JP2009139658A - Multilayer optical film - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multilayer optical film which is excellent in resistance to scuffing and hardly changes optical characteristics thereof even under heating and humidification. <P>SOLUTION: In the multilayer optical film, a first protective film F1 of which at least one side film surface has a contact angle with water of ≤40°, a polarizer P, and a second protective film F2 including a transparent resin of which the absolute value of photo-elastic coefficient of ≤1.0×10<SP>-11</SP>m<SP>2</SP>/N are stacked in the order, wherein a hardened layer H which is formed by using a hardened layer formation material including a component (A), a component (B) and a component (C) is disposed on the principal surface of the first protective film F1, where the polarizer is not stacked. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a laminated optical film provided with a cured layer. Furthermore, this invention relates to the image display apparatus using the said optical film.

  In the liquid crystal display device, a polarizing plate is attached to one side or both sides of a liquid crystal cell in which liquid crystal is sealed between two electrode substrates on which transparent electrodes are formed because of the image forming method. As a polarizing plate used in such a liquid crystal display device, a triacetyl cellulose film is usually provided on both sides of a polarizer obtained by adsorbing and stretching and orienting a dichroic material such as iodine or a dichroic dye on a polyvinyl alcohol film. In general, a film obtained by bonding a protective film or the like via a polyvinyl alcohol-based adhesive is used. In addition, since the polarizing plate is disposed on the outermost surface of the liquid crystal display device, a cover plate such as glass is attached to prevent scratches, or the surface of the polarizing plate is hardened from the viewpoint of cost and weight reduction. A hardened layer is often provided by a coating treatment or the like.

  In the hard coat treatment, a hard coat film in which a thin cured layer having a thickness of 2 to 3 μm is formed on one side or both sides of a transparent plastic film base is generally used. For example, a hard coat film (for example, Patent Document 1) in which a cured coating layer made of a composition containing an ultraviolet curable polyol (meth) acrylate resin is formed, and a hard coat film in which a cured layer is formed on a buffer layer ( For example, Patent Document 2), a hard coat film (for example, Patent Document 3) provided with a cured resin coating layer in which a thin film of a clear cured resin is provided on a cured resin layer containing internally crosslinked ultrafine particles, a solvent-dried resin Hard coat films (for example, Patent Document 4) used for the cured layer are known. However, these hard coat films have complicated manufacturing processes, insufficient surface hardness, and curling. Or the cured layer may peel off.

  On the other hand, a hard coat film having sufficient hardness is disclosed by a cured layer containing urethane acrylate, polyol (meth) acrylate, and (meth) acrylic polymer (for example, Patent Document 5).

Japanese Laid-Open Patent Publication No. 9-11728 JP-A-11-300873 JP 2000-52472 A JP 7-287102 A JP 2007-171943 A

  In a liquid crystal display device, particularly a small and medium-sized liquid crystal display device used for a mobile device such as a mobile phone, in addition to the surface hardness as described above, a change in optical characteristics may be small even under conditions such as high temperature and high humidity. It has been demanded. However, since the polarizing plate has a plurality of layers including a hardened layer, and each layer has a different thermal contraction rate, thermal expansion coefficient, etc., the dimensions change under severe conditions such as heating and humidification. Along with this, there is a problem in that stress is generated at the interface of each layer to cause a change in optical characteristics or display unevenness (thermal unevenness). In particular, when a hardened layer is provided, the thermal behavior is significantly different from that of a normal polymer film layer, so that the behavior of changes in optical properties and occurrence of thermal unevenness tends to be difficult to predict. When the structure of the Example of patent document 5 was examined, although generation | occurrence | production of the heat nonuniformity was suppressed compared with the polarizing plate which provided the conventional hardened layer, it could not be said to be enough.

  In view of the above viewpoint, an object of the present invention is to provide a laminated optical film having excellent scratch resistance and little change in optical properties even under heating and humidification.

  As a result of intensive studies, the inventors of the present invention have found that an optical film having a high surface hardness and less heat unevenness in a heating and humidifying environment, that is, excellent durability can be obtained by a specific configuration. The present invention has been reached.

That is, in the present invention, the absolute value of the first protective film F1 having a contact angle with water of at least one film surface of 40 degrees or less, the polarizer P, and the photoelastic coefficient is 1.0 × 10 ⁻¹¹ m. The second protective film F2 containing a transparent resin that is ² / N or less is laminated in this order, and on the main surface on which the polarizer of the first protective film F1 is not laminated, the following (A) component, (B) It is related with the laminated optical film which has the hardened layer H formed using the hardened layer forming material containing a component and (C) component.
(A) Component: At least one of urethane acrylate and urethane methacrylate (B) Component: At least one of polyol acrylate and polyol methacrylate (C) Component: Polymer or copolymer formed from at least one of the following (C1) and (C2) Or the mixed polymer (C1) including the polymer or the copolymer: an alkyl acrylate having an alkyl group having at least one group of a hydroxyl group and an acryloyl group (C2): having an alkyl group having at least one group of a hydroxyl group and an acryloyl group Alkyl methacrylate

  By adopting such a configuration, a laminated optical film having a high surface hardness and excellent durability can be obtained.

  In the laminated optical film of the present invention, the polarizer P and the second protective film F2 are laminated via an adhesive layer, and the adhesive layer has a polyvinyl alcohol resin, a crosslinking agent, and an average particle size. It is a resin solution containing a metal compound colloid of 1 to 100 nm, and the metal compound colloid is blended at a ratio of 200 parts by weight or less with respect to 100 parts by weight of the polyvinyl alcohol resin. It is preferable that it is formed of an adhesive.

  By adopting such a configuration, it is possible to suppress the occurrence of uneven defects (knicks) and to solve problems such as the image display device appearing to lose light.

  In the laminated optical film of the present invention, the second protective film F2 preferably contains an acrylic resin or a cyclic polyolefin resin. Furthermore, it is preferable that the first protective film F1 contains a cellulose resin.

  Furthermore, the present invention relates to a laminated optical film having at least one optical compensation layer R on the second protective film F2 side of the laminated optical film.

  With this configuration, it is possible to obtain an optical compensation polarizing plate with less occurrence of thermal unevenness in a heating / humidifying environment as compared with a laminated optical film having a conventional optical compensation layer.

  Furthermore, the present invention relates to an image display device having the laminated optical film.

(Configuration of laminated optical film)
In the laminated optical film of the present invention, as shown in FIG. 1, a first protective film F1, a polarizer P, and a second protective film F2 are laminated in this order, and the polarizer of the first protective film is It has the hardened layer H on the main surface which is not laminated | stacked. Hereinafter, each component forming the laminated optical film will be described in detail.

(First protective film)
As the 1st protective film F1 used for the lamination | stacking optical film of this invention, a contact angle with the water of the at least one film surface is 40 degrees or less is used. The contact angle with water is more preferably 35 ° or less, and further preferably 30 ° or less. The contact angle with water generally correlates with the wettability with respect to the hydrophilic liquid. However, when the contact angle is large, the wettability with respect to the hydrophilic liquid is low, and it becomes difficult to form the cured layer H described later. Adhesion between the formed cured layer and the first protective film may be insufficient.

  If the surface of at least one film has said contact angle, the material will not be limited for a 1st protective film, Arbitrary things can be used. As such a material, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property and the like is used. Specific examples of such thermoplastic resins include cellulose resins such as triacetyl cellulose, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, polyamide resins, polyimide resins, polyolefin resins. , (Meth) acrylic resins, cyclic polyolefin resins (norbornene resins), polyarylate resins, polystyrene resins, polyvinyl alcohol resins, and mixtures thereof.

  Among the substrates, it is preferable to use a substrate containing a hydrophilic group such as a hydroxyl group on the surface thereof. Among these materials, cellulose-based resins, polyester-based resins, (meth) acrylic resins, polyvinyl alcohol-based resins, and the like are preferably used as materials that contain a hydrophilic group such as a hydroxyl group in the molecular structure.

  Moreover, even if it is a base material which does not contain a hydrophilic group on the surface, it can be made into a base material with high wettability, ie, a small contact angle of water, by surface treatment. Surface treatment includes dry treatment such as corona treatment, gas corona treatment, sputtering treatment, low-pressure UV irradiation, or plasma treatment, and an easy-adhesion layer made of cellulose ester resin, urethane-modified copolymer polyester resin, silane coupling agent, or the like. Examples include formation or alkali treatment (saponification treatment). Among these surface treatments, alkali treatment is preferable. As a method for the alkali treatment, for example, the substrate is immersed in a 1 to 20% by weight aqueous sodium hydroxide solution for about 10 seconds to 20 minutes, and then washed with pure water and dried.

  In particular, among the above, a cellulose resin film is preferably used, and at least one surface of which is alkali-treated can be more preferably used. Cellulosic resins include fatty acid esters in which the hydroxyl groups of cellulose are acylated with fatty acids, cellulose ethers in which the hydroxyl groups of cellulose are etherified with sodium alkoxides, and the like. In particular, cellulose and fatty acid esters are preferably used. . Specific examples of the cellulose ester resin include triacetyl cellulose, diacetyl cellulose, tripropionyl cellulose, dipropionyl cellulose, and the like. Among these, triacetyl cellulose is particularly preferable. Many products of triacetylcellulose are commercially available, which is advantageous in terms of availability and cost. Examples of commercial products of triacetyl cellulose include trade names “UV-50”, “UV-80”, “SH-80”, “TD-80U”, “TD-TAC”, “UZ” manufactured by Fuji Film Co., Ltd. -TAC "and" KC series "manufactured by Konica Minolta. Triacetylcellulose has a lower hydroxyl group content than diacetylcellulose or the like, but the contact angle with water can be reduced by hydrophilizing the surface by alkali treatment or the like as described above.

(Second protective film)
As the second protective film F2 used in the laminated optical film of the present invention, a film having a photoelastic coefficient of 1.0 × 10 ⁻¹¹ m ² / N or less is used. The photoelastic coefficient is an index representing the inclination of birefringence change with respect to stress when an external force is applied to the optical film, that is, the ease of occurrence of birefringence with respect to the stress. Value. The photoelastic coefficient of the second protective film is more preferably 7.0 × 10 ⁻¹² m ² / N or less, and further preferably 5.0 × 10 ⁻¹² m ² / N or less. When the photoelastic coefficient of the second optical film is large, the optical characteristics change when the laminated optical film is exposed to a heating environment, and the image display tends to be uneven due to heat unevenness or the like. The lower limit of the photoelastic coefficient is not particularly limited, but is generally 5.0 × 10 ⁻¹³ m ² / N or more.

  The material of the second protective film is not limited as long as the photoelastic coefficient is within the above range, and any material can be used. As such a material, for example, a thermoplastic resin excellent in transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is used. From the viewpoint that the photoelastic coefficient is small, a cyclic polyolefin type is used. Examples include resins (norbornene resins), (meth) acrylic resins, polystyrene resins, and mixtures thereof. It is also preferable to use a film having a photoelastic coefficient further reduced by a copolymer or mixture of a polymer having a positive photoelastic coefficient and a polymer having a negative photoelastic coefficient.

  Specific examples of the cyclic polyolefin resin are preferably norbornene resins. The cyclic polyolefin resin is a general term for resins that are polymerized using a cyclic olefin as a polymerization unit, and is described in, for example, JP-A-1-240517, JP-A-3-14882, JP-A-3-122137, and the like. Resin. Specific examples include ring-opening (co) polymers of cyclic olefins, addition polymers of cyclic olefins, cyclic olefins and α-olefins such as ethylene and propylene (typically random copolymers), And the graft polymer which modified these with unsaturated carboxylic acid or its derivative (s), those hydrides, etc. are mentioned. Specific examples of the cyclic olefin include norbornene monomers.

  Various products are commercially available as the cyclic polyolefin resin. Specific examples include trade names “ZEONEX” and “ZEONOR” manufactured by ZEON CORPORATION, trade names “ARTON” manufactured by JSR Corporation, “TOPAS” trade names manufactured by TICONA, and trade names manufactured by Mitsui Chemicals, Inc. “Apel” and the like.

  As the (meth) acrylic resin, those having a Tg (glass transition temperature) of preferably 115 ° C. or higher, more preferably 120 ° C. or higher, further preferably 125 ° C. or higher, particularly preferably 130 ° C. or higher are used. When Tg is 115 ° C. or higher, a laminated optical film having excellent heat durability can be obtained. Although the upper limit of Tg of the (meth) acrylic resin is not particularly limited, it is preferably 170 ° C. or less from the viewpoint of moldability. From the (meth) acrylic resin, a film having a small photoelastic coefficient, an in-plane retardation (Re), and a thickness direction retardation (Rth) of almost zero can be obtained.

  As the (meth) acrylic resin, any appropriate (meth) acrylic resin can be adopted as long as the effects of the present invention are not impaired. For example, poly (meth) acrylic acid ester such as polymethyl methacrylate, methyl methacrylate- (meth) acrylic acid copolymer, methyl methacrylate- (meth) acrylic acid ester copolymer, methyl methacrylate-acrylic acid ester- (Meth) acrylic acid copolymer, (meth) methyl acrylate-styrene copolymer (MS resin, etc.), a polymer having an alicyclic hydrocarbon group (for example, methyl methacrylate-cyclohexyl methacrylate copolymer, Methyl methacrylate- (meth) acrylate norbornyl copolymer, etc.). Preferably, poly (meth) acrylic acid C1-6 alkyl such as poly (meth) acrylate methyl is used. More preferred is a methyl methacrylate-based resin containing methyl methacrylate as a main component (50 to 100% by weight, preferably 70 to 100% by weight).

  Specific examples of (meth) acrylic resins include (meth) acrylic resins having a ring structure in the molecule described in, for example, Acrypet VH and Acrypet VRL20A manufactured by Mitsubishi Rayon Co., Ltd., and JP-A-2004-70296. And high Tg (meth) acrylic resins obtained by intramolecular crosslinking or intramolecular cyclization reaction.

  As the (meth) acrylic resin, a (meth) acrylic resin having a lactone ring structure can also be used. It is because it has high mechanical strength by high heat resistance, high transparency, and biaxial stretching.

  Examples of the (meth) acrylic resin having a lactone ring structure include JP 2000-230016, JP 2001-151814, JP 2002-120326, JP 2002-254544, and JP 2005. Examples thereof include (meth) acrylic resins having a lactone ring structure described in Japanese Patent No. 146084.

The (meth) acrylic resin having a lactone ring structure preferably has a ring pseudo structure represented by the following general formula (I).

_Wherein, R 1, _{R 2} and _{R 3} each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The content of the lactone ring structure represented by the general formula (I) in the structure of the (meth) acrylic resin having a lactone ring structure is preferably 5 to 90% by weight, more preferably 10 to 70% by weight, The amount is preferably 10 to 60% by weight, particularly preferably 10 to 50% by weight. If the content of the lactone ring structure represented by the general formula (I) in the structure of the (meth) acrylic resin having a lactone ring structure is less than 5% by weight, heat resistance, solvent resistance, and surface hardness are poor. May be sufficient. If the content of the lactone ring structure represented by the general formula (I) in the structure of the (meth) acrylic resin having a lactone ring structure is more than 90% by weight, molding processability may be poor.

  The (meth) acrylic resin having a lactone ring structure has a mass average molecular weight (sometimes referred to as a weight average molecular weight) of preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, and particularly preferably. Is 50,000 to 500,000. If the mass average molecular weight is out of the above range, it is not preferable from the viewpoint of moldability.

  The (meth) acrylic resin having a lactone ring structure is preferably as the total light transmittance of a molded product obtained by injection molding measured by a method according to ASTM-D-1003 is higher, preferably 85. % Or more, more preferably 88% or more, and still more preferably 90% or more. The total light transmittance is a measure of transparency. If the total light transmittance is less than 85%, the transparency may be lowered.

  Moreover, as a 2nd protective film, the polymer film as described in Unexamined-Japanese-Patent No. 2001-343529 (WO01 / 37007), for example, (A) thermoplastic resin which has a substituted and / or unsubstituted imide group in a side chain, B) A film comprising a resin composition containing a thermoplastic resin having a substituted and / or unsubstituted phenyl and nitrile group in the side chain can also be used. Specific examples include a film of a resin composition containing an alternating copolymer composed of isobutylene and N-methylmaleimide and an acrylonitrile / styrene copolymer. As the film, a film made of a mixed extruded product of the resin composition or the like can be used. These films have a small phase difference and a small photoelastic coefficient so that problems such as unevenness due to the distortion of the polarizing plate can be eliminated. Also, since the moisture permeability is small, the polarizing plate can be used as a protective film for a polarizer. Excellent humidification durability.

  Among other (meth) acrylic materials, those having a particularly small photoelastic coefficient are disclosed in JP-A-2004-70290, JP-A-2004-70296, JP-A-2004-163924, and JP-A-2004-292812. JP, JP 2005-314534, JP 2006-131898, JP 2006-206881, JP 2006-265532, JP 2006-283013, JP 2006-299005, A polymer film containing an acrylic resin having a structural unit of an unsaturated carboxylic acid alkyl ester and a structural unit of glutaric anhydride described in JP 2006-335902 A, JP 2006-309033 A, JP JP 2006-317560 A, JP 2006-328329 A No. 2006-328334, JP-A 2006-337491, JP-A 2006-337492, JP-A 2006-337493, JP-A 2006-337469, etc. Examples thereof include a film containing a thermoplastic resin.

  Examples of the styrenic resin include, as monomer units, styrene, α-methylstyrene, o-methylstyrene, p-methylstyrene, p-chlorostyrene, p-nitrostyrene, p-aminostyrene, p-carboxystyrene, p. -What contains phenyl styrene, 2, 5- dichloro styrene, pt-butyl styrene, etc. are mentioned.

  Moreover, as a copolymer of a styrene monomer and another monomer, a styrene-maleic anhydride copolymer, an acrylonitrile copolymer, a styrene- (meth) acrylate copolymer, a styrene-maleimide copolymer, vinyl An ester-maleimide copolymer, an olefin-maleimide copolymer, or the like can also be used. These can also be used individually by 1 type, and can also be used in mixture of 2 or more types.

(Characteristics of each protective film)
One or more kinds of arbitrary appropriate additives may be contained in the first protective film and the second protective film. Examples of the additive include an ultraviolet absorber, an antioxidant, a lubricant, a plasticizer, a mold release agent, a coloring inhibitor, a flame retardant, a nucleating agent, an antistatic agent, a pigment, and a coloring agent. The content of the thermoplastic resin in the transparent protective layer is preferably 50 to 100% by weight, more preferably 50 to 99% by weight, still more preferably 60 to 98% by weight, and particularly preferably 70 to 97% by weight. . If the content of the thermoplastic resin in the transparent protective layer is 50% by weight or less, the high transparency inherent in the thermoplastic resin may not be sufficiently exhibited.

  Moreover, although the thickness of a 1st protective film and a 2nd protective film can be determined suitably, generally it is about 1-500 micrometers from points, such as workability | operativity, such as intensity | strength and handleability, and thin-layer property. 1-300 micrometers is especially preferable, and 5-200 micrometers is more preferable. The transparent protective layer is particularly suitable when the thickness is 5 to 150 μm.

  As the first protective film and the second protective film, those having a front phase difference of less than 40 nm and a thickness direction retardation of less than 80 nm are usually used. In particular, when the laminated optical film of the present invention is used in a liquid crystal display device as will be described later, since the second protective film is disposed between the liquid crystal cell and the polarizer, the optical characteristics greatly affect the display characteristics. Effect. Therefore, it is necessary to examine especially the optical characteristic of a 2nd protective film. That is, a laminated optical film having a small optical distortion can be obtained by selecting a second protective film having a small front retardation and thickness direction retardation. The front phase difference Re is represented by Re = (nx−ny) × d. The thickness direction retardation Rth is represented by Rth = (nx−nz) × d. The Nz coefficient is represented by Nz = (nx−nz) / (nx−ny). [However, the refractive indexes in the slow axis direction, the fast axis direction, and the thickness direction of the film are nx, ny, and nz, respectively, and d (nm) is the thickness of the film. The slow axis direction is the direction that maximizes the refractive index in the film plane. ].

  In particular, by using the above-mentioned cyclic polyolefin resin or (meth) acrylic resin for the second protective film, not only the front phase difference but also the thickness direction phase difference is, for example, 20 nm or less, more preferably 10 nm or less. Can do.

  On the other hand, as the second protective film, a film having a front phase difference of 40 nm or more and / or a thickness direction retardation of 80 nm or more can be used. The front phase difference is usually controlled in the range of 40 to 200 nm, and the thickness direction phase difference is usually controlled in the range of 80 to 300 nm. When a retardation plate is used as the transparent protective layer, the retardation plate functions also as a transparent protective layer, so that the thickness can be reduced.

  Thus, what has a phase difference includes a birefringent film obtained by uniaxially or biaxially stretching a polymer material, or a film in which an alignment layer of a liquid crystalline polymer is supported by a film.

(Polarizer)
As the polarizer P used in the laminated optical film of the present invention, among the orthogonal linearly polarized light, polarized light having a vibration surface parallel to the transmission axis is transmitted as it is, and polarization having a vibration surface parallel to the absorption axis is selectively used. Can be used. Examples of such a polarizer include a film obtained by adsorbing a dichroic substance on a hydrophilic polymer film and stretching in the width direction, a film in which a dichroic dye exhibiting lyotropic liquid crystal properties is oriented, and a homogeneous material. Examples thereof include those in which a dichroic dye is oriented in a matrix of an oriented thermotropic liquid crystalline polymer or a homogeneously oriented crosslinkable liquid crystalline polymer.

  Among such polarizers, from the viewpoint of having a high degree of polarization, a polyvinyl alcohol polarizer containing iodine is preferably used. Polyvinyl alcohol or a derivative thereof is used as a material for the polyvinyl alcohol film applied to the polarizer. Derivatives of polyvinyl alcohol include polyvinyl formal, polyvinyl acetal, and the like, olefins such as ethylene and propylene, unsaturated carboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, and their alkyl esters and acrylamide. Things. Polyvinyl alcohol having a polymerization degree of about 1000 to 10000 and a saponification degree of about 80 to 100 mol% is generally used.

  The polyvinyl alcohol film may contain an additive such as a plasticizer. Examples of the plasticizer include polyols and condensates thereof, and examples thereof include glycerin, diglycerin, triglycerin, ethylene glycol, propylene glycol, and polyethylene glycol. The amount of the plasticizer used is not particularly limited, but is preferably 20% by weight or less in the polyvinyl alcohol film.

  The polyvinyl alcohol film (unstretched film) is at least subjected to uniaxial stretching treatment and iodine dyeing treatment according to a conventional method. Furthermore, boric acid treatment and iodine ion treatment can be performed. Moreover, the polyvinyl alcohol film (stretched film) subjected to the treatment is dried according to a conventional method to form a polarizer.

  The stretching method in the uniaxial stretching treatment is not particularly limited, and either a wet stretching method or a dry stretching method can be employed. Examples of the stretching means of the dry stretching method include an inter-roll stretching method, a heated roll stretching method, and a compression stretching method. Stretching can also be performed in multiple stages. In the stretching means, the unstretched film is usually heated. Usually, an unstretched film having a thickness of about 30 to 150 μm is used. The stretch ratio of the stretched film can be appropriately set according to the purpose, but the stretch ratio (total stretch ratio) is about 2 to 8 times, preferably 3 to 6.5 times, more preferably 3.5 to 6 times. Is desirable. The thickness of the stretched film is preferably about 5 to 40 μm.

  The iodine staining treatment is performed by immersing the polyvinyl alcohol film in an iodine solution containing iodine and potassium iodide. The iodine solution is usually an iodine aqueous solution, and contains iodine and potassium iodide as a dissolution aid. The iodine concentration is about 0.01 to 1% by weight, preferably 0.02 to 0.5% by weight. The potassium iodide concentration is about 0.01 to 10% by weight, and further 0.02 to 8% by weight. It is preferable to use it.

  In the iodine dyeing treatment, the temperature of the iodine solution is usually about 20 to 50 ° C, preferably 25 to 40 ° C. The immersion time is usually about 10 to 300 seconds, preferably 20 to 240 seconds. In the iodine dyeing treatment, the iodine content and potassium content in the polyvinyl alcohol film are within the above ranges by adjusting the conditions such as the concentration of the iodine solution, the immersion temperature of the polyvinyl alcohol film in the iodine solution, and the immersion time. Adjust as follows. The iodine dyeing process may be performed at any stage before the uniaxial stretching process, during the uniaxial stretching process, or after the uniaxial stretching process.

  The boric acid treatment is performed by immersing a polyvinyl alcohol film in an aqueous boric acid solution. The boric acid concentration in the boric acid aqueous solution is about 2 to 15% by weight, preferably 3 to 10% by weight. The aqueous boric acid solution can contain potassium ions and iodine ions with potassium iodide. The potassium iodide concentration in the boric acid aqueous solution is preferably about 0.5 to 10% by weight, more preferably 1 to 8% by weight. A boric acid aqueous solution containing potassium iodide can provide a lightly colored polarizer, that is, a so-called neutral gray polarizer having a substantially constant absorbance over almost the entire wavelength range of visible light.

  For the iodine ion treatment, for example, an aqueous solution containing iodine ions with potassium iodide or the like is used. The potassium iodide concentration is preferably about 0.5 to 10% by weight, more preferably 1 to 8% by weight. In the iodine ion impregnation treatment, the temperature of the aqueous solution is usually about 15 to 60 ° C, preferably 25 to 40 ° C. The immersion time is usually about 1 to 120 seconds, preferably 3 to 90 seconds. The stage of iodine ion treatment is not particularly limited as long as it is before the drying process. It can also be performed after water washing described later.

  The polarizer can also contain zinc. Inclusion of zinc in the polarizer is preferable in terms of suppressing hue deterioration during heating durability. The zinc content in the polarizer is preferably adjusted so that the zinc element is contained in the polarizer in an amount of 0.002 to 2% by weight. Furthermore, it is preferable to adjust to 0.01 to 1 weight%. When the zinc content in the polarizer is within the above range, the durability improving effect is good, which is preferable for suppressing the deterioration of the hue.

  A zinc salt aqueous solution is used for the zinc impregnation treatment. As the zinc salt, an inorganic salt compound of an aqueous solution such as zinc halides such as zinc chloride and zinc iodide, zinc sulfate, and zinc acetate is preferable. Among these, zinc sulfate is preferable because the retention rate of zinc in the polarizer can be increased. Various zinc complex compounds can be used for the zinc impregnation treatment. The concentration of zinc ions in the zinc salt aqueous solution is about 0.1 to 10% by weight, preferably 0.3 to 7% by weight. In addition, it is preferable to use an aqueous solution containing potassium ions and iodine ions with potassium iodide or the like because the zinc salt aqueous solution is easily impregnated with zinc ions. The potassium iodide concentration in the zinc salt aqueous solution is preferably about 0.5 to 10% by weight, more preferably 1 to 8% by weight.

  In the zinc impregnation treatment, the temperature of the zinc salt aqueous solution is usually about 15 to 85 ° C, preferably 25 to 70 ° C. The immersion time is usually about 1 to 120 seconds, preferably 3 to 90 seconds. In the zinc impregnation treatment, the zinc content in the polyvinyl alcohol film can be adjusted by adjusting conditions such as the concentration of the zinc salt aqueous solution, the immersion temperature of the polyvinyl alcohol film in the zinc salt aqueous solution, and the immersion time. The stage of the zinc impregnation treatment is not particularly limited, and may be before the iodine dyeing treatment, before the immersion treatment in the boric acid aqueous solution after the iodine dyeing treatment, during the boric acid treatment, or after the boric acid treatment. Further, it may be carried out simultaneously with the iodine dyeing treatment in the presence of a zinc salt in the iodine dyeing solution. The zinc impregnation treatment is preferably performed together with boric acid treatment. Moreover, a uniaxial stretching process can also be performed with a zinc impregnation process. Moreover, you may perform a zinc impregnation process in multiple times.

  The treated polyvinyl alcohol film (stretched film) can be subjected to a water washing step and a drying step according to a conventional method.

  The water washing step is usually performed by immersing a polyvinyl alcohol film in pure water. The water washing temperature is usually in the range of 5 to 50 ° C, preferably 10 to 45 ° C, more preferably 15 to 40 ° C. The immersion time is usually about 10 to 300 seconds, preferably about 20 to 240 seconds.

  Arbitrary appropriate drying methods, for example, natural drying, ventilation drying, heat drying, etc., can be adopted as the drying step. For example, in the case of heat drying, the drying temperature is typically 20 to 80 ° C., preferably 25 to 70 ° C., and the drying time is typically about 1 to 10 minutes. Further, the moisture content of the polarizer after drying is preferably 10 to 30% by weight, more preferably 12 to 28% by weight, and even more preferably 16 to 25% by weight. When the moisture content is excessively large, a laminated laminate in which a polarizer is bonded to an optical element or a transparent protective film via an adhesive layer as described later, that is, when the polarizer is dried, the polarizer is dried. Therefore, the degree of polarization tends to decrease. In particular, the orthogonal transmittance increases in a short wavelength region of 500 nm or less, that is, light of a short wavelength leaks, so that black display tends to be colored blue. On the other hand, if the moisture content of the polarizer is excessively small, problems such as local uneven defects (knic defects) are likely to occur.

  In the laminated optical film of the present invention, the cured layer H is provided on the main surface on which the polarizer P of the first protective film F1 is not laminated. The surface on which the cured layer H is provided is equal to the surface of the first protective film F1 having a contact angle with water of 40 degrees or less. That is, when the contact angle with water on one main surface of the first protective film is 40 degrees or less and the contact angle with water on the other main surface is larger than 40 degrees, the contact angle is larger than 40 degrees on the main surface side. The polarizer P is laminated, and a hardened layer H is provided on the main surface with a contact angle of 40 degrees or less. Moreover, when the contact angle with the water of both the main surfaces of a 1st protective film is 40 degrees or less, you may provide a hardened layer in which main surface.

(Cured layer)
The cured layer H is formed using a cured layer forming material containing the following component (A), component (B), and component (C).
(A) Component: At least one of urethane acrylate and urethane methacrylate (B) Component: At least one of polyol acrylate and polyol methacrylate (C) Component: Polymer or copolymer formed from at least one of the following (C1) and (C2) Or a mixed polymer containing the polymer or the copolymer (C1): an alkyl acrylate having an alkyl group having at least one of a hydroxyl group and an acryloyl group (C2): an alkyl group having at least one group of a hydroxyl group and an acryloyl group Alkyl methacrylate

  As said urethane acrylate and urethane methacrylate which are said (A) component, what contains acrylic acid, methacrylic acid, acrylic ester, methacrylic ester, a polyol, and diisocyanate as a structural component is used. For example, using at least one monomer of acrylic acid, methacrylic acid, acrylic ester and methacrylic ester and a polyol, at least one of hydroxy acrylate having one or more hydroxyl groups and hydroxy methacrylate having one or more hydroxyl groups is produced. Then, at least one of urethane acrylate and urethane methacrylate can be produced by reacting this with diisocyanate. In the component (A), urethane acrylate and urethane methacrylate may be used alone or in combination of two or more.

  Examples of acrylic esters include alkyl acrylates such as methyl acrylate, ethyl acrylate, isopropyl acrylate, and butyl acrylate; cycloalkyl acrylates such as cyclohexyl acrylate, and the like. Examples of the methacrylic acid ester include alkyl methacrylates such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, and butyl methacrylate; cycloalkyl methacrylates such as cyclohexyl methacrylate.

  The polyol is a compound having at least two hydroxyl groups, such as ethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,9-nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,5 -Pentanediol, hydroxypivalic acid neopentyl glycol ester, tricyclodecane dimethylol, 1,4-cyclohexanediol, spiroglycol, tricyclodecane dimethylol, hydrogenated bisphenol A, ethylene oxide-added bisphenol A, propylene glycol Side addition bisphenol A, trimethylolethane, trimethylolpropane, glycerin, 3-methylpentane-1,3,5-triol, pentaerythritol, dipentaerythritol, tripentaerythritol, glucose, etc. can be mentioned.

  As said diisocyanate, various aromatic, aliphatic, or alicyclic diisocyanates can be used, for example, tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 4, , 4-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 3,3-dimethyl-4,4-diphenyl diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4-diphenylmethane diisocyanate, and hydrogenated products thereof Is mentioned.

  The mixing ratio of the component (A) is not particularly limited. By using the component (A), the flexibility of the formed cured layer and the adhesion to the transparent plastic film substrate can be improved. From these points and the viewpoint of the hardness of the cured layer, the blending ratio of the component (A) is, for example, in the range of 15 to 55% by weight with respect to the entire resin component in the cured layer forming material, preferably It is in the range of 25 to 45% by weight. The whole resin component is the total amount of the component (A), the component (B) and the component (C), or, when other resin components are used, the total amount of the three components and the total amount of the resin component The same applies hereinafter.

  Examples of the polyol acrylate as the component (B) include pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, dipentaerythritol hexaacrylate, 1,6-hexanediol acrylate, and the like. Examples of the polyol methacrylate include pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, dipentaerythritol hexamethacrylate, and 1,6-hexanediol methacrylate. These may be used alone or in combination of two or more. Among these, it is preferable that at least one of pentaerythritol triacrylate and pentaerythritol tetraacrylate is included. With such a compound, curling can be more effectively prevented while maintaining sufficient hardness and flexibility. Among these, it is preferable to use a monomer component made of a polymer of pentaerythritol triacrylate and pentaerythritol tetraacrylate and a mixed component containing pentaerythritol triacrylate and pentaerythritol tetraacrylate.

  The blending ratio of (B) is not particularly limited. For example, the blending ratio of the component (B) is preferably in the range of 70 to 180% by weight, more preferably in the range of 100 to 150% by weight with respect to the component (A). When the blending ratio of the component (B) is 180% by weight or less with respect to the component (B), it is possible to effectively prevent curing shrinkage of the formed cured layer, and as a result, the first protection in which the cured layer is formed. Curling of the film can be prevented, and a decrease in flexibility can be prevented.

  Moreover, if the blending ratio of the component (B) is 70% by weight or more of the component (A), the hardness of the formed cured layer can be further improved, and the scratch resistance can be improved. Become. In the laminated optical film of the present invention, the scratch resistance of the cured layer is preferably in the range of 0 to 0.7, more preferably in the range of 0 to 0.5. The measurement of the scratch resistance can be carried out by the measurement method of Examples described later.

  In the component (C), the alkyl group of the (C1) and (C2) is, for example, a linear or branched alkyl group having 1 to 10 carbon atoms, for example, repeating the following general formula (II) Examples include polymers, copolymers, or mixtures thereof containing units.

In the formula (II), R ₄ is hydrogen or a methyl group, R ₅ is —CH ₂ CH ₂ OX, or a group represented by the following general formula (III), and X is hydrogen, or It is an acryloyl group represented by the following general formula (IV). In general formula (III), two Xs may be the same or different.

Examples of the alkyl acrylate corresponding to the general formula (II) include 2,3-dihydroxypropyl acrylate, 2,3-diacryloyloxypropyl acrylate, 2-hydroxy-3-acryloyloxypropyl acrylate, 2-acryloyloxy- Examples include 3-hydroxypropyl acrylate. Examples of the alkyl methacrylate include 2,3-dihydroxypropyl methacrylate, 2,3-diacryloyloxypropyl methacrylate, 2-hydroxy-3-acryloyloxypropyl methacrylate, 2-acryloyloxy-3-hydroxypropyl methacrylate, 2 -Hydroxyethyl acrylate, 2-acryloyloxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-acryloyloxy methacrylate and the like. When the cured layer has the component (C), the occurrence of curling can be more effectively prevented.

  The blending ratio of the component (C) is not particularly limited. For example, the blending ratio of the component (C) is preferably in the range of 25 to 110% by weight, more preferably in the range of 45 to 85% by weight with respect to the component (A). When the blending ratio of the component (C) is 110% by weight or less, the coating property of the cured layer forming material becomes excellent, and when the blending ratio of the component (C) is 25% by weight or more, it is formed. Curing shrinkage of the cured layer can be prevented, and as a result, in the first protective film on which the cured layer is formed, for example, generation can be within 30 mm. The degree of curling is preferably within 20 mm, more preferably within 10 mm.

  The hardened layer H may contain fine particles in order to make its surface structure an uneven structure. This is because the antiglare property can be imparted if the surface structure of the hardened layer is an uneven structure. Examples of the fine particles include inorganic fine particles and organic fine particles. The inorganic fine particles are not particularly limited, and examples thereof include silicon oxide fine particles, titanium oxide fine particles, aluminum oxide fine particles, zinc oxide fine particles, tin oxide fine particles, calcium carbonate fine particles, barium sulfate fine particles, talc fine particles, kaolin fine particles, calcium sulfate fine particles and the like. Is mentioned. The organic fine particles are not particularly limited, and examples thereof include polymethyl methacrylate acrylate resin powder (PMMA fine particles), silicone resin powder, polystyrene resin powder, polycarbonate resin powder, acrylic styrene resin powder, benzoguanamine resin powder, melamine resin powder, Examples include polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, and polyfluorinated ethylene resin powder. One kind of these inorganic fine particles and organic fine particles may be used alone, or two or more kinds may be used in combination.

  The shape of the fine particles is not particularly limited, and may be, for example, a bead-like substantially spherical shape or an irregular shape such as a powder. The weight average particle diameter of the fine particles is, for example, in the range of 1 to 30 μm, and preferably in the range of 2 to 20 μm. The fine particles are preferably substantially spherical, more preferably substantially spherical fine particles having an aspect ratio of 1.5 or less.

  The mixing ratio of the fine particles is not particularly limited and can be set as appropriate. The mixing ratio of the fine particles is, for example, in the range of 2 to 60 parts by weight, and preferably in the range of 1 to 50 parts by weight with respect to 100 parts by weight of the cured layer forming material.

  From the viewpoint of preventing light scattering and interference fringes generated at the interface between the fine particles and the cured layer, it is preferable to reduce the refractive index difference between the fine particles and the cured layer. Such interference fringes are a phenomenon in which reflected light of external light that has entered the cured layer exhibits a rainbow hue. Recently, three-wavelength fluorescent lamps with excellent clarity are frequently used in offices and the like, but interference fringes tend to appear remarkably under the three-wavelength fluorescent lamps. Since the refractive index of the cured layer is generally in the range of 1.4 to 1.6, fine particles having a refractive index close to this refractive index range are preferred. The difference in refractive index between the fine particles and the cured layer is preferably less than 0.05.

  When the difference between the refractive index of the first protective film F1 and the refractive index of the cured layer is d, the d is preferably 0.04 or less. If d is 0.04 or less, interference fringes can be suppressed. The d is more preferably 0.02 or less. The thickness of the said hardened layer is the range of 15-25 micrometers, for example, Preferably, it is the range of 18-23 micrometers. When the thickness is within the predetermined range, the hardness of the hardened layer is sufficient (for example, pencil hardness of 4H or more), and curling can be more effectively prevented. In addition, the thickness of the cured layer when the surface structure of the cured layer is an uneven structure is, for example, in the range of 15 to 35 μm, and more preferably in the range of 20 to 30 μm.

  The cured layer is prepared, for example, by preparing a cured layer forming material in which the three components are dissolved or dispersed in a solvent, and coating the cured layer forming material on the first protective film to form a coating film. It can be formed by curing the film.

  The solvent is not particularly limited, and various solvents can be used. For example, dibutyl ether, dimethoxymethane, dimethoxyethane, diethoxyethane, propylene oxide, 1,4-dioxane, 1,3-dioxolane, 1, 3,5-trioxane, tetrahydrofuran, acetone, methyl ethyl ketone, diethyl ketone, dipropyl ketone, diisobutyl ketone, cyclopentanone, cyclohexanone, methylcyclohexanone, ethyl formate, propyl formate, n-pentyl formate, methyl acetate, ethyl acetate, propionic acid Methyl, ethyl propionate, n-pentyl acetate, acetylacetone, diacetone alcohol, methyl acetoacetate, ethyl acetoacetate, methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, -Butanol, 1-pentanol, 2-methyl-2-butanol, cyclohexanol, isobutyl acetate, methyl isobutyl ketone (MIBK), 2-octanone, 2-pentanone, 2-hexanone, 2-heptanone, 3-heptanone, ethylene Examples include glycol monoethyl ether acetate, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, and propylene glycol monomethyl ether. These may be used alone or in combination of two or more. Further, from the viewpoint of improving the adhesion between the first protective film F1 and the cured layer H, the solvent preferably contains ethyl acetate in a proportion of 20% by weight or more, more preferably 25% by weight. It is to contain ethyl acetate in the ratio of more than%, and it is optimal to contain ethyl acetate in the ratio of 30 to 70 weight% of the whole. If it is 70% by weight or less, the volatilization rate of the solvent can be made appropriate, and coating unevenness and drying unevenness can be effectively prevented. The kind of the solvent used in combination with ethyl acetate is not particularly limited, and examples thereof include butyl acetate, methyl ethyl ketone, ethylene glycol monobutyl ether, and propylene glycol monomethyl ether.

  Various leveling agents can be added to the cured layer forming material. Examples of the leveling agent include a fluorine-based or silicone-based leveling agent, and a silicone-based leveling agent is preferable. Examples of the silicone leveling agent include reactive silicone, polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane. Of these silicone leveling agents, the reactive silicone is particularly preferred. By adding the reactive silicone, slipperiness is imparted to the surface, and scratch resistance is maintained over a long period of time. Further, when the reactive silicone having a hydroxyl group is used, when the antireflection layer (low refractive index layer) containing a siloxane component is formed on the cured layer, the antireflection layer and the cured The adhesion of the layer is improved.

  The blending amount of the leveling agent is, for example, 5 parts by weight or less, preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of the entire resin component.

  If necessary, pigments, fillers, dispersants, plasticizers, UV absorbers, surfactants, antioxidants, thixotropic agents, etc. are added to the cured layer forming material as long as the performance is not impaired. May be. These additives may be used alone or in combination of two or more.

  A conventionally well-known photoinitiator can be used for a cured layer forming material. Examples of the photopolymerization initiator include 2,2-dimethoxy-2-phenylacetophenone, acetophenone, benzophenone, xanthone, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, benzoinpropyl ether, benzyldimethyl Ketal, N, N, N ′, N′-tetramethyl-4,4′-diaminobenzophenone, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, etc. A thioxanthate compound or the like can be used.

  Examples of the method for applying the cured layer forming material on the first protective film include fountain coating, die coating, spin coating, spray coating, gravure coating, roll coating, and bar coating. A construction method can be used.

  A cured layer forming material is applied to form a coating film on the first protective film and cured. Prior to curing, the coating film is preferably dried. Drying may be, for example, natural drying, air drying by blowing air, heat drying, or a combination of these.

The means for curing the coating film of the cured layer forming material is not particularly limited, but ionizing radiation curing is preferable. Various active energies can be used as the means, but ultraviolet rays are preferred. As the energy ray source, for example, a high pressure mercury lamp, a halogen lamp, a xenon lamp, a metal halide lamp, a nitrogen laser, an electron beam accelerator, a radioactive element or the like is preferable. The irradiation amount of the energy ray source is preferably 50 to 5000 mJ / cm ² as an integrated exposure amount at an ultraviolet wavelength of 365 nm. If irradiation amount is 50 mJ / cm < ² > or more, hardening will become more sufficient and the hardness of the hardened layer formed will also become more sufficient. Moreover, if 5000 mJ / cm < ² > or less, coloring of the hardened layer formed can be prevented and transparency can be improved.

  As described above, a cured layer can be formed on the first protective film. In the laminated optical film of the present invention, if the cured layer H is formed using a cured layer forming material containing the component (A), the component (B) and the component (C), the method described above is used. You may manufacture with a manufacturing method other than. The hardness of the hardened layer is, for example, 4H or higher in pencil hardness.

  In FIG. 1, the hardened layer H is a single layer, but the present invention is not limited to this, and may have a multilayer structure in which two or more hardened layers H are laminated.

(Antireflection layer)
In the laminated optical film of the present invention, an antireflection layer (low refractive index layer) L may be disposed on the cured layer. An example of the laminated optical film of the present invention having the antireflection layer L is shown in FIG. As shown in the drawing, the laminated optical film of this example has a configuration in which a cured layer H is formed on one main surface of the first protective film, and an antireflection layer L is formed on the cured layer H. . When light strikes an object, it repeats the phenomenon of reflection at the interface, absorption inside, and scattering, and passes through the back of the object.

  For example, when a laminated optical film having a hardened layer applied to an image display device such as a liquid layer display device is mounted, one of the factors that lower the image visibility is the reflection of light at the interface between the air and the hardened layer. The antireflection layer reduces the surface reflection. In FIG. 2, the laminated optical film has a cured layer H and an antireflection layer L each of which is a single layer. However, the present invention is not limited to this, and the cured layer H and the antireflection layer L are each composed of a single layer. A multi-layer structure in which two or more layers are laminated may be used.

  The antireflection layer is an optical thin film in which thickness and refractive index are strictly controlled, or a laminate of two or more optical thin films. The antireflection layer exhibits an antireflection function by canceling out the reversed phases of incident light and reflected light using the interference effect of light. The wavelength region of visible light that exhibits the antireflection function is, for example, 380 to 780 nm, and the wavelength region with particularly high visibility is in the range of 450 to 650 nm, and the reflectance at 550 nm, which is the central wavelength, is minimized. Thus, it is preferable to design the antireflection layer.

  In designing the antireflection layer based on the light interference effect, as a means for improving the interference effect, for example, there is a method of increasing the difference in refractive index between the antireflection layer and the cured layer. In general, in a multilayer antireflection layer having a structure in which two to five optical thin films (thin films whose thickness and refractive index are strictly controlled) are laminated, a plurality of components having different refractive indexes are formed in a predetermined thickness. Thus, the degree of freedom in optical design of the antireflection layer is increased, the antireflection effect can be further improved, and the spectral reflection characteristics can be made uniform (flat) in the visible light region. Since the optical thin film requires high thickness accuracy, each layer is generally formed by a dry method such as vacuum evaporation, sputtering, or CVD.

  The multilayer antireflection layer has a two-layer structure in which a low refractive index silicon oxide layer (refractive index: about 1.45) is laminated on a high refractive index titanium oxide layer (refractive index: about 1.8). More preferably, a four-layer structure in which a silicon oxide layer is laminated on a titanium oxide layer, a titanium oxide layer is laminated on the silicon oxide layer, and a silicon oxide layer is laminated on the titanium oxide layer. belongs to. By forming these two-layer antireflection layers or four-layer antireflection layers, it is possible to uniformly reduce reflection in the visible light wavelength region (for example, a range of 380 to 780 nm).

  Further, the antireflection effect can be exhibited also by forming a single-layer optical thin film (antireflection layer) on the cured layer. In general, for forming the single-layer antireflection layer, for example, a wet method such as phanten coating, die coating, spin coating, spray coating, gravure coating, roll coating, or bar coating is employed.

  The material for forming the single-layer antireflection layer is, for example, a resin material such as an ultraviolet curable acrylic resin, a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in the resin, tetraethoxysilane, titanium tetraethoxide, or the like. Examples include sol-gel materials using metal alkoxides. Moreover, in the said forming material, what contains a fluorine group is preferable for imparting antifouling properties to the surface. In the forming material, for reasons such as scratch resistance, a forming material having a high inorganic component content is preferable, and the sol-gel material is more preferable. The sol-gel material can be used after partial condensation.

  As the antireflection layer (low refractive index layer), a siloxane oligomer having a number average molecular weight of 500 to 10,000 in terms of ethylene glycol and a fluorine compound having a polystyrene equivalent number average molecular weight of 5000 or more and having a fluoroalkyl structure and a polysiloxane structure And the like (a material described in JP-A No. 2004-167827) are preferable because they can achieve both scratch resistance and low reflection.

  The antireflection layer (low refractive index layer) may contain an inorganic sol in order to improve the film strength. The inorganic sol is not particularly limited, and examples thereof include inorganic sols such as silica, alumina, and magnesium fluoride. Among these, silica sol is preferable. The blending ratio of the inorganic sol is, for example, in the range of 10 to 80 parts by weight with respect to 100 parts by weight of the total solid content of the antireflection layer forming material. The particle size of the inorganic fine particles in the inorganic sol is preferably in the range of 2 to 50 nm, and more preferably in the range of 5 to 30 nm.

  The material for forming the antireflection layer preferably contains hollow spherical silicon oxide ultrafine particles. The silicon oxide ultrafine particles preferably have an average particle size of about 5 to 300 nm, and more preferably in the range of 10 to 200 nm. The silicon oxide ultrafine particles are hollow spheres having cavities formed in the outer shells having pores, and the cavities include at least one of a solvent and a gas at the time of preparing the silicon oxide ultrafine particles. It is. Moreover, it is preferable that the precursor substance for forming the said cavity of the said silicon oxide ultrafine particle remains in the said cavity. The thickness of the outer shell is preferably in the range of about 1 to 50 nm and in the range of about 1/50 to 1/5 of the average particle diameter of the silicon oxide ultrafine particles. The outer shell is preferably formed from a plurality of coating layers. Further, in the silicon oxide ultrafine particles, it is preferable that the pores are closed and the cavity is sealed by the outer shell. This is because the porous or voids of the silicon oxide ultrafine particles are maintained in the antireflection layer, and the refractive index of the antireflection layer can be further reduced. As a method for producing such hollow and spherical silicon oxide ultrafine particles, for example, the method for producing silica-based fine particles disclosed in JP-A-2000-233611 is suitably employed.

  The temperature of drying and curing when forming the antireflection layer (low refractive index layer) is not particularly limited, and is, for example, in the range of 60 to 150 ° C, preferably in the range of 70 to 130 ° C. The drying and curing time is, for example, in the range of 1 to 30 minutes, and when considering productivity, the range of 1 to 10 minutes is preferable. Further, after the drying and curing, a heat treatment is further performed to obtain a high-hardness laminated optical film having an antireflection layer. The temperature of the heat treatment is not particularly limited, and is, for example, in the range of 40 to 130 ° C., preferably in the range of 50 to 100 ° C. The heat treatment time is not particularly limited, and for example, 1 minute to From the viewpoint of improving scratch resistance for 100 hours, it is more preferable to carry out for 10 hours or more. The heat treatment can be performed by a method using a hot plate, an oven, a belt furnace, or the like.

  When a laminated optical film having an antireflection layer is attached to an image display device such as a liquid crystal display device, the antireflection layer is likely to be the outermost layer, and is thus easily contaminated by the external environment. Antireflection layers are more prone to contamination than mere transparent plates.For example, surface reflectance changes due to adhesion of contaminants such as fingerprints, hand dirt, sweat, and hairdressing materials, and the deposits appear white. The displayed content may be unclear. In order to prevent the adhesion of contaminants and improve the ease of removing the adhered contaminants, a contamination prevention layer formed of a fluorine group-containing silane compound or a fluorine group-containing organic compound is laminated on the antireflection layer. It is preferable to do.

(Lamination method of film)
In the laminated optical film of the present invention, the method of laminating the polarizer P, the first protective film F1, and the second protective film F2 is not particularly limited, but an adhesive is used from the viewpoint of workability and light utilization efficiency. Thus, it is desirable to laminate each layer without air gaps. When using an adhesive agent, the kind in particular is not restrict | limited, A various thing can be used.

(adhesive)
In particular, in the present invention, the adhesive layer between the polarizer P and the second protective film F2 contains, as an adhesive, a polyvinyl alcohol resin, a crosslinking agent, and a metal compound colloid having an average particle diameter of 1 to 100 nm. It is preferable to use a resin solution and a metal compound colloid formed of an adhesive compounded at a ratio of 200 parts by weight or less with respect to 100 parts by weight of the polyvinyl alcohol resin. In the present invention, as described above, the absolute value of the photoelastic coefficient of the second protective film F2 is 1.0 × 10 ⁻¹¹ m ² / N or less from the viewpoint of suppressing the change in optical characteristics under the heating environment. However, a cellulose-based resin such as triacetyl cellulose, which is generally widely used as a polarizer protective film, has a photoelastic coefficient larger than the above range and cannot be said to be suitable as a second protective film. On the other hand, a film made of a resin having a small photoelastic coefficient such as the above-mentioned cyclic polyolefin resin (norbornene resin), (meth) acrylic resin, or polystyrene resin adheres to the polarizer through an adhesive layer. When the film is dried after being subjected to the process, uneven defects (knicks) tend to occur. In particular, when the laminated optical film of the present invention is used in an image display device such as a liquid crystal display device, the visibility of the image tends to be affected, for example, the nick portion appears to be out of light.

  Examples of the polyvinyl alcohol resin used for the adhesive include a polyvinyl alcohol resin and a polyvinyl alcohol resin having an acetoacetyl group. A polyvinyl alcohol resin having an acetoacetyl group is a polyvinyl alcohol-based adhesive having a highly reactive functional group, and is preferable because durability of the polarizing plate is improved.

  Polyvinyl alcohol resin is polyvinyl alcohol obtained by saponifying polyvinyl acetate; a derivative thereof; a saponified product of a copolymer of vinyl acetate and a monomer having copolymerizability; Examples thereof include modified polyvinyl alcohols that have been converted into ethers, ethers, grafts, or phosphoric esters. Examples of the monomer include unsaturated carboxylic acids such as (anhydrous) maleic acid, fumaric acid, crotonic acid, itaconic acid, (meth) acrylic acid, and esters thereof; α-olefins such as ethylene and propylene, (meth) Examples include allyl sulfonic acid (soda), sulfonic acid soda (monoalkyl malate), disulfonic acid soda alkyl maleate, N-methylol acrylamide, acrylamide alkyl sulfonic acid alkali salt, N-vinyl pyrrolidone, N-vinyl pyrrolidone derivatives, and the like. . These polyvinyl alcohol resins can be used alone or in combination of two or more.

  The polyvinyl alcohol-based resin is not particularly limited, but from the viewpoint of adhesiveness, the average degree of polymerization is about 100 to 5000, preferably 1000 to 4000, the average saponification degree is about 85 to 100 mol%, preferably 90 to 100 mol%. It is.

  A polyvinyl alcohol-based resin containing an acetoacetyl group is obtained by reacting a polyvinyl alcohol-based resin with diketene by a known method. For example, a method in which a polyvinyl alcohol resin is dispersed in a solvent such as acetic acid and diketene is added thereto. A polyvinyl alcohol resin is previously dissolved in a solvent such as dimethylformamide or dioxane, and diketene is added thereto. And the like. Moreover, the method of making diketene gas or liquid diketene contact directly to polyvinyl alcohol is mentioned.

  The degree of acetoacetylation of the polyvinyl alcohol resin containing an acetoacetyl group is not particularly limited as long as it is 0.1 mol% or more. If it is less than 0.1 mol%, the water resistance of the adhesive layer tends to be insufficient. The degree of acetoacetylation is preferably about 0.1 to 40 mol%, more preferably 1 to 20 mol%, and particularly preferably 2 to 7 mol%. If the degree of acetoacetylation exceeds 40 mol%, the effect of improving water resistance may not be sufficiently obtained. The degree of acetoacetylation can be quantified by NMR.

  As a crosslinking agent, what is used for the polyvinyl alcohol-type adhesive agent can be especially used without a restriction | limiting. A compound having at least two functional groups having reactivity with the polyvinyl alcohol resin can be used. For example, alkylene diamines having two alkylene groups and two amino groups such as ethylene diamine, triethylene diamine and hexamethylene diamine; tolylene diisocyanate, hydrogenated tolylene diisocyanate, trimethylolpropane tolylene diisocyanate adduct, triphenylmethane triisocyanate, methylene bis (Isocyanates such as 4-phenylmethane triisocyanate, isophorone diisocyanate and their ketoxime block product or phenol block product; ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerin di or triglycidyl ether, 1,6-hexane Diol diglycidyl ether, trimethylolpropane triglycidyl ether, diglycidyl Epoxys such as aniline and diglycidylamine; monoaldehydes such as formaldehyde, acetaldehyde, propionaldehyde, and butyraldehyde; Amino-formaldehyde resins such as methylol urea, methylol melamine, alkylated methylol urea, alkylated methylolated melamine, acetoguanamine, benzoguanamine and formaldehyde condensates; further sodium, potassium, magnesium, calcium, aluminum, iron, Examples thereof include divalent metals such as nickel or salts of trivalent metals and oxides thereof, among which amino-formaldehyde resins and dialaldehydes. S is preferably an amino -.. Is preferably a compound having a methylol group as a formaldehyde resin, the dialdehydes are preferred glyoxal is inter alia a compound having a methylol group, methylol melamine is particularly preferred.

  The amount of the crosslinking agent can be appropriately designed according to the type of the polyvinyl alcohol resin in the adhesive and the like, but is usually about 10 to 60 parts by weight, preferably 20 with respect to 100 parts by weight of the polyvinyl alcohol resin. ~ 50 parts by weight. In such a range, good adhesiveness can be obtained.

  In order to improve durability, it is preferable to use a polyvinyl alcohol-based resin containing an acetoacetyl group. Also in this case, it is preferable to use the crosslinking agent in the range of 10 to 60 parts by weight, and further 20 to 50 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin in the adhesive. When the amount of the crosslinking agent is too large, the reaction of the crosslinking agent proceeds in a short time and the adhesive tends to gel. As a result, the usable time (pot life) as an adhesive becomes extremely short, and industrial use may be difficult. From this point of view, the blending amount of the crosslinking agent is used in the above blending amount. However, since the resin solution of the present invention contains the metal compound colloid, the blending amount of the crosslinking agent is large as described above. Even if it exists, it can be used with good stability.

  The metal compound colloid is one in which fine particles are dispersed in a dispersion medium, and is electrostatically stabilized due to mutual repulsion of the same kind of charge of the fine particles, and has permanent stability. The average particle diameter of the metal compound colloid (fine particles) is 1 to 100 nm. When the average particle diameter of the colloid is within the above range, the metal compound can be dispersed substantially uniformly in the adhesive layer, the adhesion can be ensured, and the nick can be suppressed. The range of the average particle diameter is considerably smaller than the wavelength range of visible light, and even if the transmitted light is scattered by the metal compound in the formed adhesive layer, the polarization characteristics are not adversely affected. The average particle size of the metal compound colloid is preferably 1 to 100 nm, more preferably 1 to 50 nm.

  Various types of metal compound colloids can be used. For example, as a metal compound colloid, colloids of metal oxides such as alumina, silica, zirconia, titania, aluminum silicate, calcium carbonate and magnesium silicate; colloids of metal salts such as zinc carbonate, barium carbonate and calcium phosphate; celite, Examples thereof include colloids of minerals such as talc, clay and kaolin.

  The metal compound colloid is dispersed in a dispersion medium and exists in a state of a colloid solution. The dispersion medium is mainly water. In addition to water, other dispersion media such as alcohols can also be used. The solid content concentration of the metal compound colloid in the colloid solution is not particularly limited, but is generally about 1 to 50% by weight, and more preferably 1 to 30% by weight. In addition, as the metal compound colloid, those containing an acid such as nitric acid, hydrochloric acid, and acetic acid as a stabilizer can be used.

  Metal compound colloids are electrostatically stabilized and can be classified into those having a positive charge and those having a negative charge. Metal compound colloids are non-conductive materials. Positive charge and negative charge are distinguished by the charge state of the colloidal surface charge in the solution after the adhesive preparation. The charge of the metal compound colloid can be confirmed, for example, by measuring the zeta potential with a zeta potential measuring machine. The surface charge of a metal compound colloid generally varies with pH. Therefore, the charge in the state of the colloidal solution of the present application is affected by the pH of the adjusted adhesive solution. The pH of the adhesive solution is usually set in the range of 2 to 6, preferably 2.5 to 5, more preferably 3 to 5, and further 3.5 to 4.5. In the present invention, a metal compound colloid having a positive charge has a greater effect of suppressing the occurrence of nicks than a metal compound colloid having a negative charge. Examples of positively charged metal compound colloids include alumina colloids and titania colloids. Among these, alumina colloid is particularly preferable.

  The metal compound colloid is preferably blended at a ratio of 200 parts by weight or less (converted value of solid content) with respect to 100 parts by weight of the polyvinyl alcohol resin. By making the compounding ratio of the genus compound colloid within the above range, it is possible to suppress the occurrence of nicks while ensuring the adhesion between the polarizer and the protective film. The compounding ratio of the metal compound colloid is preferably 10 to 200 parts by weight, more preferably 20 to 175 parts by weight, and further preferably 30 to 150 parts by weight. If the blending ratio of the metal compound colloid with respect to the polyvinyl alcohol resin is excessive, the adhesiveness may be inferior. If the blending ratio of the metal compound colloid is small, the effect of suppressing the occurrence of nicks may not be sufficiently obtained.

  The adhesive is a resin solution containing a polyvinyl alcohol resin, a crosslinking agent, and a metal compound colloid having an average particle diameter of 1 to 100 nm, and is usually used as an aqueous solution. The concentration of the resin solution is not particularly limited, but is 0.1 to 15% by weight, preferably 0.5 to 10% by weight in consideration of coating properties and storage stability.

  The viscosity of the resin solution as the adhesive is not particularly limited, but those in the range of 1 to 50 mPa · s can be suitably used. In making a polarizing plate, it is common that the occurrence of nicks increases as the viscosity of the adhesive decreases. However, by setting the adhesive to the composition as described above, regardless of the viscosity of the resin solution, 1 Even in a low viscosity range such as ˜20 mPa · s, the occurrence of nicks can be suppressed. A polyvinyl alcohol resin containing an acetoacetyl group cannot be increased in polymerization degree compared to a general polyvinyl alcohol resin and has been used at a low viscosity as described above. Even when a polyvinyl alcohol-based resin containing an acetyl group is used, the occurrence of nicks can be suppressed because the resin solution has a low viscosity.

  The method for preparing the resin solution as the adhesive is not particularly limited. Usually, a resin solution is prepared by mixing a polyvinyl alcohol-based resin and a cross-linking agent and blending a metal compound colloid into an appropriate concentration. In addition, when a polyvinyl alcohol resin containing an acetoacetyl group is used as the polyvinyl alcohol resin or when the amount of the crosslinking agent is large, the polyvinyl alcohol resin and the metal are considered in consideration of the stability of the solution. After mixing the compound colloid, the cross-linking agent can be mixed in consideration of the use time of the resulting resin solution. In addition, the density | concentration of the resin solution which is an adhesive agent for polarizing plates can also be adjusted suitably after preparing a resin solution.

  The adhesive further includes a coupling agent such as a silane coupling agent and a titanium coupling agent, various tackifiers, an ultraviolet absorber, an antioxidant, a heat stabilizer, a hydrolysis stabilizer, and the like. Can also be blended. Moreover, although the metal compound colloid in this application is a nonelectroconductive material, it can also contain the fine particle of an electroconductive substance.

(Lamination of polarizer and protective film)
Application | coating of the adhesive agent when laminating | stacking a polarizer and a protective film may be performed to any of a protective film and a polarizer, and may be performed to both. It is preferable to apply the adhesive so that the thickness of the adhesive layer after drying is about 10 to 300 nm. The thickness of the adhesive layer is more preferably from 10 to 200 nm, and even more preferably from 20 to 150 nm, from the viewpoint of obtaining a uniform in-plane thickness and sufficient adhesive strength. As described above, the thickness of the adhesive layer is preferably designed to be larger than the average particle diameter of the metal compound colloid contained in the polarizing plate adhesive.

  The method of adjusting the thickness of the adhesive layer is not particularly limited, and examples thereof include a method of adjusting the solid content concentration of the adhesive solution and an adhesive application device. The method for measuring the thickness of the adhesive layer is not particularly limited, but cross-sectional observation measurement using SEM (Scanning Electron Microscopy) or TEM (Transmission Electron Microscopy) is preferably used. The application operation of the adhesive is not particularly limited, and various means such as a roll method, a spray method, and an immersion method can be employed.

  After applying the adhesive, the polarizer and the protective film are bonded together using a roll laminator or the like. In the method for producing a polarizing plate of the present invention, as described above, the moisture content of the polarizer used in the bonding step is preferably 10 to 30% by weight, and preferably 12 to 28% by weight. More preferably, it is more preferably 16 to 25% by weight. By setting the moisture content within the above range, the degree of polarization can be kept high, and the occurrence of nicks and unevenness in appearance can be prevented.

  Furthermore, it is preferable to dry at an appropriate drying temperature after bonding protective films on both sides of the polarizer. From the viewpoint of optical properties, the drying temperature is preferably 90 ° C. or lower, more preferably 85 ° C. or lower, and further preferably 80 ° C. or lower. Moreover, although there is no minimum in drying temperature, when the efficiency and practicality of a process are considered, it is preferable that it is 50 degreeC or more. In addition, the drying temperature can be increased in stages within the above temperature range.

  The surface of the protective film that adheres to the polarizer can be subjected to an easy adhesion treatment. Examples of the easy adhesion treatment include dry treatment such as plasma treatment and corona treatment, chemical treatment such as alkali treatment (saponification treatment), and coating treatment for forming an easy adhesion layer. Among these, a coating treatment or an alkali treatment for forming an adhesive layer is preferable. Various easily adhesive materials such as polyol resin, polycarboxylic acid resin, and polyester resin can be used for forming the easily adhesive layer. Note that the thickness of the easy-adhesion layer is usually about 0.001 to 10 μm, more preferably about 0.001 to 5 μm, and particularly preferably about 0.001 to 1 μm.

  In manufacturing the laminated optical film of the present invention, the first protective film and the polarizer may be laminated after the cured layer H is formed on the first protective film. The cured layer H may be formed on the first protective film after laminating the film and the polarizer.

  In the case where the cured layer H is formed before the first protective film and the polarizer are laminated, in order to prevent the occurrence of curling accompanying the formation of the cured layer H, the other main surface, that is, the main adhesive to the polarizer. Solvent treatment can also be performed on the surface. The solvent treatment can be carried out by contacting a solvent capable of dissolving the transparent plastic film substrate or a solvent capable of swelling. Curling can be prevented by applying a force for curling to the opposite main surface side by the solvent treatment, thereby offsetting the force for curling by forming the cured layer. Further, instead of the solvent treatment or in addition to the solvent treatment, the occurrence of curling can be prevented by forming a transparent resin layer. Examples of such a transparent resin layer include a layer mainly composed of a thermoplastic resin, a radiation curable resin, a thermosetting resin, and other reactive resins. Among these, a layer mainly composed of a thermoplastic resin is particularly preferable.

(Other optical layers)
The laminated optical film of the present invention has other optical layers in addition to the cured layer H, the first protective film F1, the polarizer P, the second protective film F2, and the adhesive for laminating them. Also good. In particular, as shown in FIG. 3, those having the optical compensation layer R on the main surface of the second protective film F2 on which the polarizer P is not laminated can be suitably used as the optical compensation polarizing plate. As the optical compensation layer, a retardation plate that converts the polarization state of light mainly by birefringence of a polymer or a liquid crystal compound is used.

(Phase difference plate)
Examples of the retardation plate include a birefringent film obtained by uniaxially or biaxially stretching a polymer material, a liquid crystal polymer alignment film, and a liquid crystal polymer alignment layer supported by a film. The thickness of the retardation plate is not particularly limited, but is generally about 20 to 150 μm.

  Examples of the polymer material include polyvinyl alcohol, polyvinyl butyral, polymethyl vinyl ether, polyhydroxyethyl acrylate, hydroxyethyl cellulose, hydroxypropyl cellulose, methyl cellulose, polycarbonate, polyarylate, polysulfone, polyethylene terephthalate, polyethylene naphthalate, polyether sulfone, Polyphenylene sulfide, polyphenylene oxide, polyallylsulfone, polyamide, polyimide, polyolefin, polyvinyl chloride, cellulose resin, cyclic polyolefin resin (norbornene resin), or binary or ternary copolymers thereof, Examples include graft copolymers and blends. These polymer materials become an oriented product (stretched film) by stretching or the like.

  Examples of the liquid crystalline polymer include various main chain types and side chain types in which a conjugated linear atomic group (mesogen) imparting liquid crystal alignment is introduced into the main chain or side chain of the polymer. It is done. Specific examples of main-chain liquid crystalline polymers include, for example, nematic alignment polyester liquid crystalline polymers, discotic polymers, and cholesteric liquid crystalline polymers having a structure in which mesogenic groups are bonded at a spacer portion that imparts flexibility. Can be mentioned. Specific examples of the side chain type liquid crystalline polymer include polysiloxane, polyacrylate, polymethacrylate, or polymalonate as a main chain skeleton, and a nematic alignment imparting paraffin through a spacer portion composed of a conjugated atomic group as a side chain. Examples thereof include those having a mesogen moiety composed of a substituted cyclic compound unit. These liquid crystalline polymers include, for example, a solution of a liquid crystalline polymer on an alignment treatment surface such as a surface of a thin film such as polyimide or polyvinyl alcohol formed on a glass plate, or an oblique deposition of silicon oxide. It is performed by developing and heat-treating.

  The retardation plate may have an appropriate retardation according to the purpose of use, such as those for the purpose of compensating for coloring, viewing angle, etc. due to birefringence of various wavelength plates and liquid crystal layers. It may be a laminate in which retardation plates are stacked to control optical characteristics such as retardation.

  The retardation plate has a relationship of nx = ny> nz, nx> ny> nz, nx> ny = nz, nx> nz> ny, nz = nx> ny, nz> nx> ny, nz> nx = ny. What is satisfactory is selected and used according to various applications. Note that ny = nz includes not only the case where ny and nz are completely the same, but also the case where ny and nz are substantially the same.

  In addition, a liquid crystal polymer alignment layer, particularly an optically anisotropic layer composed of a discotic liquid crystal polymer gradient alignment layer, is supported by a triacetyl cellulose film in order to achieve a wide viewing angle with good visibility. A plate or the like can also be used.

  In general, as a retardation plate used as an optical compensation layer in an optical compensation polarizing plate, a viewpoint of suppressing changes in optical properties and display unevenness (thermal unevenness) under severe conditions such as heating and humidification Therefore, those having a small photoelastic coefficient are preferred. Especially in the case of large liquid crystal display devices such as televisions, the dimensional change under heating and humidification environment is relatively large when compared with mobile applications such as mobile phones. Since the change in phase difference tends to be large, those having a small photoelastic coefficient are preferred.

  On the other hand, polymers with a small photoelastic coefficient are difficult to control three-dimensional birefringence, lack of variations in wavelength dispersion of retardation, and the types of liquid crystal cells that can exhibit sufficient optical compensation are limited. There was a case. In mobile applications, a polymer having a low photoelastic coefficient is preferably used for the optical compensation layer because a higher durability tends to be desired, but the photoelastic coefficient and orientation birefringence have a strong correlation, In general, a polymer having a small photoelastic coefficient tends to have low birefringence. Therefore, when trying to obtain a desired phase difference with a film having a small photoelastic coefficient, it may be necessary to increase the film thickness as compared with a film having a large photoelastic coefficient. The use of was sometimes restricted.

From such a viewpoint, an optical compensation polarizing plate having high durability without being influenced by the photoelastic coefficient of the optical compensation layer, or a laminated optical film that can constitute the optical compensation polarizing plate is desired. According to the laminated optical film of the present invention, even when a retardation plate having a relatively large photoelastic coefficient, for example, exceeding 1.0 × 10 ⁻¹¹ m ² / N, is used under heating or humidification. It has been found that the optical characteristics change under severe conditions and the occurrence of display unevenness (heat unevenness) are suppressed.

  As described above, the reason why the durability of the polarizing plate is improved by the configuration of the present invention is not clear, but by providing the cured layer H, the dimensional change due to heating / humidification of the first protective film F1 is suppressed, and accordingly. In addition, since the dimensional change of the polarizer P and the second protective film F2 is also suppressed, the stress generated at the interface between the second protective film F2 and the optical compensation layer R is reduced, and as a result, the optical compensation layer (retardation plate) Even when the photoelastic coefficient of R is large, it is considered that the change in the retardation value is suppressed.

  Compared with (meth) acrylic resins and cyclic polyolefin resins, those having a relatively large photoelastic coefficient include cellulose resins, polyester resins, polyethersulfone resins, polysulfone resins, polycarbonate resins, Examples thereof include polyamide resins, polyimide resins, polyarylate resins, polystyrene resins, and liquid crystalline polymers.

As an example of an embodiment in which a change in optical properties under heating and humidification can be suppressed by the laminated optical film of the present invention, for example, a co-polymer containing a polycarbonate having a fluorene skeleton disclosed in WO00 / 26705 International Publication Pamphlet or the like. A laminated optical film using a retardation film made of a polymer can be mentioned. Such a polymer has the property of having higher retardation as the wavelength is longer, and can be suitably used for a broadband circularly polarizing plate or the like, but has a photoelastic coefficient (depending on the copolymerization ratio) of approximately 3 × 10 ^−11. Since it was larger than m ² / N, its application range was limited. By applying this to the laminated optical film of the present invention, an optical compensation polarizing plate with little heat unevenness due to heating can be obtained.

  In addition, said example is only what disclosed the example of the application example of the laminated optical film of this invention, and does not limit the scope of the present invention to this example.

  In addition to the optical compensation layer, examples of the optical layer suitably used for the laminated optical film of the present invention include a brightness enhancement film and a reflective layer.

(Brightness enhancement film)
The brightness enhancement film reflects the linearly polarized light with a predetermined polarization axis or the circularly polarized light in a predetermined direction when natural light is incident due to a backlight of a liquid crystal display device or the like or reflection from the back side, and transmits other light. In the case where a brightness enhancement film is laminated with a polarizing plate, light from a light source such as a backlight is incident to obtain transmitted light in a predetermined polarization state, and light other than the predetermined polarization state is reflected without being transmitted. . The light reflected on the surface of the brightness enhancement film is further inverted through a reflective layer or the like provided behind the brightness enhancement film and re-incident on the brightness enhancement film, and part or all of the light is transmitted as light having a predetermined polarization state. Luminance can be improved by increasing the amount of light transmitted through the enhancement film and increasing the amount of light that can be used for image display and the like by supplying polarized light that is difficult to absorb into the polarizer. A polarizing plate obtained by bonding a polarizing plate and a brightness enhancement film is often used by being provided on the backlight side of a liquid crystal cell. However, as disclosed in WO 2006/038404, an international pamphlet is used. It can also be provided on the viewing side.

  As a brightness enhancement film, for example, a multi-layer thin film of dielectric material or a multi-layer laminate of thin film films having different refractive index anisotropy, which shows a characteristic of transmitting linearly polarized light with a predetermined polarization axis and reflecting other light , Such as an oriented film of cholesteric liquid crystalline polymer or an oriented liquid crystal layer supported on a film substrate, which reflects either left-handed or right-handed circularly polarized light and transmits other light For example, an appropriate one can be used.

(Reflective layer)
By providing a reflective layer on the laminated optical film of the present invention, a reflective polarizing plate can be obtained. The reflective polarizing plate is used to form a liquid crystal display device or the like that reflects incident light from the viewing side (display side) on the polarizing plate, and can eliminate the incorporation of a light source such as a backlight. Thus, the liquid crystal display device can be easily thinned. The reflective polarizing plate can be formed by an appropriate method such as attaching a reflective layer made of metal or the like to one side of the polarizing plate through a transparent protective layer or the like as necessary.

  The semi-transmissive polarizing plate can be obtained by using a semi-transmissive reflective layer such as a half mirror that reflects and transmits light with the reflective layer. A transflective polarizing plate is usually provided on the back side (backlight side) of a liquid crystal cell, and reflects incident light from the viewing side (display side) when a liquid crystal display device is used in a relatively bright atmosphere. In a relatively dark atmosphere, a liquid crystal display device of a type that displays an image using a built-in light source such as a backlight built in the back side of the transflective polarizing plate can be formed. In other words, the transflective polarizing plate is useful for forming a liquid crystal display device of a type that can save the energy of using a light source such as a backlight in a bright atmosphere and can be used with a built-in light source even in a relatively dark atmosphere. It is.

(Lamination of optical layer)
Optical layers such as an optical compensation layer, a brightness enhancement film, and a reflective layer can be formed by sequentially laminating them in the manufacturing process of a liquid crystal display device or the like. Further, there is an advantage that the manufacturing process of the liquid crystal display device and the like can be improved because of excellent quality stability and assembly work. For the lamination, an appropriate adhesive means such as an adhesive layer can be used. In the formation of the laminated optical film, the optical axes thereof can be set at an appropriate arrangement angle in accordance with the target retardation characteristics and the like.

  The laminated optical film described above can also be provided with an adhesive layer for adhering to other members such as a liquid crystal cell. The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited. For example, an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyamide, polyether, fluorine-based or rubber-based polymer is appropriately selected. Can be used. In particular, those having excellent optical transparency, such as an acrylic pressure-sensitive adhesive, exhibiting appropriate wettability, cohesiveness, and adhesive pressure-sensitive adhesive properties, and having excellent weather resistance, heat resistance and the like can be preferably used.

  In addition to the above, from the viewpoints of prevention of foaming and peeling phenomenon due to moisture absorption, deterioration of optical characteristics due to thermal expansion difference and the like, prevention of warpage of liquid crystal cells, and formation of liquid crystal display devices with high quality and excellent durability. An adhesive layer having a low moisture absorption rate and excellent heat resistance is preferred.

  The adhesive layer is, for example, natural or synthetic resins, in particular, tackifier resins, fillers or pigments made of glass fibers, glass beads, metal powders, other inorganic powders, colorants, antioxidants, etc. It may contain an additive to be added to the adhesive layer. Moreover, the adhesion layer etc. which contain microparticles | fine-particles and show light diffusibility may be sufficient.

  The attachment of the adhesive layer to one or both sides of the laminated optical film and other optical layers can be performed by an appropriate method. For example, a pressure sensitive adhesive solution of about 10 to 40% by weight in which a base polymer or a composition thereof is dissolved or dispersed in a solvent composed of a suitable solvent alone or a mixture such as toluene and ethyl acetate is prepared. A method of attaching it directly on a polarizing plate or an optical film by an appropriate development method such as a casting method or a coating method, or forming an adhesive layer on a separator according to the above and laminating it to a laminated optical film or other optical For example, a method of transferring onto the layer may be mentioned.

  The pressure-sensitive adhesive layer can be provided on one side or both sides of a laminated optical film or other optical layers as a superposed layer of different compositions or types. Moreover, when providing in both surfaces, it can also be set as the adhesion layers of a different composition, a kind, thickness, etc. in the front and back of a polarizing plate or an optical film. The thickness of the pressure-sensitive adhesive layer can be appropriately determined according to the purpose of use and adhesive strength, and is generally 1 to 500 μm, preferably 5 to 200 μm, and particularly preferably 10 to 100 μm.

  It is preferable to cover the exposed surface of the adhesive layer with a separator temporarily attached for the purpose of preventing contamination until it is practically used. Thereby, it can prevent contacting an adhesion layer in the usual handling state. As the separator, except for the above thickness conditions, for example, a suitable thin leaf body such as a plastic film, rubber sheet, paper, cloth, non-woven fabric, net, foam sheet, metal foil, laminate thereof, and the like, silicone type or Appropriate conventional ones such as those coated with an appropriate release agent such as long-chain alkyl, fluorine-based, or molybdenum sulfide can be used.

  In the present invention, each layer such as a polarizer, a protective film, other optical layers, an adhesive, and an adhesive layer forming the above laminated optical film includes, for example, a salicylic acid ester compound, a benzophenol compound, and a benzotriazole compound. Alternatively, those having an ultraviolet absorbing ability by a method such as treatment with an ultraviolet absorber such as a cyanoacrylate compound or a nickel complex salt compound may be used.

(Liquid crystal display device)
The laminated optical film of the present invention can be preferably used for forming various devices such as a liquid crystal display device. The liquid crystal display device can be formed according to the conventional method. That is, a liquid crystal display device is generally formed by appropriately assembling components such as a liquid crystal cell, a polarizing plate or an optical film, and an illumination system as necessary, and incorporating a drive circuit. There is no limitation in particular except the point which uses the polarizing plate or optical film by invention, According to the past. As the liquid crystal cell, any type of liquid crystal cell such as a TN type, STN type, or π type can be used.

  An appropriate liquid crystal display device such as a liquid crystal display device in which a polarizing plate or an optical film is disposed on one side or both sides of a liquid crystal cell, or a backlight or a reflecting plate used in an illumination system can be formed. In that case, the laminated optical film by this invention can be installed in the one side or both sides of a liquid crystal cell. When providing a polarizing plate or an optical film on both sides, they may be the same or different. Furthermore, when forming a liquid crystal display device, for example, a single layer or a suitable part such as a diffusing plate, an antiglare layer, an antireflection film, a protective plate, a prism array, a lens array sheet, a light diffusing plate, a backlight, etc. Two or more layers can be arranged.

  In particular, since the laminated optical film of the present invention has a cured layer on the surface, it can be suitably used as a viewing side polarizing plate of a liquid crystal display device. Use of the laminated optical film of the present invention for the viewing side polarizing plate is preferable in that it has scratch resistance without a cover plate made of glass or plastic.

(Organic EL display device)
Next, an organic electroluminescence device (organic EL display device) will be described. Generally, in an organic EL display device, a transparent electrode, an organic light emitting layer, and a metal electrode are sequentially laminated on a transparent substrate to form a light emitter (organic electroluminescent light emitter). Here, the organic light emitting layer is a laminate of various organic thin films, for example, a laminate of a hole injection layer made of a triphenylamine derivative and the like and a light emitting layer made of a fluorescent organic solid such as anthracene, Alternatively, a structure having various combinations such as a laminate of such a light-emitting layer and an electron injection layer made of a perylene derivative, or a stack of these hole injection layer, light-emitting layer, and electron injection layer is known. It has been.

  In organic EL display devices, holes and electrons are injected into the organic light-emitting layer by applying a voltage to the transparent electrode and the metal electrode, and the energy generated by recombination of these holes and electrons excites the fluorescent material. Then, light is emitted on the principle that the excited fluorescent material emits light when returning to the ground state. The mechanism of recombination in the middle is the same as that of a general diode, and as can be predicted from this, the current and the emission intensity show strong nonlinearity with rectification with respect to the applied voltage.

  In an organic EL display device, in order to extract light emitted from the organic light emitting layer, at least one of the electrodes must be transparent, and a transparent electrode usually formed of a transparent conductor such as indium tin oxide (ITO) is used as an anode. It is used as. On the other hand, in order to facilitate electron injection and increase luminous efficiency, it is important to use a material having a small work function for the cathode, and usually metal electrodes such as Mg—Ag and Al—Li are used.

  In the organic EL display device having such a configuration, the organic light emitting layer is formed of a very thin film having a thickness of about 10 nm. For this reason, the organic light emitting layer transmits light almost completely like the transparent electrode. As a result, light that is incident from the surface of the transparent substrate at the time of non-light emission, passes through the transparent electrode and the organic light emitting layer, and is reflected by the metal electrode is again emitted to the surface side of the transparent substrate. The display surface of the organic EL display device looks like a mirror surface.

  In an organic EL display device comprising an organic electroluminescent light emitting device comprising a transparent electrode on the surface side of an organic light emitting layer that emits light upon application of a voltage and a metal electrode on the back side of the organic light emitting layer, the surface of the transparent electrode While providing a polarizing plate on the side, a retardation plate can be provided between the transparent electrode and the polarizing plate.

  Since the retardation plate and the polarizing plate have a function of polarizing light incident from the outside and reflected by the metal electrode, there is an effect that the mirror surface of the metal electrode is not visually recognized by the polarization action. In particular, the mirror surface of the metal electrode can be completely shielded by configuring the retardation plate with a quarter-wave plate and adjusting the angle formed by the polarization direction of the polarizing plate and the retardation plate to π / 4. .

  That is, only the linearly polarized light component of the external light incident on the organic EL display device is transmitted by the polarizing plate. This linearly polarized light becomes generally elliptically polarized light by the phase difference plate, but becomes circularly polarized light particularly when the phase difference plate is a quarter wavelength plate and the angle formed by the polarization direction of the polarizing plate and the phase difference plate is π / 4. .

  This circularly polarized light is transmitted through the transparent substrate, the transparent electrode, and the organic thin film, is reflected by the metal electrode, is again transmitted through the organic thin film, the transparent electrode, and the transparent substrate, and becomes linearly polarized light again on the retardation plate. And since this linearly polarized light is orthogonal to the polarization direction of a polarizing plate, it cannot permeate | transmit a polarizing plate. As a result, the mirror surface of the metal electrode can be completely shielded.

  In order to obtain this circularly polarized light, for example, by using the laminated optical film of the present invention in which a quarter-wave plate is laminated as an optical compensation layer, reflection of external light is suppressed, and organic EL with high visibility even outdoors. A display device can be obtained. Such an organic EL display device is also preferable in that it has excellent scratch resistance, like the liquid crystal display device.

  Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited to the examples shown below. The following examples and comparative examples were evaluated by the following methods.

(Water contact angle)
It measured by the droplet method using the contact angle meter [Kyowa Interface Science Co., Ltd. product name "CA-X"].

(Measurement of average particle size)
The average particle size of the colloid in the aqueous metal colloid solution was measured by a dynamic light scattering method (light correlation method) with a particle size distribution meter (manufactured by Nikkiso, product name “Nanotrack UAP150”).

(Thickness)
It measured with the digital micrometer (Anritsu KC-351C type | mold).

(Measurement of phase difference)
Using an automatic birefringence measuring device (manufactured by Oji Scientific Instruments Co., Ltd., automatic birefringence meter KOBRA-WPR), the front direction at a measurement wavelength of 590 nm and the retardation when the film is tilted by 40 ° about the slow axis, From these values, the refractive indexes nx, ny, and nz in the direction in which the in-plane refractive index is maximum, the direction perpendicular thereto, and the thickness direction of the film were calculated. From these values and thickness (d), in-plane retardation: Re = (nx−ny) × d and thickness direction retardation: Rth = (nx−nz) × d were obtained.
(Photoelastic coefficient)
Using a spectroscopic ellipsometer (manufactured by JASCO Corporation, product name “M-220”), the retardation value of the sample was measured under stress, and calculated from the slope of the function of the stress and retardation value. Specifically, the retardation value in the film plane at a wavelength of 590 nm when a stress of 5N to 15N was applied to a 2 cm × 10 cm test piece at 23 ° C. was measured.

(Pencil hardness)
After placing the laminated optical film on the glass plate with the second protective film side main surface facing down, the surface of the laminated optical film on the first protective film side is in accordance with the pencil hardness test described in JIS K-5600 (however, , Load 500 g), pencil hardness was measured.

(Adhesion of cured layer)
The adhesion of the cured layer to the first protective film was evaluated by performing a cross-cut peel test described in JIS K-5400. That is, the peeling test was performed 100 times, the number of peeling of the hard coat layer from the film substrate was counted, and the number of peeling / 100 was expressed.

(Appearance inspection: Knick defect)
Two polarizing plates are cut out so as to form a square of 1000 mm × 1000 mm, and ^two are laminated on a fluorescent lamp with a luminance of 8000 candela / m ² so that the transmission axes thereof are orthogonal to each other. Were visually counted.

[Example 1]
(Acrylic protective film)
90 parts by weight of polymethyl methacrylate resin (manufactured by Mitsubishi Rayon Co., Ltd., Acrypet VH) and 10 parts by weight of acrylonitrile-styrene copolymer (Asahi Kasei Co., Ltd., Stylac AS) which acts to eliminate the birefringence. It was melted and extruded from a die to form a film on a cast roll. Thereafter, the film was stretched longitudinally by a zone stretching method at a longitudinal stretching ratio of 1.8 times to obtain a polymethyl methacrylate film in which molecules were uniaxially oriented. Further, this film uniaxially oriented was made to have a biaxially oriented molecular methylpolymethacrylate having a thickness of 40 μm as a main component by increasing the transverse draw ratio by 2.2 times by a tenter stretching method. . The photoelastic coefficient of the obtained film was 5 × 10 ⁻¹² m ² / N.

(Cellulosic protective film)
A triacetyl cellulose (TAC) film (manufactured by Konica Minolta, trade name “KC4UYW”, thickness 40 μm, refractive index: 1.48), 6.0% by weight (1.5 N), hydroxylated at a temperature of 55 ° C. Saponification was performed by immersing in an aqueous sodium solution for 30 seconds and treating with alkali. The water contact angle of the obtained saponified triacetylcellulose film was 20 degrees on both sides, and the photoelastic coefficient was 1.5 × 10 ⁻¹¹ m ² / N.
(Preparation of cured layer forming material)
Resin raw material containing a resin component containing the following components (A), (B), (C) and a photopolymerization initiator in a mixed solvent of ethyl acetate and butyl acetate at a solid content concentration of 66% by weight (Dainippon) A product name GRANDIC PC1071) manufactured by Ink Co., Ltd. was prepared. To this resin raw material, 0.5% by weight of a leveling agent was added, and further butyl acetate: ethyl acetate (weight ratio) = 46: 54 (ethyl acetate ratio with respect to the total solvent 54 weight%), and the solid content concentration was 50 weight. %, The hard coat layer forming material was prepared by diluting with ethyl acetate. The leveling agent is a copolymer obtained by copolymerization at a molar ratio of dimethylsiloxane: hydroxypropylsiloxane: 6-isocyanatohexyl isocyanuric acid: aliphatic polyester = 6.3: 1.0: 2.2: 1.0. It is a thing.

(A) component): urethane acrylate (100 parts by weight) comprising pentaerythritol acrylate and hydrogenated xylene diisocyanate
Component (B): 49 parts by weight of dipentaerythritol hexaacrylate (hereinafter referred to as B1 component (monomer)), 41 parts by weight of pentaerythritol tetraacrylate (hereinafter referred to as B4 component (monomer)), and pentaerythritol triacrylate (hereinafter referred to as B5 component) (Monomer)) 24 parts by weight (C) component: a polymer having a repeating unit represented by the general formula (II), a mixture of copolymers (59 parts by weight),
Photopolymerization initiator: Ciba Specialty Chemicals, trade name “Irgacure 184” 3 parts by weight Mixing: butyl acetate / ethyl acetate = 89/11 (weight ratio)

(Formation of cured layer)
The cured layer forming material is applied to one side of the cellulose-based protective film (saponified triacetyl cellulose film) obtained above using a bar coater, and the coating film is dried by heating at 100 ° C. for 1 minute. I let you. Thereafter, ultraviolet rays with an integrated light quantity of 300 mJ / cm ² were irradiated with a metal halide lamp and cured to form a cured layer having a thickness of 20 μm.

(Creating a polarizer)
A polyvinyl alcohol film having an average degree of polymerization of 2700 and a thickness of 75 μm was stretched and conveyed while being dyed between rolls having different peripheral speeds. First, it was immersed in a 30 ° C. water bath for 1 minute to swell the polyvinyl alcohol film and stretched 1.2 times in the conveying direction, and then a 30 ° C. potassium iodide concentration of 0.03% by weight and an iodine concentration of 0.3 By immersing in a weight% aqueous solution for 1 minute, the film was stretched 3 times in the transport direction with reference to a film (original length) that was not stretched at all while dyeing. Next, the film was stretched 6 times based on the original length in the conveying direction while being immersed in an aqueous solution having a boric acid concentration of 4% by weight and a potassium iodide concentration of 5% by weight for 30 seconds. Next, the obtained stretched film was dried at 70 ° C. for 2 minutes to obtain a polarizer. The polarizer had a thickness of 30 μm and a moisture content of 14.3% by weight.

(Preparation of metal colloid-containing adhesive)
Polyvinyl alcohol resin having an acetoacetyl group (average polymerization degree 1200, saponification degree 98.5% mol%, acetoacetylation degree 5 mol%) 100 parts by weight, 50 parts by weight of methylol melamine at 30 ° C. Under the conditions, it was dissolved in pure water to prepare an aqueous solution having a solid content concentration of 3.7% by weight. An adhesive solution was prepared by adding 18 parts by weight of an aqueous solution containing alumina colloid having a positive charge (average particle size of 15 nm) at a solid content concentration of 10% by weight to 100 parts by weight of this aqueous solution. The viscosity of the adhesive solution was 9.6 mPa · s, the pH was in the range of 4 to 4.5, and the compounding amount of the alumina colloid was 74 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin.

(Creation of laminated optical film)
On the surface of the cellulose-based protective film (corresponding to the first protective film) on which the cured layer is formed, the above-described metal colloid-containing adhesive is applied to the adhesive layer having a thickness of 80 nm after drying. It applied so that it might become. Further, a metal colloid-containing adhesive was similarly applied to one side of the acrylic protective film (corresponding to the first protective film). These protective films coated with the adhesive were bonded to the respective main surfaces of the above-described polarizer using a roll machine and dried at 55 ° C. for 6 minutes to prepare a laminated optical film (polarizing plate).

[Example 2]
(First optical compensation layer)
A modified polycarbonate film having a thickness of 77 μm (trade name “Pure Ace WR-S”, manufactured by Teijin Kasei Co., Ltd.) that has already been stretched was used as the first optical compensation layer film. This film has a refractive index distribution of nx> ny = nz, shows a wavelength dispersion characteristic in which a phase difference value that is an optical path difference between extraordinary light and ordinary light increases as the wavelength increases, and the in-plane position at 590 nm The phase difference Re was 147 nm.

(Second optical compensation layer)
90 parts by weight of a nematic liquid crystalline compound represented by the following formula (10), 10 parts by weight of a chiral agent represented by the following formula (38), a photopolymerization initiator (Irgacure 907, manufactured by Ciba Specialty Chemicals) 5 Part by weight and 300 parts by weight of methyl ethyl ketone were uniformly mixed to prepare a liquid crystal coating liquid. This liquid crystal coating solution is applied onto a substrate (biaxially stretched PET film) by spin coating, heat treated at 80 ° C. for 3 minutes, and then irradiated with ultraviolet rays (20 mJ / cm ² , wavelength 365 nm) for polymerization treatment. A long second optical compensation layer (cholesteric alignment solidified layer) having a refractive index distribution of nx = ny> nz was formed. The thickness of this layer was 2 μm, the in-plane retardation Re was 0 nm, and the thickness direction retardation Rth was 110 nm.

(Preparation of polarizing plate with optical compensation layer)
The obtained first optical compensation layer was bonded (transferred) so that an isocyanate resin adhesive layer (thickness: 5 μm) coated on the main surface of the second optical compensation layer was opposed to the first optical compensation layer. The adhesive layer was cured by heating at 50 ° C. for about 10 hours. Next, the polarizing plate obtained in Example 1 was bonded to the opposite side of the first optical compensation layer from the adhesive layer using an acrylic pressure-sensitive adhesive (thickness 20 μm). At this time, lamination was performed such that the slow axis of the first optical compensation layer was 45 ° counterclockwise with respect to the absorption axis of the polarizer of the polarizing plate. Finally, the base material (biaxially stretched PET film) on which the second optical compensation layer was supported was peeled off to obtain a laminated optical film (optical compensation polarizing plate).

[Reference Example 1]
(Preparation of metal colloid-free adhesive)
An adhesive containing no metal colloid was prepared in the same manner as in Example 1 except that 18 parts by weight of pure water was added instead of 18 parts by weight of the aqueous alumina colloid solution.

(Creation of laminated optical film)
A laminated optical film (polarizing plate) was prepared in the same manner as in Example 1 except that the above metal colloid-free adhesive was used as the adhesive.

[Comparative Example 1]
As the second protective film, a laminated optical film (polarizing plate) was prepared in the same manner as in Example 1 except that the above-mentioned cellulose-based protective film (those not formed with a cured layer) was used instead of the acrylic protective film. Created.

[Comparative Example 2]
In Example 2, in place of the polarizing plate obtained in Example 1, the first optical compensation layer and the second optical compensation layer were obtained in the same manner as in Example 2 except that the polarizing plate obtained in Comparative Example 1 was used. A laminated optical film (optical compensation polarizing plate) having an optical compensation layer was obtained.

[Comparative Example 3]
A cured layer was formed on the cellulose-based protective film in the same manner as in Comparative Example 1, except that Nippon Paper Industries' urethane / acrylic hard coat agent was used as the cured layer forming material.
In Comparative Example 1, a laminated optical film was prepared in the same manner as in Comparative Example 1 except that the cellulose protective film (those not formed with a cured layer) was used as the second protective film instead of the acrylic protective film. (Polarizing plate) was prepared.

[Comparative Example 4]
In Example 2, in place of the polarizing plate obtained in Example 1, the first optical compensation layer and the second optical compensation layer were obtained in the same manner as in Example 2 except that the polarizing plate obtained in Comparative Example 3 was used. A laminated optical film (optical compensation polarizing plate) having an optical compensation layer was obtained.

[Comparative Example 5]
One primary surface of the acrylic protective film of Example 1 was subjected to silicon primer treatment, and a cured layer was formed on the treated surface in the same manner as in Example 1. The contact angle of water on the treated surface of the acrylic protective film subjected to the silicon primer treatment was 50 degrees.

  A laminated optical film (polarizing plate) was prepared in the same manner as in Example 1 except that the acrylic protective film having the cured layer was used instead of the cellulose protective film having the cured layer formed in Example 1. did.

  Table 1 shows the structures of the laminated optical films of Examples, Reference Examples and Comparative Examples, and the pencil hardness, the adhesion test of the cured layer, and the evaluation results of knick defects.

As is clear from Table 1, the laminated optical film of the present invention had a high surface hardness and excellent adhesion to the cured layer. Moreover, compared with the film of the reference example using the adhesive agent which does not contain a metal colloid, there was no light omission by a nick and visibility was also favorable.

(Durability test under humid heat environment)
All the optical films arranged above and below the liquid crystal cell of the VA mode liquid crystal display device (mobile phone manufactured by SHARP, model number: Q01iS) were removed, and the glass surface of the liquid crystal cell was washed. On both main surfaces of this liquid crystal cell, the laminated optical film obtained in Example 1 above is an acrylic pressure-sensitive adhesive (thickness 20 μm) so that the second protective film side main surface opposes the glass surface of the liquid crystal cell. Were bonded together. When laminating the laminated optical film, the arrangement angle was adjusted so as to maintain the arrangement angle of the polarizer in the liquid crystal display device before peeling the optical film. The liquid crystal panel provided with the laminated optical film of Example 1 on both the upper and lower surfaces of the liquid crystal cell thus obtained was re-incorporated into the liquid crystal display device, and was kept at a constant temperature and humidity of 60 ° C. and 90% relative humidity. It was put into an oven, taken out after 100 hours, and allowed to cool to room temperature. Thereafter, the panel was lit in a black display state in a dark room, and the presence or absence of deterioration of the display state was confirmed.

  The laminated optical films obtained in Example 2 and Comparative Examples 1 to 4 were also checked for the presence or absence of display state deterioration under wet heat conditions in the same manner as described above. The obtained result (photograph) is shown in FIG.

  As is clear from FIG. 4, the laminated optical film of the present invention has less unevenness even in a heated and humidified environment, whereas the laminated optical films of Comparative Examples 1 to 4 are when left in a heated and humidified environment. It can be seen that unevenness is likely to occur. In particular, when Example 2 having an optical compensation layer was compared with Comparative Examples 2 and 4, the difference in occurrence of heat unevenness was significant.

  As described above, according to the present invention, it is possible to obtain a laminated optical film that not only has a high surface hardness but also has a small change in optical properties even in a heated and humidified environment. In particular, in the laminated optical film of the present invention having an optical compensation layer, the effect of suppressing changes in optical properties is remarkable.

(Measurement of dimensional change)
The laminated optical film (polarizing plate) on which the cured layer obtained in Example 1 and Comparative Example 3 was formed was cut out so as to be a square of 100 mm × 100 mm, and a constant temperature and humidity oven at a temperature of 60 ° C. and a relative humidity of 90%. Then, the dimensional change in each of the machine direction (MD direction) and the width direction (TD) direction perpendicular thereto was measured every 500 hours until 500 seconds later. FIG. 5A shows the dimensional change in the MD direction, and FIG. 5B shows the dimensional change rate in the TD direction. In addition, the vertical axis | shaft of FIG. 5 represents the dimensional change rate. Both the laminated optical films of Example 1 and Comparative Example 3 are reduced in size by being exposed to a heated and humidified environment for a long time. However, the dimensional change amount of the laminated optical film of Example 1 is smaller. It was.

  Thus, the laminated optical film of the present invention has a cured layer formed on the first protective film using the cured layer forming material containing the component (A), the component (B), and the component (C). Therefore, the dimensional change is suppressed, and thereby the change in the optical characteristics of the polarizer, the second protective film, or the optical compensation layer is also suppressed. Therefore, it is estimated that the durability under high temperature and high humidity conditions is excellent.

It is a conceptual diagram which shows an example of the structure cross section of the laminated optical film of this invention. It is a conceptual diagram which shows an example of the structure cross section of the laminated optical film of this invention. It is a conceptual diagram which shows an example of the structure cross section of the laminated optical film of this invention. The generation | occurrence | production state of the thermal nonuniformity after the heating humidification test of the liquid crystal display device using the laminated | multilayer optical film of an Example and a comparative example is represented. It is a graph showing the dimensional change in the heating humidification test of the laminated optical film of Example 1 and Comparative Example 3.

Explanation of symbols

P Polarizer F1 First protective film F2 Second protective film H Cured layer L Antireflection layer R Optical compensation layer

Claims (6)

The first protective film (F1) having a contact angle with water on the surface of at least one film of 40 degrees or less, the polarizer (P), and the absolute value of the photoelastic coefficient are 1.0 × 10 ⁻¹¹ m ² / The second protective film (F2) containing a transparent resin that is N or less is laminated in this order,
A cured layer (using a cured layer forming material containing the following component (A), component (B) and component (C)) on the main surface of the first protective film (F1) where the polarizer is not laminated ( A laminated optical film having H).
(A) Component: At least one of urethane acrylate and urethane methacrylate (B) Component: At least one of polyol acrylate and polyol methacrylate (C) Component: Polymer or copolymer formed from at least one of the following (C1) and (C2) Or the mixed polymer (C1) including the polymer or the copolymer: an alkyl acrylate having an alkyl group having at least one group of a hydroxyl group and an acryloyl group (C2): having an alkyl group having at least one group of a hydroxyl group and an acryloyl group Alkyl methacrylate The polarizer (P) and the second protective film (F2) are laminated via an adhesive layer, and the adhesive layer has a polyvinyl alcohol resin, a crosslinking agent, and an average particle size of 1 to 100.
An adhesive for polarizing plate, which is a resin solution containing a metal compound colloid of nm, and the metal compound colloid is blended at a ratio of 200 parts by weight or less with respect to 100 parts by weight of the polyvinyl alcohol resin The laminated optical film according to claim 1, which is formed by:   The laminated optical film according to claim 1 or 2, wherein the second protective film (F2) contains an acrylic resin or a cyclic polyolefin resin.   The laminated optical film according to claim 1, wherein the first protective film (F1) contains a cellulose resin.   A laminated optical film further comprising at least one optical compensation layer (R) on the second protective film (F2) side of the laminated optical film according to claim 1.   An image display device comprising the laminated optical film according to claim 1.