JP2018155809A - Polarizing plate and image display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a polarizing plate that reduces scratches on a surface with a simple configuration.SOLUTION: A polarizing plate comprises: a polarizer; and a protective film arranged on at least one side of the polarizer. The protective film contains an acrylic resin and core-shell type particles dispersed in the acrylic resin, and the arithmetic average roughness Ra of a surface of the protective film is 6.0 μm or more.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a polarizing plate and an image display device.

  In an image display device (for example, a liquid crystal display device or an organic EL display device), a polarizing plate is often disposed on at least one side of a display cell due to the image forming method. A general polarizing plate includes a polarizer and a protective film disposed on one side or both sides of the polarizer. In recent years, it has been proposed to use a protective film made of a (meth) acrylic resin film containing a crosslinked elastic body for the purpose of improving durability (Patent Document 1).

JP, 2006-218478, A

  In recent years, with the demand for thinning of an image display device, it has become necessary to arrange optical members constituting the image display device close to each other. As a result, the protective film of the polarizing plate may be damaged when the polarizing plate comes into contact with an optical member such as a diffusion sheet disposed adjacently. In order to solve such a problem, it has hitherto been proposed to suppress scratches on the protective film by forming a hard coat layer or a diffusion layer on the surface of the polarizing plate. However, these methods may cause a problem that productivity may be reduced due to an increase in the number of manufacturing steps, and costs may be increased.

  The present invention has been made to solve the above-described conventional problems, and a main object thereof is to provide a polarizing plate in which scratches on the surface are suppressed with a simple configuration and an image display device including the polarizing plate. is there.

The polarizing plate of the present invention has a polarizer and a protective film disposed on at least one side of the polarizer, and the protective film is an acrylic resin and a core-shell type dispersed in the acrylic resin. The arithmetic average roughness Ra of the surface of the protective film is 6.0 μm or more.
In one embodiment, the acrylic resin has at least one selected from the group consisting of a glutarimide unit, a lactone ring unit, a maleic anhydride unit, a maleimide unit, and a glutaric anhydride unit.
In one embodiment, the unevenness | corrugation by the said core-shell type particle | grains is formed in the surface on the opposite side to the said polarizer of a protective film.
In one embodiment, the protective film contains 3 to 50 parts by weight of the core-shell type particles with respect to 100 parts by weight of the acrylic resin.
In one embodiment, the core-shell type particle has a core made of a rubber-like polymer and a coating layer made of a glass-like polymer and covering the core.
In one embodiment, the protective film is a biaxially stretched film.
In one embodiment, there is no diffusion layer on the surface of the protective film.
According to another aspect of the present invention, an image display device is provided. The image display device includes a display cell, the polarizing plate, a diffusion sheet, and a light source in this order, and the protective film of the polarizing plate is disposed to face the diffusion sheet.

  ADVANTAGE OF THE INVENTION According to this invention, an image display apparatus provided with the polarizing plate by which the damage | wound of the surface was suppressed by simple structure and the said polarizing plate can be provided.

It is sectional drawing of the polarizing plate by one Embodiment of this invention. It is sectional drawing of the polarizing plate by another embodiment of this invention.

  Hereinafter, although embodiment of this invention is described, this invention is not limited to these embodiment.

A. 1 is a cross-sectional view of a polarizing plate according to one embodiment of the present invention. The polarizing plate 10 includes a polarizer 1 and a protective film 2 disposed on one side of the polarizer 1. The protective film 2 includes an acrylic resin and core-shell type particles dispersed in the acrylic resin. The arithmetic average roughness Ra of the surface of the protective film 2 is 6.0 μm or more. Preferably, unevenness due to the core-shell type particles is formed on the surface of the protective film 2 opposite to the polarizer 1. The protective film 2 preferably contains 3 to 50 parts by weight of core-shell type particles with respect to 100 parts by weight of the acrylic resin. The core-shell type particle typically has a core made of a rubbery polymer and a coating layer made of a glassy polymer and covering the core. The protective film 2 is preferably a biaxially stretched film. In one embodiment, the polarizing plate 10 does not have a diffusion layer on the surface of the protective film 2. The polarizing plate of the present invention can suppress the occurrence of scratches due to friction with the other optical members, even when the polarizing plate is incorporated into an image display device and is in contact with an optical member such as a diffusion sheet.

  FIG. 2 is a cross-sectional view of a polarizing plate according to another embodiment of the present invention. The polarizing plate 11 includes a polarizer 1, a protective film 2 (first protective film) disposed on one side of the polarizer 1, and a second protective film 3 disposed on the other side of the polarizer 1. And have. The second protective film 3 may be a film formed of the same material as the first protective film 2 or may be a film formed of another material. The polarizing plate 11 may have any appropriate optical function film according to the purpose and application instead of the second protective film 3.

  The polarizing plate 10 and the polarizing plate 11 may be a single wafer or may be long. The polarizing plate 10 may have an adhesive layer (not shown) on the surface of the polarizer 1, and the polarizing plate 11 may have an adhesive layer (shown on the surface of the second protective film 3). (Not shown).

B. Polarizer Any appropriate polarizer may be adopted as the polarizer. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

  Specific examples of polarizers composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and ethylene / vinyl acetate copolymer partially saponified films. In addition, there may be mentioned polyene-based oriented films such as those subjected to dyeing treatment and stretching treatment with dichroic substances such as iodine and dichroic dyes, PVA dehydrated products and polyvinyl chloride dehydrochlorinated products. Preferably, a polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching is used because of excellent optical properties.

  The dyeing with iodine is performed, for example, by immersing a PVA film in an iodine aqueous solution. The stretching ratio of the uniaxial stretching is preferably 3 to 7 times. The stretching may be performed after the dyeing treatment or may be performed while dyeing. Moreover, you may dye | stain after extending | stretching. If necessary, the PVA film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment and the like. For example, by immersing the PVA film in water and washing it before dyeing, not only can the surface of the PVA film be cleaned of dirt and anti-blocking agents, but the PVA film can be swollen to cause uneven staining. Can be prevented.

  As a specific example of a polarizer obtained by using a laminate, a laminate of a resin substrate and a PVA resin layer (PVA resin film) laminated on the resin substrate, or a resin substrate and the resin Examples thereof include a polarizer obtained by using a laminate with a PVA resin layer applied and formed on a substrate. For example, a polarizer obtained by using a laminate of a resin base material and a PVA resin layer applied and formed on the resin base material may be obtained by, for example, applying a PVA resin solution to a resin base material and drying it. A PVA-based resin layer is formed thereon to obtain a laminate of a resin base material and a PVA-based resin layer; the laminate is stretched and dyed to make the PVA-based resin layer a polarizer; obtain. In the present embodiment, stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Further, the stretching may further include, if necessary, stretching the laminate in the air at a high temperature (for example, 95 ° C. or higher) before stretching in the boric acid aqueous solution. The obtained resin base material / polarizer laminate may be used as it is (that is, the resin base material may be used as a protective layer of the polarizer), and the resin base material is peeled from the resin base material / polarizer laminate. Any appropriate protective layer according to the purpose may be laminated on the release surface. Details of a method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580. This publication is incorporated herein by reference in its entirety.

  The thickness of the polarizer is, for example, 1 μm to 80 μm. In one embodiment, the thickness of the polarizer is preferably 1 μm to 15 μm, more preferably 3 μm to 10 μm, and particularly preferably 3 μm to 8 μm.

C. Protective film C-1. Properties of Protective Film As described above, the protective film includes an acrylic resin and core-shell type particles dispersed in the acrylic resin, and the arithmetic average roughness Ra of the surface of the protective film is 6.0 μm or more. The arithmetic average roughness Ra is preferably 6 μm to 50 μm, and more preferably 6 μm to 40 μm. By setting the upper limit of the arithmetic average roughness Ra to the above value, it is possible to suppress the slipperiness of the surface of the protective film from becoming too high, and as a result, the winding slip when the protective film (and the polarizing plate) is elongated. Can be suppressed. The arithmetic average roughness Ra can be adjusted within a desired range depending on the content of the core-shell type particles in the protective film, the stretching conditions in the method for producing the protective film described later, and the like. The thickness of the protective film is preferably 5 μm to 150 μm, more preferably 10 μm to 100 μm.

  The protective film is preferably substantially optically isotropic. In this specification, “substantially optically isotropic” means that the in-plane retardation Re (550) is 0 nm to 10 nm and the thickness direction retardation Rth (550) is −10 nm to +10 nm. Say something. The in-plane retardation Re (550) is more preferably 0 nm to 5 nm, still more preferably 0 nm to 3 nm, and particularly preferably 0 nm to 2 nm. The thickness direction retardation Rth (550) is more preferably −5 nm to +5 nm, further preferably −3 nm to +3 nm, and particularly preferably −2 nm to +2 nm. When Re (550) and Rth (550) of the protective film are within such ranges, adverse effects on display characteristics can be prevented when the polarizing plate is applied to an image display device. Re (550) is the in-plane retardation of the film measured with light having a wavelength of 550 nm at 23 ° C. Re (550) is obtained by the formula: Re (550) = (nx−ny) × d. Rth (550) is a retardation in the thickness direction of the film measured with light having a wavelength of 550 nm at 23 ° C. Rth (550) is obtained by the formula: Rth (550) = (nx−nz) × d. Here, nx is the refractive index in the direction in which the in-plane refractive index is maximum (that is, the slow axis direction), and ny is in the direction orthogonal to the slow axis in the plane (that is, the fast axis direction). It is a refractive index, nz is the refractive index in the thickness direction, and d is the thickness (nm) of the film.

  The higher the light transmittance at 380 nm in the thickness of the protective film 80 μm, the better. Specifically, the light transmittance is preferably 85% or more, more preferably 88% or more, and further preferably 90% or more. If the light transmittance is within such a range, desired transparency can be ensured. The light transmittance can be measured, for example, by a method according to ASTM-D-1003.

  The haze of the protective film is preferably as low as possible. Specifically, the haze is preferably 5% or less, more preferably 3% or less, still more preferably 1.5% or less, and particularly preferably 1% or less. When the haze is 5% or less, the film can have a good clear feeling. Furthermore, even when used for the viewing-side polarizing plate of the image display device, the display content can be visually recognized well.

YI at a thickness of 80 μm of the protective film is preferably 1.27 or less, more preferably 1.25 or less, still more preferably 1.23 or less, and particularly preferably 1.20 or less. If YI exceeds 1.3, the optical transparency may be insufficient. YI is obtained from, for example, tristimulus values (X, Y, Z) of colors obtained by measurement using a high-speed integrating sphere type spectral transmittance measuring device (trade name DOT-3C: manufactured by Murakami Color Research Laboratory). The following equation can be used.
YI = [(1.28X−1.06Z) / Y] × 100

  The b value (scale of hue according to Hunter's color system) at a thickness of 80 μm of the protective film is preferably less than 1.5, more preferably 1.0 or less. If the b value is 1.5 or more, an undesired color may appear. The b value is obtained by, for example, cutting a protective film sample into a 3 cm square, measuring the hue using a high-speed integrating sphere type spectral transmittance measuring machine (trade name DOT-3C: manufactured by Murakami Color Research Laboratory), It can be obtained by evaluating the hue according to Hunter's color system.

The moisture permeability of the protective film is preferably 300 g / m ² · 24 hr or less, more preferably 250 g / m ² · 24 hr or less, still more preferably 200 g / m ² · 24 hr or less, particularly preferably 150 g / m ² · 24 hr or less, Most preferably, it is 100 g / m ² · 24 hr or less. When the moisture permeability of the protective film is in such a range, a polarizing plate excellent in durability and moisture resistance can be obtained.

  The tensile strength of the protective film is preferably 10 MPa or more and less than 100 MPa, more preferably 30 MPa or more and less than 100 MPa. If it is less than 10 MPa, sufficient mechanical strength may not be exhibited. If it exceeds 100 MPa, the workability may be insufficient. The tensile strength can be measured according to, for example, ASTM-D-882-61T.

  The tensile elongation of the protective film is preferably 1.0% or more, more preferably 3.0% or more, and further preferably 5.0% or more. The upper limit of tensile elongation is, for example, 100%. If the tensile elongation is less than 1%, the toughness may be insufficient. The tensile elongation can be measured, for example, according to ASTM-D-882-61T.

  The tensile elastic modulus of the protective film is preferably 0.5 GPa or more, more preferably 1 GPa or more, and further preferably 2 GPa or more. The upper limit of the tensile modulus is, for example, 20 GPa. If the tensile modulus is less than 0.5 GPa, sufficient mechanical strength may not be exhibited. A tensile elasticity modulus can be measured according to ASTM-D-882-61T, for example.

  The protective film may contain any appropriate additive depending on the purpose. Specific examples of additives include ultraviolet absorbers; hindered phenol-based, phosphorus-based, sulfur-based and other antioxidants; light-resistant stabilizers, weather-resistant stabilizers, heat stabilizers and other stabilizers; glass fibers, carbon fibers, etc. Near-infrared absorbers; flame retardants such as tris (dibromopropyl) phosphate, triallyl phosphate and antimony oxide; antistatic agents such as anionic, cationic and nonionic surfactants; inorganic pigments and organic pigments And colorants such as dyes; organic fillers or inorganic fillers; resin modifiers; organic fillers and inorganic fillers; plasticizers; lubricants; antistatic agents; An additive may be added at the time of superposition | polymerization of acrylic resin, and may be added at the time of film formation. The type, number, combination, addition amount, and the like of the additive can be appropriately set according to the purpose.

  In one embodiment, the second protective film can be formed of the same material as the first protective film. In another embodiment, the second protective film can be formed of a material different from that of the first protective film. When the second protective film is formed of a material different from that of the first protective film, examples of the material for forming the second protective film include acrylic resins that do not contain core-shell type particles, diacetyl cellulose, and triacetyl cellulose. Examples thereof include cellulose resins such as cycloolefin resins, olefin resins such as polypropylene, ester resins such as polyethylene terephthalate resins, polyamide resins, polycarbonate resins, and copolymer resins thereof. The thickness of the second protective film is preferably 10 μm to 100 μm.

C-2. Acrylic resin C-2-1. Configuration of Acrylic Resin Any appropriate acrylic resin can be adopted as the acrylic resin. The acrylic resin typically contains alkyl (meth) acrylate as a main component as a monomer unit. In this specification, “(meth) acryl” means acrylic and / or methacrylic. Examples of the alkyl (meth) acrylate constituting the main skeleton of the acrylic resin include linear or branched alkyl groups having 1 to 18 carbon atoms. These can be used alone or in combination. Furthermore, any appropriate copolymerization monomer may be introduced into the acrylic resin by copolymerization. The type, number, copolymerization ratio, and the like of such copolymerization monomers can be appropriately set according to the purpose. The constituent components (monomer units) of the main skeleton of the acrylic resin will be described later with reference to the general formula (2).

  The acrylic resin preferably has at least one selected from a glutarimide unit, a lactone ring unit, a maleic anhydride unit, a maleimide unit, and a glutaric anhydride unit. An acrylic resin having a lactone ring unit is described in, for example, Japanese Patent Application Laid-Open No. 2008-181078, and the description in the publication is incorporated herein by reference. The glutarimide unit is preferably represented by the following general formula (1):

In General Formula (1), R ¹ and R ² each independently represent hydrogen or an alkyl group having 1 to 8 carbon atoms, and R ³ represents an alkyl group having 1 to 18 carbon atoms or 3 to 12 carbon atoms. A cycloalkyl group or an aryl group having 6 to 10 carbon atoms. In the general formula (1), preferably, R ¹ and R ² are each independently hydrogen or a methyl group, and R ³ is hydrogen, a methyl group, a butyl group, or a cyclohexyl group. More preferably, R ¹ is a methyl group, R ² is hydrogen, and R ³ is a methyl group.

  The alkyl (meth) acrylate is typically represented by the following general formula (2):

In the general formula (2), R ⁴ represents a hydrogen atom or a methyl group, and R ⁵ represents a hydrogen atom or an optionally substituted aliphatic or alicyclic hydrocarbon group having 1 to 6 carbon atoms. Show. Examples of the substituent include halogen and hydroxyl group. Specific examples of the alkyl (meth) acrylate include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, n-butyl (meth) acrylate, and t- (meth) acrylate. Butyl, n-hexyl (meth) acrylate, cyclohexyl (meth) acrylate, chloromethyl (meth) acrylate, 2-chloroethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, (meth) acrylic acid Examples include 3-hydroxypropyl, 2,3,4,5,6-pentahydroxyhexyl (meth) acrylate and 2,3,4,5-tetrahydroxypentyl (meth) acrylate. In the general formula (2), R ⁵ is preferably a hydrogen atom or a methyl group. Accordingly, particularly preferred alkyl (meth) acrylates are methyl acrylate or methyl methacrylate.

The acrylic resin may contain only a single glutarimide unit, or may contain a plurality of glutarimide units in which R ¹ , R ² and R ³ in the general formula (1) are different.

  The content ratio of the glutarimide unit in the acrylic resin is preferably 2 mol% to 50 mol%, more preferably 2 mol% to 45 mol%, still more preferably 2 mol% to 40 mol%, and particularly preferably 2 mol%. % To 35 mol%, most preferably 3 mol% to 30 mol%. When the content ratio is less than 2 mol%, the effects expressed from the glutarimide unit (for example, high optical characteristics, high mechanical strength, excellent adhesiveness with a polarizer, thinning) are sufficiently exerted. There is a risk that it will not be. When the content ratio exceeds 50 mol%, for example, heat resistance and transparency may be insufficient.

The acrylic resin may include only a single alkyl (meth) acrylate unit, or may include a plurality of alkyl (meth) acrylate units in which R ⁴ and R ⁵ in the general formula (2) are different. Also good.

  The content ratio of the alkyl (meth) acrylate unit in the acrylic resin is preferably 50 mol% to 98 mol%, more preferably 55 mol% to 98 mol%, still more preferably 60 mol% to 98 mol%, particularly preferably. Is from 65 mol% to 98 mol%, most preferably from 70 mol% to 97 mol%. If the content ratio is less than 50 mol%, the effects expressed from the alkyl (meth) acrylate unit (for example, high heat resistance and high transparency) may not be sufficiently exhibited. If the content is more than 98 mol%, the resin is brittle and easily cracked, and high mechanical strength cannot be exhibited sufficiently, which may result in poor productivity.

  The acrylic resin may contain units other than glutarimide units and alkyl (meth) acrylate units.

  In one embodiment, acrylic resin can contain 0-10 weight% of unsaturated carboxylic acid units which are not concerned in the intramolecular imidation reaction mentioned later, for example. The content ratio of the unsaturated carboxylic acid unit is preferably 0 to 5% by weight, more preferably 0 to 1% by weight. When the content is in such a range, transparency, retention stability and moisture resistance can be maintained.

  In one embodiment, the acrylic resin may contain a copolymerizable vinyl monomer unit (other vinyl monomer units) other than those described above. Examples of other vinyl monomers include acrylonitrile, methacrylonitrile, ethacrylonitrile, allyl glycidyl ether, maleic anhydride, itaconic anhydride, N-methylmaleimide, N-ethylmaleimide, N-cyclohexylmaleimide, and acrylic. Aminoethyl acid, propylaminoethyl acrylate, dimethylaminoethyl methacrylate, ethylaminopropyl methacrylate, cyclohexylaminoethyl methacrylate, N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallylamine, N-methylallylamine, 2 -Isopropenyl-oxazoline, 2-vinyl-oxazoline, 2-acryloyl-oxazoline, N-phenylmaleimide, phenylaminoethyl methacrylate, styrene, α-me Rusuchiren, p- glycidyl styrene, p- aminostyrene, 2-styryl - and oxazoline and the like. These may be used alone or in combination. Styrene monomers such as styrene and α-methylstyrene are preferable. The content of other vinyl monomer units is preferably 0 to 1% by weight, more preferably 0 to 0.1% by weight. If it is such a range, the expression of the phase difference and the fall of transparency which are not desired can be suppressed.

The imidation ratio in the acrylic resin is preferably 2.5% to 20.0%. If the imidation ratio is in such a range, a resin excellent in heat resistance, transparency and molding processability can be obtained, and the occurrence of kogation and a decrease in mechanical strength during film molding can be prevented. In the acrylic resin, the imidization rate is represented by a ratio of a glutarimide unit and an alkyl (meth) acrylate unit. This ratio can be obtained from, for example, the NMR spectrum, IR spectrum, etc. of the acrylic resin. In the present embodiment, the imidization ratio can be determined by ¹ H-NMR measurement of a resin using ¹ HNMR BRUKER Avance III (400 MHz). More specifically, the peak area derived from the O—CH ₃ proton of alkyl (meth) acrylate in the vicinity of 3.5 to 3.8 ppm is defined as A, and N—CH ₃ of glutarimide in the vicinity of 3.0 to 3.3 ppm. The area of the proton-derived peak is represented by B, and is obtained by the following formula.
Imidation ratio Im (%) = {B / (A + B)} × 100

  The acid value of the acrylic resin is preferably 0.10 mmol / g to 0.50 mmol / g. If the acid value is within such a range, a resin having a good balance of heat resistance, mechanical properties and molding processability can be obtained. If the acid value is too small, there may be problems such as an increase in cost due to the use of a modifier for adjusting to a desired acid value, and generation of a gel-like material due to the remaining modifier. When the acid value is too large, foaming at the time of film forming (for example, at the time of melt extrusion) tends to occur, and the productivity of the molded product tends to decrease. In the acrylic resin, the acid value is the content of carboxylic acid units and carboxylic anhydride units in the acrylic resin. In the present embodiment, the acid value can be calculated by, for example, a titration method described in WO2005 / 054311 or JP-A-2005-23272.

  The weight average molecular weight of the acrylic resin is preferably 1,000 to 2,000,000, more preferably 5,000 to 1,000,000, still more preferably 10,000 to 500,000, particularly preferably 50,000 to 500,000, and most preferably 60000 to 150,000. A weight average molecular weight can be calculated | required by polystyrene conversion, for example using a gel permeation chromatograph (GPC system, product made from Tosoh). Tetrahydrofuran can be used as the solvent.

  The acrylic resin has a Tg (glass transition temperature) of preferably 110 ° C. or higher, more preferably 115 ° C. or higher, still more preferably 120 ° C. or higher, particularly preferably 125 ° C. or higher, and most preferably 130 ° C. or higher. If Tg is 110 degreeC or more, the polarizing plate containing the protective film obtained from such resin will become the thing excellent in durability. The upper limit value of Tg is preferably 300 ° C. or lower, more preferably 290 ° C. or lower, further preferably 285 ° C. or lower, particularly preferably 200 ° C. or lower, and most preferably 160 ° C. or lower. If Tg is in such a range, the moldability can be excellent.

C-2-2. Polymerization of acrylic resin The acrylic resin can be produced, for example, by the following method. This method comprises (I) an alkyl (meth) acrylate monomer corresponding to the alkyl (meth) acrylate unit represented by the general formula (2), an unsaturated carboxylic acid monomer and / or a precursor thereof To obtain a copolymer (a); and (II) treating the copolymer (a) with an imidizing agent to give a copolymer (a) in the copolymer (a). An intramolecular imidation reaction of the alkyl (meth) acrylate monomer unit and the unsaturated carboxylic acid monomer and / or its precursor monomer unit is carried out to share the glutarimide unit represented by the general formula (1). Introducing into the polymer.

  Examples of the unsaturated carboxylic acid monomer include acrylic acid, methacrylic acid, crotonic acid, α-substituted acrylic acid, and α-substituted methacrylic acid. Examples of the precursor monomer include acrylamide and methacrylamide. These may be used alone or in combination. A preferred unsaturated carboxylic acid monomer is acrylic acid or methacrylic acid, and a preferred precursor monomer is acrylamide.

  Any appropriate method can be used as a method for treating the copolymer (a) with an imidizing agent. Specific examples include a method using an extruder and a method using a batch type reaction vessel (pressure vessel). The method using an extruder includes heating and melting the copolymer (a) using an extruder and treating it with an imidizing agent. In this case, any appropriate extruder can be used as the extruder. Specific examples include a single screw extruder, a twin screw extruder, and a multi-screw extruder. In the method using a batch type reaction vessel (pressure vessel), any appropriate batch type reaction vessel (pressure vessel) can be used.

  As the imidizing agent, any appropriate compound can be used as long as the glutarimide unit represented by the general formula (1) can be generated. Specific examples of the imidizing agent include amines containing aliphatic hydrocarbon groups such as methylamine, ethylamine, n-propylamine, i-propylamine, n-butylamine, i-butylamine, tert-butylamine, n-hexylamine, Examples include aromatic hydrocarbon group-containing amines such as aniline, benzylamine, toluidine, and trichloroaniline, and alicyclic hydrocarbon group-containing amines such as cyclohexylamine. Furthermore, for example, a urea compound that generates such an amine by heating can be used. Examples of the urea compound include urea, 1,3-dimethylurea, 1,3-diethylurea, and 1,3-dipropylurea. The imidizing agent is preferably methylamine, ammonia, or cyclohexylamine, more preferably methylamine.

  In imidation, in addition to the imidizing agent, a ring closure accelerator may be added as necessary.

  The amount of the imidizing agent used in the imidization is preferably 0.5 to 10 parts by weight, more preferably 0.5 to 6 parts by weight with respect to 100 parts by weight of the copolymer (a). It is. If the amount of the imidizing agent used is less than 0.5 parts by weight, the desired imidization rate is often not achieved. As a result, the heat resistance of the resulting resin becomes extremely insufficient, which may induce appearance defects such as burnt after molding. When the amount of the imidizing agent used exceeds 10 parts by weight, the imidizing agent remains in the resin, and the imidizing agent may induce appearance defects such as burnt after molding and foaming.

  The manufacturing method of this embodiment can include the process by an esterifying agent in addition to the said imidation as needed.

  Examples of the esterifying agent include dimethyl carbonate, 2,2-dimethoxypropane, dimethyl sulfoxide, triethyl orthoformate, trimethyl orthoacetate, trimethyl orthoformate, diphenyl carbonate, dimethyl sulfate, methyl toluene sulfonate, methyl trifluoromethyl sulfonate. , Methyl acetate, methanol, ethanol, methyl isocyanate, p-chlorophenyl isocyanate, dimethylcarbodiimide, dimethyl-t-butylsilyl chloride, isopropenyl acetate, dimethylurea, tetramethylammonium hydroxide, dimethyldiethoxysilane, tetra-N-butoxy Silane, dimethyl (trimethylsilane) phosphite, trimethyl phosphite Trimethyl phosphate, tricresyl phosphate, diazomethane, ethylene oxide, propylene oxide, cyclohexene oxide, 2-ethylhexyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether. Among these, dimethyl carbonate is preferable from the viewpoint of cost and reactivity.

  The addition amount of the esterifying agent can be set so that the acid value of the acrylic resin becomes a desired value.

C-2-3. Combined use of other resins In the embodiment of the present invention, the acrylic resin and other resins may be used in combination. That is, the monomer component constituting the acrylic resin and the monomer component constituting the other resin may be copolymerized, and the copolymer may be used for film formation described later in Section D; the acrylic resin and the other resin. The blend may be used for film formation. Other resins include, for example, styrene resins, polyethylene, polypropylene, polyamide, polyphenylene sulfide, polyether ether ketone, polyester, polysulfone, polyphenylene oxide, polyacetal, polyimide, polyetherimide, and other thermoplastic resins, phenolic Examples thereof include thermosetting resins such as resins, melamine resins, polyester resins, silicone resins, and epoxy resins. The type and blending amount of the resin to be used in combination can be appropriately set according to the purpose and the properties desired for the obtained film. For example, a styrene resin (preferably, acrylonitrile-styrene copolymer) can be used in combination as a retardation control agent.

  When using together acrylic resin and other resin, content of acrylic resin in the blend of acrylic resin and other resin becomes like this. Preferably it is 50 to 100 weight%, More preferably, it is 60 to 100 weight%. % By weight, more preferably 70% by weight to 100% by weight, particularly preferably 80% by weight to 100% by weight. When the content is less than 50% by weight, the high heat resistance and high transparency inherent in the acrylic resin may not be sufficiently reflected.

C-3. Core-shell type particles In the protective film, the core-shell type particles are preferably blended in an amount of 3 to 50 parts by weight, more preferably 3 to 40 parts by weight with respect to 100 parts by weight of the acrylic resin. Thereby, arithmetic mean roughness Ra of the surface of a protective film can be adjusted in a desired range. The core-shell type particles may be partially exposed on the surface of the protective film to form irregularities on the surface of the protective film, or may not be exposed on the surface of the protective film (in a state covered with an acrylic resin). ) Unevenness may be formed on the surface of the protective film.

  The core-shell type particle typically has a core made of a rubber-like polymer and a coating layer made of a glass-like polymer and covering the core. The core-shell type particle may have one or more layers made of a glassy polymer as the innermost layer or the intermediate layer.

  The Tg of the rubbery polymer constituting the core is preferably 20 ° C. or less, more preferably −60 ° C. to 20 ° C., and further preferably −60 ° C. to 10 ° C. If the Tg of the rubbery polymer constituting the core exceeds 20 ° C, the mechanical strength of the acrylic resin may not be sufficiently improved. Tg of the glassy polymer (hard polymer) constituting the coating layer is preferably 50 ° C or higher, more preferably 50 ° C to 140 ° C, and further preferably 60 ° C to 130 ° C. When Tg of the glassy polymer constituting the coating layer is lower than 50 ° C., the heat resistance of the acrylic resin may be lowered.

  The core content in the core-shell type particles is preferably 30% by weight to 95% by weight, more preferably 50% by weight to 90% by weight. The ratio of the glassy polymer layer in the core is 0 to 60% by weight, preferably 0 to 45% by weight, and more preferably 10 to 40% by weight with respect to 100% by weight of the total amount of the core. The content of the coating layer in the core-shell type particles is preferably 5% by weight to 70% by weight, more preferably 10% by weight to 50% by weight.

In one embodiment, the core-shell particles dispersed in the acrylic resin may have a flat shape. The core-shell type particles can be flattened by stretching described later in Section C-4. The length / thickness ratio of the flattened core-shell type particles is 7.0 or less. The length / thickness ratio is preferably 6.5 or less, and more preferably 6.3 or less. On the other hand, the length / thickness ratio is preferably 4.0 or more, more preferably 4.5 or more, and further preferably 5.0 or more. In the present specification, the “ratio of length / thickness” means the ratio of the representative length and thickness of the core-shell type particle in plan view. Here, the “representative length” means a diameter when the shape in plan view is circular, a long diameter when the shape is elliptical, and a diagonal length when the shape is rectangular or polygonal. The ratio can be obtained, for example, by the following procedure. The cross section of the obtained film was photographed with a transmission electron microscope (for example, acceleration voltage 80 kV, RuO ₄ dyeing ultrathin section method), and the long core-shell type particles present in the obtained photograph (cross section close to the representative length) The ratio can be obtained by extracting 30 pieces in order from the one obtained and calculating (average length) / (average thickness).

  Details of the rubber-like polymer constituting the core of the core-shell type particle, the glassy polymer (hard polymer) constituting the coating layer, the polymerization method thereof, and other constitutions are disclosed in, for example, JP-A-2016-33552. It is described in. The description of this publication is incorporated herein by reference.

C-4. Formation of Protective Film A protective film according to an embodiment of the present invention typically comprises the above acrylic resin (in the case of using another resin in combination, a blend with the other resin) and a core-shell type particle. Can be formed by a method comprising filming. Further, the method of forming the protective film can include stretching the film.

  The average particle diameter of the core-shell type particles used for film formation is preferably 1 nm to 500 nm. If it is such an average particle diameter, the arithmetic mean roughness Ra of the surface of the protective film obtained can be adjusted in a desired range. The average particle diameter of the core is preferably 50 nm to 300 nm, more preferably 70 nm to 300 nm.

  Arbitrary appropriate methods can be employ | adopted as a method of forming a film. Specific examples include cast coating methods (for example, casting methods), extrusion molding methods, injection molding methods, compression molding methods, transfer molding methods, blow molding methods, powder molding methods, FRP molding methods, calendar molding methods, and hot presses. Law. The extrusion molding method or the cast coating method is preferable. This is because the smoothness of the resulting film can be improved and good optical uniformity can be obtained. Particularly preferred is an extrusion method. This is because it is not necessary to consider the problem due to the residual solvent. Among these, an extrusion method using a T die is preferable from the viewpoint of film productivity and ease of subsequent stretching treatment. The molding conditions can be appropriately set according to the composition and type of the resin used, the properties desired for the resulting film, and the like.

  Any appropriate stretching method and stretching conditions (for example, stretching temperature, stretching ratio, stretching speed, stretching direction) can be adopted as the stretching method. Specific examples of the stretching method include free end stretching, fixed end stretching, free end contraction, and fixed end contraction. These may be used alone, may be used simultaneously, or may be used sequentially. By stretching a film in which the blending amount of core-shell type particles with respect to the acrylic resin is appropriately adjusted under appropriate stretching conditions, the core-shell type particles move (bleed) to the surface of the film, resulting in unevenness on the film surface. The arithmetic average roughness Ra of the surface of the obtained protective film can be adjusted within the desired range.

  As the stretching direction, an appropriate direction can be adopted depending on the purpose. Specifically, a length direction, a width direction, a thickness direction, and an oblique direction are mentioned. The stretching direction may be one direction (uniaxial stretching), two directions (biaxial stretching), or three or more directions. In the embodiment of the present invention, typically, uniaxial stretching in the length direction, simultaneous biaxial stretching in the length direction and width direction, and sequential biaxial stretching in the length direction and width direction may be employed. Biaxial stretching (simultaneous or sequential) is preferable. This is because the in-plane phase difference can be easily controlled and optical isotropy can be easily realized.

  Stretching temperature is the optical properties, mechanical properties and thickness desired for the protective film, type of resin used, film thickness used, stretching method (uniaxial stretching or biaxial stretching), stretching ratio, stretching speed It can vary depending on the like. Specifically, the stretching temperature is preferably Tg to Tg + 50 ° C, more preferably Tg + 15 ° C to Tg + 50 ° C, and most preferably Tg + 35 ° C to Tg + 50 ° C. By stretching at such a temperature, a protective film having appropriate characteristics can be obtained. The specific stretching temperature is, for example, 110 ° C to 200 ° C, preferably 120 ° C to 190 ° C. If the stretching temperature is in such a range, the core-shell type particles bleed on the surface of the film by appropriately adjusting the stretching ratio and the stretching speed, and the arithmetic average roughness Ra of the surface of the resulting protective film is the above desired value. Can be adjusted within the range.

  The stretching ratio is also the same as the stretching temperature, the arithmetic average roughness Ra of the surface desired for the protective film, optical properties, mechanical properties and thickness, the type of resin used, the thickness of the film used, the stretching It may vary depending on the method (uniaxial stretching or biaxial stretching), stretching temperature, stretching speed, and the like. When employing biaxial stretching, the ratio (TD / MD) of the stretching ratio in the width direction (TD) and the stretching ratio in the length direction (MD) is preferably 1.0 to 1.5, more preferably. Is 1.0 to 1.4, more preferably 1.0 to 1.3. Moreover, the surface magnification (product of the draw ratio in the length direction and the draw ratio in the width direction) in the case of employing biaxial stretching is preferably 2.0 to 6.0, more preferably 3.0 to 5.5, and more preferably 3.5 to 5.2. When the draw ratio is in such a range, the core-shell type particles bleed on the surface of the film by appropriately adjusting the drawing temperature and the drawing speed, and the arithmetic average roughness Ra of the surface of the protective film to be obtained is the above desired value. Can be adjusted within the range.

  The stretching speed is also the same as the stretching temperature, the arithmetic average roughness Ra of the surface desired for the protective film, optical properties, mechanical properties and thickness, the type of resin used, the thickness of the film used, the stretching It may vary depending on the method (uniaxial stretching or biaxial stretching), stretching temperature, stretching ratio, and the like. The stretching speed is preferably 3% / second to 20% / second, more preferably 3% / second to 15% / second, and further preferably 3% / second to 10% / second. When biaxial stretching is employed, the stretching speed in one direction and the stretching speed in the other direction may be the same or different. When the stretching speed is in such a range, the core-shell type particles bleed on the surface of the film by appropriately adjusting the stretching temperature and the stretching ratio, and the arithmetic average roughness Ra of the surface of the protective film to be obtained is the above desired value. Can be adjusted within the range.

  As described above, a protective film can be formed.

D. Image Display Device The polarizing plate described in the above items A to C can be applied to an image display device. Therefore, the present invention also includes an image display device using such a polarizing plate. Typical examples of the image display device include a liquid crystal display device and an organic electroluminescence (EL) display device. The image display device typically includes a display cell, a polarizing plate, a diffusion sheet, and a light source (backlight) in this order, and a protective film for the polarizing plate is disposed to face the diffusion sheet.

EXAMPLES Hereinafter, although an Example demonstrates this invention concretely, this invention is not limited by these Examples. The measuring method of each characteristic is as follows. Unless otherwise specified, “parts” and “%” in the examples are based on weight.
(1) Thickness It was measured using a digital micrometer (manufactured by Anritsu, product name “KC-351C”).
(2) Arithmetic average roughness Ra of the surface of the protective film
Arithmetic average roughness Ra was measured using an optical profilometer (manufactured by Veeco Instruments, trade name “Optical Profilometer NT3300”).
(3) Scratch evaluation On a glass plate (MICRO SLIDE GLASS Pre-cleaned water green polish t1.3 (manufactured by MATSANAMI), product model number “S200393”, size: 65 × 165 mm, Thickness 1.2 to 1.5 mm), 50 mm × A laminate of a glass plate and a polarizing plate was produced by bonding the polarizing plate cut to a size of 1500 mm via an adhesive layer. The laminated body reproduces the configuration of the liquid crystal panel in a pseudo manner.
A diffusion sheet (manufactured by Sumitomo 3M Ltd., product name “DBEF-D2-400”) is placed in the tray, and the laminate is placed on the diffusion sheet with the polarizing plate side down. did. Next, the tray was shaken under the condition of 200 times / min × 10 min. Thereafter, the laminate was taken out, and the presence or absence of abrasion scratches (rubbing lump) on the first protective film of the polarizing plate was visually confirmed.

<Example 1>
(Preparation of polarizing plate)
1. Production of protective film MS resin (MS-200; copolymer of methyl methacrylate / styrene (molar ratio) = 80/20, manufactured by Nippon Steel Chemical Co., Ltd.) is imidized with monomethylamine (imidation ratio: 5) %)did. The obtained imidized MS resin is represented by a general formula (1), a glutarimide unit (R ¹ and R ³ are methyl groups, R ² is a hydrogen atom), and a general formula (2) ( It had a (meth) acrylic acid ester unit (R ⁴ is a hydrogen atom, R ⁵ and R ⁶ are methyl groups), and a styrene unit. For the imidization, a meshing type co-rotating twin screw extruder having a diameter of 15 mm was used. The set temperature of each temperature control zone of the extruder is 230 ° C., the screw rotation speed is 150 rpm, MS resin is supplied at 2.0 kg / hr, and the supply amount of monomethylamine is 2 parts by weight with respect to 100 parts by weight of MS resin. did. MS resin was introduced from the hopper, and the resin was melted and filled with a kneading block, and then monomethylamine was injected from the nozzle. A seal ring was placed at the end of the reaction zone to fill the resin. By-products after the reaction and excess methylamine were devolatilized by reducing the pressure at the vent port to -0.08 MPa. The resin that came out as a strand from a die provided at the exit of the extruder was cooled in a water tank and then pelletized with a pelletizer. The imidization rate of the obtained imidized MS resin was 5.0%, and the acid value was 0.5 mmol / g.
100 parts by weight of the imidized MS resin obtained above and 10 parts by weight of core-shell type particles were put into a single screw extruder, melt mixed, and a film was formed through a T die to obtain an extruded film having a thickness of 40 μm. . The obtained extruded film was simultaneously biaxially stretched twice in the length direction and the width direction at a stretching temperature of 160 ° C. The stretching speed was 10% / second in both the length direction and the width direction.
In this way, a protective film was produced. The obtained protective film had a thickness of 10 μm, an arithmetic surface roughness Ra of 22.18 μm, an in-plane retardation Re (550) of 2 nm, and a thickness direction retardation Rth (550) of 2 nm.
2. Production of polarizer A long roll of polyvinyl alcohol (PVA) resin film (product name “PE3000”, manufactured by Kuraray Co., Ltd.) having a thickness of 30 μm is uniaxial in the longitudinal direction so as to be 5.9 times in the longitudinal direction by a roll stretching machine. Swelling, dyeing, cross-linking and washing were simultaneously performed while stretching, and finally a drying process was performed to prepare a polarizer having a thickness of 12 μm.
Specifically, the swelling treatment was stretched 2.2 times while being treated with pure water at 20 ° C. Next, the dyeing treatment is performed in an aqueous solution at 30 ° C. in which the weight ratio of iodine and potassium iodide is 1: 7, the iodine concentration of which is adjusted so that the single transmittance of the obtained polarizer is 45.0%. The film was stretched 1.4 times. Furthermore, the crosslinking treatment employed a two-stage crosslinking treatment, and the first-stage crosslinking treatment was stretched 1.2 times while being treated in an aqueous solution in which boric acid and potassium iodide were dissolved at 40 ° C. The boric acid content of the aqueous solution of the first-stage crosslinking treatment was 5.0% by weight, and the potassium iodide content was 3.0% by weight. The cross-linking treatment at the second stage was stretched 1.6 times while being treated in an aqueous solution in which boric acid and potassium iodide were dissolved at 65 ° C. The boric acid content of the aqueous solution of the second crosslinking treatment was 4.3% by weight, and the potassium iodide content was 5.0% by weight. In addition, the cleaning treatment was performed with an aqueous potassium iodide solution at 20 ° C. The potassium iodide content of the aqueous solution for the washing treatment was 2.6% by weight. Finally, the drying process was performed at 70 ° C. for 5 minutes to obtain a polarizer.
3. Production of polarizing plate (second protective film)
The protective film obtained above as a first protective film is bonded to one surface of the polarizer via a polyvinyl alcohol-based adhesive, and the polyvinyl alcohol-based adhesive is bonded to the other surface of the polarizer. Then, a TAC film (manufactured by Dai Nippon Printing Co., Ltd., trade name “DSG-03”, thickness 70 μm) was bonded as a second protective film.
(Adhesive layer)
In a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer, and a stirring device, 94.9 parts of butyl acrylate, 5 parts of acrylic acid, 0.1 part of 2-hydroxyethyl acrylate, and dibenzoyl peroxide were added. After adding 0.3 parts of ethyl acetate with 100 parts of the total monomer (solid content) and reacting at 60 ° C. for 7 hours under a nitrogen gas stream, ethyl acetate was added to the reaction solution to obtain a weight average molecular weight. A solution containing an acrylic polymer (B) having 2.2 million and a dispersion ratio of 3.9 was obtained (solid content concentration 30%). 0.6 part of trimethylolpropane tolylene diisocyanate (manufactured by Nippon Polyurethane Industry Co., Ltd .: Coronate L) and 0.075 part of γ− per 100 parts of the solid content of the solution containing the acrylic polymer (B) Glycidoxypropylmethoxysilane (manufactured by Shin-Etsu Chemical Co., Ltd .: KBM-403) was blended to obtain an adhesive solution. The above-mentioned solution was diluted with ethyl acetate so that the solid content concentration was 15% to prepare an adhesive coating solution. The adhesive coating solution prepared above is applied to one side of a 38 μm polyethylene terephthalate (PET) film (MRF38, manufactured by Mitsubishi Chemical Polyester Film Co., Ltd.), which has been subjected to silicone treatment, to a coating thickness of 134.0 μm. As described above, coating was performed using a fountain die coater. Subsequently, drying was performed at 155 ° C. for 1 minute to form an adhesive layer having a thickness of 20 μm. The said adhesive layer was transcribe | transferred to the surface of the said TAC film, and the polarizing plate (with an adhesive layer) was produced. The obtained polarizing plate was subjected to the above evaluation. The results are shown in Table 1.

<Example 2>
A protective film was prepared in the same manner as in Example 1 except that an extruded film having a thickness of 80 μm was formed and this extruded film was used. The resulting protective film had a thickness of 20 μm and an arithmetic average roughness Ra of 12.37 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 3>
A protective film was prepared in the same manner as in Example 1 except that an extruded film having a thickness of 160 μm was formed and this extruded film was used. The resulting protective film had a thickness of 40 μm and an arithmetic average roughness Ra of 6.48 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 4>
A protective film was prepared in the same manner as in Example 1 except that an extruded film having a thickness of 120 μm was formed and this extruded film was used. The resulting protective film had a thickness of 30 μm and an arithmetic average roughness Ra of 8.17 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 5>
Extruded film was formed by putting 100 parts by weight of imidized MS resin and 3 parts by weight of core-shell type particles into a single-screw extruder and melt-mixing them. The same procedure as in Example 4 was conducted except that this extruded film was used. A protective film was created. The obtained protective film had a thickness of 30 μm and an arithmetic average roughness Ra of 6.11 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 6>
100 parts by weight of imidized MS resin and 5 parts by weight of core-shell type particles were put into a single screw extruder and melt mixed to form an extruded film. Except for using this extruded film, the same procedure as in Example 4 was performed. A protective film was created. The obtained protective film had a thickness of 30 μm and an arithmetic average roughness Ra of 6.79 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 7>
Extruded film was formed by putting 100 parts by weight of imidized MS resin and 20 parts by weight of core-shell type particles into a single-screw extruder and melt-mixing them. The same procedure as in Example 4 was conducted except that this extruded film was used. A protective film was created. The thickness of the obtained protective film was 30 μm, and the arithmetic average roughness Ra was 23.45 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 8>
Extruded film was formed by putting 100 parts by weight of imidized MS resin and 30 parts by weight of core-shell type particles into a single-screw extruder and melt-mixing them. The same procedure as in Example 4 was conducted except that this extruded film was used. A protective film was created. The obtained protective film had a thickness of 30 μm and an arithmetic average roughness Ra of 31.37 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 9>
Extruded film was formed by putting 100 parts by weight of imidized MS resin and 40 parts by weight of core-shell type particles into a single-screw extruder and melt-mixing them, and the same procedure as in Example 4 except that this extruded film was used. A protective film was created. The obtained protective film had a thickness of 30 μm and an arithmetic average roughness Ra of 32.79 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 10>
A protective film was prepared in the same manner as in Example 4 except that the obtained extruded film was stretched at a stretching temperature of 140 ° C. The resulting protective film had a thickness of 30 μm and an arithmetic average roughness Ra of 8.06 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 11>
A protective film was prepared in the same manner as in Example 4 except that the obtained extruded film was stretched at a stretching temperature of 130 ° C. The obtained protective film had a thickness of 30 μm and an arithmetic average roughness Ra of 6.72 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 12>
A protective film was prepared in the same manner as in Example 4 except that the obtained extruded film was stretched at a stretching temperature of 170 ° C. The obtained protective film had a thickness of 30 μm and an arithmetic average roughness Ra of 15.76 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Example 13>
A protective film was prepared in the same manner as in Example 4 except that the obtained extruded film was stretched at a stretching temperature of 180 ° C. The resulting protective film had a thickness of 30 μm and an arithmetic average roughness Ra of 17.29 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative Example 1>
A protective film was formed in the same manner as in Example 3 except that only an imidized MS resin was introduced into a single screw extruder and melt-mixed to form an extruded film, and the obtained extruded film was stretched at a stretching temperature of 145 ° C. It was created. The obtained protective film had a thickness of 40 μm and an arithmetic average roughness Ra of 4.2 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative Example 2>
Extruded film was formed by putting 100 parts by weight of imidized MS resin and 1 part by weight of core-shell type particles into a single screw extruder and melt-mixing them, and the same procedure as in Example 3 except that this extruded film was used. A protective film was created. The resulting protective film had a thickness of 40 μm and an arithmetic average roughness Ra of 4.93 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

<Comparative Example 3>
Except that 100 parts by weight of imidized MS resin and 5 parts by weight of core-shell type particles were put into a single screw extruder and melt mixed to form an extruded film, and the resulting extruded film was stretched at a stretching temperature of 100 ° C. Prepared a protective film in the same manner as in Example 3. The resulting protective film had a thickness of 40 μm and an arithmetic average roughness Ra of 5.14 μm. A polarizing plate was produced in the same manner as in Example 1 except that the protective film was used. The polarizing plate was subjected to the same evaluation as in Example 1. The results are shown in Table 1.

  As is clear from Table 1, the polarizing plates of Comparative Examples 1 to 3 were abraded by being shaken in contact with the diffusion sheet, but the polarizing plates of Examples 1 to 13 were the diffusion sheet. No wear scars were caused even when shaken in contact with the.

  The polarizing plate of this invention is used suitably for an image display apparatus. The image display device according to the present invention includes portable devices such as personal digital assistants (PDAs), smart phones, mobile phones, watches, digital cameras, and portable game machines; OA devices such as personal computer monitors, notebook computers, and copy machines; Household electrical equipment such as microwave ovens; back monitors, car navigation system monitors, car audio equipment such as car audio; display equipment such as digital signage and commercial store information monitors; security equipment such as monitoring monitors; It can be used for various purposes such as nursing care / medical equipment such as medical monitors and medical monitors.

DESCRIPTION OF SYMBOLS 1 Polarizer 2 Protective film 3 Second protective film 10 Polarizing plate 11 Polarizing plate

Claims (8)

A polarizer, and a protective film disposed on at least one side of the polarizer,
The protective film includes an acrylic resin and core-shell particles dispersed in the acrylic resin,
The polarizing plate whose arithmetic mean roughness Ra of the surface of the said protective film is 6.0 micrometers or more.   The polarizing plate according to claim 1, wherein the acrylic resin has at least one selected from the group consisting of a glutarimide unit, a lactone ring unit, a maleic anhydride unit, a maleimide unit, and a glutaric anhydride unit.   The polarizing plate of Claim 1 or 2 with which the unevenness | corrugation by the said core-shell type particle | grains is formed in the surface on the opposite side to the said polarizer of the said protective film.   The polarizing plate according to any one of claims 1 to 3, wherein the protective film contains 3 to 50 parts by weight of the core-shell type particles with respect to 100 parts by weight of the acrylic resin.   The polarizing plate according to any one of claims 1 to 4, wherein the core-shell type particle has a core made of a rubber-like polymer and a coating layer made of a glassy polymer and covering the core.   The polarizing plate according to claim 1, wherein the protective film is a biaxially stretched film.   The polarizing plate in any one of Claim 1 to 6 which does not have a diffusion layer on the surface of the said protective film. A display cell, the polarizing plate according to any one of claims 1 to 7, a diffusion sheet, and a light source are provided in this order,
The image display device, wherein the protective film of the polarizing plate is disposed to face the diffusion sheet.

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