JP2009139525A - Polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a polarizing plate provided with a transparent protective film having excellent isotropy and preventing the occurrence of knicks. <P>SOLUTION: This polarizing plate 1 is constituted by laminating the transparent protective film 2, the polarizer 3, and a birefringent layer 4 sequentially in this order. The transparent protective film 2 includes (meth)acrylic resin having a glutaric anhydride structure. The transparent protective film 2 and the polarizer 3 are mutually bonded by using polyvinyl alcohol adhesive 5 containing metallic compound colloid. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a polarizing plate and a liquid crystal display device.

  In a liquid crystal display device, it is indispensable to dispose polarizers on both sides of a glass substrate that forms the surface of the liquid crystal cell. A polarizer is generally obtained by dyeing a polyvinyl alcohol film with a dichroic substance such as iodine, cross-linking with a cross-linking agent, and uniaxially stretching. Since this polarizer is stretched, it easily contracts. Moreover, since polyvinyl alcohol is a hydrophilic polymer, the polyvinyl alcohol film is very easily deformed particularly under humidified conditions. Moreover, since the mechanical strength of the film itself is weak, there is a problem that the film is torn. For this reason, the polarizing plate which supplemented the intensity | strength is used by bonding the transparent protective film which consists of a triacetyl cellulose film on both surfaces or one side of a polarizer. This polarizing plate is manufactured by bonding a polarizer and a transparent protective film through an adhesive.

  As the transparent protective film, a triacetyl cellulose film is used as described above. However, the triacetyl cellulose film has a retardation in the thickness direction (that is, an anisotropic film). If a transparent protective film having a phase difference is used for the polarizing plate, it may adversely affect the viewing angle characteristics of the liquid crystal display device. For this reason, the polarizing plate using the transparent protective film which does not have a phase difference substantially is calculated | required.

  Moreover, as a polarizing plate adhesive used for adhesion | attachment with a polarizer and a transparent protective film, a water-soluble adhesive is preferable. For example, a polyvinyl alcohol adhesive in which a crosslinking agent is mixed with an aqueous polyvinyl alcohol solution is used. However, when a polarizer and a transparent protective film are bonded together using a polyvinyl alcohol-based adhesive, peeling may occur at the interface between the polarizer and the transparent protective film under humidified conditions. For this problem, for example, an adhesive for polarizing plates containing a polyvinyl alcohol-based resin containing an acetoacetyl group and a crosslinking agent has been proposed (see Patent Document 1).

On the other hand, when producing a polarizing plate, if a polarizer and a transparent protective film are bonded together via the said polyvinyl alcohol-type adhesive agent, there exists a problem that a nick will generate | occur | produce. This nick (also called volatile point) is a local irregularity defect that occurs at the interface between the polarizer and the transparent protective film. For the occurrence of this nick, for example, a polarizer obtained by treating the surface of a polyvinyl alcohol film with adjusted water content with a calender roll under a predetermined condition is laminated with a transparent protective film to obtain a polarizing plate. A method has been proposed (see Patent Document 2). However, in the technique described in Patent Document 2, it cannot be said that generation of nicks can be sufficiently suppressed, and a polarizing plate in which generation of nicks is further suppressed is required.
JP-A-7-198945 Japanese Patent Laid-Open No. 10-166519

  An object of the present invention is to provide a polarizing plate in which the transparent protective film is excellent in isotropy, and further the generation of nicks is suppressed, and a liquid crystal display device including the polarizing plate.

  The polarizing plate of the present invention is a polarizing plate in which a transparent protective film, a polarizer, and a birefringent layer are laminated in this order. The transparent protective film has a (meth) acrylic acid anhydride structure. The transparent protective film and the polarizer are bonded together using a polyvinyl alcohol-based adhesive containing a metal compound colloid.

The transparent protective film containing the (meth) acrylic resin having the glutaric anhydride structure is excellent in isotropy. For example, the in-plane retardation value (Re (590)) of the transparent protective film at a wavelength of 590 nm is 0 nm to 10 nm, and the thickness direction retardation value (Rth (590)) at a wavelength of 590 nm is from −10 nm to 10 nm.
In the polarizing plate of the present invention having such a transparent protective film, the retardation of the transparent protective film can be ignored in the design of optical compensation. For this reason, the polarizing plate of the present invention can be easily designed for optical compensation according to the type of the liquid crystal panel, and by using this polarizing plate, a liquid crystal display device excellent in viewing angle characteristics can be provided.
Furthermore, since the transparent protective film and the polarizer are bonded using a polyvinyl alcohol-based adhesive containing a metal compound colloid, a polarizing plate in which the occurrence of nicks is suppressed by the action of the metal compound colloid. Can be provided.

In a preferred polarizing plate of the present invention, the birefringent layer has an optical characteristic that the retardation value increases as the wavelength increases.
In another preferable polarizing plate of the present invention, the (meth) acrylic resin having the glutaric anhydride structure is a glutaric anhydride unit represented by the following general formula (1), and the general formula (2). Having an unsaturated carboxylic acid alkyl ester unit represented by:

In the general formula (1), R ¹ and R ² each independently represent a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms.
In the general formula (2), R ³ represents a hydrogen atom or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. R ⁴ represents a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 5 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 1 to 5 carbon atoms.

In another preferable polarizing plate of the present invention, the metal compound colloid has an average particle diameter of 1 nm to 100 nm.
Furthermore, in another preferable polarizing plate of the present invention, the polyvinyl alcohol-based adhesive contains 200 parts by mass or less of the metal compound colloid with respect to 100 parts by mass of the polyvinyl alcohol-based resin.
By using such a polyvinyl alcohol-based adhesive, it is possible to provide a polarizing plate in which generation of nicks is further suppressed.

  In another preferred polarizing plate of the present invention, the metal compound colloid is an alumina colloid. The alumina colloid is a metal compound colloid having a positive charge. This alumina colloid is particularly preferable because it has a greater effect of suppressing the occurrence of nicks than a metal colloid having a negative charge.

  In another preferable polarizing plate of the present invention, the polyvinyl alcohol-based adhesive further contains a crosslinking agent.

  In addition, the liquid crystal display device of the present invention includes any one of the above polarizing plates.

The polarizing plate of the present invention is laminated with a transparent protective film excellent in isotropy. Furthermore, the polarizing plate of the present invention has suppressed nicks, is optically uniform, and is excellent in durability.
Since the liquid crystal display device of the present invention includes the polarizing plate, it is excellent in image display and viewing angle characteristics.

The terms in the present invention have the following meanings.
(1) Total light transmittance:
The total light transmittance means a value measured by a method according to ASTM-D-1003.
(2) Birefringent layer:
The birefringent layer means an optical member having birefringence (refractive index anisotropy) in the plane and / or in the thickness direction. The birefringent layer includes, for example, a layer having an in-plane and / or thickness direction birefringence of 1 × 10 ⁻⁴ or more at 23 ° C. and a wavelength of 590 nm.
(3) Polarizer:
The polarizer means an optical member having a characteristic capable of converting natural light or polarized light into linearly polarized light.
(4) nx, ny, nz:
“Nx”, “ny”, and “nz” indicate refractive indexes in different directions. nx represents the refractive index in the direction in which the refractive index is maximum in the plane (referred to as the X-axis direction), and ny represents the refractive index in the direction perpendicular to the X-axis direction (referred to as the Y-axis direction) in the plane. , Nz represents the refractive index in the direction orthogonal to the X-axis direction and the Y-axis direction (referred to as the Z-axis direction).
Note that “nx = ny” includes not only the case where nx and ny are completely the same, but also the case where they are substantially the same. When nx and ny are substantially the same, for example, Re [590] is 0 nm to 10 nm, preferably 0 nm to 5 nm, and more preferably 0 nm to 3 nm.
“Ny = nz” includes not only the case where ny and nz are completely the same, but also the case where they are substantially the same. When ny and nz are substantially the same, for example, Re (590) -Rth (590) is −10 nm to 10 nm, preferably −5 nm to 5 nm, more preferably −3 nm to 3 nm. is there.
(5) Re (λ):
“In-plane retardation value (Re (λ))” means an in-plane retardation value measured at 23 ° C. with light of wavelength λ (nm).
Re (λ) can be obtained by Re (λ) = (nx−ny) × d, where d (nm) is the thickness of the object to be measured.
For example, Re (590) is an in-plane retardation value measured with light having a wavelength of 590 nm at 23 ° C.
(6) Rth (λ):
“Thickness direction retardation value (Rth (λ))” means a thickness direction retardation value measured with light having a wavelength of λ (nm) at 23 ° C. Rth (λ) can be obtained by Rth (λ) = (nx−nz) × d, where d (nm) is the thickness of the object to be measured.
For example, Rth (590) is a retardation value in the thickness direction measured with light having a wavelength of 590 nm at 23 ° C.
(7) Nz coefficient:
The “Nz coefficient” is a value calculated from Rth (λ) / Re (λ). In the present invention, the Nz coefficient is a value calculated from Rth (590) / Re (590) with 590 nm as a reference. The meanings of Rth (590) and Re (590) are as described above.
(8) Orthogonal:
“Orthogonal” includes the case where the angle formed by two optical axes is 90 ° ± 2 °, and preferably 90 ° ± 1 °.
(9) Resin:
“Resin” means a polymer of one structural unit or a polymer of two or more different structural units. This polymer contains a high polymer having a degree of polymerization (the total degree of polymerization of each structural unit in the case of containing two or more structural units) of 20 or more, and further a low weight having a polymerization degree of 2 or more and less than 20. Including coalescence (also called oligomer).
(10) (Meth) acrylic acid:
(Meth) acrylic acid means acrylic acid or methacrylic acid.

[Outline of Polarizing Plate of the Present Invention]
FIG. 1 shows the layer structure of the polarizing plate of the present invention. In the figure, for the sake of easy understanding, the size and ratio of each member are different from the actual ones (the same applies to other figures).
In the polarizing plate 1 of the present invention, a transparent protective film 2 containing a (meth) acrylic resin having a glutaric anhydride structure, a polarizer 3 and a birefringent layer 4 are laminated in this order.
Hereinafter, the (meth) acrylic resin having a glutaric anhydride structure may be simply referred to as “(meth) acrylic resin”.
A first adhesive layer 5 is provided between the transparent protective film 2 and the polarizer 3. The transparent protective film 2 and the polarizer 3 are attached via the first adhesive layer 5. The first adhesive layer 5 is composed of a polyvinyl alcohol-based adhesive containing a metal compound colloid.
A second adhesive layer 6 is provided between the polarizer 3 and the birefringent layer 4. The polarizer 3 and the birefringent layer 4 are attached via the second adhesive layer 6. This 2nd contact bonding layer 6 is comprised with arbitrary adhesives (an adhesive is the meaning containing the agent generally called an adhesive). For example, the second adhesive layer 6 may be composed of a polyvinyl alcohol-based adhesive containing the metal compound colloid of the present invention, or may be composed of an adhesive other than this adhesive. Examples of the adhesive other than the polyvinyl alcohol-based adhesive containing the metal compound colloid include an acrylic adhesive, a polyvinyl alcohol-based adhesive, and a urethane-based adhesive.
The birefringent layer 4 preferably has optical characteristics such that the retardation value increases as the wavelength increases. The polarizer 3 and the birefringent layer 4 are attached so that, for example, the absorption axis direction of the polarizer 3 and the slow axis direction of the birefringent layer 4 are orthogonal to each other.
In the present specification, the prefixes “first” and “second” are used for the sake of convenience to distinguish the terms, and the order of the terms given the “first” and “second” It does not mean or superiority or inferiority.

[Configuration example of LCD panel]
FIG. 2 shows an example of the configuration of the liquid crystal panel of the present invention.
The liquid crystal panel 10 includes a liquid crystal cell 9, a first polarizing plate 11, and a second polarizing plate 12. The first polarizing plate 11 is disposed, for example, on the viewing side of the liquid crystal cell 9. For example, the second polarizing plate 12 is disposed on the non-viewing side of the liquid crystal cell 9.
As at least one of the first polarizing plate 11 and the second polarizing plate 12, the polarizing plate 1 of the present invention as shown in FIG. 1 is used. Preferably, both the first polarizing plate 11 and the second polarizing plate 12 are the polarizing plate 1 of the present invention.
The 1st polarizing plate 11 and the 2nd polarizing plate 12 are arrange | positioned at the liquid crystal cell 9 so that the absorption-axis direction of a mutual polarizer may orthogonally cross, for example.
The first polarizing plate 11 and the second polarizing plate 12 are arranged in the liquid crystal cell 9 so that the birefringent layer is located between the polarizer and the liquid crystal cell 9.
In addition, the liquid crystal panel 10 of the present invention includes an arbitrary birefringent layer or an optical film between the first polarizing plate 11 and the liquid crystal cell 9 and / or between the second polarizing plate 12 and the liquid crystal cell 9. May be provided. Further, the members of the liquid crystal panel are bonded through an arbitrary adhesive layer.

  Examples of the liquid crystal cell include an active matrix type using a thin film transistor. The liquid crystal cell may be a simple matrix type as used in a super twist nematic liquid crystal display device.

In a liquid crystal cell, a liquid crystal layer is generally formed by a pair of substrates (not shown).
For example, in a liquid crystal cell, a space is formed by arranging a spacer between a pair of substrates. A liquid crystal layer in which liquid crystal molecules are enclosed is formed in this space. Of the pair of substrates, one substrate (active matrix substrate) includes, for example, a switching element (for example, TFT) for controlling the electro-optical characteristics of the liquid crystal and a scanning line for supplying a gate signal to the switching element. Provided. For example, a color filter is provided on the other of the pair of substrates. The color filter may be provided on the active matrix substrate.

  In the liquid crystal cell, the refractive index ellipsoid preferably satisfies the relationship of nx = ny <nz. A liquid crystal cell having a refractive index ellipsoid of nx = ny <nz has a vertical alignment (VA) mode, a twisted nematic (TN) mode, a vertical alignment type electric field control birefringence (ECB) according to the classification of liquid crystal alignment modes. ) Mode, optical compensation birefringence (OCB) mode, and the like. In the present invention, the liquid crystal alignment mode of the liquid crystal cell is preferably a vertical alignment mode (VA mode).

[Configuration Example of Liquid Crystal Display Device of the Present Invention]
The liquid crystal display device of the present invention comprises the liquid crystal panel of the present invention. The liquid crystal display device of the present invention may have the same configuration as a conventional liquid crystal display device except that the liquid crystal panel is included.
For example, the liquid crystal display device of the present invention includes at least the liquid crystal panel and a backlight unit disposed on one side of the liquid crystal panel. The backlight unit may be a direct type or a side light type.

  When the direct system is adopted, the backlight unit preferably includes at least a light source, a reflection film, a diffusion plate, a prism sheet, and a brightness enhancement film. When the sidelight method is adopted, the backlight unit preferably includes at least a light source, a reflection film, a diffusion plate, a prism sheet, a brightness enhancement film, a light guide plate, and a light reflector. Note that some of these members can be omitted or replaced with other members depending on the illumination method of the liquid crystal display device, the driving mode of the liquid crystal cell, and the like.

  The liquid crystal display device may be a transmissive type that irradiates light from the non-viewing side of the liquid crystal panel to view the screen, or a reflective type that irradiates light from the viewing side of the liquid crystal panel to view the screen. May be. Alternatively, the liquid crystal display device may be a transflective type having both transmissive and reflective properties.

  Applications of the liquid crystal display device of the present invention include, for example, OA equipment such as personal computer monitors, notebook personal computers, and copiers, mobile phones, watches, digital cameras, personal digital assistants (PDAs), portable devices such as portable game machines, and video cameras. , Household electrical equipment such as TVs and microwave ovens, back monitors, car navigation system monitors, in-vehicle equipment such as car audio, exhibition equipment such as information monitors for commercial stores, security equipment such as monitoring monitors, or Nursing care and medical equipment such as nursing monitors and medical monitors.

  A preferred application of the liquid crystal display device is a television. The screen size of the television is preferably a wide 17 type (373 mm × 224 mm) or more, more preferably a wide 23 type (499 mm × 300 mm) or more, and further preferably a wide 32 type (687 mm × 412 mm). That's it.

[Details of Each Member of Polarizing Plate of the Present Invention]
In the polarizing plate of the present invention, a transparent protective film containing a (meth) acrylic resin having a glutaric anhydride structure, a polarizer, and a birefringent layer are laminated in this order. Are bonded using a polyvinyl alcohol-based adhesive containing a metal compound colloid.

(About transparent protective film)
The transparent protective film is a film containing a (meth) acrylic resin having a glutaric anhydride structure as a main resin component.
A transparent protective film is so preferable that the total light transmittance is high. The total light transmittance of the transparent protective film is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more.

The in-plane retardation value (Re (590)) at a wavelength of 590 nm of the transparent protective film is 0 nm to 10 nm, preferably 0 nm to 5 nm, and more preferably 0 nm to 3 nm. Furthermore, the thickness direction retardation value (Rth (590)) at a wavelength of 590 nm of the transparent protective film is −10 nm to 10 nm, preferably −5 nm to 5 nm, and more preferably −3 nm to 3 nm. . Such a transparent protective film of Re (590) and Rth (590) has substantially no phase difference (that is, isotropic). For this reason, when designing a polarizing plate in order to obtain a liquid crystal display device excellent in viewing angle characteristics, the phase difference caused by the transparent protective film can be ignored. Therefore, in the production of the polarizing plate, it is possible to easily design optical compensation according to the type of the liquid crystal panel.
By using a (meth) acrylic resin having a glutaric anhydride structure, a film (that is, an isotropic film) having substantially no retardation as described above can be obtained.

  Examples of the glutaric anhydride structure include a glutaric anhydride unit represented by the following general formula (1).

However, in said general formula (1), R < ¹ > and R < ² > represents a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group each independently.
When the alkyl group having 1 to 5 carbon atoms has a substituent, examples of the substituent include halogen, —OH, —COOH, —NH ₂ , —SO ₃ H and the like.

  Furthermore, the (meth) acrylic resin preferably has the glutaric anhydride unit and an unsaturated carboxylic acid alkyl ester unit represented by the following general formula (2).

However, in the general formula (2), R ³ represents a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. R ⁴ represents a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 5 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 1 to 5 carbon atoms.
When the alkyl group having 1 to 5 carbon atoms, the aliphatic hydrocarbon group having 1 to 5 carbon atoms, or the alicyclic hydrocarbon group having 1 to 5 carbon atoms has a substituent, as the substituent, for example, Halogen, —OH, —COOH, —NH ₂ , —SO ₃ H and the like can be mentioned.

  As said (meth) acrylic-type resin, Unexamined-Japanese-Patent No. 2004-70290, Unexamined-Japanese-Patent No. 2004-70296, Unexamined-Japanese-Patent No. 2004-163924, Unexamined-Japanese-Patent No. 2004-292812, Unexamined-Japanese-Patent No. 2005-314534, for example. JP-A-2006-206881, JP-A-2006-265532, JP-A-2006-283013, JP-A-2006-299005, JP-A-2006-335902, etc. are used. be able to.

  In the (meth) acrylic resin, the content of the unit represented by the general formula (1) is preferably 5 to 50 mol%, more preferably 10 to 45 mol%, still more preferably. It is 15-40 mol%, Most preferably, it is 20-35 mol%, Most preferably, it is 25-35 mol%. When the content of this unit is less than 5 mol%, the effects expressed from the unit represented by the general formula (1) (for example, isotropic property, mechanical strength, adhesion to a polarizer, etc.) The effect that a transparent protective film excellent in the above can be obtained may not be sufficiently exhibited. Moreover, when content of the said unit exceeds 50 mol%, there exists a possibility that the transparent protective film sufficiently excellent in heat resistance and transparency may not be obtained, for example.

  In the (meth) acrylic resin, the content of the unit represented by the general formula (2) is preferably 50 to 95 mol%, more preferably 55 to 90 mol%, still more preferably. 60 to 85 mol%, particularly preferably 65 to 80 mol%, and most preferably 65 to 75 mol%. When the content of this unit is less than 50 mol%, an effect expressed from the unit represented by the general formula (2) (for example, a transparent protective film excellent in heat resistance and transparency is obtained. (Effect) may not be fully exhibited. On the other hand, if the content of the unit exceeds 95 mol%, the resin is brittle and easily cracked, and there is a possibility that a transparent protective film sufficiently excellent in mechanical strength may not be obtained.

The unit represented by the general formula (1) is preferably included in the unit represented by the following general formula (3).

However, ^{R 1} and ^{R 2} in the general formula (3) is the same as ^{R 1} and ^{R 2} in general formula (1).
In the general formulas (1) and (3), R ¹ and R ² are each independently preferably a hydrogen atom or a methyl group, and R ¹ and R ² are more preferably a methyl group.

  A (meth) acrylic resin having a glutaric anhydride unit represented by the general formula (1) and an unsaturated carboxylic acid alkyl ester unit represented by the general formula (2) is generally produced by the following method. can do.

  First, a copolymer (a) is synthesized by copolymerizing a (meth) acrylic acid ester monomer corresponding to the unit represented by the general formula (2) and an unsaturated carboxylic acid monomer. To do. Next, by heating the copolymer (a), the intramolecular structure of the structural unit of the (meth) acrylic acid ester monomer and the structural unit of the unsaturated carboxylic acid monomer in the copolymer (a) Perform a cyclization reaction. By this reaction, the unit of glutaric anhydride represented by the general formula (1) can be introduced into the copolymer (a). In this way, the (meth) acrylic resin can be produced.

  Examples of the (meth) acrylate monomer include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and (meth) acrylic. T-butyl acid, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth ) 3-hydroxypropyl acrylate, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate, 2,3,4,5-tetrahydroxypentyl (meth) acrylate, and the like. These may be used alone or in combination of two or more. Among these, since it is excellent in thermal stability, it is preferable to use methyl (meth) acrylate, and methyl methacrylate is more preferable.

  Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, α-substituted acrylic acid, α-substituted methacrylic acid, and the like. These may be used alone or in combination of two or more. Among these, the unsaturated carboxylic acid monomer is preferably acrylic acid or methacrylic acid.

The polymerization method for synthesizing the copolymer (a) basically includes a bulk polymerization method, a solution polymerization method, a suspension polymerization method, an emulsion polymerization method, and the like.
In the synthesis of the copolymer (a), the blending ratio of the (meth) acrylic acid ester monomer is preferably 55 to 85% by weight when the sum of the blended monomers is 100% by weight. More preferably, it is 60-80 mass%. In addition, the blending ratio of the unsaturated carboxylic acid monomer is preferably 15 to 45% by weight, more preferably 20 to 40% by weight, when the sum of the blended monomers is 100% by weight. By setting the blending ratio of the unsaturated carboxylic acid monomer to 15 to 45% by mass, the content of the unit represented by the general formula (1) obtained by heating the copolymer (a) is the above. 5 to 50 mol%.

  Examples of the intramolecular cyclization reaction of the copolymer (a) include dealcoholization reaction, dehydration reaction, and complex reaction thereof. The method for heating the copolymer (a) when performing the intramolecular cyclization reaction is not particularly limited. As this method, for example, the copolymer (a) is passed through a heated extruder having a vent, or the copolymer (a) is heated in an apparatus that can be heated and degassed in a nitrogen stream or under reduced pressure. The method is preferred.

In the molecule of the (meth) acrylic resin, a structural unit other than the unit represented by the general formula (1) and the unit represented by the general formula (2) (hereinafter sometimes referred to as other structural units). May be included.
The other structural unit has a structure that does not belong to any of the general formulas (1) to (3), and is preferably a vinyl monomer.

  Examples of the other structural unit include a structural unit derived from an unsaturated carboxylic acid monomer that is not involved in the intramolecular cyclization reaction. Content of the structural unit of this unsaturated carboxylic acid is 0-10 mass%, Preferably it is 0-5 mass%, More preferably, it is 0-1 mass%. By making this other structural unit 10 mass% or less, the transparent protective film excellent in heat resistance and transparency can be obtained.

  In addition, examples of the other structural units include structural units derived from other vinyl monomers that can be copolymerized with (meth) acrylic acid ester monomers and / or unsaturated carboxylic acids. Examples of the other vinyl monomers include acrylonitrile, methacrylonitrile, allyl glycidyl ether, maleic anhydride, itaconic anhydride, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, acrylamide, and methacrylamide. N-methylacrylamide, butoxymethylacrylamide, N-propylmethacrylamide, aminoethyl acrylate, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, cyclohexylaminoethyl methacrylate, phenylaminoethyl methacrylate N-vinylethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine, 2-isopropenyloxazoline, - vinyl oxazoline, 2-acryloyl-oxazoline, 2-styryl oxazoline, N- phenylmaleimide, styrene and α- methyl styrene. These may be used alone or in combination of two or more.

  Among the other vinyl monomers, styrene monomers such as styrene and α-methylstyrene are preferable. In the synthesis of the copolymer (a), the blending ratio of the styrene monomer is preferably 0 to the total amount of the (meth) acrylic acid ester monomer and the unsaturated carboxylic acid monomer. It is 1 mass%, More preferably, it is 0-0.1 mass%. By forming a (meth) acrylic resin into which a structural unit derived from a styrene monomer has been introduced, a transparent protective film excellent in isotropicity and transparency can be obtained.

  The (meth) acrylic resin has a mass average molecular weight (also referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably 50,000. ~ 500,000, most preferably 60000-150,000. If a (meth) acrylic resin having a mass average molecular weight outside the above range is used, the effects of the present invention may not be exhibited sufficiently.

  The glass transition temperature (Tg) of the (meth) acrylic resin is preferably 110 ° C. or higher, more preferably 115 ° C. or higher, still more preferably 120 ° C. or higher, and particularly preferably 125 ° C. or higher. Most preferably, it is 130 ° C. or higher. By forming the (meth) acrylic resin having a Tg of 110 ° C. or higher, a transparent protective film excellent in heat resistance and durability can be obtained. The upper limit value of Tg of the (meth) acrylic resin is not particularly limited, but is preferably 170 ° C. or less from the viewpoint of moldability. The glass transition temperature can be determined by, for example, the DSC method according to JIS K 7121 (1987).

  The material for forming the transparent protective film of the present invention contains the (meth) acrylic resin as a main resin component. By forming the forming material into a film, the transparent protective film of the present invention can be obtained. The forming material may contain other thermoplastic resin or thermosetting resin in addition to the (meth) acrylic resin, if necessary. Other thermoplastic resins and thermosetting resins are thermodynamically compatible with the (meth) acrylic resin and improve the transparency and mechanical strength of the resulting transparent protective film.

  In the resin component of the material for forming the transparent protective film, the blending ratio of the (meth) acrylic resin is preferably 50 to 100% by mass, more preferably 60 to 100% by mass, and further preferably 70 to 100%. It is mass%, Most preferably, it is 80-100 mass%. If the blending ratio of the (meth) acrylic resin is less than 50% by mass, a transparent protective film excellent in isotropy, heat resistance and transparency may not be obtained.

  Examples of the other thermoplastic resins include olefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, poly (4-methyl-1-pentene); halogen-containing resins such as vinyl chloride; polymethacrylic acid Other acrylic resins such as methyl; styrene resins such as polystyrene, styrene-methyl methacrylate copolymer, styrene-acrylonitrile copolymer, acrylonitrile-butadiene-styrene block copolymer; polyethylene terephthalate, polybutylene terephthalate, polyethylene Polyester resins such as naphthalate; Polyamide resins such as nylon 6, nylon 66, nylon 610; Polyacetal; Polycarbonate; Polyphenylene oxide; Polyphenylene sulfide; Polyether ether keto ; Polysulfone; polyether sulfone; polyoxyethylene benzylidene alkylene; polyamideimide; polybutadiene rubber; ABS resin blended with acrylic rubber; rubber-like polymer such as ASA resins, and the like.

Examples of the thermosetting resin include phenolic resins, melamine resins, silicone resins, and epoxy resins.
Said other thermoplastic resin and thermosetting resin are mix | blended in the range which does not impair the objective of this invention.
Furthermore, the material for forming the transparent protective film may contain any appropriate additive. Additives include hindered phenol, benzotriazole, benzophenone, benzoate, and cyanoacrylate UV absorbers or antioxidants; higher fatty acids, acid esters, acid amides, higher alcohols and other lubricants or plastics Agents: Montanic acid and its salts, its esters, their half esters, and mold release agents such as stearyl alcohol, stearamide, ethylene wax; anti-coloring agents such as phosphites and hypophosphites; Examples include flame retardants or non-halogen flame retardants such as phosphorus or silicone; antistatic agents such as amine, sulfonic acid, and polyether; and colorants such as pigments. These are blended within a range that does not affect the isotropy and transparency, which are the characteristics of the transparent protective film of the present invention. Practically, the blending ratio of the additive is preferably 10% by mass or less in the forming material.

Furthermore, the transparent protective film forming material may further contain acrylic elastic particles. The transparent protective film obtained by forming the forming material containing the acrylic elastic particles has excellent toughness.
The acrylic elastic particles preferably include a rubbery polymer. The rubber-like polymer contains an acrylic component (raw material monomer) such as ethyl acrylate and butyl acrylate as an essential component, and may contain other preferable optional components (raw material monomer). Examples of the optional component include silicone components such as dimethylsiloxane and phenylmethylsiloxane; styrene components such as styrene and α-methylstyrene; nitrile components such as acrylonitrile and methacrylonitrile; conjugated diene components such as butanediene and isoprene; urethane component; Examples include ethylene component; propylene component; isobutene component. Among these optional components, the rubbery polymer preferably contains at least one selected from a silicone component, a styrene component, a nitrile component, and a conjugated diene component. The rubber polymer is a polymer obtained by polymerizing one kind of raw material monomer, a copolymer obtained by copolymerizing two or more kinds of raw material monomers (preferably, the above essential components and optional components), or a single kind of a single polymer. It is comprised with the mixture and the mixture of the said 2 or more types of copolymer. More preferably, the rubbery polymer is the two or more kinds of copolymers. The rubbery polymer composed of two or more kinds of copolymers is, for example, a copolymer of an acrylic component and a silicone component, a copolymer of an acrylic component and a styrene component, a copolymer of an acrylic component and a conjugated diene component , Three kinds of copolymers of an acrylic component, a silicone component, and a styrene component.
The rubbery polymer may contain a crosslinkable component such as divinylbenzene, allyl acrylate, butylene glycol diacrylate as an optional component.

  The rubbery polymer preferably contains an acrylic component and a styrene component. The acrylic component (particularly butyl acrylate) is extremely effective in improving toughness. By including a rubbery polymer obtained by copolymerizing a styrene component with the acrylic component, the refractive index of the acrylic elastic particles can be adjusted.

  The difference between the refractive index of the acrylic elastic particles and the refractive index of the (meth) acrylic resin is preferably 0.01 or less. By forming a forming material containing acrylic elastic particles having a difference in refractive index and a (meth) acrylic resin, a transparent protective film excellent in isotropicity and transparency can be obtained. Any appropriate method can be adopted as a method for setting the difference in refractive index to 0.01 or less. As this method, for example, a method of adjusting the content ratio of each monomer of the (meth) acrylic resin, or a blending ratio of two or more rubber polymers in the acrylic elastic particles or a rubber polymer And a method of adjusting the composition ratio of the raw material monomers. In particular, when an acrylic component and a styrene component are copolymerized, an acrylic elastic particle having a small refractive index difference from the (meth) acrylic resin can be obtained by adjusting the copolymerization ratio.

  The average particle diameter of the acrylic elastic particles is preferably 70 nm to 300 nm, more preferably 100 nm to 200 nm. By forming a forming material containing acrylic elastic particles having an average particle diameter of 70 nm or more, a transparent protective film excellent in toughness and impact resistance can be obtained. Moreover, the heat resistant fall of a transparent protective film can be suppressed by using an acrylic elastic body particle | grain with an average particle diameter of 300 nm or less.

  The mixing ratio of the acrylic elastic particles is 40% by mass or less, preferably 7 to 40% by mass, and more preferably 12 to 20% by mass in the forming material. By forming a forming material containing acrylic elastomer particles having such a blending ratio, a transparent protective film having appropriate flexibility and excellent workability such as winding property and heat resistance can be obtained.

  The transparent protective film of the present invention can be obtained by forming a forming material containing the (meth) acrylic resin or the like by a melt extrusion molding method or a solution casting method. The strength of the transparent protective film can be improved by subjecting the film after the film formation to a stretching treatment. The stretching treatment may cause a slight phase difference in the transparent protective film. However, if a phase difference adjusting agent is added to the forming material, it is possible to suppress a phase difference from occurring in the film due to the stretching treatment.

The thickness of the transparent protective film of the present invention can be determined as appropriate. Considering its strength, handleability, etc., the thickness of the transparent protective film is 1 μm to 5000 μm, preferably 1 μm to 300 μm, more preferably 5 μm to 200 μm. In particular, the thickness of the transparent protective film is preferably 5 μm to 100 μm because the polarizing plate can be formed thin.
Moreover, since the transparent protective film of this invention satisfies the moisture permeability of 300 g / m < ² > * 24hr or less, it is excellent in durability. The moisture permeability of the transparent protective film is preferably 250 g / m ² · 24 hr or less, more preferably 200 g / m ² · 24 hr or less.
In addition, you may surface-treat the surface of the said transparent protective film as needed. By performing the surface treatment, the adhesiveness between the transparent protective film and the polarizer can be improved.
As the surface treatment method, a conventionally known method can be used. Examples of the surface treatment include electrical treatment such as corona discharge treatment and spark treatment; plasma treatment under low pressure or normal pressure; ultraviolet irradiation treatment in the presence or absence of ozone; acid treatment with chromic acid or the like. Alkali saponification treatment; flame treatment; treatment of applying a silane primer, a titanium primer, or the like.
Moreover, you may provide an easily bonding layer in the surface or / and the back surface of a transparent protective film. By providing the easy adhesion layer, the affinity with the polyvinyl alcohol-based adhesive containing the metal compound colloid can be improved. The easy-adhesion layer is formed by coating a transparent protective film with a copolymer polyester, a urethane-modified copolymer polyester, a copolymer polyester having a carboxyl group and / or a sulfonic acid group, a solution such as polyvinyl alcohol, or an aqueous dispersion. It can be formed by drying. Moreover, the said easily bonding layer can also be formed by forming resin layers, such as a cellulose ester resin, in a transparent protective film, and performing an alkali saponification process to this resin layer.

(About polarizers)
The polarizer used for the polarizing plate of this invention is not specifically limited, A conventionally well-known polarizer can be used. Examples of the polarizer include a dyed stretched film dyed with a dichroic material and a liquid crystal film formed with a liquid crystalline compound having absorption dichroism.
The above-mentioned dyed stretched film is preferably used as the polarizer because it can be appropriately bonded to the transparent protective film via a polyvinyl alcohol-based adhesive containing a metal compound colloid.

The dyed stretched film is generally a stretched film obtained by stretching a film mainly composed of a hydrophilic resin containing iodine or a dichroic dye.
Examples of the film mainly containing the hydrophilic resin include polyvinyl alcohol films such as polyvinyl alcohol and partially formalized polyvinyl alcohol, polyethylene terephthalate films, ethylene / vinyl acetate copolymer films, and partially saponified films thereof. Etc. In addition to these, polyene oriented films such as a dehydrated polyvinyl alcohol film and a dehydrochlorinated polyvinyl chloride film can also be used. Among these, since it is excellent in the dyeability by a dichroic substance, a polyvinyl alcohol-type film is preferable. Polyvinyl alcohol is a resin obtained by saponifying polyvinyl acetate obtained by polymerizing vinyl acetate. Furthermore, the polyvinyl alcohol film includes a resin film containing a component copolymerizable with vinyl acetate such as unsaturated carboxylic acid, olefins, vinyl ethers, and unsaturated sulfonates in the polyvinyl alcohol. .
The dyed stretched film is a swelling process for swelling a long unstretched film mainly composed of a polyvinyl alcohol resin, a dyeing process for impregnating the film with a dichroic substance such as iodine, and a crosslinking agent containing boron. It can obtain by the manufacturing method which has each process of the bridge | crosslinking process which bridge | crosslinks, and the extending | stretching process extended | stretched by a predetermined magnification. An appropriate value is selected as appropriate for the thickness of the polarizer. In general, the thickness of the polarizer is preferably 5 μm to 50 μm, more preferably 10 μm to 30 μm.

(About birefringent layers)
A conventionally well-known thing can be used for the birefringent layer used for the polarizing plate of this invention. Since a polarizing plate having excellent viewing angle characteristics can be formed, it is preferable to use a birefringent layer having optical characteristics in which the retardation value increases as the wavelength increases. Such optical characteristics are also called reverse wavelength dispersion (hereinafter, this optical characteristic may be referred to as “reverse wavelength dispersion”). In such a reverse wavelength dispersive birefringent layer, the in-plane retardation value (Re (λ)) and / or the thickness direction retardation value (Rth (λ)) satisfy the following relationship. Re (450) <Re (550) <Re (650). Rth (450) <Rth (550) <Rth (650).
The ratio of Re (450) to Re (550) (Re (450) / Re (550)) of the birefringent layer is preferably 0.95 or less, more preferably 0.70 to 0.90. More preferably, it is 0.75-0.90, Most preferably, it is 0.80-0.90.
The ratio of Re (650) to Re (550) (Re (650) / Re (550)) of the birefringent layer is preferably 1.05 or more, more preferably 1.05 to 1.20. More preferably, it is 1.05-1.15, Most preferably, it is 1.05-1.10.

The Re (590) of the birefringent layer can be appropriately designed by, for example, adjusting the thickness of the birefringent layer. The Re (590) of the birefringent layer is preferably 80 nm to 220 nm, more preferably 100 nm to 200 nm, and still more preferably 110 nm to 180 nm.
The Nz coefficient of the birefringent layer is preferably 1 to 2, more preferably 1.0 to 1.8, and still more preferably 1.0 to 1.5.
By using a birefringent layer having the above optical characteristics (Re (λ), Rth (λ) and Nz coefficient), a polarizing plate capable of satisfactorily compensating for the axial misalignment of the polarizer and the thickness direction retardation of the liquid crystal cell can be obtained. obtain.

The birefringent layer preferably has a refractive index ellipsoid of nx> ny = nz or nx>ny> nz. In particular, the birefringent layer preferably has the reverse wavelength dispersion and is optically biaxial (for example, the refractive index ellipsoid is nx>ny> nz). By using such a birefringent layer, a polarizing plate capable of satisfactorily compensating for the axial misalignment of the polarizer and the thickness direction retardation of the liquid crystal cell can be obtained.
The thickness of the birefringent layer is appropriately adjusted in designing the retardation value and the like, but is usually in the range of 1 μm to 150 μm, preferably 5 μm to 150 μm, more preferably 5 μm to 120 μm, More preferably, it is 10-100 micrometers.

  The material for forming the birefringent layer is not particularly limited. Preferably, the forming material itself exhibits reverse wavelength dispersion.

  As a material for forming the birefringent layer, for example, a non-liquid crystalline material, particularly a non-liquid crystalline polymer is preferable. Such a non-liquid crystalline material can form a film having optical uniaxiality of nx> nz or ny> nz depending on its own properties, unlike the liquid crystalline material. Furthermore, a film having optical biaxiality such as nx> ny> nz can be obtained by subjecting this film to stretching treatment or the like.

  Examples of the material for forming the birefringent layer having reverse wavelength dispersion include a modified cellulose resin and a modified polyvinyl alcohol resin. The film containing the resin exhibits reverse wavelength dispersion. By subjecting this film to stretching, a film having optical biaxiality such as nx> ny> nz can be obtained.

  Examples of the cellulose resin include cellulose resins described in paragraphs [0106] to [0112] of JP-A No. 2002-82225, and paragraphs [0021] to [0034] of Japanese Patent No. 34507779. Examples include the cellulose-based resins described.

  Moreover, the cellulose resin substituted by the acetyl group and the propionyl group can also be used. In this cellulosic polymer, the degree of substitution of acetyl groups can be indicated by “degree of acetyl substitution (DSac)”. The degree of acetyl substitution (DSac) is an index indicating how many of the three hydroxyl groups present in the repeating unit of cellulose are substituted with acetyl groups on average. In the cellulosic resin, the degree of substitution of the propionyl group can be represented by “degree of propionyl substitution (DSpr)”. The propionyl substitution degree (DSpr) is an index indicating how many of the three hydroxyl groups present in the repeating unit of cellulose are substituted with propionyl groups on average. The degree of acetyl substitution (DSac) and the degree of propionyl substitution (DSpr) can be determined by the methods described in JP-A No. 2003-315538, [0016] to [0019].

  As the cellulose resin, those having an acetyl substitution degree (DSac) and a propionyl substitution degree (DSpr) satisfying 2.0 ≦ DSac + DSpr ≦ 3.0 are used. The lower limit value of the DSac + DSpr is preferably 2.3 or more, more preferably 2.6 or more. The upper limit value of the DSac + DSpr is preferably 2.9 or less, and more preferably 2.8 or less.

As the cellulose resin, one having a propionyl substitution degree (DSpr) satisfying 1.0 ≦ DSpr ≦ 3.0 is used. The lower limit value of the DSpr is preferably 2 or more, more preferably 2.5 or more. The upper limit value of DSpr is preferably 2.9 or less, more preferably 2.8 or less.
The said cellulose resin may have other substituents other than an acetyl group and a propionyl group. Examples of the other substituent include an ether group such as an ester group, an alkyl ether group, and an alkylene ether group.
The number average molecular weight of the cellulose resin is preferably 5,000 to 100,000, more preferably 10,000 to 70,000.

  Moreover, as a modified polyvinyl alcohol-type resin, the polymer which has at least any one side chain of the side chain represented by the following general formula (4) or general formula (5) is mentioned.

In formula (4), ^{R 5} represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. R ⁶ and R ¹⁰ are each independently a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, a linear or branched alkoxy group having 1 to 4 carbon atoms, carbon It represents a linear or branched thioalkoxy group of formulas 1 to 4, a halogen, a nitro group, an amino group, a hydroxyl group or a thiol group (however, R ⁶ and R ¹⁰ are not hydrogen atoms at the same time). R ^{7 to} R ⁹ each independently represent a hydrogen atom or a substituent.

In the general formula (5), R ¹¹ represents a hydrogen atom or an alkyl group having 1 to 8 carbon atoms. A ¹ represents a naphthyl group which may have a substituent, an anthranyl group which may have a substituent, or a phenanthrenyl group which may have a substituent. One or more carbon atoms among the carbon atoms constituting the naphthyl group, the anthranyl group, or the phenanthrenyl group may be substituted with a nitrogen atom.

  Moreover, as a modified polyvinyl alcohol-type resin, the polymer which has a repeating unit represented by following General formula (6) is mentioned.

In the general formula (6), R ¹² represents a hydrogen atom, a linear or branched alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted phenyl group. R ¹³ , A ² and A ³ are each independently a hydrogen atom, halogen, a linear or branched alkyl group having 1 to 4 carbon atoms, or a linear or branched structure having 1 to 4 carbon atoms. A halogenated alkyl group, a linear or branched alkoxy group having 1 to 4 carbon atoms, an alkoxycarbonyl group, an acyloxy group, an amino group, an azide group, a nitro group, a cyano group, or a hydroxyl group (provided that R ¹³ is not a hydrogen atom).

  The film containing the polymer having any of the general formulas (4) to (6) exhibits reverse wavelength dispersion. Films using this polymer are described in paragraphs [0060] to [0084] of JP-A-2006-65258, paragraphs [0029] to [0087] of JP-A-2007-161993, and the like. The matters described in the above publication are deemed to have been described in the present specification, and the items to be described are omitted.

  The birefringent layer is obtained by producing (forming) a film of the forming material containing the non-liquid crystalline polymer by any appropriate molding method, and subjecting the film to stretching treatment as necessary. Examples of the molding method include compression molding method, transfer molding method, injection molding method, extrusion molding method, blow molding method, powder molding method, FRP molding method, solvent casting method and the like. Preferably, the molding method is a solvent casting method or an extrusion molding method. In the solvent casting method, for example, a concentrated solution (dope) in which a forming material containing a non-liquid crystalline polymer and other components (additives, etc.) is dissolved in a solvent is defoamed, and then the endless stainless belt or rotating drum is used. It is a method of casting a film on the surface and evaporating the solvent to form a film. The extrusion molding method is, for example, a method in which the forming material is heated and melted, extruded onto the surface of a casting roll using a T die or the like, and cooled to form a film. By employing the above method, a birefringent layer having excellent thickness uniformity can be obtained.

  Any appropriate stretching method may be employed for the stretching treatment depending on the purpose. Examples of the stretching method include a longitudinal uniaxial stretching method, a transverse uniaxial stretching method, a longitudinal and transverse simultaneous biaxial stretching method, and a longitudinal and transverse sequential biaxial stretching method. Examples of the stretching machine that performs this include a roll stretching machine, a tenter stretching machine, and a biaxial stretching machine. Preferably, the stretching machine includes a temperature control unit. When stretching by heating, the internal temperature of the stretching machine may be changed continuously or stepwise. The stretching direction may be the longitudinal direction (MD direction) of the film or the width direction (TD direction) of the film. Moreover, you may extend | stretch in the diagonal direction (diagonal extending | stretching) using the extending | stretching method of FIG. 1 of Unexamined-Japanese-Patent No. 2003-262721.

  The temperature for stretching (stretching temperature) is appropriately set according to the type of film. The stretching is preferably carried out in the range of the glass transition temperature (Tg) of the film ± 30 ° C. By stretching under such conditions, a film having a uniform retardation value can be obtained, and crystallization (white turbidity) of the film can be prevented. Specifically, the stretching temperature is preferably 100 ° C to 180 ° C, more preferably 120 ° C to 160 ° C.

  The means for controlling the stretching temperature is not particularly limited, and for example, an air circulation type constant temperature oven in which hot air or cold air circulates, a heater using microwaves or far infrared rays, a roll heated for temperature adjustment, or heated. Heat pipe rolls, heated metal belts and the like.

  The draw ratio of the film is appropriately set according to the purpose. The draw ratio is preferably more than 1 time and 3 times or less, more preferably more than 1 time and 2.5 times or less, and particularly preferably 1.1 times to 2.0 times. Moreover, the feed rate at the time of stretching is not particularly limited, but is preferably 0.5 m / min to 30 m / min from the viewpoint of mechanical accuracy, stability, and the like.

  In addition, it is preferable that the film containing the cellulose resin substituted with the acetyl group and the propionyl group is subjected to stretching treatment by a sequential biaxial stretching method. A film containing such a cellulose-based resin becomes a film exhibiting optical biaxiality by biaxial stretching. In the sequential biaxial stretching method, the film is stretched in the longitudinal direction (or width direction) and then stretched in the width direction (or longitudinal direction).

(About polyvinyl alcohol adhesive)
The polyvinyl alcohol-based adhesive containing the metal compound colloid used in the polarizing plate of the present invention is a resin solution containing a polyvinyl alcohol-based resin and a metal compound colloid, and further includes a crosslinking agent. The metal compound colloid preferably has an average particle diameter of 1 nm to 100 nm.

  Examples of the polyvinyl alcohol resin include polyvinyl alcohol resins and modified polyvinyl alcohol resins having an acetoacetyl group. Examples of the modified polyvinyl alcohol-based resin having an acetoacetyl group include, for example, “GOHSENOL Z series” manufactured by Nippon Synthetic Chemical Co., Ltd., “GOHSENOL NH series” manufactured by the company, and “GO Cefaimer Z series ”.

  Examples of the polyvinyl alcohol-based resin include a saponified product of polyvinyl acetate and a derivative thereof; a saponified product of a copolymer of vinyl acetate and a monomer copolymerizable therewith; acetalization, urethanization of polyvinyl alcohol, And modified polyvinyl alcohols such as etherification, grafting, and phosphoric esterification. Examples of the copolymerizable monomer include unsaturated carboxylic acids such as maleic acid, maleic anhydride, fumaric acid, crotonic acid, itaconic acid, acrylic acid, methacrylic acid, and esters thereof; ethylene, propylene, and the like. Α-olefin containing: allyl sulfonic acid, methallyl sulfonic acid, sodium allyl sulfonate, sodium methallyl sulfonate, sodium sulfonate, sodium sulfonate monoalkylmalate, sodium alkylsulfonate maleate, alkali salt of acrylamide alkyl sulfonate And sulfonic acid group-containing monomers such as N-methylolacrylamide; N-vinylpyrrolidone and derivatives thereof.

  The average degree of polymerization of the polyvinyl alcohol resin is preferably 100 to 5000, more preferably 1000 to 4000, from the viewpoint of adhesiveness. The average degree of saponification of the polyvinyl alcohol resin is preferably 85 to 100 mol%, more preferably 90 to 100 mol%, from the viewpoint of adhesiveness.

  The modified polyvinyl alcohol-based resin having an acetoacetyl group can be obtained, for example, by reacting a polyvinyl alcohol-based resin and diketene by an arbitrary method. Specifically, for example, (a) a method of adding diketene to a dispersion in which a polyvinyl alcohol resin is dispersed in a solvent such as acetic acid, and (b) a polyvinyl alcohol resin in a solvent such as dimethylformamide or dioxane. Examples thereof include a method in which diketene is added to the dissolved solution, and a method (c) in which a diketene gas or liquid diketene is brought into direct contact with the polyvinyl alcohol resin.

  The degree of acetoacetyl modification of the modified polyvinyl alcohol resin having an acetoacetyl group is, for example, 0.1 mol% or more. By using a modified polyvinyl alcohol resin having a degree of acetoacetyl group modification in the above range, an adhesive having better water resistance can be obtained. The degree of modification of the acetoacetyl group is preferably 0.1 to 40 mol%, more preferably 1 to 20 mol%, and particularly preferably 2 to 7 mol%. The degree of acetoacetyl modification is a value measured by, for example, a nuclear magnetic resonance (NMR) method.

  Any appropriate crosslinking agent can be adopted as the crosslinking agent. The cross-linking agent is preferably a compound having at least two functional groups having reactivity with the polyvinyl alcohol resin. Examples of the crosslinking agent include alkylene diamines having two alkylene groups and amino groups such as ethylene diamine, triethylene diamine, and hexamethylene diamine; tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane tolylene diisocyanate adduct, tolyl. Phenylmethane triisocyanate, methylenebis (4-phenyl) methane triisocyanate, isophorone diisocyanate, and isocyanates such as ketoxime block product or phenol block product; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin diglycidyl ether Glycerin triglycidyl ether, 1,6-hexanediol diglycidyl ether, trimer Epoxys such as roll propane triglycidyl ether, diglycidyl aniline, diglycidyl amine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde; glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, maleindialdehyde Dialdehydes such as phthaldialdehyde; aminoformaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetoguanamine, and condensates of benzoguanamine and formaldehyde; sodium, potassium, magnesium, calcium And salts of metals such as aluminum, iron and nickel, and oxides thereof. Of these, aminoformaldehyde resins and dialdehydes are preferred. The amino formaldehyde resin is preferably a compound having a methylol group. Glyoxal is preferred as the dialdehyde. Among them, a compound having a methylol group is preferable, and methylol melamine is particularly preferable. Examples of the aldehyde compound include a product name “Glyoxal” manufactured by Nippon Synthetic Chemical Co., Ltd., a product name “SECARETZ 755” manufactured by OMNOVA, and the like. Examples of the methylol compound include trade name “Watersol Series” manufactured by Dainippon Ink Co., Ltd.

  The blending ratio of the crosslinking agent is, for example, 1 to 60 parts by mass with respect to 100 parts by mass of the polyvinyl alcohol resin (preferably a modified polyvinyl alcohol resin having an acetoacetyl group). An adhesive having a crosslinking agent content in the above range can form an adhesive layer excellent in transparency, adhesiveness, and water resistance. The upper limit of the blending ratio of the crosslinking agent is preferably 50 parts by mass, more preferably 30 parts by mass, still more preferably 15 parts by mass, particularly preferably 10 parts by mass, and most preferably 7 parts by mass. Part. The lower limit of the blending amount is preferably 5 parts by mass, more preferably 10 parts by mass, and still more preferably 20 parts by mass. In addition, since the polyvinyl alcohol-type adhesive of this invention contains the metal compound colloid, even if it is a case where many crosslinking agents are mix | blended, it is excellent in stability.

  Next, the metal compound colloid may be, for example, one in which fine particles are dispersed in a dispersion medium, and is electrostatically stabilized due to mutual repulsion of the same kind of charge of the fine particles, and has permanent stability. It may be a thing. The average particle diameter of the metal compound fine particles (colloid) is not particularly limited, but is preferably 1 nm to 100 nm, and more preferably 1 nm to 50 nm. Since the metal compound colloid having such an average particle diameter can be dispersed substantially uniformly in the dispersion medium, the adhesive containing the colloid is excellent in adhesiveness, and has a nick at the interface between the transparent protective film and the polarizer. Generation can be suppressed.

  Any appropriate compound can be adopted as the metal compound. Examples of the metal compound include metal oxides such as alumina, silica, zirconia, and titania; metal salts such as aluminum silicate, calcium carbonate, magnesium silicate, zinc carbonate, barium carbonate, and calcium phosphate; celite, talc, clay, Examples include minerals such as kaolin. The metal compound is preferably alumina.

  The metal compound colloid is present, for example, in a colloid solution in which the metal compound is dispersed in a dispersion medium. Examples of the dispersion medium include water and alcohols. The solid content concentration in the colloidal solution is, for example, 1 to 50% by mass. The colloidal solution may contain an acid (for example, nitric acid, hydrochloric acid, acetic acid, etc.) as a stabilizer.

  Metal compound colloids are electrostatically stable and can be divided into colloids having a positive charge and colloids having a negative charge. Positive charge and negative charge are distinguished by the charge state of the colloidal surface charge in the colloidal solution. The charge of the metal compound colloid can be confirmed, for example, by measuring the zeta potential. The surface charge of a metal compound colloid generally varies with pH. Therefore, the charge of the colloidal solution is affected by the pH of the prepared adhesive (resin solution). The pH of the adhesive is usually 2 to 6, preferably 2.5 to 5, more preferably 3 to 5, and further preferably 3.5 to 4.5. In the present invention, the adhesive containing a metal compound colloid having a positive charge can suppress the occurrence of nicks more than the adhesive containing a metal compound colloid having a negative charge. Examples of the positively charged metal compound colloid include alumina colloid and titania colloid, and alumina colloid is particularly preferable.

  The blending ratio (in terms of solid content) of the metal compound colloid is preferably 200 parts by mass or less with respect to 100 parts by mass of the polyvinyl alcohol resin. The adhesive having the above blending ratio can more appropriately suppress the occurrence of nicks while ensuring adhesiveness. The blending ratio of the metal distribution compound colloid is more preferably 10 to 200 parts by mass, still more preferably 20 to 175 parts by mass, and particularly preferably 30 to 150 parts by mass.

  The viscosity of the polyvinyl alcohol-based adhesive (resin solution) containing the metal colloid is not particularly limited, but is preferably 1 to 50 mPa · s. In general, the occurrence of nicks increases as the viscosity of the adhesive decreases. However, the polyvinyl alcohol adhesive of the present invention can suppress the occurrence of nicks even with a relatively low viscosity as described above.

  The polyvinyl alcohol-based adhesive is prepared by mixing a polyvinyl alcohol-based resin and a cross-linking agent in a dispersion medium and blending a metal compound therein. Further, in the polyvinyl alcohol adhesive, there are coupling agents such as silane coupling agents and titanium coupling agents, tackifiers, UV absorbers, antioxidants, heat stabilizers, hydrolysis stabilizers, and the like. It may be included. Although the metal compound colloid of the present invention is a non-conductive material, the colloid may contain fine particles of a conductive substance.

  The application of the polyvinyl alcohol-based adhesive containing the metal colloid may be performed on the adhesive surface of the polarizer or the transparent protective film, or may be performed on the adhesive surface of both the polarizer and the transparent protective film. . The adhesive is applied so as to have a dry thickness of 10 nm to 300 nm, preferably 10 nm to 200 nm, more preferably 20 nm to 150 nm.

Next, examples and comparative examples of the present invention are shown. In addition, this invention is not limited by the following Example and comparative example.
Various measurements and the like in the following Examples and Comparative Examples were performed by the following methods.
(1) Measurement of Re (λ), nx, ny and nz:
Using a trade name “KOBRA21-ADH” manufactured by Oji Scientific Instruments, measurement was performed at 23 ° C. and at each wavelength λ nm. In addition, the value measured using the Abbe refractometer (The product made from Atago Co., Ltd. product name "DR-M4") was used for the average refractive index.
(2) Measurement of thickness:
When the thickness was less than 10 μm, the thickness was measured using a thin film spectrophotometer (product name “instant multi-side optical system MCPD-2000”) manufactured by Otsuka Electronics Co., Ltd. When the thickness was 10 μm or more, the thickness was measured using a digital micrometer (“KC-351C type”) manufactured by Anritsu Corporation.
(3) Measurement of adhesive viscosity:
The viscosity was measured using a rheometer (manufactured by HAAKE, RSI-HS).
(4) Average particle size of colloid Measurement of average particle size:
The average particle size of the colloid was measured using a particle size distribution meter (Nikkiso Co., Ltd. Nanotrac UPA150).

(Production example of birefringent layer (A))
A modified polyvinyl alcohol-based resin (polymer represented by the formula (XI) in the same publication) described in Example 3 of [0103] to [0106] of JP-A No. 2007-161993 was prepared. This resin was dissolved in dichloromethane, and this solution was cast on a polyethylene terephthalate film substrate (thickness 70 μm) and dried to form a 110 μm thick resin film. After peeling this resin film from the base material, it was stretched free end in the width direction at 140 ° C. twice. This stretched resin film was used as the birefringent layer (A). The thickness of the birefringent layer (A) (stretched resin film) was 50 μm. The refractive index ellipsoid of the birefringent layer (A) was nx> ny = nz (Nz = 1.00), and Re (590) of the birefringent layer (A) was 140 nm.
Furthermore, Re (480) of the birefringent layer (A) was 132 nm, and Re (680) was 142 nm. Therefore, the birefringent layer (A) satisfied the relationship of Re (480) <Re (590) <Re (680).

(Production example of birefringent layer (B))
A resin film having a thickness of 110 μm was formed on the substrate in the same manner as in the production example of the birefringent layer (A). The resin film was peeled from the substrate, and then fixed-end stretched in the width direction at 140 ° C. twice. This stretched resin film was used as the birefringent layer (B). The thickness of the birefringent layer (B) (stretched resin film) was 50 μm. Further, the refractive index ellipsoid of the birefringent layer (B) was nx>ny> nz (Nz = 1.10), and Re (590) of the birefringent layer (B) was 140 nm.
Furthermore, Re (480) of the birefringent layer (B) was 132 nm, and Re (680) was 142 nm. Therefore, the birefringent layer (B) satisfied the relationship of Re (480) <Re (590) <Re (680).

(Production example of birefringent layer (C))
A cellulose-based film (thickness 80 μm, acetyl substitution degree = 0.04, propionyl substitution degree = 2.76) described in JP-A No. 2003-315538 is 1.6 times free end at 140 ° C. using a stretching machine. Stretched. This stretched cellulose film was used as the birefringent layer (C). The thickness of the birefringent layer (C) (cellulosic film after stretching) was 50 μm. The refractive index ellipsoid of the birefringent layer (C) was nx>ny> nz (Nz = 1.08), and Re (590) of the birefringent layer (C) was 88 nm.
Furthermore, Re (480) of the birefringent layer (C) was 83 nm, and Re (680) was 90 nm. Therefore, the birefringent layer (C) satisfied the relationship of Re (480) <Re (590) <Re (680).

(Example of production of polarizer (A))
A film (made by Kuraray Co., Ltd., trade name “VF-PS # 7500”) containing a polyvinyl alcohol resin having a thickness of 75 μm as a main component is placed in 5 baths under the conditions [1] to [5] below in the longitudinal direction of the film. The film was dipped while applying tension, and stretched so that the final stretching ratio was 6.2 times the original film length. The stretched film after the water washing treatment of [5] below was dried in an air circulation oven at 40 ° C. for 1 minute. The obtained stretched film was used as a polarizer (A).
[1] Swelling bath: 30 ° C. pure water.
[2] Dye bath: An aqueous solution at 30 ° C. containing 0.032 parts by mass of iodine with respect to 100 parts by mass of water and 0.2 parts by mass of potassium iodide with respect to 100 parts by mass of water.
[3] First cross-linking bath: 40 ° C. aqueous solution containing 3% by mass of potassium iodide and 3% by mass of boric acid.
[4] Second crosslinking bath: 60 ° C. aqueous solution containing 5% by mass of potassium iodide and 4% by mass of boric acid.
[5] Washing bath: 25 ° C. aqueous solution containing 3% by mass of potassium iodide.

(Example of production of transparent protective film (A))
(A) Production of (meth) acrylic resin Methyl methacrylate: 20 parts by mass, acrylamide: 80 parts by mass, potassium persulfate: 0.3 parts by mass, and ion-exchanged water: 1500 parts by mass were charged into the reactor. While replacing the inside of the reactor with nitrogen gas, the reaction was allowed to proceed at 70 ° C. until the monomer was completely converted into a polymer. This gave a suspension. Suspension: 0.05 parts by mass and ion-exchanged water: 165 parts by mass are supplied to a stainless steel autoclave equipped with a 5-liter capacity baffle and a fiddle-type stirring blade, and the reaction system is replaced with nitrogen gas. The mixture was stirred at 400 rpm. Next, a mixture of methacrylic acid: 27 parts by mass, methyl methacrylate: 73 parts by mass, t-dodecyl mercaptan: 0.4 parts by mass, and 2,2′-azobisisobutyronitrile: 0.2 parts by mass. And added to the reaction system with stirring.

After the addition of the above mixture, the temperature was raised to 70 ° C., and the time when the internal temperature reached 70 ° C. was regarded as the polymerization start time, which was maintained for 180 minutes to allow the polymerization to proceed. Thereafter, the reaction system was cooled, the polymer was separated, washed and dried in accordance with a normal method to obtain a bead-shaped copolymer. The degree of polymerization of this copolymer was 98%, and the mass average molecular weight was 130,000.
The obtained copolymer was subjected to an intramolecular cyclization reaction under the following conditions using a twin-screw extruder “TEX30” (L / D = 44.5) manufactured by Nippon Steel Co., Ltd. A (meth) acrylic resin was obtained. The intramolecular cyclization reaction was performed under the conditions of a screw rotation speed of 100 rpm, a raw material supply rate of 5 kg / hour, and a cylinder temperature of 290 ° C. while purging nitrogen from the hopper of the twin screw extruder at an amount of 10 L / min.
The obtained (meth) acrylic resin had a glutaric anhydride unit of 30 mol%, a methyl methacrylate unit of 69 mol%, and a methacrylic acid unit of 1 mol%. The glass transition temperature of the (meth) acrylic resin was 128 ° C.

(B) Production of acrylic elastic particles The following materials were added as an initial adjustment solution in a glass container (capacity 5 liters) with a cooler.
Deionized water: 120 parts by mass.
Potassium carbonate: 0.5 part by mass.
Dioctyl sulfosuccinate: 0.5 part by mass.
Potassium persulfate: 0.005 parts by mass.

While stirring the initial adjustment solution under a nitrogen atmosphere, a mixture of butyl acrylate: 53 parts by mass, styrene: 17 parts by mass, and allyl methacrylate (crosslinking agent): 1 part by mass was added, and the mixture was added at 70 ° C. for 30 minutes. It was made to react for minutes and the rubber-like polymer was obtained.
While continuing stirring, a mixture of methyl methacrylate: 21 parts by mass, methacrylic acid: 9 parts by mass, and potassium persulfate: 0.005 parts by mass was continuously added at 70 ° C. for 90 minutes. After completion of the addition, the shell layer was formed by holding for another 90 minutes.
The polymer latex was coagulated with sulfuric acid, neutralized with caustic soda, washed, filtered and dried to obtain core-shell type acrylic elastic particles. The average particle size of the rubbery polymer portion of the acrylic elastic particles was 140 nm. The average particle size was measured with an electron microscope. Moreover, the refractive index difference between the acrylic elastic particles and the (meth) acrylic resin was 0.002.

(C) Manufacture of (meth) acrylic resin-containing composition The (meth) acrylic resin: 80 parts by mass, the core-shell acrylic elastic particles: 20 parts by mass, and NaOCH ₃ : 0.2 parts by mass are blended. Using a twin-screw extruder “TEX30” (L / D = 44.5) manufactured by Nippon Steel Co., Ltd., an intramolecular cyclization reaction is performed under the following conditions to form a pellet-shaped (meth) acrylic resin-containing composition Got. The intramolecular cyclization reaction was performed under the conditions of a screw rotation speed of 100 rpm, a raw material supply rate of 5 kg / hour, and a cylinder temperature of 290 ° C. while purging nitrogen from the hopper of the twin screw extruder at an amount of 10 L / min.
The obtained (meth) acrylic resin-containing composition contained 30 mol% of glutaric anhydride units, 69 mol% of methyl methacrylate units, and 1 mol% of methacrylic acid units.

(D) Production of transparent protective film The above (meth) acrylic resin-containing composition: 50 parts by mass is added to 2-butanone: 150 parts by mass, and a double helical ribbon stirring blade is used. Stirring was performed for a time to obtain a solution having a resin concentration of 25% by mass. Next, this solution was subjected to pressure filtration with a sintered metal filter having a filtration accuracy of 1 μm to obtain a film forming stock solution.
Using a bar coater, the film-forming stock solution is uniformly applied to a glass plate (thickness 1.5 mm) on a substrate (PET film having a thickness of 100 μm) fixed with double-sided tape so that the film thickness after drying becomes 80 μm. Coated. Next, it dried on the following drying conditions using the hot air oven.
Initial drying: 50 ° C./10 minutes.
Secondary drying: 80 ° C./10 minutes.
Tertiary drying: 120 ° C./20 minutes.
Fourth drying: 140 ° C./20 minutes.
Final drying: 170 ° C./40 minutes.

  The film after the final drying was peeled from the substrate to obtain a (meth) acrylic resin film. This (meth) acrylic resin film was used as the transparent protective film (A). Re (590) of this transparent protective film (A) was 0 nm, and Rth (590) was 0 nm. Therefore, the transparent protective film (A) is a film having extremely excellent isotropic properties.

(Production example of adhesive (A))
Polyvinyl alcohol resin having an acetoacetyl group (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “Gosefimer Z200”. Average polymerization degree: 1200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 Mol%): 100 parts by mass and methylol melamine: 50 parts by mass were dissolved in pure water under a temperature condition of 30 ° C. to obtain an aqueous solution having a solid content concentration of 3.7% by mass.
To this aqueous solution: 100 parts by mass, an alumina colloid aqueous solution (average particle size 15 nm, solid content concentration 10%, positive charge): 18 parts by mass was added. The obtained solution (polyvinyl alcohol adhesive containing a metal compound colloid) was used as the adhesive (A). The adhesive (A) had a viscosity of 9.6 mPa · s and a pH of 4 to 4.5.

(Example of production of adhesive (B))
Polyvinyl alcohol resin having an acetoacetyl group (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., trade name “Gosefimer Z200”. Average polymerization degree: 1200, saponification degree: 98.5 mol%, acetoacetylation degree: 5 Mol%): 100 parts by mass and methylol melamine: 50 parts by mass were dissolved in pure water under a temperature condition of 30 ° C. to obtain an aqueous solution having a solid content concentration of 3.7% by mass.
The obtained aqueous solution (polyvinyl alcohol-based adhesive) was used as the adhesive (B).

[Example 1]
In order from the top, the transparent protective film (A), the first adhesive layer (dry thickness 0.3 μm) coated with the adhesive (A), the polarizer (A), and the adhesive (A). The polarizing plate of Example 1 was produced by laminating the applied second adhesive layer (dry thickness 0.3 μm) and the birefringent layer (A) (layer configuration as shown in FIG. 1).
Table 1 shows the layer structure of each polarizing plate of Examples and Comparative Examples.

[Example 2]
A polarizing plate of Example 2 was produced in the same manner as in Example 1 except that the birefringent layer (B) was used instead of the birefringent layer (A).

[Example 3]
A polarizing plate of Example 3 was produced in the same manner as in Example 1 except that the birefringent layer (C) was used in place of the birefringent layer (A).

[Example 4]
The polarizing plate of Example 4 except that the adhesive (B) was used as the adhesive of the second adhesive layer instead of the adhesive (A) of the second adhesive layer. Was made.

[Example 5]
The polarizing plate of Example 5 except that the adhesive (B) was used as the adhesive for the second adhesive layer instead of the adhesive (A) for the second adhesive layer. Was made.

[Example 6]
The polarizing plate of Example 6 except that the adhesive (B) was used as the adhesive for the second adhesive layer instead of the adhesive (A) for the second adhesive layer. Was made.

[Comparative Example 1]
In order from the top, the transparent protective film (A), the first adhesive layer (dry thickness 0.3 μm) coated with the adhesive (B), the polarizer (A), and the adhesive (B). A polarizing plate of Example 1 was produced by laminating the applied second adhesive layer (dry thickness 0.3 μm) and the birefringent layer (A).

[Comparative Example 2]
A polarizing plate of Comparative Example 2 was produced in the same manner as Comparative Example 1 except that the birefringent layer (B) was used instead of the birefringent layer (A).

[Comparative Example 3]
A polarizing plate of Comparative Example 3 was produced in the same manner as Comparative Example 1 except that the birefringent layer (C) was used instead of the birefringent layer (A).

[Evaluation]
The liquid crystal panel was taken out from a commercially available liquid crystal television (manufactured by BanQ, 32-inch liquid crystal television, trade name “DV3250”). The liquid crystal cell was taken out from the liquid crystal panel by neatly removing the optical members arranged on the viewing side and the non-viewing side of the liquid crystal panel.

  A commercially available polarizing plate (manufactured by Nitto Denko Corporation, trade name “NIBCOM-NXP”) was pasted on the opposite viewing side (backlight side) of the liquid crystal cell via an acrylic adhesive having a thickness of 12 μm. The commercially available polarizing plate is composed of a triacetyl cellulose film having a thickness of 80 μm, a polarizer, a triacetyl cellulose film having a thickness of 80 μm, and a polyimide resin film having a thickness of 4 μm (Re (590) = 55 nm, Rth (590) = 240 nm).

The polarizing plates of Examples 1 to 6 and Comparative Examples 1 to 3 were bonded to the viewing side of the liquid crystal cell via an acrylic pressure-sensitive adhesive having a thickness of 12 μm to prepare test liquid crystal panels.
Each test liquid crystal panel was displayed in black after 30 minutes had passed since the backlight was lit in a dark room at 23 ° C. The black display screen was visually observed, and the number of spots (knics) through which light was lost in the range of 500 mm × 500 mm at the center of the screen was counted. The results are also shown in Table 1.
As is clear from Table 1, the polarizing plates of Examples 1 to 6 have no nicks. On the other hand, the polarizing plates of Comparative Examples 1 to 3 are problematic in practical use because there are many occurrences of nicks. Therefore, the polarizing plate (polarizing plate of Examples 1-6) with which the polarizer and the transparent protective film are adhere | attached with the polyvinyl alcohol-type adhesive agent containing the metal compound colloid can suppress generation | occurrence | production of a nick. On the other hand, the polarizing plate (polarizing plate of Comparative Examples 1 to 3) in which the polarizer and the transparent protective film are bonded with a polyvinyl alcohol-based adhesive that does not contain a metal compound colloid frequently generates nicks.

It is a schematic cross section which shows an example of a structure of the polarizing plate of this invention. It is a schematic cross section which shows an example of a structure of the liquid crystal panel of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Polarizing plate 2 Transparent protective film 3 Polarizer 4 Birefringent layer 5 First adhesive layer 6 Second adhesive layer 9 Liquid crystal cell 11 First polarizing plate 12 Second polarizing plate

Claims (9)

In the polarizing plate in which the transparent protective film, the polarizer, and the birefringent layer are laminated in this order,
The transparent protective film includes a (meth) acrylic resin having a glutaric anhydride structure,
The polarizing plate, wherein the transparent protective film and the polarizer are bonded together using a polyvinyl alcohol-based adhesive containing a metal compound colloid.   The polarizing plate according to claim 1, wherein the birefringent layer has optical characteristics such that a retardation value increases as a wavelength increases. The (meth) acrylic resin having the glutaric anhydride structure comprises a glutaric anhydride unit represented by the following general formula (1) and an unsaturated carboxylic acid alkyl ester unit represented by the general formula (2). The polarizing plate according to claim 1 or 2.

However, in said general formula (1), R < ¹ > and R < ² > represents a hydrogen atom or a substituted or unsubstituted C1-C5 alkyl group each independently.

However, in the general formula (2), R ³ represents a hydrogen atom, or a substituted or unsubstituted alkyl group having 1 to 5 carbon atoms. R ⁴ represents a substituted or unsubstituted aliphatic hydrocarbon group having 1 to 5 carbon atoms, or a substituted or unsubstituted alicyclic hydrocarbon group having 1 to 5 carbon atoms.   The polarizing plate according to claim 1, wherein the metal compound colloid has an average particle diameter of 1 nm to 100 nm.   The polarizing plate according to claim 1, wherein the polyvinyl alcohol adhesive contains 200 parts by mass or less of the metal compound colloid with respect to 100 parts by mass of the polyvinyl alcohol resin.   The polarizing plate according to claim 1, wherein the metal compound colloid is an alumina colloid.   The polarizing plate according to claim 1, wherein the polyvinyl alcohol-based adhesive further contains a crosslinking agent.   The in-plane retardation value (Re (590)) at a wavelength of 590 nm of the transparent protective film is 0 nm to 10 nm, and the thickness direction retardation value (Rth (590)) at a wavelength of 590 nm is −10 nm to 10 nm. The polarizing plate according to any one of claims 1 to 7.   A liquid crystal display device comprising the polarizing plate according to claim 1.

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