JP2010102311A - Composite polarizing plate and liquid crystal display device using the same - Google Patents

Abstract

Disclosed is a polarizing plate, a composite polarizing plate thin and light phase difference film is laminated to satisfy the relation of comprising an olefin-based resin film _{n x> n z> n y} , the polarizing plate and the retardation film A composite polarizing plate having excellent adhesion strength and durability, and a liquid crystal display device using the same are provided.
A first protective layer and a second protective layer comprising a polarizing film, a cured product of a curable resin composition containing an epoxy compound laminated on both sides of the polarizing film, and a first protective layer. An adhesive layer 105 made of an adhesive having a storage elastic modulus of 0.1 MPa or more at 80 ° C. laminated on one protective layer 106, and an in-plane retardation of 100 to 300 nm laminated on the adhesive layer 105. And a retardation film 103 made of an olefin resin film having an Nz coefficient of 0.1 to 0.7, and a liquid crystal display device using the same.
[Selection] Figure 1

Description

  The present invention relates to a composite polarizing plate in which a retardation film is laminated on a polarizing plate. The present invention also relates to a liquid crystal display device using the composite polarizing plate.

  Liquid crystal display devices are used in various display devices by taking advantage of low power consumption, low voltage operation, light weight and thinness. The liquid crystal display device is composed of many optical members such as a liquid crystal cell, a polarizing plate, a retardation film, a light collecting sheet, a diffusion film, a light guide plate, and a light reflecting sheet. Therefore, it is possible to improve the production efficiency and lightness of the liquid crystal display device and to reduce the weight and thickness by improving the number of films or sheets constituting the optical member and the reduction of the film thickness. Such research is actively conducted.

  As a means for reducing the number of constituent films and sheets and reducing the thickness of a liquid crystal display device, a technique is known in which a protective film on one side of a polarizing plate is also used as a retardation film. For example, Patent Document 1 describes that, in a polarizing plate in which protective films are laminated on both surfaces of a polarizing film, at least one of the protective films is composed of a thermoplastic norbornene resin having a retardation film function. Yes. Patent Document 2 describes that at least one of the transparent protective layers of the polarizing film comprises a birefringent film (retardation film).

  One of the functions required for the retardation film is to optically compensate for the retardation due to the birefringence of the liquid crystal cell equally in the front direction and the oblique direction. Therefore, in the retardation film, the angle dependency of the retardation value is a very important optical characteristic.

Various retardation films having a substantially constant retardation value regardless of the angle have been proposed. For example, Patent Document 3 discloses that the intrinsic birefringence is positive and the molecules are oriented in the normal direction of the film surface. It is disclosed that a retardation film in which the retardation at normal incidence and the retardation at incidence from a direction inclined by 40 ° from the normal line are approximately the same is obtained by stretching the film. The retardation film has an in-plane slow axis direction, a refractive index in the in-plane fast axis direction and the thickness direction respectively n _x, when the n _y and n _z, a relationship n _x> n _z> n _y Show.

As a method for producing a retardation film which satisfies a relation of the _{n x> n z> n y} , in Patent Document 4, one side or by bonding a shrinkable film to both surfaces to form a laminate of the resin film, laminate A method of subjecting the material to heat stretching is disclosed. This method shrinks the resin film in the direction perpendicular to the stretching axis at the same time as stretching, causing orientation in the thickness direction (Z direction), and the refractive index distribution of the resin film changes greatly before and after stretching. I am letting. For this reason, the resin film used in this production method is preferably one that easily causes a phase difference at a low draw ratio. Conventionally, for example, a fragrance such as a polycarbonate resin film, a polyarylate resin film, or a polysulfone resin film is used. Family resin films have been used.

  Patent Document 5 discloses a film having heat shrinkability on at least one surface of a uniaxially stretched thermoplastic resin film, and the direction of the heat shrinkage axis is orthogonal to the stretch axis direction of the uniaxially stretched thermoplastic resin film. It is disclosed that a retardation film is produced by pasting and heat shrinking. The retardation film thus obtained has molecules oriented in the thickness direction. This method is also oriented in the thickness direction by utilizing the shrinkage of the uniaxially stretched thermoplastic resin film accompanying the heat shrinkage of the heat shrinkable film, so that mainly the aromatic resin film that easily develops the phase difference. Has been applied.

  However, since the aromatic resin film has a large absolute value of the photoelastic coefficient, the phase difference is likely to change with respect to stress. Therefore, when a liquid crystal display device in which a retardation film made of an aromatic resin film is placed between a liquid crystal cell and a polarizing film is exposed to a high temperature, the retardation of the retardation film is caused by the contraction stress of the polarizing film. The value may deviate from the design value, or the unevenness of the retardation value may occur due to the unevenness of the stress generated by the heat of the backlight in the liquid crystal display device. .

  On the other hand, since aliphatic resin films such as cyclic olefin resin films have a small absolute value of the photoelastic coefficient, in recent years, there has been an increasing trend to apply them to retardation films. However, since an aliphatic resin film generally hardly exhibits a retardation, a desired retardation value can be obtained even at a high draw ratio as well as a low draw ratio like an aromatic resin film. It was difficult. In particular, it is difficult to align the film so that a predetermined retardation value is obtained in the thickness direction as well as in the stretching axis direction. To apply the aliphatic resin film to the methods described in Patent Document 4 and Patent Document 5 above. There was a limit.

Therefore, Patent Document 6, on one or both sides of the cyclic olefin based resin film, bonding a large shrinkable film width direction shrinkage-plane retardation value is 100 to 350 nm, and (n _x -n how coefficient expressed by _{z) / (n x -n y} ) (Nz coefficient) is heated stretched to a 0.1 to 0.9 have been proposed. Here, _nx , _ny and _nz have the meanings as defined above. According to this method, the expression was hardly cycloolefin resin film of the phase difference, also oriented in the thickness direction with the stretching axis direction, is possible to produce a retardation film which satisfies a relation of n _x> n _z> n _y it can.

JP-A-8-43812 Japanese Patent Laid-Open No. 9-325216 JP-A-2-160204 JP-A-5-157911 Japanese Unexamined Patent Publication No. 7-230007 JP 2006-72309 A

However, olefin if the retardation film satisfying the relation of n _x> n _z> n _y made of a resin film adhered to one surface of the polarizing film, a polyvinyl alcohol-based polarizing film and the cellulose acetate system including the cyclic olefin resin film It has become clear that the polyvinyl alcohol-based adhesives conventionally used for bonding with a protective film do not have sufficient adhesive strength and have problems with durability.

An object of the present invention, a polarizing plate, a composite polarizing plate thin and light phase difference film is laminated to satisfy the relation of comprising an olefin-based resin film _{n x> n z> n y} , and a polarizing plate An object of the present invention is to provide a composite polarizing plate having excellent adhesion strength with a retardation film and excellent durability. Another object of the present invention is to provide a liquid crystal display device that uses this composite polarizing plate and is excellent in durability and reliability against temperature and humidity fluctuations.

According to the present invention, a second protective layer made of a cured product of a curable resin composition containing an epoxy compound that is cured by irradiation with active energy rays or heating is laminated on the second protective layer. A first protective layer comprising a polarizing film, a cured product of a curable resin composition containing an epoxy compound which is laminated on the polarizing film and cured by irradiation with active energy rays or heating; An adhesive layer made of an adhesive having a storage elastic modulus of 0.1 MPa or more at a temperature of 80 ° C. laminated on the protective layer, and the light having a wavelength of 590 nm laminated on the adhesive layer is as follows. There is provided a composite polarizing plate comprising a retardation film composed of an olefin resin film satisfying the formulas (1) and (2).
_{100nm ≦ (n x -n y)} × d ≦ 300nm (1)
_{0.1 ≦ (n x -n z)} / (n x -n y) ≦ 0.7 (2)
Here, in the above formula (1) and (2), n _x, n _y and n _z-plane slow axis direction of each retardation film, the in-plane fast axis direction, and a refractive index in the thickness direction D represents the thickness of the retardation film.

In the composite polarizing plate of the present invention, the epoxy compound is preferably a compound having at least one epoxy group bonded to an alicyclic ring in the molecule. Further, the first protective layer and the second protective layer is less than or equal plane retardation R _e is 10nm with respect to light having a wavelength of 590 nm, it is preferable absolute value of the retardation R _th in the thickness direction is 25nm or less.

  The olefin resin film constituting the retardation film is preferably made of an olefin resin containing a structural unit derived from an alicyclic olefin. Moreover, it is preferable that the thickness of a phase difference film is 20-300 micrometers, and it is preferable that the thickness of an adhesive layer is 1-40 micrometers.

  Moreover, according to this invention, the liquid crystal display device by which the said composite polarizing plate is arrange | positioned at the single side | surface or both surfaces of a liquid crystal cell is provided. In the liquid crystal display device of the present invention, the composite polarizing plate is disposed such that the retardation film side faces the liquid crystal cell. As the liquid crystal cell, a liquid crystal cell in a horizontal electric field mode, that is, an IPS (In-Plane-Switching) cell is preferably used.

  The composite polarizing plate of the present invention is formed by laminating a retardation film made of an olefin resin film via a pressure-sensitive adhesive layer on a protective layer made of a cured product of a curable resin composition that the polarizing plate has. The composite polarizing plate of the present invention having such a configuration has achieved thinning and lightening due to thinning and lightening of the protective layer disposed on both surfaces of the polarizing film, and the polarizing plate and the retardation film are sufficiently high. Bonded with adhesive strength, showing excellent durability. The composite polarizing plate of the present invention having excellent durability causes poor appearance and deterioration of optical characteristics even when exposed to harsh environments such as environments with large changes in temperature and humidity. Hateful. Moreover, the liquid crystal display device using this composite polarizing plate is excellent in durability and reliability.

It is a cross-sectional schematic diagram which shows the example of the layer structure of the composite polarizing plate which concerns on this invention.

<Composite polarizing plate>
FIG. 1 is a schematic cross-sectional view showing an example of the layer structure of the composite polarizing plate according to the present invention. A composite polarizing plate 100 shown in FIG. 1 includes a polarizing plate 110 in which a second protective layer 102, a polarizing film 101, and a first protective layer 106 are laminated in this order, and a first protection of the polarizing plate 110. And a retardation film 103 laminated on the layer 106 via an adhesive layer 105. Hereinafter, each member which comprises a composite polarizing plate is demonstrated in detail.

(Polarizing film)
The polarizing film used in the present invention (the polarizing film 101 in FIG. 1) is not particularly limited, but is one in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin, more specifically, uniaxial. A stretched polyvinyl alcohol-based resin film having a dichroic dye adsorbed and oriented can be preferably used. As the dichroic dye, iodine or a dichroic organic dye is used.

  As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers with other monomers copolymerizable with vinyl acetate. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, and vinyl ethers.

  The degree of saponification of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol-based resin may be modified, for example, polyvinyl formal modified with aldehydes, polyvinyl acetal, polyvinyl butyral, and the like can be used. The degree of polymerization of the polyvinyl alcohol-based resin is usually about 1,000 to 10,000, and preferably about 1,500 to 10,000.

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming the polyvinyl alcohol-based resin into a film is not particularly limited, and a known method is employed. The film thickness of the polyvinyl alcohol-based raw film is not particularly limited, but is, for example, about 10 μm to 150 μm.

  The polarizing film is usually a humidity adjusting step for adjusting the moisture of the raw film made of the polyvinyl alcohol resin as described above, a step of uniaxially stretching the polyvinyl alcohol resin film, and the polyvinyl alcohol resin film with a dichroic dye. It is manufactured through a process of dyeing and adsorbing the dichroic dye, a process of treating the polyvinyl alcohol resin film on which the dichroic dye is adsorbed and oriented with an aqueous boric acid solution, and a step of washing with water after the treatment with the aqueous boric acid solution. The

  Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing, or may be performed after dyeing. When uniaxial stretching is performed after dyeing with a dichroic dye, the uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, you may uniaxially stretch in these several steps. In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Moreover, the dry-type extending | stretching which extends | stretches in air | atmosphere may be sufficient, and the wet extending | stretching which extends | stretches in the state swollen with the solvent may be sufficient. The draw ratio is usually about 3 to 8 times. The thickness of the polarizing film obtained by drying after washing with water can be, for example, about 5 to 50 μm.

(First protective layer and second protective layer)
A first protective layer and a second protective layer (first protective layer 106 and second protective layer 102 in FIG. 1) provided on both surfaces of the polarizing film. Is a cured product of a curable resin composition containing a curable compound that may be cured by irradiation with active energy rays or heating (hereinafter, sometimes simply referred to as “curable compound”). Consists of. A polarizing plate and a retardation film are formed by laminating a protective layer composed of a cured product of such a curable resin composition and a retardation film composed of an olefin-based resin film described later using a predetermined pressure-sensitive adhesive layer. A highly durable composite polarizing plate can be obtained. Moreover, the composite polarizing plate obtained can be reduced in thickness and weight by forming the protective layers on both sides of the polarizing plate from the curable resin composition. An active energy ray means an ultraviolet-ray, visible light, an electron beam, an X-ray etc., for example. The curable compound may be a cationic polymerizable curable compound or a radical polymerizable curable compound. Examples of the cationic polymerizable curable compound include a compound having at least one epoxy group in the molecule (hereinafter sometimes referred to as “epoxy compound”), and at least one oxetane ring in the molecule. And the like (hereinafter sometimes referred to as “oxetane compounds”). Examples of radically polymerizable curable compounds include (meth) acrylic compounds having at least one (meth) acryloyloxy group in the molecule (hereinafter simply referred to as “(meth) acrylic compounds”). Can be mentioned). Such a curable resin composition containing a curable compound is cured by irradiation with active energy rays or heating to give a protective layer excellent in transparency, mechanical strength, thermal stability, and the like. The curable resin composition for forming the first protective layer and the curable resin composition for forming the second protective layer may be the same or different compositions, From the viewpoint of production efficiency, it is preferable to use the same curable resin composition.

The absolute values of the in-plane retardation R _e and the thickness direction retardation R _th for light having a wavelength of 590 nm of the protective layer are preferably closer to zero. Specifically, the in-plane retardation R _e with respect to light having a wavelength of 590nm is preferably 10nm or less, and more preferably 5nm or less. The absolute value of the thickness direction retardation R _th for light having a wavelength of 590 nm is preferably 25 nm or less, and more preferably 10 nm or less. Incidentally, retardation R _th in-plane retardation R _e and the thickness direction can be obtained by the following equation. In measuring the retardation, a cured product film of a curable resin composition obtained by forming a cured product of a curable resin composition on a polyethylene terephthalate (PET) film and peeling the PET film is used as a measurement sample. Use.

_{R e = (n x '-n} y') × d 1 (1)
R _th = [(n _x '+ _ny ') / 2-n _z '] × d ₁ (2)
Here, n _x ': refractive index n _y in-plane slow axis direction of the protective layer': refractive index n _z in the in-plane fast axis direction of the protective layer (a direction perpendicular to the slow axis direction) ': Protection Refractive index in the thickness direction of the layer d ₁ : thickness of the protective layer.

By the retardation value R _th in-plane retardation R _e and the thickness direction of the protective layer in the above range, when the composite polarizing plate and the retardation film and the liquid crystal cell was pasted to the liquid crystal cell so as to face, Light leakage at the time of black display in the obtained liquid crystal display device can be effectively prevented.

  The curable resin composition for forming the protective layer is an epoxy compound (as defined above, an epoxy compound in the present invention is a curable compound that can be cured by irradiation with active energy rays or heating. It preferably contains a compound having at least one epoxy group in the molecule. Thereby, the protective layer which shows favorable adhesiveness with respect to a polarizing film and an adhesive layer can be obtained.

  As the epoxy compound, it is preferable to use, as a main component, an epoxy compound that does not contain an aromatic ring in the molecule from the viewpoints of weather resistance, refractive index, and cationic polymerizability. Examples of such epoxy compounds that do not contain an aromatic ring in the molecule include hydrogenated epoxy compounds, aliphatic epoxy compounds, alicyclic epoxy compounds, and the like.

  The hydrogenated epoxy compound is a compound in which the aromatic ring of the aromatic epoxy compound is selectively hydrogenated. Examples of the aromatic epoxy compound include bisphenol type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; phenol novolac epoxy resin, cresol novolac epoxy resin, And a novolak-type epoxy resin such as hydroxybenzaldehyde phenol novolac epoxy resin; a glycidyl ether of tetrahydroxydiphenylmethane, a glycidyl ether of tetrahydroxybenzophenone, and a polyfunctional epoxy resin such as epoxidized polyvinylphenol. An aromatic polyhydroxy compound (for example, bisphenol A) as a raw material for these aromatic epoxy compounds is subjected to a nuclear hydrogenation reaction under pressure in the presence of a catalyst, and the resulting hydrogenated polyhydroxy compound is subjected to epichlorohydrin. To obtain a hydrogenated epoxy compound as described above. Of these, hydrogenated bisphenol A glycidyl ether is preferably used as the hydrogenated epoxy compound.

  Examples of the aliphatic epoxy compound include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. More specifically, 1,4-butanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; glycerin triglycidyl ether; trimethylolpropane triglycidyl ether; polyethylene glycol diglycidyl ether; propylene Diglycidyl ethers of glycols; polyether polyols obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as ethylene glycol, propylene glycol, and glycerin Examples thereof include polyglycidyl ether.

  The alicyclic epoxy compound means an epoxy compound having at least one epoxy group bonded to the alicyclic ring. The “epoxy group bonded to the alicyclic ring” has a structure represented by the following formula, wherein m is an integer of 2 to 5.

Therefore, the alicyclic epoxy compound is a compound having at least one structure represented by the above formula in the molecule. More specifically, a compound in which one or a plurality of hydrogen groups in (CH ₂ ) _m in the above formula are bonded to another chemical structure can be an alicyclic epoxy compound. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group.

  Among the epoxy compounds as described above, alicyclic epoxy compounds, that is, compounds in which at least one of the epoxy groups is bonded to the alicyclic ring are preferable. = 3) or a compound having at least one oxabicycloheptane ring (m = 4 in the above formula), that is, an epoxy compound having at least one epoxy group bonded to a cyclopentane ring or a cyclohexane ring. The cured product has a high elastic modulus and is excellent in adhesiveness with a polarizing film, so that it is more preferably used. Although the structure of the alicyclic epoxy compound preferably used in the present invention is specifically exemplified below, it is not limited to these compounds.

  (A) Epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (I):

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(B) Epoxycyclohexanecarboxylates of alkanediol represented by the following formula (II):

(In the formula, R ³ and R ⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and n represents an integer of 2 to 20).
(C) Epoxycyclohexyl methyl esters of dicarboxylic acid represented by the following formula (III):

(In the formula, R ⁵ and R ⁶ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and p represents an integer of 2 to 20).
(D) Epoxycyclohexyl methyl ethers of polyethylene glycol represented by the following formula (IV):

(In the formula, R ⁷ and R ⁸ independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and q represents an integer of 2 to 10).
(E) Epoxycyclohexyl methyl ethers of alkanediols represented by the following formula (V):

(In the formula, R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and r represents an integer of 2 to 20).
(F) Diepoxy trispiro compound represented by the following formula (VI):

(In the formula, R ¹¹ and R ¹² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(G) Diepoxy monospiro compound represented by the following formula (VII):

(In the formula, R ¹³ and R ¹⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(H) Vinylcyclohexene diepoxides represented by the following formula (VIII):

(In the formula, R ¹⁵ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(I) Epoxycyclopentyl ethers represented by the following formula (IX):

(In the formula, R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
(J) Diepoxytricyclodecanes represented by the following formula (X):

(In the formula, R ¹⁸ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)
Among the alicyclic epoxy compounds exemplified above, the following alicyclic epoxy compounds are commercially available or similar, and are preferably used because they are relatively easy to obtain. .

(A) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (7-oxa-bicyclo [4.1.0] hept-3-yl) methanol [formula (I ) In which R ¹ = R ² = H],
(B) 4-methyl-7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (4-methyl-7-oxa-bicyclo [4.1.0] hept-3-yl) methanol Esterified product [compound of the above formula (I), R ¹ = 4-CH ₃ , R ² = 4-CH ₃ ],
(C) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and 1,2-ethanediol [in the above formula (II), R ³ = R ⁴ = H, n = 2 Compound of
(D) (7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in the above formula (III), R ⁵ = R ⁶ = H, p = 4 compound ],
(E) (4-Methyl-7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in the above formula (III), R ⁵ = 4-CH ₃ , R _{^{6 = 4-CH 3, p}} = 4 the compound]
(F) Etherified product of (7-oxabicyclo [4.1.0] hept-3-yl) methanol and 1,2-ethanediol [in the above formula (V), R ⁹ = R ¹⁰ = H, r = 2 compounds].

  In the present invention, the epoxy compound may be used alone or in combination of two or more.

  In the curable resin composition used for forming the protective layer, the epoxy compound is preferably contained in a proportion of 30 to 100% by weight in the curable compound, and contained in a proportion of 35 to 70% by weight. It is more preferable that it is contained in a proportion of 40 to 60% by weight. When the content of the epoxy compound is less than 30% by weight, the adhesion with the polarizing film may be lowered.

  The curable resin composition may contain an oxetane compound in addition to the epoxy compound. By adding an oxetane compound, the viscosity of the curable resin composition can be lowered and the curing rate can be increased.

  The oxetane-based compound is a compound having at least one oxetane ring, that is, a 4-membered ether structure in the molecule, such as 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl- 3-Oxetanyl) methoxymethyl] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) Oxetane, phenol novolac oxetane and the like can be mentioned. These oxetane compounds can be easily obtained as commercial products. For example, all of these oxetane compounds are trade names such as “Aron Oxetane OXT-101”, “Aron Oxetane OXT-121”, “Aron Oxetane OXT-211”. , “Aron Oxetane OXT-221”, “Aron Oxetane OXT-212” (both manufactured by Toagosei Co., Ltd.) and the like. Although the compounding quantity of an oxetane type compound is not restrict | limited in particular, Usually, it is 30 weight% or less in a sclerosing | hardenable compound, and 10-25 weight% is preferable.

  The curable resin composition used for forming the protective layer contains a cationically polymerizable epoxy compound, and optionally also contains a cationically polymerizable oxetane compound. Therefore, the curable resin composition includes photocationic polymerization. It is preferable that an initiator is blended. When a cationic photopolymerization initiator is used, a protective layer can be formed at room temperature, reducing the need to consider the heat resistance of the polarizing film or distortion due to expansion, and forming the protective layer on the polarizing film with good adhesion can do. Moreover, since a photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with a curable resin composition.

  Photocationic polymerization initiators generate cationic species or Lewis acids upon irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiate a polymerization reaction of an epoxy compound or an oxetane compound. It is. In the present invention, any type of cationic photopolymerization initiator may be used, but it is preferable from the viewpoint of workability that the potential is imparted. The photocationic polymerization initiator is not particularly limited, and examples thereof include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; and iron-allene complexes. .

  Examples of the aromatic diazonium salt include benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.

  Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, and di (4-nonylphenyl) iodonium hexafluorophosphate.

  Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis [diphenylsulfonio] diphenyl sulfide bishexa. Fluorophosphate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluoroantimonate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bis Hexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-tolui) ) Sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4′-diphenylsulfonio-diphenyl sulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4′-diphenyl Examples include sulfonio-diphenyl sulfide hexafluoroantimonate, and 4- (p-tert-butylphenylcarbonyl) -4′-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate.

  Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, and xylene-cyclopentadienyl iron (II ) -Tris (trifluoromethylsulfonyl) methanide and the like.

  These photocationic polymerization initiators can be easily obtained as commercial products. For example, “Kayarad PCI-220” and “Kayarad PCI-620” (Nippon Kayaku Co., Ltd. )), “UVI-6990” (manufactured by Union Carbide), “Adekaoptomer SP-150”, “Adekaoptomer SP-170” (manufactured by ADEKA, Inc.), “CI-5102”, “ "CIT-1370", "CIT-1682", "CIP-1866S", "CIP-2048S", "CIP-2064S" (Nippon Soda Co., Ltd.), "DPI-101", "DPI-102" , “DPI-103”, “DPI-105”, “MPI-103”, “MPI-105”, “BBI-101”, “BBI-102”, “BBI” 103 "," BBI-105 "," TPS-101 "," TPS-102 "," TPS-103 "," TPS-105 "," MDS-103 "," MDS-105 "," DTS-102 " “DTS-103” (manufactured by Midori Chemical Co., Ltd.), “PI-2074” (manufactured by Rhodia), and the like.

  These cationic photopolymerization initiators may be used alone or in combination of two or more. Among them, in particular, the aromatic sulfonium salt has an ultraviolet absorption property even in a wavelength region of 300 nm or more, so that it can provide a cured product having excellent curability and good mechanical strength and good adhesion to a polarizing film. Since it can be used, it is preferably used.

  The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of total amounts of cation polymerizable curable compounds, such as an epoxy-type compound and an oxetane type compound, 6 parts by weight is preferred. When the blending amount of the cationic photopolymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the total amount of the cationic polymerizable curable compound, the curing becomes insufficient, and the mechanical strength, the protective layer and the polarization are reduced. There exists a tendency for adhesiveness with a film to fall. On the other hand, if the amount of the cationic photopolymerization initiator exceeds 20 parts by weight with respect to 100 parts by weight of the total amount of the cation polymerizable curable compound, the ionic substance in the cured product increases, resulting in a cured product. As a result, the hygroscopicity of the protective layer may increase, and the durability of the protective layer may decrease.

  Moreover, it is preferable that the curable resin composition used for formation of a protective layer contains the (meth) acrylic-type compound which is radically polymerizable with the said epoxy-type compound or an epoxy-type compound and an oxetane-type compound. By using the (meth) acrylic compound in combination, it is possible to obtain a protective layer having high hardness, excellent mechanical strength, and higher durability. Furthermore, adjustments such as the viscosity of the curable resin composition, the curing rate, the surface curability of the resulting protective layer, and the adhesion to the polarizing film can be more easily performed.

  The (meth) acrylic compound is obtained by reacting at least one (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule or two or more functional group-containing compounds. Examples include (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having one (meth) acryloyloxy group. These may be used alone or in combination of two or more. When using 2 or more types together, 2 or more types of (meth) acrylate monomers may be sufficient, 2 or more types of (meth) acrylate oligomers may be sufficient, and 1 or more types of (meth) acrylate monomers and ( One or more meth) acrylate oligomers may be used in combination.

  Examples of the (meth) acrylate monomer include a monofunctional (meth) acrylate monomer having one (meth) acryloyloxy group in the molecule, and a bifunctional (meth) having two (meth) acryloyloxy groups in the molecule. Examples thereof include acrylate monomers and polyfunctional (meth) acrylate monomers having 3 or more (meth) acryloyloxy groups in the molecule.

  Specific examples of monofunctional (meth) acrylate monomers include tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate 2-hydroxy-3-phenoxypropyl (meth) acrylate, isobutyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, Benzyl (meth) acrylate, isobornyl (meth) acrylate, phenoxyethyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate Include ethyl carbitol (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, and phenoxy polyethylene glycol (meth) acrylate.

  Moreover, a carboxyl group-containing (meth) acrylate monomer may be used as the monofunctional (meth) acrylate monomer. Examples of the carboxyl group-containing monofunctional (meth) acrylate monomer include 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, carboxyethyl (meth) acrylate, and 2- (meth). Examples include acryloyloxyethyl succinic acid, N- (meth) acryloyloxy-N ′, N′-dicarboxymethyl-p-phenylenediamine, and 4- (meth) acryloyloxyethyl trimellitic acid.

  Bifunctional (meth) acrylate monomers include alkylene glycol di (meth) acrylates, polyoxyalkylene glycol di (meth) acrylates, halogen-substituted alkylene glycol di (meth) acrylates, aliphatic polyol di (meth) acrylates Di (meth) acrylates of hydrogenated dicyclopentadiene or tricyclodecane dialkanol, di (meth) acrylates of dioxane glycol or dioxane dialkanol, di (meth) of alkylene oxide adducts of bisphenol A or bisphenol F Representative are acrylates and epoxy di (meth) acrylates of bisphenol A or bisphenol F, but are not limited to these, and various types can be used.

  More specific examples of the bifunctional (meth) acrylate monomer include ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1, 6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol di (meth) acrylate, ditrimethylol Propane di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene Glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, silicone di (meth) acrylate, hydroxypivalate ester neopentyl glycol di (meth) acrylate, 2,2-bis [4- (Meth) acryloyloxyethoxyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxyethoxyethoxycyclohexyl] propane, hydrogenated dicyclopentadienyl di (meth) acrylate, tricyclodecandi Methanol di (meth) acrylate, 1,3-dioxane-2,5-diyl di (meth) acrylate [also known as dioxane glycol di (meth) acrylate], hydroxypivalaldehyde and trimethylol group Acetal compound with bread [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane], and tris (hydroxy) And ethyl) isocyanurate di (meth) acrylate.

  The trifunctional or higher polyfunctional (meth) acrylate monomers include glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol. Tri- or higher functional aliphatic such as tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate Poly (meth) acrylates of polyols are typical ones. Besides, poly (meth) acrylates of tri- or higher functional halogen-substituted polyols, alkylene of glycerol Tri (meth) acrylates of xoxide adducts, tri (meth) acrylates of trimethylolpropane alkylene oxide adducts, 1,1,1-tris [(meth) acryloyloxyethoxyethoxy] propane, tris (hydroxyethyl) isocyanurate Examples include tri (meth) acrylates and silicone hexa (meth) acrylate.

  Examples of (meth) acrylate oligomers include urethane (meth) acrylate oligomers, polyester (meth) acrylate oligomers, and epoxy (meth) acrylate oligomers.

  The urethane (meth) acrylate oligomer is a compound having a urethane bond (—NHCOO—) and at least two (meth) acryloyloxy groups in the molecule. Specifically, a urethanization reaction product of a hydroxyl group-containing (meth) acrylate monomer having at least one (meth) acryloyloxy group and at least one hydroxyl group in the molecule, and a polyisocyanate, and polyols Urethane reaction product of terminal isocyanate group-containing urethane compound obtained by reaction with polyisocyanate and (meth) acrylate monomer each having at least one (meth) acryloyloxy group and at least one hydroxyl group in the molecule Etc.

  Examples of the hydroxyl group-containing (meth) acrylate monomer used in the urethanization reaction include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 2-hydroxy-3- Examples include phenoxypropyl (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol penta (meth) acrylate.

  Examples of the polyisocyanate used for the urethanization reaction with such a hydroxyl group-containing (meth) acrylate monomer include hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and among these diisocyanates. Diisocyanates obtained by hydrogenating aromatic isocyanates (for example, hydrogenated tolylene diisocyanate and hydrogenated xylylene diisocyanate), di- or tri-isocyanates such as triphenylmethane triisocyanate, dibenzylbenzene triisocyanate, And polyisocyanates obtained by multiplying the above diisocyanates.

  In addition to aromatic, aliphatic, and alicyclic polyols, polyester polyols, polyether polyols, and the like are used as polyols used to obtain terminal isocyanate group-containing urethane compounds by reaction with polyisocyanates. Can do. Aliphatic and alicyclic polyols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylol ethane, trimethylol propane, ditriol. Examples include methylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

  The polyester polyol is obtained by a dehydration condensation reaction between the above polyols and a polybasic carboxylic acid or an anhydride thereof. Polybasic carboxylic acids or their anhydrides include (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, (anhydrous) Examples include phthalic acid, isophthalic acid, terephthalic acid, and hexahydro (anhydride) phthalic acid.

  Examples of the polyether polyol include polyalkylene glycol, polyoxyalkylene-modified polyol obtained by reaction of the above polyols or dihydroxybenzenes with alkylene oxide, and the like.

  The polyester (meth) acrylate oligomer is a compound having an ester bond and at least two (meth) acryloyloxy groups in the molecule. Specifically, it can be obtained by dehydration condensation reaction of (meth) acrylic acid, polybasic carboxylic acid or anhydride thereof, and polyol. Polybasic carboxylic acids or anhydrides used in the dehydration condensation reaction include (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyrone Examples include merit acid, hexahydro (anhydride) phthalic acid, (anhydrous) phthalic acid, isophthalic acid, and terephthalic acid. Examples of the polyol used for the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, trimethylolpropane, Examples include ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

  The epoxy (meth) acrylate oligomer can be obtained by addition reaction of polyglycidyl ether and (meth) acrylic acid, and has at least two (meth) acryloyloxy groups in the molecule. Examples of the polyglycidyl ether used in the addition reaction include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and bisphenol A diglycidyl ether. It is done.

  Among the above (meth) acrylate compounds, a compound having a structure represented by the following formula (XI) or (XII) gives a high elastic modulus to the cured product, and is also a cationically polymerizable curable compound, particularly an alicyclic ring. When combined with an epoxy compound, a protective layer having excellent adhesion to the polarizing film is obtained, which is preferable.

(Wherein, Q ₁ and Q ₂ independently of one another are (meth) acrylate represents an acryloyloxy group or a (meth) acryloyloxy group, wherein the carbon number of alkyl is 1 to 10, Q ₃ is hydrogen or Represents a hydrocarbon group having 1 to 10 carbon atoms.)
In the above formula (XI) or (XII), when Q ₁ or Q ₂ is a (meth) acryloyloxyalkyl group, the alkyl may be linear or branched and has 1 to 10 carbon atoms. Generally, about 1 to 6 carbon atoms are sufficient. In the formula (XII), when Q ₃ is a hydrocarbon group, it may be linear or branched, and can typically be an alkyl group. In this case, it is generally sufficient for the alkyl group to have about 1 to 6 carbon atoms.

The compound represented by the formula (XI) is a di (meth) acrylate derivative of hydrogenated dicyclopentadiene or tricyclodecane dialkanol, and specific examples thereof are those exemplified above. Cyclopentadienyl di (meth) acrylate [in formula (XI), Q ₁ = Q ₂ = (meth) acryloyloxy group compound], and tricyclodecane dimethanol di (meth) acrylate [in formula (XI) Q ₁ = Q ₂ = (Meth) acryloyloxymethyl group compound] and the like.

Further, the compound represented by the formula (XII) is a di (meth) acrylate derivative of dioxane glycol or dioxane dialkanol, and specific examples thereof include those exemplified above, but 1,3-dioxane- 2,5-diyldi (meth) acrylate [also known as dioxane glycol di (meth) acrylate, compound of formula (XII), Q ₁ = Q ₂ = (meth) acryloyloxy group, Q ₃ = H], and hydroxypi Di (meth) acrylate of acetal compound [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane] of valaldehyde and trimethylolpropane [in the formula (XII), Q ₁ = (meth) acryloyloxy methyl group, Q ₂ = 2- (meth) acrylate Roiruokishi 1,1-dimethylethyl group, the compound of Q ₃ = ethyl group], and the like.

  In the curable resin composition used for forming the protective layer, the content of the (meth) acrylic compound is preferably 70% by weight or less, more preferably 35 to 70% by weight, and more preferably 40 to 60% by weight in the curable compound. % Is more preferable. If the content of the (meth) acrylic compound exceeds 70% by weight, the adhesion with the polarizing film may be lowered.

  When the curable resin composition contains the (meth) acrylic compound as described above, a radical photopolymerization initiator is preferably blended in the curable resin composition. Any radical photopolymerization initiator may be used as long as it can initiate polymerization of a radical polymerizable curable compound such as a (meth) acrylic compound by irradiation with active energy rays. it can. Specific examples of the radical photopolymerization initiator include, for example, acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl- Acetophenone-based initiators such as 1- [4- (methylthio) phenyl-2-morpholinopropan-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone, 4-chlorobenzophenone, And benzophenone initiators such as 4,4′-diaminobenzophenone; benzoin ether initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone initiators such as 4-isopropylthioxanthone; and others, xanthone, fluorenone, camphor Non, benzaldehyde, and anthraquinone, and the like.

  The compounding quantity of radical photopolymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of (meth) acrylic-type compounds, and 1-6 weight part is preferable. When the blending amount of the radical photopolymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the (meth) acrylic compound, curing becomes insufficient, and the mechanical strength of the protective layer and the protective layer and the polarizing film In some cases, the adhesion of the resin may deteriorate. Moreover, when the compounding quantity of radical photopolymerization initiator exceeds 20 weight part with respect to 100 weight part of (meth) acrylic-type compounds, the curable compound (cation polymerizable property containing an epoxy-type compound in a curable resin composition). The amount of the curable compound and the radical polymerizable acrylic compound) may be relatively small, and the durability performance required as the protective layer may not always be sufficient.

  The curable resin composition can further contain a photosensitizer as necessary. By using a photosensitizer, the reactivity of cationic polymerization or radical polymerization can be improved, and the mechanical strength of the protective layer and the adhesion between the protective layer and the polarizing film can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes. Specific photosensitizers include, for example, benzoin methyl ether, benzoin isopropyl ether, and benzoin derivatives such as α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, o-benzoylbenzoate Benzophenone derivatives such as methyl acid, 4,4′-bis (dimethylamino) benzophenone, and 4,4′-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; Anthraquinone derivatives such as anthraquinone and 2-methylanthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; other, α, α-diethoxyacetophenone, Njiru, fluorenone, xanthone, uranyl compounds, and halogen compounds and the like. These may be used alone or in combination. The photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight with respect to 100 parts by weight of the curable compound.

  Moreover, the curable resin composition may contain an antistatic agent for imparting antistatic performance to the polarizing plate. The antistatic agent is not particularly limited, and a known antistatic agent can be used. For example, cationic surfactants such as acyloylamidopropyldimethylhydroxyethylammonium nitrate, acyloylamidopropyltrimethylammonium sulfate, and cetylmorpholium methosulfate; linear alkyl phosphate potassium salt, polyoxyethylene alkyl Anionic surfactants such as potassium phosphate and alkane sulfonate; N, N-bis (hydroxyethyl) -N-alkylamine, its fatty acid ester derivatives, and polyhydric alcohol fatty acid partial esters Nonionic surfactants and the like. The blending ratio of the antistatic agent is appropriately determined according to desired characteristics, but is usually about 0.1 to 20 parts by weight with respect to 100 parts by weight of the curable compound.

  In the curable resin composition, a known polymer additive usually used for polymers can be added. For example, primary antioxidants such as phenols and amines, sulfur secondary antioxidants, hindered amine light stabilizers (HALS), benzophenone, benzotriazole, and benzoate UV absorbers, etc. Can be mentioned.

  Silica fine particles may be added to the curable resin composition. By adding silica fine particles, the hardness and mechanical strength of the protective layer obtained can be further improved. Silica fine particles can be blended in the curable resin composition as a liquid dispersed in an organic solvent, for example.

  The silica fine particles may have reactive functional groups such as hydroxyl groups, epoxy groups, (meth) acryloyl groups, and vinyl groups on the surface. The particle size of the silica fine particles is usually 100 nm or less, preferably about 5 to 50 nm. When the particle diameter of the fine particles exceeds 100 nm, the transparency of the protective layer may be lowered.

  When silica fine particles dispersed in an organic solvent are used, the silica concentration is not particularly limited, and commercially available products, for example, about 20 to 40% by weight can be used.

  Examples of silica fine particles dispersed in an organic solvent available as a commercial product include, for example, “methanol silica sol” (manufactured by Nissan Chemical Industries, Ltd., silica particle size of 10 to 15 nm, solid content of 30 wt. %), “MA-ST-M” (manufactured by Nissan Chemical Industries, Ltd., silica particle size 20 to 25 nm, solid content 40 wt%), and “OSCAL 1132” (manufactured by Catalyst Chemical Industries, Ltd., silica particle size) 10 to 20 nm, solid content 30 to 31% by weight); “OSCAL 1232” whose organic solvent is ethyl alcohol (manufactured by Catalyst Chemical Industry Co., Ltd., silica particle size 10 to 20 nm, solid content 30 to 31% by weight); organic “OSCAL 1332” (catalyst chemical industry Co., Ltd., silica particle size 10 to 20 nm, solid content 30 to 31 wt%); "IPA-ST" (manufactured by Nissan Chemical Industries, silica particle size 10-15 nm, solid content 30% by weight), and "OSCAL 1432" (catalyst chemical industry Co., Ltd., silica particles) "NBA-ST" in which the organic solvent is n-butyl alcohol (manufactured by Nissan Chemical Industries, silica particle size of 10 to 15 nm, solid content of 20% by weight) And “OSCAL 1532” (manufactured by Catalyst Kasei Kogyo Co., Ltd., silica particle size 10 to 20 nm, solid content 30 to 31 wt%); “EG-ST” (Nissan Chemical Industry Co., Ltd.) in which the organic solvent is ethylene glycol "OSCAL 1632" (catalyst chemical industry Co., Ltd., silica particle size 10 to 10%, organic solvent is ethyl cellosolve) 0 nm, solid content 30 to 31% by weight); “NPC-ST” whose organic solvent is ethylene glycol mono n-propyl ether (manufactured by Nissan Chemical Industries, Ltd., silica particle size 10 to 15 nm, solid content 30% by weight) "DMAC-ST" (manufactured by Nissan Chemical Industries, silica particle size 10-15 nm, solid content 20% by weight), and "DMAC-ST-ZL" (Nissan Chemical Industry Co., Ltd.) “XBA-ST” (manufactured by Nissan Chemical Industries, Ltd., silica particle diameter of 10 to 15 nm), wherein the organic solvent is a mixture of xylene and n-butyl alcohol. "MIBK-ST" (manufactured by Nissan Chemical Industries, Ltd., silica particle size 10 to 15 nm, solid content 30% by weight) ”;“ MEK-ST ”(manufactured by Nissan Chemical Industries, silica particle size 10-15 nm, solid content 30% by weight),“ SP-1120 ”(manufactured by Konishi Chemical Co., Ltd.) Silica particle size 15 to 20 nm, solid content 5 to 10 wt%), and “SP-6120” (manufactured by Konishi Chemical Industry Co., Ltd., silica particle size 15 to 20 nm, solid content 5 to 10 wt%). These 1 type (s) or 2 or more types can be used suitably. In addition, “Snowtex 20” (manufactured by Nissan Chemical Industries, Ltd., silica particle size 10 to 20 nm) and “Snowtex C” (manufactured by Nissan Chemical Industries, Ltd., silica particle size 10 to 10) whose dispersion medium is water are used. 20 nm) or the like can also be used.

  The amount of the silica fine particles added is preferably 5 to 250 parts by weight, more preferably 10 to 100 parts by weight with respect to 100 parts by weight of the curable compound contained in the curable resin composition. If the addition amount of the silica fine particles is less than 5 parts by weight based on 100 parts by weight of the curable compound, the hardness of the protective layer may not be sufficiently improved by the addition of the silica fine particles. On the other hand, when the addition amount of silica fine particles exceeds 250 parts by weight with respect to 100 parts by weight of the curable compound, the adhesion between the polarizing film and the protective layer is reduced, or the dispersion of silica fine particles in the curable resin composition is stable. May decrease, or the viscosity of the curable resin composition may increase excessively.

  Furthermore, the curable resin composition may contain a solvent as necessary. The solvent is appropriately selected depending on the solubility of the components constituting the curable resin composition. Commonly used solvents include aliphatic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, propanol, isopropanol, and n-butanol Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as methyl acetate, ethyl acetate, and butyl acetate; cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; methylene chloride and chloroform And halogenated hydrocarbons. The mixing ratio of the solvent is appropriately determined from the viewpoint of adjusting the viscosity depending on the processing purpose such as film forming property.

  In addition, when the curable resin composition is applied onto a polarizing film or a substrate, the coating property on the polarizing film or the substrate is poor, or the surface property of the cured product of the curable resin composition is poor. In order to improve them, a leveling agent can be added to the curable resin composition. As the leveling agent, various compounds such as silicone-based, fluorine-based, polyether-based, acrylic acid copolymer-based, and titanate-based compounds can be used. These leveling agents may be used alone or in combination of two or more.

  The amount of the leveling agent added is preferably 0.01 to 1 part by weight, more preferably 0.1 to 0.7 part by weight, based on 100 parts by weight of the curable compound contained in the curable resin composition. More preferably, it is 2 to 0.5 parts by weight. When the amount of the leveling agent added is less than 0.01 parts by weight with respect to 100 parts by weight of the curable compound, there are cases where the improvement of the coatability and the surface property is not sufficient. When the addition amount of a leveling agent exceeds 1 weight part with respect to 100 weight part of curable compounds, the adhesiveness of a polarizing film and a protective layer may fall.

  Further, the curable resin composition for forming the second protective layer used in the present invention may contain an antiglare material in order to give the polarizing plate an antiglare function. As the antiglare material, cross-linked acrylic resin beads are preferably used. Cross-linked acrylic resin beads include acrylic acid and its alkyl or aryl ester, methacrylic acid and its alkyl or aryl ester, acrylic monomers such as acrylamide and acrylonitrile, a polymerization initiator such as persulfuric acid, and ethylene glycol dimethacrylate, for example. It is a bead-like thing which consists of a crosslinked product of a polymer and a copolymer obtained by polymerizing by a suspension polymerization method using a crosslinking agent such as. Particularly preferred are those prepared using methyl methacrylate as the acrylic monomer. The cross-linked acrylic resin beads used in the present invention have a spherical or almost spherical shape and do not exhibit oil absorption. Therefore, when used for a roughened layer (a layer having an uneven surface), excellent contamination resistance Sex can be expressed. In addition, in order to improve the dispersibility in the curable resin composition, the crosslinked acrylic resin beads are subjected to a surface modification treatment with organic / inorganic materials such as fats and oils, silane coupling agents, metal oxides, and the like. Also good.

  The crosslinked acrylic resin beads used in the present invention have a particle size distribution in which particles having a particle size in the range of 0.5 to 6.0 μm are 60% by weight or more, and particles having a particle size of more than 6.0 μm are less than 20% by weight. preferable. In particular, particles having a particle size distribution in which particles having a particle diameter of 0.5 to 6.0 μm are 80% by weight or more and particles having a particle diameter of more than 6.0 μm are less than 10% by weight are preferable. The composite polarizing plate is applied to the liquid crystal display device when the particle size in the range of 0.5 to 6.0 μm is less than 60% by weight or the particle size larger than 6.0 μm is 20% by weight or more. When doing so, display glare may occur. Further, when the particle size in the range of 0.5 to 6.0 μm is less than 60% by weight and the particle size exceeding 6.0 μm is 20% by weight or more, glare occurs and the display The anti-glare property is deteriorated.

  In the present invention, the blending amount of the crosslinked acrylic resin beads is preferably in the range of 0.5 to 30% by weight in the total solid content of the curable resin composition. The range of 1 to 15% by weight is particularly preferable. When the blending amount is less than 0.5% by weight, the antiglare effect is insufficient, and when it exceeds 30% by weight, durability of the roughened layer such as wear resistance and environmental resistance is deteriorated. .

  It is preferable that the haze value of the protective layer provided with the antiglare property thus obtained is in the range of 6 to 45%. If the haze value of the antiglare protective layer is less than 6%, a sufficient antiglare effect may not appear. If it exceeds 45%, when the composite polarizing plate is applied to a liquid crystal display device, the screen of the liquid crystal display device may be whitened, resulting in a decrease in image quality.

  The haze value of the protective layer can be measured according to JIS K 7136, for example, using a haze / transmittance meter HM-150 (manufactured by Murakami Color Research Laboratory Co., Ltd.). In measuring the haze value, a cured product of a curable resin composition obtained by forming a cured product of a curable resin composition on a polyethylene terephthalate (PET) film and peeling the PET film is used to warp the film. For example, it is preferable to use a measurement sample bonded to a glass substrate using an optically transparent adhesive.

  Further, a functional layer such as a conductive layer, a hard coat layer, and a low reflection layer can be further laminated on the second protective layer. Moreover, the resin composition which can form the layer which combines these functions as a curable resin composition for forming a protective layer can also be selected.

  The thickness of the protective layer is preferably from 0.1 to 10 μm, more preferably from 1 to 5 μm. If the thickness of the protective layer is less than 0.1 μm, the durability of the protective layer may be insufficient. If it exceeds 10 μm, the effect of reducing the thickness and weight of the composite polarizing plate may be reduced.

(Retardation film)
The retardation film laminated | stacked on the 1st protective layer side of the polarizing plate which consists of a 1st protective layer, a polarizing film, and a 2nd protective layer consists of olefin resin, and _nx > _nz > n _It is a so-called biaxial retardation film that satisfies the relationship of _y . The olefin resin is a chain aliphatic olefin such as ethylene and propylene, or a structural unit derived from an alicyclic olefin such as norbornene or a substituted product thereof (hereinafter collectively referred to as norbornene monomer). It becomes resin. The olefin resin may be a copolymer using two or more kinds of monomers.

  Among them, as the olefin resin, a cyclic olefin resin that is a resin mainly containing a structural unit derived from an alicyclic olefin is preferably used. Typical examples of the alicyclic olefin constituting the cyclic olefin resin include a norbornene monomer. Norbornene is a compound in which one carbon-carbon bond of norbornane is a double bond, and according to IUPAC nomenclature, it is named bicyclo [2,2,1] hept-2-ene. is there. Examples of norbornene substitution products include 3-substitution, 4-substitution, and 4,5-di-substitution, with the norbornene double bond position being in the 1,2-position. Dicyclopentadiene, dimethanooctahydronaphthalene and the like can also be mentioned.

  The cyclic olefin-based resin may or may not have a norbornane ring in its structural unit. Examples of the norbornene-based monomer that forms a cyclic olefin-based resin having no norbornane ring as a structural unit include, for example, those that become a 5-membered ring by ring opening, typically norbornene, dicyclopentadiene, 1- or 4- Examples include methyl norbornene and 4-phenyl norbornene. When the cyclic olefin resin is a copolymer, the arrangement state of the molecules is not particularly limited, and may be a random copolymer, a block copolymer, or a graft copolymer. It may be a polymer.

  More specific examples of cyclic olefin resins include, for example, ring-opening polymers of norbornene monomers, ring-opening copolymers of norbornene monomers and other monomers, addition of maleic acid and cyclopentadiene, etc. Examples of the polymer-modified products made and hydrogenated polymers or copolymers; addition polymers of norbornene monomers, addition copolymers of norbornene monomers and other monomers, and the like. Examples of other monomers in the case of a copolymer include α-olefins, cycloalkenes, and non-conjugated dienes. Moreover, the cyclic olefin resin may be a copolymer using one or more of norbornene monomers and other alicyclic olefins.

  Among the specific examples, as the cyclic olefin-based resin, a resin obtained by hydrogenating a ring-opening polymer or a ring-opening copolymer using a norbornene-based monomer is preferably used. Such a cyclic olefin-based resin is a film that has been subjected to a stretching treatment in advance, and a shrinkable film having a predetermined shrinkage rate is bonded to the film to cause heat shrinkage. A retardation film having a value can be provided. Commercial products of cyclic olefin resins using such norbornene-based monomers are all sold under the trade name “ZEONEX”, “ZEONOR”, and JSR Corporation sold by Nippon Zeon Co., Ltd. There is "Arton" etc. Commercially available products of these cyclic olefin-based resin films and stretched films are also available, for example, “Zeonor Film” and JSR Co., Ltd., both of which are sold by Nippon Zeon Co., Ltd. There are “Arton Film” sold, and “Essina” sold by Sekisui Chemical Co., Ltd.

  In addition, as the retardation film used in the present invention, a film made of a mixed resin containing two or more kinds of olefin resins, or a film made of a mixed resin of an olefin resin and another thermoplastic resin can also be used. For example, examples of the mixed resin containing two or more types of olefin resins include a mixture of a cyclic olefin resin and a chain aliphatic olefin resin as described above. When a mixed resin of an olefin resin and another thermoplastic resin is used, another thermoplastic resin is appropriately selected depending on the purpose. Specific examples include polyvinyl chloride resin, cellulose resin, polystyrene resin, acrylonitrile / butadiene / styrene copolymer resin, acrylonitrile / styrene copolymer resin, (meth) acrylic resin, polyvinyl acetate resin, polyvinyl chloride. Vinylidene resin, polyamide resin, polyacetal resin, polycarbonate resin, modified polyphenylene ether resin, polybutylene terephthalate resin, polyethylene terephthalate resin, polyphenylene sulfide resin, polysulfone resin, polyethersulfone resin, polyether Examples include ether ketone resins, polyarylate resins, liquid crystalline resins, polyamideimide resins, polyimide resins, and polytetrafluoroethylene resins. These thermoplastic resins can be used alone or in combination of two or more. The thermoplastic resin may be used after any appropriate polymer modification. Examples of the polymer modification include copolymerization, crosslinking, molecular terminal modification, and stereoregularity imparting.

  When a mixed resin of an olefin resin and another thermoplastic resin is used, the content of the other thermoplastic resin is usually about 50% by weight or less and preferably about 40% by weight or less based on the whole resin. By setting the content of other thermoplastic resins within this range, the retardation value film has a small absolute value of the photoelastic coefficient, exhibits good wavelength dispersion characteristics, and is excellent in durability, mechanical strength, and transparency. Can be obtained.

  Such an olefin resin can be formed into a film by a casting method from a solution, a melt extrusion method, or the like. When a film is formed from two or more kinds of mixed resins, the film forming method is not particularly limited. For example, a uniform solution obtained by stirring and mixing resin components with a solvent at a predetermined ratio is used. A method for producing a film by a casting method, a method for producing a film by a melt extrusion method by melting and mixing resin components at a predetermined ratio, and the like are employed.

  The film made of the olefin-based resin may contain other components such as a residual solvent, a stabilizer, a plasticizer, an anti-aging agent, an antistatic agent, and an ultraviolet absorber as necessary, as long as the object of the present invention is not impaired. You may contain. Moreover, a leveling agent can also be contained in order to reduce the surface roughness.

  The retardation film made of the olefin resin film used in the present invention satisfies the following formulas (1) and (2) with respect to light having a wavelength of 590 nm.

_{100nm ≦ (n x -n y)} × d ≦ 300nm (1)
_{0.1 ≦ (n x -n z)} / (n x -n y) ≦ 0.7 (2)
Here, n _x, n _y and n _z-plane slow axis direction of each retardation film, a plane fast axis direction and the refractive index in the thickness direction, d is the thickness of the retardation film . (N _x -n _y) × d in the formula (1) is a plane retardation of the retardation film. Further, the above equation in _{(2) (n x -n z} ) / (n x -n y) value of the Nz coefficient. By using such a retardation film having specific refractive index anisotropy, the display characteristics of the liquid crystal cell can be suitably compensated over a wide angle when the composite polarizing plate is applied to a liquid crystal display device.

  The thickness d of the retardation film can be 20 to 500 μm, and preferably 20 to 300 μm. If the thickness is within this range, sufficient self-supporting property of the film can be obtained, and a wide range of retardation can be obtained.

  When the retardation film is used as a λ / 2 plate, the in-plane retardation with respect to light having a wavelength of 590 nm is preferably 200 to 300 nm, and more preferably 240 to 300 nm. By setting the in-plane retardation for light having a wavelength of 590 nm to about ½ of the wavelength, the display characteristics of the liquid crystal display device can be further improved. When the retardation film is used as a λ / 2 plate, the thickness is preferably from 80 to 160 μm, more preferably from 85 to 145 μm, in order to sufficiently align in the thickness direction. In addition, this retardation film may be used as a λ / 4 plate.

  The Nz coefficient of the retardation film is in the range of 0.1 to 0.7, and preferably in the range of 0.3 to 0.6. When the Nz coefficient of the retardation film is around 0.5, the retardation value can be made almost constant regardless of the angle, and the display characteristics of the liquid crystal display device can be further improved.

  A method for producing a retardation film having the retardation and refractive index characteristics is not particularly limited. For example, an olefin resin film is stretched and a shrinkable film having a predetermined shrinkage ratio is pasted thereon. A method of heat shrinking together, a method of heat shrinking a stretched film bonded with the shrinkable film simultaneously with a further stretching treatment, and a shrinkable film having a predetermined shrinkage rate are pasted on an unstretched film made of an olefin resin In addition, a method of heating and shrinking simultaneously with the stretching treatment is employed.

(Adhesive layer)
The pressure-sensitive adhesive layer (pressure-sensitive adhesive layer 105 in FIG. 1) is a layer responsible for adhesion between the first protective layer of the polarizing plate and the retardation film. In this invention, the adhesive which comprises an adhesive layer has a storage elastic modulus of 0.1 Mpa or more in 80 degreeC, Preferably the highly elastic adhesive which is 0.15 Mpa-10 Mpa is used. The storage elastic modulus at a temperature of 23 ° C. of this highly elastic pressure-sensitive adhesive is preferably 0.1 MPa or more, and more preferably 0.2 to 10 MPa. Since the storage elastic modulus generally decreases as the temperature increases, if the storage elastic modulus of the material measured at 80 ° C. is 0.1 MPa or more, the storage elastic modulus of the same material usually measured at 23 ° C. Indicates a higher value.

  Here, the storage elastic modulus (dynamic elastic modulus) is a commonly used term for viscoelasticity measurement, and gives a strain or stress that changes (vibrates) over time to a sample. This is a value obtained by measuring the mechanical properties of the sample by measuring the stress or strain generated by (dynamic viscoelasticity measurement), and the phase of the strain is 90 degrees out of phase with the stress component. The elastic modulus is calculated from the strain having the same phase as the stress. The storage elastic modulus can be measured using a commercially available viscoelasticity measuring apparatus, for example, a dynamic viscoelasticity measuring apparatus (Dynamic Analyzer RDA II: manufactured by REOMETRIC) as shown in the examples described later. For the temperature control of the viscoelasticity measuring apparatus, various known temperature control devices such as a circulating thermostat, an electric heater, a Peltier element, and the like are used, and thereby the temperature at the time of measurement can be set.

  The pressure-sensitive adhesive used in a normal image display device or an optical film applied thereto has a storage elastic modulus of about 0.1 MPa at most at 23 ° C. (room temperature), but the pressure-sensitive adhesive used in the present invention is stored. The elastic modulus is a high value as described above. Such a high storage modulus, that is, by using a hard pressure-sensitive adhesive, can compensate for a lack of cohesive force when placed in a high temperature environment or when a high temperature environment and a low temperature environment are repeated. The dimensional change accompanying the shrinkage | contraction of the polarizing film sometimes generated can be suppressed. By this action, the composite polarizing plate of the present invention has good durability. Also, by using such a pressure-sensitive adhesive having a high storage modulus, the adhesion between the first protective layer made of a cured product of the curable resin composition and the retardation film made of an olefin resin is extremely good. become.

  As a specific adhesive used in the present invention, for example, an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether or the like can be used as a resin component. Among them, like acrylic polymers, it has excellent optical transparency, retains appropriate wettability and cohesion, has excellent adhesion to the base material, and has weather resistance, heat resistance, etc. It is preferable to select and use a material that does not cause peeling problems such as floating and peeling under the conditions of heating and humidification.

  The acrylic polymer is not particularly limited, but (meth) acrylic such as butyl (meth) acrylate, ethyl (meth) acrylate, isooctyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, etc. Acid ester polymers and copolymer polymers using two or more of these (meth) acrylic acid esters are preferably used. Moreover, polar monomers are usually copolymerized with these acrylic polymers. Examples of polar monomers include (meth) acrylic acid, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylamide, and 2-N, N-dimethylaminoethyl (meth). Mention may be made of monomers having polar functional groups such as carboxyl groups, hydroxyl groups, amide groups, amino groups, and epoxy groups, such as acrylates and glycidyl (meth) acrylates.

  These acrylic polymers can be used alone as a pressure-sensitive adhesive, but are usually a pressure-sensitive adhesive composition containing a crosslinking agent. As the crosslinking agent, a divalent or polyvalent metal ion that forms a carboxylic acid metal salt with a carboxyl group, a polyamine compound that forms an amide bond with a carboxyl group, Examples include polyepoxy compounds and polyol compounds that form an ester bond with a carboxyl group, and polyisocyanate compounds that form an amide bond with a carboxyl group. Of these, polyisocyanate compounds are preferably used.

  In the present invention, means for increasing the storage elastic modulus of the highly elastic pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, the pressure-sensitive adhesive component may be an oligomer, specifically Is preferably employed a method of blending urethane acrylate oligomer. Furthermore, a method of irradiating an adhesive containing such a urethane acrylate oligomer with an energy ray and curing it is more preferably employed because it exhibits a higher storage elastic modulus. A pressure-sensitive adhesive containing a urethane acrylate-based oligomer or a pressure-sensitive adhesive with a separator obtained by coating it on a support film (separator) and curing it with ultraviolet rays is known and can be obtained from a pressure-sensitive adhesive manufacturer.

  In order to adjust the adhesive force, cohesive force, viscosity, elastic modulus, glass transition temperature, etc. of the adhesive, if necessary, in addition to the resin component, crosslinking agent and oligomer, Add appropriate additives such as natural and synthetic resins, tackifier resins, antioxidants, UV absorbers, dyes, pigments, antifoaming agents, corrosion inhibitors, and photoinitiators. You can also Examples of the ultraviolet absorber include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like.

  Moreover, the highly elastic adhesive used by this invention can mix | blend a light-diffusion agent, and can be used as a light-diffusable adhesive. The light diffusing agent used here may be fine particles having a refractive index different from that of a resin component such as an acrylic polymer constituting the pressure-sensitive adhesive layer, and fine particles made of an inorganic compound or fine particles made of an organic compound (polymer) are used. Can do.

  Examples of the fine particles made of an inorganic compound include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45). Examples of the fine particles comprising an organic compound (polymer) include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate / styrene copolymer resin beads (refractive index). 1.50), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1.46) ), And silicone resin beads (refractive index 1.46).

  Since the resin component constituting the pressure-sensitive adhesive layer including the acrylic polymer usually has a refractive index of around 1.4, the light diffusing agent to be blended is appropriately selected from those having a refractive index of about 1-2. Just choose. The refractive index difference between the resin component constituting the pressure-sensitive adhesive layer and the light diffusing agent is usually 0.01 or more, and from the viewpoint of brightness and visibility of the liquid crystal display device, 0.01 to 0.5 is preferable. The fine particles used as the light diffusing agent are preferably spherical and those close to monodisperse. For example, fine particles having an average particle diameter of about 2 to 6 μm are preferably used.

  The blending amount of the light diffusing agent is appropriately determined in consideration of the haze value required for the light diffusing pressure-sensitive adhesive layer in which it is blended, the brightness of the liquid crystal display device to which it is applied, etc. The amount is about 3 to 30 parts by weight with respect to 100 parts by weight of the resin component constituting the pressure-sensitive adhesive layer.

  Further, the haze value required for the light diffusive pressure-sensitive adhesive layer secures the brightness of the liquid crystal display device to which the composite polarizing plate obtained by using it is applied, and causes blurring and blurring of the display image. From the viewpoint of making it difficult, 20 to 80% is preferable. The haze is a value defined by JIS K 7105 and expressed by (diffuse transmittance / total light transmittance) × 100 (%).

  The thickness of the pressure-sensitive adhesive layer (including the case where it is a light diffusive pressure-sensitive adhesive layer) is determined according to the adhesive force and the like, but is usually 1 to 40 μm. Furthermore, the thickness of the composite polarizing plate using it maintains good workability and exhibits high durability, and when the liquid crystal display device using the composite polarizing plate is viewed from the front or obliquely. 3 to 25 μm is preferable from the viewpoint of maintaining the brightness of the image and making the display image less likely to bleed or blur.

<Method for producing composite polarizing plate>
Although the manufacturing method of the composite polarizing plate of this invention is not specifically limited, For example, the method of manufacturing through the following process is employ | adopted preferably.
(A) producing a polarizing plate comprising a first protective layer, a polarizing film and a second protective layer;
(B) The process of laminating | stacking a polarizing plate and retardation film through an adhesive layer.

  In the step (a), the order of forming the first and second protective layers on the polarizing film is not particularly limited, and the second protective layer is formed after forming the first protective layer on the polarizing film. The first protective layer may be formed after forming the second protective layer on the polarizing film, or the first protective layer and the second protective layer may be formed on the polarizing film. May be performed simultaneously. When simultaneously forming the first protective layer and the second protective layer on the polarizing film, the first protective layer and the second protective layer are formed by one irradiation of the active energy ray or heating. Since the formation can be performed at the same time, the manufacturing process can be simplified.

  Specifically, although not particularly limited, for example, the coating layer of the curable resin composition is formed by applying the curable resin composition on a substrate and drying it as necessary. After preparing two base materials, the two base materials and a polarizing film are pasted so that the coating layer side becomes a pasting surface, and visible light, ultraviolet rays, X-rays, or Adopting a method of removing the substrate after curing the coating layer made of the curable resin composition between the substrate and the polarizing film by irradiating or heating an active energy ray such as an electron beam Can do.

  Examples of the substrate include metal belts, glass plates, polyethylene terephthalate films, polycarbonate films, triacetyl cellulose films, cyclic olefin resin films, and polystyrene films. The surface on which the curable resin composition of the base material is coated may be subjected to a peeling treatment.

  In addition, by directly applying the curable resin composition to both sides of the polarizing film and irradiating with active energy rays or heating, the coating layer made of the curable resin composition is cured to form a protective layer. The method to do is also adopted.

  When the curable resin composition is cured by irradiation with active energy rays, ultraviolet rays are preferably used. Specific examples of the ultraviolet light source include a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, a black light lamp, and a metal halide lamp. The irradiation intensity and irradiation amount of active energy rays such as ultraviolet rays may be appropriately selected so as to sufficiently activate the polymerization initiator and not adversely affect the protective layer obtained by curing and the polarizing film.

  Further, when the curable resin composition is cured by heating, it can be heated by a generally known method, and the temperature and time can be obtained by sufficiently activating the polymerization initiator and curing. What is necessary is just to select suitably so that a protective layer and a polarizing film may not be adversely affected.

  In the step (b), the method of laminating the polarizing plate and the retardation film via the pressure-sensitive adhesive layer is not particularly limited, but usually, the pressure-sensitive adhesive is usually first applied to the surface of the polarizing plate or the retardation film. A layer is formed. The pressure-sensitive adhesive layer can be formed by a method in which a pressure-sensitive adhesive solution is applied to the first protective layer of the polarizing plate or the retardation film and dried, and the mold release treatment of the support film (separator) subjected to the mold release treatment It can also be formed by a method in which a pressure-sensitive adhesive layer is formed on the surface (pressure-sensitive adhesive with a separator), and this is bonded to the surface of the first protective layer or retardation film of the polarizing plate on the pressure-sensitive adhesive layer side. As the pressure-sensitive adhesive solution, for example, a 10 to 40% by weight solution obtained by dissolving or dispersing the raw material constituting the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate is used. When the pressure-sensitive adhesive layer is formed by a method of applying a pressure-sensitive adhesive solution to the first protective layer or retardation film of the polarizing plate and drying, treatment with a release agent such as a silicone type is performed on the formed pressure-sensitive adhesive layer. A separator made of the applied resin film may be laminated and temporarily protected until the other film or layer is bonded.

  Furthermore, when the pressure-sensitive adhesive layer is formed on the surface of the polarizing plate or the retardation film, a treatment for improving the adhesion to the pressure-sensitive adhesive layer forming surface of the polarizing plate or the retardation film, for example, corona treatment, as necessary. The same treatment may be applied to the surface of the pressure-sensitive adhesive layer bonded to the polarizing plate or the retardation film.

  The polarizing plate and the retardation film are bonded by a conventionally known technique. For example, the slow axis of the retardation film is orthogonal to the polarizing transmission axis of the polarizing film using a bonding roll or the like. Or the method of laminating | stacking so that it may become parallel, and the method of bonding so that the slow axis of a retardation film may become a predetermined angle with respect to the polarization transmission axis of a polarizing film are employ | adopted. Moreover, the method of aligning the long side direction from the roll which wound up the long polarizing plate and the phase difference plate, respectively, and laminating | bonding continuously is also preferably employ | adopted from a viewpoint of productivity.

  The composite polarizing plate of the present invention thus configured may further be provided with an adhesive layer on the outside of the retardation film. This pressure-sensitive adhesive layer can be suitably used for bonding with other members such as a liquid crystal cell. In order to bond the composite polarizing plate to the liquid crystal cell, it is usually arranged so that the retardation film side of the composite polarizing plate faces the liquid crystal cell.

<Liquid crystal display device>
The composite polarizing plate of this invention can bond the retardation film side and a liquid crystal cell through an adhesive layer, and can be set as a liquid crystal display device. The liquid crystal display device of the present invention may have a configuration in which the composite polarizing plate of the present invention is disposed on both surfaces of the liquid crystal cell, or may have a configuration in which the composite polarizing plate of the present invention is disposed on one side of the liquid crystal cell. . In the latter case, another conventionally known polarizing plate may be disposed on the side where the composite polarizing plate of the present invention is not disposed. The operation mode of the liquid crystal cell applied to the liquid crystal display device of the present invention is favorably optically compensated by the refractive index characteristic of the composite polarizing plate of the present invention. A Plane-Switching) cell is preferred.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the examples, “part” and “%” representing the amount used or content are based on weight unless otherwise specified. In the following examples, the storage elastic modulus was measured by the following method.

[Method for measuring storage modulus]
The storage elastic modulus (G ′) of the pressure-sensitive adhesive is a columnar test piece having a diameter of 8 mm × thickness of 1 mm made of the pressure-sensitive adhesive to be measured, and a dynamic viscoelasticity measuring device (Dynamic Analyzer RDA II: manufactured by REOMETRIC). The initial strain was set to 1 N by the torsional shear method with a frequency of 1 Hz, and the measurement was performed under the conditions of a temperature of 23 ° C. or 80 ° C.

(Preparation of active energy ray-curable resin composition I)
The following components were mixed to obtain an active energy ray-curable resin composition I.

3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (Daicel Chemical Industries, Celoxide 2021P) 35 parts Bis (3-ethyl-3-oxetanylmethyl) ether (Toagosei Co., Ltd., Aron) Oxetane OXT-221) 15 parts Diacrylate of acetal compound of hydroxypivalaldehyde and trimethylolpropane (Shin-Nakamura Chemical Co., Ltd., A-DOG) 50 parts 2-hydroxy-2-methyl-1-phenylpropane -1-one (Ciba, DAROCUR 1173, radical photopolymerization initiator)
2.5 parts 4,4′-bis (diphenylsulfonio) diphenyl sulfide Bishexafluorophosphate photocationic polymerization initiator (Daicel Cytec Co., Ltd., UVACURE 1590) 2.5 parts Silicone leveling agent (Toray -Dow Corning Co., Ltd., SH710)
0.2 parts.

  In addition, said A-DOG (diacrylate of the acetal compound of a hydroxypivalaldehyde and a trimethylol propane) is a compound which has a structure of following Formula.

In the following Examples and Comparative Examples, the following were used as pressure-sensitive adhesives.
(Adhesive A: High elastic adhesive)
The pressure-sensitive adhesive A is a pressure-sensitive adhesive in which a urethane acrylate oligomer is blended with a copolymer of butyl acrylate and acrylic acid, and an isocyanate cross-linking agent is further added. When the storage elastic modulus of the pressure-sensitive adhesive A was measured by the above method, it was 0.40 MPa at 23 ° C. and 0.18 MPa at 80 ° C. In the examples to be described later, an organic solvent solution of the adhesive A was applied to a release treatment surface of a 38 μm thick polyethylene terephthalate film (separator) subjected to a release treatment, and was produced by drying. A pressure-sensitive adhesive sheet A, which is a sheet-like pressure-sensitive adhesive with a separator in which a layer of pressure-sensitive adhesive A having a thickness of 15 μm was formed on the surface of the separator, was used.

(Adhesive B: Low elasticity adhesive)
The pressure-sensitive adhesive B is a commercially available pressure-sensitive adhesive and does not contain a urethane acrylate oligomer. When the storage elastic modulus of the adhesive B was measured by the above method, it was 0.05 MPa at 23 ° C. and 0.04 MPa at 80 ° C. In the examples and comparative examples described later, a commercially available separator in which a release treatment surface of a 38 μm-thick polyethylene terephthalate film (separator) subjected to a release treatment is provided with a layer of a pressure-sensitive adhesive B having a thickness of 15 μm. The pressure-sensitive adhesive sheet B which is a sheet-like pressure-sensitive adhesive was used.

(Adhesive C: Low elasticity adhesive)
The pressure-sensitive adhesive C is a commercially available pressure-sensitive adhesive and does not contain a urethane acrylate oligomer. When the storage elastic modulus of the adhesive C was measured by the above method, it was 0.10 MPa at 23 ° C. and 0.04 MPa at 80 ° C. In the examples and comparative examples described later, a commercially available separator in which a release treatment surface of a 38 μm thick polyethylene terephthalate film (separator) subjected to a release treatment is provided with a layer of pressure sensitive adhesive C having a thickness of 15 μm. The pressure-sensitive adhesive sheet C which is a sheet-like pressure-sensitive adhesive was used.

<Example 1>
(A) Production of polarizing plate A polyvinyl alcohol film having a thickness of 75 μm made of polyvinyl alcohol having an average degree of polymerization of about 2,400 and a degree of saponification of 99.9 mol% or more is uniaxially stretched about 5 times by dry method, While maintaining the tension state, the sample was immersed in pure water at 60 ° C. for 1 minute, and then immersed in an aqueous solution having a weight ratio of iodine / potassium iodide / water of 0.05 / 5/100 at 28 ° C. for 60 seconds. Then, it was immersed in an aqueous solution having a weight ratio of potassium iodide / boric acid / water of 8.5 / 8.5 / 100 at 72 ° C. for 300 seconds. Subsequently, it was washed with pure water at 26 ° C. for 20 seconds and then dried at 65 ° C. to obtain a polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol.

  On one side of a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., ester film E5100), an active energy ray-curable resin composition I is applied using a coating machine (manufactured by Daiichi Rika Co., Ltd., bar coater). Coated. Next, a PET film having a coating film of the active energy ray-curable resin composition I on both surfaces of the polarizing film is applied to a bonding apparatus (manufactured by Fuji Plastics Co., Ltd.) so that the coating film side becomes a bonding surface with the polarizing film. , LPA3301).

This bonded product was irradiated with ultraviolet rays from one PET film side with an integrated light quantity of 1500 mJ / cm ² by a D bulb manufactured by Fusion UV Systems, and the active energy ray-curable resin composition disposed on both surfaces of the polarizing film. The coating of I was cured. Thereafter, the PET film was peeled off to produce a polarizing plate having a transparent protective layer provided on both sides of the polarizing film. In addition, it was 36 micrometers when the thickness of the polarizing plate was measured using the film thickness measuring device (made by Nikon Corporation, ZC-101), and the thickness of the transparent protective layer was 4 micrometers, respectively.

In addition, the in-plane retardation R _e and the thickness direction retardation R _th of the protective layer made of the cured product of the active energy ray-curable resin composition I with respect to light having a wavelength of 590 nm were measured using a measuring instrument “manufactured by Oji Scientific Instruments”. KOBRA-21ADH "result of measurement using a in-plane retardation R _e is 0.7 nm, retardation R _th in the thickness direction was 5.5 nm. In measuring the retardation, a cured product film of the active energy ray curable resin composition I obtained by forming a cured product of the active energy ray curable resin composition I on the PET film and peeling the PET film is used. Used as a measurement sample.

(B) Lamination of retardation film A film having a thickness of 80 μm obtained by longitudinally uniaxially stretching a cyclic olefin-based resin film [Zeonor film manufactured by Nippon Zeon Co., Ltd.] comprising a hydrogenated product of a ring-opening polymer of a norbornene-based monomer. Was used as a retardation film precursor. The film has a glass transition temperature of 136 ° C., a photoelastic coefficient of 3.1 × 10 ⁻¹² m ² / N, an in-plane retardation with respect to light having a wavelength of 590 nm is 300 nm, and a retardation in the thickness direction is 145 nm. there were. A shrinkable film (a biaxially stretched film (thickness 60 μm) made of a polypropylene resin having a transverse stretching ratio larger than the longitudinal stretching ratio) is pasted on both sides of this uniaxially stretched film via an acrylic adhesive layer having a thickness of 25 μm. Combined. After that, while holding the width direction of the film with a pin tenter, the film is sequentially passed through an air circulation type thermostatic oven at 175 ° C ± 1 ° C and an air circulation type thermostatic oven at 160 ° C ± 1 ° C, and shrinks 0.70 times in the width direction. I let you. At this time, the shrinkage ratio in the longitudinal direction was 0.92. Then, the shrinkable film stuck on both surfaces was peeled off together with the pressure-sensitive adhesive layer to obtain a retardation film made of a cyclic olefin resin. The retardation film thus obtained had a thickness of 107 μm, an in-plane retardation with respect to light having a wavelength of 590 nm, 241.9 nm, and an Nz coefficient of 0.49.

After the corona treatment was performed on the retardation film thus obtained at an irradiation amount of 16.8 kJ / m ² , the corona treatment surface and the transparent protective layer side of the polarizing plate were bonded via the adhesive sheet A. The composite polarizing plate of the present invention was obtained. The appearance of the composite polarizing plate thus obtained was good with no film floating or peeling, no bubbles or the like.

  The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) using an adhesive sheet B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to make the composite polarizing plate into glass. When the heat shock test is repeated for 100 cycles in this state, it is placed in a −35 ° C. atmosphere for 30 minutes, then transferred to a + 85 ° C. atmosphere for 30 minutes, and this is repeated 100 cycles. Even afterwards, no defects are observed, a good state is maintained, and high durability performance is achieved.

<Comparative Example 1>
The adhesive which bonds a polarizing plate and retardation film was changed to the adhesive sheet B, and others were carried out similarly to Example 1, and obtained the composite polarizing plate. The polarizing plate thus obtained was good in appearance with no film floating or peeling, no bubbles or the like.

  The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) using an adhesive sheet B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to make the composite polarizing plate into glass. When the heat shock test is repeated for 50 cycles in this state, placing in an atmosphere of −35 ° C. for 30 minutes, then moving to an atmosphere of + 85 ° C. and placing for 30 minutes in this state is one cycle. Bubbles are generated in the pressure-sensitive adhesive layer between the phase difference film and the glass, which is not practical.

<Comparative example 2>
The adhesive which bonds a polarizing plate and retardation film was changed to the adhesive sheet C, and others were carried out similarly to Example 1, and obtained the composite polarizing plate. The appearance of the polarizing plate thus obtained was good.

  The retardation film surface of the obtained composite polarizing plate is fixed to soda glass (used as a substitute for a liquid crystal cell) using an adhesive sheet B, and subjected to autoclave treatment at 50 ° C. for 20 minutes to make the composite polarizing plate into glass. When the heat shock test is repeated for 50 cycles in this state, placing in an atmosphere of −35 ° C. for 30 minutes, then moving to an atmosphere of + 85 ° C. and placing for 30 minutes in this state is one cycle. Bubbles are generated in the pressure-sensitive adhesive layer between the phase difference film and the glass, which is not practical.

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

  The composite polarizing plate of the present invention can be widely used as an optical member in various liquid crystal display devices. For example, a large liquid crystal display device such as a television, a computer display, a car navigation system, a mobile phone, and a mobile terminal device. It can be used as an optical member in a medium- and small-sized liquid crystal display device used for, for example.

  100 composite polarizing plate, 101 polarizing film, 102 second protective layer, 103 retardation film, 105 pressure-sensitive adhesive layer, 106 first protective layer, 110 polarizing plate.

Claims (8)

A second protective layer comprising a cured product of a curable resin composition containing an epoxy-based compound that is cured by irradiation with active energy rays or heating;
A polarizing film laminated on the second protective layer;
A first protective layer comprising a cured product of a curable resin composition containing an epoxy compound that is laminated on the polarizing film and cured by irradiation with active energy rays or heating;
An adhesive layer made of an adhesive having a storage elastic modulus of 0.1 MPa or more at a temperature of 80 ° C., which is laminated on the first protective layer;
And a retardation film composed of an olefin resin film satisfying the following formulas (1) and (2) for light having a wavelength of 590 nm, which is laminated on the pressure-sensitive adhesive layer.
_{100nm ≦ (n x -n y)} × d ≦ 300nm (1)
_{0.1 ≦ (n x -n z)} / (n x -n y) ≦ 0.7 (2)
(In the above formula (1) and (2), n _x, n _y and n _z represent the in-plane slow axis direction of each of the retardation film, the in-plane fast axis direction, and a refractive index in the thickness direction , D represents the thickness of the retardation film.)   The composite polarizing plate according to claim 1, wherein the epoxy compound has at least one epoxy group bonded to an alicyclic ring in the molecule. It said first protective layer and the second protective layer has an in-plane retardation R _e with respect to light having a wavelength of 590nm is not less 10nm or less, claims the absolute value of the retardation R _th in the thickness direction is 25nm or less 1 or 2 A composite polarizing plate according to 1.   The composite polarizing plate according to claim 1, wherein the olefin-based resin film is made of an olefin-based resin containing a structural unit derived from an alicyclic olefin.   The thickness of the said phase difference film is 20-300 micrometers, The composite polarizing plate in any one of Claims 1-4.   The thickness of the said adhesive layer is 1-40 micrometers, The composite polarizing plate in any one of Claims 1-5.   A liquid crystal display device comprising the composite polarizing plate according to claim 1 disposed on one or both sides of a liquid crystal cell.   The liquid crystal display device according to claim 7, wherein the liquid crystal cell is a horizontal electric field mode liquid crystal cell.

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