JP5980465B2 - Polarizing plate and liquid crystal display device using the same - Google Patents

Description

  The present invention relates to a polarizing plate that achieves both suppression of occurrence of partial deformation failure and high visibility (clearness) under high temperature and high humidity conditions, and a liquid crystal display device using the polarizing plate.

  In general, two polarizing plates are bonded to a liquid crystal cell constituting a liquid crystal display panel of a liquid crystal display device (LCD). In this polarizing plate, a polyvinyl alcohol (hereinafter abbreviated as “PVA”) film in which iodine or a dichroic dye is adsorbed and dyed between two cellulose-based protective films is stretched and oriented in a certain direction. It has a three-layer structure with a polarizing element (polarizing film) in between. Moreover, in order to bond a polarizing plate and the board | substrate of a liquid crystal cell, the adhesive layer is provided in the cellulose protective film single side | surface.

  The protective film on the outermost surface of the polarizing plate used in the liquid crystal cell is particularly susceptible to physical damage, and when it is damaged, the display image quality is impaired. Therefore, a hard coat layer is formed on the substrate of the cellulose-based protective film. The provided hard coat film is used.

  In recent years, a hard coat film is required to be a clear type rather than an anti-glare treatment type that blurs the outline of an image reflected on the surface from the viewpoint of higher contrast and visibility (clearness).

  On the other hand, as the use of liquid crystal display devices is further expanded, the durability of liquid crystal display panels is demanded, and the necessity to store or use in harsh environments with high temperature and humidity for a long time has arisen. It was.

  If the polarizing plate provided with the adhesive layer of the liquid crystal display panel is assumed to be transported and stored under high temperature and high humidity for a long time in a stacked state, it will be partially on the outermost surface of the polarizing plate due to blocking etc. Deformation failures are likely to occur, which is a quality problem.

  For example, Patent Document 1 discloses a technique for polarizing plates that improves durability under high temperature and high humidity conditions. This technique improves the durability of a polarizing plate by treating a polarizing film, which is a hydrophilic polymer film, with an acidic solution and providing a protective film with a layer obtained by curing a polymerizable resin composition. . However, although the above technique can improve the discoloration of the polarizing plate to some extent, it cannot prevent the deformation failure that is the subject of the present invention.

  Patent Document 2 discloses at least one organic component having a polymerizable functional group, inorganic ultrafine particles, and a coating film component containing inorganic and / or organic fine particles having a primary particle size larger than the primary particle size of the inorganic ultrafine particles. A technique for preventing blocking of a hard coat film by a hard coat film formed from the above is disclosed. However, if fine particles are added in order to sufficiently prevent blocking, the haze is likely to increase, and there is still a problem in achieving both the prevention of deformation failure, which is the subject of the present invention, and visibility (clearness). It was.

JP 2008-70571 A JP 2001-13303 A

  The present invention has been made in view of the above-described problems and situations, and a solution to that problem is polarization that achieves both suppression of partial deformation failure and high visibility (clearness) under high-temperature and high-humidity conditions. It is to provide a plate and a liquid crystal display device using the same.

  As a result of intensive studies on the above problems, the present inventor has found that the hard coat layer of the hard coat film to be bonded to the polarizing plate has a thermoplastic polyester resin, a thermoplastic polyester urethane resin and an ethylenic resin. We have found that by including at least one resin selected from acrylic resins that do not have saturated double bonds, the protrusion shape of the hard coat layer can be controlled by a specific number, and the protrusion shape of the hard coat layer is specified. By controlling the haze value of the hard coat film, it is possible to disperse the stress applied to each polarizing plate when stored with the polarizing plates stacked, and the elastic modulus of the polarizing plate by storage under high temperature and high humidity conditions Prevention of partial deformation failure caused by the lowering, and the hard coat film according to the present invention as the outermost film of the liquid crystal display device That is not impaired even cleared by the user, using Te is understandable, found that it is possible to achieve both partial deformation suppressing generation and visibility of the fault (clear resistance), leading to the present invention.

  That is, the said subject which concerns on this invention is solved by the following means.

1. A protective film, a polarizing film, and a polarizing plate in which a hard coat film having a hard coat layer on a substrate film is laminated in this order, and the number of the hard coat layers in the range of 500 to 200,000 pieces / mm ² And at least one resin selected from the group consisting of a thermoplastic polyester resin, a thermoplastic polyester urethane resin, and an acrylic resin having no ethylenically unsaturated double bond. Further, the haze value of the hard coat film is in the range of 0.2 to 0.7%,
The hard coat layer includes at least one resin selected from the thermoplastic polyester resin, thermoplastic polyester urethane resin, and acrylic resin having no ethylenically unsaturated double bond, and a binder component . a resin composition containing an active ray curable resin, the said resin composition, and the active ray curable resin, wherein at least one of the content ratio by mass of the resin 60: 2 to 100: 10 range der is, at least a polarizing plate as a kind of resin and active ray curable resin of the binder component and said state der Rukoto phase separation.

  2. 2. The polarizing plate according to 1 above, wherein the arithmetic average roughness Ra (JIS B0601: 2001) of the hard coat layer is in the range of 3 to 20 nm.

  3. The base film of the hard coat film contains a thermoplastic acrylic resin and a cellulose ester resin, and the mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = 95: 3. The polarizing plate as described in 1 or 2 above, which falls within a range of 5 to 50:50.

  4). The protective film contains a thermoplastic acrylic resin and a cellulose ester resin, and the mass ratio of the thermoplastic acrylic resin to the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = 95: 5 to 50:50. The polarizing plate according to any one of 1 to 3, wherein the polarizing plate is in the range of 1 to 3.

  5). 5. A liquid crystal display device comprising the polarizing plate according to any one of 1 to 4 in at least one of liquid crystal cells.

  By the above means of the present invention, it is possible to provide a polarizing plate that achieves both suppression of occurrence of partial deformation failure under high temperature and high humidity conditions and visibility (clearness), and a liquid crystal display device using the polarizing plate. it can.

Cross-sectional observation with a transmission electron microscope of the protrusion shape of the hard coat layer Schematic diagram of a hard coat film having a hard coat layer and a polarizing plate Conceptual diagram showing the method of durability test of polarizing plate

The polarizing plate of the present invention is a polarizing plate in which a protective film, a polarizing film, and a hard coat film having a hard coat layer on a substrate film are laminated in this order, and the hard coat layer is 500 to 200000 pieces / Among the acrylic resin having a number of protrusions in the range of mm ² and the hard coat layer having no thermoplastic polyester resin, thermoplastic polyester urethane resin, or ethylenically unsaturated double bond It contains at least one selected resin, and the haze value of the hard coat film is in the range of 0.2 to 0.7%. This feature is a technical feature common to the inventions according to claims 1 to 4.

  As an embodiment of the present invention, the arithmetic average roughness Ra (JIS B0601: 2001) of the hard coat layer is preferably in the range of 3 to 20 nm from the viewpoint of manifesting the effects of the present invention. Further, the base film of the hard coat film contains a thermoplastic acrylic resin and a cellulose ester resin, and the mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = It is preferably within the range of 95: 5 to 50:50. Furthermore, the protective film contains a thermoplastic acrylic resin and a cellulose ester resin, and the mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = 95: 5-50. Is preferably in the range of 50.

  The polarizing plate of the present invention can be suitably used for a liquid crystal display device by being provided in at least one of the liquid crystal cells.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail.

<Number of protrusions, protrusion shape>
The hard coat layer according to the present invention is characterized by having a number of protrusions in the range of 500 to 200,000 pieces / mm ² , and the number of protrusions present is a value measured by the following method.

  The number of protrusions can also be measured from a hard coat layer arranged on the viewing side when used in a display device such as a liquid crystal display device.

  The number of protrusions was measured by measuring the hard coat layer with an optical interference surface roughness meter (RST / PLUS, manufactured by WYKO, magnification 50 times). Next, the number of protrusions in this measurement area (100 μm × 100 μm square) was read from the image. This series of measurements was performed 10 times, and the number of protrusions of the hard coat layer of the hard coat film was determined from the average value of 10 times.

  As the number of protrusions, protrusions having a height of 3 nm or more from the average line of the roughness curve were counted.

  The protrusion shape has a height of 1 nm to 5 μm, preferably 1 nm to 1 μm, preferably 10 nm to 0.5 μm. The width is 50 nm to 100 μm, preferably 50 nm to 50 μm.

  The width and height of the protrusion shape can be obtained from the following cross-sectional observation. FIG. 1 is an explanatory view of the protrusion. The cross-section of the hard coat film was cut in the film width direction at room temperature at an angle of 0 ° using a microtome (manufactured by Japan Microtome Laboratory). Next, this cross section was observed using a transmission electron microscope (TEM, magnification 2000 times). From the cross-sectional image, in accordance with the definition of JIS B 0601: 2001, as shown in the figure, the center line a is drawn on the image, and the lines b and c forming the mountain ridge and the center line a are two. The distance between the two intersections was defined as the protrusion size width t. Further, the distance from the summit to the center line a is obtained as the height h of the protrusion size.

  The arithmetic average roughness Ra specified in JIS B0601: 2001 of the hard coat layer according to the present invention is preferably 2 to 20 nm, and more preferably 3 to 20 nm. By setting it as the said range, it is excellent in visibility (clearness), and also exhibits an excellent effect in suppressing the occurrence of partial deformation failure after the durability test.

  The arithmetic average roughness of the hard coat layer can be measured and analyzed using a commercially available surface roughness measuring instrument. In the present invention, it can be determined using a small surface roughness measuring instrument (model number; SJ-401, manufactured by Mitutoyo Corporation). Moreover, it can also measure with the optical interference type surface roughness measuring device, for example, can measure using non-contact surface fine shape measuring device WYKO NT-2000 by WYKO.

<Resin>
The hard coat layer according to the present invention has protrusions as described above, and the hard coat layer has a thermoplastic polyester resin, a thermoplastic polyester urethane resin, and an acrylic resin having no ethylenically unsaturated double bond. It contains at least one kind of resin selected from the series resins.

  The above-mentioned resin is easy to be surface-oriented, and is easy to phase-separate when mixed with the binder component of the hard coat layer described later, so that a fine protrusion shape with excellent productivity and reproducibility can be obtained on the hard coat layer surface. Inferred.

  The number of protrusions can be controlled within the above-described range by selecting the above-described resin addition amount and the binder component of the hard coat layer described later.

  In addition, as a method of providing the projection shape, a method of adding fine particles, a method of forming a projection on the surface by pressing a mold, or a method of forming surface irregularities by mixing resins having different SP values (solubility parameters) (for example, , Methods described in JP 2007-182519 A and JP 2009-13384 A) may be used in combination.

  As mold rolls used to form protrusions, those with fine irregularities and coarse ones can be selected and applied as appropriate, and patterns, mats, lenticular lenses, and spherical irregularities are regularly or randomly arranged. it can.

  These resins may be used alone or in combination of two or more.

  First, the thermoplastic polyester resin will be described. Examples of polyester resins include ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, 1,5-pentanediol, 1,6-hexanediol, and neopentyl glycol. , Cyclohexane-1,4-dimethanol, hydrogenated bisphenol A, at least one selected from alcohol components such as ethylene oxide and propylene oxide adducts of bisphenol A, terephthalic acid, isophthalic acid, naphthalenedicarboxylic acid, cyclohexane-1 , 4-dicarboxylic acid, adipic acid, azelaic acid, maleic acid, fumaric acid, itaconic acid, polymerization obtained by condensation polymerization with at least one selected from carboxylic acid components such as acid anhydrides thereof And the like. Next, the thermoplastic polyester urethane resin will be described. Examples of polyester urethane resins include polymers obtained by reacting various polyisocyanate compounds with polyester polyols having hydroxyl groups at the terminals obtained by condensation polymerization of the alcohol component and carboxylic acid component. Can be mentioned. Examples of commercially available polyester resins and polyester urethane resins include Byron Series (trade name) manufactured by Toyobo Co., Ltd.

  The acrylic resin having no ethylenically unsaturated double bond will be described. As the acrylic resin, a polymer of at least one monomer selected from (meth) acrylic acid alkyl esters having 1 to 20 carbon atoms in the alkyl group, or the above (meth) acrylic acid alkyl esters and others And a copolymer with a copolymerizable monomer. Examples of the carboxyl group-containing acrylic resin include those synthesized by the method described in JP-A-8-193101. Specifically, it can be obtained as a copolymer by partial neutralization of monoethylenically unsaturated dicarboxylic acid and acrylic acid and / or methacrylic acid.

  Examples of the monoethylenically unsaturated dicarboxylic acid include maleic acid, itaconic acid, mesaconic acid, fumaric acid, methylenemalonic acid, citraconic acid, and maleic anhydride. Moreover, as a commercial item of acrylic resin, ARUFON-UP1000 series, UH2000 series, UC3000 series (brand name): Toagosei Co., Ltd. product etc. are mentioned.

  The three types of resins are collectively referred to as resins.

  The content ratio of the actinic radiation curable resin described later and the resin is preferably in the range of 100: 0.01 to 100: 10 on a mass basis and contained in the hard coat layer. By using the thermoplastic resin in this range, the protrusion shape of the hard coat layer is formed well, the clearness is excellent, and the good hardness (scratch resistance) is also obtained.

<Haze>
The haze value of the hard coat film according to the present invention is used in the range of 0.2 to 0.7%. Not only can the objective effect of the present invention be achieved by setting the haze value of the hard coat film to 0.2 to 0.7%, but it is sufficient when used outdoors such as large liquid crystal display devices and digital signage. It is also preferable in that high brightness and high contrast can be obtained. If the haze value of the hard coat film is less than 0.2%, it is difficult to design from the viewpoint of the handleability of the hard coat film.

  The haze value of the hard coat film comprises the hard coat layer coated on the base film when a base film having an appropriate haze value (0.1 to 0.5%) is used. It can control within the said range by adjusting the content ratio of the binder component of resin and a hard-coat layer. Further, since the surface roughness also affects the haze value as the surface haze, it is effective to control the shape and number of the protrusions.

<Hard coat film>
The hard coat film according to the present invention is composed of at least a base film and a hard coat layer, and the hard coat layer contains a binder component. As the binder component, an actinic radiation curable resin is preferable. Here, “active ray curable resin” refers to a resin whose main component is a resin that is cured through a crosslinking reaction upon irradiation with active rays such as ultraviolet rays or electron beams (also referred to as “active energy rays”).

(Actinic radiation curable resin)
As the actinic radiation curable resin, a component containing a monomer having an ethylenically unsaturated double bond is preferably used, and an actinic radiation curable resin layer is formed by curing by irradiation with actinic radiation such as ultraviolet rays or electron beams. The Typical examples of the actinic radiation curable resin include an ultraviolet curable resin and an electron beam curable resin, but the resin that is cured by ultraviolet irradiation is excellent in mechanical film strength (abrasion resistance, pencil hardness). preferable. As the ultraviolet curable resin, for example, an ultraviolet curable urethane acrylate resin, an ultraviolet curable polyester acrylate resin, an ultraviolet curable epoxy acrylate resin, an ultraviolet curable polyol acrylate resin, or an ultraviolet curable epoxy resin is preferable. Used. Of these, ultraviolet curable acrylate resins are preferred. As the ultraviolet curable acrylate resin, a polyfunctional acrylate is preferable. The polyfunctional acrylate is preferably selected from the group consisting of pentaerythritol polyfunctional acrylate, dipentaerythritol polyfunctional acrylate, pentaerythritol polyfunctional methacrylate, and dipentaerythritol polyfunctional methacrylate. Here, the polyfunctional acrylate is a compound having two or more acryloyloxy groups or methacryloyloxy groups in the molecule. Examples of the polyfunctional acrylate monomer include ethylene glycol diacrylate, diethylene glycol diacrylate, 1,6-hexanediol diacrylate, neopentyl glycol diacrylate, trimethylolpropane triacrylate, trimethylolethane triacrylate, and tetramethylolmethane triacrylate. , Tetramethylolmethane tetraacrylate, pentaglycerol triacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate, glycerol triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol Lithol hexaacrylate, tris (acryloyloxyethyl) isocyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, Tetramethylol methane trimethacrylate, tetramethylol methane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerol trimethacrylate, dipentaerythritol trimethacrylate, dipentaerythritol tetramethacrylate Acrylate, dipentaerythritol penta methacrylate, dipentaerythritol hexa methacrylate, isobornyl acrylate and the like preferably. These compounds are used alone or in combination of two or more. Moreover, oligomers, such as a dimer and a trimer of the said monomer, may be sufficient.

  The hard coat layer preferably contains a photopolymerization initiator to accelerate the curing of the actinic radiation curable resin. The amount of the photopolymerization initiator is preferably contained in a mass ratio of photopolymerization initiator: active ray curable resin = 20: 100 to 0.01: 100.

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

(solvent)
In the coating composition when the hard coat film according to the present invention is applied, a mixed solvent comprising a good solvent for the thermoplastic resin and a poor solvent for the thermoplastic resin is preferably used as a solvent. . Here, the good solvent and the poor solvent refer to solvents having solubility measured by the following method.

  When a solvent whose solubility is to be measured is added to a solid content of 3 g corresponding to 3 g of the thermoplastic resin so that the total amount is 20 g and stirred at a temperature of 25 ° C., it is uniform and transparent and has a viscosity change. Those that are compatible with each other are considered to be good solvents for the sample, while those that are found to be dusty, thickened, or separated are considered to be poor solvents for the sample.

  When the thermoplastic resin is, for example, a polyester resin or a polyester urethane resin, examples of the good solvent include toluene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetone, ethyl acetate, and tetrahydrofuran. On the other hand, examples of the poor solvent include xylene, ethyl cellosolve, propylene glycol monomethyl ether, isobutanol, isopropanol, ethanol, methanol, hexane, and purified water. When the thermoplastic resin is an acrylic resin, examples of the good solvent include toluene, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, acetone, ethyl acetate, tetrahydrofuran, xylene, and the like. On the other hand, examples of the poor solvent include ethyl cellosolve, propylene glycol monomethyl ether, isobutanol, isopropanol, ethanol, methanol, hexane, and purified water. The good solvent and the poor solvent other than purified water are good solvents for the commonly used actinic radiation curable resins.

  In the present invention, the good solvent and the poor solvent may be used alone or in combination of two or more with respect to the thermoplastic resin.

  The hard coat layer according to the present invention may contain fine particles of an inorganic compound or an organic compound.

(Fine particles)
As inorganic fine particles, silicon oxide, titanium oxide, aluminum oxide, tin oxide, indium oxide, ITO, zinc oxide, zirconium oxide, magnesium oxide, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated silicic acid Mention may be made of calcium, aluminum silicate, magnesium silicate and calcium phosphate. In particular, silicon oxide, titanium oxide, aluminum oxide, zirconium oxide, magnesium oxide and the like are preferably used.

  These inorganic fine particles are preferably coated with an organic component having a reactive functional group on a part of the surface because the scratch resistance is improved while maintaining the transparency of the hard coat film. As a method for coating an organic component having a reactive functional group on a part of the surface, for example, a compound containing an organic component such as a silane coupling agent reacts with a hydroxyl group present on the surface of the metal oxide fine particles, and the surface A mode in which an organic component is bonded to a part of the metal particle, a mode in which an organic component is attached to a hydroxyl group present on the surface of a metal oxide fine particle by an interaction such as a hydrogen bond, or one or more inorganic particles in a polymer particle The aspect containing microparticles | fine-particles etc. are mentioned.

  Organic particles include polymethacrylic acid methyl acrylate resin powder, acrylic styrene resin powder, polymethyl methacrylate resin powder, silicon resin powder, polystyrene resin powder, polycarbonate resin powder, benzoguanamine resin powder, and melamine resin. Powder, polyolefin resin powder, polyester resin powder, polyamide resin powder, polyimide resin powder, polyfluoroethylene resin powder, or the like can be added.

  Preferred fine particles include crosslinked polystyrene particles (for example, SX-130H, SX-200H, SX-350H manufactured by Soken Chemical), polymethyl methacrylate-based particles (for example, MX150, MX300 manufactured by Soken Chemical), and fluorine-containing acrylic resin fine particles. . Examples of the fluorine-containing acrylic resin fine particles include commercial products such as FS-701 manufactured by Nippon Paint. Examples of the acrylic particles include Nippon Paint: S-4000, and examples of the acrylic-styrene particles include Nippon Paint: S-1200, MG-251.

  The average particle size of these fine particle powders is not particularly limited, but is preferably 0.01 to 5 μm, and more preferably 0.01 to 1.0 μm. Moreover, you may contain 2 or more types of microparticles | fine-particles from which a particle size differs. The average particle diameter of the fine particles can be measured by, for example, a laser diffraction particle size distribution measuring device.

  The proportion of the ultraviolet curable resin composition and the fine particles is desirably blended so as to be 1 to 400 parts by mass, and more desirably 50 to 200 parts by mass with respect to 100 parts by mass of the resin composition.

  These hard coat layers are coated using a known method such as a gravure coater, dip coater, reverse coater, wire bar coater, die coater, ink jet method, and the like. And can be formed by UV curing.

  The coating amount is suitably 0.1 to 40 μm, preferably 0.5 to 30 μm, as the wet film thickness. The dry film thickness is from 0.1 to 30 μm, preferably from 1 to 20 μm, particularly preferably from 6 to 15 μm.

  As a light source for UV curing treatment, any light source that generates ultraviolet rays can be used without limitation. For example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp, or the like can be used.

Irradiation conditions vary depending on each lamp, but the irradiation amount of active rays is usually 5 to 500 mJ / cm ² , preferably 5 to 200 mJ / cm ² .

  Moreover, when irradiating actinic radiation, it is preferable to carry out while applying tension | tensile_strength in the conveyance direction of a film, More preferably, it is performing applying tension | tensile_strength also in the width direction. The tension to be applied is preferably 30 to 300 N / m. The method for applying tension is not particularly limited, and tension may be applied in the transport direction on the back roll, or tension may be applied in the width direction or biaxial direction by a tenter. Thereby, a film having further excellent flatness can be obtained.

  The hard coat layer may contain a conductive agent in order to impart antistatic properties, and preferred conductive agents include metal oxide particles or π-conjugated conductive polymers. An ionic liquid is also preferably used as the conductive compound.

  In addition, the hard coat layer has a nonionic surfactant such as a silicone surfactant, a fluorosurfactant or a polyoxyether, an anionic interface, from the viewpoint of coating properties and the uniform dispersibility of fine particles. An activator or the like can also be contained. These enhance the applicability. Moreover, it is preferable to add these components in 0.01-3 mass% with respect to the solid content component in a coating liquid.

  FIG. 2 shows a schematic diagram of a hard coat film having a hard coat layer according to the present invention and a polarizing plate. In FIG. 2, two layers such as the hard coat layers 2a and 2b are laminated, but one layer or a plurality of layers may be used. In order to easily control the hard coat property, haze, protrusion shape formed on the surface, and arithmetic surface roughness Ra of the hard coat layer, the hard coat layer is preferably divided into two or more layers. The film thickness of the uppermost layer when two or more layers are provided is preferably in the range of 0.05 to 2 μm from the viewpoint of adhesion to the lower layer. Two or more layers may be formed as a simultaneous multilayer. The simultaneous multi-layer is to form a hard coat layer by applying two or more hard coat layers on a base material without going through a drying step. In order to laminate the second hard coat layer on the first hard coat layer without a drying process, the layers are stacked one after another by an extrusion coater or simultaneously by a slot die having a plurality of slits. Can be done.

  The hard coat film in the present invention has a pencil hardness, which is an index of hardness, of H or higher, more preferably 2H or higher. If it is 2H or more, it is not only difficult to be scratched in the polarizing plate forming step of the liquid crystal display device, but is also used for outdoor applications, and is a surface protective film for large liquid crystal display devices and liquid crystal display devices for digital signage. When used as an excellent film strength. The pencil hardness is evaluated by pencil hardness evaluation specified by JIS K5400 using a test pencil specified by JIS S 6006 after the prepared hard coat film is conditioned at a temperature of 23 ° C. and a relative humidity of 55% for 2 hours or more. It is the value measured according to the method.

<Base film>
The base film is preferably easy to manufacture, easy to adhere to the hard coat layer, and optically isotropic. Moreover, a base film can also be used as a protective film.

  Any of these may be used, for example, cellulose ester films such as triacetyl cellulose film, cellulose acetate propionate film, cellulose diacetate film, cellulose acetate butyrate film, polyethylene terephthalate, polyethylene naphthalate Polyester film, polycarbonate film, polyarylate film, polysulfone (including polyethersulfone) film, polyethylene film, polypropylene film, cellophane, polyvinylidene chloride film, polyvinyl alcohol film, ethylene vinyl alcohol film, syndiotactic Tick polystyrene film, norbornene resin film, polymethylpentene film, Li ether ketone film, polyether ketone imide film, a polyamide film, a fluororesin film, a nylon film, cycloolefin polymer films, and polymethyl methacrylate film or an acrylic film or the like. Among these, cellulose ester films (for example, Konica Minoltak KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UE, KC4UE, and KC12UR (above, Konica Minolta Opto Co., Ltd., Polycarbonate Film) Olefin polymer films and polyester films are preferred, and in the present invention, the cellulose ester film is particularly advantageous in terms of production, cost, isotropy, adhesiveness (saponification suitability), and the object effects of the present invention. preferable. The refractive index of the base film is preferably 1.30 to 1.70, and more preferably 1.40 to 1.65. The refractive index is measured by the method of JIS K7142 using an Atpe refractometer 2T.

<Cellulose ester film>
Next, a cellulose ester film preferable as a substrate film will be described. The cellulose ester resin (hereinafter also referred to as cellulose ester) is preferably a lower fatty acid ester of cellulose. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. For example, cellulose acetate, cellulose propionate, cellulose butyrate, etc. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate as described in US Pat. No. 2,319,052 and the like can be used.

  Among the above descriptions, the lower fatty acid esters of cellulose particularly preferably used are cellulose triacetate and cellulose acetate propionate. These cellulose esters can be used alone or in combination.

  In the case of cellulose triacetate, those having an average degree of acetylation (bound acetic acid amount) of 54.0 to 62.5% are preferably used, and more preferably an average degree of acetylation of 58.0 to 62.5%. Cellulose triacetate.

  When the average degree of acetylation is small, the dimensional change is large, and the polarization degree of the polarizing plate is lowered. When the average degree of acetylation is large, the solubility in a solvent is lowered and productivity is lowered.

  Preferred cellulose esters other than cellulose triacetate have an acyl group having 2 to 4 carbon atoms as a substituent, and when the substitution degree of acetyl group is X and the substitution degree of propionyl group or butyryl group is Y, the following formula ( It is a cellulose ester including a cellulose ester that simultaneously satisfies I) and (II).

Formula (I) 2.6 ≦ X + Y ≦ 3.0
Formula (II) 0 ≦ X ≦ 2.5
Of these, cellulose acetate propionate is preferably used, and it is particularly preferable that 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9. The portion that is not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods. The measuring method of the substitution degree of an acyl group can be measured according to ASTM-D817-96.

  The molecular weight of the cellulose ester is preferably a number average molecular weight (Mn) of 60,000 to 300,000, more preferably 70,000 to 200,000, particularly preferably 100,000 to 200,000. The cellulose ester used in the present invention preferably has a weight average molecular weight (Mw) / number average molecular weight (Mn) ratio of 4.0 or less, more preferably 1.4 to 2.3.

  Since the average molecular weight and molecular weight distribution of the cellulose ester can be measured using high performance liquid chromatography, the number average molecular weight (Mn) and the weight average molecular weight (Mw) can be calculated using this, and the ratio can be calculated.

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (GL Science Co., Ltd.)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0 ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corporation)
A calibration curve with 13 samples from Mw = 100000 to 500 was used. The 13 samples are preferably used at approximately equal intervals.

<Cellulose ester resin / thermoplastic acrylic resin-containing film>
The base film contains a thermoplastic acrylic resin and a cellulose ester resin from the viewpoint of exerting the object effect of the present invention even in a more severe durability test, and the content mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is It is preferable to use a thermoplastic acrylic resin: cellulose ester resin = 95: 5 to 50:50 base film (hereinafter also referred to as a cellulose ester resin / acrylic resin film). More preferably, it is 90: 10-60: 40.

  The thermoplastic acrylic resin includes a methacrylic resin. Although it does not restrict | limit especially as a thermoplastic acrylic resin, What consists of 50-99 mass% of methyl methacrylate units and 1-50 mass% of other monomer units copolymerizable with this is preferable. Other monomers that can be copolymerized include alkyl methacrylates having 2 to 18 carbon atoms, alkyl acrylates having 1 to 18 carbon atoms, acrylic acid, methacrylic acid, and the like. Unsaturated group-containing divalent carboxylic acids such as saturated acid, maleic acid, fumaric acid and itaconic acid, aromatic vinyl compounds such as styrene and α-methylstyrene, α, β-unsaturated nitriles such as acrylonitrile and methacrylonitrile, Maleic anhydride, maleimide, N-substituted maleimide, glutaric anhydride and the like can be mentioned, and these can be used alone or in combination of two or more monomers.

  Among these, methyl acrylate, ethyl acrylate, n-propyl acrylate, n-butyl acrylate, s-butyl acrylate, 2-ethylhexyl acrylate, and the like are preferable from the viewpoint of thermal decomposition resistance and fluidity of the copolymer. n-Butyl acrylate is particularly preferably used.

  Moreover, it is preferable that a weight average molecular weight (Mw) is 80000-500000, More preferably, it exists in the range of 110000-500000.

  The weight average molecular weight of the thermoplastic acrylic resin can be measured by the gel permeation chromatography described above, including the measurement conditions. There is no restriction | limiting in particular as a manufacturing method of an acrylic resin, You may use any well-known methods, such as suspension polymerization, emulsion polymerization, block polymerization, or solution polymerization. Here, as a polymerization initiator, a normal peroxide type and an azo type can be used, and a redox type can also be used. Regarding the polymerization temperature, suspension or emulsion polymerization may be performed at 30 to 100 ° C, and bulk or solution polymerization may be performed at 80 to 160 ° C. In order to control the reduced viscosity of the obtained copolymer, polymerization can be carried out using alkyl mercaptan or the like as a chain transfer agent. Commercial products can also be used. For example, Delpet 60N, 80N (Asahi Kasei Chemicals Co., Ltd.), Dianal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Denki Kagaku Kogyo Co., Ltd.) and the like can be mentioned. . Two or more thermoplastic acrylic resins can be used in combination. The thermoplastic acrylic resin includes a graft copolymer obtained by grafting a (meth) acrylic resin to a copolymer of (meth) acrylic rubber and an aromatic vinyl compound described in JP-A-2009-84574. It may be used. In the graft copolymer, a copolymer of (meth) acrylic rubber and an aromatic vinyl compound forms a core, and the (meth) acrylic resin forms a shell around the copolymer. -It is preferably a shell-type graft copolymer.

  Each of the thermoplastic acrylic resin and the cellulose ester resin is preferably an amorphous resin, and either one may be a crystalline polymer or a partially crystalline polymer. The resin and the cellulose ester resin are preferably compatible with each other to become an amorphous resin.

  After the weight average molecular weight (Mw) of the thermoplastic acrylic resin in the base film, the weight average molecular weight (Mw) of the cellulose ester resin and the degree of substitution are separated using the difference in solubility in the solvent of both resins, , Obtained by measuring each. When fractionating the resin, it is possible to extract and separate the soluble resin by adding a compatible resin in a solvent that is soluble only in either one. At this time, heating operation or reflux is performed. May be. A combination of these solvents may be combined in two or more steps to separate the resin. The dissolved resin and the resin remaining as an insoluble matter are filtered off, and the solution containing the extract can be separated by an operation of evaporating the solvent and drying. These fractionated resins can be identified by general structural analysis of polymers. Moreover, also when a base film contains resin other than a thermoplastic acrylic resin and a cellulose-ester resin, it can fractionate by the same method. By comparing the amounts of various resins obtained by separation, the content ratio of the thermoplastic acrylic resin and the cellulose ester resin may be in the range of thermoplastic acrylic resin: cellulose ester resin = 95: 5 to 50:50. Can be confirmed.

  If the weight average molecular weights (Mw) of the compatible resins are different, the high molecular weight substances are eluted earlier by gel permeation chromatography (GPC), and the lower molecular weight substances are eluted after a longer time. Therefore, it can be easily fractionated and the molecular weight can be measured.

  The total mass of the thermoplastic acrylic resin and the cellulose ester resin in the base film is preferably 55% by mass or more of the optical film, more preferably 60% by mass or more, and particularly preferably 70% by mass or more. . The base film may contain a resin other than acrylic resin and cellulose ester resin and additives.

<Acrylic particles>
The base film preferably contains acrylic particles from the viewpoint of improving brittleness and obtaining excellent pencil hardness. An acrylic particle represents the acrylic component which exists in the state of particle | grains (it is also called an incompatible state) in the base film containing the said thermoplastic acrylic resin and cellulose-ester resin in a compatible state.

  The particle diameter of the acrylic particles is not particularly limited, but is preferably 10 nm or more and 1000 nm or less, and more preferably 20 nm or more and 500 nm or less. Examples of commercially available products include, for example, “Metablene” manufactured by Mitsubishi Rayon Co., “Kane Ace” manufactured by Kaneka Chemical Co., Ltd., “Paraloid” manufactured by Kureha Chemical Co., Ltd., “Acryloid” manufactured by Rohm and Haas Co. “Staffyroid” and “Parapet SA” manufactured by Kuraray Co., Ltd. can be mentioned, and these can be used alone or in combination of two or more.

  The acrylic fine particles are acrylic fine particles: thermoplastic acrylic resin and cellulose ester resin total mass = 0.5: 100 to 30 in terms of the mass ratio to the total mass of the thermoplastic acrylic resin and the cellulose ester resin constituting the base film. Is preferably in the range of 100: more preferably acrylic fine particles: the total mass of the thermoplastic acrylic resin and the cellulose ester resin = 1.0: 100 to 15: 100.

<Other additives>
In order to improve the fluidity and flexibility of the composition, a plasticizer can be used in combination with the base film. Examples of the plasticizer include phthalate ester, fatty acid ester, trimellitic ester, phosphate ester, polyester, and epoxy. Of these, polyester and phthalate plasticizers are preferably used. Polyester plasticizers are superior in non-migration and extraction resistance compared to phthalate ester plasticizers such as dioctyl phthalate, but are slightly inferior in plasticizing effect and compatibility.

  The polyester plasticizer is a reaction product of a monovalent or tetravalent carboxylic acid and a monovalent or hexavalent alcohol, and is mainly obtained by reacting a divalent carboxylic acid with a glycol. . Representative divalent carboxylic acids include glutaric acid, itaconic acid, adipic acid, phthalic acid, azelaic acid, sebacic acid and the like.

  The polyester-based plasticizer may be any of ester, oligoester, and polyester types, and the molecular weight is preferably in the range of 100 to 10000, but preferably in the range of 600 to 3000, which has a large plasticizing effect.

  The viscosity of the plasticizer has a correlation with the molecular structure and molecular weight. In the case of an adipic acid plasticizer, the viscosity is preferably in the range of 200 to 5000 mPa · s (25 ° C.) in view of compatibility and plasticization efficiency. Furthermore, some polyester plasticizers may be used in combination.

  The plasticizer is preferably added in an amount of 0.5 to 30 parts by mass with respect to 100 parts by mass of the base film. If the added amount of the plasticizer exceeds 30 parts by mass, the surface becomes sticky, which is not preferable for practical use.

  The base film preferably also contains an ultraviolet absorber, and examples of the ultraviolet absorber used include benzotriazole-based, 2-hydroxybenzophenone-based or salicylic acid phenyl ester-based ones. For example, 2- (5-methyl-2-hydroxyphenyl) benzotriazole, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2H-benzotriazole, 2- (3 Triazoles such as 5-di-t-butyl-2-hydroxyphenyl) benzotriazole, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-octoxybenzophenone, 2,2'-dihydroxy-4-methoxybenzophenone And benzophenones. Here, among ultraviolet absorbers, ultraviolet absorbers having a molecular weight of 400 or more are less likely to volatilize at a high boiling point and are difficult to disperse even during high-temperature molding, so that the weather resistance is effectively improved with a relatively small amount of addition. be able to.

  Examples of the ultraviolet absorber having a molecular weight of 400 or more include 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole, 2,2-methylenebis [4- (1, 1,3,3-tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol], bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis ( Hindered amines such as 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-n-butylmalonic acid Bis (1,2,2,6,6-pentamethyl-4-piperidyl), 1- [2- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] ethyl L] -4- [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy] -2,2,6,6-tetramethylpiperidine and the like, hindered phenol and hindered amine Examples include hybrid systems having both structures, and these can be used alone or in combination of two or more.

  Among these, 2- [2-hydroxy-3,5-bis (α, α-dimethylbenzyl) phenyl] -2-benzotriazole and 2,2-methylenebis [4- (1,1,3,3- Tetrabutyl) -6- (2H-benzotriazol-2-yl) phenol] is particularly preferred.

  Furthermore, various antioxidants can also be added to the base film in order to improve the thermal decomposability and thermal colorability during molding. It is also possible to add an antistatic agent to give the base film antistatic performance.

  A flame retardant acrylic resin composition containing a phosphorus flame retardant may be used for the base film.

  Phosphorus flame retardants used here include red phosphorus, triaryl phosphate ester, diaryl phosphate ester, monoaryl phosphate ester, aryl phosphonate compound, aryl phosphine oxide compound, condensed aryl phosphate ester, halogenated alkyl phosphorus. Examples thereof include one or a mixture of two or more selected from acid esters, halogen-containing condensed phosphate esters, halogen-containing condensed phosphonate esters, halogen-containing phosphite esters, and the like. Specific examples include triphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, tris (β-chloroethyl) phosphate, tris (dichloropropyl). Examples thereof include phosphate and tris (tribromoneopentyl) phosphate.

  In addition to the increase in the size of liquid crystal display devices and the increasing brightness of backlight light sources, the use of digital signage and other outdoor applications demands higher brightness. It is required to withstand use in a high-temperature environment, and it is preferable that the substrate film has sufficient heat resistance when the tension softening point is 105 ° C to 145 ° C, particularly 110 ° C. It is preferable to control to ˜130 ° C. The substrate film preferably has a glass transition temperature (Tg) of 110 ° C. or higher. More preferably, it is 120 ° C. or higher. Especially preferably, it is 150 degreeC or more. In addition, when a base film is used as a protective film for a polarizing plate of a liquid crystal display device, unevenness or a change in retardation value occurs due to a dimensional change due to moisture absorption, causing problems such as a decrease in contrast and uneven color. . In particular, the above problem becomes significant when the polarizing plate protective film is used in a liquid crystal display device used outdoors. For this reason, the dimensional change rate (%) is preferably less than 0.5%, and more preferably less than 0.3%.

  Moreover, it is preferable that a base film has a defect with a diameter of 5 μm or more in a film plane of 1/10 cm square or less from the viewpoint of prevention of film breakage and prevention of bright spots. More preferably, it is 0.5 piece / 10 cm square or less, more preferably 0.1 piece / 10 cm square or less.

  Here, the diameter of the defect indicates the diameter when the defect is circular, and when the defect is not circular, the range of the defect is determined by observing with a microscope by the following method, and the maximum diameter (diameter of circumscribed circle) is determined.

  The range of the defect is the size of the shadow when the defect is observed with the transmitted light of the differential interference microscope when the defect is a bubble or a foreign object. When the defect is a change in the surface shape, such as transfer of a roll flaw or an abrasion, the size is confirmed by observing the defect with the reflected light of a differential interference microscope.

  In addition, when observing with reflected light, if the size of the defect is unclear, aluminum or platinum is deposited on the surface for observation.

  In order to obtain a film having excellent quality expressed by such a defect frequency with high productivity, it is necessary to filter the polymer solution with high precision immediately before casting, to increase the cleanliness around the casting machine, It is effective to set drying conditions after rolling stepwise and to dry efficiently while suppressing foaming.

  Here, the defect is a void in the film (foaming defect) generated due to the rapid evaporation of the solvent in the drying process of the solution casting, a foreign matter in the film forming stock solution, or a foreign matter mixed in the film forming. This refers to the foreign matter (foreign matter defect) in the film.

  In addition, the base film preferably has a breaking elongation of at least one direction of 10% or more, more preferably 20% or more, in the measurement based on JIS-K7127-1999.

  The upper limit of the elongation at break is not particularly limited, but is practically about 250%. In order to increase the elongation at break, it is effective to suppress defects in the film caused by foreign matter and foaming.

  The thickness of the base film is preferably 20 μm or more. More preferably, it is 30 μm or more.

  The upper limit of the thickness is not particularly limited, but in the case of forming a film by a solution casting method, the upper limit is about 250 μm from the viewpoint of applicability, foaming, solvent drying, and the like. In addition, the thickness of a film can be suitably selected according to a use.

  The base film preferably has a total light transmittance of 90% or more, more preferably 93% or more. Moreover, as a realistic upper limit, it is about 99%. In order to achieve excellent transparency expressed by such total light transmittance, it is necessary not to introduce additives and copolymerization components that absorb visible light, or to remove foreign substances in the polymer by high-precision filtration. It is effective to reduce the diffusion and absorption of light inside the film.

  Also, reduce the surface roughness of the film surface by reducing the surface roughness of the film contact part (cooling roll, calender roll, drum, belt, coating substrate in solution casting, transport roll, etc.) during film formation. It is also effective to reduce the diffusion and reflection of light on the film surface by reducing the refractive index of the acrylic resin.

<Formation of base film>
Although the example of the film forming method of a base film is demonstrated, this invention is not limited to this. As a method for forming the base film, a production method such as an inflation method, a T-die method, a calendar method, a cutting method, a casting method, an emulsion method, or a hot press method can be used.

  From the viewpoint of suppressing the residual solvent using a cellulose ester resin or an acrylic resin for dissolution, a method using a melt casting film forming method is preferable. Methods formed by melt casting can be classified into melt extrusion molding methods, press molding methods, inflation methods, injection molding methods, blow molding methods, stretch molding methods, and the like. Among these, the melt extrusion method is preferable, in which a film having excellent mechanical strength and surface accuracy can be obtained. From the viewpoints of suppressing coloring, suppressing defects of foreign matters, and suppressing optical defects such as die lines, solution casting by casting is preferred.

  Further, a method of extruding and forming a film forming material on a drum or an endless belt after the film forming material is heated to express its fluidity is also included as a melt casting film forming method.

(Organic solvent)
The organic solvent useful for forming the dope when the base film is produced by the solution casting method can be used without limitation as long as it dissolves acrylic resin, cellulose ester resin, and other additives simultaneously. .

  For example, as the chlorinated organic solvent, methylene chloride, as the non-chlorinated organic solvent, methyl acetate, ethyl acetate, amyl acetate, acetone, tetrahydrofuran, 1,3-dioxolane, 1,4-dioxane, cyclohexanone, ethyl formate, 2,2,2-trifluoroethanol, 2,2,3,3-hexafluoro-1-propanol, 1,3-difluoro-2-propanol, 1,1,1,3,3,3-hexafluoro- Examples include 2-methyl-2-propanol, 1,1,1,3,3,3-hexafluoro-2-propanol, 2,2,3,3,3-pentafluoro-1-propanol, and nitroethane. Methylene chloride, methyl acetate, ethyl acetate and acetone can be preferably used.

  In addition to the organic solvent, the dope preferably contains 1 to 40% by mass of a linear or branched aliphatic alcohol having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the web gels and peeling from the metal support becomes easy, and when the proportion of alcohol is small, the acrylic resin and cellulose ester resin dissolve in a non-chlorine organic solvent system. There is also a role to promote.

  In particular, in a solvent containing methylene chloride and a linear or branched aliphatic alcohol having 1 to 4 carbon atoms, at least 15 to 45% by mass in total of at least three kinds of acrylic resin, cellulose ester resin, and acrylic particles. A dissolved dope composition is preferred.

  Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Ethanol is preferred because of the stability of these dopes, the relatively low boiling point, and good drying properties.

(Solution casting method)
Cellulose ester film, and cellulose ester resin / acrylic resin film are produced by a solution casting method, and a dope is prepared by dissolving cellulose ester or cellulose ester resin / acrylic resin and an additive in a solvent. A step of casting on a metal support in the form of a drum or a drum, a step of drying the cast dope as a web, a step of peeling from the metal support, a step of stretching or maintaining the width, a step of further drying, and a finished film It is performed by a winding process.

  The concentration of cellulose ester in the dope, and the concentration of cellulose ester resin / acrylic resin is preferably higher because the drying load after casting on the metal support can be reduced. The load increases, and the filtration accuracy deteriorates. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

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

  The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is set to −50 ° C. to a temperature at which the solvent boils and does not foam. A higher temperature is preferred because the web can be dried faster, but if it is too high, the web may foam or the flatness may deteriorate.

  The preferable support temperature is appropriately determined at 0 to 100 ° C, and more preferably 5 to 30 ° C. Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

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

  When using warm air, considering the temperature drop of the web due to the latent heat of vaporization of the solvent, while using warm air above the boiling point of the solvent, there may be cases where wind at a temperature higher than the intended temperature is used while preventing foam .

  In particular, it is preferable to perform drying efficiently by changing the temperature of the support and the temperature of the drying air during the period from casting to peeling.

  In order for the cellulose ester film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Especially preferably, it is 20-30 mass% or 70-120 mass%.

  The amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = {(MN) / N} × 100
Note that M is the mass of a sample collected during or after the production of the web or film, and N is the mass after heating M at 115 ° C. for 1 hour.

  Further, in the drying step of the cellulose ester film or the cellulose ester resin / acrylic resin film, it is preferable that the web is peeled off from the metal support and further dried to make the residual solvent amount 1% by mass or less, more preferably 0. 0.1 mass% or less, particularly preferably 0 to 0.01 mass% or less.

  In the film drying process, generally, a roll drying method (a method in which a large number of rolls arranged above and below are alternately dried by passing through a web) or a method of drying while transporting the web by a tenter method is adopted.

(Melting method)
The cellulose ester film and the cellulose ester resin / acrylic resin film are also preferably formed by a melt film forming method. In the melt film-forming method, a composition containing a cellulose ester and an additive such as a cellulose ester resin / acrylic resin and a plasticizer is melted by heating to a temperature showing fluidity, and then a melt containing a fluid cellulose ester. It means to cast.

  More specifically, the heat melting molding method can be classified into a melt extrusion molding method, a press molding method, an inflation method, an injection molding method, a blow molding method, a stretch molding method, and the like.

  Among these, in order to obtain a cellulose ester film excellent in mechanical strength and surface accuracy, and a cellulose ester resin / acrylic resin film, the melt extrusion method is excellent.

  It is preferable that a plurality of raw materials used for melt extrusion are usually kneaded in advance and pelletized.

  Pelletization may be performed by a known method. For example, dry cellulose ester, plasticizer, and other additives are fed to an extruder with a feeder and kneaded using a single-screw or twin-screw extruder, and formed into a strand from a die. It can be done by extrusion, water cooling or air cooling and cutting. The additives may be mixed before being supplied to the extruder, or may be supplied by individual feeders.

  A small amount of additives such as particles and antioxidants are preferably mixed in advance in order to mix uniformly.

  The extruder is preferably processed at as low a temperature as possible so as to be able to be pelletized so that the shear force is suppressed and the resin does not deteriorate (decrease in molecular weight, coloring, gel formation, etc.). For example, in the case of a twin screw extruder, it is preferable to rotate in the same direction using a deep groove type screw. From the uniformity of kneading, the meshing type is preferable.

  A film is formed using the pellets obtained as described above. Of course, the raw material powder can be directly fed to the extruder by a feeder without being pelletized to form a film as it is.

  Using a single or twin screw extruder, the pellets are melted at a temperature of about 200 to 300 ° C., filtered through a leaf disk filter, etc. to remove foreign matter, and then formed into a film from a T die. And the film is nipped with a cooling roll and an elastic touch roll and solidified on the cooling roll. The extrusion flow rate is preferably performed stably by introducing a gear pump or the like. Further, a stainless fiber sintered filter is preferably used as a filter used for removing foreign substances.

  The film temperature on the touch roll side when the film is nipped between the cooling roll and the elastic touch roll is preferably Tg or more and Tg + 110 ° C. or less of the film. A well-known roll can be used for the roll which has the elastic body surface used for such a purpose.

  As an elastic touch roll, the touch roll currently disclosed by the patent 3194904 specification, the patent 3422798 specification, Unexamined-Japanese-Patent No. 2002-36332, Unexamined-Japanese-Patent No. 2002-36333 etc. can be used preferably. These can also use what is marketed.

  When peeling the film from the cooling roll, it is preferable to control the tension to prevent deformation of the film. Moreover, it is preferable that the film obtained as described above is stretched by the stretching operation after passing through the step of contacting the cooling roll.

  As a method of stretching, a known roll stretching machine or tenter can be preferably used. The stretching temperature is usually preferably performed in the temperature range of Tg to Tg + 60 ° C. of the resin constituting the film.

  Prior to winding, the ends may be slit and cut to the width of the product, and knurling (embossing) may be applied to both ends to prevent sticking or scratching during winding. The knurling method can process a metal ring having an uneven pattern on its side surface by heating or pressing. In addition, since the film has deform | transformed and cannot use as a product normally, the holding | grip part of the clip of both ends of a film is cut out and reused.

<Functional layer>
The hard coat film according to the present invention may be provided with functional layers such as an antistatic layer, a backcoat layer, an antireflection layer, a slippery layer, an adhesive layer, an antiglare layer, and a barrier layer.

<Back coat layer>
The hard coat film may be provided with a back coat layer on the surface of the base film opposite to the side on which the hard coat layer is provided in order to prevent curling and sticking.

  As particles added to the back coat layer, examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, tin oxide, and oxidation. Mention may be made of indium, zinc oxide, ITO, hydrated calcium silicate, aluminum silicate, magnesium silicate and calcium phosphate. The particles contained in the backcoat layer are preferably 0.1 to 50% by mass with respect to the binder. When the back coat layer is provided, the increase in haze is preferably 1.5% or less, more preferably 0.5% or less, and particularly preferably 0.1% or less. As the binder, a cellulose ester resin such as diacetylcellulose is preferable.

<Antireflection layer>
The hard coat film can be used as an antireflection film having an external light antireflection function by coating an antireflection layer on the hard coat layer. The antireflection layer is preferably laminated in consideration of the refractive index, the film thickness, the number of layers, the layer order, and the like so that the reflectance is reduced by optical interference. The antireflection layer is preferably composed of a low refractive index layer having a refractive index lower than that of the support, or a combination of a high refractive index layer having a refractive index higher than that of the support and a low refractive index layer. Particularly preferably, it is an antireflection layer composed of three or more refractive index layers. Three layers having different refractive indexes from the support side are divided into medium refractive index layers (high refractive index layers having a higher refractive index than the support). Are preferably laminated in the order of a layer having a lower refractive index) / a high refractive index layer / a low refractive index layer. Alternatively, an antireflection layer having a four or more layer structure in which two or more high refractive index layers and two or more low refractive index layers are alternately laminated is also preferably used.

  As the layer structure of the antireflection film, the following structure is conceivable, but is not limited thereto.

Base film / hard coat layer / low refractive index layer Base film / hard coat layer / medium refractive index layer / low refractive index layer Base film / hard coat layer / medium refractive index layer / high refractive index layer / low refractive index Layer Base film / hard coat layer / high refractive index layer (conductive layer) / low refractive index layer Base film / hard coat layer / antiglare layer / low refractive index layer Low refraction essential for antireflection film The refractive index layer preferably contains silica-based fine particles, and the refractive index thereof is lower than the refractive index of the substrate film as the support, and is in the range of 1.30 to 1.45 at 23 ° C. and a wavelength of 550 nm. Preferably there is.

  The film thickness of the low refractive index layer is preferably 5 nm to 0.5 μm, more preferably 10 nm to 0.3 μm, and most preferably 30 nm to 0.2 μm. The composition for forming a low refractive index layer preferably contains at least one kind of particles having an outer shell layer and porous or hollow inside as silica-based fine particles. In particular, the particles having the outer shell layer and having a porous or hollow interior are preferably hollow silica-based fine particles.

  The composition for forming a low refractive index layer may contain an organosilicon compound represented by the following general formula (OSi-1) or a hydrolyzate thereof, or a polycondensate thereof.

General formula (OSi-1): Si (OR) ₄
In the organic silicon compound represented by the general formula, R represents an alkyl group having 1 to 4 carbon atoms. Specifically, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and the like are preferably used. In addition, a silane coupling agent, a curing agent, a surfactant and the like may be added as necessary.

<Polarizing plate>
The polarizing plate using the hard coat film according to the present invention will be described. The polarizing plate can be produced by a general method. The back surface side of the hard coat film according to the present invention is subjected to alkali saponification treatment, and a completely saponified polyvinyl alcohol aqueous solution is used on at least one surface of a polarizing film prepared by immersing and stretching the treated hard coat film in an iodine solution. It is preferable to stick them together.

  The hard coat film may be used on the other surface, or another polarizing plate protective film may be used. The polarizing plate protective film used on the other surface of the hard coat film according to the present invention contains an acrylic resin and a cellulose ester resin, similarly to the base film of the hard coat film. It is preferable to use a protective film in which the content ratio of the cellulose ester resin is acrylic resin: cellulose ester resin = 95: 5 to 50:50. Details of the configuration are as described above. Specifically, an example is a non-oriented film having a retardation Ro of 590 nm of 0 to 5 nm and an Rt of -20 to +20 nm described in JP-A No. 2003-12859.

  In addition, an optical compensation film (retardation film) having a retardation of in-plane retardation Ro of 590 nm, 20 to 70 nm, and Rt of 70 to 400 nm may be used as a polarizing plate capable of widening the viewing angle. it can. These can be produced, for example, by the method of JP-A-2002-71957. Alternatively, it is preferable to use an optical compensation film having an optical anisotropic layer formed by aligning a liquid crystal compound such as a discotic liquid crystal. For example, the optically anisotropic layer can be formed by the method described in JP-A-2003-98348.

  Moreover, as a commercially available polarizing plate protective film preferably used, KC8UX2MW, KC4UX, KC5UX, KC4UY, KC8UY, KC12UR, KC4UEW, KC8UCR-3, KC8UCR-4, KC8UCR-5, KC4FR-1, KC4FR-2, KC4FR-2, KC8FR-2 KC4UE (Konica Minolta Opto Co., Ltd.) etc. are mentioned.

  The polarizing film, which is the main component of the polarizing plate, is an element that transmits only light having a polarization plane in a certain direction. A typical polarizing film known at present is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol film. There are ones in which iodine is dyed on a system film and ones in which a dichroic dye is dyed, but it is not limited to this.

  As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxially stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound. A polarizing film having a thickness of 5 to 30 μm, preferably 8 to 15 μm, is preferably used.

  On the surface of the polarizing film, one side of the hard coat film according to the present invention is bonded to form a polarizing plate. It is preferably bonded with an aqueous adhesive mainly composed of completely saponified polyvinyl alcohol or the like.

<Adhesive layer>
The pressure-sensitive adhesive layer used on one side of the protective film to be bonded to the substrate of the liquid crystal cell is preferably optically transparent and exhibits moderate viscoelasticity and adhesive properties.

  Specific examples of the adhesive layer include adhesives or adhesives such as acrylic copolymers, epoxy resins, polyurethane, silicone polymers, polyethers, butyral resins, polyamide resins, polyvinyl alcohol resins, and synthetic rubbers. A film such as a drying method, a chemical curing method, a thermal curing method, a thermal melting method, a photocuring method, or the like can be formed and cured using a polymer such as the above. Among them, the acrylic copolymer can be preferably used because it is most easy to control the physical properties of the adhesive and is excellent in transparency, weather resistance, durability and the like.

<Liquid crystal display device>
By incorporating the polarizing plate of the present invention produced using the hard coat film according to the present invention into a display device, various image display devices with excellent visibility can be produced.

  The hard coat film according to the present invention is incorporated in a polarizing plate, and is a reflective type, transmissive type, transflective liquid crystal display device or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS. It is preferably used in liquid crystal display devices of various drive systems such as a type and an OCB type.

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

Example 1
<Preparation of base film 1 (cellulose ester film 1)>
(Preparation of dope solution)
The following materials were sequentially put into a sealed container, the temperature in the container was raised from 20 ° C. to 80 ° C., and the mixture was stirred for 3 hours while maintaining the temperature at 80 ° C. to completely dissolve the cellulose ester. . The silicon oxide fine particles were added dispersed in a solution of a solvent to be added in advance and a small amount of cellulose ester. This dope was filtered using a filter paper (Azumi filter paper No. 244, manufactured by Azumi Filter Paper Co., Ltd.) to obtain a dope solution A.

(Preparation of dope solution A)
Cellulose triacetate (acetyl group substitution degree 2.9) 100 parts by mass Trimethylolpropane tribenzoate 5 parts by mass Ethylphthalylethyl glycolate 5 parts by mass Fine particles of silicon oxide 0.1 parts by mass (Aerosil R972V, manufactured by Nippon Aerosil Co., Ltd.)
Tinuvin 109 (manufactured by Ciba Japan) 1 part by weight Tinuvin 171 (manufactured by Ciba Japan) 1 part by weight Methylene chloride 400 parts by weight Ethanol 40 parts by weight Butanol 5 parts by weight The above materials are mixed to prepare a dope solution A The obtained dope liquid A was cast through a casting die kept at a temperature of 35 ° C. onto a support at a temperature of 35 ° C. made of a stainless steel endless belt to form a web.

  Next, the web was dried on the support, and the web was peeled from the support with a peeling roll when the residual solvent amount of the web reached 80% by mass.

  Next, the web is transported while being dried with a drying air of 90 ° C. in a transport and drying process using a plurality of rolls arranged on the top and bottom, subsequently gripping both end portions of the web with a tenter, and then before stretching in the width direction at 130 ° C. The film was stretched so as to be 1 time. After stretching with a tenter, the web was dried with a drying air of 130 ° C. in a transport drying process using a plurality of rolls arranged vertically. After heat treatment for 15 minutes in an atmosphere with an atmosphere substitution rate of 15 (times / hour) in the drying step, the film was subjected to a knurling process with a width of 10 mm and a height of 10 μm at both ends of the film, cooled to room temperature, and wound on a core. A base film 1 having a thickness of 0.5 m, a thickness of 40 μm, and a length of 4000 m was produced.

<Preparation of hard coat film 1>
On the cellulose ester film 1 produced above, the following hard coat layer coating composition 1-1 is filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a hard coat layer coating solution, which is applied using a micro gravure coater. and, after drying at 80 ° C., using an ultraviolet lamp, irradiance 80 mW / cm ² irradiation unit to cure the coating layer the amount of irradiation as 80 mJ / cm ^2, forming a hard coat layer 1 dry film thickness 9μm did. Continuously, the hard coat layer coating composition 1-2 is applied onto the hard coat layer 1 by an extrusion coater, dried at 80 ° C., and nitrogen so that the oxygen concentration becomes 1.0 vol% or less. While purging, the irradiance of the irradiated part is 150 mW / cm ² using an ultraviolet lamp, the irradiation amount is 250 mJ / cm ² , the coating layer is cured, and the hard coat layer 2 having a dry film thickness of 0.6 μm is formed and wound. A roll-shaped hard coat film 1 was produced.

(Hard Coat Layer Coating Composition 1-1)
The following materials were stirred and mixed to obtain hard coat layer coating composition 1.

Pentaerythritol triacrylate 55 parts by mass Pentaerythritol tetraacrylate 55 parts by mass Irgacure 184 (manufactured by Ciba Japan, photopolymerization initiator) 5.0 parts by mass Polyether-modified silicone (KF354L, manufactured by Shin-Etsu Chemical Co., Ltd.) 2.0 parts by mass Propylene glycol monomethyl ether 10 parts by weight Methyl acetate 60 parts by weight Methyl ethyl ketone 70 parts by weight (hard coat layer coating composition 1-2)
The following materials were stirred and mixed to obtain a hard coat layer coating composition 1-2.

Thermoplastic resin, polyester urethane resin (manufactured by Toyobo Co., Ltd., trade name “Byron UR1350”, solid content concentration 33% (toluene / methyl ethyl ketone solvent = 65/35))
6.0 parts by mass (2.0 parts by mass for polyester urethane resin)
Pentaerythritol triacrylate 30 parts by mass Pentaerythritol tetraacrylate 30 parts by mass Irgacure 184 (manufactured by Ciba Japan, photopolymerization initiator) 3.0 parts by mass Irgacure 907 (manufactured by Ciba Japan, photopolymerization initiator) 1.0 Part by mass Polyether-modified polydimethylsiloxane (BYK-UV3510, manufactured by Big Chemie Japan) 2.0 parts by mass Propylene glycol monomethyl ether 150 parts by mass Methyl ethyl ketone 150 parts by mass <Preparation of hard coat films 2-12>
In the production of the hard coat film 1, the hard urethane film was coated in the same manner except that the polyester urethane resin (thermoplastic resin) of the hard coat layer coating composition 1-2 was changed to the resins and addition amounts (parts by mass) shown in Table 1. Coat films 2 to 12 were produced. In addition, in the addition of the polyester urethane resin (Byron UR1350, solid content concentration 33%), the amount of propylene glycol monomethyl ether was adjusted so that the solvent became a certain amount according to the amount added.

<Preparation of hard coat film 13>
In the production of the hard coat film 1, a hard coat layer 2 is not provided, and an ultraviolet lamp is used while purging with nitrogen so that the atmosphere of nitrogen oxide concentration is 1.0% by volume or less in the ultraviolet irradiation for producing the hard coat film. A hard coat film 13 was produced in the same manner except that the illuminance of the irradiated part was 150 mW / cm ² and the irradiation amount was 250 mJ / cm ² to cure the coating layer.

<Preparation of hard coat film 14>
In the production of the hard coat film 1, the hard coat layer 2 is not provided, the coating composition of the hard coat layer 1 is changed to the hard coat layer coating composition 14-1, and in the ultraviolet irradiation for producing the hard coat film, oxygen The same except that the coating layer was cured using an ultraviolet lamp while setting the irradiance to 150 mW / cm ² and the irradiation amount to 250 mJ / cm ² while purging with nitrogen so that the concentration was 1.0% by volume or less. Thus, a hard coat film 14 was produced.

(Hard Coat Layer Coating Composition 14-1)
The following materials were stirred and mixed to obtain a hard coat layer coating composition 14-1.

Thermoplastic resin, polyester resin (product name “Byron 220” manufactured by Toyobo Co., Ltd.)
8.0 parts by mass Pentaerythritol triacrylate 55 parts by mass Pentaerythritol tetraacrylate 55 parts by mass Irgacure 184 (Ciba Japan, photopolymerization initiator) 5.0 parts by mass Irgacure 907 (Ciba Japan, photopolymerization start) Agent) 1.0 part by mass Polyether-modified silicone (KF354L, manufactured by Shin-Etsu Chemical Co., Ltd.) 2.0 parts by mass Propylene glycol monomethyl ether 10 parts by mass Methyl acetate 60 parts by mass Methyl ethyl ketone 70 parts by mass <Preparation of hard coat film 15>
In the production of the hard coat film 14, the hard coat film 15 was formed in the same manner except that the addition amount of the thermoplastic resin (polyester resin, manufactured by Toyobo Co., Ltd., trade name “Byron 220”) was changed to 16 parts by mass. Produced.

<Preparation of hard coat film 16>
In the production of the hard coat film 1, the hard coat layer 2 was not provided, the hard coat layer coating composition 1-1 was applied, dried, and then a mold roll produced with reference to the example of JP-A-2008-276198. After embossing (here, the mold roll used was one in which the molds were regularly arranged), using an ultraviolet lamp while purging with nitrogen so that the atmosphere had an oxygen concentration of 1.0% by volume or less, A hard coat film 16 was produced in the same manner except that the coating layer was cured by setting the illuminance of the irradiated portion to 150 mW / cm ² and the irradiation amount to 250 mJ / cm ² to form the hard coat layer 1 having a dry film thickness of 9 μm.

<Preparation of hard coat film 17>
In the production of the hard coat film 17, the hard coat film 17 was produced in the same manner except that the shape of the mold roll was changed.

<Preparation of Polarizing Plate 101>
(Alkaline saponification treatment)
A polarizing plate 101 was prepared using one each of the hard coat film 1 and the base film 1 as a protective film for the polarizing plate.

(A) Production of Polarizing Film What was impregnated with 10 parts by mass of glycerin and 170 parts by mass of water in 100 parts by mass of polyvinyl alcohol (hereinafter abbreviated as PVA) having a saponification degree of 99.95 mol% and a polymerization degree of 2400. After melt-kneading and defoaming, it was melt-extruded from a T-die onto a metal roll to form a film. Then, it dried and heat-processed and obtained the PVA film.

  The obtained PVA film had an average thickness of 25 μm, a moisture content of 4.4%, and a film width of 3 m. Next, the obtained PVA film was continuously treated in the order of pre-swelling, dyeing, uniaxial stretching by a wet method, fixing treatment, drying, and heat treatment to produce a polarizing film. That is, the PVA film was preliminarily swollen in water at a temperature of 30 ° C. for 30 seconds, and immersed in an aqueous solution having an iodine concentration of 0.4 g / liter and a potassium iodide concentration of 40 g / liter at a temperature of 35 ° C. for 3 minutes. Subsequently, the film was uniaxially stretched 6 times in a 50% aqueous solution with a boric acid concentration of 4% under the condition that the tension applied to the film was 700 N / m, and the potassium iodide concentration was 40 g / liter and the boric acid concentration was 40 g / liter. Then, it was immersed in an aqueous solution having a zinc chloride concentration of 10 g / liter and a temperature of 30 ° C. for 5 minutes for fixing. Thereafter, the PVA film was taken out, dried with hot air at a temperature of 40 ° C., and further heat-treated at a temperature of 100 ° C. for 5 minutes. The obtained polarizing film had an average thickness of 13 μm, a polarizing performance of a transmittance of 43.0%, a polarization degree of 99.5%, and a dichroic ratio of 40.1.

(B) Production of Polarizing Plate A polarizing plate 101 was produced by bonding the polarizing film, the substrate film 1 and the hard coat film 1 according to the following steps 1 to 4.
Process 1: The above-mentioned polarizing film was immersed for 1 to 2 seconds in the storage tank of the polyvinyl alcohol adhesive agent solution of 2 mass% of solid content.
Process 2: The alkali saponification process was implemented on the hard-coat film 1 which affixed the peelable protective film (product made from PET) to the base film 1 and the hard-coat layer on the following conditions. Next, the excess adhesive adhered to the polarizing film immersed in the polyvinyl alcohol adhesive solution in Step 1 is lightly removed, and the base film 1 and the hard coat film 1 are sandwiched between the polarizing films as shown in FIG. Laminated.

(Alkaline saponification treatment)
Saponification step 2.5M-KOH 50 ° C. 120 seconds Water washing step Water 30 ° C. 60 seconds Neutralization step 10 parts by mass HCl 30 ° C. 45 seconds Water washing step Water 30 ° C. 60 seconds After saponification treatment, water washing, neutralization, water washing in this order And then dried at 100 ° C.
Step 3: The laminate was bonded at a speed of about 2 m / min at a pressure of ^{20 to} 30 N / cm ² with two rotating rollers. At this time, it was carried out with care to prevent bubbles from entering.
Step 4: The sample prepared in Step 3 was dried in a dryer at a temperature of 100 ° C. for 5 minutes to prepare a polarizing plate.
Step 5: A commercially available acrylic adhesive is applied to the base film 1 of the polarizing plate prepared in Step 4 so that the thickness after drying is 25 μm, and dried in an oven at 110 ° C. for 5 minutes to form an adhesive layer. Then, a peelable protective film was attached to the adhesive layer. This polarized light was cut (punched) into a size of 576 × 324 mm, and the polarizing plate 101 was produced.

<Production of Polarizing Plates 102 to 117>
Polarizers 102 to 117 were produced in the same manner except that the hard coat film 1 was changed to the hard coat films 2 to 17 in the production of the polarizer 101.

<Production of Liquid Crystal Display Device 401>
Remove the polarizing plate of NEC notebook PC LaVie G type liquid crystal panel, and make the above-prepared polarizing plate 101 (see FIG. 2 for the configuration) as the polarizing plate on the viewing side so that the hard coat layer is on the viewing side, Layer 5 and liquid crystal cell glass were bonded together. Further, on the backlight side, an acrylic adhesive having a thickness of 25 μm is used for the polarizing plate 201 that is laminated and bonded so as to sandwich the polarizing film with the base film 1 that has been subjected to alkali saponification treatment in the same manner as described above. A liquid crystal panel 301 was prepared by pasting the liquid crystal cell glass. Next, the liquid crystal panel 301 was set on a liquid crystal television, and a liquid crystal display device 401 was manufactured.

<Production of Liquid Crystal Display Devices 402 to 417>
Liquid crystal display devices 402 to 417 were similarly manufactured except that the polarizing plate 101 was changed to the polarizing plates 102 to 117 in manufacturing the liquid crystal display device 401.

<Evaluation>
The following evaluation was performed about the produced said hard coat films 1-17, the polarizing plates 101-117, and the image display apparatuses 401-417.

(Hard coat film)
a. Surface Roughness (Ra) Measurement The hard coat layers of the hard coat films 1 to 19 prepared above were measured 10 times using an optical interference type surface roughness meter (RST / PLUS, manufactured by WYKO), and the measurement results From the average, the surface roughness (Ra) of each hard coat film was determined. The obtained results are shown in Table 1.

b. Measurement of the number of protrusions When measuring the surface roughness (Ra), the number of protrusions was counted (number per measurement area of 0.01 mm ² ). Next, the number of projections of the hard coat layer of each hard coat film was determined by averaging the counted 10 results. As the number of protrusions, protrusions having a height of 3 nm or more from the average line of the roughness curve were counted. The obtained results are shown in Table 1.

c. Haze measurement The base film and each of the prepared hard coat films were measured using a haze meter (NDH2000; manufactured by Nippon Denshoku Industries Co., Ltd.) according to JIS-K7136. The haze value of the base film was 0.28%. Table 1 shows the haze values of the obtained hard coat films.

(Polarizer)
a. Durability test After peeling off the peelable protective film of the hard coat layer of the polarizing plates 101 to 117, 50 polarizing plates were stacked on each other as shown in FIG. The film was bonded to the top and stored for 240 hours at 80 ° C. and 90%.

b. Observation of deformation failure The polarizing plate subjected to the above durability test was observed from the hard coat layer side, and the state of deformation failure was observed according to the following criteria.

A: Deformation failure is not observed at all. O: Deformation failure is observed in a small part, but there is no problem in actuality. Δ: Deformation failure is partially observed. There is a problem in terms of actual damage ×: It can be seen that partial deformation failure is clearly seen even from a distance.

(Liquid crystal display device)
a. Visibility (clearness) evaluation The liquid crystal display devices 401 to 417 produced above were placed on a desk 80 cm high from the floor, and a daylight direct fluorescent lamp (FLR40S · D / M-X (Panasonic Corporation) 40W × 2 were used as one set, and 10 sets were arranged at 1.5 m intervals. In this case, when the evaluator is in front of the display surface of the liquid crystal display panel, the fluorescent lamp is arranged so that the fluorescent lamp comes to the ceiling portion from the evaluator's overhead to the rear. Next, the visibility of the liquid crystal display devices 401 to 417 was evaluated according to the following criteria. The obtained results are shown in Table 1.

○: Fluorescent light is clearly visible △: Fluorescent light is slightly whitish ×: Fluorescent light is blurred and appears whitish

Specific product names of the thermoplastic resins listed in Table 1 are as follows.
Polyester resin: Toyobo Co., Ltd., trade name “Byron 220”
Hydroxyl group-containing acrylic polymer (trade name “UH-2000” manufactured by Toagosei Co., Ltd.)
Carboxyl group-containing acrylic polymer: manufactured by Toagosei Co., Ltd., trade name “UC-3000”
As can be seen from the results in Table 1, the hard coat layer of the hard coat film is selected from thermoplastic polyester resins, thermoplastic polyester urethane resins, and acrylic resins having no ethylenically unsaturated double bonds. The polarizing plate of the present invention contains at least one kind of resin, the number of protrusions of the hard coat layer is 500 to 200000 / mm, and the haze value of the hard coat film is 0.2 to 0.7%. It exhibits excellent performance in both prevention of deformation failure when stored under high temperature and high humidity, and visibility (clearness) when used in a liquid crystal display device.

  Among the present inventions, the polarizing plate of the present invention in which the arithmetic average roughness Ra of the hard coat layer is 3 to 20 nm exhibits a particularly excellent deformation failure prevention effect. In addition, about the hard coat film and polarizing plate concerning this invention, after humidity-conditioning at 23 degreeC55% RH for 12 hours, using the pencil for a test prescribed | regulated by JIS-S6006, according to the pencil hardness evaluation method prescribed | regulated by JIS-K5400. The pencil hardness was tested using a 500 g weight. The pencil hardness of the hard coat film and the polarizing plate according to the present invention was 2H or more.

Example 2
In the production of the hard coat film 1, hard coat films 18 to 22 were produced in the same manner except that the substrate film 1 was changed to the following substrate films 2 to 6. Polarizers 118 to 122 and liquid crystal display devices 418 to 422 were produced using these produced hard coat films 18 to 22.

<Preparation of hard coat film 18>
(Preparation of base film 2)
(Adjustment of dope solution B)
Thermoplastic acrylic resin (Dianar BR85 (manufactured by Mitsubishi Rayon Co., Ltd.) Mw280000) 70 parts by weight Cellulose ester (cellulose acetate propionate acyl group total substitution degree: 2.75, acetyl group substitution degree 0.19, propionyl group substitution) Degree 2.56, Mw = 200000) 30 parts by mass Methylene chloride 300 parts by mass Ethanol 40 parts by mass The above composition was sufficiently dissolved while heating to prepare a dope solution.

(Film formation)
The produced dope solution B was uniformly cast on a stainless steel band support at a temperature of 22 ° C. and a width of 2 m using a belt casting apparatus. With the stainless steel band support, the solvent was evaporated until the amount of residual solvent reached 100%, and then peeled off from the stainless steel band support. The peeled thermoplastic acrylic resin / cellulose ester resin web was evaporated at 35 ° C., slit to 1.6 m width, and then stretched 1.1 times in the width direction with a tenter, followed by a drying temperature of 130 ° C. And dried. At this time, the residual solvent amount when starting stretching with a tenter was 10%. After stretching with a tenter, relaxation was performed at 130 ° C. for 5 minutes, and then drying was completed while transporting a drying zone at 120 ° C. and 140 ° C. with many rolls, slitting to a width of 1.5 m, and a width of 10 mm at both ends of the film Then, a knurling process having a height of 10 μm was performed and wound around a core to obtain a base film 2. The film thickness was 40 μm and the winding length was 4000 m.

(Preparation of base film 3-6)
In preparation of the base film 2, the types and content ratios of the acrylic resin and the cellulose ester resin were changed as shown in Table 2 to prepare base films 3 to 6.

<Preparation of polarizing plates 118 to 122>
Polarizers 118 to 122 were produced in the same manner except that the hard coat film 1 was changed to the hard coat films 18 to 22 in the production of the polarizer 101.

<Production of Liquid Crystal Display Devices 418 to 422>
Liquid crystal display devices 418 to 422 were similarly manufactured except that the polarizing plate 101 was changed to the polarizing plates 118 to 122 in the preparation of the liquid crystal display device 401.

<Evaluation>
In the durability test of the polarizing plate of Example 1, the polarizing plate 101 and the liquid crystal display device 401 produced in Example 1 and the hard coat films 18 to 18 produced in the same manner except that the storage time was changed to 480 hours. 22, polarizing plates 116 to 122 and liquid crystal display devices 418 to 422 were evaluated. The obtained results are shown in Table 2.

  As can be seen from the results in Table 2, in a more severe test, the base film contains a thermoplastic acrylic resin and a cellulose ester resin, and the contained mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is determined as follows: By using a film in the range of cellulose ester resin = 95: 5 to 50:50, the effect of preventing deformation failure is particularly excellent, and the visibility (clearness) when used in a liquid crystal display device is also good. .

Example 3
In preparation of the polarizing plate 101 of Example 1, the polarizing plates 123-127 were produced except having changed the protective film into the base film 2-6. Using these prepared polarizing plates, liquid crystal display devices 423 to 427 were manufactured.

<Evaluation>
In the same manner as in Example 2, the polarizing plate 101 and the liquid crystal display device 401 produced in Example 1 and the produced polarizing plates 123 to 127 and the liquid crystal display devices 423 to 427 were evaluated. The obtained results are shown in Table 3.

  As can be seen from the results in Table 3, in a more severe test, the protective film contains a thermoplastic acrylic resin and a cellulose ester resin, and the contained mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is determined as follows: thermoplastic acrylic resin: cellulose By using a film in the range of ester resin = 95: 5 to 50:50, the effect of preventing deformation failure is particularly excellent, and the visibility (clearness) when used in a liquid crystal display device is also good.

DESCRIPTION OF SYMBOLS 1 Base film 2a, 2b Hard coat layer 3 Polarizing film 4 Protective film 5 Adhesive layer 6 Hard coat film 7 Polarizing plate 8 Glass plate

Claims (5)

A protective film, a polarizing film, and a polarizing plate in which a hard coat film having a hard coat layer on a substrate film is laminated in this order, and the number of the hard coat layers in the range of 500 to 200,000 pieces / mm ² And at least one resin selected from the group consisting of a thermoplastic polyester resin, a thermoplastic polyester urethane resin, and an acrylic resin having no ethylenically unsaturated double bond. Further, the haze value of the hard coat film is in the range of 0.2 to 0.7%,
The hard coat layer includes at least one resin selected from the thermoplastic polyester resin, thermoplastic polyester urethane resin, and acrylic resin having no ethylenically unsaturated double bond, and a binder component . a resin composition containing an active ray curable resin, the said resin composition, and the active ray curable resin, wherein at least one of the content ratio by mass of the resin 60: 2 to 100: 10 range der is, at least a polarizing plate as a kind of resin and active ray curable resin of the binder component and said state der Rukoto phase separation.   2. The polarizing plate according to claim 1, wherein an arithmetic average roughness Ra (JIS B0601: 2001) of the hard coat layer is in a range of 3 to 20 nm.   The base film of the hard coat film contains a thermoplastic acrylic resin and a cellulose ester resin, and the mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = 95: It is in the range of 5-50: 50, The polarizing plate of Claim 1 or Claim 2 characterized by the above-mentioned.   The protective film contains a thermoplastic acrylic resin and a cellulose ester resin, and the mass ratio of the thermoplastic acrylic resin to the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = 95: 5 to 50:50. The polarizing plate according to any one of claims 1 to 3, wherein the polarizing plate is within the range.   A liquid crystal display device comprising the polarizing plate according to any one of claims 1 to 4 in at least one of liquid crystal cells.

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