JPWO2013133276A1 - Polarizing plate and display device using the same - Google Patents

Abstract

Disclosed is a polarizing plate that is excellent in durability (particularly durability under high humidity conditions) and can be produced at a high production yield. One embodiment of the present invention includes a polarizer, a first polarizing plate protective film disposed on one surface of the polarizer, and a surface of the first polarizing plate protective film opposite to the polarizer. And a hard coat layer disposed on the polarizing plate. And the polarizing plate which concerns on this form has a film thickness of a polarizer of 0.5-5.0 micrometers, and the bending rigidity in 25 degreeC55% RH of a 1st polarizing plate protective film is 0.0002-0.025 mPa. -It has a feature in that it is m3.

Description

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

  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.

  Here, as a method of the liquid crystal display device, a so-called TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type, and the like are well known. Such a liquid crystal display device 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.

  One of important constituent members of a liquid crystal display device 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. Here, as one type of polarizer constituting the polarizing plate, after applying a hydrophilic polymer such as an aqueous polyvinyl alcohol solution on a substrate, a dichroic substance such as iodine is applied to the hydrophilic polymer. A so-called coating type polarizer manufactured by adsorption is known.

  Conventionally, as a manufacturing method of a polarizing plate provided with a coating type polarizer, a polyvinyl alcohol aqueous solution is applied on a substrate such as a PET film, and the obtained laminate is stretched to adsorb iodine, thereby polarizing plate protective film. A method has been proposed in which bonding is performed via an adhesive and the substrate is further peeled and removed (see, for example, Patent Documents 1 and 2). According to the disclosure of these patent documents, the contraction stress of the polarizer is reduced by the configuration as described above, and problems such as the curling of the polarizing plate and the deterioration of the display quality of the display element due to the contraction of the polarizer occur. It is said that can be prevented.

  On the other hand, on the viewing side of the polarizing plate used on the display surface side of the liquid crystal display device, a hard coat layer mainly composed of an ultraviolet curable resin composition may be provided for the purpose of scratch resistance and durability of the display surface. It is common. In addition, a similar hard coat layer may be provided on the backlight side of the backlight side polarizing plate of the display device in order to prevent the heat from the backlight from acting on the polarizing plate protective film to cause curling or the like.

JP 2011-81399 A JP 2011-128486 A

  The present inventor has found that when a polarizing plate having a hard coat layer is constituted by the technique described in the above-mentioned patent document, there is a problem that the production yield at the time of producing the polarizing plate is lowered. Further, it has also been found that the polarizing plate disclosed in the patent document is not sufficiently durable particularly under high humidity conditions.

  Accordingly, an object of the present invention is to provide a polarizing plate that is excellent in durability (particularly, durability under high humidity conditions) and can be produced at a high production yield.

  The present inventor has intensively studied in view of the above problems. As a result, in constructing a thinned polarizing plate, the above problem is obtained by laminating a first polarizing plate protective film having a predetermined bending rigidity value and having a hard coat layer disposed on the surface thereof with a polarizer. Has been found to be solved, and the present invention has been completed.

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

1. A polarizer,
A first polarizing plate protective film disposed on one surface of the polarizer;
A hard coat layer disposed on a surface opposite to the polarizer of the first polarizing plate protective film;
A polarizing plate comprising
The polarizer has a thickness of 0.5 to 5.0 μm,
A polarizing plate having a flexural rigidity of 0.0002 to 0.025 mPa · m ³ at 25 ° C. and 55% RH of the first polarizing plate protective film;
2. 2. The polarizing plate according to 1 above, wherein the film thickness of the first polarizing plate protective film is 15 to 35 μm;
3. The polarizing plate according to 1 or 2 above, wherein the first polarizing plate protective film contains a cellulose ester resin;
4). The polarizing plate according to any one of 1 to 3, wherein the polarizer contains polyvinyl alcohol;
5. The polarizing plate according to any one of 1 to 4 above, wherein a second polarizing plate protective film is disposed on the surface of the polarizer opposite to the first polarizing plate protective film;
6). Applying a solution containing a hydrophilic polymer to the surface of the stretching film and drying to form a hydrophilic polymer layer to obtain a first laminate;
Stretching the first laminate to obtain a stretched laminate;
Adsorbing a dichroic substance on the hydrophilic polymer layer;
A second laminate in which a hard coat layer is disposed on one surface of a first polarizing plate protective film having a flexural rigidity at 25 ° C. and 55% RH of 0.0002 to 0.025 mPa · m ³ , A step of bonding to the stretched laminate so that the polarizing plate protective film of 1 and the hydrophilic polymer layer face each other;
A method for producing a polarizing plate, comprising:
7). The production method according to 6 above, further comprising a step of peeling and removing the stretching film;
8). After the step of peeling / removing the stretching film, the method further includes a step of bonding a second polarizing plate protective film to the surface of the hydrophilic polymer layer opposite to the first polarizing plate protective film. And the production method according to 7 above;
9. The display apparatus provided with the polarizing plate of any one of said 1-5, or the polarizing plate manufactured by the manufacturing method of any one of said 6-8.

It is a schematic diagram for demonstrating the process flow at the time of producing the polarizing plate which concerns on this invention.

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

One form of this invention was arrange | positioned on the surface on the opposite side to the polarizer of the polarizer, the 1st polarizing plate protective film arrange | positioned on one surface of a polarizer, and the 1st polarizing plate protective film. The present invention relates to a polarizing plate including a hard coat layer. And the polarizing plate which concerns on this form has a film thickness of a polarizer of 0.5-5.0 micrometers, and the bending rigidity in 25 degreeC55% RH of a 1st polarizing plate protective film is 0.0002-0.025 mPa. · m characterized in that the point ^3. ADVANTAGE OF THE INVENTION According to this invention, the polarizing plate which is excellent in durability (especially durability under high-humidity conditions), and can be produced with a high production yield is provided.

≪Polarizing plate≫
Hereinafter, the polarizing plate according to the present embodiment will be described in more detail.

[Polarizer]
The polarizing plate according to this embodiment includes a polarizer as a main component. A polarizer is an element that allows only light having a plane of polarization in a certain direction to pass through, and usually has a configuration in which a dichroic substance is adsorbed on a substrate made of a hydrophilic polymer.

  Although there is no restriction | limiting in particular about the hydrophilic polymer which comprises a polarizer, 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.

  Although there is no restriction | limiting in particular also about the specific structure of the dichroic substance adsorb | sucked by the hydrophilic polymer in a polarizer, For example, an iodine, an organic dye, etc. are mentioned. 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. There is no restriction | limiting in particular also about the adsorption amount of the dichroic substance to the hydrophilic polymer in a polarizer, It is possible to set suitably with reference to conventionally well-known knowledge.

  The polarizer 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 polarizing plate according to this embodiment has one characteristic in that the thickness of the polarizer is 0.5 to 5.0 μm. If the thickness of the polarizer is less than 0.5 μm, the production is difficult. On the other hand, if the thickness of the polarizer exceeds 5.0 μm, there is a problem that it is not possible to sufficiently meet the demand for thinning. In addition, there is a problem that the contraction stress of the polarizer increases and the curling of the obtained polarizing plate increases. In addition, the film thickness of a polarizer becomes like this. Preferably it is 0.5-3.0 micrometers, More preferably, it is 0.5-1.5 micrometers.

[First polarizing plate protective film]
The polarizing plate according to this embodiment has a polarizing plate protective film (first polarizing plate protective film) on one surface of the polarizer. And the hard-coat (HC) layer is arrange | positioned at the surface on the opposite side to the polarizer of this polarizing plate protective film (1st polarizing plate protective film). Here, as will be described later, the polarizing plate according to this embodiment may have a polarizing plate protective film on both surfaces of the polarizer. Therefore, for the sake of convenience, the polarizing plate protective film (the above-described film in which the hard coat layer is disposed on the surface opposite to the polarizer), which is an essential component in the present invention, is referred to as “first polarizing plate protective film”. The polarizing plate protective film which is an optional component in the present invention is referred to as a “second polarizing plate protective film”. However, the ordinal numbers “first” and “second” are given only for the purpose of distinguishing the two polarizing plate protective films for convenience, and the expressions “first” and “second” There is no particular meaning in itself.

  For the configuration of the hard coat layer, conventionally known knowledge can be referred to as appropriate. The hard coat (HC) layer preferably contains an ultraviolet absorber, and the specific form of the ultraviolet absorber is not particularly limited.

<First polarizing plate protective film>
As a 1st polarizing plate protective film, what contains 1 type (s) or 2 or more types, such as a cellulose resin, acrylic resin, cyclic olefin resin, and polycarbonate-type resin, is used, for example. If it is a film containing these resin, it will be excellent in various characteristics, such as transparency required for a polarizing plate protective film, heat resistance, and moisture resistance. Especially, in preferable embodiment, a 1st polarizing plate protective film contains a cellulose resin. Examples of the cellulose resin include cellulose ester resins and cellulose ether resins, and cellulose ester resins are particularly preferable.

  As the cellulose ester resin used in the present invention, those satisfying the following mathematical expressions (1) and (2) are preferable.

  In the formula, A is the substitution degree of the acetyl group, and B is the substitution degree of the propionyl group or butyryl group. Those satisfying the above two formulas can provide a film exhibiting excellent physical properties and optical properties that meet the object of the present invention.

  Of these, triacetyl cellulose and cellulose acetate propionate are particularly preferably used. In cellulose acetate propionate, 1.0 ≦ A ≦ 2.5, and preferably 0.1 ≦ B ≦ 1.5 and 2.0 ≦ A + B ≦ 3.0.

  If the substitution degree of the acyl group is too low, there will be more unreacted parts with respect to the hydroxyl groups of the pyranose ring constituting the skeleton of the cellulose resin. The ability to protect the polarizer as a film may decrease, which is not preferable.

  The portion that is not substituted with an acyl group is usually present as a hydroxyl group. These can be synthesized by known methods. Moreover, the substitution degree of an 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 more preferably in the range of 100,000 to 240,000, 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.

  Although there is no restriction | limiting in particular also 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” here means 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 a polarizing plate protective 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 is not particularly limited as long as it can be formed into a film alone. Specifically, the number average molecular weight Mn may be in the range of 30,000 to 300,000 (polystyrene conversion), and more preferably. 50,000 to 200,000 are used. If the molecular weight is too small, the film becomes brittle, 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.

(Physical properties and optical properties of the first polarizing plate protective film)
In the present invention, the bending stiffness (D) at 25 ° C. and 55% RH of the first polarizing plate protective film is 0.0002 to 0.025 mPa · m ³ , preferably 0.002 to 0.012 mPa · m ³ . Yes, more preferably 0.004 to 0.012 mPa · m ³ , and particularly preferably 0.006 to 0.010 mPa · m ³ . The value of the bending stiffness of the first polarizing plate protective film is within such a range, which contributes to the improvement of the durability of the polarizing plate (particularly, durability under high humidity conditions). Conceivable.

  Although its mechanism of operation is not clear, as shown in FIG. 1, when the polarizing plate 30 is manufactured, the polarizing plate 30 is formed on the polarizer side (the upper surface side shown in FIG. 1) of the base material 32 having the coating type polarizer, and on the other side. When the first polarizing plate protective film 24 having a hard coat layer is supported by the backup roll 10 and passed between the laminate roll 20 and bonded, the film is placed at the holding angle (R) of the backup roll 10. In order to conform, it is necessary to apply tension due to the hardness of the hard coat layer, which usually has a pencil hardness of at least 1H. At this time, it is presumed that the residual stress generated by the tension is reduced by making the value of the bending rigidity of the first polarizing plate protective film 24 appropriate and facilitating along the R of the backup roll 10. Furthermore, since it is easy to follow along R of the backup roll 10, it is thought that air entrainment is also reduced, mixing of air bubbles is suppressed, the surface shape after bonding can be smoothed, and productivity is improved.

In this specification, the value (D) of the “bending rigidity” of the first polarizing plate protective film is the value of the bending rigidity (D _M ) in the first direction (for example, MD direction) of the film at 25 ° C. and 55% RH. ) And a bending stiffness value (D _T ) in a second direction (for example, TD direction) perpendicular to the first direction of the film under the same conditions. Here, _DM is the film thickness h [m], the film Poisson's ratio is ν [-], and the tensile modulus of the film in the first direction at 25 ° C. and 55% RH is E _M [mPa ], The following formula (3):

Is calculated by Similarly, _DT is expressed as follows using h [m] and ν [−] when the tensile elastic modulus in the second direction at 25 ° C. and 55% RH of the film is E _T [mPa]. Formula (4):

Is calculated by In this case, _{E M} of the first polarizing plate protective film, was cut out of a predetermined width along the MD direction from the film, in conformity with JIS K7161, a tensile the test piece at 25 ° C. 55 ° C. RH It can be calculated from linear regression of a stress-strain curve obtained by stretching in the MD direction under the condition of a speed of 300 mm / min. Also, E _T, using a test piece cut out to a predetermined width along the TD direction of a film, can be calculated in a similar manner. More specifically, for example, a value measured according to a method of measuring a tensile elastic modulus described in Examples described later can be adopted. The Poisson's ratio ν is a value (dimensionalless number) determined by the material of the first polarizing plate protective film. When the material of the first polarizing plate protective film is a cellulose ester resin, it is usually a value of ν. 0.4 can be adopted.

In the above, the bending rigidity (D _M ) in the first direction calculated from the tensile modulus (E _M ) in the first direction (MD direction) and the tensile modulus (E _T ) in the second direction (TD direction). The method of calculating the value of the bending stiffness of the film as the average value of the bending stiffness (D _T ) in the second direction calculated from the above has been described, but the tensile modulus (E _M ) in the first direction (MD direction) and Using the average value of the tensile modulus (E _T ) in the second direction (TD direction) as the value of the elastic modulus of the film, the value of the bending stiffness of the film is similarly determined from the above formula (3) or formula (4). It may be calculated.

  In order to control the value of the bending stiffness of the first polarizing plate protective film to a value within the above-described range, for example, the bending stiffness can be adjusted by adjusting the film thickness of the first polarizing plate protective film. As the film thickness increases, the bending rigidity increases, and as the film thickness decreases, the bending rigidity can be reduced.

  Although there is no restriction | limiting in particular about the film thickness (h) of a 1st polarizing plate protective film, Preferably it is 15-35 micrometers, Most preferably, it is 20-30 micrometers. According to the present invention, even when the polarizing plate is constituted by using such a thin polarizing plate protective film (first polarizing plate protective film), durability (particularly, durability under high humidity conditions) In addition, a polarizing plate that can be produced at a high production yield is provided.

Moisture permeability of the first polarizing plate protective film according to the present embodiment, 40 ° C., preferably 10~1200g ^/ m 2 · 24h at 90% RH, preferably more ^{20~1000g / m 2 · 24h, 20~850g} / m ² · 24 h is particularly preferable. The moisture permeability can be measured according to the method described in JIS Z 0208.

  The breaking elongation of the first polarizing plate protective film according to this embodiment is preferably 10 to 80%, and more preferably 20 to 50%.

  The visible light transmittance of the first polarizing plate protective film according to this embodiment is preferably 90% or more, and more preferably 93% or more.

  The haze of the first polarizing plate protective film according to this embodiment is preferably less than 1%, and particularly preferably 0 to 0.1%.

  There is no restriction | limiting in particular about the retardation value of the 1st polarizing plate protective film which concerns on this form, What is necessary is just to set suitably according to the use of a polarizing plate. About the retardation value of a 1st polarizing plate protective film, the conditions of the extending | stretching process at the time of preparation of a 1st polarizing plate protective film, and addition of the retardation regulator which may be added to a 1st polarizing plate protective film It can be controlled by adjusting the amount or the like.

<Additives that can be included in the first polarizing plate protective film>
Unless the function as a polarizing plate protective film is impaired, the 1st polarizing plate protective film may be comprised including additives other than the resin component mentioned above. However, the content of the resin component in the first polarizing plate protective film is preferably 60 to 95% by weight and more preferably 70 to 90% by weight with respect to 100% by weight of the total amount of the first polarizing plate protective film. %. Hereinafter, although the example of the additive which may be contained in a 1st polarizing plate protective film is demonstrated, it is not limited only to the following form. Examples of the additive include a plasticizer, a sugar ester compound, a retardation adjusting agent, an ultraviolet absorber, an infrared absorber, a matting agent (fine particles), and a colorant.

(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.

  In 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 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 an aromatic ring (6 to 14 carbon atoms) or a dicarboxylic acid having a linear or branched alkylene group or cycloalkylene group (both having 2 to 6 carbon atoms) and a carbon number. It is an alternating copolymer obtained by alternating copolymerization with 2-6 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. Moreover, you may seal both ends with the monocarboxylic acid which has an aromatic ring (C6-C14).

  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.

  Below, the aromatic polyester compound which can be used in this invention is illustrated.

  The first polarizing plate protective film 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 plasticizer is preferably a polyhydric alcohol ester plasticizer.

  The polyhydric alcohol ester plasticizer is a plasticizer comprising an ester of a dihydric or higher aliphatic polyhydric alcohol and a monocarboxylic acid, and preferably has an aromatic ring or a cycloalkyl ring in the molecule. Preferably it is a 2-20 valent aliphatic polyhydric alcohol ester.

  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).

  As the polyhydric alcohol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are particularly 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.

  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.

  Below, the specific compound of a polyhydric alcohol ester is illustrated.

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

  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 acetyl trimethyl citrate, acetyl triethyl citrate, and acetyl tributyl 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 divalent or higher, preferably divalent to 20 valent polyvalent carboxylic acid and alcohol. The aliphatic polyvalent carboxylic acid is preferably 2 to 20 valent, and in the case of an aromatic polyvalent carboxylic acid or an alicyclic polyvalent carboxylic acid, it is preferably 3 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 the polyvalent carboxylic acid include trivalent or higher aromatic polyvalent carboxylic acids such as trimellitic acid, trimesic acid, and pyromellitic acid or derivatives thereof, succinic acid, adipic acid, azelaic acid, sebacic acid, oxalic acid, fumaric acid. An aliphatic polyvalent carboxylic acid such as acid, maleic acid and tetrahydrophthalic 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.

  There is no restriction | limiting in particular as alcohol used for a polyhydric carboxylic acid ester compound, Well-known alcohol and phenols can be used. The alcohol used may be one kind or a mixture of two or more kinds.

  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. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10.

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

  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 acid value of the polyvalent carboxylic acid ester compound 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.

  In addition, an acid value means the milligram number of potassium hydroxide required in order to neutralize the acid (carboxy group which exists in a sample) contained in 1g of samples. The acid value is measured according to JIS K0070.

  Particularly preferred polyvalent carboxylic acid ester compounds include triethyl citrate, tributyl citrate, acetyl triethyl citrate (ATEC), acetyl tributyl citrate (ATBC), benzoyl tributyl citrate, acetyl triphenyl citrate, acetyl tribenzyl citrate. Rate, dibutyl tartrate, diacetyl dibutyl tartrate, tributyl trimellitic acid, tetrabutyl pyromellitic acid and the like.

  It is preferable that a plasticizer is contained in the quantity of 0.1-30 mass% with respect to 100 mass% of whole quantity of a 1st polarizing plate protective film, More preferably, it is 2-20 mass%.

(Sugar ester compound)
Since the first polarizing plate protective film further includes a sugar ester compound in addition to the resin component, hydrolysis of the resin component is prevented, and thus the water resistance of the film can be improved. This effect is particularly prominent when a cellulose resin (particularly, a cellulose ester resin) is used as the resin component.

  As an example of the 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 the monosaccharide or disaccharide residue, 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-(O—C (═O) —R) groups (1) are important is important, and 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 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.

  Although the structural example of the compound which has a monosaccharide residue represented by General formula (5) below is shown, this invention is not limited to these specific examples.

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

  Although the structural example of the compound which has a disaccharide residue represented by General formula (5) below is shown, this invention is not limited to these specific examples.

  In 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. The total number of — (O—C (═O) —R) groups. 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 as or different from each other.

  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.

  It is preferable that a sugar ester compound is contained in the quantity of 0.1-30 mass% with respect to 100 mass% of whole quantity of a 1st polarizing plate protective film, More preferably, it is 2-20 mass%.

(Retardation adjuster)
The first polarizing plate protective film 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.

  Another example of the retardation adjusting agent is a compound disclosed in Japanese Patent Application Laid-Open No. 2010-163482 as the general formula (I). Specific examples of the general formula (I) are disclosed in paragraphs “0052” to “0058” of the publication. Moreover, the compound currently disclosed by Unexamined-Japanese-Patent No. 2010-163483 as general formula (I) can also be used as a retardation regulator similarly. Specific examples of the general formula (I) are disclosed in paragraphs “0054” to “0068” of the publication.

  It is preferable that a retardation regulator is contained in the quantity of 0.1-30 mass% with respect to 100 mass% of whole quantity of a 1st polarizing plate protective film, More preferably, it is 2-20 mass%.

(UV absorber)
The 1st polarizing plate protective film can also contain a 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 the 1st polarizing plate protective film 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 Preferred are benzotriazole ultraviolet absorbers, benzophenone ultraviolet absorbers, and triazine ultraviolet absorbers, and particularly preferred are benzotriazole ultraviolet absorbers and benzophenone ultraviolet 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.

  It is preferable that an ultraviolet absorber is contained in the quantity of 0.1-15 mass% with respect to 100 mass% of whole quantity of a 1st polarizing plate protective film, and it is more contained in the quantity of 1-10 mass%. preferable.

(Infrared absorber)
The first polarizing plate protective film may contain 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 absorbing agent, it is preferable to use an infrared absorbing dye or an infrared absorbing pigment, and it is particularly preferable to use an infrared absorbing dye.

  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. The infrared absorbing dye is described in Coloring Materials, 61 [4] 215-226 (1988), and Chemical Industry, 43-53 (1986, May).

  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 first polarizing plate protective film. preferable.

(Matting agent (fine particles))
The first polarizing plate protective film has, for example, silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, kaolin, talc, calcined calcium silicate, hydrated calcium silicate, and silicic acid in order to improve handling properties. It is preferable to contain inorganic fine particles such as aluminum, magnesium silicate 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 a preferable average particle size is 0.1 to 2 μm, more preferably 0.2 to 0. .6 μm. Thereby, the unevenness | corrugation about 0.1-1.0 micrometer high can be formed in the film surface, and this can give appropriate slipperiness to the film surface.

  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 matting agent (fine particles) is preferably contained in an amount of 0.01 to 5% by mass and in an amount of 0.1 to 3% by mass with respect to 100% by mass of the total amount of the first polarizing plate protective film. More preferably.

(Coloring agent)
The first polarizing plate protective film 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, and in an amount of 0.1 to 3% by mass with respect to 100% by mass of the total amount of the first polarizing plate protective film. More preferred.

<Hard coat (HC) layer>
As described above, the hard coat (HC) layer is disposed on one surface of the first polarizing plate protective film (the surface opposite to the polarizer of the film). Depending on the arrangement of the hard coat layer, functions such as durability and impact resistance are imparted to the polarizing plate.

  In recent years, display devices have been improved in definition, and on the other hand, in order to improve productivity, both improvement in production speed and improvement in production yield are required. If the production rate is increased to achieve this, scratches are likely to occur on the surface during conveyance of the member, but if a hard coat layer is disposed on the surface of the polarizing plate protective film, such scratches are prevented from occurring. There is an advantage that. In addition, due to the widespread use of portable devices with touch panels, fillers and adhesives (with a refractive index of a plastic base material) are used between them for the purpose of reducing interface reflection at the interface between the display device and the touch panel member and improving transmittance. Equivalent layers) are also placed, but the hard coat layer is placed on the most visible side of the liquid crystal display device, which improves the wettability of such fillers and adhesives. There is also an advantage that the layers composed of these can be arranged uniformly.

  In view of the function of the hard coat layer described above, the polarizing plate according to the present invention is used on the viewing side of a display panel such as a liquid crystal panel or an organic EL panel, and the hard coat layer is the most essential component. It is preferable to be arranged and used so as to be positioned on the viewing side.

  In the present invention, the “hard coat layer” refers to a film having a pencil hardness of H to 8H. Especially preferably, it is H-5H. The pencil hardness is adjusted according to the pencil hardness evaluation method stipulated by JIS K 5400 using a test pencil stipulated by JIS S6006 after the prepared hard coat layer is conditioned for 2 hours at a temperature of 25 ° C. and 60% RH. It is a measured value.

(Polyfunctional acrylate)
As the composition for forming the hard coat layer, an actinic ray curable resin that is generally cured by actinic rays such as ultraviolet rays is used, but it is preferable to contain a polyfunctional acrylate as such an actinic ray curable resin. . This polyfunctional acrylate is preferably selected from the group consisting of pentaerythritol polyfunctional acrylate, dipentaerythritol polyfunctional acrylate, pentaerythritol polyfunctional methacrylate, and dipentaerythritol polyfunctional methacrylate. Here, the polyfunctional acrylate is a compound having two or more acryloyloxy groups and / or methacryloyloxy groups in the molecule.

  The addition amount of the actinic ray curable resin is preferably 15% by mass or more and less than 70% by mass in the solid content of the composition for forming a hard coat layer.

  In order to accelerate the curing of the actinic ray curable resin, a photopolymerization initiator and an acrylic compound having at least two polymerizable unsaturated bonds in the molecule are contained in a mass ratio of 20: 100 to 0.01: 100. It is preferable.

  Specific examples of the photopolymerization initiator include acetophenone, benzophenone, hydroxybenzophenone, Michler's ketone, α-amyloxime ester, thioxanthone, and derivatives thereof, but are not particularly limited thereto.

A binder such as a known thermoplastic resin, thermosetting resin or hydrophilic resin such as gelatin may be mixed with the actinic ray curable resin for use in the hard coat layer. These resins preferably have a polar group in the molecule. Examples of the polar _{group, -COOM, -OH, -NR 2,} -NR 3 X, -SO 3 M, -OSO 3 M, -PO 3 M 2, -OPO 3 M ( wherein, M represents a hydrogen atom, an alkali A metal or an ammonium group, X represents an acid that forms an amine salt, and R represents a hydrogen atom or an alkyl group).

  Commercially available actinic radiation curable resins that can be used include Adekaoptomer KR / BY series: KR-400, KR-410, KR-550, KR-566, KR-567, BY-320B (Asahi Denka Co., Ltd.) ); Koeihard A-101-KK, A-101-WS, C-302, C-401-N, C-501, M-101, M-102, T-102, D-102, NS- 101, FT-102Q8, MAG-1-P20, AG-106, M-101-C (manufactured by Guangei Chemical Co., Ltd.); Seika Beam PHC2210 (S), PHC X-9 (K-3), PHC2213, DP- 10, DP-20, DP-30, P1000, P1100, P1200, P1300, P1400, P1500, P1600, SCR900 (manufactured by Dainichi Seika Kogyo Co., Ltd.); KR 7033, KRM 7039, KRM 7130, KRM 7131, UVECRYL 29201, UVECRYL 29202 (manufactured by Daicel UC Corporation); RC-5015, RC-5016, RC-5020, RC-5031, RC-5100, RC-5102, RC-5120, RC-5122, RC-5152, RC-5171, RC-5180, RC-5181 (Dainippon Ink Chemical Co., Ltd.); 340 clear (manufactured by China Paint Co., Ltd.); Sunrad H-601, RC-750, RC-700, RC-600, RC-500, RC-611, RC-612 (manufactured by Sanyo Chemical Industries); SP -1509, SP-1507 (manufactured by Showa Polymer Co., Ltd.); RCC-15C (manufactured by Grace Japan Co., Ltd.), Aronix M-6100, M-8030, M-8060 (manufactured by Toagosei Co., Ltd.); B420 (manufactured by Shin-Nakamura Chemical Co., Ltd.) and the like.

  Further, the hard coat layer may contain fine particles of an inorganic compound or an organic compound in order to adjust the scratch resistance, slipperiness and refractive index.

  The average particle size of these fine particle powders is preferably 0.01 to 5 μm, more preferably 0.1 to 5.0 μm, and particularly preferably 0.1 to 4.0 μm. Further, it is preferable to contain two or more kinds of fine particles having different particle diameters. It is preferable to mix | blend the ratio of content of actinic-light curable resin and microparticles | fine-particles so that microparticles may be 0.1-30 mass parts with respect to 100 mass parts of resin.

  In order to increase the heat resistance of the hard coat layer, an antioxidant that does not inhibit the photocuring reaction can be selected and used. Examples include hindered phenol derivatives, thiopropionic acid derivatives, phosphite derivatives, and the like. Specifically, for example, 4,4′-thiobis (6-tert-3-methylphenol), 4,4′-butylidenebis (6-tert-butyl-3-methylphenol), 1,3,5-tris (3,5-di-tert-butyl-4-hydroxybenzyl) isocyanurate, 2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) mesitylene, di-octadecyl-4- Examples include hydroxy-3,5-di-tert-butylbenzyl phosphate.

  These hard coat layers can be coated by a known method such as a gravure coater, a dip coater, a reverse coater, a wire bar coater, a die coater, or an ink jet method. After application, it is heat-dried and UV-cured. The coating amount is suitably 0.1 to 40 μm, preferably 0.5 to 30 μm, as the wet film thickness. Moreover, as a dry film thickness, it is an average film thickness of 0.1-30 micrometers, Preferably it is 1-20 micrometers.

  The hard coat layer forming composition (coating solution) may contain a solvent, or may be appropriately contained and diluted as necessary. Propylene glycol monoalkyl ether (1 to 4 carbon atoms of the alkyl group) or propylene glycol monoalkyl ether acetate ester (1 to 4 carbon atoms of the alkyl group) is 5% by mass or more, more preferably 5 to 80%. It is preferable to use the organic solvent containing at least mass%.

  The hard coat layer has a center line average roughness (Ra) defined by JIS B 0601 of 0.001 to 0.1 μm, or a fine hard coat layer and Ra is adjusted to 0.1 to 1 μm. An antiglare hard coat layer may also be used. The center line average roughness (Ra) is preferably measured by an optical interference type surface roughness measuring instrument, and can be measured, for example, using a non-contact surface fine shape measuring device WYKO NT-2000 manufactured by WYKO.

  Further, the hard coat layer preferably contains a silicone surfactant or a polyoxyether compound. As the silicone surfactant, polyether-modified silicone is preferable. Specifically, BYK-UV3500, BYK-UV3510, BYK-333, BYK-331, BYK-337 (manufactured by BYK Japan), TSF4440, TSF4445, TSF4446, TSF4452, TSF4460 (GE Toshiba Silicone), KF-351, KF-351A, KF-352, KF-353, KF-354, KF-355, KF-615, KF-618, KF-945, KF- 6004 (polyether-modified silicone oil; manufactured by Shin-Etsu Chemical Co., Ltd.) and the like are exemplified, but not limited thereto.

  Of the polyoxyether compounds, the polyoxyethylene oleyl ether compound is preferable, and is generally a compound represented by the general formula (α).

In the formula, n represents 2 to 40.

  The average addition number (n) of ethylene oxide with respect to the oleyl part is 2 to 40, preferably 2 to 10, more preferably 2 to 9, and further preferably 2 to 8. The compound of the general formula (α) can be obtained by reacting ethylene oxide with oleyl alcohol.

  Specific products include Emulgen 404 (polyoxyethylene (4) oleyl ether), Emulgen 408 (polyoxyethylene (8) oleyl ether), Emulgen 409P (polyoxyethylene (9) oleyl ether), Emulgen 420 (polyoxy) Ethylene (13) oleyl ether), Emulgen 430 (polyoxyethylene (30) oleyl ether) or more, Kao Corporation, NOFLEEAO-9905 (polyoxyethylene (5) oleyl ether) manufactured by NOF Corporation.

  Note that () represents the number n. A nonionic polyoxyether compound may be used independently and may use 2 or more types together.

  These improve applicability | paintability and it is preferable to add these components in 0.01-3 mass% with respect to the solid content component in a coating liquid.

  Further, the hard coat layer may contain a fluorine-siloxane graft polymer.

  The fluorine-siloxane graft polymer refers to a copolymer polymer obtained by grafting polysiloxane containing siloxane and / or organosiloxane alone and / or organopolysiloxane to at least a fluorine-based resin. Examples of commercially available products include ZX-022H, ZX-007C, ZX-049, and ZX-047-D manufactured by Fuji Chemical Industry Co., Ltd. Moreover, you may use these compounds in mixture. Fluorine-siloxane graft polymer should be used in a coating solution that has a mass ratio of actinic ray curable resin to fluorine-siloxane graft polymer: energy-active radiation curable resin = 0.05: 100 to 5.00: 100. To preferred.

  The hard coat layer may have a multilayer structure of two or more layers. One of the layers may be a so-called conductive layer containing, for example, conductive fine particles, a π-conjugated conductive polymer, or an ionic polymer.

  Further, as a color correction filter for various display elements, a color tone adjusting agent (dye or pigment, etc.) having a color tone adjusting function may be included, or an electromagnetic wave blocking agent or an infrared absorbing agent may be added to each function. It is preferable to have it.

  As for the irradiation time for obtaining the necessary irradiation amount of actinic light for ultraviolet irradiation after coating and drying of the hard coat layer, about 0.1 second to 1 minute is preferable, and the curing efficiency or working efficiency of the actinic radiation curable resin From the viewpoint of the above, 0.1 to 10 seconds is more preferable.

Moreover, it is preferable that the illuminance of these actinic ray irradiation parts is 0.05-0.2 W / m < ² >. An adhesive layer or an adhesive layer may be further provided between the first polarizing plate protective film and the hard coat layer. In this case, the film thickness of the adhesive layer or the adhesive layer may be 0.1 μm or less. preferable. Moreover, when forming a hard-coat layer on the surface of the 1st polarizing plate protective film by application | coating, processes, such as a flame treatment, a corona discharge, plasma processing, are given to the surface of a 1st polarizing plate protective film as pre-processing. Also good.

  With respect to the refractive index of the surface of the first polarizing plate protective film layer in contact with the hard coat layer, the refractive index of the hard coat layer surface on the side in contact with the first polarizing plate protective film is in the range of ± 0.02. It is preferable to adjust so that.

[Second polarizing plate protective film]
The polarizing plate according to this embodiment may further have a polarizing plate protective film (second polarizing plate protective film) on the surface of the polarizer opposite to the first polarizing plate protective film.

  There is no restriction | limiting in particular about the specific form of a 2nd polarizing plate protective film. For example, the first polarizing plate protective film described above may be used as it is as the second polarizing plate protective film. The second polarizing plate protective film may be a conventionally known polarizing plate protective film. A commercially available cellulose ester resin film can be used as a conventionally well-known polarizing plate protective film. As a commercially available cellulose ester resin film, for example, Konica Minoltack KC8UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UA, KC4UY, KC4UE, KC8UE, KC8UY-HA, HC8UCYU RHA-NC, KC4UXW-RHA-NC (manufactured by Konica Minolta Advanced Layer Co., Ltd.) and the like are preferably used. Moreover, an acrylic resin film, a cyclic olefin resin film, a polycarbonate resin film, or the like may be used as another conventionally known polarizing plate protective film.

  However, in a preferred embodiment, the second polarizing plate protective film contains a cellulose ester resin. By setting it as such a structure, the advantage that the water resistance of a polarizing plate can be improved is acquired.

  Alternatively, 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 is used as the second polarizing plate protective film. It is also preferable. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348.

[Configuration of polarizing plate]
<Thickness of polarizing plate>
The thickness of the polarizing plate concerning this form becomes like this. Preferably it is 16-80 micrometers, More preferably, it is 20-70 micrometers, More preferably, it is 20-60 micrometers.

  In addition, in addition to each thickness of a polarizer and the 1st and 2nd polarizing plate protective film, in addition to the thickness of a polarizing plate, the thickness of a polarizing plate WHEREIN: When various functional layers mentioned later are arrange | positioned on the surface of a polarizing plate protective film Also includes the thickness of the functional layer.

<Functional layer>
In the polarizing plate according to the present embodiment, the surface of either the first polarizing plate protective film or the second polarizing plate protective film disposed as necessary (preferably, the surface of the first polarizing plate protective film). May be provided with various functional layers (other than the hard coat layer described above) for improving the quality of the display device. In this case, the polarizing plate is used in such a manner that the side on which the functional layer is disposed is located on the side far from the panel of the display device.

  Examples of such a functional layer include antireflection (antireflection (AR)), antiglare (antiglare (AG)), low reflection (low reflection (LR)), dust adhesion prevention, luminance improvement, antistatic, antireflection A conventionally known functional layer having functions such as dirt and a back coat can be used.

  The polarizing plate having the above-described configuration can be configured by further bonding a protective film on one surface and a separate film on the other surface. The protective film and the separate film are used for the purpose of protecting the polarizing plate at the time of shipping the polarizing plate and at the time of product inspection. In this case, the protect film is bonded for the purpose of protecting the surface of the polarizing plate, and is used on the side opposite to the surface where the polarizing plate is bonded to the 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.

≪Production method of polarizing plate≫
There is no restriction | limiting in particular about the manufacturing method of the polarizing plate which concerns on this form, A conventionally well-known knowledge can be referred suitably. However, according to the present invention, a novel manufacturing method is also provided as one of preferable manufacturing methods of the polarizing plate having the above-described configuration. That is, according to another aspect of the present invention, the following steps:
(1) A step of applying a solution containing a hydrophilic polymer on the surface of the stretching film and drying to form a hydrophilic polymer layer to obtain a first laminate;
(2) A step of stretching the first laminate to obtain a stretched laminate;
(3) a step of adsorbing a dichroic substance on the hydrophilic polymer layer;
(4) A second laminate in which a hard coat layer is disposed on one surface of a first polarizing plate protective film having a flexural rigidity at 25 ° C. and 55% RH of 0.0002 to 0.025 mPa · m ^3. A step of bonding to the stretched laminate so that the first polarizing plate protective film and the hydrophilic polymer layer face each other,
The manufacturing method of a polarizing plate containing is provided. Hereinafter, it demonstrates in detail in order of a process.

<Process (1)>
In the step (1), a solution containing a hydrophilic polymer is applied to the surface of the stretching film and dried to form a hydrophilic polymer layer. Thereby, a “first laminate” is obtained. Note that the hydrophilic polymer layer formed in this step functions as a polarizer in the finally obtained polarizing plate. Further, the stretching film is a film only for production that is peeled off and removed before application to the final use, and is not an essential layer for exhibiting the function as a polarizing plate.

  First, a solution containing a hydrophilic polymer is prepared. Here, since the specific form of the hydrophilic polymer is as described above, detailed description thereof is omitted here.

  Examples of the solvent for dissolving the hydrophilic polymer include water, dimethyl sulfoxide, N-methyl-2-pyrrolidone, various glycols and the like, and water is most preferable. When water is used, an organic solvent may be contained. The concentration of the hydrophilic polymer in this solution is usually about 1 to 20% by mass, preferably about 2 to 10% by mass. The hydrophilic polymer solution may contain a plasticizer, a leveling agent such as a surfactant, a dichroic dye, and the like.

  Subsequently, a stretching film is prepared. The stretching film is not particularly limited as long as it is a film that can be uniaxially stretched up to about 5 times in a later step, and various resin films can be used. Specific examples of the stretching film include a polyester resin film and a polyolefin resin film. Examples of the polyester resin film include amorphous polyethylene terephthalate film and polyethylene naphthalate film. Examples of the polyolefin resin film include a polypropylene film, a polyethylene film, an ethylene-vinyl acetate copolymer film, and an ethylene-vinyl alcohol copolymer film. In addition, it is preferable that the glass transition temperature of the film for extending | stretching is 140 degrees C or less. The film thickness of the stretching film is not particularly limited, but is preferably about 20 to 800 μm, more preferably 100 to 400 μm.

  Application | coating of the hydrophilic polymer solution to the film for extending | stretching can be performed by the method generally known. For example, there are a roll coating method, a gravure coating method, a spray coating method, a dipping method, etc. Of course, the method is not limited to these. Although drying is normally performed at 100 degrees C or less, if it is the temperature which the film for extending | stretching does not deform | transform, it will not specifically limit. Prior to the application of the hydrophilic polymer solution to the stretching film, the surface of the stretching film may be subjected to a surface treatment. Examples of the surface treatment method include corona treatment, flame treatment, plasma treatment, and primer treatment. For the primer treatment, a conventionally known primer resin such as polyurethane resin or polyester resin can be used. The surface treatment may be performed to such an extent that the stretching film and the hydrophilic polymer layer do not peel off during the uniaxial stretching process or the dichroic substance adsorption process described later, and it is necessary to obtain a strong bond. There is no.

  The thickness of the hydrophilic polymer layer after drying is preferably about 2 to 50 μm, more preferably 3 to 20 μm.

<Process (2)>
In step (2), the “first laminate” obtained in step (1) described above is stretched. Thereby, an “stretched laminate” is obtained.

  The stretching process for the first laminate is usually a uniaxial stretching process. The uniaxial stretching process may be performed by a method of stretching uniaxially between rolls having different peripheral speeds, or by a method of stretching uniaxially by a tenter method. A method of stretching uniaxially is preferable. Moreover, although it may extend | stretch uniaxially using a hot roll and you may roll using a hot roll, the tenter method is used optimally. The draw ratio is usually about 4 to 8 times. Before and after the stretching treatment, steps such as preheating, heat treatment and cooling may be appropriately provided. The stretching temperature varies depending on the properties of the selected stretching film. For example, when the stretching film is an amorphous polyester resin film, stretching is performed at a temperature of about 70 to 120 ° C., preferably about 85 to 110 ° C. be able to. In the case of uniaxial stretching, good stretching can be achieved by adjusting the water content of the hydrophilic polymer layer on the stretching film to about 1 to 10% by mass, preferably about 2 to 8% by mass.

<Process (3)>
In step (3), the dichroic substance is adsorbed on the hydrophilic polymer layer obtained in step (1) described above. More preferably, boric acid treatment is also performed in combination with the adsorption treatment of the dichroic substance. Here, since the specific form of the dichroic material is as described above, detailed description thereof is omitted here.

  The adsorption treatment of the dichroic substance in the step (3) may be performed before the stretching of the first laminate in the step (2) or after the stretching, but is performed after the stretching. It is preferable.

  In addition, the dichroic substance adsorption treatment may be performed by, for example, using the “first laminate” obtained above (when the adsorption treatment is performed before stretching) or “stretching lamination” in an aqueous solution containing a dichroic substance. It can be performed by immersing the “body” (when the adsorption treatment is performed after stretching).

  When the dichroic substance is iodine, an aqueous solution containing iodine and potassium iodide is used as the dyeing bath. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by mass per 100 parts by mass of water, and the content of potassium iodide is usually about 0.5 to 10 parts by mass per 100 parts by mass of water. is there. The temperature of this aqueous solution is usually about 20 to 40 ° C., and the immersion time is usually about 30 to 300 seconds. In this operation, iodine is usually adsorbed only on the hydrophilic polymer layer in the first laminate or stretched laminate.

  When a dichroic organic dye is used as the dichroic substance, the content of the dichroic organic dye in the dyeing bath is usually about 0.001 to 0.1 parts by mass, preferably 0, per 100 parts by mass of water. 0.01 parts by mass or less. This dyeing bath may contain a plurality of dichroic organic dyes or may contain an inorganic salt such as sodium sulfate. When the dichroic organic dye is used, the adsorption treatment temperature is appropriately selected within a temperature range in which the hydrophilic polymer layer does not peel from the stretching film, and is, for example, about 20 to 80 ° C. The immersion time is usually about 30 to 300 seconds. Even in this operation, the dichroic organic dye is usually adsorbed only on the hydrophilic polymer layer in the first laminate or stretched laminate.

  The boric acid treatment is performed by immersing the first laminate or stretched laminate having a hydrophilic polymer layer on which a dichroic substance is adsorbed in an aqueous boric acid solution. The boric acid content in the boric acid aqueous solution is usually about 0.5 to 15 parts by mass, preferably about 1 to 12 parts by mass per 100 parts by mass of water. The boric acid treatment may be performed at a temperature at which the hydrophilic polymer layer does not peel from the stretching film. For example, it is appropriately selected from a temperature range of 30 ° C. or higher, preferably about 30 to 85 ° C. The boric acid treatment time is usually about 30 to 600 seconds, preferably about 60 to 300 seconds. When the dichroic dye is iodine, the boric acid aqueous solution may contain potassium iodide. When potassium iodide is contained, the content is usually about 0.5 to 20 parts by mass, preferably 1 to 15 parts by mass per 100 parts by mass of water.

  The laminate after the boric acid treatment is usually washed with water. This water washing treatment is performed, for example, by immersing the boric acid-treated laminate in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is usually about 2 to 120 seconds. Next, a drying treatment is performed. This drying is usually performed at a temperature of 100 ° C. or lower, preferably 40 to 95 ° C. The drying time is usually about 120 to 600 seconds.

  As described above, the “stretched laminate” in which the dichroic substance is adsorbed to the hydrophilic polymer layer is obtained through the steps (1) to (3). For example, as described in the examples described later, when a laminated film in which a polyvinyl alcohol-based resin having a thickness of 5 μm is coated on an amorphous polyethylene terephthalate film having a thickness of 250 μm is stretched 5 times on a horizontal axis as a starting film, The total thickness of the stretched laminate after the drying step is approximately 51 μm, for example. At this time, the film thickness of the hydrophilic polymer layer is about 1 μm. In the present invention, the thickness of the hydrophilic polymer layer (polarizer) is preferably 0.5 to 5.0 μm in order to reduce the thickness of the polarizing plate and reduce the shrinkage stress.

<Process (4)>
In the step (4), one of the polarizing plate protective films is applied to the “stretched laminate” obtained through the above-described steps (1) to (3) in which the dichroic substance is adsorbed to the hydrophilic polymer layer. The 2nd laminated body by which a hard-coat layer is arrange | positioned on the surface is bonded together. This bonding is performed so that the hydrophilic polymer layer of the stretched laminate and the polarizing plate protective film face each other. Thereby, the polarizing plate of the state by which the film for extending | stretching is arrange | positioned at one surface of a hydrophilic polymer layer (polarizer) is completed.

  A 2nd laminated body is a laminated body which has the structure by which a hard-coat layer is arrange | positioned at one surface of a polarizing plate protective film. The polarizing plate protective film constituting the second laminate corresponds to the “first polarizing plate protective film” described above, and various functional layers other than the hard coat layer are disposed on this. It may be. Further, the hard coat layer constituting the second laminate corresponds to the hard coat layer disposed on the surface of the above-mentioned “first polarizing plate protective film”. Therefore, detailed description of these specific forms is omitted here. In addition, there is no restriction | limiting in particular about the method of producing and forming a 1st polarizing plate protective film and a hard-coat layer, A conventionally well-known knowledge can be referred suitably. Here, an example of a method for producing the first polarizing plate protective film will be described below.

  The first polarizing plate protective film can be preferably used, whether it is a film manufactured by a solution casting method or a film manufactured by a melt casting method. However, it is preferably by the solution casting method. Therefore, below, it demonstrates taking the case of the manufacturing method of the 1st polarizing plate protective film (what has cellulose ester resin as a main component) by the solution casting method.

  The production of the first polarizing plate protective film by the solution casting method in the production method according to the embodiment includes, for example, a step of preparing a dope containing a cellulose ester resin and a solvent, and, if necessary, other additives; Cast on an endless metal support that moves indefinitely, drying the cast dope as a web, peeling from the metal support, stretching or maintaining the width, further drying, finished It is performed by a step of winding the film.

  First, the process for preparing the dope will be described. The concentration of cellulose ester resin in the dope is preferable because it can reduce the drying load after casting on the metal support, but if the concentration of cellulose ester resin is too high, the load during filtration increases and the filtration accuracy Becomes worse. The concentration for achieving both of these is preferably 10 to 35% by mass, and more preferably 15 to 25% by mass. As for various additives, it is preferable to batch-add a specified amount to the dope preparation kettle.

  The solvent used for the preparation of the dope may be used alone or in combination of two or more, but it is preferable in terms of production efficiency to use a mixture of a good solvent and a poor solvent of the cellulose ester resin, The more good solvent is preferable in terms of the solubility of the cellulose ester resin.

  The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose-ester resin to be used independently is defined as a good solvent, and what swells independently or does not melt | dissolve is defined as a poor solvent. Therefore, the good solvent and the poor solvent vary depending on the acyl group substitution degree of the cellulose ester resin.

  The good solvent is not particularly limited, and examples thereof include organic halogen compounds such as methylene chloride, dioxolanes, acetone, methyl acetate, and methyl acetoacetate. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although a poor solvent is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water is contained in dope.

  Moreover, the solvent used for melt | dissolution of cellulose-ester resin collect | recovers the solvent removed from the film by drying at the film-forming process, and this can be reused.

  There may be a trace amount of additives added to the cellulose ester resin in the recovered solvent, but even if they are contained, they can be reused preferably and can be purified and reused if necessary. It can also be used.

  As a method for dissolving the cellulose ester resin when preparing the dope described above, a general method can be used. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure.

  It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and does not boil under pressure, in order to prevent the formation of massive undissolved materials called gels and mamacos.

  In addition, a method in which a cellulose ester resin is mixed with a poor solvent and wetted or swollen, and then a good solvent is added and dissolved is also preferably used.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  A higher heating temperature with the addition of the solvent is preferable from the viewpoint of the solubility of the cellulose ester resin, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates.

  A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and further preferably 70 to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

  Alternatively, a cooling dissolution method is also preferably used, whereby the cellulose ester resin can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose ester resin solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small.

  For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable.

  It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose ester resin by filtration.

A bright spot foreign material is placed in a crossed Nicols state between two polarizing plates, a cellulose ester resin film or the like is placed between them, light is applied from one polarizing plate, and observation is performed from the other polarizing plate. The number of bright spots having a diameter of 0.01 mm or more is preferably 200 pieces / cm ² or less, more preferably 100 pieces / cm 2. ² or less, more preferably 50 pieces / m ² or less, and particularly preferably 0 to 10 pieces / cm ² . Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (referred to as differential pressure) is small and preferable.

  A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and even more preferably 45 to 55 ° C.

  A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

  Next, dope casting will be described.

  The metal support used in the casting process is preferably a mirror-finished surface, and a stainless steel belt or a drum whose surface is plated with a casting is preferably used as the metal support.

  The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. May deteriorate.

  A preferable support temperature is 0 to 55 ° C, and more preferably 25 to 50 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

  The manufacturing method of a 1st polarizing plate protective film includes the process of extending | stretching, after drying and peeling the film obtained by casting dope on a support body.

  In order for the 1st polarizing plate protective film to show favorable planarity, 10-150 mass% is preferable, and, as for the residual solvent amount at the time of peeling a web from a metal support body, More preferably, it is 20-40 mass% or 60. It is -130 mass%, Most preferably, it is 20-30 mass% or 70-120 mass%.

  In the present invention, the amount of residual solvent is defined by the following formula.

Where M is the mass of a sample taken during or after production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  Further, in the drying step of the first polarizing plate protective film, the web is preferably peeled off from the metal support and further dried to make the residual solvent amount 1% by mass or less, more preferably 0.1% by mass. Or less, particularly preferably 0 to 0.01% by mass or less.

  In the film drying process, generally, a roll drying method (a method in which a plurality of rolls arranged on the upper and lower sides are alternately passed through and dried) or a method of drying while transporting the web by a tenter method is adopted.

  The stretching operation for producing the first polarizing plate protective film can be sequentially or simultaneously stretched in the MD direction (casting direction or longitudinal direction) and TD direction (width direction) of the film. The draw ratio in the biaxial direction perpendicular to each other may be about 0 to 10% in the MD direction and about 5 to 40% in the TD direction.

  In particular, when a stretching treatment is performed at a relatively high temperature of 180 to 230 ° C., which is a relatively high temperature in the presence of a polyester compound (plasticizer), the polyester compound (plasticizer) coats around the matting agent (fine particles) and more aggregates. Is less likely to occur. At this time, the surface coating ability is higher when the molecular weight of the polyester compound (plasticizer) is smaller, and the coating ability is higher when the dicarboxylic acid group is a mixture of an aliphatic dicarboxylic acid and an aromatic dicarboxylic acid.

  Furthermore, it is preferable to maintain the amount of residual solvent at less than 5% by mass at the start of stretching because the in-plane retardations Ro and Rth can be easily adjusted to a preferable range and the effect on haze can be further improved. The measurement of the residual solvent is as described above, and the term “stretching start” as used herein refers to a point in time when stretching is actually started by gripping the end of the web with a clip if it is a tenter, for example. In order to keep the residual solvent amount at the start of stretching below 5% by mass, it is preferable to provide the drying step and evaporate the solvent in the process of peeling the web from the metal support and carrying it. If stretching is performed while retaining a residual solvent of 5% by mass or more, it is difficult to adjust the in-plane retardations Ro and Rth to a preferable range, and haze is likely to increase. A preferable residual solvent amount at the start of stretching is 4% by mass or less, more preferably 2% by mass or less, and particularly preferably 1% by mass or less. This operation is preferably performed online considering productivity.

  There is no particular limitation on the method of stretching the web. For example, a method in which peripheral speed differences are applied to a plurality of rolls and a roll peripheral speed difference is used to stretch in the MD direction, both ends of the web are fixed with clips and pins, and the distance between the clips and pins is increased in the traveling direction. And a method of stretching in the MD direction, a method of stretching in the transverse direction and stretching in the TD direction, a method of stretching in the MD / TD direction simultaneously and stretching in both the MD / TD directions, and the like. Of course, these methods may be used in combination. In the case of the so-called tenter method, driving the clip portion by the linear drive method is preferable because smooth stretching can be performed and the risk of breakage and the like can be reduced.

  These width maintenance or width direction stretching in the film forming process is preferably performed by a tenter, and may be a pin tenter or a clip tenter.

  The film transport tension in the film forming process such as in the tenter depends on the temperature, but is preferably 120 N / m to 200 N / m, and more preferably 140 N / m to 200 N / m. 140 N / m to 160 N / m is most preferable.

  The elastic modulus of the first polarizing plate protective film measured in a 23 ° C. and 55% RH environment is preferably 3.4 to 7.0 GPa in both the film longitudinal direction (MD) and the film width direction (TD). , TD elastic modulus / MD elastic modulus is preferably adjusted to be 1.05 to 2.0. In order to avoid the stability of stretching operation, breakage, and the like, the elastic modulus is preferably adjusted in the range of 3.4 to 4.5 GPa by the material type constituting the film and the ratio of the constituting material.

  The first polarizing plate protective film is preferably heat-set after stretching, but the heat-setting is higher than the final TD direction stretching temperature and is usually 0.5 to 300 seconds within a temperature range of Tg-20 ° C. or less. It is preferable to heat-set. Under the present circumstances, it is preferable to heat-fix, heating up sequentially in the range from which a temperature difference is set to 1-100 degreeC in the area | region divided into 2 or more.

  The heat-set film is usually cooled to Tg or less, and clip holding portions at both ends of the film are cut and wound. Under the present circumstances, it is preferable to carry out the relaxation | loosening process 0.1 to 10% in TD direction and / or MD direction within the temperature range below the last heat setting temperature and Tg. In addition, it is preferable that the cooling is gradually performed from the final heat setting temperature to Tg at a cooling rate of 100 ° C. or less per second. Means for cooling and relaxation treatment are not particularly limited, and can be performed by a conventionally known means. In particular, it is preferable to carry out these treatments while sequentially cooling in a plurality of temperature ranges from the viewpoint of improving the dimensional stability of the film. The cooling rate is a value obtained by (T1-Tg) / t, where T1 is the final heat setting temperature and t is the time until the film reaches Tg from the final heat setting temperature.

  The more optimal conditions of these heat setting conditions, cooling, and relaxation treatment conditions vary depending on the type of additives such as cellulose ester resin and plasticizer constituting the film, so the physical properties of the obtained stretched film are measured and preferable characteristics are obtained. What is necessary is just to determine by adjusting suitably so that it may have.

  The slow axis or the fast axis of the first polarizing plate protective film exists in the film plane, and θ1 is preferably −1 ° or more and + 1 ° or less when the angle formed with the film forming direction is θ1. More preferably, it is 0.5 ° or more and + 0.5 ° or less. This θ1 can be defined as an orientation angle, and the measurement of θ1 can be performed using an automatic birefringence meter KOBRA-21ADH or KOBRA-WR (Oji Scientific Instruments). Each of θ1 satisfying the above relationship can contribute to obtaining high luminance in a display image, suppressing or preventing light leakage, and contributing to obtaining faithful color reproduction in a color liquid crystal display device.

  As mentioned above, although the manufacturing method of the 1st polarizing plate protective film was demonstrated in detail, when the same film as a 1st polarizing plate protective film is used as a 2nd polarizing plate protective film, manufacture similar to the above is carried out. Of course, the method can be adopted. Moreover, also when the film which has a structure different from a 1st polarizing plate protective film is used as a 2nd polarizing plate protective film, such a 2nd polarizing plate is referred by referring conventionally known knowledge suitably. It is possible to prepare and produce a protective film.

  In order to bond the hydrophilic polymer layer (polarizer) and the polarizing plate protective film (first polarizing plate protective film) of the second laminate, for example, the first polarizing plate protective film is bonded. The side is preferably subjected to alkali saponification treatment and bonded to the exposed surface of the hydrophilic polymer layer (polarizer) using a completely saponified polyvinyl alcohol aqueous solution. About this pasting process, conventionally well-known knowledge can be referred to suitably.

  Here, when a transparent resin film is used as the stretching film, the stretched laminate after the adsorption treatment obtained above cannot be used as it is as a polarizing plate. However, the stretching film is damaged in the stretching process or the adsorption treatment process, or it is difficult to strengthen the adhesion between the stretching film and the hydrophilic polymer layer, or the stretching film is crystallized in the stretching process. In general, it is difficult to directly use the stretching film as a polarizing plate protective film because the transparency may be lowered due to the progress of the film. On the other hand, a polarizing plate without the above problems can be obtained by adopting a method of bonding a polarizing plate protective film and a hydrophilic polymer layer (polarizer) as in the production method according to the present invention. Can be manufactured.

  Moreover, according to the manufacturing method which concerns on this form, the 2nd laminated body bonded with an extending | stretching laminated body is a structure by which a hard-coat layer is arrange | positioned on the surface of a polarizing plate protective film (1st polarizing plate protective film). It has been found that manufacturing advantages can also be obtained. That is, when a solution of a hydrophilic polymer such as polyvinyl alcohol resin is applied to the surface of the stretching film and dried, curling occurs with the stretching film side inward, and this curling remains after the stretching process. I found out that This is in contrast to the phenomenon in which curling occurs with the coating side facing inward when a photocurable resin solution is applied to the surface of the resin film and cured.

  On the other hand, also in the second laminate, a hard coat layer is disposed on the surface of a polarizing plate protective film (first polarizing plate protective film) having a predetermined bending rigidity value so that the hard coat layer side is on the inside. Moderate curl. As a result, even when the hydrophilic polymer layer of the stretched laminate and the polarizing plate protective film in which the curling occurred with the stretching film side facing inward are bonded together, it is not necessary to apply force to force uniform bonding. Can be achieved. Thereby, the production yield of the polarizing plate can be improved. In addition, since the residual stress on the hydrophilic polymer layer (polarizer) is reduced, it is possible to improve the durability of the polarizing plate (particularly, the durability under high humidity conditions). Conventionally, in order to prevent the occurrence of curling of the polarizing plate protective film accompanying the shrinkage of the hard coat layer, the composition and film thickness of the polarizing plate protective film and the hard coat layer are set so as to prevent such curling from occurring as much as possible. It was common to design. On the other hand, according to the manufacturing method according to the present embodiment, the production yield and the durability of the polarizing plate are remarkably improved by intentionally generating an appropriate curl as described above.

<Other processes>
After the polarizing plate is manufactured as described above, the following steps can be further performed.

  For example, it is good also as a finished product of a polarizing plate by performing the process of peeling and removing the film for extending | stretching. In this case, when the film for stretching is peeled / removed, the film is charged, and dust may be attracted to induce a defect in a later process, thereby reducing the yield in the manufacturing process. Therefore, it is preferable to subject the film to be used to antistatic treatment. The antistatic treatment is applied to all of the stretching film, the primer layer of the stretching film, the hydrophilic polymer layer (polarizer), the polarizing plate protective film, and the adhesive between the polarizing plate protective film and the hydrophilic polymer layer. Although it is preferable to apply it to any of them, a corresponding effect is exhibited even if it is applied to any of them. In particular, it is effective to apply an antistatic treatment to the stretching film. As a method of directly applying an antistatic treatment to the film, for example, a surfactant, a cationic antistatic agent such as ammonium, an organic antistatic agent such as an anionic antistatic agent, or tin oxide, indium oxide, There is a method in which an inorganic antistatic agent in which an inorganic compound having conductivity such as antimony oxide is dispersed in a suitable binder such as pentaerythritol is applied to the surface of the stretching film. Further, the antistatic agent as described above may be mixed in advance in the film or adhesive.

  Moreover, you may paste another polarizing plate protective film on the surface of the hydrophilic polymer layer (polarizer) which exposed the film for extending | stretching by peeling and removal. Thereby, the polarizing plate of the form with which both surfaces of the hydrophilic polymer layer (polarizer) were sandwiched by the polarizing plate protective film is obtained. In addition, another polarizing plate protective film used in this case corresponds to the above-mentioned “second polarizing plate protective film”. Therefore, detailed description of the specific form is omitted here.

≪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 manufactured. In addition, since the production yield of the polarizing plate according to the present invention is greatly improved, 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, and 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 the present invention may of course be carried out by referring to other conventionally known technical matters (for example, JP 2010-3060 A). .

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

≪Resin used for production of polarizing plate protective film≫
The following three types of resin components used for preparing the polarizing plate protective film were prepared:
Resin A: Zeonore (cyclic olefin resin film, manufactured by Nippon Zeon Co., Ltd., trade name “1020R”)
Resin B: Arton (Cyclic olefin resin film, manufactured by JSR Corporation, trade name “F5023”)
Resin C: Acrypet (acrylic resin film, manufactured by Mitsubishi Rayon Co., Ltd., trade name “VH5”)
In addition, when using it for preparation of the following dope solutions, it cut | judged to the appropriate size so that these resin may melt | dissolve in a solvent easily.

«Polarizing plate protective film No. Production of 101-112 >>
(Preparation of dope solution 101)
Resin A 100 parts by weight Methylene chloride 480 parts by weight The above was put into a sealed container, heated and stirred, and completely dissolved. Azumi Filter Paper No. Azumi Filter Paper No. No. 24 was used for filtration to prepare a dope solution 101. In the film production line, the dope solution 101 was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd.

(Silicon dioxide dispersion dilution 1)
Aerosil 200V (Nippon Aerosil Co., Ltd., average particle size 12 nm, apparent specific gravity 100 g / liter) 2 parts by mass Ethanol 18 parts by mass The above was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. The liquid turbidity after dispersion was 100 ppm. 18 parts by mass of methylene chloride was added to this dispersion while stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a silicon dioxide dispersion dilution 1.

(Preparation of inline additive solution 1)
Tinuvin 109 (manufactured by BASF Japan Ltd.) 11 parts by mass Tinuvin 171 (manufactured by BASF Japan Ltd.) 5 parts by mass Methylene chloride 100 parts by mass Dope solution 101 6 parts by mass The above was put into a sealed container, heated and stirred. While completely dissolved and filtered.

  To this, 20 parts by mass of silicon dioxide dispersion diluted solution 1 was added with stirring, and the mixture was further stirred for 60 minutes, followed by filtration with Advantech Toyo Corp. polypropylene wind cartridge filter TCW-PPS-1N to prepare inline additive solution 1 did. In the inline additive solution 1 line, the inline additive solution 1 was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. 2.5 parts by mass of the filtered inline additive 1 is added to 100 parts by mass of the filtered dope solution 101, and the mixture is sufficiently mixed with an inline mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ). Using a rolling apparatus, the film was uniformly cast on a stainless steel band support at a temperature of 35 ° C. and a width of 1800 mm.

  With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100%, and the stainless steel band support was peeled off. The peeled web was evaporated at 35 ° C., slit to 1650 mm width, and then stretched 1.1 times in the TD direction (direction orthogonal to the film transport direction) with a tenter at a drying temperature of 130 ° C. , Dried. Thereafter, drying is completed while transporting the drying zone at 120 ° C. and 110 ° C. with a number of rolls, slitting to a width of 1400 mm, a knurling process with a width of 15 mm and an average height of 10 μm is applied to both ends of the film, and an initial winding tension of 220 N / M, with a final tension of 110 N / m, wound around a 6 inch inner core, and polarizing plate protective film no. 101 was obtained. The obtained polarizing plate protective film No. The residual solvent amount of 101 was 0.2%, the average film thickness was 40 μm, and the number of turns was 1000 m.

  As shown in Table 1 below, the type of the resin is changed, and the casting amount is adjusted. 102-112 were produced, respectively.

≪Preparation of polarizing plate protective film 113≫
(Silicon dioxide dispersion dilution 2)
Aerosil 972V (manufactured by Nippon Aerosil Co., Ltd., average particle size of 16 nm, apparent specific gravity 90 g / liter) 12 parts by mass Ethanol 88 parts by mass The above was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 88 parts by mass of methylene chloride was added to this dispersion while stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a silicon dioxide dispersion dilution 2.

(Preparation of inline additive solution 2)
Tinuvin 109 (manufactured by BASF Japan Ltd.) 11 parts by mass Tinuvin 171 (manufactured by BASF Japan Ltd.) 5 parts by mass Methylene chloride 100 parts by mass The above was put into a sealed container and heated, stirred and completely dissolved. And filtered.

  To this, 36 parts by mass of silicon dioxide dispersion diluent 2 was added with stirring, and the mixture was further stirred for 30 minutes, and then cellulose acetate propionate (acetyl group substitution degree 1.9, propionyl group substitution degree 0.8) 6 masses. The components were added with stirring, and further stirred for 60 minutes, and then filtered through a polypropylene wind cartridge filter TCW-PPS-1N manufactured by Advantech Toyo Co., Ltd. to prepare an in-line additive solution 2.

(Preparation of dope solution 113)
Cellulose ester (TAC1; cellulose triacetate synthesized from linter cotton, Mn = 148000, Mw = 310000, Mw / Mn = 2.1, acetyl group substitution degree 2.92) 100 parts by mass Trimethylolpropane tribenzoate (PX861) 5 0.0 parts by mass Ethylphthalyl ethyl glycolate (EPEG) 5.5 parts by mass Methylene chloride 440 parts by mass Ethanol 40 parts by mass The above is put into a closed container, heated and stirred, and completely dissolved. Azumi filter paper No. 24, and the dope liquid 113 was prepared.

  In the film production line, the dope solution 113 was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. In the inline additive solution 2 line, the inline additive solution 2 was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd.

  3 parts by mass of the filtered inline additive solution 2 is added to 100 parts by mass of the filtered dope solution 113 and sufficiently mixed with an inline mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ), and then a belt casting apparatus. Was cast uniformly on a stainless steel band support at a temperature of 32 ° C. and a width of 1800 mm. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100%, and the stainless steel band support was peeled off. The peeled cellulose ester web was evaporated at 35 ° C., slit to 1650 mm width, and then stretched by 1.05 times in the TD direction (direction perpendicular to the film transport direction) with a tenter. Dried at the drying temperature. At this time, the amount of residual solvent when starting stretching with a tenter was 20%.

  Thereafter, drying is completed while transporting the drying zone at 120 ° C. and 110 ° C. with a number of rolls, slitting to a width of 1400 mm, a knurling process with a width of 15 mm and an average height of 10 μm is applied to both ends of the film, and an initial winding tension of 220 N / M, with a final tension of 110 N / m, wound around a 6 inch inner core, and polarizing plate protective film no. 113 was obtained. The draw ratio in the MD direction (same direction as the film transport direction) immediately after peeling calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.07. Polarizing plate protective film No. The residual solvent amount of 113 was 0.2%, the average film thickness was 25 μm, and the number of turns was 1000 m.

«Polarizing plate protective film No. Production of 114, 116, 117, 120 >>
(Silicon dioxide dispersion dilution 3)
Aerosil R812 (manufactured by Nippon Aerosil Co., Ltd., average diameter of primary particles: 7 nm) 10 parts by mass Ethanol 90 parts by mass The above was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 88 parts by mass of methylene chloride was added to 100 parts by mass of this dispersion while stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a silicon dioxide dispersion diluted liquid 3. The fine particle dispersion diluted solution was filtered with a filter (Advantech Toyo Co., Ltd .: polypropylene wind cartridge filter TCW-PPS-1N).

(Synthesis of ester compound 1)
In a nitrogen atmosphere, dimethyl terephthalate (4.85 g), 1,2-propylene glycol (4.4 g), and tetraisopropyl titanate (10 mg) were mixed and stirred at 140 ° C. for 2 hours, and then p-toluic acid (6.8 g) was added. Stir for another 2 hours. Thereafter, the mixture was stirred at 210 ° C. for 16 hours. Next, the temperature was lowered to 170 ° C., and unreacted 1,2-propylene glycol was distilled off under reduced pressure to obtain an ester compound 1 having a structure represented by the following chemical formula. In the obtained ester compound 1, n was 1.

(Preparation of dope solution 114)
Cellulose ester (TAC2; cellulose triacetate synthesized from linter cotton, acetyl group substitution degree 2.88, Mn = 14000) 90 parts by mass Ester compound 1 (n = 1) 10 parts by mass Tinuvin 928 (manufactured by BASF Japan Ltd.) 2.5 parts by mass Silicon dioxide dispersion diluted solution 3 4 parts by mass Methylene chloride 432 parts by mass Ethanol 38 parts by mass The above was put into a sealed container, heated and stirred to dissolve completely, and manufactured by Azumi Filter Paper Co., Ltd. Azumi Filter Paper No. 24, and the dope liquid 114 was prepared.

  Next, using a belt casting apparatus, it was cast uniformly on a stainless steel band support at a temperature of 35 ° C. and a width of 1800 mm. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100%, and the stainless steel band support was peeled off. The peeled cellulose ester web was evaporated at 35 ° C., slit to 1700 mm width, and then stretched 1.3 times in the TD direction (direction perpendicular to the film transport direction) with a tenter, Dried at the drying temperature. At this time, the amount of residual solvent when starting stretching with a tenter was 20%.

  Thereafter, drying is completed while transporting the drying zone at 120 ° C. with many rolls, slitting to a width of 2200 mm, a knurling process with a width of 15 mm and an average height of 10 μm is applied to both ends of the film, and an initial winding tension of 220 N / m, The film was wound around a 6-inch inner diameter core with a final tension of 110 N / m. 114 was obtained. The draw ratio in the MD direction (same direction as the film transport direction) immediately after peeling calculated from the rotational speed of the stainless steel band support and the operating speed of the tenter was 1.01. Polarizing plate protective film No. The residual solvent amount of 114 was 0.2%, the average film thickness was 25 μm, and the number of turns was 1000 m.

  Except for adjusting the casting amount so that the average film thickness after drying becomes the value shown in Table 2 below, polarizing plate protective film No. In the same manner as in FIG. 116, 117, and 120 were made.

<< Production of Polarizing Plate Protective Films 115, 118, 119, 121 >>
(Preparation of dope solution 115)
Cut cellulose ester film (TAC3; cellulose triacetate film manufactured by FUJIFILM Corporation (trade name “Fujitac TD40UL”)) 90 parts by mass Methylene chloride 432 parts by mass Ethanol 35 parts by mass While being completely dissolved, Azumi Filter Paper No. 24, and the dope liquid 115 was prepared.

  Except for adjusting the casting amount so that the average film thickness after drying becomes the value shown in Table 2 below, polarizing plate protective film No. In the same manner as in 115, polarizing plate protective film No. 118, 119, and 121 were made.

≪Preparation of hard coat layer≫
On the above polarizing plate protective film, clear hard coat processing was performed according to the following procedure to prepare a clear hard coat layer.

On the above polarizing plate protective film, the following hard coat layer forming composition is filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a hard coat layer forming coating solution, and this is applied using a micro gravure coater. After applying and drying at 70 ° C., while purging with nitrogen so that the atmosphere has an oxygen concentration of 1.0% by volume or less, the illuminance of the irradiated part is 100 mW / cm ² and the irradiation amount is 0.1 J / kg using an ultraviolet lamp. The coating layer was cured as cm ² to form a clear hard coat layer having a dry film thickness of 3.0 μm and wound up.

<Composition for forming hard coat layer>
(Preparation of fluorine-siloxane graft polymer)
Hereinafter, commercially available product names of materials used for preparing the fluorine-siloxane graft polymer are shown.

Radical polymerizable fluororesin (A): Cefal coat CF-803 (hydroxyl value 60, number average molecular weight 15,000; manufactured by Central Glass Co., Ltd.)
One-end radical polymerizable polysiloxane (B): Silaplane FM-0721 (number average molecular weight 5,000; manufactured by Chisso Corporation)
Radical polymerization initiator: Perbutyl O (t-butylperoxy-2-ethylhexanoate; manufactured by NOF Corporation)
Curing agent: Sumidur N3200 (biuret-type prepolymer of hexamethylene diisocyanate; manufactured by Sumitomo Bayer Urethane Co., Ltd.)
[Synthesis of radical polymerizable fluororesin (A)]
A glass reactor equipped with a mechanical stirrer, a thermometer, a condenser and a dry nitrogen gas inlet was added to cefral coat CF-803 (1554 parts by mass), xylene (233 parts by mass), and 2-isocyanatoethyl methacrylate (6 3 parts by mass) and heated to 80 ° C. in a dry nitrogen atmosphere. After reacting at 80 ° C. for 2 hours and confirming that the absorption of isocyanate disappeared by the infrared absorption spectrum of the sample, the reaction mixture was taken out and 50% by mass of radically polymerizable fluororesin (A) via a urethane bond. Got.

  Next, the radically polymerizable fluororesin (A) (26.1 parts by mass) synthesized above and xylene (19.19 parts) were added to a glass reactor equipped with a mechanical stirrer, a thermometer, a condenser and a dry nitrogen gas inlet. 5 parts by mass), n-butyl acetate (16.3 parts by mass), methyl methacrylate (2.4 parts by mass), n-butyl methacrylate (1.8 parts by mass), lauryl methacrylate (1.8 parts by mass), 2 -Hydroxyethyl methacrylate (1.8 parts by mass), FM-0721 (5.2 parts by mass), and perbutyl O (0.1 parts by mass) were added and heated to 90 ° C in a nitrogen atmosphere. Hold for 2 hours. Perbutyl O (0.1 part) was added and the mixture was further held at 90 ° C. for 5 hours to obtain a fluorine-siloxane graft polymer solution having a weight average molecular weight of 171,000 and a concentration of 35% by mass.

  The weight average molecular weight was determined by GPC. The mass% of the fluorine-siloxane graft polymer was determined by HPLC (liquid chromatography).

  The following materials were stirred and mixed to form a hard coat layer forming composition.

(Polyfunctional acrylate)
Pentaerythritol triacrylate 20 parts by mass Pentaerythritol tetraacrylate 50 parts by mass Dipentaerythritol hexaacrylate 30 parts by mass Dipentaerythritol pentaacrylate 30 parts by mass (photopolymerization initiator)
Irgacure 184 (manufactured by BASF Japan) 5 parts by mass Irgacure 907 (manufactured by BASF Japan) 10 parts by mass (additive)
Fluorine-siloxane graft polymer (35% by mass) 5 parts by mass Pentaerythritol tetrakis (3-mercaptobutyrate) 2.5 parts by mass (solvent)
Propylene glycol monomethyl ether 10 parts by weight Methyl acetate 20 parts by weight Acetone 20 parts by weight Methyl ethyl ketone 60 parts by weight Cyclohexanone 20 parts by weight << Evaluation of properties of polarizing plate protective film >>
About the 1st polarizing plate protective film produced above, the following physical properties and performance were evaluated.

(Measurement of elastic modulus)
Each polarizing plate protective film before applying the clear hard coat layer is cut into 2 cm × 7 cm (the long axis is the MD direction of the film), and Tensilon (manufactured by A & D Co., Ltd.) at 25 ° C. and 55% RH. ) Was used to perform a tensile test, and the tensile elastic modulus (E _M ) was measured. The direction of cutting was changed by 90 °, and the tensile elastic modulus (E _T ) was measured in the same manner.

(Film and clear hard coat layer thickness)
The thickness of the film and the thickness of the clear hard coat layer were measured using a film thickness meter (Code No. 547-401, manufactured by Mitutoyo Corporation).

(Calculation of bending stiffness)
Using the average value of elastic modulus (E _M , E _T ) measured above and the value of film thickness, based on the above formula (3), the Poisson's ratio of the film is 0.4, and the bending rigidity of the polarizing plate protective film The value of was calculated. The results are shown in Table 3 below.

≪Production of stretched laminate≫
An amorphous polyethylene terephthalate sheet having a thickness of 250 μm subjected to antistatic treatment was prepared as a stretching film, and the surface thereof was corona treated. On this corona-treated surface, a 5% by weight aqueous solution of a polyvinyl alcohol resin having a polymerization degree of 2400 and a saponification degree of 99.9% or more, which is a hydrophilic polymer, was coated with a bar coater and then heated in a hot air drying oven at 50 ° C. It was dried for 5 minutes to form a 5 μm thick polyvinyl alcohol layer (hydrophilic polymer layer) to obtain a first laminate. The obtained 1st laminated body was extended | stretched 5 times to the horizontal uniaxial at 100 degreeC using the tenter drawing machine, and the extending | stretching laminated body was obtained. After this stretched laminate was immersed in pure water at 25 ° C. for 1 minute, it was immersed in an aqueous solution containing 0.25 parts by mass of iodine and 5 parts by mass of potassium iodide per 100 parts by mass of water at a temperature of 28 ° C. for 180 seconds. did. Subsequently, it was immersed in a boric acid aqueous solution containing 7.5 parts by mass of boric acid and 6 parts by mass of potassium iodide per 100 parts by mass of water at a temperature of 40 ° C. for 300 seconds. Thereafter, it was washed with pure water at 15 ° C. for 2 seconds. The film washed with water was dried at 50 ° C. for 300 seconds to obtain a stretched laminate in which iodine as a dichroic material was adsorbed on the hydrophilic polymer layer. At this time, the film thickness of the hydrophilic polymer layer excluding the stretching film was 1 μm.

≪Preparation of polarizing plate≫
(Preparation of polarizing plates No. 101 to 112)
Polarizing plate protective film No. 1 prepared above with a clear hard coat layer disposed thereon. 101, the surface opposite to the clear hard coat layer was subjected to corona discharge treatment so that the wetting index was 56 mN / m, and the surface of the stretched laminate produced above was coated with a polarizing plate. Protective film No. The corona-treated surface of 101 was bonded via an adhesive composed of a 5% by weight polyvinyl alcohol aqueous solution and dried at 50 ° C. for 5 minutes. After drying, the stretching film was peeled off and removed, and polarizing plate protective film No. Polarizing plate No. 101 with 101 is attached. 101 was obtained.

  Polarizing plate protective film No. 101 is polarizing plate protective film No. 101. Except for changing to 102-112, polarizing plate No. In the same manner as in 101, polarizing plate No. 102-112 were produced.

(Preparation of polarizing plates No. 113 to 121)
Polarizing plate protective film No. 1 prepared above with a clear hard coat layer disposed thereon. The surface opposite to the clear hard coat layer is subjected to saponification treatment for 60 seconds using a 50 ° C. 2N KOH aqueous solution on the surface opposite to the clear hard coat layer, washed with water, and dried. Protective film No. In the same manner as in 101, the stretched laminate produced above was bonded and dried on the hydrophilic polymer layer side surface. After drying, the stretching film was peeled off and removed, and polarizing plate protective film No. Polarizing plate No. 113 with 113 is attached. 113 was obtained.

  Polarizing plate protective film No. 113 is polarizing plate protective film No. Except for changing to 114-121, polarizing plate No. In the same manner as in 113, polarizing plate No. 114-121 were produced.

(Preparation of polarizing plates No. 122 to 125)
Polarizing plate No. produced above. 119, on the exposed surface of the hydrophilic polymer layer, a 40 μm thick triacetyl cellulose film (manufactured by Konica Minolta Advanced Layer Co., Ltd., trade name: KC4UE, Ro = 0.7 nm, Rth = −0.1 nm) A saponified surface was pasted as a second polarizing plate protective film. 122 was produced.

  The polarizing plate No. was changed except that the second polarizing plate protective film was changed to the following configuration. In the same manner as in FIG. 123-125 were produced.

<Second polarizing plate protective film>
Polarizing plate No. 123: A film obtained by subjecting a surface of a triacetylcellulose film (trade name: Z-TAC, Ro = 1 nm, Rth = 0 nm) having a thickness of 80 μm to a saponification plate. 124: The surface of a norbornene polymer film “ZEONOR ZF14-040” (manufactured by Optes Co., Ltd.) subjected to corona discharge treatment using a solid state corona treatment machine 6KVA (manufactured by Pillar Co., Ltd.). 125: The surface of an acrylic film having a thickness of 60 μm produced by the method described in Example 1 of JP-A-2009-294261 was subjected to corona discharge treatment in the same manner as above (production of polarizing plate No. 126)
A roll-shaped polyvinyl alcohol film having a thickness of 80 μm continuously dyed in an aqueous iodine solution was stretched 5 times in the transport direction and dried to obtain a long polarizer. A retardation film F1 produced as described in Example 1 of JP-A-2009-265295 is formed on one surface of this polarizer, and the surface on which the first optically anisotropic layer is not formed is polyvinyl alcohol-based. It bonded through the adhesive agent. At this time, the absorption axis of the polarizer is parallel to the longitudinal direction, and the angle formed by the absorption axis of the polarizer and the slow axis of the second optical anisotropic layer (cellulose ester film) is 90 °. Met. On the other side, the surface of a 40 μm thick triacetyl cellulose film (manufactured by Konica Minolta Advanced Layer Co., Ltd., trade name: KC4UE, Ro = 0.7 nm, Rth = −0.1 nm) is saponified. Are bonded together continuously using a polyvinyl alcohol-based adhesive. 126 was produced.

≪Evaluation of properties of polarizing plate≫
(Evaluation of productivity of polarizing plate)
Polarizing plate No. produced above. About 101-125, productivity at the time of manufacture was evaluated. Specifically, based on the number of bubble entrainment and convex faults that occur when the polarizing plate protective film is bonded within the roll length of 2 m when produced as described above, evaluation is performed using the following indicators. did. The results are shown in Table 4 below.
◎: No failure part ○: There is one failure part △: There are 2-3 failure parts ×: There are four or more failure parts This index is at a level where there is no practical problem if it is more than ○ .

  In addition, the failure part measured by visually observing by the presence or absence of the bright spot at the time of arrange | positioning the polarizing plate produced on the Schaukasten (surface light source device), and arrange | positioning another polarizing plate in a crossed Nicol state.

≪Production of liquid crystal display device≫
(Production of liquid crystal display devices No. 101 to 125)
The polarizing plate on the viewing side of the 42-inch liquid crystal color television (Regza 42R1, manufactured by Toshiba Corporation) is peeled off, the absorption axis is directed in the same direction as the peeled polarizing plate, and the polarizing plate protective film prepared above is the outermost surface. (The clear hard coat layer is on the outermost layer) and the polarizing plate No. 1 prepared above was used. 101-125 are bonded through an adhesive layer, and the liquid crystal display device No. 101-125 were produced.

(Production of liquid crystal display device No. 126)
Liquid crystal display device no. In the production of 122, the polarizing plate on the backlight side of the color television is further peeled off, and the polarizing plate No. 1 produced above is oriented so that the absorption axis is directed in the same direction as the peeled backlight side polarizing plate. 126 is bonded through an adhesive layer, and the liquid crystal display device No. 126 was produced.

≪Evaluation of physical properties of liquid crystal display device≫
(Durability test evaluation)
The liquid crystal display device produced above is displayed in black, left in an environment of 23 ° C. and 23% RH for 24 hours, then left in an environment of 23 ° C. and 80% RH for 24 hours, and displayed in black in a dark room. The display unevenness was visually observed and evaluated using the following indicators. The results are shown in Table 4 below.
◎: Unevenness is not seen at all ○: Light leakage is slightly seen at the four corners △: Unevenness is slightly seen overall ×: Unevenness is seen overall, this index is practical if it is more than Δ There is no problem level.

  From the results shown in Table 4, according to the polarizing plate of the present invention including the polarizing plate protective film (first polarizing plate protective film) whose bending rigidity is a value within a predetermined range, even when the thickness is reduced. Thus, it is understood that a polarizing plate excellent in durability is provided in which a decrease in production yield is prevented and display unevenness when a liquid crystal display device is formed is reduced.

  This application is based on Japanese Patent Application No. 2012-48428 filed on March 5, 2012, the disclosure of which is referred to and incorporated in its entirety.

10 Backup roll,
20 Laminate roll,
30 polarizing plate,
32. A substrate having a coating type polarizer,
34 A first polarizing plate protective film having a hard coat layer.

1. Applying a solution containing a hydrophilic polymer to the surface of the stretching film and drying to form a hydrophilic polymer layer to obtain a first laminate;
Stretching the first laminate to obtain a stretched laminate;
Adsorbing a dichroic substance on the hydrophilic polymer layer;
The second laminate in which a hard coat layer is disposed on one surface of the first polarizing plate protective film, the stretched laminate so that the first polarizing plate protective film and the hydrophilic polymer layer face each other. A process of bonding to the body,
including,
A polarizer,
A first polarizing plate protective film disposed on one surface of the polarizer;
A hard coat layer disposed on a surface opposite to the polarizer of the first polarizing plate protective film ,
The film thickness of the polarizer is 0.5 to 5.0 μm,
The bending stiffness in 25 ° C. 55% RH of the first polarizing plate protective film is 0.0002~0.025mPa · ^{m 3,} the production method of the polarizing plate;
2. The manufacturing method according to 1 above, wherein the film thickness of the first polarizing plate protective film is 15 to 35 μm;
3. The manufacturing method according to 1 or 2 above, wherein the first polarizing plate protective film contains a cellulose ester resin;
4). The manufacturing method of any one of said 1-3 whose said polarizer contains polyvinyl alcohol;
5. The manufacturing method according to any one of the above 1 to 4, wherein a second polarizing plate protective film is disposed on the surface of the polarizer opposite to the first polarizing plate protective film;
6 . The manufacturing method of any one of said 1-5 which further includes the process of peeling and removing the said film for extending | stretching;
7 . After the step of peeling / removing the stretching film, the method further includes a step of bonding a second polarizing plate protective film to the surface of the hydrophilic polymer layer opposite to the first polarizing plate protective film. And the production method according to 6 above;
8 . A display device comprising a polarizing plate produced by the production method according to any one of 1 to 7 above.

Claims (9)

A polarizer,
A first polarizing plate protective film disposed on one surface of the polarizer;
A hard coat layer disposed on a surface opposite to the polarizer of the first polarizing plate protective film;
A polarizing plate comprising
The polarizer has a thickness of 0.5 to 5.0 μm,
Said first flexural rigidity at 25 ° C. 55% RH of the polarizing plate protective film is 0.0002~0.025mPa · ^{m 3,} a polarizing plate.   The polarizing plate of Claim 1 whose film thickness of a said 1st polarizing plate protective film is 15-35 micrometers.   The polarizing plate according to claim 1, wherein the first polarizing plate protective film contains a cellulose ester resin.   The polarizing plate according to claim 1, wherein the polarizer contains polyvinyl alcohol.   The polarizing plate according to any one of claims 1 to 4, wherein a second polarizing plate protective film is disposed on a surface of the polarizer opposite to the first polarizing plate protective film. Applying a solution containing a hydrophilic polymer to the surface of the stretching film and drying to form a hydrophilic polymer layer to obtain a first laminate;
Stretching the first laminate to obtain a stretched laminate;
Adsorbing a dichroic substance on the hydrophilic polymer layer;
A second laminate in which a hard coat layer is disposed on one surface of a first polarizing plate protective film having a flexural rigidity at 25 ° C. and 55% RH of 0.0002 to 0.025 mPa · m ³ , A step of bonding to the stretched laminate so that the polarizing plate protective film of 1 and the hydrophilic polymer layer face each other;
The manufacturing method of a polarizing plate containing.   The manufacturing method of Claim 6 which further includes the process of peeling and removing the said film for extending | stretching.   After the step of peeling / removing the stretching film, the method further includes a step of bonding a second polarizing plate protective film to the surface of the hydrophilic polymer layer opposite to the first polarizing plate protective film. The manufacturing method according to claim 7.   The display apparatus provided with the polarizing plate manufactured by the polarizing plate of any one of Claims 1-5, or the manufacturing method of any one of Claims 6-8.