JPWO2012026192A1 - Hard coat film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

Provided is a hard coat film that is improved in interlayer adhesion between a protective film and a hard coat layer after a weather resistance test. Moreover, the polarizing plate provided with the same and a liquid crystal display device are provided. The hard coat film of the present invention is a hard coat film having a hard coat layer on a base film, wherein the arithmetic average roughness Ra of the hard coat layer is in the range of 2 to 20 nm, and the arithmetic average roughness The ratio (Ra / RSm) between the height Ra and the average length RSm of the contour curve elements is in the range of 5 × 10 −5 to 3 × 10 −4.

Description

  The present invention relates to a hard coat film, a polarizing plate provided with the hard coat film, and a liquid crystal display device.

  Two polarizing plates are bonded to a liquid crystal cell constituting a liquid crystal display panel of a liquid crystal display device (LCD). This polarizing plate comprises two polarizing elements (polarizing films) in which a polyvinyl alcohol (hereinafter, abbreviated as “PVA”) film adsorbed and dyed with iodine or a dichroic dye is oriented in a certain direction. A three-layer structure sandwiched between two cellulose ester-based protective films.

  In general, the protective film on the outermost surface of the polarizing plate used in the liquid crystal cell is particularly susceptible to physical damage, and if it is damaged, the display image quality is impaired. Therefore, a hard film provided with a hard coat layer on the protective film. A coat film is used.

  On the other hand, because the cellulose ester-based protective film is susceptible to changes in dimensions due to the difference in use environment (influence of humidity) on the characteristics of the cellulose ester resin, additives are being studied to improve moisture permeability (for example, , See Patent Document 1).

  Although the moisture permeation resistance of the cellulose ester-based protective film is improved by the addition of these additives, there is a problem that interlayer adhesion between the cellulose ester-based protective film and the hard coat layer is difficult to take. In particular, there was a problem that interlaminar adhesion between the cellulose ester-based protective film and the hard coat layer was difficult to take after a weather resistance test assuming use in outdoor applications, such as large liquid crystal display devices and digital signage liquid crystal display devices. .

  A technique for improving the interlayer adhesion between the cellulose ester-based protective film and the hard coat layer is disclosed in Patent Document 2, for example. Patent Document 2 is cured with a component containing a polyfunctional (meth) acrylic monomer, a (meth) acrylic monomer having a hydroxy group (hydroxyl group), a photoradical polymerization initiator, and a fluorine-containing compound having a polymerizable group. This is a hard coat film in which the surface free energy of the hard coat layer is 20 mN / m or less, and the film thickness of the hard coat layer is controlled to 5 to 25 μm.

  In the technique of Patent Document 2, although the interlayer adhesion between the protective film and the hard coat layer before the weather resistance test is improved to some extent, the interlayer adhesion after the weather resistance test has no improvement effect, and the contents related to the present invention are as follows. No mention or mention is made.

JP 2008-69225 A JP 2009-263600 A

  The present invention has been made in view of the above problems and situations, and the solution is to provide a hard coat film that improves the interlayer adhesion between the protective film and the hard coat layer after the weather resistance test. is there. Moreover, it is providing the polarizing plate provided with it, and a liquid crystal display device.

  As a result of intensive studies to solve the above problems, the inventor has controlled the ratio of the arithmetic average roughness Ra of the hard coat layer of the hard coat film and the average length (RSm) of the contour curve elements to a specific range, and By preparing a hard coat film under conditions that allow the arithmetic average roughness Ra of the hard coat layer to be controlled within the above range, the coating resin that forms the hard coat layer is controlled to have a viscosity that easily penetrates into the substrate. As soon as the coating resin penetrates into the material and the adhesive effect is improved by the anchor effect, the present invention has been achieved.

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

1. A hard coat film having a hard coat layer on a base film, wherein the arithmetic average roughness Ra of the hard coat layer is in the range of 2 to 20 nm, and the arithmetic average roughness Ra and the average of the contour curve elements The ratio (Ra / RSm) with length RSm exists in the range of 5 * 10 < ^-5 > ^-3 * 10 < ^-4 >, The hard coat film characterized by the above-mentioned.

  2. 2. The hard coat film according to item 1, wherein the arithmetic average roughness Ra of the hard coat layer is in the range of 4 to 20 nm.

  3. 3. The hard coat film according to item 1 or 2, wherein the hard coat layer substantially does not contain fine particles.

  4). The hard coat film according to any one of items 1 to 3, wherein the hard coat layer has protrusions, and the protrusions are irregular in shape.

  5. The absolute value | Hh−Hf | of the difference between the haze value (Hh) of the hard coat film and the haze value (Hf) of the base film is in the range of 0.0 to 0.8%. The hard coat film according to any one of items 1 to 4 above.

  6). The hard coat layer contains an actinic radiation curable resin, and the viscosity of the actinic radiation curable resin is in the range of 30 to 3000 mPa · s. Hard coat film as described in any one of these.

7. The hard coat film according to any one of items 1 to 6, wherein tan δ in the film width direction of the base film satisfies the following relational expression.
Relational expression: 0.5 ≧ tan δ ₋₄₀ / tan δ _peak ≧ 0.24
Here, tan δ _peak represents the maximum value of tan δ values measured in the range of 25 to 210 ° C., and tan δ ₋₄₀ represents the value of tan δ at a temperature of −40 ° C. when tan δ _peak is indicated.

  8). A polarizing plate comprising the hard coat film according to any one of items 1 to 7 above.

  9. A liquid crystal display device comprising the hard coat film according to any one of items 1 to 7 above.

  By the above means of the present invention, it is possible to provide a hard coat film in which the interlayer adhesion between the protective film after the weather resistance test and the hard coat layer is improved. Moreover, the polarizing plate provided with the same and a liquid crystal display device can be provided.

Explanatory drawing of the protrusion concerning this invention Schematic diagram of polarizing plate according to the present invention Schematic diagram for evaluating the durability test of polarizing plates

The hard coat film of the present invention is a hard coat film having a hard coat layer on a base film, wherein the arithmetic average roughness Ra of the hard coat layer is in the range of 2 to 20 nm, and the arithmetic average roughness The ratio (Ra / RSm) between the height Ra and the average length RSm of the contour curve elements is in the range of 5 × 10 ^{−5 to} 3 × 10 ⁻⁴ . This feature is a technical feature common to the inventions according to claims 1 to 9.

  As an embodiment of the present invention, it is preferable that the arithmetic average roughness Ra of the hard coat layer is in the range of 4 to 20 nm from the viewpoint of manifesting the effects of the present invention. Furthermore, it is preferable that the hard coat layer does not substantially contain fine particles. In particular, it is preferable that the hard coat layer has a protrusion and the shape of the protrusion is irregular.

  In the present invention, the absolute value | Hh−Hf | of the difference between the haze value (Hh) of the hard coat film and the haze value (Hf) of the base film is in the range of 0.0 to 0.8%. Preferably there is. Moreover, it is preferable that the said hard-coat layer contains actinic radiation curable resin, and the viscosity of the said actinic radiation curable resin is in the range of 30-3000 mPa * s. Furthermore, it is preferable that tan δ in the film width direction of the base film satisfies the relational expression.

  The hard coat film of this invention can be used suitably for a polarizing plate and a liquid crystal display device.

  Hereinafter, the present invention, its components, and modes and modes for carrying out the present invention will be described in detail. In addition, in this application, "-" is used in the meaning which includes the numerical value described before and behind that as a lower limit and an upper limit.

<Surface shape>
The hard coat film of the present invention is a hard coat film having a hard coat layer on a base film, wherein the arithmetic average roughness Ra of the hard coat layer is in the range of 2 to 20 nm, and the arithmetic average roughness The ratio (Ra / RSm) between the height Ra and the average length RSm of the contour curve elements is in the range of 5 × 10 ^{−5 to} 3 × 10 ⁻⁴ .

  The arithmetic average roughness Ra is a value measured with an optical interference type surface roughness meter (RST / PLUS, manufactured by WYKO) based on the provisions of JIS B0601: 2001. The arithmetic average roughness Ra is 2 to 20 nm, more preferably 4 to 20 nm.

  Also, the average length RSm of the contour curve element is a value measured with an optical interference type surface roughness meter (RST / PLUS, manufactured by WYKO) based on the provisions of JIS B0601: 2001, similarly to the arithmetic average roughness Ra. It is. RSm is preferably 3 to 80 μm, more preferably 5 to 70 μm.

By controlling the ratio (Ra / RSm) of the arithmetic average roughness Ra measured as described above and the average length RSm of the contour curve element to a range of 5 × 10 ^{−5 to} 3 × 10 ⁻⁴ , Interlayer adhesion after the weather resistance test with the hard coat layer is improved.

  The hard coat layer according to the present invention preferably has protrusions on the hard coat layer in order to obtain an arithmetic average roughness Ra (hereinafter also simply referred to as “Ra”) within the above range. The height of the protrusion shape is 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 height and width of the protrusion shape can be obtained from cross-sectional observation. FIG. 1 is an explanatory view of the protrusion. As shown in FIG. 1, the center line a is drawn on the cross-sectional observation image, and the distance between the two intersections of the lines b and c and the center line a forming the mountain ridge is defined as the protrusion size width t and did. Further, the distance from the summit to the center line a is obtained as the height h of the protrusion size.

Further, the number of protrusions of the hard coat layer is preferably 500 to 200000 pieces / mm ² . Specifically, it can be measured by the following method.

  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 is performed 10 times, and the number of protrusions of the hard coat layer of the hard coat film can be determined from the average value of 10 times. As the number of protrusions, protrusions having a height of 3 nm or more are counted from the average line of the roughness curve.

  As a method of forming the protrusion shape, a method of adding fine particles, a method of forming a protrusion on the surface by pressing a mold, and a processing temperature in the decreasing rate drying section in the drying process of the hard coat coating composition are controlled to a high temperature condition. Examples include methods such as the method of forming protrusions on the surface by pressing a mold and the method of regularly forming protrusions on the surface, after the weather resistance test between the protective film and the hard coat layer. A sufficient effect for adhesion cannot be obtained.

  In the present invention, as a method of forming the protrusion shape, it is possible to use a method of controlling the treatment temperature in the drying rate reduction section in the drying process of the hard coat coating composition to a high temperature condition, and the interlayer adhesion after the weather resistance test, production From the viewpoints of reproducibility and reproducibility. By controlling the rate-of-decreasing drying section at a high temperature, convection occurs in the resin coating film, resulting in a non-uniform surface state, which is cured in this non-uniform surface state and a coating film is formed. It is believed that surface irregularities can be obtained.

  Therefore, in the present invention, when the above-described method for controlling the drying process is used as a method for forming the protrusion shape, the hard coat layer according to the present invention substantially contains fine particles. It becomes the aspect which does not contain.

  In addition, the “irregular protrusion shape” of the present invention refers to protrusions having various shapes whose shapes and sizes are not fixed, and are not protrusions whose surface unevenness has a regular shape due to embossing. Although not limited thereto, for example, protrusions having different widths and heights such as (a) and (b) shown in FIG. 1 are exemplified as irregularly shaped protrusions. The “irregular arrangement” means that the irregularly-protruding protrusions are not regularly arranged (for example, at regular intervals), but are irregularly arranged at random intervals, It may be isotropic or anisotropic.

<Haze>
The haze value (Hh) of the hard coat film of the present invention is preferably 1.5% or less, more preferably 1% or less from the viewpoint of clearness. In addition, when the haze value (Hh) of the hard coat film is less than 0.2%, the design is difficult in terms of the handleability of the hard coat film. Further, the absolute value | Hh−Hf | of the difference between the haze value (Hh) of the hard coat film and the haze value (Hf) of the base film is set within a range of 0.0 to 0.8%. This is preferable because sufficient luminance and high contrast can be obtained when used outdoors such as a liquid crystal display device or digital signage.

  In order to control the haze value of the hard coat layer, adjustment of the resin constituting the hard coat layer, the type and amount of the additive, the content ratio of the resin and solvent of the hard coat layer coating composition, and the reduction rate of the drying process This can be achieved under the processing temperature conditions in the drying section. In addition, since the arithmetic average roughness Ra of the hard coat layer also affects the haze value as surface haze, it is effective to control the shape and number of the protrusions.

<Hard coat film>
The hard coat film of the present invention is composed of at least a base film and a hard coat layer. The hard coat layer contains an actinic radiation curable resin, and is an actinic ray (also referred to as an actinic energy ray) such as an ultraviolet ray or an electron beam. ) It is preferably a layer mainly composed of a resin that is cured through a crosslinking reaction upon irradiation.

  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, 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 according to the present invention may contain a monofunctional acrylate. When monofunctional acrylate is used, polyfunctional acrylate: monofunctional acrylate = 80: 20 to 99: 2 is preferable in terms of mass ratio of polyfunctional acrylate to monofunctional acrylate.

  Monofunctional acrylates include isobornyl acrylate, 2-hydroxy-3-phenoxypropyl acrylate, isostearyl acrylate, benzyl acrylate, ethyl carbitol acrylate, phenoxyethyl acrylate, lauryl acrylate, isooctyl acrylate, tetrahydrofurfuryl acrylate, behenyl Examples include acrylate, 4-hydroxybutyl acrylate, 2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate, and cyclohexyl acrylate. Monofunctional acrylates can be obtained from Shin Nakamura Chemical Co., Ltd., Osaka Organic Chemical Industry Co., Ltd., and the like. In the present invention, actinic radiation curable resins other than the above-described polyfunctional acrylates and monofunctional acrylates may be used singly or in combination. The viscosity at 25 ° C. of the actinic radiation curable resin alone or in combination of two or more is preferably from 30 mPa · s to 3000 mPa · s, and more preferably from 30 mPa · s to 2000 mPa · s. By using such a low-viscosity resin, sufficient fluidity of the resin composition can be obtained in the drying step, so that a protrusion shape is easily formed on the hard coat layer. Moreover, if it is an actinic radiation curable resin with a viscosity of 30 mPa · s or more, sufficient curability is obtained, and if it is an actinic radiation curable resin with a viscosity of 3000 mPa · s or less, sufficient flow of the resin composition in the drying step. Therefore, it is easy to form an uneven shape on the hard coat layer surface. The viscosity is a value measured using a B-type viscometer at 25 ° C. Examples of the low viscosity resin include glycerin triacrylate, pentaerythritol triacrylate, and pentaerythritol tetraacrylate.

  By using such a low-viscosity resin, sufficient fluidity of the resin composition can be obtained in the drying step, so that a protrusion shape is easily formed on the hard coat layer. In addition, the said viscosity is the value measured on 25 degreeC conditions using the B-type viscometer.

  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. .

  Further, the hard coat layer according to the present invention is provided by applying a hard coat layer coating composition diluted with a solvent that swells or partially dissolves the base film, dried, and cured on the base film by the following method. It is preferable from the point that a protrusion shape is easily obtained in the hard coat layer. As a solvent that swells or partially dissolves the base film, a solvent containing a ketone and / or acetate is preferable. Moreover, 0.1-40 micrometers is suitable for an application quantity as a wet film thickness, Preferably, it is 0.5-30 micrometers. The dry film thickness is from 0.1 to 30 μm, preferably from 1 to 20 μm, particularly preferably from 4 to 15 μm.

  The hard coat layer is applied using a known coating method such as a gravure coater, dip coater, reverse coater, wire bar coater, die coater, ink jet method, and the like. It can be formed by drying, UV curing treatment, and if necessary, heat treatment for UV curing. Drying is preferably performed at a high temperature of 70 ° C. or more in the decreasing rate drying section, more preferably 80 ° C. or more, and particularly preferably 90 ° C. or more. Most preferably, the temperature in the reduced rate drying section is in the range of 95 ° C to 120 ° C. By controlling the temperature of the decreasing rate drying section within this range, the arithmetic average roughness Ra of the hard coat layer can be easily controlled within the range of the present invention. It is inferred that convection is positively generated in the resin coating by forming the reduced rate drying section at a high temperature, and as a result, a protrusion shape is formed on the surface of the hard coat layer.

  In general, it is known that the drying process changes from a constant state to a gradually decreasing state when drying starts. The decreasing section is called the decreasing rate drying section. In the constant rate drying section, the amount of heat flowing in is all consumed for solvent evaporation on the coating film surface, and when the solvent on the coating film surface decreases, the evaporation surface moves from the surface to the inside and enters the decreasing rate drying section. Thereafter, the temperature of the coating film surface rises and approaches the hot air temperature, so that the temperature of the ultraviolet curable resin composition rises, the resin viscosity decreases, and the fluidity increases.

  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 50 to 1000 mJ / cm ² , preferably 50 to 300 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 conveying 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. Activators and fluorine-siloxane graft polymers may be included. The fluorine-siloxane graft polymer refers to a copolymer polymer obtained by grafting polysiloxane and / or organopolysiloxane containing siloxane and / or organosiloxane alone on at least a fluorine-based resin. Examples of commercially available products include ZX-022H, ZX-007C, ZX-049, and ZX-047-D manufactured by Fuji Kasei Kogyo Co., Ltd. The silicone-based surfactant is a surfactant obtained by substituting a part of the methyl group of the silicone oil with a hydrophilic group. Examples of the hydrophilic group include polyether, polyglycerin, pyrrolidone, betaine, sulfate, phosphate, and quaternary salt. Specific products of silicone surfactants include, for example, SH200, BY16-873, PRX413 (dimethylsilicone oil; manufactured by Toray Dow Corning Silicone Co., Ltd.), SH203, SH230, SF8416 (alkyl-modified silicone oil; Toray Dow Corning Silicone Co., Ltd.), SF8417, BY16-208, BY16-209, BY16-849, BY16-872, FZ-2222, FZ-2207 (dimethylpolysiloxane / polyethylene oxide linear block copolymer; Japan) Unicar Co., Ltd. FZ series), KF-101, KF-102, KF-105 (epoxy-modified silicone oil; manufactured by Shin-Etsu Chemical Co., Ltd.), BYK-UV3500, BYK-UV3510, BYK-333, BYK- 31, BYK-337 - but (polyether-modified silicone oil Big Chemi Japan Co., Ltd.) without limitation. Moreover, it is preferable to add these components in 0.01-5 mass% with respect to the solid content component in a coating liquid.

  The hard coat layer may be a single layer or a plurality of layers. In order to easily control the hard coat properties, haze, and arithmetic surface roughness Ra of the hard coat layer, the hard coat layer may be divided into two or more layers.

  The thickness of the uppermost layer when two or more layers are provided is preferably in the range of 0.05 to 2 μm. 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 3H or higher. If it is 3H or more, it is not only difficult to be scratched in the polarizing plate forming step of the liquid crystal display device, but 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 according to the present invention is preferably easy to produce, easy to adhere to the hard coat layer, and optically isotropic. Moreover, in this invention, a base film is 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 Polyether 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.

  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, cellulose ester films are particularly preferred from the viewpoint of production, cost, isotropic properties, and adhesiveness (saponification suitability).

  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 Abbe refractometer 2T manufactured by Atago Co., Ltd.

  The base film has the following relationship with tan δ measured by changing the temperature from 25 ° C. to 210 ° C. at a humidity of 55% RH in the width direction of the film. It is preferable from the point of exhibiting.

0.5 ≧ tan δ ₋₄₀ / tan δ _peak ≧ 0.24
Here, “tan δ _peak ” refers to the maximum value when the tan δ value is measured while changing the temperature from 25 ° C. to 210 ° C., and “tan δ ₋₄₀ ” refers to 40 tan from the temperature when tan δ _peak is indicated. It means a value of tan δ at a temperature lower by ℃, that is, a temperature of -40 ℃.

  By making the balance of the storage elastic modulus and the loss elastic modulus with respect to the tan δ in the film width direction of the base film, that is, the temperature within the above range, the object effect of the present invention is more effectively exhibited. The tan δ was measured, for example, by using a sample that had been conditioned for 24 hours in an atmosphere of 23 ° C. and 55% RH and increasing the temperature at a humidity of 55% RH under the following conditions or setting the temperature.

Measuring device: RSA III manufactured by TI Instruments
Sample: width 5 mm, length 50 mm (gap set to 20 mm)
Measurement conditions: Tensile mode Measurement temperature: 25-210 ° C or 40 ° C
Temperature rising condition: 5 ° C / min
Frequency: 1Hz
<Cellulose ester film>
A typical example of a resin film preferable as the substrate film according to the present invention is a cellulose ester film.

  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, a mixed fatty acid such as cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, etc. Esters can be used.

  Particularly preferably used lower fatty acid esters of cellulose 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 the productivity is lowered.

  The cellulose triacetate has an acetyl group substitution degree of 2.80 to 2.95, a number average molecular weight (Mn) of 125,000 or more and less than 155000, a weight average molecular weight (Mw) of 265,000 or more and less than 310,000, Mw Cellulose triacetate A / Mn of 1.9 to 2.1, acetyl group substitution degree of 2.75 to 2.90, number average molecular weight (Mn) of 155,000 or more and less than 180,000, Mw is 290000 or more and less than 360,000 Mw / Mn preferably contains cellulose triacetate B which is 1.8 to 2.0.

  Further, when cellulose triacetate A and cellulose triacetate B are used in combination, it is preferable that the mass ratio is in the range of cellulose triacetate A: cellulose triacetate B = 100: 0 to 20:80.

  Preferred cellulose esters other than cellulose triacetate have an acyl group having 2 to 4 carbon atoms as a substituent, the substitution degree of acetyl group is X, and the substitution degree of propionyl group or butyryl group is Y, It is a cellulose ester containing the cellulose ester which satisfy | fills (I) and (II) simultaneously.

Formula (I) 2.6 ≦ X + Y ≦ 3.0
Formula (II) 0 ≦ X ≦ 2.5
In particular, cellulose acetate propionate is preferably used, and among them, 1.9 ≦ X ≦ 2.5 and 0.1 ≦ Y ≦ 0.9 are preferable.

  The number average molecular weight (Mn) and molecular weight distribution (Mw) of the cellulose ester can be measured using high performance liquid chromatography. 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 according to the present invention contains a thermoplastic acrylic resin and a cellulose ester resin, and the content mass ratio of the thermoplastic acrylic resin and the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = 95: 5 to You may use the film which is 50:50.

  The acrylic resin includes a methacrylic resin. Although it does not restrict | limit especially as an 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 acrylic resin can be measured by gel permeation chromatography 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.), Dialal BR52, BR80, BR83, BR85, BR88 (Mitsubishi Rayon Co., Ltd.), KT75 (Electric Chemical Co., Ltd.), etc. are mentioned. . Two or more acrylic resins can be used in combination. As the acrylic resin, a graft copolymer obtained by grafting a (meth) acrylic resin to a copolymer of a (meth) acrylic rubber and an aromatic vinyl compound described in JP-A-2009-84574 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.

  The total mass of the acrylic resin and the cellulose ester resin in the base film is preferably 55% by mass or more of the base film, more preferably 60% by mass or more, and particularly preferably 70% by mass or more.

  The base film may be configured to contain resins and additives other than thermoplastic acrylic resins and cellulose ester resins.

<Acrylic particles>
The base film may contain acrylic particles because it is excellent in improving brittleness. 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 acrylic particles are not particularly limited, but are preferably acrylic particles having a layer structure of two or more layers, and particularly preferably a multilayer structure acrylic granular composite. Examples of commercially available acrylic granular composites that are multi-layer structured polymers include, for example, “Metablene” manufactured by Mitsubishi Rayon Co., “Kaneace” manufactured by Kaneka Chemical Co., Ltd., “Paralloid” manufactured by Kureha Chemical Co., Ltd., Rohm and Examples include “Acryloid” manufactured by Haas, “Staffyroid” manufactured by Gantz Kasei Kogyo, and “Parapet SA” manufactured by Kuraray, and these may be used alone or in combination of two or more.

  Moreover, when adding an acrylic particle to a base film, it is preferable at the point which obtains a film with high transparency that the refractive index of the mixture of an acrylic resin and a cellulose-ester resin and the refractive index of an acrylic particle are near. Specifically, the refractive index difference between the acrylic particles and the acrylic resin is preferably 0.05 or less, more preferably 0.02 or less, and particularly preferably 0.01 or less.

  The acrylic fine particles are acrylic fine particles: acrylic resin and cellulose ester resin total mass = 0.5: 100 to 30: 100 with respect to the total mass of the acrylic resin and the cellulose ester resin constituting the base film. By making it contain in a range, it is preferable from the point by which a target effect is exhibited more preferable, More preferably, it is the range of 1.0: 100-15: 100 of acrylic fine particles: total mass of acrylic resin and cellulose-ester resin.

<Other additives>
A plasticizer can also be used in combination with the base film in order to improve the fluidity and flexibility of the composition. 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. It can be applied to a wide range of uses by selecting or using these plasticizers according to the use.

  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 plasticizer is preferably an aromatic terminal ester plasticizer. The aromatic terminal ester plasticizer is preferably an ester compound having a structure obtained by reacting phthalic acid, adipic acid, at least one benzene monocarboxylic acid and at least one alkylene glycol having 2 to 12 carbon atoms. As long as it has an adipic acid residue and a phthalic acid residue as the structure of such a compound, when an ester compound is produced, it may be reacted as an acid anhydride or esterified product of dicarboxylic acid.

  Examples of the benzene monocarboxylic acid component include benzoic acid, para-tert-butylbenzoic acid, orthotoluic acid, metatoluic acid, p-toluic acid, dimethylbenzoic acid, ethylbenzoic acid, normal propylbenzoic acid, aminobenzoic acid, acetoxybenzoic acid and the like. Most preferred is benzoic acid. Moreover, these can each be used as a 1 type, or 2 or more types of mixture.

  Examples of the alkylene glycol component having 2 to 12 carbon atoms include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,2-propanediol, 2-methyl 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 2,2-diethyl-1, 3-propanediol (3,3-dimethylolpentane), 2-n-butyl-2-ethyl-1,3-propanediol (3,3-dimethylolheptane), 3-methyl-1,5-pentanediol 1 , 6-hexanediol, 2,2,4-trimethyl 1,3-pentanediol, 2-ethyl 1,3-hexanediol, - methyl 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,12-octadecane diol. Among these, 1,2-propylene glycol is particularly preferable. These glycols may be used as one kind or a mixture of two or more kinds.

  The aromatic terminal ester plasticizer may be of an oligoester type or a polyester type, and the molecular weight is preferably in the range of 100 to 10,000, but is preferably in the range of 350 to 3000. The acid value is 1.5 mgKOH / g or less, the hydroxy group (hydroxyl group) value is 25 mgKOH / g or less, more preferably the acid value is 0.5 mgKOH / g or less, and the hydroxy group (hydroxyl group) value is 15 mgKOH / g or less. is there. 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. Specific examples include the following compounds, but are not limited thereto.

  Furthermore, the base film may contain a sugar ester compound. The sugar ester compound is a compound obtained by esterifying all or part of the OH group of a sugar such as the following monosaccharide, disaccharide, trisaccharide or oligosaccharide, specifically, a compound represented by the general formula (1) Etc.

In the formula, R _{1 to} R ₈ represent a substituted or unsubstituted alkylcarbonyl group or a substituted or unsubstituted arylcarbonyl group, and R _{1 to} R ₈ may be the same or different. .

Although the compound shown by General formula (1) below is shown more concretely (compound 1-1-compound 1-23), it is not limited to these. In addition, as a preferable specific example of a compound represented by General formula (1), the compound shown in the following table is mentioned. In addition, R described in the following table represents any one of R _{1 to} R ₈ . As the substituent for the alkylcarbonyl group and the arylcarbonyl group, substituents such as a phenyl group and an alkoxy group included in the alkylcarbonyl group and the arylcarbonyl group shown in the following table are preferable.

  Furthermore, the base film preferably contains an ultraviolet absorber. Examples of the ultraviolet absorber include benzotriazole, 2-hydroxybenzophenone, and salicylic acid phenyl ester. 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, 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 the base film has a defect of 5 μm or more in diameter in the film plane of 1 piece / 10 cm square or less. 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.

  When the number of defects is greater than 1/10 cm square, for example, when the film is tensioned during processing in a later process, the film may break with the defects as a starting point, and productivity may decrease. Moreover, when the diameter of a defect becomes 5 micrometers or more, it can confirm visually by polarizing plate observation etc., and when used as an optical member, a bright spot may arise.

  Moreover, even when it cannot be visually confirmed, when a hard coat layer or the like is formed on the film, the coating agent may not be formed uniformly, resulting in a defect (missing coating). 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 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. The thickness of the film can be appropriately selected depending on the application.

  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, it 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. Moreover, after the film-forming material is heated to exhibit its fluidity, a method of extrusion film formation on a drum or an endless belt is also included as a melt casting film formation 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 mass in total of three types of acrylic resin, cellulose ester resin, and acrylic particles. It is preferable that the dope composition is dissolved in%.

  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)
The base film can be produced by a solution casting method. In the solution casting method, a step of preparing a dope by dissolving a resin and an additive in a solvent, a step of casting the dope on a belt-like or drum-like metal support, and a step of drying the cast dope as a web , Peeling from the metal support, stretching or maintaining the width, further drying, and winding the finished film.

  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 a 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 warm 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 target temperature is used while preventing foaming. .

  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 step, generally, a roll drying method (a method in which webs are alternately passed through a plurality of rolls arranged above and below) and a method in which the web is dried while being conveyed by a tenter method are employed.

(Stretching process)
In the stretching step, the film can be sequentially or simultaneously stretched in the longitudinal direction (MD direction) and the width direction (TD direction) of the film. It is preferable that the draw ratios in the biaxial directions perpendicular to each other are finally in the range of 1.0 to 2.0 times in the MD direction and 1.07 to 2.0 times in the TD direction. It is preferable to carry out within a range of 1.0 to 1.5 times and 1.07 to 2.0 times in the TD direction. For example, a method in which peripheral speed differences are applied to a plurality of rolls and a roll peripheral speed difference is used to stretch in the MD direction, both ends of the web are fixed with clips and pins, and the distance between the clips and pins is increased in the traveling direction. And a method of stretching in the MD direction, a method of stretching in the transverse direction and stretching in the TD direction, a method of stretching in the MD / TD direction simultaneously and stretching in both the MD / TD directions, and the like.

  These width maintenance or width direction stretching in the film forming step is preferably performed by a tenter, and may be a pin tenter or a clip tenter.

  The film transport tension in the film forming process such as in the tenter depends on the temperature, but is preferably 120 N / m to 200 N / m, and more preferably 140 N / m to 200 N / m. 140 N / m to 160 N / m is most preferable.

  When stretching, assuming that the glass transition temperature of the substrate film is Tg, (Tg-30) to (Tg + 100) ° C., more preferably (Tg-20) to (Tg + 80) ° C., and more preferably (Tg-5) to (T Tg + 20) ° C.

  The Tg of the base film can be controlled by the material type constituting the film and the ratio of the constituting materials. In the application of the present invention, the Tg when the film is dried is preferably 110 ° C. or higher, more preferably 120 ° C. or higher.

  Accordingly, the glass transition temperature is preferably 190 ° C. or lower, more preferably 170 ° C. or lower. At this time, the Tg of the film can be determined by the method described in JIS K7121.

  It is preferable that the temperature at the time of stretching is 150 ° C. or more and the stretching ratio is 1.15 times or more because the surface is appropriately roughened. Roughening the film surface is preferable because it improves not only the slipperiness but also the surface processability, particularly the adhesion of the hard coat layer. The arithmetic average roughness Ra is preferably 2.0 nm to 4.0 nm, more preferably 2.5 nm to 3.5 nm.

(Melting method)
The base film may be formed by a melt film forming method. The melt film-forming method refers to heating and melting a composition containing an additive such as a resin and a plasticizer to a temperature exhibiting fluidity, and then casting a melt containing a fluid cellulose ester.

  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 molding methods, the melt extrusion method is preferable from the viewpoint of mechanical strength and surface accuracy. 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 using a feeder, kneaded using a single or twin screw extruder, and extruded from a die into a strand. It can be done by 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 uniaxial or biaxial extruder, the pellets are melted at a temperature of about 200 to 300 ° C., filtered through a leaf disk type filter to remove foreign matter, and then formed into a film from a T die. The film is cast and the film is nipped by a cooling roll and an elastic touch roll, and solidified on the cooling roll.

  When introducing into the extruder from the supply hopper, it is preferable to prevent oxidative decomposition or the like under vacuum, reduced pressure, or inert gas atmosphere.

  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 stainless steel fiber sintered filter is a united stainless steel fiber body that is intricately intertwined and compressed, and the contact points are sintered and integrated. The density of the fiber is changed depending on the thickness of the fiber and the amount of compression, and the filtration accuracy is improved. Can be adjusted.

  Additives such as plasticizers and particles may be mixed with the resin in advance, or may be kneaded in the middle of the extruder. In order to add uniformly, it is preferable to use a mixing apparatus such as a static mixer.

  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.

  The elastic touch roll is also called a pinching rotator. As the elastic touch roll, a touch roll disclosed in registered patent 3194904, registered patent 3422798, Japanese Patent Laid-Open No. 2002-36332, Japanese Patent Laid-Open No. 2002-36333, or the like can be preferably used. 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 of the present invention can be provided with functional layers such as a back coat layer and an antireflection layer.

<Back coat layer>
In the hard coat film of the present invention, a back coat layer may be provided 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 of the present invention 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, and 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 layer structure of four or more layers 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 inside 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 of the present invention using the hard coat film of the present invention will be described. The polarizing plate of the present invention is particularly excellent in deformation failure resistance when stored under high temperature and high humidity. In addition, by using the polarizing plate of the present invention for an image display device such as a liquid crystal display device, the visibility is excellent, and the deformation failure prevention performance and the visibility are both compatible when stored under high temperature and high humidity. It can be seen that it has performance.

  The polarizing plate can be produced by a general method. The back surface side of the hard coat film of the present invention is subjected to alkali saponification treatment, and a completely hardened 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 bond 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 side of the hard coat film of the present invention contains the cellulose triacetate film, which is the base film described above, a thermoplastic acrylic resin and a cellulose ester resin, and the thermoplastic acrylic film. It is preferable to use a protective film in which the mass ratio of the resin to the cellulose ester resin is thermoplastic acrylic resin: cellulose ester resin = 95: 5 to 50:50. Details of the configuration are as described above, and specific examples include 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-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 (manufactured by Konica Minolta Opto), Zeonore Film (manufactured by Nippon Zeon Co., Ltd.), Arton Film (manufactured by JSR Co., Ltd.) and the like can be 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 of 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 of the present invention into a display device, an image display device having excellent visibility can be produced.

  The hard coat film of the present invention is incorporated in a polarizing plate, and is a reflection type, transmission type, transflective liquid crystal display device or TN type, STN type, OCB type, HAN type, VA type (PVA type, MVA type), IPS type. It is preferably used in liquid crystal display devices of various driving systems such as 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 triacetate film 1)>
<Preparation of ester compound 1>
251 g of 1,2-propylene glycol, 278 g of phthalic anhydride, 91 g of adipic acid, 610 g of benzoic acid, 0.191 g of tetraisopropyl titanate as an esterification catalyst, 2 L four-neck equipped with thermometer, stirrer, and slow cooling tube The flask is charged and gradually heated with stirring until it reaches 230 ° C. in a nitrogen stream. The ester compound 1 was obtained by making it dehydrate-condense for 15 hours, and depressurizingly distilling unreacted 1, 2- propylene glycol at 200 degreeC after completion | finish of reaction. The acid value was 0.10 and the number average molecular weight was 450.

<Preparation of base film 1>
(Silicon dioxide dispersion)
Aerosil R812 (manufactured by Nippon Aerosil Co., Ltd.) 10 parts by mass (average diameter of primary particles 7 nm)
90 parts by mass of ethanol or more was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. 88 parts by mass of methylene chloride was added to the silicon dioxide dispersion while stirring, and the mixture was stirred and mixed for 30 minutes with a dissolver to prepare a silicon dioxide dispersion dilution. It filtered with the fine particle dispersion | distribution dilution liquid filter (Advantech Toyo Co., Ltd .: Polypropylene wind cartridge filter TCW-PPS-1N).

(Dope composition)
90 parts by mass of cellulose triacetate A1 (cellulose triacetate synthesized from linter cotton, acetyl group substitution degree 2.88, Mn = 14000)
Ester compound 1 10 parts by weight Tinuvin 928 (manufactured by BASF Japan Ltd.) 2.5 parts by weight Silicon dioxide dispersion diluent 4 parts by weight Methylene chloride 432 parts by weight Ethanol 38 parts by weight The above is put into a sealed container, heated and stirred. While being completely dissolved, Azumi Filter Paper No. No. 24 was used for filtration to prepare a dope solution.

  Next, the belt casting apparatus was used to uniformly cast on a stainless steel band support. With the stainless steel band support, the solvent was evaporated until the residual solvent amount reached 100%, and the stainless steel band support was peeled off. The cellulose ester film web was evaporated at 35 ° C., slit to 1.65 m width, and stretched 1.3 times in the TD direction (film width direction) with a tenter, and the MD direction draw ratio was 1.01 times. While stretching, the film was dried at a drying temperature of 160 ° C. The residual solvent amount at the start of drying was 20%. Then, after drying for 15 minutes while transporting the inside of a drying device at 120 ° C. with a number of rolls, slitting to a width of 1.49 m, applying a knurling process with a width of 15 mm and a height of 10 μm at both ends of the film, and winding it around a winding core The base film 1 was obtained. The residual solvent amount of the base film was 0.2%, the film thickness was 40 μm, and the number of turns was 3900 m.

<Preparation of hard coat film 1>
On the substrate film 1 (cellulose triacetate film 1) produced above, the following hard coat layer composition 1 filtered through a polypropylene filter having a pore diameter of 0.4 μm was used to prepare the cellulose triacetate film 1 using a micro gravure coater. After applying to the surface and drying at a constant rate drying section temperature of 95 ° C and a decreasing rate drying section temperature of 95 ° C, irradiation is performed using an ultraviolet lamp while purging with nitrogen so that the oxygen concentration becomes 1.0 vol% or less. The coating layer was cured with an illuminance of 100 mW / cm ² and an irradiation amount of 0.3 J / cm ² to form a hard coat layer 1 having a dry film thickness of 7 μm. Winding and roll-shaped hard coat film 1 were produced.

[Hard Coat Layer Composition 1]
<Preparation of fluorine-siloxane graft polymer>
Below, the commercial name of the raw material used for preparation of the fluorine-siloxane graft polymer is shown.

Radical polymerizable fluororesin (A): Cefal coat CF-803 (hydroxy group (hydroxyl group) value 60, number average molecular weight 15,000; manufactured by Central Glass Co., Ltd.)
One-end radical polymerizable polysiloxane (B): Silaplane FM-0721 (number average molecular weight 5,000; manufactured by Chisso Corporation)
Radical polymerization initiator: Perbutyl O (t-butylperoxy-2-ethylhexanoate; manufactured by NOF Corporation)
Curing agent: Sumidur N3200 (biuret type prepolymer of hexamethylene diisocyanate; manufactured by Sumika Bayer Urethane Co., Ltd.)
(Synthesis of radical polymerizable fluororesin)
In a glass reactor equipped with a mechanical stirrer, thermometer, condenser and dry nitrogen gas inlet, cefal coat CF-803 (1554 parts by mass), xylene (233 parts by mass), and 2-isocyanatoethyl methacrylate (6 3 parts by mass) and heated to 80 ° C. in a dry nitrogen atmosphere. After reacting at 80 ° C. for 2 hours and confirming that the absorption of isocyanate disappeared by the infrared absorption spectrum of the sampled material, the reaction mixture was taken out to obtain 50% by mass of a radically polymerizable fluororesin via a urethane bond. .

(Preparation of fluorine-siloxane graft polymer)
In a glass reactor equipped with a mechanical stirrer, thermometer, condenser and dry nitrogen gas inlet, the above synthesized radical polymerizable fluororesin (26.1 parts by mass), xylene (19.5 parts by mass), acetic acid n-butyl (16.3 parts by mass), methyl methacrylate (2.4 parts by mass), n-butyl methacrylate (1.8 parts by mass), lauryl methacrylate (1.8 parts by mass), 2-hydroxyethyl methacrylate (1 .8 parts by mass), FM-0721 (5.2 parts by mass), and perbutyl O (0.1 parts by mass) were heated to 90 ° C. in a nitrogen atmosphere, and held at 90 ° C. for 2 hours. Perbutyl O (0.1 part) was added, and the solution was further maintained at 90 ° C. for 5 hours to obtain a 35 mass% fluorine-siloxane graft polymer solution having a weight average molecular weight of 171,000. The weight average molecular weight was determined by GPC. The mass% of the fluorine-siloxane graft polymer was determined by HPLC (liquid chromatography).

Pentaerythritol tri / tetraacrylate (NK ester A-TMM-3L, manufactured by Shin-Nakamura Chemical Co., Ltd.) 100 parts by mass Irgacure 184 (manufactured by BASF Japan Ltd.) 5 parts by mass Fluorine-siloxane graft polymer (35% by mass) 2 parts by mass Propylene glycol monomethyl ether 10 parts by mass Methyl acetate 45 parts by mass Methyl ethyl ketone 45 parts by mass In addition, in Table 1, pentaerythritol tri / tetraacrylate, which is a polyfunctional acrylate, is indicated as PETA.

<Preparation of hard coat film 2>
In the production of the hard coat film 1, a hard coat film 2 was produced in the same manner except that the temperature at which the reduction rate drying interval was changed to 90 ° C.

<Preparation of hard coat film 3>
In the production of the hard coat film 1, the hard coat film 3 was produced in the same manner, except that the temperature of the decreasing rate drying section was changed to 100 ° C.

<Preparation of hard coat film 4>
In the production of the hard coat film 1, the hard coat film 4 was produced in the same manner except that the hard coat composition 1 was changed to the following hard coat composition 2 and the decreasing rate drying zone temperature was changed to 90 ° C.

[Hard coat layer composition 2]
Trimethylolpropane triacrylate (Light acrylate TMP-A, manufactured by Kyoeisha Chemical Co., Ltd.) 80 parts by mass 4-hydroxybutyl acrylate (4-HBA, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 20 parts by mass Irgacure 184 (BASF Japan ( 5 parts by mass Fluoro-siloxane graft polymer (35% by mass) 2 parts by mass Propylene glycol monomethyl ether 10 parts by mass Methyl acetate 45 parts by mass Methyl ethyl ketone 45 parts by mass <Preparation of hard coat film 5>
In the production of the hard coat film 4, a hard coat film 5 was produced in the same manner except that the temperature of the decreasing rate drying section was changed to 95 ° C.

<Preparation of hard coat film 6>
In the production of the hard coat film 1, the hard coat film 6 was produced in the same manner except that the hard coat composition 1 was changed to the following hard coat composition 3 and the decreasing rate drying zone temperature was changed to 100 ° C.

[Hard coat layer composition 3]
Ethoxylated glycerin triacrylate (NK ester A-GLY-9E, manufactured by Shin-Nakamura Chemical Co., Ltd.) 60 parts by mass Ethoxylated isocyanuric acid triacrylate (NK ester A-9300, manufactured by Shin-Nakamura Chemical Co., Ltd.) 40 masses Part Irgacure 184 (manufactured by BASF Japan Ltd.) 5 parts by mass Fluorine-siloxane graft polymer (35% by mass) 2 parts by mass Propylene glycol monomethyl ether 10 parts by mass Methyl acetate 45 parts by mass Methyl ethyl ketone 45 parts by mass <Preparation of hard coat film 7 >
In the production of the hard coat film 6, a hard coat film 7 was produced in the same manner except that the temperature at which the rate of decrease drying interval was changed to 105 ° C.

<Preparation of hard coat film 8>
In the production of the hard coat film 1, a hard coat film 8 was produced in the same manner except that the hard coat composition 1 was changed to the following hard coat composition 4 and the decreasing rate drying zone temperature was changed to 75 ° C.

[Hard coat layer composition 4]
Ethoxylated pentaerythritol tetraacrylate (NK ester ATM-4E, manufactured by Shin-Nakamura Chemical Co., Ltd.) 100 parts by mass Irgacure 184 (manufactured by BASF Japan Ltd.) 5 parts by mass Fluoro-siloxane graft polymer (35% by mass) 2 parts by mass Part Propylene glycol monomethyl ether 10 parts by mass Methyl acetate 45 parts by mass Methyl ethyl ketone 45 parts by mass <Preparation of hard coat film 9>
In the production of the hard coat film 1, a hard coat film 9 was produced in the same manner except that the hard coat composition 1 was changed to the following hard coat composition 5 and the decreasing rate drying zone temperature was changed to 100 ° C.

[Hard Coat Layer Composition 5]
Dipentaerythritol penta / hexaacrylate (NK ester A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd.) 100 parts by mass Irgacure 184 (manufactured by BASF Japan Ltd.) 5 parts by mass Fluorine-siloxane graft polymer (35% by mass) 2 Part by mass Propylene glycol monomethyl ether 10 parts by mass Methyl acetate 45 parts by mass Methyl ethyl ketone 45 parts by mass In addition, in Table 1, dipentaerythritol penta / hexaacrylate, which is a polyfunctional acrylate, was shown as DPHA.

<Preparation of hard coat film 10>
In the production of the hard coat film 1, the hard coat film 10 was produced in the same manner except that the hard coat composition 1 was changed to the following hard coat composition 6 and the decreasing rate drying zone temperature was changed to 120 ° C.

[Hard Coat Layer Composition 6]
Dipentaerythritol penta / hexaacrylate (DPHA) (NK ester A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd.) 50 parts by mass Pentaerythritol tri / tetraacrylate (PETA) (NK ester A-TMM-3L, Shin-Nakamura Chemical) Industrial Co., Ltd.) 50 parts by mass Irgacure 184 (manufactured by BASF Japan Ltd.) 5 parts by mass Fluorine-siloxane graft polymer (35% by mass) 2 parts by mass Propylene glycol monomethyl ether 10 parts by mass Methyl acetate 45 parts by mass Methyl ethyl ketone 45 parts by mass <Production of hard coat film 11>
In the production of the hard coat film 1, the hard coat film 11 was produced in the same manner except that the hard coat composition 1 was changed to the following hard coat composition 7 and the decreasing rate drying zone temperature was changed to 100 ° C.

[Hard Coat Layer Composition 7]
Ethoxylated pentaerythritol tetraacrylate (NK ester ATM-4E, manufactured by Shin-Nakamura Chemical Co., Ltd.) 50 parts by mass 4-hydroxybutyl acrylate (4-HBA, manufactured by Osaka Organic Chemical Industry Co., Ltd.) 50 parts by mass Irgacure 184 ( 5 parts by mass Fluorine-siloxane graft polymer (35% by mass) 2 parts by mass Propylene glycol monomethyl ether 10 parts by mass Methyl acetate 45 parts by mass Methyl ethyl ketone 45 parts by mass <Preparation of hard coat film 12>
In the production of the hard coat film 1, the hard coat film 12 was produced in the same manner except that the hard coat composition 1 was changed to the following hard coat composition 8 and the decreasing rate drying zone temperature was changed to 100 ° C.

[Hard Coat Layer Composition 8]
Mixture of urethane prepolymer and pentaerythritol tetraacrylate (UA-306H, manufactured by Kyoeisha Chemical Co., Ltd.) 100 parts by mass Irgacure 184 (manufactured by BASF Japan Ltd.) 5 parts by mass Fluorine-siloxane graft polymer (35% by mass) 2 parts by mass Part Propylene glycol monomethyl ether 10 parts by mass Methyl acetate 45 parts by mass Methyl ethyl ketone 45 parts by mass <Preparation of hard coat film 13>
In the production of the hard coat film 1, the hard coat film 13 was produced in the same manner except that the hard coat composition 1 was changed to the following hard coat composition 9 and the decreasing rate drying zone temperature was changed to 100 ° C.

[Hard Coat Layer Composition 9]
Adekaoptomer HCX-500-28 100 parts by mass (manufactured by ADEKA Corporation)
Fluorine-siloxane graft polymer (35% by mass) 2 parts by mass <Preparation of hard coat film 14>
In the production of the hard coat film 1, the hard coat film 14 was produced in the same manner except that the hard coat composition 1 was changed to the following hard coat composition 10 and the decreasing rate drying zone temperature was changed to 125 ° C.

[Hard Coat Layer Composition 10]
Dipentaerythritol penta / hexaacrylate (DPHA) (NK ester A-DPH, manufactured by Shin-Nakamura Chemical Co., Ltd.) 10 parts by weight Pentaerythritol tri / tetraacrylate (PETA) (NK ester A-TMM-3L, Shin-Nakamura Chemical) 90 parts by mass Irgacure 184 (manufactured by BASF Japan Ltd.) 5 parts by mass Fluorine-siloxane graft polymer (35% by mass) 2 parts by mass Propylene glycol monomethyl ether 10 parts by mass Methyl acetate 45 parts by mass Methyl ethyl ketone 45 parts by mass Part 《Evaluation》
The following evaluation was performed about the produced said hard coat films 1-14.

(Hard coat film)
a. Measurement of Arithmetic Average Roughness Ra and Average Length RSm of Contour Curve Element Using the optical interference type surface roughness meter (RST / PLUS, manufactured by WYKO) 10 It measured twice and calculated | required arithmetic mean roughness Ra of each hard-coat film and the average length RSm of a contour curve element from the average of the measurement result.

  The obtained results are shown in Table 1.

b. Haze measurement The haze (Hf) of the base film was measured according to JIS-K7136 using a haze meter (NDH2000; manufactured by Nippon Denshoku Industries Co., Ltd.). Next, the haze of each of the hard coat films (Hh) produced above was measured in the same manner as the base film.

  The difference in haze value (Hf) of the base film was subtracted from the haze value (Hh) of each hard coat film, and the absolute value (| Hh−Hf |) of the haze change before and after the hard coat layer application was measured. Table 1 shows the results of haze value (Hh) and haze change (| Hh-Hf |) of the hard coat film.

  In addition, the haze value (Hf) of the base film was 0.28%.

c. Durability test After storing hard coat films 1-14 at 90 ° C and 95% for 200 hours, after putting them in a cycle thermo (at -40 ° C for 30 minutes, then at 85 ° C for 30 minutes alternately, 500 cycles) The sample was irradiated with light for 120 hours using a weather resistance tester (eye super UV tester, manufactured by Iwasaki Electric Co., Ltd.).

d. Evaluation of adhesion after durability On the surface of the hard coat layer of the hard coat film subjected to the above durability test, 11 razor blades were cut at an angle of 90 ° with respect to the surface at an interval of 1 mm vertically and horizontally, and 1 mm square 100 grids were produced. A commercially available cellophane tape is affixed on this, holding one end by hand and pulling it forcefully vertically, and visually observing the ratio of the area where the thin film was peeled off to the tape area affixed from the score line, Evaluation was made according to the following criteria.

A: not peeled at all O: peeled area ratio was less than 10% ×: peeled area ratio was 10% or more

  As can be seen from the results of Table 1, both the arithmetic average roughness Ra of the hard coat layer and the ratio of Ra to the average length RSm of the contour curve element (Ra / RSm) have the scope of the present invention. Is excellent in adhesion when stored in a cycle thermo test and light resistance test after storage at high temperature and high humidity. Moreover, it turns out that the hard coat film of this invention whose arithmetic mean roughness Ra of a hard-coat layer is 4-20 nm has the especially outstanding adhesiveness.

  In addition, the hard coat film of this invention controls the arithmetic mean roughness Ra of a hard-coat layer in the range of this invention by controlling the temperature of the rate-of-decreasing drying area in the drying process after application | coating to 70 to 130 degreeC. This is preferable because it is possible. Moreover, the absolute value (| Hh-Hf |) of the haze change of the hard coat film of the present invention was 0.01% to 0.07%.

  In addition, for the hard coat film according to the present invention, after conditioning at 23 ° C. and 55% RH for 24 hours, using a test pencil specified by JIS-S6006, according to the pencil hardness evaluation method specified by JIS-K5400, 500 g The pencil hardness was tested using a weight. The pencil hardness of the hard coat film according to the present invention was 3H or more.

Example 2
In preparation of the hard coat film 1, the cellulose triacetate of the base film 1 and the ester compound 1 were changed as described in Table 2 to prepare base films 2 and 3. Next, hard coat films 15 and 16 were produced in the same manner except that the hard coat layer 1 was provided on these substrates.

<Evaluation>
In the durability test of Example 1, the durability of the hard coat film 1 produced in Example 1 and the hard coat films 15 and 16 produced in the same manner except that the light irradiation time of the weather resistance test was changed to 240 hours. A property test was conducted and evaluated in the same manner as in Example 1.

  The base films 2 and 3 had a haze value (Hf) of 0.28%.

  Further, tan δ in the film width direction of the base films 1 to 3 was measured by the following method. These results are shown in Table 2.

  In addition, cellulose triacetate B1 shown in Table 2 has an acetyl substitution degree of 2.85 and a number average molecular weight of 120,000. The ester compound B is a compound synthesized by the following method.

<Synthesis of ester compound B>
251 g of 1,2-propylene glycol, 370 g of adipic acid, 122 g of benzoic acid, 0.09 g of tetraisopropyl titanate as an esterification catalyst were charged into a 2 L four-necked flask equipped with a thermometer, a stirrer, and a quick cooling tube, and nitrogen was added. The temperature is gradually raised with stirring until it reaches 230 ° C. in an air stream. The ester compound B was obtained by making it dehydrate-condense for 15 hours and distilling unreacted 1, 2- propylene glycol under reduced pressure at 200 degreeC after completion | finish of reaction. The acid value was 0.55 and the number average molecular weight was 500.

(Measurement of tan δ in the width direction of the base film)
The dynamic viscoelasticity of the base film was measured under the following conditions to determine tan δ ₋₄₀ / tan δ _peak . The sample used was conditioned at 23 ° C. and 55% RH for 24 hours in advance, and the humidity was 55% RH and the temperature was raised under the following conditions, or the temperature was set and measured.

Measuring device: RSA III manufactured by TI Instruments
Sample: width 5 mm, length 50 mm (gap set to 20 mm)
Measurement conditions: Tensile mode Measurement temperature: 25-210 ° C or -40 ° C
Temperature rising condition: 5 ° C / min
Frequency: 1Hz

As can be seen from the results in Table 2, in a severe test, by using a base film having a tan δ in the width direction of 0.5 ≧ tan δ ₋₄₀ / tan δ _peak ≧ 0.24 as a hard coat film, It can be seen that it has excellent adhesion and clearness.

Example 3
<Preparation of Polarizing Plate 101>
(Alkaline saponification treatment)
The hard coat film 1 was attached to one surface of the polarizing film 3 and the protective film 4 made of the cellulose triacetate film 1 was attached to the other surface of the polarizing film 3 to produce a polarizing plate 101 (see FIGS. 2 and 3). ).

(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 processed in the order of preliminary swelling, dyeing, uniaxial stretching by a wet method, fixing treatment, drying, and heat treatment to prepare 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 According to the following steps 1 to 4, the polarizing film 3, the protective film 4, and the hard coat film 1 were bonded together to produce the polarizing plate 101.

  Process 1: The above-mentioned polarizing film 3 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 and the protective film 4 which affixed the peelable protective film (product made from PET) on the hard-coat layer on the following conditions. Next, the excess adhesive adhered to the polarizing film 3 immersed in the polyvinyl alcohol adhesive solution in Step 1 is gently removed, and the polarizing film 3 is sandwiched between the hard coat film 1 and the protective film 4 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.

<Preparation of polarizing plates 102 to 114>
Polarizers 102 to 114 were produced in the same manner except that the hard coat film 1 was changed to the hard coat films 2 to 14 in the production of the polarizer 101.

<Production of Liquid Crystal Display Device 401>
The polarizing plate of the NEC notebook PC LaVie G type liquid crystal panel is peeled off, and the polarizing plate 101 prepared above as a polarizing plate on the viewing side (see FIG. 2 for the configuration and shown as the polarizing plate 7 in FIG. 2) is hard. The peelable protective film of the pressure-sensitive adhesive layer 5 was peeled off so that the coat layer was on the viewing side, and then bonded to the liquid crystal cell glass. 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 414>
Liquid crystal display devices 402 to 414 were similarly manufactured except that the polarizing plate 101 was changed to the polarizing plates 102 to 114 in the preparation of the liquid crystal display device 401.

<Evaluation>
The following evaluation was performed about the produced polarizing plates 101-114 and the image display apparatuses 401-414.

(Polarizer)
a. Durability test After peeling off the peelable protective film of the hard coat layers of the polarizing plates 101 to 114, 75 polarizing plates were stacked on each other as shown in FIG. The film was bonded to the top and stored at 90 ° C. and 95% for 200 hours.

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.

◎: Deformation failure is not seen at all ○: Deformation failure is observed in a small part, but there is no problem in actuality ×: Partial deformation failure is clearly seen even from a distance.

(Liquid crystal display device)
a. Visibility (clearness) evaluation About the produced liquid crystal display devices 401-414, it arrange | positioned on the desk of the height of 80 cm from a floor. Next, a set of 40W x 2 daylight straight tube fluorescent lamps (FLR40S • D / MX Panasonic Corporation) on the ceiling 3m high from the floor, 10 sets at 1.5m intervals Arranged. 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 414 was evaluated according to the following criteria. The obtained results are shown in Table 3.

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

c. Comprehensive evaluation The following criteria evaluated the coexistence of the deformation failure of a polarizing plate and the visibility (clearness) of a liquid crystal display device, and the results are shown in Table 3.

◎: Deformation failure of polarizing plate and visibility of liquid crystal display device ◎
○: Either the deformation failure of the polarizing plate or the visibility of the liquid crystal display device ○
×: Either deformation failure of the polarizing plate or visibility of the liquid crystal display device ×

  As can be seen from the results in Table 3, the polarizing plate and the liquid crystal display device of the present invention composed of the hard coat film of the present invention are resistant to deformation failure when stored under high temperature and high humidity and when used in a liquid crystal display device. It can be seen that it has excellent visibility (clearness) and excellent performance that is compatible with prevention of deformation failure and visibility.

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 (9)

A hard coat film having a hard coat layer on a base film, wherein the arithmetic average roughness Ra of the hard coat layer is in the range of 2 to 20 nm, and the arithmetic average roughness Ra and the average of the contour curve elements The ratio (Ra / RSm) with length RSm exists in the range of 5 * 10 < ^-5 > ^-3 * 10 < ^-4 >, The hard coat film characterized by the above-mentioned.   2. The hard coat film according to claim 1, wherein an arithmetic average roughness Ra of the hard coat layer is in a range of 4 to 20 nm.   The hard coat film according to claim 1, wherein the hard coat layer contains substantially no fine particles.   The hard coat film according to any one of claims 1 to 3, wherein the hard coat layer has protrusions, and the shape of the protrusions is irregular.   The absolute value | Hh−Hf | of the difference between the haze value (Hh) of the hard coat film and the haze value (Hf) of the base film is in the range of 0.0 to 0.8%. The hard coat film according to any one of claims 1 to 4.   The hard coat layer contains an actinic radiation curable resin, and the viscosity of the actinic radiation curable resin is in a range of 30 to 3000 mPa · s. The hard coat film according to any one of the above. The hard coat film according to any one of claims 1 to 6, wherein tan δ in the film width direction of the base film satisfies the following relational expression.
Relational expression: 0.5 ≧ tan δ ₋₄₀ / tan δ _peak ≧ 0.24
Here, tan δ _peak represents the maximum value of tan δ values measured in the range of 25 to 210 ° C., and tan δ ₋₄₀ represents the value of tan δ at a temperature of −40 ° C. when tan δ _peak is indicated.   A polarizing plate comprising the hard coat film according to any one of claims 1 to 7.   A liquid crystal display device comprising the hard coat film according to any one of claims 1 to 7.