WO2018190175A1

WO2018190175A1 - Optical laminate, polarizing plate, and image display device

Info

Publication number: WO2018190175A1
Application number: PCT/JP2018/014124
Authority: WO
Inventors: 慎哉平岡; 岸　敦史; 友徳上野; 佑輔茂手木
Original assignee: 日東電工株式会社
Priority date: 2017-04-10
Filing date: 2018-04-02
Publication date: 2018-10-18
Also published as: JP7083814B2; KR102510766B1; JPWO2018190175A1; TW201842359A; CN110520765B; KR20190137805A; TWI771403B; CN110520765A

Abstract

Provided is an optical laminate to which a function of a surface treatment layer has been sufficiently imparted. This optical laminate includes a substrate film and a surface treatment layer that is formed on one side of the substrate film, wherein the substrate film includes an acrylic resin and core-shell particles that are dispersed in the acrylic resin, the elastic modulus of the substrate film is 4.0GPa or greater, and among components that make up a position at a depth of 3.0μm from a substrate film side in the direction of the surface treatment layer, the proportion of acrylic resin components that have migrated into the surface treatment layer is less than 20%.

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, an optical laminate in which a functional layer (surface treatment layer) such as a hard coat layer, an antiglare layer, or an antireflection layer is formed on one side of a base film made of an acrylic resin is known (Patent Document 1). ). Such an optical laminate can be used, for example, as a protective film for a polarizer or a front plate of an image display device.

JP 2016-218478 A

However, the conventional optical layered body as described above may not be sufficiently provided with the function of the surface treatment layer.

The present invention has been made in order to solve the above-described conventional problems, and the main purpose thereof is an optical laminate having a sufficient function of a surface treatment layer, a polarizing plate provided with such an optical laminate, And it is providing the image display apparatus provided with such a polarizing plate.

The optical layered body of the present invention includes a base film and a surface treatment layer formed on one side of the base film, and the base film is dispersed in the acrylic resin and the acrylic resin. A core-shell type particle, wherein the base film has an elastic modulus of 4.0 GPa or more, and constitutes a position having a depth of 3.0 μm in the direction of the surface treatment layer from the base film side The proportion of the acrylic resin component eluted in the surface treatment layer is less than 20%.
In one embodiment, when the refractive index of the base film is R1, and the refractive index at a depth of 3.0 μm in the direction of the surface treatment layer from the base film side is R3, R3> 0.2R1 + 0.8R2 (where R1 <R2) is satisfied.
In one embodiment, the surface treatment layer has a thickness of 3 μm to 20 μm.
In one embodiment, the base film contains 5 to 20 parts by weight of the core-shell type particles with respect to 100 parts by weight of the acrylic resin.
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 surface treatment layer is a cured layer of resin applied 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 antiglare layer, and an antireflection layer.
According to another aspect of the present invention, a polarizing plate is provided. The polarizing plate includes a polarizer and a protective layer disposed on one side of the polarizer, and the protective layer is the optical laminate.
According to another aspect of the present invention, an image display device is provided. The image display device includes the polarizing plate.

According to the present invention, the elastic modulus of the base film is 4.0 GPa or more, and among the components constituting the depth of 3.0 μm in the direction of the surface treatment layer from the base film side, the surface treatment layer An optical laminate in which the function of the surface treatment layer is sufficiently imparted by the eluted acrylic resin component being less than 20%, a polarizing plate provided with such an optical laminate, and such a polarizing plate Can be provided.

It is a schematic sectional drawing of the optical laminated body by one Embodiment of this invention.

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

A. FIG. 1 is a schematic cross-sectional view of an optical laminate according to one 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. The base film 10 includes an acrylic resin and core-shell type particles dispersed in the acrylic resin. The elastic modulus of the base film 10 is 4.0 GPa or more. The ratio of the component of the acrylic resin eluted to the surface treatment layer among 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 is less than 20%. The position at a depth of 3.0 μm in the direction of the surface treatment layer from the base film side is typically 3.0 μm away from the interface with the surface treatment layer of the base film in the direction of the surface treatment layer. It is the position. The proportion of the acrylic resin component at the “position of 3 μm depth” is typically derived by the following method.
Calculation position of acrylic resin component (position from the surface treatment side) = surface treatment layer thickness (PET base material hard coat thickness) − (3 μm)
For example, when (PET base material hard coat thickness) is 15 μm, the ratio of the acrylic resin component at the 12 μm position from the surface treatment side is measured. The surface treatment layer thickness (hard coat thickness) is typically derived by the following procedure. First, a PET base material (trade name: U48-3, refractive index: 1.60) manufactured by Toray Industries, Inc. was used as the base film, and the coating layer was heated at 70 ° C. and UV cured. Then, an optical laminate having a hard coat layer formed thereon is obtained. A black acrylic plate (Mitsubishi Rayon Co., Ltd., thickness 2 mm) was attached to the base layer side of the obtained optical laminate through an acrylic adhesive having a thickness of 20 μm. Next, the reflection spectrum of the hard coat layer is measured under the following conditions using an instantaneous multi-photometry system (trade name: MCPD3700, manufactured by Otsuka Electronics Co., Ltd.). Since the composition for forming a hard coat layer does not penetrate into the PET substrate used in these laminates, the thickness of only the hard coat layer is measured from the peak position of the FFT spectrum obtained from the laminate.
Reflection spectrum measurement conditions Reference: Mirror Algorithm: FFT method Calculation wavelength: 450 nm to 850 nm
・ Detection conditions Exposure time: 20 ms
Lamp gain: Normal Integration count: 10 times / FFT method Film thickness range: 2 to 15 μm
Film thickness resolution: 24nm

When the ratio is 20% or more, the function of the surface treatment layer (typically scratch resistance when the surface treatment layer is a hard coat layer) may not be sufficiently provided, and the base film and the surface Adhesiveness with a processing layer may fall. The proportion of the acrylic resin component eluted in the surface treatment layer out of the components constituting the depth of 3.0 μm in the direction of the surface treatment layer 20 from the base film 10 side is measured by, for example, the prism coupler method. be able to. Specifically, the refractive index of the base film is R1, the refractive index of the surface treatment layer is R2, and a depth of 3.0 μm from the base film side measured by the prism coupler method to the surface treatment layer. When the refractive index at the position is R3, the ratio X of the component of the acrylic resin eluted in the surface treatment layer among the components constituting the depth of 3.0 μm from the base film side to the surface treatment layer ( %) Is expressed by the following equation.
X (%) = (R3-R2) × 100 / (R1-R2)
Therefore, the optical laminate 100 has a refractive index R1 of the base film, a refractive index R2 of the surface treatment layer, and a refractive index R3 at a depth of 3.0 μm from the base film side to the surface treatment layer. Preferably the following inequality is satisfied.
R3> 0.2R1 + 0.8R2 (R1 <R2)
The thickness of the surface treatment layer is preferably 3 μm to 20 μm, more preferably 5 μm to 15 μm. The base film 10 preferably contains 5 to 20 parts by weight of core-shell type 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 cured layer of a resin composition applied 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 antiglare layer, and an antireflection layer. According to the optical laminate 100, the amount of the acrylic resin contained in the base film 10 to the surface treatment layer 20 is sufficiently small. Thereby, the fall of the functionality of a surface treatment layer by the acrylic resin eluting to the surface treatment layer 20 can be suppressed. Specifically, when the surface treatment layer is a hard coat layer, a decrease in scratch resistance of the hard coat layer can be suppressed, and when the surface treatment layer is an antiglare layer, the antiglare layer can be prevented. A decrease in glare can be suppressed, and when the surface treatment layer is an antireflection layer, a decrease in antireflection properties of the antireflection layer can be suppressed. Further, the adhesion between 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 includes an acrylic resin and core-shell type particles dispersed in the acrylic resin as described above. The thickness of the base film is preferably 5 μm to 150 μm, more preferably 10 μm to 100 μm. As described above, the elastic modulus of the base film is 4.0 GPa or more. In the base film, when a surface treatment layer described later is formed, the acrylic resin can be eluted into the surface treatment layer. The ratio of the component of the acrylic resin is less than 20% among the components constituting the position having a depth of 3.0 μm in the direction of the surface treatment layer from the base film side.

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. Say something. The in-plane retardation Re (550) is more preferably 0 nm to 5 nm, further preferably 0 nm to 3 nm, and particularly preferably 0 nm to 2 nm. 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 base film are within such ranges, adverse effects on display characteristics can be prevented when the optical laminate 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 light transmittance at 380 nm when the thickness of the substrate film is 40 μm is preferably as high as possible. 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 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 particularly preferably 1% or less. When the haze is 5% or less, the film can have a good clear feeling. Furthermore, even when the optical layered body is used as a protective layer for the viewing-side polarizing plate of the image display device, the display content can be visually recognized well.

YI at a thickness of 40 μm of the base film is preferably 1.27 or less, more preferably 1.25 or less, further 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 40 μm of the substrate 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 base film sample into a 3 cm square and 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 base 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. And most preferably 100 g / m ² · 24 hr or less. When the moisture permeability of the base film is within such a range, a polarizing plate excellent in durability and moisture resistance can be obtained when used as a protective layer for a polarizer.

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. 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 base 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 according to, for example, ASTM-D-882-61T.

The tensile elastic modulus of the base film is 4 GPa or more, preferably 4.5 GPa or more. The upper limit of the tensile modulus is, for example, 20 GPa. The tensile elastic modulus can be measured, for example, according to ASTM-D-882-61T.

The base 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 coloring agents such as dyes; organic fillers or inorganic fillers; resin modifiers; organic fillers and inorganic fillers; plasticizers; 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.

B-2. Acrylic resin B-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 of the publication is incorporated herein by reference. The glutarimide unit is preferably represented by the following general formula (1):

In the general formula (1), R ¹ and R ² each independently represents 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, carbon A cycloalkyl group having 3 to 12 carbon atoms or an aryl group having 6 to 10 carbon atoms is shown. In the general formula (1), preferably, 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 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, the acrylic resin can contain, for example, 0 to 10% by weight of an unsaturated carboxylic acid unit that is not involved in the intramolecular imidation reaction described later. 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 copolymerizable vinyl monomer units (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, 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 imidization 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 the resin using ¹ H NMR 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, further 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 base film obtained from such resin will become easily 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.

B-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 imidization, 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 production method of the present embodiment can include treatment with an esterifying agent in addition to the imidization as necessary.

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 trifluoromethane sulfonate, Methyl acetate, methanol, ethanol, methyl isocyanate, p-chlorophenyl isocyanate, dimethylcarbodiimide, dimethyl-t-butylsilyl chloride, isopropenyl acetate, dimethylurea, tetramethylammonium hydroxide, dimethyldiethoxysilane, tetra-N-butoxysilane , 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.

B-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, a monomer component constituting an acrylic resin and a monomer component constituting another resin may be copolymerized, and the copolymer may be used for film formation described later in Section B-4; A blend with the resin 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 phase difference controlling agent.

When the acrylic resin and another resin are used in combination, the content of the acrylic resin in the blend of the acrylic resin and the other resin 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 type particles In the above base film, the core-shell type particles are preferably blended in an amount of 5 to 20 parts by weight, more preferably 5 to 13 parts by weight with respect to 100 parts by weight of the acrylic resin. Thereby, while having a desired elasticity modulus, the base film in which the elution to the surface treatment layer of acrylic resin was suppressed can be obtained. As a result, a decrease in functionality of the surface treatment layer when the surface treatment layer is formed on the base film can be suppressed, and the adhesion between the base film and the surface treatment layer can be improved.

The core-shell type particles typically have a core made of a rubber-like polymer and a coating layer made of a glassy 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. 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 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% 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% 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 particle 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 B-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.

B-4. Formation of Base Film A base film according to an embodiment of the present invention typically includes the above acrylic resin (in the case of using another resin in combination, a blend with the other resin) and core-shell type particles. It can be formed by a method comprising filming the composition. Further, the method of forming the base 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. 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.

As the stretching method, any appropriate stretching method and stretching conditions (for example, 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 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 the core-shell type particles with respect to the acrylic resin is appropriately adjusted under appropriate stretching conditions, the film has a desired elastic modulus, and elution of the acrylic resin into the surface treatment layer is suppressed. A substrate film can be obtained. As a result, a decrease in functionality of the surface treatment layer when the surface treatment layer is formed on the base film can be suppressed, and the adhesion between the base film and the surface treatment layer can be improved.

The stretching direction can be an appropriate direction 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 base film, type of resin used, film thickness used, stretching method (uniaxial stretching or biaxial stretching), stretch ratio, stretch It can vary depending on speed and 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 extending | stretching at such temperature, the base film which has a suitable characteristic may 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, a base film having a desired elastic modulus and suppressing elution of the acrylic resin into the surface treatment layer is obtained. Can be obtained. As a result, a decrease in functionality of the surface treatment layer when the surface treatment layer is formed on the base film can be suppressed, and the adhesion between the base film and the surface treatment layer can be improved.

The stretching ratio is also the same as the stretching temperature: optical properties, mechanical properties and thickness, type of resin used, film thickness used, stretching method (uniaxial stretching or biaxial stretching), stretching temperature, stretching It can vary depending on speed and the like. When biaxial stretching is employed, 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. In addition, the plane magnification (product of the draw ratio in the length direction and the draw ratio in the width direction) when 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, by appropriately adjusting the drawing temperature and the drawing speed, a base film having a desired elastic modulus and suppressing elution of the acrylic resin into the surface treatment layer is obtained. Can be obtained. As a result, a decrease in functionality of the surface treatment layer when the surface treatment layer is formed on the base film can be suppressed, and the adhesion between the base film and the surface treatment layer can be improved.

Stretching speed is also the same as stretching temperature: optical properties, mechanical properties and thickness, type of resin used, film thickness used, stretching method (uniaxial stretching or biaxial stretching), stretching temperature, stretching It can change depending on the magnification or 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. If the stretching speed is in such a range, by appropriately adjusting the stretching temperature and the stretching ratio, a base film having a desired elastic modulus and suppressing elution of the acrylic resin into the surface treatment layer is obtained. Can be obtained. As a result, a decrease in functionality of the surface treatment layer when the surface treatment layer is formed on the base film can be suppressed, and the adhesion between the base film and the surface treatment layer can be improved.

As described above, the base film can be formed.

C. Surface treatment layer The surface treatment layer is any suitable functional layer formed on one side of the base film according to the function required for the optical laminate. Specific examples of the surface treatment layer include a hard coat layer, an antiglare layer, and an antireflection layer. 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 cured layer of the resin composition formed on the base film. The step of forming the surface treatment layer includes forming a coating layer by applying a resin composition for forming the surface treatment layer on the base film, and drying and curing the coating layer to form a surface treatment layer. Can be included. Drying and curing the coating layer can include heating the coating layer.

Any appropriate method can be adopted as a method for applying the resin composition. Examples thereof include a bar coating method, a roll coating method, a gravure coating method, a rod coating method, a slot orifice coating method, a curtain coating method, a fountain coating method, and a comma coating method. From the viewpoint of facilitating application, the resin composition preferably contains a solvent for dilution.

The heating temperature of the coating layer can be set to any appropriate temperature according to the composition of the resin composition, and is preferably set to be equal to or lower than the glass transition temperature of the acrylic resin contained in the base film. If heating is performed at a temperature not higher than 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, an optical laminate excellent in adhesion between the base film and the surface treatment layer can be obtained.

C-1. Hard coat layer The hard coat layer is a layer that imparts scratch resistance, chemical resistance, and the like to the surface of the substrate film. The hard coat layer preferably has a hardness of H or higher, more preferably 3H or higher, in a pencil hardness test. The pencil hardness test can be measured according to JIS K 5400. The resin composition for forming the hard coat layer may contain, for example, a curable compound that can be cured by heat, light (such as ultraviolet rays), or an electron beam. Details of the hard coat layer and the resin composition for forming the hard coat layer are described in, for example, JP-A-2014-240955. This publication is incorporated herein by reference in its entirety.

C-2. Antiglare layer The antiglare layer is a layer for preventing reflection of external light by scattering and reflecting light. The resin composition for forming an antiglare layer can contain, for example, a curable compound that can be cured by heat, light (such as ultraviolet rays), or an electron beam. The antiglare layer typically has a fine uneven shape on the surface. Examples of a method for forming such a fine concavo-convex shape include a method in which fine particles are contained in the curable compound. Details of the antiglare layer and the resin composition for forming the antiglare layer are described in, for example, JP-A-2017-32711. This publication is incorporated herein by reference in its entirety.

C-3. Antireflection layer The antireflection layer is a layer for preventing reflection of external light. The resin composition for forming the antireflection layer can contain, for example, a curable compound that can be cured by heat, light (such as ultraviolet rays), or an electron beam. The antireflection layer may be a single layer composed of only one layer or a plurality of layers composed of two or more layers. Details of the antireflection layer and the resin composition for forming the antireflection layer are described in, for example, JP-A-2012-155050. This publication is incorporated herein by reference in its entirety.

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

Any appropriate polarizer can 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 aqueous iodine 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. Furthermore, 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 aqueous boric acid 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 2 μm to 30 μm, more preferably 3 μm to 25 μm.

E. Image Display Device The polarizing plate described in the above section 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. Since the image display apparatus employs a configuration well known in the industry, detailed description thereof is omitted.

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) Ratio of components of acrylic resin eluted in surface treatment layer Acrylic resin eluted in surface treatment layer by a method using a three-dimensional photorefractive index / film thickness measuring device prism coupler (Metricon, Metricon 2010 / M) The proportion of resin components was measured. The refractive index measurement using a prism coupler was performed under the following conditions.
Measurement condition light source: 594 nm
Mode: TE
Scan: 300 to -300
(1-1) Refractive index R1 of base film
Measurement type: Bulk / Substrate
The mode (called Knee) was detected by measuring the substrate film. The refractive index obtained by the measurement was R1.
(1-2) Refractive index R2 of the surface treatment layer
Measurement type: Single Film (Prism Couple)
Except that a PET substrate (trade name: U48-3, refractive index: 1.60) manufactured by Toray Industries, Inc. was used as the substrate film, and the heating temperature of the coating layer was set to 60 ° C. The laminated body of the same thickness as each Example was obtained. A plurality of modes were detected by measuring this laminate in a single film mode. The refractive index obtained by the measurement was R2.
(1-3) Refractive index R3 at a depth of 3.0 μm from the base film side to the surface treatment layer
Measurement type: Single Film (Prism Couple)
Analysis method: Index gradient
When the refractive index changes in the depth direction in the optical laminate, the refractive index change in the depth direction can be quantitatively determined by the method using the prism coupler.
A plurality of modes were detected by measuring the optical laminate, and the refractive index change in the depth direction was calculated by Index gradient analysis. “Position of 3.0 μm depth” in the direction of the surface treatment layer from the base film side was determined based on the following formula, and the obtained refractive index was R3.
“Position of 3.0 μm depth” (position from the surface treatment side) = surface treatment layer thickness (PET base material hard coat thickness) − (3 μm)
(1-4) Ratio of components of acrylic resin eluted to the surface treatment layer among the components constituting a position of a depth of 3.0 μm from the substrate film side to the surface treatment layer X
From the following formula, the ratio X (%) of the component of the acrylic resin eluted in the surface treatment layer among the components constituting the position of the depth of 3.0 μm from the base film side to the surface treatment layer was calculated. .
X (%) = (R3-R2) × 100 / (R1-R2)
(2) Elastic modulus of base film For measuring the elastic modulus of the base film, TI900 TriboIndenter (manufactured by Hystron) was used. The base film was cut into a size of 10 mm × 10 mm, fixed to a support with TriboIndenter, and the compression elastic modulus was measured by the nanoindentation method. At that time, the position was adjusted so that the used indenter pushed in the vicinity of the center of the transparent layer. The measurement conditions are shown below.
Working indenter: Berkovich (triangular pyramid type)
Measurement method: Single indentation measurement Measurement temperature: 25 ° C
Indentation depth: 500nm
Indentation speed: 100 nm / s
(3) Functional evaluation of surface treatment layer The optical laminates obtained in Examples and Comparative Examples were cut into a size of 11 mm in width and 100 mm in length, and placed on a glass plate with the substrate film facing down. Next, on the surface treatment layer (hard coat layer) side surface of the optical laminate, steel wool # 0000 attached to a cross section of a cylinder having a diameter of 11 mm was reciprocated 10 times at a load of 800 g or 600 g at 100 mm / sec. The subsequent hard coat layer side surface was visually observed and evaluated according to the following criteria.
◯: No scratches Δ: Slightly scratched X: Scratches are remarkable (4) Adhesion evaluation The adhesion of the surface treatment layer to the substrate film was determined by the cross-cut peel test (number of cross-cuts) of JIS K-5400 : 100) and evaluated according to the following indicators.
◯: Number of cross-cut peeled is 0 ×: Number of cross-cut peeled is 1 or more

<Example 1>
1. Preparation of base film MS resin (MS-200; copolymer of methyl methacrylate / styrene (molar ratio) = 80/20, manufactured by Nippon Steel Chemical Co., Ltd.) 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 and R ⁵ 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. The by-product after 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 5 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. The obtained extruded film was simultaneously biaxially stretched twice in the length direction and the width direction at a stretching temperature of 140 ° C. The stretching speed was 10% / second in both the length direction and the width direction.
In this way, a substrate film A having a thickness of 30 μm was produced.
2. Preparation of optical laminate On one side of the base film A, 16 parts by weight of UV curable resin (4-HBA (manufactured by Osaka Organic Chemical Co., Ltd.), NK Oligo UA-53H so that the thickness after curing is 6 μm. -80BK (manufactured by Shin-Nakamura Chemical Co., Ltd.) 32 parts by weight, 48 parts by weight of Biscote # 300 (manufactured by Osaka Organic Chemical Industry Co., Ltd.), 4 parts by weight of A-GLY-9E (manufactured by Shin-Nakamura Chemical Co., Ltd.), IRGACURE907 2.4 parts by weight (manufactured by BASF) were mixed, and each was diluted with a solvent of MIBK: PGM = 50: 50 to a solid content concentration of 42.0%) to form a coating layer. Next, the coated layer was dried at 70 ° C. and UV cured to obtain an optical laminate 1 in which a hard coat layer was formed on one side of the base film A. The said optical laminated body 1 was used for each evaluation. The results are shown in Table 1.

<Example 2>
1. Production of Base Film A base film B was produced in the same manner as in Example 1, except that the amount of the core-shell type particles was 10 parts by weight, and the stretching temperature of the extruded film was 150 ° C.
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 substrate film B was used. The said optical laminated body 2 was used for each evaluation. The results are shown in Table 1.

<Example 3>
1. Production of Base Film A base film C was produced in the same manner as in Example 1 except that the amount of the core-shell type particles was 10 parts by weight and the stretch temperature of the extruded film was 160 ° C.
2. Production of Optical Laminate An optical laminate 3 in which a hard coat layer was formed on one side of the substrate film C was obtained in the same manner as in Example 1 except that the substrate film C was used. The said optical laminated body 3 was used for each evaluation. The results are shown in Table 1.

<Example 4>
1. Production of Base Film A base film D was produced in the same manner as in Example 1, except that the amount of the core-shell type particles was 13 parts by weight and the stretch temperature of the extruded film was 152 ° C.
2. Production of Optical Laminate An optical laminate 4 in which a hard coat layer was formed on one side of the substrate film D was obtained in the same manner as in Example 1 except that the substrate film D was used. The said optical laminated body 4 was used for each evaluation. The results are shown in Table 1.

<Comparative Example 1>
1. Preparation of base film 100 parts by weight of the imidized MS resin obtained above and 15 parts by weight of core-shell type particles are put into a single screw extruder, melt mixed, and a film is formed through a T die to obtain an extruded film. It was. The obtained extruded film was simultaneously biaxially stretched twice in the length direction and the width direction at a stretching temperature of 152 ° C. The stretching speed was 10% / second in both the length direction and the width direction.
In this way, a base film E having a thickness of 40 μm was produced.
2. Production of Optical Laminate An optical laminate 5 having a hard coat layer formed on one side of the substrate film E was obtained in the same manner as in Example 1 except that the substrate film E was used. The optical laminate 5 was subjected to each evaluation. The results are shown in Table 1.

<Comparative example 2>
1. Production of base film 100 parts by weight of the imidized MS resin obtained above and 23 parts by weight of core-shell type particles are put into a single screw extruder, melt mixed, and a film is formed through a T die to obtain an extruded film. It was. The obtained extruded film was simultaneously biaxially stretched twice in the length direction and the width direction at a stretching temperature of 137 ° C. The stretching speed was 10% / second in both the length direction and the width direction.
In this way, a base film F having a thickness of 40 μm was produced.
2. Production of Optical Laminate An optical laminate 6 having a hard coat layer formed on one side of the substrate film F was obtained in the same manner as in Example 1 except that the substrate film F was used. The said optical laminated body 6 was used for each evaluation. The results are shown in Table 1.

<Comparative Example 3>
1. Production of Base Film A base film G was produced in the same manner as in Example 1 except that the core-shell type particles were not blended and the stretch temperature of the extruded film was 130 ° C.
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 substrate film G was used. The said optical laminated body 7 was used for each evaluation. The results are shown in Table 1.

As is apparent from Table 1, the acrylic resin having an elastic modulus of 4 GPa or more and eluted into the surface treatment layer among components constituting a depth of 3.0 μm in the direction of the surface treatment layer from the base film side. The optical laminates of Examples 1 to 4 using a base film having a resin component ratio of less than 20% were excellent in scratch resistance and adhesion.

The optical layered body of the present invention is suitably used as a protective layer for a polarizer. The polarizing plate having the optical laminate of the present invention as a protective layer is suitably used for an image display device. Such image display devices include 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; video cameras, Household electrical equipment such as TVs and microwave ovens; Back monitors, monitors for car navigation systems, car audio equipment such as car audios; display equipment such as digital signage and commercial store information monitors; security equipment such as monitoring monitors; It can be used for various applications such as nursing care / medical devices such as nursing monitors and medical monitors.

DESCRIPTION OF SYMBOLS 10 Base film 20 Surface treatment layer 100 Optical laminated body

Claims

A base film, and a surface treatment layer formed on one side of the base film,
The base film includes an acrylic resin and core-shell type particles dispersed in the acrylic resin,
The base film has an elastic modulus of 4.0 GPa or more,
The ratio of the component of the acrylic resin eluted to the surface treatment layer among the components constituting the position of the depth of 3.0 μm from the base film side to the surface treatment layer is less than 20%. Laminated body.
The refractive index of the base film is R1, the refractive index of the surface treatment layer is R2, and the refractive index at a depth of 3.0 μm in the direction of the surface treatment layer from the base film side is R3. When
R3> 0.2R1 + 0.8R2 (where R1 <R2)
The optical laminate according to claim 1, wherein
3. The optical laminate according to claim 1, wherein the thickness of the surface treatment layer is 3 μm to 20 μm.
The optical laminate according to any one of claims 1 to 3, wherein the base film contains 5 to 20 parts by weight of the core-shell type particles with respect to 100 parts by weight of the acrylic resin.
5. The acrylic resin 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. Optical laminate.
The optical laminate according to any one of claims 1 to 5, wherein the surface treatment layer is a cured layer of a resin applied on the base film.
The optical laminate according to any one of claims 1 to 6, 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 polarizer, and a protective layer disposed on one side of the polarizer,
A polarizing plate, wherein the protective layer is the optical layered body according to claim 1.
An image display device comprising the polarizing plate according to claim 8.