [2], it is preferable that the film thickness d ₂ of the second film and the film thickness d ₃ of the third film are both 35.0 μm or less.
[4] In the polarizing plate according to [2] or [3], the first film and the third film are preferably in direct contact with each other.
[5] In the polarizing plate according to any one of [1] to [4], the second film and the first film are preferably in direct contact.
[6] In the polarizing plate according to any one of [1] to [5], a value obtained by dividing the elastic modulus E _{2 //} of the second film by the elastic modulus E ₂ of the second film is 1.20. The above is preferable.
[7] In the polarizing plate according to any one of [1] to [5], a value obtained by dividing the elastic modulus E _{2 //} of the second film by the elastic modulus E ₂ of the second film is 1.40. The above is preferable.
[8] In the polarizing plate according to any one of [1] to [7], the elastic modulus E _{2 //} of the second film is preferably 5.5 to 10.0 GPa.
[9] In the polarizing plate according to any one of [1] to [8], the value X calculated from the formula (1) or the value x calculated from the formula (3) is 120 or less. preferable.
[10] In the polarizing plate according to any one of [1] to [9], the value Y calculated from the formula (2) or the value y calculated from the formula (4) is 0.22 or less. It is preferable.
[11] In the polarizing plate according to any one of [1] to [10], an antistatic layer, a cured resin layer, a surface of the second film opposite to the surface on which the first film is laminated, It is preferable to include a functional layer selected from an antireflection layer, an antiglare layer, an optical compensation layer, an alignment layer, and a liquid crystal layer.
[12] In the polarizing plate according to any one of [1] to [11], the second film preferably contains at least cellulose acylate as a polymer.
[13] An image display device comprising the polarizing plate according to any one of [1] to [12].

The following aspects are also included in the present invention.
[101] At least a transparent film (second film) is provided on one surface of a film having a polarization separation function (first film),
Laminate so that the absorption axis direction of the first film and the direction in which the sound wave propagation speed of the second film is maximum are parallel or orthogonal,
A polarizing plate satisfying the following formula (1) and d1 being 25 μm or less, where d1 is the thickness of the first film and d2 is the thickness of the second film.
Formula (1) 0.5 <d2 / d1 <5.0

  According to the present invention, when incorporated in an image display device, it is possible to suppress the end peeling of the polarizing plate in an environment where temperature and humidity changes are repeated at a high temperature. It is possible to provide a polarizing plate capable of suppressing unevenness in brightness and suppressing cracking of the polarizing plate in an environment where high and low temperature heat cycles are repeated.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments. In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

[Polarizer]
The 1st aspect of the polarizing plate of this invention has a 2nd film, a 1st film, and an adhesive material layer in this order,
The first film and the adhesive layer are in direct contact,
The first film is a polarizer,
The absorption axis direction of the first film and the direction in which the elastic modulus of the second film is maximum are parallel,
The value X calculated from the following formula (1) is 135 or less,
The value Y calculated from the following formula (2) is 0.30 or less.
Expression (1): X = E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //}
Formula (2): Y = (σ _// + σ⊥) / {(E _{2 //} + E ₂ ⊥) × d ₂ }
Formula (2A-1): σ _// = {E _{1 //} × d ₁ × | ε _{p // −} ε _{1 //} |}
Formula (2A-2): ε _{p //} = (E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} ) / (E _{1 //} × d ₁ + E _{2 / /} × d ₂₎
Formula (2B-1): σ⊥ = {E ₁ ⊥ × d ₁ × | ε _p ⊥−ε ₁ ⊥ |}
Formula (2B-2): ε _p ⊥ = (E ₁ ⊥ × d ₁ × ε ₁ ⊥ + E ₂ ⊥ × d ₂ × ε ₂ ⊥) / (E ₁ ⊥ × d ₁ + E ₂ ⊥ × d ₂ )
The 2nd aspect of the polarizing plate of this invention has a 2nd film, a 1st film, and a 3rd film in this order,
The first film is a polarizer,
The absorption axis direction of the first film and the direction in which the elastic modulus of the second film is maximum are parallel,
The absorption axis direction of the first film and the direction in which the elastic modulus of the third film is maximum are parallel,
The value x calculated from the following formula (3) is 135 or less,
The value y calculated from the following formula (4) is 0.30 or less.
Equation (3): x = E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} + E _{3 //} × d ₃ × ε _{3 //}
Formula (4): y = (σ _// + σ⊥) / {(E _{2 //} + E ₂ ⊥) × d ₂ + (E _{3 //} + E ₃ ⊥) × d ₃ }
Formula (4A-1): σ _// = {E _{1 //} × d ₁ × | ε _{p // −} ε _{1 //} |}
Formula (4A-2): ε _{p //} = (E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} + E _{3 //} × d ₃ × ε _{3 //} ) _{/ (E 1 // × d 1} + E 2 // × d 2 + E 3 // × d 3)
Formula (4B-1): σ⊥ = {(E ₁ ⊥ × d ₁ × | ε _p ⊥−ε ₁ ⊥ |}
Formula (4B-2): ε _p ⊥ = (E ₁ ⊥ × d ₁ × ε ₁ ⊥ + E ₂ ⊥ × d ₂ × ε ₂ ⊥ + E ₃ ⊥ × d ₃ × ε ₃ ⊥) / (E ₁ ⊥ × d ₁ + E ₂ ⊥ x d ₂ + E ₃ ⊥ x d ₃ )
Where
E _{1 //} represents the elastic modulus of the first film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₁表 し represents the elastic modulus of the first film in the direction orthogonal to the absorption axis direction of the first film, and its unit is GPa;
d ₁ represents the thickness of the first film, the unit is μm;
ε _{1 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the first film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Expresses the rate;
ε ₁ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the first film in the direction orthogonal to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents;
E _{2 //} represents the elastic modulus of the second film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₂ ⊥ represents the elastic modulus of the second film in the direction perpendicular to the absorption axis direction of the first film, and its unit is GPa;
d ₂ represents the thickness of the second film, the unit is μm;
ε _{2 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the second film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Expresses the rate;
ε ₂ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the second film in the direction orthogonal to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents.
E _{3 //} represents the elastic modulus of the third film in the direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₃表 し represents the elastic modulus of the third film in the direction orthogonal to the absorption axis direction of the first film, and its unit is GPa;
d ₃ represents the thickness of the third film, the unit is μm;
ε _{3 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the third film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Expresses the rate;
ε ₃ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the third film in the direction orthogonal to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents.
With such a configuration, when the polarizing plate of the present invention is incorporated in an image display device, it can suppress peeling of the end of the polarizing plate in an environment where temperature and humidity changes are repeated at high temperatures, and when incorporated in an image display device In addition, it is possible to suppress uneven brightness in an environment where the humidity fluctuation is large, and to suppress polarizing plate cracking in an environment where high and low temperature heat cycles are repeated. In Japanese Patent Application Laid-Open No. 2014-95880 and Japanese Patent Application Laid-Open No. 2014-164169, attention is not paid to the problem of using an image display device in an environment where high and low temperature heat cycles are repeated, and the above formula (1) is used. It did not suggest about the design of the polarizing plate relevant to (4)-(4).

<Configuration of polarizing plate>
First, the preferable structure of the polarizing plate of this invention is demonstrated.
The polarizing plate of the present invention has the second film on at least one surface side of the polarizer (first film) in both the first and second aspects of the polarizing plate of the present invention.
The 1st aspect of the polarizing plate of this invention has a 2nd film, a 1st film, and an adhesive material layer in this order, a 1st film and an adhesive material layer are in direct contact, and a 1st film is a polarizer. The absorption axis direction of the first film and the direction in which the elastic modulus of the second film is maximized are parallel. That is, the 1st aspect of the polarizing plate of this invention is a polarizing plate of the structure where the protective film of a polarizer (1st film) is one sheet. In the first aspect of the polarizing plate of the present invention, the second film and the first film are preferably in direct contact. The direct contact between the second film and the first film includes the case where the second film and the first film are laminated via an adhesive or a pressure-sensitive adhesive. It is preferable that other members other than the adhesive or the pressure-sensitive adhesive material are not included between the second film and the first film. In the first aspect of the polarizing plate of the present invention, the second film is preferably transparent.
On the other hand, the 2nd aspect of the polarizing plate of this invention has a 2nd film, a 1st film, and a 3rd film in this order, a 1st film is a polarizer, the absorption-axis direction of a 1st film, and 1st The direction in which the elastic modulus of the two films is maximum is parallel, and the absorption axis direction of the first film and the direction in which the elastic modulus of the third film is maximum are parallel. That is, the 2nd aspect of the polarizing plate of this invention is a polarizing plate of the structure which has two protective films of a polarizer (1st film). In the second aspect of the polarizing plate of the present invention, the second film and the first film are preferably in direct contact. Furthermore, in the second aspect of the polarizing plate of the present invention, it is preferable that the first film and the third film are in direct contact. The direct contact between the third film and the first film includes the case where the third film and the first film are laminated via an adhesive or an adhesive. It is preferable that other members other than the adhesive or the pressure-sensitive adhesive material are not included between the third film and the first film. In the second aspect of the polarizing plate of the present invention, the second film is preferably transparent. In the second aspect of the polarizing plate of the present invention, the third film is preferably transparent.

<Value X and value x>
In the first aspect of the polarizing plate of the present invention, the value X calculated from the formula (1) is 135 or less.
Expression (1): X = E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //}
In the second aspect of the polarizing plate of the present invention, the value x calculated from the formula (3) is 135 or less.
Equation (3): x = E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} + E _{3 //} × d ₃ × ε _{3 //}
In the polarizing plate of the present invention, the value X calculated from the formula (1) or the value x calculated from the formula (3) is preferably 120 or less, and more preferably 60 to 118.

<Value Y and value y>
In the first aspect of the polarizing plate of the present invention, the value Y calculated from the formula (2) is 0.30 or less.
Formula (2): Y = (σ _// + σ⊥) / {(E _{2 //} + E ₂ ⊥) × d ₂ }
Formula (2A-1): σ _// = {E _{1 //} × d ₁ × | ε _{p // −} ε _{1 //} |}
Formula (2A-2): ε _{p //} = (E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} ) / (E _{1 //} × d ₁ + E _{2 / /} × d ₂₎
Formula (2B-1): σ⊥ = {E ₁ ⊥ × d ₁ × | ε _p ⊥−ε ₁ ⊥ |}
Formula (2B-2): ε _p ⊥ = (E ₁ ⊥ × d ₁ × ε ₁ ⊥ + E ₂ ⊥ × d ₂ × ε ₂ ⊥) / (E ₁ ⊥ × d ₁ + E ₂ ⊥ × d ₂ )
In the second aspect of the polarizing plate of the present invention, the value y calculated from the formula (4) is 0.30 or less.
Formula (4): y = (σ _// + σ⊥) / {(E _{2 //} + E ₂ ⊥) × d ₂ + (E _{3 //} + E ₃ ⊥) × d ₃ }
Formula (4A-1): σ _// = {E _{1 //} × d ₁ × | ε _{p // −} ε _{1 //} |}
Formula (4A-2): ε _{p //} = (E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} + E _{3 //} × d ₃ × ε _{3 //} ) _{/ (E 1 // × d 1} + E 2 // × d 2 + E 3 // × d 3)
Formula (4B-1): σ⊥ = {(E ₁ ⊥ × d ₁ × | ε _p ⊥−ε ₁ ⊥ |}
Formula (4B-2): ε _p ⊥ = (E ₁ ⊥ × d ₁ × ε ₁ ⊥ + E ₂ ⊥ × d ₂ × ε ₂ ⊥ + E ₃ ⊥ × d ₃ × ε ₃ ⊥) / (E ₁ ⊥ × d ₁ + E ₂ ⊥ x d ₂ + E ₃ ⊥ x d ₃ )
In the polarizing plate of the present invention, the value Y calculated from the formula (2) or the value y calculated from the formula (4) is preferably 0.22 or less, and more preferably 0.19 or less.
Σ _// calculated from the formula (2A-1) or the formula (4A-1) is technically derived from the difference in humidity dimensional change between the first film and the polarizing plate. It is a parameter which means the component of the absorption axis direction of a 1st film among the internal stress to generate | occur | produce.
In the polarizing plate, ε _{p //} calculated from the formula (2A-2) or the formula (4A-2) is a parameter that technically means a change in humidity dimension in the absorption axis direction of the polarizing plate.
In the polarizing plate, σ⊥ calculated from the formula (2B-1) or the formula (4B-1) is technically generated in the first film due to a difference in humidity dimensional change between the first film and the polarizing plate. It is a parameter which means the component of the transmission axis direction of a 1st film among the internal stress to perform.
In the polarizing plate, ε _p算出 calculated from the formula (2B-2) or the formula (4B-2) is a parameter that technically means a change in humidity dimension in the transmission axis direction of the polarizing plate.

<Adhesive layer>
As the pressure-sensitive adhesive layer, a layer formed of a known pressure-sensitive adhesive material can be used. For example, pressure-sensitive adhesive layers described in JP-A-2003-50313 [0007] to [0079] can be used.

<First film>
The first film is a polarizer.
The humidity expansion coefficient of the polarizer can be appropriately controlled by adjusting the stretching temperature, speed, and magnification.
Further, as the first film (polarizer), for example, a film obtained by immersing and stretching a polyvinyl alcohol film in an iodine solution can be used. When using a first film (polarizer) drawn by immersing a polyvinyl alcohol film in an iodine solution, the surface treated surface of the second film or the third film is directly pasted on one or both sides of the polarizer using an adhesive. Can be matched. It is preferable that the 2nd film or the 3rd film is directly bonded with the 1st film (polarizer). As the adhesive, an aqueous solution of polyvinyl alcohol or polyvinyl acetal (for example, polyvinyl butyral) or a latex of a vinyl-based polymer (for example, polybutyl acrylate) can be used. A particularly preferred adhesive is an aqueous solution of fully saponified polyvinyl alcohol.

  The film thickness d1 of the first film is preferably 25 μm or less, more preferably 0.01 to 23 μm, particularly preferably 1 to 20 μm, and even more preferably 5 to 18 μm.

When the film thickness of the second film is d2, d2 / d1 is preferably 0.5 to 5.0, more preferably 0.7 to 4.0, and particularly preferably 0.8 to 3.0. 1.0 to 2.5 is more particularly preferable.
When the film thickness of the third film is d3, d3 / d1 is preferably 0.5 to 5.0, more preferably 0.7 to 4.0, and particularly preferably 0.8 to 3.0. 1.0 to 2.5 is more particularly preferable.

E _{1 //} represents the elastic modulus of the first film in a direction parallel to the absorption axis direction of the first film, and its unit is GPa. The direction parallel to the absorption axis direction of the first film is preferably parallel to the direction in which the sound wave propagation speed of the first film is maximized. The elastic modulus of the first film in the direction parallel to the absorption axis direction of the first film is preferably 10.0 to 40.0 GPa, more preferably 20.0 to 30.0 GPa, and further 21.0 to 30.0 GPa. preferable.
E ₁を represents the elastic modulus of the first film in a direction orthogonal to the absorption axis direction of the first film, and its unit is GPa. The elastic modulus of the first film in the direction orthogonal to the absorption axis direction of the first film is preferably 2.5 to 10.0 GPa, more preferably 3.0 to 7.5 GPa, and further 3.5 to 6.0 GPa. preferable.
ε _{1 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the first film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Represents a rate. ε _{1 //} is preferably 0.01 to 0.38%, more preferably 0.05 to 0.30%, particularly preferably 0.07 to 0.20%, and more preferably 0.07 to 0.14%. Particularly preferred.
ε ₁ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the first film in the direction orthogonal to the absorption axis direction of the first film relative to the dimension at the relative humidity of 60%. Represents. ε ₁が is preferably 1.00 to 2.00%, more preferably 1.20 to 1.80%, and particularly preferably 1.40 to 1.60%.

  In the present invention, the parallel or perpendicular to the absorption axis direction of the first film means that it is within an angle range of ± 10 ° with respect to the parallel or orthogonal direction to the absorption axis direction of the first film, and ± 5 °. Is preferable, and an angle of ± 1 ° is more preferable.

In the present invention, the maximum direction of sound wave propagation means that the direction of sound velocity propagation is in an angle range of ± 10 ° with respect to the maximum direction, and preferably intersects at an angle of ± 5 °. More preferably, they intersect at an angle of °.
The direction in which the sound wave propagation velocity is orthogonal to the maximum direction means that the sound velocity propagation direction intersects with the maximum direction at an angle of 90 ° ± 10 °, and intersects with an angle of 90 ° ± 5 °. It is more preferable that they intersect at an angle of 90 ° ± 1 °.

<Second film and third film>
The second film and the third film can be used as a polarizing plate protective film for the polarizing plate of the present invention. In the first aspect of the polarizing plate of the present invention, the polarizer as the first film and one polarizing plate protective film (optical film) for protecting one surface thereof and the other surface of the polarizer are in direct contact. In particular, the second film is preferably used as a polarizing plate protective film. The 2nd aspect of the polarizing plate of this invention contains a polarizer and two polarizing plate protective films (optical film) which protect the both surfaces, and a 2nd film and a 3rd film are at least one polarizing plate protective film. It is particularly preferable to use it.
When the second film and the third film are used as a polarizing plate protective film, the second film and the third film are subjected to surface treatment (also described in JP-A-6-94915 and JP-A-6-118232) to be hydrophilic. For example, it is preferable to perform glow discharge treatment, corona discharge treatment, or alkali saponification treatment. As the surface treatment, alkali saponification treatment is most preferably used.
(Characteristics of the second film and the third film)
-Film thickness of the second film and the third film-
The film thicknesses of the second film and the third film are not particularly limited, and may be 1 to 80 μm, for example. In the polarizing plate of the present invention, both the film thickness d ₂ of the second film and the film thickness d ₃ of the third film are preferably 35.0 μm or less, and preferably 30.0 or less. Polarizing plate cracking in an environment where high-temperature and low-temperature heat cycles are repeated even when the film is a thin film is suppressed, and changes in temperature and humidity are repeated at high temperatures when incorporated in an image display device It is more preferable from the standpoint that it is possible to suppress the peeling of the edges of the film, and to suppress luminance unevenness in an environment where the humidity fluctuation is large when incorporated in an image display device.

-Elastic modulus-
E _{2 //} represents the elastic modulus of the second film in a direction parallel to the absorption axis direction of the first film, and its unit is GPa. The direction parallel to the absorption axis direction of the first film is preferably parallel to the direction in which the sound wave propagation speed of the second film is maximized. The elastic modulus of the second film in a direction parallel to the absorption axis direction of the first film is preferably 5.5 to 10.0 GPa, more preferably 5.7 to 7.5 GPa, and further 5.9 to 7.0 GPa. preferable.
E ₂表 し represents the elastic modulus of the second film in the direction orthogonal to the absorption axis direction of the first film, and its unit is GPa. The elastic modulus of the second film in the direction orthogonal to the absorption axis direction of the first film is preferably 2.5 to 10.0 GPa, more preferably 3.0 to 7.5 GPa, and further 3.5 to 6.0 GPa. preferable.

In the polarizing plate of the present invention, the value obtained by dividing the elastic modulus E _{2 //} of the second film by the elastic modulus E ₂の of the second film (E _{2 //} / E ₂ ⊥) is 1.20 or more. Polarizing plate cracking in an environment where high temperature and low temperature heat cycles are repeated is suppressed, and when it is incorporated in an image display device, it is possible to suppress end peeling of the polarizing plate in an environment where temperature and humidity changes are repeated at high temperatures, From the viewpoint of suppressing luminance unevenness in an environment where the humidity fluctuation is large when incorporated in an image display device, it is preferably 1.40 or more, and particularly preferably 1.50 or more.

E _{3 //} represents the elastic modulus of the third film in a direction parallel to the absorption axis direction of the first film, and its unit is GPa. The elastic modulus of the third film in a direction parallel to the absorption axis direction of the first film is preferably 5.5 to 10.0 GPa, more preferably 5.7 to 7.5 GPa, and further preferably 3.5 to 6.0 GPa. preferable.
E ₃表 し represents the elastic modulus of the third film in the direction orthogonal to the absorption axis direction of the first film, and its unit is GPa. The elastic modulus of the third film in the direction orthogonal to the absorption axis direction of the first film is preferably 1.2 to 5.5 GPa, more preferably 1.5 to 5.0 GPa, and further 2.0 to 4.5 GPa. preferable.

-Humidity dimensional change rate-
ε _{2 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the second film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Represents a rate. ε _{2 //} is preferably 0.01 to 0.38%, more preferably 0.05 to 0.30%, particularly preferably 0.07 to 0.28%, and more preferably 0.09 to 0.20%. Particularly preferred.
ε ₂ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the second film in the direction orthogonal to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents. ε ₂が is preferably 0.13 to 0.80%, more preferably 0.20 to 0.70%, particularly preferably 0.30 to 0.65%, and particularly preferably 0.45 to 0.60%. preferable.
ε _{3 //} is the dimensional change in humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the third film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Represents a rate. ε _{3 //} is preferably 0.01 to 0.38%, more preferably 0.05 to 0.30%, particularly preferably 0.07 to 0.28%, and more preferably 0.09 to 0.20%. Particularly preferred.
ε ₃ ⊥ is the humidity dimensional change rate expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the third film in the direction orthogonal to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents. ε ₃が is preferably 0.13 to 0.80%, more preferably 0.20 to 0.70%, particularly preferably 0.30 to 0.65%, and particularly preferably 0.45 to 0.60%. preferable.
The humidity dimensional change rate can be controlled by stretching the second film or the third film.

-Equilibrium moisture content of second film and third film-
Although the moisture content (equilibrium moisture content) of the second film and the third film is not particularly limited, when used as a protective film for a polarizing plate, the adhesiveness with a water-soluble polymer such as polyvinyl alcohol is not impaired. Regardless of the film thickness, the water content at 25 ° C. and 80% relative humidity is preferably 0 to 4% by mass. More preferably, it is 0.1-3.5 mass%, and it is especially preferable that it is 1-3 mass%. When the equilibrium moisture content is 4% by mass or less, it is preferable that the dependence of retardation due to a change in humidity does not become too large when used as a support for a retardation film.
The moisture content was measured by measuring the second film and the third film sample 7 mm × 35 mm with a moisture measuring device and sample drying apparatuses “CA-03” and “VA-05” (both manufactured by Mitsubishi Chemical Corporation). Measured by the method. It was calculated by dividing the amount of water (g) by the sample mass (g).

-Moisture permeability of second film and third film-
The moisture permeability of the second film and the third film is measured under the conditions of 40 ° C. and relative humidity of 90% based on JIS Z-0208. Although the water vapor transmission rate of a 2nd film is not specifically limited, It is preferable that it is 50-1500 g / (m < ² > * 24h). More preferably ^{100~1000g / (m 2 · 24h)} , particularly preferably ^{200~800g / (m 2 · 24h)} . If the moisture permeability is within this range, it is preferable because both the workability of the polarizing plate and the durability of the polarizing plate against humidity or wet heat can be achieved. Further, the moisture permeability of the third film used on the opposite side of the second film across the polarizer is not particularly limited, but is preferably low and is 3 to 1000 g / (m ² · 24 h) or less. Is preferably 5 to 500 g / (m ² · 24 h), more preferably 10 to 100 g / (m ² · 24 h), and more preferably 10 to 50 g / (m ² · 24 h). Is particularly preferred. If it is this range, both polarizing plate workability and durability of a polarizing plate with respect to humidity or wet heat can be made compatible, and the curvature of an image display apparatus can be improved more effectively.

-Haze of second film and third film-
The hazes of the second film and the third film are preferably smaller, and preferably 0.01 to 2.0%. More preferably, it is 1.0% or less, More preferably, it is 0.5% or less. Haze can be measured according to JIS K-6714 using a haze meter (HGM-2DP, Suga Test Instruments), etc. at 25 ° C. and 60% RH for the second film and the third film sample 40 mm × 80 mm. it can.

-Retardation-
It is important for the second film and the third film to appropriately adjust Re and Rth (defined by the following formula (I) and formula (II)) measured at a wavelength of 590 nm, depending on the application. This value depends on the chemical structure of the polymer constituting the second film and the third film (for example, the type and degree of substitution for cellulose esters), the type and amount of the compound having the above-mentioned repeating unit, It can be controlled by the film thickness, the process conditions during film formation, the stretching process, and the like.
Reducing the retardation of the second film and the third film, for example, when used as a polarizing plate protective film of an IPS mode liquid crystal display device, used as a front side (viewing side) protective film of the viewing side polarizing plate The second film to be used and the third film used as the rear side (backlight side) protective film of the viewing side polarizing plate preferably both satisfy the following formulas (IIIa) and (IVa), and further used as a protective film. A functional layer to be described later can also be provided by using the obtained optical film as a support. Thereby, for example, the contrast of the display screen of the liquid crystal display device can be improved, and viewing angle characteristics and color can be improved.
Formula (I) Re = (nx−ny) × d (nm)
Formula (II) Rth = {(nx + ny) / 2−nz} × d (nm)
Formula (IIIa) Re <30 nm
Formula (IVa) | Rth | <80 nm
(Where nx is the refractive index in the slow axis direction in the film plane, ny is the refractive index in the fast axis direction in the film plane, nz is the refractive index in the thickness direction of the film, and d is (The thickness of the film (nm).)
In this case, the orientation of the in-plane slow axis is not particularly limited, but is preferably substantially parallel or substantially orthogonal to the orientation in which the elastic modulus of the film is maximum in the in-plane. As for a 2nd film and a 3rd film, it is more preferable that Re is 0-20 nm, and it is more preferable that Rth is -20-60 nm.
In the third film, Re is more preferably 0 to 10 nm, and Rth is more preferably −10 to 20 nm. When the third film is used as a protective film on the liquid crystal cell side of a polarizing plate of a liquid crystal display device, if Re and Rth are in the above ranges, light leakage from an oblique direction can be further improved and display quality can be improved. . This embodiment can be particularly preferably used in an IPS liquid crystal display device in which the liquid crystal cell and the film do not directly optically compensate.

Re and Rth can be measured as follows.
In this specification, Re and Rth (unit: nm) are determined according to the following method. First, the film was conditioned at 25 ° C. and 60% relative humidity for 24 hours, and then a prism coupler (MODEL2010 Prism Coupler: manufactured by Metricon) was used. The average refractive index (n) represented by (B) is obtained, and Re and Rth are obtained by the method described later.
Formula (B): n = (n _TE × 2 + n _TM ) / 3
[ _Where n _TE is a refractive index measured with polarized light in the film plane direction, and n _TM is a refractive index measured with polarized light in the film surface normal direction. ]
In this specification, Re (λnm) and Rth (λnm) respectively represent in-plane retardation and retardation in the thickness direction at a wavelength λ (unit: nm). Re (λnm) is measured by making light having a wavelength of λnm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments).
When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λnm) is calculated by the following method.
Rth (λnm) is Re (λnm), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is the tilt axis (rotation axis) (if there is no slow axis, any film surface in-plane The direction of the rotation axis is the film normal direction), and the light of wavelength λ nm is incident from the inclined direction in steps of 10 ° from the normal direction to 50 ° on one side, measuring 6 points in total. KOBRA 21ADH or WR calculates based on the retardation value, the average refractive index, and the input film thickness value.
In the above, there is no description regarding λ, and when only Re and Rth are described, it represents a value measured using light having a wavelength of 590 nm. In addition, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the in-plane slow axis as the rotation axis from the normal direction, the retardation value at a tilt angle larger than the tilt angle is After changing the sign to negative, KOBRA 21ADH or WR calculates.
In addition, the retardation value is measured from two inclined directions with the slow axis as the tilt axis (rotary axis) (in the case where there is no slow axis, the arbitrary direction in the film plane is the rotary axis), Based on the value, the average refractive index, and the input film thickness value, Rth can also be calculated from the following equations (3) and (4).

Formula (3)

[In the formula, Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. Further, nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction orthogonal to nx in the plane, nz represents the refractive index in the thickness direction orthogonal to nx and ny, and d Represents the film thickness of the film. ]

Formula (4): Rth = ((nx + ny) / 2−nz) × d
When the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film without a so-called optical axis, Rth (λnm) is calculated by the following method.
Rth (λnm) is Re (λnm), and the in-plane slow axis (determined by KOBRA 21ADH or WR) is tilt axis (rotation axis) from −50 degrees to +50 degrees with respect to the film normal direction. In 11 degree steps, light having a wavelength of λ nm is incident from each inclined direction and measured at 11 points, and KOBRA 21ADH or WR is calculated based on the measured retardation value, average refractive index, and input film thickness value. By inputting these average refractive index and film thickness, KOBRA 21ADH or WR calculates nx, ny, and nz. Nz = (nx−nz) / (nx−ny) is further calculated from the calculated nx, ny, and nz.

-Humidity dependence of retardation-
The humidity dependency (ΔRe) of Re and the humidity dependency (ΔRth) of Rth are the retardation values in the in-plane direction and the film thickness direction when the relative humidity is H (unit:%): Re (H%) and Rth (H%) is calculated based on the following formula.
ΔRe = Re (10%) − Re (80%)
ΔRth = Rth (10%) − Rth (80%)
Re (H%) and Rth (H%) are bonded to a glass plate via an adhesive at 25 ° C. and 60% relative humidity after the film is conditioned for 24 hours at 25 ° C. and 60% relative humidity. . After adjusting the humidity at 60 ° C. and 90% relative humidity for 48 hours, and adjusting the humidity at 25 ° C. and relative humidity H% for 24 hours, at 25 ° C. and relative humidity H% in the same manner as described above, This is a value obtained by measuring and calculating a retardation value when the measurement wavelength at a relative humidity of H% is 590 nm. In addition, when noting clearly about relative humidity and being only described with Re, the value measured by the above-mentioned relative humidity 60% is represented.
It is preferable that the retardation value when the humidity of the second film and the third film is changed satisfies the following relational expression.
| ΔRe | <30 nm, and
| ΔRth | <30 nm
It is more preferable to satisfy the following relational expression.
| ΔRe | <15 nm and
| ΔRth | <15 nm
It is more preferable to satisfy the following relational expression.
| ΔRe | <10 nm and
| ΔRth | <10 nm
It is most preferable that the following relational expression is satisfied.
| ΔRe | <5 nm and
| ΔRth | <5 nm
By controlling the retardation value when the humidity is changed, the retardation change when the external environment changes can be reduced, and a highly reliable liquid crystal display device can be provided. In addition, by reducing ΔRth of the second film and the third film, there is also a preferable effect that circular color unevenness that is visually recognized when the liquid crystal display device is observed obliquely on a display surface under specific conditions is improved. can get. Further, when the second film and the third film are disposed between a film and a polarizer having an effect of imparting a 3D display function to the liquid crystal display device, there is a preferable effect for improving crosstalk at the time of 3D display. In order to effectively reduce ΔRe and ΔRth, it is also preferable to use the aforementioned humidity dependency reducing agent in combination.

-Photoelastic coefficient-
When the second film and the third film are used as a polarizing plate protective film, birefringence (Re, Rth) may change due to stress due to the contraction of the polarizer. Such a change in birefringence due to the stress can be measured as a photoelastic coefficient, but the range is preferably 15 × 10 ¹² Pa ⁻¹ or less (15Br or less), from −5 × 10 ¹² Pa ⁻¹ to 12 × 10 ¹² Pa ⁻¹ is more preferable, and −2 × 10 ¹² Pa ^{−1 to} 11 × 10 ¹² Pa ⁻¹ is still more preferable.

-Contact angle of optical film surface by alkali saponification treatment-
When the second film and the third film contain cellulose acylate, an alkali saponification treatment can be cited as an effective means of surface treatment when used as a polarizing plate protective film. In this case, the contact angle between the second film surface and the third film surface after the alkali saponification treatment is preferably 55 ° or less. More preferably, it is 50 ° or less, and further preferably 45 ° or less.

-Glass transition temperature-
The glass transition temperature is a boundary temperature at which the mobility of the polymer constituting the second film and the third film changes greatly. In the present invention, the glass transition temperature is 20 mg of the second film and the third film in a measurement pan of a differential scanning calorimeter (DSC), and this is heated from 30 ° C. to 120 ° C. at 10 ° C./min in a nitrogen stream. Then, after maintaining for 15 minutes, it is cooled to −30 ° C. at −20 ° C./min, and then the temperature is raised again from 30 ° C. to 250 ° C., and it can be obtained as the temperature at which the baseline starts to change from the low temperature side. The Tg of the second film and the third film is preferably 100 to 230 ° C, more preferably 110 to 200 ° C, and still more preferably 115 to 180 ° C. When Tg is 100 ° C. or higher, the contraction of the polarizing plate is suppressed when the image display device is exposed to a high temperature. For example, the image display device is not warped to cause a light leakage failure, which is preferable. Moreover, even when the polarizing plate is exposed to an environment where high and low temperature heat cycles are repeated, the contraction of the polarizing plate is suppressed and cracking of the polarizing plate is suppressed, which is preferable. On the other hand, when the Tg is 230 ° C. or lower, the heating temperature for stretching the film can be suppressed to a temperature that does not cause a problem in practical characteristics. On the other hand, since it becomes possible to stretch uniformly even at an industrially reasonable stretching temperature, defects such as craze will not occur in the film, for example, haze of the film can be suppressed or brittleness can be prevented. It is preferable because it can be improved. In addition, Tg falls when a residual solvent is contained in the film.

(Composition of the second film and the third film)
-Polymer-
As the polymer used for the second film and the third film, a cellulose-based polymer (hereinafter referred to as cellulose ester) represented by triacetyl cellulose, which has been conventionally used as a transparent protective film for polarizing plates, can be preferably used. .
Details of the cellulose ester will be described below.

-Cellulose ester-
The second film and the third film preferably contain a cellulose ester.
The second film and the third film contain a cellulose ester, and the cellulose ester content is preferably 30 to 99% by mass, more preferably 40 to 90% by mass, and 50 to 80% by mass. More preferably, a film excellent in polarizing plate processability can be produced.
The cellulose ester used for the second film and the third film is an ester of raw material cellulose and acid. In the polarizing plate of the present invention, it is preferable that the second film contains at least cellulose acylate as a polymer. The cellulose acylate is preferably a carboxylic acid ester having about 2 to 22 carbon atoms, and more preferably a lower fatty acid ester having 6 or less carbon atoms. Examples of the method for measuring the degree of substitution of acetic acid and / or a fatty acid having 3 to 22 carbon atoms substituted on the hydroxyl group of cellulose include a method according to ASTM D-817-91 and an NMR method. In the case of cellulose acylate having about 2 to 22 carbon atoms, a condensate having a repeating unit is used, and in particular, in the case of cellulose acetate having 2 carbon atoms, in addition to this, an adduct having a repeating unit is used. In addition, it is possible to improve luminance unevenness of the liquid crystal display device.
Examples of cellulose as a raw material for cellulose ester include cotton linter and wood pulp (hardwood pulp, softwood pulp). Cellulose esters obtained from any raw material cellulose can be used, and they may be mixed and used in some cases. Detailed descriptions of these raw material celluloses can be found, for example, in the course of plastic materials (17) Fibrous resin (manufactured by Marusawa and Uda, published by Nikkan Kogyo Shimbun, published in 1970) and JIII Journal of Technical Disclosure 2001-1745 (page 7). To page 8) can be used, and the cellulose is not particularly limited.

  In the cellulose acylate used in the second film and the third film, the degree of substitution of cellulose with a hydroxyl group is not particularly limited, but when used for polarizing plate protective film and optical film, the film has appropriate moisture permeability and moisture absorption. In order to impart properties, it is preferable that the acyl substitution degree of the cellulose hydroxyl group is 2.00 to 3.00. Furthermore, the substitution degree is preferably 2.30 to 2.98, more preferably 2.70 to 2.96, and still more preferably 2.80 to 2.94. Further, the acyl substitution degree (DSs) of cellulose acylate contained in a 1 μm region from the film surface and the acyl substitution degree (DSc) of cellulose acylate contained in a 1 μm region from the thickness direction center of the optical film are DSs. ≦ DSc is preferably satisfied. DSs can be measured, for example, by cutting a region of 1 μm from the film surface with a razor blade or the like, and the obtained powder can be measured by a known method. DSc is also used to cut the film to the center in the thickness direction (for example, 50 μm In the case of this film, after cutting up to 25 μm, a 1 μm region is further cut out).

  Of the acetic acid and / or the fatty acid having 3 to 22 carbon atoms substituted for the hydroxyl group of cellulose, the acyl group having 2 to 22 carbon atoms may be an aliphatic group or an aromatic group, and is not particularly limited. It may be a mixture of more than one type. These are, for example, cellulose alkylcarbonyl esters, alkenylcarbonyl esters, aromatic carbonyl esters, aromatic alkylcarbonyl esters, and the like, each of which may further have a substituted group. These preferred acyl groups include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, iso-butanoyl, t-butanoyl, cyclohexanecarbonyl, Examples include oleoyl, benzoyl, naphthylcarbonyl, and cinnamoyl groups. Among these, acetyl, propionyl, butanoyl, dodecanoyl, octadecanoyl, t-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like are preferable, and acetyl, propionyl and butanoyl are more preferable.

  Among these, acetyl groups, mixed esters of acetyl groups and propyl groups are preferred, and acetyl groups are particularly preferred from the viewpoints of ease of synthesis, cost, ease of control of substituent distribution, and the like.

  The degree of polymerization of cellulose acylate preferably used for the second film and the third film is 180 to 700 in terms of viscosity average degree of polymerization. In cellulose acetate, 180 to 550 is more preferable, 180 to 400 is more preferable, 180 -350 is particularly preferred. If the degree of polymerization is too high, the viscosity of the cellulose acylate dope solution tends to be high, and film production tends to be difficult due to casting. If the degree of polymerization is too low, the strength of the produced film tends to decrease. The average degree of polymerization can be measured by Uda et al.'S intrinsic viscosity method (Kazuo Uda, Hideo Saito, Journal of Textile Society, Vol. 18, No. 1, pages 105-120, 1962). This is described in detail in JP-A-9-95538.

  The molecular weight distribution of cellulose acylate preferably used for the second film and the third film is evaluated by gel permeation chromatography, and its polydispersity index Mw / Mn (Mw is a mass average molecular weight, Mn is a number average molecular weight). Is small and the molecular weight distribution is preferably narrow. The specific value of Mw / Mn is preferably 1.0 to 4.0, more preferably 2.0 to 3.5, and most preferably 2.3 to 3.4. preferable.

  Regarding the cellulose acylate used in the second film and the third film, the raw material cotton and the synthesis method thereof are 7 according to the Japan Society of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Invention Association). It is described in detail on pages 12-12.

  Cellulose acylate can be used by mixing two or more kinds of cellulose acylates which are single or different from the viewpoints of substituents, substitution degree, polymerization degree, molecular weight distribution and the like.

-Plasticizer-
The cellulose acylate film used for the second film and the third film preferably contains at least one plasticizer.
The plasticizer is presumed to suppress the aggregation of polymer chains, and is considered to contribute to improving the properties in terms of haze and brittleness.
From the viewpoint of film viscoelasticity, the content of the plasticizer is preferably 5 parts by mass or more and 25 parts by mass or less, and more preferably 6 parts by mass or more and 20 parts by mass or less with respect to 100 parts by mass of cellulose acylate.
A known plasticizer for a polarizing plate protective film can be used as the plasticizer. For example, a phosphate ester compound can be used. Examples of the phosphoric acid ester compound include those described in paragraph No. 0198 of JP-A-2005-104148, paragraphs 0024 to 0027 of JP-A-2005-41911, paragraphs 0021 to 0027 of JP-A-2005-154383, and the like. And the contents of this publication are incorporated herein.

--Sugar ester compound--
The plasticizer preferably contains various lanose structural units conventionally used in cellulose acylate films, and more preferably all sugar residues are pyranose structural units or furanose structural units. Moreover, when sugar ester is comprised from polysaccharide, it is preferable that both a pyranose structural unit or a furanose structural unit is included.

  The sugar residue of the sugar ester compound may be derived from 5 monosaccharides or 6 monosaccharides, but is preferably derived from 6 monosaccharides.

  The number of structural units contained in the sugar ester compound is preferably 1 to 12, more preferably 1 to 6, and particularly preferably 1 or 2.

  The sugar ester compound is more preferably a sugar ester compound containing 1 to 12 pyranose structural units or furanose structural units in which at least one hydroxyl group is esterified, and a pyranose structure in which at least one hydroxyl group is esterified More preferably, it is a sugar ester compound containing one or two units or furanose structural units.

  Examples of monosaccharides or saccharides containing 2-12 monosaccharide units include, for example, erythrose, threose, ribose, arabinose, xylose, lyxose, allose, altrose, glucose, fructose, mannose, gulose, idose, galactose, Tulose, trehalose, isotrehalose, neotrehalose, trehalosamine, caudibiose, nigerose, maltose, maltitol, isomaltose, sophorose, laminaribiose, cellobiose, gentiobiose, lactose, lactosamine, lactitol, lactulose, melibiose, primiverose, lutinose Sucrose, sucralose, tularose, vicyanose, cellotriose, cacotriose, gentianose, isomaltorio , Isopanose, maltotriose, manninotriose, melenitoose, panose, planteose, raffinose, solatriose, umbelliferose, lycotetraose, maltotetraose, stachyose, maltopentaose, verbus course, maltohexaose, Examples include α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, δ-cyclodextrin, xylitol, sorbitol and the like.

  Preferably, ribose, arabinose, xylose, lyxose, glucose, fructose, mannose, galactose, trehalose, maltose, cellobiose, lactose, sucrose, sucralose, α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, δ-cyclodextrin Xylitol, sorbitol, more preferably arabinose, xylose, glucose, fructose, mannose, galactose, maltose, cellobiose, sucrose, β-cyclodextrin, γ-cyclodextrin, particularly preferably xylose, glucose, fructose , Mannose, galactose, maltose, cellobiose, sucrose, xylitol, sorbitol.

It is more preferable that the sugar ester compound used for the second film and the third film has a structure represented by the following general formula (1A) including the substituent used.
Formula _{(1A) (OH) p -G-} (L 1 -R 11) q (O-R 12) r
In General Formula (1A), G represents a sugar residue, L ¹ represents any ^one of —O—, —CO—, and —NR ¹³ —, and R ¹¹ represents a hydrogen atom or a monovalent substituent. R ¹² represents a monovalent substituent bonded by an ester bond, and R ¹³ represents a hydrogen atom or a monovalent substituent. p, q and r each independently represents an integer of 0 or more, and p + q + r is equal to the number of hydroxyl groups when G is assumed to be an unsubstituted saccharide having a cyclic acetal structure.

  The preferable range of G is the same as the preferable range of the sugar residue.

L ¹ is preferably —O— or —CO—, and more preferably —O—. When L ¹ is —O—, it is particularly preferably a linking group derived from an ether bond or an ester bond, and more preferably a linking group derived from an ester bond.
Further, when there are a plurality of L ^{1 s} , they may be the same as or different from each other.

At least one of R ¹¹ and R ¹² preferably has an aromatic ring.

In particular, when L ¹ is —O— (that is, when R ¹¹ and R ¹² are substituted on the hydroxyl group in the sugar ester compound), R ¹¹ , R ¹² and R ¹³ are substituted or unsubstituted acyl groups. Are preferably selected from a substituted or unsubstituted aryl group, a substituted or unsubstituted alkyl group, a substituted or unsubstituted amino group, a substituted or unsubstituted acyl group, a substituted or unsubstituted alkyl, It is more preferably a group or a substituted or unsubstituted aryl group, particularly preferably an unsubstituted acyl group, a substituted or unsubstituted alkyl group, or an unsubstituted aryl group.
Further, when there are a plurality of R ¹¹ , R ¹² and R ¹³ , they may be the same as or different from each other.

p represents an integer of 0 or more, and a preferable range is the same as the preferable range of the number of hydroxyl groups per monosaccharide unit described later.
r preferably represents a number larger than the number of pyranose structural units or furanose structural units contained in G.
q is preferably 0.
Since p + q + r is equal to the number of hydroxyl groups when G is assumed to be an unsubstituted saccharide having a cyclic acetal structure, the upper limit values of p, q, and r are uniquely determined according to the structure of G.

  Preferable examples of the substituent of the sugar ester compound include an alkyl group (preferably an alkyl group having 1 to 22 carbon atoms, more preferably an alkyl group having 1 to 12 carbon atoms, and particularly preferably an alkyl group having 1 to 8 carbon atoms, such as a methyl group and an ethyl group. Group, propyl group, hydroxyethyl group, hydroxypropyl group, 2-cyanoethyl group, benzyl group, etc.), aryl group (preferably 6 to 24 carbon atoms, more preferably 6 to 18 carbon atoms, particularly preferably 6 to 12 aryl groups). , For example, phenyl group, naphthyl group), acyl group (preferably having 1 to 22 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms, for example, acetyl group, propionyl group, butyryl). Group, pentanoyl group, hexanoyl group, octanoyl group, benzoyl group, toluyl group, phthalyl group, etc.), amide group (preferably An amide having 1 to 22 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably an amide having 2 to 8 carbon atoms such as a formamide group or an acetamido group, preferably an imide group (preferably having 4 to 22 carbon atoms, more preferably carbon. And an amide group having 4 to 12 carbon atoms, particularly preferably 4 to 8 carbon atoms, such as a succinimide group and a phthalimide group. Among them, an alkyl group or an acyl group is more preferable, a methyl group, an acetyl group, or a benzoyl group is more preferable, and among them, a benzoyl group is particularly preferable.

  The number of hydroxyl groups per structural unit in the sugar ester compound (hereinafter also referred to as hydroxyl group content) is preferably 3 or less, more preferably 2 or less, and 1 or 2. Is particularly preferred. By controlling the hydroxyl group content within the range, the transfer of sugar ester compounds to the polarizer layer and the destruction of the PVA-iodine complex at high temperature and high humidity can be suppressed, and the deterioration of the polarizer performance at high temperature and high humidity can be suppressed. This is preferable.

  As a method for obtaining the sugar ester compound, it is commercially available from Tokyo Chemical Industry Co., Ltd., Aldrich, etc. as a commercial product, or known ester derivatization methods for commercially available carbohydrates (for example, JP-A-8 The method can be synthesized by the method described in JP-A-245678.

  The sugar ester compound has a number average molecular weight of preferably 200 to 3500, more preferably 200 to 3000, and particularly preferably 250 to 2000.

  Although the specific example of the sugar ester compound which can be preferably used for the 2nd film and the 3rd film below is given, the present invention is not limited to the following modes.

Sugar ester compound (1):

糖エステル化合物（１）におけるＲ³の平均置換度は４〜８であることが好ましく、６〜８であること、すなわち後述の可塑剤Ｂ−１またはＤ−１がより好ましい。糖エステル化合物（１）におけるＲ³の平均置換度は６または７であることが特に好ましく、６であること、すなわち後述の可塑剤Ｂ−１がより特に好ましい。

The average degree of substitution of R ^{3 in} the sugar ester compound (1) is preferably 4 to 8, more preferably 6 to 8, that is, plasticizer B-1 or D-1 described later. The average degree of substitution of R ^{3 in} the sugar ester compound (1) is particularly preferably 6 or 7, more preferably 6, that is, a plasticizer B-1 described later.

Sugar ester compound (2): Ac represents an acetyl group.

Sugar ester compound (3):

Sugar ester compound (4): Bz represents a benzoyl group.

In the following structural formulae, R each independently represents an arbitrary substituent, and a plurality of R may be the same or different. In the following structure, each of the substituents 1 and 2 represents an arbitrary R. The degree of substitution represents the number of R represented by a substituent. “None” represents that R is a hydrogen atom.
The ClogP value is a value obtained by calculating the common logarithm logP of the distribution coefficient P between 1-octanol and water. For the calculation of the ClogP value, the Daylight Chemical
Information Systems system: CLOGP program embedded in PCModels was used.

The sugar ester compound is preferably contained in an amount of 2 to 30 parts by mass, more preferably 5 to 20 parts by mass with respect to 100 parts by mass of cellulose acylate.
Moreover, when using together a polyester plasticizer with a sugar ester compound, the addition amount (mass part) of the sugar ester compound with respect to the addition amount (mass part) of a polyester plasticizer is 0.5-10 times (mass ratio). It is preferable to add, and it is more preferable to add 0.5 to 8 times (mass ratio).

--Compound having a repeating unit--
In the second film and the third film, a compound having a repeating unit can also be used as a plasticizer.

The number average molecular weight (Mn) of the compound having a repeating unit is preferably 600 to 5000, more preferably 600 to 3000, still more preferably 650 to 2300, and most preferably 700 to 1800. If the number average molecular weight of the compound having a repeating unit is 600 or more, the volatility is low, and film failure or process due to volatilization under high temperature conditions when the second film and the third film are formed or stretched. Contamination is hardly caused, and at the same time, by increasing the number average molecular weight, it is possible to suppress a change in retardation when held in a moist heat environment. Moreover, if it is 5000 or less, compatibility with the polymer which comprises a 2nd film and a 3rd film can be ensured, and it becomes difficult to produce a bleed-out. However, the compound having a repeating unit in the present invention is not limited to only a compound having such a repeating unit portion, and may be a mixture with a compound having no repeating unit.
The number average molecular weight of the compound having a repeating unit can be measured and evaluated by gel permeation chromatography.
The compound having a repeating unit may be a liquid or a solid under the ambient temperature or humidity to be used (generally room temperature conditions, so-called 25 ° C., relative humidity 60%). Further, the smaller the color, the better, and it is particularly preferable that the color is colorless. Thermally, it is preferably stable at a higher temperature, and the decomposition start temperature is preferably 150 ° C. or higher, more preferably 200 ° C. or higher.
Hereinafter, the compound having a repeating unit used in the second film and the third film will be described in detail with specific examples, but the compound having a repeating unit that can be used in the present invention is limited to these. is not.

--- Types of compounds having repeating units ---
Examples of the condensate include a condensate of polyhydric alcohol and polybasic acid, a condensate of polyhydric ether alcohol and polybasic acid, and a polyhydric alcohol and polybasic acid. A condensate of a condensate and an isocyanate compound can be preferably exemplified, and examples of the adduct include an adduct of acrylic ester and an adduct of methacrylic ester. Further, the number average of at least one selected from polyether compounds, polyurethane compounds, polyether polyurethane compounds, polyamide compounds, polysulfone compounds, polysulfonamide compounds, and other polymer compounds described later. A compound having a molecular weight of 600 or more can also be used.

At least one of them is preferably a condensate of polyhydric alcohol and polybasic acid, a condensate of polyhydric ether alcohol and polybasic acid, an adduct of acrylic ester, an adduct of methacrylic ester, A condensate of polyhydric alcohol and polybasic acid, a condensate of polyhydric ether alcohol and polybasic acid are more preferable, and a condensate of polyhydric alcohol and polybasic acid is still more preferable.
Below, the compound which has a repeating unit preferably used for a 2nd film and a 3rd film is described according to a kind.

--Condensate of polyhydric alcohol and polybasic acid ---
First, the condensate of a polyhydric alcohol and a polybasic acid is demonstrated. A preferred condensate of a polyhydric alcohol and a polybasic acid is not particularly limited, and is obtained by a reaction between a dibasic acid and a glycol. Carrying out so-called terminal sealing by reacting carboxylic acid or monoalcohol is preferable because it can suppress a change in retardation when held in a humid heat environment. In such a condensate, the hydroxyl value is lowered as compared with a condensate having an unblocked end, and the hydroxyl value is preferably less than 40 mgKOH / g, more preferably 20 mgKOH / g or less, and 10 mgKOH. / G or less is more preferable.
In the condensate of the polyhydric alcohol and the polybasic acid, the polyhydric alcohol preferably contains at least a polyhydric alcohol having 3 or more carbon atoms from the viewpoint of suppressing contamination of the casting support.
The condensate of a polyhydric alcohol and a polybasic acid is preferably synthesized from a glycol having 2 to 12 carbon atoms and a dibasic acid having 4 to 12 carbon atoms.

As a dibasic acid used for the condensate of a polyhydric alcohol and a polybasic acid, an aliphatic dicarboxylic acid residue or alicyclic dicarboxylic acid residue having 3 to 12 carbon atoms or an aromatic having 8 to 12 carbon atoms is used. A dicarboxylic acid residue is preferred. And in order to improve the grade of the bleed-out accompanying heat processing, it is more preferable to contain an aliphatic polybasic acid and / or an aromatic polybasic acid having at least 4 carbon atoms. Moreover, as a glycol, it is preferable that it is a C2-C12 aliphatic or alicyclic glycol residue, and a C6-C12 aromatic glycol residue. These may be appropriately selected and used according to the desired retardation, and may contain only one type or two or more types. For example, when it is desired to produce a film with reduced retardation, it is preferable to select an aliphatic or alicyclic dicarboxylic acid residue or phthalic acid residue, and an aliphatic or alicyclic glycol residue. In addition, when it is desired to produce a film with an increased retardation, it is preferable to contain an aromatic dicarboxylic acid residue and / or an aromatic glycol residue.
Hereinafter, dibasic acids and glycols that can be preferably used for the synthesis of a condensate of a polyhydric alcohol and a polybasic acid will be described.

As the dibasic acid, either an aliphatic dicarboxylic acid or an aromatic dicarboxylic acid can be used.
Examples of the aliphatic dicarboxylic acid include oxalic acid, malonic acid, succinic acid, maleic acid, fumaric acid, glutaric acid, adipic acid, suberic acid, azelaic acid, cyclohexanedicarboxylic acid, sebacic acid, and dodecanedicarboxylic acid. . Of these, malonic acid, succinic acid and adipic acid are preferably included from the viewpoint of improving compatibility.
Examples of the aromatic dicarboxylic acid include phthalic acid, terephthalic acid, isophthalic acid, 1,5-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and the like. Of these, phthalic acid and terephthalic acid are preferable, and terephthalic acid is particularly preferable.
The number of carbon atoms of the dibasic acid is preferably 3-12, more preferably 4-8, and preferably 4-6. In the present invention, a mixture of two or more dibasic acids may be used. In this case, the average carbon number of the two or more dibasic acids is preferably in the above range. If the carbon number of the dibasic acid is within the above range, in addition to improving the luminance unevenness, it has excellent compatibility with the polymer constituting the second film and the third film, and when the second film and the third film are formed. Further, it is preferable because bleed-out hardly occurs even during heating and stretching.
It is also preferable to use an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid in combination. Specifically, a combination of adipic acid and phthalic acid, a combination of adipic acid and terephthalic acid, a combined use of succinic acid and phthalic acid, and a combined use of succinic acid and terephthalic acid are preferred. The combined use of succinic acid and terephthalic acid is more preferable. When the aliphatic dicarboxylic acid and the aromatic dicarboxylic acid are used in combination, the ratio (molar ratio) between the two is not particularly limited, but is preferably 95: 5 to 40:60, and more preferably 55:45 to 45:55.

Examples of the glycol (diol) include aliphatic diols and aromatic diols, and aliphatic diols are preferable.
The aliphatic diol is at least one of ethylene glycol, 1,2-propanediol, and 1,3-propanediol, and particularly preferably at least one of ethylene glycol and 1,2-propanediol. When two types are used, it is preferable to use ethylene glycol and 1,2-propanediol.
The number of carbon atoms of the glycol is preferably 2 to 10, more preferably 2 to 6, and particularly preferably 2 to 4. When using 2 or more types of glycol, it is preferable that 2 or more types of average carbon number becomes the said range. If the number of carbon atoms in the glycol is in the above range, in addition to improving luminance unevenness, it has excellent compatibility with the polymers constituting the second film and the third film, and bleeds out during film formation and heat stretching. This is preferable because

  Moreover, it is preferable to protect both ends of the condensate of polyhydric alcohol and polybasic acid with a monoalcohol residue or a monocarboxylic acid residue. In that case, the monoalcohol residue is preferably a substituted or unsubstituted monoalcohol residue having 1 to 30 carbon atoms.

  Moreover, when sealing with a monocarboxylic acid residue, the monocarboxylic acid used as a monocarboxylic acid residue is preferably a substituted or unsubstituted monocarboxylic acid having 1 to 30 carbon atoms. These may be aliphatic monocarboxylic acids or aromatic carboxylic acids. First, preferred aliphatic monocarboxylic acids are described. Examples include acetic acid, propionic acid, butanoic acid, caprylic acid, caproic acid, decanoic acid, dodecanoic acid, stearic acid, and oleic acid. Examples of aromatic monocarboxylic acids include benzoic acid. Acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid, etc. It can be used as a mixture of seeds or more.

  At this time, if the number of carbon atoms of the monocarboxylic acid residues at both ends is 3 or less, the volatility decreases, the weight loss due to heating of the condensate of polyhydric alcohol and polybasic acid does not increase, and process contamination Occurrence and occurrence of sheet failure can be reduced. From such a viewpoint, aliphatic monocarboxylic acids are preferable as monocarboxylic acids used for sealing. The monocarboxylic acid is more preferably an aliphatic monocarboxylic acid having 2 to 22 carbon atoms, more preferably an aliphatic monocarboxylic acid having 2 to 3 carbon atoms, and an aliphatic monocarboxylic acid residue having 2 carbon atoms. Particularly preferred is a group. For example, acetic acid, propionic acid, butanoic acid, benzoic acid and derivatives thereof are preferable, acetic acid or propionic acid is more preferable, and acetic acid (terminal is an acetyl group) is most preferable. Two or more monocarboxylic acids used for sealing may be mixed.

  In addition, when the both ends of the condensate of a polyhydric alcohol and a polybasic acid are unsealed, it is preferable that a condensate is a polyester polyol.

  The synthesis of a condensate of such a polyhydric alcohol and a polybasic acid is carried out by a conventional method, a hot melt condensation method using a (poly) esterification reaction or a transesterification reaction between the dibasic acid or an alkyl ester thereof and a glycol. Alternatively, it can be easily synthesized by any of the interfacial condensation methods of acid chlorides of these acids and glycols. Condensation products of these polyhydric alcohols and polybasic acids are described in detail in Koichi Murai, “Plasticizers, Theory and Applications” (Kokai Shobo Co., Ltd., first published on March 1, 1973). There is. In addition, Japanese Patent Laid-Open Nos. 05-155809, 05-155810, Japanese Patent Laid-Open Nos. 05-97073, 2006-259494, 07-330670, 2006-342227, 2007-003679. The materials described in each publication can also be used.

  Moreover, as a product, Adeka Sizer (various types of Adeka Sizer P series and Adeka Sizer PN series) described in DIARY 2007, pages 55 to 27 as a condensate of polyhydric alcohol and polybasic acid from ADEKA Co., Ltd. Dainippon Ink and Chemicals Co., Ltd. “Polymer-related products list 2007 edition” on page 25, various products of polylite, Dainippon Ink and Chemicals Co., Ltd. “DIC polymer modifier” (2004. 4) .1.000VIII issue) Various polycizers described on pages 2 to 5 can be used. Furthermore, it can be obtained as a Plasticall P series manufactured by CP HALL, USA. Benzoyl functionalized polyethers are commercially available from Velsicol Chemicals, Rosemont, Ill. Under the trade name BENZOFLEX (eg, BENZOFLEX 400, polypropylene glycol dibenzoate).

--- Condensate of polyhydric ether alcohol and polybasic acid ---
Next, the condensate of polyhydric ether alcohol and polybasic acid will be described. The condensate of polyhydric ether alcohol and polybasic acid refers to a condensation polymer of dicarboxylic acid and polyether diol. As the dicarboxylic acid, an aliphatic dicarboxylic acid residue having 4 to 12 carbon atoms or an aromatic dicarboxylic acid residue having 8 to 12 carbon atoms described as a condensate of a polyhydric alcohol and a polybasic acid is used as it is. is there.
In order to suppress contamination of the casting support, in the condensate of polyhydric ether alcohol and polybasic acid, at least one of the carbon atoms adjacent to the hydroxyl group of polyhydric ether alcohol is secondary carbon or tertiary carbon. Preferably there is.

Next, examples of the polyethers having an aliphatic glycol having 2 to 12 carbon atoms include polyethylene ether glycol, polypropylene ether glycol, polytetramethylene ether glycol, and combinations thereof. Typically useful commercially available polyether glycols include Carbowax resin, Pluronics resin and Niax resin. In the production of the polyester polyether plasticizer used in the present invention, a commonly used polymerization method known to those skilled in the art can be used.

  Examples of condensates of these polyhydric ether alcohols and polybasic acids include condensates of polyhydric ether alcohols and polybasic acids described in US Pat. No. 4,349,469.

--- Condensate of polyhydric alcohol and polybasic acid and isocyanate compound ---
Furthermore, a condensate of polyhydric alcohol and polybasic acid and an isocyanate compound will be described. The condensate can be obtained by the condensation of a polyhydric alcohol and polybasic acid condensate and an isocyanate compound. First, as the condensate of polyhydric alcohol and polybasic acid, the condensate of polyhydric alcohol and polybasic acid before sealing both ends can be used as it is, the condensation of polyhydric alcohol and polybasic acid. The above-mentioned materials can be preferably used.

Examples of the diisocyanate component forming the polyurethane structure include OCN (CH ₂ ) _p NCO (p = 2) represented by ethylene diisocyanate, trimethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate and the like. -8) Polymethylene isocyanate, and aromatic diisocyanates such as para-phenylene diisocyanate, tolylene diisocyanate, 4,4'-diphenylmethane diisocyanate, 1,5-naphthylene diisocyanate, Meta-xylylene diisocyanate and the like are used, but are not limited thereto. Among these, tolylene diisocyanate, meta-xylylene diisocyanate, and tetramethylene diisocyanate are particularly preferable.

  Regarding the synthesis of a condensate of a polyhydric alcohol and a polybasic acid and an isocyanate compound, JP-A Nos. 5-97073, 2001-122979, JP-A Nos. 2004-175971, and 2004-175972 are disclosed. The materials described in each publication can be used.

-Other additives-
The second film and the third film are not only the plasticizer described above, but also an ultraviolet absorber, a humidity dependence reducing agent, a compound having a hydroxyl group, a compound having an amino group, a compound that improves the durability of retardation, a polarizer Other additives such as a compound for improving durability and inorganic fine particles may be contained.
Various other additives (for example, deterioration preventing agents, release agents, infrared absorbers, wavelength dispersion adjusting agents, etc.) can be added to the second film and the third film, and they may be solid or oily. But you can. That is, the melting point and boiling point are not particularly limited. For example, mixing of ultraviolet absorbing material at 20 ° C. or lower and 20 ° C. or higher, and similarly mixing of a plasticizer is described in, for example, JP-A-2001-151901. Furthermore, infrared absorbing dyes are described in, for example, JP-A No. 2001-194522. Moreover, the addition time may be added at any time in the dope preparation step, but may be added by adding an additive to the final preparation step of the dope preparation step. Furthermore, the amount of each material added is not particularly limited as long as the function is manifested. Moreover, when a 2nd film and a 3rd film are formed from a multilayer, the kind and addition amount of the additive of each layer may differ. For example, it is described in Japanese Patent Application Laid-Open No. 2001-151902, and these are conventionally known techniques. For these details, materials described in detail on pages 16 to 22 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical No. 2001-1745, published on March 15, 2001, Japan Institute of Invention) are preferably used.
In addition, as other additives, additives usually used in cellulose esters (for example, the Japan Institute of Invention and Innovation Technical Report 2001-1745) can be used, and it is a compound having a repeating unit as described above. This is preferable from the viewpoint of suppression of bleeding out and suppression of volatilization in the film production process.

-UV absorber-
The ultraviolet absorber will be described.
The second film and the third film may contain two or more kinds of ultraviolet absorbers.
The two or more kinds of ultraviolet absorbers are preferably compounds not containing a halogen element, and more preferably represented by the following general formula (11).
Formula (11)

In general formula (11), X is a hydrogen atom, an alkyl group, an alkoxyl group, a hydroxyl group, an amino group, or an amide group. If possible, these may further have a substituent.
In at least one of the ultraviolet absorbers, Y and Z in the general formula (11) are each independently an alkyl group, the alkyl group represented by Y and Z does not contain an aromatic ring as a substituent,
In at least one of the ultraviolet absorbers, Y and Z in the general formula (11) are each independently an alkyl group, and the alkyl group represented by Y and Z has one aromatic ring as a substituent.

  X is preferably a hydrogen atom, an alkyl group, an alkoxyl group, or a hydroxyl group.

  In General Formula (11), X preferably represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms, and more preferably a hydrogen atom.

  Examples of the alkyl group having 1 to 5 carbon atoms include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, an isopropyl group, a tert-butyl group, an isobutyl group, and a sec-butyl group.

  Examples of the alkoxy group having 1 to 5 carbon atoms include methoxy group, ethoxy group, propoxy group, butoxy group, pentyloxy group, isopropoxy group, tert-butoxy group, isobutoxy group, sec-butoxy group and the like. .

When the second film and the third film contain two or more kinds of ultraviolet absorbers, at least one of the ultraviolet absorbers is such that Y and Z in the general formula (11) are each independently an alkyl group, and Y and Z It is preferable that the alkyl group represented by does not contain an aromatic ring as a substituent, and at least one of the ultraviolet absorbers is an alkyl represented by Y and Z in which Y and Z in General Formula (11) are each independently an alkyl group. It is preferred that the group has one aromatic ring as a substituent.
In the general formula (11), Y and Z are each independently an alkyl group, the alkyl group represented by Y and Z does not contain an aromatic ring as a substituent, and Y and Z in the general formula (11) are respectively In combination with an ultraviolet absorber that is independently an alkyl group and the alkyl group represented by Y and Z has one aromatic ring as a substituent, the effect of suppressing the whitening phenomenon during saponification is obtained. . As the aromatic ring, a benzene ring is preferable.

  Y and Z in the general formula (11) each preferably represent a substituted or unsubstituted alkyl group having 2 to 20 carbon atoms.

  The substituted or unsubstituted alkyl group having 2 to 20 carbon atoms may be linear or branched, and may have a substituent. Examples of the substituted or unsubstituted alkyl group having 2 to 20 carbon atoms include an ethyl group, an isopropyl group, a tert-butyl group, a tert-amyl group, a tert-octyl group, a hydroxyethyl group, a methoxymethyl group, and a butoxyethyl group. Is mentioned.

  In the general formula (1), Y and Z are each independently an alkyl group, the alkyl group represented by Y and Z does not contain an aromatic ring as a substituent, and Y and Z in the general formula (1) are respectively The content ratio with the ultraviolet absorber which is independently an alkyl group and the alkyl group represented by Y and Z has one aromatic ring as a substituent is preferably 95: 5 to 10:90, and 80:20 to 50: 50 is more preferable.

  From the viewpoint of spectral transmittance, the total addition amount of the ultraviolet absorber is preferably 0.5 parts by mass or more and 10 parts by mass or less, and more preferably 1 part by mass or more and 5 parts by mass or less with respect to 100 parts by mass of cellulose acylate. preferable.

-Humidity dependency reducing agent-
The second film and the third film may further contain a humidity dependence reducing agent having ΔRth (A) defined by the following formula (A) of −100 or more and less than 0 nm as a compound that further reduces the humidity dependence. it can. When such an additive is used in combination, the humidity dependency of Rth can be more efficiently reduced, so that the total amount of the additive can also be reduced. Therefore, it is preferable from the viewpoint of suppressing contamination of the casting support.
Formula (A) ΔRth (A) = (ΔRth (rh, A) −ΔRth (rh, 0)) / Q
[In the formula, ΔRth (rh, A) represents a value obtained by subtracting Rth at 25 ° C. and 80% relative humidity from Rth at 25 ° C. and relative humidity of 10% of the film to which the compound was added, and ΔRth (rh, 0 ) Represents a value obtained by subtracting Rth at 25 ° C./80% relative humidity from Rth at 25 ° C./10% relative humidity of the film to which no compound is added, and Q represents the second and third films in the film. This represents the mass of the compound when the mass of the constituting polymer is 100. ]

-Compound having a hydroxyl group-
Examples of the compound containing a hydroxyl group that is preferably used as a humidity dependence reducing agent, more preferably a compound containing a phenolic hydroxyl group, include, for example, Compound A described in JP-A-2008-89860, pages 13 to 19, and A compound represented by the general formula (I) described in pages 7 to 9 of Kaikai 2008-233530 can be preferably used.

-Compound having an amino group-
The compound etc. which are indicated by JP, 2012-198529, A can be used conveniently.

-Compounds that improve the durability of retardation-
The compound etc. which are indicated by JP, 2013-20223, A can be used conveniently.

-Compounds that improve the durability of polarizers (polarizer durability improvers)-
The polarizer durability improving agent preferably has a hydrogen bonding hydrogen donating group.

Examples of hydrogen bonding hydrogen donating groups are described, for example, in Jeffrey, George A., et al. It is described in a book such as Introduction to Hydrogen Bonding published by Oxford UP.
As the hydrogen bondable hydrogen donating group in the polarizer durability improving agent, from the viewpoint of interaction with the carbonyl group in cellulose acylate, an amino group, an acylamino group, an alkoxycarbonylamino group, an aryloxycarbonylamino group, A sulfonylamino group, a hydroxy group, a mercapto group, and a carboxyl group are preferable, a sulfonylamino group, an acylamino group, an amino group, and a hydroxyl group are more preferable, and an amino group and a hydroxyl group are still more preferable.

The ratio of molecular weight / aromatic ring number in the polarizer durability improving agent is preferably 300 or less, more preferably 190 or less, particularly preferably 160 or less, and particularly preferably 150 or less.
The ratio of molecular weight / aromatic ring number in the polarizer durability improving agent is preferably 90 or more, and more preferably 100 or more, from the viewpoint of improving compatibility with cellulose acylate.

The molecular weight of the polarizer durability improving agent is preferably 200 to 1000, more preferably 250 to 800, and particularly preferably 280 to 600. When the molecular weight is equal to or higher than the lower limit of the above range, disappearance due to volatilization of the polarizer durability improver during film formation of the cellulose acylate film can be suppressed, and when the molecular weight is equal to or lower than the upper limit of the above range, cellulose acylate And a polarizer durability improving agent are preferable because a cellulose acylate film having good compatibility and a low haze can be obtained.
Hereinafter, the polarizer durability improving agent will be described in the order of the compound represented by the general formula (1) and the compound represented by the general formula (2).

--Compound represented by the general formula (1)-

In General Formula (1), R ¹ represents a substituent, R ² represents a substituent represented by the following General Formula (1-2); n1 represents an integer of 0 to 4, and n1 is 2 or more. A plurality of R ¹ may be the same or different; and n2 represents an integer of 1 to 5, and when n2 is 2 or more, a plurality of R ² may be the same or different from each other. Also good.

In general formula (1-2), A represents a substituted or unsubstituted aromatic ring; R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or the following general formula: Represents a substituent represented by (1-3); R ⁵ represents a single bond or an alkylene group having 1 to 5 carbon atoms; X represents a substituted or unsubstituted aromatic ring; and n3 represents 0. Represents an integer of -10, and when n3 is 2 or more, the plurality of R ⁵ and X may be the same or different from each other.

In General Formula (1-3), X represents a substituted or unsubstituted aromatic ring; R ⁶ , R ⁷ , R ⁸ , and R ⁹ are each independently a hydrogen atom or a C 1-5 carbon atom. N5 represents an integer of 1 to 11, and when n5 is 2 or more, a plurality of R ⁶ , R ⁷ , R ⁸ , R ⁹ and X may be the same or different.

R ¹ represents a substituent. Examples of the substituent are not particularly limited, and may be an alkyl group (preferably an alkyl group having 1 to 10 carbon atoms such as methyl, ethyl, isopropyl, t-butyl, pentyl, heptyl, 1-ethylpentyl, benzyl, 2 -Ethoxyethyl, 1-carboxymethyl, etc.), alkenyl groups (preferably alkenyl groups having 2-20 carbon atoms, such as vinyl, allyl, oleyl, etc.), alkynyl groups (preferably alkynyl groups having 2-20 carbon atoms). , For example, ethynyl, butadiynyl, phenylethynyl, etc.), a cycloalkyl group (preferably a cycloalkyl group having 3 to 20 carbon atoms, such as cyclopropyl, cyclopentyl, cyclohexyl, 4-methylcyclohexyl, etc.), an aryl group (preferably An aryl group having 6 to 26 carbon atoms, such as phenyl, -Naphthyl, 4-methoxyphenyl, 2-chlorophenyl, 3-methylphenyl and the like), a heterocyclic group (preferably a heterocyclic group having 2 to 20 carbon atoms, such as 2-pyridyl, 4-pyridyl, 2-imidazolyl, 2-benzimidazolyl, 2-thiazolyl, 2-oxazolyl, etc.), an alkoxy group (preferably an alkoxy group having 1 to 20 carbon atoms, such as methoxy, ethoxy, isopropyloxy, benzyloxy, etc.), an aryloxy group (preferably carbon An aryloxy group having 6 to 26 atoms such as phenoxy, 1-naphthyloxy, 3-methylphenoxy, 4-methoxyphenoxy, etc., an alkoxycarbonyl group (preferably an alkoxycarbonyl group having 2 to 20 carbon atoms, such as Ethoxycarbonyl, 2-ethylhexyloxycar Nyl, etc.), an amino group (preferably an amino group having 0 to 20 carbon atoms, such as amino, N, N-dimethylamino, N, N-diethylamino, N-ethylamino, anilino, etc.), a sulfonamide group (preferably Is a sulfonamide group having 0 to 20 carbon atoms, such as N, N-dimethylsulfonamide, N-phenylsulfonamide, etc., an acyloxy group (preferably an acyloxy group having 1 to 20 carbon atoms, such as acetyloxy, Benzoyloxy and the like), a carbamoyl group (preferably a carbamoyl group having 1 to 20 carbon atoms, such as N, N-dimethylcarbamoyl, N-phenylcarbamoyl and the like), an acylamino group (preferably an acylamino group having 1 to 20 carbon atoms) For example, acetylamino, benzoylamino, etc.), cyano group, or halogen atom (For example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.) and a hydroxyl group are mentioned.

R ¹ is preferably an alkyl group having 1 to 20 carbon atoms and a hydroxyl group, more preferably a hydroxyl group and a methyl group. R ¹ may further have one or more substituents, and examples of the further substituent include the same substituents as R ¹ .

  n1 represents the integer of 0-4, and 2-4 are preferable.

  n2 represents the integer of 1-5, 1-3 are preferable and 1-2 are more preferable.

R ² represents a substituent represented by the following general formula (1-2).

In general formula (1-2), A represents a substituted or unsubstituted aromatic ring; R ³ and R ⁴ each independently represent a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or the following general formula: Represents a substituent represented by (1-3); R ⁵ represents a single bond or an alkylene group having 1 to 5 carbon atoms; X represents a substituted or unsubstituted aromatic ring; and n3 represents 0. Represents an integer of -10, and when n3 is 2 or more, the plurality of R ⁵ and X may be the same or different from each other.

A represents a substituted or unsubstituted aromatic ring. The aromatic ring may be a heterocyclic ring containing a hetero atom such as a nitrogen atom, an oxygen atom, or a sulfur atom. Examples of A include benzene ring, indene ring, naphthalene ring, fluorene ring, phenanthrene ring, anthracene ring, biphenyl ring, pyrene ring, pyran ring, dioxane ring, dithiane ring, thiyne ring, pyridine ring, piperidine ring, oxazine ring Morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperazine ring, triazine ring and the like. Further, other 6-membered rings or 5-membered rings may be condensed.
A is preferably a benzene ring.
Examples of the substituent that A may have include a halogen atom (for example, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, etc.), an alkyl group, a hydroxyl group, and the like. An alkyl group or a hydroxyl group is preferable, and carbon A C1-C10 alkyl group or a hydroxyl group is more preferable, and a C1-C5 alkyl group or a hydroxyl group is still more preferable.

In General Formula (1-2), R ⁵ represents a single bond or an alkylene group having 1 to 5 carbon atoms, and the alkylene group having 1 to 5 carbon atoms may have a substituent. R ⁵ is preferably an alkylene group having 1 to 4 carbon atoms, and more preferably an alkylene group having 1 to 3 carbon atoms. Examples of the substituent that R ⁵ may have include an alkyl group having 1 to 5 carbon atoms (eg, methyl, ethyl, isopropyl, t-butyl), a halogen atom (eg, fluorine atom, chlorine atom, bromine atom, iodine). Atoms), hydroxyl groups and the like.

  In general formula (1-2), X represents a substituted or unsubstituted aromatic ring. The aromatic ring may be a heterocyclic ring containing a hetero atom such as a nitrogen atom, an oxygen atom, or a sulfur atom. Examples of X include benzene ring, indene ring, naphthalene ring, fluorene ring, phenanthrene ring, anthracene ring, biphenyl ring, pyrene ring, pyran ring, dioxane ring, dithiane ring, thiyne ring, pyridine ring, piperidine ring, oxazine ring Morpholine ring, thiazine ring, pyridazine ring, pyrimidine ring, pyrazine ring, piperazine ring, triazine ring and the like. Further, other 6-membered rings or 5-membered rings may be condensed. X is preferably a benzene ring. Examples of the substituent which X may have are the same as the examples given as the substituent of A.

n3 represents the integer of 0-10, 0-2 are preferable and 0-1 are more preferable. When n3 is an integer of 2 or more, a plurality of groups represented by — (R ⁵ —X) may be the same as or different from each other, and each bond to A. When n3 is 0, a group represented by — (R ⁵ —X) does not exist, and thus a group represented by — (R ⁵ —X) is not bonded to A.

R ³ and R ⁴ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms and a substituent represented by the following general formula (1-3). R ³ and R ⁴ are preferably a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, or a substituent represented by the general formula (1-3), and a hydrogen atom, a methyl group, or a general formula (1-3) The substituent represented is more preferred.

In the substituent represented by the general formula (1-3) that may be contained in the substituent represented by the general formula (1-2), X represents a substituted or unsubstituted aromatic ring; R ⁶ , R ⁷ , R ⁸ and R ⁹ each independently represents a hydrogen atom or an alkyl group having 1 to 5 carbon atoms;
Represents an integer of 11, and when n5 is 2 or more, a plurality of R ⁶ , R ⁷ , R ⁸ , R ⁹ and X may be the same or different from each other.

X in the substituent represented by the general formula (1-3) which may be contained in the substituent represented by the general formula (1-2) has the same meaning as X in the general formula (1-2). The preferred range is also the same.
R ⁶ , R ⁷ , R ⁸ , and R ⁹ each independently represent a hydrogen atom or an alkyl group having 1 to 5 carbon atoms. R ³ and R ⁴ are preferably a hydrogen atom or an alkyl group having 1 to 3 carbon atoms, more preferably a hydrogen atom or a methyl group.

  n5 represents an integer of 1 to 11, preferably 1 to 9, and more preferably 1 to 7.

  The substituent represented by the general formula (1-3) that may be contained in the substituent represented by the general formula (1-2) is a substituent represented by the following general formula (1-3 ′). It is preferable that

  The definition of each symbol of the general formula (1-3 ′) that may be included in the substituent represented by the general formula (1-2) is the same as that in the general formula (1-3). The preferable range is also the same.

  The substituent represented by the general formula (1-3) that may be contained in the substituent represented by the general formula (1-2) is a substituent represented by the following general formula (1-3 ″). More preferably, it is a group.

  In general formula (1-3 ″), n4 represents an integer of 0 to 10.

  n4 represents the integer of 0-10, 0-8 are preferable and 0-6 are more preferable.

  The substituent represented by the general formula (1-2) is preferably a substituent represented by the following general formula (1-2 ').

In General Formula (1-2 ′), R ³ represents a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, or a substituent represented by General Formula (1-3); R ⁵ represents a single bond or Represents an alkylene group having 1 to 5 carbon atoms; X represents a substituted or unsubstituted aromatic ring; n3 represents an integer of 0 to 5; and when n3 is 2 or more, a plurality of R ⁵ and X are They may be the same or different.

  The preferred range of each symbol in the general formula (1-2 ') is the same as that in the general formula (1-2).

  The general formula (1-2) is preferably represented by the following general formula (1-2 ″).

In general formula (1-2 ″), n3 represents an integer of 0 to 5.
The preferable range of n3 in the general formula (1-2 ″) is the same as the preferable range of n3 in the general formula (1-2).

  Although the specific example of a compound represented by General formula (1) below is shown, it is not limited to the following specific examples.

  In addition, in order to enable the compound represented by the general formula (1) having a different number of hydroxyl groups to be hydrogen-bonded at multiple points, it contains two or more different compounds represented by the general formula (1). It is good also as a mixture. One example is a styrenated phenol in which 1 to 3 moles of styrene are alkylated with respect to phenol, a styrenated phenol in which styrene is further alkylated at the phenyl moiety of the alkylated styrene, and an oligomer of about 2 to 4 mers of styrene. Mention may be made of mixtures with styrenated phenols alkylated to phenol.

The compound represented by the general formula (1) can generally be synthesized by adding 1 equivalent or more of styrenes in the presence of an acid catalyst to 1 equivalent of phenols, and a commercially available product may be used. . Moreover, you may use the mixture obtained by the said synthesis method as it is.
As a commercial item of the compound represented by the general formula (1), “TSP” which is a styrenated phenol manufactured by Sanko Co., Ltd., “PH-25” manufactured by Nikko Paint Chemical Co., Ltd., “manufactured by Seiko Chemical Co., Ltd.” Non-flex WS "etc. are mentioned.

（一般式（２）中、Ｒ¹¹、Ｒ¹³及びＲ¹⁵は、各々独立に、水素原子、炭素数１〜２０のアルキル基、炭素数３〜２０のシクロアルキル基、炭素数２〜２０のアルケニル基または炭素数６〜２０の芳香族基を表す。） --Compound represented by formula (2)-

(In the general formula (2), R ¹¹ , R ¹³ and R ¹⁵ are each independently a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an alkyl group having 2 to 20 carbon atoms. Represents an alkenyl group or an aromatic group having 6 to 20 carbon atoms.)

In the general formula (2), R ¹⁵ preferably represents an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aromatic group having 6 to 20 carbon atoms, and 1 to 12 carbon atoms. It is more preferable that it is a C3-C12 cycloalkyl group or a C6-C18 aromatic group, and a C1-C6 alkyl group and a C3-C6 cycloalkyl group are also included. Or an aromatic group having 6 to 12 carbon atoms, more preferably a methyl group, an ethyl group, an isopropyl group, a cyclohexyl group or a phenyl group, and a methyl group, an isopropyl group or a phenyl group. Most preferred.

In general formula (2), R ¹¹ and R ¹³ are each independently preferably a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, or an aromatic group having 6 to 20 carbon atoms. It is more preferably an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aryl group having 6 to 12 carbon atoms, a hydrogen atom, an alkyl group having 1 to 6 carbon atoms, and a carbon atom having 3 to 6 carbon atoms. It is particularly preferably a cycloalkyl group or a phenyl group, more preferably a hydrogen atom, a methyl group, an ethyl group, a cyclohexyl group or a phenyl group, and most preferably a methyl group or a phenyl group.
In General Formula (2), R ¹¹ is an alkyl group having 1 to 20 carbon atoms, a cycloalkyl group having 3 to 20 carbon atoms, or an aromatic group having 6 to 20 carbon atoms, and R ¹³ is a hydrogen atom. Or it is preferable that it is a C6-C20 aromatic group. R ¹¹ is an alkyl group having 1 to 12 carbon atoms, a cycloalkyl group having 3 to 12 carbon atoms, or an aromatic group having 6 to 12 carbon atoms, and R ¹³ is a hydrogen atom or an aromatic group having 6 to 12 carbon atoms. More preferably, it is a group. It is particularly preferable that R ¹¹ is an alkyl group having 1 to 3 carbon atoms or a cyclohexyl group, and R ¹³ is a hydrogen atom or a phenyl group. It is more particularly preferable that R ¹¹ is a methyl group and R ¹³ is a hydrogen atom or a phenyl group.

R ¹⁵ may further have a substituent. The substituent that R ¹⁵ may have is not particularly limited as long as it does not contradict the gist of the present invention, but is preferably a halogen atom, an alkyl group, or an aromatic group, and preferably a halogen atom, carbon number 1 It is more preferably an alkyl group having ˜6 or an aromatic group having 6 to 12 carbon atoms, particularly preferably a chlorine atom, a methyl group, or a phenyl group. In particular, when R ¹⁵ is an alkyl group having 1 to 20 carbon atoms, it preferably has an aromatic group as a substituent, more preferably an aromatic group having 6 to 12 carbon atoms, and a phenyl group. Is particularly preferred. In particular, when R ¹⁵ is an aromatic group having 1 to 20 carbon atoms, it preferably has a halogen atom or an alkyl group having 1 to 20 carbon atoms as a substituent, and a halogen atom or an alkyl group having 1 to 6 carbon atoms. It is more preferable to have a group, and it is particularly preferable to have a chlorine atom or a methyl group.

R ¹¹ and R ¹³ may further have a substituent. The substituent that R ¹¹ may have is not particularly limited as long as it does not contradict the gist of the present invention, but is preferably an aromatic group having 6 to 12 carbon atoms, more preferably a phenyl group. preferable.

  Although the specific example of a compound represented by General formula (2) below is shown, it is not limited to the following specific examples.

  The compound represented by the general formula (2) may be obtained commercially or synthesized by a known method.

-Content-
In the second film and the third film, the content of the compound represented by the general formula (1) or (2) is preferably 0.5% by mass to 20% by mass with respect to the cellulose acylate. More preferably, it is -20 mass%. If it is 1% by mass or more with respect to the cellulose acylate, an effect of improving the elastic modulus is easily obtained, and if it is 20% by mass or less with respect to the cellulose acylate, bleeding occurs when a cellulose acylate film is formed. Out and exudation hardly occur.
The content of the compound represented by the general formula (1) or (2) is particularly preferably 1 to 15% by mass, and more preferably 1 to 10% by mass with respect to the cellulose acylate.

  On the other hand, in order to improve the reworkability of the polarizing plate using the second film and the third film, it is preferable to impart a thickness direction distribution of the additive using, for example, a known co-casting technique. Specifically, it is preferable that the content of the additive near the surface is lower than the content of other portions.

-Inorganic fine particles (matting agent)-
It is preferable to add fine particles to the surface of the second film and the third film in order to impart slipping between the films and prevent blocking. As the fine particles, silica (silicon dioxide, SiO ₂ ) whose surface is coated with a hydrophobic group and takes the form of secondary particles is preferably used. The fine particles include, together with or in place of silica, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate, phosphoric acid Fine particles such as calcium may be used.

The inorganic fine particles function as a so-called matting agent, and by adding fine particles, minute irregularities are formed on the film surface, and even if the films overlap each other due to the irregularities, the films do not stick to each other, and the slipperiness between the films is ensured. In particular slipperiness when this time projection minute unevenness height 30nm or more protrusions due to fine particles protruding from the film surface is 104 pieces / mm ² or more per 1 mm ^2, a large effect of improving the blocking resistance.

In addition, when the second film and the third film are used as a protective film for a polarizing plate, it is preferable to saponify the film. At this time, the protrusion height on the film surface is low and the density is reduced, and the hydrophilic property is reduced. There is a tendency that sticking becomes easy by absorbing moisture and becoming easy to swell. Therefore, slip properties after it is saponification after saponification process is performed (saponified after) any projections fine unevenness height 30nm or more protrusions by the particles is projected has 104 pieces / mm ² or more per 1 mm ² Great effect in improving blocking properties.

  In particular, it is preferable to apply the inorganic fine particles to the surface layer in order to improve the blocking property and the slipping property without increasing the haze of the film. Examples of the method for imparting fine particles to the surface layer include means by multilayer casting or coating.

  When the contact surface pressure increases in the film roll, the overlapping portions of the film stick together with a certain probability and become difficult to slip. As described above, the phenomenon in which the overlapped films adhere to each other due to excessive pressure applied to the surface of the film is also called blocking. Since the films stick to each other and become difficult to slip, the deformation when the film is wound is not alleviated by the slip. Therefore, the conventional film roll has a failure (hereinafter referred to as the film deformation on the core side) due to the dents and wrinkles along the circumferential direction called beco, the irregularities of the core and the film end face (cut) at the time of winding. (Referred to as a core side photographic failure). This bevel, wrinkle, and core side shoot failure is more likely to occur as the film is thinner and the elastic modulus of the film is lower.

In the film roll, a contact surface pressure within a range of about 0.01 MPa or more and about 0.10 MPa or less is applied to a region portion (use portion) used for use between the knurling portions.
The contact surface pressure applied to the film portion in the vicinity of the winding core tends to increase as the film becomes longer. A contact surface pressure in the range of 0.05 MPa or more and 0.10 MPa or less is applied on the winding core side of a long film having a length of less than 4000 m. Therefore, conventionally, when the film is shorter than 2000 m, no major problem has occurred. However, when the film is long, for example, within the range of 2000 m or more and 10000 m or less, blocking, bevel, wrinkle, core side There was a tendency for image failures to occur.

  Also, conventionally, when the film is thin, for example, within a range of 10 μm or more and 60 μm or less, blocking, beveling, wrinkling, and core side image failure may occur when the film is wound around a core and used as a film roll. It was prone to occur. In addition, conventionally, when the elastic modulus of the film is low, for example, within a range of 1.0 GPa or more and 4.0 GPa or less, when the film is wound around a core to form a film roll, blocking, Wrinkles and core-side image failure are likely to occur.

  In order to improve the winding property, it is effective to improve the blocking property and slipping property by imparting fine irregularities on the film surface. In particular, when the contact surface pressure between the films is 0.05 MPa or more and 0.10 MPa, the coefficient of static friction is 1.2 or less, so that slip occurs between the overlapping parts of the film, so that blocking, bevel, wrinkle, core side The occurrence of image failure is reduced. It is preferable that the static friction coefficient of the portion in the contact surface pressure range of 0.05 MPa or more and 0.10 MPa or less is 1.0 or less, and the static friction coefficient of the portion in the range of contact surface pressure of 0.05 MPa or more and 0.10 MPa or less. Is more preferably 0.9 or less.

-Compounds controlling optical anisotropy-
It is preferable that the 2nd film and the 3rd film contain the compound which controls optical anisotropy, it is preferable that the total content rate is 13-70 mass%, 15-60 mass% is more preferable, 18- 50 mass% is more preferable. Among these, the ratio of the retardation increasing agent is preferably 0.01 to 10% by mass, more preferably 0.05 to 7% by mass, and further preferably 0.10 to 5% by mass. .

-Total content of additives (Ct)-
The total content (Ct) of the additive is preferably 5 to 200 phr, more preferably 10 to 100 phr, and still more preferably 15 to 60 phr. However, in some cases, the content of the additive is preferably 2 to 100 phr, more preferably 5 to 50 phr, and even more preferably 6 to 30 phr. The latter preferred embodiment can be preferably applied particularly to a thin film from the viewpoint of improving luminance unevenness. If the addition amount and film thickness satisfy such conditions, the luminance unevenness can be improved, and if it is 200 phr or less, bleed out from the film is easily suppressed. In the case of a thin film, since the bleed out from the film tends to be promoted, the upper limit of the addition amount is set lower.
In addition, when making it contain 2 or more types of additives, the total content of 2 or more types of additives should just fall in the said range in a 2nd film and a 3rd film.

-Surface content of additive (Cs)-
In the second film and the third film, the adhesiveness and light resistance of the functional layer are improved on the second film and the third film, or the reworkability of the polarizing plate using the second film and the third film is improved. Therefore, it is preferable to reduce the surface content of the additive. Accordingly, the surface content (Cs) of the additive is preferably lower than the total content (Ct) of the additive, and (Ct-Cs) is preferably 50 phr or less, more preferably 3 to 30 phr, and more preferably 5 to 20 phr. Is more preferable. When it is 50 phr or less, it is preferable because, for example, a fine wrinkle-like surface failure is unlikely to occur.
When a compound having a repeating unit is used as an additive, the additive amount distribution in the film thickness direction is less likely to be attached as compared with a low molecular compound that has been used as a plasticizer for a long time. Therefore, in order to achieve such a surface content, it is preferable to co-cast layers having different additive concentrations as described later.
The method for measuring the surface content is not particularly limited. For example, an ATR prism (for example, MKII Golden Gate Single Reflection ATR System, manufactured by Specac) made of Ge, KRS-5, diamond, ZnSe, or the like is used as a Fourier transform infrared spectrometer ( For example, it can be evaluated by mounting in a NICOLET 6700 (manufactured by Thermo Fisher), measuring in a reflection mode, and observing a characteristic absorption peak area. Specifically, it can be evaluated using the ratio (I ₂ / I ₁ ) between the absorption peak area (I ₁ ) derived from the polymer and the peak area (I ₂ ) derived from the additive.
It is also possible to cut a sample up to 3 μm from the film surface and measure the obtained sample in the transmission mode of a Fourier transform infrared spectrometer. When using the sample cut in this way, it is measured by using a nuclear magnetic resonance absorber ( ¹ H-NMR, for example, AVANCE400, manufactured by Bruker), and evaluated by observing a characteristic signal intensity ratio. You can also.

(Method for producing second film and third film)
The method for producing the second film and the third film preferably has at least the following steps (a), (b), and (c).
(A) Step of casting a solution containing one kind of polymer and solvent on a support (b) Step of peeling off from the support (c) Step of stretching in the transport direction

The step (c) will be described first.
The stretching is preferably performed in a state where the residual solvent amount is 1.0 to 300% by mass from the viewpoint of improving the reworkability of the polarizing plate using the second film and the third film, and the residual solvent amount is 100 to 280. The mass% is more preferable, and 150 to 250 mass% is still more preferable.

The draw ratio in the transport direction can be appropriately set according to the characteristics required for the second film and the third film, preferably 1 to 500%, more preferably 3 to 100%, and still more preferably 5 to 80%. 10 to 60% is particularly preferable. These stretching operations may be performed in one stage or in multiple stages. In addition, "stretch ratio (%)" means what was calculated | required using the following formula | equation.
Stretch ratio (%) = 100 × {(Length after stretching) − (Length before stretching)} / Length before stretching Here, the length before stretching and the length after stretching are the stretching zone. It can also be evaluated as the transport speed of the base before and the transport speed of the base after the stretching zone.
On the other hand, when producing the second film and the third film, it is not possible to stretch in the direction orthogonal to the conveying direction as much as possible, and the elasticity in the direction parallel to the absorption axis of the first film of the second film and the third film. From the viewpoint of controlling the rate and humidity dimensional change rate within a preferable range. The draw ratio in the direction orthogonal to the transport direction is preferably suppressed to such an extent that it is naturally applied when transporting while maintaining the film width (for example, pin width), for example, 0 to 5% is preferable, and 0 to 3%. Is more preferable, 0 to 1% is particularly preferable, and when the film spontaneously contracts, it is preferable to contract, for example, −30 to 0% is preferable, −20 to −3% is more preferable, and −15 -5% is particularly preferred.

  The stretching speed in stretching in the transport direction is preferably 10 to 10000% / min, more preferably 100 to 3000% / min, and further preferably 200 to 1500% / min.

It is preferable from the viewpoint of reducing the value X, the value x, the value Y, and the value y to have a heat treatment (post heat treatment) step after the stretching step. The temperature of the post heat treatment is (Tg-10) ° C. or higher (Tg + 60) ° C. when the glass transition temperature of the optical film is Tg (unit: ° C.) from the viewpoint of reducing the residual strain accumulated in the film in a short time. It is preferable that it is less than, Tg- (Tg + 50) degreeC is more preferable, (Tg + 10) degreeC- (Tg + 40) degreeC is further more preferable. (Tg−10) ° C. or higher is preferable from the viewpoint of productivity because the heat treatment time necessary for sufficiently reducing residual strain is shortened, and (Tg + 60) ° C. or lower is preferable because retardation shift is suppressed. . The heat treatment time is not particularly limited as long as it is sufficient to reduce residual strain, but is preferably 0.01 to 60 minutes, and preferably 0.1 to 40 minutes. Is more preferable, and it is still more preferable that it is for 1 to 30 minutes. If it is 0.01 minutes or more, it is preferable because residual strain can be sufficiently reduced, and if it is 60 minutes or less, productivity can be secured.
Hereinafter, the manufacturing method of a 2nd film and a 3rd film is demonstrated including the process of (a) and the process of (b).

-Organic solvent of dope solution-
Chlorinated halogenated hydrocarbons may be used as the main solvent for the second film and the third film, and as described in JIII Journal of Technical Disclosure 2001-1745 (pages 12-16), A chlorinated solvent may be used as the main solvent, and the second film and the third film are not particularly limited.

  In addition, the solvent about a dope solution and a 2nd film and a 3rd film is disclosed by the following patents including the melt | dissolution method, and is a preferable aspect. They are, for example, JP 2000-95876, JP 12-95877, JP 10-324774, JP 8-152514, JP 10-330538, JP 9-95538, JP 9-95557, JP 10-10. -235664, JP-A-12-63534, JP-A-11-21379, JP-A-10-182853, JP-A-10-278056, JP-A-10-279702, JP-A-10-323853, JP-A-10-237186, JP-A-11-60807. JP-A-11-152342, JP-A-11-292988, JP-A-11-60752, JP-A-11-60752, and the like. According to these patents, not only the preferred solvent for the cellulose ester preferably used in the present invention but also the physical properties of the solution and coexisting substances to be coexisted are described, which is also a preferred embodiment in the present invention.

-Dissolution process-
Preparation of the dope solution is not particularly limited, and it may be performed at room temperature, and further, a cooling dissolution method or a high temperature dissolution method, and further a combination thereof. Regarding the preparation of the dope solution according to the present invention, and further the solution concentration and filtration steps involved in the dissolution step, the Technical Report of the Invention Association (Public Technical Number 2001-1745, published on March 15, 2001, Invention Association) Production processes described in detail on pages 22 to 25 are preferably used.

-Casting, drying, stretching, winding process-
Next, a method for producing the second film and the third film using the dope solution will be described. As a method and equipment for producing the second film and the third film, a solution casting film forming method and a solution casting film forming apparatus conventionally used for producing a cellulose triacetate film can be used. It is preferable that the dope solution prepared from the dissolving machine (kettle) is temporarily stored in a storage kettle, and the foam contained in the dope is defoamed for final preparation. The dope is sent from the dope discharge port to the pressure die through a pressure metering gear pump capable of delivering a constant amount of liquid with high accuracy, for example, by the number of rotations. It is preferable to peel off the raw dry dope film (also referred to as web) from the metal support at a peeling point which is uniformly cast on the metal support and the metal support has made one round.
Both ends of the obtained web are clipped, conveyed by a tenter while holding the width and dried, and then the obtained film is mechanically conveyed by a roll group in a heating device and rolled into a predetermined shape by a winder. It is preferable to wind up to the length. When transporting with a tenter (for example, a pin tenter), it is preferable not to stretch the second film and the third film in a direction orthogonal to the transport direction as much as possible, for example, while maintaining the film width (for example, pin width). It is preferable to carry. The combination of the tenter and the roll group dryer varies depending on the purpose. As another embodiment, the metal support described above is a drum cooled to 5 ° C. or less, and after the dope extruded from the die is gelled on the drum, it is peeled off after about one turn and is held by a pin-shaped tenter. It is manufactured by a solvent cast method, such as a method in which the film obtained is transported and dried, and then the obtained film is mechanically transported by a group of rolls in a heating device and wound up to a predetermined length by a winder. Various methods of filming can be taken. From the viewpoint of reducing the film shrinkage force, a step of once cooling the dope and transporting the dope to a high-temperature drying zone with a large amount of residual solvent is preferred, and a cooling casting method using a cooled drum is preferred. In the present invention, the zone between the separation from the metal support and before gripping with the tenter can be preferably used as the stretching step, and by making a difference between the rotation speed of the metal support and the transport speed of the tenter. The web can be stretched, and preferred stretch ratios are as described above.
A zone that is mechanically conveyed by a group of rolls in a heating device can be preferably used as a post-heat treatment step, and the tension during conveyance is preferably low, preferably 10 to 300 N, and more preferably 15 to 200 N. Preferably, it is 20-150N. The conveyance tension can be controlled by adding a peripheral speed difference between the rolls in the heating device, and if it is 10 N or more, it prevents slipping between the film and the roll and prevents the film from being scratched. Preferably, if it is 300 N or less, the residual distortion of the film can be effectively reduced, which is preferable. Further, when the conveyance tension is lowered, residual strain is less likely to accumulate, and the values X, x, Y, and y tend to improve.
The second film and the third film may be a single layer film or may have a laminated structure of two or more layers. For example, it is also preferable that the layered structure is composed of two layers of a core layer and a surface layer, and is formed by co-casting.
In the case of co-casting, for example, a feed block method in which the number of layers can be easily adjusted or a multi-manifold method having excellent thickness accuracy of each layer can be used. In the present invention, the feed block method is more preferable. Can be used.

-Residual solvent amount-
The residual solvent amount of the web (film) was calculated based on the following formula.
Residual solvent amount (% by mass) = {(MN) / N} × 100
[Wherein, M represents the mass of the web (film), and N represents the mass when the web (film) is dried at 110 ° C. for 3 hours. ]

-Steam contact process-
In the manufacturing method of the second film and the third film, a step of maintaining a state in which a contact gas, which will be described later, is contacted as a substitute for the post-heat treatment step or in addition to the post-heat treatment step (steam contact step) as necessary. Can also be applied. Although the effect of a water vapor contact process is not limited, the dimensional change rate of a film and the retardation change at the time of hold | maintaining a film in a humid heat environment can be suppressed by a short time process. Without being bound by any theory, this means that when the second and third films are brought into contact with the contact gas described below, the glass transition temperature of the film is lowered, and the structure of the polymer is stabilized in a short time. This effect is believed to be due to the ability to promote conversion, and this effect appears more effectively with polymers with high contact gas absorption. For example, when contacting with water vapor, it is particularly effective to include a hygroscopic polymer such as cellulose acylate or acrylic. In addition, although a vapor contact process can be implemented in arbitrary places, it is preferable to implement after completion | finish of the above-mentioned extending | stretching process or a post-heat treatment process, and the below-mentioned organic solvent contact process. Moreover, you may use together the below-mentioned surface treatment suitably before and after a vapor | steam contact process. Below, the process (steam contact process) of maintaining the state which makes the gas containing water vapor | steam contact a cellulose acylate film is demonstrated.

--Contact gas--
The gas (contact gas) in contact with the second film and the third film in the vapor contact step is not particularly limited as long as it is a gas in which a liquid solvent is in a gas state, but is a gas containing water vapor. It is preferable that the gas is a gas containing water vapor as a main component, more preferably water vapor. Here, the gas included as the main component indicates that gas when it is composed of a single gas, and when it is composed of a plurality of gases, the gas having the highest mass fraction among the constituent gases. It shows that.
The contact gas is preferably a gas generated by a wet gas supply device. Specifically, the solvent in a liquid state is heated by a boiler to be in a gaseous state, and then sent by a blower. The contact gas may be mixed with air as appropriate, and heated after being sent by a blower. Further heating may be performed via the apparatus. Here, the air is preferably heated. The temperature of the contact gas thus produced is preferably 70 to 200 ° C, more preferably 80 to 160 ° C, and most preferably 100 to 140 ° C. When the temperature is higher than the upper limit temperature, the curling of the film becomes strong, which is not preferable. When the temperature is lower than the lower limit temperature, a sufficient effect may not be obtained. When the contact gas contains water, the relative humidity is preferably 20 to 100%, more preferably 40 to 100%, and particularly preferably 60 to 100%.
The solvent in a liquid state indicates a solvent containing water, an organic solvent, or an inorganic solvent. When water is used, soft water, hard water, pure water, or the like can be used, and soft water is preferably used from the viewpoint of boiler protection. Since contamination of the optical film with foreign matter causes deterioration of optical properties and mechanical properties of the optical film as a product, it is preferable to use water with as little foreign matter as possible. Therefore, in order to prevent foreign matter from being mixed into the optical film, it is preferable to use soft water or pure water, and it is more preferable to use pure water. Here, the pure water has an electrical resistivity of at least 1 MΩ or more, particularly the concentration of metal ions such as sodium, potassium, magnesium and calcium is less than 1 ppm, and the anion such as chlorine and nitric acid is less than 0.1 ppm. Refers to concentration. Pure water can be easily obtained by a simple substance such as a reverse osmosis membrane, an ion exchange resin, distillation, or a combination thereof. In the case of using an organic solvent, methanol, acetone, methyl ethyl ketone and the like can be mentioned. Note that the solvent in the liquid state may include a condensate obtained by condensing the recovered gas from which the contact gas has been recovered.

--Contact process--
As a contact method between the second film and the third film and the aforementioned contact gas in the water vapor contact step, a method of applying the contact gas to the optical film, and the second film and the third film are disposed in a space filled with the contact gas. A method or a method of passing through a space filled with a contact gas can be used, and a method of applying the contact gas to the second film and the third film, or a method of passing through a space filled with the contact gas is preferable. Further, the contact between the optical film and the contact gas is preferably performed while the second film and the third film are conveyed by a plurality of rollers arranged in a staggered manner.
The contact time with the contact gas is not particularly limited, but is preferably as short as possible from the viewpoint of production efficiency as long as the effect is within a range. For example, the upper limit value of the processing time is preferably 3600 seconds or less, and more preferably 600 seconds or less. On the other hand, the lower limit of the processing time is, for example, preferably 10 seconds or more, and more preferably 30 seconds or more.
Although the temperature of the 2nd film and 3rd film when contacting with contact gas is not specifically limited, It is preferable that it is 50-150 degreeC.
Further, the amount of residual solvent in the second film and the third film before contact with water vapor is not particularly limited, but it is preferable that the fluidity of the cellulose acylate molecule is almost lost, and it is preferably 0 to 5% by mass. 0 to 0.3% by mass is more preferable.
The contact gas in contact with the second film and the third film may be sent to a condensing device to which a cooling device is connected, and may be divided into a heated gas and a condensate.

-Step of contacting with an organic solvent-
In the manufacturing method of the second film and the third film, for example, the adhesion of the surfaces of the second film and the third film is improved by contacting and drying the organic solvent on the surfaces of the second film and the third film. It can also be made. Therefore, when the organic solvent is brought into contact with only one side of the second film and the third film, when the second film and the third film are directly bonded to the polarizer, the side brought into contact with the organic solvent is the polarizer. It is preferable to set it as the bonding surface. As a contact method between the second film and the third film and the organic solvent in the organic solvent contact step, generally known contact methods such as dip coating, air knife coating, curtain coating, roller coating, and wire are used. A bar coating method, a gravure coating method, a slide coating method, a spray method, a die coating method, an extrusion coating method using a hopper described in US Pat. No. 2,681,294, or a micro gravure coating method can be used. Moreover, an organic solvent can also be made to contact an organic solvent instead of the water which is a main solvent in a water vapor | steam contact process by using an organic solvent.

-Surface processing-
When the second film and the third film are used for a polarizing plate protective film of an image display device which is the main application, in the solution casting film forming method, in addition to the solution casting film forming device, an undercoat layer, an antistatic layer A coating device may be added for surface processing of an optical film such as a layer, an antihalation layer, or a protective layer. These are described in detail on pages 25 to 30 in the Japan Society for Invention and Innovation Technical Report (Public Technical Number 2001-1745, published on March 15, 2001, Japan Society of Inventions). Including), metal support, drying, peeling, etc., and can be preferably used.

-Surface treatment-
The 2nd film and the 3rd film can achieve improvement of adhesion with the 2nd film and the 3rd film, and each functional layer (for example, undercoat layer and back layer) by carrying out surface treatment depending on the case. . For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs under a low pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferred. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail in pages 30 to 32 in the Japan Institute of Invention Disclosure Technical Bulletin (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention), and are preferably used in the present invention. be able to.

(Use and function of second film and third film)
-Functional layer-
The second film and the third film are applied to an image display device. In particular, the image display device is preferably a liquid crystal display device, and the liquid crystal display device has a liquid crystal cell in which a liquid crystal is supported between two electrode substrates, two polarizers disposed on both sides thereof, and a liquid crystal It is more preferable that at least one optical compensation sheet is arranged between the cell and the polarizer. As these liquid crystal display devices, TN, IPS, FLC, AFLC, OCB, STN, ECB, VA and HAN are preferable.
In that case, when using the above-mentioned 2nd film and 3rd film for an image display apparatus, providing various functional layers may be implemented. These are, for example, an antistatic layer, a cured resin layer (transparent hard coat layer), an antireflection layer, an easy adhesion layer, an antiglare layer, an optical compensation layer, an alignment layer, a liquid crystal layer, and the like. The polarizing plate of the present invention has an antistatic layer, a cured resin layer, an antireflection layer, an antiglare layer, an optical compensation layer, an alignment layer, a surface opposite to the surface on which the first film of the second film is laminated. It is preferable to include a functional layer selected from liquid crystal layers. Examples of these functional layers and materials thereof include surfactants, slip agents, matting agents, antistatic layers, hard coat layers, etc., and are disclosed by the Japan Institute of Technology (Technical Number 2001-1745, March 15, 2001). (Nippon Issuance, Invention Association), page 32 to page 45, and can be preferably used in the present invention.

-Retardation film-
The second film and the third film can be used as a retardation film. The “retardation film” is generally used for a display device such as a liquid crystal display device, and means an optical material having optical anisotropy, and is synonymous with a retardation plate, an optical compensation film, an optical compensation sheet, and the like. It is. In a liquid crystal display device, a retardation film is used for the purpose of improving the contrast of a display screen or improving viewing angle characteristics and color.
By using the second film and the third film, retardation can be freely controlled, and a retardation film excellent in adhesiveness with a polarizer can be produced.

  In addition, a plurality of second films and third films can be laminated, or a second film, a third film, and other films can be laminated, and Re and Rth can be appropriately adjusted to be used as a retardation film. . Lamination of the film can be performed using an adhesive or an adhesive.

In some cases, the second film and the third film may be used as a support for the retardation film, and an optically anisotropic layer made of liquid crystal or the like may be provided thereon to be used as the retardation film. The optically anisotropic layer applied to the retardation film may be formed from, for example, a composition containing a liquid crystal compound, may be formed from a polymer film having birefringence, the second film, and You may form from a 3rd film.
As the liquid crystal compound, a discotic liquid crystal compound or a rod-like liquid crystal compound is preferable.

--Discotic liquid crystalline compound--
Examples of discotic liquid crystalline compounds that can be used as liquid crystalline compounds include various documents (for example, C. Destrade et al., Mol. Crysr. Liq. Cryst., Vol. 71, page 111 (1981); Japan). Chemistry Association, Quarterly Review, No. 22, Liquid Crystal Chemistry, Chapter 5, Chapter 10 Section 2 (1994); B. Kohne et al., Angew. Chem. Soc. Chem. Comm., Page 1794. (1985); J. Zhang et al., J. Am. Chem. Soc., Vol. 116, page 2655 (1994)).

  In the optically anisotropic layer, the discotic liquid crystalline molecules are preferably fixed in an aligned state, and most preferably fixed by a polymerization reaction. Further, the polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284. In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. Discotic liquid crystalline molecules having a polymerizable group are disclosed in JP-A No. 2001-4387.

-Rod-like liquid crystalline compound-
In the optically anisotropic layer, the rod-like liquid crystalline molecules are preferably fixed in an aligned state, and most preferably fixed by a polymerization reaction. Examples of polymerizable rod-like liquid crystalline compounds that can be used in the present invention are described in, for example, Makromol. Chem. 190, 2255 (1989), Advanced Materials 5, 107 (1993), U.S. Pat. Nos. 4,683,327, 5,622,648, 5,770, No. 107 specification, International Publication No. 95/22586 pamphlet, No. 95/24455 pamphlet, No. 97/00600 pamphlet, No. 98/23580 pamphlet, No. 98/52905 pamphlet, JP-A-1-272551, The compounds described in JP-A-6-16616, JP-A-7-110469, JP-A-11-80081, JP-A-2001-328773, and the like are included.

-Hard coat film, antiglare film, antireflection film-
The second film and the third film can be a hard coat film, an antiglare film, or an antireflection film. For the purpose of improving the visibility of flat panel displays such as LCD, PDP, CRT, EL, etc., either or all of a hard coat layer, an antiglare layer and an antireflection layer are provided on one or both sides of the second film and the third film. Can be granted. Preferred embodiments of such an antiglare film and antireflection film are described in detail in pages 54 to 57 of the Japan Institute of Invention and Technology (Publication No. 2001-1745, published on March 15, 2001, Japan Society of Invention). Have been described.

[Image display device]
The image display device of the present invention is an image display device including the polarizing plate of the present invention.
The image display device is preferably a liquid crystal display device.

<Liquid crystal display device>
In general, a liquid crystal display device includes a liquid crystal cell between two polarizing plates. The polarizing plate of the present invention may be used for any of the two polarizing plates, but is preferably used for the polarizing plate on the viewing side (front side).

  The polarizing plate of the present invention can be used for liquid crystal display devices in various display modes. Each liquid crystal mode will be described below. Among these modes, the polarizing plate of the present invention can be preferably used in all modes, but is particularly preferably used for VA mode and IPS mode liquid crystal display devices. These liquid crystal display devices may be any of a transmissive type, a reflective type, and a transflective type.

(TN type liquid crystal display device)
The polarizing plate of the present invention can be used in an image display device using a second film and a third film as a support for a retardation film of a TN type liquid crystal display device having a TN mode liquid crystal cell. Regarding the retardation film used in the TN type liquid crystal display device, each of JP-A-3-9325, JP-A-6-148429, JP-A-8-50206, and JP-A-9-26572, and Mori. Other papers (Jpn. J. Appl. Phys. Vol. 36 (1997) p. 143 and Jpn. J. Appl. Phys. Vol. 36 (1997) p. 1068) are described.

(STN type liquid crystal display device)
The polarizing plate of the present invention may be used in an image display device using a second film and a third film as a support for a retardation film of an STN type liquid crystal display device having an STN mode liquid crystal cell. In general, in a STN type liquid crystal display device, rod-like liquid crystalline molecules in a liquid crystal cell are twisted in the range of 90 to 360 degrees, and the refractive index anisotropy (Δn) and cell gap (d) of the rod-like liquid crystalline molecules. Product (Δnd) is in the range of 300 to 1500 nm. The retardation film used in the STN type liquid crystal display device is described in JP-A No. 2000-105316.

(VA type liquid crystal display device)
The polarizing plate of the present invention may be used for a retardation film of a VA liquid crystal display device having a VA mode liquid crystal cell or an image display device using a second film and a third film as a support for the retardation film. The VA-type liquid crystal display device may be an alignment-divided system as described in, for example, JP-A-10-123576. In these embodiments, the polarizing plate using the second film and the third film contributes to widening the viewing angle and improving the contrast.

(IPS liquid crystal display device and ECB liquid crystal display device)
The polarizing plate of the present invention is a IPS liquid crystal display device having a liquid crystal cell of IPS mode and ECB mode, a retardation film of the ECB liquid crystal display device, a support for the retardation film, or a second film as a protective film for the polarizing plate. It is particularly preferable to use it for an image display device using a third film. In these modes, the liquid crystal material is aligned substantially in parallel during black display, and black is displayed by aligning liquid crystal molecules in parallel with the substrate surface in the absence of applied voltage.
In this embodiment, out of the protective films for the upper and lower polarizing plates of the liquid crystal cell, the polarizing plate using the second film as the protective film (the protective film on the cell side) disposed between the liquid crystal cell and the polarizing plate is liquid crystal. It is preferable to use it above and below the cell. More preferably, an optically anisotropic layer in which the retardation value of the optically anisotropic layer between the protective film of the polarizing plate and the liquid crystal cell is set to not more than twice the value of Δn · d of the liquid crystal layer is provided on one side. It is preferable to arrange in the above.

(OCB type liquid crystal display device and HAN type liquid crystal display device)
The polarizing plate of the present invention uses the second film and the third film as a support for the retardation film of an OCB type liquid crystal display device having an OCB mode liquid crystal cell or a HAN type liquid crystal display device having a HAN mode liquid crystal cell. You may use for an image display apparatus. A retardation film used for a CB type liquid crystal display device or a HAN type liquid crystal display device is described in JP-A-9-197397. Moreover, it is described in Mori et al. (Jpn. J. Appl. Phys. Vol. 38 (1999) p. 2837).

(Reflective liquid crystal display)
The polarizing plate of the present invention is used for an image display device using a second film and a third film as a retardation film of a TN type, STN type, HAN type, GH (Guest-Host) type reflective liquid crystal display device. Also good. The TN-type reflective liquid crystal display device is described in JP-A-10-123478, WO98 / 48320 pamphlet, and Japanese Patent No. 3022477. The retardation film used in the reflective liquid crystal display device is described in International Publication No. 00/65384 pamphlet.

(Other liquid crystal display devices)
The polarizing plate of the present invention may be used for an image display device using a second film and a third film as a support for a retardation film of an ASM type liquid crystal display device having a liquid crystal cell of ASM (Axial Symmetrical Microcell) mode. Good. The ASM-mode liquid crystal cell is maintained by a resin spacer whose cell thickness can be adjusted. Other properties are the same as those of the TN mode liquid crystal cell. The ASM mode liquid crystal cell and the ASM type liquid crystal display device are described in a paper by Kume et al. (Kume et al., SID 98 Digest 1089 (1998)).
Further, the polarizing plate of the present invention is a retardation film preferably used in a video display panel capable of displaying 3D stereoscopic video display, and an image display using the second film and the third film as a support for the retardation film. It can also be used in an apparatus. Specifically, a λ / 4 layer can be formed on the entire surface of the second film or the third film, or a patterned retardation layer having different birefringence can be formed alternately in a line shape, for example. . As the second film and the third film, when a film having a small dimensional change rate with respect to a change in humidity is used as compared with a conventional cellulose acylate film, it can be preferably used particularly in the latter.

  The features of the present invention will be described more specifically with reference to examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

[Production example]
<Production and evaluation of second film and third film>
The second film and the third film were produced by selecting those listed in Table 5 or Table 6 from the materials and production methods shown below.

(Preparation of cellulose acylate solution)
1] Cellulose acylate The following cellulose acylate A was used. Each cellulose acylate was heated to 120 ° C. and dried to adjust the water content to 0.5% by mass or less, and then 20 parts by mass was used.

Cellulose acylate A:
A cellulose acetate powder having a substitution degree of 2.86 was used. Cellulose acylate A has a viscosity average degree of polymerization of 300, an acetyl group substitution degree at the 6-position of 0.89, an acetone extract of 7% by mass, a mass average molecular weight / number average molecular weight ratio of 2.3, and a water content of 0.3. Viscosity in 2 mass% and 6 mass% dichloromethane solutions is 305 mPa · s, residual acetic acid content is 0.1 mass% or less, Ca content is 65 ppm, Mg content is 26 ppm, iron content is 0.8 ppm, sulfate ion The content was 18 ppm, the yellow index was 1.9, and the amount of free acetic acid was 47 ppm. The average particle size of the powder was 1.5 mm, and the standard deviation was 0.5 mm.

・Ｃ−２：エタンジオール／フタル酸（１／１モル比）の縮合物の両末端の酢酸エステル体、数平均分子量８００、水酸基価０ｍｇＫＯＨ／ｇ
・Ｃ−３：エタンジオール／アジピン酸（１／１モル比）の縮合物、数平均分子量１０００、水酸基価１１２ｍｇＫＯＨ／ｇ
・Ｄ−１：下記構造の化合物

2] Additives The additives listed in Table 5 or 6 below were selected from the following additive group. In Table 5 or 6 below, “addition amount” represents mass% (phr) when the mass of the polymer constituting the film is 100 mass%. The amount of addition to the cellulose acylate solution was adjusted so as to be an amount.
-Plasticizer-
A-1: Mixture of triphenyl phosphate / biphenyl diphenyl phosphate (2/1 mass ratio) B-1: Compound having the following structure

C-2: Acetic ester at both ends of the condensate of ethanediol / phthalic acid (1/1 molar ratio), number average molecular weight 800, hydroxyl value 0 mgKOH / g
C-3: Condensate of ethanediol / adipic acid (1/1 molar ratio), number average molecular weight 1000, hydroxyl value 112 mgKOH / g
D-1: Compound having the following structure

-UV absorber-
L-1: Compound having the following structure

L-2: Compound having the following structure

L-3: Compound having the following structure

-Other additives-
R-1: Compound having the following structure (compound for improving polarizer durability)

-Inorganic fine particles-
・ M-1:
Silicon dioxide fine particles (particle size 16 nm, Mohs hardness about 7) (0.02 parts by mass)

・ M-2:
Silicon dioxide fine particles (particle size 20 nm, Mohs hardness about 7) (0.05 parts by mass)

3] Solvent The solvent described in Table 5 or 6 was selected from the following solvents, and 80 parts by mass were used. The water content of each solvent was 0.2% by mass or less.
Solvent A dichloromethane / methanol / butanol = 81/18/1 (mass ratio)
Solvent B dichloromethane / methanol = 87/13 (mass ratio)

4] Dissolution Cellulose acylate was gradually added to a 4000 liter stainless steel dissolution tank having a stirring blade while stirring and dispersing the solvent and additives. After completion of the addition, the mixture was stirred at room temperature for 2 hours, swollen for 3 hours, and then stirred again to obtain a cellulose acylate solution.
For stirring, a dissolver type eccentric stirring shaft that stirs at a peripheral speed of 5 m / sec (shear stress 5 × 10 ⁴ kgf / m / sec ² [4.9 × 10 ⁵ N / m / sec ² ]). In addition, an agitation shaft having an anchor blade on the central axis and stirring at a peripheral speed of 1 m / sec (shear stress 1 × 10 ⁴ kgf / m / sec ² [9.8 × 10 ⁴ N / m / sec ² ]) is used. It was. Swelling was carried out with the high speed stirring shaft stopped and the peripheral speed of the stirring shaft having anchor blades set at 0.5 m / sec.
The swollen solution was heated from a tank to 50 ° C. with a jacketed pipe, and further heated to 90 ° C. with 1.2 MPa pressurization to be completely dissolved. The heating time was 15 minutes. At this time, a filter, a housing, and a pipe that are exposed to a high temperature were made of Hastelloy alloy (registered trademark) and had excellent corrosion resistance, and a thing having a jacket for circulating a heat medium for heat retention and heating was used.
Next, the temperature was lowered to 36 ° C. to obtain a cellulose acylate solution.

  The pre-concentration dope thus obtained was flushed at 80 ° C. in a normal pressure tank, and the evaporated solvent was recovered and separated by a condenser. The solid concentration of the dope after flashing was 24.8% by mass. The condensed solvent was sent to a recovery process to be reused as a solvent in the preparation process (recovery is carried out by a distillation process, a dehydration process, etc.). In the flash tank, defoaming was carried out by stirring by rotating a shaft having an anchor blade on the central shaft at a peripheral speed of 0.5 m / sec. The temperature of the dope in the tank was 25 ° C., and the average residence time in the tank was 50 minutes.

5] Filtration Next, it was first passed through a sintered fiber metal filter having a nominal pore diameter of 10 μm, and then passed through a sintered fiber filter of 10 μm. The dope temperature after filtration was adjusted to 36 ° C. and stored in a 2000 L stainless steel stock tank.

(Production of second film and third film)
The process described in Table 5 or 6 was selected from the following film forming processes.
-Process A-
1) Casting process Subsequently, the dope in the stock tank was fed. The casting die had a width of 3.1 m, a casting width of 3000 mm, and was equipped with a feed block adjusted for co-casting so that a three-layer film could be formed. And the above-mentioned dope is branched and used for the surface layer of the mainstream (intermediate layer), the support surface side and the opposite side (air surface side), respectively, and the matting agent described in Table 5 or Table 6 is applied only to the surface layer dope. By adding, the flow rate of the dope at the die protrusion was adjusted to perform casting. The flow rate of the dope for the surface layer was adjusted so that the film thickness of the surface layer was 3 μm on both the support surface side and the air surface side. In order to adjust the dope temperature to 36 ° C., a jacket was provided on the casting die, and the inlet temperature of the heat transfer medium supplied into the jacket was set to 36 ° C.
The die, feed block, and piping were all kept at 36 ° C. during the work process.

2) Casting die The material of the die is a two-phase stainless steel with a mixed composition of austenite phase and ferrite phase, and has a coefficient of thermal expansion of 2 × 10 ^-6 (° C ^-1 ) or less. A material having corrosion resistance substantially equivalent to that of SUS316 was used in a forced corrosion test in an aqueous solution.
In addition, the lip tip of the casting die used was a WC coating formed by a thermal spraying method. A mixed solvent (dichloromethane / methanol / butanol (83/15/2 parts by mass)), which is a solvent for solubilizing the dope, was supplied to the gas-liquid interface between the bead end and the slit at 0.5 ml / min on one side.

3) Metal support The dope extruded from the die used a mirror-surface stainless steel support that is a drum having a width of 3.5 m and a diameter of 3 m as a support. The surface was nickel cast and hard chrome plated. The surface roughness of the drum is polished to 0.01 μm or less, there are no pinholes of 50 μm or more, pinholes of 10 to 50 μm are 1 / m ² or less, and pinholes of 10 μm or less are 2 / m ² or less A support was used. At this time, the temperature of the drum was set to −5 ° C., and the number of revolutions of the drum was set so that the peripheral speed of the drum was 100 m / min.

4) Casting drying Subsequently, the dope which has been cast on a drum placed in a space set at 15 ° C., cooled and gelled is rotated by 320 ° on the drum, and then the gelated film (web) ). At this time, the stripping speed was adjusted with respect to the support speed, and the film was stretched in the transport direction. The drawing direction is shown in MD and Tables 5 and 6 below together with the draw ratio in the conveying direction. However, the film whose stretching direction is described as TD in Table 5 had a stretching ratio in the transport direction within 1%. The amount of residual solvent at the time of stretching was between 170 and 280% by mass.

5) Tenter Transport / Drying Process Conditions The peeled web was transported through the drying zone and dried with a drying wind after both ends were fixed with a tenter having a pin clip or stretched in the width direction. In Table 5 below, the film whose stretching direction is described as TD represents that it was stretched in the width direction, and the stretching ratio is also listed in Table 5 below. In the following Table 5, the film in which the stretching direction is described as MD was conveyed in the drying zone while the web was fixed at both ends with a tenter having a pin clip, and the stretching ratio in the width direction was 0 to 1%. .

-Process B-
1) Casting process Subsequently, the dope in the stock tank was fed. The casting die had a width of 3.1 m, a casting width of 3000 mm, and was equipped with a feed block adjusted for co-casting so that a three-layer film could be formed. And the above-mentioned dope is branched and used for the surface layer of the mainstream (intermediate layer), the support surface side and the opposite side (air surface side), respectively, the matting agent described in Table 5 is added only to the surface layer dope, Casting was performed by adjusting the flow rate of the dope at the die protrusion. The flow rate of the dope for the surface layer was adjusted so that the film thickness of the surface layer was 2 μm on both the support surface side and the air surface side. In order to adjust the dope temperature to 30 ° C., a jacket was provided on the casting die, and the inlet temperature of the heat transfer medium supplied into the jacket was set to 30 ° C.
The die, feed block, and piping were all kept at 30 ° C. during the work process.

2) Casting die The material of the die is a two-phase stainless steel with a mixed composition of austenite phase and ferrite phase, and has a coefficient of thermal expansion of 2 × 10 ^-6 (° C ^-1 ) or less. A material having corrosion resistance substantially equivalent to that of SUS316 was used in a forced corrosion test in an aqueous solution.
In addition, the lip tip of the casting die used was a WC coating formed by a thermal spraying method. A mixed solvent (dichloromethane / methanol (85/15 parts by mass)), which is a solvent for solubilizing the dope, was supplied to the gas-liquid interface between the bead end and the slit at 0.5 ml / min on one side.

3) Metal support The dope extruded from the die used a mirror surface stainless steel support having a band length of 60 m as a support. At this time, the temperature of the band was set to 15 ° C., and the peripheral speed of the band was set to 50 m / min.

4) Casting drying Subsequently, the dope casted on a band arranged in a space set at 15 ° C. and drying progressed to exhibit self-supporting ability is 50 cm before the end point of the casting part. It was peeled off as a film (web) containing a solvent.
The peeled web was stretched in the transport direction by adjusting the web take-up speed. The drawing directions are shown in MD, Table 5, and Table 6 together with the draw ratio in the conveying direction. The amount of residual solvent at the time of stretching was between 40 and 150% by mass.

5) Tenter Transport / Drying Process Conditions The stretched web was transported through the drying zone while being fixed at both ends with a tenter having a clip, and dried with drying air. Since the web was conveyed in the drying zone with both ends fixed by a tenter having a clip, the draw ratio in the width direction was 0 to 1%.

  The film produced in the film forming step was subjected to the following drying, post-treatment, and winding steps to obtain the second film or the third film described in Table 5 or 6.

6) Post-drying process conditions The film after the trimming obtained by the method described above was further dried in the roller transport zone. The material of the roller was made of aluminum or carbon steel, and hard chrome plating was applied to the surface. As the surface shape of the roller, a flat one and a mat formed by blasting were used. The produced film was post-heat treated at a temperature of 100 to 140 ° C. for 20 minutes.

7) Post-treatment and winding conditions The dried film was cooled to 30 ° C. or lower and cut off at both ends. For the edge-cutting, two devices for slitting the film edge were installed at the left and right ends of the film (two slit devices per side), and the film edge was slit. Further, knurling was performed on both ends of the film. Knurling was applied by embossing from one side. Thus, a film having a final product width of 2000 mm was obtained and wound up by a winder to produce a second film or a third film.

  In addition, the films 14-18 of Table 5 are TD80UL (film 14), T80UZ (film 15), TD60UL (film 16), TD40UC (film 17), which are commercially available tack films made by FUJIFILM Corporation. TD40UT (film 18) was purchased and used as it was.

(Evaluation of film)
Re and Rth of the second film and the third film used for the polarizing plates of each Example and Comparative Example were measured by the methods described in this specification.
The film thickness, elastic modulus, humidity dimensional change rate, and sound wave velocity of the first film, the second film, and the third film, which will be described later, used for the polarizing plates of each Example and Comparative Example were measured by the following methods.
The obtained results are shown in Tables 5 to 7 below.

-Film thickness-
The thickness of the 1st film, the 2nd film, and the 3rd film was measured using Mitutoyo Corporation high precision digital length measuring machine (VL-50-B).

-Elastic modulus-
A sample of 200 mm (measurement direction) × 10 mm was cut out from the produced first film, second film and third film with the direction parallel to or perpendicular to the absorption axis direction of the first film as the longitudinal direction, and Toyo Baldwin Universal tensile testing machine "ST"
After adjusting the humidity for 24 hours at 25 ° C. and 60% relative humidity using MT50BP ″, the stress at 0.1% elongation and 0.5% elongation was measured at a tensile rate of 10% / min. The rate was determined.
As for the elastic modulus, the elastic modulus in the direction parallel to the absorption axis direction of the first film and the elastic modulus in the direction orthogonal to the absorption axis direction of the first film were measured.
For the second film, the value of E _{2 //} / E ₂さ ら に was further calculated.

-Humidity dimensional change rate-
A film sample having a length of 12 cm (measurement direction) and a width of 3 cm is cut with a direction parallel to or perpendicular to the absorption axis direction of the first film as a longitudinal direction, and pin holes are formed in the sample at intervals of 10 cm. after holding for 48 hours at 90% relative humidity environment (the measured value L ₈₀₎ to 24 hours moisture adjustment at 25 ° C. and 80% relative humidity, the distance between the pin holes to the length measured at pin gauge. Next, the sample is conditioned at 25 ° C. and 60% relative humidity for 24 hours, and the distance between the pin holes is measured with a pin gauge (measured value is L ₆₀ ). Subsequently, the sample was conditioned at 25 ° C. and 10% relative humidity for 48 hours, and the distance between the pin holes was measured with a pin gauge (measured value is L ₁₀ ).
The humidity dimensional change rate is calculated by the following formula using these measured values.
Humidity dimensional change rate [%] between 10% and 80% relative humidity = | L ₁₀ −L ₈₀ | / L ₆₀
The humidity dimensional change rate of the first film, the second film, and the third film in the direction parallel to the absorption axis direction of the first film, the humidity dimensional change rate in the direction parallel to the absorption axis direction of the first film, The dimensional change between the relative humidity of 10% and 80% was defined as the humidity dimensional change rate expressed as a percentage with respect to the dimension at the relative humidity of 60%.

-Sound propagation velocity-
In the present invention, the direction in which the sound wave propagation speed becomes maximum is the orientation measuring machine (SST-2500: Nomura) after conditioning the first film, the second film, and the third film at 25 ° C. and a relative humidity of 60% for 24 hours. Was used as the direction in which the propagation speed of the longitudinal vibration of the ultrasonic pulse was maximized.
The direction in which the sound wave propagation speed of the first film, the second film, and the third film was maximum coincided with the direction parallel to the absorption axis direction of the first film.

[Examples 1 to 18 and Comparative Examples 1 to 10]
<Production and Evaluation of Polarizing Plates 1-28>
(Preparation of polarizing plate)
-[1] Saponification of optical film-
After immersing each second film or third film listed in Table 5 or Table 6 below in a 4.5 mol / L potassium hydroxide aqueous solution (saponification solution) adjusted to 55 ° C. for 30 seconds, the film was washed with water, Then, after being immersed in a 0.05 mol / L sulfuric acid aqueous solution for 30 seconds, it was further passed through a washing bath. Then, draining with an air knife was repeated three times, and after dropping water, the film was retained in a drying zone at 70 ° C. for 15 seconds and dried to produce a saponified second film or third film.

-[2] Production of polarizer-
According to the production method of Example 1 of Japanese Patent Application Laid-Open No. 2001-141926, a peripheral speed difference was given between two pairs of nip rolls, and the film was stretched in the longitudinal direction to produce a polarizer. The thickness of the used long polyvinyl alcohol film original fabric was changed, and films 91 to 93 used as the first film described in Table 7 below were obtained.

-[3] Bonding On one side of the polarizer which is the first film described in Table 7 obtained as described above, the second film described in Table 5 subjected to saponification treatment was applied on the other side. After disposing the third film described in Table 6 below, a PVA (manufactured by Kuraray Co., Ltd., PVA-117H) 3% aqueous solution is used as an adhesive, and is bonded by roll-to-roll, and polarizing plates of each Example and Comparative Example 1-28 were produced.

(Evaluation of polarizing plate)
-[1] Initial polarization degree-
When the polarizing plate of each Example and the comparative example was cut out by 40 mm square and the polarization degree was computed by the method mentioned above, the polarization degree of all the polarizing plates was 99.9%.

-[2] Degree of polarization over time 1
When the polarizing plate of each Example and Comparative Example is cut out by 40 mm square, and there is a third film for each polarizing plate, an adhesive layer is formed on the surface, and when there is no third film, the first film A pressure-sensitive adhesive layer was formed on the surface opposite to the two films. The pressure-sensitive adhesive layer was formed by the method disclosed in Example 1 of Japanese Patent Application Laid-Open No. 2003-50313. Each of the polarizing plates was bonded to a glass plate with an adhesive material and allowed to stand for 500 hours under conditions of 60 ° C. and 90% relative humidity, and the degree of polarization after standing (time-dependent polarization degree 1) was calculated by the method described above. The degree of polarization was 99.9%.

-[3] Degree of polarization over time 2-
Similar to the evaluation of degree of polarization over time 1, the polarizing plate was cut out at a 40 mm square, bonded to a glass plate, left in an environment of 80 ° C. and 10% relative humidity for 500 hours, and the degree of polarization after standing (time-dependent polarization degree 2) Was calculated by the method described above, and the degree of polarization of all the polarizing plates was 99.9%.

-[4] Heat cycle cracking-
The polarizing plate was cut out with a size of 700 mm × 400 mm, and the polarizing plate described in Table 8 was bonded to a glass plate via an adhesive material layer. When there was a 3rd film about each polarizing plate, the adhesive material layer was formed in the surface, and when there was no 3rd film, the adhesive material layer was formed in the surface opposite to the 2nd film of a 1st film. The pressure-sensitive adhesive layer was formed by the method disclosed in Example 1 of Japanese Patent Application Laid-Open No. 2003-50313. Each laminate of the polarizing plate and the glass plate was tested for 500 cycles under the test conditions of low temperature −40 ° C. and high temperature + 70 ° C., the appearance of the polarizing plate after the test was confirmed, and evaluated according to the following criteria. It is practically necessary that the heat cycle crack is A or B evaluation, and A evaluation is preferable. The obtained results are shown in Table 8 below.
This method assumes that the liquid crystal display device incorporating the polarizing plate of the present invention is used indoors in a cold region, and polarizing plate cracking in an environment where high and low temperature heat cycles are repeated, that is, heating of the polarizing plate. It is for evaluating cycle durability.
(Polarizing plate cracking situation)
A: No crack was observed.
B: A slight crack having a depth of less than 0.2 mm was confirmed.
C: A crack having a depth of 0.2 mm or more was confirmed.

-[5] Evaluation of mounting on liquid crystal display devices-
(Mounting on IPS liquid crystal display / initial performance)
A pair of polarizing plates sandwiching the liquid crystal cell is peeled off from a commercially available liquid crystal television (IPS mode slim type 42-inch liquid crystal television; LG Electronics 42LS5600), and the second film is opposite to the liquid crystal cell. It re-bonded to the liquid crystal cell through the adhesive material layer so that it may be arrange | positioned at the side. When there was a 3rd film about each polarizing plate, the adhesive material layer was formed in the surface, and when there was no 3rd film, the adhesive material layer was formed in the surface opposite to the 2nd film of a polarizer. The pressure-sensitive adhesive layer was formed by the method disclosed in Example 1 of Japanese Patent Application Laid-Open No. 2003-50313. After confirming the display characteristics of the reassembled liquid crystal television and confirming the brightness and color from the front and diagonal, it was confirmed that the display characteristics were good as before the polarizing plate was attached again. In addition, this display characteristic was preferable also when peeling only the polarizing plate by the side of visual recognition among a pair of polarizing plates which pinch | interpose the liquid crystal cell, and evaluating again.

-Mounting on IPS liquid crystal display device 1 (Change in temperature and humidity at high temperature, edge peeling)-
The manufactured liquid crystal display device was held in an environment of 60 ° C. and a relative humidity of 90% for 3 days, and then held in an environment of 70 ° C. and a relative humidity of 10% for 3 days. After repeating this cycle seven times, the periphery of the display screen was visually observed. The end of the polarizing plate was checked for peeling (floating from the panel) and evaluated according to the following criteria. The evaluation results are shown in Table 8. Temperature / humidity change at high temperature End peeling is practically required to be A or B evaluation, and is preferably A evaluation. The obtained results are shown in Table 8 below.
When this method is incorporated in an image display device incorporating the polarizing plate of the present invention, edge peeling occurs in an environment where temperature and humidity changes at high temperatures are repeated, that is, temperature and humidity changes at high temperatures of the image display device are repeated. It is for evaluating the durability under the environment.
(End peeling condition after temperature and humidity change at high temperature)
A: No peeling or lifting was observed.
B: Slight peeling with a depth of less than 0.2 mm was confirmed.
C: Peeling with a depth of 0.2 mm or more was confirmed.
D: Peeling with a depth of 0.2 mm or more was confirmed, and floating was also confirmed.

-Mounting on IPS liquid crystal display device 2 (humidity fluctuation, uneven brightness)-
The prepared liquid crystal display device is held for 14 days in an environment of 45 ° C. and a relative humidity of 80%, then moved to an environment of 25 ° C. and a relative humidity of 60%, and kept on in a black display state, and visually observed after 4 hours. The brightness unevenness in the front direction was evaluated. Humidity fluctuation The luminance unevenness is practically required to be A or B evaluation, and is preferably A evaluation. The evaluation results are shown in Table 8. The obtained results are shown in Table 8 below.
This method is for evaluating the luminance unevenness in an environment where the humidity fluctuation is large, that is, the humidity fluctuation durability of the image display apparatus when incorporated in the image display apparatus incorporating the polarizing plate of the present invention.
(Front brightness unevenness)
When observed from the front of the image display device, luminance unevenness during black display was observed and evaluated according to the following criteria.
A: Unevenness is not visually recognized under an environment with an illuminance of 100 lx. B: Unevenness is hardly visually recognized under an environment with an illuminance of 100 lx. C: Light unevenness is visually recognized under an environment of an illuminance of 100 lx. Unevenness is visually recognized E: Clear unevenness is visually recognized in an environment with illuminance of 300 lx

From the said Tables 5-8, the polarizing plate of this invention can suppress the edge part peeling of the polarizing plate in the environment where a temperature / humidity change is repeated at high temperature when it incorporates in an image display apparatus, and was incorporated in the image display apparatus. In this case, it was found that the present invention is a polarizing plate that can suppress luminance unevenness in an environment with large humidity fluctuations and can suppress cracking of the polarizing plate in an environment in which high-temperature and low-temperature heat cycles are repeated.
On the other hand, when the value X or the value x exceeds the upper limit defined by the present invention from the polarizing plates 1 to 4 and 23 to 25 of Comparative Examples 1 to 4 and 8 to 10, the humidity fluctuations when incorporated in the image display device It was found that brightness unevenness occurs in an environment with a large.
From the polarizing plates 5 and 10 of Comparative Examples 5 and 6, when the value Y or the value y exceeds the upper limit defined in the present invention, polarizing plate cracking occurs in an environment where high and low temperature heat cycles are repeated, It was found that edge peeling occurred in an environment where temperature and humidity changes were repeated at high temperatures when incorporated in an image display device.
From the polarizing plate 12 of Comparative Example 7, when the value X or the value x exceeds the upper limit value specified in the present invention and the value Y or the value y exceeds the upper limit value specified in the present invention, the heat cycle of high temperature and low temperature If the polarizing plate cracks in an environment where the temperature is repeated, it will be peeled off at the high temperature and humidity changes when it is incorporated in an image display device, and the humidity will be reduced if it is incorporated in an image display device. It was found that uneven brightness occurred in an environment with large fluctuations.

Claims (13)

Having the second film, the first film and the adhesive layer in this order,
The first film and the adhesive layer are in direct contact;
The first film is a polarizer;
The absorption axis direction of the first film and the direction in which the elastic modulus of the second film is maximum are parallel,
The value X calculated from the following formula (1) is 135 or less,
A polarizing plate having a value Y calculated from the following formula (2) of 0.30 or less;
Expression (1): X = E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //}
Formula (2): Y = (σ _// + σ⊥) / {(E _{2 //} + E ₂ ⊥) × d ₂ }
Formula (2A-1): σ _// = {E _{1 //} × d ₁ × | ε _{p // −} ε _{1 //} |}
Formula (2A-2): ε _{p //} = (E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} ) / (E _{1 //} × d ₁ + E _{2 / /} × d ₂₎
Formula (2B-1): σ⊥ = {E ₁ ⊥ × d ₁ × | ε _p ⊥−ε ₁ ⊥ |}
Formula (2B-2): ε _p ⊥ = (E ₁ ⊥ × d ₁ × ε ₁ ⊥ + E ₂ ⊥ × d ₂ × ε ₂ ⊥) / (E ₁ ⊥ × d ₁ + E ₂ ⊥ × d ₂ )
Where
E _{1 //} represents the elastic modulus of the first film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₁表 し represents the elastic modulus of the first film in a direction orthogonal to the absorption axis direction of the first film, and the unit is GPa;
d ₁ represents the film thickness of the first film, the unit is μm;
ε _{1 //} is the humidity expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the first film in the direction parallel to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents the rate of dimensional change;
ε ₁ ⊥ is a humidity dimension in which the dimensional change between the relative humidity of 10% and 80% of the first film in the direction perpendicular to the absorption axis direction of the first film is expressed as a percentage of the dimension at the relative humidity of 60%. Represents the rate of change;
E _{2 //} represents the elastic modulus of the second film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₂ ⊥ represents the elastic modulus of the second film in the direction perpendicular to the absorption axis direction of the first film, and the unit is GPa;
d ₂ represents the film thickness of the second film, the unit is μm;
ε _{2 //} is the humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the second film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Represents the rate of dimensional change;
ε ₂湿度 is a humidity dimension in which the dimensional change between the relative humidity of 10% and 80% of the second film in the direction orthogonal to the absorption axis direction of the first film is expressed as a percentage of the dimension at the relative humidity of 60%. Represents the rate of change. Having the second film, the first film and the third film in this order,
The first film is a polarizer;
The absorption axis direction of the first film and the direction in which the elastic modulus of the second film is maximum are parallel,
The absorption axis direction of the first film and the direction in which the elastic modulus of the third film is maximum are parallel,
The value x calculated from the following formula (3) is 135 or less,
A polarizing plate having a value y calculated from the following formula (4) of 0.30 or less;
Equation (3): x = E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} + E _{3 //} × d ₃ × ε _{3 //}
Formula (4): y = (σ _// + σ⊥) / {(E _{2 //} + E ₂ ⊥) × d ₂ + (E _{3 //} + E ₃ ⊥) × d ₃ }
Formula (4A-1): σ _// = {E _{1 //} × d ₁ × | ε _{p // −} ε _{1 //} |}
Formula (4A-2): ε _{p //} = (E _{1 //} × d ₁ × ε _{1 //} + E _{2 //} × d ₂ × ε _{2 //} + E _{3 //} × d ₃ × ε _{3 //} ) _{/ (E 1 // × d 1} + E 2 // × d 2 + E 3 // × d 3)
Formula (4B-1): σ⊥ = {(E ₁ ⊥ × d ₁ × | ε _p ⊥−ε ₁ ⊥ |}
Formula (4B-2): ε _p ⊥ = (E ₁ ⊥ × d ₁ × ε ₁ ⊥ + E ₂ ⊥ × d ₂ × ε ₂ ⊥ + E ₃ ⊥ × d ₃ × ε ₃ ⊥) / (E ₁ ⊥ × d ₁ + E ₂ ⊥ x d ₂ + E ₃ ⊥ x d ₃ )
Where
E _{1 //} represents the elastic modulus of the first film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₁表 し represents the elastic modulus of the first film in a direction orthogonal to the absorption axis direction of the first film, and the unit is GPa;
d ₁ represents the film thickness of the first film, the unit is μm;
ε _{1 //} is the humidity expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the first film in the direction parallel to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents the rate of dimensional change;
ε ₁ ⊥ is a humidity dimension in which the dimensional change between the relative humidity of 10% and 80% of the first film in the direction perpendicular to the absorption axis direction of the first film is expressed as a percentage of the dimension at the relative humidity of 60%. Represents the rate of change;
E _{2 //} represents the elastic modulus of the second film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₂ ⊥ represents the elastic modulus of the second film in the direction perpendicular to the absorption axis direction of the first film, and the unit is GPa;
d ₂ represents the film thickness of the second film, the unit is μm;
ε _{2 //} is the humidity expressed as a percentage of the dimensional change between 10% and 80% relative humidity of the second film in the direction parallel to the absorption axis direction of the first film relative to the dimension at 60% relative humidity. Represents the rate of dimensional change;
ε ₂湿度 is a humidity dimension in which the dimensional change between the relative humidity of 10% and 80% of the second film in the direction orthogonal to the absorption axis direction of the first film is expressed as a percentage of the dimension at the relative humidity of 60%. Represents the rate of change.
E _{3 //} represents the elastic modulus of the third film in a direction parallel to the absorption axis direction of the first film, and the unit is GPa;
E ₃表 し represents the elastic modulus of the third film in the direction perpendicular to the absorption axis direction of the first film, and the unit is GPa;
d ₃ represents the film thickness of the third film, and the unit is μm;
ε _{3 //} is the humidity expressed as a percentage of the dimensional change between the relative humidity of 10% and 80% of the third film in the direction parallel to the absorption axis direction of the first film with respect to the dimension at the relative humidity of 60%. Represents the rate of dimensional change;
ε ₃ ⊥ is a humidity dimension in which the dimensional change between the relative humidity of 10% and 80% of the third film in the direction orthogonal to the absorption axis direction of the first film is expressed as a percentage of the dimension at the relative humidity of 60%. Represents the rate of change. The polarizing plate according to claim 2, wherein the film thickness d ₂ of the second film and the film thickness d ₃ of the third film are both 35.0 μm or less.   The polarizing plate according to claim 2, wherein the first film and the third film are in direct contact.   The polarizing plate according to claim 1, wherein the second film and the first film are in direct contact. The polarizing plate according to claim 1, wherein a value obtained by dividing the elastic modulus E _{2 //} of the second film by the elastic modulus E ₂の of the second film is 1.20 or more. The polarizing plate according to claim 1, wherein a value obtained by dividing the elastic modulus E _{2 //} of the second film by the elastic modulus E ₂の of the second film is 1.40 or more. The polarizing plate according to claim 1, wherein the second film has an elastic modulus E _{2 //} of 5.5 to 10.0 GPa.   The polarizing plate according to any one of claims 1 to 8, wherein the value X calculated from the formula (1) or the value x calculated from the formula (3) is 120 or less.   10. The polarizing plate according to claim 1, wherein the value Y calculated from the formula (2) or the value y calculated from the formula (4) is 0.22 or less.   The surface of the second film opposite to the surface on which the first film is laminated is selected from an antistatic layer, a cured resin layer, an antireflection layer, an antiglare layer, an optical compensation layer, an alignment layer, and a liquid crystal layer. The polarizing plate as described in any one of Claims 1-10 containing a functional layer.   The polarizing plate according to any one of claims 1 to 11, wherein the second film contains at least cellulose acylate as a polymer.   The image display apparatus containing the polarizing plate as described in any one of Claims 1-12.