WO2017115784A1

WO2017115784A1 - Polarizer protection film and method for manufacturing same, polarizer, and liquid-crystal display device

Info

Publication number: WO2017115784A1
Application number: PCT/JP2016/088852
Authority: WO
Inventors: 伸隆深川; 真裕美野尻; 遊内藤; 一男蒲原; 寛野副; 佐野　直樹; 浩之野田
Original assignee: 富士フイルム株式会社
Priority date: 2015-12-28
Filing date: 2016-12-27
Publication date: 2017-07-06
Also published as: JPWO2017115784A1; JP6654203B2

Abstract

A polarizer protection film having a layer containing a cellulose ester, a layer containing a cyclic polyolefin, and a layer containing a polar group-modified polyolefin between the layer containing a cellulose ester and the layer containing a cyclic polyolefin, wherein the polarizer protection film has, in between the layer containing a cellulose ester and the layer containing a polar group-modified polyolefin, a mixture layer containing a cellulose ester and a polar group-modified polyolefin and having a film thickness calculated on the basis of the oxygen atom content measured by X-ray electron spectroscopy of 0.20-2.0 μm. A method for manufacturing the polarizer protection film. A polarizer and an image display device in which the polarizer protection film is used.

Description

Polarizing plate protective film, method for producing the same, polarizing plate and liquid crystal display device

The present invention relates to a polarizing plate protective film, a manufacturing method thereof, and a polarizing plate and a liquid crystal display device.

Image display devices represented by electroluminescence display (ELD) and liquid crystal display device (LCD) have been diversified in recent years, including outdoor use, and have a harsh environment such as a high temperature and high humidity environment compared to the past. Opportunities to use below are increasing. Therefore, there is a demand for performance that maintains image quality even in such a harsh environment. Furthermore, the image display device is also required to be thin. In order to meet this requirement, if the thickness of the members constituting the image display device is reduced, the above-described deterioration in image quality becomes significant.
The decrease in image quality in the image display device is considered to be caused by moisture penetrating into the image display device and degrading the polarizer. Therefore, as a film that prevents the penetration of moisture into the image display device and prevents the deterioration of the polarizer, there is a polarizing plate protective film provided with a layer that reduces moisture transmission, that is, a low moisture permeable layer on the substrate. Proposed.

However, since the low moisture-permeable layer has insufficient adhesion to a substrate having high moisture permeability such as a cellulose ester film, it is easily peeled off at the lamination interface. Therefore, as a film for solving such a problem of poor adhesion, Patent Document 1 discloses a hydrophilic resin base material, an intermediate layer, and a hydrophobic coating layer that satisfy a specific relationship with respect to the solubility parameter. The functional film which has in order and has further the mixed area | region of an intermediate | middle layer and a coating layer is described.
Patent Document 2 includes a cured product of a resin composition containing a polyolefin resin modified with an unsaturated carboxylic acid or the like and a terpene resin on a transparent resin substrate made of a triacetyl cellulose resin substrate. A barrier laminate for an optical film having a primer layer and a barrier layer made of a resin composition containing a cycloolefin resin and a terpene resin in this order is described.
Further, Patent Document 3 discloses a coating obtained from an aqueous dispersion containing a base material layer made of a cellulose ester resin and an acid-modified polyolefin resin having an unsaturated carboxylic acid component content of 0.1 to 10% by mass. A laminated body is described in which at least a primer layer made of a film and a cyclic polyolefin resin coat layer are in this order.

JP 2014-226844 A Japanese Unexamined Patent Publication No. 2015-0667748 JP 2014-240174 A

Incidentally, the polarizing plate protective film is usually cut by punching or the like according to the panel size of the image display device. However, a film having a low moisture-permeable layer or a hydrophobic coating layer as described above may cause problems during processing. For example, peeling or cracking at the lamination interface of each layer, which occurs at the edge (edge) of the film by cutting, can be mentioned. When such a problem occurs, it is currently used by removing the part where the problem has occurred due to processing such as polishing, reducing the yield and increasing the manufacturing cost, that is, from the viewpoint of the processing characteristics of the polarizing plate Therefore, there was room for improvement.

An object of the present invention is to provide a polarizing plate protective film having a small moisture permeability and excellent adhesion, and further capable of improving the deterioration of the polarizer and the processing characteristics of the polarizing plate, and a method for producing the same.
Moreover, this invention makes it a subject to provide the polarizing plate and image display apparatus which used this polarizing plate protective film.

As a result of intensive studies, the present inventors produce a laminate having a layer containing a cellulose ester, a layer containing a polyolefin modified with a polar group, and a layer containing a cyclic polyolefin in this order. In forming a layer containing a polyolefin modified with the above polar group using a solvent satisfying the relationship of the following relational expression [1] on the layer containing the cellulose ester, It has been found that a mixed layer containing a polyolefin modified with a polar group and a cellulose ester is formed with a predetermined film thickness between the containing layer and the layer containing the cellulose ester. Furthermore, the laminated body in which this mixed layer is formed exhibits small moisture permeability and strong interlayer adhesion. Therefore, when this laminated body is used as a polarizing plate protective film, the polarizer is deteriorated even under high temperature and high humidity conditions. It has also been found that it exhibits excellent performance against inhibition (improvement) and can improve the processing characteristics of the polarizing plate. The present invention has been further studied and completed based on these findings.

The above-described problems of the present invention have been solved by the following means.
<1> Polarizing plate protection having a layer containing a cellulose ester, a layer containing a cyclic polyolefin, a layer containing a cellulose ester and a layer containing a cyclic polyolefin, and a layer containing a polar group-modified polyolefin A film,
Calculated based on the oxygen atom content measured by X-ray electron spectroscopy, containing cellulose ester and polar group-modified polyolefin between the layer containing cellulose ester and the layer containing polar group-modified polyolefin The polarizing plate protective film which has a mixed layer with which the film thickness to satisfy | fill the relationship of a following formula (T1).
Formula (T1): 0.20 μm ≦ film thickness ≦ 2.0 μm

<2> The polarizing plate protective film according to <1>, wherein the polar group includes at least one of a carboxy group and a hydroxyl group.

<3> The polar group-modified polyolefin is a carboxylic acid-modified styrene-olefin copolymer, and the carboxylic acid-modified styrene-olefin copolymer has a repeating unit derived from a styrene compound to a repeating unit derived from an olefin compound. The polarizing plate protective film according to <1> or <2>, which is contained in an amount of 1 mol% to 20 mol% and an acid value defined below is 1 to 100.
Acid value: Mass of potassium hydroxide required to neutralize per gram of carboxylic acid-modified styrene-olefin copolymer (mg)

<4> The polarizing plate protective film according to any one of <1> to <3>, wherein the polar group-modified polyolefin has a glass transition temperature lower than that of the cellulose ester and the cyclic polyolefin.
<5> Polarizing plate protection having a layer containing a cellulose ester, a layer containing a cyclic polyolefin, and a layer containing a cellulose ester and a layer containing a cyclic polyolefin between a layer containing a cyclic polyolefin A method of manufacturing a film comprising:
A polarizing plate protective film for forming a layer containing a polar group-modified polyolefin by applying a forming liquid containing a polar group-modified polyolefin and a solvent satisfying the following relational expression [1] on the cellulose ester-containing layer Production method.
Relational expression [1]: | fd _solvent -fd _cellulose | ≦ 0.10
In the relational expression [1], fd _solvent represents the fd value of the solvent, and fd _cellulose represents the fd value of the cellulose ester.
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. Indicates.

<6> A method for producing a polarizing plate protective film according to any one of <1> to <4> above,
A polarizing plate protective film for forming a layer containing a polar group-modified polyolefin by applying a forming liquid containing a polar group-modified polyolefin and a solvent satisfying the following relational expression [1] on the cellulose ester-containing layer Production method.
Relational expression [1]: | fd _solvent -fd _cellulose | ≦ 0.10
In the relational expression [1], fd _solvent represents the fd value of the solvent, and fd _cellulose represents the fd value of the cellulose ester.
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. Indicates.
<7> A polarizing plate comprising the polarizing plate protective film according to any one of <1> to <4> and a polarizer.
The polarizing plate as described in <7> which arrange | positioned the layer containing the cyclic polyolefin of the <8> polarizing plate protective film to the polarizer side.
<9> An image display device having the polarizing plate according to <7> or <8>.

The present invention can provide a polarizing plate protective film having a small moisture permeability and excellent adhesion, and further capable of improving the deterioration of the polarizer and the processing characteristics of the polarizing plate. Moreover, this invention can provide the method which can manufacture suitably the polarizing plate protective film which has said outstanding effect. Furthermore, the present invention can provide a polarizing plate exhibiting excellent processing characteristics and high durability even under high-temperature and high-humidity conditions, using the polarizing plate protective film that exhibits the above-described excellent effects. Furthermore, the present invention can provide an image display device that exhibits high durability even under high-temperature and high-humidity conditions by using the polarizing plate protective film that exhibits the above-described excellent effects.
The above and other features and advantages of the present invention will become more apparent from the following description, with reference where appropriate to the accompanying drawings.

FIG. 1 is a cross-sectional view showing a preferred example of the polarizing plate protective film of the present invention, including a schematic enlarged view of a circular portion A in the layer. FIG. 2A is a cross-sectional view showing a preferred example of the polarizing plate of the present invention. FIG. 2B is a cross-sectional view showing another preferred example of the polarizing plate of the present invention. FIG. 3 is a schematic view showing an outline of a liquid crystal display device provided with a polarizing plate incorporating the polarizing plate protective film of the present invention. FIG. 4 is a chart showing a depth direction profile for the oxygen atomic ratio when the polarizing plate protective film of Example 101 is subjected to X-ray photoelectron spectroscopy (XPS). FIG. 5 is a chart showing a depth profile for the oxygen atom ratio when the polarizing plate protective film of Example 109 was analyzed by X-ray photoelectron spectroscopy.

In the present specification, a numerical range expressed using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.
In the present specification, when “(meth) acrylate” is described, it means acrylate, metaacrylate, or both.

In the present specification, the indication of the compound includes not only the compound itself but also its salt and its ion. Moreover, what changed the structure in part within the range which does not impair the target effect is included. Moreover, about the compound which does not specify substituted or unsubstituted, the thing which has arbitrary substituents is included in the range which does not impair the target effect. The same applies to a substituent or a linking group (hereinafter referred to as a substituent or the like).
In the present specification, when there are a plurality of substituents indicated by a specific symbol, or when a plurality of substituents are specified simultaneously, the respective substituents are the same or different unless otherwise specified. May be. The same applies to the definition of the number of substituents and the like. Further, when a plurality of substituents and the like are adjacent (particularly adjacent), they may be connected to each other to form a ring unless otherwise specified.
When the number of carbon atoms in the group is limited, the number of carbon atoms in the group means the total number of carbon atoms including substituents.

In this specification, when only described as a substituent, the substituent selected from the following substituent group Z is mentioned. In addition, when only a specific group (for example, an alkyl group) is described, preferred ranges and specific examples of the corresponding group (alkyl group) in the following substituent group Z are applied.
In the present invention, when a certain group can take a non-cyclic skeleton and a cyclic skeleton, the certain group includes a non-cyclic skeleton group and a cyclic skeleton group unless otherwise specified. 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 atoms forming the cyclic skeleton in the group of the cyclic skeleton is 3 or more, and preferably 5 or more, regardless of the lower limit of the number of carbon atoms specifically described in the certain group.

<Substituent group Z>
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, ethyl, isopropyl, tert-butyl, n-octyl, n-decyl, n -Hexadecyl, cyclopropyl, cyclopentyl, cyclohexyl, etc.), alkenyl groups (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms such as vinyl, allyl, 2 -Butenyl, 3-pentenyl and the like), alkynyl groups (preferably having 2 to 20, more preferably 2 to 12, particularly preferably 2 to 8 carbon atoms, such as propargyl and 3-pentynyl). An aryl group (preferably having 6 to 30 carbon atoms, more preferably 6 to 20 carbon atoms, particularly preferably 6 to 1 carbon atoms). For example, phenyl, biphenyl, naphthyl, etc.), an amino group (preferably having 0 to 20, more preferably 0 to 10, particularly preferably 0 to 6 carbon atoms such as amino, methylamino, Dimethylamino, diethylamino, dibenzylamino, etc.), alkoxy groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 12, particularly preferably 1 to 8, such as methoxy, ethoxy, butoxy, etc.) An aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms such as phenyloxy and 2-naphthyloxy). An acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms; Cetyl, benzoyl, formyl, pivaloyl, etc.), alkoxycarbonyl groups (preferably having 2-20 carbon atoms, more preferably 2-16, particularly preferably 2-12, such as methoxycarbonyl, ethoxycarbonyl, etc. An aryloxycarbonyl group (preferably having 7 to 20 carbon atoms, more preferably 7 to 16, and particularly preferably 7 to 10, such as phenyloxycarbonyl), an acyloxy group ( Preferably it has 2 to 20 carbon atoms, more preferably 2 to 16 and particularly preferably 2 to 10, for example, acetoxy, benzoyloxy, etc.), acylamino group (preferably 2 to 20 carbon atoms, more Preferably it is 2 to 16, particularly preferably 2 to 10, for example acetylamino And benzoylamino. ), An alkoxycarbonylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 and particularly preferably 2 to 12, such as methoxycarbonylamino), an aryloxycarbonylamino group (preferably Has 7 to 20 carbon atoms, more preferably 7 to 16 carbon atoms, particularly preferably 7 to 12 carbon atoms, such as phenyloxycarbonylamino, and the like, and a sulfonylamino group (preferably having 1 to 20 carbon atoms, more Preferably 1 to 16, particularly preferably 1 to 12, such as methanesulfonylamino, benzenesulfonylamino, etc.), sulfamoyl group (preferably having 0 to 20 carbon atoms, more preferably 0 to 16, particularly Preferably it is 0 to 12, for example, sulfamoyl, methylsulfamoyl, Methylsulfamoyl, phenylsulfamoyl, etc.), carbamoyl groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, such as carbamoyl, methylcarbamoyl, And diethylthiocarbamoyl, phenylcarbamoyl, etc.), alkylthio groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, such as methylthio and ethylthio). An arylthio group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms, particularly preferably 6 to 12 carbon atoms such as phenylthio), a sulfonyl group (preferably having 1 to 20 carbon atoms, More preferably 1 to 16, particularly preferably 1 to 12, such as mesyl, Syl, etc.), sulfinyl groups (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, such as methanesulfinyl, benzenesulfinyl, etc.), 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, methylureido, phenylureido and the like), phosphoramide 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 phosphoric acid amide and phenyl phosphoric acid amide)), hydroxyl group, mercapto group, halogen atom (For example, fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxy group, A tro group, a hydroxamic acid group, a sulfino group, a hydrazino group, an imino group, a heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms such as a nitrogen atom, an oxygen atom, A sulfur atom is mentioned, 5-membered ring or 6-membered ring or these condensed rings are preferable. Specific examples include imidazolyl, pyridyl, quinolyl, furyl, piperidyl, morpholino, benzoxazolyl, benzimidazolyl, benzthiazolyl, and the like. ) And a silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, particularly preferably 3 to 24 carbon atoms such as trimethylsilyl and triphenylsilyl).
These substituents may be further substituted. Moreover, when there are two or more substituents, they may be the same or different, and may be connected to each other to form a ring.

A preferred embodiment of the present invention will be described below.

[Polarizing plate protective film]
As shown in FIG. 1, a polarizing plate protective film 10 as a preferable example of the present invention includes a layer (also referred to as a cellulose ester layer) 11 containing a cellulose ester and a ring on one surface of the cellulose ester layer 11. A layer containing polyolefin (also referred to as a cyclic polyolefin layer) 12, a layer containing polar group-modified polyolefin (also referred to as a polar group-modified polyolefin layer) 13 between the cellulose ester layer 11 and the cyclic polyolefin layer 12, cellulose It has a mixed layer 14 between the ester layer 11 and the polar group-modified polyolefin layer 13. As will be described later, the mixed layer contains a cellulose ester and a polar group-modified polyolefin.
Further, the polarizing plate protective film 10 may have a mixed layer (mixed region) formed by mixing the polar group-modified polyolefin and the cyclic polyolefin between the polar group-modified polyolefin layer 13 and the cyclic polyolefin layer 12. Good.
In the present invention, the respective layers may be laminated adjacent to each other or may be laminated via other layers. In the polarizing plate protective film 10, the cellulose ester layer 11, the mixed layer 14, and the polar group-modified polyolefin layer 13 are laminated adjacent to each other. In the present invention, the term “adjacently laminated” means that the two adjacent layers are directly laminated (overlaid) without any other 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 mixed layer 14, the polar group-modified polyolefin layer 13, and the cyclic polyolefin layer 12 may be laminated on both surfaces of the cellulose ester layer 11 in this order. Further, the surface of the cyclic polyolefin layer 12 may have various functional layers specialized for a specific function. As such a functional layer, for example, a hard coat layer, an antireflection layer, a light scattering layer, an antifouling layer, an antistatic layer, or a cyclic polyolefin or a polar group-modified polyolefin, which will be described later, is less than 50% by mass. The layer to contain is mentioned.
Usually, the cellulose ester layer shows hydrophilicity and the cyclic polyolefin layer shows hydrophobicity. Therefore, both layers have low affinity and cannot secure sufficient adhesion. However, the polarizing plate protective film of the present invention has a mixed layer and a polar group-modified polyolefin layer in this order between the cellulose ester layer and the cyclic polyolefin layer. Thereby, even if it is a polarizing plate protective film which has a cellulose-ester layer and a cyclic polyolefin layer, high adhesiveness is shown, maintaining a water vapor transmission rate.

<Layer containing cellulose ester>
The cellulose ester layer 11 is a layer containing 50 mass% or more of cellulose ester in the layer 11. 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 especially preferable.
As the cellulose ester contains more cellulose ester, the cellulose ester exhibits higher adhesion to the polar group-modified polyolefin layer 13 described later. Therefore, the upper limit of the content of the cellulose ester is not particularly limited and can be 100% by mass, but for example, 99% by mass or less is preferable.

-Cellulose ester-
If the cellulose ester contained in a cellulose-ester layer is a cellulose ester used for manufacture of a cellulose-ester film, it can be especially used without being restrict | limited. The cellulose ester is preferably selected from those having fd satisfying the relational expression [1] described later in relation to the solvent used when forming the polar group-modified polyolefin layer 13. fd will be described later.

The glucose unit constituting cellulose and having 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, conifer pulp). Any cellulose obtained from any raw material cellulose can be used, and in some cases, these may be used in combination. The raw material cellulose is, for example, Marusawa, Uda, “Plastic Materials Course (17) Fibrous Resin”, Nikkan Kogyo Shimbun (published in 1970), or Japan Institute of Invention and Technology Publication No. 2001-1745 (page 7). To page 8) can be used.

The cellulose ester is not particularly limited as long as it is an esterified product of the above-mentioned cellulose-derived hydroxy group. Among them, cellulose acylate obtained by acylating a part of the hydroxy group in the glucose unit is preferable.
The acyl substitution degree (hereinafter, sometimes simply referred to as “substitution degree”) indicates the degree of acylation of the hydroxy group bonded to the 2-position, 3-position and 6-position of the glucose unit in cellulose. When the hydroxyl groups at the 2nd, 3rd and 6th positions of the glucose unit are all acylated, the acyl substitution degree is 3. Further, when all the glucose units are acylated only at the 6-position hydroxy group, the acyl substitution degree is 1. Similarly, in the case of all the hydroxyl groups of all glucoses, the acyl substitution degree is 1 when all the hydroxyl groups at the 2-position and 3-position are all acylated in each glucose unit.
That is, the degree of substitution indicates the degree of acylation, where 3 is the case where 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 acyl substitution degree of the cellulose acylate used in the present invention is preferably 1.50 to 3.00 from the viewpoint of reducing the dimensional change due to environmental humidity and having good solubility in the dope solvent. It is more preferably from 2.00 to 2.97, further preferably from 2.30 to less than 2.97, particularly preferably from 2.30 to 2.95.

The acyl group of the cellulose acylate that can be used in the present invention is not particularly limited, and may have one acyl group or may have two or more acyl groups. 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. 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, cyclohexane Examples include carbonyl, oleoyl, benzoyl, naphthylcarbonyl, cinnamoyl and the like. Among these, acetyl, propionyl, butanoyl, dodecanoyl, octadecanoyl, tert-butanoyl, oleoyl, benzoyl, naphthylcarbonyl, and cinnamoyl are preferable, and acetyl, propionyl, and butanoyl are more preferable.

Cellulose acetate using only an acetyl group as the acyl group of cellulose acylate can be suitably used in the present invention, and the acyl substitution degree of this cellulose acetate reduces the dimensional change due to environmental humidity, and is less than that of the dope solvent. In view of having good solubility, it is preferably 2.00 to 3.00, more preferably 2.20 to 3.00, still more preferably 2.30 to 3.00. It is particularly preferably 2.30 to 2.97, and most 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 and an acyl group having 3 to 4 carbon atoms, the substitution degree of the acetyl group is preferably less than 2.5, and more preferably less than 1.9. On the other hand, the substitution degree of an acyl group having 3 to 4 carbon atoms is preferably 0.1 to 1.5, more preferably 0.2 to 1.2, and 0.5 to 1. 1 is particularly preferred.
Further, mixed acid esters having fatty acid acyl groups and substituted or unsubstituted aromatic acyl groups described in paragraphs 0023 to 0038 of JP-A-2008-20896 can also be preferably used.

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 preferably has a degree of polymerization of 250 to 800, more preferably a degree of polymerization of 300 to 600. In addition, the cellulose ester or cellulose acylate used in the present invention preferably has a mass average molecular weight of 40000 to 230,000, more preferably 60000 to 230,000, and a mass average molecular weight of 75,000 to 200,000. It is particularly preferred.
The degree of polymerization can be obtained 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 (glucose unit) of cellulose ester or cellulose acylate. it can.
The mass average molecular weight in the present invention is a value measured by the gel permeation chromatograph (GPC) method under the following conditions.
[Solvent] N-Methyl-2-pyrrolidone [Device Name] TOSOH EcoSEC HLC-8320GPC
[Column] Three TOSOH SKgel Super AWM-H (6.0 mm ID × 15 cm) are connected and used.
[Column temperature] 40 ° C
[Sample concentration] 0.1% by mass
[Flow rate] 0.5 ml / min
[Calibration curve] TSK standard polystyrene made by TOSOH Mw = 2800000-1050 calibration curves with 7 samples are used.

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, 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 (acylate) the hydroxy group.
For example, by using cellulose derived from cotton linter or wood pulp as a raw material, 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. Cellulose acylate can be obtained. When an organic acid anhydride is used as an acylating agent, cellulose is generally acylated using an excess amount of 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.

In the cellulose ester layer, in addition to the cellulose ester, another resin (for example, (meth) acrylic resin or the like) can be used in combination. The content of the other resin is preferably 40% by mass or less, more preferably 30% by mass or less, still more preferably 20% by mass or less, particularly preferably 15% by mass or less, and most preferably 10% by mass or less in the cellulose ester layer. preferable.

The cellulose ester layer may contain various additives in addition to the cellulose ester and other resins. Additives that may be contained include plasticizers, organic acids, dyes, polymers other than the above polymers, retardation modifiers, ultraviolet absorbers, antioxidants, matting agents, etc., which are usually used in optical films. It is done. Regarding these additives, the description in paragraphs 0062 to 0097 of JP2012-155287A can be referred to, and the contents thereof are incorporated in the present specification.
Examples of additives other than these include peeling accelerators and polyvalent carboxylic acid derivatives. Regarding these additives, the description in paragraphs 0212 to 0219 of WO2015 / 005398 can be referred to, and the contents thereof are incorporated in the present specification.
The content of the additive (when two or more additives are contained, the total content) is not particularly limited, but is preferably 30% by mass or less, for example, 20% by mass in the cellulose ester layer. The following is more preferable.

<Layer containing cyclic polyolefin>
The cyclic polyolefin layer 12 is a layer containing 50 mass% or more of the cyclic polyolefin described later in the layer 12. In view of adhesion to the polar group-modified polyolefin layer 13 described later, the content of the cyclic polyolefin in the cyclic polyolefin layer is preferably 60% by mass or more, more preferably 70% by mass or more, and still more preferably 80% by mass or more. 85 mass% or more is particularly preferable.
As the cyclic polyolefin contains more cyclic polyolefin in the layer, the cyclic polyolefin exhibits higher adhesion to the polar group-modified polyolefin layer 13 and can impart low moisture permeability to the polarizing plate protective film. Therefore, the upper limit value of the content of the cyclic polyolefin is not particularly limited and can be 100% by mass, but for example, 99% by mass or less is preferable.

-Cyclic polyolefin-
The cyclic olefin compound forming the cyclic polyolefin is not particularly limited as long as it has a ring structure including a carbon-carbon double bond, and examples thereof include norbornene compounds, monocyclic cyclic olefin compounds other than norbornene compounds, and cyclic compounds. Examples thereof include conjugated diene compounds and vinyl alicyclic hydrocarbon compounds.
Examples of the cyclic polyolefin 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, and (3) cyclic A polymer comprising a structural unit derived from a conjugated diene compound, (4) a polymer comprising a structural unit derived from a vinyl alicyclic hydrocarbon compound, and a structural unit derived from each compound of (1) to (4) Hydrides of polymers containing 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.

The cyclic polyolefin is not particularly limited, but a polymer having a structural unit derived from a 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 the general formula, m is an integer of 0 to 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, or 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 Alternatively, (—CO) ₂ NR ¹⁵ is represented.
Here, R ¹¹ to R ¹⁵ each independently represents 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 represents a halogen atom, —OCOR ¹⁷ or —OR ¹⁷ (R ¹⁷ represents 1 to 10 carbon atoms) And p is an integer of 0 to 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 (particularly 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 a 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, 1 to 10 hydrocarbon groups, 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 ~} R ¹⁵ each independently represents a hydrogen atom, a hydrocarbon group having a carbon number of 1 ~ 20, Z represents a hydrocarbon group substituted with a hydrocarbon group or halogen, W is Si (R ¹⁶ ) _p D _(3-p) (R ¹⁶ represents a hydrocarbon group having 1 to 10 carbon atoms, D represents a halogen atom, —OCOR ¹⁷ or —OR ¹⁷ (R ¹⁷ represents 1 to 10 carbon atoms) And p is an integer of 0 to 3. n represents an integer of 0 to 10.

From the viewpoint of moisture permeability and adhesion to the polar group-modified polyolefin layer 13, the cyclic polyolefin having the structural unit represented by the general formula (A-II) or (A-III) is derived from the above norbornene compound. The structural unit is preferably contained in an amount of 90% by mass or less, more preferably 30 to 85% by mass, still more preferably 50 to 79% by mass, and further preferably 60 to 75% by mass with respect to the total mass of the cyclic polyolefin. % Content is most preferable. Here, the ratio of the structural unit derived from the norbornene compound represents an average value in the cyclic polyolefin.

Addition (co) polymers of norbornene compounds are described in JP-A-10-7732, JP-T 2002-504184, U.S. Patent Publication No. 200429129157A1, 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, a conjugated diene such as butadiene and isoprene, a non-conjugated diene such as ethylidene norbornene, acrylonitrile, acrylic acid, Specific examples 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), for example, APL8008T (Tg70 ° C.), APL6011T (Tg105). ° C), APL6013T (Tg125 ° C), APL6015T (Tg145 ° C), or the like. In addition, pellets such as TOPAS 8007, 6013, and 6015 are commercially available from Polyplastics. Furthermore, Appear 3000 is commercially available from Ferrania.

Commercially available products can be used as the norbornene compound polymer described above. 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, followed by hydrogenation. Examples of the synthesis method include JP-A-1-240517, JP-A-7-196736, JP-A-60-26024, JP-A-62-19801, JP-A-2003-159767, or JP-A-2004-309799. It is described in each gazette.

In the present invention, the cyclic polyolefin includes a crosslinked cyclic polyolefin obtained by crosslinking the above (co) polymer. Therefore, in the present invention, when simply referred to as a cyclic polyolefin, both a non-crosslinked cyclic polyolefin (sometimes called a non-crosslinked cyclic polyolefin) and a cross-linked cyclic polyolefin (sometimes called a cross-linked cyclic polyolefin) are used. It means to include.
The crosslinking form of the crosslinked cyclic polyolefin is not particularly limited, but the crosslinked cyclic polyolefin has a non-crosslinked cyclic polyolefin component and, optionally, a crosslinking component as constituent components. The cross-linking component is not uniquely determined by the cross-linking compound used for cross-linking of the non-cross-linked cyclic polyolefin, and examples thereof include a component formed by a cross-linking reaction of the following cross-linking compound with the non-cross-linked cyclic polyolefin.

-Cross-linking compounds-
Although it does not specifically limit as a crosslinking compound which bridge | crosslinks non-crosslinked cyclic polyolefin and forms crosslinked cyclic polyolefin, The compound which has an aliphatic cyclic hydrocarbon group and has an ethylenically unsaturated double bond is preferable.

(Compound having an aliphatic cyclic hydrocarbon group and having an ethylenically unsaturated double bond)
The compound having an aliphatic cyclic hydrocarbon group and having an ethylenically unsaturated double bond includes an aliphatic cyclic hydrocarbon group and a group having an ethylenically unsaturated double bond, either directly or as described later. It is a compound bound through By using this compound, the adhesion between the polar group-modified polyolefin layer and the cyclic polyolefin layer can be enhanced.

The aliphatic cyclic hydrocarbon group is not particularly limited as long as it is a group derived by removing a hydrogen atom from an aliphatic cyclic compound, preferably a group derived from an alicyclic compound having 7 or more carbon atoms. More preferably a group derived from an alicyclic compound having 10 or more carbon atoms, and still more preferably a group derived from an alicyclic compound having 12 or more carbon atoms. The upper limit of the carbon number of the alicyclic compound is preferably 40 or less, more preferably 30 or less. The aliphatic cyclic hydrocarbon group is particularly preferably a group derived from a bicyclic or tricyclic polycyclic compound. More preferably, a group derived from each compound such as a compound described in the claims of Japanese Patent Application Laid-Open No. 2006-215096, a compound described in Japanese Patent Application Laid-Open No. 2001-10999, or an adamantane derivative.
The number of rings forming the aliphatic cyclic hydrocarbon group is not particularly limited, but is usually preferably 2 to 10, more preferably 2 to 8, and still more preferably 3 to 8.

Specific examples of the aliphatic cyclic hydrocarbon group include groups derived from norbornane, tricyclodecane, tetracyclododecane, pentacyclopentadecane, adamantane, or diamantane.

As the aliphatic cyclic hydrocarbon group (including a linking group), a group represented by any one of the following general formulas (I) to (V) is preferable, and in the following general formula (I), (II) or (IV) The group represented is more preferable, and the group represented by the following general formula (I) is more preferable.

In the general formula, L ¹ and L ² each independently represent a single bond or a divalent or higher valent linking group, and a divalent or higher valent linking group is preferred. L ¹ and L ² may be the same or different, and are preferably the same.
n1 is an integer of 1 to 3, preferably 1 or 2, and more preferably 1.
* Each represents a bond portion with a group having an ethylenically unsaturated double bond. m1 is ¹ when L ¹ and L ² are each a single bond, and when L ¹ and L ² are each a linking group, the number is (the valence of the linking group minus 1).

In the general formula, L ³ and L ⁴ each independently represent a single bond or a divalent or higher linking group, and preferably a divalent or higher valent linking group. L ³ and L ⁴ may be the same or different and are preferably the same.
n2 is 1 or 2, and 1 is preferable.
* Each represents a bond portion with a group having an ethylenically unsaturated double bond. m2 is 1 when L ³ and L ⁴ are each a single bond, and is the number of (valence of the linking group minus 1) when L ³ and L ⁴ are each a linking group.

In the general formula, L ⁵ and L ⁶ each independently represent a single bond or a divalent or higher linking group, and a linking group, particularly an alkylene group is preferred. L ⁵ and L ⁶ may be the same or different and are preferably the same.
n3 is 1 or 2, and 1 is preferable.
* Each represents a bond portion with a group having an ethylenically unsaturated double bond. m3 is 1 when L ⁵ and L ⁶ are each a single bond, and m3 is the number of (valence of the linking group minus 1) when L ⁵ and L ⁶ are each a linking group.

In the general formula, L ⁷ and L ⁸ each independently represent a single bond or a divalent or higher valent linking group. L ⁹ represents a hydrogen atom, a single bond or a divalent or higher linking group. L ⁷ and L ⁸ are preferably a single bond, and L ⁹ is preferably a hydrogen atom or a single bond. L ⁷ and L ⁸ may be the same or different and are preferably the same. L ⁹ may be the same as or different from L ⁷ or L ⁸ .
* Each represents a bond portion with a group having an ethylenically unsaturated double bond. m4 is 1 when each of L ⁷ to L ⁹ is a single bond, and m4 is the number of (valence of the linking group minus 1) when each of L ⁷ to L ⁹ is a linking group. When L ⁹ is a hydrogen atom, it is 0.

In the general formula, L ¹⁰ and L ¹¹ each independently represent a single bond or a divalent or higher valent linking group, and a single bond is preferred. L ¹⁰ and L ¹¹ may be the same or different and are preferably the same.
* Each represents a bond portion with a group having an ethylenically unsaturated double bond. m5 is 1 when L ¹⁰ and L ¹¹ are each a single bond, and is the number of (valence of the linking group minus 1) when L ¹⁰ and L ¹¹ are each a linking group.

The divalent or higher linking group that can be taken as L ¹ to L ¹¹ is not particularly limited, but is preferably a divalent to pentavalent linking group, more preferably a divalent to trivalent linking group, and a divalent linking group is preferable. Further preferred.
Examples of such a linking group include a group obtained by removing a hydrogen atom of (the valence of the linking group minus 1) from a group selected from the above substituent group Z, and an amide in which the N atom may be substituted. Examples thereof include a bond, a urethane bond optionally substituted on the N atom, an ester bond, an oxycarbonyl bond, an ether bond, or a group formed by connecting two or more of these. The number of groups to be linked is not particularly limited, but is preferably 2 to 5, more preferably 2 to 3.
The divalent linking group is preferably an alkylene group having 1 to 6 carbon atoms which may be substituted, or a polyoxyalkylene group (an alkylene group having 1 to 6 carbon atoms which may be substituted and an ether bond). Are preferably an alkylene group having 1 to 6 carbon atoms which may be substituted, more preferably an alkylene group having 1 to 3 carbon atoms which is further substituted, An unsubstituted alkylene group having a number of 1 to 3 is particularly preferred. Examples of the substituent that may substitute the alkylene group include groups selected from the substituent group Z.

The group having an ethylenically unsaturated double bond is not particularly limited, but a (meth) acryloyl group, a (meth) acryloyloxy group, a vinyl group, a vinyloxycarbonyl group (—C (O) OCH═CH ₂ ), Examples thereof include a polymerizable functional group such as a styryl group or an allyl group, and among them, a (meth) acryloyloxy group and —C (O) OCH═CH ₂ are preferable.
The number of ethylenically unsaturated double bonds in the molecule of the compound having an aliphatic cyclic hydrocarbon group and a group having an ethylenically unsaturated double bond is 2 or more in terms of improving the density of crosslinking points. Preferably, there are 2 to 8, and preferably 2 to 6.
As the compound having an aliphatic cyclic hydrocarbon group and a group having an ethylenically unsaturated double bond, a compound containing two or more (meth) acryloyloxy groups in one molecule shown below is preferable. A compound containing 3 or more (meth) acryloyloxy groups in one molecule is more preferable.

The linking group for linking the aliphatic cyclic hydrocarbon group and the group having an ethylenically unsaturated double bond is not particularly limited, and is, for example, synonymous with the above-described linking groups that can be taken as L ¹ to L ¹¹ . The preferred ones are the same.

The compound is, for example, a polyol such as a diol or triol having an aliphatic cyclic hydrocarbon group, and a carboxylic acid, a carboxylic acid derivative, an epoxy derivative or an isocyanate derivative of a compound having a polymerizable functional group or the like. Alternatively, it can be synthesized by a two-step reaction.
Preferably, a compound such as (meth) acrylic acid, (meth) acryloyl chloride, (meth) acrylic anhydride or glycidyl (meth) acrylate, a compound described in International Publication No. 2012 / 00316A (Example 1, 1-bis (acryloxymethyl) ethyl isocyanate) can be synthesized by reacting with the above polyol having an aliphatic cyclic hydrocarbon group.

Hereinafter, preferred specific examples of the compound having an aliphatic cyclic hydrocarbon group and having an ethylenically unsaturated double bond are shown, but the present invention is not limited thereto.

At least one crosslinking compound can be used.
The content of the crosslinking component in the cyclic polyolefin layer is appropriately determined according to the degree of crosslinking.

The weight average molecular weight of the cyclic polyolefin 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. Particularly preferred is 50,000 to 200,000. When the molecular weight of the cyclic polyolefin is increased, the heat resistance or the mechanical strength is improved. The molecular weight of the cyclic polyolefin 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 condition-
GPC equipment: GPC equipment manufactured by Tosoh Corporation (HLC-8320GPC, Ecosec)
Column: TSK gel SuperHZM-H, TSK gel SuperHZ4000, TSK gel SuperHZ2000 combined use (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

In the present invention, the glass transition temperature (Tg) of the cyclic polyolefin is not particularly limited, but is preferably higher than the Tg of the polar group-modified polyolefin described later, and a cyclic polyolefin having a high Tg of 150 to 250 ° C. may be used. it can. The glass transition temperature of the cyclic polyolefin is more preferably in the range of 50 to 200 ° C., for example.
The crosslinked cyclic polyolefin preferably has a Tg in the above range before and after crosslinking.
Tg can be determined according to JIS K 7163, and the detailed conditions are as described in the examples.

The cyclic polyolefin layer may contain various additives in addition to the cyclic polyolefin. Examples of the additive that may be contained include various additives that may be contained in the cellulose ester layer described above. The content of the additive (when two or more additives are contained, the total content) is not particularly limited. For example, the content in the cyclic polyolefin layer is preferably 30% by mass or less, and 20% by mass. The following is more preferable.
When the cyclic polyolefin layer contains a crosslinked cyclic polyolefin, the cyclic polyolefin layer may contain a decomposition product of a crosslinking agent described later.

<Layer containing polar group-modified polyolefin>
The polar group-modified polyolefin layer 13 is a layer containing 50 mass% or more of the polar group-modified polyolefin described later in the layer 13. In terms of adhesion to the cellulose ester layer 11 and the cyclic polyolefin layer 12 described above, the content of the polar group-modified polyolefin in the polar group-modified polyolefin layer is preferably 60% by mass or more, more preferably 70% by mass or more, 80 mass% or more is still more preferable, and 85 mass% or more is especially preferable.
The more polar group-modified polyolefin is contained in the layer, the higher the adhesion to both the

layers

11 and 12 is. Therefore, the upper limit value of the content of the polar group-modified polyolefin is not particularly limited and can be 100% by mass, but is preferably 99% by mass or less, for example.
The polar group-modified polyolefin layer 13 may contain the above-described various additives in the above-described content. Moreover, when the polar group-modified polyolefin layer contains a polar group-modified crosslinked polyolefin, it may contain a decomposition product of a crosslinking agent described later.

-Polar group-modified polyolefin-
The polar group-modified polyolefin is not particularly limited as long as it is a polyolefin modified with a polar group described later, and a polyolefin satisfying the relationship of glass transition temperature described later is preferable.
The polar group-modified polyolefin is a modified product modified by introducing a polar group into the polyolefin, that is, a modified product modified by replacing a part of the functional group of the polyolefin with a polar group.
Thus, the polar group-modified polyolefin has a polar group in the molecule. The polar group-modified polyolefin preferably has a polar group as a part of a side chain, and more preferably has a side chain (pendant).

Examples of polyolefins modified with polar groups include homopolymers of α-olefins such as ethylene, propylene, butene-1,3-methylpentene-1, and 4-methylpentene-1, copolymers thereof, or And copolymers with other unsaturated monomers copolymerizable therewith.
Examples of the copolymer include ethylene copolymers such as high-density polyethylene, medium-density polyethylene, low-density polyethylene or linear low-density polyethylene, ethylene-vinyl acetate copolymer, and ethylene-ethyl acrylate copolymer. Propylene such as copolymers, ethylene-styrene copolymers, styrene-olefin copolymers such as propylene-styrene copolymers, propylene-ethylene block copolymers or random copolymers, and propylene-ethylene-diene compound copolymers Examples thereof include a copolymer, polybutene-1, and poly-4-methylpentene-1.
Of these, α-olefin homopolymers or copolymers, styrene-olefin copolymers, propylene-ethylene block copolymers or random copolymers are preferred. Propylene homopolymers, ethylene-styrene copolymers, propylene A styrene copolymer or a propylene-ethylene-styrene random copolymer is more preferable.

In the present invention, the polar group refers to an organic group that is polarized by an atom having a higher electronegativity than a hydrogen atom or a carbon atom, such as oxygen, sulfur, nitrogen, or halogen.
Specifically, an amino group (for example, amino group, methylamino group, dimethylamino group), an alkoxy group (for example, methoxy group, ethoxy group), an aryloxy group (for example, phenyloxy group), a heterocyclic oxy group ( For example, pyridinyloxy group, pyrimidinyloxy group), silyloxy group (for example, trimethylsilyloxy 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 (eg phenyloxycarbonylamino), alkyl or arylsulfonylamino group (eg methanesulfonylamino group), sulfamoyl group (eg sulfamoyl group, N-methylsulfamoyl group) N, N-dimethylsulfamoyl group), carbamoyl group (for example, carbamoyl group, N-methylcarbamoyl group, N, N-diethylcarbamoyl group), ureido group (for example, ureido group, methylureido group, phenylureido group) ), Halogen atoms (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, acid Anhydride group or hydroxide Etc. The.
Among these, a carboxy group, an acid anhydride group, a hydroxyl group, an alkoxycarbonylamino group, and an aryloxycarbonylamino group are preferable, and at least one of a carboxy group and a hydroxyl group is more preferable.

The polar group-modified polyolefin may have one or two or more of the above polar groups.
The amount of modification of the polar group in the polar group-modified polyolefin is not particularly limited, but is preferably 0.01 to 5% by mass and more preferably 0.1 to 2% by mass with respect to the total mass of the resin.

As the polar group-modified polyolefin, a carboxylic acid-modified polyolefin obtained by modifying the above-mentioned polyolefin with a carboxylic acid is preferable. In this carboxylic acid-modified polyolefin, the carboxylic acid that modifies the polyolefin contains carboxylic anhydride and does not contain the (meth) acrylic compound described later. Examples of the compound capable of introducing a carboxy group or an acid anhydride group by modifying the above-described polyolefin with a carboxylic acid-modified or carboxylic anhydride-modified include unsaturated polyvalent carboxylic acids or derivatives thereof described later. As the carboxylic acid-modified polyolefin, a carboxylic acid-modified styrene-olefin copolymer is preferable, and examples thereof include Unistor P902, Unistor P802 and Unistor H200 (all trade names) manufactured by Mitsui Chemicals.

Examples of polar group-modified polyolefins include modified polyolefin resins graft-modified with both unsaturated polyvalent carboxylic acid compounds and (meth) acrylic compounds. This modified polyolefin resin contains a carboxy group as a polar group.
The polyolefin resin used as a raw material for the modified polyolefin resin is preferably a propylene-α-olefin copolymer obtained by copolymerizing propylene as a main component with other α-olefins, such as a block copolymer and a random copolymer. Any of them may be combined. Examples of the α-olefin component copolymerized with propylene include ethylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, and 4-methyl-1-pentene. The number of carbon atoms is, for example, up to about 10. The content of the propylene component is preferably in the range of 50 to 90 mol%. When the propylene component is less than 50 mol%, the adhesion is not sufficient, and when it exceeds 90 mol%, the flexibility tends to be insufficient.
In the modified polyolefin resin, the molecular weight of the polyolefin resin as a starting material is not particularly limited, but the modified polyolefin resin after modification is preferably 15,000 to 150,000, more preferably 30000 to 120,000, and more preferably 30000 to 100,000. preferable. When the mass average molecular weight is less than 15000, the adhesion or cohesive force is weakened. On the other hand, when it is greater than 150,000, workability or solubility in a solvent tends to decrease due to an increase in viscosity.

In this modified polyolefin resin, the amount of graft modification of the unsaturated polyvalent carboxylic acid compound and the (meth) acrylic compound is 0.1 to 20 mass of the unsaturated polyvalent carboxylic acid compound relative to the total mass of the resin. %, And the (meth) acrylic compound is preferably 0.1 to 30% by mass. If the amount of graft modification is less than this range, the solubility or adhesion of the modified polyolefin resin to the solvent tends to decrease. On the other hand, if the amount of graft modification is too large, a highly reactive (meth) acrylic compound forms an ultra-high molecular weight compound, resulting in poor solubility in a solvent or formation of a homopolymer or copolymer that does not graft onto the polyolefin backbone. The amount tends to increase.

The unsaturated polyvalent carboxylic acid compound used for modification is an unsaturated polyvalent carboxylic acid, that is, a compound having an unsaturated bond and at least two carboxy groups in the molecule, or a derivative thereof. Specific examples of the unsaturated polycarboxylic acid include maleic acid, fumaric acid, tetrahydrophthalic acid, itaconic acid, citraconic acid, aconitic acid, phthalic acid, trimellitic acid, norbornene dicarboxylic acid and the like. The derivative of unsaturated polyvalent carboxylic acid is a concept including, for example, an acid anhydride, acid halide, amide, imide, ester, etc. of unsaturated polyvalent carboxylic acid as exemplified above. Among these, itaconic anhydride or maleic anhydride is preferable, and a polyolefin resin modified with a (meth) acrylic compound described later is used in view of adhesion and the like while being modified with 0.1 to 20% by mass thereof. To preferred. These unsaturated polyvalent carboxylic acid-based compounds that are modifying monomers can be used alone or in combination.

The (meth) acrylic compound is (meth) acrylic acid, that is, acrylic acid or methacrylic acid, or a derivative thereof. Derivatives of (meth) acrylic acid are methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, cyclohexyl (meth) acrylate, hydroxyethyl (meth) acrylate, isobornyl (meth) acrylate, benzyl Includes ester compounds such as (meth) acrylate, glycidyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate, and amide compounds such as acrylamide It is a concept. These (meth) acrylic compounds that are the modifying monomers can be used alone or in combination.
Among them, alkyl groups having a relatively large number of carbon atoms (for example, about 8 to 18 carbon atoms) such as octyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate, and stearyl (meth) acrylate. The (meth) acrylic acid alkyl ester having the formula: is preferred, and those containing 0.1 to 30% by mass of at least one selected from these are preferred from the viewpoint of various film properties of the resulting modified polyolefin resin.

In the above-mentioned modified polyolefin resin, monomers other than the unsaturated polyvalent carboxylic acid compound and the (meth) acrylic compound described above are used in combination as long as the properties of the present invention are not impaired. Also good. Usable monomers include copolymerizable unsaturated monomers such as styrene, cyclohexyl vinyl ether, dicyclopentadiene and the like. The amount of these monomers used preferably does not exceed the total graft modification amount of the unsaturated polyvalent carboxylic acid compound and the (meth) acrylic compound.

The above-described method for synthesizing the modified polyolefin resin can be performed according to a normal method. For example, a solution method in which a polyolefin resin is heated and dissolved in a solvent such as toluene and a modified monomer having a polar group is added, a melting method in which a modified monomer is added together with a melted polyolefin resin using a Banbury mixer, a kneader, an extruder, etc. Etc. The method for adding the modified monomer may be sequential addition or batch addition.

In the above modification reaction, a radical generator is usually used. Examples include organic peroxides such as benzoyl peroxide, di-tert-butyl peroxide, tert-butyl hydroperoxide, dicumyl peroxide, tert-butyl peroxybenzoate, methyl ethyl ketone peroxide, cumene hydroperoxide. Or azonitriles such as 2,2′-azobisisobutyronitrile and 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile).

As the modified polyolefin resin modified with an unsaturated polyvalent carboxylic acid compound and a (meth) acrylic compound, those described in JP 2002-173514 A and JP 2004-277617 A can be used. Moreover, a commercial item can be used. For example, as a commercial product, Auroren 350S, Auroren 350T and Auroren S-5106MX (all are trade names, manufactured by Nippon Paper Chemicals), Unistor P401 and Unistor P801 (all are trade names, manufactured by Mitsui Chemicals) Etc. These are all sold in the form of an organic solvent solution, and can be used as they are or after adjusting the viscosity as necessary.

In the present invention, as the polar group-modified polyolefin, Unistor P801, P802 or H200, or Aurolen 350S is preferable.

In the present invention, the polar group-modified polyolefin includes a polar group-modified crosslinked polyolefin obtained by crosslinking the above-mentioned polar group-modified polyolefin. Therefore, in the present invention, when simply referred to as a polar group-modified crosslinked polyolefin, a non-crosslinked polar group-modified polyolefin (sometimes referred to as a polar group-modified non-crosslinked polyolefin) and a crosslinked polar group-modified polyolefin (polar group-modified polyolefin). It may be referred to as a cross-linked polyolefin).
The form of crosslinking of the polar group-modified crosslinked polyolefin is not particularly limited, but the polar group-modified crosslinked polyolefin has a polar group-modified non-crosslinked polyolefin component and optionally a crosslinking component as constituent components. The crosslinking component is not uniquely determined by the crosslinking compound used for crosslinking of the polar group-modified non-crosslinked polyolefin, and examples thereof include a component obtained by crosslinking reaction of the following crosslinking compound with the polar group-modified uncrosslinked polyolefin.

-Cross-linking compounds-
The cross-linking compound that forms a polar group-modified cross-linked polyolefin by cross-linking a polar group-modified non-cross-linked polyolefin is not particularly limited. A compound that does not contain an aliphatic cyclic hydrocarbon group and has an ethylenically unsaturated double bond described below is preferable.

(Compound not containing an aliphatic cyclic hydrocarbon group and having an ethylenically unsaturated double bond)
This compound is not particularly limited as long as it does not contain an aliphatic cyclic hydrocarbon group in the molecule and has an ethylenically unsaturated double bond, and preferably contains a chain aliphatic group or an aromatic group. A compound. Examples of the aliphatic cyclic hydrocarbon group include those described above.
The group having an ethylenically unsaturated double bond and the number thereof are the same as those described above, and preferred ones are also the same.

The compound that does not contain an aliphatic cyclic hydrocarbon group and has an ethylenically unsaturated double bond is preferably a (meth) acrylate compound that does not have an aliphatic cyclic hydrocarbon group. ) Acrylic acid diester compound, (meth) acrylic acid diester compound of polyoxyalkylene glycol, (meth) acrylic acid diester compound of polyhydric alcohol, (meth) acrylic acid diester of ethylene oxide (EO) or propylene oxide (PO) adduct A compound, an epoxy (meth) acrylate compound, a urethane (meth) acrylate compound, a polyester (meth) acrylate compound, etc. can be mentioned.

Among these, ester compounds of polyhydric alcohol and (meth) acrylic acid are preferable. For example, 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol (meth) acrylate, ethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate , Pentaerythritol tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, EO modified trimethylolpropane tri (meth) acrylate, PO modified trimethylolpropane tri (meth) acrylate, EO modified Tri (meth) acrylate phosphate, trimethylolethane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate Rate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate.
Examples of the urethane (meth) acrylate compound include polyurethane polyacrylate. Examples of the polyester (meth) acrylate compound include polyester polyacrylate, caprolactone-modified tris (acryloxyethyl) isocyanurate, and the like.

A commercially available polyfunctional acrylate compound having a (meth) acryloyloxy group can be used, for example, NK ester A-TMMT (trade name, manufactured by Shin-Nakamura Chemical Co., Ltd.), KAYARAD DPHA (trade name, Nippon Kayaku Co., Ltd.).
As for the trifunctional or higher functional (meth) acrylate compounds, those described as “non-fluorinated polyfunctional monomers” in paragraphs [0114] to [0122] of JP-A-2009-98658 are used in the present invention. Can also be used.

At least one crosslinking compound can be used.
The content of the crosslinking component in the polar group-modified polyolefin layer is appropriately determined according to the degree of crosslinking and the like.

The mass average molecular weight of the polar group-modified polyolefin is not particularly limited, but is preferably 3000 to 1000000, more preferably 5000 to 800000, and still more preferably 10,000 to 500000.

In the present invention, the polar group-modified polyolefin preferably has a glass transition temperature (Tg) lower than any of the above-mentioned cellulose ester and cyclic polyolefin. Thereby, the processing characteristic of the polarizing plate formed with a polarizer can be improved, maintaining low moisture permeability and adhesiveness.
The Tg of the polar group-modified polyolefin is not particularly limited as long as the glass transition temperature is lower than both Tg of the cellulose ester and the cyclic polyolefin. It is preferably lower by ˜300 ° C., more preferably lower by 50 ° C. to 250 ° C.
Although the detailed reason is not certain about this point, the present inventors consider as follows. In the polar group-modified polyolefin used in the present invention, the polar group exhibits an interaction with a hydroxy group or a carbonyl group in the cellulose ester, while the olefin unit exhibits an interaction with the cyclic structure of the cyclic polyolefin polymer. For this reason, the adhesiveness with the layer containing a cellulose ester and the layer containing cyclic polyolefin can be improved. Furthermore, when the Tg of the polar group-modified polyolefin is in the above range, between the layer containing the cellulose ester and the layer containing the polyolefin, between the polymer contained in each layer and the polymer of the polar group-modified polyolefin. It is considered that the interaction occurs efficiently and contributes to further improvement in adhesion between each layer.
Since the above-described interaction is particularly easy to proceed in the drying process when forming a film, the effect of the present invention can be further enhanced by appropriately selecting a solvent used for forming each layer. The solvent will be described later.

In the present invention, the Tg of the polar group-modified polyolefin is not particularly limited, but preferably satisfies the above relationship. For example, Tg is preferably −150 to 100 ° C., more preferably −130 to 50 ° C. When the Tg of the polar group-modified polyolefin is within the above range, an effect of reducing the occurrence of peeling and cracking in the polarizing plate incorporating the polarizing plate protective film of the present invention can be obtained.
When the polar group-modified polyolefin is the above-mentioned crosslinked type, it is preferable to have Tg in the above range even after crosslinking. That is, the polar group-modified crosslinked polyolefin preferably has a Tg in the above range before and after crosslinking.
Tg can be determined according to JIS K 7163, and the detailed conditions are as described in the examples.

In the present invention, the polar group-modified polyolefin is preferably a carboxylic acid-modified styrene-olefin copolymer. This copolymer preferably contains 1 to 20 mol%, more preferably 2 to 10 mol% of repeating units derived from a styrene compound with respect to repeating units derived from an olefin compound. When the content of the repeating unit derived from the styrene compound relative to the repeating unit derived from the olefin compound (referred to as styrene component content) is in the range of 1 to 20 mol%, the physical strength of the polar group-modified polyolefin layer is improved. .
The styrene component content can be calculated from each content measured by ¹ H-NMR (proton nuclear magnetic resonance) of repeating units derived from a styrene compound and repeating units derived from an olefin compound.
The copolymer has an acid value defined below of 1 to 100 (mg), more preferably 5 to 60 (mg). When the acid value is from 1 to 100 (mg), the affinity for the cellulose ester is improved and good adhesion can be obtained.
The acid value is the mass (mg) of potassium hydroxide required to neutralize per gram of the carboxylic acid-modified styrene-olefin copolymer. The Japanese Industrial Standard (JIS) K 0070 (neutralization titration method) It can measure by the method according to.

<Mixed layer>
The polarizing plate protective film 10 has a mixed layer 14 between the cellulose ester layer 11 and the polar group-modified polyolefin layer 13. As described above, the mixed layer contains the cellulose ester and the polar group-modified polyolefin (in a mixed state), and has an action function of firmly bonding the cellulose ester layer and the polar group-modified polyolefin layer. The mixed layer is a layer sandwiched between two boundaries determined by a method described later.
The cellulose ester and polar group-modified polyolefin contained in the mixed layer are as described above. The mixed layer only needs to contain the cellulose ester and the polar group-modified polyolefin, and the mixed state and content ratio thereof are not uniquely determined according to the value of the above-mentioned relational expression [1]. The mixing state and the content ratio can be appropriately selected within a range not impairing the object of the present invention.
As the mixed state, for example, the state where the content ratio of the cellulose ester and the polar group-modified polyolefin is mixed at a substantially constant ratio throughout the mixed layer, the depth direction (from the polar group-modified polyolefin layer toward the cellulose ester layer). A state in which the content ratio of the cellulose ester and the polar group-modified polyolefin is changed along the direction), or a state including these. For example, the content ratio of the cellulose ester and the polar group-modified polyolefin is mixed indefinitely (randomly), or the content ratio of the polar group-modified polyolefin gradually decreases. And the cellulose ester content rate gradually increases (including the case where the polar group-modified polyolefin and cellulose ester content rates are reversed).
Among the above, the mixed state is the mixed state in which the content ratio is mixed at a substantially constant ratio throughout the mixed layer, or the content ratio of the polar group-modified polyolefin is toward at least the cellulose ester layer side of the mixed layer. It is preferable to be in a mixed state including an aspect that gradually decreases and the content ratio of the cellulose ester gradually increases. More preferably, the content ratio of the polar group-modified polyolefin gradually decreases along the depth direction, and the content ratio of the cellulose ester gradually increases (the content ratio of the polar group-modified polyolefin and the cellulose ester is reversed). It is.
The content ratio of the cellulose ester and the polar group-modified polyolefin is from 0 to less than 100 parts by mass with respect to a total of 100 parts by mass of the cellulose ester and the polar group-modified polyolefin. Is set appropriately. For example, in the above-described more preferable embodiment, the content ratio of the polar group-modified polyolefin decreases from less than 100 parts by mass to more than 0 parts by mass along the depth direction. On the other hand, the content ratio of the cellulose ester increases from over 0 parts by mass to less than 100 parts by mass along the depth direction.
As will be described later, the cellulose ester content is 0 part by mass at the interface with the polar group-modified polyolefin layer and 100 parts by mass at the interface with the cellulose ester layer. The content of the polar group-modified polyolefin is 100 parts by mass at the interface with the polar group-modified polyolefin layer and 0 part by mass at the interface with the cellulose ester layer.
The mixed layer may contain the above-described various additives in the above-described content.

As described above, the polarizing plate protective film of the present invention includes a cellulose ester layer, a mixed layer, a polar group-modified polyolefin, and a cyclic polyolefin layer. Of these layers, at least the polar group-modified polyolefin layer and the cyclic polyolefin layer preferably contain no terpene resin.
The terpene resin refers to a polymer of a terpene compound, a copolymer of a terpene compound and another polymerizable compound, and a hydrogenated product of these (co) polymers. The term “containing no terpene resin” includes, in addition to an embodiment not containing a terpene resin, an embodiment containing a terpene resin as long as the effects of the present invention are not impaired. Examples of the range in which the effects of the present invention are not impaired include a range in which the content in the solid content of the layer is less than 5% by mass.

[Physical properties of polarizing plate protective film]
The polarizing plate protective film of the present invention preferably has the following physical properties or characteristics.
(Film thickness)
The film thickness of the polarizing plate protective film of the present invention can be appropriately determined according to the use, but is preferably 5 to 100 μm, more preferably 8 to 80 μm, and still more preferably 10 to 70 μm. By making the film thickness 5 μm or more, the handling property when producing a web-like film is improved. On the other hand, when the thickness is 100 μm or less, it is easy to cope with a change in humidity and it is easy to maintain optical characteristics.
The film thickness Ts of the cellulose ester layer in the polarizing plate protective film can be appropriately determined according to the use, but is preferably 5 to 100 μm, more preferably 10 to 80 μm, and particularly preferably 15 to 60 μm. When the cellulose ester layer has a laminated structure of three or more layers, the thickness of the core layer (base layer) is preferably 3 to 70 μm, more preferably 5 to 60 μm. In the case of a three-layer structure, the thickness of skin layer A and skin layer B is preferably 0.5 to 20 μm, more preferably 0.5 to 10 μm, and still more preferably 0.5 to 3 μm. 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 the skin layers A and B are layers located outside in the laminated structure or the three-layer structure. Say.

The film thickness Tc of the cyclic polyolefin layer in the polarizing plate protective film can be appropriately determined according to the use, but is 20 μm or less in that it satisfies the requirement for thinning while satisfying a sufficiently low moisture permeability. It is preferably 1 to 15 μm, more preferably 1.5 to 10 μm.

The film thickness Tp of the polar group-modified polyolefin layer in the polarizing plate protective film is not particularly limited. For example, the total film thickness Tt with the mixed layer described later is preferably 0.2 μm or more, more preferably 0.5 μm or more, and even more preferably 0.6 μm or more. On the other hand, the total film thickness Tt is preferably 40 μm or less, and more preferably 30 μm or less. When the polar group-modified polyolefin layer has a film thickness in the above range as the total film thickness Tt with the mixed layer, the processing characteristics of the polarizing plate formed with the polarizer can be improved while maintaining low moisture permeability and adhesion.

In the mixed layer, the film thickness Tm calculated based on the oxygen atom content measured by X-ray electron spectroscopy (XPS) satisfies the relationship of the following formula (T1). If the film thickness Tm of the mixed layer is too thin, sufficient adhesion may not be obtained. On the other hand, if it is too thick, the transparency of the polarizing plate protective film may be lowered.
Formula (T1): 0.20 μm ≦ film thickness Tm ≦ 2.0 μm

-Measurement of oxygen atomic ratio-
In order to measure the thickness of the mixed layer, first, a depth direction profile (stappering time profile) of the oxygen atom ratio is obtained for the polarizing plate protective film. The profile in the depth direction for the oxygen atomic ratio can be obtained from spectral information obtained by alternately repeating the measurement of elemental composition and sputtering in the depth direction from the surface side of the cyclic polyolefin layer in the polarizing plate protective film. .
Specifically, using a Versa Probe (trade name: manufactured by Uivac-PHI), the oxygen atom ratio in the depth direction of the polarizing plate protective film was measured by the XPS (X-ray Photoelectron Spectroscopy) method under the following measurement conditions. taking measurement.
XPS measurement conditions X-ray source: Monochromatic AlKα ray analysis region: 300 × 300 μm ²
Pass Energy: 46.950eV
Light extraction angle: 45 °
Measurement elements: C1s, O1s
Sputtering conditions: Ar gas cluster ion beam gun (Ar ₂₅₀₀ ⁺ , 20 kV)

-Determination of boundaries-
Next, the two interfaces that define the mixed layer are determined from the obtained depth profile of the oxygen atomic ratio as follows.
(A) Boundary between mixed layer and cellulose ester layer: Sputtering depth at which the decrease starts when the oxygen atom ratio decreases by 5 atomic% or more from the cellulose ester layer side toward the polar group-modified polyolefin layer side (b) Mixed layer And the boundary between the polar group-modified polyolefin layer: Sputtering depth at which the decrease in the oxygen atom ratio stops (minimizes)

-Calculation of film thickness at measurement point (film thickness at measurement point)-
The film thickness of the mixed layer corresponds to the distance (depth) between the two interfaces obtained as described above, and is the average value of the film thickness of the measurement points calculated by the following equation.
(Measuring point film thickness) = [(polar group-modified polyolefin layer film thickness) / (polar group-modified olefin layer sputtering time)] × (mixed layer sputtering time)
Here, the film thickness of the polar group-modified polyolefin layer is the distance between the surface of the polar group-modified polyolefin layer and the interface (b).

-Calculation of mixed layer thickness-
The average value of the measurement point film thicknesses obtained for the three points (the center in the length direction and the vicinity of both ends) of the polarizing plate protective film as described above is defined as the film thickness Tm of the mixed layer.

The film thickness Tm of the mixed layer is preferably 0.25 to 1.5 μm, more preferably 0.50 to 1.0 μm, from the viewpoint of strong adhesion and transparency.

The polar group-modified polyolefin layer and the mixed layer preferably each have the above-mentioned film thickness (total film thickness Tt), and more preferably, in terms of adhesion, the film thickness Tm of the mixed layer and the polar group The film thickness ratio Tm / Tt of the mixed layer film thickness Tm to the total film thickness Tt with the film thickness Tp of the modified polyolefin is 0.25 to 0.65, more preferably 0.30 to 0.60. .

(width)
The width of the polarizing plate protective film is not particularly limited, but is preferably 700 to 3000 mm, more preferably 1000 to 2800 mm, and particularly preferably 1470 to 2500 mm.

(Moisture permeability)
Moisture permeability of the polarizing plate protective film of the present invention, 1600 g ^/ preferably (m 2 · 6hours) or less, more preferably 1000g ^/ (m 2 · 6hours) below, 600g ^/ (m 2 · 6hours ) Or less, more preferably 200 g / (m ² · 6hours) or less. By controlling the water vapor transmission rate of the polarizing plate protective film within the above range, the warpage of the liquid crystal cell and the black display of the image display device equipped with the polarizing plate protective film of the present invention after normal temperature, high humidity and high temperature and high humidity environment aging Display unevenness at the time can be suppressed.
The moisture permeability is a value calculated by the method described in the examples based on “moisture-proof packaging material moisture permeability test method (cup method)” of JIS Z 0208 (1976).

(Glass-transition temperature)
The polarizing plate protective film of the present invention has an excellent heat resistance because the glass transition temperature of the polar group-modified polyolefin is within the above range.

(Haze)
In the polarizing plate protective film of the present invention, the haze measured by the following method is preferably 1% or less, more preferably 0.7% or less, and particularly preferably 0.5% or less. The polarizing plate protective film of this invention can show the haze of the said range. Since the polarizing plate protective film of the present invention exhibiting such haze is excellent in transparency, it is suitable as a film member of a liquid crystal display device. Although the lower limit of haze is 0.001% or more, for example, it is not specifically limited.
The haze is JIS K7136 (2000) using a haze meter (HGM-2DP, Suga test machine) in an environment of 25 ° C. and a relative humidity of 60% for the test piece of polarizing plate protective film 40 mm × 80 mm of the present invention. Measure according to

(Moisture content)
The water content of the polarizing plate protective film (equilibrium water content) is 25 regardless of the film thickness so as not to impair the adhesiveness with a hydrophilic thermoplastic resin such as polyvinyl alcohol when used as a protective film for the polarizing plate. The moisture content at 0 ° C. and 80% relative humidity is preferably 0 to 4% by mass. The content is more preferably 0 to 2.5% by mass, and still more preferably 0 to 1.5% by mass. If the equilibrium moisture content is 4% by mass or less, the dependency of retardation due to a change in humidity does not become excessive, which is preferable from the viewpoint of suppressing display unevenness during black display of the image display device.
The moisture content is measured by measuring the 7 mm × 35 mm polarizing plate protective film of the present invention with the Karl Fischer method using a moisture meter and sample drying apparatuses “CA-03” and “VA-05” (both manufactured by Mitsubishi Chemical). . It can be calculated by dividing the amount of water (g) by the sample mass (g).

[Production method of polarizing plate protective film]
The manufacturing method of the polarizing plate protective film of this invention is demonstrated.
In the method for producing a polarizing plate protective film of the present invention, in forming a polar group-modified polyolefin layer, a forming liquid (composition) containing a polar group-modified polyolefin and a solvent satisfying the following relational expression [1] is applied on the cellulose ester layer. This is a method for forming a polar group-modified polyolefin layer. Thereby, the adhesiveness of a cellulose-ester layer and a polar group modified polyolefin layer can be made stronger. In particular, according to the above production method, a mixed layer in which a cellulose ester and a polar group-modified polyolefin are mixed can be formed between the cellulose ester layer and the polar group-modified polyolefin layer with the above-mentioned film thickness. The effect of improving the property becomes remarkable.
The thickness of the mixed layer can be appropriately set depending on the ease of dissolution or swelling of the cellulose ester by the coating solvent (hereinafter also referred to as solubility or swelling), the drying speed of the solvent, and the like.

The manufacturing method of the polarizing plate protective film of this invention is demonstrated including the manufacturing method of the cellulose-ester layer (cellulose-ester film) used for the method of applying the formation liquid for forming a polar group modified polyolefin in a cellulose-ester layer especially. To do.
The method for producing the cellulose ester film is not particularly limited, but from the viewpoint of mass production suitability (industrial production), the melt film forming method or the solution film forming method (solvent cast method) is preferable, and the additive volatilization or The solution casting method is more preferable in terms of suppressing decomposition.

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 preferable. 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)
As a casting method of the solution, a method of uniformly extruding the prepared cellulose ester solution (also referred to as a dope) for each layer from a pressure die onto a metal support, a dope once cast on a support such as a metal There are a method using a doctor blade for adjusting the film thickness with a blade, a method using a reverse roll coater for adjusting with a reverse rotating roll, etc., and a method using a pressure die is preferred. The pressure die includes a coat hanger type or 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 known methods for casting a cellulose ester solution, 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 (also called a band) whose surface is mirror-finished by surface polishing 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.

In forming the cellulose ester film, it is preferable to use a lamination casting method such as a co-casting method, a sequential casting method, or a coating method.
When manufacturing a film by the co-casting method and the sequential casting method, first, a dope for each layer is prepared.
In the co-casting method (multi-layer simultaneous casting), the dope for casting of each layer (which may be three layers or more) is then separated from a separate slit or the like on a casting support (band or drum). The dope is extruded using a caster that can be extruded at the same time, and the layers are cast simultaneously. After casting, after a suitable time, the film is peeled off from the support and dried to form a film. By using the co-casting Giesa, for example, a total of three layers of two surface 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.

In the sequential casting method, the casting dope for the first layer is first extruded from the casting giusa on the casting support, cast, dried, or dried without drying the second layer. A casting dope for casting is extruded from a casting gear and casted. Similarly, if necessary, the dope is successively cast and laminated to the third layer or more, peeled off from the support at 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 obtain a cellulose having a laminated structure. An ester film is formed.

(Stretching)
The cellulose ester film of the present invention is preferably stretched after obtaining the film by casting and drying. The stretching direction of the cellulose ester film may be either the film transport direction (MD (Machine Direction) direction) or the direction orthogonal to the transport direction (TD (Transverse Direction) 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. You can refer to the method. In the case of stretching in the TD direction, the film can be stretched by conveying the film while holding the film 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 conveyance roller to make the winding speed faster than the film peeling speed.

In the present invention, in order to suppress light leakage when the polarizing plate is viewed obliquely, a mode in which the transmission axis of the polarizer and the in-plane slow axis of the cellulose acylate film are arranged in parallel is preferable. Since the transmission axis of the roll film-shaped polarizer produced continuously is generally parallel to the width direction of the roll film, the roll film-shaped polarizer and the roll film-shaped polarizing plate of the present invention are used. In order to continuously bond the polarizing plate protective film made of the protective film, the in-plane slow axis of the roll film-shaped polarizing plate protective film needs to be parallel to the width direction of the cellulose ester film. Therefore, it is preferable to stretch more in the TD direction. The stretching process may be performed in the middle of the film forming process, or the original fabric that has been formed and wound may be stretched.

Stretch ratio of the cellulose ester film (meaning the ratio of the stretch amount to the dimension before stretching. Therefore, the stretch ratio of 1% means that the dimension of the film after stretching is 1.01 times the dimension of the film before stretching. Is preferably 1 to 100%, more preferably 5 to 60%, and particularly preferably 10 to 40%.
In particular, in the stretching in the width direction, the draw ratio is preferably 5 to 30%, more preferably 8 to 30%.
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 preferably 1 to 20% and the stretch ratio in the width direction is preferably 5 to 30%. The stretching ratio in the direction is preferably 1 to 8%, and the stretching ratio in the width direction is preferably 10 to 20%.
The stretching process may be performed in the middle of the film forming process, or the original fabric that has been formed and wound may be stretched. In the former case, stretching may be performed in a state including the residual solvent amount, but the residual solvent amount = (mass residual volatile matter / film mass after heat treatment) × 100% is in a state of 0.05 to 50%. It is preferable to stretch. It is more preferable to stretch 5 to 80% in a state where the residual solvent amount is 0.05 to 5%.

(Dry)
The method for producing a cellulose ester film preferably includes a step of drying the cellulose ester film (fluid or stretched dope).
The cellulose ester film can be dried on a metal support. The dope drying on the metal support is generally performed 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, or from the back surface of the drum or belt. And a backside liquid heat transfer method in which the temperature controlled liquid is brought into contact from the back surface opposite to the dope casting surface of the belt or drum and the drum or belt is heated by heat transfer to control the surface temperature. It is done. Among these, the back surface liquid heat transfer method is preferable. The surface temperature of the metal support before casting is not particularly limited 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 is set to 1 to 10 ° C. lower than the boiling point of the lowest boiling solvent among the solvents used. It is preferable. 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 (cellulose acylate film) from the metal support. There is no restriction | limiting in particular about the peeling method, A normal method can be used. The amount of 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 acylate film before drying, and N represents the mass when the cellulose acylate film before drying is dried at 110 ° C. for 3 hours. ]

The film thickness can be appropriately determined depending on 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, etc. so as to obtain a desired thickness.

The length of the cellulose acylate film obtained as described above is preferably wound at 100 to 10000 m per roll, more preferably 500 to 7000 m, and still more preferably 1000 to 6000 m. When winding, knurling is preferably applied to at least one end. The knurling width is preferably 3 to 50 mm, more preferably 5 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 this manner, a cellulose ester film that becomes a base material layer in the above production method can be produced.

Next, a method for forming the polar group-modified polyolefin layer on the cellulose ester layer will be described.
As described above, the polar group-modified polyolefin layer can be formed by applying a forming liquid, preferably coating and drying. Thereby, a cellulose-ester layer and a cyclic polyolefin layer can be laminated | stacked with high adhesiveness.
As the forming liquid, a composition containing a polar group-modified polyolefin, a solvent, and, if necessary, various additives in a predetermined ratio is used.

(Forming solution for forming the polar group-modified polyolefin layer)
In the present invention, the polar group-modified polyolefin layer is formed using the following forming liquid. This forming solution contains a polar group-modified polyolefin, a solvent satisfying the following relational expression [1], and, if necessary, the above-mentioned crosslinking compound, initiator, and further various additives.
If the solvent used for the forming liquid is too low in solubility or swelling in the cellulose ester, the entanglement between the cellulose ester and the polar group-modified polyolefin is not sufficient (formation of the mixed layer is insufficient), and the adhesion is further improved. It may not be possible. On the other hand, if the solubility or swellability is too high, after the solvent is removed by drying, the cellulose ester and the polar group-modified polyolefin may phase separate and the mixed layer becomes brittle. It may disappear.

From the above viewpoint, the solvent used in the forming liquid for forming the polar group-modified polyolefin layer is such that fd calculated by the following formula I satisfies the following relational expression [1].
Formula I: fd = δd / (δd + δp + δh)
Relational expression [1]: | fd _solvent −fd _cellulose | ≦ 0.10
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. Indicates. That is, fd represents the ratio of δd to the sum of δd, δp, and δh.
In the relational expression [1], fd _solvent represents the fd value of the solvent, and fd _cellulose represents the fd value of the cellulose ester.
When | fd _solvent −fd _cellulose | (rounded to the third decimal place) calculated by the relational expression [1] exceeds 0.10, swelling or dissolution of the cellulose ester by the solvent becomes insufficient, and strong adhesion May not be expressed.

The solvent contained in the forming liquid is not particularly limited as long as it satisfies the relational expression [1]. This solvent preferably satisfies the relational expression [1-A] in terms of adhesion, and more preferably satisfies the relational expression [1-B].
Relational expression [1-A]: | fd _solvent -fd _cellulose | ≦ 0.08
Relational expression [1-B]: | fd _solvent -fd _cellulose | ≦ 0.05
In the relational expression [1-A] and the relational expression [1-B], d _solvent and fd _cellulose are synonymous with the relational expression [1], respectively.

The lower limits of the relational expressions [1], [1-A] and [1-B] are all 0, but preferably 0.001.

In the present invention, fd _solvent when two or more solvents are used together (mixed solvent) is calculated by the following equation.
fd _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.
Moreover, when a cellulose-ester layer contains 2 or more types of cellulose esters, fd _{cellulose of} a cellulose ester is computed as follows.
fd _cellulose = 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 and the solvent to be used.

− Term δd corresponding to London dispersion force −
Term corresponds to the London dispersion force δd is calculated for Amorphous Polymers literature ^{"Properties of Polymers 3 rd, ELSEVIER} , (1990)" in "2) Method of Hoy (1985,1989)" column of 214-220 pages 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 214-220 pages "2) Method of Hoy (1985,1989)" described in the column 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 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 214-220 pages 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, the fd of the solvent and the cellulose ester is calculated according to Formula I, respectively. By calculating the difference between the calculated fd _solvent and fd _cellulose , it can be determined whether the solvent used satisfies the above relational expression [1].

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

As described above, the solubility parameter δt is a physical property index determined by three parameters: δd corresponding to the London dispersion force, δp corresponding to the force between dipoles, and δh corresponding to the hydrogen bond force.
It is known that compounds having a similar solubility parameter δt exhibit physical properties close to each other. However, the solubility parameter δt does not necessarily have a correlation with the structure of the compound, and there are many compounds having similar values although the structures are greatly different.
The cellulose ester used in the present invention has a glucopyranose ring portion having a small polarity and an ester portion having a high polarity and capable of forming a hydrogen bond. Accordingly, the present inventors have found that the swelling or solubility of the cellulose ester in the solvent is related to the term δp corresponding to the London dispersion force, the term δp corresponding to the dipole force, and the hydrogen bonding force corresponding to the affinity for the glucopyranose ring moiety. The sum of the terms δh corresponding to ## EQU2 ## corresponds to the affinity for the ester moiety, and it was considered important to balance the two.
Based on the above hypothesis, the inventors focused 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 force between the dipoles and the term δh corresponding to the hydrogen bond force. However, 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.
That is, as described above, since compounds having different solubility parameters have different physical properties (hydrophobicity), when these are simply laminated, the interaction at the lamination interface is insufficient, and strong adhesion cannot be obtained. There is. However, when a forming liquid for forming a polar group-modified polyolefin layer is applied on the cellulose ester layer, the polar group-modified polyolefin, the lamination interface surface, and its The cellulose ester present in the vicinity dissolves in the solvent. As a result, the interaction between the polar group-modified polyolefin and the cellulose ester is further enhanced through the solvent at the laminated interface, and in addition, a mixed layer containing the polar group-modified polyolefin and the cellulose ester is present in the vicinity of the interface between both layers. It is thought that it is formed.

Although it does not specifically limit as a solvent which can satisfy | fill said relational expression [1], 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].
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 this forming solution, the mass ratio between the polar group-modified polyolefin and the solvent is not particularly limited, but the polar group-modified polyolefin is preferably 1 to 50% by mass with respect to the total amount of the solvent. By setting it as such mass ratio, the formation liquid excellent in manufacture aptitude can be obtained.

The polar group-modified polyolefin contained in the forming liquid for forming the polar group-modified polyolefin layer is as described above, and the one having a glass transition temperature lower than any of the cellulose ester and the cyclic polyolefin is selected from them. Are preferably used.

The crosslinking compound contained in the forming liquid for forming the polar group-modified polyolefin layer is as described above.
The content of the crosslinking compound in the forming liquid for forming the polar group-modified polyolefin layer is not particularly limited, but is preferably 0 to 50% by mass with respect to the total mass of the polar group-modified uncrosslinked polyolefin and the crosslinking compound. 0 to 35 mass% is more preferable, and the range of 0 to 20 mass% is still more preferable.

The forming liquid for forming the polar group-modified polyolefin layer may contain a polymerization initiator when the polar group-modified uncrosslinked polyolefin is crosslinked with a crosslinking compound.
Examples of the polymerization initiator include a photoinitiator or a thermal initiator.
As the polymerization initiator, a thermal radical polymerization initiator can be used, but a photo radical polymerization initiator is preferable.
As radical photopolymerization initiator, acetophenone initiator, benzoin initiator, benzophenone initiator, phosphine oxide initiator, oxime initiator, ketal initiator, anthraquinone initiator, thioxanthone initiator, azo compound initiator, peroxide initiator Agents, disulfide compound initiators, lophine dimer initiators, onium salt initiators, borate salt initiators, active ester initiators, active halogen initiators, inorganic complex initiators or coumarin initiators. Specific examples, preferred embodiments, commercially available products and the like of the photopolymerization initiator are described in paragraphs [0133] to [0151] of JP-A-2009-098658, and these are also suitably used in the present invention. be able to.

Photo radical polymerization initiators include “Latest UV Curing Technology”, Technical Information Association, 1991, p. 159, and “UV curing system”, Kiyomi Kato, 1989, General Technology Center, p. Various examples are also described in 65 to 148, and these can be suitably used in the present invention.

Examples of commercially available photocleavable photoradical polymerization initiators include “Irgacure 651”, “Irgacure 184”, “Irgacure 819”, “Irgacure 907”, “manufactured by BASF (formerly Ciba Specialty Chemicals)”. "Irgacure 1870" (CGI-403 / Irgacure 184 = 7/3 mixed initiator), "Irgacure 500", "Irgacure 369", "Irgacure 1173", "Irgacure 2959", "Irgacure 4265", "Irgacure 4263", " “Irgacure 127” or “OXE01”, etc., and “Kaya Cure DETX-S”, “Kaya Cure BP-100”, “Kaya Cure BDK”, “Kaya Cure CTX”, “Kaya Cure BMS”, “Kaya Cure 2” manufactured by Nippon Kayaku Co., Ltd. -EAQ " “Kayacure ABQ”, “Kayacure CPTX”, “Kayacure EPD”, “Kayacure ITX”, “Kayacure QTX”, “Kayacure BTC”, “Kayacure MCA”, etc., and “Esacure (KIP100F, KB1, EB3, BP, X33, KTO46, KT37, KIP150, or TZT) ". A combination of these is also a preferred example.

The content of the photopolymerization initiator in the forming liquid for forming the polar group-modified polyolefin layer is set so that the above-mentioned polymerizable compound contained in the forming liquid is polymerized and the starting point does not increase excessively. For this reason, it is preferably 0.5 to 8% by mass, more preferably 1 to 5% by mass, based on the total solid content in the forming liquid.

The forming liquid for forming the polar group-modified polyolefin may contain the various additives described above as long as the effects of the present invention are not impaired.

(Application of forming solution)
The method for applying the forming liquid for forming the polar group-modified polyolefin onto the cellulose ester layer is not particularly limited, and a known method can be adopted.
For example, in addition to the melt film forming method and the solution film forming method (solvent cast method), various known coating methods on the cellulose ester layer (cellulose ester film) prepared by the above-described method may be mentioned. The coating method is preferable from the viewpoint of productivity. Examples of such coating methods include dip coating, air knife coating, curtain coating, roller coating, wire bar coating, gravure coating, or extrusion coating (die coating) (see US Pat. No. 2,681,294). ), A known method such as a micro gravure coating method is used, among which a micro gravure coating method and a die coating method are preferable. Further, the conveying speed at the time of application is not particularly limited, but it is preferable to apply at a conveying speed of 1 to 100 m / min.

(Dry)
The drying conditions of the forming solution after coating are not particularly limited, but when drying is fast (evaporation of the solvent is fast), the time for mixing the cellulose ester and the polar group-modified polyolefin is shortened, and the film thickness of the mixed layer is reduced. May be thinner. Therefore, the drying conditions take into consideration the film thickness of the mixed layer to be formed, etc. It is preferable to set appropriately. For example, the drying temperature can be selected from the range of 25 to 140 ° C., and the drying time can be selected from 30 to 1000 seconds. In particular, the drying temperature is preferably in the range of 40 to 130 ° C, and more preferably in the range of 50 to 120 ° C. The drying time is preferably in the range of 50 to 500 seconds, more preferably in the range of 60 to 300 seconds.

(Crosslinking treatment)
When the polar group-modified non-crosslinked polyolefin is crosslinked, the crosslinking treatment is performed before or after the above-described drying of the forming liquid, preferably after drying.
The crosslinking conditions are not particularly limited as long as the crosslinking reaction proceeds, and normal conditions can be appropriately selected.
For example, in the case of photopolymerization, after the solvent drying zone, a zone for curing a forming solution for forming a crosslinked polyolefin layer by ionizing radiation irradiation is passed through the web, and the forming solution is cured. For example, if the forming liquid is ultraviolet curable, it is preferable to cure the forming liquid by irradiating ultraviolet rays with an irradiation amount of 10 to 1000 mJ / cm ² with an ultraviolet lamp. In this case, the irradiation distribution in the width direction of the web is preferably 50 to 100%, more preferably 80 to 100%, including both ends with respect to the central maximum irradiation. Further, when it is necessary to purge the nitrogen gas or the like to reduce the oxygen concentration in order to promote surface hardening, the oxygen concentration is preferably 0.01% to 5%, and the distribution in the width direction is preferably 2% or less. . In the case of ultraviolet irradiation, ultraviolet rays emitted from light such as an ultrahigh pressure mercury lamp, a high pressure mercury lamp, a low pressure mercury lamp, a carbon arc, a xenon arc, or a metal halide lamp can be used. In order to accelerate the curing reaction, the temperature can be increased during curing, for example, preferably 25 to 100 ° C., more preferably 30 to 80 ° C., and most preferably 40 to 70 ° C.

Thus, a mixed layer and a polar group-modified polyolefin layer are formed in this order on the cellulose ester layer.

Next, a cyclic polyolefin layer is formed on the polar group-modified polyolefin layer.
As described above, the cyclic polyolefin layer can be formed by applying a forming liquid, preferably applying and drying, by a usual method. Thereby, a cellulose-ester layer and a cyclic polyolefin layer can be laminated | stacked with high adhesiveness.

(Forming liquid for forming the cyclic polyolefin layer)
The forming liquid for forming the cyclic polyolefin layer contains a cyclic polyolefin, a solvent, and, if necessary, the crosslinking compound, initiator, and further various additives.
In the present invention, forming the cyclic polyolefin layer using the above-described solvent having high solubility of the polar group-modified polyolefin can laminate the polar group-modified polyolefin layer and the cyclic polyolefin layer with higher adhesion. It is preferable also in that it can be performed. When the above-mentioned solvent having high solubility of the polar group-modified polyolefin layer is used, a mixed layer of the polar group-modified polyolefin and the cyclic polyolefin is formed, so that high adhesion is exhibited.
The thickness of the mixed layer can be appropriately set depending on the solubility or swelling property of the polar group-modified polyolefin by the coating solvent, the drying speed of the solvent, and the like.

The solvent contained in the forming liquid for forming the cyclic polyolefin layer is not particularly limited, and various organic solvents can be used, and a solvent in which the polar group-modified polyolefin is highly soluble as described above is preferable. As such a solvent, the said ketone solvent, acetate solvent, and a hydrocarbon solvent are mentioned preferably, for example, The same kind as the solvent contained in the formation liquid for forming a polar group modified polyolefin layer is mentioned. Other than these, chain aliphatic hydrocarbon solvents such as n-pentane, n-hexane, n-heptane, liquid paraffin, mineral spirit, cyclopentane, methylcyclohexane, dimethylcyclohexane, trimethylcyclohexane, ethylcyclohexane, Alicyclic hydrocarbon solvents such as diethylcyclohexane, decahydronaphthalene, dicycloheptane, tricyclodecane, hexahydroindene, cyclooctane and the like can also be used.

In this forming liquid, the mass ratio between the cyclic polyolefin and the solvent is not particularly limited, but the cyclic polyolefin is preferably in a proportion of 1 to 50% by mass with respect to the total amount of the solvent. By setting it as such mass ratio, the formation liquid excellent in manufacture aptitude can be obtained.

The cyclic polyolefin contained in the forming liquid for forming the cyclic polyolefin layer is as described above, and it is preferable to select and use one having a glass transition temperature higher than that of the polar group-modified polyolefin.

The crosslinking compound contained in the forming liquid for forming the cyclic polyolefin layer is as described above.
The content of the cross-linking compound in the forming liquid for forming the cyclic polyolefin layer is not particularly limited, but is preferably 0 to 50% by mass with respect to the total mass of the non-cross-linked cyclic polyolefin and the cross-linking compound, and 0 to 40%. More preferably, it is in the range of 0 to 30% by weight.

The forming liquid for forming the cyclic polyolefin layer can contain a polymerization initiator when the non-crosslinked cyclic polyolefin is crosslinked with a crosslinking compound.
Examples of the polymerization initiator include a photoinitiator or a thermal initiator.
The polymerization initiator used for crosslinking of the non-crosslinked cyclic polyolefin is preferably the same as the above-described polymerization initiator used for crosslinking of the polar group-modified non-crosslinked polyolefin.

The reason why the content of the photopolymerization initiator in the forming liquid for forming the cyclic polyolefin layer is set so that the above-described polymerizable compound contained in the forming liquid is polymerized and the starting point is not excessively increased. Therefore, the content is preferably 0.5 to 8% by mass, more preferably 1 to 5% by mass with respect to the total solid content in the forming liquid.

From the viewpoint of adhesion to the polar group-modified polyolefin layer 13, the viscosity of the forming liquid containing the cyclic polyolefin is 1 to 500 g / 10 min in the melt flow rate of the cyclic polyolefin (MFR (216 ° C., 21.2 N)). It is preferably 5 to 200 g / 10 min, more preferably 40 to 200 g / 10 min, and particularly preferably 100 to 200 g / 10 min.
MFR (216 ° C., 21.2 N) is a value measured under the conditions of 216 ° C. and 21.2 N based on ASTM D1238.

(Application and drying of forming solution)
The application method or application conditions and the drying method or drying conditions for forming the cyclic polyolefin layer are the application method or application conditions and the drying method or drying conditions for forming the polar group-modified polyolefin, respectively. The same.

(Crosslinking treatment)
When the non-crosslinked cyclic polyolefin is crosslinked, the crosslinking treatment is performed before or after the above-described drying of the forming liquid, preferably after drying.
The crosslinking conditions are not particularly limited as long as the crosslinking reaction proceeds, and normal conditions can be appropriately selected. Preferred examples of the crosslinking method and crosslinking conditions for crosslinking the non-crosslinked cyclic polyolefin include the crosslinking method and the crosslinking conditions for crosslinking the polar group-modified uncrosslinked polyolefin.

Thus, a cyclic polyolefin layer can be formed on the polar group-modified polyolefin layer, and the polarizing plate protective film of the present invention is produced.

In general, in a large screen display device, since the decrease in contrast and coloration in an oblique direction become remarkable, the polarizing plate protective film is particularly suitable for use in a large screen liquid crystal display device. When the polarizing plate protective film of the present invention is 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 and in a roll shape. A rolled up aspect is also included. The polarizing plate protective film of the latter mode is stored or transported in that state, and is used after being cut (cut) to a desired size when actually incorporated into a liquid crystal display device or bonded to a polarizer or the like. It is done. 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.

[Polarizer]
The polarizing plate of the present invention includes a polarizer and at least one polarizing plate protective film of the present invention as a protective film for the polarizer. In general, a polarizing plate in which both surfaces of a polarizer are sandwiched between polarizing plate protective films to protect both surfaces is widely used.
As a preferred example of the polarizing plate of the present invention,

polarizing plates

15A and 15B shown in FIGS. 2A and 2B, respectively, are a polarizer 16 and a polarizing plate protective film 10 provided on one surface of the polarizer 16. have.

(Polarizer)
As the polarizer, 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-treated surface of the cellulose ester layer or the cyclic polyolefin layer is formed on at least one surface of the polarizer. Can be pasted directly.

The film thickness of the polyvinyl alcohol film before stretching is not particularly limited, but is preferably 1 μm to 1 mm, particularly preferably 20 to 200 μm, from the viewpoint of film holding stability and stretching uniformity. Further, the film thickness of the stretched polyvinyl alcohol film is preferably 2 to 100 μm, and preferably 7 to 30 μm for improving light leakage. This thickness determines the thickness of the polarizer film.

(Lamination)
In this invention, the lamination | stacking aspect of the polarizing plate protective film with respect to a polarizer is not specifically limited, The aspect (The cyclic polyolefin layer 12 becomes a bonding surface) which arrange | positions the cyclic polyolefin layer 12 to the polarizer 16 side (preferably adjacent). 2A) and a mode in which the cellulose ester layer 11 is disposed (preferably adjacent) on the polarizer 16 side (the cellulose ester layer 11 becomes a bonding surface. See FIG. 2B). Especially, it is preferable from the point of durability of a polarizer that the polarizer 16 and the polarizing plate protective film 10 are laminated | stacked in the aspect which the cyclic polyolefin layer 12 and the polarizer 16 adjoin.
The polarizing plate shown in FIG. 2A and FIG. 2B has a mixed layer between the cellulose ester layer 11 and the polar group-modified polyolefin layer 13, and this mixed layer is a mixture of the polarizing plate protective film shown in FIG. Since it is the same as the layer 14, illustration of a mixed layer is abbreviate | omitted in each figure.

The production method (bonding method) of the polarizing plate of the present invention is not particularly limited, and can be produced by a general method. For example, when the cellulose ester layer 11 is used as the bonding surface, the polarization produced by subjecting the cellulose ester layer of the polarizing plate protective film of the present invention to alkali treatment (saponification treatment) and immersing and stretching the polyvinyl alcohol film in an iodine solution. A method of pasting on both sides of the child using a completely saponified polyvinyl alcohol aqueous solution or the like is mentioned. On the other hand, when the cyclic polyolefin layer 12 is used as a bonding surface, the cyclic polyolefin layer 12 of the polarizing plate protective film of the present invention is completely bonded to both sides of a polarizer prepared by immersing and stretching a polyvinyl alcohol film in an iodine solution. The method of pasting together using the fluorinated polyvinyl alcohol aqueous solution etc. is mentioned.
Instead of alkali treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed. Further, the surface of the cellulose ester layer 11 or the cyclic polyolefin layer 12 of the polarizing plate protective film is subjected to corona discharge treatment, glow discharge treatment, chromic acid treatment (wet), saponification treatment (wet), flame treatment, hot air treatment, or ozone. Alternatively, surface treatment such as ultraviolet irradiation treatment may be performed.

The polarizing plate protective film of the present invention is bonded to the polarizer so that the transmission axis of the polarizer and the slow axis of the polarizing plate protective film of the present invention are substantially parallel, orthogonal or 45 °. Is preferred. The measurement of the slow axis can be performed by various known methods, for example, using a birefringence meter (KOBRADH, manufactured by Oji Scientific Instruments).
Here, parallel, orthogonal, and 45 ° include 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.
Parallel to the transmission axis of the polarizer and the slow axis of the polarizing plate protective film means that the direction of the main refractive index nx of the polarizing plate protective film and the direction of the transmission axis of the polarizer intersect at an angle of ± 10 °. Means that. 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 polarizing plate protective film means that the direction of the main refractive index nx of the polarizing plate protective film and the direction of the transmission axis of the polarizer are in the range of 90 ° ± 10 °. It means that they intersect at an angle. 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.

Although it does not specifically limit as an adhesive agent used for bonding 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, UV curable adhesive, and the like. A particularly preferred adhesive is an aqueous solution of fully saponified polyvinyl alcohol.

The polarizing plate is composed of a polarizer and a polarizing plate protective film that protects one side or both sides of the polarizer, and at least one of the polarizing plate protective films laminated on one side or both sides of the polarizer is used as the polarizing plate of the present invention. A protective film is preferred. Therefore, deterioration of the polarizer is effectively prevented, and high polarizer durability is exhibited. Further, this polarizing plate is preferably constructed by bonding a protective film on one side and a separate film on the other side. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the liquid crystal plate. Moreover, a separate film is used in order to cover the adhesive layer bonded to a liquid crystal plate, and is used for the surface side which bonds a polarizing plate to a liquid crystal plate.

[Physical properties of polarizing plate]
The polarizing plate of the present invention preferably has the following physical properties or characteristics.
(Orthogonal transmittance CT)
In the polarizing plate of the present invention, the value of the orthogonal transmittance CT at a wavelength of 410 nm is preferably CT ≦ 2.0 (all units are%), more preferably CT ≦ 1.3, and CT ≦ More preferably, 0.6, and particularly preferably CT ≦ 0.05. The lower the orthogonal transmittance at a wavelength of 410 nm, the less light leakage near the wavelength of 410 nm. On the other hand, the higher the orthogonal transmittance at the wavelength of 410 nm, the more light leaks around the wavelength of 410 nm, and the black display on the display becomes blue. Therefore, a low orthogonal transmittance means that the polarization performance is good. From the viewpoint of polarization performance such as color reproducibility, the orthogonal transmittance at a wavelength of 410 nm is preferably low. The orthogonal transmittance can be measured using, for example, an automatic polarizing film measuring apparatus: VAP-7070 (manufactured by JASCO Corporation).

(Orthogonal transmittance change)
The polarizing plate of the present invention is excellent in durability, more specifically, in suppressing deterioration of polarizing plate performance under high temperature and high humidity conditions. As an index for evaluating durability, the amount of change in the orthogonal transmittance before and after the polarizing plate is placed under high temperature and high humidity for a predetermined period can be used. For example, the amount of change in orthogonal transmittance at a wavelength of 410 nm when left in an environment of 85 ° C. and relative humidity 85% [change amount = (orthogonal transmittance (%) after leaving) − (orthogonal transmission before leaving] Rate (%))] is preferably 0.05% or less, more preferably the change amount is 0.03% or less, still more preferably the change amount is zero or less, and the change amount is negative. It is particularly preferable that the value, that is, the orthogonal transmittance after being left is smaller than the orthogonal transmittance before being left. This means that the polarization performance has improved during standing at high temperature and high humidity. In the present invention, in addition to preventing deterioration of polarization performance under high temperature and high humidity, it is also possible to improve polarization performance.

In the present invention, the average value when the orthogonal transmittance is measured 10 times is used. Further, the amount of change in the orthogonal transmittance is obtained as the difference between the average values obtained by performing the measurement 10 times before and after leaving.

(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 degree of polarization of the polarizing plate can be determined by the following formula (I ), And the weighted average of the light source (auxiliary illuminant C) and CIE visibility (Y) is calculated according to the following formula (II).

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.

(Change in polarization degree)
The polarizing plate of the present invention is excellent in durability under severe 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 the degree of polarization when stored for 500 hours in an environment with a relative humidity of 85% is less than 1%.

(Processing characteristics)
The polarizing plate of the present invention is excellent in punching characteristics as processing characteristics such that peeling or cracking hardly occurs at the end of the cut polarizing plate 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.

(Other characteristics)
Other preferable optical characteristics and the like of the polarizing plate of the present invention are described in paragraphs 0238 to 0255 of JP-A-2007-086748, and it is preferable to satisfy these characteristics.

[Image display device]
The polarizer of the present invention is preferably used for image display device applications. Examples of such an image display device include a liquid crystal display device and an organic electroluminescence display device. Among them, it is preferably used for a liquid crystal display device.
<Liquid crystal display device>
A liquid crystal display device as an embodiment of the image display device of the present invention includes a liquid crystal cell in which liquid crystal is supported between two electrode substrates, two polarizing plates disposed on both sides thereof, and Accordingly, at least one optical compensation film is provided between the liquid crystal cell and the polarizing plate.
A preferred embodiment of the liquid crystal display device will be described.

FIG. 3 is a schematic view showing an embodiment of the liquid crystal display device. In FIG. 3, 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. 3). 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 having a light emitting diode, field emission element, or electroluminescent element as a light source is disposed on the back surface. The substrate of the liquid crystal cell generally has a thickness of 50 μm to 2 mm.
Although not shown, 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.

<Types of liquid crystal display devices>
The polarizing plate protective film of this invention can be used for the liquid crystal cell (liquid crystal display device) of various display modes. TN (Twisted Nematic), IPS (In-Plane Switching), FLC (Ferroelectric Liquid Crystal), AFLC (Anti-Ferroly Liquid Liquid Crystal), OCB (Optically QuantNW). Various display modes such as ECB (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 present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

[Reference example]
<Synthesis of cellulose acetate>
A cellulose acetate having an acetyl substitution degree of 2.87 was synthesized.
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. Moreover, it age | cure | ripened at 40 degreeC after acylation. Furthermore, the low molecular weight component of this cellulose acetate was removed by washing with acetone. In this way, cellulose acetate having an acetyl substitution degree of 2.87 and a polymerization degree of 370 was synthesized. The fd value was 0.392.

<Preparation of dope 101 for air side surface layer>
(Preparation of cellulose acylate solution 101)
Each component was put into a mixing tank with the composition shown below and dissolved by stirring to prepare a cellulose acylate solution 101.

――――――――――――――――――――――――――――――――――
Composition of Cellulose Acylate Solution 101 ――――――――――――――――――――――――――――――――――
Cellulose acetate having 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 4.0 parts by mass produced by Sigma-Aldrich (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 matting agent solution)
Each component was put into a disperser with the composition shown below and dissolved by stirring to prepare a matting agent solution.

――――――――――――――――――――――――――――――――――
Composition of matting agent solution ――――――――――――――――――――――――――――――――――
Silica particles having an average particle size of 20 nm (AEROSIL R972, manufactured by Nippon Aerosil Co., Ltd.) 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 weight The above cellulose acylate solution 101 0.9 parts by weight ―――――――――――――――――――――――――――――――― -

1.3 parts by weight of the matting agent solution and 98.7 parts by weight of the cellulose acylate solution 101 were added and mixed using an in-line mixer to prepare an air side surface layer dope 101.

<Preparation of base layer dope 102>
(Preparation of cellulose acylate solution 102)
Each component was put 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 (cellulose acylate solution) 102 ――――――――――――――――――――――――――――――――――
Cellulose acetate having 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 4.0 parts by mass produced by Sigma-Aldrich Absorbent 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 ――――――――――――――――――――――――――――

<Preparation of dope 103 for support surface layer>
1.3 parts by mass of the matting agent solution prepared in the air layer side surface dope 101 and 99.3 parts by mass of the cellulose acylate solution 101 were mixed using an in-line mixer, and the support side surface dope 103 was mixed. Was prepared.

<Film formation>
(Casting)
Using a drum casting apparatus, the above-prepared dope (base layer dope) 102 and the surface layer dopes 101 and 103 on both sides of the dope are flowed simultaneously onto a stainless steel casting support (support temperature -9 ° C.). Cast uniformly from the slot. Stripped in a state where the residual solvent amount 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 where the residual solvent amount was 3-5% by mass. The film was dried while being stretched twice. Then, it further dried by conveying between the rolls of the heat treatment apparatus, and cellulose acylate film No. 101 was obtained. The obtained cellulose acylate film No. The film thickness Ts of 101 was 57 μm (air side surface layer 3 μm, base layer 51 μm, support side surface layer 3 μm), and the width was 1480 mm.

[Example 101]
In Example 101, the polarizing plate protective film 10 shown in FIG. 1, the polarizing plate 15 </ b> A shown in FIG. 2A, and the image display device were prepared, and the adhesion, moisture permeability, polarizing plate durability, and punching were performed. Processability and display unevenness were each evaluated.

1. Preparation of polarizing plate protective film (1) Film formation of polar group-modified polyolefin layer <Preparation of forming liquid M-1 for forming polar group-modified polyolefin layer>
Each component was mixed in the composition shown below and filtered through a polypropylene filter having a pore size of 10 μm to prepare a forming liquid (composition) M-1.
In the preparation of the forming liquid M-1 and the forming liquid Ba-1, which will be described later, the glass transition temperature of the polar group-modified polyolefin is a glass of the cellulose acylate (the one having the lowest temperature among the above) and the cyclic polyolefin described later. Polar group-modified polyolefin and cyclic polyolefin were selected and used so as to be lower than the transition temperature (both shown in Table 1 or Table 2). The glass transition temperature was measured by the method described later.
Further, in the preparation of the forming liquid M-1, the solvent contained in the polar group-modified polyolefin selected so as to satisfy the relationship between the fd _cellulose value of the cellulose acetate and the glass transition temperature (in Table 1, solvent 1 and solvent 2 and And the amount of the solvent used (represented as diluent solvent 1 and diluent solvent 2 in Table 1) satisfying the above relational expression [1] and the fd _solvent value of the solvent determined in consideration of Dilution amount) was determined. Table 1 shows the calculated mass ratio of each solvent, fd _solvent , and | fd _solvent −fd _cellulose |.

――――――――――――――――――――――――――――――――――
Composition of forming liquid M-1 for forming polar group-modified polyolefin layer ―――――――――――――――――――――――――――――――――― -
Polar group-modified polyolefin: Mitsui Chemicals Unistar P802 (toluene solution with a solid content of 22% by mass) 50.0 parts by mass Methyl acetate (diluted solvent) 50.0 parts by mass ――――――――――― ――――――――――――――――――――――

<Formation of polar group-modified polyolefin layer>
In the reference example, the cellulose acylate film No. described above was used. On the surface of the cellulose acylate film that was in contact with the stainless steel casting support at the time of film formation of 101, the prepared forming liquid M-1 was prepared by a micro gravure coating method at a conveyance speed of 30 m / min. The mixture was applied and dried at 100 ° C. for 60 seconds to form the mixed layer 14 and the polar group-modified polyolefin layer 13. The total film thickness Tt of the mixed layer 14 and the polar group-modified polyolefin layer 13 was 1.0 μm.

<Preparation of Forming Liquid Ba-1 for Forming Cyclic Polyolefin Layer>
Each component was mixed with the composition shown below and filtered through a polypropylene filter having a pore size of 10 μm to prepare a forming liquid (composition) Ba-1 for forming a cyclic polyolefin layer.

――――――――――――――――――――――――――――――――――
Composition of forming solution Ba-1 for forming cyclic polyolefin layer ――――――――――――――――――――――――――――――――――
Norbornene addition copolymer: APL6011T manufactured by Mitsui Chemicals
6.0 parts by mass Fluoropolymer with the following structure 0.05 parts by mass Methylcyclohexane (solvent) 94.0 parts by mass ――――――――――――――――――――――― ――――――――――

<Formation of cyclic polyolefin layer>
On the polar group-modified polyolefin layer 13 of the cellulose acylate film on which the polar group-modified polyolefin layer 13 is formed, the prepared forming solution Ba-1 is applied by a microgravure coating method under a condition of a conveyance speed of 30 m / min. The film was dried at 100 ° C. for 60 seconds to form a cyclic polyolefin layer 12 having a film thickness Tc of 2.0 μm.

Thus, the polarizing plate protective film No. 101 was produced.

2. Preparation of polarizing plate (1) Preparation of active energy ray-curable adhesive composition Each component was mixed in the following composition and stirred at 50 ° C for 1 hour to obtain an active energy ray-curable 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: 40.0 parts by mass manufactured by Kojin Co., Ltd. Acroylmorpholine: 40.0 parts by mass manufactured by Kojin Co., Ltd. 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 ――――――――――――――――――――――――――――――――――

(2) 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.

(3) Bonding Polarizing plate protective film No. 1 produced in “1. Production of polarizing plate protective film” above. The surface of 101 on the cyclic polyolefin layer 12 side was subjected to corona treatment. The active energy ray-curable adhesive composition prepared above was applied to the surface subjected to corona treatment with an MCD coater (manufactured by Fuji Machine Co., Ltd., cell shape: honeycomb, number of gravure roll wires: 1000 / INCH, rotation speed 140% / The film was applied so as to have a film thickness of 0.5 μm.
Separately, for the cycloolefin film having a film thickness of 40 μm (Arton G7810 manufactured by JSR), after the corona treatment, the above active energy ray-curable adhesive composition was similarly applied to the surface. The film was applied to a thickness of 0.5 μm.
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.

Next, the surface of each film on which the active energy ray-curable adhesive composition was applied was bonded to one surface of the polarizer 16. At this time, the transmission axis of the polarizer 16 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 the IR heater from the both surfaces (polarizing plate protective film No. 101 or a cycloolefin type film) side of the bonded film.
Furthermore, the active energy rays shown below are irradiated from both surfaces (polarizing plate protective film No. 101 or cycloolefin film) side of the bonded film to cure the active energy ray-curable adhesive composition. I let you.
Thereafter, it was dried with hot air at 70 ° C. for 3 minutes. 101 was obtained.

(Active energy rays)
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. The illuminance of ultraviolet rays was measured using a Sola-Check system manufactured by Solatell.

3. Manufacture of Image Display Device The front and back polarizing plates and retardation plates of a VA mode liquid crystal TV (UN40JU6800F, manufactured by Samsung) were peeled off and used as a VA liquid crystal cell. Polarizing plate No. produced in “2. Production of polarizing plate” above. 101, polarizing plate No. 101. 101 was used as a bonding surface with the cycloolefin film (Arton G7810 manufactured by JSR) side of 101 as a bonding surface, and was bonded to the VA liquid crystal cell using an adhesive, and the image display device (liquid crystal display device) No. 101 was produced.
At this time, two polarizing plates No. 1 were formed on each surface of the VA liquid crystal cell. Bonding was performed so that the absorption axis of 101 was orthogonal.

[Examples 102 to 105 and Comparative Example 203]
In the production of the polarizing plate protective film of Example 101, the total film thickness Tt of the polar group-modified polyolefin layer 13 and the mixed layer, or the forming liquid M-1 determined so as to satisfy the relational expression [1] In the same manner as in the production of the polarizing plate protective film of Example 101, except that the dilution solvent was changed as shown in Table 1, Examples 102 to 105 and the polarizing plate protective film No. of Comparative Example 203 were used. . c203 was produced respectively.
Using each of the obtained polarizing plate protective films, in the same manner as the production of the polarizing plate of Example 101, the polarizing plates of Examples 102 to 105. 102 to 105 and Comparative Example 203 polarizing plate No. c203 was produced respectively.
Further, using each of the obtained polarizing plates, in the same manner as in the manufacture of the image display device of Example 101, the image display devices Nos. 102 to 105 and the image display device No. c203 was produced respectively.

[Example 106]
In the production of the polarizing plate of Example 101, the active energy ray-curable adhesive composition was used as the polarizing plate protective film No. 1 described above. Except that it was applied to the cellulose acylate film surface 101 (the side opposite to the cyclic polyolefin layer 12) and bonded so that the cyclic polyolefin layer 12 was opposite to the polarizer 16 with respect to the cellulose acylate layer 11. In the same manner as in the production of the polarizing plate of Example 101, the polarizing plate No. of Example 106 shown in FIG. 106 was produced.
Also, using the obtained polarizing plate, polarizing plate No. In the same manner as in the manufacture of the image display device of Example 101 except that the cycloolefin film side of 106 was used as the bonding surface, the image display device No. 106 was produced.

[Example 107]
1. Preparation of polarizing plate protective film (1) Film formation of polar group-modified polyolefin layer <Preparation of forming liquid M-2 for forming polar group-modified polyolefin layer>
Each component was mixed with the composition shown below and filtered through a polypropylene filter having a pore size of 10 μm to prepare a forming liquid (composition) M-2.
In the preparation of the forming liquid M-2 and the forming liquid Ba-2 described later, the glass transition temperature of the polar group-modified polyolefin is a glass composed of the cellulose acylate (the one having the lowest temperature among the above) and the cyclic polyolefin described later. Polar group-modified polyolefin and cyclic polyolefin were selected and used so as to be lower than the transition temperature (both shown in Table 1 or Table 2). The glass transition temperature was measured by the method described later.
Further, in the preparation of the forming liquid M-2, the solvents contained in the polar group-modified polyolefin selected so as to satisfy the relationship between the fd _cellulose value of the cellulose acetate and the glass transition temperature (in Table 1, solvent 1 and solvent 2 and And the amount of the solvent used (represented as diluent solvent 1 and diluent solvent 2 in Table 1) satisfying the above relational expression [1] and the fd _solvent value of the solvent determined in consideration of Dilution amount) was determined. Table 1 shows the calculated mass ratio of each solvent, fd _solvent , and | fd _solvent −fd _cellulose |.

――――――――――――――――――――――――――――――――――
Composition of forming liquid M-2 for forming polar group-modified polyolefin layer ―――――――――――――――――――――――――――――――――― -
Polar group-modified polyolefin: Mitsui Chemicals Unistar H200
100.0 parts by mass Shin-Nakamura Chemical Co., Ltd. polyethylene diacrylate A-600 8.6 parts by mass BASF Corporation Irgacure 127 (photopolymerization initiator) 1.8 parts by mass Methyl acetate (diluted solvent) 49.2 parts by mass Methyl ethyl ketone (diluent solvent) 46.7 parts by weight Methylcyclohexane (diluent solvent) 70.0 parts by mass ――――――――――――――――――――――――――― ――――――

<Formation of polar group-modified polyolefin layer>
In the reference example, the cellulose acylate film No. described above was used. When forming 101, the prepared formation liquid M-2 was applied to the surface of the cellulose acylate film that was in contact with the stainless steel casting support by the microgravure coating method, at a conveyance speed of 30 m / min. It was applied and dried at 100 ° C. for 60 seconds. Then, while purging with nitrogen gas (oxygen concentration 0.5% or less), using a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.), the formation liquid M-2 after drying was irradiated with an illuminance of 400 mW. / cm ^2, and an irradiation dose of 60 mJ / cm ^2, the polar group-modified polyolefin was cross-linked by a cross-linking compound a-600. Thus, the mixed layer 14 and the polar group-modified polyolefin layer 13 were formed. The total film thickness Tt of the mixed layer 14 and the polar group-modified polyolefin layer 13 was 1.0 μm.

(2) Film formation of cyclic polyolefin layer <Preparation of forming liquid Ba-2 for forming cyclic polyolefin layer>
Each component was mixed with the composition shown below and filtered through a polypropylene filter having a pore size of 10 μm to prepare a forming liquid (composition) Ba-2 for forming a cyclic polyolefin layer.

――――――――――――――――――――――――――――――――――
Composition of forming solution Ba-2 for forming cyclic polyolefin layer ――――――――――――――――――――――――――――――――――
Norbornene addition copolymer: APL6011T manufactured by Mitsui Chemicals
6.0 parts by weight Shinnakamura Chemical Co., Ltd. ADCP
(Tricyclodecane dimethanol diacrylate) 1.5 parts by weight Fluoropolymer having the above structure 0.05 part by weight Methylcyclohexane (solvent) 94.0 parts by weight -------- ―――――――――――――――――――

<Formation of cyclic polyolefin layer>
On the polar group-modified polyolefin layer 13 of the cellulose acylate film on which the polar group-modified polyolefin layer 13 has been formed, the prepared forming solution Ba-2 is applied by a microgravure coating method at a conveyance speed of 30 m / min. Dry at 100 ° C. for 60 seconds. Thereafter, while purging with nitrogen gas (oxygen concentration of 0.5% or less), using a 160 W / cm air-cooled metal halide lamp (manufactured by Eye Graphics Co., Ltd.), the dried forming liquid Ba-2 was given an illuminance of 400 mW / The cyclic polyolefin was cross-linked by the cross-linking compound ADCP by irradiating with ultraviolet rays of cm ² and an irradiation amount of 360 mJ / cm ² . Thus, a cyclic polyolefin layer 12 having a film thickness Tc of 2.0 μm was formed.
Thus, polarizing plate protective film No. 1 of Example 107 was used. 107 was produced.

2. Production of polarizing plate and production of image display device 107, in the same manner as in the production of the polarizing plate of Example 101, the polarizing plate No. 107 was produced.
In addition, the obtained polarizing plates No. 107, in the same manner as the manufacture of the image display apparatus of Example 101, the image display apparatus No. 107 was produced.

[Examples 108 to 114]
In producing the polarizing plate protective film of Example 107, the polarizing plate protection of Example 107 was changed except that the composition of the forming liquid M-2 and the forming liquid Ba-2 was changed as shown in Table 1 or Table 2. In the same manner as the production of the film, the polarizing plate protective film No. of Examples 108 to 111 was used. 108 to 111 were produced.
Further, in the production of the polarizing plate protective film of Example 101, except that the composition of the forming liquid Ba-2 was changed as shown in Table 2, in the same manner as the production of the polarizing plate protective film of Example 101, Polarizing plate protective films Nos. 112 to 114 were produced, respectively.

Using each of the obtained polarizing plate protective films, in the same manner as in the production of the polarizing plate of Example 101, the polarizing plates of Examples 108 to 114. 108 to 114 were produced.
Further, using the obtained polarizing plates, the image display devices of Examples 108 to 114 were respectively manufactured in the same manner as the manufacture of the image display device of Example 101.

[Comparative Example 201]
On the surface of the cellulose acylate film that was in contact with the stainless steel casting support at the time of forming the cellulose acylate film in Example 1, the forming liquid Ba-1 was transferred by a microgravure coating method at a conveyance speed of 30 m / The film was applied under the conditions of minutes and dried at 100 ° C. for 60 seconds to form a cyclic polyolefin layer having a thickness of 2.0 μm. In this way, the polarizing plate protective film No. c201 was produced.
The obtained polarizing plate protective film No. In the same manner as the production of the polarizing plate of Example 101, the polarizing plate No. c201 was produced.
In addition, the obtained polarizing plate No. c201, in the same manner as in the manufacture of the image display apparatus of Example 101, the image display apparatus No. c201 was produced.

[Comparative Example 202]
Using the cellulose acylate film prepared in Example 1 as a polarizing plate protective film, the polarizing plate No. of Comparative Example 202 was prepared in the same manner as the polarizing plate of Example 101. c202 was produced. However, the surface of the cellulose acylate film was used as a bonding surface with the polarizer 16.
Further, this polarizing plate No. c202, the image display device No. of Comparative Example 201 is manufactured in the same manner as in the manufacture of the image display device of Example 101. c202 was produced.

[Comparative Example 204]
1. Preparation of polarizing plate protective film <Preparation of aqueous dispersion of AN42115C>
100 parts by mass of an ethylene-methacrylic acid copolymer (Mitsui / DuPont Polychemical Co., Ltd., Nucleel AN42115C), 233 parts by mass of n-propanol, 27 parts by mass of 2-dimethylaminoethanol, and 307 parts by mass of distilled water were mixed. The mixture was stirred at a rotation speed of 300 rpm for 10 minutes. Furthermore, after heating up to 150 degreeC, it stirred for 120 minutes at 150 degreeC. Next, after cooling the temperature in the system to 40 ° C., 330 parts by mass of isopropanol was added to obtain an aqueous dispersion having a solid content concentration of 10% by mass.
<Formation of polar group-modified polyolefin layer and production of polarizing plate protective film>
A polar group-modified polyolefin layer was formed in the same manner as in Example 101 except that the aqueous dispersion of the ethylene-methacrylic acid copolymer was used as a forming liquid for forming the polar group-modified polyolefin layer in Example 101. The polarizing plate protective film No. c204 was produced.

2. Production of polarizing plate and production of image display device In the same manner as in the production of the polarizing plate of Example 101, the polarizing plate No. c204 was produced.
In addition, the obtained polarizing plate No. c204, in the same manner as in the manufacture of the image display apparatus of Example 101, the image display apparatus No. c204 was produced.

Table 2 shows the results of measuring or identifying the physical properties or characteristics of cellulose acylate, cyclic polyolefin and polar group-modified polyolefin used in Examples and Comparative Examples.
1. Measurement of Glass Transition Temperature With respect to cellulose acylate, cyclic polyolefin and polar group-modified polyolefin used in Examples and Comparative Examples, glass transition temperature was measured by the following method and conditions.
Using a differential scanning calorimeter (X-DSC7000, manufactured by IT Measurement Control Co., Ltd.), 20 mg of a sample was placed in a measurement pan, and this was measured in a nitrogen stream with the following temperature history to measure the glass transition temperature.

(Temperature history of cellulose acylate film)
The temperature was raised from 25 ° C. to 180 ° C. at a rate of 20 ° C./min, and then cooled to 25 ° C. at −20 ° C./min. Thereafter, the temperature is raised again from 25 ° C. to 200 ° C. at a rate of 20 ° C./min, and the average value of the temperature at which the baseline starts to deviate from the low temperature side and the temperature at which the baseline returns again is defined as the glass transition temperature Tg. .
(Temperature history of cyclic polyolefin)
The temperature was raised from 25 ° C. to 180 ° C. at a rate of 20 ° C./min, and then cooled to 25 ° C. at −20 ° C./min. Thereafter, the temperature was raised again from 25 ° C. to 180 ° C. at a rate of 20 ° C./min, and the average value of the temperature at which the baseline starts to deviate from the low temperature side and the temperature at which the baseline returns again was defined as the glass transition temperature Tg. .
(Temperature history of polar group-modified polyolefin)
The sample was cooled from 25 ° C. to −150 ° C. at a rate of −20 ° C./min, held at −150 ° C. for 2 minutes, and then heated to 200 ° C. at a rate of 20 ° C./min. Further, it was cooled to −150 ° C. at −20 ° C./min. Thereafter, the temperature was raised again from −150 ° C. to 200 ° C., and the average value of the temperature at which the baseline began to deviate from the low temperature side and the temperature at which the baseline returned to the baseline again was defined as the glass transition temperature Tg.
When the polar group-modified polyolefin contains a solvent, it was held at 140 ° C. for 3 hours to evaporate the solvent, and then subjected to the above measurement.

2. Identification of polar group-modified polyolefin, and measurement of styrene component content and acid value Unistol P802 used in Example 101 and the like was obtained by identifying and measuring polar groups and their modified amounts by the following method. This was a maleic anhydride-modified styrene-olefin copolymer having a modification amount of 0.1 to 1.0 mol%.
- Measuring method -
The peak intensity derived from maleic anhydride was quantified by pyrolysis GC / MS (gas chromatograph mass spectrometry) at 600 ° C.

Further, regarding the maleic anhydride-modified styrene-olefin copolymer contained in Unistor P802, the styrene component content and the acid value were measured based on the above-described method.

Unistar H200 used in Example 107 and the like is a methylcyclohexane / methyl ethyl ketone = 60/40 (mass ratio) solution having a solid content of 20% by mass. The polymer to be contained was a maleic anhydride-modified styrene-ethylene copolymer having a maleic anhydride modification amount of 0.1 to 1.0 mol% when the polar group and its modification amount were identified and measured by the following method. there were.
Based on the above-mentioned method, the styrene component content and the acid value of the maleic anhydride-modified styrene-ethylene copolymer contained in UNISTOL H200 were measured.

Aurorene 350S used in Examples 110 and 111 was a carboxylic acid-modified ethylene-propylene copolymer having an acid value of 38.

3. Identification of cyclic polyolefin APL6011T, APL6013T, and APL3015T used in the Examples as cyclic polyolefins all contained a copolymer of ethylene and a norbornene compound.
Further, TOPAS 6013 used in Example 114 is a cycloolefin copolymer (manufactured by Topas Advanced Polymers GmbH) obtained by copolymerizing a norbornene compound and ethylene with a metallocene catalyst.

[Measurement of film thickness of mixed layer]
About the polarizing plate protective film produced by the Example and the comparative example, the film thickness Tm of the mixed layer was measured by the above-mentioned method. Table 2 shows the results of calculating the film thickness ratio Tm / Tt.
Depth direction profiles for the oxygen atom ratios obtained by XPS of the polarizing plate protective films prepared in Examples 101 and 109 are shown in FIGS. 4 and 5, respectively.

[Mixed state and mixing ratio of mixed layer]
The mixed state and mixing ratio of the mixed layer were confirmed by the depth direction profile of the oxygen atomic ratio obtained in the above [Measurement of film thickness of mixed layer].
For example, as shown in FIG. 4 and FIG. 5, the mixed layers of the polarizing plate protective films of Examples 101 to 114 all have the content of the polar group-modified polyolefin decreased along the depth direction. It was confirmed that the content ratio was increased (the content ratio of the polar group-modified polyolefin and the cellulose ester was reversed). In addition, the content ratios of cellulose acylate and polar group-modified polyolefin are each from 0 to 100 parts by mass in the depth direction with respect to a total of 100 parts by mass of cellulose acylate and polar group-modified polyolefin. It increased to less than or decreased from less than 100 parts by mass to more than 0 parts by mass.

The polarizing plate protective film, the polarizing plate, and the image display device produced or manufactured as described above were evaluated as follows. The results are shown in Table 2.

First, the moisture permeability and adhesiveness were evaluated about the produced polarizing plate protective film.
<Moisture permeability>
The moisture permeability of the produced polarizing plate protective film 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 was cut into 60 mm × 60 mm, and the mass (g / 6hours) of water vapor passing through the polarizing plate protective film in 6 hours in an atmosphere at a temperature of 85 ° C. and a relative humidity of 85% was measured. Then, it was converted (g / (m ² · 6 hours)) per 1 m ² of the polarizing plate protective film.
In this test, the mass of water vapor was calculated from the mass change of anhydrous calcium chloride as a hygroscopic agent.

<Adhesion>
The produced polarizing plate protective film was conditioned for 2 hours under the conditions of a temperature of 25 ° C. and a relative humidity of 60%. A total of 100 square squares were carved on the surface on the side having the cyclic polyolefin layer with a cutter knife, with 11 vertical and 11 horizontal cuts in a grid pattern at 1 mm intervals. A polyester adhesive tape (No. 31B) manufactured by Nitto Denko Co., Ltd. was attached to the 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 test was performed three times and the average was taken.
In this test, evaluation A or B is a pass level.
A: No peeling was observed at 100 mm.
B: Peeling of 1 to 10 mm was observed at 100 mm.
C: Peeling of 11 to 30 mm was observed at 100 mm.
D: Peeling of 31 mm or more was observed at 100 mm.
E: Peeling was recognized when the cut was made with a cutter knife.

Next, the produced polarizing plate was evaluated for punching characteristics and polarizing plate durability.
<Processing characteristics: Punching characteristics (appropriate) of polarizing plate>
The produced polarizing plate was allowed to stand in an atmosphere of 80 ° C. for 24 hours and then conditioned for 24 hours under the conditions of a temperature of 25 ° C. and a relative humidity of 10%. Four samples having a size of 4 × 4 cm were punched out from the humidity-controlled polarizing plate by a puncher equipped with a Thomson blade at an angle of 45 degrees with respect to the absorption axis of the polarizer. For the punched 4 × 4 cm polarizing plate sample (4 sheets), the peeling width of each side (depth: the shortest distance from the edge of each side to the tip of the peeled portion in the direction toward the inside of the sample) And evaluated as follows.
In this test, evaluation A or B is a pass level.
In the measured peeling width, the maximum peeling width is A: less than 0.4 mm B: 0.4 mm or more and less than 0.8 mm C: 0.8 mm or more and less than 1.2 mm D: 1.2 mm or more

<Polarizing plate durability>
About each polarizing plate, 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 amount of change in polarization degree was evaluated according to the following criteria. In this test, evaluation A, B, or C is an acceptable level.

Polarization degree change (%) = [Polarization degree before storage (%) − Polarization degree after storage (%)]

A: Polarization degree change amount is less than 0.05% B: Polarization degree change amount is 0.05% or more and less than 0.1% C: Polarization degree change amount is 0.1 or more and less than 1% D: Polarization degree change amount 1% or more

Finally, display unevenness (water contact unevenness) was evaluated for the manufactured image display device.
<Display unevenness>
In the state where each manufactured image display device was laid down sideways, a 2 cm × 2 cm Bencot (manufactured by Asahi Kasei Co., Ltd.) was placed on the center of the surface of the viewing side polarizing plate. Using a micropipette, 150 μL of pure water was dropped onto the becot, and the polarizing plate was immediately covered with Saran Wrap (registered trademark, manufactured by Asahi Kasei Home Products), and the periphery was attached and sealed with Kapton tape (manufactured by Nitto Denko). . This state was left for 48 hours. Thereafter, Saran Wrap (registered trademark) and Bencott were removed, the water on the polarizing plate surface was wiped off, the image display device was lit for 30 minutes, and the panel was visually observed from the front when displaying black in a dark room. .
Furthermore, when black was displayed in a dark room, a digital camera (FinePix S200EXR) was photographed from the front (shutter speed 3 seconds), and the photographed image was analyzed using image analysis software ImageJ, and evaluated as follows.
In this test, evaluation A, B, or C is an acceptable level.
A: Unevenness is not visually recognized, and the difference between the water contact portion and the surrounding brightness (gray value) is less than 3. B: Unevenness is slightly visually recognized, and the brightness of the water contact portion and the surrounding area is small. (Gray Value) difference is 3 or more and less than 8 C: Unevenness is visually recognized, and the difference between the water contact portion and the surrounding brightness (gray value) is 8 or more and less than 15 D: Unevenness is visually recognized. In addition, the difference between the water contact portion and the surrounding luminance (gray value) is 15 or more (luminance (gray value) = 0.299 red + 0.587 green + 0.114 blue)

In Table 1, “-” indicates that the component of the forming liquid is not contained, and that the adhesion test is not performed.

From the results of Tables 1 and 2, the following was found.
Polarizing plate protective film No. having no polar group-modified polyolefin layer c201 had insufficient adhesion, and the punching characteristics of the polarizing plate were inferior. Moreover, polarizing plate protective film No. which consists only of a cellulose acylate layer. c202 was inferior in moisture permeability, and therefore inferior in polarizing plate durability and display unevenness. Furthermore, polarizing plate protective film No. 1 in which a polar group-modified polyolefin layer was formed using a forming solution prepared using a solvent that did not satisfy the above relational expression [1]. Even if c203 and c204 had a mixed layer, the film thickness was too thin and did not show sufficient adhesiveness.

In contrast, the polarizing plate protective film No. 1 of the present invention. All of 101 to 114 had low moisture permeability and excellent adhesion. In this way, the polarizing plate protective film No. 1 in which the polar group-modified polyolefin layer was formed using a forming liquid containing a solvent satisfying the above specific relational expression [1]. Each of 101 to 114 has a mixed layer having a predetermined film thickness containing a cellulose ester and a polar group-modified polyolefin between the cellulose ester layer and the polar group-modified polyolefin layer. It was shown that the adhesiveness with the group-modified polyolefin layer becomes strong.
Moreover, polarizing plate No. using the polarizing plate protective film of this invention. Nos. 101 to 114 were those in which a decrease in the degree of polarization was suppressed even when stored in a high temperature and high humidity environment, and peeling during punching was less likely to occur. In particular, the cyclic polyolefin layer was disposed on the side closer to the polarizer with respect to the cellulose acylate layer (the cyclic polyolefin layer was disposed adjacent to the polarizer via the adhesive layer). No. 101 is a polarizing plate No. 101 having a cyclic polyolefin layer disposed on the side farther from the polarizer (viewer side) than the cellulose acylate layer. Compared to 106, the polarizing plate was excellent in deterioration prevention property when stored in a high-temperature and high-humidity environment, and showed higher polarizer durability.
Furthermore, the image display device No. using the polarizing plate provided with the polarizing plate protective film of the present invention. Nos. 101 to 114 exhibited excellent durability with less display unevenness even when stored in a high temperature and high humidity environment.

While this invention has been described in conjunction with its embodiments, we do not intend to limit our invention in any detail of the description unless otherwise specified and are contrary to the spirit and scope of the invention as set forth in the appended claims. I think it should be interpreted widely.

This application claims priority based on Japanese Patent Application No. 2015-256469 filed in Japan on December 28, 2015 and Japanese Patent Application No. 2016-247551 filed in Japan on December 21, 2016 Which are hereby incorporated by reference herein as part of their description.

DESCRIPTION OF SYMBOLS 10 Polarizing plate protective film 11 Layer containing cellulose ester 12 Layer containing cyclic polyolefin 13 Polar group modified polyolefin layer 14

Mixed layer

15A, 15B Polarizing plate 16 Polarizer 20 Liquid crystal display device 21 1st (upper side) polarizing plate 22 1st 1 Direction of polarizing plate absorption axis 23 First (upper liquid crystal cell) electrode substrate 24 Liquid crystal layer 25 Second (lower liquid crystal cell) electrode substrate 26 Second (lower side) polarizing plate 27 Direction of second polarizing plate absorption axis

Claims

A polarizing plate protective film having a layer containing a cellulose ester, a layer containing a cyclic polyolefin, and a layer containing a polar group-modified polyolefin between the layer containing the cellulose ester and the layer containing the cyclic polyolefin Because
Between the layer containing the cellulose ester and the layer containing the polar group-modified polyolefin, based on the oxygen atom content measured by X-ray electron spectroscopy, containing the cellulose ester and the polar group-modified polyolefin. The polarizing plate protective film which has a mixed layer in which the film thickness computed in (2) satisfy | fills the relationship of a following formula (T1).
Formula (T1): 0.20 μm ≦ film thickness ≦ 2.0 μm
The polarizing plate protective film according to claim 1, wherein the polar group contains at least one of a carboxy group and a hydroxyl group.
The polar group-modified polyolefin is a carboxylic acid-modified styrene-olefin copolymer, and the carboxylic acid-modified styrene-olefin copolymer has a repeating unit derived from a styrene compound to 1 repeating unit derived from an olefin compound. 3. The polarizing plate protective film according to claim 1, wherein the polarizing plate protective film is contained in an amount of not less than 20% by mole and not more than 20% by mole, and has an acid value defined below of 1 to 100.
Acid value: Mass of potassium hydroxide required to neutralize per gram of carboxylic acid-modified styrene-olefin copolymer (mg)
The polarizing plate protective film according to any one of claims 1 to 3, wherein the polar group-modified polyolefin has a glass transition temperature lower than that of the cellulose ester and the cyclic polyolefin.
A polarizing plate protective film having a layer containing a cellulose ester, a layer containing a cyclic polyolefin, and a layer containing a polar group-modified polyolefin between the layer containing the cellulose ester and the layer containing the cyclic polyolefin A method of manufacturing
Polarizing plate protection for forming a layer containing the polar group-modified polyolefin by applying a forming liquid containing a polar group-modified polyolefin and a solvent satisfying the following relational expression [1] on the cellulose ester-containing layer A method for producing a film.
Relational expression [1]: | fd solvent -fd cellulose | ≦ 0.10
In the relational expression [1], fd solvent represents the fd value of the solvent, and fd cellulose represents the fd value of the cellulose ester.
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. Indicates.
A method for producing a polarizing plate protective film according to any one of claims 1 to 4,
Polarizing plate protection for forming a layer containing the polar group-modified polyolefin by applying a forming liquid containing a polar group-modified polyolefin and a solvent satisfying the following relational expression [1] on the cellulose ester-containing layer A method for producing a film.
Relational expression [1]: | fd solvent -fd cellulose | ≦ 0.10
In the relational expression [1], fd solvent represents the fd value of the solvent, and fd cellulose represents the fd value of the cellulose ester.
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. Indicates.
A polarizing plate comprising the polarizing plate protective film according to any one of claims 1 to 4 and a polarizer.
The polarizing plate according to claim 7, wherein a layer containing the cyclic polyolefin of the polarizing plate protective film is disposed on the polarizer side.
An image display device comprising the polarizing plate according to claim 7 or 8.