JP2017068235A - Polarizing plate protective film, manufacturing method of the same, polarizing plate, and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing plate protective film including a cellulose ester layer, the polarizing plate protective film excellent in low moisture permeability and interlayer adhesion and a manufacturing method of the same, and a polarizing plate and a liquid crystal display.SOLUTION: There are provided a polarizing plate protective film comprising a polymer B1 layer containing a polymer B1 that is adjacent to at least one surface of a cellulose ester layer and includes a repeating unit having a solubility parameter δt of 13.5 or more and less than 20.0, where the polymer B1 layer is formed by applying, onto a surface of the cellulose ester layer, a composition containing the polymer B1 and a solvent satisfying specific relational expressions [1] and [2], and has a moisture permeability for six hours in a condition of 85°C and a relative humidity of 85% is 100 g/mor more and 1600 g/mor less, and a manufacturing method of the same; and a polarizing plate and a liquid crystal display.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polarizing plate protective film, a production method thereof, a polarizing plate, and an image display device.

Image display devices represented by electroluminescence displays (ELDs) and liquid crystal display devices (LCDs) are increasingly required to be thin. In addition, the usage environment of image display devices has been diversified, including outdoor applications, and image display devices can stably maintain good image quality even in harsh environments compared to conventional ones (high durability of performance) ) Is now required.
The decrease in image quality in the image display apparatus is partly caused by moisture entering the polarizing plate and degrading the polarizer. The polarizer is protected by laminating a protective film (optical film) on the surface, but the protective film is also required to be thin. When the protective film is thinned, moisture is more likely to come into contact with the polarizer, and the image quality is likely to deteriorate. Such a decrease in image quality becomes more apparent when used in harsh environments such as outdoor applications.

  As the optical film, cellulose resins are widely used from the viewpoint of versatility or processability. From the need to further increase the durability, optical films are being modified (for example, Patent Documents 1 to 6).

JP-A-9-197128 JP 2012-172062 A JP2015-11059A JP 2014-115473 A JP 2014-24254 A JP 2014-48433 A

As a result of repeated investigations from the viewpoint of suppressing the deterioration of the polarizer, the present inventors, as well as the conventional protective films including the films described in the above-mentioned patent documents, are particularly thinned to the above-mentioned required level. It has become clear that the moisture permeability is high and it is difficult to sufficiently suppress the deterioration of the polarizer under high temperature and high humidity conditions.
Furthermore, when a polarizing plate using a protective film having a two-layer structure provided with a moisture-proof layer (for example, Patent Documents 1 and 4) is exposed to high temperature and high humidity conditions for a long time, the moisture-proof layer peels off and durability is improved. I found it was not enough.

  This invention makes it a subject to provide the polarizing plate protective film provided with the cellulose-ester layer, Comprising: The polarizing plate protective film excellent in low moisture permeability and interlayer adhesiveness, and its manufacturing method. The present invention also provides a polarizing plate capable of suppressing deterioration in image quality when used for a long time under high temperature and high humidity conditions when incorporated in an image display device, and an image display device using the polarizing plate. It is an issue to provide.

  As a result of intensive studies in view of the above problems, the inventors of the present invention specified a layer containing a polymer containing a repeating unit having a solubility parameter within a specific range with respect to each of the above polymer and cellulose ester and the fd value described later. In a specific film formation method using a composition containing a solvent that satisfies the relationship and the polymer, a polarizing plate protective film provided adjacent to the cellulose ester layer has improved interlayer adhesion between the polymer layer and the cellulose ester layer. It has been found that it is excellent and exhibits low moisture permeability, and that it can effectively suppress deterioration of the polarizer even under high temperature and high humidity conditions by using it as a protective film for the polarizer. The present invention has been further studied and completed based on these findings.

<1> having a cellulose ester layer containing a cellulose ester and a polymer B1 layer containing a polymer B1 adjacent to at least one surface of the cellulose ester layer;
Polymer B1 contains the following repeating unit [a]:
The polymer B1 layer is formed by applying a composition containing the polymer B1 and a solvent in which fd defined by the following formula I satisfies the following relational expressions [1] and [2] on the surface of the cellulose ester layer. ,
85 ° C., 85% relative humidity conditions, the polarizer protective film moisture permeability is 1600 g / ^{m 2} or less 100 g / ^{m 2} or more at 6 hours.
[A]: Repeating unit in which solubility parameter δt calculated by Hoy method is 13.5 or more and less than 20.0 Relational expression [1] | fd _solvent −fd _cellulose | ≦ 0.050
Relational expression [2] | fd _solvent −fd _polymerB1 | ≦ 0.050
In the relational expressions [1] and [2], fd _solvent represents the fd value of the solvent, fd _cellulose represents the fd value of the cellulose ester, and fd _polymerB1 represents the fd value of the polymer B1.
Here, the fd value is defined by the following formula I. Formula I fd = δd / (δd + δp + δh)
In Formula I, δd, δp, and δh are a term corresponding to the London dispersion force, a term corresponding to the force between dipoles, and a term corresponding to the hydrogen bonding force, respectively, with respect to the solubility parameter δt calculated by the Hoy method. Fd represents the ratio of δd to the sum of δd, δp, and δh.
<2> The polarizing plate protective film according to <1>, wherein the polymer B1 includes the following repeating unit [b].
[B]: repeating unit <3> having a solubility parameter δt calculated by the Hoy method of 20.0 or more and 26.0 or less <3> containing polymer B2 adjacent to the surface opposite to the cellulose ester layer of the polymer B1 layer Having a polymer B2 layer
The polarizing plate protective film according to <2>, wherein the polymer B2 contains the following repeating unit [a] and does not contain the repeating unit [b].
[A]: Repeating unit in which solubility parameter δt calculated by Hoy method is 13.5 or more and less than 20.0 [b]: Solubility parameter δt calculated by Hoy method is 20.0 or more and 26.0 or less The polarizing plate protective film according to any one of <1> to <3>, wherein the repeating unit <4> polymer B1 layer is formed by coating the composition on the surface of the cellulose ester layer.
<5> On at least one surface of a cellulose ester layer containing a cellulose ester, a polymer B1 and a solvent in which fd defined by the following formula I satisfies the following relational expressions [1] and [2] are contained. The manufacturing method of the polarizing plate protective film as described in any one of <1>-<3> including the process of applying the composition to do.
Relational expression [1] | fd _solvent -fd _cellulose | ≦ 0.050
Relational expression [2] | fd _solvent −fd _polymerB1 | ≦ 0.050
In the relational expressions [1] and [2], fd _solvent represents the fd value of the solvent, fd _cellulose represents the fd value of the cellulose ester, and fd _polymerB1 represents the fd value of the polymer B1.
Here, the fd value is defined by the following formula I. Formula I fd = δd / (δd + δp + δh)
In Formula I, δd, δp, and δh are a term corresponding to the London dispersion force, a term corresponding to the force between dipoles, and a term corresponding to the hydrogen bonding force, respectively, with respect to the solubility parameter δt calculated by the Hoy method. Fd represents the ratio of δd to the sum of δd, δp, and δh.
<6> A polarizing plate having a polarizer and the polarizing plate protective film according to <1> or <2> provided on at least one surface of the polarizer.
<7> The polarizing plate according to <6>, wherein the polymer B1 layer of the polarizing plate protective film is disposed on the surface side of the polarizer.
<8> A polarizing plate having a polarizer and the polarizing plate protective film according to <3> provided on at least one surface of the polarizer.
<9> The polarizing plate according to <8>, wherein the polymer B2 layer of the polarizing plate protective film is disposed on the surface side of the polarizer.
<10> When a polarizing plate protective film is provided on one surface of the polarizer, the polarizer has a cycloolefin film containing a cycloolefin polymer on the surface opposite to the polarizing plate protective film <6>. The polarizing plate as described in any one of-<9>.
<11> An image display device comprising the polarizing plate according to any one of <6> to <10>.

  The present invention can provide a polarizing plate protective film having a cellulose ester layer, which is excellent in low moisture permeability and interlayer adhesion, and a method for producing the same. The present invention also provides a polarizing plate capable of suppressing deterioration in image quality when used for a long time under high temperature and high humidity conditions when incorporated in an image display device, and an image display device using the polarizing plate. Can be provided.

FIG. 1 is a cross-sectional view showing a preferred embodiment of the polarizing plate protective film of the present invention. FIG. 2 is a cross-sectional view showing a preferred embodiment of the polarizing plate protective film of the present invention. FIG. 3 is a cross-sectional view showing a preferred embodiment of the polarizing plate protective film of the present invention. FIG. 4 is a cross-sectional view showing a preferred embodiment of the polarizing plate protective film of the present invention. FIG. 5 is a cross-sectional view showing a preferred embodiment of the polarizing plate of the present invention. FIG. 6 is a cross-sectional view showing a preferred embodiment of the polarizing plate of the present invention. FIG. 7 is a schematic diagram showing an outline of an embodiment of a liquid crystal display device including a polarizing plate incorporating the polarizing plate protective film of the present invention. FIG. 8 is a partially enlarged schematic view showing an example of a method for producing a cellulose ester layer (co-casting).

  In the present invention, the numerical range represented by “to” means that the numerical values described before and after that are included as the lower limit value and the upper limit value.

  In the present specification, when there are a plurality of substituents, linking groups, etc. (hereinafter referred to as substituents, etc.) indicated by specific symbols, or when a plurality of substituents etc. are specified simultaneously or alternatively, It means that a substituent etc. may mutually be same or different. The same applies to the definition of the number of substituents and the like. Further, when a plurality of substituents and the like are close (especially adjacent), they may be connected to each other or condensed to form a ring.

In this specification, about the display of a compound, it uses in the meaning containing its salt and its ion other than a compound itself. In addition, it means that a part of the structure is changed as long as the desired effect is achieved. Examples of the salt of the compound include an acid addition salt of the compound formed with the compound and an inorganic acid or an organic acid, or a base addition salt of the compound formed with the compound and an inorganic base or an organic base. Is mentioned. In addition, examples of the ion of the compound include an ion generated by dissolving a salt of the above-described compound in water or a solvent.
In the present specification, a substituent that does not specify substitution or non-substitution (the same applies to a linking group) means that the group may have an arbitrary substituent as long as a desired effect is achieved. . This is also the same for compounds that do not specify substitution or non-substitution.
Further, in the present specification, when simply referred to as “substituent”, a group selected from the following substituent group T may be mentioned unless otherwise specified. In addition, when only a substituent having a specific range is described (for example, when only described as “alkyl group”), a corresponding group of the following substituent group T (in the above case, an alkyl group) The preferred range in FIG.
In the present specification, when the number of carbon atoms of a certain group is defined, this number of carbons means the total number of carbon atoms in the group. That is, when this group has a further substituent, it means the total number of carbon atoms including this substituent.
In this specification, when a certain group can adopt a non-cyclic skeleton and a cyclic skeleton, unless otherwise specified, the certain group includes a non-cyclic skeleton group and a cyclic skeleton group. For example, the alkyl group includes a linear alkyl group, a branched alkyl group, and a cyclic (cyclo) alkyl group. When a certain group takes a cyclic skeleton, the lower limit of the number of carbon atoms in the group of the cyclic skeleton is 3 or more, preferably 5 or more, regardless of the lower limit of the number of carbon atoms specifically described in the certain group.
In this specification, the term “(meth) acrylic acid” is used to include both methacrylic acid and acrylic acid. The same applies to “(meth) acrylamide”. In this specification, the term “acrylic acid” is used in a broader sense than usual. That is, “acrylic acid” is used to include all compounds having a structure of R ^A —C (═CR ^B ₂ ) COOH (R ^A and R ^B each independently represents a hydrogen atom or a substituent, provided that , When R ^A is methyl, means methacrylic acid). The same applies to “acrylamide”.

Substituent group T:
An alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms such as methyl group, ethyl group, isopropyl group, tert-butyl group, n-octyl group, n -Decyl group, n-hexadecyl, etc. In the case of a cycloalkyl group, the number of carbon atoms is preferably 3-20, more preferably 3-12, and particularly preferably 3-8. Group, cyclopentyl group, cyclohexyl group, etc.), alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms such as vinyl group, allyl group, 2- Butenyl group, 3-pentenyl group, etc.), alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably -8, for example, propargyl group, 3-pentynyl group, etc.), aryl group (preferably 6-30 carbon atoms, more preferably 6-20, particularly preferably 6-12, for example phenyl group , Biphenyl group, naphthyl group, etc.), amino group (preferably having 0-20 carbon atoms, more preferably 0-10, particularly preferably 0-6, for example, amino group, methylamino group, dimethylamino group) Group, a diethylamino group, a dibenzylamino group, etc.), an alkoxy group (preferably having a carbon number of 1-20, more preferably 1-12, particularly preferably 1-8, such as a methoxy group, an ethoxy group, Butoxy groups, etc.), aryloxy groups (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 6 carbon atoms). 2, for example, a phenyloxy group, 2-naphthyloxy group, etc.), an acyl group (preferably having a carbon number of 1-20, more preferably 1-16, particularly preferably 1-12, for example acetyl Group, benzoyl group, formyl group, pivaloyl group, etc.), alkoxycarbonyl group (preferably having 2-20 carbon atoms, more preferably 2-16, particularly preferably 2-12, such as methoxycarbonyl group, An ethoxycarbonyl group, etc.), an aryloxycarbonyl group (preferably having a carbon number of 7-20, more preferably 7-16, particularly preferably 7-10, such as a phenyloxycarbonyl group). An acyloxy group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 1 carbon atoms). 0, and examples thereof include an acetoxy group and a benzoyloxy group. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 10 carbon atoms such as acetylamino group and benzoylamino group), alkoxycarbonylamino group (preferably Has 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as a methoxycarbonylamino group, and an aryloxycarbonylamino group (preferably 7 to 20 carbon atoms). Preferably it is 7-16, Most preferably, it is 7-12, for example, a phenyloxycarbonylamino group etc. are mentioned, for example, A sulfonylamino group (preferably C1-C20, More preferably, it is 1-16, Especially preferably, 1 to 12, for example, methanesulfonylamino group, benzenesulfonylamino group, etc. ), A sulfamoyl group (preferably having a carbon number of 0 to 20, more preferably 0 to 16, particularly preferably 0 to 12, such as a sulfamoyl group, a methylsulfamoyl group, a dimethylsulfamoyl group, a phenylsulfamoyl group, And a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms such as carbamoyl group, methylcarbamoyl group, diethylcarbamoyl group, phenyl). A carbamoyl group, etc.), an alkylthio group (preferably having a carbon number of 1-20, more preferably 1-16, particularly preferably 1-12, such as a methylthio group, an ethylthio group, etc.), an arylthio. Group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferred Or a sulfonyl group (preferably having a carbon number of 1 to 20, more preferably 1 to 16, and particularly preferably 1 to 12, such as a mesyl group or tosyl). A sulfinyl group (preferably having a carbon number of 1-20, more preferably 1-16, particularly preferably 1-12, such as a methanesulfinyl group, a benzenesulfinyl group). Urethane group, ureido group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, and examples thereof include ureido group, methylureido group, phenylureido group), phosphoric acid. Amido group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms such as diethyl phosphate Amides, phenylphosphoric acid amides and the like can be mentioned. ), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxy group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having a carbon number of 1 to 30, more preferably 1 to 12, and examples of the hetero atom include a nitrogen atom, an oxygen atom and a sulfur atom, and a 5-membered or 6-membered ring or a condensed thereof. Specific examples thereof include imidazolyl, pyridyl, quinolyl, furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, and the like. A silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms; , Trimethylsilyl group, etc. triphenylsilyl group).
These substituents may further have a substituent. Moreover, when there are two or more substituents, they may be the same or different. Further, adjacent substituents may be connected to each other to form a ring.

Hereinafter, the contents of the present invention will be described in detail.
[1. Polarizing plate protective film]
The polarizing plate protective film of the present invention has a cellulose ester layer containing a cellulose ester and a polymer B1 layer containing a polymer B1 containing a repeating unit of the following [a] adjacent to one surface of the cellulose ester layer. doing.
In this polarizing plate protective film, the polymer B1 layer contains, on the surface of the cellulose ester layer, the polymer B1 and a solvent in which fd defined by the following formula I satisfies the following relational expressions [1] and “2”. The composition is applied to form.
Then, a polarizing plate protective film, 85 ° C., the moisture permeability 6 hours under ambient conditions of relative humidity of 85%, indicating a 100 g / ^{m 2} or more 1600 g / ^{m 2} or less.

[A]: Repeating unit in which solubility parameter δt calculated by Hoy method is 13.5 or more and less than 20.0 Relational expression [1] | fd _solvent −fd _cellulose | ≦ 0.050
Relational expression [2] | fd _solvent −fd _polymerB1 | ≦ 0.050
In relational expressions [1] and [2], fd _solvent represents the fd value of the solvent, fd _cellulose represents the fd value of the cellulose ester contained in the cellulose ester layer, and fd _polymerB1 represents the fd value of the polymer B1.
Here, the fd value is defined by the following formula I.
Formula I fd = δd / (δd + δp + δh)
In Formula I, δd, δp, and δh are a term corresponding to the London dispersion force, a term corresponding to the force between dipoles, and a term corresponding to the hydrogen bonding force, respectively, with respect to the solubility parameter δt calculated by the Hoy method. Fd represents the ratio of δd to the sum of δd, δp, and δh.

The polarizing plate protective film of the present invention having the above configuration has low moisture permeability (low moisture permeability) and excellent interlayer adhesion (also simply referred to as adhesion). Even if this polarizing plate protective film is thinned, it can prevent deterioration of the polarizer under high temperature and high humidity conditions by being superimposed on the polarizer.
The reason is not clear, but it is thought as follows.
The above-described deterioration in image quality is considered to be due to the gradual decrease in the iodine content in the polarizer in the case of a polarizer formed of a polyvinyl alcohol resin dyed with iodine. That is, boric acid cross-links are hydrolyzed in the polarizer by moisture penetrating through the polarizing plate protective film, and polyiodide ions (I ₃ ⁻ , I ₅ ⁻ , and higher order valences). Polyiodide ions) and the like are decomposed into monoiodide ions I- ^{and the} like. Therefore, decomposed iodine diffuses into the polarizing plate protective film, and its content decreases.
As described above, the polarizing plate protective film of the present invention includes a layer containing the polymer B1 containing the repeating unit [a], and can effectively suppress moisture permeability. Therefore, it is possible to prevent moisture from penetrating and prevent contact with the polarizer. Even if the polarizer comes into contact with moisture, it is considered that the above-described diffusion of iodines into the layer containing the polymer B1 can be effectively prevented. And this polymer B1 layer is formed with the composition containing the solvent which satisfy | fills a specific relationship with cellulose ester and polymer B1 regarding the above-mentioned fd value so that it may mention later. Thereby, even if it is a case where it provides directly on a cellulose-ester layer, it is thought that the high interlayer adhesiveness with a cellulose-ester layer is shown, maintaining the low water vapor transmission rate of polymer layer B1.

1. First, the structure of the polarizing plate protective film of the present invention will be described.
The polarizing plate protective film of the present invention has a cellulose ester layer and a polymer B1 layer adjacent to at least one surface of the cellulose ester layer.
In the present invention, a layer adjacent to the surface of a certain layer is one of the certain layers without an adhesive layer (adhesive layer) or the like that adheres or adheres both layers between the certain layer and the adjacent layer. It is a layer provided in a state of being in direct contact with the surface of (a laminated or superposed) layer.

If the polarizing plate protective film of this invention has the said laminated structure, another structure will not be specifically limited.
For example, the structure which has the cellulose ester layer 11 and the polymer B1 layer 12 adjacent to one surface of the cellulose ester layer 11 like the polarizing plate protective film 10A shown by FIG. Moreover, the structure which has the polymer B1 layer 12 adjacent to both the surfaces of the cellulose-ester layer 11 like the polarizing plate protective film 10B shown by FIG. Further, as in the polarizing plate protective film 10C shown in FIG. 3, the cellulose ester layer 11, the polymer B1 layer 12 adjacent to one surface of the cellulose ester layer 11, and the polymer B2 adjacent to the surface of the polymer B1 layer And a structure having a layer 13 (also referred to as a polymer B2 layer). In addition, as in the polarizing plate protective film 10D shown in FIG. 4, the both surfaces of the cellulose ester layer 11 have the polymer B1 layer 12 and the polymer B2 layer 13 in this order, and the layers are adjacent to each other. Is mentioned.
In the above structure, each of the polymer B1 layer and the B2 layer may have a laminated structure of two or more layers. Moreover, the polymer B1 layer and B2 layer provided on both surfaces of the cellulose ester layer 11 may be the same or different.

  In the present invention, when the polymer B1 does not contain the repeating unit [b] described later, the polymer B1 and the polymer B1 layer correspond to the polymer B2 and the polymer B2 layer, respectively. do not do. In other words, the polymer B2 is used as a polymer not including the repeating unit [b] with respect to the polymer B1 including the repeating unit [b]. Similarly, the polymer B2 layer is used as a layer containing the polymer B2 not containing the repeating unit [b] with respect to the layer containing the polymer B1 containing the repeating unit [b]. Therefore, when a plurality of layers containing a polymer containing the repeating unit [a] and not containing the repeating unit [b] are laminated, these layers are all polymer B1 layers.

  In the present invention, the polymer B1 layer, the polymer B2 layer, or both layers may be referred to as an iodine diffusion preventing layer. However, the term “iodine diffusion preventing layer” simply means a layer capable of preventing the diffusion of iodines, and is merely used to facilitate understanding of the present invention. The “iodine diffusion preventing layer” includes all layers containing a polymer as defined in the present invention regardless of the degree to which the diffusion of iodines can be prevented. That is, in judging the gist and technical scope of the present invention, the term “iodine diffusion preventing layer” is not considered as an invention specific matter for limiting the present invention.

In the polarizing plate protective film of the present invention, at least the polymer B1 layer is formed using a composition described later. In this case, there is a mixed region (not shown in FIGS. 1 to 6) where the cellulose ester and the polymer B1 are mixed in the vicinity of the boundary between the cellulose ester layer and the polymer B1 layer (near the laminated surface of each layer). This mixed region is included in either the cellulose ester layer or the polymer B1 layer when focusing on the content of the cellulose ester or polymer B1 contained in the region. For example, in the mixed region, a mixed region in which the content of the cellulose ester is 50% by mass or more is included in the cellulose ester layer with respect to 100% by mass in total of the cellulose ester and the polymer B1.
In the polarizing plate protective film of the present invention, the mixed region is formed when the polymer B1 layer is formed. Therefore, even in the polymer B1 layer having a low affinity with the cellulose ester, the cellulose ester and the polymer B1 are mixed in the mixed region, and the interlayer adhesion with the cellulose ester layer is strengthened.
In the present invention, a mixed region where the polymer B1 and the polymer B2 are mixed may be provided in the vicinity of the boundary between the polymer B1 layer and the polymer layer B2. In this case, the interlayer adhesion between the polymer B1 layer and the polymer layer B2 layer is strengthened.
A method for forming the polymer B1 layer and the polymer B2 layer will be described later.

In the present invention, various functional layers specialized for a specific function may be directly provided on the surface of the cellulose ester layer or the iodine diffusion preventing layer. Examples of such a functional layer include a hard coat layer, an antireflection layer, a light scattering layer, an antifouling layer, and an antistatic layer. The functional layer may serve as a plurality of functions.
In the present invention, the functional layer is preferably provided directly on the surface of the cellulose ester layer from the viewpoint of enhancing the effects of the present invention.

2. Iodine Diffusion Prevention Layer In the present invention, “polymer B1 layer” or “polymer B2 layer” means that the entire polymer layer (total mass) constituting the layer contains 50% by mass or more of polymer B1 or polymer B2 described later. It means the layer to do. Here, the content of each polymer in the entire polymer layer is preferably 60% by mass or more, more preferably 70% by mass or more, still more preferably 80% by mass or more, and particularly preferably 85% by mass or more. The higher the content of the polymer B1 or the polymer B2, the better the adhesion with the cellulose ester layer or the like, which is preferable. Therefore, the content of each polymer B1 or B2 in the entire polymer layer may be 100% by mass, and is usually 99% by mass or less. When the content of the polymer in the polymer layer is not 100% by mass, the remainder may include a resin other than the polymers B1 and B2 described later.
Two or more kinds of polymers may be used as the polymer B1 or the polymer B2, respectively. That is, polymers having different composition ratios and / or molecular weights may be used in combination. In this case, the total amount of each polymer falls within the above range.

There is no restriction | limiting in particular in the film thickness of an iodine diffusion prevention layer, 1-25 micrometers is preferable, 1-20 micrometers is more preferable, and 1-15 micrometers is especially preferable.
When the iodine diffusion preventing layer has the polymer B1 layer and the polymer B2 layer, the film thicknesses of the polymer B1 layer and the polymer B2 layer are not particularly limited as long as the total film thickness is within the above range. For example, the film thickness of the polymer B1 layer is preferably 0.1 to 24 μm, more preferably 0.2 to 19 μm, and particularly preferably 0.5 to 14 μm. Moreover, 0.1-24 micrometers is preferable, as for the film thickness of polymer B2 layer, 0.2-19 micrometers is more preferable, and 0.5-14 micrometers is especially preferable.

Below, polymer B1 and polymer B2 which comprise the iodine diffusion prevention layer of this invention are each demonstrated.
<2-1: Polymer B1>
The polymer B1 used in the present invention contains the following repeating unit [a].
[A]: Repeating unit having a solubility parameter δt calculated by the Hoy method of 13.5 or more and less than 20.0

In the present invention, the solubility parameter δt is determined for Amorphous Polymers literature ^{"Properties of Polymers 3 rd, ELSEVIER} , (1990)" in "2) Method of Hoy (1985, 1989) " column of page 214 to 220 of δt is assumed and is calculated according to the description in the above column of the above document. The unit of δt is usually ^{(J /} cm ^{3) 1/2} or (cal ^/ cm ³⁾ uses a ^1/2, in the present invention, use of (cal ^/ cm ^{3) 1/2.}

  The polymer B1 is not particularly limited as long as it has a repeating unit satisfying the above [a], but a (meth) acrylic resin can be preferably used.

((Meth) acrylic resin)
In the present invention, the (meth) acrylic resin includes a methacrylic resin in addition to the acrylic resin. The (meth) acrylic resin includes a polymer of a (meth) acrylic acid compound, a copolymer of these compounds, a polymer of a (meth) acrylic acid ester, or a copolymer of these esters. . The (meth) acrylic resin may contain a ring structure formed by a cyclization reaction in the main chain after polymerizing the compound. Examples of the polymer having such a structure include a polymer having a lactone ring, a polymer having a glutaric anhydride ring, and a glutarimide ring-containing polymer.

  The repeating unit of the (meth) acrylic resin is not particularly limited as long as it has the solubility parameter δt in the above range. The (meth) acrylic resin preferably has a repeating unit derived from a (meth) acrylic acid ester as a repeating unit.

The (meth) acrylic acid ester is not particularly limited, and examples thereof include methyl acrylate, ethyl acrylate, n-butyl acrylate, isobutyl acrylate, t-butyl acrylate, cyclohexyl acrylate, and benzyl acrylate. Acrylic acid esters, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, cyclohexyl methacrylate, methacrylic acid esters such as benzyl methacrylate, and the like. May be used alone or in combination of two or more. Among these, methyl methacrylate is particularly preferable from the viewpoint of excellent heat resistance and transparency.
The repeating unit derived from the (meth) acrylic acid ester is preferably 50 to 100% by mass, more preferably 70 to 100% in order to sufficiently exert the effect of the present invention with respect to the total mass of the repeating unit of the acrylic resin. 100 mass%, More preferably, it is 80-100 mass%, Most preferably, it is 90-100 mass%.

The glass transition temperature Tg of the acrylic resin is preferably in the range of 80 to 120 ° C. This glass transition temperature Tg is measured using a differential scanning calorimeter (DSC), and in the present invention, the measuring method described below can be used. In addition to the (meth) acrylic resin powder itself, the measurement sample may be a powder obtained by scraping the polymer B1 layer from the polarizing plate protective film. In addition, when using the powder which scraped off the polymer B1 layer, you may remove (purify) components other than polymer B1 as needed.
<Measuring method of glass transition temperature Tg>
With a differential scanning calorimeter (X-DSC7000, manufactured by IT Measurement Control Co., Ltd.), 20 mg of a measurement sample is placed in a measurement pan, and this is heated from 30 ° C. to 120 ° C. at a rate of 10 ° C./min in a nitrogen stream. Hold for 15 minutes and then cool to 30 ° C. at −20 ° C./min. Thereafter, the temperature is raised again from 30 ° C. to 250 ° C., and the temperature at which the baseline starts to deviate from the low temperature side is defined as the glass transition temperature Tg.

  The weight average molecular weight of the (meth) acrylic resin is not particularly limited. For example, the lower limit of the weight average molecular weight of the resin is preferably 10,000 or more, preferably 15,000 or more, and more preferably 30,000 or more from the viewpoint of the surface properties of the film. On the other hand, the upper limit of the weight average molecular weight of the (meth) acrylic resin is preferably 2,000,000 or less, more preferably 1,800,000 or less, and more preferably 1,500,000 or less, from the viewpoint of film forming properties. Is more preferably 1,000,000 or less, and most preferably 500,000 or less. The molecular weight can be measured by the method described in Examples described later.

  The (meth) acrylic resin may be appropriately synthesized or a commercially available product may be used. Although it does not specifically limit as a commercially available (meth) acrylic resin, For example, dialnal BR83, BR80, BR85, and BR88 (all are brand names, the product made from Mitsubishi Rayon), or 80N (brand name, Asahi Kasei Delpet) is. preferable.

In addition to the repeating unit [a], the polymer B1 preferably further has the following repeating unit [b].
[B]: Repeating unit having a solubility parameter δt calculated by the Hoy method of 20.0 or more and 26.0 or less With such a configuration, the affinity between the polymer B1 and the cellulose ester is further increased. It is possible to secure stronger adhesion between the ester layer and the iodine diffusion preventing layer.

  The polymer B1 containing the repeating unit [b] in addition to the repeating unit [a] will be described below.

The repeating unit [b] is not particularly limited as long as it has a solubility parameter δt in the above range, but is preferably a repeating unit represented by the following general formula (1). Since the β-ketoester structure in the repeating unit represented by the following general formula (1) has good affinity with the cellulose ester, the adhesion between the cellulose ester layer and the iodine diffusion preventing layer can be enhanced.
General formula (1)

In the general formula (1), R ¹ represents a hydrogen atom, an aliphatic group, an aromatic group or a heterocyclic group, and the aliphatic group, aromatic group and heterocyclic group may have a substituent. L is a single bond, a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group, —C (═O) —, —O—, —N (R ² ) — or those The combination of is shown. The divalent aliphatic group, divalent aromatic group and divalent heterocyclic group may have a substituent. R ² represents a hydrogen atom or an alkyl group.

Examples of the aliphatic group for R ¹ include an alkyl group, an alkenyl group, an alkynyl group, and a cycloalkyl group. Among them, an alkyl group having 1 to 6 carbon atoms is preferable, and methyl is more preferable.
The aromatic group in the above R ^1, but are not limited to, phenyl, naphthyl group, and a biphenyl group, a phenyl group is preferred among them.
The heterocyclic group in R ¹ is not particularly limited, and examples thereof include a pyridyl group, a pyrrolidyl group, a piperidyl group, a piperazol group, a pyrrolyl group, a morpholino group, a thiamorpholino group, an imidazolyl group, a pyrazolyl group, a pyrrolidonyl group, and a piperidonyl group. Among them, a morpholino group and a pyridyl group are preferable.

R ¹ in the general formula (1) is preferably a hydrogen atom or an aliphatic group, more preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, particularly preferably a hydrogen atom or methyl. It is more particularly preferable.

  Examples of the substituent that the aliphatic group, aromatic group or heterocyclic group may have include an alkyl group having 1 to 6 carbon atoms (for example, methyl, ethyl, isopropyl, tert-butyl, cyclopentyl, cyclohexyl). ), An alkenyl group having 2 to 6 carbon atoms (for example, vinyl, allyl, 2-butenyl, 3-pentenyl), an alkynyl group having 2 to 6 carbon atoms (for example, propargyl group, 3-pentynyl group), an amino group (for example, Amino group, methylamino group, dimethylamino group, diethylamino group, dibenzylamino group), alkoxy group (for example, methoxy group, ethoxy group, butoxy group), aryloxy group (for example, phenyloxy group, 2-naphthyloxy group), Acyl group (for example, acetyl group, benzoyl group, formyl group, pivaloyl group), alkoxycarbonyl Group (for example, methoxycarbonyl group, ethoxycarbonyl group), aryloxycarbonyl group (for example, phenyloxycarbonyl group), acyloxy group (for example, acetoxy group, benzoyloxy group), acylamino group (for example, acetylamino group, benzoylamino group), Alkoxycarbonylamino group (for example, methoxycarbonylamino group), aryloxycarbonylamino group (for example (phenyloxycarbonylamino group), sulfonylamino group (for example, methanesulfonylamino group, benzenesulfonylamino group), sulfamoyl group (for example, sulfamoyl group, Methylsulfamoyl group, dimethylsulfamoyl group, phenylsulfamoyl group), carbamoyl group (eg carbamoyl group, methylcarbamoyl group, diethylcarbamo) Group, phenylcarbamoyl group), alkylthio group (eg methylthio group, ethylthio group), arylthio group (eg phenylthio group), sulfonyl group (eg mesyl group, tosyl group), sulfinyl group (eg methanesulfinyl group, benzenesulfinyl group) Ureido group (eg ureido group, methylureido group, phenylureido group), phosphoric acid amide group (eg diethylphosphoric acid amide, phenylphosphoric acid amide), hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, Bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, heterocyclic group (eg imidazolyl group, pyridyl group, quinolyl group, furyl group, piperidyl) Group, morpholino group, A benzoxazolyl group, a benzimidazolyl group, a benzthiazolyl group) or a silyl group (for example, a trimethylsilyl group or a triphenylsilyl group). Among them, methyl and fluoromethyl are preferable.

L in the general formula (1) is a single bond, a divalent aliphatic group, a divalent aromatic group, a divalent heterocyclic group, -C (= O)-, -O-, -N (R ² )-or a combination thereof, and the divalent aliphatic group, divalent aromatic group, and divalent heterocyclic group may have a substituent.
L is preferably a divalent aliphatic group, a divalent aromatic group, —C (═O) —, or L ¹ -L ² — (wherein ^one of L ¹ and L ² is —C (═O) —, —O—, —N (R ² ) — or a combination thereof is shown, and the other represents a divalent aliphatic group, a divalent aromatic group or a divalent heterocyclic group. The divalent aliphatic group, divalent aromatic group and divalent heterocyclic group may have a substituent, and R ² represents a hydrogen atom or an alkyl group. Here, in -L ¹ -L ^2-, L ¹ is linked to the main chain.
The L is more preferably -L ¹ -L ^2- .
In the above L, L ¹ is —C (═O) —, —O—, —N (R ² ) —, or a combination thereof, and L ² is a divalent aliphatic group or divalent aromatic. A group or a divalent heterocyclic group is particularly preferable.

The divalent aliphatic group in L is preferably an alkylene group or an alkynyl group, more preferably an alkylene group which may have a substituent having 1 to 5 carbon atoms, and an ethylene group. More particularly preferred.
Although it does not specifically limit as a bivalent aromatic group in said L, A C6-C12 aromatic group is preferable, It is preferable that they are a phenylene group and a naphthylene group, The phenylene which may have a substituent It is more preferably a group, and an unsubstituted phenylene group is particularly preferable.
The divalent heterocyclic group in L is not particularly limited, but includes pyridylene group, pyrrolidylene group, piperidylene group, piperazylene group, pyrrolylene group, morpholinylene group, thiamorpholinenine group, imidazolylene group, pyrazolylene group, pyrrolidonylene group, A piperidonylene group can be mentioned, and among these, a morpholinylene group is preferable.
Examples of the substituent that the divalent aliphatic group, divalent aromatic group and divalent heterocyclic group may have include an alkyl group and a halogen group, and among them, an alkyl group Is preferable, an alkyl group having 1 to 6 carbon atoms is more preferable, and a methyl group is particularly preferable.

L ¹ is preferably —C (═O) —, —O—, —N (R ² ) —, or a combination thereof. Examples of —C (═O) —, —O—, —N (R ² ) —, or combinations thereof include —C (═O) —, —O—, —C (═O) —O—, — ^{O-C (= O) -} , - N (R 2) -C (= O) -, - C (= O) -N (R 2) -, ^{or, -N (R 2) -C (} = O ) —N (R ² ) — is preferred. Furthermore, L ¹ is more preferably —C (═O) —O— or —C (═O) —N (R ² ) —, and particularly preferably —C (═O) —O—. preferable.
L ² is preferably a divalent aliphatic group, a divalent aromatic group or a divalent heterocyclic group, an alkylene group optionally having a substituent having 1 to 5 carbon atoms, or A phenylene group which may have a substituent having 1 to 5 carbon atoms is more preferable, an alkylene group which may have a substituent having 1 to 5 carbon atoms is more preferable, ethylene More preferably, it is a group.
The preferred ranges of the divalent aliphatic group, divalent aromatic group and divalent heterocyclic group in L ¹ and L ² are the divalent aliphatic group and divalent aromatic group in L. It is the same as the preferable range of the group and divalent heterocyclic group.

A preferred combination of R ¹ and L in the general formula (1) is that R ¹ in the general formula (1) is a hydrogen atom or methyl, L is a divalent aliphatic group, a divalent aromatic group,- In this embodiment, C (═O) — or L ¹ -L ² —.
More preferably, R ¹ in the general formula (1) is a hydrogen atom or methyl, and L is L ¹ -L ^2- .
More preferably, R ¹ in the general formula (1) is a hydrogen atom or methyl, L ¹ is —C (═O) —O—, and L ² has a substituent having 1 to 5 carbon atoms. It is an embodiment that is an alkylene group that may be present.
Particularly preferred is an embodiment in which R ¹ in the above general formula (1) is a hydrogen atom or methyl, L ¹ is —C (═O) —O—, and L ² is an ethylene group.
In each of the above combinations, methyl is preferable for R ¹ in the general formula (1).

R ² represents a hydrogen atom or an alkyl group.
R ² is preferably a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, more preferably a hydrogen atom or methyl, and particularly preferably a hydrogen atom.

一般式（２）中、Ｒ^１及びＬは、一般式（１）におけるＲ^１及びＬと同義であり、好ましい範囲も一般式（１）におけるＲ^１及びＬと同一である。 As the compound (monomer) capable of deriving the repeating unit represented by the general formula (1), a compound represented by the following general formula (2) is preferable.
General formula (2)

In General Formula (2), R ¹ and L are synonymous with R ¹ and L in General Formula (1), and a preferable range is also the same as R ¹ and L in General Formula (1).

  The compound represented by the general formula (2) is more preferably ethyl acetoacetate or ethyl acetoacetate, and still more preferably ethyl acetoacetate.

  The compounds represented by the following general formula (2) are listed below, but the present invention is not limited to these specific examples.

In the present invention, the polymer B1 containing the repeating unit [a] and containing the repeating unit [b] is represented by the general formula (2) as a compound capable of deriving the repeating unit [b]. One or two or more of the represented compounds can be used in combination. Among them, it is preferable to use ethyl acetoacetate methacrylate, ethyl acetoacetate acrylate or a mixture thereof.
Here, the polymer containing the repeating unit [a] and the repeating unit [b] is a combination of the above compound capable of deriving the repeating unit [a] and the compound represented by the general formula (2). It becomes a polymer. That is, it may be a copolymer of the compound capable of deriving the repeating unit [a] and only one kind of the compound represented by the general formula (2). It is also possible to use a copolymer obtained by using two or more compounds represented by the above general formula (2) and the above compound capable of deriving. There is no particular limitation on the composition ratio of the repeating unit corresponding to each compound of the copolymer obtained by using two or more compounds represented by the general formula (2).

  The compound represented by the general formula (2) used in the present invention can be obtained as a commercial product or synthesized with reference to known literature.

The polymer B1 may contain other repeating units in addition to the repeating unit [a] and the repeating unit [b]. That is, in the present invention, the compound capable of deriving the repeating unit [a], the compound represented by the general formula (2), if necessary, and at least one other repeating unit are copolymerized. The polymer obtained can be used.
The compound that leads to the other repeating unit is not particularly limited as long as it can be copolymerized with the compound that can lead to the repeating unit of the above [a] and the compound represented by the general formula (2). Ethylenically unsaturated compounds are preferred. As the ethylenically unsaturated compound, other ethylenically unsaturated compounds other than the above compound capable of deriving the repeating unit [a] and the compound represented by the above general formula (2) are preferable.
These may be used alone or in combination of two or more with the above compound capable of deriving the repeating unit [a] and, if necessary, with the compound represented by the above general formula (2). .

(Content of repeating unit in polymer B1)
As long as the polymer B1 has the repeating unit [a], the content of the repeating unit is not particularly limited.
From the viewpoint of obtaining a polarizing plate protective film having low moisture permeability, the molar amount of the repeating unit [a] in the total molar amount of the repeating units constituting the polymer B1 is preferably 100 mol% or less. . When the polymer B1 has a repeating unit other than the repeating unit of [a], the molar amount of the repeating unit of [a] in the total molar amount of the repeating unit constituting the polymer B1 is preferably 10 mol% or more, 20 mol% or more is more preferable, and 30 mol% or more is still more preferable. Moreover, 80 mol% or less is preferable, 70 mol% or less is more preferable, and 60 mol% or less is still more preferable.

  From the viewpoint of further improving the affinity between the polymer B1 layer and the cellulose ester layer and obtaining a polarizing plate protective film excellent in interlayer adhesion, the above [b] occupying in the total molar amount of the repeating units constituting the polymer B1. Is preferably 10 mol% or more, more preferably 20 mol% or more, and even more preferably 30 mol% or more. The molar amount of the repeating unit [b] in the total molar amount of the repeating units constituting the polymer B1 is preferably 90 mol% or less, more preferably 80 mol% or less, and even more preferably 70 mol% or less.

  In the polymer B1, the molar amount of the repeating unit represented by the general formula (1) in the total molar amount of the repeating unit [b] is preferably 0.1 to 100 mol%. More preferably, it is -100 mol%.

  When the polymer B1 contains the repeating unit of [b], the content of the repeating unit of [a] and the content of the repeating unit of [b] are in the molar ratio [repeat of [[a]]. Unit] / [Repeating unit of [b]] = 95/5 to 10/90 is preferably satisfied, [Repeating unit of [a]] / [Repeating unit of [b]] = 95/5 to 30/70. It is more preferable to satisfy [Repeating unit of [[a]] / [Repeating unit of [b]] = 92/8 to 50/50, and [Repeating unit of [a]] / [[[ b] repeating unit] = 90/10 to 60/40 is more preferable, and [[a] repeating unit] / [[b] repeating unit] = 90/10 to 75/25 is satisfied. Further preferred.

  When the polymer B1 has the other repeating unit, the content of the repeating unit [a] and the content of the repeating unit [b] in the total molar amount of the repeating unit constituting the polymer B1. The total amount is preferably 5% by mass or more, more preferably 10% by mass or more, still more preferably 20% by mass or more, and particularly preferably 50% by mass or more. In the polymer B1, the molar amount of the repeating unit [a] and the repeating unit [b] is preferably 100 mol% or less in total, the repeating unit [a] and the repeating unit [b] It is also preferable that the unit consists of units.

(Synthesis method of polymer B1)
The method for synthesizing the polymer B1 is not particularly limited, and a conventionally known method can be widely used. Examples thereof include a radical polymerization method, an anionic polymerization method, and a cation polymerization method using a compound that derives the repeating unit. It is done. Examples of the initiator used in the radical polymerization method include azo compounds or peroxides, and more specifically, azobisisobutyronitrile (AIBN), azoisobutyric acid diester derivatives, benzoyl peroxide, and the like. It is done. The polymerization solvent is not particularly limited. For example, an aromatic hydrocarbon solvent such as toluene or chlorobenzene, a halogenated hydrocarbon solvent such as dichloroethane or chloroform, an ether solvent such as tetrahydrofuran or dioxane, an amide solvent such as dimethylformamide, methanol, etc. Alcohol solvents, ester solvents such as methyl acetate or ethyl acetate, ketone solvents such as acetone, cyclohexanone or methyl ethyl ketone, or water. Depending on the selection of the solvent, solvent polymerization that polymerizes in a homogeneous system, precipitation polymerization that precipitates the produced polymer, and emulsion polymerization that polymerizes in a micelle state can also be performed.

(Molecular weight of polymer B1)
The weight average molecular weight of the polymer B1 is preferably 10,000 to 2,000,000, more preferably 20,000 to 1,800,000, and 30,000 to 1,800,000. More preferably, it is particularly preferably 30,000 to 1,500,000. The molecular weight can be measured by the method described in Examples described later.

<2-2: Polymer B2>
When the polymer B2 is used, as described above, the polarizing plate protective film of the present invention has, for example, the structure shown in FIG. 3 or FIG. As a result, stronger adhesion between the cellulose ester layer and the iodine diffusion preventing layer can be secured, and deterioration of polarization performance in a high temperature and high humidity environment when incorporated in a polarizing plate can be effectively suppressed. become.
The reason is not clear, but it can be considered as follows. In the case of having a polymer B2 layer as the iodine diffusion preventing layer, the polymer B1 layer contains the polymer B1 having the repeating unit [a] and the repeating unit [b]. The two types of repeating units in the polymer B1 function in a well-balanced manner. As a result, in addition to the interlayer adhesion between the cellulose ester layer and the polymer B1 layer, the interlayer adhesion between the iodine diffusion preventing layers, that is, the polymer B1 layer and the polymer B2 layer is also improved. In addition, it is possible to further suppress deterioration of polarization performance in a high-temperature and high-humidity environment when incorporated in a polarizing plate.

Polymer B2 contains the following repeating unit [a] and does not contain the following repeating unit [b]. In the present invention, the fact that the repeating unit of [b] is not included does not exclude the repeating unit of [b] which is inevitably present, for example, in the total molar amount of the repeating unit constituting the polymer B2. It means that the content of the repeating unit [b] is 1% by mass or less.
[A]: Repeating unit with solubility parameter δt calculated by Hoy method of 13.5 or more and less than 20.0 [b]: Repeating unit with solubility parameter δt calculated by Hoy method of 20.0 or more and 26.0 or less

The repeating unit contained in the polymer B2 is synonymous with the repeating unit of [a] described in the polymer B1, and the preferred range is also the same.
Similarly, the repeating unit not containing the polymer B2 has the same meaning as the repeating unit [b] described above, and the preferred range is also the same.
As long as the polymer B1 has the repeating unit [a], the content of the repeating unit is not particularly limited.

From the viewpoint of obtaining a polarizing plate protective film with low moisture permeability, the molar amount of the repeating unit [a] in the total molar amount of the repeating units constituting the polymer B2 is preferably 100 mol% or less. .
The polymer B2 may have the other repeating unit. In this case, in the total molar amount of the repeating units constituting the polymer B2, the content of the repeating unit of [a] is preferably 5% by mass or more, more preferably 10% by mass or more, More preferably, it is at least 30% by mass, and particularly preferably at least 30% by mass. The polymer B2 is also preferably in the form of the repeating unit [a].

(Molecular weight of polymer B2)
The lower limit of the weight average molecular weight of the polymer B2 is preferably 10,000 or more, more preferably 20,000 or more, and particularly preferably 30,000 or more from the viewpoint of the surface properties of the film. On the other hand, the lower limit of the weight average molecular weight of the polymer B2 is preferably 2,000,000 or less, more preferably 1,800,000 or less, and further preferably 1,500,000 or less, from the viewpoint of the surface properties of the film. The molecular weight can be measured by the method described in Examples described later.

(Synthesis method of polymer B2)
The method for synthesizing the polymer B2 is not particularly limited, and conventionally known methods can be widely employed. Examples thereof include various synthesis methods described in the method for synthesizing the polymer B1.

<2-3: Additive>
The polymer B1 layer and the B2 layer may each contain an additive as long as the effects of the present invention are not impaired.
As an additive, the additive used for the cellulose-ester layer mentioned later is mentioned.

Examples of the additive include a fluoroaliphatic group-containing polymer (sometimes abbreviated as “fluorine polymer”). When this polymer is contained, the surface smoothness of the iodine diffusion preventing layer can be improved. The fluoroaliphatic group-containing polymer is preferably a polymer having a perfluoroalkyl group having 4 or more carbon atoms or a fluoroalkyl group having 4 or more carbon atoms and —CF ₂ H in the side chain. Specifically, reference can be made to the descriptions in paragraphs [0191] to [0211] of JP2012-214004A, the contents of which are incorporated herein.

In the fluoropolymer, the amount of monomer units derived from the fluoroaliphatic group-containing monomer represented by the general formula [2] described in paragraph [0193] of JP2012-214004A is the total monomer of this fluoropolymer. It is preferable that it is 10 mass% or more with respect to unit amount, More preferably, it is 40 mass% or more.
The amount of the monomer unit derived from the monomer represented by the general formula [3] described in paragraph [0193] of JP2012-214004A in the fluoropolymer is 90% with respect to the total monomer unit amount of the fluoropolymer. It is preferable to use less than mass%, more preferably less than 60 mass%.

The preferred weight average molecular weight of the fluoropolymer is preferably from 3,000 to 100,000, more preferably from 6,000 to 80,000, and even more preferably from 8,000 to 60,000.
Here, the weight average molecular weight was measured using a TPCgel GMHxL, TSKgel G4000HxL, and TSKgel G2000HxL columns (both manufactured by Tosoh Corporation, trade name) with a solvent THF (tetrohydrofuran) and polystyrene by differential refractometer detection. The molecular weight expressed in terms of conversion. The molecular weight is calculated from the peak area of 300 or more components.

  When the iodine diffusion preventing layer contains a fluorine-based polymer, from the viewpoint of drying and suppression of occurrence of surface failure, the total solid content in the composition (coating liquid) for forming each polymer layer (each The content (% by mass) of the fluoropolymer in the polymer layer is preferably 0.001% by mass to 5% by mass, and more preferably 0.005% to 2.0% by mass.

Examples of additives other than the above include fine particles. The fine particles are not particularly limited, but fine oxide particles such as silicon, titanium, zirconium or aluminum, or crosslinked particles such as polyethylene, polystyrene, poly (meth) acrylate or polydimethylsiloxane, or SBR (Styrene-). Examples thereof include organic fine particles such as crosslinked rubber fine particles such as Butadiene Rubber (styrene-butadiene rubber) or NBR (Acrylonitrile-Butadiene Rubber). When the iodine diffusion preventing layer contains the crosslinked fine particles, it is possible to prevent generation of scratches during conveyance or sticking of the film in a roll form.
The average particle size of the fine particles is preferably 1 nm to 20000 nm. Further, the shape of the fine particles can be used without any particular limitation, such as a spherical shape, a rod shape, a needle shape or a plate shape. The amount of fine particles added is preferably 60% by volume or less, and more preferably 40% by volume or less in each polymer layer.

3. Cellulose ester layer The cellulose ester layer (also referred to as cellulose ester film) constituting the polarizing plate protective film of the present invention is a layer containing 50% by mass or more of cellulose ester in the layer. 60 mass% or more is preferable, as for content of the cellulose ester in a cellulose-ester layer, 70 mass% or more is more preferable, 80 mass% or more is further more preferable, and 85 mass% or more is still more preferable. The higher the content of the cellulose ester in the cellulose ester layer, the more preferable is that the adhesiveness with the iodine diffusion preventing layer can be maintained. Accordingly, the upper limit of the content of the cellulose ester is not particularly limited, but is preferably 99% by mass or less, more preferably 96% by mass or less, still more preferably 95% by mass or less, and particularly preferably 92% by mass or less. . In this case, the remainder excluding the cellulose ester includes, for example, an additive described later.
The cellulose ester layer may contain other resins in the layer, and examples of the polymer B1 or B2 are preferable. When the cellulose ester layer contains the polymer B1 or B2, interlayer adhesion with the polymer layer can be further improved.

<3-1: Cellulose ester>
The cellulose ester used for the cellulose ester film of the present invention will be described.
The cellulose ester can be used without particular limitation as long as it is a cellulose ester used for the production of a cellulose ester film.
The glucose unit which comprises cellulose and has β-1,4 bonds has free hydroxy groups at the 2nd, 3rd and 6th positions. The cellulose ester is a polymer (polymer) obtained by esterifying a part of these hydroxy groups with an esterifying agent or the like.
Examples of cellulose include cotton linter and wood pulp (hardwood pulp, softwood pulp), and the like. Any cellulose obtained from any raw material cellulose can be used, and in some cases, a mixture may be used. For example, Maruzawa and Uda, “Plastic Materials Course (17) Fibrous Resin”, Nikkan Kogyo Shimbun (published in 1970) and JSHI published technical bulletin No. 2001-1745 (page 7) To page 8) can be used.
As a cellulose ester, the well-known cellulose ester used for manufacture of a cellulose-ester film can be used without a restriction | limiting at all. Of these, cellulose acylate is preferably used.

(Cellulose acylate)
As the cellulose acylate used in the present invention, a known cellulose acylate used for producing a cellulose ester film can be used without any limitation.
The acyl substitution degree (hereinafter, sometimes simply referred to as “substitution degree”) indicates the degree of acylation of the hydroxy group of cellulose located at the 2-position, 3-position and 6-position, and is 2 for all glucose units. When the hydroxy groups at the 3rd, 6th and 6th positions are all acylated, the total degree of acyl substitution is 3. For example, if all glucose units are all acylated at position 6, the total degree of acyl substitution is 1. Similarly, the total acyl substitution degree is 1 when all of any one of the 6-position and 2-position is acylated in each glucose unit in all hydroxy groups of all glucose.
That is, the degree of substitution indicates the degree of acylation, assuming that 3 is when all the hydroxy groups in the glucose molecule are all acylated.
The degree of substitution of cellulose acylate is described in Tezuka et al., Carbohydrate. Res. , 273, 83-91 (1995), or according to the method prescribed in ASTM-D817-96.

  The total acyl substitution degree of the cellulose acylate used in the present invention is preferably 1.50 or more and 3.00 or less, more preferably 2.00 to 2.97, from the viewpoint of moisture permeability. It is more preferably 30 or more and less than 2.97, and particularly preferably 2.30 to 2.95.

There is no restriction | limiting in particular in the acyl group of the cellulose acylate used for this invention, The form which has 1 type of acyl groups may be sufficient, and the form which has 2 or more types of acyl groups may be sufficient. The cellulose acylate that can be used in the present invention preferably has an acyl group having 2 or more carbon atoms as a substituent. The acyl group having 2 or more carbon atoms is not particularly limited, and may be an aliphatic acyl group or an aromatic acyl group. The cellulose acylate substituted with these acyl groups is, for example, an alkyl carbonyl ester, alkenyl carbonyl ester, aromatic carbonyl ester, or aromatic alkyl carbonyl ester of cellulose, each having a further substituted group. Also good.
Specific examples of the acyl group having 2 or more carbon atoms include acetyl, propionyl, butanoyl, heptanoyl, hexanoyl, octanoyl, decanoyl, dodecanoyl, tridecanoyl, tetradecanoyl, hexadecanoyl, octadecanoyl, isobutanoyl, tert-butanoyl, cyclohexanecarbonyl Oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like. Among these, acetyl, propionyl, butanoyl, dodecanoyl, octadecanoyl, tert-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, and cinnamoyl are preferable, acetyl, propionyl, and butanoyl are more preferable, and acetyl is particularly preferable.

  The cellulose acylate preferably has an acyl group having 2 to 4 carbon atoms as a substituent. When two or more kinds of acyl groups are used, it is preferable that one of them is an acetyl group. These cellulose acylates can produce a solution having a preferable solubility, and in particular, a non-chlorine organic solvent can be used to produce a good solution. Furthermore, it becomes possible to produce a solution having a low viscosity and good filterability.

  Cellulose acetate using only an acetyl group as the acyl group of cellulose acylate can be suitably used in the present invention, and the total acyl substitution degree of this cellulose acetate is 2.00 to 2.00 in terms of moisture permeability and optical properties. It is preferably 3.00, more preferably 2.20 to 3.00, still more preferably 2.30 to 3.00, still more preferably 2.30 to 2.97. It is particularly preferably 2.30 to 2.95.

A mixed fatty acid ester having two or more kinds of acyl groups can also be preferably used as the cellulose acylate in the present invention. Among them, the acyl group of the mixed fatty acid ester preferably includes an acetyl group and an acyl group having 3 to 4 carbon atoms. When the mixed fatty acid ester contains an acetyl group as an acyl group, the degree of acetyl substitution is preferably less than 2.5 and more preferably less than 1.9. On the other hand, when the acyl group having 3 to 4 carbon atoms is contained, the substitution degree of the acyl group having 3 to 4 carbon atoms is preferably 0.1 to 1.5, and preferably 0.2 to 1.2. Is more preferable, and 0.5 to 1.1 is particularly preferable.
Moreover, the mixed acid ester which has a fatty-acid acyl group and a substituted or unsubstituted aromatic acyl group as described in Paragraph [0023]-[0038] of Unexamined-Japanese-Patent No. 2008-20896 can also be used preferably.

  In the present invention, two types of cellulose esters or cellulose acylates having one or both of an ester group and a degree of substitution can be used in combination. In this case, you may form as a laminated structure which consists of a different cellulose ester by the co-casting method etc. which are mentioned later.

The cellulose ester or cellulose acylate used in the present invention preferably has a degree of polymerization of 250 to 800, more preferably 300 to 600. In addition, the number average molecular weight of the cellulose ester or cellulose acylate used in the present invention is preferably 40000 to 230,000, more preferably 60000 to 230,000, and most preferably 75000 to 200000.
The degree of polymerization can be determined by dividing the number average molecular weight measured in terms of polystyrene by gel permeation chromatography (GPC) by the molecular weight of the glucopyranose unit of cellulose ester or cellulose acylate.

The cellulose ester used in the present invention can be synthesized by a conventional method. For example, cellulose acylate can be synthesized using an acid anhydride or acid chloride as an acylating agent. When the acylating agent is an acid anhydride, an organic acid (for example, acetic acid) or methylene chloride is used as a reaction solvent. Further, a protic catalyst such as sulfuric acid can be used as the catalyst. When the acylating agent is an acid chloride, a basic compound can be used as a catalyst. In general industrial production of cellulose acylate, an organic acid (acetic acid, propionic acid, butyric acid, etc.) or an acid anhydride (acetic anhydride, propionic anhydride, butyric anhydride, etc.) corresponding to the desired acyl group in cellulose is used. Is used to esterify the hydroxy group.
For example, a cellulose derived from cotton linter or wood pulp is used as a raw material, and this is activated with an organic acid such as acetic acid and then esterified with an organic acid having a desired structure in the presence of a sulfuric acid catalyst. Acylate can be obtained. When an organic acid anhydride is used as the acylating agent, cellulose is generally esterified using an excess amount of the organic acid anhydride relative to the amount of hydroxy groups present in the cellulose.
Cellulose acylate can also be synthesized, for example, by the method described in JP-A-10-45804.

  The cellulose ester film preferably contains 5 to 99% by mass of a cellulose ester as a resin from the viewpoint of moisture permeability, more preferably 20 to 99% by mass, and particularly preferably 50 to 95% by mass.

<3-2: Other additives>
The cellulose ester layer may contain an additive as long as the effects of the present invention are not impaired. Examples of the additive include known plasticizers, organic acids, dyes, polymers, retardation adjusting agents, ultraviolet absorbers, antioxidants, and matting agents. About these, the description of paragraph number [0062]-[0097] of Unexamined-Japanese-Patent No. 2012-155287 can be referred to, These content is integrated in this-application specification. Examples of the additive include a peeling accelerator, an organic acid, and a polyvalent carboxylic acid derivative. About these, the description of WO2015 / 005398 paragraph [0212]-[0219] can be referred to, These content is integrated in this-application specification. Furthermore, examples of the additive include a radical scavenger, a deterioration inhibitor, and a barbituric acid compound, which will be described later.
The content of additives (when the cellulose ester film contains two or more additives, the total content thereof) is preferably 50 parts by mass or less with respect to 100 parts by mass of the cellulose ester, 30 More preferably, it is 5 parts by mass or less, and still more preferably 5 to 30 parts by mass.

(Plasticizer)
One preferred additive is a plasticizer. By adding a plasticizer to the cellulose ester film, the hydrophobicity of the cellulose ester film can be increased. This point is preferable from the viewpoint of reducing the moisture permeability of the cellulose ester film. When such a plasticizer is used, when the cellulose ester film is used as a protective film for a polarizer (referred to as a polarizing plate protective film), display unevenness of an image display device due to humidity may be less likely to occur. This is preferable because it is possible.

Although it does not specifically limit as a plasticizer, The polyvalent ester compound (henceforth "polyhydric alcohol ester plasticizer") of a polyhydric alcohol, and a polycondensation ester compound (henceforth "polycondensation ester plasticizer") Or a carbohydrate compound (hereinafter also referred to as “carbohydrate derivative plasticizer”). For polyhydric alcohol ester plasticizers, paragraphs [0081] to [0098] of WO 2015/005398, for polycondensed ester plasticizers, paragraphs [0099] to [0122] of the same publication, carbohydrate derivative plasticizers. Can be referred to paragraphs [0123] to [0140] of the same publication, the contents of which are incorporated herein.
The molecular weight of the plasticizer is preferably 3000 or less, more preferably 1500 or less, and still more preferably 1000 or less, from the viewpoint of obtaining the above-described effect by adding it satisfactorily. The molecular weight of the plasticizer is, for example, 300 or more, preferably 350 or more, from the viewpoint of low volatility. In the case of multimeric plasticizers, the molecular weight is the number average molecular weight.

The content of the plasticizer is preferably 1 to 20 parts by mass, and 2 to 15 parts by mass with respect to 100 parts by mass of the cellulose ester, from the viewpoint of achieving both the effect of adding the plasticizer and the suppression of precipitation of the plasticizer. It is more preferable to set it as 5-15 mass parts.
Two or more plasticizers may be used in combination. Also when using 2 or more types together, the specific example and preferable range of content are the same as the above.

(Antioxidant)
One preferable additive may include an antioxidant. Regarding the antioxidant, the description of paragraphs [0143] to [0165] of International Publication No. 2015/005398 can be referred to, and the contents thereof are incorporated in the present specification.

(Radical scavenger)
One preferred additive may include a radical scavenger. Regarding the radical scavenger, the description in paragraphs [0166] to [0199] of International Publication No. 2015/005398 can be referred to, and the contents thereof are incorporated in the present specification.

(Deterioration inhibitor)
As one of preferable additives, a deterioration preventing agent can be mentioned. Regarding the deterioration preventing agent, the description in paragraphs [0205] to [0206] of International Publication No. 2015/005398 can be referred to, and the contents thereof are incorporated in the present specification.

(Barbituric acid compound)
The cellulose ester film can also contain a compound having a barbituric acid structure (barbituric acid compound). A barbituric acid compound is a compound which can express various functions to a cellulose-ester film by adding this compound. For example, a barbituric acid compound is effective for improving the hardness of a cellulose ester film. The barbituric acid compound is also effective in improving the durability of a polarizing plate provided with a cellulose ester film containing this compound against light, heat or humidity. About the barbituric acid compound which can be used for the said cellulose-ester film, the description of international publication 2015/005398 paragraph [0029]-[0060] can be referred to, These content is integrated in this-application specification.

<3-3: Physical properties of cellulose ester film>
The cellulose ester film of the present invention preferably has the following physical properties or characteristics.
(Film thickness)
The average film thickness of the cellulose ester film can be appropriately determined according to the use, but is preferably, for example, 10 to 100 μm, more preferably 15 to 80 μm, and further preferably 25 to 60 μm. . By setting it to 10 μm or more, the handling property when producing a web-like film is improved, which is preferable. Moreover, by setting it as 100 micrometers or less, it is easy to respond to a humidity change and it is easy to maintain an optical characteristic.
Moreover, when a cellulose-ester film has a laminated structure of three or more layers, 3-70 micrometers is preferable and, as for the film thickness of a core layer (base layer), 5-60 micrometers is more preferable. The film thicknesses of the first skin layer (also referred to as air surface layer or air side surface layer) and the second skin layer (also referred to as support layer or support side surface layer) in the case of the three-layer structure are both 0.5. -20 μm is preferred, 0.5-10 μm is more preferred, and 0.5-3 μm is even more preferred. The core layer is a layer located inside in the laminated structure, and in the case of a three-layer structure, the core layer is an intermediate layer, and both skin layers are layers located outside in the laminated structure or the three-layer structure.

(width)
Although the said cellulose-ester film can be suitably determined according to a use, For example, it is preferable that film width is 700-3000 mm, it is more preferable that it is 1000-2800 mm, and it is especially preferable that it is 1470-2500 mm.

4). Moisture permeability of polarizing plate protective film The moisture permeability of the polarizing plate protective film is 100 to 1600 g / m ² per 6 hours. When the moisture permeability per 6 hours is less than 100 g / m ² , drying in the polarizing plate production process is slow and productivity is lowered. On the other hand, if it exceeds 1600 g / m ² , deterioration of the polarizer may not be effectively suppressed when used as a protective film for the polarizer.
In the present invention, the moisture permeability per 6 hours is preferably 150~1200g / ^{m 2,} more preferably from 200 to 1000 g / ^{m 2,} and particularly preferably 300 to 800 g / ^{m 2.} By controlling the moisture permeability within the above range, the productivity of the polarizing plate is high, and deterioration of the polarizer can be effectively suppressed when used as a protective film for the polarizer.
The moisture permeability in the polarizing plate protective film of the present invention is a value calculated by the following method based on “moisture-proof packaging material moisture permeability test method (cup method)” of JIS Z 0208 (1976).
The polarizing plate protective film was cut into 60 mm × 60 mm, subjected to a temperature of 85 ° C. and 85% relative humidity, the mass of water vapor passing through the cut films to 6 hours was measured, the mass per surface area 1 m ² of cut films It can obtain | require as a converted value.
The mass of water vapor is measured by the mass change of the moisture absorbent (anhydrous calcium chloride).

5. Manufacturing method of polarizing plate protective film The manufacturing method of the polarizing plate protective film of this invention is demonstrated.

The polarizing plate protective film includes, for example, a step of applying a composition (formation liquid) for forming a polymer B1 layer on at least one surface of the cellulose ester layer after preparing the cellulose ester layer by a method described later. It is manufactured by the method of including.
The composition for forming the polymer B1 layer contains polymer B1 and a solvent in which fd defined by the following formula I satisfies the following relational expressions [1] and [2]. Thereby, the interlayer adhesiveness of a cellulose-ester layer and polymer B1 layer can be made stronger. In particular, by the above method, the above-mentioned mixed region can be formed in the vicinity of the boundary between the cellulose ester layer and the polymer B1 layer, and the effect of improving the interlayer adhesion is increased.
Although the thickness of the said mixing area | region is not specifically limited, It can set suitably according to the ease of melt | dissolution or swelling of the cellulose ester by a coating solvent (henceforth solubility or swelling property), the drying speed of a solvent, etc.
The thickness of the mixed region in the cellulose ester layer or the polymer B1 layer is derived from the cellulose ester and the polymer B1 by performing time-of-flight secondary ion mass spectrometry of the film cross section near the boundary between the cellulose ester layer and the polymer B1 layer. It can be measured by the distribution of fragment ions.

<5-1: Manufacturing Method of Cellulose Ester Layer>
The manufacturing method of the cellulose-ester layer used for the manufacturing method of the polarizing plate protective film of this invention is demonstrated.

The cellulose ester film is not particularly limited, and is preferably produced by, for example, a melt casting method or a solution casting method (solvent casting method). In consideration of volatilization and decomposition of the additive, More preferably it is manufactured.
As the melt film forming method, a production method such as a T-die method is preferably used, and a simultaneous coextrusion method is particularly preferably used. As the solution casting method, it is preferable to use a lamination casting method such as a co-casting method, a sequential casting method, or a coating method, which will be described later. It is particularly preferable to use it from the viewpoint of stable production and production cost reduction.
US Pat. Nos. 2,336,310, 2,367,603, 2,492,078, and 2,492,977 describe examples of film production utilizing the solution casting method. 2,492,978, 2,607,704, 2,739,069 and 2,739,070, British Patent Nos. 640731 and 736892. Nos. 45-4554, 49-5614, JP-A-60-176834, JP-A-60-203430, and JP-A-62-115035 can be referred to. .

(Casting)
The solution casting method includes a method of uniformly extruding the prepared dope from a pressure die onto a metal support, and a doctor that adjusts the film thickness with a blade of the dope once cast on a metal support. There are a method using a blade and a method using a reverse roll coater which adjusts with a reverse rotating roll, and a method using a pressure die is preferred. The pressure die includes a coat hanger type and a T die type, and any of them can be preferably used. In addition to the methods listed here, it can be carried out by various methods for casting a cellulose ester solution known in the art, and each condition is set in consideration of differences in the boiling point of the solvent used. can do.

As the metal support, one that runs endlessly is preferable, and a drum whose surface is mirror-finished by chrome plating or a stainless steel belt (which may be called a band) whose surface is mirror-finished is used. Although there is no restriction | limiting in particular about the material of the said metal support body, It is more preferable that it is a product made from SUS (for example, SUS316).
One or two or more pressure dies may be installed above the metal support. Preferably one or two are installed. When two or more are installed, the dope amount to be cast may be divided into various ratios for each die, or the dope may be fed to the dies from each of a plurality of precision quantitative gear pumps at each ratio. The temperature of the dope (resin solution) used for casting is preferably −10 to 55 ° C., more preferably 25 to 50 ° C. In that case, all solution temperatures in the process may be the same or different at different points in the process. If they are different, the temperature may be a desired temperature just before casting.

When the cellulose ester film is a multilayer, it is preferable to use a lamination casting method such as a co-casting method, a sequential casting method or a coating method, and particularly a simultaneous co-casting method (also referred to as a simultaneous multi-layer co-casting method). It is particularly preferable from the viewpoint of stable production and production cost reduction.
When producing a cellulose ester film by a co-casting method and a sequential casting method, first, a cellulose ester solution (also referred to as a dope) for each layer is prepared, and this solution is cast on a support.
In the co-casting method (multi-layer simultaneous casting), first, a casting dope for each layer (which may be three layers or more) is provided on a casting support (band or drum) from a separate slit or the like. The dope is extruded using a casting die that can be extruded at the same time, and the layers are cast simultaneously. It is a casting method in which after casting, the film is peeled off from the support after an appropriate time and dried to form a film. By using a co-casting die, for example, a total of three layers: a surface layer two layers formed from a surface layer dope on a casting support, and a core layer composed of a core layer dope sandwiched between these surface layers. It can be extruded and cast simultaneously on a support. FIG. 8 is a schematic diagram (partially enlarged view) showing an example of co-casting. The co-casting according to the example shown in FIG. 8 will be further described in an example described later.

In the sequential casting method, a casting dope for the first layer is first extruded from a casting die on a casting support, cast, and dried or dried without being dried. The dope for casting for two layers is extruded from a casting die, and if necessary, the dope is successively casted to the third layer or more, laminated, and peeled off from the support after an appropriate time. And dried to form a cellulose ester film.
In the coating method, generally, a core layer is formed into a film by a solution casting method, and a coating solution that is a target cellulose ester solution is applied to the surface layer, followed by drying to form a cellulose ester having a laminated structure. A film can be produced.

(Stretching)
The cellulose ester film is also preferably stretched after casting and drying. As described above, the cellulose ester film preferably has a degree of orientation in the thickness direction within a certain range, but the orientation degree in the thickness direction can be increased by stretching treatment. The stretching direction of the cellulose ester film may be either a film transport direction (MD (Machine Direction) direction) or a direction (TD (Transverse Direction) direction) orthogonal to the transport direction. Considering the subsequent polarizing plate processing process, the TD direction is preferable. The stretching process may be performed a plurality of times in two or more stages.

Methods for stretching in the TD direction are described in, for example, JP-A-62-115035, JP-A-4-152125, JP-A-2842211, JP-A-298310, and JP-A-11-48271. Yes. In the case of stretching in the TD direction, the film can be stretched by conveying the film while holding it with a tenter and gradually widening the width of the tenter. Further, after the polymer film is dried, it can be stretched using a stretching machine (preferably uniaxial stretching using a long stretching machine).
In the case of stretching in the MD direction, for example, it can be performed by adjusting the speed of the film transport roller to make the winding speed faster than the film peeling speed.

The stretching ratio of the cellulose ester film (meaning the ratio of the stretching amount to the dimension before stretching) is preferably 1% or more and 100% or less, more preferably 5% or more and 60% or less, and more preferably 10% or more and 40% or less. Particularly preferred.
In particular, in the stretching in the width direction, the stretching ratio is preferably 5% or more and 30% or less, and more preferably 8% or more and 20% or less.
Further, the film may be stretched in both the transport direction and the width direction. In that case, the stretch ratio in the transport direction is 1% or more and 20% or less, and the stretch ratio in the width direction is 5% or more and 30% or less. It is preferable that the draw ratio in the conveyance direction is 1% or more and 8% or less, and the draw ratio in the width direction is 10% or more and 20% or less.

The stretching process may be performed in the middle of the film forming process, or the raw film that has been formed and wound may be stretched, but in the production method of the present invention, the support is used in a state containing a residual solvent. It is preferable to exfoliate and stretch, that is, stretch in the middle of the film forming process.
The amount of the residual solvent at the time of peeling from the support is preferably 10 to 100% by mass, and more preferably 15 to 60% by mass.
Here, the residual solvent amount can be calculated by the following equation.
Residual solvent amount (% by mass) = {(MN) / N} × 100
In the formula, M represents the mass of the cellulose ester film before drying, and N represents the mass when the cellulose ester film before drying is dried at 110 ° C. for 3 hours.

(Dry)
In the manufacturing method of the said cellulose-ester film, from the viewpoint of retardation development, including the process of drying the said cellulose-ester film, and the process of extending | stretching the cellulose-ester film after drying at the temperature of Tg-10 degreeC or more. preferable.

  In general, the dope is dried on the metal support for producing the cellulose ester film by applying hot air from the surface side of the metal support (drum or belt), that is, from the surface of the web on the metal support. Method, method of applying hot air from the back of the drum or belt, contact the temperature-controlled liquid from the back of the belt or drum opposite the dope casting surface, and heat the drum or belt by heat transfer to control the surface temperature There is a back surface liquid heat transfer method, and the back surface liquid heat transfer method is preferable. The surface temperature of the metal support before casting may be any number as long as it is not higher than the boiling point of the solvent used for the dope. However, in order to promote drying and to lose fluidity on the metal support, the temperature should be set to 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent. Is preferred. Note that this is not the case when the casting dope is cooled and peeled off without drying.

(Peeling)
The method for producing the cellulose ester film preferably includes a step of peeling the dope film from the metal support. There is no restriction | limiting in particular about the peeling method in the manufacturing method of the said cellulose-ester film, When a well-known method is used, peelability can be improved. It can also peel in the above-mentioned extending | stretching process in the film forming process.

  The film thickness may be adjusted by adjusting the solid content concentration contained in the dope, the slit gap of the die base, the extrusion pressure from the die, the metal support speed, and the like so as to obtain a desired thickness.

  The length of the cellulose ester film obtained as described above is preferably wound at 100 to 10,000 m per roll, more preferably 500 to 7000 m, and still more preferably 1000 to 6000 m. When winding, it is preferable to give knurling to at least one end, the knurling width is preferably 3 mm to 50 mm, more preferably 5 mm to 30 mm, and the height is preferably 0.5 to 500 μm, more preferably 1 to 200 μm. is there. This may be a single push or a double push.

  In general, in a large screen display device, since the contrast reduction and coloration in an oblique direction become remarkable, the cellulose ester film is particularly suitable for use in a large screen liquid crystal display device. When used as an optical compensation film for a large-screen liquid crystal display device, for example, the film width is preferably set to 1470 mm or more. In addition, the polarizing plate protective film of the present invention is produced not only in the form of a film piece cut into a size that can be incorporated into a liquid crystal display device as it is, but also in a long shape by continuous production. The film of the aspect wound up in the shape is also included. The polarizing plate protective film of the latter mode is stored and transported in that state, and is cut into a desired size and used when it is actually incorporated into a liquid crystal display device or bonded to a polarizer or the like. Similarly, it is cut into a desired size when it is actually incorporated into a liquid crystal display device after being bonded to a polarizer or the like made of a polyvinyl alcohol film or the like that has been made into a long shape. Used. As one mode of the optical compensation film wound up in a roll shape, a mode in which the roll length is rolled up to 2500 m or more can be mentioned.

  Thus, the cellulose ester film used as a base material layer in the said manufacturing method can be produced.

<5-2: Formation of polymer B1 layer>
Next, a method for forming the polymer B1 layer on the cellulose ester layer will be described.
The polymer B1 layer can be formed by applying the following composition on the cellulose ester layer. Thereby, a cellulose-ester layer and polymer B1 layer can be laminated | stacked by high interlayer adhesiveness.
Details of the application method of the composition will be described later.
The composition is preferably dried after application.

(Composition for forming polymer B1 layer)
In the present invention, the polymer B1 layer is formed using the following composition. A composition (also referred to as an iodine diffusion preventing layer forming composition) B1 for forming a polymer B1 layer used in this method is composed of a polymer B1 and fd defined by the following formula I: And a solvent satisfying the relational expression [2] and, if necessary, an additive described later.

When the solubility or swelling property with respect to the cellulose ester is too low, the formation of the mixed region may be insufficient and sufficient interlayer adhesion may not be exhibited. On the other hand, if the solubility or swellability is too high, after the solvent is removed by drying, the cellulose ester and the polymer B1 may be phase-separated and the mixed region may become brittle, and sufficient interlayer adhesion will not be exhibited. Sometimes.
From the above viewpoint, as the solvent contained in the composition B1, a solvent in which fd defined by the following formula I satisfies the following relational expressions [1] and [2] is used.
Formula I fd = δd / (δd + δp + δh)
In Formula I, δd, δp, and δh are a term corresponding to the London dispersion force, a term corresponding to the force between dipoles, and a term corresponding to the hydrogen bonding force, respectively, in the solubility parameter δt calculated by the Hoy method. Fd represents the ratio of δd to the sum of δd, δp, and δh.
Relational expression [1] | fd _solvent -fd _cellulose | ≦ 0.050
Relational expression [2] | fd _solvent −fd _polymerB1 | ≦ 0.050
In relational expressions [1] and [2], fd _solvent represents the fd value of the solvent, fd _cellulose represents the fd value of the cellulose ester contained in the cellulose ester layer, and fd _polymerB1 represents the fd value of the polymer B1. .
When | fd _solvent -fd _cellulose | calculated by the relational expression [1] exceeds 0.050, swelling or dissolution of the cellulose ester by the solvent becomes insufficient, and adhesiveness decreases. On the other hand, if | fd _solvent -fd _polymerB1 | calculated by the relational expression [2] exceeds 0.050, the polymer B1 layer after coating and drying becomes brittle and adhesion decreases.

The solvent contained in this composition will not be specifically limited if the said relational expressions [1] and [2] are satisfy | filled. This solvent preferably satisfies the relational expression [1-1] and the relational expression [2-1] in terms of interlayer adhesion.
Relational expression [1-1] | fd _solvent -fd _cellulose | ≦ 0.040
Relational expression [2-1] | fd _solvent -fd _polymerB1 | ≦ 0.040
In the relational expression [1-1] and the relational expression [2-1], d _solvent , fd _cellulose, and fd _polymerB1 are respectively synonymous with the relational expressions [1] and [2].

In addition to satisfying the relational expression [1] or [1-1] and the relational expression [2] or [2-1], the solvent further includes the following relational expression [1-2] and relational expression [ Those satisfying at least one of 2-2] are more preferable.
Relational expression [1-2] | fd _solvent -fd _cellulose | ≦ 0.020
Relational expression [2-2] | fd _solvent -fd _polymerB1 | ≦ 0.040
In relation [1-2] and equation _{[2-2], d solvent, fd} cellulose and _{fd PolymerB1,} respectively, as defined in the above equation [1] and [2].

  The lower limits of the relational expressions [1] and [2] are both 0, but preferably 0.001.

In the present invention, the fd value when two or more solvents are used in combination is calculated by the following equation.
(Fd value of mixed solvent) = Σ (wi · fdi)
Here, wi represents the mass fraction of the i-th solvent, and fdi represents the fd value of the i-th solvent.

In the present invention, the fd value when two or more kinds of polymers B1 are used in combination is calculated by the following equation.
(Fd value of mixed polymer B1) = Σ (wi · fdi)
Here, wi represents the mass fraction of the i-th polymer B1, and fdi represents the fd value of the i-th polymer B1.

When the polymer B1 has two or more kinds of repeating units, the fd value of the polymer B1 in the relational expression [2] is calculated by δd, δp, and δh obtained by the following formula.
(Δd value of polymer B1) = Σ (mi · δdi)
Here, mi represents the mole fraction of the i-th repeating unit, and δdi represents the δd value of the i-th repeating unit.
(Δp value of polymer B1) = Σ (mi · δpi)
Here, mi represents the mole fraction of the i-th repeating unit, and δpi represents the δp value of the i-th repeating unit.
(Δh value of polymer B1) = Σ (mi · δhi)
Here, mi represents the mole fraction of the i-th repeating unit, and δhi represents the δh value of the i-th repeating unit.

In the present invention, when the cellulose ester layer contains two or more cellulose esters, the fd value of the cellulose ester is calculated as follows.
(Fd value of cellulose ester) = Σ (wi · fdi)
Here, wi represents the mass fraction of the i-th cellulose ester, and fdi represents the fd value of the i-th cellulose ester.

  When selecting the solvent to be used, fd represented by the above formula I is calculated for each of the cellulose ester or polymer B1 to be used and the solvent.

− The term δd corresponding to the London dispersion force −
Term corresponds to the London dispersion force δd is calculated for Amorphous Polymers according to "2) Method of Hoy (1985,1989)" column of page 214 to 220 of the literature ^{"Properties of Polymers 3 rd, ELSEVIER} , (1990)" Is calculated according to the description in the above column of the above document.

− The term δp corresponding to the force between dipoles −
The method of calculating the term δd corresponding to dipole-dipole forces, document ^{"Properties of Polymers 3 rd, ELSEVIER} , (1990)" of 214 to 220 pages of "2) Method of Hoy (1985,1989)" column according to It means δp required for Amorphous Polymers and is calculated according to the description in the above column of the above document.

− The term δh corresponding to the hydrogen bonding force −
The method of calculating the term δh corresponding to hydrogen bonding forces, document ^{"Properties of Polymers 3 rd, ELSEVIER} , (1990)" Amorphous in "2) Method of Hoy (1985,1989)" column of page 214 to 220 of It means δh required for Polymers and is calculated according to the description in the above column of the above document.

  Using the δd, δp, and δh calculated as described above, fd of the solvent, the polymer B1, and the cellulose ester is calculated according to Formula I. Thereby, it can be judged whether the solvent to be used satisfies the relational expressions [1] and [2].

The solubility parameter δt is a physical property index having the following relationship with respect to the term δd corresponding to the London dispersion force, the term δp corresponding to the dipole force, and the term δh corresponding to the hydrogen bond force.
δt ² = δd ² + δp ² + δh ²

The cellulose ester has a glucopyranose ring portion having a small polarity and an ester portion having a high polarity and capable of forming hydrogen bonds. The present inventors found that the swelling or solubility of cellulose ester in the solvent corresponds to the term δd corresponding to the London dispersion force, the affinity to the glucopyranose ring part, the term δp corresponding to the force between dipoles, and the hydrogen bonding force. The sum of the terms δh corresponds to the affinity for the ester moiety, and we thought it important to balance the two. Furthermore, with respect to the polymer B1 of the present invention such as polymethyl methacrylate, the solubility in a solvent can be adjusted by balancing the affinity for the hydrocarbon group part and the affinity for the polar group and the hydrogen bonding group part. I thought that. Based on this hypothesis, the inventors focus on the contribution rate fd of the London dispersion force to the sum of the term δd corresponding to the London dispersion force, the term δp corresponding to the dipole force, and the term δh corresponding to the hydrogen bond force. As a result, a correlation was found between the adhesion of the polarizing plate protective film of the present invention or the effect of improving the durability of the polarizing plate.
The present inventors consider this as follows. When the above composition is applied onto the cellulose ester layer, the polymer B1 and the cellulose ester present on the surface of the laminated interface and in the vicinity thereof are used by using a solvent having an fd value similar to that of the polymer B1 and the cellulose ester. Each dissolves in a solvent. As a result, the interaction between the polymer B1 and the cellulose ester is increased through the solvent at the laminated interface, and in addition, a mixed region of the polymer B1 and the cellulose ester is formed in the vicinity of the interface between the two layers. ing.

Although it does not specifically limit as a solvent which can satisfy | fill said relational expression [1] and relational expression [2], An organic solvent is mentioned, 1 type can be used individually or multiple types can be used together. Among these, it is preferable to select and use a ketone solvent, an acetate solvent, and a hydrocarbon solvent that satisfy the above relational expression [1] and relational expression [2].
Although it does not specifically limit as a ketone solvent, For example, acetone, MEK (methyl ethyl ketone), MiBK (methyl isobutyl ketone), etc. are mentioned. Although it does not specifically limit as an acetate solvent, For example, methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, or butyl acetate is mentioned. Although it does not specifically limit as a hydrocarbon solvent, For example, toluene or a cyclohexane is mentioned.

  In the composition, the mass ratio between the polymer B1 and the solvent is not particularly limited, but the polymer B1 is 3 to 3 with respect to the total amount of the solvent exhibiting the fd value satisfying the relational expression [1] and the relational expression “2”. It is preferable to contain 50 mass%. By setting it as such mass ratio, the composition excellent in manufacture aptitude can be obtained.

  The polymer B1 contained in the composition liquid is as described above.

As long as the effects of the present invention are not impaired, the composition liquid may contain the above-described polymer B1, other resins, and various additives.
This composition preferably further includes a material (binder) for forming the active energy ray-cured layer from the viewpoint of promoting drying of the solvent after application. Such a binder is not particularly limited, and ordinary binders can be used.

(Application of iodine diffusion preventing layer forming composition B1)
The method for applying the iodine diffusion preventing layer forming composition B1 is not particularly limited, and a normal method can be adopted. For example, in addition to the method for producing a cellulose ester film having a multilayer structure as described above, a coating method and the like can be mentioned. From the viewpoint of productivity, the coating method is preferable, and the spray coating method is more preferable among the coating methods.

− Application of iodine diffusion preventing layer forming composition B1 −
The coating method of the iodine diffusion preventing layer forming composition B1 is not particularly limited, and a normal method can be adopted. In addition to the melt film forming method and the solution film forming method (solvent casting method), after preparing the cellulose ester layer by the above-described method, the polymer layer B1 can also be formed by various coating methods. As various coating methods, for example, dip coating method, air knife coating method, curtain coating method, roller coating method, wire bar coating method, gravure coating method, extrusion coating method (die coating method) (see US Pat. No. 2,681,294) ) Or a known method such as a micro gravure coating method is used. Among these, the micro gravure coating method is preferable. Moreover, it is although it does not specifically limit about the conveyance speed at the time of application | coating, It is preferable to apply | coat on conditions with a conveyance speed of 1-100 m / min.

(Drying of the iodine-type diffusion preventing layer forming composition B1)
Although the drying conditions after application are not particularly limited, when drying is fast (evaporation of the solvent is fast), the time during which the cellulose ester and the polymer B1 can be mixed becomes short, and the thickness of the mixing region becomes thin. Therefore, the drying conditions take into consideration the thickness of the formed mixed region, for example, the temperature of the drying air, the solvent content in the drying air, the thickness of the composition after application, the molecular weight of the solvent, the boiling point of the solvent, etc. It is preferable to set appropriately. For example, the drying temperature is preferably selected from the range of 25 to 140 ° C. and the drying time of 30 to 1000 seconds.
In this way, the polymer B1 layer is formed on the cellulose ester layer.

<5-3: Formation of polymer B2 layer>
Next, if necessary, a polymer B2 layer is formed on the surface of the polymer B1 layer formed as described above on the side opposite to the cellulose ester layer.
The polymer B2 layer can be formed by applying a composition (also referred to as an iodine diffusion preventing layer forming composition) B2 for forming the polymer B2 layer on the surface.
The application method of this composition B2 is not specifically limited, The same method as the application method of composition B1 for iodine diffusion prevention layer formation is mentioned, A coating method is preferable.
Composition B2 is preferably dried after application.
The iodine diffusion preventing layer forming composition B2 contains the polymer B2, the solvent, and, if necessary, the additives described above.

The solvent contained in the iodine diffusion preventing layer forming composition B2 is not particularly limited, and there is no limitation regarding fd defined by Formula I such as the above relational expression. As such a solvent, various organic solvents can be used. As an organic solvent, a ketone solvent, an acetate solvent, or a hydrocarbon solvent is mentioned preferably, for example, The same kind as the solvent contained in the composition B1 for iodine diffusion prevention layer formation is mentioned. In addition to these, chain aliphatic hydrocarbon solvents such as n-pentane, n-hexane, n-heptane, liquid paraffin or mineral spirits, or cyclopentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, ethyl An alicyclic hydrocarbon solvent such as cyclohexane, diethylcyclohexane, decahydronaphthalene, dicycloheptane, tricyclodecane, hexahydroindene or cyclooctane can also be used.
When the same kind of solvent as the solvent contained in the composition for forming an iodine diffusion preventing layer B1 is used, the interaction between the polymer B1 and the polymer B2 is increased during the formation of the polymer B2 layer. A mixed region of the polymer B1 and the polymer B2 is formed in the vicinity. Thereby, the polymer B1 layer and the polymer B2 layer can be laminated with strong interlayer adhesion.

  Any of the above methods for applying the iodine diffusion preventing layer forming composition B2 is the same as the above method for applying the iodine diffusion preventing layer forming composition B1. Also in a preferable coating method, the coating method (conditions) and drying method (conditions) of the iodine diffusion preventing layer forming composition B2 are the same as the coating method and drying method of the iodine diffusion preventing layer forming composition B1. .

  In this way, the polymer B2 layer can be formed on the polymer B1 layer.

  In the present invention, in the case where an iodine diffusion preventing layer is provided on both sides of the polarizer, in the same manner as in “5-2: Formation of polymer B1 layer” and “5-3: Formation of polymer B2 layer”, An iodine diffusion preventing layer can be formed on each side.

[2. Polarizer]
1. Polarizing plate The polarizing plate of the present invention comprises at least one polarizer and the polarizing plate protective film of the present invention. The polarizing plate of the present invention having the polarizing plate protective film of the present invention has strong adhesion between the polarizer and the polarizing plate protective film, effectively prevents deterioration of the polarizer, and exhibits high polarizer durability.
Below, the structure and performance of a polarizing plate, a polarizer, etc. are demonstrated.

2. Polarizer The polarizer is not particularly limited as long as it comprises at least a dichroic dye and a resin, and those usually used for polarizing plates can be used. For example, a film obtained by immersing and stretching a polyvinyl alcohol film in an iodine solution can be used. When using a polarizer obtained by immersing and stretching a polyvinyl alcohol film in an iodine solution, for example, using an adhesive, the saponification surface of the cellulose ester layer in the laminate is bonded to at least one surface of the polarizer. Can do.

3. Shape and structure of polarizing plate The shape of the polarizing plate of the present invention is not only a polarizing plate in the form of a film piece cut into a size that can be incorporated into a display device as it is, but also produced in a long shape by continuous production. In addition, a polarizing plate of an aspect wound in a roll shape (for example, an aspect having a roll length of 2500 m or more or 3900 m or more) is also included. In order to use for a large-screen liquid crystal display device, the width of the polarizing plate is preferably 1470 mm or more.

  In general, a polarizing plate in which both sides are protected by sandwiching a polarizer with a polarizing plate protective film is widely used as the polarizing plate, but the polarizing plate of the present invention protects the polarizing plate on at least one surface of the polarizer. Other configurations are not particularly limited as long as the film is included. For example, as shown in FIG. 5, there are a polarizer 16 and a polarizing plate 15 </ b> A having at least one polarizing plate protective film 10 </ b> A of the present invention only on one surface of the polarizer 16. Moreover, although not shown in figure, the polarizing plate which has the polarizing plate protective film of this invention on both surfaces of a polarizer is also mentioned.

Furthermore, the polarizing plate of the present invention may have a film on the surface on which the polarizing plate protective film of the present invention is not provided in that the surface of the polarizer is protected and optically compensated. Although it does not specifically limit as such a film, In addition to the said surface protection and optical compensation, the cycloolefin film containing a cycloolefin polymer is mentioned preferably at the point which shows high moisture resistance.
An example of a polarizing plate having a cycloolefin film is a polarizing plate 15B shown in FIG. This polarizing plate 15B has the polarizing plate protective film 10A of the present invention on one surface of the polarizer 16, and the cycloolefin film 17 on the other surface.

  Examples of the cycloolefin polymer include (1) a polymer containing a structural unit derived from a norbornene compound, (2) a polymer containing a structural unit derived from a monocyclic olefin compound other than the norbornene compound, (3) A polymer containing a structural unit derived from a cyclic conjugated diene compound, (4) a polymer containing a structural unit derived from a vinyl alicyclic hydrocarbon compound, and a structure derived from each compound of (1) to (4) Examples include hydrides of polymers containing units. In the present invention, the polymer containing a structural unit derived from a norbornene compound and the polymer containing a structural unit derived from a monocyclic olefin compound include a ring-opening polymer of each compound.

  Although it does not specifically limit as a cycloolefin polymer, The polymer which has a structural unit derived from the norbornene compound represented by the following general formula (A-II) or (A-III) is preferable. A polymer having a structural unit represented by the following general formula (A-II) is an addition polymer of a norbornene compound, and a polymer having a structural unit represented by the following general formula (A-III) is a norbornene compound. It is a ring-opening polymer.

In general formula, m is an integer of 0-4, and 0 or 1 is preferable.
R ^{3 to} R ⁶ each independently represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms.
In the present invention, the hydrocarbon group is not particularly limited as long as it is a group composed of a carbon atom and a hydrogen atom, and examples thereof include an alkyl group, an alkenyl group, an alkynyl group, and an aryl group (aromatic hydrocarbon group). Among these, an alkyl group or an aryl group is preferable.
X ² and X ³ , Y ² and Y ³ are each independently a hydrogen atom, a hydrocarbon group having 1 to 10 carbon atoms, a halogen atom, a hydrocarbon group having 1 to 10 carbon atoms substituted with a halogen atom,- _{^{(CH 2) nCOOR 11, -}} (CH 2) nOCOR 12, - (CH 2) nNCO, - (CH 2) nNO 2, - (CH 2) nCN, - (CH 2) nCONR 13 R 14, - (CH _{^{2) nNR 13 R 14, -}} (CH 2) nOZ, - (CH 2) nW, or the ^{X 2} and ^{Y 2} or ^{X 3} and ^{Y 3} bonded to form together, (- _{CO) 2} O or ( _-CO) represents a 2 ^{NR 15.}
Here, R ^{11 to} R ¹⁵ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, Z represents a hydrocarbon group or a hydrocarbon group substituted with a halogen, and W represents Si ( R ¹⁶ ) _p D _(3-p) (R ¹⁶ represents a hydrocarbon group having 1 to 10 carbon atoms, D is a halogen atom, —OCOR ¹⁷ or —OR ¹⁷ (R ¹⁷ is a hydrocarbon having 1 to 10 carbon atoms) Group), p is an integer of 0-3.
n is an integer of 0 to 10, preferably 0 to 8, and more preferably 0 to 6.

In General Formula (A-II) or (A-III), R ^{3 to} R ⁶ are each preferably a hydrogen atom or —CH _{3, and} more preferably a hydrogen atom in terms of moisture permeability.
X ² and Y ² are each preferably a hydrogen atom, —CH ₃ , or —C ₂ H _{5, and} more preferably a hydrogen atom in terms of moisture permeability.
X ³ and Y ³ are each preferably a hydrogen atom, a halogen atom (especially a chlorine atom) or — (CH ₂ ) nCOOR ¹¹ (particularly —COOCH ₃ ), and more preferably a hydrogen atom in terms of moisture permeability.
Other groups are appropriately selected.
In the general formula (A-II) or (A-III), m is 0 or 1, and R ^{3 to} R ⁶ , X ^{2 to} X ³ and Y ^{2 to} Y ³ are all hydrogen atoms. Particularly preferred.

  The polymer having the structural unit represented by the general formula (A-II) or (A-III) may further contain at least one structural unit represented by the following general formula (AI).

In the general formula, R ¹ and R ² each independently represent a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, and X ¹ and Y ¹ each independently represent a hydrogen atom or a carbon atom having 1 to 10 carbon atoms. hydrocarbon group, a halogen atom, a hydrocarbon group having 1 to 10 carbon atoms substituted with a halogen _{^{atom, - (CH 2) nCOOR 11}} , - (CH 2) nOCOR 12, - (CH 2) nNCO, - (CH 2 ^{_{) nNO 2, - (CH 2}} ) nCN, - (CH 2) nCONR 13 R 14, - (CH 2) nNR 13 R 14, - (CH 2) nOZ, - (CH 2) nW, or, ^{X 1} and Y ¹ are combined to form one another, represents - _{(CO) 2} O or _(-CO) 2 ^{NR 15.}
Here, R ^{11 to} R ¹⁵ each independently represent a hydrogen atom or a hydrocarbon group having 1 to 20 carbon atoms, Z represents a hydrocarbon group or a hydrocarbon group substituted with a halogen, and W represents Si ( R ¹⁶ ) _p D _(3-p) (R ¹⁶ represents a hydrocarbon group having 1 to 10 carbon atoms, D is a halogen atom, —OCOR ¹⁷ or —OR ¹⁷ (R ¹⁷ is a hydrocarbon having 1 to 10 carbon atoms) Group), p is an integer of 0-3. n represents an integer of 0 to 10.
In general formula (AI), R ¹ , R ² , X ¹ and Y ¹ are more preferably each a hydrogen atom.

Addition (co) polymers of norbornene compounds are described in JP-A No. 10-7732, JP-T-2002-504184, U.S. Published Patent Publication No. 200429157157A1, or International Publication No. 2004/070463.
The norbornene compound polymer is obtained by addition polymerization of norbornene compounds (for example, norbornene polycyclic unsaturated compounds).

In addition, as a polymer of norbornene compound, a norbornene compound and an olefin such as ethylene, propylene and butene, conjugated dienes such as butadiene and isoprene, nonconjugated dienes such as ethylidene norbornene, acrylonitrile, acrylic acid, Examples thereof include copolymers obtained by addition copolymerization with an ethylenically unsaturated compound such as acrylic acid, maleic anhydride, acrylic acid ester, methacrylic acid ester, maleimide, vinyl acetate or vinyl chloride. Among these, a copolymer with ethylene is preferable.
Such norbornene compound addition (co) polymers are sold under the trade name of Apel by Mitsui Chemicals, and have different glass transition temperatures (Tg), such as APL8008T (Tg70 ° C.), APL6013T (Tg125). ° C) or APL6015T (Tg145 ° C). In addition, pellets such as TOPAS 8007, 6013, and 6015 are commercially available from Polyplastics. Furthermore, Appear 3000 is commercially available from Ferrania.

  A commercially available product can be used as the polymer of the norbornene compound. For example, it is commercially available from JSR under the trade name Arton G or Arton F, and from Zeon Japan under the trade names Zeonor ZF14, ZF16, Zeonex 250 or Zeonex 280. Yes.

  A hydride of a polymer of a norbornene compound can be synthesized by subjecting a norbornene compound or the like to addition polymerization or metathesis ring-opening polymerization, and then hydrogenating it. Examples of the synthesis method include JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19801, JP-A-2003-1159767, or JP-A-2004-309799. It is described in each gazette.

The mass average molecular weight of the cycloolefin polymer is not particularly limited, but is preferably 10,000 to 1,000,000, more preferably 20,000 to 800,000, still more preferably 30,000 to 500,000, and 50,000 to 300,000. Is particularly preferred, with 50,000 to 200,000 being most preferred. When the molecular weight of the cycloolefin polymer is increased, the heat resistance and mechanical strength are improved. The molecular weight of the cycloolefin polymer can be measured under the following conditions.
As the mass average molecular weight, a mass average molecular weight measured in terms of polystyrene by Gel Permeation Chromatography (GPC) was adopted. Specific measurement conditions are shown below.
-Measurement conditions-
GPC device: GPC device manufactured by Tosoh Corporation (HLC-8320GPC, Ecosec)
Column: TSK gel SuperHZM-H, TSK gel SuperHZ4000, TSK gel SuperHZ2000 combined use (made by Tosoh, 4.6 mm ID (inner diameter) x 15.0 cm)
Eluent: Tetrahydrofuran (THF)
Measurement temperature: 25 ° C
Carrier flow rate: 0.35 mL / min
Sample concentration: 0.1% by mass
Detector: RI (refractive index) detector

4). Method for Laminating Polarizer and Polarizing Plate Protective Film In the method for producing a polarizing plate of the present invention, at least one polarizing plate protective film of the present invention is laminated on at least one surface of the polarizer.
In the method for producing a polarizing plate of the present invention, a polarizing plate protective film surface is treated with an alkali, and a PVA film is immersed and stretched in an iodine solution. It is preferable to produce by the method of bonding using aqueous alcohol solution.

Although it does not specifically limit as an adhesive agent used for bonding the process surface of a polarizing plate protective film, and a polarizer, For example, the aqueous solution of polyvinyl alcohol or polyvinyl acetal (for example, polyvinyl butyral), vinyl polymer (for example, , Polybutyl acrylate) latex, ultraviolet curable adhesive, and the like. Particularly preferred adhesives are aqueous solutions of fully saponified polyvinyl alcohol or UV curable adhesives.
Moreover, the bonding method described in JP-A-2015-11094 and the like can also be preferably used as a method by bonding the polarizing plate protective film of the present invention and a polarizer. That is, after the corona treatment is applied to the surface of the polarizing plate protective film, the active energy ray-curable adhesive composition is applied, bonded to a polarizer, irradiated with ultraviolet rays, and cured after drying the resin. .

  The polarizing plate protective film of the present invention is preferably bonded to the cellulose ester film so that the iodine diffusion preventing layer is closer to the polarizer (see FIGS. 5 and 6). The above configuration is preferable because diffusion of iodine to the polarizing plate protective film can be effectively suppressed, and polarization performance deterioration is less likely to occur when stored in a high temperature and high humidity environment for a long period of time.

The cellulose ester film of the present invention is preferably bonded to the polarizer so that the transmission axis of the polarizer and the slow axis of the cellulose ester film of the present invention are parallel, orthogonal or 45 °. The slow axis can be measured by various known methods, for example, using a birefringence meter (KOBRADH, manufactured by Oji Scientific Instruments).
Here, parallel, orthogonal, or 45 ° includes a range of errors allowed in the technical field to which the present invention belongs. For example, it means that it is within a range of ± 10 ° from a strict angle with respect to parallel, orthogonal and 45 °, respectively, and the error from the strict angle is preferably within a range of ± 5 °, and within a range of ± 3 °. Is more preferable.
The parallel of the transmission axis of the polarizer and the slow axis of the cellulose ester film of the present invention is an angle of ± 10 ° between the direction of the main refractive index nx of the cellulose ester film of the present invention and the direction of the transmission axis of the polarizer. It means that we are in a circle. This angle is preferably within a range of ± 5 °, more preferably within a range of ± 3 °, further preferably within a range of ± 1 °, and most preferably within a range of ± 0.5 °.
Further, the orthogonality of the transmission axis of the polarizer and the slow axis of the cellulose ester film of the present invention means that the direction of the main refractive index nx of the cellulose ester film of the present invention and the direction of the transmission axis of the polarizer are 90 ° ± It means that they intersect at an angle in the range of 10 °. This angle is preferably in the range of 90 ° ± 5 °, more preferably in the range of 90 ° ± 3 °, even more preferably in the range of 90 ° ± 1 °, most preferably 90 ° ± 0.1 °. Within range. If it is the above ranges, the fall of the polarization degree performance under polarizing plate cross Nicol will be suppressed, and light omission will be reduced and it is preferable.

In the present invention, as a method for bonding the polarizing plate protective film and the polarizer, a method of providing an easy-adhesion layer on the surface of the polarizing plate protective film on the side to be bonded to the polarizer is also one preferred embodiment.
Hereinafter, the easy-adhesion layer provided on the surface of the polarizing plate protective film of the present invention that is bonded to the polarizer is referred to as “polarizer-side easy-adhesion layer”.

The polarizer-side easy-adhesion layer is a layer for improving the adhesion between various polarizers and the polarizing plate protective film of the present invention, and is used for bonding the polarizer and the polarizing plate protective film of the present invention. It can be used to improve adhesion with various adhesives. From the viewpoint of improving the polarizer durability, the polarizer-side easy-adhesion layer is preferably provided on the iodine diffusion preventing layer side, and most preferably provided adjacent to the iodine diffusion preventing layer.
From the viewpoint of more effectively increasing the antistatic property of the polarizing plate protective film of the present invention, the polarizer-side easy-adhesion layer preferably contains an organic conductive material, as disclosed in JP-A-2015-102636. Reference can be made to the description of paragraphs [0058] to [0068], the contents of which are incorporated herein. The organic conductive material may be contained only in the polarizer-side easy adhesion layer.

The polarizer-side easy-adhesion layer preferably contains at least one selected from a cellulose acylate resin, a polyester resin, a polyvinyl alcohol resin, an acrylic resin, and a urethane resin, and particularly contains a cellulose acylate resin and / or a urethane resin. Is preferred. Moreover, the polarizer side easily bonding layer may contain the crosslinking agent. The crosslinking agent is preferably an isocyanate compound, and those described in paragraphs [0070] to [0071] of JP-A-2015-102636 can be used. By using a cross-linking agent, the polarizer-side easy-adhesion layer becomes strong, and therefore, in addition to interlayer adhesion, moisture and heat resistance or scratch resistance may be further improved.
Two or more polarizer-side easy-adhesion layers may be provided on the polarizing plate protective film of the present invention. In addition, two or more kinds of the above-described resins may be used in combination in the same layer, or two or more layers having different compositions may be provided as the polarizer-side easy adhesion layer.

Examples of the cellulose acylate resin used in the polarizer easy-adhesion layer include the cellulose acylate described in the cellulose ester layer, and these can be preferably used.
As the polyester resin, the description in paragraphs [0077] to [0079] of JP-A-2015-102636 can be referred to, and the contents thereof are incorporated in the present specification. As the polyvinyl alcohol resin, the descriptions in paragraphs [0080] to [0081] of JP-A-2015-102636 can be referred to, and the contents thereof are incorporated in the present specification. As the acrylic resin, the description in paragraphs [0083] to [0084] of JP-A-2015-102636 can be referred to, and the contents thereof are incorporated in the present specification. As the urethane resin, the description in paragraphs [0085] to [0093] of JP-A-2015-102636 can be referred to, and the contents thereof are incorporated in the present specification.

  In addition, the polarizer-side easy-adhesion layer may be used in combination with a binder polymer other than the above-described resin in order to improve the application surface shape or transparency of the polarizer-side easy-adhesion layer. As the binder polymer, reference can be made to the descriptions in paragraphs [0095] to [0096] of JP-A No. 2015-102636, the contents of which are incorporated herein.

  Further, the polarizer-side easy-adhesion layer may contain an ultraviolet absorber or particles for adjusting the refractive index. As other materials that the polarizer-side easy-adhesion layer may contain, reference can be made to the descriptions in paragraphs [0073] to [0074] of JP-A-2015-102636, the contents of which are incorporated herein. .

  The method of providing the polarizer-side easy-adhesion layer on the polarizing plate protective film of the present invention is not particularly limited. For example, the descriptions in paragraphs [0106] to [0110] of JP-A-2015-102636 can be referred to, and these The contents are incorporated herein.

5. Functionalization of polarizing plate The polarizing plate of the present invention is an antireflection film, a hard coat layer, a brightness enhancement film, a forward scattering layer, or a forward scattering layer for improving the visibility of a liquid crystal display device within the scope of the present invention. It is also preferably used as a functionalized polarizing plate combined with a polarizing plate protective film having a functional layer such as an antiglare (antiglare) layer. The antireflection film, the brightness enhancement film, the other functional optical film, the forward scattering layer, and the antiglare layer for functionalization are described in paragraph numbers 0257 to 0276 of Japanese Patent Application Laid-Open No. 2007-86748. A functionalized polarizing plate can be produced. For details of these, reference can be made to paragraphs 0229 to 0242 and paragraphs 0249 to 0242 and paragraphs 0086 to 0103 of JP2012-215812A, which are disclosed in JP2012-082235A, the contents of which are described in this specification. Incorporated into.

The hard coat layer as the functional layer will be described below.
The cellulose ester film may be provided with a hard coat layer as desired on the surface where the iodine diffusion preventing layer is not provided. For example, a hard-coat layer can be formed on a cellulose-ester film by apply | coating a coating composition on a cellulose-ester film, and making it harden | cure. By adding fillers and additives to the hard coat layer, it is possible to impart mechanical, electrical, optical physical performance, or chemical performance such as water repellency or oil repellency to the hard coat layer. . The thickness of the hard coat layer is preferably in the range of 0.1 to 6 μm, and more preferably in the range of 3 to 6 μm. By having a thin hard coat layer in such a range, it is possible to obtain a polarizing plate including a hard coat layer that has improved physical properties such as brittleness or curl suppression, reduced weight, and reduced manufacturing costs.

  An example of the coating composition for forming the hard coat layer contains a monomer or oligomer for matrix-forming binder, polymers, and an organic solvent. A hard coat layer can be formed by curing the coating composition after coating. For curing, a crosslinking reaction or a polymerization reaction can be used. Details of these can be referred to the descriptions in paragraphs [0088] to [0101] of JP2012-215812A, the contents of which are incorporated herein.

  The coating composition can be prepared, for example, by dissolving and / or dispersing the above-described components in an organic solvent. A coating composition suitable for forming the hard coat layer is a curable composition containing a (meth) acrylate compound. The (meth) acrylate compound includes an acrylic compound and a methacrylic compound.

6). Performance or physical properties of polarizing plate <6-1: Degree of polarization>
In the polarizing plate of the present invention, the degree of polarization is preferably 95.0% or more, more preferably 98% or more, and most preferably 99.5% or more.

  In the present invention, the polarization degree of the polarizing plate can be determined by the following formula (I) from the orthogonal transmittance and the parallel transmittance measured at a wavelength of 380 to 780 nm using an automatic polarizing film measuring device: VAP-7070 (manufactured by JASCO Corporation). ), And the weighted average of the light source (auxiliary illuminant C) and CIE visibility (Y) is calculated according to the following formula (II).

ここで、Ｔ_γ（λ）は偏光度スペクトルを示し、Ｌ（λ）は光源の発光スペクトルを示し、ｙ（λ）は視感度を示す。 Formula (I):
Polarization degree spectrum (%)
= {(Parallel transmittance−Orthogonal transmittance) / (Parallel transmittance + Orthogonal transmittance)} ^1/2 × 100

Here, T _γ (λ) indicates the polarization degree spectrum, L (λ) indicates the emission spectrum of the light source, and y (λ) indicates the visibility.

<6-2: Polarization degree change amount>
The polarizing plate of the present invention is excellent in durability under wet heat aging conditions. For this reason, the amount of change in the degree of polarization before and after the polarizing plate durability test described later is small.
The polarizing plate of the present invention uses an automatic polarizing film measuring device: VAP-7070 (manufactured by JASCO Corporation) to measure orthogonal transmittance and parallel transmittance, and calculate the degree of polarization according to the above formula. It is preferable that the amount of change in polarization degree is less than 5% when stored for 500 hours in an environment with a relative humidity of 85%.

The orthogonal transmittance and the parallel transmittance are respectively measured as follows in a form in which the polarizing plate of the present invention is attached to glass via an adhesive.
Two samples (about 5 cm × 5 cm) in which the polarizing plate of the present invention is pasted on a glass plate so that the polarizing plate protective film side of the present invention is on the air interface side (the side opposite to the glass plate) are prepared. . About these samples, a glass plate side is set toward a light source, and orthogonal transmittance and parallel transmittance are measured. Each of the two samples is measured, and the arithmetic average value is taken as the orthogonal transmittance and the parallel transmittance.

<6-3: Processing characteristics>
The polarizing plate of the present invention preferably has excellent punching characteristics as processing characteristics, such that the cut polarizing plate is less likely to be peeled off or cracked at the end portion even by cutting such as punching.
The polarizing plate is usually cut by punching or the like according to the panel size of the image display device. At this time, if the punching characteristic of the polarizing plate protective film is poor, the yield is reduced and the manufacturing cost is increased. However, the polarizing plate of the present invention includes the above-described polarizing plate protective film, and is excellent in punching workability, thereby avoiding the above-described problems.

<6-4: Surface smoothness>
The polarizing plate protective film of the present invention preferably has high surface smoothness before being bonded to the polarizer. That is, the height difference between adjacent portions in the 500 μm × 500 μm region on the surface to be bonded to the polarizer is less than 0.1 μm.
The surface smoothness can be evaluated by the method described in the examples.
In the polarizing plate of the present invention, when the surface smoothness is high, defects due to foreign matters and the like can be easily detected after manufacturing the polarizing plate protective film, and the quality of the polarizing plate and thus the liquid crystal display device can be improved.

<6-5: Other characteristics>
Other preferable optical characteristics and the like of the polarizing plate of the present invention are described in paragraph numbers 0238 to 0255 of JP-A-2007-086748, and it is preferable to satisfy these characteristics.

[3. Image display device]
The polarizer of the present invention is preferably used as an image display device application using a polarizer.
Examples of such an image display device include a liquid crystal display device and an organic electroluminescence display device.

1. Liquid crystal display device A liquid crystal display device according to an embodiment of the present invention as an image display device includes a liquid crystal cell having a liquid crystal supported between two electrode substrates, and two polarizing plates disposed on both sides thereof. And at least one optical compensation film between the liquid crystal cell and the polarizing plate as necessary.
A preferred embodiment of the liquid crystal display device will be described.

FIG. 7 is a schematic view showing an embodiment of the liquid crystal display device. 7, the liquid crystal display device 20 includes a liquid crystal layer 24 and a first (upper liquid crystal cell) electrode substrate 23 and a second (lower liquid crystal cell) electrode substrate 25 disposed on both surface sides (referred to as upper and lower sides in FIG. 7). A first (upper) polarizing plate 21 and a second (lower) polarizing plate 26 disposed on both sides of the liquid crystal cell. A color filter may be disposed between the liquid crystal cell and each polarizing plate. When the liquid crystal display device 20 is used as a transmission type, a cold cathode or hot cathode fluorescent tube, or a backlight using a light emitting diode, a field emission element, or an electroluminescent element as a light source is provided on the back surface (lower side in FIG. 7). Deploy. The substrate of the liquid crystal cell generally has a thickness of 50 μm to 2 mm.
Although the first polarizing plate 21 and the second polarizing plate 26 are not shown in FIG. 7, the first polarizing plate 21 and the second polarizing plate 26 usually have a configuration in which a polarizer is sandwiched between two polarizing plate protective films. In the liquid crystal display device 20 of the present invention, it is preferable that at least one polarizing plate is the polarizing plate of the present invention. Moreover, after arrange | positioning the polarizing plate protective film of this invention as a polarizing plate protective film of the 1st polarizing plate 21 (viewing side polarizing plate) among two polarizing plates, it is further the 2nd polarizing plate 26 (backlight side). It is also preferable to dispose the polarizing plate protective film of the present invention as the polarizing plate protective film of the polarizing plate). Thereby, expansion / contraction of the polarizer contained in two polarizing plates can be suppressed, and the curvature of a panel can be prevented. The liquid crystal display device 20 of the present invention may be laminated in the order of the polarizing plate protective film of the present invention as a polarizing plate protective film, a polarizer, and a general transparent protective film from the outside of the device (the side far from the liquid crystal cell). preferable.

  The liquid crystal layer 24 of the liquid crystal cell is usually formed by sealing liquid crystal in a space formed by sandwiching a spacer between two substrates. The transparent electrode layer is formed on the substrate as a transparent film containing a conductive substance. Thereby, it becomes an electrode substrate provided with the substrate and the transparent electrode layer. The liquid crystal cell may further be provided with a gas barrier layer, a hard coat layer, or an undercoat layer (undercoat layer) (used for adhesion of the transparent electrode layer). These layers are usually provided on the substrate.

  The polarizing plate protective film of the present invention can also be preferably used as an optical compensation film for liquid crystal display devices. In this case, the liquid crystal display device has a liquid crystal cell in which liquid crystal is supported between two electrode substrates, two polarizers disposed on both sides thereof, and at least between the liquid crystal cell and the polarizer described above. More preferably, the polarizing plate protective film of the present invention is arranged as an optical compensation film.

2. Kind of liquid crystal display device The polarizing plate protective film of the present invention can be used for liquid crystal cells (liquid crystal display devices) of various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroelectric Liquid Crystal), OCB (Optically QuantBandS). Various display modes such as (Electrically Controlled Birefringence) or HAN (Hybrid Aligned Nematic) have been proposed. In addition, a display mode in which the above display mode is oriented and divided has been proposed. The polarizing plate protective film or polarizing plate of the present invention can be suitably used in any display mode liquid crystal display device. Further, it can be suitably used in any of a transmissive type, a reflective type, and a transflective liquid crystal display device.

  The features of the present invention will be described more specifically with reference to examples and comparative 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. Accordingly, the present invention should not be construed as being limited to the specific examples shown below.

[1. Reference Example 101: Preparation of cellulose acylate film]
1. Synthesis of cellulose acetate Cellulose acetate having an acetyl substitution degree of 2.87 and a polymerization degree of 370 was synthesized as follows. The fd _{cellulose of} this cellulose acetate is shown in Table 1.
To the cellulose, sulfuric acid (7.8 parts by mass with respect to 100 parts by mass of cellulose) was added as a catalyst, and acetic acid as a raw material for the acyl substituent was added to carry out an acylation reaction at 40 ° C. After acylation, aging was performed at 40 ° C. Further, the low molecular weight component of the cellulose acetate was removed by washing with acetone. In this way, the above cellulose acetate was synthesized.

2. Preparation of dope 101 for air side surface layer 1.3 parts by mass of the following matting agent solution 2 and 98.7 parts by mass of the following cellulose acylate solution 1 are mixed using an in-line mixer, and the dope 101 solution for the air side surface layer is prepared. Prepared.

<2-1: Preparation of cellulose acylate solution 1>
Each component was put into a mixing tank with the composition shown below and dissolved by stirring to prepare a cellulose acylate solution 1.
―――――――――――――――――――――――――――――――――――
Composition of Cellulose Acylate Solution 1 ――――――――――――――――――――――――――――――――――――
Cellulose acetate with an acetyl substitution degree of 2.87 and a polymerization degree of 370
100.0 parts by mass Sucrose benzoate (benzoyl substitution degree 5.5)
6.0 parts by mass Sucrose acetate isobutyrate manufactured by Sigma-Aldrich
4.0 parts by weight Methylene chloride (first solvent) 353.9 parts by weight Methanol (second solvent) 89.6 parts by weight n-butanol (third solvent) 4.5 parts by weight ――――――――― ――――――――――――――――――――――――――

<2-2: Preparation of matting agent solution 2>
Each component was put into a disperser with the composition shown below and dissolved by stirring to prepare a matting agent solution 2.
―――――――――――――――――――――――――――――――――――
Composition of Matte Solution 2 ―――――――――――――――――――――――――――――――――――
Silica particles having an average particle size of 20 nm (AEROSIL R972,
2.0 parts by mass Methylene chloride (first solvent) 69.3 parts by mass Methanol (second solvent) 17.5 parts by mass n-butanol (third solvent) 0.9 parts by mass The cellulose acylate Solution 1 0.9 parts by mass ―――――――――――――――――――――――――――――――――――

3. Preparation of Base Layer Dope 102 (Cellulose Acylate Solution 3) Each component was charged into a mixing tank with the composition shown below, and dissolved by stirring to prepare a base layer dope 102.

―――――――――――――――――――――――――――――――――――
Composition of base layer dope 102 ―――――――――――――――――――――――――――――――――――
Cellulose acetate with an acetyl substitution degree of 2.87 and a polymerization degree of 370
100.0 parts by mass Sucrose benzoate (benzoyl substitution degree 5.5)
6.0 parts by mass Sucrose acetate isobutyrate manufactured by Sigma-Aldrich
4.0 parts by mass The following UV absorber C 2.0 parts by mass Methylene chloride (first solvent) 297.7 parts by mass Methanol (second solvent) 75.4 parts by mass n-butanol (third solvent) 3.8 parts by mass Department ――――――――――――――――――――――――――――――――――――

4). Preparation of support-side surface layer dope 103 solution 1.3 parts by mass of matting agent solution 2 and 99.3 parts by mass of cellulose acylate solution 1 prepared in air layer-side surface dope 101 solution were prepared using an in-line mixer. And mixed to prepare a support 103 side surface dope 103 solution.

5. Film Formation of Film FIG. 8 is a diagram for explaining a method for producing a cellulose acylate film having a three-layer structure using a drum casting apparatus. In FIG. 8, 89 is a casting die, and 70 is a casting film cast with a dope.
Using the drum casting apparatus shown in FIG. 8, 122 in FIG. 8 is a support-side surface dope 103, 120 is a base layer dope 102, 121 is an air-side surface dope 101, and three layers are made of stainless steel simultaneously. It casted uniformly from the casting port provided in the casting die 89 to the cast casting support body 85 (support body temperature -9 degreeC). Stripped in a state where the amount of residual solvent in the dope of each layer is about 70% by mass, fixed both ends in the width direction of the film with a pin tenter, and 1.28 in the lateral direction in a state of residual solvent amount of 3-5% by mass. The film was dried while being stretched twice. Thereafter, the film was further dried by being conveyed between rolls of a heat treatment apparatus. 101 was obtained. The obtained cellulose acylate film No. The thickness of 101 was 60 μm (air side surface layer (121a in FIG. 8) 3 μm, the base layer (120a in FIG. 8) 54 μm, the support side surface layer (122a in FIG. 8) 3 μm), and the width was 1480 mm.

[2. Examples 101-107 and Comparative Examples 201-208]
In Examples 101 to 107 and Comparative Examples 203 to 208, a polarizing plate protective film (FIG. 1) directly provided with an iodine diffusion preventing layer on one surface of a polarizer, and a polarizing plate (FIG. 6) provided with the same. ) And the characteristics thereof were evaluated.
For Comparative Examples 201 and 202, only the cellulose acylate film was used as the polarizing plate protective film.

1. Example 101
<1-1: Production of polarizing plate protective film>
A polarizing plate protective film 10A provided with the iodine diffusion prevention layer (polymer B1 layer) 12 having a single layer structure shown in FIG. 1 was produced as follows.
(Preparation of Composition Ba-1 for Formation of Iodine Diffusion Prevention Layer)
Each component was mixed with the composition shown below, and filtered with a polypropylene filter having a pore size of 30 μm to prepare an iodine diffusion preventing layer forming composition Ba-1.
In preparing the composition Ba-1, the cellulose acylate film No. used as a solvent was used. 101, the fd value of the cellulose acylate contained in 101 and the fd value of the following polymer B1 (polymethyl methacrylate: PMMA) are respectively the above-mentioned relational expression [1] and relational expression [2]. Filling propyl acetate was selected.
In this _{case, it fd Solvent} and _{fd PolymerB1,} as well, equation _{[1] (| fd solvent -fd} cellulose |) and equation _{[2] (| fd solvent -fd} polymerB1 |) the calculated values of, shown in Table 1 It was.

―――――――――――――――――――――――――――――――――――
Composition of Composition Ba-1 for Formation of Iodine Diffusion Prevention Layer ―――――――――――――――――――――――――――――――――――
Polymethylmethacrylate: Mitsubishi Rayon Dianal BR83
18.0 parts by mass Propyl acetate (solvent) 82.0 parts by mass ―――――――――――――――――――――――――――――――――――
Mitsubishi Rayon's Dianal BR83 had a glass transition temperature of 116 ° C. according to the above measurement method, and a weight average molecular weight of 40000. This weight average molecular weight was measured by gel permeation chromatography (Gel Permeation Chromatography; GPC) in terms of polystyrene. Specific measurement conditions are shown below.
-Measurement conditions-
GPC device: GPC device manufactured by Tosoh Corporation (HLC-8320GPC, Ecosec)
Column: TSK gel SuperHZM-H, TSK gel SuperHZ4000, TSK gel SuperHZ2000 combined use (made by Tosoh, 4.6 mm ID (inner diameter) x 15.0 cm)
Eluent: Tetrahydrofuran Measurement temperature: 25 ° C
Carrier flow rate: 0.35 mL / min
Sample concentration: 0.1% by mass
Detector: RI (refractive index) detector

(Formation of iodine diffusion preventing layer (polymer B1 layer) 12)
When the film described in Reference Example 101 was formed, the cellulose acylate film No. On the surface of 101 (the surface of the support-side surface layer 122a), the iodine diffusion preventing layer coating liquid Ba-1 was applied by a microgravure coating method under the condition of a conveyance speed of 30 m / min. This was dried at 100 ° C. for 120 seconds to form an iodine diffusion preventing layer 12 having a thickness of 5 μm.
The polarizing plate protective film 10A provided with the iodine diffusion preventing layer 12 thus obtained was applied to the polarizing plate protective film No. 10 of Example 101. 101.

<1-2: Preparation of polarizing plate>
In the following manner, the polarizing plate protective film No. The polarizing plate (FIG. 6) provided with 101 and the cycloolefin type | system | group film was produced.
(Preparation of active energy ray-curable adhesive composition)
Each component was mixed by the composition shown below, and it stirred at 50 degreeC for 1 hour, and obtained the active energy ray hardening-type adhesive composition.
―――――――――――――――――――――――――――――――――――
Composition of active energy ray-curable adhesive composition ―――――――――――――――――――――――――――――――――――
Radical polysynthetic compound: Aronix M-220 manufactured by Toa Gosei Co., Ltd.
20.0 parts by mass N-hydroxylacrylamide manufactured by Kojin Co., Ltd.
40.0 parts by mass Acroyl morpholine manufactured by Kojin Co., Ltd. 40.0 parts by mass radical polymerization initiator: KAYACURE DETX-S manufactured by Nippon Kayaku Co., Ltd.
0.5 parts by mass Radical polymerization initiator: IRGACURE907 manufactured by BASF
1.5 parts by mass ――――――――――――――――――――――――――――――――――――

(Production of polarizer)
A polyvinyl alcohol film having an average polymerization degree of 2400, a saponification degree of 99.9 mol%, and a thickness of 75 μm was immersed in warm water at 30 ° C. for 60 seconds to swell. Next, the film was stretched to 3.5 times while being dyed in an iodine solution of 0.3% by mass (mass ratio: iodine / potassium iodide = 0.5 / 8) at 30 ° C. for 1 minute. Thereafter, the film was stretched until it was 6 times in total stretch ratio while being immersed in a 4% by mass boric acid aqueous solution at 65 ° C. for 0.5 minutes. After stretching, drying was performed in an oven at 70 ° C. for 3 minutes to obtain a polarizer having a thickness of 26 μm. The moisture content of the polarizer was 13.5% by mass.

(Lamination)
The produced polarizing plate protective film No. The surface of 101 on the iodine diffusion preventing layer side was subjected to corona treatment. The active energy ray-curable adhesive composition prepared above is applied to the surface of the iodine diffusion preventing layer subjected to corona treatment (MCD coater (manufactured by Fuji Machine)) (cell shape: honeycomb, number of gravure roll wires: 1000 / (INCH, rotational speed 140% / vs line speed) was applied to a thickness of 0.5 μm.
Separately, a 40 μm thick cycloolefin film (Arton G7810 manufactured by JSR) was subjected to corona treatment, and the surface was similarly coated with the active energy ray-curable adhesive composition having a thickness of 0. It was applied so as to be 5 μm.
This cycloolefin-based film is derived from a norbornene compound represented by the above general formula A-II (where m = 1, R ³ , R ⁴ , X ² and Y ² are all hydrogen atoms) as a repeating unit. And a structural unit represented by the following general formula (AI) (wherein R ¹ , R ² , X ¹ and Y ¹ are all hydrogen atoms).

Thus, polarizing plate protective film No. which apply | coated each active energy ray hardening-type adhesive composition was used. 101 and a cycloolefin-based film were produced.
Then, the surface which apply | coated the active energy ray hardening-type adhesive composition of each film was bonded together to the one side surface of a polarizer, respectively. At this time, the transmission axis of the polarizer and the polarizing plate protective film No. Arrangement was made so that the slow axis of 101 was vertical. Then, it heated at 50 degreeC using IR heater from both surfaces of the bonded film (polarizing plate protective film No. 101 or a cycloolefin type film).
Furthermore, the active energy rays shown below were irradiated from both surfaces of the bonded film (polarizing plate protective film No. 101 or cycloolefin film) to cure the active energy ray-curable adhesive composition, respectively. .
Thereafter, it was dried with hot air at 70 ° C. for 3 minutes. 101 was obtained.

− Active energy line −
As active energy rays, ultraviolet rays (gallium filled metal halide lamp), irradiation apparatus: Fusion UV Systems, Inc. Light HAMMER10, bulb: V bulb, peak illuminance: 1600 mW / cm ² , integrated irradiation amount 1000 / mJ / cm ² (wavelength) 380-440 nm) was used. In addition, the illumination intensity of the ultraviolet-ray was measured using the Sola-Check system by Solatell.

2. Example 102
<2-1: Polarizing plate protective film No. 102 and polarizing plate No. Production of 102>
In the preparation of the composition for forming an iodine diffusion preventing layer Ba-1 in Example 101, the polymer B1 (polymethyl methacrylate) in the iodine diffusion preventing layer was changed to the polymer A having the following structure, and propyl acetate was used. In the same manner as in Example 101 except that methyl ethyl ketone (MEK) was changed as a solvent satisfying the above relational expressions, the polarizing plate protective film No. 102 and polarizing plate No. 102 was produced.
In changing the polymer and the solvent, etc., the fd value of the cellulose acylate, the fd value of the polymer A, and the fd value of the solvent were selected so as to satisfy the relational expression [1] and the relational expression [2]. .

ａ／ｂ＝５０／５０（モル比率）

a / b = 50/50 (molar ratio)

<2-2: Synthesis of polymer A>
In a 300 mL Erlenmeyer flask, 47.8 g (0.47 mol) of methyl methacrylate, 102.2 g (0.47 mol) of 2-acetoacetoxyethyl methacrylate, 0.93 g (0.004 mol) of dimethyl 2,2′-azobisisobutyrate Then, 75.0 g of methyl ethyl ketone was weighed and mixed and dissolved to prepare a monomer composition.
In a 1 L three-necked flask equipped with a thermometer, stirring blades, and reflux ring, 75.0 g of methyl ethyl ketone was charged and stirred at 85 ° C. under a nitrogen stream. The monomer composition was dropped into the methyl ethyl ketone at a rate of 1.2 mL / min. A chemical pump was used for dripping. This was further stirred at 85 ° C. for 6 hours, and then the resulting reaction solution was allowed to cool to room temperature (25 ° C.), diluted with 500 mL of methyl ethyl ketone, and added to 5 L of methanol to obtain a white precipitate. The obtained white precipitate was filtered off, then redispersed and washed with 2 L of methanol three times, and dried at 60 ° C. overnight to obtain 139.6 g of the target polymer A. The composition ratio of the obtained polymer A was a / b = 50/50 (molar ratio), and the weight average molecular weight was 74,000.

<2-3: Evaluation of polymer>
The structure and composition ratio of the repeating unit were identified by ¹ H-NMR measurement using a BRUKER nuclear magnetic resonance spectrum measuring apparatus (NMR 300 MHz).
As the weight average molecular weight, a weight average molecular weight measured in terms of polystyrene by gel permeation chromatography (GPC) was adopted. Specific measurement conditions are the same as those of the above-mentioned Dianar BR83.

3. Example 103
<3-1: Production of cellulose acylate film>
In Reference Example 101, Reference Example 103 was performed in the same manner as Reference Example 101, except that the cellulose acylate solution 1 used for the air side surface dope and the support side surface layer dope was changed to the cellulose acylate solution 5 having the following composition. Cellulose acylate film no. 103 was produced.
The fd _{cellulose of} the cellulose acetate used is shown in Table 1.

(Preparation of cellulose acylate solution 5)
Each component was put into a mixing tank with the composition shown below and dissolved by stirring to prepare a cellulose acylate solution 5.
――――――――――――――――――――――――――――――――――――
Composition of Cellulose Acylate Solution 5 ――――――――――――――――――――――――――――――――――――
Cellulose acetate with an acetyl substitution degree of 2.87 and a polymerization degree of 370
100.0 parts by mass Sucrose benzoate (benzoyl substitution degree 5.5)
6.0 parts by mass Sucrose acetate isobutyrate manufactured by Sigma-Aldrich
4.0 parts by mass Polymer A 15.0 parts by mass Methylene chloride (first solvent) 353.9 parts by mass Methanol (second solvent) 89.6 parts by mass n-butanol (third solvent) 4.5 parts by mass ―――――――――――――――――――――――――――――――――――

<3-2: Production of polarizing plate protective film and polarizing plate>
In Example 101, instead of propyl acetate, methyl ethyl ketone (MEK) was used as the solvent satisfying the above relational expressions, and cellulose acylate film No. 1 was used. In place of 101, the cellulose acylate film no. The polarizing plate protective film No. of Example 103 was the same as Example 101 except that 103 was used. 103 and polarizing plate No. 103 was produced.
In changing the solvent, etc., the fd value of cellulose acylate, the fd value of polymer B1 (polymethyl methacrylate: PMMA), and the fd value of the solvent satisfy the relational expressions [1] and [2]. So selected.

4). Examples 104 and 105
In the preparation of the iodine diffusion preventing layer forming composition Ba-1 of Example 101 above, Example 101 was used except that instead of propyl acetate, the solvent described in Table 1 was used as the solvent satisfying the above relational expressions. In the same manner as in Examples 104 and 105, the polarizing plate protective film No. 104 and 105 and polarizing plate No. 104 and 105 were produced.

5. Example 106
In the production of the polarizing plate of Example 101, the surface of the cellulose acylate film was subjected to corona treatment, and then the active energy ray-curable adhesive composition was applied to the surface opposite to the iodine diffusion preventing layer 12 to diffuse the iodines. The polarizing plate No. 10 of Example 106 was the same as Example 101 except that the prevention layer 12 was bonded to the cellulose acylate layer so as to be opposite to the polarizer. 106 was produced.

6). Example 107
On the iodine diffusion prevention layer (polymer B1 layer) 12 containing the polymer A prepared in Example 102, the iodine diffusion prevention layer forming composition Ba-1 prepared in Example 101 was treated in the same manner as in Example 101. The polarizing plate protective film No. 1 of Example 107 provided with an iodine diffusion preventing layer having a two-layer structure shown in FIG. 107 was produced.
Subsequently, in preparation of the polarizing plate of Example 101, polarizing plate protective film No.1. In place of 101, polarizing plate protective film No. The polarizing plate No. 107 in Example 107 was prepared in the same manner as in the production of the polarizing plate in Example 101 except that 107 was used. 107 was produced.
Polarizing plate No. In 107, the iodine diffusion preventing layer 13 and a polarizer were bonded together.

7). Comparative Example 201
<7-1: Production of cellulose acylate film>
Reference Example 101 is the same as Reference Example 101 except that cellulose acylate solution 1 is changed to cellulose acylate solution 6 having the following composition, and cellulose acylate solution 3 is changed to cellulose acylate solution 7 having the following composition. In the comparative example 201, the cellulose acylate film No. 201 was produced.
The fd _{cellulose of} the cellulose acetate used is shown in Table 1.

(Preparation of cellulose acylate solution 6)
Each component was put into a mixing tank with the composition shown below, and dissolved by stirring to prepare a cellulose acylate solution 6.
―――――――――――――――――――――――――――――――――――
Composition of Cellulose Acylate Solution 6 ――――――――――――――――――――――――――――――――――――
Cellulose acetate with an acetyl substitution degree of 2.87 and a polymerization degree of 370
100.0 parts by mass Sucrose benzoate (benzoyl substitution degree 5.5)
6.0 parts by mass Sucrose acetate isobutyrate manufactured by Sigma-Aldrich
4.0 parts by mass Polymer A 15.0 parts by mass Methylene chloride (first solvent) 353.9 parts by mass Methanol (second solvent) 89.6 parts by mass n-butanol (third solvent) 4.5 parts by mass ――――――――――――――――――――――――――――――――――

(Preparation of cellulose acylate solution 7)
Each component was put into a mixing tank with the composition shown below and dissolved by stirring to prepare a cellulose acylate solution 7.
―――――――――――――――――――――――――――――――――――
Composition of Cellulose Acylate Solution 7 ――――――――――――――――――――――――――――――――――――
Cellulose acetate with an acetyl substitution degree of 2.87 and a polymerization degree of 370
100.0 parts by mass Sucrose benzoate (benzoyl substitution degree 5.5)
6.0 parts by mass Sucrose acetate isobutyrate manufactured by Sigma-Aldrich
4.0 parts by mass Polymer A 15.0 parts by mass The following UV absorber C 2.0 parts by mass Methylene chloride (first solvent) 297.7 parts by mass Methanol (second solvent) 75.4 parts by mass n-butanol ( 3rd solvent) 3.8 parts by mass ―――――――――――――――――――――――――――――――――――

<7-2: Production of polarizing plate protective film>
Cellulose acylate film No. 201 is polarizing plate protective film No. 201.

<7-3: Production of polarizing plate>
(Saponification treatment of polarizing plate protective film)
The produced polarizing plate protective film No. 201 was immersed in a 2.3 mol / L sodium hydroxide aqueous solution at 55 ° C. for 3 minutes. Then, it wash | cleaned in the water bath at room temperature, and neutralized using 0.05 mol / L sulfuric acid at 30 degreeC. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C. In this way, the polarizing plate protective film No. The surface of 201 was saponified.

(Lamination)
The polarizing plate protective film No. 1 of Comparative Example 201 subjected to saponification treatment was used. A drum (support) side surface surface 122a of 201 was attached to one side surface of a polarizer manufactured in the same procedure as in Example 101, using a polyvinyl alcohol-based adhesive. Further, a cycloolefin-based film (Arton G7810 manufactured by JSR Co.) subjected to corona treatment and application of an active energy ray-curable adhesive composition in the same manner as in Example 101 was bonded to the opposite surface of the polarizer. Then, from the laminated cycloolefin film side (one side), it heats to 50 degreeC using IR heater, and irradiates the said ultraviolet-ray to the cycloolefin film side, and an active energy ray hardening-type adhesive composition is carried out. Cured. Thereafter, it was dried with hot air at 70 ° C. for 3 minutes. 201 was obtained.

8). Comparative Example 202
Cellulose acylate film no. 101 is polarizing plate protective film No. 101. 202.
In the production of the polarizing plate of Comparative Example 201, cellulose acylate film No. In place of 201, the cellulose acylate film no. The polarizing plate No. of Comparative Example 202 was the same as Comparative Example 201 except that 101 was used. 202 was produced.

9. Comparative Example 203
In Example 101, a comparative example was made in the same manner as in Example 101 except that the composition Ba-1 for forming an iodine diffusion preventing layer was changed to a composition Ba-5 for forming an iodine diffusion preventing layer having the following composition. No. 203 polarizing plate protective film No. 203 and polarizing plate No. 203 was produced.
Table 1 shows the calculated values of fd _solvent and fd _polymerB1 , and relational expressions [1] and [2] in Comparative Example 203.

――――――――――――――――――――――――――――――――――――
Composition of Composition Ba-5 for Iodine Diffusion Prevention Layer Formation ――――――――――――――――――――――――――――――――――――
Cycloolefin polymer: Mitsui Chemicals TOPAS APL6013T
18.0 parts by mass Cyclohexane (solvent) 82.0 parts by mass ―――――――――――――――――――――――――――――――――――
The repeating unit of TOPAS APL6013T has a structure derived from a norbornene compound represented by the above general formula (A-II) (where m = 0, R ³ , R ⁴ , X ² and Y ² are all hydrogen atoms). A polymer having units.
The weight average molecular weight of this TOPAS APL6013T was 10800. The measurement condition of the weight average molecular weight is the same as that of the above-mentioned Dianar BR83.

10. Comparative Examples 204-208
In the preparation of the iodine diffusion preventing layer forming composition Ba-1 of Example 101, in place of propyl acetate, the solvent described in Table 1 was used as a solvent not satisfying at least one of the above relational expressions. In the same manner as in Example 101, the polarizing plate protective film No. of Comparative Examples 204-208. 204-208 and polarizing plate no. 204-208 were produced.

[3 Evaluation of polarizing plate protective film and polarizing plate]
The polarizing plate protective film obtained above was evaluated for moisture permeability and adhesion, and for the polarizing plate, polarizing plate durability was evaluated by the following method. The results are shown in Table 1.

Moisture permeability The moisture permeability in the polarizing plate protective film of the present invention was calculated by the following method based on “moisture-proof packaging material moisture permeability test method (cup method)” of JIS Z 0208 (1976).
Specifically, the polarizing plate protective film is cut to 60 mm × 60 mm, and the mass of water passing through the cut polarizing plate protective film in an atmosphere of 85 ° C. and 85% relative humidity in 6 hours (g / 6hours) Was measured and converted into a mass per 1 m ^{2 of} the cut polarizing plate protective film (g / m ² / 6ours).
The mass of moisture that passed through the polarizing plate protective film was calculated from the mass change of the moisture absorbent (anhydrous calcium chloride).

2. Adhesiveness First, a polarizing plate protective film provided with an iodine diffusion preventing layer was conditioned to a polarizing plate protective film at a temperature of 25 ° C. and a relative humidity of 60% for 2 hours. On the surface having the iodine diffusion preventing layer, 11 vertical and 11 horizontal cuts were made at a 1 mm interval with a cutter knife, and a total of 100 square squares were carved. A polyester pressure-sensitive adhesive tape (No. 31B) manufactured by Nitto Denko Co., Ltd. was attached to the surface (grid). After 30 minutes, the tape was quickly peeled off in the vertical direction, and the number of squares peeled off was counted and evaluated according to the following four criteria. The same adhesion evaluation was performed 3 times and the average was taken.
In this test, as for adhesion, rank A or B is a pass level.
In addition, since the polarizing plate protective film of the comparative examples 201 and 202 consists only of a cellulose acylate film, the adhesiveness test is not performed. In Table 1, it is indicated by “−”.
(Evaluation criteria)
A: No peeling was observed at 100 mm.
B: Peeling of 1 to 10 mm was observed at 100 mm.
C: Peeling of 11 mm or more was observed at 100 mm.
D: Peeling was recognized at the time of cutting with a cutter knife.

3. Polarizing plate durability About the polarizing plate of each Example and comparative example produced above, the polarization degree was measured by the method mentioned above. Then, after storing for 500 hours in an environment of 85 ° C. and 85% relative humidity, the degree of polarization after storage was measured in the same manner.
The amount of change in polarization degree before and after storage was determined by the following formula, and the obtained amount of change in polarization degree was evaluated according to the following criteria as the durability of the polarizer.

Polarization degree change (%) = | Polarization degree after storage (%) − Polarization degree before storage (%) |

(Evaluation criteria)
A: Polarization degree change amount is less than 0.1% B: Polarization degree change amount is 0.1% or more and less than 1% C: Polarization degree change amount is 1 or more and less than 5% D: Polarization degree change amount is 5% or more

4). Confirmation of mixed region When the vicinity of the boundary between the cellulose acylate layer 11 and the polymer layer 12 was confirmed by the above method, the polarizing plate protective films of Examples 101 to 107 had a mixed region.

From the results in Table 1, the polarizing plate protective film No. 1 of the present invention was obtained. When 101 to 107 are used for polarizing plates, all are polarizing plate protective films No. For 201 and 202, it was shown that a decrease in the degree of polarization can be suppressed even when stored in a high temperature and high humidity environment. Furthermore, the polarizing plate protective film No. 1 of the present invention. 101 to 107 are polarizing plates No. For Comparative Example No. 203, polarizing plate No. For any of 204 to 208, the interlayer adhesion between the iodine diffusion preventing layer and the cellulose acylate layer was excellent.
Further, the iodine diffusion preventing layer was disposed on the side closer to the polarizer with respect to the cellulose acylate film (the iodine diffusion preventing layer was disposed adjacent to the polarizer through the adhesive layer). No. 101 is a polarizing plate No. 101 in which the iodine diffusion preventing layer is disposed on the far side from the polarizer with respect to the cellulose acylate film. Compared to 106, it was found that polarization performance is hardly deteriorated when stored in a high-temperature and high-humidity environment, which is particularly preferable.
Furthermore, polarizing plate protective film No. 1 provided with an iodine diffusion preventing layer containing polymer A containing each of the repeating units [a] and [b] described above on the surface layer of the cellulose acylate film. No. 102 is a polarizing plate protective film No. 102 provided with an iodine diffusion preventing layer containing a polymer that does not contain the repeating unit [b] when used in a polarizing plate. In contrast, the interlaminar adhesion between the cellulose acylate film and the iodine diffusion preventing layer was further improved.

[4. Examples 301-302 and Comparative Example 401]
In Examples 301 and 302, a polarizing plate protective film (FIG. 1) in which an iodine diffusion preventing layer was directly provided on one surface of a polarizer, and a polarizing plate provided with the protective film were prepared, and the characteristics were evaluated. did.
For Comparative Example 401, a polarizing plate protective film in which only the cellulose acylate film was directly provided on both surfaces of the polarizer, and a polarizing plate provided therewith were prepared.

1. Example 301
In Example 301, a polarizing plate protective film No. 1 in which an iodine diffusion preventing layer was directly provided on both surfaces of the polarizer as follows. 301 (FIG. 1) and polarizing plates provided with the same were prepared.
<1-1: Preparation of Cellulose Acylate Film 301A>
(Preparation of core layer dope solution 301A)
Each component was put into a mixing tank with the composition shown below and dissolved by stirring to prepare a core layer dope solution 301A.
――――――――――――――――――――――――――――――――――――
Preparation of core layer dope solution 301A ――――――――――――――――――――――――――――――――――――
Cellulose acetate (acetyl substitution degree 2.43) 100 parts by mass additive 1 (the following oligomer 1) 4 parts by mass additive 2 (the following compound P-5) 7.5 parts by mass methylene chloride 394.0 parts by mass methanol 59 0 parts by mass ――――――――――――――――――――――――――――――――――――

-Oligomer 1-
After reacting the following molar ratios of terephthalic acid and succinic dicarboxylic acid with the following molar ratios of ethylene glycol and propylene glycol diol, the end-capping was performed to obtain oligomer 1. Table 2 shows the types and molar ratios (feed ratios) of the dicarboxylic acid and diol as raw materials, and the end-capping structure and molecular weight of the obtained oligomer 1.

(Preparation of skin layer dope solution)
Each component was put into a mixing tank with the composition shown below and dissolved by stirring to prepare a skin layer dope solution.
The fd value of the cellulose acetate used (acetyl substitution degree 2.81) was 0.389.
――――――――――――――――――――――――――――――――――――
Composition of skin layer dope solution ――――――――――――――――――――――――――――――――――――
Cellulose acetate (acetyl substitution degree 2.81) 100 parts by mass Methylene chloride 425.0 parts by mass Methanol 63.0 parts by mass ――――――――――――――――――――――― ――――――――――――

(Adjustment of matting agent solution)
Each component was charged into a disperser with the composition shown below, and dissolved by stirring to prepare a matting agent dispersion M1.
――――――――――――――――――――――――――――――――――――
Preparation of matting agent dispersion M1 ――――――――――――――――――――――――――――――――――――
2.0 parts by mass of silica particles having an average particle size of 20 nm (AEROSIL (registered trademark) R972, manufactured by Nippon Aerosil Co., Ltd.)
Methylene chloride 76.1 parts by mass Methanol 11.4 parts by mass The skin layer dope solution prepared above 12.6 parts by mass ――――――――――――――――――――――――― ――――――――――――

(Preparation of skin layer dope solution containing matting agent)
The skin layer dope solution prepared above was mixed with the matting agent dispersion M1 at the ratio shown below to prepare a skin layer dope solution containing a matting agent.
――――――――――――――――――――――――――――――――――
Preparation of skin layer dope solution ――――――――――――――――――――――――――――――――――
Skin layer dope solution 100.0 parts by mass Matting agent dispersion M1 7.1 parts by mass ――――――――――――――――――――――――――――――― ―――

(Casting)
The dope solution prepared above was used for casting with a band casting machine.
In FIG. 8, the core layer dope solutions 301A, 122, and 121 are co-cast so that the skin layer dope solution containing the matting agent is used. Here, by adjusting the casting amount of each dope, the core layer is made the thickest. As a result, the film thickness after stretching is 40 μm for the core layer and 2 μm for the skin layer. A cast film was cast.

  Next, this cast film was peeled off from the cast band 85 to form a wet film, and then dried with a transition part and a tenter. In addition, the residual solvent amount of the wet film immediately after peeling off the dope was about 25% by mass. The wet film was sent to a drying chamber, and while being wound around a large number of rollers, drying was sufficiently promoted to obtain a film obtained by casting.

(Stretching)
The film obtained by casting was gripped with a clip and stretched in the transverse direction under the condition of uniaxial fixed end. The stretching temperature was 185 ° C. and the stretching rate was 31%.

(Humid heat treatment)
Each film subjected to the stretching treatment was sequentially subjected to a condensation prevention treatment, a wet heat treatment (water vapor contact treatment) and a heat treatment.
In the anti-condensation treatment, the film temperature Tf0 was adjusted to 120 ° C. by applying dry air to each film.
In the wet heat treatment (water vapor contact treatment), the absolute humidity (humid heat treatment absolute humidity) of the wet gas in the wet gas contact chamber was set to 250 g / m ³ . Further, the dew point of the wet gas was adjusted so as to be higher by 10 ° C. than the temperature Tf0 of each film. Thus, each film was conveyed, maintaining only the processing time (60 second) that the temperature (wet heat treatment temperature) of each film was 100 ° C.
In the heat treatment, the absolute humidity of the gas in the heat treatment chamber (heat treatment absolute humidity) is set to 0 g / m ³ , the temperature of each film (heat treatment temperature) is set to the same temperature as the wet heat treatment temperature, and the treatment time (2 minutes) is maintained. did. The film surface temperature was determined from the average value of three tape-type thermocouple surface temperature sensors (ST series manufactured by Anri Keiki Co., Ltd.) attached to the film.

(Take-up)
Then, after cooling to room temperature, the film was wound up. The thickness of each layer in the cellulose acylate film 301A thus produced was 40 μm for the core layer and 2 μm for the skin layer.

<1-2: Preparation of Composition Ba-2 for Formation of Iodine Diffusion Prevention Layer>
(Preparation of matting agent solution M3)
Each component was charged into a disperser with the composition shown below, and dissolved by stirring to prepare a matting agent solution M3.
――――――――――――――――――――――――――――――――――――
Preparation of matting agent solution M3 ――――――――――――――――――――――――――――――――――――
2.0 parts by mass of silica particles having an average particle size of 20 nm (product name: Aerosil NX90S, manufactured by Nippon Aerosil Co., Ltd.)
Polymethylmethacrylate: Mitsubishi Rayon Dianal BR80
4.0 parts by mass Propyl acetate 94.0 parts by mass ―――――――――――――――――――――――――――――――――――

(Preparation of Composition Ba-2 for Formation of Iodine Diffusion Prevention Layer)
Each component was mixed with the composition shown below, and filtered with a polypropylene filter having a pore diameter of 10 μm to prepare an iodine diffusion preventing layer forming composition Ba-2.
In the preparation of the composition Ba-2, the fd value is related to the fd value of the cellulose acylate contained in the skin layer 122a and the fd value of the following polymer B1 (polymethyl methacrylate) as a solvent. Propyl acetate satisfying the formula [1] and the above relational expression [2] was selected.
Table 3 shows the calculated values of fd _polymerB1 and relational expressions [1] and [2] at this time.

――――――――――――――――――――――――――――――――――――
Composition of iodine diffusion preventing layer forming composition Ba-2 ――――――――――――――――――――――――――――――――――――
Polymethylmethacrylate: Mitsubishi Rayon Dianal BR80
10.0 parts by mass The following fluoropolymer F (weight average molecular weight 14900) 0.05 parts by mass Matting agent solution M3 25.0 parts by mass Propyl acetate (solvent) 65.0 parts by mass ――――――――― ―――――――――――――――――――――――――――

上記フッ素系ポリマーＦの重量平均分子量の測定は、ゲル浸透クロマトグラフィーによりポリスチレン換算で測定した。上記繰り返し単位及びに付した数字は、各繰り返し単位のモル比を表す。

The weight average molecular weight of the fluoropolymer F was measured in terms of polystyrene by gel permeation chromatography. The above-mentioned repeating units and the numbers given to them represent the molar ratio of each repeating unit.

<1-3: Formation of iodine diffusion preventing layer (polymer B1 layer)>
The produced cellulose acetate film No. On the band surface of 301A (the surface of the support side surface layer 122a of the cellulose acylate film that was in contact with the stainless steel casting support at the time of film formation), the coating solution Ba-2 for the iodine diffusion preventing layer prepared as described above. Was applied by a micro gravure coating method under conditions of a conveyance speed of 30 m / min. This was dried at 100 ° C. for 120 seconds to form an iodine diffusion preventing layer 12 having a thickness of 5 μm.
In this manner, the polarizing plate protective film o.e. having the single-layered iodine diffusion preventing layer 12 shown in FIG. 301A was obtained.

<1-4: Preparation of cellulose acylate film 301B>
(Preparation of dope 301B for air side surface layer)
1.3 parts by mass of the following matting agent solution 302B and 98.7 parts by mass of the following cellulose acylate solution 301B were added and mixed using an in-line mixer to prepare an air-side surface dope 301B.

Each component was put into a mixing tank with the composition shown below and dissolved by stirring to prepare a cellulose acylate solution 301B.
――――――――――――――――――――――――――――――――――――
Composition of Cellulose Acylate Solution 301B ――――――――――――――――――――――――――――――――――――
Cellulose acetate with an acetyl substitution degree of 2.87 and a polymerization degree of 370
100.0 parts by mass Sucrose benzoate (benzoyl substitution degree 5.5)
3.0 parts by mass Sucrose acetate isobutyrate manufactured by Sigma-Aldrich
1.0 part by mass The following barbituric acid derivative (E) 6.0 parts by mass The following ultraviolet absorber (D) 2.3 parts by mass Methylene chloride (first solvent) 353.9 parts by mass Methanol (second solvent) 89.6 parts by mass n-butanol (third solvent) 4.5 parts by mass ------------- ――――

Each component was charged into a disperser with the composition shown below, and dissolved by stirring to prepare a matting agent solution 302B.
――――――――――――――――――――――――――――――――――――
Composition of matting agent solution 302B ――――――――――――――――――――――――――――――――――――
Silica particles having an average particle size of 20 nm (AEROSIL R972,
2.0 parts by weight Methylene chloride (first solvent) 69.3 parts by weight Methanol (second solvent) 17.5 parts by weight n-butanol (third solvent) 0.9 parts by weight The above cellulose acylate Solution 301B 0.9 parts by mass ――――――――――――――――――――――――――――――――――――

(Preparation of base layer dope 303B (cellulose acylate solution 303B))
Each component was put into a mixing tank with the composition shown below and dissolved by stirring to prepare a base layer dope 303B.
――――――――――――――――――――――――――――――――――――
Composition of base layer dope 303B ――――――――――――――――――――――――――――――――――――
Cellulose acetate with an acetyl substitution degree of 2.87 and a polymerization degree of 370
100.0 parts by mass Sucrose benzoate (benzoyl substitution degree 5.5)
3.0 parts by mass Sucrose acetate isobutyrate manufactured by Sigma-Aldrich
1.0 part by mass The above barbituric acid derivative (E) 6.0 parts by mass The above UV absorber D 2.3 parts by mass Methylene chloride (first solvent) 297.7 parts by mass Methanol (second solvent) 75. 4 parts by mass n-butanol (third solvent) 3.8 parts by mass ―――――――――――――――――――――――――――――――――― -

(Preparation of support side surface dope 304B)
1.3 parts by mass of the matting agent solution 302B prepared in the air layer side surface dope 301B and 99.3 parts by mass of the cellulose acylate solution 301B were mixed using an in-line mixer, and the support side surface dope was mixed. 304B was prepared.

(Casting)
Using the drum casting apparatus shown in FIG. 8, the base layer dope 303B (120 in FIG. 8) prepared above, the surface layer dope (air side surface layer dope 301B (121 in FIG. 8) and the support side) on both sides thereof Three layers of the surface layer dope 304B (122 in FIG. 8) were uniformly cast from a casting port onto a stainless casting support (support temperature −9 ° C.) 85 at the same time. Stripped in a state where the amount of residual solvent in the dope of each layer is about 70% by mass, fixed both ends in the width direction of the film with a pin tenter, and 1.28 in the lateral direction in a state of residual solvent amount of 3-5% by mass. The film was dried while being stretched twice. Then, it is further dried by conveying between rolls of a heat treatment apparatus, and cellulose acylate film No. 301B was obtained. The obtained cellulose acylate film No. The thickness of 301B was 55 μm (air side surface layer (121a in FIG. 8) 3 μm, base layer (120a in FIG. 8) 49 μm, support side surface layer (122a in FIG. 8) 3 μm), and the width was 1480 mm.

<1-5: Polarizing plate protective film No. Production of 301>
(Formation of iodine diffusion preventing layer (polymer B1 layer))
The above-mentioned cellulose acylate film No. On the band surface of 301B (the surface of the support-side surface layer 122a of the cellulose acylate film No. 301B that was in contact with the stainless steel casting support at the time of film formation), the coating solution Ba-2 for the iodine diffusion preventing layer. Was applied by a micro gravure coating method under conditions of a conveyance speed of 30 m / min. This was dried at 100 ° C. for 120 seconds to form an iodine diffusion preventing layer having a thickness of 5 μm.
Here, in the preparation of the composition Ba-2, as the solvent, the fd value of the cellulose acylate contained in the band layer and the fd value of the following polymer B1 (polymethyl methacrylate) are respectively Propyl acetate satisfying the relational expression [1] and the relational expression [2] was selected.
The cellulose acylate is the same as that used in Example 101, and the polymer B1 is the same type as that used in Example 101. Table 3 shows the calculated values of fd _polymerB1 and relational expressions [1] and [2] at this time.
Thus, polarizing plate protective film No. 1 provided with the iodine diffusion preventing layer 12 having a single layer structure shown in FIG. 301B was obtained.

<1-6: Production of polarizing plate>
(Preparation of active energy ray-curable adhesive composition 2)
Each component was mixed with the composition shown below, and the active energy ray hardening-type adhesive composition 2 was obtained.
――――――――――――――――――――――――――――――――――――
Composition of active energy ray curable adhesive composition 2 ――――――――――――――――――――――――――――――――――――
Cationic polymerizable compound A having the following structure 75.0 parts by mass Cationic polymerizable compound B having the following structure 20.0 parts by mass Cationic polymerizable compound C having the following structure 5.0 parts by mass Photocationic polymerization initiator:
Triarylsulfonium hexafluorophosphate 2.25 parts by mass ――――――――――――――――――――――――――――――――――――

(Production of polarizer)
A polyvinyl alcohol film having an average polymerization degree of 2400, a saponification degree of 99.9 mol% and a thickness of 60 μm was immersed in warm water at 30 ° C. for 60 seconds to swell. Next, the film was stretched to 3.5 times while being dyed in an iodine solution of 0.3% by mass (mass ratio: iodine / potassium iodide = 0.5 / 8) at 30 ° C. for 1 minute. Thereafter, the film was stretched until it was 6 times in total stretch ratio while being immersed in a 4% by mass boric acid aqueous solution at 65 ° C. for 0.5 minutes. After extending | stretching, it dried for 3 minutes in 70 degreeC oven, and obtained the 20-micrometer-thick polarizer. The moisture content of the polarizer was 13% by mass.

(Lamination)
The surface of the polarizing plate protective film 301B provided with the iodine diffusion preventing layer was subjected to corona treatment on the surface of the iodine diffusion preventing layer side. The active energy ray-curable adhesive composition 2 prepared above was applied to the surface of the iodine diffusion preventing layer subjected to the corona treatment using a bar coater.
Further, for the polarizing plate protective film 301A provided with an iodine diffusion preventing layer, after the corona treatment was performed on the surface on the iodine diffusion preventing layer side, the surface of the iodine diffusion preventing layer was similarly prepared as described above. The active energy ray-curable adhesive composition 2 was applied.
Then, the surface which apply | coated the active energy ray hardening-type adhesive composition of each film was bonded together on the one side surface of the polarizer, respectively. At this time, the transmission axis of the polarizer and the polarizing plate protective film No. The slow axis of 301A was parallel, and the transmission axis of the polarizer and the slow axis of 301B were perpendicular. Then, it heated at 50 degreeC using IR heater from both surfaces of the bonded film (polarizing plate protective film 301A and 301B).
Next, using a UV irradiation device with a belt conveyor (UV lamp uses “D bulb” manufactured by Fusion UV System Co., Ltd.), the polarizing plate protective film No. 1 was adjusted so that the integrated light amount was 250 mJ / cm ² . The active energy ray-curable adhesive composition was cured by irradiating ultraviolet rays from the 301A side.
Thereafter, it was dried with hot air at 70 ° C. for 3 minutes. 301 was obtained.

2. Example 302
In Example 302, a polarizing plate protective film No. 1 in which an iodine diffusion preventing layer was directly provided on one surface of the polarizer as follows. 302 (FIG. 1) and polarizing plates provided with the same were prepared.

<2-1: Production of polarizing plate>
(Lamination)
The surface of the polarizing plate protective film 301A provided with the iodine diffusion preventing layer was subjected to corona treatment on the surface of the iodine diffusion preventing layer side. The active energy ray-curable adhesive composition 2 prepared above was applied onto the surface of the iodine diffusion preventing layer subjected to the corona treatment using a bar coder.
Separately, the cellulose acetate film no. The air surface of 301B (the surface on the side opposite to the support-side surface layer 122a that was in contact with the stainless steel casting support during film formation) was subjected to corona treatment and then subjected to iodine on the surface subjected to corona treatment. Polarizing plate protective film No. provided with a diffusion preventing layer. In the same manner as 301A, the active energy ray-curable adhesive composition 2 prepared above was applied.
In this way, polarizing plate protective film No. 1 provided with an iodine diffusion preventing layer coated with the active energy ray-curable adhesive composition, respectively. 301A and cellulose acetate film no. 301B was produced.
Then, the surface which apply | coated the active energy ray hardening-type adhesive composition of each film was bonded together on the one side surface of the polarizer, respectively. At this time, the transmission axis of the polarizer and the polarizing plate protective film No. Arranged so that the slow axis of 301A was parallel. Then, it heated to 50 degreeC using IR heater from both surfaces of the bonded film (polarizing plate protective film No. 301A and cellulose acetate film No. 301B).
Next, using a UV irradiation device with a belt conveyor (UV lamp uses “D bulb” manufactured by Fusion UV System Co., Ltd.), the polarizing plate protective film No. 1 was adjusted so that the integrated light amount was 250 mJ / cm ² . The active energy ray-curable adhesive composition was cured by irradiating ultraviolet rays from the 301A side.
Thereafter, it was dried with hot air at 70 ° C. for 3 minutes. 302 was obtained.

3. Production of Comparative Example 401 In Comparative Example 401, a polarizing plate in which a cellulose acetate film was directly provided on both surfaces of a polarizer was produced as follows.
<3-1: Production of polarizing plate>
(Saponification treatment of polarizing plate protective film)
Cellulose acylate film no. 301A and cellulose acylate film no. Each 301B was immersed in a 2.3 mol / L sodium hydroxide aqueous solution at 55 ° C. for 3 minutes. This was washed in a room temperature water bath and neutralized at 30 ° C. with 0.05 mol / L sulfuric acid. Again, it was washed in a water bath at room temperature and further dried with hot air at 100 ° C. Thus, the cellulose acylate film No. 301A and cellulose acylate film no. The surface of 301B was saponified.

(Lamination)
Saponified cellulose acylate film no. The air surface 301A (the surface opposite to the support-side surface layer 122a that was in contact with the stainless steel casting support at the time of film formation) was attached to one side of the polarizer using a polyvinyl alcohol-based adhesive. Furthermore, saponified cellulose acylate film no. The air surface of 301B (the surface on the side opposite to the support side surface layer 122a that was in contact with the stainless steel casting support at the time of film formation) was attached to the surface on the opposite side of the polarizer using a polyvinyl alcohol-based adhesive. It was.
In this way, the polarizing plate No. 401 was produced.

4). Evaluation of Polarizing Plate Protective Film and Polarizing Plate Moisture permeability and adhesion for each polarizing plate protective film obtained above, and polarizing plate durability for each polarizing plate are the same as in each evaluation method of Example 101 above. And evaluated. The results are shown in Table 3.
For adhesion, the polarizing plate protective film No. The evaluation result was A for both 301A and 301B.
The sample used for polarizing plate durability evaluation was produced as follows.
Polarizing plate No. 301, no. 302 and Comparative Example polarizing plate No. No. 401, the cellulose acylate film No. of the protective film. The surface of 301A was affixed on the glass plate through the adhesive, and the sample (5 cm x 5 cm) was produced. The above configuration assumes that the surface of the cellulose acylate film disposed on the glass interface side is disposed on the liquid crystal cell side in an actual liquid crystal display device.

From the results in Table 3, the following can be understood.
That is, the polarizing plate protective film No. 1 of the present invention. 301 and 302 were excellent in interlayer adhesion between the iodine diffusion preventing layer and the cellulose acylate layer. Further, the polarizing plate protective film No. 1 of the present invention. When 301 and 302 were used for the polarizing plate, a decrease in the degree of polarization could be suppressed. Specifically, it is assumed that the polarizing plate protective film 301A of the present invention is used on the liquid crystal cell side, polarizing plate No. 302 is a polarizing plate No. 302. The polarizer durability was superior to 401. Furthermore, the polarizing plate protective film of the present invention is also applied to the polarizing plate protective film on the air side. Assuming that 301B is used, polarizing plate No. No. 301 was more excellent in polarizer durability.

[5. Examples 501 to 505]
In Examples 501 to 505, a polarizing plate protective film 10A (FIG. 1) provided with a two-layered iodine diffusion preventing layer 12 on one surface of a polarizer, and a polarizing plate provided with this polarizing plate protective film Each plate was prepared and its characteristics were evaluated.
First, a polarizing plate protective film 10A was produced.

1. Example 501
<1-1: Film Formation of Iodine Diffusion Prevention Layer>
(Preparation of Composition Ba-5 for Formation of Iodine Diffusion Prevention Layer)
Each component was mixed with the composition shown below, and filtered with a polypropylene filter having a pore diameter of 10 μm to prepare an iodine diffusion preventing layer forming composition Ba-5.
In the preparation of the composition Ba-5, as the solvent, the fd value of the cellulose acylate and the fd value of the following polymer B1 (polymethyl methacrylate) are respectively expressed by the above relational expression [1] and the above relation. Propyl acetate satisfying formula [2] was selected.
Cellulose acylate is the same as that used in Example 101, and polymer B1 is the same type (PMMA) used in Example 101. Therefore, in preparing the composition Ba-5, the calculated values of fd _cellulose, fd _solvent, and fd _{polymer B1} , and relational expressions [1] and [2] are the same as those in Example 101, and will be omitted.

――――――――――――――――――――――――――――――――――――
Composition of Composition Ba-5 for Iodine Diffusion Prevention Layer Formation ――――――――――――――――――――――――――――――――――――
Polymethylmethacrylate: Mitsubishi Rayon Dianal BR83
16.0 parts by mass Propyl acetate (solvent) 84.0 parts by mass ――――――――――――――――――――――――――――――――――――― -

(Preparation of Composition Ba-6 for Formation of Iodine Diffusion Prevention Layer)
Each component was mixed with the composition shown below, and filtered with a polypropylene filter having a pore size of 10 μm to prepare an iodine diffusion preventing layer forming composition Ba-6.
In the preparation of the composition Ba-6, as the solvent, the fd value of the cellulose acylate and the fd value of the following polymer B1 (polymethyl methacrylate) were respectively expressed by the above relational expression [1] and the above relation. Propyl acetate satisfying formula [2] was selected.
Cellulose acylate is the same as that used in Example 101, and polymer B1 is the same type (PMMA) used in Example 101. Therefore, in preparing the composition Ba-6, the calculated values of fd _cellulose, fd _solvent, and fd _{polymer B1} , and the relational expressions [1] and [2] are the same as those in Example 101, and will be omitted.

――――――――――――――――――――――――――――――――――――
Composition of composition Ba-6 for formation of iodine diffusion barrier layer ――――――――――――――――――――――――――――――――――――
Polymethylmethacrylate: Mitsubishi Rayon Dianal BR83
14.5 parts by mass The following matting agent solution 7 3.6 parts by mass Propyl acetate (solvent) 81.9 parts by mass ――――――――――――――――――――――――― ―――――――――――

The matting agent solution 7 used in the composition Ba-6 for forming an iodine diffusion preventing layer was prepared by charging each component with a composition shown below into a disperser and stirring to dissolve.
―――――――――――――――――――――――――――――――――――――
Composition of Matte Solution 7 ―――――――――――――――――――――――――――――――――――――
Silica particles having an average particle size of 20 nm (AEROSIL R972,
2.0 parts by mass of propyl acetate (solvent) 97.8 parts by mass of polymethyl methacrylate: Dianal BR83 manufactured by Mitsubishi Rayon Co., Ltd.
0.2 parts by mass ―――――――――――――――――――――――――――――――――――――

(Formation of iodine diffusion preventing layer (polymer B1 layer) 12)
Cellulose acetate film No. 1 prepared in Reference Example 101 On the surface of the band 101 (the surface of the support side surface 122a of the cellulose acylate film that was in contact with the casting support 85 made of stainless steel at the time of film formation) By the method, it apply | coated on conditions with a conveyance speed of 30 m / min. This was dried at 100 ° C. for 60 seconds to form a first layer of a polymer B1 layer having a thickness of 2.5 μm. Next, an iodine diffusion preventing layer coating solution Ba-6 was applied on the first layer by a slot die method. This was dried at 100 ° C. for 60 seconds to form a second layer having a thickness of 2.5 μm. In this way, a polymer B1 layer having a two-layer structure was formed.
The obtained polarizing plate protective film 10C provided with the iodine diffusion preventing layer was bonded to the polarizing plate protective film No. 501.

2. Example 502
In the preparation of the composition Ba-6 for forming the iodine diffusion preventing layer of Example 501, the same procedure as in Example 501 was conducted except that Mitsubishi Rayon's Dianal BR83 was changed to Mitsubishi Rayon's Dianal BR80. The polarizing plate protective film No. 502 was produced.

3. Example 503
In the preparation of the composition Ba-6 for forming iodine diffusion preventing layer of Example 501, Example except that Mitsubishi Rayon Dianal BR83 was changed to Mitsubishi Rayon Dianal BR80 and the solvent was changed to methyl acetate. In the same manner as in Example 501, polarizing plate protective film No. 503 was produced.
When the solvent is changed, the fd value satisfies the relational expression [1] and the relational expression [2] with respect to the fd value of cellulose acylate and the fd value of the following polymer B2 (polymethyl methacrylate). No methyl acetate was selected (see Comparative Example 207 for specific values).

4). Example 504
In the preparation of the composition Ba-6 for forming the iodine diffusion preventing layer of Example 501, the dialal BR83 manufactured by Mitsubishi Rayon Co. was changed to the dialal BR80 manufactured by Mitsubishi Rayon Co., and the solvent was changed to methyl acetate, and iodines The polarizing plate protective film No. 504 of Example 504 was the same as Example 501 except that the thickness of the diffusion prevention layer (the thickness of the first layer was 4 μm and the thickness of the second layer was 1 μm) was changed. 504 was produced.

5. Example 505
In preparation of the composition Ba-6 for forming an iodine diffusion preventing layer of Example 501, Mitsubishi Rayon's Dianal BR83 was changed to Mitsubishi Rayon's Dianal BR80, and the solvent was changed to methyl acetate. The amount of the additive (iodine diffusion prevention layer forming composition Ba-2 used in the composition Ba-2) is shown in Table 4, and the iodine diffusion prevention layer forming composition Ba-5 and iodine diffusion prevention layer formation Example 501 except that it is contained in the composition Ba-6 and the thickness of the iodine diffusion preventing layer (the thickness of the first layer is 4 μm and the thickness of the second layer is 1 μm) is changed. , Polarizing plate protective film No. of Example 505. 505 was produced.

6). Production of Polarizing Plate Next, a polarizing plate was produced using each obtained polarizing plate protective film.
In the production of the polarizing plate of Example 101, the polarizing plate protective film No. Polarizing plate Nos. 501 to 505 of Examples 501 to 505 are the same as Example 101 except that 501 to 505 are used. 501 to 505 were produced.

7). Evaluation of Polarizing Plate Protective Film and Polarizing Plate Moisture permeability and adhesion for each polarizing plate protective film obtained above, and polarizing plate durability for each polarizing plate are the same as in each evaluation method of Example 101 above. And evaluated. Further, the surface smoothness of each polarizing plate protective film and the punching characteristics of each polarizing plate were evaluated as follows. The results are shown in Table 4.

<7-1: Film surface: Surface smoothness>
An area of 620 μm × 465 μm is used for the central portion of the surface of the polarizing plate protective film provided with the iodine diffusion preventing layer on the iodine diffusion preventing layer side, using Bart Scan 2.0 (model number: R5300H) manufactured by Ryoka System. Were observed at three arbitrary locations with a resolution of 640 × 480 pixels, and the smoothness of the surface was evaluated by the presence or absence of irregularities with an elevation difference of 0.1 μm or more.
Here, the height difference of the unevenness was obtained as the difference between the adjacent bottom and height in the 620 μm × 465 μm region of the surface.
The evaluation criteria are “no unevenness” when no unevenness with an elevation difference of 0.1 μm or more exists in all of the above regions, and one unevenness with an elevation difference of 0.1 μm or more in one of the above regions. However, when it was present, it was defined as “with unevenness”.

<7-2: Suitability for punching polarizing plate>
Polarizing plate No. Each of 501 to 505 was stored for 24 hours in an environment of 80 ° C. and a relative humidity of 10% or less, and then conditioned for 24 hours in an environment of 25 ° C. and a relative humidity of 10%. One sample of 40 mm × 40 mm square was punched from the humidity-controlled polarizing plate using a Thomson blade with a blade angle of 43 ° from the cellulose acylate layer side toward the iodine diffusion preventing layer. About the sample punched out, the following standards evaluated the grade of peeling between each layer which comprises a polarizing plate.
The maximum value of the depth of the peeled portion of the sample (the shortest straight line distance from the edge of each side to the tip of the peeled portion in the direction toward the inside of the sample)
A: Less than 1.0 mm B: 1.0 mm or more and less than 1.5 mm C: 1.5 mm or more and 5.0 mm or less

From the results in Table 4, the following can be understood.
That is, the polarizing plate protective film No. 1 of the present invention. All of 501 to 505 were excellent in interlayer adhesion between the iodine diffusion preventing layer and the cellulose acylate layer. Further, the polarizing plate protective film No. 1 of the present invention. 501 to 505 were found to be excellent in polarizer durability when used for polarizing plates.
Furthermore, Examples 502 to 505 using polymethyl methacrylate having a weight average molecular weight of 95,000 for the second layer are more suitable for punching a polarizing plate than Example 501 using polymethyl methacrylate having a weight average molecular weight of 40000 for the second layer. It was excellent. In particular, Example 505 containing a fluorosurfactant in the polymer layer B1 was preferred because it had higher film surface smoothness than Example 504 containing no fluorosurfactant.

[6. Examples 701 to 704]
In Examples 701 to 704, a polarizing plate protective film (FIG. 1) in which an iodine diffusion preventing layer was directly provided on one surface of a polarizer, and a polarizing plate provided with this polarizing plate protective film were prepared. The characteristics were evaluated.

1. Example 701
<1-1: Preparation of Composition Ba-8 for Formation of Iodine Diffusion Prevention Layer>
Each component was mixed with the composition shown below, and filtered with a polypropylene filter having a pore size of 10 μm to prepare an iodine diffusion preventing layer forming composition Ba-8.
In the preparation of the composition Ba-8, as the solvent, the fd value of the cellulose acylate and the fd value of the following polymer B1 (polymethyl methacrylate) were respectively expressed by the above relational expression [1] and the above relation. Propyl acetate satisfying formula [2] was selected.
Cellulose acylate is the same as that used in Example 101, and polymer B1 is the same type (PMMA) used in Example 101. Therefore, in preparing the composition Ba-8, the calculated values of fd _cellulose, fd _solvent, and fd _{polymer B1} , and the relational expressions [1] and [2] are the same as those in Example 101, and will be omitted.

――――――――――――――――――――――――――――――――――――
Composition of Composition Ba-8 for Iodine Diffusion Prevention Layer Formation ―――――――――――――――――――――――――――――――――――
Polymethylmethacrylate: Mitsubishi Rayon Dianal BR80
8.0 parts by mass Fluoropolymer F having the above structure 0.004 parts by mass Propyl acetate (solvent) 92.0 parts by mass ――――――――――――――――――――――― ―――――――――――――

<1-2: Preparation of matting agent solution 9>
Each component was put into a disperser with the composition shown below and dissolved by stirring to prepare a matting agent solution 9.
――――――――――――――――――――――――――――――――――――
Composition of Matting Agent Solution 9 ――――――――――――――――――――――――――――――――――――
Silica particles having an average particle size of 20 nm (AEROSIL NX90S,
Nippon Aerosil Co., Ltd.) 2.0 parts by weight Cellulose acetate propionate: CAP-482-20 by Eastman Chemical Co. 4.0 parts by weight Propyl acetate (solvent) 96.0 parts by weight ―――――――――――――――――――――――――

<1-3: Preparation of composition Ba-10 for polarizer side easily bonding layer formation>
Each component was mixed with the composition shown below, and filtered with a polypropylene filter having a pore diameter of 10 μm to prepare an easy-adhesion layer forming composition Ba-10.
――――――――――――――――――――――――――――――――――――
Composition of easy adhesive layer forming composition Ba-10 ――――――――――――――――――――――――――――――――――――
Cellulose acetate propionate: CAP-482-20 manufactured by Eastman Chemical Co. 7.8 parts by mass The above matting agent solution 9 3.6 parts by mass Propyl acetate (solvent) 88.6 parts by mass ――――――――― ――――――――――――――――――――――――――
CAP-482-20 manufactured by Eastman Chemical Co. is cellulose acetate propionate having an acetyl substitution degree of 0.18 and a propionyl substitution degree of 2.47.

<1-4: Formation of iodine diffusion preventing layer and polarizer side easy adhesion layer>
Cellulose acetate film No. 1 prepared in Reference Example 101 On the band surface of 101 (the surface of the cellulose acylate film support surface layer 122a in contact with the cast casting support 85 made of stainless steel at the time of film formation), an iodine diffusion preventing layer coating solution Ba-8 By the method, it apply | coated on the conditions of conveyance speed 30m / min. This was dried at 100 ° C. for 60 seconds to form a polymer B1 layer 12 having a thickness of 4.5 μm. Thus, a polarizing plate protective film 10A shown in FIG. 1 was produced.
Next, the easy-adhesion layer coating solution Ba-10 was applied on the polymer B1 layer 12 by a slot die method. This was dried at 100 ° C. for 60 seconds to form a polarizer-side easy-adhesion layer having a thickness of 0.5 μm.
The obtained polarizing plate protective film with a polarizer-side easy-adhesion layer was bonded to the polarizing plate protective film No. 701 of Example 701. 701.

<1-5: Production of polarizing plate>
In preparation of the polarizing plate of Comparative Example 401, polarizing plate protective film No. Instead of 301B (air interface side polarizing plate protective film), polarizing plate protective film No. 701, the polarizer easy-adhesion layer was in contact with the polarizer, and the slow axis of the cellulose acylate film was changed to be perpendicular to the transmission axis of the polarizer. Polarizing plate No. of the invention. 701 was produced.

2. Example 702
The same procedure as in Example 701 was performed except that CAP-482-20 added to composition Ba-10 for easily bonding layer formation in Example 701 was changed to CAB-171-15 manufactured by Eastman Chemical Co., Ltd. Polarizing plate protective film No. 702 of Example 702 702 and polarizing plate No. 702. 702 were produced respectively.
CAB-171-15 manufactured by Eastman Chemical Co. is cellulose acetate butyrate having an acetyl substitution degree of 2.0 and a butyryl substitution degree of 0.7.

3. Example 703
In Example 702, it is the same as Example 702 except having added the fluorine-type surfactant (the said fluorine-type polymer F) of the said structure with the addition amount shown in Table 5 to composition Ba-10 for easily bonding layer formation. The polarizing plate protective film No. of Example 703 was obtained. 703, and polarizing plate No. 703 were produced.

4). Example 704
In Example 701, the polarizing plate protective film No. 704 in Example 704 was obtained in the same manner as in Example 701 except that the composition Ba-10 for easily bonding layer formation was not applied. 704 and polarizing plate No. 704. 704 were produced.

5. Evaluation of Polarizing Plate The polarizing plate durability of each polarizing plate obtained above was evaluated in the same manner as each evaluation method of Example 101. Moreover, the peeling force was evaluated as follows about each polarizing plate. The results are shown in Table 5.

<5-1: Peeling strength of polarizing plate>
Polarizing plate No. Each of the polarizing plate protective film No. On the 701-704 side, it stuck on the glass substrate through the adhesive agent, and produced the test body. About this test body, using the Tensilon universal material testing machine (model number: RTC-1210A, manufactured by Orientec Co., Ltd.), the polarization in the polarizing plate attached at a peeling angle of 90 ° and a peeling speed of 300 m / min. The peel strength (N / 25 mm) when the child was peeled from the polarizing plate protective film was measured.

From the result of Table 5, polarizing plate protective film No. of this invention. It turned out that the polarizing plate of this invention provided with 701-704 is excellent in durability. Furthermore, Examples 701 to 703 in which the polarizer-side easy-adhesion layer is provided on the polymer layer 12 have higher adhesion between the layers constituting the polarizing plate than Example 704 in which the polarizer-side easy-adhesion layer is not provided. It was shown to be preferable.
Polarizing plate protective film No. 701 to 704 all had high interlayer adhesion between the iodine diffusion preventing layer and the cellulose acylate layer, and had a moisture permeability in the above range.

10A to 10D Polarizing plate protective film 11 Cellulose ester layer 12 Polymer B1 layer 13 Polymer B2 layer 15A and 15B Polarizing plate 16 Polarizer 17 Cycloolefin film 20 Liquid crystal display device 21 First (upper) polarizing plate 22 First polarizing plate absorption axis Direction 23 first (upper liquid crystal cell) electrode substrate 24 liquid crystal layer 25 second (lower liquid crystal cell) electrode substrate 26 second (lower) polarizing plate 27 second polarizing plate absorption axis direction 70 casting film 85 casting Support (band)
89 Casting die 120 Dope for base layer 121 Dope for air side surface layer 122 Dope for support side surface layer 120a Base layer (core layer)
121a Air side surface layer (first skin layer)
122a Support side surface layer (second skin layer)

Claims (11)

A cellulose ester layer containing a cellulose ester, and a polymer B1 layer containing a polymer B1 adjacent to at least one surface of the cellulose ester layer;
The polymer B1 contains the following repeating unit [a]:
A composition in which the polymer B1 layer contains, on the surface of the cellulose ester layer, the polymer B1 and a solvent in which fd defined by the following formula I satisfies the following relational expressions [1] and [2]. Apply
85 ° C., 85% relative humidity conditions, the polarizer protective film moisture permeability is 1600 g / ^{m 2} or less 100 g / ^{m 2} or more at 6 hours.
[A]: Repeating unit in which solubility parameter δt calculated by Hoy method is 13.5 or more and less than 20.0 Relational expression [1] | fd _solvent −fd _cellulose | ≦ 0.050
Relational expression [2] | fd _solvent −fd _polymerB1 | ≦ 0.050
In the relational expressions [1] and [2], fd _solvent represents the fd value of the solvent, fd _cellulose represents the fd value of the cellulose ester, and fd _polymerB1 represents the fd value of the polymer B1.
Here, the fd value is defined by the following formula I.
Formula I fd = δd / (δd + δp + δh)
In Formula I, δd, δp, and δh are a term corresponding to the London dispersion force, a term corresponding to the force between dipoles, and a term corresponding to the hydrogen bonding force, respectively, with respect to the solubility parameter δt calculated by the Hoy method. Fd represents the ratio of δd to the sum of δd, δp, and δh. The polarizing plate protective film of Claim 1 in which the said polymer B1 contains the repeating unit of following [b].
[B]: Repeating unit whose solubility parameter δt calculated by the Hoy method is 20.0 or more and 26.0 or less A polymer B2 layer containing polymer B2 adjacent to the surface of the polymer B1 layer opposite to the cellulose ester layer;
The polarizing plate protective film according to claim 2, wherein the polymer B2 contains the following repeating unit [a] and does not contain the repeating unit [b].
[A]: Repeating unit in which solubility parameter δt calculated by Hoy method is 13.5 or more and less than 20.0 [b]: Solubility parameter δt calculated by Hoy method is 20.0 or more and 26.0 or less Repeat unit   The polarizing plate protective film according to any one of claims 1 to 3, wherein the polymer B1 layer is formed by coating the composition on the surface of the cellulose ester layer. A composition containing, on at least one surface of a cellulose ester layer containing a cellulose ester, the polymer B1 and a solvent in which fd defined by the following formula I satisfies the following relational expressions [1] and [2]. The manufacturing method of the polarizing plate protective film of any one of Claims 1-3 including the process of applying a thing.
Relational expression [1] | fd _solvent -fd _cellulose | ≦ 0.050
Relational expression [2] | fd _solvent −fd _polymerB1 | ≦ 0.050
In the relational expressions [1] and [2], fd _solvent represents the fd value of the solvent, fd _cellulose represents the fd value of the cellulose ester, and fd _polymerB1 represents the fd value of the polymer B1.
Here, the fd value is defined by the following formula I.
Formula I fd = δd / (δd + δp + δh)
In Formula I, δd, δp, and δh are a term corresponding to the London dispersion force, a term corresponding to the force between dipoles, and a term corresponding to the hydrogen bonding force, respectively, with respect to the solubility parameter δt calculated by the Hoy method. Fd represents the ratio of δd to the sum of δd, δp, and δh.   The polarizing plate which has a polarizer and the polarizing plate protective film of Claim 1 or 2 provided in the at least one surface of the said polarizer.   The polarizing plate according to claim 6, wherein the polymer B1 layer of the polarizing plate protective film is disposed on the surface side of the polarizer.   The polarizing plate which has a polarizer and the polarizing plate protective film of Claim 3 provided in the at least one surface of the said polarizer.   The polarizing plate according to claim 8, wherein the polymer B2 layer of the polarizing plate protective film is disposed on the surface side of the polarizer.   When the polarizing plate protective film is provided on one surface of the polarizer, the polarizer has a cycloolefin film containing a cycloolefin polymer on the surface opposite to the polarizing plate protective film. The polarizing plate of any one of 6-9.   The image display apparatus which has a polarizing plate of any one of Claims 6-10.

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