JP2013137521A - Composite retardation plate and composite polarizing plate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To adjust a film thickness of an adhesive layer to 10 μm or less while improving adhesion strength between a (meth)acrylic resin layer and a retardation plate when the retardation plate made of a cycloolefin-based resin film is laminated on the (meth)acrylic resin layer of the retardation plate in which the (meth)acrylic resin layer is an outermost surface.SOLUTION: There is provided a composite retardation plate 20 in which an adhesive layer 31 made of a cured product of an active energy ray curable resin composition and a second retardation plate 18 made of a cycloolefin-based resin film are laminated in this order on a (meth)acrylic resin layer 14 of a first retardation plate 10 having the (meth)acrylic resin layer 14 on the outermost surface. The adhesive layer 31 is formed of a curable resin composition having as curable components an N-substituted (meth)acrylamide and a compound having a (meta)acryloyloxy group in a molecule and a thickness of the adhesive layer 31 is made to be 10 μm or less. A composite polarizing plate 50 is prepared by laminating the composite retardation plate 20 on one surface of a polarizing film 42 and a protective film 44 on the other surface of the polarizing film 42.

Description

  In the present invention, a retardation plate having a (meth) acrylic resin layer and a retardation plate made of a cycloolefin resin film are laminated, and a composite retardation plate suitably used for a liquid crystal display device, and The present invention relates to a composite polarizing plate combined with a polarizing film.

  Liquid crystal display devices are used in various display devices by taking advantage of features such as low power consumption, operation at a low voltage, light weight, and thinness. The liquid crystal display device is composed of many materials such as a liquid crystal cell, a polarizing plate, a retardation plate, a light collecting sheet, a diffusion film, a light guide plate, and a light reflecting sheet. Therefore, improvements aimed at productivity, weight reduction, brightness improvement, and the like have been actively performed by reducing the number of constituent films or reducing the thickness of the film or sheet.

  The retardation plate is often produced by stretching a resin film. Although the main chain of the resin is aligned with the stretching axis by stretching, the resin having no bulky group in the side chain has the maximum refractive index in the stretching axis direction, and that direction becomes the slow axis. Such a resin is called a resin having a positive refractive index anisotropy, and a retardation film formed from the resin is sometimes called a positive retardation film. Recently, a stretched film of a cycloolefin resin having a small photoelastic coefficient is often used as a positive retardation plate. On the other hand, the resin having a bulky group in the side chain has the maximum refractive index in the side chain direction, that is, in the direction orthogonal to the stretching axis, and therefore the stretching axis direction becomes the fast axis. Such a resin is called a resin having negative refractive index anisotropy, and a retardation film formed from the resin is sometimes called a negative retardation film. As resins having negative refractive index anisotropy, styrene resins mainly containing styrene and (meth) acrylic resins mainly containing acrylic esters or methacrylic esters have been known. ing.

  The (meth) acrylic resin has low retardation. On the other hand, styrene-based resins have a problem in chemical resistance, mechanical strength, etc., although they have a large retardation. Therefore, there is an attempt to combine both. For example, Japanese Patent No. 4770176 (Patent Document 1) discloses a resin multilayer film in which a second layer made of a (meth) acrylic resin composition is laminated on both surfaces of a first layer made of a styrene resin by coextrusion. Describes that an in-plane retardation is imparted to form a retardation plate. JP 2009-175222 A (Patent Document 2) discloses a composite polarizing plate in which a retardation film made of a resin multilayer film disclosed in Patent Document 1 is laminated on a polarizing film via an adhesive layer. In doing so, it is described that a primer layer is interposed between the phase difference plate and the adhesive layer to increase the adhesive force between them.

  Furthermore, a retardation plate applied to a liquid crystal display device may be used by laminating two or more films from the viewpoint of optical compensation. In that case, from the viewpoint of workability, a pressure-sensitive adhesive made of an acrylic resin is generally used for bonding these films. For example, Japanese Patent Laid-Open No. 2010-217870 (Patent Document 3) describes the above Patent Document 1 through a pressure-sensitive adhesive layer on a first retardation plate made of an olefin resin typified by a cycloolefin resin. Is laminated on a polarizing film through an adhesive layer on the first retardation plate side to form a composite polarizing plate. Yes.

  On the other hand, it is also known that two kinds of adherends are bonded with an adhesive that is cured by irradiation with an active energy ray, typically UV light. For example, in Japanese Patent No. 2805225 (Patent Document 4), an acrylic reactive monomer or a reactive oligomer is used in order to bond a molded product of cycloolefin resin, or the molded product to a different material. A method is described in which both are bonded with an ultraviolet curable adhesive containing a photopolymerization initiator, and then the adhesive is cured by irradiating with ultraviolet rays. Japanese Patent Application Laid-Open No. 2005-62443 (Patent Document 5) describes a transparent substrate made of glass as a representative example and a retardation film made of an organic polymer material such as a cycloolefin resin. It is described that bonding is performed using an adhesive made of a resin, and the adhesive is cured by ultraviolet irradiation so that the thickness of the adhesive layer is 10 μm or less.

Japanese Patent No. 4770176 (Japanese Patent Laid-Open No. 2006-192737) JP 2009-175222 A JP 2010-217870 A Japanese Patent No. 2805225 (Japanese Patent Laid-Open No. 3-160079) JP 2005-62443 A

  In the case where an adhesive as disclosed in Patent Document 3 is used for laminating a cycloolefin-based resin film and a (meth) acrylic-based resin film, an adhesive of at least about 15 μm in order to maintain an appropriate adhesive strength. The thickness of the layer is necessary, which is a bottleneck in reducing the thickness of a liquid crystal panel or a liquid crystal display device. There is also an attempt to thin the pressure-sensitive adhesive layer, but when the cycloolefin-based resin film and the (meth) acrylic-based resin film are bonded with a pressure-sensitive adhesive having a thickness of 10 μm or less, the adhesive strength is not sufficient. When a laminated retardation plate itself, a composite polarizing plate with the laminated retardation plate attached to a polarizing film, or a liquid crystal panel with the composite polarizing plate attached to a liquid crystal cell glass is exposed to high temperatures, the film sufficiently contracts. Absorption could not be achieved, and defects such as floating or peeling between the film and the pressure-sensitive adhesive layer and foaming could occur.

  On the other hand, it is conceivable to use an acrylic UV curable resin as an adhesive for curing the cycloolefin resin film and the (meth) acrylic resin film, and to cure by UV irradiation. Even when the curable resin was used alone, it was difficult to obtain a sufficient adhesive force.

  An object of the present invention is to provide a composite retardation plate by laminating a retardation plate made of a cycloolefin resin film on the (meth) acrylic resin layer of the retardation plate having a (meth) acrylic resin layer on the outermost surface. In order to improve the adhesive strength between the (meth) acrylic resin layer and the cycloolefin resin film, the film thickness is set to 10 μm or less.

  Another problem of the present invention is that the composite retardation plate thus obtained is bonded to one surface of a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin, and the adhesive strength of each layer is sufficient. In addition, it is an object of the present invention to provide a composite polarizing plate with a reduced thickness.

  As a result of research, as a curable component, two specific types of (meth) acrylic compounds are combined to form an active energy ray-curable resin composition, and if this is used as an adhesive, a (meth) acrylic resin film and cyclohexane are used. The present inventors have found that high adhesive strength can be obtained between olefin resin films and have completed the present invention.

  That is, according to the present invention, an adhesive made of a cured product of an active energy ray-curable resin composition is attached to the (meth) acrylic resin layer of the first retardation plate having a (meth) acrylic resin layer on the outermost surface. A second phase difference plate composed of an agent layer and a cycloolefin-based resin film is laminated in this order, and the above active energy ray-curable resin composition contains N-substituted (meth) acrylamide and ( A compound retardation plate containing a compound having a (meth) acryloyloxy group as a curable component and having a thickness of 10 μm or less as the adhesive layer is provided.

  In this composite retardation plate, N-substituted (meth) acrylamide, which is one curable component constituting the active energy ray-curable resin composition, is preferably a compound represented by the following formula (I).

In the formula, Q ₁ represents a hydrogen atom or a methyl group, Q ₂ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Q ₃ has 1 to 6 carbon atoms which may have a hydroxyl group or an amino group. Represents an alkyl group, or Q ₂ and Q ₃ together form a 5- or 6-membered ring which may have an oxygen atom as a ring member together with the nitrogen atom to which they are bonded.

  In addition, the compound having a (meth) acryloyloxy group in the molecule, which is another curable component constituting the active energy ray-curable resin composition, has at least one (meth) acryloyloxy group in the molecule. In particular, it is preferable to contain simultaneously a compound having one (meth) acryloyloxy group in the molecule and a compound having two or more (meth) acryloyloxy groups in the molecule.

  In these composite retardation plates, the first retardation plate can be composed of a single film of (meth) acrylic resin, but in addition to the (meth) acrylic resin layer, the first retardation plate is composed of other resins. It can also be comprised with the laminated | multilayer film containing a phase difference expression layer. Also in this case, the 2nd phase difference plate which consists of a cycloolefin type-resin film is bonded by a (meth) acrylic-type resin layer via the active energy ray curable resin composition prescribed | regulated above. Therefore, when a 1st phase difference plate is comprised with a laminated | multilayer film, it makes it the outermost surface by which a (meth) acrylic-type resin layer is affixed on a cycloolefin type-resin film.

  When the first retardation plate is composed of the laminated film as described above, the (meth) acrylic resin layer usually has a glass transition temperature of 120 ° C. or lower, but the retardation development layer is made of glass of 120 ° C. or higher. It is preferable to use a resin having a transition temperature. From the viewpoint of realizing such a high glass transition temperature and a resin having a negative refractive index anisotropy, the retardation layer is preferably composed of a styrene resin. Moreover, it is advantageous from a viewpoint of film forming property that a (meth) acrylic-type resin layer contains a rubber particle.

  In particular, it is advantageous that the first retardation plate has a three-layer structure in which a (meth) acrylic resin layer is formed on both surfaces of the retardation developing layer. In this case, the thickness of the retardation developing layer and the (meth) acrylic resin layers formed on both surfaces thereof can be set in the range of about 5 to 100 μm.

  Further, according to the present invention, a protective film made of a thermoplastic resin is laminated on one surface of a polarizing film on which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin, through a second adhesive layer, On the other surface of the polarizing film, there is also provided a composite polarizing plate in which any of the above-mentioned composite retardation plates is laminated on the cycloolefin resin film side through a third adhesive layer.

  This composite polarizing plate can be combined with a liquid crystal cell to form a liquid crystal display panel. In this case, the composite polarizing plate is bonded to the liquid crystal cell on the composite retardation plate side, that is, on the first retardation plate side having the (meth) acrylic resin layer. Therefore, this liquid crystal display panel includes a liquid crystal cell and the above-described composite polarizing plate, and the composite polarizing plate is bonded to the liquid crystal cell on the composite retardation plate side.

  According to this invention, the 1st phase difference plate containing a (meth) acrylic-type resin layer and the 2nd phase difference plate which consists of a cycloolefin type resin film are pasted together via an adhesive. Since the thickness can be reduced as compared with the retardation plate, the composite retardation plate, and thus the liquid crystal panel can be reduced in thickness and weight. Moreover, the adhesiveness of a cycloolefin type resin film and a (meth) acrylic-type resin layer is also favorable.

It is a schematic sectional drawing which shows the example of the preferable layer structure of the composite phase difference plate which concerns on this invention. It is a schematic sectional drawing which shows the example of the preferable layer structure of the composite polarizing plate which concerns on this invention.

[Composite retardation plate]
The composite phase difference plate of the present invention is obtained from a cured product of an active energy ray-curable resin composition on the (meth) acrylic resin layer of the first phase difference plate having a (meth) acrylic resin layer on the outermost surface. A second retardation plate made of a cycloolefin-based resin film is laminated through an adhesive layer. Here, as for the 1st phase difference plate, the outermost surface stuck on the 2nd phase difference plate which consists of a cycloolefin type resin film is a (meth) acrylic-type resin layer, and phase difference was expressed. Anything is acceptable. Specifically, it may be a single film of (meth) acrylic resin, or may be a multilayer film including a phase difference expressing layer made of other resin in addition to the (meth) acrylic resin layer. . Especially, it is preferable that the (meth) acrylic-type resin layer is formed in the one or both surfaces of the phase difference expression layer which consists of resin different from (meth) acrylic-type resin, and the phase difference was expressed.

  As used herein, “(meth) acrylic resin” is a resin having (meth) acrylic acid ester as a main structural unit, as described in the section “Background Art”. Further, “(meth) acrylic acid” means that either acrylic acid or methacrylic acid may be used, and “(meth) acrylic ester” means that any of acrylic acid ester or methacrylic acid ester may be used. To do. Others In this specification, “(meth)” such as “(meth) acrylamide”, “(meth) acrylate”, “(meth) acryloyl”, etc. has the same meaning.

  An example of a preferred layer structure of the composite retardation plate according to the present invention is shown in a schematic sectional view in FIG. The composite retardation plate of the present invention will be described with reference to FIG. As shown in FIG. 1, an adhesive layer 31 and a second retardation plate 18 made of a cycloolefin resin film are laminated in this order on a first retardation plate 10 including a (meth) acrylic resin layer. The composite retardation plate 20 of the present invention is configured. And the adhesive bond layer 31 is formed with the hardened | cured material of an active energy ray curable resin composition. In the example shown in this figure, the first retardation plate 10 has a state in which (meth) acrylic resin layers 14 and 15 are formed on both surfaces of a retardation developing layer 12 that mainly contributes to the development of the retardation function. It has become.

  As described above, the (meth) acrylic resin itself has a negative refractive index anisotropy and gives a negative retardation plate by stretching. Therefore, the single film is made into the first retardation plate 10. It can be. If it demonstrates with reference to FIG. 1, the phase difference expression layer 12 and one (meth) acrylic-type resin layer 15 will be abbreviate | omitted, and let it be the 1st phase difference plate 10 only by the (meth) acrylic-type resin layer 14. FIG. be able to. However, as described above, since the (meth) acrylic resin itself has a low retardation, it is preferably used in combination with the retardation layer 12. In this case, the state in which the (meth) acrylic resin layer 14 is formed on one surface of the retardation developing layer 12, in other words, located away from the second retardation plate 18 made of a cycloolefin resin film in FIG. 1. The first retardation plate 10 can also be formed with the (meth) acrylic resin layer 15 omitted. However, as shown in FIG. 1, if the (meth) acrylic resin layers 14 and 15 are formed on both surfaces of the retardation developing layer 12, the respective (meth) acrylic resin layers 14 and 15 Since the role of the protective layer of the phase difference expression layer 12 is also fulfilled, it is preferable. Hereinafter, the adhesive used to form the first retardation plate 10, the second retardation plate 18, and the adhesive layer 31 that adheres both to the composite retardation plate 20 will be described in order. To do.

[First retardation plate]
As shown in FIG. 1, the first retardation plate 10 constituting the composite retardation plate 20 is preferably a retardation development layer 12 and one side thereof (a second retardation plate 18 made of a cycloolefin-based resin film). (Meth) acrylic resin layer 14 laminated on the side to be bonded), and more preferably, the retardation developing layer 12 and the (meth) acrylic resin layers 14 and 15 laminated on both surfaces thereof. Is provided. Thus, when providing a (meth) acrylic-type resin layer in the single side | surface or both surfaces of the phase difference expression layer 12, the phase difference expression layer 12 can be comprised with a styrene resin, for example. Since the styrenic resin has a bulky phenyl group in the side chain, the refractive index in the direction perpendicular to the stretching axis (the direction perpendicular to the stretching axis and the thickness direction in the plane) becomes large when uniaxially stretched. Refractive index anisotropy is shown. In addition, the phase difference is highly expressed. Therefore, a film made of styrene resin is suitable as the retardation developing layer 12 for providing a negative retardation plate. The negative retardation plate, a refractive index n _y in the refractive indices n _x a maximum refractive index direction in the plane (slow axis direction), a direction perpendicular thereto in the plane (fast axis direction), thickness direction when the refractive index of the set to n _z, has a relationship of _{n z ≒ n x> n y} , a film of Nz coefficient is almost 0 (zero). Here, the Nz coefficient is defined by the following equation (1).
Nz factor _{= (n x -n z) /} (n x -n y) (1)

  The styrenic resin can be a homopolymer of styrene or a derivative thereof, and can also be a binary or higher copolymer of styrene or a derivative thereof and another copolymerizable monomer. The styrene derivative is a compound in which a substituent is bonded to styrene. For example, o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, o-ethylstyrene, and p-ethylstyrene. Such as hydroxystyrene, tert-butoxystyrene, vinyl benzoic acid, o-chlorostyrene, and p-chlorostyrene, substituted with a hydroxyl group, alkoxy group, carboxyl group, halogen, etc. introduced into the benzene nucleus of styrene Examples include styrene. A terpolymer obtained by copolymerizing an acyclic olefin monomer and a cyclic olefin monomer with styrene or a styrene derivative can also be used. Among them, the styrene resin is preferably a copolymer of styrene or a styrene derivative and at least one monomer selected from acrylonitrile, maleic anhydride, methyl methacrylate, and butadiene, from the viewpoint of heat resistance. Similarly, from the viewpoint of heat resistance, the styrenic resin (retardation layer 12) preferably has a glass transition temperature of 120 ° C. or higher.

  The thickness of the retardation layer 12, particularly the retardation layer 12 made of a styrene resin, is preferably about 5 to 100 μm, more preferably about 10 to 100 μm. When the thickness is less than 5 μm, a sufficient retardation value is hardly exhibited by stretching. On the other hand, when the thickness exceeds 100 μm, the impact strength of the retardation plate tends to be weak and the change in retardation due to external stress tends to increase.

  Examples of the (meth) acrylic resin constituting the (meth) acrylic resin layers 14 and 15 include, for example, a methacrylic acid alkyl ester or a homopolymer of an acrylic acid alkyl ester, and a methacrylic acid alkyl ester and an acrylic acid alkyl ester. A copolymer etc. are mentioned. Specific examples of the methacrylic acid alkyl ester include methyl methacrylate, ethyl methacrylate, and propyl methacrylate, and specific examples of the acrylic acid alkyl ester include methyl acrylate, ethyl acrylate, and propyl acrylate. As such a (meth) acrylic resin, a commercially available (meth) acrylic resin can be used. As the (meth) acrylic resin, a so-called impact resistant (meth) acrylic resin may be used.

  By laminating the (meth) acrylic resin layers 14 and 15 on the retardation developing layer 12, the chemical resistance and mechanical strength of the first retardation plate 10 can be improved. In order to further improve the mechanical strength, it is also preferable that the (meth) acrylic resin layers 14 and 15 contain rubber particles. The rubber particles are preferably acrylic. Here, the acrylic rubber particles have rubber elasticity obtained by polymerizing an acrylic monomer mainly composed of an alkyl acrylate ester such as butyl acrylate or 2-ethylhexyl acrylate in the presence of a polyfunctional monomer. Particles. The acrylic rubber particles may be one in which such rubber elastic particles are formed as a single layer, or may be a multilayer structure having at least one rubber elastic layer. As the acrylic rubber particles having a multilayer structure, particles having rubber elasticity as described above are used as cores, and the periphery thereof is covered with a hard alkyl methacrylate ester polymer, or a hard alkyl methacrylate ester polymer. The core is covered with an acrylic polymer having rubber elasticity as described above, or the hard core is covered with a rubber elastic acrylic polymer, and the periphery thereof is hard alkyl methacrylate. Examples thereof include those covered with a polymer. The rubber particles formed of the elastic layer usually have an average diameter in the range of about 50 to 400 nm.

  The content of rubber particles in the (meth) acrylic resin layers 14 and 15 is usually about 5 to 50 parts by weight per 100 parts by weight of the (meth) acrylic resin. Since the (meth) acrylic resin and acrylic rubber particles are commercially available in a state where they are mixed, commercially available products thereof can be used. Examples of commercially available (meth) acrylic resins containing acrylic rubber particles include “HT55X” and “Technoloy S001” sold by Sumitomo Chemical Co., Ltd. “Technoloy S001” is sold in film form.

  The (meth) acrylic resin composition containing the rubber particles as described above generally has a glass transition temperature of 120 ° C. or lower. In the present invention, the (meth) acrylic resin composition has a glass transition temperature of 110 ° C. or lower. The product is preferably used.

  As described above, the glass transition temperature of the retardation developing layer 12 is preferably 120 ° C. or higher, while the glass transition temperature of the (meth) acrylic resin layers 14 and 15 is 120 ° C. or lower, particularly 110 ° C. or lower. Preferably there is. Moreover, it is preferable that both glass transition temperatures do not overlap and the phase difference expression layer 12 has a glass transition temperature higher than the (meth) acrylic-type resin layers 14 and 15. FIG. This is because it becomes easier to manufacture a retardation plate by coextrusion described later.

  The thickness of the (meth) acrylic resin layers 14 and 15 is preferably 5 to 100 μm, particularly 10 to 100 μm.

  The composite retardation plate 20 is formed, for example, by coextruding a resin that forms the retardation developing layer 12 and a resin that forms the (meth) acrylic resin layers 14 and 15, and then into a layer that becomes the retardation developing layer. It can produce by performing the extending | stretching process for providing in-plane phase difference. Moreover, after producing a single layer film separately from each of the resin forming the phase difference expressing layer 12 and the resin forming the (meth) acrylic resin layers 14 and 15, a laminated film is formed by heat fusion by heat lamination, It can also be produced by a method of stretching it. Stretching is not particularly limited as long as a desired in-plane retardation value is obtained, and can be, for example, longitudinal uniaxial stretching, tenter lateral uniaxial stretching, simultaneous biaxial stretching, sequential biaxial stretching, or the like.

  As described above, the composite retardation plate 20 preferably has a three-layer structure in which (meth) acrylic resin layers 14 and 15 are laminated on both surfaces of the retardation developing layer 12. In this case, these (meth) acrylic resin layers can have substantially the same thickness. By adopting a three-layer structure, the mechanical strength and chemical resistance of the retardation plate can be further improved. The total film thickness in the case of a three-layer structure is generally 15 μm or more, preferably 20 μm or more, more preferably 25 μm or more, and generally 200 μm or less, preferably 150 μm or less, more preferably 100 μm or less.

The first retardation plate 10 has an in-plane retardation Re in the range of 20 to 120 nm, and an Nz coefficient defined by the above equation (1) exceeding −2 and less than −0.5. Preferably there is. Plane retardation Re is a value obtained by multiplying the thickness of the film in-plane birefringence index, the refractive indices n _x and n _y of defined in relation to the previous equation (1) plane biaxial directions And the thickness d of the film is defined by the following formula (2). The thickness direction retardation Rth is a value obtained by multiplying the thickness direction birefringence by the thickness of the film, the in-plane biaxial refractive indices _nx and _ny , the thickness direction refractive index _nz , And the thickness d of the film is defined by the following formula (3).
Plane retardation value _{Re = (n x -n y)} × d (2)
Retardation value in the thickness direction Rth = _{[(n x + n y) /} 2-n z ] × d (3)

  The in-plane retardation Re, the thickness direction retardation Rth, and the Nz coefficient can be obtained by using various commercially available retardation meters. The phase difference and the Nz coefficient may be values at an arbitrary wavelength in the vicinity of the center of visible light, for example, between 500 and 600 nm. However, when the measurement wavelength is not particularly described in this specification, the value at the wavelength of 590 nm To do.

[Second retardation plate]
The second retardation plate 18 constituting the composite retardation plate 20 of the present invention is formed on the (meth) acrylic resin layer 14 formed on the outermost surface of the first retardation plate 10 as shown in FIG. And an adhesive layer 31 made of a cured product of the active energy ray-curable resin composition. Here, the second retardation plate is composed of a cycloolefin resin film. The cycloolefin-based resin is a thermoplastic resin having a monomer unit made of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene-based monomer, and is also called a thermoplastic cycloolefin-based resin. The cycloolefin-based resin may be a hydrogenated product of the above-mentioned cycloolefin ring-opening polymer or a ring-opening copolymer using two or more kinds of cycloolefins. Cycloolefin, chain olefin, vinyl It may be an addition polymer with an aromatic compound having a polymerizable double bond such as a group. A polar group may be introduced into the cycloolefin resin.

  When a copolymer of a cycloolefin and a chain olefin and / or an aromatic compound having a vinyl group is used, ethylene or propylene is used as the chain olefin, and styrene, α is used as the aromatic compound having a vinyl group. -Methylstyrene, nuclear alkyl-substituted styrene, etc. can be used respectively. In such a copolymer, the monomer unit composed of cycloolefin may be 50 mol% or less, and in that case, it is preferably about 15 to 50 mol%. In particular, when the second retardation plate is constituted by using a terpolymer composed of an aromatic compound having a cycloolefin, a chain olefin, and a vinyl group, the content of the monomer unit composed of the cycloolefin is as described above. Thus, the amount can be made relatively small. At this time, the content of the monomer unit composed of a chain olefin is usually 5 to 80 mol%, and the content of the monomer unit composed of an aromatic compound having a vinyl group is usually 5 to 80 mol%.

  An appropriate commercially available product can be used as the cycloolefin resin. For example, “TOPAS” produced by TOPAS ADVANCED POLYMERS GmbH in Germany, sold in Japan from Polyplastics, “Arton” sold from JSR, and sold by Nippon Zeon. “ZEONOR” and “ZEONEX”, and “Apel” (all are trade names) sold by Mitsui Chemicals. In order to form such a cycloolefin-based resin into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used.

  The cycloolefin resin film is uniaxially stretched or biaxially stretched to give a phase difference to obtain a phase difference plate. The draw ratio at this time is 1.1-5 times normally, Preferably it is 1.1-3 times. The retardation plate obtained by stretching is preferably thin, but if it is too thin, the strength tends to decrease and the workability tends to be inferior. On the other hand, if it is too thick, the transparency decreases, or the composite retardation plate or composite polarization plate is used. The weight of the plate tends to increase. From such a viewpoint, the thickness of the second retardation plate made of cycloolefin resin is generally 5 μm or more, preferably 10 μm or more, more preferably 15 μm or more, and generally 150 μm or less, preferably It is 100 μm or less, more preferably 80 μm or less.

  There is also a cycloolefin-based resin film that has been formed in advance and is commercially available in some cases with a phase difference. Among these, if it is a film before phase difference is provided, it is the second film in the present invention as a raw film of the second phase difference plate in the present invention, and if it is provided with phase difference. It can also be used as the retardation film itself. Examples of such commercially available cycloolefin resin films include “Zeonor Film” sold by Nippon Zeon Co., Ltd., “Arton Film” sold by JSR Corporation, Sekisui Chemical Co., Ltd. ( "Essina" and "SCA40" (all of which are trade names) sold by the company.

  The cycloolefin resin film contains additives such as residual solvents, stabilizers, plasticizers, anti-aging agents, antistatic agents, and ultraviolet absorbers as necessary, as long as the object of the present invention is not impaired. It may be. Further, a leveling agent can be contained in order to reduce the surface roughness.

  In the present invention, the second retardation plate 18 made of a cycloolefin-based resin film has an in-plane retardation Re in the range of 30 to 150 nm, and an Nz coefficient defined by the above formula (1) is 1. Preferably, it is in the range of more than 2 and less than 2.

  The 2nd phase difference plate which consists of a cycloolefin type resin film is stuck on the 1st phase difference plate containing a (meth) acrylic-type resin layer using the adhesive agent explained in full detail below. In adhering both, in order to improve adhesiveness, plasma treatment and corona treatment are performed on the adhesion surface of the retardation plate including the (meth) acrylic resin layer and / or the cycloolefin resin film bonded thereto. Surface treatment such as ultraviolet irradiation treatment, flame (flame) treatment, saponification treatment, solvent treatment, and primer treatment may be appropriately performed. Hereinafter, the adhesive used for adhering the retardation plate including the (meth) acrylic resin layer and the cycloolefin resin film will be described.

[Adhesive for attaching the first retardation plate and the second retardation plate]
In the present invention, active energy ray curing is used for adhering the (meth) acrylic resin layer 14 which is the outermost surface of the first retardation plate 10 and the second retardation plate 18 made of a cycloolefin resin film. A functional resin composition is used. The active energy ray-curable resin composition contains a compound that is cured by irradiation with active energy rays, that is, a curable component. In this invention, the composition which uses N-substituted (meth) acrylamide and the compound which has a (meth) acryloyloxy group in a molecule | numerator as a sclerosing | hardenable component is employ | adopted.

<N-substituted (meth) acrylamide>
N-substituted (meth) acrylamide is (meth) acrylamide having a substituent at the N-position. A typical example of the substituent is an alkyl group which may be further substituted, but may form a ring together with the nitrogen atom of (meth) acrylamide, and this ring is composed of a carbon atom and (meth) In addition to the nitrogen atom of acrylamide, you may have an oxygen atom as a ring member. Further, a substituent such as alkyl or oxo (═O) may be bonded to the carbon atom constituting the ring. N-substituted (meth) acrylamides can generally be prepared by reaction of (meth) acrylic acid or its chloride with a primary or secondary amine.

The N-substituted (meth) acrylamide is particularly preferably the one represented by the formula (I). In the above formula (I) representing a suitable N-substituted (meth) acrylamide, when Q ₂ is an alkyl group and Q ₃ is an alkyl group optionally having a hydroxyl group or an amino group, the respective alkyl The group may be linear or branched as long as it has 3 or more carbon atoms. When Q ₃ is an alkyl group having a hydroxyl group, this corresponds to a hydroxyalkyl group. When Q ₃ is an alkyl group having an amino group, an aminoalkyl group, an N-alkylaminoalkyl group, or an N, N-dialkylaminoalkyl group corresponds to this. When Q ₂ and Q ₃ together form a 5-membered ring or 6-membered ring which may have an oxygen atom as a ring member together with the nitrogen atom to which they are bonded, the 5-membered ring or 6-membered ring An example of a ring in the form of a group leading to carbonyl (C═O) at the N-position is 1-pyrrolidinyl (C ₄ H ₈ N—), 2-oxazolidinon-3-yl (C ₂ H ₄ OC ( = O) N-), N- piperidino (C ₅ H _10), morpholino _{(C 2 H 4 OC 2 H} 4 N-) , and the like.

Specific examples of N-substituted (meth) acrylamides corresponding to formula (I), wherein Q ₂ is a hydrogen atom and Q ₃ is an alkyl group include N-methyl (meth) acrylamide, N-ethyl (meta ) Acrylamide, N-isopropyl (meth) acrylamide, N-butyl (meth) acrylamide, N-tert-butyl (meth) acrylamide, N-hexyl (meth) acrylamide and the like. Similarly, specific examples of N-substituted (meth) acrylamide in which both Q ₂ and Q ₃ are alkyl groups include N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide and the like.

Similarly, as specific examples of N-substituted (meth) acrylamide in which Q ₂ is a hydrogen atom and Q ₃ is an alkyl group having a hydroxyl group, N-hydroxymethyl (meth) acrylamide, N- (2-hydroxyethyl) (Meth) acrylamide, N- (2-hydroxypropyl) (meth) acrylamide and the like. Similarly, as a specific example of N-substituted (meth) acrylamide in which Q ₂ is a hydrogen atom and Q ₃ is an alkyl group having an amino group, N- [2- (N, N-dimethylamino) ethyl] (Meth) acrylamide, N- [2- (N, N-diethylamino) ethyl] (meth) acrylamide, N- [3- (N, N-dimethylamino) propyl] (meth) acrylamide, N- [1-methyl -1- (N, N-dimethylamino) ethyl] (meth) acrylamide.

Further, as a specific example of N-substituted (meth) acrylamide in which Q ₂ and Q ₃ in formula (I) are combined to form a 5-membered ring or a 6-membered ring with the nitrogen atom to which they are bonded, There are N-acryloylpyrrolidine, 3-acryloyl-2-oxazolidinone, 4-acryloylmorpholine, N-acryloylpiperidine, N-methacryloylpiperidine and the like.

  Among the N-substituted (meth) acrylamides described above, N-hydroxyalkyl (meth) acrylamide, N, N-dimethylacrylamide, N-hydroxymethylacrylamide and N- (2-hydroxyethyl) acrylamide, N, N-dialkyl (meth) acrylamide, such as N, N-diethylacrylamide, is preferred, and N- (2-hydroxyethyl) acrylamide or N, N-dimethylacrylamide is particularly preferred. When the active energy ray-curable resin composition containing the compound comes into contact with the first retardation plate having the (meth) acrylic resin layer on the outermost surface, the (meth) acrylic resin layer In order to make it melt | dissolve or swell, the adhesive force of the adhesive layer after hardening and the (meth) acrylic-type resin layer which comprises a 1st phase difference plate can be improved.

  In addition, N-alkyl (meth) acrylamide having a long-chain alkyl such as N-dodecyl (meth) acrylamide, N- (methoxymethyl) acrylamide, N- (ethoxymethyl) acrylamide, N- (propoxymethyl) acrylamide N- (alkoxyalkyl) (meth) acrylamide, such as N- (butoxymethyl) acrylamide, may also be used as the N-substituted (meth) acrylamide constituting the curable component of the active energy ray-curable resin composition. it can.

<Compound having (meth) acryloyloxy group>
The compound having a (meth) acryloyloxy group in the molecule, which is another curable component of the active energy ray-curable resin composition, is a variety of compounds having at least one (meth) acryloyloxy group in the molecule. Hereinafter, it may be simply referred to as “(meth) acrylate”. Specifically, it is obtained by reacting at least one (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule or a compound having a functional group, and (meth) acryloyloxy in the molecule. A (meth) acrylate oligomer having at least two groups corresponds to this.

  The (meth) acrylate monomer includes a monofunctional (meth) acrylate monomer having one (meth) acryloyloxy group in the molecule, a bifunctional (meth) acrylate monomer having two (meth) acryloyloxy groups in the molecule, And a trifunctional or higher polyfunctional (meth) acrylate monomer having three or more (meth) acryloyloxy groups in the molecule.

  The monofunctional (meth) acrylate monomer can be, for example, a compound represented by the following formula (II).

In the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents an alcohol residue. The alcohol residue represented by R ₂ is typically an aliphatic hydrocarbon residue having 1 to 12 carbon atoms and an alicyclic group having 5 to 12 carbon atoms which may have an oxygen atom as a ring member. A hydrocarbon residue, or an araliphatic hydrocarbon residue having 7 to 12 carbon atoms, which may have a substituent selected from a hydroxyl group, an alkoxy group, an aryloxy group, and an amino group; In the case of a group hydrocarbon residue, it may have an ether bond (—O—) in the middle. Here, when the alicyclic hydrocarbon residue has a bond that directly connects to the oxygen atom of the (meth) acryloyloxy group in formula (II) from the carbon atom that is a ring member of the alicyclic hydrocarbon. In addition, the case where the above-mentioned bond is taken out from the carbon atom of the aliphatic hydrocarbon connected to the alicyclic hydrocarbon is also included.

The alkoxy group that can be a substituent of R ₂ can have about 1 to 6 carbon atoms, and examples thereof include methoxy, ethoxy, propoxy, and butoxy. Similarly, the aryloxy group can have about 6 to 12 carbon atoms, and is typically phenoxy. Similarly, the amino group may be a substituted amino group such as N-alkylamino and N, N-dialkylamino in addition to unsubstituted amino (NH ₂ −).

In the above formula (II), when R ₂ is an aliphatic hydrocarbon residue having 1 to 12 carbon atoms, typically an alkyl group corresponds to the aliphatic hydrocarbon residue, and the alkyl group has a carbon number. If it is 3 or more, it may be linear or branched. When R ₂ is an alkyl group, specific examples of the alkyl (meth) acrylate represented by the above formula (II) corresponding thereto include methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, Examples include butyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and isononyl (meth) acrylate. When R ₂ is an alkyl group, the number of carbon atoms is preferably about 1 to 6.

When R ₂ is an alkyl group having a hydroxyl group, specific examples of the monofunctional (meth) acrylate represented by the formula (II) corresponding thereto include 2-hydroxyethyl (meth) acrylate, 2- or 3- Hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (Meth) acrylate and the like.

When R ₂ is an alkyl group having an alkoxy group, specific examples of the monofunctional (meth) acrylate represented by the above formula (II) include ethyl carbitol (meth) acrylate. When R ₂ is an alkyl group having an aryloxy group, specific examples of the monofunctional (meth) acrylate represented by the formula (II) corresponding thereto include 2-phenoxyethyl (meth) acrylate, phenoxypolyethylene glycol (Meth) acrylate and the like. When R ₂ is an alkyl group having an amino group, specific examples of the monofunctional (meth) acrylate represented by the formula (II) corresponding thereto include 2- (N, N-dimethylamino) ethyl (meta ) Acrylate.

When R ₂ is an alicyclic hydrocarbon residue having 5 to 12 carbon atoms which may have an oxygen atom as a ring member, the corresponding monofunctional (meth) acrylate represented by the formula (II) Specific examples include (meth) acrylates of terpene alcohol such as isobornyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, cyclohexanedimethanol mono (meth) acrylate, dicyclopentanyl (meth) acrylate, di- Examples include cyclopentenyl (meth) acrylate.

When R ₂ is an araliphatic hydrocarbon residue, specific examples of the monofunctional (meth) acrylate represented by the above formula (II) include benzyl (meth) acrylate.

The ethyl carbitol (meth) acrylate and phenoxy polyethylene glycol (meth) acrylate listed above are aliphatic hydrocarbon residues in which R ₂ in the formula (II) has an ether bond (—O—) in the middle. It corresponds to an example.

  Further, (meth) acrylate having a carboxyl group at the alcohol site can also be used as monofunctional methacrylate. Specific examples of the monofunctional (meth) acrylate having a carboxyl group at the alcohol site include 2-carboxyethyl (meth) acrylate, 1- [2- (meth) acryloyloxyethyl] phthalic acid, 1- [2- ( Meth) acryloyloxyethyl] hexahydrophthalic acid, 1- [2- (meth) acryloyloxyethyl] succinic acid, 4- [2- (meth) acryloyloxyethyl] trimellitic acid, and the like.

Among the monofunctional (meth) acrylates described above, in Formula (II), R ₂ may be a (meth) acrylate having an alkyl group or a hydroxyalkyl group, and R ₂ may have an oxygen atom as a ring member. In particular, (meth) acrylate which is an alicyclic hydrocarbon residue which may have a hydroxyl group is particularly preferable. These monomers are cured to dissolve or swell the cycloolefin resin when the active energy ray-curable resin composition containing the monomer comes into contact with the cycloolefin resin film constituting the second retardation plate. Adhesion between the subsequent adhesive layer and the second retardation plate can be increased.

  Next, a polyfunctional (meth) acrylate having a plurality of (meth) acryloyloxy groups in the molecule will be described. As described above, the polyfunctional (meth) acrylate has a bifunctional (meth) acrylate monomer having two (meth) acryloyloxy groups in the molecule and three or more (meth) acryloyloxy groups in the molecule. There are a polyfunctional (meth) acrylate monomer having three or more functional groups, a (meth) acrylate oligomer having at least two (meth) acryloyloxy groups in the molecule obtained by reacting two or more kinds of compounds having functional groups. These monomers and oligomers will be specifically described.

  Typical examples of the bifunctional (meth) acrylate monomer include alkylene glycol di (meth) acrylates, polyoxyalkylene glycol di (meth) acrylates, halogen-substituted alkylene glycol di (meth) acrylates, aliphatic polyols Di (meth) acrylates, di (meth) acrylates of hydrogenated dicyclopentadiene or tricyclodecane dialkanol, di (meth) acrylates of dioxane glycol or dioxane dialkanol, alkylene oxide adducts of bisphenol A or bisphenol F Di (meth) acrylates, epoxydi (meth) acrylates of bisphenol A or bisphenol F, and the like.

  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, ditri Methylolpropane di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyester Lenglycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, di (meth) acrylate of hydroxypivalic acid neopentyl glycol ester, 2,2-bis [4- {2 -(2- (meth) acryloyloxyethoxy) ethoxy} phenyl] propane, 2,2-bis [4- {2- (2- (meth) acryloyloxyethoxy) ethoxy} cyclohexyl] propane, hydrogenated dicyclopentadi Enildi (meth) acrylate, tricyclodecane dimethanol di (meth) acrylate, 1,3-dioxane-2,5-diyldi (meth) acrylate [also known as dioxane glycol di (meth) acrylate], hydroxypivalaldehyde Trimethylol 1. Di (meth) acrylate of acetalized product with propane [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane], 1,3 And di (meth) acrylate of 5-tris (2-hydroxyethyl) isocyanurate.

  A typical trifunctional or higher polyfunctional (meth) acrylate monomer is a poly (meth) acrylate of a trivalent or higher aliphatic polyol. Specific examples include glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, penta Examples include erythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, and dipentaerythritol hexa (meth) acrylate.

  In addition, poly (meth) acrylates of trivalent or higher-valent halogen-substituted polyols, tri (meth) acrylates of alkylene oxide adducts of glycerol, tri (meth) acrylates of alkylene oxide adducts of trimethylolpropane, 1,1,1 -Tris [2- {2- (meth) acryloyloxyethoxy} ethoxy] propane, 1,3,5-tris [2- (meth) acryloyloxyethyl] isocyanurate can also be a polyfunctional (meth) acrylate monomer .

  On the other hand, (meth) acrylate oligomers include urethane (meth) acrylate oligomers, polyester (meth) acrylate oligomers, and epoxy (meth) acrylate oligomers.

  The urethane (meth) acrylate oligomer refers to a compound having at least two (meth) acryloyloxy groups in the molecule and a urethane bond (—NHCOO—). Specifically, a urethanization reaction product of a hydroxyl group-containing (meth) acrylate monomer and a polyisocyanate each having one hydroxyl group and at least one (meth) acryloyloxy group in the molecule, or a polyol is a polyisocyanate. Urethane reaction product of a terminal isocyanato group-containing urethane compound obtained by reacting with a hydroxyl group-containing (meth) acrylate monomer each having one hydroxyl group and at least one (meth) acryloyloxy group in the molecule, etc. It can be.

  Specific 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-Phenoxypropyl (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol penta (meth) acrylate and the like.

  Specific examples of the polyisocyanate subjected to the urethanation reaction with such a hydroxyl group-containing (meth) acrylate monomer include hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and aromatic. Compounds obtained by hydrogenating diisocyanates, for example, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, triphenylmethane triisocyanate, dibenzylbenzene triisocyanate, obtained by increasing the amount of these diisocyanates Polyisocyanate etc. are mentioned.

  Moreover, as polyols for manufacturing a terminal isocyanate group containing urethane compound by reaction with polyisocyanate, polyester polyol, polyether polyol, etc. other than an aliphatic or alicyclic polyol can be used. Specific examples of the aliphatic or alicyclic polyol include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, trimethylol. Examples include methylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutyric acid, glycerin, and hydrogenated bisphenol A.

  The polyester polyol is a compound obtained by subjecting the above-described polyols to a dehydration condensation reaction of a polybasic carboxylic acid or an anhydride thereof. Specific examples of the polybasic carboxylic acid and its anhydride are listed as “(anhydrous)” on what may be an anhydride, and (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, There are (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, hexahydro (anhydrous) phthalic acid and the like.

  The polyether polyol may be a polyoxyalkylene-modified polyol obtained by reacting an alkylene oxide with the above-described polyols or bisphenols, in addition to the polyalkylene glycol.

  The polyester (meth) acrylate oligomer refers to a compound having at least two (meth) acryloyloxy groups in the molecule and an ester bond. Specifically, it can be obtained by dehydration condensation reaction of (meth) acrylic acid, polybasic carboxylic acid or anhydride thereof, and polyol. Specific examples of the polybasic carboxylic acid or anhydride thereof used in the dehydration condensation reaction are listed as “(anhydrous)” on what may be an anhydride, and (anhydrous) succinic acid, adipic acid, (Anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, hexahydro (anhydrous) phthalic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid and the like. Specific examples of the polyol used in the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, trimethylol. Examples include methylolpropane, ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutyric acid, glycerin, and hydrogenated bisphenol A.

  The epoxy (meth) acrylate oligomer means one obtained by addition reaction of polyglycidyl ether and (meth) acrylic acid, and also has at least two (meth) acryloyloxy groups in the molecule. Specific examples of the polyglycidyl ether used in this 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. and so on.

  In the present invention, the compound having a (meth) acryloyloxy group in the molecule is, from one viewpoint, a compound having one (meth) acryloyloxy group in the molecule, that is, a monofunctional (meth) acrylate, and It is preferable to contain both a compound having two or more (meth) acryloyloxy groups in the molecule, that is, a polyfunctional (meth) acrylate. As described above, the monofunctional (meth) acrylate is effective for enhancing the adhesion with the cycloolefin-based resin film constituting the second retardation plate. Moreover, polyfunctional (meth) acrylate is effective in increasing the cohesive strength of the adhesive. Therefore, by using these two types of (meth) acrylates in combination, the adhesive strength with the cycloolefin resin film can be increased while increasing the cohesive strength of the adhesive. On the other hand, the N-substituted (meth) acrylamide described above bears the adhesive force with the (meth) acrylic resin layer constituting the outermost surface of the first retardation plate. The mixing ratio of monofunctional (meth) acrylate and polyfunctional (meth) acrylate can be appropriately set depending on the type of each compound, the type of (meth) acrylic resin and cycloolefin resin that are adherends, etc. Good. In particular, polyfunctional (meth) acrylates may exhibit the above-described cohesive strength improving effect even in a small amount depending on the type, so that polyfunctional (meth) acrylate is 1 per 100 parts by weight of monofunctional (meth) acrylate. It is preferable to select from a range of about 200 parts by weight. The weight ratio of monofunctional (meth) acrylate: polyfunctional (meth) acrylate is, for example, about 100: 1 to about 50, more preferably about 100: 1 to 10 as in Example 9 described later. In some cases, as in Examples 10 to 22 described later, it is appropriate that the ratio is about 100: 10 to 200, and further about 100: 50 to 200.

<Quantitative ratio of N-substituted (meth) acrylamide and (meth) acrylate>
In the present invention, the N-substituted (meth) acrylamide and (meth) acrylate described above are used in combination as a curable component in the active energy ray-curable resin composition. And the proportion of N-substituted (meth) acrylamide based on the total amount of the curable component, including other compounds that are cured by irradiation with active energy rays, and 5 to 80% by weight, and It is preferable that the ratio of (meth) acrylate is 20 to 95% by weight.

  If the proportion of N-substituted (meth) acrylamide in the entire curable component is too small and the proportion of (meth) acrylate is too large, adhesion to the (meth) acrylic resin layer that is the adhesive surface of the first retardation plate Power tends to decline. On the other hand, when the proportion of N-substituted (meth) acrylamide is too large and the proportion of (meth) acrylate is too small, the adhesive force to the cycloolefin resin film as the second retardation plate tends to be lowered. In the case where only a monofunctional (meth) acrylate represented by the compound represented by the formula (II) is used as a compound having a (meth) acryloyloxy group in the molecule, especially when importance is attached to the adhesive force, a curable component Based on the total amount, N-substituted (meth) acrylamide is 60 to 80% by weight, further 70 to 80% by weight, and (meth) acrylate is 20 to 40% by weight, further 20 to 30% by weight. You can also.

  In the present invention, the first phase difference plate having the (meth) acrylic resin layer on the outermost surface (adhesion surface) and the second phase difference plate made of a cycloolefin resin film are bonded, so that an adhesive is obtained. The curable component constituting the active energy ray-curable resin composition preferably includes a compound that dissolves or swells the (meth) acrylic resin and a compound that dissolves or swells the cycloolefin-based resin. As described above, N-substituted (meth) acrylamide tends to dissolve or swell the (meth) acrylic resin, and (meth) acrylate tends to dissolve or swell the cycloolefin-based resin.

<Photoradical polymerization initiator>
The active energy ray-curable resin composition contains the above-described N-substituted (meth) acrylamide and (meth) acrylate as curable components, both of which are radically polymerizable compounds. It is preferable to mix a radical photopolymerization initiator. The radical photopolymerization initiator is not particularly limited as long as it can initiate the polymerization of the radical polymerizable compound by irradiation with active energy rays, and a conventionally known one can be used. Specific examples of the radical photopolymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1 Acetophenone based initiators such as [4- (methylthio) phenyl-2-morpholinopropan-1-one and 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone, 4-chlorobenzophenone and 4 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; others, xanthone, fluorenone, camphor Down, benzaldehyde, there is such as anthraquinone.

  The compounding quantity of radical photopolymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of radically polymerizable compounds containing N-substituted (meth) acrylamide and (meth) acrylate, Preferably it is 1- 6 parts by weight. When the amount of the radical photopolymerization initiator is small, curing is insufficient and mechanical strength and adhesiveness tend to be lowered. On the other hand, if the amount of radical photopolymerization initiator is too large, the amount of active energy ray-curable compound in the curable resin composition will be relatively small, and the durability performance of the resulting composite retardation plate may be reduced. There is.

<Other optional components that can be incorporated into the curable resin composition>
The active energy ray-curable resin composition can further contain a photosensitizer as necessary. By incorporating a photosensitizer, the reactivity of radical polymerization is improved, and the mechanical strength and adhesiveness of the adhesive layer can be improved. The photosensitizer may be a compound having a maximum absorption at a wavelength longer than 380 nm. For example, a carbonyl compound, an organic sulfur compound, a persulfide, a redox compound, an azo and diazo compound, a halogen compound, an anthracene compound, Examples include photoreducible dyes. Examples of carbonyl compounds that can be photosensitizers include: benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether and 2,2-dimethoxy-2-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, o-benzoyl Benzophenone compounds such as methyl benzoate, 4,4'-bis (dimethylamino) benzophenone and 4,4'-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; Anthraquinone derivatives such as chloroanthraquinone and 2-methylanthraquinone; and acridone derivatives such as N-methylacridone and N-butylacridone. Anthracene compounds preferably have an alkoxy group at the 9th and 10th positions of anthracene, and examples of anthracene compounds that can be used as photosensitizers include 9,10-dipropoxyanthracene, 2-methyl-9, 10-dipropoxyanthracene, 2-ethyl-9,10-dipropoxyanthracene, 9,10-dibutoxyanthracene, 2-methyl-9,10-dibutoxyanthracene, 2-ethyl-9,10-dibutoxyanthracene, etc. There is. These photosensitizers may be used alone or in combination of two or more. When mix | blending a photosensitizer, the quantity is about 0.1-20 weight part normally by making the whole active energy ray-curable compound into 100 weight part.

  Moreover, the active energy ray-curable resin composition may contain an antistatic agent for imparting antistatic performance. Various known antistatic agents can be used. For example, a cationic surfactant, an anionic surfactant, a nonionic surfactant, an ionic compound having an organic cation other than the cationic surfactant, an ionic compound having an organic anion other than the anionic surfactant, and conductivity Inorganic particles, conductive polymers, and the like can be used. The blending ratio of these antistatic agents is appropriately determined according to the desired characteristics, but is usually about 0.1 to 10 parts by weight with 100 parts by weight of the entire active energy ray-curable compound.

  The active energy ray-curable resin composition can also contain a known polymer additive usually used for polymers. For example, primary antioxidants such as phenols and amines, sulfur secondary antioxidants, hindered amine light stabilizers (HALS), benzophenone, benzotriazole, benzoate UV absorbers, etc. .

  A leveling agent can also be mix | blended with an active energy ray curable resin composition. When the curable resin composition is applied to a first retardation plate having a (meth) acrylic resin layer on the outermost surface or a second retardation plate made of a cycloolefin resin film, the paintability is poor. The wettability can be improved by adding a leveling agent. As the leveling agent, various compounds having a leveling effect such as silicone-based, fluorine-based, polyether-based, acrylic copolymer-based, and titanate-based can be used. The mixing ratio of the leveling agent is about 0.01 to 1 part by weight with respect to 100 parts by weight of the active energy ray-curable compound contained in the curable resin composition.

  Furthermore, the active energy ray-curable resin composition may contain a solvent as necessary. The solvent is appropriately selected in consideration of 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 butanol; acetone, Ketones such as 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; halogenated carbonization such as methylene chloride and chloroform Hydrogen etc. are mentioned. The blending ratio of the solvent is appropriately determined from the viewpoints of viscosity adjustment according to processing purposes such as film formability and the optimum viscosity range in the coating method to be employed.

[Adhesion between first retardation plate and second retardation plate]
The active energy ray-curable resin composition forming the adhesive layer 31 is applied to one of the attachment surfaces of the first retardation plate 10 and the second retardation plate 18, and the other position is applied thereto. Laminate phase difference plates. For the application of the active energy ray-curable resin composition, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used.

The light source used for the irradiation of the active energy ray is not particularly limited, and has a light emission distribution at a wavelength of 400 nm or less. A metal halide lamp or the like can be used. The light irradiation intensity to the active energy ray-curable resin composition varies depending on the composition, but it is preferable that the irradiation intensity in the wavelength region effective for activating the polymerization initiator is 10 to 2500 mW / cm ^2. . If the light irradiation intensity to the active energy ray-curable resin composition is too small, the time required for the reaction to proceed sufficiently increases, and conversely, if it is too large, the heat and active energy rays radiated from the lamp. The heat generated during the polymerization of the curable resin composition may cause yellowing of the active energy ray-curable resin composition or deterioration of a film to be attached. The light irradiation time to the active energy ray curable resin composition is also controlled for each composition and is not particularly limited, but the integrated light amount expressed as the product of irradiation intensity and irradiation time is 10 to 2, It is preferable to set it to be 500 mJ / cm ² . If the integrated light amount to the active energy ray-curable resin composition is too small, the generation of active species derived from the polymerization initiator is not sufficient, and the resulting adhesive layer may be insufficiently cured. On the other hand, if the integrated light quantity is too large, the irradiation time becomes very long, which is disadvantageous for improving productivity.

  The adhesive layer obtained by curing the active energy ray-curable resin composition described above has a thickness of 10 μm or less. When the thickness of the adhesive layer exceeds 10 μm, the effect of thinning becomes small. The thickness of the adhesive layer is preferably 0.1 μm or more from the viewpoint of adhesiveness. The thickness is more preferably 5 μm or less, and further preferably 3 μm or less.

  The adhesive layer preferably has a glass transition temperature in the range of -20 to 80 ° C. The glass transition temperature of the adhesive layer is more preferably −15 ° C. or higher, more preferably −10 ° C. or higher, more preferably 70 ° C. or lower, further 60 ° C. or lower, and particularly preferably 50 ° C. or lower. If the glass transition temperature of the adhesive layer is too low, the cohesive force of the adhesive layer becomes small, and cohesive failure of the adhesive layer easily occurs. On the other hand, if the glass transition temperature of the adhesive layer is too high, the adhesion to the first retardation plate and the second retardation plate tends to decrease. The glass transition temperature can be measured by a differential scanning calorimeter (DSC).

[Composite polarizing plate]
The composite retardation plate 20 of the present invention whose layer configuration is shown in FIG. 1 can be combined with a polarizing plate to form a composite polarizing plate. An example of a preferable layer structure of the composite polarizing plate according to the present invention is shown in a schematic sectional view in FIG. As shown in this figure, a protective film 44 made of a thermoplastic resin is laminated on one surface of the polarizing film 42 via a second adhesive layer 32, and a third film is formed on the other surface of the polarizing film 42. The composite retardation plate 20 described above with reference to FIG. 1 is laminated on the second retardation plate 18 side made of the cycloolefin-based resin film via the adhesive layer 33, and the composite polarizing plate 50 is formed. Composed. The surface of the composite retardation plate 20 opposite to the surface bonded to the polarizing film 42 is usually provided with an adhesive layer 46 for bonding to another member such as a liquid crystal cell, and on the outer side thereof, the other member. A separator 48 that temporarily protects the surface of the pressure-sensitive adhesive layer 46 until it is bonded to is provided. In FIG. 2, in order to make the relationship between the layers easy to understand, some layers are shown apart from each other, but in actuality, adjacent layers are in contact with each other and closely bonded. Hereinafter, although each member which comprises the composite polarizing plate 50 is demonstrated in detail, since the composite phase difference plate 20 and each member which comprises it are as having demonstrated above with reference to FIG. 1, these description is abbreviate | omitted. To do.

[Polarized film]
Specifically, the polarizing film 42 is a film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin film. By performing uniaxial stretching either before, during or after adsorption of the dichroic dye, the dichroic dye in the polyvinyl alcohol-based resin film can be oriented in the stretching direction. The polyvinyl alcohol resin can be obtained by saponifying a polyvinyl acetate resin. Polyvinyl acetate resins include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith, such as ethylene-vinyl acetate copolymers. Etc. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins including ethylene, vinyl ethers, and acrylamides having an ammonium group.

  The saponification degree of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified, for example, polyvinyl formal, polyvinyl acetal, polyvinyl butyral and the like modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually in the range of 1,000 to 10,000, preferably in the range of 1,500 to 5,000.

  A film obtained by forming such a polyvinyl alcohol resin is used as a raw film of a polarizing film. The method for forming the polyvinyl alcohol-based resin is not particularly limited, and can be formed by a conventionally known appropriate method. Although the film thickness of the raw film which consists of polyvinyl alcohol-type resin is not specifically limited, For example, it is about 10-150 micrometers.

  A polarizing film usually includes a process of dyeing a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye (dyeing process), and a polyvinyl alcohol resin film on which the dichroic dye is adsorbed. It is manufactured through a step of treating with an acid aqueous solution (boric acid treatment step) and a step of washing with water after the treatment with the boric acid aqueous solution (water washing treatment step).

  Although uniaxial stretching is also performed, the uniaxial stretching of the polyvinyl alcohol-based resin film may be performed before the dyeing process, may be performed during the dyeing process, or may be performed after the dyeing process. Also good. When uniaxial stretching is performed after the dyeing treatment step, this uniaxial stretching may be performed before the boric acid treatment step or during the boric acid treatment step. Of course, it is also possible to perform uniaxial stretching in these plural stages. Uniaxial stretching may be performed by a method of passing a film between spaced rolls having different peripheral speeds, or by a method of sandwiching the film with 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 dyeing process is performed, for example, by immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a dichroic dye. Specifically, iodine or a dichroic organic dye is used as the dichroic dye. The dichroic organic dyes include dichroic direct dyes composed of disazo compounds such as C.I. DIRECT RED 39, and dichroic direct dyes composed of compounds such as trisazo and tetrakisazo. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol resin film by dipping it in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. . When iodine is used as the dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 20 to 1,800 seconds. is there.

On the other hand, when a dichroic organic dye is used as the dichroic dye, usually, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic organic dye is employed. The content of the dichroic organic dye in this aqueous solution is usually 1 × 10 ⁻⁴ to 10 parts by weight, preferably 1 × 10 ⁻³ to 1 part by weight, more preferably 1 × 10 ⁻³ per 100 parts by weight of water. ˜1 × 10 ⁻² parts by weight. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. When a dichroic organic dye is used as the dichroic dye, the temperature of the aqueous dye solution used for dyeing is usually 20 to 80 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 10 to 10 ° C. 1,800 seconds.

  The boric acid treatment step is performed by immersing a polyvinyl alcohol-based resin film dyed with a dichroic dye in an aqueous boric acid solution. The boric acid content in the boric acid aqueous solution is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye in the dyeing process described above, the boric acid aqueous solution used in this process preferably contains potassium iodide. In this case, the content of potassium iodide in the boric acid aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid aqueous solution is usually 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., more preferably 60 to 80 ° C.

  In the subsequent washing process, the polyvinyl alcohol resin film after the boric acid treatment described above is washed with water, for example, by immersing it in water. The water temperature in the water washing treatment is usually 5 to 40 ° C., and the immersion time is usually 1 to 120 seconds. After the water washing treatment, usually a drying treatment is performed to obtain a polarizing film. The drying process can be performed using, for example, a hot air dryer or a far infrared heater. The temperature of a drying process is 30-100 degreeC normally, Preferably it is 50-80 degreeC. The time for the drying treatment is usually 60 to 600 seconds, preferably 120 to 600 seconds.

  As described above, it is possible to produce a polarizing film in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol resin film. The thickness of the polarizing film can be about 5 to 40 μm.

[Protective film made of thermoplastic resin]
As described above, the second retardation plate 18 made of a cycloolefin resin film constituting the composite retardation plate 20 is bonded to one surface of the polarizing film 42, and the opposite surface of the polarizing film 42 is attached to the other surface. Another protective film 44 made of a thermoplastic resin can be bonded. The protective film 44 is also bonded to the polarizing film 42 through an adhesive. The protective film 44 is, for example, a cellulose acetate resin, polyolefin resin, acrylic resin, polyimide resin, polycarbonate resin, polyester resin, etc. It can be composed of the following materials. Of these, a cellulose acetate-based resin film is preferably used as the protective film 44 from the viewpoints of mass productivity and adhesiveness. A cellulose acetate-based resin film is also preferably used as the protective film 44 from the viewpoint of ease of providing the surface treatment layer and optical characteristics.

  The cellulose acetate-based resin film is a film made of a cellulose portion or a complete acetate ester, and examples thereof include a triacetyl cellulose film and a diacetyl cellulose film. Examples of the cellulose acetate-based resin film include commercially available products such as “Fujitack TD80”, “Fujitack TD80UF” and “Fujitack TD80UZ” sold by Fuji Film Co., Ltd., Konica Minolta Opto Co., Ltd. Commercially available “KC8UX2M”, “KC8UY”, “KC4UEW”, etc. (all are trade names) can be used.

  The polarizing film 42 and the protective film 44 made of a thermoplastic resin are bonded using an appropriate adhesive described later. In order to improve the adhesion between the two, either one or both of the bonding surfaces of the two is improved by plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, saponification treatment, primer treatment, etc. You may perform the surface treatment for making it suitable. When the protective film 44 is composed of a cellulose acetate-based resin film and is attached to the polarizing film 42 using a water-based adhesive described later, as one of the preferable surface treatments applied to the cellulose acetate-based resin film, saponification Processing can be mentioned. The saponification treatment is performed by immersing the film in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide.

  The protective film 44 made of a thermoplastic resin is preferably thin, but if it is too thin, the strength tends to be low and the processability tends to be poor. On the other hand, if it is too thick, the transparency may be reduced or the weight of the composite polarizing plate 50 may be reduced. Tend to grow. From such a viewpoint, the thickness of the protective film 44 is generally 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and preferably 200 μm or less, more preferably 150 μm or less, and even more preferably 100 μm or less. It is.

  The protective film 44 made of a thermoplastic resin is subjected to surface treatment such as anti-glare treatment, hard coat treatment, antistatic treatment, antireflection treatment on the surface opposite to the surface to be attached to the polarizing film 42. Also good.

[Adhesive for pasting polarizing film, protective film and composite retardation plate]
An adhesive is used for adhering the polarizing film 42 and the protective film 44 made of a thermoplastic resin and adhering the polarizing film 42 and the second retardation plate 18 constituting the composite retardation plate 20. Thereby, as shown in FIG. 2, the second adhesive layer 32 is provided between the polarizing film 42 and the protective film 44, and the third adhesive layer is provided between the polarizing film and the second retardation plate 18. 33 are formed respectively. The adhesive used for this purpose is only required to exhibit an adhesive force with respect to both, and includes, for example, an aqueous adhesive in which an adhesive component is dissolved or dispersed in water or an active energy ray-curable compound. A curable adhesive is mentioned. Considering that the surface of the polarizing film 42 is hydrophilic, an aqueous adhesive in which an adhesive component is dissolved or dispersed in water is preferable. The water-based adhesive is also preferable from the viewpoint of thinning the cured adhesive layer. As the main component of the water-based adhesive, polyvinyl alcohol resin, urethane resin, or the like can be used. In addition, although the adhesive agent which comprises the 2nd adhesive bond layer 32 and the 3rd adhesive bond layer 33 may be the same or different, it is better to use the same thing if moderate adhesiveness is obtained, This is advantageous from the viewpoint of work efficiency.

  When a polyvinyl alcohol resin is used as the main component of the aqueous adhesive, the polyvinyl alcohol resin can be obtained by saponifying a polyvinyl acetate resin. The polyvinyl acetate resin may be a copolymer of vinyl acetate, which is a homopolymer of vinyl acetate, or a copolymer of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and acrylamides having an ammonium group. The polyvinyl alcohol resin used for the adhesive preferably has an appropriate degree of polymerization. For example, when the aqueous solution has a concentration of 4% by weight, the viscosity is in the range of 4 to 50 mPa · sec, and further 6 More preferably, it is in the range of ˜30 mPa · sec.

  In general, the saponification degree of the polyvinyl alcohol resin used for the adhesive is preferably 80 mol% or more, and more preferably 90 mol% or more. If the degree of saponification of the polyvinyl alcohol resin used for the adhesive is low, the water resistance of the resulting adhesive layer tends to be insufficient.

  For the adhesive, a modified polyvinyl alcohol-based resin is preferably used. Suitable modified polyvinyl alcohol resins include acetoacetyl group-modified polyvinyl alcohol resins, anion-modified polyvinyl alcohol resins, and cation-modified polyvinyl alcohol resins. If such a modified polyvinyl alcohol resin is used, the effect of improving the water resistance of the adhesive layer can be easily obtained.

The acetoacetyl group-modified polyvinyl alcohol resin has an acetoacetyl group (CH ₃ COCH ₂ CO—) in addition to the hydroxyl group constituting the polyvinyl alcohol skeleton, and other acyl groups such as an acetyl group. You may have. This acetoacetyl group typically exists in a state in which a hydrogen atom of a hydroxyl group constituting polyvinyl alcohol is substituted. An acetoacetyl group-modified polyvinyl alcohol resin can be produced, for example, by a method of reacting polyvinyl alcohol with diketene. The acetoacetyl group-modified polyvinyl alcohol-based resin has an acetoacetyl group that is a highly reactive functional group, and thus is preferable for improving the durability of the adhesive layer.

  The content of the acetoacetyl group in the polyvinyl alcohol resin modified with acetoacetyl group is not particularly limited as long as it is 0.1 mol% or more. The content of acetoacetyl group as used herein is a value indicating the mole fraction of acetoacetyl groups with respect to the total amount of hydroxyl groups, acetoacetyl groups, and other acyl groups (acetyl groups, etc.) in the polyvinyl alcohol resin as a percentage. And may be referred to as “degree of acetoacetylation”. If the degree of acetoacetylation in the polyvinyl alcohol-based resin is less than 0.1 mol%, the effect of improving the water resistance of the adhesive layer tends to be insufficient. The degree of acetoacetylation in the polyvinyl alcohol resin is preferably about 0.1 to 40 mol%, more preferably 1 to 20 mol%, and particularly preferably 2 to 7 mol%. When the degree of acetoacetylation exceeds 40 mol%, the effect of improving water resistance tends to be small.

  The anion-modified polyvinyl alcohol resin has an anionic group, typically a carboxyl group (—COOH) or a salt thereof in addition to the hydroxyl group constituting the polyvinyl alcohol skeleton, and other acyl groups, for example, It may have an acetyl group or the like. This anion-modified polyvinyl alcohol resin can be produced, for example, by a method in which an unsaturated monomer having an anionic group (typically a carboxyl group) is copolymerized with vinyl acetate and then saponified. . On the other hand, a cation-modified polyvinyl alcohol resin contains a cationic group, typically a tertiary amino group or a quaternary ammonium group, in addition to the hydroxyl group constituting the polyvinyl alcohol skeleton. It may have a group such as an acetyl group. This cation-modified polyvinyl alcohol resin is obtained by, for example, copolymerizing an unsaturated monomer having a cationic group (typically a tertiary amino group or a quaternary ammonium group) with vinyl acetate and then saponifying it. It can be manufactured by a method.

  The adhesive used in the present invention may contain two or more kinds of the above-mentioned modified polyvinyl alcohol resins, or an unmodified polyvinyl alcohol resin such as a complete or partially saponified product of polyvinyl acetate. And a modified polyvinyl alcohol-based resin.

  Since the adhesive mainly composed of polyvinyl alcohol resin is used in the form of an aqueous solution, the concentration thereof is in the range of 1 to 20 parts by weight with respect to 100 parts by weight of water. In particular, it is more preferably 1 to 15 parts by weight, more preferably 1 to 10 parts by weight, particularly preferably 2 to 10 parts by weight. If the concentration of the polyvinyl alcohol resin in the aqueous solution is too small, the adhesiveness tends to decrease, whereas if the concentration is too large, the optical properties of the resulting polarizing plate tend to decrease. The water used for the adhesive can be pure water, ultrapure water, tap water, etc., and is not particularly limited. However, from the viewpoint of maintaining the uniformity and transparency of the formed adhesive layer, Water or ultrapure water is preferred. Alcohols such as methanol and ethanol can also be added to the adhesive aqueous solution.

  The polyvinyl alcohol-based resin constituting the adhesive can be used by appropriately selecting from commercially available products. Specifically, for example, polyvinyl alcohol having a high degree of saponification, such as “PVA-117H” sold by Kuraray Co., Ltd. and “Gosenol NH” sold by Nippon Synthetic Chemical Industry Co., Ltd. -20 ", polyvinyl alcohol modified with acetoacetyl group," Gosefimer Z "series sold by Nippon Synthetic Chemical Industry Co., Ltd., anion-modified polyvinyl alcohol, Kuraray Co., Ltd. "KL-318" and "KM-118" sold by KK, "Gosenal T-330" sold by Nippon Synthetic Chemical Industry Co., Ltd., cation-modified polyvinyl alcohol, For example, “CM-318” sold by Kuraray and “Gosefimer K-210” sold by Nippon Synthetic Chemical Industry Co., Ltd. That.

  A water-based adhesive mainly composed of a polyvinyl alcohol resin can contain a crosslinking agent. The crosslinking agent may be any compound containing a functional group having reactivity with the polyvinyl alcohol resin, and those conventionally used in polyvinyl alcohol adhesives can be used without particular limitation. When compounds capable of forming a crosslinking agent are listed by functional group, an isocyanate compound having at least two isocyanato groups (—NCO) in the molecule; an epoxy compound having at least two epoxy groups in the molecule; mono- or di-aldehydes; Organic titanium compounds; inorganic salts of divalent or trivalent metals such as magnesium, calcium, iron, nickel, zinc, and aluminum; metal salts of glyoxylic acid; methylol melamine.

  Specific examples of the isocyanate compound used as the crosslinking agent include tolylene diisocyanate, hydrogenated tolylene diisocyanate, adducts of trimethylolpropane and tolylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, isophorone diisocyanate, and ketoximes thereof. A block thing or a phenol block thing etc. are mentioned.

  Specific examples of the epoxy compound serving as a crosslinking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, di- or tri-glycidyl ether of glycerin, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether. , Diglycidyl aniline, diglycidyl amine, water-soluble polyamide epoxy resin obtained by reacting epichlorohydrin with polyamide polyamine which is a reaction product of polyalkylene polyamine and dicarboxylic acid.

  Specific examples of monoaldehydes that serve as crosslinking agents include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, and specific examples of dialdehydes include glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, Maleic dialdehyde, phthaldialdehyde and the like can be mentioned.

  Various organic titanium compounds that serve as crosslinking agents are sold by Matsumoto Fine Chemical Co., Ltd. Suitable for the present invention from the company's home page (Organic <URL: http://www.m-chem.co.jp/products/products1.html>, retrieved on November 16, 2011) The water-soluble organotitanium compounds used are listed below in the order of their formula, chemical name, and product name.

[(CH ₃ ) ₂ CHO] ₂ Ti [OCH ₂ CH ₂ N (CH ₂ CH ₂ OH) ₂ ] ₂ : Chemical name "Titanium diisopropoxybis (triethanolaminate)", the company's product name “Orgachicks TC-400”,
(HO) ₂ Ti [OCH (CH ₃ ) COO ⁻ ] ₂ (NH ₄ ⁺ ) ₂ : Chemical name “Titanium lactate ammonium salt”, the company's product name “OrgaTix TC-300”,
(HO) ₂ Ti [OCH (CH ₃ ) COOH] ₂ : Chemical name “titanium lactate”, the company name “Orgachix TC-310” and “Orgachix TC-315”.

  The metal salt of glyoxylic acid is preferably an alkali metal salt or an alkaline earth metal salt, and examples thereof include sodium glyoxylate, potassium glyoxylate, magnesium glyoxylate, and calcium glyoxylate.

  Among these crosslinking agents, epoxy compounds including the above-mentioned water-soluble polyamide epoxy resins, aldehydes, methylol melamine, alkali metal or alkaline earth metal salts of glyoxylic acid, and the like are preferably used.

  The crosslinking agent is preferably dissolved in water together with the polyvinyl alcohol resin to form an adhesive. However, since the amount of the crosslinking agent in the aqueous solution may be small as described below, any crosslinking agent having a solubility of, for example, about 0.1% by weight in water can be used. Of course, a compound having a solubility in water of a level generally called water solubility is more suitable as a crosslinking agent used in the present invention.

  The amount of the crosslinking agent is appropriately designed according to the type of the polyvinyl alcohol resin and the like, but is usually about 5 to 60 parts by weight, preferably 10 to 50 parts per 100 parts by weight of the polyvinyl alcohol resin. Parts by weight. When the crosslinking agent is blended within this range, good adhesiveness can be obtained. As described above, in order to improve the durability of the adhesive layer, an acetoacetyl group-modified polyvinyl alcohol-based resin is preferably used. In this case as well, crosslinking is performed with respect to 100 parts by weight of the polyvinyl alcohol-based resin. It is preferable to blend the agent in a proportion of 5 to 60 parts by weight, more preferably 10 to 50 parts by weight. If the amount of the cross-linking agent is too large, the cross-linking reaction of the adhesive proceeds in a short time and the adhesive tends to gel early, making the pot life extremely short and difficult to use industrially. become.

  The adhesive may be blended with conventionally known appropriate additives such as a silane coupling agent, a plasticizer, an antistatic agent, and fine particles as long as the effects of the present invention are not impaired.

  When a urethane resin is used as the main component of the water-based adhesive, an example of a suitable adhesive is a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group. The polyester ionomer type urethane resin here is a urethane resin having a polyester skeleton, into which a small amount of ionic component (hydrophilic component) is introduced. Such an ionomer type urethane resin is suitably used for an aqueous adhesive because it is emulsified directly in water without using an emulsifier to form an emulsion. The use of a polyester ionomer-type urethane resin as an adhesive for a polarizing film and a protective film is, for example, disclosed in JP-A-2005-070140, JP-A-4432487 (= JP-A-2005-181817) and JP-A-2005-208456. It is described in the gazette.

  A curable adhesive containing an active energy ray-curable compound can also be used for adhering the polarizing film 42 to the second retardation plate 18 made of the protective film 44 and / or the cycloolefin resin film. The “active energy ray-curable compound” means a compound that can be cured by irradiation with active energy rays. The active energy ray-curable compound may be cationically polymerizable or radically polymerizable. Examples of the cationic polymerizable compound include an epoxy compound having at least one epoxy group in the molecule, an oxetane compound having at least one oxetane ring in the molecule, and the like. Examples of the radical polymerizable compound include (meth) acrylic compounds having at least one (meth) acryloyloxy group in the molecule.

  The active energy ray-curable compound used for this sticking preferably contains at least an epoxy compound, and in particular, it is favorable between the polarizing film 42 and the second retardation plate 18 made of a cycloolefin-based resin film. It shows adhesion. In addition, the active energy ray-curable adhesive having an epoxy compound as a curable component exhibits good adhesion even between the protective film 44 and the polarizing film 42 when the protective film 44 is composed of a cellulose acetate resin film.

  From the viewpoint of weather resistance, refractive index, cationic polymerizability, and the like, the epoxy compound preferably contains an epoxy compound containing no aromatic ring in the molecule as a main component. As an epoxy compound which does not contain an aromatic ring in a molecule | numerator, the glycidyl ether of the polyol which has an alicyclic ring, an aliphatic epoxy compound, an alicyclic epoxy compound etc. can be illustrated. An epoxy compound suitably used for such an active energy ray-curable adhesive is described in detail in, for example, Japanese Patent No. 4306270 (= Japanese Patent Laid-Open No. 2004-245925), but the outline is also described here. I will do it.

  The glycidyl ether of a polyol having an alicyclic ring is a glycidyl etherification of a nuclear hydrogenated polyhydroxy compound obtained by selectively hydrogenating an aromatic polyol under pressure in the presence of a catalyst. Can be. Examples of the aromatic polyol include bisphenol type compounds such as bisphenol A, bispheel F, and bisphenol S; novolac type resins such as phenol novolac resin, cresol novolac resin, and hydroxybenzaldehyde phenol novolac resin; tetrahydroxydiphenylmethane, Examples thereof include tetrahydroxybenzophenone and polyfunctional compounds such as polyvinylphenol. Glycidyl ether can be obtained by reacting an alicyclic polyol obtained by hydrogenating the aromatic ring of these aromatic polyols with epichlorohydrin. Among these glycidyl ethers of polyols having an alicyclic ring, hydrogenated bisphenol A diglycidyl ether is preferable.

  The aliphatic epoxy compound can be a polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct 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 ether of glycol; Polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to an aliphatic polyhydric alcohol such as ethylene glycol, propylene glycol or glycerin Examples thereof include glycidyl ether.

  An alicyclic epoxy compound is a compound having at least one epoxy group bonded to an alicyclic ring in the molecule. Here, the “epoxy group bonded to the alicyclic ring” means a bridged oxygen atom —O— in the structure represented by the following formula (III), wherein n is an integer of 2 to 5. is there.

A compound in which a group in a form in which one or a plurality of hydrogen atoms in (CH ₂ ) _n in formula (III) are removed is bonded to another chemical structure can be an alicyclic epoxy compound. One or more hydrogen atoms in (CH ₂ ) _n forming the alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group.

  Among the above epoxy compounds, an alicyclic epoxy compound, that is, a compound in which at least one of the epoxy groups is bonded to the alicyclic ring is preferable, and in particular, an oxabicyclohexane ring [the above formula (III) Epoxy compound having an oxabicycloheptane ring (where n = 4 in the above formula (III)) has a high elastic modulus of the cured product and is good between the polarizing film and the protective film. Since adhesiveness is given, it is used more preferably. Specific examples of the alicyclic epoxy compound are listed below. Here, the compound names are given first, and then the chemical formulas corresponding to each are shown, and the same reference numerals are given to the compound names and the chemical formulas corresponding thereto.

A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate,
B: 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate,
C: ethylene bis (3,4-epoxycyclohexanecarboxylate),
D: Bis (3,4-epoxycyclohexylmethyl) adipate,
E: bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate,
F: Diethylene glycol bis (3,4-epoxycyclohexyl methyl ether),
G: ethylene glycol bis (3,4-epoxycyclohexyl methyl ether),
H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro [5.2.2.2.5.2] henicosane,
I: 3- (3,4-epoxycyclohexyl) -8,9-epoxy-1,5-dioxaspiro [5.5] undecane,
J: 4-vinylcyclohexene dioxide,
K: Limonene dioxide
L: bis (2,3-epoxycyclopentyl) ether,
M: Dicyclopentadiene dioxide and the like.

  In the active energy ray-curable adhesive, the epoxy compound may be used alone or in combination of two or more.

  Further, the active energy ray-curable adhesive may contain an oxetane compound in addition to the epoxy compound. By adding an oxetane compound, the viscosity of the adhesive can be lowered and the curing rate can be increased.

  The oxetane compound is a compound having at least one oxetane ring (four-membered ether) 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 And phenol novolac oxetane. The amount of the oxetane compound is usually 50% by weight or less, preferably 10 to 40% by weight, based on the whole active energy ray-curable compound. Oxetane compounds can be easily obtained as commercial products. For example, they are trade names sold by Toagosei Co., Ltd., “Aron Oxetane OXT-101” and “Aron Oxetane OXT-121”. , “Aron Oxetane OXT-211”, “Aron Oxetane OXT-221”, “Aron Oxetane OXT-212”, and the like.

  When the active energy ray-curable adhesive contains a cationically polymerizable compound such as an epoxy compound or an oxetane compound, a photocationic polymerization initiator is usually added to the adhesive. When a cationic photopolymerization initiator is used, it is possible to form an adhesive layer at room temperature, reducing the need to consider the heat resistance of the polarizing film and distortion due to expansion, and sticking the polarizing film and the protective film with good adhesion. Yes. In addition, since the photocationic polymerization initiator acts catalytically with light, the above-mentioned adhesive mixed with it has excellent storage stability and workability.

  The cationic photopolymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, or electron beams, and initiates a polymerization reaction of the cationically polymerizable compound. The photocationic polymerization initiator may be of any type, but specific examples include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-arene complexes, etc. There is.

Examples of the aromatic diazonium salt include the following compounds.
Benzenediazonium hexafluoroantimonate,
Benzenediazonium hexafluorophosphate,
Benzenediazonium hexafluoroborate, etc.

Examples of the aromatic iodonium salt include the following compounds.
Diphenyliodonium tetrakis (pentafluorophenyl) borate,
Diphenyliodonium hexafluorophosphate,
Diphenyliodonium hexafluoroantimonate,
Di (4-nonylphenyl) iodonium hexafluorophosphate and the like.

Examples of the aromatic sulfonium salt include the following compounds.
Triphenylsulfonium hexafluorophosphate,
Triphenylsulfonium hexafluoroantimonate,
Triphenylsulfonium tetrakis (pentafluorophenyl) borate,
4,4'-bis (diphenylsulfonio) diphenyl sulfide bishexafluorophosphate,
4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate,
4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluorophosphate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate,
4-phenylcarbonyl-4'-diphenylsulfonio-diphenyl sulfide hexafluorophosphate,
4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenyl sulfide hexafluoroantimonate,
4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate and the like.

Moreover, as an iron-arene complex, the following compounds are mentioned, for example.
Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,
Cumene-cyclopentadienyl iron (II) hexafluorophosphate,
Xylene-cyclopentadienyl iron (II) tris (trifluoromethylsulfonyl) methanide.

These photocationic polymerization initiators can be easily obtained as commercial products. For example, “Kayarad PCI-220” and “Kayarad PCI-620” sold by Nippon Kayaku Co., Ltd. under the trade names, respectively. "UVI-6990" sold by Union Carbide, "UVACURE 1590" sold by Daicel Cytec, "Adekaoptomer SP-150" sold by ADEKA, and “Adekaoptomer SP-170”, “CI-5102”, “CIT-1370”, “CIT-1682”, “CIP-1866S” sold by Nippon Soda Co., Ltd.,
“CIP-2048S” and “CIP-2064S”, “DPI-101”, “DPI-102”, “DPI-103”, “DPI-105”, “MPI-103” sold by Midori Chemical Co., Ltd. ”,“ MPI-105 ”,“ BBI-101 ”,
“BBI-102”, “BBI-103”, “BBI-105”, “TPS-101”, “TPS-102”, “TPS-103”,
“TPS-105”, “MDS-103”, “MDS-105”, “DTS-102” and “DTS-103”, “PI-2074” sold by Rhodia, and the like.

  These photocationic polymerization initiators may be used alone or in combination of two or more. Among these, in particular, the aromatic sulfonium salt has an ultraviolet absorption property even in a wavelength region of 300 nm or more, so it has excellent curability, gives good mechanical strength, and is good between the polarizing film and the protective film. Since it can give the hardened | cured material which has adhesiveness, it is used preferably.

  The compounding amount of the cationic photopolymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 to 6 parts by weight, based on 100 parts by weight of the total of the cationic polymerizable compounds including the epoxy compound and the oxetane compound. is there. If the amount of the cationic photopolymerization initiator is small, the curing becomes insufficient, and the mechanical strength and the adhesion between the polarizing film and the protective film tend to be lowered. On the other hand, if the amount of the cationic photopolymerization initiator is too large, the amount of ionic substances in the cured product will increase, resulting in an increase in the hygroscopicity of the cured product, which may reduce the durability of the resulting adhesive layer. is there.

  The active energy ray-curable adhesive may contain a radically polymerizable (meth) acrylic compound together with the above-described epoxy compound or together with the epoxy compound and the oxetane compound. By using a (meth) acrylic compound in combination, the effect of increasing the hardness and mechanical strength of the adhesive layer can be expected, and furthermore the adjustment of the viscosity and curing speed of the curable adhesive can be performed more easily. Become. Examples of such a (meth) acrylic compound include the same active energy ray-curable resin compositions that form the adhesive layer described above.

  The adhesive which comprises the 2nd adhesive bond layer 32 and / or the 3rd adhesive bond layer 33 may contain an arbitrary component as needed. As such an optional component, as a component that can be blended in the curable resin composition constituting the adhesive layer 31 for adhering the first retardation plate 10 and the second retardation plate 18 first. The same ones as described can be mentioned.

[Liquid crystal display panel and liquid crystal display device]
The composite polarizing plate 50 of the present invention configured as described above is formed on the surface of the composite retardation plate 20 opposite to the surface attached to the polarizing film 42, that is, on the exposed surface of the first retardation plate 10. The liquid crystal cell is bonded to the liquid crystal cell through the adhesive layer 46 thus formed. This liquid crystal panel is used as a liquid crystal display device in combination with a backlight or the like. In the configuration shown in FIG. 2, the separator 48 provided on the surface of the pressure-sensitive adhesive layer 46 is peeled and removed prior to bonding to the liquid crystal cell. A liquid crystal panel can be configured by disposing the composite polarizing plate 50 of the present invention on both sides of the liquid crystal cell, or a liquid crystal panel can be configured by disposing the composite polarizing plate 50 of the present invention on one side of the liquid crystal cell. . In the latter case, another polarizing plate is generally disposed on the liquid crystal cell surface on which the composite polarizing plate 50 of the present invention is not disposed. The liquid crystal display panel and the liquid crystal display device having such a configuration are particularly effective when the liquid crystal cell is in a transverse electric field (IPS) mode.

  In the above liquid crystal panel and liquid crystal display device, when the composite polarizing plate 50 of the present invention is disposed on one surface of the liquid crystal cell, the transparent protective film on the liquid crystal cell side of the polarizing plate disposed on the other surface is a surface. The inner phase difference Re is preferably 10 nm or less, and the absolute value of the thickness direction retardation Rth is preferably 15 nm or less. More preferably, the in-plane retardation Re is 5 nm or less, and the absolute value of the thickness direction retardation Rth is 10 nm or less.

  Examples of materials used for the transparent protective film having an in-plane retardation Re of 10 nm or less and an absolute value of the thickness direction retardation Rth of 15 nm or less include cellulose resins, cyclic olefin resins, and (meth) acrylic. Resin, polyethylene terephthalate resin, polypropylene resin and the like. A film having a small in-plane and thickness direction retardation may be appropriately selected from films made of these resins.

  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, “%” and “part” representing the content or amount used are based on weight unless otherwise specified. Further, the retardation and Nz coefficient of the film are values measured at a wavelength of 590 nm. First, the manufacture example of the 1st phase difference plate which has a (meth) acrylic-type resin layer is shown.

[Production Example 1] Production of a first retardation plate having a methacrylic resin layer The resin used as the retardation development layer 12 is sold by Nova Chemical Co. under the trade name "Dairark D332" and has a glass transition temperature. A styrene-maleic anhydride copolymer resin having a temperature of 131 ° C. was used. The resin used as the (meth) acrylic resin layers 14 and 15 is used for “Technoloy S001” sold by Sumitomo Chemical Co., Ltd., and approximately 20% of acrylic rubber particles having an average particle diameter of 200 μm. A methacrylic resin having a glass transition temperature of 105 ° C. was used. Then, three-layer coextrusion is performed on both sides of the layer made of styrene-maleic anhydride copolymer resin so that a layer made of methacrylic resin is formed, and a layer made of styrene-maleic anhydride copolymer resin A three-layer resin film having a thickness of 80 μm and a methacrylic resin layer formed on both surfaces of 40 μm was prepared. The resin film having the three-layer structure is stretched so that the retardation developing layer 12 has a thickness of 40 μm, the methacrylic resin layers 14 and 15 each have a thickness of 20 μm, and the total thickness is 80 μm. A plate was made. This retardation plate had an in-plane retardation of 47.3 nm and an Nz coefficient of −1.06.

  Next, the manufacture example of the adhesive agent which consists of a curable resin composition used in order to stick the 1st phase difference plate produced above on the 2nd phase difference plate which consists of a cycloolefin type resin film is shown.

[Production Example 2] Preparation of curable resin composition A N- (2-hydroxyethyl) acrylamide, methyl acrylate, sold by BASF under the trade name "Irgacure 907", and the chemical name is 2-methyl-1 -Photoradical polymerization initiator which is [4- (methylthio) phenyl] -2-morpholinopropan-1-one, and a silicone system sold by Toray Dow Corning Co., Ltd. under the trade name “SH710” A leveling agent was mixed at the following ratio to prepare a curable resin composition A. The above-mentioned “Irgacure 907” is abbreviated as “photo radical polymerization initiator“ Irgacure 907 ””. The above-mentioned “SH710” is abbreviated as “silicone leveling agent“ SH710 ””.

Curable resin composition A
N- (2-hydroxyethyl) acrylamide 80 parts Methyl acrylate 20 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710" 0.2 parts

[Production Examples 3 and 4] Preparation of curable resin compositions B and C The same as in Production Example 2 except that the mixing ratio of N- (2-hydroxyethyl) acrylamide and methyl acrylate was changed as follows. The curable resin compositions B and C were prepared.

Curable resin composition B
N- (2-hydroxyethyl) acrylamide 70 parts Methyl acrylate 30 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710" 0.2 parts

Curable resin composition C
N- (2-hydroxyethyl) acrylamide 60 parts Methyl acrylate 40 parts Photoradical polymerization initiator “Irgacure 907” 3 parts Silicone leveling agent “SH710” 0.2 parts

[Production Example 5] Preparation of curable resin composition X Except that methyl acrylate was not used and the amount of N- (2-hydroxyethyl) acrylamide was 100 parts, it was blended in the same manner as in Production Example 2 and curable. Resin composition X was prepared. The compounding quantity of the curable resin composition X is as follows.

Curable resin composition X
N- (2-hydroxyethyl) acrylamide 100 parts Photoradical polymerization initiator “Irgacure 907” 3 parts Silicone leveling agent “SH710” 0.2 parts

[Production Example 6] Preparation of curable resin composition Y Daicel Chemical Co., Ltd. sells it under the trade name “Celoxide 2021P”, and its chemical name is 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate. An oxetane compound sold by Toagosei Co., Ltd. under the trade name “Aron Oxetane OXT-221”, whose chemical name is bis (3-ethyl-3-oxetanylmethyl) ether, Daicel Cytec 4,4'-bis (diphenylsulfonio) diphenyl sulfide bishexafluorophosphate photocationic polymerization initiator and silicone leveling agent "SH710" sold under the name "UVACURE 1590" The curable resin composition X was prepared by mixing at the following ratio. The above “Celoxide 2021P” is abbreviated as “epoxy compound“ Celoxide 2021P ”” and further abbreviated as “CEL 2021P” in the table. The above “Aron oxetane OXT-221” is abbreviated as “oxetane compound“ Aron oxetane OXT-221 ””, and further abbreviated as “OXT-221” in the table. The above-mentioned “UVACURE 1590” is abbreviated as “photocation polymerization initiator“ UVACURE 1590 ””.

Curable resin composition Y
Epoxy compound “Celoxide 2021P” 75 parts Oxetane compound “Aron Oxetane OXT-221” 25 parts Photocationic polymerization initiator “UVACURE 1590” 5 parts Silicone leveling agent “SH710” 0.2 part

  Next, using the curable resin composition prepared in Production Examples 2 to 6, the second retardation plate made of cycloolefin resin is bonded to the first retardation plate produced in Production Example 1, The Example and comparative example which produced the composite phase difference plate are shown.

[Example 1]
A retardation plate composed of a stretched film of a cycloolefin resin having a thickness of 25 μm (“Zeonor film” sold by Nippon Zeon Co., Ltd., in-plane retardation = 90 nm, thickness direction retardation = 79 nm) Used as a phase difference plate, and after corona treatment is performed on one side thereof, the curable resin composition A produced in Production Example 2 is applied to the corona treatment surface by a coating machine [bar coater manufactured by Daiichi Rika Co., Ltd.] Coated with. Since the film thickness when the curable resin composition was applied varied depending on the viscosity, the number of the bar coater was changed and the film thickness after curing was adjusted to 7 μm. Next, one surface of the first retardation plate produced in Production Example 1 is subjected to corona treatment, and the cycloolefin resin in which the coating film of the curable resin composition A is formed on the corona treatment surface. The film was bonded using a bonding apparatus [“LPA3301” manufactured by Fuji Plastics Co., Ltd.] so that the coating film side became the bonding surface to the first retardation plate. From this cycloolefin resin film side, UV light is applied to this bonded product with an ultraviolet irradiation device with a belt conveyor (the lamp uses a “D bulb” manufactured by Fusion UV Systems Co., Ltd.) so that the integrated light quantity is 250 mJ / cm ^2. Was applied to cure the curable resin composition to produce a composite retardation plate.

[Examples 2 and 3]
A composite retardation plate was produced in the same manner as in Example 1 except that the film thickness after curing of the curable resin composition was adjusted to 5 μm and 3 μm.

[Examples 4 to 6]
Three types with different adhesive layer thicknesses were operated in the same manner as in Examples 1 to 3 except that the curable resin composition B prepared in Production Example 3 was used instead of the curable resin composition A. A composite retardation plate was prepared.

[Examples 7 and 8]
Two types with different adhesive layer thicknesses were prepared in the same manner as in Examples 2 and 3, except that the curable resin composition C prepared in Production Example 4 was used instead of the curable resin composition A. A composite retardation plate was prepared.

[Comparative Examples 1-3]
Three types with different adhesive layer thicknesses were operated in the same manner as in Examples 1 to 3 except that the curable resin composition X prepared in Production Example 5 was used instead of the curable resin composition A. A composite retardation plate was prepared.

[Comparative Examples 4 to 6]
Three types with different adhesive layer thicknesses were operated in the same manner as in Examples 1 to 3 except that the curable resin composition Y prepared in Production Example 6 was used instead of the curable resin composition A. A composite retardation plate was prepared.

[Comparative Example 7]
One side of the same stretched cycloolefin-based resin film having a thickness of 25 μm as used in Example 1 was subjected to corona treatment, and an acrylic pressure-sensitive adhesive sheet having a thickness of 15 μm was bonded thereto. In addition, one side of the first retardation plate produced in Production Example 1 is subjected to corona treatment, and the surface is bonded to the opposite surface of the acrylic adhesive with the stretched cycloolefin resin film. Produced.

[Measurement of Glass Transition Temperature (Tg) of Adhesive Layer]
Two stretched cycloolefin resin films having the same thickness of 25 μm as those used in Example 1 were prepared and used as they were without corona treatment. Then, using a bar coater on one film surface, apply the curable resin compositions A, B, C, X and Y prepared in Production Examples 2 to 6 so that the film thickness after curing is 2 μm. Then, another film is laminated on the coated surface, and ultraviolet light is applied from one surface so that the integrated light amount is 250 mJ / cm ² in accordance with Example 1 to cure the curable resin composition. It was. Next, the film sandwiching the cured product was peeled off, and 5 mg of the cured product was collected, placed in an aluminum presser lid type container, pressed and sealed to prepare a measurement sample.

  Using a differential scanning calorimeter (DSC) “EXSTAR-6000 DSC6220” sold by SII NanoTechnology Co., Ltd., set a container with the above measurement sample in it and purging nitrogen gas The temperature was lowered from 20 ° C. to −60 ° C., held for 1 minute after reaching −60 ° C., then heated from −60 ° C. to 150 ° C. at a rate of 10 ° C./min, and immediately after reaching 150 ° C. The temperature was lowered to 20 ° C. Then, from the DSC curve when the temperature is raised from −60 ° C. to 150 ° C., the midpoint glass transition temperature specified in JIS K 7121-1987 “Plastic Transition Temperature Measurement Method” is obtained, and this is determined as the adhesive layer (curing The glass transition temperature of the product. The results are shown in the “Tg” column of Table 1.

  For the acrylic pressure-sensitive adhesive used in Comparative Example 7, 5 mg of the pressure-sensitive adhesive was collected and placed in a container, and the glass transition temperature was determined by the method described above.

[Adhesive strength evaluation test]
Corona treatment is applied to the cycloolefin resin film surfaces of the composite retardation plates prepared in Examples 1 to 8 and Comparative Examples 1 to 7, and then an acrylic pressure-sensitive adhesive sheet is bonded to the treated surface to provide a pressure-sensitive adhesive. A composite retardation plate was obtained. A test piece having a width of 25 mm and a length of about 200 mm was cut from the obtained composite retardation plate with an adhesive, and the adhesive surface was bonded to soda glass. Then, the pressure was 5 kgf / cm ² and the temperature was 50 in an autoclave. A pressurization treatment was carried out at 20 ° C. for 20 minutes, and further allowed to stand for 1 day in an atmosphere at a temperature of 23 ° C. and a relative humidity of 60%.

  In this state, using a universal tensile tester [“AG-1” manufactured by Shimadzu Corporation], the first phase difference of the three-layer structure at one end in the length direction (one side of 25 mm in width) of the test piece JIS K 6854-1: 1999 "Adhesive-Peeling adhesion strength test method-Part 1" at a crosshead speed (gripping movement speed) of 200 mm / min in an atmosphere of temperature 23 ° C and relative humidity 60% : 90 degree peeling test based on "90 degree peeling" was performed, and the adhesive force between the first retardation plate including the methacrylic resin layer and the second retardation plate made of the cycloolefin resin film was evaluated. . The results are shown in Table 1. In Table 1, “material failure” in the column of “adhesive strength” means that in the above peel test, peel off with the adhesive layer that adheres the first retardation plate and the second retardation plate. It means that the layer of the first retardation plate and / or the second retardation plate is broken.

  As shown in Table 1, by sticking the first retardation plate and the second retardation plate using an adhesive having a mixture of N- (2-hydroxyethyl) acrylate and methyl acrylate as a curable component. The adhesive force can be improved while reducing the film thickness. On the other hand, when the adhesive which uses the mixture of an epoxy compound and an oxetane compound as a sclerosing | hardenable component is used for adhesion | attachment with a 1st phase difference plate and a 2nd phase difference plate (Comparative Examples 4-6), Sufficient adhesion cannot be obtained.

  Next, as a compound having an acryloyloxy group in the molecule, which is one of the curable components constituting the curable resin composition, a compound having one acryloyloxy group in the molecule and two or more acryloyl in the molecule An example in which a curable resin composition is produced using a compound having an oxy group in combination and applied to adhesion between a first retardation plate and a second retardation plate is shown. In the following production examples, the following were used as compounds having an acryloyloxy group in the molecule.

[Compound having one acryloyloxy group in the molecule (monofunctional acrylate)]
4-hydroxybutyl acrylate,
1,4-cyclohexanedimethanol monoacrylate: a product sold under the trade name “CHDMMA” by Nippon Kasei Co., Ltd.
Dicyclopentanyl acrylate: A product sold under the trade name "FA-513S" by Hitachi Chemical.

[Compound having two or more acryloyloxy groups in the molecule (polyfunctional acrylate)]
Trimethylolpropane triacrylate: sold by Shin-Nakamura Chemical Co., Ltd. under the trade name “A-TMPT”
Ethoxylated glycerin triacrylate: sold under the trade name "A-GLY-20E" by Shin-Nakamura Chemical Co., Ltd.
Polyethylene glycol # 600 diacrylate: sold by Shin-Nakamura Chemical Co., Ltd. under the name "A-600"
Bifunctional urethane acrylate “UV-3000B”: sold by Nippon Synthetic Chemical Industry Co., Ltd. under the product name “UV-3000B”
Bifunctional urethane acrylate "UV-3700B": A product sold under the trade name "UV-3700B" by Nippon Synthetic Chemical Industry Co., Ltd.

  In addition, said 4-hydroxybutyl acrylate, 1, 4- cyclohexane dimethanol monoacrylate, dicyclopentanyl acrylate, and a trimethylol propane triacrylate are compounds which have a structure as a name. Ethoxylated glycerin triacrylate [“A-GLY-20E” sold by Shin-Nakamura Chemical Co., Ltd.] has the following structural formula in the manufacturer's catalog.

  Polyethylene glycol # 600 diacrylate ["A-600" sold by Shin-Nakamura Chemical Co., Ltd.] is a compound obtained by converting polyethylene glycol having a molecular weight of about 600 to an acrylate ester. It is shown.

  Also, bifunctional urethane acrylate “UV-3000B” [“UV-3000B” sold by Nippon Synthetic Chemical Industry Co., Ltd.] and bifunctional urethane acrylate “UV-3700B” [from Nippon Synthetic Chemical Industry Co., Ltd.] Although “UV-3700B”] on the market is disclosed as an ultraviolet curable resin mainly composed of urethane acrylate, a specific structure is not disclosed. In the manufacturer catalog, for bifunctional urethane acrylate "UV-3000B", viscosity: 45,000-65,000 mPa · s / 60 ° C, molecular weight (Mw): 18,000, number of oligomer functional groups: 2, glass transition temperature Tg : Physical property of -39 ° C. is shown, viscosity: 30,000 to 60,000 mPa · s / 60 ° C., molecular weight (Mw): 38,000, number of oligomer functional groups per bifunctional urethane acrylate “UV-3700B” 2: Physical properties of glass transition temperature Tg: −6 ° C. are shown.

[Production Example 7] Preparation of curable resin compositions D to Q As N-substituted acrylamide, N, N-dimethylacrylamide, a compound having an acryloyloxy group in the molecule, two or three of those shown above, Photo radical polymerization initiator “Irgacure 907” and silicone leveling agent “SH710” were mixed in the following proportions to prepare curable resin compositions D to Q, respectively.

Curable resin composition D
N, N-dimethylacrylamide 5 parts 4-hydroxybutyl acrylate 30 parts 1,4-cyclohexanedimethanol monoacrylate 64 parts trimethylolpropane triacrylate 1 part Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710 ”0.2 part

Curable resin composition E
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 30 parts Ethoxylated glycerol triacrylate 50 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710" 0.2 parts

Curable resin composition F
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Ethoxylated glycerin triacrylate 45 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710" 0.2 parts

Curable resin composition G
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 40 parts Ethoxylated glycerin triacrylate 40 parts Photoradical polymerization initiator “Irgacure 907” 3 parts Silicone leveling agent “SH710” 0.2 parts

Curable resin composition H
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Ethoxylated glycerin triacrylate 35 parts Polyethylene glycol # 600 Diacrylate 10 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710" 0. 2 parts

Curable resin composition I
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Ethoxylated glycerin triacrylate 10 parts Polyethylene glycol # 600 Diacrylate 35 parts Photoradical polymerization initiator “Irgacure 907” 3 parts Silicone leveling agent “SH710” 0. 2 parts

Curable resin composition J
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Ethoxylated glycerin triacrylate 35 parts Bifunctional urethane acrylate "UV-3000B" 10 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710 ”0.2 part

Curable resin composition K
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Ethoxylated glycerin triacrylate 25 parts Bifunctional urethane acrylate "UV-3000B" 20 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710 ”0.2 part

Curable resin composition L
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Ethoxylated glycerin triacrylate 10 parts Bifunctional urethane acrylate “UV-3000B” 35 parts Photoradical polymerization initiator “Irgacure 907” 3 parts Silicone leveling agent “SH710 ”0.2 part

Curable resin composition M
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Ethoxylated glycerin triacrylate 35 parts Bifunctional urethane acrylate "UV-3700B" 10 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710 ”0.2 part

Curable resin composition N
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Ethoxylated glycerin triacrylate 25 parts Bifunctional urethane acrylate "UV-3700B" 20 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710 ”0.2 part

Curable resin composition O
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Ethoxylated glycerin triacrylate 10 parts Bifunctional urethane acrylate "UV-3700B" 35 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710 ”0.2 part

Curable resin composition P
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Polyethylene glycol # 600 Diacrylate 45 parts Photoradical polymerization initiator "Irgacure 907" 3 parts Silicone leveling agent "SH710" 0.2 parts

Curable resin composition Q
N, N-dimethylacrylamide 20 parts Dicyclopentanyl acrylate 35 parts Polyethylene glycol # 600 Diacrylate 25 parts Bifunctional urethane acrylate “UV-3700B” 20 parts Photoradical polymerization initiator “Irgacure 907” 3 parts Silicone leveling agent “ SH710 ”0.2 part

[Production Example 8] Preparation of curable resin composition Z Only dicyclopentanyl acrylate was used as a curable component, and photo radical polymerization initiator "Irgacure 907" and silicone leveling agent "SH710" were added to the following: The curable resin composition Z was prepared by mixing each at a ratio.

Curable resin composition Z
Dicyclopentanyl acrylate 100 parts Photoradical polymerization initiator “Irgacure 907” 3 parts Silicone leveling agent “SH710” 0.2 parts

[Examples 9 to 22]
Instead of the curable resin composition A, each of the curable resin compositions D to Q prepared in Production Example 7 was used, and the film thickness after curing was applied so as to have the values shown in Table 2, and the others were carried out. In the same manner as in Example 1, a composite retardation plate was produced.

[Comparative Example 8]
Instead of the curable resin composition A, the curable resin composition Z prepared in Production Example 8 was used and applied so that the film thickness after curing was 1 μm, and the others were operated in the same manner as in Example 1. A composite retardation plate was produced.

  Measurement of the glass transition temperature of the adhesive layer obtained by curing the curable resin compositions D to Q and Z, and the evaluation of the adhesive force of the composite retardation plate produced in Examples 9 to 22 and Comparative Example 8, The same method as described above was performed, and the results are summarized in Table 2. In Table 2, the column “monofunctional acrylate” means a compound having one acryloyloxy group in the molecule, and the column “polyfunctional acrylate” has two or more acryloyloxy groups in the molecule. Means a compound.

  As shown in Table 2, as a compound having a (meth) acryloyloxy group in the molecule, a monofunctional acrylate and a polyfunctional acrylate are used in combination, and this is combined with N-substituted acrylamide to form a curable component. It is possible to further reduce the thickness of the adhesive layer while maintaining an appropriate adhesive force between the retardation plate and the second retardation plate.

10: First retardation plate,
12 ... retardation development layer,
14, 15 ... (meth) acrylic resin layer,
18 …… Second retardation plate,
20 …… Composite retardation plate,
31 …… Adhesive layer
32 …… Second adhesive layer,
33. Third adhesive layer,
42 …… Polarizing film,
44 …… Protective film,
46 …… Adhesive layer,
48 …… Separator,
50: Composite polarizing plate.

Claims (10)

An adhesive layer made of a cured product of an active energy ray-curable resin composition on the (meth) acrylic resin layer of the first retardation plate having a (meth) acrylic resin layer on the outermost surface, and a cycloolefin type A second retardation plate made of a resin film is laminated in this order,
The active energy ray-curable resin composition contains N-substituted (meth) acrylamide and a compound having a (meth) acryloyloxy group in the molecule as a curable component,
The composite phase difference plate, wherein the adhesive layer has a thickness of 10 μm or less. The N-substituted (meth) acrylamide has the following formula (I)

(In the formula, Q ₁ represents a hydrogen atom or a methyl group, Q ₂ represents a hydrogen atom or an alkyl group having 1 to 6 carbon atoms, and Q ₃ has 1 to 6 carbon atoms which may have a hydroxyl group or an amino group. Or Q ₂ and Q ₃ together form a 5-membered or 6-membered ring which may have an oxygen atom as a ring member together with the nitrogen atom to which they are bonded)
The composite phase difference plate of Claim 1 shown by these.   The compound having a (meth) acryloyloxy group contains a compound having one (meth) acryloyloxy group in the molecule and a compound having two or more (meth) acryloyloxy groups in the molecule. Or the composite phase difference plate of 2.   The said 1st phase difference plate is a composite phase difference plate in any one of Claims 1-3 containing the phase difference expression layer which consists of other resin in addition to the said (meth) acrylic-type resin layer.   5. The composite retardation plate according to claim 4, wherein the retardation developing layer has a glass transition temperature of 120 ° C. or higher, and the (meth) acrylic resin layer has a glass transition temperature of 120 ° C. or lower.   The composite phase difference plate according to claim 4, wherein the retardation layer is made of a styrene resin.   The composite phase difference plate according to claim 4, wherein the (meth) acrylic resin layer contains rubber particles.   The composite retardation plate according to any one of claims 4 to 7, wherein the first retardation plate is obtained by forming the (meth) acrylic resin layer on both surfaces of the retardation developing layer.   The composite retardation plate according to claim 8, wherein each of the retardation developing layer and the (meth) acrylic resin layer formed on both surfaces thereof has a thickness of 5 to 100 μm.   A protective film made of a thermoplastic resin is laminated on one surface of a polarizing film having a dichroic dye adsorbed and oriented on a polyvinyl alcohol-based resin, and the other surface of the polarizing film. Furthermore, the composite phase difference plate in any one of Claims 1-9 is laminated | stacked by the cycloolefin type resin film side through the 3rd adhesive bond layer.

Images