WO2013115178A1

WO2013115178A1 - Polarizing plate and display device using same

Info

Publication number: WO2013115178A1
Application number: PCT/JP2013/051890
Authority: WO
Inventors: 隆建部; 矢野　健太郎
Original assignee: コニカミノルタ株式会社
Priority date: 2012-01-30
Filing date: 2013-01-29
Publication date: 2013-08-08
Also published as: KR20140125406A; JPWO2013115178A1; KR101634026B1

Abstract

[Problem] To provide a polarizing plate capable of minimizing the occurrence of color inconsistency in a display device when used as a panel display. [Solution] In a polarizing plate which is formed by stretch processing a laminated body of a hydrophilic polymer layer and a basic material including a thermoplastic resin and has a stretched laminated body wherein a dichroic material is adsorbed onto said hydrophilic polymer layer, the curl fluctuation under two environments where temperature and humidity are different is controlled to be a prescribed value or less.

Description

Polarizing plate and display device using the same

The present invention relates to a polarizing plate and a display device using the same.

In recent years, technological innovation in the field of display devices has been remarkable, and development of display devices such as liquid crystal display devices and organic EL display devices has been promoted, and many products have been put on the market.

As a method of the liquid crystal display device, commonly known as TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type and the like are well known. The liquid crystal display device usually includes a liquid crystal cell having a liquid crystal layer and a pair of substrates sandwiching the liquid crystal layer, and polarizing plates respectively disposed on both sides (viewing side and backlight side) of the liquid crystal cell. is there. In particular, IPS (In-Plane Switching) mode type liquid crystal display devices (hereinafter, also simply referred to as “IPS type liquid crystal display devices”) are widely used in portable devices such as tablet display devices and smartphones. It has been. In the IPS liquid crystal display device, the liquid crystal molecules contained in the liquid crystal layer are aligned in parallel to the surfaces of the pair of substrates during black display, and thus the IPS liquid crystal display device has an advantage of excellent black display performance. Further, the IPS liquid crystal display device has an advantage that a certain high viewing angle can be secured without using a so-called optical compensation film (viewing angle widening film). On the other hand, due to the optical characteristics of the liquid crystal cell provided in the IPS liquid crystal display device, there is a problem that light leakage occurs when the screen is viewed from an oblique direction, and the contrast of the display image is lowered.

In general, a retardation film is used in a liquid crystal display device for the purpose of preventing such a decrease in contrast. However, in order to further improve the performance, a retardation film capable of supporting various optical designs is required. It is getting to be. In addition, regarding the retardation film mounted on the portable device as described above, there is a strong demand for further reduction in thickness and weight.

One of the important components of liquid crystal display devices is a polarizing plate. The polarizing plate has a configuration in which a polarizer and a polarizing plate protective film for protecting the polarizer are laminated. A so-called coating type polarizing plate is known as one type of polarizing plate, but this coating type polarizing plate has a problem that curling occurs in a humidified environment. When curling occurs in the polarizing plate, display unevenness (color unevenness) locally occurs when the display device is configured.

Conventionally, when the coating type polarizing plate is thinned, the hydrophilicity of the stretched laminate obtained by stretching the laminate of the base material layer and the hydrophilic polymer layer is a technique capable of preventing the occurrence of curling even in a humidified environment. A technique has been proposed in which a dichroic substance adsorbed on a functional polymer layer is used as a polarizing plate (see Patent Document 1). Here, in patent document 1, polyolefin resin, cyclic polyolefin resin, and (meth) acrylic resin are illustrated as a preferable material which comprises a base material layer. And in the Example of patent document 1, the example which used the acrylic resin film (lactone-ized polymethylmethacrylate film) and the norbornene-type resin film as a base material layer is disclosed.

US Patent Application Publication No. 2010/0202051

The present inventors examined the technique described in Patent Document 1 described above. As a result, it has been found that even when the polarizing plate is configured by the technique described in Patent Document 1, display unevenness (color unevenness) may occur when the display device is still configured.

Therefore, an object of the present invention is to provide a polarizing plate that can suppress the occurrence of color unevenness when a display device displays a panel.

The present inventors have conducted intensive studies in view of the above problems. As a result, a polarizing plate having a stretched laminate in which a laminate of a hydrophilic polymer layer and a base material layer containing a thermoplastic resin is stretched and a dichroic substance is adsorbed on the hydrophilic polymer layer. The inventors have found that the above problem can be solved by controlling the fluctuation of the curl in two environments having different temperatures and humidity to be a predetermined value or less, and have completed the present invention.

That is, the above object of the present invention is achieved by the following configuration.

1. A polarizing plate having a stretched laminate in which a laminate of a hydrophilic polymer layer and a base material layer containing a thermoplastic resin is stretched, and a dichroic substance is adsorbed on the hydrophilic polymer layer, ,
The difference ΔC = | C ₁ −C ₂ | between the curl C ₁ in the environment of 23 ° C. and 55% RH and the curl C ₂ in the environment of 40 ° C. and 20% RH satisfies ΔC ≦ 80 [1 / m]. ,Polarizer;
2. 2. The polarizing plate according to 1 above, wherein the base material layer contains at least two thermoplastic resins;
3. 3. The polarizing plate according to 1 or 2 above, wherein the hydrophilic polymer layer has a thickness of 0.5 to 30 μm;
4). Any of the above 1 to 3, wherein the thermoplastic resin contained in the base material layer comprises an acrylic resin, a styrene resin, a cycloolefin resin, a cellulose resin, a polypropylene resin, a polyester resin, or a combination thereof. Or a polarizing plate according to claim 1;
5. The base material layer is at least
A first base material layer containing a first thermoplastic resin;
A second substrate layer comprising a second thermoplastic resin, disposed on the opposite side of the hydrophilic polymer layer with respect to the first substrate layer;
5. The polarizing plate according to any one of the above 1 to 4, which has

6). The difference ΔE = | Ea−Eb | (MPa) between the elastic modulus Ea of the first base material layer and the elastic modulus Eb of the second base material layer satisfies ΔE ≦ 3000 [MPa], and
Differences ΔEa = | Ea ₁ −Ea ₂ | and ΔEb between the elastic moduli Ea ₁ and Eb _{1 in a} 23 ° C. and 55% RH environment and the elastic moduli Ea ₂ and Eb _{2 in} a 40 ° C. and 20% RH environment, respectively. == Eb ₁ −Eb ₂ | satisfying ΔEa, ΔEb ≦ 2000 [MPa];
7). 7. The polarizing plate according to any one of 1 to 6, wherein the stretched laminate has a thickness of 10 to 100 μm;
8). The polarizing plate according to any one of 1 to 7 above, wherein the hydrophilic polymer layer contains polyvinyl alcohol as a hydrophilic polymer;
9. The polarizing plate according to any one of 1 to 8, wherein the dichroic substance is iodine;
10. 10. A method for producing a polarizing plate according to any one of 1 to 9 above,
A production method comprising a step of forming the substrate layer by a solution casting method;
11. 11. The production method according to 10 above, further comprising a step of applying a solution containing a hydrophilic polymer to one surface of the base material layer formed and drying to obtain a laminate.
12 The production method according to the above 11, further comprising a step of stretching the laminate at a stretching ratio of 2 to 10 times;
13. 10. A display device comprising the polarizing plate according to any one of 1 to 9 or the polarizing plate produced by the production method according to any one of 10 to 12;
14 14. The display device according to the above 13, which is an IPS mode type liquid crystal display device.

Hereinafter, embodiments of the present invention will be described in detail.

≪Polarizing plate≫
One embodiment of the present invention is a polarizing plate having a stretched laminate in which a laminate of a hydrophilic polymer layer and a thermoplastic resin layer is stretched, and a dichroic substance is adsorbed on the hydrophilic polymer layer. About. The polarizing plate according to this embodiment has a difference ΔC = | C ₁ −C ₂ | between the curl C ₁ in the environment of 23 ° C. and 55% RH and the curl C ₂ in the environment of 20 ° C. and 20% RH. It is characterized in that ΔC ≦ 80 [1 / m] is satisfied. ADVANTAGE OF THE INVENTION According to this invention, the polarizing plate which can suppress generation | occurrence | production of the color nonuniformity at the time of panel display of a display apparatus is provided.

As described above, the polarizing plate according to the present embodiment is obtained by stretching a laminate of a hydrophilic polymer layer and a thermoplastic resin layer and adsorbing a dichroic substance on the hydrophilic polymer layer. It has a laminate. Hereinafter, the constituent elements of the stretched laminate will be described in more detail.

[Hydrophilic polymer layer]
The stretched laminate is first provided with a hydrophilic polymer layer. The hydrophilic polymer layer is a layer containing a hydrophilic polymer as a main component. And in the polarizing plate which concerns on this form, a hydrophilic polymer layer adsorb | sucks a dichroic substance. Thereby, the hydrophilic polymer layer functions as a polarizer in the polarizing plate according to the present embodiment.

Although there is no restriction | limiting in particular about the hydrophilic polymer which comprises a hydrophilic polymer layer, A polyvinyl alcohol-type material is illustrated preferably. Examples of the polyvinyl alcohol material include polyvinyl alcohol and derivatives thereof. Derivatives of polyvinyl alcohol include polyvinyl formal, polyvinyl acetal and the like, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, alkyl esters thereof, acrylamide and the like. Can be mentioned. The degree of polymerization of polyvinyl alcohol is preferably about 100 to 10,000, and more preferably 1,000 to 10,000. A saponification degree of about 80 to 100 mol% is generally used. In addition to the above, examples of the hydrophilic polymer include partially saponified ethylene / vinyl acetate copolymer, dehydrated polyvinyl alcohol and dehydrochlorinated polyvinyl chloride. As the hydrophilic polymer, it is preferable to use polyvinyl alcohol among polyvinyl alcohol materials.

The hydrophilic polymer layer may contain additives such as a plasticizer and a surfactant in addition to the hydrophilic polymer described above. Examples of the plasticizer include polyols and condensates thereof, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of the plasticizer used is not particularly limited, but it is preferably 20% by mass or less with respect to 100% by mass of the total amount of the hydrophilic polymer layer.

The specific configuration of the dichroic substance adsorbed on the hydrophilic polymer layer is not particularly limited, and examples thereof include iodine and organic dyes. Organic dyes include, for example, Red BR, Red LR, Red R, Pink LB, Rubin BL, Bordeaux GS, Sky Blue LG, Lemon Yellow, Blue BR, Blue 2R, Navy RY, Green LG, Violet LB, Violet B, Black H, Black B, Black GSP, Yellow 3G, Yellow R, Orange LR, Orange 3R, Scarlet GL, Scarlet KGL, Congo Red, Brilliant Violet BK, Spura Blue G, Spura Blue GL, Spura Orange GL, Direct Sky Blue, Direct First orange S, first black, etc. can be used. Of these, iodine is preferably used as the dichroic material from the viewpoint of water solubility and process suitability. As for these dichroic substances, only 1 type may be used independently and 2 or more types may be used together.

The amount of dichroic substance adsorbed in the hydrophilic polymer layer is not particularly limited, and can be set as appropriate with reference to known knowledge.

The thickness of the hydrophilic polymer layer after stretching is not particularly limited, but is preferably 0.5 to 30 μm, more preferably 1 to 10 μm. If the thickness is a value equal to or greater than the lower limit, there is an advantage that the influence of thickness variation during manufacturing is reduced and appearance defects are less likely to occur. On the other hand, if the thickness is a value equal to or less than the upper limit, there is an advantage that the drying property of the aqueous solution is improved and the productivity is improved. In addition, as the value of the thickness of the hydrophilic polymer layer, a value measured by a method of subtracting the thickness of the film obtained by stretching only the base film under the same conditions from the thickness of the stretched laminate is adopted. The thickness is measured using a film thickness meter or the like.

[Base material layer]
The stretched laminate also includes a substrate layer. The base material layer can function as a base material for preparing the hydrophilic polymer layer when the stretched laminate (polarizing plate) is prepared. Moreover, a base material layer functions as a protective layer (protective film) for protecting a polarizer in the polarizing plate which concerns on this form. In addition, you may provide another layer as needed between a base material layer and a hydrophilic polymer layer.

The base material layer includes a thermoplastic resin. There is no restriction | limiting in particular about the thermoplastic resin contained in a base material layer, Any thing can be used if it is the material which can achieve (DELTA) C of the polarizing plate mentioned above. Preferably, the base material layer is composed of a stretchable thermoplastic resin. Examples of stretchable thermoplastic resins include acrylic resins, styrene resins, cycloolefin resins, cellulose resins, polypropylene resins, polyester resins, or combinations thereof. In this case, as the acrylic resin, an acrylic resin containing a structural unit derived from methyl methacrylate as a main component and further comprising a structural unit derived from a monomer component copolymerizable therewith is preferably used. The copolymerizable monomer component also includes an acrylic acid derivative having a ring structure. Examples of the styrenic resin include a styrenic resin containing a structural unit derived from styrene as a main component and further containing a structural unit derived from a monomer component copolymerizable therewith. Furthermore, examples of the cycloolefin resin include a norbornene resin called a cycloolefin polymer. In addition to polypropylene, examples of the polypropylene-based resin include polypropylene partially containing polyethylene, and examples of the polyester-based resin include polyethylene terephthalate (PET).

Among these, in a preferred embodiment, the base material layer contains a cellulosic resin. Although there is no restriction | limiting in particular also about the specific form of cellulose resin, Cellulose resin polymerized in presence of cellulose ester, cellulose ether, cationized cellulose, various vinyl monomers, various vinyl monomers, etc. A graft polymer or the like is used. Of these, cellulose ester resins are particularly preferably used.

The specific form of the cellulose ester resin is not particularly limited, but in particular from the viewpoint of improving brittleness and transparency, the following formulas (1) to (3):

In the formula, A represents the degree of substitution of the acetyl group, and B represents the sum of the degree of substitution of the acyl group having 3 to 7 carbon atoms.
It is preferable to have an acyl group substitution degree that satisfies the above relationship.

If the total substitution degree (A + B) of the acyl group having 2 to 7 carbon atoms of the cellulose ester resin is 2.0 or more (that is, the residual degree of hydroxyl groups at the 2, 3, 6 positions of the cellulose ester molecule is 1.0 or less If the substrate layer functions as a polarizing plate protective film, an increase in haze is prevented. If the total acyl group substitution degree (A + B) is 2.0 or more and the substitution degree of the acyl group having 3 to 7 carbon atoms is 1.0 or more, the brittleness is prevented from being lowered.

The cellulose ester resin has an acyl group substitution degree of 2.0 to 3.0 in total substitution degree (A), 0.15 to 2.0 substitution degree of acetyl group (A), and 3 carbon atoms. There is no problem if the substitution degree (B) of the acyl group of 7 to 1.2 is 1.2 to 3.0, but an acyl group other than 3 to 7 carbon atoms, that is, an acetyl group or an acyl group having 8 or more carbon atoms It is preferable that the total degree of substitution is 1.3 or less. Further, the total substitution degree (A + B) of the acyl group having 2 to 7 carbon atoms of the cellulose ester resin is more preferably in the range of 2.5 to 3.0.

The acyl group may be an aliphatic acyl group or an aromatic acyl group. In the case of an aliphatic acyl group, it may be linear or branched and may further have a substituent. The number of carbon atoms of the acyl group in the present invention includes an acyl group substituent.

When the cellulose ester resin has an aromatic acyl group as a substituent, the number of substituents X substituted on the aromatic ring is preferably 0 to 5. In this case as well, in the above-described preferred embodiment, attention should be paid so that the substitution degree of the acyl group having 3 to 7 carbon atoms including the substituent is 1.0 to 2.75. For example, since the benzoyl group has 7 carbon atoms, when it has a substituent containing carbon, the benzoyl group has 8 or more carbon atoms and is not included in the acyl group having 3 to 7 carbon atoms. Become.

Further, when the number of substituents substituted on the aromatic ring is 2 or more, these may be the same or different from each other, and are connected to each other to form a condensed polycyclic compound (for example, naphthalene, indene, indane, phenanthrene, Quinoline, isoquinoline, chromene, chromane, phthalazine, acridine, indole, indoline, etc.).

The cellulose ester resin is preferably at least one selected from cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose propionate, and cellulose butyrate. Among these, cellulose ester resins that are particularly preferred are cellulose acetate propionate and cellulose propionate. In the present invention, two or more kinds of cellulose ester resins can be mixed and used.

The portion not substituted with an acyl group is usually present as a hydroxyl group. These can be synthesized by known methods. Further, the substitution degree of acetyl group and the substitution degree of other acyl groups are determined by the method prescribed in ASTM-D817-96.

The weight average molecular weight (Mw) of the cellulose ester resin is preferably 75,000 or more, more preferably in the range of 75,000 to 300,000, and still more preferably in the range of 100,000 to 24,000, particularly from the viewpoint of improving brittleness. 160000-240000 are particularly preferred. When the weight average molecular weight (Mw) of the cellulose ester resin is less than 75,000, the heat resistance and brittleness improvement effects may not be sufficiently obtained.

The thickness of the base material layer constituting the stretched laminate is not particularly limited, but is preferably 10 to 200 μm, and more preferably 20 to 80 μm. If the said thickness is more than a lower limit, the intensity | strength as a polarizing plate is fully ensured. On the other hand, when the thickness is equal to or less than the upper limit value, the occurrence of curling of the polarizing plate can be further prevented. In addition, as the value of the thickness of the base material layer, a value obtained by preparing a film obtained by stretching only the base material film under the same conditions and measuring the thickness is adopted.

The water absorption when the base material layer is impregnated in 23 ° C. water for 24 hours is preferably 1.0 to 8.0 mass%. The water absorption rate is preferably 2.0 to 5.0% by mass, more preferably 3.0 to 5.0% by mass. In addition, the value measured with the following method shall be employ | adopted as a value of the water absorption rate of a base material layer.

(Measurement method of water absorption rate of base material layer)
Only the base material layer is separated from the stretched laminate, impregnated in water at 23 ° C. for 24 hours, and then pulled up from the water to measure the mass (M1) of the base material layer. Then, after leaving still with respect to a base material layer at 23 degreeC55% RH for 24 hours, the mass (M0) of a base material layer is measured. From these measurement results, the water absorption is calculated according to the following mathematical formula (4).

Constructing a stretched laminate with a hydrophilic polymer layer using a base material layer having a water absorption rate satisfying the above-mentioned regulations, and using this as a polarizing plate will cause display unevenness during panel display of a display device Can be more reliably suppressed.

Although there is no restriction | limiting in particular about the specific form of a cellulose ether resin, It has an ether bond in the at least 1 substituent of the 2, 3, 6 position in a cellulose molecule. The ether bond referred to here is a carbon-oxygen-carbon bond. Examples of the cellulose ether include, but are not limited to, methyl cellulose, ethyl cellulose, carboxymethyl cellulose, carboxymethyl ethyl cellulose, hydroxyethyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, and the like. Further, ethyl cellulose is optimal for ensuring transparency and durability as an optical film. The degree of ethoxyl substitution is preferably in the range of 1.9 to 2.9, and in the range of 2.2 to 2.9 from the balance between the viscosity at the time of melting and the stability of the moist heat resistant environment. Particularly preferred. The degree of ether substitution can be quantified by the method described in ASTM D4794-94. The molecular weight of the cellulose ether only needs to be able to be formed into a film alone. Specifically, the number average molecular weight Mn may be in the range of 30,000 ≦ Mn ≦ 300,000 (polystyrene conversion). Preferably, 50,000 to 200,000 are used. If the molecular weight is too small, the film becomes fragile, and if the molecular weight is too high, the viscosity is high and the molding stability at the time of molding processing is deteriorated, which is not preferable for production.

In a preferred embodiment of the present invention, the base material layer includes at least two kinds of thermoplastic resins. In such an embodiment, it is preferable that at least two types of thermoplastic resins included in the base material layer include a cellulose ester resin and an acrylic resin as essential components, and only these two types are included as the thermoplastic resin. It is particularly preferred.

As a form in which a base material layer contains two or more kinds of thermoplastic resins, (i) a form in which two or more kinds of thermoplastic resins constitute a single base material layer having a uniform composition as a mixture in a compatible state, ii) A mode in which two or more base material layers containing different thermoplastic resins as a main ingredient are laminated to form a base material layer, (iii) a mode in which these (i) and (ii) are combined, and the like are exemplified.

Examples of the form (i) include a form in which a cellulose ester resin and an acrylic resin are included in a compatible state. About such a form, the disclosure content etc. of the international publication 2011/121720 pamphlet and the international publication 2011/121817 pamphlet can be referred.

Moreover, there is no restriction | limiting in particular also about the form of (ii), The base material layer containing one of the thermoplastic resins mentioned above and the base material layer containing the thermoplastic resin different from the said thermoplastic resin are laminated | stacked. Any form can be adopted. However, from the viewpoint of ensuring adhesion with the hydrophilic polymer layer, among the laminated base materials having different compositions, the base material layer located on the hydrophilic polymer layer side (in the present specification, A substrate layer (also referred to as “first substrate layer”) containing a cellulose-based resin (preferably a cellulose ester resin) and located on the side opposite to the hydrophilic polymer layer (in the present specification, “ It is preferable that the second base layer ”also includes an acrylic resin.

Furthermore, as a preferred embodiment, the difference ΔE = | Ea−Eb | (MPa) between the elastic modulus Ea of the first base material layer and the elastic modulus Eb of the second base material layer is ΔE ≦ 3000 [MPa]. Is preferably satisfied, ΔE ≦ 2500 is more preferably satisfied, and ΔE ≦ 2000 is further preferably satisfied. In addition, the elastic moduli Ea and Eb in the environment of 23 ° C. and 55% RH are Ea ₁ and Eb ₁ , respectively, and the elastic moduli Ea and Eb in the environment of 40 ° C. and 20% RH are Ea ₂ and Eb ₂ , respectively. , Ea and Eb, ΔEa = | Ea ₁ −Ea ₂ | and ΔEb = | Eb ₁ −Eb ₂ | preferably satisfy ΔEa, ΔEb ≦ 2000 [MPa], and satisfy ΔEa, ΔEb ≦ 1500. It is more preferable that ΔEb ≦ 1000 is satisfied. It is also a more preferable embodiment to satisfy both the preferable definition of ΔE and the preferable specifications of ΔEa and ΔEb. In addition, the value measured with the method as described in the column of the Example mentioned later as a value of the elasticity modulus of a 1st base material layer and a 2nd base material layer shall be employ | adopted. Moreover, in order to control the value of the elastic modulus of the first base material layer and the second base material layer, at the time of producing the base material layer, the draw ratio, the stretch speed, the temperature at the time of stretching, the humidity at the time of stretching, etc. May be adjusted as appropriate.

The base material layer may contain various additives in addition to the above-described thermoplastic resin.

<Low molecular weight acrylic polymer>
Examples of the additive that can be added to the base material layer include a low molecular weight acrylic polymer. The weight average molecular weight (Mw) of the low molecular weight acrylic polymer is preferably 500 to 30000. Among the low molecular weight acrylic polymers, a polymer X ₁ having a weight average molecular weight of 500 to 30,000 obtained by polymerizing an ethylenically unsaturated monomer Xa having no aromatic ring and no hydrophilic group in the molecule, or an aromatic ring in the molecule And an ethylenically unsaturated monomer Xa having no hydrophilic group and an ethylenically unsaturated monomer Xb having no hydrophilic ring in the molecule and having a hydrophilic group, having a weight average molecular weight of 500 to 30,000 preferably contains a polymer X _2. Here, examples of the ethylenically unsaturated monomer Xa having no aromatic ring and no hydrophilic group in the molecule include (meth) acrylic acid esters as described later, and methyl methacrylate (MMA) is particularly preferable. Examples of the ethylenically unsaturated monomer Xb having no hydrophilic ring in the molecule and having a hydrophilic group include acryloylmorpholine, vinyl pyrrolidone, and hydroxyethyl methacrylate. The content ratio of the structural unit derived from Xa and the structural unit derived from Xb in X ₂ is not particularly limited, but the mass ratio of the structural unit derived from Xa to the structural unit derived from Xb is preferably 50:50 to 95: 5. 60:40 to 90:10 is more preferable, and 70:30 to 80:20 is particularly preferable.

In addition, the weight average molecular weight of the above-mentioned acrylic polymer is preferably 1500 to 20000, more preferably 2000 to 10000, and particularly preferably 2500 to 5000. If the weight average molecular weight of the acrylic polymer is within such a range, there is an advantage that a balance between volatility and compatibility can be easily obtained.

Further, the content of the acrylic polymer in the base material layer is preferably 10 to 40% by mass, more preferably 20 to 30% by mass with respect to 100% by mass of the thermoplastic resin. In addition, when a base material layer consists of a laminated body of a several base material layer, the value of this content is a mass ratio with respect to the total amount of the thermoplastic resin which comprises the base material layer in which the said additive is contained (hereinafter the same). ).

Examples of additives other than the low molecular weight acrylic polymer include plasticizers, sugar ester compounds, retardation adjusting agents, and coloring agents.

<Plasticizer>
Although there is no restriction | limiting in particular about the specific form of a plasticizer, For example, a polyester plasticizer is mentioned. There is no restriction | limiting in particular about the specific structure of a polyester plasticizer, The polyester plasticizer which has an aromatic ring or a cycloalkyl ring in a molecule | numerator can be used. As a polyester plasticizer, the polyester compound represented by following General formula (4) is mentioned, for example.

The polyester compound represented by these is mentioned.

In the general formula (4), B represents a linear or branched alkylene group or cycloalkylene group having 2 to 6 carbon atoms, and A represents an aromatic ring having 6 to 14 carbon atoms or a C 2 to 6 carbon atoms. A linear or branched alkylene group or a cycloalkylene group is represented, X represents a monocarboxylic acid residue containing a hydrogen atom or an aromatic ring having 6 to 14 carbon atoms, and n represents a natural number of 1 or more.

The polyester compound represented by the general formula (4) includes a dicarboxylic acid having an aromatic ring (having 6 to 14 carbon atoms) or a linear or branched alkylene group or cycloalkylene group (both having 2 to 6 carbon atoms) and a carbon number. An alternating copolymer obtained by alternating copolymerization with 2 to 6 linear or branched alkylene diols or cycloalkylene diols. The aromatic dicarboxylic acid and the dicarboxylic acid having a linear or branched alkylene group or cycloalkylene group may be used alone or as a mixture, but the main component constituting the polarizing plate protective film may be used. In view of compatibility with a resin (for example, a cellulose ester resin), it is preferable that at least 10% of an aromatic dicarboxylic acid is contained. Alternatively, both ends may be sealed with a monocarboxylic acid having an aromatic ring (having 6 to 14 carbon atoms).

Examples of dicarboxylic acids having an aromatic ring (6 to 14 carbon atoms), that is, aromatic dicarboxylic acids having 6 to 16 carbon atoms include phthalic acid, isophthalic acid, terephthalic acid, 1,5-naphthalenedicarboxylic acid, 1, 4-naphthalenedicarboxylic acid, 1,8-naphthalenedicarboxylic acid, 2,3-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, 2,8-naphthalenedicarboxylic acid, 2,2′-biphenyldicarboxylic acid, 4,4 And '-biphenyldicarboxylic acid. Among these, terephthalic acid, 2,6-naphthalenedicarboxylic acid, and 4,4'-biphenyldicarboxylic acid are preferable.

Examples of the dicarboxylic acid having a linear or branched alkylene group or cycloalkylene group (2 to 6 carbon atoms) include malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, and 1,2-cyclohexane. Examples thereof include dicarboxylic acid and 1,4-cyclohexanedicarboxylic acid. Of these, succinic acid, adipic acid, and 1,4-cyclohexanedicarboxylic acid are preferable.

Examples of the linear or branched alkylene diol or cycloalkylene diol having 2 to 6 carbon atoms include ethanediol (ethylene glycol), 1,2-propanediol, 1,3-propanediol, 1,2- Butanediol, 1,3-butanediol, 2-methyl-1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6- Examples include hexanediol, 1,4-cyclohexanediol, and 1,4-cyclohexanedimethanol. Among these, ethanediol (ethylene glycol), 1,2-propanediol, 1,3-propanediol, and 1,3-butanediol are preferable.

Among these, A is preferably a benzene ring, naphthalene ring or biphenyl ring which may have a substituent, from the viewpoint of excellent plasticity imparting performance. Here, the “substituent” that the benzene ring, naphthalene ring or biphenyl ring may have is an alkyl group having 1 to 6 carbon atoms, an alkenyl group having 2 to 6 carbon atoms, or an alkoxy group having 1 to 6 carbon atoms. is there.

Examples of the monocarboxylic acid having an aromatic ring (having 6 to 14 carbon atoms) that seals both ends of the polyester compound include benzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, p-tert-butylbenzoic acid, and dimethylbenzoic acid. Examples include acids and paramethoxybenzoic acid. Of these, benzoic acid, p-toluic acid and p-tert-butylbenzoic acid are preferred.

Aromatic polyester compounds can be prepared by the conventional methods, such as the above-mentioned hot-melt condensation method by the polyesterification reaction or transesterification reaction between the dicarboxylic acid and alkylene diol or cycloalkylene diol, or the interfacial condensation method between acid chlorides of these acids and glycols. It can be easily synthesized by either method. Furthermore, by adding the above-described aromatic monocarboxylic acid, a polyester compound in which both ends are sealed can be synthesized.

Examples of aromatic polyester compounds that can be used in the present invention are shown below.

The base material layer can further contain a plasticizer other than the polyester compound represented by the general formula (4).

Although it does not specifically limit as plasticizers other than the polyester compound represented by General formula (4), Preferably, polyhydric carboxylic acid ester plasticizer, glycolate type plasticizer, phthalate ester type plasticizer, fatty acid ester type It is selected from plasticizers and polyhydric alcohol ester plasticizers, ester plasticizers, acrylic plasticizers and the like.

Of these, when two or more plasticizers are used, at least one is preferably a polyhydric alcohol ester plasticizer.

The polyhydric alcohol ester plasticizer is a plasticizer composed of an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. A divalent to 20-valent aliphatic polyhydric alcohol ester is preferred.

The polyhydric alcohol preferably used in the present invention is represented by the following general formula (a).

(In the formula, R ₁₁ represents an n-valent organic group, n represents a positive integer of 2 or more, and the OH group represents an alcoholic and / or phenolic hydroxy group (hydroxyl group).

Examples of preferable polyhydric alcohols include the following, but are not limited thereto.

Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3- Butanediol, 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, galactitol, mannitol, 3-methylpentane Examples include 1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, and xylitol.

In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable.

There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention.

Examples of preferable monocarboxylic acids include the following, but are not limited thereto.

As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. The number of carbon atoms is more preferably 1-20, and particularly preferably 1-10. The inclusion of acetic acid is preferred because the compatibility with cellulose acetate increases, and it is also preferred to use a mixture of acetic acid and other monocarboxylic acids.

Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanoic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

Examples of preferable alicyclic monocarboxylic acids include cyclopentane carboxylic acid, cyclohexane carboxylic acid, cyclooctane carboxylic acid, and derivatives thereof.

Examples of preferred aromatic monocarboxylic acids include those in which 1 to 3 alkoxy groups such as alkyl group, methoxy group or ethoxy group are introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, biphenylcarboxylic acid, Examples thereof include aromatic monocarboxylic acids having two or more benzene rings such as naphthalenecarboxylic acid and tetralincarboxylic acid, or derivatives thereof. Benzoic acid is particularly preferable.

The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably 300 to 1500, and more preferably 350 to 750. A higher molecular weight is preferred because it is less likely to volatilize, and a smaller one is preferred in terms of moisture permeability and compatibility with cellulose acetate.

The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified, or a part of the OH groups may be left as they are.

The following are specific compounds of polyhydric alcohol esters.

The glycolate plasticizer is not particularly limited, but alkylphthalylalkyl glycolates can be preferably used.

Examples of alkyl phthalyl alkyl glycolates include methyl phthalyl methyl glycolate, ethyl phthalyl ethyl glycolate, propyl phthalyl propyl glycolate, butyl phthalyl butyl glycolate, octyl phthalyl octyl glycolate, methyl phthalyl ethyl Glycolate, ethyl phthalyl methyl glycolate, ethyl phthalyl propyl glycolate, methyl phthalyl butyl glycolate, ethyl phthalyl butyl glycolate, butyl phthalyl methyl glycolate, butyl phthalyl ethyl glycolate, propyl phthalyl butyl glycol Butyl phthalyl propyl glycolate, methyl phthalyl octyl glycolate, ethyl phthalyl octyl glycolate, octyl phthalyl methyl glycolate, octyl phthalate Ethyl glycolate, and the like.

Examples of the phthalate ester plasticizer include diethyl phthalate, dimethoxyethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, dioctyl phthalate, dicyclohexyl phthalate, and dicyclohexyl terephthalate.

Examples of the citrate plasticizer include acetyltrimethyl citrate, acetyltriethyl citrate, and acetyltributyl citrate.

Examples of fatty acid ester plasticizers include butyl oleate, methylacetyl ricinoleate, and dibutyl sebacate.

Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate, and the like.

The polyvalent carboxylic acid ester compound is composed of an ester of a divalent or higher, preferably a divalent to 20valent polyvalent carboxylic acid and an alcohol. The aliphatic polyvalent carboxylic acid is preferably divalent to 20-valent, and in the case of an aromatic polyvalent carboxylic acid or alicyclic polyvalent carboxylic acid, it is preferably trivalent to 20-valent.

The polyvalent carboxylic acid is represented by the following general formula (b).

In the formula, R ₁₂ represents an (m1 + n1) -valent organic group, m1 represents a positive integer of 2 or more, n1 represents an integer of 0 or more, a COOH group represents a carboxy group, and an OH group represents an alcoholic or phenolic hydroxy group.

Examples of preferable polyvalent carboxylic acids include, but are not limited to, the following.

Trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid, maleic acid, tetrahydrophthal An aliphatic polyvalent carboxylic acid such as an acid, an oxypolyvalent carboxylic acid such as tartaric acid, tartronic acid, malic acid and citric acid can be preferably used. In particular, it is preferable to use an oxypolycarboxylic acid from the viewpoint of improving retention.

The alcohol used in the polyvalent carboxylic acid ester compound that can be used in the present invention is not particularly limited, and known alcohols and phenols can be used.

For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms.

Also, alicyclic alcohols such as cyclopentanol and cyclohexanol or derivatives thereof, aromatic alcohols such as benzyl alcohol and cinnamyl alcohol, or derivatives thereof can be preferably used.

When an oxypolycarboxylic acid is used as the polycarboxylic acid, the alcoholic or phenolic hydroxy group (hydroxyl group) of the oxypolycarboxylic acid may be esterified with a monocarboxylic acid. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto.

As the aliphatic monocarboxylic acid, a straight-chain or side-chain fatty acid having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1 to 20 carbon atoms, and particularly preferably 1 to 10 carbon atoms.

Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid, olein Examples thereof include unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. The aromatic monocarboxylic acid which has, or those derivatives can be mentioned. Particularly preferred are acetic acid, propionic acid, and benzoic acid.

The molecular weight of the polyvalent carboxylic acid ester compound is not particularly limited, but is preferably in the range of 300 to 1000, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improving the retention, and the smaller one is preferable in terms of moisture permeability and compatibility with the cellulose resin.

The alcohol used for the polyvalent carboxylic acid ester that can be used in the present invention may be one kind or a mixture of two or more kinds.

The acid value of the polyvalent carboxylic acid ester compound that can be used in the present invention is preferably 1 mgKOH / g or less, and more preferably 0.2 mgKOH / g or less. Setting the acid value in the above range is preferable because the environmental fluctuation of the retardation is also suppressed.

The acid value refers to the number of milligrams of potassium hydroxide necessary for neutralizing the acid (carboxy group present in the sample) contained in 1 g of the sample. The acid value is measured according to JIS K0070.

Examples of particularly preferred polyvalent carboxylic acid ester compounds are shown below, but the present invention is not limited thereto.

For example, triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate, dibutyl tartrate, diacetyl dibutyl tartrate, Examples include tributyl trimellitic acid and tetrabutyl pyromellitic acid.

The plasticizer is preferably contained in an amount of 0.1 to 30% by mass, more preferably 2 to 20% by mass with respect to 100% by mass of the total amount of the base material layer.

<Sugar ester compound>
Since the base material layer further contains a sugar ester compound, hydrolysis of the cellulose ester resin is prevented, so that the water resistance of the film can be improved.

As an example of a sugar ester compound, the following general formula (5):

The compound represented by these is mentioned.

In the general formula (5), Q represents a monosaccharide or disaccharide residue, R represents an aliphatic group or an aromatic group, and m is bonded directly to the monosaccharide or disaccharide residue. 1 is the total number of — (O—C (═O) —R) groups directly bonded to monosaccharide or disaccharide residues, and 3 ≦ m + 1 ≦ 8 and l ≠ 0.

The compound having the structure represented by the general formula (5) is a single type of compound in which the number of hydroxyl groups (m) and the number of-(O—C (═O) —R) groups (1) are fixed. It is difficult to separate, and it is known that a compound in which several components different in m and l in the formula are mixed is obtained. Therefore, the performance as a mixture in which the number of hydroxyl groups (m) and the number of-(OC (= O) -R) groups (l) are changed is important. The cellulose acylate film of this embodiment In this case, a compound having a structure represented by the general formula (5) with respect to haze characteristics and a mixing ratio of the component m = 0 and the component m> 0 is 45:55 to 0: 100 is preferable. More preferably, in terms of performance and cost, the mixing ratio of the component m = 0 and the component m> 0 is in the range of 10:90 to 0.1: 99.9. In addition, the component of said m = 0 and the component of m> 0 can be measured by a high performance liquid chromatography by a conventional method.

In the above general formula (5), Q represents a monosaccharide or disaccharide residue. Specific examples of monosaccharides include allose, altrose, glucose, mannose, gulose, idose, galactose, talose, ribose, arabinose, xylose, lyxose, and the like.

Hereinafter, structural examples of the compound having a monosaccharide residue represented by the general formula (5) are shown, but the present invention is not limited to these specific examples.

Specific examples of the disaccharide include trehalose, sucrose, maltose, cellobiose, gentiobiose, lactose, and isotrehalose.

Hereinafter, structural examples of the compound having a disaccharide residue represented by the general formula (5) are shown, but the present invention is not limited to these specific examples.

In the general formula (5), R represents an aliphatic group or an aromatic group. Here, the aliphatic group and the aromatic group may each independently have a substituent.

In the general formula (5), m is the total number of hydroxyl groups directly bonded to the monosaccharide or disaccharide residue, and l is directly bonded to the monosaccharide or disaccharide residue. This is the total number of — (O—C (═O) —R) groups present. And it is necessary that 3 ≦ m + 1 ≦ 8, and it is preferable that 4 ≦ m + 1 ≦ 8. Also, l ≠ 0. When l is 2 or more, the — (O—C (═O) —R) groups may be the same or different.

The aliphatic group in the definition of R may be linear, branched or cyclic, preferably has 1 to 25 carbon atoms, more preferably has 1 to 20 carbon atoms, and more preferably has 2 to 2 carbon atoms. 15 is particularly preferred. Specific examples of the aliphatic group include, for example, methyl, ethyl, n-propyl, iso-propyl, cyclopropyl, n-butyl, iso-butyl, tert-butyl, amyl, iso-amyl, tert-amyl, n- Examples include hexyl, cyclohexyl, n-heptyl, n-octyl, bicyclooctyl, adamantyl, n-decyl, tert-octyl, dodecyl, hexadecyl, octadecyl, didecyl and the like.

In addition, the aromatic group in the definition of R may be an aromatic hydrocarbon group or an aromatic heterocyclic group, and more preferably an aromatic hydrocarbon group. The aromatic hydrocarbon group preferably has 6 to 24 carbon atoms, more preferably 6 to 12 carbon atoms. Specific examples of the aromatic hydrocarbon group include benzene, naphthalene, anthracene, biphenyl, terphenyl and the like. As the aromatic hydrocarbon group, benzene, naphthalene, and biphenyl are particularly preferable. As the aromatic heterocyclic group, those containing at least one of an oxygen atom, a nitrogen atom or a sulfur atom are preferable. Specific examples of the heterocyclic ring include, for example, furan, pyrrole, thiophene, imidazole, pyrazole, pyridine, pyrazine, pyridazine, triazole, triazine, indole, indazole, purine, thiazoline, thiadiazole, oxazoline, oxazole, oxadiazole, quinoline, Examples thereof include isoquinoline, phthalazine, naphthyridine, quinoxaline, quinazoline, cinnoline, pteridine, acridine, phenanthroline, phenazine, tetrazole, benzimidazole, benzoxazole, benzthiazole, benzotriazole, tetrazaindene and the like. As the aromatic heterocyclic group, pyridine, triazine, and quinoline are particularly preferable.

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

(Synthesis example: Synthesis example of the compound represented by the general formula (5))

Four-headed Kolben equipped with a stirrer, a reflux condenser, a thermometer and a nitrogen gas inlet tube was charged with 34.2 g (0.1 mol) of sucrose, 180.8 g (0.8 mol) of benzoic anhydride, 379. 7 g (4.8 mol) was charged, the temperature was raised while bubbling nitrogen gas from a nitrogen gas introduction tube with stirring, and an esterification reaction was carried out at 70 ° C. for 5 hours. Next, the inside of the Kolben was depressurized to 4 × 10 ² Pa or less, and after excess pyridine was distilled off at 60 ° C., the inside of the Kolben was depressurized to 1.3 × 10 Pa or less and the temperature was raised to 120 ° C. Most of the acid and benzoic acid formed were distilled off. Then, 1 L of toluene and 300 g of a 0.5% by mass aqueous sodium carbonate solution were added, and the mixture was stirred at 50 ° C. for 30 minutes and then allowed to stand to separate a toluene layer. Finally, 100 g of water is added to the collected toluene layer, and after washing with water at room temperature for 30 minutes, the toluene layer is separated, and toluene is distilled off at 60 ° C. under reduced pressure (4 × 10 ² Pa or less). A mixture of Compound 1, Example Compound 2, Example Compound 3, Example Compound 4, and Example Compound 5 was obtained. When the obtained mixture was analyzed by HPLC and LC-MASS, exemplary compound 1 was 7% by mass, exemplary compound 2 was 58% by mass, exemplary compound 3 was 23% by mass, exemplary compound 4 was 9% by mass, exemplary compound 5 Was 3% by mass. In addition, Example Compound 1, Example Compound 2, Example Compound 3, Example Compound 4, and Example Compound 5 having a purity of 100% were obtained by purifying a part of the obtained mixture by silica gel column chromatography.

The sugar ester compound is preferably contained in an amount of 0.1 to 30% by mass, more preferably 2 to 20% by mass with respect to 100% by mass of the total amount of the base material layer.

<Retardation adjuster>
The base material layer may contain a retardation adjusting agent. The retardation adjusting agent is an additive capable of adjusting the retardation development property of the film by its addition. There is no restriction | limiting in particular about the specific structure, A conventionally well-known knowledge can be referred suitably. Moreover, although there exists the retardation adjusting agent which has the effect of adjusting wavelength dispersion simultaneously, you may use this.

Examples of the retardation adjusting agent that can be used in the present invention include aromatic compounds having two or more aromatic rings as described in EP 911,656A2. Two or more aromatic compounds may be used in combination. The aromatic ring of the aromatic compound includes an aromatic heterocyclic ring in addition to the aromatic hydrocarbon ring. An aromatic heterocyclic ring is particularly preferred, and the aromatic heterocyclic ring is generally an unsaturated heterocyclic ring. Of these, compounds having a 1,3,5-triazine ring are particularly preferred.

In addition, as another example of the retardation adjusting agent, a compound disclosed as a general formula (I) in JP 2010-163482 A can be mentioned. Specific examples of the general formula (I) are disclosed in paragraphs “0052” to “0058” of the publication. In addition, the compound disclosed as the general formula (I) in JP2010-163483A can also be used as a retardation adjusting agent. Specific examples of the general formula (I) are disclosed in paragraphs “0054” to “0068” of the publication.

The retardation adjusting agent is preferably contained in an amount of 0.1 to 30% by mass, more preferably 2 to 20% by mass with respect to 100% by mass of the total amount of the base material layer.

<polyester>
It is also preferable that the base material layer contains the following polyester.

(Polyester represented by general formula (d) or (e))
The base material layer may contain polyester represented by the following general formula (d) or (e).

(In the formula, B1 represents a monocarboxylic acid, G represents a divalent alcohol, A represents a dibasic acid, and B1, G, and A do not contain an aromatic ring. M represents the number of repetitions. )

(In the formula, B2 represents a monoalcohol, G represents a divalent alcohol, A represents a dibasic acid, and B2, G, and A do not contain an aromatic ring. N represents the number of repetitions.)
In the general formulas (d) and (e), B1 represents a monocarboxylic acid component, B2 represents a monoalcohol component, G represents a divalent alcohol component, A represents a dibasic acid component, and these are synthesized. It represents what has been done. B1, B2, G, and A are all characterized by containing no aromatic ring. m and n represent the number of repetitions.

The monocarboxylic acid represented by B1 is not particularly limited, and known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, and the like can be used.

Preferred examples of the monocarboxylic acid include the following, but the present invention is not limited to this.

As the aliphatic monocarboxylic acid, a straight-chain or side-chain fatty acid having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1-20 carbon atoms, and particularly preferably has 1-12 carbon atoms. When acetic acid is contained, the compatibility with cellulose acylate is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid.

Preferred aliphatic monocarboxylic acids include formic acid, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, Saturated fatty acids such as tridecylic acid, myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccellic acid; Examples thereof include unsaturated fatty acids such as acid, oleic acid, sorbic acid, linoleic acid, linolenic acid, and arachidonic acid.

The monoalcohol component represented by B2 is not particularly limited, and known alcohols can be used. For example, an aliphatic saturated alcohol or aliphatic unsaturated alcohol having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. More preferably, it has 1-20 carbon atoms, and particularly preferably has 1-12 carbon atoms.

Examples of the divalent alcohol component represented by G include the following, but the present invention is not limited thereto. For example, ethylene glycol, diethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,5-pentanediol, , 6-hexanediol, 1,5-pentylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, etc., among which ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1 , 2-butylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexanediol, diethylene glycol and triethylene glycol are preferred, and 1,3-propylene glycol, 1,4 Butylene glycol 1,6-hexanediol, diethylene glycol is preferably used.

The dibasic acid (dicarboxylic acid) component represented by A is preferably an aliphatic dibasic acid or an alicyclic dibasic acid. Examples of the aliphatic dibasic acid include malonic acid, succinic acid, glutaric acid, Adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, dodecanedicarboxylic acid, etc., especially aliphatic dicarboxylic acids having 4 to 12 carbon atoms, and at least one selected from these are used. Can be done. That is, two or more dibasic acids may be used in combination.

M and n represent the number of repetitions and are preferably 1 or more and 170 or less.

(Polyester represented by general formula (f) or (g))
The base material layer may contain polyester represented by the following general formula (f) or (g).

(In the formula, B1 represents a monocarboxylic acid having 1 to 12 carbon atoms, G represents a divalent alcohol having 2 to 12 carbon atoms, and A represents a dibasic acid having 2 to 12 carbon atoms. B1, G , A does not contain an aromatic ring, and m represents the number of repetitions.)

(In the formula, B2 represents a monoalcohol having 1 to 12 carbon atoms, G represents a divalent alcohol having 2 to 12 carbon atoms, and A represents a dibasic acid having 2 to 12 carbon atoms. B2, G, (A does not contain an aromatic ring. N represents the number of repetitions.)
In the general formulas (f) and (g), B1 represents a monocarboxylic acid component, B2 represents a monoalcohol component, G represents a divalent alcohol component having 2 to 12 carbon atoms, and A represents 2 to 2 carbon atoms. Twelve dibasic acid components are represented and synthesized by them. B1, G, and A do not contain an aromatic ring. m and n represent the number of repetitions. B1 and B2 have the same meanings as B1 and B2 in the general formula (d) or (e) described above. G and A correspond to an alcohol component or a dibasic acid component having 2 to 12 carbon atoms in G and A in the general formula (d) or (e).

The number average molecular weight of the polyester is 1000 or more and 10,000 or less. If the number average molecular weight is less than 1000, breakage tends to occur at high temperature and high magnification stretching, and if it exceeds 10,000, whitening due to phase separation tends to increase.

Polyester polycondensation is performed by conventional methods. For example, a direct reaction of the dibasic acid with a glycol, a hot melt condensation method using the dibasic acid or an alkyl ester thereof, for example, a polyesterification reaction or a transesterification reaction between a methyl ester of a dibasic acid and a glycol. Alternatively, it can be easily synthesized by any method of dehydrohalogenation reaction between acid chloride of these acids and glycol, but it is preferable to synthesize a polyester having a weight average molecular weight not so large by direct reaction.

Polyester having a high distribution on the low molecular weight side has very good compatibility with cellulose acylate, and after forming the film, it is possible to obtain a cellulose acylate film having low moisture permeability and high transparency. A conventional method can be used as a method for adjusting the molecular weight without particular limitation. For example, although depending on the polymerization conditions, when a method of blocking the molecular ends with a monovalent acid or monovalent alcohol is used, the molecular weight is adjusted by adjusting the addition amount of these monovalent raw material compounds. be able to. In this case, it is preferable from the viewpoint of the stability of the polymer to adjust the addition amount of the monovalent acid. For example, acetic acid, propionic acid, butyric acid and the like can be mentioned, but it is preferable to select those which are not distilled out of the system during the polycondensation reaction but are easily distilled off when stopped and removed from the reaction system. For this purpose, a plurality of compounds may be used in combination. In the case of a direct reaction, the weight average molecular weight can also be adjusted by measuring the timing for stopping the reaction based on the amount of water produced during the reaction. In addition, the molecular weight can be adjusted by biasing the number of moles of glycol or dibasic acid to be charged, or the molecular weight can be adjusted by controlling the reaction temperature.

The polyester is preferably contained in an amount of 0.1 to 30% by mass and more preferably 2 to 20% by mass with respect to 100% by mass of the total amount of the base material layer.

<Ultraviolet absorber>
The base material layer can also contain an ultraviolet absorber. The ultraviolet absorber is intended to improve durability by absorbing ultraviolet light having a wavelength of 400 nm or less. In particular, the transmittance at a wavelength of 370 nm is preferably 10% or less, more preferably 5% or less, Preferably it is 2% or less. In addition, when a base material layer contains a ultraviolet absorber, it is preferable that the said ultraviolet absorber is contained 2 or more types.

Although the ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body.

For example, 5-chloro-2- (3,5-di-sec-butyl-2-hydroxylphenyl) -2H-benzotriazole, (2-2H-benzotriazol-2-yl) -6- (linear and side Chain dodecyl) -4-methylphenol, 2-hydroxy-4-benzyloxybenzophenone, 2,4-benzyloxybenzophenone, and the like, and tinuvin 109, tinuvin 171, tinuvin 234, tinuvin 326, tinuvin 327, tinuvin 328, etc. These are commercially available products made by BASF Japan Ltd. and can be preferably used.

The UV absorbers preferably used in the present invention are benzotriazole UV absorbers, benzophenone UV absorbers, and triazine UV absorbers, particularly preferably benzotriazole UV absorbers and benzophenone UV absorbers. . In addition, a discotic compound such as a compound having a 1,3,5 triazine ring is also preferably used as the ultraviolet absorber. As the UV absorber, a polymer UV absorber can also be preferably used, and in particular, a polymer type UV absorber described in JP-A-6-148430 is preferably used.

The method of adding the UV absorber can be added to the dope after dissolving the UV absorber in an alcohol such as methanol, ethanol or butanol, an organic solvent such as methylene chloride, methyl acetate, acetone or dioxolane or a mixed solvent thereof. Or you may add directly in dope composition. Moreover, what does not melt | dissolve in an organic solvent like inorganic powder should just add to dope after disperse | distributing in an organic solvent and a cellulose-ester resin using a dissolver or a sand mill.

The ultraviolet absorber is preferably contained in an amount of 0.1 to 15% by mass, more preferably 1 to 10% by mass with respect to 100% by mass of the total amount of the base material layer.

<Infrared absorber>
The base material layer may include an infrared absorber. By setting it as such a structure, the reverse wavelength dispersion of a film can be adjusted.

The infrared absorber preferably has a maximum absorption in a wavelength region of 750 to 1100 nm, and more preferably has a maximum absorption in a wavelength region of 800 to 1000 nm. Moreover, it is preferable that the infrared absorber has substantially no absorption in the visible region.

As the infrared absorber, an infrared absorbing dye or an infrared absorbing pigment is preferably used, and an infrared absorbing dye is particularly preferably used.

The infrared absorbing dye includes an organic compound and an inorganic compound. It is preferable to use an infrared absorbing dye that is an organic compound. Organic infrared absorbing dyes include cyanine compounds, metal chelate compounds, aminium compounds, diimonium compounds, quinone compounds, squarylium compounds, and methine compounds. Infrared absorbing dyes are described in Coloring Materials, 61 [4] 215-226 (1988), and Chemical Industry, 43-53 (1986, May).

Investigating the types of dyes from the viewpoint of infrared absorption function or absorption spectrum, infrared absorbing dyes developed in the technical field of silver halide photographic light-sensitive materials are excellent. Infrared absorbing dyes developed in the technical field of silver halide photographic light-sensitive materials include dihydroperimidine squarylium dyes (described in US Pat. No. 5,380,635 and Japanese Patent Application No. 8-189817), cyanine dyes (Japanese Patent Application Laid-Open No. Sho). Nos. 62-123454, 3-138640, 3-221542, 3-226636, 5-313305, 6-43583, Japanese Patent Application No. 7-269097 and European Patent No. 0430244), pyrylium dyes (described in JP-A-3-138640, JP-A-3-21542), diimonium dye (described in JP-A-3-138640, JP-A-3-21542), pyrazolopyridone Dyes (described in JP-A-2-282244), indoaniline dyes (JP-A-5-323500) No. 5-323501), polymethine dyes (Japanese Unexamined Patent Publication Nos. 3-26765 and 4-190343 and European Patent No. 377961), oxonol dyes (Japanese Unexamined Patent Publication No. 3-9346) Description), anthraquinone dyes (described in JP-A-4-13654), naphthalocyanine dyes (described in US Pat. No. 5,099,899) and naphtholactam dyes (described in European Patent 568267). As for these infrared absorbers, only 1 type may be used independently and 2 or more types may be used together.

The infrared absorbing agent is preferably contained in an amount of 0.1 to 30% by mass, more preferably 2 to 20% by mass with respect to 100% by mass of the total amount of the base material layer.

<Matting agent (fine particles)>
In order to improve handling properties, for example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, silicic acid. It is preferable to contain inorganic fine particles such as magnesium and calcium phosphate and fine particles such as a crosslinked polymer as a matting agent. Of these, silicon dioxide is preferable because it can reduce the haze of the film.

The average primary particle diameter of the fine particles is preferably 20 nm or less, more preferably 5 to 16 nm, and particularly preferably 5 to 12 nm.

These fine particles preferably form secondary particles having a particle size of 0.1 to 5 μm and are contained in the film, and the preferable average particle size is 0.1 to 2 μm, more preferably 0.2 to 0. .6 μm. As a result, irregularities having a height of about 0.1 to 1.0 μm are formed on the film surface, thereby providing appropriate slipperiness to the film surface.

The average primary particle size of the fine particles used in the present invention is measured by observing the particles with a transmission electron microscope (magnification 500,000 to 2,000,000 times), observing 100 particles, measuring the particle size, and measuring the average value. Is the average primary particle size.

The apparent specific gravity of the fine particles is preferably 70 g / liter or more, more preferably 90 to 200 g / liter, and particularly preferably 100 to 200 g / liter. A higher apparent specific gravity is preferable because a high-concentration dispersion can be produced and haze and aggregates are improved, and it is particularly preferably used when preparing a dope having a high solid content concentration.

Silicon dioxide fine particles having an average primary particle diameter of 20 nm or less and an apparent specific gravity of 70 g / liter or more are, for example, a mixture of vaporized silicon tetrachloride and hydrogen burned in air at 1000 to 1200 ° C. Can be obtained. For example, Aerosil R812, Aerosil 200V, Aerosil R972V (above, manufactured by Nippon Aerosil Co., Ltd.) are commercially available and can be used.

The apparent specific gravity described above is calculated by the following equation by measuring a weight of silicon dioxide fine particles in a graduated cylinder and measuring the weight.

The matting agent (fine particles) is preferably contained in an amount of 0.01 to 5% by mass and more preferably in an amount of 0.1 to 3% by mass with respect to 100% by mass of the total amount of the base material layer. preferable.

<Colorant>
The base material layer may contain a colorant. The “colorant” means a dye or a pigment. In the present invention, those having an effect of making the color tone of the liquid crystal screen blue, adjusting the yellow index, and reducing haze are particularly preferable. Various dyes and pigments can be used as the colorant, and anthraquinone dyes, azo dyes, phthalocyanine pigments and the like are particularly effective.

The colorant is preferably contained in an amount of 0.01 to 5% by mass, more preferably 0.1 to 3% by mass with respect to 100% by mass of the total amount of the base material layer.

As mentioned above, although the base material layer demonstrated the form containing a cellulose-ester resin as preferable embodiment, in the polarizing plate which concerns on this form, it is preferable that a base material layer is what is called a "zero phase difference film." Because the base material layer that functions as a polarizing plate protective film is a zero retardation film, there is no retardation even when a high-magnification stretching process is performed, and rainbow unevenness does not appear when incorporated in an image display device. There are advantages. In addition, if this is expressed quantitatively, the base material layer has the following mathematical formula (1) and the following mathematical formula (2):

(In the formula, nx represents the refractive index in the slow axis direction in the film plane, ny represents the refractive index in the fast axis direction in the film plane, nz represents the refractive index in the film thickness direction, and d represents the film. The refractive index is measured at a wavelength of 590 nm under an environment of 23 ° C. and 55% RH)
For Ro and Rth respectively represented by

Is preferably satisfied. Ro is more preferably -4 to 4, and particularly preferably -3 to 3. Rth is more preferably −4 to 4, and particularly preferably −3 to 3. In addition, in order to control these Ro and Rth to the values within the above-described range, the composition of the film, the stretching conditions, the type and amount of the retardation adjusting agent, and the like may be appropriately adjusted during the production of the base material layer. Good.

The hydrophilic polymer layer and the base material layer described above are preferably bonded through an adhesive. There is no restriction | limiting in particular about the specific structure of an adhesive agent, Any adhesive agent will be used if it does not impair the effect of this invention. An example of the adhesive is an aqueous polyvinyl alcohol solution (so-called water paste).

Also, a photo-curable adhesive may be used as the adhesive. The photocurable adhesive preferably contains an epoxy compound and a cationic polymerization initiator.

There are no particular restrictions on the specific composition of the epoxy compound and cationic polymerization initiator contained in such a photocurable adhesive and the amount of each component, but from the viewpoint of adhesiveness, the epoxy compound is a polyvalent epoxy. A compound (an epoxy compound having at least two epoxy groups in the molecule) is preferable. The polyvalent epoxy compound includes an aromatic polyvalent epoxy compound having at least two epoxy groups and an aromatic ring in the molecule, and at least two epoxy groups in the molecule, at least one of which is alicyclic One carbon atom of a ring (usually an oxirane ring) that has an alicyclic polyvalent epoxy compound bonded to the ring, does not have an aromatic ring in the molecule, and contains an epoxy group and two carbon atoms to which it is bonded Is an aliphatic polyvalent epoxy compound in which is bonded to another aliphatic carbon atom. Examples of such polyvalent epoxy compounds include those represented by any one of the following general formulas (A) to (D).

(Wherein R ¹ to R ³ each independently represents an alkyl group or a halogen atom, L ¹ and L ² each independently represents a divalent aliphatic organic group, and M represents oxygen Represents an atom or a nitrogen atom, A represents an m-valent linking group, a, b and c each independently represent an integer of 0 to 4, and x and y each independently represents a real number of 0 to 20 Wherein l represents 1 or 2, and m represents an integer of 2 to 4.)
In the general formulas (A), (B), and (D), L ¹ and L ² are, for example,

In general formula (C), as A,

Etc.

The alkyl group for R ¹ , R ² , and R ³ preferably has 1 to 3 carbon atoms, and examples of the halogen atom include Br, Cl, and F.

Hereinafter, although the specific example of the polyhydric epoxy compound represented by general formula (A), (B), (C) or (D) is shown, this invention is not limited to these.

In the compound (IV-1), n is an integer of 0 to 20.

Note that the variables x and y in the structural formula are real numbers and may be anything in the range of 0 to 20, respectively. The reason why x and y are not necessarily integers is that an epoxy compound having several kinds of integer values is mixed in a certain ratio and shows an average value thereof. These polyvalent epoxy compounds may be used alone or in combination of two or more.

Further, other examples of the polyvalent epoxy compound include those represented by any of the following general formulas (E) to (O).

(Wherein R ⁴ to R ²⁵ each independently represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and when R ⁴ to R ²⁵ are alkyl groups, the position bonded to the alicyclic ring is an arbitrary number of positions 1 to 6 of. an alkyl group having 1 to 6 carbon atoms may be linear, may be branched, it may have an alicyclic ring .Y ⁸ Represents an oxygen atom or an alkanediyl group having 1 to 20 carbon atoms, and Y ¹ to Y ⁷ may each independently be linear or branched and have an alicyclic ring. An optionally substituted alkanediyl group having 1 to 20 carbon atoms, and n, p, q and r each independently represents a real number of 0 to 20.)
Among these, the alicyclic diepoxy compound represented by the general formula (F) is preferable because it is easily available. The alicyclic diepoxy compound of the general formula (F) includes 3,4-epoxycyclohexylmethanol (an alkyl group having 1 to 6 carbon atoms may be bonded to the cyclohexane ring) and 3,4-epoxycyclohexanecarboxylic acid. An esterified product of an acid (an alkyl group having 1 to 6 carbon atoms may be bonded to the cyclohexane ring). Specific examples thereof include the following compounds.

3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate [a compound in which R ⁶ = R ⁷ = H and n = 0 in the general formula (F)],
3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate [in the general formula (F), R ⁶ = 6-methyl, R ⁷ = 6-methyl, n = 0 Compound] and the like.

The above-described polyvalent epoxy compounds and oxetane compounds (described later) added as necessary are cured by cationic polymerization. Therefore, it is preferable that a photocationic polymerization initiator is blended in the photocurable adhesive. This cationic photopolymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and starts an epoxy group polymerization reaction.

By blending such a cationic photopolymerization initiator, curing at room temperature is possible, and the need to consider the heat resistance of the polarizer and distortion due to expansion or contraction is reduced, and the cellulose acylate film adheres well. be able to. In addition, since the cationic photopolymerization initiator acts catalytically upon irradiation with active energy rays, it is excellent in storage stability and workability even when mixed with an epoxy compound or an oxetane compound described later. Examples of compounds that generate cation species and Lewis acids upon irradiation with active energy rays include onium salts such as aromatic diazonium salts, aromatic iodonium salts and aromatic sulfonium salts, and iron-allene complexes.

Examples of the aromatic diazonium salt include the following compounds.

Benzenediazonium hexafluoroantimonate,
Benzenediazonium hexafluorophosphate,
Benzenediazonium hexafluoroborate, etc.

Examples of aromatic iodonium salts include the following compounds.

Diphenyliodonium tetrakis (pentafluorophenyl) borate,
Diphenyliodonium hexafluorophosphate,
Diphenyliodonium hexafluoroantimonate,
Di (4-nonylphenyl) iodonium hexafluorophosphate, etc.

Examples of the aromatic sulfonium salt include the following compounds.

Triphenylsulfonium hexafluorophosphate,
Triphenylsulfonium hexafluoroantimonate,
Triphenylsulfonium tetrakis (pentafluorophenyl) borate,
Diphenyl [4- (phenylthio) phenyl] sulfonium hexafluorophosphate,
Diphenyl [4- (phenylthio) phenyl] sulfonium hexafluoroantimonate,
4,4′-bis (diphenylsulfonio) diphenyl sulfide bishexafluorophosphate,
4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate,
4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluorophosphate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate,
4-phenylcarbonyl-4′-diphenylsulfonio-diphenyl sulfide hexafluorophosphate,
4- (p-tert-butylphenylcarbonyl) -4′-diphenylsulfonio-diphenyl sulfide hexafluoroantimonate,
4- (p-tert-butylphenylcarbonyl) -4′-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate and the like.

Examples of the iron-allene complex include the following compounds.

Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,
Cumene-cyclopentadienyl iron (II) hexafluorophosphate,
Xylene-cyclopentadienyl iron (II) -tris (trifluoromethylsulfonyl) methanide and the like.

These photocationic polymerization initiators may be used alone or in combination of two or more. Among these, aromatic sulfonium salts are particularly preferably used because they have ultraviolet absorption characteristics even in a wavelength region of 300 nm or more, and therefore can provide a cured product having excellent curability and good mechanical strength and adhesive strength. It is done.

Commercially available cationic photopolymerization initiators can be easily obtained. For example, “Kayarad PCI-220” and “Kayarad PCI-620” (above, Nippon Kayaku Co., Ltd.) ), “UVI-6992” (manufactured by Dow Chemical Co.), “Adekaoptomer SP-150”, “Adekaoptomer SP-170” (manufactured by ADEKA Corporation), “CI-5102”, “CIT” -1370 "," CIT-1682 "," CIP-1866S "," CIP-2048S "," CIP-2064S "(manufactured by Nippon Soda Co., Ltd.)," DPI-101 "," DPI-102 " “DPI-103”, “DPI-105”, “MPI-103”, “MPI-105”, “BBI-101”, “BBI-102”, “BBI-103”, “BB -105 "," TPS-101 "," TPS-102 "," TPS-103 "," TPS-105 "," MDS-103 "," MDS-105 "," DTS-102 "," DTS-103 "(Midori Chemical Co., Ltd.)," PI-2074 "(Rhodia Co., Ltd.)," Irgacure 250 "," Irgacure PAG103 ", Irgacure PAG108", Irgacure PAG121 ", Irgacure PAG203 (above, manufactured by Ciba) ), “CPI-100P”, “CPI-101A”, “CPI-200K”, “CPI-210S” (manufactured by San Apro Co., Ltd.) and the like, and in particular, diphenyl [4- (phenylthio) phenyl] “UVI-6992” manufactured by Dow Chemical Co., which contains sulfonium as a cation component, Made in "CPI-100P", "CPI-101A", "CPI-200K", "CPI-210S" is preferable.

The proportion of the photocationic polymerization initiator is preferably in the range of 0.5 to 20% by mass based on the entire photocurable adhesive. If the ratio is 0.5% by mass or more, curing of the adhesive is sufficiently achieved, and mechanical strength and adhesive strength are ensured. On the other hand, if the ratio is 20% by mass or less, an increase in hygroscopicity of the cured product accompanying an increase in the ionic substance in the cured product and a decrease in durability due to the increase are suppressed.

The photocurable adhesive may further contain an oxetane compound or an unsaturated compound, if necessary, in addition to the components described above. Moreover, when a photocurable adhesive agent contains an unsaturated compound, it is preferable to further contain radical photopolymerization initiator. Still other components include photosensitizers, thermal cationic polymerization initiators, polyols, silane coupling agents, ion trapping agents, antioxidants, light stabilizers, chain transfer agents, sensitizers, tackifiers, Thermoplastic resins, fillers, flow regulators, plasticizers, antifoaming agents, leveling agents, dyes, organic solvents and the like can be mentioned.

As described above, in the stretched laminate in which the hydrophilic polymer layer and the base material layer are laminated and stretched, the hydrophilic polymer layer functions as a polarizer, and the base material layer serves as a polarizing plate protective film. Function. Thereby, the stretched laminate can be used as a polarizing plate. Here, the conventionally well-known polarizing plate protective film may further be bonded by the surface on the opposite side to a base material layer of the hydrophilic polymer layer which functions as a polarizer. A commercially available cellulose ester film can be used as such a polarizing plate protective film. Commercially available cellulose ester films include, for example, Konica Minoltac® KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UA, KC4UY, KC4UE, KC8UE, KC8UY-HA, KC8UX-H-K, -NC, KC4UXW-RHA-NC (manufactured by Konica Minolta Advanced Layer Co., Ltd.) and the like are preferably used. Alternatively, it is also preferable to use a polarizing plate protective film that also serves as an optical compensation film having an optical anisotropic layer formed by aligning liquid crystal compounds such as discotic liquid crystal, rod-shaped liquid crystal, and cholesteric liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP2003-98348A. By using in combination with the polarizing plate according to the present invention, a polarizing plate having excellent flatness and a stable viewing angle expansion effect can be obtained. In addition, as a polarizing plate protective film located in the side far from a liquid crystal cell, or on the said film, it is also possible to arrange | position the film which has other functionality, when improving the quality of a display apparatus. For example, anti-reflection (anti-reflection (AR)), anti-glare (anti-glare (AG)), scratch resistance (hard coat (HC)), low reflection (low reflection (LR)), dust adhesion prevention, brightness improvement, anti-static A film containing a known functional layer as a display for antifouling and back coating can be used as a polarizing plate protective film. Or you may affix separately the film containing these functional layers on the surface of polarizing plate protective films, such as a general purpose TAC film.

The polarizing plate having the above-described configuration can be configured by further bonding a protective film on one side and a separate film on the other side. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the display panel. Moreover, a separate film is used in order to cover the contact bonding layer bonded to a panel, and is used for the surface side which bonds a polarizing plate to a liquid crystal cell.

In the polarizing plate according to the present invention, the film thickness of the stretched laminate (the laminate of the above-described hydrophilic polymer layer and the base material layer and stretched) is preferably 10 to 100 μm. More preferably, the thickness is 20 to 95 μm, and still more preferably 30 to 90 μm. When the film thickness of the stretched laminate is 10 μm or more, the reworkability at the time of panel bonding is sufficient. On the other hand, when the film thickness of the stretched laminate is 100 μm or less, advantages such as curling suppression of the polarizing plate, thinning of the member, and weight reduction are obtained.

Further, the polarizing plate according to the present invention is characterized in that the variation in curl behavior under different environments is small. Specifically, the polarizing plate according to the present invention, the curl _{C 1} under 23 ° C. 55% RH environment, the difference [Delta] C ₌ the curl _{C 2} under 40 ° C. 20% RH environment _| C 1 -C ₂ | Is characterized in that ΔC ≦ 80 [1 / m] is satisfied. Here, ΔC preferably satisfies ΔC ≦ 60, more preferably satisfies ΔC ≦ 50, and more preferably satisfies ΔC ≦ 40. As described above, in the present invention, focusing on the physical properties of the coating type polarizing plate, the coating type polarizing plate is configured such that the variation in curl behavior under different environments is reduced, so that the display device can display the panel. It has been found that a polarizing plate capable of suppressing the occurrence of color unevenness is provided. Incidentally, C ₁ and C _2, as well as the value of [Delta] C, which should be adopted a value determined by the method described in the column of Examples described later. In order to control these values, the elastic modulus of the first base material layer is matched with the elastic modulus of the second base material layer at the time of producing the polarizing plate. It is possible to perform operations such as appropriately adjusting the thickness, controlling the film thickness to a suitable thickness, and selecting a suitable thermoplastic resin species.

≪Production method of polarizing plate≫
There is no restriction | limiting in particular about the manufacturing method of the polarizing plate (stretching laminated body) which concerns on this invention, It can manufacture suitably, referring the description of the column of the conventionally well-known knowledge and the Example mentioned later. An example of a method for producing a polarizing plate (stretched laminate) can be obtained, for example, by applying an aqueous solution containing a hydrophilic polymer to a base material layer and drying it to obtain a laminate. By such coating, the base material layer and the hydrophilic polymer layer are laminated directly with the base material layer and the hydrophilic polymer layer, or preferably via a layer of a photocurable adhesive, so that the base material layer and the hydrophilic polymer layer are hydrophilic. A laminated body in which the conductive polymer layer is integrated is obtained.

There is no particular limitation on the method for producing the base material layer, and conventionally known knowledge relating to the method for producing a film containing a cellulose ester resin may be appropriately referred to. The base material layer is preferably formed by a solution casting method using a dope solution prepared in advance, but if possible, the base material layer may be formed by a melt casting method.

The base material layer may be subjected to a stretching treatment in advance before the application of the aqueous solution containing the hydrophilic polymer. The stretching process can be uniaxial stretching, biaxial stretching, oblique stretching, or the like. Uniaxial stretching may be either longitudinal stretching performed in the longitudinal direction of the base material layer or transverse stretching performed in the width direction of the base material layer. In transverse stretching, the film can be contracted in the longitudinal direction while stretching in the width direction. Examples of the transverse stretching method include a fixed end uniaxial stretching method in which one end is fixed via a tenter, and a free end uniaxial stretching method in which one end is not fixed. Examples of the longitudinal stretching method include an inter-roll stretching method, a compression stretching method, and a stretching method using a tenter. The stretching process can be performed in multiple stages. In addition, when the extending | stretching process with respect to a base material layer is uniaxial stretching, it is preferable that it is longitudinal stretching (stretching to MD direction).

The temperature during the stretching treatment of the base material layer is not particularly limited, but is preferably 130 to 200 ° C, more preferably 150 to 180 ° C. Further, the stretching treatment of the base material layer is preferably performed such that the total stretching ratio in all directions is in the range of 1.1 to 10 times the original length of the base material layer. Preferably it is 2-6 times, more preferably 3-5 times.

When the substrate layer is composed of a laminate of two or more layers, such a substrate layer can be produced by a conventionally known method for producing a resin laminate. For example, as described in the Examples section which will be described later, two types of dope solutions having different compositions are prepared, a film is prepared by a solution casting method using one, and the film is dried and the other A base material layer in which two base material layers are laminated can be produced by further casting and drying the dope solution. In addition, you may perform an extending | stretching process with respect to the base material layer which has the laminated | multilayer structure independently of the 1st layer film as needed.

An aqueous solution containing a hydrophilic polymer can be prepared by dissolving a powder of a hydrophilic polymer or a pulverized product or a cut product of a hydrophilic polymer film in appropriately heated water (hot water). . Application of the aqueous solution onto the base material layer is performed by a wire bar coating method, a roll coating method such as reverse coating or gravure coating, a spin coating method, a screen coating method, a fountain coating method, a dipping method, or a spray method. Etc. can be selected and adopted as appropriate. When the base material layer has a layer of a photocurable adhesive, the aqueous solution is applied directly to the layer. When the base material layer does not have the layer, the aqueous solution is applied directly to the base material layer. The drying temperature is usually 50 to 200 ° C., preferably 80 to 150 ° C., and the drying time is usually about 5 to 30 minutes.

The laminate used in the present invention can also be formed by co-extrusion of a base material layer forming material and a hydrophilic polymer layer forming material. A laminate in which the base material layer and the hydrophilic polymer layer are integrated may be obtained by such coextrusion. For coextrusion, the material of the base material layer and the material of the hydrophilic polymer layer are respectively charged into the coextrusion machine as a forming material for each layer, and the thickness of the base material layer and the hydrophilic polymer layer to be coextruded is desired. It is preferable to control to be in the range.

Subsequently, the laminate before stretching obtained above is subjected to stretching treatment and dyeing treatment with a dichroic substance. The stretched laminate subjected to the above treatments has a dichroic substance adsorbed on the resulting hydrophilic polymer layer by stretching the hydrophilic polymer layer and dyeing with a dichroic substance. Functions as a polarizer.

The stretching treatment is performed by subjecting the laminate obtained above to uniaxial stretching, biaxial stretching, or oblique stretching. This stretching process can also be performed in multiple stages. In addition, when the base material layer is not previously stretched, and the stretching treatment of the laminate is uniaxial stretching, the uniaxial stretching is preferably longitudinal stretching (stretching in the MD direction). On the other hand, when the base material layer has been previously stretched in the longitudinal direction (stretching in the MD direction) and the stretching treatment of the laminate is uniaxial stretching, the uniaxial stretching is transverse stretching (stretching in the TD direction). ) Is preferable.

Further, the temperature at the time of the stretching treatment of the laminate is not particularly limited, but is preferably 130 to 200 ° C, more preferably 150 to 180 ° C. In addition, the stretching process of the laminate may be performed so that the total stretch ratio in all directions is in the range of 2 to 10 times the original length of the laminate. Preferably it is 3 to 8 times, more preferably 3 to 7 times.

The dyeing process is performed by adsorbing a dichroic substance to the hydrophilic polymer layer of the laminate. Since the dichroic substance is as described above, the description is omitted here. The dyeing process is performed, for example, by immersing the laminate in a solution (dyeing solution) containing a dichroic substance. As the staining solution, a solution in which a dichroic substance is dissolved in a solvent can be used. As the solvent, water is generally used, but an organic solvent compatible with water may be further added. The concentration of the dichroic substance in the dyeing solution is preferably in the range of 0.01 to 10% by mass, more preferably in the range of 0.02 to 7% by mass, and 0.025 to 5% by mass. % Is particularly preferred.

Further, when iodine is used as the dichroic substance, it is preferable to further add an iodide because the dyeing efficiency can be further improved. Examples of the iodide include potassium iodide, lithium iodide, sodium iodide, zinc iodide, aluminum iodide, lead iodide, copper iodide, barium iodide, calcium iodide, tin iodide, and iodide. Examples include titanium. The addition ratio of these iodides is preferably 0.01 to 10% by mass, and more preferably 0.1 to 5% by mass in the dyeing solution. Among them, it is preferable to add potassium iodide, and the ratio (mass ratio) of iodine and potassium iodide is preferably in the range of 1: 5 to 1: 100, and in the range of 1: 6 to 1:80. More preferably, it is in the range of 1: 7 to 1:70.

The immersion time of the laminate in the dyeing solution is not particularly limited, but usually it is preferably in the range of 15 seconds to 5 minutes, more preferably 1 minute to 3 minutes. The temperature of the dyeing solution is preferably in the range of 10 to 60 ° C., more preferably in the range of 20 to 40 ° C. In the dyeing treatment, the dichroic substance is oriented by adsorbing the dichroic substance to the hydrophilic polymer layer of the laminate. The dyeing process can be performed before, simultaneously with, or after the stretching process of the laminate. From the viewpoint of satisfactorily orienting the dichroic material adsorbed on the hydrophilic polymer layer, the dyeing process is performed on the laminate. It is preferable to carry out after the treatment.

≪Display device≫
The polarizing plate according to the present invention can be used in various display devices such as a liquid crystal display device and an organic electroluminescence (EL) display device.

For example, by incorporating the polarizing plate according to the present invention into a liquid crystal display device, various liquid crystal display devices with excellent visibility can be produced. Moreover, since the polarizing plate according to the present invention is excellent in reworkability, the productivity of the display device can be greatly improved. Note that the polarizing plate of the present invention can be used for liquid crystal display devices of various drive systems such as STN, TN, OCB, HAN, VA (MVA, PVA), and IPS. Preferred are VA (MVA, PVA) type and IPS type liquid crystal display devices. In particular, it is preferably incorporated in an IPS mode liquid crystal display device.

The liquid crystal layer of the liquid crystal panel in the IPS mode type liquid crystal display device is homogeneously aligned parallel to the substrate surface in the initial state, and the director of the liquid crystal layer is parallel to the electrode wiring direction when no voltage is applied. The direction of the director of the liquid crystal layer shifts to a direction perpendicular to the electrode wiring direction when a voltage is applied, and the director direction of the liquid crystal layer is the direction of the director when no voltage is applied. When tilted in the direction of the electrode wiring by 45 ° compared to the liquid crystal layer when the voltage is applied, the azimuth angle of the polarization is rotated by 90 ° like a half-wave plate, and the transmission axis and polarization of the output side polarizing plate are rotated. The azimuth angles of the two coincide with each other to display white.

In general, the thickness of the liquid crystal layer is constant, but since it is driven by a transverse electric field, it may be possible to increase the response speed to switching by slightly increasing the thickness of the liquid crystal layer, but the thickness of the liquid crystal layer is constant. Even if it is not, it is possible to make the most of the effect, and there is little influence on the change in the thickness of the liquid crystal layer. The thickness of the liquid crystal layer is 2 to 6 μm, preferably 3 to 5.5 μm. The liquid crystal display device according to this embodiment can be preferably used for portable devices such as a tablet display device and a smartphone in addition to being used for a large liquid crystal television.

The details of the IPS mode type liquid crystal cell are not particularly limited, and it is of course possible to implement the present invention by referring to other conventionally known technical matters (for example, JP 2010-3060 A). .

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited thereto.

<Preparation of aqueous polyvinyl alcohol solution>
A polyvinyl alcohol film (average polymerization degree 2400, saponification degree 99 mol%, trade name: VF-PS2400) manufactured by Kuraray Co., Ltd., which is a film made of a hydrophilic polymer, is cut into small pieces having a side of 5 mm or less. And dissolved in hot water at 95 ° C. to prepare a polyvinyl alcohol aqueous solution having a concentration of 10% by mass.

<Preparation of polarizing plate>
(Preparation of optical film F1)
(Preparation of dope solution a)
Diacetylcellulose (L50, manufactured by Daicel) 30 parts by mass Methylene chloride 227 parts by mass Ethanol 43 parts by mass The above materials are put into a pressure-sealed container, heated to 80 ° C., and the pressure in the container is set to 2 atm. While the resin component was completely dissolved, a dope was obtained. The solution was Azumi Filter Paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. After filtering using 244, the dope was lowered to 35 ° C. and allowed to stand overnight to degas the dope.

(Preparation of dope solution b)
Dianal BR-85 (acrylic resin, manufactured by Mitsubishi Rayon Co., Ltd.) 70 parts by mass CAP482-20 (cellulose acetate propionate, manufactured by Eastman Chemical, acetyl substitution degree 0.18, propionyl substitution degree 2.60) 30 parts by mass Methylene chloride 252 parts by mass Ethanol 48 parts by mass The above materials were put into a pressurized sealed container, heated to 80 ° C., the pressure in the container was set to 2 atm, and the resin component was completely dissolved while stirring to obtain a dope. . The solution was Azumi Filter Paper No. After filtering using 244, the dope was lowered to 35 ° C. and allowed to stand overnight to degas the dope.

(Preparation of base material layer by solution casting method)
The dope solution b prepared above was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the amount of residual solvent reached 100%, and peeling was performed from the stainless steel band support with a peeling tension of 162 N / m.

The solvent was evaporated from the peeled web at 35 ° C., slit to 1.6 m width, and then dried at a drying temperature of 135 ° C. while being stretched 1.1 times in the width direction by a tenter.

At this time, the residual solvent amount when starting stretching with a tenter was 10%. After stretching with a tenter and relaxing at 130 ° C. for 5 minutes, drying is completed while transporting a drying zone at 120 ° C. and 130 ° C. with a number of rolls, slitting to a width of 1.5 m, and a width of 10 mm at both ends of the film. A knurling process having a height of 5 μm was performed, and an optical film was obtained by winding it around a 6-inch inner diameter core with an initial tension of 220 N / m and a final tension of 110 N / m.

The draw ratio in the MD direction calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.1 times. The residual solvent amount was 0.1%, the film thickness was 60 μm, and the number of turns was 4000 m.

Next, the wound film is unwound, the dope liquid a prepared above is cast on the unwound film, and dried at 50 ° C. until the residual solvent amount of the resin layer made of the dope liquid a becomes 100%. Thereafter, drying was carried out stepwise at 120 ° C. and 130 ° C., and drying was carried out until the residual solvent amount in the total film became 0.3%, and then wound to obtain an optical film F1. The thickness of the resin layer made of the dope liquid a was 15 μm.

(Preparation of polarizing plate PL1)
(Lamination process)
After coating the polyvinyl alcohol aqueous solution prepared above on the optical film F1 obtained above, it is dried at 120 ° C. for 10 minutes to form a hydrophilic polymer layer comprising a polyvinyl alcohol coating film having a thickness of 10 μm. Thus, a laminate was obtained.

(Extension process)
The laminate obtained above was stretched in a roll to roll at 145 ° C. in the longitudinal direction (MD direction) at a stretch ratio of 6 to obtain a stretched laminate.

(Dyeing process)
The stretched laminate obtained above was immersed in an iodine solution (mass ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Then, drying was performed for 4 minutes at 60 degreeC, and polarizing plate PL1 was obtained. In addition, the thickness of the base material layer (F1; after extending | stretching) in obtained PL1 was 30 micrometers. The thickness of the hydrophilic polymer layer (after stretching) in the polarizing plate PL1 was 2 μm.

(Preparation of optical film F2)
<Fine particle dispersion 1>
Fine particles (Aerosil R812 manufactured by Nippon Aerosil Co., Ltd.) 11 parts by weight Ethanol 89 parts by weight The above was stirred and mixed with a dissolver for 50 minutes, and then dispersed with Manton Gorin.

<Fine particle addition liquid 1>
The fine particle dispersion 1 was slowly added to the dissolution tank containing methylene chloride with sufficient stirring. Further, the particles were dispersed by an attritor so that the secondary particles had a predetermined particle size. This was filtered through Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle additive solution 1.

Methylene chloride 99 parts by mass Fine particle dispersion 1 5 parts by mass A main dope solution having the following composition was prepared. First, methylene chloride and ethanol were added to the pressure dissolution tank. Cellulose acetate having an acetyl substitution degree of 2.30 was added to a pressure dissolution tank containing a solvent while stirring. This is completely dissolved with heating and stirring. This was designated as Azumi Filter Paper No. The main dope solution was prepared by filtration using 244.

<Composition of main dope solution>
The following two types of dopes were prepared, and an optical film F2 having a structure of skin layer / core layer / skin layer was prepared by co-casting.

(Preparation of cellulose acylate dope for core layer)
Cellulose acetate (acetyl substitution degree 2.30) 100 parts by weight Triphenyl phosphate / biphenyl diphenyl phosphate copolymer (copolymer ratio 1: 1) 10 parts by weight Dichloromethane 406 parts by weight Methanol 61 parts by weight (cellulose acylate for skin layer) Preparation of dope)
Cellulose acetate (acetyl substitution degree 2.80) 100 parts by weight Triphenyl phosphate / biphenyl diphenyl phosphate copolymer (copolymer ratio 1: 1) 13 parts by weight Fine particle additive liquid 1 2 parts by weight Dichloromethane 406 parts by weight Methanol 61 parts by weight Each of the above compositions was put into a mixing tank and stirred to dissolve each component, and then filtered through a filter paper having an average pore size of 34 μm and a sintered metal filter having an average pore size of 10 μm to prepare each cellulose acylate dope. The dope was co-cast with a band casting machine so as to have a three-layer structure of skin layer / core layer / skin layer. Here, by adjusting the casting amount of each dope, the core layer is made the thickest. As a result, the film thickness after stretching is 15 μm for the core layer, 10 μm for the skin layer, and 35 μm in total. Went. A film peeled off from the band with a residual solvent amount of about 30% by mass was applied with hot air at 160 ° C. by a tenter and widened to a draw ratio of 1.32 times, and then 140 ° C. so that the draw ratio became 1.3 times. For 60 seconds. Thereafter, the tenter conveyance was shifted to the roll conveyance, and the film was further dried at 120 to 150 ° C. and wound up.

(Preparation of polarizing plate PL2)
(Lamination process)
After coating the polyvinyl alcohol aqueous solution prepared above on the obtained optical film F2, it was dried at 120 ° C. for 10 minutes to form a hydrophilic polymer layer composed of a polyvinyl alcohol coating film having a thickness of 10 μm. A laminate was obtained.

(Extension process)
The laminate obtained above was stretched at a stretch ratio of 2 in the longitudinal direction (MD direction) at 150 ° C. with a roll-to-roll to obtain a stretched laminate.

(Dyeing process)
The stretched laminate obtained above was immersed in an iodine solution (mass ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Then, drying was performed for 4 minutes at 60 degreeC, and polarizing plate PL2 was obtained. In addition, the thickness of the base material layer (F2; after extending | stretching) in obtained PL2 was 25 micrometers. The thickness of the hydrophilic polymer layer (after stretching) in the polarizing plate PL2 was 3 μm.

(Preparation of optical film F3)
An optical film F3 (thickness 55 μm) was produced by the method described in Example 1 of JP 2010-30225 A.

(Preparation of polarizing plate PL3)
(Lamination process)
On the obtained optical film F3, after coating the polyvinyl alcohol aqueous solution prepared above, it was dried at 120 ° C. for 10 minutes to form a hydrophilic polymer layer comprising a polyvinyl alcohol coating film having a thickness of 10 μm. A laminate was obtained.

(Dyeing process)
The stretched laminate obtained above was immersed in an iodine solution (mass ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Then, drying was performed for 4 minutes at 60 degreeC, and polarizing plate PL3 was obtained. In addition, the thickness of the base material layer (F3; after extending | stretching) in obtained PL3 was 40 micrometers. The thickness of the hydrophilic polymer layer (after stretching) in the polarizing plate PL3 was 3 μm.

(Preparation of optical film F4)
A laminate optical film F4 (thickness: 135 μm) was obtained by the method described in Example 1 of JP2011-76026A.

(Preparation of polarizing plate PL4)
(Lamination process)
On the obtained optical film F4, after applying the polyvinyl alcohol aqueous solution prepared above, it was dried at 120 ° C. for 10 minutes to form a hydrophilic polymer layer comprising a polyvinyl alcohol coating film having a thickness of 10 μm. A laminate was obtained.

(Extension process)
The laminate obtained above was stretched at a stretch ratio of 6 times in the longitudinal direction (MD direction) at 150 ° C. with a roll-to-roll to obtain a stretched laminate.

(Dyeing process)
The stretched laminate obtained above was immersed in an iodine solution (mass ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Then, drying was performed for 4 minutes at 60 degreeC, and polarizing plate PL4 was obtained. In addition, the thickness of the base material layer (F4; after extending | stretching) in obtained PL4 was 45 micrometers. The thickness of the hydrophilic polymer layer (after stretching) in the polarizing plate PL4 was 2 μm.

(Preparation of optical film F5)
Based on the description in Example 1 of JP-A-2009-192844, a laminate film F5 (thickness: 185 μm) was obtained.

(Preparation of polarizing plate PL5)
(Lamination process)
On the obtained optical film F5, after coating the polyvinyl alcohol aqueous solution prepared above, it was dried at 120 ° C. for 10 minutes to form a hydrophilic polymer layer comprising a polyvinyl alcohol coating film having a thickness of 10 μm. A laminate was obtained.

(Extension process)
The laminate obtained above is heated at 150 ° C. in a clip type tenter, stretched twice in the film width direction (TD direction), and then in the longitudinal direction at 150 ° C. with a roll-to-roll in a transport roll. The film was stretched in the MD direction at a stretch ratio of 5 to obtain a stretched laminate.

(Dyeing process)
The stretched laminate produced above was immersed in an iodine solution (mass ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Then, drying was performed for 4 minutes at 60 degreeC, and polarizing plate PL5 was obtained. In addition, the thickness of the base material layer (F5; after extending | stretching) in obtained PL5 was 25 micrometers. The thickness of the hydrophilic polymer layer (after stretching) in the polarizing plate PL5 was 0.5 μm.

(Preparation of optical film F6)
(Preparation of dope solution a)
Diacetylcellulose (L50, manufactured by Daicel) 50 parts by mass Methylene chloride 227 parts by mass Ethanol 43 parts by mass The above materials are put into a pressure-sealed container, heated to 80 ° C., and the pressure inside the container is set to 2 atm. While the resin component was completely dissolved, a dope was obtained. The solution was Azumi Filter Paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. After filtering using 244, the dope was lowered to 35 ° C. and allowed to stand overnight to degas the dope.

(Preparation of dope solution b)
Dianal BR-52 (acrylic resin, manufactured by Mitsubishi Rayon Co., Ltd.) 100 parts by mass Methylene chloride 252 parts by mass Ethanol 48 parts by mass The above materials are put into a pressure sealed container and heated to 80 ° C. to increase the pressure inside the container. The resin component was completely dissolved while stirring at 2 atmospheres to obtain a dope. The solution was Azumi Filter Paper No. 1 manufactured by Azumi Filter Paper Co., Ltd. After filtering using 244, the dope was lowered to 35 ° C. and allowed to stand overnight to degas the dope.

Next, the wound film is unwound, the dope liquid a prepared above is cast on the unwound film, and dried at 50 ° C. until the residual solvent amount of the resin layer made of the dope liquid a becomes 100%. Thereafter, drying was carried out stepwise at 120 ° C. and 130 ° C., and drying was carried out until the residual solvent amount in the total film became 0.3%, and then wound to obtain an optical film F6. The thickness of the resin layer made of the dope liquid a was 15 μm.

(Preparation of polarizing plate PL6)
(Lamination process)
On the obtained optical film F6, the aqueous polyvinyl alcohol solution prepared above was applied and then dried at 120 ° C. for 10 minutes to form a hydrophilic polymer layer composed of a 10 μm thick polyvinyl alcohol coating film. A laminate was obtained.

(Extension process)
The laminated body obtained above is heated at 150 ° C. in a clip type tenter, stretched twice in the film width direction, and then in the longitudinal direction (MD direction) at 150 ° C. by roll-to-roll with a transport roll. The film was stretched at a stretch ratio of 5 to obtain a stretched laminate.

(Dyeing process)
The stretched laminate obtained above was immersed in an iodine solution (mass ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Then, drying was performed for 4 minutes at 60 degreeC, and polarizing plate PL6 was obtained. In addition, the thickness of the base material layer (F6; after extending | stretching) in obtained PL6 was 15 micrometers. The thickness of the hydrophilic polymer layer (after stretching) in the polarizing plate PL6 was 0.5 μm.

(Production of polarizing plates PL7 and PL8)
In the production method of PL1, when an aqueous polyvinyl alcohol solution was applied on the obtained optical film F1, polyvinyl alcohol was applied so that the thickness of the finished coating layer was 25 μm or 32 μm, and a laminate was obtained. .

Thereafter, the corresponding polarizing plates PL7 and PL8 were produced in the same manner as the production method of PL1.

(Preparation of polarizing plate PL9)
In the production method of the optical film F1, when the prepared dope b is cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus, the finished film thickness of the optical film F1 is 250 μm. The die gap was adjusted so that Thereafter, the solvent was evaporated with a stainless steel band support until the residual solvent amount reached 100%, and the solvent was evaporated, and the stainless steel band support was peeled off at a peeling tension of 100 N / m.

At this time, the residual solvent amount when starting stretching with a tenter was 15%. After stretching with a tenter and relaxing at 130 ° C. for 5 minutes, drying is completed while transporting a drying zone at 120 ° C. and 130 ° C. with a number of rolls, slitting to a width of 1.5 m, and a width of 10 mm at both ends of the film. A knurling process having a height of 5 μm was performed, and an optical film was obtained by winding it around a 6-inch inner diameter core with an initial tension of 300 N / m and a final tension of 180 N / m.

The draw ratio in the MD direction calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.1 times. The residual solvent amount was 0.1%, the film thickness was 250 μm, and the number of turns was 1000 m.

Next, the wound film is unwound, the dope liquid a prepared above is cast on the unwound film, and dried at 50 ° C. until the residual solvent amount of the resin layer made of the dope liquid a becomes 100%. Thereafter, drying was carried out stepwise at 120 ° C. and 130 ° C., and drying was carried out until the residual solvent amount in the total film became 0.3%, and then wound to obtain an optical film F9. The thickness of the resin layer made of the dope liquid a was 15 μm.

(Lamination process)
On the obtained optical film F9, after coating the polyvinyl alcohol aqueous solution prepared above, it was dried at 120 ° C. for 10 minutes to form a hydrophilic polymer layer comprising a polyvinyl alcohol coating film having a thickness of 10 μm. A laminate was obtained.
(Extension process)
The laminate obtained above is heated at 145 ° C. in a clip-type tenter, stretched twice in the width direction of the film, and then in the longitudinal direction (MD direction) at 145 ° C. by roll-to-roll with a transport roll. The film was stretched at a stretch ratio of 6 to obtain a stretched laminate.

(Dyeing process)
The stretched laminate obtained above was immersed in an iodine solution (mass ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Then, drying was performed for 4 minutes at 60 degreeC, and polarizing plate PL9 was obtained. In addition, the thickness of the base material layer (F9; after extending | stretching) in obtained PL9 was 93 micrometers. The thickness of the hydrophilic polymer layer (after stretching) in the polarizing plate PL9 was 2 μm.

(Preparation of polarizing plate PL10)
In the production method of the optical film F1, when the prepared dope b is cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus, the finished film thickness of the optical film F1 is 280 μm. The die gap was adjusted so that Thereafter, the solvent was evaporated with a stainless steel band support until the residual solvent amount reached 100%, and the solvent was evaporated, and the stainless steel band support was peeled off at a peeling tension of 100 N / m.

The draw ratio in the MD direction calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.1 times. The residual solvent amount was 0.1%, the film thickness was 280 μm, and the number of turns was 1000 m.

Next, the wound film is unwound, the dope liquid a prepared above is cast on the unwound film, and dried at 50 ° C. until the residual solvent amount of the resin layer made of the dope liquid a becomes 100%. The film was dried stepwise at 120 ° C. and 130 ° C., and dried until the residual solvent amount in the total film became 0.3%, and then wound to obtain an optical film F10. The thickness of the resin layer made of the dope liquid a was 15 μm.

(Lamination process)
On the obtained optical film F10, the polyvinyl alcohol aqueous solution prepared above was applied and then dried at 120 ° C. for 10 minutes to form a hydrophilic polymer layer comprising a polyvinyl alcohol coating film having a thickness of 10 μm. A laminate was obtained.

(Extension process)
The laminate obtained above is heated at 145 ° C. in a clip-type tenter, stretched twice in the width direction of the film, and then in the longitudinal direction (MD direction) at 145 ° C. by roll-to-roll with a transport roll. The film was stretched at a stretch ratio of 6 to obtain a stretched laminate.

(Dyeing process)
The stretched laminate produced above was immersed in an iodine solution (mass ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Then, drying was performed for 4 minutes at 60 degreeC, and polarizing plate PL10 was obtained. In addition, the thickness of the base material layer (F10; after extending | stretching) in obtained PL10 was 103 micrometers. The thickness of the hydrophilic polymer layer (after stretching) in the polarizing plate PL10 was 2 μm.

(Preparation of polarizing plate PL11)
A polarizing plate PL11 (thickness: 41 μm) was produced by the method described in Example 1 of JP-A-2009-98653.

(Preparation of polarizing plate PL12)
A 120 μm-thick long roll polyvinyl alcohol film was immersed in 100 parts by mass of an aqueous solution containing 1 part by mass of iodine and 4 parts by mass of boric acid, and stretched in the transport direction 5 times at 50 ° C. to produce a polarizer.

A 2.5 mass% polyvinyl alcohol aqueous solution was applied to both surfaces of the polarizer produced above with a wire bar, and an optical film F3 saponified under the following conditions was bonded and dried to obtain a polarizing plate PL12. The obtained PL12 had a thickness of 92 μm.

(Saponification treatment)
The prepared optical film F3 was immersed in an aqueous KOH solution at 50 ° C. and 2.0 N for 60 seconds, and then washed with water.

(Preparation of polarizing plate PL13)
An optical film F4 was produced based on Examples (a) and (b) of JP2010-250091A. The optical film F3 produced above and the optical film F4 are bonded together, and the polyvinyl alcohol aqueous solution prepared above is applied onto the optical film F3, and then dried at 120 ° C. for 10 minutes to obtain a thickness of 10 μm. A hydrophilic polymer layer comprising a polyvinyl alcohol coating film was formed to obtain a laminate.

(Extension process)
The laminate obtained above was stretched by a roll-to-roll at 160 ° C. in the longitudinal direction (MD direction) at a stretch ratio of 2 to obtain a stretched laminate.

(Dyeing process)
The stretched laminate obtained above was immersed in an iodine solution (mass ratio: iodine / potassium iodide / water = 1/10/100) at 30 ° C. for 60 seconds while maintaining the tension. Then, drying was performed for 4 minutes at 60 degreeC, and polarizing plate PL13 was obtained. In addition, the thickness of the base material layer in obtained PL13 was 40 micrometers. The thickness of the hydrophilic polymer layer (after stretching) in the polarizing plate PL13 was 3 μm.

<Evaluation of properties of polarizing plate>
(Curl evaluation)
The curl was measured by using the curl measurement template of Method A in “Measurement Method of Curling of Photographic Film” of JIS K-7619-1988, and the sample was placed in an environment of 25 ° C. and 60% RH for 10 hours. Measurements were made after conditioning. The difference ΔC = | C ₁ −C ₂ | was calculated by setting the curl value at 23 ° C. and 55% RH as C ₁ and the curl value at 40 ° C. and 20% RH as C ₂ . The results are shown in Table 1 below.

(Elastic modulus evaluation)
The following evaluation was performed using a Tensilon tester (ORIENTEC, RTC-1225A).

Each polarizing plate was cut out at 120 mm (length) × 10 mm (width), then the base material layer was peeled off to each layer, and the upper and lower sides were sandwiched between chucks of 100 mm (10 mm above and below the grip allowance), and 100 mm / Measurement was performed three times in each of the MD direction and the TD direction at a pulling rate of min, and the average value was calculated. Then, the elastic modulus of the base material layer on the side of the hydrophilic polymer layer is denoted by Ea, and the elastic modulus of the base material layer on the side opposite to the hydrophilic polymer layer is denoted by Eb, and the difference ΔE = | Ea−Eb | (MPa) was calculated. Further, the elastic moduli Ea and Eb in the environment of 23 ° C. and 55% RH are Ea ₁ and Eb ₁ , respectively, and the elastic moduli Ea and Eb in the environment of 40 ° C. and 20% RH are Ea ₂ and Eb ₂ , respectively. Differences ΔEa = | Ea ₁ −Ea ₂ | and ΔEb = | Eb ₁ −Eb ₂ | were calculated. These results are shown in Table 1 below <Evaluation of liquid crystal display device>
42-inch television LEDREGZA42RE1 made by LG Electronics, which is an IPS-type liquid crystal display device, is peeled off from the previously bonded polarizing plate, and any of the polarizing plates PL1 to PL12 produced above is bonded in advance. Were bonded so that the absorption axis was directed in the same direction, and liquid crystal display devices were respectively produced. One surface of Konica Minolta Op KC4UY manufactured by Konica Minolta Opto was saponified, and the surface of the polarizing plate opposite to the surface on which the base material layer of the hydrophilic polymer layer was formed was subjected to the saponification surface. Pasted together. And when bonding a polarizing plate to a liquid crystal display device, it bonded together using the adhesive so that Konica Minolta tack KC4UY might be located in the liquid crystal panel side.

After that, the display device is left in an environment of 23 ° C. and 55% RH for 2 hours, the power source (backlight) is turned on, and the display unevenness and light leakage after 12 hours and 24 hours are displayed in black on the screen. The following criteria were used for the evaluation. The results are shown in Table 1 below.

(Display unevenness)
Image display is uniform: ◎
Image display is almost uniform: ○
There is unevenness in the center and surroundings:
There is clear unevenness in the center and surrounding area: ×
(Light leakage)
No light leakage: ◎
There is slight light leakage: ○
Some light leaks and feels bright: △
There is light leakage and feels dazzling: ×

As is apparent from the results shown in Table 1, it can be seen that the liquid crystal display device used in the configuration of the present invention can obtain uniform image quality without unevenness and light leakage.

Claims

A polarizing plate having a stretched laminate in which a laminate of a hydrophilic polymer layer and a base material layer containing a thermoplastic resin is stretched, and a dichroic substance is adsorbed on the hydrophilic polymer layer, ,
The difference ΔC = | C 1 −C 2 | between the curl C 1 in the environment of 23 ° C. and 55% RH and the curl C 2 in the environment of 40 ° C. and 20% RH satisfies ΔC ≦ 80 [1 / m]. ,Polarizer.
The polarizing plate according to claim 1, wherein the base material layer contains at least two kinds of thermoplastic resins.
The polarizing plate according to claim 1 or 2, wherein the hydrophilic polymer layer has a thickness of 0.5 to 30 µm.
The thermoplastic resin contained in the base material layer is made of an acrylic resin, a styrene resin, a cycloolefin resin, a cellulose resin, a polypropylene resin, a polyester resin, or a combination thereof. The polarizing plate of any one.
The base material layer is at least
A first base material layer containing a first thermoplastic resin;
A second substrate layer comprising a second thermoplastic resin, disposed on the opposite side of the hydrophilic polymer layer with respect to the first substrate layer;
The polarizing plate according to any one of claims 1 to 4, which comprises:
The difference ΔE = | Ea−Eb | (MPa) between the elastic modulus Ea of the first base material layer and the elastic modulus Eb of the second base material layer satisfies ΔE ≦ 3000 [MPa], and
Differences ΔEa = | Ea 1 −Ea 2 | and ΔEb between the elastic moduli Ea 1 and Eb 1 in a 23 ° C. and 55% RH environment and the elastic moduli Ea 2 and Eb 2 in a 40 ° C. and 20% RH environment, respectively. 6. The polarizing plate according to claim 5, wherein = | Eb 1 -Eb 2 | satisfies ΔEa, ΔEb ≦ 2000 [MPa].
The polarizing plate according to any one of claims 1 to 6, wherein the stretched laminate has a thickness of 10 to 100 µm.
The polarizing plate according to any one of claims 1 to 7, wherein the hydrophilic polymer layer contains polyvinyl alcohol as a hydrophilic polymer.
The polarizing plate according to any one of claims 1 to 8, wherein the dichroic substance is iodine.
A method for producing a polarizing plate according to any one of claims 1 to 9,
The manufacturing method including the process of forming the said base material layer into a film by a solution casting method.
The manufacturing method of Claim 10 which further includes the process of apply | coating the solution containing hydrophilic polymer to one surface of the said base material layer formed into a film, and making it dry and obtaining a laminated body.
The production method according to claim 11, further comprising a step of stretching the laminate at a stretching ratio of 2 to 10 times.
A display device comprising the polarizing plate according to any one of claims 1 to 9, or the polarizing plate produced by the production method according to any one of claims 10 to 12.
The display device according to claim 13, which is an IPS mode type liquid crystal display device.