WO2017145469A1 - Laminate, polarizing plate and image display device - Google Patents

Abstract

A laminate which comprises a cellulose ester resin layer and a layer that is provided directly on the cellulose ester resin layer and contains a polymer having a repeating unit represented by general formula (1), and wherein the polymer has a glass transition temperature of 50°C or higher; a polarizing plate which uses this laminate; and an image display device which uses this polarizing plate. In general formula (1), R^a represents a hydrogen atom, an alkyl group or an alkoxycarbonyl group; each of R^b and R^c represents a hydrogen atom, an alkyl group, an aryl group or an alkoxycarbonyl group; and R² represents an alkyl group, a cycloalkyl group or an aryl group.

Description

Laminated body, polarizing plate, and image display device

The present invention relates to a laminate, a polarizing plate using the laminate, and an image display device using the polarizing plate.

Image display devices represented by electroluminescence displays (ELD), liquid crystal display devices (LCD), and the like are increasingly demanded for thinning. In addition, the usage environment of image display devices has been diversified, including outdoor applications, and image display devices have the ability to stably maintain good image quality even in harsh environments (high durability). Is now required.
The decrease in image quality in the image display device is partly caused by water entering the polarizing plate and degrading the polarizer. The polarizer is protected by laminating a protective film (optical film) on the surface, and the protective film is also required to be thin. When the protective film is thinned, water is more likely to come into contact with the polarizer, and the image quality is likely to deteriorate. Further, such a decrease in image quality becomes more apparent when used under harsh environments such as outdoor applications.
Moreover, in order to obtain a practical protective film, it is also important to suppress fluctuations with time of optical characteristics of the protective film as much as possible. However, in general, the protective film tends to deteriorate in optical characteristics when used in the harsh environment described above (particularly in a high temperature environment). Examples of such deterioration of optical characteristics include an increase in haze value and film coloring.

As the protective film, cellulose ester resins, acrylic resins, and the like are widely used from the viewpoints of versatility and processability. It is also known to form a protective film using a blend resin in which a cellulose ester and an acrylic resin are mixed in order to obtain a desired protective film exhibiting desired optical properties and moisture permeability (for example, Patent Documents 1 and 2).

JP 2010-243935 A JP 2013-24963 A

As a result of studying the conventional protective films including the films described in Patent Documents 1 and 2, the present inventors have found that these protective films are particularly suitable for polarizers when they are highly thinned to the above-mentioned required levels. It has become clear that it is difficult to adequately address the problem of degradation.
In addition, when these protective films are stored in a high temperature environment, the haze value tends to increase, and it is difficult to maintain good display performance when these protective films are incorporated into an image display device. It has also become clear.
The present invention is a laminate comprising a cellulose ester resin layer, which has excellent interlayer adhesion, and suppresses deterioration of the polarizer over time even when it is thinned and used as a protective film for a polarizer. In addition, a laminate that suppresses the increase in haze value over time even in a high-temperature environment and can maintain good display performance for a long time when incorporated in an image display device, and uses this laminate. It is an object of the present invention to provide a polarizing plate and an image display device using the polarizing plate.

As a result of intensive studies in view of the above problems, the present inventors directly provided a layer containing a polymer having a repeating unit having a specific structure and having a glass transition temperature equal to or higher than a specific temperature on the cellulose ester resin layer. The laminate is excellent in adhesion between layers, can suppress the increase in haze value over time even in a high temperature environment, and when used as a protective film for a polarizer, It was found that deterioration can be suppressed.
The present invention has been further studied based on these findings and has been completed.

The above-described problems of the present invention have been solved by the following means.
[1]
It has a cellulose ester resin layer and a layer containing a polymer having a repeating unit represented by the following general formula (1) provided directly on the cellulose ester resin layer, and the glass transition temperature of this polymer is 50 ° C. That is the laminate.

In General Formula (1), R ^a represents a hydrogen atom, an alkyl group, or an alkoxycarbonyl group.
R ^b and R ^c represent a hydrogen atom, an alkyl group, an aryl group or an alkoxycarbonyl group.
R ² represents an alkyl group, a cycloalkyl group or an aryl group.
L ¹ represents a divalent linking group formed by combining two or more divalent groups selected from an alkylene group, an arylene group, —C (═O) —, —O—, and —NR ³ —. However, L ¹ includes a group represented by —C (═O) NR ³ —.
R ³ represents a hydrogen atom or a substituent.
[2]
The laminate according to [1], wherein the repeating unit represented by the general formula (1) is a repeating unit represented by the following general formula (2) or (3).

In general formula (2), R ^1a represents a hydrogen atom or methyl.
R ² has the same meaning as ^{R 2} in the general formula (1).
L ² represents an alkylene group, an alkyleneoxy group or a polyalkyleneoxy group.
A represents —C (═O) NR ³ — or —NR ³ —C (═O) —NR ³ —. R ³ has the same meaning as ^{R 3} in the general formula (1).

In the general formula ^{(3), R 1a} and ^{R 2} are the same meanings as ^{R 1a} and ^{R 2} in the general formula (2).
R ^3a represents a hydrogen atom or an alkyl group.
[3]
The laminate according to [2], wherein the repeating unit represented by the general formula (3) is a repeating unit represented by the following general formula (4).

In the general formula ^{(4), R 1a} and ^{R 2} are the same meanings as ^{R 1a} and ^{R 2} in the general formula (3).
[4]
The polymer having a repeating unit represented by the general formula (1) has a repeating unit represented by the general formula (1) and a repeating unit represented by the following general formula (5). ] To [3].

In General Formula (5), R ⁴ and R ⁵ represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxycarbonyl group.
R ⁶ represents a hydrogen atom or an alkyl group.
L ³ is a single bond, a divalent group selected from an alkylene group, an arylene group, —C (═O) —, —O— and —N (R ^3A ) —, or two of these groups A divalent linking group formed by combining the above is shown.
R ^3A represents a hydrogen atom or a substituent.
[5]
The laminate according to any one of [1] to [4], wherein the content of the polymer having the repeating unit represented by the general formula (1) is 1 to 30% by mass in the laminate.
[6]
[1] A polarizing plate comprising the laminate according to any one of [5] and a polarizer.
[7]
The image display apparatus which has a polarizing plate as described in [6].

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

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

In this specification, about the display of a compound, it uses in the meaning containing its salt and its ion besides the compound itself. In addition, it means that a part of the structure is changed as long as the desired effect is achieved.
Examples of the salt of the compound include, for example, an acid addition salt of the compound formed with the compound and an inorganic acid or an organic acid, or a base addition salt of the compound formed with the compound and an inorganic base or an organic base. Is mentioned. In addition, examples of the ion of the compound include an ion including a skeleton of the compound formed by dissociating the salt of the above-described compound.
In the present specification, a substituent that does not specify substitution or non-substitution (the same applies to a linking group) means that the group may have an arbitrary substituent as long as a desired effect is achieved. . This is also the same for compounds that do not specify substitution or non-substitution.
In the present specification, the term “substituent” includes groups selected from the following substituent group T unless otherwise specified. In addition, when only a substituent having a specific range is described (for example, when only described as “alkyl group”), a corresponding group of the following substituent group T (in the above case, an alkyl group) The preferred range in FIG.
In the present specification, when the number of carbon atoms of a certain group is defined, this number of carbons means the total number of carbon atoms in the group. That is, when this group is a form further having a substituent, it means the total number of carbon atoms including this substituent.

Substituent group T:
An alkyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12 carbon atoms, particularly preferably 1 to 8 carbon atoms such as a methyl group, an ethyl group, an isopropyl group, a tert-butyl group, an n-octyl group, n-decyl group, n-hexadecyl group, etc.), cycloalkyl group (preferably having 3 to 20, more preferably 3 to 12, particularly preferably 3 to 8 carbon atoms, cyclopropyl group) , A cyclopentyl group, a cyclohexyl group, etc.), an alkenyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferably 2 to 8 carbon atoms such as vinyl group, allyl group, 2- Butenyl group, 3-pentenyl group, etc.), alkynyl group (preferably having 2 to 20 carbon atoms, more preferably 2 to 12 carbon atoms, particularly preferred) 2-8, for example, propargyl group, 3-pentynyl group, etc.), aryl group (preferably 6-30 carbon atoms, more preferably 6-20, particularly preferably 6-12, For example, a phenyl group, a biphenyl group, a naphthyl group, etc.), an amino group (preferably having a carbon number of 0 to 20, more preferably 0 to 10, particularly preferably 0 to 6, such as an amino group, methylamino Group, dimethylamino group, diethylamino group, dibenzylamino group, etc.), alkoxy group (preferably having 1 to 20 carbon atoms, more preferably 1 to 12, particularly preferably 1 to 8, such as methoxy Group, ethoxy group, butoxy group, etc.), aryloxy group (preferably having 6 to 20 carbon atoms, more preferably 6 to 16 carbon atoms). Particularly preferred is 6 to 12, for example, phenyloxy group, 2-naphthyloxy group, etc.), acyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 1 carbon atoms). 12 such as an acetyl group, a benzoyl group, a formyl group, and a pivaloyl group), an alkoxycarbonyl group (preferably having 2 to 20, more preferably 2 to 16, and particularly preferably 2 to 12 carbon atoms). For example, methoxycarbonyl group, ethoxycarbonyl group, etc.), aryloxycarbonyl group (preferably having 7 to 20, more preferably 7 to 16, particularly preferably 7 to 10 carbon atoms such as phenyloxy A carbonyl group, etc.), an acyloxy group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16, particularly preferably 2 to 10, and examples thereof include an acetoxy group and a benzoyloxy group. ), An acylamino group (preferably having 2 to 20 carbon atoms, more preferably 2 to 16 and particularly preferably 2 to 10 such as acetylamino group and benzoylamino group), alkoxycarbonylamino group ( Preferably it has 2 to 20 carbon atoms, more preferably 2 to 16 carbon atoms, particularly preferably 2 to 12 carbon atoms, such as a methoxycarbonylamino group, and an aryloxycarbonylamino group (preferably 7 to 7 carbon atoms). 20, more preferably 7 to 16, particularly preferably 7 to 12, and examples thereof include a phenyloxycarbonylamino group), a sulfonylamino group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms). And particularly preferably 1 to 12, for example, methanesulfonylamino group, benzenesulfonate Amino groups, etc.), sulfamoyl groups (preferably having 0 to 20 carbon atoms, more preferably 0 to 16 carbon atoms, particularly preferably 0 to 12 carbon atoms such as sulfamoyl group, methylsulfamoyl group, dimethylsulfayl group). And a carbamoyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 carbon atoms, particularly preferably 1 to 12 carbon atoms such as a carbamoyl group and a methylcarbamoyl group). , Diethylcarbamoyl group, phenylcarbamoyl group, etc.), alkylthio group (preferably having 1 to 20, more preferably 1 to 16, particularly preferably 1 to 12 carbon atoms, such as methylthio group and ethylthio group) Arylthio group (preferably having 6 to 20 carbon atoms, More preferably, it is 6 to 16, particularly preferably 6 to 12, and examples thereof include a phenylthio group.), A sulfonyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, and particularly preferably 1 to 1). 12 such as a mesyl group and a tosyl group), a sulfinyl group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16 and particularly preferably 1 to 12, such as a methanesulfinyl group, Benzenesulfinyl group, etc.), urethane group, ureido group (preferably having 1 to 20 carbon atoms, more preferably 1 to 16, particularly preferably 1 to 12, such as ureido group, methylureido group, phenyl group) Ureido groups, etc.), phosphoric acid amide groups (preferably having 1-20 carbon atoms, more preferably 1-16, 1 to 12 is preferable, and examples thereof include diethyl phosphoric acid amide and phenyl phosphoric acid amide. ), Hydroxy group, mercapto group, halogen atom (eg fluorine atom, chlorine atom, bromine atom, iodine atom), cyano group, sulfo group, carboxyl group, nitro group, hydroxamic acid group, sulfino group, hydrazino group, imino group, Heterocyclic group (preferably having 1 to 30 carbon atoms, more preferably 1 to 12 carbon atoms, and examples of the hetero atom include a nitrogen atom, an oxygen atom, a sulfur atom, specifically, for example, an imidazolyl group, a pyridyl group, a quinolyl group , A furyl group, a piperidyl group, a morpholino group, a benzoxazolyl group, a benzimidazolyl group, a benzthiazolyl group, and the like, and a silyl group (preferably having 3 to 40 carbon atoms, more preferably 3 to 30 carbon atoms, Particularly preferred is 3 to 24, and examples thereof include a trimethylsilyl group and a triphenylsilyl group. That).
These substituents may further have a substituent. Moreover, when there are two or more substituents, they may be the same or different. Further, adjacent substituents may be connected to each other to form a ring.

The laminate of the present invention has excellent adhesion between layers in the laminate and can suppress deterioration of the polarizer over time under high-temperature and high-humidity conditions by forming a thin film and overlapping the polarizer. Moreover, the laminated body of this invention can suppress the raise over time of a haze value also in a high temperature environment. The polarizing plate and the image display device of the present invention have the laminate of the present invention that exhibits the above effects, and the deterioration of the polarizer can be effectively suppressed even under high temperature and high humidity conditions.
In the present specification, the degree of suppressing the deterioration of the polarizer under high temperature and high humidity conditions is also referred to as “polarizer durability” or “polarizing plate durability”.
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 an embodiment of the laminate of the present invention. FIG. 2 is a schematic diagram showing an outline of an embodiment of a liquid crystal display device including a polarizing plate incorporating the polarizing plate protective film of the present invention.

Preferred embodiments of the present invention are described below.
[Laminate]
As shown in FIG. 1, the laminate of the present invention has a cellulose ester resin layer 11 and a repeating unit that is directly provided on the cellulose ester resin layer 11 and represented by the following general formula (1). In addition, a layer 12 containing a polymer having a glass transition temperature higher than a specific temperature (hereinafter also simply referred to as “polymer layer”) is included. Details of the cellulose ester resin layer 11 and the polymer layer 12 will be described later. In the laminate of the present invention, the polymer layer may be provided on one side of the cellulose ester resin layer 11 as shown in FIG. 1, or the polymer layer may be provided on both sides of the cellulose ester resin layer 11. There may be. More preferably, the laminate of the present invention has a form in which the polymer layer is provided on one side of the cellulose ester resin layer 11.
Two or more polymer layers having different compositions may be provided on the cellulose ester resin layer. When two or more polymer layers are formed, two or more polymer layers may be provided on one side of the cellulose ester resin layer, and two or more polymer layers may be provided on both sides of the cellulose ester resin layer. .

Moreover, the laminate of the present invention may have various functional layers (not shown) specialized for specific functions in addition to the cellulose ester resin layer 11 and the polymer layer 12. Examples of such a functional layer include a hard coat layer, an antireflection layer, a light scattering layer, an antifouling layer, and an antistatic layer.

<Polymer layer>
The polymer layer which comprises the laminated body of this invention is demonstrated.

In the present invention, the “polymer layer” refers to a polymer having a repeating unit of the general formula (1) described later and having a glass transition temperature of 50 ° C. or higher (hereinafter referred to as “polymer (S)”. The term “polymer” refers to a polymer (S) or a polymer corresponding thereto (for example, a polymer to be compared with the polymer (S), and not a cellulose ester resin) unless otherwise specified. It means a layer containing 50% by mass or more. Here, the content of the polymer (S) in the polymer layer is preferably 60% by mass or more, more preferably 70% by mass or more, further preferably 80% by mass or more, and particularly preferably 85% by mass or more. The higher the content of the polymer (S) in the polymer layer, the higher the adhesion to the cellulose ester resin layer, and the deterioration of the optical properties of the laminate and the deterioration of the polarizer when used as a protective film. Is preferable in that it can be further suppressed. Therefore, the content of the polymer (S) in the polymer layer may be 100% by mass, and is usually 99% by mass or less. When the content of the polymer (S) in the polymer layer is not 100% by mass, the balance can contain various conventional additives or resins. Examples of such additives include plasticizers, organic acids, dyes, polymers, retardation modifiers, ultraviolet absorbers, antioxidants, matting agents, and the like.

-Polymer (S)-
The polymer (S) constituting the polymer layer has a repeating unit represented by the following general formula (1).

In the general formula (1), R ^a represents a hydrogen atom, an alkyl group or an alkoxycarbonyl group.
When R ^a is an alkyl group, the alkyl group may be linear or branched. The alkyl group preferably has 1 to 20 carbon atoms, more preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and particularly preferably 1 to 4. Preferable specific examples of this alkyl group include methyl, ethyl, propyl, isopropyl, n-butyl, t-butyl, s-butyl and isobutyl.

When R ^a is an alkoxycarbonyl group, the alkoxycarbonyl group may be linear or branched. The alkoxycarbonyl group preferably has 2 to 20 carbon atoms, more preferably 2 to 10 carbon atoms, further preferably 2 to 8 carbon atoms, and further preferably 2 to 4 carbon atoms. Preferable specific examples of this alkoxycarbonyl group include methoxycarbonyl, ethoxycarbonyl and the like.

R ^a is more preferably a hydrogen atom or methyl.

R ^b and R ^c represent a hydrogen atom, an alkyl group, an aryl group or an alkoxycarbonyl group.
When R ^b and R ^c are alkyl groups, the alkyl group may be linear or branched. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 5, more preferably 1 to 3, more preferably methyl or ethyl, and still more preferably methyl.
When R ^b and R ^c are an aryl group, the aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 15 carbon atoms, particularly preferably 6 to 12 carbon atoms, and particularly preferably phenyl.
When R ^b and R ^c are alkoxycarbonyl groups, the alkoxycarbonyl group preferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms, and still more preferably methoxycarbonyl or ethoxycarbonyl.
R ^b and R ^c are more preferably a hydrogen atom.

L ¹ represents a divalent linking group formed by combining two or more divalent groups selected from an alkylene group, an arylene group, —C (═O) —, —O—, and —NR ³ —. However, L ¹ includes a group represented by —C (═O) NR ³ — in its structure. The number of —C (═O) NR ³ — in L ¹ is preferably 1 to 3, more preferably 1 or 2, and even more preferably 1. Incidentally, ^{L 1} is ^-NR 3 C in its structure (= O) NR ³ - if it contains structure (urea bond) of the ^{-NR 3 C (= O) NR} 3 - -C having the (= O) The number of NR ³ − is one.
There is no particular limitation on the direction in which —C (═O) NR ³ — is incorporated into L ¹ . That is, in the form in which L ¹ includes a group represented by —C (═O) NR ³ —, the form in which the C (═O) side of —C (═O) NR ³ — is bonded to the R ² side, In addition, both forms in which the NR ³ side of —C (═O) NR ³ — is bonded to the R ² side are included.

R ³ represents a hydrogen atom or a substituent. When R ³ is a substituent, examples of the substituent include a group selected from the substituent group T described above, and an alkyl group is particularly preferable. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and still more preferably methyl or ethyl.
R ³ is preferably a group bonded to a nitrogen atom in —C (═O) NR ³ — by a carbonyl group. In this case, R ³ preferably takes a form in which R ³ is bonded to the substituent of R ² . In this case, R ² is preferably an aryl group (preferably a phenyl group).
Of these, R ³ is preferably a hydrogen atom.

The alkylene group that can constitute L ¹ may be linear or branched. The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, and still more preferably 1 to 3 carbon atoms.

The arylene group that can constitute L ¹ preferably has 6 to 20 carbon atoms, and more preferably 6 to 15 carbon atoms. 6 to 12 are more preferable, and a phenylene group is more preferable.

L ¹ is preferably a divalent linking group formed by combining two or more divalent groups selected from an alkylene group, —C (═O) —, —O—, and —NR ³ —.
L ¹ has a molecular weight of preferably 12 to 240, more preferably 44 to 150.

R ² represents an alkyl group, a cycloalkyl group or an aryl group. Here, in the present invention, the structure of R ² does not include any of —C (═O) —, an oxygen atom, and a nitrogen atom. That is, when R ² is an alkyl group, a cycloalkyl group, or an aryl group, when these alkyl group, cycloalkyl group, and aryl group are in a form having a substituent, the substituent includes a carbonyl group, an oxygen atom And nitrogen atoms are not included.

In the general formula (1), when R ² is an alkyl group, the alkyl group is interpreted to be as long as possible a long-chain alkyl group (an alkyl group having the largest number of carbon atoms). For example, if L ¹ does not have an alkylene group at the R ² side end and R ² is ethyl, this form is, in a different way, L ¹ has methylene at the R ² side end and R ² Can also be interpreted as the form in which is methyl. However, in the present invention, this form is interpreted as R ² is ethyl.

In the general formula (1), when R ² is an aryl group, the aryl group should be interpreted as an aryl group having a molecular weight as large as possible. For example, L ¹ is as free an arylene group R ² side end, and a phenylene when R ² is a phenyl group having a phenyl as a substituent, if this form another point of view, L ¹ is the R ² side end And R ² is phenyl. However, in the present invention, this form is interpreted as a phenyl group in which R ² has phenyl as a substituent.

When R ² is an alkyl group, the alkyl group may be linear or branched. Further, it may be unsubstituted or may have a substituent. The alkyl group preferably has 1 to 12 carbon atoms, more preferably 1 to 10, more preferably 1 to 8, still more preferably 1 to 6, and further preferably 1 to 4. In addition, when L ¹ has a form having —NR ³ — at the R ² side terminal, the alkyl group R ² may be linked to R ³ to form a ring. Examples of such a ring structure include a morpholine ring, a pyrrolidone ring, an imidazolidone ring, and a succinimide ring, and a morpholine ring is preferred.

When R ² is a cycloalkyl group, the cycloalkyl group may be unsubstituted or may have a substituent. The cycloalkyl preferably has 6 to 20 carbon atoms, more preferably 6 to 15 carbon atoms, still more preferably 6 to 12 carbon atoms, and even more preferably a cyclopentyl group or a cyclohexyl group.

When R ² is an aryl group, the aryl group may be unsubstituted or may have a substituent. The aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 15 carbon atoms, still more preferably 6 to 12 carbon atoms, and particularly preferably a phenyl group.

The repeating unit represented by the general formula (1) is preferably a repeating unit represented by the following general formula (2) or (3).

 

In general formula (2), R ^1a represents a hydrogen atom or methyl. R ² has the same meaning as R ² in the general formula (1), and the preferred form is also the same.

L ² represents an alkylene group, an alkyleneoxy group or a polyalkyleneoxy group.
When L ² is an alkylene group, the alkylene group may be linear or branched, and is preferably linear. The alkylene group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, more preferably 1 to 4, still more preferably 1 to 3, and particularly preferably ethylene.
When L ² is an alkyleneoxy group, the alkyleneoxy group may be linear or branched, and is preferably linear. The alkyleneoxy group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, more preferably 1 to 4, and still more preferably 1 to 3.
When L ² is a polyalkyleneoxy group, the alkyleneoxy group constituting the polyalkyleneoxy group may be linear or branched, and is preferably linear. The alkyleneoxy group constituting the polyalkyleneoxy group preferably has 1 to 10 carbon atoms, more preferably 1 to 6, more preferably 1 to 4, and still more preferably 1 to 3. The total number of carbon atoms of the polyalkyleneoxy group is preferably 1 to 10, more preferably 1 to 6. The oxygen number of the polyalkyleneoxy group is preferably 1 to 4, more preferably 1 to 3, and particularly preferably 1 to 2. When L ² is a polyalkyleneoxy group, the alkyleneoxy groups constituting the polyalkyleneoxy group may be the same or different.
L ² is particularly preferably an ethyleneoxy group.
When L ² is an alkyleneoxy group or a polyalkyleneoxy group, an oxygen atom in the alkyleneoxy group or polyalkyleneoxy group is linked to A.

A represents —C (═O) NR ³ — or —NR ³ —C (═O) —NR ³ —. R ³ has the same meaning as R ³ described in the general formula (1), and the preferred form is also the same. When A is —C (═O) NR ³ —, the direction is not limited. ^{That, -C (= O) NR 3} - in NR ³ is may be oriented on the side of the ^{L 2} may face the side of ^{R 2.}

 

In the general formula ^{(3), R 1a} and ^{R 2} each have the same meaning as ^{R 1a} and ^{R 2} in the general formula (2), a preferred form also the same.

R ^3a represents a hydrogen atom or an alkyl group.
When R ^3a is an alkyl group, the alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and still more preferably methyl or ethyl.
When R ² and R ^3a are both alkyl groups, they may be linked to each other to form a ring. The ring atoms of this ring structure may contain heteroatoms other than nitrogen atoms. Specific examples of this ring structure include a morpholine ring, a pyrrolidone ring, an imidazolidone ring, and a succinimide ring, and a morpholine ring is preferred.

The repeating unit represented by the general formula (1) is more preferably a repeating unit represented by the following general formula (4).

In the general formula ^{(4), R 1a} and ^{R 2} each have the same meaning as ^{R 1a} and ^{R 2} in the general formula (3), a preferred form also the same.

Preferred specific examples of the compound represented by the general formula (1) are shown below, but the present invention is not limited to these forms.

 

The polymer (S) may consist of only the repeating unit represented by the general formula (1) or may have a repeating unit other than the repeating unit represented by the general formula (1). . The content of the repeating unit represented by the general formula (1) in the polymer (S) is preferably 10 to 100% by mass, and more preferably 20 to 100% by mass.

The polymer (S) has physical properties that are easily dissolved in a coating solvent used when forming the cellulose ester resin layer, and is excellent in recyclability. In the production of the laminate of the present invention, after forming a laminated structure having a cellulose resin layer and a polymer layer, the obtained laminate is cut into a desired size and shipped. It is assumed that the cut unnecessary pieces are mixed and recycled within a range that is allowed in the material forming the cellulose ester resin layer (within a range that does not impair desired optical properties and the like). In that case, the polymer (S) is sufficiently dissolved in the coating solvent used to form the cellulose ester resin layer, and the polymer (S) and the cellulose ester resin are homogeneously mixed in the coating solvent. There is a need. The polymer (S) is excellent in solubility in such a solvent and excellent in recyclability.
The polymer (S) also preferably has a repeating unit represented by the following general formula (5). By having a repeating unit represented by the following general formula (5), the solubility in the coating solvent can be further increased, and the recyclability described above can be further improved.

In general formula (5), R ⁶ represents a hydrogen atom or an alkyl group.
When R ⁶ is an alkyl group, the alkyl group may be linear or branched. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 5 carbon atoms, and still more preferably 1 to 3 carbon atoms. R ⁶ is more preferably methyl or ethyl, and even more preferably methyl.
R ⁶ is more preferably a hydrogen atom or methyl.

R ⁴ and R ⁵ represent a hydrogen atom, an alkyl group, an aryl group or an alkoxycarbonyl group.
When R ⁴ and R ⁵ are alkyl groups, the alkyl group may be linear or branched. The alkyl group preferably has 1 to 10 carbon atoms, more preferably 1 to 5, more preferably 1 to 3, more preferably methyl or ethyl, and still more preferably methyl.
When R ⁴ and R ⁵ are an aryl group, the aryl group preferably has 6 to 20 carbon atoms, more preferably 6 to 15 carbon atoms, particularly preferably 6 to 12 carbon atoms, and particularly preferably phenyl.
When R ⁴ and R ⁵ are alkoxycarbonyl groups, the alkoxycarbonyl group preferably has 2 to 10 carbon atoms, more preferably 2 to 5 carbon atoms, and still more preferably methoxycarbonyl or ethoxycarbonyl.
R ⁴ and R ⁵ are more preferably a hydrogen atom.

L ³ is a single bond, or a divalent group selected from an alkylene group, an arylene group, —C (═O) —, —O— and —NR ^3A —, or a combination of two or more of these groups And a divalent linking group.
R ^3A represents a hydrogen atom or a substituent. When R ^3A is a substituent, examples of the substituent include a group selected from the substituent group T described above, and an alkyl group is particularly preferable. The alkyl group preferably has 1 to 6 carbon atoms, more preferably 1 to 4 carbon atoms, and still more preferably methyl or ethyl.
In the divalent linking group formed by combining two or more of the above, the number of the linking groups to be combined is not particularly limited, but is preferably 2 to 9, and more preferably 2 or 3. Also, the combination of the linking groups is not particularly limited. For example, the combination of —C (═O) —, —O— and an alkylene group, or the combination of —C (═O) —, —O— and an arylene group. And a combination of —C (═O) —, —O— and an alkylene group is more preferred. Among these, it is more preferable that L ³ is a linking group containing —C (═O) —, and —C (═O) — is bonded to the main chain (the carbon atom to which R ⁶ is bonded).

The alkylene group L ³ or the alkylene group incorporated in L ³ is preferably linear. The alkylene group preferably has 1 to 5 carbon atoms, more preferably 1 to 4, more preferably 1 to 3, and particularly preferably 2.
The arylene group L ³ or the arylene group incorporated in L ³ preferably has 6 to 20 carbon atoms, more preferably 6 to 15 carbon atoms, particularly preferably 6 to 12 carbon atoms, and particularly preferably phenylene.

Preferred specific examples of the repeating unit represented by the general formula (5) are shown below, but the present invention is not limited to these examples.

When the polymer (S) has a repeating unit represented by the general formula (5), the content of the repeating unit represented by the general formula (5) in the polymer (S) is 5 to 30% by mass. 10 to 20% by mass is more preferable.

When the polymer (S) contains a repeating unit other than the repeating unit represented by the general formula (1) together with the repeating unit represented by the general formula (1), The remainder excluding the repeating unit represented by the general formula (1) is not included in the repeating unit represented by the general formula (5) and / or the repeating unit represented by the general formula (1). And it is preferable to be comprised by the repeating unit derived from the (meth) acrylic acid ester which is not included in the repeating unit represented by the said General formula (5). (Hereinafter, a repeating unit derived from a (meth) acrylic acid ester not included in the repeating unit represented by the general formula (1) and not included in the repeating unit represented by the general formula (5) is referred to as “repeating Unit (R) ")
As said repeating unit (R), the repeating unit derived from (meth) acrylic-acid alkylester is more preferable. Preferable specific examples of the repeating unit (R) include, for example, a repeating unit derived from benzyl (meth) acrylate, a repeating unit derived from methyl (meth) acrylate, a repeating unit derived from ethyl (meth) acrylate, and phenoxyethyl (meth) acrylate. Repeating units derived from isopropyl (meth) acrylate, repeating units derived from n-butyl (meth) acrylate, repeating units derived from isobutyl (meth) acrylate, repeating units derived from ethylhexyl (meth) acrylate, cyclohexyl (meth ) A repeating unit derived from acrylate, a repeating unit derived from isobornyl (meth) acrylate, and a repeating unit derived from dicyclopentenyloxyethyl (meth) acrylate.

In the polymer (S), in the total molar amount of the repeating unit represented by the general formula (1), the repeating unit represented by the general formula (5), and the repeating unit (R), the general formula The molar amount of the repeating unit represented by (1) is preferably 10 to 100 mol%, more preferably 15 to 100 mol%, and further preferably 20 to 95 mol%.
Further, when the polymer (S) has a repeating unit represented by the general formula (5), the repeating unit represented by the general formula (1) in the polymer (S) and the general formula (1) In the total molar amount of the repeating unit represented by 5) and the repeating unit (R), the molar amount of the repeating unit represented by the general formula (5) is preferably 5 to 50 mol%, and preferably 10 to 40 mol%. Is more preferable, and 15 to 30 mol% is still more preferable.
Moreover, when the said polymer (S) has the said repeating unit (R), in the said polymer (S), it represents with the repeating unit represented by the said General formula (1), and the said General formula (5). In the total molar amount of the repeating unit and the repeating unit (R), the molar amount of the repeating unit (R) is preferably 10 to 95 mol%, more preferably 10 to 90 mol%, and further preferably 20 to 90 mol%.

The polymer (S) has a glass transition temperature (Tg) of 50 ° C. or higher. From the viewpoint of further improving durability under high temperature and high humidity conditions, the Tg of the polymer (S) is preferably 70 ° C or higher, more preferably 80 ° C or higher, further preferably 90 ° C or higher, and further preferably 95 ° C or higher. There is no restriction | limiting in particular in the upper limit of Tg of the said polymer (S), It is practical to set it as 180 degrees C or less, and it is 130 degrees C or less normally. That is, the polymer (S) has physical properties different from those of the polymers used as adhesives or pressure-sensitive adhesives.

In the present invention, Tg is measured using a differential scanning calorimeter (DSC).
In the present invention, the methods described in Examples described later can be used. As the measurement sample, in addition to the polymer powder itself, a powder obtained by scraping the polymer layer from the laminate may be used. In addition, when using the powder which removed the polymer layer from the laminated body, you may remove (purify) components other than a polymer as needed.

The lower limit value of the weight average molecular weight of the polymer (S) is preferably 10,000 or more, more preferably 20,000 or more, and further preferably 30,000, from the viewpoint of film planarity. preferable. On the other hand, the upper limit of the weight average molecular weight of the polymer (S) is preferably 500,000 or less, more preferably 300,000 or less, and 200,000 or less, from the viewpoint of film forming properties. More preferably, it is more preferably 150,000 or less.
The weight average molecular weight can be measured by the method described in Examples described later.

The polymer (S) can be obtained by polymerizing a monomer that leads each of the above repeating units by a conventional method. For example, it can be obtained by polymerizing a monomer by heat treatment and / or light irradiation in the presence of a thermal polymerization initiator and / or a photopolymerization initiator.

In the present invention, the film thickness of the polymer layer is not particularly limited, preferably 1 to 25 μm, more preferably 2 to 20 μm, particularly preferably 1 to 15 μm. The film thickness of the polymer layer is preferably 2 to 15 μm, preferably 3 to 15 μm, and preferably 5 to 15 μm.

[Cellulose ester resin layer]
The cellulose ester resin layer which comprises the laminated body of this invention is a layer which contains 50 mass% or more of cellulose esters in a layer. 60 mass% or more is preferable, as for content of the cellulose ester in a cellulose-ester resin layer, 70 mass% or more is more preferable, 80 mass% or more is further more preferable, and 85 mass% or more is further more preferable. The upper limit of the content of the cellulose ester in the cellulose ester resin layer is usually 96% by mass or less, preferably 95% by mass or less, and more preferably 92% by mass or less. In this case, the remainder excluding the cellulose ester includes, for example, additives described later.

<Cellulose ester>
The cellulose ester used as a raw material in the production of the cellulose ester resin layer of the present invention will be described.
The cellulose ester raw material cellulose used in the present invention includes cotton linter, wood pulp (hardwood pulp, softwood pulp), etc., and any cellulose obtained from any raw material cellulose can be used. May be. 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.
As a cellulose ester, the well-known cellulose ester used for manufacture of a cellulose-ester film can be used without a restriction | limiting at all. Of these, cellulose acylate is preferably used.

(Cellulose acylate)
As the cellulose acylate used in the present invention, a known cellulose acylate used for producing a cellulose acylate film can be used without any limitation.
The β-1,4-bonded glucose unit constituting cellulose has free hydroxy groups at the 2nd, 3rd and 6th positions. Cellulose acylate is a polymer obtained by acylating a part of these hydroxy groups with an acyl group.
The degree of acyl substitution (hereinafter sometimes simply referred to as “degree of substitution”) indicates the degree of acylation of the hydroxy group of cellulose located at the 2-position, 3-position and 6-position, and is 2 for all glucose units. When the hydroxy groups at the 3rd, 6th and 6th positions are all acylated, the total degree of acyl substitution is 3. For example, in all glucose units, when only the 6-position is all acylated, the total acyl substitution degree is 1. Similarly, the total acyl substitution degree is 1 when all of any one of the 6-position and 2-position is acylated in each glucose unit in all hydroxy groups of all glucose.
That is, the degree of substitution indicates the degree of acylation, assuming that 3 is when all the hydroxy groups in the glucose molecule are all acylated.
The degree of substitution of cellulose acylate is described in Tezuka et al., Carbohydrate. Res. , 273, 83-91 (1995), or according to the method prescribed in ASTM-D817-96.

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

The acyl group of the cellulose acylate used in the present invention is not particularly limited, and may be a form having one kind of acyl group or a form having two or more kinds of 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, cyclohexanecarbonyl 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 preferably used in the present invention. The total acyl substitution degree of this cellulose acetate is 2.00 to 3 from the viewpoint of moisture permeability and optical properties. Is preferably 0.000, more preferably 2.20 to 3.00, still more preferably 2.30 to 3.00, still more preferably 2.30 to 2.97, Particularly preferred is 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. Also, 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 be preferably used. Among them, the acyl group of the mixed fatty acid ester preferably includes an acetyl group and an acyl group having 3 to 4 carbon atoms. When the mixed fatty acid ester contains an acetyl group as an acyl group, the degree of acetyl substitution is preferably less than 2.5 and more preferably less than 1.9. On the other hand, when an acyl group having 3 to 4 carbon atoms is contained, the degree of substitution of the acyl group having 3 to 4 carbon atoms is preferably 0.1 to 1.5, and preferably 0.2 to 1.2. Is more preferable, and 0.5 to 1.1 is particularly preferable.
As the cellulose ester resin layer used in the present invention, it is also preferable to employ a resin layer composed of a plurality of layers composed of different cellulose acylates by a co-casting method described later.

The cellulose ester or cellulose acylate used in the present invention preferably has a degree of polymerization of 250 to 800, more preferably 300 to 600. The number average molecular weight of the cellulose ester or cellulose acylate used in the present invention is preferably 40000 to 230,000, more preferably 60000 to 230,000, and most preferably 75,000 to 200000. The degree of polymerization can be determined by dividing the number average molecular weight measured in terms of polystyrene by gel permeation chromatography (GPC) by the molecular weight of the glucopyranose unit of cellulose ester or cellulose acylate.

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

Further, in the cellulose ester resin layer of the present invention, other resins (for example, (meth) acrylic resin etc.) can be used in combination with the cellulose ester within a range not impairing the effects of the present invention. The content of the other resin in the cellulose ester film is preferably 40% by mass or less, more preferably 30% by mass or less, further preferably 20% by mass or less, and further preferably 15% by mass or less in the cellulose ester film. 10 mass% or less is still more preferable.

<Formation of cellulose ester resin layer>
Next, the formation of the cellulose ester resin layer will be described.
The formation of the cellulose ester resin layer is not particularly limited. For example, the cellulose ester resin layer is preferably formed by a melt film formation method or a solution film formation method (solvent casting method). More preferably, it is formed by a film forming method (solvent casting method). Examples of film production using the solvent cast method are described in U.S. Pat. Nos. 2,336,310, 2,367,603, 2,492,078, 2,492,977, Nos. 2,492,978, 2,607,704, 2,739,069 and 2,739,070, British Patent Nos. 640731 and 736892 And the Japanese Patent Publications Nos. 45-4554, 49-5614, JP-A-60-176834, JP-A-60-203430, and JP-A-62-115035. Moreover, the said cellulose-ester resin layer may be extended | stretched. For the stretching method and conditions, refer to, for example, JP-A-62-115035, JP-A-4-152125, 4-284221, 4-298310, and 11-48271. can do.

(Casting)
As a method of casting the solution, a method of uniformly extruding the prepared dope from a pressure die onto a metal support, a doctor blade for adjusting the film thickness with a blade of the dope once cast on a support of metal or the like And a method using a reverse roll coater that adjusts with a reversely rotating roll, and a method using a pressure die is preferred. The pressure die includes a coat hanger type and a T die type, and any of them can be preferably used. In addition to the methods listed here, it can be carried out by various 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.

The cellulose ester resin layer may be a single layer or multiple layers, and in the case of multiple layers, it is preferable to use a lamination casting method such as a co-casting method, a sequential casting method, or a coating method. In particular, the simultaneous co-casting (also referred to as simultaneous multi-layer co-casting) method is particularly preferable from the viewpoint of stable production and production cost reduction.
When producing a cellulose ester resin layer by the co-casting method and the sequential casting method, first, a cellulose ester solution (also referred to as a dope) for each layer is prepared, and this solution is cast on a support.
In the co-casting method (multi-layer simultaneous casting), first, a casting dope for each layer (which may be three layers or more) is simultaneously applied from a separate slit or the like on a casting support (band or drum). The dope is extruded using a casting die that can be extruded, and the layers are cast simultaneously. It is a casting method in which after casting, the film is peeled off from the support after an appropriate time and dried to form a film. By using a co-casting die, for example, a total of three layers: a surface layer two layers formed from a surface layer dope on a casting support, and a core layer composed of a core layer dope sandwiched between these surface layers. It can be extruded and cast simultaneously on a support.

In the sequential casting method, the casting dope for the first layer is first extruded from the casting die on the casting support, cast, and dried on the second layer without drying or drying. The dope for casting is extruded from the casting die, and if necessary, the dope is cast and laminated sequentially up to the third layer or more, and peeled off from the support after a suitable time and dried. Then, a cellulose ester resin layer is formed.
In the coating method, generally, a core layer is formed into a film by a solution casting method, and a coating solution that is a target cellulose ester solution is applied to the surface layer, followed by drying to form a cellulose ester having a laminated structure. A resin layer is formed.

(Stretching)
The cellulose ester resin layer is preferably stretched after casting and drying. The stretching direction of the cellulose ester resin layer 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. Yes. 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 film is dried, it can be stretched using a stretching machine (preferably uniaxial stretching using a long stretching machine).
In the case of stretching in the MD direction, for example, it can be performed by adjusting the speed of the film transport roller to make the winding speed faster than the film peeling speed.

When the laminate of the present invention is used as a protective film for a polarizer (also referred to as a polarizing plate protective film), in order to suppress light leakage when the polarizing plate is viewed obliquely, the transmission axis of the polarizer and the cellulose ester An embodiment in which slow axes in the plane of the resin layer are arranged in parallel is preferable. Since the transmission axis of the roll film-like polarizer produced continuously is generally parallel to the width direction of the roll film, it is composed of the roll film-like polarizer and the roll film-like cellulose ester resin layer. In order to continuously bond the protective film, the in-plane slow axis of the roll film-shaped protective film needs to be parallel to the width direction of the cellulose ester resin layer. 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.

The stretching in the TD direction is preferably 5 to 100%, more preferably 5 to 80%, and particularly preferably 5 to 40%. In the case of unstretched, the stretching is 0%. 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, and the residual solvent amount = (residual volatile matter mass / film mass after heat treatment) × 100% is stretched in a state of 0.05 to 50%. It is preferable to do. It is more preferable to stretch 5 to 80% in a state where the residual solvent amount is 0.05 to 5%.

<Additives>
The cellulose ester resin layer may contain an additive as long as the effects of the present invention are not impaired. Examples of the additive include known plasticizers, organic acids, dyes, polymers, retardation adjusting agents, ultraviolet absorbers, antioxidants, matting agents, and the like. Regarding these, the description of paragraph numbers 0062 to 0097 of JP2012-155287A can be referred to, and the contents thereof are incorporated in the present specification. Examples of the additive include a peeling accelerator, an organic acid, and a polyvalent carboxylic acid derivative. With respect to these, the description of WO2015 / 005398, paragraphs 0212 to 0219 can be referred to, and the contents thereof are incorporated in the present specification. Furthermore, examples of the additive include a radical scavenger, a deterioration inhibitor, and a barbituric acid compound, which will be described later.
The content of the additive (when the cellulose ester resin layer contains two or more additives) is preferably 50 parts by mass or less with respect to 100 parts by mass of the cellulose ester. 30 parts by mass or less, more preferably 5 to 30 parts by mass.

(Plasticizer)
One preferred additive is a plasticizer. By adding a plasticizer to the cellulose ester resin layer, the hydrophobicity of the cellulose ester resin layer can be increased. This point is preferable from the viewpoint of reducing the water content of the cellulose ester resin layer. The use of such a plasticizer can reduce the occurrence of display unevenness of the image display device due to humidity when the laminate having a cellulose ester resin layer is used as a polarizing plate protective film. preferable.

The molecular weight of the plasticizer is preferably 3000 or less, more preferably 1500 or less, and still more preferably 1000 or less, from the viewpoint of obtaining the above-described effect by adding it satisfactorily. The molecular weight of the plasticizer is, for example, 300 or more, preferably 350 or more, from the viewpoint of low volatility. In the case of multimeric plasticizers, the molecular weight is the number average molecular weight.

As the plasticizer, a polyhydric ester compound of polyhydric alcohol (hereinafter also referred to as “polyhydric alcohol ester plasticizer”), a polycondensed ester compound (hereinafter also referred to as “polycondensed ester plasticizer”), And carbohydrate compounds (hereinafter also referred to as “carbohydrate derivative plasticizers”). For polyhydric alcohol ester plasticizers, WO2015 / 005398 paragraphs 0081 to 0098, for polycondensed ester plasticizers, paragraphs 00099 to 0122, and for carbohydrate derivative plasticizers, paragraphs 0123 to 0140. The contents of which are hereby incorporated by reference. The content of these plasticizers is 1 to 20 parts by mass with respect to 100 parts by mass of the resin (cellulose ester) of the layer to which the plasticizer is added from the viewpoint of achieving both the effect of adding the plasticizer and suppressing the precipitation of the plasticizer. Preferably, the content is 2 to 15 parts by mass, more preferably 5 to 15 parts by mass.
Two or more kinds of these plasticizers may be added. Also when adding 2 or more types, the specific example and preferable range of addition amount are the same as the above.

(Antioxidant)
One preferable additive may include an antioxidant. Regarding the antioxidant, the description of WO 2015/005398, paragraphs 0143 to 0165 can be referred to, and the contents thereof are incorporated in the present specification.

(Radical scavenger)
One preferred additive may include a radical scavenger. Regarding the radical scavenger, reference can be made to the description of WO 2015/005398, paragraphs 0166 to 0199, the contents of which are incorporated herein.

(Deterioration inhibitor)
As one of preferable additives, a deterioration preventing agent can be mentioned. Regarding the deterioration preventing agent, the description in WO2015 / 005398 paragraphs 0205 to 0206 can be referred to, and the contents thereof are incorporated in the present specification.

(Barbituric acid compound)
The cellulose ester resin layer can also contain a compound having a barbituric acid structure (barbituric acid compound). A barbituric acid compound is a compound which can express various functions in a cellulose-ester resin layer by adding this compound. For example, the barbituric acid compound is effective for improving the hardness of the cellulose ester resin layer. The barbituric acid compound is also effective in improving the durability against light, heat, humidity and the like of a polarizing plate provided with a cellulose ester resin layer containing this compound. With respect to the barbituric acid compound that can be added to the cellulose ester resin layer, for example, the description in paragraphs 0029 to 0060 of WO 2015/005398 can be referred to, and the contents thereof are incorporated in the present specification.

<Saponification treatment>
The cellulose ester resin layer can be improved in adhesion to a polarizer material such as polyvinyl alcohol by alkali saponification treatment.
As the saponification method, the method described in paragraph No. 0211 and paragraph No. 0212 of JP-A-2007-86748 can be used.

For example, the alkali saponification treatment for the cellulose ester resin layer is preferably performed in a cycle in which the film surface is immersed in an alkali solution, neutralized with an acidic solution, washed with water and dried. Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution. The concentration of hydroxide ions is preferably in the range of 0.1 to 5.0 mol / L, more preferably in the range of 0.5 to 4.0 mol / L. The alkaline solution temperature is preferably in the range of room temperature to 90 ° C, more preferably in the range of 40 to 70 ° C.

Instead of the alkali saponification treatment, easy adhesion processing as described in JP-A-6-94915 and JP-A-6-118232 may be performed.

The film thickness of the cellulose ester resin layer is preferably 1 to 80 μm, more preferably 1 to 60 μm, and further preferably 3 to 60 μm. The film thickness of the cellulose ester resin layer is preferably 10 to 60 μm, more preferably 20 to 60 μm, and also preferably 20 to 50 μm.

[Manufacturing method of laminate]
The manufacturing method of the laminated body of this invention is demonstrated.
The manufacturing method of the laminated body of this invention is not specifically limited, A well-known method is employable. In addition to the melt film forming method and the solution film forming method (solvent cast method), after preparing the cellulose ester resin layer, a layer containing the polymer (S) is formed by various known coating methods, and this is dried to obtain a laminate. Can also be manufactured. Although there is no restriction | limiting in particular as said application | coating method, A micro gravure coating system can be used preferably. In any case, any coating method may be used as long as the monomer is dissolved in an appropriate solvent at an appropriate concentration. There is no particular limitation.
In addition, from the viewpoint of suitability for mass production, the film can be formed by a melt film forming method or a solution film forming method (solvent casting method). As the melt film forming method, it is preferable to use a manufacturing method such as a T-die method, and it is particularly preferable to use a simultaneous coextrusion method. As the solution casting method, it is preferable to use a lamination casting method such as the above-mentioned co-casting method, sequential casting method, coating method or the like, and particularly a simultaneous co-casting method (also referred to as simultaneous multi-layer co-casting) method is used. Is particularly preferable from the viewpoints of stable production and production cost reduction.

In the laminate of the present invention, the content of the polymer (S) in the laminate is preferably 1 to 30% by mass, more preferably 5 to 28% by mass, and further preferably 8 to 25% by mass. By setting the content of the polymer (S) in the laminate within the preferred range, interlayer adhesion can be further improved.

<Physical properties of the laminate>
(Haze value)
The laminate of the present invention preferably has a total haze value of 2.00% or less. When the total haze value is 2.00% or less, the laminate has high transparency, and is effective in improving the contrast ratio and brightness of the liquid crystal display device. The total haze value is more preferably 1.00% or less, further preferably 0.50% or less, particularly preferably 0.30% or less, and most preferably 0.20% or less. The lower the total haze value, the better the optical performance, but it is preferably 0.01% or more considering raw material selection, production control, roll film handling properties, and the like.
The internal haze value of the laminate of the present invention is preferably 1.00% or less. By setting the internal haze value to 1.00% or less, the contrast ratio of the liquid crystal display device can be improved and excellent display characteristics can be realized. The internal haze value is more preferably 0.50% or less, further preferably 0.20% or less, particularly preferably 0.10% or less, and most preferably 0.05% or less. From the viewpoint of raw material selection, production control, etc., 0.01% or more is preferable.
In particular, the laminate of the present invention preferably has a total haze value of 0.30% or less and an internal haze value of 0.10% or less.
Total haze value and internal haze value are the type of film material, amount added, selection of additives (particularly, particle size, refractive index, amount added), and film production conditions (stretching temperature and stretching) The magnification can be adjusted.
The haze value can be measured on a film sample of 40 mm × 80 mm at 25 ° C. and a relative humidity of 60% with a haze meter (HGM-2DP, Suga Test Machine) according to JIS K-7136 (2000).

(Film thickness)
The film thickness of the laminate of the present invention can be appropriately determined according to the application, but can be set to, for example, 5 to 100 μm. When the thickness is 5 μm or more, the handling property when producing a web-like film is improved, which is preferable. Moreover, by setting it as 100 micrometers or less, it becomes easy to respond to a humidity change and it becomes easy to maintain an optical characteristic. The film thickness of the laminate is more preferably 8 to 80 μm, still more preferably 10 to 70 μm.

(Moisture permeability)
The moisture permeability of the laminate is measured under the conditions of 40 ° C. and relative humidity 90% based on JIS Z-0208.
The moisture permeability of the laminate of the present invention is preferably 1600 g / m ² / day (24 hours) or less, more preferably 1000 g / m ² / day or less, and 600 g / m ² / day or less. More preferably, it is particularly preferably 200 g / m ² / day or less. By controlling the moisture permeability of the laminated body within the above range, the liquid crystal display device mounted with the laminated body of the present invention is warped or displayed during black display after normal temperature, high humidity and high temperature and high humidity environments. Unevenness can be suppressed.

(Moisture content)
The moisture content of the laminate (equilibrium moisture content) is 25 ° C., regardless of the film thickness, so as not to impair the adhesion with a hydrophilic thermoplastic resin such as polyvinyl alcohol when used as a protective film for a polarizing plate. The water content at a relative humidity of 80% is preferably 0 to 4.0% 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 4.0% by mass or less, the dependence of retardation on humidity changes does not become too large, and the display unevenness of the liquid crystal display device during black display after aging at room temperature, high humidity, and high temperature and high humidity. Is also preferred from the standpoint of deterrence.
The moisture content is measured by measuring the film sample 7 mm x 35 mm by the Karl Fischer method using a moisture meter and sample drying devices “CA-03” and “VA-05” (both manufactured by Mitsubishi Chemical Corporation). Can do. The moisture content can be calculated by dividing the moisture content (g) by the sample mass (g).

[Polarizer]
The polarizing plate of the present invention includes a polarizer and at least one laminate of the present invention as a protective film for the 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, the saponification surface of the cellulose ester resin layer in the laminate is bonded to at least one surface of the polarizer using an adhesive. be able to. Examples of the adhesive include an aqueous solution of polyvinyl alcohol or polyvinyl acetal (for example, polyvinyl butyral), a latex of a vinyl-based polymer (for example, polybutyl acrylate), and an ultraviolet curable adhesive. Particularly preferred adhesives are UV curable adhesives or aqueous solutions of fully saponified polyvinyl alcohol.

The production method of the polarizing plate of the present invention is not particularly limited, and can be produced according to a general method. For example, there is a method in which the laminate of the present invention is treated with an alkali and bonded to both surfaces of a polarizer produced by immersing and stretching a polyvinyl alcohol film in an iodine solution using a completely saponified polyvinyl alcohol aqueous solution. 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 treatment as described above may be performed.
When the laminate is in the form in which the polymer layer is provided on one side of the cellulose ester resin layer, the laminate surface of the laminate with the polarizer may be on the polymer layer side or on the cellulose ester resin layer side. But it ’s okay. From the viewpoint of suppressing the absorption of the dye from the polarizer, the polymer layer side is preferably bonded to the polarizer.

The lamination of the laminate of the present invention is preferably bonded to the polarizer so that the transmission axis of the polarizer and the slow axis of the laminate of the present invention are parallel, orthogonal or 45 °. The slow axis can be measured by various known methods, for example, using a birefringence meter (KOBRADH, manufactured by Oji Scientific Instruments).
Here, parallel, orthogonal, or 45 ° includes a range of errors allowed in the technical field to which the present invention belongs. For example, it means that it is within the range of ± 10 ° from the strict angle with respect to parallel, orthogonal and 45 °, respectively, and the error from the strict angle is preferably within the range of ± 5 °, and within the range of ± 3 ° Is more preferable.
The parallel of the transmission axis of the polarizer and the slow axis of the laminate of the present invention means that the direction of the main refractive index nx of the laminate of the present invention 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 laminate of the present invention means that the direction of the main refractive index nx of the laminate of the present invention and the direction of the transmission axis of the polarizer are 90 ° ± 10 °. It means that they intersect at an angle within the range of. 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 is reduced and it is preferable.

The polarizing plate is composed of a polarizer and protective films protecting both surfaces thereof, and at least one of the protective films is preferably a laminate of the present invention. Further, usually, a protective film is bonded to one surface of the polarizing plate, and a separate film is bonded to the other surface. 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.

<Degree of polarization>
In the polarizing plate of the present invention, the degree of polarization is preferably 95.0% or more, more preferably 98.0% or more, and most preferably 99.5% or more.

In the present invention, the degree of polarization of the polarizing plate can be measured using an automatic polarizing film measuring device VAP-7070 manufactured by JASCO Corporation. More specifically, the polarization degree spectrum is calculated from the orthogonal transmittance and the parallel transmittance measured at wavelengths of 380 nm to 700 nm by the following formula, and the weighted average of the light source (auxiliary illuminant C) and the CIE visibility (Y) is calculated. Can be obtained.

Polarization degree (%)
= {(Parallel transmittance−orthogonal transmittance) / (parallel transmittance + orthogonal transmittance)} ^1/2 × 100

<Change in polarization degree>
The polarizing plate of the present invention is excellent in durability under wet heat aging conditions. For this reason, the amount of change in the degree of polarization before and after the polarizing plate durability test described later is small.
The polarizing plate of the present invention was measured for orthogonal transmittance and parallel transmittance using an automatic polarizing film measuring device VAP-7070 manufactured by JASCO Corporation, and the degree of polarization was calculated by the above formula. It is preferable that the amount of change in polarization degree is less than 5% when stored in an environment of 85% humidity for 500 hours.

<Other characteristics>
Other preferable optical characteristics of the polarizing plate of the present invention are described in paragraph Nos. 0238 to 0255 of JP-A-2007-086748, and it is preferable that these characteristics are satisfied.

[Image display device]
The polarizing plate of the present invention is preferably used for an image display device. Examples of such an image display device include a liquid crystal display device and an organic electroluminescence display device. When used for an organic electroluminescence display device, for example, it is used for antireflection applications. Especially, the polarizing plate of this invention is used suitably for a liquid crystal display device.
<Liquid crystal display device>
The liquid crystal display device which is one embodiment as the image display device of the present invention includes a liquid crystal cell and the polarizing plate of the present invention disposed in at least one of the liquid crystal cells.

A preferred embodiment of the liquid crystal display device will be described.
FIG. 2 is a schematic view showing an embodiment of the liquid crystal display device. In FIG. 2, the liquid crystal display device 20 includes a liquid crystal cell having a liquid crystal layer 24 and a liquid crystal cell upper electrode substrate 23 and a liquid crystal cell lower electrode substrate 25 disposed above and below, and upper polarizing plates disposed on both sides of the liquid crystal cell. 21 and the lower polarizing plate 26. 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.

The upper polarizing plate 21 and the lower 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. The polarizing plates 21 and 26 included in the liquid crystal display device 20 of the present invention are the laminate of the present invention as a polarizing plate protective film, a polarizer, and a general transparent protective film in order from the outside of the device (the side far from the liquid crystal cell). A form in which each layer is laminated in order is preferable. Moreover, it replaces with the said general transparent protective film, and the form which used the laminated board of this invention as a phase difference film is also preferable.
The substrate of the liquid crystal cell generally has a thickness of 50 μm to 2 mm.

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

The present invention will be described in more detail based on examples, but the present invention is not limited to the following examples.

[Synthesis example]
<Synthesis Example 1: Synthesis of Polymer P-1>
(2-hydroxymethyl) ethyl acrylate (Tokyo Kasei Co., Ltd.) 20 g, phenyl isocyanate (Tokyo Kasei Co., Ltd.) 19.2 g, butyl acetate 100 ml as a reaction solvent, octyltin compound as a catalyst (trade name: Neostan U -830 (manufactured by Nitto Kasei Co., Ltd.) 70 mg was weighed into a 300 ml flask, and the reaction vessel was heated to 90 ° C. in a nitrogen atmosphere to react. After completion of the reaction, the reaction mixture was concentrated, and the residue was purified by silica gel column chromatography to obtain monomer M-2 (monomer leading to repeating unit A-2). In the following formula, Et represents ethyl.

Subsequently, 15 g of dimethylacetamide was charged into a 200 ml three-necked flask equipped with a stirrer, a thermometer, a reflux condenser, and a nitrogen gas introduction tube, and the temperature was raised to 75 ° C. Under a nitrogen atmosphere, while maintaining the temperature in the reaction vessel at 75 ° C., 16 g of the obtained monomer M-2, 4 g of benzyl methacrylate, 15 g of dimethylacetamide, and “V-601” (manufactured by Wako Pure Chemical Industries, Ltd.) A mixed solution consisting of 13 g was added dropwise at a constant speed so that the addition was completed in 2.5 hours. After completion of dropping, the mixture was further stirred at 75 ° C. for 3 hours. The obtained polymer solution was cooled to room temperature, added to a mixed solvent of 1200 ml of methanol and 300 ml of water, stirred and reprecipitated. The obtained powder was filtered off, further washed with 1000 ml of methanol, and dried at 60 ° C. for 12 hours to obtain polymer P-1.

<Synthesis Examples 2 to 8: Synthesis of Polymers P-2 to P-9>
Polymers P-2 to P-9 shown in Table 1 below were obtained in the same manner as in Synthesis Example 1 except that the monomer type and charge ratio used in Synthesis Example 1 were changed.

<Comparative Synthesis Examples 1 and 2: Synthesis of Comparative Polymers HP-1 and HP-2>
Comparative Polymers HP-1 and HP-2 were obtained in the same manner as in Synthesis Example 1 except that the monomer type and charge ratio used in Synthesis Example 1 were changed as shown in Table 1 below.
In Table 1 below, A-2, A-4, A-5, A-6, A-7, A-9, A-10, and A-11 correspond to the repeating units exemplified above.

Table 1 below shows the weight average molecular weights of the polymers obtained in the above synthesis examples and comparative synthesis examples. As the weight average molecular weight of the polymer, a weight average molecular weight measured in terms of polystyrene by gel permeation chromatography (GPC) was adopted. Specific measurement conditions are shown below.
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)

[Test Example 1: Polymer solubility test]
In a vial, 0.2 g of the polymer synthesized above and a predetermined amount of methylene chloride / methanol (= 80/20 (w / w)) mixed solvent (so that the polymer concentration is 10 wt%, 5 wt%, 1 wt%) The mixture was weighed for 3 hours at room temperature using a rotor (manufactured by ASONE, MIX ROTOR VMR-SR). After completion of stirring, the dissolved state was visually observed and evaluated according to the following evaluation criteria.
(Solubility evaluation criteria)
A: Completely dissolved at 10 wt% B: Completely dissolved at 5 wt%, but not completely dissolved at 10 wt% C: Completely dissolved at 1 wt%, but not completely dissolved at 5 wt% D: Insoluble content at 1 wt% Is shown in Table 1 below.

[Test Example 2: Measurement of glass transition temperature Tg]
Using a differential scanning calorimeter (X-DSC7000 (produced by IT Measurement Control Co., Ltd.)), 20 mg of a polymer sample is placed in a measurement pan, and this is heated from 30 ° C. to 120 ° C. at a rate of 10 ° C./min in a nitrogen stream. The temperature was raised and held for 15 minutes, and then cooled to 30 ° C. at −20 ° C./min. Thereafter, the temperature was raised again from 30 ° C. to 250 ° C., and the temperature at which the baseline began to change from the low temperature side was defined as the glass transition temperature Tg.

[Production Example 1: Production of laminates S-1 to S-9 and comparative laminates HS-2 and HS-3]
<Preparation of Cellulose Ester Resin Layer CA-1>
The following composition was put into a mixing tank, stirred while heating to dissolve each component, and a cellulose acetate solution (dope A) having a solid content concentration of 22% by mass was prepared.
[Composition of Cellulose Acetate Solution (Dope A)]
Cellulose acetate with an acetyl substitution degree of 2.86 100 parts by weight Triphenyl phosphate (plasticizer) 7.8 parts by weight Biphenyl diphenyl phosphate (plasticizer) 3.9 parts by weight Ultraviolet absorber (Tinubin 328 manufactured by Ciba Japan) 0.9 Part by weight Ultraviolet absorber (manufactured by Tinuvin 326 Ciba Japan) 0.2 part by weight Methylene chloride (first solvent) 336 parts by weight Methanol (second solvent) 29 parts by weight 1-butanol (third solvent) 11 parts by weight

Using a band casting apparatus, the prepared dope was uniformly cast from a casting die onto a stainless steel endless band (casting support) having a width of 2000 mm. When the amount of residual solvent in the dope reaches 40% by mass, it is peeled off from the casting support as a polymer film, conveyed without being actively stretched by a tenter, and dried at 130 ° C. in a drying zone. It was. The thickness of the obtained cellulose ester resin layer (cellulose ester film) CA-1 was 55 μm.

<Preparation of cellulose ester resin layer CA-2>
Using the band casting apparatus, the prepared dope was uniformly cast from a casting die onto a stainless steel endless band (casting support) having a width of 2000 mm. When the residual solvent amount in the dope A reaches 40% by mass, the polymer film is peeled from the casting support, and the rotational speed of the downstream roller is made higher than the rotational speed of the upstream roller at the transition portion. Is stretched 1.2 times in the transport direction (MD) at a temperature of 170 ° C. and 1.5 times in the direction perpendicular to the transport direction (TD direction) with a tenter (stretch ratio is 1. 8 times), drying was performed at 130 ° C. in the drying zone. The film thickness of the obtained cellulose ester resin layer (cellulose ester film) CA-2 was 40 μm.

<Preparation of laminate S-1>
The polymer P-1 was mixed with methyl ethyl ketone so as to have a solid content of 15%, charged into a glass separable flask equipped with a stirrer, stirred at room temperature for 5 hours, and filtered through a polypropylene depth filter having a pore size of 5 μm. A composition for forming a polymer layer was obtained. Next, the composition for forming a polymer layer was applied on the cellulose ester resin layer CA-1 prepared above using a gravure coater. Subsequently, it was dried at 25 ° C. for 1 minute and further dried at 120 ° C. for about 5 minutes to obtain a laminate S-1 having a thickness of 60 μm.

<Production of Laminates S-2 to S-10 and Comparative Laminates HS-2 and HS-3>
In the above <Production of laminate S-1>, the polymer P-1 used in the polymer layer forming composition was changed as shown in Table 2 below, and the cellulose ester resin layer was changed as shown in Table 2 below. Produced laminates S-2 to S-10 and comparative laminates HS-2 and HS-3 in the same manner as in <Preparation of laminate S-1>. Each of the obtained laminates had a thickness of 60 μm.

[Production Example 2: Production of polymer mixed monolayer film HS-1]
The production of the cellulose ester resin layer CA-1 was the same as the production of CA-1, except that 100 parts by mass of cellulose acetate having an acetyl substitution degree of 2.86 was 80 parts by mass, and 20 parts by mass of polymer P-6 was further added. Thus, a monolayer film made of a mixture of P-6 and CA-1 was produced.

[Test Example 2: Interlayer adhesion test of laminate]
For the interlaminar adhesion of the laminate, a cross cut test according to JIS K 5400 was applied. The specific procedure is shown below.
Using a cutter knife and a cutter guide, 11 cuts with an interval of 1 mm were made on the surface on the polymer layer side of each laminate prepared above to produce 100 grids. After the cellophane tape was strongly pressure-bonded on the grid, the end of the tape was peeled off at an angle of 45 °, and the state of the grid (the state of peeling of the lattice constituting the grid) was observed. The observation results were evaluated by applying the following evaluation criteria.

(Interlayer adhesion evaluation criteria)
A: None of the lattice eyes peel off B: The lattice eye separation is less than 5% C: The lattice eye separation is 5% or more and less than 30% D: The lattice eye separation is 30% or more Certain results are shown in Table 2 below.

[Test Example 3: Durability test using change in haze value as an index]
Using a haze meter (HGM-2DP, Suga Tester), the haze value of the laminate or single layer film was measured according to JIS K-6714. Each laminate or single-layer film was cut into a size of 40 mm × 80 mm and measured under conditions of 25 ° C. and a relative humidity of 60% RH.
Moreover, after preserve | saving for 72 hours on the conditions of 105 degreeC and relative humidity 10% RH, the haze value was measured on the conditions similar to the above. Based on the obtained haze value, the amount of change in haze value was calculated from the following formula, and the durability of the laminate or single layer film was evaluated according to the following evaluation criteria.
Change in haze value (%) = haze value after storage (%)-haze value before storage (%)
(Durability evaluation criteria)
A: Change amount of haze value is less than 0.5% B: Change amount of haze value is 0.5% or more and less than 1% C: Change amount of haze value is 1% or more and less than 2% D: Change amount of haze value The results are shown in Table 2 below.

As shown in Table 2, when HP-1 was used for the polymer layer, the desired laminated structure could not be formed because of the low solubility of HP-1 (Comparative Example 2). In addition, when the polymer layer was formed using a polymer having no repeating unit of the general formula (1) and having a Tg lower than that defined in the present invention, the interlayer adhesion was good, but the durability test Later, the haze value increased significantly (Comparative Example 3).
On the other hand, all the laminates in which the polymer layer is formed using the polymer specified in the present invention have good interlayer adhesion and are within a practically acceptable range, and the haze value increases even after the durability test. Was well suppressed (Examples 1 to 10).

[Production Example 3: Production of polarizing plates PL-1 to PL-3 and comparative polarizing plate HPL-1]
The polarizing plates PL-1 to PL-3 and the comparative polarizing plate HPL-1 were produced as follows.
(1) Saponification Commercially available cellulose acylate film (Fujitack ZRD40, manufactured by Fuji Film Co., Ltd.), laminates S-1, S-5, S-8 and monolayer film HS-1 prepared above were After being immersed in a 1.5 mol / L NaOH aqueous solution (saponification solution) kept at ° C. for 2 minutes, the ZRD 40 and each laminate were washed with water. Next, after ZRD40 and each of the above laminates were immersed in a 0.05 mol / L sulfuric acid aqueous solution at 25 ° C. for 30 seconds, a water washing bath was further passed under running water for 30 seconds, and ZRD40, each laminate and single layer film were It was in a neutral state. The obtained ZRD40, each laminate and single-layer film were drained with an air knife three times, and after dropping water, it was retained in a drying zone at 70 ° C. for 15 seconds, dried, and saponified ZRD40, each laminate. And a single layer film was obtained.

(2) Production of Polarizer According to Example 1 of Japanese Patent Application Laid-Open No. 2001-141926, iodine was adsorbed to a stretched polyvinyl alcohol film to produce a polarizer having a thickness of 27 μm.

(3) Bonding Each laminated body after the above saponification (arranged so that the polymer layer side of each laminated body is in contact with the polarizer) or a single-layer film, the polarizer produced above, and the cell after the above saponification The roll acylate film ZRD40 was laminated with a PVA adhesive in this order and heat-dried to prepare polarizing plates PL-1 to PL-3 and a comparative polarizing plate HPL-1.
Under the present circumstances, it arrange | positioned so that the longitudinal direction of the roll of the produced polarizer and the longitudinal direction of the roll of the cellulose-ester resin layer of each laminated body or the longitudinal direction of the roll of a single layer film may become parallel. Moreover, it arrange | positioned so that the longitudinal direction of the roll of a polarizer and the longitudinal direction of the roll of the said cell roll acylate film ZRD40 may become parallel.

[Test Example 4: Evaluation of polarizer durability of polarizing plate]
The durability of the polarizing plate was measured by measuring the orthogonal transmittance and the polarization degree in the following manner in a form in which the polarizing plate was attached to glass through an adhesive.
A polarizing plate is placed on the glass plate so that the side of the laminates S-1, S-5, S-8 and the single layer film HS-1 is on the air interface side (so that it is on the side away from the glass plate). Two pasted samples (about 5 cm × 5 cm) were prepared. About these samples, the glass plate side was set toward the light source, and the degree of polarization was measured. Each of the two samples was measured and the arithmetic average value was taken as the polarization degree of the polarizing plate.
The degree of polarization was calculated by the following formula.

Polarization degree (%) = [(parallel transmittance−orthogonal transmittance) / (orthogonal transmittance + parallel transmittance)] ^1/2 × 100

The degree of polarization was measured in the range of 380 nm to 780 nm using an automatic polarizing film measuring device VAP-7070 manufactured by JASCO Corporation, and the measured value at a wavelength of 410 nm at which the degree of deterioration is more noticeable than other wavelengths was adopted. .
Thereafter, it was stored for 500 hours in an environment of a temperature of 85 ° C. and a relative humidity of 85%. Subsequently, the polarization degree was measured about two samples like the above, the measured value of two samples was arithmetically averaged, and it was set as the polarization degree of the polarizing plate after a preservation | save. Based on the amount of change in the degree of polarization before and after storage, the polarizing plate durability was evaluated based on the following evaluation criteria.
Here, the amount of change in polarization degree is calculated by the following equation.

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

<Polarizer durability evaluation criteria>
A: Polarization degree change amount is less than 0.05% B: Polarization degree change amount is 0.05% or more and less than 1.0% C: Polarization degree change amount is 1.0% or more and less than 2.0% D: Polarization degree Change amount is 2.0% or more and less than 3.0% E: Polarization degree change amount is 3.0% or more The results are shown in Table 3 below.

As described in Table 3 above, the polarizing plates PL-1 to PL-3 of the present invention using the laminate of the present invention as a protective film can be stored for a long time under severe conditions of high temperature and high humidity. The change in the degree of polarization could be kept as low as less than 3.0%, and excellent polarizer durability was exhibited. That is, by incorporating a polarizing plate using the laminate of the present invention as a protective film for a polarizer into an image display device, deterioration in image quality can be effectively suppressed even when used for a long time under high temperature and high humidity conditions. Recognize.

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. 2016-032780 filed in Japan on February 24, 2016, which is hereby incorporated herein by reference. Capture as part.

10 Laminate (laminate)
DESCRIPTION OF SYMBOLS 11 Cellulose ester resin layer 12 Polymer layer 20 Liquid crystal display device 21 Upper polarizing plate 22 Upper polarizing plate absorption axis direction 23 Liquid crystal cell upper electrode substrate 24 Liquid crystal layer 25 Liquid crystal cell lower electrode substrate 26 Lower polarizing plate 27 Lower polarizing plate absorption Axial direction

Claims (7)

1. A cellulose ester resin layer, and a layer containing a polymer having a repeating unit represented by the following general formula (1) provided directly on the cellulose ester resin layer, and the glass transition temperature of the polymer is 50 ° C. That is the laminate.
   

   

   In General Formula (1), R ^a represents a hydrogen atom, an alkyl group, or an alkoxycarbonyl group.
   R ^b and R ^c represent a hydrogen atom, an alkyl group, an aryl group or an alkoxycarbonyl group.
   R ² represents an alkyl group, a cycloalkyl group or an aryl group.
   L ¹ represents a divalent linking group formed by combining two or more divalent groups selected from an alkylene group, an arylene group, —C (═O) —, —O—, and —NR ³ —. However, L ¹ includes a group represented by —C (═O) NR ³ —.
   R ³ represents a hydrogen atom or a substituent.
2. The laminate according to claim 1, wherein the repeating unit represented by the general formula (1) is a repeating unit represented by the following general formula (2) or (3).
   

   

   In general formula (2), R ^1a represents a hydrogen atom or methyl.
   R ² has the same meaning as ^{R 2} in the general formula (1).
   L ² represents an alkylene group, an alkyleneoxy group or a polyalkyleneoxy group.
   A represents —C (═O) NR ³ — or —NR ³ —C (═O) —NR ³ —. R ³ has the same meaning as ^{R 3} in Formula (1).
   

   

   In the general formula ^{(3), R 1a} and ^{R 2} have the same meanings as ^{R 1a} and ^{R 2} in each of the general formula (2).
   R ^3a represents a hydrogen atom or an alkyl group.
3. The laminate according to claim 2, wherein the repeating unit represented by the general formula (3) is a repeating unit represented by the following general formula (4).
   

   

   In the general formula ^{(4), R 1a} and ^{R 2} have the same meanings as ^{R 1a} and ^{R 2} in each of the general formula (3).
4. The polymer having a repeating unit represented by the general formula (1) has a repeating unit represented by the general formula (1) and a repeating unit represented by the following general formula (5). 4. The laminate according to any one of 1 to 3.
   

   

   In General Formula (5), R ⁴ and R ⁵ represent a hydrogen atom, an alkyl group, an aryl group, or an alkoxycarbonyl group.
   R ⁶ represents a hydrogen atom or an alkyl group.
   L ³ is a single bond, a divalent group selected from an alkylene group, an arylene group, —C (═O) —, —O— and —N (R ^3A ) —, or two of these groups A divalent linking group formed by combining the above is shown.
   R ^3A represents a hydrogen atom or a substituent.
5. The laminate according to any one of claims 1 to 4, wherein the content of the polymer having the repeating unit represented by the general formula (1) in the laminate is 1 to 30% by mass.
6. A polarizing plate comprising the laminate according to any one of claims 1 to 5 and a polarizer.
7. An image display device having the polarizing plate according to claim 6.

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