TWI766004B - Optical laminate, polarizing plate, and image display device - Google Patents

Abstract

The present invention provides an optical laminate having excellent appearance. The optical layered product of the present invention includes a base film containing an acrylic resin, and a surface treatment layer formed on one side of the base film, and constitutes a position at a depth of 3.0 μm in the direction of the surface treatment layer from the base film side. Among the components, the ratio of the components of the acrylic resin eluted to the surface treatment layer is 18% or more.

Description

Optical laminate, polarizing plate, and image display device

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

In recent years, there has been known an optical laminate in which functional layers (surface treatment layers) such as a hard coat layer, an antiglare layer, and an antireflection layer are formed on one side of a base film containing an acrylic resin (Patent Document 1). Such an optical laminate can be used, for example, as a protective film of a polarizing element or a front panel of an image display device. Prior Art Documents Patent Documents

Patent Document 1: Japanese Patent Laid-Open No. 2016-218478

[Problems to be Solved by Invention]

However, in the case where the acrylic resin film is damaged in the conventional optical laminate as described above, there is a problem that the damage becomes apparent due to the formation of the surface treatment layer. This phenomenon occurs even when the damage generated on the acrylic resin film is so small that it cannot be seen visually, and the unobservable damage can become a visually poor appearance in the optical laminate obtained. reason.

The present invention has been accomplished in order to solve the aforementioned problems, and its main object is to provide an optical laminate having excellent appearance, a polarizing plate including such an optical laminate, and an image display device including such a polarizing plate. [Technical means to solve problems]

The optical laminate of the present invention includes a base film containing an acrylic resin, and a surface treatment layer formed on one side of the base film, and has a depth of 3.0 μm in the direction of the surface treatment layer from the base film side The ratio of the component of the acrylic resin eluted to the surface treatment layer among the components at the position is 18% or more. In one embodiment, the refractive index of the base film is set to R1, the refractive index of the surface treatment layer is set to R2, and the depth from the base film side in the direction of the surface treatment layer is 3.0 μm. When the refractive index of the position is set to R3, R3≦0.18R1+0.82R2 (wherein, R1<R2) is satisfied. In one embodiment, the thickness of the surface treatment layer is 3 μm˜20 μm. In one Embodiment, the said base film contains the said acrylic resin and the core-shell type particle|grains dispersed in the said acrylic resin. In one Embodiment, the said base film contains 3 weight part - 50 weight part of said core-shell type particle|grains with respect to 100 weight part of said acrylic resins. In one embodiment, the acrylic resin is 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. at least one of them. In one embodiment, the surface treatment layer is a hardened layer of the resin coated on the base film. In one embodiment, the surface treatment layer is at least one selected from the group consisting of a hard coat layer, an anti-glare layer, and an anti-reflection layer. According to another aspect of the present invention, a polarizing plate is provided. The polarizing plate includes a polarizing element and a protective layer disposed on one side of the polarizing element, and the protective layer is the optical laminate. According to another aspect of the present invention, an image display device is provided. This image display device includes the above-described polarizing plate. [Effect of invention]

According to the present invention, by constituting a component at a depth of 3.0 μm in the direction of the surface treatment layer from the base film side, the component of the acrylic resin eluted into the surface treatment layer is 18% or more, so that a good appearance can be provided. An excellent optical laminate, a polarizing plate provided with such an optical laminate, and an image display device provided with such a polarizing plate.

Hereinafter, embodiments of the present invention will be described, but the present invention is not limited to these embodiments.

A. Overall Configuration of Optical Laminate Figure 1 is a schematic cross-sectional view of an optical laminate according to an embodiment of the present invention. The optical laminate 100 includes a base film 10 and a surface treatment layer 20 formed on one side of the base film 10 . In the optical layered body 100 , the ratio of the component of the acrylic resin eluted to the surface treatment layer among the components constituting the position at a depth of 3.0 μm in the direction of the surface treatment layer 20 from the base film 10 side is 18% or more. The position with a depth of 3.0 μm in the direction of the surface treatment layer from the base film side is typically a position separated by 3.0 μm in the direction of the surface treatment layer from the interface between the base film and the surface treatment layer. The ratio of the components of the acrylic resin at the "position at the depth of 3 μm" is typically derived by the following method. Calculated position of the acrylic resin component (position from the surface treatment side) = thickness of the surface treatment layer (thickness of the PET substrate hard coat layer) - (3 μm) For example, when (the thickness of the PET substrate hard coat layer) is 15 μm In this case, the ratio of the acrylic resin component at a position of 12 μm from the surface treatment side was measured. The thickness of the surface treatment layer (thickness of the hard coat layer) is typically derived by the following procedure. First, a PET substrate (manufactured by Toray Corporation, trade name: U48-3, refractive index: 1.60) was used as a substrate film, dried at a heating temperature of 70° C. for the coating layer, and subjected to UV curing, thereby obtaining a formed Optical laminate with hard coat. A black acrylic resin plate (manufactured by Mitsubishi Rayon Co., Ltd., thickness 2 mm) was attached to the base material layer side of the obtained optical laminate via an acrylic adhesive with a thickness of 20 μm. Next, the reflection spectrum of the hard coat layer was measured under the following conditions using an instantaneous multi-channel photometric system (manufactured by Otsuka Electronics Co., Ltd., trade name: MCPD3700). Since the composition for forming a hard coat layer does not penetrate into the PET base material used for these laminates, it was determined from the peak positions of the FFT (fast Fourier transform) spectrum obtained from the laminates that only the hard coat layer was The thickness of the coating.・Reflectance spectrum measurement conditions reference: Mirror algorithm: FFT method calculation wavelength: 450 nm to 850 nm ・Detection conditions Exposure time: 20 ms Lamp gain: normal accumulation times: 10 times ・FFT method film thickness value Range: 2～15 μm Film Thickness Resolution: 24 nm

The above ratio is preferably 18% to 30%, more preferably 18.5% to 25%. The ratio of the component of the acrylic resin eluted to the surface treatment layer among the components constituting the position of the 3.0 μm depth in the direction of the surface treatment layer 20 from the base film 10 side can be measured, for example, by the pyran coupling method. Specifically, let R1 be the refractive index of the base film, and R2 be the refractive index of the surface treatment layer, and set the direction of the surface treatment layer from the base film side to 3.0 μm as measured by the H-coupling method. When the refractive index at the depth position is set to R3, the ratio X (%) of the component of the acrylic resin eluted to the surface treatment layer among the components constituting the position at a depth of 3.0 μm in the direction of the surface treatment layer from the base film side is It is expressed as follows. X(%)=(R3−R2)×100/(R1−R2) Therefore, the refractive index R1 of the optical laminate 100 and the base film, the refractive index R2 of the surface treatment layer, and the surface along the surface from the base film side The index of refraction R3 at a depth of 3.0 μm in the direction of the treatment layer is related to preferably satisfy the following inequality. R3≦0.18R1+0.82R2 (R1＜R2) The thickness of the surface treatment layer is preferably 3 μm to 20 μm, more preferably 5 μm to 15 μm. In one embodiment, the base film 10 contains an acrylic resin and core-shell particles dispersed in the acrylic resin. In this case, the base film 10 preferably contains 3 parts by weight to 50 parts by weight of the core-shell particles with respect to 100 parts by weight of the acrylic resin. The acrylic resin preferably 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 surface treatment layer 20 is typically a hardened layer of the resin composition coated on the base film 10 . The surface treatment layer 20 is preferably at least one selected from the group consisting of a hard coat layer, an anti-glare layer and an anti-reflection layer. In the conventional optical layered product, the damage in the longitudinal direction caused by winding up the elongated base film on a roll may become apparent due to the formation of the surface treatment layer on the base film. On the other hand, according to the optical layered body 100 of the present invention, the elution amount of the acrylic resin contained in the base film 10 to the surface treatment layer 20 is sufficiently large. Thereby, the apparent damage of the base film 10 due to the formation of the surface treatment layer 20 on the base film 10 can be suppressed. Furthermore, the adhesiveness of the base film 10 and the surface treatment layer 20 can be improved.

B. Base film B-1. Characteristics of base film The base film contains an acrylic resin as described above. In one embodiment, the base film contains an acrylic resin and core-shell particles dispersed in the acrylic resin. The thickness of the base film is preferably 5 μm to 150 μm, more preferably 10 μm to 100 μm. When the surface treatment layer described below is formed on the base film, the acrylic resin is eluted to the surface treatment layer. When the acrylic resin is eluted into the surface treatment layer, the ratio of the acrylic resin component in the component constituting the position of the depth of 3.0 μm in the direction of the surface treatment layer from the base film side becomes 18% or more.

The base film preferably has substantially optical isotropy. 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. The in-plane retardation Re(550) is more preferably 0 nm to 5 nm, more preferably 0 nm to 3 nm, and particularly preferably 0 nm to 2 nm. The retardation Rth(550) in the thickness direction is more preferably -5 nm to +5 nm, further preferably -3 nm to +3 nm, particularly preferably -2 nm to +2 nm. If the Re(550) and Rth(550) of the base film are in such ranges, adverse effects on display characteristics can be prevented when the optical laminate is applied to an image display device. In addition, Re(550) is the in-plane retardation of a film measured by the light of wavelength 550nm at 23 degreeC. Re(550) can be obtained by the formula: Re(550)=(nx−ny)×d. Rth(550) is the retardation in the thickness direction of the film measured at 23°C with light with a wavelength of 550 nm. Rth(550) can be obtained by the formula: Rth(550)=(nx−nz)×d. Here, the refractive index in the direction in which the refractive index in the nx system becomes the largest (that is, the direction of the slow axis), and the refractive index in the direction of the ny system in the direction orthogonal to the slow axis (that is, the direction of the advance axis), nz is the refractive index in the thickness direction, and d is the thickness (nm) of the film.

When the thickness of the base film is 40 μm, the light transmittance at 380 nm should be as high as possible. Specifically, the light transmittance is preferably 85% or more, more preferably 88% or more, and still more preferably 90% or more. If the light transmittance is in this range, the required transparency can be ensured. The light transmittance can be measured, for example, by a method according to ASTM-D-1003.

The lower the haze of the base film, the better. Specifically, the haze is preferably 5% or less, more preferably 3% or less, still more preferably 1.5% or less, and still more preferably 1% or less. When the haze is 5% or less, a favorable transparency can be imparted to the film. Furthermore, even when the optical layered body is used as a protective layer of a viewing-side polarizing plate of an image display device, the display content can be viewed favorably.

The YI (Yellowness Index, yellowness index) when the thickness of the base film is 40 μm is preferably 1.27 or less, more preferably 1.25 or less, still more preferably 1.23 or less, particularly preferably 1.20 or less. When YI exceeds 1.3, optical transparency may become insufficient. In addition, YI can be based on, for example, the tristimulus values (X, Y, Z) of the color obtained by measurement using a high-speed integrating sphere spectroscopic transmittance measuring machine (trade name DOT-3C: manufactured by Murakami Color Technology Laboratory), It is calculated|required by the following formula. YI=[(1.28X－1.06Z)/Y]×100

When the thickness of the base film is 40 μm, the b value (according to the scale of the hue of the Hunter color system) is preferably less than 1.5, more preferably 1.0 or less. In the case where the b value is 1.5 or more, an undesired color tone may occur. In addition, the b value can be measured, for example, by cutting a sample of the base film 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 Technology Laboratory), and measuring the color according to the Chinese The characteristic color system is obtained by evaluating the hue.

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

The tensile strength of the base film is preferably 10 MPa or more and less than 100 MPa, more preferably 30 MPa or more and less than 100 MPa. In the case where it is less than 10 MPa, there is a case where sufficient mechanical strength cannot be exhibited. If it exceeds 100 MPa, the workability may become insufficient. The tensile strength can be measured, for example, in accordance with ASTM-D-882-61T.

The tensile elongation of the base film is preferably 1.0% or more, more preferably 3.0% or more, and still more preferably 5.0% or more. The upper limit of the tensile elongation is, for example, 100%. When the tensile elongation rate is less than 1%, the toughness may become insufficient. The tensile elongation can be measured, for example, in accordance with ASTM-D-882-61T.

The tensile modulus of elasticity of the base film is preferably 0.5 GPa or more, more preferably 1 GPa or more, and still more preferably 2 GPa or more. The upper limit of the tensile elastic modulus is, for example, 20 GPa. When the tensile modulus of elasticity is less than 0.5 GPa, there are cases where sufficient mechanical strength cannot be exhibited. The tensile modulus of elasticity can be measured, for example, in accordance with ASTM-D-882-61T.

The base film may contain any suitable additives depending on the purpose. Specific examples of additives include: ultraviolet absorbers; antioxidants such as hindered phenols, phosphorus, and sulfur; stabilizers such as light-resistant stabilizers, weather-resistant stabilizers, and thermal stabilizers; reinforcing materials such as glass fibers and carbon fibers; Near-infrared absorbers; flame retardants such as tris(dibromopropyl) phosphate, triallyl phosphate, antimony oxide; antistatic agents such as anionic, cationic, and nonionic surfactants; inorganic pigments, organic Colorants such as pigments and dyes; organic fillers or inorganic fillers; resin modifiers; organic fillers or inorganic fillers; plasticizers; lubricants, etc. The additive may be added during the polymerization of the acrylic resin, or may be added during the film formation. The kind, quantity, combination, addition amount, etc. of the additives can be appropriately set depending on the purpose.

B-2. Acrylic resin B-2-1. Configuration of acrylic resin As the acrylic resin, any appropriate acrylic resin can be used. The acrylic resin typically contains an alkyl (meth)acrylate as a main component as a monomer unit. In this specification, "(meth)acrylic acid" means acrylic acid and/or methacrylic acid. As the alkyl (meth)acrylate constituting the main skeleton of the acrylic resin, a linear or branched alkyl group having 1 to 18 carbon atoms can be exemplified. These can be used alone or in combination. Furthermore, any appropriate comonomer may be introduced into the acrylic resin by copolymerization. The kind, amount, copolymerization ratio, and the like of such copolymerized monomers can be appropriately set depending on the purpose. The constituent components (monomer units) of the main skeleton of the acrylic resin will be described below with reference to the general formula (2).

The acrylic resin preferably 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 acrylic resin which has a lactone ring unit is described in Unexamined-Japanese-Patent No. 2008-181078, for example, and the description of this gazette is incorporated in this specification as a reference. The glutarimide unit is preferably represented by the following general formula (1):

[hua 1]

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

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

[hua 2]

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

The above-mentioned 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 above-mentioned acrylic resin is preferably 2 mol % to 50 mol %, more preferably 2 mol % to 45 mol %, and more preferably 2 mol % to 2 mol %. 40 mol %, preferably 2 mol % to 35 mol %, and most preferably 3 mol % to 30 mol %. If the content ratio is less than 2 mol%, the effects derived from the glutarimide unit (for example, higher optical properties, higher mechanical strength, and excellent polarizing elements may not be fully exhibited) Adhesion and thinning). If the content ratio exceeds 50 mol %, for example, heat resistance and transparency may become insufficient.

The above-mentioned acrylic resin may contain only a single (meth)acrylic acid alkyl ester unit, or may contain plural (meth)acrylic acid alkyl ester units in which R ⁴ and R ⁵ in the general formula (2) are different.

The content ratio of the alkyl (meth)acrylate unit in the above-mentioned acrylic resin is preferably 50 mol % to 98 mol %, more preferably 55 mol % to 98 mol %, and more preferably 60 mol % Ear% to 98 mol%, preferably 65 mol% to 98 mol%, and most preferably 70 mol% to 97 mol%. If the content ratio is less than 50 mol %, there is a possibility that the effects (for example, higher heat resistance and higher transparency) derived from the alkyl (meth)acrylate unit may not be sufficiently exhibited. If the above-mentioned content ratio exceeds 98 mol %, the resin becomes brittle and easily cracks, and high mechanical strength cannot be sufficiently exhibited, resulting in poor productivity.

The said acrylic resin may contain the unit other than a glutarimide unit and an alkyl (meth)acrylate unit.

In one embodiment, the acrylic resin may contain, for example, 0 to 10% by weight of unsaturated carboxylic acid units that do not participate in the intramolecular imidization reaction described below. 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 within 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 unit) other than the above. Examples of the other vinyl monomers include acrylonitrile, methacrylonitrile, ethacrylonitrile, allyl glycidyl ether, maleic anhydride, itaconic anhydride, and N-methylmaleic acid. Imide, N-ethylmaleimide, N-cyclohexylmaleimide, aminoethyl acrylate, propylaminoethyl acrylate, dimethylaminoethyl methacrylate Esters, ethylaminopropyl methacrylate, cyclohexylaminoethyl methacrylate, N-vinyldiethylamine, N-acetylvinylamine, allylamine, methallyl Amine, N-Methallylamine, 2-Isopropenyloxazoline, 2-Vinyloxazoline, 2-Propenyloxazoline, N-Phenylmaleimide, Methyl Phenylaminoethyl acrylate, styrene, α-methylstyrene, p-glycidyl styrene, p-aminostyrene, 2-styryl oxazoline, etc. These may be used alone or in combination. Preferred are styrene-based monomers such as styrene and α-methylstyrene. The content ratio 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 an undesired phase difference and the fall of transparency can be suppressed.

The imidization rate in the above-mentioned acrylic resin is preferably 2.5% to 20.0%. When the imidization ratio is in this range, a resin excellent in heat resistance, transparency, and moldability can be obtained, and the occurrence of scorch and reduction in mechanical strength during film forming can be prevented. In the said acrylic resin, the imidization rate is represented by the ratio of a glutarimide unit and an alkyl (meth)acrylate unit. The ratio can be obtained from, for example, an NMR (nuclear magnetic resonance, nuclear magnetic resonance) spectrum, an IR (infrared, infrared) spectrum of the acrylic resin, and the like. In the present embodiment, the imidization rate can be determined by ¹ H-NMR measurement of resin using ¹ HNMR BRUKER AvanceIII (400 MHz). More specifically, let the peak area of the O-CH ₃ proton derived from alkyl (meth)acrylate in the vicinity of 3.5 to 3.8 ppm be A, and let the peak area of glutarimide derived in the vicinity of 3.0 to 3.3 ppm be A. The peak area of the N-CH ₃ proton is set as B, and is obtained by the following formula. Imidization rate Im(%)={B/(A+B)}×100

The acid value of the above-mentioned acrylic resin is preferably 0.10 mmol/g to 0.50 mmol/g. When the acid value is in such a range, a resin excellent in the balance of heat resistance, mechanical properties, and moldability can be obtained. If the acid value is too small, problems such as increase in cost due to use of a modifier for adjusting to a desired acid value, generation of gel-like substances due to residual modifier, and the like may occur. When the acid value is too large, foaming at the time of film formation (for example, at the time of melt extrusion) tends to easily occur, and the productivity of the formed product tends to decrease. Regarding the above-mentioned acrylic resin, the acid value is the content of the carboxylic acid unit and the carboxylic acid anhydride unit in the acrylic resin. In the present embodiment, the acid value can be calculated by, for example, the titration method described in WO2005/054311 or Japanese Patent Laid-Open No. 2005-23272.

The weight average molecular weight of the acrylic resin is preferably 1,000-2,000,000, more preferably 5,000-1,000,000, further preferably 10,000-500,000, particularly preferably 50,000-500,000, and most preferably 60,000-150,000. The weight average molecular weight can be determined in terms of polystyrene using, for example, a gel permeation chromatography (GPC system, manufactured by Tosoh). Furthermore, tetrahydrofuran can be used as a solvent.

The Tg (glass transition temperature) of the acrylic resin is preferably 110°C or higher, more preferably 115°C or higher, further preferably 120°C or higher, particularly preferably 125°C or higher, and most preferably 130°C or higher. When Tg is 110 degreeC or more, the polarizing plate containing the base material film obtained from such a resin tends to be excellent in durability. The upper limit 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 formability will be excellent.

B-2-2. Polymerization of acrylic resin The above acrylic resin can be produced, for example, by the following method. The method comprises: (1) combining the (meth)acrylic acid alkyl ester monomer corresponding to the (meth)acrylic acid alkyl ester unit represented by the general formula (2) with the unsaturated carboxylic acid monomer and/or its The precursor monomer is copolymerized to obtain the copolymer (a); and (II) the copolymer (a) is treated with an imidizing agent, whereby the alkyl (meth)acrylate in the copolymer (a) is carried out Intramolecular imidization reaction between the base ester monomer unit and the unsaturated carboxylic acid monomer and/or its precursor monomer unit, and the glutarimide unit represented by the general formula (1) is introduced into the copolymer middle.

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

As a method of treating the copolymer (a) with an imidizing agent, any appropriate method can be used. As a specific example, the method of using an extruder, and the method of using a batch-type reaction tank (pressure vessel) are mentioned. The method of using an extruder includes heating and melting the copolymer (a) using the extruder, and treating it with an imidizing agent. In this case, as the extruder, any appropriate extruder can be used. Specific examples include a uniaxial extruder, a biaxial extruder, and a multiaxial extruder. Any suitable batch-type reaction tank (pressure vessel) can be used in the method using the batch-type reaction tank (pressure vessel).

As the imidizing agent, any appropriate compound can be used as long as the glutarimide unit represented by the above-mentioned general formula (1) can be generated. Specific examples of the imidizing agent include amines containing aliphatic hydrocarbon groups such as methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, tert-butylamine, and n-hexylamine; aniline, Amines containing aromatic hydrocarbon groups such as benzylamine, toluidine, trichloroaniline; amines containing alicyclic hydrocarbon groups such as cyclohexylamine. Furthermore, for example, a urea-based compound which generates such an amine by heating can also be used. As a urea compound, urea, 1, 3- dimethyl urea, 1, 3- diethyl urea, and 1, 3- dipropyl urea are mentioned, for example. The imidizing agent is preferably methylamine, ammonia, and cyclohexylamine, more preferably methylamine.

In the imidization, in addition to the imidization agent described above, a ring-closure accelerator may also be added as required.

The usage-amount of the imidizing agent in the imidization is preferably 0.5 to 10 parts by weight, more preferably 0.5 to 6 parts by weight relative to 100 parts by weight of the copolymer (a). If the usage-amount of the imidization agent is less than 0.5 parts by weight, there are many cases where the desired imidization rate is not achieved. As a result, the heat resistance of the obtained resin becomes extremely insufficient, and appearance defects such as burnt after molding may be induced. If the amount of the imidizing agent used exceeds 10 parts by weight, the imidizing agent may remain in the resin, and the imidizing agent may induce appearance defects such as burnt after molding or foaming.

In addition to the above-mentioned imidization, the production method of the present embodiment may include, if necessary, a treatment with an esterification agent.

Examples of the esterification agent include dimethyl carbonate, 2,2-dimethoxypropane, dimethyl sulfoxide, triethyl orthoformate, trimethyl orthoacetate, trimethyl orthoformate, dicarbonate Phenyl ester, dimethyl sulfate, methyl tosylate, methyl triflate, methyl acetate, methanol, ethanol, methyl isocyanate, p-chlorophenyl isocyanate, dimethylcarbodiamide Imine, dimethyl tert-butyl silyl chloride, isopropenyl acetate, dimethyl urea, tetramethyl ammonium hydroxide, dimethyl diethoxy silane, tetra-n-butoxy silane, phosphorous acid Dimethyl (trimethylsilyl) ester, trimethyl phosphite, trimethyl phosphate, tricresyl phosphate, diazomethane, ethylene oxide, propylene oxide, cyclohexane oxide, 2- Ethylhexyl glycidyl ether, phenyl glycidyl ether, benzyl glycidyl ether. Among these, from the viewpoints of cost, reactivity, etc., dimethyl carbonate is preferred.

The addition amount of the esterification agent can be set so that the acid value of an acrylic resin may become a desired value.

B-2-3. Combination of other resins In the embodiment of the present invention, the above-mentioned acrylic resins may be used in combination with other resins. That is, the monomer components constituting the acrylic resin and the monomer components constituting other resins may be copolymerized, and the copolymer may be used for the film formation described in the following item B-4; the acrylic resin may also be mixed with other resins. A blend of resins is used for film formation. Examples of other resins include styrene-based resins, polyethylene, polypropylene, polyamide, polyphenylene sulfide, polyether ether ketone, polyester, polysiloxane, polyphenylene ether, polyacetal, and polyamide Other thermoplastic resins such as amine and polyetherimide; thermosetting resins such as phenolic resins, melamine-based resins, polyester-based resins, polysiloxane-based resins, and epoxy-based resins. The type and compounding amount of the resin to be used in combination are appropriately set depending on the purpose, the properties expected for the film to be obtained, and the like. For example, a styrene-based resin (preferably an acrylonitrile-styrene copolymer) can be used in combination as a retardation control agent.

When the acrylic resin is used together with other resins, the content of the acrylic resin in the blend of the acrylic resin and other resins is preferably 50% by weight to 100% by weight, more preferably 60% by weight to 100% 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.

B-3. Core-Shell Particles In the above-mentioned base film, the core-shell particles are preferably 3 to 50 parts by weight, more preferably 5 to 25 parts by weight relative to 100 parts by weight of the acrylic resin. parts by weight, more preferably 7 parts by weight to 15 parts by weight. As a result, the elution of the acrylic resin forming the base film into the surface treatment layer is accelerated, and as a result, a compatible layer with high uniformity between the acrylic resin and the composition constituting the surface treatment layer can be formed on the base film. . Thereby, the apparent damage of the base film due to the formation of the surface treatment layer on the base film can be suppressed. Furthermore, the adhesiveness of a base film and a surface treatment layer can be improved.

The core-shell type particle typically has a core containing a rubbery polymer, and a coating layer containing a glassy polymer and covering the core. The core-shell type particle has one or more layers containing a glassy polymer as the innermost layer or the middle layer.

The Tg of the rubber-like polymer constituting the core is preferably 20°C or lower, more preferably -60°C to 20°C, and still more preferably -60°C to 10°C. If the Tg of the rubbery polymer constituting the core exceeds 20° C., there is a possibility that the improvement of the mechanical strength of the acrylic resin will be insufficient. The 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 still more preferably 60°C to 130°C. When Tg of the glassy polymer which comprises a coating layer is lower than 50 degreeC, there exists a possibility that the heat resistance of an acrylic resin may fall.

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

In one embodiment, the core-shell particles dispersed in the acrylic resin may have a flat shape. Core-shell particles can be flattened by stretching as described in item B-4 below. The length/thickness ratio of the flattened core-shell particles is 7.0 or less. The length/thickness ratio is preferably 6.5 or less, more preferably 6.3 or less. On the other hand, the ratio of length/thickness is preferably 4.0 or more, more preferably 4.5 or more, and still more preferably 5.0 or more. In this specification, "length/thickness ratio" means the ratio of the representative length and thickness of the top view shape of a core-shell particle. Here, the so-called "representative length" refers to the diameter in the case of a circular shape in plan view, the long diameter in the case of an ellipse, and the length of the diagonal in the case of a rectangle or a polygon. This ratio can be calculated|required by the following procedure, for example. The film sections obtained were photographed using a transmission electron microscope (eg, accelerating voltage of 80 kV, RuO4 _- stained ultrathin sectioning), and the longer of the core-shell particles present in the obtained photographs (obtained close to 30 are selected in sequence from the cross-sections representing the length, and (average value of length)/(average value of thickness) are calculated, whereby the ratio can be obtained.

Details of the rubber-like polymer constituting the core of the core-shell particle, the glass-like polymer (hard polymer) constituting the coating layer, the polymerization method of these, and other structures are described in, for example, Japanese Patent Laid-Open No. 2016-33552 Gazette. The description of this gazette is incorporated in this specification as a reference.

B-4. Formation of base film The base film according to the embodiment of the present invention can be represented by including the above-mentioned acrylic resin (in the case of using other resin in combination, it is a blend with the other resin) And the composition of the core-shell particle is formed by the method of forming a film. Further, the method of forming the substrate film may include extending the above-described film.

The average particle diameter of the core-shell particles used for film formation is preferably 1 nm to 500 nm. The average particle size of the core is preferably 50 nm to 300 nm, more preferably 70 nm to 300 nm.

As a method of forming the film, any appropriate method can be adopted. Specific examples include casting coating method (eg, casting method), extrusion molding method, injection molding method, compression molding method, transfer molding method, blow molding method, powder molding method, FRP (Fiber Reinforced) Plastic, fiber reinforced plastic) forming method, calendering method, hot pressing method. The extrusion molding method or the casting coating method is preferable. The reason is that the smoothness of the obtained film can be improved, and good optical uniformity can be obtained. Particularly preferred is the extrusion molding method. The reason for this is that there is no need to consider the problem caused by the residual solvent. Among them, the extrusion molding method using a T-die is preferable from the viewpoint of the productivity of the film and the ease of the subsequent stretching process. The molding conditions can be appropriately set according to the composition and type of the resin to be used, the desired properties of the film to be obtained, and the like.

As the stretching method, any suitable stretching method and stretching conditions (eg, stretching temperature, stretching ratio, stretching speed, stretching direction) can be adopted. Specific examples of the stretching method include free-end stretching, fixed-end stretching, free-end shrinking, and fixed-end shrinking. These may be used individually, may be used simultaneously, or may be used sequentially. The elution of the acrylic resin to the surface treatment layer is accelerated by extending the film in which the amount of the core-shell particles to the acrylic resin has been appropriately adjusted under suitable stretching conditions. As a result, the substrate film can be A compatible layer with high uniformity between the acrylic resin and the composition constituting the surface treatment layer is formed thereon.

The extending direction may be an appropriate direction depending on the purpose. Specifically, a longitudinal direction, a width direction, a thickness direction, and an oblique direction are mentioned. The extension direction may be one direction (uniaxial extension), two directions (biaxial extension), or three or more directions. In the embodiment of the present invention, typically, uniaxial stretching in the longitudinal direction, simultaneous biaxial stretching in the longitudinal and width directions, and sequential biaxial stretching in the longitudinal and width directions can be employed. Biaxial extension (simultaneous or sequential) is preferred. The reason for this is that it is easy to control the in-plane retardation and to realize optical isotropy.

The stretching temperature can be determined according to the expected optical properties, mechanical properties and thickness of the base film, the type of resin used, the thickness of the film used, the stretching method (uniaxial stretching or biaxial stretching), the stretching ratio, and the stretching speed. etc. to change. 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 extending at such a temperature, a base film having suitable properties can be obtained. The specific stretching temperature is, for example, 110°C to 200°C, preferably 120°C to 190°C. When the stretching temperature is in such a range, by appropriately adjusting the stretching ratio and the stretching speed, the elution of the acrylic resin to the surface treatment layer is accelerated, and as a result, the acrylic resin can be formed on the base film and the surface treatment can be formed. A compatible layer with higher composition uniformity of the layer.

In addition, the stretching ratio, like the stretching temperature, can vary depending on the optical properties, mechanical properties and thickness, the type of resin used, the thickness of the film used, the stretching method (uniaxial stretching or biaxial stretching), the stretching temperature, the stretching speed, etc. In the case of biaxial stretching, the ratio (TD/MD) of the stretching ratio in the width direction (TD) to the stretching ratio in the longitudinal direction (MD) is preferably 1.0-1.5, more preferably 1.0-1.4, and more preferably is 1.0 to 1.3. In addition, the area magnification (the product of the stretching magnification in the longitudinal direction and the stretching magnification in the width direction) in the case of biaxial stretching is preferably 2.0 to 6.0, more preferably 3.0 to 5.5, and still more preferably 3.5 to 5.2. If the stretching ratio is in such a range, by appropriately adjusting the stretching temperature and the stretching speed, the elution of the acrylic resin to the surface treatment layer is accelerated, and as a result, the acrylic resin can be formed on the base film and the surface treatment layer can be formed The composition has a higher homogeneity of the compatible layer.

In addition, the stretching speed, like the stretching temperature, may vary depending on the optical properties, mechanical properties and thickness, the type of resin used, the thickness of the film used, the stretching method (uniaxial stretching or biaxial stretching), the stretching temperature, the stretching magnification, etc. The extension speed is preferably 3%/sec to 20%/sec, more preferably 3%/sec to 15%/sec, and still more preferably 3%/sec to 10%/sec. In the case of biaxial extension, the extension speed in one direction and the extension speed in the other direction may be the same or different. When the stretching speed is in such a range, by appropriately adjusting the stretching temperature and the stretching ratio, the elution of the acrylic resin to the surface treatment layer is accelerated, and as a result, the acrylic resin can be formed on the base film and the surface treatment layer can be formed The composition has a higher homogeneity of the compatible layer.

The base film can be formed in the above-described manner.

C. Surface treatment layer The surface treatment layer is any appropriate functional layer formed on one side of the base film according to the function required for the optical laminate. As a specific example of a surface treatment layer, a hard-coat layer, an anti-glare layer, an antireflection layer, etc. are mentioned. The thickness of the surface treatment layer is preferably 3 μm to 20 μm, more preferably 5 μm to 15 μm.

The surface treatment layer is typically a hardened layer of the resin composition formed on the base film. The step of forming the surface treatment layer may include: coating the resin composition for forming the surface treatment layer on the base film to form a coating layer; and drying and curing the coating layer to form the surface treatment layer. Drying and hardening the coating layer may include heating the coating layer.

As a coating method of the resin composition, any appropriate method can be adopted. For example, bar coating method, roll coating method, gravure coating method, bar coating method, slot coating method, curtain coating method, spray coating method, corner coating method Wheel coating method. From the viewpoint of facilitating coating, the resin composition preferably contains a solvent for dilution.

The heating temperature of the coating layer can be set to any appropriate temperature corresponding to the composition of the resin composition, and it is preferably set to be equal to or lower than the glass transition temperature of the acrylic resin contained in the base film. When heating is performed at a temperature lower than or equal to the glass transition temperature of the acrylic resin contained in the base film, an optical laminate in which deformation due to heating is suppressed can be obtained. The heating temperature of the coating layer is, for example, 50°C to 140°C, preferably 60°C to 100°C. By heating at such a heating temperature, the optical laminated body excellent in the adhesiveness of a base film and a surface treatment layer can be obtained.

C-1. Hard coat layer The hard coat layer is a layer that imparts scratch resistance and chemical resistance to the surface of the base film. The hard coat layer has a hardness of preferably H or more, more preferably 3H or more in a pencil hardness test. The pencil hardness test can be measured according to JIS K 5400. The resin composition for forming a hard coat layer may contain, for example, a curable compound that can be cured by heat, light (ultraviolet rays, etc.), electron beams, or the like. Details of the hard coat layer and the resin composition for forming the hard coat layer are described in, for example, Japanese Patent Laid-Open No. 2014-240955. The entire description of this gazette is incorporated herein by reference.

C-2. Anti-glare layer The anti-glare layer is a layer for preventing reflection of external light by scattering and reflecting light. The resin composition for antiglare layer formation can contain, for example, a curable compound that can be cured by heat, light (ultraviolet rays, etc.), electron beams, or the like. The anti-glare layer typically has a fine concavo-convex shape on the surface. As a method of forming such a fine concavo-convex shape, for example, a method of containing fine particles in the above-mentioned curable compound can be mentioned. Details of the anti-glare layer and the resin composition for forming the anti-glare layer are described in, for example, Japanese Patent Laid-Open No. 2017-32711. The entire description of this gazette is incorporated herein by reference.

C-3. Anti-reflection layer The anti-reflection layer is used to prevent the reflection of external light. The resin composition for antireflection layer formation may contain, for example, a curable compound that can be cured by heat, light (ultraviolet rays, etc.), electron beams, or the like. The antireflection layer may be a single layer composed of only one layer, or may be a plurality of layers including two or more layers. Details of the antireflection layer and the resin composition for forming the antireflection layer are described in, for example, Japanese Patent Laid-Open No. 2012-155050. The entire description of this gazette is incorporated herein by reference.

D. Polarizing plate The optical laminates described in the above items A to C can be applied to polarizing plates. Therefore, the present invention also includes a polarizing plate using such an optical laminate. Typically, a polarizing plate has a polarizing element and the optical laminate of the present invention arranged on one side of the polarizing element. In the optical laminate system, the base film side is bonded to the polarizer, and can function as a protective layer of the polarizer.

As the polarizing element, any suitable polarizing element can be used. For example, the resin film forming the polarizing element may be a single-layer resin film, or may be a laminate of two or more layers.

Specific examples of polarizers including a single-layer resin film include hydrophilic polymers such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and ethylene-vinyl acetate copolymer-based partially saponified films. The film is obtained by dyeing and stretching treatment with dichroic substances such as iodine or dichroic dyes; polyene-based alignment films such as dehydration products of PVA or dehydrochlorination products of polyvinyl chloride, etc. In terms of excellent optical properties, it is preferable to use a polarizing element obtained by uniaxially extending a PVA-based film by dyeing with iodine.

The above-mentioned dyeing with iodine is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 to 7 times. The stretching may be carried out after the dyeing treatment, or may be carried out while dyeing. Moreover, you may dye it after extending|stretching. The PVA-based film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, and the like as necessary. For example, by immersing the PVA film in water and washing it before dyeing, not only the dirt and anti-blocking agent on the surface of the PVA film can be removed, but also the PVA film can be swelled to prevent uneven dyeing.

Specific examples of the polarizing element obtained by using the laminate include a laminate using a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a resin substrate and coating formed on A polarizing element obtained by a laminate of PVA-based resin layers of the resin substrate. A polarizing element obtained by using a laminate of a resin substrate and coating a PVA-based resin layer formed on the resin substrate can be produced, for example, by the following method: apply a PVA-based resin solution to a resin substrate, dry it, and A PVA-based resin layer is formed on the resin substrate to obtain a laminate of the resin substrate and the PVA-based resin layer; the laminate is stretched and dyed to form the PVA-based resin layer into a polarizer. In the present embodiment, the stretching typically involves immersing the layered body in a boric acid aqueous solution for stretching. Further, the stretching may further include performing in-air stretching of the laminate at a high temperature (eg, 95° C. or higher) before stretching in a boric acid aqueous solution, if necessary. The obtained laminate of resin substrate/polarizer can be used as it is (that is, the resin substrate can be used as a protective layer of the polarizer), or the resin substrate can be peeled off from the laminate of resin substrate/polarizer, Any suitable protective layer suitable for the purpose of the peeling area layer is used. The details of the manufacturing method of such a polarizing element are described in, for example, Japanese Patent Laid-Open No. 2012-73580. The entire description of this gazette is incorporated herein by reference.

The thickness of the polarizing element is, for example, 1 μm to 80 μm. In one embodiment, the thickness of the polarizing element is preferably 2 μm to 30 μm, and more preferably 3 μm to 25 μm.

E. Image Display Device The polarizing plate described in the above item D 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 adopts a well-known structure in the industry, so detailed description is omitted. Example

Hereinafter, the present invention will be specifically described with reference to examples, but the present invention is not limited to these examples. The measurement method of each characteristic is as follows. In addition, unless otherwise specified, "parts" and "%" in the examples are based on weight. (1) The ratio of the components of the acrylic resin eluted into the surface-treated layer The elution to the surface-treated layer was measured by a method using a three-dimensional optical refractive index/film thickness measuring device and a coupler (manufactured by Metricon, Metricon 2010/M). The ratio of the composition of the acrylic resin. The measurement of the refractive index using the halide coupler was carried out under the following conditions.・Measurement conditions Light source: 594 nm Mode: TE (transverse electric, transverse electric field) Scan: 300～-300 (1-1) Refractive index R1 of the substrate film Measurement type: Bulk/substrate ( Bulk/Substrate) is detected by the detection mode of the substrate film (called Knee). Let the refractive index obtained by measurement be R1. (1-2) Refractive index R2 of the surface treatment layer Measurement type: Single Film (Prism Couple) PET substrate (manufactured by Toray, trade name: U48-3, refractive index: 1.60) Except having set the heating temperature of the coating layer to 60° C. as a base film, in the same manner as in each example, a laminate having the same thickness as in each example was obtained. By measuring the laminate in the Single Film mode, a plurality of modes are detected. Let the refractive index obtained by measurement be R2. (1-3) Refractive index R3 at a depth of 3.0 μm in the direction of the surface treatment layer from the base film side Measurement type: Single Film (Prism Couple) Analysis method: Index gradient in the optical laminate In the case where the refractive index changes in the depth direction, the change in the refractive index with respect to the depth direction can be quantitatively obtained by using the above-mentioned method using a halide coupler. A plurality of modes are detected by the measurement of the optical laminate, and the change in refractive index with respect to the depth direction is calculated by the Index gradient analysis. Based on the following formula, "the position of the depth of 3.0 μm" in the direction of the surface treatment layer from the base film side was determined, and the obtained refractive index was set as R3. "Position at a depth of 3.0 μm" (position from the surface treatment side) = thickness of the surface treatment layer (thickness of the PET substrate hard coat layer) - (3 μm) (1-4) constitutes the surface treatment layer from the base film side The ratio X of the components of the acrylic resin eluted to the surface treatment layer among the components at the depth of 3.0 μm in the direction The components constituting the position of the depth of 3.0 μm in the direction of the surface treatment layer from the base film side were calculated according to the following formula. The ratio X (%) of the components of the acrylic resin eluted in the surface treatment layer. X(%)=(R3-R2)×100/(R1-R2) (2) Appearance evaluation Regarding the optical laminates obtained in the examples and comparative examples, poor appearance (derived from the formation on the base film) was visually confirmed The presence or absence of damage (defective appearance) is judged by the following indicators. ○: Damage marks are visually observed ×: No damage marks are visually observed (3) Adhesion evaluation The adhesion of the surface treatment layer to the base film was evaluated in accordance with the grid peeling test of JIS K-5400 (number of grids: 100) , judged by the following indicators. 〇: The number of grid peeling is 0 ×: The number of grid peeling is 1 or more

<Example 1> 1. Preparation of base film MS resin (MS-200; copolymer of methyl methacrylate/styrene (mol ratio) = 80/20, Nippon Steel Chemicals) was prepared using monomethylamine. Co., Ltd. product) imidization was performed (imidation rate: 5%). The obtained imidized MS resin has glutarimide units represented by the general formula (1) (R ¹ and R ³ are methyl groups, R ² is a hydrogen atom), and ( Meth)acrylate units (R ⁴ and R ⁵ are methyl groups), and styrene units. In addition, the above-mentioned imidization was carried out using a meshing type co-rotating twin-screw extruder with a diameter of 15 mm. The set temperature of each tempering zone of the extruder was set to 230° C., the screw speed was set to 150 rpm, and the MS resin was supplied at 2.0 kg/hr. The supply amount of monomethylamine was based on 100 parts by weight of the MS resin. 2 parts by weight. The MS resin was injected from the hopper, and after the resin was melted and filled by the kneading stage, monomethylamine was injected from the nozzle. A sealing ring was installed at the end of the reaction zone to fill the resin. The pressure of the exhaust port was reduced to -0.08 MPa to remove the by-products and excess methylamine after the reaction to remove volatiles. The resin discharged from the die set at the outlet of the extruder in the form of strands is cooled in a water tank, and then pelletized by 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 5 parts by weight of the core-shell particles were put into a uniaxial extruder, melt-mixed, and film-formed through a T-die to obtain an extruded film. The obtained extruded film was simultaneously biaxially stretched by 2 times in the longitudinal direction and the width direction at a stretching temperature of 140°C. The extension speed was 10%/sec in both the longitudinal direction and the width direction. Thus, a base film A having a thickness of 30 μm was produced. 2. Fabrication of the optical laminate In such a way that the thickness after curing becomes 6 μm, a UV curable resin (4-HBA (4-hydroxybutyl acrylate, 4-hydroxybutyl acrylate) is coated on one side of the above-mentioned base film A. ) (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 16 parts by weight, NK oligo UA-53H-80BK (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.) 32 parts by weight, Viscoat #300 (manufactured by Osaka Organic Chemical Industry Co., Ltd.) 48 parts by weight, 4 parts by weight of A-GLY-9E (manufactured by Shin-Nakamura Chemical Industry Co., Ltd.), and 2.4 parts by weight of IRGACURE 907 (manufactured by BASF) were mixed with MIBK (methyl isobutyl ketone, methyl isobutyl ketone). ketone): PGM (Propylene glycol monomethyl ether, propylene glycol monomethyl ether) = 50:50 solvent diluted so that the solid content concentration becomes 42.0%) to form a coating layer. Then, the said coating layer was dried at 70 degreeC, and UV hardening was performed, and the optical laminated body 1 which formed the hard-coat layer on one side of the base film A was obtained. The above-mentioned optical layered body 1 was used for each evaluation. The results are shown in Table 1.

<Example 2> 1. Preparation of base film The same procedure as in Example 1 was carried out, except that the blending amount of the core-shell particles was set to 10 parts by weight, and the stretching temperature of the extruded film was set to 150° C. The base film B was produced in the same manner. 2. Production of optical laminate An optical laminate 2 having a hard coat layer formed on one side of the substrate film B was obtained in the same manner as in Example 1, except that the above-mentioned base film B was used. The above-mentioned optical layered body 2 was used for each evaluation. The results are shown in Table 1.

<Example 3> 1. Preparation of base film The same procedure as in Example 1 was carried out, except that the blending amount of the core-shell particles was set to 10 parts by weight, and the stretching temperature of the extruded film was set to 160° C. The base film C was produced by the method. 2. Production of optical laminate An optical laminate 3 having a hard coat layer formed on one side of the substrate film C was obtained in the same manner as in Example 1, except that the aforementioned base film C was used. The above-mentioned optical layered body 3 was used for each evaluation. The results are shown in Table 1.

<Example 4> 1. Preparation of base film The same procedure as in Example 1 was carried out, except that the blending amount of the core-shell particles was 13 parts by weight, and the stretching temperature of the extruded film was 152° C. The base film D was produced by the method. 2. Preparation of optical layered body An optical layered body 4 having a hard coat layer formed on one side of the substrate film D was obtained in the same manner as in Example 1, except that the above-mentioned base film D was used. The above-mentioned optical layered body 4 was used for each evaluation. The results are shown in Table 1.

<Example 5> 1. Preparation of base film 100 parts by weight of the imidized MS resin obtained above and 15 parts by weight of core-shell particles were put into a uniaxial extruder, melt-mixed, and passed through a T-die. A film is formed, whereby an extruded film is obtained. The obtained extruded film was simultaneously biaxially stretched by 2 times in the longitudinal direction and the width direction at a stretching temperature of 152°C. The extension speed was 10%/sec in both the longitudinal direction and the width direction. Thus, a base film E having a thickness of 40 μm was produced. 2. Preparation of Optical Laminated Body An optical layered body 5 having a hard coat layer formed on one side of the base film E was obtained in the same manner as in Example 1 except that the above-described base film E was used. The above-mentioned optical layered body 5 was used for each evaluation. The results are shown in Table 1.

<Example 6> 1. Preparation of base film The same procedure as in Example 1 was carried out, except that the blending amount of the core-shell particles was 23 parts by weight, and the stretching temperature of the extruded film was 137° C. The base film F was produced by the method. 2. Production of optical laminate An optical laminate 6 having a hard coat layer formed on one side of the base film F was obtained in the same manner as in Example 1, except that the above-mentioned base film F was used. The above-mentioned optical layered body 6 was used for each evaluation. The results are shown in Table 1.

<Example 7> 1. Preparation of base film 100 parts by weight of the imidized MS resin obtained above and 23 parts by weight of core-shell particles were put into a uniaxial extruder, melt-mixed, and passed through a T-die. A film is formed, whereby an extruded film is obtained. The obtained extruded film was simultaneously biaxially stretched by 2 times in the longitudinal direction and the width direction at a stretching temperature of 152°C. The extension speed was 10%/sec in both the longitudinal direction and the width direction. Thus, a base film G with a thickness of 20 μm was produced. 2. Production of optical laminate An optical laminate 7 in which a hard coat layer was formed on one side of the substrate film G was obtained in the same manner as in Example 1, except that the aforementioned base film G was used. The above-mentioned optical layered body 7 was used for each evaluation. The results are shown in Table 1.

<Example 8> 1. Preparation of base film The same procedure as in Example 1 was carried out, except that the blending amount of the core-shell particles was set to 10 parts by weight, and the stretching temperature of the extruded film was set to 160° C. The base film H was produced by the method. 2. Preparation of Optical Layered Product A hard coat was formed on one side of the base film H in the same manner as in Example 1, except that the base film H was used and the film thickness after drying was set to 15 μm. Optical laminate 8 of layers. The above-mentioned optical layered body 8 was used for each evaluation. The results are shown in Table 1.

<Comparative Example 1> 1. Preparation of base film An extruded film was obtained by injecting the imidized MS resin obtained above into a uniaxial extruder, melt mixing, and film formation through a T die. The obtained extruded film was simultaneously biaxially stretched by 2 times in the longitudinal direction and the width direction at a stretching temperature of 130°C. The extension speed was 10%/sec in both the longitudinal direction and the width direction. Thus, the base film I with a thickness of 40 μm was produced. 2. Preparation of Optical Laminated Body An optical layered body 9 having a hard coat layer formed on one side of the base film 1 was obtained in the same manner as in Example 1, except that the above-mentioned base film 1 was used. The above-mentioned optical layered body 9 was used for each evaluation. The results are shown in Table 1.

<Comparative example 2> 1. Production of base film A base film J was produced in the same manner as in Example 1, except that the core-shell particles were not prepared. 2. Production of Optical Laminated Body An optical layered body 10 having a hard coat layer formed on one side of the base film J was obtained in the same manner as in Example 1 except that the above-described base film J was used. The above-mentioned optical layered body 10 was used for each evaluation. The results are shown in Table 1.

<Comparative Example 3> 1. Production of base film A base film K was produced in the same manner as in Example 1, except that the core-shell particles were not prepared and the stretching temperature of the extruded film was set to 160°C. 2. Production of optical laminate An optical laminate 11 having a hard coat layer formed on one side of the substrate film K was obtained in the same manner as in Example 1, except that the aforementioned base film K was used. The above-mentioned optical layered body 11 was used for each evaluation. The results are shown in Table 1.

[Table 1]

As can be seen from Table 1, the ratio of the components of the acrylic resin eluted to the surface treatment layer in the components constituting the position at a depth of 3.0 μm in the surface treatment layer direction from the base film side was 18% or more. The optical laminates of Examples 1 to 8 were excellent in appearance and adhesiveness. [Industrial Availability]

The optical laminate of the present invention can be suitably used as a protective layer of a polarizing element. The polarizing plate which has the optical laminated body of this invention as a protective layer can be used suitably for an image display apparatus. The image display device as described above can be used for portable devices such as portable information terminals (PDAs), smart phones, mobile phones, clocks, digital cameras, and portable game consoles; computer monitors, notebook computers, etc. OA equipment such as photocopiers; home electrical equipment such as camcorders, televisions, microwave ovens; rear monitors, monitors for car navigation systems, car audio and other in-vehicle equipment; digital signage, information displays for commercial stores, etc. Equipment; security equipment such as monitoring monitors; nursing care and medical equipment such as nursing care monitors and medical monitors.

10‧‧‧Substrate film20‧‧‧Surface treatment layer100‧‧‧Optical laminate

FIG. 1 is a schematic cross-sectional view of an optical laminate according to an embodiment of the present invention.

10‧‧‧Substrate film

20‧‧‧Surface treatment layer

100‧‧‧Optical Laminate

Claims (10)

An optical laminate comprising a base film containing an acrylic resin, and a surface treatment layer formed on one side of the base film, and having a depth of 3.0 μm in the direction of the surface treatment layer from the base film side The ratio of the component of the said acrylic resin eluted to the said surface treatment layer among the components of the position is 18% or more. The optical laminate according to claim 1, wherein the refractive index of the base film is R1, the refractive index of the surface treatment layer is R2, and the direction of the surface treatment layer from the base film side is When the refractive index of the position with a depth of 3.0 μm is set to R3, R3≦0.18R1+0.82R2 (wherein, R1<R2) is satisfied. The optical laminate according to claim 1 or 2, wherein the thickness of the surface treatment layer is 3 μm to 20 μm. The optical laminate according to claim 1 or 2, wherein the base film contains the acrylic resin and core-shell particles dispersed in the acrylic resin. The optical laminate according to claim 4, wherein the base film contains 3 parts by weight to 50 parts by weight of the core-shell particles with respect to 100 parts by weight of the acrylic resin. The optical laminate according to claim 1 or 2, wherein the above-mentioned acrylic resin has a compound selected from the group consisting of pentyl At least one of the group consisting of diimide unit, lactone ring unit, maleic anhydride unit, maleimide unit and glutaric anhydride unit. The optical laminate according to claim 1 or 2, wherein the surface treatment layer is a hardened layer of a resin coated on the base film. The optical laminate according to claim 1 or 2, wherein the surface treatment layer is at least one selected from the group consisting of a hard coat layer, an antiglare layer, and an antireflection layer. A polarizing plate comprising a polarizing element and a protective layer disposed on one side of the polarizing element, wherein the protective layer is the optical laminate according to any one of claims 1 to 8. An image display device including the polarizing plate as claimed in claim 9.

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