JP2007140229A - Hard coat film, polarizing plate and liquid crystal display apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a hard coat film in which thickness unevenness is suppressed by forming a hard coat layer so as to be thin, which has sufficient surface hardness and can be simply molded and further to provide a polarizing plate having the hard coat film and a liquid crystal display apparatus having the polarizing plate. <P>SOLUTION: The hard coat film 1 has the hard coat layer 20 which is laminated on one surface of a base material film 10 and a low refractive index layer 30 which is laminated on a surface of the hard coat layer 20. The base material film 10 is a three-layered laminated body having an uppermost layer A on which the hard coat layer 20 is laminated, an adhesive layer 40 and a thermoplastic resin layer B in this order. Pencil hardness of the uppermost layer A is H or more and a value obtained by multiplication of modulus of tensile elasticity of the uppermost layer A by cube of thickness is 100 kPa×mm<SP>3</SP>or more. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a hard coat film, a polarizing plate, and a liquid crystal display device, and in particular, a hard coat layer that can be formed thin, uneven thickness thereof can be suppressed, has sufficient surface hardness, and can be easily molded. The present invention relates to a coat film, a polarizing plate having the hard coat film, and a liquid crystal display device having the polarizing plate.

  In recent years, for example, plastic members are frequently used in place of glass members for optical members and the like from the viewpoints of lightness and thickness reduction. However, the plastic member has a drawback that the surface is easily damaged. For this reason, for the purpose of imparting scratch resistance, a hard coat film having a hard coat layer on a plastic base film may be provided on the plastic member.

  The hard coat layer constituting the hard coat film is formed, for example, by applying a composition containing an ultraviolet curable resin or the like on a plastic base film and then curing the composition by irradiating with ultraviolet rays. Formed. However, in recent years, there are cases where even higher scratch resistance is required, and in this case, the thin hard coat layer cannot provide sufficient surface hardness.

  Therefore, increasing the thickness of the hard coat layer to improve the surface hardness has been performed. However, in this case, there are problems that the hard coat layer is easily cracked and peeled off from the base film, and that the hard coat film is curled due to curing shrinkage of the hard coat layer. Further, when the thickness of the hard coat layer increases, the thickness unevenness tends to increase. For example, when a hard coat film is used as a protective film for the display surface, there is a problem in that the display quality deteriorates due to the thickness unevenness. It was.

  Therefore, Patent Document 1 discloses a hard coat film in which a buffer layer having a thickness of 3 to 50 μm is provided on at least one surface of a plastic base film, and a hard coat layer having a thickness of 3 to 15 μm is formed on the buffer layer. And the thing whose pencil hardness becomes large in order of a base film, a buffer layer, and a hard-coat layer, and the pencil hardness of the whole hard-coat film is 4H-8H is disclosed.

Further, Patent Document 2, a hard coat layer laminated on the base film, the cube of the product of the surface elastic modulus and the hard coat layer thickness of the hard coat layer is at 30kPa ^· mm ³ ~700kPa ^· mm 3 A hard coat film is disclosed.

JP-A-11-300873 International publication pamphlet WO2003 / 026881

  However, in the hard coat film shown in Patent Document 1, only the ionizing radiation curable resin is used as the buffer layer, and there is a problem that the formation of the hard coat film is complicated. Moreover, in the hard coat film shown in Patent Document 2, the thickness of the hard coat layer is as thick as 30 μm or 45 μm, and there is a problem that the hard coat layer is uneven in thickness, cracked, peeled off, and the hard coat film is easily curled. there were.

  The object of the present invention is to form a hard coat layer thinly, thickness unevenness, cracking, peeling, curling of the hard coat film, having a sufficient surface hardness, and capable of being easily molded, It is providing the polarizing plate which has this hard coat film, and the liquid crystal display device which has this polarizing plate.

According to this invention, the hard coat film shown to (1)-(9) is provided.
(1) A hard coat film having a base film and a hard coat layer laminated on one surface of the base film, wherein the base film has a plurality of layers made of a thermoplastic resin. Of the plurality of layers constituting the laminate, the outermost layer that is in contact with the hard coat layer has a pencil hardness of H or higher, and the tensile modulus of elasticity is the cube of the thickness. A hard-coated film having a multiplied value of 100 kPa · mm ³ or more.

(2) Among the plurality of layers constituting the laminate, at least one of the layers other than the outermost layer has a breaking elongation of 50% or more, and the thickness of the base film is 100 μm or less. The hard coat film as described above.

(3) The hard coat film, wherein the hard coat layer has a thickness of 5 μm or less.

(4) The hard coat film having a humidity expansion coefficient of 30 ppm / K or less.

(5) The hard coat film having a water vapor transmission rate of 100 g / m ² · day or less.

(6) The hard coat film, wherein the base film is formed by a coextrusion method.

(7) The hard coat film, wherein an antireflection layer is further laminated on the hard coat layer.

Moreover, according to the present invention,
(8) A polarizing plate, wherein the other surface of the base film of the hard coat film is laminated on at least one surface of a polarizer,
Is provided.

Moreover, according to the present invention,
(9) A liquid crystal display device having a light source, an incident side polarizing plate, a liquid crystal cell, and an output side polarizing plate in this order, wherein the incident side polarizing plate and / or the output side polarizing plate are the polarizing plates. A liquid crystal display device,
(10) A liquid crystal display device having a light source, an incident side polarizing plate, a liquid crystal cell, and an outgoing side polarizing plate in this order, wherein the outgoing side polarizing plate is the polarizing plate. apparatus,
Is provided.

  According to the hard coat film of the present invention, even if the hard coat layer is formed thin, it has sufficient surface hardness and can be easily formed. Thus, since the hard coat layer can be formed thinly, uneven thickness of the hard coat layer, cracking, peeling from the base film, and curling of the hard coat film can be suppressed. For this reason, this hard coat film can be suitably used as a surface protective film for a display such as a flat panel display (FPD) or a cathode ray tube display (CRT). According to such a display, high scratch resistance can be imparted to the display surface, and deterioration in display quality due to uneven thickness can be prevented.

  The flat panel display (FPD) includes a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), an electroluminescence display (ELD), and the like. Among these, the hard coat film of the present invention can be suitably used as a protective film for a polarizing plate that becomes the surface of an LCD.

  The hard coat film of the present invention comprises a base film and a hard coat layer laminated on one surface of the base film.

<Base film>
A base film is a laminated body which has two or more layers which consist of thermoplastic resins, for example, can be made into a laminated body of 2 layers, or a laminated body of 3 layers or more. Thus, since each layer which comprises a base film was each comprised with the thermoplastic resin, shaping | molding is simple compared with the case where it comprises with curable resin.

In the laminate, the thermoplastic resin constituting the outermost layer which is the layer closest to the hard coat layer has a pencil hardness of H or more, and a value obtained by multiplying the tensile modulus by the cube of the thickness ( Tensile modulus × (thickness cube)) is 100 kPa · mm ³ or more. The value obtained by multiplying the tensile modulus by the cube of the thickness is a scale indicating the rigidity of the layer. By making the structure of the outermost layer as described above, the surface hardness and rigidity of the base film can be sufficiently secured, so that the surface hardness of the entire hard coat film is sufficient even if the thickness of the hard coat layer is reduced. Can be large. Therefore, the hard coat layer can be formed thin to suppress the thickness unevenness and provide sufficient hardness.

  The pencil hardness is a value obtained by a pencil hardness test according to JIS K5600-5-4, and represents the hardness of the object to be measured. In this pencil hardness test, a single layer film made of a thermoplastic resin constituting the outermost layer and having a thickness of 500 μm or more is separately prepared, and the surface of the single layer film is inclined at an angle of 45 degrees from the top of 750 g. It is carried out by checking the degree of scratching by scratching about 5 mm with a pencil with a load of.

  The thermoplastic resin constituting the outermost layer preferably has a light transmittance in the visible region of 400 to 700 nm of 80% or more, more preferably 85% or more when molded to a thickness of 1 mm. % Or more is more preferable. As such a thermoplastic resin, an amorphous resin is preferable from the viewpoint of transparency. In addition, the thermoplastic resin preferably has a glass transition temperature of 60 to 200 ° C, more preferably 90 to 180 ° C. The glass transition temperature can be measured by differential scanning calorimetry (DSC).

  As a thermoplastic resin which comprises the said outermost layer, polymethacrylate resin is preferable and polymethylmethacrylate resin is more preferable. The thickness of the outermost layer is preferably 10 μm or more, more preferably 20 to 60 μm.

  The thermoplastic resin constituting the outermost layer includes colorants such as pigments and dyes, fluorescent brighteners, dispersants, thermal stabilizers, light stabilizers, ultraviolet absorbers, antistatic agents, antioxidants, lubricants, In addition, a material in which a compounding agent such as a solvent is appropriately blended can be used.

  In the laminate, as the thermoplastic resin constituting each layer other than the outermost layer, for example, polycarbonate resin, polyether sulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polyarylate resin, polyethylene Resins, polystyrene resins, polyvinyl chloride resins, cellulose diacetate, cellulose triacetate, and alicyclic olefin polymers can be used.

  Examples of the alicyclic olefin polymer include cyclic olefin random multicomponent copolymers described in JP-A No. 05-310845, US Pat. No. 5,179,171, JP-A No. 05-97978, and US Pat. No. 5,202,388. Examples thereof include the hydrogenated polymers described, thermoplastic dicyclopentadiene ring-opening polymers described in JP-A No. 11-124429 (WO 99/20676), and hydrogenated products thereof.

  The thermoplastic resin constituting each layer other than the outermost layer preferably has a light transmittance in the visible region of 400 to 700 nm of 80% or more, more preferably 85% or more when molded to a thickness of 1 mm. 90% or more is more preferable. The thermoplastic resin is preferably an amorphous resin from the viewpoint of transparency. In addition, the thermoplastic resin preferably has a glass transition temperature of 60 to 200 ° C, more preferably 90 to 180 ° C. Moreover, the said compounding agent is mix | blended with the thermoplastic resin which comprises each layer as needed.

  The thermoplastic resin constituting at least one of the layers other than the outermost layer preferably has a breaking elongation of 50% or more, more preferably 100% or more. The total thickness is preferably 100 μm or less. By providing at least one layer having the above elongation at break while keeping the thickness of the base film within the above range, sufficient flexibility can be imparted to the base film while maintaining the hardness of the base film.

  The elongation at break of the thermoplastic resin is measured by a tensile fracture strain test described in JIS K7161. As the thermoplastic resin satisfying such conditions, polyethylene terephthalate resin, the alicyclic olefin polymer, cellulose triacetate and the like are preferable. The sum total of the thickness of these preferable layers is 5-100 micrometers normally, Preferably it is 10-50 micrometers. The total thickness of such layers is preferably 5% or more, more preferably 10% or more, with respect to the total thickness of the base film.

  The base film as described above is not particularly limited depending on the production method. Examples of the method for producing the base film include a method in which single-layer thermoplastic resin films are bonded together, a method in which a plurality of thermoplastic resins are coextruded (coextrusion method), and a thermoplastic resin solution is cast on the thermoplastic resin film. Or the like. Among these, from the viewpoint of productivity and the like, the coextrusion method is preferable as the method for producing the base film. In this case, since it is not necessary to go through a complicated process (for example, a drying process or a coating process), there is an advantage that a hard coat film excellent in optical characteristics can be provided with little mixing of external foreign matters such as dust. .

  Here, each layer which comprises a laminated body may be in contact directly, and may be in contact through the contact bonding layer. This adhesive layer includes the concept of an adhesive layer. Here, when each layer is in direct contact, different types of thermoplastic resins are used for the respective layers. In the laminate of three or more layers, different types of thermoplastic resins are used for the layers that are in direct contact, but the same types of thermoplastic resins may be used for the layers that are not in direct contact. Moreover, when each layer contacts indirectly through an adhesive layer or an adhesive layer, the same kind of thermoplastic resin may be used for each layer.

  As said adhesive layer, the average thickness is 0.01-30 micrometers normally, Preferably it is 0.1-10 micrometers. Adhesives constituting the adhesive layer include acrylic adhesive, urethane adhesive, polyester adhesive, polyvinyl alcohol adhesive, polyolefin adhesive, modified polyolefin adhesive, polyvinyl alkyl ether adhesive, rubber adhesive, vinyl chloride / acetic acid Vinyl adhesive, styrene / butadiene / styrene copolymer (SBS copolymer) adhesive, hydrogenated product (SEBS copolymer) adhesive, ethylene / vinyl acetate copolymer, ethylene-styrene copolymer, etc. Examples include ethylene adhesives, ethylene / methyl methacrylate copolymers, ethylene / methyl acrylate copolymers, ethylene / ethyl methacrylate copolymers, and acrylic ester adhesives such as ethylene / ethyl acrylate copolymers. be able to.

<Hard coat layer>
The hard coat layer is a high hardness layer having a hardness of “4H” or higher in a pencil hardness test (a glass plate is used as a test plate) shown in JIS K5600-5-4, and is formed from a curable material. It is preferable. Examples of the material for forming the hard coat layer include organic hard coat materials such as organic silicone, melamine, epoxy, acrylic, and urethane acrylate; and inorganic hard coat materials such as silicon dioxide. Among these, the use of urethane acrylate-based and polyfunctional acrylate-based hard coat materials is preferable from the viewpoint of good adhesion and excellent productivity.

  The hard coat material was blended with various fillers for the purpose of adjusting the refractive index, improving the flexural modulus, stabilizing the volume shrinkage, improving heat resistance, antistatic properties, antiglare properties, etc., as desired. Things can be used. Furthermore, as the hard coat material, a material containing various additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a leveling agent, and an antifoaming agent can be used.

  Examples of the filler include titanium oxide, zirconium oxide, zinc oxide, tin oxide, cerium oxide, antimony pentoxide, tin-doped indium oxide (ITO), antimony-doped tin oxide (IZO), and aluminum-doped zinc oxide. (AZO), fluorine-doped tin oxide (FTO), and the like. In view of maintaining transparency, the filler is preferably antimony pentoxide, ITO, IZO, ATO, or FTO. The primary particle diameter of the filler is usually 1 nm to 100 nm, preferably 1 nm to 30 nm. The primary particle size of the filler may be measured visually from an image photograph obtained by a scanning microscope (SEM) or the like, or measured by a particle size distribution meter using a dynamic light scattering method or a static light scattering method. May be.

  The filler for imparting antiglare properties preferably has an average particle size of 0.5 to 10 μm, more preferably 1.0 to 7.0 μm, and even more preferably 1.0 to 4.0 μm. Specific examples of fillers that impart antiglare properties include polymethyl methacrylate resins, vinylidene fluoride resins and other fluororesins, silicone resins, epoxy resins, nylon resins, polystyrene resins, phenol resins, polyurethane resins, crosslinked acrylic resins, Fillers made of organic resins such as cross-linked polystyrene resin, melamine resin, and benzoguanamine resin; such as titanium oxide, aluminum oxide, indium oxide, zinc oxide, antimony oxide, tin oxide, zirconium oxide, ITO, magnesium fluoride, and silicon oxide The filler which consists of an inorganic compound is mentioned.

  Moreover, it is preferable that the thickness of a hard-coat layer is 5 micrometers or less. By setting the thickness in such a range, it is possible to prevent the hard coat layer from cracking and peeling from the base film, and the hard coat layer curl due to curing shrinkage. For this reason, the hard coat film which has such a hard coat layer is suitable for an optical member use.

  The method for forming the hard coat layer is not particularly limited. The hard coat layer is, for example, coated with a solution of an active energy ray curable resin, which is one of the forming materials, on the outermost layer of the base film by a known coating method, and irradiated with active energy rays such as ultraviolet rays. It can be formed by curing.

<Other layers>
When using the hard coat film of this invention for the display screen of a display, for example, it is preferable that the antireflection layer is further laminated | stacked on the hard coat layer. The antireflection layer is a layer for preventing the transfer of external light. The hard coat film on which such an antireflection layer is laminated has an incident angle of 5 °, a reflectance at 430 to 700 nm of 2.0% or less, and a reflectance at 550 nm of 1.0% or less. preferable. The thickness of the antireflection layer is preferably 0.01 μm to 1 μm, and more preferably 0.02 μm to 0.5 μm. As such an antireflection layer, for example, a low refractive index layer having a refractive index smaller than that of the hard coat layer, preferably a refractive index of 1.30 to 1.45, or a low refractive index composed of an inorganic compound. Examples thereof include those obtained by repeatedly laminating a refractive index layer and a high refractive index layer made of an inorganic compound.

  As the low refractive index layer, a layer formed of a material having a minute air layer (bubbles) can be used. The thickness of the low refractive index layer is usually 10 to 1000 nm, preferably 30 to 500 nm. Examples of the material having a minute air layer include airgel. The airgel is a transparent porous body in which minute bubbles are dispersed in a matrix. Most of the size of the bubbles is 200 nm or less, and the content of the bubbles is usually 10 to 60% by volume, preferably 20 to 40% by volume. Examples of the airgel include silica aerogel and a porous body in which hollow particles are dispersed in a matrix.

  Silica aerogel is a gel-like substance composed of a silica skeleton obtained by hydrolysis polymerization reaction of alkoxysilane, as disclosed in U.S. Pat. No. 4,402,927, U.S. Pat. No. 4,432,956, U.S. Pat. The compound can be prepared by wetting with a solvent (dispersion medium) such as alcohol or carbon dioxide and removing the solvent by supercritical drying. Silica airgel can be produced in the same manner as described above using sodium silicate as a raw material, as disclosed in US Pat. No. 5,137,279, US Pat. No. 5,124,364, and the like.

  In the present invention, as disclosed in JP-A-5-279011 and JP-A-7-138375 (US Pat. No. 5,496,527), a gel obtained by hydrolysis and polymerization reaction of alkoxysilane. It is preferable to hydrophobize the compound to impart hydrophobicity to the silica airgel. Hydrophobic silica airgel imparted with hydrophobicity is difficult for moisture, water, and the like to enter, and can prevent performance such as refractive index and light transmittance of silica airgel from deteriorating.

  Examples of the porous body in which hollow fine particles are dispersed in a matrix include porous bodies as disclosed in Japanese Patent Application Laid-Open Nos. 2001-233611 and 2003-149642. The porous body in which the hollow fine particles are dispersed in the matrix is not included in the thermoplastic resin layer.

  The material used for the matrix is selected from materials that meet conditions such as dispersibility of hollow fine particles, transparency of the porous body, and strength of the porous body. For example, hydrolyzable organosilicon compounds such as polyester resin, acrylic resin, urethane resin, vinyl chloride resin, epoxy resin, melamine resin, fluorine resin, silicone resin, butyral resin, phenol resin, vinyl acetate resin, alkoxysilane, Examples include decomposed products. Among these, acrylic resin, epoxy resin, urethane resin, silicone resin, hydrolyzable organosilicon compound and hydrolyzate thereof are preferable from the viewpoint of dispersibility of the hollow fine particles and the strength of the porous body.

The hollow fine particles are not particularly limited, but inorganic hollow fine particles are preferable. Examples of the inorganic compound constituting the inorganic hollow fine particles include SiO ₂ , Al ₂ O ₃ , B ₂ O ₃ , TiO ₂ , ZrO ₂ , SnO ₂ , Ce ₂ O ₃ , P ₂ O ₅ , Sb ₂ O ₃ , MoO _{3. , ZnO 2, WO 3, TiO} 2 -Al 2 O 3, TiO 2 -ZrO 2, In 2 O 3 -SnO 2, Sb 2 O 3 -SnO 2 or the like can be exemplified. In addition, said "-" shows that it is complex oxide. Among these, silica-based hollow fine particles are particularly preferable.

  The outer shell of the hollow fine particles may be porous having pores, and at this time, the fine pores of the hollow fine particles may be closed on the outside. In the cavities and pores that are hollow portions of the hollow particles, there may be a solvent used when preparing the hollow fine particles and / or a gas that enters during drying, and a precursor material for forming the cavities is present. It may remain.

  The average particle size of the hollow fine particles is not particularly limited, but is preferably in the range of 5 to 2,000 nm, more preferably 20 to 100 nm. Here, the average particle diameter is a number average particle diameter by observation with a transmission electron microscope.

  In the hard coat film of the present invention, an antifouling layer may be further provided on the low refractive index layer in order to enhance the antifouling property of the low refractive index layer. The antifouling layer is a layer that can impart water repellency, oil repellency, sweat resistance, antifouling property, etc. to the surface of the protective film for polarizing plate. As a material used for forming the antifouling layer, a fluorine-containing organic compound is suitable. Examples of the fluorine-containing organic compound include fluorocarbon, perfluorosilane, or a polymer compound thereof.

<Hard coat film>
The hard coat film of the present invention preferably has a humidity expansion coefficient of 30 ppm /% RH or less. The humidity expansion coefficient can be calculated by measuring the linear expansion of the film accompanying changes in humidity. When the humidity expansion coefficient is within the above range, deformation of the hard coat film due to humidity can be prevented, and in this case, the hard coat film can be suitably used for an optical member such as a polarizing plate. Moreover, it is preferable that a temperature expansion coefficient is 60 ppm / K or less. The temperature expansion coefficient can be measured according to JIS K7140.

Further, the hard coat film of the present invention preferably has a water vapor transmission rate is less than 100g ^/ m 2 · day, more preferably at most 80g ^/ m 2 · day. The water vapor transmission rate of the hard coat film can be measured by the method described in JIS K7129 under the test conditions for 24 hours in an environment of 40 ° C. and 92% RH. When the water vapor transmission rate is in the above range, particularly when the hard coat film is used as a protective film for a polarizing plate, deterioration of the polarizer constituting the polarizing plate due to moisture can be reduced.

  In the hard coat film of the present invention, the pencil hardness of the hard coat layer side surface measured with a ready-made hard coat film is preferably 4H or more. In this case, the hard coat film has improved scratch resistance and has a sufficient surface protection function.

  The hard coat film of the present invention preferably has a flexibility defined by JIS K5600-5-1 of 4 mm or less. In this case, since sufficient flexibility is imparted to the film, even if stress is applied to the hard coat film, it is possible to prevent the hard coat film from being cracked or deformed.

<Use of hard coat film>
The hard coat film as described above can be suitably used as a surface protective film for a display such as a flat panel display (FPD) and a cathode ray tube display (CRT). The FPD includes a liquid crystal display (LCD), a plasma display panel (PDP), a field emission display (FED), an electroluminescence display (ELD), and the like. Among these, this hard coat film can be suitably used as a protective film for a polarizing plate that becomes the surface of a liquid crystal display device.

<Polarizing plate>
The polarizing plate of the present invention comprises a polarizer and the hard coat film in which the surface on the base film side is laminated on at least one surface of the polarizer. With such a configuration, since the hard coat film has sufficient hardness and toughness, the surface of the polarizer can be sufficiently protected, and a polarizing plate having a sufficient degree of polarization can be provided.

  As the polarizer, a known polarizer used for a liquid crystal display device or the like can be used. Examples of the polarizer include those obtained by adsorbing iodine or dichroic dye on a polyvinyl alcohol film and then uniaxially stretching in a boric acid bath, or adsorbing iodine or dichroic dye on a polyvinyl alcohol film. And those obtained by stretching and further modifying a part of the polyvinyl alcohol unit in the molecular chain to a polyvinylene unit. As such a polarizer, the degree of polarization is preferably 98% or more, and more preferably 99% or more.

<Liquid crystal display device>
The liquid crystal display device of the present invention is a liquid crystal display device having a light source, an incident side polarizing plate, a liquid crystal cell, and an outgoing side polarizing plate in this order, and the incident side polarizing plate and / or the outgoing side polarizing plate are It is a polarizing plate. At this time, it is preferable that the polarizing plate is used as an output side polarizing plate. With such a configuration, a liquid crystal display device with excellent display quality can be provided.

  Next, the present invention will be described in more detail using examples and comparative examples. The present invention is not limited to the following examples.

<Test and evaluation method>
(1) Tensile modulus Measured according to JIS K7161.
(2) Pencil hardness It measured by the following method based on JIS K5600-5-4. A pencil core cut into a cylindrical shape is tilted at an angle of 45 degrees, a load of 750 g is applied from above, and the surface of the object to be measured is scratched by about 5 mm to check for scratches.
(3) Elongation at break Measured according to JIS K7161. When the sample failed without yielding, the tensile elongation at break was determined by the measured value of tensile fracture strain, and when fractured after yielding, the nominal strain at tensile fracture was measured.
(4) Flexibility Measured according to JIS K5600-5-1. The largest mandrel diameter that causes cracking and crazing in the sample film is used as an index of flexibility.
(5) Humidity expansion coefficient The humidity expansion coefficient was measured with a precision universal testing machine (Autograph AG-IS, Shimadzu Corporation) equipped with a constant temperature and humidity chamber and an automatic extensometer. B-shaped test pieces were prepared in accordance with JIS K7139, and marked lines were provided at intervals of 50 mm. While maintaining the temperature at 23 ± 0.5 ° C, pulling both ends of the test piece with a load of 10 N, changing the humidity from 30% RH to 70% RH, and the displacement of the marked line interval of 50 mm (ΔL) with an automatic extensometer Was measured. The humidity expansion coefficient (β) was calculated from the measured value by the following formula (A).
β = ΔL / (50 × 40) (A)
(6) Temperature expansion coefficient It was measured according to JIS K7140.
(7) Water vapor transmission rate Measured at a measurement temperature of 40 ° C. according to JIS K7129.
(8) Layer thickness The film cross section was cut with a microtome (ULTRACUT UCT, manufactured by Leica), and the cross section was measured from an image observed with a scanning electron microscope (S-3000N, manufactured by Hitachi, Ltd.).
(9) Light Leakage Test As a test piece, two 10 cm × 10 cm polarizing plates are cut out and left in an environment at a temperature of 80 ° C. and a relative humidity of 90% for 100 hours. Thereafter, the test piece taken out indoors is placed in a crossed Nicol, placed on a light box with a color density of 5000K, and visually observed for light leakage.

<Preparation of hard coating agent>
To 100 parts of methyl isobutyl ketone sol of antimony pentoxide (solid content concentration 40%, manufactured by Catalyst Kasei Co., Ltd.), 8 parts of dipentaerythritol hexaacrylate, 2 parts of trimethylolpropane triacrylate, photoinitiator 2-hydroxy-2-methyl Propiophenone 0.4 part was mixed and the ultraviolet curable hard coat agent H was obtained.

<Preparation of coating solution for forming low refractive index layer>
100 parts of isopropyl alcohol sol of hollow silica fine particles (solid content concentration 20% made by Catalyst Kasei Co., Ltd.), 20 parts of tetramethoxysilane oligomer methyl silicate 511 (made by Colcoat), 34 parts of ammonia water (ammonia 28% by weight), methanol 600 parts of the mixture were mixed to obtain a coating liquid L for forming a low refractive index layer.

<Example>
(Configuration of the entire hard coat film)
A hard coat film 1 according to the present invention was produced according to the following procedure. The configuration of the hard coat film 1 will be described with reference to the drawings. As shown in FIG. 1, the hard coat film 1 includes a base film 10, a hard coat layer 20 laminated on one surface of the base film 10, and a reflection laminated on the hard coat layer 20. And a low refractive index layer 30 as a prevention layer. Hereinafter, the manufacturing procedure of each component 10, 20, 30 will be described in detail.

(Preparation of base film 10)
A polymethyl methacrylate resin (SUMIPEX MH, manufactured by Sumitomo Chemical Co., Ltd .: described as PMMA in Table 1 described later) for forming the outermost layer, and an adhesive layer are configured using a three-layer / three-layer multi-layer coextrusion apparatus. SEBS copolymer adhesive (Tuftec H1041, manufactured by Asahi Kasei Chemicals: listed as SEBS in Table 1), alicyclic olefin polymer (ZEONOR 1020, manufactured by Nippon Zeon Co., Ltd.) for constituting layers other than the outermost layer: In Table 1, COP) is discharged from a T-die at an extrusion rate of 20 kg / hr, 1 kg / hr, and 10 kg / hr, respectively, and this discharge is cooled using a metal roll at 100 ° C. Substrate film in which methacrylate resin layer A (40 μm thickness) -SEBS resin adhesive layer 40 (2 μm thickness) -alicyclic olefin polymer layer B (20 μm thickness) is laminated 10 was obtained by co-extrusion. In the base film 10, the outermost layer is the polymethyl methacrylate resin layer A. The tensile elastic modulus of the polymethyl methacrylate resin layer A is 3300 kPa.

(Preparation of hard coat layer 20)
Next, the hard coat agent H is applied to the surface of the polymethyl methacrylate resin layer A of the obtained base film 10 using a wire bar, dried (100 ° C. × 2 minutes), and irradiated with ultraviolet rays (integrated light quantity 1000 mW / cm). ² ) to obtain a hard coat layer 20 having a thickness of 5 μm.

(Preparation of low refractive index layer 30)
Next, the low refractive index layer coating liquid L is applied onto the hard coat layer 20 using a wire bar and heated (140 ° C. × 10 minutes) to obtain a low refractive index layer 30 having a thickness of 100 nm. It was.
Thus, a hard coat film 1 as shown in FIG. 1 was obtained.

<Comparative Example 1>
The hard coat film 2 was used in the same manner as in Example 1 except that instead of the base film 1, a triacetylcellulose film 11 (KC8UX2M, manufactured by Konica Minolta, thickness 80 μm: expressed as TAC in Table 1) was used. Got. The tensile elastic modulus of the triacetyl cellulose film is 3700 kPa.

<Comparative example 2>
A hard coat film 3 was obtained in the same manner as in Example 1 except that the following base film 12 was used instead of the base film 10.
(Preparation of base film 12)
Polystyrene resin (HF77, manufactured by PS Japan Co., Ltd .: described as PS in Table 1) for constituting the outermost layer using a three-layer / three-layer multi-layer coextrusion apparatus, and SEBS co-weight for constituting the adhesive layer Combined adhesive (Tuftec H1041, manufactured by Asahi Kasei Chemicals) and alicyclic olefin polymer (Zeonor 1020, manufactured by Nippon Zeon Co., Ltd.) for constituting layers other than the outermost layer, 20 kg / hr, 1 kg / hr, 10 kg / It is discharged from a T-type die with an extrusion amount of hr, and the discharged product is cooled using a metal roll at 100 ° C., and a polystyrene resin layer (40 μm thickness) -SEBS resin adhesive layer (2 μm thickness) -alicyclic ring as the outermost layer The base film 12 on which the formula olefin polymer layer (20 μm thick) was laminated was obtained. The tensile elastic modulus of the polystyrene resin layer is 3300 kPa.

<Comparative Example 3>
A hard coat film 4 was obtained in the same manner as in Example 1 except that the following base film 13 was used instead of the base film 10.
(Preparation of base film 13)
Polymethylmethacrylate resin (Sumipex MH, manufactured by Sumitomo Chemical Co., Ltd.) for constituting the outermost layer using a three-layer / three-layer multi-layer coextrusion apparatus, SEBS copolymer adhesive (Tuftec) for constituting the adhesive layer H1041, manufactured by Asahi Kasei Chemicals), and alicyclic olefin polymers (Zeonor 1020, manufactured by Nippon Zeon Co., Ltd.) for constituting layers other than the outermost layer, respectively, at extrusion rates of 15 kg / hr, 1 kg / hr, and 15 kg / hr, respectively. It is discharged from a T-shaped die, and this discharge is cooled using a metal roll at 100 ° C., and a polymethyl methacrylate resin layer (30 μm thickness) -SEBS resin adhesive layer (2 μm thickness) -alicyclic olefin polymer layer (30 μm thickness) ) Was obtained.

<Result>
The evaluation mentioned above was performed about each hard coat film 1-4 obtained as mentioned above. The results are shown in Table 1.

  As shown in Table 1, in Example 1, it can be seen that the pencil hardness of the surface of the hard coat film 1 is as high as 5H or more, and the surface has excellent scratch resistance. Furthermore, in Example 1, since the flexibility is 4 mm, it can be seen that the hard coat film 1 has sufficient toughness and is not easily cracked. On the other hand, in Comparative Examples 1 to 3, the pencil hardness of the hard coat film surface is as low as HB to 2H, which indicates that the scratch resistance of the surface is insufficient.

Moreover, the polarizing plate was produced using the said hard coat films 1-4.
A 75 μm-thick polyvinyl alcohol film (Kuraray Vinylon # 7500, manufactured by Kuraray Co., Ltd.) is attached to the chuck, and immersed in an aqueous solution at 30 ° C. containing 0.2 g / L of iodine and 60 g / L of potassium iodide, 6.0 times Then, boric acid treatment was performed for 5 minutes. Finally, it was dried at room temperature for 24 hours to obtain a polarizer.

  Next, the surface opposite to the hard coat layer of each of the hard coat films 1 to 4 is bonded to one side of the polarizer via an acrylic adhesive (DP-8005 clear, manufactured by Sumitomo 3M), and the polarizer. On the other side, a 40 μm-thick norbornene resin (Zeonor 1410R, manufactured by Nippon Zeon Co., Ltd.) was attached via the same acrylic adhesive to produce a polarizing plate.

  As shown in Table 1, it was found from the results of the light leakage test that Example 1 was excellent in temperature and humidity durability, and Comparative Example 1 was inferior in temperature and humidity durability.

  Furthermore, a liquid crystal display device in which the obtained polarizing plate was applied as an output-side polarizing plate was produced. As a result, as shown in Table 1, it was found that any liquid crystal display device can maintain a satisfactory display quality.

  In summary, according to the hard coat film shown in Example 1, even a hard coat layer as relatively thin as 5 μm has sufficient surface scratch resistance and is used as a protective film for a polarizing plate of a liquid crystal display device. It was found that the display performance was sufficient.

It is sectional drawing which shows typically the structure of the hard coat film which concerns on the Example of this invention.

Explanation of symbols

1 Hard Coat Film 10 Base Film 20 Hard Coat Layer 30 Low Refractive Index Layer (Antireflection Layer)
40 Adhesive layer A Thermoplastic resin layer (outermost layer)
B Thermoplastic resin layer (layers other than the outermost layer)

Claims (10)

A hard coat film having a base film and a hard coat layer laminated on one surface of the base film,
The base film is a laminate having a plurality of layers made of a thermoplastic resin,
Of the plurality of layers constituting the laminate, the outermost layer, which is the closest layer to the hard coat layer, has a pencil hardness of H or higher, and the tensile modulus is multiplied by the cube of the thickness. A hard coat film having a value of 100 kPa · mm ³ or more.   Among the plurality of layers constituting the laminate, at least one of the layers other than the outermost layer has a breaking elongation of 50% or more, and the thickness of the base film is 100 μm or less. The hard coat film according to claim 1.   The hard coat film according to claim 1, wherein the hard coat layer has a thickness of 5 μm or less.   The hard coat film according to any one of claims 1 to 3, wherein a humidity expansion coefficient is 30 ppm /% RH or less. The water vapor transmission rate is 100 g / m ² · day or less, and the hard coat film according to any one of claims 1 to 4.   The hard coat film according to claim 1, wherein the base film is formed by a coextrusion method.   The hard coat film according to claim 1, wherein an antireflection layer is further laminated on the hard coat layer.   A polarizing plate, wherein the other surface of the base film of the hard coat film according to any one of claims 1 to 7 is laminated on at least one surface of a polarizer.   9. The liquid crystal display device having a light source, an incident side polarizing plate, a liquid crystal cell, and an output side polarizing plate in this order, wherein the incident side polarizing plate and / or the output side polarizing plate are polarized light according to claim 8. A liquid crystal display device characterized by being a plate. A liquid crystal display device having a light source, an incident side polarizing plate, a liquid crystal cell, and an outgoing side polarizing plate in this order, wherein the outgoing side polarizing plate is the polarizing plate according to claim 8. Liquid crystal display device.

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